Laser welding method and compressor

Abstract

The invention provides a laser welding method and a compressor, and the welding method comprises the following steps that a laser beam track and the moving speed of a first welding part and a second welding part are set, and the laser beam track comprises a swing track and a swing frequency; a first welding piece and a second welding piece are arranged, and at least two intersection points exist between the swing track and a to-be-welded gap between the first welding piece and the second welding piece; and the first welding piece and the second welding piece are moved at the moving speed, and a laser beam is started to weld the first welding piece and the second welding piece according to the laser beam track. According to the laser welding method, a larger gap can be welded through at least two-time intersection of the laser beam swing track and the to-be-welded gap, so that the arrangement precision between the to-be-welded parts is reduced, meanwhile, the effective sealing depth of a welding seam can be improved, and the welding sealing performance is improved.

Description

Technical Field

[0001] The present invention relates to the field of electrical connection, and in particular to a laser welding method and a compressor. Background Art

[0002] The upper shell cover (or lower shell cover) of the air-conditioning compressor is usually fixed to the shell using the Metal Active Gas Arc Welding (MAG) process. MAG welding uses a mixed gas as a protective agent and the electrode material as a filler material for welding. The disadvantages of this process are large welding deformation, which affects product precision; the compressor's conductivity during welding causes discharge and electro-erosion between the compressor's precision components, reducing product precision; large welding spatter, which requires rework after welding to scrape off the spatter; and the direct material cost investment required for the use of solder during welding.

[0003] To improve the above-mentioned problems of MAG welding and considering that the investment of welding wire will increase manufacturing costs, some compressor parts use laser welding without solder filling. However, laser welding has the following problems:

[0004] 1. Laser welding is not applicable to existing welding grooves. In the field of welding, different welding types require the design of corresponding welding grooves. The corresponding welding groove of existing MAG welding is V-shaped, which is a typical welding groove structure designed for filler welding method, which is conducive to the solder filling the V-shaped groove to form a high-quality weld during welding. However, laser welding is an autolytic welding type. There is no solder filling during welding, and a V-shaped groove is not required at the weld. Usually, the V-shaped groove is mainly set at the chamfer on the inner side of the shell. The chamfer also plays a guiding role. Canceling the groove will lose the above-mentioned guiding role, which will cause bumps during installation. How to apply laser autolytic welding to the V-shaped groove is a technical challenge.

[0005] 2. Product matching clearance affects the quality of laser welding. The shell cover and shell of the compressor are both round or curved. After the two are installed together, there is an installation gap. During laser welding, the laser beam will directly pass through the gap, causing leakage or insufficient penetration.

[0006] 3. Welding position deviation affects the quality of laser welding. Due to the influence of the curvature of the shell cover and the shell, the welding position will deviate during circumferential welding, resulting in false welding or leaking welding.

[0007] 4. Laser welding requires higher material cleanliness. During mass production, materials may be contaminated with oil or other imperfect cleanliness. Because the energy density of laser welding is higher than that of MAG welding, high-density heating is more likely to cause weld porosity. In severe cases, this can lead to blowouts, causing compressor leakage, impacting weld yield, and requiring rework and repair, which can also reduce production efficiency.

[0008] Therefore, how to improve the quality of laser welding is the problem to be solved by the present invention.

[0009] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0010] In response to the problems in the prior art, the purpose of the present invention is to provide a laser welding method and a compressor. The laser welding method can weld larger gaps by crossing the laser beam swing trajectory with the gap to be welded at least twice, thereby reducing the layout accuracy between the parts to be welded. At the same time, it can increase the effective sealing depth of the weld and improve the welding sealing performance.

[0011] A first aspect of the present invention provides a laser welding method, comprising the following steps:

[0012] S100: Setting a laser beam trajectory and movement speeds of the first welding part and the second welding part, wherein the laser beam trajectory includes an oscillation trajectory and an oscillation frequency;

[0013] S200: Arranging the first welding part and the second welding part, wherein the swing trajectory has at least two intersections with the gap to be welded between the first welding part and the second welding part;

[0014] S300: moving the first welding part and the second welding part at the moving speed, starting the laser beam to weld the first welding part and the second welding part along the laser beam trajectory.

