What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Sprinkle the excess flat washer 6 on the positioning plate II3-1 on the flat washer positioning plate 3, and shake the flat washer positioning plate 3 by hand. After a short time, the flat washer 6 will be positioned and arranged on the upper positioning plate II3-1. In the flat washer hole 3-7, since the width of the opening groove 113-32 of the baffle plate II3-3 is smaller than the diameter of the flat washer hole 3-7, and the thickness of the upper positioning plate II3-1 is designed according to the thickness of the flat washer 6, each Only one flat washer 6 can be accommodated in the flat washer holes 3-7 of each upper positioning plate II3-1, and then use a brush to remove the excess flat washer
Screw: A type of fastener consisting of a screw head and a screw rod (a cylinder with an external thread), which needs to be used in conjunction with a nut to fasten and connect two parts with through holes. and widely used in people's lives. In real life, due to the vibration of the machine, the workpiece is loose at the connection between the screw and the nut, and the nut needs to be tightened frequently, which is time-consuming and laborious, delays time, and reduces the production efficiency, so how to reduce the production process. Frequent tightening of screws has become an unsolved problem for people. Therefore, there is an urgent need to provide a slotted screw.
square nut described by Guangdong Yueluo Hardware Industry Co., Ltd. includes a nut body 1, the nut body 1 is in the shape of a cube, the side length is 7.6mm, and the height is 2.4mm. The upper and lower ends of the nut body 1 are respectively set. There are circular protrusions 2 and circular protrusions 3 with a height of 0.25mm, and the circular protrusions 2 and the circular protrusions 3 are respectively tangent to the upper and lower surfaces of the nut body 1 in a square shape. A through hole 4 is provided in the middle of the shaped protrusion 2 and the circular protrusion 3, and runs through the nut body 1. The opening of the through hole 1 is provided with a chamfer 5 of 30°, and a thread 6 is provided on the inner wall of the through hole 4. , the circular protrusion 2 is provided with a number of strip-shaped protrusions 7 along the circumference inward to the opening of the through hole 4. The number of the strip-shaped protrusions 7 can be arbitrary, and the ideal number is 26, and the through hole 4 is open. There are several strip-shaped grooves 8 at the circumference of the circular protrusion 3. The number of strip-shaped grooves 8 can be arbitrary, and the ideal number is 26. The circular protrusions 2 and the circular protrusions 3 There is a chamfer 9 of 15° extending outward to the prism of the nut body 1 . The production of square nuts described by Guangdong Yueluo Hardware Industry Co., Ltd. is basically the same as the traditional nut process. The key point is to use a punching machine to punch out circular protrusions on both ends. High, and the circular protrusion 2 is punched again to make a bar-shaped protrusion 7, and at this time, the height of the circular protrusion 2 is consistent with the plane height of the circular protrusion 3, and the circular protrusion 3 is formed by stamping. groove 8. The contact surface of the nut body 1 is increased by providing circular protrusions 2 and circular protrusions 3 on the upper and lower end surfaces of the nut body 1, and respectively providing a bar-shaped protrusion 7 and a bar-shaped groove 8 at the two circular protrusions. Therefore, the friction between the nut body 1 and the fastener is effectively increased, and a good fastening effect is achieved.
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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