Service HotlineIn CN203807560, nails and bolts are used to connect the plates, but the heads of the nails and the bolts are enlarged ends that are wider than the rods, and the heads of the nails and the bolts cannot penetrate into the interior of the door body, so in terms of appearance, the more More nails and bolts will leave more spots on the surface of the door that are not suitable for the door itself. In the prior art, the treatment method for these spots is generally to paint with paint, which can only make the door panel consistent with the head of the nail and the bolt in color, but cannot change the shape of the head of the nail and the bolt, and the appearance is still good. Obvious spots were noticed, which made the door panels connected by nails and bolts to the panels, which could not be used as door panels for household doors.
In the design of electrical products, in order to avoid the problem of electromagnetic radiation interference, it is necessary to isolate the conduction between metal parts (parts). Especially when the metal parts are locked by metal screws, the conduction between the locked pair of metal parts (parts) is often caused, so it is necessary to try to isolate them. For example, when screws are used to lock the structure iron of the liquid crystal display screen and the iron structure of the foot base, the electromagnetic waves generated by the liquid crystal display screen are easily radiated from the foot base, causing electromagnetic radiation interference.
With the continuous improvement of road facilities, guardrails are set up in the middle of the roads in most cities at the separation of the upper and lower lanes. At the same time, guardrails are also set up between the motor vehicle lane and the non-motor vehicle lane. The bottom of the guardrail column is set with a base, and the base is usually made of If the steel nail is fixed, the deformation hole should be drilled on the asphalt road first, and then the steel nail should be knocked into the deformation hole. Because the outer wall of the steel nail is cylindrical, the friction force on the ground is small, and the guardrail is affected by the deformation. When the external impact force occurs, the steel nails are easily detached from the asphalt road, making the road guardrail lose its fixation. In some places, expansion screws are used to fix the railings, but during the tightening process of the expansion screws, the expansion pieces are opened by the force of the ejector rod, and the opening angle is small. Limited, the railing will still fall down when subjected to a large impact. Therefore, it is necessary to design a special screw for fixing the railing on the asphalt road.
With the popularization of electrical equipment, the door cover that integrates the panel, the controller, the sealing and waterproof function and the appearance decoration has gradually been required for equipment matching. The head directly affects the appearance, and for kitchen equipment such as dishwashers, the fixing screws of the door cover are easily rusted in direct contact with the washing water, which urgently needs a door cover structure that is easy to disassemble but does not affect the appearance.
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.
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