An automatic control method and system for a laser cutting unit

Abstract

This invention discloses an automatic control method and system for a laser cutting machine. It uses a transmission roller encoder to calculate the distance between the head of the workpiece and the cutting position; employs a length grating in conjunction with an X-axis servo motor to achieve precise positioning of the workpiece; controls the Y-axis servo motor for cutting, and performs automatic zero-point calibration of the Y-axis servo motor after cutting; calibrates the laser head distance sensor; and controls the Z-axis servo motor to maintain a stable cutting height throughout the cutting process. The transmission roller conveyor is segmented using installed photoelectric switches, with the middle section operating at the highest possible speed, and the final section smoothly transitioning between speeds. This invention achieves full automation and intelligence of the entire laser cutting process, realizes high-precision steel plate cutting positioning, solves the problem of cutting height control during the cutting process, balances production efficiency and safety in the roller conveyor process, and achieves a smooth transition to the next process.

Description

Technical Field

[0001] This invention relates to the field of electrical control technology, and in particular to an automatic control method and system for a laser cutting machine. Background Technology

[0002] With the rapid development of the processing industry, laser cutting machines have been used more and more widely. They can achieve fast, accurate and efficient cutting of metal materials such as stainless steel, carbon steel, aluminum plates, galvanized plates, and iron plates.

[0003] In laser cutting units, the positioning requirements for axes in all directions are extremely high.

[0004] When cutting steel plates along their length, the cutting length must be 0.05% of the cutting length. If cutting a 6m long object, the positioning accuracy of the cutting length must be within 3mm.

[0005] The servo motor in the cutting direction (the width direction of the steel plate) converts the motor rotation into displacement on the linear guide rail through a gear and lead screw device. When the gear and lead screw mesh, there is an unavoidable gap. Each time a cut is made, the measurement reading of the absolute encoder will have a small offset. After multiple cuts, it becomes a large error. It is necessary to find a way to perform automatic correction after each cut to eliminate the accumulated error.

[0006] Significant fluctuations in cutting height can severely impact the cutting effect, leading to slag buildup, nodules, and even incomplete cutting. High precision is required for the cutting height during the cutting process, with a positioning accuracy within 0.05mm. The thickness of metal sheets often fluctuates in the width direction. To maintain a stable cutting height, most mainstream laser heads are equipped with non-contact distance sensors that measure the distance between the laser head and the metal sheet surface. For example, a certain brand of laser head has a distance sensor measurement range of 0.0–10.0mm, corresponding to an output voltage of 0–10V. The ratio between the measured output voltage and the corresponding distance value is stored in the laser head's height adjuster, and this ratio is affected by the material being measured.

[0007] Because there is a certain error in the cutting plate width data, to ensure that the cutting plate can be completely cut, the laser and cooling gas need to be activated before the laser head reaches the edge of the cutting plate. Similarly, after the cutting plate is finished, even though the laser head has already moved beyond the other side of the cutting plate, the laser and cooling gas must remain on for a short period of time. This results in two separate processes during the cutting process: one where the laser head enters the edge of the cutting plate, and another where it exits. During both of these processes, the laser head's servo function is enabled. At these times, the sensing distance of the laser head outside the cutting plate area will exceed its measurement range. Furthermore, based on actual observation, there is a transition time of approximately two sampling cycles for the sensing distance. Taking the laser head exiting the edge of the cutting plate as an example, the sensing distance first changes from near the cutting height to a relatively large value within the measurement range, then reaches near the measurement range in the next sampling cycle, and then exceeds the measurement range in the next sampling cycle after that.

[0008] After cutting, the steel plates are transported to the next process via conveyor rollers. This next process may involve direct stacking and packaging for transport, or further processing of the steel plates. Generally, the processing speed of this next process is relatively low, while the steel plate conveying speed should be as high as possible to improve production efficiency. However, in actual production, several accidents have occurred where excessive speed caused two steel plates to collide. The experience learned is that the two steel plates should maintain a certain safe distance, moving at high speed when the distance is large, and automatically slowing down or stopping when the distance is less than the safe distance. This places high demands on the real-time positioning and tracking of the steel plate's head and tail. Summary of the Invention

[0009] The main objective of this invention is to provide an automatic control method and system for a laser cutting machine, which can improve the positioning accuracy of the entire laser cutting process.

[0010] The technical solution adopted in this invention is: an automatic control method for a laser cutting machine unit, wherein the laser cutting machine unit includes: a transmission mechanism, a cutting machine frame mounted on the transmission mechanism along the width direction of the workpiece to be cut, a servo motor unit for driving the movement of the cutting machine frame, and a length grating extending downstream of the cutting machine frame to the transmission endpoint of the transmission mechanism; wherein the transmission mechanism includes transmission rollers arranged sequentially along the transmission direction, and the transmission mechanism has a cutting start position and a cutting position, wherein the cutting start position is provided with a start photoelectric switch and a first transmission roller, the first transmission roller is provided with a transmission roller encoder, and a second transmission roller and a third transmission roller are arranged sequentially downstream of the first transmission roller, and the cutting position is located at... Between the second and third transmission rollers; the cutting machine frame is set above the cutting position, and the two ends of the cutting machine frame are driven to move along the transmission direction by the first X-axis servo motor and the second X-axis servo motor respectively. The first X-axis servo motor is equipped with an X-axis absolute encoder. The cutting machine frame is equipped with a laser head. The laser head moves along the width direction of the object to be cut by the Y-axis servo motor. The Y-axis servo motor is equipped with a Y-axis absolute encoder. The laser head moves along the height direction of the object to be cut by the Z-axis servo motor. The Z-axis servo motor is equipped with a Z-axis absolute encoder. The laser head is equipped with a laser head nozzle. The laser head nozzle is equipped with a distance sensor for judging the distance between the laser head nozzle and the object to be cut.

[0011] This method includes the following parts:

[0012] P1. Precisely position the object to be cut:

[0013] P101. When the head of the object to be cut reaches the starting photoelectric switch, the calculated distance between the head of the object to be cut and the cutting position is calculated based on the value of the transmission roller encoder.

[0014] P102. After the head of the object to be cut enters the measurement area of ​​the length grating, the first valid measurement value of the length grating is used to compensate for the calculated distance between the head of the object to be cut and the cutting position; the speed of the transmission roller is controlled according to the compensated calculated distance between the head of the object to be cut and the cutting position.

[0015] P103. When the calculated distance between the head of the object to be cut and the cutting position reaches the specified length, the transmission stops, and a short preset time is delayed to wait for the length grating measurement value to stabilize. The positioning error of the object to be cut is calculated based on the length grating measurement value, and the X-axis servo motor is used to compensate for the positioning error of the object to be cut, thereby adjusting the laser head to reach the accurate cutting position.

[0016] P2, Cutting:

[0017] P201. Record the X-axis absolute encoder reading when in the cutting position, set the laser head position limit in the X-axis direction, and control the first and second X-axis servo motors to complete the cutting positioning.

[0018] P202. Control the Y-axis servo motor to move the laser head to the cutting start point located on the edge of the object to be cut, turn on the laser and cutting gas, and the laser head moves along the Y-axis at a specified cutting speed to cut the object at a uniform speed. When the laser head moves to the cutting end point located on the other side of the object to be cut, the cutting is completed and the laser and cutting gas are turned off.

[0019] P203. After the cutting is completed, the laser head returns to the cutting starting point along the Y-axis at a speed that changes from fast to slow. The cutting starting point is equipped with a zero-point limit switch. When the zero-point limit switch shows a rising edge signal, the laser head performs automatic zero-point correction in the Y-axis direction.

[0020] P3. Calibration of the proximity sensor:

[0021] P301. Adjust the laser head focal length to zero and check the laser head status signal. Set a calibration characteristic curve according to the cutting height range. The calibration characteristic curve consists of several feature points within the measurement range. When setting the calibration characteristic curve, set denser feature points within the cutting height range of the laser cutting machine and sparser feature points outside the cutting height range. Dense and sparse are relative concepts.

[0022] P302. Control the Y-axis servo motor to move the laser head from its initial position to the top of the workpiece to be cut, and then control the Z-axis servo motor to descend until the laser head nozzle contacts the workpiece; control the Z-axis servo motor to move the laser head sequentially to each feature point on the calibration feature curve for calibration.

[0023] P303. After calibration, control the Y and Z axis servo motors to return to the initial position and filter the distance sensor measurement values.

[0024] P304. If a fault occurs during the calibration process, resolve the fault and restart the calibration.

[0025] P4, Speed ​​Control:

[0026] P401. Based on the installed photoelectric switches, the transmission mechanism is divided into segments along the transmission direction of the object to be cut. The segment between two adjacent photoelectric switches is a roller conveyor segment. Within each roller conveyor segment, the positions of the head and tail of the object to be cut are calculated, and head and tail occupancy signals are generated respectively. The last roller conveyor segment is the final roller conveyor segment, and the other roller conveyor segments are intermediate roller conveyors.

[0027] P402. Set the safe distance between the objects to be cut. When conveying the objects to be cut on the intermediate roller conveyor, set the speed of each roller conveyor segment according to the head and tail positioning signals and the actual distance between the objects to be cut.

[0028] P403. Set a speed change range in the final section of the roller conveyor. When the head of the workpiece to be cut reaches the speed change range, the final section of the roller conveyor adjusts its speed according to the allowable roller conveyor advance signal of the next process and the signal that the workpiece to be cut is entering the next process. It also monitors whether the workpiece to be cut is stuck. If the workpiece to be cut is stuck, the entire line stops.

