1. The accuracy of gears is mainly to control the precision of the transmission of gears between running gears. For example: the smoothness of the transmission, the volatility of the instantaneous degree, and if there is alternating operation in reverse, whether the backlash of the teeth is at its minimum, if there is The impact load should slightly increase the accuracy, so as to reduce the damage caused by the impact load to the gear.
2, if the above design requirements are relatively high, the gear accuracy must be set slightly higher, and vice versa.
3. However, if the gear precision is set too high, it will increase the processing cost and require comprehensive balance.
4. The parameters above are basically gears that are more commonly used. The accuracy can be defined as: 7FL, or 7-6-6GM.
7FL: The tolerance of the three tolerance groups of the gear is the same as that of the 7th gear, the upper deviation of the tooth thickness is F-class, and the lower deviation of the tooth thickness is L-class.
7-6-6GM: The accuracy of the first set of tolerances of the gears is 7 and the accuracy of the second set of tolerances of the gears is 6. The tolerance of the third set of gears is 6 and the upper deviation of the tooth thickness is G. , The deviation of tooth thickness is M level
5, there is no formula for the accuracy of the gear, because there is no need for calculation, it is to check the manual.
6, the determination of the accuracy level is the result of comprehensive analysis of engineers, the transmission requirements of precision, or a high load, alternating load ... ... the accuracy level will be set a little higher
7, the accuracy level of 5,6,7,8,9,10, the smaller the value the higher the precision
8. The (tooth thickness) deviation level is also the grade given by the designer for the specific conditions. The precision transmission gives a little more, the general machinery gives a little lower, the closed drive gives a little more, and the open drive gives a little lower.
9, (tooth thickness) deviation class C, D, E, F, G, H, J, K, L, M, N, P, R, S level, C-level maximum clearance, S-class gap minimum.
10. Regardless of the accuracy level or the deviation level, the higher the setting, the higher the processing cost. After a comprehensive analysis, a specific accuracy level and deviation level should be given.
11. For the conventional inspection items of gears, there are three groups of inspection items, which are as follows:
12. The first group of inspection items is mainly to ensure the accuracy of the transmission movement. The items include: tangential comprehensive tolerance Fi', weekly cumulative tolerance Fp, k circumferential cumulative tolerance Fpk, radial comprehensive tolerance Fi", ring gear Radial Runout Tolerance Fr, Common Normal Length Variation Tolerance Fw
13. The second group of inspection projects is mainly to ensure the smoothness, noise and vibration of the transmission movement. The items include: tangential one-tooth synthetic tolerance fi', base section limit deviation fbp, weekly section limit deviation fpt, radial one tooth synthesis Tolerance fi"
14. The third group of inspection items is mainly to ensure the uniformity of the load distribution. The items include: tooth-tooth tolerance Fβ, contact line tolerance Fb, axial pitch limit deviation Fpx
15. Accuracy grades of gear tooth blank tolerance: 5, 6, 7, 8, 9, 10 grades
16, hole in the middle of the gear tolerance, and its geometric tolerance: IT5, IT6, IT7, IT8 level
17. Dimensional Tolerance of Gear Shafts and Formal Position Tolerances: IT5, IT6, IT7
18. Top circle diameter tolerance: IT7, IT8, IT9
19. Radial runout of the reference plane and end surface runout of the reference plane: According to the size of the diameter, check the table according to the size of 5, 6, 7, 8, 9, 10
20, need to explain: I gave the first group, the second group, the third group of inspection projects is more complete, but in reality, in the actual drawings, we do not have so many inspection projects Too many tests not only cause troubles for the inspection, but also increase the manufacturing cost. Therefore, only a few of them can be checked on the drawings. You can refer to the professional gear drawings, and you can also look at the Mechanical Design Manual. For example, here's a list of items that are routinely checked and listed on the drawing:
21, pinion inspection items:
21. According to the parameters you gave above, the precision level of the pinion gear can be set to 7FL, and the next level is the accuracy level difference manual:
22, week accumulation tolerance Fp: 0.063
23, week limit deviation fpt:0.018
24. Tooth tolerances marked on the drawings: Inner hole according to IT7 level: Check the "Standard tolerance table" according to the hole size in the manual.
25, the top circle radial runout: check the "standard tolerance table" according to the size of the outer diameter
26, large gear test items:
27、 Weekly accumulation tolerance Fp: 0.090
28, week limit deviation fpt: 0.020
29. Tooth blank tolerance marked on the drawing: The inner hole is in accordance with IT7 level: check the "Standard tolerance table" according to the hole size in the manual.
30. Radial runout of the top circle: check the "standard tolerance table" according to the size of the outside diameter
