Outline of crane hook blocks:
The lifting hook group is the most commonly used device, which consists of hook, movable pulley, pulley shaft and bearing.
The fixed pulley, which works with the hook group, is fixed to the structure and consists of a pulley block.
1. Forging hook
There are single and double hooks.
Generally use 20, 20MnSi steel as a whole.
The single-hook eccentricity is less advantageous than the symmetrical force of the double hook, so it is necessary to use single hook for small tonnage cranes under 75 tons, and more than 75 tons of large-tonnage cranes with double hooks.
This kind of hook application is widely used and has been a system.
In general case, do not need to calculate, can press table to choose directly.
A safety hook should be set when the wire rope is in danger of decoupling.
Second, the hook hook
The hook can be divided into single hook and double hook.
It is generally used to rivet the plates with C3 and 16Mn plates.
The hook structure is simple, reliable and convenient for maintenance.
Single hook used for casting crane, double hook for more than 100 tons of general crane.
They have a series of structural dimensions, and they do not need to be calculated.
The lifting ring is better than the hoisting hook, the weight is the same, it's weight is lighter, but the use is not as convenient as the hook, so the use of the rings is not as common as the hook.
It is mainly used on cranes with heavy work and heavy weight.
Its structure has integral and hinged type two kinds, latter USES more.
The calculation of the crane hook block
1. Determination of calculation load
The hook is usually calculated with the allowable stress.
Its calculation load is:
Q = 'bits Ⅱ Qe (kg)
In the formula: Qe -- -rated weight [kg];
Bits of Ⅱ - power coefficient.
The design hook is generally a preselected cross section, and then it is checked.
2. Check calculation of forging hook
According to the force analysis, to make full use of the hook material and make it have a simpler process, its cross section is made into trapezoid.
The size of B -- B is the same as the size of A -- A has A greater intensity than A -- A, so section A -- A is the most dangerous.
The basic parameters and main dimensions of the crane hook block