(l) General steps for turning the outer circle of the lathe 1) Align and clamp the workpiece according to the technical requirements.
(2) The turning tool required for the correct clamping process.
(3) Adjust the feed amount. Adjust the handle of the feed box to the proper position according to the selected feed amount.
(4) After adjusting the rotation speed of the lathe according to the selected cutting speed, pull the chuck by hand and see that the transmission is normal before driving.
(5) Adjust the amount of back knife. First, measure the diameter of the surface to be machined, and determine the number of feeds and the amount of back cutting each time according to the machining allowance. When renting a car, test turning is usually used to control the amount of knife cutting. The operation steps of the lathe trial cutting are shown in Figure 64.
①Start the lathe, move the saddle and the middle slide, make the tool tip of the turning tool touch the surface to be machined lightly, and make a shallow mark to determine the starting position of the amount of cutting tool.
② Move the saddle, withdraw the turning tool, and turn the middle slide dial to align with the zero position.
③According to the selected knife amount, use the dial value to control the knife amount a.... When the handle of the skateboard is shaken to the number of grids that is close to the required amount of knife, the lathe should slowly shake or tap the handle lightly to prevent rash advance.
④ Move the saddle to cut the outer circle, and the trial cutting length is about 2mm.
⑤Exit the turning tool of the lathe and measure the diameter of the trial cutting.
⑥According to the measurement size, adjust the amount of the knife on the back. At this time, the lathe can close the feed handle and use motorized feed.
When finishing turning, when the machining allowance is very small, the following method can be used to determine the starting position of the back cut amount, that is, a thin piece of paper is placed between the surface to be machined and the cutting edge of the turning tool, so that the middle slide plate can be moved slowly. feed. When the cutting edge of the lathe is in contact with the sheet of paper and clamped lightly until the sheet of paper cannot be pulled, adjust the scale of the middle slide to zero, which is the starting position of the back-feeding amount, as shown in Figure 6-5.
Problems that should be paid attention to 1) Due to the assembly gap between the traverse screw and the nut during transmission, when the handle is reversely shaken, the idle stroke phenomenon that the dial rotates but the tool holder does not move will occur. Therefore, when using the dial to feed the tool, if you accidentally roll in a few more grids, you can't simply return the number of grids that you advanced, but you should go back a little more in the opposite direction. After returning to all the empty strokes, Then shake the dial to the desired position.
During cutting, since the workpiece is in a rotating state, the cutting amount of the turning tool on the outer circle is twice the amount of the back cutting tool when the sliding plate dial feeds the tool. Therefore, when the machining allowance of the outer circle of the workpiece is determined, the amount of back cutting controlled by the middle slide dial is 1/2 of the machining allowance.