CN108608126B

CN108608126B - Plasma shunting consumable electrode arc welding device and welding method

Info

Publication number: CN108608126B
Application number: CN201810303615.XA
Authority: CN
Inventors: 苗玉刚; 杨晓山; 刘吉; 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: 2021-01-05
Anticipated expiration: 2038-04-03
Also published as: CN108608126A

Abstract

The invention aims to provide a plasma shunt consumable electrode arc welding device and a welding method, which utilize a plasma welding gun nozzle as a bypass to shunt part of welding current passing through a base material when consumable electrode plasma arc welding is carried out. Therefore, the consumable electrode welding wire can be electrified with large current, the heat input acting on the base metal is reduced while the high deposition rate and the stable molten drop transition are realized, and the welding quality is improved; the plasma nozzle is connected with the cathode of the shunt electric arc, the burning loss of the nozzle can be greatly reduced and the bearing capacity of the welding gun can be improved only through partial current, and the advantages of low heat input of plasma shunt, high melting efficiency of plasma arc of a consumable electrode and stable welding process are combined in the stable welding process.

Description

Plasma shunting consumable electrode arc welding device and welding method

Technical Field

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

Background

Plasma arcs are arcs formed by external restraint such that the arc column of the arc is strongly constricted. Compared with the traditional electric arc, the electric arc temperature, the energy density and the plasma flow rate of the plasma arc are obviously increased, and the plasma arc has the advantages of large depth-width ratio of a welding line, narrow heat affected zone, small deformation of a workpiece and the like. The metal argon arc welding (MIG welding) has the advantages of high welding wire melting efficiency, wide range of weldable metal and the like and is widely applied. In order to combine the technical advantages of a consumable electrode and a plasma arc, a plasma-consumable electrode composite heat source welding method is provided by W.G.essers, A.C.Liefkens and the like of Philips research center of the Netherlands. Patent No. CN103817449A proposes a plasma arc and consumable electrode arc hybrid welding method and welding device, which are characterized in that: and in the welding direction, the front end adopts plasma arc to preheat a workpiece to be welded or weld joint penetration, and the rear end adopts consumable electrode arc to melt a welding wire and fill the weld joint. In the method, the plasma nozzles and the consumable electrode nozzles are arranged in the protective cover of the composite welding gun in a front-back sequence and in a single row along the welding direction, so that the welding gun has a complex structure and a large volume, brings difficulty to the replacement and daily maintenance of related elements, and is not beneficial to actual welding operation. The plasma arc welding method of the consumable electrode has many advantages, but also has some defects, which are mainly shown in the following: (1) when the plasma arc welding of the consumable electrode is carried out, the plasma arc and the MIG arc are simultaneously combusted in the welding gun, and the welding gun nozzle is connected with the anode of the power supply, so that the temperature of the welding gun nozzle is very high, higher requirements on water cooling are provided, and the double-arc gun burning phenomenon encountered by the common plasma gun is avoided due to the fact that the design of all parameters in the gun body is reliable, so that the cavity structure is complex, and the volume and the weight are large. (2) When the plasma arc welding of the consumable electrode is carried out, in order to improve the welding efficiency, the welding current of the plasma arc and the MIG electric arc needs to be increased, so that the heat input of a workpiece is larger, the problems of large welding deformation, poor structural performance and the like are easily caused.

Disclosure of Invention

The invention aims to provide a plasma shunting consumable electrode arc welding device and a welding method which can reasonably distribute heat acting on a base metal and a welding wire, reduce welding gun burning loss when a plasma nozzle is connected with an anode, improve welding quality, reduce welding deformation, and solve the problems of difficult arc striking of a plasma-consumable electrode composite arc and the like.

