The enveloping hourglass worm with variable tooth thickness involute gear is a new type of worm. At present, there is no project inspection standard. Due to the inconsistency of left and right tooth surfaces and the different tooth shape, tooth thickness and lead, the existing accuracy standards and inspection methods of involute gear and cylindrical worm can not be used for the inspection of hourglass worm. According to the detection standard and method of, the meshed data points of the hourglass worm tooth surface are collected, and the difference between the actual value and the theoretical value of the tooth surface is shown in the form of topology, as shown in Figure 1.
The solid line in the figure is the measured data grid of tooth surface, the dotted line is the theoretical data grid, and the distance between the measured data points and the theoretical data points Δ FIJ is the deviation value at this point, the subscript I is the i-th helix in the direction of tooth profile, and the subscript j is the j-th tooth profile in the direction of tooth profile. When the actual tooth surface is within the theoretical tooth surface, the deviation is small Δ FIJ is negative, as shown by the blue line in the figure; When the actual tooth surface is outside of the theoretical tooth surface, the deviation is small Δ FIJ is positive, as shown in the red line.
Pass the maximum deviation value Δ Fmax and mean deviation Δ f Σ The calculation principle of tooth surface accuracy is as follows: