When the length of the cutting cone is greater than the working length of the small slide plate and the conic degree is smaller, the offset tailstock method can be used. When turning the lathe, the workpiece is clamped by the center, and the tailstock is laterally shifted inward by a distance s, so that the workpiece rotation center and the longitudinal feed direction intersect to form a conical half angle a/2, so that when the turning tool is longitudinally fed, the A conical surface is formed on the surface of the workpiece.
(1) Calculation of Tailstock Offset When using the offset tailstock method to turn a workpiece that is partially conical, the overall offset of the workpiece is caused by the offset of the tailstock. Therefore, when calculating the offset S of the tailstock , the total length of the workpiece k is an important parameter, and the cone length ￡ only plays a role in determining the half angle of the cone a/2.
(2) The method of offsetting the tailstock According to the calculated offset S of the tailstock, move the upper part of the tailstock, usually offset the upper part of the tailstock inward, so that the small end of the cone is on the side of the tailstock, which is beneficial to operation and measurement. Common methods of offsetting the tailstock are:
1) Control the offset with the dial on the tailstock. Loosen the lock nut of the tailstock first, then use the Allen wrench to turn the adjusting screws l and 2 on both sides, so that the screw l retreats, the screw 2 advances, and the upper layer of the tailstock moves inward by a distance S according to the illegal scale. Then tighten the adjusting screw and tailstock locknut. This method of lathe is easy to operate and can be used when the accuracy of the taper angle is not high.
2) Use the middle slide scale or dial indicator to control the offset. After clamping the workpiece with the two centers, clamp a copper block on the tool holder, so that the front end of the copper block is in light contact with the outer circle of the workpiece head, write down the scale number of the middle slide plate, move back, and swing forward again until the tailstock is offset. Stop when the number of ticks of the quantity S is reached. Then offset the upper part of the tailstock until the outer surface of the workpiece lightly touches the copper block.
When the accuracy of the cone angle is high, the difference in the reading of the dial indicator can be used to control the offset of the tailstock. The dial indicator probe is in vertical contact with the outer circle of the workpiece head in the horizontal plane passing through the axis of the workpiece, and then offsets the tailstock, so that the indicator pointer of the dial indicator turns to the position of the offset S of the tailstock, and then the tailstock is fixed.