Positioning welding method for aluminum alloy pipe

Abstract

The invention discloses an aluminum alloy pipe positioning welding method which comprises the following steps that two aluminum alloy pipes are prepared, the outer diameter of each pipe is D, butt joint of welding connectors can be completed through linear cutting and abrasive paper polishing, the widest position of a connector gap is smaller than or equal to 0.2 mm, and after butt joint, the whole aluminum alloy pipes are in a straight state; the plane of the welding gap is vertical to the length direction of the pipe; and oil stains and attached impurities on the surface of the pipe are removed through ultrasonic cleaning. The welding seam of the aluminum alloy pipe can be effectively positioned, and it is ensured that the welding position is accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of welding, and more specifically, to a positioning welding method for an aluminum alloy pipe. Background Art

[0002] Aluminum and aluminum alloys have the characteristics of strong thermal conductivity and large heat capacity, large linear expansion coefficient, low melting point and low high temperature strength. Aluminum alloy welding is a welding process with a relatively high difficulty coefficient among all welding processes. Specifically, the weld is prone to cracks, pores, insufficient penetration, poor forming, slag inclusions and large welding deformation. Among them, the presence of aluminum oxide film on the welding base material seriously affects the quality of the weld, which may lead to defects such as insufficient weld penetration, poor forming and slag inclusions. The main means currently used for aluminum welding are inert gas shielded arc welding, high vacuum brazing, laser welding, etc. Among them, inert gas shielded arc welding has high requirements for operators during the welding process, poor process stability and repeatability, strict pre-weld treatment of the weld surface, and high cost of inert gas use. High vacuum brazing has very strict requirements on the flatness, smoothness and fit of the aluminum alloy welding surface, and is prone to defects such as leaking welds. High vacuum brazing requires a series of complex key steps such as solder selection, solder preparation, solder filling, workpiece assembly, and brazing temperature and time setting. It is easy to cause thermal effects on the aluminum alloy substrate or welding misalignment and other defects to cause failure. Laser welding is a welding technology that has emerged in recent years. It has the advantages of high energy density and high penetration ratio. The laser welding head can complete the welding of complex parts with the assistance of a manipulator. However, due to the strong thermal conductivity and large heat capacity of aluminum alloy itself, large linear expansion coefficient, low melting point and low high temperature strength, high energy density laser beams are prone to excessive heat affected zones, deformation, cracking and other failures when welding on aluminum alloys. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a positioning welding method for aluminum alloy pipes.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] The present invention discloses a positioning welding method for an aluminum alloy pipe, comprising the following steps:

[0006] Step 1: Prepare two aluminum alloy pipes with an outer diameter of D. Use wire cutting and sandpaper grinding to make the welding interface dockable. The widest part of the interface gap is ≤0.2mm. After docking, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe.

[0007] Step 2: Use ultrasonic cleaning to remove oil stains and attached impurities on the surface of the pipe;

[0008] Step 3: Place the cleaned aluminum alloy pipe in an oven for drying;

[0009] Step 4: Punch holes at intervals in the middle of the width of the high-temperature tape. The punch radius r is 2mm-3mm. The distance between the center of the first hole and the starting point of the high-temperature tape is greater than r and less than 0.25πD-r. The distance between the punch centers is 0.25πD. The reserved length of the high-temperature tape should be enough to wrap around the aluminum alloy pipe for more than 5 turns.

[0010] Step 5: Take out the aluminum alloy pipe dried in step 3, align and close the two ends of the welding interface, and the widest part of the interface gap is ≤0.2mm. Fix it with high-temperature tape, align the middle of the high-temperature tape width with the welding gap, wrap it for more than 5 circles, and leave four evenly distributed holes, each hole corresponds to a positioning welding position;

[0011] Step 6: Put the fixed aluminum alloy pipe into the electron beam welding machine, and further fix it with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding room, and perform positioning welding on the aluminum alloy pipe through the reserved holes on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape, and perform welding operations on the four positioning welding positions in turn according to the same process parameters;

[0012] Step 7: Take out the aluminum alloy pipe after positioning welding from the welding chamber of the electron beam welder, tear off the high-temperature tape originally used for fixing, and then use ultrasonic cleaning to remove the impurities such as glue remaining on the surface of the pipe; put the cleaned pipe into the oven for drying;

[0013] Step 8: The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. The formal welding process parameters are set as follows: gun chamber vacuum degree ≤5×10 -3 Pa, vacuum degree of welding chamber ≤5×10 -3 Pa, filament current is 22A-24A, high voltage is 68kV-80kV, welding beam current is 4mA-6mA per mm of pipe wall thickness, side-rotating chuck speed V is 1000mm / min-1500mm / min, welding time is greater than πD / V, and gun distance is 150mm-200mm;

[0014] Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

[0015] Furthermore, in step 2, ultrasonic cleaning uses alcohol with a concentration of ≥95% as a cleaning solution, the cleaning temperature is 30°C-50°C, and the cleaning time is ≥30min.