[0015] According to the first aspect of the present invention, the swing trajectory is a combination of one or more of a polygon, a circle and an ellipse.

[0016] According to the first aspect of the present invention, the oscillation trajectory is symmetrical relative to the gap to be welded.

[0017] According to the first aspect of the present invention, the swing trajectory is a quadrilateral;

[0018] The spot diameter of the laser beam is D;

[0019] The first side length of the quadrilateral along the direction perpendicular to the extension direction of the welding gap is H;

[0020] The width of the welding gap between the first welding part and the second welding part is h, satisfying:

[0021] D + h / 2 ≤ H ≤ D + h.

[0022] According to the first aspect of the present invention, the second side length of the quadrilateral along the extension direction of the welding gap is L, satisfying: D < L; or

[0023] The second side length of the quadrilateral along the extension direction of the welding gap is L, satisfying: H < L.

[0024] According to the first aspect of the present invention, the swing frequency ≤ 100 Hz.

[0025] According to the first aspect of the present invention, the width of the welding gap between the first welding part and the second welding part is h, and the width h is less than or equal to 1.0 mm.

[0026] According to the first aspect of the present invention, the swing trajectory is realized by the swing of the internal galvanometer of the laser welding head.

[0027] The second aspect of the present invention provides a compressor, and the laser welding method is used for fixedly connecting at least two components of the compressor.

[0028] According to the second aspect of the present invention, the compressor includes an upper shell cover, a lower shell cover and a housing;

[0029] The upper shell cover and the housing, and the lower shell cover and the housing are fixedly connected by the laser welding method.

[0030] The laser welding method of the present invention reduces the direct material cost of the welding wire and improves the welding quality by at least two intersections of the laser beam swing trajectory and the welding gap. During the first intersection, pre-welding is carried out, and during the second intersection, the pre-welding defects are repaired. Further, the two laser beam trajectories along the extension direction of the welding gap in the swing trajectory can stir the molten pool to exclude the pores in the molten pool, enhance the ability to melt the base metal and converge and fill the stack height. Correspondingly, the laser welding method of the present invention can weld a larger gap, thereby reducing the layout accuracy between the workpieces to be welded, and at the same time, increasing the effective sealing depth of the weld and improving the welding sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, other features, objects and advantages of the present invention will become more apparent.

[0032] Figure 1is a flow chart of a laser welding method according to an embodiment of the present invention;

[0033] Figure 2 A top view of a laser welding method according to an embodiment of the present invention;

[0034] Figure 3 A cross-sectional view of a laser welding method according to an embodiment of the present invention; and

[0035] Figures 4 to 7 Schematic diagram of different stages of welding a compressor cover and a shell using a laser welding method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention. Identical reference numerals in the figures represent identical or similar structures, and thus their repeated description will be omitted.

[0037] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0039] The disclosure below provides many different embodiments or examples for implementing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0040] In order to solve the technical problems in the prior art, the present invention provides a laser welding method and a compressor, the welding method comprising the following steps: setting a laser beam trajectory and the moving speeds of a first welding part and a second welding part, the laser beam trajectory comprising an oscillation trajectory and an oscillation frequency; arranging the first welding part and the second welding part, the oscillation trajectory having at least two intersections with the gap to be welded between the first welding part and the second welding part; moving the first welding part and the second welding part at the moving speed, and starting the laser beam to weld the first welding part and the second welding part along the laser beam trajectory.

[0041] The laser welding method of the present invention crosses the laser beam swing trajectory with the gap to be welded at least twice, pre-welding is performed during the first intersection and pre-welding defects are repaired during the second intersection, thereby reducing the direct material cost of the welding wire and improving the welding quality; furthermore, the two laser beam trajectories in the swing trajectory along the extension direction of the gap to be welded can stir the molten pool to eliminate pores in the molten pool, enhance the ability to melt the parent material and converge the filling and stacking height. Accordingly, the laser welding method of the present invention can weld larger gaps, thereby reducing the layout accuracy between the parts to be welded, and at the same time, increase the effective sealing depth of the weld and improve the welding sealing performance.

[0042] The laser welding method and the compressor of the present invention are further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments are not intended to limit the scope of protection of the present invention.

