A bending robot automatic control system

Abstract

This invention relates to an automatic control system for a bending robot, belonging to the field of bending robot technology. It includes a bending machine, a bending robot for gripping sheet metal parts, and a CNC module. The CNC module acquires real-time data and sends commands. The bending machine includes a bending frame, a linear encoder, a balancing mechanism, a back gauge, a slider, a hydraulic cylinder, an upper template, and a lower template. The bending frame includes an upper beam, a lower beam, and two side plates. The hydraulic cylinder is mounted on the upper beam, and the slider is connected to the hydraulic cylinder. The upper template is located at the lower end of the slider, and the lower template is mounted on the lower beam. The balancing mechanism is connected to the lower beam. The linear encoder is mounted on the slider and connected to the balancing mechanism. The back gauge is located between the two side plates. The lower beam is constructed from three sheet metal pieces and is equipped with a compensation cylinder. The middle sheet metal slides up and down under the action of the compensation cylinder. This invention achieves real-time closed-loop control of the bending process, improving the bending accuracy of sheet metal parts through synchronous following, automatic edge finding, and deformation compensation operations.

Description

Technical Field

[0001] This invention relates to the field of bending robot technology, and in particular to an automatic control system for a bending robot. Background Technology

[0002] Sheet metal bending is a key forming process for most sheet metal parts, significantly impacting their appearance and dimensional accuracy. To improve bending efficiency and safety, bending robots are now used to replace manual bending. These robots use suction cups and other devices to hold the sheet metal in place at the robot's end effector. The robot then moves the corresponding bending point to the designated position on the bending machine. During bending, the robot's end effector follows the sheet metal, achieving bending through a following mechanism. With the development of smart factories, using automated robotic bending systems for high-quality bending production has become a new trend.

[0003] For example, the invention patent with application number CN201810395898.5 discloses a PLC-controlled bending device. However, due to factors such as bending deformation and the influence of the algorithm itself, the existing bending robot has low accuracy when bending sheet metal parts. Summary of the Invention

[0004] To address the problem of low bending accuracy in sheet metal parts, this invention provides an automatic control system for a bending robot.

[0005] The automatic control system for a bending robot provided by this invention adopts the following technical solution:

[0006] An automatic control system for a bending robot includes: a bending machine, a bending robot for gripping sheet metal parts, and a CNC module. The CNC module is used to acquire real-time data of the bending machine and the bending robot and send instructions. The bending machine includes a bending frame, a grating ruler, a balancing mechanism, a back gauge, a slider, a hydraulic cylinder, an upper template, and a lower template. The bending frame includes an upper beam, a lower beam, and two side plates. The hydraulic cylinder is mounted on the upper beam, and the slider is connected to the hydraulic cylinder. The upper template is mounted at the lower end of the slider and fits into the lower template. The lower template is mounted on the lower beam. The balancing mechanism is connected to the lower beam and mounted on both sides of the bending frame. The grating ruler is mounted on the slider and connected to the balancing mechanism. The back gauge is mounted between the two side plates. The lower beam is made of three sheet metal pieces spliced ​​together. A compensation cylinder is installed in the lower beam, and the middle sheet metal slides up and down under the action of the compensation cylinder.

[0007] Preferably, the balancing mechanism includes a fixed block, a spring, a slide groove, a horizontal bar, a pulley, and a C-shaped frame. The C-shaped frame is connected to the lower beam. The fixed block is mounted on the side plate of the bending machine and connected to the upper end of the horizontal bar via the spring. The slide groove is mounted on the upper end of the C-shaped frame and connected to the lower end of the horizontal bar via the pulley. The grating ruler includes a grating strip and a reading head. The grating strip is mounted on the slider, and the reading head slides along the grating strip and is connected to the horizontal bar. The balancing mechanism compensates for the measurement error of the grating ruler during the bending process.

[0008] Preferably, the bending robot obtains the position of the grating ruler and achieves synchronous following through the dynamic geometric relationship between the bending robot and the slider.

[0009] Preferably, synchronous following is achieved through the dynamic geometric relationship between the bending robot and the slider, including:

[0010] The distance the slider moves downwards is determined by the position of the grating ruler;

[0011] The angle between the sheet metal part and the horizontal direction during the bending process is calculated by the downward movement distance of the upper template;

[0012] The coordinates of the contact point between the bending robot and the sheet metal part are calculated based on the included angle, so that the bending robot can achieve synchronous following through coordinates.

