Visual positioning large-area laser milling combined machining device and machining method

Abstract

The invention discloses a visual positioning large-area laser milling combined machining device and method, and belongs to the field of machining. The device comprises a laser unit and a milling unit, the laser unit comprises a laser, a light path, a camera, a protective cover and a fixing frame, and the milling unit comprises a machine tool spindle and a mechanical platform. The invention further provides a laser milling combined machining method based on visual positioning, the machining pattern and the feeding path are changed according to the workpiece installation angle, the laser machining pattern is divided into sub-patterns, the sub-patterns are machined, the characteristics of a molten pool at the splicing position are extracted, follow-up machining parameters are optimized, and the machining pattern at the splicing position is compensated to reduce the machining molten pool. And then milling machining is carried out on the machining surface. The mechanical platform is used for driving the laser galvanometer, linkage control is matched with a laser milling machine, composite milling machining is achieved while precise large-area pattern laser splicing machining is achieved, it is guaranteed that the high-precision conformity of a laser pattern and a milling path is achieved, and the large-area machining quality of a microstructure is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of laser milling composite processing, and in particular to a large-area laser milling composite processing device and a processing method for visual positioning. Background Art

[0002] In recent years, laser processing and micro-milling have been increasingly used in aerospace, defense industry, medical biology, and electronic communications. Laser processing is an excellent micro-structure processing method due to its high processing quality, small heat-affected zone, and high processing efficiency; similarly, micro-milling, as a form of cold processing, can effectively avoid changes in the physical and chemical properties of materials under cutting lubrication conditions, and process microstructures under conditions with minimal impact on the substrate.

[0003] However, when processing microstructures over a large area, multiple processes are often required, which places extremely high demands on its positioning accuracy. The current manual positioning method for processing microstructures is relatively random, and it is difficult to place the workpiece directly in the appropriate position when placing it, and it cannot meet the position and angle requirements of the workpiece. It requires manual repeated adjustments, with low positioning accuracy and a long time consumption, which seriously reduces the processing efficiency and processing accuracy. In addition, the processing range of the laser galvanometer is limited (not exceeding 100mm*100mm), and its large-area processing requires the coordinated movement of the mechanical platform. However, the laser galvanometer and the mechanical platform are currently separate control systems, and the linkage control of the two cannot be achieved. If manual positioning is used, the processing quality is low and the processing efficiency is poor. At the same time, the splicing patterns before and after laser splicing are affected by multiple factors such as the laser switch, the galvanometer deflection, and the start and stop of the motion platform, which can easily cause the splicing molten pool to be too deep or the laser pattern to be not spliced ​​in place, resulting in poor processing quality at the splicing point, which seriously limits the large-area microstructure laser processing.

[0004] Therefore, visual recognition of the position and angle of microstructure workpieces and the equipment and control of the laser galvanometer mechanical platform are the key to achieving large-scale preparation of microstructures. They can effectively expand the processing area, improve processing accuracy and efficiency, and are of great significance for achieving continuous and precise processing of large-area microstructures. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a large-area laser milling composite processing device and method with visual positioning.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A large-area laser milling composite processing device with visual positioning includes a laser unit and a milling unit. The laser unit includes a laser, an optical path and a camera. The laser generates and emits laser light into the optical path. The optical path changes the laser transmission path and processes the laser light, and finally irradiates vertically downward to the surface of a workpiece. The camera observes the position of the laser processing area and extracts the workpiece position information. The milling unit includes a machine tool spindle and a mechanical platform. The mechanical platform can move in the X, Y, and Z axis directions relative to the machine tool spindle. The laser unit is fixed on the machine tool spindle and moves together with the machine tool spindle. The workpiece is placed on the mechanical platform.

[0008] To optimize the above technical solutions, the specific measures taken also include:

[0009] The above-mentioned mechanical platform includes a base, a Y-axis drive, a machine tool platform, a heightening platform and an arch frame. The base is placed on the ground, the Y-axis drive is fixed in the center of the base, the machine tool platform is slidably set on the Y-axis drive, and the Y-axis drive can drive the machine tool platform to move in the Y-axis direction. The heightening platform is fixed on one side of the machine tool platform to adjust the workpiece processing height, and the arch frame is fixed in the middle and upper part of the base to support the machine tool spindle and the laser unit thereon.

[0010] The above-mentioned machine tool spindle includes a tool, a tool holder, a Z-axis drive, a nozzle, a spindle, an X-axis drive and a spindle housing. The tool is clamped in the tool holder, the tool holder is clamped at the bottom of the spindle, the nozzle is fixed on the lower side of the spindle, the nozzle is used to spray cutting fluid, the spindle is fixed to the X-axis drive through the Z-axis drive, the X-axis drive is fixed to the arch frame, the X-axis drive is used to drive the Z-axis drive to move in the X-axis direction, the Z-axis drive is used to drive the spindle to move in the Z-axis direction, and the spindle housing covers the outside of the spindle to protect the spindle.

[0011] The above-mentioned laser includes a laser generator, a transmission optical fiber and a laser emission head. The laser generator is fixed on the main shaft of the machine tool. The laser generator can emit a laser beam. The transmission optical fiber connects the laser generator and the laser emission head. The transmission optical fiber can transmit the laser beam. The laser emission head is directly opposite to the laser optical path.

[0012] The above optical path includes a first reflector, a galvanometer and a second reflector. The first reflector refracts the laser beam emitted from the laser emission head into the galvanometer, and the second reflector is used to refract the laser beam emitted from the galvanometer to the surface of the workpiece.

