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Using CosmosWorks to optimize the design of grinder center frame

Abstract: This paper introduces the establishment of a knowledge-based three-dimensional design library of roller grinder center frame based on SolidWorks and parameterization technology, so as to realize the automatic serialization design of roller grinder center frame and simplify the design process. The fully integrated CosmosWorks finite element analysis software is used to optimize the key parameters of the center frame and improve the product quality. And put forward the outlook for the later work

key words: knowledge reuse and optimization of roll grinder center frame SolidWorks cosmoworks

1. Virtual design of roll grinder center frame

with the development of steel rolling industry, there are more and more types and specifications of rolls. The specifications and varieties of the roll grinder for finishing the roll are also increased accordingly. (the roll weight is large, up to dozens of tons. In order to improve the processing quality, the center frame commonly used on the roll grinder supports the workpiece.) There are many kinds of center frames. Although the structure is similar, the design workload is very large. Simplifying the design process and optimizing the design are the problems that designers are eager to solve

we take SolidWorks as the platform and parameterization technology as the basis to establish a unified three-dimensional model library for various central frames of different specifications, which simplifies the design process. On this basis, combined with CosmosWorks finite element analysis component integrated with Solidworks software, some key data of the center frame are optimized, so as to improve the bearing capacity of the center frame, which is expected to significantly improve the processing quality of rolls

the modeling system based on parametric technology is essentially a size driving system. The driving dimensions of this dimension driving system can only be a few, so it is necessary to correlate and simplify other dimensions except the driving dimensions. We use the angle between the horizontal support axis and the horizontal direction, and the angle between the vertical support axis and the vertical direction as the driving dimensions for modeling, while for other dimensions, we refer to the principle of optimal rigidity for corresponding correlation

Figure 1 center frame for worktable mobile roller grinder Figure 2 center frame for grinding wheel frame mobile roller grinder

2. Development of product database based on knowledge reuse

using the powerful configuration function of SolidWorks and parametric design based on product model, a set of models can be used to realize the design of products with different specifications. Because the series part design table and configuration in SolidWorks software are mapped to each other, the product specification can be further expanded by modifying the series part design table to meet the needs of users. Thus, the multi type and multi-level knowledge expression model of product design integrated in the design object is established, and the knowledge reuse of product design is achieved

the design system based on knowledge reuse is called design reuse. Its principle is to realize the reuse of design scheme, design process and design knowledge more effectively through the expression and organization of different levels of knowledge. Design reuse can effectively shorten the design cycle and improve the design quality, so as to achieve rapid response design and manufacturing

3. Establishment of system dynamic model

mechanical research has two ways: prototype and model. The prototype research can fully reflect the actual situation, but it is difficult to fully meet the experimental requirements due to the limitations of field conditions and the influence of various factors. The object established according to the similarity principle and used to collect system information is called system model, which can be divided into physical model and abstract model according to its nature. Physical models are physical models, while abstract models are described by mathematical principles with similar functions and mathematical forms, which are collectively referred to as mathematical modular contraction mechanism cold type. Using computer three-dimensional model can not only be used as the virtual model of prototype, but also establish a virtual model combining physical model and abstract model

the quality of system dynamic model directly affects the results of analysis. The key of establishing dynamic analysis model is "reasonable simplification". First of all, the prototype should be simplified. The powerful calculation and analysis ability of the computer can't deal with the analysis of hundreds or tens of millions of nodes, elements and degrees of freedom of complex shaped parts and assemblies. Therefore, it is unrealistic and unnecessary to use the prototype for finite element analysis, and it is necessary to simplify the model

however, simplification is also limited, so "reasonable" simplification is required. What is reasonable? Most traditional methods use the principle of similarity to simplify, but for parts with relatively complex shapes, especially assemblies, it is difficult to establish a simplified model that can "justify itself"

modal analysis provides a better method for us to establish a reasonable and appropriate model. The model used for modal analysis is modified from Solidworks solid 3D model. The so-called modification is formed by removing some secondary features such as holes and fillets. As for whether the simplified model has similar dynamic characteristics with the prototype, it can be verified by modal analysis and comparison of the prototype and model. Because modal analysis, especially the low-order mode, has a great impact on the dynamic characteristics of the system, by comparing the low-order mode of the model with the low-order mode of the prototype, generally the difference between the two is no more than 3%, it should be considered that simplification is reasonable. The base vibration frequency of our three-dimensional solid model is 710.89hz (Fig. 3), while the base vibration frequency of the simplified finite element analysis model is 729.37hz (Fig. 4), with a difference of 2.6%. Therefore, it can be considered that the simplification is successful

Figure 3 basic vibration frequency of parts Figure 4 basic vibration frequency of simplified model

