Robot transverse GTAW steel pipe butt joint welding wire, welding gun and electric arc posture control method

Abstract

The invention relates to the field of transverse GTAW steel pipe butt joint welding wire, welding gun and electric arc attitude control, in particular to a transverse GTAW steel pipe butt joint welding wire, welding gun and electric arc attitude control method based on structured light vision, attitude sensing and passive vision. The invention provides a method for controlling postures of a robot in butt joint with welding wires, welding guns and electric arcs for transverse GTAW steel pipes, aiming at the adverse effects of welding wire, welding gun and electric arc postures deviation on welding seam forming in butt joint welding of the transverse GTAW steel pipes. Recognizing the posture of the steel pipe by using a structured light visual sensing steel pipe posture recognition method; the wire filling posture is controlled through a robot GTAW steel pipe butt joint wire filling posture closed-loop control method; the posture of the welding gun is controlled through a robot GTAW steel pipe butt joint welding gun posture closed-loop control method; the electric arc heat is controlled through the electric arc heat control method based on passive vision.

Description

Technical Field

[0001] The invention relates to the field of transverse GTAW steel pipe butt welding wire, welding gun and arc posture control, and is a transverse GTAW steel pipe butt welding wire, welding gun and arc posture control method based on structured light vision, posture sensing and passive vision. Background Art

[0002] GTAW (gas shielded arc welding) is widely used in aerospace, marine equipment, nuclear power construction and other fields. In particular, the rapid development of arc additive technology in recent years has put forward higher requirements for the automation and intelligence of wire-filled GTAW. In the transverse GTAW steel pipe butt welding, the welding wire, welding gun and arc posture have a crucial influence on the weld formation. The present invention discloses a robot transverse GTAW steel pipe butt welding wire, welding gun and arc posture control method, which controls the welding wire, welding gun and arc posture during the welding process, thereby improving the stability of the welding process and the quality of the weld. Summary of the invention

[0003] The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is used to control the welding wire, welding gun, and arc posture in the robot GTAW steel pipe butt welding to obtain better welding quality, and is characterized in that: the robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is realized by using the robot GTAW steel pipe transverse butt welding wire, welding gun, and arc posture control system; the robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control system is composed of a steel pipe posture recognition system based on structured light vision sensing, a robot GTAW steel pipe butt welding wire posture control system, a robot GTAW steel pipe butt welding gun posture control system, and an arc heat control system; based on structured light vision sensing The steel pipe posture recognition method is implemented by using a steel pipe posture recognition system based on structured light vision sensing; the steel pipe posture recognition method based on structured light vision sensing is used to identify the posture of the steel pipe; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method is implemented by using a robot GTAW steel pipe butt welding wire filling posture control system; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method is used to control the wire filling posture; the robot GTAW steel pipe butt welding gun posture closed-loop control method is implemented by using a robot GTAW steel pipe butt welding gun posture control system; the robot GTAW steel pipe butt welding gun posture closed-loop control method is used to control the welding gun posture; the arc heat control method based on passive vision is used to control the arc heat. The schematic diagram of the robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control system is shown in Figure 1 shown.

[0004] A robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is characterized in that: the steel pipe posture recognition system based on structured light visual sensing is composed of a line laser, a left-eye camera, a right-eye camera, and a steel pipe image processing system; the line laser projects grating stripes to the surface of the steel pipe; the left-eye camera and the right-eye camera respectively collect laser stripes reflected by the workpiece; the line laser, the left-eye camera, and the right-eye camera are on the same horizontal line and fixed to the back plate; the steel pipe image processing system processes the images transmitted by the left-eye camera through the communication bus; the steel pipe posture recognition method based on structured light visual sensing obtains the angle α between the steel pipe and the X-axis of the world coordinate system through the steel pipe image processing system, The angle β with the Y axis and the angle γ with the Z axis; the world coordinate system takes the center of the bottom surface of the rotating worktable as the origin, the Y axis is parallel to the back plate, the X axis is perpendicular to the Y axis, and the X and Y axes are on the bottom surface plane of the rotating worktable, and the Z axis is vertically upward and perpendicular to the X and Y axes; the steel pipe image processing system obtains the internal and external parameters of the left eye camera and the right eye camera through calibration; the internal parameters are the focal length and principal point coordinates of the camera; the external parameters are the position and posture of the camera relative to the world coordinate system, and the phase shift method is used to obtain the absolute phase, and binocular matching is performed based on the phase to compare the position difference of the same feature points in the left and right eye camera images to calculate the parallax, and reconstruct the three-dimensional point cloud to obtain the three-dimensional spatial information of the steel pipe. The flow chart of the steel pipe posture recognition method based on structured light visual sensing is as follows: Figure 3 As shown in the figure, the world coordinate system diagram is as follows Figure 5 As shown, the angles α, β and γ between the workpiece and XYZ are shown in the figure. Figure 6 shown.

