Ultra-narrow gap laser circular swing wire welding method for annular workpieces

Abstract

The present invention discloses an ultra-narrow gap laser circular swing wire filling welding method for an annular workpiece, and belongs to the field of laser processing technology. A groove with a blunt edge is processed at the welding position of the annular workpiece to be welded, and the annular workpiece to be welded is coaxially fixed; a laser head, a wire feeding nozzle and a gas feeding mechanism are symmetrically arranged directly above the groove; a laser beam circular swing method is used for laser self-melting welding of the blunt edge at the root of the groove; a laser beam circular swing method is used for multi-layer single-pass filling welding at the groove; and a laser beam circular swing method is used for single-pass cap welding. The use of laser circular swing can effectively solve the problems of side wall unfusion and interlayer unfusion defects, the weld grain size is significantly reduced, the performance of the weld is effectively improved, the weld surface is well formed, the weld is neat and flat, and the stability is good.

Description

Technical Field

[0001] The invention relates to a welding method for an annular workpiece, in particular to an ultra-narrow gap laser circular swing wire-filling welding method for an annular workpiece, belonging to the technical field of laser processing. Technical Background

[0002] In the research, development and manufacturing process of many mechanical equipment such as mining machinery, aerospace, nuclear power, shipbuilding, and automobile manufacturing, there is a need to perform circular welding on large medium-thick wall components such as shaft seats.

[0003] At present, the main methods for welding medium and thick plates are manual welding, submerged arc welding and gas shielded welding, but the above welding methods often produce coarse grains in the weld area and heat-affected zone. Compared with traditional arc welding, narrow gap laser wire welding technology has the advantages of small heat-affected zone, small welding deformation, high welding efficiency, etc. It can even further refine the grains, thereby achieving the effect of improving the mechanical properties of the joint, especially in the welding of thick plates. However, when welding shaft seat workpieces, due to the narrow groove of narrow gap laser wire welding and the more stringent welding requirements, after multiple welding passes, a large number of pores and a series of defects such as lack of fusion between layers and side walls will appear, which seriously affects the final welding effect and restricts the improvement of the industry's manufacturing level. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an ultra-narrow gap laser circular swing wire welding method which can effectively improve the welding quality to meet the welding requirements of annular workpieces.

[0005] In order to solve the above technical problems, the present invention provides an ultra-narrow gap laser circular swing wire welding method for annular workpieces, comprising the following steps:

[0006] S1, processing a groove with a blunt edge at a welding position of the annular workpiece to be welded, and coaxially fixing the annular workpiece to be welded;

[0007] S2, arrange the wire feeding nozzle, laser head and air supply mechanism in sequence just above the groove;

[0008] S3, laser self-melting welding is performed on the blunt edge of the groove root by circular swing of the laser beam;

[0009] S4, multi-layer single-pass filling welding is performed on the groove by circular oscillation of the laser beam;

[0010] S5, single-pass cap welding is performed using a circular oscillation of the laser beam.

[0011] Preferably, the circular swing is a clockwise circular swing.

[0012] Preferably, the angle between the laser head and the surface of the annular workpiece to be welded is 90°, the angle between the wire feeding nozzle and the laser head is 30°~70°, the angle between the gas supply mechanism and the laser head is 30°~70°, the dry extension of the welding wire is 5mm~15mm, the tip of the welding wire is tangent to the laser spot on the annular workpiece to be welded, the shielding gas flow rate is 15~18L / min, and the height of the gas supply mechanism from the surface of the annular workpiece to be welded is 11~13mm.

[0013] Preferably, in S3, the laser beam defocusing amount is +3 to +5 mm, the laser power is 3.6 KW, the oscillation frequency is 55 to 60 Hz, the laser spot diameter is 1.0 to 1.2 mm, and the welding speed is 0.6 to 0.8 m / min.

