Note: Descriptions are shown in the official language in which they were submitted.
2~
Peter WEICHH~RT, La~dertsham lO,
Austria
Process and machine for the forming of metal tubes into
conical or tapered bodies
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The invention concerns a process for the working of
metal tubes into conical or tapered bodies, in which the
metal tube blank is worked by a pair of rolls engaging
and rolling the tube exterior, each of said rolls exhibit-
15 ing on their working surface a groove of a cross section
corresponding to half the cross-sectional shape of the
tube blank, said groove being tapered in the circumfe-
rential direction. Furthermore, the invention concerns a
machine for performing this process.
Metal tubes with, for example, a circular cross section
are formed into conical bodies while at the same time un-
dergoing elongation, particularly for use as masts, lamp
poles, flag poles and similar.
In order to achieve a uniform taper with as round a cross
section as possible, it is necessary in the case of the
known processes and machines to process exclusively seam-
less metal tubes. The manufacture of conical bodies of
30 this type from seamless tubes is usually performed by
rolling, whereby the rolls serving as the forming tools
have a circumference which is equivalent to the length of
the finished conical body following deformation of the
seamless tube. Aside from the fact that the necessary use
35 of seamless starting material substantially increases the
cost of the product, there is a disadvantage in the case
of this known process and the machine necessary to carry
it out in that the forming rolls employed in each case are
only suitable for a certain length of a finished conical
40 body. Consequently, for each required length of the fi-
nished conical body, a different set of rolls has to be
used, and this not only means considerable expenditure in
4 0 ?7
terms of cost but also constitutes a time-consuming method
of operation as changing the forming rolls takes up a con-
siderable amount of time.
5 Forging is another known method for the manufacture of co-
nical bodies from metal tubes with a circular cross sec-
tion. This method of manufacture, however, requires re-
latively high impact forces and comparatively complicated
machines which are correspondingly expensive.
The problem upon which the invention is based lies in imp-
roving a process such as that mentioned in the introduc-
tion so that it can serve for the forming of starting ma-
terial which need no longer be exclusively restricted to
lS seamless tubes, and, in addition, in facilitating the use
of one and the same tool to produce conical or tapered
bodies of various lengths and various degrees of taper
with uniform cross-sectional shapes, irrespective of whe-
ther bodies of circular or polygonal cross section are to
20 be manufactured.
This problem is solved by the invention concerning a
process of the type defined at the beginning in that the
blank, during rotation of the rolls, is drawn by means of
25 a grip tong through the working cross section which forms
a die, and in that the blank is rotated by the grip tong.
Obviously, in the case of the process according to the
invention, the operation of drawing the tube through a die
is combined with a simultaneous rolling operation, with
30 the blank also being rotated around its longitudinal axis.
This results in a particularly uniform product.
In a preferred embodiment of the invention, the angle of
'aper produced can be controlled by modifying the drawing
35 speed of the grip tong and/or modifying the rotary speed
of the rolls. In this way one and the same pair of rolls
can be employed to produce a wide range of different pro-
ducts, while simultaneous rotation of the blank during
drawing also ensures that as round and as uniform a pro-
40 duct as possible is produced irrespective of whether thestarting material was a seamless tube or a tube with a
joint seam.
75 f
Because deformation of the blank normally can only be car-
ried out in one continuous operation, while at the same
time achieving an optimal finished product, in the case of
5 relatively small angles of taper and medium lengths,
working is preferentially performed in several forming
stages, whereby the blank is rotated between the indivi-
dual forming stages by means of the grip tong. The rolls
are also rotated in several discrete steps in accordance
10 with the various stages of the forming operation, whereby
the smallest diameter between the grooves is not reached
until the last stage.
A further, particularly significant feature of the process
15 according to the invention consists in the fact that the
starting material may take the form of blanks with either
a circular or a polygonal cross section.
