154HC Mast Section Analysis of Causes, Hazards and Precautionary Measures of Loose of Stair Sling Standard Connection Bolt
The tower crane standard section is attached to the tower crane's own overhead device, and a section of assembly forms the "trunk" of the tower crane, which acts as a support for the upper working parts, mainly bearing the axial pressure from the top working parts. Horizontal force, bending moment and torque. The standard bolt loosening of the tower crane is a tower body that adopts the form of bolt sleeve connection between the standard joints. At present, most small and medium-sized tower cranes(60t · M and below) of the tower crane manufacturers use this form of connection, and the bolts are all high strength bolts. However, in the daily inspection of the tower crane, there are many cases where the connection bolt is loose. What is the reason why the standard bolt of the tower crane is loose? Below, the following discussion is made on the analysis of the causes, hazards and preventive measures of the loose bolt of the standard joint of tower crane.
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The reasons for the loose bolt of the standard joint connection of the tower crane:
We first analyze the force characteristics of the tower body. The force of the tower body can be simplified to: moment M perpendicular to the horizontal plane, torque T in the horizontal plane, axial pressure N, horizontal force F, in which M, T has a greater impact on bolt loosening.. When the boom is lifted, M is positive, and M is negative after the weight is put down. The T generated at the turn start is positive, and the T generated at the turn brake is negative. During normal work, the tower crane frequently lifts and puts down heavy objects, and the crane arm is repeatedly started and braking, so that the tower body suffers from frequent changes in the moment and torque of positive and negative alternation, resulting in repeated changes in the force of the standard joint connection bolt. This is the fundamental reason why the bolt is loose. The working characteristics of the tower crane determine the force characteristics of the standard joint joint bolt, which is insurmountable. For this reason, each tower crane manufacturer adopts high strength bolts to the tower crane standard joint bolt.
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