EP2205370A1

EP2205370A1 - Process and apparatus for producing a hollow body, and hollow body

Info

Publication number: EP2205370A1
Application number: EP08838645A
Authority: EP
Inventors: Thomas Flehmig; Jörg GORSCHLÜTER; Oliver Mertens
Original assignee: ThyssenKrupp Steel Europe AG
Current assignee: ThyssenKrupp Steel Europe AG
Priority date: 2007-10-18
Filing date: 2008-10-17
Publication date: 2010-07-14
Anticipated expiration: 2028-10-17
Also published as: ES2401306T3; EP2205370B1; US20100294014A1; DE102007050337B4; WO2009050270A1; DE102007050337A1; US9283602B2

Abstract

The invention relates to a process for producing a hollow body from metal, said hollow body having at least one first axial portion with a first cross-sectional area and a second axial portion with a second cross-sectional area, and in which the two axial portions of the hollow body are connected to one another by means of a shape transition running in the axial direction, wherein a preform body having at least one transition region which extends in the axial direction of the hollow body to be produced and is arranged between the first axial portion and the second axial portion is produced, wherein, in the transition region, the cross-sectional area of the preform body preferably continuously changes from the cross-sectional area of the first axial portion into the cross-sectional area of the second axial portion, the preform body (1) is accommodated in a die (5), wherein the die (5) has the final external shape of the hollow body to be produced, a shaping mandrel (7) is inserted into the preform body (1), wherein the shaping mandrel (7) has the internal shape of the hollow body to be produced, and an axial movement of the shaping mandrel (7) upsets the preform body (1) in the die (5) into the final shape of the hollow body. In addition, the invention relates to an apparatus for carrying out the process.

Description

METHOD AND DEVICE FOR PRODUCING A HOLLOW BODY AND HOLLOW BODY

The invention relates to a method for producing a hollow body made of metal, which has at least one first axial section with a first cross-sectional area and a second axial section with a second cross-sectional area and in which both axial sections of the hollow body are connected to one another via a form transition running in a radial plane. Moreover, the invention relates to a device for carrying out the method.

Hollow bodies are frequently required in motor vehicle construction and in pipeline construction, which have large cross-sectional shape changes in the axial direction of only short axial lengths, for example from a small cross section to a large cross section. The shape transition between the different cross-sectional shapes having axial portions of these hollow body therefore extends substantially in a radial plane. As a typical example, an exhaust system of a motor vehicle can be considered, which has a correspondingly executed hollow body in the region of the silencer. Other hollow bodies are, for example, support ends of a frame structure of a motor vehicle or fittings of piping systems. All of these hollow bodies are often produced by a plurality of interconnected, in particular welded, sheets, which have been formed into a corresponding hollow body. The strength of the hollow body thus produced is due to the variety the weld] edoch but worthy of improvement. In addition, weld are susceptible to corrosion and increase the cost of manufacturing. In addition, a variety of manufacturing methods are known to produce, for example, from a tubular body corresponding hollow body with strongly stepped shape transition. For example, the printing of sheet blanks or thermoformed preform bodies also allows radially extending Formubergange. However, these Formubergange can usually be made only at the pipe ends and lead to a strong thinning of the sheet thickness. The same applies to the hydroforming, which requires additional high investments in the field of tools. For example, the known Einrolltechnik for the production of hollow bodies of any cross-section of metal from a circuit board allows only the production of mold bypasses, which extend axially over a longer transition region. Forming transversely extending in a radial plane can not be produced by using the rolling-in technique. Finally, by a hot forming m a radial plane extending shape transition can be made. However, this method is also expensive, in particular due to the necessary heating.

Japanese Patent Application Publication JP 2005279706 A moreover discloses a method for producing a hollow body with a shape transition, in which an axial section having a reduced cross-sectional area is drawn out of a region having a larger cross-sectional area by a forming die inserted into the hollow body. On the one hand, in the process of the shape transition between the smaller and larger cross-section is not affected, but rather pulled the smaller cross-sectional area. In addition, the sheet thickness decrease in the known method is relatively large.

On this basis, the present invention seeks to provide a method and an apparatus for producing a generic hollow body available, which or which can be operated economically and with which or with which a high strength having hollow body with substantially in one Radial level extending shape transitions and almost constant sheet thickness can be produced.

According to a first teaching of the present invention, the above-mentioned object is procedurally achieved in that a preform body is produced, which has at least one extending in the axial direction of the hollow body to be produced, arranged between the first and second axial section transition region, wherein in the transition region, the cross-sectional area of the preform body from the cross-sectional area of the first axial portion into the cross-sectional area of the second axial portion, preferably continuously changing, the preform body is received in a die, wherein the die has the final outer shape of the hollow body to be produced, a forming mandrel is inserted into the preform body, wherein the forming mandrel Has inner shape of the hollow body to be produced and is compressed by an axial movement of the mandrel of the preform body in the die in the final shape of the hollow body. It has surprisingly been found that in the erfmdungsgemaßen method, the sheet thickness decrease is minimal, since during the formating of the molding transition or by the compression of the transition region of the preform a material flow is generated, which significantly reduces the sheet thickness decrease m strongly deformed areas. The hollow body produced in this way, with a shape transition between two axial sections extending essentially in a radial plane, has a very homogeneous sheet metal thickness. On the one hand, the hollow body can be carried out very economically on the other hand, owing to the two-step process, namely the preparation of the preform body and the compression molding of the preform body, on the other hand, the resulting hollow body has very good properties in terms of stability. In the present patent application, any shape transition that has a deviation of not more than +/- 20 ° from the perpendicular to the axial direction is regarded as a shape transition that essentially proceeds in a radial plane. The shape transition running essentially in a radial plane takes place according to the invention between axial sections of the hollow body having different cross-sectional areas, ie axial sections having a small cross-section and / or between different cross-sectional shapes, such as axial and polygonal axial sections of the hollow body.

The axial lengths of the axial sections of the hollow body to be produced with different cross-sectional areas can have different lengths, preferably a division of for example, 1/3 to 2/3, wherein 1/3 of the length refers to larger cross-sectional areas. With the known methods, it has hitherto often only been possible to introduce, in end regions, radially extending moldings, for example into a tubular body. In order to further increase the cost-effectiveness of the inventive method, it is preferably provided that the preform body is produced from at least one circuit board, for example using the rolling-in technique or by U-forming. Both methods, the roll-in technique and the UO-forming, have already been tested and allow an economical production of hollow bodies, which can be used as Vorformkorper. Both in the roll-in technique and in the UO-forming, the formed board is welded together in the edge area. In particular, the preformed bodies produced by these processes continue to have very good forming properties owing to the mateπalschonenden pre-treatment. In the second process step, the die upsetting, this also allows large degrees of deformation to be achieved.

Preferably, the length of the transition region of the preform body is selected depending on the wall thickness of the formed board, the shape change in the shape transition and depending on the material. As a result, the process reliability of the erfmdungsgemaßen method further increased and in particular the sheet thickness change can be controlled by the erfmdungsgemaße method. In order to achieve maximum degrees of deformation, the manufacturability of the preform body by means of rolling-in technique or UO-forming should additionally be given. The inventive method is particularly advantageous if the preform body has the outer and inner shape of the hollow body to be produced in at least one axial section. As a result, the upsetting is particularly simple, since the mandrel can be arranged in a simple manner displaceable m this axial portion of the preform. Preferably rohrformige Vorformkorper be reshaped, so that in a simple way Fittmge or parts of exhaust systems or support ends of a frame structure of a motor vehicle are produced.

According to a further embodiment of the method according to the invention, functional elements or secondary shaping elements are introduced into the hollow body to be produced, so that the subsequent introduction of these elements can be dispensed with. Preferably, the introduction of the functional elements and / or secondary features can be integrated xn the die for producing the Vorformkorpers or xm die for forming the shape of Formgangsgangs as well as in the mandrel itself. Functional elements or secondary features may be, for example, Verpragungen, holes or tabs in the lateral surface of the hollow body. Other functional elements are also conceivable.

In order to provide the necessary strength, blanks made of steel, a steel alloy, in particular made of high-strength steels, are preferably used for producing the preform body. In particular, only the inventive method allows the use of high-strength steel, as a total of no large degrees of deformation for the production of the hollow body are needed. In order to better adapt the hollow body to the application, it is advantageous that the preform body is made of "tailored blanks". "Tailored blanks" are tailored to the particular application, for example, consisting of sheets with different material strengths and / or Mateπalguten sheet blanks.

