Focal depth adjusting assembly, laser welding head and laser welding equipment

Abstract

The utility model provides a focal depth adjusting assembly, a laser welding head and laser welding equipment. The focal depth adjusting assembly comprises a first reflecting mirror, a second reflecting mirror, a third reflecting mirror and a fourth reflecting mirror which are arranged in a manner of forming an included angle of 45 degrees with the optical axis of the incident light beam; an incident light beam enters the first reflecting mirror, is reflected by the first reflecting mirror, the second reflecting mirror, the third reflecting mirror and the fourth reflecting mirror in sequence, is emitted from the fourth reflecting mirror, and is focused to form a focal point positioned on an optical axis; the first reflecting mirror and the fourth reflecting mirror are fixed relative to an incident light beam, the second reflecting mirror and the third reflecting mirror synchronously move in a reciprocating mode at a set frequency within a set range in the direction perpendicular to the optical axis, the focus moves back and forth on the optical axis, and when the movement speed of the focus reaches a high speed, the purpose of dynamically prolonging the focal depth can be achieved. The short-focal-length focusing lens has the advantages of a short-focal-length focusing lens and a long-focal-length focusing lens, and thermal influence and potential safety hazards caused by large laser energy of the long-focal-length focusing lens are overcome.

Description

Technical Field

[0001] The present application relates to the field of laser welding technology, and more specifically, to a focal depth adjustment component, a laser welding head, and laser welding equipment. Background Art

[0002] Laser welding is widely used in the lithium battery industry, and the quality of laser welding is particularly sensitive to changes in focal length. Factors such as inconsistent product height and focus shift of the lens in the laser welding head due to high temperature can cause inaccurate welding focal length and lead to cold welds, which directly affects product quality.

[0003] Conventional laser welding heads often use focusing lenses with longer focal depths, which results in consistent laser energy density within the focal depth, minimal changes in spot area, and minimal changes in energy density. This results in a more stable power density within the spot coverage area, reducing focus requirements and lowering the probability of surface deformation of the weld material and cold welds caused by welding highly reflective materials. However, the longer the focal depth of the focusing lens, the larger the spot size and the lower the energy density. Achieving the same welding standard requires greater laser energy, which in turn generates greater heat input and thermal impact, posing a safety hazard to the lithium battery cells being welded. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide a focal depth adjustment component, a laser welding head and a laser welding device to solve the technical problem in the related art that the laser welding head uses a longer focal depth and a larger laser energy to cause safety hazards to the lithium battery cells to be welded.

[0005] In a first aspect, an embodiment of the present application provides a depth of focus adjustment component, comprising a first reflector, a second reflector, a third reflector, and a fourth reflector, all of which are arranged at an angle of 45° to the optical axis of an incident light beam; after the incident light beam is incident on the first reflector, it is reflected in sequence by the first reflector, the second reflector, the third reflector, and the fourth reflector, and is focused to form a focus located on the optical axis after being emitted from the fourth reflector; the first reflector and the fourth reflector are fixed relative to the incident light beam, and the second reflector and the third reflector move back and forth synchronously within a predetermined range and at a predetermined frequency in a direction perpendicular to the optical axis, so that the focus moves back and forth on the optical axis.

[0006] In one embodiment, the predetermined frequency is 60 Hz to 120 Hz.

[0007] In one embodiment, the depth of focus adjustment assembly includes a box, a first support frame and a second support frame; the first reflector and the fourth reflector are installed on the first support frame, the second reflector and the third reflector are installed on the second support frame, the first support frame and the second support frame are both built into the box, the first support frame is fixed relative to the box, and the second support frame slides relative to the box in a direction perpendicular to the optical axis.

[0008] In one embodiment, a first light-transmitting hole and a second light-transmitting hole are respectively provided on two opposite sides of the box, the first light-transmitting hole corresponds to the first reflector, and the second light-transmitting hole corresponds to the fourth reflector. The incident light beam enters the interior of the box through the first light-transmitting hole, and after being reflected by the fourth reflector, it is emitted to the outside of the box through the second light-transmitting hole.

[0009] In one embodiment, the focal depth adjustment component includes a protective lens, and the first light-transmitting hole and the second light-transmitting hole are both provided with the protective lens.

[0010] In one embodiment, the depth of focus adjustment assembly includes a driving member and a transmission member connected between the driving member and the second support frame. The driving member is installed on the box body and drives the transmission member to drive the second support frame to slide relative to the box body.

