Tube bending apparatus
US4970885A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 12, 1989 |
| Grant date | Nov 20, 1990 |
| Priority date | — |
| Expiry date | Jun 12, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21D7/12
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
An electrohydraulic system for bending tube stock includes a bend head having a mandrel and an actuator coupled to a bending die for engaging the tube stock and bending the stock around the mandrel. A clamp is coupled to a second actuator for gripping the tube stock, and a third actuator mechanism in the form of a boost cylinder is coupled to the clamp for urging the tube stock lengthwise into the bend head. An electrohydraulic valve is responsive to an electronic valve control signal for variably feeding hydraulic fluid to the boost cylinder, and velocity of slip at the clamp is determined. An input pressure command signal is compared with pressure at the boost cylinder to develop a pressure error signal. Slip velocity is compared with a velocity limit command to develop a velocity difference when slip velocity exceeds the velocity limit, and the pressure error signal is modulated and employed as the valve command signal to maintain slip velocity at or below the level of the velocity limit command.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.