Split image focusing laser welding apparatus and laser welding method

Abstract

The application relates to a laser welding device with split image focusing, comprising: a laser welding head for welding a workpiece to form a weld; a first beam splitter for splitting light reflected by the workpiece into two parts; a split image focusing screen for receiving and transmitting part of the light split by the first beam splitter; a first imaging module for receiving the light transmitted by the split image focusing screen to collect a first image, the first image being a split image of the weld on the workpiece, for judging whether focusing is achieved; and a second imaging module for receiving the other part of the light split by the first beam splitter to collect a second image, the second image being an image of the weld on the workpiece and a laser focus point emitted by the laser welding head. The application also relates to a laser welding method. The laser welding device has the advantages of convenient focusing, high measurement precision and harmlessness to human eyes.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to a split-image focusing laser welding apparatus and a laser welding method. Background Technology

[0002] Laser welding technology, due to its advantages of stable welding, high pass rate, aesthetically pleasing results, fast welding speed, and less pollution, is increasingly used and popularized in fields such as nuclear power engineering. With the development of laser welding processes, various industries are placing higher demands on laser welding technology and quality. When using robots for laser welding, the focal distance cannot be automatically determined, while manual welding lacks stability. The existing manual focusing method used in laser welding has the following drawbacks: 1. The laser welding head emits a laser beam towards the workpiece to form the laser focal point, which can only be focused by direct visual observation, making it impossible to accurately measure the focal point position; 2. Prolonged direct viewing of the laser focal point can cause irreversible eye damage. Summary of the Invention

[0003] In order to overcome at least one of the disadvantages of the prior art, the present invention provides a laser welding device with split-image focusing, which has the advantages of convenient focusing, high measurement accuracy and no harm to the human eye.

[0004] The technical solution adopted in this invention is as follows:

[0005] A split-image focusing laser welding apparatus, comprising:

[0006] A laser welding head is used to emit a laser beam onto a workpiece through its emission port to weld the workpiece and form a weld. The light reflected from the workpiece enters the laser welding device through the emission port.

[0007] The first beam splitter is used to split the light reflected from the workpiece into two parts;

[0008] A split-image focusing screen is used to receive and transmit a portion of the light split by the first beam splitter.

[0009] The first imaging module is used to receive light transmitted through the split-image focusing screen to acquire a first image, which is a split-image image of the weld on the workpiece, and is used to determine whether the focus has been achieved.

[0010] The second imaging module is used to receive another portion of the light split off by the first beam splitter to acquire a second image, which is an image of the weld seam on the workpiece and the laser focus emitted by the laser welding head.

[0011] More preferably, the laser welding head includes a laser fiber and a second beam splitter, the second beam splitter being used to reflect the laser emitted by the laser fiber onto the workpiece and to transmit the light reflected by the workpiece to the first beam splitter.

[0012] More preferably, the laser welding head further includes a laser reflector, which is used to reflect the laser emitted by the laser fiber to the second beam splitter; the center lines of the emission port of the laser welding head, the second beam splitter, the first beam splitter, and the second imaging module are all on the same straight line.

[0013] More preferably, both the first imaging module and the second imaging module are CCD cameras; the center distance between the first beam splitter and the split-image focusing screen, the center distance between the split-image focusing screen and the first imaging module, and the center distance between the first beam splitter and the second imaging module are all equal.

[0014] More preferably, the laser welding device further includes a steering mirror disposed between the split-image focusing screen and the first imaging module. The steering mirror is any one of a pentaprism, a pentamirror, and a reflector, used to transmit the light transmitted through the split-image focusing screen to the first imaging module.

[0015] More preferably, the laser welding apparatus further includes a monitor, which is connected to the first imaging module and the second imaging module respectively, and the first image and the second image are displayed on the monitor respectively.

[0016] More preferably, the monitor is provided with crosshairs to indicate the center of the weld in the second image.

[0017] More preferably, the laser welding apparatus includes a control system for controlling the movement of the laser welding head.

[0018] More preferably, the emission port of the laser welding head is provided with a lens with a magnesium fluoride coating.

