High-efficiency GTAW welding method with alternating longitudinal oscillation of front and rear double wires

Abstract

The present invention relates to the field of twin-wire GTAW control and is a method for high-efficiency GTAW welding with alternating longitudinal oscillation of twin wires. In view of the high difficulty of twin-wire welding and the difficulty in controlling process parameters during twin-wire GTAW, a method for high-efficiency GTAW welding with alternating longitudinal oscillation of twin wires is proposed. The twin-wire alternating oscillation method is used to control the alternating oscillation of the twin wires; the twin-wire alternating oscillation welding wire position control method is used to control the oscillation amplitude of the front and rear wire feed sliders; and the twin-wire alternating oscillation welding wire frequency control method is used to control the oscillation frequency of the front and rear wire feed sliders.

Description

Technical Field

[0001] The invention relates to the field of filler wire GTAW double-wire control, and is a high-efficiency GTAW welding method of alternate longitudinal oscillation of front and rear double wires. 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 double-wire GTAW. In the double-wire GTAW process, double-wire welding is difficult and the process parameters are difficult to control. In response to the above difficulties, the present invention discloses a high-efficiency GTAW welding method with alternating longitudinal oscillations of front and rear double wires. The purpose of optimizing double-wire welding is achieved by controlling the alternating longitudinal oscillations of the front and rear double wires during the double-wire GTAW process. Summary of the Invention

[0003] The invention relates to a high-efficiency GTAW welding method for alternating longitudinal oscillation of front and rear double wires, which is used to control the alternating oscillation of front and rear double wires during the wire-filling GTAW process to obtain higher cladding efficiency and better welding quality. The method is characterized in that: the high-efficiency GTAW welding method for alternating longitudinal oscillation of front and rear double wires is realized by utilizing a high-efficiency GTAW welding system for alternating longitudinal oscillation of front and rear double wires; the high-efficiency GTAW welding system for alternating longitudinal oscillation of front and rear double wires is composed of a GTAW welding robot, a double wire oscillation control system, an arc signal acquisition system, an industrial computer, a control bus and a communication bus; the GTAW welding robot is composed of an X-guide rail, a Y-guide rail, a Z-guide rail, a work platform and a welding gun clamping device for controlling the welding gun for welding; the vertex of the workpiece is taken as The coordinate origin is used to establish a world coordinate system along the X-guide rail as the X-axis, along the Y-guide rail as the Y-axis, and along the Z-guide rail as the Z-axis; the dual-wire oscillation control system is used to control the amplitude and frequency of the dual-wire oscillation; the arc signal acquisition system is used to acquire the tungsten extreme arc signal, the front welding wire end arc signal and the rear welding wire end arc signal; the tungsten extreme arc signal is the arc voltage between the tungsten electrode and the workpiece; the front welding wire end arc signal is the arc voltage between the front welding wire and the workpiece; the rear welding wire end arc signal is the arc voltage between the rear welding wire and the workpiece; the industrial computer is used to control the movement of the GTAW welding robot, the front wire feed slider and the rear wire feed slider; the control bus and the communication bus are used to transmit signals. The front and rear dual-wire alternating oscillation high-efficiency GTAW welding system is shown in the figure below. Figure 1 shown.

