Plate parts are more complex plate parts composed of multiple planes, chamfers, deep holes, threaded holes, grooves, and outer contours. It is characterized by the fact that the basic shape of the part is in the form of a long strip, and the surface of the part brings together a variety of typical surfaces. When machining, the number of clamping is generally less, but the tools used are generally more, and the preparation program is more cumbersome. Before processing, it is necessary to make adequate preparations, including drawing analysis, determining the processing technology, selecting the machine tool model, selecting the size of the blank, determining the cutting depth, taking the tool route and processing sequence, etc., and the preparatory work in the early stage is more complicated.
Directory. Prolegomenon. 2
Chapter 1 Design and 3D Modeling of Plate Parts. 3
1.1. Introduction and features of the software. 3
1.2. Modeling of plate parts. 3
Chapter 2 Process Analysis of Parts. 5
2.1. The basic characteristics of the processing technology. 5
2.1.1. Selection of parts and materials. 5
2.1.2. Selection of CNC machine tools. 5
2.1.3. Selection of fixtures. 6
2.2. The division of processes and work steps. 6
2.2.1. Division of processes. 6
2.2.2 Published Divisions. 7
2.3. The selection of tools and the determination of cutting amount. 7
2.4. Determination of the tool point. 8
2.5. Determination of processing route. 8
2.5.1. Formulate a processing plan. 8
2.5.2. Design the feed route. 8
Chapter 3 Preparation and processing of CNC machining programs. 10
3.1. Determination of the workpiece coordinate system. 10
3.2. Compile CNC machining programs. 10
3.3**Processing. 11
Chapter 4 Error Analysis. 13
Conclusion. 14 Acknowledgments. 15
References. 16
Plate parts are one of the typical parts commonly found in CNC machining. It has a wide range of applications, and many factors need to be considered in the machining process, including the analysis of drawings (two-dimensional drawings), the selection of CNC machine tools suitable for processing the part, the selection of tools and specifications used in processing, the selection of appropriate cutting amounts, and so on. It can be seen from this that CNC machining is a complex technology. It takes a lot of learning and proficiency to complete the task while maintaining safety. Therefore, as a member of the CNC industry, we should strive to improve our professional level, constantly exercise our practical skills, and strive to become a CNC technical talent with all-round development.
This topic is the last practical teaching link for cultivating engineering students, which requires students to comprehensively use the knowledge of basic courses, professional basic courses and professional courses to solve the problems encountered in practical processing, and is the basic ability training that must be possessed by engineering and technical personnel.
Through the graduation project, students will meet the following requirements:
Consolidate and improve drawing recognition, three-dimensional CDA modeling, CNC machining process parameter selection, CNC machining programming, and improve students' ability to comprehensively apply the knowledge they have learned.
Cultivate students' ability to select reference books and consult manuals and literature according to the needs of the topic.
Students will master the use of CAD by completing various tasks in the project, such as: modeling of plate parts, selection of machine tools, selection of tools, determination of machining parameters, application of M99 instructions, use of G** generation, etc.
Understand the engineering and technical specifications, and be able to write design instructions according to the requirements of the graduation project assignment, be able to correctly select suitable parts, and verify the correctness of the design scheme through **software**.
Proficient in using 3D CAX software for part modeling, processing simulation, and G** generation.
Cultivate a serious work style and scientific attitude. Through the practice of graduation project, it helps students gradually establish a correct view of production, economy and overall situation.
1) Introduction to SOLIDWORKS: Founded in 1993 by the vice president of technology of PTC and the vice president of CV, SOLIDWORKS is headquartered in Concord County, Massachusetts, Massachusetts. Since the launch of the first SOLIDWORKS 3D mechanical design software in 1995, it has offices around the world and sells and distributes the product in 140 countries through 300 distributors. SOLIDWORKS is the world's first Windows-based 3D CAD system, and because of its technological innovation in line with the development trend and trend of CAD technology, SOLIDWORKS has become the most profitable company in the CAD CAM industry in two years.
