For the operators of CNC gantry milling, accuracy has always been the pursuit of operators, and in actual use, there will often be various errors that will cause the accuracy of the machine tool to decline. Take a look at the relevant knowledge about various errors of gantry milling and how to improve the accuracy of the machine tool.
1. Programming error: CNC machine tools are different from ordinary machine tools. The machining accuracy is not only related to the machining process, but also to the programming before machining. Due to the principle of program control itself, programming errors are unavoidable.
2. Interpolation error: When machining a workpiece on an economical CNC machine tool, the slanted straight line is formed by the tool walking along the two coordinate axis directions on the plane to form a zigzag line, which causes the workpiece surface to be sawtooth-shaped and cause interpolation errors. There are many factors that cause interpolation errors. The more critical ones include machine tool resolution, pulse uniformity, dynamic characteristics of the control system, and interpolation methods and algorithms.
3. Cumulative error: The cumulative error of the machine tool will also be generated during the interpolation operation. When it reaches a certain value, it will cause the machine tool to move and position error, which will affect the machining accuracy.
1) When inserting the reference point return, when instructing the machine tool to return to the reference point, each coordinate will be cleared to zero, which eliminates the cumulative error of the CNC system operation.
2) Try to program in a way that uses a certain fixed point (origin of workpiece coordinates) as the reference, and each piece of program and the entire machining process are based on this. Incremental programming is based on the previous point, and continuous execution of multiple sections of the program will inevitably produce cumulative errors.
In addition, there is another form of error that is worthy of our attention. That is the gap error of the feed mechanism of the machine tool. When the movement is reversed, the gap of the feed mechanism has a greater impact on the machining accuracy of the machine tool. Especially when the dimensional accuracy of the processed parts is close to the repeated positioning accuracy of the gantry milling machine, the influence is greater. Therefore, taking some corresponding measures in NC programming and machining can improve machining accuracy. During the finishing process, the tool moves in the radial direction to keep the size continuously increasing, and the tool moves in the axial direction to keep the size continuously to the left, so the influence of the backlash of the machine tool is eliminated.
Shandong Zecheng CNC Machinery Manufacturing Co., Ltd.'s main products are CNC lathes, CNC milling machines, machining centers, gantry machining centers, gantry milling machines, composite machine tools, pipe thread lathes, wheel machining lathes, machine tool casting, etc., the company's products have been exported to 100 Multiple countries and regions. welcome to order!