The present invention relates to an apparatus for transversally sawing tubular bodies, for example tubular cores for supporting coils of wound material.
Apparatuses are known for transversally sawing tubular bodies made of such materials as pressed cardboard or plastics, which are well suited for serving as cores for supporting coils of tape material, for example. These apparatuses are normally equipped with a transverse chip-forming saw device, in particular they are equipped with circular rotating blades.
In order to obtain a maximum sawing precision, as well as smoother and more regular end portions of the sawn tubular bodies, a device is normally provided for bringing into rotation the tubular bodies about their own axis while performing a sawing operation by the blade.
Examples of such apparatuses can be found, for instance, in IT1314837 and in WO2008/114115.
These apparatuses comprise a cradle or a roll conveyor consisting of parallel idle rollers on which each tubular body or tube is laid. A peripheral friction drive roller is provided for rotating the tube about its own axis, whereas a pusher means is provided for longitudinally shifting the tube.
This way, in order to obtain a tube portion of a predetermined length, the tube is caused to shift longitudinally by a pusher beyond the blade for such length. Then, the pusher stops and the tube is sawn while it rotates about its own axis.
However, in these conditions, the tube is free to move longitudinally during the sawing operation or even immediately before the sawing operation. One cause for this longitudinal movement may be an imperfect alignment of the longitudinal rollers. In fact, the tube remains in the prefixed working position only if the axes of the apparatus, in particular the axes of the cradle idle rollers and of the drive roller are accurately aligned, and only if the rollers are manufactured with high dimensional precision.
Even small longitudinal displacements from the working position may deteriorate the sawing precision, in particular the precision of the length of the sawn-away tubular portion that are obtained. With the manufacturing and mounting tolerances that can be normally obtained, the improved machines of the type described in the above documents allow to attain a sawn-away portion length precision of about one-tenth of a millimetre. This is a typical desired value for pressed cardboard tubular bodies.
However, a better precision is required for some well-know applications of cardboard tubes, where the length tolerances must be lower than one-tenth of a millimetre. This condition is extremely difficult or substantially impossible to achieve by optimizing the construction of the existing equipment.
Furthermore, a chip-forming sawing operation requires removing sawdust and saw chips from the inside of the tubular bodies, in particular once the sawing operation is over. This is normally carried out by a suction means, therefore a suction passageway should be arranged between the outside and the inside of the tube.
It is therefore an object of the present invention to provide an apparatus for transversally sawing a tubular body with formation of chips, for example for transversally sawing a tube to obtain a core element to support a wound material, in which the tubular body, before and during the sawing step, cannot substantially move in a longitudinal direction with respect to a prefixed working position, in order to obtain a sawing precision higher than what is possible by using a prior art apparatus.
It is a particular object of the invention to provide such an apparatus that allows length tolerances of the sawn tubular bodies better than one-tenth of a millimetre, in particular in the case of tubular bodies made of pressed cardboard.
It is also an object of the invention to provide such an apparatus that enables suction of sawdust and saw chips from the inside of the tubular body during the sawing.
It is also an object of the present invention to provide such an apparatus that does not require changing components or does not require particular adjustments and calibrations in case of change of the diameter of the tubular bodies to be processed.
It is also an object of the present invention to provide such an apparatus that does not occupy important radial spaces outside of the tubular body that is processed.
These and other objects are achieved by an apparatus for transversally sawing a tubular body into tubular portions, in particular for transversally sawing a tubular core for coils of wound material, comprising:
a carriage means for moving the tubular body to a sawing station, the carriage means arranged to engage with a first end of the tubular body and to longitudinally move the tubular body so that a second end of the tubular body is brought beyond the sawing station for a predetermined distance, said distance corresponding to a predetermined sawing length of a tube portion;
a support means that is arranged to receive the tubular body and to provide a support to it at the sawing station, and to allow a rotation of the tubular body about its own longitudinal axis;
a rotation means for bringing into rotation and maintaining in rotation the tubular body about its own longitudinal axis when said tubular body is located at the sawing station;
a saw means for sawing the tubular body in the sawing station, in order to obtain a sawn-away portion of the tubular body of the same length as said distance,
wherein the main feature of the apparatus is that the carriage means comprises a holding means for longitudinally holding the tubular body along the support means, the holding means comprising a rotatable element arranged to relatively rollingly engage with a surface portion of the tubular body.
This prevents the tubular body from moving longitudinally. This way, it is possible to predetermine the length of the sawn-away tubular portions more precisely than what is possible by the prior art equipment. Moreover, this dimensional precision can be obtained even if the construction tolerances of the parts of the apparatus, and/or the mounting tolerances, are stricter than the tolerances commonly used in the manufacture of conventional equipment. For instance, it is possible to obtain sawn-away tubular portions of a predetermined length, for example pressed cardboard tubular portions, with better tolerances than one-tenth of a millimetre.
