Winding – tensioning – or guiding – Material guide or guard – Fluid suspension
Reexamination Certificate
2001-03-20
2003-03-18
Mansen, Michael R. (Department: 3653)
Winding, tensioning, or guiding
Material guide or guard
Fluid suspension
C226S097100, C034S642000, C242S615200
Reexamination Certificate
active
06533217
ABSTRACT:
FIELD OF THE INVENTION
The invention is related generally to web-processing apparatus and, more particularly, to apparatus for processing a coated web and air-turn apparatus used to support the web during processing.
BACKGROUND OF THE INVENTION
In many manufacturing or processing operations material, in the form of a material web, is coated or treated with various inks, resins and other substances in order to impart desired properties to the material. Web materials processed in this manner include, for example, glass fiber, paper, film and metals. The coating process typically involves unwinding the material from a supply roll, applying the coating, drying the coated web and re-winding the coated web onto a take-up roll or otherwise processing the coated web. The coating is typically a liquid and is applied to one or both sides of the web or by impregnating the web by, for example, immersing the web in a bath or spraying the coating on the web.
An important limitation with respect to the amount of web material that can be processed during a given unit time is the rate at which the web material can be dried following coating. It is important to dry the web rapidly because wet coating can be damaged or removed by contact with rollers and other coating apparatus components. Moreover, the web material often cannot be re-wound or processed further until the web coating has dried to a predetermined extent.
Web dryers are commonly used to process the coated web. The dryer increases the rate at which the coating is dried thereby increasing the rate at which the web can be processed. Typically, the web dryer is positioned along the path of the moving web downstream of the coating apparatus and may include air jets or heat sources to dry the web coating. In coating operations known as “pre-preg” coating operations, the web is moved through the dryer following coating at rates ranging from about 40-80 feet/minute to as high as 100 feet/minute. In other coating and processing operations the web speed may be much greater. The path of the web through the dryer can be as long as required to adequately dry the coating.
While web dryers are highly effective at increasing the rate at which the coating dries, they are not without certain disadvantages. One potential disadvantage is that dryers have a large footprint and occupy a significant amount of floor space at the operator's facility. One solution to this dryer-size-related problem is to provide plural parallel drying sections (rather than a single linear dryer section) and direction-changing apparatus to direct the web through the parallel dryer sections. Such an arrangement can reduce the amount of space required for the dryer.
In vertical dryers, cylindrically shaped, chilled rollers are used to change the direction of web movement. Chill rollers are well known and are commercially available, for example, from the F.R. Gross Company of Stow, Ohio. After initial drying in a first vertically-oriented drying section the web is then directed over, for example, paired chill rollers, through a 180° direction change, and through a second vertically-oriented drying section to complete the drying process. In such an operation, the web comes into direct physical contact with the chill rollers as the direction of web movement changes.
However, the use of such direction-changing chill rollers may be less than satisfactory in certain coating operations, particularly where the web is impregnated with coating material or where it is desired to apply coating to the web side facing the roller. Any such contact should be avoided because such contact can potentially damage any not-yet-dried coating material on the web. For example, the coating could, in certain circumstances, become adhered to the roller or the coating could be scraped away from the web by contact with the roller surface. Cooling of the chill roller minimizes potential adherence of coating to the roller. However, this is not a complete solution because any contact between the roller and coating creates the possibility that the coating will attach to the roller or otherwise become damaged.
In a further effort to minimize this contact-related problem, manufacturers of dryer apparatus have been required to provide refrigeration apparatus to cool the web and the web coating before the web contacts the chill roller. The refrigeration apparatus is provided in the form of a separate cooling zone or chamber adjacent the first chill roller. Refrigeration apparatus is provided to reduce the temperature in the cooling zone thereby cooling the web and web coating. Cooling of the web in this manner has been found to reduce, but not completely eliminate, adherence of coating material to the roller. As mentioned, the cooled web may be re-heated after passing over the chill rollers in order to complete the drying process.
Use of such refrigeration or chilling apparatus includes certain potential disadvantages. One potential disadvantage is that the cooling process is energy intensive both with respect to the energy required to cool the web but also with respect to the additional energy needed to reheat the cooled web in the downstream dryer sections. Another disadvantage is that alternate heating and cooling of the web reduces the rate at which the web can be processed through the dryer thereby reducing dryer efficiency. A further potential disadvantage of the cooling process is the additional cost of the refrigeration and related equipment used to cool the web.
Yet another possible disadvantage of the cooling process stems from the increased maintenance costs required to avoid potential contamination of the web as the web passes through the cooling section or sections. Contamination of the web could potentially occur as evaporating solvents and other materials (such as dirt or airborne particulates) condense and/or collect on the cool surface areas of the dryer within the cooling section. These materials can flake off and collect on the web and web coating possibly contaminating the web. Any such contamination should be avoided.
Removal and cleaning of the potential contaminates from the cooling section is a labor-intensive project which must be performed on a frequent basis increasing the cost of the coating operation. Further increasing the cost of operation is the fact that the processing line must typically be shut down for the cleaning to take place. This results in disruption of the manufacturing process.
The foregoing problems involving potential undesired contact between a support and/or direction-changing roller and a coated web surface facing the roller are present in other types of web-processing operations. For instance, in web laminating operations it is often necessary to change the direction of web movement in order to process the web, for example by steam moisturizing of the web before passage of the web into a laminator apparatus. However, conventional chill roller apparatus have proven unsatisfactory for this purpose because it is possible to change the web direction only about 180° without contacting the coated side of the web. As a result, less-than optimal processing line configurations have been developed simply because of the inability to change web direction without contact between the roller and the coated surface of the web.
Improved web-processing apparatus which would facilitate an improvement in the quality of products manufactured in coating operations, which would facilitate the use of more compact and efficient dryers and processing equipment used in coating operations and which would generally make processing operations more efficient would represent an important advance in the art.
OBJECTS OF THE INVENTION
It is an object of this invention to provide improved web-processing apparatus overcoming some of the problems and shortcomings of the prior art.
An important object of this invention is to provide improved web-processing apparatus which includes apparatus for changing the direction of web movement yet does not require a cooling section upstream of the web direct
Faustel, Inc.
Jansson & Shupe & Munger Ltd.
Mansen Michael R.
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