Sealing die, device and method for internal high-pressure forming

Abstract

The present invention relates to a device for internal high-pressure forming of hollow chamber profiles and a sealing punch (1) for such a device, wherein the sealing punch (1) comprises at least two punch heads (3) arranged on a carrier plate (2), wherein the at least two punch heads (3) are set back inwards with respect to an outer edge (4) of the carrier plate (2) to form a sealing geometry (5), and the at least two punch heads (3) taper towards an end face (6) of the punch heads (3) facing away from the carrier plate (2). Furthermore, the sealing punch (1) has a high-pressure bore (9), wherein the high-pressure bore (9) comprises at least one branch (10), wherein the high-pressure bore (9) comprises outlets (11) in at least two of the punch heads (3), characterized in that a cross-sectional area of ​​a respective branch (10) of the high-pressure bore (9) corresponds to the size of an end face (6) of the respective punch head (3).from which an outlet (11) of the branch (10) emerges, and / or is adapted to the size of a chamber of a hollow chamber profile (50) to be formed using the sealing plunger (1), which is to be filled via this outlet. Furthermore, the invention relates to a method for internal high-pressure forming of a hollow chamber profile with a circumferential main contour, wherein a sealing punch (1) described above is pressed axially in the profile extension direction in front of a respective end of the hollow chamber profile.

Description

[0001] The invention relates to a sealing punch for a device for internal high-pressure forming of hollow chamber profiles, wherein the sealing punch comprises at least two punch heads arranged on a carrier plate, wherein the at least two punch heads are set back inwards with respect to an outer edge of the carrier plate to form a sealing geometry, and wherein the at least two punch heads taper towards an end face of the punch heads facing away from the carrier plate.

[0002] Furthermore, the invention relates to a device for internal high-pressure forming with a first sealing punch and a second sealing punch.

[0003] Furthermore, the invention relates to a method for internal high-pressure forming of a hollow chamber profile having a circumferential main contour, with a device for internal high-pressure forming, wherein a sealing punch is pressed axially in front of the profile in the profile extension direction.

[0004] In the prior art, a generic device for internal high-pressure forming and a generic method for internal high-pressure forming of a hollow chamber profile with a circumferential main contour are known from prior art EP 1 426 123 B1, wherein the sealing punch seals the profile only at the main contour.

[0005] Furthermore, EP 1 388 381 B1 describes a device for the internal high-pressure forming of hollow bodies, wherein the sealing dies of the device are designed as steel dies with a circumferential sealing geometry and have material accumulations at the groove beginnings for improved sealing and wear resistance. This is intended to ensure reliable sealing and forming of the hollow bodies under high internal pressure without the need for frequent die changes. Another method for internal high-pressure forming using a sealing die is known from CN 114425579 A.

[0006] Furthermore, EP 1 022 073 B1 discloses different designs for nozzle-shaped sealing dies for internal high-pressure forming, as well as a device and a method for internal high-pressure forming. The nozzles are used to generate the internal pressure necessary to form the material into the desired shape during the hydrostatic forming of pipes or profiles. The sealing dies are each designed to be adapted to different profiles and pipes for a reliable seal.

[0007] Furthermore, DE 10 2004 058 362 B3 describes a method and a device for manufacturing a multi-chamber hollow profile. The device comprises an axial piston with a sealing contour and outlet openings. The outlet openings form the closures of pressure fluid channels, which are fluidically connected to each other by a transverse bore. The transverse bore has a connection to a fluid supply on the outside of the axial piston.

[0008] Furthermore, a method for internal high-pressure forming of a double-chamber hollow profile is known from DE 199 09 929 A1. The device used for forming comprises a plate with bores to which elastomers projecting into the chambers of the profile are connected, and a forming fluid can be introduced through the bores.

[0009] To process internal high-pressure forming components, particularly pipes, single-chamber or multi-chamber profiles, using an internal high-pressure forming process, these components must be filled with a medium, usually a liquid, such as water, oil, an emulsion, or a gas. This allows internal pressure to build up, enabling the components to be formed. To prevent the medium from escaping the component and to maintain the internal pressure, the ends of the component are sealed by a sealing die, typically made of steel. By inserting the sealing die into a component end, the end is deformed in such a way that it is sealed, preventing the internal high-pressure medium from escaping between the sealing die and the component end.

[0010] A disadvantage is the comparatively long filling time required to fill the component to be formed with the internal high-pressure forming medium. Furthermore, the air contained within the component must be able to escape during this process. This takes a particularly long time with large-volume components and multi-chamber profiles. If a significant amount of air remains in the component, the pressure build-up during the internal high-pressure forming process takes considerably longer, as much more volume and energy are required to compress the remaining air than would be the case with a liquid internal high-pressure forming medium.

