AT525767A2 - INTERNAL HIGH PRESSURE FORMING TOOL DEVICE AND METHOD FOR MANUFACTURING A HOLLOW BODY BY INTERNAL HIGH PRESSURE FORMING - Google Patents

Abstract

The invention relates to an internal high-pressure forming tool device (10), a method and a corresponding computer program product for producing a hollow body from a pre-bent tubular blank (12) by internal high-pressure forming of at least one part (14, 16) of a central section (18) of this blank (12), with - tool parts (34) for forming a cavity (36) that determines the final shape of the hollow body, - a high-pressure system (42) for pressurizing the interior (44) of the blank (12) with a pressure medium, the high-pressure system (42) having sealing stamps (48 , 50) for sealing the blank (12) at the end in a pressure-tight manner, - a control/regulating device (64) for controlling/regulating the hydroforming process and - clamping devices (56, 58) for fixing an end section (22, 24) of the blank ( 12), the end sections (22, 24) being fixed on the tool side by the clamping device (56, 58) before or during the pressure-tight closure using a sealing stamp (48, 50) and the end section (22, 24) being fixed by the corresponding clamping device ( 56, 58) is released before or at the latest during the pressurization.

Description

Hydroforming tool apparatus and method of making one

Hollow body by hydroforming

The invention is based on an internal high-pressure forming tool device for producing a hollow body from a pre-bent tubular blank by internal high-pressure forming of at least one central section of this blank, with (i) at least two tool parts for the joint formation of a cavity that determines the final shape of the hollow body, (ii) a high-pressure system for Pressurization of the interior of the blank with a pressure medium, the high-pressure system having at least one sealing die for pressure-tight sealing of the blank at at least one of the ends and (iii) a control and/or regulating device for controlling/regulating the internal high-pressure forming

process.

The invention is also based on a method for producing a hollow body from a pre-bent tubular blank by internal high-pressure forming of at least one central section of this blank using an internal high-pressure forming tool device with at least two tool parts for the joint formation of a cavity that determines the final shape of the hollow body and a high-pressure system for pressurizing the interior of the blank with a pressure medium, this high-pressure system having at least one sealing die for pressure-tight sealing of the blank at at least one of the ends, and the method comprising the following steps:

(a) inserting the blank into the hydroforming tool device,

(b) filling the blank with the pressure medium,

(c) pressure-tight sealing of the blank by means of the at least one sealing stamp and

(d) Pressurizing the interior of the blank with a high-pressure system.

Finally, the invention is also based on a corresponding

Computer program product for carrying out the method.

In such a production of a hollow body from a pre-bent

tubular blank comes on the inwardly curved, i.e. concave, side

the bending often leads to undesirable wrinkling during hydroforming. This happens in particular when—for example due to the axial tracking of material—a material compression occurs on the inner bend.

This phenomenon is also described in publication EP 1 034 053 B1 in connection with a method for producing a hollow body from a pre-bent tubular blank by hydroforming at least a central section of this blank using a hydroforming tool device. The tool device comprises at least two tool parts for the joint formation of a cavity that determines the final shape of the hollow body and a high-pressure system for pressurizing the interior of the blank with a pressure medium, this high-pressure system having pressure pistons for pressure-tight sealing of the blank at the ends. The method comprises the following steps: (a) loading the blank into the hydroforming tooling apparatus, (b) pressure-sealing the blank using the plunger(s), and (c) pressurizing the interior of the blank with the high-pressure system. In the document it is proposed to apply a force to at least one of the ends along the end section, whereby a part of this force acting on the concave side is selected to be smaller than a part of this force acting on the opposite convex side. In this way, the formation of wrinkles can be prevented or at least reduced. However, the partial forces must be adjusted very precisely to the wall thickness of the blank and the change in cross-sectional area during hydroforming.

Such an adjustment is quite complex.

A further reason for the occurrence of said wrinkling can, however, be the forces that occur when the blank is closed by means of the sealing stamp(s). Even when the sealing stamp is inserted into the end of the blank or the sealing stamp into the end of the blank up to the point of sealing, such high forces often occur that the concave side of the

bend creases arise.

