A welding device and process for controlled distribution of protective flux for gas metal arc welding of dissimilar metals

Abstract

The application discloses a controllable distribution gas protection titanium-steel metal-inert gas welding gun head and a welding process. The application controls the composition of the protection gas at different welding positions by improving the structure of the welding gun head, and performs physical / chemical synergistic metallurgical regulation on the steel-copper-titanium welding process through the active-inert atmosphere, so that a high-quality interface reaction layer on the titanium-copper side and excellent weld forming on the copper-steel side are obtained. The welding gun head comprises a conductive arm, a gas introducer, a flow divider, an insulating sleeve, a baffle, a conductive nozzle and a nozzle. The nozzle is divided into two regions with different area ratios by selecting a ceramic insulating sleeve with two baffles with different angles. Two kinds of different protection gases introduced by the gas holes and the gas introduction holes are introduced into the two regions, the two regions are uniformly protected, especially the two kinds of metals on different sides during the heterogeneous metal welding process, the needs of different protection gases for the metals on different sides are ensured, and the controllable distribution protection effect of the gases is realized.

Description

Technical Field

[0001] This invention relates to the field of dissimilar metal welding technology, particularly to the field of filler wire brazing of dissimilar metals, specifically to a dissimilar metal welding device (welding torch head) with controllable distribution of the consumable electrode and a welding process method. Background Technology

[0002] Titanium alloy and stainless steel connectors can fully utilize the advantages of both metals, meeting the application requirements of high specific strength, strong corrosion resistance, good low-temperature performance, and low specific gravity. They are currently widely used in ship structural components, nuclear power plant waste reprocessing devices, and many other areas. However, due to the differences in the physicochemical properties of titanium alloys and stainless steel, and the formation and aggregation of brittle Ti-Fe intermetallic compounds (IMCs), the joint strength obtained by direct welding is relatively low. It has been found that the highest strength is achieved when the titanium side is a brazed joint and the steel side is a fusion weld joint. Therefore, when using gas metal arc welding (GMAW), efforts are made to obtain a fusion weld interface on the steel side and a brazed interface on the titanium side. The wettability of the weld wire droplets has a significant impact on the joint form and thus on the connection performance, and the composition of the shielding gas can significantly alter the wettability of the droplets. Existing conventional GMAW nozzles can only uniformly deliver one type of welding shielding gas to protect the base materials on both sides. Therefore, under the existing conditions, when pure argon gas is fed in alone, the spread and wettability of the molten droplets on the steel side is poor, resulting in poor formation of the front and back sides of the weld. This easily leads to defects such as undercut, incomplete penetration, and poor back fusion, and the back side of the weld may even lack formation. When mixed shielding gas is fed in alone, the wettability of the molten droplet metal is significantly improved. Under the Marangoni effect, the molten pool flows, the penetration depth increases, and the back side of the joint forms excellently. However, the addition of a small amount of active carbon dioxide gas will cause a relatively obvious oxidation phenomenon on the titanium side, affecting the performance of the welded joint. Although the external formation is acceptable, the strength still does not meet the requirements. Summary of the Invention

[0003] To address the aforementioned technical problems, the objective of this invention is to provide a welding torch head and process method for welding dissimilar metals that require different protective gases and are delivered in a split manner on opposite sides.

[0004] To achieve the above objectives, the technical solution adopted by this invention is as follows: A welding apparatus and method for dissimilar metals with controllable distribution of the consumable electrode, characterized in that, based on the differences in the wettability of different shielding gases to the molten droplets and their protective properties to the base material, thus affecting joint formation, the shielding gas composition at different welding positions is changed by improving the welding torch head structure, thereby improving weld formation. By designing an evacuator and a baffle-insulating sleeve structure inside the nozzle, two different gases are introduced to protect the metal on different sides during the welding process, ensuring the different shielding gas requirements for the metal on different sides are met. This invention discloses a controllable gas distribution shielded titanium-steel consumable electrode welding torch head and process method. The torch head structure includes a conductive arm, a gas vent, a distributor, an insulating sleeve and baffles, a conductive nozzle, and a spray nozzle. The spray nozzle has a circular nozzle opening. By selecting a ceramic insulating sleeve with baffles at different angles on both sides, the nozzle opening is divided into two regions with different area ratios. In the titanium-steel connection, the area ratio of the protected regions is 1:1, i.e., the angle between the two baffles is 180°. Two different shielding gases are introduced through the original vent and the gas vent, passing through the distributor holes of the gas vent and the distributor and the vent groove of the insulating sleeve, and then into the corresponding two regions. This uniformly protects the two regions, especially the two metals on different sides during dissimilar metal welding, ensuring the different shielding gas requirements of the metals on different sides and achieving a controllable gas distribution protection effect. The welding method addresses the issue that the differences in the wettability of molten droplets and the protective properties of different shielding gases affect joint formation. By improving the structure of the welding torch head, the composition of the shielding gas at different welding positions can be altered, thereby improving weld formation and joint performance.