[0013] Preferably, the angle between the sheet metal part and the horizontal direction during the bending process is calculated by the moving distance of the upper template, using the following formula:

[0014]

[0015] in, The radius of the fillet on the template of the bending machine. t is the radius of the lower template of the bending machine, w is the thickness of the sheet metal to be processed, h is the opening width of the lower template mold, and h is the pressing distance of the upper template of the bending machine after it contacts the sheet metal.

[0016] Preferably, the coordinates of the contact point between the bending robot and the sheet metal part are calculated based on the included angle, using the following formula:

[0017]

[0018] in, This refers to the displacement perpendicular to the contact point between the bending robot and the sheet metal part. This represents the horizontal displacement at the contact point between the bending robot and the sheet metal part. This refers to the angle between the sheet metal part and the horizontal plane during the bending process. This is the vertical distance between the contact point and the lower bending point of the sheet metal part. L is the horizontal distance between the contact point and the lower bending point of the sheet metal part, and L is the horizontal distance between the contact point and the lower bending point of the sheet metal part before bending.

[0019] Preferably, the back gauge includes a guide rail, multiple back gauge fingers, and multiple displacement sensors. The guide rail connects to the two side plates, the back gauge fingers are mounted on the guide rail and slide along the guide rail, and the displacement sensors are mounted on the back gauge fingers.

[0020] Preferably, the displacement sensor measures the distance between the sensor and the sheet metal part in real time, and analyzes the distance measured by the displacement sensor to determine whether the sheet metal part has reached the set bending position. If the values ​​measured by all displacement sensors are equal and are the set values, it is determined that the sheet metal part has reached the set bending position; otherwise, the CNC module feeds back to the bending robot for real-time adjustment to achieve automatic edge finding.

[0021] Preferably, the upper and lower templates are equipped with precision potentiometers to collect deformation data and obtain the hydraulic compensation value of the bending machine. The CNC module calculates and adjusts the pressure of the compensation cylinder in real time according to the hydraulic compensation value of the bending machine until the upper and lower beams are parallel.

[0022] Preferably, the relationship between the hydraulic compensation value of the bending machine and the pressure of the compensation cylinder is as follows:

[0023]

[0024] Where C is the hydraulic compensation value of the bending machine, n is the number of compensation cylinders, D is the diameter of the compensation cylinder, and P is the pressure of the compensation cylinder. To compensate for the cylinder spacing, The distance between the two side panels. To compensate for the distance between the hydraulic cylinder and the two side plates, E is the elastic modulus of the lower beam. Let be the moment of inertia of the lower beam.

[0025] In summary, the present invention has the following beneficial technical effects:

[0026] 1. The system uses data captured in real time during the bending process to direct the bending machine and bending robot to work together and achieve real-time closed-loop control of the bending process accuracy. Through synchronous following, automatic edge finding and deformation compensation, the bending accuracy of sheet metal parts is improved.

[0027] 2. Using bending robots to replace bending workers in sheet metal bending operations reduces the workload of bending workers, simplifies management, and eliminates safety hazards. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an automatic control system for a bending robot according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the bending machine structure shown in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the balancing mechanism structure shown in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the back gauge structure shown in an embodiment of the present invention;

[0032] Figure 5 This is a cross-sectional view of the lower beam of the bending machine shown in an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached drawings: 1. Bending machine; 2. Bending robot; 3. CNC module; 4. Grating ruler; 5. Balancing mechanism; 6. Back gauge; 7. Slider; 8. Hydraulic cylinder; 9. Upper template; 10. Lower template; 11. Upper beam; 12. Lower beam; 13. Side plate; 14. Compensating cylinder; 15. Fixing block; 16. Spring; 17. Slide groove; 18. Horizontal bar; 19. Pulley; 20. C-frame; 21. Grating bar; 22. Reading head; 23. Guide rail; 24. Back gauge finger; 25. Displacement sensor. Detailed Implementation

[0034] The following is in conjunction with the appendix Figure 1-5 The present invention will be described in further detail below.