[0005] A robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is characterized in that: the robot transverse GTAW steel pipe butt welding wire filling posture control system is composed of a wire filling posture control mechanism, a wire feeding tube, and a wire filling control system; the wire filling posture control mechanism is composed of a wire filling six-axis posture sensor, a mechanical arm, and a transmission guide rail; the wire filling posture control system drives the mechanical arm and the transmission guide rail to move to a preset wire filling position; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method obtains the posture of the wire feeding tube through the wire filling posture six-axis sensor; the wire filling posture six-axis sensor is fixed at the front end of the wire feeding tube and is synchronous with the wire feeding tube Step movement; the six-axis sensor for wire filling posture integrates a three-axis gyroscope and a three-axis accelerometer, and transmits the wire feeding tube posture signal to the wire filling control system through the communication bus; the wire feeding tube posture is within the preset threshold range and does not need to be adjusted. If the wire feeding tube posture is outside the preset threshold range, the wire filling control system drives the mechanical arm and the transmission guide rail to return the wire feeding tube to the preset range; the preset range welding wire has an angle α with the X-axis, an angle (β-90°) with the Y-axis, and an angle (γ+70°) to (γ+80°) with the Z-axis; the angles α, β and γ are the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β with the Y-axis, and the angle γ with the Z-axis. The schematic diagram of the relative positions of the welding gun, welding wire and workpiece is shown in the figure. Figure 4 shown.

[0006] A robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is characterized in that: the robot GTAW steel pipe butt welding gun posture control system is composed of a welding gun, a welding gun rocker, a four-way moving track, a welding gun six-axis posture sensor and a welding gun posture control system; the welding gun rocker adjusts the angle ∈ between the welding gun and the back plate; the four-way moving track adjusts the welding gun to move freely along the X and Y axis directions of the world coordinate system; the welding gun posture control system drives the welding gun rocker and the four-way moving track to move to a preset welding position; the robot GTAW steel pipe butt welding gun posture closed-loop control method obtains the posture of the welding gun through the welding gun posture six-axis sensor; the welding gun posture six-axis sensor is fixed at the front end of the welding gun and is synchronized with the welding gun Movement; the welding gun posture six-axis sensor integrates a three-axis gyroscope and a three-axis accelerometer, and can transmit the welding gun posture signal to the welding gun posture control system through the communication bus; the welding gun posture does not need to be adjusted when it is within the preset threshold range. When the welding gun posture is outside the preset threshold range, the welding gun posture control system drives the welding gun rocker and the four-way moving track to return the welding gun to the preset range; the preset range of the welding gun and the X-axis angle is (α-50°) ~ (α-60°), the Y-axis angle is (β-30°) ~ (β-40°), and the Z-axis angle is (γ+100°) ~ (γ+120°); the angles α, β and γ are the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β with the Y-axis, and the angle γ with the Z-axis. The schematic diagram of the relative position of the welding gun, welding wire and workpiece is shown in Figure 4 shown.

[0007] A robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is characterized in that: the arc heat control system is composed of a magnetic field generating device, a passive camera, and an arc image processing system; the magnetic field generating device generates a magnetic field parallel to the welding direction to control the heat distribution of the arc at the weld groove; the passive camera can collect images of the molten pool; the magnetic field generating device and the passive camera move synchronously with the welding gun; the arc image processing system processes the image transmitted by the passive camera through the communication bus; the steel pipe workpiece is fixed to the rotating worktable through a rotating joint and rotates during the welding process; the arc heat control method based on passive vision is realized through the arc heat control system; the arc heat control method based on passive vision detects the melting condition of the molten pool through passive vision, and controls the concentration of arc heat by adjusting the size of the magnetic field. The area is designed to prevent excessive dripping of the base material; the detection of the melting condition of the molten pool determines whether the metal is dripping by detecting the brightness; the passive camera transmits the image to the arc image processing system through the communication bus; the arc image processing system grayscales the image and divides the image of the molten pool into two parts along the welding direction and calculates the brightness mean M of the lower part. When the brightness mean M is greater than the preset brightness mean N, the magnetic field size of the magnetic field generating device is increased; when the brightness mean M is less than or equal to the preset brightness mean N, it remains unchanged; the preset brightness mean N is the brightness value of the lower half of the image when the base material melts too much and drips; the magnetic field generating device controls the deflection of the arc by changing the size of the magnetic field and the magnetic field generating device is fixed at the front end of the welding gun and keeps consistent with the movement of the welding gun; the passive camera is consistent with the welding gun posture and can fully capture the molten pool image. The flow chart of passive visual detection of molten pool melting condition is as follows: Figure 2 shown.

