precautions for using bolt stretcher
Precautions for Using bolt stretcher
When you operate the bolt tool, you should know some precautions for using bolt stretcher, it is very important. Bolt stretcher belongs to ultra-high pressure products, it should be used correctly, otherwise it can not achieve the expected effect, and even may be dangerous.
Before using the bolt stretcher, the oil pressure must be calculated to prevent the working pressure from exceeding the bearing capacity of the bolt, causing plastic deformation of the bolt and damaging the bolt. The tensile force produced by the bolt stretcher is equal to the product of the output pressure of the power source and the effective area of the piston. Therefore, the allowable stress can be calculated according to the strength grade of the bolt used, so as to reverse the output pressure of the pump. Ensure that the deformation of the bolt is within the elastic deformation, and complete the work without damaging the bolt.
In the process of pressurization, the pressure should be as uniform as possible. Every time a certain pressure is increased, it shall be increased after the pressure is stabilized to avoid excessive impact tension and affect the pretightening effect of bolts.
During the stretching process of bolt stretcher, pay attention to the maximum design stroke of the stretcher. If the maximum stroke is exceeded, the seal will be cut if it is light, and the safety accident will occur if it is heavy. Generally, the stretcher has a maximum stroke warning line, which requires the user to pay attention to the maximum stroke at any time during the use.
When using the stretcher to remove the bolt, when the stretching nut is tightened, loosen about 3 / 4-1 circle to avoid tightening the stretching nut on the piston when the bolt is elastically reset. When the bolt is pretightened, there is no such problem. This part of the force is mainly borne by the working nut rather than the stretching nut.
In order to reduce the mutual influence between bolts in different steps, the sequence and tensile force of bolts should be reasonably arranged. Generally, the order should be arranged according to the principle of symmetry. For example, when the flange of the 8 bolts is pretensioning with a single stretcher, the tension control of each step is more complicated, and the pretightening bolt must have an effect on the pretightening.
Above are all of description about Precautions for Using Bolt Stretcher.