A dual-focus laser welding optical system and optical welding head thereof

Abstract

The invention discloses a dual-focus laser welding optical system and its optical welding head. A dual-focus laser welding optical system includes a first lens group, a second lens group and a third lens group arranged in sequence along the incident direction of light; along the incident direction of light, the first lens group includes a first lens, a second lens and a third lens arranged in sequence, the second lens group includes a fourth lens, a fifth lens and a sixth lens arranged in sequence, and the third lens group includes a reflector and a plane protection window arranged in sequence; the first lens, the second lens, the fifth lens and the sixth lens are all positive lenses; the third lens is a negative lens, and the fourth lens is a wedge-shaped lens. The above welding optical system can form two focusing points with consistent energy on the surface of the workpiece, effectively improve the energy utilization rate, increase the welding molten width, improve the stability of the welding process, reduce spatter, improve the welding quality, and can meet various technical indicators of laser welding; and has a simple structure, convenient installation and debugging, and low cost.

Description

Technical Field

[0001] The invention relates to a dual-focus laser welding optical system and an optical welding head thereof, belonging to the field of laser welding. Background Art

[0002] Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. During laser welding, the laser is focused on the surface of the workpiece through optical elements such as focusing mirrors. The focusing characteristics of the laser, such as the roundness and energy distribution, directly affect the effect of laser welding. After the parallel laser is focused, the diameter of the laser focus spot is very small. When the laser deep-melt welds aluminum, there are many pores in the weld and the opening is small, so it is difficult for metal vapor to overflow, resulting in serious spatter. This problem can be solved by increasing the weld width. Usually in laser welding, the method of increasing the weld width is to reduce the welding speed or increase the defocus of the laser beam. Reducing the welding speed will prolong the welding time and affect the efficiency; increasing the defocus of the laser will cause the welding process to be unstable. In addition, precision welding must have a precise clamping device to keep the weld gap within a very small range, otherwise the laser may directly penetrate the weld or deviate from the weld, affecting the welding quality and causing undercutting of the weld. Summary of the invention

[0003] The present invention provides a dual-focus laser welding optical system and an optical welding head thereof, which can effectively increase the welding molten width, greatly reduce the pores in the weld, improve the welding quality, enhance the stability of the welding process, and effectively prevent the weld from biting.

[0004] In order to solve the above technical problems, the technical solutions adopted by the invention are as follows:

[0005] A dual-focus laser welding optical system comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the incident direction of light; along the incident direction of light, the first lens group comprises a first lens, a second lens and a third lens which are sequentially arranged, the second lens group comprises a fourth lens, a fifth lens and a sixth lens which are sequentially arranged, and the third lens group comprises a reflector and a plane protection window which are sequentially arranged; the first lens, the second lens, the fifth lens and the sixth lens are all positive lenses; the third lens is a negative lens, and the fourth lens is a wedge-shaped lens.

[0006] The above-mentioned dual-focus welding optical system is suitable for semiconductor lasers, YAG lasers and CO2 lasers, and the numerical aperture NA of the laser is about 0.1.

[0007] The divergent light from the laser is collimated into parallel light by the first lens, the second lens and the third lens in sequence, and is separated into two beams of consistent energy by the special-shaped wedge mirror, and then focused by the fifth lens and the sixth lens, and finally reflected on the working plane to form two focal points. The two focal points are separated by 1mm on the working plane, and the energy of the two focal spots is consistent. Both focal points are within the diffraction limit, and the circularity of the focused spot is above 98%.

[0008] In order to ensure that the focus spots are separated by 1 mm, the combined focal length of the first lens, the second lens and the third lens is in the range of 40 mm to 70 mm; the combined focal length of the fifth lens and the sixth lens is in the range of 60 mm to 100 mm.

[0009] The wedge angle of the wedge mirror is 1-3°, preferably 1.7°.

