What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Most of the existing screws use an integral metal structure, and there are still some problems, such as large weight, high cost of materials, wear resistance, hardness, rust resistance, corrosion resistance, high and low temperature resistance, brittleness, toughness, etc. Many occasions cannot meet the needs of production, and further improvements are needed to improve production efficiency, reduce costs, improve safety, and prolong the service life of screws.
The main operation method of the embedded knurled copper nut of the lock nut is injection molding. After heating, it is embedded into the plastic part or directly injection molded. If injection molding is used, the melting point of P/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 hardens. 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.
In mechanical devices, there are many ways to install and connect two components, such as bolt connection, welding, etc., but for installation and connection in a narrow space, such as the socket of two hollow cylinders with smaller diameters, due to the relatively small space It is very difficult to use this method, and it is extremely inconvenient to install and connect.
In terms of inner hexagon, there are two versions of the national standard, one is GB70-76, the 76-year version, and the other is GB70-85, the 85-year version, most of which implement the DIN912 standard, so you should pay attention to the difference in actual business operations: GB70 -85 completely coincides with DIN912, so there is no difference in the use of the new standard, mainly the difference between GB70-76 and DIN912: for M8 series hexagonal products, the diameter of the round head of GB70-76 is 12.5MM, It is smaller than 13.27MM of DIN912. For M10 series inner hexagon products, the round head diameter of GB70-76 is 15MM, which is smaller than 16.27 of DIN912. For M12 series inner hexagon, the round head diameter of GB70-76 is 18MM. It is smaller than the opposite side 18.27 of DIN912, and the round head diameter of the inner hexagon GB70-76 of M16 and M20 series is 0.33MM smaller than that of DIN912, which are 24MM and 30MM respectively. DIN912 is 24.33MM and 30.33MM respectively. In addition, the width of the inner hexagon between the old standard and the German standard is different due to different standards. The inner side of GB70-76 is smaller, and it should be paid attention to in business operations.
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