[0014] Preferably, in S4, when the filling pass is 1 to 4, the laser beam defocus is +14.5 to +15 mm, the laser power is 3.6 to 3.8 KW, the oscillation frequency is 55 to 60 Hz, the laser spot diameter is 1 to 1.5 mm, the welding speed is 0.48 to 0.54 m / min, and the wire feeding speed is 4.4 to 4.8 m / min;

[0015] When the filling pass is ≥5, the laser power is 3.8-3.9KW, the welding speed is 0.54-0.6m / min, and the wire feeding speed is 4.8-5.0m / min.

[0016] Preferably, in S5, the laser beam defocusing amount is +25 mm, the laser power is 3.8 KW, the oscillation frequency is 60 Hz, the laser spot diameter is 1.5-2.0 mm, the welding speed is 0.6 m / min, and the wire feeding speed is 4.6-4.8 m / min.

[0017] Preferably, the groove is a U-shaped groove, the blunt edge thickness of the groove is 5 mm, the root width of the groove is 3 mm, and the groove angle is 3° for one side and 6° for both sides.

[0018] Preferably, the gas in the gas supply mechanism is pure Ar with a purity of 99.999%.

[0019] The beneficial effects of the present invention are as follows: (1) in view of the defects such as spatter, pores, side wall and interlayer unfusion that occur in the narrow gap laser wire welding of annular workpieces, a galvanometer circular swing method is used for welding, and the beam swing is used to expand the laser action area, effectively increase the flow of the molten pool, inhibit the formation of spatter and pores, and reduce the line energy of the swing laser welding to increase the molten width, which is beneficial to the fusion of the side wall and the interlayer, and improve the weld quality, thereby optimizing and overcoming the problems caused by the relatively stringent welding requirements for the narrow gap laser wire welding of shaft seats, so that the stability of the molten pool, molten droplet transition and fuse capacity of the laser welding is greatly improved, the weld formation is better, the joint quality is high, and it is more suitable for the narrow gap laser wire welding of annular workpieces; (2) the swing laser welding process is adopted, so that the molten pool is fully stirred during the welding process, which promotes the overflow of pores and the fusion of the side walls. By reducing the linear heat input, the martensite in the heat affected zone is refined, the content of acicular ferrite and granular bainite is increased, and the structure of the heat affected zone of the intermediate layer undergoes a secondary thermal cycle, and the coarse grains are refined. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a schematic diagram of the galvanometer principle;

[0022] Figure 2 It is a schematic diagram of the arrangement of the laser head, wire feeding nozzle and gas feeding mechanism;

[0023] Figure 3 It is a schematic diagram of the circular oscillation motion trajectory of the laser beam;

[0024] Figure 4 The macroscopic morphology of the weld of the ultra-narrow gap laser welding head of the annular workpiece;

[0025] Figure 5 The microstructure comparison of the welded joints under two welding methods: laser non-oscillation and laser circular oscillation.

[0026] Figure 6 Comparison of weld cross-sectional morphology of welded joints under two welding methods: laser non-oscillation and laser circular oscillation;

[0027] Figure 7 This is a schematic diagram of the welding equipment structure;

[0028] Figure 8 This is a schematic diagram of the structure of the laser welding equipment.

[0029] Fig. 9 Schematic diagram of the implementation of welding equipment Figure 1 ,

[0030] Fig.10 Schematic diagram of the implementation of welding equipment Figure 2 ,

[0031] Fig.11 Schematic diagram of the implementation of laser welding equipment Figure 1 ,

[0032] Fig.12 Schematic diagram of the implementation of laser welding equipment Figure 2 ,

[0033] Fig.13 This is a schematic diagram of the structure of lifting device 1, lifting device 2, and lifting device.

[0034] Fig.14 is a structural diagram of a lifting device 1,

[0035] Fig.15 It is a structural diagram of the lifting device 2.

[0036] Fig.16 It is a structural schematic diagram of the lifting device.

