What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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 13 the material cut out when screwing in the screw can be discharged without any accumulation, the dependent claims reflecting many advantages of further embodiments.
GBT 3098.19-2004 blind rivets in my country are divided into: GB/T12615 closed oblate head blind rivets; GB/T12616 closed countersunk head blind rivets; GB/T 12617 open type countersunk head blind rivets; T 12618 Open-type oblate head blind rivets; the international standard is DIN7337; there are 1990 versions and 2004. The 2006 version is mainly the 2006 version.
At present, the convex washers with traditional structures on the market have unreasonable designs and complex structures, and are inconvenient to install and disassemble. After long-term use, they are prone to fracture and deformation due to poor toughness, resulting in short service life and requiring regular downtime for maintenance, affecting assembly. The working efficiency and safety of its equipment are also poor in terms of wear resistance, corrosion resistance, and high temperature resistance. Regular replacement and maintenance also increase the economic cost of production. Therefore, the convex gasket of the existing structure can no longer meet the existing mechanical requirements. The high standard use requirements of assembly auxiliary parts are urgently needed to be solved at present.
In the existing industrial technology field, screws are mostly used for the connection between components. For many electronic products, because the products are more and more thin and light, the connection between the shell and the shell is often affected by the thickness of the shell. , usually need to use screw column structure for connection. Take the existing outdoor three-proof mobile phone as an example: the screw column structure includes a shell, a shell and a screw, the shell is provided with a plurality of screw columns, and the nuts in the screw columns are injected through the in-mold injection process. Directly integrated with the housing. Due to the special use environment and use requirements of outdoor three-proof mobile phones, they need to have good high-strength anti-drop performance, while the three-proof mobile phones in the prior art are subjected to high-strength drop tests due to the fundamental stress concentration of the screw column. During the process, problems such as cracking of the screw column or breaking from the root occur.
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