Three Tips for CNC Lathe Workpiece Clamping

Clamping is an important part of the workpiece clamping process. After positioning the workpiece, the clamping force must be generated by a certain mechanism, and the workpiece is pressed against the positioning element to maintain an accurate positioning position, which will not be caused by the effects of cutting force, workpiece gravity, CNC lathe centrifugal force, or inertial force. Position changes and vibrations to ensure machining accuracy and safe operation. This mechanism that generates a clamping force is called a clamping device. (1) Basic requirements for the clamping device (1) The clamping process is reliable and does not change the correct position occupied by the workpiece after positioning. (2) The size of the clamping force is appropriate. It is necessary to ensure that the position of the workpiece is stable and the vibration is small during the processing, and that the workpiece does not cause excessive clamping deformation. (3) The operation is simple, convenient, labor-saving and safe. (4) The structure is good, and the structure of the clamping device of the CNC lathe factory strives to be simple, compact, and easy to manufacture and maintain. (2) Choice of clamping force direction and action point (1) The clamping force should be oriented toward the main positioning reference. The workpiece to be bored has a perpendicularity requirement to the / 4 surface, so the A surface is the main positioning base surface during processing, and the direction of the clamping force F should face the / 4 surface. If the clamping force is changed to the B surface, due to the angle error between the side of the CNC lathe and the bottom surface of the 4 and the bottom surface B, the positioning position of the workpiece during clamping is destroyed, affecting the perpendicularity requirements of the hole and the 4 surface. CNC lathe factory (2) The action point of the clamping force should fall within the support range of the positioning element and be close to the geometric center of the support element. The clamping force acts outside the bearing surface, causing the workpiece to tilt and move, which destroys the positioning of the workpiece. (3) The direction of the clamping force should be conducive to reducing the magnitude of the clamping force. When drilling hole A, the clamping force reed J and the axial cutting force F. The direction of the gravity C of the workpiece is the same, and the clamping force required for the machining process is the smallest. (4) The direction and action point of the clamping force shall be applied to the direction and location where the rigidity of the CNC lathe is relatively rigid. The axial rigidity of the thin-walled sleeve workpiece is better than the radial attachment. The clamping force should be applied in the axial direction. When the thin-walled box is clamped, it should act on the convex flange of the CNC lathe. When there is no flange, you can change from single-point clamping to three-point clamping. (5) The application point of clamping force should be as close as possible to the surface of the workpiece. In order to improve the rigidity of the workpiece processing part and prevent or reduce the vibration of the workpiece, the action point of the clamping force should be as close to the processing surface as possible. When clamping the fork, the main clamping force F: vertically acts on the main positioning base surface, and an auxiliary support is set near the processing surface. When an appropriate auxiliary clamping force is applied, the installation rigidity of the workpiece can be improved. (3) Estimation of the clamping force The clamping force has a lot to do with the reliability of workpiece installation, the deformation of the workpiece and fixture CNC lathe, and the complexity of the clamping mechanism. During processing, the workpiece is affected by cutting force, centrifugal force, inertial force, and the gravity of the workpiece itself. Generally, when machining small and medium-sized workpieces in a CNC lathe factory, the cutting force (moment) plays a decisive role. When processing heavy and large workpieces, the effect of workpiece gravity must be considered. When the workpiece is processed under high-speed motion, the influence of centrifugal or inertial forces on the clamping action cannot be ignored. In addition, the cutting force itself is a dynamic load that also changes during processing. The size of the clamping force is also related to the stiffness of the process system and the transmission efficiency of the clamping mechanism. Therefore, the calculation of the clamping force is a very complicated problem, and generally only a rough estimation can be made. For the sake of simplicity, when determining the clamping force at low speed, only the influence of cutting force (moment) on clamping can be considered, and it is assumed that the CNC lathe process system is rigid and the cutting process is stable. For the most unfavorable instantaneous state, determine the clamping force according to the principle of static balance, and then multiply it by the safety factor as the actual clamping CNC lathe factory force. That is, Fj = kF. Tightening force; F——Clamping force calculated according to static equilibrium under certain conditions; k——Safety factor, taking into account factors such as changes in cutting force and deformation of the process system, generally taking A 2.1.5-3 In practical applications, not all CNC lathes need to calculate the clamping force in the case of a CNC lathe factory. The manual clamping mechanism generally determines the clamping force based on experience or analogy. If you really need to calculate the clamping force more accurately, you can use the above method to calculate the magnitude of the clamping force.