[0016] Furthermore, in step three, the drying temperature is 80°C-100°C, and the drying time is ≥60min.

[0017] Furthermore, in step five, the center of the hole on the high temperature tape is on the welding gap and the welding gap can be clearly seen through the hole, and the effective field of view radius of each hole is ≥2mm.

[0018] Furthermore, in step 6, the positioning welding process parameters are set as follows: the vacuum degree of the gun chamber is ≤ 5×10 -3 Pa, vacuum degree of welding chamber ≤5×10 -3 Pa, filament current is 22A-24A, high voltage is 68-80kV, welding beam current is 4mA-6mA for every millimeter of pipe wall thickness, gun distance is 150mm-200mm, and single beam duration is 1s.

[0019] Furthermore, in step seven, ultrasonic cleaning uses alcohol with a concentration of ≥95% as a cleaning solution, the cleaning temperature is 50°C-70°C, and the cleaning time is ≥30min.

[0020] Furthermore, in step seven, the drying temperature is 80° C.-100° C., and the drying time is ≥60 min.

[0021] The beneficial effects of the present invention are: it can effectively avoid the risk of introducing impurities and forming defects in the conventional welding method during the positioning welding of aluminum alloys. At the same time, the fixing method is flexible and can meet the welding positioning requirements of aluminum alloy pipes of different sizes. No customized tooling is required, the cost is low, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of the winding device in this embodiment;

[0023] Figure 2 for Figure 1 The enlarged schematic diagram of point A in the middle;

[0024] Figure 3 It is a partial structural schematic diagram of the winding device in this embodiment;

[0025] Figure 4 Schematic diagram of the structure of the punching mechanism in this embodiment;

[0026] Figure 5 for Figure 4 The enlarged schematic diagram of point A in the middle;

[0027] Figure 6is a side view of the punching mechanism in this embodiment;

[0028] Figure 7 Schematic diagram of the structure of the drive seat in this embodiment;

[0029] Figure 8 A side view of the drive seat in this embodiment;

[0030] Fig. 9 The schematic diagram of the structure of the transmission ball wheel in this embodiment.

[0031] Figure numerals: 1, machine base; 2, rotating base; 3, screw rod; 4, screw rod motor; 5, screw rod slider; 6, driving base; 7, driving block 1; 8, driving shaft 1; 9, wire rod; 10, slider; 11, moving block; 12, rotating shaft 2; 13, driving block 2; 14, driven shaft 1; 15, transmission wheel 2; 16, transmission wheel 3; 17, transmission belt 2; 18, linkage shaft 1; 19, limit strip 1; 20, transmission wheel 1; 21, transmission belt 1; 22, rotating shaft 1; 23, driving wheel 1; 24, base; 25, moving base; 26, rotating shaft 3; 27, driving wheel 2; 28, transmission wheel 4; 29, transmission belt 3; 30 , driving gear; 31, retaining ring; 32, driving shaft 2; 33, driven gear; 34, driven shaft 2; 35, driving bevel gear; 36, rotating seat; 37, half gear; 38, driven bevel gear; 39, limiting seat; 40, lifting plate; 41, connecting rod; 42, rack; 43, guide seat; 44, linkage shaft 2; 45, limiting strip 2; 46, spring 1; 47, buffer plate; 48, spring 2; 49, hand wheel; 50, driving shaft; 51, rotating disk; 52, driving arc plate; 53, connecting frame; 54, driving rod; 55, transmission ball wheel; 56, semicircular groove; 57, driving groove; 58, unwinding frame; 59, tape roll. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Embodiment 1

[0034] A positioning welding method for an aluminum alloy pipe comprises the following steps:

[0035] Step 1: Preparation of aluminum alloy pipe and welding interface. The outer diameter of the pipe is 50mm, the wall thickness is 3mm, and the lengths of the two pipe sections are 250mm and 250mm respectively. Through wire cutting and sandpaper grinding, the welding interface can be connected. The widest part of the interface gap is X max The thickness is 0.18mm. After butt jointing, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe.

[0036] Step 2: Cleaning of aluminum alloy pipes: Remove oil stains and attached impurities on the surface of the pipes through ultrasonic cleaning. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 50°C, and the cleaning time is 30 minutes;

[0037] Step 3: Drying of aluminum alloy pipes: Place the cleaned aluminum alloy pipes in an oven for drying at a temperature of 80°C for 60 minutes.

[0038] Step 4: Preparation of high temperature tape. Prepare high temperature tape of appropriate length according to the size of aluminum alloy pipe. The width of high temperature tape is 100mm. Punch holes in the middle of the width of high temperature tape. The punching radius r is 2mm. The distance a between the center of the first hole and the starting point of the high temperature tape is 30mm. The distance b between the centers of subsequent punching holes from the first hole is 39.25mm. The reserved length Y of high temperature tape is 900mm.

