A laser additive-welding device and method for dissimilar materials based on gradual transition

Abstract

The present invention discloses a dissimilar material laser additive-welding device and method based on gradual transition, belonging to the field of laser additive welding technology. The dissimilar material laser additive-welding device based on gradual transition is provided with a fixing mechanism and an additive welding mechanism above the workbench, a multi-source laser welding head is provided on the mounting plate of the additive welding mechanism, and a plurality of powder feeding tubes are provided on both sides of the multi-source laser welding head. The powder feeding tube contains a mixed powder containing two dissimilar material alloy elements, and the proportion of the base material powder in the mixed powder decreases gradually from one end close to the base material material to the other end; a height adjustment structure for adjusting the height of the multi-source laser welding head is provided on the mounting plate. The dissimilar material laser additive-welding device and method based on gradual transition described in the present invention can solve the existing problems of low connection efficiency and insufficient joint strength of dissimilar metal materials, and improve the welding quality of dissimilar thin-walled metals.

Description

Technical Field

[0001] The present invention relates to the technical field of laser additive welding, and in particular to a dissimilar material laser additive welding device and method based on gradual transition. Background Art

[0002] Laser additive manufacturing technology, also known as laser 3D printing technology, is a laser manufacturing technology that uses computer-aided processing to slice three-dimensional solid models into two-dimensional layers, which are then discretized into one-dimensional lines, and then deposited point by point using laser cladding technology to finally achieve the formation of three-dimensional solid parts. Compared with traditional manufacturing technology, this technology has the characteristics of flexibility, easy to realize intelligentization, short production cycle, high precision of parts, and good mechanical properties. This technology has been widely used in aviation, national defense, transportation, energy, metallurgy, mining and other fields.

[0003] In the field of aerospace, titanium alloys, aluminum alloys and other light alloys are widely used in large-sized thin-walled structures, and dissimilar metals need to be connected. Welding is generally used to connect dissimilar metals, but the traditional "forming-machining-welding" method cannot meet the needs of connecting thin-walled dissimilar metals. Laser welding-additive technology combines the advantages of laser selective melting (SLM), laser metal deposition (LMD) and laser welding, which can effectively improve the structural processing accuracy and designability, reduce stress concentration and fatigue weak areas, and provide a new solution for weight reduction, life increase, low cost and rapid manufacturing of light alloy special-shaped complex structures.

[0004] The existing patent CN201910198142.6 discloses a method for connecting dissimilar metal materials by combining laser additive and laser welding. It can convert dissimilar metal welding into homogeneous metal welding by adding a transition metal plate with a gradient change in the element, effectively solving the problem of difficult welding caused by the large difference in melting points of dissimilar metals, avoiding the generation of brittle metal compound phases during dissimilar metal welding, and at the same time, by directly adding transition metal with a high melting point metal as the substrate, reducing the number of welding times when using transition metal welding, avoiding the introduction of unnecessary residual stress, and effectively improving the service life of dissimilar metal welded parts. The above patent first needs to print the first layer on the surface of the high melting point metal substrate, and then change the powder feeding ratio to print the second layer, and then proceed in sequence until the connection of the dissimilar metal materials is completed. The above patent requires multiple passes of printing to complete the connection of dissimilar metal materials, which affects the connection efficiency of dissimilar metal materials. Summary of the invention

[0005] The purpose of the present invention is to provide a dissimilar material laser additive-welding device and method based on gradual transition, so as to solve the problem of low efficiency of existing dissimilar metal material connection.

[0006] To achieve the above-mentioned purpose, the present invention provides a dissimilar material laser additive-welding device based on gradual transition, comprising a workbench, a fixing mechanism for fixing a workpiece is arranged above the workbench, an additive welding mechanism is arranged above the workbench, the additive welding mechanism is located between two fixing mechanisms, and the additive welding mechanism is arranged on a robotic arm; the additive welding mechanism comprises a mounting plate, a multi-source laser welding head is arranged on the mounting plate, a plurality of powder feeding pipes are symmetrically arranged on both sides of the multi-source laser welding head, the powder feeding pipe contains a mixed powder containing alloy elements of two dissimilar materials, and the proportion of base material powder in the mixed powder decreases gradually from one end close to the base material to the other end; a height adjustment structure for adjusting the height of the multi-source laser welding head is arranged on the mounting plate, and the height adjustment structure is connected to the powder feeding pipe through an angle adjustment structure.

[0007] Preferably, the multi-source laser welding head comprises a semiconductor laser and a blue light laser, the wavelength of the semiconductor laser is greater than that of the blue light laser; the wavelength of the semiconductor laser is 915 nm, and the wavelength of the blue light laser is 450 nm.

[0008] Preferably, mounting seats are rotatably provided at both ends of the mounting plate, an air supply pipe is provided on the mounting seat, the air supply pipe is connected to an external inert gas bottle, a turntable is provided on the mounting seat, and a locking wire is provided on the turntable to lock the turntable and the mounting plate.

