Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1997-07-01
2001-03-27
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S470000, C156S494000, C156S495000, C034S637000, C034S454000
Reexamination Certificate
active
06206995
ABSTRACT:
TECHNICAL FIELD
This invention relates to moving-web assembly lines and, more particularly, to a moving-web slack reducing system including a deformable tension roller. Specifically, the slack reducing system may be applied in a preheater assembly for a machine for manufacturing corrugated board.
BACKGROUND OF THE INVENTION
Corrugated board can be manufactured in many different widths and thicknesses. The thickness of the board is determined by the number of medians and liners in the board. First, corrugations or flutes are created in a paper median by passing the median through a corrugator. Then, an alternating series of paper liners and paper medians, with an adhesive between each layer, are brought together in a moving web to form a board of desired thickness. The moving web passes through an assembly line that includes a hotplate section, where heat and pressure are applied to dry the adhesive, and a cooling section, where the board is cooled. The moving web is then cut and scored to make board of different shapes and sizes for boxes and other items.
Uneven moisture content in the source paper, which can cause portions of the board to shrink after the adhesive has set, is the principle cause of warping and the resulting waste encountered in manufacturing corrugated board. Accordingly, it is important to dry the source paper evenly before the medians and liners are brought together to form the board. To prevent warping, the source paper is passed through a preheater assembly that dries the source paper before it is processed by a machine for manufacturing corrugated board.
The preheater assembly typically includes a continuous web feeder, such as an unroller for feeding a continuous web of paper from a long sheet of paper wound around a core, a dryer, and a tension roller located between the feeder and the dryer for taking any slack out of the paper web. The dryer typically includes a large heated drum and two smaller idler rollers that keep the paper web in contact with the heated drum over a substantial portion of the circumference of the heated drum. From the dryer, the paper web travels to the machine for manufacturing corrugated board. Typically, the next stage in the assembly line is either a corrugator section, which flutes a paper web to create a median, or a single-facer section, which places a layer of adhesive between a median and a liner.
In order for the preheater to dry the paper properly, the paper web must be held tightly against the heated drum. If slack develops in the paper web, bubbles can form between the paper and the heated drum resulting in uneven moisture content in the paper exiting the dryer. Preventing slack from developing in the paper can be difficult, however, because the paper may have been rolled onto the core with uneven tension across the length of the paper roll. Typically, this causes one edge of the paper web to be taught while the other edge develops slack. This slack can remain in the web after it travels over the tension roller, over the first idler roller, and onto the heated drum, causing bubbles or loose edges to develop between the web and the drum.
In one conventional moving-web slack-reducing system designed to overcome this problem, the paper web is fed over a vertically-actuated tension roller. The vertical actuators, one typically placed at each end of the tension roller, allow each end of the tension roller to be lifted and lowered a small amount in an attempt to take any slack out of the paper web. But this solution is somewhat wanting in performance because removing the slack from the web requires precise positioning of the actuators. In addition, the tension tends to vary quickly across the paper web as the paper is unrolled. Removing the slack from the web under these conditions therefore requires fairly rapid and precise adjustments of the actuators, which are difficult to achieve at a reasonable level of investment.
Therefore, there is a need for a preheater assembly for a machine for manufacturing corrugated board that results in a paper web leaving the preheater assembly with a relatively even moisture content. There is a further need for a preheater assembly that removes the slack from a paper web without having to rely on fairly rapid and precise adjustments of a vertically-actuated tension roller.
SUMMARY OF THE INVENTION
The present invention satisfies the needs described above by providing a moving-web slack reducing system including a deformable tension roller, such as a brush-type tension roller having an outer surface defined by the ends of a plurality of bristles. The slack reducing system may be deployed in a preheater assembly for a machine for manufacturing corrugated board. The bristles of the deformable tension roller allow the outer surface of the tension roller to deflect both radially and in the cross-machine direction without binding to the paper web. The bristles may also deflect variably across the tension roller in the cross-machine direction. Thus, the deflection of the bristles adjusts automatically and virtually instantaneously to changes in the tension of the paper web to compensate for variations in tension across the web in the cross-machine direction. This allows the brush-type tension roller to take the slack out of the paper web without having to rapidly and precisely adjust any actuators.
Generally described, the invention is a slack reducing system for an assembly line that includes a continuous web feeder. An intermediate roller receives the web from the feeder and feeds the web further down the assembly line. A brush-type tension roller is positioned between the feeder and the intermediate roller so that the web contacts a portion of the outer surface of the tension roller as the web travels from the feeder to the intermediate roller. The brush-type tension roller includes an outer surface defined by the ends of a plurality of bristles, each of which may be crimped to form peaks and valleys.
According to another aspect of the invention, a preheater assembly for a machine for manufacturing corrugated board includes a continuous web feeder. A dryer receives the web from the feeder and feeds the web to a machine for manufacturing corrugated board. A tension roller including a deformable outer surface is positioned between the feeder and the dryer so that the web contacts a portion of the outer surface of the tension roller as the web travels from the feeder to the dryer. The dryer may include a heated drum and an idler roller that is positioned relative to the heated drum so that the web contacts a portion of the outer surface of the heated drum as the web travels from the feeder to the machine for manufacturing corrugated board.
Although the deformable tension roller may be deployed without vertical actuators, the tension roller may also be deployed with vertical actuators if additional control is desired. In this case, the tension roller includes a first vertical actuator for raising and lowering the first end of the tension roller with respect to a support structure, and a second vertical actuator for raising and lowering the second end of the tension roller with respect to the support structure. A controller, which is functionally connected to the first and second vertical actuators, is operative for varying the height of the first and second ends of the tension roller with respect to the support structure.
Accordingly, it is an object of the invention to provide a preheater assembly for a machine for manufacturing corrugated board that results in a paper web leaving the preheater assembly with a relatively even moisture content. It is a further object of the invention to provide a preheater assembly that removes the slack from a paper web without having to rely on fairly rapid and precise adjustments of a vertically-actuated tension roller.
REFERENCES:
patent: 2287768 (1942-06-01), Eckstein
patent: 2660218 (1953-11-01), Johnson et al.
patent: 2781535 (1957-02-01), Phillips et al.
patent: 2852791 (1958-09-01), Febinger
patent: 3018975 (1962-01-01), Kulicke, Jr.
patent: 3195159
Ball Michael W.
Corrugated Gear & Services Inc.
Gardnder & Groff, P.C.
Musser Barbara J.
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