WO2005056211A1

WO2005056211A1 - Internal high-pressure shaping device

Info

Publication number: WO2005056211A1
Application number: PCT/EP2004/013015
Authority: WO
Inventors: Matthias Schroeder; Stefan Schwarz
Original assignee: Daimlerchrysler Ag
Priority date: 2003-12-13
Filing date: 2004-11-17
Publication date: 2005-06-23
Also published as: CA2550124A1; DE10358493B4; US20070277574A1; DE10358493A1

Abstract

The invention relates to a device (10) for the internal high-pressure shaping of a hollow profile (5), comprising a shaping tool and a sealing device for holding and sealing an end (12) of the hollow profile (5) projecting out of the cavity (16) of the shaping tool. To this end, the sealing device (11) has a section (6) of an axial die (4) protruding into the hollow profile (5) and has at least one clamping jaw (3). When the section (6) of the axial die (4) protrudes, the clamping jaw can be radially pressed from the outside against the hollow profile end (12) in such a manner that the clamping jaw (3) fixes the hollow profile end in the position thereof. In addition, an actuator (14) is provided that drives the clamping jaw (3) for displacing it only radially to the hollow profile axis. According to the invention, at least one annular tooth (2) is placed on a side of the clamping jaw (3) facing a hollow profile end (12).

Description

Device for hydroforming

The present invention relates to a device for hydroforming according to the preamble of claim 1.

From the German patent application with the official file number 103 49 699.8 from October 24, 2003, which was not yet published at the time of the present application, a method and a device for the internal high pressure forming of a circumferentially closed hollow profile are known. The known device has an internal high-pressure forming tool with a sealing device which contains an axial plunger with a section which dips into the hollow profile for holding and sealing an end of the hollow profile which protrudes from the engraving of the forming tool. Furthermore, a high-pressure fluid generation system is provided for expanding the hollow profile by means of high-pressure fluidic internal pressure. The fact that an outer diameter of the axial plunger on the immersing section is equal to or slightly less than the inner diameter of the hollow profile end and that the sealing device contains at least one clamping jaw and a pressing element which presses the clamping jaws radially onto the hollow profile end when the section of the axial plunger is immersed the hollow profile end is stable. These measures prevent the hollow profile blank from being pulled off the axial stamp during the internal high-pressure forming process and thus reducing or even canceling the sealing effect. Because the hollow profile blank when forming due to the firm, axially immovable hold, the end cannot be drawn into the engraving, on the one hand the original length of the hollow profile blank remains unaffected by the forming and on the other hand no hollow profile blank material can flow into the mold space from the end, so that especially with long forming distances A largely uniform distribution of wall thickness can be achieved at every point of the hollow profile blank.

Generically known from EP 1 152 843 B1 is a device for internal high pressure forming of a hollow profile, which includes a forming tool, a sealing device for holding and sealing an end of the hollow profile which protrudes from the engraving of the forming tool. The sealing device is formed by a section of an axial plunger which dips into the hollow profile and at least one clamping jaw which, when the section of the axial plunger is immersed, presses radially from the outside onto the end of the hollow profile such that the clamping jaw fixes it in a stable position. The clamping jaws are connected to an actuator, which drives it only radially to the hollow profile axis for its adjustment.

From DE 197 51 407 Cl a device for the hydraulic sealing of a hollow profile is known. The device has a die and a tensioning and feed unit as well as several sealing elements closing the hollow profile. In the area of the sealing point, the die, which consists of two die halves, has on the inside a rounded bulge, which extends radially inwards over the circumference, the clamping and feed unit having an axially movable and into the hollow profile by means of a pull-push Element insertable mandrel is provided. This The mandrel is positioned in relation to the die in such a way that the bulges of the die correspond to a correspondingly depicted section of the mandrel. Since the distance from the pipe end is not limited, it can be sealed anywhere in the tool.

DE 38 20 952 C2 discloses a device for the hydraulic expansion of hollow profiles made of a metallic material that are open at the end faces. The open end faces are closed with rigid sealing heads, which enclose the inner or outer surface of the hollow profile closely, but at a distance. An intermediate sealing gap is sealed in an elastic sealing ring, which is designed as a hollow body and can be subjected to internal pressure. In addition, the sealing ring is chambered in the sealing head in such a way that, as a result of the internal pressure, it can only expand in the direction of the outer or inner surface of the hollow profile to be sealed and there comes into tight contact with it. The chambering of the sealing ring means that the elastic material cannot escape laterally. Since the hydraulic expansion pressure is also present in the sealing gap, it is provided that the internal pressure in the sealing ring is always kept above this expansion pressure to such an extent that the contact pressure of the sealing ring on the surface of the hollow profile is always above the expansion pressure, thus ensuring a secure seal.

