JP2007533461A - Method and apparatus for manufacturing workpieces by internal high pressure molding - Google Patents

Abstract

  The present invention relates to a method for simultaneously producing at least two separate workpieces (6, 7) by internal high pressure molding. According to the method, the blank is inserted into the forming tool (2), the inner wall (3) of the blank is provided with at least one separation gap (8), which separation gap comprises two negative molds (4, 5, 5). ), Respectively, extending over the entire circumference of the workpiece (6, 7) and defined by two spaced apart cutting edges (9, 10). During molding, the blank penetrates into the region of at least one separation gap (8) so that each of the cutting edges (9, 10) cuts out a section (15) between the two workpieces (6, 7). .

Description

  The invention relates to a method and apparatus for simultaneously producing at least two workpieces separated from each other by internal high-pressure molding or hydroforming, according to the preamble of the independent claim.

  The internal high-pressure molding method, also called hydroforming, uses a hollow cross-section material (blank), for example, a tube inserted into a molding tool, and the material is in close contact with the negative mold of the molding tool spaced away from it, resulting in a negative profile. Based on applying internal high pressure to the material by sealing both sides of the material. In this way, on the one hand, it is possible to produce a hollow body which can have a complex shape and on the other hand has a high strength, a thin wall thickness and thus a light weight. For economic reasons, it is advantageous to produce several workpieces simultaneously with one molding tool.

  Patent document 1 discloses a method and an apparatus of the kind mentioned at the beginning. In this specification, the blank is inserted into a molding tool having at least two negative molds and at least one separation gap for each of the workpieces on the inner wall. This separation gap is located between each two negative molds, extends across the entire circumferential direction of the workpiece and is defined by two spaced apart cutting edges. In each separation gap of the known device, a tool part is arranged which can be positioned with respect to the workpiece in the separation gap. In order to mold the material, the inner contour of the tool part terminates flush with the cutting edge, so that the tool part is embedded in the inner wall of the molding tool and therefore does not move so that the tool part is inside the molding tool. It is pushed toward. Molding of the forming tool material is done with a calibrated pressure selected so that the material in the negative mold is in full contact with the inner wall and therefore also in full contact with the inner contour of the tool part that closes the separation gap. After this shaping operation, a separation operation is performed, for which purpose the pressure in the hollow body is raised above the calibration pressure. While the tool part located in the separation gap still bears the calibration pressure, the tool part is now pushed outwards by a higher separation pressure. Only with this relative adjustment of the tool part the cutting edges are exposed, so that the part arranged between the cutting edges and thus between the two workpieces is cut out.

  Thus, the known device or the known method has two successive stages. In the first stage, the workpieces are molded from the raw material in a conventional manner and the workpieces are still integral with each other after molding. Next, in a subsequent second stage, the two workpieces are separated by releasing the cutting edge using a further increased internal pressure.

  The cost of providing a workpiece part that can withstand the calibration pressure and does not release the cutting edge until the separation pressure is high is relatively high in this case.

  In addition, US Pat. No. 6,057,089 discloses a method and apparatus for drilling a workpiece, where one side of the workpiece is exposed to a pressure medium under high pressure and the other side of the workpiece is Under the action of a punch guided in the tool, this punch releases the surrounding cutting edge formed in the tool, at which the wall is cut under the influence of elevated high pressure.

German Patent Invention No. 19716816C2 Specification German Patent Application Publication No. 19747607A1

  The invention relates to the problem of providing an improved embodiment, which can be produced more particularly cost-effectively, simultaneously producing at least two workpieces separated from each other by internal high-pressure molding or hydroforming.

  According to the invention, this problem is solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

  The present invention is based on the general idea of pre-positioning the cutting edges so that they are exposed during the forming of the material and forming so that the workpieces are separated simultaneously. Thus, in the method according to the invention, the separation of the workpiece takes place with the shaping. In this case, the present invention utilizes the unexpected knowledge that the part of the workpiece that closes the separation gap and forms the buried structure of the cutting edge is not necessary for forming the material. Therefore, in the forming tool according to the present invention, such a tool portion for closing the separation gap is omitted. This makes the forming tool structure simpler and more cost effective.

