A PLC-based cooling control device for finishing rolling motor

Abstract

The utility model relates to a PLC-based finishing motor cooling control device, comprising a water cooling system and an air cooling system; further comprising a PLC control system, a water cooling frequency converter, an air cooling frequency converter, a temperature patrol meter, a hot metal detector, an audible and visual alarm, a temperature sensor and a host computer human-machine interface, wherein the water cooling frequency converter, the air cooling frequency converter and the hot metal detector are connected to the PLC control system, the temperature sensor is respectively connected to the PLC control system and the temperature patrol meter, the temperature patrol meter is connected to the audible and visual alarm, and the PLC control system is connected to the host computer human-machine interface via a communication cable; the utility model separates the working and standby states of a finishing rolling multi-stand continuous rolling DC motor in a steel plant, and provides a working mode of an air cooling system in a working state, which can save electric energy, ensure the cooling effect, provide an alarm function, ensure the safe use of the DC motor, increase the service life of the DC motor, and ensure system safety.

Description

Technical Field

[0001] The utility model relates to the technical field of steel rolling equipment, in particular to a PLC-based finishing rolling motor cooling control device. Background Art

[0002] In most current steel rolling production processes, DC motors are widely used due to their large starting torque, smooth speed regulation, and low price of automatic speed regulation devices. In a multi-stand continuous rolling finishing mill, it is generally composed of multiple DC motors. According to the needs of the steel rolling process and the actual load conditions, the operating curve of the DC motor is also different, that is, the speed and working current of each DC motor are different, and the operating curve of the DC motor will also change when rolling steel billets of different specifications. In the actual working process of the DC motor, large current will generate heat. Excessive heat and long-term operation will cause the temperature rise of the stator and rotor coils of the motor itself. Excessive temperature will reduce the insulation performance of the insulating paint on the surface of the coil. If the continuous temperature rise reaches a certain level, the motor may burn out, and the consequences will be disastrous.

[0003] The cooling system of the DC motor includes an air cooling system and a water cooling system. The water cooling system includes a clean circulating water pool, a water pump, a pressure gauge, a gate valve, a pipe, and a radiator. The air cooling system includes a fan and a contactor.

[0004] The working process is as follows: the water cooling system is always in working condition, and the water pump runs to transport the water in the clean water pool to the radiator branch pipe of the DC motor at a certain pressure. There is a certain amount of heat inside the motor, and the heat heats the cooling water in the radiator branch pipe. At the same time, the circulation of cooling water takes away the heat inside the motor. At the same time, when the motor closing signal is given, the air cooling system starts to work, and the cooling fan starts to run. The wind blows on the radiator branch pipe, and the circulation of the wind can also take away part of the heat of the radiator. The combined effect of air cooling and water cooling can complete the cooling of the DC motor.

[0005] The above working process has the following disadvantages in practical application:

[0006] After the DC motor is closed, the cooling fan starts to work at the rated frequency. The motor is not started when the switch is closed, and the temperature is low. Single water cooling can complete the cooling work. Even when the DC motor starts to run, if it is not rolling steel, the no-load current is very small, and the temperature rise is also very low under small current. Therefore, if the cooling fan has not been effectively adjusted, it will cause waste of electricity and reduce the life of the air cooling system equipment after long-term operation.

[0007] Since the water cooling part is always in working condition, the water cooling system in this case will work non-stop all year round. Firstly, it wastes electricity, and secondly, it also affects the life of the entire water cooling system equipment. If it is manually operated and the entire water cooling system is shut down when steel is not rolling, the remaining cooling water in the system will freeze in winter, causing the system to paralyze. Summary of the invention

[0008] The utility model provides a PLC-based finishing rolling motor cooling control device, which effectively solves the cooling problem of multiple continuous rolling DC motors in a steel mill, can achieve the purpose of energy saving, and can achieve the effect of safe and stable cooling.