[0008] Advantageous Effects of the Invention

[0009] The present invention relates to the field of transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control, and is a transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method based on structured light vision, posture sensing, and passive vision. In view of the adverse effects of welding wire, welding gun, and arc posture deviation on weld formation in transverse GTAW steel pipe butt welding, a robot transverse GTAW steel pipe butt welding welding wire, welding gun, and arc posture control method is proposed. A steel pipe posture recognition method using structured light vision sensing is used to identify the posture of the steel pipe; a robot GTAW steel pipe butt welding wire posture closed-loop control method is used to control the wire posture; a robot GTAW steel pipe butt welding gun posture closed-loop control method is used to control the welding gun posture; and an arc heat control method based on passive vision is used to control the arc heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1This is a schematic diagram of the robot's transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control system.

[0011] In the figure, 1 is a steel pipe workpiece, 2 is a weld, 3 is a rotary joint, 4 is a rotating base workbench, 5 is a right-eye camera, 6 is a passive camera, 7 is a magnetic field generating device, 8 is a left-eye camera, 9 is a welding gun, 10 is a welding gun rocker, 11 is a wire feeding tube, 12 is a line laser projector, 13 is a four-way moving track, 14 is a control bus, 15 is a communication bus, 16 is a transmission guide rail, 17 is a robotic arm, 18 is a six-axis sensor for wire filling posture, and 19 is a six-axis sensor for welding gun posture.

[0012] The image processing systems in the figure are the steel pipe image processing system and the arc image processing system.

[0013] The motor control system in the figure is the wire filling posture control system and the welding gun posture control system.

[0014] Figure 2 This is a flow chart for passive visual detection of molten pool melting conditions.

[0015] Figure 3 This is a flow chart of the steel pipe posture recognition method based on structured light visual sensing.

[0016] Figure 4 This is a schematic diagram of the relative positions of the welding gun, welding wire and workpiece.

[0017] Figure 5 Schematic diagram of the world coordinate system.

[0018] Figure 6 Schematic diagram of the angles α, β and γ between the workpiece and XYZ. DETAILED DESCRIPTION

[0019] In order to better express the technical solution and beneficial effects of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and implementation examples. The implementation method of the present invention is not limited thereto.

[0020] Step 1: Steel pipe posture recognition.

[0021] In transverse GTAW steel pipe butt welding, the steel pipe posture needs to be accurately identified. If the steel pipe posture is identified incorrectly, it will lead to errors in the control of the welding wire, welding gun and arc posture. In response to this problem, the present invention discloses a steel pipe posture recognition method based on structured light visual sensing. Before welding begins, a line laser projects grating stripes onto the steel pipe surface, and the left and right eye cameras respectively collect the laser stripes reflected by the workpiece. The steel pipe image processing system processes the images transmitted by the left and right eye cameras through the communication bus to obtain the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β between the steel pipe and the Y-axis, and the angle γ between the steel pipe and the Z-axis.

[0022] Step 2: Wire posture control.

[0023] In the horizontal GTAW steel pipe butt welding, the welding wire posture needs to be controlled in real time. If the welding wire posture is out of position, the welding process will be unstable and the weld forming quality will be reduced. In view of this problem, the present invention discloses a closed-loop control method for the filling wire posture of the robot GTAW steel pipe butt welding. Before welding starts, the six-axis filling wire posture sensor obtains the posture of the wire feeding tube and transmits the wire feeding tube posture signal to the filling wire control system. The filling wire control system drives the mechanical arm and the transmission guide rail to return the wire feeding tube to the preset range.

