The use technique of three jaw chuck of nc lathe
Three - jaw automatic centering chuck a top - notch clamping workpiece. Workpiece clamping is the process of workpiece positioning and clamping in lathe or fixture. The structure of three-jaw automatic centering chuck is shown in the figure. When the wrench is inserted into the square hole 1 of the small bevel gear 2 to rotate, the small bevel gear 2 drives the big bevel gear 3 to rotate, the back of the big bevel gear 3 is plane thread 4, the back of the claw 5 is meshing with plane thread, so when the plane thread rotates, it drives the three claws to make centripetal or centrifugal movement at the same time.
Three-jaw chuck is also called three-jaw self-centering chuck. It determines the rotating center of the workpiece according to the circumference of the clamping part of the workpiece, but its centering precision is not very high. Generally according to the use of the occasion, in fine turning, grinding and the use of universal dividing head milling parts with high precision, select the clamping accuracy of the three jaw chuck, and in the rough car and invisible precision requirements of grinding, milling and other processing, the use of the clamping accuracy of the three jaw chuck.
The principle of clamping workpiece with three-jaw chuck is to use the chuck wrench to rotate any one of the three umbrella teeth on the circle. Thus drive the plane thread to rotate and drive three claws to move together, play the role of self-centering clamping workpiece; From the mechanical structure, the chuck three umbrella teeth have the same function, but after careful testing, three umbrella teeth clamping workpiece precision is not the same, the difference is also large. In the test, three umbrella teeth are marked with a,b and c respectively; The test rods and test methods used for testing are shown in figure 1. The number of test rods is 10, and they are arranged in sequence. The test results are listed in table 1, table 2 and table 3.
It can be concluded from the circumferential pulsation values measured in the above three tables and the detection situation that whether the centering accuracy is high or low, the accuracy of the three umbrella teeth clamping workpiece is different, and one of them is stable and high. In high precision machining, if we use this feature, the workpiece processing quality can be further guaranteed.
