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| Design of grinding fluid frequency conversion constant pressure supply system based on PLC |
| ZHANG Kun-Ying |
| Practice Teaching Center, Minnan University of Science and Technology， Shishi 362700， China |
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Abstract The general pressure of the grinding fluid in transferring process is 0.2~0.4 MPa. It will lead to excessive tool wear if the pressure is too high, and can not effectively wash away grinding if the pressure is too low. In order to achieve a constant grinding fluid supply pressure， a constant voltage supply system is needed. PLC and inverter were applied to achieve frequency conversion constant pressure supply of grinding fluid in the designed system. The automatic control of pump rotation and work frequency/variable frequency transformation were realized by PLC. The inverter with internal parameter adjustment function and the sensor of external pressure formed an adaptive PID closed loop control circuit， achieving frequency control of the pump motor. Field operation results show that the system can achieve frequency conversion constant pressure water supply at 0.3~0.33 MPa by setting the inverter internal parameters P2280=5 and P2285=10， and the pressure change can be stabilized within the range of -5%~+5%. The system has been stably operated over 3 years， and can meet the pressure requirements of grinding fluid．
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Published: 28 April 2013
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基于PLC的磨削液变频恒压供给系统设计
磨削液在输送过程中的压力一般要求为0.2～0.4 MPa，过高会导致刀具磨损过快，过低则不能有效冲走磨屑.为达到磨削液供给压力的恒定，需要一个恒压供给系统．本系统应用“PLC+变频器”来实现磨削液的变频恒压供给：PLC实现对泵的轮换，以及泵的工频/变频转换等过程的自动控制；变频器则利用其内置的参数调整功能，与外部设置的压力传感器的反馈组成一个自适应的PID闭环控制回路，实现对水泵电机的变频调速．现场运行结果表明，通过调节变频器内部的P2280和P2285参数，使P2280=5，P2285=10，本系统可实现供水压力在0.3～0.33 MPa范围内的变频恒压供水，其压力变化可稳定在-5%~+5%的范围之内.目前该系统已经稳定运行超过3 a，能满足磨床对磨削液压力的需求．
关键词：
磨削液,
变频,
恒压,
PID
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