Machining method of low-noise worm gear

Abstract

The invention discloses a processing method of a low-noise worm gear, which is characterized in that the reference diameter of a worm gear hob used for processing the worm gear is 3-5 times larger than the reference diameter of a standard worm gear hob, and the lead angle of the worm gear hob is calculated according to the increased reference diameter of the hob and is smaller than the lead angle of the standard worm gear hob. Compared with the prior art that a standard worm gear hob with the same parameters as a worm meshed with the worm gear is adopted for machining the worm gear, some materials are evenly and symmetrically cut off at the two ends of the tooth direction of the machined worm gear, so that the machining precision of the worm gear is greatly improved. And equivalently, drum shape modification is performed on the worm gear in the tooth direction, and the contact area during meshing transmission of the worm gear and the worm is reduced, so that the meshing noise of the worm gear pair can be reduced.

Description

Technical Field

[0001] The invention relates to a method for processing a low-noise worm gear, and belongs to the technical field of worm gear processing. Background Art

[0002] In the prior art, when machining worm gears, a standard worm gear hob is usually used to machine the worm gear. The standard worm gear hob is usually designed according to the parameters of the worm gear meshing with the worm gear, and its main parameters such as module, pressure angle, pitch circle diameter, number of starts, helical direction and helix angle are all consistent with the meshing worm gear. When the worm gear machined by such a standard worm gear hob meshes with the worm gear, there is a disadvantage of large meshing noise due to the large contact area. Summary of the invention

[0003] The purpose of the present invention is to provide a method for processing a low-noise worm gear, so as to overcome the disadvantage that the worm gear processed by a standard worm gear hob has a large meshing noise.

[0004] The technical solution of the present invention is a method for processing a low-noise worm gear. The pitch circle diameter of a worm gear hob used for processing the worm gear is 3 to 5 times larger than the pitch circle diameter of a standard worm gear hob by the worm gear module, and the helix angle thereof is calculated based on the enlarged hob pitch circle diameter and is smaller than the helix angle of a standard worm gear hob.

[0005] In the aforementioned method for machining a low-noise worm gear, when machining the worm gear, the hob tool holder is rotated by an angle, the value of which is equal to the difference between the helix angle of a standard worm gear hob and a worm gear hob designed with an enlarged pitch circle diameter.

[0006] Beneficial effects of the present invention: The present invention adopts a worm wheel hob designed with an enlarged pitch circle diameter to process the worm wheel. Compared with the prior art that uses a standard worm wheel hob with exactly the same parameters as the worm gear meshing with the worm wheel to process the worm wheel, the processed worm wheel has more material evenly and symmetrically removed at both ends of the tooth direction, which is equivalent to drumming the worm wheel in the tooth direction, reducing the contact area when the worm wheel and the worm gear are meshing for transmission, and thus can reduce the meshing noise of the worm wheel pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a comparative diagram of the worm gear hob designed with an enlarged pitch circle diameter and the standard worm gear hob for machining worm gears;

[0008] Figure numerals: 1-standard worm gear hob; 2-worm gear hob designed with enlarged pitch circle diameter; 3-worm gear; 4-the thick line part is some material that is evenly and symmetrically removed at both ends of the worm gear. DETAILED DESCRIPTION

[0009] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0010] Embodiment of the present invention: A method for processing a low-noise worm gear, wherein the pitch circle diameter of a worm gear hob used for processing the worm gear is 3 to 5 times larger than the pitch circle diameter of a standard worm gear hob, and the helix angle thereof is calculated based on the increased pitch circle diameter of the hob, and is smaller than the helix angle of a standard worm gear hob. The module, pressure angle, number of heads, helical direction, worm type, and pitch circle normal tooth thickness of the worm gear hob are still completely consistent with those of a standard worm gear hob.

[0011] In order to ensure that the processed worm wheel and worm can mesh normally, the hob tool holder is turned an angle when processing the worm wheel, and its value is equal to the difference between the helix angle of the standard worm wheel hob and the worm wheel hob designed with an enlarged pitch circle diameter.

