How to positoin the CNC machining center? The operation of CNC machining center includes the steps of analyzing drawings, programming, working, edge finding, tool preparation, tool setting and running procedures. Each step can’t make mistakes, otherwise the processed samples will be scrapped and the production cost will be increased. Especially for the processing of large parts, it needs to be careful and careful. CNC machining centers have one center, so how to locate this machining center? Today we will talk about “how to position the CNC machining center”.
1. Cutter bar positioning: This is similar to the tool positioning of CNC lathe. This needs to compile a positioning program. As shown below, I use Φ 10. The procedure is as follows:
G0 G90 G54 X-5. Y0
G43 H1 Z50
G1 Z-10 F800
G1 X-10 F1000
However, this program cannot be realized on some machine tools, because there is G1 and no speed, the machine tool will think that there is a problem with the program. In this case, G0 can be used for positioning.
2. Fixed positioning: After positioning, find the edge, and then work on the next one, just rely on the positioning directly. Some pliers have a threaded hole on the side, which can also be used for positioning.
3. Line drawing and positioning: When milling a through slot, just draw a line directly on the pliers. Just put it in the approximate position every time you work. The official account of WeChat: UG NC programming. There are also some blank billets, which are larger in size than in the drawings, and can also be positioned in line.
4. Fixture positioning: Generally, the three jaw chuck is used for positioning, and there is no need to find the edge one by one on the clamp. There are also some jobs. The fixtures that need to be done have special pin positioning on them.
The workpiece has 6-point degrees of freedom in space, that is, the degrees of freedom of movement along the three rectangular coordinate axes of X, y and Z and the degrees of freedom of rotation around the three coordinate axes of the workpiece. Therefore, to completely determine the position of the workpiece, these six degrees of freedom must be eliminated. Usually, 6 support points are used to limit the key 6-point degrees of freedom, and each support point limits the corresponding one degree of freedom. For example, on the Y plane of the workpiece, three support points not on the same straight line limit the three degrees of freedom of the workpiece, which is called the main datum plane. The two supporting points arranged along the length direction on the plane limit the other two degrees of freedom of the workpiece. This plane is called the guiding plane; On the XZ plane, the workpiece is limited by a degree of freedom by a support point, which is called the stop moving plane.
Generally speaking, the six point positioning principle is applicable to the positioning of workpieces of any shape. If this principle is violated, the position of workpieces in the fixture can not be completely determined. However When positioning with the six point positioning principle of the workpiece, it must be flexibly used according to the specific processing requirements. Only in this way can the workpiece quickly obtain the correct position in the fixture. Specifically, the six point positioning has the following function.
1. Over positioning: The positioning in which one or several degrees of freedom of the workpiece are repeatedly limited by different positioning elements is called over positioning. When over positioning causes workpiece deformation and affects machining accuracy, it should be strictly prohibited. However, when over positioning does not affect the machining accuracy, but can improve the machining accuracy of NC machining center, it can also be used. Of course, it should be analyzed in detail.
2. Under positioning: According to the machining requirements of NC machining center, the degree of freedom that should be limited but not limited positioning is called under positioning. In general, under positioning is not allowed, because it is difficult to ensure the processing requirements.