[0013] The above-mentioned laser unit also includes a protective cover and a fixing frame, the optical path is fixed on the fixing frame, the fixing frame is fixedly installed on the base, the protective cover is wrapped around the outside of the laser and the optical path to prevent liquid and dust from contacting the laser and the optical path, the camera is a high-magnification coaxial CCD, the camera is fixed on the camera fixing frame, and the camera fixing frame is fixed on the second fixing frame.

[0014] The protective cover is provided with a ring light and infrared glass. The ring light is used to illuminate the laser processing area and provide a clear field of view for the camera.

[0015] A large-area laser milling composite processing device with visual positioning also includes a control unit, which includes a laser control unit, a machine tool control unit and a computer. The laser control unit is used to control the operation of the laser, the optical path and the camera, and the machine tool control unit is used to control the movement and milling of the milling unit. Both the laser control unit and the machine tool control unit are connected to the computer, and the computer is used to receive information from the laser control unit and the machine tool control unit and send instructions to the laser control unit and the machine tool control unit.

[0016] A large-area laser milling composite processing method with visual positioning, using the large-area laser milling composite processing device, the processing method specifically includes the following steps:

[0017] Step 1: Fix the workpiece on the mechanical platform and draw the laser processing graphics and milling processing path on the computer;

[0018] Step 2: Drive the mechanical platform and the machine tool spindle to move the corner of the workpiece into the range of the camera lens;

[0019] Step 3: The camera identifies the vertices and two sides of the workpiece corners within the lens range, obtains the X, Y difference between the camera center coordinates and the workpiece corner vertex position coordinates in the current field of view, reads the current coordinates of the machine tool based on the X, Y position relationship fixed between the machine tool spindle center and the camera center, converts the workpiece vertex coordinates in the field of view by two X, Y relative relationships to obtain the workpiece vertex coordinates in the absolute coordinate system of the machine tool, and establishes the workpiece coordinate system in the machine tool with the workpiece corner vertex as the origin;

[0020] Step 4: By identifying the installation angle of the workpiece, the computer automatically transforms the drawn laser processing graphics and milling processing tool path, and rotates the laser processing graphics and milling processing tool path by the identified angle according to the installation direction to form the transformed laser processing graphics and tool path;

[0021] Step 5: The computer divides the transformed laser processing graphics into grids according to the set size to obtain several rows and columns of sub-graphics, and generates the corresponding machine tool movement path according to the division size and the workpiece coordinate system position;

[0022] Step 6: The laser unit first moves to the top of the first segmented sub-area, and the camera retains the unprocessed surface morphology image of this area. At this time, the laser processable area has completely covered this sub-area, and the laser processing of the graphics in this sub-area is carried out;

[0023] After the processing of this sub-region is completed, the camera identifies the surface morphology of the processed sub-region, compares it with the unprocessed surface morphology image, identifies the actual processed graphics, and extracts the processed graphics at the edge segmentation of the sub-region;

[0024] Step 7: The laser unit moves to the next sub-area for processing again, identifies the images before and after processing, and extracts the actual processing graphics after both sub-areas have been processed;

[0025] Step 8: Compare the appearance of the front sub-area and the rear sub-area at the segmentation point, determine the overall pattern deviation of the actual laser processing, generate the processing compensation parameter m for the galvanometer processing height and the galvanometer sub-area positioning, and automatically adjust the machine tool and galvanometer movement parameters according to the compensation parameter m when processing the next sub-area;

[0026] At the same time, the size of the laser processing molten pool at the joint of the two sub-areas is judged, and the compensation parameter n is generated to compensate the line length at the edge connection of each sub-area, reduce the influence of the laser processing molten pool overlap on the processing quality of the joint, and automatically adjust the processing parameters according to the compensation parameter n and process the next sub-area when processing;

[0027] Step 9: Repeat steps 7 and 8, continuously identify and compensate the processed graphics, until all segmented areas are processed, and complete the splicing processing of large-area graphics that exceeds the processing range of a single laser galvanometer;

[0028] Step 10: The computer sends the tool path with the changed angle to the machine tool control system, and further performs milling on the surface of the workpiece after laser processing to achieve high-precision matching between the laser processing graphics and the milling processing path.

[0029] In step eight, the appearance of the front sub-region and the rear sub-region at the segmentation is compared to determine the overall pattern deviation of the actual laser processing, and the specific method for generating the processing compensation parameter m for the galvanometer processing height and the galvanometer sub-region positioning is:

[0030] Compare the front and back sub-area images to obtain the actual processed graphics, dynamically identify the line width of the actual processed graphics, generate the center line of the processed graphics, and use the line width to determine the edge endpoint position of the center line at the splicing point;

[0031] According to the theoretical processing graph, the theoretical processing starting endpoints of the rear sub-region after the calculation of the molten pool compensation at the end point of the front sub-region dividing line are assumed to be the a sequence a1, a2, a3..., and the starting endpoints after the actual molten pool compensation are marked as the b sequence b1, b2, b3...;

[0032] First, compensate for the Y-direction error of the galvanometer sub-region positioning. By comparing the theoretical processing pattern with the b-sequence endpoints, locate the actual segmentation edge of this sub-region, compare the Y-direction deviation of the midpoint of the segmentation edge of the front and rear sub-regions, compensate for the Y-axis positioning of the galvanometer in the sub-region, and generate a sub-region compensation model after the Y-direction compensation of the galvanometer positioning. The compensated b-sequence is recorded as b'sequence.

