Patent Application
20110245056
This invention relates generally to the application of a window film over a die cut opening in a folding carton, and is particularly directed to the formation of rigid windows from rolls of rigid window materials and the application of the thus formed rigid windows to folding cartons in a single, high speed operation.
Window film is often applied over a die cut opening in a folding carton to provide a way to view the contents inside the carton. The window may be within the perimeter of one or more panels of the carton.
Windows in more than one panel of a carton are often referred to as panoramic windows, particularly if the window continuously extends from one panel, across the score or crease line at a corner of the carton, and into an adjacent panel.
In larger cartons, or in cartons containing more expensive or attractive contents, a substantially thicker window, approximately 0.007″ or thicker is used, as opposed to thinner films of approx 0.0005″ to 0.003″ thick. Such thicker window materials are known as rigid windows because their thickness renders them relatively stiff or rigid. Rigid windows may be made of such polymers as polyester, calendared PVC, or polystyrene sold by Plastic Suppliers, Inc. of Columbus, Ohio, and others.
When a rigid window is used in conjunction with a panoramic window opening in a folding carton, the rigid window material will typically require a score essentially aligning with the score, or corner, of the carton. Further, the rigid window will typically require die cut reliefs, or notches, where the rigid window material would otherwise overlie the carton material's score or crease. The relieved areas of the rigid window permit the carton to more easily fold along the carton's score line. If the window material were not so relieved, the score in the carton and the score in the overlying window material would resist folding not unlike the binding that would occur if a door were hinged along two offset hinge axes. The scoring and relieving requirements have historically been provided by pre-die cutting the rigid window blanks with either rotary or platen die cutting equipment which cut the window blank from a roll or from a larger sheet, respectively. This defines the complete perimeter and scores of the window blank. The pre-cut window blanks are collected in a stack for subsequent application to folding cartons.
Rigid windows, as well as thinner window films, have been applied to folding carton blanks by windowing machines such as those manufactured by Heiber+Schröder Maschinenbau GmbH of Erkrath, Germany. The operation of supplying an adhesive pattern to bond the window material and affixing the window in the desired position, or registration, on the carton is often referred to as window patching. In the case of the traditional Heiber+Schröder Maschinenbau GmbH machine, the rigid windows are supplied to the machine as precut and pre-scored singulated blanks. An adhesive pattern is applied to the folding carton blank and the rigid window is fed onto a vacuum cylinder which carries the rigid window on the cylinder's circumference until the rigid window is transferred to the carton blank over the adhesive pattern on the carton blank and in the desired location on the carton blank. More recently, Heiber+Schröder Maschinenbau GmbH has offered an attachment for feeding rigid window material from a roll, hot creasing, and die cutting the window material and applying it to folding cartons. The die cutting is a punching operation, performed while the window material is stationary, using male and female dies. This has practical limitations on speed as it uses a reciprocating punching station with male and female dies. Male and female dies are more complex and costly than a rotary die cylinder and rotary die cylinders are easy to set up and operate. The carton blank, now equipped with a window, is conveyed to a stacker where the flat carton blanks are collected for subsequent processing on a separate machine, i.e., a carton folder/gluer. On occasion a Heiber+Schröder Maschinenbau GmbH windowing machine has been built into a carton folder/gluer so that windows may be applied to folding cartons and the cartons folded and glued into a ready-to-fill configuration in a single pass operation.
Since about 2000, Tamarack Products of Wauconda, Ill., USA has made the Vista® window applicator (with reference to U.S. Pat. No. 6,772,663) which is typically installed on a carton folder gluer to apply windows in conjunction with the carton folding and gluing process for a single-pass operation. The Tamarack window applicator may also be installed on an abbreviated conveyor to separate the windowing process from the folding gluing process. The Vista® window applicator senses the lead edge of a carton as it is transported on carrier belts and a triggering signal activates feeding, gluing, and cutting axes to provide a cut window patch with a pattern of adhesive and delivers it for application onto a carton blank in the desired position. The Vista® window applicator differs from most other window applicators in several aspects. For example, the adhesive pattern is applied to the window film rather than the carton blank. This has the advantage that the adhesive pattern is inherently covered by the window patch. In systems where the adhesive pattern is applied to the carton blank, when a window misfeeds, i.e., is not placed in the proper location on the carton, or is missing altogether, the adhesive transfers onto various conveying components, e.g., transport belts, rollers and folding swords, fouling them with adhesive that can cause misfeeding of the carton blanks and the need to clean conveying belts and rollers to restore proper function. In approximately 2003, a die cut unit was added to the Vista® applicator to provide die cuts, for example perforations, for ease in the formation of an opening for the removal of facial tissues through a polyethylene window in a folding carton. The die cut unit was servo driven and coordinated with the feeding, gluing and cutting axes of the Vista® applicator.
