Closed-loop control method of temperature field in narrow gap weld based on magnetically controlled GTAW arc

Abstract

The present invention relates to the field of GTAW arc control, and is a closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc. In view of the adverse effects of unreasonable heat input distribution on both sides of a narrow gap on weld formation during the GTAW process, a closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc is proposed. A GTAW robot is used to control the welding action; a magnetic field generator is used to control the distribution of the weld temperature field by controlling the parameters of the magnetic field; and a weld left and right temperature detection system is used to detect the left and right temperatures of the weld.

Description

Technical Field

[0001] The invention relates to the field of GTAW arc control, and is a closed-loop control method for narrow gap weld temperature field based on magnetically controlled GTAW arc. Background Art

[0002] GTAW (gas shielded welding) is widely used in aerospace, marine equipment, nuclear power construction and other fields. Especially in recent years, with the rapid development of science and technology, higher requirements have been put forward for component performance, and magnetically controlled GTAW has also developed in a more intelligent direction. In the GTAW narrow gap welding process, the temperature distribution of the weld has a crucial influence on the weld quality. When the temperature is unreasonable, the welding process is unstable, and welding defects such as cracks may occur in the weld. In response to the above difficulties, the present invention discloses a GTAW temperature field closed-loop control method based on a magnetic field, which improves the stability of the welding process and the quality of the weld by controlling the timing of the magnetic field and the welding action of the GTAW robot during the welding process. Summary of the invention

[0003] A closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc is used to control the temperature field distribution of the weld during the GTAW process to obtain better welding quality. It is characterized in that: the closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc is realized by using a closed-loop control system for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc; the closed-loop control system for the temperature field of a narrow gap weld based on a magnetic field GTAW arc is composed of a GTAW robot, a magnetic field generator, and a left and right temperature detection system for the weld; the GTAW robot is used to control the welding action; the magnetic field generator controls the temperature field distribution of the weld; and the left and right temperature detection system for the weld is used to detect the temperature on the left and right sides of the weld. The data obtained by the left and right temperature detection systems of the weld are used to control the GTAW robot and the magnetic field generator, so that the welding speed and the magnetic field timing are changed to achieve the purpose of controlling the temperature field of the narrow gap weld. The schematic diagram of the magnetic field controlling the arc deflection of the narrow gap weld is shown in the figure. Figure 1 As shown in the figure. The closed-loop control system of temperature field of narrow gap weld based on magnetically controlled GTAW arc is shown in the figure. Figure 2 shown.

[0004] The closed-loop control method of the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc controls the left and right temperature detection systems of the weld; the left and right temperature detection systems of the weld are fixed by a clamp on the welding gun and can move synchronously with the welding gun; the left and right temperature detection systems of the weld are composed of an infrared thermal imaging device and an image processing system; the infrared thermal imaging device is composed of an infrared camera for detecting the temperature field of the weld and a moving rod; the up and down adjustment of the infrared camera can be achieved by changing the position of the clamp on the welding gun, and the front, back, left and right adjustment of the infrared camera can be achieved by adjusting the moving rod; the infrared camera adjustment position should be able to fully capture the weld temperature field; set before welding begins n is the number of images transmitted per unit time, L is the welding distance, v is the welding speed, and m is the number of images taken at the welding distance L. After n is set, it remains fixed, and m changes linearly with the change of v. The image processing system receives the image from the infrared thermal imaging device and divides the infrared image into left and right parts along the center line of the weld for processing. After the infrared image is processed, the temperature T on the left side of the weld will be obtained. l , the temperature on the right side of the weld is T r and the average temperature on both sides Select the highest temperature point on the left and right parts of the infrared image as the center of the circle, select a circle that is large enough to contain N pixels, and calculate the average temperature of all pixels to get T. l and T r , T l and T r The value can be obtained by Find T li is the temperature of the i-th pixel on the left, T ri is the temperature of the i-th pixel on the right.

