What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
For achieving the above purpose, Guangdong Yueluo Hardware Industry Co., Ltd. provides the following technical solutions: a pin, comprising a pin cap and a described pin rod, the pin cap and one end of the pin rod are fixedly connected, and the pin rod There is a convex body, the convex body is fixedly connected with the pin rod, the convex body is located on the pin rod rod body, and the other end of the pin rod is provided with a top connecting body, and the top connecting body is fixedly connected with the pin rod , the top contact body includes several top contact units and discs, each top contact unit is coaxially arranged with the pin rod, the top contact units are sequentially fixedly connected along the axis direction of the pin, the top contact unit is The major diameter of the outer contour of the connecting body is larger than the diameter of the pin rod.
In each maintenance, the newly replaced stud bolts and other accessories should be inspected. During the inspection, the focus should be on the head and guide part of the stud bolt. It is also necessary to strictly check that each part of the thread has No cracks or dents, also check the tooth shape of the studs for changes. Is there any abnormality in the thread pitch? If there is any abnormality, it must not be used again. A torque wrench should be used when installing the connecting rod cover. It must be tightened according to the specified standards, the torque should not be too large or too small, and attention should be paid to selecting the stud bolts and studs of the supporting manufacturer.
At present, the connecting shafts of commonly used food processing knives on the market generally use square bayonet, which is not easy to install parts, and it is time-consuming and laborious when replacing parts; Increased processing costs. There is also a link structure with a circular bayonet on the market, but it is easy to loosen and not firm after the entire food processor is used for a period of time, which affects the use of the machine. Therefore, a connection structure that is easy to operate and simple to process is urgently needed.
Material and process requirements The self-tapping locking screw should be made of high-quality carburized steel cold heading, generally no larger than M12. The finished material should be drawn with a high total reduction rate before cold heading, so that the cold heading must be spheroidized. Annealing, in order to enhance the surface hardness and the toughness of the core, most of them are made of medium and low carbon steel. The chemical composition of the material in the standard is only for guidance. The C content is 0.13%~0.37%, the Mn content is 0.64%~1.71%, and the B content can reach 0.005%. The elements of S, P, Mn and Si in the commonly used steel are generally lower than those of the ordinary bolt steel of the same grade. And the surface quality of the material is strictly controlled to reduce deformation resistance and prevent deformation and cracking. Commonly used grades are 20Mn, 15MnB, SWRCH22A, 1022A and medium carbon steel, medium carbon alloy steel SWRCH35K, SCM435, SCR435, etc. Self-tapping locking screws are threads with an arc-shaped triangular cross-section, so the formulation of cold heading and wire rolling processes, as well as the design and manufacture of cold heading dies and special rolling plates are very important. Self-tapping locking screws require a high-hard surface for cutting and extruding capabilities due to the need for self-tapping low carbon steel. At the same time, there must be sufficient core strength and toughness to prevent twisting and breaking during work. The heat treatment process of this type of screw belongs to shallow carburizing. Regardless of whether it is made of low carbon steel or medium carbon or medium carbon alloy steel, its core hardness must be guaranteed to be within the range of 28~38HRC (9.8 grade) 33~39HRC (10.9 grade) and not less than the minimum tensile load of 930MPa (9.8 grade), 1040MPa (grade 10.9), depending on the material, the minimum tempering temperature is 420℃. In order to ensure that the self-tapping locking screw can be smoothly screwed into the prefabricated cylindrical hole, the end of the screw should be hardened by high-frequency quenching to ensure that at least one to three thread teeth are hardened, and the minimum surface hardness is 45HRC.
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