Speed ​​control method and system for steel plate conveying roller of laser cutting unit

Abstract

The present invention provides a speed control method and system for a steel plate transmission roller conveyor of a laser cutting machine unit. All roller conveyors are segmented according to photoelectric switch signals, and the steel plates on each roller conveyor are tracked. The head and tail position values ​​of the steel plates and the head and tail occupancy signals of the segmented roller conveyors are calculated in real time. A safety distance is set when the steel plates are transmitted on the intermediate roller conveyor, and the speed of the segmented roller conveyor is set according to the occupancy signal and the distance between two adjacent steel plates. A speed change position is set in the final roller conveyor. When the head of the steel plate reaches the speed change position interval, the speed of the final roller conveyor is set according to the signal of the next process. The present invention balances the production efficiency and safety of the roller conveyor transmission process. The intermediate roller conveyor operates at the highest possible speed while maintaining a safety distance to improve production efficiency. The final roller conveyor smoothly switches transmission speeds by setting appropriate speed changes, thereby improving the automation and safety of the roller conveyor transmission process and enhancing production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial automation, and in particular to a speed control method and system for a steel plate transmission roller of a laser cutting unit. Background Art

[0002] With the rapid development of the processing industry, laser cutting machines have been used more and more widely. Whether it is stainless steel, carbon steel, aluminum plate or galvanized plate, iron plate and other metal materials, they can achieve fast, accurate and efficient cutting.

[0003] In a laser cutting machine, steel plates are transported via a conveyor roller conveyor, which consists of numerous drive rollers spaced at regular intervals. The speed of these rollers is controlled by a frequency converter (VFD). On very long conveyor roller conveyors, it's unnecessary to equip each drive roller with a separate VFD. Therefore, a single VFD is often used to control multiple rollers. This reduces the number of VFDs required and fully meets the requirements for transporting steel plates. Furthermore, to position the steel plates on the conveyor roller conveyor, photoelectric switches are installed at intervals along the conveyor roller conveyor. These switches are typically positioned to correspond to the starting and ending positions of one or more VFD-controlled drive rollers. This allows the conveyor roller conveyor to be divided into sections based on the position of the photoelectric switches. The multiple drive rollers between two photoelectric switches form a section, and the drive rollers within this section operate at the same speed.

[0004] When a steel plate needs to be cut, it is first transported from the previous process to the cutting unit's entrance. It is then transferred to the cutting area for positioning. After positioning, laser cutting is performed. The cut plate is then transported via a conveyor roller to the next process, where it may be directly stacked and packaged for transport, or further processed. Generally speaking, the processing speed of the next process is relatively slow, while the plate transport speed should be as high as possible to improve production efficiency. However, in actual production, there have been several incidents of two plates colliding due to excessive speed. Experience has shown that the two plates should maintain a certain safe distance between them. The conveyor runs at high speed when the distance is large, and automatically slows down or stops when the distance falls below the safe distance. This places high demands on real-time positioning and tracking of the plate's head and tail. Furthermore, at the end of the conveyor roller, the plate should change speed based on signals from the next process, smoothly decelerating from the higher transport speed to the processing speed of the next process. Summary of the Invention

[0005] The main purpose of the present invention is to provide a speed control method for the steel plate transmission roller of a laser cutting unit, which takes into account both transmission efficiency and safety, and can also automatically change the speed of the last roller to complete the connection with the next process.

[0006] The technical solution adopted by the present invention is: a speed control method for a steel plate conveying roller of a laser cutting unit, the method comprising the following steps:

[0007] S1. Divide the steel plate conveying roller into sections along the steel plate conveying direction according to the installed photoelectric switches. A roller section is formed between two adjacent photoelectric switches. The positions of the head and tail of the conveyed steel plate are calculated in each roller section, and the head and tail position signals are generated respectively. The last roller section is the end roller section, and the other roller sections are intermediate roller sections.

[0008] S2. Set the safe distance between the steel plates being transported. When the steel plates are transported on the intermediate roller, set the speed of each roller section according to the head and tail occupancy signals and the actual distance between the steel plates.

