Title of Invention	A LOW PRESSURE DIE CASTING INSTALLATION AND A METHOD OF OPERATING THE SAME
Abstract	ABSTRACT 454/MAS/2002 "A LOW PRESSURE DIE CASTING INSTALLATION AND A METHOD OF OPERATING THE SAME" A low-pressure die casting installation having at least one casting station, at least one further working station and at least one handling unit for conveying a permanent mold which comprises two permanent-mold halves, characterized in that at least one first handling unit of a first design is present, which is suitable for conveying a closed permanent mold without having means to open the mold, that at least one second handling unit of a second design is present, which is suitable for conveying an open permanent mold and that at least one opening and closing device is present

Title of Invention

A LOW PRESSURE DIE CASTING INSTALLATION AND A METHOD OF OPERATING THE SAME

Abstract

ABSTRACT 454/MAS/2002 "A LOW PRESSURE DIE CASTING INSTALLATION AND A METHOD OF OPERATING THE SAME" A low-pressure die casting installation having at least one casting station, at least one further working station and at least one handling unit for conveying a permanent mold which comprises two permanent-mold halves, characterized in that at least one first handling unit of a first design is present, which is suitable for conveying a closed permanent mold without having means to open the mold, that at least one second handling unit of a second design is present, which is suitable for conveying an open permanent mold and that at least one opening and closing device is present