[0009] Preferably, the powder feeding tube includes a first powder feeding tube, a second powder feeding tube, a third powder feeding tube and a fourth powder feeding tube which are arranged in sequence, and the top ends of the first powder feeding tube, the second powder feeding tube, the third powder feeding tube and the fourth powder feeding tube are hinged to the mounting plate, and the first powder feeding tube, the second powder feeding tube, the third powder feeding tube and the fourth powder feeding tube respectively form a first powder spreading point, a second powder spreading point, a third powder spreading point and a fourth powder spreading point on the horizontal plane where the upper surface of the workpiece is located, and the first powder spreading point, the second powder spreading point, the third powder spreading point and the fourth powder spreading point are located in a semiconductor laser spot formed by a semiconductor laser on the upper surface of the workpiece, and the semiconductor laser spot covers the upper surface of the workpiece, and a blue light laser forms a blue light laser spot on the upper surface of the workpiece, and the blue light laser spot covers the first powder spreading point and the fourth powder spreading point, and the second powder spreading point and the third powder spreading point are located in the blue light laser spot; the distance between adjacent powder spreading points of the first powder spreading point, the second powder spreading point, the third powder spreading point and the fourth powder spreading point is not greater than 0.05 mm.

[0010] Preferably, the height adjustment structure includes a lifting plate, the multi-source laser welding head is fixedly arranged on the lifting plate, a first screw rod is rotatably arranged on the mounting plate, a threaded hole is arranged on the lifting plate for the first screw rod to pass through and is adapted to the first screw rod, a motor or a knob is arranged on the top of the first screw rod to drive the first screw rod to rotate, a slide rail is arranged on the mounting plate for guiding the lifting and lowering of the lifting plate, a slide groove adapted to the slide rail is arranged on the lifting plate, and the slide rail is located in the slide groove and is slidably connected to the slide groove.

[0011] Preferably, the angle adjustment structure includes connecting rods, which are arranged on both sides of the lifting plate, one end of the two connecting rods are hinged to the two end heads of the lifting plate respectively, the other end of one connecting rod is hinged to the second powder delivery pipe, and the other end of the other connecting rod is hinged to the third powder delivery pipe; an arc-shaped first limiting groove that guides the rotation of the second powder delivery pipe and the third powder delivery pipe is provided on the mounting plate; the second powder delivery pipe and the first powder delivery pipe, and the third powder delivery pipe and the fourth powder delivery pipe are all connected through a connecting structure, and an arc-shaped second limiting groove that guides the rotation of the first powder delivery pipe and the fourth powder delivery pipe is provided on the mounting plate.

[0012] Preferably, the connecting structure includes a sleeve and a connecting plate, a first limit rod is rotatably provided at one end of the connecting plate, the first limit rod is located in the second limit groove, the first limit rod is connected to the first powder feeding pipe or the fourth powder feeding pipe, a second limit rod is rotatably provided at one end of the sleeve, the second limit rod is located in the first limit groove, the second limit rod is connected to the second powder feeding pipe or the third powder feeding pipe, one end of the connecting plate is inserted in the sleeve and slidably connected with the sleeve, a transmission gear is rotatably provided below the sleeve, an opening is provided on the side wall of the sleeve for inserting the transmission gear into the sleeve, a rack is provided at the bottom of the transmission gear and meshing with the connecting plate, a transmission rack is provided below the transmission gear, a first fixed plate is provided below the transmission rack, the first fixed plate is fixedly provided on the mounting plate, a vertical support rod is provided on the transmission rack, a through hole is provided on the first fixed plate for the support rod to pass through, the support rod is slidably connected to the first fixed plate, a first spring is provided between the transmission rack and the first fixed plate, and the transmission rack is always meshed with the transmission gear under the action of the first spring.

[0013] Preferably, the workbench includes a support plate, the workpiece is placed on the support plate, the support plate is provided with an avoidance groove, and the connecting ends of the two workpieces are located directly above the avoidance groove; positioning structures for positioning the two workpieces are respectively provided on both sides of the avoidance groove, and the positioning structure includes a second fixed plate and a movable plate which are relatively arranged, the second fixed plate is fixedly arranged on the support plate, a horizontal guide rod is arranged at one end of the movable plate away from the second fixed plate, a guide hole for the guide rod to pass through is arranged on the side of the support plate, the guide rod is slidably connected to the support plate, a second spring is arranged between the movable plate and the side, and a guide groove which guides the horizontal sliding of the movable plate is arranged on the support plate.

[0014] Preferably, the fixing mechanism includes a top plate, the top plate is located above the support plate and fixedly connected to the support plate, a pressure plate is provided below the top plate, a vertical sliding rod is provided on the pressure plate, a sliding hole is provided on the top plate for the sliding rod to pass through, the top plate and the sliding rod are slidably connected, and the pressure plate is located between the second fixed plate and the movable plate; a transmission rod is provided between the top plate and the pressure plate, the two ends of the transmission rod are respectively hinged with a first connecting rod, the other end of the first connecting rod is hinged with a second connecting rod and a third connecting rod, the other end of the second connecting rod is hinged to the top plate, the other end of the third connecting rod is hinged to the pressure plate, a second screw rod is provided on the top plate to drive the transmission rod to move up and down, the bottom end of the second screw rod is rotatably connected to the transmission rod, the second screw rod is threadedly connected to the top plate, and the top end of the second screw rod is provided with a handle to drive the second screw rod to rotate.