[0029] According to the above scheme, P101 specifically refers to:

[0030] When the head of the object to be cut reaches the starting photoelectric switch, the length traveled by the object to be cut at each sampling moment is first calculated based on the value of the transmission roller encoder.

[0031] The distance between the starting photoelectric switch and the cutting position is measured and denoted as S. S，Cut Starting from the start of the calculation of the length of the object to be cut, accumulate the length S that has been traveled at each sampling time. Inc The total length traveled by the head of the object to be cut from the starting photoelectric switch is obtained and denoted as S. Accum The calculated distance S between the head of the object to be cut and the cutting position is then... Head，Cal For S Accum -S S，Cut .

[0032] According to the above scheme, P102 specifically refers to:

[0033] P102.1 Distance Compensation:

[0034] Let S be the distance from the cutting position to the starting point of the length grating. Cut，Opt , will S Cut，Opt As the starting value for length grating measurement, the length grating measures the distance between the head of the object to be cut and the cutting position. After the object to be cut enters the measurement range of the length grating, if the length grating measurement value is greater than S at a certain sampling moment... Cut，Opt Then the measurement value at this moment is determined to be valid;

[0035] Let m be the time when the first valid sampling time for the grating measurement value appears after the head of the object to be cut enters the grating measurement area; let S be the grating measurement value at time m. Optical (m), and the calculated distance S between the head of the object to be cut and the cutting position. Head，Cal The error between (m) and the error is recorded as the compensation value S. Com :

[0036] S Com =S Optical (m)-S Head，cal (m)

[0037] The calculated length of the object to be cut after compensation is set as S. Head，F ,but:

[0038] S Head，F =S Head，cal +S Com

[0039] P102.2 Calculate the deceleration distance based on the maximum speed and deceleration of the drive roller:

[0040]

[0041] In the formula, V Max A is the maximum linear velocity of the drive roller. Dec S is the deceleration of the drive roller. Dec This is the distance the drive roller needs to travel to reduce its speed from maximum to zero.

[0042] P102.3 Setting the speed of the drive roller:

[0043] Let the cutting length of the object to be cut be L. Cut Then the distance that still needs to be transmitted is:

[0044] S Left =L Cut -S Head，F

[0045] Based on the remaining transmission distance, set the transmission speed to:

[0046]

[0047] In the formula, t Dec For from S Left =S Dec The deceleration time is calculated from the start of the current moment; when the remaining transmission distance is greater than the deceleration distance, the drive roller runs at its maximum speed; when the remaining transmission distance is less than or equal to the deceleration distance, the drive roller decelerates at a speed of A. Dec Decelerate to zero.

[0048] According to the above scheme, P103 specifically refers to:

[0049] P103.1 Calculate the positioning error:

[0050] After the drive rollers decelerate to zero, wait a short time for the length grating measurement value to stabilize, read the current grating measurement value, calculate the positioning error of the workpiece to be cut, and use the grating measurement value S. Optical Calculate the positioning error S of the object to be cut Error :

[0051] S Error =L Cut -S Optical

[0052] In the formula L CutThe cutting length of the object to be cut;

[0053] P103.2 Calculate the position of the laser head in the transmission direction of the workpiece to be cut:

[0054] Taking the direction of the object to be cut as positive, the position P when the laser head moves along the X-axis to the cutting position is... Cut Then the position P of the laser head in the transmission direction of the object to be cut X，Set for:

[0055] P X，Set =P Cut -S Error

[0056] Controlling the servo motor assembly causes the laser head to move to P X，Set This enables precise positioning.

[0057] According to the above scheme, P201 specifically refers to:

[0058] The positional relationship between the cutting position and the transmission roller used for transporting the workpiece to be cut is determined. The laser head is moved along the X-axis to the cutting position by controlling the X-axis servo motor. Then, the position value of the X-axis absolute encoder is recorded as the cutting position value, denoted as P. X，Cut ;

[0059] Based on the distance between the drive rollers and the roller diameter, the range that the laser head can move back and forth along the X-axis at the cutting position is calculated, and a preset margin is left to obtain the X-axis position limit value; if the calculated cutting position setting value exceeds the X-axis position limit value, an alarm is triggered and the cutting step is stopped.

[0060] The cutting machine outlet is equipped with a length grating for collecting the distance from the head of the workpiece to the cutting position. Based on the length of the conveyed material collected by the length grating, the position setting value of the cutting position is calculated and denoted as P. X，Set Preset a small range value P on the X-axis A，X As the range of arrival, let P be... X，Act For the actual position of the cutting position, when |P X，Set -P X，Act |≤P A，X When the time indicates that the position is reached, the X-axis servo motor stops moving; if |P X，Set -P X，Act |>P A，X The proportional controller is then used to calculate the setpoint for the X-axis servo motor's movement speed and apply a limit, as shown in the following formula:

[0061] V ServoX，Set =LIM X [K P，X ×(P X，Set -P X，Act )]

[0062] In the formula, V ServoX，Set LIM sets the moving speed of the X-axis servo motors on both sides. X K represents the limiting element for the X-axis velocity. P，X This is the proportional coefficient of the X-axis proportional controller.

[0063] According to the above scheme, in P202, controlling the Y-axis servo motor to move the laser head to the cutting starting point on the edge of the object to be cut is specifically as follows:

[0064] As the laser head moves along the Y-axis to the edge of the object to be cut, the set position value of the cutting start point is based on the edge position of the object to be cut calculated according to the width data, minus twice the maximum width error.

[0065] Preset a small range of Y-axis values ​​P A，Y As the positioning range, when the difference between the actual position of the laser head on the Y-axis and the set position of the cutting starting point is outside the positioning range, the speed setting value for the first positioning on the Y-axis is calculated using the following formula:

[0066] V ServoY，Set1 =LIM Y [K P，Y ×(P Y，Set1 -P Y，Act )]

[0067] In the formula, LIM Y K represents the limiting element for the Y-axis velocity. P，Y P is the scaling factor for the Y-axis. Y，Act P represents the actual position of the laser head on the Y-axis. Y，Set1 This is the set position value of the cutting start point when the laser head is first positioned.

[0068] According to the above scheme, P401 is specifically segmented into sections for the conveyor rollers carrying the object to be cut in the following manner:

[0069] Photoelectric switches are installed at certain intervals along the conveyor belt of the object to be cut, and an identification signal is emitted when an object to be cut passes through the position of the photoelectric switch.

[0070] The transmission rollers between two adjacent photoelectric switches are grouped together, thereby dividing the entire conveyor roller track for the object to be cut into several segments. The transmission speed of the transmission rollers in each segment of the roller track changes together.

[0071] Taking the starting position of the photoelectric switch on the conveyor roller of the object to be cut as the starting point, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values;

[0072] The real-time position of the transmitted workpiece head is calculated as follows, and a head occupancy signal is generated:

[0073] Let P be the position of the photoelectric switch at the starting position of a certain roller conveyor segment X. X，Start The position of the photoelectric switch at the end of section X of the roller conveyor is P. X，End When the head of the object to be cut reaches P X，Start P X，Start The photoelectric switch at the location sends an identification signal, indicating that the head of the workpiece to be cut is positioned within the roller conveyor segment X as an occupancy signal. X，Head Set to 1; when the head of the object to be cut reaches P X，End P X，End The photoelectric switch at the location sends an identification signal, indicating that the head of the workpiece to be cut is positioned within roller section X as an occupancy signal. X，Head Reset to 0;

[0074] Occupy signal in the head X，Head Within a time interval of 1, based on the transmission speed of roller segment X, the distance the object to be cut is transmitted in roller segment X is accumulated once at each sampling moment to obtain the real-time position of the head of the object to be cut.

[0075] The method for acquiring the real-time position of the tail of the object to be cut and the tail occupancy signal is the same as that for acquiring the real-time position of the head of the object to be cut and the head occupancy signal.

[0076] According to the above scheme, P402 specifically refers to:

[0077] Mark the roller conveyor segments along the direction of the material to be cut;

[0078] 1) If there is a head-end occupancy signal on roller section X, while the tail-end occupancy signals on roller sections X+1 and X+2 are both 0, then roller section X will move at its maximum speed V. Max run;

[0079] 2) If there is a head-end occupancy signal on roller section X, a tail-end occupancy signal on roller section X+1 is 0, and a tail-end occupancy signal on roller section X+2 is 1, then calculate the distance Dis between the two pieces of material to be cut using the following formula. X，X+2 :

[0080] Dis X，X+2 =P X+2，Tail -P X，Head

[0081] P X+2，Tail P represents the tail end of the steel plate located on roller conveyor segment X+2. X，Head This refers to the head position of the workpiece to be cut, located on roller conveyor segment X.

[0082] If Dis X，X+2 >D Safe Then the roller conveyor segment X travels at its maximum speed V. Max Run; D Safe To maintain a safe distance;

[0083] If Dis X，X+2 <D Safe And if the transmission speed of roller conveyor segment X+2 is 0.0, then the speed of roller conveyor segment X is set to 0.0;

[0084] If Dis X，X+2 <D Safe Furthermore, the transmission speed of roller conveyor segment X+2 is the preset low speed V. Low Then the speed of roller section X is set to V. LOw ;

[0085] 3) If there is a head occupancy signal on roller section X, and a tail occupancy signal on roller section X+1 is 1, then set the speed of roller section X to 0.0.

