What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
A screw can be equipped with only one spring washer or only one flat washer, or it can also only be equipped with a two-piece combination of flower teeth. The national standard number of the combination screw is represented by GB9074. The commonly used cross recessed small pan head three combination screw national standard is GB9074.8. This .8 refers to the small pan head. That is, the size of the head of the pan head screw that is often said. Denoted by letters as PM. Professional combination screw manufacturers, the habitual expression method is three-in-one PM. The commonly used cross recessed large pan head combination screw national standard is GB9074.4. Professionally called large pan head combination screws. Or R head, or B head. That is to say, the head of this combination screw is larger and thicker than the head of the small pan head combination screw. There is also a commonly used external hexagon combination screw, which is a cross external hexagon combination screw. It is often called a socket hexagon combination screw. The national label is GB9074.13.
Bolt and nut fasteners are widely used fasteners, which can be used in mechanical products as well as daily craft industrial products, such as plastic packaging boxes, plastic packaging boxes, paper packaging boxes, paper packaging boxes, etc. . When bolt and nut fasteners are used in daily craft industrial products, the requirements for the degree of tightening are generally low, but they are required to be easy to install and use. When assembling the existing bolt and nut fasteners, it is generally necessary to manually twist the bolt or the nut several times until the two are tightened, which takes time and causes inconvenience in daily life. Lower, it is manifested as an increase in labor costs. SUMMARY OF THE INVENTION The main purpose of Guangdong Yueluo Hardware Industry Co., Ltd. is to provide a bolt and nut fastener that is easy to install in view of the above-mentioned deficiencies of the prior art. The two are assembled and fastened, which is convenient to use.
The existing machine screw structure is not conducive to assembly and automated production. The machine screw is in the form of a cylinder, the outer surface of the cylinder is provided with threads, and one end of the machine screw is provided with a notch. During installation, it is convenient to rotate the machine screw by the tool acting on the notch, so that the machine screw all enters the threaded hole and does not occupy the external space. However, the thread on the outer surface of the machine screw corresponding to the slot is easily deformed or scratched due to the external force of the tool and the threaded hole, which makes it difficult to screw in or disassemble, and reduces the versatility and interchangeability. affect product quality.
The working principle of the nut is to use the friction between the nut and the bolt for self-locking. However, the reliability of this self-locking is reduced under dynamic loads. In some important occasions, we will take some anti-loosening measures to ensure the reliability of the nut locking. Among them, the use of lock nuts is one of the anti-loosening measures. There are also two types of locking nuts. One is to use two identical nuts to screw on the same bolt, and a tightening torque is added between the two nuts to make the bolt connection reliable. The other is a special lock nut, which needs to be used together with a lock washer. As shown in FIG. 1, a plastic gasket 2 is arranged in the center of the nut 1 to play a locking effect, but the process is complicated and the production is inconvenient. One is to drill through threaded holes from the outer surface of the nut to the inner thread surface (usually 2, distributed at 90 on the outer surface), which are used to screw in small-diameter countersunk head screws. The purpose is to apply a thread to the thread. A centripetal force prevents the lock nut from loosening. At present, the lock nut with better quality on the market is inlaid with small copper pieces that are consistent with the thread of the lock nut on the inner surface of the nut, which is used to prevent the radial jacking screw from directly contacting the locked thread and being damaged. By. This kind of lock nut is gradually applied in the shaft end locking of rotating motion parts, such as the anti-looseness of the bearing at the mounting end of the ball screw. The process is equally complex.
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