What are the interference sources for machining center system
1. External power interference: due to the wide coverage planning of the power grid, there are many devices sharing a power grid, especially the internal changes of the power grid, power switch operation, lightning surge, start-up and stop of large-scale power equipment, harmonics caused by AC and DC transmission equipment, short-circuit transient impact of power grid, etc., are transmitted to the electrical cabinet through the transmission line, resulting in voltage temporary change and grid voltage fluctuation.
2. Interference between digital signal and analog signal: in the process of machining center operation, because the strong current part, the weak current part and the electronic control system touch more electrical parts, the cable used to transmit the signal will sometimes misoperate due to the interference of analog signal output equipment or servo driver or frequency converter during the wiring process, which will affect the normal operation of the equipment Industry.
3. Radiation interference: electromagnetic or electric fields are ubiquitous in nature. In addition to the electric field, the machining center is also affected by the magnetic field.
Some useful ways to avoid interference in machining center:
1. Power isolation method. Various AC and DC power supplies in the control system are obtained by different isolation transformers to prevent electromagnetic coils from interfering with the weak current power supply through the coupling magnetic circuit between transformer coils during power on and power off. Isolation means that the interference source is isolated with isolated components to prevent interference from entering the equipment and ensure the normal operation of the machining center, so as to further suppress and isolate high-frequency interference.
2. Shielding method. Shielding is the most widely used and most useful method now. In shielding method, the transmission way of radiated electromagnetic noise is blocked. The cable with shielding layer is selected, and the signal line and grounding wire or current carrying return line are twisted together, so that the distance between signal and grounding or current carrying return line is the closest, and the mutual inductance between interference source and induced line is as small as possible. However, it should be noted that the shielding wire can only be grounded at one end, and it is necessary to connect or disconnect the grounding wire It is necessary to connect the two lines of shielding layer.
3. Absorption method. Add an absorption circuit to the electrical load circuit, such as adding a freewheeling diode between the two DC electromagnetic clutch coils, pay attention to the polarity, otherwise it will be short circuited. Add resistance capacitance absorber to the main circuit of communication motor and contactor coil of all machine tool subordinate equipment to eliminate back EMF interference, but the power line of absorber in machining center shall not be too long.
