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INTRODUCTION
1.1 VICE
A vice is a mechanical screw apparatus used for holding or clamping a work piece to allow work to be performed on it with tool such ass saws, planes, drills, mills, screw drives, jaw which is moved towards or away from jaw by the screw.
1.2 TYPES OF VICE
Without the qualification, "vise" usually refers to a bench with flat, parallel jaws, attached to a workbench. There are two main types.
1. Wood working vice
2. Engineer’s vice
3. Other vices
1.2.1 Wood working vice
For wood working, the jaw is made of wood, plastic, or from metal. This jaw may include a dog hole to hold a bench dog. In the modern metal woodworker's vices, aa split nut is often used. the nut in which the screw turns is in two parts so that by means of a lever, it can be removed from the screw and the movable jaw can be quick slid into a suitable position at which point the nut is again closed to screw so that the vice be closely firmly the work.
2 Engineer’s vice
An Engineer’s vice, also known as a metal working bench vise or flitter’s vise, is used in metal working application. The jaws are made of soft or hard metal. The vise is bolted onto the top surface of the bench. The bench height should be such that the top of the vise jaws is at or just below the elbow height of the user when standing up right.
The vice may include other features such as a small anvil on the back of its body. The nut in which the screw turns may be split so that, by means of a lever, it can be removed from the screw and the screw and movable jaw quickly slide into a suitable position at which point the nut is again closed onto the screw. The disadvantage to this system is lower precision, as compared to a solid screw system.
PLAN OF WORK
Planning is an important task of every project and should be taken with great care as the efficiency of the whole project largely depends upon is planning while planning a project each and every detail should be worked out in anticipation and carefully with all the relating provision in advance. Project planning consists of the following steps.
2.1 SELECTION PROJECT
By considering the benefits of the project with the present condition the amount of money can be invested availability of the material, durability of the project, design and fabrication of the project, the project can be planned.
in this project, the manually operated vice is replaced by pneumatic vice. Movement of jaw by the screw thread will be replaced by reciprocating action of the piston inside the cylinder which is attached to the jaw. It reduces manual effort. This made us to sketch worthy project.
2.2 DESIGN AND DRAWING
Before starting the manufacturing of project, it must be designed. The work of the design should be done very carefully by considering all relevant factors. After designing the project its detailed drawing are prepared so that no doubts are left for future, detailed specification of raw materials and finished product should be decided very carefully along with the specification of machine required for their manufacture.
With the help of AUTO CAD software, design the whole project and express it in form of drawing. The drawing includes the basic structure and the required dimension in it. It gives the guideline to complete the project successfully.
2.3 PURCHASE CONSIDERATION
It is difficult to manufacture all the component needed for the equipment in the workshop itself. Fabrication must be based on the accuracy that can be obtained from the necessary components. If the project need some component, then it is better to buy the component from market and assemble it to the requirement.
2.4 FABRICATION
Fabrication of the components can be done with the help of designed calculation and drawing through different manufacturing process such as cutting, welding, milling, surface hardening etc.,
2.5 ASSEMBLY OF THE PARTS
The fabrication and purchased components are assembled together to complete the fabrication process.
We assembled the components such as base frame, hoses, valve, pneumatic cylinder,, vice arrangement with the help of temporary and permanent joints.
2.6 COST ESTIMATION
The cost of the project can be calculated by considering following
a) Material cost
b) Machining cost
c) Overhead expense
2.7 COMPARISION
The various items in the finished project are compared to the designed diagram and the standards for the further correction
2.8 REPORT
At the end of the project works report ideas prepared for further references. The report consists of all the items which are done the project.
COMPONENTS AND FUNCTION
In this chapter various components are used in the project are explained with their corresponding function.
3.1 Pneumatic cylinder
3.1.1 Single-acting cylinders
3.2 Ball Valves
3.3 Tubes or hoses
3.3.1 Tube fittings
3.4 Air tank
3.5 Vice
3.1 Pneumatic cylinder
Pneumatic cylinder (sometimes known as air cylinders) are mechanical devices which use the power of compressed gas to produce a force in a reciprocating linear motion pneumatics cylinder are quieter, cleaner, and do not require large amounts of space for fluid storage. Pneumatic cylinder operating fluid is a gas, leakage from a pneumatic cylinder will not drip out and contaminate the surroundings, making pneumatics more desirable where cleanliness is a requirement.
Single-acting cylinders
Single-acting cylinders use the pressure imparted by compressed air to create a driving force in one direction (usually out), and a spring to return to the "home" position. More often than not, this type of cylinder has limited extension due to the space the compressed spring takes up. Another downside to Single-acting cylinders is that part of the force produced by the cylinder is lost as it tries to push against the spring. The impeccable tube of Single-acting cylinders is usually made of steel.
3.2 BALL VALVES
A ball valve is a form of turn which uses a hollow, perforated and pivoting ball otherwise called floating ball to control flow through it. It is open when the ball’s hole is in line with the flow and closed when it is open when the ball’s hole is in line with flow and closed when it is pivoted by the valve handle. The handle lies flat in alignment with the flow open and closed. Ball valves are durable performing well after many cycles. The ball valves ease of operation, repair and versatility lend.