[0039] Step 5: Assembling and fixing the aluminum alloy pipe. Take out the cleaned and dried aluminum alloy pipe, align the two ends of the welding interface and make them as close as possible. The widest part of the interface gap is X max The diameter of the high-temperature tape is 0.18mm. Fix it with the high-temperature tape prepared in step 4. Align the middle of the width of the high-temperature tape with the welding gap. Wrap the aluminum alloy pipe 5 times and then cut off the excess tape and leave four evenly distributed holes. Each hole corresponds to a positioning welding position. The center of the punch hole reserved on the high-temperature tape is on the welding gap and the welding gap can be clearly seen through the hole position. The effective field of view radius of each hole is 2mm;

[0040] Step 6: Position welding of aluminum alloy pipes. Put the fixed aluminum alloy pipes into the electron beam welding machine, and further fix them with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and position weld the aluminum alloy pipes through the holes reserved on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape. Set the positioning welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3Pa, filament current 24A, high voltage 70kV, welding beam current 15mA, gun distance 150mm, single down-beam beam duration 1s, welding operation was performed on four positioning welding positions in sequence according to the same process parameters;

[0041] Step 7: Cleaning of aluminum alloy pipes. Take out the aluminum alloy pipes that have been positioned and welded from the welding chamber of the electron beam welder, tear off the high-temperature tape used for fixing, and then use ultrasonic cleaning to remove the glue and other impurities remaining on the surface of the pipes. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 70°C, and the cleaning time is 30 minutes. Then put the cleaned pipes into the oven for drying, the drying temperature is 80°C, and the drying time is 60 minutes;

[0042] Step 8: Formal welding of the welding gap of the aluminum alloy pipe. The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. Set the formal welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current is 24A, high voltage is 70kV, welding beam current is 15mA, side rotation chuck speed linear speed V is 1000mm / min, welding time is 12s, and gun distance is 150mm;

[0043] Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

[0044] Embodiment 2

[0045] A positioning welding method for an aluminum alloy pipe comprises the following steps:

[0046] Step 1: Preparation of aluminum alloy pipe and welding interface. The outer diameter of the pipe is 50mm, the wall thickness is 5mm, and the lengths of the two pipe sections are 250mm and 250mm respectively. Through wire cutting and sandpaper grinding, the welding interface can be docked. The widest part of the interface gap is X max The thickness is 0.18mm. After butt jointing, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe.

[0047] Step 2: Cleaning of aluminum alloy pipes: Remove oil stains and attached impurities on the surface of the pipes through ultrasonic cleaning. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 50°C, and the cleaning time is 30 minutes;

[0048] Step 3: Drying of aluminum alloy pipes: Place the cleaned aluminum alloy pipes in an oven for drying at a temperature of 80°C for 60 minutes.

[0049] Step 4: Preparation of high temperature tape. Prepare high temperature tape of appropriate length according to the size of aluminum alloy pipe. The width of high temperature tape is 100mm. Punch holes in the middle of the width of high temperature tape. The punching radius r is 2mm. The distance a between the center of the first hole and the starting point of the high temperature tape is 30mm. The distance b between the centers of subsequent punching holes from the first hole is 39.25mm. The reserved length Y of high temperature tape is 900mm.

[0050] Step 5: Assembling and fixing the aluminum alloy pipe. Take out the cleaned and dried aluminum alloy pipe, align the two ends of the welding interface and make them as close as possible. The widest part of the interface gap is X max The diameter of the high-temperature tape is 0.18mm. Fix it with the high-temperature tape prepared in step 4. Align the middle of the width of the high-temperature tape with the welding gap. Wrap the aluminum alloy pipe 5 times and then cut off the excess tape and leave four evenly distributed holes. Each hole corresponds to a positioning welding position. The center of the punch hole reserved on the high-temperature tape is on the welding gap and the welding gap can be clearly seen through the hole position. The effective field of view radius of each hole is 2mm;

[0051] Step 6: Position welding of aluminum alloy pipes. Put the fixed aluminum alloy pipes into the electron beam welding machine, and further fix them with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and position weld the aluminum alloy pipes through the holes reserved on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape. Set the positioning welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current 24A, high voltage 70kV, welding beam current 25mA, gun distance 150mm, single down-beam duration 1s, welding operation was performed on four positioning welding positions in sequence according to the same process parameters;

[0052] Step 7: Cleaning of aluminum alloy pipes. Take out the aluminum alloy pipes that have been positioned and welded from the welding chamber of the electron beam welder, tear off the high-temperature tape used for fixing, and then use ultrasonic cleaning to remove the glue and other impurities remaining on the surface of the pipes. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 70°C, and the cleaning time is 30 minutes. Then put the cleaned pipes into the oven for drying, the drying temperature is 80°C, and the drying time is 60 minutes;

[0053] Step 8: Formal welding of the welding gap of the aluminum alloy pipe. The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. Set the formal welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current is 24A, high voltage is 70kV, welding beam current is 25mA, side rotation chuck speed linear speed V is 1000mm / min, welding time is 12s, and gun distance is 150mm;

[0054] Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

[0055] Embodiment 3

[0056] A positioning welding method for an aluminum alloy pipe comprises the following steps:

[0057] Step 1: Preparation of aluminum alloy pipe and welding interface. The outer diameter of the pipe is 50mm, the wall thickness is 5mm, and the lengths of the two pipe sections are 250mm and 250mm respectively. Through wire cutting and sandpaper grinding, the welding interface can be docked. The widest part of the interface gap is X max The thickness is 0.18mm. After butt jointing, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe.

