Introduction of hook
The classification of hooks is very wide, generally including shackles, rings, sheet hooks, forged hooks, round rings, pear-shaped rings, rings, combined rings, S hooks, nose hooks, American hooks, claw hooks , Eye-shaped sliding hooks, bolts with safety card rings, chain shackles, etc. Now the following three are mainly introduced:
There are two types of sheet hooks, single hook and double hook, which are generally formed by overlapping multiple pieces of C3 and 16Mn steel plates. The hook has simple structure, reliable work and convenient maintenance. Single hooks are mostly used in casting cranes, and double hooks are mostly used in general-purpose cranes over 100 tons.
Forged hooks are divided into single hooks and double hooks. It is generally forged from 20, 20MnSi steel as a whole. Because the single hook is eccentric, the force is not as good as the symmetrical force of the double hook, so the small and medium tonnage cranes below 75 tons mostly use single hooks, and the large tonnage cranes above 75 tons use double hooks. This kind of hook is widely used and has formed a series. Used for safety hooks when the wire rope is in danger of unhooking.
The lifting ring is more advantageous than the hook. When the lifting weight is the same, its own weight is lighter, but it is convenient to use without the hook, so the use of the ring is far less common than the hook. It is mainly used on cranes with frequent work and heavy lifting capacity. Its structure is divided into two types: integral type and articulated type, the latter is used more frequently.
Reasons for falling of lifting hook
The falling of the hook will bring great safety hazards to people's personal safety. Before and during the operation, attention should be paid to any factors that may affect the safety of the hook:
1. Irregularity of the hook
1.1 Risks caused by non-standard design, such as failure of overload protection, unreasonable selection of slings, etc.;
1.2 Manufacturing defects and installation defects, etc., make the equipment with hidden dangers put into use.
2. Human unsafe behavior
2.1 It is manifested as unskilled operation skills and lack of necessary safety education and training;
2.2 Undocumented employment;
2.3 Violation of rules and disciplines, brutality, bad operating habits;
2.4 Misjudgment operation, unclear command signal.
3. Environmental factors
3.1 Unfavorable environments that exceed safety limits or sanitary standards, such as high dust, high temperature, high humidity, low temperature, high noise, windy days, poor lighting, etc., will be distracting and directly affect the response of the operators. The stability of ability and technology has increased the chances of misoperation and illegal operations, leading to accidents.
3.2 Poor operating environment will also cause the function of the crane system itself to decrease and even accelerate the failure of parts (structures), which becomes one of the unsafe factors.
4. Security management defects
4.1 Lack of crane management, inspection and regular safety performance inspection;
4.2 Lack of safety education and training of relevant personnel, the establishment of crane safety operation regulations, establishment of violation reward and punishment system, and emergency response plans;
4.3 Lack of regular inspection of lifting equipment and lifting aids, lack of effective monitoring and management, etc.
n short, strengthening the safety education and training of crane-related personnel and conducting regular inspections on the safety performance of cranes (including lifting accessories) in use are necessary guarantees to reduce the occurrence of accidents caused by falling objects on crane hooks.
Daily maintenance of hook
To eliminate the hidden dangers of hook safety, maintenance is the most indispensable. Daily inspection and maintenance include the following:
1. Wipe the main hook clean;
2. Lubricate pulleys, rotating parts and other parts with grease nipple;
3. Check all bolts and screws to ensure that all cotter pins are complete and the opening is opened;
4. Check whether the pulley groove and rim are evenly worn, whether the wire rope matches the groove, and whether the pulley is loose or shaking;
5. Ensure that the rotating part of the hook rotates freely, and the gap cannot be too large. If the rotation is difficult or there is a feeling of jamming, you need to check whether the bearing or sleeve is damaged or insufficient lubrication;
6. Check the overload damage of the main hook;
7. Check the side plate elongation, aperture elongation, bolt bending or elongation, cracks, etc.;
8. Check the anti-decoupling device.
Carry out the daily maintenance of the hooks to eliminate some hidden dangers in the bud. This is not only responsible for the progress of the project, but also for the lives and property of the constructors.
Check each hook body
The hook body shall be inspected at least once a year, using colored flaw detection, magnetic particle flaw detection, ultrasonic flaw detection or X-ray flaw detection. Check whether the hook is deformed, local cold deformation, crushed, cracked, worn, and rusted jaws. Lock the joint of the hook nut.
Deformation：If the claw increases by more than 10% compared to the original size, the hook must be replaced. The original size is recorded on the hook. Measure them one by one.
Corrosion：The threads and the operated shaft must be checked for corrosion and wear. For this, the hook nut on the shaft must be loosened.
If reprocessing is required to remove corrosion, the process must not cause the thread core diameter to exceed 5%, otherwise, the hook must be replaced. Failure to replace obsolete parts in time and lack of necessary safety protection and maintenance are irresponsible to oneself.
It should be scrapped when the following situations occur
1. The opening of the crane hook is larger than the original size;
3, the wear of the dangerous section reaches 10% of the original size.;
4. The opening degree is increased by 15% compared to the original size.;
5, the torsion deformation exceeds 10°;
6, the dangerous section or the neck of the hook is plastically deformed;
7. When the plate hook bushing wears up to 5% of the original size, the bushing should be scrapped;
8. When the plate hook mandrel wears up to 5% of the original size, the mandrel should be scrapped;
9. It was found that the hook welding and other hooks were subjected to high temperature, strong corrosion, and exceeding the company's regulations.
10. Defective hooks must not be used, and welding methods must not be used to repair the hooks.
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