Welding tool and process for red copper tube
By designing welding fixtures for copper pipes and optimizing the welding process, the defects in manual argon arc welding of copper pipes were solved, achieving high-quality weld effects and meeting the needs of engineering applications.
Patent Information
- Application Number
- CN202610120099.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-03-31
AI Technical Summary
When manually argon-arc welding copper pipes, especially thick-walled copper pipes, defects such as porosity, lack of fusion, incomplete penetration, and weld beads are easily generated, making it difficult to meet the highest weld quality requirements.
Design a welding fixture for copper tubes, including a base plate and a fixing structure. The copper tube is fixed by the semi-circular holes of the support plate and pressure plate and connected by bolts. With the help of an auxiliary positioning mechanism, the coaxiality and bevel gap are precisely controlled. Combined with the optimized welding process, the TIG welding method and specific current and voltage parameters are used to perform four-point spot welding, root pass welding and fill/cover weld.
It effectively avoids defects such as porosity, lack of fusion, incomplete penetration, and weld beads, ensuring that the weld quality reaches the highest level and providing reliable application of copper pipes in engineering.
Smart Images
Figure CN121755829A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of welding technology, and more specifically, to a welding fixture and process for copper pipes. Background Technology
[0002] In industrial production, copper pipes are widely used in refrigeration, HVAC, and chemical industries due to their excellent thermal conductivity, electrical conductivity, and corrosion resistance. In current welding production processes, copper pipes are frequently connected by welding. However, due to space constraints and production conditions, in some scenarios, the welding method can only be designed as manual argon arc welding. At the same time, many projects require 100% non-destructive testing of copper pipe welds, and the weld quality level must reach the highest level of the corresponding non-destructive testing standard.
[0003] Currently, in the process of manual argon arc welding of copper pipes, it is difficult to control the molten pool during the welding of copper pipes. For thick-walled copper pipes (wall thickness exceeding 3mm), the welding difficulty is even greater. During the welding process, defects such as porosity, lack of fusion, incomplete penetration, and weld beads are very easy to occur. Among them, the control of porosity defects is particularly difficult. These defects do not meet the requirements of the highest weld quality level. Summary of the Invention
[0004] The present invention aims to solve the problems of defects easily generated and difficulty in achieving the highest weld quality level requirements in the existing technology of manual argon arc welding of copper tubes.
[0005] To solve the above problems, the present invention provides a welding fixture for copper tubes, including a base plate, wherein fixing structures are provided on the top left and right sides of the base plate; The fixing structure includes a support plate, a pressure plate, and bolts. The pressure plate is bolted to the top of the support plate, and the bottom of the support plate is welded to the base plate. The top of the support plate and the bottom of the pressure plate are both provided with semi-circular holes.
[0006] The welding fixture for copper tubes provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: The welding fixture for this copper tube involves placing the copper tube on a support plate and passing it through a semi-circular hole. A pressure plate, through its bottom semi-circular hole, is then fitted onto the top of the support plate, corresponding to the copper tube. One copper tube is installed on each of the two fixed structures sequentially. After adjusting the welding distance between the two copper tubes, the pressure plate and support plate are connected and tightened by screwing bolts, further securing the copper tube. This welding fixture ensures the coaxiality of the copper tubes during assembly, preventing misalignment during bevel assembly. It also serves to fix the copper tube during welding, reducing welding deformation. During assembly, a thin copper pad can be used in the semi-circular hole of the fixture to adjust the coaxiality of the copper tube, ensuring pre-welding assembly quality and thus guaranteeing welding quality.
[0007] Furthermore, the fixing structure also includes an auxiliary positioning mechanism, which includes a threaded column, a handle connected to the top of the threaded column, a sleeve connected to the external thread of the threaded column, the sleeve being fitted and installed on the top of the pressure plate, and an arc-shaped positioning block rotatably connected to the bottom of the threaded column. The arc-shaped positioning block is slidably connected to the pressure plate and is used to move up and down in the semi-circular hole at the bottom of the pressure plate.
[0008] Furthermore, positioning pins are provided on both the front and rear sides of the semi-circular hole at the bottom of the pressure plate, and a positioning pin hole is provided on the top of the support plate. One end of the positioning pin is connected to the pressure plate, and the other end is inserted into the positioning pin hole.
[0009] Furthermore, the top of the pressure plate is provided with a through hole that mates with a bolt, and the top of the support plate is provided with a threaded hole that mates with a bolt, with the through hole and the threaded hole being positioned corresponding to each other.
