JP2006528075A - Method for producing a hollow cross-section element with sealed periphery - Google Patents

Abstract

  The present invention relates to a method for producing a hollow cross-section element with a sealed periphery by internal high-pressure molding. According to said method, the longitudinal hollow semi-finished product (5) is inserted into the internal high-pressure molding tool (1) and completely inserted into the molding tool (1) during the closing process of the molding tool (1). The semi-finished product (5) to be compressed is compressed in the region between its two ends (9, 10), after which the compressed semi-finished product (5) is subjected to a final shape of the hollow cross-sectional element by internal high pressure by the fluid To be expanded. The object of the present invention is to enable reliable production of hollow cross-section elements even when a large deformation of the semi-finished product (5) of the hollow cross-section elements occurs while the forming tool (1) is closed. It is. For this reason, the end parts (9, 10) of the semi-finished product (5) are cut out before the compression step to form obliquely cut front faces (12, 13), respectively, and the front faces (12, 12) of the end parts. 13) has an essentially flat shape and deforms the ends (9, 10) by a compression process so that it takes a position as perpendicular as possible to the longitudinal extension of the semi-finished product (5). For this purpose, the cutout contour and the inclination angle (α) of the end portions (9, 10) are selected.

Description

  The invention relates to a method according to the preamble of claim 1 for producing a hollow cross-section element with a sealed periphery.

  A general type of method is disclosed in US Pat. In this case, a semi-finished product with a hollow section element of uniform cross-section is inserted into an internal high-pressure molding tool, the tool cavity of which is reduced compared to the semi-finished product in the area between the ends of the tool It has a cross section. As a result, the inserted semi-finished hollow section element is compressed in this region during the closing operation of the forming tool. However, the end of the semi-finished product which extends linearly at the start of the manufacturing process and the front face of the semi-finished product is arranged at right angles to the longitudinal extension of the semi-finished product, Will be inclined or deformed. Due to the contour of the end being changed by compression and because of the inclination of the front surface, the axial plunger, which is provided with a conical sealing area and subsequently docks with the end of the semi-finished product, against the subsequent internal high pressure, Semi-finished products may be sealed very poorly. As a result, the subsequent operation to expand the semi-finished product by the internal high pressure due to the fluid is not completely ensured and therefore the hollow cross-section element cannot be produced as desired.

International Publication No. 98/43758 A1 Pamphlet

  The object of the present invention is that a general kind of method, which is intended to enable reliable production of hollow cross-section elements even during large compression deformation of the hollow cross-section element semi-finished product occurring during closing of the forming tool. Is to develop.

  This object is achieved according to the invention by the features of claim 1.

  The invention is based on the recognition that the end of the semi-finished product can be appropriately sized and cut to compensate for deformations that occur during compression of the semi-finished product. By cutting off the end of the semi-finished product according to the present invention, after compression and when the forming tool is completely closed, the front face of the end is flat and as perpendicular to the longitudinal extension of the semi-finished product as possible. The effect of being oriented is achieved. As a result of the positioning of the ends of the semi-finished products, the axial plunger can be docked with the ends of these semi-finished products as if the semi-finished products had not been cut and had not been previously compressed. Thus, the axial plunger can sufficiently seal both ends of the semi-finished product against the internal high pressure that is still taking place, thus allowing for reliable production of the hollow cross-section element. Furthermore, collisions due to chip removal between the axial plunger and, in addition, the semi-finished product provided with a tilted front face are avoided by the present invention, where the chips and debris produced in this process are After removing the finished hollow cross-section element, it must be removed in a complex manner during the next processing operation. Since this removal is usually associated with the cutting of the seal section at the end of the semi-finished product, the present invention allows such cutting operations to be omitted, thereby saving labor and making disposal difficult. It is possible to reduce scraps of new materials. The extra length that would have been lost in the semi-finished product no longer needs to be considered in advance, and as a result, the friction between the semi-finished product and the molding tool that must be overcome while continuing to expand the semi-finished product due to internal high pressure is This is significantly reduced because the length of the semi-finished product is reduced.

  In a preferred embodiment of the invention as claimed in claim 2, the front face of the end is cut obliquely with respect to a central axis which lies in the compression direction and runs transverse to the longitudinal axis of the semi-finished product, The end of the semi-finished product is cut off. This cut shape allows the deformation of the semi-finished product caused by compression based on the compression direction to result in a tilt of the cross section of the tube end with respect to the axis, and hence the tilt of the front surface, so that the tube end is Given by the additional recognition that it is cut diagonally in the opposite direction within the range. While the cross section is inclined as described above, the top peripheral region of the tube end protrudes in the axial direction from the bottom peripheral region.