[0024] Step 3: Welding gun posture control.

[0025] In the transverse GTAW steel pipe butt welding, the welding gun posture needs to be controlled in real time. If the welding gun posture is out of position, the welding process will be unstable and the weld forming quality will be reduced. In view of this problem, the present invention discloses a closed-loop control method for the posture of a robot GTAW steel pipe butt welding gun. Before welding begins, the welding gun posture six-axis sensor obtains the posture of the welding gun and transmits the welding gun posture signal to the welding gun posture control system. The welding gun posture control system drives the welding gun rocker and the four-way moving track to return the welding gun to the preset range.

[0026] Step 4: Arc posture control.

[0027] In the transverse GTAW steel pipe butt welding, the arc posture needs to be controlled in real time. If the arc posture is misplaced, the base material will be melted too much and drip, forming a weld nodule on the back of the weld. In view of this problem, the present invention discloses a closed-loop control method for the posture of a robot GTAW steel pipe butt welding gun. After the welding starts, a passive camera can collect an image of the molten pool and transmit the image to an arc image processing system. The arc image processing system grayscales the image and divides the image of the molten pool into upper and lower parts along the welding direction and calculates the brightness mean M of the lower part. When the brightness mean M is greater than the preset brightness mean M, the magnetic field size of the magnetic field generating device is increased. When the brightness mean M is less than or equal to the preset brightness mean M, it remains unchanged. The magnetic field generating device controls the deflection of the arc by changing the size of the magnetic field.

Claims

1. A robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is used to control the welding wire, welding gun, and arc posture in the robot GTAW steel pipe butt welding to obtain better welding quality, and is characterized by: The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method is realized by using the robot GTAW steel pipe transverse butt welding wire, welding gun, and arc posture control system; the robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control system is composed of a steel pipe posture recognition system based on structured light vision sensing, a robot GTAW steel pipe butt wire filling posture control system, a robot GTAW steel pipe butt welding gun posture control system, and an arc heat control system; the steel pipe posture recognition method based on structured light vision sensing is realized by using the steel pipe posture recognition system based on structured light vision sensing; The steel pipe posture recognition method based on optical vision sensing is used to identify the posture of the steel pipe; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method is realized by using the robot GTAW steel pipe butt welding wire filling posture control system; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method is used to control the wire filling posture; the robot GTAW steel pipe butt welding gun posture closed-loop control method is realized by using the robot GTAW steel pipe butt welding gun posture control system; the robot GTAW steel pipe butt welding gun posture closed-loop control method is used to control the welding gun posture; the arc heat control method based on passive vision is used to control the arc heat.

2. The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method according to claim 1 is characterized by: The steel pipe posture recognition system based on structured light vision sensing is composed of a line laser, a left-eye camera, a right-eye camera and a steel pipe image processing system; the line laser projects grating stripes onto the surface of the steel pipe; the left-eye and right-eye cameras respectively collect laser stripes reflected by the workpiece; the line laser, the left-eye camera and the right-eye camera are on the same horizontal line and fixed to the back plate; the steel pipe image processing system processes the images transmitted by the left-eye and right-eye cameras through the communication bus; the steel pipe posture recognition method based on structured light vision sensing obtains the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β between the steel pipe and the Y-axis, and the angle γ between the steel pipe and the Z-axis through the steel pipe image processing system; The world coordinate system takes the center of the bottom surface of the rotating worktable as its origin, the Y axis is parallel to the back plate, the X axis is perpendicular to the Y axis, and the X and Y axes are on the plane of the bottom surface of the rotating worktable, and the Z axis is vertically upward and perpendicular to the X and Y axes; the steel pipe image processing system obtains the internal and external parameters of the left-eye camera and the right-eye camera through calibration; the internal parameters are the focal length and the principal point coordinates of the camera; the external parameters are the position and posture of the camera relative to the world coordinate system, and the phase shift method is used to obtain the absolute phase, and binocular matching is performed based on the phase to compare the position difference of the same feature points in the left and right eye camera images to calculate the parallax, and the three-dimensional point cloud is reconstructed to obtain the three-dimensional spatial information of the steel pipe.

