What is the force of the extension spring
The calculation formula of compression spring force is as follows:
extended data
related situation of compression spring force
the essence of compression spring force is intermolecular force. The specific situation is as follows:
1. When the object is stretched or compressed, the distance between molecules will change, making the relative position between molecules open or close
In this way, the attraction and repulsion between molecules will not be balanced, and there is a tendency of attraction or repulsion The total effect of attraction or repulsion between these molecules is the macroscopic observed elasticity If the external force is too large and the distance between molecules is too much, the molecules will slide into another stable position Even if the external force is removed, it can not return to the recovery position, and permanent deformation will be retainedbesides the spring size, it is more necessary to calculate the load of maximum load and displacement size; Spring constant: expressed by K, when the spring is compressed, the load (kgf / mm) for every 1 mm distance increase; Spring constant formula (unit: kgf / mm): k = (g) × d4)／8 × Dm3 × NC)
G = steel molus of wire rod: piano wire g = 8000; Stainless steel wire g = 7300; Phosphor bronze line g = 4500; Brass wire g = 3500 d = wire diameter do = od = outer diameter Di = id = inner diameter DM = MD = pitch diameter do-d n = total number of turns NC = effective number of turns = n-2
calculation example of spring constant: wire diameter = 2.0 mm, outer diameter = 22 mm, total number of turns = 5.5, steel wire material = piano wire
k = (G × d4)／8 × Dm3 × Nc＝8000 × 24／8 × two hundred and three × 3．5＝0．571kgf／mm
K=(G × d4)／8 × Dm3 × Nc＝8000 × 0.84／8 × six point six three × 2) = 1.34kgf / mm
3276.8/4599.936 = 0.712358 preload 0.65
when fixed, the compression is 2mm
tension spring
the K value of tension spring is the same as that of pressure spring
initial tension of tension spring: the initial tension is equal to the force required to properly pull apart the close springs and coils, and the initial tension occurs after the springs are rolled and formed. In the proction of tension spring, e to the different steel wire material, wire diameter, spring index, static electricity, grease, heat treatment, electroplating and so on, the initial tension of each tension spring is uneven. Therefore, when installing the tension spring of various specifications, it should be pre pulled until the distance between the parallel coils is slightly separated. The force required is called the initial tension. Initial tension = P - (k) × F1) = maximum load - (spring constant) × Tensile length) torsion spring
spring constant: expressed as K, when the spring is twisted, every 1 increase in the value of ° Load of torsion angle (kgf / mm). Formula of spring constant (unit: kgf / mm): k = (E) × d4)／1167 × Dm × p × N × R)
e = steel molus of wire: piano wire e = 21000, stainless steel wire e = 19400, phosphor bronze wire e = 11200, brass wire e = 11200 d = wire diameter do = od = outer diameter Di = id = inner diameter DM = MD = pitch diameter do DN = total number of turns r = arm of force under load p = 3.1416.
in the case of high school, f = KX, f refers to the elasticity, K refers to the stiffness coefficient, X refers to the shape variable, that is, the length change compared with the original length
in the case of middle school, the tension of the spring is calculated by balance
The spring force F = - KX, where k is the coefficient of elasticity and X is the deformation variable
after an object is deformed by an external force, if the external force is removed, the object can return to its original shape, which is called "elastic force". Its direction is opposite to that of the external force that deforms the object. Because there are many kinds of deformations of objects, the elastic force proced also has various forms
for example, when a heavy object is placed on a plastic plate, the bent plastic will return to its original state and proce upward elastic force, which is its supporting force to the heavy object. When an object is hung on a spring, the object elongates the spring. The elongated spring needs to return to its original state and proce upward elastic force, which is its pulling force on the object
extended data:
in the online elastic stage, the generalized Hooke's law holds, that is, stress σ 1< σ p σ P is the limit of proportion. It is not necessarily true within the scope of elasticity, σ p< σ 1< σ e σ E is the elastic limit), although in the elastic range, the generalized Hooke's law does not hold
According to Hooke's law of elasticity, when a spring is deformed, the elastic force F of the spring is directly proportional to the elongation (or compression) x of the spring, that is, f = k · X. K is the elastic coefficient of a material, which is only determined by the properties of the material and has nothing to do with other factors. A negative sign indicates that the force proced by a spring is opposite to its direction of extension (or compression) The elastic body satisfying Hooke's law is an important physical theoretical model, which is a linear simplification of the complex nonlinear constitutive relation in the real world, and the practice has proved that it is effective to a certain extent. However, there are also a large number of examples that do not satisfy Hooke's law in reality The significance of Hooke's law is not only that it describes the relationship between the deformation of elastic body and the force, but also that it creates an important research method: to simplify the complex nonlinear phenomena in the real world linearly, which is very common in theoretical physicsFn ∕ S=E· Δ l ∕ l
Where FN is the internal force, s is the area of FN, L. It's the original length of the elastomer, Δ L is the elongation after loading, and the proportional coefficient e is called the elastic molus, also known as young's molus ε=Δ l∕lis a pure number, so the elastic molus and stress are the same σ= FN / s has the same unit, and the elastic molus is the physical quantity describing the material itself. From the above formula, it can be seen that the elastic molus is larger when the stress is large and the strain is small; On the contrary, the elastic molus is smaller
