What should you pay attention to when machining gears?
1, curved surface center hole
Since all the machining steps of the gear pump gear are based on the center hole as the position reference, the gear machining accuracy is required to be high, so the quality of the center hole has a great influence on the machining quality of the gear. The contact between the central hole of the curved surface and the tapered surface of the arc is an annular strip contact, the contact is good, the position is accurate, and the center hole is easy to be ground.
2. The depth of the center hole and the distance between the two center holes
General gear pump production is mass production, and all machining processes of pump gears are based on two central holes. In order to simplify the adjustment of the machine tool and make the machining operation convenient, the depth from the center hole of the gear machining to the end face of the journal and the distance between the two center holes should be strictly controlled, and a special inspection tool should be set in the machining process for inspection.
3, the tooth blank
The gears of the medium and high pressure gear pumps are all integral shafts, and the gear blanks are generally die forged. Due to the large machining allowance of forgings, it consumes energy and consumables. At present, some gear processing factories use precision forgings, and the bar with the thickness of the journal size and the margin is used to heat the middle part to the blank size of the gear. It is also possible to use a friction welded part as a tooth blank, which saves energy, reduces material and reduces processing time.
When machining helical gears with a hobbing machine, note that:
1. Adjustment of the exchange gear: speed, indexing, axial feed, differential exchange gear. Pay special attention to the calculation of the differential exchange gear directly affecting the helix angle of the helical gear, which should be accurate to more than 5 decimal places. Idle to confirm the direction of each movement.
2. Hob installation: The hob axis and the workpiece axis meet a certain angle of intersection. The size and direction of the angle of the axis depends on the size and direction of the helix angle of the workpiece and the hob.
3. Centering of the hob: The center of symmetry of a tooth or tooth groove of the hob coincides with the center line of the workpiece to ensure that the tooth profile is symmetrical.
4. After adjustment, the micro-feed (with a cut on the workpiece) can be verified by trial and error.
5. The rest is identical to the spur gear.