[0011] In one embodiment, the driving member is a motor, and the transmission member includes an eccentric wheel, a connecting rod, a guide rod and a slider connected in sequence; the eccentric wheel is fixedly connected to the output shaft of the motor, and the connecting rod is rotatably connected to the eccentric wheel around a first rotating shaft, and the first rotating shaft is parallel to and spaced apart from the rotation center of the output shaft; the slider is fixedly connected to the box, the guide rod is slidably connected to the slider along a direction perpendicular to the optical axis, and the guide rod is fixedly connected to the second support frame.

[0012] In one embodiment, there are two guide rods, which are arranged in parallel and at intervals. The transmission member includes a connecting member, which is connected to the ends of the two guide rods away from the second support frame; the end of the connecting rod away from the eccentric wheel is rotatably connected to the connecting member around a second rotation axis, and the second rotation axis is parallel to the rotation center of the output shaft and is arranged at intervals in a direction perpendicular to the optical axis; the distance between the first rotation axis and the rotation center of the output shaft is d, and the predetermined range is 2d, wherein 0.5mm≤d≤1.5mm.

[0013] In a second aspect, an embodiment of the present application provides a laser welding head, comprising the above-mentioned focal depth adjustment assembly.

[0014] In a third aspect, an embodiment of the present application provides a laser welding device, comprising a laser welding head and the above-mentioned depth of focus adjustment component, wherein the depth of focus adjustment component is arranged corresponding to the light outlet of the laser welding head, and the laser beam emitted from the light outlet becomes the incident light beam incident on the depth of focus adjustment component.

[0015] The beneficial effect of the depth of focus adjustment assembly provided by the embodiment of the present application is that: compared with the related art, the depth of focus adjustment assembly of the present application, by causing the second reflector and the third reflector to move back and forth within a predetermined range at a predetermined frequency in a direction perpendicular to the optical axis, can make the focus move back and forth within a predetermined interval on the optical axis. When the movement speed of the focus reaches a high level, the purpose of dynamically extending the depth of focus can be achieved, thereby improving the tolerance for focal length during the welding process. In addition, the use of the above-mentioned depth of focus adjustment assembly can make the short-focal-length focusing mirror have the advantages of both short-focal-length focusing mirrors and long-focal-length focusing mirrors by dynamically extending the depth of focus, effectively improving welding stability and reducing the risk of cold welding. It can also overcome the thermal effects caused by the larger laser energy of the long-focal-length focusing mirror, thereby reducing the safety hazards caused to the lithium battery cells to be welded. Furthermore, a conventional laser welding head achieves focusing by changing the position of the focal point through longitudinal movement, while in the present application, the position of the focal point on the optical axis can be changed by synchronously moving the second reflector and the third reflector in a direction perpendicular to the optical axis. Although both the conventional scheme and the scheme of the present application can achieve the change of the position of the focal point, the moving inertia of the first reflector and the second reflector in the present application is smaller than the moving inertia of the laser welding head in the conventional scheme, so that the jitter is smaller, which can improve the welding stability and improve the welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 A schematic diagram of the appearance and structure of a depth of focus adjustment assembly provided in an embodiment of the present application;

[0018] Figure 2 for Figure 1 A cross-sectional view of the depth of focus adjustment assembly shown;

[0019] Figure 3 for Figure 2 A structural schematic diagram of the focus depth adjustment component from another perspective;

[0020] Figure 4 for Figure 2The schematic diagram of the structure of the depth of focus adjustment assembly shown is a one-view diagram after omitting the connecting rod, eccentric wheel and high-speed bearing;

[0021] Figure 5 for Figure 1 Schematic diagram of the optical path in the depth of focus adjustment component shown;

[0022] Figure 6 A schematic structural diagram of the laser welding equipment provided in an embodiment of the present application;

[0023] Among them, the reference numerals in the figures are:

[0024] 10. Depth of focus adjustment assembly; 11. First reflector; 12. Second reflector; 13. Third reflector; 14. Fourth reflector; 15. Box; 151. First light-transmitting hole; 16. First support frame; 17. Second support frame; 18. Protective lens; 19. Driving member; 191. Output shaft; 192. Rotation center; 21. Transmission member; 211. Eccentric wheel; 212. Connecting rod; 213. Guide rod; 214. Slider; 215. First rotating shaft; 216. Connecting member; 217. Second rotating shaft; 22. High-speed bearing; 23. Linear bearing; 30. Incident light beam; 31. Optical axis; 40. Laser welding equipment; 41. Laser welding head; 42. Driving assembly. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0026] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0029] Please also refer to Figures 1 to 5 The depth of focus adjustment assembly 10 provided in an embodiment of the present application will now be described. The depth of focus adjustment assembly 10 includes a first reflector 11, a second reflector 12, a third reflector 13, and a fourth reflector 14, all of which are arranged at a 45° angle with the optical axis 31 of the incident light beam 30. After the incident light beam 30 is incident on the first reflector 11, it is reflected by the first reflector 11, the second reflector 12, the third reflector 13, and the fourth reflector 14 in sequence, and is focused to form a focal point located on the optical axis 31 after being emitted from the fourth reflector 14. The first reflector 11 and the fourth reflector 14 are fixed relative to the incident light beam 30, and the second reflector 12 and the third reflector 13 move back and forth synchronously within a predetermined range and at a predetermined frequency in a direction perpendicular to the optical axis 31, so that the focal point moves back and forth on the optical axis 31.

[0030] like Figure 5 As shown, it can be understood that the reflective surface of the first reflector 11 faces the incident light beam 30 and is arranged at a 45° angle to the optical axis 31 of the incident light beam 30. The reflective surface of the fourth reflector 14 faces away from the incident light beam 30 and is arranged at a 45° angle to the optical axis 31 of the incident light beam 30. The reflective surface of the second reflector 12 faces the reflective surface of the first reflector 11, and the reflective surface of the second reflector 12 is arranged parallel to and spaced apart from the reflective surface of the first reflector 11. The reflective surface of the third reflector 13 faces the reflective surface of the fourth reflector 14, and the reflective surface of the third reflector 13 is arranged parallel to and spaced apart from the reflective surface of the fourth reflector 14. Therefore, the reflective surface of the third reflector 13 is opposite to the reflective surface of the second reflector 12 and forms a 90° angle. In this way, after the incident light beam 30 is irradiated by the reflective surface of the first reflector 11, it will be reflected by the reflective surfaces of the first reflector 11, the second reflector 12, the third reflector 13, and the fourth reflector 14 in sequence before being emitted.

[0031] It can be understood that in the direction perpendicular to the optical axis 31 (ie Figure 5When the second reflector 12 and the third reflector 13 are synchronously moved in the direction indicated by BB in the middle (in the direction indicated by BB in the middle) away from the first reflector 11 and the fourth reflector 14, the distance of the light beam between the four reflectors gradually increases, and the focus moves along the optical axis 31 and gradually approaches the fourth reflector 14. When the second reflector 12 and the third reflector 13 are synchronously moved in the direction perpendicular to the optical axis 31 and close to the first reflector 11 and the fourth reflector 14, the distance of the light beam between the four reflectors gradually shortens, and the focus moves along the optical axis 31 and gradually moves away from the fourth reflector 14.

[0032] like Figure 5 As shown, when the second reflector 12 and the third reflector 13 move synchronously from position D1 to position D2 along the BB direction, the focus moves from position C1 to position C2. Conversely, when the second reflector 12 and the third reflector 13 move synchronously from position D2 to position D1 along the BB direction, the focus moves from position C2 to position C1.

[0033] In the above-mentioned depth of focus adjustment assembly 10, by causing the second reflector 12 and the third reflector 13 to move back and forth within a predetermined range at a predetermined frequency in a direction perpendicular to the optical axis 31, the focus can be moved back and forth within a predetermined interval on the optical axis 31. When the movement speed of the focus reaches a high level, the purpose of dynamically extending the depth of focus can be achieved, thereby improving the tolerance for focal length during the welding process. In addition, the use of the above-mentioned depth of focus adjustment assembly 10 can enable a short-focal-length focusing mirror to have the advantages of both a short-focal-length focusing mirror and a long-focal-length focusing mirror by dynamically extending the depth of focus, effectively improving welding stability and reducing the risk of cold welding. It can also overcome the thermal effects caused by the larger laser energy of the long-focal-length focusing mirror, thereby reducing the safety hazards caused to the lithium battery cells to be welded. Furthermore, the conventional laser welding head 41 achieves focusing by changing the position of the focal point by moving longitudinally, while in the present application, the position of the focal point on the optical axis 31 can be changed by synchronously moving the second reflector 12 and the third reflector 13 in a direction perpendicular to the optical axis 31. Although both the conventional scheme and the scheme of the present application can achieve the change of the position of the focal point, the moving inertia of the first reflector 11 and the second reflector 12 in the present application is smaller than the moving inertia of the laser welding head 41 in the conventional scheme, so that the jitter is smaller, which can improve the welding stability and improve the welding quality.

