Device and method for splicing

Abstract

The present disclosure relates to a method for splicing a web of packaging material, comprising: guiding the web of packaging material through a splicing device comprising one or more imaging devices, a slitter, and a sealing unit; acquiring a first set of images of one or more areas of the packaging material, storing the acquired first set of images, slitting the web of packaging material in one or more locations to form a tail end and a head end of a web of packaging material, aligning the head end and the tail end and superimpose one on the other in preparation for forming a splice, utilizing the imaging devices and the stored acquired first set of images to fine tune the alignment of the head end and the tail end, sealing the splice.

Claims

1. A method for splicing a web of packaging material, comprising: guiding the web of packaging material through a splicing device comprising one or more imaging devices, a slitter, and a sealing unit; acquiring a first set of images of one or more areas of the packaging material, storing the acquired first set of images, slitting the web of packaging material in one or more locations to form a tail end and a head end in the web of packaging material after the acquiring of the first set of images, aligning the head end and the tail end and superimposing one on the other in preparation for forming a splice, utilizing the one or more imaging devices to acquire additional images of the one or more areas of the packaging material after the superimposing of the head end and the tail end of the web of packaging material and the stored acquired first set of images to fine tune the alignment of the head end and the tail end, wherein all of the one or more imaging devices are used for the acquiring of the first set of images and the additional images, sealing the splice.

2. The method of claim 1, wherein the sealing is performed using a combination of heat and pressure during a predefined period of time.

3. The method of claim 1, wherein the one or more imaging devices consists of a single imaging device.

4. The method of claim 1, wherein the first set of images is acquired from an unaltered portion of the web of packaging material before any splicing of the web of packaging material.

5. The method of claim 1, wherein the first set of images is stored in a memory for use on a subsequent web of packaging material.

6. The method of claim 1, wherein the additional images of the one or more areas of the packaging material are compared to the stored acquired first set of images to fine tune the alignment of the head end and the tail end, the fine tuning being complete when the additional images and the stored acquired first set of images are identical.

7. The method of claim 1, wherein the one or more imaging devices are each fixed in the splicing device so that the web of packaging material is guided relative to the fixed one or more imaging devices, and the method further comprises moving the head end and the tail end of the web of packaging material after the slitting of the web of packaging material by a fixed distance so that the additional images are taken at a same location of the web of packaging material as the first set of images.

8. The method of claim 1, wherein the one or more imaging devices consist of four imaging devices, and two of the four imaging devices are positioned upstream of the one or more locations where the slitting occurs, the other two of the four imaging devices are positioned downstream of the one or more locations where the slitting occurs, and all of the four imaging devices collectively are used to acquire both the first set of images and the additional images.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a very schematic side view of a rudimentary system for processing a web of packaging material

(2) FIG. 2 is the first view in a sequence of three showing splicing of a first web of packaging material to a second web of packaging material.

(3) FIG. 3 is the second view in a sequence of three showing splicing of a first web of packaging material to a second web of packaging material.

(4) FIG. 4 is the third view in a sequence of three showing splicing of a first web of packaging material to a second web of packaging material.

(5) FIGS. 5 and 6 illustrate a sequence starting with a position corresponding to the one shown in FIG. 4, yet with some more detail.

(6) FIGS. 7-9 illustrate yet another sequence similar to that of FIGS. 2-4 yet from above.

DETAILED DESCRIPTION

(7) FIG. 1 illustrates in ultimate simplicity the setup of the present disclosure. What is shown is a web 102 of packaging material being wound from a first reel 104 to a second reel 106. Between the first and the second reel the web 102 passes over and under a number of rollers and guides not necessary to be described in detail in the context of the present invention and merely illustrated by the hatched rectangular area 108. Furthermore, at least one slitter and a sealer comprising a pressing device with a heater and an anvil are arranged along the path of the packaging material web. The latter components are not shown in FIG. 1, yet they will be shown in the description of further drawings.

(8) One sequence according to the present disclosure will be described referring to FIGS. 2-4. In FIG. 1 the general setup is shown. The first reel is not shown since FIG. 2 illustrates a situation where the winding from the second reel to the first reel 106 is about to end. A tail 103, i.e. the trailing free end, of the first web 102 of packaging material is shown. A number of imaging devices 110, 112, 114, 116 are arranged such that they may monitor various portion of the packaging material. In the present arrangement the cameras 110 and 112 are arranged to monitor different portion of one lateral edge of the packaging material web, while cameras 114 and 116 are arranged to monitor distinguishable areas in the main body of the packaging material web. Distinguishable areas may correspond to a register mark or merely a particular area of the d?cor. There are many kinds of imaging devices commercially available and for simplicity they will be referred to as cameras in the following. Any type of digital or analogue imaging devices suitable for the purpose may be used. Returning to FIG. 2, the tail end 103 of the first web is located, and an area corresponding to an area to be spliced is imaged using one or more cameras. So far the area is not affected by any splicing and in the present embodiment the cameras 110 and 112 acquires images of the edge portions while the cameras 114 and 116 register two other areas of the unaffected web. These images will be used as a template for the splicing operation to come, but first the first web is moved to a slitter where it is cut in an appropriate way, e.g. in the way suggested in the patent document referred to previously. Following the slitting or cutting a head end 121 of the second web 120 is cut or slitted in a similar manner. A general rule is that the first web and the second web are cut in the same angle in relation to a transversal direction of the webs, so as to obtain a symmetric splice, another reason being that the same slitter is used for the operation. The angle in a thickness directionthe undercut, however, does not necessarily have to be the same, and the undercut as well as the effects thereof will be explained in closer detail referring to FIGS. 5 and 6.

