Prepared By :-Sumesh Vijayan

08626 G

Gear shaping is a machinery process for generating teeth by a corresponding cutter. Gear shaping has become a convenient operation and one of the most versatile of all gear cutting operations.

By using a gear-shaped corresponding cutter that is rotated (in relation to a blank gear) produces the gear teeth.

The cutters that are rotated are timed with the workpiece.

This process produces internal gears, external gears, and integral gear-pinion arrangements.

The developing process of gear shaping involves a toothed disk cutter which reciprocates in axial rotations. The workpiece (or blank gear) rotates on a second shaft (spindle). The workpiece is correspondent with the cutter and it gradually feeds into the cutter while rotating. If a two-step process is used, all tooth spaces are partially cut before the finishing.

The machine used for gear shaping generally consists of a base, column spindle, and an arbor.

The gear cutter is then mounted on the spindle, and the gear blank is mounted on the arbor.

The cutter reciprocates up and down while the work piece is gradually fed into the cutter.

There are following types of Gear Shaper cutter available:

Disc Type Shaper Cutter

Shank Type Cutters

Disk Type Helical Shaper Cutter

Deep Counterbore Type Shaper Cutter

Coniflex CutterPinion Type Cutter

Spiral Bevel Cutter

*Disc Type Shaper Cutter:Disc type cutters are effective for cutting any type of gear. Internal, external, spur, helical etc. Popular cutters have bore diameters between 10mm-120mm or ½" to 4".

*Shank Type Cutters:They are essentially designed to cut internal gears, both spur and helical. Can also be designed for externals. A bit of problem in the shank type cutters is the strength factor.

*Disk Type Helical Shaper Cutter:This cutter is applied to cut helical gears. The helix angle of the gear determines the number of teeth that the cutter would have.

*Deep Counterbore Type Shaper Cutter:This type of cutter is commonly applied to cut shoulder gears.

*Pinion Type Cutter:Pinion type cutters are typically shaped like spur gears. The Pinion type cutters are adept in cutting teeth of the internal gears.

*Coniflex Cutter:Straight Bevel Gears are easily cut with Coniflex gear cutter. Coniflex gear cutters produce gear teeth with an accurate tooth contact. So the gears made this way operate in a smooth fashion.

*Spiral Bevel Cutter:As is seen from the image Spiral Bevel cutters are shaped like crowns and they are used to generate Spiral Bevel gears.

Due to high economical efficiency, the gear shaving process is widely used process for soft finishing of gears in the manufacturing industry.

However due to high increased efficiency, other gear finishing processes, especially Gear Hobbing have recently become competitive with the shaving process for soft finishing of gears.

It is cold working process accomplished by rolling the gear in contact and under pressure with three hardened burnishing gears.

In this case, a cutter harder than the work and in the form of conjugate gear which meshes with it in such a way that when rotated together, relative sliding between the cutter and work teeth obtains, is used.

In action one member of the pair is driven and makes the other rotate.

The value of the crossed axis angle controls the finish produced to some extent since smaller the angle, finer the finish.

Shaving improves gear tooth finish where the cutting process has not provided the required standard. The process is ideal for automotive gear box gears after hobbing and before hardening.

There is a wide range of available shaving cutter types:

Transverse Shaving Cutters

Diagonal Shaving Cutters

Plunge Shaving Cutters

Underpass Shaving Cutters

• The gear that is shaved reciprocates in the direction of its own axis.

• The tool and the gear are in mesh.

• With each step of reciprocation, there is an occurrence of small quantity of radial feeding of the shaving cutter.

• However, this method is not suited to shaving shoulder gears.

• Here the gear selected for shaving reciprocates obliquely in direction to its own axis.

• The gear and the tool are made to stay in a mesh.

• The diagonal angle can be got by positioning of the workpiece table in an oblique manner.

• As with each reciprocation, there is a radial feeding of the shaving cutter.

• This is described in the diagram:

• In this method there is no worktable translation.

• Instead there takes place a radial feed of the workpiece against the tool that is used as shaving cutter.

• Plunge shaving is particularly good for shaving of shoulder gear.

• Underpass shaving is primarily identical to diagonal shaving with a small variation in the form of a diagonal angle of 90 degrees.

• In underpass shaving no axial table reciprocation takes place.

• In its place, the workpiece reciprocates at right angles to its own axis.

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.

The surface of the tooth is covered with amorphous or smear metal rather than metal having true crystalline structure.

Wikipedia

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Production Technology by R.K. Jain

Gear Technology.com

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