|Title of Invention||
|Abstract||The invention relates to a combustion chamber (1) and to the method for the production thereof.|
|Full Text||FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13)
1.TITLE OF INVENTION
COMBUSTION CHAMBER AND METHOD FOR THE PRODUCTION
NEUMAYER TEKFOR HOLDING GMBH
7 7 756 HAUSACH
3.PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -
ENGLISH TRANSLATION VARIFICATION
CERTIFICATE u/r. 20(3)(b)
I, Mr. HIRAL CHANDRAKANT JOSHI, an authorized agent for the applicant, NEUMAYER TEKFOR HOLDING GMBH do hereby verify that the content of English translated complete specification filed in pursuance of PCT International application No. PCT/DE2006/001579 thereof is correct and complete.
The invention relates to a barrel shaped hollow body with a mounted ignition chamber with a connecting channel between the barrel shaped body and the ignition chamber. In this case the ignition chamber serves to receive an igniting medium, which following ignition enters into the combustion chamber and ignites the propellant, which is located in said combustion chamber. Then the propellant flows through the exit apertures, which are affixed in a suitable manner in the barrel shaped body on the side that is situated opposite the ignition chamber.
This type of chamber must meet stringent requirements in terms of accuracy, in order to guarantee that the propellant will exit in as controlled a manner as possible into the airbag. This type of barrel shaped body is produced by cutting tubes to appropriate length and then sealing on both sides.
The object of the present invention is to guarantee that the propellant will exit as uniformly as possible — that is, exit in a targeted manner—from the corresponding exit apertures of the combustion chamber. In addition, the invention makes possible a production that is as economical as possible, and the invention achieves a high quality, in particular strength, which is reliable with regard to the process.
This object is achieved by the invention in that the wall strength of the barrel shaped body is stronger in at least approximately the area of the outflow apertures and in the area of the transition aperture than in the rest of the area. This feature may be achieved, for example, by constructing the barrel shaped body so as to be reinforced in the area of the outflow apertures and in the area, in which the ignition chamber is mounted. For example, said barrel shaped body is reinforced in a manner analogous to an eyelet or by providing said barrel shaped body with a greater material thickness over at least approximately the length, over which the exit apertures are arranged and/or the opposing area —thus, the area, in which the ignition chamber is mounted— in the barrel shaped body, over at least approximately the entire length. This may be done, for example, by constructing the inside cross section of the barrel shaped body
elliptical and by constructing the outer contour circular. As a result, the shorter axis of the ellipse extends at least approximately through the area of the transition aperture and reaches up to the opposite area, on which or on both sides of which the exit apertures are suitably arranged mirror-like over the length of the barrel shaped body.
The configuration may also be laid out in such a manner that the inside cross section is designed in the shape of a circular ring and that the outer contour is designed so as to be elliptical. Thus, the larger axis of the ellipse runs through the transition aperture up to the opposite area, in which—or on both sides of which—there are the exit apertures. However, both contours—thus, the inside cross section and/or the outer contour— may be designed correspondingly elliptical.
Both the barrel shaped body and the ignition chamber may be constructed especially advantageously and economically, if a sleeve shaped base body of the barrel shaped body and/or a similarly sleeve shaped base body of the ignition chamber is/ are produced from a solid blank as a cold extruded part.
In this respect at least individual steps of the process steps, cited in the description with regard to the figures, may be suited, according to the rest of the invention, in an especially optimal manner.
Such components require a high and—above all—also uniform strength. For this reason, peel tests are carried out, inter alia, at random, in order to test the strength of the welded joint. During production of the sleeve and/or barrel shaped base body, a stretching of the material that was carried out as a result of which a longitudinally oriented laminar structure, which extends in the axial direction, and/or stretched grains are produced.
When welding on the parts, in particular during resistance welding (where capacitor discharge welding has proven to be especially economical—where, therefore, a high
energy density is generated on relatively small areas), it can happen that during the peel test a layer by layer peeling takes place at the weld.