The purpose of the invention is realized as follows:

the invention relates to a plasma shunting consumable electrode arc welding device, which comprises an MIG power supply, a shunting module, a plasma shunting consumable electrode arc welding gun, a current sensor and a control system, wherein the MIG power supply is connected with the shunting module; the plasma shunting consumable electrode arc welding gun comprises a wire feeding mechanism, an MIG welding conductive nozzle, an insulating protective porcelain bushing, an annular plasma electrode, a plasma confinement nozzle and a protective gas shield, wherein a welding wire extends into the MIG welding conductive nozzle through the wire feeding mechanism, the MIG welding conductive nozzle is positioned in the insulating protective porcelain bushing, the annular plasma electrode is connected with a water-cooling copper bushing through threads, the annular plasma electrode and the water-cooling copper bushing are positioned outside the insulating protective porcelain bushing, the plasma confinement nozzle is arranged outside the annular plasma electrode, and the protective gas shield is arranged outside the plasma confinement nozzle; the positive pole of MIG power connects the welding wire, and the work piece is connected to the negative pole of MIG power, and the welding wire is connected to the positive pole of reposition of redundant personnel module, and the water-cooling copper sheathing is connected to the negative pole of reposition of redundant personnel module, and current sensor connects the electric current that detects the parent metal and connects control system, and control system connects and adjusts the resistance of reposition of redundant personnel module.

The plasma split-flow consumable electrode arc welding apparatus of the present invention may further comprise:

1. the water-cooled copper sleeve is provided with cooling water, an ion gas channel is formed between the water-cooled copper sleeve and the connector of the annular plasma electrode and the insulating protective porcelain sleeve, and a protective gas channel is formed between the plasma confinement nozzle and the protective gas cover.

2. After the MIG power supply is turned on and the wire feeding mechanism is started, MIG electric arc is generated at the end of the welding wire, a loop is formed between the annular plasma electrode and the welding wire, the ion gas is ignited to form bypass plasma electric arc, and the bypass plasma electric arc is coupled with the MIG electric arc to form composite electric arc.

The invention relates to a plasma shunting consumable electrode arc welding method, which adopts the plasma shunting consumable electrode arc welding device:

(1) before welding, processing a workpiece, including cleaning an oxide film on the surface of a base metal and beveling;

(2) adjusting the angle between the axis of the plasma shunt consumable electrode arc welding gun and the base metal and the distance between the plasma confinement nozzle and the base metal, wherein the axis of the plasma shunt consumable electrode arc welding gun is vertical to the base metal, and the distance between the plasma confinement nozzle and the base metal is 4-15 mm;

(3) the extension of the welding wire and the distance between the end of the welding wire and the base material are adjusted through a wire feeding mechanism, the extension length of the welding wire is 20mm to 60mm, and the distance between the end of the welding wire and the base material is 2mm to 7 mm;

(4) setting technological parameters: MIG current is between 50 and 600A, bypass plasma arc current is between 0 and 500A, the diameter of a welding wire is 0.8 to 1.6mm, the ionic gas flow is 0.5 to 10.0L/min, the protective gas flow is 5 to 25L/min, the wire feeding speed is 3.0 to 20.0m/min, and the welding speed is 50 to 400 cm/min;

(5) the MIG power supply is turned on, the wire feeding mechanism is started to ignite MIG electric arc, the MIG electric arc ascends in the combustion process, a loop is formed between an annular plasma electrode and a welding wire under the action of the MIG electric arc, the plasma electric arc of a bypass is ignited, the plasma electric arc of the bypass is coupled with the MIG electric arc to form a composite electric arc, the composite electric arc is utilized to weld a base metal, an outer plasma arc is compressed in the welding process, and the MIG electric arc and the welding wire are surrounded by the plasma arc;

(6) in the welding process, a bypass plasma arc is used for shunting, a current sensor detects welding current Im flowing through a base metal, a control system adjusts the size of bypass welding current Ip, and under the condition that the total welding heat quantity is not changed, the control system adjusts the size of the bypass welding current Ip and adjusts the heat input flowing through the base metal, so that the weld forming and welding deformation control are realized.