[0011] When forming multi-chamber profiles, an additional challenge arises: all chambers must be filled with the internal high-pressure medium, and the air must escape from all chambers. Small chambers on the component are particularly difficult to fill.

[0012] Against this background, an object of the present invention is to improve internal high-pressure forming, and in particular to provide an improved sealing die for internal high-pressure forming, an improved device for internal high-pressure forming, and an improved method for internal high-pressure forming. In particular, the time required for internal high-pressure forming of a component is to be reduced.

[0013] To solve this problem, a sealing die, a device for internal high-pressure forming, and a method for internal high-pressure forming are proposed according to the independent claims. Further advantageous embodiments of the invention are described in the dependent claims and the description and are illustrated in the figures.

[0014] The proposed solution provides a sealing die for a device for the internal high-pressure forming of hollow chamber profiles, wherein the sealing die comprises at least two die heads arranged on a carrier plate, wherein the at least two die heads are set back inwards with respect to an outer edge of the carrier plate to form a sealing geometry, and wherein the at least two die heads taper towards an end face of the die heads facing away from the carrier plate. The sealing die also comprises a high-pressure bore, which is designed in particular for connecting a pressure medium source through which the internal high-pressure forming medium can be supplied. The high-pressure bore comprises at least one branch, wherein the high-pressure bore advantageously includes outlets in at least two of the die heads, in particular such that there is one outlet per die head.In particular, the high-pressure bore is provided to have two branches, the branched high-pressure bore being advantageously Y-shaped, in particular by a straight bore and two oblique bores, i.e., two branches, or V-shaped, i.e., by two oblique bores. However, the high-pressure bore can also be designed to be straight with only one branch. Advantageously, the branching allows for the direct filling of several chambers of a multi-chamber hollow profile and thus accelerates an internal high-pressure forming process, especially because the filling time for multi-chamber profiles can be reduced. An advantageous embodiment provides a sealing ram with exactly two ram heads for a two-chamber hollow profile, each ram head having a feed bore branching off from the high-pressure bore, i.e., one for each chamber.This has the advantage that each chamber can be filled directly, thus significantly reducing the filling time.

[0015] The sealing geometry of the sealing punch includes, in particular, a sealing edge. Advantageously, the sealing edge is designed and adapted to the component to be formed such that, when the sealing punch is pressed into the component, the sealing edge deforms and compresses material on the inside of the component's main contour. This advantageously improves the sealing effect. Furthermore, the sealing geometry of the sealing punch advantageously includes a thrusting edge with which material compressed by the sealing edge is advanced further for a further improved seal and placed between the punch head and the inside of the component's main contour. Alternatively or additionally, the thrusting edge can also be used, in particular, for sealing by surface pressure.

[0016] The sealing plunger is advantageously made of steel. In particular, at least one of the at least two plunger heads has a through-opening, in particular a through-bore, which extends through the entire plunger head and the carrier plate, wherein the sealing plunger can be arranged on a lock cylinder by means of a fastening means, in particular a screw bolt, inserted into the through-opening.

[0017] According to a further advantageous embodiment of the sealing piston, the high-pressure bore with its at least one branch is designed such that the design of the high-pressure bore and the at least one branch determines a predetermined outflow characteristic at the outlets of the high-pressure bore. Advantageously, the design of the high-pressure bore and, in particular, its branches, thus defines a volume flow rate exiting an outlet, especially with regard to the outflow quantity at the outlet. In the case of a symmetrically designed sealing piston with two outlets, a ratio of 1:1 for the outflow quantity at the outlets can thus be established.In the case of an asymmetrically designed sealing piston, ratios deviating from a 1:1 ratio can be defined, which are adapted in particular to the volume of a chamber to be filled within a hollow chamber profile to be formed by the sealing piston. These ratios can be defined in particular by the targeted introduction of flow obstructions in at least one branch, especially by creating a branch through two bores offset from each other at a 90° angle.

[0018] According to the invention, the cross-sectional area of ​​each branch of the high-pressure bore is adapted to the size of an end face of the respective punch head from which an outlet of the branch emerges, and / or to the size of a chamber to be filled via this outlet in a hollow chamber profile formed using the sealing punch. It should be taken into account that the size of an end face of a punch head is in many cases already proportional to the size of a chamber to be filled in a hollow chamber profile formed using the sealing punch. In particular, it is provided that the cross-sectional area of ​​each branch is proportional to the size of the end face of the respective punch head.Advantageously, chambers of different sizes in a multi-chamber hollow profile can be filled particularly evenly, which further accelerates the filling time and thus the internal high-pressure forming process.

