How to improve the precision of CNC machine tools?(part 2)
Compensation of reverse deviation
CNC Drilling Machine manufacturer shares that domestic CNC machine tools, positioning accuracy has many >0.02mm, but no compensation function. For such machine tools, in some cases, one-way positioning can be realized by programming method to clear the reverse clearance. Under the condition that the mechanical part remains unchanged, as long as the low-speed one-way positioning reaches the interpolation starting point, then interpolation processing can be started. When the reverse is encountered in interpolation feed, the reverse gap value is formally interpolated, which can improve the accuracy of interpolation processing and basically ensure the tolerance requirements of parts.
For other types of CNC machine tools, usually CNC device memory with a number of addresses, dedicated to store the axis of the reverse gap value. When a certain axis of the machine tool is instructed to change the direction of movement, the numerical control device will automatically read the reverse gap value of the axis, the coordinate displacement command value compensation, correction, so that the machine accurately positioned in the command position, eliminate or reduce the adverse impact of the reverse deviation on the accuracy of the machine tool.
General nc system is only a single backlash compensation value is available for use, in order to give attention to both high and low speed motion precision, in addition to want to do better on the mechanical, can only be measured when rapid movement of the negative deviation value as compensation value input, so it is difficult to balance, both rapid positioning precision and the interpolation precision cutting.
For FANUC0i, FANUC18i and other CNC systems, there are two kinds of reverse clearance compensation for fast movement (G00) and low speed cutting feed movement (G01). According to the different feeding mode, the CNC system automatically selects and USES different compensation values to complete the high precision machining.
Input parameter NO11851 (the test speed of G01 can be determined according to the commonly used cutting feed speed and machine tool characteristics); input parameter NO11852 for the reverse clearance value B measured by G00. It should be noted that the fourth digit (RBK) of the parameter number 1800 should be set to 1 if the CNC system is to perform the reverse gap compensation specified separately. If RBK is set to 0, the reverse gap compensation specified separately is not performed. The same compensation values are used for G02, G03, JOG and G01.
That's all for the sharing, thanks for your reading, and we also supply CNC High-Speed Angle Drilling Machine for sale, if you have any demand for our products, just feel free to contact us.
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