Reasons for the falling off of the tensioner of th

2022-08-01
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The reason why the tensioner of the driving chain of the mixing cylinder of the asphalt regeneration equipment fell off

the tensioner of the driving chain of the mixing cylinder of the main machine suddenly fell off within less than 6h of the trial operation of a Finnish road mix asphalt geothermal reprocessing equipment. After the foreign personnel replaced the tensioner of the same model, the tensioner fell off again after less than 16h of operation, resulting in the jamming of the mixing blade in the mixing cylinder, making the asphalt regeneration impossible

the mixing cylinder is a double shaft horizontal mixing cylinder, and each mixing shaft is driven by an independent hydraulic motor (see the attached figure). The main function of the mixing cylinder is to fully mix the old materials milled by the milling drum in front of the equipment with the added new materials and discharge them out of the cylinder. Since the load on each mixing shaft changes randomly, in order to prevent the mixing blade from getting stuck due to different loads, a drive sprocket is installed on each mixing shaft to balance the load of the two shafts through the drive chain, so as to ensure the synchronous rotation of the two shafts

the original tensioner consists of a spring support and a circular solitary plastic support plate, which is fixed on the spring support by three screws. When we checked the fallen plastic support plate, we found that what should be paid attention to during the operation and storage of the electronic universal testing machine: three fixing screws have been broken, and the threaded hole on the stressed side has obvious deformation. According to the damage of the supporting plate, it can be concluded that the three screws were broken under the action of excessive repeated shear force. Therefore, we checked the tightness of the chain and the installation position of the tensioner according to the layout of the transmission mechanism, and found that the tightness of the chain and the installation position of the tensioner were appropriate, and the lubrication of the chain was good. The analysis shows that the most likely cause of excessive shear force is that the loads on the two mixing shafts are very asymmetric (for example, one side of the mixing blade is stuck), resulting in a sudden load on the transmission chain. This sudden load acts on the back of the tensioner, resulting in a great sliding friction resistance between the chain and the support plate, so that the screw is broken

in order to reduce this sliding friction resistance, the most effective method is to change the sliding friction between the chain and the support plate into rolling friction. Therefore, we made a self-made tensioning wheel and installed it on the bottom plate of the transmission box. It has been used so far and has great utilization value. More experiments require that the tensioner has never fallen off again. (end)

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