[0004] The method is characterized in that: a double-wire oscillation control system is used to control the amplitude and frequency of the double-wire alternating oscillation; the double-wire oscillation control system is composed of a double-wire oscillation device, a front welding wire oscillation guide rail, a rear welding wire oscillation guide rail, a front wire feed slider, and a rear wire feed slider; the double-wire oscillation device is fixedly connected to the welding gun clamping device, the front welding wire oscillation guide rail, and the rear welding wire oscillation guide rail; the groove rail length of the front welding wire oscillation guide rail is h, and the center point of the bottom surface of the front welding wire oscillation guide rail is the origin, along the three-axis direction of the world coordinate system XYZ axis. Establish a front welding wire coordinate system for the XYZ axis; the groove rail length of the rear welding wire oscillation guide rail is h and the center point of the bottom surface of the rear welding wire oscillation guide rail is the origin, and the rear welding wire coordinate system is established along the three-axis direction of the world coordinate system XYZ axis for the XYZ axis; the front wire feeding slider can slide along the positive or negative direction of the Y axis of the front welding wire coordinate system in the groove rail of the front welding wire oscillation guide rail; the rear wire feeding slider can slide along the positive or negative direction of the Y axis of the rear welding wire coordinate system in the groove rail of the rear welding wire oscillation guide rail; the initial position of the front wire feeding slider is located at the bottom end of the groove rail in the front wire feeding guide rail, that is, the Y axis of the front welding wire coordinate system 前 =0 and the sliding range is from Y 前 =0 to Y 前 = h; the initial position of the rear wire feed slider is located at the bottom of the groove rail in the rear wire feed guide rail, that is, the rear welding wire coordinate system Y 后 =0 and the sliding range is from Y 后 =0 to Y 后 =h. The schematic diagram of the front welding wire coordinate system, the rear welding wire coordinate system and the world coordinate system is as follows Figure 2 shown.

[0005] The method is characterized in that: a double wire alternating longitudinal oscillation method is used to control the double wire alternating oscillation; the double wire alternating oscillation method controls the front and rear wire feed slider to repeat the double wire oscillation cycle to achieve the double wire alternating oscillation; the double wire oscillation cycle time T = t f +t b ;t f =t2+t m ;t b =t1+t n ;t f The dwell time of the front wire at the droplet transfer position driven by the front wire feed slider; t b is the time that the rear wire feed slider drives the rear wire to stay at the droplet transfer position; t1 is the time that the front wire feed slider drives the front wire to stay at the optimal melting position; t2 is the time that the rear wire feed slider drives the rear wire to stay at the optimal melting position; t m The time required for the rear wire feed slider to move the rear wire from the optimal melting position to the droplet transfer position and the front wire feed slider to move the front wire from the droplet transfer position to the optimal melting position; t nIt is the time required for the front wire feed slider to drive the front wire from the optimal melting position to the droplet transfer position, while the rear wire feed slider drives the rear wire from the droplet transfer position to the optimal melting position. The line graph of an oscillation cycle with time t as the horizontal axis and height h as the vertical axis is as follows: Figure 4 shown.

[0006] The invention relates to a high-efficiency GTAW welding method of alternating longitudinal oscillation of front and rear double wires, characterized in that: a double-wire alternating oscillation welding wire position control method is used to control the oscillation amplitude of the front wire feed slider and the oscillation amplitude of the rear wire feed slider; the double-wire alternating oscillation welding wire position control method controls the front welding wire or the rear welding wire to move upward to the optimal melting position during the front or rear droplet growth stage, and controls the front welding wire or the rear welding wire to move downward to the droplet transition position during the front or rear droplet transition stage so that it contacts the molten pool and completes the droplet transfer; the optimal front melting position is determined by calculating the tungsten extreme arc voltage U w The arc voltage U at the front wire end fh Difference U w -U fh Search, when ΔU fmin ≤U w -U fh ≤ΔU fmax When ΔU fmin With ΔU fmax The optimal rear end melting position is determined by calculating the tungsten extreme arc voltage U w The arc voltage U at the rear wire end bh Difference U w -U bh Search, when ΔU bmin ≤U w -U bh ≤ΔU bmax When ΔU bmin With ΔU bmax It is a preset threshold value based on the temperature distribution of the welding arc; the setting of the threshold value ensures that the welding wire is in the highest temperature area while avoiding being too close to the tungsten electrode to cause adhesion; the molten droplet transition position is obtained by detecting the arc signal at the front wire end or the arc signal at the rear wire end. When the arc voltage signal at the front wire end is 0v, the welding wire position is the front wire molten droplet transition position, and when the arc voltage signal at the rear wire end is 0v, the welding wire position is the rear wire molten droplet transition position. The double-wire alternating oscillation welding wire position control method controls the oscillation amplitude of the front wire feed slider and the oscillation amplitude of the rear wire feed slider. The flow chart is as follows Figure 5 The schematic diagram of high-efficiency GTAW welding with alternating oscillation of front and rear double wires is shown as follows. Figure 3 shown.