[0033] Secondly, the rotation error of the sub-region positioning of the galvanometer mirror is compensated. The angle error between the b' sequence dividing line and the a sequence dividing line is identified through the X-direction coordinate difference of the corresponding endpoints of the a and b' sequences, and the error identified by the segmentation edge line is converted to the rotation angle compensation of the sub-region galvanometer positioning center, and the corresponding Y-axis compensation caused by the angle compensation is generated by multiplying the sine value of the identified rotation angle by half of the length of the segmented area, and the Y-axis compensation is also added to the Y-axis compensation of the galvanometer positioning;

[0034] Finally, compensate for the galvanometer processing height error by using the Y-direction coordinate difference of the corresponding endpoints of the a and b' sequences. If the value is smallest near the center of the dividing line and the values ​​on both sides of the dividing line are increasing, it means that there is a deviation in the galvanometer processing height. If the Y difference of the first pair of endpoints is greater than zero and the Y difference of the last pair of endpoints is less than zero, then the compensation is to reduce the galvanometer processing height. If the Y difference of the first pair of endpoints is less than zero and the Y difference of the last pair of endpoints is greater than zero, then the compensation is to increase the galvanometer processing height.

[0035] Multiple processing, multiple compensation, and continuous iteration of compensation parameter m make most of the laser processing trajectory endpoints connected;

[0036] In step eight, the size of the laser processing molten pool at the joint of the two sub-areas is judged, and the specific method for generating the compensation parameter n is as follows:

[0037] Compare the front and back sub-area images to obtain the actual processing graphics, dynamically identify the line width of the actual processing graphics, generate the center line of the processing graphics, and use the line width to determine the edge endpoint position of the center line splicing;

[0038] Assume that the average line width of actual processing is 2r, the bending angle of the line segment to be connected on both sides of the dividing line is α, the remaining unprocessed area when the rear line segment is normally compensated is φ1, and the remaining unprocessed area when the line segment is tangent to the front line segment is φ2. According to the recognized connection angle, the inward compensation distance of the line segment is different.

[0039] When α≥90°, keep processing the line segments of the old sub-region to the end point of the dividing line, and shorten the line segments of the new sub-region to the region by a distance n1=r~2r, so that the connection is overlapped slightly without expanding the molten pool, and reduce the unprocessed area between the two line segment end points and the molten pool, so that φ1≤75%φ2, and obtain the most continuous connection edge;

[0040] When α<90°, keep processing part of the line segments in the old sub-area to the end point of the dividing line, and shorten the line segments in the new sub-area inward by a distance n2, 5r>n2>2r, φ1≤75%φ2;

[0041] When the front and rear sub-areas are spliced, multiple line segments are spliced. For multiple groups of line segments with α≥90°, n1 is used to compensate, and for multiple groups of line segments with α<90°, n2 is used to compensate.

[0042] The beneficial effects of the present invention are as follows: the present invention effectively expands the laser processing area and reduces the workpiece repositioning error by combining the laser unit with the milling unit through the motion platform; visual recognition is adapted to the laser processing of a variety of different materials; continuous proofreading and multiple compensations improve the overall accuracy of the splicing processing sub-patterns and large-area patterns, while reducing the size of the molten pool at the connection and improving the quality of the splicing edge lines; and improving the processing accuracy and efficiency of continuous and precise processing of large-area microstructures. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the overall structure of the large-area laser milling composite processing device with visual positioning of the present invention.

[0044] Figure 2 This is a schematic diagram of the laser unit structure of the large-area laser milling composite processing device with visual positioning of the present invention.

[0045] Figure 3 It is a schematic diagram of a control unit of the large-area laser milling composite processing device with visual positioning of the present invention.

[0046] Figure 4 A schematic diagram of the transmission optical fiber channel of the large-area laser milling composite processing device with visual positioning of the present invention.

[0047] Figure 5 The present invention is a flow chart of the large-area laser milling composite processing method with visual positioning.

[0048] Figure 6 It is a processing and machining schematic diagram of the large-area laser milling composite machining method with visual positioning of the present invention.

[0049] Figure 7 This is a flow chart of the compensation method of the large-area laser milling composite processing method with visual positioning of the present invention.

[0050] Figure 8 It is a schematic diagram of the molten pool compensation method of the large-area laser milling composite processing method with visual positioning of the present invention.

[0051] Description of reference numerals: 1. laser unit; 2. milling unit; 3. control unit; 11. mechanical platform; 12. machine tool spindle; 111. base; 112. Y-direction drive; 113. machine tool platform; 114. heightening platform; 115. arch frame; 121. tool; 122. tool handle; 123. Z-direction drive; 124. nozzle; 125. spindle; 126. X-direction drive; 127. spindle housing; 21. laser; 22. optical path; 23. camera; 2 4. Protective cover; 25. Fixing frame; 211. Laser generator; 212. Transmitting optical fiber; 213. Laser transmitting head; 221. First reflecting mirror; 222. Vibrating mirror; 223. Second reflecting mirror; 231. Camera fixing frame; 232. High-magnification coaxial CCD; 241. Transmitting head cover; 242. Transparent film; 243. Acrylic shell; 244. Ring light; 245. Infrared glass; 31. Laser control unit; 32. Machine tool control unit; 33. Computer. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0053] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0054] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0055] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0056] like Figure 1-4 As shown, the present invention provides a large-area laser milling composite processing device with visual positioning, comprising:

[0057] Laser unit 2 and milling unit 1.

