What determines the precision of CNC machining of metal parts?
What determines the precision of CNC machining of metal parts?
In NC machining programming, the correct use of methods and skills is of great significance to ensure and improve the accuracy of machined parts. So what determines the precision of CNC machining of metal parts?
The precision of CNC machining of metal parts is determined by the position detection element. The position detection element consists of a detection element (sensor) and a signal processing device. It is an important part of the closed-loop servo system of CNC machine tools. Its function is to detect the actual value of the table position and speed, and send the feedback signal to the numerical control device or servo device to form a closed-loop control. Generally, the detection element uses the principle of light or magnetism to detect the position or speed.Accuracy of CNC machining metal parts
The position detection elements are divided into direct measurement elements and indirect measurement elements according to the detection methods. When linear detection elements are generally used to measure the linear motion of machine tools, it is called direct measurement, and the position closed-loop control formed is called full closed-loop control. The measurement accuracy of CNC metal parts mainly depends on the accuracy of measuring elements, and is not affected by the transmission accuracy of machine tools.
The linear displacement of CNC machining table has an accurate proportional relationship with the rotation angle of driving motor. Therefore, the moving distance of the workbench can be indirectly measured by driving the motor or the rotation angle of the lead screw. This method is called indirect measurement. Position closed-loop control is called semi-closed-loop control.
The measurement accuracy of CNC metal parts depends on the accuracy of detection elements and machine tool feed transmission chain. The machining accuracy of closed-loop CNC machine tools depends largely on the accuracy of the position detection device. CNC machine tools have strict requirements for position detection elements, and its resolution is usually between 0.001~0.01mm and 0.01 mm or lower.
Compared with numerical control devices, the probability of failure of detection components is higher, and cable damage, component pollution, collision deformation and other phenomena often occur. If it is suspected that it is the fault of the detection element, first check whether there is cable breakage, scaling, deformation, etc. You can also judge the quality of the detection element by measuring the output. This requires skilled work on the principle and output signal of the detection element.