Hot forming steel electric arc welding device and method based on forced cooling

Abstract

The invention 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-cooling gun support and a water-cooling gun, the water-cooling gun support is slidably mounted in the box body, the water-cooling gun is mounted on the water-cooling gun support, and the water-cooling gun is mounted on the water-cooling gun support. In the welding direction, the welding head of the welding gun is arranged in front, and the outlet end of the water cooling gun is arranged behind; the water-cooling gun comprises a water-cooling channel and a high-pressure protective gas channel, when welding is carried out, the water-cooling gun support drives the water-cooling gun to synchronously move along with the welding gun, meanwhile, cooling water is introduced into the water-cooling channel to cool a weldment, protective gas in the high-pressure protective gas channel can form a layer of gas curtain to block the cooling water, and the cooling water is cooled by the high-pressure protective gas channel. And a water cooling channel of the water cooling gun is in a closed state in the welding direction. Heat input of a heat affected zone can be reduced, the softening degree of a tempering zone is weakened, and the original welding production efficiency can be kept.

Description

Technical Field

[0001] The 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] Automobile lightweight technology is currently a hot topic in the field of automobile energy conservation and emission reduction, and the requirements for automobile lightweighting are becoming increasingly stringent. Studies have shown that a 10% reduction in vehicle mass can increase fuel efficiency by 7%. At present, high-strength steel, especially hot-formed steel, has great application potential in the automotive field, especially in the field of commercial vehicle lightweighting. It can be widely used in body, frame, compartment and leaf springs, etc.

[0003] Hot-formed steel is mainly produced by hot stamping. The main process is to increase the ductility of the steel by heating it, reduce the metal flow resistance, and make the stamping process easier. Then the initially formed parts are quenched in the mold to obtain parts with higher strength. Compared with the production of traditional steel, during the hot forming heating process, the material is heated to a high temperature state, the plasticity is significantly increased, and the yield strength is significantly reduced. After insulation, it is transferred to a mold with a cooling system for rapid forming. From the experimental phenomenon, it can be found that the tempering zone softening phenomenon will occur in the welding of hot-formed steel. This is caused by the disappearance of the strengthening effect in the original TMCP steel during the welding process. The research results show that the softening zone of the welded joint mainly occurs at a temperature between 350 ℃ and Ac3 temperature. The main reason is that carbides precipitate in the martensite in the tempering zone to form tempered martensite, and the dislocation density in the ferrite decreases. At the critical temperature, the original martensite in the base material is transformed into austenite, and then transformed into ferrite, bainite and martensite during the cooling process. The residual 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 view of the shortcomings of the prior art. The present invention can reduce the heat input of the heat-affected zone and weaken the softening degree of the tempering zone, and can 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. The cooling system comprises 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 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.

[0007] Preferably, 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.

[0008] 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 a trumpet-shaped reducing section, 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 in the water-cooling channel is located at the rear side of the front end of the outlet end in the high-pressure shielding gas channel.

[0009] Preferably, 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.

[0010] Preferably, a distance is left between the outlet end of the water-cooling gun and the lower surface of the sample to be welded.

[0011] Preferably, a partition is fixedly connected in the box body, and the partition divides the inner cavity of the box body into a welding area at an upper position and a cooling area at a lower position, 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.

[0012] Preferably, a guide rail is fixedly connected in the box body, and the water-cooling gun bracket is slidably connected to the guide rail.

[0013] 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; A water leakage plate is fixedly connected in 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.

[0014] 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: 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 at the welding position. The welding joint is a butt welding joint. Connect the welding gun to the welding machine, cooling water and protective gas. Set the welding parameters to ensure that the welding is carried out normally. 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 cooling water and protective gas to the water-cooling gun. Input 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 can be 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 should be higher than the water pressure and remain stable. S5: Before welding, first introduce the protective gas into the water-cooling gun, and then introduce the cooling water to ensure the isolation effect of the gas, so that the cooling water will not enter 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.

[0015] Preferably, in step S4, the air pressure is 0.02-0.04 MPa higher than the water pressure.

[0016] Beneficial effects of the present invention: The present invention can perform real-time cooling while welding by having the water-cooling gun move synchronously with the welding gun. The cooling effect is better than the cooling after welding in the prior art. The design of the bell-shaped reducing section of the cooling water channel can allow the cooling water to be discharged smoothly to the outside without entering the weld. The protective gas inside the cooling water can protect the welding environment while preventing the cooling water from entering the weld, thereby ensuring the welding quality. The present invention reduces the softening degree of the tempering zone while maintaining the original welding production efficiency. It can be seen that compared with the prior art, the present invention has outstanding substantive characteristics and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the internal structure of the hot-formed steel arc welding device based on forced cooling in the present invention.