[0058] Step 2: Cleaning of aluminum alloy pipes: Remove oil stains and attached impurities on the surface of the pipes through ultrasonic cleaning. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 50°C, and the cleaning time is 30 minutes;

[0059] Step 3: Drying of aluminum alloy pipes: Place the cleaned aluminum alloy pipes in an oven for drying at a temperature of 80°C for 60 minutes.

[0060] Step 4: Preparation of high temperature tape. Prepare high temperature tape of appropriate length according to the size of aluminum alloy pipe. The width of high temperature tape is 100mm. Punch holes in the middle of the width of high temperature tape. The punching radius r is 3mm. The distance a between the center of the first hole and the starting point of the high temperature tape is 30mm. The distance b between the centers of subsequent punching holes from the first hole is 39.25mm. The reserved length Y of high temperature tape is 900mm.

[0061] Step 5: Assembling and fixing the aluminum alloy pipe. Take out the cleaned and dried aluminum alloy pipe, align the two ends of the welding interface and make them as close as possible. The widest part of the interface gap is Xmax The diameter of the high-temperature tape is 0.18mm. Fix it with the high-temperature tape prepared in step 4. Align the middle of the width of the high-temperature tape with the welding gap. Wrap the aluminum alloy pipe 5 times and then cut off the excess tape and leave four evenly distributed holes. Each hole corresponds to a positioning welding position. The center of the punch hole reserved on the high-temperature tape is on the welding gap and the welding gap can be clearly seen through the hole position. The effective field of view radius of each hole is 3mm;

[0062] Step 6: Position welding of aluminum alloy pipes. Put the fixed aluminum alloy pipes into the electron beam welding machine, and further fix them with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and position weld the aluminum alloy pipes through the holes reserved on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape. Set the positioning welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current 24A, high voltage 75kV, welding beam current 25mA, gun distance 150mm, single down-beam duration 1s, welding operation was performed on four positioning welding positions in sequence according to the same process parameters;

[0063] Step 7: Cleaning of aluminum alloy pipes. Take out the aluminum alloy pipes that have been positioned and welded from the welding chamber of the electron beam welder, tear off the high-temperature tape used for fixing, and then use ultrasonic cleaning to remove the glue and other impurities remaining on the surface of the pipes. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 70°C, and the cleaning time is 30 minutes. Then put the cleaned pipes into the oven for drying, the drying temperature is 80°C, and the drying time is 60 minutes;

[0064] Step 8: Formal welding of the welding gap of the aluminum alloy pipe. The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. Set the formal welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current is 24A, high voltage is 75kV, welding beam current is 25mA, side rotation chuck speed linear speed V is 1000mm / min, welding time is 12s, and gun distance is 150mm;

[0065] Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

[0066] Embodiment 4

[0067] A positioning welding method for an aluminum alloy pipe comprises the following steps:

[0068] Step 1: Preparation of aluminum alloy pipe and welding interface. The outer diameter of the pipe is 80mm, the wall thickness is 3mm, and the lengths of the two pipe sections are 250mm and 250mm respectively. Through wire cutting and sandpaper grinding, the welding interface can be docked. The widest part of the interface gap is X max The thickness is 0.18mm. After butt jointing, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe.

[0069] Step 2: Cleaning of aluminum alloy pipes: Remove oil stains and attached impurities on the surface of the pipes through ultrasonic cleaning. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 50°C, and the cleaning time is 30 minutes;

[0070] Step 3: Drying of aluminum alloy pipes: Place the cleaned aluminum alloy pipes in an oven for drying at a temperature of 80°C for 60 minutes.

[0071] Step 4: Preparation of high temperature tape. Prepare high temperature tape of appropriate length according to the size of aluminum alloy pipe. The width of high temperature tape is 100mm. Punch holes in the middle of the width of high temperature tape. The punching radius r is 2mm. The distance a between the center of the first hole and the starting point of the high temperature tape is 30mm. The distance b between the centers of subsequent punching holes from the first hole is 62.8mm. The reserved length Y of high temperature tape is 1400mm.

