数控磨床磨削凸轮轴类零件的数学模型与试验研究

【作者】 肖真健；

【导师】 周志雄；

【作者基本信息】 湖南大学 ， 机械制造及其自动化， 2001， 硕士

【摘要】 凸轮轴是汽车、摩托车、内燃机、柴油发动机的关键零件，随着汽车工业、内燃机工业的迅速发展，需求量越来越大，加工精度要求越来越高，凸轮轴的加工工艺、设备也越来越受到人们的普遍关注。我国大多数厂家还是采用传统的机械靠模仿型法磨削凸轮轴零件，这种方法因对不同零件须重新制作不同的靠模，因而生产周期长；又因为零件形状取决于靠模形状，而靠模又容易磨损，故精度难以保证。而国际上比较先进的方法是采用无靠模数控技术，它可以方便地磨削各种复杂形状的凸轮，不必费时费力地制造靠模，大大缩短了新产品开发周期，提高了零件加工精度，减轻了工人劳动强度，有显著的社会和经济效益。 用无靠模数控方法磨削凸轮零件，首要的问题是建立砂轮中心位移的数学模型。本文经过分析、证明，建立了这一模型，并对滚子挺杆、刀口挺杆、平面挺杆等不同从动件情形用一个参数化公式统一表示。 磨削凸轮零件时，由于凸轮形状的特殊性，若零件匀角速度旋转，则凸轮轮廓面各磨削点线速度、磨削力等都不一样，相差可达几倍甚至几十倍，这将严重影响磨削质量，如产生波纹、烧伤和形状误差等。为了消除以上弊端，我们设想找出凸轮各磨削点移动速度规律，使凸轮作恒线速磨削。本文建立了这一数学模型，并通过实验对速度曲线作了改进，磨削效果良好。 另外，对影响磨削效果的其他因素，如磨削力、砂轮半径等，本文也进行了探讨。更多还原

【Abstract】 Camshaft is a key part of automobile, motorcycle and gas engine. With the rapid development of industry, camshaft parts are in great demand, and their precision are higher and higher required. Thus, camshaft process and machine need to pay more and more attention. The traditional method of grinding cam is using copying cam, which has many disadvantages. First, different copying cams have to be machined when grinding different cams parts, which takes a long time. Second, because the part’s shape depends on the copying cam, which is easy to wear out, the precision is difficult to be guaranteed. If we use computer numerical control technology, the copying cam is unnecessary. l’hus, the producing period is shorted, the workers’ labor is lighted, and the precision of parts is improved.Primarily, the mathematical model of the center movement of grinding wheel iieeds to he built while using computer numerical control technology. Based on analysis and experimentation, the formulae for different cases, such as roller tappet, cutter tappet and planar tappet, are advanced.If rotating in a constant speed when cam part is ground by numerical control grinder, the speed and grinding force of different point are different because of the cam’s particular shape, which may cause shape error, and damage the surface quality of the cam. In order to avoid those disadvantages, we assume that the cam part rotates in different rates to make the speeds of every grinding point equal. This paper builds the mathematical model, and optimizes the speed data based on experiment. The cam after being ground has a good quality.In addition, some other factors affecting the quality of cam, such as grinding force and grinding wheel radius, are discussed.更多还原