The 20kg continuous casting machine of Shandong Aluminum Co., Ltd. Electrolytic Aluminum Plant was purchased from Fushun Aluminum Factory in 1985. It is mainly used for continuous automatic stacking of 20kg aluminum ingots with a design capacity of 15t/h. The main work flow is: high-temperature aluminum water flows from the melting furnace to the mold, and naturally cools as the casting machine moves forward. When it reaches the vicinity of the sink, it relies on the impact of the mold and the metal object, and the aluminum ingot pops out from the mold. And fell into the sink.
It is cooled by circulating water as the cylinder moves forward; after cooling, it is automatically stacked by the system. During the stacking process, each of the five aluminum ingots is a layer, and the upper and lower directions of the same layer of aluminum ingots are sequentially crossed, and the orientation of the aluminum ingot is controlled by the lifting cylinder and the turning cylinder. The stacking direction between the aluminum ingot layer and the layer sequentially intersects. After being stacked to the set height, it is transported by the forklift.
The original automatic control system uses F-30 series PLC as the controller, and the limit switches are all impact mechanical limit switches. Due to problems in design and programming, after several years of operation, the system exposed many problems.
1 limit switch has a high failure rate and is often damaged; and often mis-signs. In the system, the aluminum ingot is released from the mold by the elastic force generated by the metal impact, and the shock generated by the impact is enough to cause the contact of the mechanical limit switch to malfunction.
2 The system often malfunctions, and in serious cases, equipment accidents may occur due to malfunctions. If the mechanical limiter is in the process of raising the aluminum ingot, if the rising limit switch malfunctions, the trolley will move to the left in the case of insufficient height, causing the mechanical claw to collide with the platform, and both are damaged.
3 The mechanical claw catching ingot is unreliable, causing system confusion and increasing the workload of the operation work. The system is seriously worn, especially the limit switches and mechanical claws, which need to be repaired almost once a week, the maintenance amount is large, and the equipment operation rate is reduced.
In response to problems in the system, the company improved some parts of the system's operation in 2002.
First, the improvement of electronic control system
20kg aluminum ingot continuous casting machine electrical control system and improvement, using the current popular CPMIA programmable controller, select the basic unit CPM1A-40CDR-A as the CPU unit, its I / O points is 24/16, the output is the relay Output. The CPM1A-20EDR expansion unit is selected to meet the system design requirements. The expansion unit has 12/8 I/O points and uses relay output.
The limit switch adopts non-contact photoelectric switch and proximity switch, and the action is more accurate. In the programming, combined with the actual situation of production, full consideration of various abnormal factors makes the system operation more stable, reliable and safe.
For safety reasons, the control loop of the mechanical claw lift motor has an increase limit switch. The use of mechanical switches for the rise limit is relatively reliable, because the rise limit switch only operates in the event of an accident, and the number of actions is small. If an electronic switch is used, there is a problem that the life affects the reliability. Other switches can be selected according to the size of the field space, 20~30cm photoelectric switch or TL-N10ME124V2~3cm proximity switch.
The output action of the PLC is isolated by the intermediate relay to avoid PLC damage caused by external faults (such as stringing high voltage, etc.), and it is convenient for maintenance. The fault point can be judged according to whether the corresponding relay operates, so as to narrow the search range.
In order to facilitate on-site scheduling and emergency processing, a manual/stop/automatic control selection function is also set, and the manual/automatic conversion is realized by the master switch.
Second, the main features of the improvement
1 Although the cylinder grabbing action is relatively reliable, in practice, due to various factors, such as the size of the cast aluminum ingot is manually controlled, the size of each aluminum ingot may not be exactly the same; due to mechanical mechanism wear and the like The arrangement of 5 aluminum ingots is not very regular, and occasionally there will be confusion in the ingot. At this time, the corresponding button can be pressed to input a signal to the control program, and the lifting and lowering action of the mechanical claw is automatically disconnected by the soft switch in the program, and the operator can manually adjust according to the corresponding button.
2 The mechanical claw before the transformation is in the process of lowering the aluminum ingot and rising to a sufficient height, and the left-hand return is ready for the next cycle. Due to the programming and the error of the limit switch, the mechanical claw does not rise to the set height and the left line Return trip, collision with the platform. In this modification, corresponding protection measures are taken in the control program. During the left or right stroke of the mechanical claw, the system will automatically adjust to raise the height of the mechanical claws to avoid collision with the platform.
3 The input signals of each limit switch are processed to eliminate the “jitterâ€. The signal input to the programmable controller for each limit switch is added with a delay time of 0.5 to 1 s according to the actual situation to avoid The system is confused due to a malfunction of the limit switch. Moreover, the programming adopts the "state" mode, that is, each step of the mechanical claw acts as a state, and the conversion of each state is controlled by only one input signal, thereby greatly enhancing the reliability of the system control. The working power supply of the limit switch does not use the DC24 power supply of the PLC itself, but uses an external power supply, so as to avoid burning the PLC due to large power consumption.
5 Push, pull, lift, pick, turn, grab spindle, steering, car cylinder action can be manual, stop, automatic control, easy to use and flexible. When the master switch is turned to the "middle position", it is in the off state, and it cannot be controlled manually or automatically.
5 Whether the mechanical claw is turned or not can be adjusted manually at any time.
6 The coordination of each action sequence is controlled by the program, which is accurate and reliable.
Before the improvement, the operator not only had a large workload, but the actual production capacity of the equipment was only 1/3 of the design capacity. After the improvement, the number of operators was reduced from 3 to 1 person, and the capital investment required for the transformation was only 700 yuan, and the economic benefits were very significant. The improvement is based on the original aluminum ingot production combined with existing equipment, and can be used as reference for the equipment transformation of small and medium-sized electrolytic aluminum plants.