[0010] Along the incident direction of light, the two sides of the first lens are the first object side surface and the first image side surface, the two sides of the second lens are the second object side surface and the second image side surface, the two sides of the third lens are the third object side surface and the third image side surface, the two sides of the fourth lens are the fourth object side surface and the fourth image side surface, the two sides of the fifth lens are the fifth object side surface and the fifth image side surface, and the two sides of the sixth lens are the sixth object side surface and the sixth image side surface; in order to further improve the scanning stability and scanning efficiency, the first object side surface is a plane, and the radius of curvature of the first image side surface is 37.18 mm; the radius of curvature of the second object side surface is 109 mm, and the radius of curvature of the second image side surface is 76.8 mm; the radius of curvature of the third object side surface is 37 mm, and the radius of curvature of the third image side surface is -27 mm; the radius of curvature of the fifth object side surface is 81 mm, and the radius of curvature of the fifth image side surface is 420 mm; the radius of curvature of the sixth object side surface is 44 mm, and the radius of curvature of the sixth image side surface is -134 mm.

[0011] Both sides of the above-mentioned plane protection window are planes.

[0012] In order to further improve the uniformity of the two focal points, the fourth object side surface is a plane, and the fourth image side surface is beveled into a wedge shape from the center to form a wedge-shaped mirror, that is, half of the height in the height direction is beveled to form a wedge shape, and the wedge angle is preferably 1.7°. The thickness of the fourth lens that is not beveled is 5 mm.

[0013] In order to reduce energy loss and improve welding efficiency, the center distance between the first lens and the second lens is 3.5±0.05mm; the center distance between the second lens and the third lens is 0.5±0.05mm; the center distance between the third lens and the fourth lens is 10±0.05mm; the center distance between the fourth lens and the fifth lens is 2±0.05mm; and the center distance between the fifth lens and the sixth lens is 3±0.05mm.

[0014] In order to further improve the stability of welding, the center thickness of the first lens is 6±0.1mm; the center thickness of the second lens is 5±0.1mm; the center thickness of the third lens is 5±0.1mm; the center thickness of the fifth lens is 5±0.1mm; and the center thickness of the sixth lens is 5±0.1mm.

[0015] In order to meet the requirements of high-power laser welding, the materials of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the reflector and the plane protection window are all made of UV fused quartz.

[0016] A dual-focus laser welding head, comprising the dual-focus laser welding optical system, and also comprising a QBH joint, a first mirror seat, a second mirror seat and a third mirror seat connected in sequence;

[0017] The first lens, the second lens and the third lens are sequentially mounted in the first lens holder; a first spacer is provided between the first lens and the second lens, and a second spacer is provided between the second lens and the third lens; the object side surface of the first lens is fixed by a limiting step in the first lens holder; the image side surface of the third lens is fixed by a first transition ring and a first pressure ring sequentially connected to the third lens;

[0018] The second lens holder is provided with an adjustment ring on the outside and an inner lens barrel on the inside. The adjustment ring, the second lens holder and the inner lens barrel are fixed by guide pins to form a rotating barrel, and the rotating barrel can rotate relative to the first lens holder and the third lens holder; the fourth lens, the fifth lens and the sixth lens are sequentially installed in the inner lens barrel; a third spacer ring is provided between the fourth lens and the fifth lens; a fourth spacer ring is provided between the fifth lens and the sixth lens; the object side surface of the fourth lens is fixed by a second transition ring and a second pressure ring sequentially connected to the fourth lens; the image side surface of the sixth lens is fixed by a limiting step in the inner lens barrel;

[0019] The reflector is installed in the third mirror seat, and the reflective surface of the reflector forms an angle of 45° with the incident direction of light; the plane protection window is installed on the side wall of the third mirror seat on one side of the reflective surface of the reflector, and the plane protection window forms an angle of 90° with the incident direction of light.

[0020] The first lens holder, the second lens holder and the third lens holder are assembled to form a lens barrel, and the material used for each lens holder is aluminum; the center deviation of the lens barrel must be guaranteed to be less than 1'.