Full Text	The invention relates to low-pressure die casting installations and to an operating method as described. Low-pressure die casting installations are known, for example, from CH 690 356 and EP-A 0 824 983. In known installations, the permanent molds, which comprise two permanent-mold halves, are clamped securely into a handling unit, which is also known as a manipulator. This unit is in turn fixedly connected to a conveyor device, which moves the manipulator together with the permanent mold from one working station to the next. The manipulator includes an opening and closing mechanism, by means of which the permanent mold can be opened and closed according to working steps which are to be carried out at the respective working station, for example insertion of cores, casting, removal of casting, cleaning, application of a film of wash. The permanent mold is in this case always conveyed in the closed state. On account of the high inherent weight of the permanent mold, the opening and closing mechanism requires robust guide parts for the permanent-mold halves and the corresponding drive elements. Furthermore, the manipulator has to apply considerable forces in order to hold the two permanent-mold halves together in the casting station against the pressure of the rising liquid metal, so that no edges are formed on the casting. Therefore, to apply the required closing force and to move the permanent-mold halves relative to one another, the manipulator has a high inherent weight. This mass has to be moved by the conveyor device, with a corresponding outlay on energy and time. The manipulator is of mechanically complex design and is therefore expensive to produce and maintain. A certain time is required each time the permanent mold has to be opened and closed in the individual working stations, with the result that the duration of a total operating cycle is increased and the permanent molds may under certain circumstances be cooled to below a minimum temperature, requiring additional heating steps. In addition to the high inertia of the system caused by the large masses, the lack of flexibility when changing the casting die or the permanent mold represents a further drawback of known installations. The permanent mold has to be removed from the manipulator, with a corresponding outlay on assembly. The invention is therefore based on the object of providing a low-pressure die casting installation in which the abovementioned drawbacks are avoided, the manipulators are of mechanically simple design and transport between the individual working stations takes place quickly and with a reduced outlay on energy. The object is achieved by low-pressure die casting installations having the features of this invention and by a method for operating a low-pressure die casting installation of this type having the features of this invention. Advantageous refinements of the invention will emerge from the dependent claims, the description and the drawings. In a low-pressure die casting installation which has at least one casting station and at least one further working station, preferably a core-insertion station, a removal station, a blasting station and a dipping and/or spraying station, in a first variant of the invention at least one first handling unit of a first design and at least one second handling unit of a second design are present. The first handling unit is suitable for conveying a closed permanent mold, and the - second handling unit is suitable for conveying an open permanent mold, i.e. each handling unit is tailored to the role which it is intended to fulfil. The handling unit of the first design is optimized for the closing function and for conveying the closed permanent mold. The permanent mold is preferably received by a receiving shaft which surrounds the closed permanent mold from at least two sides, preferably with an approximately accurate fit. The permanent-mold halves are pressed toward one another and the permanent mold fixed within the shaft by a closure mechanism, which comprises, for example, at least one closure piston. The mechanical outlay required is low, since the closure pistons only have to clamp the permanent mold inside the receiving shaft, with a short travel being sufficient. There is no need for means to open the permanent mold using the first handling unit. During casting, the permanent mold remains in the first handling unit. The handling unit of the second design is optimized for conveying the open permanent mold. Time is saved as a result of the permanent molds being moved in the open state between the working stations which require processing in the open state. The second handling unit has two holding elements, which are each used to hold one permanent-mold half, the held permanent-mold halves being at a distance from one another and preferably being oriented parallel to one another. Depending on the method step which is to be carried out, the open permanent mold is transferred to the working station for further processing, for example to the core-insertion station, or remains attached to the handling unit during the corresponding working step, for example during graphitizing of the permanent mold. On account of the functionally optimized design, the handling units make do substantially without moving parts and rigid, heavy guide elements. Where necessary, the opening or closing movement is produced by a stationary opening and/or closing device directly at the working stations. 5 In a second variant of the invention, the casting station is assigned a clamping unit for receiving a permanent mold with coupling elements, which holds the permanent-mold halves together during casting. 10 Furthermore, there is a gripping and conveying system which has at least one handling unit and is used to receive the permanent mold by engaging on the coupling elements and to convey the permanent mold between the further working station and the casting station or 15 further working stations, the permanent mold being transferred to or picked up by the clamping unit at the casting station. Therefore, the permanent molds are not clamped fixedly in a manipulator, but rather are moved as such between and within the individual stations. It 20 is also possible for handling units of the first or second design in accordance with the first variant of the invention to be used. The required closing force is applied in the casting station by the stationary clamping unit, which receives the permanent mold 25 preferably with a tight fit and in a clamping manner. Since the permanent mold has uniform external dimensions irrespective of the shape of the casting, for example has at least a predetermined thickness, the clamping unit can be manufactured substantially from a 30 single piece, into which the permanent mold is inserted and, if necessary, clamped with ' relatively little force. The clamping unit does not have to be moved. The permanent mold is inserted into the clamping unit and removed from the clamping unit again by means of the 35 handling unit. During the actual conveying operation, there is no need for high levels of forces to be applied in order to hold the permanent-mold halves together. Therefore, the handling unit may, for example, have a very lightweight gripping and transporting unit, which only presses the permanent-mold halves lightly onto one another in order to keep them closed. The handling unit used may, for example, also be a robot. Overall, the handling unit does not 5 have to be as robust as when the manipulators which have hitherto been customary are used, since the masses which have to be moved are lower. It therefore becomes more simple and inexpensive in terms of design. 10 Since the permanent mold is not fixedly coupled to a common handling unit which covers all the stations, the installations according to the invention can be of-completely modular structure. If necessary, further working stations can be introduced or modified, with 15 the result that the flexibility of the installation is increased. The two variants of the invention may also be combined, for example as a result of the permanent mold in the 20 closed or open state being conveyed using handling units of the first and second design and being transferred to a stationary clamping unit at the casting station. In this way, the handling unit of the first design can be made even more lightweight. 25 Permanent molds with a standardized external shape are preferably used in the installations according to the invention. A permanent mold of this type has, for example, a base body, which includes the actual casting 30 die, and coupling elements, for example in the form of lateral flanges or plates, which are' connected thereto. These coupling elements are arranged in such a manner that the spatial dimensions of the permanent mold, at least in one spatial direction, are independent of the 35 size of the base body. This makes it possible to use a plurality of different casting dies and to exchange them as desired without outlay on design. The holding elements or devices of the handling units, the clamping unit and the other opening and closing devices may be equipped with a uniform gripper system which makes it possible to manipulate the permanent mold in the desired way, for example to press it together during casting, to pull it apart and pivot it for cooling, etc. The receiving shaft of the first handling unit therefore preferably has a depth which is matched to the distance between the coupling elements of the permanent-mold halves in the closed state. The handling units are connected to in each case one drive device and can be moved independently of one another. The handling units can preferably move along a linear guide rail and be adjusted in terms of their height. In an advantageous refinement of the invention, the permanent molds have a coding which indicates the type of permanent mold, for example the shape of the casting. This is read by means of suitable reader units at the individual stations and is transmitted to a system control unit, which may be central or local, via a corresponding signal. The system control unit provides the working station with the required data for controlling the working process. By way of example, a predetermined pressure curve, i.e. the time-dependent pressure profile, which is adapted to the shape of the casting, is set in the casting station. By way of example, cooling is carried out for a predetermined time, which is dependent on the casting die, in the graphitizing station. By way of example, cleaning nozzles are moved over the open permanent mold as a function of the casting die in a cleaning station. The coding is preferably mechanical, ' for example an arrangement of pins, but may also be produced in some other way, for example by a bar code or a data carrier. Robust mechanical coding can be read reliably even when used under the somewhat unclean operating conditions which prevail during casting. It is preferable for each working station to be assigned a local control unit, which controls the local working steps. The relevant process data are preferably input at a central control unit and are requested by the local control unit. Exemplary embodiments of the invention are illustrated in the drawings and described below. In the purely diagrammatic drawings: figs la-e show permanent molds for use with the installation according to the invention; figs. 