AUTOMATED MACHINE TO FOLD IN A ZIGZAG MANNER AND STACK A CREASED TAPE MADE OF A SUFFICIENTLY RIGID MATERIAL

Automated machine to fold in a zigzag manner and stack a creased tape made of a sufficiently rigid material and provided with a plurality of transverse creasings equidistant with respect to each other, comprising feed means suitable to feed the creased tape in a determinate direction of feed toward a folding device of the rotary type suitable to fold it in a zigzag manner and to convey it toward collection means. The folding device comprises four parallel pairs of main arms, having the same length and disposed in a cross, which rotate in a direction of rotation consistent with the direction of feed of the creased tape around a central axis of rotation perpendicular to the latter, four corresponding parallel pairs of secondary arms, pivoted to the peripheral ends of the main arms, toward the inside thereof and rotatable in an opposite direction to the latter, and four folding rods pivoted to the peripheral ends of the secondary arms, so that each of the four folding rods is suitable to describe in space a substantially elliptical trajectory. The folding rods are suitable to intercept the creased tape in correspondence to every two of the transverse creasings. The major axis of the trajectory is substantially horizontal and the central stacking axis of the collection means is substantially vertical and parallel to the minor axis of the trajectory.

DESCRIPTION OF ONE FORM OF EMBODIMENT OF THE PRESENT INVENTION

With reference toFIGS. 1 and 2, a machine10according to the present invention is suitable to fold and stack in a zigzag manner a creased tape11(FIGS. 2 and 3) made of a material, for example cardboard, with a thickness of about 3 mm to about 8 mm and therefore sufficiently rigid, that is, so that it does not deform easily.

The creased tape11, by way of example, has a maximum width of about 3,000 mm and is provided with transverse creasings12at intervals to each other by a determinate constant pitch P (FIG. 4), which can be predetermined and which is indicatively comprised between about 600 mm and about 2,500 mm. In the example embodiment given here the pitch P is 1,150 mm, which is one of the standard measurements in the field of boxes for packaging.

The machine10comprises a fixed metal structure13(FIG. 1) or frame, in the upper part of which a feed unit15is mounted, suitable to feed forward continuously the creased tape11, arriving for example directly from a production plant of the known type and not shown in the drawings, at a determinate very high speed of advance V, even higher than 3.3 m/sec, which corresponds to more than 200 m/min. In particular, the feed unit15comprises, in its end part, a plurality of feed rolls16and a comb-shaped terminal slide18, which is inclined downward by an angle a (FIG. 2), adjustable and comprised between about 9° and about 20°, with respect to a horizontal plane and defines the direction of feed of the creased tape11.

Downstream of the feed unit15a folding device20(FIGS. 1 and 2) is disposed, suitable to fold in a zigzag manner the creased tape11along its transverse creasings12(FIG. 3). The folding device20, which will be described in detail hereafter, is similar to the one described in the above mentioned Italian patent for industrial invention N° 1.374.280, included here in its entirety as a reference, even though it contains new and original technical characteristics compared thereto, which will be shown hereafter and which have solved the technical problems of the known machine in a surprising way.

Below the folding device20a collection device50(FIGS. 1,2,3and10) is disposed, suitable to vertically convey the creased tape11folded in a zigzag manner, in order to stack it and form a continuous pile, or stack, with a determinate height, for example 1,000-1,200 mm. The collection device50will also be described in detail hereafter.

The folding device20(FIGS. 1,2and3) comprise four parallel pairs of main arms, respectively21,22,23and24, of the same length and disposed in a cross, which are attached to a central bar25rotating in a clockwise direction, that is, consistent with the direction of feed of the creased tape11, around a central axis of rotation Z, by means of an electric motor30mounted on the frame13.

At the peripheral end of each pair of main arms21,22,23and24and toward the inside thereof, a corresponding parallel pair of secondary arms31,32,33and respectively34are pivoted on pins26,27,28and respectively29, the secondary arms being shorter than the main arms21,22,23and24and rotatable in an opposite direction to the latter, that is, in an anti-clockwise direction.

Between the peripheral ends of each of the four pairs of secondary arms31,32,33and34a folding rod41,42,43and respectively44is disposed, parallel to the central axis of rotation Z and therefore transverse to the direction of feed of the creased tape11.

The radius R1(FIG. 2) of the main arms21,22,23and24, between the central axis of rotation Z and the axis of each pin26,27,28, and29is substantially equal to pitch P, or a little less than it (for example 1,130 mm). Moreover, the peripheral speed of the pins26-29is proportional to the speed of advance V of the creased tape11, and in this case, slightly less than it, for example ⅕ less than V. The radius R2of the secondary arms31,32,33and34is instead less than half the radius R1and, in this case, about 430 mm.

The secondary arms31,32,33and34receive motion from the rotation of the main arms21,22,23and24, by means of two pairs of chains with rolls36and37, engaging with two corresponding pairs of fixed toothed wheels38and39, coaxial to the central axis of rotation Z. The transmission ratio between the pairs of fixed toothed wheels38and39and those keyed onto the pins26,27,28and29is 2:1, which means that each pair of secondary arms31,32,33and34completes two revolutions around the respective pins26,27,28and29, while the main arms21,22,23and24perform one complete revolution around the central axis of rotation Z. In this way each of the four folding rods41,42,43and44describes a substantially elliptical trajectory T in space. Advantageously the major axis X of the latter is horizontal, or substantially horizontal, while the minor axis Y is vertical, or substantially vertical.

The lower end of the terminal slide18is disposed in a position very near to the fourth quadrant of the trajectory T and almost tangent to it, so that the direction of feed of the creased tape11intersects the trajectory T exactly in the fourth quadrant of the latter.

In consideration of the sizes of the radiuses R1of the main arms21,22,23and24and R2of the secondary arms31,32,33and34, as well as their peripheral speeds, each of the folding rods41,42,43and44is able to intercept the creased tape11every two creasings12of the latter, that is every two pitches P. In this way, each folding rod41,42,43and44is able to fold the creased tape11, thrusting it toward the outside, in correspondence to alternate creasings12, while the creased tape11itself, because of the particular movement of the folding rods41,42,43and44is subjected to folding toward the inside in correspondence to the creasings12intermediate to those contacted by each folding rod41,42,43and44. Consequently, the creased tape11can be folded in an alternate direction, assuming the desired zigzag development.

We must point out that, according to an innovative feature of the present invention, the timing of the main arms21,22,23and24with respect to the secondary arms31,32,33and34is essential and decisive to obtain a zigzag folding which is reliable and constant over time, even at high speeds (more than 3 m/sec) and also with very wide creased tapes (wider than 3 m). This timing provides that two opposite folding rods, for example42and44, must be on the major axis X and face toward the outside when the corresponding main arms and opposite secondary arms, for example22and24, respectively32and34, are also aligned with the major axis X, while at the same time the other two folding rods for example41and43must be on the minor axis Y and face toward the inside, when the corresponding main and secondary arms, for example21and23, respectively31and33, are also aligned with the minor axis Y.

FIGS. 3 to 8show the different operating steps of the folding device20, which will be described in detail hereafter.

The collection device50(FIG. 1) comprises a horizontal support plane51, vertically mobile between two vertical containing sides52and53(FIG. 10) of the fixed structure13, which define a stacking chamber54, by means of a second electric motor55.

The vertical axis W passing through the center of the stacking chamber54defines the stacking axis of the collection device50and intersects the trajectory T in a second quadrant of the latter, opposite the fourth quadrant of the same trajectory T with respect to the central axis of rotation Z of the folding device20.

A conveyor belt56(FIG. 1) is mounted on the support plane51, for example of the rolling shutter type, on which the pile or stack that the creased tape11forms after having been folded by the folding device20is suitable to rest.

The conveyor belt56is selectively drivable by a third electric motor57to laterally discharge the pile of creased tape11folded in a zigzag manner, when the support plane51is in its lowest position (shown with a dotted line inFIG. 10).

The collection device50also comprises, in its upper part, two lateral walls58and59(FIG. 10) disposed opposite one another and on the side where the creasings12of the creased tape11are when it is folded in a zigzag manner. A motorized mechanism60is associated to each of the two lateral walls58and59, able to make them oscillate with respect to corresponding horizontal pins61.

Three compressed air ejector units62(FIG. 2), of the known type and not described in detail, are disposed one above the folding device20, in correspondence to the first quadrant of the trajectory T, about 50 cm therefrom, one inside the interception element65, and one inside the lateral wall59of the collection device50. The three ejector units62are suitable to work in pulses, timed with the angular position of the folding device20to promote the folding and stacking of the creased tape11.

Between the folding device20and the collection device50, the machine10comprises an interception element65(FIGS. 2 and 3) formed by a series of parallel bars, suitable to act as a first-start plane for the creased tape11, and mobile between a first operating position, shown inFIG. 2, in which it is substantially interposed between the folding device20and the collection device50, in order to intercept the head of the creased tape11which is arriving from the feed unit15, and a second operating position, shown inFIG. 3, in which it is displaced on one side and in an almost vertical position, in order not to interfere with the creased tape11.

In particular the interception element65is attached to an arched structure66sliding on rollers68mounted rotatable on the fixed structure13and is commanded by a pair of fluid-dynamic pistons69.

Between the interception element65and the collection device50a comb-shaped horizontal support70is disposed, which is suitable to temporarily support the stack of creased tape11which is forming, during the step of removing the stack previously formed in the collection device50.

In particular, the horizontal support70is mobile both horizontally, by means of a first movement mechanism71commanded by a fourth electric motor72, between a forward position (FIGS. 2 and 3) and a retracted position (FIG. 10), and also vertically, by means of a second movement mechanism73commanded by a fifth electric motor75, between a raised position and a lowered position (both shown with a dotted line inFIG. 10). The details of the movement mechanisms71and73are easily understandable by a person of skill in the art and are not described in detail here.

The machine10also comprises a cutting device80(FIG. 10) disposed under the folding device20and above the collection device50, in order to selectively cut the creased tape11, for example when the stack in the collection device50has reached a desired height.

In this case, the cutting device80(FIG. 11) comprises two horizontal shutters81,82, opposite each other, ending with two wedges slightly offset with respect to each other and each mobile between an open position (FIGS. 3 to 8), in which they are retracted with respect to the passage area of the tape11, and an operating position (FIG. 9) in which they pinch the creased tape11in order to cut it under them.

The cutting device80also comprises a cutting unit83, mounted on the lower part of the shutters82(on the right inFIG. 2) and in turn comprising a rotating blade85(FIGS. 11,12and13) and a counter roller86provided with a circumferential groove88, in which the peripheral edge of the rotating blade85is partly housed, and which defines a matrix which facilitates the cutting of the creased tape11.

The rotating blade85and the counter roller86are mounted rotatable on a slider89sliding on a guide90attached to the shutter82in a transverse direction to the direction of feed of the creased tape11, that is, in the direction indicated by the arrow A inFIGS. 12 and 13. The translation motion of the slider89from a lateral inactive position (FIG. 12), outside the bulk of the creased tape11, as far as an opposite operating end, after having crossed, cutting it, the creased tape11for its entire length, and back, is carried out by a sixth electric motor91by means of a transmission belt92. The rotation of the rotating blade85is on the other hand achieved by the same translation motion of the slider89, by means of a toothed belt93, with its heads attached to the shutter82and engaging with a toothed pinion95(FIG. 13) mounted rotatable on the slider89coaxial with and solid to the rotating blade85. Two small rollers96, also mounted rotatable on the slider89and disposed at the sides of the toothed pinion95, parallel to it, cooperate with the back of the toothed belt93, thus ensuring that the latter engages with the toothed pinion95.

The machine10as described heretofore functions as follows.

First of all it must be underlined that for a correct functioning of the machine10it is essential to synchronize both the angular speed of the main arms21-24of the folding device20with the speed of advance V of the creased tape11, and also the angular timing of the main arms21-24with the position of the transverse creasings14, made upstream of the feed unit15by any known device and not shown in the drawings, and also the reciprocal timing between the main arms21-24and the secondary arms31-34as described above.

When the method to fold the creased tape11in a zigzag manner is started, the machine10is in the initial operating position shown inFIGS. 1 and 2, with the interception element65in the operating position in order to intercept the head of the creased tape11and therefore closing the access to the collection device50below, with the horizontal support70in a high and forward position, with the shutter81(on the left inFIG. 2) forward and with the shutter82(on the right inFIG. 2) retracted.

When the head of the creased tape11reaches the interception element65, the latter is moved by the fluid-dynamic pistons69into its inactive position, which corresponds to a first operating folding position, shown inFIG. 3, and it remains there until the folding process is ended. The shutter81is also retracted, while the horizontal support70remains in the forward position and begins to gradually descend, by means of the second movement mechanism73, as the stack (the pre-stack) of the creased tape11progressively forms.

In this first operating folding position, the main arm21is inclined by an angle β, about 30°, in advance with respect to the minor axis Y of the trajectory T, with the corresponding folding rod41ready to intercept the transverse creasing12which is arriving from the terminal slide18.

In a second operating folding position (FIG. 4), after a rotation by 15° of the folding device20in a clockwise direction, that is, when the angle β is about 15° in advance with respect to the minor axis Y of the trajectory T, the folding rod41has just contacted the creased tape11and begins to fold it upward in correspondence to the corresponding transverse creasing12.

The folding device20, continuing to rotate in a clockwise direction, takes the main arm21, in sequence, first into a third operating folding position (FIG. 5), in which it is aligned with the minor axis Y of the trajectory T, then into a fourth operating folding position (FIG. 6), in which angle β is about 15° behind with respect to the minor axis Y of the trajectory T, then into a fifth operating folding position (FIG. 7), in which angle β is about 30° behind with respect to the minor axis Y of the trajectory T, and finally into a sixth operating folding position (FIG. 8), in which angle β is about 45° behind with respect to the minor axis Y of the trajectory T. It should be noted that in the passage from the second operating folding position to the sixth operating folding position (FIGS. 4 to 8) the transverse creasing12adjacent to the one intercepted by the folding rod41is not affected by any element of the folding device20, and therefore, because of the particular movement of the secondary arms31-34, the creased tape11folds in the opposite direction, thus disposing itself in a zigzag manner.

In the sixth operating folding position of the main arm21, the main arm24adjacent to it is inclined by an angle of 45° in advance with respect to the minor axis Y of the trajectory T, ready to intercept the creased tape11in proximity to another transverse creasing12, after another rotation of 15°, when this too will be in the first operating folding position as described above.

It should be noted that every folding rod41-44, because of its own satellite-type motion, varies its speed with respect to the creased tape11, so that in a first sector, which begins from the first operating folding position (FIG. 3) and ends after a rotation of 90° (position in which the folding rod42is inFIG. 3), the folding rod41-44rotates at a speed substantially equal to the speed of advance V of the creased tape11, and then progressively diminishes to zero, when it is in its horizontal position between the first and the second quadrant of the trajectory T. Then the speed of the folding rod41-44progressively increases until it arrives in a third sector (offset by 180° with respect to the first sector).

In this way, each folding rod41-44contacts the creased tape11in correspondence to one of its transverse creasings12, it accompanies it at the same speed V for all of the first sector, then slows down and zeroes its relative speed, and then accelerates to let the creased tape fall, already folded, into the stack below.

As the creased tape11gradually folds in a zigzag manner and forms the pre-stack on the horizontal support70, the latter is lowered so as to bring it into proximity to the support plane51, which at the beginning was in the maximum raised position shown with a dotted line inFIG. 10. The horizontal support70is then taken into the retracted position, by means of the first movement mechanism71, so that the pre-stack just formed rests on the support plane51below, which is then moved downward to the lower position, at the base of the collection device50, shown with a continuous line inFIG. 10. In the meantime, to facilitate the formation of the stack, the motorized mechanisms60are driven in order to oscillate the lateral walls58and59with respect to their horizontal pins61.

When the stack of creased tape11is completed, the latter is cut, without stopping its advance toward the folding device20, carrying out a so-called “cut on the fly”.

To do this, the two shutters81and82are made to advance one toward the other and taken to the operating cutting position shown inFIGS. 9 and 11, so that the creased tape11remains pinched between their wedged ends.

The cutting device80is then activated and in particular the electric motor91, which by means of the transmission belts92makes the slider89translate transversely to the creased tape11, which is thus held between the counter roller86and the rotating blade85and cut by the latter in a few seconds. The slider89, after carrying out the complete outward travel and cutting the creased tape11, is kept in that position, outside the transverse bulk of the creased tape11; the horizontal shutters81and82are then drawback toward their position shown inFIG. 3, in order to immediately allow the normal flow of the creased tape11toward the collection device50. The slider89is then returned to its initial position (FIG. 12), remaining outside the transverse bulk of the creased tape11for the whole of the return travel.

Once the cutting operation of the creased tape11has been completed, the conveyor belt56is driven (FIGS. 1 and 10) of the collection device50in order to discharge the stack toward conveying means of the known type and not shown in the drawings. During this operation to discharge the stack, the horizontal support70is returned to its initial position, at the top and forward (FIG. 3), that is, below the creased tape11which has just been cut, so that the folding cycle described above can be repeated.

Once the discharge of the stack by the conveyor belt56has been completed, the support plane51is returned to its raised position, to be ready to receive another pre-stack of creased tape11which in the meantime is forming on the horizontal support70, thus ensuring the continuous functioning of the machine10, without having to stop the folding device20.

It is clear that modifications and/or additions of parts may be made to the machine10as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of automated machines for folding and stacking in a zigzag manner creased tapes made of a sufficiently rigid material, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.