[0010] Furthermore, the coaxiality of the semi-circular holes at the top of the two support plates is ≤0.5mm.
[0011] This invention also provides a welding process for copper tubes, based on the welding fixture for copper tubes as described above, including: Step 1, Pre-welding preparation: Ultrasonic cleaning and drying of copper pipe, welding wire, and welding fixture; cleaning of the oxide layer at the bevel end and surrounding area of copper pipe with an electric grinder, followed by cleaning with anhydrous ethanol; diluting an appropriate amount of flux with anhydrous ethanol into a paste and applying it to the bevel, leaving the rest for later use. Step 2, Tooling Assembly: Place the copper tube on the support plate of the welding tooling, cover the pressure plate and connect it to the support plate with bolts, adjust the position of the copper tube in the semi-circular hole, tighten the bolts, and fix one copper tube on each of the two fixed structures in turn. Step 3, Gas Pretreatment: Install the back shielding gas tube into the inner hole of the copper tube and fix it with adhesive aluminum foil. Introduce Ar back shielding gas and adjust the flow rate to the range of 5~15L / min. Pre-introduce for a period of time. Turn on the welding machine and the arc shielding gas, and adjust the Ar gas flow rate to the range of 8~15L / min. Step 4, Positioning Welding: Use TIG welding method and DCEN electrode type. Adjust the welding current to the range of 180~200A and the arc voltage to the range of 12-18V. Fill with metal and preheat the assembled copper tube directly with argon arc welding arc. After the bevel melts and forms a molten pool, use welding wire dipped in paste flux to perform four-point spot welding for fixation. Step 5, root pass welding: Keep the TIG welding method and DCEN electrode type unchanged, adjust the welding current to the range of 180~200A, adjust the arc voltage to the range of 15-20V, dip the welding wire in the paste flux to weld the filler metal, the welding speed is 50-80mm / min, and perform root pass welding from the three o'clock and nine o'clock directions upwards. After loosening the bolts in the tooling and adjusting the position of the copper tube, tighten the bolts to limit the position, and continue welding the remaining part in the same way as above. Step 6, Fill / Cover Welding: After the root pass welding is completed, clean the oxide layer on the weld surface with a stainless steel wire brush. After the temperature drops to room temperature, apply diluted flux to the root pass weld and bevel surface. Use the same process parameters as the root pass welding, and dip the welding wire in paste flux before welding to perform fill / cover welding. Step 7, Post-weld treatment: After welding, use a stainless steel wire brush to clean the oxide layer on the weld surface again, and clean it after the weld has cooled to room temperature. Step 8, Inspection: Perform 100% VT, PT, RT non-destructive testing on the weld.
[0012] This invention also provides a welding process for copper tubes, which, compared to existing technologies, has, but is not limited to, the following beneficial effects: The welding process for this copper pipe is based on the welding fixture for copper pipes described above. Its simple structure and reasonable design enable precise assembly and stable fixation of the copper pipe, effectively controlling assembly coaxiality and bevel gap, and reducing welding deformation. Combined with the optimized welding process, through the rational selection of welding materials, design of welding joints, establishment of welding sequence and process parameters, and standardized pre-welding, during-welding, and post-welding operations, defects such as porosity, lack of fusion, incomplete penetration, and weld beads, which are prone to occur in manual argon arc welding of copper pipes, are effectively avoided. This ensures that the weld quality, after verification by non-destructive testing, reaches the highest level of the corresponding standard, providing a strong guarantee for the reliable application of copper pipes in engineering projects and possessing broad prospects for widespread application.
[0013] Furthermore, in step 1, one end of the copper pipe to be welded is first machined into a bevel shape using a lathe, and the bevel angle of the weld joint between the two copper pipes is 60°±10°.
[0014] Furthermore, in step 1, an electric grinding head is used to clean the bevel end of the copper tube, the inner hole of the bevel, and the oxide layer within a certain range from the bevel.
[0015] Furthermore, in step 2, when the pressure plate is closed, the positioning pin at its bottom is inserted into the corresponding positioning pin hole on the support plate for initial positioning; then, a bolt is inserted into the through hole on the pressure plate and screwed through to the threaded hole on the support plate to further connect the pressure plate and the support plate. During assembly, a thin copper pad is used to adjust the coaxiality of the copper tube in the semi-circular hole of the tooling, and / or an auxiliary positioning mechanism is used to further assemble and fix the copper tube, with the bevel gap between the two copper tubes controlled at 2mm to 3mm.