[0021] Rotate the rotating cylinder to realize the rotation of the wedge mirror and the focusing mirror, and then adjust the position of the dual focus relative to the welding point to improve the accuracy; rotate the rotating cylinder, and also change the working mode of the dual focus welding head, for example, the center line of the two foci is parallel or perpendicular to the welding direction.

[0022] The above-mentioned dual-focus welding head can be used to weld metals and other materials, improve welding stability, reduce spatter, and meet various technical indicators of laser welding.

[0023] The technologies not mentioned in the present invention are all referred to the prior art.

[0024] The dual-focus laser welding optical system of the present invention focuses a laser beam onto the workpiece surface through a focusing head to form two focal points. The two focal points are separated by 1 mm on the working plane and have consistent energy, which effectively improves energy utilization, increases welding melt width, improves the stability of the welding process, reduces spatter, improves welding quality, can meet various technical indicators of laser welding, and can be applied to welding metals and other materials; and has a simple structure, is easy to install and debug, and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is an optical system diagram of the dual-focus laser welding optical system of the present invention;

[0026] Figure 2 The focus energy distribution of the dual-focus laser welding optical system of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the dual-focus laser welding head of the present invention;

[0028] Figure 4 This is a working diagram of the dual-focus laser welding head of the present invention;

[0029] In the figure, 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the fourth lens, 5 is the fifth lens, 6 is the sixth lens, 7 is the reflector, 8 is the plane protection window, 9 is the QBH connector, 10 is the first spacer, 11 is the second spacer, 12 is the first transition ring, 13 is the first pressure ring, 14 is the second lens seat, 15 is the adjustment ring, 16 is the second pressure ring, 17 is the second transition ring, 18 is the third spacer, 19 is the fourth spacer, 20 is the inner lens barrel, 21 is the third lens seat, and 22 is the first lens seat. DETAILED DESCRIPTION

[0030] In order to better understand the invention, the content of the invention is further explained below in conjunction with the embodiments, but the content of the invention is not limited to the following embodiments.

[0031] Example 1

[0032] like Figure 1As shown, a dual-focus laser welding optical system comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the incident direction of light; along the incident direction of light, the first lens group comprises a first lens, a second lens and a third lens which are sequentially arranged, the second lens group comprises a fourth lens, a fifth lens and a sixth lens which are sequentially arranged, and the third lens group comprises a reflector and a plane protective window which are sequentially arranged; the first lens, the second lens, the fifth lens and the sixth lens are all positive lenses; the third lens is a negative lens, and the fourth lens is a wedge-shaped lens; the materials of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the reflector and the plane protective window are all ultraviolet fused quartz.

[0033] The center thickness of the first lens is 6mm; the center thickness of the second lens is 5mm; the center thickness of the third lens is 5mm; the center thickness of the fifth lens is 5mm; the center thickness of the sixth lens is 5mm; the center distance between the first lens and the second lens is 3.5mm; the center distance between the second lens and the third lens is 0.5mm; the center distance between the third lens and the fourth lens is 10mm; the center distance between the fourth lens and the fifth lens is 2mm; the center distance between the fifth lens and the sixth lens is 3mm.

[0034] Along the incident direction of light, the two sides of the first lens are the first object side surface and the first image side surface, the two sides of the second lens are the second object side surface and the second image side surface, the two sides of the third lens are the third object side surface and the third image side surface, the two sides of the fourth lens are the fourth object side surface and the fourth image side surface, the two sides of the fifth lens are the fifth object side surface and the fifth image side surface, and the two sides of the sixth lens are the sixth object side surface and the sixth image side surface; the first object side surface is a plane, and the curvature radius of the first image side surface is 37.18mm; the curvature radius of the second object side surface is 109mm, and the curvature radius of the second image side surface is 16.8mm. The radius of curvature of the side is 76.8mm; the radius of curvature of the third object side is 37mm, and the radius of curvature of the third image side is -27mm; the fourth object side is a plane, and the fourth image side is beveled from the center to form a wedge-shaped lens (that is, half of the height in the height direction is beveled to form a wedge), the wedge angle is 2°, and the thickness of the fourth lens that is not beveled is 5mm; the radius of curvature of the fifth object side is 81mm, and the radius of curvature of the fifth image side is 420mm; the radius of curvature of the sixth object side is 44mm, and the radius of curvature of the sixth image side is -134mm. The combined focal length of the first lens, the second lens, and the third lens is 50mm; the combined focal length of the fifth lens and the sixth lens is 75mm.