[0005] Preferably, the controllable gas shielded titanium-steel metal arc welding torch head is a CMT welding torch head, and the welding torch head includes a gas siphon, a distributor, an insulating sleeve and baffle, a conductive tip and a nozzle.

[0006] Preferably, the controllable distribution gas-protected titanium-steel metal arc welding torch head is characterized in that the welding torch head is provided with a gas vent and a flow divider, a second gas is introduced through the gas vent to protect the welding process, the gas vent contains a flow divider to divide the introduced gas and make it flow out evenly, and the flow divider divides the gas that passes through the original vent.

[0007] Preferably, the controllable distribution gas-protected titanium-steel metal arc welding torch head is characterized in that the welding torch head is provided with a ceramic insulating sleeve with baffles, the baffles and the insulating sleeve are an integral structure, the two baffles are at a certain angle, and the insulating sleeve has a single-sided venting groove at the position of the two diversion holes, the two venting grooves are respectively located between the two baffles, so that a gas flows only on one side between the baffles, which is the controllable protective gas.

[0008] Preferably, the controllable distribution gas-protected titanium-steel metal arc welding torch head is characterized in that the controllable protective gas is obtained by changing the insulating sleeve with different baffle angles, which can divide the nozzle into two regions with different volume ratios. The two regions are respectively supplied with different protective gases, so that different gases are protected according to a certain area ratio, thereby achieving controllable gas distribution. In the titanium-steel connection, the baffles on both sides are at 180°.

[0009] Preferably, the controllable distribution gas-protected titanium-steel gas metal arc welding torch head is characterized in that it is suitable for gas metal arc welding of dissimilar metals, where different metals on different sides require two different shielding gases to achieve a welded joint with good performance. The two different shielding gases (taking titanium-steel as an example) refer to: pure argon gas is used for protection on the titanium plate side, and a mixed shielding gas is used for protection on the steel plate side.

[0010] Preferably, the controllable distribution gas-protected titanium-steel metal arc welding torch head is characterized in that the mixed protective gas is adjusted in CO2 ratio by a CO2-Ar gas ratio device, the gas ratio device is supplied with a certain amount of high-purity Ar and CO2 respectively, and the CO2 and pure Ar can be ratioed on the gas ratio device by a monitoring panel and an adjustment knob, controlling the CO2 gas content to be 0.5%, 1.0%, 2.0%, 3.0%, 5%, 10%, 15% and 20% respectively.

[0011] Preferably, the controllable gas distribution protective titanium-steel metal arc welding torch head is characterized in that a grooved pad is placed below the fixture, steel plate and titanium plate, and the groove is set on a copper pad with a thickness of 10mm.

[0012] Preferably, the controllable gas-protected titanium-steel metal arc welding torch head is characterized in that a molten weld joint is formed on the steel side and a brazed joint is formed on the titanium side during the welding process.

[0013] According to a second aspect of the present invention, a method for using a controllable gas distribution protected titanium-steel metal arc welding torch head (taking titanium-steel as an example) is provided, comprising the following steps:

[0014] Step 1: Using a CMT welding power source, the ratio of the two shielding gas protection areas is determined using the above invention. In the titanium-steel connection, it is 1:1, i.e., the angle between the two baffles is 180°. A specific insulating sleeve is selected, and the welding gun is assembled. CO2 and Ar are mixed using a gas mixing device to obtain mixed shielding gases containing different proportions of CO2. The CO2 gas contents are 0.5%, 1.0%, 2.0%, 3.0%, 5%, 10%, 15%, and 20%, respectively. The preferred gas content is 3.0%. The active gas is applied to the steel plate side, and high-purity Ar gas is applied to the titanium plate side as the shielding gas. The flow rates of both the mixed shielding gas and the pure Ar gas are 7.5 L / min.