2a,b show a first handling unit according to-the first variant of the invention for conveying a closed permanent mold; figs. 3a,b show a second handling unit according to the first variant of the invention for conveying an open permanent mold; fig. 4 shows a low-pressure die casting installation in accordance with the first variant of the invention; figs. 5-10 show various working stations of an installation according to the first variant of the invention; figs. 11a, b show illustrations of the movement of the handling units of the installation shown in fig. 4 between the individual stations; fig. 12 shows a plan view of an installation in accordance with the second variant of the invention; figs. 13-15 show various working stations for an installation according to the second variant of the invention; figs. 16a-c show various views of the way in which a permanent mold according to the invention is coupled to the gripping and conveying system. ,, ^, Examples of permanent molds according to the invention are illustrated in figures la,b and figures Ic-e. The permanent mold 3 comprises two permanent-mold halves 3a, 3b which are designed mirror-symmetrically with respect to one another and each have lateral coupling elements 4. These coupling elements are in the form of-a plate 5, which is connected to the base body 9, which bears the actual casting die, via webs 34. The permanent mold 3 can be received by and secured to the first or second handling unit 1, 10 by engagement on the coupling element 4, in this case on pins 15 connected thereto and/or cutouts 8 arranged therein. Opening and/or closing devices, ejector devices or other holding devices for the permanent mold which are arranged at the working stations can engage on the coupling elements 4, for example a slot 16 arranged centrally in the plate 5. The coupling elements 4 are designed in such a way that the coupling points for the handling units 1, 10 or other holding devices, in the closed state, are always in the same position relative to one another irrespective of the size and shape of the base body 9. The base body may, for example, be lengthened (cf. base body 9' in figures la, b) or have a changed depth (not shown), in which latter case the webs 34 would have to be lengthened accordingly. Figs. Ic-e show a slightly modified permanent mold 3. A coding 39, in this case an arrangement of short pins, which can be read by a suitable reading unit, for example by mechanical scanning, is arranged on one of the plates 5. An opening 41 for the ejector cylinder 48 to pass through (fig. 14a) is present in the plates 5. This cylinder moves an ejector plate 42, by means of which the castings are removed from their die. Figures la,b and 2a,b show the two types of handling units 1, 10 which are used in a low-pressure die casting installation according to the first variant of the invention. The first handling unit 1, which is suitable for conveying the closed permanent mold 3, has a frame 2 which is U-shaped in cross section and forms a receiving shaft 35 which is open on three sides. The side walls 2a, 2b of the frame 2 bear a closure device 6, which in the present case comprises in each case four hydraulically driven closure cylinders 7. As shown in figure 4, the handling units 1, 10 are in each case connected to a drive device 17, by means of which they can be moved in the horizontal direction along a guide rail 18 and in the vertical direction. As a result of movement in the vertical direction, the frame 2 is placed onto a closed permanent mold 3 which is in a standing position, so that this mold is received with a small degree of play in the receiving shaft 35. It is fixed by the closure cylinders 7, which engage in the cutouts 8 in the coupling element 4. The travel of the closure cylinders 7 which is required for the fixing operation is very low, at a few millimeters (approx. 10 - 20 ram) . The first handling unit 1 does not have further movable parts, and consequently it can be produced with little structural outlay. The closure device 6 holds the closed permanent mold 3 inside the first handling unit 1 and holds it together during the casting operation. The second handling unit 10 shown in figures 3a,b is suitable for conveying the open permanent mold with permanent-mold halves 3a, 3b which are at a distance from one another and aligned parallel to one another. It also comprises a U-shaped frame 11, the side walls 11a, lib of which are at a greater distance than the frame 2 of the first handling unit 1. Each side wall 11a, lib comprises a holding device 12, which in the present case comprises holding elements 13, which interact with the pins 15 of the coupling elements 4, and holding cylinders 14, which interact with the cutouts 8. The permanent-mold halves 3a, 3b are held inside the second handling unit 10 by the holding device 12. The permanent mold is received as a result of the second handling unit 10 being placed from above onto the open permanent mold 3, which is standing upright, and then the holding cylinders 14 being moved. Other gripper mechanisms are possible as well as closure cylinders. In this case too, as in the first handling unit 1, there are no movable parts apart from the closure cylinders. Figure 4 shows a preferred structure of the low-pressure die casting installation according to the invention as a linear arrangement. A casting station 19 and further working stations, in this case a core-insertion station 20, a removal station 21, a permanent-mold exchange station 22, a cleaning station 23 and a graphitizing station 24, are arranged along a straight line at preferably regular intervals. Between the casting station 19 and the core-insertion station 20 there is a waiting position 22'; the area above the permanent-mold exchange station 22 may also be used as a waiting position if there is not currently a permanent mold being exchanged. The left-hand part of the drawing shows the casting station 19 in a side view, rotated through 90°. The casting installation has a first handling unit 1 and two second handling units 10, 10', which are in each case connected to a drive device 17, which moves the handling units 1, 10, 10' along a linear guide rail 18 and, moreover, allows the height of the handling units to be adjusted. The handling units 1, 10, 10' can be displaced independently of one another. Their movement is controlled by a control device (not shown). Since the permanent molds are not fixedly connected to a specific handling unit, it is advantageously also possible for three handling units to be used in the present linear arrangement. This considerably increases the cycle time of the installation compared to known installations. One example of the movement of the permanent molds is illustrated in figures 11a,b. According to this example, the first handling unit 1 receives a closed permanent mold at the core-insertion station and moves it to the casting station 19 and then to the removal station 21. The closed permanent mold is transferred to the removal station 21, where it is opened, after which the casting is removed. During this time, the first-handling unit is already moving back to the core-insertion station in order to pick up a new permanent mold. The emptied permanent mold is picked up by the second handling unit 10 at the removal station 21 and, in the open state, is conveyed to the cleaning station 23 and transferred to the latter. After this transfer, the second handling unit 10 moves to the waiting position 22'. Finally, the cleaned permanent mold is picked up from the cleaning station 23 by the further second handling unit 10' and moved into the graphitizing station 24, where it remains on the further second handling unit 10' during the graphitizing. Then, it is moved to the core-insertion station 20, where the cycle begins again. The movements of the other two handling units which are carried out during this period can be found in figure 11a. Overall, it is possible to operate with three permanent molds synchronously, and it is possible to achieve cycle times of the installation in ' the region of 40-60 seconds. Since each permanent mold returns to the casting station 19 after three times the cycle time, no additional heating steps are required in order to keep the permanent mold at the desired temperature. The temperature of the permanent mold is measured and is kept constant by means of the washing or spraying time. Figures 5-10 diagrammatically depict the structure of the individual working stations, which in the text which follows are explained only where they differ from the structure of known stations. The structure of the casting station 19 shown in figure 5, with an induction furnace, corresponds to the prior art. The permanent mold is placed onto the riser 25 of the furnace by means of the first handling unit 1, which also applies the closure force required to close the permanent-mold halves 3a, 3b. The core-insertion station 20 shown in figures 6a-b comprises a carriage 27 which can move transversely to-the direction of the guide rail 18 (figure 4) and to which an opening and closing device 26 is connected in such a manner that it can pivot about a horizontal axis. In the lying state (left-hand part of figure 6a), the opening and closing device can receive a permanent mold 3 which is presented in open form. The permanent mold is gripped by the opening and closing device 26 at its coupling elements 4. This is diagrammatically indicated in figures 6c-d: the permanent mold 3 is placed from above onto holding cylinders 14' which engage in lower cutouts 8 in the plate 5. Then, closure cylinders 7' move into lateral cutouts 8 in the plate 5, so that the latter is clamped. As a result of the opening and closing device 26 being pivoted through 90° (right-hand part of figure 6a), the permanent-mold halves 3a, 3b move into a horizontal position, so that the sand core can be inserted manually. The permanent mold 3 is finally closed and the opening and closing device is pivoted back into the lying position. The first handling unit 1 can pick up the closed permanent mold 3 in this state. Figure 6b shows the view of the core-insertion station which is sketched in figure 4, while figure 6a shows a view which is rotated through 90° with respect to this view. The removal station 21 in figure 7 receives a closed permanent mold from the first handling station 1, and opens it by means of an internal opening and closing device 26', so that the casting 28 can be ejected and removed using an ejector device. The permanent mold is then picked up in the open state. An open permanent mold is transferred by a second handling unit 10 to the cleaning station which is outlined in figure 8 and has, in a housing 30, a suitable receiving means for the open permanent mold. The permanent mold is blasted or washed in a programmed manner. Then, the permanent mold is picked up by the further second handling unit 10' and moved to the graphitizing station 24 shown in figure 9, where it is lowered together with the handling unit 10', wash is sprayed in by a spraying unit 31 and the permanent mold is then raised again. The permanent-mold exchange station 22 shown in figure 10 comprises a carriage 32 for carrying away a permanent mold which is to be exchanged and a carriage 33 for bringing in a new, preheated permanent mold. The carriages can move transversely with respect to the direction of the guide rail 18 (figure 4) . After a permanent mold which is to be exchanged has been deposited, the carriage 32 is moved sideways, so that the carriage 33 adopts the position which was originally held by the carriage 32, and the permanent-mold halves 3a, 3b are taken hold of in the open state. Figure 12 shows a plan view of a low-pressure die casting installation according to the second variant of the invention, having a casting station 19, a removal and cleaning station 21/23, a permanent-mold exchange station 22, a cooling and wash station with core-insertion station 20 and a gripping and conveying system for moving the permanent molds. The gripping and conveying system comprises three handling units, which are moved along guide rails 18 arranged in the shape of a triangle. The permanent molds 3 are shown in figs la-e, and the individual stations are shown in figs. IS¬IS. Figs. 13a,b respectively show a side view and a plan view of a casting station 19 which is known per se and has a clamping unit 43. The clamping unit 43 comprises a rectangular, continuous frame 43a which, in its interior, has receiving elements 44 for receiving the coupling elements 4 of the permanent mold 3. The permanent mold 3 is introduced into the clamping unit 4 3 from above. In addition, clamping elements, which clamp the permanent mold 3 in the clamping unit 43 after it has been introduced, may be provided for the purpose of holding the permanent mold 3. The clamping unit 43 is secured to a vertically oriented rotary column 45 and can be pivoted about a vertical axis and also displaced in the vertical direction. Figs. 14a-c show a removal and cleaning station 21/23 in a view from the side, perpendicular to the conveying direction (fig. 14a), from above (fig. 14b) and from the side in the conveying direction (fig. 14c). An opening and closing device 26, which is accessible to permanent molds 3 from above, is present. The opening and closing device 26 has holding elements 13, which likewise engage on the lateral plates 5 of the coupling elements 4 of the permanent molds 3. The distance between the holding elements 13, as seen in the conveying direction, is in this case variable, so that the two permanent-mold halves 3a, ' 3b can be pulled apart for removal of the casting and for cleaning (dashed illustration of the permanent-mold half 3b'). The opening and closing movement of the receiving unit 26 is brought about by cylinders 46. Guide rods 27 are used to guide the holding elements 13 in the horizontal direction. An ejector cylinder 48 is used to move an ejector plate 42, which is shown in more detail in figs. Ic-d and is used to release the finished casting 28 from the die, so that they can be picked up by a removal unit 51. After removal, a cleaning nozzle 29 is moved along the open permanent-mold parts 3a, 3b. The movement of the nozzle 29 can be controlled as a function of the casting die. The station also has a blasting unit 49. Figs. 15a,b show a cooling and wash station having a core-insertion station in a side view and plan view, respectively. The permanent mold 3 is located in an opening and closing device 26'. The holding elements 13 of this device are substantially designed in the same way as those of the casting station 19 or cleaning station and once again engage on the coupling elements 4 of the permanent-mold halves 3a, 3b. The holding elements 13 move apart in order to open the permanent mold 3 (as shown in dashed lines) and pivot about horizontal axes Dl, Dl', in order for the permanent-mold halves 3a, 3b to be dipped in the cooling and wash bath 35. After pivoting back into the starting position with vertical permanent-mold halves 3a, 3b, the entire opening and closing device 26' pivots about a further horizontal axis D2 (further position illustrated in dashed lines). In this position, the cores are placed onto the lower permanent-mold half 3a, the permanent mold 3 is closed, the opening and closing device 26' is pivoted back and the permanent mold 3 is removed in the vertical direction by the gripping and conveying system. Figs. 16a-c show the way in which' a permanent mold according to the invention is coupled to a handling unit which can be used for the second variant of the invention and for closed conveying in the first variant of the invention. The handling unit comprises a horizontal plate 53, on the underside of which holding elements 13' are arranged, the clear width between which elements is variable. They have a protuberance which engages in a corresponding notch in the pins 15 of the coupling elements 4. In this way, the permanent molds are fixed in both the horizontal direction and the vertical direction and are kept closed during conveying. WE CLAIM: 1. A low-pressure die casting installation having at least one casting station (19), at least one further working station (20, 21, 22, 23, 24) and at least one handling unit (1, 10, 10') for conveying a permanent mold (3) which comprises two permanent-mold halves (3a, 3b), characterized in that at least one first handling unit (1) of a first design is present, which is suitable for conveying a closed permanent mold (3) without having means to open the mold, that at least one second handling unit (10, 10') of a second design is present, which is suitable for conveying an open permanent mold (3) and that at least one opening and closing device (26, 26') is present- 2. The low-pressure die casting installation as claimed in claim 1, wherein the first handling unit (1) is arranged in such a manner that it is able to convey a closed permanent mold (3) from and to the casting station (19), and wherein the second handling unit (10, 10') is arranged in such a manner that it is able to convey an open permanent mold (3) from and to the further working station (20, 21, 22, 23, 24). 3. The low-pressure die casting installation as claimed in claim 1 or 2, wherein the first handling unit (1) has a receiving shaft (35) and a closure mechanism (6), the cross section of the receiving shaft (35) being matched to the cross section of a closed permanent mold (3), in such a manner that the receiving shaft (35) is capable to receive the permanent mold (3) and the closure mechanism (6) being able to press the permanent- mold halves (3a, 3b) of a permanent mold (3) which has been received in the receiving shaft (35) toward one another. 4. The low-pressure die casting installation as claimed in claim 3, wherein the first handling unit (1) contains only fixed parts with the exception of the closure mechanism (6). 5. The low-pressure die casting installation as claimed in claim 3 or 4, wherein the closure mechanism (6) comprises at least one hydraulically operated closure cylinder (7). 6. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein the second handling unit (10, 10') has two holding devices (12) , which are each used to hold a permanent-mold half (3a, 3b), in such a manner that the permanent-mold halves (3 a, 3 b) are at a distance from one another and are preferably oriented parallel to one another. 7. The low-pressure die casting installation as claimed in claim 6, wherein the holding device (12) comprises a gripper mechanism, which is used to take hold of the permanent-mold halves (3a, 3b). 8. The low-pressure die casting installation as claimed in claim 6 or 7, wherein second handling unit (10, 10') comprises only fixed parts with the exception of the holding device (12). 9. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein the handling units (1, 10, 10') are forceable independently of one another. 10. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein at least each of a core-insertion station (20) and a removal station (21) has an opening and closing device (26, 26') which is able to receive a permanent mold and to open and close the mold. 11. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein at least one handling unit (1) of the first design and at least two handling units (10, 10') of the second design are present. 12. A low-pressure die casting installation having at least one casting station (19), at least one further working station (19, 20, 21, 22, 23, 24), and at least one handling unit is capable to receive the mold (3) and to convey the mold between the casting station and the further working station characterized in that the casting station (19) is assigned a clamping unit with a frame (43a) for receiving a permanent mold (3) which has coupling elements (4), the closed mold (3) is insertable into the frame (43a) and is clamped therein and the clamping unit (43) is capable to hold permanent-mold halves (3a, 3b) together during casting, and that the handling unit is capable to receive the permanent mold (3) by engaging on the coupling elements (4). 13. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein set of permanent molds (3) each comprising a base body (9, 9'), and coupling elements (4), which are connected thereto and are arranged in such a manner that the spatial dimensions of the set of permanent molds (3), at least in one spatial direction, are independent of the size of their base bodies (9, 9'). 14. The low-pressure die casting installation as claimed in claim 13, wherein each permanent mold half (3a, 3b) is assigned at least one coupling element (4) of a predetermined shape and size, and wherein the spatial position of the coupling elements (4) relative to one another is independent of the size of the base body (9, 9'). 15. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein the following further working stations are present: a core-insertion station (20), a removal station (21), a cleaning station (23) and a graphitizing station (24). 16. The low-pressure die casting installation as claimed in claim 13 or 14, wherein the base body (9, 9') is cuboidal and is capable of being split into two halves, and the coupling elements (4) are plates (5), struts or other coupling parts which are arranged parallel to one another laterally with respect to the base body (9, 9'), are connected to the base body by means of pins (34) and on which a handling unit engages, the plates (5), struts or other coupling parts having the same shape and being at the same distance from one another irrespective of the size of the base body (9, 9'). 17. The low-pressure die casting installation as claimed in claim 13, 14, or 16 wherein the permanent mold (3) has a locking system for holding the two permanent-mold halves (3a, 3b) together. 18. The low-pressure die casting installation as claimed in claim 13, 14, 16 or 17 wherein the permanent mold (3) has a coding (39), which is preferably mechanical or electronic. 19. A method for operating the low-pressure die casting installation as claimed in any one of claims 1-11, in which the first handling unit (1) conveys a permanent mold (3) in the closed state from a core-insertion station (20) to the casting station (19), holds it closed during the casting and, after the casting, transfers it in the closed state to a removal station (21), in which the permanent ipold (3) is opened, and in which the second handling unit (10, 10') picks up the open permanent mold ( from the removal station (21) and conveys it in the open state to a further working station (22, 23, 24). 20. A method for operating the low-pressure die casting installation as claimed in claim 12, in which the at least one handling unit introduces the mold (3) into or picks up the mold (3) from the clamping unit (43).