[0035] This invention discloses an automatic control system for a bending robot, such as... Figure 1-2 As shown, the system includes: a bending machine 1, a bending robot 2 for gripping sheet metal parts, and a CNC module 3. The CNC module 3 is used to acquire real-time data of the bending machine 1 and the bending robot 2 and send instructions. The bending machine 1 includes a bending frame, a grating ruler 4, a balancing mechanism 5, a back gauge 6, a slider 7, a hydraulic cylinder 8, an upper template 9, and a lower template 10. The bending frame includes an upper beam 11, a lower beam 12, and two side plates 13. The hydraulic cylinder 8 is mounted on the upper beam 11, and the slider 7 is connected to the hydraulic cylinder 8. The upper template 9 is mounted at the lower end of the slider 7 and fits into the lower template 10. The lower template 10 is mounted on the lower beam 12. The balancing mechanism 5 is connected to the lower beam 12 and mounted on both sides of the bending frame. The grating ruler 4 is mounted on the slider 7 and connected to the balancing mechanism 5. The back gauge 6 is mounted between the two side plates 13. The lower beam 12 is made of three sheet metal pieces spliced ​​together. A compensation cylinder 14 is installed in the lower beam 12, and the middle sheet metal slides up and down under the action of the compensation cylinder 14.

[0036] The CNC module adopts a PC-based central control system, which can handle more complex algorithms compared to existing PLC host computers, enabling data monitoring and optimization. The CNC module stores core algorithms for robot synchronous following, automatic edge finding, and error compensation. During synchronous following, automatic edge finding, and error compensation operations, closed-loop control is implemented. The CNC module collects the required data in real time and adjusts the issued instructions based on feedback information.

[0037] In this embodiment, the bending robot 2 is a six-axis manipulator equipped with a seventh-axis guide rail drive system. The manipulator is mounted on the manipulator guide rail, which expands the working area of ​​the manipulator. It can handle larger workpieces or operate in a wider working area. The manipulator can translate and rotate on the manipulator guide rail as needed to adapt to different work requirements and achieve more precise positioning and control.

[0038] like Figure 3 As shown, the balancing mechanism 5 includes a fixed block 15, a spring 16, a slide groove 17, a horizontal bar 18, a pulley 19, and a C-shaped frame 20. The C-shaped frame 20 is connected to the lower beam 12. The fixed block 15 is set on the side plate 13 of the bending machine and is connected to the upper end of the horizontal bar 18 through the spring 16. The slide groove 17 is set on the upper end of the C-shaped frame 20 and is connected to the lower end of the horizontal bar 18 through the pulley 19. The grating ruler 4 includes a grating strip 21 and a reading head 22. The grating strip 21 is set on the slider 7. The reading head 22 slides along the grating strip 21 and is connected to the horizontal bar 18. The balancing mechanism 5 compensates for the measurement error of the grating ruler 4 during the bending process.

[0039] For all bending machines, the most unavoidable problem is the "opening" effect caused by the deformation of the side plates of the cantilever structure under the reaction force during the bending process. The grating strip 21 of the grating ruler 4 is mounted on the slider 7. If the reading head 22 is directly fixed to the two side plates 13, the "opening" deformation will cause measurement errors by the grating ruler 4. Therefore, a C-shaped bracket 20 is fixed on each side of the bottom of the lower beam 12 of the bending machine 1 to connect the grating ruler 4. Since the C-shaped bracket 20 is independent of the two side plates 13, it will not move with the side plates during the bending process. The plate 13 deforms and deforms; when deformation occurs, the fixed block 15 moves upward along the two side plates 13 with the deformation, and the spring 16 connected to the fixed block 15 pulls the end connected to the horizontal bar 18 upward. The horizontal bar 18 returns to the horizontal position under the action of the pulley 19. When the horizontal bar 18 returns to the horizontal position, the reading head 22 connected to the horizontal bar 18 slides on the grating bar 21 accordingly. The sliding distance of the reading head 22 is the displacement of the slider 7 during the deformation process, which compensates for the measurement error of the grating ruler 4.

[0040] The bending robot 2 acquires the position of the grating ruler 4 and achieves synchronous following through the dynamic geometric relationship between the bending robot 2 and the slider 7. This synchronous following through the dynamic geometric relationship between the bending robot 2 and the slider 7 includes:

[0041] The distance by which the slider 7 moves the upper template 9 downward is obtained by the position of the grating ruler 4. The downward movement of the upper template 9 is divided into two stages: the first stage is when the upper template 9 does not contact the sheet metal part, and the second stage is from when the upper template 9 contacts the sheet metal part until the sheet metal part is bent. Since the distance between the upper template 9 and the lower template 10 is fixed at the initial position, the downward movement distance of the upper template 9 in the two stages can be calculated according to the thickness of the sheet metal part. The first downward movement of the upper beam 11 is very fast. At the deceleration point, the CNC system controls it to change to enter a slow working state. The deceleration point is set according to actual needs and is usually set at a position of 6 mm above the bending point.