[0058] The laser unit 2 includes a laser 21, an optical path 22, a camera 23, a protective cover 24 and a fixing frame 25. The laser 21 generates and emits laser light into the optical path 22. The optical path 22 changes the laser transmission path and processes the laser light, and finally irradiates the surface to be processed vertically downward. The optical path 22 is fixed in the fixing frame 25. The camera 23 observes the position of the laser processing area and extracts the workpiece position information. The protective cover 24 provides light and wraps the exposed part of the laser unit to prevent liquid and dust from damaging the laser unit 2.

[0059] The milling unit 1 includes a machine tool spindle 12 and a mechanical platform 11. The machine tool spindle 12 can move in the X-axis direction and the Z-axis direction, and the mechanical platform 11 can move in the Y-axis direction. The laser unit 2 is fixed on the machine tool spindle 12 and moves together with the machine tool spindle 12.

[0060] The mechanical platform 11 includes a base 111, a Y-axis drive 112, a machine platform 113, a heightening platform 114 and an arch frame 115. The base 111 is placed on the ground, the Y-axis drive 112 is fixed in the center of the base 111, the machine platform 113 is the target platform for the Y-axis drive 112 to move and control, the heightening platform 114 is fixed on one side of the machine platform 113 to adjust the workpiece processing height, and the arch frame 115 is fixed in the upper middle part of the base 111 to support the machine spindle 12 and the laser unit 2 thereon, and provide the X-direction movement space of the machine spindle 12. When the Y-axis drive 112 moves, the machine platform 113 and the heightening platform 114 move to the set position in the Y direction according to the moving distance.

[0061] The machine tool spindle 12 includes a tool 121, a tool handle 122, a Z-direction driver 123, a nozzle 124, a spindle 125, an X-direction driver 126 and a spindle housing 127. The tool 121 is clamped in the tool handle 122, the tool handle 122 is clamped at the lower part of the spindle 125, the lower left side of the spindle 125 is close to the fixed nozzle 124 for spraying cutting fluid, the spindle 125 is fixed to the X-direction driver 126 through the Z-direction driver 123, the X-axis is fixed to the arch frame 115, the spindle housing 127 is fixed to the X-direction driver 126, and moves together with the spindle 125 in the X direction. When the spindle 125 is raised or lowered, the spindle housing 127 does not move up and down with the spindle 125, and only serves to shield the upper part.

[0062] The laser 21 includes a laser generator 211, a transmission optical fiber 212, and a laser emission head 213. The laser generator 211 is fixed to the fixed part on the top rear side of the machine tool spindle 12. The laser generator 211 can emit a laser beam. The transmission optical fiber 212 connects the laser generator 211 and the laser emission head 213. The transmission optical fiber 212 can transmit the laser beam. The laser emission head 213 is fixed in front of the machine tool spindle 12, facing the laser optical path 22.

[0063] The optical path 22 includes a first reflector 221, a galvanometer 222, and a second reflector 223. The first reflector 221 is fixed to the right side of the laser emission head 213. The optical path is turned downward by 90° so that the optical path is vertically transmitted downward into the galvanometer 222. The galvanometer 222 is fixed to the outside of the second fixed frame 25 and the light outlet is facing the positive direction of the Y axis. The optical path is turned inward by 90°. The second reflector 223 is fixed to the inside of the second fixed frame 25 and aligned with the light outlet of the galvanometer 222. The optical path is rotated downward by 90° and irradiated to the surface to be processed.

[0064] The camera 23 is a high-magnification coaxial CCD 232 , which is fixed to a camera fixing frame 231 by bolts. The camera fixing frame 231 is fixed to the rear side of the second fixing frame 25 .

[0065] The protective cover 24 includes a transmitter head cover 241, a transparent film 242, an acrylic shell 243, a ring light 244, and an infrared glass 245. The transmitter head cover 241 is a thin-walled aluminum alloy shell, the transparent film 242 is an oil-proof and water-proof PET film, and the infrared glass 245 is a JGS3 infrared quartz glass. The transmitter head cover 241 wraps the laser transmitter head 213 of the laser unit 2, the acrylic shell 243 wraps most of the regular-shaped parts of the laser unit 2, and the transparent film 242 wraps the remaining irregular parts of the laser unit 2. The acrylic shell 243 is divided into two parts, so that all other laser parts except the laser generator 211, the transmission optical fiber 212 and the first fixed frame 25 are sealed to isolate processing dust and oil and water. The ring light 244 is fixed on the infrared glass 245 to illuminate the laser processing area and provide a clear field of view for the high-magnification coaxial CCD232. The infrared glass 245 is fixed in the center of the bottom opening of the acrylic shell 243. The high-magnification coaxial CCD232, the second reflector 223, the ring light 244 and the infrared glass 245 are coaxial.

[0066] In addition, a channel for the transmission optical fiber 212 is provided inside the machine tool spindle 12 to prevent the transmission optical fiber 212 from being damaged by rubbing against the spindle housing 127 when the machine tool spindle 12 moves on the Z-axis driver 123 .

[0067] The large-area laser milling composite processing device also includes a control unit 3, wherein a machine tool control unit 32 is fixed on the right side of the base 111 to control the movement of the machine tool, and a laser control unit 31 is fixed on the upper part of the arch frame 115 to control the laser processing. A computer 33 is placed next to the base, and the machine tool control unit 32 is connected to the laser control unit 31 and the computer 33.

