Patent Grant
8574383
1. Technical Field
The present invention relates to a corrugator or corrugating machine and a method of operating the machine for making corrugated paperboard. More particularly, the present invention relates to a corrugator having a separation sensor which is used to sense separation of layers of the paperboard which have been glued together.
2. Background Information
Corrugators for making corrugated paperboard are well known, and are sometimes referred to as corrugating machines or corrugating lines which include a series of linked machines. Corrugated paperboard or corrugated board has a number of common uses, including the formation of corrugated boxes, mainly used for shipping and storage. Corrugated paperboard is typically made from rolls of liner or paperboard which are typically large rolls of wound paper which may stretch out over several miles when unwound. Corrugated paperboard is formed of wavy or fluted paper known as a corrugating or corrugated medium which is glued to a flat sheet typically called a liner. Corrugated board can thus be made up of one or more layers of the corrugated medium and one or more of the liners. For instance, a single liner glued to corrugated medium creates a singleface corrugated board. Corrugated medium glued between two flat liners forms a single wall corrugated board. The addition of another corrugated medium and third flat liner to the single wall corrugated board creates a double wall corrugated board. Triple wall corrugated boards may also be formed with three layers of corrugated medium and four flat liners glued to one another in a similar alternating configuration.
Corrugators operate such that the paperboard, liners or webs unwind rapidly off of wound rolls and move downstream typically at a rate of 500 lineal feet per minute or more. This rate is often up to or in excess of 1,000 feet per minute. During the formation process, one of the liners typically passes between two corrugating rolls which form the liner into the corrugated medium, which is subsequently glued to the other liner in order to form the singleface web noted above, which is a continuous sheet of flat paper with fluted paper or the corrugating medium glued to it. Before the liners reach the corrugating rolls and before being glued together, they are typically heated by heating rolls and exposed to steam applicators or showers. Glue is then typically applied to tips of the flutes of the corrugated medium in order to glue the corrugated medium to the flat liner to form the corrugated paperboard.
One of the problems that arises in the formation of the corrugated paperboard is the separation of the corrugated medium from the liner after it has been glued together. Such a separation can cause substantial problems at certain locations downstream of the gluing or joining of the liner and corrugated medium. Thus, it would be highly beneficial in order to ascertain the separation between the layers of paperboard relatively shortly downstream of the gluing station in order to prevent these problems further downstream. The present invention achieves this goal.
The present invention provides a method comprising the steps of gluing a corrugated medium to a liner as the medium and liner are moving downstream through a corrugator to form a corrugated paperboard; and sensing with a separation sensor a separation of the glued medium and liner from one another.
The present invention also provides a corrugator comprising a plurality of rotatable rolls adapted to guide downstream movement of a corrugated medium and a liner; a glue applicator adapted to glue the medium to the liner as the medium and liner are moving downstream to form a corrugated paperboard; and a separation sensor which is downstream of the glue applicator and adapted to sense a separation of the medium from the liner.
The present invention further provides a combination comprising a corrugated paperboard comprising a corrugated medium glued to a liner; a paperboard conveyor system which during operation conveys the corrugated paperboard in a downstream direction; and a separation sensor positioned to sense a separation of the medium from the liner during downstream movement of the corrugated paperboard.
A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims.
Similar numbers refer to similar parts throughout the drawings.
The corrugator of the present invention is shown generally at 10 in
Corrugator 10 includes a paperboard conveyor system which includes a number of rotatable rolls which are rotatably mounted on the frame and on which the liners 14 and 16 and paperboard 12 are movably mounted or threaded primarily for downstream movement. These rotatable rolls include guide or tension rolls 24 around which the liners or webs 14 and 16 are threaded or partially wrapped such that the webs engage a cylindrical or circular outer perimeter of the various rolls as the webs move rapidly along the conveyor system during the formation process. Web 16 also engages and partially wraps around the outer perimeter of a first heating roll 26 which heats web 16 as it passes by and engages roll 26. A steam applicator or shower 27 is also disposed adjacent the path or pathway traveled by web 16 such that applicator 27 may apply steam to web 16 during its downstream movement and thereby alter its water or moisture content. The conveyor system further includes a pressure roll 28 which web 16 also engages and partially wraps around during travel along its pathway. Provided adjacent or along the path of web 14 are a second heating roll 30, a second steam applicator or shower 31, and first and second corrugating rolls 32 and 34. Like first heating roll 26, second heating roll 30 applies heat to web 14 as web 14 contacts and partially wraps around the cylindrical outer perimeter of roll 30 during its downstream travel. Steam applicator 31 is positioned to apply steam to web 14 to alter its water or moisture content. Corrugating rolls 32 and 34 are closely adjacent one another and include respective gear-like teeth so that when web 14 passes between corrugating rolls 32 and 34, said teeth of these rolls engage opposite sides of web 14 and press web 14 therebetween to form corrugated medium 36, which wraps around a portion of the outer perimeter of corrugating roll 34 prior to being glued to web 16.
