What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
M4 grounding screw used to fix the grounding wire on household appliances and other equipment, the stud is cylindrical, and the thread is perpendicular to the end (section) surface. However, the screw holes on the equipment all have tapping guide grooves for sinking and guiding due to the manufacturing process requirements. When fixing the ground wire, if the screw is not positioned accurately (the screw is inclined), the screw is pressed down hard, which is easy to cause the screw and the screw. The screw hole bites the teeth, and after biting the teeth, it is easy to cause the screw to loosen or fall off, posing a safety hazard.
The purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to overcome the above-mentioned shortcomings of the prior art, and provide a hidden screw fastener, which avoids the defect that the screw end cap is directly exposed when the traditional screw is tightened, which affects the appearance. Washers and shields hide the end caps of the screws, which are both beautiful and insulating, preventing the screws from rusting, and avoiding scratches due to burrs on the ends of the screws, which are not only beautiful but also practical and safe.
rivet dismantling method and a dismantling device thereof. The dismantling method firstly places a riveting piece with a failed rivet installed on a die having a blanking hole, and then uses a punch that coincides with the center line of the rivet on the riveting piece to impact the rivet. , the rivet falls into the blanking hole under the impact of the punch to complete the disassembly; the dismantling device includes a concave die for positioning and supporting the riveting piece installed with the failed rivet, and the concave die is provided with a blanking hole; The upper part of the die is provided with a punch for punching the rivet into the blanking hole, and the punch and the center line of the rivet are coincident; Yueluo adopts the punch to dismantle the failed rivet, which not only has high work efficiency, but also has high work strength. It is small, and does not damage the riveting parts on which the rivets are installed; the impact process will not cause the rivets to splash, and the safety is high; and the cost of dismantling equipment is low.
In many national standards, there will be a division of intensity levels. Combination screws are no exception. The strength grade of the combined screw is divided according to the material of the screw wire and the hardness index of the screw wire. General combination screw materials are divided into stainless steel and iron, stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316 and so on. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel. Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9, and 12.9. However, the combination screws of grade 10.9 and grade 12.9 are rarely used in the market, so we will not talk about them here. And the combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8. 4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8. 8.8 grade combination screws are generally made of screw wire 10B21 piers. After the screw and wire piers are made into screws, they are equipped with spring washers and flat washers. They can pass through the automatic elastic flat washer machine to rub the three pieces together. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to prevent hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, we have to perform hydrogen removal treatment on the hardened combined screws, and only after the hydrogen removal can be plated. In short, there are many kinds of standard grades of combined screw strength, but generally only two types are used in the market, one is the 4.8-level combined screw strength, and the other is the 8.8-level combined screw strength. 4.8-level combination screws are the most used in the market and customer needs, and have a wide range of applications. As for the standard strength of 8.8-level combination screws, we generally refer to 8.8-level hexagon socket head combination screws, 8.8-level pan head combination screws, and 8.8-level external hexagon combination screws. These three are more commonly used.
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