What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The quick-install and quick-release nut uses the threaded block to move radially and axially along the inclined surface at the same time to achieve the cohesion and separation of the threaded block. However, the nut has a complex structure and is difficult to manufacture, and the internal and external threads may not be properly locked during use. Occurs, bearing capacity and reliability are poor.
Countersunk head screws are mostly used after installation, and the surface of the parts cannot be raised, and the parts to be fastened have two thicknesses. Thickness, after the screw is tightened, there is still a part of the screw thread that does not enter the threaded hole. In this case, the countersunk head screw can definitely be tightened. There is usually a situation where the thickness of the fastened part is less than the height of the head of the countersunk head screw, which is commonly seen in sheet metal parts in mechanical equipment, such as the connection between the hinge of the chassis and the door and the box; the sheet metal of the equipment The connection of the cover to the equipment, etc. Due to the small thickness of the part, the tightened sheet metal part, the screw through hole completely becomes a conical hole, in this case, when the countersunk head screw is tightened, the screw head is not a tapered surface to press the sheet metal part , but the bottom of the screw head and the top of the threaded hole are squeezed. Although it feels that the screw is tightened, the sheet metal part is stuck instead of being pressed. In this case, although it feels that the screw is tightened, the sheet metal The gold pieces were indeed not tightened. This is a very common situation. Let’s talk about the reasons for the processing: the head cone of the countersunk screw has a 90° conical angle, and the apex angle of the newly bought drill is usually 118°-120°. Some workers who lack training do not know this angle is poor. It is often used to ream the hole with a 120° drill bit, which results in that when the countersunk head screw is tightened, it is not the conical surface of the head, but a line at the bottom of the screw head, which is one of the reasons why the so-called countersunk head screw cannot be tightened. , it's not the screw's fault.
Applications Automotive industry -- cars, trucks, buses, compressors, construction machinery, wind power equipment, fasteners, fasteners, agricultural machinery, foundry industry, drilling equipment, shipbuilding industry, military mining equipment, oil drilling rigs (onshore or offshore), public utilities, rail transit drives System metallurgical equipment rock hammer
A pull rivet, this kind of pull rivet has good installation performance, firm connection and long service life, but the defects are: first, after installation and use, if it is damaged, it cannot be reused; second, it is convenient to disassemble, and it also increases the possibility of theft ,. It is not conducive to safety; 3. There is still the possibility of movement in the circumferential direction of the collar, which will affect the riveting effect.
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