[0086] According to the above scheme, the gear shift adjustment in P403 is specifically as follows:

[0087] 1) If the head of the workpiece to be cut has not yet reached the speed change position, and the steel plate is entering the next process, the signal switch will be activated. Next If the value is 0, then the final roller conveyor will operate at its highest speed V. Max run;

[0088] 2) When the head of the workpiece to be cut enters the speed change zone, if the steel plate is entering the next process, the signal switch will be activated. Next =0, and the allowable roller advance signal for the next process is Allow. Next =1, then the speed V of the next process on the last roller conveyor is... Next Run; if Switch Next =0 and Allow Next =0, then set the speed of the last roller conveyor to 0.0, and wait for Allow. Next After changing to 1, the speed of the final roller conveyor is set to V. Next ;

[0089] 3) When the head of the object being cut enters the speed shift zone, if Switch Next =1, then the speed of the last section of the roller conveyor is set to 0.0;

[0090] Monitor for plate jamming; if a plate jams, the entire line will stop. Specifically:

[0091] The timer is started when the signal for the workpiece to be cut changes from 0 to 1 as it enters the next process. The timer is reset when the signal for the steel plate to enter the next process changes from 1 to 0, and the timer's duration T is obtained.Next ;

[0092] Calculate the theoretical transmission time T Trans :T Trans =L Plate / V next In the formula L Plate V represents the length of the object to be cut. Next For the speed of the next process;

[0093] If T Next >T Trans +T1, where T1 is a preset time interval, immediately triggers a full-line stop signal, and all roller conveyors stop immediately, waiting for operators to handle the fault.

[0094] An automatic control system for a laser cutting machine unit includes a control unit and a frequency converter. The control unit is used to execute the automatic control method of the laser cutting machine unit, and sends the speed set value of each roller conveyor segment to the frequency converter, which then sends it to the drive rollers of each roller conveyor segment.

[0095] The beneficial effects of this invention are: it realizes full automation and intelligence of the entire laser cutting process, achieves precise positioning of the workpiece to be cut and high-precision cutting positioning, solves the problem of cumulative error generated by the Y-axis servo motor, solves the problem of controlling the cutting height during the cutting process, balances the production efficiency and safety of the roller conveyor process, achieves a smooth transition to the next process, reduces the labor intensity of workers, and improves production efficiency. Attached Figure Description

[0096] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0097] Figure 1 This is a flowchart of a method according to an embodiment of the present invention.

[0098] Figure 2 This is a top view schematic diagram of a laser cutting unit structure according to an embodiment of the present invention.

[0099] Figure 3 This is a left-side view of a laser cutting unit structure according to an embodiment of the present invention.

[0100] In the diagram: 1-PLC controller, 2-servo amplifier, 3-frequency converter, 4-drive roller encoder, 5-first X-axis servo motor, 6-X-axis absolute encoder, 7-first X-axis servo motor running track, 8-first drive roller, 9-workpiece to be cut, 10-second drive roller, 11-third drive roller, 12-cutting machine frame, 13-Y-axis servo motor running track, 14-start photoelectric switch, 15-laser head, 16-Y-axis servo motor, 17-Y-axis absolute encoder, 18-length grating, 19-Y-axis zero-point limit switch, 20-second X-axis servo motor, 21-second X-axis servo motor running track, 22-Z-axis servo motor running track, 23-laser, 24-height adjuster, 25-Z-axis servo motor, 26-Z-axis absolute encoder, 27-laser head nozzle, 28-distance sensor. Detailed Implementation

[0101] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0102] This embodiment addresses a steel plate as the material to be cut, but it can also be other sheet-like materials that need to be cut, such as metal sheets.

[0103] Laser cutting unit such as Figure 2 and Figure 3As shown, the device includes: a transmission mechanism; a cutting machine frame 12 mounted on the transmission mechanism along the width direction of the workpiece 9 to be cut; a servo motor assembly for driving the cutting machine frame 12 to move; and a length grating 18 extending downstream of the cutting machine frame 12 to the transmission endpoint of the transmission mechanism. The transmission mechanism includes drive rollers arranged sequentially along the transmission direction. The transmission mechanism has a cutting start position and a cutting position. The cutting start position is equipped with a start photoelectric switch 14 and a first drive roller 8. The first drive roller 8 is equipped with a drive roller encoder 4. Downstream of the first drive roller 8, a second drive roller 10 and a third drive roller 11 are arranged sequentially. The cutting position is located between the second and third drive rollers 10 and 11. The cutting machine frame 12 is positioned at the cutting position. The two ends of the cutting machine frame 12 are driven to move along the transmission direction by the first X-axis servo motor 5 and the second X-axis servo motor 20 respectively. The first X-axis servo motor 5 is equipped with an X-axis absolute encoder 6. The cutting machine frame 12 is equipped with a laser head 15. The laser head 15 moves along the width 9 degrees of the workpiece to be cut by the Y-axis servo motor 16. The Y-axis servo motor 16 is equipped with a Y-axis absolute encoder 17. The laser head 15 moves along the height 9 of the workpiece to be cut by the Z-axis servo motor 25. The Z-axis servo motor 25 is equipped with a Z-axis absolute encoder 26. The laser head 15 is equipped with a laser head nozzle 27. The laser head nozzle 27 is equipped with a distance sensor 28 for determining the distance between the laser head nozzle 17 and the workpiece to be cut 9. The first X-axis servo motor 5 and the second X-axis servo motor 20 move along the first X-axis servo motor running track 7 and the second X-axis servo motor running track 21, respectively. The Y-axis servo motor 16 moves along the Y-axis servo motor running track 13, and the Z-axis servo motor 25 moves along the Z-axis servo motor running track 22. The Y-axis zero-point limit switch 19 is used for zero-point calibration of the Y-axis servo motor 16. The laser head is also equipped with a height adjuster 24.

[0104] This invention provides an automatic control system for a laser cutting machine. The system includes a control unit and a frequency converter 3. The control unit executes the automatic control method for the laser cutting machine described below, sending the speed setpoint for each roller conveyor segment to the frequency converter 3, which then sends the setpoint to the drive rollers of each roller conveyor segment. In this embodiment, the control unit is a PLC controller 1. When controlling servo motors, the PLC controller 1 is connected to each servo motor via a servo amplifier 2.

[0105] This invention provides an automatic control method for a laser cutting unit, such as... Figure 1 As shown, it includes the following parts:

[0106] P1. Precisely position the object to be cut (9):

[0107] P101, starting when the head of the object to be cut 9 reaches the starting photoelectric switch 14, the calculated distance between the head of the object to be cut 9 and the cutting position is calculated based on the value of the transmission roller encoder 4; P101 specifically means:

[0108] When the head of the object to be cut 9 reaches the starting photoelectric switch 14, the length traveled by the object to be cut 9 at each sampling moment is first calculated based on the value of the transmission roller encoder 4; specifically:

[0109] When the head of the workpiece 9 reaches the starting photoelectric switch 14, a rising edge signal from the starting photoelectric switch 14 is received, denoted as P. Start , used to initiate the calculation of the walking length of the object to be cut;

[0110] Based on the reading of the drive roller encoder 4 at the starting point of the cutting area, calculate the length traveled by the object to be cut 9 at each sampling moment;

[0111] If P Encoder (n)>P Encoder (n-1), then:

[0112] S Inc (n)=π×D drv ×[P Encoder (n)-P Encoder [(n-1)] / P Max

[0113] If P Encoder (n) <P Encoder (n-1), then:

[0114] S Inc (n)=π×D drv ×[P Encoder (n)+P Max -P Encoder [(n-1)] / P Max

[0115] In the formula, S Inc (n) represents the length that the object to be cut 9 has traveled at the current moment, D drv P is the diameter of the drive roller. Encoder (n) and P Encoder (n-1) represent the readings of the drive roller encoder 4 at the current time and the previous sampling time, respectively, P Max The change in the reading of encoder 4 is the amount of time required for the drive roller to rotate one revolution.

[0116] The distance between the starting photoelectric switch 14 and the cutting position is measured and denoted as S. S，Cut Starting from the start of the calculation of the transmission length of the object to be cut 9, the length S traversed at each sampling time is accumulated. IncThe total length traveled by the head of the object to be cut 9 from the starting photoelectric switch 14 is obtained and denoted as S. Accum The calculated distance S between the head of the object to be cut 9 and the cutting position is then... Head，Cal For S Accum -S S，Cut .

[0117] The cutting position is set at the exact center of the nearest upstream and downstream drive rollers. The distance between the starting photoelectric switch 14 and the cutting position is measured and denoted as S. S，Cut Starting from the start of the calculation of the transmission length of the object to be cut 9, the length S traversed at each sampling time is accumulated. Inc The total length traveled by the head of the object to be cut 9 from the starting photoelectric switch 14 is obtained and denoted as S. Accum The calculated distance S between the head of the object to be cut 9 and the cutting position is then... Head，cal For S Accum -S S，Cut .

