Clamping is an important part of the workpiece clamping process. After positioning the workpiece must be generated by a certain clamping force, the workpiece pressed on the positioning element, so that it maintains an accurate positioning position, will not be due to cutting force, the workpiece gravity, CNC lathe centrifugal force or inertial force and the like Position changes and vibration to ensure machining accuracy and safe operation. The mechanism that generates the clamping force is called the clamping device.
CNC Milling Machine's Toolings
(A) the basic requirements of the clamping device should have
(1) the clamping process is reliable, does not change the correct position occupied by the workpiece positioning.
(2) the appropriate size of the clamping force, it is necessary to ensure that the workpiece in the processing of its position stable, small vibration, but also to make the workpiece will not produce excessive clamping deformation.
(3) Simple and convenient operation, labor-saving and safe.
(4) good structure, the knotting knot CNC lathe structure and strive to simple, compact, easy to manufacture and repair.
(B) the direction of the clamping force and the choice of the role of points
(1) The clamping force should be towards the main positioning datum. The workpiece is bored and / 4 surface has a verticality requirements, so processing to A surface as the main positioning base surface, the clamping force F, the direction should be / 4 surface. If the clamping force is changed to the B surface, due to the error of the angle between the side of the CNC lathe and the bottom surface B, the positioning position of the workpiece is damaged during clamping, which affects the perpendicularity between the hole and the 4 surface. CNC lathe factory
(2) The point of application of the clamping force shall lie within the bearing area of the positioning element and close to the geometric center of the support element. Clamping force acting on the bearing surface, leading to tilt and movement of the workpiece, destroying the workpiece positioning.
(3) The direction of clamping force should be helpful to reduce the size of clamping force. A hole drilling, clamping force Lu J and axial cutting force F. , The same direction of the workpiece gravity C, the clamping force required for the process is minimal.
(4) The direction of the clamping force and the point of action should be applied to the CNC lathe parts of the rigid direction and better parts. The axial rigidity of the thin-walled sleeve workpiece is better than that of the radial direction, and the clamping force should be applied in the axial direction. When the thin-walled box body is clamped, it should act on the convex edge of the just CNC lathe with good factory property. Without the flange, the single-point clamping can be changed to three-point clamping.
(5) clamping force point should be as close as possible to the workpiece surface. To improve the rigidity of the workpiece processing parts, to prevent or reduce the workpiece vibration, the clamping force should be as close as possible to the processing surface. Fork clamping, the main clamping force F: Vertical acting on the main positioning of the base surface, near the processing surface at the auxiliary support, the application of a suitable auxiliary clamping force a few, can improve the mounting rigidity of the workpiece.
(C) the estimated clamping force size
The size of the clamping force on the reliability of the workpiece installation, workpiece and fixture CNC lathe deformation, the complexity of the clamping mechanism has a great relationship. During processing, the workpiece by the cutting force, centrifugal force, inertial force and the role of the workpiece gravity itself. General CNC lathe factory processing small and medium-sized workpieces, the cutting force (Moment) play a decisive role. When processing heavy and large workpieces, the effect of the gravity of workpieces must be considered. Workpieces under high-speed machining conditions, you can not ignore the centrifugal force or inertia force on the clamping effect. In addition, the cutting force itself is a dynamic load, which also varies during the machining process. The size of the clamping force is also related to the rigidity of the process system and the transmission efficiency of the clamping mechanism. Therefore, the calculation of the clamping force is a very complicated issue, which can only be roughly estimated. For simplicity, when determining the clamping force at low speed, only the influence of cutting force (moment) on the clamping can be considered. It is assumed that the CNC lathe process system is rigid and the cutting process is smooth. According to the process of clamping Tight the most unfavorable instantaneous state, according to the principle of static balance to find the size of the clamping force, and then multiplied by the safety factor as the actual required clamping CNC lathe force, that is
Fj = kF
Where Fj - the actual required clamping force;
F - Under certain conditions, according to the static balance of the calculated clamping force;
K - safety factor, considering the cutting force changes and process system deformation and other factors, generally take A two 1.5-3.
The actual application is not a numerical control lathe CNC lathe factory needs to calculate the clamping force, manual clamping mechanism generally based on experience or analogy to determine the clamping force. If you do need more accurate calculation of clamping force, you can use the above method to calculate the size of the clamping force.
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