The research on various cutting technologies has been carried out at home and abroad for many years. However, more researches have been made on the problems encountered in the practical application of various cutting technologies. However, there are few studies on cutting CAD/CAM. Features, CNC laser processing machine cutting and shadow carving two processing methods. Shadow carving is based on the early "pin black and white" process based on the development and innovation of new technology, it has a strong cultural connotation, beautiful finished product effect is A new industry. However, due to the limitations of the traditional processing level and processing methods, it is difficult to achieve industrialization and large-scale development, with the development of laser technology, computer image processing technology, and the wide application of computer numerical control technology. It paved the way for shadow carving to go industrialization. This paper applies laser technology, image processing technology and computer numerical control technology to shadow carving processing, and integrates image shadow carving processing into laser processing CAD/CAM software.
1 System Architecture
The laser processing CAD/CAM system adopts a 3-layer architecture for management, as shown in Fig. 1. In Fig. 1, the upper layer is the system application layer, which is the interface between the system and the user, through which the design, analysis, simulation and processing can be completed. All tasks and real-time feedback of various result information. The design, process and other data information acquired by the system application layer is directly stored in the data layer, and the function is implemented according to the corresponding functional function of the functional layer driven by the requirements of the operation information. The middle layer is a basic functional layer that implements various functions of the system and is the core of the system, including feature modeling, editing and processing of graphics and graphics, front and rear graphics processing, shadow carving processing, etc. Various operations of basic functional layers Driven by the application layer, and its data information is obtained by the data management layer, and then stored back to the database after processing. The bottom layer is the product data management layer, to achieve a variety of data conversion, storage and management. Effective through the database management system to the database Management; through the work mode management module to effectively manage the working mode of the system, so that the system can be in multiple modes Work; exchange data with other systems via data interface module implemented as data exchange through a graphic image or the like DXF, BMP and the like.
The advantage of adopting this kind of architecture lies in that the bottom layer adopts a unified data management method. When the product model is changed, the data management mode is unchanged and has little effect on the system program; the system is hierarchical and each layer is relative. Independent, so that each layer of function expansion, the impact on other layers is very small.
Fig. 2 is the general information flow chart of the laser processing CAD/CAM system. It shows all possible data flow from product design, planning to processing. The data management system is the hub and core of the data flow, and all data information. It is stored and managed by it. The data management system is composed of two modules, a graphic data management system and an image data management system. The management of graphic elements adopts an object-oriented management mechanism to create a graphic element class for each graphic element. The object, when creating this object, gets a pointer to this information flow picture of the system of Figure 2, and manages these pointers by creating an array of dynamic object pointers. To achieve the purpose of managing all the graphical element objects. In the post-processing and other orderly requirements, the use of linked list structure for data management. CAD design system, the source of the data, including mouse, keyboard input interactive design, font characters The extraction design and the image-based drawing design. Among them, the image-based drawing design spans two data management areas of graphics and images. Various editing processing is a direct operation on various data. It needs to be performed after post processing. The data structure is changed to use the linked list structure for sequential record storage, and finally the tool trajectory list is generated. The processing simulation data can be post-processed data. Its purpose is to verify the rationality and correctness of the process planning. , It can also be obtained from the NC machining code, this time the function is to check the code. Shadow sculpture has two control methods, one for the direct control of the binary point map, the other is a binary point map Converted to digital control by continuous processing (control of NC? code format, controlled by laser processing CAD/CAM system , And transmitted to the CNC machine tool by the transmission module.
3 system components
The laser processing CAD/CAM system adopts object-oriented programming methods and feature modeling techniques to express information through objects and class modules, thus achieving system integration. According to the user's habits and the processing technology of cutting shadow carving The system is divided into the following five major functional modules.
3.1 System Interface Module
The system interface includes data interface and network interface. The data interface is to make this system compatible with other general systems, so the system should have as many data file interfaces as possible. The data file interface supported by this system has a graphical interface. DXF file format, image interface BMP, JEPJ, GIF, TIFF, TGA and other image format files, as well as automatic extraction of vector text outlines. The network interface is to achieve network numerical control technology, change the configuration of resources, and achieve direct communication with the machine tool .
