How to calculate the spring preload state force
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 retainedCalculation of spring weight (kg):
wire diameter × Wire diameter × Total number of spring turns × Pitch diameter of spring × one point nine three seven ÷ 100000
elastic formula
F = KX, f is elastic force, K is stiffness coefficient (or obstinacy coefficient), and X is the length of spring lengthening (or shortening). Example 1: when a spring with a stiffness coefficient of 100N / M is pulled by 5N force, the spring will be lengthened by 5cm. Example 2: when a spring is pulled by 10N force, the total length is 7cm, and when it is pulled by 20n force, the total length is 9cm
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extended data:
structure classification
< P > according to the mechanical properties, springs can be divided into tension spring, compression spring, torsion spring and bending spring, according to the shape, they can be divided into disc spring, ring spring, plate spring, spiral spring, truncated cone scroll spring and torsion bar spring, According to the manufacturing process can be divided into cold coil spring and hot coil spring. Ordinary cylindrical spring is widely used because of its simple manufacture, various types and simple structure Generally speaking, the manufacturing materials of spring should have high elastic limit, fatigue limit, impact toughness and good heat treatment performance, and the commonly used ones are carbon spring steel, alloy spring steel, stainless spring steel, copper alloy, nickel alloy and rubber. The manufacturing methods of spring include cold rolling and hot rolling. The diameter of spring wire less than 8 mm is generally cold rolled, and the diameter greater than 8 mm is hot rolled. Some springs need to be pressed or shot peened after being made, which can improve the bearing capacity of the springbesides 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.
· spring constant: expressed by K, when the spring is compressed, the load (kgf / mm) increases by 1 mm
· spring constant formula (unit: kgf / mm):
G = steel molus of wire rod: piano wire g = 8000; Stainless steel wire g = 7300, phosphor bronze wire 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 = 2.0mm, outer diameter = 22mm, total number of turns = 5.5, Steel wire material = piano steel wire
tension spring
the K value of tension spring is the same as the calculation formula of pressure spring
· initial tension of tension spring: the initial tension is equal to the force required to pull apart the close springs and coils, 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 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).
· spring constant formula (unit: kgf / mm):
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 = od
Di = id = ID
DM = MD = pitch diameter = do-d
n = total number of turns
R = arm of force acting on load
P = 3.1416
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