[0037] In the figure: 1-working table, 2-lifting device 1, 3-lifting device 2, 4-lifting device, 5-three-jaw chuck 1, 6-three-jaw chuck 2, 7-pushing device, 8-axle seat clamping piece 1, 9-axle seat clamping piece 2, 10-laser head, 11-air supply mechanism, 12-wire supply mechanism, 13-slag cleaning brush, 14-laser beam, 15-fixed reinforcement plate 1, 16-fixed reinforcement plate 2, 17-area to be welded, 18-narrow gap groove;

[0038] 21-lifting platform 1, 22-linear drive mechanism 1, 23-base 1; 31-lifting platform 2, 32-linear drive mechanism 2, 33-base 2; 41-lifting platform, 42-linear drive mechanism 3, 43-lifting base;

[0039] 101-linear guide, 102-rack, 103 is the travel gear, 104 is the travel motor; 111-air nozzle, 121-wire nozzle, 122-filling wire, α-45°, β-30°. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0046] like Figure 1As shown in the figure, laser oscillating welding uses a scanning galvanometer to realize the oscillation of the focused beam, and uses the oscillation of the beam to expand the laser action area. Compared with traditional fixed beam laser welding, it has the advantages of high welding accuracy, good weld quality and formability, low requirements for the gap of plate splicing, and high welding flexibility. Studies have shown that laser oscillating welding can effectively increase the flow of the molten pool, inhibit the formation of spatter and pores, and reduce the line energy of oscillating laser welding to increase the molten width, which is beneficial to the fusion of the side wall and the interlayer, and improve the weld quality, thereby optimizing and overcoming the problems caused by the strict welding requirements for the narrow gap laser wire welding of the shaft seat.

[0047] like Figure 2 , 7 -16, the welding equipment used in the ultra-narrow gap laser circular swing wire welding method of the annular workpiece includes a workbench 1, a three-jaw chuck 1 5 and a three-jaw chuck 2 6 for clamping the workpiece, the three-jaw chuck 1 5 is fixedly connected to the workbench 1, the three-jaw chuck 2 6 is slidably connected to the workbench 1, and performs linear reciprocating motion along the length direction of the workbench under the drive of the push-up device 7, and the three-jaw chuck 1 5 and the three-jaw chuck 2 6 are arranged opposite to each other. The three-jaw chuck 1 5 clamps the shaft seat clamp 1 8, and the three-jaw chuck 2 6 clamps the shaft seat clamp 2 9. The workbench 1 is also connected to a laser welding device, which includes a laser head bracket, a laser head 10, an air supply mechanism 11, a wire supply mechanism 12, and a slag cleaning brush 13.

[0048] The laser head 10 is fixedly connected to the laser head bracket, and a laser beam 14 is emitted to the position to be welded through the laser head 10. The wire feeding mechanism 12 is arranged on one side of the laser head 10, and the welding wire is delivered to the position to be welded through the wire feeding mechanism 12. In this embodiment, the laser head 10 used is IPG D30, and the wire feeding nozzle 121 is a high-precision copper wire feeding nozzle, which are conventional technical means in the prior art, and therefore, they are not described in detail here.

[0049] The gas supply mechanism 11 includes a protective gas pipe connected to the protective gas, through which the protective gas is blown to the welding position, and the slag cleaning brush 13 is connected to the laser head 10, and the slag cleaning brush 13 and the wire feeding mechanism 12 are located on both sides of the laser head 10. The gas supply mechanism 11 adopts a single-row five-mouth copper gas supply nozzle.

[0050] The wire feeding mechanism 12 is connected to the laser head bracket through a fixed reinforcing plate 15; the fixed reinforcing plate 15 is fixedly connected to the laser head bracket, and a pair of vertically arranged long strip through holes are provided on the fixed reinforcing plate 15. A pair of bolts 1 are connected to the wire feeding mechanism 12, and the pair of bolts 1 are respectively located in the two long strip through holes, and the fixed connection between the wire feeding mechanism 12 and the fixed reinforcing plate 15 is realized through the pair of bolts 1. Thus, the height of the wire feeding mechanism 12 is adjustable, and the angle between the wire feeding mechanism and the laser head is adjustable, so as to better complete the wire feeding work.