[0068] The present invention also provides a large-area laser milling composite processing method with visual positioning, such as Figure 5 As shown, the following steps are included:

[0069] Fix the workpiece on the mechanical platform 11, and draw the laser processing graphics and milling processing path on the computer;

[0070] Drive the mechanical platform 11 and the machine tool spindle 12 to move the corner of the workpiece into the range of the high-magnification coaxial CCD232 lens;

[0071] The high-magnification coaxial CCD232 identifies the vertices and two sides of the workpiece corners within the lens range, obtains the X, Y difference between the center point coordinates of the high-magnification coaxial CCD232 and the position coordinates of the vertices of the workpiece corners in the current field of view, reads the current coordinates of the machine tool based on the X, Y position relationship fixed between the center of the machine tool spindle and the center of the high-magnification coaxial CCD232, converts the coordinates of the workpiece vertex in the field of view by two X, Y relative relationships to obtain the coordinates of the workpiece vertex in the absolute coordinate system of the machine tool, and establishes the workpiece coordinate system in the machine tool with the vertex of the workpiece corner as the origin;

[0072] By identifying the installation angle of the workpiece, the computer automatically transforms the drawn laser processing graphics and milling processing tool path, and rotates the laser processing graphics and milling processing tool path by the identified angle according to the installation direction to form the transformed laser processing graphics and tool path;

[0073] The computer divides the transformed laser processing graphics into grids according to the set size, obtains several rows and columns of small-sized sub-graphics, and generates the corresponding machine tool movement path according to the division size and the workpiece coordinate system position;

[0074] like Figure 6 The laser processing graphics and milling path processing and processing method are as follows: draw the original laser graphics and milling path, rotate the laser graphics and milling path by a certain angle θ, expand the edges of the original graphics and paths into new edges, divide the transformed graphics according to the set division size, and finally laser process the divided graphics in a specific order.

[0075] The laser unit 2 first moves to the top of the first segmented sub-region, and the high-magnification coaxial CCD232 retains the unprocessed surface morphology image of this region. At this time, the laser processable area has completely covered this small square segmented sub-region, and the laser processing of the sub-region pattern is carried out;

[0076] After the processing of this sub-region is completed, the high-magnification coaxial CCD232 identifies the surface morphology of this sub-region after processing, compares it with the unprocessed surface morphology image, identifies the actual processing pattern, and extracts the processing pattern at the edge segmentation of the sub-region;

[0077] The laser unit 2 moves to the next small square sub-area for processing again, identifies the images before and after processing, and extracts the actual processing graphics after both sub-areas have been processed;

[0078] Compare the appearance of the front sub-area and the rear sub-area at the segmentation point, determine the overall pattern deviation of the actual laser processing, generate the processing compensation parameter m for the galvanometer processing height and the galvanometer sub-area positioning, and automatically adjust the machine tool and galvanometer movement parameters according to the compensation parameter m when processing the next sub-area;

[0079] At the same time, the size of the laser processing molten pool at the joint of the two sub-areas is judged, and the compensation parameter n is generated to compensate the line length at the edge connection of each sub-area, reduce the influence of the laser processing molten pool overlap on the processing quality of the joint, and automatically adjust the processing parameters according to the compensation parameter n and process the next sub-area when processing;

[0080] And so on, such as Figure 7 , continuously identify and compensate the processed graphics until all segmented areas are processed, and complete the splicing processing of large-area graphics that exceed the processing range of a single laser galvanometer;

[0081] The computer sends the tool path with changed angle to the machine tool control system, and further performs milling on the surface of the workpiece after laser processing, so as to achieve high-precision matching between the laser processing graphics and the milling processing path.

[0082] Among them, the overall compensation method for extracting the line segments and sub-region patterns at the cutting position is:

[0083] Compare the front and back sub-area images to obtain the actual processed graphics, dynamically identify the line width of the actual processed graphics, generate the center line of the processed graphics, and use the line width to determine the edge endpoint position of the center line at the splicing point;

[0084] The theoretical optimal overlap of two stitching lines should be almost the end point overlap. Depending on the connection angle, there is a small overlap of the edges near the end points. Therefore, when the length of the splicing is not compensated, the actual processing image should have the smallest molten pool expansion only at the coincident end points, and the other areas are only single processing molten pools.

[0085] In actual processing, the graphics at the edge may overlap or not overlap. By comparing the images before and after processing, the splicing endpoints of two or more lines at the edge can be identified.

[0086] According to the theoretical processing graph, the theoretical processing starting endpoints of the rear sub-region after the calculation of the molten pool compensation at the end point of the front sub-region dividing line are assumed to be the a sequence (a1, a2, a3...), and the starting endpoints after marking the actual molten pool compensation are assumed to be the b sequence (b1, b2, b3...);

[0087] First, compensate for the Y-direction error of the galvanometer sub-region positioning. By comparing the theoretical processing pattern with the b-sequence endpoints, locate the actual segmentation edge of this sub-region, compare the Y-direction deviation of the midpoint of the segmentation edge of the front and rear sub-regions, and compensate the Y-axis positioning of the galvanometer in the sub-region so that the Y-axis coordinate deviation of the midpoint of the segmentation edge line close to the front and rear sub-regions is less than 20μm. Generate a sub-region compensation model after the Y-direction compensation of the galvanometer positioning. The compensated b-sequence is recorded as b'sequence.

