Jaw crusher hydraulic cylinder piston rod frequent fracture solution
Date：2019-10-21 09:31 Source：cementepcViews:
Jaw crusher is an important coarse breaking equipment in cement, mining, metallurgy and other industries.Jaw crusher mainly has eccentric shaft, belt wheel, frame, flywheel and reset spring, bracket, fixed jaw plate and movable jaw plate and other important parts.The working environment is bad and various faults often occur during the operation. In order to ensure the stable operation of the equipment and improve the performance of the equipment, it is very important to do a good job in daily maintenance.Piston rod fracture occurs in the process of jaw breaking. Through the analysis of the causes of this problem, The solution of frequent fracture of piston rod of hydraulic cylinder of jaw crusher is presented.
1. Analysis of existing problems and causes
The main function of this hydraulic cylinder is to connect the moving jaw and the frame, so as to ensure the contact between the bracket and the moving jaw and the frame during the operation of the jaw crusher, and control the backstroke position of the moving jaw to prevent the dropping of the bracket.
When the piston rod is hinged at both ends of the hydraulic cylinder, the diameter of the piston rod is 63mm and the working pressure is 13 ~ 16MPa, the actual tensile stress of the piston rod of this type of hydraulic cylinder is less than the allowable tensile stress, which indicates that there is no problem in the selection of materials, piston rod diameter and other aspects in the design.Combined with the analysis of the phenomenon of the fracture end face on site, the fracture face is neat and there is no shrinkage along the axial section, which also indicates that the main cause of the piston rod fracture is not caused by tensile stress.
The next step is to verify the existence of design defects from the structural aspect.Observation shows that the two faults are almost the same.The piston rod and earring were originally designed to be structurally separated, and the two parts were connected with a threaded structure.The thread size is M56 and the piston rod diameter is 63mm. The thread is located at one end of the piston rod.At the joint of the round rod and thread, there is a section step, and the diameter is reduced from 63mm to 56mm.This point is extremely close to the movable jaw hinge, which is a dangerous point where all kinds of stresses cross converge.
At the same time, the original design to increase the wear resistance of the hydraulic cylinder, technical requirements only on the piston rod hardness requirements, and the strength of no provisions, resulting in the piston rod hardness increased, the corresponding strength may be affected, so that the piston rod brittleness increases, can not resist shear stress and other aspects of interference.These two factors lead to the use of the piston rod in this part of the fracture.
2. Structure improvement of jaw crusher
(1) improved the design concept, forged piston rod and earring into one, combined with a large round corner transition, cancel the screw connection, reduce the stress concentration.
(2) increase the diameter of piston rod to increase the resistance to comprehensive stress.
(3) at the same time, change the heat treatment requirements, increase the strength requirements, so that the piston rod hardness and strength to achieve consistency.
3. Improved effect
By improving the structure of piston rod fracture, the performance is stable, the hydraulic cylinder has no problems within one year after the transformation, and the production efficiency has been improved.
We also need to overhaul the improved jaw crusher according to the requirements. Minor repairs shall be made within half a month to a month according to the overall operation of the machine. Minor repairs shall be made once a year according to the overall wear of the machine.Good maintenance work to ensure the normal operation of equipment.