What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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
As a commonly used data communication device, connectors are widely used in computers and TVs. Because common connectors such as D-SUB and DVI are composed of a male seat and a female seat, the iron shell of the male seat and the female seat is The corresponding position is provided with holes, the holes of the male seat are connected with rivets, and the holes of the female seat are correspondingly provided with screws for fixing. After the male seat and the female seat are connected, tighten the screws so that the male seat and the female seat are tightly connected together. When assembling on a computer or a TV, the rivet has a fixed assembly direction, and the fixation of the rivet direction is very important for assembly. However, there is no anti-rotation device on the iron shell hole connected with the rivet on the existing connector, and the rivet cannot be positioned during the assembly process, and it is easy to rotate and dislocate. production efficiency.
Yueluo relates to a self-tapping screw according to the preamble of claim 1. A self-tapping screw is known from EP0623759B1, the ratio of the outer diameter to the smaller diameter of the self-tapping screw is about 1.25-1.5, the ratio of the outer diameter to the pitch lead is about 1.5-1.6 and the thread The flank angles of , are < 50° and ≥ 35°. EP0433484B1 proposes a self-tapping screw whose thread is provided with cutting teeth of approximately arcuate design, and the cutting edge and the thread crest are at the same horizontal position and are set in opposite directions. One purpose of Yueluo is to realize a general type of self-tapping screw so that it can be screwed particularly easily into holes drilled in concrete or other materials such as bricks and the like. According to Yueluo, this object is achieved by the features in the characterizing part of claim 1, and surprisingly, it has been found that the parallel arrangement of the flanks, ie with a flank angle of about 0°, will make screwing particularly easy when screwing in , especially if the diameter of the hole varies within an allowable tolerance. One reason may be due to the fact that there is no lateral pressure on the material screwed into the thread, even if threads of different depths are cut in concrete or other materials such as brick, chipped plywood, or hardwood. The thread cuts into the material over its entire width by cutting grooves. In particular according to the embodiment of claim 11 the result is that the material cut out when screwing in the screw can be discharged without any accumulation, the dependent claims reflecting many advantages of further embodiments.
In the current plastic matrix, it is common to use self-tapping screws or add copper inserts during injection molding. The former has poor strength, and the threaded hole is easy to crack; the processing cost is high, the injection molding efficiency is low, the labor cost and manufacturing cost are increased, and the insert is easy to slip and crack on the plastic, and the thread strength of the copper insert is not as high as that of the iron nut.
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