凸轮机构的动态分析与设计研究

发布时间：2018-05-13 21:20

本文选题：动态分析 + 凸轮机构　；参考：《陕西科技大学》2012年硕士论文

【摘要】：凸轮机构学作为机构学中的一个重要分支，凸轮机构的设计与制造目前还处在相当活跃的阶段，还主要体现在凸轮的CAD/CAM和动力学的研究上。首先介绍了一种适用于中、高速凸轮机构的谐波运动规律，该运动规律公式的特点就是它是由多个谐波分量叠加而成，且在一个运动周期内能用一个数学公式来表达。其基本思想是以理想工作要求为参考，采用最小二乘法则来优化位移、速度或是加速度，以此来确定谐波分量的系数；还可以以加速度为优化目标函数，约束条件为某时刻对应的位移、速度、加速度或跃度等，转化为有约束优化问题，借助优化分析软件求得谐波分量的系数，并且结合实例，设计完成了谐波运动规律并在同等条件下与正弦曲线运动规律，修正正弦曲线运动规律进行了特性值图像的对比，从而体现了谐波运动规律在最大速度和最大加速度较小的优点。其次，，课题以机械系统动力学理论为基础，对凸轮机构进行动力学响应分析，包括位移响应、速度响应和加速度响应，根据响应结果的对比分析，能够说明谐波运动规律在降低高速凸轮机构振动的效果是比较明显的。分析步骤依次为建模、建立运动微分方程与求解运动微分方程。运动微分方程只在某些简单情况下可以得到解析解，一般情况下，只能用数值法进行求解。本文中对动力学响应求得解析解，并与理想输出响应进行了对比，说明谐波运动规律被应用于凸轮机构设计的适用性。最后，对凸轮机构进行了模态分析，其主要目的是为改进机构的动态性能以及为优化设计提供客观的参考数据。不同阶模态对应的频率就对应了构件不同的共振频率，构件的共振频率就是设计人员进行机构动态分析时所关注的。论文中通过摆动从动件平面凸轮机构为例，首先按常规的方法完成了机构的设计，在ADAMS中对其进行了动态分析，通过分析体现了常规方法在设计中引起的不足即激发了机构的振动，使从动件运动轨迹失真，于是结合动态分析的模态结果，确定谐波阶数，将谐波运动规律应用于凸轮机构的设计，并再次仿真测量从动件的运动状态，以此体现将谐波运动规律运用于中、高速凸轮设计的优点及适用性。
[Abstract]:As an important branch of cam mechanism, the design and manufacture of cam mechanism is still in a very active stage, which is mainly reflected in the study of CAD/CAM and dynamics of cam. This paper first introduces a kind of harmonic motion law suitable for medium and high speed cam mechanism. The characteristic of the formula is that it is superposed by multiple harmonic components and can be expressed by a mathematical formula in a motion period. The basic idea is to optimize the displacement, velocity or acceleration by using the least square method to determine the coefficient of harmonic component, and to optimize the objective function by using acceleration as the reference of ideal working requirements. The constraint condition is the displacement, velocity, acceleration or jump corresponding at a certain time, which is transformed into a constrained optimization problem. The coefficient of harmonic component is obtained by means of optimization analysis software, and an example is given. The law of harmonic motion is designed and compared with the law of sine curve under the same conditions and the law of modified sine curve is compared with the image of characteristic value. Thus, the harmonic motion law in the maximum velocity and the maximum acceleration of the advantages of small. Secondly, based on the dynamic theory of mechanical system, the dynamic response of cam mechanism is analyzed, including displacement response, velocity response and acceleration response. It can be shown that the harmonic motion law is more effective in reducing the vibration of high speed cam mechanism. The analysis steps are modeling, establishing the motion differential equation and solving the motion differential equation. The analytic solution of the differential equation of motion can be obtained only in some simple cases, but in general, it can only be solved by numerical method. In this paper, the analytical solution of the dynamic response is obtained and compared with the ideal output response. It is shown that the harmonic motion law is applied to the design of the cam mechanism. Finally, the modal analysis of the cam mechanism is carried out, the main purpose of which is to provide objective reference data for improving the dynamic performance of the mechanism and optimizing the design. The frequencies corresponding to different modes correspond to the different resonance frequencies of the components. The resonant frequencies of the components are the focus of the designers in the dynamic analysis of the mechanism. In this paper, the planar cam mechanism with oscillating follower is used as an example. Firstly, the design of the mechanism is completed according to the conventional method, and the dynamic analysis of the mechanism is carried out in ADAMS. Through the analysis, the deficiency caused by the conventional method in the design is shown, that is, the vibration of the mechanism is excited and the track of the follower is distorted, so the harmonic order is determined by combining the modal results of the dynamic analysis. The harmonic motion law is applied to the design of cam mechanism, and the motion state of follower is again measured by simulation, which shows the advantages and applicability of applying harmonic motion law to the design of high speed cam.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH112.2

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