A tool for fastening mechanical parts

The screw is a tool that uses the physical and mathematical principles of circular rotation and friction of the inclined plane of the object to tighten the object gradually. Screw is a common term for fasteners, everyday slang. Screws are indispensable industrial necessities in daily life: such as cameras, glasses, clocks, electronics and other small screws; General screws for television, electrical products, Musical Instruments, furniture, etc.; As for engineering, construction, Bridges use large screws, nuts; Transportation appliances, airplanes, trams, cars, and so on, are large and small screws. Screws have an important task in industry, as long as there is industry on earth, the function of screws is always important. Screw is a common invention in people's production and life for thousands of years. According to the application field, it is the first invention of human beings.