Spot center repositioning mechanism, system, and apparatus for laser welding equipment

Abstract

The application discloses a spot center repositioning mechanism, system and device for a laser welding device, and belongs to the technical field of laser welding.The application sets a calibration plate on a welding plane, sets a calibration hole at the center position of the calibration plate, finds the center position coordinates and shape area size of the offset spot by using the principle that a photoelectric detector outputs an electric signal under light irradiation, omits the step of manually debugging the mechanical structure by a process personnel, automatically finds the actual position and size of the current spot, modifies corresponding software welding parameters, and adaptively performs welding operation; the degree of intelligence is high, the degree of dependence on the process personnel is low, the positioning speed is fast, the debugging time before welding is greatly saved, and the welding efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of laser welding technology, and more specifically, relates to a spot center repositioning mechanism, system and device for laser welding equipment. Background Technology

[0002] In the initial assembly and debugging phase of laser welding equipment, the laser spot is adjusted to align its center with the center of the processing plane. However, after a period of production, minor changes in the mechanical structure, such as machine downtime for parts replacement or loosening of components, may cause the laser head center to shift relative to the welding plane center, resulting in a shift in the center of the laser spot illuminating the plane. The relative vertical distance between the two may also change, altering the spot size. If welding is performed directly without adjustment, it will lead to incorrect welding and affect the welding yield.

[0003] Currently, the common approach is for process engineers to manually adjust the positions of each screw and component multiple times to bring the center of the laser spot back to the center of the welding plane and to restore the size of the laser spot to its original size.

[0004] However, this manual adjustment method is quite cumbersome, time-consuming, has a low level of intelligence, and requires a high level of technical expertise from process personnel, which greatly affects operational efficiency. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a spot center repositioning mechanism, system and equipment for laser welding equipment, which aims to solve the problem of low operation efficiency of manual adjustment.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a spot center repositioning mechanism for a laser welding equipment, comprising:

[0007] A calibration plate with calibration holes;

[0008] The photoelectric detection unit located on the bottom of the calibration plate has its photosensitive surface directly below the calibration hole, with no light-transmitting gap between them. It is used to convert the received light signal into an electrical signal when the light spot passes through the calibration hole and feed it back to the central processing unit to determine the current center position of the light spot.

[0009] Preferably, the calibration hole has the same shape as the minimum spot of the laser welding equipment, and its size does not exceed the size of the minimum spot.

[0010] To achieve the above objectives, in a second aspect, the present invention provides a spot center repositioning system for laser welding equipment, comprising:

[0011] The spot center repositioning mechanism as described in the first aspect;

[0012] The imaging unit is fixedly connected to the laser head, and its field of view center coincides with the center of the light spot, which is used to feed back the image information under the field of view to the central processing unit.

[0013] The central processing unit is used to control the laser head to emit a laser beam. Based on the image information fed back by the imaging unit, it controls the laser head to move traversing in the X and Y directions, and records the coordinates and time points of each point of the laser head during the traversal movement in real time. By comparing the time of the electrical signal fed back by the photoelectric detection unit, the current center position of the light spot is determined.

[0014] Preferably, when the size of the calibration aperture is the same as the size of the smallest light spot, the central processing determines the current center position of the light spot in the following way:

[0015] Find the coordinates of the calibration hole in a coordinate system with the center of the light spot as the origin;

[0016] Perform a Cartesian coordinate system transformation to calculate the center position of the light spot in the coordinate system with the calibration hole as the origin.

[0017] Preferably, when the calibration aperture size is smaller than the minimum spot size, the central processing determines the current spot center position in the following manner:

[0018] Based on the start and stop times of the electrical signals output by the photoelectric detection unit during each time period during the traversal movement, and using the coordinate information of the points traversed by the laser head during that time period, the size of the light spot area and the center position are calculated geometrically.

[0019] Preferably, the traversal range of the laser head is twice the design range of the laser head's offset.

[0020] Preferably, the traversal path is a cross, an arc rotation, or a square.