[0016] Further, in step 5, the first weld segment is welded by starting an arc at three points using welding wire dipped in flux paste, and ending the arc at the 12 o'clock position. Then, the second weld segment is welded by starting an arc at nine o'clock using welding wire dipped in flux paste, and ending the arc at the 12 o'clock position, with the ending position passing over the ending point of the first weld segment and pausing for a few seconds at the junction of the two weld segments. After loosening the bolts and / or auxiliary positioning mechanism in the tooling and adjusting the position of the copper tube, the bolts are tightened for limiting, and / or, the auxiliary positioning mechanism is used for further fixation. The third weld segment is welded by starting an arc at three points using welding wire dipped in flux paste, and ending the arc at the 12 o'clock position. Then, the fourth weld segment is welded by starting an arc at nine o'clock using welding wire dipped in flux paste, and ending the arc at the 12 o'clock position, with the ending position passing over the ending point of the third weld segment and pausing for a few seconds at the junction of the two weld segments. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the welding fixture for copper tubes according to an embodiment of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the welding fixture for copper tubes according to an embodiment of the present invention. Figure 2 ; Figure 3 Embodiments of the present invention Figure 2 Rear view; Figure 4 This is a schematic diagram of the welding fixture for copper tubes according to an embodiment of the present invention. Figure 3 ; Figure 5 Embodiments of the present invention Figure 4 A schematic diagram of the structure of the pressure plate in the middle; Figure 6This is a schematic diagram of the usage state structure of the auxiliary positioning mechanism according to an embodiment of the present invention. Figure 1 ; Figure 7 This is a schematic diagram of the usage state structure of the auxiliary positioning mechanism according to an embodiment of the present invention. Figure 2 ; Figure 8 This is a schematic diagram of the connection structure between the base plate and the support plate in an embodiment of the present invention; Figure 9 This is a diagram showing the welding sequence of copper tubes according to an embodiment of the present invention.
[0018] Explanation of reference numerals in the attached figures: 1. Base plate; 2. Support plate; 3. Pressure plate; 301. Through hole; 302. Mounting hole; 303. Slide groove; 4. Bolt; 5. Semicircular hole; 6. Auxiliary positioning mechanism; 601. Threaded post; 602. Handle; 603. Sleeve; 604. Arc-shaped positioning block; 7. Positioning pin; 8. Positioning pin hole; 9. Threaded hole; 10. First section weld; 11. Second section weld; 12. Third section weld; 13. Fourth section weld. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings showing multiple embodiments according to this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.
[0020] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in the description of this application is for the purpose of describing specific embodiments only and is not intended to limit the use of open-ended terms such as "comprising," "including," "having," "containing," etc., in the description, claims, and accompanying drawings. Therefore, "comprising," "including," or "having" refers to, for example, a method or apparatus having one or more steps or elements, but not limited to having only these one or more elements. The terms "first," "second," etc., in the description, claims, or accompanying drawings are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0022] Furthermore, in the attached diagram, the X-axis represents the vertical direction, that is, the front-to-back position, and the positive direction of the X-axis (that is, the direction the arrow points to) represents the front, and the negative direction of the X-axis (that is, the direction opposite to the positive direction of the X-axis) represents the back. In the attached diagram, the Y-axis represents the horizontal direction, that is, the left-to-right position, and the positive direction of the Y-axis (that is, the direction the arrow points to) represents the left, and the negative direction of the Y-axis (that is, the direction opposite to the positive direction of the Y-axis) represents the right. In the attached diagram, the Z-axis represents the vertical direction, that is, the up-to-down position, and the positive direction of the Z-axis (that is, the direction the arrow points to) represents the up, and the negative direction of the Z-axis (that is, the direction opposite to the positive direction of the Z-axis) represents the down.
[0023] It should also be noted that the aforementioned X-axis, Y-axis and Z-axis are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.
[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be a direct connection or an indirect connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0025] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.
[0026] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0027] Example 1, see Figure 1 and Figure 2 The present invention provides a welding fixture for copper tubes, including a base plate 1, and fixing structures are provided on the top left and right sides of the base plate 1. The fixing structure includes a support plate 2, a pressure plate 3, and bolts 4. The pressure plate 3 is connected to the top of the support plate 2 by bolts 4, and the bottom of the support plate 2 is welded to the base plate 1. The top of the support plate 2 and the bottom of the pressure plate 3 are both provided with semi-circular holes 5.