It is an object of the invention to provide a hydroforming tool device for

Production of a hollow body by hydroforming, a method for

Production of a hollow body by internal high-pressure forming and a corresponding computer program product in which such an undesirable formation of wrinkles in the area of the bend of the pre-bent tubular blank in connection with the internal high-pressure forming is reliably prevented or

at least reduced.

The object is achieved according to the invention by the features of the independent claims. Preferred configurations of the invention are specified in the dependent claims, each of which individually or in combination defines an aspect

of the invention can represent.

In the hydroforming tool device according to the invention for producing a hollow body from a pre-bent tubular blank by hydroforming at least part of a middle section of this blank, which

(i) at least two tool parts for the joint formation of a cavity that determines the final shape of the hollow body,

(il) a high-pressure system for pressurizing the interior of the blank with a pressure medium, the high-pressure system having at least one sealing die for sealing the blank in a pressure-tight manner at at least one of its ends and

(ii) comprises a control and/or regulating device for controlling/regulating the hydroforming process

it is envisaged that this tool device continues

(iv) one or more clamping devices, each for the optional tool-side fixing of an end section of the blank located at a respective end, wherein the control and/or regulating device is set up to clamp the end section or end sections using the corresponding clamping device(s). ) before or during the pressure-tight closing by means of a sealing stamp on the tool side and to loosen the fixing of the end section or at least one of the end sections by the corresponding clamping device before or at the latest during the pressurization. In this way it can be prevented that the insertion of the individual sealing die into the corresponding end of the blank and the resulting pressure-tightness are prevented

Closing the blank leads to the formation of wrinkles in the bending area of the blank.

The hydroforming tool device is set up in particular to carry out the following steps:

Filling the blank previously placed in the hydroforming tool device with the pressure medium,

pressure-tight sealing of the blank by means of the at least one sealing stamp, temporary fixing of one or both end sections during pressure-tight sealing by means of the clamping device/clamping devices and

pressurizing the inside of the blank by high-pressure system,

the fixing of the end section or at least one of the end sections by the at least one corresponding clamping device on the one hand after the pressure-tight sealing by means of a sealing plunger, but on the other hand before or

is released at the latest during the pressurization.

The optional tool-side fixing of the respective end section of the blank by means of the corresponding clamping device is based on force and/or

Form fit between at least one clamping jaw of the clamping device and a lateral surface of the corresponding end section of the blank. In particular, at least one indentation is formed in this lateral surface by gripping the clamping jaw

formed, in which the jaw engages for fixing.

According to a preferred embodiment of the invention, the hydroforming tool device has at least one actuator for actively tracking the at least one sealing die along the longitudinal axis of the corresponding end section in the direction of the middle section. To do this, the actuator moves the corresponding sealing die in said direction. It is usually also used to seal the blank in a pressure-tight manner using the sealing stamp by pushing the sealing stamp into the corresponding end of the blank up to

plugged into a sealing position.

It is preferably provided that the control and/or regulating device is also set up for controlling/regulating the active tracking of the corresponding end section, in particular as a function of the internal pressure in the blank/hollow body. For this purpose, the hydroforming tool device has, in particular, a pressure measuring device for measuring the internal pressure of the blank

or hollow body.

Furthermore, it is preferably provided that the high-pressure system is designed in such a way that the pressure medium flows via the sealing stamp or one of the sealing stamps into the

Interior of the blank can be initiated.

In particular, the clamping device or at least one of the clamping devices is set up to deform the blank in the corresponding end section. A particularly firm fixation of the end section of the blank can be based on this

a force and/or form closure can be guaranteed.

According to a further preferred embodiment of the invention, the cavity has two elongated areas for receiving the end sections of the blank, the longitudinal axes of which are arranged at an angle a=25° and/or have an offset that corresponds at least to the size of the diameter dr of the blank. With such an arrangement of the end sections you can usually one

(before) speaking bent tubular blank.

