## HYDRO-PNEUMATIC VICE WITH PRESSURE BOOSTER

SYNOPSIS
This project deals with the design and fabrication of the hydro pneumatic vice with an air-to-hydraulic pressure booster, the hydro pneumatic vice is capable of holding small and minute work pieces with a large force thus enabling accurate and precise operation. The project combines the advantages of both hydraulics and pneumatics, thus eliminating the drawbacks that may be associated with the use of fluid power Also the air-to-hydraulic pressure booster amplifiers the force with which the vice grips the workpiece. The highlights of this project are that it is very economical, accurate, and easy to operate and has wide variety of applications.
INTRODUCTION
This project deals with the operations of a machine vice using fluid power. Fluid power enables us to operate the vice with ease, accuracy, safety and for high pressure operations. The advantages of hydraulics and pneumatics are merged in such a manner in this project so as to completely eliminate any disadvantage that may be associated with the use of fluid power. The presence of an air-to-hydraulic pressure boaster in this hydro pneumatic vice enables multiplication of force. A small pneumatic pressure is utilized to generate a high hydraulic fluid pressure which bears on a hydraulic actuator. Also the use of standard components and materials has lead to the considerable reduction in
fabrication cost.
AIR-TO-HYDRAULIC PRESSURE BOOSTER
The air – to – hydraulic pressure booster works on the basis of PASCALS’S LAW.
Pascal’s Law:
The pressure applied to a confined fluid is transmitted undiminished in all directions. Let us assume that a 10 square inch air piston is subjected to 100 psi air pressure. This pressure produces 1000 lb force on the hydraulic cylinder piston. Thus if the area of the hydraulic piston is 1 square inch, the hydraulic discharge oil pressure will be 1000 psi. Thus the pressure with which the vice clamps the workpiece is very high.

The pressure ratio of an air-to-hydraulic pressure booster can be found by using

Pressure Ratio = (Output Oil pressure / Input Air Pressure)
Hence a large diameter air cylinder drives a small diameter hydraulic cylinder.
Thus expensive pumps and high pressure valves of the conventional hydraul ic system are eliminated.
WORKING PRINCIPLE
Holding the work pieces:
Air from a single stage air compressor enters the push button direction control valve and is directed to the pneumatic actuator. The pneumatic actuator is a single acting cylinder and the compressed air extends the piston. The piston rod enters the hydraulic Tank filled with hydraulic oil and pressurises the hydraulic fluid. Thus the hydraulic fluid enters the delivery pipe through a filter arrangement. The pressurised fluid is made to act on a hydraulic cylinder placed on a table arrangement. The hydraulic fluid then extends the hydraulic piston. The end of the piston rod is threaded and the movable jaw of the machine vice is connected to it. Thus the movable jaw extends along with the piston rod and grips the workpiece against the fixed jaw placed diametrically opposite to it.
Releasing the work piece:
The operation of hand lever activates the spring centered two ways, two positions, direction control valve in the hydraulic circuit. Also, the push button direction control valve in the pneumatic circuit is operated simultaneously. This exhausts the air in the pneumatic cylinder, thus retracting the pneumatic piston. At the same time, hydraulic fluid flows back to the hydraulic tank. Hence the single acting hydraulic cylinder retracts the hydraulic piston thereby releasing the workpiece.
APPLICATIONS
1. To hold the job rigidly while machining.
2. For quick clamping and unclamping of the job.