Corrugator 10 further includes a gluing assembly with a glue applicator in the form of a glue applicator roll 38 which has an outer perimeter which is adjacent the outer perimeter of corrugating roll 34. A glue doctor roll 40 is positioned with its cylindrical outer perimeter closely adjacent the cylindrical outer perimeter of applicator roll 38. The lower portion of the outer perimeter of applicator roll 38 is in contact with and partially submersed in liquid adhesive or glue 42 which is contained within a glue pan 44. The above noted rolls rotate about respective parallel axes as indicated by the corresponding arrows shown in
Corrugated medium 36 includes multiple alternating ridges or flutes such that some of the flutes have flute tips 46 which are along one side of medium 36 and opposite side flute tips 48 which are along the opposite side of medium 36 and face away from the flute tips 46 which are adjacent a given set of flute tips 48. During the formation process, glue applicator roll 38 applies liquid glue to flute tips 48. Thus,
With primary reference to
Once paperboard 12 in the form of the singleface web is produced, it continues to move downstream (arrow C) toward a receiving section 54 of corrugator 10, which is thus downstream of pressure roll 28, corrugator roll 34 and the various other rolls and components previously noted. Receiving section 54 broadly represents various components of corrugator 10 which are used to further manipulate corrugated paperboard 12, either to finalize the production of paperboard 12 itself as an end product or to combine paperboard 12 with other layers such as additional liners and/or another corrugated medium in order to form the more complex corrugated paperboard structures discussed in the Background section of the present application.
In accordance with the invention, corrugator 10 includes a separation sensor assembly 56 which is configured to sense a separation of corrugated medium 36 and flat liner 16 after they have been glued together to form the corrugated paperboard 12. Assembly 56 is thus downstream of the various rolls 18-40 and steam showers 27 and 31, and also upstream of receiving section 54. Assembly 56 is in electrical or other communication with a control 58, which is also in electrical or other communication with the various driving components of corrugator 10 such that control 58 is capable of controlling operation of corrugator 10, which may include turning corrugator on and off in order to respectively operate corrugator 10 or shut it down to cease operations. More particularly, control 58 is in electrical or other communication with the various drive mechanisms or systems which put all of the moving components of corrugator 10 into operation such that webs 14 and 16 unwind respectively from rolls 18 and 20 and move through the conveyor system in order to be glued and thus joined together to form corrugated paperboard 12, and to keep paperboard 12 moving downstream along the conveyor system to the downstream end of corrugator 10. Control 58 is thus also capable of shutting down corrugator 10 or causing all of its pertinent components involved in the formation of paperboard 12 to cease operation. Control 58 typically controls the operation of the various drive systems of corrugator 10 in a manner to increase or decrease the rate of speed with which each component moves to increase or decrease the rate at which liners 14, 16 and paperboard 12 move downstream.
With reference to
With reference to
The operation of corrugator 10 is now described. When corrugator 10, which is typically electrically powered, is running, the conveyor system thereof drives the movement of webs 14 and 16 and the newly formed corrugated paperboard 12 in a downstream direction as previously discussed. More particularly, web 14 unwinds from the rotating wound roll 18 and is threaded around the various rolls 24, heat roll 30, and also around corrugating roll 34 whereby the corrugated medium 36 is newly formed as it passes between corrugating rolls 32 and 34. As previously discussed, heating roll 30 heats web 14 as it engages and moves past the outer perimeter of rotating heating roll 30. In addition, steam applicator 31 is typically operated to produced steam 87 in order to apply steam to web 14 as it moves past applicator 31 to increase the moisture content of web 14. Applicator roll 38 rotates with its outer perimeter engaging and picking up glue 42 from within pan 44 to transfer glue 42 to medium 36. The outer perimeter of doctor roll 40 limits the amount or thickness of glue extending radially outwardly from the outer perimeter of applicator roll 38. Applicator roll 38 rotates as the newly formed corrugated medium 36 revolves around corrugating roll 34 so that glue is transferred from roll 38 to medium 36 and more particularly is applied to tips 48 of the flutes to provide the glued fluted tips 48B immediately downstream of applicator roll 38.
