Main factors affecting clamping force of spring chuck

Spring chuck is a simple process equipment, but there are many main factors affecting the clamping force. Understanding the basic principles can help the workpiece (or tool) clamp accurately and loosen the loops to find defects. Following are the main factors affecting the clamping force and a summary of the application history.

Axial force. The pull rod exerts an axial tension on the spring chuck
. In the application of spring chuck, the pulling force of axial force can be exerted by different methods, but its principle is the same. Therefore, a large axial tension will produce a large clamping force, and vice versa. In general, the axial tension of the tie rod can be adjusted on the NC machine tool.
In the application of spring chuck, the locking angle viewpoint of the chuck will select the radial clamping force provided by the spring chuck under the same axial tension, which is generally selected by the machine tool manufacturer and spring chuck manufacturer. The selection of locking viewpoints should start from the aspects of economy and reliability, and be determined according to the different types of machine tools (such as lathes), operating conditions (dynamic and static) and uses (workpieces and cutters).
Spring chuck
The conflict force between workpiece (or tool) and spring chuck will directly affect the strength of clamping (but not the size of clamping force). The greater the conflict force, the stronger the clamping of the workpiece, and vice versa. In order to defeat the relative roll or axial movement between the spring chuck and the workpiece (or cutter), various methods can be selected in the manufacturing process of the spring chuck, and then conflicting forces can be carried out, such as intentionally making a saw-tooth shape in the inner hole of the spring chuck or impregnating the carbide micro-grains in the clamping surface, etc.
Conflict between spindle cone and spring chuck at locking angle. The size of the collision force also directly affects the clamping force of the spring chuck on the workpiece. If the clamping force is too small, the relative roll of the workpiece will occur, and if the clamping force is too large, the wear of the spring chuck will be accelerated.
In practice, spring chuck should often be loosened and replaced. For example, it can be used in turning center. When it is loosened, it can spray a layer of smoothing agent on the outer surface of the inner hole of spring chuck. Conditionally, it is very smooth to choose coolant. This can not only wash away debris on spring chuck, but also provide excellent smoothing effect. Punctual application of smooth grease at lock angle of spring chuck can reduce long-term wear and increase clamping force. It can also use other materials with excellent smoothness, including high-quality grease or wax-based materials with EP (limit pressure) characteristics.
Reasonable selection of clamping diameter standard of spring chuck can ensure the maximum clamping force of spring chuck on workpiece, and end the optimal clamping condition, and then ensure the high quality and high precision of mechanical processing. Assuming that the diameter of the inner hole of the spring chuck is too large, when the chuck closes, the workpiece is only clamped by the orifice of the spring chuck, which may constitute a mismatch of the geometrical shape between the outer circle of the workpiece and the inner hole of the spring chuck, thus reducing the clamping force. Assuming that the diameter of the inner hole of the spring chuck is too small, only the inner hole of the chuck needs to be touched by the workpiece when the chuck closes, the clamping force will increase, but it will form a different axis between the chuck and the workpiece. A standard spring chuck can only clamp and locate the workpiece with the corresponding diameter standard. A company specializing in spring chucks recommends that the scope of application of spring chucks be <0.0254 mm.