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Preface With the development of gear transmission to high speed and heavy load, the dynamic performance of gear transmission has received more and more attention.
A large number of practical and theoretical analysis show that correct shape modification is an effective way to improve the quality of gear transmission. Modification technology has been widely used to reduce gear transmission vibration and noise.
The principle of the traditional gear tooth profile modification is to remove part of the material from the tooth top part or the tooth root part to compensate for the load deformation and the base joint error, reduce the gear biting and the impact of the gear, and achieve vibration reduction and noise reduction. purpose. The tooth profile modification parameters are currently estimated by the method of calculating the static elastic deformation of the gear teeth. Although the gear standard has established the basic tooth profile of the tooth profile modification, it is difficult to adapt to all because it is only related to the normal modulus. Working conditions. Based on the basic theory of B-spline curve and surface, the author reconstructs the tooth surface of the gear modification by using the cubic B-spline surface on the basis of the measurement of the tooth surface of the gear, and uses the finite element method to measure the contact strength of the tooth surface. Based on the simulation research and experimental analysis, the idea of ​​sinusoidal shaping curve is proposed. By comparing and combining B-spline shaping, the gear shaping curve and its parameters are optimized with the minimum vibration noise as the target. Tested and verified.
1NUBRS curve, surface basic equation 111NUBRS curve interpolation known spatial data points, using the cumulative chord length form to get the node vector T = [t0, t0, t0, t0, t1, t2, ..., tn-1, tn, tn, tn , tn, tn] then the three-time NUBRS curve equation is ∑n 2i=0Ni4(t)wiVi∑n 2i=0Ni4(t)wi=Pj(j=0,1,2,...n) where: Ni4=0ti= T15(2) Minimum tooth width limit: 82(4) Minimum contact strength limit: 1070m(z1 z2)(i 1)3kT1ib<855(MPa)(5) Minimum bending fatigue strength limit: 2kT1bd1my<26117(MPa) :k is the load distribution coefficient; i is the transmission ratio; T1 is the torque transmitted by the pinion; b is the tooth width; m is the gear modulus; y is the tooth profile; z1, z2 is the main and driven gear teeth; d1 is Pinion diameter.
314 Vibration and Noise Analysis In order to eliminate or reduce transmission errors, it is necessary to simultaneously modify the tooth profile and the tooth profile. The above dynamic analysis of the gear transmission system fully proves that the test results of the standard involute gear are corrected according to the required tooth profile when shaving; secondly, the corrected tooth profile is also required. A reasonable judgment is to determine whether the corrected graph meets the design requirements. The tooth profile design is based on the involute, and is corrected by factors such as manufacturing error and elastic deformation, dynamic load and heat treatment deformation. There are many ways to design tooth profiles today.
Or marked on a special craft card. The tester uses the transparent film to inspect and evaluate the manufactured gears to achieve the means of controlling the tooth shape modification. There is no uniform standard for the design of the tooth profile. Each enterprise can determine it according to the actual situation.
Comparison of the modification effects of several shaping curves under different working conditions In order to improve the tooth curve control, it is necessary to comprehensively evaluate the curve after shaving, although some of the tooth curves completely fall within the design tooth range, but the curve The morphological differences are large, and the designers expect an ideal convex tooth profile with a tooth top or root trim, but it is often difficult to obtain in actual production. Therefore, it is necessary to stipulate the corrected tooth profile, which are the tooth shapes that meet the design requirements, and which are the undesired tooth shapes, which need to be excluded. In the judgment, it can be judged as follows: (1) Whether the corrected tooth profile is convex near the index circle, and for the drive gear, whether the middle bump of the tooth curve is slightly higher than the index circle; for the driven gear Whether the middle bump of the tooth curve is slightly lower than the index circle; (2) The curve measured after shaving should be smooth, there should be no obvious bump points, and the individual bump points are not allowed to exceed the design tooth frame; (3) The shape modification curve should avoid the "S" shape curve; the length of the tooth top trimming edge should not be too long, and it is not allowed to approach the indexing circle or exceed the indexing circle; although the tooth shape is convex, the tooth top and the root root trimming The curve is too steep and should be excluded.
Of course, in the evaluation of the tooth profile, the profile of the design must be consistent with the ratio of the recorded curve. Several common tooth curves are listed.
4 Conclusion With the research of gear transmission and the improvement of gear manufacturing technology, the shaping technology of gears has been greatly developed. The tooth profile and tooth profile modification have been widely used, and the smoothness of gear transmission is obviously improved by trimming. The noise and vibration of the gears improve the bearing capacity of the gears and prolong the service life of the gears, which brings greater economic benefits to the gear manufacturers and users.