Que es el tornillo

Screws and bolts are similar types of fasteners, usually made of metal, with helical ridges called external threads (external threads). Screws and bolts are used to fasten materials by the engagement of threads with similar internal threads (internal threads) in mating parts.Screws are usually self-threading (also known as self-tapping),and when the screw is turned, the threads cut into the material, creating internal threads that help pull fastened materials together and prevent pulling out. There are many types of screws and a variety of materials; materials commonly screwed include wood, sheet metal, and plastic.

Explanations 

A screw is a combination of simple mechanics: it's essentially a bevel wrapped around a central shaft, but the bevel (thread) also forms a sharp edge on the outside that acts as a wedge when it's pushed into the material being fastened, the shaft And the helix also forms a wedge at that point.Some threads are designed to mate with complementary threads called internal threads (internal threads), usually in the form of nut objects with internal threads.Other threads are designed to cut helical grooves in softer materials when the screw is inserted.The most common uses of screws are to hold objects together and to position objects.Screws usually have a head at one end that can be turned with a tool.Commonly used screwdrivers include screwdrivers and wrenches.The head is usually larger than the body of the screw, which prevents the screw from being driven deeper than the length of the screw and provides a bearing surface.There are exceptions.Carriage bolts have a domed head that is not designed for driving. Set screws can have a head size equal to or smaller than the outside diameter of the screw thread; set screws without a head are sometimes called grub screws.J-bolts have a J-shaped head that sinks into the concrete and acts as an anchor bolt.

The cylindrical portion of the screw from the underside of the head to the tip is called the shank; it may be fully or partially threaded.The distance between each thread is called the pitch. Most screws and bolts are tightened with a clockwise turn, known as right-hand threads.Screws with left-hand threads are used in special cases, such as those where the screw will be subjected to counterclockwise torque, which would cause a right-hand screw to loosen.Therefore, the left pedal of the bicycle has a left-handed thread.