A hot-formed steel arc welding apparatus and method based on forced cooling

Abstract

The present application belongs to the technical field of hot forming steel electric arc welding, and particularly relates to a hot forming steel electric arc welding device based on forced cooling, which comprises a box body, a welding gun and a cooling system, the cooling system comprises a water-cooled gun support and a water-cooled gun, the water-cooled gun support is slidingly installed in the box body, the water-cooled gun is installed on the water-cooled gun support, and the welding head of the welding gun is in front and the outlet end of the water-cooled gun is in back along the welding direction; the water-cooled gun comprises a water-cooled channel and a high-pressure protective gas channel, when welding is performed, the water-cooled gun support drives the water-cooled gun to move synchronously with the welding gun, at the same time, the water-cooled channel is connected with cooling water to cool the welding part, and the protective gas in the high-pressure protective gas channel can form a gas curtain to block the cooling water, so that the water-cooled channel of the water-cooled gun is in a closed state along the welding direction. The present application can not only reduce the heat input of the heat affected zone and weaken the softening degree of the tempering zone, but also maintain the original welding production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot-formed steel arc welding, and in particular relates to a hot-formed steel arc welding device and method based on forced cooling. Background Art

[0002] Vehicle lightweighting technology is currently a hot topic in the field of energy conservation and emission reduction, and the requirements for lightweighting are becoming increasingly stringent. Research shows that a 10% reduction in vehicle mass can improve fuel efficiency by 7%. Currently, high-strength steel, especially hot-formed steel, has great potential for application in the automotive field, especially in commercial vehicle lightweighting. It can be widely used in body, frame, compartment, and leaf springs.

[0003] Hot-formed steel is primarily produced using a hot stamping process. The main process involves heating the steel to increase its ductility and reduce metal flow resistance, making the stamping process easier. The initially formed parts are then quenched in a mold to produce higher-strength parts. Compared to traditional steel production, the hot forming heating process heats the material to a high temperature, significantly increasing its plasticity and reducing its yield strength. After holding the material at this temperature, it is transferred to a mold equipped with a cooling system for rapid forming. Experimental results indicate that softening of the tempering zone occurs during the welding of hot-formed steel. This is due to the loss of the strengthening effect inherent in the original TMCP steel during the welding process. The research results show that the softening zone of the welded joint mainly occurs between 350 ℃ and Ac3 temperature. The main reason is that carbides precipitate in the martensite in the tempering zone to form tempered martensite, while the dislocation density in the ferrite decreases. At the critical temperature, the original martensite in the base material transforms into austenite, and then transforms into ferrite, bainite and martensite during the cooling process. The retained austenite phase causes the volume of the softening phase to increase, and the welded joint softens.

[0004] Existing studies have found that reducing the heat input of welding can effectively improve the softening degree of the tempering zone of hot-formed steel. However, reducing the heat input of welding will not only affect the welding quality, but also reduce the welding production efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a hot-formed steel arc welding device and method based on forced cooling in response to the shortcomings of the existing technology. The present invention can not only reduce the heat input in the heat-affected zone and weaken the softening degree in the tempering zone, but also maintain the original welding production efficiency.

[0006] This solution is achieved through the following technical measures: a hot-formed steel arc welding device based on forced cooling, which includes a box, a welding gun and a cooling system.

[0007] The cooling system includes a water-cooling gun bracket and a water-cooling gun, wherein the water-cooling gun bracket is slidably mounted in the box body, and the water-cooling gun is mounted on the water-cooling gun bracket, and along the welding direction, the welding head of the welding gun is in front and the outlet end of the water-cooling gun is in the rear;

[0008] The water-cooling gun includes a water-cooling channel and a high-pressure shielding gas channel. When welding is in progress, the water-cooling gun bracket drives the water-cooling gun to move synchronously with the welding gun. At the same time, cooling water is introduced into the water-cooling channel to cool the weldment. The shielding gas in the high-pressure shielding gas channel can form a layer of air curtain to block the cooling water, so that the water-cooling channel of the water-cooling gun is in a closed state in the welding direction.

[0009] Preferably, the water cooling channel is provided along the axial direction of the water cooling gun, and the high-pressure protective gas channel passes through the side wall of the water cooling gun to the water cooling channel and then bends upward to form an L-shaped channel structure.

