POINT FORMING PROCESSES

• US 20110061434A1
• Filed: 09/17/2009
• Published: 03/17/2011
• Est. Priority Date: 09/17/2009
• Status: Active Grant

• Current Assignee: National Machinery, LLC (NM Group Global LLC)
• Original Assignee: National Machinery, LLC (NM Group Global LLC)
• Inventors: Krintzline, Donald E., Hay, Thomas E.
• Granted Patent: US 8,813,533 B2
• Time in Patent Office: Days
• US Class Current: 72/60
• CPC Class Codes: B21C 1/32 Feeding or discharging the material or mandrels
• CPC Class Codes: B21C 25/02 Dies
• CPC Class Codes: B21C 9/00 Cooling, heating or lubricating drawing material B21C3/14 takes precedence
• CPC Class Codes: B21J 3/00 Lubricating during forging or pressing lubricating in general F16N
• CPC Class Codes: B21J 9/022 multi-stage forging presses handling devices B21K27/00

Abstract

A set of tooling for a progressive forming machine comprising die and tool units having internal complementary cavity portions for receiving a workpiece, one of said units being arranged to slide a limited distance along its axis and to be biased by a spring force towards the other unit when the units are mounted in the forming machine, the units each having an end face with a smooth surface finish adapted to press against the smooth surface finish of the end face of the other unit, the end face area of one of the units being relatively small compared to its major cross-sectional area whereby a high contact pressure between the end faces is obtained for a given spring bias force such that extrusion/cooling oil coating a workpiece received in the cavity portions is restrained from leakage from the cavity portions across said end faces during a hydrostatic trapped extrusion of the workpiece in the die and tool units whereby the die and tool units are capable of shaping the workpiece to a degree beyond limits of conventional cold-forming processes.

Claims

1. A set of tooling for a progressive forming machine comprising die and tool units having internal complementary cavity portions for receiving a workpiece, one of said units being arranged to slide a limited distance along its axis and to be biased by a spring force towards the other unit when the units are mounted in the forming machine, the units each having an end face with a smooth surface finish adapted to press against the smooth surface finish of the end face of the other unit, the end face area of one of the units being relatively small compared to its major cross-sectional area whereby a high contact pressure between the end faces is obtained for a given spring bias force such that extrusion/cooling oil coating a workpiece received in the cavity portions is restrained from leakage from the cavity portions across said end faces during a hydrostatic trapped extrusion of the workpiece in the die and tool units whereby the die and tool units are capable of shaping the workpiece to a degree beyond limits of conventional cold-forming processes.

2. A set of tooling for hydrostatically forming a workpiece in a workstation in a multi-station cold-forming machine comprising die and tool units for mounting in workstation receiving areas, respectively, of a die breast and a slide reciprocal towards and away from the die breast, said units having generally cylindrical configurations with respective axes, said units being mountable at a common workstation with their axes coincident, one of said units being mountable in its workstation for movement along its axis and having provisions capable of limiting such movement to a distance substantially shorter than its length, the die and tool units having respective end faces and when mounted in their respective receiving areas are opposite one another and form complementary cavity sections for receiving and/or shaping a workpiece, one end face being substantially smaller in area than in area bounded by its circular profile, both of said end faces each having a smooth surface capable, when held together by a spring associated with said one unit during an advance stroke of the slide and forming of a workpiece in said cavity zones, of sealing against leakage of extrusion/cooling oil carried on the workpiece so that a workpiece is formed in said cavity zones by hydrostatic pressure of said oil.

3. A set of tooling for performing a high reduction in area of a workpiece by hydrostatic trap extrusion at a workstation in a multi-die cold-forming machine including a die unit and a tool unit, the die and tool units each having a cylindrical case and an insert in the case, the die case having a formation permitting limited sliding movement in a die breast, the die insert having an end face and a generally cylindrical bore for receiving a generally cylindrical major portion of a workpiece, the tool insert having an end face and a circular cavity that is reduced in size with distance from its end face, the end faces being adapted to be held in contact during a final part of an advance stroke of the slide by a spring biasing the die unit towards the tool unit, the surfaces of the die and tool inserts being relatively smooth and the contact area being relatively small whereby the contact pressure between these insert end faces produced by spring force is sufficiently high to retain extrusion/cooling oil in the cavity portions formed by said inserts during forming of said workpiece.

4. A method of cold-forming workpieces in a multi-die machine comprising the steps of receiving a workpiece at a workstation, providing a set of tooling including die and tool units respectively supported on a die breast and slide, one of the tooling units being arranged to slide a limited distance on its supporting structure, a spring arranged to bias said one tooling unit towards the other tooling unit, the end faces of the die and tool units being arranged with mutual contact areas that are smooth and limited in size, dispensing extrusion/cooling oil at the workstation in a manner that coats the exterior of the workpiece, the die and tool units being arranged such that their end faces engage before the slide reaches its forwardmost position while the spring maintains a contact force at their end faces, the relationship of the spring force and contact area being such that the end faces seal sufficiently against escape of oil from the cavity formed by the die and tool units whereby forming pressure is imparted to the workpiece to produce a consequent hydrostatic pressure in the oil in the cavity that facilitates a high change in cross-section of the workpiece.

