Perforating device for web-shaped materials

Abstract

A punching device (GP) for forming punching lines (P) on a web-like material (N), wherein the punching lines are formed by a predetermined number of punches (F) arranged at intervals of a predetermined value and aligned along a preset punching direction (CD), the punching device being capable of optically detecting the punches (F), configured to acquire an image of the web-like material (N) corresponding to the punching lines (P), and comprising an optical unit (3) connected to a programmable processing unit (4), the processing unit (4) receiving an electrical signal generated by the optical unit (3) in order to issue an error signal indicating an abnormal state regarding the operation of the punching device (GP) according to a comparison between the number of detected punches and the predetermined number of punches.

Description

Technical Field

[0001] The present invention relates to a punching device for web-shaped materials provided with a punching control system.

Background Art

[0002] In particular, but not limited thereto, the system for controlling the punching device for web-shaped materials according to the present invention can be used to control the punching of paper plies supplied to a rewinder in a paper processing step.

[0003] In the paper processing step, generally, paper on a large-diameter reel called a "parent reel" is converted into a plurality of small-diameter logs by a rewinder, and then transverse cutting is performed to obtain rolls of a predetermined length such as toilet paper rolls, kitchen rolls, kitchen towels, etc. It is known that. Upstream of the rewinder, a punching device for forming a transverse punching line on the web-shaped material supplied from the parent reel is arranged. In this way, each roll is formed by a continuous sheet separated by a punching line that facilitates the separation of individual sheets when needed. Generally, the punching device is composed of a blade holding roller to which a plurality of blades are angularly equidistant, and a roller to which a counter blade is attached. Generally, the blade holding roller rotates about its own axis at a predetermined angular velocity, and the counter blade is fixed. The punching line is caused by the periodic contact between the blade and the counter blade.

[0004] Defects may occur in the punching due to wear, breakage, or improper assembly of one or more blades or counter blades, or due to the loss of the reciprocating position of the roller. For example, the number of punches may be less than the required number.

[0005] Patent Document 1 discloses a machine equipped with a punching device for forming punching lines on a web material. The machine includes an optical unit used to count the punching lines so as to count the pages defined by the punching lines for maintenance of the punching elements after a predetermined number of pages are formed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] The main object of the present invention is to provide a punching device control system suitable for automatically detecting the operating state of a punching device by analyzing the punching performed on a web material.

Means for Solving the Problems

[0008] This object is achieved by adopting the idea of realizing a system having the features shown in claim 1 according to the present invention. Other features of the present invention are the subject matter of the dependent claims.

Advantages of the Invention

[0009] According to the present invention, the operating state of a punching device can be monitored through analysis of the punching performed on a web-like material. Also, based on the analysis of the punching, it is possible to automatically adjust the reciprocating positions of the used blade and counter blade in order to correct the detected errors. Furthermore, the control system according to the present invention is relatively low-cost compared to the advantages it provides, and it is also possible to introduce it into existing production factories.

[0010] These and further advantages and features of the present invention will be better understood by those skilled in the art from the following description and the accompanying drawings, which are provided by way of example and should not be considered in a limiting sense.

Brief Description of the Drawings

[0011]

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Mode for Carrying Out the Invention

[0012] The perforating device GP shown as an example in FIGS. 1 to 3 includes a first blade holding roller 1 and a second roller 2 to which a plurality of counter blades are attached.

[0013] A plurality of blades 10A to 10F are evenly distributed and attached to the outer peripheral surface of the blade holding roller 1.

[0014] The blade holding roller 1 is connected to respective electric motors M1 acting on one of its pins 11, and rotates at a predetermined angular velocity about its longitudinal axis A1.

[0015] For example, there are six blades 10A to 10F, but it is understood that the number can be arbitrary according to the web material to be processed and the desired distance between the perforation lines formed on the web material. Generally, for example, the number of blades is 1 to 12.

[0016] In this example, during the perforation of the web material, the second roller 2 is stationary. Preferably, a plurality of counter blades 20 are attached to the roller 2, forming a kind of magazine such that it is not necessary to disassemble the roller 2 when it is necessary to replace the counter blades. With this configuration of the counter roller 2, it is sufficient to simply rotate the roller 2 to bring in an undamaged counter blade 20 in place of a worn or damaged counter blade. Preferably, the counter blade 20 is rectangular and is attached to the side surface of the roller 2 parallel to the longitudinal axis of the roller 2.

