Usually, in well-known gear measuring centers (such as Klingenberg, Wenzel), microscopic measurements of gear surfaces can be carried out.
1. Common methods of microscopic inspection of gear surfaces
1) Profile of tooth shape and tooth direction. Wire detection.
Traditional gear quality inspection can only be used to analyze defects related to low-order harmonics.
2) Fourier detection of tooth surface FFT.
Fast Fourier Transform (FFT) is used to consider high and low order harmonic data, and correlate the detection results with noise analysis, which is suitable for high-performance analysis of sound quality. the surface of the gear teeth.
The impact of low order amplitudes on noise is very small. The first order corresponds to the eccentricity of the gear and the second order corresponds to the elliptical movement of the gear. Therefore, the lower order spectrum is usually filtered and only the high order one. the spectrum is taken into account.
If a large amplitude occurs in the meshing order and frequency doubling order of the gear pair, it is due to poor gear integration, which is caused by the large impact of the gear pair gears during incoming and outgoing meshing. Large amplitudes are produced at non-integer multiple orders, i.e. “phantom orders” are produced, which are caused by poor undulation of the tooth surface.
3) Topology detection Topography.
The three-dimensional morphology of the surface microstructure of a single tooth is shown in the figure. The gears were measured using the Klingelberg P65 gear measuring machine. In the figure: the black line is the mesh line of the tooth surface and the angle is βb; the red line is the trend line of the ripple and the angle is βw;
The smaller the angle between the contact line and the ripple line of the driving surface, the greater the probability of generating noise during the gear meshing process, the driving surface will enter regularly in contact with the valleys and crests of the tooth surface undulation, thereby causing undulation of the tooth surface. impact and thus generating noise. The three-dimensional topography when βw = βb is as shown in the figure. When the ripple line and the contact line are parallel, the probability of generating noise is greatest.
2. Powerful gear sharpening process
Electric sharpening is the finishing process of removing a certain margin from the gear surface after heat treatment of the gear. It has the method of forced modification of the tooth surface and is carried out by dressing the dressing wheel, workpiece axis and sharpening wheel. The axes perform complex movements. The structural diagram of the powerful PRAWEMA gear honing machine and the position relationship between the workpiece and the grinding wheel are as shown in the figure. 
How to change the direction of gear surface waviness during gear sharpening process. According to the gear topology inspection report, focus on several parameters. The NVH on the upper side is better than that on the lower side because the smaller the angle βw, the lower the probability of generating a resonant frequency. Based on this theory, in the process of gear grinding, how to reduce the angle βw is the direction to optimize the NVH.
Redraw the helix angle of the sharpening wheel and readjust the axis intersection angle. The original parameters and the optimized parameters are shown in the table.
β w=-25.4° left; β w=-23.7° right. According to the correlation between topology and NVH test results, both left and right sides are detrimental to NVH and βw should be controlled. .
The reprocessed topology report is shown in the figure. It appears from the report that the angles β w = 0.4° on the left and β w = 0.0° on the right are basically optimized in theory.
Subsequent NVH test results on the whole machine showed that under the same conditions, the NVH was also 5-10 dB lower than before optimization.
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