[0072] Step 5: Assembling and fixing the aluminum alloy pipe. Take out the cleaned and dried aluminum alloy pipe, align the two ends of the welding interface and make them as close as possible. The widest part of the interface gap is X max The diameter of the high-temperature tape is 0.18mm. Fix it with the high-temperature tape prepared in step 4. Align the middle of the width of the high-temperature tape with the welding gap. Wrap the aluminum alloy pipe 5 times and then cut off the excess tape and leave four evenly distributed holes. Each hole corresponds to a positioning welding position. The center of the punch hole reserved on the high-temperature tape is on the welding gap and the welding gap can be clearly seen through the hole position. The effective field of view radius of each hole is 2mm;

[0073] Step 6: Position welding of aluminum alloy pipes. Put the fixed aluminum alloy pipes into the electron beam welding machine, and further fix them with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and position weld the aluminum alloy pipes through the holes reserved on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape. Set the positioning welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current 24A, high voltage 70kV, welding beam current 15mA, gun distance 150mm, single down-beam beam duration 1s, welding operation was performed on four positioning welding positions in sequence according to the same process parameters;

[0074] Step 7: Cleaning of aluminum alloy pipes. Take out the aluminum alloy pipes that have been positioned and welded from the welding chamber of the electron beam welder, tear off the high-temperature tape used for fixing, and then use ultrasonic cleaning to remove the glue and other impurities remaining on the surface of the pipes. Ultrasonic cleaning uses 95% alcohol as the cleaning solution, the cleaning temperature is 70°C, and the cleaning time is 30 minutes. Then put the cleaned pipes into the oven for drying, the drying temperature is 80°C, and the drying time is 60 minutes;

[0075] Step 8: Formal welding of the welding gap of the aluminum alloy pipe. The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. Set the formal welding process parameters as follows: the vacuum degree of the gun chamber is 5×10 -3 Pa, the vacuum degree of welding chamber is 5×10 -3 Pa, filament current is 24A, high voltage is 70kV, welding beam current is 15mA, side rotation chuck speed linear speed V is 1000mm / min, welding time is 17s, and gun distance is 150mm;

[0076] Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

[0077] Generally, electron beam welding needs to be positioned by inert gas shielded welding before welding or the preparation is complex and can only meet the single-size tooling for positioning. Through the positioning welding scheme of the present invention, the risk of introducing impurities and forming defects in the conventional welding method of aluminum alloy during the positioning welding process can be effectively avoided. The same positioning welding method involves a flexible fixing method, which can meet the welding positioning requirements of aluminum alloy pipes of different sizes, without the need for customized tooling, low cost and simple operation. It can meet the needs of aluminum alloy pipes of different lengths, different diameters and different wall thicknesses through one-time welding. The weld is uniform and stable, and the heat-affected zone is small. It effectively avoids defects such as insufficient weld penetration, poor forming and slag inclusion bubbling during aluminum alloy welding. The welding process is carried out in a high vacuum environment without the participation of a protective atmosphere or the addition of additional welding materials. The introduction of impurities and the influence of the external environment are avoided during the welding process, which greatly improves the purity of the weld organization and the overall mechanical properties of the aluminum alloy pipe after welding. At the same time, the setting of digitized process parameters can greatly reduce the influence of human factors on the welding process, and can stably achieve the repetition of the process and the uniformity and stability of the welding results.

[0078] A method for positioning and welding aluminum alloy pipes, further comprising a winding device, the winding device being used to position two aluminum alloy pipes, punch holes in a high temperature tape, and wind the high temperature tape around the welding position of the two aluminum alloy pipes. The winding device comprises a machine base 1, on which two sets of rotating seats 2 are arranged, and the two sets of rotating seats 2 are respectively used to fix and position the two aluminum alloy pipes. After the rotating seats 2 fix the aluminum alloy pipes, the aluminum alloy pipes can rotate in the rotating seats 2.

[0079] A screw motor 4 is arranged on the front side of the machine base 1, which is driven by a screw motor 4 and connected to a screw 3. A screw slider 5 is arranged on the screw 3, which is connected to a driving seat 6. A rotating shaft 22 is connected to the driving seat 6, and a driving block 7 is connected to the rear end of the rotating shaft 22. A driving shaft 8 is rotatably arranged on the screw slider 5. A belt drive is adopted between the rotating shaft 22 and the driving shaft 8. A driving wheel 23 is connected to the rotating shaft 22, a transmission wheel 20 is connected to the driving shaft 8, and a transmission belt 21 is connected between the driving wheel 23 and the transmission wheel 20.

[0080] A conductor rod 9 is arranged at the rear side of the machine base 1, a slider 10 is slidably arranged on the conductor rod 9, a moving block 11 is connected to the slider 10, a rotating shaft 2 12 is rotatably connected to the front side of the moving block 11, a driving block 2 13 is connected to the front end of the rotating shaft 2 12, a driven shaft 14 is rotatably arranged at the front side of the slider 10, a belt drive is adopted between the driven shaft 14 and the rotating shaft 2 12, a transmission wheel 2 15 is connected to the driven shaft 14, a transmission wheel 3 16 is connected to the rotating shaft 2 12, and a transmission belt 2 17 is connected between the transmission wheel 2 15 and the transmission wheel 3 16.

