Most materials have different degrees of elasticity. If they are bent, they will be restored to their original shape with great force. In human history, it must have been noticed for a long time that the branches of saplings and saplings had great flexibility, because many primitive cultures used this feature to wedge a stick behind a special door or cage, or to pull down a rod with a loose knot; once the tension was released, the stick or rod would rebound. They use this method to catch animals and birds. In fact, bows use the elastic springs of young trees in this way; first pull the bow back, and then let it spring back. In the middle ages, this idea began to appear in machinery, such as textile machines, lathes, drills, grinders and saws. The operator uses his hand or pedal to give the down stroke and pull down the working machine. At this time, a rod fixed on the machine with a rope rebounds to produce reciprocating motion.
The torsion resistance of elastic material is not equal to its flexibility. In the period of the Greek Empire (about the 4th century B.C.), a torsion spring was invented to strengthen the power of crossbows and stone throwers with twisted tendon or wool ropes instead of simple springs. At this time, people began to realize that metals are more elastic than wood, cutin or any of these organic substances. Philo (who wrote about 200 BC) introduced it as a new discovery. He estimated that the readers were incredible. The flexibility of the Celtic and Spanish swords attracted the attention of his predecessors in Alexandria. In order to find out why the sword is elastic, they carried out many experiments. As a result, his master, courtesie, invented the riprap machines, whose springs were made of curved bronze plates – in fact, the earliest leaf springs; Philo himself further improved them. After the invention of this kind of riprap machine, the creative katesi came up with another kind of riprap machine – it uses the elastic work produced by the air in the cylinder under pressure.
It was not until a long time later that people thought that if a screw rod was compressed instead of a straight rod, the energy stored in the metal spring would be greater. According to his biography, he made an alarm clock, in which several generations of springs were used. It has recently been pointed out that this alarm clock was included in a mechanical manual at the end of the 15th century with some peculiar spiral spring watches and clocks. These springs are also used in modern mousetrap. Clocks with coil springs (horizontal compression instead of vertical compression) must have been in use around 1460, but they were basically Royal luxury. It took another century for clocks with springs to become the symbol of the middle class.
The main materials for spring production are: high quality carbon steel, alloy steel, nonferrous metal alloy, etc.