[0019] Advantageously, at least one side surface of at least one of the punch heads, which borders the sealing geometry, in particular a sealing edge of the sealing geometry, has at least one venting recess, in particular at least one venting groove. Advantageously, the venting recess ensures that the time required for internal high-pressure forming of a component can be reduced because the venting of the component to be formed can be improved with the proposed sealing punch. This is because, when the sealing punch is positioned close to the end of the profile and the component does not yet seal completely in this position, the component to be formed can advantageously be filled with an internal high-pressure forming medium, with the at least one venting recess advantageously ensuring that the air contained in the component can escape from the component via the at least one venting recess.

[0020] In particular, a sealing die for a device for internal high-pressure forming of hollow chamber profiles is also proposed, wherein the sealing die comprises at least one die head arranged on a carrier plate, and in particular at least two die heads, wherein the at least one die head is set back inwards with respect to an outer edge of the carrier plate to form a sealing geometry, and wherein the at least one die head tapers towards an end face of the die head facing away from the carrier plate. In this embodiment, at least one side surface of the at least one die head, which adjoins the sealing geometry, in particular a sealing edge of the sealing geometry, has at least one venting recess, in particular at least one venting groove.

[0021] Advantageously, with regard to an insertion position of the sealing punch, particularly with regard to an insertion position of the sealing punch into a hollow chamber profile to be formed, at least one upwardly facing side surface of the at least one punch head has at least one venting recess. Preferably, only at least one upwardly facing side surface of the at least one punch head has at least one venting recess.When the component to be formed is filled with an internal high-pressure forming medium, the venting recess on at least one upper side surface of the at least one punch head advantageously ensures that any air remaining in the component to be formed can easily escape via the venting recess on this at least one upper side surface, while in the lower part of the sealing punch, the component to be formed is advantageously already relatively well sealed with respect to an insertion position of the sealing punch, and thus, advantageously, leakage of the internal high-pressure forming medium in the lower area of ​​the sealing punch can be largely prevented.By arranging the at least one venting recess in at least one side surface of the at least one punch head that faces upwards with respect to the insertion position of the sealing punch, the filling time with the internal high-pressure forming medium is advantageously reduced considerably, and thus the entire internal high-pressure forming process is advantageously accelerated. The solution with the at least one venting recess is particularly suitable for pipes, single-chamber and / or multi-chamber profiles.

[0022] A further advantageous embodiment provides that the at least one venting recess extends essentially in the insertion direction in which the sealing plunger is inserted into a hollow chamber profile. Advantageously, this further improves venting when filling a component to be formed with an internal high-pressure forming medium.

[0023] According to a further advantageous embodiment, the at least one venting recess in the side surface of the punch head extends over a length that corresponds to at least 10% and at most 98%, and in particular at least 50% and at most 98%, of the length of the side surface of the respective punch head relative to the insertion direction of the sealing punch. Advantageously, this allows for good venting when filling a component to be formed with an internal high-pressure forming medium. Furthermore, it advantageously maintains a good sealing effect of the sealing punch, particularly when the sealing punch is fully inserted into a component to be formed.

[0024] Advantageously, the at least one venting recess in the side surface of the at least one punch head extends over a width that corresponds to at least 1% and at most 40% of the width of the side surface of the respective punch head measured perpendicular to the insertion direction of the sealing punch. Particularly good venting results can be achieved with such a width.

[0025] A further advantageous embodiment provides that the at least one venting recess has a rounded wall. Advantageously, a mathematical curve describing a cross-section of the at least one venting recess has a continuous profile. Advantageously, turbulence within the venting recess caused by escaping air during venting is largely avoided, thereby further accelerating the venting process. In particular, it is provided that the at least one venting recess is semi-tubular in shape. A rounding of the venting recess, especially at the transitions to the side surface into which the venting recess is integrated, is advantageous because, among other things, this prevents the formation of chips during sealing.

[0026] According to a further advantageous embodiment of the invention, the sealing die comprises at least two die heads, each separated from the other by a groove. Advantageously, the groove has recesses. In particular, the groove has a base depth, with the recesses being deeper than the base depth. This sealing die is advantageously designed for forming multi-chamber profiles, wherein an inner wall of the multi-chamber profile, separating two chambers, projects into a groove, and the recesses facilitate the passage of an internal high-pressure medium and / or residual air remaining in the multi-chamber profile from one chamber to another via the recesses, thus further accelerating the filling and venting of the multi-chamber profile.

[0027] In particular, a sealing die for a device for the internal high-pressure forming of hollow chamber profiles is also proposed, wherein the sealing die comprises at least two die heads arranged on a carrier plate, wherein the at least two die heads are recessed inwards with respect to an outer edge of the carrier plate to form a sealing geometry, and wherein the at least two die heads taper towards an end face of the die heads facing away from the carrier plate. The at least two die heads are each separated from one another by a groove, wherein the groove has recesses. In particular, the groove has a base depth, wherein the recesses are deeper than the base depth.This sealing die is advantageously designed for forming multi-chamber profiles, wherein an inner wall of the multi-chamber profile separating two chambers projects into a groove and the recesses thereby improve the ability for an internal high-pressure medium and / or residual air remaining in the multi-chamber profile to pass from one chamber to another via the recesses, thus further accelerating the filling and venting of the multi-chamber profile.