[0009] S3. Set a speed change range in the last section of the roller. When the head of the transported steel plate reaches the speed change range, the last section of the roller adjusts the speed according to the roller advance signal of the next process and the signal that the steel plate is entering the next process, and monitors whether the plate is stuck. If the plate is stuck, the entire line will stop.

[0010] According to the above scheme, in S1, the steel plate conveying roller is segmented in the following manner:

[0011] On the steel plate conveying roller, photoelectric switches are installed at certain intervals along the steel plate conveying direction. When a steel plate passes through the photoelectric switch position, an identification signal is sent out.

[0012] The transmission rollers between two adjacent photoelectric switches are divided into a group, thereby dividing the entire steel plate transmission roller into several sections. The transmission speed of the transmission rollers in each roller section changes together;

[0013] Taking the starting photoelectric switch position of the steel plate conveying roller as the starting point, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values.

[0014] According to the above scheme, in S1, the real-time position of the transmitted steel plate head is calculated and a head occupancy signal is generated in the following manner:

[0015] Assume that the position of the photoelectric switch at the starting position of a roller segment X is P X，Start The position of the photoelectric switch at the end position of roller segment X is P X，End ; When the steel plate head reaches P X，Start , P X，Start The photoelectric switch at the position sends out a recognition signal, and the steel plate head is located in the roller segment X. The occupancy signal Occupy X，Head Set to 1; when the head of the steel plate reaches P X，End , P X，EndThe photoelectric switch at the position sends out an identification signal, and the steel plate head is located in the roller section X. The occupancy signal Occupy X，Head Reset to 0;

[0016] Occupy signal in the head X，Head During the time period of 1, according to the transmission speed of roller segment X, the distance the steel plate is transmitted in roller segment X is accumulated at each sampling moment to obtain the real-time position of the steel plate head;

[0017] The method for acquiring the transmitted real-time position of the tail of the steel plate and the tail occupancy signal is the same as the transmitted real-time position of the head of the steel plate and the head occupancy signal.

[0018] According to the above scheme, the transmission speed of roller segment X is obtained in the following way:

[0019] The roller section X is provided with a roller with a diameter of Dia X The average speed of the transmission roller at several adjacent sampling moments is taken as the actual speed of the transmission roller at the current moment, and then converted into the transmission speed of the roller segment X.

[0020] According to the above scheme, the calculation formula of the real-time position of the steel plate head is as follows:

[0021] P X，Head =P X，Start +∑N X ·π·Dia X ·T S / G X

[0022] Where, P X，Head is the real-time position of the steel plate head, N X is the average speed of the transmission roller, Dia X is the roller diameter of the transmission roller, T S is the sampling period of PLC, G X is the reduction ratio of the transmission roller drive motor.

[0023] According to the above solution, the S2 is specifically as follows: marking the roller segments along the steel plate transmission direction;

[0024] 1) If there is a steel plate head occupancy signal on roller segment X, and the tail occupancy signals on roller segments X+1 and X+2 are both 0, then roller segment X is moved at the maximum speed V Max run;

[0025] 2) If there is a steel plate head occupancy signal on roller segment X, the tail occupancy signal on roller segment X+1 is 0 and the tail occupancy signal on roller segment X+2 is 1, the distance Dis between the two steel plates is calculated according to the following formula X，X+2 :

[0026] Dis X，X+2 =P X+2，Tail -P X，Head

[0027] P X+2，Tail is the tail position of the steel plate on the roller section X+2, P X，Head is the position of the steel plate head on the roller segment X;

[0028] If Dis X，X+2 >D Safe , then the roller segment X is at the highest speed V Max Run; D Safe For safe distance;

[0029] If Dis X，X+2 <D Safe If the transmission speed of roller section X+2 is 0.0, then set the speed of roller section X to 0.0;

[0030] If Dis X，x+2 <D Safe The transmission speed of roller section X+2 is the preset low speed V Low , then set the speed of roller section X to V Low ;

[0031] 3) If there is a steel plate head occupancy signal on roller segment X and the tail occupancy signal on roller segment X+1 is 1, the speed of roller segment X is set to 0.0.

