Welding workstation and welding process based on machine vision

Abstract

The invention discloses a welding workstation and a welding process based on machine vision, and belongs to the technical field of welding. According to the technical scheme, the welding workstation comprises a material table, a feeding robot and a welding workbench, and further comprises a visual fine positioning device; the welding workbench comprises a reference table top, and a lateral positioning mechanism is arranged on the reference table top. And a moving visual device is arranged at the moving end of the feeding robot. According to the scheme, the mobile vision device is arranged on the feeding robot, the positioning precision during material taking is improved through the mobile vision device, position information is accurately collected through the vision fine positioning device in the workpiece conveying process, the machining program or the feeding position is updated, and higher-precision machining is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a welding workstation and a welding process based on machine vision. Background Art

[0002] Welding technology is currently the most commonly used industrial production technology, with a very wide range of applications. It is a common technology in industrial production. In industrial production, although the performance of welding equipment has been greatly improved, the welding environment is still very harsh, which has certain harm to welders. At the same time, with the development of industry, precision welding has become increasingly stringent, and the technical requirements for workers in welding operations have also become higher. Under the influence of the working environment and operating skills, it is difficult for workers to maintain a high level of production for a long time. Therefore, the emergence of automated welding workstations has greatly replaced manual labor, has extremely high precision and stability, and can continue welding processing for a long time.

[0003] The automatic welding workstation is mainly composed of welding robots, welding equipment (such as welding power supply, welding gun, etc.), control systems and other auxiliary equipment (such as workpiece fixtures, conveying equipment, etc.). The computer system performs intelligent sensing of the welding environment, weld tracking and welding dynamic process, and performs real-time tracking and control of various complex spatial curve welds based on the sensing information. In the current automatic welding workstation, the system controls the welding gun to run according to the planned trajectory through preset programs and welding parameters, and performs real-time intelligent control of the welding dynamic process. Before welding is implemented, a computer software system for its welding path and welding parameters should be equipped. The software plans and designs the continuous trajectory of the weld space, the collision-free path of the welding movement and the welding gun posture, and optimizes the welding parameters according to the welding process.

[0004] Under the premise that the welding trajectory has been optimized and unified, improving the positioning accuracy of the workpiece in the workstation has become an important consideration for further improving welding accuracy. Summary of the invention

[0005] The present invention is aimed at the current automated welding workstation, and in order to further improve the welding accuracy, provides a welding workstation which can reposition the workpiece through a machine vision system and has higher welding accuracy.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a welding workstation, including a material table, a loading robot and a welding workbench, and also including a visual precision positioning device; the welding workbench includes a reference table, and a lateral positioning mechanism is provided on the reference table; the moving end of the loading robot is provided with a mobile visual device. In this solution, a mobile visual device is provided on the loading robot, and the positioning accuracy when picking up materials is improved by the mobile visual device, and the position information is accurately collected by the visual precision positioning device during the transportation of the workpiece, and the processing program or the loading position is updated to achieve higher-precision processing.

[0007] Preferably, the lateral positioning mechanism comprises a column, one side of which is a positioning surface and is perpendicular to the reference table surface, a clamping cylinder is provided at the upper end of the column, a pressure plate is provided at the telescopic end of the clamping cylinder, and the pressure plate is parallel to the positioning surface.

[0008] Preferably, two lateral positioning mechanisms are provided, and the positioning surfaces of the two positioning mechanisms are arranged coplanarly, so as to realize double-point positioning of the workpiece and improve positioning stability.

[0009] Preferably, it also includes a welding robot, and along the first direction, the material table, the visual precision positioning device, the welding workbench and the welding robot are arranged in sequence, and the feeding robot is arranged on one side of the visual precision positioning device to optimize the equipment layout and improve the turnover processing efficiency of the workpiece.

[0010] On the other hand, the present invention also provides a welding process based on machine vision, comprising the following steps: S1. Write the processing program; S2. Set the reference position of the motherboard and realize accurate loading of the motherboard through the visual precision positioning device and the mobile visual device; S3. Set the reference position of the material and realize the disorderly loading of the material through the visual precision positioning device and the mobile visual device; S4. Weld each material in turn to complete the welding.

[0011] Preferably, in step S2: Set the coordinate compensation amount (δ1,0,0) of the motherboard and the motherboard reference position L0 (X0,Y0,Z0); The loading robot places the motherboard at the initial position on the reference table of the welding workbench, and the lateral positioning mechanism on the reference table fixes the position of the motherboard in the Y direction in the horizontal plane; The mobile vision device of the loading robot extracts the motherboard position data L2 (X1, Y1, Z1); The difference between L0 and L2 is used as the adjustment value to adjust the position of the motherboard and the coordinate value of the motherboard in the industrial control system to make it coincide with the robot world coordinate.