[0034] Specifically, in this application, the predetermined frequency is 60 Hz to 120 Hz. By reciprocating the second reflector 12 and the third reflector 13 at a high frequency in a direction perpendicular to the optical axis 31, the focus can be moved back and forth at high speed on the optical axis 31, thereby dynamically extending the depth of focus during the welding process. It should be noted that the predetermined range of synchronous movement of the second reflector 12 and the third reflector 13 can be set based on the desired reciprocating range of the focus on the optical axis 31 during welding.

[0035] Combine Figures 1 to 4 As shown, in a specific embodiment of the present application, the depth of focus adjustment assembly 10 includes a box 15, a first support frame 16 and a second support frame 17, the first reflector 11 and the fourth reflector 14 are installed on the first support frame 16, the second reflector 12 and the third reflector 13 are installed on the second support frame 17, the first support frame 16 and the second support frame 17 are both built into the box 15, the first support frame 16 is fixed relative to the box 15, and the second support frame 17 slides relative to the box 15 in a direction perpendicular to the optical axis 31.

[0036] It can be understood that the first reflector 11 and the fourth reflector 14 are mounted on the first support frame 16 and are relatively fixed, while the second reflector 12 and the third reflector 13 are mounted on the second support frame 17 and are relatively fixed. The second reflector 12 and the third reflector 13 are driven to move synchronously by sliding the second support frame 17 relative to the box 15. Furthermore, the box 15 has a hollow structure. By embedding the first support frame 16 and the second support frame 17 into the box 15, each reflector is located inside the box 15. This allows the incident light beam 30 to be transmitted inside the box 15 after entering the box 15, and the box 15 can block the influence of external light on the incident light beam 30. In addition, the provision of the box 15 also helps to use the depth of focus adjustment assembly 10 as a complete module.

[0037] Furthermore, a first light-transmitting hole 151 and a second light-transmitting hole (not shown) are respectively provided on the two opposite sides of the box body 15. The first light-transmitting hole 151 corresponds to the first reflector 11, and the second light-transmitting hole corresponds to the fourth reflector 14. The incident light beam 30 enters the interior of the box body 15 through the first light-transmitting hole 151, and after being reflected by the fourth reflector 14, it is emitted to the outside of the box body 15 through the second light-transmitting hole.

[0038] The focus depth adjustment assembly 10 includes a protective lens 18, and both the first light transmission hole 151 and the second light transmission hole are provided with a protective lens 18. By providing the protective lens 18, the first light transmission hole 151 and the second light transmission hole can be blocked to prevent external clothing from entering the interior of the box 15 while allowing the light beam to pass through.

[0039] Continue to refer Figures 1 to 4 In the specific embodiment of the present application, the depth of focus adjustment assembly 10 includes a driving member 19 and a transmission member 21 connected between the driving member 19 and the second support frame 17. The driving member 19 is mounted on the housing 15 and drives the transmission member 21 to cause the second support frame 17 to slide relative to the housing 15. It can be understood that the driving member 19 drives the second support frame 17 to reciprocate through the motion transmitted by the transmission member 21.

[0040] Specifically, the driving member 19 is a motor, and the transmission member 21 includes an eccentric wheel 211, a connecting rod 212, a guide rod 213, and a slider 214 connected in sequence. The eccentric wheel 211 is fixedly connected to the output shaft 191 of the motor, and the connecting rod 212 is rotatably connected to the eccentric wheel 211 around a first rotating shaft 215. The first rotating shaft 215 is parallel to and spaced from the rotation center 192 of the output shaft 191. The slider 214 is fixedly connected to the housing 15. The guide rod 213 is slidably connected to the slider 214 in a direction perpendicular to the optical axis 31. The guide rod 213 is fixedly connected to the second support frame 17. When the output shaft 191 of the motor drives the eccentric wheel 211 to rotate, the eccentric wheel 211 drives the connecting rod 212 to oscillate, so that the connecting rod 212 drives the guide rod 213 to slide back and forth relative to the slider 214.

