Claims
- 1. A die assembly for draw stamping sheet metal in a press comprising:
- an upper die structure and a lower die structure, each constructed and arranged to be mounted on a press for reciprocal movement therebetween, said upper die structure and said lower die structure having complementary stamping surfaces for stamping sheet metal to a desired configuration,
- a clamping assembly and a stretching assembly constructed and arranged to both a) grip said sheet metal along opposite sides of said complementary stamping surfaces and b) drivingly move apart in response to force generated by said upper die structure moving towards said lower die structure, pre-stretching said sheet metal as said upper die structure and said lower die structure are closed to stamp the sheet metal to said desired configuration.
- 2. A die assembly for draw stamping sheet metal in a press comprising:
- an upper die structure and a lower die structure, each constructed and arranged to be mounted on a press for reciprocal movement therebetween, said upper die structure and said lower die structure having complementary stamping surfaces for stamping sheet metal to a desired configuration,
- a clamping assembly and a stretching assembly constructed and arranged to grip said sheet metal along opposite sides of said complementary stamping surfaces and to drivingly move apart in response to movement of said upper and lower die structures towards one another, pre-stretching said sheet metal as said upper die structure and said lower die structure are closed to stamp the sheet metal to said desired configuration,
- wherein said clamping assembly includes
- an upper clamping surface on said upper die structure and a lower clamping surface on said lower die structure and said stretching assembly includes an upper clamp structure on said upper die assembly and a lower clamp structure on said lower die structure, said upper clamp structure and said lower clamp structure being mounted for movement towards and away from said upper and lower clamping surfaces, and
- force imparting structure mounted within said die assembly and constructed and arranged to impart force to move said upper and lower clamp structures away from said upper and lower clamping surfaces after said one end portion of said sheet metal is clamped between said upper and lower clamping surfaces and said opposite end portion of said sheet metal is clamped between said upper clamp structure and said lower clamp structure, thus causing said sheet metal to be stretched as the upper and lower die structures move towards one another.
- 3. A die assembly according to claim 2, wherein said force imparting structure comprises a first camming structure comprising a camming surface which cams said upper clamp structure in a direction away from said upper and lower clamping surfaces.
- 4. A die assembly according to claim 3, wherein said force imparting structure comprises a second camming structure comprising a camming surface which cams said lower clamp structure in a direction away from said upper and lower clamping surfaces.
- 5. A die assembly according to claim 4, wherein said first camming structure is fixed to said upper die structure.
- 6. A die assembly according to claim 5, wherein said second camming structure is fixed to said lower die structure.
- 7. A die assembly according to claim 4, wherein said upper clamp structure comprises a camming surface constructed and arranged to engage the camming surface of said first camming structure, and wherein the force of said press ram causes said camming surface of said first camming structure to cam said camming surface of said upper clamp structure after said upper clamp structure and said lower clamp structure clamp said opposite end of said sheet metal therebetween, so as to move said upper and lower clamp structure in said direction away from said upper and lower clamping surfaces.
- 8. A die assembly according to claim 7, wherein said force imparting structure further comprises a second camming structure fixed to said upper die structure,
- said second camming structure fixed to said upper die structure being moved into forced engagement with a camming structure fixed to said lower clamp structure so as to drive said lower clamp structure in said direction away from said upper and lower clamping surfaces.
- 9. A die assembly according to claim 2, wherein said upper clamp structure is mounted to said upper die structure in a manner permitting relative vertical movement thereof with respect to said upper stamping surface, wherein said upper stretching assembly further comprises a biasing device connected with said upper clamp structure and constructed and arranged to yieldingly resist said relative vertical movement of said upper clamp structure when said opposite end portion of said sheet metal is engaged by said upper clamp structure and said lower clamp structure to facilitate clamping of said opposite end portion of said sheet metal between said upper clamp structure and said lower clamp structure.
- 10. A die assembly according to claim 2, wherein said lower stretching assembly comprises a vertically movable structure mounted for vertical movement with respect to said lower stamping surface, said lower clamp structure being mounted on said vertically movable structure for vertical movement therewith,
- said upper stretching assembly comprises a vertically movable mounting structure mounting said upper clamp structure for vertical movement with respect to said upper stamping surface,
- said upper clamping surface being mounted for vertical movement with respect to said upper stamping surface,
- said lower clamping surface being mounted for vertical movement with respect to said lower stamping surface,
- said upper clamping surface and said lower clamping surface being movable together in a vertical direction with said one end portion of said sheet metal clamped therebetween, and said upper clamp structure and lower clamp structure being movable together in a vertical direction with said opposite end portion of said sheet metal clamped therebetween so as to stretch said sheet metal over said lower stamping surface prior to said upper stamping surface engaging said upper surface of the stretched sheet metal.
