Page 558 - MiSUMi FA Mechanical Components Economy Series

Economy Series
Technical Calculations Springs [Technical Calculation] Spring Excerpted from GB/T 23935-2009

1 Parameter Names and Codes of Springs K in the formula is the Stress Correction factor(Wahl factor), and the value of K is calculated according to Formula (7):
Coil Springs Parameter Name Table 1 Unit Under static load, the value of K can generally be taken as 1. When the spring stress is high, the value of K is also considered.
4C─1 0.615
This standard uses the terms and symbols specifi ed in GB/T 1805-2001 and Table 1.
EEEEEEEEEEEEEEEEEEEEE(7)
K=
+
C
4C─4
Code
3.1.5 Spring Wire Diameter:
π[τ]
π[τ]
P.545 Wire Diameter d mm d ≥ 8KDF or d ≥ 8KCF EEEEEEEEEEEEEEEEE (8)
mm
Spring I.D.
D 1
[τ] in the formula is the Allowable Torsional Stress determined according to the above design conditions.
Spring O.D.
mm
3.1.6 Spring Mean Diameter:
Tension Springs Spring Mean Diameter D Coils D=Cd EEEEEEEEEEEEEEEEEEEEEEEEE(9)
D 2
mm
3.1.7 Eff ective Number of Coils of Spring:
Total Number of Coils
Gd 4
Number of Supporting Coils n1 Coils n= 8D 3 F f EEEEEEEEEEEEEEEEEEEEEEE(10)
nz
P.555 Eff ective Number of Coils n Coils 3.2. Natural Vibration Frequency
Posts For Tension Springs Free Height (Free Length) H0 mm For the cylindrical helical coil springs with fi xed ends and one end periodically reciprocating within the
working stroke range, its natural vibration frequency is calculated according to Formula (12):
mm
Solid Height
3.56d
G
H b
nD 2 EEEEEEEEEEEEEEEEEEEEE(12)
fe=
ρ
t
mm
P.561 Pitch F 1,2,...n ―― 3.3 Spring Characteristics and Defl ection
Load
N
3.3.1 Spring Characteristics
Torsion Springs/ Disc Springs Material Shear Modulus τ1,2,...n MPa b) When it is necessary to ensure the height under the load, the defl ection
K
Stress Correction factor(Wahl factor)
a) When it is necessary to ensure the load at the specifi ed height, the
defl ection of the spring shall be between 20% and 80% of the defl ection
G
under the test load, i.e. 0.2 fs ≤ f1, 2, ...n ≤ 0.8 fs .
Torsional Stress
MPa
test load, i.e. 0.2 fs ≤ f1, 2, ...n ≤ 0.8 fs , but the load under the maximum
P.564 Allowable Torsional Stress [τ] MPa of the spring shall be between 20% and 80% of the defl ection under the
defl ection should be no greater than the test load.
Initial Tension F 0 N c) When it is necessary to ensure the stiff ness, the defl ection of the spring
Shock Absorbers 2 Principle of Allowable Stress Selection shall be between 30% and 70% of the defl ection under the test load, i.e.
f1 and f2 meet the conditions of 0.3 fs ≤ f1, 2 ≤ 0.7 fs . The spring stiff ness
a) For springs under static load, in addition to considering strength
is calculated according to Formula (13):
conditions, if there are requirements for stress relaxation, the
allowable stress shall be appropriately reduced.
=
─
f 2 f 1 H1 ─ H2
P.567 b) For springs under dynamic load, in addition to the number of cycles, F' = F2 ─ F1 F2 ─ F1 EEEEEEEEEEEEEEEEEEE (13)
the stress (change) amplitude should also be considered, which 3.3.2 Spring End Structure Type
11 is calculated according to the cycle characteristic formula (1), and See Table 2 for the spring end structure type.
checked in Figure 2. When the cycle characteristic value is large, Shape Code Sketch Table 2 End Structure Type
Springs / Shock Absorbers  min  F min or σmin  T min  П min EEEEEEE(1) YI Both end coils tightened
that is, the stress (change) amplitude is small, the allowable stress
is taken as the large value; and when the cycle characteristic value
is small, that is, the stress (change) amplitude is large, the allowable
stress is taken as the small value.
and grinding
n Z ≥ 2
max
σmax
F max
П max
T max
c) For springs in important applications, where damage has a
signifi cant impact on the entire machinery, and springs operating Both end coils tightened
at higher or lower temperatures, the allowable stress should be Cold Coil Compression Spring YII but not grinding
reduced appropriately. n Z ≥ 2
d) The fatigue strength or fatigue life of the spring can be improved by
eff ective shot peening treatment.
e) For the coil springs, the fatigue life can be increased by eff ective Both end coils not
strong pressure treatment, which has obvious eff ect on improving YIII tightened
the performance of the spring. n Z < 2
f) There are many factors aff ecting the fatigue strength of springs
under dynamic load, which are diffi cult to estimate accurately. For
springs for important purposes, test verifi cation should be carried out Both end coils tightened
after the design is completed. RYI and grinding
n Z ≥ 1.5
3 Design Calculation of Cylindrical Helical Coil Springs
3.1 Basic Calculation Formula
3.1.1 Spring Load: Both end coils tightened
Gd 4
F= f EEEEEEEEEEEEEEEEEEEEEE(2) RYII but not grinding
8D 3 n n Z ≥ 1.5
See Appendix A for the material shear modulus G in the formula.
3.1.2 Spring Defl ection: Hot Coil Compression Spring
8D 3 nF
f = EEEEEEEEEEEEEEEEEEEEEE(3) Both end coils fl attened,
Gd 4 RYIII tightened and grinding
3.1.3 Spring Stiff ness: n Z ≥ 1.5
F Gd 4
F' = f = 8D 3 n EEEEEEEEEEEEEEEEEEEE (4)
3.1.4 Spring Tangential Stress: Both end coils fl attened,
8DF RYIV tightened but not
τ =K πd 3 EEEEEEEEEEEEEEEEEEEEE (5) grinding
or n Z ≥ 1.5
Gdf
555 τ =K πD 2 n EEEEEEEEEEEEEEEEEEEEEE (6)