[0028] In this embodiment, the welding fixture for the copper tube is used by placing the copper tube on the support plate 2 and passing it through the semi-circular hole 5. Then, the pressure plate 3 is fitted onto the top of the support plate 2 through the semi-circular hole 5 at the bottom, corresponding to the copper tube. One copper tube is installed on each of the two fixed structures in turn. After adjusting the welding distance between the two copper tubes, the pressure plate 3 and the support plate 2 are connected and tightened by tightening the bolts 4 to further fix the copper tube. This welding fixture ensures the coaxiality of the copper tubes in the assembly, avoiding misalignment of the bevel assembly. At the same time, this fixture also plays a role in fixing the copper tubes during the welding process, reducing welding deformation. During the assembly process, a thin copper pad can be used in the semi-circular hole 5 of the fixture to adjust the coaxiality of the copper tubes to ensure the pre-welding assembly quality and thus the welding quality.
[0029] It should be noted that the welding fixture is made of 316L stainless steel, which has good corrosion resistance and structural stability.
[0030] See Figures 4-7 Optionally, the fixing structure also includes an auxiliary positioning mechanism 6, which includes a threaded post 601. A handle 602 is connected to the top of the threaded post 601, and a sleeve 603 is threaded to the outside of the threaded post 601. The sleeve 603 is fitted and installed on the top of the pressure plate 3. An arc-shaped positioning block 604 is rotatably connected to the bottom of the threaded post 601. The arc-shaped positioning block 604 is slidably connected to the pressure plate 3 and is used to move up and down in the semi-circular hole 5 at the bottom of the pressure plate 3.
[0031] In this embodiment, the threaded post 601 is screwed onto the sleeve 603 by the hand handle 602. The threaded drive drives the arc-shaped positioning block 604 to slide up and down on the pressure plate 3. When sliding down, the arc-shaped positioning block 604 enters the semi-circular hole 5 at the bottom of the pressure plate 3. The arc-shaped positioning block 604 continues to enter and presses against the copper tube fixed between the support plate 2 and the pressure plate 3 through its arc-shaped bottom surface. This facilitates further auxiliary positioning of the copper tube and improves the stability and coaxiality of the copper tube during welding.
[0032] Specifically, the sleeve 603 is composed of a cylindrical part and a prism part, and has a threaded hole inside that mates with the threaded post 601. The top of the pressure plate 3 has an insertion hole 302 that mates with the sleeve 603 for inserting the sleeve 603. The sleeve 603 and the insertion hole 302 are interference fit, which limits the sleeve 603 after it is inserted into the top of the pressure plate 3, reducing the possibility of slippage when the threaded post 601 is screwed on. A groove 303 is provided at the top of the semi-circular hole 5 at the bottom of the pressure plate 3. The groove 303 is connected to the mounting hole 302 and the semi-circular hole 5 at the bottom of the pressure plate 3, respectively, so that the arc-shaped positioning block 604 can slide into or retract into the groove 303 in the semi-circular hole 5 at the bottom of the pressure plate 3.
[0033] See Figure 5 , Figure 6 and Figure 8 Optionally, positioning pins 7 are provided on both the front and rear sides of the semi-circular hole 5 at the bottom of the pressure plate 3, and positioning pin holes 8 are provided on the top of the support plate 2. One end of the positioning pin 7 is connected to the pressure plate 3, and the other end is inserted into the positioning pin hole 8.
[0034] In this embodiment, when the pressure plate 3 is installed on the support plate 2, the positioning pin 7 at the bottom of the pressure plate 3 is inserted into the corresponding positioning pin hole 8 on the support plate 2, which facilitates the initial longitudinal positioning of the pressure plate 3 when it is installed on the support plate 2, and makes it convenient to connect the two by tightening the bolt 4.
[0035] See Figure 5 , Figure 6 and Figure 8Optionally, the top of the pressure plate 3 is provided with a through hole 301 that mates with the bolt 4, and the top of the support plate 2 is provided with a threaded hole 9 that mates with the bolt 4. The positions of the through hole 301 and the threaded hole 9 are corresponding.
[0036] In this embodiment, after the pressure plate 3 is covered and positioned on the support plate 2, the bolt 4 is first inserted into the through hole 301, and then the bolt 4 is screwed into the threaded hole 9 to achieve the connection between the pressure plate 3 and the support plate 2. The bolt 4 is continuously screwed until it can no longer be screwed to achieve the fastening between the pressure plate 3 and the support plate 2.