[0009] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0010] A PLC-based finishing mill motor cooling control device, including a water cooling system and an air cooling system; also includes a PLC control system, a water-cooled frequency converter, an air-cooled frequency converter, a temperature inspection instrument, a hot metal detector, an audible and visual alarm, a temperature sensor and a host computer human-machine interface, wherein the water-cooled frequency converter, the air-cooled frequency converter and the hot metal detector are connected to the PLC control system, the temperature sensor is respectively connected to the PLC control system and the temperature inspection instrument, the temperature inspection instrument is connected to the audible and visual alarm, and the PLC control system is connected to the host computer human-machine interface via a communication cable;

[0011] The PLC control system is arranged in an electric control cabinet, the temperature inspection instrument is arranged on an instrument panel of the electric control cabinet, the hot metal detector is arranged at the front and rear positions of the finishing mill respectively, and the temperature sensor is arranged inside the motor to be cooled.

[0012] Furthermore, the water cooling system includes a clean water tank, a liquid level float, a water pump, a water outlet check valve, a water outlet gate valve, a pressure gauge, a gate valve, a motor radiator, a return water gate valve and a return water check valve. The liquid level float is arranged in the clean water tank, the motor radiator is arranged in the motor to be cooled, the clean water tank is connected to the inlet end of the motor radiator through an outlet pipe, and a water pump, a water outlet check valve, a water outlet gate valve, a pressure gauge and a gate valve are arranged on the outlet pipe in sequence, the outlet end of the motor radiator is connected to the clean water tank through a return water pipe, a return water gate valve and a return water check valve are arranged on the return water pipe in sequence, and the pressure gauge is connected to a PLC control system.

[0013] Furthermore, the air cooling system includes a fan and a contactor, the fan is connected to the contactor, and the contactor is connected to the three-phase output terminals of the air cooling inverter.

[0014] Furthermore, the temperature sensor adopts a thermal resistor PT100.

[0015] Furthermore, the PLC control system includes a CPU, an analog input module, an analog output module and a digital output module. The CPU is connected to a host computer human-machine interface through a communication port, the analog input module is connected to a temperature sensor, the analog output module is connected to a water-cooled inverter, and the digital output module is connected to an air-cooled inverter.

[0016] Furthermore, it also includes a three-phase input inductor, a three-phase output inductor, a fuse, a braking unit and an indicator light. The input terminals of the air-cooled inverter and the water-cooled inverter are connected to their respective three-phase input inductors, the input end of the three-phase input inductor is connected to the fuse, the braking terminals of the air-cooled inverter and the water-cooled inverter are connected to their respective braking units, and the output terminals are connected to indicator lights to display fault and operating status; the three-phase output terminals of the air-cooled inverter are connected to the three-phase output inductor, and the three-phase output inductor is connected to the fan; the three-phase output terminals of the water-cooled inverter are connected to the three-phase output inductor, and the three-phase output inductor is connected to the fan.

[0017] Furthermore, the number of gate valves, the number of motor radiators and the number of motors correspond one to one. When there are multiple motors to be cooled, a single gate valve and a single motor radiator form a series pipeline, and multiple series pipelines are connected in parallel.

[0018] Furthermore, the pressure gauge is a remote pressure gauge.

[0019] Compared with the prior art, the beneficial effects of the utility model are:

[0020] 1) The working frequency of the water pump and fan used for cooling is adjusted through a water-cooled inverter, an air-cooled inverter, a pressure gauge, a temperature sensor, a hot metal detector and a PLC control system, the working and standby states of the DC motor of the finishing multi-stand rolling mill in the steel plant are separated, and a working mode of the air cooling system in the working state is provided, which can save electricity and ensure the cooling effect;

[0021] 2) Through the upper computer human-machine interface, temperature inspection instrument and sound and light alarm, both the upper computer human-machine interface and the sound and light alarm can provide alarm functions in the case of motor over-temperature and abnormal working state, ensuring the safety of DC motor use and prolonging the service life of DC motor;

[0022] 3) Provide a water cooling system with an implementation plan that reduces costs and increases efficiency while maintaining safety, thus achieving better economic results. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the utility model.

[0024] Figure 2 It is a structural schematic diagram of the water cooling system of the utility model.

[0025] Figure 3 This is a wiring diagram of the air-cooled frequency converter of the utility model.

[0026] Figure 4 It is a wiring diagram of the water-cooled frequency converter of the utility model.

[0027] Figure 5 This is a wiring diagram of the temperature patrol meter described in the utility model.