[0021] To achieve the above objectives, in a third aspect, the present invention provides a laser welding device that integrates a spot center repositioning system as described in the second aspect;

[0022] During operation, remove the workpiece to be welded, place the calibration plate on the limiting fixture, and ensure that the calibration plate and the upper surface of the workpiece to be welded are on the same welding plane; automatically find the current spot center position and spot size; remove the calibration plate and replace it with the workpiece to be welded; move the weld point of the workpiece to be welded to the repositioned spot center position, so that the weld point coincides with the spot center, and then perform laser welding.

[0023] Preferably, the central processing unit is also used to combine the solder joint area of ​​the workpiece to be soldered and the size of each light spot to calculate and match which light spots correspond to which optical path units to be lit for soldering.

[0024] Preferably, the central processing unit is also used to store the illuminated optical path units as process recipes, and when welding solder joints of the same size again, the process recipe is directly retrieved for welding.

[0025] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0026] This invention provides a laser spot center repositioning mechanism, system, and device for laser welding equipment. By setting a calibration plate on the welding plane and a calibration hole at the center of the calibration plate, the center coordinates and shape / area of ​​the offset laser spot are located using the principle of a photodetector outputting an electrical signal upon illumination. This eliminates the need for manual adjustment of the mechanical structure by process personnel, automatically finding the actual position and size of the current laser spot, modifying the corresponding software welding parameters, and adaptively performing the welding operation. It features a high degree of intelligence, low dependence on process personnel, fast positioning speed, significantly reducing pre-welding setup time, and improving welding efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a spot center repositioning system for laser welding equipment provided in an embodiment of the present invention.

[0028] Figure 2 These are schematic diagrams of the normal, unoffset position of the light spot provided in the embodiments of the present invention. (a) is a schematic diagram of the normal, unoffset position, and (b) is a top view of the normal, unoffset position.

[0029] Figure 3 These are schematic diagrams of the spot offset provided in the embodiments of the present invention. (a) is a schematic diagram of the offset position, and (b) is a top view of the offset.

[0030] Figure 4 This is a schematic diagram of the spot traversal path and coordinate transformation provided in the embodiment of the present invention. (a) is a schematic diagram of the traversal path, (b) is a positional relationship diagram under the camera field of view coordinate system, and (c) is a positional relationship diagram under the calibration hole coordinate system.

[0031] Figure 5 The following is a schematic diagram of the light spot shape drawn by traversing and lighting multiple times according to the embodiments of the present invention: (a) is a schematic diagram of the light spot moving and continuously lighting the photodetector; (b) is a positional relationship diagram under the camera field of view coordinate system; and (c) is a positional relationship diagram under the calibration hole coordinate system.

[0032] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0033] 1-Calibration steel plate; 2-Calibration hole; 3-Photodetector; 4-Laser head; 5-CCD camera; 6-Sliding assembly; 7-Central processing unit; 8-Working platform; 9-Limit fixture; 10-Base; 11-Laser beam. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] The concept of this invention is as follows: First, find the center position and size of the light spot on the current processing plane, and then move the welding point of the workpiece to be welded to the center of the light spot for welding. That is, the current light spot is used directly for processing, and the welding point of the workpiece is moved. There is no need to adjust the center of the light spot back to its original position or the size back to its original size, thus saving the manual adjustment step.

[0036] This invention provides a spot center repositioning mechanism for laser welding equipment, comprising:

[0037] A calibration plate with calibration holes;

[0038] The photoelectric detection unit located on the bottom of the calibration plate has its photosensitive surface directly below the calibration hole, with no light-transmitting gap between them. It is used to convert the received light signal into an electrical signal when the light spot passes through the calibration hole and feed it back to the central processing unit to determine the current center position of the light spot.

[0039] Preferably, the calibration hole has the same shape as the minimum spot of the laser welding equipment, and its size does not exceed the size of the minimum spot.

[0040] This invention provides a spot center repositioning system for laser welding equipment, comprising:

[0041] Such as the above-mentioned spot center repositioning mechanism;

[0042] The imaging unit is fixedly connected to the laser head, and its field of view center coincides with the center of the light spot, which is used to feed back the image information under the field of view to the central processing unit.