Full Text

The invention relates to low-pressure die casting installations and to an operating method as described.
Low-pressure die casting installations are known, for example, from CH 690 356 and EP-A 0 824 983. In known installations, the permanent molds, which comprise two permanent-mold halves, are clamped securely into a handling unit, which is also known as a manipulator. This unit is in turn fixedly connected to a conveyor device, which moves the manipulator together with the permanent mold from one working station to the next. The manipulator includes an opening and closing mechanism, by means of which the permanent mold can be opened and closed according to working steps which are to be carried out at the respective working station, for example insertion of cores, casting, removal of casting, cleaning, application of a film of wash. The permanent mold is in this case always conveyed in the closed state. On account of the high inherent weight of the permanent mold, the opening and closing mechanism requires robust guide parts for the permanent-mold halves and the corresponding drive elements. Furthermore, the manipulator has to apply considerable forces in order to hold the two permanent-mold halves together in the casting station against the pressure of the rising liquid metal, so that no edges are formed on the casting. Therefore, to apply the required closing force and to move the permanent-mold halves relative to one another, the manipulator has a high inherent weight. This mass has to be moved by the conveyor device, with a corresponding outlay on energy and time. The manipulator is of mechanically complex design and is therefore expensive to produce and maintain. A certain time is required each time the permanent mold has to be opened and closed in the individual working stations, with the result that the duration of a total operating cycle is increased and the permanent molds may under

certain circumstances be cooled to below a minimum temperature, requiring additional heating steps.
In addition to the high inertia of the system caused by the large masses, the lack of flexibility when changing the casting die or the permanent mold represents a further drawback of known installations. The permanent mold has to be removed from the manipulator, with a corresponding outlay on assembly.
The invention is therefore based on the object of providing a low-pressure die casting installation in which the abovementioned drawbacks are avoided, the manipulators are of mechanically simple design and transport between the individual working stations takes place quickly and with a reduced outlay on energy.
The object is achieved by low-pressure die casting installations having the features of this invention and by a method for operating a low-pressure die casting installation of this type having the features of this invention. Advantageous refinements of the invention will emerge from the dependent claims, the description and the drawings.
In a low-pressure die casting installation which has at least one casting station and at least one further working station, preferably a core-insertion station, a removal station, a blasting station and a dipping and/or spraying station, in a first variant of the invention at least one first handling unit of a first design and at least one second handling unit of a second design are present. The first handling unit is suitable for conveying a closed permanent mold, and the -

second handling unit is suitable for conveying an open permanent mold, i.e. each handling unit is tailored to the role which it is intended to fulfil.
The handling unit of the first design is optimized for the closing function and for conveying the closed permanent mold. The permanent mold is preferably received by a receiving shaft which surrounds the closed permanent mold from at least two sides, preferably with an approximately accurate fit. The permanent-mold halves are pressed toward one another and the permanent mold fixed within the shaft by a closure mechanism, which comprises, for example, at least one closure piston. The mechanical outlay required is low, since the closure pistons only have to clamp the permanent mold inside the receiving shaft, with a short travel being sufficient. There is no need for means to open the permanent mold using the first handling unit. During casting, the permanent mold remains in the first handling unit.
The handling unit of the second design is optimized for conveying the open permanent mold. Time is saved as a result of the permanent molds being moved in the open state between the working stations which require processing in the open state. The second handling unit has two holding elements, which are each used to hold one permanent-mold half, the held permanent-mold halves being at a distance from one another and preferably being oriented parallel to one another. Depending on the method step which is to be carried out, the open permanent mold is transferred to the working station for further processing, for example to the core-insertion station, or remains attached to the handling unit during the corresponding working step, for example during graphitizing of the permanent mold.
On account of the functionally optimized design, the handling units make do substantially without moving

parts and rigid, heavy guide elements. Where necessary, the opening or closing movement is produced by a stationary opening and/or closing device directly at the working stations. 5
In a second variant of the invention, the casting station is assigned a clamping unit for receiving a permanent mold with coupling elements, which holds the permanent-mold halves together during casting.
10 Furthermore, there is a gripping and conveying system which has at least one handling unit and is used to receive the permanent mold by engaging on the coupling elements and to convey the permanent mold between the further working station and the casting station or
15 further working stations, the permanent mold being transferred to or picked up by the clamping unit at the casting station. Therefore, the permanent molds are not clamped fixedly in a manipulator, but rather are moved as such between and within the individual stations. It
20 is also possible for handling units of the first or second design in accordance with the first variant of the invention to be used. The required closing force is applied in the casting station by the stationary clamping unit, which receives the permanent mold
25 preferably with a tight fit and in a clamping manner. Since the permanent mold has uniform external dimensions irrespective of the shape of the casting, for example has at least a predetermined thickness, the clamping unit can be manufactured substantially from a
30 single piece, into which the permanent mold is inserted and, if necessary, clamped with ' relatively little force. The clamping unit does not have to be moved. The permanent mold is inserted into the clamping unit and removed from the clamping unit again by means of the
35 handling unit. During the actual conveying operation, there is no need for high levels of forces to be applied in order to hold the permanent-mold halves together. Therefore, the handling unit may, for example, have a very lightweight gripping and

transporting unit, which only presses the permanent-mold halves lightly onto one another in order to keep them closed. The handling unit used may, for example, also be a robot. Overall, the handling unit does not 5 have to be as robust as when the manipulators which have hitherto been customary are used, since the masses which have to be moved are lower. It therefore becomes more simple and inexpensive in terms of design.
10 Since the permanent mold is not fixedly coupled to a common handling unit which covers all the stations, the installations according to the invention can be of-completely modular structure. If necessary, further working stations can be introduced or modified, with
15 the result that the flexibility of the installation is increased.
The two variants of the invention may also be combined, for example as a result of the permanent mold in the
20 closed or open state being conveyed using handling units of the first and second design and being transferred to a stationary clamping unit at the casting station. In this way, the handling unit of the first design can be made even more lightweight.
25
Permanent molds with a standardized external shape are preferably used in the installations according to the invention. A permanent mold of this type has, for example, a base body, which includes the actual casting
30 die, and coupling elements, for example in the form of lateral flanges or plates, which are' connected thereto. These coupling elements are arranged in such a manner that the spatial dimensions of the permanent mold, at least in one spatial direction, are independent of the
35 size of the base body. This makes it possible to use a plurality of different casting dies and to exchange them as desired without outlay on design. The holding elements or devices of the handling units, the clamping unit and the other opening and closing devices may be