[0015] The laser additive-welding method based on the above-mentioned dissimilar material laser additive-welding device based on gradual transition comprises the following steps:

[0016] S1. Place the workpieces to be welded on the support plate, adjust the distance between the workpieces to be welded, and the movable plate presses the workpieces tightly between the movable plate and the second fixed plate under the action of the second spring;

[0017] S2, rotating the second screw rod, the second screw rod drives the transmission rod to move downward, the transmission rod drives the pressing plate to move downward through the first connecting rod, the second connecting rod and the third connecting rod, the pressing plate is pressed against the upper surface of the workpiece to fix the workpiece;

[0018] S3, the robot arm drives the mounting plate to move to the connection of the workpieces to be welded, and adjusts the position of the multi-source laser welding head so that the multi-source laser welding head is located directly above the connection of the workpieces to be welded;

[0019] S4, rotate the first screw rod, the first screw rod drives the lifting plate to move up and down, the lifting plate drives the multi-source laser welding head to move up and down synchronously, the lifting plate drives the second powder feeding tube and the third powder feeding tube to rotate through the connecting rod, adjust the angle of the second powder feeding tube and the third powder feeding tube, the second powder feeding tube and the third powder feeding tube drive the sleeve to move through the second limiting rod, the sleeve drives the connecting plate to move synchronously through the transmission gear and the rack, the transmission gear rotates under the action of the transmission rack during the movement, the transmission gear drives the connecting plate to slide in the sleeve through the rack, thereby adjusting the angle of the first powder feeding tube and the fourth powder feeding tube, so that the distance between adjacent powder spreading points is not more than 0.05mm, the blue light laser spot covers the first powder spreading point and the fourth powder spreading point, and the semiconductor laser spot covers the upper surface of the workpiece;

[0020] S5. Start the semiconductor laser and the blue light laser, start the powder feeder, and the robot arm drives the multi-source laser welding head and the powder feeder to move along the connection of the workpieces to be welded through the mounting plate to weld the workpieces to be welded.

[0021] The advantages and positive effects of the dissimilar material laser additive-welding device and method based on gradual transition described in the present invention are:

[0022] 1. The present invention is provided with multiple powder delivery pipes, and the mixed powder components in the powder delivery pipes are distributed in a stepped manner according to the components of the base material, so as to realize a stepped transition connection between dissimilar metals, which is beneficial to improving the welding quality of dissimilar metals. Multiple powder delivery pipes deliver powder synchronously, and the welding between dissimilar metals is realized in one pass, which improves the welding efficiency.

[0023] 2. The present invention adopts a multi-source laser welding head, which heats the powder and the workpiece through a semiconductor laser to improve the metallurgical bonding effect between the weld and the workpiece; and centrally heats the powder through a blue light laser to promote the melting of the powder, which is beneficial to improving the welding efficiency.

[0024] 3. The multi-source laser welding head can be adjusted in height through the first screw rod to meet the welding needs of different reserved spacing. The powder feeding tube is adjusted in angle through the connecting rod, and the second powder feeding tube and the first powder feeding tube, and the third powder feeding tube and the fourth powder feeding tube are adjusted through the transmission gear and rack, so as to achieve the synchronous angle adjustment between the first powder feeding tube, the second powder feeding tube, the third powder feeding tube, and the fourth powder feeding tube, and then adjust the distance between the powder spreading points, so that the powder can fully fill the weld and can be fully melted and combined to improve the quality of the weld.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0027] Figure 2 It is a schematic structural diagram of an additive welding mechanism according to an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the back structure of the additive welding mechanism according to an embodiment of the present invention;

[0029] Figure 4 For attachment Figure 3 Middle A: Enlarged view;

[0030] Figure 5 A schematic diagram of the workbench structure of an embodiment of the present invention;

[0031] Figure 6 It is a schematic diagram of the fixing mechanism structure of an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of the structure of a multi-source laser welding head according to an embodiment of the present invention;

[0033] Figure 8Schematic diagram of the laser spot structure according to an embodiment of the present invention.

[0034] Reference numerals

[0035] 1. Additive welding mechanism; 11. Mounting plate; 12. Multi-source laser welding head; 13. First powder feeding pipe; 14. Second powder feeding pipe; 15. Third powder feeding pipe; 16. Fourth powder feeding pipe; 17. Lifting plate; 18. Slide rail; 19. First screw rod; 110. Connecting rod; 111. Connecting seat; 112. First limiting groove; 113. Mounting seat; 114. Air feeding pipe; 115. Turntable; 116. Locking wire; 117. First limiting rod; 1 18. Connecting plate; 119. Second limiting rod; 120. Sleeve; 121. Transmission gear; 122. Transmission rack; 123. First fixing plate; 124. Support rod; 125. First spring; 126. Semiconductor laser; 127. Blue laser; 128. Semiconductor laser spot; 129. Blue laser spot; 130. First powdering point; 131. Second powdering point; 132. Third powdering point; 133. Fourth powdering point;

[0036] 2. Workbench; 21. Support plate; 22. Avoidance groove; 23. Second fixed plate; 24. Movable plate; 25. Guide groove; 26. Guide rod; 27. Second spring;

[0037] 3. Fixing mechanism; 31. Top plate; 32. Pressing plate; 33. Second screw rod; 34. Transmission rod; 35. First connecting rod; 36. Second connecting rod; 37. Third connecting rod; 38. Sliding rod; DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0039] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalent elements or objects, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0040] like Figure 1As shown. A dissimilar material laser additive-welding device based on gradual transition includes a workbench 2, and the workbench 2 is used to place a workpiece. A fixing mechanism 3 for fixing the workpiece is arranged above the workbench 2, and the workpiece is fixed to the workbench 2 by the fixing mechanism 3, so as to avoid displacement of the workpiece during welding, which is beneficial to improving the welding quality of the workpiece. An additive welding mechanism is arranged above the workbench 2, and the additive welding mechanism 1 is located between the two fixing mechanisms 3. The additive welding mechanism 1 is used to weld two workpieces. The additive welding mechanism 1 is arranged on a robotic arm, and the robotic arm adopts an existing structure. The additive welding mechanism 1 is driven to move by the robotic arm, so as to adjust the position of the additive welding mechanism 1 and complete the welding.