  In a further preferred development of the invention as claimed in claim 3, the ends of the semi-finished products are cut out so that their front faces remain arranged parallel to one another. In the case where the end areas of the semi-finished hollow section elements are offset perpendicular to each other after compression has been performed, the bottom peripheral area is the end because the front face of one uncut end is inclined upwards. Since the front surface of the other end portion that protrudes in the axial direction from the top peripheral region of the portion is inclined downward, the top peripheral region of the end portion protrudes in the axial direction more than the bottom peripheral region. Thus, before the compression operation, both ends of the semi-finished product can be cut off at the same angle in opposite directions. The resulting cutting uniformity makes the work during cutting easier at the same time. Furthermore, the same applies to the lateral offset of the end after compression has taken place.

  A particularly preferred embodiment of the invention as defined in claim 4 constitutes a specific definition of the inclination angle of the cut which is in the range of 6 ° to 10 °, preferably 8 °. In this regard, practical and theoretical studies indicate that the front slope caused by compressive deformation is substantially always within this angular range, so that during cutting, an equal slope angle of the front face of the end is used. It became clear that it must be installed in the opposite direction.

  According to a further preferred embodiment of the invention as claimed in claim 5, the end deformation actually caused by the subsequent compression operation is confirmed by computer simulation, in particular finite element simulation, before cutting off the end, In order to compensate for the deformation, the optimum cutting contour and the optimum inclination angle of the cutting to be performed are accurately calculated by computer simulation. In this way, it is relatively easy to individually determine the tilt angle and the cutting contour suitable for each component and for all kinds of compression without using a great deal of tedious empirical research.

  According to a further preferred embodiment of the present invention as set forth in claim 6, the end cut-out is performed two-dimensionally. In this case, the exact contour of the space at the end of the semi-finished product is not recognized, but such cutting can be done particularly economically and quickly with respect to the method.

  In a particularly preferred embodiment of the invention as set forth in claim 7, the end cut-out is effected by a three-dimensional contour cut-out. This three-dimensional contour cutting can be done, for example, by a cutting laser and provides the best possible connection area for the axially docking plunger, so that an optimum seal is achieved with the plunger. The

  The present invention will be described in more detail with reference to the illustrated exemplary embodiments.

  FIG. 1 shows an internal high-pressure molding tool 1 consisting of a top 2 and a bottom 3. The tool mold cavity 4 which defines the forming space of the semi-finished product 5 of the hollow section element to be molded, which is molded by both tool parts 2 and 3 and is inserted into the tool 1, has one end 6 at the other end It is designed to be arranged with a vertical offset with respect to the end portion 7. In the closed molding tool 1 according to FIG. 2, these two ends 6 and 7 of the mold cavity have approximately the same diameter as the semi-finished product 5 of the inserted hollow section element. The mold cavity 4 is remarkably narrow in cross section in the central region 8 that connects the two ends 6 and 7 together.

  The semi-finished product 5 of the hollow cross-section element then has at its two ends 9 and 10 respective front faces 12 or 13 which are inclined in the direction of the longitudinal axis 11 of the semi-product 5 of the hollow cross-section element. The top peripheral region of the front surface 12 protrudes in the axial direction from the bottom peripheral region 15, whereas the bottom peripheral region of the front surface 13 protrudes in the axial direction from the top peripheral region 17. The semi-finished product 5 of the hollow cross-section element in which the front faces 12 and 13 of the end parts 9 and 10 of the semi-finished product 5 of the hollow cross-section element are arranged parallel to each other is arranged completely inside the mold cavity 4 of the molding tool 1. . The inclination angle α of the front surface 12 or 13 is 8 ° with respect to the central vertical axis 18, respectively.