The invention has the advantages that:

1. because the dry extension of the welding wire is larger, the temperature of the bypass plasma arc is high, the composite electric arc has good preheating function on the workpiece and the welding wire, and the deposition efficiency of the composite electric arc welding can be greatly improved. The plasma nozzle is connected with the cathode of the shunt electric arc, and the burning loss of the nozzle can be greatly reduced, the bearing capacity of the welding gun is improved and the welding process is stabilized only through partial current.

2. Due to the existence of the bypass plasma arc, the stability of the composite arc is enhanced, and little or no spatter is generated in the welding process. The addition of the bypass current enables the arc forming of the main path current to be more stable, greatly promotes the molten drop transition above a molten pool, obtains high welding wire melting efficiency while keeping the low heat input welding of base metal, further reduces the width of a heat affected zone and welding deformation, and improves the welding quality.

3. The bypass plasma arc has the functions of arc stabilization and arc maintenance for the composite arc. The effect of the bypass plasma arc on the molten drop increases the adjustment range of the welding parameters. With matching plasma current parameters, the consumable electrode current regulation range can be multiplied from zero amps up to several hundred amps. Therefore, the welding wires with the same diameter can be used for filling different sections and groove forms.

4. The bypass plasma arc has high current density and plasma flow force, so that external gas can be prevented from entering molten drops, and the plasma arc has a stirring effect on molten pool metal and is beneficial to escape of welding seam gas, so that the defect of pores in the welding seam can be effectively reduced.

5. Because the negative pole of the power supply is connected with the base metal, the oxide film on the surface of the metal can be effectively removed by utilizing the cathode cleaning action of the electric arc. Meanwhile, the electric arc coupling characteristic of the composite electric arc can refine grains in a welding seam area and improve the quality of the welding seam, so that the composite electric arc welding method is particularly suitable for welding nonferrous metals such as aluminum alloy, titanium alloy and the like.

6. The process essentially belongs to the modification of arc welding, has the characteristics of low cost, strong adaptability and the like of the arc welding, can be used for welding positions such as flat welding and other positions (such as vertical welding) according to actual welding requirements, and can be widely applied to the welding process of metal structures such as thin walls, medium and thick walls.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

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, fig. 1 is a schematic diagram of a plasma split consumable electrode arc welding apparatus and a welding method implemented by the apparatus, the welding apparatus mainly comprises a MIG welding power supply 1, a plasma split consumable electrode arc welding torch 2, a wire feeder 5, a split module 8, a control system 14, a current sensor 13, a base metal 12, and the like. The plasma shunting consumable electrode welding gun 2 is a key part of the whole mechanism and mainly comprises an MIG welding contact nozzle 7, an insulating protective porcelain sleeve 4, a water-cooling copper sleeve 3, an annular plasma electrode 9, a plasma restraint nozzle 10, a protective gas hood 11, a filler wire 6 and the like. The MIG welding contact tip 7 is positioned inside the annular plasma electrode 9, the special design can ensure that the MIG electric arc is uniformly surrounded by the bypass plasma electric arc when burning, the outer layer plasma arc has stronger preheating function on welding wires and molten drops, and the welding wire melting efficiency can be greatly improved. Meanwhile, the intervention of the outer plasma arc enables molten drop stress conditions, the stability of the electric arc, the molten drop transition form and the like are changed, the stability of the composite electric arc is enhanced, the molten drop transition is more stable, and the splashing can be effectively reduced in the welding process. During welding, the anode and the cathode of the MIG welding power supply 1 are respectively connected with the welding wire 6 and the workpiece 12, the annular plasma electrode 9 is connected with the water-cooling copper sleeve 3 through threads, and the anode and the cathode of the shunting module 8 are respectively connected with the welding wire 6 and the water-cooling copper sleeve 3. During welding, the MIG welding power supply 1 is turned on, the wire feeding mechanism 5 is started to ignite a MIG electric arc 16, a loop is formed between the annular plasma electrode 9 and the welding wire 6 under the action of the MIG electric arc 16, a bypass plasma electric arc 15 is ignited, and the bypass plasma electric arc 15 is coupled with the MIG electric arc 16 to form a composite electric arc 17. In the welding process, the current sensor 13 is used for detecting the current flowing through the base metal 12, the resistance value of the shunt module 8 is adjusted through the control system 14, the current flowing through the bypass plasma arc 15 and the base metal 12 can be controlled, the welding heat input can be effectively controlled, and the welding quality is improved.