[0012] The working principle of the present invention is:

[0013] According to the following calculation formulas (1) and (2) for the helix angle of the worm gear hob, it can be known that as the pitch circle diameter d of the worm gear hob increases, the helix angle of the worm gear hob will gradually decrease. Therefore, when processing the worm gear, as long as the hob tool holder is turned by an angle (i.e., the difference between the helix angles of the standard worm gear hob and the worm gear hob designed with an enlarged pitch circle diameter), the helix angle of the processed worm gear can be guaranteed to be consistent with the meshing worm; in addition, since the module, pressure angle, number of heads, helix direction, worm type, and pitch circle normal tooth thickness of the worm gear hob designed with an enlarged pitch circle diameter are completely consistent with those of the standard worm gear hob, the worm gear hob designed with an enlarged pitch circle diameter can ensure that the processed worm gear and the worm are meshed normally.

[0014] λ=arctg(nm x / d) (1)

[0015] m x =m n / cosλ (2)

[0016] Where λ is the helix angle of the hob, n is the number of hob heads, d is the hob pitch circle diameter; m x is the axial modulus of the hob, m n is the normal module of the hob.

[0017] Taking a worm gear as an example, the design principle and processing method of increasing the diameter of the worm gear roller pitch circle of the present invention are explained below.

[0018] Worm gear parameters

[0019] The end module mt2=2.5, the number of teeth Z2=30, the normal pressure angle an2=20°, the helix angle β=5°6′8″, and the helix direction is right-handed.

[0020] The worm gear transmission type is normal straight profile.

[0021] Worm parameters

[0022] Axial module mx1=2.5, number of threads Z1=1, normal pressure angle an1=20°, helix angle λ=5°6′8″, helix direction is right-handed, normal tooth thickness Sn1=3.91 (-0.02 / -0.07), pitch circle diameter d1=28.

[0023] Since the design of the standard worm gear hob is based on the parameters of the worm meshing with the worm wheel, the design parameters of the standard worm gear hob are as follows:

[0024] Axial module mx = 2.5, normal pressure angle an = 20°, hob pitch circle diameter d = φ28, helix angle λ = 5°6′8″, hob helical direction is right-handed, number of heads k = 1, basic worm type is normal straight profile, normal tooth thickness Sn = 3.91 (-0.02 / -0.07).

[0025] According to the design principle of increasing the pitch circle diameter of the worm wheel roller of the present invention, the pitch circle diameter of the worm wheel hob is 4 times larger than the pitch circle diameter of the standard worm wheel hob, and the worm module is:

[0026] The pitch circle diameter of the worm gear hob is dtool1=dtool+4*mt2=28+4×2.5=38.

[0027] Worm gear hob helix angle λ1 = arctg (nmx1 / dknife1) = arctg (1×2.5 / 38)

[0028] =3°45′51″.

[0029] The remaining parameters of the worm gear hob are the same as those of the standard worm gear hob.

[0030] The turning angle of the hob tool holder = λ-λ1 = 5°6′8″-3°45′51″ = 1°20′17″.

[0031] When machining a worm gear, the hob cutter head only needs to be turned 1°20′17″ to ensure that the helix angle of the machined worm gear is consistent with the meshing worm.

[0032] The worm wheel in this example was processed by the worm wheel hob with a pitch circle diameter d1=38 and a helix angle λ1=3°45′51″. After assembly and testing, the meshing noise was reduced by an average of more than 6 decibels when the meshing worm was the same as that of the worm wheel in this example processed by a standard worm wheel hob with a pitch circle diameter d1=28 and a helix angle λ1=5°6′8″.

Claims

1. A method for processing a low-noise worm gear, characterized in that: The pitch circle diameter of the worm gear hob used to process the worm gear is 3 to 5 times larger than the pitch circle diameter of the standard worm gear hob, and its helix angle is calculated based on the enlarged hob pitch circle diameter and is smaller than the helix angle of the standard worm gear hob.

2. A method for processing a low-noise worm gear according to claim 1, characterized in that: When machining a worm gear, the hob holder is turned by an angle equal to the difference in helix angle between a standard worm gear hob and a worm gear hob designed with an enlarged pitch circle diameter.

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