How many types of compression springs

Compression springs store mechanical energy when compressed and release mechanical energy when the load is removed. Although compression springs are generally made of spring steel, they may also contain carbon, magnesium, nickel, chromium, tin, copper, tungsten, and aluminum.

Different materials create varying degrees of elasticity and energy storage capacity for compression springs.

Robert Hooke proposed a formula as early as 1676 to calculate the force exerted by a spring, which is proportional to its elongation.

Compression springs are mechanical devices specifically designed to sense axial compressive loads. They can usually also stretch and rotate to a point. Generally speaking, compression springs can store mechanical energy when subjected to compressive loads. Once the load is removed, they will return to their original shape and size - undergoing elastic deformation.

This unique ability to store potential energy, combined with its relative simplicity and affordability, makes compression springs valuable in a wide range of applications. From mechanical keyboard buttons, mattresses and ballpoint pens, to firearms and car suspension shock absorbers. Since the 15th century, we have been using compression springs, and the first compression spring was used in clock devices.

Types of compression springs

Compression springs can have many different geometric shapes. The most common ones are coils or spiral springs. This shape is more popular than other shapes because it allows for seamless high compression and expansion to a point. It is also lighter because it uses fewer materials to meet the need for absorbing compressive loads. Finally, the shape of the coil spring gives this type a relatively large spring constant (which will be explained in detail later).

This category is further divided into subcategories, including:

Material of compression spring

Compression springs are usually made of spring steel, which is a type of steel with high yield strength. This allows them to maintain their original shape, size, and shape even when deformed to the extreme. Therefore, these steels have a large elastic deformation space under stress. This happens at the molecular level, so the composition of these steels has a significant impact on their elasticity.

Generally speaking, spring steel contains carbon and manganese, as well as nickel, chromium, molybdenum, tin, vanadium, copper, iron, tungsten, and aluminum. Spring steel is classified by the official ASTM based on its yield strength and hardness, so different material compositions can be suitable for different applications. For example, ASTM A228 is used for piano strings, containing 0.7% -1% carbon and 0.2% -0.6% manganese, with a maximum yield strength of 530 megapascals and a tensile strength of 400 megapascals.

Characteristics of compression springs

In this section, I will focus on introducing uncoiled coil springs, as these springs are the most widely used compression springs. These springs have certain characteristics that have great significance for their performance. The outer diameter (D) refers to the diameter of the cylinder formed by the spring when viewed from the top. The coil diameter refers to the thickness (d) of the spring wire, which is also cylindrical. The free length (L) refers to the total length of the spring without any compression, while the effective helix (na) and total helix (n) are the number of coils that store and release mechanical energy, and the number of bus coils (at least two are dedicated to the end/base of the spring). Another important morphological attribute is the direction of rotation, which can be left or right.

The force exerted by a spring is proportional to its elongation, a law proposed by Robert Hooke in 1676, within a few short years of the first spring's application. Hooke introduced this formula to the world. "F=- kx", where F is the spring force, x is the stretching distance, and k is the spring constant. Each spring is different and determined by the manufacturer through experiments or by the user through formulas. K=Gd4/[83dna]. As mentioned earlier, barrel and conical coils are nonlinear springs, so Hooke's law does not apply to them. Hooke's law does not apply to springs that have already deformed or exceeded the general elastic limit.

The force of a fully compressed spring

To calculate the force of the fully compressed spring, we can use this formula. Fmax=Ed4 (L-nd)/[16 (1)+ ν) (D-d) 3n]. E is the Young's modulus, d is the diameter of the steel wire, L is the free length, and n is the number of effective helices/coils, ν It's the Poisson's ratio, and D is the outer diameter. It is obvious that some of them are determined by the steel chosen by the designer, while others are determined by the form, shape, and size of the spring.

Design considerations

When designing a compression spring, the first thing to decide is what material you want to use. Then find the shear modulus (G) and tensile strength (TS) from the data table. These two factors are crucial for determining the percentage of stress, for example, when calculating load requirements (100* σ/ Calculate the degree to which the spring is compressed when a certain load is induced, based on the tensile strength.

Another important consideration is the diameter of the spring when compressed to its maximum point. Spiral compression springs tend to increase in diameter during compression. So it is important to calculate this expansion using the formula "expansion={sz [(D-d) 2+(p2-d2/π 2)+d] - D}".

The index of the spring is important, and designers attempt to maintain it within the range of 4 to 10. Its calculation method is "C=(D-d/d)", which provides a good concept of the ratio of wire thickness to spring diameter. This will determine the overall strength of the spring (smaller is stronger, but larger is easier to compress).