Screws

A screw is a tool that uses the physical and mathematical principles of the circular rotation of the inclined plane of the object and the friction force to tighten the mechanism of the object step by step.  A screw is a general term for a fastener, an everyday word.  Screws are indispensable industrial necessities in daily life: such as cameras, glasses, clocks and watches, electronic use of extremely small screws;  General screws for televisions, electrical products, Musical Instruments, furniture, etc.  As for engineering, construction, bridge use large screws, Nuts;  Transportation equipment, aircraft, trams, cars and other screws for the size and use.  Screws have important tasks in industry. As long as there is industry on the 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 big invention of human beings.