[0088] Secondly, the rotation error of the galvanometer sub-region positioning is compensated. The angle error between the b' sequence dividing line and the a sequence dividing line is identified through the X-direction coordinate difference of the corresponding endpoints of the a and b' sequences, and the error identified by the segmentation edge line is converted to the rotation angle compensation of the sub-region galvanometer positioning center, and the corresponding Y-axis compensation caused by the angle compensation is generated by multiplying the sine value of the identified rotation angle by half of the length of the segmented area, and the Y-axis compensation is also added to the Y-axis compensation of the galvanometer positioning. After multiple compensations, the X-direction deviation of the a and b sequences is less than 20μm;

[0089] Finally, compensate for the galvanometer processing height error by using the Y-direction coordinate difference of the corresponding endpoints of the a and b' sequences. If the value is smallest near the center of the dividing line and the values ​​on both sides of the dividing line are increasing, it means that there is a deviation in the galvanometer processing height. If the Y-difference of the first pair of endpoints is greater than zero and the Y-difference of the last pair of endpoints is less than zero, then the compensation is to reduce the galvanometer processing height. If the Y-difference of the first pair of endpoints is less than zero and the Y-difference of the last pair of endpoints is greater than zero, then the compensation is to increase the galvanometer processing height. After multiple compensations, the Y-direction deviation of the a and b sequences is less than 20μm.

[0090] Multiple processing, multiple compensation, and continuous iteration of the compensation parameter m should make most of the laser processing trajectory endpoints connected and minimize the overall deviation between the laser processing sub-patterns to improve the laser splicing processing accuracy.

[0091] At the same time, the molten pool connection compensation method of each sub-pattern edge segment is:

[0092] Compare the front and back sub-area images to obtain the actual processing graphics, dynamically identify the line width of the actual processing graphics, generate the center line of the processing graphics, and use the line width to determine the edge endpoint position of the center line splicing;

[0093] The theoretical optimal overlap mode of two splicing lines should be the overlap of endpoints only, but in this case, a larger molten pool defect will appear at the connection of the two line segments, and the length of the line segments at the connection of each sub-pattern needs to be compensated to reduce the expansion area of ​​the molten pool;

[0094] Assume that the average line width of actual processing is 2r, the bending angle of the line segment to be connected on both sides of the dividing line is α, the remaining unprocessed area when the rear line segment is normally compensated is φ1, and the remaining unprocessed area when the line segment is tangent to the front line segment is φ2. According to the recognized connection angle, the inward compensation distance of the line segment is different, such as Figure 8 ;

[0095] When α≥90°, keep processing the line segments of the old sub-region to the end point of the dividing line, and shorten the line segments of the new sub-region to the region by a distance n1=r~2r, so that the connection is overlapped slightly without expanding the molten pool, and reduce the unprocessed area between the two line segment end points and the molten pool, so that φ1≤75%φ2, and obtain the most continuous connection edge;

[0096] When α<90°, keep processing part of the line segment in the old sub-area to the end point of the dividing line, and shorten the line segment in the new sub-area by a distance n2, n2>2r, so as to minimize the unprocessed area between the circular molten pools at the end points of the two line segments, so that φ1≤75%φ2, and obtain a continuous connection edge, but to prevent over-compensation, limit n2<5r;

[0097] When the front and rear sub-areas are spliced, there are multiple line segments. According to the actual processing material conditions, for multiple groups of line segments with α≥90°, n1 can be used for compensation. For multiple groups of line segments with α<90°, n2 with a suitable angle should be used for each connection point.

[0098] In the overall area compensation method, the positioning weight of α≥90° is set to 0.8, and the positioning weight of α<90° is set to 0.2. The lines with a small theoretical bending degree are mainly used to locate the pattern and judge the angle, in order to reduce the error caused by the compensation after the angle increases to the judgment of the overall compensation parameter m of the sub-area;

[0099] After multiple processing and compensation, the expansion of the molten pool of repeated single-point processing should be reduced, and the line segment connection at the cutting point should be made as smooth as possible to improve the accuracy of laser splicing processing.

[0100] In addition, the size of the small square area of ​​the automatically segmented graphics in this embodiment is 80mm×80mm.

[0101] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solution described in the implementation of the calculation method of the present invention. Ordinary technicians in the field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effect; as long as the requirements of the calculation method are met, they are all within the protection scope of the present invention.

Claims

1. A large-area laser milling composite processing device with visual positioning, characterized by: The invention comprises a laser unit (2) and a milling unit (1), wherein the laser unit (2) comprises a laser (21), an optical path (22) and a camera (23), wherein the laser (21) generates and emits laser light into the optical path (22), wherein the optical path (22) changes the laser transmission path and processes the laser light, and finally irradiates the laser light vertically downward onto the surface of a workpiece, wherein the camera (23) observes the position of the laser processing area and extracts the position information of the workpiece, wherein the milling unit (1) comprises a machine tool spindle (12) and a mechanical platform (11), wherein the mechanical platform (11) can move in the directions of the X, Y and Z axes relative to the machine tool spindle (12), wherein the laser unit (2) is fixed on the machine tool spindle (12) and moves together with the machine tool spindle (12), and wherein the workpiece is placed on the mechanical platform (11).