[0028] In the figure: 1. Clean water tank 2. Liquid level float 3. Water pump 4. Water outlet check valve 5. Water outlet gate valve 6. Pressure gauge 7. Gate valve 8. Motor radiator 9. Backwater gate valve 10. Backwater check valve DETAILED DESCRIPTION

[0029] The specific implementation of the utility model is further described below in conjunction with the accompanying drawings:

[0030] See Figure 1 , is a schematic diagram of the structure of the utility model. The utility model is a PLC-based finishing mill motor cooling control device, including a water cooling system and an air cooling system;

[0031] It also includes an S7-Smart PLC control system, a water-cooled frequency converter, an air-cooled frequency converter, a temperature inspection meter, a hot metal detector, an audible and visual alarm BJ1, a thermal resistor PT100, and a WinCC 7.0 host computer human-machine interface. The water-cooled frequency converter, the air-cooled frequency converter, and the hot metal detector are connected to the PLC control system. The temperature sensor is respectively connected to the PLC control system and the temperature inspection meter. The temperature inspection meter is connected to the audible and visual alarm BJ1. The PLC control system is connected to the host computer human-machine interface via a communication cable. The WinCC 7.0 host computer human-machine interface is arranged on an operating table in a finishing operation room.

[0032] The PLC control system is arranged in an electric control cabinet, the temperature inspection instrument is arranged on an instrument panel of the electric control cabinet, the hot metal detector is arranged before and after the finishing mill, and the temperature sensor is arranged inside the motor to be cooled.

[0033] See Figure 2The water cooling system includes a clean water tank 1, a liquid level float 2, a water pump 3, a water outlet check valve 4, a water outlet gate valve 5, a remote pressure gauge 6, a gate valve 7, a motor radiator 8, a return gate valve 9 and a return check valve 10. The liquid level float 2 is arranged in the clean water tank 1 to detect the liquid level of the cooling water in the clean water tank 1. The motor radiator 8 is arranged in the motor to be cooled. The clean water tank 1 is connected to the inlet end of the motor radiator 8 through an outlet pipe, and water pumps 11 and 12 are arranged on the outlet pipe in sequence. Pump 3, water outlet check valve 4, water outlet gate valve 5, remote pressure gauge 6 and gate valve 7. The number of gate valves 7 and motor radiators 8 corresponds to the number of motors. A single gate valve 7 and a single motor radiator 8 form a series pipeline. When there are multiple motors to be cooled, multiple series pipelines are connected in parallel and then connected to the clean circulation water tank 1 through a return pipe. A return gate valve 9 and a return check valve 10 are arranged on the return pipe in sequence. The remote pressure gauge 6 is connected to a PLC control system.

[0034] The air cooling system includes a fan and a contactor. Figure 3 The air-cooled inverter selects the inverter model GD350-055G-4INVT. The three-phase input terminals R, S, and T of the air-cooled inverter are connected to the three-phase input reactor L11. The input end of the three-phase input reactor L11 is connected to the fuse FU11. The brake terminal of the air-cooled inverter is connected to the brake unit BK. The brake unit BK is provided with a brake resistor. The output terminals R01A and RO2A are respectively connected to the indicator lights HL11 and HL12 to display the fault and operating status. Phase output terminals U, V, and W are connected to the three-phase output inductor L12, and the three-phase output inductor L12 is connected to fans M1-1 and M1-2 through contactors KM11 and KM12 respectively. The DI1~DI4 terminals of the air-cooled inverter are connected to the opening points of relays KA11~KA14 respectively. The digital output module of the PLC control system outputs the fan low-speed, medium-speed, high-speed or fault reset signal to the air-cooled inverter, and the corresponding relay opening point is closed, triggering the low-speed, medium-speed, high-speed or fault reset action of the fan.

