Note: Descriptions are shown in the official language in which they were submitted.
sackground of the Inventi _
The invention relates to a method for rolling a tube
to a smaller diameter, in which at least one area of the
outside of the tube is brought into contact with at least one
roll that is rotatable around its axis, whereby said roll
and the tube are brought into relative movement with respect
to another. The contact surface of the roll and the tube,
considered between -two planes spaced in the longitudinal
direction of the tube, lies at an angle to the longitudinal
axis of the tube.
U.S. Patent No. 3,354,682 teaches production of a
truncated pyramid shaped tube by means of an internal,
truncated pyramid shaped mandrel placed in a cylindrical
starting tube, :in combination with two eccentric rolls, of
which the rotational axis is perpendicular to the longitudinal
direction of the tube. The roll surfaces comprise a triangular
groove which delimit together the square cross section. In
addition to being eccentric, the rolls also include an
interrupted roll surface, so that the total roll length is
limited to the effective developed length of the circumference
of the roll.
This has the disadvantage, that for tubes of different
length and diameter, other rolls and other mandrels are
required which increases labour, necessitates a large capital
investment in rolls and mandrels, and makes economic operation
difficult.
Substantially conical tubes, used for example as light
standards or ship masts, are generally known. U.K. Patent
Specification No. 1,099,182, for example, teaches a conical
tapering metal ship mast which is produced by rolling a metal
plate and folding the plate in -the longitudinal direction.
The slot in the profile formed however necessitates a seal.
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Also, stepped tapering light standards are known, in
which tube shaped parts of differing diameter are welded
together by means of reducers disposed interjacent each part.
These known methods have several disadvantages apaxt
from the already indicated necessity of the extra steps of
welding or sealing. In particular there is the risk that
the welds or seams will corrode or degrade and therefore
shorten the product life.
Summary of the Invention
rrhe object of the invention is overcoming these
disadvantages and providing a method and device with which
very long tube lengths of tapering diameter can be rolled,
without the necessity of using internal mandrels or inter-
changing rolls.
In one particular aspect the present inven-tion provides
; a method of rolling elongated tube to a smaller diameter
without the use of an internal mandrel comprising the steps
; of contacting the exterior of the tube with the forming ~;
surface of at least one roll rotatably driven about an axis
lying at an angle to the direction of elongation of the tube
to provide circumferential and longitudinal movement of the
` tube with respect to the roll for causing the forming surface
to roll the tube to a smaller diameter.
In another particular aspect the present invention
` provides an apparatus for rolling elongated tube to a smaller
diameter without the use of an internal mandrel comprising:
at least one roll having a forming surface for contacting
the exterior of the tube. said roll being rotatable about an
axis lying at an angle to the direction of elongation of the
tube;
means for adjusting the position of said roll normal to
the direction of elongation of the tube to obtain the
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contact; and
drive means for rotating said roll about said axis, the
contact of the rotating roll with the exterior of the tube
providing longitudinal and circumferen-tial movement of the
tube with respect to the roll for causing said forming
surface to roll the tube to a smaller diameter.
Description of the Drawings
The invention will now further be elucidated referring
to the accompanying drawings of some exemplified embodiments.
Fig. 1 shows schematically a side view of a device for
performing the method according to the invention.
Fig. 2 shows a plane view of the device according to -
Fig. 1.
Fig. 3 shows a schematic side view of an alternate
embodiment of the device according to Fig. 1, and more
specifically a device for adjusting the rolls.
~, Description of the Preferred Embodiments
Referring particularly to Figs. 1 and 2 of the drawings,
starting material in the form of a length of round cylindrical
tube 1 is employed, preferably of steel, which is rolled in the
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device without any internal mandrel to a conical tube 1', of
diameter smaller than that of the starting tube 1.
The tube 1 is led through a heating unit 2, with which
the tube is brought to the rolling temperature. After leaving -
~` the heating unit 2, two cylindrical, disk shaped, rotary driven
rolls 3, 4 contact the tube 1, which roLls have been mounted
at both sides of the tube. The axis of rotation AL of the
rolls each make an angle ~ with the longitudinal axis HL of
the tube, which angle ~ is in this embodiment smaller than
90. The contact surfaces of the rolls 3, 4 with the outer
circumference of the tube 1 are preferably each on a separate
helical line with the cylindrical rolled tube, i.e. on a spaced
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spiral with the conical rolled tube, so -that each of the rolls
causes a part of the total deformation. In the drawings it
can be seen that from the starting diameter the rolls have
already moved over some distance of the tube 1 symmetrically
to each other, as a result of which a shoulder 5 has formed,
which is rolled out. The rolls 3, 4 each rotate with a number
of revolutions Nl around their axes AL, so that the tube 1, 1'
rotates with a number of revolutions N2 and becomes gradually
smaller, as the rolls 3, 4 move closer to the longitudinal
axis HL. For support of the rolled tube 1', a set of conical
support rolls 6 are provided.
In Fig. 3 an embodiment is shown of the adjusting devices
for the rolls 3, 4, which are symmetrical so that only one
oE these adjustin~ devices is illustrated. The rolls 3, 4
are associated with carriers 7, 8 which are movable to and
from the longitudinal axis HL by disp:Lacement means (not shown).
The carrier 8 has been provided with a support 9 provided at its
end with a pivot shaft 10, around which a carrier 11 of a roll
drive motor 12 can pivot. This roll drive motor 12, which is
for example electrically or hydraulically driven, is operatively
associated with the roll 4 by means of shaft 13. The roll drive
motor 12 has been provided at its other end with a support 14
provided at its end with a pivot shaft 15 on which the piston
rod 16 of a piston-cylinder unit 17 is mounted. Unit 17 is
controlled by means of the supply and exhaust lines 18, 19 and
the valves 20, 21 so that the piston rod 16 is selectively
extensible or retractable. At its other end the piston-
cylinder unit 17 is fastened to the carrier 8 by means of
pivotable assembly 22, 23, 24. By -the operation of the piston-
cylinder unit the position of the roll 4 and thereby theangle ~ can be changed, whereas by the selectlve displacement
of the carrier 8 the roll can be moved closer -to the
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longitudinal axis HL or further away therefrom.
Instead of providing rotary drive to the rolls 3, 4,
the tube 1 can be rotary driven, whereby the rolls 3, 4 can be
freely rotatable around their axes, in which case a pull
force K is applied to tube 1.
~2~
Although with the device according to the invention
round tube, preferably from steel, is processed -to conical
tube or cylindrical tube with conical parts, such as adapted
for use as light mast, it is evident that also other metals
and/or other materials, such as for example synthetic materials
could be processed.
The invention is not limited to the sho~n and/or
described embodiments but covers all variations thereo~.
