| As our nation joint into WTO,the auto industry develops in a high speed,at the same time,it improved the manufacture level of the automobile parts.The new type auto engine calls for higher reliability,lower noise and a compact structure.So the silent high reliability chain is used in auto engine more and more widely.But our technology develops too slowly,which result in the restrict in the study and exploitation of the tooth chain. we still have a big distance with the developed country in the variety,specification,performance and quantity of the tooth chain.Many of the automobile and motorcycle company have put forward rigid qualification of test and accept to the shaft center distance and tolerance of the tooth chain. The main reason is that it plays an important role in the transmission steady and noise for the chain shaft center distance. While, in our nation, nothing have been reported about the calculation and testing of the shaft center distance of tooth chain with round pin, at the same time, national standard of the tooth chain also need the theoretical support urgentlyFrom the present condition of our automobile industry, the development trend of spare car parts was analysed, as the tooth chain was dependent upon importation from foreign countries, and we are still in short of decision-making power of intellectual property of the tooth chain. With the support of national nature science foundation, the thesis makes theory study and experiment checking of the shaft center distance of the national tooth chain CL04T-5 and the inner-out meshing tooth chain SCR04-5.One,The theory calculation of the shaft center distance of tooth chainWith the construction of the calculation method the shaft center distance of tooth chain popularly used, such as chain length method,involute function method,Winklhofer method,non-linear equation method, involute function method and chain pitch probability method were chose to calculate the theoretical shaft center distance. Which lays the foundation of the theory.Two,The effect of tooth chain meshing mechanism to the shaft center distanceThe meshing mechanism of the out meshing tooth chain and the inner-out meshing tooth chain were Discussed respectively and the fluctuation of the shaft center distance in different phase was simulated with computer graphic, which have practical guiding role for analyzing the effect caused by fluctuation of shaft center distance to the transmission performance.The result of the experiment shows: the tooth number of wheel should be as bigger as possible, which can weaken the chordal effect. At the same time, the inner-out meshing tooth chain has a smaller fluctuation of the shaft center distance than the out meshing tooth chain.Three,The effect of the part manufacture precision to the shaft center distanceThe aperture center distance,aperture diameter and pin diameter of the out meshing tooth chain CL04T-5 and the inner-out meshing tooth chain SCR04-5 were measured. The calculated result from collected data is a little smaller than the theory result,the reason is that all the parts which didn't undertook pre-stretching or running-in, was taken at random from the storehouse. The manufacture precision satisfies the demand of the design.Four,The pre-stretching and running-in effect on the shaft center distance After pre-stretching and running-in, the pitch increases about 0.03%~0.05%, accordingly, the shaft center distance gains 0.03%~0.05%.Five,The fluctuation of the shaft center distance measured in experimentIn different meshing position, the shaft center distance of the tooth chain was measured in fixed loading force with the shaft center distance measuring instrument LZC-600. From the collected data, it can be concluded that the shaft center distance has the maximum when the center line of the tooth groov perpendicular with the tense side of the chain, So it can be considered the shaft center distance has the largest value in this position. Six,The effect of loading force to the shaft center distanceShaft center distance was measured in different loading force with the shaft center distance measuring instrument LZC-600. By analyzing the collected data, it shows that the haft center distance has a linear relationship with the loading force(as figure 1),when the loading force varys, the result can be corrected with the loading force corrected function.Seven,The design of parts tolerance of the tooth chain Considering the conclusion coming from the theory deduction and experiment, combining with the demand to the tooth chain of the companies parts tolerance of the round pin tooth chain was designed, which satisfies the companes。... |
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