Depending on the angle of the taper shank, the commonly used fixed tip can be divided into a Morse taper shank and a special taper taper shank. For the grinding workshop of the Morse taper shank, there is a special tooling, which will not be introduced here. The special taper taper shank has a fixed tip and high machining accuracy and complexity. The use of a reasonable process is conducive to improving the machining accuracy of the special taper fixed tip.
The following is an example of a special taper top machining process with a machining head CA 8480 lathe fixed tip (see photo) on the M 131W.
1. Determine the processing sequence
As can be seen from the figure, the size to be ground is a taper shank with a diameter of 7 9.5 mm, a tapered taper of 1:7, and a taper tip with a diameter of 100 mm and a taper of 60°. Moreover, the conical surface of the taper tip facing the 1:7 concentricity is 0.015 mm. According to the selection principle of the rough reference, the processing of the 1:7 taper should be the axis of the workpiece, that is, the left end of the workpiece and the 60° top surface. As a rough reference (60° top surface for coarse reference to ensure machining allowance of 60° top surface). According to the principle of selection of fine reference, the taper length of 1:7 is longer than 60° cone tip, 60° cone tip processing should be Use a 1:7 cone as the fine reference. Therefore, the processing sequence is to first process a 1:7 taper surface and then process the 60° top surface.
2. Fixing method
The 1:7 taper is machined with two top clips. One is the top of the carbide and the other is the counter top of the ordinary material. However, since the 1:7 taper cannot be directly clamped, it is necessary to solve the problem of the workpiece clamping by completing the grinding of the 60° top surface. The clamping is performed by appropriately lengthening the shank cylindrical table as a process table. After the 60° taper is finished, the lengthened part is removed, so that the clamping is firm and the precision is high after processing.
3. Conical grinding
External Conical Surface Grinding According to the size of the cone and the shape of the workpiece, the following three grinding methods can be used: Rotate the table to grind the cone, rotate the head frame to grind the outer conical surface and rotate the wheel holder to grind the outer conical surface. Here, the grinding process with a taper taper of 1:7 uses a rotary table method. The angle of the taper shank can be matched with the roll lathe sleeve, and the large end is in contact with more than 80% of the contact surface. The angle error can be adjusted to the workbench and removed after repeated iterations and grinding.
60° working cone surface processing, through the four-jaw single-action chuck clamping the taper shank part, rotating the head frame and the grinding wheel frame each 15°, the grinding method of the working cone surface can be realized by combination. The working cone angle can be measured by the light transmission method using the vernier universal angle ruler. The angle error can be adjusted by rotating the table and after multiple test cuts and measurements.
The following details should be noted during the machining process to ensure the two-cone coaxiality:
(1) Grinding and aligning the circle at a diameter of 100m, and using the four-jaw single-action chuck to find the right time.
(2) When finding the taper shank to grind the working cone, find two points, one of which is close to the chuck jaw and the other point is 1 00 mm in diameter. Both errors should be controlled within 0.01 mm.
(3) When the four-jaw single-action chuck is being aligned, the distance to be corrected should be as short as possible.
If the machining position is far from the chuck jaws, the error after machining is easily amplified, and in serious cases, the coaxiality may be excessive.
4. Precautions during processing
(1) Grease should be added when the two top clamps are clamped, and the rotation speed should not be too high to avoid burning the top.
(2) The cutting fluid should be sufficient for grinding.
(3) To rotate the wheel frame during grinding, the wheel must be trimmed before.
(4) When grinding the working cone of 60°, the busbar on the side of the working cone is not parallel to the guide rail of the table. Therefore, when the working cone is ground, it cannot be moved by hand. Pay attention to safety when moving the table to the knife. Be careful not to injure the workpiece with the grinding wheel to prevent accidents.
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