[0028] Advantageously, in the proposed sealing dies, the recesses extend into the side surfaces of the grooves. This further improves the transfer of an internal high-pressure medium and / or residual air from one chamber to another within a multi-chamber profile being formed, and advantageously accelerates the internal high-pressure forming process.

[0029] In particular, the recesses in a groove separating two punch heads ensure the flow of the internal high-pressure medium even during the further insertion of the sealing punch into the hollow chamber profile being formed, i.e., during the axial movement of the sealing punch to seal the component being formed, from chamber to chamber of the hollow chamber profile. Thus, advantageously, at least almost the same pressure is ensured in all profile chambers throughout the entire process, and a differential pressure, which would negatively affect the forming result, is avoided by the recesses while simultaneously optimizing the cycle time.

[0030] The device for internal high-pressure forming proposed to solve the aforementioned problem comprises a first sealing die and a second sealing die, wherein the first sealing die is designed as a sealing die according to the invention and / or the second sealing die is designed as a sealing die according to the invention. The first sealing die and / or the second sealing die can therefore advantageously have features of the embodiment described above, either individually or in combination. In particular, it can be provided that only one of the sealing dies comprises a high-pressure bore through which an internal high-pressure forming medium is introduced as a pressure medium into a component to be formed.

[0031] In particular, the device for internal high-pressure forming comprises an upper tool part and a lower tool part, wherein the tool parts define the final shape of the component to be formed. Furthermore, the device includes, in particular, two locking cylinders, especially hydraulically movable locking cylinders, on which the sealing punches are advantageously arranged. The device also includes, in particular, a pressure medium source, which advantageously supplies the internal high-pressure forming medium via the high-pressure bore of the sealing punch(es) at the pressure required for forming.

[0032] The proposed method for internal high-pressure forming of a hollow chamber profile with a circumferential main contour, which addresses the aforementioned problem, involves pressing a sealing punch in the profile's extension direction, i.e., in the axial direction, against each end of the hollow chamber profile. The sealing punch is designed according to the invention and, in particular, has the features described individually or in combination with the described embodiments. Furthermore, the internal high-pressure forming is carried out using a device for internal high-pressure forming designed according to the invention. The method can be used, in particular, to form tubes as well as single- and multi-chamber hollow profiles.

[0033] If at least one of the punch heads has a venting recess, it is advantageously provided that the sealing punch is moved into a venting position before it is finally pressed against each end of the hollow chamber profile. In this venting position, the sealing punch is not yet fully in front of, and in particular, the at least one punch head is not yet fully pressed into, the hollow chamber profile. In the venting position, the internal high-pressure forming medium is (further) introduced into the hollow chamber profile, especially via the high-pressure bore of the sealing punch. In the venting position, air displaced by the introduction of the internal high-pressure forming medium can advantageously escape via the at least one venting recess of the sealing punch, whereby the sealing punch advantageously already seals the hollow chamber profile, particularly in its lower part and on the sides.By providing the venting position, the internal high-pressure forming medium can advantageously be introduced more quickly and completely, thus accelerating the internal high-pressure forming process.

[0034] Advantageously, the sealing plunger is advanced into the hollow chamber profile with the plunger head, controlled by pressure and / or time, and the filling pressure generated by the internal high-pressure forming medium is increased. In a further position, where venting via the at least one venting recess is no longer possible, filling advantageously takes place with a first pressure stage. In a sealing position, where venting via the at least one venting recess is still no longer possible, and which corresponds in particular to a final position, the filled internal high-pressure forming medium is advantageously pressurized according to a second pressure stage, in particular with a maximum pressure intended for the forming process.

[0035] Further advantageous details, features and embodiments of the invention are explained in more detail in connection with the exemplary embodiments shown in the figures (Fig.: Figure). These show: Fig. 1 in a simplified lateral sectional view an embodiment of a device designed according to the invention for internal high-pressure forming; Fig. 2 in a perspective view an embodiment of a sealing piston designed according to the invention; Fig. 3 in a sectional view Along the section line AA the sealing piston according to Fig. 2; Fig. 4a in simplified side views at different times, an embodiment of a method designed according to the invention for Fig. 4D internal high-pressure forming; and Fig. 5 an enlarged section of the sealing piston 1 according to Fig. 3 with sealing geometry.