[0043] The central processing unit is used to control the laser head to emit a laser beam. Based on the image information fed back by the imaging unit, it controls the laser head to move traversing in the X and Y directions, and records the coordinates and time points of each point of the laser head during the traversal movement in real time. By comparing the time of the electrical signal fed back by the photoelectric detection unit, the current center position of the light spot is determined.

[0044] Preferably, when the size of the calibration aperture is the same as the size of the smallest light spot, the central processing determines the current center position of the light spot in the following way:

[0045] Find the coordinates of the calibration hole in a coordinate system with the center of the light spot as the origin;

[0046] Perform a Cartesian coordinate system transformation to calculate the center position of the light spot in the coordinate system with the calibration hole as the origin.

[0047] Preferably, when the calibration aperture size is smaller than the minimum spot size, the central processing determines the current spot center position in the following manner:

[0048] Based on the start and stop times of the electrical signals output by the photoelectric detection unit during each time period during the traversal movement, and using the coordinate information of the points traversed by the laser head during that time period, the size of the light spot area and the center position are calculated geometrically.

[0049] Preferably, the traversal range of the laser head is twice the design range of the laser head's offset.

[0050] Preferably, the traversal path is a cross, an arc rotation, or a square.

[0051] This invention provides a laser welding device that integrates a spot center repositioning system as described above;

[0052] During operation, remove the workpiece to be welded, place the calibration plate on the limiting fixture, and ensure that the calibration plate and the upper surface of the workpiece to be welded are on the same welding plane; automatically find the current spot center position and spot size; remove the calibration plate and replace it with the workpiece to be welded; move the weld point of the workpiece to be welded to the repositioned spot center position, so that the weld point coincides with the spot center, and then perform laser welding.

[0053] Preferably, the central processing unit is also used to combine the solder joint area of ​​the workpiece to be soldered and the size of each light spot to calculate and match which light spots correspond to which optical path units to be lit for soldering.

[0054] Preferably, the central processing unit is also used to store the illuminated optical path units as process recipes, and when welding solder joints of the same size again, the process recipe is directly retrieved for welding.

[0055] Example

[0056] In this embodiment, the laser welding equipment is a laser welding machine. The optical path structure includes multiple optical path units, which can project multiple light spots of different sizes and shapes onto the welding plane, with the centers of each spot not overlapping. By illuminating at least one light spot, welding light spots of different sizes and shapes can be combined. Before welding, during self-test initialization, each light spot is illuminated sequentially, and the center coordinates and shape / size of each spot are determined. The central processing unit, considering the shape and area of ​​the weld joint on the workpiece, calculates which light spots to illuminate. Multiple light spots combined to form a large light spot can be projected onto the welding plane for processing.

[0057] like Figure 1 As shown, this embodiment provides a spot center repositioning system for laser welding equipment, comprising:

[0058] A calibration steel plate 1 has a circular calibration hole 2 at its center;

[0059] The photodetector 3 located on the bottom surface of the calibration plate has its photosensitive surface directly below the calibration hole, and there is no light-transmitting gap between them. It is used to convert the received light signal into an electrical signal when the light spot passes through the calibration hole and feed it back to the central processing unit to determine the current center position of the light spot.

[0060] CCD camera 5 is fixedly connected to laser head 4. Its field of view center coincides with the center of the light spot, and its shooting direction is the same as the laser beam irradiation direction. It is used to feed back the image information under the field of view to central processing unit 7.

[0061] The central processing unit 7 is used to control the laser head 4 to emit a laser beam 11. Based on the image information fed back by the imaging unit, it controls the sliding component 6 to drive the laser head 4 to move traversely in the X and Y directions, and records the coordinates and time points of each point of the laser head during the traversal movement in real time. By comparing the time of the electrical signal fed back by the photoelectric detection unit, the current center position of the light spot is determined.

[0062] The CCD camera is fixedly mounted on the laser head and can be connected via threads or screws; there are no restrictions on this connection. Regarding their position: the CCD camera can be coaxial with the laser beam or off-axis, as long as the center of the CCD camera's field of view coincides with the center of the laser spot.

