What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
When the nut is tightened on the stud, there will inevitably be an empty upstroke. That is, when the nut has not reached the part that needs to be tightened, the nut needs to be twisted on the non-locking (working) part of the front end of the stud by hand or tool, so that the nut runs along the axial direction of the stud and reaches the part to be locked. . When the idling stroke of the thread at the front end of the stud is long or the thread pitch is small, the idling stroke before locking will waste a lot of time, resulting in a huge occupation of personnel or tools.
When fixing the centrifugal fan, since the gaskets, washers and nuts are separate parts, many parts are used in the whole process, and it is easy to miss the installation of parts; The volume of the parts is relatively small, and it is not easy to remove them when they are transferred into the air conditioner through the gap of the centrifugal fan blades, resulting in foreign bodies in the machine.
The materials of rubber gaskets are usually NBR (nitrile butadiene rubber), SBR (styrene butadiene rubber), HNBR (hydrogenated nitrile butadiene rubber), EPDM (EPDM rubber), SILICONE (silica gel), VITON (fluorine rubber), CR ( Neoprene), FFKM (perfluoroelastomer), etc.
In the past production, gaskets were generally obtained from two channels: first, standard gaskets were mostly purchased from the market, and the cost was high; non-standard gaskets, due to the small demand, required separate tooling and molds, which were expensive and long production cycle. It is difficult to purchase; Second, the plate is purchased by the enterprise, and then the washer is formed by the automatic cutting machine. Because the cut nodules and cut marks produced by flame cutting do not meet the requirements for use, the inner and outer diameters need to be reserved 2 ～3mm machining allowance, and then finish the outer diameter and inner diameter by lathe.
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