[0042] The angle between the sheet metal part and the horizontal direction during the bending process is calculated by the downward movement distance of the upper template. The formula is:

[0043]

[0044] in, The radius of the fillet on the template of the bending machine. t is the radius of the lower template of the bending machine, w is the thickness of the sheet metal to be processed, h is the opening width of the lower template mold, and h is the downward pressing distance after the upper template of the bending machine contacts the sheet metal.

[0045] The coordinates of the contact point between the bending robot and the sheet metal part are calculated based on the included angle, enabling the bending robot to achieve synchronous following through coordinates. Since there are often multiple contact points between the bending robot and the sheet metal part, the bending robot adjusts in conjunction with the coordinates of all contact points at each moment. The real-time coordinate calculation formula for each contact point is as follows:

[0046]

[0047] in, This refers to the displacement perpendicular to the contact point between the bending robot and the sheet metal part. This represents the horizontal displacement at the contact point between the bending robot and the sheet metal part. This refers to the angle between the sheet metal part and the horizontal plane during the bending process. This is the vertical distance between the contact point and the lower bending point of the sheet metal part. L is the horizontal distance between the contact point and the lower bending point of the sheet metal part, and L is the horizontal distance between the contact point and the lower bending point of the sheet metal part before bending.

[0048] By calculating the coordinates of the contact point in real time and following the movement of the contact point, the bending robot adjusts its position and posture in real time to maintain a stable connection between the bending robot and the sheet metal part. This avoids bending errors in the sheet metal part or damage to mechanical parts caused by the bending robot following the wrong direction, ensuring the stability and reliability of the bending operation, while achieving fast and accurate bending operations.

[0049] like Figure 4 As shown, the back gauge 6 includes a guide rail 12, multiple back gauge fingers 24, and multiple displacement sensors 25. The guide rail 12 is connected to the two side plates 13. The back gauge fingers 24 are mounted on the guide rail 12 and slide along the guide rail 12. The displacement sensors 25 are mounted on the back gauge fingers 24. The back gauge is mounted on the linear guide rail with the two side plates as the reference surface. It uses a precision gear and rack transmission method, which can ensure the parallelism of the left and right support surfaces of the back gauge beam without any adjustment. The back gauge fingers can be precisely adjusted in the front-back direction and the up-down direction by a wedge mechanism, which ensures that the back gauge can complete the positioning requirements of complex bending workpieces at the most flexible, precise and high speed.

[0050] The displacement sensor measures the distance between the sensor and the sheet metal part in real time. The distance measured by the displacement sensor is analyzed to determine whether the sheet metal part has reached the set bending position. If the values ​​measured by all displacement sensors are equal and are the set values, it is determined that the sheet metal part has reached the set bending position. Otherwise, the CNC module feeds back to the bending robot for real-time adjustment to achieve automatic edge finding.

[0051] Precision potentiometers are installed on the upper template 9 and the lower template 10 to collect real-time deformation data of the upper and lower beams and obtain the hydraulic compensation value of the bending machine. The CNC module 3 calculates and adjusts the pressure of the compensation cylinder in real time according to the hydraulic compensation value of the bending machine until the upper and lower beams are parallel.

[0052] like Figure 5 As shown, the lower template 10 is set at the upper center of the middle plate. When the compensation cylinder 14 is used for deflection compensation, since the plate in the middle of the lower beam 12 can slide up and down, the compensation cylinder 14 lifts the plate in the middle part when it is working, ensuring the best compensation effect when the compensation cylinder 14 is working. When the compensation cylinder 14 is not working, the lower beam 12 returns to its natural state.

[0053] The relationship between the hydraulic compensation value of the bending machine and the pressure of the compensation cylinder is as follows:

[0054]

[0055] Where C is the hydraulic compensation value of the bending machine, n is the number of compensation cylinders (n≥3), D is the diameter of the compensation cylinder, and P is the pressure of the compensation cylinder. To compensate for the cylinder spacing, The distance between the two side panels. To compensate for the distance between the hydraulic cylinder and the two side plates, E is the elastic modulus of the lower beam. Let be the moment of inertia of the lower beam.

