Valve mechanism for controlling a pressure difference between an upper and a lower chamber of a hydraulic cylinder for a die cushion for a press
US5140895A · kind A · utility
14Cited by
8References
21Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Oct 3, 1990 |
| Grant date | Aug 25, 1992 |
| Priority date | — |
| Expiry date | Oct 3, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21D24/02
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A double acting hydraulic cylinder is a die cushion for a press, with an upper and a lower chamber in communication with each other and with a differential pressure between the two chambers automatically controlled by a valve mechanism. With the differential pressure controlled according to one of several desired curves, the die cushion capability during press operation can be changed and adjusted to a valve suitable for the product to be processed and so a wide variety of products can be produced in high quality and high efficiency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.