(1) Variable diameter helical springs: These are used in special applications. The material of variable diameter springs is generally circular cross-section, and they mostly bear compressive loads.
(2) Leaf springs: These springs are made of spring strip (or sheet metal), machined using appropriate molds on specialized equipment or general-purpose pressure processing machine tools. Leaf springs, wave springs, and light springs have relatively thin materials, while medium or large disc springs often have thicker materials. These springs have a wide range of applications.
(3) When installation space is limited, springs with rectangular cross-sections are often used because springs made of rectangular cross-sections can achieve a larger load under the same space and the same amount of deformation. Compared with springs with circular cross-sections, these springs have a larger cross-sectional area in the same space, and therefore absorb more energy, as shown in Figure 1. They can be used in heavy machinery, stamping dies, or springs with particularly high stiffness.
(4) Disc springs are small in size and light in weight, widely used in buffering and vibration damping applications, and are commonly used in stamping dies, valve clutch fasteners, and petroleum and geological engineering machinery.
(5) Convex helical compression springs can achieve a large deformation because the smaller coils at both ends can be embedded in the middle coil. For example, some convex automotive brake springs are normally in a compressed state; when the car valve is opened, the spring returns to its original deformation, driving the brake to apply pressure. Hair clippers also utilize this characteristic of convex helical springs to achieve large deformation and stress within a limited space.
(6) Spiral coil springs function similarly to conical coil springs; they absorb a large amount of energy under pressure. Due to manufacturing difficulties, they are only used in special situations where space is limited. Planar spiral coil springs have more coils, resulting in a larger deformation and the ability to store more energy. They are often used in compression springs and energy storage elements in instruments.
(7) Leaf springs can be made from a single leaf spring or multiple leaf springs stacked together. They have good cushioning and vibration damping performance, especially multi-leaf springs, which have strong vibration damping performance. They are mainly used in the suspension systems of automobiles, tractors, and railway vehicles.
(8) Unequal pitch helical springs are mainly used in the suspension springs of motorcycles and small passenger cars, as well as valve springs for high-speed engines. A single spring can simultaneously meet the requirements of low stiffness when deformation is small and high stiffness when deformation is large. Unequal pitch springs perfectly satisfy these special requirements.
(9) A torsion bar spring is essentially a straight rod made of elastic material subjected to torque. It has high deformation energy per unit volume and is mainly used in the suspension systems of various vehicles.
(10) A ring spring consists of an outer ring with an inner conical surface and an inner ring with an outer conical surface. The number of rings depends on the magnitude of the load and the deformation requirements. Ring springs have high vibration damping capacity and are mainly used in heavy equipment and buffer devices.
(11) Wire springs are various linear springs made from spring wire, generally cold-drawn spring steel wire. Wire springs are mostly used in applications with small loads and no strict requirements on load characteristics. The cross-section of a wire spring is often circular, so its load has no directional limitation and it has the same bending stiffness in all directions.
(12) Spring retainers are available in both round and rectangular cross-section materials. Sometimes, for ease of assembly, the retainer is made with a bent end. When manufacturing retainers, the tightly wound spring coil can be cut off and flattened on its own; however, a large initial stress is required during winding.
(13) Snake springs are named for their snake-like shape and are also called "Z"-shaped and "S"-shaped springs. They are widely used in car seat cushions and are therefore also called seat springs.
(14) Multi-strand helical springs are generally made by first twisting 0.5mm~3mm steel wire into a cable, and then coiling it into a spring. The most common type is a 3~4 strand cable without a center strand. When the cable has more than 4 strands, a center strand should be included. To prevent the cable from loosening under stress, the direction of the cable's rotation should be opposite to the direction of the spring's rotation.
(15) Clamp springs are commonly used for fastening automotive fluid reservoirs, etc., and belong to the category of double torsion springs. These springs can be rolled using CNC spring coiling machines in companies with the necessary resources, but most companies roll them manually. Specialized auxiliary tools can be made during the rolling process. First, the coiled material is cut and straightened, then shaped into a "U" shape, and finally bent onto a specialized auxiliary tool. This tool can be used with a spring coiling machine that uses a sector gear feeder. By utilizing the reciprocating feeding mechanism of the spring coiling machine, the tool "b" is mounted on the feeding guide wheel, thus achieving semi-automated production of bent clamp springs, increasing production efficiency by about 10 times compared to manual operation.
