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It all started in 1945, when my father, Knud Hagens,
an engineer, decided to open his own bicycle repair shop. This included a
mechanical workshop in a basement, in the back room of which he would
manufacture springs of thin wire.
Many initiatives have taken place since then, and
today we manufacture our springs in environmentally desirable plants in Brovst
and Støvring. Our deliveries from Støvring include, among other things, very
small and powerful springs for industry in both domestic and foreign markets –
including the extension springs mentioned in this booklet.
The management is located in Støvring. Directors and
managers of this company are now second-generation, with a professional board
and a staff of 100 skilled employees, many of whom have several years of
experience within this trade.
Our modern production facilities and services,
ensuring flexibility and high quality in our spring design,
mean that we are certain to meet your requirements.
Best regards
Peter Hagens
Materials
In order to meet the requirements of our customers, we
stock materials of various dimensions and qualities. All our suppliers are
reputable, supplying materials made of only the very best rolled wire. Thus we
ensure uniform production and a high-quality end-product.
We are pleased to supply material specifications
together with the springs, to the extent that this is required.
Wire is produced
according to established standards. This applies to the alloys used, the
ultimate strengths and the wire diameter, as well as to the production limits
of the springs.
Our products conform mainly to DIN standards,
including the EN and ISO standards.
Spring wire has to be very elastic when in use. Because
the limit of elasticity is very high, the limit of deformation becomes as high
as possible. When the limit of elasticity is exceeded, however – which is
necessary during the manufacturing process of springs – the deformability of
spring wire also has to remain sufficiently high.
Most springs are made of spring wire, which is carbon
steel, holding a C-content of
0.5-1.2%, varying according to strength. By means of a special hardening
process called patenting, followed by drawing, ultimate strengths of approximately
3,000n/mm2 are
obtainable.
The most commonly used patented spring wire is graded
according to strength, measured in accordance with DIN 17223-1:
DIN 17223-1, D and C Highest
ultimate loads Used for all
kinds of especially high-stressed springs.
DIN 17223-1, B Medium
ultimate loads Mainly used for compression springs, torsion springs,
special springs, i.a.
DIN 17223-1, A Lowest
ultimate loads Used for
extension springs, the low strength and high deformability being an advantage
to the working-out of the loop. Furthermore, it is used for spring rings, wire
forms and other kinds of wire shapes.
Additionally,
we have oil-hardened wire (DIN 17223-2), which is characterised by high
ductility and extremely good deformability, and special
Many springs are made of
stainless materials (DIN 17224). Springs with stainless qualities, like 18/8,
in accordance with Werkstoff No. 1.4310, or, alternatively, Werkstoff No.
1.4401, are the most common. If saline-resistant or non-magnetic springs are
required, however, we use hard-drawn bronze wire, holding approximately 7% Sn.
Moreover, beryllium copper
wire, requested specially by the electrical and electronic industries, ought to
be mentioned. Because of its characteristics, this material will do justice to
itself in these areas.
Springs are also made of brass, copper, aluminium,
German silver, and other materials.
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In the cross-section of a compression spring the dispersion of the
shear stresses is irregular. The stresses of the inside of the coils are higher
than the stresses of the outside of the coils.
The correction factor k, used when checking the load, takes this into
account.
The correction factor k is dependent on the diameter index D/d, and
appears in the diagram below:
Compression springs are manufactured with different types of ends. The
following drawings show these:
XXX XXX XXX
A: Ends not closed, and unground
B: Ends closed and unground
C: Ends closed and ground
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The following diagram shows a compression spring with ends closed and
ground.
Compression springs are manufactured with ends either closed or not
closed, and with ends either ground or unground. Usually, springs with a wire
diameter less than 1.0 mm are manufactured with ends unground. This is also the
case where compression springs are manufactured with large spring indexes.
HH, 26.03.2002