What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
On the surface of the mounting hole on the connector, a 90-degree conical socket is machined, and the head of the flat machine screw is in the socket and is flush with the surface of the connector. Flat machine screws are also used in some occasions with semi-circle head flat machine screws, which are more beautiful and are used for places where a little protrusion is allowed on the surface. Screws play the role of connecting two or more objects and are an indispensable necessity in daily life or industrial manufacturing. There are countersunk head bolts (with grooves) and countersunk head bolts (with tenon).
Bolt material: 18Cr2Ni4W, 25Cr2MoV steel; bolt specification: M27～M48. Because this kind of steel is easy to form a passivation film on the surface, and this passivation film will make the bolt unable to obtain a good adhesion chemical nickel phosphorus layer, so special pretreatment measures must be taken to remove the film first, and measures should be taken To prevent its regeneration, it is possible to ensure a good bonding force between the plated coating and the substrate. At the same time, due to the large geometric size of the bolt, it increases the difficulty of nickel-phosphorus plating treatment and quality inspection of the process.
Washers are common parts that are annular or annular after compression. The existing standard washers include flat washers, spring washers, serrated lock washers, saddle washers, etc. The end faces are mostly flat or flat after compression. , so it is in surface contact with the workpiece. Generally, after the two workpieces are locked by washers, bolts and nuts, the workpieces cannot move in any direction, so as to achieve the purpose of tightening the two workpieces. In actual production, some workpieces are still required to be properly translated in a certain direction after locking. In order to achieve this requirement, the usual practice is to open a waist-shaped hole on the workpiece that needs to be moved, and the zigzag-shaped bushing is fitted with a flat washer after passing through the waist-shaped hole, as shown in FIG. The edge of the hole is located in the space enclosed by the bushing and the flat washer, and a gap is formed between the workpiece and the bushing and the flat washer, so that even if the bolt passes through the flat washer, the bushing and the workpiece in turn, it is threaded and locked with the nut. tight, the workpiece can still translate along the length of its girdle hole. Obviously, this method can achieve the requirement of proper translation of the workpiece, but the following deficiencies can still be found in the actual assembly. First, before locking, the bushing, washer and workpiece are separated from each other, so it is more inconvenient to assemble; secondly, the lining is The separation structure of the sleeve and the gasket is inconvenient to manage, and the disassembled gasket and bushing are easy to lose and affect the use again.
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.
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