[0051] The protective air pipe and the slag brush 13 are connected to the bottom of the laser head 10 through the fixed reinforcing plate 2 16; the bottom of the laser head 10 is provided with a round hole and an arc hole, and the fixed reinforcing plate 2 16 is connected with a pair of bolts 2, and the pair of bolts 2 are respectively located in the round hole and the arc hole, and the laser head and the fixed reinforcing plate 2 16 are fixedly connected by the pair of bolts 2, and there are multiple protective air pipes, and the multiple protective air pipes are fixedly connected to the fixed reinforcing plate 2 16, and the multiple protective air pipes are parallel to each other, so that the angle between the protective air pipe and the laser head is adjustable; the slag brush 13 is fixedly connected to the fixed reinforcing plate 2 16 through bolts 3, and since the slag brush 13 and the fixed reinforcing plate 2 16 have only one fixed connection point, the angle between the slag brush 13 and the fixed reinforcing plate 2 is also adjustable. Finally, the protective air pipe and the slag brush can be placed in different predetermined positions with the help of the fixed reinforcing plate 2, so as to better complete the blowing and cleaning work.

[0052] The protective gas is one gas or a mixture of multiple gases including Ar, CO2 and He.

[0053] The slag cleaning brush comprises a brush head made of hard alloy and a motor. The motor is connected to the laser head 10, and the brush head is driven by the motor to rotate to clean the slag.

[0054] The angle between the wire feeding mechanism 11 and the welding direction is acute, and welding is performed in a front wire feeding manner.

[0055] The included angle between the wire feeding mechanism 11 and the laser beam emitted by the laser head 9 is between 20 and 80 degrees; the included angle between the laser beam and the protective air pipe 10 is between 20 and 80 degrees.

[0056] The angle between the wire feeding mechanism and the welding direction is acute, and the front wire feeding method is used for narrow gap laser wire welding. In the process of narrow gap laser wire welding, the laser direction, the wire filling direction and the direction of the shielding gas introduction form different combinations. Front wire feeding and rear wire feeding are the two basic wire feeding methods for laser wire welding. Front wire feeding is to feed the front of the welding wire molten pool into the molten pool at an acute angle to the welding direction; rear wire feeding is to feed the welding wire from the rear of the molten pool into the molten pool at an obtuse angle to the welding direction; side wire feeding is to feed the welding wire into the molten pool from both sides of the molten pool or both sides of the welding direction. The wire feeding method affects the heating principle of the welding wire and plays a decisive role in the melting and filling process of the welding wire. In post-wire welding, the energy cannot achieve rapid and sufficient melting of the welding wire, so the reaction between the welding wire and the matrix is ​​insufficient, resulting in an unstable welding process and unsatisfactory weld formation. In front-wire welding, when the welding wire is far away from the laser beam, it mainly relies on the energy of metal vapor and photoplasma and the energy of the molten pool to melt. When it is close to the laser beam, the welding wire is directly irradiated by part of the laser and is further heated and melted. The melting is sufficient, the melting process of the welding wire is continuous and stable, and the welding wire first melts into the front molten pool and flows to the rear with the molten liquid. The welding wire can be evenly melted into the weld.

[0057] The laser beam emitted by the laser head and the welding wire of the wire feeding mechanism are Angle, the angle value is between 20 and 80°. Due to the small size of the groove, the welding wire needs to be inserted into the bottom of the groove for welding. For deep grooves, since the diameter of the wire feed nozzle is larger than the width of the upper surface of the groove, the welding wire can only be inserted into the deep groove. The welding wire needs to be extended by about 40mm, which has extremely high requirements for the correction of the welding wire. If the welding wire swings during the welding process, the laser beam will not be able to irradiate the welding wire, resulting in unfused defects, which will directly affect the welding effect. Before welding, the wire feeding mechanism is arbitrarily adjusted in the direction of the wire feeding weld through the regulator, and The angle can be adjusted within a certain range, and the optimal angle can be selected for wire feeding to ensure welding quality.

