What is a good choice for the spindle seal of DTM290-470 low-speed steel ball coal mills?
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At present, the main shaft of this model of coal grinder exhibits a large runout of 0.50 mm. The oil inlet temperature of the main shaft bearings is 44°C; due to the hot weather and high outdoor temperatures, there is no oil leakage at the oil inlet, but the high temperature of the bearings prevents continuous operation. When the opening degree of the oil inlet valve is high (above 50%), oil leakage occurs in the seals of the main shaft bearings. Currently, felt seals are being used; however, given the stringent requirements of the operating environment, I would like to know what type of seal and what material could be used to eliminate this oil leakage problem
An oil baffle can be installed inside the bearing housing to reduce the impact force. Due to the large radial runout and low speed, it is still recommended to use wool felt.
The shaft diameter is 1400 mm – is this suitable?
To solve the problem, it is necessary to identify the root cause; the following suggestions are given: 1. The reason for the abnormal vibration of the ball mill – excessive vibration leads to a poor sealing effect； 2. Oil temperature control: if the oil temperature is too high, its viscosity decreases, preventing the formation of an oil film, which poses a significant risk ； See if a small heat exchange unit can be installed to reduce the temperature. 3. Oil pressure control: the pad is lifted by oil; if the pressure is too high, leakage will occur. This requires trial and error, but it’s important to keep the oil pressure as low as possible while still being able to lift the pad. If the sealing area is large, try using PTFE packing along with a spring compensator; this allows it to move forward on its own when worn out, but it’s necessary to control the amount of movement.
With a shaft diameter of 1400 mm, it is better to use an isolation gas for sealing; this helps to blow the oil back. However, it is advisable to install a vent pipe on the oil tank to allow gases to be discharged promptly.
Also, I’m not sure if this is feasible? The shaft seal gland has been extended, and the excess oil is guided back to the oil return pipe through a pipeline