The main factors affecting the clamping force of the collet

The spring chuck seems to be a simple process device, but there are many main factors that affect the clamping force.
The main factors affecting the clamping force of the collet and summary:

1. Axial force. As shown in the figure, the axial pulling force exerted by the pull rod on the collet. In the use of the spring chuck, the axial force can be applied in different ways, but the principle of action is basically the same. Obviously, a large axial tension will produce a large clamping force, and vice versa. Generally, the axial tension of the tie rod can be adjusted by the operator.

2. In the use of the collet chuck, the designed locking angle (or head inclination) will determine the index that the clamping force can reach after expansion, which is usually determined by the machine tool manufacturer and the collet manufacturer. When the new design of the spring chuck is still being explored, the designer recommends that the user use the existing spring chuck structure in consideration of economy and reliability. The standard taper (or head inclination) has been determined by the design according to the type of machine tool (such as lathe, etc.), use conditions (dynamic and static) and purpose (workpiece and tool).

3. The total friction between the workpiece (or tool) and the collet will directly affect the clamping force. A small friction value will result in a small clamping force and vice versa. The collet chuck supplier can take various measures to overcome the relative rotation or axial movement between the collet chuck and the workpiece (or tool). For example, the inner hole of the collet chuck deliberately creates a serrated shape or micro-hard alloy Die is immersed in the clamping surface etc.

4. The conical surface of the spindle and the collet chuck friction at the locking angle. The friction force also directly affects the clamping force of the collet on the workpiece. If the friction force is too small, the clamping force is not enough. Too much clamping force will accelerate the wear of the spring chuck. During use, the collet chuck should be loosened frequently to exchange workpieces. For example, when it is used on a turning machining center, a thin layer of lubricant should be sprayed on the surface of the inner hole of the collet chuck when loosened. Conditional use of coolant is better for lubrication, because the coolant provides a flushable collet, and the lubrication effect is good. In particular, regular application of coolant to the locking angle can reduce long-term wear and increase clamping force. Some more materials with better lubricating effect can also be used, including high-quality grease or wax-based materials with EP (Extreme Pressure) characteristics. It seems a little strange that some smart operators have great difficulty in processing and when the general cooling and lubricating effect is not good, they choose the lipstick used by ladies, which is said to be effective.