Muelles Crom. Spring manufacturers leaders in design, quality and service since 1953

SPRING DESIGN

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

muellescromingenieria-02



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.

Muelles Crom

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