[0036] In the various figures, identical parts are generally marked with the same reference symbols and are therefore sometimes only explained in connection with one of the figures. The illustrations in the figures are simplified, particularly in the more detailed views, for the sake of clarity.

[0037] In Fig. Figure 1 shows an embodiment of a device 100 for internal high-pressure forming of a hollow chamber profile 50. The device 100 comprises an upper tool part 105 and a lower tool part 106, which firmly enclose the hollow chamber profile 50 to be formed for internal high-pressure forming and whose design determines the subsequent shape of the hollow chamber profile 50. The hollow chamber profile 50 to be formed is arranged in its longitudinal direction between the upper tool part 105 and the lower tool part 106, as shown in Figure 1. Fig. 1 shown as an example.

[0038] The device 100 also features two hydraulic locking cylinders on its sides, each with a sealing plunger 1 screwed firmly to its movable end. Depending on the design of the hollow chamber profile 50 to be formed, the sealing plungers 1 have at least two plunger heads arranged on a carrier plate. The plunger heads are recessed inwards relative to an outer edge of the carrier plate to form a sealing geometry. This sealing geometry ultimately presses the sealing plunger 1 against a circumferential main contour of the hollow chamber profile 50 to be formed in the respective insertion direction R. Furthermore, the plunger heads taper towards an end face facing away from the carrier plate, which simplifies the insertion of the plunger heads into the respective end of the hollow chamber profile 50 to be formed.Due to the conical design of the punch heads and a sealing edge of the sealing geometry, the wall thickness at the end 52 of the hollow chamber profile 50 is reduced by the respective punch head, thus sealing the hollow chamber profile 50 at its end 52. At least one side surface of the punch heads adjacent to the sealing geometry, in particular to the sealing edge, also has at least one vent recess 8, through which air contained in the hollow chamber profile 50 can escape when the hollow chamber profile 50 is filled with an internal high-pressure forming medium.

[0039] For filling the hollow chamber profile 50 with an internal high-pressure forming medium, the device 100 also includes a Fig. 1. A pressure medium source (not explicitly shown) is configured to supply the internal high-pressure forming medium via a high-pressure bore in the respective sealing punch 1 at the pressure required for forming the hollow chamber profile 50, thus bringing the hollow chamber profile 50 into the shape defined by the upper tool part 105 and the lower tool part 106. The high-pressure bore has an inlet opening on one side facing away from the hollow chamber profile 50 to be formed and an outlet opening in each punch head, and is therefore branched. The individual chambers of the hollow chamber profile 50 can thus be filled directly via the respective outlet in the respective punch head.

[0040] For the internal high-pressure forming of a hollow chamber profile 50 with the device 100, the hollow chamber profile 50 to be formed is first arranged between the lower tool part 106 and the upper tool part 106. Advantageously, even before the sealing punches 1 are inserted into the hollow chamber profile 50 to be formed, an internal high-pressure forming medium is introduced into the hollow chamber profile 50, which at this point is advantageously not done, or at least not exclusively, via the high-pressure bore of the sealing punch 1.Then, using the locking cylinders 108, which are also referred to as axial locking cylinders, the sealing punches 1 are inserted with the punch heads 3 leading into the respective end 52 of the hollow chamber profile 50, and pressed into the hollow chamber profile 50 to such an extent that in the area of ​​the respective sealing punch 1 outside the respective vent recess, a seal is already formed by the sealing punch 1 against the escape of an internal high-pressure forming medium introduced into the hollow chamber profile 50, but air can still escape from the hollow chamber profile 50 to be formed through at least one vent recess of the respective sealing punch 1.In particular, the sealing dies 1 are then inserted into the hollow chamber profile 50 up to the stop formed by the respective sealing geometry, and brought into the shape specified by the tool parts 105, 106 by increasing the pressure via the high-pressure bore with which the internal high-pressure forming medium in the hollow chamber profile 50 is acted upon.

[0041] A possible advantageous embodiment of a sealing die 1, which can be used with the device 100 for internal high-pressure forming, is described below with reference to Fig. 2 and Fig. 3 explained in more detail Fig. 3 a cut through the sealing piston 1 according to Fig. 2 along line AA. Fig. Figure 5 also shows an enlarged section of the illustration of the sealing end 5 of the sealing piston 1. Fig. 3.

[0042] The in Fig. 2 and Fig. The sealing die 1 shown in Figure 3 is a sealing die 1 for a device for internal high-pressure forming of hollow chamber profiles, wherein the in Fig. 2 and Fig. Figure 3 shows a sealing die 1 specifically designed for forming a symmetrical two-chamber hollow profile with a circumferential main contour. In this embodiment, the sealing die 1 is made of steel and has a carrier plate 2 with two die heads 3 arranged on it. These die heads 3 are symmetrically designed in this embodiment, the design and number of die heads 3 depending in particular on the component to be formed.

