What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The rubber ring and the metal ring are integrally bonded and vulcanized. It is a sealing ring used to seal the thread and flange connection. The ring includes a metal ring and a rubber gasket. The metal ring is rust-proof, and the rubber ring is generally made of oil-resistant nitrile rubber or fluororubber. Combination pads are available in metric and inch sizes, and the standard JB982-77 specifies the combination of metal pads and rubber. Combination sealing washer is used for threaded pipe joints and screw plug sealing. It is generally used with ferrule type pipe joints to block oil ports. It is mainly used for end face static sealing of threaded joints of hydraulic valve pipe joints. It is suitable for British and American standards. Inch thread and end face static seal at French and German standard metric thread connections, etc. The combined sealing gasket can be divided into A type and B type according to the structure; it can be divided into full package and half package according to the difference of rubber.
The locking effect of the spring washer is general, and the important parts are used as little or not as possible, and the self-locking structure is adopted. For spring washers used for high-speed tightening (pneumatic or electric), it is best to use surface phosphating washers to improve their anti-wear performance, otherwise it is easy to burn out or open mouth due to friction and heat, and even damage the surface of the connected parts. For thin plate joints, spring washer construction should not be used. According to statistics, spring washers are used less and less in automobiles.
The rivet nut is a kind of nut applied to thin plate or sheet metal. The principle is to press the embossed teeth into the preset holes of the sheet metal. Generally, the diameter of the square preset holes is slightly smaller than the embossed teeth of the pressure riveting nut. The periphery of the hole is plastically deformed, and the deformed object is squeezed into the guide groove, thereby producing a locking effect. The pressure riveting nut is divided into free-cutting steel pressure riveting nut S type, stainless steel pressure riveting nut type CLS, stainless iron pressure riveting nut SP type and copper and aluminum pressure riveting nut CLA type, which should be used in different environments. . Generally speaking, the national standard domestic products without rivet nuts from M2 to M12 are PEM specifications, which are usually produced in chassis cabinets and sheet metal industries.
The existing machine screw structure is not conducive to assembly and automated production. The machine screw is in the form of a cylinder, the outer surface of the cylinder is provided with threads, and one end of the machine screw is provided with a notch. During installation, it is convenient to rotate the machine screw by the tool acting on the notch, so that the machine screw all enters the threaded hole and does not occupy the external space. However, the thread on the outer surface of the machine screw corresponding to the slot is easily deformed or scratched due to the external force of the tool and the threaded hole, which makes it difficult to screw in or disassemble, and reduces the versatility and interchangeability. affect product quality.
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