Cylinder Low-speed Friction Characteristics

Since pneumatic system has the advantage of low cost, low weight-volume ratio, anti-pollution, easy to maintenance and anti-jamming, it has been widely used in many manufacture fields. Recently pneumatic technique has become one of the important means to realize automation. As the development of the semi-conductor, ceramic, glass, and pottery industries, it is necessary for companies to produce a range of standard cylinders to provide very low speeds and smooth stroking. First this thesis deeply researches on the mechanism of stick-slip and all kinds of influences. After that, a platform is developed for investigating the friction. And the data collection and motor controlling software is also designed. Thus the characteristic of friction at low velocities is analyzed.The whole thesis consists of four sections:Chapter one first briefly states the technique feature, the current application situation and the frontiers of pneumatic control techniques, then introduces the developing-history and current application situation of low velocity cylinders. The methods to improve the movement of capability of cylinder are also described. In the end this chapter points out the subjects of main research work.Chapter two introduced the theory of friction by tribology method. Also states the concept, description and harm of stick-slip. Then described the mechanism of stick-slip and all kinds of influences. At last the mathematic model of friction is presented.In chapter three, as the experiment bases of research, a platform was developed for investigating the friction, including the hardware and software parts. There are system of driving, sensing, data collection and juncture in hardware system. And the software part is mainly consisted of A/D and D/A channels for the data in and out. Here used the MATLAB and Visual C++ to design the software.Chapter four states the methods of how to fit data. The methods are polynomial fitting and exponential fitting. Here we can get the expression of friction and velocity of all kinds of cylinders. And the influences of pressure, load, seal and lubrication of friction is validated.