- 11. A die assembly according to claim 10, wherein said upper and lower clamp structures move away from said upper and lower clamping surfaces simultaneously with said upper and lower clamp structures moving vertically with respect to said upper and lower clamping surfaces, respectively.
- 12. A die assembly according to claim 11, wherein portions of said sheet metal between said one end portion clamped between said upper and lower clamping surfaces and said opposite end portion clamped between said upper and lower clamp structures are suspended in spaced, overlying relation with respect to said lower stamping surface when said one end portion and said opposite end portion of said sheet metal are initially clamped, and wherein said upper clamp structure and said lower clamp structure are moved away from said upper and lower clamping surfaces by said force imparting structure to stretch said sheet metal prior to said sheet metal engaging said lower stamping surface.
- 13. A die assembly according to claim 10, wherein a length of said sheet metal between said one end and said opposite end is stretched at least 3% relative to its initial length by movement of said upper clamp structure and lower clamp structure away from said upper clamping surface and lower clamping surface.
- 14. A die assembly according to claim 13, wherein said stretching of at least 3% is accomplished prior to vertical movement of said upper and lower clamping surfaces and said upper and lower clamp structures, so that said stretching of at least 3% is accomplished prior to stretching said sheet metal over said lower stamping surface.
- 15. A die assembly according to claim 14, wherein said length of said sheet metal is stretched less than 6% prior to said stretching said sheet metal over said lower stamping surface.
- 16. A die assembly according to claim 10, wherein movement of said upper and lower clamp structures away from said upper and lower clamping surfaces stretches a length of said sheet metal between said one end and said opposite end thereof by at least 3% relative to its initial length.
- 17. A die assembly according to claim 10, wherein movement of said upper and lower clamp structures away from said upper and lower clamping surfaces stretches a length of said sheet metal between said one end and said opposite end thereof by at least 3% relative to its initial length, and wherein vertical movement of said upper and lower clamping structures and said upper and lower clamping structures and said upper and lower clamping surfaces for stretching said sheet metal over said lower stamping surface effects stretching of said sheet metal additional to said at least 3%.
- 18. A die assembly according to claim 10, wherein said vertically movable mounting structure comprises a binder structure mounted for vertical movement by a plurality of nitrogen cylinders.
- 19. A die assembly according to claim 10, wherein said upper and lower clamping surfaces are provided on binder structures mounted for vertical movement by nitrogen cylinders.
- 20. A method for draw stamping sheet metal in a draw stamping die assembly mounted in a press, said method comprising:
- clamping one end portion of sheet metal with a first clamping assembly of said die assembly;
- clamping an opposite end portion of said sheet metal with a second clamping assembly of said die assembly;
- using force provided by said press to move said first clamping assembly away from said second clamping assembly to stretch said sheet metal therebetween; and
- stamping said sheet metal between die surfaces of said die assembly after said sheet metal has been stretched as aforesaid,
- wherein said clamping of the one end portion of said sheet metal and said clamping of the opposite end portion of said sheet metal are performed using said force provided by the press.
- 21. A method according to claim 20, wherein said first clamping assembly and said second clamping assembly are movable vertically with respect to a lower die surface of said die surfaces, said method further comprising:
- moving said first clamping assembly and said second clamping assembly downwardly with respect to said lower die surface so as to stretch the sheet metal over said lower die surface after said sheet metal is stretched by said first clamping assembly moving away from said second clamping assembly and before said stamping of said sheet metal between the die surfaces.
- 22. A method for draw stamping sheet metal in a draw stamping die mounted in a press, said method comprising:
- clamping one end portion of sheet metal with a first clamping assembly, said first clamping assembly having a cam surface;
- clamping an opposite end portion of said sheet metal with a second clamping assembly;
- using force provided by said press to move a camming structure of said stamping die into forcible engagement with said cam surface of said first clamping assembly so as to move said first clamping assembly away from said second clamping assembly so as to stretch said sheet metal therebetween in an initial stretching operation;
- moving said first clamping assembly and said second clamping assembly together and relative to a first stamping die surface to stretch said sheet metal over said first stamping die surface to stretch said sheet metal in a further stretching operation subsequent to said initial stretching operation; and
- moving a second stamping die surface into engagement with said sheet metal to form said sheet metal between said first and second die surfaces after said sheet metal has been stretched in said initial stretching operation and said further stretching operation,
- wherein said clamping of the one end portion of said sheet metal and said clamping of the opposite end portion of said sheet metal are performed using said force provided by the press.