2) SOLIDWORKS features: SOLIDWORKS software is powerful and has a wide range of components. Powerful, easy-to-learn, easy-to-use, and technological innovation are the three major features of SOLIDWORKS, making SOLIDWORKS the leading and mainstream 3D CAD solution. SOLIDWORKS offers different design options, reducing errors in the design process, and improving product quality. SOLIDWORKS not only provides such powerful capabilities, but is also easy to use, easy to learn, and easy to use for every engineer and designer.
3) CAXA Introduction: CAXA Manufacturing Engineer is a full-Chinese, 3D CAD CAM software for CNC milling machines and machining centers developed by Beihang Software ***. CAXA manufacturing engineers are based on the microcomputer platform, using original windows menus and interactive methods, full Chinese interface, easy to learn and operate, and ** low. CAXA manufacturing engineers can generate 3-5 axis machining** that can be used to machine parts with complex 3D surfaces. Functional featuresConvenient featuresSolid modelingPowerful NURBS freeform modelingFlexible curved solid composite modeling, unique processing**and**verification Machining process control CAXA manufacturing engineers provide a wealth of process control parameters, which can easily control the machining process, so that the programmer's experience can be fully reflected. The processing process control fully supports a variety of mainstream machine tool control systems such as Siemens and FANUC. The post-processor provided by CAXA's manufacturing engineers can directly output G** control commands without the need to generate intermediate files. The system can not only provide the post-processing format of the common CNC system, but also the user can define the post-processing format of the dedicated CNC system. A detailed processing process list can be generated to facilitate the application and management of G** files.
The material of the parts is aluminum alloy, and the blank size is 140mmx115mmx35mm. The surrounding area is processed to the requirements of the sample drawing, and the lower surface is processed, and the processing content is the outer contour of the upper plane and two steps. It is required to formulate the correct processing technology plan, select reasonable props and cutting amounts, paranoid CNC machining procedures and process parts that meet the requirements of the drawing.
Figure 1: Generate a sketch Figure 2: Extrude boss.
Figure 3: Creating a Sketch Figure 4: Drawing a Sketch.
Figure 5 Extrude Boss Figure 6 Create a sketch.
Figure 7: Sketch Figure 8: Complete plate modeling.
The CNC machine tool processing technology is basically the same as the ordinary machine tool processing body in principle, but the whole process of CNC machining is carried out automatically, so it has its characteristics.
1.The process content of CNC machining is more complex than that of ordinary machine tool processing, this is because CNC machine tools are expensive, if only simple processes are processed, it is not economical to be economical, so more complex processes are usually arranged on CNC machine tools, and even those processes that are difficult to complete on ordinary machine tools.
2.The preparation of CNC machine tool processing procedures is more complex than that of ordinary machine tool process procedures. This is because in the processing technology of ordinary machine tools do not have to consider the problem, such as the arrangement announced in the process, the tool point, the tool change point, and the determination of the tool route, etc., in CNC machining, all this has become a fixed program content without exception, because of this characteristic, the correctness and rationality of the processing program are extremely high, and there can be no slightest error, otherwise the processing can not be qualified parts.
Selection of part materials
Aluminum alloy is the most widely used non-ferrous metal structural material in industry, and has been widely used in aviation, aerospace, automotive machinery manufacturing, shipbuilding and chemical industries. With the rapid development of science and technology and industrial economy, the demand for aluminum alloy welded structural parts is increasing, so that the research on the weldability of aluminum alloy is also deepening. The wide application of aluminum alloy has promoted the development of aluminum alloy welding technology, and the development of welding technology has expanded the application field of aluminum alloy, so the welding technology of aluminum alloy is becoming one of the hot spots of research.