[0041] It can be understood that the connecting rod 212 and the eccentric wheel 211 are rotatably connected via the high-speed bearing 22. The high-speed bearing 22, with its higher speed, higher precision and higher wear resistance, can meet the requirement of the eccentric wheel 211 to rotate at high speed along with the output shaft 191 of the motor, so that the connecting rod 212 can make high-speed oscillating motion along with the rotation of the eccentric wheel 211, thereby enabling the second support frame 17 to drive the second reflector 12 and the third reflector 13 to move back and forth at a higher predetermined speed, thereby achieving the purpose of dynamically extending the focal depth.

[0042] It can be understood that the guide rod 213 and the slider 214 are connected by a linear bearing 23. The setting of the linear bearing 23 can not only meet the needs of the guide rod 213 sliding relative to the slider 214, but also reduce the movement friction resistance of the guide rod 213, and improve the smoothness of the movement of the guide rod 213, so that the first reflector 11 and the second reflector 12 have less jitter when moving back and forth, thereby improving the welding stability and welding quality.

[0043] Specifically, in the present application, there are two guide rods 213, which are arranged in parallel and spaced apart, and are both slidably connected to the slider 214. The transmission member 21 includes a connecting member 216, which is connected to the ends of the two guide rods 213 away from the second support frame 17. The end of the connecting rod 212 away from the eccentric wheel 211 is rotatably connected to the connecting member 216 about the second rotation axis 217, so that the connecting rod 212 reciprocates relative to the connecting member 216, and drives the connecting member 216, the two guide rods 213, and the second support frame 17 to reciprocate in a direction perpendicular to the optical axis 31.

[0044] Furthermore, the second rotation axis 217 is parallel to the rotation center 192 of the output shaft 191 and spaced apart in a direction perpendicular to the optical axis 31 (i.e., the sliding direction of the guide rod 213). The spacing between the first rotation axis 215 and the rotation center 192 of the output shaft 191 is d, and the predetermined range is 2d, where 0.5 mm ≤ d ≤ 1.5 mm. It will be appreciated that by arranging the second rotation axis 217 parallel to the rotation center 192 of the output shaft 191 and spaced apart in a direction perpendicular to the optical axis 31, the predetermined range can be maximized, i.e., 2d, while setting a smaller d. Furthermore, the predetermined range can be varied by varying the spacing d between the first rotation axis 215 and the rotation center 192 of the output shaft 191.

[0045] In the present application, d = 0.5 mm, so that the second support frame 17 drives the second reflector 12 and the third reflector 13 to reciprocate within a predetermined range of 2d = 1 mm, thereby achieving reciprocating movement of the focus within a range of 4 mm along the optical axis 31. In other embodiments, d can also be set to other values ​​such as 1 mm, 1.5 mm, and the predetermined range can be changed accordingly.

[0046] The present application also protects a laser welding head, which includes the aforementioned focus adjustment assembly 10. It is understood that the focus adjustment assembly 10 can be built into the laser welding head, thereby becoming a part of the laser welding head. As a result, when performing a welding operation, the laser welding head can change the position of the focus without having to move the entire head longitudinally. Instead, the focus position on the optical axis 31 can be changed simply by moving the second reflector 12 and the third reflector 13 in the focus adjustment assembly 10 in a direction perpendicular to the optical axis 31. This results in less inertia and less jitter, which can improve welding stability and weld quality.

[0047] like Figure 6 As shown, the present application also protects a laser welding device 40, which includes a laser welding head 41 and a focus adjustment assembly 10. The focus adjustment assembly 10 is arranged corresponding to the light outlet of the laser welding head 41. The laser beam emitted from the light outlet becomes the incident light beam 30 incident on the focus adjustment assembly 10. It is understood that the focus adjustment assembly 10 can be a device independent of the laser welding head 41. According to welding requirements, the focus adjustment assembly 10 can be installed in an external manner on the side of the light outlet of the laser welding head 41. Therefore, when the laser welding head 41 is stationary, the position of the focal point on the optical axis 31 can be changed by moving the second reflector 12 and the third reflector 13 in the focus adjustment assembly 10 in a direction perpendicular to the optical axis 31. In this way, the laser welding head 41, as a standard component, does not need to be modified, avoiding the risk of damage caused by modification of the laser welding head 41. Moreover, the focus adjustment assembly 10 can be used with various models of laser welding heads 41 to meet welding needs, and is simple and easy to install.

