With the rapid development of computer-aided design technology and the continuous improvement of functions, the design methods and means of engineering and technical personnel are more and more abundant. Especially the wide application and popularization of 3D CAD/CAM software has made modern mechanical product design gradually enter the era of 3D design. The 3D design is visual, intuitive, accurate and fast. It can play a decisive role in the design of new product development, structural analysis, product performance evaluation, determination and optimization of physical prototype parameters, and a successful development of new products. , providing strong technical support.
Solidworks/Motion is a parametric 3D solid modeling software based on the Windows environment. For the majority of engineering and technical personnel to provide seamless integration of solid modeling, finite element analysis and optimization design, virtual assembly, 3D motion simulation, motion interference inspection, process specification generation, CNC machining, 3D solid image transformation in a single Windows interface Dimensional functions such as dimensional engineering drawings, product data sharing and integration.
This paper takes a model of three-axis analog rocking and re-creating mechanism as an example, and introduces the process of three-axis simulation of rocking and resurfacing mechanical device in three-dimensional solid modeling, assembly, three-dimensional motion simulation and motion component interference inspection using SolidWorks/Motion software. method.
The three-axis simulation rocking and recurring mechanical device is mainly composed of an inner ring, a middle ring, an outer ring and a base, as shown in FIG. 1 .
Figure 1 Schematic diagram of a three-axis simulation swinging recurrent mechanical device
3D solid modeling design
The measurement system of the three-axis simulation sway-reproduce device has relatively high precision. Therefore, when designing the mechanical structure of the three-axis simulation sway-reproduce device, it is necessary to ensure that the rigidity of the mechanical structure can meet the accuracy requirements of the measurement system, and also To optimize the structure, under the premise of satisfying the rigidity and strength, the weight of the mechanical table body should be as light as possible, and the moment of inertia of each rotating part should be as small as possible. Considering the driving power, the smoothness of the motion and the controllability of the system, the closer the center of gravity of the mechanical table is to the axis of rotation, the better. However, from a safety point of view, the position of the center of gravity of each rotating component should be controlled within a certain range below the rotary axis.
According to the technical parameters and indicators such as the installation table size and bearing requirements of the design task book, combined with the previous design experience, the structural size, section size and thickness of the mechanical platform are initially determined, and the three-dimensional modeling design is completed. The corresponding associated constraints are assembled.
First, determine the position of the center of gravity of each rotating part. If the position of the center of gravity is not suitable, the requirement of the position of the center of gravity can be satisfied by adding a weight in the lower part or changing the size of the structure. Perform finite element calculations on each component to verify that the stress and strain of each component meet the accuracy requirements of the measurement system. If the requirements are not met, the structure of the corresponding part is modified until the requirements are met.
Mechanism motion simulation analysis and interference check
Mechanism motion simulation analysis
The model of the mechanism motion simulation should adopt a bottom-up assembly method to build a three-axis swing double-track mechanical assembly. First insert the completed base so that the three defined planes of the base part coincide with the three defined planes of the assembly, so that the base parts can be completely restrained. Then, the outer ring, the middle ring, and the inner ring are constrained one by one according to the corresponding assembly relationship. As shown in Figure 1, the outer ring and the frame constrain two degrees of freedom, the outer ring can swing around the Y axis; the middle ring and the outer ring also constrain two degrees of freedom, the middle and the outer X axis can swing; the inner ring and the middle ring also constrain two One degree of freedom, the inner Z axis can swing.
For the assembled assembly model, the motion simulation can be performed with Solidworks/Motion. According to the relevant conditions and parameters given in the task book, the different motion states of the product can be simulated, and the motion performance of the product and the correctness of the design calculation result of the product can be verified. .
Figure 2 button logo
Figure 3 settings window
As shown in Figure 2, use the mouse to click the button pointed by the arrow, and the left window shown in Figure 3 will appear. Check if Revolute corresponds to the Y axis (è‰ axis), whether Revolute2 corresponds to the X axis (roll axis), and whether Revolute3 corresponds to the Z axis (pitch axis). Use the mouse to select the "Revolute" button, then right click and select "Properties" to display the right window as shown in Figure 3. In this window you can add the rocking mode, the rocking mathematical model (Harmonic), and the amplitude of each rocking axis. Value, period, angular velocity and angular acceleration parameters. In the Motion drop-down menu, select the "Intellimotion Builder" button, the window shown in Figure 4 appears, in this window you can add the running time and the number of points calculated, generally take 2 to 3 cycles, 500 to 1000 calculation points Just fine. After the added parameters are added, click the shortcut button 2 indicated by the arrow in Figure 2 (and then click the “simulate†button in Figure 4), and then the swing simulation motion can be performed.
Figure 4 Simulation Setup Window
After the end of the operation, use the mouse to select the “Revolute†button, right click, select “Plot†and the window shown in Figure 5 will appear. Click on the “Rotary Motion Generator†button to select the corresponding drive of each rotary axis. Torque. Referring to the coordinate system in Fig. 1, the Y axis is the è‰ rocking axis, the X axis is the roll axis, and the Z axis is the pitch axis. Thereby, a driving torque map of the outer ring (Y axis), the middle ring (X axis), and the inner ring (Z axis) is obtained. As shown in Figure 6.
Figure 5 Selecting the driving torque of each rotating shaft
Figure 6 Driving torque diagram of each rotating shaft
In addition, the effects of motion simulation can be directly output as video files. After selecting the “Export Results†button in the Motion drop-down menu, click the “To AVI Movie†button to store the motion simulation video files in the specified directory.
Interference check of moving parts
Need to say more here, the designer should perform motion interference check on the moving parts of the assembly, check the interference of the limit motion, and check the assembly situation and the accuracy of the component model, so as to find out the interference of the spatial arrangement of the product structure early. Problems such as collisions with sports organizations.
After selecting the "Intellimotion builder" button in the Motion drop-down menu, click the "Interferences" button (as shown in Figure 4), and then click the "Check Interferences" button to perform the motion interference check. If there is motion interference, It will be displayed in the window shown in Figure 7, and then it can be modified in the corresponding part. If there is interference, the specific interference position can be seen, and the corresponding part is modified.
Figure 7 Motion interference tips
Transformation of 2D engineering drawings
After completing component modeling, assembly assembly, finite element analysis, motion simulation, and interference checking, you can transfer to drawing drawing, and quickly and accurately generate the required 2D engineering view through the model. Because the model and the drawing size are related, and the dimension can be automatically generated, which reduces the human error and workload in the design, the designer's main job is to modify the dimensioning, geometrical tolerance, and compile the necessary technical requirements to meet the requirements. China's mechanical drawing standards and corporate standards.
summary
The designed products described in this paper have been delivered for use. Through the loading and running tests of the products, the actual performance and calibration results of the products meet or exceed the requirements of the task book. The three-axis simulation rocking and resurfacing mechanism constructed by Solidworks/Motion software is successfully applied in three-dimensional solid modeling, assembly, three-dimensional mechanism motion simulation, moving component interference inspection process and some techniques.
In the process of new product development, development and design, especially for non-standard equipment such as rocking double-wire devices, it is necessary to calculate and analyze the stress and strain of structural parts. The calculation and structural design work is very large and cumbersome, and the Solidworks/Motion software is used. The simulation design of the product greatly improves the design efficiency, avoids a lot of changes in the design process, and ensures the design quality. Reasonable use of software in hand can not only shorten the development cycle of new products, but also greatly reduce design costs, reduce the risk of new product development, and improve the market competitiveness of enterprises.
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