Meanwhile, web 16 unwinds from the wound roll 20 and moves along the conveyor system threaded around the various rolls 24, heater roll 26 and pressure roll 28. As previously noted, heating roll 26 heats web 16 as it engages and passes around the outer perimeter of rotating heating roll 26. Steam shower 27 may also produce steam 87 which is applied to web 16. Web 16, along with corrugating medium 36 having glued tips 48B, passes between corrugating roll 34 and pressure roll 28, which rotates and presses on side 50 of web or liner 16 in order to force or press side 52 of liner 16 into engagement with the glued tips 48B whereby the corrugated medium 36 and liner 16 are glued to one another to form corrugated paperboard 12 (block 105 in
Throughout the operation of corrugator 10, sensor assembly 56 is operated whereby each sending unit 62 produces an ultrasonic sensing wave 88 (dashed lines) which is transmitted to receiving unit 64 through paperboard 12. As previously noted, separation sensors 60 are ultrasonic sensors which are capable of sensing the density of paperboard 12 as it is passing downstream between the corresponding units 62 and 64 within passage 70. Thus, sensor 60A senses the density of paperboard 12 generally adjacent side edge 84 while sensor 60B senses the density of paperboard 12 generally midway between edges 84 and 86, and sensor 60C senses the density of paperboard 12 generally adjacent side edge 86. Each of sensors 60 is thus continuously sending signals corresponding to the density of paperboard 12 at any given moment to control 58, which includes a computer or appropriate logic circuits to determine the density, compare it to a predetermined value or value range, and thus evaluate whether the given density is at the value or within the value range. If the determined density is within the value range, control 58 will continue to operate corrugator 10 to continue producing additional paperboard 12.
However, the measured density value is not always within the value range, which is the case illustrated by
Then, as illustrated at block 108 in
A worker will inspect the faulty section and typically various components of corrugator 10 and/or webs 14 and 16 to ascertain one or more problems which caused the separation of corrugating medium 36 from liner 16. Once the problem has been ascertained (block 109), the problem is fixed, or corrective action is taken to ensure the proper gluing of the medium and liner (block 110). Some of the problems and corrective actions are noted below.
The problem could be related to the paper, the glue or certain aspects of corrugator 10 itself. One of the problems may be that one or both of the rolls 18 or 20 do not have the proper water or moisture content, which is typically about 5% to 8%. Although moisture content of the paperboard in these rolls may be higher than desired, problems with proper gluing more often occur when the moisture content is too low. In the scenario where the paperboard is too moist, a corrective action may involve increasing the temperature of the corresponding heating roll 26 or 30 in order to increase the temperature of the corresponding web to help dry the paper out, reducing the rate at which the webs 14, 16 and paperboard 12 move downstream to provide greater duration of contact with the heating rolls, or reducing the rate at which steam 87 is applied from one of showers 27 or 31 or even stopping steam application if steam is being used. On the other hand, if the moisture content of the paperboard is too low (too dry), the most common solution would be to increase the rate of steam 87 being applied to one or both of webs 14 and 16 although the temperature of the heating rolls may also be reduced and the rate of travel of the webs and paperboard may be increased as well. If the paperboard on one of rolls 18 and 20 does not have the proper moisture content and cannot be fixed by the above-noted procedures, the corresponding roll may have to be removed and replaced as indicated at arrows G in
In addition to the moisture content needing to be within a certain range, the webs 14 and 16 should be at a suitable temperature to facilitate the proper formation of corrugated medium 36 and the gluing of medium 36 and liner 16 to one another. Controlling the temperature of webs 14 and 16 is primarily related to the use of heating rolls 26 and 30 although the use of steam showers 27 and 31 also has an effect on the temperature of the webs. Thus, if the webs are not within a suitable temperature range, the temperature of heating rolls 26 and 30 may be increased or decreased to respectively increase or decrease the temperature of webs 16 and 14 as a result of contact with the heating rolls. As also noted above, the rate at which webs 14 and 16 move downstream and thus are in contact with heating rolls 26 and 30 corresponds to the temperature of webs 14 and 16 downstream of heating rolls 26 and 30. Thus, the rate of downstream movement of the webs may also be increased or decreased to adjust the temperature of the webs. In addition, the rate at which heating rolls 26 and 30 are rotated may contribute to the problem of properly heating the webs 16 and 14, especially if the gearbox and/or motor driving the given heating roll has become defective to the degree that the heating roll is no longer being driven by the motor and/or gearbox, but only driven by the movement of the corresponding web 14 or 16 along the outer perimeter of the given heating roll. Thus, the rate of rotation of the heating rolls may need to be adjusted, or the gearbox and/or drive motor associated with the given heating roll may need to be adjusted or repaired if broken. As noted above, steam showers 27 and 31 may be controlled to not only adjust the moisture content of webs 14 and 16 but also to adjust the temperature thereof, with an increase in the amount or rate of steam being associated with increasing the temperature of the webs and a decrease being associated with reducing the temperature of the webs.