[0043] Figure 1 Flowchart of a laser welding method according to an embodiment of the present invention. Specifically, the laser welding method includes the following steps:

[0044] S100: Setting the laser beam trajectory and the movement speed of the first and second welded parts. The oscillating trajectory is the path along which the laser beam oscillates. The present invention utilizes oscillating laser welding (dynamic laser welding), meaning the laser welding head of the laser welding equipment is an oscillating head. The oscillation of the laser beam is achieved by installing two high-speed galvanometer mirrors within the laser welding head. The high-speed oscillation of the galvanometer mirrors changes the direction and movement trajectory of the laser beam. The laser beam trajectory includes an oscillation trajectory and an oscillation frequency. The oscillation trajectory is the minimum period of the laser beam during oscillating laser welding. The oscillation trajectory can be polygonal, circular, or elliptical, or a combination of these, such as a figure-eight, an infinity, or a spiral. Special shapes can be achieved by programming the oscillation of the galvanometer mirrors within the laser welding head. Commonly used laser welding equipment is equipped with setup software. During welding, the laser oscillation welding function is selected and the laser beam oscillation trajectory parameters are set, such as the diameter of the oscillation trajectory for a circular oscillation and the length and width of the oscillation trajectory for a rectangular oscillation. This is not further detailed here.

[0045] S200: Arrange the first and second weld parts, with the swing trajectory intersecting at least two points with the gap to be welded between the first and second weld parts. Prior to this arrangement, the areas to be welded of the first and second weld parts may undergo pre-weld treatment such as grinding, pickling, or laser cleaning. The initial positions of the first and second weld parts are arranged here. During welding, the first and second weld parts will move, specifically, the gap to be welded between them will move as a whole. The actual welding trajectory is the coupling of the laser beam trajectory and the movement trajectory of the first and second weld parts.

[0046] Figure 2 and Figure 3 The following are top and cross-sectional views of a laser welding method according to an embodiment of the present invention, respectively. For example, the swing trajectory is a quadrilateral. The first side of the quadrilateral, perpendicular to the direction of the gap to be welded, is H, and the second side of the quadrilateral, along the direction of the gap to be welded, is L. Preferably, the quadrilateral is a rectangle, in which case L is the long side of the rectangle and H is the short side of the rectangle. The first and second weld parts are arranged below the laser welding head, and the gap to be welded is positioned within the quadrilateral's swinging area. The swing trajectory is symmetrical with respect to the gap to be welded, i.e., the gap to be welded is located at the center axis of the short side H of the quadrilateral. In actual use, the laser equipment can be equipped with forward vision guidance to ensure that the gap to be welded remains between the two long sides of the rectangular swing trajectory during welding. If the gap to be welded deviates onto or outside any of the long sides of the quadrilateral, the other long side will be ineffectively welded, which will reduce the ability to melt the base material during welding and reduce the quality of the weld.

[0047] In the above embodiment, during welding, the gap between the materials to be welded can be rotated clockwise, such as Figure 2 As shown by the dotted arrow, the laser welding head is stationary for welding, and the set laser beam swing trajectory is obtained under the high-speed movement of the high-speed steering galvanometer in the laser welding head. The laser beam takes point A1 as the starting point and swings along the quadrilateral trajectory. The gap to be welded between the first welding part and the second welding part moves clockwise relative to the laser beam light-emitting trajectory, passes point A2 and returns to point A1. This is a quadrilateral light-emitting cycle. The swing frequency in step S200 is the number of times the swing trajectory is completed within 1 second. If the swing frequency is 100 Hz, the laser beam can complete 100 quadrilateral swing trajectories within 1 second.

[0048] After step S200 is completed, step S300 is executed: the first weld part and the second weld part are moved at the movement speed, and the laser beam is activated to weld the first weld part and the second weld part along the laser beam trajectory. The laser equipment used in the present invention can be a single-mode laser or a multi-mode laser. The laser power can be 500W or greater, and an optical fiber with a core diameter of 50μm or greater can be used. The oscillation linear speed can be 2000 mm / s or greater. The shielding gas during welding can be nitrogen or argon, with a gas flow rate of at least 2.0 liters / minute.