According to a further preferred embodiment of the invention, the cavity is set up to accommodate a pre-bent tubular blank with at least one bend in which the ratio of the diameter dr of the blank to

bending radius rg is less than or equal to 3, i.e. dr/re <= 3.

In the method according to the invention for producing a hollow body from a pre-bent tubular blank by internal high-pressure forming of at least one central section of this blank by means of an internal high-pressure forming tool device, which has at least two tool parts for the joint formation of a cavity that determines the final shape of the hollow body, a high-pressure system for pressurizing the interior of the blank with a pressure medium , wherein this high-pressure system has at least one sealing plunger for pressure-tight sealing of the blank at at least one of its ends and one or more clamping devices, each for selectively tool-side fixing of an end section of the blank located at the respective end, it is provided that the method comprises the following steps :

(a) inserting the blank into the hydroforming tool device,

(b) filling the blank with the pressure medium,

(c) pressure-tight sealing of the blank by means of the at least one sealing die,

(d) at least temporarily fixing one or both end sections by means of the clamping device/clamping devices and

(e) pressurizing the interior of the blank with a high-pressure system,

wherein the temporary tool-side fixing of one or at least one of the two end sections is effected by the corresponding clamping device during the pressure-tight closure and the fixing of the end section or at least one of the end sections is released by the at least one corresponding clamping device before or at the latest during the pressurization. This prevents the insertion of the individual sealing stamp into the corresponding end of the blank and the resulting pressure-tight sealing of the blank from leading to the formation of creases in the bent area of the blank. In particular, a control and/or regulating device is provided for controlling/regulating the hydroforming process. This is in particular a computer or

processor-based control and/or regulating device.

It is advantageously provided that during hydroforming, the at least one end section, in particular via the respective sealing stamp, in the direction of the

Middle section is actively tracked.

According to a preferred embodiment of the method according to the invention, the blank is fixed by means of the clamping device or at least one of the

Clamping devices deformed in the corresponding end section.

The optional tool-side fixing of the respective end section of the blank by means of the corresponding clamping device is preferably based on a frictional and/or positive connection between at least one clamping jaw of the clamping device and a lateral surface of the corresponding end section of the blank. In this lateral surface is by grabbing the jaw in particular at least

formed a depression into which the clamping jaw engages for fixing.

In the computer program product according to the invention it is provided that this

includes instructions which, when executed by a processor of a control and/or regulating device, cause this processor to be mentioned above

carry out procedures.

In the following, the invention is explained by way of example with reference to the attached drawings using preferred exemplary embodiments, the features presented below both individually and in combination

may represent an aspect of the invention. Show it:

Fig. 1 is a schematic overall representation of an internal high-pressure forming

Tool device according to a preferred embodiment of the invention and

2 shows a representation of part of an internal high-pressure forming tool device according to a further preferred embodiment of the

Invention.

Fig. 1 shows a schematic representation of an internal high-pressure forming tool device 10 for producing a hollow body from a pre-bent tubular blank 12 by internal high-pressure forming of at least one part (in the example two parts) 14, 16 of a middle section 18 of this blank 12. The middle section 18 of the pre-bent tubular blank 12 has a bend 20 in the example shown. Alternatively, however, the middle section 18 could also have a plurality of bends 20--for example running in opposite directions. A straight end section 22 , 24 of the blank 12 follows on each side of the middle section 18 and extends along a respective longitudinal axis 26 , 28 to a respective end 30 , 32 of the blank 12 . Due to the bend 20 in the middle section 18, the two longitudinal axes 26, 28 of the end sections 22, 24 are arranged inclined at an angle α of approximately 30° to one another. 1 shows the situation before hydroforming.

Accordingly, (only) the blank 12 is also shown here.

The hydroforming tool device 10 has two tool parts 34 for the joint formation of a cavity 36 that determines the final shape of the hollow body, of which only one tool part 34 is shown here in FIG. In cavity 36

is the blank 12, so that only areas 38, 40 of the cavity 36 remain free. In

these free areas 38, 40 of the cavity 36, the parts 14, 16 of the middle section 18 of the blank 12 are expanded during hydroforming. The shape of the formed blank 12 after hydroforming is here

based on the overall shape of the cavity 36 so already recognizable.