DE 197 33 473 A1 discloses a method and a device for producing a connection of a hollow cylindrical λ probe holder to an exhaust pipe provided with exhaust gas with an opening for loading the λ probe fastened in the holder. The process uses internal high pressure technology to connect the λ probe holder. In this case, the exhaust pipe is easily adapted to the contour of the lateral surface of the holder by means of high internal pressure at the point at which the future contact surface of the holder is provided. The connection of the holder with its outer surface to the exhaust pipe saves installation space, the holder being at this point, to a certain extent, quasi sunk into the exhaust pipe, but at least sunk into the pipe wall.

The present invention is concerned with the problem of specifying an improved embodiment for a device for hydroforming of the type mentioned at the outset, which in particular ensures that the semifinished ends of the hollow profile are securely held and sealed and at the same time enables high-quality components which have been hydroformed to be produced.

This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of providing an actuator in a device for internal high-pressure forming of a hollow profile, which has a sealing device for holding and sealing an end of the hollow profile protruding from an engraving of the forming tool, which drives a clamping jaw for its adjustment exclusively radially to the hollow profile axis and thereby presses the jaws from the outside onto the hollow profile end in such a way that it is fixed in position. In this way, an improved sealing and holding of the hollow profile end can be achieved. The pressing force is counteracted by a section of an axial plunger which dips into the hollow profile and which is part of the sealing device. device and which supports the hollow profile end from the inside against the clamping jaws pressing from the outside.

The actuator causes jamming and thus holding or sealing of the hollow profile end before the actual forming process, so that the hollow profile blank can be moved into it when the forming tool is open, thereby avoiding or at least reducing possible damage to a surface of the hollow profile blank can be. At the same time, the hollow profile blank is held securely during the entire manufacturing process by the pressure on the axial ram by means of the clamping jaw, which acts radially from the outside. This prevents the hollow profile blank from being pulled off the axial ram during the internal high-pressure forming process, thereby reducing or even canceling the sealing effect.

Since the hollow profile blank cannot be drawn into the engraving or die, on the one hand the original overall length of the hollow profile blank remains unaffected by the shaping and on the other hand no hollow profile blank material can flow into the mold space from the end, so that especially in the case of long forming sections at any point of the hollow profile blanks a largely uniform wall thickness distribution prevails.

The largely uniform distribution of wall thicknesses also ensures problem-free production of a component coil from which, after reshaping, a number of identical components are produced in a subsequent separation process, which have the same or at least similar functional properties due to the uniform distribution of wall thickness. Since the shape of the hollow profile end is not changed by widening by the device according to the invention and at least the inside diameter is also retained, a subsequent end trimming can be omitted, which saves process time and reduces the costs for the entire production process.

According to the solution according to the invention, at least one ring prong is arranged on a side of the clamping jaw facing the hollow profile end. The resulting positive fit not only strengthens the hold of the hollow profile end between the clamping jaws and the axial ram, but also the axial flow of material within the hollow profile end, which prevents the hollow profile from creeping at its end in the direction of the forming tool engraving. The result of this is that lower contact forces have to be applied in order to provide sufficient resistance to the contraction caused by internal high-pressure forming.

According to a preferred embodiment of the invention, the actuator comprises at least one hydraulic cylinder or is formed by at least one hydraulic cylinder. As a result, the clamping jaws can be pressed hydraulically and thus powerfully and precisely onto the hollow profile end. At the same time, hydraulic cylinders represent a drive technology that has been tried and tested over many years and is therefore reliable, so that the actuator can be implemented cost-effectively with regard to operation and maintenance.

According to an advantageous embodiment of the invention, the actuator enables the clamping jaw to be adjusted when the forming tool is open. The forming tool can for example consist of at least two mutually adjustable Die parts are formed, which form the engraving in the closed state. The possibility of adjusting the clamping jaw when the forming tool is open enables the hollow profile blank to be moved into the forming tool without there being any risk of damaging the surface of the hollow profile blank, since the two die parts lie far outside a path of movement of the hollow profile blank. By avoiding or reducing surface damage, particularly high quality requirements can be met.

The die parts of the forming tool can expediently be adjusted while the clamping jaws fix the hollow profile end. This results in a process advantage, since the die parts only have to be moved onto the hollow profile blank immediately before the internal high-pressure forming process, and a damage to the surface of the hollow profile blank by a die contact surface can thereby be avoided. At the same time, this prevents the hollow profile blank end from being pulled in due to pre-profiling in the event that the hollow profile blank is to be squeezed out of the closing movement of the forming tool by a die part and thus pre-profiled.