[0007] The invention discloses a high-efficiency GTAW welding method of alternating longitudinal oscillation of front and rear double wires, which is characterized by: utilizing a double-wire alternating oscillation welding wire frequency control method to control the oscillation frequency of the front wire feed slider and the oscillation frequency of the rear wire feed slider; utilizing a molten droplet growth time calculation method to calculate the front molten droplet growth time t1 and the rear molten droplet growth time t2 in the front or rear end molten droplet growth stage; utilizing a molten droplet transition detection method to detect whether the molten droplet transition stage is completed in the front or rear end molten droplet transition stage, thereby realizing the control of the double-wire alternating oscillation welding wire frequency; the molten droplet growth time calculation method is to pre-set the mass m1 of each molten droplet of the front welding wire and the mass m2 of each molten droplet of the rear welding wire; the molten droplet growth time t1 of the front welding wire is equal to m1 / (ρ1πr1v1); the molten droplet growth time t2 of the rear welding wire is equal to m2 / (ρ 2πr2v2); wherein ρ1 is the front wire density, ρ2 is the rear wire density, r1 is the front wire radius, r2 is the rear wire radius, v1 is the front wire filling speed, and v2 is the rear wire filling speed; the droplet transition detection method is realized by detecting the arc signal at the front wire end and the arc signal at the rear wire end, and after the droplet growth time of the current wire ends, the front wire is controlled to move downward to the droplet transition position, and when the arc signal at the current wire end is greater than 0v again, the front droplet transition stage ends, and the front wire is controlled to move upward to the optimal melting position; when the droplet growth time of the rear wire ends, the rear wire is controlled to move downward to the droplet transition position, and when the arc signal at the rear wire end is greater than 0v again, the rear droplet transition stage ends, and the rear wire is controlled to move upward to the optimal melting position.

[0008] Advantageous Effects of the Invention

[0009] The present invention relates to the field of twin-wire GTAW control and is a method for high-efficiency GTAW welding with alternating longitudinal oscillation of twin wires. In view of the high difficulty of twin-wire welding and the difficulty in controlling process parameters during twin-wire GTAW, a method for high-efficiency GTAW welding with alternating longitudinal oscillation of twin wires is proposed. The twin-wire alternating oscillation method is used to control the alternating oscillation of the twin wires; the twin-wire alternating oscillation welding wire position control method is used to control the oscillation amplitude of the front and rear wire feed sliders; and the twin-wire alternating oscillation welding wire frequency control method is used to control the oscillation frequency of the front and rear wire feed sliders. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram of the high-efficiency GTAW welding system with alternating oscillation of front and rear double wires.

[0011] In the figure, 1 is an industrial computer, 2 is a control bus, 3 is a communication bus, 4 is an arc signal acquisition system, 5 is an X-guide rail, 6 is a front welding wire oscillation guide rail, 7 is a welding gun, 8 is a Z-guide rail, 9 is a Y-guide rail, 10 is a rear wire feeding slider, 11 is a double-wire oscillation device, 12 is a rear welding wire oscillation guide rail, 13 is a front wire feeding slider, 14 is a workpiece, 15 is a working platform, 16 is a grounding wire, 17 is a welding gun clamping device, 18 is a front welding wire, and 19 is a rear welding wire.

[0012] Figure 2 Schematic diagram of the front welding wire coordinate system, the rear welding wire coordinate system and the world coordinate system.

[0013] Figure 3 Schematic diagram of high-efficiency GTAW welding with alternating oscillation of front and rear double wires.

[0014] Figure 4 It is a line graph of an oscillation cycle with time t as the horizontal axis and height h as the vertical axis.

[0015] Figure 5 The present invention is a flow chart of a method for controlling the oscillation amplitude of the front wire feed slider and the oscillation amplitude of the rear wire feed slider in a double-wire alternating oscillation welding wire position control method. DETAILED DESCRIPTION

[0016] In order to better illustrate the technical solutions 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.