[0043] The punch heads 3 of the sealing punch 1 are recessed inwards with respect to an outer edge 4 of the carrier plate 2 to form a sealing geometry 5, wherein the sealing geometry 5 thus formed particularly constitutes a stop for a main contour surrounding the component to be formed. In this embodiment, the sealing geometry 5 comprises a sealing edge 5a and a follow-up edge 5b, as also in Fig. Figure 5 is shown enlarged, with the sealing geometry 5 depicted as a dashed line. The sealing punch 1 is adapted to a hollow chamber profile to be formed such that, when the punch heads 3 are pressed into the hollow chamber profile, the sealing edge 5a takes material from the inside of the outer contour of the hollow chamber profile and is pushed further by the follower edge 5b and placed between the respective punch head 3 and the inside of the main contour of the hollow chamber profile. To facilitate insertion and improve sealing, the respective punch head 3 of the sealing punch 3 tapers, as shown in Fig. 2 and Fig. 3 shown, towards one of the end faces 6 of the stamp head 3 facing away from the carrier plate 2.

[0044] The punch heads 3 of the sealing punch 1 are also separated from each other by a groove 14, wherein an intermediate wall separating the hollow chamber profile to be formed into its two chambers projects into the groove 14 when the sealing punch 1 is inserted into one end of the hollow chamber profile. The groove 14 has a basic depth GT, which, as shown in Fig. As can be seen in Figure 3, the groove 14 does not extend to the height of the sealing geometry 5 at its ends. In this embodiment, the groove 14 is deeper than the thrust edge 5b over most of its length, in particular over 95% of its length, and in particular several millimeters deeper. Since the sealing edge 5a must seal the hollow chamber profile to be formed all around, the groove 14 is less deep in the area of ​​the sealing edge 5a, which can correspond in particular to about 5% of the groove length. The groove 14 also has recesses 15 extending beyond the basic depth GT, which are deeper than the basic depth GT and also extend into the side surfaces 16 of the groove 14. Fluid exchange between the two chambers of the two-chamber hollow profile can thus take place via the groove 14 and these recesses 15, even when the sealing plunger 1 is completely inserted into one end of the hollow profile.

[0045] An upwardly facing side surface 71 of the side surfaces 7 of the respective punch head 3 of the sealing punch 1 also has, with respect to an insertion position PE of the sealing punch 1, a venting recess 8 designed as a venting groove with a rounded surface. Preferably, the edges of the venting recess 8 are rounded to prevent chips during insertion, which is not explicitly shown in the figures.The two venting recesses 8 of the sealing punch 1 extend essentially in an insertion direction R, into which the sealing punch 1 is inserted for intended use into a hollow chamber profile, wherein the venting recesses 8 extend essentially over a length which corresponds to approximately 90% of a length LS of a side surface 7 of the punch heads 3 related to the insertion direction R of the sealing punch 1, and a width which corresponds to approximately 10% of a width BS of the side surface 7 in the area of ​​the end face 6 of the punch head 3 related to a width BS of the side surface 7 in the area of ​​the end face 6 of the punch head 3.

[0046] Furthermore, the punch heads 3 of the sealing punch 1 each have a through-bore 30, via which the sealing punch 1 can be mounted on a locking cylinder 108 of a device 100 for internal high-pressure forming using appropriately designed screw bolts. The sealing punch 1 also has a high-pressure bore 9, via which a pressure medium source providing an internal high-pressure forming medium can be connected to the sealing punch 1 from the carrier plate side. The high-pressure bore 9 comprises a V-shaped high-pressure bore with two branches 10 and two outlets 11, with each of the punch heads 3 having one of the outlets 11. In this embodiment, the cross-sectional areas of the branches 10 are equal, so that an equal volume flow can exit through each of the outlets 11.Both chambers of a two-chamber hollow profile to be formed can be filled directly via the two outlets 11, advantageously requiring only one connection for the pressure medium source. Such a design of the sealing piston 1, in which the high-pressure bore 9 has two branches 10 and only one inlet but two or at least two outlets 11, is particularly advantageous even independently of the presence of the venting recesses 8, because it allows the filling of a hollow chamber profile to be formed, and thus the overall high-pressure forming process, to be carried out faster than with sealing pistons known to date.If, contrary to the embodiment shown here, the surfaces of the end faces 6 of the punch heads 3 were of different sizes, it would be advantageous if the branching in the punch head 3 with the smaller end face surface had a smaller cross-sectional area than the branching in the punch head 3 with the larger end face surface, so that ideally both chambers of a component to be formed are filled essentially simultaneously.

