Longitudinal oscillation wire filling method for GTAW welding wire based on arc sensing

Abstract

Abstract: The present invention relates to the field of GTAW welding wire filling control, and is a GTAW welding wire filling method with longitudinal oscillation based on arc sensing. In view of the adverse effects of the filler wire position being too low or too high on the weld formation during the GTAW welding process, a GTAW welding wire filling method with longitudinal oscillation based on arc sensing is proposed. The longitudinal oscillation amplitude control method of the GTAW welding wire with filler wire is used to control the longitudinal oscillation amplitude of the welding wire; the longitudinal oscillation frequency control method of the GTAW welding wire with filler wire is used to control the longitudinal oscillation frequency of the welding wire; and the longitudinal oscillation amplitude and frequency of the welding wire are controlled by a welding wire longitudinal oscillation control mechanism.

Description

Technical Field

[0001] The invention relates to the field of GTAW welding wire filling control, and is a GTAW welding wire longitudinal oscillation filling method based on arc sensing. 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 GTAW with filler wire. In the GTAW process with filler wire, the position of the filler wire has a crucial influence on the weld formation. When the filler wire position is too high, the welding process is unstable; when the filler wire position is too low, the melting rate of the welding wire will be reduced. In response to the above difficulties, the present invention discloses a longitudinal oscillation filling method for GTAW welding wire with filler wire based on arc sensing. By controlling the longitudinal oscillation of the welding wire during the welding process, the stability of the welding process and the quality of the weld are improved. Summary of the invention

[0003] The arc sensing-based GTAW welding wire longitudinal oscillation filling method is used to control the longitudinal oscillation of the welding wire during the GTAW filling process to obtain higher deposition efficiency and better welding quality, and is characterized in that: the arc sensing-based GTAW welding wire longitudinal oscillation filling method is implemented based on the GTAW welding arc temperature distribution characteristics; the GTAW welding arc temperature distribution characteristics are that in the GTAW welding arc, the cathode and anode areas have lower temperatures, while the arc column area has higher temperatures, and the closer to the tungsten electrode, the higher the temperature. The schematic diagram of the GTAW welding arc temperature distribution is as follows Figure 1 shown.

[0004] The arc sensing-based GTAW welding wire longitudinal oscillation filling method is characterized in that: the arc sensing-based GTAW welding wire longitudinal oscillation filling method is realized by utilizing the arc sensing-based GTAW welding wire longitudinal oscillation filling control system; the arc sensing-based GTAW welding wire longitudinal oscillation filling control system is composed of a GTAW welding robot, a welding wire longitudinal oscillation control mechanism, and an arc signal acquisition system; the GTAW welding robot is used to control the welding gun for welding; the welding wire longitudinal oscillation control mechanism is used to control the frequency and amplitude of the welding wire longitudinal oscillation; the arc signal acquisition system is used to collect the tungsten extreme arc signal and the welding wire end arc signal; the tungsten extreme arc signal is the arc voltage between the tungsten electrode and the workpiece; the welding wire end arc signal is the arc voltage between the welding wire and the workpiece. The schematic diagram of the arc sensing-based GTAW welding wire longitudinal oscillation filling control system is shown in the figure. Figure 2 shown.

[0005] The invention discloses a longitudinal oscillation filling method for GTAW welding wire based on arc sensing, characterized in that: the longitudinal oscillation amplitude of the welding wire is controlled by using a longitudinal oscillation amplitude control method for GTAW welding wire; the longitudinal oscillation amplitude control method for GTAW welding wire controls the welding wire to move upward to an optimal melting position during the droplet growth stage, and controls the welding wire to move downward to a droplet transition position during the droplet transition stage, so that the welding wire contacts the molten pool and completes the droplet transition; the optimal melting position is obtained by calculating the arc voltage U w The arc voltage U at the welding wire end h Difference U w -U h To find, when ΔU min ≤U w -U h ≤ΔU max When ΔU min With ΔU max The threshold value preset according to the welding arc temperature distribution ensures that the welding wire is in the highest temperature area while avoiding adhesion due to being too close to the tungsten electrode; the droplet transition position is determined by real-time detection of the arc voltage U at the welding wire end. h Come to find, when U h =0, the wire position is the droplet transition position.