equipped with a uniform gripper system which makes it possible to manipulate the permanent mold in the desired way, for example to press it together during casting, to pull it apart and pivot it for cooling, etc. The receiving shaft of the first handling unit therefore preferably has a depth which is matched to the distance between the coupling elements of the permanent-mold halves in the closed state. The handling units are connected to in each case one drive device and can be moved independently of one another. The handling units can preferably move along a linear guide rail and be adjusted in terms of their height.
In an advantageous refinement of the invention, the permanent molds have a coding which indicates the type of permanent mold, for example the shape of the casting. This is read by means of suitable reader units at the individual stations and is transmitted to a system control unit, which may be central or local, via a corresponding signal. The system control unit provides the working station with the required data for controlling the working process. By way of example, a predetermined pressure curve, i.e. the time-dependent pressure profile, which is adapted to the shape of the casting, is set in the casting station. By way of example, cooling is carried out for a predetermined time, which is dependent on the casting die, in the graphitizing station. By way of example, cleaning nozzles are moved over the open permanent mold as a function of the casting die in a cleaning station. The coding is preferably mechanical, ' for example an arrangement of pins, but may also be produced in some other way, for example by a bar code or a data carrier. Robust mechanical coding can be read reliably even when used under the somewhat unclean operating conditions which prevail during casting.
It is preferable for each working station to be assigned a local control unit, which controls the local

working steps. The relevant process data are preferably input at a central control unit and are requested by the local control unit.
Exemplary embodiments of the invention are illustrated in the drawings and described below. In the purely diagrammatic drawings:
figs la-e show permanent molds for use with the installation according to the invention;
figs. 2a,b show a first handling unit according to-the first variant of the invention for conveying a closed permanent mold;
figs. 3a,b show a second handling unit according to the first variant of the invention for conveying an open permanent mold;
fig. 4 shows a low-pressure die casting installation in accordance with the first variant of the invention;
figs. 5-10 show various working stations of an installation according to the first variant of the invention;
figs. 11a, b show illustrations of the movement of the handling units of the installation shown in fig. 4 between the individual stations;
fig. 12 shows a plan view of an installation in accordance with the second variant of the invention;
figs. 13-15 show various working stations for an installation according to the second variant of the invention;

figs. 16a-c show various views of the way in which a
permanent mold according to the invention is coupled to the gripping and conveying system. ,, ^,
Examples of permanent molds according to the invention are illustrated in figures la,b and figures Ic-e. The permanent mold 3 comprises two permanent-mold halves 3a, 3b which are designed mirror-symmetrically with respect to one another and each have lateral coupling elements 4. These coupling elements are in the form of-a plate 5, which is connected to the base body 9, which bears the actual casting die, via webs 34. The permanent mold 3 can be received by and secured to the first or second handling unit 1, 10 by engagement on the coupling element 4, in this case on pins 15 connected thereto and/or cutouts 8 arranged therein. Opening and/or closing devices, ejector devices or other holding devices for the permanent mold which are arranged at the working stations can engage on the coupling elements 4, for example a slot 16 arranged centrally in the plate 5. The coupling elements 4 are designed in such a way that the coupling points for the handling units 1, 10 or other holding devices, in the closed state, are always in the same position relative to one another irrespective of the size and shape of the base body 9. The base body may, for example, be lengthened (cf. base body 9' in figures la, b) or have a changed depth (not shown), in which latter case the webs 34 would have to be lengthened accordingly.
Figs. Ic-e show a slightly modified permanent mold 3. A coding 39, in this case an arrangement of short pins, which can be read by a suitable reading unit, for example by mechanical scanning, is arranged on one of the plates 5. An opening 41 for the ejector cylinder 48 to pass through (fig. 14a) is present in the plates 5. This cylinder moves an ejector plate 42, by means of

which the castings are removed from their die.
Figures la,b and 2a,b show the two types of handling units 1, 10 which are used in a low-pressure die casting installation according to the first variant of the invention. The first handling unit 1, which is suitable for conveying the closed permanent mold 3, has a frame 2 which is U-shaped in cross section and forms a receiving shaft 35 which is open on three sides. The side walls 2a, 2b of the frame 2 bear a closure device 6, which in the present case comprises in each case four hydraulically driven closure cylinders 7. As shown in figure 4, the handling units 1, 10 are in each case connected to a drive device 17, by means of which they can be moved in the horizontal direction along a guide rail 18 and in the vertical direction. As a result of movement in the vertical direction, the frame 2 is placed onto a closed permanent mold 3 which is in a standing position, so that this mold is received with a small degree of play in the receiving shaft 35. It is fixed by the closure cylinders 7, which engage in the cutouts 8 in the coupling element 4. The travel of the closure cylinders 7 which is required for the fixing operation is very low, at a few millimeters (approx. 10 - 20 ram) . The first handling unit 1 does not have further movable parts, and consequently it can be produced with little structural outlay. The closure device 6 holds the closed permanent mold 3 inside the first handling unit 1 and holds it together during the casting operation.
The second handling unit 10 shown in figures 3a,b is suitable for conveying the open permanent mold with permanent-mold halves 3a, 3b which are at a distance from one another and aligned parallel to one another. It also comprises a U-shaped frame 11, the side walls 11a, lib of which are at a greater distance than the frame 2 of the first handling unit 1. Each side wall 11a, lib comprises a holding device 12, which in the

present case comprises holding elements 13, which interact with the pins 15 of the coupling elements 4, and holding cylinders 14, which interact with the cutouts 8. The permanent-mold halves 3a, 3b are held inside the second handling unit 10 by the holding device 12. The permanent mold is received as a result of the second handling unit 10 being placed from above onto the open permanent mold 3, which is standing upright, and then the holding cylinders 14 being moved. Other gripper mechanisms are possible as well as closure cylinders. In this case too, as in the first handling unit 1, there are no movable parts apart from the closure cylinders.
Figure 4 shows a preferred structure of the low-pressure die casting installation according to the invention as a linear arrangement. A casting station 19 and further working stations, in this case a core-insertion station 20, a removal station 21, a permanent-mold exchange station 22, a cleaning station 23 and a graphitizing station 24, are arranged along a straight line at preferably regular intervals. Between the casting station 19 and the core-insertion station 20 there is a waiting position 22'; the area above the permanent-mold exchange station 22 may also be used as a waiting position if there is not currently a permanent mold being exchanged. The left-hand part of the drawing shows the casting station 19 in a side view, rotated through 90°. The casting installation has a first handling unit 1 and two second handling units 10, 10', which are in each case connected to a drive device 17, which moves the handling units 1, 10, 10' along a linear guide rail 18 and, moreover, allows the height of the handling units to be adjusted. The handling units 1, 10, 10' can be displaced independently of one another. Their movement is controlled by a control device (not shown). Since the permanent molds are not fixedly connected to a specific handling unit, it is advantageously also possible for

