Precision forming method of straight/helical tooth cylindrical gear

Abstract

The invention relates to a precise forming method of a straight/helical tooth cylindrical gear. The precise forming method disclosed by the invention is characterized by being realized by the following two steps while a 'diameter-increasing half long ridge-tooth space splitting' way is adopted: firstly, closed die forging is carried out on cylindrical blank to form a pre-formed part, wherein one end of the pre-formed part is larger in radial dimension, sectional area and edge axial dimension and the other end of the pre-formed part is equal to the required value of the sectional area and has slightly smaller radial dimension, the two ends transit in a bevel angle manner, and a cylindrical surface is in a 'diameter-increasing half long ridge' state; and secondly, the pre-formed parts penetrate through a final forming die each tooth space of which is correspondingly provided with a splitting wedge in a sequence from big end to small end, wherein a splitting edge and a working surface of the splitting wedge are in a tilted state, a rim is split, extruded and deforms, and each slot base is deepened and the top of each ridge is lifted, thus a gear tooth with complete tooth profile is obtained. The gear tooth/tooth space obtained by the invention is clear and full, a required forming force is relatively small, an equipment action is simple, a structure of a die is not complex, a workpiece is easy to demould, requirement to technological conditions is low, and adaptability is wide.

Description

technical field [0001] The invention belongs to the technical field of metal plastic forming technology, is mainly used in the manufacture of mechanical parts, relates to a gear precision forming method and a mold thereof, and is especially suitable for spur or helical cylindrical (cylindrical or non-cylindrical) gears with equal tooth cross-section shapes everywhere Precision formed. Background technique [0002] Cylindrical gears (hereinafter referred to as gears) are a large-scale and wide-ranging mechanical basis for transmitting force and motion. They are generally composed of hubs, spokes, and toothed rims, while internal gears are mainly composed of toothed rims. According to the shape of the tooth line, there are spur gears, helical gears, and herringbone gears. [0003] In addition to straight-toothed thin-plate (the height of the rim is obviously smaller than the radial dimension) gears can be obtained by blanking from the sheet metal, the traditional gear manufac...

AI Technical Summary

Problems solved by technology

The traditional mainstream method has the following disadvantages: 1) The streamline of the forging structure is cut off, which reduces the mechanical properties of the gear teeth; 2) The cutting process occupies a large number of equipment and consumes a lot of man-hours, and the number of workpiece turnovers is high, the production cycle is long and the efficiency is low; 3) Low material utilization rate, high energy consumption and high manufacturing cost

[0025] The disadvantages of this approach are: 1) "open forming" weakens the strength of the die corresponding to the alveolar, and it is difficult to demould; 2) shaping can easily cause edge collapse; 3) the number of steps required and the number of molds are relatively large. many, low efficiency

[0028] 1) It is difficult to fill the tooth corners of the full-ridge approach, and it is difficult to demould the workpiece

[0029] 2) The mold structures required for floating die forming, closed die forging, and split flow forming are complicated, and the required equipment actions are complicated

[0030] 3) The tooth part of split forming needs to enter the same mold cavity twice, and there is a certain waste of material

[0031] 4) The full slot method is difficult to apply to the gear forming with large radial size and large modulus

[0032] 5) The full-ridge approach and the full-groove approach require a large forming force, and the service conditions of the mold are harsh

[0033] 6) "Pushing" directly with a cylindrical blank will form a confluence fold at the top of the tooth, and the edge of the starting end will be severely collapsed

[0034] 7) The first step of the "open ridge-groove expansion" method weakens the strength of the die, and the subsequent steps are likely to cause edge collapse, and the number of steps and molds required is large and the efficiency is low

[0035] The main reasons for the many shortcomings of the existing technology are: 1) The forming method is unreasonable; 2) There is no pre-forming or the pre-forming is unreasonable; 3) The shape of the final forming die is unreasonable

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