High-precision And Simple Screw Centering Clamping Device

High-precision and simple screw centering clamping device

Since symmetry is widespread in mechanical parts, the centering clamping device is widely used in machining. The traditional centering and clamping device mainly adopts the structure shown in Figure 1. The two clamping jaws move symmetrically along a straight line to the center under the action of the left and right screw screws to achieve the purpose of centering and clamping the workpiece. Generally, the clamping force of this screw centering clamping device does not coincide with the axis of the left and right screw, which will produce an eccentricity. The two clamping jaws must have linear guides to restrict their movement, which is difficult to manufacture.

　　In production practice, the author explored the screw centering clamping device shown in Figure 2 that uses the rotary motion of the articulated shaft instead of the linear motion of the guide rail. Its characteristic is that it is very easy to manufacture. It is precisely because of this feature that the accuracy of the fixture is easy to guarantee, and it can fully achieve the accuracy of the traditional screw centering clamping device, which is introduced as follows.

　　The functions of each part are as follows: The swing arm transfers the clamping force of the left and right screw to the lever of the workpiece; the clamp is the basis for the installation of all parts; the centering adjustment nut is used to adjust the position of the left and right screw and the clamp, thereby To achieve the purpose of adjusting the centering position, after the adjustment, the locking screw on it can be locked and fixed with the left and right screw. The two left and right centering adjustment nuts are matched with the clamp to limit the axis direction of the left and right screw. The degree of freedom; the swingable nut cooperates with the left and right screw to produce clamping force, and the influence of the angle change when the swing arm is opened can be eliminated by swinging. This is an ingenuity of the centering fixture; the left and right screw are all screws The necessary components of the centering clamping mechanism, the thread lead directly affects the centering accuracy; the swing arm of the swing arm rotating shaft is connected with the clamp and rotates around the connecting shaft; the floating claw increases the clamping point of the workpiece, if the floating claw is not used At this time, the rotating shaft of the floating claw can be enlarged, and a pair of centering clamping points can also be formed. In addition, during the centering and clamping of the swing arm shaft, the clamping force is pressed against the main mounting surface of the workpiece, which is very beneficial to the clamping of the workpiece. To express the internal structure, a swing arm was removed as shown in Figure 2. Figure 3 shows a cross-sectional view of the centering jig. The structure, working principle and manufacturing points of the jig can be better understood by cooperating with that shown in Figure 2.

　　Obviously, this kind of centering fixture adopts a swing arm and a swing arm rotating shaft, instead of the guide rail structure of the traditional spiral centering clamping device, and the rotating shaft replaces the guide rail, and the structure is simpler. Especially when making 4 swing arms, as long as the finished parts are stacked together to process the 3 holes on them, it can be ensured that the 3 mounting holes of the 4 swing arms are very similar in size, even if they are on the design drawings. The position of the 3 holes has a large error and does not affect the accuracy of the fixture. That is to say, the production of the swing arm of the centering fixture does not require advanced machine tools such as coordinate boring, as long as the ordinary drilling machine is used through drilling and reaming processes. Then a high-precision centering fixture can be produced.