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 4 the material cut out when screwing in the screw can be discharged without any accumulation, the dependent claims reflecting many advantages of further embodiments.
Blind hole installation type rivet is a kind of rivet for single-sided riveting. When riveting, special riveting tools, such as pull riveting, rotary riveting, etc., are required. Blind hole installation type rivets are especially suitable for riveting occasions where it is inconvenient to use ordinary rivets to be riveted from both sides. At present, blind hole type blind rivets mainly include rivet blind rivets and blind blind rivets. Most blind rivets of blind hole type contain a lock ring, through which the core rod is locked into the nail sleeve, and there is a common lock ring. Risks of falling off, insufficient clamping force, etc., and the matching relationship of each sub-part in the processing process must be strictly coordinated to ensure the best installation effect; most of the screw-type blind rivets screw the thread through the driving nut to make the nail body or pipe The body is deformed to form a bulge, and the clamping force and anti-vibration ability after installation are much stronger than that of the rivet type, but there are also many sub-parts to drive the nut, mandrel, nail body, tube body, the processing process and the matching of each sub-part When the thickness of the interlayer is different, the fractured part of the core rod is not flush with the interlayer board. For the installation parts with high flatness requirements, air tools are often required to mill them flat.
In actual use, the rivet rod body 3-2 is passed through the riveting plate 6 and the riveting plate 7, and the rivet dome head 3-1 is placed in the mold cavity 1-1, and the cover mold 2 is driven by the riveting machine to impact the rivet rod body 3-2. Because the center of the cover mold 2 is provided with a cavity 2-1 that matches the shape of the rivet dome 3-3, the end of the rivet rod 3-2 will form the rivet dome 3-3. However, due to the rivet When the riveting machine is impacted and vibrated, a large amount of oxide slag 4 will be generated, and the oxide slag 4 will slide down the surface of the cavity 1-1 to the bottom of the cavity 1-1 and accumulate. At this time, the temperature of the rivet is very high and the plasticity is very good. The hardness is extremely low and it is easy to form. Therefore, the accumulated oxide slag 4 squeezes the surface of the rivet dome 3-1 and the bottom surface of the cavity 1-1 to form pits, and causes wear on the bottom surface of the cavity, not only It affects the riveting quality, riveting strength and appearance quality of the rivet, and also affects the quality of the rivet die, resulting in economic losses.
There are two types of bolt detection: manual and machine. Manual is the most primitive and the most commonly used consistent detection method. In order to minimize the outflow of defective products, general production enterprise personnel inspect the packaged or shipped products by visual means to exclude defective products (defects include tooth damage, mixed materials, rust, etc.).  Another way is automatic machine inspection, mainly magnetic particle inspection. Magnetic particle inspection is to use the interaction between the leakage magnetic field at the defect of the bolt and the magnetic powder, aiming at the difference between the magnetic permeability of the bolts (such as cracks, slag inclusions, mixed materials, etc.) and the magnetic permeability of steel, these materials are discontinuous after magnetization. The magnetic field at the place will be turbulent, and a leakage magnetic field will be generated on the surface of the workpiece where part of the magnetic flux leaks, thereby attracting the magnetic powder to form the magnetic powder accumulation at the defect—magnetic traces. The accumulation of these magnetic powders is observed and explained, and the purpose of rejecting defective products has been achieved.
Screws are often used on objects, such as data storage, to support the objects on a bracket. Since the item will vibrate during operation or when subjected to shock, if the shock is not minimized, the item will be damaged. Therefore, some cushioning elements with cushioning properties are applied to the article. The buffer is fixed to the object by the screw. When the object vibrates, the buffer will reduce the vibration, thereby reducing the damage to the object. However, since the buffer is exposed Therefore, when the object is installed or disassembled, the object is moving relative to the bracket, and the friction between the buffer and the bracket will cause the buffer to move. It is very easy to age, thus greatly reducing its service life. SUMMARY OF THE UTILITY MODEL In view of the above, it is necessary to provide a screw combination that can protect a buffer member with buffer performance to improve its service life. A screw combination includes a screw, an elastic retaining ring and a buffer, the screw includes a nut, a threaded portion and a neck formed between the nut and the threaded portion, the retaining ring It is fixed on the neck of the screw, the buffer is sleeved on the screw, and the screw combination further includes a cover set on the screw, and the cover includes a top and a forming part. In the shielding part of the top, the top is located between the nut and the retaining ring, and is blocked by the nut and the retaining ring so as not to be separated from the screw, and the shielding part covers the The retaining ring and the buffer element are slightly exposed from the shielding part. Compared with the prior art, the screw assembly of Guangdong Yueluo Hardware Industry Co., Ltd. protects the buffer by covering the buffer by the shutter, thereby increasing its service life.
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