What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In all kinds of machines and equipment, the various parts are fixed and assembled by bolts and nuts. However, after the machine and equipment are used for a period of time, the bolts and nuts will become loose, which will bring great safety hazards to the use of the machine and equipment. For this reason, when bolts and nuts are used for connection, a spring washer is installed between the nut and the connected part. The spring washer is in the shape of a circular ring, and the ring is not closed, and is sleeved on the bolt. The addition of the spring washer has a certain anti-loosening effect, but it can only prevent the nut from rotating relative to the bolt. In the case of large vibration of the machine, the bolt will rotate relative to the connected part.
When the iron pot is manufactured, the iron head is connected to the iron pot body through rivets, and then the pot handle is set through the iron head, and the iron head connects the pot handle and the iron pot body together. However, when the iron head is installed, the position may be inaccurate. At this time, it is necessary to remove the rivet and reinstall the iron head. At present, the removal of rivets is completely done manually, that is, workers use screwdrivers to unscrew the rivets, which is difficult to remove, wastes a lot of manpower, and has low work efficiency, thereby reducing production efficiency.
rivet with a simple structure includes a rivet cap, a rivet main rod, a rivet limit rod and a limit hole. The rivet main rod is provided with a limit hole inside, the rivet limit rod is located below the rivet main rod, the upper end side of the rivet limit rod is provided with a limit groove, the limit groove is connected with the lower end of the rivet main rod, and the groove surface of the limit groove is round. arc-shaped, the lower end side of the rivet limit rod is provided with four limit grooves, the cross section of the limit groove is in the shape of a right-angled trapezoid, the limit hole passes through the interior of the rivet limit rod and the rivet main rod, and one end of the limit hole The hole surface and the lower end surface of the rivet limit rod are on the same plane.
Although there are many types of self-tapping screws, they all have the following common points: (1) They are generally made of carburized steel (accounting for 99% of the total output). Also available in stainless steel or non-ferrous metals. (2) The product must be heat treated. Carbon steel self-tapping screws must be carburized, and stainless steel self-tapping screws must be solution hardened. In order to make the self-tapping screw meet the mechanical properties and performance required by the standard. (3) The product has high surface hardness and good core toughness. That is, inner softness and outer rigidity. This is a major feature of the performance requirements of self-tapping screws. If the surface hardness is low, it cannot be screwed into the matrix; if the toughness of the core is poor, it will break as soon as it is screwed, and it cannot be used. Therefore, inner soft outer steel is a very important requirement for self-tapping screws to meet the performance requirements. (4) The surface of the product needs surface protection treatment, generally electroplating treatment. The surface of some products must be treated with phosphate (phosphating), such as wallboard self-tapping screws are mostly phosphated. (5) Produced by cold heading process. It is recommended to use high-speed cold heading machine and high-speed thread rolling machine or high-speed planetary thread rolling machine for production. The emphasis here is on high speed to ensure product quality. Only self-tapping screws produced by high-speed machines have well-formed heads and high-quality threads.
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