[0015] Step 2: Select copper-based welding wire with a diameter of 1.2mm to join dissimilar metals such as titanium and steel. The welding process parameters are as follows: welding current is 60-80A, preferably 65A, matching welding voltage is 12V, wire feed speed is 2.2m / min, and welding speed is 4mm / s, 6mm / s, 8mm / s, 10mm / s, 12mm / s, 14mm / s, preferably 8mm.

[0016] Step 3: After completing the process parameter settings, first introduce protective gas. After confirming that the gas ratio device monitoring data is correct, mechanically grind the plate and clean it with acetone. Place the titanium plate and steel plate on the grooved copper pad, adjust the mating gap to 0.5mm, and then clamp them.

[0017] Step 4: After clamping, first turn on the protective gas. After confirming that the gas ratio device is correct, use the robot to set the arc starting point and arc ending point, start the welding button, and begin active-inert gas composite welding.

[0018] Step 5: After the active-inert gas composite welding is completed, extinguish the arc, turn off the shielding gas, and then remove the clamps. The welding process is now complete.

[0019] This invention provides a method for using a controllable distribution gas shielded titanium-steel metal arc welding torch head. The welding method employs a novel nozzle design with a concave arc-shaped baffle near the electrical connector on the nozzle's inner side. Two different shielding gases are diverted into the welding torch via a gas screen and a flow divider, protecting the base metal on different sides. This ensures that the base metal on each side requires different shielding gases, further guaranteeing weld formation and joint performance. Specifically, pure Ar is used for protection on the titanium side to prevent oxidation and form a brazed joint, while a mixed shielding gas (CO2 and Ar) is used on the steel side to increase wettability and form a fusion weld joint. Using this novel controllable distribution gas shielded welding method, while preventing oxidation on both sides, the wettability and spread of the molten droplets are increased, the temperature gradient on both sides of the weld is altered, the penetration depth is increased, and the joint formation, especially the back side formation, is improved, resulting in significantly enhanced mechanical properties of the fusion-brazed joint. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this embodiment, the technical solution of the present invention will be further described below with reference to the accompanying drawings. Of course, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings:

[0021] Appendix Figure 1 This is a structural diagram of the welding torch head described in the welding method of the present invention;

[0022] Appendix Figure 2 These are three views of the overall structure of the welding torch head described in the welding method of the present invention.

[0023] Appendix Figure 3 The welding torch head described in the welding method of the present invention is shown in sectional views AA and BB.

[0024] The labels in the attached diagrams are as follows: 1. Conductive arm; 2. Air duct; 21. Air duct hole; 3. Diverter; 4. Insulating sleeve; 41. Ceramic baffle; 5. Conductive nozzle; 51. Welding wire hole; 6. Nozzle; 01. Diverter hole; 02. Ventilation groove; 03. Thread. Detailed Implementation

[0025] Appendix Figure 1 , 2 3. The welding torch head of the gas metal arc welding method of the present invention includes: a conductive arm 1, a gas eliminator 2, and a flow divider 3, all made of brass; an insulating sleeve 4 and a ceramic baffle 41 are an integral structure made of ceramic; a conductive nozzle 5 and a nozzle 6 are made of copper with a high melting point and that is not easily deformed by heat; by changing the insulating sleeve to present different angles with the baffle, the nozzle can be divided into two regions with different volume ratios, and different shielding gases are passed through the two regions respectively, so that different gases are protected according to a certain area ratio, and the gas distribution can be controlled; the first gas (pure Ar) passes through the inside of the welding torch, through the conductive arm and the gas eliminator, and is divided in the flow divider. The gas is diverted through hole 01 and enters one of the two areas separated by ceramic baffles on both sides after passing through the vent groove 02 on the insulating sleeve. The second gas (mixed protective gas) enters the vent through vent 21, and is diverted through the diversion hole 01 and the vent groove 02 on the insulating sleeve to enter the other area separated by ceramic baffles on both sides. After passing through the vent, this gas directly enters the nozzle, completely isolated from the first gas, effectively avoiding premature mixing of the protective gas and weakening the protection effect on dissimilar metals on both sides, thus ensuring welding quality. The conductive arm 1 is connected and fixed to the vent 2, the vent 2 to the diverter 3, the diverter 3 to the insulating sleeve 4, and the insulating sleeve 4 to the conductive nozzle by threads 03.