[0035] like Figure 2As shown in the figure, the divergent light from the laser is collimated into parallel light by the first lens, the second lens and the third lens in sequence, separated into two beams of consistent energy by the special-shaped wedge mirror, and then focused by the fifth lens and the sixth lens, and finally reflected on the working plane to form two focal points. The two focal points are separated by 1mm on the working plane, and the energy of the two focal spots is consistent. Figure 2 It can be seen that both focal points are within the diffraction limit, and the circularity of the focused spot is more than 98%. By rotating the wedge mirror, the position of the dual focal points relative to the welding point can be adjusted to improve the accuracy, such as Figure 4 The rotating wedge mirror can also change the working mode of the dual-focus welding head, for example, the center line of the two foci is parallel or perpendicular to the welding direction.

[0036] Example 2

[0037] like Figure 3 As shown, a dual-focus laser welding head includes the dual-focus laser welding optical system described in Example 1, and also includes a QBH joint, a first mirror seat, a second mirror seat and a third mirror seat connected in sequence;

[0038] The first lens, the second lens and the third lens are sequentially mounted in the first lens holder; a first spacer is provided between the first lens and the second lens, and a second spacer is provided between the second lens and the third lens; the object side surface of the first lens is fixed by a limiting step in the first lens holder; the image side surface of the third lens is fixed by a first transition ring and a first pressure ring sequentially connected to the third lens;

[0039] The second lens holder is provided with an adjustment ring on the outside and an inner lens barrel on the inside. The adjustment ring, the second lens holder and the inner lens barrel are fixed by guide pins to form a rotating barrel, and the rotating barrel can rotate relative to the first lens holder and the third lens holder; the fourth lens, the fifth lens and the sixth lens are sequentially installed in the inner lens barrel; a third spacer ring is provided between the fourth lens and the fifth lens; a fourth spacer ring is provided between the fifth lens and the sixth lens; the object side surface of the fourth lens is fixed by a second transition ring and a second pressure ring sequentially connected to the fourth lens; the image side surface of the sixth lens is fixed by a limiting step in the inner lens barrel;

[0040] The reflector is installed in the third mirror seat, and the reflective surface of the reflector forms an angle of 45° with the incident direction of light; the plane protection window is installed on the side wall of the third mirror seat on one side of the reflective surface of the reflector, and the plane protection window forms an angle of 90° with the incident direction of light.

[0041] The first lens holder, the second lens holder and the third lens holder are assembled to form a lens barrel, and the material used for each lens holder is aluminum; the center deviation of the lens barrel must be guaranteed to be less than 1'.

[0042] Rotate the rotating cylinder to realize the rotation of the wedge mirror and the focusing mirror, and then adjust the position of the dual focus relative to the welding point to improve the accuracy; rotate the rotating cylinder, and also change the working mode of the dual focus welding head, such as Figure 4 , the center line of the two foci is parallel or perpendicular to the welding direction.

[0043] Through practice, the above-mentioned dual-focus welding head can be used to weld metals and other materials, improve welding stability, reduce spatter, meet various technical indicators of laser welding, and has a simple structure, easy installation and debugging, and low cost.

