As heavy mechanical equipment, a crane is a material lifting tool, and the crane hook is an important part of the crane to carry goods, which plays a very good role in the lifting and handling of heavy objects in the operation. We will give you a detailed introduction to the types of crane hooks, and use and purchase tips for crane hooks.
Generally speaking, according to the shape, the crane hook of the overhead crane and gantry crane can be divided into a single hook and a double hook. If it is from the manufacturing method, it can be divided into forged hook and sheet hook. The single hook is easy to manufacture and use, and is often used for lifting objects with relatively light weight; while the double hook weighs a lot, and is generally used for lifting objects with heavy weight. Generally, forged single hooks are mainly used for lifting cranes below 30T, double hooks are used for lifting cranes of 50T-100T; sheet single hooks are used for lifting 75T-350T cranes, and double hooks are used for lifting cranes above 100T.
Let’s take a look at the cross-sectional shape of the crane hook body. Generally, there are round hooks, square hooks, trapezoidal hooks, and “T” shapes of hooks. According to the analysis of the stress situation, the “T” cross-section design is reasonable, but the forging process is also more complicated; the trapezoidal cross-section is more reasonable in stress and easy to forge, while the rectangular (square) cross-section is only used for sheet hooks. The bearing capacity is not fully utilized, it is bulky, and the circular section is only used for small hooks.
As for the forging of the tail of the crane hook, if triangular threads are used, due to the serious stress concentration of this structure, it is easy to break at the cracks, so trapezoidal or zigzag threads are often used at the tail of large hooks.
The single hook is simple to manufacture and easy to use, but the force is not good, and it is mostly used in workplaces with a lifting capacity of less than 80 tons cranes; when the lifting capacity is large, a double hook with symmetrical force is often used. The laminated hook is riveted by several cut and formed steel plates. When individual plates crack, the whole hook will not be damaged, and the safety is better, but the weight is relatively large. Most are used for lifting large lifting capacity or molten steel drums on the crane. The hook is often impacted during operation and must be made of carbon steel with good toughness.
1. The purchase of crane hooks should have the technical documents such as the manufacturer’s certificate before they can be used; important departments purchase hooks such as: railways, ports, etc., and the hooks need to be strictly inspected (flaw detection) before leaving the factory.
2. The crane hook must not have defects that affect the safety performance; the defects of the hook must not be repaired by welding; the surface of the hook should be smooth, and there must be no cracks, folds, sharp angles, burrs, peeling, over-burning and other defects.
3. Two suitable positions can be selected at the shortest distance from the crane hook opening to print non-wearable marks, and the distance of the marks can be measured as a basis for detecting whether the opening degree changes during use.
4. The crane hook material can be made of forged 20* quality carbon steel or hook special material DG20Mn, DG34CrMo, etc. It is strictly forbidden to use cast hooks. The material of the plate hook is generally A3, C3 ordinary carbon steel, or 16Mn low alloy steel.
5. The technical conditions of self-made hooks should meet the requirements of GB 10051.1-88~GB 10051.5-88 (new standard: GB10051.1-2010~GB 10051.5-2010).
6. The longitudinal axis of the crane hook piece of the plate hook must be located in the rolling direction of the steel plate, and the hook pieces are not allowed to be spliced.
7. The crane hook plate of the plate hook should be riveted with countersunk rivets, and the high-stress bending part where the plate hook contacts the lifting point of the lifting object must not be connected with rivets.
8. Fully enclosed welding is not allowed between plate hook lamination, only intermittent welding is allowed.
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