CN108555421B

CN108555421B - Molten drop transition control device based on pulse coordination double-tungsten-electrode argon arc welding and control method thereof

Info

Publication number: CN108555421B
Application number: CN201810285368.5A
Authority: CN
Inventors: 苗玉刚; 郭俊良; 李春旺; 马照伟; 韩端锋
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2018-04-03
Filing date: 2018-04-03
Publication date: 2020-06-16
Anticipated expiration: 2038-04-03
Also published as: CN108555421A

Abstract

The invention aims to provide a molten drop transition control device based on pulse coordination double-tungsten-electrode argon arc welding and a control method thereof. The method is different from the traditional control or thermal control depending on single motion mechanics, breaks through the traditional concept that the conventional consumable electrode arc welding droplet transition depends on the current magnitude, and provides a new means for the active control of the droplet transition.

Description

Molten drop transition control device based on pulse coordination double-tungsten-electrode argon arc welding and control method thereof

Technical Field

The invention relates to a welding device and a welding method thereof.

Background

The form of molten drop transition, the molten drop form, the transition frequency and the like have important influences on the welding quality, and the control of the molten drop transition process of welding is one of important ways for realizing the optimization of the welding quality. Researches show that the form and transition form of the molten drop not only have important influence on the application range of the welding process, but also influence the temperature distribution of electric arc and the heat distribution of workpieces, thereby being closely related to the welding quality problems of stability in the welding process, structural crystallization and mechanical property of welding seams, welding residual stress and the like; secondly, the form of droplet transfer, droplet morphology and transfer frequency also determine the weld surface roughness, weld formation accuracy and the amount of weld spatter.

In the conventional consumable electrode arc welding, because the melting and transition forms of the welding wires are directly related to the current magnitude, the melting speed of the welding wires and the molten drop transition are difficult to be independently controlled; although the Cold Metal Transition (CMT) technology realizes stable droplet transition under low current, the technology is only limited to a short circuit transition form, and the problems that the welding wire melting and the transition form are directly related to the current magnitude exist; the non-consumable electrode arc welding (TIG) technology has the problems of limited wire feeding position, low deposition efficiency and the like.

Disclosure of Invention

The invention aims to provide a molten drop transition control device based on pulse coordination double tungsten electrode argon arc welding and a control method thereof, which are based on the angle consideration of improving the weld forming precision, reducing the heat input, controlling the molten drop transition and the like.

The purpose of the invention is realized as follows:

the invention relates to a molten drop transition control device based on pulse coordination double tungsten electrode argon arc welding, which is characterized in that: the welding device comprises a first TIG arc welding power supply, a second TIG arc welding power supply, a first tungsten electrode, a second tungsten electrode, an IGBT shunt module, a first current signal detection device and a second current signal detection device, wherein the negative electrode of the first TIG arc welding power supply is connected with the first tungsten electrode, the negative electrode of the second TIG arc welding power supply is connected with the second tungsten electrode, and the positive electrodes of the first TIG arc welding power supply and the second TIG arc welding power supply are connected with a workpiece to form a welding current loop; the welding wire contact tip is connected with the positive electrodes of the first TIG arc welding power supply and the second TIG arc welding power supply through the IGBT shunt module to form a shunt bypass, the first current signal detection device detects current pulses of the first tungsten electrode, and the second current signal detection device detects current pulses of the welding wire.

The invention relates to a molten drop transition control method based on pulse coordination double tungsten electrode argon arc welding, which is characterized by comprising the following steps of: adopt the aforesaid molten drop transition controlling means based on two tungsten electrode argon arc welding of pulse coordination:

(1) placing a double-tungsten-electrode argon arc welding gun consisting of a first tungsten electrode, a second tungsten electrode and a wire feeder at a welding starting position, wherein the double-tungsten-electrode argon arc welding gun is vertical to a workpiece;

(2) setting pulse peak current, base current, arc voltage, shielding gas flow, pulse frequency and moving speed, and setting the current pulse frequency and the duty ratio of the first TIG arc welding power supply and the second TIG arc welding power supply to be consistent before welding;

(3) in the welding process, a first current signal detection device is used for detecting the arc pulse waveform of a first tungsten electrode, and when the current of the arc is detected to be at a pulse basic value, the current pulse of a second tungsten electrode is adjusted to be a pulse peak value through a pulse coordination controller; and when the voltage of the first tungsten electrode is detected to be at the pulse peak value, adjusting the current pulse of the second tungsten electrode to be a basic value through a pulse coordination controller, and repeating the process until the welding is finished.