[0037] See Figure 1 Optionally, the coaxiality of the semi-circular holes 5 at the top of the two support plates 2 is ≤0.5mm.
[0038] In this embodiment, after the support plate 2 and the base plate 1 are connected by welding, the semi-circular hole 5 is machined. During the manufacturing process, it is necessary to ensure that the coaxiality of the two semi-circular holes 5 used for support is no more than 0.5mm, so as to further ensure the coaxiality of the copper tube of the welded workpiece during assembly and avoid misalignment of the bevels of the two copper tubes.
[0039] Example 2, another embodiment of the present invention, a welding process for a copper tube, based on the aforementioned copper tube welding fixture, includes: Step 1, Pre-welding preparation: Ultrasonic cleaning and drying of copper pipe, welding wire, and welding fixture; cleaning of the oxide layer at the bevel end and surrounding area of copper pipe with an electric grinder, followed by cleaning with anhydrous ethanol; diluting an appropriate amount of flux with anhydrous ethanol into a paste and applying it to the bevel, leaving the rest for later use. Step 2, Tooling Assembly: Place the copper tube on the support plate 2 of the welding tooling, cover the pressure plate 3 and connect it to the support plate 2 with bolts 4, adjust the position of the copper tube in the semi-circular hole 5, tighten the bolts 4, and fix one copper tube on each of the two fixed structures in turn. Step 3, Gas Pretreatment: Install the back shielding gas tube into the inner hole of the copper tube and fix it with adhesive aluminum foil. Introduce Ar back shielding gas and adjust the flow rate to the range of 5~15L / min. Pre-introduce for a period of time. Turn on the welding machine and the arc shielding gas. Adjust the Ar gas flow rate to the range of 8~15L / min to ensure that both sides of the weld can be effectively protected and avoid oxidation defects. Step 4, Positioning Welding: Use TIG welding method and DCEN electrode type. Adjust the welding current to the range of 180~200A and the arc voltage to the range of 12-18V. Fill with metal and preheat the assembled copper tube directly with argon arc welding arc. After the bevel melts and forms a molten pool, use welding wire dipped in paste flux to perform four-point spot welding for fixation. Step 5, root pass welding: Keep the TIG welding method and DCEN electrode type unchanged, adjust the welding current to the range of 180~200A, adjust the arc voltage to the range of 15-20V, dip the welding wire in the paste flux to weld the filler metal, the welding speed is 50-80mm / min, and perform root pass welding from the three o'clock and nine o'clock directions upwards. After loosening the bolt 4 in the tooling and adjusting the position of the copper tube, tighten the bolt 4 to limit the position, and continue welding the remaining part in the same way as above. Step 6, Fill / Cover Welding: After the root pass welding is completed, clean the oxide layer on the weld surface with a stainless steel wire brush. After the temperature drops to room temperature, apply diluted flux to the root pass weld and bevel surface. Use the same process parameters as the root pass welding, and dip the welding wire in paste flux before welding to perform fill / cover welding. Step 7, Post-weld treatment: After welding, use a stainless steel wire brush to clean the oxide layer on the weld surface again, and clean it after the weld has cooled to room temperature. Step 8, Inspection: Perform 100% VT, PT, RT non-destructive testing on the weld.
[0040] In this embodiment, the welding process of the copper pipe is based on the welding fixture for copper pipes as described above. Its structure is simple and reasonably designed, which can realize the precise assembly and stable fixation of the copper pipe, effectively control the assembly coaxiality and bevel gap, and reduce welding deformation. In addition, with the optimized welding process, by reasonably selecting welding materials, designing welding joints, formulating welding sequence and process parameters, and standardizing pre-welding, welding and post-welding operations, defects such as porosity, lack of fusion, incomplete penetration and weld beads that are easy to occur in manual argon arc welding of copper pipes are effectively avoided. After verification by non-destructive testing, the weld quality can reach the highest level of the corresponding standard, which provides a strong guarantee for the reliable application of copper pipes in engineering and has broad prospects for promotion and application.
[0041] It should be noted that the maximum heat input for filler / cover welding is dynamically adjusted according to the actual welding conditions to ensure the quality of weld formation.
[0042] See Figure 3 Optionally, in step 1, one end of the copper pipe to be welded is first machined into a bevel shape using a lathe, and the bevel angle of the weld joint between the two copper pipes is 60°±10°.
[0043] In this embodiment, before welding the copper tubes, one end is machined into a bevel shape using a lathe, and the bevel angle of the welding joint between the two copper tubes is within the range of 60°±10°, to ensure that the molten pool can be fully filled during the welding process and improve the fusion quality of the weld.