three handling units to be used in the present linear arrangement. This considerably increases the cycle time of the installation compared to known installations.
One example of the movement of the permanent molds is illustrated in figures 11a,b. According to this example, the first handling unit 1 receives a closed permanent mold at the core-insertion station and moves it to the casting station 19 and then to the removal station 21. The closed permanent mold is transferred to the removal station 21, where it is opened, after which the casting is removed. During this time, the first-handling unit is already moving back to the core-insertion station in order to pick up a new permanent mold. The emptied permanent mold is picked up by the second handling unit 10 at the removal station 21 and, in the open state, is conveyed to the cleaning station 23 and transferred to the latter. After this transfer, the second handling unit 10 moves to the waiting position 22'. Finally, the cleaned permanent mold is picked up from the cleaning station 23 by the further second handling unit 10' and moved into the graphitizing station 24, where it remains on the further second handling unit 10' during the graphitizing. Then, it is moved to the core-insertion station 20, where the cycle begins again. The movements of the other two handling units which are carried out during this period can be found in figure 11a. Overall, it is possible to operate with three permanent molds synchronously, and it is possible to achieve cycle times of the installation in ' the region of 40-60 seconds. Since each permanent mold returns to the casting station 19 after three times the cycle time, no additional heating steps are required in order to keep the permanent mold at the desired temperature. The temperature of the permanent mold is measured and is kept constant by means of the washing or spraying time.
Figures 5-10 diagrammatically depict the structure of

the individual working stations, which in the text which follows are explained only where they differ from the structure of known stations. The structure of the casting station 19 shown in figure 5, with an induction furnace, corresponds to the prior art. The permanent mold is placed onto the riser 25 of the furnace by means of the first handling unit 1, which also applies the closure force required to close the permanent-mold halves 3a, 3b.
The core-insertion station 20 shown in figures 6a-b comprises a carriage 27 which can move transversely to-the direction of the guide rail 18 (figure 4) and to which an opening and closing device 26 is connected in such a manner that it can pivot about a horizontal axis. In the lying state (left-hand part of figure 6a), the opening and closing device can receive a permanent mold 3 which is presented in open form. The permanent mold is gripped by the opening and closing device 26 at its coupling elements 4. This is diagrammatically indicated in figures 6c-d: the permanent mold 3 is placed from above onto holding cylinders 14' which engage in lower cutouts 8 in the plate 5. Then, closure cylinders 7' move into lateral cutouts 8 in the plate 5, so that the latter is clamped. As a result of the opening and closing device 26 being pivoted through 90° (right-hand part of figure 6a), the permanent-mold halves 3a, 3b move into a horizontal position, so that the sand core can be inserted manually. The permanent mold 3 is finally closed and the opening and closing device is pivoted back into the lying position. The first handling unit 1 can pick up the closed permanent mold 3 in this state. Figure 6b shows the view of the core-insertion station which is sketched in figure 4, while figure 6a shows a view which is rotated through 90° with respect to this view.
The removal station 21 in figure 7 receives a closed permanent mold from the first handling station 1, and

opens it by means of an internal opening and closing device 26', so that the casting 28 can be ejected and removed using an ejector device. The permanent mold is then picked up in the open state.
An open permanent mold is transferred by a second handling unit 10 to the cleaning station which is outlined in figure 8 and has, in a housing 30, a suitable receiving means for the open permanent mold. The permanent mold is blasted or washed in a programmed manner. Then, the permanent mold is picked up by the further second handling unit 10' and moved to the graphitizing station 24 shown in figure 9, where it is lowered together with the handling unit 10', wash is sprayed in by a spraying unit 31 and the permanent mold is then raised again.
The permanent-mold exchange station 22 shown in figure 10 comprises a carriage 32 for carrying away a permanent mold which is to be exchanged and a carriage 33 for bringing in a new, preheated permanent mold. The carriages can move transversely with respect to the direction of the guide rail 18 (figure 4) . After a permanent mold which is to be exchanged has been deposited, the carriage 32 is moved sideways, so that the carriage 33 adopts the position which was originally held by the carriage 32, and the permanent-mold halves 3a, 3b are taken hold of in the open state.
Figure 12 shows a plan view of a low-pressure die casting installation according to the second variant of the invention, having a casting station 19, a removal and cleaning station 21/23, a permanent-mold exchange station 22, a cooling and wash station with core-insertion station 20 and a gripping and conveying system for moving the permanent molds. The gripping and conveying system comprises three handling units, which are moved along guide rails 18 arranged in the shape of

a triangle. The permanent molds 3 are shown in figs la-e, and the individual stations are shown in figs. IS¬IS.
Figs. 13a,b respectively show a side view and a plan view of a casting station 19 which is known per se and has a clamping unit 43. The clamping unit 43 comprises a rectangular, continuous frame 43a which, in its interior, has receiving elements 44 for receiving the coupling elements 4 of the permanent mold 3. The permanent mold 3 is introduced into the clamping unit 4 3 from above. In addition, clamping elements, which clamp the permanent mold 3 in the clamping unit 43 after it has been introduced, may be provided for the purpose of holding the permanent mold 3. The clamping unit 43 is secured to a vertically oriented rotary column 45 and can be pivoted about a vertical axis and also displaced in the vertical direction.
Figs. 14a-c show a removal and cleaning station 21/23 in a view from the side, perpendicular to the conveying direction (fig. 14a), from above (fig. 14b) and from the side in the conveying direction (fig. 14c). An opening and closing device 26, which is accessible to permanent molds 3 from above, is present. The opening and closing device 26 has holding elements 13, which likewise engage on the lateral plates 5 of the coupling elements 4 of the permanent molds 3. The distance between the holding elements 13, as seen in the conveying direction, is in this case variable, so that the two permanent-mold halves 3a, ' 3b can be pulled apart for removal of the casting and for cleaning (dashed illustration of the permanent-mold half 3b'). The opening and closing movement of the receiving unit 26 is brought about by cylinders 46. Guide rods 27 are used to guide the holding elements 13 in the horizontal direction. An ejector cylinder 48 is used to move an ejector plate 42, which is shown in more detail in figs. Ic-d and is used to release the finished casting

28 from the die, so that they can be picked up by a removal unit 51. After removal, a cleaning nozzle 29 is moved along the open permanent-mold parts 3a, 3b. The movement of the nozzle 29 can be controlled as a function of the casting die. The station also has a blasting unit 49.
Figs. 15a,b show a cooling and wash station having a core-insertion station in a side view and plan view, respectively. The permanent mold 3 is located in an opening and closing device 26'. The holding elements 13 of this device are substantially designed in the same way as those of the casting station 19 or cleaning station and once again engage on the coupling elements 4 of the permanent-mold halves 3a, 3b. The holding elements 13 move apart in order to open the permanent mold 3 (as shown in dashed lines) and pivot about horizontal axes Dl, Dl', in order for the permanent-mold halves 3a, 3b to be dipped in the cooling and wash bath 35. After pivoting back into the starting position with vertical permanent-mold halves 3a, 3b, the entire opening and closing device 26' pivots about a further horizontal axis D2 (further position illustrated in dashed lines). In this position, the cores are placed onto the lower permanent-mold half 3a, the permanent mold 3 is closed, the opening and closing device 26' is pivoted back and the permanent mold 3 is removed in the vertical direction by the gripping and conveying system.
Figs. 16a-c show the way in which' a permanent mold according to the invention is coupled to a handling unit which can be used for the second variant of the invention and for closed conveying in the first variant of the invention. The handling unit comprises a horizontal plate 53, on the underside of which holding elements 13' are arranged, the clear width between which elements is variable. They have a protuberance which engages in a corresponding notch in the pins 15

of the coupling elements 4. In this way, the permanent molds are fixed in both the horizontal direction and the vertical direction and are kept closed during conveying.

