Environment Variable Temperature Static Cylinder - Studied Dynamic Friction Low Value Of The Test

With the rapid development of the pneumatic technology, cylinders are widely used as the common pneumatic actuators. The uncertainty of the friction between cylinder piston and metal sleeve is considered as one of the important factors that have effects on its performance. Researching on the friction characteristic, establishing the friction model under different velocity, and then taking effective measures contrapuntally play an important role on the motion function of the cylinders.Formerly the research objects about the friction are rubber seal cylinders. In this project, the new metal seal pneumatic cylinders are showed. A new topic is put forward to the measurement of the micro-friction cylinder. The main contents of the research are summarized as follow:(1) According to the low friction character of the objects, two measuring systems are designed and built. The two methods are indirect measurement that the cylinder was driven by the air pressure and direct measurement that the cylinder was driven by the linear motion actuator. By the experiment, it shows that with the direct measurement, the higher accuracy and consistency of the data are obtained, and this method can preinstall velocity. So the direct method is more applicable to measure low value friction.(2) On the basis of the above mentioned, the static friction and the kinetic friction under different velocity are obtained by the direct measurement. The results show that the friction of the metal seal cylinders is significantly less than the common rubber seal cylinders, and its magnitude is around 1/10 to 1/5 of the rubber seal. As the speed increases, the dynamic friction increases rapidly, first the friction and the velocity exhibited a polynomial multiple relationship. As to a certain extent, relationship between the friction and speed increased linearly. Besides that, both the static and the dynamic friction increase owing to the increase of the bore.(3) In view of the phenomenon that the friction of the rubber seal cylinders changes significantly under different temperature and the metal is more sensitive to temperature, the friction values of the metal seal cylinders may change working in the variable temperature environment. Therefore, in the project we plan to measure the friction of the cylinders under different temperature conditions (0℃～50℃) by experiment and expect to find out the trends and patterns of the changes. A cooled-heated thermostat which have the virtue of no vibration is made to achieve the 0℃to 50℃temperature condition.(4) Using this thermostat system for the friction measurement experiments, the experimental results indicate that the static friction and the dynamic friction are affected by the temperature somehow. The friction of some tested metal seal cylinders basically appears the decrease trend as the temperature increase.