  According to a particularly advantageous development, the gap width of the separation gap is dimensioned so that the workpiece is separated at a calibration pressure at which the material comes into full contact with the negative inner wall. In this proposal, the present invention seeks in principle a different method of designing method parameters and forming tools. In a conventional two-stage procedure, a separation gap is provided in the molding tool and dimensioned so that a desired separation of at least two workpieces can thus be achieved by a corresponding increase in internal pressure. . For this purpose, the separation gap is closed by a suitable tool part for shaping the material. In this case, the holding force to position the workpiece part is the calibration required for proper forming of the material so that the workpiece part is not adjusted to the calibration pressure and the cutting edge is not exposed during molding. Selected based on pressure. Secondly, in the separating operation, such a high separating pressure is used so that the tool part can be pushed into the gap, the cutting edge can be exposed and the desired part between the two molded workpieces can be cut out. Is selected. In contrast to this, the gap width in the case of the present invention is based on the calibration pressure and, in particular, is chosen such that the part between the two workpieces is cut out simultaneously at the calibration pressure. That is, in the case of the present invention, the separation gap is dimensioned based on calibration pressure, not arbitrarily or based on geometric constraints due to negative tool positioning. Therefore, the positioning of the negative mold inside the molding tool depends on the determined separation gap, but not vice versa.

  Since the workpieces are already separated at the calibration pressure of the method according to the invention, the two-step method is omitted, and as a result, manufacturing is simplified overall.

  Important further features and advantages of the invention emerge from the dependent claims, from the drawings and from the description associated with the drawings.

  It goes without saying that the features described above and further described below can be used not only in the respective combinations specified, but also in other combinations or alone, without departing from the scope of the present invention.

  Preferred exemplary embodiments of the invention are shown in the drawings and are described in more detail below, in which the same reference numerals relate to the same or functionally the same or similar components.

  According to FIGS. 1 to 3, the molding and separating device 1 according to the invention comprises a molding tool 2 which is also shown in part with an inner wall 3 which is only partly shown in the figure. At least two negative molds 4 and 5 are formed on or in the inner wall 3, each of these negative molds producing a workpiece 6 or 7 according to an internal high pressure molding process or a hydroforming process, respectively. Used for. A separation gap 8 extending in the entire circumferential direction of the workpieces 6 and 7 is formed in the inner wall 3 between the two negative molds 4 and 5. The separation gap 8 defines two negative molds 4, 5, in other words defined by two spaced cutting edges 9 and 10. In this case, the cutting edges 9 and 10 define a gap width 11 of the separation gap 8.

  According to the invention, the cutting edges 9, 10 are arranged to be exposed on the inner wall 3. That is, the separation gap 8 is open and the cutting edges 9, 10 separate the inner wall 3 of the forming tool 2.

  A blank 12 that normally has a hollow cross section can be inserted into the forming tool 2.

  Furthermore, the molding and separating device 1 according to the invention is a feeding device in which a suitable pressure medium, preferably a liquid, in particular hydraulic oil, can be supplied into the material 12 and can operate at a suitable height of pressure. (Not shown in this figure). In addition, a corresponding control system (also not shown) is constantly provided to control the sequence of molding and separating operations in order to operate and control the feeder.

  The molding method and separation method according to the present invention or the molding and separation device 1 according to the present invention is as follows.

  First, the material 12 is inserted into the molding tool 2. Next, a feeding device is connected to the material 12. Thereafter, the internal high pressure can be formed in the material 12 after the molding tool 2 is closed.

According to FIG. 2, the material 12 is unfolded in this process, and the wall thickness 13 of the material 12 naturally decreases during this process. In this case, FIG. 2 shows the point or state of the forming and separating operations in which the material 12 is spread so that the outer contour 14 of the material 12 is in full surface contact with the inner contour of the negative dies 4,5. Yes. Full contact between the inner contour of the outer contour 14 and negative 4,5 material 12 is reliably achieved by the calibration pressure P _K. Therefore, the workpieces 6 and 7 are molded with the negative molds 4 and 5 at the calibration pressure P _K. However, in the state according to FIG. 2, the molded workpieces 6, 7 are still integral with each other or connected to each other via a section 15 arranged between them.

It may be convenient to constantly increase the internal high pressure to the calibration pressure P _K while applying pressure to the blank 12. It is important that the calibration pressure P _K is generated towards the end of the molding operation.

In a preferred embodiment of the invention, at the calibration pressure P _K , the separation gap 14 is pushed into the gap 8 according to FIG. 3 and is therefore cut and separated by the cutting edges 9, 10. 8 is adjusted to the calibration pressure P _K. The section 15 is shaped so as to be totally closed, complementary to the separation gap 8. At the calibration pressure P _K , the section 15 arranged between the workpieces 6, 7 is cut out and at the same time the separation of the two workpieces 6, 7 occurs. The workpieces 6 and 7 are then present in the forming tool 2 as separate components that are finished. In this embodiment of the method according to the invention, the combined forming and separating operations are performed in order to produce at least two workpieces 6 and 7 simultaneously. In particular, it is not necessary to increase the pressure in order to separate the processed products 6 and 7. As a result, firstly, it is easier to perform the forming / separating method, and secondly, the structure of the forming / separating device 1 is simpler, so that the workpiece can be manufactured more cost-effectively.