[0017] Step 1: Alternate oscillation control of the front and rear double wires.

[0018] In the double-wire GTAW process, it is necessary to control the front wire feed slider and the rear wire feed slider to repeat the double-wire oscillation cycle. If the oscillation cycle is set improperly, it will lead to a decrease in cladding efficiency and an unstable welding process. To solve this problem, the present invention discloses a double-wire alternating oscillation method. Figure 4 Set the welding cycle, the front wire moves from the droplet transfer position to the optimal melting position when the rear wire reaches the droplet transfer position, and the rear wire moves from the droplet transfer position to the optimal melting position when the front wire reaches the droplet transfer position.

[0019] Step 2: Control the oscillation amplitude of the front wire feed slider and the rear wire feed slider.

[0020] In the double-wire GTAW process, it is necessary to control the oscillation amplitude of the front wire feed slider and the rear wire feed slider. If the longitudinal position of the wire is too high, the welding process will be unstable; if the longitudinal position of the wire is too low, the melting efficiency of the wire will decrease. In response to this problem, the present invention discloses a double-wire alternating oscillation wire position control method. After the welding starts, the arc signal acquisition system collects the arc signal and transmits it to the industrial control computer through the communication bus. The industrial control computer will calculate the tungsten terminal voltage U w , the difference in arc voltage at the front wire end U fh The difference between the arc voltage at the rear wire end and the arc voltage at the rear wire end is U bh , in the front or rear droplet growth stage, control the front wire or rear wire to move upward to the optimal melting position, when ΔU fmin ≤U w -U fh ≤ΔU fmax When ΔU bmin ≤U w -U bh ≤ΔU bmax When the front or rear end is in the droplet transition stage, the front or rear wire is controlled to move downward to the droplet transition position so that it contacts the molten pool and completes the droplet transition. When the arc voltage signal at the front wire end is 0v, the wire position is considered to be the front wire droplet transition position. When the arc voltage signal at the rear wire end is 0v, the wire position is considered to be the rear wire droplet transition position.

[0021] Step 3: Control the oscillation frequency of the front wire feed slider and the oscillation frequency of the rear wire feed slider.

[0022] In the double-wire GTAW process, it is necessary to control the oscillation frequency of the front wire feed slider and the oscillation frequency of the rear wire feed slider. To address this problem, the present invention discloses a double-wire alternating oscillation welding wire frequency control method. Before welding begins, the front droplet growth time t1 and the rear droplet growth time t2 are calculated. By presetting the mass m1 of each droplet of the front welding wire and the mass m2 of each droplet of the rear welding wire, the front welding wire droplet growth time t1 = m1 / (ρ1πr1v1) and the rear welding wire droplet growth time t2 = m2 / (ρ2πr2v2) are obtained. After the current welding wire droplet growth time ends, the front welding wire is controlled to move downward to the droplet transfer position. When the arc signal at the current welding wire end is greater than 0V again, the front welding wire is controlled to move upward to the optimal melting position. When the rear welding wire droplet growth time ends, the rear welding wire is controlled to move downward to the droplet transfer position. When the arc signal at the rear welding wire end is greater than 0V again, the rear welding wire is controlled to move upward to the optimal melting position.

