If used for a long time, if the spring chuck wears more than a certain limit, the workpiece will not be firmly clamped, which directly affects the machining accuracy and production efficiency. At this time, the spring chuck is scrapped, which virtually increases the manufacturing cost of the fixture, resulting in a huge economy loss. To improve the wear resistance of the chuck, it is necessary to increase the hardness of the chuck. If the hardness of the chuck is too high, the elasticity of the chuck is weakened and the spring flap is easy to break. For this problem, an insert spring chuck is designed.
Improvement of spring chuck
It is composed of two parts, one is the chuck body, and the other is the clamping block, and the two are connected by screws. The chuck body has six spring flaps, and the clamping and unclamping actions are completed by the elastic deformation of the spring flaps when working. The material of the chuck body is 65M n, and the quenching hardness is 40～45 HRC to ensure the elasticity of the chuck; The block is installed on the claw of the chuck and directly contacts the workpiece. The block is an easy-to-wear part. The material of the block can be GCr15 with a quenching hardness of 60-62 HRC to increase wear resistance. The following problems have occurred in the use of insert spring chucks:
(1) Since the chuck manufacturing error is prone to eccentricity, the wall thickness difference of the ferrule after turning will be out of tolerance.
(2) After the clamping block is arbitrarily installed in the chuck, the roundness of the clamping block is not good. If the ferrule is clamped with such a clamping block, the wall thickness difference of the processed ferrule will also be out of tolerance. It must be overcome when manufacturing.
For the conical surface of the fine turning chuck, threaded tires are used to ensure the machining accuracy of the chuck body. After finishing each surface of the chuck and drilling the equally divided holes, turn the conical surface again. When turning the conical surface, use the threaded surface as the positioning reference. Design a threaded tire, which can ensure the machining accuracy when turning the conical surface. The processing principle is as shown in the figure below. First, screw the chuck onto the threaded tire, then install the threaded tire on the spindle of the machine tool, and finally use the small tool holder on the pallet to cut.
Grinding the tapered surface of the chuck: When grinding the tapered surface of the chuck, threaded tires are also used to ensure the grinding accuracy. The cone surface is an important positioning surface in the clamping process of the chuck. The accuracy of the cone surface is good or bad, which directly affects the accuracy of the entire chuck.
To design a set of threaded tire clamping chucks for grinding, the threaded surface is still selected as the positioning reference. The grinding principle is as shown in the figure below. After grinding, the conical surface can reach a coaxiality of 0.1mm with respect to the threaded surface.
Grinding the inner diameter of the collet chuck: The inner diameter of the chuck is ground to ensure the accuracy of the grinding process. The inner diameter of the chuck is also a positioning surface. The inner diameter of the chuck is used to clamp the clamp, and the clamp is used to clamp the workpiece, so the accuracy of the inner diameter is also direct Affect the accuracy of the workpiece, which requires that the inner diameter and the conical surface must be coaxial. We design a special grinding inner diameter mold clamping chuck. This tire is positioned on a conical surface. The grinding principle is shown in the figure below. 02mm。 After grinding, the inner diameter of the chuck is generally up to 0.02mm with respect to the concentricity of the conical surface. The head of the chuck is cut into six petals, and then tempered to enlarge
Using this solution to manufacture the spring chuck can greatly reduce the manufacturing cost and the difficulty of processing, reduce unnecessary waste of materials, improve production efficiency, and bring huge economic benefits.