| Flat-head tower crane’s luffing motion generally depends on the traction mechanism to drive the wire rope to drag and lift the trolley to move forward and backward along the boom track to complete the amplitude movement.At present,it is mainly divided into two types of winch and friction type traction mechanism,one is dependent on the winding machine roll Around the traction,a friction traction by the pull mechanism.The friction type traction mechanism is superior to the traditional winch type traction mechanism in that the advantages thereof are particularly short in shortening the length of the required steel wire rope,adopting the driving wheel to avoid the reel from being too long,and the structure is compact,and it is easy to adjust the length of the wire rope.The disadvantage is that it can allow the drive wheels to slip,which can cause abnormal wear of the wire ropes and the drive wheels or pulleys,resulting in a cumulative error in the range feedback and affecting the amplitude accuracy.Therefore,it is necessary to systematically study the key technologies affecting the friction-type traction mechanism of the horizontal-arm tower crane for the above problems.This article combines the engineering practice,with the engineering application of the FHTT flat-top tower crane series products as the research subject,according to the characteristics of the friction-type traction mechanism above,systematically analyzes and studies a number of contents: the determination of the amplitude power of the friction-type traction mechanism,based on the Workbench The static analysis of the key parts of the friction traction mechanism,using MATLAB software to simulate the main factors affecting the traction force,design the friction slip test to verify the theoretical calculation results of the maximum traction force,analyze other factors that affect the traction force and optimize and improve the traction The organization and the final project have targeted the practical problems encountered in engineering applications such as abnormal wear of traction wire ropes.The study concludes that the characteristics of over-slipping of the friction traction mechanism can effectively prevent the traction steel wire rope from breaking due to overload,resulting in the occurrence of the load-carrying forward movement of the lifting trolley;the safety margin of the friction-type traction mechanism should be fully reserved for safety design.Reasonable number of drive wheel drive slots can effectively avoid traction wire rope slip;Undercarriage and drive shaft are important load-bearing components of tower crane luffing mechanism,it is necessary to use finite element method for precision Calculate and analyze;derive the comprehensive change curve of traction force,wire rope wrap angle,driven end tension force,and static friction coefficient;verify the theoretical results of the maximum traction force calculated by Euler’s formula through the friction traction mechanism slip test and the experimental data are basically the same According to the feedback in practical application,some suggestions for improvement of this type of friction type traction mechanism are put forward,and the corrective and preventive measures to solve the traction wire rope slipping can be added by means of increasing the tail rope pressure rope device.The research results of this subject have been successfully applied to the variable amplitude mechanism of the typical flat-arm tower crane FHTT1000,and have achieved good results,which provides a useful reference for the design of the similar-type tower crane luffing mechanism. |
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