The longitudinal holding device of the tubular body acts only on a boundary portion of the tube cross section, therefore it does not substantially affect the diameter of the tube. For this reason, it offers advantages over a self-centring mandrel. In fact, at each operation, the self-centring mandrels require determining the position of the centre, and must be adapted to the diameter of the tube, in order to ensure a suitable centring. In some instances, the mandrel must even be replaced with another one of a size suitable for the diameter of the tube to be sawn.
Therefore, by the holding means according to the invention, it is possible to process tubes of various diameters without either replacing mechanical parts or adjusting or calibrating the apparatus.
Furthermore, the holding means according to the invention does not occupy space outside of the tubular body, therefore it does not create any interference with other parts of the apparatus, for instance with the rollers of a support cradle. Moreover, no special construction is required to avoid these interferences, as it would be the case with a self-centring mandrel.
In an exemplary embodiment, the rotatable element is arranged to engage by rolling and pressing onto an inner surface portion of the tubular body proximate to the first end, in particular the rotatable element is arranged to engage by rolling and pressing onto an inner surface portion of the tubular body proximate to the first end and radially corresponding to a surface portion of the tubular body that is in contact with a counter-support element.
Advantageously, the carriage means is configured to translate parallel to the support means between a first position, at a maximum distance from the sawing station, and a second position, at a minimum distance from the sawing station, wherein a loading means is provided for loading a tubular body to be sawn at a loading position set between the first and the second position.
Preferably, the saw means comprises a chip-forming sawing device, for example a blade or a toothed saw. In particular, the saw device may comprise a circular saw that is rotatably arranged about an axis that can be arranged parallel to the longitudinal direction.
Advantageously, the apparatus comprises, especially in this case, a suction means for removing chips that are produced by the saw means. The suction means is arranged within the carriage means, in order to suck, at the first end, chips that are produced at the second end, through the tubular body, in particular the carriage means comprising a plate configured to be arranged adjacent to the first end. The suction means may comprise a flow aperture in the plate, the flow aperture configured to provide an air suction mouth towards the first end.
In particular, the suction means comprises a fixed suction station that is connected to a movable tube extending as a rolling chain from the carriage means, in order to accumulate the sucked chips in the fixed suction station.
The holding device, which comprises a rotatable element, makes it possible to stop the longitudinal slide movement of the tube along the support means and at the same time allows to leave a flow aperture open at the second end of the tubular body, of a size large enough to allow the passage of a duct for sucking the saw chips from the inside of the tube, which form in significant amounts if a saw means is used of the above mentioned type. A different holding system, such as an expansion mandrel, even though it does not create any encumbrance outside of the tubular body, would occupy substantially the whole end section, and would therefore not allow any free passage for sawdust and saw chips suction.
In particular, the toothed circular blade is mounted on a carriage that is transversally slidable with respect to the longitudinal direction. Advantageously, an actuation means is provided for moving the carriage according to a faster approach stroke and a slower sawing stroke.
In particular, the rotatable element is a roller configured to rotatably and frictionally engage with the inner surface.
In an exemplary embodiment, the rotatable element has a profile configured to emboss the material of the inner surface of the tubular body, to make a rolling track for the rotatable element that provides a precise longitudinal reference, in particular the roller has an incision means that is configured to make a circular notch in the inner surface. In particular, the incision means comprises a cutting edge that circumferentially extends along the rotatable element. For instance, the cutting edge has a triangular or trapezoidal cross section.
In particular, the support means comprises a cradle comprising two elongated rollers that are longitudinally and rotatably arranged parallel to each other, in order to receive the tubular element laying by gravity and parallel onto the rollers.
Preferably, and in particular in this case, the inner surface portion of the tubular body, with which the rotatable element is configured to engage, is a lowermost portion, and a passageway is provided for the carriage means between the two rollers.
Advantageously, an adjustment means is provided for adjusting the radial position of the rotatable element with respect to the tubular body, said adjustment means configured to cause the rotatable element to rollingly engage with an inner surface portion of the tubular body by pressing on it, said portion having a predetermined thickness. In particular, the radial position adjustment means comprises a retaining means for retaining the rotatable element at a central position and a recall means for recalling the rotatable element towards a peripheral position of the rotatable element, the recall means adapted to intervene recalling the rotatable element into contact with the inner surface portion of the tubular body. This way, the machine is easily adaptable to the thickness of the tubular body. The tape-retaining means may be a pneumatic means, while the recall means may be a resilient means or of a magnetic means.
Moreover, a scrap expulsion station may be provided at a first movement position of the carriage means at a remote position with respect to the sawing station, in particular the scrap expulsion station comprises a pusher configured to push the scraps transversally with respect to a conveying direction of the carriage means.
Advantageously, the sawing station comprises a position sensor, for example an optical position sensor, which is arranged to detect the position of the carriage means and/or of the tubular body being processed.