In order to remedy these drawbacks, it has already been proposed to heat—that is, temper—around the spot to be welded prior to the welding process. However, it has been demonstrated that this tempering offers only a partial improvement and that scatterings are still relatively large.
In addition, it has been proposed to carry out a second pulse—a so-called after pulse— following the welding process.
As a result, there was some improvement with regard to the tempering, but at the same time the cycling times of the machine increase significantly.
The object of an additional inventive idea is to avoid the above described drawbacks, in order to obtain a high welding quality—that is, high peel strength at low cost—in not only this type of component but also in others. This part of the invention relates not only to the parts that are described here and/or the method for producing the parts, which are described here, but also relates to parts and/or methods for producing in general parts that are connected together by means of a welding process.
Against this background, this inventive section relates to a method for producing products, where one component is welded together to another component. Of these two components at least one exhibits at least zones, which were subjected to a material stretching. This inventive section is characterized in that prior to the welding process at least one of the components is heated in at least the area of the weld to be formed; and that the welding process takes place in the heated state. Therefore, it may be especially advantageous, if, in addition, prior to the welding process the workpiece that exhibits zones having laminar structure owing to prior stretching is tempered or
rather annealed at least in the area of the weld zone, in order to stress relieve at least that zone.
As a result of this heating process directly before the welding process, during which the part still has a defined thermal capacity or rather a heat accumulator amount even during the welding process, when the part cools down, the effect of the ambient temperature on the weld or rather the immediate environment is decreased. That is, a certain thermal capacity remains over a prolonged period of time, so that the cooling process is retarded and enhanced internal stresses are avoided. In this way very high and stable peel strengths are achieved. Therefore, the critical cooling rate shall be decelerated, and the formation of martensite shall be at least reduced.
In this respect it may be advantageous if only one of the components is heated; and, moreover, it may be especially advantageous if the component as a whole is heated. It may be advantageous if the heated component is the component that has the smaller mass. However, in other cases it may also be advantageous to heat the component that has the higher heat dissipation in the weld zone.
In this respect it may be especially practical to heat up to a value that avoids or reduces the formation of martensite during the cooling down process. Therefore, it is appropriate to provide heating up to a value, at which there is no oxidation or rather no tempering color that may have a deleterious effect on the following welding operating.
Furthermore, it is practical to design the heating process in such a manner that with respect to the formation of martensite during the cooling process a critical cooling rate is undershot.
This additional heating of the weld zone or at least one of the components prior to the welding process may be carried out advantageously by means of not only inductive
heating but also infrared heating in a process prior to the actual welding process, which does not have a negative impact on the machine cycling times, which are necessary for the welding process.
It is advantageous for the heating to be carried out during the feed cycle in the welding tool.
However, heating may also be carried out in a continuous furnace in front of the welding station.
The invention is explained in detail below with reference to the Figures 1 to 10.
Figure 1 depicts the barrel shaped body of the combustion chamber with the ignition chamber, welded to said body.
Figures 2 to 10 depict the individual process steps for producing such a combustion chamber.
Figure 1 shows that the combustion chamber 1 consists of a barrel shaped or rather sleeve shaped base body 2 with an ignition chamber 3, which is welded to said base body. The ignition chamber 3 is accommodated by way of a neck 4 in a recess 5 of the sleeve body 2 and welded into this area. In addition, the ignition chamber 3 has a transition aperture 6 and exit apertures 7 on the opposite side.
After the ignition chamber 3 is filled with the igniting mediums and the hollow body 8 of the combustion chamber is filled with the propellant, the ignition chamber 3 is closed by means of a screw connection, and the face side 9 of the combustion chamber is closed by welding on a lid.
In order to produce the sleeve shaped base body of the combustion chamber, the blank 10 is cut to length, for example, sawed off, as depicted in Figure 2, from bar stock.
