EP0225235B1 - Tube-cutting apparatus - Google Patents

Description

The invention relates to a device for cutting tubes comprising at least one knife which cooperates at the end of cutting with a counterpart known as a counter knife disposed inside the tube to be cut (see for example EP-A 0 125 175).

It is known to cut tubes by means of knives which penetrate the thickness of the tube while the latter is rotated.

To cut certain tubes and more particularly tubes made of non-rigid material, such as cardboard tubes, it is necessary to place inside the tube a counterpart on which the knife comes to finish cutting.

Up to now, the counterpart has been mechanically connected by means arranged inside the tube in order to ensure that it is held in a fixed position or to allow it to be displaced longitudinally.

Chainsaws intended to cut individual tubes into several sections are in fact provided with knives and a counterpart fixed longitudinally, the latter being arranged on a fixed mandrel on which the tube is threaded.

On the contrary, in the cutting devices of a continuously manufactured tube, such as a spiraling machine for cardboard tube for example, it is necessary that the knife (s) and the counterpart follow longitudinally and synchronously the tube during manufacture , at the time of cutting, the knives and the counterpart being returned to the initial position after each cutting by a means passing through the rolling mandrel of the sprialeuse.

It is clear that the mechanical connection of the counterpart is a handicap and in particular prevents certain applications.

For a chainsaw of unitary tubes for example, the supply of tubes is hitherto necessarily done on the same side as the discharge of the sections since one side is prohibited by the connection of the counterpart, which prevents a continuous supply.

In the cutting devices of a continuously manufactured tube, it is not always possible to drill or use the inside of the rolling mandrel when, for example, the diameters are too small or when the inside of the mandrel is already used for other functions (heating mandrel, cooling, ...) or even when said mandrel must be full to better resist certain constraints.

This is why the inventor sought and found a means which makes it possible to maintain in position and / or to move the counterpart hereinafter referred to as a counter knife, without the latter being mechanically connected to an external means.

The cutting device according to the invention is remarkable in that the counter knife is mechanically connected to a core of high magnetic susceptibility while a magnetic induction means comprising a coil is arranged to create a magnetic field through the tube to be cut, with induction lines which are substantially longitudinal in the core, so as to be able to act magnetically on the longitudinal position of said core and thereby on that of the counter knife as a function of the longitudinal position of the knife.

Advantageously, the winding of the magnetic induction means is wound in a carcass around the tube to be cut.

According to an embodiment provided with at least one knife with a fixed longitudinal position for cutting off individual tubes, the magnetic induction means has a fixed longitudinal position and creates induction lines of constant shapes and longitudinal positions, while that the core and the counter knife are connected together by a rigid non-magnetic element which is fixed integrally longitudinally to the core and the counter knife.

Advantageously in this case, the fixing of the rigid element to the counter knife and / or to the core is free. rotation, so as to allow freedom of rotation of the counter knife relative to the core.

Preferably, the knife or knives are positioned on one side of the magnetic induction means and a pusher is provided, preferably on the side of said knives, to supply the device individually with cut-off tubes and to advance each tube lengthwise. desired as a function of the sections to be obtained, while the cut sections are evacuated on the side opposite the pusher relative to the induction means.

It is clear that with such a device, there is, compared to the prior art, an inlet side and an outlet side, which allows a continuous supply and which in particular facilitates counting, sorting losses, storing sections, ...

However, the invention also relates to a device for cutting a tube manufactured continuously, the knife or knives being moved longitudinally at the time of cutting, synchronously with the advancement of the tube during manufacture, such as, for example , in the known device which is described in patent EP-A 0 125 175 in the name of the same applicant.

For this application, the invention recommends that the magnetic induction means be arranged so as to create a variable magnetic field in position, the movement of the field and consequently that of the core being slaved to the cutting-off cycle.

To do this, the induction means is for example mounted on a carriage movable longitudinally and whose movement is controlled by the cutting cycle.

