Application of Emerson Inverter in Milling Machine for Milling Machine

The transformation plan is: 1. The table is dragged to retain the original mechanical reducer, and a 1:75 worm gear reducer is added. The 55kW DC main motor that reciprocates the original drag table is removed and changed to a 5.5kW 4-stage AC asynchronous motor. It is driven by Emerson EV2000-4T0075G 7.5kW G-type inverter. Because the table advances slowly, only 2cm is required per minute, so the main motor power of the table is not necessarily large. Increasing the mechanical reduction ratio is to make the inverter work above 10Hz, avoiding the low-speed crawling phenomenon of the working platform. The inverter power selection is one level larger than the motor to prevent the inverter from overcurrent at low speed. The fact that the workbench cannot produce low-speed crawling is the key point of the transformation. Workbench motor control requirements: use the button to achieve forward and reverse, stop. There are two ways to give the frequency: 1. Adjustable speed (0~50Hz). 2. Fixed high speed gear: 80Hz. The adjustable speed gear allows the table to be adjusted in speed when milling, and the fixed high-speed gear allows the table to move quickly without manual milling. The adjustable speed gear is realized by the remote control box, and the fixed high-speed gear is realized by the switch. The method is to close the inverter X3 with a switch, short-circuit the X1 and X2 terminals, and the switching frequency given channel is given by the VCI analog. When the switch is disconnected, The number is given 3 (serial port given).

2. Remove the original planing knife and accessory device on the gantry beam beam holder, install the upper milling cutter and the vertical milling power head (equivalent to a gear reducer). The output shaft of the power head drives the milling cutter to rotate. The power head input shaft is 7.5. kW 4-level AC asynchronous motor drive with EV2000-4T0075G inverter. Control requirements: use the button to achieve forward and reverse, stop, the frequency is adjusted in the remote control box.

3. The beam cutter (that is, the milling cutter moves horizontally left and right) The motor is originally a 3.7kW 4-level AC asynchronous machine. It only uses one EV2000—4T0037G inverter. The control method is the same as that of the workbench. There are two ways to set the speed. :1. The remote control box serial port is given (0~50Hz), 2. The switch is turned on and fixed to 80Hz. The method is also to close the inverter X3 with the switch, short-circuit the X1 and X2 terminals, and switch the frequency given channel to The VCI analog is given, and when the switch is off, the digital reference is 3 (serial port reference). Specific parameters: F7.00=22, F7.01=23, F7.03=24. Here VCI analog is given by short-circuiting the inverter terminals VRF and VCI, which is equivalent to the maximum value of VCI=10V. By setting F0.05=80Hz, f0.12=80Hz, f1.07=80Hz, the switch is turned on. Set 80Hz.

4. The side milling power head motor is a 7.5kW 4-level AC asynchronous motor with EV2000-4T0075G inverter. The terminal is given the positive and negative rotation, and only the remote control panel is used to change the frequency, which is exactly the same as the vertical milling power head control. The R485 bus of the remote control panel is connected to all R485 terminals of the inverter. The frequency setting of all inverters can be adjusted by the remote control panel through serial communication, which simplifies the control circuit.

5. The last problem to be solved is the beam lifting and clamping control, which is also a key point of the transformation. The gantry planer beam is vertically moved up and down according to the height of the workpiece. It is driven by a 1.5kW 4-stage AC asynchronous motor to drive the vertical screw. The beam lift motor rotates forward to raise the beam, and the beam lift motor reverses to lower the beam. Moreover, there is a mechanical clamping device on the beam, which is driven by a 0.75kW AC asynchronous motor. After the beam is moved up and down, the clamping motor rotates forward, so that the clamping plate of the clamping device is pressed tightly against the beam. On the track, the beam does not move up and down when machining the workpiece, thus ensuring the precision of the machining. When the beam is moved up and down, the clamping motor should be reversed in advance, and the beam can be moved up and down after the clamping plate is released. The position of the clamping platen is detected by a two-contact stroke switch. After the clamping platen is pressed into place, the normally closed contact FSK of the stroke switch is closed, the normally open contact JXK is normally open, and when normally released, the normally closed contact FSK is released. Disconnected, normally open contact JXK closed. There is also a detail: when the beam is finished at the end, while the clamping motor is rotating forward, the beam lifting motor should also be rotated for 1~2 seconds, let the beam rise a little, and then the beam is clamped. The purpose is to eliminate the gap between the beam lifting screw. The role of the SJ time relay is to let the beam rise back a few seconds, requiring its action to be closed after the power is turned on, and the contact delay is broken after the power is turned off. The entire beam action only has two buttons for raising and lowering, and the beam clamping and relaxing does not require a button, which is automatically done by the circuit. The beam lifting and clamping motors are not controlled by the frequency converter. The figure below is a typical beam control circuit.

Summary: Due to the use of Emerson EV2000 series inverter, the frequency reference channel can be flexibly switched through the terminal, the serial communication frequency reference and the terminal VCI fixed frequency are given, which is convenient for operation, and the anti-interference ability is improved by using the remote control panel. The circuit is simplified, and the inverter has an overload automatic frequency reduction function, and the workbench motor and the power head motor never have an overload shutdown phenomenon, and the reliability is greatly enhanced.