Until the instant invention, however, the Vista® window applicator has not been adapted to process rigid window materials.
The instant invention relates to a new method and apparatus for providing rigid windows on cartons wherein the rigid window material is supplied to the apparatus as a roll of rigid window material, rather than as pre-die cut, pre-scored singulated blanks.
The instant invention also relates to a process that eliminates two off-line processing operations currently practiced in the prior art. Namely, the instant invention draws from a roll of rigid window material and die cuts, scores and singulates the blanks (previously a separate operation in the prior art); applies the singulated blanks onto folding cartons (normally a second separate operation in the prior art); and performs the folding and gluing operations (normally a third separate operation in the prior art), all in one pass, on a combined machine (instead of two or three separate machines as in the prior art). While the rigid window material is sometimes referred to as being “transparent” in the following description, the rigid window material may include printing or other graphic features and thus does not have to be entirely, or 100%, transparent as used with the present invention.
The instant invention enhances the operation of a combination of prior art machinery: a carton folder gluer and a Tamarack Vista® window applicator equipped with an optional die cut station. The present invention provides a new way of webbing the window material that utilizes a die cut station's anvil cylinder as a feeding cylinder. This new webbing approach also allows the die cut to operate at an essentially constant rate of rotation while accommodating the Vista® applicator's stop-and go operation.
A reconfigured die cylinder is used to cut notches and make fold scores (sometimes the scoring is done at an additional station in conjunction with die cutting).
A waste removal system follows the die cutting operation to remove the notch material
The inventive process further provides instant feedback as to the alignment of the window fold scores with the carton fold scores. In other words, if the window scores do not align with the carton scores, the carton folding process will be impeded, possibly interrupted. This immediate indication of misalignment then allows prompt corrections to be made, with minimal waste of window and carton materials. In comparison, the prior art processes are separated and so a large batch of windowed cartons may be faulty. While the alignment problem will be evident in the subsequent, separate carton folding/gluing process as an interruption or failure, the entire batch of faulty windowed cartons would likely have to be scrapped.
Further, the inventive apparatus and process provides some degree of self-alignment, or at least self-centering, of the window fold scores with the carton fold scores—this by virtue of the fact that the adhesive does not immediately dry and so the window may ‘nest’ or shift in the carton folding/gluing process to a position that allows the folding/gluing process to continue without a “jam” or “jam-up,” as such interruptions are often referred to in the art.
The following features of the present invention provide improved performance in the application of rigid windows to a folding carton in terms of increased reliability, higher speeds, monitor-free operation, roll film compatibility, improved waste ejection and removal, reduced material costs, immediate positioning accuracy feedback and simplified design.
The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which:
The window patch material is supplied from a roll 113. Window material unwinds from roll 113 to provide a web 114 of window material. For the rigid windows of the instant invention, a relatively thick and stiff window material such as 7 mil (0.007″, 180 micron) polyester such as supplied by Plastic Suppliers of Columbus, Ohio or 8 mil polyester from Klöckner-Pentaplast of America Inc. of Gordonsville, Va. is supplied in roll 113 and unwinds to provide web 114 to an accumulator 115.
Webs 114 and 114a shown in
A rotary die cutting station 116 including an anvil cylinder 107 and die cylinder 108 is driven by one servo motor (when the cylinders 107 and 108 are geared together) or by a servo motor driving each of the cylinders commanded by control unit 105. Die cutting station 116 is located upstream of the accumulator 115. This upstream position is advantageous for rotary die cutting because of the steadier speed of web 114. If the rotary die cut station 116 were located downstream of accumulator 115, the rapid accelerations and decelerations of both the web 114a and the die cutting cylinders 107 and 108 would have to perfectly match because the die cut cylinders engage the web for substantial portions, and in many cases 360° of rotation. Any inevitable speed mismatch could create slack in some portions of web 114a that would almost certainly cause lateral tracking problems, distort the web 114a, or cause deterioration (from scuffing, tearing or shearing) of the die cut pattern.