In the case of a machine for performing the above-des-
20 cribed process, with a pair of rotationally driven rolls,
each of which features on the surface which engages the
blank a groove corresponding in cross section to half the
cross-sectional shape of the blank, said groove being ta-
pered in the circumferential direction of the rolls, and
25 with a grip tong for holding the blank, the problem upon
which the invention is based is essentially solved by the
fact that grip tong is mounted on a rotary shaft aligned
to the longitudinal axis of the blank, a rotary drive is
provided for the grip tong, a device is provided in order
30 to generate a relative motion between the rolls and the
blank, and the speed of the drive of the device and/or the
rolls is variable.
In a preferred embodiment in accordance with the inven-
35 tion, the device for generating the relative motion
consists of a slide which traverses in the longitudinal
direction of the blank, on which slide the grip tong is
mounted.
40 In a modified embodiment in accordance with the invention,
the device for generating the relative motion consists of
2~ 5',
a carriage which traverses in the longitudinal direction
of the blank, on which carriage the rolls are mounted.
In particular it is preferred that a positive drawing
5 drive be provided for the slide, as this is ideally suited
to performing the operation of drawing the tube through
the rolls which together form a die. This may, in the
case of a preferred embodiment, in particular be a chain
drive, although rack-and-pinion drive is also possible
10 as an alternative.
In particular, the invention may be further developed in
that the drive for the rolls is provided by a variable-
speed motor with a gear unit.
In particular, it is advantageous that the rotary drive
for the grip tong be mounted together with the latter on
the slide. It is likewise advantageous to arrange the
drive for the rollers on the carriage.
In order to achieve maximum controllability of the rela-
tive motions between the blank and the rolls, it is fur-
ther advantageous if the drawing drive for the slide or
the carriage is infinitely variable.
In a preferred embodiment of the invention, the grooves
exhibit a semi-circular cross section. It is advantageous
in this connection if the grip tong can be steplessly ro-
tated.
For the processing of blanks with a polygonal cross sec-
tion, the grooves in a modified embodiment are provided
with a polygonal cross section. It is advantageous in
this connection if the grip tong rotation is performed in
35 discrete increments which are defined in accordance with
the angular relationships of the polygonal cross section
of the grooves.
The invention is explained in greater detail in the fol-
40 lowing using the example embodiments indicated in the
drawings, wherein
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Figure 1 shows a very simplified schematic side
. ,
elevation of a first embodiment of the
invention,
Figure 2 shows a side elevation corresponding to Figure
1 of a second embodiment of the invention, and
Figure 3 shows a partially cut-away view of the forming
rolls with their drive.
As shown in the drawings, the machine according to the
invention and generally designated as 1 exhibits as its
main components a pair of rolls 2, 3 (cf. Fig. 3), of
which the working surface 4, which engages with the blank
15 (not shown in the illustration), exhibits in each case a
groove 5 of semi-circular cross section running around
the circumference of the rolls 2, 3. As is particularly
shown in the partially cut-away view of Figure 3, the
groove is tapered in the circumferential direction of the
20 rolls 2, 3 so that when the rolls 2, 3 rotate against
each other, the result is a conically changing cross
section.
In the case of the embodiment of the machine according to
25 the invention shown in Figure 1, provided in a machine
frame 20 is a grip tong 6 which holds the non-illustrated
blank.
The grip tong 6 is mounted on a rotating shaft 7 which is
30 in alignment with the longitudinal axis of the blank, and
a rotary drive is provided for the grip tong as symbolised
by the arrow 8 in Figure 1.
When forming of the tubes into conical bodies, the tube
35 employed as the blank is drawn, during rotation of the
rolls 2, 3, through the deformation cross section formed
between them which operates in a manner similar to that
of a die.
40 For the purpose of this drawing operation, provision has
been made in the embodiment according to Figure 1 for a
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device generally designated 9, by means of which a rela-
tive motion can be generated between the rolls 2, 3 and
the blank.
