| The linear-reciprocating motion have already been widely used in various fields for industry, high performance sealing is required between the reciprocating moments and the shell in the chemical industry, biological products, pharmaceutical, food processing, with less friction loss caused by seal. Seal performance will directly affect the performance of the machine, such as the potential for leakage implies that the measurement precision of metering pumps will be reduced, and the accuracy of the transportation of chemical reagents, analysis of fluid and additives will be affected. Leakage can impact on the quality of products and chemical analysis. In addition, the leakage may also cause pollution on the production and the environment, and the loss of friction will reduce the efficiency of refrigeration compressor, affect the dynamic performance of the hydraulic system further.The form of sealed in linear-reciprocating including hydraulic seals, piston rings, pneumatic Seals, and flexible packing seals, and so on.A new sealing system, the pressure balanced shaft seal, with substantial extended limits of capacity is presented. The sealing system has been developed because of the close cooperation between the Institut fuer Maschinenelemente of the University of Stuttgart, Germany and the Merkel Freudenberg Fluidtechnic, Hamburg, Germany.In 1960's, ferrofluid sealing technique is used widely. It has many advantages because there is only sealing between magnetizer and liquid contact in sealed parts.Based on sealing parts of reciprocating motion, the research has been concentrated on two aspects in domestic and overseas. One is to design diversified sealing components of section shape in order to increase grads of oil film pressure between sliding surface and sealing part to control leak and friction using polyurethane or polytetrafluroethylene based on the theory of elastohydrodynamic lubrication. The other is to research ferrofluid sealing.However, we can be faced with some problems in two jobs. Firstly, un-slick surface touch, dynamic lubricate instability and oil boxed up produced by air bubble brought in reciprocating can result in oil film between sealing part and sliding surface became static press oil film so as to leak and large friction. Secondly, reciprocating of parts can arise sealed press film of magnetic fluid distortion and to be taken to edge so as to invalidation of sealing. Otherwise, reciprocating sealing of fluid dynamic press can result in stretch sealing cell crushed, daggle pressure and leak of cold boot and other problems.The sudden invalidation of sealing component and sequent high cost can result in dead disaster. It is critical to deal with poisonous or flow pump of radioactive fluid instead of repair of chemical plant, petrochemical plant and nuclear power plant and high fee of temporary stopped machine. Under the occasions of poisonous element emitted, the invalidation of sealing directly scared human's healthy and life.So research on reciprocating theory and technique of reliable seal capability is very necessary.Magnetic drive is the theory based on modern magnetism and a new technique of realizing force and torsion or power transformation without touch using permanent magnetic material or magnetic force produced by electromagnetism. The equipment of realizing the technique is called magnetic drive.The essential difference of magnetic drive and mechanical drive lies in work clearance using magnetic field through magnetic circle, transferred force by thin wall of isolated set and torsion. For example, magnetic driver pump and stirred bed reactor cancelled off traditional mechanical driver pump after adapting magnetic drive sealing. Dynamic seal touched equipment Axial adapted of bed became static so as to eliminate leak produced by sealing place of transferring axis radically and settle run, emit, drop, leak lying in pump and bed and mechanical heat and friction and other problems. It provided good conditions for diversity costly medium in order to safe and reliable transformation and avoid toxicity produced by stirred reaction, flammability, explosion and corruption.Magnetic drive use torsional moment more than axial force. The paper uses magnetic drive to produce axial force and transfer linear-reciprocating such as soft link in order to realize screen seal of linear-reciprocating.We research and manufacture tow mechanical structures with magnetic field using the characteristic of which magnetic force can span spatial distance working based on the theory of equivalent magnetic nucleus and adapt high capability rare earth permanent material for reciprocating transfer. We use paramagnetism material to separate the two mechanical structures. Because paramagnetism material doesn't impact on magnetic field, magnetic line can cross magnetic field of paramagnetism material and the other mechanical structure to work out and produce magnetic force moving and tracking and realize to transfer reciprocating force between two parts without touch when one mechanical structure is reciprocating. So we can use paramagnetism material between two floating mechanical structure to build structure such as pump shell or jar and seal driven machine completely in order to realize screen sealing of driven machine. There are two methods for analysis and calculating magnetic force which are the view of molecule current and equivalent magnetic charge. Now the theory of equivalent magnetic charge to calculate magnetic is usually used. The paper used it to research and build mathematical model.We design and manufacture magnetic drive and realize the core of linear-reciprocating which is to build the relationship of axial force transferred, intension of magnetic field and parameters.The paper research the contents as following on the basis of reading a lot of related references in domestic and overseas according to the development of magnetic drive and application condition:1. We research and build mathematical model of linear-reciprocating system of transferring magnetic using the characteristic of which magnetic force can span spatial distance working based on the theory of equivalent magnetic nucleus and define the relationship of geometry parameters of magnetic circuitry, magnetic material capability and axial force transferred by magnetic field.2. We build dynamic model of linear-reciprocating system of transferring magnetic based on the theory of Lagrange equation.3. We design and manufacture a magnetic drive of axial linear-reciprocating and experiment flat using rare earth material.4. We measured axial force transferred by magnetic drive on experiment flat and tested correctness of mathematics model of linear-reciprocating. We analysis geometry parameters of magnetic drive and capability target of permanent magnetic material impacting on axial force transferred.5. Based on experiment measurement, we analysis dynamic work capability of magnetic drive and according sensitivity. It can supply theory for choosing parameters of magnetic loop in practice. The theory and experiment shows in the paper that coaxial magnetic drive researched can realize sealing screen linear-reciprocating. It is the most important to settle the problem of sealing linear-reciprocating and improve work capability of linear-reciprocating. |
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