3. The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method according to claim 1 is characterized in that: The robot transverse GTAW steel pipe butt welding wire filling posture control system is composed of a wire filling posture control mechanism, a wire feeding tube and a wire filling control system; the wire filling posture control mechanism is composed of a wire filling six-axis posture sensor, a mechanical arm and a transmission guide rail; the wire filling posture control system drives the mechanical arm and the transmission guide rail to move to a preset wire filling position; the robot GTAW steel pipe butt welding wire filling posture closed-loop control method obtains the posture of the wire feeding tube through the wire filling posture six-axis sensor; the wire filling posture six-axis sensor is fixed at the front end of the wire feeding tube and moves synchronously with the wire feeding tube; the wire filling posture six-axis sensor is internally The three-axis gyroscope and the three-axis accelerometer are integrated, and the wire feeding tube attitude signal is transmitted to the wire filling control system through the communication bus; when the wire feeding tube attitude is within the preset threshold range, no adjustment is required; when the wire feeding tube attitude is outside the preset threshold range, the wire filling control system drives the mechanical arm and the transmission guide rail to return the wire feeding tube to the preset range; the preset range includes an angle α between the welding wire and the X-axis, an angle (β-90°) with the Y-axis, and an angle (γ+70°) to (γ+80°) with the Z-axis; the angles α, β and γ are the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β with the Y-axis, and the angle γ with the Z-axis.

4. The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method according to claim 1 is characterized in that: The robot GTAW steel pipe butt welding gun posture control system is composed of a welding gun, a welding gun rocker, a four-way moving track, a welding gun six-axis posture sensor and a welding gun posture control system; the welding gun rocker adjusts the angle ∈ between the welding gun and the back plate; the four-way moving track adjusts the welding gun to move freely along the X and Y axis directions of the world coordinate system; the welding gun posture control system drives the welding gun rocker and the four-way moving track to move to a preset welding position; the robot GTAW steel pipe butt welding gun posture closed-loop control method obtains the posture of the welding gun through the welding gun posture six-axis sensor; The welding gun posture six-axis sensor is fixed at the front end of the welding gun and moves synchronously with the welding gun; the welding gun posture six-axis sensor integrates a three-axis gyroscope and a three-axis accelerometer, and can transmit the welding gun posture signal to the welding gun posture control system through the communication bus; when the welding gun posture is within the preset threshold range, no adjustment is required. When the welding gun posture is outside the preset threshold range, the welding gun posture control system drives the welding gun rocker and the four-way moving track to return the welding gun to the preset range; the preset range of the welding gun and the X-axis angle is (α-50°) to (α-60°), the Y-axis angle is (β-30°) to (β-40°), and the Z-axis angle is (γ+100°) to (γ+120°); the angles α, β and γ are the angle α between the steel pipe and the X-axis of the world coordinate system, the angle β with the Y-axis, and the angle γ with the Z-axis.

5. The robot transverse GTAW steel pipe butt welding wire, welding gun, and arc posture control method according to claim 1 is characterized in that: The arc heat control system is composed of a magnetic field generating device, a passive camera and an arc image processing system; the magnetic field generating device generates a magnetic field parallel to the welding direction to control the heat distribution of the arc at the weld groove; the passive camera can collect images of the molten pool; the magnetic field generating device and the passive camera move synchronously with the welding gun; the arc image processing system processes the image transmitted by the passive camera through the communication bus; the steel pipe workpiece is fixed to the rotating worktable through a rotating joint and rotates during the welding process; the arc heat control method based on passive vision is realized by the arc heat control system ... The control method detects the melting condition of the molten pool through passive vision, and controls the concentrated area of ​​arc heat by adjusting the size of the magnetic field to prevent the base material from dripping too much; the detection of the melting condition of the molten pool determines whether the metal drips by detecting the brightness; the passive camera transmits the image to the arc image processing system through the communication bus; the arc image processing system grayscales the image and divides the image of the molten pool into upper and lower parts along the welding direction and calculates the brightness mean M of the lower part, and increases the magnetic field size of the magnetic field generating device when the brightness mean M is greater than the preset brightness mean N, and remains unchanged when the brightness mean M is less than or equal to the preset brightness mean N; The preset brightness mean value N is the brightness value of the lower half of the image when the base material melts too much and produces the critical point of dripping; The magnetic field generating device controls the deflection of the arc by changing the size of the magnetic field and is fixed at the front end of the welding gun to keep consistent with the movement of the welding gun; the passive camera is consistent with the posture of the welding gun and can completely capture the molten pool image.

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