However, when the tube to be cut has a large diameter and / or thickness, the size, and consequently the weight of the induction means, also become important so that the setting in motion of said induction means is difficult.

This is why the invention proposes in this case a remarkable embodiment in that the induction means has a fixed longitudinal position and in that a tubular element made of material with high magnetic susceptibility is mounted movable longitudinally around the tube. to be cut, said tubular element having a part with low magnetic susceptibility, preferably of length at most equal to that of the core, while the movement of the tubular element is slaved to the cutting cycle so that the displacement of said tubular element in the magnetic field of the induction means causes the displacement of the core which channels the lines induction through the part with high magnetic susceptibility of the tubular element.

In the case of a carriage or of a movable tubular element, the core and the counter knife can be connected together by a rigid non-magnetic element which is fixed integrally longitudinally to the core and the counter knife, while the carriage, or respectively the tubular element, is slaved to the movement of the tube, so that the core and therefore the counter knife follow synchronously the movement of the tube and the knife during at least the action of the latter, a servo being provided to return the carriage, or respectively the tubular element, and therefore the counter knife, in the initial position after each cutting for a new cutting cycle.

However, it is also possible that the core and the counter knife are connected in such a way that the counter knife can deviate freely from a certain length of the core while the carriage, or respectively the tubular element, is controlled. during the cutting cycle in such a way that the core advances rapidly by a certain length before the action of the knives, approaching the counter knife, the outside diameter of which is preferably substantially equal to the inside diameter of the tube so that said counter -cuteau can be driven freely by the tube itself by moving away from the core during cutting, a servo being provided to bring the carriage, or respectively the tubular element and therefore the counter knife, in the initial position after each cutting for a new cutting cycle.

In the latter case, the core and the counter knife are for example interconnected by a cable so that the advancement of the core creates a slack in said cable allowing freedom of advancement of the counter knife and that backward movement of the core creates a tension in the cable enabling the said counter-knife to be brought back.

Alternatively, the cable is replaced by a rigid connecting rod which slides freely in the core so that the advancement of the core is effected by sliding without acting on the counter knife while a stop is provided upstream. of the core so that a return to the back of the core brings the counter knife back by pulling the connecting rod via said stop.

• - la figure 1 est une élévation représentant schématiquement un mode de réalisation pour tronçonneuse de tubes unitaires,
• - la figure 2 est une vue partielle de dessus de la figure 1,
• - la figure 3 est une vue en bout (côté bobinage) de la figure 1,
• - .Ia figure 4 montre schématiquement en élévation un premier mode de réalisation, pour tronçonnage d'un tube carton fabriqué en continu,
• - la figure 5 montre schématiquement en élévation un second mode de réalisation, pour tronçonnage d'un tube carton fabriqué en continu.

The invention will be clearly understood and other particularities will appear on reading the description which follows and which refers to the appended drawings in which:

• FIG. 1 is an elevation schematically showing an embodiment for a chainsaw for unit tubes,
• FIG. 2 is a partial top view of FIG. 1,
• FIG. 3 is an end view (winding side) of FIG. 1,
• FIG. 4 schematically shows in elevation a first embodiment, for cutting a continuously manufactured cardboard tube,
• - Figure 5 shows schematically in elevation a second embodiment, for cutting a continuously manufactured cardboard tube.

Figures 1 to 3 show a frame 1 which supports, in a fixed manner, a carcass 2 containing a coil 3 of copper wire, arranged so as to surround the tube 4 to be cut.

The tube 4 is shown here cut longitudinally (as well as the carcass 2) to reveal the interior.

The tube 4 can be driven in rotation by means of drive rollers 5a, 5b (FIGS. 1 and 2) themselves actuated by a motor 6 and through a set of gears 7 (FIG. 1).

