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Page 1: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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GEARS MACHININGGEAR TYPES• Cylindrical gears:

- spur- helical

• Bevel gears:- straight- curved (spiral)

• Worm wheels and worms

Page 2: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Involute tooth profile

Page 3: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Spur and helical gears cutting

METHODS:

• form milling – using a cutter (with the same edge profile as the shape of the tooth space) and a dividing device

• hobbing – using a hob and a generating process for creating a tooth profile

• shaping – using a shaper cutter and a generating process for creating a tooth profile

• broaching

Page 4: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear machining – form milling(single gear tooth cutter)

Page 5: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear machining – form milling

Page 6: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Gear milling – tollerances and surface finish

Type of cut IT Ra

Form milling – shape mill

9 – 11 3,2 - 6,3

End milling 8 - 9 3,2 - 6,3

Page 7: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear machining - hobbing• Hob – a tool designed as a worm shaped

cutter, which acts by the cutting as a worm cooperating with the machined gear wheel

Page 8: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Hobbing cutter

Page 9: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear hobbing

Page 10: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear hobbing

Page 11: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear hobbing machine tool

Page 12: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear hobbing machine tool

Page 13: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear hobbing – kinematic schema

Page 14: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear machining - shaping

• circular shaper cutter →

• rack shaper cutter

Page 15: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaping – a circular cutter

Page 16: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaping – a circular cutter

Page 17: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaping – the principle

Page 18: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaping – a circular cutter

Page 19: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaping – a rack cutter

Page 20: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Gear shaper with the rack cutter

Page 21: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Tollerances and surface finish

Type of cut IT Ra

Hobbing 5 - 7 0,8 – 3,2

Shaping – circular cutter 5 – 6 0,8 – 1,6

Shaping – rack cutter 4 - 5 0,8 – 1,6

Page 22: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Broaching

• Very productive method

• Broach has the shape of gear

• Ideal for internal gears– Tooth gaps one after another– All gaps simultaneously

Desc.:

1 – elongated body, 2 – teeth, 3 – gullets, 4 – teeth gaps, 5 – axis, 6 – follower end, 7 – pull end, 10 – outside shape of broach

Page 23: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Broaching• From a premachined hole a final gear is made

Page 24: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Broaching

Type of cut IT Ra

Roughing 5 – 6 0,8 – 1,6

Finishing 4 - 5 0,8 – 1,6

Page 25: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Spur and helical gears finishingMETHODS:

• shaving – for gears without heat treatment

• grinding – mostly for gears after heat treatment- form grinding

- involute - generating grinding

• lapping

• teeth rounding – creating a shape of tooth (in the direction parallely to the axis of rotation) to make changing gears easier

Page 26: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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GEAR WHEELS SHAVINGA gear wheel being shaved is

run in contact with a shaving cutter

Shaving cutter – HSS tool; teeth with serrations, which are acting in the shaving

Page 27: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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GEAR WHEELS SHAVINGThe gear and the cutter are run in mesh with their axes

crossed at a small angle. During the rotation the gear is reciprocated longitudinally across the cutter.

This „shaving“ process causes very fine chips are cut from the tooth surface (process requires less than 1 minute)

Page 28: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Form gear grinding

Page 29: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Form splining grinding

Page 30: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Involute-generating grinding

Page 31: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Involute-generating grinder

Page 32: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Involute-generating grinder

Page 33: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Gear finishing – tollerances and surface finish

Type of cut IT Ra

Shaving 5 - 6 0,4 – 0,8

Form grinding 5 – 7 0,2 – 1,6

Involute-generating grinding with straight-sided grinding

wheels2 - 4 0,2 – 0,4

Involute-generating grinding with a worm grinding wheels

3 - 5 0,2 - 0,8

Page 34: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Gear lapping• On finished, shaved and hardened gears.• The gear runs in contact with one or more cast

iron lapping gears• Flow of oil with abrasive is used• Improves surface quality at low costs then

grinding• Ra = 0,1 – 0,2

Page 35: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Teeth rounding

Page 36: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Teeth rounding

Page 37: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Straight bevel gears cutting

METHODS:• form milling – using a cutter (with the same

form as the tooth face) and creating first one, than the opposite face flank of the tooth

• involute-generating milling– using two cutters representing one tooth of a rack and a generating process for creating a tooth profile

• shaping – using a shaping rack tool and a generating process for creating a tooth profile

• broaching – using rotational broach

Page 38: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Straight bevel gears involute-generating milling

Page 39: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Straight bevel gears - shaping

Page 40: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Straight bevel gears - broaching

Page 41: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Straight bevel gears - broaching

Page 42: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Curved bevel gears cutting

METHODS:

• Gleason – teeth curved in the form of circle

• Oerlikon – teeth curved in the form of epicycloid

• Klingelnberg – teeth curved in the form of involute

Page 43: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Gleason method

Tool is a composition of a round body and cutting tools. The can be adjusted separatelly.

Page 44: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Curved bevel gears - Oerlikon

Page 45: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

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Curved bevel gears - Oerlikon

Page 46: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Worms and worm gears

Worms – produced by turning or form milling

Page 47: 1 GEARS MACHINING GEAR TYPES Cylindrical gears: -spur -helical Bevel gears: -straight -curved (spiral) Worm wheels and worms.

Worms and worm gears

Worm gears – produced by hobbing

Worm hob has a small diameter

In feed machining