[0018] Figure 2 It is a schematic diagram of the main structure of the cooling system in the present invention.

[0019] Figure 3 It is a side structural schematic diagram of the cooling system in the present invention.

[0020] Figure 4 This is a schematic diagram of the three-dimensional structure of the water-cooling gun.

[0021] Figure 5 It is a schematic diagram of the cross-sectional structure of the water-cooling gun.

[0022] 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

[0023] In order to clearly illustrate the technical features of this solution, this solution is described below through specific implementation methods and in conjunction with the accompanying drawings.

[0024] A hot-formed steel arc welding device based on forced cooling, comprising a box body 8, a welding gun 1 and a cooling system. A partition 3 is fixedly connected to the box body 8, and the partition 3 divides the inner cavity of the box body 8 into a welding area at an upper position and a cooling area at a lower position, so that the welding area and the cooling area are isolated to avoid the welding environment being too humid and affecting the welding quality. The sample 2 to be welded is located in the welding area and is placed on the partition 3. The separation of the welding area and the cooling area can ensure a dry atmosphere during welding to ensure the welding quality.

[0025] 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 in a box body 8. Specifically, a guide rail 4 is fixedly connected in the box body 8. The water-cooling gun bracket 7 is slidably connected to the guide rail 4 to ensure that 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 during welding, so as to achieve real-time cooling of the heat-affected zone 10. The water-cooling gun 6 is mounted on the water-cooling gun bracket 7, and along the welding direction, the welding head of the welding gun 1 is in front and the outlet end of the water-cooling gun 6 is in the back; a water-cooling gun mounting hole is provided on the water-cooling gun bracket 7, and a locking bolt is threadedly connected on the water-cooling gun bracket 7. The end of the locking bolt can be pressed against the side wall of the water-cooling gun 6 to fix the water-cooling gun 6. This structural form can not only achieve the firm fixation of the water-cooling gun 6, but also conveniently adjust the height of the water-cooling gun 6. The height of the water-cooling gun 6 can be adjusted by loosening the locking bolt, and the locking bolt can be tightened after the adjustment is in place. The structure is simple and easy to adjust.

[0026] The water cooling gun 6 is a cylindrical structure, and the axis of the water cooling gun 6 forms an angle of 30°-45° with the plumb line. There is a gap between the outlet end of the water cooling gun 6 and the lower surface of the sample 2 to be welded, so as to ensure that the cooling water 11 can be discharged normally.

[0027] The water-cooling gun 6 includes a water-cooling channel 14 and a high-pressure shielding gas channel 15. The shielding gas 12 in the high-pressure shielding gas channel 15 has a certain pressure, which can ensure that the cooling water 11 will not enter the molten pool to ensure the welding quality. The water-cooling channel 14 is arranged to penetrate along the axial direction of the water-cooling gun 6. The high-pressure shielding gas channel 15 penetrates the side wall of the water-cooling gun 6 to the water-cooling channel 14 and then bends upward to form an L-shaped channel structure. The water-cooling channel 14 or a section of the water-cooling channel 14 and the high-pressure shielding gas channel 15 near the outlet end are all arranged as a bell-shaped reducing section 13, and the cross section of the outlet end of the water-cooling channel 14 is crescent-shaped, and the cross section of the outlet end of the high-pressure shielding gas channel 15 is circular; along 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 shielding gas channel 15 to ensure that the air curtain formed by the high-pressure shielding gas can completely block the cooling water 11 and prevent the cooling water 11 from entering the welding molten pool or the area to be welded.

[0028] The water-cooling channel 14 in the water-cooling gun 6 passes cooling water 11 to cool the sample 2 to be welded. The design of the trumpet-shaped reducing section 13 in the water-cooling channel 14 with a crescent-shaped outlet can reduce the probability of the cooling water 11 entering the weld 9 and increase the cooling area. The high-pressure shielding gas 12 in the water-cooling channel 14 can form a layer of air curtain to prevent the cooling water 11 from entering the weld 9 and affecting the welding quality. At the same time, the axis of the water-cooling gun 6 is at an angle of 30°-45° to the plumb line, and the water flow in the oblique post-weld area is not easy to enter or be blown into the welding molten pool or the area to be welded by the shielding gas, further ensuring a dry welding environment.