5 In the ill-~strated embodiment, the device 9 takes the
form of a carriage 12 on which are mounted the rolls 2, 3
with their shafts 21, 22. Also mounted on the carriage
12 is the drive, designated 10, for the rolls.
lQ The drive 10 is preferably a variable-speed motor 14 with
a gear unit 15, which permits infinite variability of the
rotary speed of the rolls.
The carriage 12 is moved in relation to the grip tong 6
15 by a drawing drive 13 which preferably takes the form of
a positive dr ve arrangement such as a chain drive or a
rack-and-pinion drive.
In the case of the embodiment shown in Figure 2, in which
20 the same reference numbers have been employed for the
same components or components performing the same func-
tion, the pair of rolls 2, 3 with their drive 10 are,
in contrast to the embodiment shown in Figure 1, fixed on
a stationary pedestal 16 which forms a part of the
25 machine frame 20, while the grip tong 6 with its rotary
drive 8 is mounted on a slide 11 which moves on guideways
19 when operated by the drawing drive 13.
Figure 3 additionally shows a pair of spur gears 23, 24,
30 by means of which the rolls 2, 3 are rotated in opposite
directions to each other.
In order to form a metal tube into a conical body employ-
ing the machine according to the invention, the metal tube
35 is inserted through the largest cross section between the
opposing rolls 2, 3, and secured in the grip tong. Rota-
tion of the rolls 2, 3 accompanied by simultaneous drawing
causes the tube to be formed into a conical body, whereby
in the case of multi-stage forming, the grip tong is ro-
40 tated between the individual forming stages in order toobtain as round and as uniform a drawn product as pos-
sible.
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In order to be able to produce a product of high quality,
preference is given in the case of large taper angles and
long workpieces, to performing the forming process in se-
5 veral stages, whereby during each forming stage the rollsare only rotated by a fraction of their total circum-
ference. Between the individual forming stages, the grip
tong and thus the partially formed blank is rotated in
order to achieve as uniform a cross-sectional shape as
10 possible over the full length of the finished product.
Thus, the aperture formed by the grooves 5 does not reach
its smallest diameter until the last forming stage.
The drawing operation during rotation of the rolls 2, 3
15 is performed either in accordance with the embodiment
shown in Figure 1, by the carriage carrying the rolls 2, 3
being traversed through operation of the drawing drive 13
away from the rotary but stationary grip tong 6, or in
accordance with the embodiment shown in Figure 2 by the
20 rotationally driven grip tong 6 on its slide 11 being
traversed away from the stationary rolls 2, 3 through
operation of the drawing drive 13.
In both cases, the variable traversing speed of the slide
25 11 or the carriage 12 and/or the variable rotary speed of
the rolls 2, 3 enables the angle of taper of the finished
product to be regulated as required. The rotary motion
of the rolls, which combined with the drawing speed deter-
mines the angle of taper, is altered by means of a speed
30 control system, preferably electronic, which governs the
motor 14.
In any case, a large number of different conical bodies
with differing angles of taper can be produced without
35 changing the tools, i.e. the rolls 2, 3. Moreover, by
virtue of the rotary motion generated by the grip tong, a
product of outstanding uniformity is produced without the
need to use seamless tubes as the starting material.
40 Obviously, blanks of any cross section can be processed
through the appropriate design of the grooves S in the
rolls 2, 3. In the case of round blanks, the grooves are
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of semi-circular cross section as in the described embodi-
ment. In this case, the grip tong is steplessly or con-
tinuously rotatable as there are no angle restrictions.
When processing blanks of polygonal cross section, the
5 grooves exhibit a cross section corresponding to half the
polygon of the cross section of the blanks. In this case,
the grip tong 6 can be rotated in discrete increments
which correspond to the angular relationships prevailing
in the blank.
All the features and advantages of the invention arising
from the description, the claims and the drawings, in-
cluding design details and spatial arrangements, can be
regarded as essential to the invention both individually
15 and in any combination.
