Installation process of coupling

Time: 2011-03-20 17:42 Author: XINLAN Coupling Click:
Installation process of coupling

     Cold loading
  forCouplingThe fits with corresponding clearances with the shaft can be installed directly after cleaning the mating surface and applying lubricating grease.For the fits that are not very large for transition fit and interference, or fits with special requirements (such as protecting precision components already installed), press-fitting method can be used, but press-fitting equipment is required.Hot assembly of couplings is often used in the installation of heavy equipment such as large motors, compressors and rolling mills, because couplings and shafts in such equipment are usually connected together by interference fit.There are several methods for assembling interference couplings: press-fit assembly, low-temperature cold assembly, and hot-set assembly.The cold shrink assembly method generally uses liquid nitrogen as a cold source and requires a certain insulation container, so it can only be used when conditions permit.
  The essential principle of hot fitting is to heat the containing part (hole) to expand its diameter to a matching interference value, and then install the contained part (shaft). After cooling, the machine will reach the required bonding strength.In fact, the heating expansion value must be larger than the matching interference value to ensure smooth installation and avoid serious accidents of shaft and hole jamming due to the cooling and shrinking of the containing parts during the installation process.At the same time, in order to ensure a greater meshing force-bonding strength, the bonding surface of the thermal suit must be processed, but not excessively smooth, because a certain surface roughness (usually Ra3.2) is not affected by axial movement. After being flattened and cooled, the bonding strength of the internal and external parts will be greater, and the torque that can be transmitted will also be greater.
  Selection of heating method
  The method of heating the containing parts to the required temperature should be selected according to the site conditions, the size, quantity and requirements of the heated parts.The general heating methods include: solid fuel heating, hot dip heating, oxygen-acetylene flame heating, blowtorch heating, electric heating and so on.If conditions permit, it can be heated in special furnaces (such as flame heating furnaces, salt bath furnaces, resistance furnaces and other electric heating furnaces).When the site conditions do not allow, a simple stove can be built, and solid fuels such as wood and coke can be used for heating.If conditions permit, gas or liquid fuel can also be used for combustion.Immersion heating is usually only used for couplings with smaller dimensions (inner diameter below 100mm). The method is simple and the heating is uniform.When the oxygen-acetylene flame heating method is used to heat small parts or parts of larger parts, the method is simple, but requires more skilled technology to prevent overheating and burning of the parts.For large couplings, multiple oxygen-acetylene flame heating and blowtorch heating can also be used in combination, and the effect is very good.Although the electric heating method is a better heating method, its use at the installation site is limited due to the need for special equipment. However, the electric induction heating method can still be considered for selection.The electric induction heating method used on the large and medium-sized couplings at the installation site is to pass the working frequency (50Hz), low voltage and large current through the induction coil.Under the same conditions and the same material, the current frequency f is inversely proportional to the current penetration depth δ.Now it is hoped that δ is large, so instead of intermediate frequency (500~10000Hz) and high frequency (105~106Hz), the working frequency (50Hz) is adopted.Low voltage and high current can increase alternating eddy current and hysteresis loss, and increase heat generation.The commonly used voltages are 380V and 220V.
  In practice, accidents that may often occur are:
  1.CouplingThe axis is skewed and the coupling can’t advance: In order to prevent such accidents, in addition to correcting the axis, the position of the coupling hole and the shaft, and the position of the striker, it is also necessary to pay attention to the position of the impact point. Choose, *, two hits should be light, after entering a certain distance (about 1/3), before you can slam hard.
  2.Other accidents may include: the impact block pulley moves backward due to the improper position, the hoist chain slips down, the fuel is insufficient, the fire alarm, etc., all should be paid attention to in advance and carefully checked during the tool preparation and operation training phase.
  3.When precision parts such as bearings and mechanical seals have been installed on the main shaft in advance, it is forbidden to hit and hit the coupling forcefully to prevent damage or damage to the precision parts.

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