[0012] Preferably, it is assumed that: δ0 is the fixed value of welding process δ2=|(Y1-Y0) / Y0| δ3=|(Z1-Z0) / Z0| When δ2 and δ3 are greater than δ0, it indicates that there is an error in the position of the motherboard when the welding platform 6 is clamped 9, and manual intervention is required to re-clamp the motherboard and re-execute step S1; When δ2 and δ3 are less than δ0, the difference δ1=Z1-Z0 is transmitted to the 7 master control system, and the 7 master control system uses δ1 as the adjustment value.

[0013] Preferably, in step S3: The mobile vision device on the loading robot collects the location of each material: According to the welding sequence, the loading robot grabs the materials in turn, and the visual precision positioning device accurately identifies the grabbed materials and calculates the difference between the materials and the origin of the visual precision positioning device in turn; Adjust the variables of the machining program according to the difference; The loading robot guides the material, loads the material and precisely positions the material relative to the motherboard based on the updated processing program.

[0014] Preferably, the material positions are: L101(x 101 ,y 101 ,z 101 ,θ 101 ) L100(x 102 ,y 102 ,z 102 ,θ 102 ) ...... L1n(x 1n ,y 1n ,z 1n ,θ 1n ) ...... After the loading robot grabs the material, it moves to the specified position L above the 4-vision precision positioning system. 21 (x 21 ,y 21 ,z 21 ), and make preliminary adjustments to material C during the move n The angle error of The visual precision positioning system accurately identifies the material coordinates again and extracts the material coordinate value L 2n (x 2n ,y 2n ,z 2n ,θ 2n), the material's current coordinate value and the origin position coordinate of the visual precision positioning system L 20 (x 20 ,y 20 ,z 20 , θ 20 ) is: δ 21 = x 2n -x 20 δ 22 = y 2n -y 20 δ 23 = z 2n -z 20 δ 24 =θ 2n -θ 20 .

[0015] Preferably, when the visual precision positioning system performs the next recognition, the obtained difference data overwrites the previous difference data.

[0016] It can be seen from the above technical solutions that the advantages of the present invention are that the workstation for intelligent welding with disordered material loading and offline programming can be realized by compensating the coordinate error of the material. The efficiency and application scope of programming can be improved by offline programming. The accuracy and application scope of welding can be improved by compensating the coordinate error. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0018] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the material platform in Example 1 of the present invention.

[0020] Description of main reference numerals 1. Material table, 2. Loading robot, 3. Mobile vision device, 4. Visual precision positioning device, 5. End effector, 6. Welding workbench, 601. Reference table, 602. Lateral positioning mechanism, 7. Welding robot, 8. Industrial control system. DETAILED DESCRIPTION

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0022] Embodiment 1 like Figure 1 As shown, a welding workstation includes a material table 1, a feeding robot 2, a welding worktable 6, a welding robot 7 and a visual precision positioning device 4. Along a first direction, the material table 1, the visual precision positioning device 4, the welding worktable 6 and the welding robot 7 are arranged in sequence. Along a second direction, the feeding robot 2 is arranged on one side of the visual precision positioning device 4. The first direction and the second direction are perpendicular to each other in a horizontal plane. Figure 2 As shown, the welding workbench 6 includes a reference table top 601, on which a lateral positioning mechanism 602 is provided, the lateral positioning mechanism includes a column, one side of the column is a positioning surface and is perpendicular to the reference table top, a clamping cylinder is provided at the upper end of the column, a pressure plate is provided at the telescopic end of the clamping cylinder, and the pressure plate is parallel to the positioning surface, and two lateral positioning mechanisms are provided, and the positioning surfaces of the two positioning mechanisms are coplanar.

[0023] The feeding robot 2 can adopt a multi-joint mechanical arm structure, and its moving end is provided with an end effector 5, which is a conventional structure of the feeding robot. On this basis, the present scheme is also provided with a mobile visual device 3 at the moving end, and the mobile visual device 3 includes a visual camera and a structure such as a supplementary light matched therewith, and the visual precision positioning device also adopts a visual camera. At the same time, the material coordinate recognition accuracy of the two cameras in the mobile visual device 3 and the visual precision positioning device 4 is inversely proportional to the performance and field of view of the camera, that is, for cameras with the same performance, a large field of view means low accuracy. Therefore, in order to improve the positioning accuracy of the material, the visual precision positioning device 4 adopts a fixed positioning and a small field of view setting to improve the recognition accuracy of the material. The mobile visual device 3 needs to take into account the motherboard positioning and material recognition functions, so the local feature recognition method is adopted for the motherboard position positioning. The motherboard adopts a fixed positioning method in the Y direction and the Z direction, and the coordinate value of the feature point recognition by the mobile visual device can be used to judge the positioning accuracy of the X direction through the values ​​in the Y direction and the Z direction, thereby improving the positioning accuracy in the X direction.

