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 discharge 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 assure 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.
It has come to light that the combustion process and the discharge of the propellant into the airbag cause injuries. In a large percentage of these injuries the cause lies in the fact that at different points the propellant emerges with varying intensity—that is, not with the desired and targeted intensity—at the respective discharge apertures. It has even occurred that the combustion chambers have been ruptured due to the pressure of the propellant.
The object of the present invention is to guarantee that the propellant will exit as uniformly as possible—i.e., exit in a controlled manner—from the corresponding discharge 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 discharge 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 discharge 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 discharge 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 discharge 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 constructed in the shape of a circular ring and that the outer contour is constructed so as to be elliptical. Thus, the larger axis of the ellipse extends through the transition aperture up to the opposite area, in which—or on both sides of which—there are the discharge apertures. However, both contours—i.e., the inside cross section and/or the outer contour—may be constructed correspondingly elliptical.
Both the barrel shaped body and the ignition chamber may be manufactured 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 regard, in accordance with the rest of the invention, at least individual steps of the process steps listed in the description of the figures, may be suitable to produce the base bodies 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. It has been found that in many cases the peeling behavior was not adequate or that there were relatively large scatterings in the peel strength. In particular, it was shown that the weld peeled layer by layer. The reason was deemed to lie in the stretching of the material that was carried out to produce the sleeve and/or barrel shaped base body, 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 in which a high energy density is generated on relatively small areas has proven to be especially economical), 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 (i.e., temper) around the spot to be welded prior to the welding process. However, it has been found that this tempering offers only a partial improvement and that weld strength variations are still relatively large.
In addition, it has been proposed to carry out a second pulse—a so-called post impulse—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 (i.e. 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 parts in general that are connected together by a welding process.
Accordingly, 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 aspect of the invention 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 due to prior stretching is tempered or rather annealed at least in the area of the weld zone, in order to relieve stress at least at that zone.
As a result of this heating process directly before the welding process, during which the part still has a certain thermal capacity or amount of stored heat 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 retarded, 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 advantageous to provide heating up to a value, at which there is no oxidation or rather no tempering color arises that may have a deleterious effect on the subsequent welding operation.
Furthermore, it is advantageous to configure 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 advantageously be carried out by inductive heating, but also by 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 also may be carried out in a continuous furnace in front of the welding station.
The invention will be described in further detail hereinafter with reference to illustrative preferred embodiments shown in the accompanying drawing figures, in which:
a is a sectional view of the workpiece taken along line VIIIa-VIIIa of
b is a sectional view of the workpiece taken along line VIIIb-VIIIb of
After the ignition chamber 3 is filled with the igniting medium and the hollow body 8 of the combustion chamber is filled with the propellant, the ignition chamber 3 is closed by means of a threaded connection, and the end face 9 of the combustion chamber is closed by welding on a cover.
In order to produce the sleeve shaped base body of the combustion chamber, the blank 10 as shown in
In a subsequent working or process step, setting or centering is carried out to introduce or create a concentric recess 11 as shown in
In the working step, according to
In the working step, depicted in
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. Due to this heat treatment a specific strength is also achieved with respect to the finished component; or rather through a suitable heat treatment and the degree of deformation in the subsequent processing step(s), the final strength of the component may be affected.
In the working step, according to
In a subsequent process step, a rough turning operation takes place, during which the region 13a shown in
In the step according to
In the working step, depicted in
In a further step according to
In another process step, as shown in
The foregoing description and examples have been set forth merely to illustrate the invention and are not intended to be limiting. Since modifications of the described embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed broadly to include all variations within the scope of the appended claims and equivalents thereof.
Number | Date | Country | Kind |
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10 2005 043.767.2 | Sep 2005 | DE | national |
10 2006 008 581.7 | Feb 2006 | DE | national |
10 2006 034 285.2 | Jul 2006 | DE | national |
This application is a continuation of international patent application no. PCT/DE2006/001579, filed Sep. 11, 2006, designating the United States of America and published in German on Mar. 22, 2007 as WO 2007/031057, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application nos. DE 10 2005 043 767.2, filed Sep. 13, 2005; DE 10 2006 008 581.7, filed Feb. 24, 2007, and DE 10 2006 034 285.2, filed Jul. 21, 2006.
Number | Date | Country | |
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Parent | PCT/DE2006/001579 | Sep 2006 | US |
Child | 12047424 | US |