Gear Teeth Finishing

What are the various methods of gear teeth shaving and grinding involute helical bevel gears? And can these operations be performed on the same machines that process common bevel gears?

This paper describes methods of tooth shaving and grinding at HB gears of involute-bevel gearings. Furthermore, the opportunity of doing these operations on machines for teeth processing in common gear types are shown.

The possibility of these operations performance on the equipment that is used for common helical gears teeth processing is showed. ©2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/).

Gear Teeth Shaving

This paper describes involute helical-bevel gearing (HBG). The involute helical-bevel gearing commonly includes a cylindrical and a involute-bevel gear [1, 2]. This gearings can be designed for any position of the shaft axes [3-5]. Due to a number of advantages (arrangement, exploitative, technological) involute HBG is using in many directions of mechanical engineering (motor car construction, shipbuilding, space equipment) [6-10].

It is known that in helical-bevel gearing line contact of gears is possible with certain combination of parameters
for one direction of rotating between skew axes.

This condition is obtained on the basis of equality to zero between linear generatrices of involute helicoids of
gears. These linear generatrices are lines of contact between tooth of the gear and counterpart rack while cutting.

If cylindrical cog-wheel in the gearing will be replaced by shaver, that is identical in geometry to it, then cutting edges of shaver will machine all collateral border of tooth of the conical gear at once during rotation with enough width. The processing is did without changing relative position of the shaver and gear by single-flank gearing scheme with blank rotation slow downing. Shavers must have different in algebraic sign incline angles of teeth for processing left and right side of cog.

Line contact condition of teeth in gearing are observed only with one side of tooth contact, using this shaving
method for bevel gear teeth. Point contact take place for working of teeth other side. This localization lower load-carrying capacity of reversal gear drive. One is effective methods of increasing load-carrying capacity in this case is using gearing implementation with modified tooth profile. Longitudinal modification allows to get theoretically line contact of working flanks and to align load-carrying capacity of the gearing in the contact with both flanks of the tooth. This modification can be did by shaving helical gears with involute-bevel shaver with parameters, which is identically to bevel gear parameters in the gearing. on flanks The modified profile of gear tooth working flanks implement point wise in the result of shaving by this shaver, which provide theoretically line contact with involute-bevel gear teeth by the second Olivier method. The cutting edges will process all side flanks at once with enough length of the involute-bevel shaver.

Involute-bevel shaver for processing helical spiral gear in gearing with crossing axes is shown on fig. 2, where E
= 10°, m = 5, number of bevel gear teeth is z2 =21, number of helical gear teeth is z2 =24. Relative position of involute-bevel shaver and shaving gear are being calculated on formulas (10-13) using this shaving method.

Processing is did using the single-flank gear scheme like as the first time. Cutting speed is teeth longitudinal sliding speed with previously mentioned methods of shaving.

If gear hone will be used instead of the shaver, then HBG wheel teeth honing could be did.

Helical-bevel gearing wheel teeth grinding

Equipment, which is used for helical gears teeth grinding in helical-bevel gearings, is similar to equipment for
common gears. It is necessary to incline blank axis on angle concerning to feed longitudinal direction of grinding
wheel in teeth grinding, with angular equal-velocity joint arbors (fig. 3, a) or to provide grinding wheel motion using this angle to blank axis, like it is did in circular cutter (fig. 3, b). Machine adjustment to require angle can be did by installing appropriate wedges under of grinding wheel head guide of machine in serial processing involute-bevel gears. Such adjustment was done at “Nails” machine for grinding involute-bevel gears of marine reducers [1].

Conclusion

Methods of helical-bevel gearing finishing processing, which are shown in article, show, that same devices are
might be used for this as in processing of helical gears. This allows to receive high precision of HBG, which is
similar to bevel gearings.