  In order to produce a hollow cross-section element, the ends 9 and 10 of the semi-finished product 5 are first cut so as to obtain diagonally cut front faces 12 and 13, in this case the optimum deformation caused by the compression action In order to obtain a tight seal of the axial plunger that is docked after internal high-pressure molding, thus it is possible to cut the front faces 12 and 13 obliquely relative to the axis located in the compression direction . In the exemplary embodiment, the semi-finished ends 9 and 10 are cut so that their front faces 12 and 13 remain parallel to each other. In order to allow the desired cutout, the deformation of the ends 9 and 10 caused by the subsequent compression operation is confirmed by finite element computer simulation prior to the cutout operation, and then the appropriate cutout profile and the appropriate tilt angle α. Is calculated by this computer simulation. The semi-finished product 5 of the hollow cross-section element thus cut off is then inserted into the mold cavity 4 of the molding tool 1 and then the molding tool 1 is closed. Since the central region 8 of the mold cavity 4 is narrow, the hollow section element semi-finished product 5 is compressed by the top 2 and the bottom 3 moving towards each other during the closing operation of the molding tool 1. The central compression 19 showing the closed state of the forming tool 1 visible in FIG. 2 is hollow so that the front faces 12 and 13 of the semi-finished product 5 are arranged at right angles to the longitudinal extension of the semi-finished product 5. Acting on the ends 9 and 10 of the semi-finished product 5 of the sectional element. The axial plunger is then moved to the ends 9 and 10 of the semi-finished product 5 of the hollow cross-section element to seal the hollow cross-section element in the conical sealing area. Here, pressure fluid is introduced into the semi-finished product 5 of the hollow cross-section element via the axial plunger and is placed under high pressure. Due to the presence of internal high pressure, the hollow element cross-section semi-finished product 5 is expanded and fully abuts the mold cavity 4 of the molding tool 1. Here, the pressure fluid is allowed to escape from the now finished hollow cross-section element and flow out of it, after which the axial plunger is retracted from the forming tool 1. Finally, the molding tool 1 is opened and the hollow section element is removed from the mold cavity 4.

  In other respects, it is emphasized here that the semi-finished material can be compressed axially by an axial plunger during internal high pressure molding. For this reason, the present invention makes it possible to introduce a uniform force by the axial plunger to the molding region to be expanded in the internal high-pressure molding process by straightening the front surfaces 12 and 13. Thus, the introduction of this uniform force has the great advantage of making a significant contribution to process reliability due to the fact that undesirable wrinkle formation and thickness deviations are consequently avoided.

FIG. 2 is a transverse half section view of a semi-finished product of a hollow section element present in an opened molding tool and cut off on both sides according to the invention. FIG. 2 is a transverse half-sectional view of a semi-finished product of the hollow section element of FIG. 1 after a compression operation has been performed with a closed internal high-pressure forming tool.

Claims (7)

A method for producing a hollow cross-section element by sealing the periphery by means of internal high-pressure molding, in which a hollow elongated semi-finished product is inserted into the internal high-pressure molding tool and is completely placed inside the molding tool after insertion The semi-finished product is compressed in the region between the ends of the semi-finished product during the closing operation of the molding tool, after which the compressed semi-finished product is subjected to final pressure of the hollow cross-section element by internal high pressure due to fluid In a method that expands into a shape,
The end parts (9, 10) of the semi-finished product (5) are cut out before the compression operation to form respective front faces (12, 13) cut off obliquely, and the front face (12 , 13) have an essentially flat shape, and the compression operation causes the ends (9, 10) to be as perpendicular as possible to the longitudinal extension of the semi-finished product (5). ), The cutting contour and the inclination angle (α) of the ends (9, 10) are selected.   With respect to the central axis (18), the front faces (12, 13) of the ends (9, 10) are located in the compression direction and run transverse to the longitudinal axis (11) of the semi-finished product (5) The method according to claim 1, wherein the cutting is performed such that the cutting is performed obliquely.   3. The end of the semi-finished product is cut off so that the front faces (12, 13) of the ends (9, 10) remain arranged parallel to each other. The method described.   4. The method according to any one of claims 1 to 3, characterized in that the tilt angle ([alpha]) is in the range of 6 [deg.] To 10 [deg.], Preferably 8 [deg.].   The deformation of the end caused by the subsequent compression operation is confirmed by computer simulation before cutting out the end (9, 10), and then the cut contour and slope of the cut to be made to compensate for the deformation The method according to claim 1, wherein the angle (α) is calculated by the computer simulation.   6. Method according to any one of the preceding claims, characterized in that the cutting of the ends (9, 10) is performed two-dimensionally.   Method according to any one of the preceding claims, characterized in that the cutting of the ends (9, 10) is performed by cutting a three-dimensional contour.

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