According to a second teaching of the present invention, the above object is achieved by a device in that a first die for producing a Vorformkorpers is provided from a board using the Einrolltechnik or the UO-forming process, wherein the first die is formed so that the preform body has at least one transition region extending between the first and second axial sections in the axial direction of the hollow body to be produced, and in the transition region the cross-sectional area of the preform body preferably continuously changes from the cross-sectional area of the first axial section into the cross-sectional area of the second axial section, and at least one second A die for receiving the produced preform body is provided with a forming mandrel, the second die having the outer end shape of the hollow body, the forming mandrel the inner end shape of the hollow body to be produced a ufweist and the mandrel is axially displaceable relative to the second die.

With the device according to the invention, the method according to the invention can be carried out in an economical manner, so that the advantages of the inventive method are pointed out with regard to the advantages of the device according to the invention becomes. In addition, the necessary dies for producing the preform body and for upsetting the hollow body in its final form require no high investment and thus contribute to the economy of the process.

Further working steps can be avoided according to a further embodiment of the device according to the invention in that the first and / or the second die and / or the forming mandrel has means for introducing functional and / or secondary shaped elements into the hollow body. These do not have to be introduced by additional steps or devices.

A further advantageous embodiment of the inventive device provides that means for automatically transporting a board in the first die of the device and / or means for inserting the

Vorformkorpers m the second die and / or means for

Removal of the hollow body from the second die are provided. In particular, the agents significantly improve the cycle times for producing the hollow body and, to that extent, lead to a particularly economical method of producing the hollow body.

According to a third teaching of the present invention, the above object is achieved by a hollow body made of metal, which has at least a first axial section with a first cross-sectional area and a second axial section with a second cross-sectional area and wherein both axial sections of the hollow body over a substantially in a radial plane extending form transition with each other connected, thereby solved that this is produced by the erfmdungsgemaßen method and the maximum sheet thickness change, in particular in the range of the shape transition amounts to +/- 15%.

As stated above, the inventive method allows a particularly gentle production of a hollow body with essentially m a radial plane form transition between axial sections of different cross-sectional areas and thus allows particularly small changes in sheet thickness of the hollow body.

Finally, particularly high strength hollow body having a radial shape transition can be made available by the hollow body made of steel, a steel alloy and / or high-strength steel. As stated previously, "tailored blanks" can also be used to produce the hollow bodies, so that adaptation of the hollow body to the loads occurring in the application can be achieved with simultaneous weight optimization. In particular, the use of high-strength steel leads to the hollow body thus produced are adapted to high loads.

There are now a variety of ways the inventive method, the device and the hollow body according to the invention to design and further. For this purpose, on the one hand reference is made to the patent claims 1, 8 and 11 subordinate claims, on the other hand to the description of two exemplary embodiments m connection with the drawing. The drawing shows in Fig. 1 in an axial sectional view of the

Vorformkorper an exemplary embodiment of a erfmdungsgemaß prepared hollow body,

Fig. 2, the second die for form upsetting the

Vorformkorpers an exemplary embodiment of a erfmdungsgemaßen device before the upsetting of Vorformkorpers m a schematic axial section view and

Fig. 3, the die of Fig. 2 after the

Form upsetting the preform body in a schematic Axialschnittansicht.

In Fig. 1, the Vorformkorper 1 is first shown in a schematic, axial sectional view. The preform body has a first axial section 2 with a first cross-sectional area and a second axial section 3 with a second cross-sectional area. The cross-sectional area of the first axial section 2 is smaller than the cross-sectional area of the second axial section 3. In the axially extending transition region 4, which is arranged between the two axial sections 2, 3, the cross-sectional area of the axial section 2 changes to the cross-sectional area of the axial section 3 Exemplary embodiment is the shape transition in the m axial direction extending transition region 4 continuously or linearly. But there are also other Formubergange conceivable. The preform body 1 shown in FIG. 1 can be produced, for example, by the application Einrolltechnik or a UO-forming are produced. In the present case, the preform body, as well as the finished hollow body has a circular cross-section and is therefore particularly simple. As already stated, however, the shape transition can also take place between different cross-sectional shapes.

