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摘 要
我们知道，偏心类的零件在机械领域中应用的非常广泛，比如在机械传动中，偏心类的零件可以使回转运动转变成往复运动，具体一点，比如我们要研究的课题——双偏心曲柄轴，它不仅可以像一般的轴类零件可以传递自传，还可以传递公转，使一些大型机械不但提高了生产效率，也节省了成本。
在充分了解了偏心轴零件的特点后，通过生产实践，运用我们所学的知识，比如机械制造，机械设计，机械制图等等，发现传统的加工偏心轴的加工方法以及微调三爪，四爪卡盘的方法并不能很好的保证加工结果；首先这几种方法加工困难、效率较低，再者精度也不容易保证，互换性也差。所以针对此种现象，我们就需要一种加工精度高并且高效的加工方法——使用组合专用夹具。
夹具在机械领域中的作用是不可替代的，它不仅可以保证质量，提高生产率，减轻工人劳动强度以及工作安全，因此在设计时需要保证这些功用并且还要注意到夹具结构的合理性与制造夹具时的精密性，为了达到这些目的，我还需要学习定位原理，计算夹具的夹紧力来保证制作夹具的精密性等等。
首先拿一个已经加工好的零件作为设计夹具的零件，将其用CAD软件转化成为图纸，看图纸了解零件的特点，针对其特点制定加工工艺。其次了解夹具相关知识，用所学的知识设计出夹具的大体样子。经过一系列的改进，最后用CAD软件绘出夹具的零件图以及装配图。
关键字：夹具；偏心轴；偏心距；工艺分析；工件定位
ABSTRACT
As we know,the type of Eccentric components is widely applicated in the field of mechanical parts,for example , in the mechanical transmission,the type of Eccentric components can make the rotary motion into reciprocating motion.Specifically,For instance the topic which we will research——Double Eccentric Crank Shaft:It not only can transmit an autobiography like a normal shaft parts,but also can transmit a revolution,so that Make some big machine not only improves the production efficiency,but also save the cost.
After the full understanding of the features of the eccentric shaft parts, through the production practice, using knowledge what we learned , such as Machinery Manufacturing, Mechanical Design, Mechanical Drawing, etc., found that the traditional machining methods of eccentric shaft and fine-tuning three jaw, four jaw chuck method in guarantee processing results is not very good; First of all these methods processing difficulty, low efficiency, also is not easy to ensure accuracy, interchangeability is quite poor. So with this phenomenon, we need a high machining precision and efficient processing method——using combination of the special fixture.
Fixture play an irreplaceable role in the field of machinery, it can not only ensure the quality, increase productivity, reduce labor intensity, but also job security, so we need to make sure that in the design of the function and we should Pay attention to
The rationality of jig structure and precision manufacturing fixture, in order to achieve these goals, I also need to learn more about positioning principle, calculate fixture clamping force to ensure that production fixture precision and so on.
First take a component which have already been processed as design of fixture , make it into the drawings with CAD software, understanding the features of component by wtaching the drawings, according to its characteristics to make machining process. Second learn the related knowledge about the fixture , using knowledge to design the fixture's general appearance. After a series of improvement, and finally using CAD software to draw fixture components drawing and assembly drawing.
Key words: Fixture ；Eccentric shaft； the range of eccentricity ； Process analysis； positioning
目 录