[0063] A limiting fixture 9 is installed on the working platform 8. During spot repositioning, the calibration steel plate 1 is placed on the limiting fixture 9. The calibration steel plate and the upper surface of the workpiece to be welded must be on the same welding plane, i.e., the processing plane on which the spot is projected, and the center of the calibration steel plate (i.e., the calibration hole) is located at the center of the working platform. The photodetector can be attached to the bottom of the calibration steel plate in a manner similar to adhesive. Through the setting of the limiting fixture, space can be reserved between the calibration steel plate and the working platform to accommodate the photodetector. When the laser beam irradiates the calibration hole, the photodetector receives the light signal, converts it into an electrical signal, and outputs it to the central processing unit; when the laser beam does not irradiate the calibration hole, the photodetector has no signal output. The spot center repositioning system calculates the position of the spot after offset by finding the coordinate position of the calibration hole. After the spot repositioning is completed, the calibration steel plate is removed and replaced with the workpiece to be welded. All components are located on the base 10.

[0064] like Figure 2 As shown, under normal circumstances, the center of the CCD camera's field of view and the center of the laser spot illuminating the calibration steel plate both coincide with the calibration hole, and the calibration hole and the center of the laser spot are both located at the origin of the CCD camera's field of view coordinate system.

[0065] like Figure 3 As shown, when parts are replaced or mechanical structures are altered due to loosening of parts, the center of the CCD camera's field of view and the center of the light spot shift, which is equivalent to the position of the calibration hole shifting in the CCD camera's field of view coordinate system.

[0066] The working process of the light spot center repositioning system is as follows:

[0067] The system is started, and the CCD camera captures images of a designated area in a coordinate system with the current light spot center as the origin, and then sends the images back to the central processing unit.

[0068] The central processing unit controls the drive motor to drive the laser head to traverse and move within the designated area. The traversal and movement method is as follows: Figure 4 As shown, when the light spot passes through the calibration hole, the photodetector is illuminated and outputs an electrical signal that is fed back to the central processing unit.

[0069] When the spot diameter is comparable to the aperture size of the calibration aperture, the central processing unit records the coordinates of each point traversed and its corresponding time point as the laser head moves. Based on the time t1 of the photodetector's output electrical signal, the coordinates of the point the laser head has moved to at that moment are found; these are the coordinates of the calibration aperture. The coordinates O(a,b) of the calibration aperture in the CCD camera's field of view coordinate system are then transformed into a Cartesian coordinate system to calculate the coordinates O'(X,Y) of the offset spot in a coordinate system with the calibration aperture as the origin, where the x-coordinate X = -a and the y-coordinate Y = -b.

[0070] like Figure 5As shown, when the spot diameter is larger than the calibration aperture, the photodetector will be illuminated multiple times during the traversal process, outputting electrical signals for multiple time periods. The movement of the spot during one of these time periods, t, is illustrated. m As the edge of the light spot passes the calibration aperture and continues to move, the photodetector remains illuminated and outputs a signal until t. n The other opposite edge of the time-lapse light spot moves away from the calibration aperture. The central processing unit outputs the electrical signal at the time point t within each time period. m and the time point t when output stops n Find the coordinates of the points the laser head passes through at these moments, draw an image to represent the shape of the light spot, and then calculate the size of the light spot area and the coordinates of its center position.

[0071] For example, the light spot is a square, and the coordinates of points on the square are known. Take the point with the largest x-coordinate A(p,q) and the point with the smallest y-coordinate B(e,f), and calculate the side length of the square. According to the formula for calculating the area of ​​a square, the area of ​​the light spot can be calculated as S = L. 2 =(pe) 2 +(fq) 2 Take the point C(h,i) with the smallest x-coordinate and the point D(j,k) with the largest y-coordinate. Calculate the x-coordinate a = h + (ph) / 2 and the y-coordinate b = f + (kf) / 2 of the center position of the light spot (i.e., the calibration hole). Then perform a Cartesian coordinate transformation to offset the center position coordinates O'(X,Y) of the light spot in the coordinate system with the calibration hole as the origin, where X = -(h + (ph) / 2) and Y = -(f + (kf) / 2).