[0041] like Figure 2 As shown. The additive welding mechanism 1 includes a mounting plate 11, on which a multi-source laser welding head 12 is arranged. The mounting plate 11 is provided with a height adjustment structure for adjusting the height of the multi-source laser welding head 12. The height adjustment structure includes a lifting plate 17, and the lifting plate 17 is located on one side of the mounting plate 11, and the multi-source laser welding head 12 is fixedly arranged on the lifting plate 17. A first screw rod 19 is rotatably arranged on the mounting plate 11 through a bearing, and a threaded hole is provided on the lifting plate 17 for the first screw rod 19 to pass through and is adapted to the first screw rod 19. A motor or a knob for driving the first screw rod 19 to rotate is provided at the top of the first screw rod 19. A slide rail 18 that has a guiding effect on the lifting and lowering of the lifting plate 17 is fixedly arranged on the mounting plate 11, and a slide groove adapted to the slide rail 18 is fixedly arranged on the lifting plate 17, and the slide rail 18 is located in the slide groove and is slidably connected to the slide groove. The first screw rod 19 is driven to rotate by a motor or a knob, and the first screw rod 19 is threadedly engaged with the lifting plate 17 to drive the lifting plate 17 to move up and down, thereby driving the multi-source laser welding head 12 to move up and down, and adjusting the size of the light spot on the upper surface of the workpiece to meet the welding needs of different reserved gaps.

[0042] A plurality of powder feeding tubes are symmetrically arranged on both sides of the multi-source laser welding head 12, and the powder feeding tubes contain a mixed powder including two different material base material powders. The proportion of base material powder in the mixed powder decreases gradually from one end close to the base material to the other end, that is, a progressive powder feeding with a step-shaped change in the composition of the mixed powder is realized, and a gradual transition of the composition between the two different materials is realized to reduce the problem of low welding quality caused by a large difference in composition or a large difference in melting point.

[0043] In this embodiment, the powder delivery pipe includes a first powder delivery pipe 13, a second powder delivery pipe 14, a third powder delivery pipe 15 and a fourth powder delivery pipe 16 which are arranged in sequence. The tops of the first powder delivery pipe 13, the second powder delivery pipe 14, the third powder delivery pipe 15 and the fourth powder delivery pipe 16 are fixedly provided with a connecting seat 111, and the connecting seat is hinged to the mounting plate 11. The interiors of the first powder delivery pipe 13, the second powder delivery pipe 14, the third powder delivery pipe 15 and the fourth powder delivery pipe 16 are powder delivery channels with round holes, and the powder delivery channels are connected to the powder feeder through the powder delivery pipes. The powder feeder adopts the existing structure as needed. The lifting plate 17 is connected to the second powder delivery pipe 14 and the third powder delivery pipe 15 through an angle adjustment structure. The angle adjustment structure includes a connecting rod 110, and the connecting rod 110 is arranged on both sides of the lifting plate 17. One end of the two connecting rods 110 is hinged to the two ends of the lifting plate 17 respectively, the other end of one connecting rod 110 is hinged to the second powder delivery pipe 14, and the other end of the other connecting rod 110 is hinged to the third powder delivery pipe 15. The lifting plate 17 drives the second powder delivery pipe 14 and the third powder delivery pipe 15 to rotate through the connecting rod 110 to adjust the angle between the second powder delivery pipe 14 and the third powder delivery pipe 15. The mounting plate 11 is provided with an arc-shaped first limiting groove 112 that has a guiding effect on the rotation of the second powder delivery pipe 14 and the third powder delivery pipe 15, and the center of the first limiting groove 112 coincides with the hinge point of the second powder delivery pipe 14, the third powder delivery pipe 15 and the mounting plate 11. The mounting plate 11 is provided with an arc-shaped second limiting groove that has a guiding effect on the rotation of the first powder delivery pipe 13 and the fourth powder delivery pipe 16.

[0044] like Figure 3 , Figure 4 As shown. The second powder delivery pipe 14 is connected to the first powder delivery pipe 13, and the third powder delivery pipe 15 is connected to the fourth powder delivery pipe 16 by a connecting structure. The connecting structure includes a sleeve 120 and a connecting plate 118, and a first limiting rod 117 is rotatably provided at one end of the connecting plate 118, and the first limiting rod 117 is located in the second limiting groove, and the first limiting rod 117 slides in the second limiting groove. The first limiting rod 117 is fixedly connected to the first powder delivery pipe 13 or the fourth powder delivery pipe 16. A second limiting rod 119 is rotatably provided at one end of the sleeve 120, and the second limiting rod 119 is located in the first limiting groove 112, and the second limiting rod 119 slides in the first limiting groove 112. The second limiting rod 119 is connected to the second powder delivery pipe 14 or the third powder delivery pipe 15. One end of the connecting plate 118 is inserted in the sleeve 120 and is slidably connected to the sleeve 120, and only horizontal sliding occurs between the sleeve 120 and the connecting plate 118.

