NTN railway bearing heating assembly time considerations

NTN bearing one of the most common method of replacement has two kinds: one kind is with acetylene oxygen for railway bearing directly heating; The other is for small bearings used in oil heating, thermal, expand the bearing inner diameter, so that assembly. These methods in the long term has been widely used in equipment maintenance, basic meet and solve the problem of the bearing assembly in equipment maintenance. But these two methods to ensure the bearing in the process of heating temperature of heating surface is uniform, it is difficult to determine. Because traditional acetylene oxygen heating is a single burner gas, and heating process only by experience, by heating the railway bearing temperature to the right it is difficult to grasp how many degrees. Temperature is too high, can produce annealing of NTN bearing, the mechanical properties of the low bearing; Temperature is too low, the thermal expansion values is not enough, difficult to assemble. In equipment repair, mechanic, sometimes because of inadequate bearing heating, bearing less than on the correct position, have forced to take down heavy, thus increasing the intensity of labor. To this end, we put forward a kind of changing traditional bearing. 1. Electricity heating replace acetylene oxygen heating. Will become a cylindrical furnace, electric furnace design in his plane named bearing electric heater, depending on the different railway bearing inner diameter can be designed into different power and specifications of the bearing electric heater ( Best suitable scope in NTN bearing inside diameter phi 300 mm/above) 。 The heating device has the following advantages: uniformity and stability of thermal radiation, by heating the bearing surface dust, clean, clean, easy to measure and control the bearing temperature. 2. Using infrared thermometer for temperature monitoring by heating NTN bearing surfaces. Bearing controlling the heating value of general assembly in 100 ℃ ~ 120 ℃ advisable. Within this temperature, thermal expansion value maximum bearing steel, is advantageous for the bearing assembly, the temperature will not change the bearing mechanical properties, and high reliability. Imported bearing heating temperature to bearing size, the required amount of interference for reference. Hot charging work related matters needing attention are as follows: ( a) Not bearing heated to above 120 ℃; ( b) No direct contact with the bottom of the tank for the NTN bearing, best put railway bearing on the metal mesh, or bearing hung; ( c) Bearing heated to higher than the required temperature 20 ℃ to 30 ℃, so that will not happen in inner ring cooling operation, difficult to install; ( d) After installation, bearing cooling, width contraction, so use shaft nut, or other appropriate method, fastening, in case of gap between inner ring and bearing retaining shoulder. Imported bearing temperature check general appearance supposedly from housing. But using the oil hole, direct measurement of bearing outer ring temperature, more accurate. NTN bearing temperature began to rise, without exception, usually stable after 1 ~ 2 hours. If because of railway bearing or as well as the installation, bearing temperature will rise sharply, abnormal high temperature. The reason such as lubricant, bearing clearance is too small, too much bad installation, excessive friction sealing device, etc. High-speed rotation, the selection of railway bearing lubrication method error, etc. Also is the reason.