[0006] The invention discloses a longitudinal oscillation filling method for GTAW welding wire based on arc sensing, characterized in that: the longitudinal oscillation frequency of the welding wire is controlled by using a longitudinal oscillation frequency control method for the GTAW welding wire; the longitudinal oscillation frequency control method for the GTAW welding wire is to calculate the molten droplet growth time t1 by using a molten droplet growth time calculation method in the molten droplet growth stage, and to detect whether the molten droplet transition stage is completed by using a molten droplet transition detection method in the molten droplet transition stage, thereby realizing the control of the longitudinal oscillation frequency of the welding wire; the molten droplet growth time calculation method is realized by presetting the mass m of each molten droplet, and the molten droplet transition time t1=m / (ρπr 2 v), where ρ is the wire density, r is the wire radius, and v is the wire filling speed; the droplet transfer detection method is to detect the arc voltage U at the wire end h When the droplet growth time is over, the welding wire is controlled to move downward to the droplet transition position. When the arc voltage U h When it is greater than 0 again, the droplet transfer stage ends, and the welding wire is controlled to move upward to the optimal melting position.

[0007] The invention discloses a method for longitudinal oscillation of GTAW welding wire based on arc sensing, which is characterized in that: a longitudinal oscillation control mechanism of the welding wire is used to control the longitudinal oscillation amplitude and frequency of the welding wire; the longitudinal oscillation control mechanism of the welding wire is composed of a longitudinal oscillation controller of the welding wire, a wire feeding tube, a clamping device, a movable shaft, a mounting mechanism, and a servo motor; the longitudinal oscillation controller of the welding wire is connected to an arc signal acquisition system through a communication bus, and drives a servo motor to control the movable shaft through a control bus, thereby driving the welding wire to realize longitudinal oscillation control; the wire feeding tube is used to transmit the welding wire; the clamping device is used to fix the wire feeding tube to the movable shaft; the movable shaft is connected to a GTAW welding gun through a mounting mechanism, thereby driving the longitudinal oscillation of the welding wire; the servo motor is fixed above the movable shaft, thereby controlling the movable shaft and thereby driving the longitudinal oscillation of the welding wire.

[0008] Advantageous Effects of the Invention

[0009] The invention relates to the field of GTAW welding wire control, and is a GTAW welding wire longitudinal oscillation filling method based on arc sensing. Aiming at the adverse effect of too low or too high position of the filler wire on weld formation during the GTAW welding process, a GTAW welding wire longitudinal oscillation filling method based on arc sensing is proposed. The longitudinal oscillation amplitude of the welding wire is controlled by the GTAW welding wire longitudinal oscillation amplitude control method; the longitudinal oscillation frequency of the welding wire is controlled by the GTAW welding wire longitudinal oscillation frequency control method; and the longitudinal oscillation amplitude and frequency of the welding wire are controlled by the welding wire longitudinal oscillation control mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the arc temperature distribution diagram of GTAW welding.

[0011] Figure 2 It is a longitudinal oscillation wire filling control system for GTAW welding wire based on arc sensing.

[0012] Figure 3 The flowchart of the longitudinal oscillation filling wire control method of GTAW welding wire based on arc sensing.

[0013] In the figure, t1=m / (ρπr 2 v), where ρ is the wire density, r is the wire radius, and v is the wire filling speed.

[0014] Figure 4 Schematic diagram of the longitudinal oscillation of the GTAW welding wire.

[0015] In the figure, U w is the tungsten terminal voltage, U h is the voltage at the welding wire end. DETAILED DESCRIPTION

[0016] 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.

[0017] Step 1: Control the longitudinal vibration amplitude of the welding wire.

[0018] In the process of GTAW with filler wire, the longitudinal position of the welding wire needs to be controlled in real time. If the longitudinal position of the welding wire is too high, the welding process will be unstable; if the longitudinal position of the welding wire is too low, the melting efficiency of the welding wire will decrease. In view of this problem, the present invention discloses a method for adaptively controlling the longitudinal oscillation amplitude of the GTAW welding wire with filler wire. After the welding starts, Figure 1 The arc signal acquisition system in the welding wire starts to collect arc signals and transmits them to the welding wire longitudinal oscillation controller through the communication bus. The welding wire longitudinal oscillation controller calculates the tungsten terminal voltage U in real time. w With the welding wire end voltage U h During the droplet growth stage, the servo motor is driven by the control bus to control the moving axis to drive the welding wire to move longitudinally until ΔU min ≤U w -U h ≤ΔU max , where ΔU min With ΔU max The threshold value is preset according to the arc temperature graduation, so that the welding wire is in the best melting position while avoiding adhesion due to being too close to the tungsten electrode; in the droplet transition stage, the welding wire is controlled to move downward until U h =0.

[0019] Step 2: Control the longitudinal oscillation frequency of the welding wire.

