Repair of QY8 crane boom telescopic hydraulic cylinder
It is composed of a constant power variable pump relief valve control box hydraulic cylinder produced by maintenance. According to the structural principle analysis, the main cause of the failure may be 1 hydraulic pump; 13. Relief valve. Control valve; 1. Hydraulic cylinder. Test Analysis According to the situation provided by the user, it is first necessary to determine whether the hydraulic pump is faulty. To this end, the portable hydraulic tester is connected to the pump's output tubing and the relief valve by a straight-through connection to test its flow. When the system pressure reaches 123 and cannot continue to rise, the measured output flow of the pump is still 120. Therefore, there is still room for the pump pressure to rise, so the pressure regulating handle on the right-handed tester is slowly increased, so that the pressure of the pump gradually rises. High, the final pump pressure reaches 30, there is still 45 flow, and the measured group data is basically consistent with the constant pressure variable characteristics of the pump, indicating that the pump performance is good. In order to improve the location of the fault, a portable hydraulic tester is connected between the control valve and the hydraulic cylinder to test the actual flow rate of the hydraulic pump output flow through the overflow valve and the multi-way valve to the hydraulic cylinder. When the pressure reaches 12, the flow rate measured to the hydraulic cylinder is still 5, compared with the flow output when the hydraulic pump is tested. After the hydraulic oil passes through the relief valve and the control valve, there is only 5 LAnin leakage, the flow relief valve and the operation. The valve performance is good. In order to verify its accuracy, the pressure regulating valve on the right-handed tester is boosted. When the pressure reaches 30 MPa, the flow rate is 381. It is confirmed that the relief valve and the operating valve are good, and thus the piston of the hydraulic cylinder is The seal is severely scratched. After replacing the sealing ring, the pump works normally and the pressure can reach 30MPa. In the actual work, the portable hydraulic tester was used to check and diagnose the hydraulic system faults of construction machinery such as domestic hydraulic excavator of road roller stabilized soil mixing machine, and the effect was very good. The accuracy rate was 100, in order to shorten the maintenance time and reduce the downtime loss. Played a very important role. Address: Xi'an Tongli Hydraulic Electromechanical Co., Ltd. Xi'an Hongqing, 8 Crane Lifting Telescopic Hydraulic Cylinder Repair China Railway Tunnel Group Machinery Factory 耿æ¦1 Accident Introduction Our unit Taiwan factory produces a type 8 crane, When the construction of the Neijiang-Kunming Railway construction site was carried out, it was accidentally tipped over, causing serious damage to the boom-type boom of the boom and the cylinder of the hydraulic cylinder that controlled the simultaneous expansion and contraction of the boom. However, since the hydraulic cylinder piston rod is fully extended during tilting, the piston rod and the piston portion are not damaged. The damage of the hydraulic cylinder is about 18, and the outer wall of the cylinder has a depression, the depth is about 2mm, and the roundness error of the bend is up to 3mm. Due to the limitations of the conditions, it was impossible to repair the crane. In order to restore the crane to use as soon as possible, after repeated research, it was decided to correct the rounding and depression by the cold orthopedic method to correct the bending and heating. 2 Design and calculation of the repair plan 2.1 The main parameters of the hydraulic cylinder The total length of the cylinder barrel and the outer diameter of the cylinder! 2.2 Calculate the corrective bending moment of the orthopedic force at the midpoint of the bending cylinder. The following relationship is MM, h=JiD4d4oJ32D, the bending section modulus of the TF hydraulic cylinder, d is used to estimate the outer diameter of the D cylinder, m F=F , +F22.3 fulcrum design Because the wall thickness of the hydraulic cylinder is only 1 under the action of orthopedic force, it will cause partial depression. Therefore, the contact area between the force application point and the fulcrum should be large enough, so a semi-circular bearing should be designed. Support the bearing wall of the cylinder. To avoid localized depression of orthopedics, the following empirical formula n safety factor should be satisfied. Take the tensile strength of 5CTb cylinder material D cylinder outer diameter s cylinder wall thickness Pc orthopedic force, the pressure on the cylinder wall is obtained, the bearing bush The length of the 242.4 bearing bush rolling bearing is designed so that the hydraulic cylinder can be freely extended without restraint after the jack is applied, and the bearing bush must be provided with a rolling bearing. When straightening, the cylinder tube will form a compression bending under the static state. This is very important. After orthopedic straightening, the extension of the working distance is 2.5 straightening device straightening force point position 3. 2.6 special tools for the design of partial depression and out-of-round treatment of cylinders 4. 1. Workpiece barrel 2. Outer taper sleeve 3. Inner cone 4. Limit top tube 5. Pull rod 6. Cylinder head 7. Gasket 8. Nut operation method Tighten nut 8, then the rod 5 drives the inner cone 3 to the right. And relying on the conical surface contact with the outer taper sleeve 2, the outer diameter of the outer taper sleeve 2 is swollen, and the cylinder recess is flattened. At the same time, in order to eliminate the stress and smoother, it can be heated with oxyacetylene flame at the top expansion and tapped by hand. After the top expansion is completed, remove the heat source, keep warm and cool, and avoid chilling. 3 Effect After the repaired hydraulic cylinder is cleaned and assembled, the factory test is carried out, and the requirements of the manufacturer's working conditions can be met under various lifting conditions. The crane has been in use for more than a year and there is no such problem with this telescopic hydraulic cylinder. Practice has proved that the above repair method is successful. The address of the China Railway Tunnel Group Machinery Factory in Hebei Province, Yanjiao Town, is disconnected on page 37 to ensure that the internal network is protected from external attacks, and the leakage of technical data and core information of the enterprise can be prevented. After downloading the necessary information, after processing to confirm that the downloaded content is secure, the administrator will post it to the internal network for the personnel of each department to check and call. If you want to open your own website, you can consider renting a virtual 8 server at 18 suppliers to ensure the security of the company's network and reduce the cost of maintaining the website. 4 printer plotter management, all output of the design must be printed on the printer or plotter. Therefore, the printing paper is the main content of the daily work of the central computer room. The printing paper needs to fill in the printing paper application form in advance, and indicate the width. The ratio can be submitted after approval by the competent authority. The printer and the plotter are shared on the network, but the special print manager is responsible for setting the password. The normal user does not have the print permission, which can eliminate the disorder. Address: Luoyang Construction Machinery Co., Ltd., Luoyang Zhongzhou, Henan
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