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Ningbo Tongren Bearing Co., Ltd.
18
2023
-
05
How to identify the quality of non-standard bearing shafts and gears
Analysis of hobbing machining accuracy. The accuracy of the shaft teeth is primarily related to motion accuracy, stability accuracy, and contact accuracy. Hobbing machining uses control of the common normal line length and tooth circle jump to ensure motion accuracy; it uses control of tooth profile error and base pitch error to ensure operational stability accuracy; and it uses control of tooth direction error to ensure contact accuracy. Below is an analysis of several common errors that occur in hobbing machining:
Tooth circle radial runout error. Tooth circle radial runout refers to the maximum variation of the probe relative to the tooth axis within one revolution of the gear; the probe is in contact with both sides of the tooth center in the tooth groove or on the tooth. It is also the deviation of the tooth circle relative to the axis center line; this deviation is caused by the misalignment or excessive error between the two center holes of the workpiece and the rotary center device of the machine table during installation. Or it is caused by poor manufacture of the top and top holes, resulting in poor contact of the locating surface and causing deviation; therefore, the tooth circle jump should be analyzed and addressed from the above reasons.
On a general hobbing machine, using a general-precision hob, only grade 8 precision teeth can be machined. The gear teeth of the transmission shaft require grade 7-8 precision; and during hobbing machining, the two center holes and the end face are mainly used as positioning datum; therefore, analyzing the source of hobbing errors and mastering the methods to ensure and improve machining accuracy are very important.
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