FIG. 2 now shows, in a schematic, axial sectional view, an exemplary embodiment of a die for shaping the preform body 1 for carrying out the method according to the invention. The die 5 has a die 6, which corresponds to the outer shape of the hollow body to be produced. In the die 5 of FIG. 2, the preform body 1 is already inserted and the forming mandrel 7 is inserted into the preform body 1. The mandrel 7 may additionally comprise, not shown means for introducing functional and / or secondary features in the hollow body. Other means, not shown, for introducing functional elements can also be provided in the die 5, but also in the forming mandrel 7. The forming mandrel 7 is now displaced axially in the direction of the arrow so that the transition region 4 of the preform body 1 is compressed into the forming passage 8 of the hollow body. In this way it is achieved that the sheet thickness change, despite the generation of the radially extending shaping passage 8, remains moderate and insofar an improved hollow body with a radial shape transition 8 can be made available, FIG. 3.

Claims

PATENT APPLICATIONS

1. A process for producing a hollow body

Metal, which has at least one first axial section with a first cross-sectional area and a second axial section with a second cross-sectional area and in which both axial sections of the hollow body are connected to one another via a moulding a radial plane form transition, characterized in that a Vorformkorper is produced, which at least one In the transition region, the cross-sectional area of the preform body of the cross-sectional area of the first axial portion m, the cross-sectional area of the second axial portion preferably changes continuously in the transition region,

the preform body is received in a die, wherein the die has the final outer shape of the hollow body to be produced,

a mandrel is introduced into the preform body, wherein the mandrel has the inner shape of the hollow body to be produced, and

by an axial movement of the mandrel of the Vorformkorper is die-formed in the die in the final shape of the hollow body.

2. The method according to claim 1, wherein the preform body is produced from at least one printed circuit board using the rolling-in technique or by a U-O-forming.

3. The method of claim 1 or 2, wherein the length of the transition region of the preform body is selected depending on the wall thickness of the formed board, the shape change in the shape transition, and depending on the material.

4. Method according to one of claims 1 to 3, characterized in that the preform body has at least one axial section the outer and inner shape of the hollow body to be produced.

5. The method according to any one of claims 1 to 4, d a d u r c h e c e n e z e c h e n e, d a s s functional elements and / or secondary molding elements are introduced into the hollow body to be produced.

6. The method according to any one of claims 1 to 5, characterized in that for the production of Vorformkorpers boards made of steel, a steel alloy, in particular made of high-strength steel are used.

7. Method according to one of claims 1 to 6, characterized in that the preform body is produced from tailored blanks.

8. An apparatus for producing a hollow body (1) made of metal, which at least a first axial section

(2) with a first cross-sectional area and a second axial section (3) with a second cross-sectional area and in which both axial sections (2, 3) adjoin one another in the axial direction of the hollow body via a shape transition (8) running in a radial plane, in particular for the passage of a Method according to one of claims 1 to 7, characterized in that a first die (10) for producing a Vorformkorpers (1) is provided from a board using the Einrolltechnik or the U-0 Uitιformenverfahrens, wherein the first die (10) so in that the preform body (1) has at least one transition region (4) extending between the first and second axial sections (2, 3) in the axial direction of the hollow body to be produced and in the transition region (4) the cross-sectional area of the preform body (1 ) from the cross-sectional area of the first axial section (2) in the cross-sectional area of the second Axial section (3) preferably continuously changes, and at least one second die (5) for receiving the produced Vorformkorpers (1) is provided with a forming mandrel (7), wherein the second Die (5) has the outer end shape of the hollow body, the mandrel (7) has the inner end shape of the hollow body to be produced and the forming mandrel (7) relative to the second die (5) is axially displaceable.

9. Device according to claim 8, characterized in that the first and / or the second die (10, 5) and / or the forming mandrel (7) has means for introducing functional and / or secondary shaped elements into the hollow body.

10. The device according to claim 8 or 9, characterized in that means for automatically transporting a board in the first die (10) of the device (9) and / or means for inserting the preform body in the second die and / or means for removal of the hollow body are provided from the second die.

11. hollow body made of metal, which has at least a first axial section (2) with a first cross-sectional area and a second axial section (3) with a second cross-sectional area and wherein both axial sections (2, 3) of the hollow body via a running in a radial plane shape transition ( 8) are connected to each other, produced by a method according to claim 1 to I _1, in particular using a device according to claim 9 to 10, wherein the maximum sheet thickness change in the axial direction of the hollow body, in particular in the region of the mold transition is +/- 15%.

12. A hollow body according to claim 11, wherein the hollow body is made of steel, a steel alloy and / or high-strength steels.