[0058] Follow these steps:

[0059] Step 1: Assemble the workpiece to be welded, spot weld the back of the workpiece, and support the workpiece to be welded;

[0060] Step 2: Move the laser head to the starting point of the workpiece to be welded for alignment, so that the center of the light spot falls on the gap of the unwelded workpiece, and record this spatial point to mark the welding end point;

[0061] Step 3: Use the wire feeding mechanism to send the front end of the welding wire to the center of the light spot so that the light spot falls on the front end of the welding wire; when welding, turn on the laser head, protective gas pipe, wire feeding mechanism, and slag cleaning brush at the same time.

[0062] In the narrow gap laser wire-filling welding process of shaft seat-type workpieces, the present invention uses a slag-cleaning brush to act on the weld bead. Since the shaft seat-type workpiece is heavy and welding positioning is difficult, the present case also proposes the following further improved design, so that the position to be welded can be accurately positioned by a lifting device and a lifting device. In conjunction with the narrow gap laser wire-filling welding equipment, the welding of shaft seat-type workpieces is completed, wherein the slag-cleaning brush directly acts on the weld bead and the side wall, causing the welding slag attached to the weld bead and the side wall to peel off, so as to ensure the quality of interlayer welding. This design not only accurately positions the shaft seat-type welding position, but also can avoid interlayer and side wall defects during welding.

[0063] A lifting device 1 2, a lifting device 2 3 and a lifting device 4 are also provided between the three-jaw chuck 1 5 and the three-jaw chuck 2 6. A linear guide rail 10 provided along the length direction of the workbench 1 is fixedly connected thereto. The lifting device 1 2, the lifting device 2 3 and the lifting device 4 are all slidably connected to the linear guide rail 101.

[0064] The lifting device 2 includes a lifting platform 21, a linear drive mechanism 22 and a base 23. The base 23 is slidably connected to the linear guide rail 101. The lifting platform 21 is connected to the top of the base 23 via the linear drive mechanism 22. A pair of supporting rods parallel to the length direction of the workbench are provided on the lifting platform 21. Thus, the end of the workpiece with better consistency is lifted by the lifting device 2.

[0065] The lifting device 23 includes a lifting platform 231, a linear drive mechanism 232 and a base 233. The base 233 is slidably connected to the linear guide rail 101. The lifting platform 231 is connected to the top of the base 233 via the linear drive mechanism 232. The lifting platform 231 is provided with a plurality of supporting wheels parallel to the length direction of the workbench. Thus, the end of the workpiece with poor consistency is lifted by the lifting device 23.

[0066] The lifting device 4 includes a lifting platform 41, a linear drive mechanism 3 42 and a lifting base 43. The lifting base 43 is slidably connected to the linear guide rail 101. The lifting platform 41 is connected to the lifting base 43 via the linear drive mechanism 3 42. A pair of straight rollers parallel to the length direction of the workbench and a pair of V-shaped rollers perpendicular to the length direction of the workbench are provided on the lifting platform 41. Thus, the workpiece can be supported better and more stably when the workpiece is welded.

[0067] When in use, lifting device 1 2 and lifting device 2 3 are mainly responsible for the posture control of the shaft seat workpiece. Since the shapes of the two ends of the shaft seat workpiece may be different, the top morphologies of lifting device 1 2 and lifting device 2 3 are different. Lifting device 1 2 mainly lifts the end of the workpiece with better consistency, and lifting device 2 3 lifts the end of the workpiece with poor consistency. The two sets of lifting devices lift the workpiece to the same horizontal plane to ensure that the center line of the shaft of the shaft seat workpiece coincides with the center line of the three-jaw chuck 1 5 and the three-jaw chuck 2 6. The push-up device 7 is fixed on the bed and extended by the motor. Or retract the ejector rod, move the shaft seat support part 1 8 and the shaft seat support part 2 9 to push into the shaft seat part to fix it, the ejector device 7 is fixed on the bed, and the motor extends or retracts the ejector rod, and then the three-jaw chuck 2 6 is used to push and clamp the shaft seat workpiece, and the lifting device 4 is raised to the surface of the workpiece to support the workpiece during the welding process, and then the lifting device 1 2 and the lifting device 2 3 are lowered to the bottom. During welding, the lifting device 4 supports the main body of the shaft seat, and the automatic lifting device is not subjected to force and remains in a lowered state. When the welding is completed, the lifting device 1 2 and the lifting device 2 3 are raised to the surface of the shaft seat workpiece, the ejector device 7 unloads the force and withdraws, the lifting device 1 2 and the lifting device 2 3 are raised, and the shaft seat workpiece is supported, and it is lowered together with the lifting device 4, and the shaft seat workpiece is removed by hoisting equipment.

