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Method and device for changing prestress of lifting arm of flat-head tower crane

A technology for flat-top tower cranes and booms, applied in the field of a method and its devices, can solve the problems of large boom bending moment and weaken the lifting capacity of flat-top tower cranes, and achieve the effect of improving the lifting capacity

Active Publication Date: 2012-08-15
SHANDONG FORYOU +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the mass of the boom and balance arm of the flat-top tower crane is 5% to 15% heavier than that of ordinary tower cranes of the same level, resulting in a large downward bending moment of the boom, which greatly weakens the lifting capacity of the flat-top tower crane

Method used

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  • Method and device for changing prestress of lifting arm of flat-head tower crane
  • Method and device for changing prestress of lifting arm of flat-head tower crane
  • Method and device for changing prestress of lifting arm of flat-head tower crane

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Experimental program
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Effect test

Embodiment 1

[0020] The method of changing the prestress of the jib of the flat-top tower crane by changing the position of the balance jib cable and the hinge point of the balance jib by using the above-mentioned device is as follows:

[0021] First of all, according to the principle of moment balance, take the moment of two points A and B, let G be the weight of counterweight 1, F1 be the tension force of balance arm cable 3, F2 be the tension force of boom cable 6, and L1 be the difference between point A and G Moment arm, L2 is the moment arm of point A to F1, L3 is the moment arm of point B to F1, L4 is the moment arm of point B to F2, then the moment balance formula of point A is , the moment balance formula at point B is , and the two formulas are sorted out to get the calculation formula of the boom cable tension F2 as (1);

[0022] Then, point C is analyzed again, and the angle between the boom cable 6 and the horizontal direction is θ, then the pulling force F2 can be de...

Embodiment 2

[0024] The method of changing the prestress of the jib of the flat-top tower crane by changing the position of the jib cable and the jib hinge point by using the above-mentioned device is as follows:

[0025] First of all, according to the principle of moment balance, take the moments of two points A and B, let G be the weight of the balance weight 1, F1 be the tension force of the balance arm cable 3, F2 be the tension force of the boom cable 6, and L1 be the force of point A on G L2 is the moment arm of point A to F1, L3 is the moment arm of point B to F1, L4 is the moment arm of point B to F2, then the moment balance formula of point A is , the moment balance formula at point B is , and the two formulas are sorted out to get the calculation formula of the boom cable tension F2 as (1);

[0026] Then, point C is analyzed again, and the angle between the boom cable 6 and the horizontal direction is θ, then the pulling force F2 can be decomposed into F2 perpendicular t...

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Abstract

The invention relates to the technical field of a flat-head tower crane, in particular to a method and a device for changing prestress of a lifting arm of the flat-head tower crane. An inhaul cable structure is arranged on each of a balance arm and a lifting arm; the computational formula of the inhaul cable pulling force of the lifting arm is obtained according to the moment balance principle; so that the component force of the inhaul cable pulling force of the lifting arm on the vertical direction causes a bending moment on the root part of the lifting arm opposite to the gravity and loading direction of the lifting arm; and the bending moment can enable the lifting arm to generate a prestress. Therefore, the pulling force of the lifting arm inhaul cable can be changed by adjusting the position of the hinged points of the inhaul cable and the balance arm or the lifting arm to further change the prestress of the lifting arm so as to improve the lifting capacity of the lifting arm.

Description

technical field [0001] The invention relates to the technical field of flat-top tower cranes, in particular to a method for changing the prestress of a jib of a flat-top tower crane and a device used therefor. Background technique [0002] Tower crane is an important equipment for the modern construction industry to realize production mechanization and automation, reduce physical labor intensity and improve production efficiency. Flat-top tower cranes without tower caps are more and more used in the construction industry due to their advantages such as low installation height, simple loading and unloading, and simple stress on the steel structure of the boom and long life. However, the mass of the boom and balance arm of the flat-top tower crane is 5% to 15% heavier than that of ordinary tower cranes of the same level, resulting in a large downward bending moment of the boom, which greatly weakens the lifting capacity of the flat-top tower crane. Contents of the invention ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B66C23/72
Inventor 王积永宋世军
Owner SHANDONG FORYOU
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