[0118] P102. After the head of the workpiece to be cut enters the measurement area of ​​the length grating, the first valid measurement value of the length grating is used to compensate for the calculated distance between the head of the workpiece and the cutting position; the speed of the transmission roller is controlled according to the compensated calculated distance between the head of the workpiece and the cutting position. Specifically:

[0119] P102.1 Distance Compensation:

[0120] Let S be the distance from the cutting position to the starting point of the length grating. Cut，Opt , will S Cut，Opt As the starting value for length grating measurement, the length grating measures the distance between the head of the object to be cut and the cutting position. After the object to be cut enters the measurement range of the length grating, if the length grating measurement value is greater than S at a certain sampling moment... Cut，Opt Then the measurement value at this moment is determined to be valid;

[0121] Let m be the time when the first valid sampling time for the grating measurement value appears after the head of the object to be cut enters the grating measurement area; let S be the grating measurement value at time m. Optical (m), and the calculated distance S between the head of the object to be cut 9 and the cutting position. Head，Cal The error between (m) and the error is recorded as the compensation value S. Com :

[0122] S Com =S Optical (m)-S Head，Cal (m)

[0123] The calculated length of the object to be cut after compensation is set as S. Head，F， but:

[0124] S Head，F =S Head，cal +S Com

[0125] P102.2 Calculate the deceleration distance based on the maximum speed and deceleration of the drive roller:

[0126]

[0127] In the formula, V Max A is the maximum linear velocity of the drive roller. Dec S is the deceleration of the drive roller. Dec This is the distance the drive roller needs to travel to reduce its speed from maximum to zero.

[0128] P102.3 Setting the speed of the drive roller:

[0129] Let the cutting length of the object to be cut be L. Cut Then the distance that still needs to be transmitted is:

[0130] S Left =L Cut -S Head，F

[0131] Based on the remaining transmission distance, set the transmission speed to:

[0132]

[0133] In the formula, t Dec For from S Left =S Dec The deceleration time is calculated from the start of the current moment; when the remaining transmission distance is greater than the deceleration distance, the drive roller runs at its maximum speed; when the remaining transmission distance is less than or equal to the deceleration distance, the drive roller decelerates at a speed of A. Dec Decelerate to zero.

[0134] P103. When the calculated distance between the head of the object to be cut and the cutting position reaches the specified length, transmission stops, and a short preset time is allowed to allow the length grating measurement value to stabilize. The positioning error of the object to be cut is calculated based on the length grating measurement value, and the X-axis servo motor is used to compensate for this error, thereby adjusting the laser head to the accurate cutting position. Specifically:

[0135] P103.1 Calculate the positioning error:

[0136] After the drive rollers decelerate to zero, wait a short time for the length grating 18 measurement value to stabilize. Then, read the current grating measurement value and calculate the positioning error of the workpiece to be cut. Use the grating measurement value S... Optical Calculate the positioning error S of the object to be cut Error :

[0137] S Error =L Cut -S Optical

[0138] In the formula L Cut The cutting length of the object to be cut (9);

[0139] P103.2 Calculate the position of laser head 15 in the transmission direction of the object to be cut:

[0140] Taking the forward direction of the object to be cut 9 as positive, the position of the laser head 15 when it moves along the X-axis to the cutting position is P. Cut Then the position P of the laser head 15 in the transmission direction of the workpiece 9 to be cut is... X，Set for:

[0141] P X，Set =P Cut -S Error

[0142] Controlling the servo motor assembly causes the laser head to move to P X，Set This enables precise positioning.

[0143] P2, Cutting:

[0144] P201: Record the X-axis absolute encoder reading when in the cutting position, set the laser head's position limit in the X-axis direction, and control the first and second X-axis servo motors to complete the cutting positioning. Specifically, P201 involves:

[0145] The positional relationship between the cutting position and the transmission roller used for transporting the workpiece to be cut is determined. The laser head is moved along the X-axis to the cutting position by controlling the X-axis servo motor. Then, the position value of the X-axis absolute encoder is recorded as the cutting position value, denoted as P. X，Cut ;

[0146] Based on the distance between the drive rollers and the roller diameter, the range in which the laser head can move back and forth along the X-axis at the cutting position is calculated, and a preset margin is left to obtain the X-axis position limit value; if the calculated cutting position setting value exceeds the X-axis position limit value, an alarm is triggered and the cutting step is stopped.

[0147] In this embodiment, the distance between the front drive roller 7 and the rear drive roller 8 is 550mm, and the roller diameter is 180mm. The cutting position is located exactly in the middle of the two. Therefore, the roller can only move within a range of 185mm forward and backward along the X-axis from the cutting position. If it exceeds this range, the laser will cut the drive roller, causing equipment damage. Considering leaving a certain margin, the final set range of the X-axis movement is P. X，Cut Within ±130mm.

[0148] The cutting machine outlet is equipped with a length grating for collecting the distance from the head of the workpiece to the cutting position. Based on the length of the conveyed material collected by the length grating, the position setting value of the cutting position is calculated and denoted as P. X，Set Preset a small range value P on the X-axis A，X As the range of arrival, let P be... X，Act For the actual position of the cutting position, when |P X，Set -P X，Act |≤P A，X When the time indicates that the position is reached, the X-axis servo motor stops moving; if |P X，Set -P X，Act |>P A，X The proportional controller is then used to calculate the setpoint for the X-axis servo motor's movement speed and apply a limit, as shown in the following formula:

[0149] V ServoX，Set =LIM X [K P，X ×(P X，Set -P X，Act )]

[0150] In the formula, V ServoX，Set LIM sets the moving speed of the X-axis servo motors on both sides. X K represents the limiting element for the X-axis velocity. P，X This is the proportional coefficient of the X-axis proportional controller.

[0151] In this embodiment, the speed limit range of the X-axis servo motor is 0.0 to 50.0 mm / s, and the proportional coefficient K P，X =1.15. If |P X，Set -P X，Act If the value is large, the movement speed will be at its upper limit. As the speed approaches the set position, it will gradually decrease until it enters the positioning range, at which point the X-axis servo motor will stop.

[0152] P202. Control the Y-axis servo motor to move the laser head to the cutting start point located at the edge of the object to be cut. Turn on the laser and cutting gas. The laser head moves along the Y-axis at a specified cutting speed to cut the object uniformly. When the laser head moves to the cutting end point located on the other side of the object, the cutting is completed, and the laser and cutting gas are turned off. In P202, controlling the Y-axis servo motor to move the laser head to the cutting start point at the edge of the object to be cut is specifically as follows:

[0153] Because the width data of the steel plate has a certain margin of error, the position of the edge of the object to be cut 9 calculated based on the width data may not match the actual position. To ensure complete cutting of the object 9, during the process of the laser head moving along the Y-axis to the edge of the object 9, the set position value of the cutting starting point is based on the edge position of the object 9 calculated based on the width data, minus twice the maximum width error. In this embodiment, the position of the operating side edge of the object 9 calculated based on the width data is set as P. Y，OS The maximum error value for the width data is 40.0mm, so the initial positioning setting value for the Y-axis is P. Y，Set1 =P Y，OS -80.0mm.

[0154] Preset a small range of Y-axis values ​​P A，Y As the positioning range, when the difference between the actual position of the laser head on the Y-axis and the set position of the cutting starting point is outside the positioning range, the speed setting value for the first positioning on the Y-axis is calculated using the following formula:

[0155] V ServoY，Set1 =LIM Y [K P，Y ×(P Y，Set1 -P Y，Act )]

[0156] In the formula, LIM Y K represents the limiting element for the Y-axis velocity. P，Y P is the scaling factor for the Y-axis. Y，Act P represents the actual position of the laser head on the Y-axis. Y，Set1 This is the set position value of the cutting start point during the initial positioning of the laser head. In this embodiment, the range of the Y-axis is P. A，Y =0.1mm, the speed limit range of the Y-axis servo motor is 0.0~250.0mm / s, and the proportional coefficient K P，Y =2.0.

[0157] Before cutting, it is necessary to power on the laser, water chiller, laser head, and other laser-related equipment. The valve of the cutting gas cylinder must also be opened, and the laser must be allowed to reach its operating temperature range. Cutting can only begin once all laser-related equipment is fully started and ready for laser emission. Once all laser-related equipment is ready and the laser head has been initially positioned along the Y-axis (reaching P... Y，Set1 First, turn on the cutting gas (the cutting gas cools the laser head and assists in cutting). After the cutting gas starts for 1 second, start the laser to emit light. The laser is emitted from the laser head nozzle and begins to cut the object to be cut.

[0158] Simultaneously with the activation of the cutting gas, the Y-axis servo motor operates at a specified cutting speed V. Cutting Move from the operating side of the workpiece 9 to the transmission side, that is:

[0159] V ServoY，set2 =V Cutting

[0160] In the formula, V ServoY，Set2 This is the speed setting for uniform movement (cutting) along the Y-axis. The position of the transmission side edge of the workpiece 9, calculated based on the width data, is set as P. Y，DS The position setting after the Y-axis cutting is completed is P. Y，DS Adding twice the maximum width error, in this embodiment, the position setting value for the Y-axis cutting process is P. Y，Set2 =P Y，DS +80.0mm. When the laser head reaches the set value at its actual position on the Y-axis, it decelerates to zero and the laser is turned off. Wait 1 second after the laser is turned off before turning off the cutting gas.

[0161] P203. After cutting, the laser head returns to the cutting starting point along the Y-axis at a speed that changes from fast to slow. A Y-axis zero-point limit switch 19 is installed at the cutting starting point. When the zero-point limit switch generates a rising edge signal, automatic zero-point calibration of the laser head in the Y-axis direction is performed. The actual position of the laser head on the Y-axis is measured by a Y-axis absolute encoder. Using the zero-point limit switch on the operating side as the cutting starting point, the laser head moves towards the transmission side, with the position value gradually increasing. After cutting, the Y-axis needs to return to the cutting starting point from the transmission side, awaiting the next cut.