Web 114 may be wrapped around a significant portion of anvil cylinder 107 by routing the web via idler 119 or gripping the web 114 against the anvil cylinder 107 with a gripper roller or gripper wheels (not shown) as is known in the art. This allows the anvil cylinder 107 to also act as a feed roller and better assure that the speed of the web 114 more closely matches the speed of the die cutting cylinders 107 and 108.
The notch 201 is die cut with the die cut cylinders 107, 108 and the material within the notch is removed from web 114 in known ways, e.g., by gravity, routing the web through a turn, and/or air jets impinging on the web. The removed material may be collected by a chute 117 which is connected to a removal system (not shown) that conveys waste material away via air flow in a hose or pipe. Notch 201 permits easier folding of carton 102 by reducing shear forces at the fold. The timing or location of notch 201 relative to cut line 203 is adjusted and maintained by control unit 105. An optical scanner 120 provides a timing signal when an edge of notch 201 is detected. The timing signal from scanner 120 is transmitted to control unit 105. In the embodiment in
The score, or perforation, 202 may also be applied by die cutting cylinders 107, 108. Alternatively, the score 202 may be applied at a separate scoring station 118. Scoring station 118 may consist of a scoring wheel or wheels and a separate anvil cylinder, or the scoring wheel, or wheels, may act against die cut anvil cylinder 107, which is not shown in
A scoring station 118 separate from die cutting station 116 also provides another embodiment of the invention, wherein the die cylinder 108 may accommodate repeats other than its circumferential dimension. This is accomplished by rotating die cylinder 108 at a continuous but varying rate, a technique known in the art as profiling or camming. For example, if the die cylinder 108 has a circumference of 10″ and the die pattern for the notches is not in 360° rotational contact with the web 114, the die cylinder may be sped up between the notches to deliver a pattern of notches shorter than the 10″ circumference of the cylinder 108. In this embodiment, and where the die cutting and anvil cylinders 108, 107 are geared together to permit driving with a single servo axis, the web 114 would not be wrapped around the circumference of anvil cylinder 107 and web 114 would be free to slip on anvil cylinder 107 during the rotational increase in speed.
The web of window material 114 is supplied from either roll 404 or 405. Splicing head 406 allows a new roll to be spliced to an expiring roll without stopping web 114 (known as a flying splice). Accumulator 403 modulates tension in film web 114 by controlling the spindle brakes for rolls 404 and 405. Accumulator 403 also accommodates brief tension variations that may occur during a splice so the web 114 may be supplied out of accumulator 403 at a relatively constant, continuous speed. Pull roller 407 is servo driven and commanded by control 105 to drive web 114 at a relatively continuous rate that is essentially the average speed of the stop-and-go web 114a in the Vista® window applicator. Accumulator 412 isolates the varying or even stop-and-go consumption of web 114a as it is consumed by the Vista® window applicating machine (see 100 in
Splicing system 401 may be used in various positions relative to the Vista® applicator, for example, on the front or rear side of the Vista®, and parallel or perpendicular to the Vista®. One or more turn bars, such as the turn bar assembly 408, may be located between the Vista® and the splicing system 401 to maneuver the web 114 through the required 90° turns as is known in the art. The drag of the turn bars may serve to undesirably add tension to the web, however control system 105 may be used to advantageously adjust the speeds of feed rollers 106 and 407 so that tension remains desirably low and nearly constant through any such turn bars. This reduces scratching of the window material and reduces variation in lateral tracking of the web 114.
A scanner 409 is used to detect the position of the die cut notches 201 and the scanner output is transmitted to control system 105 and processed to command adjustments for feed cylinder 106 rotation in relation to the cutter cylinder 111 to register the position of the notch 201 relative to the position of the cut line 203.
As described previously herein, it may be advantageous to separate the diecutting and scoring operations by adding a scoring station 410.
A conventional web guide 411 is provided to control the lateral position of the web as it enters the scoring and slitting station.
Web 114 is routed through the die cut station 116 where die cylinder 108 has a raised cutting edge shaped to define notch 201 of
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications that fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.