[0056] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An automatic control system for a bending robot, characterized in that, include: A bending machine, a bending robot for gripping sheet metal parts, and a CNC module are disclosed. The CNC module is used to acquire real-time data from the bending machine and the bending robot and send instructions. The bending machine includes a bending frame, a linear encoder, a balancing mechanism, a back gauge, a slider, a hydraulic cylinder, an upper template, and a lower template. The bending frame includes an upper beam, a lower beam, and two side plates. The hydraulic cylinder is mounted on the upper beam, and the slider is connected to the hydraulic cylinder. The upper template is mounted at the lower end of the slider and fits into the lower template. The lower template is mounted on the lower beam. The balancing mechanism is connected to the lower beam and mounted on both sides of the bending frame. The linear encoder is mounted on the slider and connected to the balancing mechanism. The back gauge is mounted between the two side plates. The lower beam is made of three sheet metal pieces spliced ​​together. A compensation cylinder is installed in the lower beam, and the middle sheet metal slides up and down under the action of the compensation cylinder. Precision potentiometers are installed on the upper and lower templates to collect deformation data and obtain the hydraulic compensation value of the bending machine. The CNC module calculates and adjusts the pressure of the compensation cylinder in real time according to the hydraulic compensation value of the bending machine until the upper and lower beams are parallel. The relationship between the hydraulic compensation value of the bending machine and the pressure of the compensation cylinder is as follows: Where C is the hydraulic compensation value of the bending machine, n is the number of compensation cylinders, D is the diameter of the compensation cylinder, and P is the pressure of the compensation cylinder. To compensate for the cylinder spacing, This refers to the distance between the two side panels. To compensate for the distance between the hydraulic cylinder and the two side plates, E is the elastic modulus of the lower beam. Let be the moment of inertia of the lower beam.

2. The automatic control system for a bending robot according to claim 1, characterized in that, The balancing mechanism includes a fixed block, a spring, a slide groove, a horizontal bar, a pulley, and a C-shaped frame. The C-shaped frame is connected to the lower beam. The fixed block is set on the side plate of the bending machine and connected to the upper end of the horizontal bar via the spring. The slide groove is set on the upper end of the C-shaped frame and connected to the lower end of the horizontal bar via the pulley. The grating ruler includes a grating strip and a reading head. The grating strip is set on the slider, and the reading head slides along the grating strip and is connected to the horizontal bar. The balancing mechanism compensates for the measurement error of the grating ruler during the bending process.

3. The automatic control system for a bending robot according to claim 1, characterized in that, The bending robot obtains the position of the grating ruler and achieves synchronous following through the dynamic geometric relationship between the bending robot and the slider.

4. The automatic control system for a bending robot according to claim 3, characterized in that, Synchronous following is achieved through the dynamic geometric relationship between the bending robot and the slider, including: The distance the slider moves downwards is determined by the position of the grating ruler; The angle between the sheet metal part and the horizontal direction during the bending process is calculated by the downward movement distance of the upper template; The coordinates of the contact point between the bending robot and the sheet metal part are calculated based on the included angle, so that the bending robot can achieve synchronous following through coordinates.

5. The automatic control system for a bending robot according to claim 4, characterized in that, The angle between the sheet metal part and the horizontal direction during the bending process is calculated by the distance the upper template moves. The formula is: in, The radius of the fillet on the template of the bending machine. t is the radius of the lower template of the bending machine, w is the thickness of the sheet metal to be processed, h is the opening width of the lower template mold, and h is the pressing distance of the upper template of the bending machine after it contacts the sheet metal.

6. The automatic control system for a bending robot according to claim 5, characterized in that, The coordinates of the contact point between the bending robot and the sheet metal part are calculated based on the included angle, using the following formula: in, This refers to the displacement perpendicular to the contact point between the bending robot and the sheet metal part. This represents the horizontal displacement at the contact point between the bending robot and the sheet metal part. This refers to the angle between the sheet metal part and the horizontal plane during the bending process. This is the vertical distance between the contact point and the lower bending point of the sheet metal part. L is the horizontal distance between the contact point and the lower bending point of the sheet metal part, and L is the horizontal distance between the contact point and the lower bending point of the sheet metal part before bending.

7. The automatic control system for a bending robot according to claim 1, characterized in that, The back gauge includes a guide rail, multiple back gauge fingers, and multiple displacement sensors. The guide rail is connected to the two side plates. The back gauge fingers are mounted on the guide rail and slide along the guide rail. The displacement sensors are mounted on the back gauge fingers.

8. The automatic control system for a bending robot according to claim 7, characterized in that, The displacement sensor measures the distance between the sensor and the sheet metal part in real time. The distance measured by the displacement sensor is analyzed to determine whether the sheet metal part has reached the set bending position. If the values ​​measured by all displacement sensors are equal and are the set values, it is determined that the sheet metal part has reached the set bending position. Otherwise, the CNC module feeds back to the bending robot for real-time adjustment to achieve automatic edge finding.

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