In a subsequent working or rather process step, the placing/centering is carried out, as depicted in Figure 3. In particular, a concentric notch 11 is cut that serves to center the extrusion punch for the subsequent working steps.
In the working step, according to Figure 4, the so-called "cupping (1)" takes place. In this case an extrusion punch is pushed into the centering recess (11); and at the same time the material runs axially upwards, and in particular along the extrusion punch— thus, a so-called "backward cup extrusion." Therefore, the bottom, marked 12 in Figure 3, is decreased; and the bottom 12a is formed, as depicted in Figure 4.
In the working step, depicted in Figure 5, a "cupping 2" takes place. In this case the bottom 12a of Figure 4 is reduced; and the bottom 12b, which correlates at least approximately to the final dimension, is produced. In this working step the material of the bottom 12a is reduced; and the material is displaced backwards along an inserted extrusion punch.
Then a heat treatment is carried out. In particular, heating ensues up to a temperature so that at least approximately the initial microstructure is produced again. Owing to this heat treatment a defined strength is also achieved on the finished component; or rather through a suitable heat treatment and the degree of deformation in the next processing step(s), the final strength of the component may be affected.
In the working step, according to Figure 6, the bottom 12c is ironed and extruded. Hence, even the conical area 13a—a so-called support area—is formed. Moreover, the tubular or rather sleeve shaped area 13, depicted in Figure 5, is elongated; and a sleeve shaped area 14 is produced. In this working step the oval and/or elliptical internal contour 15 is also produced (see also Figure 8a).
In a subsequent process step, according to Figure 7, a rough turning operation takes place, during which the region 13 is dressed, according to Figure 6.
In the step, according to Figures 8, 8a and 8b, where the latter two depict a sectional view along the lines Villa - Villa and VIIIb - VIIIb of Figure 8, the so-called punching takes place—that is, the incorporation of the apertures 16 for accommodating the ignition chamber and the punching of the outflow apertures 7, 7a in the opposite area of the aperture 16. In so doing, the apertures 16 as well as 7 and 7a are disposed opposite each other and/or the apertures 7, 7a are symmetrical to the central plane or central axis 17, which runs through the aperture 16 and between the two boreholes 7, 7a. The elliptical configuration 15 is laid out in such a manner that the elliptical axis a is shorter than the elliptical axis b. Thus, since the outer contour 15a exhibits the shape of a circular ring, the area of the recess 16 as well as 7 and 7a retains a greater material thickness.
In the working step, depicted in Figure 9, the receiving borehole 16 is drilled or rather sunk, so that the result is a contour 16a at a relatively flat angle.
In another step, according to Figure 10, the receiving contour 18 is turned for a lid, which is welded after the filling operation.
In another process step, as shown in Figure 1, the ignition chamber 3 is welded onto the sunk contour 16a; and a weld bead 19 is formed. In this case it is especially advantageous to carry out the welding process, as described in the section preceding the description of the figures, in that the ignition chamber 3 is heated prior to the welding process, in particular a resistance welding process, like a capacitor discharge welding process, and that the welding process takes place in the heated state of the ignition chamber. In this case the welding current may be introduced over the ignition chamber and may be carried away over the sleeve body 2.
1. Combustion chamber, in particular for airbags, comprising a barrel shaped body, on which is mounted an ignition chamber; and between the ignition chamber and the barrel shaped body there is a transition aperture, with outflow apertures, which are situated at least approximately opposite the transition aperture, in the barrel shaped body, characterized in that the wall strength of the barrel shaped body is greater in the region of the outflow apertures and in the region of the transition aperture and/or the attachment region of the ignition chamber than in the rest of the region.
2. Combustion chamber, in particular as claimed in claim 1, characterized in that the outside diameter and/or the inside diameter of the barrel shaped body exhibit(s) an elliptical cross section in such a manner that the greater wall strength is provided along the exit apertures and in the region of the transition aperture and/or the receiving aperture for the ignition chamber at least approximately along the longitudinal reach of the barrel shaped base body.
