Parametric design of the hottest 3D model and Real

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The realization of three-dimensional model parametric design and numerical control machining simulation

with the improvement of the automation degree of mechanical manufacturing industry, the competition of product production is becoming increasingly fierce. People use the excellent functions of CAD/CAM technology to realize the functions of product aided design and manufacturing, so as to greatly shorten the production cycle and reduce the production cost of products. SolidWorks is a mainstream 3d design software based on Windows platform, which is widely used in product design in various industries. It adopts a feature-based parametric model system to provide a platform for the integration of product design, analysis and manufacturing. MasterCAM is a CAD/CAM integrated software developed by CNC software company in the United States. It has low requirements for hardware, flexible operation, and good cost performance. Especially in CNC programming, it is fast and convenient, and is widely used in small and medium-sized manufacturing enterprises. In practical work, designers use solidwork1, metal tensile testing machine: metal material tensile strength big s software to design parts, then import the part model into MasterCAM software to compile the part tool path, and automatically generate NC code, which greatly improves the work efficiency and effectively ensures the accuracy of part processing. Taking cylindrical cam as an example, the author expounds in detail the realization process from parametric design of three-dimensional model to automatic programming and machining simulation

1 processing parts and process analysis

Figure 1 shows the cylindrical cam part diagram, with cylindrical diameter d=254mm, cylindrical height h=203.20mm, inner hole radius r=80.8mm, roller diameter dt=30.25ram, and cam groove depth v=20.65mm

the cylindrical cam groove is an equal width groove surrounding the cylindrical surface. During machining, the range of milling along the circumferential surface of the cylindrical cam by the cutter is often greater than 360 °. It is advisable to use a four-axis or three-axis vertical CNC milling machine with a CNC turret for machining. The bottom of the cylindrical cam groove is usually of equal depth on each section. The cylindrical end mill with a diameter of 20mm is selected after repeated several times according to the groove width and shape. Cylindrical cam milling meets the standard: before machining, it is usually a solid cylinder, which needs to go through the processes of slotting - rough machining - semi finishing - finishing

because the width of the cam groove is greater than the actual tool diameter, except for rough machining, the other processes adopt non equal diameter machining, and the offset value of the tool path relative to the rough machining path to both sides is ± 5.125mm; Among them, the step spacing of semi finishing tools is 2mm, and the tool is moved twice; The step spacing of finishing tools is 1.125mm, and the tool is moved once; It is completed in 6 times (3 times on one side)

2 parametric 3D design

2.1 camtrax plug-in function

camtrax is a third-party software with windows interface applied to SolidWorks software, which is used to help designers accurately and effectively build various types of cam solid models. Main functions of camtrax plug-in:

(1) provide various cam types and main motion modes (clockwise, counterclockwise) such as straight line, disc, cylinder, etc. the contact forms between push rod and cam can be groove type, contour contact, inner contour contact, and the follower can be centripetal direct acting push rod, eccentric direct acting push rod, and swing push rod

(2) the follower motion law and load data can be customized. The optional cam motion laws are: ① the cam does not move; ② Barrel harmonic motion law; ③ Sinusoidal acceleration; ④ Corrected sinusoidal acceleration; ⑤ Corrected trapezoidal acceleration; ⑥ Sine constant speed compound motion law; ⑦ Sine harmonic compound motion law; ⑧ Eighth order polynomial motion law; ⑨ External data file (TXT format), two columns: the first column is the cam angular displacement, with an increment of 0.1 °, and the second column is the corresponding follower displacement. The load data that can be input are: ① elastic modulus of follower and elastic modulus of cam; ② Weight acceleration data, external force action data; ③ Cam speed; ④ Spring data. (3) The results of motion analysis can be output to Excel files

2.2 construction of cam solid model

after setting the basic parameters of cylindrical cam and defining the motion law parameters of follower in camtrax software, SolidWorks software uses the curve function to automatically draw the theoretical contour curve and the actual contour curve of cam, and finally generates the three-dimensional solid of cam through cutting and sampling operation

2.3 data exchange of part model

after completing the design of cam solid model in SolidWorks, it is necessary to import solid parts into MasterCAM for tool path setting of NC machining. Through the MasterCAM direct plug-in in the SolidWorks toolbar, users can open the solid model in MasterCAM when using SolidWorks, so as to ensure the integrity of the solid model parameters and prepare for the subsequent tool path settings

3 NC machining and Simulation of part models

3.1 machining settings of MasterCAM x

(1) rough machining

select "toolpaths" - "contour toolpath" command, "chain" (in series) select the cam groove center curve and confirm; In the contour processing dialog box, select the end milling cutter with a diameter of 20mm, and set the parameters of the rotating shaft, speed, feed and so on; Set the computer compensation and controller compensation to off, set the safety height, fallback height, feed height, machining depth, tool introduction and export and other parameters, and finally determine. The system automatically generates the rough machining tool path

(2) semi finishing and finishing

select "toolpaths" - "transform toolpath" command, select the conversion type as "translate", and check "create new operation management item"; Open the "translation" operation parameter dialog box, select "distance between two points", set the translation parameters, and generate the semi precision machining tool path with a step distance of 2mm, a step distance of 1.125mm, and an energy machining tool path with a step distance of 1 along both sides of the groove center line. Finish the tool path definition of rough and finish machining of cam groove

3.2 automatic programming and machining simulation

in the "operation manager", select all defined rough and finish machining paths for a total of 7 times, click "post processing", select the path to save the NC program, and the system automatically generates the NC code (Figure 6). Click "solid verification" to enter the solid cutting simulation, which can not only verify the correctness of the generated NC program, but also realistically simulate the actual machining process of parts (sincerely hope that the control system of the experimental machine will be more perfect in the future development! Figure 7)

4 conclusion

through the machining example of cylindrical cam parts, this paper introduces the detailed process from 3D model construction to automatic programming and machining simulation by using mainstream CAD/CAM software such as SolidWorks and MasterCAM. At the same time, mastering the conversion of two software in the process of product design and manufacturing can effectively play the function of software and improve the quality and efficiency of product design and manufacturing

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