[0024] Embodiment 2 Based on the workstation provided in the first embodiment, this embodiment further provides a welding process based on machine vision: Step 1: Write an offline welding program according to the intelligent welding workstation, motherboard, and materials. In the offline program, two sets of compensation variables are set. By adjusting the values ​​of the compensation variables, the disordered loading of materials and the precise positioning of the motherboard can be achieved.

[0025] The two sets of compensating variables are Motherboard coordinate compensation (δ1,0,0) Material coordinate compensation (δ 21 ,δ 22 ,δ 23 ,δ 24 ) Step 2: Mark the soldering sequence according to the characteristics of the soldering positions on the motherboard Position number A1, A2, A3, ..., A n ,…….

[0026] Mark according to the welding sequence of materials Material number C1, C2, C3, ..., C n ,…….

[0027] Step 3: The lateral clamping mechanism 602 clamps the motherboard under the control of the welding station control system 603.

[0028] Step 4: The loading robot 2 carries the mobile vision device 3 and moves to the positioning position L1 above the welding workbench 6. The mobile vision device 3 extracts the position features of the motherboard and extracts the position data L2 (X1, Y1, Z1) of the motherboard features.

[0029] Comparing the characteristic position data L2 (X1, Y1, Z1) with the offline data L0 (X0, Y0, Z0), since the height and lateral positioning position of the welding workbench 6 are fixed values, the errors of Y1 and Y0, Z1 and Z0 should be within the specified values.

[0030] δ2=|(Y1-Y0) / Y0| δ3=|(Z1-Z0) / Z0| When δ2 and δ3 are greater than δ0 (fixed value of welding process), it means that the position of the motherboard clamped by the welding workbench 6 is wrong, and manual intervention is required to re-clamp and repeat steps 3 and 4. Step 5, when δ2 and δ3 are less than δ0 (fixed value of welding process), the difference δ1=Z1-Z0 is transmitted to the master control system 8, and the master control system uses δ1 as the adjustment value to adjust the coordinate value of the motherboard in the robot industrial control system and the robot industrial control system to make it coincide with the robot world coordinate.

[0031] Step 6: The loading robot 2 carries the mobile visual device 3 and moves to the positioning position L above the material table 1. 11, take photos in sequence along the direction of material table 1, identify the materials, and mark each material C n Location L101(x 101 ,y 101 ,z 101 ,θ 101 ) L100(x 102 ,y 102 ,z 102 ,θ 102 ) ...... L1n(x 1n ,y 1n ,z 1n ,θ 1n ) ...... Step 7: According to the welding sequence, the loading robot 2 carries the end effector 5 to grab the material C in sequence. n , and move to the specified position L above the visual precision positioning device 4 21 (x 21 ,y 21 ,z 21 ), and make preliminary adjustments to material C during the move n The angular error (θ 1n ).

[0032] Step 8: Visual precision positioning device 4 positions material C n The coordinates are accurately identified again and material C is extracted n Coordinate value L 2n (x 2n ,y 2n ,z 2n ,θ 2n ), and calculate material C in turn n The current coordinate value and the origin position coordinate L of the visual precision positioning device 4 20 (x 20 ,y 20 ,z 20 , θ 20 ) δ 21 = x 2n -x 20 , δ 22 = y 2n -y 20 δ 23 = z 2n -z 20 δ 24 =θ2n -θ 20 The values ​​are temporarily stored in the industrial control system of the visual precision positioning device, and the data is transmitted to the master control system, which writes the data into the variables in the offline programming program.

[0033] At the same time, the above values ​​are overwritten during the next position recognition.

[0034] Step 9: The loading robot 2 carries the material C grabbed by the end effector 5 n , material guidance, material loading and precise material positioning are carried out under the updated offline program.

[0035] Step 10, 7 the welding robot performs welding or riveting work under the updated offline program.

[0036] Step 11, the welding robot completes welding and returns to its original position.

[0037] Step 12, 4 actuators release the material and return to the original position of the feeding robot 2.

[0038] Step 13, proceed to the next cycle and grab material C n+1 Repeat steps 6-12 until the material loading process is completed.

[0039] Step 14, the lateral positioning mechanism of the welding workbench 6 is released to complete the welding work.

