Low impact spot welding cylinder using dual pistons
AssigneeDoben Limited
InventorPeter Tenzer
Life of this patent
Estimating the term…
Abstract
A weld cylinder having a dual piston arrangement is provided. The cylinder has a movable retract piston assembly with the piston arranged within the retract piston assembly. The piston supports a rod that is movable between home, intermediate, work, and advanced work positions. The rod moves rapidly from the home position to the intermediate position however, the rod moves more slowly from the intermediate position to the work position to reduce the impact force. A cushion chamber slowly exhausts through a hole in the cushion valve while an isolator is in an open position. Once the cushion valve opens in response to a weld-forward pressure on the cushion valve, the cushion chamber exhausts rapidly so that weld force increases rapidly to minimize increases in cycle time.
Claims15
A weld cylinder comprising:
- a cylinder supporting a rod providing home, intermediate and work positions, the cylinder including a block;
- a retract piston assembly arranged in the cylinder and movable between retract-return and retract-forward positions, the retract piston assembly providing a cushion chamber, the retract piston assembly near the block in the retract-forward position;
- a weld flange arranged in the retract piston assembly and movable between weld-return and weld-forward positions, the weld flange supporting the rod;
- a differential pressure valve regulating pressure in the chamber;
- and
- an isolator cooperating with the differential pressure valve to bias the differential pressure valve to a closed position, the isolator cooperating with the block in the retract-forward position to move the isolator from a closed position to an open position.
A method of welding by moving from a retracted weld position to an extended weld position, the method comprising the steps of:
- a) filling a cushion chamber that opposes movement from the retracted weld position to the extended weld position;
- b) opening an isolator while a differential pressure valve is in the closed position to create an opening between the differential pressure valve and the isolator to exhaust fluid from the cushion chamber;
- and
- c) opening the differential pressure valve to more rapidly exhaust the fluid from the cushion chamber than in step b).
Dependencies are inferred from the claim text.