When cutting the precision gear, the spiral direction of the hob is reasonably selected, which has a certain influence on the precision of the hobbing precision gear. So how should the hob mounting angle of the precision gear be adjusted? The following is explained in detail by Geer Precision Machinery Co., Ltd.
1. When cutting the teeth, it is hoped that the installation angle of the hob is smaller (the hob spiral is in the same direction as the cut precision gear spiral, and the installation angle is small). Because of this, the hob is divided along the tangential direction of the cut precision gear and the machine tool. The table is turned to the opposite direction, that is, the hobbing machine indexing worm has the opposite axial direction of the worm wheel, which can eliminate the gap of the worm wheel pair and is not easy to cause vibration, thereby improving the cutting accuracy and reducing the surface roughness, and at the same time, the hob can participate in the cutting. More teeth, better cutting conditions, and higher quality of the cut gear.
2. If the mounting angle of the hob is large, the number of teeth participating in the cutting is reduced, the cutting load is concentrated, the teeth are easily worn, vibration is easily generated, and the quality of the cut gear is poor. Therefore, when machining right-hand precision gears, a right-hand hob should be used.
3. When machining left-handed precision gears, a left-handed hob should be used, which can reduce the installation angle of the hob. As for machining spur gears, it is possible to use left or right-hand hobs. Their mounting angle is always equal to its spiral angle, but the steering of the wheel blanks is different when the gears are hobbed.
4. When the standard precision gear is rolled by the standard hob, it is equivalent to the meshing of the rack and the gear. At this time, the center line of the hob tooth is tangent to the circle of the gear. Because the tooth thickness of the gear is deviated, the hob must be generated. A small amount of radial displacement separates the center line of the hob teeth from the gears, which changes the mounting angle of the hob.
5. When using a standard hob to roll and align the precision gear, the hob must be adjusted according to the product of the displacement coefficient specified by the drawing and the gear modulus (actually, the gear tooth thickness is used to control the displacement), which also causes the roller to roll. The change in the mounting angle of the knife. When the hob is blunt and re-grinds the rake face, not only the outer diameter will be reduced, but also the diameter of the pitch circle will be reduced, and the angle of the hob and the mounting angle will also change.