3.2 CAD drawing module
The CAD drawing includes three parts: drawing, design, and editing. The drawing part describes the outline by providing various graphics and floor patterns, and overcomes various shortcomings that are directly driven by the vectorization of the image. It can be easily inserted and deleted. Perform various operations on the basemap, such as real-time dynamic zooming, position adjustment, contrast adjustment, etc. The design section provides a friendly human-machine interface and interactively performs CAD part drawing, and plays a role in the CAD system. The important role. Through it can design a variety of engineering parts drawing This class can easily provide a variety of drawing primitives, driven by the menu or icon, can be operated by the mouse, but also through the keyboard for a variety of data information Delightful, with various features of the capture function.
The editing part can be easily selected first, and the various graphic elements can be easily selected. The mouse drags the feature points of the selected graphic element, changes the geometric parameters, position, etc. of the graphic element, and achieves dynamic modification'. The selected graphic element can be edited. Copy, cut, paste, translate, delete, mirror, rotate, zoom, and more.
The image processing function is to adjust and process the image according to requirements to satisfy the drawing or shadow carving halftone processing. Among them, the gray scale conversion has three methods: the average value method, the maximum value method and the weight value method. The gray scale adjustment is on the gray After the degree conversion, the grayscale of the screen is adjusted, an adjustment dialog box is popped up, the data input can be adjusted by adjusting the grayscale adjustment curve, or the mouse can drag and adjust, and the distribution of the grayscale can be known by displaying the histogram. The brightness of the contrast adjustment basis. Rotation and scaling is specified through the form of a dialog box rotation angle and scaling. Image bit conversion provides conversion between 1,2,4,8 bits. Delete image is applied in the tracing operation, After the drawing operation is complete, the background image should be deleted; the sharpening enhancement is to enhance the edges. In the tracing operation, the rendered graphics are more accurate; and in the shadow carving processing, the edge details blurred in the halftone processing can be compensated.
3. 4 CAM processing module
According to product information generated after modeling and manufacturing requirements, human-machine interaction or automatic decision-making of auxiliary machining lines, nesting relationships, machining sequences, offset directions, offsets, etc. for machining of parts. Toolpaths in path offsets The offset calculation generates the required tool machining path and can directly output the track parameter information. It is received and recognized by the NC automatic programming system. The NC automatic programming system receives and recognizes the tool position information provided by the system and converts it into Parts of the NC machining program.
3. 3 shadow carving processing module
The basic principle and process of laser shadow carving processing is: in the image processing system, the original image file is edited and preprocessed, and then the halftone technology is used to generate the black and white binary image file in the laser shadow carving mode. The computer control system reads The binary image file controls the XY axis to drive the laser head to scan and move, and the 0 and l values ​​of the black and white binary image control the laser on or off. The laser beam is transmitted through the optical mechanism and focused on the surface of the material, so that the material of the action point is Rapidly melting, gasifying and ejecting, similar to hand-carved pits. Therefore, this module mainly performs various halftone methods on the image, including error diffusion method, dithering method, jitter diffusion method, and threshold method. Error diffusion method According to the different filters, it can be divided into Stucki, Burkes, Sierrk, Larvis, Stevenson and Steinberg methods. The jitter diffusion method sets the template size according to the requirements, and finally obtains the shadow carving binary point map or the graphic design required for shadow carving processing. The image of the bottom plate.
4 System Operation Example
Figure 3 shows an example of the tool path generated by the laser CAD/CAM system software after the DXF file is edited. First, the DXF graphics of the tuneer are sorted and then the dialog box generated by the trajectory is set. The auxiliary line is already in the graphic. Contains or is added after the offset to determine how the auxiliary lines are added; from the processing path and offset direction of the machining trajectory, specify whether they are manually interactively completed or automatically discriminated by the system. The option specifies that all units are clockwise or counterclockwise, and the offset direction is offset outwards by the outer contour and the inner contour is offset inwards; the loser must offset the amount of compensation, etc. If the processing direction and offset When the direction of movement is manual interactive, first select a graphic element on the contour line, select this contour element, select the processing direction according to the arrow prompt, and then select the offset direction by pressing the arrow to complete the deviation of a contour element. Generated. If the processing auxiliary line is added after the offset, the auxiliary line can be added by the drawing tool and screen capture. The tool path path is composed of 3 processing units. The auxiliary line is added after the offset, and the processing direction of the offset is added. The offset direction is determined automatically by the system. The inner layer is the contour of the workpiece and the outer layer is the tool path. The series wiring between the closed loops is the processing auxiliary line such as the cutter line, the retracting line, and the transition line.