[0017] Preferably, the blades 10A - 10F have a spiral shape, and in order to avoid the pressure that may lead to premature breakage of the blades 10A - 10F, the contact between the blades 10A - 10F in use and the counter blade 20 is substantially punctiform and continuous over a long period of time, so the counter blade 20 is stationary.

[0018] The relative positions of the rollers 1 and 2 are adjustable. For example, the first roller 1 is attached to the corresponding fixed support 12 by the respective pins 11, and the second roller 2 is attached to the corresponding movable support 22 by the respective pins 21, whereby the distance of the second roller 2 from the first roller 1 can be adjusted. In FIGS. 1 and 2, for simplicity, the supports 12, 22 are shown only on the side opposite to the motor M1. The support 22 of the roller 2 is connected to the respective actuator 23. For example, the actuator 23 can move the support 22 so as to move the roller 2 parallel to the roller 1, or the actuator 23 can move the support 22 in a differentiated manner so as to change the axial direction of the roller 2 with respect to the roller 1. In FIG. 3, the arrows H, K represent the possible movements of the support 22 controlled by the actuator 23. This structure is known per se.

[0019] The punching device GP forms a punching line P in the lateral direction with respect to the web-shaped material N that passes between the blade and the counter blade during use. In other words, the punching line P is generally oriented along a predetermined direction CD that is perpendicular to the passing direction MN of the web-shaped material N between the rollers 1 and 2. In relation to the rotational speed of the first roller 1 and the advancing speed of the web-shaped material N, a plurality of punching lines P are spaced apart from each other by a predetermined value. The punching line P is formed by a predetermined number of cuts or punches F that are oriented laterally with respect to the web-shaped material N, and the plurality of cuts F are spaced apart from each other by a predetermined value. The mechanism for moving the web-shaped material N is known per se and will not be described in detail. Generally, the movement of the web-shaped material N is determined by the traction exerted on the web-shaped material N by a member intentionally provided in the machine that uses the material itself. For example, in a rewinder for processing paper, the movement of the web-shaped material N is determined by the traction exerted on the web-shaped material N by the take-up roller of the rewinder, or, in the case where the web-shaped material is embossed by the rewinder before being converted into a log, it is determined by the traction exerted on the web-shaped material N by the embossing roller.

[0020] Advantageously, the control system according to the invention comprises an optical unit 3 adapted to optically detect the perforations F in a predetermined control zone ZC of the path followed by the web-like material N downstream of the perforating device GP while the web-like material N moves along the path. The optical unit 3 is configured to acquire an image of the web-like material N corresponding to the perforation line P. For example, the optical unit 3 is a camera. The optical unit 3 is connected to a programmable processing unit 4 that receives the electrical signals generated by the optical unit 3 and processes them according to a programmed processing criterion that includes a comparison between a predetermined number of perforations F of at least one perforation line P and the number of perforations detected by the optical unit 3 on the same perforation line. Depending on the comparison thus made, the processing unit 4 can issue an error signal that can be used to indicate an abnormal state regarding the operation of the perforating device GP.

[0021] For example, as will be further explained below, if the optical unit 3 detects only 10 perforations (NPR = number of detected perforations) on a perforation line P that should have 20 perforations F (NPP = preset number of perforations), the error signal is issued. Alternatively, for example, if the optical unit detects 16 perforations (NPR) on a perforation line P that should have 20 perforations F (NPP) and 4 missing perforations F are consecutive along the perforation line, the error signal is issued. More generally, according to the invention, the perforations F and their positions of each perforation line P are detected, the missing perforations are counted relative to the perforations that the perforation line P should have under the condition that the perforating device operates correctly, and it is checked whether the missing perforations on the perforation line are consecutive. A possible criterion for indicating that the operating state of the perforating device is incorrect is to issue an error signal when NPR ≦ a × NPP (where "a" is a control parameter that can take a predetermined value and can be a value smaller than 1 as a function of the quality level acceptable for the final product).

[0022] For example, "a" can be a value included between 0.50 and 0.95. Again, a possible criterion for indicating an incorrect operating state of the punching device consists in the optical unit emitting an error signal when it detects several consecutive punching omissions (NPC) (punching omissions corresponding to adjacent positions along the inspected punching line) that are greater than a preset threshold value (NPS). Different levels of priority can be assigned to these criteria so that one can play the role of the main control criterion and the other can play the role of the secondary control criterion. For example, the criterion based on the count of the punching can be set as the first control criterion, and the criterion based on the detection of the position of the missing punching can be set as the second control criterion, but it is understood that these roles can be reversed. Also, the above-mentioned control criteria can be combined in the sense that an error signal is emitted when both conditions of NPR ≦ a × NPP and NPC ≧ NPS are satisfied.

[0023] The illuminator 30 is preferably associated with the optical unit 3. As will be further described below, depending on the desired configuration, the illuminator 30 can be arranged on the same side as the optical unit 3 with respect to the web-shaped material N, or on the opposite side.

[0024] Experimental tests conducted by the applicant have shown that when the web-like material N is spread at the detection position, the optical unit 3 can detect the perforation F more accurately. For this purpose, the optical unit 3 is preferably arranged at a point on the path followed by the web-like material N guided on the guide roller 5 (with a radius equal to the radius of the guide roller 5), so that the local traction of the web material passing over the guide roller 5 causes a slight expansion of the perforation F, and thus the contrast between the color of the web-like material N and the color of the guide roller located below it becomes clearer. More generally, the optical unit 3 is arranged at a point on the path followed by the web-like material N, and at this point, it is preferable that the web-like material N passes over a convex surface having a convex portion facing the optical unit 3. In this configuration, the illuminator 30 is arranged on the same side of the web-like material N as the optical unit 3. Such a configuration is represented, for example, in the schematic diagram of FIG. 6.

[0025] In a possible alternative embodiment of the present invention, the illuminator 30 is arranged on the opposite side of the optical unit 3 with respect to the web-like material N.

[0026] In a further alternative embodiment of the present invention, the illuminator 30 can be arranged inside the guide roller 5 or inside the aforementioned convex surface, in which case an opening or surface transparent to light is provided.

[0027] Preferably, the error signal is used to initiate an automatic procedure for identifying one or more components of the punching device (one or more of the blades 10A to 10F or the counter blade 20) whose state may have caused the emission of the error signal. For example, the blades 10A to 10F or the counter blade 20 may be damaged or excessively worn. Alternatively, for example, the relative positions of the blades 10A to 10F and the counter blade 20 may be incorrect in the sense that the distance between the blades 10A to 10F and the counter blade 20 is excessive.

[0028] Furthermore, preferably, the error signal is used to initiate an automatic procedure for correcting the position of a component of the punching device, for example, the position of the counter blade during use. An example of an automatic correction procedure will be described below.

[0029] According to a possible embodiment of the present invention, the processing unit 4 is connected to the first roller 1 by an encoder 40 (only shown in the block diagram of FIG. 7). Accordingly, the processing unit 4 acquires the positions of the blades 10A to 10F, thereby acquiring the position of the perforation line P on the web-like material N as the perforation line is formed. The processing unit 4 controls the activation of the optical unit 3 and synchronously controls the activation of the illuminator 30 via the controller 300 of the optical unit 3 in order to perform the above-described detection of the perforation line P at the point where the optical unit 3 is disposed. For this purpose, the processing unit 4 has an output 41 connected to the input of the controller 300, and the controller is thus driven by the processing unit 4. The output 32 of the optical unit 3 is connected to each input 42 of the processing unit 4, and the processing unit thus receives the image acquired by the optical unit 3. The output of the controller 300 is connected to the input 31 of the optical unit 3. In the block diagram of FIG. 7, the controller 300 is connected to the output 41 of the processing unit 4, and the processing program is indicated by the reference sign EP. This program can be stored in the internal memory section of the processing unit 4 or can also be stored in an external unit connected to the processing unit 4.

[0030] Preferably, the illuminator 30 is a pulse linear illuminator.

[0031] For performing an experimental test, an Omron STC-MBS 163 POE matrix camera with an Omron FH2050 controller having a shutter speed of 1 microsecond was used at a position 30 cm away from the web-like material N (made of white tissue paper for manufacturing rolls of toilet paper). The illuminator 30 used for performing the experimental test was a Genesi GEVX 34-6K-UD-200-M12S illuminator. When the image was acquired, the web-like material N passed over a black support roller.

[0032] Among the paths followed by the web-like material N, at the locations where the web-like material N is stretched (for example, as described above, the locations where the web-like material follows the convex contour), by performing the above-described optical detection, the aperture of the camera can be fully opened. As a result, even with a short exposure time, more light can be made to enter the camera. Further, as the web-like material stretches, the visibility of the base surface is improved, and thereby the visibility of the perforations F is also improved.