[0068] The shaft seat narrow gap laser wire filling welding equipment also includes a travel drive mechanism, which includes a rack 102 , three travel gears 103 and three travel motors 104 .

[0069] The rack 102 is arranged parallel to the linear guide rail 101 and fixedly connected to the workbench; three travel motors 104 are respectively fixedly connected to the base 1 23, the base 2 33 and the lifting base 43, and three travel gears 103 are respectively connected to the output shafts of the three travel motors 104, and the three travel gears 103 are all meshed with the rack. Thus, the lifting device 1 2, the lifting device 2 3 and the lifting device 4 can be independently controlled to move back and forth on the workbench.

[0070] The ultra-narrow gap laser circular swing wire welding method of the present invention is now described in detail by taking a ring-shaped workpiece as an example, and the specific steps are as follows:

[0071] Step 1, groove design: The annular workpiece to be welded consists of two shaft seats and a tube. The shaft seats and the ends of the tube are respectively machined with grooves with blunt edges. The blunt edge thickness is 2-5mm, the groove root width is 3mm, and the groove angle is 3°. After the annular workpiece to be welded is butt-jointed, a groove angle of 6° is formed, i.e., the welding area 17, such as Figure 2 shown.

[0072] Step 2: Assembly and fixation: When assembling the annular workpiece to be welded, use a level to position the shaft seats at both ends to ensure that the screw holes on the two shaft seats are on the same vertical line, and then use a handheld laser to weld in the narrow gap groove 18 with an interval of 70 to 90 mm, and weld 9 to 11 mm to fix it to prevent it from falling off during placement in the fixture. Then, place the annular workpiece to be welded in the annular workpiece fixture by a crane, and set the fixture holding force to 1.5T to ensure that the annular workpiece to be welded maintains a uniform coaxiality during the welding process.

[0073] Step 3: Figure 2 As shown, the laser head 10, the wire feeding nozzle 121 and the gas supply mechanism 11 are symmetrically arranged just above the groove of the annular workpiece to be welded. Among them, the wire feeding nozzle 121 and the gas supply mechanism 11 are fixed on both sides of the laser head 10 respectively, and the laser head 10, the wire feeding nozzle 121 and the gas supply nozzle 111 in the gas supply mechanism 11 are in the same straight line and parallel to the weld; the angle between the laser head 10 and the surface of the annular workpiece to be welded is adjusted to 90°, the angle α between the wire feeding nozzle 121 and the laser head 10 is 45°, the angle β between the gas supply nozzle 111 and the laser head 10 is 30°, the dry extension length of the filler wire 122 is 5mm to 15mm, the tip of the filler wire 122 is tangent to the laser spot on the annular workpiece to be welded, the protective gas flow rate of the gas supply mechanism 11 is 15L / min, and the height of the gas supply mechanism 11 from the surface of the annular workpiece to be welded is 12mm.

[0074] Step 4: Laser self-melting welding: The blunt edge of the groove root is welded by laser self-melting welding. Set the laser beam 14 defocus amount to +3mm and the laser power to 3.6KW. Figure 3 The laser beam 14 swings in a clockwise circular swing mode, the swing frequency is 60 Hz, the laser spot diameter is 1.0 mm, and the welding speed is 0.6 m / min; the wire feeding program is turned off, the laser head 10 and the gas supply mechanism 11 are started, and the welding robot is linked to the annular workpiece fixture to weld the root of the groove.

