A brief introduction to chuck clamping

　One clamp and one top clamp

　　When turning general shaft workpieces, especially heavier workpieces, one end of the workpiece can be clamped with a three-jaw self-centering or four-jaw single-acting chuck, and the other end can be supported with a rear center tip, as shown in Figure 2-11. This method is called one-clamp top clamping. In order to prevent

　　Due to the axial displacement of the workpiece due to the action of the feed force, a limit support can be installed in the tapered hole at the front end of the spindle, as shown in the figure. The workpiece steps can also be used for position limiting, as shown in the figure. This method of clamping is safer and more reliable and can withstand larger feed forces, so it is widely used. This method is best used when turning shaft workpieces.

　　When using the rear center to install the support workpiece, you must first drill a center hole on the end face of the workpiece.

　　The center hole is the positioning reference for the finishing of shaft workpieces (such as finishing turning and grinding), and has a great influence on the processing quality of the workpiece. If the roundness of the central hole is poor, the roundness of the processed workpiece will be poor, the cone surface of the central hole will be rough, and the surface roughness of the workpiece will also be large. Therefore, the center hole must be round, the surface roughness of the tapered hole must be small, the angle must be correct, and the center holes at both ends must be coaxial. For the center hole with higher requirements, it also needs to be finely trimmed or ground.

　　The center hole is drilled using a center drill. Commonly used center drills are made of high-speed steel, as shown in Figure 2-12. Center holes with a diameter of less than 6.3mm are usually drilled directly with an integral center drill. The center hole with a larger diameter is usually processed with a corresponding drill bit and a round-shaped inscription drill. The center drill can be clamped by a drill chuck, and then directly or transitionally inserted into the tapered hole of the tailstock sleeve of the lathe using a tapered sleeve.