We are one of the largest and most professional crane manufacturers in China, with total sales of more than 1.6 billion US dollars last year, including sales of 11,000 sets of double-beam and gantry cranes, more than 73,000 sets of single-beam cranes, and more than 100,000 sets of electric hoist and accessories.
We have an advanced, green, whole-industry chain, intelligent manufacturing industrial park, with an investment of 370 million US dollars and more than 4,700 employees, which has been established for more than 20 years.
The structural stiffness requirements of cranes are divided into static stiffness and dynamic stiffness.
Static Stiffness
Static stiffness is characterized by the static elastic deformation of the structure at a certain position when a specified load is applied at a designated location.
(1) Bridge-type cranes (including gantry cranes and ship cranes)
1) When the fully loaded trolley is at the mid-span, the vertical static deflection of the main girder caused by the rated lifting load and the trolley self-weight load at the mid-span, for cranes with low positioning accuracy requirements or those with stepless speed control characteristics; cranes that can achieve acceptable positioning accuracy with low lifting speed and low acceleration.
2) For gantry cranes and ship cranes with cantilevers, when the fully loaded trolley is at the effective working position on the cantilever, the vertical static deflection at that position caused by the rated lifting load and the trolley self-weight load should not exceed I/350 (I is the effective working length of the cantilever).
(2) Tower cranes
Under the rated lifting load, the horizontal static displacement at the connection between the tower body and the boom (or the connection between the boom and the turntable) should not exceed 1.34H/100, where H is the vertical distance from the connection between the tower body and the boom to the rail surface, that is, the free height of the tower body.
Dynamic Stiffness
Dynamic stiffness is characterized by the dynamic anti-deformation ability of the crane as a vibration system, that is, the lowest natural frequency in the vertical direction of the system when the suspended length of the wire rope winding is equivalent to the rated lifting height under full load (referred to as the full-load natural frequency). Generally, only the static stiffness of the structure is calculated for cranes. Dynamic stiffness needs to be checked only in special cases where the vibration of the system affects production operations or when requested by the user.
For electric bridge cranes (including gantry cranes and ship cranes), the full-load natural frequency when the trolley is at the mid-span should not be less than 2Hz.
For portal cranes, the full-load natural frequency should not be less than 1Hz.
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