The invention has the advantages that:

1. in the welding process, a pulse coordination control method is adopted, and the pulse frequency of two pulse TIG power supplies is regulated and controlled, so that the transition of molten drops is promoted, the transition forms of short-circuit liquid bridges, drop ejection, jet flow and the like of the molten drops are changed, and a welding joint with attractive appearance, few welding defects and high welding seam quality can be obtained.

2. Welding wires are fed into the centers of the symmetrical double tungsten electrodes in a TOPTIG mode, and compared with TIG paraxial wire feeding, the welding wire feeding device has no directionality, so that the welding flexibility is improved; compared with the MIG wire feeding speed and the current which are not related, the method is beneficial to the control of the weld forming. And the change gradient of the cross section area of the coupling arc is reduced by adjusting the form of the coupling arc, so that the electromagnetic force action is more uniform, the molten drop transition is more stable, and the accurate control of the molten drop transition is facilitated.

3. The welding wire can be shunted when the tungsten electrode and the base metal form a main path, the magnitude of the current flowing into the base metal is adjusted through the IGBT shunt module, the accurate control of the heat input of the base metal is realized, the heat affected zone of the base metal is narrowed, the deformation of components is reduced, namely, the deformation correcting process is reduced, the production cost is reduced, and the welding technology is low in heat input and high in efficiency.

4. The equipment is simple, the applicability is strong, and the method can be used for controlling the molten drop transition of welding of different metal materials.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the principle of molten drop stress;

FIG. 3 is a schematic diagram of a first TIG arc welding power supply pulse current signal;

fig. 4 is a schematic diagram of a pulse current signal of a second TIG arc welding power supply.

Detailed Description

The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:

referring to fig. 1-4, the welding device of the invention comprises a double tungsten electrode argon arc welding gun 3, argon tungsten

electrode power supplies

1 and 7, a wire feeder 4,

current signal detectors

12 and 14, a signal processor (PLC or single chip microcomputer) 10, a signal controller 9, an IGBT shunt module 8 and the like. During welding, the negative electrode of a TIG arc welding power supply 1 is connected with a tungsten electrode 2, the negative electrode of a TIG arc welding power supply 7 is connected with a tungsten electrode 6, the positive electrodes of the TIG arc

welding power supplies

1 and 7 are connected with a workpiece 13, and a welding wire contact nozzle is connected with the positive electrode of the TIG arc welding power supply through an IGBT shunt module 8. In this way, the TIG arc welding power supply 1 and the TIG arc welding power supply 7 have the negative electrode connected with the tungsten electrode and the positive electrode connected with the workpiece 13 to form a TIG welding current loop; the welding wire contact tip is connected with a TIG arc welding power supply through an IGBT shunt module to form an arc hot wire or a shunt bypass, so that the welding wire melting efficiency is improved, and the heat input and heat affected zone of the base metal is reduced. In the welding process, current pulses flowing through the welding wire and the tungsten electrode on one side are respectively detected by the current

signal detection devices

12 and 14, and the current pulse signals of the two tungsten electrodes are coordinately controlled by the pulse coordination controller 11, so that dynamic arc hybrid welding between TOPTIG (top tungsten inert gas) of the double tungsten electrodes and arc of the bypass shunt consumable electrode is realized, and efficient and accurate molten drop control is realized.

The molten drop transition control method based on the pulse coordination double tungsten electrode argon arc welding of the embodiment comprises the following steps:

step 1, mounting and positioning a workpiece 13 to be welded, and placing a double-tungsten electrode argon arc welding gun at a welding starting position, wherein the welding gun is perpendicular to the workpiece. The welding experimental equipment and the device are connected in the manner shown in fig. 1.