(9) For localization of the correct slitting position use may be made of a fifth camera 118, yet other means are possible and since it is not the main theme of the present application these other means will not be discussed in detail. The camera 118 may monitor the position of a register mark, and by moving the web so as to maintain the register mark in a correct area in relation to the camera a correct slitting position may be localized. In the field of printing a register mark may have a specific meaning, yet for the purposes the present embodiment any defined area of the d?cor of the packaging material may be used. The exact position of the slit is not critical since the d?cor of the packaging material web is not continuous but arranged in increments of a single packaging container.

(10) After having been cut or slitted the tail 103 is moved to a splicing area, by moving the web 102 a fixed distance controlled by a control unit of the splicing device. In a next step, not shown, a new reel 104 may be arranged, and a second web 120 of packaging material may be thread through the rollers of the splicing device. The leading end 121 of the second web is cut at a suitable location, ensuring an overlap. As described above a suitable position may be found using the imaging system, or alternatively the slitter may have a sensor system detecting crease lines or register marks of the web by other means. Example includes optical marks and magnetic marks, etc., as well as defined areas of the d?cor. Irrespective of the sensor system used the head is cut at the same angle in the transversal direction of the web, yet preferably with an undercut for reasons to be explained.

(11) For the purposes of the present disclosure the second web 120 may as well correspond to the first web, i.e. in a situation where a section of the web has been removed there is only one web being spliced. For the actual splicing operation this is not material.

(12) Following the slitting the head 121 of the second web is moved to the splicing area by being moved a fixed distance, and the tail 103 is superimposed onto the head 121. Based on controlling the movement of the web 102 and 120 the splice may be localized with a tolerance in the order of a couple of millimeters. Subsequently the position of the tail 103 and the head 121 is fine tuned by input from the at least one camera. The image of the unscaved web is compared to the monitored image of the corresponding area of the splice. The tail and the head respectively are clamped to a positioning device and then their relative position is altered until the position is in agreement with the previously acquired image of the unscaved area.

(13) For the present, embodiment the tail 103 and head 121 is moved until all cameras 110, 112, 114 and 116 acquires images identical to the once previously acquired. At that time the head and the tail are bonded to each other and the splicing operation is finalized. In any downstream operation the splice will now not affect the operations. Still, once a packaging container comprising the splice has been manufactured it is standard operation to waste that packaging container, at least when it contains a liquid product.

(14) The actual imaging may be done in numerous different ways and in the following some suggestions are given.

(15) In first example there is one camera for the head and one camera for the tail respectively. Each camera is arranged to image a particular section of the packaging material web. The particular section may be a register mark, or it may be a particular portion of the d?cor. One effect of using a particular portion of the d?cor is that the method becomes very versatile. As long as the particular portion is distinguishable the method may be used. Before splicing is commenced each camera acquires an image each. These images will act as the target; once the splice is arranged such that the images are identical, the splice will not affect downstream operations. After the initial images are acquired the method proceeds according to what has been already described.

(16) In a second example the two cameras are not imaging a particular portion of the web, they merely acquires an image each. A condition for the imaged areas is that one camera should provide a view of an area that will be present on the tail, and the other should provide a view of an area present on the head, in a splicing position that is. The method then proceeds according to what has been already described.

(17) In a third example a single camera is used, and this camera acquires an image of an area that will be present on both the head and the tail; i.e. the area imaged of the unscaved web will include the splice once the splicing is performed. This example will comprise some more elaborate image processing and recognition, yet as such that image recognition may be a straightforward operation.

(18) In a fourth example one or more cameras are arranged for monitoring a position of a lateral edge of the web. Several downstream operations may be based on the assumption that at least one of the lateral edges of the web is considered as having zero tolerance. For this reason it may be beneficial to monitor the position of that lateral edge. The monitoring may be performed by acquiring images in the same way as has already been described, implying that there will be two cameras for the head of the web and two cameras of the tail of the web. Apart from ensuring correct positioning of one of the lateral edges there is an additional advantage in utilizing four points instead of two when aligning the head and the tail respectively. This corresponds to the example as described referring to FIGS. 2-4.

(19) Unless technically impossible, the examples given may be combined for further or similar effect.

(20) Following the fine tuning the tail and the head are bonded to each other using the sealing device indicated by an anvil 122 and a sealing bar 124 in FIG. 4. In the sealing device pressure to the splicing area and at the same time it is heated. The sealing is performed for a predetermined period of time. This bonds the first web to the second web, the second web to the first web, or both, thus finalizing the splicing sequence. As mentioned previously the above splicing sequence may be performed for the reason of removing a section of a single web or to add a second web to a first web, irrespective of which the process will be similar.

(21) Some more details of the sealing, or bonding, are shown in FIGS. 5 and 6. In FIG. 5 it is shown in a detailed view how the tail of the first web has been superimposed onto the head of the second web. A simplified packaging laminate is shown in order to elucidate the use of an undercut head and tail. The packaging laminate has a carton or fibrous core 129 and 133 respectively, which may be prone to absorb moisture, having a detrimental effect on the properties of the packaging laminate. To protect the carton core and to provide other barrier properties it is sandwiched between two layers of plastic 128, 130 and 132,134 respectively. Further layers may be applied, usually to accomplish some barrier properties against liquids, particular gases, and light. The number of recipes used for packaging laminate are vast and evolving and it is not the purpose of the present invention to pick a selected number of laminates, nor should the present invention be limited in view of only laminates mentioned since the present disclosure relates to a method and device for splicing.

(22) The view of FIG. 5 illustrates the situation prior to bonding, and the view of FIG. 6 illustrates the situation after bonding. After bonding the pressure and temperature have bonded the first web to the second web where the plastic layer of the first web is in contact with the plastic of the second web. Furthermore, due to the undercut edge the plastic layer on the remote side (remote to the other web) of each web has been bonded to the other web. In this way the carton core is fully protected after sealing.

(23) A sealing anvil 122 is arranged on the side of the first web and a heated sealing bar 124 is arranged on the opposite side, the side of the undercut second web.

(24) Temperature and pressure is applied for a predetermined period of time, and as the sealing bar is retracted in relation to the anvil the result as shown in FIG. 6 appears. In an embodiment where the heated bar 124 is arranged on what is to be a side facing inwards in a packaging containeronce formedan effect may be that the performance of the sealed undercut end may be optimized such that an optimum pressure, temperature and time is used when bonding the first web and the second web.

(25) To further describe the present disclosure some plan views are shown, still very schematic. The sequence of FIGS. 7-9 will be explained in the following. The purpose of the illustration is to exemplify how the method enables splicing with adequate tolerances. The web is shown as seen from above, and the hatched areas correspond to areas where creasing patterns for top and bottom of the packaging container are arranged. In these areas there are a lot of crease lines and therefore they are not will suited for splicing operation, though it would by no means be impossible to accomplish a splicing operation in such an area. Between the top creasing pattern and the bottom creasing pattern the creasing pattern for forming the body of the packaging container is situated. This creasing pattern mainly consists of creasing lines extending between the top creasing pattern and the bottom creasing pattern, and there are not as many creasing lines per surface area and the when formed the resulting container will not be folded in as many locations. This makes the creasing patterns dedicated for the body of the container more suitable for a splicing operation.

(26) In FIGS. 7-9 the cameras are not shown, though to facilitate understanding of the already described embodiments areas corresponding to areas imaged by the cameras shown in FIGS. 2-4 have been referred to using the same reference numbers with the addition of a prim sign, i.e. an exemplifying view of camera 110 is designated 110 etc.

(27) In FIG. 7 a web 102 prior to splicing is shown. In the particular example it is a single web, and the scenario is that a segment of the web is to be removed due to a defect, i.e. a so called doctoring process. In the first step imaging of the areas 110, 112, 114 and 116 is performed. As has been mentioned before this is performed before the web is slit. The inclined lines 103 and 121 are meant to indicate the tail and the head respectively, showing how the web is slit to form an overlap. First the tail 103 is cut/slit downstream the defect segment, and thereafter the head is cut upstream the defect segment of the web, or vice versa. At least one top/bottom pattern is removed in the doctoring process since the head and the tail cannot be cut in the same body pattern due to the overlap. Considering the view of FIG. 8 it is self-explanatory that the situation at this point forward is the same for a doctoring process where one single web is mended as for a situation where a second web is spliced to a first web. Therefore the present disclosure should not be limited to a particular reason for performing the splice, but to the splicing method as such.

(28) In the view of FIG. 9 the head and the tail have been superimposed and the cameras are again activated to ensure that the positioning is correct before the two ends are attached to each other. The disclosed method, according to any of the embodiments thereof is highly accommodating to the design (or d?cor) of the web of packaging material. Any acceptable flaw in the design will be imaged in the first step and accounted for automatically in the splicing operation.

(29) In one or more alternative embodiments, not disclosed in detail a first set of images acquired are acquired from a memory rather than from the actual web to be processed. Such an embodiment may require some more elaborate web handling but apart from that the method as such may be put into practice without any significant issues. Though the method is not as accommodating to the design of the web being processed, a beneficial effect may be that one step may be eliminated from the method as performed on an actual web of packaging material, which may save some time in the process.