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Gear Shop
Gear Shop
Introduction : In gear shop the components which have gear like appearance are manufactured . A number of operation are done on these components

1. P.T.O Differential
2. B.P. left 13 teeth
3. I.C. 15/21
4. Gear 35/17
5. Gear 28/17
6. Pinion RH z=16
7. Pinion RH z=16
8. Sleeve 222037
9. B.P. left-12t
10. Idler Cluster
11. Intermediate Shaft
12. Input Shaft
13. Main Shaft
14. Counter Shaft
15. Shaft Serrated Hydraulic Lift
16. Drive Shaft


MACHINE USED

Following machines are used in GEAR SHOP

1. Broaching m/c
2. Hobbing m/c
3. Shaving m/c
4. Gear shaper
5. Divering m/c
6. Milling m/c
7. Lathe m/c
8. Drilling m/c
OPERATIONS PERFORMED

Following are the operations performed in this shop

1) Broaching
2) Hobbing
3) Shaving
4) Deburring
5) Shaping
6) Milling
7) Drilling
8) Grinding
i. Cylindrical grinding
ii. Surface grinding

BROACHING

Broaching is a method of removing metal by pushing or pulling a cutting tool called a broach, which cuts in a fixed path. The tool may be pulled or pushed through the surface to be finished. Surfaces finished by broaching may be flat or contoured and may be either internal or external. Broaching is limited to the removal of about 6 mm of stock or less.

A Broach is a multiple edges cutting tool has successively higher cutting edges along the length of tool.

Types of Broaches: Broaches may be classified in various ways according to

1) Type of operation: internal or external
2) Method of operation: push or pull
3) Type of construction: solid, built up, inserted tooth, progressive cut, rotor cut, double jump, overlapping tooth.
4) Function: surface, keyway, round hole, splint, spiral, burnishing, etc.
HOBBING

It is a process of generating a gear by means of a cutter, called a hob that revolves and cuts like a milling cutter. A hob may be briefly described as a fluted steel worm, equipped with proper clearance for cutting action. Flutes are cut across the threads, forming rack-shaped cutting teeth. The threads may be right or left-hand, and flutes may be straight or helical. A hob may have one, two or more threads. Single thread hob are generally used, although where a high degree of accuracy is desired on gears of coarse pitch, a roughing cut is taken with double or triple thread hobs and the finishing cut is taken with single thread hob. A single thread hob cuts but one tooth, where as double thread hob cuts two teeth concurrently.

In gear hobbing, the gear blank is first moved in towards the rotating hub until the proper depth is reached. The action is same as if the gears are meshing with a rack. As soon as the proper depth is reached, the hob cutter is fed across the face of the gear until the teeth are completed, both gear and cutter rotating during the entire process.



GEAR SHAVING
Gear shaving is basically a finishing operation. This takes place after the operations of roughing with a hob or cutting with a shaper cutter is over. The Shaving process consists of the removal of tiny particles of metal from a gear teeth's working surface. Gear shaving produces fine hairlike chips. The cutter comes in the form of helical gear. It has special serrations in the flank area of a gear teeth. These serrations act as the cutting edges.

Advantages
Gear Shaving gives the gear the following advantages:
• Improves tooth surface finish.
• Eliminates, the problem of tooth end load concentrations.
• Effective reduction in the noise of gears with modification in the tooth profile.
• Increase the gear’s load capacity Improved safety and service life.


GEAR DEBURRING

The Deburring process of gears makes the parts capable of a performance for which they were designed. It eliminates all the unwanted elements that obstructs their productivity. Over the years deburring process has changed considerably. There have been rapid advancements made with regard to the types of tools used for deburring ope»
There are two types of gear deburring machines
• Dry Deburring Machines
The dry machine is named like this because here the deburring operation taking place is dry. These e machines are normally fitted with a dust collection system. Deburring through a dry machine is accomplished very well if the parts are cleaned and dried before hand.

• Wet Deburring Machine
In case of a wet deburring machine, a rust preventative non-foaming is applied in the parts on an on going deburring process. This makes the part clean and can flush away the deburred particles. Subsequently the part is blown dry while the rust preventative continues to stay on the part as a protective film.rations.

