Gear defect – tooth direction error out of tolerance

Main cause

The deviation between the vertical feed direction of hob and the axis direction of inner hole of gear blank is too large. When machining helical gears, there is also incorrect additional movement

(1) For machine tools and fixtures:

1) The triangular guide rail of the column is not parallel to the axis of the workbench

2) Large end runout of worktable

3) Different axes of top and bottom centers

4) Large meshing clearance of indexing worm gear pair

5) There is periodic error in the transmission of indexing worm gear pair

6) Large pitch error of vertical feed screw

7) Large error in gear splitting and differential exchange gear

(2) Related parts

1) The two ends of the gear blank are not parallel

2) Workpiece positioning hole is not perpendicular to the end face


In order to control the geometric accuracy of machine tools and the correct installation of workpieces, the following article 4) 5) 6) 7) is mainly applicable to the machining of helical gears

(1) For machine tools and fixtures:

1) Repair the accuracy of column and control the thermal deformation of machine tool

2) Repair the rotary accuracy of the worktable

3) Repair the accuracy of rear column or upper and lower thimbles

4) Reasonable adjustment of meshing clearance of indexing worm gear pair

5) Repair the part precision of indexing worm gear pair.

6) If the accuracy of the vertical feed lead screw cannot reach the time limit due to wear, it shall be replaced in time

7) The calculation error of differential exchange gear should be controlled

(2) Related parts

1) Control the parallelism error of two end faces of gear blank

2) Control the perpendicularity of the locating hole and the end face of the gear blank