[0010] Preferably, the water-cooling channel or a section of the water-cooling channel and the high-pressure shielding gas channel near the outlet end are both arranged as trumpet-shaped reducing sections, and the cross-section of the outlet end of the water-cooling channel is crescent-shaped, and the cross-section of the outlet end of the high-pressure shielding gas channel is circular; along the welding direction, the front end of the outlet end of the water-cooling channel is located at the rear side of the front end of the outlet end of the high-pressure shielding gas channel.

[0011] Preferably, the water-cooling gun is a cylindrical structure, and the angle between the axis of the water-cooling gun and the plumb line is 30°-45°.

[0012] Preferably, a distance is left between the outlet end of the water-cooling gun and the lower surface of the sample to be welded.

[0013] Preferably, a partition is fixedly connected to the box body, and the partition separates the inner cavity of the box body into a welding area at the top and a cooling area at the bottom, so that the welding area and the cooling area are isolated, and the sample to be welded is located in the welding area and placed on the partition.

[0014] Preferably, a guide rail is fixedly connected in the box body, and the water-cooling gun bracket is slidably connected to the guide rail.

[0015] Preferably, a water-cooling gun mounting hole is provided on the water-cooling gun bracket, and a locking bolt is threadedly connected to the water-cooling gun bracket, and the end of the locking bolt can be pressed against the side wall of the water-cooling gun to fix the water-cooling gun;

[0016] A water leakage plate is fixedly connected to the inner cavity of the box body, and the water leakage plate is located above the bottom of the inner cavity of the box body and below the guide rail.

[0017] The present invention also provides a hot-formed steel arc welding method based on forced cooling using the hot-formed steel arc welding device based on forced cooling, which comprises the following steps:

[0018] S1: Grind and clean the sample to be welded to remove impurities and oxide layer on the surface;

[0019] S2: Clamp the sample to be welded in the welding position. The welding joint is a butt weld joint. Connect the welding gun to the welding machine, cooling water and shielding gas. Set the welding parameters to ensure normal welding.

[0020] S3: Fix the water-cooling gun bracket to the guide rail, then fix the water-cooling gun to the water-cooling gun bracket and adjust the height. Connect the water-cooling gun to the cooling water and shielding gas. Enter the water-cooling gun bracket sliding speed that is the same as the welding speed in the CNC system to ensure that the water-cooling gun can be cooled in real time during the welding process.

[0021] S4: Select the water pressure and air pressure of the water-cooling gun. The water pressure range is 0.03-0.08MPa, so that the cooling water can fully contact the lower surface of the sample to be welded. The air pressure range is 0.07-0.1MPa, and the air pressure must be higher than the water pressure and remain stable.

[0022] S5: Before welding begins, first introduce the shielding gas into the water-cooling gun, and then introduce the cooling water to ensure the isolation effect of the gas and prevent the cooling water from entering the area to be welded. After the water pressure and air pressure are stable, start welding. After welding starts, the water-cooling gun will move with the welding gun and perform real-time cooling during the welding process.

[0023] Preferably, in step S4, the air pressure is 0.02-0.04 MPa higher than the water pressure.

[0024] Beneficial effects of the present invention: The present invention allows for real-time cooling while welding by having the water-cooling gun move synchronously with the welding gun. This provides a better cooling effect than the prior art method of cooling after welding. The bell-shaped reducing section of the cooling water channel is designed to allow the cooling water to be discharged smoothly outward without entering the weld. The protective gas within the cooling water protects the welding environment while preventing the cooling water from entering the weld, thereby ensuring welding quality. While maintaining the original welding production efficiency, the present invention reduces the softening degree of the tempering zone. This shows that, compared with the prior art, the present invention has outstanding substantive features and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the internal structure of the hot-formed steel arc welding device based on forced cooling in the present invention.

[0026] Figure 2 This is a schematic diagram of the main structure of the cooling system in the present invention.

[0027] Figure 3 It is a side structural schematic diagram of the cooling system in the present invention.

[0028] Figure 4 This is a schematic diagram of the three-dimensional structure of the water-cooling gun.

[0029] Figure 5 This is a schematic diagram of the cross-sectional structure of the water-cooling gun.