The tube 4 is further maintained and centered by rollers 8a to 8d arranged on the carcass 2 (8a and 8d are visible in FIGS. 1 and 2, 8a to 8c are visible in FIG. 3 while two other corresponding non-visible rollers the rollers 8b and 8c are provided on the other side of the carcass 2).

The shape of the rollers, as shown in the drawings, is provided to allow both a longitudinal displacement and a rotation of the tube 4.

In the tube 4, is arranged a core 9 of good magnetic susceptibility such as soft iron mechanically connected to a counter knife 10 by means of a connecting piece 11 made of non-magnetic material (for example aluminum). The mechanical connections between the core 9 and the part 11 and between the latter and the counter knife 10 are such that they ensure, on the one hand, a free rotation of these three elements with respect to each other (by means of parts rolling) but, on the other hand, longitudinal solidarity so that the counter knife 10 can be actuated in rotation with the tube 4 without driving the core 9.

Above the tube 4, on the side opposite to the rollers 5a, 5b is arranged in a fixed manner longitudinally, a knife 12 (Figures 1 and 2) in the form of a disc.

As shown more particularly in the detail in FIG. 1, the knife 12 is pivotally mounted so that it can penetrate the thickness of the tube 4.

On the side opposite to the carcass 2, there is further provided a pusher 13, mounted free to rotate, at the end of an actuating rod 14, guided in the chassis 1.

In the embodiment described with reference to Figures 1 to 3, each tube is supplied by the pusher 13, while the rod 14 is actuated in the direction of the arrow F ₁ (Figure 1) so as to properly position said tube by versus knife 12.

It is thus possible to make one or more sections by actuating the knife 12 after rotation of the tube. Each section is then evacuated by the pusher 13 on the side opposite the latter relative to the carcass 2.

The iron core 9 is held in position by to the magnetic field created by the winding 3 traversed by an electric current so that the counter knife 10 remains in good position relative to the knife 12.

It is clear, of course, that it is possible to have several knives 12, so as to make rings for example.

Likewise, the knife (s) and the counter knife could be arranged on the other side of the carcass 2.

This device is particularly interesting since, on one side of the carcass, the tubes are supplied, while on the other side, the sections obtained are recovered.

FIGS. 4 and 5 show two embodiments more particularly intended for cutting-off devices provided at the end of spiraling machines for the continuous production of cardboard tubes and more generally, for machines in which the tube in production or in one piece is moved. longitudinally at the time of cutting.

In this case, the knife or knives are also moved longitudinally to follow the cutting tube during cutting. It is therefore necessary then, that the counter knife follows the movement of the tube.

To this end, the embodiment of Figure 4 has, as in Figure 1, a carcass 2, provided with a coil 3, while a soft iron core 9 'is mechanically connected to a counter knife 10 'by means here of a non-magnetic rod 11' possibly free to rotate on the core 9 'and / or on the counter knife 10'.

This device also includes knives 12 ′ (here two are shown), possibly a schematic entry at 15, for rotating the drive rollers, such as 5 ′ a with, in addition here, pressure rollers 16.

In this device, the knives 12 ′ are driven synchronously with the advancement of the tube 4 in the direction of the arrow F ₂ .

To allow the counter knife 10 'to also follow the tube 4, the carcass 2 is fixed here on a mobile carriage 17 which is guided on slides 18 of a fixed frame.

The carriage 17 is driven by a crank rod system 19, synchronously with the advancement of the tube 4 (by a servo-control not shown).

It is perfectly clear that the rod 11 'makes it possible to subject the core 9' and the counter knife 10 'longitudinally so that the latter can follow the tube 4 and the knives 12' in their movement of longitudinal translation since the carriage 17 transports the winding 3 whose magnetic field forces the core 9 'to follow the movement of said winding.

Means are obviously provided for bringing the carriage 17 and the knives 12 'back to the initial position for a new cutting cycle, said carriage having a reciprocating movement according to the double arrow Fs in FIG. 4.

In the embodiment which has just been described, the tube is actuated in rotation during its manufacture by spiraling so that the means 15 and 5'a are not compulsory.

Figure 5 shows another particularly interesting and original embodiment since it allows. to have a fixed means of induction (carcass-winding) while allowing movement of the core.

Here we find the carcass 2, the winding 3, the tube 4, a cutting plate with one or more knives schematized in 12 ", a soft iron core 9" and a counter knife 10 "connected here to said core by a rod 11 ".

The core 9 ", however, here has a longitudinal dimension smaller than that of the previous embodiments, while the rod 11" passes through the core 9 "and has a stop 20 at its free end.

In this embodiment, a tube 21 made of material of good magnetic susceptibility (soft iron, steel, etc.) is mounted coaxially around the tube 4 to be cut.

The tube 21 has in its central part, a ring 22 made of a material of very low magnetic susceptibility (in copper for example) while the said tube is mounted on a carriage 23 mounted longitudinally movable and actuated for example by a jack 24 so as to follow the movement of the tube 4 according to arrow F ₄ . The carriage 23 will also have a back and forth movement according to the double arrow F _s as described below.

Compared to FIG. 4, it can be seen that the carcass 2 and the winding 3 are fixed and that it is therefore possible to use heavy means for tubes of large diameters for example.

When the tube 21 is moved by the carriage 23, the induction lines pass through the magnetic part of said tube and are channeled by the core 9 ", said lines bypassing the ring 22.

In this way, the core 9 "follows the movement of the tube 21.

In the embodiment shown in FIG. 5, the rod 11 '"slides in the core 9" so that the counter knife 10 "is not influenced by the movement of the core 9" in the direction of the arrow F ₄ . On the other hand, it is clear that a return in the other direction will allow the core 9 "to pull on the counter knife 10" thanks to the stop 20 of the rod 11 ".

This provision applies in particular to the device described in the European patent 0 125 175 already cited, in which the counter knife is driven during cutting by the tube itself, then brought back in the opposite direction for a new cycle. In this case, it suffices that the tube 21 undergoes a rapid movement towards the counter knife 10 "as it approaches it, said counter knife 10" continuing its movement by being simply driven by the tube 4 (the diameters being studied accordingly), while a servo is provided to abruptly return the carriage 23 to the initial position after each cutting.

However, the same result would be obtained by replacing the rod 11 "with a simple cable.

It is clear that the connecting piece 11 and the rod 11 'of the embodiments of Figures 1 and 4 respectively, are interchangeable.

Likewise, the rod 11 ′ in FIG. 4 can be replaced by a cable or a sliding rod of the type eg of the rod 11 "in FIG. 5, the carriage 17 having a movement of the type described in connection with the carriage 23 in FIG. 5.

Finally, in the embodiment described in FIG. 5, it is of course possible to have a movement of the tube 21 synchronous with that of the tube 4, the connection between the core 9 "and the counter knife 10" being rigid longitudinally by means of a part of the type of that of FIG. 1 or of a rod of the type of that of FIG. 4.

The invention relates mainly, but not exclusively, to cardboard tubes.

In addition, the tubes may have a circular or polygonal section, in the latter case, the means for rotating provided in FIG. 1 can for example be replaced by a pusher mounted to rotate.

Claims (12)

1. Device for cutting tubes comprising a least one knife (12, 12', 12") which co-operates at the end of cutting with a counter part referred to hereinafter as a counter knife (10, 10_', 10") disposed inside the tube (4) to be cut, characterised in that the counter knife (10, 10', 10") is connected mechanically to a core (9, 9', 9") with high magnetic susceptibility while a magnetic induction means comprising a winding (3) is arranged to create a magnetic field through the tube (4) to be cut with induction lines which are substantially longitudinal in the core (9, 9', 9") so as to be able to act magnetically on the longitudinal position of said core and thence on the position of the counter knife (10, 10', 10") according to the longitudinal position of the knife.

