Redrawing method
US4962659A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1989 |
| Grant date | Oct 16, 1990 |
| Priority date | — |
| Expiry date | Feb 23, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21D22/28
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
The present invention provides a redrawing method which comprises holding a preliminarily drawn cup of a covered metal sheet by an annular holding member inserted in the cup and a redrawing die, and relatively moving the redrawing die and a redrawing punch arranged coaxially with the holding member and redrawing cup, the drawing punch being capable of going into the holding member and coming out from the holding member, so that the redrawing die and redrawing punch are engaged with each other, to form a deep-drawn cup having a diameter smaller than that of the preliminarily drawn cup. This redrawing method is prominently characterized in that the radius of curvature of the operating corner portion of the redrawing die is 1 to 2.9 times as large as the bare sheet thickness of the metal sheet. According to this redrawing method, the thickness is effectively reduced by bending anad elongating of the side wall, and the variation of the thickness between the upper and lower portions of the side wall is eliminated and the thickness is uniformly reduced as a whole.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.