Common defects and solutions of gear hobbing in th

2022-07-23
  • Detail

Common defects in gear hobbing and their solutions

the hob tooth profile error is too large or the gear splitting is incompetent, and the instantaneous speed changes greatly. There are four types of workpiece defects

(1) after the hob edge is ground, Poor equipartition of cutter teeth

Yicheng Xinneng invests in the production of 10000 tons of carbon graphite cathode materials

(2) large axial movement of hob

(3) large radial runout of hob

(4) blunt hob

main methods: focus on the grinding quality of hob blade, the installation accuracy of hob and the geometric accuracy of machine tool spindle:

(1) control the grinding quality of hob blade

(2) ensure the installation accuracy of hob, At the same time, do not knock when installing the hob; The gasket end face is flat; The end face of the nut shall be vertical; The inside of the taper hole shall be clean; After the bracket is installed, there shall be no clearance

(3) recheck the rotation accuracy of the machine tool spindle, repair and adjust the hob spindle bearing, especially the thrust washer

(4) replace the new tool

2) check the axial movement of the indexing worm of the machine tool workbench, And the adjustment and repair

3) check the installation and operation of the straddle wheel and the split tooth exchange gear

4) adjust the plug iron of the tool holder slide plate

5) reasonably select the correct scheme for workpiece clamping

4) the fixture positioning end face is not perpendicular to the rotation center line of the workbench

5) workpiece clamping components, For example, the accuracy of washers and caps is not enough

(2) in terms of workpiece:

1) the diameter of workpiece positioning hole is out of tolerance

2) when the workpiece is installed by aligning the outer circle of the workpiece, the coaxiality of the outer circle and the inner hole is out of tolerance

3) the workpiece clamping rigidity is poor

the vertical feed direction of the hob is too inclined to the axis direction of the inner hole of the gear blank. When processing helical gears, there are also incorrect additional movements

(1) in terms of machine tools and fixtures:

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

2) the end face runout of the workbench is large

3) different axes of the upper and lower centers

4) the meshing clearance of the indexing worm gear pair is large

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

6) the pitch error of the vertical feed screw is large

7) gear splitting,the The differential exchange gear has large error

(2) related to workpiece

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

2) the positioning hole of the workpiece is not perpendicular to the end face

in order to control the geometric accuracy of the machine tool and the correct installation of the workpiece, the following article 4) 5) 6) 7) is mainly applicable to the processing of helical gears

(1) related to machine tool and fixture:

1) repair the column accuracy, Control the thermal deformation of the machine tool

2) repair the rotation accuracy of the workbench

3) repair the accuracy of the column or the upper and lower ejector pins after repair

4) reasonably adjust the meshing clearance of the indexing worm gear pair

5) repair the part accuracy of the indexing worm gear pair

6) if the accuracy of the vertical feed screw is not reached due to wear and tear, it should be replaced in time

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

(2) the workpiece should be controlled

1) the parallelism error of the two end faces of the gear blank should be controlled

2) the perpendicularity between the positioning hole and the end face of the gear blank should be controlled

focusing on the accuracy of the gear splitting kinematic chain, Especially for the indexing worm gear pair and hob:

1) repair the transmission accuracy of the indexing worm gear pair

2) repair the rotation of the worktable do you know the working mode of the torsion testing machine? Accuracy

3) check the meshing tightness and operation of the dividing exchange gear

1) control the material quality of the gear blank

2) correctly select the heat treatment method, especially the hardness after quenching and tempering, It is recommended to adopt normalizing treatment

3) correctly select the cutting amount to avoid chip buildup

4) correctly select the cutting fluid, especially pay attention to its lubrication performance

5) replace the new cutter

due to sudden changes in the mutual position between the hob and the gear blank:

1) the triangular guide rail of the column is too loose, resulting in sudden changes in the feed of the hob, and the triangular guide rail of the column is too tight, Cause creeping phenomenon

2) the meshing clearance of the helical gear of the tool rest is large

3) the oil pressure is unstable

2) if the tool rest is worn due to long service time, it should be replaced

well known

3) properly maintain the machine tool, especially clean, so that the oil circuit remains unblocked: the oil pressure remains stable

1) overhaul the machine tool with serious wear due to long service time

2) improve the clamping rigidity of the hob, such as reducing the distance between supports; The hob with handle shall be of large shaft diameter as far as possible. Improve the clamping rigidity of the workpiece: for example, increase the support end face as much as possible, and the support end face (including the workpiece) is only concave; Shorten the distance between the upper and lower ejector pins

3) correctly select cutting parameters

4) correctly install the rear bracket

Copyright © 2011 JIN SHI