- 23. A die assembly for draw stamping sheet metal in a press comprising:
- an upper die structure constructed and arranged to be mounted on a press ram for movement between raised and lowered positions, said upper die structure including an upper stamping surface constructed and arranged to engage an upper surface of said sheet metal during a stamping operation, said upper die structure further including an upper clamping surface and an upper stretching assembly on opposite sides of said upper stamping surface, said upper stretching assembly including an upper clamping structure which is movable with respect to said upper clamping surface;
- a lower die structure including a lower stamping surface constructed and arranged to engage a lower surface of said sheet metal opposite said upper surface during said draw stamping operation, said lower die structure further including a lower clamping surface and a lower stretching assembly on opposite sides of said lower stamping surface, said lower stretching assembly including a lower clamp structure which is movable with respect to said lower clamping surface,
- said upper die structure being movable by said press ram from said raised position towards said lowered position so that one end portion of said sheet metal is clamped between said upper and lower clamping surfaces, and so that an opposite end portion of said sheet metal opposite said one end portion is clamped between said upper clamp structure and said lower clamp structure,
- said upper clamp structure and said lower clamp structure being mounted for movement towards and away from said upper and lower clamping surfaces,
- force imparting structure mounted within said die assembly and constructed and arranged to impart force applied by said press ram to said upper and lower clamp structures so as to move said upper and lower clamp structures away from said upper and lower clamping surfaces after said one end portion of said sheet metal is clamped between said upper and lower clamping surfaces and said opposite end portion of said sheet metal is clamped between said upper clamp structure and said lower clamp structure, thus causing said sheet metal to be stretched by the force applied by said press ram;
- said upper stamping surface being movable towards said lower stamping surface by said press ram to engage said stretched sheet metal therebetween and thereby provide said sheet metal with a desired configuration.
- 24. A die assembly according to claim 23, wherein said force imparting structure comprises a first camming structure comprising a camming surface which cams said upper clamp structure in a direction away from said upper and lower clamping surfaces.
- 25. A die assembly according to claim 24, wherein said force imparting structure comprises a second camming structure comprising a camming surface which cams said lower clamp structure in a direction away from said upper and lower clamping surfaces.
- 26. A die assembly according to claim 24, wherein said first camming structure is fixed to said upper die structure.
- 27. A die assembly according to claim 25, wherein said second camming structure is fixed to said lower die structure.
- 28. A die assembly according to claim 26, wherein said upper clamp structure comprises a camming surface constructed and arranged to engage the camming surface of said first camming structure, and wherein the force of said press ram causes said camming surface of said first camming structure to cam said camming surface of said upper clamp structure after said upper clamp structure and said lower clamp structure clamp said opposite end of said sheet metal therebetween, so as to move said upper and lower clamp structure in said direction away from said upper and lower clamping surfaces.
- 29. A die assembly according to claim 23, wherein said upper clamp structure is mounted to said upper die structure in a manner permitting relative vertical movement thereof with respect to said upper stamping surface, wherein said upper stretching assembly further comprises a biasing device connected with said upper clamp structure and constructed and arranged to yieldingly resist said relative vertical movement of said upper clamp structure when said opposite end portion of said sheet metal is engaged by said upper clamp structure and said lower clamp structure to facilitate clamping of said opposite end portion of said sheet metal between said upper clamp structure and said lower clamp structure.
- 30. A die assembly according to claim 28, wherein said force imparting structure further comprises a second camming structure fixed to said upper die structure,
- said second camming structure fixed to said upper die structure being moved into forced engagement with a camming structure fixed to said lower clamp structure so as to drive said lower clamp structure in said direction away from said upper and lower clamping surfaces.
- 31. A die assembly according to claim 23, wherein said lower stretching assembly comprises a vertically movable structure mounted for vertical movement with respect to said lower stamping surface, said lower clamp structure being mounted on said vertically movable structure for vertical movement therewith,
- said upper stretching assembly comprises a vertically movable mounting structure mounting said upper clamp structure for vertical movement with respect to said upper stamping surface,
- said upper clamping surface being mounted for vertical movement with respect to said upper stamping surface,
- said lower clamping surface being mounted for vertical movement with respect to said lower stamping surface,
- said upper clamping surface and said lower clamping surface being movable together in a vertical direction with said one end portion of said sheet metal clamped therebetween, and said upper clamp structure and lower clamp structure being movable together in a vertical direction with said opposite end portion of said sheet metal clamped therebetween so as to stretch said sheet metal over said lower stamping surface prior to said upper stamping surface engaging said upper surface of the stretched sheet metal.