[0049] During the welding process of step S300, when the laser beam passes through point A1, it is the first welding. When it passes from point A1 on one side of the gap to be welded to point A2, and then from point A2 on the other side of the gap to be welded to point A1, the parent materials on both sides of the gap to be welded melt, converge to fill and stack the welds, thereby increasing the effective sealing depth of the welds and improving the welding sealing performance. Finally, when passing through point A2, the weld is shaped to obtain a high-quality weld. When there are defects in the gap to be welded, such as poor material cleanliness, oil stains, etc., resulting in welding defects such as blast holes, weld collapse, and pores, when the laser beam passes through A1-A2, the parent materials of the two long sides L of the quadrilateral melt, converge to fill and repair the weld defects, and stack the existing welds at the same time. Finally, when passing through point A2, two weldings are performed to finally repair the weld defects and complete the self-healing welding mechanism.

[0050] In the welding method of the present invention, the first intersection point of the oscillating trajectory and the gap to be welded is A1, and the second intersection point is A2. The movement speed of the first and second weld parts can be designed so that the movement speed of the gap to be welded is at least less than 1 / 2 of the speed of the long side of the laser beam along the oscillating trajectory, so that the second intersection point A2 at least partially overlaps with the first intersection point A1. At this time, the two long sides of the rectangle melt the shell and shell cover base materials respectively, and the melted materials intersect to fill the material gap. At the same time, due to the movement of the gap to be welded, when the oscillating trajectory passes through the gap to be welded twice, it welds the same gap to be welded. The first weld can be considered as a pre-weld, which plays the role of cleaning the weld point, and the second weld can be considered as repairing the defects at the pre-weld point. By welding twice at the same position in the gap to be welded, the welding quality can be improved, such as increasing the effective sealing depth and sealing performance of the weld. In addition, for special materials, such as materials prone to pores and cracks, the oscillation of the laser beam in the welding method of the present invention acts as a "stirring effect", which can improve the grain size of the weld area and eliminate welding defects such as pores and cracks. For example, when welding with a circular oscillating trajectory, the repetitive welding area is large, and the laser beam repeatedly heats the molten pool, stirring the molten pool to help release pores and refine the weld grain size. The grain size of the weld seam produced by the present invention can range from 0.05mm to 0.2mm. Existing laser welding methods (not using oscillating welding) generally produce welds with a grain size greater than 0.2mm.

[0051] To further improve the welding effect, in the welding method of the present invention, when the spot diameter of the laser beam is D and the width of the gap to be welded between the first welded part and the second welded part is h, one or more of the following conditions are met:

[0052] D <L;

[0053] D+h / 2≤H≤D+h;

[0054] H <L。

[0055] In practice, the welding gun distance can be confirmed based on the standard focal length value of the laser welding head, and the laser beam spot diameter D at this gun distance can be confirmed. Under the above conditions, increasing H, that is, increasing the swing area, can improve the repair ability during the second welding, thereby improving the quality of welding. Still taking the swing trajectory as a rectangle as an example, when the gap to be welded passes through the short side of the rectangle for the first time and is welded at high temperature, if a welding defect occurs, due to the large swing area, there are more opportunities to repair the defect when the blast hole passes through the large swing area of ​​the rectangle. During the repair process, when the laser beam moves along the long side of the rectangle for welding, it melts the base material and covers the welding defect, so that the welding repair is performed when the gap to be welded passes through the short side perpendicular to its extension direction.

[0056] The present invention also provides a compressor in which at least two components are fixedly connected using the laser welding method. More specifically, the compressor includes an upper shell cover, a lower shell cover, and a housing; the upper shell cover and the housing, and the lower shell cover and the housing are fixedly connected using the laser welding method. Figures 4 to 7 This figure shows a schematic diagram of different stages of welding the shell cover and casing of a compressor using a laser welding method according to an embodiment of the present invention, where the shell cover is not distinguished as either the upper or lower shell cover. During welding, the laser beam irradiates an arbitrary point X in the gap to be welded, and then irradiates points A1 and A2 on the oscillation trajectory. The arbitrary point X receives the first weld at point A1 and the second weld at point A2. The dynamic laser needs to complete at least one irradiation heating of each of the two long sides of the quadrilateral. If the irradiation is performed more than once, the irradiation interval must be ≥ 0.01s, where 0.01s is the weld cooling time. The two long sides of the rectangle are repeatedly heated in the solid state. Repeated solid-state heating is more conducive to filling the gap to be welded and substantially completing the weld overlap, creating a zipper effect. To ensure a zipper-like welding effect, the speed of the dynamic laser beam should be neither too slow nor too fast. Preferably, the oscillation frequency in step S200 should be less than or equal to 100Hz. Since the long side of the rectangle is heated in the solid state, any point X passing through point A2 is in the solid state. Only in the solid state can the secondary welding repair effect be produced. Figure 7 .