[0048] Specifically, the laser welding apparatus 40 includes a drive assembly 42 connected to a laser welding head 41 and capable of driving the laser welding head 41 in the X, Y, and Z axes, thereby allowing the laser welding head 41 to change its position relative to the workpiece being welded in three-dimensional space. Furthermore, a focus adjustment assembly 10 is connected to the laser welding head 41 so that it can move with the laser welding head 41 under the drive of the drive assembly 42.

[0049] Furthermore, the focus adjustment assembly 10 is slidably connected to the laser welding head 41 along the optical axis 31, so that the focus adjustment assembly 10 can slide relative to the laser welding head 41 along the optical axis 31 to change the distance between the two. In other embodiments, the focus adjustment assembly 10 can also be fixedly connected to the laser welding head 41.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A focal depth adjustment component, characterized in that: The optical axis of the incident light beam is formed by a first reflector, a second reflector, a third reflector, and a fourth reflector, each of which is arranged at an angle of 45° to the optical axis of the incident light beam. After the incident light beam is incident on the first reflector, it is reflected by the first reflector, the second reflector, the third reflector, and the fourth reflector in sequence, and is focused to form a focus on the optical axis after being emitted from the fourth reflector. The first reflector and the fourth reflector are fixed relative to the incident light beam, and the second reflector and the third reflector move back and forth synchronously at a predetermined frequency within a predetermined range in a direction perpendicular to the optical axis, so that the focus moves back and forth on the optical axis.

2. The focus depth adjustment assembly according to claim 1, characterized in that: The predetermined frequency is 60 Hz to 120 Hz.

3. The focus depth adjustment assembly according to claim 1, characterized in that: The depth of focus adjustment assembly includes a box, a first support frame and a second support frame; the first reflector and the fourth reflector are installed on the first support frame, the second reflector and the third reflector are installed on the second support frame, the first support frame and the second support frame are both built into the box, the first support frame is fixed relative to the box, and the second support frame slides relative to the box in a direction perpendicular to the optical axis.

4. The focus depth adjustment assembly according to claim 3, characterized in that: A first light-transmitting hole and a second light-transmitting hole are respectively provided on two opposite sides of the box, wherein the first light-transmitting hole corresponds to the first reflector, and the second light-transmitting hole corresponds to the fourth reflector. The incident light beam enters the interior of the box through the first light-transmitting hole, and after being reflected by the fourth reflector, is emitted to the outside of the box through the second light-transmitting hole.

5. The focus depth adjustment assembly according to claim 4, characterized in that: The focal depth adjustment component includes a protective lens, and the first light transmission hole and the second light transmission hole are both provided with the protective lens.

6. The focus depth adjustment assembly according to claim 3, characterized in that: The focal depth adjustment assembly includes a driving member and a transmission member connected between the driving member and the second support frame. The driving member is installed on the box body and drives the transmission member to drive the second support frame to slide relative to the box body.

7. The focus depth adjustment assembly according to claim 6, characterized in that: The driving member is a motor, and the transmission member includes an eccentric wheel, a connecting rod, a guide rod and a slider connected in sequence; the eccentric wheel is fixedly connected to the output shaft of the motor, and the connecting rod is rotatably connected to the eccentric wheel around a first rotating shaft, and the first rotating shaft is parallel to the rotation center of the output shaft and is spaced apart; the slider is fixedly connected to the box, and the guide rod is slidably connected to the slider along a direction perpendicular to the optical axis, and the guide rod is fixedly connected to the second support frame.

8. The focus depth adjustment assembly according to claim 7, characterized in that: There are two guide rods, which are arranged in parallel and at intervals. The transmission member includes a connecting member, which is connected to the end of the two guide rods away from the second support frame; the end of the connecting rod away from the eccentric wheel is rotatably connected to the connecting member around the second rotation axis, and the second rotation axis is parallel to the rotation center of the output shaft and is arranged at intervals in a direction perpendicular to the optical axis; the distance between the first rotation axis and the rotation center of the output shaft is d, and the predetermined range is 2d, wherein 0.5mm≤d≤1.5mm.

9. A laser welding head, characterized in that: The invention comprises the focus depth adjustment component according to any one of claims 1 to 8.

10. A laser welding device, characterized in that: It comprises a laser welding head and a focus depth adjustment assembly as described in any one of claims 1 to 8, wherein the focus depth adjustment assembly is arranged corresponding to the light outlet of the laser welding head, and the laser beam emitted from the light outlet becomes the incident light beam incident on the focus depth adjustment assembly.

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