Selection of CNC machine tools
Vertical numerical control milling machine, as shown in Figure 9, spindle is perpendicular to workpiece table, workpiece clamping is convenient, spindle and workpiece table surface are perpendicular, workpiece clamping is convenient, and the situation of workpiece is convenient to observe during processing, but not convenient for chip removal. Vertical CNC milling machines can be divided into three types: small and large. but not convenient for chip removal. Vertical CNC milling machines can be divided into three types: small, medium and large. The small one adopts the way that the worktable moves and lifts without the spindle moving;The small one adopts the way that the worktable moves and lifts without the spindle moving;The medium-sized adopts longitudinal and transverse movement mode, and the spindle can move up and down in the vertical direction;and lateral movement, and the spindle can move up and down in the vertical direction;Large-scale, considering many technical factors such as expanding the line, reducing the floor space and maintaining rigidity, generally adopt gantry movement, its main shaft can move horizontally and vertically in the gantry, and the gantry frame is longitudinal movement along the bed. The spindle can move horizontally and vertically along the gantry, and the gantry moves longitudinally along the bed.
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Fig.9. XK0824 CNC milling machine.
Selection of fixtures
Machine-used flat-mouth vise is a general accessory for machine tools, which is used with the workbench to fix, clamp and position the workpiece in the processing process. The machine flat vise is composed of a torso, movable jaws, nuts, screws and other components. According to its structure and use, it can be divided into general flat vise, angle pressing machine with flat vise, tilting machine with flat vise, high-precision machine with flat vise, force booster machine with flat vise, etc., is the main fixture of planer, milling machine, drilling machine, grinding machine, slotting machine, widely used in milling machine, drilling machine and other processing of various planes, grooves, angles, etc.
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Fig. 10: Flat-nosed vise for machine.
Division of operations
1) the division of the process: processing parts on the CNC machine tool, the process can be relatively concentrated, in a clamping as far as possible to complete most or all of the process, first of all, the parts to be processed should be considered according to the parts drawing, whether the processed parts can be completed on a CNC machine tool processing work, if not, which part should be decided which part is processed on the CNC machine tool, which part is processed on other machine tools, that is, the parts processing process is planned.
Published divisions
2) the division of work steps: mainly from the two aspects of machining accuracy and efficiency, in a process often need to adopt different tools and cutting amounts, to process different surfaces. In order to facilitate the analysis and description of the complex process of hinginge, it is subdivided into steps in the process, and the following takes the machining center as an example to illustrate: 1) The same surface is completed sequentially according to rough machining, semi-finishing, and finishing or all the processed surfaces are separated according to rough first and then finishing;2) For parts with both milled face and boring, the face can be milled first and then bored. Dividing the work steps in this way can improve the accuracy of the hole, because the cutting force is large during milling, and the workpiece is prone to deformation. Mill the surface first and then boring the hole, so that it has a period of time to recover, reducing the impact on the accuracy of the hole caused by deformation;3) Divide the work step according to the tool, the rotation time of the worktable of some machine tools is shorter than the tool change time, and the work step can be divided according to the tool to reduce the number of tool changes and improve the processing efficiency. In short, the division of process and work steps should be comprehensively considered according to the structural characteristics and technical requirements of specific parts.
The selection of the cutting amount is milling, because the amount of back or side of the cutter has little impact on the tool life, and the cutting speed has the greatest impact, and the roughing mainly considers the production efficiency, and the finishing mainly considers the cost of machining accuracy and efficiency. Therefore, the order of selection of roughing cutting amount is: firstly, select a larger amount of back eating cutter or a side eating amount, then select a faster feed rate, and finally determine a lower cutting speed;For finishing, a smaller feed rate and a higher spindle speed are selected to improve the machining accuracy.
Table 1 CNC machining process card.
The tool setting point is selected at the intersection point between the center of the 100mm arc of the boss on the workpiece and the upper surface.
For CNC machine tools, the processing route refers to the movement trajectory and direction of the tool machining center, and the reasonable selection of the processing route can not only improve the cutting efficiency but also improve the surface roughness of the parts. The following aspects should be considered in determining the processing route:
1) Minimize the time of advance and exit and other auxiliary time.
2) When milling the contour of the part, try to use the forward milling method to improve the surface accuracy.
3) The position of advance and retract is selected in a less important position, and the tool is advanced and retracted along the tangential direction of the workpiece to avoid knife marks.
