How to calculate the shrinkage force

1. At present, there is no generally accepted calculation formula for welding shrinkage stress. Therefore, there is no applicable calculation method of shrinkage stress
the reasons are as follows: 1. There are many welding methods and kinds of heat sources, so the stress can not be unified; 2. The physical properties of welding base metal and welding material are inconsistent; 3. Human factors cannot be ruled out
therefore, I think the research on accurate calculation of welding is still in the development stage, waiting for people with lofty ideals to develop it.

2.

Finally, the task of exerting force is to apply the whole body force to the javelin in the shortest time through the throwing arm and hand action on the basis of the stable support of both feet, so as to achieve a greater release speed. Therefore, whether the javelin can complete the displacement from the position at the end of run-up to the release point in the shortest time under a certain working distance, It depends on the strength of the muscles

According to the principle of momentum: ft = m (v. -) 5) = m △ V

in the above formula: v. V is the speed at the end of the run-up, f is the force exerted by the throwing arm on the javelin, and T-F is the action time

Compared with javelin,

△ V is the speed change of javelin, and for human body, it is the speed of completing throwing action. When the range of motion is fixed, that is, t is relatively fixed, f is proportional to △ v. Therefore, muscle contraction is the key factor to determine the degree of action

It can also be seen from the formula that when f is fixed, t is proportional to △ V, but the increase of t can only be obtained by depending on the extension of working distance, not by artificial subjective extension. On the contrary, people should try their best to shorten the action time subjectively in order to obtain good throwing effect. On this point, we can draw the following conclusion: assuming that the speed of the gun before the final force is V, The release speed is v., Since the motion in the process of gun throwing can be approximately regarded as uniform acceleration motion, it is concluded that:

ft = MV

s = 12at2

V = at

when the working distance s is fixed, shortening the action time t will have a positive effect on the increase of the force F of the human body on the gun. Similarly, when the force is fixed, the increase of the working distance s will also help to improve the force F. Therefore, improving the contractility of the related active muscles and their cooperative muscles is concive to improving the Javelin Athletes' movement speed

3. The maximum compression force is greater than 1400N. The specific amount depends on the diameter and stroke. It is expected to be about 1500N
Longxiang gas spring

4.

The calculation formula of shrinkage is (before-after) / before * 100%. Shrinkage percentage

The shrinkage s is expressed by the following formula: S = {(D-M) / D} × 100% (1)

in which: s-shrinkage; D - die size; M-Size of plastic part

the following is the shrinkage of plastic, unit (%)

PP (1.0-2.5)

PMMA(0.1-0.4)

PC(0.5-0.7)

PA6(0.5-1.5)

PA6-GF(0.4-0.6)

PA66(0.8-1.5)

PA66-GF(0.5)

PS(0.4-0.7)

ABS(0.4-0.9)

ABS-GF(0.1-0.2)

POM(2-2.5)

PBT(1.5-2.0)

PET(2-2.5)

the above is the shrinkage ratio of commonly used plastics, which has a range. If the manufacturer doesn't specify it, take the middle value

extended data:

1. The effect of mold structure on shrinkage of plastic procts

(1) the shrinkage decreases with the increase of gate size

(2) the shrinkage in the direction of vertical gate decreased, while that in the direction of parallel gate increased

(3) the shrinkage far away from the gate was smaller than that near the gate

(4) the shrinkage of the plastic part with mold restriction is small, and that of the plastic part without mold restriction is large

(1) the shrinkage of crystalline plastics is higher than that of amorphous plastics

(2) the plastic with good fluidity has low molding shrinkage

(3) when the filler was added into the plastic, the shrinkage rate decreased significantly

(4) different batches of the same plastic, molding shrinkage is not the same

(1) the shrinkage of thick wall plastic parts is higher than that of thin wall plastic parts (but the shrinkage of most plastic parts with 1 mm thin wall is higher than that of 2 mm thin wall parts, which is e to the increased resistance of melt in the mold cavity)

(2) the shrinkage of plastic parts with inserts is smaller than that without inserts

(3) the shrinkage of plastic parts with complex shape is smaller than that with simple shape

(4) the shrinkage of plastic parts in the height direction is generally smaller than that in the horizontal direction

(5) the shrinkage of slender plastic parts in the length direction is small

(6) the shrinkage rate of the dimension in the length direction is smaller than that in the thickness direction

(7) the shrinkage rate of the inner hole was higher than that of the outer hole

source of reference: network shrinkage of plastics

source of reference: network shrinkage

5. It's so simple. First of all, for the cylinder you selected, he will definitely provide the parameters of pushing and pulling force under how much pressure. If you can't calculate, I will give you a formula, f = PS = P * (PI) * r * r, the area of cylinder diameter for pushing out, the area of cylinder diameter for retracting minus the area of push rod. You can calculate the pushing and pulling force. As for pushing each other, I don't care if you don't interact with each other, you are just like a wall, and the forces on both sides are the same, How much on one side is how much on the other side. If one side is big and the other side is small, one side will definitely run. It's not whether it's one or not. It's interaction

6. The film is flat and the glass is banded. If you do not use a high-temperature baking gun to shrink the film before applying the film, you can not attach it to the glass smoothly. Moreover, after the high temperature test of the film, in the future under the high temperature of the sun, it will no longer be hot expansion and cold contraction to damage the glass.

7.

Calculation 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

{rrrrrrr}

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 spring

8. Besides the spring size, the design data of pressure spring need to calculate the 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 = 3500d = wire diameter do = od = outer diameter Di = id = inner diameter DM = MD = middle diameter do DN = total number of turns NC = effective number of turns = n-2 spring constant calculation example: wire diameter = 2.0mm, outer diameter = 22mm, total number of turns = 5.5 turns, steel wire material = piano wire k = (G × ｄ４)／８ × Ｄｍ３ × Ｎｃ＝８０００ × ２４／８ × ２０３ × 5) = 0.571kgf/mm, the K value of tension spring is the same as that of pressure spring. The initial tension of tension spring: the initial tension is equal to the force required to pull apart the close springs and coils. 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 constant: expressed in K, when the spring is twisted, every increase of 1 ° 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 = 11200d = 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

9. If the result is positive, it means that it is tensile force; if it is negative, it means that it is compressive force