Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS FOR PRODUCING METAL TUBES, AND TRANSPORTATION RACK
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for producing metal
tubes, such as copper tubes, as well as to a transportation rack
for shipping the tubes wound in coils.
2. The Prior Art
Copper tubes are usually manufactured from billets in a hot
molding process via extruders or pilger rolls. The puddled
pressed tubes are subsequently processed further with pilger
rolls or by drawing. Further processing may take place by
individual or multiple drawing. Further transport to the next
processing stage is carried out with a basket transport system,
as a rule.
It has been known heretofore to manufacture copper tubes in
the production plant continuously in one line, starting with the
casting of the billets followed by the hot molding process, and
ending with the final drawing process. The costs for purchasing
the extrusion plants employed for the hot molding process are
very high, and such equipment has a high production capacity.
However, for the special production of copper tubes, the capacity
of an extrusion plant can only be partially utilized even by
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producers manufacturing copper tubing in large volumes. The
manufacture of other product lines on such equipment such as,
sections or bars, does lead to improved utilization of the
capacity of the extrusion plant. However, this also results in
considerable additional costs due to the required refitting work,
which have an adverse effect on the price of the semifinished
products. Furthermore, the plant is shut down for the refitting
work, which leads to further costs.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a
process for the production of metal tubes made of metal, in
particular copper tubes, that permits improved utilization of the
capacity of the production equipment, as well as economical
production, and by which finished tubes can be produced simply at
favorable costs.
It is another object of the invention to provide a suitable
transportation rack for shipping the tubing wound into large
coils.
The proposed discontinuous procedure for producing copper
tubes, at two locally separated production sites, first in the
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form of a preliminary product and at a later time as a finished
product, significantly lowers the overall manufacturing cost of
such tubes. In a first production plant, initial tubes that can
be wound into coils are first produced by extruding or hot
rolling, and drawing. The stages extruding and hot rolling, which
each are followed by drawing, are carried out via technology that
is generally known and commonly utilized in the field of
manufacture of copper tubing.
Following drawing of the tubes on a continuous drawing
machine into initial tubes with an outside diameter of from 35 to
80 mm and a wall thickness of from 1.5 to 4.0 mm, the initial
tubes are wound into large coils on a suitable winding machine.
The large coils are preferably wound layer on layer into so-
called "LWC~~-coils with a constant inside diameter of at least
800 mm, and a maximum outside diameter of up to 3500 mm. LWC-
tubes have been used heretofore only for near-end dimensions,
i.e, the wall thickness is smaller than or equal to 1 mm. The
use of initial tubes for further drawing having a wall thickness
in excess of 1 mm, such as 44 by 2 mm, or 44 by 1.65 mm, has not
been known. Large coils with a unit weight of 400 to 1500 kg are
obtained depending on the outside diameter and the wall thickness
of the initial tubing.
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The large coils can be stored intermediately and shipped
immediately after their manufacture to a second production plant,
using suitable transportation means. The large coils are stacked
on suitable transportation or shipping racks, with three to six
large coils per rack. The transportation racks with the large
coils are then loaded via lifting gear on the loading bed of the
transportation vehicle, for example a flat-bed truck, and
transported to the final manufacturing site. So-called spiders
can be employed as transportation racks, on which the large coils
are stacked in lying positions, i.e. in a horizontal arrangement.
Alternatively, several large coils can be welded as a composite
into a shrunk-on foil, which are loaded and stored horizontally
on flat pallets. According to another variation, the large coils
are loaded in upright positions on prism-like pallets, which can
be provided with a felt lining.
The further processing of the large coils into finished
tubes can be carried out either directly from the transportation
means, or via a facility for intermediate storage. Further
processing of the large coils transported to the production site
is carried out on commonly employed continuous drawing machines.
If the large coils are transported on spiders, the spiders serve
as transporting, storing and/or unwinding means. If the large
coils are transported to the production plant loaded lying
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horizontally on spiders or flat pallets, the racks with the large
coils can be placed on a lowerable take-off table, located
directly in front of the unwinding or take-off reel. The leading
end of
the uppermost large coil is then positioned at the required
working level by lowering the take-off table.
It is also possible to remove the large coils from the racks
individually and to transport them to the drawing machine with a
fork-lift truck. The leading end of the coil is then fed to a
separate take-off device by an inside gripper device. This
variation permits pointing of the leading end of the coil as the
preceding coil is being drawn, and the construction of the
unwinding reel can be simplified. Auxiliary time periods required
for these working steps can thus be shortened. It may also be
possible to adjust the large coils to a "soft~~ state of strength
by an additional heat treatment carried out prior to the final
drawing process.
The proposed production procedure offers the advantage that
the production equipment for manufacturing the initial tube
products can be utilized at full capacity. Large coils can be
produced very inexpensively, which then can be sold to third
parties as intermediate products. The final producer then only
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needs a continuous drawing machine with the usual additional gear
and equipment for producing tubing with the desired dimensions.
The benefits gained from the particularly economical centralized
production of the initial tubing outweigh the additional
transportation costs. Since the large coils are already drawn to
a wall thickness of 1.5 to 4.0 mm, one draw can usually be
omitted in the final production.
A suitable intermediate transportation rack is a metal
spider. The use of spiders for coils of tubing wound has not been
known heretofore. The proposed tube construction of the spiders
makes it possible to stack the spiders as empties, and it is
possible to stack at least three spiders into each other. This
ensures inexpensive shipping of the empty spiders. So as to
completely exclude slipping of the large coils from the spider in
the course of transportation, the intermediate space between the
shaft of the spider and the inner side of the large coils can be
compensated by an inflatable air cushion element. According to
another variation, the large coils are locked by a spreading
device that can be secured on the shaft.
The spiders also offer an advantage in that the initial
copper tubing, which is wound in layers for further processing,
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can run off the spider directly without first having to unstack
the coils from the spider.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and features of the present invention will
become apparent from the following detailed description con-
sidered in connection with the accompanying drawings. It is to
be understood, however, that the drawings are designed as an
illustration only and not as a definition of the limits of the
invention.
In the drawings, wherein similar reference characters denote
similar elements throughout the several views:
FIG. 1 shows a top view of a spider for large coils;
FIG. 2 is a front view of the spider according to FIG. 1;
and
FIG. 3 is a perspective view of a large "LWC~~ coil.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in detail to the drawings, at a central
manufacturing plant, in a prefabricating line consisting of a
conventional extruder press and a continuous drawing machine,
initial tubing with an outside diameter of 50 mm and a wall
thickness of 3 mm is pressed by extruding copper billets. This
tubing is processed further by subsequently drawing it in one
drawing step into initial tubing with dimensions of 44 by 2 mm.
The initial tubing is then wound layer to layer on a conventional
winding machine into a large LWC-coil with an outside diameter of
2175 mm and an inside diameter of 1250 mm, with a winding height
of 350 mm. The large coil has a weight of 1000 kg and the length
of the wound tubing material amounts to 426 meters per large
coil. Five (5) large coils are horizontally stacked on each
spider. The flatbeds of a truck with trailer are loaded with 5
spiders each carrying 5 large coils. The large coils are shipped
in this way from the central manufacturing location to the
various processors of the tubing.
At the location where the tubing is processed further, the
spiders are unloaded from the truck by fork-lift trucks,
transported by a chain conveyor to a lifting table, and deposited
upright on the table. The lifting table lowers the spider by
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about 400 mm, placing it on receiving forks. The forks then drive
the spider over the unwinding reel. The reel crown takes over the
spider by lifting it up, and the forks drive back into their
starting positions. The take-off reel or take-off table is
lowered by about 2 meters until the uppermost coil is positioned
at the level of the draw-in line. The leading end of the tubing
of the uppermost coil is positioned at the working level and the
required tangent is attached.
The take-off reel is designed for a circumferential take-off
speed of up to 100 m/min. The speed is synchronized between the
take-off reel and the continuous drawing machine. The leading end
of the tubing is inserted in the bending apparatus and fed to the
pointing unit, which is filled with the lubricant and where the
mandrels are set and the pointing is carried out. Thereafter,
the leading end of the tubing is inserted in the driving
apparatus and fed to the drawing machine.
On the drawing machine, a tubing with the dimensions 42 by
1.5 mm is drawn by one draw from the 44 by 2 mm initial tubing
material, and then placed in a basket, which is transported to
the next drawing machine downstream in order to carry out the
next production draw. As the next-following coil is being taken
off, the take-off table is continuously driven to the top at a
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rate depending on the take-off speed, so that the unwinding
tubing is always positioned at the working level. After all coils
have been taken off from the spider, the spider is removed from
the take-off table, and another loaded spider is driven to the
take-off table in the manner described above.
According to another embodiment, the spiders are unstacked
at the tube processor's plant as the final producer, and the
large coils are loaded on a stationary take-off reel one after
the other. This simplified variation permits separate pointing of
the leading end of the tubing of the individual large coils as
the preceding large coil is being drawn. The large coils are
unstacked from the spider in this connection directly in front of
the take-off reel.
According to a third embodiment, the large coils are shipped
for further processing on prism-like pallets. The prism pallets
are lifted from the truck and subsequently unstacked, and the
large coils are then transferred to the chain conveyor already in
the form of singled units.
All other working steps are carried out analogous to the
procedure explained above.
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FIG. 3 shows a large LWC coil 9. Coil 9 may also consist of
a 44 by 1.65 mm tubing wound in layers, with an outside diameter
OD of 2300 mm and an inside diameter ID of 1250 mm, as well as
with a height H of 350 mm. The wound length of such a large coil
amounts to 512 mm. The LWC coil has a weight of 1000 kg. Several
of such large coils 9, for example five, are stacked on a spider
according to the type of construction shown in FIGS. 1 and 2.
The spider consists of a bottom part 1 and a centrally arranged
shaft 2 in the form of a welded tube construction. The bottom
part 1 is formed by an inner ring 3 and an outer ring 4, which
are connected with one another via the tubular pieces 5 arranged
in the form of spokes. Four tubes 6 are vertically secured on the
inner tube 3 and equally spaced from each other. At their top
ends, the four tubes are connected with one another crosswise by
the tubular bridges 7. The length and height of the tubes 6
depend on the number of large coils to be stacked on the spider.
The spiders are built very stable because they have to be capable
of receiving loads of this type weighing up to 7 tons. The
constructional design of the spiders makes it possible to stack
such spiders as empties one into the other. The individual
spiders are fitted one into another by turning them by a defined
angle about the center axle, so that the bottom parts 1 of the
spiders rest one on top of the other.
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For securing the large coils 9 stacked on the spiders
during transport on a vehicle, the following possibilities are
available: A spreading device is secured on shaft 2 of the
spider, by which the individual spiders are locked in their
positions. According to another variation, an inflatable air
cushion may be arranged around shaft 2 of the spider, which, upon
inflation, fills the intermediate space between shaft 2 and the
inside 10 of the large coil 9 at least partially, so that
slipping of the large coil 9 during transit is excluded.
Accordingly, while only a few embodiments of the present
invention have been shown and described, it is obvious that many
changes and modifications may be made thereunto without departing
from the spirit and scope of the invention.
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