Furthermore, the hydroforming tool device 10 has a high-pressure system 42 for pressurizing the interior 44 of the blank 12 with a pressure medium. This pressure medium is usually a liquid, but can also be a gas such as N2. The high-pressure system 42 in turn has a pressure measuring device 46 and two sealing dies 48, 50 for pressure-tight sealing of the blank 12 at the two ends 30, 32 and two actuators 52, 54 for actively moving the sealing dies 48, 50 along the longitudinal axes 26, 28 of the corresponding end sections 22, 24, especially for

active tracking in the direction of the middle section 18 on.

Furthermore, hydroforming tool device 10 comprises two clamping devices 56, 58, each for selectively fixing one of the two end sections 22, 24 of blank 12 on the tool side. Each of clamping devices 56, 58 in turn comprises a clamping jaw 60 and an actuator 62 for moving the respective clamping jaw 60 transverse to the longitudinal axis 26, 28 of the respective end section 22, 24. Of course, several (for example two) clamping jaws

60 per clamping device 56, 58 may be provided (as shown in the example of FIG. 2).

Finally, the hydroforming tool device 10 has a control and/or regulating device 64 for controlling/regulating the hydroforming process. This control and/or regulating device 64 controls in particular the actuators 50, 52, 62 and regulates the pressurization of the interior 44 of the blank 12 with the pressure medium via the high-pressure system 42 with its pressure measuring device 44. This is the control and/or regulating device 64 set up to fix the end sections 22, 24 by the clamping devices 56, 58 before or during the pressure-tight closure by means of sealing stamps 48, 50 on the tool side and the fixing of the end sections 22, 24 by the clamping devices 56, 58 before or at the latest during the pressurization of the interior 44 of the blank 12 to solve. From a line system 66 of the high-pressure system 42 is

only a small part is shown here. This part of the line system 66 is used

Supply of the pressure medium into the interior of the blank 12 and leads as a channel

through the sealing stamp 48.

The procedure for producing a hollow body from a pre-bent tubular blank 12 by hydroforming at least one middle section 18 of this blank 12 with the aid of the previously

described hydroforming tool device 10:

First, the pre-bent tubular blank 12 in the

Internal high-pressure forming tool device 10 is inserted, more precisely the blank 12 is inserted into one tool half 34 and the two tool halves 34 are then closed around the blank 12. Then the print medium is inserted into the

Inner 44 of the blank 12 filled. This is done using the high-pressure system 42.

The blank 12, more precisely the interior 44 of the blank 12, is then sealed in a pressure-tight manner by means of the two sealing dies 48, 50. To do this, each of the two sealing stamps 48, 50 is moved by means of the respectively assigned actuators 52, 54 for actively moving the sealing stamps 48, 50 along the longitudinal axes 26, 28 of the corresponding end sections 22, 24 in the direction of the central section 18 of the blank 12 until each of the Sealing stamp 48, 50 in each one of the ends 30, 32 retracts. At this point in time at the latest, the two end sections 22, 24 are temporarily fixed on the tool side by means of the clamping devices 56, 58. For this purpose, the sealing stamps 48, 50 are moved by means of the actuators 52, 54 in the direction of the respective longitudinal axis 26, 28 until a frictional and/or form fit occurs with the respective end section 22, 24 of the blank. This can result in deformation, in particular plastic deformation, of the blank 12 as a result of the respective sealing stamp 48, 50. Then each of the sealing stamps 48, 50 is moved further into the respective end 30, 32 until it finally seals the blank 12, more precisely the interior of the blank 12, via its conical lateral surface.

sealed pressure-tight to the outside. Now the fixing of the end sections 22, 24 by the clamping devices 56,

58 solved again by the actuators 52, 54, the sealing stamp 48, 50 transversely to

respective longitudinal axis 26, 28 move outwards again.