[0033] Needless to say, by disposing a surface of a color different from that of the web-like material N behind the material itself, more accurate optical detection of the perforations F on each perforation line P is promoted.

[0034] A particularly advantageous solution from an economic point of view consists in providing an optical unit that can delimit a part of the width of the web-like material (for example, one third), that is, a part of each perforation line P (for example, one third), and attaching the optical unit to a carriage CM that can move orthogonally to the direction MD in which the web-like material N travels in the control zone ZC. The carriage CM can be attached to respective guides GC in a direction orthogonal to the direction MD in the control zone ZC. The carriage CM can be actuated by respective actuators AC that are controlled by the processing unit 4 appropriately connected to this actuator. Referring to the schematic diagrams of FIGS. 10A to 10C, the carriage CM arranges the optical unit 3 at control positions C1, C2, C3, that is, corresponding to the lateral portions C1, C2 and the central portion C3 of the path followed by the web-like material N. In this way, the optical unit can delimit the lateral portions and the central portion of each perforation line. In the schematic diagrams of FIGS. 9A to 9D, assuming that six blades 10A to 10F are attached to the blade holding roller 1 and each perforation line P1 to P6 is formed by the interaction between each blade 10A to 10F and the counter blade 20, the perforation lines are indicated by the signs P1, P2, P3, P4, P5, P6.

[0035] However, it is understood that the control positions may be different numbers (for example, two or four or five numbers) according to the width of the web-like material and the imaging range CR of the optical unit 3. In a possible control cycle according to the present invention, first, the carriage CM is positioned at the control point C1, and at six different instants t1 to t6, the optical unit 3 driven by the processing unit 4 acquires images of corresponding side portions of each perforation line P1 to P6 while the web-like material N moves along the direction MD. This process can be repeated a predetermined number of times (for example, 10 times), as a result, not because there are no perforations, but to reduce the risk of an error signal being issued, for example, due to temporary dust existing at the control point C1. At the lateral control point C1, if the images acquired by the optical unit reveal that not all perforations always exist on all perforation lines P1 to P6, the processing unit 4 issues an error signal. This error signal can be used to initiate a warning procedure for the operator assigned to the machine and / or an automatic correction procedure consisting of adjusting the inclination of the roller 2 or moving the roller 2 parallel to itself towards the roller 1, acting on each movable support 22 to restore the correct operation of the perforating device.

[0036] If the error persists even after the correction procedure is initiated, assuming that the counter blade is damaged or excessively worn, the operator stops the machine and manually intervenes in the perforating device. On the other hand, if no error signal is issued from the processing unit 4, the carriage CM is moved to the control point C2 on the opposite side, and the aforementioned procedure is repeated. Finally, the carriage CM is moved to the central control point C3, and the aforementioned procedure is repeated. In each of the above-described procedures, for example, even if the optical unit 3 detects the absence of perforations in a predetermined portion on the perforation lines P1 to P6 at the control point, an error signal may be issued by the processing unit 4.

[0037] In this way, the quality control of the perforations is divided into bands of web-shaped material having a preset width.

[0038] In the exemplary schematic diagrams of FIGS. 10A, 10B, and 10C, the perforation line indicates that there are no perforations in the right band (FIG. 10A), left band (FIG. 10B), and central band (FIG. 10C) of the web-shaped material N.

[0039] Preferably, the optical unit 3 first acquires an image of the perforation line at the lateral control points C1, C2, and then acquires an image of the perforation line at the central control point C3. This is because it has been empirically found that the disappearance of perforations occurs more frequently in the lateral bands of the web-shaped material.

[0040] However, it is also possible to use an optical unit 3 whose imaging range covers the entire control zone ZC. In this case, since the optical unit 3 can provide a clear image of a wider area, it is necessary to be equipped with more expensive optical components and electronic components, and such a solution may be more costly.

[0041] If the defects detected by the optical unit 3 are always related to the same perforation line (e.g., perforation line P4), the error signal can be used to control the automatic adjustment of the perforating device, for example, by moving the support 22 to bring the roller 2 closer to the roller 1. If the error persists, it can be considered that the corresponding blade 10D is damaged, and in this case, it can be replaced.

[0042] It is understood that the specific procedures for generating the error signal and / or the specific automatic correction procedures activated by the transmission of the error signal are different from those described above as examples. Generally, in practice, both the total number of missing perforations on the same perforation line and the number of consecutive missing perforations on the same perforation line can be predefined according to the quality established in advance for the finished product.