[0045] A transmission gear 121 is arranged below the sleeve 120. The transmission gear 121 is rotatably arranged on a plate through a bearing, and the plate is fixed on the sleeve 120. The sleeve 120 drives the transmission gear 121 to move synchronously through the plate. An opening is arranged on the side wall of the sleeve 120 for the transmission gear 121 to be inserted into the sleeve 120, and a rack is fixedly arranged at the bottom of the connecting plate 118 for the transmission gear 121 to mesh with. A transmission rack 122 is arranged below the transmission gear 121, and a first fixed plate 123 is arranged below the transmission rack 122. The first fixed plate 123 is fixedly arranged on the mounting plate 11. A vertical support rod 124 is fixedly arranged on the transmission rack 122, and a through hole is arranged on the first fixed plate 123 for the support rod 124 to pass through. The support rod 124 is slidably connected to the first fixed plate 123. A first spring 125 is arranged between the transmission rack 122 and the first fixed plate 123. The two ends of the first spring 125 are respectively fixed on the transmission rack 122 and the first fixed plate 123. The first spring 125 is sleeved on the outside of the support rod 124. Under the action of the first spring 125, the transmission rack 122 is always meshed with the transmission gear 121.

[0046] The second powder delivery pipe 14 and the third powder delivery pipe 15 drive the first powder delivery pipe 13 and the fourth powder delivery pipe 16 to rotate synchronously through the sleeve 120 and the connecting plate 118 respectively. At the same time, the transmission gear 121 rotates under the action of the transmission rack 122. The rotation of the transmission gear 121 drives the connecting plate 118 to slide through the rack, and the first powder delivery pipe 13 and the fourth powder delivery pipe 16 are further adjusted in angle, so that the angle adjustment of the first powder delivery pipe 13 and the fourth powder delivery pipe 16 is greater than the angle adjustment of the second powder delivery pipe 14 and the third powder delivery pipe 15, so as to ensure the distance between the powder outlet ends of the first powder delivery pipe 13, the second powder delivery pipe 14, the third powder delivery pipe 15 and the fourth powder delivery pipe 16.

[0047] A cover shell may be provided outside the mounting plate 11 to enclose the powder delivery pipe and the multi-source laser welding head 12 inside.

[0048] like Figure 7 , Figure 8As shown. The multi-source laser welding head 12 includes a semiconductor laser 126 and a blue laser 127, and the wavelength of the semiconductor laser 126 is greater than the wavelength of the blue laser 127. In this embodiment, the wavelength of the semiconductor laser 126 is 915nm, and the wavelength of the blue laser 127 is 450nm. The semiconductor laser spot 128 is coaxial with the blue laser spot 129. The first powder feeding tube 13, the second powder feeding tube 14, the third powder feeding tube 15 and the fourth powder feeding tube 16 respectively form a first powder spreading point 130, a second powder spreading point 131, a third powder spreading point 132 and a fourth powder spreading point 133 on the horizontal plane where the upper surface of the workpiece is located. The first powder spreading point 130, the second powder spreading point 131, the third powder spreading point 132 and the fourth powder spreading point 133 are located in the semiconductor laser spot 128 formed by the semiconductor laser 126 on the upper surface of the workpiece, and the semiconductor laser spot 128 covers the upper surface of the workpiece. The semiconductor laser melts the powder and heats the end of the workpiece to be welded, so that the powder and the workpiece can be fully fused together, thereby improving the quality of welding. The blue laser 127 forms a blue laser spot 129 on the upper surface of the workpiece, and the blue laser spot 129 covers the first powder-spreading point 130 and the fourth powder-spreading point 133. The second powder-spreading point 131 and the third powder-spreading point 132 are located within the blue laser spot 129. The blue laser heats the powder in a concentrated manner, so that the powder melts quickly and fully, which is beneficial to improving welding efficiency. The distance between adjacent powder-spreading points of the first powder-spreading point 130, the second powder-spreading point 131, the third powder-spreading point 132 and the fourth powder-spreading point 133 is not greater than 0.05 mm to ensure that the powder is effectively filled in the weld and improve the quality of welding.

[0049] The mounting plate 11 has mounting seats 113 rotatably disposed at both ends through bearings. The mounting seats 113 are provided with through holes, and the air supply pipe 114 is inserted into the through holes. The mounting seats 113 are provided with a top screw for locking the air supply pipe 114. The air supply pipe 114 is connected to an external inert gas bottle for providing inert protective gas. A turntable 115 is fixedly disposed on the mounting seat 113, and a locking screw 116 is provided on the turntable 115 for locking the turntable 115 and the mounting plate 11.

[0050] like Figure 5As shown. The workbench 2 includes a support plate 21, and the workpiece is placed on the support plate 21. The support plate 21 is provided with an avoidance groove 22, and the connecting ends of the two workpieces are located directly above the avoidance groove 22. Positioning structures for positioning the two workpieces are respectively provided on both sides of the avoidance groove 22. The positioning structure includes a second fixed plate 23 and a movable plate 24 arranged opposite to each other, and the second fixed plate 23 is fixedly arranged on the support plate 21. A horizontal guide rod 26 is fixedly arranged at one end of the movable plate 24 away from the second fixed plate 23, and a guide hole for the guide rod 26 to pass through is arranged on the side of the support plate 21, and the guide rod 26 is slidably connected to the support plate 21. A second spring 27 is arranged between the movable plate 24 and the side, and the two ends of the second spring 27 are respectively fixedly connected to the movable plate 24 and the side, and the second spring 27 is sleeved on the guide rod 26. A guide groove 25 having a guiding effect on the horizontal sliding of the movable plate 24 is provided on the support plate 21. The tops of the opposite sides of the movable plate 24 and the second fixed plate 23 are provided with inclined surfaces, so that the workpiece can be placed between the second fixed plate 23 and the movable plate 24. The movable plate 24 presses the workpiece tightly between the movable plate 24 and the second fixed plate 23 under the action of the second spring 27.