[0162] Specifically:

[0163] After cutting is completed, the Y-axis servo motor is controlled to move towards the cutting starting point at a preset high speed, while the acceleration is also set to a preset high value; specifically, in this embodiment, when the actual position of the laser head on the Y-axis is greater than or equal to 200.0 mm, V is set... ServoY，Set3 =250mm / s, A Acc =A Dec =500mm / s 2 Among them, A Acc For the acceleration setpoint, A Dec This is the deceleration setting value.

[0164] When the laser head moves close to the cutting start point, the operating speed is reduced, with the deceleration set to a preset low value, operating at a medium speed. Specifically, in this embodiment, when the actual position of the laser head on the Y-axis is between 20.0mm and 200.0mm, V ServoY，Set3 =80mm / s, A Acc =A Dec =300mm / s 2 .

[0165] When the laser head moves to a certain small range from the cutting start point, it moves towards the cutting start point at a preset slow speed. For example, in this embodiment, when the actual position of the Y-axis is less than 20.0mm, the V-axis is set... ServoY，Set3 =10mm / s, A Acc =A Dec =500mm / s 2 .

[0166] When the zero-point limit switch generates a rising edge signal, it indicates that the laser head has moved to the cutting start point. The current reading of the Y-axis absolute encoder is recorded and used as the new cutting start point position value. Simultaneously, the speed of the Y-axis servo motor is set to zero, and the deceleration is set to a preset high value to bring the Y-axis servo motor to a stop as quickly as possible. Specifically, V... ServoY，Set3 =0.0mm / s, A Acc =A Dec =500mm / s 2 This way, the Y-axis will automatically be corrected after each cut, preventing cumulative errors.

[0167] P3. Calibration of the proximity sensor:

[0168] P301. Adjust the laser head focal length to zero and check the laser head status signal. Set a calibration characteristic curve according to the cutting height range. The calibration characteristic curve consists of several feature points within the measurement range. When setting the calibration characteristic curve, set denser feature points within the cutting height range of the laser cutting machine and sparser feature points outside the cutting height range. Dense and sparse are relative concepts.

[0169] Before calibrating the distance sensor, the laser head's focal length must be adjusted to zero to avoid calibration deviations. In this embodiment, an autofocus laser head is used; simply setting the focal length to zero and issuing a focus command completes the process. For a manual focus laser head, the focal length must be manually adjusted to zero.

[0170] Calibration can only be performed when the laser head is functioning correctly. Various status signals of the laser head are checked in the PLC. These status signals are transmitted to the PLC via hardwiring or communication. In this embodiment, the laser head status signals are transmitted to the PLC via hardwiring. Specifically, the following signals need to be checked: the laser head nozzle is not in contact with the steel plate; the side of the laser head is not in contact with the steel plate; the laser head focal length is at zero; the laser head nozzle is detectable; the laser head wiring is normal; and the distance between the laser head and the steel plate is greater than the measurement range. Calibration can only be performed if all of the above conditions are met.

[0171] In this embodiment, the distance sensor's measurement range is 0.0–10.0 mm. To achieve high-precision calibration, a calibration method using 16 feature points is employed within the measurement range, and these 16 feature points form a characteristic curve. Considering that the cutting height of a laser cutting machine is typically within 2.0 mm, more feature points are set below 2.0 mm, while the feature points in the 2.0 mm–10.0 mm range are sparsely distributed. In this embodiment, the selected feature points are:

[0172] [0.2, 0.5, 0.7, 1.0, 1.2, 1.5, 1.8, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 10.0]mm

[0173] P302. Control the Y-axis servo motor to move the laser head from its initial position to the top of the workpiece to be cut, and then control the Z-axis servo motor to descend until the laser head nozzle contacts the workpiece; control the Z-axis servo motor to move the laser head sequentially to each feature point on the calibration feature curve for calibration.

[0174] Because different steel grades affect the sensing distance value, the distance sensor calibration is mainly used to adapt to different steel grades. This requires the laser head to be positioned above the steel plate during calibration. Therefore, the laser head must first be moved to the top of the steel plate. Next, the zero value of the sensing distance needs to be determined, so the Z-axis servo motor is controlled to bring the laser head nozzle into contact with the steel plate. Then, the Z-axis servo motor is controlled to move to each feature point on the calibration characteristic curve.

[0175] P302.1 Control the Y-axis servo motor to move the laser head to the upper part of the steel plate;

[0176] Control the Y-axis servo motor to move the laser head from its initial position to a certain distance inside the edge of the steel plate. Let the middle position of the roller conveyor be Y. Center The width of the steel plate is S width To ensure the laser head is positioned above the steel plate, it needs to be moved a certain distance inward from the edge of the steel plate. in In this embodiment, this distance is set to D. in =150.0mm, then the position setting value of the Y-axis servo motor is:

[0177]

[0178] Moving the Y-axis servo motor to the set position ensures that the laser head is positioned on the top of the steel plate.

[0179] P302.2 Control the Z-axis servo motor to descend until the laser head nozzle contacts the steel plate.

[0180] Adjust the Z-axis servo motor to rapidly lower the laser head from its initial position into the measurement range of the distance sensor. In this embodiment, the distance sensor's measurement range is 0.0–10.0 mm. To ensure the laser head descends into the measurement range, the target position of the Z-axis servo motor is set to 8.0 mm from the steel plate. The Z-axis descent speed is set to 10.0 mm / s.

[0181] Once in position, the Z-axis continues to descend very slowly to avoid damaging the laser head nozzle, for example, set to 0.5 mm / s, until the laser head returns and the nozzle contacts the steel plate, at which point the signal stops. The laser head height adjuster records the induced voltage value at this point as the zero value of the sensing distance.

[0182] P302.3 Control the Z-axis servo motor to move the laser head sequentially to each feature point on the calibration feature curve.

[0183] The Z-axis servo motor is controlled to raise the laser head to the feature point at the maximum distance from the steel plate, i.e., 10.0 mm away. This is the first feature point for calibration. After reaching the target position, there is a 2-second delay to allow the height adjuster to record the position and corresponding voltage value. Then, the Z-axis servo motor is controlled to move from high to low according to the calibration feature curve, reaching each feature point from a specified distance. After each point reaches a specified distance, there is a 2-second delay to allow the height adjuster to record the position and corresponding voltage value, until all feature points on the calibration feature curve are reached.

[0184] P303. After calibration, control the Y and Z axis servo motors to return to their initial positions and filter the distance sensor measurement values.

[0185] After calibrating all feature points, the Y-axis and Z-axis servo motors need to be controlled to return to their initial positions. The initial position is generally defined as the zero position of the Y-axis and Z-axis absolute encoders. To save time, the motors should initially run at high speed, but the speed should be gradually reduced as they approach the initial position to accurately stop at it. To reduce the impact of external interference on the distance sensor's measurements, the measured values ​​need to be filtered.

[0186] P303.1 Use a proportional controller to control the Y-axis and Z-axis servo motors to return to their initial positions;

[0187] Calculate the speed setpoints for the Y-axis and Z-axis servo motors to return to zero using a proportional controller:

[0188] S Y，SP =Lim(K Y ×Y Act )

[0189] S Z，SP =Lim(K Z ×Z Act )

[0190] In the formula, SY，SP and S Z，SP These are the speed settings for returning to zero on the Y and Z axes, respectively, K. Y and K Z These are the proportional coefficients for the Y-axis and Z-axis proportional controllers, respectively. Act and Z Act These are the actual position values ​​measured by the absolute encoders on the Y and Z axes, respectively. Lim represents the limiting element, which restricts the speed setting within a given maximum value range. In this embodiment, the maximum speed of the Y-axis is set to 250 mm / s, and the maximum speed of the Z-axis is set to 35 mm / s. Thus, the Y and Z axes will operate at their maximum speeds during the initial stage of homing until they approach zero. After approaching zero, the speeds will gradually decrease, eventually stopping precisely and smoothly at zero.

[0191] P303.2 Filter the distance sensor measurement values.

[0192] After calibrating all feature points, the distance sensor can output the sensed distance value. However, in actual use, the distance sensor is affected by interference factors such as dust and fog in the environment. To reduce the impact of interference, the sensed distance value needs to be filtered. Commonly used filtering methods include first-order smoothing filtering and multi-point averaging filtering. One filtering method can be selected to filter the sensed distance value before outputting it. In this embodiment, multi-point averaging filtering is used, that is, several adjacent sample values ​​are selected, averaged, and then output.

[0193] P304. If a fault occurs during the calibration process, resolve the fault and restart the calibration.

[0194] In the actual calibration process, some malfunctions are inevitable. When a malfunction occurs, it is necessary to take appropriate measures and restart the calibration.

[0195] P304.1. Handling when calibration fails to start for an extended period of time.

[0196] If the servo motor does not move for an extended period after a calibration command is issued, this indicates a calibration failure. This failure is generally caused by the failure to meet necessary calibration conditions. Therefore, it is necessary to check whether these conditions are met. Specifically, in this embodiment, the following conditions need to be checked: the laser head nozzle is not in contact with the steel plate; the side of the laser head is not in contact with the steel plate; the laser head nozzle is detectable; the laser head wiring is normal; and the distance between the laser head and the steel plate is greater than the measurement range.

[0197] Once all the above conditions are met, restart the calibration.

[0198] P304.2. Handling when a no-contact-plate signal fault occurs.

[0199] After calibration begins, the first step is to determine the zero point of the distance sensor. At this point, the laser head nozzle will contact the steel plate. Normally, when the nozzle contacts the steel plate, the PLC will receive a contact signal, and the Z-axis servo motor will stop descending. However, in practice, there have been instances where the nozzle has contacted the steel plate but the PLC has not received a contact signal. In such cases, it is necessary to check the laser head nozzle, ceramic body, and protective lens for damage. If any issues are found, replace the affected parts and then perform calibration again.