[0032] According to the above solution, in S3, the speed adjustment is specifically as follows:

[0033] 1) The steel plate head has not yet reached the speed change position. If the steel plate is entering the next process, the Switch signal Next If it is 0, the last roller will run at the highest speed V Max run;

[0034] 2) The steel plate head enters the speed change range. If the steel plate is entering the next process, the Switch signal Next =0, and the next process allows the roller to advance signal Allow Next =1, then the speed of the next process below the last roller is V Next Run; if Switch Next =0 and Allow Next =0, then set the speed of the last roller to 0.0, and wait for Allow Next After it changes to 1, set the speed of the last roller to V Next ;

[0035] 3) When the steel plate head enters the speed change range, if Switch Next=1, the speed of the last roller is set to 0.0.

[0036] According to the above scheme, in S3, it is monitored whether the board is stuck, and the entire line is stopped when the board is stuck, specifically:

[0037] When the signal of the steel plate entering the next process changes from 0 to 1, the timer is started and reset when the signal of the steel plate entering the next process changes from 1 to 0, and the timer T is obtained. Next ;

[0038] Calculate the theoretical transmission time T Trans :T Trans =L Plate / V next , where L Plate is the length of the steel plate, V Next The speed of the next process;

[0039] If T Next >T Trans +T1, T1 is the preset time interval, which immediately triggers the whole line stop signal, and all roller conveyors stop immediately and wait for the operator to handle the fault.

[0040] According to the above scheme, the T1 is 8-12s.

[0041] A speed control system for a steel plate transport roller of a laser cutting unit. The system includes a control unit and a frequency converter. The control unit is used to execute the speed control method for the steel plate transport roller of the laser cutting unit, and sends the speed setting value of each roller segment to the frequency converter, which then sends it to the drive roller of each roller segment.

[0042] The beneficial effects of the present invention are as follows: the speed control method for the steel plate conveying roller conveyor provided by the present invention balances production efficiency and safety during the roller conveyor conveying process. The intermediate roller conveyor runs at the highest possible speed while maintaining a certain safety distance to improve production efficiency. The final roller conveyor smoothly switches conveying speeds by setting appropriate speed shift positions. Faults during the transition process are monitored and the conveyor automatically stops if any. This improves the automation and safety of the roller conveyor conveying process, reduces the workload of operators, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0044] Figure 1 is a flow chart of a method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0046] like Figure 1 As shown, the present invention provides a speed control method for a steel plate conveying roller of a laser cutting machine group, and the method comprises the following steps:

[0047] S1. According to the installed photoelectric switches, the steel plate transmission roller is segmented along the steel plate transmission direction. The area between two adjacent photoelectric switches is a roller segment. The positions of the head and tail of the transmitted steel plate are calculated in each roller segment, and the head and tail occupancy signals are generated respectively; the last roller segment is the end roller segment, and the other roller segments are intermediate roller segments.

[0048] The steel plate conveying roller is segmented as follows:

[0049] On the steel plate conveying roller, photoelectric switches are installed at certain intervals along the steel plate conveying direction. When a steel plate passes through the photoelectric switch position, an identification signal is sent out.

[0050] The transmission rollers between two adjacent photoelectric switches are divided into a group, thereby dividing the entire steel plate transmission roller into several sections. The transmission speed of the transmission rollers in each roller section changes together;

[0051] Taking the starting photoelectric switch position of the steel plate conveying roller as the starting point, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values.

[0052] In this embodiment, when the head of the steel plate reaches the position of the photoelectric switch, a rising edge signal is issued, and a high level is maintained when the steel plate passes until the tail of the steel plate reaches the position of the photoelectric switch, and a falling edge signal is issued, and then a low level is maintained when no steel plate passes.

