| Face seal is a kind of radial face seal. It is also called mechanical face seal, mechanical seal for short. It is one of the main types of seal for sealing rotating axis in liquid machine. It is mainly used for axial seal. Compared to the soft wadding seal, the face seal has some advantages, such as low leakage, low friction, long longevity, stable running and simple maintenance. So this kind of face seal is widely used in modern industry.Power chuck belongs to self-centering chuck. Connected with different power equipment (gas cylinder, hydraulic cylinder or electromotor), gas power chuck, hydraulic power chuck or electricity power chuck can be made up. The gas cylinder or hydraulic cylinder is installed at the back-end of principal axis of computer numerical control (CNC) machine as power source. Pulling pole or pipe is connected with rod of cylinder through the hole of the principle axis to pull or push the cuneiform set, which is installed in the chuck at the front-end of principle axis. The axial forward and backward action of the cuneiform set drives the radial movement of the three claws synchronously. This kind of power chuck works quickly and the displacement of claws is small. So it is suitable for volume-production. According to the national requirement, the hydraulic power chuck with rotating speed exceeding 6000 rpm needs to be imported from overseas. One of the main reasons is that there is no technology to produce hollow rotating hydraulic cylinder to mate the hydraulic power chuck. The seal between the rotating component and the fixed component restricts the development of this technology. Whereas the seal working under the condition of high slipping speed, high boundary pressure difference and high temperature, commonly used contact mechanical face seal can not satisfy the high pV value. So none-contact fleet spiral groove and deep circular groove oil film face mechanical seals should be adopted at this position.Power chuck take up prodigious market in west developed country. Although manual chuck occupies some certain market, but the demand for it declines ceaselessly. Power chuck is widely adopted in CNC machine by overseas country, especially in Europe. The installment of power chuck on common machine is continually increasing. At the middle stage of 80 years last century, duing to the restrict of manufacture condition, our country can only produce one kind of short column, low speed, low precision chuck. To meet the high development speed of national CNC technology, high speed wedge power chuck and high speed rotating hydraulic cylinder are required to mate together on the CNC machine. The rotating hydraulic cylinder is the power source of power chuck. Currently the detailed report and research on high speed rotating hydraulic cylinder can not be found nationally and internationally. Amount of research and experiment of high speed rotating hydraulic cylinder have been carried out.Firstly, after synthesizing a lot of relevant literatures and reference home and board, the author summarizes the research and applications of oil film face seal, flowing properies of fluid with variable viscosity and hydraulic power chuck, point out the great significance of the research and put forward the technology difficulties and the key technologies, above the question, main research matters have been confirmed.Under the two conditions of not taking account of the variety and taking account of the variety of viscosity, the formula of pressure distribution and frictional torque is got. Thereby the openning force can be achieved. And the power loss can be calculated. Also under the two conditions of not taking account of the variety and taking account of the variety of viscosity, the leakage properties and frictional loss in the plane oil film face seal gap is contrastively analyzed. So the sealing gap is optimized through the least power loss principle. This theory establishes strong foundation for the structure design and manufacture of rotating hydraulic cylinder. The working principle and the structure shape of deep circular groove oil film face seal is put forward. Under the two conditions of not taking account of the variety and taking account of the variety of viscosity, the pressure distribution of fluid in the deep circular groove oil film face seal gap is contrastively analyzed. So the dynamic flowing characteristics of fluid in this kind of seal gap are achieved. This theory establishes strong foundation for the structure design and manufacture of rotating hydraulic cylinder. When the number of grooves reaches 6 or more, the influence of rotating speed on leakage becomes unobvious. Further more, as the increasing of the rotating speed, the leakage of the seal decreases. This is accord with the upstream pumping theory. Supposing the viscosity is variable, the number of groove is 6, the thickness of the un-grooved zone is not changed, the rotating speed varies among 1000~10000rpm, when the thickness of the grooved zone reaches 1mm, the influence on frictional torque becomes unobvious.Under the two conditions of not taking account of the variety and taking account of the variety of viscosity, the pressure distribution of fluid in the fleet circular groove oil film face seal gap is contrastively analyzed. So the dynamic flowing characteristics of the fluid in this kind of seal gap are achieved. This theory establishes strong foundation for the structure design and manufacture of rotating hydraulic cylinder. When the number of grooves reaches 6 or more, the influence of rotating speed on leakage becomes unobvious. Further more, as the increasing of the rotating speed, the leakage of the seal decreases. This is accord with the upstream pumping theory. Supposing the viscosity is variable, the number of groove is 6, the thickness of the un-grooved zone is not changed, the rotating speed varies among 1000~10000rpm, when the thickness of the grooved zone reaches 0.05mm, the influence on frictional torque becomes unobvious.Simulation research, especially numerical simulation research is one of the mainly used methods in modern industry. It is widely adopted cling to its low cost and saving time. The modes of rotating component are simulated using the ANSYS software, which establishes strong foundation for the structure design and manufacture of rotating hydraulic cylinder. The flowing characteristics of the fluid in the plane, deep circular groove, and fleet circular groove oil film face seal gap are simulated using ADINA software to confirm the correct of theoretical analysis.After manufacturing the rotating hydraulic cylinder, experimental research on specimen have been done, results indicated that the theoretical analysis of the flowing properties of the fluid in the plane, deep circular groove, fleet circular groove oil film face seal gap are correct. Application of these three kinds of sealing technologies makes the rotating hydraulic cylinder satisfying the requirement of high speed power chuck. |
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