10

The interior 44 of the blank 12 is then pressurized by the high-pressure system 42 with the aid of the pressure medium. The pressure medium is usually a liquid. The pressure is in the order of one to several thousand bar (usually 500 - 4000 bar). During hydroforming, the sealing stamps 48, 50 and with the sealing stamps also the end sections 22, 24 are actively tracked in the direction of the middle section 18. The active tracking of the end sections 22 , 24 takes place as a function of the internal pressure in the blank 12 , this internal pressure being determined by the pressure measuring device 46 . The pressure is applied via a line system of the high-pressure system 42, of which only a part installed in/on the sealing plunger 48 is shown in FIG. By applying pressure, the blank is attached to the areas of the tool parts 34

pressed, which limit the cavity 36 and thus form a kind of shape.

Finally, the pressure is released, the sealing stamps 48, 50 are moved out of the ends 30, 32, the tool parts 34 are opened again and the formed blank or hollow body can be subjected to the internal high-pressure

Tool device 10 are removed.

In most cases, only part of the formed blank/hollow body is used for further processing to form an end product, namely the middle section 18 or a section of the middle section 18, in which the parts 14, 16 of the middle section and possibly also the bend 20 are located. The remainder, ie in particular the end sections 22, 24, is completely severed in these cases

and removed.

Fig. 2 shows part of another hydroforming tool device 10 for producing a hollow body from a pre-bent tubular blank 12 by hydroforming at least part 14 of the middle section 18 of this blank 12. The part shown here is practically half of the hydroforming tool device 10 and ranges from the one sealing die, of which only one (sealing) level 68 is shown here, up to the central area of the cavity 36, which serves to accommodate the bend 20 of the blank 12. Here, too, the pre-bent tubular blank 12 is in a tool part

34 inserted.

11718

11

In this specific example, the interaction between the clamping device 56 and the lateral surface of the blank 12 in the end section 22 can be seen more clearly. The clamping device 56 has two clamping jaws 60 arranged opposite one another. The same applies to the other clamping device (not shown).

at the other end portion 24 of the blank 12.

In the lateral surface of the blank 12 in the end section 22, two slight indentations are formed (only one of which is visible here), in which the clamping jaws 60 can each engage for fixing. When the blank 12 is fixed by means of the clamping device 56, a positive and non-positive connection is thus created. In the area of the connection between the respective clamping jaw 60 and the lateral surface of the tubular blank 12, the wall of the blank 12

Stress and / or deformation areas 70 from.

Hydroforming now results in the following time sequence:

Phase |: 0...40 s: pre-bent tubular blank 12 is in the closed tool (upper tool part is hidden, lower tool part 34 is visible);

Phase II: 40...45 s: jaws 60 move from above and below into the tubular blank 12 and establish a form fit (over a deformed area at the end portion 22, 24 of the blank 12);

Phase III: 45 . . . 55 s: sealing die 48, 50 (ideally drawn as a transparent plane 68 at the end 30) moves into the respective end 30, 32 of the blank 12 and seals it. This prevents material from being pushed in an uncontrolled manner into the adjacent area of the bend 20 and possibly leading to irreversible fold formation there;

Phase IV: 55...60 s: retraction of the jaws 60; and

Phase V: 60... 135 s: Actual forming process with a controlled characteristic

Internal pressure/axial travel sealing stamp 48, 50.

12

References:

10 hydroforming tool fixture 12 blank

14 part (middle section)

16 part (middle section)

18 middle section

20 bend

22 end section

24 end section

26 longitudinal axis

28 longitudinal axis

30 end

32 end

34 tool part 36 cavity

38 area (cavity)

40 area (cavity)

42 high pressure system

44 interior

46 pressure gauge

48 sealing stamp

50 sealing stamps

52 actuator

54 actuator

56 clamping device

58 clamping device

60 jaw

62 actuator

64 control and/or regulating device 66 line system

68 level (sealing stamp)

70 areas of stress and/or deformation a angle

Claims (10)

