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Technical data - Extension springs - Range A & B

Material

Music wire:
DIN 17223 C-WIRE WERKSTOFF NO. 1.1200
Working temperature between -30 ºC and +120 ºC

Stainless steel:
DIN 17224 AISI 302 WERKSTOFF NO. 1.4310
Working temperature between -200 ºC and +250 ºC

 

Range A: The A Range consists of springs with 5 digits, ie: 31200
All dimensions and forces in accordance with DIN 2097 (Grade 2). DIN 2097 defines the force as the determining parameter. The number of coils may therefore vary and is consequently not stated for these ranges.

The tolerance of the diameter and length is defined based on the tables below:

Dm Tolerance in mm
Dm Gütegrad 2  
Coil ratio 
W
From To 4  -  8
+ / -
8  -  14
+ / -
14  -  20
+ / -
0,63
1,00
1,60
1,00
1,60
2,50
0,07
0,08
0,10
0,10
0,10
0,15
0,15
0,15
0,20
2,50
4,00
6,30
4,00
6,30
10,00
0,15
0,20
0,25
0,20
0,25
0,30
0,25
0,30
0,35
10,00
16,00
25,00
16,00
25,00
31,50
0,30
0,35
0,40
0,35
0,45
0,50
0,40
0,50
0,60
31,50
40,00
50,00
40,00
50,00
63,00
0,50
0,60
0,80
0,60
0,80
1,00
0,70
0,90
1,10
63,00
80,00
100,00
80,00
100,00
125,00
1,00
1,20
1,40
1,20
1,50
1,90
1,40
1,70
2,20
125,00 160,00 1,80 2,30 2,70
 
L0 Tolerance in mm
L0 Gütegrad 2  
Coil ratio 
W
From To 4  -  8
+ / -
8  -  20
+ / -
0,00
10,00
16,00
10,00
16,00
25,00
0,40
0,50
0,60
0,50
0,60
0,70
25,00
40,00
63,00
40,00
63,00
100,00
0,80
1,10
1,50
0,90
1,30
1,80
100,00
160,00
250,00
160,00
250,00
400,00
2,00
2,50
3,00
2,40
3,00
4,00
400,00 8 1,5% of L0 1,5% of L0



Range B: The B Range consists of springs with 11 digits, ie: E03600552000M
The tolerance of the external diameter and length is defined based on the tables below:

Range B  External diameter - tolerance in mm
1,45mm - 3,02mm +/- 0,08mm   31,14mm - 37,08mm +/- 0,76mm
3,05mm - 6,10mm +/- 0,13mm   37,11mm - 50,08mm +/- 1,02mm
6,12mm - 12,70mm +/- 0,20mm   Force Tolerance
12,73mm - 25,40mm +/- 0,38mm   Fn max load +/- 10%
25,43mm - 31,12mm +/- 0,51mm   Spring constant R  +/- 10% 
 
Range B Lo tolerance in mm
Length Tolerance
3,05 - 25,40mm +/- 0,79mm
25,41 - 38,10mm +/- 1,58mm
38,11 - 88,90mm +/-3,18mm
Fra 88,91mm +/-4,78mm




 
Terminology

d = Wire diameter in mm
De = External diameter in mm (D+d)
D = Mean diameter in mm (De minus d)
L0 = Unloaded length internal in loops
Lk = Unloaded length of spring body in mm
L1 = Loaded length internal in loops at F1
L2 = Loaded length internal in loops at F2
Ln = Loaded length (max.) internal in loops at Fn
. . F0 is for guidance only, as F0 can fluctuate greatly due to differing production processes.
F0 = Initial force (prestress) in N (Newtons) with unloaded spring
F1 = Partial load in N (Newtons) at L1
F2 = Additional load in N (Newtons) at L2
Fn = Maximum load in N (Newtons) at Ln (should not be used)
sn = Maximum travel (extension) in mm at Fn (should not be used)
R = Spring constant in N/mm
m = Opening (space) at loop in mm
X = Loop position
1 N = 0,10197 Kp
1 Kp = 9,80665 N

Traek fjeder
 
Calculation of spring force

Fn for stainless steel spring steel is approx. 0.88 x Fn for music wire.

 

Calculation of the initial force (F0):
The initial force F0 or the initial tension is for guidance only due to differing production processes.
F0 = Fn - (R * Sn).  A rule of thumb is however that F0 is 10-15% of Fn.

For example, for stock number 32600, Fn = 237 N, R = 2,67N/mm og Sn = 75,70mm.
F0 = 237N - (2,67N/mm * 75,70mm) = 237N - 202N = 35N 

 

The calculation of spring force for a given length:
Calculation of spring force at a given length is: F0 + (travel * R).
For example, for stock number 32600 where R = 2.67 N/mm, the desired travel is 55 mm and F0 is approx. 35 N. 
35N + (55mm * 2,67N/mm) = 35N + 147N = 182N 

 
Loops

A range:

Closed German loops in accordance with DIN 2097, random angle.

Tolerance at loop height (LH) is from 0.8 to 1.1 * Dm. The loop position (X) is variable and the loops can therefore be turned in relation to one another. The diameter of loops may well exceed the external diameter of the body. The tolerance for deviations is determined based on the definition below. Standard springs are produced based on Grade 2.

Coil ratio Gütegrad 1 Gütegrad 2 Gütegrad 3
<6 0,5 * d d 2 * d
6-12 0,75 * d 1,5 * d 3 * d
>12 By agreement or by choice of production

Example: Stock number 32600 has a wire thickness of 2.5 mm. The external diameter is 18 mm, which produces a mean diameter of 15.5 mm. From the table above, we can determine how wide the loop must be. First we must work out the coil ratio using the formula Dm/d. The loop width can then be determined using the table above.
Coil ratio: 15.5 mm/2.5 mm = 6.2 mm
Loop width: 18 mm + (1.5 * 2.5 mm) = 21.75 mm


Serie B:
Loops in this range are closed loops without a specific loop shape and with a random angle. Every effort is made to keep the same external diameter as the spring body. However, the external diameter of the loop may vary.

 
Winding direction

Normally right-handed.

Standard springs are not defined with a specific direction of wind. Depending on production, the springs may be produced either right or left wound. If you require a specific direction of wind a special spring must be produced. 


 

If an extension spring with an exact value for one of the following parameters is required, springs must be custom-made:

  • Loop type
  • Loop height (LH)
  • Loop position (X)
  • Loop width (if the spring is to be incorporated into a tube) 
  • Opening at loop (m)
  • Initial force (F0)


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