[0026] The invention of this controlled gas distribution protection device and method for titanium-steel welding lies in the addition of a gas evacuator and an improved insulating sleeve structure to the existing welding torch. This allows for the introduction of a second gas stream while completely isolating it from the first, with each gas stream residing in its own isolated protective gas chamber until it reaches the weld and base material. Furthermore, by changing the baffle to create insulating sleeves at different angles, the nozzle can be divided into two regions with different volume ratios. Each region is supplied with a different protective gas, ensuring that different gases provide protection according to specific area proportions, thus meeting the different protective gas requirements for the different metals on each side. This achieves controlled gas distribution protection. Through active-inert atmosphere synergistic metallurgical control of the steel-copper-titanium welding process, a high-quality interface reaction layer on the titanium-copper side and excellent weld formation on the copper-steel side are obtained.

[0027] In this embodiment, a cold metal transfer (CMT) welding robot is used with a controlled metal electrode distribution (MED) shielded welding method to perform butt welding of dissimilar metals (TC4 titanium alloy plate and 304L stainless steel plate) without beveling. The selected shielding gas on the titanium side is pure argon, and the shielding gas on the steel side is a mixed shielding gas; the flow rate of both shielding gases is 7.5 L / min. The selected welding wires are CuAl7, CuSi3, and pure Cu; preferably, in this example, pure CuSi3 filler wire is used.

[0028] Furthermore, both the titanium plate and the stainless steel plate are 1mm thick, and the welding gap is 0.5mm.

[0029] Furthermore, the diameter of the welding wire is 1.2 mm.

[0030] Furthermore, the welding current can be selected as 60A-70A, and in this example, the welding current is preferably 65A; the welding voltage can be selected as 11.5V-12.4V, and in this example, the welding voltage is preferably 12V.

[0031] Furthermore, the welding speed can be selected from 4 mm / s to 14 mm / s, and in this example, the welding speed is preferably 8 mm / s.

[0032] Furthermore, the wire feeding speed can be selected as 2.0-2.5 m / min, and in this example, the preferred wire feeding speed is 2.2 m / min.

[0033] Furthermore, in this example, preferably, the two side baffles are at 180°, with a zone protection ratio of 1:1; the mixed protective gas on the steel side is selected as 3.0% CO2 and 97.0% Ar. The flow rates of both pure argon and the mixed protective gas are selected as 7.5 L / min.

[0034] The specific welding steps of this controlled distribution of consumable electrode shielding welding method are as follows:

[0035] a. Before welding, the plate is mechanically ground and wiped with acetone to remove the oxide film.

[0036] b. Assemble the titanium plate and stainless steel plate above the forming groove using a welding clamping device.

[0037] c. Adjust the position of the protective gas baffle; open the two protective gas valves respectively, adjust the flow rate, and check whether the base material assembly on the corresponding side of the protective gas is matched.

[0038] d. Use the robot to set the arc starting point and arc ending point, and begin welding.

[0039] f. Close the welding shielding gas valve.

[0040] The above embodiments are only for illustrating the concept and features of the present invention, and are intended to enable those skilled in the art to understand the solution and combine it with more embodiments. They should not be used to limit the scope of protection of the present invention. All equivalent modifications or alterations made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A controllable gas-shielded titanium-steel metal arc welding torch head, characterized in that, Based on the fact that different shielding gases have different wettability to molten droplets and different protective properties to the base metal, thus affecting the joint formation, the shielding gas composition at different welding positions can be changed by improving the structure of the welding torch head, thereby improving the weld formation. The welding torch head structure includes a conductive arm, a gas siphon, a flow divider, an insulating sleeve and ceramic baffle, a conductive nozzle, and a nozzle. The nozzle is provided with a nozzle orifice, which is circular; by using an insulating sleeve with ceramic baffles on both sides presenting different angles, the nozzle orifice is divided into two areas with different area ratios. The conductive arm is fixed to the air eliminator, the air eliminator to the diverter, the diverter to the insulating sleeve, and the insulating sleeve to the conductive nozzle by threaded connections. The air expirator is provided with an air expiratory port; The distributor is provided with a diversion hole; The insulating sleeve and the ceramic baffle are an integral structure, with the ceramic baffle fixed inside the insulating sleeve. The insulating sleeve has a ventilation groove corresponding to the position of the diversion hole. The first protective gas passes through the inside of the welding torch, through the conductive arm and the gas evacuator, and is then split through the splitting hole in the splitter. It then passes through the venting groove on the insulating sleeve and enters one of the two areas separated by the ceramic baffle. The second protective gas enters the vent through the vent hole, and is then diverted through the diversion hole of the distributor and the vent groove on the insulating sleeve into another area separated by the ceramic baffle.

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