It is cooled by circulating water as the cylinder moves forward; after cooling, it is automatically stacked by the system. During the stacking process, each of the five aluminum ingots is a layer, and the upper and lower directions of the same layer of aluminum ingots are sequentially crossed, and the orientation of the aluminum ingot is controlled by the lifting cylinder and the turning cylinder. The stacking direction between the aluminum ingot layer and the layer sequentially intersects. After being stacked to the set height, it is transported by the forklift.
The original automatic control system uses F-30 series PLC as the controller, and the limit switches are all impact mechanical limit switches. Due to problems in design and programming, after several years of operation, the system exposed many problems.
1 limit switch has a high failure rate and is often damaged; and often mis-signs. In the system, the aluminum ingot is released from the mold by the elastic force generated by the metal impact, and the shock generated by the impact is enough to cause the contact of the mechanical limit switch to malfunction.
2 The system often malfunctions, and in serious cases, equipment accidents may occur due to malfunctions. If the mechanical limiter is in the process of raising the aluminum ingot, if the rising limit switch malfunctions, the trolley will move to the left in the case of insufficient height, causing the mechanical claw to collide with the platform, and both are damaged.
3 The mechanical claw catching ingot is unreliable, causing system confusion and increasing the workload of the operation work. The system is seriously worn, especially the limit switches and mechanical claws, which need to be repaired almost once a week, the maintenance amount is large, and the equipment operation rate is reduced.
In response to problems in the system, the company improved some parts of the system's operation in 2002.
First, the improvement of electronic control system
20kg aluminum ingot continuous casting machine electrical control system and improvement, using the current popular CPMIA programmable controller, select the basic unit CPM1A-40CDR-A as the CPU unit, its I / O points is 24/16, the output is the relay Output. The CPM1A-20EDR expansion unit is selected to meet the system design requirements. The expansion unit has 12/8 I/O points and uses relay output.
The limit switch adopts non-contact photoelectric switch and proximity switch, and the action is more accurate. In the programming, combined with the actual situation of production, full consideration of various abnormal factors makes the system operation more stable, reliable and safe.
For safety reasons, the control loop of the mechanical claw lift motor has an increase limit switch. The use of mechanical switches for the rise limit is relatively reliable, because the rise limit switch only operates in the event of an accident, and the number of actions is small. If an electronic switch is used, there is a problem that the life affects the reliability. Other switches can be selected according to the size of the field space, 20~30cm photoelectric switch or TL-N10ME124V2~3cm proximity switch.
The output action of the PLC is isolated by the intermediate relay to avoid PLC damage caused by external faults (such as stringing high voltage, etc.), and it is convenient for maintenance. The fault point can be judged according to whether the corresponding relay operates, so as to narrow the search range.
In order to facilitate on-site scheduling and emergency processing, a manual/stop/automatic control selection function is also set, and the manual/automatic conversion is realized by the master switch.
Second, the main features of the improvement
1 Although the cylinder grabbing action is relatively reliable, in practice, due to various factors, such as the size of the cast aluminum ingot is manually controlled, the size of each aluminum ingot may not be exactly the same; due to mechanical mechanism wear and the like The arrangement of 5 aluminum ingots is not very regular, and occasionally there will be confusion in the ingot. At this time, the corresponding button can be pressed to input a signal to the control program, and the lifting and lowering action of the mechanical claw is automatically disconnected by the soft switch in the program, and the operator can manually adjust according to the corresponding button.
2 The mechanical claw before the transformation is in the process of lowering the aluminum ingot and rising to a sufficient height, and the left-hand return is ready for the next cycle. Due to the programming and the error of the limit switch, the mechanical claw does not rise to the set height and the left line Return trip, collision with the platform. In this modification, corresponding protection measures are taken in the control program. During the left or right stroke of the mechanical claw, the system will automatically adjust to raise the height of the mechanical claws to avoid collision with the platform.
3 The input signals of each limit switch are processed to eliminate the “jitterâ€. The signal input to the programmable controller for each limit switch is added with a delay time of 0.5 to 1 s according to the actual situation to avoid The system is confused due to a malfunction of the limit switch. Moreover, the programming adopts the "state" mode, that is, each step of the mechanical claw acts as a state, and the conversion of each state is controlled by only one input signal, thereby greatly enhancing the reliability of the system control. The working power supply of the limit switch does not use the DC24 power supply of the PLC itself, but uses an external power supply, so as to avoid burning the PLC due to large power consumption.
5 Push, pull, lift, pick, turn, grab spindle, steering, car cylinder action can be manual, stop, automatic control, easy to use and flexible. When the master switch is turned to the "middle position", it is in the off state, and it cannot be controlled manually or automatically.
5 Whether the mechanical claw is turned or not can be adjusted manually at any time.
6 The coordination of each action sequence is controlled by the program, which is accurate and reliable.
Before the improvement, the operator not only had a large workload, but the actual production capacity of the equipment was only 1/3 of the design capacity. After the improvement, the number of operators was reduced from 3 to 1 person, and the capital investment required for the transformation was only 700 yuan, and the economic benefits were very significant. The improvement is based on the original aluminum ingot production combined with existing equipment, and can be used as reference for the equipment transformation of small and medium-sized electrolytic aluminum plants.
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