[0047] An advantageous embodiment for a method for internal high-pressure forming of a hollow chamber profile 50 with a circumferential main contour 54 in which a sealing die 1 designed according to the invention is used is described below with reference to Fig. 4a to Fig. 4d described. This shows Fig. 4a to Fig. 4d each greatly simplified only a sealing die 1 and the hollow chamber profile 50 to be formed. The sealing die 1 can, in particular, as shown in Fig. 2 to Fig. Figure 3 is shown. Of particular importance is that the sealing punch 1 has at least one venting recess 8, wherein, in this embodiment, the at least one venting recess 8 is provided in an upper side surface 71 of the side surfaces 7 of the at least one punch head 3. In particular, the method provides that two sealing punches 1 are used, each arranged at one end 52 of the hollow chamber profile 50 to be formed. For better clarity, in Fig. 4a to Fig. 4d, however, shows only one sealing plunger 1 with an end section of a hollow chamber profile 50. The explanation of the method refers only to this one sealing plunger 1, the method specifically providing that two sealing plungers 1 are arranged at the ends 52 of the hollow chamber profile 50 and are adjusted synchronously, in particular by means of corresponding locking cylinders, as described in Figure 4d. Fig. 1 explained.

[0048] Fig. 4a shows the sealing die 1 in an insertion position P0, in which the hollow chamber profile 50 to be formed is positioned between the upper tool part and the lower tool part (in Fig. 4a to Fig. (4d not shown) is inserted for a forming process. If the hollow chamber profile 50 is correctly inserted and the tool parts are closed, filling the hollow chamber profile 50 with the internal high-pressure forming medium can begin as early as the insertion position P0, which can be done via an additional supply line in the tool, at least supplementing the high-pressure bore. The sealing punch 1 is moved into a venting position PE, in particular after 1 s to 10 s (s: seconds), the time being determined primarily by the component and component geometry, especially using locking cylinders, as shown in Fig. Figure 1 illustrates this. The sealing plunger 1 is pressed axially in the profile extension direction in front of the end 52 of the hollow chamber profile 50, but only to the extent that the sealing edge 5a of the sealing geometry 5 of the sealing plunger 1 does not yet contact the main contour 54 of the hollow chamber profile 50, and the at least one vent recess 8 at the end of the vent recess 8 facing away from an end face 6 of the plunger heads 3 of the sealing plunger 1 is not closed by being inserted into the hollow chamber profile 50. When the plunger heads 3 of the sealing plunger 1 are inserted into the hollow chamber profile 50, the end 52 of the hollow chamber profile 50 is selectively deformed by the sealing edge 5a. In order to seal the end 52 of the hollow comb profile 50, in this embodiment the wall thickness of the outer contour 54 of the hollow comb profile 50 is reduced at the end 52 of the hollow comb profile 50 by the punch heads 3 and the sealing edge 5a.Alternatively or additionally, compression can also be carried out in an axial direction, in particular by the pushing edge 5b. Fig. 4b shows the sealing piston 1 in the venting position PE.

[0049] In the venting position PE, an internal high-pressure forming medium is introduced into the hollow chamber profile 50 via a high-pressure bore 9 of the sealing piston 1. To accelerate the filling of the chambers of the hollow chamber profile 50, the high-pressure bore 9 of the sealing piston 1 has a branch with several outlets 11. Compared to a single central outlet opening, this advantageously avoids the situation where only one chamber is initially filled, from which the internal high-pressure forming medium then has to flow into the other chambers, which would slow down the cycle time. The internal high-pressure forming medium introduced into the hollow chamber profile 50 displaces the air contained within the hollow chamber profile 50, which escapes through the at least one vent recess 8 of the sealing piston 1. Without the vent recesses 8, venting would take a very long time, especially with large-volume components.Furthermore, this would increase the likelihood of residual air remaining in the hollow chamber profile, which can negatively affect the cycle time, energy consumption, and forming result. When filling the hollow chamber profile 50 with the internal high-pressure forming medium, the pressure at which the internal high-pressure forming medium is introduced into the hollow chamber profile 50 can be monitored. With reference to... Fig. 4a to Fig. However, in the embodiment described in 4d, it is provided that the transitions from the insertion position P0 to the sealing position P2 are time-controlled.

[0050] After a predetermined time, which depends in particular on the component and component geometry and can be between 1 s and 10 s, the sealing piston 1 is moved from the venting position PE to a further position P1, in which filling with a first pressure stage takes place in which the pressure with which the internal high-pressure forming medium is acted upon can be further increased. Fig. Figure 4c shows the sealing plunger 1 in the first position P1. After a further predetermined time, which again depends in particular on the component and component geometry and can be between 1 s and 10 s, the sealing plunger 1 is moved further into a sealing position P2, in which the sealing plunger 1 completely seals the hollow chamber profile 50. When the sealing position P2 is reached, the hollow chamber profile 50 to be formed is filled via the high-pressure bore 9 until a minimum pressure, in particular a component-dependent minimum pressure, which can be between 10 bar and 100 bar, is reached. The actual internal high-pressure forming process then begins with a controlled pressure build-up and axial pushing using the closing cylinders 108. Fig. Figure 4d shows the sealing piston in position P2 (sealing position).

