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PROJECT ON DESIGN AND FABRICATION OF CAM VICE

PROJECT ON DESIGN AND FABRICATION OF CAM VICE 

SYNOPSIS

In this project we are fabricate the cam vice. It works in the principle or eccentric cam mechanism. The main features of the cam vice are promotes mass production, can hold irregular jobs, more rigidity, reduce fatigue, etc. Cam was designed to hold the job at high pressure. The other parts were designed to hold the job in rigid condition. Cam vice is suitable for mass production. It is possible to hold irregular components also, and similar components can be very quickly.

INTRODUCTION

Cam vice is one of the clamping devices used to hold the job in rigid condition. Cam vice is operated by eccentric cam mechanism. There is a cam lever. The job can be held tightly in between the jaw. In this, first the job is place in between jaws, and movable jaw is adjusted by adjusting the screw rod to maintain according to the eccentricity of the cam with cam profile. After that, cam lever at the top is operated so that the job is held tightly in the fixture.

PROJECT ON DESIGN AND FABRICATION OF CAM VICE
PROJECT ON DESIGN AND FABRICATION OF CAM VICE 

This type of fixture is useful for mass production where only similar size of jobs is to be held. It reduces operator’s fatigue and also reduces stetting time and cost of production.

DESCRIPTION OF EQUIPMENT

1. CAM

A cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower which is a lever making contact with the cam.
The reason the cam acts as a lever is because the hole is not directly in the centre, therefore moving the cam rather than just spinning. On the other hand, some cams are made with a hole exactly in the centre and their sides act as cams to move the levers touching them to move up and down or to go back and forth.

2. LEAD SCREW
A lead screw also known as a power screw or translation screw, is a screw designed to translate radial motion into linear motion. Common applications are machine slides (such as in machine tools), vises, presses, and jacks.

A lead screw nut and screw mate with rubbing surfaces, and consequently they have a relatively high friction and stiction compared to mechanical parts which mate with rolling surfaces and bearings. Their efficiency is typically between 25 and 70%, with higher pitch screws tending to be more efficient. A higher performing, and more expensive, alternative is the ball screw.

The high internal friction means that leadscrew systems are not usually capable of continuous operation at high speed, as they will overheat. Due to inherently high stiction, the typical screw is self-locking (i.e. when stopped, a linear force on the nut will not apply a torque to the screw) and are often used in applications where backdriving is unacceptable, like holding vertical loads or in hand cranked machine tools.

A lead screw will back drive. A leadscrew's tendency to backdrive depends on its thread helix angle, coefficient of friction of the interface of the components (screw/nut) and the included angle of the thread form. In general, a steel acme thread and bronze nut will back drive when the helix angle of the thread is greater than 20°.

3. FRAME STAND
Frame stand in this device is made up of combination of sheet metal or flat rods welded together. The frame stand is used to hold the fixed jaw, moving jaw, and lever, lead screw, handle and cam arrangements in this device.

4. LEVER 
The lever is used to lock and unlock the cam arrangements in this device. The liver is an easily operateable device in this equipment.

5. HANDLE
The handle is used to adjust operate the lead screw in this equipment. The handle is fixed one corner of the lead screw.

6. FIXED JAW AND MOVING JAW

The fixed jaw is stable; the jaw is mounted on the frame stand in this equipment.

The moving jaw is easily adjustable by the lead screw arrangement. We can easily move the moving jaw on this equipment by rotating the lead screw by handle and operating the lever in cam arrangement.

WORKING PRINCIPLE

The cam vice consists of fixed jaw, moving jaw, lever, lead screw, handle, cam mechanism and frame stand. The fixed jaw is fixed on the frame. The moving jaw is arranged parallel through the fixed jaw. The cam arrangement is placed before the moving jaw. The cam arrangement consists of lever. The after the cam arrangement the lead screw is arranged. The lead screw is used to adjust the cam arrangement in the equipment. The main purpose of the cam vice is used to clamp and unclamp the same size specimens on it. This vice is used in mass production. The specimen is placed between the fixed jaw and moving jaw, and then the cam lever is operated by manually. The specimen is clamped at a perfect stage, and then the lead screw is used to fit the correct area in the cam arrangement. Now we can easily clamp and unclamp the same size of specimens in this equipment very easily.

MERITS
  1. Idle time of the machine is reduced
  2. When compared with the mechanical vices, it continues less time for clamping and unclamping the job
  3. It reduces the clamping time
  4. Hence, production rate is higher
DEMERITS
  1. Limited size of specimens only clamped in this vice
APPLICATIONS
  • Applicable in workshops
  • Applicable in small and medium scale industries
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