GEAR SHAPING
The cutter is a circular pinion-shaped cutter with the necessary rake angles to cut as shown. Both the gear blank and cutter are set in a vertical plane and rotated such as that the two are like gears in mesh. Gear shaping is faster than gear planing because the cutting process is continuous and the cutter does not have to be stepped back. This is the most versatile gear cutting process which could produce internal and external gears, close-coupled cluster gears and splines too.


MILLING

Introduction: A milling machine is a machine is a machine tool that removes metal as the work fed against a rotating multipoint cutter. The cutter rotates at a high speed and because of multipoint cutting edges it removes metal at a very fast rate. The machine can hold one or more number of cutters at a time.
This is why milling finds wide applications in production work. This is superior to other machines as regard accuracy and better surface finish, and is designed for machining a variety of tool room work.

Side Milling: The side milling is the operation of production of a flat vertical surface on the side of the work piece by using side milling cutter. The depth of cut is adjusted by rotating the vertical feed screw of the table.

Face Milling: The face milling is the operation performed by the milling cutter to produce a flat machine surface per perpendicular to the axis of rotation of cutter. The peripherical cutting edges of the cutter do the actual cutting, where as the face cutting edges finish up the work surface by removing a very small amount of material. In face milling operation both the up and down milling may be considered to be performed simultaneously on the work surface.
When the cutter rotates through half of revolution, the direction of ro]tation of the cutter tooth is opposite to the direction of feed and the direction reverses when the cutter rotates through other half of revolution. The thickness of the chip is minimum at the beginning and at the end of the cut, and it is maximum when work passes through the centerline of the cutter.


[b
DRILLING[/b]
Introduction: The drilling machine is one of the most important machine tool in the workshop. As regards its importance it is second only to the lathe. Although it was primarily designed to originate a hole, it can perform a number of similar operations. In a drilling machine holes may be drilled quickly and at a low cost. The hole is generated by the rotating edges of a cutting tool known as the drill, which exerts large force on the work clamped on the table.
As the machine tool exerts vertical pressure to originate a hole it is loosely called as ‘drilled press’.


GRINDING
Introduction: grinding is a metal cutting operation performed by means of rotating abrasive wheel which acts as a tool. This is used to finish the work piece, which must show a high surface quality, accuracy of shape and dimension. Columns and struts are shaped and finished mostly with the grinding machine.
Mostly grinding is a finishing operation because it removes comparatively little metal, 0.252 to 0.50 mm in most operations and the accuracy in dimension in order of 0.000025 mm. Grinding is also done to machine material which are too hard for other machining methods that use cutting tool.
Cylindrical grinding:
• Cylindrical grinding is also called center-type grinding and is used in the removing the cylindrical surfaces and shoulders of the workpiece. The workpiece is mounted and rotated by a workpiece holder, also known as a grinding dog or center driver. Both the tool and the workpiece are rotated by separate motors and at different speeds. The axes of rotation tool can be adjusted to produce a variety of shapes.
Process Characteristics
• Creates a piece that is formed, straight or tapered.
• Can only be cylindrical in shape
• Is a final machine process used to create highly accurate and smooth surfaces

Lubrication and Cooling
The use of fluids in a grinding process is necessary to cool and lubricate the wheel and workpiece as well as remove the chips produced in the grinding process. The most common grinding fluids are water-soluble chemical fluids, water-soluble oils, synthetic oils, and petroleum-based oils. It is imperative that the fluid be applied directly to the cutting area to prevent the fluid being blown away from the piece due to rapid rotation of the wheel.
Surface grinding:

This is perhaps the most fundamental of operations. Surface grinding is the process of providing precision ground surfaces either to a critical size or for the surface finish. In other words, it accurately processes or grounds a surface. Parts require surface grinding for various reasons like:
• Produce a flat surface.
• For specifying accurate tolerance thickness.
• A very smooth surface roughness is required.
• For sharpening of cutting tool.