Title of Invention

A METHOD FOR MANUFACTURING A MOULD

Abstract

(57) Abstract: There are disclosed a method and/apparatus for manufacturing a mouldfor casting a large-size product having a complex shape. The method for manufacturing a mould includes the steps of preparing a block in which powder granular material is cured, and processing the block by an automatic processing machine to define amoulding surface in the block according to a pre-installed program. PRICE: THIRTY RUPEES

Full Text

The present invention relates to a method and an apparatus for manufacturing amouldfor casting a metal product, more particularly to a method and apparatus for manufacturing a mould without using a prototype model to be produced. Description of the Related Art: The conventional process for manufacturing a cast metal product having a complex shape includes a step of preparing mould) a prototype model (core / having the same shape as the product mould to be produced and a step of manufacturing a / using the prototype model. The prototype model, which may be made of wood, metal or resin, is usually made by using a precision processing machine because of its complex shape and requirement for a high degree mould) dimensional accuracy. Then the mould(cavity / for casting the products is manufactured by transferring the shape of the prototype model to a sandmould and then, solidifying the sand mould. After the shape of the prototype model is transferred mould, to the sand / the prototype model is removed from the sand mould . The sand model is removed from the prototype model by dividing it into a few pieces when the sand mould is made dividable, or, by mould heating it to burn or melt after providing the sand / material around the prototype model when the prototype model is made of wax or resin. In the above method, steps of manufacturing the prototype model and transferring the shape of the prototype model to the sand mouldcare necessary, which make the entire crocess complicated, and a reproducibility of the shape is relatively low. Particularly, when the prototype model is relatively large as well as of a complex shape, the prototype model made of wax or resin does not have a sufficient mechanical strength to deteriorate operational convenience and dimensional accuracy. When the sand mould is made dividabie, it is very difficult to remove the sand mould by dividing because its weight and dimension is large and may possibly cause chipping of details. 5UMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and apparatus for manufacturing a mould moulding for / a large-size product having a complex shape, whichmak.es the use of a prototype model of the cast product unnecessary, thereby reducing the necessary steps compared to the conventional nethod, and in which a high level of reproducibility of the shape can be achieved. Accordingly, the present invention provides a method for manufacturing a mould for moulding metal wherein comprising the steps of: providing at least two sand blocks, each of said at least two sand blocks, having a mating surface and exposed peripheral surfaces; preparing said sand blocks by solidifying the sand therein at a compressive strength ranging from 20 to 80 kg/cm2; directly processing each of said mating surfaces by an automatic processing machine to form t moulding surface thereon, said automatic processing machine controlling a machining tool in accordance with a pre-tostalled program; and combining said at least two sand blocks by mating said mating surfaces together thereby to define a moulding cavity therebetween for casting a desired product. According to a second aspect of the present invention, mould an apparatus for manufacturing a / comprises a processing table on which a block to be processed is placed, an automatic processing machine to process the block according to a pre-installed program, and an absorption pipe for absorbing powder particles generated during the processing, the absorption pipe having an opening to provided adjacent/a processed portion of the block. mould According to the present invention, since the y is directly produced by processing a sand block, a detailed and complicated shape can be processed on the block, and the conventional shape transferring step is not required. Therefore, the mouldproduced by the present invention makes it possible to moulding conduct a more precise . / process. Consequently, a product having a complicated shape can be cast with a high level of reproducibility and less cost. The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a schematic illustration showing an outline of the present invention; FIG. IB is a perspective view showing an apparatus for manufacturing amould of the present invention; FIG. 2A is a perspective view showing a sand block before being processed; FIG. 2B is a perspective view showing a lowermould; FIG. 2C is a perspective view showing an uppermould; and DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, a preferred embodiment of the present invention will now be described in detail, referring to the drawings. FIG. 1A is a schematic illustration showing an outline mould of a method and apparatus of manufacturing a ' / of the present invention. FIG. 1A shows a data inputting process where data mould regarding a three-dimensional shape and size of the. / is fed in a computer 1, and an automatic processing machine 2 controls its machine head provided with a machining tool in accordance with the inputted data and then processes the mould,This input process is carried out by a widely-used program, namely. Computer Aided Manufacturing (CAM). The data regarding the shape and size of the mould may be " fed by an operator or by using various devices or programs which has been developed and capable of directly or indirectly reading the data from a drawing of a model 3 or a model itself. The mould is designed in consideration of various factors such as solidification shrinkage or cutting stock for finish in addition to the design of the product cast by the mould. mould when the design of the / is conducted by using a program, namely, 5 Computer Aided Design (CAD) with display of an image of the mould the data of the CAD may be directly used as the data of the CAM. In this case, the step for inputting the data to CAM can be omitted. Also, when the product to be manufactured by casting itself is designed by using the CAD, the mouldean be automatically designed l6 at the same time, which can further shorten the time necessary for manufacturing the mould . FIG. IB is a perspective view showing an automatic processing machine 2 according to the present invention. The automatic processing machine 2 has a processing table 5 on which V5 a sand block. 