4) Process the outer contour first, and then process the inner contour.
Develop a processing plan
Milling on the plane to ensure that the thickness of the plate size is 34mm rough milling on the side and bottom surface of the boss, leaving a finishing allowance of 1mm on the side and a finishing allowance of 0 on the bottom surface5mm rough milling of the lower boss side, leaving a finishing allowance of 1mm on the side, and milling the bottom surface to the size of rough milling the side and bottom of the boss Finish milling the side of the lower boss.
Design the feed route
In order to facilitate the calculation, the origin of the workpiece coordinate system is set at the upper plane of the center of the boss arc on the workpiece. The design of the workpiece upper plane milling feed route is shown in Fig. 11, the milling feed route of the outer contour of the side of the upper boss is shown in Fig. 12, and the milling of the outer contour of the side of the lower boss is shown in Fig. 13.
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Fig. 11 upper surface processing route design Fig. 12 upper boss side outer contour processing route.
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Fig. 13: Machining route of the outer contour of the side of the lower boss.
According to the part drawing and the process route, the coordinate value of each processing point on the upper surface is obtained as shown in Table 2, the machining coordinate value of each point of the side outer contour of the upper boss as shown in Table 3, and the processing coordinate value of each point of the outer contour of the side of the lower boss as shown in Table 4.
Table 2: The coordinate values of each processing point on the upper surface.
Table 3: Machining coordinate values of each point of the outer contour of the side of the boss.
Table 4: Machining coordinates of each point of the outer contour of the side of the lower boss.
This paper adopts manual programming, and the intersection point between the center of the 100mm arc of the boss on the workpiece and the upper surface is the origin of the workpiece coordinate system. First of all, the part diagram is analyzed, the processing process is analyzed, and then the mathematical processing is carried out, the node and base point coordinates are calculated, and then the program list is written out, which is input into the machine tool system through the operation panel, and the machining process is verified by the trajectory **, and finally the program can be run to process the parts.
Fig.14. Machining tool.
Some of the processing procedures are as follows:
o0001n1g17 g90 g40 g80 g49 g21
n3g91 g28 z0
n5 m06 t01
n10g90g54g00z100.000
n12s3000m03
n14x0.000y0.000z100.000
n16x-53.000y-40.000
n18z0.500
n20g01z-4.500f100
n1970x-6.842y18.884
n1972x-6.796y18.814
n1974x-7.393y18.589
n1976x-7.420y18.578
n1978g03x-18.792y6.801i7.463j-18.585
n1980g01z-10.000f100
n1982g00z100.000
n1984x0.000y0.000
n1986m05
n1988m30
1) Turn on the machine and go back to the reference point.
2) Establish the program number in turn, and input the programmed program into the machine tool from the MDI panel for tool trajectory simulation, and post-processing without error.
3) Clamp the blank with a flat-nosed vise and install the cutter.
4) Use the trial cutting method to set the tool compensation.
5) Arrange processing to the required size according to the process route, as shown in Figure 10.
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Figure 15** Processing.
After three months of hard work, the modeling and processing design scheme of the plate parts was finally completed, in the whole modeling process there have been a lot of problems, but they have been successfully solved with the help of teachers and classmates, in the continuous learning process I realized that writing is a continuous learning process, from the beginning of writing Yes, I realized that I finally had a deep understanding of the plate parts, I realized the importance of practice for learning, before I only understood the theory, without practical investigation, the understanding of knowledge was not clear enough, through this **, truly achieved the combination of theory and practice.
Through my graduation project, I deeply realized that to do a complete job well, I need to have a systematic way of thinking and methods, be patient with the problems to be solved, and be good at using the existing resources to enrich myself. At the same time, I also deeply realize that when dealing with a new thing, we must consider it as a whole, and then do the next step after completing one step, so that it can be more effective. It has helped me a lot with my personal CNC technology and the skills to complete machining independently, and it has made me like CNC technology even more. It made me fully see my own shortcomings, and made my skills improve by leaps and bounds.