[0005] The invention discloses a closed-loop control method for temperature field of narrow gap weld based on magnetically controlled GTAW arc, characterized in that: the closed-loop control method for temperature field of narrow gap weld based on magnetically controlled GTAW arc is used to control the timing of excitation current in the magnetic field generator; the magnetic field generator is composed of a magnetic field generating device and a magnetic field control device; the magnetic field generating device is a front and rear magnetic field generating device parallel to the welding direction, fixedly connected to the welding gun, the front and rear magnetic field generating device is composed of two solenoids, and the magnetic field formed by the two solenoids is parallel to the welding direction; the magnetic field control device can control the magnitude of the magnetic field by adjusting the magnitude of the excitation current, and control the deflection angle of the arc by controlling the magnitude of the magnetic field; the magnetic field control device can control the deflection time of the arc on both sides of the parent material by changing the timing of the magnetic field, thereby affecting the temperature of the parent material on the control side; the excitation current timing is divided into a current duration T1 that makes the arc deflect to the left and a current duration T2 that makes the arc deflect to the right; before welding starts, the coil current magnitude I is set 设 , the magnetic field generation and control system maintains the initial state, and the magnetic field generation device generates a magnitude of B = μ0nI in the initial state设 The magnetic field, μ0 is the magnetic permeability in vacuum, n is the number of turns, I 设 is the preset excitation current size; after welding starts, the magnetic field control device obtains the signal transmitted by the temperature detection system on the left and right sides of the weld through the communication bus, and the magnetic field control device controls the timing of the excitation current by analyzing the signal; the minimum threshold value T of the left side temperature of the weld is set Lmin , the maximum threshold T Lmax , right side temperature minimum threshold T Rmin , the maximum threshold T Rmax , when T l <T Lmin When T1 is extended, T l >T Lmax When T1 is shortened, T Lmin <T l <T Lmax When T1 is unchanged, T r <T Rmin When T2 is extended, T r >T Rmax When T2 is shortened, T Rmin <T r <T Rmax When T2 is constant, the current waveform is as follows: Figure 4 shown.

[0006] The invention discloses a closed-loop control method for temperature field of narrow gap weld based on magnetically controlled GTAW arc, which is characterized in that: the welding speed of GTAW robot is controlled by using the closed-loop control method for temperature field of narrow gap weld based on magnetically controlled GTAW arc; after welding starts, the magnetic field control device obtains the signal transmitted by the left and right temperature detection systems of the weld through the communication bus, and the GTAW robot controls the welding speed of the GTAW robot by analyzing the signal; the maximum threshold value of the average temperature on the left and right sides is set as T max , the minimum threshold value of the average temperature on the left and right sides T min ,like The welding speed increases, The welding speed is reduced when The welding speed remains constant.

[0007] Advantageous Effects of the Invention

[0008] The present invention relates to the field of GTAW arc control, and is a closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc. In view of the adverse effects of unreasonable heat input distribution on both sides of a narrow gap on weld formation during the GTAW process, a closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc is proposed. A GTAW robot is used to control the welding action; a magnetic field generator is used to control the distribution of the weld temperature field by controlling the parameters of the magnetic field; and a weld left and right temperature detection system is used to detect the left and right temperatures of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 Schematic diagram of magnetic field-controlled arc deflection in narrow gap welding.

[0010] Figure 2 It is a closed-loop control system for the temperature field of narrow gap welds based on the magnetron GTAW arc. The front base material is made transparent for easy viewing.

[0011] Figure 3 This is a flow chart of the closed-loop control method of temperature field in narrow gap welds based on magnetically controlled GTAW arc.

[0012] Figure 4 It is the current waveform diagram. DETAILED DESCRIPTION

[0013] 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.

[0014] Step 1: Welding speed control.

[0015] The GTAW temperature field is controlled by controlling the welding speed. During the magnetically controlled GTAW narrow gap welding process, the welding speed needs to be controlled in real time. If the welding speed is too fast, the heat input per unit length of the weld will be reduced, resulting in a decrease in the mechanical properties of the welded joint; if the welding speed is too slow, the heat input per unit degree will increase, resulting in welding defects. In response to this problem, the present invention discloses a closed-loop control method for the weld temperature field based on the narrow gap welding speed of the magnetically controlled GTAW arc. After the welding starts, Figure 2 The temperature detection system on the left and right sides of the weld starts to collect temperature data and calculates the and the temperature T of the base material l and T l , and transmitted to the magnetic field control device through the communication bus. The magnetic field control device will With preset T min and T max Compare and control the welding speed of the GTAW robot by controlling the bus until Where T min and T max It is a preset threshold value based on the temperature field distribution, so that the total heat input per unit length of the narrow gap weld will not be too high or too low.

[0016] Step 2: Excitation current timing control.

[0017] The GTAW temperature field is controlled by controlling the timing of the excitation current. During the magnetically controlled GTAW narrow gap welding process, the excitation current timing needs to be controlled in real time. If the time is short, the heat input on one side of the arc deflection will be insufficient, resulting in poor weld formation; if the time is long, the heat input on one side of the arc deflection will be excessive, resulting in reduced weld strength and toughness. To address this problem, the present invention discloses a closed-loop control method for the weld temperature field based on the narrow gap excitation current timing of the magnetically controlled GTAW arc. After the welding starts, Figure 2 The temperature detection system on the left and right sides of the weld starts to collect temperature data and calculates the and the temperature T of the base material l and T r , and transmits it to the magnetic field control device through the communication bus. The magnetic field control device will r With preset T Rmin and T Rmax For comparison, T l With preset T Lmin and T Lmax By comparing, the retention time of magnetic field deflection is controlled by controlling the timing of the excitation current in the magnetic field generating device until T Rmin <T r <T Rmax and T Lmin <T l <T Lmax , where T Rmin and T Rmax , T Lmin and T Lmax It is a threshold value preset according to the temperature field distribution, so that the heat input of the left and right parent materials is consistent with the properties of the left and right parent materials.

