What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
In the fastening connection parts and parts assembly of various equipment and tooling, if the screw and nut anti-loosening treatment is required, there is a contradiction between anti-loosening and tightening or tightening and loosening. For example, the resistance is large when tightening. , or the resistance is large when loosening, or the anti-loosening effect is not good, or the service life is short, and it will be scrapped after 2 to 3 times of use. In a word, all kinds of anti-loosening nuts have the above problems at present. Therefore, it is necessary to utilise a new type of anti-loosening nut with low resistance when tightening or loosening, but with better anti-loosening effect and long service life.
The material of the rubber gasket is NBR nitrile rubber, which is the most commonly used and has the highest cost performance. The use of FFKM perfluoroelastomer gaskets is generally in the more advanced fields, such as the field of aerospace rockets. Because its price is quite expensive, but its performance is excellent and can exceed many metal materials. For specific material information, please refer to the following: Material Name Chemical Description English Abbreviation English Alias Nitrile Butadiene Rubber Acrylonitrile-Butadiene Rubber Ethylene-Propylene-Diene Rubber EPDM EP,EPT,EPR Neoprene Neoprene CR Neoprene Silicone Silicone Rubber WMQ PVMQ Fluorosilicone Fluorosilicone Rubber FVMQ FVMQ Acrylate Acrylate Rubber ACM ACM Ethylene Acrylate Vinyl -Acrylic Rubber AEM Vamac Styrene-Butadiene Styrene-Butadiene Rubber SBR SBR Polyurethane Polyester/Polyether Urethane AU/Eu AU/EU Natural Rubber Natural Rubber NR NR
Screw model Drive Code: groove on the head, characteristic model Length Code: screw length (mm) A-1: Thread Code: screw model Metric screws directly indicate the screw model with the outer diameter of the screw, such as M3, the outer diameter of the screw is 3.00mm. ; M4 means the outer diameter of the screw is 4.00mm. Metric Thread Size x Pitch: Note: The metric screw is behind the screw model, and sometimes the screw pitch is indicated. Such as M3x0.5, M4x0.70, M5x0.8, M6x1. Standard specification, usually not mentioned. A-2: Length Code: Screw length: For metric screws, the screw length is directly marked in mm. The total length of the screw is marked, only the length below the head is calculated, excluding the head height. But With the exception of flat head screws, the total length of the screw is marked with the head height. A-3: Drive Code/ Head Groove, Features.
In the prior art, the screw suction device can be implemented in the following two ways. One is to use a magnet to magnetize the electric bit head, and the electric bit head is used to approach the screw, and the screw is stuck by the electric bit head, so that the function of picking up the screw can be realized; The vacuum generator is used to form a negative pressure in the screw guide groove, and the screw is sucked into the tube to realize the screw pickup. The disadvantage of this solution is that in the process of picking up the screws, the grooves of the screws cannot be aligned, which leads to the deviation or leakage of the screws. The disadvantage of this solution is that the screw with an aspect ratio of less than 1.8 is prone to suction and skew, and the stability is not high. It can be seen that the existing technology still needs to be improved and developed.
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