[0075] Step 5, filling welding: Multi-layer single-pass filling welding is performed at the groove in a swinging manner, and the filling welding parameters are set. The laser head 10, the gas supply mechanism 11 and the wire feeding mechanism 12 are started, the wire is fed synchronously, and the welding robot is linked to the annular workpiece fixture to perform filling welding on the groove. The specific setting is that when the filling pass is 1 to 4 times, the defocus amount of the laser beam 14 is +15mm, the laser power is 3.6KW, the swing mode of the laser beam 14 is clockwise circular swing, the swing frequency is 60Hz, the laser spot diameter is 1.5mm, the welding speed is 0.48m / min, and the wire feeding speed is 4.4m / min; when the filling pass is ≥5, the laser power is 3.8KW, the welding speed is 0.6m / min, the wire feeding speed is 4.8m / min, and the other parameters are kept the same, and the filling thickness is controlled at 3mm; after the filling is completed, clean it and use a high-pressure air gun to blow off the smoke and welding slag covering the weld.

[0076] Step 6, cap welding: Use swinging mode to perform single-pass capping, set cap welding parameters, start the laser head 10, gas supply mechanism 11 and wire feeding mechanism 12, feed wire synchronously, and the welding robot links the annular workpiece fixture until the welding is completed. The specific settings are: the defocus of the laser beam 14 is +25mm, the laser power is 3.8KW, the swing mode of the laser beam 14 is clockwise circular swing, the swing frequency is 60Hz, the laser spot diameter is 2.0mm, the welding speed is 0.6m / min, and the wire feeding speed is 4.6m / min.

[0077] In this embodiment, in the above steps 4 to 6, the protective gas is introduced through the gas supply mechanism 11, and the gas is pure Ar (99.999%). The annular workpiece to be welded is 35 steel-Q355B, with a thickness of 12mm to 24mm.

[0078] In this embodiment, the laser filling welding in step five is single-pass multi-layer filling. After each layer of filling is completed, the weld oxide scale is removed with an air gun and cleaned with alcohol to ensure that there are no obvious impurities on the weld surface before the next welding. The weld morphology is neat and the stability is good.

[0079] from Figure 4 It can be seen that the weld surface formed by the laser circular swing welding method in this embodiment is well formed and the weld is neat and flat.

[0080] like Figure 5 As shown in Figure (1), in the laser non-oscillation welding mode, the weld grain size is obviously larger and irregular, and there are pores in the side wall area and the interlayer area to varying degrees; in Figure (2), in the laser circular oscillation welding mode, whether it is the side wall area, the interlayer area, or the middle area, the weld grain size is obviously smaller and relatively uniform, and there is no pore on the weld surface.

[0081] like Figure 6As shown in the figure, from the comparison of the weld cross-section morphology, it can be seen that in Figure (2), the weld cross-section formed by the laser non-swinging welding method has multiple irregularly distributed pores of different sizes, and the weld is irregular; in Figure (1), the weld cross-section formed by the laser circular swinging welding method is neat and flat, without any pores.

[0082] By comparing the welding joints under the two welding methods of laser non-oscillation and laser circular oscillation, it can be seen that the laser circular oscillation used in this embodiment can effectively solve the problems of side wall unfusion and interlayer unfusion defects, the weld grain size is significantly reduced, the performance of the weld is effectively improved, the weld surface is better formed, the weld is neat and flat, and the stability is good.

[0083] In Example 2, in step 3, the angle between the wire feeding nozzle 121 and the laser head 10 is 70°, and the angle between the gas supply mechanism 11 and the laser head 10 is 70°; the protective gas flow rate of the gas supply mechanism 11 is 18 L / min, and the height of the gas supply mechanism 11 from the surface of the annular workpiece to be welded is 13 mm;

[0084] In step 4, the defocus of the laser beam 14 is +5 mm, the laser power is 3.6 KW, the oscillation frequency of the laser beam 14 is 55 Hz, the laser spot diameter is 1.2 mm, and the welding speed is 0.8 m / min;

[0085] In step 5, when the filling pass is 1 to 4 times, the defocus of the laser beam 14 is +14.5 mm, the laser power is 3.8 KW, the oscillation frequency of the laser beam 14 is 55 Hz, the laser spot diameter is 1 mm, the welding speed is 0.54 m / min, and the wire feeding speed is 4.8 m / min; when the filling pass is ≥5, the laser power is 3.9 KW, the welding speed is 0.54 m / min, and the wire feeding speed is 5.0 m / min;

[0086] In step six, the laser spot diameter is 1.5 mm and the wire feeding speed is 4.8 m / min;

[0087] Other steps and parameters are the same as in Example 1.

