Work holding is the most essential act to carry out machining. These are commonly used in the machine shop.
- To hold the job in proper position
- To hold the job rigidly
- To prevent vibration of the job while the machining is carried out.
There are many types of work holding devices like machine vices swivel vices, universal vice, pipe vice, T-Bolt’s ‘U’ clamps, Goose neck clamp, angle plate, Jigs and fixtures etc. These are all mechanical type work holding devices. In this project we are dealing about the pneumatic plain vice used in drilling machine. Here the loading and unloading is quick. The job can be held more rigidly.
A regulator and a pressure gauge is fitted at the entry of the air from the compressor. This is regulated to the required working pressure.
WORK PIECE CLAMPING POSITION:
When the hand lever in the valve is in the ON position, the air from the compressor enters into the main inlet of the valve. At this position, the groove in the valve rod connects the main inlet and the right side inlet port in the valve through this air enters into the cylinder. The air under pressure pushes the piston from right hand side to left hand side. This is turn moves the movable jaw of the vice. The movable jaw moves and holds the job in the vice rigidly.
WORK PIECE RELEASING POSITION:
When the hand lever is pushed to the OFF position, the air from the compressor enters into the main inlet of the valve. At this position, the groove on the left side of the valve rod connects the main inlet and the left side inlet port of the valve. The air enters into the cylinder on the left side of the piston.
This in turn pushes the piston from left to right side. The movable jaw moves back to its position. Unclamping At the same time the groove on the right of the valve rod connects the right side inlet port and the right side exhaust port of the valve, so the air in the right side of the piston escapes to the atmosphere through this passage. The hand lever is operated for tightening and loosening of the job. This allows air to enter into one side of the cylinder and allows the air to escape from the other side of the cylinder to the atmosphere at the same time.
- Idle time of the machine is reduced.
- When compared with the mechanical vices, it consumes less time for clamping and unclamping the job.
- It reduces the manual labour
- Hence, production rate is higher
- In this mechanism there is no backlash.
- Initial higher cost.
- May be a choice of air leakage
- Cylinder stroke length is constant
To hold the job rigidly while machining For quick clamping and unclamping of the job.