TPT May 2010

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40 M ay 2010 ›
Technology Update
DALIAN Field Company is an ERW pipe
mill manufacturer that prides itself on
developing quick-change technology. The
company has many approved patents in this
area such as cage forming for square pipe
forming machines, which operate without
changing rollers when changing product
size. The cage forming square and round
pipe forming machine is the first machine
to combine cage and directly square and
rectangular forming together, less roller
quantities, shorter changeover time and a
higher degree of automation.
Along with the further development of
pipe mill technology, Dalian Field said it
has conducted a number of studies on
simplifying the operation of a pipe mill.
‘Digital – no load – setting – adjustment’
(DNSA) technology was brought in
following the research. Firstly, all setting
points are displayed in a numerical way, as
numeralisation is the foundation of DNSA
technology and leads to many important
improvements.
For example, it is used when
building a mathematic model to program
the adjustment of the mill. Even an
inexperienced worker can adjust the mill
to high precision and produce qualified
pipes with little or no waste after reading
the manual or 10 minutes simple training.
The mill with DNSA technology not only
has less waste, a shorter time to make
adjustments and low dependence on
operator’s experience, but also has a
trouble-free operation. From a practical
point of view, the mill has good tolerance
with the raw material and strip joint quality,
because the rollers are in pinpoint control.
A normal pipe mill is also able to produce
qualified products, but often depends on
the operator’s experience. The adjustment
is done wth the eye of an experienced
worker. They cannot ensure each roller is
in exactly the correct position. They can
only adjust the mill to produce qualified
pipes.
For the DNSA pipe mill, every roller is
in the correct position, so the mill’s working
condition is stable, and the mill has a
strong ability to resist outside interference.
For the normal pipe mill, every roller may
not be in the correct position and the
adjuster does not know which roller is
in the wrong position and how much the
offset is. They can only can adjust rollers
by observing the actual running strip.
Sometimes correct rolls are adjusted and
wrong rolls are not adjusted, then all the
rollers are adjusted on an offset position. It
also can produce qualified pipes, just like
the mathematical law – double negatives
makes a positive. The problem is that the
mill working condition is not stable even
in a critical condition. Every tiny change
of the mill may break the balance. That is
why some adjusters can spend longer than
needed making constant changes to the
mill. The busier the adjuster, the lower the
product quality and quantity and the lower
the profit.
In the pipe industry the adjustment
time for producing the end products is
important to the end user. Some pipe
mill manufacturers may fail to notice this,
when they are focusing on the methods of
changing rolls. The adjustment problems
are exposed, after the changeover period is
shortened and the workload is reduced by
the improvement of mill construction. These
problems can be classified as adjustment
duration, adjustment workload, rawmaterials
and power consumption. Those who have
the experience of producing ERW pipes
know how important an adjuster is. Also, to
train a qualified pipe mill adjuster can take
a very long time.
Since high quality, speed mills are
popular in the market, the company said the
ERW pipe mill with DNSA technology could
become important for future ERW pipe mills
due to its efficient performance.
Dalian Field – China
Fax: +86 41183 192716
Email:
Website:
New trends for ERW pipe mills
The Dalian Field ERW pipe mill