Application of Emerson CT PLC and Frequency Converter in Horizontal Steel Ball Grinding Machine
1 Introduction
Program-controlled frequency conversion ball processing machine is our company's leading product, production and sales ranks first in the country, and bulk exports to the United States, Germany, Japan, South Korea, Italy and other countries. Product design has absorbed a number of advanced technologies at home and abroad. This article describes the electric drive control part.
Since the 1990s, the frequency conversion drive technology has been improving day by day, and its advantages such as stable speed control, energy saving and consumption reduction, convenience and reliability have been prominent, and it has completely replaced the original slip speed control and DC speed regulation. The programmable controller is easy to program and easy to implement many functions that traditional relay control cannot achieve. System integration automation of PLC and frequency converter has become the preferred solution for product design. RS485 communication requires only two wires. It is safe and reliable, and the transmission distance is widely used in inverters and PLCs. This facilitates the communication between the inverter and the programmable controller. The low cost also increases the competitiveness of the product. .
2 Brief description of the process
The main action of the grinding machine is to rotate the grinding wheel by the main deceleration motor through a pair of V-belt pulleys to drive the main shaft to rotate through the splined web in the unloading pulley. The transmission feeding plate is transmitted by the deceleration motor through a pair of sprocket wheels to reduce the worm gear box. After deceleration, the spur gears in the tray drive the tray to rotate. Both of them need to use different rotation speeds to process different series of steel balls. For this purpose, variable frequency speed control is used. For the safety period, the machine operation protection function is also added to the system. Such as the spindle running monitoring proximity switch, mounted on the spindle pulley of the machine tool, at any time to monitor the movement of the grinding disc to prevent the belt from sliding to cause the grinding disc stuck, when the speed is lower than normal, it will stop the alarm; In addition to the rotation speed detection, it also stops quickly when a ball is added, and resumes automatic operation protection if it returns to normal within a set time.
3 system hardware design
3.1 Single automation platform
Emerson CT's EC10 series of small-scale PLC is a steel ball grinding machine because of its fast operation speed, strong communication network, flexible programming, convenient simulation and running, strong program confidentiality, strong anti-interference ability, and stable and reliable performance. Ball machine PLC preferred automation platform. According to engineering experience, Emerson EV1000 series inverters have extremely low failure rate, can achieve high torque and wide speed range, have excellent anti-trip performance, and have great adaptability to bad power grid, high temperature, humidity and dust. The ability to better meet the diversified use environment of steel ball special processing equipment can realize the integration of single brand and platform technology and become the first choice for project design. The Emerson EC10-1614BRA compact PLC and EV1000-4T0055G and EV1000-2S0007G inverters were used in this project to achieve a single automation platform technology integration. For example, EC10 series PLCs have simple communication instructions for Emerson CT series inverters. One instruction can control the operation control of the inverter.
3.2 Electrical Principle Design
The electrical principle of the main motor of the system (the tray motor control is the same as the main motor) is shown in Figure 1. For the user to adjust the speed and monitor the operating speed, the motor speed is adjusted by the potentiometer, the value is displayed by the linear digital display, not through the communication control. The main button line is directly connected to the PLC's digital input point. PLC——Inverter adopts the communication control mode to start, stop, and jog the motor. Use twisted-pair cable to realize the PLC start-stop control through the RS485 port. This rarely takes up the output point of the PLC and does not need to use it. Contactor control reduces the cost of the machine tool. EV1000 RS485 port direct terminal connection is extremely convenient. However, it should be noted that RS485 port "+", "-" polarity can not be reversed, otherwise there will be no action. Because the inverter itself has a number of protection functions such as over-current, over-voltage, under-voltage, grounding, overheating, and overload. Once an abnormal fault occurs, the normally open point RA and RC are closed, and the inverter immediately stops outputting and will disconnect all actions. And stop the alarm, we will connect it to the PLC input control. When the inverter is faulty, you can check the content displayed on the inverter screen, and use the corresponding measures to deal with the abnormal cause and disposal method of the inverter instruction manual. The protection function of the output of multiple inverters enables us to directly connect to the output terminals of the inverter without the need for additional protection of the motor. For the inverter input protection is relatively weak, in the input with no fuse circuit breaker QF inverse thermal protection.
The EV1000 frequency converter has a wealth of control functions. Because the two control motors of the grinding machine are all deceleration motors, static static tuning is selected, then the highest operating frequency, the lowest operating frequency, the JOG jogging frequency, the acceleration/deceleration time, the frequency command source, the operating signal source, and the parking mode. Parameters such as overload alarm detection and time are set. For the resonance phenomena of individual machine tools, parameters such as carrier frequency, hopping frequency, and motor stability factor are set. In order to achieve light-pressing start-up machine tools and power-saving features, parameters such as torque boost, automatic energy-saving, and AVR functions are set to optimize system performance; parameters such as communication address, communication transmission speed, and communication data format are set. In order to control the PLC to the inverter. EC10 series PLCs have simple communication instructions for Emerson CT series inverters. One instruction can control inverter operation.
5 Concluding remarks
This system uses the frequency changer to realize the stepless speed regulation, satisfies the user the craft diversification demand. Use RS485 communication port, do not take up the output point of PLC, the least wiring, have improved the reliability of the products. The selected Emerson CT frequency converter has a strong self-diagnostic function for easy maintenance. Since the system was put into use, it has been stable in operation, reliable in operation, and has not failed yet. It has a very high price/performance ratio.
