First, the function of strong electric control system:
The control signal output by the numerical control device after processing the processing program not only continuously controls the trajectory of the feed motion, but also controls various states of the numerical control machine tool, including the spindle speed control, positive and negative rotation of the spindle, and cooling and cooling. Lubrication device start and stop, tool automatic exchange device, work piece clamping and loosening, indexing worktable indexing, etc. For example, through the M command of the CNC machine program, the control switch on the operation panel of the CNC machine tool, and the detection of input components such as the travel switch, proximity switch, and pressure switch distributed in various parts of the CNC machine tool, the programmable controller in the numerical control device ( PLC) performs logical operations and outputs control signals to drive output components such as intermediate relays, contactors, fuses, solenoid valves, and electromagnetic brakes, and controls the cooling pump, lubrication pump hydraulic system, and pneumatic system.
The power supply and protection circuit consists of a power supply control circuit in a power line of a numerical control machine tool, and a strong wire route connects a power transformer, a control transformer, various circuit breakers, a protection switch, a contactor, and a fuse, so as to assist an AC motor ( Such as cooling pump motor, lubrication pump motor, etc.), electromagnets, clutches and solenoid valves and other power actuators supply power. Strong electric lines cannot be directly connected to control circuits that work under low voltage. Only through circuit breakers, intermediate relays, and other components, can they be converted into switching actions of contacts operating at low DC voltages, so that they can be accepted by relay logic circuits and PLCs. Electrical signals, and vice versa.
Switch signals and code signals are numerical control devices and externally transmitted I/O control signals. When the CNC machine tool does not have a PLC, these signals are directly transmitted between the CNC device and the machine tool; when the CNC device has a PLC, these signals are transmitted through the PLC except for a very few high-speed signals.
Second, strong power control system maintenance:
The machine power control system is mainly composed of the drive of an ordinary AC motor and the logic control device PLC and operation panel of the machine tool. Here is a brief introduction to the maintenance and maintenance of common relay contactor control systems and PLC programmable controllers in the machine power control system.
1, ordinary relay contactor control system maintenance, maintenance CNC machine tools in addition to the CNC system, for economical CNC machine tools, there are ordinary relay contactor control system. The maintenance and maintenance work is mainly about how to take measures to prevent the strong electromagnetic interference of contactors and relays in power cabinets. Contactors, relays and other electromagnetic components in the power cabinets of CNC machine tools are all interference sources of the CNC system. Due to the AC contactor, when the AC motor is frequently started and stopped, the electromagnetic induction phenomenon will cause noises such as spikes or surges in the control circuit of the CNC system and interfere with the normal operation of the system. Therefore, we must take measures to eliminate these electromagnetic interferences. For AC contactor coils, for example, RC networks are connected in parallel at both ends or three-phase input of the AC motor to suppress the interference noise generated by these appliances. In addition, care should be taken to prevent oxidation of contactors, relay contacts, and poor contact of contacts.
2, PLC PLC maintenance, maintenance PLC programmable controller is also an important part of the numerical control machine electrical control. In addition to the auxiliary motion and auxiliary motion control of the machine tool, the CNC power control system also includes the control of the protection switch, various strokes, and limit switches. In the above process, the PLC programmable controller can replace most of the machine tool electrical appliances in the strong electrical control system of the numerical control machine tool, thus realizing the logic control of the spindle, tool change, lubrication, cooling, hydraulic, pneumatic and other systems. When the PLC programmable controller is integrated with the numerical control device, it constitutes a built-in PLC, and when it is located outside the numerical control device, it constitutes a stand-alone PLC. As the structure of the PLC is similar to the CNC device, its maintenance and maintenance can refer to the maintenance and maintenance of the CNC device.