[0029] When welding is in progress, the water-cooling gun bracket 7 drives the water-cooling gun 6 to follow the welding gun 1 to move synchronously on the guide rail 4 along the welding direction, and the sliding speed of the water-cooling gun bracket 7 can be precisely adjusted under the control of the numerical control system. At the same time, the water-cooling channel 14 introduces cooling water 11 to cool the weldment. The protective gas 12 in the high-pressure protective gas channel 15 can form a layer of air 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, preventing the cooling water 11 from entering the welding molten pool or wetting the area to be welded and affecting the welding quality.

[0030] A water leakage plate 5 is fixedly connected in the inner cavity of the box body 8, 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 by the water leakage plate 5, and the filtered cooling water 11 can be recycled.

[0031] 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: S1: grinding and cleaning the sample 2 to be welded to remove impurities and oxide layer on the surface, wherein the material of the sample 2 to be welded is hot-formed steel; S2: clamp the sample 2 to be welded at the welding position, the welding joint is a butt welding joint, the welding method is arc welding, the welding gun 1 is connected to the welding machine, cooling water and shielding gas, and the welding parameters are set to ensure that the welding is carried out normally; 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 in the numerical control system, and ensure that the water-cooling gun 6 can be cooled in real time during the welding process; 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, and 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, thereby ensuring the welding quality. S5: Before welding starts, the protective gas 12 is first 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 will not enter the area to be welded. Welding will start 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.

[0032] The present invention adds a water-cooling gun 6 that can move with the welding gun 1 on the back of the sample 2 to be welded during welding. The welding gun 1 and the water-cooling gun 6 are respectively arranged on the front and back of the sample 2 to be welded and aligned with the weld 9 of the sample 2 to be welded. When welding is in progress, the water-cooling gun 6 will move synchronously with the welding gun 1, and cooling water 11 and shielding gas 12 will be introduced into the water-cooling gun 6. The heat-affected zone 10 is forced to be cooled during welding. Due to the water curtain protection generated by the shielding gas 12, the cooling water 11 will not enter the weld 9 to affect the welding quality. Forced cooling will greatly reduce the heat input of the heat-affected zone 10, weaken the softening phenomenon of the tempering zone, and improve the strength of the welded joint.

[0033] 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 specific embodiments, and changes, modifications, additions or substitutions made by ordinary technicians in the field within the essential scope of the present invention should also fall within the protection scope 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 comprises 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 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.

2. The hot-formed steel arc welding device based on forced cooling according to claim 1 is 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 channel or a section of the water cooling channel and the high-pressure shielding gas channel near the outlet end are both arranged as a trumpet-shaped reducing section, 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 in the water cooling channel is located at the rear side of the front end of the outlet end in the high-pressure shielding gas channel.

4. The hot-formed steel arc welding device based on forced cooling according to claim 3 is 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.

5. The hot-formed steel arc welding device based on forced cooling according to claim 4 is 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.

6. The hot-formed steel arc welding device based on forced cooling according to claim 5 is characterized in that: A partition is fixedly connected in the box body, and the partition divides the inner cavity of the box body into a welding area at an upper position and a cooling area at a lower position, 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.

7. The hot-formed steel arc welding device based on forced cooling according to claim 6 is characterized in that: A guide rail is fixedly connected in the box body, and the water-cooling gun bracket is slidably connected to the guide rail.

8. The hot-formed steel arc welding device based on forced cooling according to claim 7 is 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 can be pressed against the side wall of the water-cooling gun to fix the water-cooling gun; A water leakage plate is fixedly connected in 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.

9. A hot-formed steel arc welding method based on forced cooling using the hot-formed steel arc welding device based on forced cooling according to any one of claims 1 to 8, 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 at the welding position. The welding joint is a butt welding joint. Connect the welding gun to the welding machine, cooling water and protective gas. Set the welding parameters to ensure that the welding is carried out normally. 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 cooling water and protective gas to the water-cooling gun. Input 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 can be 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 should be higher than the water pressure and remain stable. S5: Before welding, first introduce the protective gas into the water-cooling gun, and then introduce the cooling water to ensure the isolation effect of the gas, so that the cooling water will not enter 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.

10. The hot-formed steel arc welding method based on forced cooling according to claim 9, characterized in that: In step S4, the air pressure is 0.02-0.04 MPa higher than the water pressure.

Images