[0051] When a multi-chamber hollow profile is formed according to the described method, it is specifically provided that the punch heads 3 of the sealing punch 1 are each separated from one another by a groove, each groove having a basic depth adapted to the intermediate walls of the multi-chamber hollow profile 50. The grooves each have recesses that are significantly deeper than the basic depth. These recesses ensure the flow of the internal high-pressure forming medium between the chambers of the multi-chamber hollow profile, even during the movement of the sealing punch 1 from the filling position PE to the sealing position P2. Thus, a constant pressure can be maintained in all profile chambers of the multi-chamber hollow profile, and differential pressures between the chambers, which could negatively affect the forming result, can be avoided.

[0052] The embodiments shown in the figures and explained in connection with them serve to illustrate the invention and are not limiting to it. Reference symbol list 1 sealing stamp 2 Carrier plate 3 Stamp head 4 Outer edge of the carrier plate (2) 5 Sealing geometry 5a Sealing edge 5b Sliding edge 6 Front face of the stamp head (3) 7 Side surface of the stamp head (3) 71 upward-facing side surface of the stamp head (3) 8. Ventilation recess 9 High-pressure borehole 10 Branching of the high-pressure borehole (9) 11 Outlet of the branch (10) of the high-pressure borehole (9) 14 Nut 15 recesses of the groove (14) 16 Side surface of the groove (14) 30 through holes 50 Hollow chamber profile 52 End of the hollow chamber profile (50) 54 Main contour of the hollow chamber profile (50) 100 Device for internal high-pressure forming 105 upper tool part 106 lower tool part 108 locking cylinders AA section line R Direction of insertion LS Length of the side surface (7) of the stamp head (3) BS Width of the side surface (7) of the stamp head (3) GT Groove base depth (14) P0 insertion position PE vent position P1 further position P2 sealing position

Claims

[1] Sealing die (1) for a device (100) for internal high-pressure forming of hollow chamber profiles (50), wherein the sealing die (1) comprises at least two die heads (3) arranged on a carrier plate (2), wherein the at least two die heads (3) are set back inwards with respect to an outer edge (4) of the carrier plate (2) to form a sealing geometry (5), wherein the at least two die heads (3) taper towards an end face (6) of the die heads (3) facing away from the carrier plate (2), wherein the sealing die (1) has a high-pressure bore (9), wherein the high-pressure bore (9) comprises at least one branch (10), and wherein the high-pressure bore (9) comprises outlets (11) in at least two of the die heads (3), characterized by, that a cross-sectional area of ​​a respective branch (10) of the high-pressure bore (9) is adapted to a size of an end face (6) of the respective punch head (3) from which an outlet (11) of the branch (10) exits, and / or to a size of a chamber to be filled via this outlet of a hollow chamber profile (50) to be formed using the sealing punch (1). [2] Sealing die (1) according to claim 1, characterized by , that the high-pressure bore (9) is Y- or V-shaped. [3] Sealing die (1) according to claim 1 or claim 2, characterized by , that the high-pressure bore (9) with the at least one branch (10) is designed such that the design of the high-pressure bore (9) and the at least one branch (10) determines an outflow behavior at the outlets. [4] Sealing die (1) according to one of the preceding claims, characterized by, that at least one side surface (7) of at least one of the punch heads (3) which adjoins the sealing geometry (5) has at least one venting recess (8), in particular at least one venting groove. [5] Sealing die (1) according to one of the preceding claims, characterized by that the punch heads (3) are each separated from each other by a groove (14), the groove (14) having recesses (15). [6] Sealing die (1) according to claim 5, characterized by , that the groove (14) has a basic depth (GT), wherein the depressions (15) are deeper than the basic depth (GT). [7] Sealing die (1) according to claim 5 or claim 6, characterized by , that the recesses (15) extend into the side surfaces (16) of the groove (14). [8] Device (100) for internal high-pressure forming of a hollow chamber profile (50) with a first sealing punch (1) and a second sealing punch (1), characterized by, that the first sealing plunger (1) is designed according to one of the preceding claims and / or the second sealing plunger (1) is designed according to one of the preceding claims. [9] Method for internal high-pressure forming of a hollow chamber profile (50) with a circumferential main contour, wherein a sealing punch (1) is pressed axially in the profile extension direction in front of each end (52) of the hollow chamber profile (50), characterized by , that the sealing piston (1) is designed according to one of claims 1 to 7.

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