Torsion springs are a type of coil spring with the goals of storing rotational energy and/or to apply torque. To assist them in their goal, they are designed to be subjected to rotational, or twisting, force. This contrasts with both extension and compression type springs, which are both instead subject to compressive forces such as squeezing.
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Torsion Spring Design
Typically, torsion springs are made from steel materials only, such as hard drawn steel, steel music wire, stainless steel and spring steel. Note that spring steel is a special kind of steel that is designed to display increased elasticity and return properties. Spring elasticity is an important quality because it is the property that allows a spring to return to its original position. Because stainless steel and some other steel material varieties are corrosion resistant, torsion springs often do not require finishes. However, manufacturers frequently do make the choice to coat springs with finishes such as zinc, passivate, iridite and black oxide because they do protect springs that will come in regular contact with moisture, whether from inclement weather or some other circumstance.
They also offer some protection to torsion springs against gradual destructive forces like wind and large amounts of stored force. Manufacturers can also customize torsion springs to fit the various specifications of different applications, such as tightness of coil winding, spring rate, torque generation (from very weak to very forceful), deflection and load.
Torsion Springs Production Process
To make torsion springs, manufacturers typically begin with a type of roll forming called the cold rolling process. Cold rolling works by putting a metal coil through a roll forming machine, which consists of a series of roller die parts called calendars. The calendars are positioned above and below the metal coil to be formed, and as the metal goes through the machine, they bend the metal on the linear axis. Thus, the metal takes on a more uniform grain flow and shapes into flat coil strips. During this process, the steel material is heated only to temperatures below its point of recrystallization, thus increasing its tensile strength. After a torsion spring has been initially formed, manufacturers put it through secondary processing in order to wind it or coil it.
Depending on the type of steel with which the spring has been made, manufacturers will approach this differently. First, for example, a spring made from spring steel can be annealed, or made softer through heating and worked on while it is more malleable, because spring steel responds very well to heat treatment. On the other hand, because stainless steel cannot tolerate heat treatment, a stainless steel spring cannot be annealed. To wind its coils, manufacturers often turn instead to lathe forming. During lathe forming, a lathe machine winds coils using rapid rotation. After the coils have been wound, a steel spring, if the material allows it, is heat treated in such a way that its stresses and fractures are reduced and the spring as a whole is strengthened.
Applications of Torsion Springs
Torsion springs have many different applications in many different industries, such as electronics, manufacturing, home and garden, office supply and sports and recreation. To fit the needs of these applications, they are available in many different shapes and sizes. Some examples of the applications in which smaller torsion springs are used include: digital cameras, CD players, hinges, mousetraps and clothespins. One of the most common mechanisms in which large torsion springs are used are garage doors.
Things to Consider When Purchasing Torsion Springs
No matter the exact way in which a torsion spring is made, it is vitally important that it is matched with an application that will benefit from its composition. It is dangerous to use torsion springs with applications for which they are not properly equipped, as such misuse could easily lead to sudden and unexpected spring failure. Such failures have the potential to not only interrupt an application, but to also cause damage to property or injury to people in the vicinity. The best way to make sure that you purchase torsion springs that are safe and advantageous for use with your application is to go over your specifications with an experienced spring manufacturer. With them, you can make sure that you get a spring or set of springs with the most appropriate material composition, material finishes, shapes, diameters and coil tightnesses.
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