[0035] See Figure 4The water-cooled inverter selects the inverter model GD350-132G-4INVT. The three-phase input terminals R, S, and T of the water-cooled inverter are connected to the three-phase input reactor L1. The input end of the three-phase input reactor L1 is connected to the fuse FU1. The brake terminal of the air-cooled inverter is connected to the brake unit BK1. The brake unit BK1 is provided with a brake resistor. The output terminals R01A and RO2A are respectively connected to the indicator lights HL1 and HL2 to display the fault and operating status. The three-phase output terminals U, V, and W of the air-cooled inverter are connected to the three Phase output inductor L2, the three-phase output inductor L2 is connected to the fan M1 through the contactor KM1, the AI1 and GND terminals of the water-cooled inverter are connected to the analog output module AO terminal of the PLC control system, the DI1~DI3 terminals of the water-cooled inverter are connected to the opening points of relays KA1~KA3, and the digital output module of the PLC control system outputs the running, stopping or fault reset signal of the water pump M1 to the water-cooled inverter, and the corresponding relay opening points KA1~KA3 are closed, triggering the water pump M1 to run, stop or reset the fault.

[0036] The PLC control system includes an S7-200 SmartCPU, an analog input module AI, an analog output module AO and a digital output module DO. The analog input module AI, the analog output module AO and the digital output module DO adopt 6ES7288 series modules. The CPU is connected to a WINCC 7.0 host computer human-machine interface through an INTERNET communication port. The analog input module AI is connected to a thermal resistor PT100. The analog output module AO is connected to a water-cooled inverter. The digital output module is connected to an air-cooled inverter. The I0.0 terminal of the CPU is connected to a hot metal detector.

[0037] See Figure 5 The temperature patrol meter selects the WP-D808 model, terminals A, B, and C are connected to the thermal resistor PT100 in the motor, terminals 01 and O2 are connected to the DC 24V power supply and the relay coil KAX1, the relay contact KAX1 is connected to the sound and light alarm BJ1, and the power terminal of the temperature patrol meter is connected to the DC 24V power output end of the switching power supply.

[0038] Working principle: Take a 9-row finishing mill in a steel mill as an example. The motor is a DC2800KW DC motor, with a total of 9 units. The finishing operator sets the cooling system of the 9 DC motors of the 9-row finishing mill to the working mode through the WinCC monitoring interface on the finishing operation table. After the working mode is started:

[0039] (1) Water cooling system: The PLC S7-200 Smart CPU will adjust the output frequency of the water cooling inverter according to the set value of the pipeline pressure and the feedback value of the remote pressure gauge 6 on the pipeline, thereby adjusting the operating frequency of the water pump 3 motor of the water cooling system to ensure that the working pressure of the water cooling system can meet the requirements of the designed cooling effect;

[0040] (2) The PLC S7-200 Smart CPU pre-assigns a fixed standby frequency instruction to the inverter of each DC motor cooling fan, allowing the inverter to output a low-frequency working voltage, and the cooling fan will run at a low speed. When the hot metal detector before the finishing mill detects the arrival of the steel billet, the PLC receives the input signal of the hot metal detector and then gives a fixed working frequency instruction to each air-cooled inverter, and the cooling fan will run at a working speed. When the hot metal detector after the finishing mill detects the departure of the steel billet, the PLC receives the input signal of the hot metal detector after the finishing mill and controls each cooling fan inverter to return to the standby working state.

[0041] Due to the different process requirements during the finishing multi-stand continuous rolling process, the load current of each motor is different. When a large current passes through, especially in summer, the temperature rise of the motor will increase significantly. When the internal thermal resistor PT100 of a motor detects that the internal temperature of the motor exceeds the normal allowable 50℃, the air-cooled inverter of this motor will enter the power frequency 50HZ state until the temperature of this motor is detected to be 20℃ through the internal PT100 thermal resistor, and this motor switches to the power saving working mode;

[0042] If the motor is always in the industrial frequency state of 50HZ, and the temperature of a motor continues to rise and reaches 90℃, an alarm prompt for the motor's overtemperature will pop up on WinCC. To be on the safe side, the temperature patrol meter on the instrument panel of the local electrical control cabinet collects the detection data of the PT100 thermal resistors of 9 DC motors in real time. When the temperature of one of the motors exceeds the set high temperature alarm value of 90℃, the sound and light alarm BJ1 is driven to sound and light alarm. If two alarm prompts are given, the operator must stop production and then carry out maintenance.

[0043] When the WinCC7.0 host computer monitoring interface switches the multi-motor cooling system to standby mode:

[0044] (1) Water cooling system: PLC S7-200 Smart CPU makes the motor of the clean-circuit water pump 3 run at a low speed according to the set value of the pressure on the pipeline and the feedback value of the remote pressure gauge 6 on the pipeline, ensuring that the water flow in the water cooling system is always in a flowing state, thus achieving the purpose of energy saving and ensuring system safety;

[0045] (2) The air cooling system is turned off.

