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General requirements for duct production
1. Selection of the duct flange connection
If the thickness of the thin steel air duct is less than or equal to 1.2mm, it should be connected by lock roll forming;
For steel plate thickness more than 1.2mm, welding can be used. Galvanized steel duct, the plate thickness is less than or equal to 1.2mm, use lock forming connection; for plate thickness greater than 1.2mm, use rivet connection pick up made of stainless steel plate air duct, the plate thickness is less than or equal to 1mm, and the joint is connected. The plate thickness is more than 1mm and welding is adopted.
Made of aluminum plate air duct, the plate thickness is less than or equal to 15mm, and the joint is connected; The thickness of the plate is more than 1.5mm, and the width of the lock forming is large, which is not conducive to mechanical processing.
The sealing of the air duct is mainly realized by the sealing when the plates are connected.
When the requirements are high, apply sealant to caulking the bite seam, and the sealing surface should be set on the front of the air duct.
When making metal steel ducts, the splicing seam lock of the plate and the closed seam lock of the circular duct can be drive cleat; rectangular duct or four-corner combination of accessories can use corner, joint angle, snap seam clock; the combination of round elbow can use vertical seam lock. Making duct at the same time, the board surface should be kept flat, and the angle of the four sides should be strictly controlled to prevent phenomena such as distortions and angles. The lock seam should be tight and uniform in width, and the longitudinal seams should be staggered
The splicing surface of the duct plate should be flat, the lock seam should be tight, and the width should be consistent and setting distance.
There must be no crisscross stitches. If the splicing of the plates is welding, the in addition to the welding process shown in Figure 4-8 to prevent deformation, the plate should be dealt with after welding the deformation should be corrected. The welds should be visually inspected, and there should be no pores, slag inclusions, or cracks defects such as seams.
2. Control of the deviation of the processing length and outer diameter (or outer side length) of the air duct
The length of the circular and rectangular ducts should be based on actual needs and the specifications of the plate however, the length of the general pipe section is 1.8~4.0m. The processing length of the duct should be longer than the actual measurement the calculated length is 30~50mm.
The allowable deviation of the outer diameter or outer length of the duct should be controlled according to the negative deviation: when the outer diameter or outer when the side length is less than or equal to 300mm, it is -2~0mm; when the outer diameter or outer side length is greater than 300m is -3~0mm. The allowable deviation of nozzle flatness is 2mm, rectangular wind the difference between the lengths of the two diagonals of the pipe should not be greater than 3mm; the round flange is arbitrarily orthogonal the difference in diameter should not be greater than 2mm.
3. Relevant regulations for the production of metal flange connection ducts
(1) The allowable deviation of flange flatness is 2mm, and the screw holes of the same specification flange the arrangement should be consistent and interchangeable. The welding seam of the flange should be well fused.
(2) When the air pipe and the flange are connected by riveting, there should be no riveting and missing riveting; The pipe flanging should be flat, close to the flange, and the width should be the same, and it should not be less than 6mm. There should be no cracks and holes at the four corners.
(3) When the air pipe and the flange are connected by welding, the end face of the air pipe shall not be higher than the flange interface plane. The air duct of the dust removal system should adopt the shape of full welding on the inside and intermittent welding on the outside.
Type, the end face of the air pipe should not be less than 5mm from the flange interface plane when the air pipe and the flange are fixedly connected by spot welding, the welding points should be well fused, and the spacing it should not be greater than 100mm; the flange and the duct should be close to each other, and there should be no gaps or holes.