Program-controlled frequency conversion ball processing machine is our company's leading product, production and sales ranks first in the country, and bulk exports to the United States, Germany, Japan, South Korea, Italy and other countries. Product design has absorbed a number of advanced technologies at home and abroad. This article describes the electric drive control part.
Since the 1990s, the frequency conversion drive technology has been improving day by day, and its advantages such as stable speed control, energy saving and consumption reduction, convenience and reliability have been prominent, and it has completely replaced the original slip speed control and DC speed regulation. The programmable controller is easy to program and easy to implement many functions that traditional relay control cannot achieve. System integration automation of PLC and frequency converter has become the preferred solution for product design. RS485 communication requires only two wires. It is safe and reliable, and the transmission distance is widely used in inverters and PLCs. This facilitates the communication between the inverter and the programmable controller. The low cost also increases the competitiveness of the product. .
2 Brief description of the process
The main action of the grinding machine is to rotate the grinding wheel by the main deceleration motor through a pair of V-belt pulleys to drive the main shaft to rotate through the splined web in the unloading pulley. The transmission feeding plate is transmitted by the deceleration motor through a pair of sprocket wheels to reduce the worm gear box. After deceleration, the spur gears in the tray drive the tray to rotate. Both of them need to use different rotation speeds to process different series of steel balls. For this purpose, variable frequency speed control is used. For the safety period, the machine operation protection function is also added to the system. Such as the spindle running monitoring proximity switch, mounted on the spindle pulley of the machine tool, at any time to monitor the movement of the grinding disc to prevent the belt from sliding to cause the grinding disc stuck, when the speed is lower than normal, it will stop the alarm; In addition to the rotation speed detection, it also stops quickly when a ball is added, and resumes automatic operation protection if it returns to normal within a set time.
3 system hardware design
3.1 Single automation platform
Emerson CT's EC10 series of small-scale PLC is a steel ball grinding machine because of its fast operation speed, strong communication network, flexible programming, convenient simulation and running, strong program confidentiality, strong anti-interference ability, and stable and reliable performance. Ball machine PLC preferred automation platform. According to engineering experience, Emerson EV1000 series inverters have extremely low failure rate, can achieve high torque and wide speed range, have excellent anti-trip performance, and have great adaptability to bad power grid, high temperature, humidity and dust. The ability to better meet the diversified use environment of steel ball special processing equipment can realize the integration of single brand and platform technology and become the first choice for project design. The Emerson EC10-1614BRA compact PLC and EV1000-4T0055G and EV1000-2S0007G inverters were used in this project to achieve a single automation platform technology integration. For example, EC10 series PLCs have simple communication instructions for Emerson CT series inverters. One instruction can control the operation control of the inverter.
3.2 Electrical Principle Design
The electrical principle of the main motor of the system (the tray motor control is the same as the main motor) is shown in Figure 1. For the user to adjust the speed and monitor the operating speed, the motor speed is adjusted by the potentiometer, the value is displayed by the linear digital display, not through the communication control. The main button line is directly connected to the PLC's digital input point. PLC——Inverter adopts the communication control mode to start, stop, and jog the motor. Use twisted-pair cable to realize the PLC start-stop control through the RS485 port. This rarely takes up the output point of the PLC and does not need to use it. Contactor control reduces the cost of the machine tool. EV1000 RS485 port direct terminal connection is extremely convenient. However, it should be noted that RS485 port "+", "-" polarity can not be reversed, otherwise there will be no action. Because the inverter itself has a number of protection functions such as over-current, over-voltage, under-voltage, grounding, overheating, and overload. Once an abnormal fault occurs, the normally open point RA and RC are closed, and the inverter immediately stops outputting and will disconnect all actions. And stop the alarm, we will connect it to the PLC input control. When the inverter is faulty, you can check the content displayed on the inverter screen, and use the corresponding measures to deal with the abnormal cause and disposal method of the inverter instruction manual. The protection function of the output of multiple inverters enables us to directly connect to the output terminals of the inverter without the need for additional protection of the motor. For the inverter input protection is relatively weak, in the input with no fuse circuit breaker QF inverse thermal protection.
Figure 1 Electrical principle
The EV1000 frequency converter has a wealth of control functions. Because the two control motors of the grinding machine are all deceleration motors, static static tuning is selected, then the highest operating frequency, the lowest operating frequency, the JOG jogging frequency, the acceleration/deceleration time, the frequency command source, the operating signal source, and the parking mode. Parameters such as overload alarm detection and time are set. For the resonance phenomena of individual machine tools, parameters such as carrier frequency, hopping frequency, and motor stability factor are set. In order to achieve light-pressing start-up machine tools and power-saving features, parameters such as torque boost, automatic energy-saving, and AVR functions are set to optimize system performance; parameters such as communication address, communication transmission speed, and communication data format are set. In order to control the PLC to the inverter. EC10 series PLCs have simple communication instructions for Emerson CT series inverters. One instruction can control inverter operation.
5 Concluding remarks
This system uses the frequency changer to realize the stepless speed regulation, satisfies the user the craft diversification demand. Use RS485 communication port, do not take up the output point of PLC, the least wiring, have improved the reliability of the products. The selected Emerson CT frequency converter has a strong self-diagnostic function for easy maintenance. Since the system was put into use, it has been stable in operation, reliable in operation, and has not failed yet. It has a very high price/performance ratio.
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