Advantageously, in the sawing station a means is provided for reversing the rotation speed of the tubular body during the sawing once the tubular body has rotated by a predetermined angle. This way, it is possible to obtain a very high sawing precision. In particular, this predetermined angle exceeds 360°, in particular is set between 380° and 390°.
In an exemplary embodiment, a tubular body feeding means is provided comprising an elongated member that has a star-shaped cross section and comprises at least three continuous radial protrusions. The elongated member is adapted to rotate about an own longitudinal axis parallel to the longitudinal axis. The continuous protrusions may extend along the whole length of the star-shaped member. In particular, the star-shaped member may have four protrusions, that are sequentially arranged at a right angle with respect to each other.
The rollers of the cradle are mounted at a height lower than the longitudinal axis of the star-shaped member, such that a tubular body is released on the cradle after a predetermined rotation of the star-shaped body has occurred.
The invention will be now shown with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings, in which:
With reference to
Apparatus 100 comprises a frame 9 on which a support 12 is arranged for a sawing station 30. In particular, sawing station 30 comprises a chip-forming sawing device. For example, sawing station 30 comprises a circular saw or blade 35 that is rotatably arranged about an own axis 46, for carrying out a transverse sawing operation of tubular body 1 with formation of chips. In particular, sawing station 30 may be equipped and may work as described in IT1314837 or in WO2008/114115.
Below sawing station 30, a means 19′ may be provided for collecting sawn-away portions 1′ obtained by transversally sawing tubular body 1.
Apparatus 100 has a load means for loading tubular bodies to be sawn, for instance a conventional load means 26, as described more in detail hereinafter, with reference to
Transverse sawing apparatus 100 also comprises a support 10 that is configured to receive a tubular body 1 from the load means. The support is made in such a way to allow a rotation of tubular body 1 about its own longitudinal axis 16 during the transverse sawing, in order to assist this step. For example, as shown in
In
In
As shown in
Once tubular body 1 has been arranged in the saw position of
By the expression “transverse sawing” a sawing step is meant that comprises cutting tubular body 1 at all its generatrices, but not necessarily according to a cut plane perpendicular to longitudinal axis 16 of tubular body 1, as diagrammatically shown in the drawings. In other words, saw means 35 may be arranged to execute a cut according to at least one cut plane at an angle with respect to longitudinal axis 16 of tubular body 1, in particular circular saw 35 may be arranged according to a plane at an angle with respect to axis 16, by actuating a conventional angular positioning means, not shown, of circular saw 35.
According to the invention, as
In particular, the cross sectional view of
Rotatable element 71 protrudes from a front plate 53 of slide element 50 through a hole 54. In slide element 50 a means is arranged for vertically displacing rotatable element 71 between a raised position (
In the exemplary embodiment, as depicted, longitudinal holding means 14 advantageously also comprises a countersupport member 72, that is arranged to vertically slide between a lowered position (
In
In
From the sawing of tubular body 1, which is shown in
Still with reference to
As shown in
In alternative, according to the diagrammatical view of
In
More in detail, last tubular portion 3 is brought by slide element 50 to a connection station of connection station 60 and is disengaged from the longitudinal holding means 71,72. Subsequently, slide element 50 is brought to the station of
Therefore, connection station 60 allows reducing the scraps. If desired, connection station 60 may be excluded from the operation schedule, in which case last tubular portion 3 is treated as a scrap or a waste material, as described with reference to
Frame 9 has feet 9′ for fixing or laying the support on a ground or on a base frame. Independently from what described with reference to connection station 60, apparatus 102 may comprise a loading station 65 for loading tubular elements 1 to be sawn and/or to be connected on the support means, in the case shown on the cradle comprising a couple of parallel rotatable rollers 11′,11″. The loading station may comprise a driven star-shaped feeder 26, for example of the type described in detail in WO2008/114115.
Independently from the above description of connection station 60 and of loading station 65, apparatus 102 may comprise a scrap expulsion station 80 at a remote position with respect to sawing station 30, for example opposite to sawing station 30 with respect to loading station 65, i.e. at the position of slide element 50 that is at a maximum distance from saw means 35, i.e. at the position that is diagrammatically shown in
Independently from positions 60, 85, 80, apparatus 102 is provided with the flexible tube, i.e. with a movable suction tube 24 extending as a rolling chain, which belongs to the chip suction means of
Carriage means 50 comprises a lower portion 52 and an upper portion 51 that slides on lower portion 55, according to a solution that is advantageous for treating large and small diameter tubes, as described hereinafter.
The foregoing description of specific exemplary embodiments will so fully reveal the invention according to the conceptual point of view, such that others, by applying current knowledge, will be able to modify and/or adapt in various applications this specific exemplary embodiments without further research and without parting from the invention, and, then it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation.
Number | Date | Country | Kind |
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PI2011A000084 | Jul 2011 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB2012/053748 | 7/23/2012 | WO | 00 | 1/23/2014 |