Step 2: and adjusting parameters such as the position of the workpiece, the distance between the welding gun and the workpiece, the included angle and the like according to the welding process requirements. According to the welding requirements, various welding process parameters such as pulse peak current, base value current, arc voltage, protective gas flow, pulse frequency, moving speed and the like are set. Before welding, the current pulse frequency and the duty ratio of the TIG arc

welding power sources

1 and 7 are set to be the same.

And step 3: during welding, the current signal detector 14 detects the arc pulse waveform of one tungsten electrode, when the current of the arc is detected to be at the pulse base value, the pulse coordination controller 11 adjusts the current pulse of the other tungsten electrode to be at the pulse peak value, when the voltage of the arc is detected to be at the pulse peak value, the pulse coordination controller adjusts the current pulse of the other tungsten electrode to be at the base value, and the steps are repeated. By setting the current frequency and amplitude of the tungsten electrode arc pulse, the accurate and efficient control of the droplet transition form is realized.

The invention comprises two pulse TIG power supplies, an IGBT shunt module, a wire feeding mechanism, a double-tungsten electrode argon arc welding gun, a pulse coordination control system and the like. Two tungsten electrodes of the double-tungsten electrode argon arc welding gun are respectively connected with the negative electrodes of two pulse TIG power supplies, and the two welding power supplies are connected through a signal detection and control system. In the welding process, a pulse coordination control method is adopted, namely when the arc current of one TIG welding gun is in a pulse basic value pilot arc, a pulse signal controller is triggered, the arc current of the other TIG welding gun is adjusted to be in a pulse peak value pilot arc, a coupling magnetic field formed by two tungsten electrodes is led by the side at the peak value, and repulsive force is generated on a falling molten drop to enable the falling molten drop to deviate towards the tungsten electrode at the basic value side. When the peak value and the valley value of the current pulse of the tungsten electrode are alternated, the direction of the magnetic field is also changed, so that the molten drop is subjected to repulsion in the opposite direction. When the frequency of the square wave pulse is high enough, the positive and negative alternation of the coupling magnetic field between the two tungsten electrodes is fast enough, and the molten drop can not shift left and right but directly fall, thereby achieving the effect of controlling the transition of the molten drop. The welding wire is fed into the center of the symmetrical double tungsten electrode in a TOPTIG mode, has no directivity compared with TIG paraxial wire feeding, is not related to the current compared with MIG wire feeding speed, and the formation of the coupling arc is favorable for accurately controlling the molten drop transition; the total current of the pulse TIG power supply flows through the double-tungsten electrode argon arc welding gun, the welding wire is shunted when the TOPTIG welding gun and a workpiece form a main circuit, and the current flowing through the tungsten electrode of the main circuit is divided into two parts during welding, wherein one part is the current flowing back to the pulse TIG power supply through a bypass, and the other part is the current applied to a base metal. In addition, the method uses a direct current pulse power supply, has simple equipment, reduces the welding cost, and is a new technology for controlling the excessively low molten drop with high efficiency and low cost.

Claims

1. A molten drop transition control device based on pulse coordination double tungsten electrode argon arc welding is characterized in that: the device comprises a first TIG arc welding power supply, a second TIG arc welding power supply, a first tungsten electrode, a second tungsten electrode, an IGBT shunt module, a first current signal detection device, a second current signal detection device and a pulse coordination controller, wherein the negative electrode of the first TIG arc welding power supply is connected with the first tungsten electrode, the negative electrode of the second TIG arc welding power supply is connected with the second tungsten electrode, and the positive electrodes of the first TIG arc welding power supply and the second TIG arc welding power supply are connected with a workpiece to form a welding current loop; the welding wire contact tip is connected with the positive electrodes of a first TIG arc welding power supply and a second TIG arc welding power supply through an IGBT shunt module to form a shunt bypass, the first current signal detection device detects current pulses of a first tungsten electrode, the second current signal detection device detects current pulses of a welding wire, and the pulse coordination controller is used for carrying out coordination control on current pulse signals of the first tungsten electrode and the second tungsten electrode.

2. A molten drop transition control method based on pulse coordination double tungsten electrode argon arc welding is characterized in that: the molten drop transition control device based on the pulse coordination double tungsten electrode argon arc welding as claimed in claim 1 is adopted: