-
It is the object of the present invention a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper.
-
It is also an object of the present invention a method for drilling bar-shaped tobacco industry articles wrapped in a wrapper.
-
In the tobacco industry, performing a series of laser drillings on wrapped articles or sticks is known, so as to regulate the quantity of air entering the article during use, thus allowing a smoother and more controlled smoking experience and a more uniform heat distribution.
-
To date, drilling stations are known comprising a transport cylinder provided with a sequence of seats, each configured to accommodate a respective article. The known stations further comprise at least one drilling device, for example a laser drilling device, arranged in a drilling area and configured to operate the drilling of the wrapper of an article retained in the respective seat and arranged in the drilling area.
-
The known stations further comprise an counter-roller arranged in the drilling area above the article and configured to cause a rolling of the article along a bottom wall of the respective seat.
-
More in detail, each article arrives in the drilling area and abuts against a first (front) wall of the seat in which it is accommodated. In such situation, the counter-roller imparts a thrust to the article, which rolls along the bottom wall. The combined action of the transport cylinder and counter-roller causes the article, during drilling, to take a centered position with respect to the seat in which the extension axis of the article is substantially vertically aligned to the axis of the transport cylinder and to that of the counter-roller. In such a situation, the article, in the drilling area, rotates about the extension axis thereof, so that the drilling device may act along the entire angular extension thereof, thus forming a plurality of angularly distributed drillings.
-
More in detail, in order for the article, in the drilling area, to remain stationary along the advancement path but rotate about the axis thereof, so as to be able to perform the annular drilling, it is preferable that the tangential speed of the counter-roller be equal in magnitude and opposite in direction with respect to that of the transport cylinder.
-
In known solutions, the seat has, at least at the initial and final positions of the article (thus at the first wall and at a second rear wall for stopping the rolling), suction seats for the retention of the article by pneumatic suction. It is also known, in certain solutions, to provide on the counter-roller an activation protrusion or tooth which engages the article, thus forming an initial impact which causes it to detach from the first wall, overcoming the pneumatic suction.
-
To avoid errors in the drilling, the need is therefore particularly felt for the article to be correctly positioned in the drilling area. This proves particularly complex when the station is required to increase the production speed thereof. In such a situation, an increase in the rotation speed of the transport cylinder may lead to initial impacts, between the tooth and the article, excessively vigorous to the point of causing the loss of control of the position of the article which, therefore, rolls with the longitudinal axis thereof arranged in a position spaced apart from the position provided (and generally rearward), thus causing an error in the drilling.
-
In other words, as the rotation speed of the transport cylinder increases, there is a risk of generating an erroneous positioning of the article in the rolling configuration. Such positioning, moreover, is not predictable a priori since it has been observed that not only is the relationship between speed and positioning deviation not linear, but also the parameters involved are many (speed of the transport cylinder, size and shape of the tooth of the counter-roller, material of the article, magnitude of the pneumatic suction and many others) and, in addition, the phenomenon is not always systematic and therefore preset correction or feedback laws, capable of solving the issue, may not be implemented.
-
The technical task of the present invention is therefore to provide a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper and a method for drilling bar-shaped tobacco industry articles wrapped in a wrapper which are capable of overcoming the drawbacks emerged from the prior art.
-
It is therefore the object of the present invention to provide a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper, which ensures correct positioning of the articles during drilling, essentially independently of the operating speed of the station itself.
-
It is therefore a further object of the present invention to provide a method for drilling bar-shaped tobacco industry articles wrapped in a wrapper, which is precise and reliable throughout the working speed range of the station itself.
-
The specified technical task and the specified objects are substantially achieved by a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper, comprising the technical features set forth in claim 1 and/or in one or more of the appended claims, and by a method for drilling bar-shaped tobacco industry articles wrapped in a wrapper, comprising the technical features set forth in claim 9 and/or in one or more of the joined claims.
-
In particular, the specified technical task and the specified objects are achieved by a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper in accordance with the present invention.
-
The station comprises a transport cylinder comprising a sequence of seats, each configured to accommodate a respective article.
-
The transport cylinder is configured to rotate about a rotation axis so as to advance each article along an advancement path passing through a drilling area.
-
Each seat is configured to orient the respective article so that the extension axis of the article is parallel to the rotation axis of the transport cylinder.
-
Each seat extends between a first side wall and a second side wall for an angular extension about the rotation axis such that, upstream of the drilling area, each article abuts against the first side wall of the seat and that, downstream of the drilling area, each article abuts against the second side wall.
-
The station further comprises at least one laser drilling device arranged and configured to operate the drilling of the wrapper of an article received in the respective seat and arranged in the drilling area.
-
The station further comprises a counter-roller arranged in the drilling area above the article and configured to cause a rolling of the article, along a bottom wall of the respective seat, from the first side wall toward the second side wall.
-
The counter-roller is operated by a respective motor.
-
Preferably, the station comprises a motor configured to operate the counter-roller.
-
The station further comprises a detection device configured to perform at least one optical inspection of a front surface of each article in the drilling area.
-
The station further comprises a control unit connected to the detection device and to the motor of the counter-roller, and configured to control the motor of the counter-roller according to the outcome of the optical inspection carried out.
-
Preferably, the control unit is configured to determine, on the basis of the outcome of the optical inspection, the actual position of at least one article in the drilling area along the advancement path.
-
Preferably, the control unit is configured to compare the position with a reference position, so as to determine a deviation between the actual position and the reference position.
-
Preferably, said detection device is configured to perform a predetermined number of inspections. In such a situation, the control unit is configured to determine an actual mean position value based on the predetermined number of inspections.
-
Preferably, the deviation is determined between the actual mean position and the reference position.
-
Preferably, the predetermined number of inspections is defined by at least one of:
- a plurality of optical inspections carried out on the article itself;
- a plurality of optical inspections, each carried out on a respective single article;
- a plurality of optical inspections carried out on a plurality of articles, each article is subjected to a plurality of optical inspections.
-
Preferably, the control unit is configured to vary an angular phase of the motor of the counter-roller and/or a speed of rotation of the counter-roller according to the outcome of the optical inspection carried out.
-
Preferably, once the actual mean position value based on the predetermined number of inspections has been determined and once the deviation between the motor of the counter-roller and/or a speed of rotation of the counter-roller has been obtained, the control unit varies, on the basis of the above information, the angular phase of the motor of the counter-roller and/or the speed of rotation of the counter-roller. By doing so, it is possible to advance or delay the interaction of the counter-roller with the article transiting in the drilling area so as to avoid the mispositioning thereof during the drilling.
-
Preferably, the optical inspection device comprises a laser emitter configured to emit a laser blade at a diameter of the article transiting in the drilling area.
-
Even more preferably, the laser blade lies on a plane tangential, or parallel to a plane tangential to the transport cylinder in the drilling area.
-
In such a situation, in accordance with a first possible embodiment, the position data is calculated by the control unit as the position of at least one intersecting point between the laser blade and the outer profile of the front surface of the article.
-
In accordance with a second possible embodiment alternative to the first one, the position data is calculated by the control unit as the position of the midpoint between the two intersecting points between the laser blade and the outer profile of the front surface of the article. Preferably, the laser blade has a thickness between 5 m and 200 m, preferably equal to 50 m, and/or a width comprised between 5mm and 100mm, preferably equal to 30mm.
-
The specified technical task and the specified objects are further achieved by a method for drilling bar-shaped tobacco industry articles, wrapped in a wrapper, in a laser drilling station, in accordance with the present invention. Preferably, the aforesaid laser drilling station is made in accordance with what described above.
-
The method comprises a step of transporting a sequence of articles along an advancement path passing through a drilling area. Each article is accommodated in a seat of a transport cylinder.
-
The method further comprises a step of drilling, by means of a laser drilling device, the wrapper of the article retained in the respective seat and arranged in the drilling area, and a step of operating a counter-roller by means of a motor to cause, in the drilling area, a rolling of the article, along a bottom wall of the respective seat, from a first side wall towards a second side wall. The drilling of the article is carried out during the rolling of the article in the drilling area. Thereby, by means of a stationary laser drilling device, it is possible to perform drillings that are angularly distributed about the longitudinal axis of the article.
-
The method comprises a step of carrying out, by means of a detection device, an optical inspection of a front surface of each article in the drilling area and a step of controlling, by means of a control unit connected to the detection device and to the motor of the counter-roller, the motor of the counter-roller according to the outcome of the optical inspection carried out.
-
Preferably, the method further comprises a step of determining, on the basis of the outcome of the optical inspection, the actual position of at least one article in the drilling area along the advancement path.
-
Preferably, the method further comprises a step of comparing the position with a reference position so as to determine a deviation between the actual position and the reference position.
-
Preferably, the step of carrying out an optical inspection is repeated a predetermined number of times.
-
Preferably, the method comprises a step of determining an actual mean position value based on the predetermined number of inspections. In such a situation, the deviation is determined between the actual mean position and the reference position.
-
Preferably, the step of controlling comprises a step of varying an angular phase of the motor of the counter-roller and/or a speed of rotation of the counter-roller according to the outcome of the optical inspection carried out.
-
Preferably, the step of performing an optical inspection comprises a step of emitting a laser blade at a diameter of the article transiting in the drilling area.
-
In particular, the laser blade lies on a plane tangential, or parallel to a plane tangential to the transport cylinder in the drilling area.
-
Preferably, the step of determining an actual position is performed by calculating the position of at least one intersecting point between the laser blade and the outer profile of the front surface, or by calculating the position of the midpoint between the two intersecting points between the laser blade and the outer profile of the front surface.
-
Further features and advantages of the present invention will become more apparent from the indicative, and thus non-limiting, description of an embodiment of a laser drilling station for bar-shaped tobacco industry articles wrapped in a wrapper, and of a method for drilling bar-shaped tobacco industry articles wrapped in a wrapper.
-
This description will be presented below with reference to the appended drawings, provided purely for indicative and therefore, non-limiting purposes, in which:
- Figure 1 shows a perspective view of the station of the present invention, in which the counter-roller has been removed;
- Figure 2 shows an enlargement of Figure 1;
- Figure 3A shows a diagrammatic front view in which an article is erroneously positioned in the drilling area;
- Figure 3B shows a diagrammatic front view in which an article is correctly positioned in the drilling area;
- Figure 4 shows a diagrammatic perspective view of the station of the present invention, in which the drilling device has been removed.
-
With reference to the attached Figures, a laser drilling station for bar-shaped tobacco industry articles, wrapped in a wrapper, has been indicated with "S".
-
The station "S" comprises a transport cylinder 100 comprising a sequence of seats 101, each configured to accommodate a respective article "A".
-
The transport cylinder 100 is configured to rotate about a rotation axis "X" so as to advance each article "A" along an advancement path passing through a drilling area "P". As shown, for example, in Figure 1, each seat 101 is configured to orient the respective article "A" so that the extension axis of article "A" is parallel to the rotation axis "X" of the transport cylinder 100.
-
Each seat 101 extends between a first side wall 101a and a second side wall 101b for an angular extension about the rotation axis "X" such that, upstream of the drilling area "P", each article "A" abuts against the first side wall 101a of the seat 101 and that, downstream of the drilling area "P", each article "A" abuts against the second side wall 101b.
-
Preferably, each seat 101 comprises a bottom wall 101c interposed between the first and the second side walls 100a, 100b, and configured to support the article "A".
-
Preferably, the bottom wall 101c of each seat 101 is defined by a corresponding portion of the outer shell of the transport cylinder 100.
-
The station "S" further comprises at least one laser drilling device 200 arranged and configured to operate the drilling of the wrapper of an article "A" received in the respective seat 101 and arranged in the drilling area "P". Preferably, the station "S" comprises two laser drilling devices 200 placed side by side along a direction parallel to the rotation axis "X".
-
Advantageously, the fact of having two laser drilling devices 200 arranged side by side allows a drilling to be performed on articles "A" of double length. Preferably, the station "S" further comprises an internal suction device (not shown) arranged inside the transport cylinder 100 and configured to apply, through at least one suction opening made on the transport cylinder 100, a suction action so as to remove at least part of the particles deriving from the drilling of the wrapper in the drilling area "P".
-
Preferably, the internal suction device comprises a plurality of suction openings arranged in sequence along a circumferential perimeter of the transport cylinder 100 and made on an outer shell of the transport cylinder 100.
-
By doing so, the bottom wall 100c of each seat 101 of the transport cylinder 100 is associated with respective suction openings. In such a situation, the suction action allows retaining each article "A" in the respective seat 101 and, when the seat 101 is passing through the drilling area "P", the suction openings suction the particles resulting from the drilling.
-
The station "S" further comprises a counter-roller 300 located in the drilling area "P", above the article "A".
-
The counter-roller 300 is configured to cause a rolling of the article "A", along the bottom wall 101c of the respective seat 101, from the first side wall 101a toward the second side wall 101b. Figure 2 shows the drilling area "P", where the article, in a position still abutting against the first side wall 101a, is shown in dashed line, while the same article is shown in solid line in a subsequent rolling step.
-
The counter-roller 300 is operated by a respective motor 600 (Figure 4).
-
The counter-roller 300 rotates about a rotation axis "Y" parallel to the rotation axis "X" of the transport cylinder 100.
-
In particular, the rotation axis "Y" of the counter-roller 300 is vertically aligned with the rotation axis "X" of the transport cylinder 100.
-
Preferably, the counter-roller 300 comprises at least one thrust tooth 300a located on the outer surface of the counter-roller 300 and configured, during the rotation of the counter-roller 300, to impart a thrust to an outer lateral surface of the article "A" so as to initiate the rolling thereof.
-
More in detail, the thrust tooth 300a is configured to push the article "A" away from the first side wall 101a towards the drilling area "P".
-
The counter-roller 300 may further comprise at least one recess (not shown) made as a radially outer depression of the counter-roller 300, having a predetermined angular extension and angularly offset with respect to the thrust tooth 300a. Such recess has the function of disengaging the counter-roller 300 from the article "A" at instants in which a rolling of the article "A" itself is not operable (thus, in the passage between one article and the other).
-
In an embodiment, the counter-roller 300 comprises two thrust teeth 300a, diametrically opposite each other. In such an embodiment, the counter-roller 300 comprises two recesses diametrically opposite each other.
-
The counter-roller 300 rotates at a tangential speed equal to the tangential speed of the transport cylinder 100, but in a direction opposite the direction of rotation of the feeding cylinder 100. This causes that the simultaneous engagement of an article "A" with the shell of the transport cylinder 100 and with the counter-roller 300 in a stationary position, but rotating about the longitudinal axis thereof.
-
In use, upstream of the drilling area "P", each article "A" abuts against the first side wall 101a of the seat 101. When the article "A" reaches the counter-roller 300, arranging itself in the drilling area "P", the thrust tooth 300a of the counter-roller 300 imparts a thrust against the lateral surface of the article "A", so as to cause it to detach from the first side wall 101a and roll toward the second side wall 101b. In such a situation, article "A" is rolling along the bottom wall 101c between the transport cylinder 100 and the counter-roller 300 in the drilling area "P".
-
In such a situation, the tangential speeds of the counter-roller 300 and of the transport cylinder 100 being equal in magnitude and opposite in direction, the article "A" rotates about the extension axis thereof without advancing along the advancement path, therefore rolling on the bottom wall 101c, so that the wrapper may be circumferentially drilled by the at least one laser drilling device 200.
-
The article "A" rotates about the extension axis thereof without advancing along the advancement path up to the instant in which the recess of the counter-roller 300 is in proximity to article "A". In such a situation, the contact between article "A" and the counter-roller 300 ceases, and the synchronization with the transport cylinder 100 causes article "A" to stop rolling, coming to rest on the second side wall 101b.
-
In accordance with the invention, the station "S" further comprises a detection device 400 configured to carry out at least one optical inspection of a front surface "F" of each article "A" in the drilling area "P".
-
Preferably, as shown in the accompanying Figures, the detection device 400 faces the drilling area "P" so as to be counter-facing the front surface "F" of each article "A" in the drilling area "P".
-
In use, therefore, when article "A" reaches the drilling area "P", the detection device 400 carries out an optical inspection of the front surface "F" thereof (Figure 2).
-
The station "S" further comprises a control unit 500 connected to the detection device 400 and to the motor 600 of the counter-roller 300, and configured to control the motor 600 of the counter-roller 300 according to the outcome of the optical inspection performed.
-
In other words, the detection device 400 is configured to send to the control unit 500 the outcome of the optical inspection carried out, and the control unit 500, after suitably processing such outcome, is configured to send a corresponding control command to the motor 600 of the counter-roller 300. By doing so, it is possible to perform a corrective action in the operation of the counter-roller 300 such that it interacts with the articles "A" so as to cause them to be correctly positioned in the drilling area "P", as it will be described in detail below.
-
Preferably, the control unit 500 is configured to determine, on the basis of the optical inspection, the actual position of at least one article "A" in the drilling area "P" along the advancement path, and to compare the position with a reference position so as to determine a deviation between the actual position and the reference position.
-
In other words, by means of the detection device 400, an optical inspection is carried out, which is sent to the control unit 500 that, on the basis of such optical inspection, determines the position actually occupied by the article "A" in the drilling area "P". The control unit 500 further performs a comparison between the position actually occupied by the article "A" and a reference position, i.e., an ideal position that the article "A" should take in the drilling area "P".
-
Preferably, the reference position is a position in which the article "A" is arranged in the optimal position to receive the drilling by rotating on itself.
-
In an embodiment, the reference position is a position in which the article "A" has the longitudinal axis thereof lying in a plane joining the rotation axis of the counter-roller 300 and the rotation axis "X" of the transport cylinder 100 (Figure 3B).
-
Preferably, the detection device 400 is configured to perform a predetermined number of inspections, in particular with a predetermined detection frequency.
-
In an embodiment, the detection device 400 is configured to perform a kind of sampling in which it optically inspects a sample number of articles "A". In such a situation, the control unit 500 is configured to determine an actual mean position value based on the predetermined number of inspections. By doing so, the deviation is determined between the actual mean position and the reference position.
-
In a different embodiment, the detection device 400 is configured to operate on all articles "A".
-
In both cases, the detection device 400 performs a predetermined number of inspections so that the control unit 500 determines a corresponding number of position data identifying the position actually occupied by the inspected articles "A". The control unit 500 therefore calculates an actual mean position based on the inspections performed, and determines the deviation between the calculated actual mean position and the reference position. By so doing, on the basis of such deviation, the control unit 500 controls the motor 600 of the counter-roller 300 so that, during steady-state use of the station "S", all the articles "A" occupy a position, in the drilling area "P", such that the drilling operation may be correctly performed. This implements a position control based on the "trend" of a predetermined number of articles.
-
Advantageously, by calculating the deviation as the difference between the actual mean position, obtained on the basis of the positions of a sample number of articles "A" (or of all the articles), and the reference position, there is the certainty that all the articles "A" are correctly positioned in the drilling area "P", thus avoiding that an accidental erroneous positioning of a single article may give rise to an (undesired) correction of an indeterminate number of subsequent articles.
-
Preferably, the predetermined number of inspections is defined by at least one of:
- a plurality of optical inspections carried out on the article "A" itself;
- a plurality of optical inspections, each carried out on a respective single article "A";
- a plurality of optical inspections carried out on a plurality of articles "A", each article "A" is subjected to a plurality of optical inspections.
-
In the first case, the mean position of each article is determined (thus absorbing any fluctuations that each article may follow during rolling, for example caused by asperities - knurls - of the rolling surface).
-
In the second case, the trend of a plurality of articles is monitored, thus reducing the contribution from one or more (however few) possible mispositioned articles.
-
In the third case, albeit computationally more burdensome, the benefits of the first and second cases are obtained.
-
With reference to the Figures 3A and 3B, by way of explanation and not of limitation, it is assumed that the detection device 400 carries out two inspections (i.e., that the predetermined number of inspections is equal to two) and that such inspections are processed by the control unit 500. In such a situation, from the processing performed on the inspection of the article in Figure 3A, it will be determined that the actual position of article "A" is different from the reference position, and therefore there is a deviation. From the processing performed on the inspection of the article of Figure 3B, it will instead be obtained that the actual position of the article "A" is substantially identical to the reference position and, therefore, there is a substantially null deviation. In such a situation, the control unit 500 determines, on the basis of the two inspections performed, the actual mean position value and determines the deviation between the actual mean position and the reference position. Subsequently, it sends to the motor 600 of the counter-roller 300 a control command based on such deviation, so that, during the steady-state operation of the station "S", all the articles "A" occupy, in the drilling area "P", a position suitable for drilling.
-
Preferably, the control unit 500 is configured to send a command to vary an angular phase of the motor 600 of the counter-roller 300 and/or a command to vary a rotation speed of the counter-roller 300.
-
In greater detail, once the deviation has been determined, it is possible to send to the motor 600, by means of the processing unit 500, a corrective action to be carried out so that each article "A" transiting the drilling area "P" occupies a position such as to allow a correct drilling to be carried out. Such corrective action may consist in a modification of the angular phase of the motor 600, for example to advance or delay the impact between the thrust tooth 300a and the article "A", and/or a variation of the rotation of the counter-roller 300.
-
In the embodiment described in the accompanying Figures, the optical inspection device 400 comprises a laser emitter configured to emit a laser blade "L" at a diameter of the article "A" transiting the drilling area "P".
-
In particular, the laser blade "L" lies on a plane tangential, or parallel to a plane tangential to the transport cylinder 100 in the drilling area "P" (Figure 2).
-
In such a situation, the optical inspection occurs by emitting the laser blade "L" toward the front surface "F" of the article "A" so that it is at a diameter of the article "A" placed in the drilling area "P" (Figure 2).
-
Preferably, the laser blade "L" has a thickness between 5 m and 200 m, preferably equal to 50m, and/or a width between 5mm and 100mm, preferably equal to 30mm.
-
Still with reference to the embodiment described, the position value is calculated by the control unit 500 as:
- the position of at least one intersecting point between the laser blade "L" and the outer profile "E" of the front surface "F"; or
- the position of the midpoint between the two intersecting points between the laser blade "L" and the outer profile "E" of the front surface "F".
-
Furthermore, it is an object of the present invention a method for drilling bar-shaped tobacco industry articles "A", wrapped in a wrapper, in a laser drilling station "S", preferably, a station "S" as described above.
-
The method comprises a step of conveying a sequence of articles "A" along an advancement path passing through a drilling area "P". Each article "A" is accommodated in a seat 101 of a transport cylinder 100.
-
The method comprises a step of drilling, by means of a laser drilling device 200, the wrapper of the article "A" retained in the respective seat 101 and arranged in the drilling area "P".
-
Preferably, the step of drilling is carried out while the article "A" rotates about the extension axis thereof, without moving along the advancement path, therefore while rolling along the seat 101.
-
The method further comprises a step of operating the counter-roller 300 by means of the respective motor 600 in order to cause, in the drilling area "P", a rolling of the article "A" along the bottom wall 101c of the respective seat 101, from the first side wall (101a) to the second side wall 101b.
-
Preferably, the step of operating the counter-roller 300 is operated before the step of drilling. The counter-roller 300, in fact, initially causes a separation of the article "A" from the first side wall 101a and, preferably, only subsequently is the drilling step carried out.
-
The method further comprises a step of operating, by means of the detection device 400, the optical inspection of the front surface "F" of each article "A" in the drilling area "P".
-
Preferably, the step of operating the optical inspection comprises a step of emitting a laser blade "L", directing it at a diameter of the article "A" transiting in the drilling area "P".
-
In particular, the laser blade "L" lies on a plane tangential, or parallel to a plane tangential to the transport cylinder 100 in the drilling area "P".
-
The method further comprises a step of controlling, by means of a control unit 500 connected to the detection device 40 and to the motor 600 of the counter-roller 300, the motor of the counter-roller 300 according to the outcome of the optical inspection carried out.
-
Preferably, the step of controlling comprises a step of varying an angular phase of the motor 600 of the counter-roller 300 and/or a speed of rotation of the counter-roller 300, according to the outcome of the optical inspection carried out.
-
Preferably, the method comprises a step of determining, on the basis of the outcome of the optical inspection, the actual position of at least one article "A" in the drilling area "P" along said advancement path, and a step of comparing the position with a reference position so as to determine a deviation between the actual position and the reference position.
-
Preferably, in the case of use of an emitter of a laser blade "L", the step of determining an actual position is carried out by calculating:
- the position of at least one intersecting point between the laser blade "L" and the outer profile "E" of the front surface "F"; or
- the position of the midpoint between the two intersecting points between the laser blade "L" and the outer profile "E" of the front surface "F".
-
In accordance with a preferred embodiment, the step of carrying out an optical inspection is repeated a predetermined number of times. By doing so, the method comprises a step of determining an actual mean position value based on the predetermined number of inspections. In such a situation, the deviation is determined between the actual mean position and the reference position.
-
In use, upstream of the drilling area "P", each article "A" abuts against the first side wall 101a of the seat 101 and is advanced along the advancement path. In such a situation, the counter-roller 300 (which preferably rotates continuously) engages the article "A", imparting a thrust against the lateral surface of the article "A" so as to cause it to detach from the first side wall 101a and to roll toward the second side wall 101b.
-
During such rolling, the wrapper is circumferentially drilled by the at least one laser drilling device 200. In such a situation, the detection device 400 carries out the optical inspection and sends the outcome to the control unit 500. The latter processes what is detected by the detection device 400 and determines the actual position of the article "A" in the drilling area "P". Subsequently, the control unit 500 compares the actual position with the reference position. The inspection step, the sending step and the determining step for the actual position with respect to the reference position are repeated for a predetermined number of articles "A" and/or for a predetermined number of times for each article, so as to define a trend or pattern of the deviation of the position of the articles "A" with respect to the reference position. Subsequently, the control unit 500 determines the actual mean position value and the determined deviation between the actual mean position and the reference position, and sends a command to the counter-roller 300 to vary the angular phase of the motor 600 and/or a rotation speed.
-
The present invention achieves the intended objectives by eliminating the drawbacks encountered in the prior art.
-
In particular, by virtue of the possibility of controlling the motor 600 of the counter-roller 300, it is possible to ensure that all articles "A" occupy, during drilling, a correct position in the drilling area "P".