2. According to the large-area laser milling composite processing device with visual positioning according to claim 1, it is characterized by: The mechanical platform (11) comprises a base (111), a Y-axis drive (112), a machine tool platform (113), a heightening platform (114) and an arch frame (115). The base (111) is placed on the ground. The Y-axis drive (112) is fixed at the center of the base (111). The machine tool platform (113) is slidably arranged on the Y-axis drive (112). The Y-axis drive (112) can drive the machine tool platform (113) to move in the Y-axis direction. The heightening platform (114) is fixed at one side of the machine tool platform (113) to adjust the processing height of the workpiece. The arch frame (115) is fixed at the upper middle part of the base (111) to support the machine tool spindle (12) and the laser unit (2) thereon.

3. The large-area laser milling composite processing device with visual positioning according to claim 2 is characterized in that: The machine tool spindle (12) comprises a tool (121), a tool handle (122), a Z-direction drive (123), a nozzle (124), a spindle (125), an X-direction drive (126) and a spindle housing (127); the tool (121) is clamped in the tool handle (122); the tool handle (122) is clamped at the lower part of the spindle (125); the nozzle (124) is fixed at the lower side of the spindle (125); the nozzle (124) is used to spray cutting fluid; The spindle (125) is fixed to the X-direction driver (126) via the Z-direction driver (123); the X-direction driver (126) is fixed to the arch frame (115); the X-direction driver (126) is used to drive the Z-direction driver (123) to move in the X-axis direction; the Z-direction driver (123) is used to drive the spindle (125) to move in the Z-axis direction; the spindle housing (127) is covered outside the spindle (125) to protect the spindle (125).

4. The large-area laser milling composite processing device with visual positioning according to claim 3 is characterized by: The laser (21) comprises a laser generator (211), a transmission optical fiber (212) and a laser emitting head (213); the laser generator (211) is fixed on the machine tool spindle (12); the laser generator (211) can emit a laser beam; the transmission optical fiber (212) connects the laser generator (211) and the laser emitting head (213); the transmission optical fiber (212) can transmit the laser beam; and the laser emitting head (213) faces the laser optical path (22).

5. The large-area laser milling composite processing device with visual positioning according to claim 1 is characterized in that: The optical path (22) comprises a first reflector (221), a galvanometer (222) and a second reflector (223); the first reflector (221) refracts a laser beam emitted from a laser emission head (213) into the galvanometer (222); and the second reflector (223) is used to refract the laser beam emitted from the galvanometer (222) onto a workpiece surface.

6. The large-area laser milling composite processing device with visual positioning according to claim 1 is characterized by: The laser unit (2) further comprises a protective cover (24) and a fixing frame (25), the optical path (22) is fixed on the fixing frame (25), the fixing frame (25) is fixedly mounted on the base (111), the protective cover (24) is wrapped around the outside of the laser (21) and the optical path (22) to prevent liquid and dust from contacting the laser (21) and the optical path (22), the camera (23) is a high-magnification coaxial CCD (232), the camera (23) is fixed on the camera fixing frame (231), the camera fixing frame (231) is fixed on the second fixing frame (25), the protective cover (24) is provided with a ring light (244) and an infrared glass (245), the ring light (244) is used to illuminate the laser processing area and provide a clear field of view for the camera (23).

7. The large-area laser milling composite processing device with visual positioning according to claim 1 is characterized in that: The invention also comprises a control unit (3), the control unit (3) comprising a laser control unit (31), a machine tool control unit (32) and a computer (33), the laser control unit (31) being used to control the operation of the laser (21), the optical path (22) and the camera (23), the machine tool control unit (32) being used to control the movement and milling of the milling unit (1), the laser control unit (31) and the machine tool control unit (32) being both connected to the computer (33), and the computer (33) being used to receive information from the laser control unit (31) and the machine tool control unit (32) and to send instructions to the laser control unit (31) and the machine tool control unit (32).

8. A large-area laser milling composite processing method with visual positioning, characterized in that: Using the large-area laser milling composite processing device as claimed in claim 1, the processing method specifically includes the following steps: Step 1: fix the workpiece on the mechanical platform (11), and draw the laser processing graphics and milling processing path on the computer; Step 2: driving the mechanical platform (11) and the machine tool spindle (12) to move the corner of the workpiece to within the lens range of the camera (23); Step 3, the camera (23) identifies the vertices and two side edges of the workpiece corners within the lens range, obtains the X, Y difference between the center coordinates of the camera (23) and the position coordinates of the vertices of the workpiece corners in the current field of view, reads the current coordinates of the machine tool based on the X, Y position relationship fixed between the center of the machine tool spindle and the center of the camera (23), converts the coordinates of the workpiece vertex in the field of view by two X, Y relative relationships to obtain the coordinates of the workpiece vertex in the absolute coordinate system of the machine tool, and establishes the workpiece coordinate system in the machine tool with the vertex of the workpiece corner as the origin; Step 4: By identifying the installation angle of the workpiece, the computer automatically transforms the drawn laser processing graphics and milling processing tool path, and rotates the laser processing graphics and milling processing tool path by the identified angle according to the installation direction to form the transformed laser processing graphics and tool path; Step 5: The computer divides the transformed laser processing graphics into grids according to the set size to obtain several rows and columns of sub-graphics, and generates the corresponding machine tool movement path according to the division size and the workpiece coordinate system position; Step 6: The laser unit (2) first moves to the top of the first segmented sub-region, and the camera (23) retains the unprocessed surface morphology image of this region. At this time, the laser processable area has completely covered this sub-region, and the laser processing of the graphics of this sub-region is performed; After the processing of the sub-region is completed, the camera (23) identifies the surface morphology of the processed sub-region, compares it with the unprocessed surface morphology image, identifies the actual processed pattern, and extracts the processed pattern at the edge segmentation of the sub-region; Step 7, the laser unit (2) moves to the next sub-area for processing again, identifies the images before and after processing, and extracts the actual processing graphics after both sub-areas have been processed; Step 8: Compare the appearance of the front sub-area and the rear sub-area at the segmentation point, determine the overall pattern deviation of the actual laser processing, generate the processing compensation parameter m for the galvanometer processing height and the galvanometer sub-area positioning, and automatically adjust the machine tool and galvanometer movement parameters according to the compensation parameter m when processing the next sub-area; At the same time, the size of the laser processing molten pool at the joint of the two sub-areas is judged, and the compensation parameter n is generated to compensate the line length at the edge connection of each sub-area, reduce the influence of the laser processing molten pool overlap on the processing quality of the joint, and automatically adjust the processing parameters according to the compensation parameter n and process the next sub-area when processing; Step 9: Repeat steps 7 and 8, continuously identify and compensate the processed graphics, until all segmented areas are processed, and complete the splicing processing of large-area graphics that exceeds the processing range of a single laser galvanometer; Step 10: The computer sends the tool path with the changed angle to the machine tool control system, and further performs milling on the surface of the workpiece after laser processing to achieve high-precision matching between the laser processing graphics and the milling processing path.