[0020] In the wire-filled GTAW process, it is necessary to reasonably control the droplet growth time and the droplet transition time to obtain better weld quality. To address this problem, the present invention discloses a method for controlling the longitudinal oscillation frequency of the wire in the wire-filled GTAW process. Figure 1 The wire longitudinal oscillation controller obtains the droplet growth time t1=m / (ρπr 2 v), where ρ is the wire density, r is the wire radius, and v is the wire filling speed. At the beginning of the droplet growth stage, the wire longitudinal oscillation controller drives the servo motor to control the wire to move longitudinally to the optimal melting position and stay for time t1; after the droplet growth stage ends (i.e., after time t1 ends), the wire longitudinal oscillation controller drives the servo motor through the control bus to control the wire to move downward until the wire terminal voltage U h = 0. When it is detected that the voltage Uh at the welding wire end is greater than 0 again, the welding wire is controlled to move upward back to the optimal melting position, and the above steps are repeated, thereby achieving the effect of controlling the longitudinal oscillation frequency of the welding wire during the welding process.

Claims

1. A method for longitudinal oscillation of GTAW welding wire based on arc sensing, which is used to control the longitudinal oscillation of the welding wire during the GTAW process, and is characterized by: The arc sensing-based GTAW welding wire longitudinal oscillation filling wire method is realized by using the arc sensing-based GTAW welding wire longitudinal oscillation filling wire control system; the arc sensing-based GTAW welding wire longitudinal oscillation filling wire control system is composed of a GTAW welding robot, a welding wire longitudinal oscillation control mechanism, and an arc signal acquisition system; the GTAW welding robot is used to control the welding gun for welding; the welding wire longitudinal oscillation control mechanism is used to control the frequency and amplitude of the welding wire longitudinal oscillation; the arc signal acquisition system is used to collect the tungsten extreme point arc signal and the welding wire end arc signal; the tungsten extreme point arc signal is the arc between the tungsten electrode and the workpiece voltage; the arc signal at the wire end is the arc voltage between the welding wire and the workpiece; the longitudinal oscillation filling method of the GTAW welding wire based on arc sensing is to control the longitudinal oscillation amplitude of the welding wire by using the longitudinal oscillation amplitude control method of the GTAW welding wire, and to control the longitudinal oscillation frequency of the welding wire by using the longitudinal oscillation frequency control method of the GTAW welding wire; the longitudinal oscillation amplitude control method of the GTAW welding wire is to control the welding wire to move upward to the optimal melting position during the droplet growth stage, and to control the welding wire to move downward to the droplet transition position during the droplet transition stage, so that it contacts the molten pool and completes the droplet transition; the optimal melting position is calculated by calculating the arc voltage U w The arc voltage U at the welding wire end h Difference U w -U h To find, when ΔU min ≤U w -U h ≤ΔU max When ΔU min With ΔU max The threshold value preset according to the welding arc temperature distribution ensures that the welding wire is in the highest temperature area while avoiding adhesion due to being too close to the tungsten electrode; the droplet transition position is determined by real-time detection of the arc voltage U at the welding wire end. h Come to find, when U h =0, then the wire position is the droplet transition position; the method for controlling the longitudinal oscillation frequency of the GTAW wire with filler wire is to calculate the droplet growth time t1 by using the droplet growth time calculation method in the droplet growth stage, and to detect whether the droplet transition stage is completed by using the droplet transition detection method in the droplet transition stage, thereby realizing the control of the longitudinal oscillation frequency of the welding wire; the droplet growth time calculation method is realized by presetting the mass m of each droplet, and the droplet transition time t1=m / (ρπr 2 v), where ρ is the wire density, r is the wire radius, and v is the wire filling speed; the droplet transfer detection method is to detect the arc voltage U at the wire end h When the droplet growth time is over, the welding wire is controlled to move downward to the droplet transition position. When the arc voltage U h When it is greater than 0 again, the droplet transfer stage ends, and the welding wire is controlled to move upward to the optimal melting position.

2. The method for longitudinal oscillation of GTAW welding wire based on arc sensing according to claim 1, characterized in that: A welding wire longitudinal oscillation control mechanism is used to control the amplitude and frequency of the welding wire longitudinal oscillation; the welding wire longitudinal oscillation control mechanism is composed of a welding wire longitudinal oscillation controller, a wire feeding tube, a clamping device, a moving shaft, a mounting mechanism, and a servo motor; the welding wire longitudinal oscillation controller is connected to an arc signal acquisition system via a communication bus, and drives a servo motor to control the moving shaft via the control bus, thereby driving the welding wire to achieve longitudinal oscillation control; the wire feeding tube is used to transmit the welding wire; the clamping device is used to fix the wire feeding tube to the moving shaft; the moving shaft is connected to a GTAW welding gun via a mounting mechanism, and is used to drive the welding wire to oscillate longitudinally; the servo motor is fixed above the moving shaft, and is used to control the moving shaft, thereby driving the welding wire to oscillate longitudinally.

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