[0081] The rear end of the driving shaft 8 is connected with a linkage shaft 18, a part of which is inserted into the driven shaft 14, and a plurality of limit strips 19 are arranged on the outer periphery of the linkage shaft 18, and a groove matching with the limit strips 19 is arranged on the inner wall of the driven shaft 14. The linkage shaft 18 on the driving shaft 8 can move along the axial direction of the driven shaft 14, so that the driving shaft 8 and the driven shaft 14 remain connected when they move, and at the same time, when the driving shaft 8 rotates, the driven shaft 14 can be driven to rotate synchronously through the linkage shaft 18.

[0082] Both the driving block 1 7 and the driving block 2 13 are truncated cone-shaped. The diameter of the end of the driving block 1 7 and the driving block 2 13 close to the aluminum alloy pipe is smaller than the diameter of the end away from the aluminum alloy pipe. This structural design allows the driving block 1 7 and the driving block 2 13 to be more conveniently inserted into the aluminum alloy pipe and against the inner wall of the aluminum alloy pipe, thereby driving the aluminum alloy pipe to rotate together.

[0083] The driving seat 6 includes a driven shaft 14, which is L-shaped. A rotating shaft 22 is rotatably arranged on the vertical section of the driven shaft 14. A transmission ball wheel 55 is connected to the front end of the rotating shaft 22. The transmission ball wheel 55 is provided with four semicircular grooves 56 and four driving grooves 57. The four semicircular grooves 56 and the four driving grooves 57 are evenly distributed on the transmission ball wheel 55, and the semicircular grooves 56 and the driving grooves 57 are staggered.

[0084] A driving shaft 50 is rotatably arranged on the horizontal section of the driven shaft 14, the upper end of the driving shaft 50 is connected to the hand wheel 49, the lower end of the driving shaft 50 is connected to the rotating disk 51, the lower part of the rotating disk 51 is connected to the driving arc plate 52, and the diameter of the driving arc plate 52 is the same as the diameter of the semicircular groove 56. The central angle of the driving arc plate 52 is 180 degrees. A connecting frame 53 is connected to the side of the rotating disk 51 opposite to the driving arc plate 52, and a driving rod 54 is connected to the connecting frame 53.

[0085] The winding device further includes an unwinding frame 58 and a guide seat 43 . The tape roll 59 is rotatably arranged on the unwinding frame 58 , and the tape on the tape roll 59 passes through the guide seat 43 .

[0086] A punching mechanism is provided below the guide seat 43, and the punching mechanism includes a base 24, a limit seat 39 is vertically provided on the base 24, a lifting plate 40 is provided below the guide seat 43, a spring 1 46 is provided on the upper part of the lifting plate 40, and a driving mechanism for driving the lifting plate 40 to move up and down is provided on the limit seat 39. A through hole is provided on the guide seat 43 at a position opposite to the spring 1 46.

[0087] A second spring 48 is connected to the upper portion of the base 24 , a buffer plate 47 is connected to the upper portion of the second spring 48 , and the buffer plate 47 is located below the lifting plate 40 .

[0088] The driving mechanism includes a connecting rod 41 connected to the lifting plate 40, the connecting rod 41 passes through the limiting seat 39, the connecting rod 41 can be lifted and lowered in the limiting seat 39, the end of the connecting rod 41 away from the lifting plate 40 is connected to the rack 42, the base 24 is provided with a rotating seat 36, the rotating seat 36 is coaxially provided with a driven bevel gear 38 and a half gear 37, the half gear 37 can mesh with the rack 42, the base 24 is rotatably provided with a driven shaft 2 34 and a driving shaft 2 32, the end of the driven shaft 2 34 away from the driving shaft 2 32 is connected to the driving bevel gear 35, the driving bevel gear 38 is coaxially provided with a driven bevel gear 38 and a half gear 37, the half gear 37 can mesh with the rack 42, the base 24 is rotatably provided with a driven shaft 2 34 and a driving shaft 2 32, the driven shaft 2 34 is connected to the driving bevel gear 35 at one end thereof. 5 is meshed with the driven bevel gear 38, the side of the driving shaft 2 32 close to the driven shaft 2 34 is connected with the linkage shaft 2 44, a part of the linkage shaft 2 44 is inserted into the driven shaft 2 34, a plurality of limit bars 2 45 are arranged on the outer periphery of the linkage shaft 2 44, the inner wall of the driven shaft 2 34 is arranged with a groove matched with the limit bars 2 45, a spring 1 46 is arranged on the outer sleeve of the limit bar 2 45, one end of the spring 1 46 is connected to the driven shaft 2 34, the other end of the spring 1 46 is connected to the driving shaft 2 32, and the end of the driving shaft 2 32 away from the driven shaft 2 34 is connected with the driven gear 33.

