Processing keyways are often used on milling machines. The key connection is widely used. The flat key is the standard part, its two sides are the working surface, to transmit the torque. The connection level key is placed in the keyway of the shaft and shaft parts. The keyway on the shaft is referred to as the shaft groove and machined with the milling machine. The keyway of the wheel part is referred to as the hub groove and machined with broaching machine.
1. The main technical requirements of the shaft groove
Shaft groove is a right angle groove, the technical requirements and the technical requirements of the right angle groove is basically the same. But the two sides of the shaft groove, with the two sides of the flat key match, is the main face, the surface roughness Ra 3.2um, width dimension tolerance level IT9. The depth of the shaft groove, length, groove bottom surface roughness requirements are not high.
2. Milling method of keyway on shaft
Through the slot and circular half of the slot, the general use of disc slot milling cutter. The width of the shaft groove is ensured by the width of the mill cutter, and the radius of the groove bottom of the half-groove is guaranteed by the radius of the milling cutter. The seal on the shaft is bad and the bottom of the groove is a half-slot at right angles. Milling with a keyway cutter and determining the diameter of the keyway cutter by the width dimension of the shaft groove.
(1) The workpiece clamping and correction
To ensure that the workpiece axis groove symmetry, commonly used clamping methods are:
1) With a flat clamp clamp milling shaft groove, processing accuracy is low, generally applicable to single-piece production.
2) With V-shaped block milling groove, milling shaft is the key to the commonly used clamping method. After processing, the symmetry of the shaft groove is higher. For a long axis with a diameter of 20 to 60 mm, the T-groove of the milling machine table can be used and the press plate is pressed and milled.
3) With the dividing head clip. Use the top of the dividing head and the tailstock to clamp the workpiece with a three-pointed self-centering chuck and a tailstock tip. The symmetry of the shaft groove is easy to guarantee.
(2) Adjustment of milling cutter cutting position
In order to ensure the symmetry of the shaft groove, the position of the milling cutter must be adjusted so that the axis of the keyway cutter or the symmetrical plane of the disc slot cutter passes through the axis of the workpiece. Commonly used adjustment methods are:
1) Press the cut knife. The method of precision is not high, but easy to use, is a commonly used method of alignment.
①Disc-shaped slot milling cutter cutting method. The workpiece is roughly adjusted to the symmetrical center position of the disc slot cutter, the milling machine is started, an elliptical cut mark close to the width of the milling cutter is drilled on the surface of the workpiece, and then the milling machine table is moved so that the cutter width falls on the ellipse The middle position; if the oval out of the asymmetry, you need to adjust and then cut.
②Keyway milling cutter cutting method. Keyway milling cutter cutting method and the disc slot cutter cutting method is basically the same, to make the end mill in the middle of the small plane, if the test out of the small plane on both sides of the asymmetry will need to be adjusted and try to cut.
2) Rub the side to adjust the center. This method is very high precision, suitable for disc slot cutter larger diameter or longer keyway cutter occasions.
3) Adjust the center with a leverage dial indicator. This method of high precision, suitable for automatic vertical milling machines used.
How to actually process the keyway on the milling machine, we will continue to introduce in the next blog, welcome attention.