[0019] The present invention also provides a laser welding method using the laser welding apparatus described above, comprising the following steps:

[0020] The focus is determined by manually observing the first image. The method is as follows: if the welds on both sides of the first image are aligned, it indicates that the focus has been achieved; otherwise, it indicates that the focus has not been achieved.

[0021] If the result indicates that the focus has not been achieved, adjust the distance between the laser welding head and the workpiece until the focus is achieved;

[0022] The workpiece is welded using a laser welding head. The positional relationship between the weld seam and the laser focus on the workpiece is monitored in real time by manually observing a second image, so as to adjust the position of the laser welding head.

[0023] The present invention has the following beneficial effects:

[0024] 1. Based on the split-image focusing principle and utilizing optical reflection imaging, a first beam splitter is installed in the laser welding device to split the light reflected from the workpiece into two paths, which enter the first imaging module and the second imaging module respectively. The first imaging module, in conjunction with the split-image focusing screen, achieves the focusing function, while the second imaging module displays the complete weld seam in real time. Thus, the operator can determine whether focus has been achieved by observing the first image, and simultaneously monitor the formation of the weld seam during laser welding by observing the second image. This eliminates the need for direct human observation of the laser focus and weld seam on the workpiece, avoiding eye damage from prolonged direct laser viewing.

[0025] 2. A second beam splitter is set to reflect the laser onto the workpiece and transmit visible and infrared light onto the first beam splitter to form the first and second images. This protects the first and second imaging modules (CCD sensors) while allowing them to image normally without red light interference.

[0026] 3. By utilizing optical reflection imaging, the accuracy of laser welding head positioning can be ensured, thereby improving weld quality.

[0027] 4. Laser welding equipment can be applied to robotic laser welding, mainly based on programming and positioning. It uses split-image focusing combined with CCD camera imaging device to assist positioning, achieve distance compensation, simplify the operation of manual distance based on sense, and help achieve higher programming efficiency and higher weld quality.

[0028] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the laser welding apparatus for split-image focusing according to a preferred embodiment of the present invention;

[0030] Figure 2 for Figure 1 Optical path layout diagram in a laser welding device;

[0031] Figures 3A to 3B This diagram illustrates the monitor display when the laser welding head is at different height positions. In each diagram, the left side shows the first image, and the right side shows the second image. Figure 3A This indicates positive defocus (L < f). Figure 3B This indicates negative defocus (L > f). Figure 3C This indicates focusing (L = f).

[0032] Reference numerals: 1. Laser welding head; 11. Laser fiber; 12. Second beam splitter; 13. Laser reflector; 14. Emission port; 10. Laser head housing; 100. Laser focus; 20. Housing; 21. First beam splitter; 22. Split-image focusing screen; 23. Steering mirror; 31. First imaging module; 32. Second imaging module. Detailed Implementation

[0033] In the description of this invention, it should be noted that the directional terms such as "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0034] Furthermore, terms such as "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 technical features. Therefore, the use of terms such as "first" and "second" may explicitly or implicitly include one or more of those features.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] Please see Figure 1 and Figure 2 , Figure 1 and Figure 2 A laser welding apparatus for split-image focusing and its internal optical path according to a preferred embodiment of the present invention are shown, comprising:

[0037] Laser welding head 1 is used to emit a laser beam through its emission port 14 onto a workpiece (not shown) to perform welding processing on the joint of the workpiece to form a weld. The light reflected by the workpiece enters the laser welding device through the emission port 14.

[0038] The first beam splitter 21 is used to split the light reflected from the workpiece into two parts;

[0039] The split-image focusing screen 22 is used to receive and transmit a portion of the light split off by the first beam splitter 21;

[0040] The first imaging module 31 is used to receive the light transmitted through the split-image focusing screen 22 to acquire a first image, which is a split-image image of the weld on the workpiece, and is used to determine whether the focus has been achieved.

[0041] A steering mirror 23 is disposed between the split-image focusing screen 22 and the first imaging module 31, and is used to transmit the light transmitted through the split-image focusing screen 22 to the first imaging module 31.