[0030] In the figure: 1- welding gun; 2- sample to be welded; 3- partition; 4- guide rail; 5- leakage plate; 6- water-cooling gun; 7- water-cooling gun bracket; 8- box; 9- weld; 10- heat-affected zone; 11- cooling water; 12- shielding gas; 13- reducing section; 14- water-cooling channel; 15- high-pressure shielding gas channel. DETAILED DESCRIPTION

[0031] In order to clearly illustrate the technical features of this solution, the solution is described below through specific implementation methods and in conjunction with the accompanying drawings.

[0032] A hot-formed steel arc welding device based on forced cooling includes a box body 8, a welding gun 1 and a cooling system. A partition 3 is fixedly connected to the box body 8. The partition 3 divides the inner cavity of the box body 8 into a welding area at the top and a cooling area at the bottom, isolating the welding area and the cooling area to prevent the welding environment from being too humid and affecting the welding quality. The sample 2 to be welded is located in the welding area and placed on the partition 3. The separation of the welding area and the cooling area can ensure a dry atmosphere during welding to ensure welding quality.

[0033] The cooling system includes a water-cooling gun bracket 7 and a water-cooling gun 6. The water-cooling gun bracket 7 is slidably mounted within a housing 8. Specifically, a guide rail 4 is fixedly connected to the housing 8. The water-cooling gun bracket 7 is slidably connected to the guide rail 4 to ensure that during welding, the numerical control system can control the water-cooling gun bracket 7 to drive the water-cooling gun 6 to move synchronously with the welding gun 1, thereby achieving real-time cooling of the heat-affected zone 10. The water-cooling gun 6 is mounted on the water-cooling gun bracket 7, with the welding head of the welding gun 1 in front and the outlet end of the water-cooling gun 6 in the rear along the welding direction. The water-cooling gun bracket 7 has a water-cooling gun mounting hole, and a locking bolt is threadedly connected to the water-cooling gun bracket 7. The end of the locking bolt can be tightened against the side wall of the water-cooling gun 6 to fix the water-cooling gun 6. This structural form not only ensures that the water-cooling gun 6 is firmly fixed, but also allows for convenient height adjustment of the water-cooling gun 6. The height of the water-cooling gun 6 can be adjusted by loosening the locking bolt and then tightening the locking bolt after adjustment. The structure is simple and easy to adjust.

[0034] The water cooling gun 6 is cylindrical in structure, and the axis of the water cooling gun 6 forms an angle of 30°-45° with the vertical line. A gap is left between the outlet end of the water cooling gun 6 and the lower surface of the sample 2 to ensure that the cooling water 11 can be discharged normally.

[0035] The water cooling gun 6 comprises a water cooling channel 14 and a high-pressure protective gas channel 15, and the protective gas 12 in the high-pressure protective gas channel 15 has a certain pressure, which can ensure that the cooling water 11 cannot enter the molten pool, so as to ensure the welding quality. The water cooling channel 14 is arranged in the axial direction of the water cooling gun 6, and the high-pressure protective gas channel 15 is arranged from the side wall of the water cooling gun 6 to the water cooling channel 14 and then is bent upwards to form an L-shaped channel structure. The water cooling channel 14 or the water cooling channel 14 and the high-pressure protective gas channel 15 are arranged as a variable diameter section 13 in the form of a horn mouth near the outlet end, the outlet end of the water cooling channel 14 is in the form of a crescent, and the outlet end of the high-pressure protective gas channel 15 is in the form of a circle. In the welding direction, the front end of the outlet end of the water cooling channel 14 is located at the rear side of the front end of the outlet end of the high-pressure protective gas channel 15, so that the gas curtain formed by the high-pressure protective gas 12 can completely block the cooling water 11, and the cooling water 11 is prevented from entering the welding molten pool or the area to be welded.

[0036] The cooling water 11 in the water cooling channel 14 of the water cooling gun 6 is used to cool the sample 2 to be welded, the horn mouth-shaped variable diameter section 13 of the outlet end of the water cooling channel 14 in the form of a crescent can reduce the probability of the cooling water 11 entering the weld 9, and can increase the cooling area, the high-pressure protective gas 12 in the water cooling channel 14 can form a gas curtain to avoid the cooling water 11 from entering the weld 9 and affecting the welding quality, and the axis of the water cooling gun 6 and the plumb line form an angle of 30°-45°, so that the water flow in the oblique direction of the welded area is not easy to enter or be blown into the welding molten pool or the area to be welded by the protective gas, and the dry welding environment is further ensured.