[0089] A moving seat 25 is slidably provided on the base 24, and the moving seat 25 is connected to the driven shaft 14 to move with the driven shaft 14. A rotating shaft 3 26 is rotatably provided on the moving seat 25, and a driving gear 30 is connected to the rear end of the rotating shaft 3 26, and a retaining ring 31 is provided on the rear side of the driving gear 30, and a driven gear 33 is meshed with the driving gear 30, and the front end of the driven gear 33 abuts against the rear end of the retaining ring 31. The diameter of the driving gear 30 is four times that of the driven gear 33. When the driving gear 30 rotates 90 degrees, the driven gear 33 rotates one circle, and the half gear 37 rotates one circle, so that when the pipeline rotates 90 degrees, the spring 1 46 of the punching mechanism rises and falls once, so that the punching frequency is consistent with the moving frequency of the high-temperature tape. Belt transmission is adopted between rotating shaft 1 22 and rotating shaft 3 26 , driving wheel 2 27 is connected to rotating shaft 1 22 , transmission wheel 4 28 is connected to rotating shaft 3 26 , and transmission belt 3 29 is connected between driving wheel 27 and transmission wheel 4 28 .

[0090] Two aluminum alloy pipes are placed on two sets of rotating seats 2 respectively, and the aluminum alloy pipes are fixed and positioned by the two sets of rotating seats 2 so that the two ends of the welding interface are aligned and as close as possible, and the widest part of the interface gap is ≤0.2mm.

[0091] The screw motor 4 drives the screw 3 to rotate to drive the screw slider 5 to move, so that the driving block 1 7 is inserted into the front end of the aluminum alloy pipe on the front side. Then the moving block 11 is moved to insert the driving block 2 13 into the rear end of the aluminum alloy pipe on the rear side. The driving seat 6 drives the rotating shaft 1 22 to rotate, which can drive the driving block 1 7 and the driving block 2 13 to rotate together, thereby driving the two aluminum alloy pipes to rotate synchronously.

[0092] The hand wheel 49 is turned, and the hand wheel 49 drives the rotating disk 51 to rotate through the driving shaft 50, and the rotating disk 51 drives the driving arc plate 52 and the connecting frame 53 to rotate. After the driving rod 54 on the connecting frame 53 rotates, it can enter the driving groove 57. The driving rod 54 acts on the driving groove 57 to drive the transmission ball wheel 55 to rotate. After the transmission ball wheel 55 rotates 90 degrees, the driving rod 54 disengages from the driving groove 57, and the driving arc plate 52 enters the semicircular groove 56. When the rotating disk 51 rotates later, the driving arc plate 52 rotates in the semicircular groove 56, so that the transmission ball wheel 55 remains stationary. This coordination makes the transmission ball wheel 55 stationary for a certain period of time after each rotation of 90 degrees, which also makes the aluminum alloy pipe stationary for a certain period of time after each rotation of 90 degrees by the driving block 7.

[0093] Align the middle of the high-temperature tape width with the center of the width of the gap between the two aluminum alloy pipes, and then stick the high-temperature tape to the aluminum alloy pipe. Pull the high-temperature tape to move by rotating the aluminum alloy pipe. Since the aluminum alloy pipe rotates 90 degrees each time, the tape only moves 0.25πD each time, thus ensuring that the distance between the centers of the holes punched each time is 0.25πD. At the same time, since the aluminum alloy pipe will stop for a certain period of time after each 90-degree rotation, the tape will also stop after each movement, which leaves enough time for the punching mechanism to punch holes.

[0094] Before wrapping the tape around once, cut off the excess portion between the first hole and the end of the high-temperature tape so that the distance between the first hole and the end of the high-temperature tape is greater than r and less than 0.25πD-r, to avoid the length between the first hole and the end of the high-temperature tape being too long and blocking the hole.

[0095] When the driven shaft 14 moves, it drives the moving seat 25 to move synchronously, so that the belt transmission can be maintained between the rotating shaft 1 22 and the rotating shaft 3 26. When the rotating shaft 3 26 drives the driving gear 30 to rotate, the driving shaft 2 32 is driven to rotate by the cooperation of the driving gear 30 and the driven gear 33. The driving shaft 2 32 then drives the driven shaft 2 34 to rotate through the linkage shaft 2 44, and the driven shaft 2 34 drives the half gear 37 to rotate through the cooperation of the driving bevel gear 35 and the driven bevel gear 38. Due to the structure of the half gear 37, when the toothed part of the half gear 37 is engaged with the rack 42, it can drive the rack 42 to move upward, and the rack 42 then drives the lifting plate 40 to rise through the connecting rod 41, thereby driving the spring 1 46 on the lifting plate 40 to rise to complete the punching of the tape. When the toothless part of the half gear 37 rotates to the position of the rack 42, the two are no longer engaged, and the lifting plate 40 descends under the action of gravity, so that the rack 42 returns to its original position. The second spring 48 and the buffer plate 47 are provided to support the descending lifting plate 40 and play a buffering role.