Claims

1. A dual-focus laser welding optical system, characterized in that: The invention comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the incident direction of light; along the incident direction of light, the first lens group comprises a first lens, a second lens and a third lens which are sequentially arranged, the second lens group comprises a fourth lens, a fifth lens and a sixth lens which are sequentially arranged, and the third lens group comprises a reflector and a plane protection window which are sequentially arranged; the first lens, the second lens, the fifth lens and the sixth lens are all positive lenses; the third lens is a negative lens, and the fourth lens is a wedge-shaped lens; The combined focal length of the first lens, the second lens and the third lens is between 40mm and 70mm; the combined focal length of the fifth lens and the sixth lens is between 60mm and 100mm; The wedge angle of the wedge mirror is 1°~3°; Along the incident direction of light, the two sides of the first lens are the first object side surface and the first image side surface, the two sides of the second lens are the second object side surface and the second image side surface, the two sides of the third lens are the third object side surface and the third image side surface, the two sides of the fourth lens are the fourth object side surface and the fourth image side surface, the two sides of the fifth lens are the fifth object side surface and the fifth image side surface, and the two sides of the sixth lens are the sixth object side surface and the sixth image side surface; the first object side surface is a plane, and the radius of curvature of the first image side surface is 37.18 mm; the radius of curvature of the second object side surface is 109 mm, and the radius of curvature of the second image side surface is 76.8 mm; the radius of curvature of the third object side surface is 37 mm, and the radius of curvature of the third image side surface is -27 mm; the radius of curvature of the fifth object side surface is 81 mm, and the radius of curvature of the fifth image side surface is 420 mm; the radius of curvature of the sixth object side surface is 44 mm, and the radius of curvature of the sixth image side surface is -134 mm; The fourth object side is a plane, the fourth image side is beveled from the center into a wedge shape to form a wedge lens, the wedge angle is 1.7°, and the thickness of the fourth lens without beveling is 5±0.2mm; The center distance between the first lens and the second lens is 3.5±0.05mm; the center distance between the second lens and the third lens is 0.5±0.05mm; the center distance between the third lens and the fourth lens is 10±0.05mm; the center distance between the fourth lens and the fifth lens is 2±0.05mm; the center distance between the fifth lens and the sixth lens is 3±0.05mm; The center thickness of the first lens is 6±0.1 mm; the center thickness of the second lens is 5±0.1 mm; the center thickness of the third lens is 5±0.1 mm; the center thickness of the fifth lens is 5±0.1 mm; and the center thickness of the sixth lens is 5±0.1 mm.

2. The dual-focus laser welding optical system according to claim 1, characterized in that: The materials of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the reflector and the plane protection window are all UV fused quartz.

3. A dual-focus laser welding head, comprising the dual-focus laser welding optical system according to claim 1 or 2, characterized in that: It also includes a QBH connector, a first mirror mount, a second mirror mount and a third mirror mount which are connected in sequence; The first lens, the second lens and the third lens are sequentially mounted in the first lens holder; a first spacer is provided between the first lens and the second lens, and a second spacer is provided between the second lens and the third lens; the object side surface of the first lens is fixed by a limiting step in the first lens holder; the image side surface of the third lens is fixed by a first transition ring and a first pressure ring sequentially connected to the third lens; The second lens holder is provided with an adjustment ring on the outside and an inner lens barrel on the inside. The adjustment ring, the second lens holder and the inner lens barrel are fixed by guide pins to form a rotating barrel, and the rotating barrel can rotate relative to the first lens holder and the third lens holder; the fourth lens, the fifth lens and the sixth lens are sequentially installed in the inner lens barrel; a third spacer ring is provided between the fourth lens and the fifth lens; a fourth spacer ring is provided between the fifth lens and the sixth lens; the object side surface of the fourth lens is fixed by a second transition ring and a second pressure ring sequentially connected to the fourth lens; the image side surface of the sixth lens is fixed by a limiting step in the inner lens barrel; The reflector is installed in the third mirror seat, and the reflective surface of the reflector forms an angle of 45° with the incident direction of light; the plane protection window is installed on the side wall of the third mirror seat on one side of the reflective surface of the reflector, and the plane protection window forms an angle of 90° with the incident direction of light.

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