Method of forming spring washer blind-holes into a piston for an automobile transmission
US7823432B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | May 13, 2009 |
| Grant date | Nov 2, 2010 |
| Priority date | — |
| Expiry date | May 29, 2029 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21K1/32
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The problem to be solved by the present invention is to clear up an eccentric load onto a pin and a problem of deformation and cavity due to flowing material during extrusion when spring washer blind-holes in a piston for an automobile transmission are formed by extrusion with a pin. After an annular region along the peripheral edge portion on the back of an end plate of a secondary workpiece is flattened, the secondary workpiece is set on a lower die. Further, while the lower die is pressed with upper dies and cushion pressure is applied on the lower die, pins, for piercing the spring washer blind-holes are made to perform an extrusion operation onto the end plate of the secondary workpiece from the backside of the end plate. The extruded material is made to flow into recess holes of the upper die, and thus spring washer blind-holes are formed. Then, projections which have flowed and protrude on the front side are removed by turning with a lathe.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.