[0053] The real-time position of the transmitted steel plate head is calculated as follows, and a head occupancy signal is generated:

[0054] Assume that the position of the photoelectric switch at the starting position of a roller segment X is P X，Start The position of the photoelectric switch at the end position of roller segment X is P X，End ; When the steel plate head reaches P X，Start , P X，Start The photoelectric switch at the position sends a recognition signal (in this embodiment, the photoelectric switch at this position sends a rising edge signal), and the steel plate head is located in the roller segment X. The occupancy signal Occupy X，Head Set to 1; when the head of the steel plate reaches P X，End , P X，EndThe photoelectric switch at the position sends a recognition signal (in this embodiment, the photoelectric switch at this position sends a rising edge signal), and the steel plate head is located in the roller section X. The occupancy signal Occupy X，Head Reset to 0;

[0055] Occupy signal in the head X，Head During the time period of 1, according to the transmission speed of roller segment X, the distance the steel plate is transmitted in roller segment X is accumulated at each sampling moment to obtain the real-time position of the steel plate head.

[0056] Assume that in a certain roller section X, the actual speed of the transmission roller is N X，act The speed value fluctuates greatly due to the interference of the on-site environment, so a dynamic average method is used to reduce the influence of interference. The transmission speed of roller segment X is obtained in the following way: a roller with a diameter of Dia is set in roller segment X. X The average speed of the transmission roller at several adjacent sampling moments is calculated as the actual speed of the transmission roller at the current moment, and then converted into the transmission speed of the roller segment X. In this embodiment, the average speed of 5 adjacent sampling moments is used.

[0057] N X (n)=[N X，act (n)+N X，act (n-1)+N X，act (n-2)+N X，act (n-3)+N X，act (n-4)] / 5

[0058] In the formula, n represents the current moment, n-1 represents the previous moment, and so on.

[0059] The calculation formula for the real-time position of the steel plate head is as follows:

[0060] P X，Head =P X，Start +∑N X ·π·Dia X ·T S / G X

[0061] Where PX ，Head is the real-time position of the steel plate head, N X is the average speed of the transmission roller, Dia X is the roller diameter of the transmission roller, T S is the sampling period of PLC, G X is the reduction ratio of the transmission roller drive motor.

[0062] The method for obtaining the real-time position of the tail of the steel plate and the tail occupancy signal transmitted is the same as the real-time position of the head of the steel plate and the head occupancy signal transmitted.

[0063] Assume that the position of the photoelectric switch at the starting position of a roller segment X is P X，Start The position of the photoelectric switch at the end position of roller segment X is P X，End ; When the tail of the steel plate reaches P X，Start , P X，Start The photoelectric switch at the position sends out an identification signal (in this embodiment, the photoelectric switch at this position sends out a falling edge signal), and the occupancy signal Occupy of the tail of the steel plate in the roller segment X is X，Head Set to 1; when the tail of the steel plate reaches P X，End , P X，End The photoelectric switch at the position sends out an identification signal (in this embodiment, the photoelectric switch at this position sends out a falling edge signal), and the occupancy signal Occupy of the tail of the steel plate in the roller section X is X，Head Reset to 0;

[0064] Occupy signal at the tail X，Head During the time when is 1, according to the transmission speed of roller segment X, the distance the steel plate is transmitted in roller segment X is accumulated at each sampling moment to obtain the real-time position of the tail of the steel plate.

[0065] S2. Set the safety distance between the transported steel plates. When transporting steel plates on the intermediate roller, set the speed of each roller segment according to the head and tail occupancy signals and the actual distance between the steel plates. In order to prevent the two steel plates on the roller from colliding, a certain distance needs to be maintained between the two adjacent steel plates. This distance is the safety distance. If the safety distance is set too large, it will affect production efficiency. If it is set too small, there will be safety hazards. Here, the safety distance can be slightly larger than the length of a segmented roller. If the segment lengths are inconsistent, it needs to be slightly larger than the length of the longest segmented roller. In this embodiment, the length of the longest segmented roller is 4.95m, so the safety distance D is set. Safe =5.0m.

