DESIGN AND FABRICATION OF PNEUMATIC DRILL JIG

 

DESIGN AND FABRICATION OF PNEUMATIC DRILL JIG

ABSTRACT

The name of our academic project for Btech 4th year is “DESIGN AND FABRICATION OF PNEUMATICS DRILL JIG”.

As the name suggests a pneumatics drill jig is a very commonly used apparatus . It is widely used in manufacturing and fabrication industries.

Our project is not an original idea but some sort of case study and a learning experience and a stepping stone to go higher in our engineering field.

Manufacturing and fabrication industry is a very vast section of the mechanical engineering department. But this is a field of infinite opportunity for research and development. And in this manufacturing and fabrication industry drilling operation is a major part. Everyday things which we see the product we use gas gone through some sort of drilling operation in it's production journey. This fact cannot be denied. Thus we can surely say that drilling plays a major part in the manufacturing and fabrication industry.

In the Research and Development department every day breakthroughs are made. Every day a new modification, a new invention, a new idea is generated. But implementing these ideas, this design modification is a huge task. The journey of thinking and visualizing an idea and putting them into practical use is truly difficult.

We have tried to make a small design of a Pneumatics drill jig. It is not for practica; used but only for academic project purposes. The working principle is very simple and flawed

FUNDAMENTAL PRINCIPLES OF JIGS DESIGN 

1. LOCATING POINTS: Good facilities should be provided for locating the work. The article to be machined must be easily inserted and quickly taken out from the jig so that no time is wasted in placing the workpiece in position to perform operations. The position of the workpiece should be accurate with respect to tool guiding in the jig or setting elements in the . 

2. FOOLPROOF: The design of jigs  should be such that it would not permit the workpiece or the tool to be inserted in any position other than the correct one.

3. REDUCTION OF IDLE TIME: Design of Jigs  should be such that the process, loading, clamping and unloading time of the workpiece takes minimum as far as possible.

4. WEIGHT OF JIGS : It should be easy to handle, smaller in size and low cost in regard to the amount of material used without sacrificing rigidity and stiffness.  

5. JIGS PROVIDED WITH FEET: Jigs sometimes are provided with feet so that it can be placed on the table of the machine.  

6. MATERIALS FOR JIGS : Usually made of hardened materials to avoid frequent damage and to resist wear. ExampleMS, Cast iron, Diesteel, CS, HSS.

7. CLAMPING DEVICE: It should be as simple as possible without sacrificing effectiveness. The strength of the clamp should be such that not only to hold the workpiece firmly in place but also to take the strain of the cutting tool without springing when designing the jigs . 

ESSENTIAL FEATURES OF JIGS  

1. Reduction of idle time – Should enable easy clamping and unloading such that idle time is minimum  

2. Cleanliness of machining process – Design must be such that not much time is wasted in cleaning of scarfs, burrs, chips etc.

  

3. Replaceable part or standardization – The locating and supporting surfaces as far as possible should be replaceable, should be standardized so that their interchangeable manufacture is possible  

4. Provision for coolant – Provision should be there so that the tool is cooled and the dwarfs and chips are washed away  

5. Hardened surfaces – All locating and supporting surfaces should be hardened materials as far as conditions permit so that they are not quickly worn out and accuracy is retained for a long time  

6. Inserts and pads – Should always be riveted to those faces of the clamps which will come in contact with finished surfaces of the workpiece so that they are not spoilt  

7. Fool-proofing – Pins and other devices of simple nature incorporated in such a position that they will always spoil the placement of the component or hinder the fitting of the cutting tool until the latter are in correct pos 

 

8. Economic soundness – Equipment should be economically sound, cost of design and manufacture should be in proportion to the quantity and price of producer  

9. Easy manipulation – It should be as light in weight as possible and easy to handle so that workman is not subjected to fatigue, should be provided with adequate lift aids  

10. Initial location – Should be ensured that workpiece is not located on more than 3 points in anyone plane test to avoid rocking, spring loading should be done  

11. Position of clamps – Clamping should occur directly above the points supporting the workpiece to avoid distortion and springing  

12. Clearance – Sufficient amount of clearance should be provided around the work so that operator’s hands can easily enter the body for placing the workpiece and any variations of work can be accommodated  

13. Ejecting devices – Proper ejecting devices should be incorporated in the body to push the workpiece out after operation  

14. Rigidity and stability – It should remain perfectly rigid and stable during operation. Provision should be made for proper positioning and rigidly holding the jigs   

15. Safety – The design should assure perfect safety of the operator.

GENERAL RULES FOR DESIGNING 

1. Compare the cost of production of work with present tools with the expected cost of production, using the tool to be made and see that the cost of buildings is not in excess of expected gain.

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2.  Decide upon locating points and outline clamping arrangements.