[0040] It can be seen from the above embodiments that the beneficial effect of the present invention is that a workstation for intelligent welding with disordered material loading and offline programming can be realized by compensating for coordinate errors of materials. Offline programming can improve the efficiency and scope of programming. Compensating for coordinate errors can improve the precision and scope of welding.

[0041] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A welding workstation, comprising a material table (1), a loading robot (2) and a welding worktable (6), characterized in that: It also includes a visual precision positioning device (4); the welding workbench (6) includes a reference table (601), and a lateral positioning mechanism (602) is provided on the reference table (601); and the moving end of the feeding robot (2) is provided with a mobile visual device.

2. The welding workstation according to claim 1, characterized in that: The lateral positioning mechanism comprises a column, one side of which is a positioning surface and is perpendicular to the reference table surface, a clamping cylinder is arranged at the upper end of the column, a pressing plate is arranged at the telescopic end of the clamping cylinder, and the pressing plate is parallel to the positioning surface.

3. The welding workstation according to claim 2, characterized in that: There are two lateral positioning mechanisms, and the positioning surfaces of the two positioning mechanisms are coplanar.

4. The welding workstation according to claim 1, characterized in that: It also comprises a welding robot (7), wherein the material table (1), the visual precision positioning device (4), the welding workbench (6) and the welding robot (7) are arranged in sequence along a first direction, and the loading robot (2) is arranged on one side of the visual precision positioning device (4).

5. A welding process based on machine vision, characterized in that: The following steps are involved: S1. Write the processing program; S2. Setting the reference position of the motherboard, and realizing accurate loading of the motherboard through the visual precision positioning device (4) and the mobile visual device; S3. Set the reference position of the material, and realize the disorderly loading of the material through the visual precision positioning device (4) and the mobile visual device; S4. Weld each material in turn to complete the welding.

6. The machine vision-based welding process according to claim 5, characterized in that: In step S2: Set the coordinate compensation amount (δ1,0,0) of the motherboard and the motherboard reference position L0 (X0,Y0,Z0); The loading robot (2) places the motherboard at an initial position on the reference table of the welding workbench, and the lateral positioning mechanism on the reference table fixes the position of the motherboard in the Y direction in the horizontal plane; The mobile vision device of the loading robot (2) extracts the motherboard position data L2 (X1, Y1, Z1); The difference between L0 and L2 is used as the adjustment value to adjust the position of the motherboard and the coordinate value of the motherboard in the industrial control system to make it coincide with the robot world coordinate.

7. The machine vision-based welding process according to claim 6, characterized in that: set up: δ0 is the fixed value of welding process δ2=|(Y1-Y0) / Y0| δ3=|(Z1-Z0) / Z0| When δ2 and δ3 are greater than δ0, it indicates that there is an error in the position of the motherboard when the welding platform 6 is clamped 9, and manual intervention is required to re-clamp the motherboard and re-execute step S1; When δ2 and δ3 are less than δ0, the difference δ1=Z1-Z0 is transmitted to the 7 master control system, and the 7 master control system uses δ1 as the adjustment value.

8. The machine vision-based welding process according to claim 5, characterized in that: In step S3: The mobile vision device on the loading robot collects the location of each material: According to the welding sequence, the loading robot grabs the materials in turn, and the visual precision positioning device accurately identifies the grabbed materials and calculates the difference between the materials and the origin of the visual precision positioning device in turn; Adjust the variables of the machining program according to the difference; The loading robot guides the material, loads the material and precisely positions the material relative to the motherboard based on the updated processing program.

9. The machine vision-based welding process according to claim 8, characterized in that: The locations of the materials are: L101(x 101 ,y 101 ,z 101 ,θ 101 ) L100(x 102 ,y 102 ,z 102 ,i 102 ) ...... L1n(x 1n ,y 1n ,z 1n ,θ 1n ) ...... After the loading robot grabs the material, it moves to the specified position L above the 4-vision precision positioning system. 21 (x 21 ,y 21 ,z 21 ), and make preliminary adjustments to material C during the move n The angular error (θ 1n ); The visual precision positioning system accurately identifies the material coordinates again and extracts the material coordinate value L 2n (x 2n ,y 2n ,z 2n ,θ 2n ), the material's current coordinate value and the origin position coordinate of the visual precision positioning system L 20 (x 20 ,y 20 ,z 20 , θ 20 ) is: δ 21 = x 2n - x 20 δ 22 = and 2n - and 20 δ 23 = from 2n - With 20 d 24 =θ 2n -θ 20 。 10. The machine vision-based welding process according to claim 8, characterized in that: When the visual precision positioning system performs the next recognition, the obtained difference data overwrites the previous difference data.

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