1 ring gear runout (ie geometric eccentricity)
Ring gear runout refers to a transfer within the probe within the alveolar or teeth on the high school sided with the tooth contact probe relative to the tooth axis of maximum variation. Ring gear is eccentric with respect to the shaft centerline, this is due to the eccentric mounting parts, the part of the center hole and two rotational center of the table coincides or is not installed and cause too much deviation. Or because of poor manufacturing top and top hole, caused by poor surface contact with the positioning eccentric, so jump ring gear diameter above the main cause analysis should be addressed.
2 normal length errors (ie sports eccentric)
Hobbing principle is generating method of machining gears, gear blanks from the tool to the drive chain between the sub-toothed gear ratio according to a certain relationship to maintain the accuracy of movement. But the drive chain is a series of components of the transmission.
Their manufacture and assembly errors in the transmission of movement is bound to focus reflected to the drive end of the chain parts, the relative movement of the unevenness affect tooth machining accuracy. Normal length change is a reflection of the uneven distribution of the gear teeth, the maximum error, this error is mainly rotary precision worm gear hobbing machine table caused by uneven, there is a circular rail wear hobbing table, and the table indexing worm circular guide different axes caused Furthermore hanging tooth surfaces of teeth with severe bump or hang wheel bite too loose or too tight will also affect the normal line change tolerance.
3 toothed error analysis
Tooth profile error refers to the working part, the inclusion of two actual tooth profile ideal tooth (involute) profile between the normal distances. In the actual processing is impossible to obtain exactly the right involute profile, there is always a variety of errors, thus affecting the smooth transmission. Base circle of the gear involute is to determine the only parameter, if the base circle when hobbing produce errors, tooth inevitably there will be errors. Base circle radius R =
Hob speed / rotary table angular xcosao (ao for the hob original profile angle), the hobbing process depends mainly on the involute hob and gear blank to maintain a certain ratio between the teeth to ensure that the sub- This shows that the error is mainly hob tooth profile error of the decision, hob sharpening poor quality is prone to tooth profile error. Meanwhile hob in the installation resulting runout, axial movement (ie installation error) also affect the profile errors. Common errors asymmetric tooth, tooth angle error (addendum become fat or thickening), resulting in periodic errors.
4 tooth error analysis
Tooth error is indexing cylindrical surface, the whole tooth width range, inclusive actual tooth to tooth design lines two lines end distance. Causing the error is mainly due to tooth machine, tool feed direction and the vertical axis are offset part or on the tailstock center is inconsistent with the rotary table center, as well as helical gear hobbing, hanging round the differential calculation error large, the differential gear manufacturing and transmission chain adjustment error is too large. Another fixture and gear blanks manufacturing, installation, adjustment can also cause teeth to low precision error.
5 tooth surface roughness analysis
Bad tooth surface roughness generally has several phenomena: Hairline, gnawing teeth, fish phosphorus, tear.
Tooth surface roughness caused by poor mainly the following aspects: machine, tool, workpiece overall system less rigid, large gap; hob and the workpiece relative position changes; hob sharpening improper parts uneven material; cutting parameters chosen not appropriate and so on.
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