13 patent claims A hydroforming tool device (10) for producing a hollow body from a pre-bent tubular blank (12) by hydroforming at least a part (14, 16) of a central section (18) of this blank (12), with - at least two tool parts (34) for the joint formation of a cavity (36) that determines the final shape of the hollow body, - A high-pressure system (42) for pressurizing the interior (44) of the blank (12) with a pressure medium, the high-pressure system (42) having at least one sealing die (48, 50) for sealing the blank (12) in a pressure-tight manner at at least one of its ends ( 30, 32) has, - a control and/or regulating device (64) for controlling/regulating the hydroforming process and - one or more clamping devices (56, 58), each for the selective tool-side fixing of an end section (22, 24) of the blank (12) located at a respective end (30, 32), wherein the control and/or regulating device (64) is set up to fix the end section or end sections (22, 24) on the tool side by means of the corresponding clamping device (56, 58) before or during the pressure-tight sealing by means of a sealing die (48, 50) and the fixing of the end section or at least one of the end sections (22, 24) by the corresponding clamping device (56, 58). or to solve at the latest during the pressurization. 2. Hydroforming tool device according to Claim 1, characterized by at least one actuator (52, 54) for actively tracking the at least one sealing die (48, 50) along the longitudinal axis (26, 28) of the corresponding end section (22, 24) in the direction of the middle section (18). 3. Internal high-pressure forming tool device according to claim 2, characterized in that the control and/or regulating device (64) is also used to control/regulate the active tracking of the corresponding end section (22, 24), in particular as a function of the internal pressure in the blank/hollow body. is set up. 14 4. Hydroforming tool device according to one of claims 1 to 3, characterized in that the clamping device or at least one of the clamping devices (56, 58) is set up for deforming the blank (12) in the corresponding end section (22, 24). 5. Hydroforming tool device according to one of claims 1 to 4, characterized in that the cavity (36) has two elongated areas for receiving the end sections (22, 24) of the blank (12), whose longitudinal axes (26, 28) in one Angle a = 25 ° are arranged and / or have an offset that corresponds at least to the size of the diameter dr of the blank (12). 6. A method for producing a hollow body from a pre-bent tubular blank (12) by internal high-pressure forming of at least one middle section (18) of this blank (12) using an internal high-pressure forming tool device (10), with at least two tool parts (34) for jointly forming the final shape of the hollow body defining cavity (36), with a high-pressure system (42) for pressurizing the interior (44) of the blank (12) with a pressure medium, this high-pressure system (42) having at least one sealing stamp (48, 50) for pressure-tight sealing of the blank (12) at least one of its ends (30, 32) and with one or more clamping devices (56, 58), each for selective tool-side fixing of an end section (22, 24) of the blank (12) located at the respective end (30, 32) , the method comprising the following steps: - Inserting the blank (12) in the hydroforming tool device (10), - filling the blank (12) with the pressure medium, - pressure-tight sealing of the blank (12) by means of the at least one sealing stamp (48, 50), - at least temporarily fixing one or both end sections (22, 24) by means of the clamping device/clamping devices (56, 58) and - Pressurizing the interior (44) of the blank (12) by means of a high-pressure system (42), with the tool-side temporary fixing of one or at least one of the two end sections (22, 24) being effected by the corresponding clamping device (56, 58) during the pressure-tight closure and the fixation of the end portion or at least one of the end sections (56, 58) by the at least one corresponding one 15 Clamping device (56, 58) before or at the latest during the Pressurization is released. 7. The method according to claim 6, characterized in that during hydroforming the at least one end section (22, 24), in particular via the respective sealing die (48, 50), is actively tracked in the direction of the middle section (18). 8. The method according to claim 6 or 7, characterized in that the blank (12) when fixing by means of the clamping device or at least one of the clamping devices (56, 58) in the corresponding end section (22, 24) - in particular plastic - is deformed. 9. The method according to any one of claims 6 to 8, characterized in that the optional tool-side fixing of the respective end section (22, 24) of the blank (12) is based on a frictional and/or positive connection between at least one clamping jaw (60) of the clamping device (56 , 58) and a lateral surface of the corresponding end section (22, 24) of the blank (12). 10. A computer program product comprising instructions, which when executed by a processor of a control and/or regulating device (64) cause this to enter A method according to any one of claims 6 to 9 to be carried out.