[0051] like Figure 6 As shown. The fixing mechanism 3 includes a top plate 31, which is located above the support plate 21 and fixedly connected to the support plate 21. A pressing plate 32 is provided below the top plate 31, and the pressing plate 32 is located between the second fixed plate 23 and the movable plate 24. The pressing plate 32 presses on the upper surface of the workpiece to press the workpiece. A vertical sliding rod 38 is fixedly provided on the pressing plate 32, and a sliding hole for the sliding rod 38 to pass through is provided on the top plate 31, and the top plate 31 is slidably connected to the sliding rod 38. A transmission rod 34 is provided between the top plate 31 and the pressing plate 32, and the two ends of the transmission rod 34 are respectively hinged with a first connecting rod 35, and the other end of the first connecting rod 35 is hinged with a second connecting rod 36 and a third connecting rod 37, the other end of the second connecting rod 36 is hinged to the top plate 31, and the other end of the third connecting rod 37 is hinged to the pressing plate 32. The top plate 31 is provided with a second screw rod 33 for driving the transmission rod 34 to move up and down, the bottom end of the second screw rod 33 is rotatably connected to the transmission rod 34, and the second screw rod 33 is threadedly connected to the top plate 31. The top end of the second screw rod 33 is provided with a handle for driving the second screw rod 33 to rotate. The second screw rod 33 is rotated, and the second screw rod 33 rotates and moves up and down, and the second screw rod 33 drives the transmission rod 34 to move up and down, and the transmission rod 34 drives the pressing plate 32 to move up and down through the first connecting rod 35, the second connecting rod 36 and the third connecting rod 37, so that the workpiece is pressed on the support plate 21 to fix the workpiece.

[0052] The laser additive-welding method of the above-mentioned dissimilar material laser additive-welding device based on gradual transition comprises the following steps:

[0053] S1. Place the workpieces to be welded on the support plate 21 , adjust the distance between the workpieces to be welded, that is, reserve a gap, and the movable plate 24 presses the workpieces tightly between the movable plate 24 and the second fixed plate 23 under the action of the second spring 27 .

[0054] S2. Rotate the second screw rod 33, the second screw rod 33 drives the transmission rod 34 to move downward, the transmission rod 34 drives the pressure plate 32 to move downward through the first connecting rod 35, the second connecting rod 36 and the third connecting rod 37, and the pressure plate 32 is pressed against the upper surface of the workpiece to fix the workpiece.

[0055] S3, the robot arm drives the mounting plate 11 to move to the connection of the workpieces to be welded, and adjusts the position of the multi-source laser welding head 12 so that the multi-source laser welding head 12 is located directly above the connection of the workpieces to be welded.

[0056] S4, rotate the first screw rod 19, the first screw rod 19 drives the lifting plate 17 to move up and down, the lifting plate 17 drives the multi-source laser welding head 12 to move up and down synchronously, the lifting plate 17 drives the second powder feeding tube 14 and the third powder feeding tube 15 to rotate through the connecting rod 110, adjust the angle of the second powder feeding tube 14 and the third powder feeding tube 15, the second powder feeding tube 14 and the third powder feeding tube 15 drive the sleeve 120 to move through the second limiting rod 119, the sleeve 120 drives the connecting plate 118 to move synchronously through the transmission gear 121 and the rack, the transmission gear 121 rotates under the action of the transmission rack 122 during the movement, the transmission gear 121 drives the connecting plate 118 to slide in the sleeve 120 through the rack, thereby adjusting the angle of the first powder feeding tube 13 and the fourth powder feeding tube 16, so that the distance between adjacent powder spreading points is not more than 0.05 mm, the blue light laser spot 129 covers the first powder spreading point 130 and the fourth powder spreading point 133, and the semiconductor laser spot 128 covers the upper surface of the workpiece.

[0057] S5, start the semiconductor laser 126 and the blue laser 127, start the powder feeder, and the robot arm drives the multi-source laser welding head 12 and the powder feeding tube to move along the connection of the workpieces to be welded through the mounting plate 11 to weld the workpieces to be welded.

[0058] Example 1

[0059] This embodiment takes SLM printing of AlSi10Mg aluminum alloy components and SLM printing of TC4 titanium alloy components as examples. The aluminum alloy side is close to the first powder feeding tube 13, and the titanium alloy is close to the fourth powder feeding tube 16. The mass percentage compositions of the mixed powders in the first powder feeding tube 13, the second powder feeding tube 14, the third powder feeding tube 15, and the fourth powder feeding tube 16 are: 80% Al + 20% Ti, 60% Al + 40% Ti, 40% Al + 60% Ti, and 20% Al + 80% Ti. The thickness of the workpiece is 2mm, the reserved gap of the workpiece is 1.5mm, the semiconductor laser power used in the welding process is 2500W, the blue laser power is 500W, the welding speed is 800mm / s, the powder feeding speed is 500g / min, and the defocus is 0. After the welding is completed, the formation of intermetallic compounds in the weld area can be effectively reduced, and the strength and toughness of the welded joint can be improved.