5. A method of cold-forming as set forth in claim 4, wherein the change in cross-section is a high area reduction.

6. A method of cold-forming as set forth in claim 4, wherein the area of reduction is concentric with an axis of the workpiece.

7. A method of cold-forming with high reduction in area comprising operating a cold-forming machine with a die breast and a slide that reciprocates towards and away from the die breast, mounting a die on the die breast for limited sliding movement along a direction parallel to the slide motion, biasing the die with a spring towards the slide whereby the end faces of the die and cooperating tool are held together for a distance in the final portion of the advance stroke of the slide for a trap extrusion, inserting a cylindrical workpiece in the die, before insertion of the workpiece, flooding it with extrusion/cooling oil and maintaining a kickout pin at the entrance to the die to exclude appreciable volume of oil apart from that coating the workpiece, the force of the spring being sufficiently high in relation to the contact area of the die and tool end faces and the finish of these end faces being effective to seal against significant leakage of oil across these faces such that a trapped extrusion of the workpiece into the tool is augmented by a hydrostatic extrusion effect of the oil to achieve a high reduction of area of the workpiece in the tool.

8. A method as set forth in claim 7, in which the workpiece is transferred to a subsequent workstation where it is open-extruded to effect a further reduction in area.

9. A method as set forth in claim 8, wherein the workpiece is transferred to a successive workstation where it is upset and further pointed.

10. A method as set forth in claim 7, wherein the workpiece is transferred to a successive workstation wherein the reduced area end is upset to form a small bulb and is subsequently transferred to a workstation where the bulb is pulled off the workpiece to reduce the cross-sectional area of the resulting end of the workpiece.

11. A method as set forth in claim 10, wherein the workpiece is transferred to a subsequent workstation where it is upset and further pointed.

12. A method as set forth in claim 7, wherein the workpiece is transferred to a subsequent workstation where the reduced area end of the workpiece is upset pinched to further reduce its area and is thereafter transferred to another workstation where the pinched material is trimmed by a shear action.

13. A method as set forth in claim 11, wherein the workpiece is transferred to a subsequent workstation where it is further pointed.

14. A method as set forth in claim 7, wherein the workpiece is transferred to a subsequent workstation where the reduced area end of the workpiece is upset pinched to further reduce its area and is thereafter transferred to another workstation where the pinched material is broached from the workpiece.

15. A method as set forth in claim 14, wherein the workpiece is transferred to a subsequent workstation where it is upset and further pointed.

16. In a multi-station cold-forming machine having a die breast and a slide reciprocal towards and away from the die breast, a plurality of workstations, the die breast carrying dies at respective workstations and the slide carrying tools at respective workstations, the die and tool of at least one workstation being arranged to perform a hydrostatic large change in cross-sectional area of a workpiece such that hydrostatic pressure of liquid lubricant in a workpiece forming space surrounding the workpiece across a plane of separation of the tool and die when the workpiece is fully trapped in said space whereby an area reduction of more than 75% can be obtained on a workpiece, the die and tool of the one workstation having mutually engagable surfaces of limited size and adequate finish such that when engaged, during a forming stroke, provide sufficient contact pressure and sealing to maintain such hydrostatic pressure.

17. In a multi-die cold-forming machine having a die breast and a slide that reciprocates towards and away from the die breast, a plurality of workstations on the die breast and slide, the die breast supporting dies at its workstations and the slide supporting tools at its workstations, the die and tool units of one workstation being arranged to perform a large change in cross-section of a workpiece by consequent hydrostatic forming with hydraulic pressure imposed by extrusion/cooling oil on the workpiece in a cavity formed by the die and tool units, a dispenser for coating the workpiece with extrusion/cooling oil before it is fully recede in the cavity, the die and tool units having opposed end faces, one of the tool and die units being supported for limited sliding movement on its support and being biased by a spring towards the other one of the tool and die units, the tool end face closing on the die end face to trap a workpiece prior to completion of an advance stroke of the slide, the spring allowing said one tooling part to receive in its sliding movement relative to its support while maintaining a high contact force between said end faces, the end faces being arranged such that the area of contact between said end faces is relatively small compared to the profile of either the die or tool units so that the spring is capable of developing sufficient contact pressure between the die and tool end faces under hydrostatic forming pressures developed in the cavity during the final advancing movement of the slide.

18. A multi-die cold-forming machine as set forth in claim 17, wherein the die has a cylindrical cavity portion with a diameter closely fitting with the workpiece and a length several times the diameter, a kickout pin closely fitting the cavity to minimize loss of oil through any clearance.

19. A multi-die cold-forming machine as set forth in claim 18, wherein the die is slidably mounted on the die breast, the spring being arranged to bias the die towards the slide.