Further important features and advantages of the invention emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own without departing from the scope of the present invention. Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, the same reference symbols referring to the same or functionally identical or similar components.

Show:

1 shows part of a device according to the invention for internal pressure forming in a starting position,

2 shows a representation as in FIG. 1, but with an axial punch applied to a hollow profile end,

3 shows a representation as in FIG. 2, but with a clamping jaw pressed from the outside onto the hollow profile end,

Fig. 4 is an illustration as in Fig. 3, but with the forming tool closed.

According to FIG. 1, a device 10 for the internal high-pressure forming of a hollow profile 5 has a die 1, a clamping jaw 3 arranged thereon and adjustably mounted thereon, and an axial punch 4. The die 1 is part of a shaping tool, not explained in detail, in which the hollow profile 5 is expanded by internal high pressure and is shaped in accordance with an engraving 16. The clamping jaws 3 and the axial plunger 4 are part of a sealing device 11 which serves to hold and seal an end 12 of the hollow profile 5 which protrudes from the engraving 16 or die 1 of the forming tool. The axial plunger 4 has an immersing section 6 (sealing area) at an end facing the hollow profile end 12, with which the axial punch 4 dips into the hollow section 5.

1 to 4, only a part is shown, for example an upper part in FIGS. 1 and 3 and a lower part of the device 10 in FIGS. 2 and 4.

The axial ram 4 extends from its immersing section 6 to the rest of the ram body step-by-step to form a paragraph, not specified, by means of which the axial ram 4 strikes the hollow profile end 12 while in the use position. The immersed section 6 of the axial punch 4 is dimensioned such that in the position of use (cf. FIGS. 2 to 4) it comes to lie on a specific extension length in the forming tool. Due to the resulting storage, the axial punch 4 remains centered, which favors the durability of a sealing function.

At least one axial active media channel 7 runs in the axial plunger 4, which is connected on the one hand to a fluid high-pressure generation system (not shown) and on the other hand opens out on an end face 13 of the axial plunger 4. An outer diameter of the axial plunger 4 on the immersing section 6 is expediently dimensioned such that it corresponds to the inside diameter of the hollow profile end 12 or falls slightly short of it, so that the section 6 is free from play, but without plastic expansion of the hollow profile end 12, or with little play in the hollow profile end 12 comes to rest.

1, the sealing device 11 has at least one clamping jaw 3, which is part of the forming tool and which is mounted on the outside of the forming tool so as to be displaceable radially to the hollow profile axis. At least one ring prong 2 is provided on an end face of the clamping jaw 3 facing the hollow profile end 12, which notches and fixes this when the clamping jaw 3 is pressed onto the hollow profile end 12 resting on the immersing section 6. The notch created by the ring spike 2 can be used advantageously, for example, when the hollow profile 5 is used further during a joining operation with other components.

According to the invention, an actuator 14 is provided for actuating the jaw 3 (cf. FIGS. 3 and 4), which drives the jaw 3 only radially to the hollow profile axis for its adjustment. The actuator 14 can be formed by at least one hydraulic cylinder or comprise at least one hydraulic cylinder. Alternatively, it is also conceivable that the actuator 14 is formed by at least one electric motor or comprises at least one electric motor.

In general, the device 2 has at least two mutually adjustable die parts 15, for example an upper die part 15 and a lower die part 15 ^{, λ} , which can be adjusted towards or away from one another independently of the clamping jaw 3. 1 to 3 it is shown that the actuator 14 enables the jaw 3 to be adjusted when the forming tool is open.

In order to enable an independent adjustment movement of the clamping jaw 3 from the die part 15, the clamping jaw 3 according to FIG. 3 can, for example, be supported on the forming tool, that is to say on the die part 15 ^λ , while the die part 15 is supported on a foundation 9. However, it is also conceivable that, according to FIG. 4, both the clamping jaw 3 and the die part 15 ′ of the forming tool are supported independently of one another on the foundation 9. I »

In principle, it is conceivable that the jaws 3 are carried axially. This ensures controllable and / or controllable material tracking during the forming process, as a result of which the quality of the hollow profile 5 produced can be increased. The clamping jaws 3 can either be carried passively or via a non-illustrated, for example force-controlled, actuator which enables the clamping jaws 3 to be set relative to the die parts 15 axially to the hollow profile 5.

The process sequence during the clamping or hydroforming process is briefly explained below:

At the beginning of the process, the hollow profile 5 is inserted into the lower die part 15 ^{, λ of} the forming tool, whereupon the section 6 of the axial punch 4 according to FIG. 1 is pushed into both ends, here in the end 12 of the hollow profile 5, until the latter Heel strikes at the end of the hollow profile 12. Alternatively, it is conceivable that the immersing section 6 is inserted in advance into the hollow profile 5 and this is then moved between the two die parts 15 and 15 ^λ .