- 32. A die assembly according to claim 31, wherein said upper and lower clamp structures move away from said upper and lower clamping surfaces simultaneously with said upper and lower clamp structures moving vertically with respect to said upper and lower clamping surfaces, respectively.
- 33. A die assembly according to claim 23, wherein portions of said sheet metal between said one end portion clamped between said upper and lower clamping surfaces and said opposite end portion clamped between said upper and lower clamp structures are suspended in spaced, overlying relation with respect to said lower stamping surface when said one end portion and said opposite end portion of said sheet metal are initially clamped, and wherein said upper clamp structure and said lower clamp structure are moved away from said upper and lower clamping surfaces by said force imparting structure to stretch said sheet metal prior to said sheet metal engaging said lower stamping surface.
- 34. A die assembly according to claim 31, wherein a length of said sheet metal between said one end and said opposite end is stretched at least 3% relative to its initial length by movement of said upper clamp structure and lower clamp structure away from said upper clamping surface and lower clamping surface.
- 35. A die assembly according to claim 34, wherein said stretching of at least 3% is accomplished prior to vertical movement of said upper and lower clamping surfaces and said upper and lower clamp structures, so that said stretching of at least 3% is accomplished prior to stretching said sheet metal over said lower stamping surface.
- 36. A die assembly according to claim 35, wherein said length of said sheet metal is stretched less than 6% prior to said stretching said sheet metal over said lower stamping surface.
- 37. A die assembly according to claim 23, wherein movement of said upper and lower clamp structures away from said upper and lower clamping surfaces stretches a length of said sheet metal between said one end and said opposite end thereof by at least 3% relative to its initial length.
- 38. A die assembly according to claim 31, wherein movement of said upper and lower clamp structures away from said upper and lower clamping surfaces stretches a length of said sheet metal between said one end and said opposite end thereof by at least 3% relative to its initial length, and wherein vertical movement of said upper and lower clamping structures and said upper and lower clamping structures and said upper and lower clamping surfaces for stretching said sheet metal over said lower stamping surface effects stretching of said sheet metal additional to said at least 3%.
- 39. A die assembly according to claim 31, wherein said vertically movable mounting structure comprises a binder structure mounted for vertical movement by a plurality of nitrogen cylinders.
- 40. A die assembly according to claim 31, wherein said upper and lower clamping surfaces are provided on binder structures mounted for vertical movement by nitrogen cylinders.
- 41. A die assembly for draw stamping sheet metal in a press comprising:
- an upper die structure constructed and arranged to be mounted on a press ram for movement between raised and lowered positions, said upper die structure including an upper stamping surface constructed and arranged to engage an upper surface of said sheet metal during a stamping operation, said upper die structure further including an upper clamping surface and an upper stretching assembly on opposite sides of said upper stamping surface, said upper stretching assembly including an upper clamping structure which is movable with respect to said upper clamping surface;
- a lower die structure including a lower stamping surface constructed and arranged to engage a lower surface of said sheet metal opposite said upper surface during said draw stamping operation, said lower die structure further including a lower clamping surface and a lower stretching assembly on opposite sides of said lower stamping surface, said lower stretching assembly including a lower clamp structure which is movable with respect to said lower clamping surface,
- said upper die structure being movable by said press ram from said raised position towards said lowered position so that one end portion of said sheet metal is clamped between said upper and lower clamping surfaces, and so that an opposite end portion of said sheet metal opposite said one end portion is clamped between said upper clamp structure and said lower clamp structure,
- said upper clamp structure and said lower clamp structure being mounted for movement towards and away from said upper and lower clamping surfaces,
- force imparting structure mounted within said die assembly and constructed and arranged to impart force applied by said press ram to said upper and lower clamp structures so as to move said upper and lower clamp structures away from said upper and lower clamping surfaces after said one end portion of said sheet metal is clamped between said upper and lower clamping surfaces and said opposite end portion of said sheet metal is clamped between said upper clamp structure and said lower clamp structure, thus causing said sheet metal to be stretched by the force applied by said press ram;
- said upper stamping surface being movable towards said lower stamping surface by said press ram to engage said stretched sheet metal therebetween and thereby provide said sheet metal with a desired configuration.
Parent Case Info
This application claims the benefit of U.S. Provisional Application No. 60/059,294, filed Sep. 18, 1997, which is hereby incorporated by reference.
US Referenced Citations (12)
Non-Patent Literature Citations (1)
Entry |
International Search Report re: PCT/CA98/00860 dated Feb. 15, 1999. |