Adopt the clearance fit NTN bearing heating installation and axial positioning method

When NTN bearing ring rotating load, such as using clearance fit, the installation is in the process of the rotation of the bearing of the ring will happen with surface creep phenomenon, easy generation micro wear and tear, at this point with surface will appear the injuries such as burns, cracks, therefore, NTN bearing slewing ring and mechanical parts of the load of the axis or hole with interference fit should be adopted. In the bearing parts of the machinery, NTN bearing should be in the radial, axial and circumferential ( Tangential) The positioning of the fixed three directions have different requirements. In general, imported bearing axial fixation is using axial closed or part with radial tight fit, free side in institutions supporting import bearings are often not be fixed in axial, to compensate for agency system in the axial dimensional change in the process of installation or heat bilges cold shrink. NTN bearing radial and tangential fixed method, usually all by the inner diameter of the bearing and bearing inner hole and shaft diameter. Individual institutions, such as rolling mill bearings, roller conveyer's long axis transmission mechanism with the form such as key to limit the tangent direction of the sliding bearing inner circle. NTN bearing additional sealing device can effectively protect bearings in the outside dirt intrusion under the favorable conditions of work, but this kind of additional sealing device will increase the mechanical mechanism of the axial size, the use of bearing and inconvenient installation, at the same time, the additional sealing performance of the sealing device is often suitable journal and shell parts processing precision and the influence of the shape tolerance, so the structure is compact, and strict sealing parts, such as motor bearing, has been in the use of deep groove ball bearings with seals. NTN bearing in addition to with good sealing performance, can also in the whole process of the functioning of the bearing grease without supplies and keep a good running condition, so as to reduce maintenance costs and working hours. When the NTN bearing inside diameter greater than 70 mm, or cooperate with larger interference, heating method makes the bearing hole expansion, such easy installation to save time and avoid damage caused by the force is too large. It is enough. More than 120 ℃ tempering occur will cause the NTN bearing, the lower hardness and precision of the ring. Commonly used heating method has: 1 electric hot plate bearing heating method be placed on the electric hot plate temperature of 100 ℃ for a few minutes, this method is most convenient, such as reverse it a few times can make the bearing heated evenly, and the efficiency is high, the size of the NTN bearing can use this method. 2 electric furnace heating method to the bearing in the automatic temperature control of the closed electric furnace heating, uniform heating, accurate temperature control, heat fast, suitable for the occasion of a batch of heating a lot of NTN bearing. 3 induction heating method using induction heater can be fast, reliable and clean will be heated to the required temperature, NTN bearing it particularly suitable for the occasion of inner ring tight fit, just because of the heated inner ring, and the outer heat is small, so can be a drag on the shaft, also easily into a hole. 4 bulb heating heating method using 50 w bulb NTN bearing, can guarantee the heating temperature about 100 ℃, the smaller the bearing can be directly on the bulb, larger bearings taper enclosure may be placed on a light bulb, conical cover can prevent heat losses, light bulbs and heated evenly. Conical cover can be adjusted up and down, in a certain heating range that can adapt to different size of bearing. If the far infrared light bulb, pay attention to the light bulb direction should be down, so as to avoid of infrared radiation is bad for the eyes. This bulb can be energy saving. Bulb heating method is suitable for small and often do not need; To the NTN bearing heating, light bulbs still can make lighting at ordinary times, moreover does not need any other equipment. Oil 5 heating method which is widely used in the traditional heating method, the bottom of the tank from 50 to 70 mm in the metal mesh, bearing on the Internet, NTN bearing with a hook to lift. Bearing should not be placed directly on the bottom of the channel, in case of contact with the bottom of the channel bearing parts of the local heat is too high, or dirt into the bearing groove bottom sediment. Oil tank heating method of the key points are as follows, should use no corrosive thermal stability good mineral oil, it is best to transformer oil, oil, and the container should be kept clean. Tank capacity should be heated with the size of the NTN bearing and oil amount, if the container is too small, in continuous operation, one into the bearing oil temperature will drop quickly, the effect is bad. Heating installation method (1) the main points of the heating temperature to control the appropriate, NTN bearing high temperature cause damage, temperature is low enough ring expansion, the effect is not significant. 80 ~ 100 ℃ heating temperature of the thermal expansion of the inner ring diameter, this with the general NTN bearing, the amount of interference is already enough. (2) a reach the required heating temperature, be about to install as soon as possible, so as to avoid cooling and installation difficulties. (3) the NTN bearing during cooling in the width direction also have shrinkage, therefore when installation to a certain pressure inner ring to the shoulder pressure, and with a very thin feeler after cooling test for detection, whether inside the gap between end face and shoulder. All in all, action requires skilled, quick and accurate. In order to prevent the NTN bearing on the shaft and the NTN bearing hole move, bearing inner ring must be tightened on the shaft; The outer ring must tighten the bearing hole ( Or set of glasses) 。 NTN bearing inner and outer ring needs to be a two-way or one-way axial fastening, swimming or axial, depending on the limit requirements of the bearing and the bearing type.