Using the object-oriented programming method, a set of laser processing CAD/CAM software system with two functions of cutting and shadow carving image generation was developed. This system has the functions of DXF file importer interface, graph wooing and editing, tool path generation and other functions. , NC code and shadow image generated by the application of self-developed CNC laser processing system, can be processed to a satisfactory product, widely used in laser processing machines and other CNC cutting machine.
1 System Architecture
The laser processing CAD/CAM system adopts a 3-layer architecture for management, as shown in Fig. 1. In Fig. 1, the upper layer is the system application layer, which is the interface between the system and the user, through which the design, analysis, simulation and processing can be completed. All tasks and real-time feedback of various result information. The design, process and other data information acquired by the system application layer is directly stored in the data layer, and the function is implemented according to the corresponding functional function of the functional layer driven by the requirements of the operation information. The middle layer is a basic functional layer that implements various functions of the system and is the core of the system, including feature modeling, editing and processing of graphics and graphics, front and rear graphics processing, shadow carving processing, etc. Various operations of basic functional layers Driven by the application layer, and its data information is obtained by the data management layer, and then stored back to the database after processing. The bottom layer is the product data management layer, to achieve a variety of data conversion, storage and management. Effective through the database management system to the database Management; through the work mode management module to effectively manage the working mode of the system, so that the system can be in multiple modes Work; exchange data with other systems via data interface module implemented as data exchange through a graphic image or the like DXF, BMP and the like.
The advantage of adopting this kind of architecture lies in that the bottom layer adopts a unified data management method. When the product model is changed, the data management mode is unchanged and has little effect on the system program; the system is hierarchical and each layer is relative. Independent, so that each layer of function expansion, the impact on other layers is very small.
Figure 1 System Architecture Diagram
Fig. 2 is the general information flow chart of the laser processing CAD/CAM system. It shows all possible data flow from product design, planning to processing. The data management system is the hub and core of the data flow, and all data information. It is stored and managed by it. The data management system is composed of two modules, a graphic data management system and an image data management system. The management of graphic elements adopts an object-oriented management mechanism to create a graphic element class for each graphic element. The object, when creating this object, gets a pointer to this information flow picture of the system of Figure 2, and manages these pointers by creating an array of dynamic object pointers. To achieve the purpose of managing all the graphical element objects. In the post-processing and other orderly requirements, the use of linked list structure for data management. CAD design system, the source of the data, including mouse, keyboard input interactive design, font characters The extraction design and the image-based drawing design. Among them, the image-based drawing design spans two data management areas of graphics and images. Various editing processing is a direct operation on various data. It needs to be performed after post processing. The data structure is changed to use the linked list structure for sequential record storage, and finally the tool trajectory list is generated. The processing simulation data can be post-processed data. Its purpose is to verify the rationality and correctness of the process planning. , It can also be obtained from the NC machining code, this time the function is to check the code. Shadow sculpture has two control methods, one for the direct control of the binary point map, the other is a binary point map Converted to digital control by continuous processing (control of NC? code format, controlled by laser processing CAD/CAM system , And transmitted to the CNC machine tool by the transmission module.
3 system components
The laser processing CAD/CAM system adopts object-oriented programming methods and feature modeling techniques to express information through objects and class modules, thus achieving system integration. According to the user's habits and the processing technology of cutting shadow carving The system is divided into the following five major functional modules.
3.1 System Interface Module
The system interface includes data interface and network interface. The data interface is to make this system compatible with other general systems, so the system should have as many data file interfaces as possible. The data file interface supported by this system has a graphical interface. DXF file format, image interface BMP, JEPJ, GIF, TIFF, TGA and other image format files, as well as automatic extraction of vector text outlines. The network interface is to achieve network numerical control technology, change the configuration of resources, and achieve direct communication with the machine tool .
3.2 CAD drawing module
The CAD drawing includes three parts: drawing, design, and editing. The drawing part describes the outline by providing various graphics and floor patterns, and overcomes various shortcomings that are directly driven by the vectorization of the image. It can be easily inserted and deleted. Perform various operations on the basemap, such as real-time dynamic zooming, position adjustment, contrast adjustment, etc. The design section provides a friendly human-machine interface and interactively performs CAD part drawing, and plays a role in the CAD system. The important role. Through it can design a variety of engineering parts drawing This class can easily provide a variety of drawing primitives, driven by the menu or icon, can be operated by the mouse, but also through the keyboard for a variety of data information Delightful, with various features of the capture function.