20. A multi-die cold-forming machine as set forth in claim 17, wherein the tool has a cavity portion that becomes smaller with distance from its end face and is configured to produce a large reduction in area on the end of the workpiece it contacts.

21. A multi-die cold-forming machine as set forth in claim 20, including two workstations preceding said trap forming workstation, a first station having die and tool elements for squaring the end of the workpiece and the second of said workstations having die and tool elements for forming a small radius at the workpiece end.

22. A multi-die cold-forming machine as set forth in claim 21, including two workstations succeeding said trap forming workstation, a first succeeding workstation having die and tool elements for open extrusion of the workpiece to further reduce the areas of its end and a second succeeding workstation having die and tool elements for upsetting and further reducing the area of the end of the workpiece.

23. In a multi-die cold-forming machine having a die breast and slide that reciprocates in a direction towards and away from the die breast, a plurality of workstations on the die breast and slide, the die breast supporting dies at its workstations and the slide supporting tools at its workstations, the die and tool of one workstation being configured to trap extrude a relatively long workpiece to effect a high reduction in area in the tool by consequent hydrostatic forming with hydraulic pressure imposed by extrusion/cooling oil on the workpiece in a cavity mutually formed by the die and tool, a dispenser for coating the workpiece with extrusion/cooling oil before it is fully received in the cavity, a die kickout pin capable of excluding a detrimental volume of oil from the die prior to entry of the workpiece into the die, the die and tool having opposed end faces, the die being supported on the die breast for limited sliding movement in a direction along the direction of reciprocation of the slide, a spring biasing the die towards the tool, the tool end face closing on the die end face prior to completion of the advance stroke of the slide, the spring allowing the die to recede relative to the die breast while maintaining a high contact force between the end faces, the end faces being highly finished and arranged such that the area of contact between them is relatively small compared to the profile of either of the die or tool so that the spring is capable of developing sufficient contact pressure between the end faces to prevent escape of extrusion/cooling oil across the end faces under hydrostatic forming pressures developed in the cavity during the final advancing movement of the slide.

24. A multi-die cold-forming machine as set forth in claim 23, including two workstations preceding said trap extruding workstation, a first station having die and tool elements for squaring the end of the workpiece and the second of said workstations having die and tool elements for forming a small radius at the workpiece end.

25. A multi-die cold-forming machine as set forth in claim 24, including two workstations succeeding said trap extruding workstation, a first succeeding workstation having die and tool elements for open extrusion of the workpiece to further reduce the areas of its end and a second succeeding workstation having die and tool elements for upsetting and further reducing the area of the end of the workpiece.

26. A multi-die cold-forming machine as set forth in claim 24, including a subsequent workstation having die and tool components for upsetting a bulb on a reduced area end formed on the workpiece at said high area reduction workstation.

27. A multi-die cold-forming machine as set forth in claim 26, including a workstation having tool and die components for pulling said bulb from the remainder of the workpiece to reduce the area of its end.

28. A multi-die cold-forming machine as set forth in claim 24, including a subsequent workstation having tool and die components for pinch pointing the reduced area of the workpiece.

29. A multi-die cold-forming machine as set forth in claim 28, including a subsequent workstation having tool and die components for removing material flash produced in the pinch pointing.

30. A progressive forming machine comprising a die breast and a slide arranged to reciprocate towards and away from the die breast, the die breast and slide each serving as a carrier for complementary opposing tools at respective workstations, one of said workstations having a slidable tool mounted for limited sliding movement relative to its carrier, a force lever operated by a spring biasing said slidable tool towards its opposing tool, said slidable tool and its opposing tool being arranged to simultaneously laterally trap and extrude a workpiece at said one workstation during the forward stroke of the slide.

31. A progressive forming machine as set forth in claim 30, wherein the slidable tool is carried on the die breast to reverse form the workpiece.

32. A progressive forming machine as set forth in claim 30, wherein the opposing tools at said one workstation have mutually contacting surfaces of limited area and the lever and spring are sized relative to said limited area to develop sufficient contact pressure to confine lubricating liquid on said workpiece to produce hydrostatic extrusion of said workpiece.

33. A method of achieving a high reduction of area on a workpiece at a workstation in a progressive forming machine having a die breast and a slide arranged to reciprocate towards and away from the die breast, the die breast and slide each being arranged to serve as a carrier for a mutually complementary opposing tool at respective workstations, at one station mounting one of the tools for limited movement relative to its carrier, biasing said one tool against its opposing tool with a spring through a force multiplying lever so that the workpiece is simultaneously laterally trapped and extruded by the tools at said one workstation during the forward stroke of the slide.

34. A method as set forth in claim 33, wherein the spring biased tool is provided on the die breast to enable the workpiece to be reverse formed.

35. A method as set forth in claim 33, wherein the workpiece is covered with a liquid lubricant and mutual contact areas between the tools at said one workstation are maintained in contact by the spring and lever with sufficient force to sustain hydrostatic pressure in the tools as the workpiece is formed.