3.3 Hoses
Hose is a hollow tubes design to carry fluids from one location to another. Hoses are also sometimes called pipes or more generally tubing. The shape of a hose is usually cylindrical. Hoses are made from one or a combination of many different materials. For e.g. Nylon, Polyurethane and PVC.
3.4 Air tank
Air tank are used for compressed air storage and are recommended to be in all compressed air system.
3.5 Vice
The vice arrangement is used to hold the object with rigidity, it consist of two jaws.
3.5.1 Fixed jaw
3.5.2 Movable jaws
3.5.1 Fixed jaw
The fixed jaw is a single piece which is integral with the base by mean welding. These jaws are used for clamping the work piece with great grip and secure. The other details and specification are given below.
SPECIFICATION
Material - Mild steel
Size - 100×50×10
3.5.2 Movable jaws
A movable clamping jaw (or) moving jaws is a one piece which is fixed to the upper jaw holding column arrangement by means of bolts. These jaws are also serrated used for clamping the work piece with great grip and secure.
The other details and specification are given below.
SPECIFICATION
Material - Mild steel
Size - 100×65×10mm
FABRICATION PROCESS
4.1 WELDING PROCESS
4.1.1 ELECTRODE ARC WELDING
Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metal at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapour or slag. Arc welding may be manual, semi-automatic, or fully automated.
To supply the electrical energy necessary for arc welding processes, a number of different power supplies can be used. The most common classification is constant current power supplies and constant voltage power supplies. In arc welding, the voltage is directly related to the length of the arc, and the current is related to the amount of heat input. Constant current power supplies are most often used for manual welding processes such as gas tungsten arc welding and shielded metal arc welding, because they maintain a relatively constant current even as the voltage varies. This is important because in manual welding, it can be difficult to hold the electrode perfectly steady, and as a result, the arc length and thus voltage tend to fluctuate. Constant voltage power supplies hold the voltage constant and vary the current, and as aresult, are most often used for automated welding processes such as gas metal arc welding, flux cored arc welding, and submerged arc welding. In these processes, arc length is kept constant, since any fluctuation in the distance between the wire and the base material is quickly rectified by a large change in current. For example. If the wire and the base material get too close, the current will rapidly increase, which in turn causes the heat to increase and the tip of the wire to melt, returning it to its original separation distance.
CONSTRUCTION & WORKING
6.1 CONSTRUCTION
The pneumatic vice consists of pneumatic double acting cylinder, base stand, vice arrangement, hose connectors, hoses, manually operated ball valve, compressor.
Initially the outlet port of air compressor is connected to inlet port of manually operated ball valve via hose connector. The valve consist of two ports, each one is connected to the corresponding port of double acting cylinder. The piston on the cylinder is connected to the movable jaw of the vice arrangement by arc welding process.
The vice arrangement contains fixed and movable additions to it contain supporting plate and guide rods with provide support to vice. With the reference to design diagram, cut the GI pipe to make a base stand. In the fabrication of vice the mild steel is used, then the milling and surface grinding is done to make vice.
The double acting cylinder is welded to the base stand, the fixed jaw, supporting plate, guide rod are fixed with the welding process, then the manually operated valve is fixed by nut and bolt. Check whether all the connections are made in right manner.
6.2 WORKING
It works on the principle of PASCAL’S LAW, it states that the pressure applied anywhere to a confined fluid is transmitted equally to every portion of the surface of the containing vessel. When a force is applied to the fluid by a piston, the liquid transmit this force equally to all surface of the container.
Initially starting with air compressor, its function is to compress air from a low inlet pressure (usually atmosphere) to a higher pressure level. This is accomplished by reducing the volume of the air. Air compressor consists of a compressed air tank, electric rotor and pulley drive, pressure control and instrument for quick hook and use. The compressed air from the compressor reaches the ball valve. The ball valve changes the direction of flow according to the requirement.
The compressed air is passed through the ball valve-1 and it is admitted into the rear end of the cylinder block. The air pushes the piston for the work piece clamping. At the end of the stroke air from ball valve occupies the rear end of the cylinder block. This exerts greater pressure on the piston, pushing it at a faster rate thus enabling faster stroke.
The compressed air is passed through the ball valve-2 and it admitted into front end of the cylinder block. The air pushes the piston back. The pressure remains the same but the area is less due to the pressure of the presence of piston rod. At the end of the return stroke air from the ball valve occupies front portion of the cylinder block. So that the work piece or object placed between the jaws is removed, since the jaws were released.
CONCLUSION
This report deals with the design and fabrication of pneumatic vice, and so the design diagram was attached. The fast holding of the objects was achieved by pneumatic system so it increases production on the short time. The pneumatic system can be found in almost all industries and mechanical fields. However some of the industrial applications is punching, clamping, material handling, hammering throughout the project period we gained knowledge on all type of machining process and pneumatic system. We have done our project with ability skill, making maximum use of available facilities.