3. Combustion chamber, in particular as claimed in any one of the claims 1 or 2, characterized in that the barrel shaped body is made and/or can be made, as a cold extruded part, from a solid blank as a sleeve shaped base body.
4. Method for producing a sleeve shaped base body for the barrel shaped body, as claimed in any one of the claims 1 to 3, characterized by at least any one of the process steps, listed below:
a) cutting to length of a workpiece blank from a bar stock
b) placing/centering and affixing a depression shaped recess, at least in essence by cold extrusion
c) subsequent cupping by means of an extrusion punch, which penetrates deeper into the substance blank, to form a bottom by cold extrusion, decreasing the bottom to a bottom
d) additional cupping, during which the bottom is reduced to a bottom; and the cup shaped structure is enlarged, according to step c), to form a deeper cup shape by cold extrusion
e) carrying out a heat treatment; heating to a temperature so that at least approximately the initial microstructure is produced again.
f) subsequent ironing to form an elongated sleeve shaped region and molding of the bottom, during which an area, which faces away from the bottom, is extruded conically, whereas one part of this conical area and the rest of the area is stretched; in this or a subsequent step the elliptical cross sectional contour (which is mentioned in the introductory part of the description) in the inside diameter and/or in the outside diameter is produced,
g) dressing of the conical area, according to step f)
h) punching the outflow apertures, expediently in the same tool; punching
the receiving borehole for the ignition chamber
i) drilling/ sinking the receiving borehole for the ignition chamber
j) turning the aperture side and forming a weld edge for welding the lid
k) attaching the ignition chamber, preferably by means of capacitor
5. Method for producing products, like a combustion chamber, in particular as claimed in any one of the preceding claims, where one component, like an ignition chamber, is welded together to another component, like a sleeve or barrel shaped base body, of which at least one exhibits at least zones, which were subjected to a material stretching, by means of a welding process, during which a high energy density is generated on relatively small surfaces, as by means of resistance welding,
characterized in that prior to the welding process at least one of the components is heated in at least the area of the weld to be formed; and the welding process takes place in the heated state.
Method, in particular as claimed in claim 5, characterized in that one of the components is heated as a whole.
Method, in particular as claimed in claim 5 or 6, characterized in that the component that has the smaller mass is heated.
Method, in particular as claimed in any one of the claims 5 to 7, characterized in that the component that has the higher heat dissipation in the weld zone is heated.
Method, in particular as claimed in any one of the claims 5 to 8, characterized by heating up to a value that at least reduces the formation of martensite during the cooling down process.
Method, in particular as claimed in any one of the claims 1 to 9, characterized by heating to a value below the oxidation limit, in particular avoiding the formation of tempering colors.
Method, in particular as claimed in any one of the claims 5 to 10, characterized by heating with respect to the formation of martensite to a value that falls below a critical cooling rate.
Method, as claimed in any one of the claims 5 to 11, characterized by heating by means of inductive heating prior to the welding process.
13. Method, as claimed in any one of the claims 5 to 12, characterized by heating in a continuous furnace in front of the welding station.
14. Method, as claimed in any one of the claims 5 to 13, characterized by heating during the feed cycle into the welding tool.
15. Method, in particular as claimed in any one of the claims 1 to 14, characterized in that one of the components in the region of the weld to be formed is tempered prior to the welding process.
The invention relates to a combustion chamber (1) and to the method for the production thereof.
The Controller of Patents,
The Patent Office,
- 13 -
|Indian Patent Application Number||687/MUMNP/2008|
|PG Journal Number||28/2013|
|Date of Filing||09-Apr-2008|
|Name of Patentee||NEUMAYER TEKFOR HOLDING GMBH|
|Applicant Address||WILHELM-ZANGEN-STR. 9, 77756 HAUSACH,|
|PCT International Classification Number||B21C23/20|
|PCT International Application Number||PCT/DE2006/001579|
|PCT International Filing date||2006-09-11|