Thereafter, in a second method step according to FIG. 2, the clamping jaw 3 is pressed radially from the outside onto the hollow profile end 12 by means of the actuator 14 and thereby fixed in position on the immersed section 6 of the axial plunger 4. By moving the jaw 3 in Direction of the direction of movement 8 ^X towards the hollow profile end 12, this is notched by the pressing force exerted by the actuator 14 through the ring spike 2. It is generally conceivable that the actuator 14 for adjusting the die parts 15 ^v and 15 ^{, x} or the clamping jaws 3 is designed as a hydraulic or as an electromechanical actuator.

The embodiment of the ring spike 2 shown in FIGS. 1 to 4 represents only one possible variant, wherein clamping jaws 3 without ring spikes 2 are also conceivable. In this case, the jaw 3 is frictionally connected to the hollow profile end 12 to form a press fit and thereby sealed.

3, the clamping process and thus the sealing process is completed by the radial pressing of the clamping jaw 3 against the hollow profile end 12 and the hollow profile 5 is fixed in position in the device 10. Now the actuator 14 ^λ adjusts the die part 15 ′ in the direction of movement 8 ″ toward the hollow profile 5. It is conceivable here that either only the upper die part 15 or else the upper and the lower die part 15 ', 15 ^{, λ} perform a closing movement. The two die parts 15 'and 15''are moved towards each other until the two die parts 15 15 ^vx come to rest on the hollow profile 5 outside the engraving 9. The die parts 15 'and 15 ^{, v} are adjusted while the jaws 3 fix the hollow profile end 12. The clamping action of the clamping jaws 3 prevents the hollow profile end 12 from being drawn into the engraving 16 by the upper die part 15 'during the closing movement. According to FIG. 4, the closing process of the forming tool is now completed, so that the hollow profile 5 can be filled with a pressure fluid via the at least one active media channel 7 by means of the fluid high pressure generation system, not shown. The pressurized fluid is then tensioned to an internal high pressure, as a result of which the hollow profile 5 expands and lies against the inner wall of the engraving 16 true to the contour. During the expansion, the jaws 3 prevent the hollow profile end 12 from being drawn into the engraving 16 and simultaneously seal the hollow profile end 12. After the internal high-pressure forming has been carried out, the die parts 15 ^v and 15 ^v> and then the clamping jaws 3 are first moved back or opened, so that the completely formed hollow profile 5 can be removed by retracting the axial punch 4.

Claims

claims

1. Device (10) for the internal high pressure forming of a hollow profile (5), - with a forming tool, - with a sealing device (11) for holding and sealing an end (12) of the hollow profile (5) protruding from the engraving (16) of the forming tool, - The sealing device (11) has a section (6) of an axial plunger (4) which is immersed in the hollow profile (5) and at least one clamping jaw (3) which, when the section (6) of the axial plunger (4) is immersed, radially in such a way presses on the outside of the hollow profile end (12), that the clamping jaws (13) fixes it in a stable position - and is provided with an actuator (14) which drives the clamping jaws (3) only radially to the hollow profile axis for its adjustment, characterized in that at one at least one ring prong (2) is arranged on the side of the clamping jaw (3) facing the hollow profile end (12).

2. Device according to claim 1, characterized in that the actuator (14) is formed by at least one hydraulic cylinder or comprises at least one hydraulic cylinder.

3. Device according to claim 1 or 2, characterized in that the actuator (14) is formed by at least one electric motor.

4. Device according to one of claims 1 to 3, characterized in that the forming tool is formed from at least two mutually adjustable die parts (15, 15 ', 15 ").

5. Device according to one of claims 1 to 4, characterized in that the clamping jaws (3) is mounted radially adjustable to the hollow profile axis on the forming tool.

6. Device according to one of claims 1 to 5, characterized in that the actuator (14) allows an adjustment of the clamping jaw (3) when the forming tool is open.

7. Device according to one of claims 1 to 6, characterized in that the forming tool is designed so that the die parts (15, 15 ', 15' ") can be adjusted while the jaws (3) fixes the hollow profile end (12) ,

8. Device according to one of claims 1 to 7, characterized in that the clamping jaws (3) are supported on the forming tool, while the forming tool is supported on a foundation (9).

9. Device according to one of claims 1 to 7, characterized in that the clamping jaws (3) and the forming tool are each supported on a foundation (5).

10. Device according to one of claims 1 to 9, characterized in that the clamping jaws (3) can be carried axially.