9. The large-area laser milling composite processing method with visual positioning according to claim 8 is characterized in that: In step eight, the appearance of the front sub-region and the rear sub-region at the segmentation is compared to determine the overall pattern deviation of the actual laser processing, and the specific method for generating the processing compensation parameter m for the galvanometer processing height and the galvanometer sub-region positioning is: Compare the front and back sub-area images to obtain the actual processed graphics, dynamically identify the line width of the actual processed graphics, generate the center line of the processed graphics, and use the line width to determine the edge endpoint position of the center line at the splicing point; According to the theoretical processing graph, the theoretical processing starting endpoints of the rear sub-region after the calculation of the molten pool compensation at the end point of the front sub-region dividing line are assumed to be the a sequence a1, a2, a3..., and the starting endpoints after the actual molten pool compensation are marked as the b sequence b1, b2, b3...; First, compensate for the Y-direction error of the galvanometer sub-region positioning. By comparing the theoretical processing pattern with the b-sequence endpoints, locate the actual segmentation edge of this sub-region, compare the Y-direction deviation of the midpoint of the segmentation edge of the front and rear sub-regions, compensate for the Y-axis positioning of the galvanometer in the sub-region, and generate a sub-region compensation model after the Y-direction compensation of the galvanometer positioning. The compensated b-sequence is recorded as b'sequence. Secondly, the rotation error of the sub-region positioning of the galvanometer mirror is compensated. The angle error between the b' sequence dividing line and the a sequence dividing line is identified through the X-direction coordinate difference of the corresponding endpoints of the a and b' sequences, and the error identified by the segmentation edge line is converted to the rotation angle compensation of the sub-region galvanometer positioning center, and the corresponding Y-axis compensation caused by the angle compensation is generated by multiplying the sine value of the identified rotation angle by half of the length of the segmented area, and the Y-axis compensation is also added to the Y-axis compensation of the galvanometer positioning; Finally, compensate for the galvanometer processing height error by using the Y-direction coordinate difference of the corresponding endpoints of the a and b' sequences. If the value is smallest near the center of the dividing line and the values ​​on both sides of the dividing line are increasing, it means that there is a deviation in the galvanometer processing height. If the Y difference of the first pair of endpoints is greater than zero and the Y difference of the last pair of endpoints is less than zero, then the compensation is to reduce the galvanometer processing height. If the Y difference of the first pair of endpoints is less than zero and the Y difference of the last pair of endpoints is greater than zero, then the compensation is to increase the galvanometer processing height. Multiple processing and compensation are performed, and the compensation parameter m is continuously iterated to make most of the laser processing trajectory endpoints connected.

10. The large-area laser milling composite processing method with visual positioning according to claim 9 is characterized in that: In step eight, the size of the laser processing molten pool at the division point between the front sub-region and the rear sub-region is compared to determine the specific method of generating the compensation parameter n: Compare the front and back sub-area images to obtain the actual processing graphics, dynamically identify the line width of the actual processing graphics, generate the center line of the processing graphics, and use the line width to determine the edge endpoint position of the center line splicing; Assume that the average line width of actual processing is 2r, the bending angle of the line segment to be connected on both sides of the dividing line is α, the remaining unprocessed area when the rear line segment is normally compensated is φ1, and the remaining unprocessed area when the line segment is tangent to the front line segment is φ2. According to the recognized connection angle, the inward compensation distance of the line segment is different. When α≥90°, keep processing the line segments of the old sub-region to the end point of the dividing line, and shorten the line segments of the new sub-region to the region by a distance n1=r~2r, so that the connection is overlapped slightly without expanding the molten pool, and reduce the unprocessed area between the two line segment end points and the molten pool, so that φ1≤75%φ2, and obtain the most continuous connection edge; When α<90°, keep processing part of the line segments in the old sub-area to the end point of the dividing line, and shorten the line segments in the new sub-area inward by a distance n2, 5r>n2>2r, φ1≤75%φ2; When the front and rear sub-areas are spliced, multiple line segments are spliced. For multiple groups of line segments with α≥90°, n1 is used to compensate, and for multiple groups of line segments with α<90°, n2 is used to compensate.

Images