Claims

1. The high-efficiency GTAW welding method with alternating longitudinal oscillation of two front and rear wires is used to control the alternating oscillation of two front and rear wires during the GTAW process with filler wire to achieve higher cladding efficiency and better welding quality. It is characterized by: The front and rear double-wire alternating longitudinal oscillation high-efficiency GTAW welding method is realized by using a front and rear double-wire alternating longitudinal oscillation high-efficiency GTAW welding system; the front and rear double-wire alternating longitudinal oscillation high-efficiency GTAW welding system is composed of a GTAW welding robot, a double-wire oscillation control system, an arc signal acquisition system, an industrial computer, a control bus, and a communication bus; the GTAW welding robot is composed of an X-guide rail, a Y-guide rail, a Z-guide rail, a work platform, and a welding gun clamping device for controlling the welding gun to perform welding; the workpiece vertex is taken as the coordinate origin and the direction along the X-guide rail is the X-axis, and the direction along the Y-guide rail is the Z-axis. The guiding direction is the Y-axis, and the guiding direction along the Z-guide rail is the Z-axis to establish a world coordinate system; the dual-wire oscillation control system is used to control the amplitude and frequency of the dual-wire oscillation; the arc signal acquisition system is used to acquire the tungsten extreme arc signal, the front welding wire end arc signal and the rear welding wire end arc signal; the tungsten extreme arc signal is the arc voltage between the tungsten electrode and the workpiece; the front welding wire end arc signal is the arc voltage between the front welding wire and the workpiece; the rear welding wire end arc signal is the arc voltage between the rear welding wire and the workpiece; the industrial computer is used to control the GTAW welding robot, the front wire feeding slider and the rear wire feeding slider The slider moves; the control bus and the communication bus are used to transmit signals; the double-wire oscillation control system is used to realize the control of the double-wire alternating oscillation amplitude and frequency; the double-wire oscillation control system is composed of a double-wire oscillation device, a front welding wire oscillation guide rail, a rear welding wire oscillation guide rail, a front wire feeding slider and a rear wire feeding slider, and is used to realize the control of the double-wire alternating oscillation amplitude and frequency; the double-wire oscillation device is fixedly connected to the welding gun clamping device, the front welding wire oscillation guide rail and the rear welding wire oscillation guide rail; the groove rail length of the front welding wire oscillation guide rail is h and the center point of the bottom surface of the front welding wire oscillation guide rail is the origin, along the world coordinate The three-axis direction of the XYZ axis is used to establish a front welding wire coordinate system; the length of the groove of the rear guide rail of the welding wire oscillation is h and the center point of the bottom surface of the rear welding wire oscillation guide rail is used as the origin, and the three-axis direction of the XYZ axis of the world coordinate system is used to establish a rear welding wire coordinate system; the front wire feeding slider can slide along the positive or negative direction of the Y axis of the front welding wire coordinate system in the groove of the front welding wire oscillation guide rail; the rear wire feeding slider can slide along the positive or negative direction of the Y axis of the rear welding wire coordinate system in the groove of the rear welding wire oscillation guide rail; the initial position of the front wire feeding slider is located at the bottom end of the groove in the front wire feeding guide rail, that is, the Y axis of the front welding wire coordinate system 前 =0 and the sliding range is from Y 前 =0 to Y 前 = h; the initial position of the rear wire feed slider is located at the bottom of the groove rail in the rear wire feed guide rail, that is, the rear welding wire coordinate system Y 后 =0 and the sliding range is from Y 后 =0 to Y 后 =h; The high-efficiency GTAW welding method of alternating longitudinal oscillation of the front and rear double wires utilizes a double-wire alternating oscillation method to control the alternating oscillation of the front and rear double wires, utilizes a double-wire alternating oscillation welding wire position control method to control the oscillation amplitude of the front wire feed slider and the oscillation amplitude of the rear wire feed slider, and utilizes a double-wire alternating oscillation welding wire frequency control method to control the oscillation frequency of the front wire feed slider and the oscillation frequency of the rear wire feed slider.

2. The high-efficiency GTAW welding method with alternating longitudinal oscillation of two front and rear wires according to claim 1, characterized in that: The double wire alternating oscillation method is used to control the alternating oscillation of the front and rear double wires; the double wire alternating oscillation method realizes the alternating oscillation of the front and rear double wires by controlling the front wire feed slider and the rear wire feed slider to repeat the double wire oscillation cycle movement; the double wire oscillation cycle time T=t f +t b ;t f =t2+t m ;t b =t1+t n ;t f The dwell time of the front wire at the droplet transfer position driven by the front wire feed slider; t b is the time that the rear wire feed slider drives the rear wire to stay at the droplet transfer position; t1 is the time that the front wire feed slider drives the front wire to stay at the optimal melting position; t2 is the time that the rear wire feed slider drives the rear wire to stay at the optimal melting position; t m The time required for the rear wire feed slider to move the rear wire from the optimal melting position to the droplet transfer position and the front wire feed slider to move the front wire from the droplet transfer position to the optimal melting position; t n It is the time required for the front wire feed slider to drive the front welding wire from the optimal melting position to the droplet transfer position, while the rear wire feed slider drives the rear welding wire from the droplet transfer position to the optimal melting position.