[0096] A spring 1 46 is provided between the driven shaft 2 34 and the driving shaft 2 32. Since the driving bevel gear 35 is meshed with the driven bevel gear 38, the position of the driven shaft 2 34 is relatively fixed, and the spring 1 46 has an elastic force to push the driving shaft 2 32 away from the driven shaft 2 34. When the moving seat 25 drives the driving gear 30 to move, under the action of the spring 1 46, the driven gear 33 can always resist the retaining ring 31, thereby ensuring that the driven gear 33 and the driving gear 30 remain meshed.

[0097] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A positioning welding method for an aluminum alloy pipe, characterized in that: The following steps are involved: Step 1: Prepare two aluminum alloy pipes with an outer diameter of D. Use wire cutting and sandpaper grinding to make the welding interface dockable. The widest part of the interface gap is ≤0.2mm. After docking, the aluminum alloy pipe is straight as a whole, and the plane where the welding gap is located is perpendicular to the length direction of the pipe. Step 2: Use ultrasonic cleaning to remove oil stains and attached impurities on the surface of the pipe; Step 3: Place the cleaned aluminum alloy pipe in an oven for drying; Step 4: Punch holes at intervals in the middle of the width of the high-temperature tape. The punch radius r is 2mm-3mm. The distance between the center of the first hole and the starting point of the high-temperature tape is greater than r and less than 0.25πD-r. The distance between the punch centers is 0.25πD. The reserved length of the high-temperature tape should be enough to wrap around the aluminum alloy pipe for more than 5 turns. Step 5: Take out the aluminum alloy pipe dried in step 3, align and close the two ends of the welding interface, and the widest part of the interface gap is ≤0.2mm. Fix it with high-temperature tape, align the middle of the high-temperature tape width with the welding gap, wrap it for more than 5 circles, and leave four evenly distributed holes, each hole corresponds to a positioning welding position; Step 6: Put the fixed aluminum alloy pipe into the electron beam welding machine, and further fix it with the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding room, and perform positioning welding on the aluminum alloy pipe through the reserved holes on the high-temperature tape. Adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor, so that the electron beam can bombard the welding gap on the aluminum alloy pipe through the holes on the high-temperature tape, and perform welding operations on the four positioning welding positions in turn according to the same process parameters; Step 7: Take out the aluminum alloy pipe after positioning welding from the welding chamber of the electron beam welder, tear off the high-temperature tape originally used for fixing, and then use ultrasonic cleaning to remove the impurities such as glue remaining on the surface of the pipe; put the cleaned pipe into the oven for drying; Step 8: The aluminum alloy pipe cleaned and dried in step 7 is further fixed by the side rotating chuck and ejector in the electron beam welding machine. After clamping, close the door of the welding chamber, and adjust the position of the electron beam gun and the workpiece by rotating the measuring chuck and the gun moving motor so that the electron beam flow from the electron beam gun can bombard the welding gap position on the aluminum alloy pipe. The formal welding process parameters are set as follows: gun chamber vacuum degree ≤5×10 -3 Pa, vacuum degree of welding chamber ≤5×10 -3 Pa, filament current is 22A-24A, high voltage is 68kV-80kV, welding beam current is 4mA-6mA per mm of pipe wall thickness, side-rotating chuck speed V is 1000mm / min-1500mm / min, welding time is greater than πD / V, and gun distance is 150mm-200mm; Step 9: After welding, take the welded aluminum alloy pipe out of the welding chamber of the electron beam welder.

2. The positioning welding method of an aluminum alloy pipe according to claim 1 is characterized in that: In step 2, ultrasonic cleaning uses alcohol with a concentration of ≥95% as a cleaning solution, the cleaning temperature is 30°C-50°C, and the cleaning time is ≥30min.

3. The positioning welding method of an aluminum alloy pipe according to claim 1 is characterized in that: In step 3, the drying temperature is 80°C-100°C, and the drying time is ≥60min.

4. The positioning welding method of an aluminum alloy pipe according to claim 1 is characterized in that: In step 5, the center of the hole on the high temperature tape is on the welding gap and the welding gap can be clearly seen through the hole, and the effective field of view radius of each hole is ≥ 2mm.

5. The positioning welding method of an aluminum alloy pipe according to claim 1 is characterized in that: In step 6, the positioning welding process parameters are set as follows: gun chamber vacuum degree ≤ 5×10 -3 Pa, vacuum degree of welding chamber ≤5×10 -3 Pa, filament current is 22A-24A, high voltage is 68-80kV, welding beam current is 4mA-6mA for every millimeter of pipe wall thickness, gun distance is 150mm-200mm, and single beam duration is 1s.

6. The positioning welding method of an aluminum alloy pipe according to claim 1, characterized in that: In step seven, ultrasonic cleaning uses alcohol with a concentration of ≥95% as a cleaning solution, the cleaning temperature is 50°C-70°C, and the cleaning time is ≥30min.

7. A positioning welding method for an aluminum alloy pipe according to claim 6, characterized in that: In step seven, the drying temperature is 80°C-100°C, and the drying time is ≥60min.

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