CHAPTER ONE

DESIGN AND CONSTRUCTION OF 2.5 KG WEIGHT BENCH VICE

INTRODUCTION

A vise (American) or vice (British) is amechanical device used to secure anobject to allow work to be performed onit. Vices have two parallel jaws, one fixedand the other movable, threaded in andout by a screw and lever.

DESCRIPTION OF ABENCH VICE

    A bench vice is like an extra hand. Itspurpose is to hold material steady,allowing you to use both hands to workon the material with other tools.

The bench vise is of the Clamp base Bench design. It is a lightweight, portable vise. It is attached to a table or bench with the mounting clamp. It has rough jaws for holding material with stationary base. Clamp base bench vices are considered most appropriate to hold light materials or in areas where a heavier vice is not available such as laboratories and school workshops.

It consists of a mounting base or body which is secured to the machine table, a stationary jaw against which work piece is located, a movable jaw and screw mechanism consisting of a buttress-threaded spindle and handle. When the spindle is rotated in the clockwise direction using the handle, the jaws move closer thus clamping the workpiece against the stationary jaw. This clamping action holds the part securely while the machining operation takes place. On the other hand, when turned in the anticlockwise direction, the jaws move away thus loosening the grip on the work piece

   The stiffness created through the design that pulled the jaw down has the added benefit of pulling the nut and driving the movable jaw up creating a sandwich of vice body, nut and movable jaw. The resulting stiffness and dampening allowed a significantly lighter vice to be offered, allowing for manual lifting and positioning of the vice on a machine table, which contributed to its popularity.

The stationary jaw is cast integral with the vice body. It is a good selection when density and absolute minimum deflection is needed.

This vise hardware is adaptable for installation in a variety of positions, and on different styles of bench tops.

They areideal for sawing, sanding, plaining,drilling, screwing and soldering.

TYPES OF BENCH VICE

There aretwo types of bench vice that share acommon anatomy.

WOODWORKING VICES

Woodworking vices are usuallyincorporated into the structure of awoodworking bench, often fabricatedfrom the same type of timber as thebench. The top edge of the jaws isusually flush with the bench top anddoes not protrude beyond the edge of thebench.

ENGINEER'S VICE

Engineer's bench vices are also known asmetalworking vices and are typicallyfabricated from iron or steel. These vicesare not an integrated part of theworkbench, allowing them to beremoved and used on any suitable worksurface. They are attached so that thejaws of the vice sit above the level of thework surface, at about elbow height, togive more purpose for working onharder materials and slightly protrudingbeyond the edge of the bench.

COMMON FEATURES

For the engineering bench vise, it consists of two jaws, onestationary and one moveable. These arefitted into a frame with a screwapparatus operated by a lever whichcontrols the moveable jaw, allowing thespace between the jaws to be expandedor contracted to accommodate different-sized pieces of material.

STATEMENT OF PROBLEM

    A problem with known types of vice is that the numerous component parts thereof mean that the clamp is relatively expensive to manufacture. Furthermore, if the clamp is of relatively complex construction it may be similarly complex to operate. In particular, it is inconvenient to have to use both hands in order to clamp an object in the clamp and a one-handed operation would be more desirable. Also, vices tend to be heavy and are normally fixed to a work surface. Research have also shown that the available bench vice are not cost effective, hence these machine tools are not readily available to the engineers, technicians, artisans  who are greatly in need of this machine tool for their daily work in the workshop.

Most vises in the workshops are too big and are not amenable to small work pieces holding. Besides, because of their sizes, their materials of construction are big and hence cost much.

When under pressure, most vise designs deflect creating part alignment problem requiring that lifted work pieces be forced down with hammer

     It is therefore an object of the present invention to provide a clamp which alleviates the above-described problems

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  OBJECTIVES OF THE STUDY

To design a bench vise.

Modify an existing bench vice for small scale workshop production.

To analyze the design structure of the bench vice.

To improve the existing design through material and size reduction

Evaluate the cost of the modified bench vice.

Alleviate the sufferings of engineers, technicians, artisans who use hand to grip object for cutting, planning, gluing etc.

PURPOSE OF THE PROJECT

From the research, it is expected that the student would be exposed to and learn how to progress from design to actual fabrication of equipment, using conventional system.

DESIGN AND OPERATION CONSIDERATIONS

In general, to address the work holding needs of a particular machining operation, one needs to consider part size, material, machine speed, feed rate, and the quantity of Parts to be produced. Single part production or low quantity requirements generally make a single vice setup a good choice. The part configuration will point toward either contoured jaws or any number of standard or special jaws. The gripping area for the planned operation must allow for sufficient depth of jaw engagement (bite) to safely allow the planned operation to take place.

Higher quantity lot sizes make multiple vise setups desirable. The workpiecesize determines the spacing between the vises as well as the vise size itself. Generally, attempts must be made to produce the maximum amount of parts per cycle. Many additional operations by the same operator can then be done simultaneously. The key to freeing the operator is quick clamping and the highest efficiency of the workpieceloading cycle. This includes prepping the work area for thorough chip flushing and cleaning.

But in particular, with reference to this project, the vise design is guided by the following considerations;

1.         Adequate clamping forces

2.         Quick and ease of clamping

3.         Simple construction

4.         Low cost

5.         Durability