[0037] When the welding is performed, the water cooling gun support 7 drives the water cooling gun 6 to move synchronously along the welding direction on the guide rail 4, and the sliding speed of the water cooling gun support 7 can be precisely adjusted under the control of the numerical control system, and the cooling water 11 in the water cooling channel 14 is used to cool the welding piece, and the protective gas 12 in the high-pressure protective gas channel 15 can form a gas curtain to block the cooling water 11, so that the water cooling channel 14 of the water cooling gun 6 is in a closed state in the welding direction, and the cooling water 11 is prevented from entering the welding molten pool or wetting the area to be welded to affect the welding quality.

[0038] The inner cavity of the box body 8 is fixedly connected with a water leakage plate 5, and the water leakage plate 5 is located above the bottom of the inner cavity of the box body 8 and below the guide rail 4. The cooling water 11 is filtered through the water leakage plate 5, and the filtered cooling water 11 can be recycled.

[0039] The application also provides a forced cooling based hot-formed steel electric arc welding method using the forced cooling based hot-formed steel electric arc welding device.

[0040] S1: Grinding and cleaning the sample 2 to be welded to remove impurities and oxide layers on the surface, wherein the material of the sample 2 to be welded is hot-formed steel;

[0041] S2: Clamp the sample 2 to be welded in the welding position. The welding joint is a butt weld joint. The welding method is arc welding. Connect the welding gun 1 to the welding machine, cooling water and shielding gas. Set the welding parameters to ensure that the welding is carried out normally.

[0042] S3: Fix the water-cooling gun bracket 7 to the guide rail 4, then fix the water-cooling gun 6 to the water-cooling gun bracket 7 and adjust the height. Connect the cooling water 11 and the shielding gas 12 to the water-cooling gun 6. Input the sliding speed of the water-cooling gun bracket 7, which is the same as the welding speed, into the numerical control system to ensure that the water-cooling gun 6 can be cooled in real time during the welding process.

[0043] S4: Select the water pressure and air pressure of the water-cooling gun 6. The water pressure range is 0.03-0.08 MPa so that the cooling water 11 can fully contact the lower surface of the sample 2 to be welded. The air pressure range is 0.07-0.1 MPa. The air pressure should be higher than the water pressure and remain stable. Preferably, the air pressure is 0.02-0.04 MPa higher than the water pressure. The shielding gas 12 can ensure that the cooling water 11 does not enter the molten pool, ensuring the welding quality.

[0044] S5: Before welding begins, the shielding gas 12 is introduced into the water-cooling gun 6, and then the cooling water 11 is introduced to ensure the isolation effect of the gas so that the cooling water 11 does not enter the area to be welded. Welding can be started after the water pressure and air pressure are stable. After welding starts, the water-cooling gun 6 will move with the welding gun 1 and perform real-time cooling during the welding process.

[0045] The present invention adds a water-cooling gun 6 to the back of the specimen 2 to be welded, which moves with the welding gun 1 during welding. The welding gun 1 and the water-cooling gun 6 are respectively positioned on the front and back of the specimen 2 to be welded, and aligned with the weld seam 9 of the specimen 2 to be welded. During welding, the water-cooling gun 6 moves synchronously with the welding gun 1. Cooling water 11 and shielding gas 12 are simultaneously introduced into the water-cooling gun 6, forcibly cooling the heat-affected zone 10 during welding. Due to the water curtain protection created by the shielding gas 12, the cooling water 11 does not enter the weld seam 9 and affect the weld quality. This forced cooling significantly reduces the heat input to the heat-affected zone 10, weakening the softening of the tempering zone and improving the strength of the weld joint.

