SPRING DESIGN
Basic and elementary in the calculation and design of springs.
BASIC PRINCIPLES
There are three basic principles in spring design
- The heavier the wire, the stronger the spring
- The smaller the coil, the stronger the spring
- The more active coils, the less load you will have to apply in order to get it to move a certain distance.
ENGINEERING DEPARTMENT
& PROCESS OF MUELLES CROM
Compression Spring Software V3000 Copyright 2.013
Muelles CROM Design engineering + Compression Spring Software V15.64 #0410
Compression spring No.: 2098-4x32x120
Application : Hans ecker Maschinenelemente, Hanser Verlag
EN 10270-1 SH spring steel wire pat.drawn
Manufacturing : cold-coiled
Spring ends : lined-up and ground
Stress : static
Surface : drawn
Manufacturing compensation : no comment
adm.deviation De,Di,Dm : to DIN 2095 Quality Class 2
adm.deviation L0 : to DIN 2095 Quality Class 2
adm.deviation F1, F2 : to DIN 2095 Quality Class 2
adm.deviation e1, e2 : to DIN 2095 Quality Class 2
adm.deviation d : to DIN 2076 C
modulus of elasticity | E | N/mm² |
206000
|
shear modulus | G | N/mm² |
82000
|
density | rho | kg/dm^3 |
7.85
|
tensile strength | Rm | N/mm² |
1788
|
adm.shear stress | tauz | N/mm² |
1001
|
operating temperature | theta | °C |
20
|
shear-modulus at working temperat. | G 20 | N/mm² |
82000
|
MAIN DIMENSIONS
wire diameter | d | mm |
4 +/- 0.025
|
inside diameter | Di | mm |
28
|
mean coil diameter | Dm | mm |
32
|
outside diameter | De | mm |
36 ± 0.5
|
nos of coils | n(if) |
8.5
|
|
inactive end coils lower side |
1
|
||
inactive end coils upper side |
1
|
||
Total number of coils | nt |
10.5
|
SPRING LENGTHS
free length | L0 | mm |
120 ± 2.29
|
spring length at load F1 | L1 | mm |
120
|
spring length at load F2 | L2 | mm |
48.93
|
usable spring length | Ln | mm |
48.93
|
Solid length of spring | Lc | mm |
42.26 -0.262
|
SPRING LOAD
spring load at L1 | F1 | N |
0 ± 21.6
|
spring load at L2 | F2 | N |
669.5 ± 31.6
|
spring load at Ln | Fn | N |
669.6
|
spring load at Lc | Fc th | N |
732.4
|
SPRING TRAVELS
stroke | sh | mm |
71.07
|
spring travel | s1 | mm |
0.00
|
spring travel | s2 | mm |
71.07
|
usable spring travel | sn | mm |
71.07
|
spring travel to Lc | sc | mm |
77.74
|
Excursion until Buckling | sk | mm |
27.14
|
TENSIONS
shear stress at F1 | tau 1 | N/mm² |
0
|
shear stress at F2 | tau 2 | N/mm² |
852
|
shear stress at Fn | tau n | N/mm² |
853
|
shear stress at Fc th. | tau c | N/mm² |
932
|
stress coefficient | k |
1.172
|
|
corrected shear stress at F1 | tau k1 | N/mm² |
0
|
corrected shear stress at F2 | tau k2 | N/mm² |
999
|
adm. shear stress | tau z | N/mm² |
1001
|
Bearing Application Coefficient | nue |
1
|
|
Deviation of Surface Line | e1 | mm |
6
|
Deviation of Parallelism | e2 | mm |
1.08
|
spring rate | R | N/mm |
9.421
|
natural frequency | fe | 1/s |
167.2
|
Increase in Coil Diameter at Lc | deltaDe | mm |
0.436
|
Minimum clearance of active coils | Sa | mm |
6.66
|
Actual clearance of active coils | sc-s2 | mm |
6.67
|
coiling ratio | w |
8
|
|
Gradient ratio | tan alfa |
0.13
|
|
Gradient | m | mm |
13.65
|
Gradient ratio | Dm/m |
2.34
|
|
Lean grade | lambda |
3.75
|
|
spring energy between s1 and s2 | W12 | Nmm |
23792
|
weight of the spring | m | g |
104.1
|
wire length | L | mm |
1056
|
pressure | R/D | N/mm² |
0.294
|
Max.diameter of bedding mandrel | Ddmax | mm |
27.48
|
Minimum diameter of bore | Dhmin | mm |
36.96
|
REMARKS, WARNINGS AND ERROR MESSAGES
Warning: bending ! |
bending of the spring before extension 2 is reached. (see bending diagram) |
the bending security will be improved by better bedding, larger coil diameter Dm, smaller spring lemgth L0 |
Warning: setting þ2/þz=0.85) |
tension tau2 is more than 70% of tau perm, after a time the spring forces will be reduced. |
increase wire diameter, use material of higher strength. |
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Author: Muelles Crom
MUELLES CROM was founded in 1953 in Granollers. We currently have production facilities in Granollers and Les Franqueses del Vallès.