[0044] Optionally, in step 1, an electric grinding head is used to clean the bevel end of the copper tube, the inner hole of the bevel, and the oxide layer within a certain range from the bevel.
[0045] In this embodiment, the oxide layer at the weld joint is removed over a large area to ensure the quality of subsequent welding.
[0046] Optionally, in step 2, when the pressure plate 3 is closed, the positioning pin 7 at its bottom is inserted into the corresponding positioning pin hole 8 on the support plate 2 to initially position the pressure plate 3 when it is closed on the support plate 2; then, the bolt 4 is inserted into the through hole 301 on the pressure plate 3 and screwed through to the threaded hole on the support plate 2 to further connect the pressure plate 3 and the support plate 2. During assembly, a thin copper pad is used to adjust the coaxiality of the copper tube in the semi-circular hole 5 of the tooling, and / or, an auxiliary positioning mechanism 6 is used to further assemble and fix the copper tube, so that the coaxiality of the copper tube assembly is no more than 0.5mm, and the bevel gap between the two copper tubes is controlled between 2mm and 3mm.
[0047] See Figure 9 Optionally, in step 5, first use welding wire dipped in flux to start arc welding the first weld 10 from three points, welding to the 12 o'clock position and then ending the arc. Then use welding wire dipped in flux to start arc welding the second weld 11 from the 9 o'clock position, welding to the 12 o'clock position and ending the arc, with the ending position pressing past the ending point of the first weld 10 and pausing for a few seconds at the junction of the two welds. Loosen the bolt 4 and / or the auxiliary positioning mechanism 6 in the tooling, adjust the position of the copper tube, tighten the bolt 4 for limiting, and / or use the auxiliary positioning mechanism 6 for further fixation. First use welding wire dipped in flux to start arc welding the third weld 12 from three points, welding to the 12 o'clock position and then ending the arc. Then use welding wire dipped in flux to start arc welding the fourth weld 13 from the 9 o'clock position, welding to the 12 o'clock position and ending the arc, with the ending position pressing past the ending point of the third weld 12 and pausing for a few seconds at the junction of the two welds.
[0048] Example 3: Selecting a workpiece with the following dimensions. For a 19mm × 4.5mm (wall thickness) × 500mm copper pipe, S201 welding wire and CJ301 flux are used. Based on the welding fixtures and welding process mentioned above (i.e., the single-sided welding double-sided forming process of manual argon arc welding), the specific welding process parameters are shown in the table below.
[0049]
[0050] Step 1, Pre-welding preparation: First, machine one end of the copper pipe to be welded into a bevel shape using a lathe. The bevel angle of the weld joint between the two copper pipes is 60°. The copper tube, S201 welding wire, and welding fixture were ultrasonically cleaned and dried. The oxide layer on the bevel end of the copper tube, the inner hole of the bevel within 15mm and the area within 20mm from the bevel was cleaned with an electric grinder, and then cleaned with anhydrous ethanol. An appropriate amount of CJ301 flux was diluted with anhydrous ethanol into a paste and applied to the bevel, covering the bevel by about 5mm.
[0051] Step 2, Tooling Assembly: Place the copper tube on the support plate 2 of the welding fixture, cover the pressure plate 3 and connect it to the support plate 2 with bolts 4, adjust the position of the copper tube in the semi-circular hole 5, tighten the bolts 4, and fix one copper tube on each of the two fixed structures in turn; during the assembly process, use a thin copper pad in the semi-circular hole 5 of the fixture to adjust the coaxiality of the copper tube, and use the auxiliary positioning mechanism 6 to further assemble and fix the copper tube, and control the bevel gap between the two copper tubes to 2mm.
[0052] Step 3, Gas Pretreatment: Install the back shielding gas tube into the inner hole of the copper tube and fix it with adhesive aluminum foil. Introduce Ar back shielding gas, adjust the flow rate to 5L / min, and pre-introduce for 5 minutes; turn on the welding machine and the arc shielding gas, and adjust the Ar gas flow rate to 10L / min.
[0053] Step 4, Positioning Welding: Use TIG welding method, DCEN electrode type, welding current adjusted to 180A, arc voltage adjusted to 15V, filler metal, welding wire diameter Φ2.0mm, preheat the assembled copper tube directly with argon arc welding arc, and after seeing the bevel melt to form a molten pool, use welding wire dipped in paste CJ301 flux to perform four-point spot welding for fixation.
