The hook is divided into single hook and double hook by shape;
According to the manufacturing method is divided into the forging hook and the stack hook.
Single hook is simple to manufacture, easy to use, but the force situation is not good, most of them are used in the workplace with a lifting weight of less than 80 tons;
Double hooks with symmetrical force are often used for heavy lifting.
Laminated sheet hook is composed of several pieces of cutting formed steel plate riveted. When cracks appear on some plates, the whole hook will not be damaged, and the safety is better.
The hook is often impacted during operation and must be made of high quality carbon steel with good toughness.
Hook classification, generally includes: the shackle, ring, ring, pear ring, long rings, composite rings, S hook, hook nose, American hook claw hook, eye shape slip, insurance card lifting bolt, shackle chain, has the characteristics of unique, innovative, high quality, safety, applicable to factories, mines, oil, chemical industry and dock, etc.
Ensure safety, quality safety factor, static load up to 3 times.
The lifting weight is from 5 to 150 tons.
The technical requirements
1. The purchase hook shall be provided with the manufacturer's certificate of quality and other technical documents before use;
Hangers purchased by important departments, such as railway, port, etc., shall be strictly inspected (inspection) before delivery.
2. The hook shall not have any defect affecting the safety performance;
Defects of the hook shall not be soldered;
The surface of the hook should be smooth and free from defects such as cracks, folding, sharp angles, burrs, peeling and overburning.
3. Two suitable positions can be selected at the shortest distance of the hook opening to print marks that are not easy to wear, and the distance of marks can be measured, which will be used as the basis to check whether the opening degree changes during use.
4. The hook materials can be forged by 20 quality carbon steel or special materials for the hook, such as DG20Mn and DG34CrMo. Casting hooks are strictly prohibited.
The material of plate hook is usually A3, C3 plain carbon steel, or 16Mn low alloy steel
5. The technical conditions of the self-made hanger shall comply with the provisions of GB 10051.1-88 ~ GB 10051.5-88 (new standard: gb10051.1-2010 ~ GB 10051.5-2010)
6. The vertical axis of the plate hook plate must be located in the rolling direction of the steel plate.
7. The plate hook and hook piece shall be riveted with countersunk head rivet, while the high-stress bending part between the plate hook and the lifting point shall not be connected with rivets.
8. Full sealing welding is not allowed between plate hook laminations, only intermittent welding is allowed.
9. The lifting hook that has been overburdened shall be scrapped.
The hook has three dangerous sections, which should be paid special attention during inspection. As shown in the following figure, the three dangerous sections of the hook are:
(1) the a-a section is affected by the sling tension on the one hand, and the hook tends to be straightened;
On the other hand, it is also affected by the bending moment.
This section is a dangerous section because it has the greatest bending moment and the greatest bending stress.
(2) the b-b section is the same as a-a section. Under the action of sling tension, b-b section tends to be straightened and sheared. The shear stress here is the largest, so it is also A dangerous section.
(3) c-c section. This section is the thinnest part of the hook column. Under the action of sling tension, it tends to be pulled.
The tensile stress is greatest here, so it is also a dangerous section.