[0066] This step is specifically as follows: marking the roller segments along the steel plate transmission direction; when the steel plate runs on the conveyor roller, the distance between the two steel plates can be calculated based on the occupancy signal and the head and tail positions, and the speed of this section of the roller can be adjusted according to the size of the distance.

[0067] 1) If there is a steel plate head occupancy signal on roller segment X, and the tail occupancy signals on roller segments X+1 and X+2 are both 0, it means that the distance between the two steel plates is too large. Then roller segment X is moved at the maximum speed V Max run;

[0068] 2) If there is a steel plate head occupancy signal on roller segment X, the tail occupancy signal on roller segment X+1 is 0 and the tail occupancy signal on roller segment X+2 is 1, the distance Dis between the two steel plates is calculated according to the following formula X，X+2 :

[0069] Dis X，X+2 =P X+2，Tail -P X，Head

[0070] P X+2，Tail is the tail position of the steel plate on the roller section X+2, P X，Head is the position of the steel plate head on the roller segment X;

[0071] If Dis X，X+2 >D Safe , then the roller segment X is at the highest speed V Max Run; D Safe For safe distance;

[0072] If Dis X，X+2 <D Safe If the transmission speed of roller section X+2 is 0.0, then set the speed of roller section X to 0.0;

[0073] If Dis X，X+2 <D Safe The transmission speed of roller section X+2 is the preset low speed V Low , then set the speed of roller section X to V Low .

[0074] 3) If there is a steel plate head occupancy signal on roller segment X and the tail occupancy signal on roller segment X+1 is 1, the speed of roller segment X is set to 0.0.

[0075] S3. Set a speed range in the last roller section. When the head of the steel plate being transported reaches the speed range, the last roller section will adjust the speed based on the signal that allows the roller to advance in the next process and the signal that the steel plate is entering the next process. It will also monitor whether the plate is stuck. If the plate is stuck, the entire line will stop. The last roller section is used to transport the steel plate to the next process. Generally, the processing speed of the next process is lower than the maximum transmission speed of the roller. Therefore, a speed range needs to be determined in the last roller section. When the head of the steel plate reaches the vicinity of the speed range, it will start to change to the speed V of the next process. Next Or stop. After comprehensive consideration, the speed position P change Set it at a safe distance (5.0m) from the starting position of the next process and use P change ±0.2m is used as the speed change interval, which leaves a buffer zone for speed change of the steel plate.

[0076] The next process has two main signals that affect the roller conveyor. One is the signal "Allow" that allows the roller to move forward. Next When the signal is 1, the roller is allowed to transport the steel plate to the next process; there is also a signal that the steel plate is entering the next process. This signal is judged by the entrance photoelectric switch of the next process, which is recorded as Switch Next When the signal is 1, it means that a steel plate is being transferred to the next process. When the signal has a falling edge (the moment when it changes from 1 to 0), it means that the tail of the steel plate has passed the entrance photoelectric switch of the next process, and the transfer of a steel plate is completed.

[0077] When the steel plate head enters the final roller, the speed setting value of the final roller needs to be determined based on the above two signals, which can be divided into three cases:

[0078] 1) The steel plate head has not yet reached the speed change position. If the steel plate is entering the next process, the Switch signal Next If it is 0 (meaning there is no steel plate in front), the last roller will move at the highest speed V Max run;

[0079] 2) The steel plate head enters the speed change range. If the steel plate is entering the next process, the Switch signal Next =0, and the next process allows the roller to advance signal Allow Next =1 (indicates that there is no steel plate in front and it is allowed to be transported to the next process), then the speed of the next process at the end roller is V Next Run; if Switch Next =0 and Alilow Next =0 (meaning there is no steel plate in front but it is not allowed to be transported to the next process), then set the speed of the last roller to 0.0 and wait for Allow Next After it changes to 1, set the speed of the last roller to V Next ;

[0080] 3) When the steel plate head enters the speed change range, if Switch Next =1, the speed of the last roller is set to 0.0.