[0200] P304.3. Handling when a contact plate malfunction occurs during calibration.

[0201] During calibration, the laser head gradually approaches the steel plate from the feature point furthest away. Generally, the last two feature points are very close to the plate, at which point a contact failure may occur. Specifically, a signal indicating that the nozzle has touched the steel plate appears at the last two feature points, causing the calibration to stop and report an error. If this failure occurs only occasionally, the Z-axis servo motor can be manually raised until the laser head is more than 10mm away from the steel plate, and then calibration can be restarted. If this failure occurs frequently, the descent speed of the Z-axis servo motor during calibration should be reduced, and then calibration should be restarted.

[0202] Adjust the Y-axis and Z-axis servo motors according to the above steps, move the laser head to each feature point on the calibration feature curve, and then return to the initial position. If a fault occurs, handle it separately. This completes the calibration method for the laser head distance sensor.

[0203] In summary, the calibration of the distance sensor described in this invention involves first adjusting the laser head focal length to zero and checking the laser head status signal, then setting a suitable calibration characteristic curve based on the cutting height range. Next, the Y-axis servo motor is adjusted to move the laser head to the upper part of the steel plate, and then the Z-axis servo motor is adjusted to first bring the laser head nozzle into contact with the steel plate, and then move it to each feature point on the calibration characteristic curve. Finally, a proportional controller is used to return the Y-axis and Z-axis servo motors to their initial positions, and the measured distance values ​​are filtered. Finally, a method for handling faults during the calibration process is provided. This completes the calibration method for this laser head distance sensor.

[0204] P4, Speed ​​Control:

[0205] P401. Based on the installed photoelectric switches, the transmission mechanism is segmented along the direction of the workpiece to be cut. Each segment is separated by two adjacent photoelectric switches. Within each segment, the positions of the head and tail of the workpiece to be cut are calculated, and head and tail positioning signals are generated respectively. The last segment is the final segment, and the other segments are intermediate segments. Specifically, P401 segments the workpiece transmission rollers as follows:

[0206] Photoelectric switches are installed at certain intervals along the conveyor belt of the object to be cut, and an identification signal is emitted when an object to be cut passes through the position of the photoelectric switch.

[0207] The transmission rollers between two adjacent photoelectric switches are grouped together, thereby dividing the entire conveyor roller track for the object to be cut into several segments. The transmission speed of the transmission rollers in each segment of the roller track changes together.

[0208] Starting from the position of the initial photoelectric switch on the conveyor roller of the work to be cut, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values.

[0209] In this embodiment, when the head of the object to be cut reaches the location of the photoelectric switch, a rising edge signal is emitted. The signal remains high as the steel plate passes by until the tail of the object to be cut reaches the location of the photoelectric switch, at which point a falling edge signal is emitted. Then, the signal remains low as no steel plate passes by.

[0210] The real-time position of the transmitted workpiece head is calculated as follows, and a head occupancy signal is generated:

[0211] Let P be the position of the photoelectric switch at the starting position of a certain roller conveyor segment X. X，Start The position of the photoelectric switch at the end of section X of the roller conveyor is P. X，End When the head of the object to be cut reaches P X，Start P X，Start The photoelectric switch at the location emits an identification signal (in this embodiment, the photoelectric switch emits a rising edge signal) to indicate that the head of the workpiece to be cut is located within the roller conveyor segment X, triggering the occupancy signal Occupy. X，Head Set to 1; when the head of the object to be cut reaches P X，End P X，End The photoelectric switch at the location emits an identification signal (in this embodiment, the photoelectric switch emits a rising edge signal) to indicate that the head of the workpiece to be cut is located within the roller section X, triggering the occupancy signal Occupy. X，Head Reset to 0;

[0212] Occupy signal in the head X，Head Within a time interval of 1, based on the transmission speed of roller segment X, the distance the object to be cut is transmitted in roller segment X is accumulated once at each sampling moment to obtain the real-time position of the head of the object to be cut.

[0213] Suppose that the actual rotational speed of the drive roller in a certain section X of the roller conveyor is N. X，acr Due to interference from the on-site environment, the rotational speed fluctuates significantly. Therefore, a dynamic averaging method is used to reduce the impact of interference. The conveying speed of roller conveyor segment X is obtained as follows: Roller conveyor segment X has rollers with a diameter of Dia. XThe transmission roller is used to calculate the average rotational speed of the transmission roller at several adjacent sampling times as the actual rotational speed of the transmission roller at the current moment, and then converted into the transmission speed of the roller conveyor segment X. In this embodiment, the average value of 5 adjacent sampling times is used.

[0214] 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

[0215] In the formula, n represents the current time, n-1 represents the previous time, and so on.

[0216] The formula for calculating the real-time position of the head of the object to be cut is as follows:

[0217] P X，Head =P X，Start +∑N X ·π·Dia X ·T S / G X

[0218] In the formula, P X，Head N represents the real-time position of the head of the object to be cut. X Dia represents the average rotational speed of the drive roller. X T is the diameter of the drive roller. S G is the sampling period of the PLC. X This refers to the reduction ratio of the drive roller motor.

[0219] The method for acquiring the real-time position of the tail of the workpiece to be cut and the tail occupancy signal is the same as that for acquiring the real-time position of the head of the workpiece to be cut and the head occupancy signal. Specifically:

[0220] Let P be the position of the photoelectric switch at the starting position of a certain roller conveyor segment X. X，Start The position of the photoelectric switch at the end of section X of the roller conveyor is P. X，End When the tail of the object to be cut reaches P X，Start P X，Start The photoelectric switch at the location emits an identification signal (in this embodiment, the photoelectric switch emits a falling edge signal) to indicate that the tail of the workpiece to be cut is located within the roller conveyor segment X, triggering the occupancy signal Occupy. X，Head Set to 1; when the tail of the object to be cut reaches P X，End P X，End The photoelectric switch at the location emits an identification signal (in this embodiment, the photoelectric switch emits a falling edge signal) to indicate that the tail of the workpiece to be cut is located within the roller section X, triggering the occupancy signal Occupy.X，Head Reset to 0;

[0221] Occupy, a placeholder signal at the tail X，Head Within a time interval of 1, based on the transmission speed of roller segment X, the distance the object to be cut travels in roller segment X is accumulated once at each sampling moment to obtain the real-time position of the tail of the object to be cut.

[0222] P402. Set the safety distance between the objects to be cut. When conveying the objects to be cut on the intermediate roller conveyor, set the speed of each roller conveyor segment according to the head and tail positioning signals and the actual distance between the objects to be cut. To prevent two objects to be cut from colliding on the roller conveyor, a certain distance needs to be maintained between two adjacent objects to be cut; 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, it will pose a safety hazard. Here, the safety distance should be slightly larger than the length of one segment of the roller conveyor. If the segment lengths are inconsistent, it needs to be slightly larger than the length of the longest segment of the roller conveyor. In this embodiment, the length of the longest segment of the roller conveyor is 4.95m, therefore, the safety distance D is set... Safe =5.0m. The specific steps are as follows:

[0223] Mark the roller conveyor sections along the direction of the material to be cut; when the material to be cut is running on the conveyor roller conveyor, the distance between the two materials to be cut can be calculated based on the occupancy signal and the head and tail positions, and the speed of this section of the roller conveyor can be adjusted according to the size of the distance.

[0224] 1) If there is a head-end occupancy signal on roller section X, while the tail-end occupancy signals on roller sections X+1 and X+2 are both 0, this indicates that the gap between the two pieces of material to be cut is too large. In this case, roller section X will cut at its maximum speed V. Max run;

[0225] 2) If there is a head-end occupancy signal on roller section X, a tail-end occupancy signal on roller section X+1 is 0, and a tail-end occupancy signal on roller section X+2 is 1, then calculate the distance Dis between the two pieces of material to be cut using the following formula. X，X+2 :

[0226] Dis X，X+2 =P X+2，Tail -P X，Head

[0227] P X+2，Tail P represents the tail end of the steel plate located on roller conveyor segment X+2. X，Head This refers to the head position of the workpiece to be cut, located on roller conveyor segment X.

[0228] If Dis X，X+2 >D Safe Then the roller conveyor segment X travels at its maximum speed V. Max Run; DSafe To maintain a safe distance;

[0229] If Dis X，X+2 <D Safe And if the transmission speed of roller conveyor segment X+2 is 0.0, then the speed of roller conveyor segment X is set to 0.0;

[0230] If Dis X，x +2 <D Safe Furthermore, the transmission speed of roller conveyor segment X+2 is the preset low speed V. Low Then the speed of roller section X is set to V. Low ;

[0231] 3) If there is a head occupancy signal on roller section X, and a tail occupancy signal on roller section X+1 is 1, then set the speed of roller section X to 0.0.

[0232] P403. A speed change interval is set in the final roller conveyor. When the head of the workpiece to be cut reaches the speed change interval, the final roller conveyor adjusts its speed according to the allowable roller conveyor advance signal for the next process and the signal that the workpiece is entering the next process. It also monitors whether the workpiece is stuck. If the workpiece is stuck, the entire line stops. The final roller conveyor is used to transport the steel plate to the next process. Generally, the processing speed of the next process is lower than the maximum conveying speed of the roller conveyor. Therefore, a speed change interval needs to be determined in the final roller conveyor. When the head of the workpiece to be cut reaches the vicinity of the speed change interval, the speed V of the next process should be changed. Next Or stop. After comprehensive consideration, shift position P will be changed. change Set 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, thus leaving a buffer zone for the speed change of the object to be cut.

