Method for Internal High-Pressure Deformation of a Blank

Abstract

The invention relates to an apparatus for the hydroforming of a blank with the aid of a high-pressure fluid, having a die which has a receiving space for a blank, wherein the die has at least one passage which opens out in the receiving space and through which residual fluid located in the receiving space can be transported out of the receiving space. The invention also relates to methods for operating an apparatus for the hydroforming of a blank.

Description

BACKGROUND AND SUMMARY OF THE INVENTION [0001] This invention relates to a method for operating an apparatus for hydroforming a blank. [0002] Hydroforming is becoming increasingly important in the automotive industry in order to allow the production of body components. First of all, undeformed blanks, for example tubes, are inserted into the receiving space of a die. The geometry of a receiving space corresponds to the desired external geometry of the finished component. The blank is acted on by high-pressure fluid so that the walls of the blank are plastically deformed and come to bear against the walls of the receiving space. It is in this way possible to economically produce high-strength, complex components. [0003] To assist the deformation process and to minimize friction which occurs between the wall of the receiving space and the outer skin of the blank, it is known from European document EP 0 771 598 A1 to supply the receiving space with lubricant. The lubricant has the effe...

AI Technical Summary

Benefits of technology

[0002] Hydroforming is becoming increasingly important in the automotive industry in order to allow the production of body components. First of all, undeformed blanks, for example tubes, are inserted into the receiving space of a die. The geometry of a receiving space corresponds to the desired external geometry of the finished component. The blank is acted on by high-pressure fluid so that the walls of the blank are plastically deformed and come to bear against the walls of the receiving space. It is in this way possible to economically produce high-strength, complex components.

[0003] To assist the deformation process and to minimize friction which occurs between the wall of the receiving space and the outer skin of the blank, it is known from European document EP 0 771 598 A1 to supply the receiving space with lubricant. The lubricant has the effect of allowing the outer skin of the blank to slide along the wall of the receiving space. It is in this way possible to avoid undesirable distortion.

[0009] Working on this basis, the object of the present invention is to improve a method of the type referred to above in such a manner that a reproducibly good process quality is ensured.

[0013] In the abovementioned methods, it may be advantageous to use a low-viscosity lubricant, since, compared to high-viscosity lubricants, a low-viscosity lubricant is easier to remove from the receiving space of a die.

[0014] As has already been explained above, the residual fluid substantially comprises high-pressure fluid but may also include dirt particles, lubricant residues and / or inclusions of air. The at least one passage ensures that the receiving space can be drained or vented before a deformation process begins, so that a subsequent deformation process is not affected or disrupted by the presence of residual fluid in the receiving space.

[0018] It is particularly advantageous if the passage through which residual fluid located in the receiving space can be removed from the receiving space is also suitable for supplying and / or removing lubricant. This allows the die to be of particularly simple configuration, since only at least one passage need be present compared to the use of separate passages and lines.

Problems solved by technology

One problem with the hydroforming apparatuses which are known from the prior art is that, following the actual deformation operation, residual fluid collects in the receiving space.

After the blank has been removed from the die, the residual fluid remains in the receiving space and may have an adverse effect on a subsequent deformation process.

On the one hand, the residual fluid enclosed in the receiving space is substantially not compressible, with the ensuing risk that a blank that is to be deformed cannot adopt the geometry predetermined by the wall of the receiving space during the deformation process and remains undeformed in a region in which residual fluid is present in the receiving space.

A second problem is that a reliable supply of lubricant is not ensured in those regions of the receiving space in which the residual fluid has collected.

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