In the design of the molding tool 2, first the calibration pressure P _K required to make full contact between the outer side 14 of the blank 12 and the negative dies 4, 5 is determined. When this calibration pressure P _K is established, the wall thickness 13 remaining in the hollow section after molding is determined. Next, the shear force required to separate the section 15 from the workpieces 6 and 7 at the cutting edges 9 and 10 can be calculated from the remaining wall thickness. Next, using a shearing force, based on a predetermined outer periphery of the calibration pressure P _K and processed products 6 and 7 of the area of the separation gap 8 can be calculated gap width 11 necessary calibration pressure P _K is cut out segment 15. Once the gap width 11 of the separation gap 8 has been established, if each of the negative molds 4, 5 has moved to each of the cutting edges 9, 10, in this way both sides of the separation gap 8 of the forming tool 2. The positions of negative molds 4 and 5 are obtained.

  In order for the cutting operation to be performed as uniformly as possible, it may be necessary to change the separation gap 8 over the outer periphery.

In other embodiments, although not preferred, the separation gap 8 is set so that the calibration pressure P _K is insufficient to push the section 15 into the separation gap 8 or is insufficient to cut out the section 15. There is also the possibility of sizing. In this embodiment, then in the separation operation, the internal high pressure is accordingly raised above the calibration pressure P _K.

It is a schematic sectional drawing of the shaping | molding tool of the area | region of the separation gap in each state of a manufacturing process. It is a schematic sectional drawing of the shaping | molding tool of the area | region of the separation gap in each state of a manufacturing process. It is a schematic sectional drawing of the shaping | molding tool of the area | region of the separation gap in each state of a manufacturing process.

Claims (4)

A method for simultaneously producing at least two workpieces (6, 7) separated from each other by internal high pressure molding or hydroforming,
A forming tool in which the blank (12) has at least two negative molds (4, 5) and at least one separation gap (8) for each of the workpieces (6, 7) on the inner wall (3) 2), wherein the at least one separation gap is arranged between each two negative molds (4, 5), extends over the entire circumferential direction of the workpiece (6, 7) and is spaced apart Defined by two cutting edges (9, 10);
In a method in which the material (12) is acted on by an internal high pressure for molding to contact the inner wall (3) in the area of the negative mold (4, 5);
The cutting edges (9, 10) are exposed during the molding;
The raw material (12) penetrates into the gap during the molding in the region of the at least one gap (8), and the cutting edges (9, 10) have two respective workpieces (6, 7); )). The shaping is at least carried out towards the end at the calibration pressure (P _K ) chosen so that the blank (12) is in full contact with the inner wall (3) of the negative mold (4, 5). ,
The gap width (11) of the separation gap (8) is dimensioned so that the workpieces (6, 7) are separated at the calibration pressure (P _K ). The method described. An apparatus for simultaneously producing at least two workpieces (6, 7) separated from each other by internal high-pressure molding or hydroforming,
The material (12) can be inserted and has at least two negative molds (4, 5) and at least one separation gap (8) for each of the workpieces (6, 7) in the inner wall (3) A molding tool (2), wherein the at least one separation gap is arranged between each two negative molds (4, 5) and extends over the entire circumferential direction of the workpiece (6, 7). Having a forming tool (2) defined by two spaced apart cutting edges (9, 10);
-For feeding a pressure medium into the material inserted into the forming tool (2) such that the material (12) contacts the inner wall (3) in the area of the negative mold (4, 5); And an apparatus having a feeding device for applying internal high pressure to the inserted material (12),
-The cutting edges (9, 10) are arranged to be exposed at the inner wall (3) at least during molding;
In the region of the at least one gap (8), the material penetrates into the gap and the cutting edge (9, 10) is a section (15) between each two workpieces (6, 7); The device characterized in that the feeding device applies the internal high pressure to the material (12) so as to cut out the material. The molding of the blank (12) is finished at a calibration pressure (P _K ) selected so that the blank (12) is in full contact with the inner wall (3) of the negative mold (4, 5). The control system designed to actuate the feeder device at least as is done towards
The gap width (11) of the separation gap (8) is dimensioned so that the workpieces (6, 7) are separated at the calibration pressure (P _K ). The device described.

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