[0233] The next process mainly involves two signals affecting the roller conveyor: one is the Allow signal, which allows the roller conveyor to move forward. Next Only when this signal is 1 is the roller conveyor allowed to transport steel plates to the next process; another signal indicates that the steel plate is entering the next process, which is determined by the photoelectric switch at the entrance of the next process, denoted as Switch. Next When the signal is 1, it indicates that the workpiece to be cut is being conveyed to the next process. When the signal falls (the moment it changes from 1 to 0), it indicates that the tail of the workpiece has passed through the photoelectric switch at the entrance of the next process, and the conveying of one workpiece to be cut is complete.

[0234] When the head of the workpiece enters the final roller conveyor, the speed setting value of the final roller conveyor needs to be determined based on the two signals mentioned above, which can be divided into three cases:

[0235] 1) If the head of the workpiece to be cut has not yet reached the speed change position, and the steel plate is entering the next process, the signal switch will be activated. Next If the value is 0 (indicating there is no more material to be cut), then the final roller conveyor will operate at its highest speed V. Max run;

[0236] 2) When the head of the workpiece to be cut enters the speed change zone, if the steel plate is entering the next process, the signal switch will be activated. Next =0, and the allowable roller advance signal for the next process is Allow. Next =1 (indicating there are no more items to be cut and the material can be moved to the next process), then the speed V of the last roller conveyor for the next process is... Next Run; if Switch Next =0 and Allow Next =0 (indicating there are no more steel plates ahead but transport to the next process is not allowed), then set the speed of the final roller conveyor to 0.0, and wait for Allow. Next After changing to 1, the speed of the final roller conveyor is set to V. Next ;

[0237] 3) When the head of the object being cut enters the speed shift zone, if Switch Next =1, then the speed of the last section of the roller conveyor is set to 0.0;

[0238] Monitor for plate jamming; if a plate jams, the entire line will stop. Specifically:

[0239] At the moment when the signal for the workpiece to be cut changes from 0 to 1 as it is about to enter the next process (Switch) Next When the signal rises, the timer is started. The timer is reset when the signal changes from 1 to 0 as the workpiece is about to enter the next process (Switch). Next When the signal shows a falling edge, the timer's timing T is obtained. Next .

[0240] Calculate the theoretical transmission time T Trans :T Trans =L Plate / V next In the formula L Plate V represents the length of the object to be cut. Next The speed for the next process.

[0241] If T Next >T Trans +T1, where T1 is a preset time interval, which can be 8-12 seconds; in this embodiment, it is 10 seconds. An immediate full-line stop signal is triggered, and all roller conveyors stop instantly, awaiting operator intervention.

[0242] All the automatic control functions of the laser cutting unit mentioned above are programmed and implemented in PLC controller 1.

[0243] The automatic control method and system for a laser cutting machine provided in this invention first performs cutting positioning of the steel plate. A high-precision length grating is used to measure the transmission length of the steel plate. Compensation is performed on the calculated length at the moment the grating measurement value first becomes valid, which can significantly reduce the final positioning error. Then, a high-precision X-axis servo motor is used to compensate for the positioning error, completing the precise cutting positioning of the steel plate. The Y-axis servo motor is controlled to be positioned near the edge of the operating side of the steel plate. The cutting gas and laser are turned on in advance, and the machine moves at a constant speed to the outside of the transmission side edge of the steel plate, and then the cutting gas and laser are turned off after a delay to ensure that the steel plate is completely cut. After cutting, the Y-axis servo motor returns to the zero position at a varying speed, and automatic correction is performed at the zero-position limit switch. During cutting of the steel plate, the position difference is obtained by comparing the sensing distance with the set cutting height. The PLC calculates the speed and acceleration / deceleration of the Z-axis servo motor during the intermediate cutting process based on the position difference. Finally, a method for calculating the speed and acceleration / deceleration of the Z-axis servo motor when the laser head enters and exits the edge of the steel plate is provided, thereby maintaining a stable cutting height during cutting. After cutting, the steel plate is transported to the next process using conveyor rollers. The steel plate on each section of the roller conveyor is tracked, and the head and tail positions of the steel plate and the head and tail positioning signals of the segmented rollers are calculated in real time. A safety distance is set when the steel plate is conveyed on the intermediate roller conveyor, and the speed of the segmented roller conveyor is set based on the positioning signals 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, the speed of the final roller conveyor is set according to the signal from the next process, and the system monitors whether the steel plate jams while being conveyed to the next process. If jamming occurs, the entire line stops. This automatically completes the steel plate cutting process. This method achieves high-precision steel plate cutting positioning, precise positioning of four servo motors, solves the problem of cumulative error in the Y-axis servo motor, solves the problem of cutting height control during the cutting process, balances production efficiency and safety in the roller conveyor process, and achieves a smooth transition to the next process. Therefore, it realizes full automation and intelligence of the entire laser cutting process, reduces the labor intensity of workers, and improves production efficiency.