2. Device as in claim 1, characterised in that the winding (3) of the magnetic induction means is wound in a casing (2) around the tube to be cut.

3. Device as in one of claims 1 and 2, provided with at least one knife (12) with a fixed longitudinal position for cutting unit tubes, characterised in that the magnetic induction means has a fixed longitudinal position and creates induction lines with constant forms and longitudinal positions while the core (9) and the counter knife (10) are connected together by a non-magnetic rigid element (11, 11') which is locked longitudinally to the core (9) and to the counter knife (10).

4. Device as in claim 3, characterised in that the fixture of the rigid element (11, 11') to the counter knife (10) and/or to the core (9) is free to rotate so as to permit freedom of rotation of the counter knife relative to the core.

5. Device as in one of claims 3 and 4, characterised in the knife or knives (12) are positioned on one side of the magnetic induction means (2, 3) and in that a pusher (13) is provided, preferably on the side of said knives, to supply the device unitarily with tubes to be cut and to advance each tube by the required length according to the sections to be obtained while the cut sections are discharged on the opposite side to the pusher in relation to the induction means.

6. Device as in one of claims 1 and 2 for cutting a continuously manufactured tube, the knife or knives (12_', 12") being moved longitudinally at the moment of cutting in synchronisation with the advance of the tube being manufactured, characterised in that the magnetic induction means is arranged so as to create a magnetic field of variable position, the movement of the field and consequently that of the core (9', 9") being controlled by the cutting cycle.

7. Device as in claim 6, characterised in that the induction means is mounted on a carrier (17) which can be moved longitudinally and the movement of which is controlled by the cutting cycle.

8. Device as in claim 6, characterised in that the induction means has a fixed longitudinal position and in that a tubular element (21) made of material with high magnetic susceptibility is mounted so that it can move longitudinally around the tube (4) to be cut, said tubular element having a part (22) with low magnetic susceptibility with a length preferably at most equal to that of the core (9"), while the movement of the tubular element (21) is controlled by the cutting cycle so that the movement of said tubular element in the magnetic field of the induction means leads to movement of the core (9") which channels the induction lines passing through the part of the tubular element with high magnetic susceptibility.

9. Device as in one of claims 7 and 8, characterised in that the core (9_', 9_") and the counter knife (10', 10") are connected together by a non-magnetic rigid element (11,11') which is locked longitudinally to the core and to the counter knife, while the carrier (17) or the tubular element (21) respectively is controlled by the movement of the tube so that the core and thus the counter knife synchronously follow the movement of the tube and of the knife at least during the operation of the latter, a control being provided to return the carrier or the tubular element respectively, and thus the counter knife, to the initial position after each cut for a new cutting cycle.

10. Device as in one of claims 7 and 8, characterised in that the core (9', 9") and the counter knife (10', 10") are connected so that the counter knife is free to move away from the core a certain distance while the carrier (17) or the tubular element (21) respectively is controlled by the cutting cycle so that the core advances rapidly a certain distance before the operation of the knives, moving towards the counter knife the outside diameter of which is preferably substantially equal to the inside diameter of the tube so that said counter knife can be entrained freely by the tube itself while moving away from the core during cutting, a control being provided to return the carrier or the tubular element respectively, and thus the counter knife, to the initial position after each cut for a new cutting cycle.

11. Device according to claim 10, characterised in that the core (9', 9") and the counter knife (10', 10") are connected together by a cable so that the advance of the core creates slack in said cable giving the counter knife freedom to advance and in that a return movement of the core creates a tension in the cable so that said counter knife can be returned.

12. Device as in claim 10, characterised in that the core (9', 9") and the counter knife (10', 10") are connected together by a rigid link (11") which slides freely in the core so that the core is advanced by sliding without acting on the counter knife while a stop (20) is provided upstream of the core so that a return movement of the core returns the counter knife by pulling the link (11") through the intermediary of said stop (20).

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