[0072] The size of the designated area that the laser head traverses is twice the design range of the laser head's offset. For example, if the laser head's offset range is designed to be (5mm × 5mm), the designated area that the laser head traverses is (10mm × 10mm). The traversal path is not limited to... Figure 4 The path shown can also be a cross, an arc, or a rotating path.

[0073] After determining the center position and size of the light spot using the above method, the central processing unit automatically modifies the corresponding software welding parameters, thereby controlling the movement of the motion platform to move the welding point of the workpiece to the center position of the light spot for welding.

[0074] In some embodiments, the central processing unit displays the center position and size information of the laser spot on the display screen, and the process engineer modifies the corresponding software welding parameters accordingly.

[0075] This invention automatically locates the center position and size of the currently offset laser spot during the equipment's self-test initialization program and modifies the corresponding software welding parameters. This allows the equipment to adaptively perform welding operations based on the actual position and size of the current laser spot.

[0076] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A spot center repositioning mechanism for laser welding equipment, characterized in that, include: A calibration plate with calibration holes; The photoelectric detection unit located on the bottom of the calibration plate has its photosensitive surface directly below the calibration hole, with no light-transmitting gap between them. It is used to convert the received light signal into an electrical signal when the light spot passes through the calibration hole and feed it back to the central processing unit to determine the current center position of the light spot. When the size of the calibration aperture is the same as the size of the minimum spot, the central processing determines the current spot center position in the following way: find the coordinates of the calibration aperture in a coordinate system with the spot center position as the origin; perform a Cartesian coordinate system transformation to calculate the spot center position in a coordinate system with the calibration aperture as the origin; when the size of the calibration aperture is smaller than the size of the minimum spot, the central processing determines the current spot center position in the following way: based on the start and stop times of the electrical signals output by the photoelectric detection unit during each time period during the traversal movement, and based on the coordinate information of the points passed by the laser head during that time period, calculate the spot area and center position geometrically.

2. The mechanism as described in claim 1, characterized in that, The calibration hole has the same shape as the minimum spot of the laser welding equipment, and its size does not exceed the size of the minimum spot.

3. A spot center repositioning system for laser welding equipment, characterized in that, include: The spot center repositioning mechanism as described in claim 1 or 2; The imaging unit is fixedly connected to the laser head, and its field of view center coincides with the center of the light spot, which is used to feed back the image information under the field of view to the central processing unit. The central processing unit is used to control the laser head to emit a laser beam. Based on the image information fed back by the imaging unit, it controls the laser head to move traversing in the X and Y directions, and records the coordinates and time points of each point of the laser head during the traversal movement in real time. By comparing the time of the electrical signal fed back by the photoelectric detection unit, the current center position of the light spot is determined.

4. The system as described in claim 3, characterized in that, The traversal range of the laser head is twice the designed offset range of the laser head.

5. The system as described in claim 4, characterized in that, The traversal path is a cross, an arc rotation, or a square.

6. A laser welding device, characterized in that, It is integrated with a spot center repositioning system as described in any one of claims 3 to 5; During operation, remove the workpiece to be welded, place the calibration plate on the limiting fixture, and ensure that the calibration plate and the upper surface of the workpiece to be welded are on the same welding plane; automatically find the current spot center position and spot size; remove the calibration plate and replace it with the workpiece to be welded; move the weld point of the workpiece to be welded to the repositioned spot center position, so that the weld point coincides with the spot center, and then perform laser welding.

7. The device as described in claim 6, characterized in that, The central processing unit is also used to combine the solder joint area of ​​the workpiece to be soldered and the size of each light spot to calculate and match which light spots correspond to which optical path units to be lit for soldering.

8. The device as described in claim 7, characterized in that, The central processing unit is also used to store the illuminated optical path units as process recipes, and when welding solder joints of the same size again, the process recipe is directly retrieved for welding.

Images