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1)
Overview
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Space can be efficiently
used and the initial length of the spring
can be effectively used.
Extension spring is commonly used like compression
spring and has various hook shape
according to the application. |
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2)
Application |
Components for automobile,
electrical, electronic, stationery, toy, industry,
and information-
communication |
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3)
Shape |
It has hooks at the both
ends. |
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4)
Manufacturing
capability |
We manufacture extension
springs with a diameter of Ø 0.2mm to Ø
6mm. |
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5)
Others |
Plating, coloring, power
coating etc available |
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6)
Symbols used
for extension spring design |
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Item |
Symbol |
Item |
Symbol |
shear modulus
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G
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mounting length
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I |
wire diameter
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d |
initial load
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Po |
outside diameter
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Do |
initial stress
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mean coil diameter
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Dm |
Load
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P |
inside diameter
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Di
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spring constant
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K |
total number of coils
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Nt
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index ratio
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C |
number of active coils
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Ne |
stress correction coefficient
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k' |
free length
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L |
shear stress
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tensile strength
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a) Spring constant : K = G * d
³ / 8 * Ne * Dm ³
b) Initial load : Po = π * d ³ *
/
8 * Dm (Refer to the graph below for .)
c) Load : P = K * (L - l) + Po
d) Stress correction coefficient : k' = {(4
* C-1) - (4 *C-4)}+(0.615/C)
e)
= k' * 8 * Dm * P/ π * d ³
f) Stress ratio = /
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