The plasma shunt consumable electrode arc welding method based on the embodiment comprises the following steps:

step 1: before welding, the workpiece 12 is processed according to welding requirements (e.g., cleaning an oxide film on the surface of a base metal, beveling, etc.), and then the workpiece 12 is fastened by a welding tool, and all welding equipment and devices are connected according to the method shown in fig. 1.

Step 2: the angle between the axis of the plasma arc welding gun 2 of the consumable electrode and the workpiece 12 to be welded and the distance between the plasma confinement nozzle 10 and the workpiece 12 are adjusted through the welding tool fixture, the axis of the plasma arc welding gun 2 and the workpiece 12 to be welded are in a vertical state, the distance between the confinement nozzle 10 and the workpiece 12 to be welded is not too far, otherwise, the climbing distance of the MIG arc 16 is not enough, and the plasma arc 15 of the bypass cannot be smoothly ignited, and generally the distance is 4mm to 15 mm.

And step 3: the extent of the wire 6 and the distance of the end of the wire 6 from the workpiece 12 are adjusted by the wire feeder 5. The extension length of the welding wire 6 is generally 20mm to 60mm, the dry extension of the welding wire is large, the composite arc 17 has a good preheating effect on the welding wire 6, and the welding deposition rate can be greatly improved. The end of the welding wire 6 is at a distance of 2mm to 7mm from the workpiece 12.

And 4, step 4: because the method has high welding efficiency, stable welding process and strong current bearing capacity of the water-cooled annular plasma electrode 9, larger welding process parameters can be selected, and the process parameters are generally as follows: the MIG current of the consumable electrode is between 50 and 600A, the bypass plasma current is between 0 and 500A, the diameter of the welding wire is 0.8 to 1.6mm, the ionic gas flow is 0.5 to 10.0L/min, the protective gas flow is 5 to 25L/min, the wire feeding speed is 3.0 to 20.0m/min, the welding speed is 50 to 400cm/min and the like.

And 5: after the MIG welding power supply 1 is turned on, the wire feeding mechanism 5 is started to ignite a MIG electric arc 16, the MIG electric arc 16 ascends in the combustion process, at the moment, a loop is formed between the annular plasma electrode 9 and the welding wire 6 under the action of the MIG electric arc 16 to ignite a bypass plasma electric arc 15, the bypass plasma electric arc 15 is coupled with the MIG electric arc 16 to form a composite electric arc 17, the workpiece 12 is welded by the composite electric arc 17, the outer layer plasma arc 15 is compressed in the welding process, the MIG electric arc 16 and the welding wire 6 are surrounded by the glowing plasma arc 15, the outer layer plasma arc 15 has a strong preheating effect on the welding wire, and the welding deposition rate of the composite electric arc 17 is improved.

Step 6: during welding, the bypass plasma arc 15 is used for shunting. The existence of the bypass plasma arc 15 can change the heat input and the force field distribution acting on the molten drop and the molten pool, greatly stabilize the welding process, reduce the welding spatter and the welding defect and ensure the formation of the welding seam. The current sensor 13 is capable of sensing the welding current Im flowing through the workpiece 12 and the control system 14 is capable of adjusting the magnitude of the bypass welding current Ip. Under the condition that the total welding heat is not changed, the control system 14 adjusts the size of the bypass welding current Ip, so that the heat input flowing through the base metal can be adjusted, and the welding seam forming and the welding deformation can be accurately controlled.

