When installing the ventilation duct, because the gap between the air duct and the wall and between the air duct and the air duct is deep and narrow, the arm cannot enter into it to operate, which brings about the installation of the screws and nuts at these positions. The following three methods are generally used: one is to directly break the wall for installation, but this method damages the building greatly, and cannot be used for the installation of screws and nuts in the gap between the air ducts; the other is to Set the inner flange in the air duct and connect it with bolts, which will reduce the effective cross-sectional area of the air duct and increase the resistance of the gas flow. Moreover, people need to enter the air duct for construction during installation. Considering the size of the air duct First, the supporting firmware with a high position and no force has certain hidden dangers; third, it is directly ignored and not done, but it is easy to cause the air duct connection is not tight and the air volume loss is large. The above-mentioned methods all have major construction defects, which not only waste a lot of manpower and time in the construction process, but also have the problem of low air supply efficiency.
Screws are commonly found in machinery, electrical appliances and buildings. They are generally made of metal or plastic, cylindrical in shape, and grooves engraved on the surface are called screw threads. The main function of the screw is to join two objects, or to fix the position of an object. Screws can often be removed or re-tightened at will without compromising their efficiency. Generally, the diameter of the top of the screw is larger, and the common ones are round, square or regular hexagon. If the top is regular hexagon, you can turn the screw with a wrench. If the top is round, there will also be grooves on the front of the top, which is convenient for use screwdriver to turn the screw. *The common grooves are one-shaped, cross-shaped and square, and there are other shapes. The grooves of the existing screws are often easy to wear, which makes the screws inconvenient to use and causes the screws to be scrapped. In addition, because the screws have no chip removal The structure makes it difficult for the screw to penetrate other objects, which affects the efficiency of the screw.
There are two grades of hexagonal nuts, one is grade 4.8, ordinary nuts, and the other is grade 8 nuts. For more industry knowledge about nuts, you can read the nut specification table and the national standard specification table of the nut industry. Knowledge of these nut specification sheets and industry standards. Allows us to have a deeper understanding of the nut.
Double-end stud (English name: double-end stud) refers to a cylindrical fastener with threads at both ends. Widely used in electric power, chemical industry, oil refining, valves, railways, bridges, steel structures, automobile and motorcycle accessories, machinery, boiler steel structures, pendant towers, large-span steel structures and large buildings.
For hexagonal nuts, the commonly used standards are: GB52, GB6170, GB6172 and DIN934. The main differences between them are: the thickness of GB6170 is thicker than that of GB52, GB6172 and DIN934, commonly known as thick nuts. The other is the difference between the opposite sides, the opposite sides of DIN934, GB6170 and GB6172 in the M8 nut series are 13MM smaller than the opposite side 14MM of GB52, and the opposite sides of M10 nuts, DIN934 and GB52 are 17MM. The opposite side of GB6170 and GB6172 should be 1MM larger, M12 nut, DIN934, GB52's opposite side is 19MM larger than GB6170 and GB6172's opposite side 18MM is 1MM larger. For M14 nuts, the opposite side of DIN934 and GB52 is 22MM, which is 1MM larger than the opposite side of GB6170 and GB6172, which is 21MM. The other is the M22 nut. The opposite side of DIN934 and GB52 is 32MM, which is 2MM smaller than the opposite side of GB6170 and GB6172, which is 34MM. (Besides the thickness of GB6170 and GB6172 are the same, the width of the opposite side is exactly the same) The rest of the specifications can be used in general without considering the thickness.
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