[0043] For example, the web-like material N can be a paper web formed by one or more superimposed plies, or a film of a plastic or bioplastic material, or a non-woven fabric.

[0044] From the foregoing description, it is clear that the punching device according to the present invention includes the following configuration. The punching device includes at least one of blades 10A to 10F configured to form a plurality of punching lines P in a web-like material N traveling along a predetermined path and a counter blade 20. These punching lines are each formed by a predetermined number of punches F arranged at intervals from each other by a predetermined value and aligned along a predetermined punching line direction CD. Further, the punching device includes an optical unit 3 adapted to optically detect the punches F of each punching line P in a control zone ZC arranged along the path downstream of the punching device GP while the web-like material N moves along this path. The optical unit 3 is configured to acquire an image of the web-like material N corresponding to the punching line P. The optical unit 3 is connected to a programmable processing unit 4 that receives an electrical signal generated by the optical unit 3 and processes them according to a programmed processing criterion including a comparison between the predetermined number of punches F of the punching line P and the number of punches detected by the optical unit 3 on each punching line. Based on the comparison thus made, the processing unit 4 can issue an error signal indicating an abnormal state regarding the operation of the punching device GP.

[0045] Therefore, according to the present invention, a comparison is made based on the detection of the number of punches of each punching line using the optical unit 3 for detecting the punches of each punching line and the processing unit for making the comparison.

[0046] In practice, the details of the implementation can vary in any case in an equivalent manner with respect to the individual elements described and illustrated, without abandoning the idea of the adopted solution and thus remaining within the scope of protection conferred on this patent according to the following claims.

Claims

1. A punching device (GP) comprising a counter blade (20) configured to form a punching line (P) on a web-like material (N) traveling along a predetermined path, and at least one blade (10A - 10F), wherein the punching lines are each formed by a predetermined number of punches (F) arranged at a predetermined interval and aligned along a predetermined punching direction (CD), an optical unit (3) is provided which is configured to optically detect the punches (F) of each punching line (P) in a control zone (ZC) arranged along the path downstream of the punching device (GP) while the web-like material (N) moves along the path, the optical unit (3) is configured to acquire an image of the web-like material (N) corresponding to the punching line (P), the optical unit (3) is connected to a programmable processing unit (4), and the processing unit (4) receives the electrical signals generated by the optical unit (3) and processes them according to a programmed processing criterion including a comparison between the number of punches detected by the optical unit (3) on each punching line and the predetermined number of punches (F) of the punching line (P), the punching device, wherein according to the comparison thus made, the processing unit (4) emits an error signal indicating an abnormal state regarding the operation of the punching device (GP).

2. The punching device according to claim 1, wherein the processing unit (4) is programmed to emit the error signal when the total number of punches (F) detected by the optical unit (3) on one or more punching lines (P) within the control zone (ZC) is less than a predetermined percentage of the predetermined number of punches.

3. The punching device according to claim 1, wherein the processing unit (4) is programmed to emit the error signal when the number of consecutive punches (F) detected by the optical unit (3) on one or more punching lines (P) within the control zone (ZC) is less than a predetermined value.

4. The control zone (ZC) is divided into a plurality of control sub-zones (C1, C2, C3) aligned transversely to the moving direction (MD) of the web-like material (N) in the control zone. The punching device according to any one of claims 1 to 3, wherein the optical unit (3) is periodically moved between the control subzones (C1, C2, C3) by respective handling units (CM, AC).

5. The control subzones include two lateral control subzones (C1, C2), The punching device according to claim 4, wherein the handling units (CM, AC) first arrange the optical unit (3) corresponding to the lateral control subzones (C1, C2), and then arrange it corresponding to a further control subzone included between the lateral control subzones (C1, C2).

6. The punching device according to any one of claims 1 to 5, wherein the processing unit (4) controls the operation of the optical unit (3).

7. The punching device according to any one of claims 1 to 6, wherein the path includes a convex surface on which the control zone (ZC) is arranged.

8. The at least one blade (10A to 10F) and the counter blade (20) are each attached to a respective support whose relative position is adjustable, The punching device according to any one of claims 1 to 7, wherein the error signal controls the relative positioning of the supports.

9. The punching device according to any one of claims 1 to 8, wherein an illuminator (30) operated by the processing unit (4) is associated with the optical unit (3).

10. The punching device according to any one of claims 1 to 9, wherein the processing unit (4) is programmed to issue the error signal when an abnormal state detected by the optical unit (3) occurs a preset number of times.

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