[0057] When the oscillation trajectory has other shapes, the welding process is the same as above, but welding parameters such as the laser beam spot diameter, the movement speed of the first and second welded parts, and the oscillation frequency can be set to different values. For example, the laser beam spot diameter can be increased to expand the laser beam irradiation heating range. When the gap to be welded is large, the oscillation range of the oscillation trajectory can be increased. In the above example, the length of the first side length H is increased. Because the laser welding method of the present invention actually welds twice, and when welding along the second side length, the laser beam stirs and melts the base material, converging to fill and raise the weld, the width of the weldable gap can be effectively increased. Compared to the maximum 0.3mm gap to be welded in conventional laser welding, the width h of the weldable gap to be welded by the welding method of the present invention can reach 1.0mm. Therefore, this welding method is suitable for gaps to be welded with a width less than or equal to 1.0mm, which can effectively reduce the precision of the layout of the workpieces to be welded. At the same time, due to the reduced precision requirements of the above-mentioned gap to be welded, in some embodiments, the laser equipment does not need to be equipped with a front-end vision guidance system, and the dynamic laser zipper welding of the present invention can directly meet the welding requirements.

[0058] The welding of the compressor cover to the housing is circumferential, in which case the movement of the gap to be welded is rotational. The welding method of the present invention can also be applied to the welding of curved welds, straight welds, or irregular shapes composed thereof. In these cases, the movement of the gap to be welded, or the workpiece to be welded, is slightly different.

[0059] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0060] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A laser welding method, characterized in that: The welding method includes the following steps: S100: Set the laser beam trajectory and the moving speeds of the first welding part and the second welding part. The laser beam trajectory includes a swing trajectory and a swing frequency; S200: Arrange the first welding part and the second welding part. The swing trajectory has at least two intersection points with the welding gap between the first welding part and the second welding part; S300: Move the first welding part and the second welding part at the moving speeds, and start the laser beam to weld the first welding part and the second welding part along the laser beam trajectory.

2. The laser welding method according to claim 1, characterized in that: The swing trajectory is a combination of one or more of a polygon, a circle, and an ellipse.

3. The laser welding method according to claim 1, characterized in that: The swing trajectory is symmetric with respect to the welding gap.

4. The laser welding method according to claim 1, characterized in that: The swing trajectory is a quadrilateral; The spot diameter of the laser beam is D; The length of the first side of the quadrilateral along the direction perpendicular to the extension direction of the welding gap is H; The width of the welding gap between the first welding part and the second welding part is h, and it satisfies: D + h / 2 ≤ H ≤ D + h.

5. The laser welding method according to claim 4, characterized in that: The length of the second side of the quadrilateral along the extension direction of the welding gap is L, and it satisfies: D < L; or The length of the second side of the quadrilateral along the extension direction of the welding gap is L, and it satisfies: H < L.

6. The laser welding method according to claim 1, characterized in that: The swing frequency ≤ 100 Hz.

7. The laser welding method according to claim 1, characterized in that: The width of the welding gap between the first welding part and the second welding part is h, and the width h is less than or equal to 1.0 mm.

8. The laser welding method according to claim 1, characterized in that: The swing trajectory is realized by the swing of the galvanometer inside the laser welding head.

9. A compressor, characterized in that: The laser welding method according to any one of claims 1 to 8 is used for fixedly connecting at least two components of the compressor.

10. The compressor according to claim 9, characterized in that The compressor includes an upper shell cover, a lower shell cover, and a housing; The upper shell cover and the housing, and the lower shell cover and the housing are fixedly connected by the laser welding method.

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