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Description  |
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BACKGROUND OF THE INVENTION
The invention relates to a cutting and grooving device for paper and
cardboard webs, comprising at least two rotatably driven shafts with at
least one tool carrier for a cutting or grooving tool arranged thereon,
said tool carrier comprising at least one radially movable chuck adapted
to be engaged with the shaft, and an actuating device for the chuck
controllable from outside the shaft.
Machines for longitudinally cutting and longitudinally grooving paper or
cardboard webs normally comprise at least one pair of rolls with annularly
shaped cutting or grooving tools, in order to cut or groove the web
passing through in a longitudinal direction. Dependant respectively on the
order to be carried out, the position of the tools on the shafts must be
newly adjusted. For this purpose, the tools are adapted to be clamped onto
the shafts and to be disengaged again in case of necessity. So that an
adjustment of the tools may be performed as quickly as possible, it is
aimed at carrying out the disengagement and clamping of the tools
automatically and without any manual operation. In this connection it is
known to design the shafts as so-called expanding shafts which may be
radially enlarged with the aid of a pressure medium in order to tightly
clamp the tools (German disclosure letter No. 2 250 508). It is also known
to arrange expandable hoses in grooves of the tool shafts, in order to
tightly clamp the tools. The grooves are extending either annularly or
helically. Such a process has proved to be absolutely useful. What is
disadvantageous, however, is the wear.
It has furthermore become known to arrange several chucks in the tool
carrier and bring the chucks into engagement with the shafts with the aid
of one or several pressure hoses (German disclosure letter No. 2 059 970).
What is disadvantageous with the known device is the manner of compressed
air supply as well as the control of the compressed air supply and
discharge thereof when clamping and disengaging the shaft.
It is therefore the object of the invention to improve the cutting and
grooving device mentioned at the beginning in such a manner that the
cutting and/or grooving tools may be tightly clamped on a shaft and
disengaged again in an especially simple manner.
SUMMARY OF THE INVENTION
The above object is attained in accordance with the invention in that the
chuck is adapted to be actuated magnetically via a current supply means.
Preferably, several magnetically actuated chucks are employed which are
arranged radially and equally spaced circumferentially. The chuck may on
its part be designed to be magnetic. Alternatively, the chuck may be
adapted to be actuated by an electromagnet. What is essential to the
invention is that the power of actuation for clamping a tool onto the
shaft is applied electromagnetically. For this purpose, a current supply
is needed to the individual chucks. Said current, however may be easily
transferred to the movable shaft via slip rings. One embodiment of the
invention provides in this connection that two current-collecting rails
are rotating together with a shaft and each tool carrier is movable in an
axial direction relative to the current-collecting rails and is insulated
with respect to the current-collecting rails and is provided with two
spring-biased contact elements which are in contact with the
current-collecting rails. The current-collecting rails are rotating with
the shaft and are extending through openings and recesses, respectively,
of the tool carriers. As a result, the tool carriers may be displaced on
the shaft unobstructedly. The current-collecting rails may also be
countersunk in the shaft. The contact elements such as carbon brushes, for
example, are in permanent contact with the current-collecting rails, in
order to transfer the current from the current-collecting rails to the
individual magnetic arrangements in the chucks. The current-collecting
rails may be connected at one end thereof to a slip ring arrangement. It
goes without saying that the shaft itself may be used as a mass conductor,
so that one current-collecting rail is in conductive contact with the
shaft. Another possibility consists in that a movable contact is
associated with each tool carrier instead of a current-collecting rail,
said contact being in permanent engagement with the shaft and being
connected to the individual magnetic arrangements in the chucks via a
line. In this case, only one current-collecting rail is utilized.
What is especially advantageous is to associate springs with the chucks.
One possibility consists in that the chucks are biased radially away from
the shaft with the aid of said springs, in order to obtain a quick
disengagement of the tool carrier from the shaft when the magnetic
excitation is switched off. According to another embodiment of the
invention the chucks are biased in a direction towards the shaft by means
of a spring arrangement. The springs take care of the clamping of the
tools onto the shaft, while the magnetic acutation is made use of only for
a temporary disengagement of the tools.
Expenditure caused by mechanical means for the tool carriers and the
current supply as well as control means for actuating the
electromagnetically biased chucks is exremely low. Apart from the easily
replaceable carbon brushes in a slip ring type transfer, wear occurring
with the known arrangement is next to zero. The transit time for
disengaging or clamping the tools on the shaft is not greater than with
expanding shafts or similar devices.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in the following in more detail by way of
drawings.
FIG. 1 shows a sectional view of a tool carrier on a tool shaft according
to the invention in an extremely diagrammatic representation.
FIG. 2 shows a sectional view of two tool shafts with cooperating tools on
tool carriers in accordance with another embodiment of the invention.