[0046] Technical features not described in the present invention can be implemented by existing technologies and will not be described in detail here. The present invention is not limited to the above-mentioned specific embodiments. Changes, modifications, additions or substitutions made by ordinary technicians in this field within the scope of the essence of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A hot-formed steel arc welding device based on forced cooling, comprising a box, a welding gun and a cooling system, characterized in that: The cooling system includes a water-cooling gun bracket and a water-cooling gun, wherein the water-cooling gun bracket is slidably mounted in the box body, and the water-cooling gun is mounted on the water-cooling gun bracket, and along the welding direction, the welding head of the welding gun is in front and the outlet end of the water-cooling gun is in the rear; The water-cooling gun includes a water-cooling channel and a high-pressure shielding gas channel. When welding is in progress, the water-cooling gun bracket drives the water-cooling gun to move synchronously with the welding gun. At the same time, cooling water is introduced into the water-cooling channel to cool the weldment. The shielding gas in the high-pressure shielding gas channel forms a layer of air curtain to block the cooling water, so that the water-cooling channel of the water-cooling gun is in a closed state in the welding direction. The water cooling channel or a section of the water cooling channel and the high-pressure shielding gas channel near the outlet end is configured as a trumpet-shaped diameter reducing section, and the outlet end cross-section of the water cooling channel is crescent-shaped, and the outlet end cross-section of the high-pressure shielding gas channel is circular; along the welding direction, the front end of the outlet end of the water cooling channel is located behind the front end of the outlet end of the high-pressure shielding gas channel; A partition is fixedly connected to the box body, which divides the inner cavity of the box into a welding area at the top and a cooling area at the bottom, so that the welding area and the cooling area are isolated. The sample to be welded is located in the welding area and is placed on the partition.

2. The hot-formed steel arc welding device based on forced cooling according to claim 1, characterized in that: The water cooling channel is arranged to penetrate along the axial direction of the water cooling gun, and the high-pressure protective gas channel penetrates from the side wall of the water cooling gun to the water cooling channel and then bends upward to form an L-shaped channel structure.

3. The hot-formed steel arc welding device based on forced cooling according to claim 1 or 2, characterized in that: The water-cooling gun is a cylindrical structure, and the axis of the water-cooling gun forms an angle of 30°-45° with the plumb line.

4. The hot-formed steel arc welding device based on forced cooling according to claim 3, characterized in that: A distance is left between the outlet end of the water-cooling gun and the lower surface of the sample to be welded.

5. The hot-formed steel arc welding device based on forced cooling according to claim 4, characterized in that: A guide rail is fixedly connected inside the box, and the water-cooling gun bracket is slidably connected to the guide rail.

6. The hot-formed steel arc welding device based on forced cooling according to claim 5, characterized in that: The water-cooling gun bracket is provided with a water-cooling gun mounting hole, and a locking bolt is threadedly connected to the water-cooling gun bracket, and the end of the locking bolt is pressed against the side wall of the water-cooling gun to fix the water-cooling gun; A water leakage plate is fixedly connected to the inner cavity of the box body, and the water leakage plate is located above the bottom of the inner cavity of the box body and below the guide rail.

7. A method for hot-formed steel arc welding based on forced cooling using the hot-formed steel arc welding device based on forced cooling according to any one of claims 1 to 6, characterized in that: It includes the following steps: S1: Grind and clean the sample to be welded to remove impurities and oxide layer on the surface; S2: Clamp the sample to be welded in the welding position. The welding joint is a butt weld joint. Connect the welding gun to the welding machine, cooling water and shielding gas. Set the welding parameters to ensure normal welding. S3: Fix the water-cooling gun bracket to the guide rail, then fix the water-cooling gun to the water-cooling gun bracket and adjust the height. Connect the water-cooling gun to the cooling water and shielding gas. Enter the sliding speed of the water-cooling gun bracket that is the same as the welding speed in the CNC system to ensure that the water-cooling gun is cooled in real time during the welding process. S4: Select the water pressure and air pressure of the water-cooling gun. The water pressure range is 0.03-0.08MPa, so that the cooling water can fully contact the lower surface of the sample to be welded. The air pressure range is 0.07-0.1MPa, and the air pressure must be higher than the water pressure and remain stable. S5: Before welding begins, first introduce the shielding gas into the water-cooling gun, and then introduce the cooling water to ensure the isolation effect of the gas and prevent the cooling water from entering the area to be welded. After the water pressure and air pressure are stable, start welding. After welding starts, the water-cooling gun will move with the welding gun and perform real-time cooling during the welding process.

8. The hot-formed steel arc welding method based on forced cooling according to claim 7, characterized in that: In step S4, the air pressure is 0.02-0.04 MPa higher than the water pressure.

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