Claims

1. A closed-loop control method for the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc is used to control the temperature field distribution of the weld during the GTAW process to obtain better welding quality, and is characterized by: The narrow gap weld temperature field closed-loop control method based on magnetically controlled GTAW arc is realized by using the narrow gap weld temperature field closed-loop control system based on magnetically controlled GTAW arc; the narrow gap weld temperature field closed-loop control system based on magnetically controlled GTAW arc is composed of a GTAW robot, a magnetic field generator, and a weld left and right temperature detection system; the GTAW robot is used to control welding action; the magnetic field generator controls the weld temperature field distribution; the weld left and right temperature detection system is used to detect the temperature on the left and right sides of the weld; the weld left and right temperature detection system is fixed by a clamp on the welding gun and can move synchronously with the welding gun; the weld left and right temperature detection system is composed of an infrared thermal imaging device and an image processing system; the infrared thermal imaging device is composed of an infrared camera for detecting the weld temperature field and a moving rod; the up and down adjustment of the infrared camera is achieved by changing the position of the clamp on the welding gun, and the front, back, left and right adjustment of the infrared camera is achieved by adjusting the moving rod; the infrared camera adjustment position should be able to fully capture the weld temperature field; set before welding starts n is the number of images transmitted per unit time, L is the welding distance, v is the welding speed, and m is the number of images taken at the welding distance L; the image processing system receives the image from the infrared thermal imaging device, divides the infrared image into two parts along the center line of the weld for processing; after processing, the infrared image will obtain the temperature T of the left side of the weld l , right side temperature of weld T r and the average temperature on both sides Select the highest temperature point on the left and right parts of the infrared image as the center of the circle, select a circle that is large enough to contain N pixels, and calculate the average temperature of all pixels to get T. l and T r , T l and T r The value can be obtained by Find T li is the temperature of the i-th pixel on the left, T ri is the temperature of the position of the i-th pixel point on the right; the closed-loop control method of the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc uses the closed-loop control method of the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc to control the timing of the excitation current in the magnetic field generator; the magnetic field generator is composed of a magnetic field generating device and a magnetic field control device; the magnetic field generating device is a front and rear magnetic field generating device parallel to the welding direction, fixedly connected to the welding gun, and the front and rear magnetic field generating devices are composed of two solenoids, and the magnetic field formed by the two solenoids is parallel to the welding direction; the magnetic field control device controls the magnitude of the magnetic field by adjusting the magnitude of the excitation current, and controls the deflection angle of the arc by controlling the magnitude of the magnetic field; the magnetic field control device controls the deflection time of the arc on both sides of the parent material by changing the timing of the magnetic field, thereby controlling the temperature of the parent material on both sides; the timing of the excitation current is divided into a current duration T1 that makes the arc deflect to the left and a current duration T2 that makes the arc deflect to the right; before welding starts, the excitation current magnitude I is preset 设 , the magnetic field generating device and the magnetic field control device maintain the initial state, and the magnetic field generating device generates a magnitude of B = μ0nI in the initial state. 设 The magnetic field, μ0 is the magnetic permeability in vacuum, n is the number of turns, I 设 is the preset excitation current size; after welding starts, the magnetic field control device obtains the signal transmitted by the temperature detection system on the left and right sides of the weld through the communication bus, and the magnetic field control device controls the timing of the excitation current by analyzing the signal; the minimum threshold value T of the left side temperature of the weld is set Lmin , the maximum threshold T Lmax , right side temperature minimum threshold T Rmin , the maximum threshold T Rmax , when T l <T Lmin When T1 is extended, T l >T Lmax When T1 is shortened, T Lmin <T l <T Lmax When T1 is unchanged, T r <T Rmin When T2 is extended, T r >T Rmax When T2 is shortened, T Rmin <T r <T Rmax , T2 remains unchanged.

2. The closed-loop control method for temperature field of narrow gap weld based on magnetically controlled GTAW arc according to claim 1, characterized in that: The GTAW robot welding speed is controlled by a closed-loop control method of the temperature field of a narrow gap weld based on a magnetically controlled GTAW arc. After welding begins, the magnetic field control device obtains the signal transmitted by the temperature detection systems on the left and right sides of the weld through the communication bus, and the GTAW robot controls the welding speed of the GTAW robot by analyzing the signal. The maximum threshold of the average temperature on the left and right sides is set as T. max , the minimum threshold value of the average temperature on the left and right sides T min ,like The welding speed increases, The welding speed is reduced when The welding speed remains constant.

Images