Modern cnc lathe and milling machines generally use programmable controllers to replace most machine tool electrical appliances in the electrical cabinets of ordinary machine tools, so as to achieve logical control of the spindle, feed, tool change, lubrication, cooling, hydraulic and pneumatic transmission systems.
CNC milling machine fault diagnosis object
(1) CNC milling machine body (hydraulic, pneumatic and lubrication devices)
For the benchtop cnc milling machine body, because the mechanical parts are in the process of motion friction for a long time, it is particularly important to maintain it, such as the cooling and lubrication of the headstock, the clearance adjustment of the guide rail and ball screw pair, and the Pressure, hydraulic and pneumatic pressure adjustment.
(2) Electrical control system
The electrical control system includes a numerical control system, a servo system, an electrical cabinet for machine tools (also called a strong electrical cabinet), and an operation panel.The interface between the CNC system and the machine’s electrical equipment has four parts:
1) The drive circuit mainly refers to the circuit between the coordinate axis feed drive and the spindle drive.
2) Position feedback circuit, connection circuit between index control system and position detection device.
3) Power supply and protection circuit, power supply in strong current control circuit of index controlled milling machine.
4) Switch signal connection circuit. The switching signal is an I / O control signal between the CNC system and the machine tool. The transmission of the I / O control signal between the CNC system and the machine tool is performed through the I / O interface. The numerical control system outputs various control commands to the I / O interface through the processing of the input switching value to control the action of the high-voltage circuit.
From an electrical point of view, the most obvious feature of benchtop cnc milling machine is to replace the mechanical transmission of ordinary machine tools with electrical drives, and the corresponding main and feed movements are performed by the spindle motor and servo motor.
For cnc lathe and milling machine, special attention should be paid to the buttons, travel switches, proximity switches, relays, solenoid valves and other electrical switches on the machine tool. The reliability of the switch directly affects whether the machine tool can perform the action correctly. The failure of these devices is the most common failure of numerical control equipment. In order to ensure accuracy, CNC milling machines generally use feedback devices (including speed detection devices and position detection devices). Therefore, the quality of the detection device directly affects the movement accuracy and positioning accuracy of the CNC milling machine.
Research data show that improper operation, maintenance and adjustment of CNC equipment accounted for 57% of the entire equipment failure, the faults of the servo system, power supply and electrical control part accounted for 37.5% of the total failure, while the failure of the CNC system accounted for 5.5%.
For operators of benchtop cnc milling machine, it is very important to understand the fault diagnosis object clearly. It can help the operator quickly find the corresponding fault location, eliminate the fault in the fastest time, and promote the normal operation of the machine.