The invention relates to an arc welding device and a welding method for a plasma shunt consumable electrode, which comprises an MIG welding power supply, a plasma shunt consumable electrode welding gun, a wire feeding mechanism, a shunt module, a current sensor, a control system thereof and the like. During welding, the anode and the cathode of an MIG welding power supply are respectively connected with a welding wire and a base metal, the anode and the cathode of a shunting module are respectively connected with the welding wire and an annular plasma electrode, the MIG welding power supply is turned on, a wire feeding mechanism is started to ignite MIG electric arc, and a loop is formed between the annular plasma electrode and the welding wire under the action of the MIG electric arc to ignite bypass plasma electric arc. Thus, one part of the main circuit current flowing through the welding wire flows to the negative electrode of the welding power supply through the base metal, and the other part of the main circuit current flows to the negative electrode of the power supply through the bypass plasma arc under the action of the shunt module. In the welding process, the bypass plasma arc and the MIG arc are coupled with each other to form a composite arc, the bypass arc has a preheating effect on the welding wire, the melting efficiency of the welding wire can be greatly improved, the existence of the bypass arc has arc stabilizing and maintaining effects on the composite arc, the stability of the welding process can be improved, splashing is reduced, the bypass arc has a shunting effect, heat input to a base metal can be reduced, and the welding quality is improved. In the welding process, the current sensor is used for detecting the current flowing through the base metal, and the control system is used for adjusting the shunt module, so that the current flowing through the bypass and the base metal can be controlled, the heat and force distribution acting on the electric arc and the molten pool is reasonably distributed, the welding seam forming can be effectively controlled, and the welding quality can be improved. The method effectively combines the advantages of high plasma arc welding efficiency of the consumable electrode, low heat input of the bypass shunt to the base metal, good welding quality and the like, can greatly improve the welding quality and efficiency of thick plates and thin plates, and reduces the welding deformation of the thin plates.

Claims

1. Plasma reposition of redundant personnel melting electrode arc welding set, characterized by: the plasma split-flow consumable electrode arc welding machine comprises an MIG power supply, a split-flow module, a plasma split-flow consumable electrode arc welding gun, a current sensor and a control system; the plasma shunting consumable electrode arc welding gun comprises a wire feeding mechanism, an MIG welding conductive nozzle, an insulating protective porcelain bushing, an annular plasma electrode, a plasma confinement nozzle and a protective gas shield, wherein a welding wire extends into the MIG welding conductive nozzle through the wire feeding mechanism, the MIG welding conductive nozzle is positioned in the insulating protective porcelain bushing, the annular plasma electrode is connected with a water-cooling copper bushing through threads, the annular plasma electrode and the water-cooling copper bushing are positioned outside the insulating protective porcelain bushing, the plasma confinement nozzle is arranged outside the annular plasma electrode, and the protective gas shield is arranged outside the plasma confinement nozzle; the positive pole of MIG power connects the welding wire, and the work piece is connected to the negative pole of MIG power, and the welding wire is connected to the positive pole of reposition of redundant personnel module, and the water-cooling copper sheathing is connected to the negative pole of reposition of redundant personnel module, and current sensor connects the electric current that detects the parent metal and connects control system, and control system connects and adjusts the resistance of reposition of redundant personnel module.

2. The plasma split-flow consumable electrode arc welding apparatus of claim 1, wherein: the water-cooled copper sleeve is provided with cooling water, an ion gas channel is formed between the water-cooled copper sleeve and the connector of the annular plasma electrode and the insulating protective porcelain sleeve, and a protective gas channel is formed between the plasma confinement nozzle and the protective gas cover.

3. The plasma split-flow consumable electrode arc welding apparatus as set forth in claim 1 or 2, wherein: after the MIG power supply is turned on and the wire feeding mechanism is started, MIG electric arc is generated at the end of the welding wire, a loop is formed between the annular plasma electrode and the welding wire, the ion gas is ignited to form bypass plasma electric arc, and the bypass plasma electric arc is coupled with the MIG electric arc to form composite electric arc.

4. The plasma shunting consumable electrode arc welding method is characterized in that: using the plasma split-flow consumable electrode arc welding apparatus of claim 1: