Note: Descriptions are shown in the official language in which they were submitted.
~300359
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an apparatus for
fabricating multi-layer spiral tubes which are available as
pressure-resistant large-diameter steel pipes for piping or
cylindrical drums for columns, tanks, heat-exchangers or the
like.
Descri~tion of the Prior Art
Large-diameter high-pressure steel pipes for pipe-line
use are associated with great difficulties in transportation
because they are frequently used in areas inconvenient to
access. Furthermore, pipes of long dimensions having a
. pressure-resistance in performance and moreover being
excellent in the degree of roundness and of high precision
such that a dimensional error such as misalignment at weld
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13003S9
l joint portions is small, are required in the construction
industry.
The large-diameter welded steel pipes in the prior art
are generally classified into single-layer pipes and
multi-layer pipes. The single-layer pipes are
sub-classified into those called UO tubes formed by rolling
a sheet and having a straight weld joint along their
longitudinal direction and spiral tubes having a spiral weld
joint, and the multi-layer pipes are sub-classified into
those of swirl type or concentric circle type and those of
spiral type in which a web is wrapped spirally around an
inner cylinder or inner tubes.
An outline of an apparatus for fabricating multi-layer
spiral tubes in the prior art is shown in Figs. 3(a) and
3(b). In these figures, a web 01 delivered from a
coil-shaped web 01a is wrapped around a rotating inner
cylinder 018 supported by a supporting device 017 with the
aid of a wrapping device 014. For this inner cylinder 018,
normally the UO tube is used. On the feed device for
~ delivering the web 01, a leveler 010, a sheet-jointing
welding machine 05, pinch rolls 03, a heating device 013 and
the like are provided. In the wrapping device 014 a welding
machine 015 and a grinding machine 016 are provided. Hence,
after the side edge portions of the web 01 wrapped around
the inner cylinder 018 have been butt-welded with each
other, the welded places are ground to form a spiral tube.
On the other hand, an outline of an apparatus for
fabricating single-layer spiral tubes known in the prior art
is shown in Fig. 4. With reference to this figure, a
coil-shaped web 01a is delivered by pinch rolls 03 via a
13(~0359
1 leveler 010. I~ is then bent by means of bending rolls 04,
and adjacent side edge portions of a web 01 are welded
together by means of an inner surface welding machine 06 and
an outer surface welding machine 07 while maintaining the
cylindrical shape of the bent web 01 by means of inner
surface guide rolls (not shown) and outer surface guide
rolls (not shown). The thus formed tubular body is received
by a receiving roll (not shown) to be sent in the direction
of an arrow indicated in Fig 4, and after it is cut into a
predetermined dimension, a spiral tube 02 is completed. It
is to be noted that the web 01 delivered from the
coil-shaped web 01a has its side edge portions to be welded
together machined by a side trimmer 08 and an edge preparing
machine 09 and can be successively jointed by the
sheet-joining welding machine 05, and therefore, fabrication
of long tubes is possible.
Among the heretofore known tubular materials, the UO
tubes and the multi-layer tubes of swirl type or concentric
circle type have shortcomings in that their fabrication to
long dimensions is limited and even if they were to be
lengthened by jointing through circumferential welding they
would be expensive.
On the other hand, the multi-layer tubes of spiral type
also have similar shortcomings to the above-described ones
in that since the UO tube is used as the inner cylinder, the
fabrication of the tube to long dimensions is limited. In
addition, in the case of the single-layer spiral tubes in
the prior art, although fabrication of long dimension tubes
is possible by jointing the webs, they were solely used for
general structures and believed to be inadequate for
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13V0359
1 pressure-resistant steel pipes due to the fact that in
addition to a poor degree of roundness, a dimensional error
caused by misalignment at the spiral weld portions was
large.
Even if the pressure-resistant steel pipes such as the
above-described multi-layer tubes were successively jointed
through circumferential welding in a factory to increase
their length dimension, transportation of them was difficult
because the location of the constructing of a pipe-line was
a remote area. Hence, increasing their length had to be
done at the field of construction by circumferentially
welding short tubes, and thus they had shortcomings in that
it was not easy to obtain long-dimension pressure-resistant
steel pipes of satisfactory quality and the cost of
construction would become high.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to
provide an improved apparatus for fabricating multi-layer
spiral tubes, which has a simple structure and yet is free
from the above-described shortcomings of the fabricating
apparatus in the prior art.
A more specific object of the present invention is to
provide an apparatus for fabricating multi-layer spiral
tubes, which can be disposed at the field of construction of
a pipe-line and can fabricate pressure-resistant spiral
tubes of excellent quality, and yet which has a simple
structure.
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13003S9
1 According to one feature of the present invention,
there is provided an apparatus for fabricating multi-layer
spiral tubes, which comprises: a wrapping drum supported at
its one end by a chuck of a drive mechanism so as to be
S rotatable around a horizontal axis; a take-up drum coupled
with another drive mechanism for translation and rotation
thereof, having the same diameter as said wrapping drum,
being movable in the direction of the axis of said wrapping
drum, and being rotatable around the common axis at the
position opposite to said wrapping drum; a web feed dPvice
for the first layer for spirally feeding the web on said
wrapping drum with the leading end of the web fixedly
secured on said take-up drum; a wrapping device for the
first layer web for wrapping the web fed through said web
feed device for the first layer on said wrapping drum,
depessing the web thus wrapped, and jointing by welding the
adjacent side edge portions of the wrapped web to form a
spiral tube of the first layer; web feed devices for upper
layers provided adjacent the side of the take-up drum of
said web feed device for the first layer for spirally
feeding the webs on the spiral tubes of the lower layers so
as not to make the welding lines of the upper and lower
layers coincident with each other; and wrapping devices for
upper layer webs for spirally wrapping the webs thus fed on
the spiral tubes of the lower layers, depressing the webs
thus wrapped, and jointing by welding the adjacent side edge
portions of the wrapped webs to form spiral tubes of the
upper layers.
In operation, the leading end of the web of the first
layer is fixedly secured to the take-up drum at a
13~035g
1 predetermined wrapping angle, and the wrapped web is taken
up by the take-up drum. This take-up drum is movable along
its axial direction on a floor, and it performs a take-up
operation by moving in a direction going away from the feed
side of the web while rotating at the wrapping speed, that
is, at the speed of welding the adjacent side edge portions
of the web wrapped in a spiral manner.
On the other hand, the wrapping drum having its outer
circumferential surface as a precise circular cylinder is
not moved in its axial direction, but the web is wrapped
therearound while it is rotated at the same speed as the
take-up drum. Backing is effected for its side edge
portions from its inner surface by means of the backing
section of the wrapping drum. One side welding is effected
from its outer surface on the opposite side to the backing
section to form a full penetration weld portion.
In such a way, the wrapped and welded web forms a
'~ spiral tube, which in turn is drawn out of the wrapping drum
by moving the take-up drum in the direction away from the
web feed device.
The webs of the upper layers are fed at the wrapping
angle parallel to that of the first layer web on the
above-described spiral tube from the web feed devices for
the upper layers disposed adjacent the web feed device for
the first layer, and the wrapping devices for the upper
layer webs wrap the upper layer webs around the said spiral
tube, depress the webs thus wrapped, and are joined by
welding the adjacent side edge portions of the upper layer
webs to form the upper layer spiral tubes, thereby the
V359
1 long-dimension spiral tubes wrapped in a plurality of layers
being continuously fabricated.
The above-mentioned and other objects, features and
advantages of the present invention will become more
apparent by reference to the following description of
preferred embodiments of the invention taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING,S
In the accompanying drawings:
Fig. l(a) is a plan view of an apparatus for
fabricating multi-layer spiral tubes according to one
preferred embodiment of the present invention;
Fig. l(b) is a side view of the same apparatus;
Fig. 2(a) is an enlarged partial cross-sectional view
showing an inner structure of a backing section of a
wrapping drum;
Fig. 2(b) is a transverse cross-sectional view taken
along line B-B in Fig. 2ta) as viewed in the direction of
arrows:
Fig 3(a) is a schematic view of an apparatus for
fabricating multi-layer spiral tubes in the prior art;
Fig. 3(b) is a perspective view of a principal part of
the same apparatus; and
Fig. 4 is a schematic view of an apparatus for
fabricating single-layer spiral tubes in the prior art.
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13()0359
1 DESCRIPTION OF THE PREFERRED EMBODIMENTS
A plan configuration of an apparatus for fabricating
multi-layer spiral tubes according to one preferred
embodiment of the present invention is shown in Fig. l(a),
and a side configuration of the same apparatus is shown in
Fig. l(b). Referring to these figures, a chuck 3a is
mounted via a shaft 12a to a drive mechanism 2a disposed on
a floor 39, and a wrapping drum 4 is mounted to this chuck
3a so as to be rotated by the drive mechanism 2a. The chuck
3a can be adjustably moved in the radial direction so as to
be adapted to different outer diameters of the wrapping drum
4 similar to the conventional chuck for use in a machine
tool. A web feed device C1 for the first layer is provided
opposite the side of the wrapping drum 4, and the web 30b is
fed from coiled web 30a to the wrapping drum 4 at a certain
angle. At a wrapping position for a web 30b, a frame 8 for
wrapping is disposed on the floor 39, and on this frame 8
are equipped a group of depressing rolls 27, a group of
supporting rolls 28, an automatic welding machine 9, a laser
gap sensor 10 and an automatic magnetic defect hunter 11.
The group of depressing rolls 27 and the group of supporting
rolls 28 are rotatably supported so that the directions of
the respective rolls can be varied in accordance with
variation of a wrapping angle, i.e., a feed angle of the web
30b. A wrapping device A1 is comprised of the drive
mechanism 2a, the wrapping drum 4, the frame 8 and the
above-mentioned other component members. Toward the right
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1300359
1 as viewed in Figs. l(a) and l(b) away from the end of the
wrapping drum 4, there are provided web feed devices C2 and
C3 for upper layers, i.e., second and third layers, and, in
combination with each of these web feed devices, there are
provided wrapping devices A2 and A3 comprised of the same
components as the wrapping device A1.
On the floor 39 are a rack 36 and rails 37 extending
parallel to the axis of the wrapping drum 4. Another drive
mechanism 2b is placed on the rails 37 via wheels 16. The
drive mechanism 2b can be moved along the rails 37 by the
meshing of a pinion (not shown) that is rotated by a motor
(not shown) assembled in the drive mechanism 2b with the
rack 36 on the floor 39.
One end of a take-up drum 6 is supported by a chuck 3b
that is fixedly secured to a shaft 12b of the drive
mechanism 2b. This chuck 3b also can be adapted to adjust
to variation of the outer diameter of the take-up drum 6
similar to the chuck 3a and the wrapping drum 4. In Fig.
l(a), the take-up drum 6 has such a length that its tip is
brought into contact with the end surface of the wrapping
drum 4 when the chuck 3b is moved leftward as viewed in Fig.
l(a) until being closest to the wrapping device A3.
Furthermore, the take-up drum 6 is provided with a fixing
device 7, and upon commencement of wrapping of the web 30b,
the leading end of the web 30b is fixedly secured to the
take-up drum 6 by means of the fixing device 7. The outer
diameter of the take-up drum 6 is the same as that of the
wrapping drum 4. The take-up drum 6 is rotated at the same
speed as the wrapping drum 4 is as driven by the drive
mechanism 2b. A drawing device B is comprised of the
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1300359
l above-described rails 37, drive mechanism 2b and chuck 3b
and other component members.
A feed table 17 for feeding the web 30b to the wrapping
drum 4 is placed on arcuate rails 24a and 24b dispased on
the floor 39. On this feed table 17 are disposed drive
mechanisms 18a and 18b, a pay-off reel 19, a leveler 20, a
sheet jointing welding machine 21, pinch rolls 22 and a
heater 25. The web 30b is fed from a coil 30a charged on
the pay-off reel 19 through the leveler 20 and the pinch
rolls 22 to the wrapping drum 4 and the wrapping device A.
The feed table 17 can be moved on the arcuate rails 24a and
24b in the left and right directions as viewed in Figs. l(a)
and l(b) by meshing between pinions not shown which are
mounted within the drive mechanisms 18a and 18b,
lS respectively, and the above-described arcuate racks 23a and
23b disposed on the floor 39, so that the feed angle of the
web 3Ob can be varied.
The heater 25 is equipped with an electric resistance
heat generator (not shown) which is divided into a plurality
of heat generator sections along the widthwise direction of
the web 30b that is fed to pass thereover, and the
respective heat generator sections can be adjusted to have
different heat generating rates by phase-controlling the
magnitude of the electric current by means of a thyristor.
In this connection, it is also possible to dispose a
plurality of gas burners in place of these electric
resistance heat generator sections and to control the
combustion rates of the respective gas burners. A feed
device C1 for the first layer web is comprised of the
above-described arcuate rails 24a and 24b, feed table 17,
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13~)0359
1 and other component members. The web feed devices C2 and C3
for the second and third layers respectively are comprised
similarly to the web feed device Cl for the first layer, and
feed the webs 40b and 50b from the coiled webs 40a and 50a
to the corresponding wrapping devices A2 and A3
respectively. The wrapping device A2 wraps the web 40b on
the spiral tube fabricated from the web 30b, and welds the
same to fabricate the spiral tube of the second layer, while
the wrapping device A3 fabricates the spiral tube of the
third layer in the similar way.
The above-mentioned wrapping devices Al through A3,
drawing device B and feed devices Cl through C3 are all
coupled to a central control unit 1 containing a
micro-computer therein, and provision is made such that the
central control unit 1 momentarily achieves arithmetic
processing by means of the micro-computer on the basis of
preliminary input operation and detection data input from
sensors or the like associated with the respective devices
A, B and C, and issues operation commands to the respective
devices, and thereby the respective devices can perform
appropriate operations.
The inner structure of the above-described wrapping
device A is shown in an enlarged scale in Figs. 2(a) and
2(b). Referring to these figures, to the end of the
wrapping drum 4 is fixedly secured a backing section 5
having a cylindrical shape and made of copper. Both the
wrapping drum 4 and the backing section 5 have the same
outer diameter, and their outer circumferential surfaces are
formed with a minute taper so that the spiral tube formed by
wrapping and welding the web 30b can be easily drawn as
1300359
1 sliding along the outer circumferential surfaces in their
axial direction. A water-cooling jacket 34 is provided on
the inside of the backing section 5, and the water-cooling
jacket 34 is connected through distribution pipes 31 to a
water-feed/drain outer tube 13b. A drain outer tube 13a,
the water-feed/drain outer tube 13b and a water-feed inner
tube 14 form a double tube structure. The drain outer tube
13a is fixedly secured to the drive mechanism 2a, then it
penetrates through the interior of the shaft 12a as
supported by bearings (not shown) and extends up to the
interior of the wrapping drum 4. The drain outer tube 13a
communicates with a drain piping (not shown) through a drain
nozzle 15, while the water-feed inner tube 14 communicates
with a water-feed piping (not shown). The fixed drain outer
tube 13a and the rotatable water-feed/drain outer tube 13b
are coupled with each other by means of a rotary joint 32,
and thereby leakage of coolant drain water is prevented.
The interval between the water-feed inner tube 14 and the
drain outer tube 13a is assured by means of spacers 38, so
that coolant drain water can easily flow through the
passageway between these tubes 14 and 13a. Between the tip
end portion of the water-feed inner tube 14 and the
water-feed/drain outer tube 13b, a gland packing 33 is
equipped as a provision for preventing the feed coolant
water from flowing into the drain passageway. Accordingly,
coolant water feed from a water-feed piping (not shown) is
fed into the water-cooling jacket 34 through the water-feed
inner tube 14, the water-feed/drain outer tube 13b and the
distribution pipes 31. After it has cooled the backing
section 5, it passes through the distribution pipes 31, the
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13()03S9
1 water-feed/drain outer tube 13b, the drain outer tube 13a
and the drain nozzle 15, and thereafter it is drained
through a drain piping (not shown).
It is to be noted that a cylindrical body made of
ceramics can be used as the backing section 5 in place of
the cylindrical body made of copper, and in this modified
embodiment, since cooling can be achieved by air-cooling,
the above-described members for water-cooling such as the
water-cooling jacket 34, the distribution pipes 31, the
drain outer tube 13a, the water-feed/drain outer tube 13b,
the water-feed inner tube 14 and the like would become
unnecessary.
Upon fabricating a spiral tube, at first the take-up
drum 6 is moved leftwards as viewed in figs. l(a) and l(b)
until it comes into contact with the backing section 5.
Subseguently, the desired inner diameter dimension of the
spiral tube, that is, the desired outer diameter dimension
of the wrapping drum 4 and the take-up d~um 6, the outer
diameter dimensions of the spiral tubes fabricated from the
webs 30b and 40b, the width dimensions of the webs 30b, 40b
and 50b, and the desirable gap dimension between the side
edges of the webs 30b, 40b and 50b are input to the central
control unit 1 to the drive mechanisms 18a and 18b in the
respective feed devices C1, C2 and C3 on the basis of the
results of calculation to move the respective feed tables
17, and thereby the angle of feeding of the webs 30b, 40b
and 50b from the feed devices Cl, C2 and C3 with respect to
the direction of the axes of the wrapping drum 4, backing
section 5, take-up drum 6, and spiral tubes fabricated from
the webs 30b and 40b, that is, the wrapping angle as well as
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~3~0359
1 the orientations of the depressing roll group 27 and the
supporting roll group 28 can be adjusted.
Thereafter, the coils 30a, 40a and 50a are charged in
the pay-off reels 19, and after the web 30b has, at first,
been flattened by the leveler 20, it is fed to the wrapping
device A1 by the pinch rolls 22. The tip end of the fed web
30b is fixedly secured to the take-up drum 6 by means of the
fixing device 7. The take-up drum 6, the wrapping drum 4
and the backing section S are rotated at a predetermined
wrapping speed that is equal to a predetermined welding
speed, and the web 30b is wrapped around these drums and is
depressed by the depressing roll group 27. As the take-up
drum 6 moves in the rightward direction as viewed in Figs.
l(a) and l(b), and when the fixing device 7 has passed over
the supporting roll group 28, the supporting roll group 28
is jacked up to a predetermined height to make them support
the wrapped web 30b.
Then, when the drums have made one revolution from
their initial position for wrapping and a welding gap has
been formed between adjacent side edge portions of the web
30b, welding is commenced by the automatic welding machine
9, and after one further revolution, reliability of the
welded location is confirmed by means of the automatic
magnetic defect hunter ll. At this moment, since the welded
location of the side edge portions of the web 30b is backed
by the outer circumferential surface of the backing section
5, drop of weld caused by deep weld penetration can be
prevented. In addition, during the wrapping of the web 30b,
the gap dimension between the adjacent side edge portions of
the web 30b is monitored by the laser gap sensor lO and the
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1 monitored data are input to the central control unit 1.
Hence, if the monitored gap dimension is about to exceed a
dimensional tolerance, the central control unit l analyzes
the data by means of the micro-computer, converts them into
signals and issues commands to the drive mechanisms 18a and
18b and the heater 25 in the feed device Cl. If the gap
dimensions become close to the upper limit of the tolerable
range, then the wrapping angle is changed by slightly moving
the feed table 17 in the rightward direction as viewed in
Figs. l(a) and l(b), resulting in an increase of the tension
in the left side portion of the web 30b as viewed in Figs.
l(a) and l(b). Also the heat generator sections (not shown)
in the left side portion of the heater 25 as viewed in Figs.
l(a) and l(b) are made to generate heat and thus the wrapped
web 30b is made to have a temperature gradient in its
widthwise direction to be bent slightly, and thereby the
above-mentioned gap dimension is narrowed. On the contrary,
if the gap dimension becomes close to the lower limit of the
tolerable range, the operation opposite to that described
above is carried out. In this way, while the gap dimension
is always maintained within the tolerable range,
simultaneously with wrapping of the web 30b, the side edge
portions of the web 30b are constrained under pressure by
the depessing roll group 27, and are welded together to form
a spiral tube.
On the other hand, the drawing device B moves the
take-up drum 6 in the rightward direction as viewed in Figs.
l(a) and l(b) at a speed of one pitch (of the spiral of the
wrapped web) per revolution while rotating the take-up drum
6 at the same speed as the wrapping speed, and thus it draws
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13~03S9
1 the formed spiral tube from the wrapping drum 4 and the
backing section 5.
When the fixing device 7 on the take-up drum 6 has
passed over the wrapping device A2 for the second layer
rightward as viewed in Figs. l(a) and l(b), the tube
fabrication work of the web 30b is temporarily stopped, the
tip of the web 40b for the seco~d layer is fixed to the
outer surface of the first layer spiral tube by welding or
other means with the welding lines of the first and second
layers mutually offset, and then the web feed devices Cl and
C2 as well as the wrapping devices Al and A2 are driven with
the same pace to concurrently fabricate the first and second
layer spiral tubes. Subsequently, when the tip of the web
40b has passed over the wrapping device A3 for the third
layer rightward as viewed in Figs. l(a) and l(b), the tube
fabrication work is again temporarily stopped, the tip of
the web 50b for the third layer is fixed to the outer
surface of the second layer spiral tube by welding or other
means with the welding lines of the first, second and third
layers mutually offset, and then the web feed devices Cl, C2
and C3 as well as the wrapping device Al, A2 and A3 are
driven with the same pace to concurrently fabricate the
first, second and third layer spiral tubes.
In this way, the webs 30b, 40b and 50b are continuously
wrapped in a spiral form and welded, and when any of the
coils 30a, 40a and 50a has been entirely used, fabrication
of the tube is once stopped, another coil 30a, 40a or 50a is
newly charged in the pay-off reel 19, the lead end of the
new web 30b, 40b or 50b is jointed to the trailing end of
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~3(~0359
l the last web 30b, 40b or 50b by means of the welding machine
21, and again the tube fabrication work is commenced. Then,
the formed spiral tube is cut into desired lengths, and
after edge preparation for circumferential welding has been
done, a multi-layer spiral tube is completed.
In the above-described tube fabrication work, it is
possible, if necessary, to support the outermost layer of
the multi-layer spiral tube fabricated by the wrapping
device A3 by the rail 37 beneath the spiral tube and the
truck for supporting the receiving rollers moving on the
rail 37.
If the apparatus for fabricating multi-layer spiral
tubes according to the present invention is used, owing to
the fact that a web is wrapped around a wrapping drum whose
lS outer circumferential surface is machined into a precise
circular cylinder, a degree of roundness of the fabricated
spiral tube is improved, and also owing to the fact that a
plurality of web feed devices and wrapping devices are
installed adjacent the direction of delivery of the
fabricated tubes and the outer layer tubes are sequentially
fabricated on the circumference of the lower layer tubes, it
is possible to obtain a long-dimension multi-layer spiral
tube. In particular, by installing the apparatus according
to the present invention at the field of construction, the
circumferential joints formed by all-attitude welding having
low reliability can be reduced to a minimum, and hence a
reduction in expenses can be achieved. In addition, owing
to the fact that a web coil of high precision making little
zig-zag movement is used and the gap between the side edges
of the web can be adjusted by manipulating the laser gap
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1 sensor, the feed table and the heater, the side trimmer
which was used in the apparatus in the prior art becomes
unnecessary. Still further, owing to the face that, for the
lowermost layer spiral tube, the portions of the web to be
welded are welded by a large current while backing the
portions with the backing section to give sufficient weld
penetration, an I-shaped weld beveling suffices and an edge
preparating machine becomes unnecessary. In addition, a
multi-layer spiral tube can be fabricated at a single stroke
with high efficiency, and fabrication of a long-dimension
multi-layer spiral tube as compared to a multi-layer tube of
the inner cylinder type in the prior art, is possible.
Since many changes and modifications can be done to the
above-described construction without departing from the
spirit of the present invention, it is intended that all
matter contained in the above description and illustrated in
the accompanying drawings shall be interpreted to be
illustrative and not as a limitation to the scope of the
invention.
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