 

3. Make all clamping and binding devices as quick acting as possible. 

4. Make the jig fool proof. 

 

5. Make some locating points adjustable. 

6. Avoid complicated clamping arrangements.

 

7. Round all corners. 

8. Provide handles wherever these will make handling easy. 

9. Provide abundant clearance.

 

10. Provide holes on escapes for chips. 

11. Locate clamps so that they will be in the best position to resist the pressure of the cutting tool when at work.

12. Place all clamps as nearly as possible opposite some bearing point of the work to avoid springing action. 

13. Before using in the shop, test all jigs as soon as they are made.

MATERIALS USED 

Jigs are made of a variety of materials, some of which can be hardened to resist wear.  

Materials generally used:  

1. High speed Steel: Cutting tools like drills, reamers and milling cutters.

  

2. Die steels: Used for press tools, contain 1% carbon, 0.5 to 1% tungsten and less quantities of silicon and manganese. 

 

3. Carbon steels: Used for standard cutting tools.  

4. Collet steels: Spring steels containing 1% carbon, 0.5% manganese and less silicon.  

5. Non shrinking tool steels: 

• High carbon or high chromium 

• Very little distortion during heat treatment. 

• Used widely for fine, intricate press tools. 

6. Nickel chrome steels: Used for gears. 

7. High tensile steels: Used for fasteners like high tensile screws 

8. Mild steel: 

• Used in most parts of Jigs 

• Cheapest material 

• Contains less than 0.3% carbon 

9. Cast Iron: 

• Used for odd shapes to some machining and laborious fabrication 

• CI usage requires a pattern for casting 

• Contains more than 2% carbon 

• Has self lubricating properties 

• Can withstand vibrations and suitable for base

10. Nylon and Fiber: Used for soft lining for clamps to damage to workpiece due to clamping pressure. 

11. Phosphor bronze: used for nuts as have high tensile strength Used for nuts of the lead screw.

WORKING PRINCIPLE

The full design consists of many parts. The working principle of this drill jig is very simple.

  First we can see a frame into which there are many apparatus attached. The upper plate the lower plate the single acting pneumatic actuator or the single acting pneumatic cylinder. 

The upper and the lower plates consist of clamping bars which are textured or knurled for gripping purposes. The lower plate is attached with the frame and the upper plate is attached with the adjustable plate which can be moved up and down using the pneumatic actuator or pneumatic cylinder. 

The upper plate and the adjustable plate are connected with four numbers of blots and nuts. So when the adjustable plate is linearly moved so that the upper plate moves with it. The adjustable plate is fixed to the pneumatic cylinder and the pneumatic cylinder is connected to the main frame.

So the upper plate is facilitated with a through hole. The through hole is surrounded by a bush which helps to guide the drill bit in precise position. 

The job or the work piece is loaded between the upper plate and the lower plate. The job or workpiece is situated between the clamping bars. After positioning the job or working piece in the desired position, the pneumatic cylinder or the pneumatic actuator is switched on. Compressed air passes through the valve and into the actuator. When the actuator is activated. The cylinder piston moves down. As the piston moves down, the adjustable plate also moves down. As the adjustable plate moves down the upper plate also moves down as it is connected to the adjustable plate with nuts and bolts. Thus clamping the job or the work piece.

No the job or the workpiece is clamped in the proper position, it cannot be moved. Now the drilling operation is done. After the drilling operation is done the pneumatic valve is reverted. Thus letting the air inside the pneumatic cylinder to release and returning the piston into its original position.

As the piston retract to its original position the adjustable plate moves up with the cylinder piston. And with the adjustable plate the upper plate also moves up thus releasing the job or the workpiece. 

Now the job or the work piece is free to be moved.

 

SYNOPSIS

As this is an academic project, the design and the working is impractical for industrial use. By doing this project we dive deep into the daily life problems faced in the manufacturing and the fabrication industry.

Today's life is very fast paced. Everybody needs things in advance, fast with assured quality. But production is a very difficult task to keep on going at this fast pace with assured quality. Thus the engineering field is developing and trying to cope up with the demand faced by the huge population of the earth.

This project deals with the real life problem in the manufacturing and fabrication industry. A small saving of time is also crucial in the production line. This drill jig shows us that a job can be loaded and unloaded in a job station very quickly without wasting any time for other additional arrangements.

You may question what productivity does this clamping device increase. For your answer - if we look at big industries, we can see that every job is done by robots. One robot does a work equal to 10 men at the same time. We can see that a robot can hold, position, guide, transport, transfer, and also do the machining operation at the same time. This not only saves time but also productivity and space.

Thus automatic operation is the future of our engineering industry. And this automatic operation has a long way to go and many more advancements to be done.

 

 

CONCLUSION

We have done this academic project on “DESIGN AND FABRICATION OF DRILL JIG”

We have learnt many things about the manufacturing and the fabrication industry. This project has helped us to understand the importance of time management in large scale production.

We have learnt that designing and fabrication is not as easy as it looks. A lot of work is put into effect for a small job to be done. It has made us realize the importance of manufacturing. We have a whole new perspective about the small things that we use in our day to day life.

Once again we thank PROJECT GUIDE  Dr SUBHAS CHANDRA MOI and Prof RAJEEV RANJAN for giving us the opportunity to do this project under their guidance.

Thank you