the elastic molus reflects the resistance of materials to tensile or compressive deformation. For a certain material, the elastic molus of tensile and compressive amount is different, but the difference between them is not much, so they can be considered to be the same
· initial tension = P - (k) × F1) = maximum load - (spring constant) × Tensile length (mm)
Introction: Nowadays, with the development of the times, spring has generally appeared in our daily life, different springs have different functions, don't underestimate its small size, its role can be said to be weightless. In China, springs have been used since the early 1960s. This small series will take you to understand the stretch spring next
Application of tension spring:
another name of tension spring is spiral tension spring. Because of their wide range of action, they can be used in many occasions, such as research and development, experiment and maintenance, etc. Despite its small size, tension spring occupies a very important position in the global market. It is widely used in computer, electronics, automobile, medicine, railway, wind power, aerospace, engineering machinery and many other fields
characteristics of extension spring:
when the spring is under the action of external force, it will proce great elasticity to make it deform, so the working principle of extension spring is opposite to that of compression spring. When the compression spring is pressed tightly, it will play a reverse role, while the extension spring will play a reverse role only when it is extended or pulled apart. When the ends of the extension spring are pulled apart, the spring pulls them together. It's like a compression spring. The extension spring also absorbs and stores energy, but unlike the compression spring, because the spring under the action of external force will proce relatively large elasticity and deformation, so the extension spring is widely used as an elastic element in the aircraft
the calculation method of tension spring:
the calculation formula of tension spring is the same as that of pressure spring, the spring constant is expressed by K, the steel molus of wire is expressed by G, the wire diameter is D, the inner diameter is ID, and the effective number of turns is NC,
the formula is as follows: k = (g) × ID)/(8 × DM × NC)
the initial tension of the pull-up spring is equal to the force required to pull apart the tightly coupled springs, and the initial tension occurs after the spring is formed. In the proction of tension spring, because of the different steel wire material, wire diameter and static electricity, the initial tension of each tension spring will be unbalanced. Therefore, when installing the tension spring, we should first pull it between the parallel coils, and then separate some distance. We call it the initial tension
The formula is initial tension = P ×( k × F1) = maximum load ×( Constant of spring × Stretch length)
OK, the above is the stretch spring introced to you by this editor. Do you have a deeper understanding of it after reading it? Although it's small, it can't do without it in some occasions, so we can see how important it is
2. General force calculation formula:
P = P & # 39* F + P 0 (P, P & # 39; Stiffness, P0 initial tension)
P & # 39= GD ^ 4 / 8 / D ^ 3 / N (g material elastic molus, D material diameter, D spring pitch diameter, n effective turns)
G = 78500 (carbon steel wire), g = 71600 (stainless steel wire), g = 81000 (piano steel wire)
unit of force: n, unit of dimension: mm
3, Fatigue strength checking calculation is needed.
please refer to gbt1239.6-1992 or gbt23935-2009 for details
Calculation method:
spring constant: expressed by K, when the spring is stretched, the load (kgf / mm)
spring constant formula (unit: kgf / mm): k = (g * D4) / (8 * DM3 * NC)
G: rigid molus of wire rod; d: Wire diameter; DM: pitch diameter = outer diameter - wire diameter; NC: effective turns = total turns - 2
initial tension of tension spring: the initial tension is equal to the force required to pull apart the springs close to each other, and the initial tension occurs after the spring is rolled and formed. In the proction of tension spring, e to the different steel wire material, wire diameter, spring index, static electricity, grease, heat treatment, electroplating and so on, the initial tension of each tension spring is uneven
therefore, when installing the tension springs of various specifications, it is necessary to pre pull them until the distance between the parallel rings is slightly separated. At this point, the required force becomes the initial tension
initial tension = P-K x L = maximum load - spring constant x tensile length
extended data:
characteristics of tension spring:
many different terminal devices or "hooks" are used to ensure the tension source of tension spring. The working principle of tension spring is opposite to that of compression spring. The compression spring reverses when it is compressed, while the extension spring reverses when it is extended or pulled apart. When both ends of the extension spring are pulled apart, the spring tries to pull them back together. Like compression springs, extension springs also absorb and store energy
But unlike compression springs, most extension springs are usually under a certain degree of tension, even without any load. This initial tension determines the tightness of the tension spring coil without any loadelastic limit refers to the ability of metal material to resist the external force of a certain limit when the external force is removed
if the tensile force continues to increase, the object will proce plastic deformation until fracture (take the round bar tensile sample for example, with the increase of tensile force, the round bar sample will proce elastic deformation; When the tensile force exceeds the elastic limit, the round bar begins to yield; The tensile force continues to increase until the tensile limit, and the round bar breaks