[0054] Step 5, Root Pass Welding: Keeping the TIG welding method and DCEN electrode type unchanged, adjust the welding current to 200A and the arc voltage to 20V. Dip the welding wire in CJ301 flux paste for filler metal welding at a welding speed of 50mm / min. First, use the welding wire dipped in CJ301 flux paste to start the arc from three points to weld the first section of weld 10, and finish welding at the 12 o'clock position. Then, use the welding wire dipped in CJ301 flux paste to start the arc from the 9 o'clock position to weld the second section of weld 11, and finish welding at the 12 o'clock position, ensuring the finish position overlaps the finish point of the first section of weld 10. 5mm and stay at the junction of the two weld sections for 5s; loosen the bolt 4 and auxiliary positioning mechanism 6 in the tooling, adjust the position of the copper tube, tighten the bolt 4 for limit, and use the auxiliary positioning mechanism 6 for further fixation. First, use the welding wire dipped in the paste CJ301 flux to start the arc from three points to weld the third weld section 12, and finish the arc at the 12 o'clock position. Then, use the welding wire dipped in the paste CJ301 flux to start the arc from the 9 o'clock position to weld the fourth weld section 13, and finish the arc at the 12 o'clock position. The arc-finishing position should be 5mm past the arc-finishing point of the third weld section 12 and stay at the junction of the two weld sections for 5s.
[0055] Step 6, Fill / Cover Welding: After the root pass welding is completed, clean the oxide layer on the weld surface with a stainless steel wire brush. After the temperature drops to room temperature, apply diluted flux to the root pass weld and bevel surface. Use the same process parameters as the root pass welding, and dip the welding wire in paste CJ301 flux before filling / cover welding. Step 7, Post-weld treatment: After welding, use a stainless steel wire brush to clean the oxide layer on the weld surface again, and clean it after the weld has cooled to room temperature. Step 8, Inspection: Perform 100% VT, PT, RT non-destructive testing on the weld. There should be no defects such as porosity. The inspection requirements are all the highest level of the standard corresponding to the weld. The inspection results meet the quality design requirements. The specific inspection contents are shown in the table below.
[0056]
[0057] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A welding fixture for copper pipes, characterized in that, Includes a base plate (1), and the top left and right sides of the base plate (1) are provided with fixing structures; The fixing structure includes a support plate (2), a pressure plate (3) and bolts (4). The pressure plate (3) is connected to the top of the support plate (2) by bolts (4), and the bottom of the support plate (2) is welded to the base plate (1). The top of the support plate (2) and the bottom of the pressure plate (3) are both provided with semi-circular holes (5).
2. The welding fixture for copper pipes according to claim 1, characterized in that, The fixed structure also includes an auxiliary positioning mechanism (6), which includes a threaded post (601). The top end of the threaded post (601) is connected to a handle (602). The external thread of the threaded post (601) is connected to a sleeve (603). The sleeve (603) is fitted and installed on the top of the pressure plate (3). The bottom end of the threaded post (601) is rotatably connected to an arc-shaped positioning block (604). The arc-shaped positioning block (604) is slidably connected to the pressure plate (3) and is used to move up and down in the semi-circular hole (5) at the bottom of the pressure plate (3).
3. The welding fixture for copper pipes according to claim 1, characterized in that, Positioning pins (7) are provided on both the front and rear sides of the semi-circular hole (5) at the bottom of the pressure plate (3). The top of the support plate (2) is provided with a positioning pin hole (8). One end of the positioning pin (7) is connected to the pressure plate (3), and the other end is inserted into the positioning pin hole (8).
4. The welding fixture for copper pipes according to claim 1, characterized in that, The pressure plate (3) has a through hole (301) at the top that mates with the bolt (4), and the support plate (2) has a threaded hole (9) at the top that mates with the bolt (4). The through hole (301) and the threaded hole (9) are positioned opposite each other.
5. The welding fixture for copper pipes according to claim 1, characterized in that, The coaxiality of the semi-circular holes (5) at the top of the two support plates (2) is ≤0.5mm.
