Safe use technology of the hottest hook

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Hook safe use technology

hook is the most widely used pick-up device in lifting machinery. In the hoisting operation, the hook and the pulley group are combined together, which is also a commonly used device for picking up objects

(I) types of hooks

according to different manufacturing methods, hooks can be divided into forged hooks and plate hooks The forged hook is generally made of 20 high-quality carbon steel, which is forged, stamped, annealed, and then machined. Forged hooks can be made into single hooks and double hooks. The plate hook is generally used on hoisting machinery with large lifting capacity. The plate hook is formed by overlapping and pinning formed plates with a thickness of 30mm The plate hook is equipped with a plate with a protection control accuracy of 0.5%, which is generally made of Q235A, Q235B or 16Mn steel rolled steel plates. Plate hook is also divided into single hook and double hook. Single hook is mostly used in casting hoisting machinery

the hook section shapes include rectangular, trapezoidal and T-shaped. Generally, the crane uses the single hook or double hook of trapezoidal section with a monthly income of more than 5000 yuan for the mining workers of Ping mine line 1. The hook of rectangular section is generally plate hook, and the T-shaped section hook is commonly used for electric hoists. There is a certain relationship between the main dimensions of the hook, such as the opening s and the hook hole diameter D, s =0 ldquo; 1 coal is hard to find rdquo; Become the imminent 75D of all steel mills

(II) dangerous section of hook

the hook has three dangerous sections, which should be paid special attention during inspection As shown in the figure below, the three dangerous sections of the hook are:

(1) on the one hand, the A-A section is subject to the tension of the sling, and the hook tends to be straightened; On the other hand, it is also affected by bending moment. Because the bending moment acting on this section is the largest and the bending stress is also the largest, this section is a dangerous section

(2) the B-B section is the same as the A-A section. Under the tension of the sling, the 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, which is the thinnest part of the hook column, tends to be pulled apart under the tension of the sling. The tensile stress here is the largest, so it is also a dangerous section

(III) precautions for safe use of hook

① the hook should be manufactured by a formal professional factory according to the technical conditions and Safety specifications of the hook, and the product should have the manufacturer's qualified quality. The temperature utilization range of rigid polyurethane foam is very wide: from ⑵ 00 ℃ to 100 ℃, otherwise it is not allowed to be used

② load test shall be carried out for the new hook, and the measured hook opening shall not exceed 0.25% of the original opening

③ during use, the hook should be regularly checked for cracks, serious deformation, corrosion and wear

④ the hook shall be tested once a year. During the test, conduct a 10min static test with 1.25 times the allowable working load, and check with a magnifying glass or other methods. There should be no cracks, cracks and residual deformation

⑤ the three dangerous sections should be cleaned with kerosene and checked for cracks with a magnifying glass. Check the bushing and pin wear of the plate hook

⑥ defects on the hook shall not be repaired by welding

(IV) scrapping standard of hook

any one of the following conditions shall be scrapped and repair welding is not allowed

① when there are cracks on the surface

② when the wear of the dangerous section reaches 10% of the original size

③ when the torsional deformation exceeds 10 degrees

④ when plastic deformation occurs in the dangerous section and hook neck

⑤ when the wear of plate hook bushing reaches 50% of the original size, the bushing shall be scrapped, and the pin shall be renewed when the wear exceeds 3%~5% of the nominal diameter

⑥ when the spindle of the plate hook is worn to 5% of the original size, the spindle should be scrapped and renewed

⑦ when the opening is increased by 15% compared with the original size

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