Claims
- 1. Process for manufacturing holes on the circumference of a hollow section situated in an internal high pressure forming tool, by the action of a punch integrated in the forming tool, a desired breaking area being formed on the hollow section which follows the edge contour of an acting face of the punch, and after the withdrawal of the punch, the hollow section material surrounded by the desired breaking area, acted upon by internal high pressure, being extracted from the hollow section from the inside to the outside while forming a hole, wherein,by penetration of the punch into a wall of the hollow section at an internal high pressure, which corresponds to a forming pressure for forming a hollow blank inserted in the forming tool, the wall of the hollow section is weakened by forming an unstable thin area which provides the desired breaking point; and, during withdrawal of the punch the internal high pressure, the hollow section material surrounded by the thin area is torn out of the hollow section in the withdrawal direction of the punch, whereby the hole is generated.
- 2. Process according to claim 1, wherein, for producing a hole of a relatively smaller cross-sectional surface, the wall of the hollow section is weakened more than for producing a hole of a relatively larger cross-sectional surface.
- 3. Process according to claim 1, wherein the hollow section material acted upon by the punch is displaced into a trough on a face of the punch.
- 4. Process according to claim 3, wherein the wall is weakened by stamping the punch into the hollow section wall.
- 5. Process according to claim 3, wherein the wall is weakened by piercing of a punch provided with a ring blade into the hollow section material.
- 6. Process according to claim 1, wherein, before being acted upon by the punch the hollow section is widened by means of internal high pressure into an expansion trough worked into the face of the punch, and hollow section material is displaced from the area of the desired breaking point to be formed into the expansion trough.
- 7. Process according to claim 1, wherein:first by means of the internal high pressure deforming, the hollow section is produced from a hollow blank inserted into the forming tool and is then calibrated; and subsequently the holes are produced in the same forming tool.
- 8. Process according to claim 1, wherein after the abrupt withdrawal of the punch, the hollow section material surrounded by the thin area is torn out of the hollow section wall.
- 9. Process according to claim 1, wherein:the hollow section is expanded by internal high pressure; and the thin area of the hollow section wall is formed in that the expanding hollow section acts upon a punch projecting into the sinking of the forming tool.
- 10. Device for producing holes on the circumference of hollow sections, having an internal high pressure forming tool in whose sinking the hollow section is accommodated for producing the respective hole, and having a punch which is displaceable by driving devices and is accommodated in a guide bore starting out from the sinking of the forming tool, the punch projecting in an operative position with the face directed toward the sinking out of the guide bore and acting upon the hollow section for forming a desired breaking point following an edge contour of the punch, and in an inoperative position, being arranged to be completely withdrawn in the guide bore, wherein:on the face of the punch facing the hollow section, in the edge area, a penetration device is arranged which projects from this face, by means of which penetration device a desired breaking area can be produced which weakens the wall of the hollow section; and by means of a driving device, the punch is supported in the operative position against an internal high pressure corresponding to a forming pressure for forming a hollow blank inserted in the forming tool generated in the hollow section, in this operative position, the penetration depth of the penetration device in the wall of the hollow section being dimensioned such that an unstable thin area is created in the hollow section wall which forms the desired breaking point and which, when the punch is withdrawn, tears on all sides solely by the action of the internal high pressure.
- 11. Device according to claim 10, wherein the penetration device is a ring-shaped wall which has a rectangular cross-section and, by means of its exterior side ends flush with the punch circumference.
- 12. Device according to claim 10, wherein the penetration device is a ring blade whose exterior side is aligned with the punch circumference.
- 13. Device according to claim 10, wherein the punch has a trough on its face which is bounded by the penetration device.
- 14. Device according to claim 10, wherein the driving device is a high-pressure-generating hydraulic system.
- 15. Device according to claim 10, wherein the punch has an axial bore in which a slide is guided by means of which the material which was torn out of the hollow section wall and forms a hole slug, can be pressed out of the guide bore of the punch.
- 16. Device according to claim 15, wherein the face of the slide opposite the hollow section, in its inoperative position, forms a base of an expansion trough in the face of the punch.
- 17. Device according to claim 15, wherein the slide can be displaced until it rests against the hollow section.
Priority Claims (1)
Number |
Date |
Country |
Kind |
196 47 963 |
Nov 1996 |
DE |
|
Parent Case Info
This application is a Divisional application Ser. No. 08/975,170 filed on Nov. 20, 1997 now U.S. Pat. No. 6,484,551.
US Referenced Citations (17)
Foreign Referenced Citations (4)
Number |
Date |
Country |
1 552 122 |
Mar 1971 |
DE |
43 22 063 |
Aug 1994 |
DE |
195 06 067 |
Jun 1996 |
DE |
55-144334 |
Nov 1980 |
JP |