6. A welding process for copper pipes, characterized in that, The welding fixture for copper pipes as described in any one of claims 1-5 includes: Step 1, Pre-welding preparation: Ultrasonic cleaning and drying of copper pipe, welding wire, and welding fixture; cleaning of the oxide layer at the bevel end and surrounding area of copper pipe with an electric grinder, followed by cleaning with anhydrous ethanol; diluting an appropriate amount of flux with anhydrous ethanol into a paste and applying it to the bevel, leaving the rest for later use. Step 2, Tooling Assembly: Place the copper tube on the support plate (2) of the welding tooling, cover the pressure plate (3) and connect it to the support plate (2) with bolts (4), adjust the position of the copper tube in the semi-circular hole (5), tighten the bolts (4) to secure it, and fix one copper tube on each of the two fixed structures in turn. Step 3, Gas Pretreatment: Install the back shielding gas tube into the inner hole of the copper tube and fix it with adhesive aluminum foil. Introduce Ar back shielding gas and adjust the flow rate to the range of 5~15L / min. Pre-introduce for a period of time. Turn on the welding machine and the arc shielding gas, and adjust the Ar gas flow rate to the range of 8~15L / min. Step 4, Positioning Welding: Use TIG welding method and DCEN electrode type. Adjust the welding current to the range of 180~200A and the arc voltage to the range of 12-18V. Fill with metal and preheat the assembled copper tube directly with argon arc welding arc. After the bevel melts and forms a molten pool, use welding wire dipped in paste flux to perform four-point spot welding for fixation. Step 5, root pass welding: Keep the TIG welding method and DCEN electrode type unchanged, adjust the welding current to the range of 180~200A, adjust the arc voltage to the range of 15-20V, dip the welding wire in the paste flux to weld the filler metal, the welding speed is 50-80mm / min, and perform root pass welding from the three o'clock and nine o'clock directions upwards. After loosening the bolt (4) in the tooling and adjusting the position of the copper tube, tighten the bolt (4) to limit the position, and continue welding the remaining part in the same way as above. Step 6, Fill / Cover Welding: After the root pass welding is completed, clean the oxide layer on the weld surface with a stainless steel wire brush. After the temperature drops to room temperature, apply diluted flux to the root pass weld and bevel surface. Use the same process parameters as the root pass welding, and dip the welding wire in paste flux before welding to perform fill / cover welding. Step 7, Post-weld treatment: After welding, use a stainless steel wire brush to clean the oxide layer on the weld surface again, and clean it after the weld has cooled to room temperature. Step 8, Inspection: Perform 100% VT, PT, RT non-destructive testing on the weld.
7. The welding process for copper pipes according to claim 6, characterized in that, In step 1, one end of the copper pipe to be welded is first machined into a bevel shape using a lathe, and the bevel angle of the weld joint between the two copper pipes is 60°±10°.
8. The welding process for copper pipes according to claim 6, characterized in that, In step 1, an electric grinding head is used to clean the bevel end of the copper tube, the inner hole of the bevel, and the oxide layer within a certain range from the bevel.
9. The welding process for copper pipes according to claim 6, characterized in that, In step 2, when the pressure plate (3) is closed, the positioning pin (7) at its bottom is inserted into the corresponding positioning pin hole (8) on the support plate (2) for initial positioning; then the bolt (4) is inserted into the through hole (301) on the pressure plate (3) and screwed into the threaded hole on the support plate (2) to further connect the pressure plate (3) and the support plate (2); During the assembly process, the coaxiality of the copper tube is adjusted in the semi-circular hole (5) of the tooling using a thin copper pad, and / or the copper tube is further assembled and fixed using an auxiliary positioning mechanism (6), with the bevel gap between the two copper tubes controlled at 2mm to 3mm.
10. The welding process for copper pipes according to claim 6, characterized in that, In step 5, the first section of weld (10) is started by applying welding wire to the flux paste and welding from three points. The welding is stopped at the 12 o'clock position. Then, the second section of weld (11) is started by applying welding wire to the flux paste and welding from the 9 o'clock position. The welding is stopped at the 12 o'clock position, and the stopping position is over the stopping point of the first section of weld (10) and lingers for a few seconds at the junction of the two sections of weld. The bolts (4) and / or the auxiliary positioning mechanism (6) in the tooling are loosened, and the copper pipe is adjusted. After positioning, tighten the bolt (4) to limit the position, and / or use the auxiliary positioning mechanism (6) to further fix it. First, dip the welding wire in the paste flux and start the arc from three points to weld the third section of the weld (12). Weld to the 12 o'clock position and then stop the arc. Then dip the welding wire in the paste flux and start the arc from the 9 o'clock position to weld the fourth section of the weld (13). Weld to the 12 o'clock position and stop the arc. The arc-stopping position passes the arc-stopping point of the third section of the weld (12) and stays at the junction of the two sections of the weld for a few seconds.