[0042] The second imaging module 32 is used to receive another part of the light split off by the first beam splitter 21 to acquire a second image, which is an image of the weld on the workpiece and the laser focus 100 emitted by the laser welding head 1.

[0043] A monitor (not shown) is connected to the first imaging module 31 and the second imaging module 32 respectively, and is used to display the first image and the second image respectively;

[0044] The control system (not shown) is connected to the first imaging module 31, the second imaging module 32 and the laser welding head 1 respectively, and can also be connected to the monitor. The control system can control and adjust the position and movement path of the laser welding head 1 according to the image information collected by the first imaging module 31 and the second imaging module 32.

[0045] The outer casing 20 has a mirror cavity inside for installing components such as the first beam splitter 21, the split-image focusing screen 22, and the steering mirror 23. The outer casing 20 also assembles the laser welding head 1, the first imaging module 31, and the second imaging module 32 together.

[0046] Specifically, the laser welding head 1 includes:

[0047] Laser fiber 11 is used to generate laser light;

[0048] The second beam splitter 12 is used to reflect the laser generated by the laser fiber 11 onto the workpiece and transmit the light reflected by the workpiece to the first beam splitter 21.

[0049] A laser reflector 13 is disposed between the emitting end of the laser fiber 11 and the second beam splitter 12, and is used to reflect the laser emitted by the laser fiber 11 to the second beam splitter 12.

[0050] The emission port 14 allows the laser reflected by the second beam splitter 12 to pass through, and is used to emit the laser onto the workpiece to perform welding operations.

[0051] The laser head housing 10 has an internal mirror cavity for mounting the second beam splitter 12 and the laser reflector 13. The laser head housing 10 is assembled with the housing 20 and is internally connected to realize the assembly of various components and the arrangement of optical paths.

[0052] Preferably, the center lines of the laser welding head 1's emission port 14, the second beam splitter 12, the first beam splitter 21, and the second imaging module 32 are all on the same straight line, such as... Figure 2 As shown.

[0053] Preferably, the emission port 14 of the laser welding head 1 is provided with a lens with a magnesium fluoride (MgF) coating, which is an NC protective filter (neutral density filter).

[0054] The laser reflector 13 and the second beam splitter 12 are pressed and fixed in the mirror cavity of the laser head housing 10 by a fixing frame. The lens with magnesium fluoride coating is connected to the emission port 14 of the laser head housing 10 by a lens holder and bolts.

[0055] The light transmitted from the second beam splitter 12 to the first beam splitter 21 (i.e., the light reflected from the workpiece) includes visible light and infrared light, which will not cause stimulation or damage to the human eye when used for imaging.

[0056] Specifically, the first beam splitter 21 is used to split the light transmitted by the second beam splitter 12 into two parts. One part is reflected onto the split-image focusing screen 22 and then transmitted to the objective lens of the first imaging module 31 by the steering mirror 23 to form a first image for determining whether focus has been achieved. The other part is transmitted to the objective lens of the second imaging module 32 to form a second image for real-time display including the weld seam and the laser focus 100.

[0057] Preferably, both the first imaging module 31 and the second imaging module 32 are CCD cameras, namely the first CCD camera and the second CCD camera, and each has a corresponding CCD sensor. The first CCD camera is equipped with a 35mm macro light-transmitting window.

[0058] The center distance between the first beam splitter 21 and the split-image focusing screen 22, the center distance between the split-image focusing screen 22 and the first imaging module 31 (the CCD sensor of the first CC camera), and the center distance between the first beam splitter 21 and the second imaging module 32 (the CCD sensor of the second CC camera) are all equal.

[0059] As is known in the art, the split-image focusing screen 22 (split-image screen) is generally provided with two opposing optical wedges. When focusing is achieved, the images on both sides of the junction of the two optical wedges will merge completely, while when focusing is not achieved, the images on both sides of the junction of the two optical wedges will be misaligned.

[0060] The split-image focusing screen 22 is specifically a wedge mirror split-image frosted focusing screen.

