What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The main purpose is to make industrial products form a fixed one. In use, it often occurs that the teeth cannot be closely attached, and the screw heads are broken if they are locked too hard, or the teeth are not locked tightly and fail to meet the conditions of use, all of which are accuracy problems. . Screws are mass products, not hand-made works of art. In mass production, they are supplied to consumers in order to achieve high precision, stable quality and popular prices. The accuracy of screws is usually 6g (class 2, the American standard IFI is 2A teeth), and the rough screws used in construction projects are 8g (class 3, IFI is 1A teeth). Common types of screws Screw A: Machine Screw: Machine screw B: Tapping Screw: Self-tapping screw (for metal and plastic) B-1: Sheet Metal Tapping Screw. (Iron die self-tapping screw) B- 2: Plastic Tapping Screw. (for plastic, self-tapping screw) C: Wooden Screw : Woodworking screw D: Drywall Screw : Cement wall screw E: Self Drilling Screws (stainless steel drilling screw, composite material drilling screw) F : Expansion screw, four-piece expansion screw, also known as: four-piece gecko. The grades of expansion bolts are divided into: 45, 50, 60, 70, 80. Materials of expansion screws: mainly austenitic A1, A2, A4, 1 stainless steel plate, metal steel plate, galvanized steel plate, engineering installation. 2. Indoor and outdoor installation of metal curtain wall and metal light compartment. 3 Generally, angle steel, channel steel, iron plate and other metal materials are combined for installation. 4. Assembly engineering of car boxes, container boxes, shipbuilding, refrigeration, screw machine equipment, etc. Features: 1. Drilling and tapping, locking is completed at one time, and the bonding force is strong. 2. Save construction time and improve work efficiency. E-1:STAINLESS STEEL SELF DRILLING SCREWS E-2:Bi-Metal Self Drilling Screws Common materials of composite drilling screws a.Low Carbon Steel: carbon steel carbon steel is divided into low carbon steel, medium carbon steel, high Carbon steel and alloy steel. b. SS-304: Stainless Steel 304 and 316 belong to stainless steel c. SS-302: Stainless Steel 302: better structural toughness d. Aluminum 5052: Aluminum alloy 5052 d. Brass: Brass e. Bronze: Bronze f . UNS C11000 Copper: Antimony Copper
The embedded nut is made of copper nuts made of various embossed wires (usually lead brass, such as H59, 3604, 3602). The embedded knurled copper nuts that we come into contact with on a daily basis are processed by precision automatic lathes. The reference standard for embedded knurled copper nuts comes from the national standard GB/T809. The main operation method of the anti-loose nut is to inject the embedded knurled copper nut. After heating, it is embedded into the plastic part or directly injected into the mold. If the mold is injection-molded, the melting point of PA/NYLOY/PET is above 200°C , After the embedded nut is hot melted into the plastic part, the temperature rises rapidly. After injection molding, the plastic body rapidly cools and crystallizes and becomes hard. If the embedded nut temperature is still at a high temperature, it may fall to the place where the copper nut contacts the plastic part. Start to loosen or crack. Therefore, copper nuts are used instead of carbon steel nuts in the injection molding of embedded nuts. There are two ways to form the external knurling of the embedded copper nut. One is to use copper raw material to draw the knurl and then to produce it on the upper equipment. Generally, the pattern of this method is straight, and the other is to use The round copper material is directly embossed while tapping during the production process. This processing method can produce some non-standard size knurled copper nuts. The embossed shape of the embedded copper nut can be selected by the user, such as mesh, Character embossing, herringbone embossing and other knurling patterns.
Due to manufacturing and installation errors, the lamp head and its connecting part of the shadowless lamp will drift, which cannot be positioned at any position. Therefore, in the shadowless lamp, the damping force is usually provided by the damping screw to realize the positioning of the lamp cap and its connecting part. The damping screw needs to be able to provide a suitable damping force. The damping force should not be too small to meet the positioning requirements; at the same time, the damping force should not be too large to make the user feel comfortable when moving the lamp head and its connecting parts. In addition, within the normal life range, after the damping screw is worn, it should also be able to provide sufficient damping force to satisfy the positioning of the lamp cap and its connecting part. The damping screw is tightened by the thread, the top pressure disc spring is deformed, and the disc spring presses the friction end to generate frictional force, thereby providing an effective and lasting damping force. The damping force can be realized by adjusting the screw tightness. For the friction ends, there are certain requirements for wear resistance, certain self-lubrication, certain strength, hardness and toughness. At present, the friction end materials in the industry mainly include metals such as brass and tin bronze; non-metals such as nylon and POM. At present, the main disadvantage of the friction end of the damping screw is that it is easy to produce abnormal noise during the friction process for metal materials. For non-metallic materials, deformation is easy to occur and the strength is insufficient.
As we all know, screws and nuts are widely used in various mechanical equipment as connectors, so that the mechanical equipment can be easily disassembled, but for equipment whose internal structure needs to be kept secret, it generally does not need to be disassembled after assembly. The nut can be easily dismantled, leaving equipment that needs to be kept secret of the internal structure from being kept secret.
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