[0244] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An automatic control method for a laser cutting machine unit, characterized in that, The laser cutting unit includes: a transmission mechanism; a cutting machine frame mounted on the transmission mechanism along the width direction of the workpiece to be cut; a servo motor assembly for driving the movement of the cutting machine frame; and a length grating extending downstream of the cutting machine frame to the transmission endpoint of the transmission mechanism. The transmission mechanism includes drive rollers arranged sequentially along the transmission direction. The transmission mechanism has a cutting start position and a cutting position. The cutting start position is equipped with a start photoelectric switch and a first drive roller. The first drive roller is equipped with a drive roller encoder. Downstream of the first drive roller are a second drive roller and a third drive roller, and the cutting position is located between the second and third drive rollers. The machine frame is set above the cutting position. The two ends of the cutting machine frame are driven to move along the transmission direction by the first X-axis servo motor and the second X-axis servo motor, respectively. The first X-axis servo motor is equipped with an X-axis absolute encoder. The laser head is equipped on the cutting machine frame. The laser head moves along the width direction of the workpiece to be cut by the Y-axis servo motor. The Y-axis servo motor is equipped with a Y-axis absolute encoder. The laser head moves along the height direction of the workpiece to be cut by the Z-axis servo motor. The Z-axis servo motor is equipped with a Z-axis absolute encoder. The laser head is equipped with a laser head nozzle. The laser head nozzle is equipped with a distance sensor for determining the distance between the laser head nozzle and the workpiece to be cut. This method includes the following parts: P1. Precisely position the object to be cut: P101. Starting from the moment the head of the workpiece to be cut reaches the starting photoelectric switch, the calculated distance between the head of the workpiece and the cutting position is calculated based on the value of the transmission roller encoder; specifically: When the head of the object to be cut reaches the starting photoelectric switch, the length traveled by the object to be cut at each sampling moment is first calculated based on the value of the transmission roller encoder. The distance between the starting photoelectric switch and the cutting position is measured and denoted as . Starting from the start of the calculation of the transmission length of the object to be cut, accumulate the length elapsed at each sampling time. The total length traveled by the head of the object to be cut from the starting photoelectric switch is obtained and denoted as . The calculated distance between the head of the object to be cut and the cutting position is then... for ; P102. After the head of the workpiece to be cut enters the measurement area of ​​the length grating, the first valid measurement value of the length grating is used to compensate for the calculated distance between the head of the workpiece to be cut and the cutting position; the speed of the transmission roller is controlled according to the compensated calculated distance between the head of the workpiece to be cut and the cutting position; specifically: P102.1 Distance Compensation: Let the distance from the cutting position to the starting point of the length grating be . ,Will As the starting value for length grating measurement, the length grating measures the distance between the head of the object to be cut and the cutting position. After the object to be cut enters the measurement range of the length grating, if the measured value of the length grating is greater than a certain sampling time, the measurement will be performed. Then the measurement value at this moment is determined to be valid; Let time m be the time when the first valid sampling time for the grating measurement value occurs after the head of the object to be cut enters the grating measurement area; the grating measurement value at time m... The calculated distance between the head of the object to be cut and the cutting position. The error between them is recorded as a compensation value. : The calculated length of the object to be cut after compensation is set as follows: ,but: P102.2 Calculate the deceleration distance based on the maximum speed and deceleration of the drive roller: In the formula, This represents the maximum linear velocity of the drive roller. The deceleration of the drive roller, This is the distance the drive roller needs to travel to reduce its speed from maximum to zero. P102.3 Setting the speed of the drive roller: Let the cutting length of the object to be cut be... Then the distance that still needs to be transmitted is: Based on the remaining transmission distance, set the transmission speed to: In the formula, From The deceleration time is calculated from the start of each moment; when the remaining transmission distance is greater than the deceleration distance, the drive roller runs at maximum speed; when the remaining transmission distance is less than or equal to the deceleration distance, the drive roller decelerates. Decelerate to zero; P103. When the calculated distance between the head of the object to be cut and the cutting position reaches the specified length, the transmission stops, and a short preset time is allowed to wait for the length grating measurement value to stabilize. The positioning error of the object to be cut is calculated based on the length grating measurement value, and the X-axis servo motor is used to compensate for the positioning error, thereby adjusting the laser head to reach the accurate cutting position; specifically: P103.1 Calculate the positioning error: After the drive rollers decelerate to zero, wait a short time for the length grating measurement value to stabilize, read the current grating measurement value, calculate the positioning error of the workpiece to be cut, and use the grating measurement value. Calculate the positioning error of the object to be cut : In the formula The cutting length of the object to be cut; P103.2 Calculate the position of the laser head in the transmission direction of the workpiece to be cut: Taking the direction of the object to be cut as positive, the position when the laser head moves along the X-axis to the cutting position is: The position of the laser head in the transmission direction of the workpiece to be cut for: Controlling the servo motor assembly causes the laser head to move to... To achieve precise positioning; P2, Cutting: P201. Record the X-axis absolute encoder reading when in the cutting position, set the laser head position limit in the X-axis direction, and control the first and second X-axis servo motors to complete the cutting positioning. P202. Control the Y-axis servo motor to move the laser head to the cutting start point located on the edge of the object to be cut, turn on the laser and cutting gas, and the laser head moves along the Y-axis at a specified cutting speed to cut the object at a uniform speed. When the laser head moves to the cutting end point located on the other side of the object to be cut, the cutting is completed and the laser and cutting gas are turned off. P203. After the cutting is completed, the laser head returns to the cutting starting point along the Y-axis at a speed that changes from fast to slow. The cutting starting point is equipped with a zero-point limit switch. When the zero-point limit switch shows a rising edge signal, the laser head performs automatic zero-point correction in the Y-axis direction. P3. Calibration of the proximity sensor: P301. Adjust the laser head focal length to zero and check the laser head status signal. Set a calibration characteristic curve according to the cutting height range. The calibration characteristic curve consists of several feature points within the measurement range. When setting the calibration characteristic curve, set denser feature points within the cutting height range of the laser cutting machine and sparser feature points outside the cutting height range. Dense and sparse are relative concepts. P302. Control the Y-axis servo motor to move the laser head from its initial position to the top of the workpiece to be cut, and then control the Z-axis servo motor to descend until the laser head nozzle contacts the workpiece; control the Z-axis servo motor to move the laser head sequentially to each feature point on the calibration feature curve for calibration. P303. After calibration, control the Y and Z axis servo motors to return to the initial position and filter the distance sensor measurement values. P304. If a fault occurs during the calibration process, resolve the fault and restart the calibration. P4, Speed ​​Control: P401. Based on the installed photoelectric switches, the transmission mechanism is segmented along the transmission direction of the workpiece to be cut. Each segment is separated by two adjacent photoelectric switches. Within each segment, the positions of the head and tail of the workpiece to be cut are calculated, and head and tail positioning signals are generated respectively. The last segment is the final segment, and the other segments are intermediate segments. Specifically, the segmentation of the workpiece transmission rollers is performed as follows: Photoelectric switches are installed at certain intervals along the conveyor belt of the object to be cut, and an identification signal is emitted when an object to be cut passes through the position of the photoelectric switch. The transmission rollers between two adjacent photoelectric switches are grouped together, thereby dividing the entire conveyor roller track for the object to be cut into several segments. The transmission speed of the transmission rollers in each segment of the roller track changes together. Taking the starting position of the photoelectric switch on the conveyor roller of the object to be cut as the starting point, the position values ​​of all subsequent photoelectric switches relative to the starting point are measured as known values; The real-time position of the transmitted workpiece head is calculated as follows, and a head occupancy signal is generated: Let the position of the photoelectric switch at the starting position of a certain roller conveyor segment X be... The position of the photoelectric switch at the end of section X of the roller conveyor is as follows: When the head of the object to be cut reaches , The photoelectric switch at the location sends an identification signal, indicating that the head of the workpiece to be cut is positioned within section X of the roller conveyor. Set to 1; when the head of the object to be cut reaches , The photoelectric switch at the location sends an identification signal, indicating that the head of the workpiece to be cut is positioned within roller section X. Reset to 0; Occupation signal in the head Within a time interval of 1, based on the transmission speed of roller segment X, the distance the object to be cut is transmitted in roller segment X is accumulated once at each sampling moment to obtain the real-time position of the head of the object to be cut. The method for acquiring the real-time position of the tail of the object to be cut and the tail occupancy signal is the same as that for acquiring the real-time position of the head of the object to be cut and the head occupancy signal. P402. Set the safety distance between the objects to be cut. When conveying the objects to be cut on the intermediate roller conveyor, set the speed of each roller conveyor segment based on the head and tail positioning signals and the actual distance between the objects to be cut; specifically: Mark the roller conveyor segments along the direction of the material to be cut; 1) If there is a head-end occupancy signal on roller section X, while the tail-end occupancy signals on roller sections X+1 and X+2 are both 0, then roller section X will operate at its highest speed. run; 2) If there is a head-end occupancy signal on roller section X, a tail-end occupancy signal on roller section X+1 is 0, and a tail-end occupancy signal on roller section X+2 is 1, then calculate the distance between the two pieces of material to be cut using the following formula. : This refers to the tail end of the steel plate located on roller conveyor segment X+2. This refers to the head position of the workpiece to be cut, located on roller conveyor segment X. like Then the roller conveyor segment X operates at its highest speed. run; To maintain a safe distance; like And if the transmission speed of roller conveyor segment X+2 is 0.0, then the speed of roller conveyor segment X is set to 0.0; like Furthermore, the transmission speed of roller conveyor segment X+2 is a preset low speed. Then the speed of roller section X is set as ; 3) If there is a head occupancy signal on roller section X, and a tail occupancy signal on roller section X+1 is 1, then set the speed of roller section X to 0.

0. P403. Set a speed change range in the final section of the roller conveyor. When the head of the workpiece to be cut reaches the speed change range, the final section of the roller conveyor adjusts its speed according to the allowable roller conveyor advance signal of the next process and the signal that the workpiece to be cut is entering the next process. It also monitors whether the workpiece to be cut is stuck. If the workpiece to be cut is stuck, the entire line stops.

2. The automatic control method for a laser cutting unit according to claim 1, characterized in that, The P201 mentioned above is specifically: The positional relationship between the cutting position and the transmission roller used for transporting the workpiece to be cut is determined. The laser head is moved along the X-axis to the cutting position by the X-axis servo motor. The position value from the X-axis absolute encoder is then recorded as the cutting position value, denoted as [value missing]. ; Based on the distance between the drive rollers and the roller diameter, the range that the laser head can move back and forth along the X-axis at the cutting position is calculated, and a preset margin is left to obtain the X-axis position limit value; if the calculated cutting position setting value exceeds the X-axis position limit value, an alarm is triggered and the cutting step is stopped. A distance sensor is installed at the exit of the cutting machine to collect the distance from the head of the workpiece to the cutting position. Based on the length of the conveyed material collected by the distance sensor, the position setting value of the cutting position is calculated and denoted as [value missing]. Preset a small range of values ​​for the X-axis. As for the scope of arrival, record For the actual position of the cutting position, when When the time indicates that the position is reached, the X-axis servo motor stops moving; if The proportional controller is then used to calculate the setpoint for the X-axis servo motor's movement speed and apply a limit, as shown in the following formula: In the formula, The set values ​​for the moving speed of the X-axis servo motors on both sides. The limiting element representing the X-axis velocity. This is the proportional coefficient of the X-axis proportional controller.

3. The automatic control method for a laser cutting unit according to claim 1, characterized in that, In P202, controlling the Y-axis servo motor causes the laser head to move to the cutting starting point on the edge of the object to be cut, specifically: As the laser head moves along the Y-axis to the edge of the object to be cut, the set position value of the cutting start point is based on the edge position of the object to be cut calculated according to the width data, minus twice the maximum width error. Preset a small range of Y-axis values As the positioning range, when the difference between the actual position of the laser head on the Y-axis and the set position of the cutting starting point is outside the positioning range, the speed setting value for the first positioning on the Y-axis is calculated using the following formula: In the formula, The limiting element represents the Y-axis velocity. The scaling factor for the Y-axis. This represents the actual position of the laser head on the Y-axis. This is the set position value of the cutting start point when the laser head is first positioned.

4. The automatic control method for a laser cutting unit according to claim 1, characterized in that, In the aforementioned P403, the speed regulation specifically refers to: 1) The head of the workpiece to be cut has not yet reached the speed change position, and the steel plate is entering the next process signal. If the value is 0, then the final roller conveyor will operate at its highest speed. run; 2) When the head of the workpiece to be cut enters the speed change zone, if the steel plate is entering the next process signal... And the signal for the next process to allow the roller conveyor to advance. The speed of the next process on the last roller conveyor Run; if and Then set the speed of the final roller conveyor to 0.0 and wait. After changing to 1, the speed of the final roller conveyor is set to... ; 3) When the head of the workpiece enters the speed change range, if Then the speed of the final roller conveyor is set to 0.0; Monitor for plate jamming; if a plate jams, the entire line will stop. Specifically: A timer is started when the signal for the workpiece to be cut changes from 0 to 1 as it enters the next process. The timer is reset when the signal changes from 1 to 0, and the timer's duration is recorded. ; Calculate the theoretical transmission time : In the formula The length of the object to be cut. For the speed of the next process; like , At a preset time interval, a full-line stop signal is immediately triggered, and all roller conveyors stop instantly, awaiting operator intervention to resolve the malfunction.

5. An automatic control system for a laser cutting machine unit, characterized in that: This system includes a control unit and a frequency converter. The control unit is used to execute the automatic control method of the laser cutting machine unit according to any one of claims 1 to 4, and sends the speed set value of each roller conveyor segment to the frequency converter, which then sends it to the drive roller of each roller conveyor segment.

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