4 to be processed is placed. Above the processing - table 5, a tool support portion 6 is provided to bridge over the processing table 5. The tool support portion 6 is provided with a machine head 8 movable in one or a few directions for supporting and driving a machining tool 7 such as a drill, an end mill or a 2/f milling cutter. The automatic processing machine 2 is also provided with a control device for controlling the movement of the machine head 8 and the rotation of the machining tool 7. The automatic processing machine 2 has one or more absorption pipes 9 connected to a vacuum pump {not shown) for absorbing and 2-5 exhausting sand or dust generated due to the processing of the block 4. The absorption pipe 9 may be preferably provided on the machine head 8 so as to move together so that the opening end of the absorption pipe 9 is always set close to the machining tool 7 processing the block 4, thus, securely exhausting the sand or dust. The mould may be produced by the above automatic processing machine in the following manner. In this example, two plate-like blocks 4 are prepared, and each of the confronting moulding faces are processed into a / surface. The blocks 4 are then mould mould combined to build up a / comprising a lower .. y 4a and an upper D.uld- 4b. The material for the block 4 is required to have, in addition to the usual properties required as a mouldmaterial, certain mechanical workability enough for preventing the occurrence of chipping during processing, though a strict specification is not necessary. According to the experimental tests held by the inventors, blocks 4 having a compressive strength larger than 2 0 kg/cm2 did not induce any problems. However, when the compressive strength of the block 4-was larger than 80 kg/cnr', the processing efficiency or the life of the tools 7 was lowered. Thus, the optimum range of the compressive strength of the block 4 is 40-60 kg/cnr". The sand material of the block 4 is preferably prepared to be finer than usual, when the processing efficiency and the life mould of the tools 7 is taken into consideration. When the / is used for casting a product having a high crack sensitivity, a block made mould of a special sand material should be used. A / generally called as a CO2 mould including water glass as a bond which is cured by gas, or a furan resinmould in which furan resin is cured by acid contained therein may preferably be used. At the corners of the confronting surfaces of the blocks 4, there are formed recesses 10a and projections 10b for positioning the blocks 4 to each other. The recesses 10a and the projections 10b may be formed at the time when the block 4 was manufactured or simultaneously when the moulding surface is processed on the block 4 by the automatic processing machine 2. The projections 10b can be also formed by preparing in advance a projection element having a shape in which two truncated corns are connected at their bottoms, and inserting the object into the recess 10a formed in the block 4. In this case, the entire surface of the block 4 does not have to be ground just because forming of the projections 10b is necessary. The processing of the surface of the block 4, which is placed on and positioned to the processing table 5, is carried out by the automatic processing machine 2 according to the program which was installed in advance. The automatic processing machine 2 may have a mechanism for automatically changing the machining tools 7 required in the processing. When such a mechanism is not provided in the automatic processing machine 2, the tools 7 are changed in order by an operator. After the mechanical processing for forming a cavity including a sprue for casting a metal, a surface treatment is conducted on the processed surface to strength the surface when it is necessary. Through the above process, the mould mould blocks 4 are processed into a lower / 4a and an upper / 4b mould shown in FIGS. 2B and 2C, respectively. The lower / 4a and the uppermould 4b are integrated to produce a mould by adhering or fastening after matching their mould in a surfaces by using the recesses 10a and projections 10b as positioning means. In this moulding mould example, the / surface of the upper / 4b is protruded from its matching surface. According to the method and apparatus for manufacturing a rnculcbf the present invention, the processing is conducted while absorbing the sand chips by the absorption pipe 9 opening close to the block 4 , which prevents the sand from entering into a space between the tool 7 and block 4 during the processing and damaging the processed surface. Also, since the absorption pipe 9 absorbs the sand dust during the processing, the operational environment is kept in good condition. In the present invention, since the block 4 can be processed based on the data regarding the shape and size of the mould- or the cast product fed - in a computer, it is usable for mass production system for the cast product, nevertheless, it is also suitable for a multi-product small quantity production. Also, since the data can easily be amended or combined by utilizing the CAD method, in is easy to incorporate moulding conditions or to respond to minor changes of a design. Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims. WE CLAIM: 1. A method for manufacturing a mould for moulding metal wherein comprising the steps of: providing at least two sand blocks, each of said at least two sand blocks, having a mating surface and exposed peripheral surfaces; preparing said sand blocks by solidifying the sand therein at a compressive strength ranging from 20 to 80 kg/cm2; directly processing each of said mating surfaces by an automatic processing machine to form a moulding surface thereon, said automatic processing machine controlling a machining tool in accordance with a pre-installed program; and combining said at least two sand blocks by mating said mating surfaces together thereby to define a moulding cavity therebetween for casting a desired product. 2. The method for manufacturing a mould according to claim 1, wherein data for processing said sand block is obtained based on a dimensional data of a product to be cast. 3. The method for manufacturing a mould according to claim 1, wherein a projection and a recess are provided on said mating surfaces of said sand blocks for relatively positioning the sand blocks to each other. 4. The method for manufacturing a mould according to claim 1, wherein a recess is provided on said mating surface of said sand blocks, and a positioning element is inserted into said recess for relatively positioning said sand blocks to each other. 5. The method for manufacturing a mould according to claim 1, wherein ssid at least two sand blocks are formed in a plate-like snipe. 6. A method for manufacturing a mould, substantially as herein described with reference to the accompanying drawings.

Documents:

2124-mas-1996 abstract.jpg

2124-mas-1996 abstract.pdf

2124-mas-1996 claims.pdf

2124-mas-1996 correspondence others.pdf

2124-mas-1996 correspondence po.pdf

2124-mas-1996 description (complete).pdf

2124-mas-1996 drawings.pdf

2124-mas-1996 form-2.pdf

2124-mas-1996 form-26.pdf

2124-mas-1996 form-4.pdf

2124-mas-1996 form-6.pdf

2124-mas-1996 form-9.pdf

2124-mas-1996 others.pdf

2124-mas-1996 petition.pdf