[0060] Example 2

[0061] Taking SLM printing AlSi10Mg aluminum alloy components (fine grains) and LMD printing AlSi10Mg aluminum alloy components (coarse grains) as examples, the SLM printing aluminum alloy components are close to the first powder feeding tube 13, and the LMD printing alloy components are close to the fourth powder feeding tube 16. The mass percentage compositions of the mixed powders in the first powder feeding tube 13, the second powder feeding tube 14, the third powder feeding tube 15, and the fourth powder feeding tube 16 are: 94.5% Al + 5% Mg + 0.5% TiC, 94% Al + 5% Mg + 1% TiC, 93.5% Al + 5% Mg + 1.5% TiC, 93% Al + 5% Mg + 2% TiC. The workpiece reserved gap is 1mm, the workpiece thickness is 2mm, the semiconductor laser power is 2000W, the blue laser power is 500W, the welding speed is 700mm / s, the powder feeding speed is 400g / min, and the defocus is 0. After welding is completed, the microstructure heterogeneity of the weld joint can be effectively reduced, the stress concentration phenomenon of the weld can be significantly improved, and the strength and toughness of the weld joint can be improved.

[0062] Therefore, the use of the dissimilar material laser additive-welding device and method based on gradual transition described in the present invention can solve the problem of low efficiency in connecting existing dissimilar metal materials and improve the welding quality of dissimilar thin-walled metals.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A dissimilar material laser additive-welding device based on gradual transition, characterized in that: It includes a workbench, a fixing mechanism for fixing a workpiece is arranged above the workbench, an additive welding mechanism is arranged above the workbench, the additive welding mechanism is located between two fixing mechanisms, and the additive welding mechanism is arranged on a mechanical arm; the additive welding mechanism includes a mounting plate, a multi-source laser welding head is arranged on the mounting plate, and a plurality of powder feeding pipes are symmetrically arranged on both sides of the multi-source laser welding head, and the powder feeding pipe contains a mixed powder containing alloy elements of two different materials, and the proportion of the base material powder in the mixed powder decreases gradually from one end close to the base material to the other end; a height adjustment structure for adjusting the height of the multi-source laser welding head is arranged on the mounting plate, and the height adjustment structure is connected to the powder feeding pipe through an angle adjustment structure; The powder feeding tube comprises a first powder feeding tube, a second powder feeding tube, a third powder feeding tube and a fourth powder feeding tube which are arranged in sequence. The top ends of the first powder feeding tube, the second powder feeding tube, the third powder feeding tube and the fourth powder feeding tube are hinged to the mounting plate. The first powder feeding tube, the second powder feeding tube, the third powder feeding tube and the fourth powder feeding tube respectively form a first powder spreading point, a second powder spreading point, a third powder spreading point and a fourth powder spreading point on the horizontal plane where the upper surface of the workpiece is located. The first powder spreading point, the second powder spreading point, the third powder spreading point and the fourth powder spreading point are located in a semiconductor laser spot formed by a semiconductor laser on the upper surface of the workpiece, and the semiconductor laser spot covers the upper surface of the workpiece. The blue light laser forms a blue light laser spot on the upper surface of the workpiece, and the blue light laser spot covers the first powder spreading point and the fourth powder spreading point. The second powder spreading point and the third powder spreading point are located in the blue light laser spot. The distance between adjacent powder spreading points of the first powder spreading point, the second powder spreading point, the third powder spreading point and the fourth powder spreading point is not greater than 0.05 mm. The angle adjustment structure includes connecting rods, which are arranged on both sides of the lifting plate, one end of the two connecting rods is hinged to the two end heads of the lifting plate respectively, the other end of one connecting rod is hinged to the second powder delivery pipe, and the other end of the other connecting rod is hinged to the third powder delivery pipe; an arc-shaped first limiting groove having a guiding effect on the rotation of the second powder delivery pipe and the third powder delivery pipe is provided on the mounting plate; the second powder delivery pipe and the first powder delivery pipe, and the third powder delivery pipe and the fourth powder delivery pipe are all connected through a connecting structure, and an arc-shaped second limiting groove having a guiding effect on the rotation of the first powder delivery pipe and the fourth powder delivery pipe is provided on the mounting plate; The connecting structure includes a sleeve and a connecting plate, a first limiting rod is rotatably provided at one end of the connecting plate, the first limiting rod is located in the second limiting groove, the first limiting rod is connected to the first powder feeding pipe or the fourth powder feeding pipe, a second limiting rod is rotatably provided at one end of the sleeve, the second limiting rod is located in the first limiting groove, the second limiting rod is connected to the second powder feeding pipe or the third powder feeding pipe, one end of the connecting plate is inserted in the sleeve and slidably connected to the sleeve, a transmission gear is rotatably provided below the sleeve, an opening is provided on the side wall of the sleeve for inserting the transmission gear into the sleeve, a rack is provided at the bottom of the transmission gear and the connecting plate is meshed, a transmission rack is provided below the transmission gear, a first fixed plate is provided below the transmission rack, the first fixed plate is fixedly provided on the mounting plate, a vertical support rod is provided on the transmission rack, a through hole is provided on the first fixed plate for the support rod to pass through, the support rod is slidably connected to the first fixed plate, a first spring is provided between the transmission rack and the first fixed plate, and the transmission rack is always meshed with the transmission gear under the action of the first spring.