The editing part can be easily selected first, and the various graphic elements can be easily selected. The mouse drags the feature points of the selected graphic element, changes the geometric parameters, position, etc. of the graphic element, and achieves dynamic modification'. The selected graphic element can be edited. Copy, cut, paste, translate, delete, mirror, rotate, zoom, and more.
Figure 2 System Information Flow Chart
The image processing function is to adjust and process the image according to requirements to satisfy the drawing or shadow carving halftone processing. Among them, the gray scale conversion has three methods: the average value method, the maximum value method and the weight value method. The gray scale adjustment is on the gray After the degree conversion, the grayscale of the screen is adjusted, an adjustment dialog box is popped up, the data input can be adjusted by adjusting the grayscale adjustment curve, or the mouse can drag and adjust, and the distribution of the grayscale can be known by displaying the histogram. The brightness of the contrast adjustment basis. Rotation and scaling is specified through the form of a dialog box rotation angle and scaling. Image bit conversion provides conversion between 1,2,4,8 bits. Delete image is applied in the tracing operation, After the drawing operation is complete, the background image should be deleted; the sharpening enhancement is to enhance the edges. In the tracing operation, the rendered graphics are more accurate; and in the shadow carving processing, the edge details blurred in the halftone processing can be compensated.
3. 4 CAM processing module
According to product information generated after modeling and manufacturing requirements, human-machine interaction or automatic decision-making of auxiliary machining lines, nesting relationships, machining sequences, offset directions, offsets, etc. for machining of parts. Toolpaths in path offsets The offset calculation generates the required tool machining path and can directly output the track parameter information. It is received and recognized by the NC automatic programming system. The NC automatic programming system receives and recognizes the tool position information provided by the system and converts it into Parts of the NC machining program.
3. 3 shadow carving processing module
The basic principle and process of laser shadow carving processing is: in the image processing system, the original image file is edited and preprocessed, and then the halftone technology is used to generate the black and white binary image file in the laser shadow carving mode. The computer control system reads The binary image file controls the XY axis to drive the laser head to scan and move, and the 0 and l values ​​of the black and white binary image control the laser on or off. The laser beam is transmitted through the optical mechanism and focused on the surface of the material, so that the material of the action point is Rapidly melting, gasifying and ejecting, similar to hand-carved pits. Therefore, this module mainly performs various halftone methods on the image, including error diffusion method, dithering method, jitter diffusion method, and threshold method. Error diffusion method According to the different filters, it can be divided into Stucki, Burkes, Sierrk, Larvis, Stevenson and Steinberg methods. The jitter diffusion method sets the template size according to the requirements, and finally obtains the shadow carving binary point map or the graphic design required for shadow carving processing. The image of the bottom plate.
4 System Operation Example
Figure 3 shows an example of the tool path generated by the laser CAD/CAM system software after the DXF file is edited. First, the DXF graphics of the tuneer are sorted and then the dialog box generated by the trajectory is set. The auxiliary line is already in the graphic. Contains or is added after the offset to determine how the auxiliary lines are added; from the processing path and offset direction of the machining trajectory, specify whether they are manually interactively completed or automatically discriminated by the system. The option specifies that all units are clockwise or counterclockwise, and the offset direction is offset outwards by the outer contour and the inner contour is offset inwards; the loser must offset the amount of compensation, etc. If the processing direction and offset When the direction of movement is manual interactive, first select a graphic element on the contour line, select this contour element, select the processing direction according to the arrow prompt, and then select the offset direction by pressing the arrow to complete the deviation of a contour element. Generated. If the processing auxiliary line is added after the offset, the auxiliary line can be added by the drawing tool and screen capture. The tool path path is composed of 3 processing units. The auxiliary line is added after the offset, and the processing direction of the offset is added. The offset direction is determined automatically by the system. The inner layer is the contour of the workpiece and the outer layer is the tool path. The series wiring between the closed loops is the processing auxiliary line such as the cutter line, the retracting line, and the transition line.
Figure 3 Tool Trajectory Generation Diagram
Figure 4 sculpture image rendering effect
Using the object-oriented programming method, a set of laser processing CAD/CAM software system with two functions of cutting and shadow carving image generation was developed. This system has the functions of DXF file importer interface, graph wooing and editing, tool path generation and other functions. , NC code and shadow image generated by the application of self-developed CNC laser processing system, can be processed to a satisfactory product, widely used in laser processing machines and other CNC cutting machine.
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