[0046] The cooling process of the entire implementation case above has well achieved the cooling effect of multiple motors of the 9-roll finishing mill in the steel plant, and achieved the purpose of reducing costs and increasing efficiency under the premise of safety and stability, and achieved good use results.

[0047] The above embodiments are implemented based on the technical solution of the utility model, and detailed implementation methods and specific operation processes are given, but the protection scope of the utility model is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A PLC-based finishing mill motor cooling control device, comprising a water cooling system and an air cooling system; characterized in that: It also includes a PLC control system, a water-cooled frequency converter, an air-cooled frequency converter, a temperature inspection meter, a hot metal detector, an audible and visual alarm, a temperature sensor and a host computer human-machine interface, wherein the water-cooled frequency converter, the air-cooled frequency converter and the hot metal detector are connected to the PLC control system, the temperature sensor is respectively connected to the PLC control system and the temperature inspection meter, the temperature inspection meter is connected to the audible and visual alarm, and the PLC control system is connected to the host computer human-machine interface via a communication cable; The PLC control system is arranged in an electric control cabinet, the temperature inspection instrument is arranged on an instrument panel of the electric control cabinet, the hot metal detector is arranged at the front and rear positions of the finishing mill respectively, and the temperature sensor is arranged inside the motor to be cooled.

2. A PLC-based finishing mill motor cooling control device according to claim 1, characterized in that: The water cooling system includes a clean water tank, a liquid level float, a water pump, a water outlet check valve, a water outlet gate valve, a pressure gauge, a gate valve, a motor radiator, a return water gate valve and a return water check valve. The liquid level float is arranged in the clean water tank, and the motor radiator is arranged in the motor to be cooled. The clean water tank is connected to the inlet end of the motor radiator through an outlet pipe, and a water pump, a water outlet check valve, a water outlet gate valve, a pressure gauge and a gate valve are arranged on the outlet pipe in sequence. The outlet end of the motor radiator is connected to the clean water tank through a return water pipe, and a return water gate valve and a return water check valve are arranged on the return water pipe in sequence, and the pressure gauge is connected to a PLC control system.

3. A PLC-based finishing mill motor cooling control device according to claim 1, characterized in that: The air cooling system comprises a fan and a contactor, wherein the fan is connected to the contactor, and the contactor is connected to the three-phase output terminals of the air cooling inverter.

4. A PLC-based finishing mill motor cooling control device according to claim 1, characterized in that: The temperature sensor adopts thermal resistor PT100.

5. The PLC-based finishing mill motor cooling control device according to claim 1, characterized in that: The PLC control system includes a CPU, an analog input module, an analog output module and a digital output module. The CPU is connected to a host computer human-machine interface through a communication port, the analog input module is connected to a temperature sensor, the analog output module is connected to a water-cooled inverter, and the digital output module is connected to an air-cooled inverter.

6. A PLC-based finishing mill motor cooling control device according to claim 1, characterized in that: It also includes a three-phase input reactor, a three-phase output reactor, a fuse, a braking unit and an indicator light. The input terminals of the air-cooled inverter and the water-cooled inverter are connected to their respective three-phase input reactors, the input end of the three-phase input reactor is connected to the fuse, the braking terminals of the air-cooled inverter and the water-cooled inverter are connected to their respective braking units, and the output terminals are connected to indicator lights to display faults and operating status; the three-phase output terminals of the air-cooled inverter are connected to the three-phase output reactor, and the three-phase output reactor is connected to the fan; the three-phase output terminals of the water-cooled inverter are connected to the three-phase output reactor, and the three-phase output reactor is connected to the fan.

7. A PLC-based finishing mill motor cooling control device according to claim 2, characterized in that: The number of gate valves, the number of motor radiators and the number of motors correspond one to one. When there are multiple motors to be cooled, a single gate valve and a single motor radiator form a series pipeline, and multiple series pipelines are connected in parallel.

8. The PLC-based finishing mill motor cooling control device according to claim 2 is characterized in that: The pressure gauge is a remote pressure gauge.

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