4. Optimization design based on cosmoworks

optimization design must first determine the optimization goal. The optimization objectives of general parts can be the lightest weight, the smallest deformation and distortion of parts after being stressed, and so on. For the center frame of roll grinder, our optimization goal is to optimize the rigidity of the model

from the point of view of dynamic design, it is not enough to measure the optimal rigidity only by static stiffness, but also need to adopt the analysis of dynamic stiffness for the model. The modal analysis of the model can be realized by using the frequency analysis function of cosmoworks. Through modal analysis, it is easy to find the places and forms of deformation in the part mechanism in time, so as to take corresponding measures

since the main excitation source of the grinder is the vibration caused by the high-speed rotation of the grinding wheel, the speed of the grinding wheel is 3000 r/min, equivalent to 50Hz. Therefore, the farther the base vibration frequency of the center frame is from the excitation frequency, the higher the dynamic stiffness of the system. Therefore, improving the base vibration frequency of the system can be one of the optimization objectives

CosmosWorks, which is seamlessly integrated with Solidworks, is used to optimize the system. We adopt the following methods:

⑴ the highest static stiffness

using the static stress analysis of CosmosWorks, we compare the displacement after loading of the center frame model of various configurations (the included angle between the horizontal bracket and the horizontal direction, and the included angle between the vertical bracket and the vertical direction are two variables). The optimization goal is to minimize the displacement

as shown in Figure 5, the displacement of the workpiece at the contact with the horizontal and vertical supporting heads is different. Due to the corresponding relationship of deformation, the displacement of the horizontal and vertical supporting heads of the center frame is also different, thus increasing the cylindricity error of the workpiece. By comparison, the deformation difference between the two supporting heads of the center frame in Figure 6 is small, and the design is relatively reasonable

Figure 5 h1v25 central frame loading deformation Figure 6 h15v25 central frame loading deformation figure

due to the structural relationship, the development trend of the deformation of the two supporting heads may be different. As shown in Figure 7. H20v20 (the included angle between the near horizontal bracket and the horizontal direction is 20 °; the included angle between the near vertical bracket and the vertical direction is 20 °; the following analogy) the displacement of the vertical bracket is small when the center frame is loaded; While the displacement of the horizontal supporting head is small when the central frame of h20v15 is loaded. The displacement of these two supporting heads will affect the machining quality of the workpiece. In this way, it is difficult to determine whether h20v20 or h20v15 is the final choice for the optimization result

⑵ modal analysis

each component has its specific vibration frequency, which is called resonance frequency. This frequency is determined by the unique vibration form of the component. Once excited by the resonant frequency, the component vibrates in a certain form, which is called modal vibration

frequency analysis can be considered as the simplest form of dynamic analysis. We analyze the dynamic performance of components by studying the free vibration in the absence of damping and exciting force

we use the frequency analysis function of CosmosWorks to study the 64 type grinding wheel frame and the mobile center frame. Through the frequency analysis of the center frame models with various configurations, it is measured that the base vibration frequency of the v5h5 center frame model is 247.85hz, while the base vibration frequency of the h18v25 center frame is 319.98hz. Obviously, the h18v25 center frame model, which has a large angle between the bracket and the horizontal and vertical directions, has high dynamic stiffness and stable operation. At the same time, through the analysis, we also know that for the base vibration frequency, the excitation form is left-right shaking, so we can improve the stiffness by stiffened plates at appropriate places

figure 8 h18v25 center frame model figure 9 v5h5 center frame model

⑶ automatic optimization

the above optimization of the center frame can actually be seen as an enumeration method to compare different configurations to achieve the optimal choice. The result is discrete, that is, even if you know that the optimization value of a certain angle is between 20 ° and 30 °, you don't know how many degrees it is. More importantly, it is multivariable optimization. Therefore, when other angles change, the original optimization value may not be the optimization value anymore

cosmosworks provides an easy-to-use process for multivariable optimization. We use the optimization of the assembly, first carry out static stress analysis and let them deal with it? Answer: 1. Generally, handle it by yourself to get the displacement of the system under the specified load, and then analyze the frequency of the assembly to calculate its base vibration frequency. On this basis, the optimization design is carried out, and the minimum displacement is selected as the optimization objective, while the increase of the base vibration frequency is taken as the constraint. The included angle between the horizontal support head and the horizontal direction and the included angle between the vertical support head and the vertical direction are used as two design variables to analyze and calculate the whole system. Because the whole model adopts parametric modeling, the selection of the upper and lower limits of these two angles is very important. Improper selection may lead to failure of model reconstruction and optimization. After eight iterations, the result of this optimization study converges and a satisfactory result is obtained, as shown in Figure 8. The final optimization result is h13.53v24.67 (Figure 9), which is very close to the result of the relative optimal value h20v25 obtained by using the multi configuration enumeration method. The optimization is successful

Figure 10 optimization design and process of center frame figure 11 final design value

5. Summary

through the optimization design of center frame of roll grinder, we tried to use CosmosWorks software to optimize the design, and the result is satisfactory. Compared with the optimization method of mathematical optimization method, both modeling and calculation should be convenient and intuitive. Compared with the establishment and improvement of the comprehensive evaluation criteria and industry standards of plastic granulator equipment, the finite element analysis module of his three-dimensional design software is used to optimize the design. Cad/cae is more comprehensive, which is a progress. It is a practical choice for production

it is said that solidworks2008 and cosmosworks2008, which will be launched soon, have more powerful analysis functions. Friends in need can contact the experimental machine factory to carry out system action