[0088] In Example 3, the angle between the wire feeding nozzle 121 and the laser head 10 in step 3 is set to 30°, and other parameters are the same as in Example 1.

[0089] The present invention adopts a circular swing laser welding process to fully stir the molten pool during the welding process, promote the overflow of pores and the fusion of the side walls, and refine the martensite in the heat-affected zone by reducing the linear heat input, and increase the content of acicular ferrite and granular bainite. After the secondary heat cycle, the coarse grains in the heat-affected zone of the middle layer are refined, and the hardness is significantly reduced, which optimizes and overcomes the problems caused by the strict welding requirements for the narrow gap laser wire welding of the shaft seat, thereby improving the quality of the ultra-narrow gap laser wire welding of the annular workpiece.

[0090] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A method for ultra-narrow gap laser circular swing wire welding of annular workpieces, characterized in that The following steps are involved: S1, processing a groove with a blunt edge at a welding position of the annular workpiece to be welded, and coaxially fixing the annular workpiece to be welded; S2, arrange the wire feeding nozzle, laser head and air supply mechanism in sequence just above the groove; S3, laser self-melting welding is performed on the blunt edge of the groove root by circular swing of the laser beam; The laser beam defocus is +3 to +5 mm, the laser power is 3.6 KW, the oscillation frequency is 55 to 60 Hz, the laser spot diameter is 1.0 to 1.2 mm, and the welding speed is 0.6 to 0.8 m / min; S4, multi-layer single-pass filling welding is performed on the groove by circular oscillation of the laser beam; When the filling pass is 1 to 4, the laser beam defocus is +14.5 to +15 mm, the laser power is 3.6 to 3.8 KW, the swing frequency is 55 to 60 Hz, the laser spot diameter is 1 to 1.5 mm, the welding speed is 0.48 to 0.54 m / min, and the wire feeding speed is 4.4 to 4.8 m / min; When the filling pass is ≥5, the laser power is 3.8-3.9KW, the welding speed is 0.54-0.6m / min, and the wire feeding speed is 4.8-5.0m / min; S5, single-pass cap welding is performed by circular oscillation of the laser beam; the laser beam defocus is +25mm, the laser power is 3.8KW, the oscillation frequency is 60Hz, the laser spot diameter is 1.5-2.0mm, the welding speed is 0.6m / min, and the wire feeding speed is 4.6-4.8m / min.

2. The ultra-narrow gap laser circular oscillating wire welding method for annular workpieces according to claim 1 is characterized in that: The circular swing is a clockwise circular swing.

3. The ultra-narrow gap laser circular oscillating wire welding method for annular workpieces according to claim 1 or 2, characterized in that: The angle between the laser head and the surface of the annular workpiece to be welded is 90°, the angle between the wire feeding nozzle and the laser head is 30°-70°, the angle between the gas supply mechanism and the laser head is 30°-70°, the dry extension of the welding wire is 5mm-15mm, the tip of the welding wire is tangent to the laser spot on the annular workpiece to be welded, the flow rate of the shielding gas is 15-18L / min, and the height between the gas supply mechanism and the surface of the annular workpiece to be welded is 11-13mm.

4. The ultra-narrow gap laser circular oscillating wire welding method for annular workpieces according to claim 1 or 2, characterized in that: The groove is a U-shaped groove, the blunt edge thickness of the groove is 5 mm, the root width of the groove is 3 mm, and the groove angle is 3° on one side and 6° on both sides.

5. The ultra-narrow gap laser circular oscillating wire welding method for annular workpieces according to claim 1 or 2, characterized in that: The gas in the gas supply mechanism is pure Ar with a purity of 99.999%.

Images