WE CLAIM:
1. A low-pressure die casting installation having at least one casting station (19), at least one further working station (20, 21, 22, 23, 24) and at least one handling unit (1, 10, 10') for conveying a permanent mold (3) which comprises two permanent-mold halves (3a, 3b), characterized in that at least one first handling unit (1) of a first design is present, which is suitable for conveying a closed permanent mold (3) without having means to open the mold, that at least one second handling unit (10, 10') of a second design is present, which is suitable for conveying an open permanent mold (3) and that at least one opening and closing device (26, 26') is present-
2. The low-pressure die casting installation as claimed in claim 1, wherein the first handling unit (1) is arranged in such a manner that it is able to convey a closed permanent mold (3) from and to the casting station (19), and wherein the second handling unit (10, 10') is arranged in such a manner that it is able to convey an open permanent mold (3) from and to the further working station (20, 21, 22, 23, 24).
3. The low-pressure die casting installation as claimed in claim 1 or 2, wherein the first handling unit (1) has a receiving shaft (35) and a closure mechanism (6), the cross section of the receiving shaft (35) being matched to the cross section of a closed permanent mold (3), in such a manner that the receiving shaft (35) is capable to receive the permanent mold (3) and the closure mechanism (6) being able to press the permanent- mold halves (3a, 3b) of a permanent mold (3) which has been received in the receiving shaft (35) toward one another.

4. The low-pressure die casting installation as claimed in claim 3, wherein the first handling unit (1) contains only fixed parts with the exception of the closure mechanism (6).
5. The low-pressure die casting installation as claimed in claim 3 or 4, wherein the closure mechanism (6) comprises at least one hydraulically operated closure cylinder (7).
6. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein the second handling unit (10, 10') has two holding devices (12) , which are each used to hold a permanent-mold half (3a, 3b), in such a manner that the permanent-mold halves (3 a, 3 b) are at a distance from one another and are preferably oriented parallel to one another.
7. The low-pressure die casting installation as claimed in claim 6, wherein the holding device (12) comprises a gripper mechanism, which is used to take hold of the permanent-mold halves (3a, 3b).
8. The low-pressure die casting installation as claimed in claim 6 or 7, wherein second handling unit (10, 10') comprises only fixed parts with the exception of the holding device (12).
9. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein the handling units (1, 10, 10') are forceable independently of one another.

10. The low-pressure die casting installation as claimed any in one of the preceding claims, wherein at least each of a core-insertion station (20) and a removal station (21) has an opening and closing device (26, 26') which is able to receive a permanent mold and to open and close the mold.
11. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein at least one handling unit (1) of the first design and at least two handling units (10, 10') of the second design are present.
12. A low-pressure die casting installation having at least one casting station (19), at least one further working station (19, 20, 21, 22, 23, 24), and at least one handling unit is capable to receive the mold (3) and to convey the mold between the casting station and the further working station characterized in that the casting station (19) is assigned a clamping unit with a frame (43a) for receiving a permanent mold (3) which has coupling elements (4), the closed mold (3) is insertable into the frame (43a) and is clamped therein and the clamping unit (43) is capable to hold permanent-mold halves (3a, 3b) together during casting, and that the handling unit is capable to receive the permanent mold (3) by engaging on the coupling elements (4).
13. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein set of permanent molds (3) each comprising a base body (9, 9'), and coupling elements (4), which are connected thereto and are arranged in such a manner that the spatial dimensions of the set of permanent molds (3), at least in one spatial direction, are independent of the size of their base bodies (9, 9').

14. The low-pressure die casting installation as claimed in claim 13, wherein each permanent mold half (3a, 3b) is assigned at least one coupling element (4) of a predetermined shape and size, and wherein the spatial position of the coupling elements (4) relative to one another is independent of the size of the base body (9, 9').
15. The low-pressure die casting installation as claimed in any one of the preceding claims, wherein the following further working stations are present: a core-insertion station (20), a removal station (21), a cleaning station (23) and a graphitizing station (24).
16. The low-pressure die casting installation as claimed in claim 13 or 14, wherein the base body (9, 9') is cuboidal and is capable of being split into two halves, and the coupling elements (4) are plates (5), struts or other coupling parts which are arranged parallel to one another laterally with respect to the base body (9, 9'), are connected to the base body by means of pins (34) and on which a handling unit engages, the plates (5), struts or other coupling parts having the same shape and being at the same distance from one another irrespective of the size of the base body (9, 9').
17. The low-pressure die casting installation as claimed in claim 13, 14, or 16 wherein the permanent mold (3) has a locking system for holding the two permanent-mold halves (3a, 3b) together.
18. The low-pressure die casting installation as claimed in claim 13, 14, 16 or 17 wherein the permanent mold (3) has a coding (39), which is preferably mechanical or electronic.

19. A method for operating the low-pressure die casting installation as claimed in any one of claims 1-11, in which the first handling unit (1) conveys a permanent mold (3) in the closed state from a core-insertion station (20) to the casting station (19), holds it closed during the casting and, after the casting, transfers it in the closed state to a removal station (21), in which the permanent ipold (3) is opened, and in which the second handling unit (10, 10') picks up the open permanent mold ( from the removal station (21) and conveys it in the open state to a further working station (22, 23, 24).
20. A method for operating the low-pressure die casting installation as claimed in claim 12, in which the at least one handling unit introduces the mold (3) into or picks up the mold (3) from the clamping unit (43).

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Patent Number

225092

Indian Patent Application Number

454/MAS/2002

PG Journal Number

49/2008

Publication Date

05-Dec-2008

Grant Date

30-Oct-2008

Date of Filing

14-Jun-2002

Name of Patentee

KWC AG

Applicant Address

CH-5726 UNTERKULM,

Inventors:

#	Inventor's Name	Inventor's Address
1	HASSIG HARRY	SCHLOSSACKERRING 1, CH-5723 TEUFENTHAL,

PCT International Classification Number

B22D18/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	01 114 553.9	2001-06-18	EUROPEAN UNION