What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In order to achieve the above purpose, Guangdong Yueluo Hardware Industry Co., Ltd. provides the following technical solutions: an anti-drop screw structure, including a connecting bolt and a fastening screw, the connecting bolt includes a connecting screw and a connecting nut, one end of the connecting screw It is integrally connected with the connecting nut, the surface of the connecting screw is provided with an external thread, the connecting bolt is movably mounted with a matching nut, the matching nut and the connecting bolt are connected by thread, and the interior of the connecting screw is provided There is a screw hole along the axis of the connecting screw. The connecting screw is provided with a number of slots along the axis. The slot extends into the screw hole. The screw hole is provided with an internal thread, and the screw hole is movable in the screw hole. A tightening screw is installed, the tightening screw includes a tightening screw and a tightening nut, one end of the tightening screw is integrally connected with the tightening nut, and the tightening screw is connected to the tightening nut through a screw hole Bolted thread connection.
Stainless steel screws are classified into austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and precipitation hardening stainless steel. The selection of stainless steel screws is also based on principles. Where to start, let you choose the stainless steel screws you need. After comprehensive and comprehensive consideration of these five aspects, the grades, varieties, specifications and material standards of stainless steel screws are finally determined. Austenitic stainless steel: the most basic alloying elements of austenitic stainless steel are chromium and nickel. The grade is a chromium-nickel austenitic stainless steel with a chromium content of about 18% and a nickel content of about 8%, often called 18-8 stainless steel. The element ratio of chromium and nickel basically ensures that the structure of the steel is stable austenitic ferritic stainless steel: 430 type ordinary chromium steel, its corrosion resistance and heat resistance are better than 410 type, magnetic, but it It cannot be strengthened by heat treatment, and is suitable for stainless steel screws with slightly higher corrosion resistance and heat resistance and general strength requirements. Martensitic stainless steel: Type 410 and 416 can be strengthened by heat treatment, with a hardness of 35 to 45HRC, and good machinability. They are used for general-purpose heat-resistant and corrosion-resistant stainless steel screws. Type 416 has a slightly higher sulfur content and is a free-cutting stainless steel. Type 420, sulfur content? R0.15%, improved mechanical properties, can be strengthened by heat treatment, maximum hardness value of 53 ~ 58HRC, used for stainless steel screws requiring higher strength. Precipitation hardening stainless steel: 17-4PH, PH15-7Mo, they can get higher strength than the usual 18-8 type stainless steel, so they are used for high-strength, corrosion-resistant stainless steel stainless steel screws. A-286, a non-standard stainless steel, has higher corrosion resistance than commonly used Type 18-8 stainless steels, as well as good mechanical properties at elevated temperatures. Used as high-strength, heat-resistant, corrosion-resistant stainless steel screws, can be used to 650 ~ 700 ℃. Austenitic stainless steel: The commonly used models are 302, 303, 304, and 305, which are the so-called 18-8 austenitic stainless steels. Both corrosion resistance and mechanical properties are similar. The starting point of selection is the production process method of stainless steel screws, and the method depends on the size and shape of stainless steel screws, and also depends on the quantity of production. Type 302 is used for machined screws and self-tapping bolts. Type 303 In order to improve machinability, Type 303 stainless steel is added with a small amount of sulfur and is used to machine nuts from bar stock. Type 304 is suitable for hot heading stainless steel screws, such as longer gauge bolts, large diameter bolts, which may be beyond the scope of the cold heading process. Type 305 is suitable for cold heading processing of stainless steel screws, such as cold formed nuts, hex bolts. Type 309 and Type 310, their Cr content and Ni content are higher than 18-8 type stainless steel, suitable for stainless steel screws working at high temperature. Types 316 and 317, both of which contain the alloying element Mo, have higher high temperature strength and corrosion resistance than 18-8 type stainless steel. Type 321 and Type 347, Type 321 contains a relatively stable alloying element Ti, Type 347 contains Nb, which improves the intergranular corrosion resistance of the material. It is suitable for stainless steel standard parts that are not annealed after welding or serve at 420～1013℃.
The nuts of some products must be installed on the outside, but due to the small internal space, when the indenter of the riveting machine cannot meet the strength requirements by methods such as riveting and budding, riveting and riveting are impossible. Rivets to be nailed. Applicable to the fixed field of each thickness plate and tube (0.5MM-6MM). Using pneumatic or manual riveting equipment, rivet once and it is easy to secure. Replacement of the existing welding nut to supplement the metal plate, the thin tube welding is easy to melt, and the welding nut is not smooth.
The main function of the spring washer is to prevent the nut from loosening. It is also known that: the existing spring washer is a ring made of spring steel, and then a gap is cut in the diameter direction on the ring, and the heads on both sides of the gap are cut. The material of the part is turned to two different sides of the ring to form a pawl, and the purpose of preventing loosening is achieved by the fit between the pawl and the nut on the surface and the workpiece. Obviously, only one pawl is used to achieve the purpose of preventing loosening. Since the braking force generated by one pawl is limited, there are defects of poor braking effect and poor anti-loosening effect.
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