[0061] The steering mirror 23 is any one of a pentaprism, a pentamirror, and a reflecting mirror, used to correct the image imaging direction, preferably a pentaprism, such as... Figure 1 and Figure 2 As shown. Compared to a pentaprism, a pentamirror is cheaper, but it suffers from light loss, resulting in a slightly darker image compared to a pentaprism. If the turning mirror 23 is a reflecting mirror, then... Figure 1-2 In contrast, the mounting position of the first imaging module 31 (first CCD camera) needs to be rotated 180° vertically.

[0062] The steering mirror 23 is glued to the mirror cavity of the housing 20. The inner wall of the mirror cavity where it is located is painted black to effectively prevent reflection interference.

[0063] The first imaging module 31 and the second imaging module 32 (the first CCD camera and the second CCD camera) are respectively installed into the housing 20 through threaded connections between the front end and the rear end of their light-transmitting windows.

[0064] The split-image focusing screen 22 is pressed together with the steering mirror 23 by an elastic spring.

[0065] like Figures 3A to 3C As shown, the monitor includes a split-image focusing indicator (left side) and a weld center auxiliary indicator (right side) located on both sides. The split-image focusing indicator (left side) displays a first image, and the weld center auxiliary indicator (right side) displays a second image. Both indicators are equipped with crosshairs to assist the human eye in observing the weld in the first and second images. The weld center auxiliary indicator (right side) is used to indicate the center of the weld in the second image.

[0066] like Figure 2 As shown, the optical path arrangement of the laser welding device is as follows:

[0067] The laser's optical path is as follows: laser fiber 11 → laser reflector 13 → second beam splitter 12 → emission port 14 → laser focus 100 on the workpiece.

[0068] The optical paths for visible and infrared light are: workpiece → second beam splitter 12 → first beam splitter 21. The first beam splitter 21 splits the received light into two paths, including:

[0069] (1) First beam splitter 21 → Split-image focusing screen 22 → Turning mirror 23 → First imaging module 31 (first CCD camera)

[0070] →First image;

[0071] (2) First beam splitter 21 → Second imaging module 32 (second CCD camera) → Second image.

[0072] In this embodiment, the workpiece to be welded is located directly below the laser welding head 1.

[0073] The center lines of the laser welding head 1's emission port 14, the second beam splitter 12, the first beam splitter 21, and the second imaging module 32 are all straight lines in the vertical direction.

[0074] The center line connecting the laser reflector 13 and the second beam splitter 12 of the laser welding head 1 is a straight line in the horizontal direction. The center line connecting the first beam splitter 21 and the split-image focusing screen 22 is a straight line in the horizontal direction.

[0075] The laser welding method using the laser welding apparatus includes the following steps:

[0076] The focus is determined by manually observing the first image. The method is as follows: if the welds on both sides of the first image are aligned, it indicates that the focus has been achieved; otherwise, it indicates that the focus has not been achieved.

[0077] If the result indicates that the focus has not been achieved, adjust the distance between the laser welding head 1 and the workpiece until the focus is achieved;

[0078] The workpiece is welded using laser welding head 1. The positional relationship between the weld seam on the workpiece and the laser focus 100 is monitored in real time by manually observing the second image, so as to adjust the position of laser welding head 1.

[0079] like Figure 3A and Figure 3B As shown, when the image is out of focus (in a positive or negative defocus state), the weld seams on both sides of the intersection of the two optical wedges in the first image on the left are broken and misaligned, indicating that the image is out of focus. Simultaneously, the weld seams in both the first image on the left and the second image on the right are relatively blurry and blurred. Figure 3C As shown, when the focus is achieved (in the focused state), the welds on both sides of the intersection of the two optical wedges in the first image on the left meet each other to form a straight line, and the welds in the first and second images are very clear.

[0080] When the operator observes on the monitor as follows Figure 3A or Figure 3B When the first image is on the left, the position of the laser welding head 1 is adjusted up and down so that the welds on both sides of the junction of the two optical wedges in the first image move closer to the center until the welds on both sides are joined to form a straight line. This indicates that accurate focus has been achieved, and the welds in the first and second images are the clearest. At this time, the effect of laser welding is also the most ideal.

