1. Common centring methods for reverse machining
It is mainly aimed at the clamping of flat jaw vice when NC machining parts.
(1) Set the knife with a straight handle round bar. This method is to clamp a round bar with a straight handle on the spindle. Suppose the x-axis is centered: move the spindle slowly close to one side of the workpiece. When it is approaching, use a parallel block to insert the gap between the round bar and the machined surface of the workpiece. When it feels easy to advance, take out the parallel block, continue to move the spindle, and then insert the parallel block. If it is still easy to insert or cannot be inserted, move the spindle again, and so on until it can be inserted, and then reset the x-axis of the relative coordinate to zero; Then move the spindle to the other side of the workpiece, and use the same operation method to get the total value of the X axis. Move the spindle to half of the total value (in the middle of the workpiece) and set the coordinate system. The advantages of this method are simple operation and low value of tools needed; The disadvantage is that there are many operation steps, the process is cumbersome, and the accuracy of tool setting is not high.
(2) Use a dial indicator to set the knife. This method is to flexibly use several accessories of the lever dial indicator to achieve the middle score. The operation method is: put the clamping cap of the lever dial indicator on the spindle, and then install the dial indicator on the clamping cap.
2. Improvement of reverse centering method
Through summarizing all kinds of centring tools, it is found that the use of eccentric edge finder is convenient for centring, and the accuracy of centring is high, but its characteristic is that it can not complete the reverse centring. This is a major disadvantage of the eccentric edge finder in the structure. Therefore, through many tests, after improving the peripheral structure of the eccentric edge finder, it can not only retain the original advantages, but also expand its scope and complete the reverse centering of parts.
First, the outer circle and inner hole of the accessories are completed on the CNC lathe, in which the inner hole is just matched with the edge finder, and the thickness is determined according to the processing of the parts. Next, finish the processing of threaded holes on the side on the drilling machine, and the size of threaded holes depends on the thickness. When the accessories are finished, they are matched with the edge searching end of the edge finder, and then locked with side screws.
The improved centring method can not only ensure the machining accuracy, but also has the advantages of convenient observation and simple and fast operation.