[0081] Monitor whether the board is stuck and stop the entire line if it is stuck. Specifically:

[0082] When the steel plate is entering the next process, the signal changes from 0 to 1 (Switch Next The timer is started when the signal rises from 1 to 0 and the timer is reset when the steel plate is entering the next process. Next The signal has a falling edge), and the timer timing T is obtained. Next ;

[0083] Calculate the theoretical transmission time T Trans :T Trans =L Plate / V next , where L Plate is the length of the steel plate, V Next The speed of the next process.

[0084] If T Next >T Trans +T1, T1 is a preset time interval, which can be 8-12 seconds, and is 10 seconds in this embodiment. Immediately trigger the full-line stop signal, and all roller tables stop immediately, waiting for the operator to handle the fault.

[0085] The present invention also provides a speed control system for the steel plate transmission roller of a laser cutting machine group. The system includes a control unit and a frequency converter. The control unit is used to execute the speed control method of the steel plate transmission roller of the laser cutting machine group, and sends the speed setting value of each roller segment to the frequency converter, which then sends it to the transmission roller of each roller segment.

[0086] In summary, the speed control method and system for the steel plate transmission roller provided by the present invention first divides all rollers into sections according to the photoelectric switch signal, tracks the steel plates on each roller section, and calculates the head and tail position values ​​of the steel plates and the head and tail occupancy signals of the segmented rollers in real time. A safety distance is set when the steel plates are transmitted on the intermediate rollers, and the speed of the segmented rollers is set according to the occupancy signal and the distance between the two adjacent steel plates. A speed change position is set in the final roller section. When the head of the steel plate reaches the speed change position interval, the speed of the final roller section is set according to the signal of the next process, and each steel plate is monitored to see if it is stuck when being transmitted to the next process. If a jam occurs, the entire line is stopped. This roller speed control method takes into account both the production efficiency and safety of the roller transmission process. The intermediate rollers run at the highest speed possible while maintaining a certain safety distance to improve production efficiency. The final roller section smoothly switches the transmission speed by setting an appropriate speed change position, monitors faults that occur during the transition process, and automatically stops if there are any faults. The automation and safety of the roller conveying process are improved, the labor intensity of the staff is reduced, and the production efficiency is improved.

[0087] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A speed control method for a steel plate conveying roller of a laser cutting unit, characterized in that: This method comprises the following steps: S1. Divide the steel plate conveying roller into sections along the steel plate conveying direction according to the installed photoelectric switches. A roller section is formed between two adjacent photoelectric switches. The positions of the head and tail of the conveyed steel plate are calculated in each roller section, and the head and tail position signals are generated respectively. The last roller section is the end roller section, and the other roller sections are intermediate roller sections. S2. Set the safe distance between the steel plates being transported. When transporting the steel plates on the intermediate roller, set the speed of each roller segment according to the head and tail occupancy signals and the actual distance between the steel plates. S2 specifically includes: marking the roller segments along the steel plate transport direction; 1) If there is a steel plate head occupancy signal on roller section X, and the tail occupancy signals on roller sections X+1 and X+2 are both 0, then roller section X is moved at the highest speed. run; 2) If there is a steel plate head occupancy signal on roller section X, the tail occupancy signal on roller section X+1 is 0 and the tail occupancy signal on roller section X+2 is 1, the distance between the two steel plates is calculated according to the following formula : is the tail position of the steel plate on the roller section X+2, is the position of the steel plate head on the roller segment X; like , then the roller segment X is at the highest speed run; For safe distance; like If the transmission speed of roller section X+2 is 0.0, then set the speed of roller section X to 0.0; like And the transmission speed of roller section X+2 is the preset low speed , then set the speed of roller section X to ; 3) If there is a steel plate head occupancy signal on roller section X, and the tail occupancy signal on roller section X+1 is 1, the speed of roller section X is set to 0.0; S3. Set a speed change interval in the last roller section. When the head of the transported steel plate reaches the speed change interval, the last roller section adjusts the speed according to the roller advance signal of the next process and the signal that the steel plate is entering the next process, and monitors whether the plate is stuck. If the plate is stuck, the entire line will stop. The speed adjustment is specifically as follows: 1) The steel plate head has not yet reached the speed change position, if the steel plate is entering the next process signal If it is 0, the last roller will run at the highest speed. run; 2) The head of the steel plate enters the speed change range, and if the steel plate is entering the next process signal , and the next process allows the roller to advance signal , then the speed of the next process after the last roller is Run; if and , then set the speed of the last roller to 0.0, wait After it changes to 1, the speed of the last roller is set to ; 3) When the steel plate head enters the speed change range, if , then set the speed of the last roller to 0.