[0081] The monitor can simultaneously display a first image and a second image. The first image displays the crack image of the weld seam to determine whether the focus has been achieved. The second image displays the laser focus 100 and the weld seam. The monitor screen is equipped with a crosshair center auxiliary line to help indicate the position of the laser focus 100 and the center of the weld seam, making it convenient for operators to achieve three-dimensional coordinate center focus and timely correct the midpoint of the welding laser head path.

[0082] The laser welding device of the present invention can be applied to robotic laser welding. It mainly focuses on programming positioning and uses split-image focusing combined with CCD camera imaging device to assist positioning, realize distance compensation, simplify the operation of manual distance by feeling, and help to achieve higher programming efficiency and higher weld quality.

[0083] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A laser welding apparatus for split-image focusing, characterized in that, include: A laser welding head is used to emit a laser beam onto a workpiece through its emission port to weld the workpiece and form a weld. The light reflected from the workpiece enters the laser welding device through the emission port. The first beam splitter is used to split the light reflected from the workpiece into two parts; A split-image focusing screen is used to receive and transmit a portion of the light split by the first beam splitter. The first imaging module is used to receive light transmitted through the split-image focusing screen to acquire a first image, which is a split-image image of the weld on the workpiece, and is used to determine whether the focus has been achieved. The second imaging module is used to receive another portion of the light split off by the first beam splitter to acquire a second image, which is an image of the weld seam on the workpiece and the laser focus emitted by the laser welding head.

2. The laser welding apparatus for split-image focusing according to claim 1, characterized in that, The laser welding head includes a laser fiber and a second beam splitter. The second beam splitter is used to reflect the laser generated by the laser fiber onto the workpiece and transmit the light reflected from the workpiece to the first beam splitter.

3. The laser welding apparatus for split-image focusing according to claim 2, characterized in that, The laser welding head also includes a laser reflector, which is used to reflect the laser emitted by the laser fiber to the second beam splitter; the center lines of the emission port of the laser welding head, the second beam splitter, the first beam splitter, and the second imaging module are all on the same straight line.

4. The laser welding apparatus for split-image focusing according to claim 1, characterized in that, Both the first imaging module and the second imaging module are CCD cameras; the center distance between the first beam splitter and the split-image focusing screen, the center distance between the split-image focusing screen and the first imaging module, and the center distance between the first beam splitter and the second imaging module are all equal.

5. The laser welding apparatus for split-image focusing according to claim 1, characterized in that, It also includes a steering mirror disposed between the split-image focusing screen and the first imaging module. The steering mirror is any one of a pentaprism, a pentamirror, and a reflector, and is used to transmit the light transmitted through the split-image focusing screen to the first imaging module.

6. The laser welding apparatus for split-image focusing according to claim 5, characterized in that, It also includes a monitor, which is connected to the first imaging module and the second imaging module respectively, and the first image and the second image are displayed on the monitor respectively.

7. The laser welding apparatus for split-image focusing according to claim 6, characterized in that, The monitor is equipped with crosshairs to indicate the center of the weld in the second image.

8. The laser welding apparatus for split-image focusing according to claim 1, characterized in that, It also includes a control system for controlling the movement of the laser welding head.

9. The laser welding apparatus for split-image focusing according to claim 1, characterized in that, The laser welding head has a lens with a magnesium fluoride coating at its emission port.

10. A laser welding method, characterized in that, The laser welding apparatus for split-image focusing according to any one of claims 1-9 includes the following steps: The focus is determined by manually observing the first image. The method is as follows: if the welds on both sides of the first image are aligned, it indicates that the focus has been achieved; otherwise, it indicates that the focus has not been achieved. If the result indicates that the focus has not been achieved, adjust the distance between the laser welding head and the workpiece until the focus is achieved; The workpiece is welded using a laser welding head. The positional relationship between the weld seam and the laser focus on the workpiece is monitored in real time by manually observing a second image, so as to adjust the position of the laser welding head.

Images