FIG. 3 shows a sectional view of the arrangement according to FIG. 2 taken
along line 3--3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Referring first to the embodiment of FIG. 1, seated on a shaft 3 of a
longitudinal cutting and grooving device for paper or cardboard webs is an
annular tool carrier 1 for a cutting tool 6, for example. As is well known
with such devices, pairs of shafts are employed. Seated on the second
shaft is a counter tool for a cutting or grooving tool. Both shafts are
rotated by means of a suitable driving device.
Six radial recesses 7 are formed in the tool carrier 1 from the inner
circumference thereof, each having a chuck 2 movably supported therein.
The chucks 2 are suitably shaped to meet the recesses but may be adjusted
radially in a limited extent without causing much expenditure. On the
radially inner surface the chucks are adapted to the contour of the shaft
3. Each chuck 2 is biased by springs 8 urging the chucks into engagement
with the circumference of the shaft 3. Thereby, the tool carrier 1 is
tightly clamped onto the shaft 3. The chucks are furthermore actuable by a
magnetic actuating means not shown, i.e. in such a manner that upon
excitation of the magnetic arrangement the chucks 2 are adjusted radially
away from the shaft 3 against the springs 8. Owing thereto, the tool
carrier 1 may be displaced freely on the shaft 3.
Rotating with the shaft 3 are two current-collecting rails 9, 10, which are
separated from each other by means of an insulation 4. Both rails 9, 10 as
well as an insulation 11 on both sides of the rails 9, 10 are accommodated
in a groove 12 of the tool carrier 1. The rails 9, 10 are, besides,
electrically insulated also with respect to the shaft 3. Brushes 5 are in
contact with the rails while being biased by springs 13. Respectively
connected to the brushes 5 are lines 14 and 15, respectively, which are
leading to the individual magnetic arrangements of the chucks 2. The
current-collecting rails 9, 10 are in engagement with stationary slip
rings (not shown in FIG. 1), so that the current may be transferred onto
the magnetic arrangements in the chucks 2 from the stationary current
source.
It goes without saying that the shaft 3 may be used as a mass conductor. In
that case, one of the two current-collecting rails 9, 10 may be
electrically connected to the shaft 3. Alternatively, each tool carrier 1
may have associated thereto a movable contact instead of one of the two
current-collecting rails 9, 10, said movable contact being in conductive
engagement with the shaft 3. In all the cases, care is taken that the tool
carrier may be adjusted unobstructedly in the direction of the axis of the
shaft 3. In the direction of rotation, on the contrary, the tool carrier 1
is fixed by the current-collecting rails 9, 10.
If, instead of the springs 8, springs are employed which are effective in
an opposite direction, the system shown may likewise be used in an
advantageous manner. In this case the springs are serving the purpose of
overcoming the remanence of magnetism possibly present when disengaging
the tool carrier.
Besides, it is advantageous when the chucks are movable radially by a
certain extent as is represented in the drawing. It is possible in this
manner to balance different transverse stresses on the tool.
In the embodiments according to FIGS. 2 and 3, two tool shafts 20, 21 are
provided having several tool carriers with tools arranged thereon.
However, only one upper tool carrier 22 and one lower tool carrier 23 are
shown in the drawing. They comprise, as shown in FIG. 2, an upper knife 24
and a lower knife 25, respectively, which are cooperating with each other
in a manner known per se. The upper and lower tool carriers 22, 23 each
comprise four equally circumferentially spaced magnetic arrangements 37.
As may be seen from FIG. 3, each magnetic arrangement comprises a sticking
magnet 26, which is slidably supported in a suitable housing of the tool
carrier 22 and 23, respectively, by means of a rubber sleeve 27. Arranged
on the side facing away from the tool shaft is a flat rubber spring 28
urging the sticking magnet 26 against the shaft 21 with a certain
pressure. Current-collecting rails 29 and 30, respectively, are disposed
in a groove of the shafts 20, 21 in insulated arrangement. A further
current-collecting rail 31, 32 is arranged on the shaft 20 and 21,
respectively, adjacent a magnetic arrangement 37. Each tool carrier 22 and
23, respectively, comprises a brush arrangement 33 with brushes
cooperating with the current-collecting rails 29 to 32. The arrangement of
brushes is connected to each magnetic arrangement 37, which is not shown
in FIGS. 2 and 3.
Two slip rings 35, 36 are fastened at the shaft 20 and 21, respectively, in
an insulated manner by means of retaining bolts 34. The slip rings 35, 36
are connected to the current-collecting rails 29 to 32 via conduits (not
shown). Cooperating with the slip rings 34, 35 is an arrangement of
brushes 36, the brushes of which are connected to conductors connected to
a voltage source of 24 volts. It is possible with the aid of the current
supply as shown and described to respectively excite and switch off the
magnetic arrangements 37 in the individual tool carriers 22, 23. Upon
excitation, the sticking magnets 26 will exert a pressure against the
shafts 20 and 21, respectively, in order to fix the tool carriers at the
shaft. Upon positioning the tool carriers, the magnets are de-energized.
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