ABSTRACT: When continuous concrete mixer works, concrete may infiltrate into the sealing device at the shaft end, aggravate the friction of the sealing face and accelerate the failure of sealing. The mechanical analysis of floating seal ring and hub of continuous concrete mixer is carried out. The contact pressure of floating seal ring subjected to O-ring and the average pressure of sealing medium are optimized. The optimum value is calculated to ensure that the contact pressure of the end face of floating seal ring is kept in the optimum range.

Continuous concrete mixer is a machine which mixes cement, sand, stone and water in a certain proportion and mixes them into concrete mixtures. It has the characteristics of fast and uniform mixing, high efficiency, large output, low failure rate and long service life. When working, concrete may extrude the shell from the crevice, and once the solid particles such as sand in concrete enter the relative rotating components, they will produce abrasive effect in the components and accelerate the wear of the components. If concrete enters the lubricating oil duct, it will harden in the oil duct partially, accelerate the wear of components and eventually lead to concrete leakage at the axle end. If the concrete breaks through the seal of the supporting bearing components and enters and destroys the bearing, the whole machine will not work properly. It can be seen that the sealing effect of the shaft end is an important index affecting the performance of continuous concrete mixer. In this paper, the mechanical analysis of floating seal ring and hub is carried out, and the contact pressure of floating seal ring subjected to O-ring and the average pressure of sealing medium are optimized. Shaft end seals from the previous ordinary seal ring seal, to the present seal ring, labyrinth seal, floating seal combination seal, can fully meet the actual needs of the present.

structural analysis

The sealing structure of the axle end of the continuous concrete mixer as shown in Fig. 1 shows that the rubber sealing ring is attached to the flange and the hub under the pressure of the screw, so that the concrete can not directly contact with the oil, which is conducive to maintaining the pressure in the sealing chamber and minimizing the oil infiltration into the concrete, thus adversely affecting the quality of the concrete. The O-ring on the hub also prevents concrete from infiltrating into the floating seal ring. When working, the two O-rings are pressed on the hub and sliding hub respectively under the action of pressure. Under the frictional force of O-ring, one floating seal ring rotates with the hub and the other is stationary with the hub. The common pressure of O-ring and sealing medium produces appropriate compression force on the contact end face of the moving ring and the static ring, which makes the two ends close together, and the very thin liquid film between the end faces achieves the sealing effect. At the same time, the hub, O-ring, floating sealing ring and sliding hub form S-type sealing chamber, which increases the length of labyrinth and makes clearance seal easier to form. Then oil is continuously injected into the closed space at an appropriate speed through the oil passage of the sliding hub with a lubricating pump, so that the closed space always keeps a certain pressure and effectively prevents the formation of clearance seal. Concrete seeps into the floating seal ring. The sliding hub, sleeve, skeleton oil seal and skeleton oil seal flange also form a sealed space, which keeps a certain pressure while working to prevent external debris from entering the floating seal ring. The axle sleeve is used to facilitate the disassembly of the whole device during installation and maintenance.

conclusion

O-ring on hub and floating seal ring prevents concrete from infiltrating into floating seal ring; pressurized sealing medium, floating seal ring and O-ring in sealing oil passage prevent concrete from invading oil passage; skeleton oil seal prevents external debris from invading and damaging floating seal ring. These seals jointly realize the shaft end seal of concrete mixer. The compression of O-ring at floating seal ring and the average pressure of sealing medium in sealing oil passage are important parameters of sealing device, which play a key role in sealing effect. The optimum values of O-ring at floating seal ring are calculated by optimum design method to ensure that the contact pressure at the end of floating seal ring is kept in the optimum range of 0.4-0.7 MPa. Inside.