Design points for exploring incomplete gear mechanisms
Milling Machine, Ce Top Quality Drilling and Milling Machine (ZAY7032), China Milling Machine Zhenjiang Hangda Equipment Co., Ltd , http://www.chlathe.com
Rb1a, Rb1b, Rb2c, and Rb2d are the base circle radii of a, b, c, and d, respectively. According to the basic parameters of the gear, the angle H1 between the center line of the first gear of the a gear and the center line of the b gear tail can be obtained, and the angle H2 between the center line of the c gear head and the center line of the d gear tail on the driven shaft. The traditional design method combines many factors affecting the pressure angle of the mechanism with the allowable values ​​under the ideal state. The constant value is [A1]=30°, [A2]=70°, which is unscientific, not rigorous and unreasonable.
In the new pressure method, the follower pressure angle is fixed to the same value regardless of the lift or return mechanism. In general engineering, [A]=50°. In order to ensure the continuity and integrity of the movement of the two transmission shafts, the toothed portions of the incomplete gears on each shaft form a full circle in turn, so the drive shaft must satisfy H1 360Z'1a(Z1a-1) H'1 360Z'1b (Z1b-1)=360 slave axis must satisfy H2 360Z'2c(Z2c-1) H'2 360Z'2d(Z2d-1)=360 where: 360Z'1a(Z1a-1) is Z1a tooth corresponding The central angle of the circle, and so on.
Design points: In the design of incomplete gear parameters, first calculate the parameters according to the standard spur gear meshing, and then calculate H1, H2, H'1, H'2, if not satisfied, you can change the master and slave. The tooth height coefficient of the first and last teeth of the moving gear is solved, and the displacement gear can also be used for solving. In the incomplete gear mechanism transmission, the speed is changed, and the degree of coincidence is 1 in the entry and exit of the meshing zone, so the above mechanism can only be used in the case where the speed is not high and the load is not large. Calculation example. The modulus is m=2mm, the height coefficient of the tip is ha=1, the pressure angle is A=20°, Z1a=8, Z′1a=18, Z1b=14, Z′1b=28, Z2c=14, Z′2c= 28, Z2d=8, Z'2d=18. Using CAD drawing, the result can be quickly obtained, that is, H1=28.561°, H2=28.561°H'1=23.412°, H′2=23.412°, the result is substituted. (1) and (2) can not be satisfied, the incomplete gear b, d can be changed to the displacement gear, the displacement coefficient is x1=0.13, x2=-0.13, then H1=29.445°, H2=29.445°H '1=23.412°, H'2=23.412° Thus, the formula (1) and the formula (2) are satisfied.