2. The dissimilar material laser additive-welding device based on gradual transition according to claim 1, characterized in that: The multi-source laser welding head comprises a semiconductor laser and a blue light laser. The wavelength of the semiconductor laser is greater than that of the blue light laser. The wavelength of the semiconductor laser is 915 nm, and the wavelength of the blue light laser is 450 nm.

3. The dissimilar material laser additive-welding device based on gradual transition according to claim 2, characterized in that: Mounting seats are rotatably provided at both ends of the mounting plate, an air supply pipe is provided on the mounting seat, the air supply pipe is connected to an external inert gas bottle, a turntable is provided on the mounting seat, and a locking wire for locking the turntable and the mounting plate is provided on the turntable.

4. The dissimilar material laser additive-welding device based on gradual transition according to claim 3 is characterized in that: The height adjustment structure includes a lifting plate, a multi-source laser welding head is fixed on the lifting plate, a first screw rod is rotatably arranged on the mounting plate, a threaded hole is arranged on the lifting plate for the first screw rod to pass through and is adapted to the first screw rod, a motor or a knob is arranged on the top of the first screw rod to drive the first screw rod to rotate, a slide rail is arranged on the mounting plate to guide the lifting and lowering of the lifting plate, a slide groove adapted to the slide rail is arranged on the lifting plate, and the slide rail is located in the slide groove and is slidably connected to the slide groove.

5. The dissimilar material laser additive-welding device based on gradual transition according to claim 4, characterized in that: The workbench includes a support plate, the workpiece is placed on the support plate, the support plate is provided with an avoidance groove, and the connecting ends of the two workpieces are located directly above the avoidance groove; positioning structures for positioning the two workpieces are respectively provided on both sides of the avoidance groove, and the positioning structure includes a second fixed plate and a movable plate which are relatively arranged, the second fixed plate is fixedly arranged on the support plate, and a horizontal guide rod is arranged at one end of the movable plate away from the second fixed plate, a guide hole for the guide rod to pass through is arranged on the side of the support plate, the guide rod is slidably connected to the support plate, a second spring is arranged between the movable plate and the side, and a guide groove which has a guiding function for the horizontal sliding of the movable plate is arranged on the support plate.

6. The dissimilar material laser additive-welding device based on gradual transition according to claim 5, characterized in that: The fixing mechanism includes a top plate, the top plate is located above the supporting plate and is fixedly connected to the supporting plate, a pressure plate is arranged below the top plate, a vertical sliding rod is arranged on the pressure plate, a sliding hole is arranged on the top plate for the sliding rod to pass through, the top plate and the sliding rod are slidably connected, and the pressure plate is located between the second fixed plate and the movable plate; a transmission rod is arranged between the top plate and the pressure plate, the two ends of the transmission rod are respectively hinged with a first connecting rod, the other end of the first connecting rod is hinged with a second connecting rod and a third connecting rod, the other end of the second connecting rod is hinged with the top plate, the other end of the third connecting rod is hinged with the pressure plate, a second screw rod is arranged on the top plate to drive the transmission rod to move up and down, the bottom end of the second screw rod is rotatably connected to the transmission rod, the second screw rod is threadedly connected to the top plate, and the top end of the second screw rod is provided with a handle to drive the second screw rod to rotate.

7. A laser additive-welding method based on a dissimilar material laser additive-welding device based on gradual transition according to claim 6, characterized in that: The following steps are involved: S1. Place the workpieces to be welded on the support plate, adjust the distance between the workpieces to be welded, and the movable plate presses the workpieces tightly between the movable plate and the second fixed plate under the action of the second spring; S2, rotating the second screw rod, the second screw rod drives the transmission rod to move downward, the transmission rod drives the pressing plate to move downward through the first connecting rod, the second connecting rod and the third connecting rod, the pressing plate is pressed against the upper surface of the workpiece to fix the workpiece; S3, the robot arm drives the mounting plate to move to the connection of the workpieces to be welded, and adjusts the position of the multi-source laser welding head so that the multi-source laser welding head is located directly above the connection of the workpieces to be welded; S4, rotate the first screw rod, the first screw rod drives the lifting plate to move up and down, the lifting plate drives the multi-source laser welding head to move up and down synchronously, the lifting plate drives the second powder feeding tube and the third powder feeding tube to rotate through the connecting rod, adjust the angle of the second powder feeding tube and the third powder feeding tube, the second powder feeding tube and the third powder feeding tube drive the sleeve to move through the second limiting rod, the sleeve drives the connecting plate to move synchronously through the transmission gear and the rack, the transmission gear rotates under the action of the transmission rack during the movement, the transmission gear drives the connecting plate to slide in the sleeve through the rack, thereby adjusting the angle of the first powder feeding tube and the fourth powder feeding tube, so that the distance between adjacent powder spreading points is not more than 0.05mm, the blue light laser spot covers the first powder spreading point and the fourth powder spreading point, and the semiconductor laser spot covers the upper surface of the workpiece; S5. Start the semiconductor laser and the blue light laser, start the powder feeder, and the robot arm drives the multi-source laser welding head and the powder feeder to move along the connection of the workpieces to be welded through the mounting plate to weld the workpieces to be welded.

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