0.

2. The speed control method of the steel plate conveying roller of the laser cutting unit according to claim 1 is characterized in that: In the above-mentioned S1, the steel plate conveying roller is segmented in the following manner: On the steel plate conveying roller, photoelectric switches are installed at certain intervals along the steel plate conveying direction. When a steel plate passes through the photoelectric switch position, an identification signal is sent out. The transmission rollers between two adjacent photoelectric switches are divided into a group, thereby dividing the entire steel plate transmission roller into several sections. The transmission speed of the transmission rollers in each roller section changes together; Taking the starting photoelectric switch position of the steel plate conveying roller as the starting point, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values.

3. The speed control method of the steel plate conveying roller of the laser cutting unit according to claim 1 is characterized in that: In the aforementioned S1, the real-time position of the transmitted steel plate head is calculated and a head occupancy signal is generated in the following manner: Assume that the position of the photoelectric switch at the starting position of a roller segment X is , the position of the photoelectric switch at the end position of roller section X is ; When the steel plate head reaches , The photoelectric switch at the position sends out a recognition signal, which indicates that the steel plate head is located in the roller segment X. Set to 1; when the steel plate head reaches , The photoelectric switch at the position sends out a recognition signal, which indicates that the steel plate head is located in the roller section X. Reset to 0; Placeholder signal in the head During the time period of 1, according to the transmission speed of roller segment X, the distance the steel plate is transmitted in roller segment X is accumulated at each sampling moment to obtain the real-time position of the steel plate head; The transmitted real-time position of the tail of the steel plate and the method for obtaining the tail occupancy signal are the same as the transmitted real-time position of the head of the steel plate and the head occupancy signal.

4. The speed control method of the steel plate conveying roller of the laser cutting unit according to claim 3 is characterized in that: The transmission speed of roller section X is obtained in the following way: The roller section X is provided with a roller with a diameter of The average speed of the transmission roller at several adjacent sampling moments is taken as the actual speed of the transmission roller at the current moment, and then converted into the transmission speed of the roller segment X.

5. The speed control method of the steel plate conveying roller of the laser cutting unit according to claim 4 is characterized in that: The calculation formula for the real-time position of the steel plate head is as follows: Where, is the real-time position of the steel plate head, is the average speed of the transmission roller, is the roller diameter of the transmission roller, is the sampling period of the PLC, is the reduction ratio of the transmission roller drive motor.

6. The speed control method of the steel plate conveying roller of the laser cutting unit according to claim 1, characterized in that: In the above S3, it is monitored whether the board is stuck and the entire line is stopped when the board is stuck. Specifically: When the signal of the steel plate entering the next process changes from 0 to 1, the timer is started and the timer is reset when the signal of the steel plate entering the next process changes from 1 to 0. ; Calculating theoretical transmission time : , where is the length of the steel plate, The speed of the next process; like , At the preset time interval, the entire line will be stopped immediately, and all roller conveyors will stop immediately, waiting for the operator to handle the fault.

7. The speed control method of the steel plate conveying roller of the laser cutting machine set according to claim 6, characterized in that: The Take 8-12 seconds.

8. A speed control system for a steel plate conveying roller of a laser cutting unit, characterized by: This system includes a control unit and a frequency converter. The control unit is used to execute the speed control method of the steel plate transmission roller of the laser cutting machine group described in any one of claims 1 to 7, and send the speed setting value of each roller segment to the frequency converter, which then sends it to the transmission roller of each roller segment.

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