3. The high-efficiency GTAW welding method with alternating longitudinal oscillation of two front and rear wires according to claim 1, characterized in that: The double-wire alternating oscillation welding wire position control method is used to control the oscillation amplitude of the front wire feed slider and the oscillation amplitude of the rear wire feed slider; the double-wire alternating oscillation welding wire position control method controls the front welding wire or the rear welding wire to move upward to the optimal melting position during the front or rear end molten droplet growth stage, and controls the front welding wire or the rear welding wire to move downward to the molten droplet transition position during the front or rear end molten droplet transition stage so that it contacts the molten pool and completes the molten droplet transfer; the optimal front melting position is calculated by calculating the tungsten extreme arc voltage U w The arc voltage U at the front wire end fh Difference U w -U fh Search, when ΔU fmin ≤U w -U fh ≤ΔU fmax When ΔU fmin With ΔU fmax The optimal rear end melting position is determined by calculating the tungsten extreme arc voltage U w The arc voltage U at the rear wire end bh Difference U w -U bh Search, when ΔU bmin ≤U w -U bh ≤ΔU bmax When ΔU bmin With ΔU bmax It is a threshold value preset according to the temperature distribution of the welding arc; the setting of the threshold value ensures that the welding wire is in the highest temperature area while avoiding adhesion due to being too close to the tungsten electrode; the molten droplet transfer position is obtained by detecting the arc signal at the front welding wire end or the arc signal at the rear welding wire end. When the arc voltage signal at the front welding wire end is 0v, the welding wire position is the front welding wire molten droplet transfer position; when the arc voltage signal at the rear welding wire end is 0v, the welding wire position is the rear welding wire molten droplet transfer position.

4. The high-efficiency GTAW welding method with alternating longitudinal oscillation of two front and rear wires according to claim 1, characterized in that: The double-wire alternating oscillation welding wire frequency control method is used to control the oscillation frequency of the front wire feed slider and the oscillation frequency of the rear wire feed slider; in the front or rear end molten droplet growth stage, the front end molten droplet growth time t1 and the rear end molten droplet growth time t2 are calculated using the molten droplet growth time calculation method; in the front or rear end molten droplet transition stage, the molten droplet transition detection method is used to detect whether the molten droplet transition stage Z is completed, thereby realizing the control of the double-wire alternating oscillation welding wire frequency; the molten droplet growth time calculation method is to pre-set the mass m1 of each molten droplet of the front welding wire and the mass m2 of each molten droplet of the rear welding wire; the front welding wire molten droplet growth time t1 = m1 / (ρ1πr1v1); the rear welding wire molten droplet growth time t2 = m2 / (ρ2πr2v2); wherein ρ1 is The front welding wire density, ρ2 is the rear welding wire density, r1 is the front welding wire radius, r2 is the rear welding wire radius, v1 is the front welding wire filling speed, and v2 is the rear welding wire filling speed; the droplet transition detection method is realized by detecting the arc signal at the front welding wire end and the arc signal at the rear welding wire end. After the molten droplet growth time of the current welding wire ends, the front welding wire is controlled to move downward to the molten droplet transition position. When the arc signal at the current welding wire end is greater than 0v again, the front molten droplet transition stage ends, and the front welding wire is controlled to move upward to the optimal melting position; when the molten droplet growth time of the rear welding wire ends, the rear welding wire is controlled to move downward to the molten droplet transition position. When the arc signal at the rear welding wire end is greater than 0v again, the rear molten droplet transition stage ends, and the rear welding wire is controlled to move upward to the optimal melting position.

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