As noted above, one of the problems which may arise with the proper gluing of the layers forming the corrugated paperboard 12 involves the glue 42 itself. The proper formulation and particularly the viscosity of glue 42 is typically held within a certain range in order to ensure that the proper amount of glue with the proper characteristics is applied to liner 36. With modern corrugators, the viscosity and formulation of the glue is typically well controlled and usually does not present a problem. For instance, corrugators are often set to test the viscosity of the glue every 10 minutes or so in order to ensure it is within the proper range. Furthermore, corrugators are typically automated to produce new batches of glue at regular and relatively short intervals, for instance every two hours although this may vary.
Application of an improper amount of glue between the medium and liner is a fairly common problem which may cause the separation of the medium and liner. The two primary dimensions at issue with application of a proper amount of glue are the thickness of the glue and the axial width of the glue. The thickness of the glue is the distance which glue 42 extends outwardly from tips 48B after applied thereto by applicator roll 38. The axial width of the glue applied is that previously discussed with respect to
In addition, the thickness of glue applied to tips 48 is controlled by the use of doctor roll 40 or another doctor device such as a non-rolling doctor blade, which is adjacent applicator roll 38. Roll 38 typically picks up excess glue 42 as roll 38 passes through the glue 42 within pan 44. The doctor device controls and in particular limits the amount and thickness of glue 42 which passes between the doctor device and roll 38 and remains on the outer perimeter of applicator roll 38 as the outer perimeter of roll 38 rotates past the doctor device such as doctor roll 40. Thus, the distance between the doctor device and the applicator roll 38 may be used to adjust the thickness of glue 42 which is transferred to tips 48. More particularly, doctor roll 40 may be moved closer to and further away from doctor roll 38, as respectively indicated at arrows K and L in
As previously noted, the axial width of the glue 42 which is applied to medium 36 may also be one of the problems which causes separation of the medium and liner. For example,
Another reason that an incorrect amount of glue may be applied between the medium and liner is related to the rate at which webs 14 and 16 and paperboard 12 move downstream. A downstream movement rate which is too high may cause the application of the glue to be too thin or insufficient whereby a separation is created. A problem could also be caused by this rate being too slow. Thus, a change in this rate may fix the problem of improper gluing. Reducing the downstream rate of the webs and corrugated paperboard if too high may allow sufficient glue to be transferred from applicator roll 38 to corrugated medium 36. Increasing this downstream rate if too low may also fix the problem.
Regardless of what the problem is, once it is fixed, the corrugator may be operated again to restart formation of the corrugated paperboard (block 111 in FIG. 7). More particularly, the downstream movement of the remaining portions of paperboard is restarted to begin forming additional corrugated paperboard 12 from webs 14 and 16. Thus, the downstream remaining portion 12A shown in
The present invention thus provides a separation sensor assembly which may be used with a corrugator in order to determine when separation of corrugating medium from a liner occurs. The ability to assess this separation thus allows the faulty segment of paperboard to be removed in order to prevent subsequent problems which would otherwise occur if the faulty segment continued downstream travel through the corrugator. The present invention thus prevents damage and substantially time consuming repairs which might occur if such a faulty segment were to move downstream into certain sections of the corrugator.
In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.
Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.
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| Number | Date | Country | |
|---|---|---|---|
| 20120118474 A1 | May 2012 | US |
