Plastic article or earthenware shaping or treating: apparatus – With means applying coating material to work or work contact... – Separate means applying material directly to shaping means,...
Reexamination Certificate
1999-06-17
2001-06-26
Davis, Robert (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With means applying coating material to work or work contact...
Separate means applying material directly to shaping means,...
C134S153000, C015S309100, C015S316100, C425S230000
Reexamination Certificate
active
06250902
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to embossing. More particularly, it relates to a method and apparatus for cleaning and preventing build up of deposits on an embossing roll during an embossing process.
BACKGROUND OF THE INVENTION
The process of embossing is widely used in the production of consumer goods. Manufacturers use the embossing process to impart a texture or relief pattern into products made of textiles, paper, synthetic materials, plastic materials, metals, and wood. Embossing a product can enhance the visual perception or improve the performance of the product. For example, embossing a paper product can result in a visually pleasing pattern on the paper or in the increased bulk and absorbency of the product.
Embossing is the act of mechanically working a substrate to cause the substrate to conform under pressure to the depths and contours of a pattern engraved or otherwise formed on an embossing roll. Embossing is accomplished by passing a substrate, or web, through one or more patterned embossing rolls set to apply a certain pressure and penetration depth to the web. As the web passes the embossing rolls, the pattern on the rolls is imparted onto the web.
The patterns on the embossing rolls can be mated or non-mated. In a pair of mated embossing rolls, the pattern on one of the rolls compliments identically, or “mates,” with the pattern on the other of the mated rolls. The pattern on a non-mated embossing roll does not match identically with the pattern on the other roll. Depending on the desired results, either type of embossing roll can be used.
A problem encountered during the embossing process is caused by the buildup of deposits on the embossing rolls. As the embossing roll works a web, fiber, stickies, and other deposits from the web stick to the surface of the embossing roll. The accumulation of deposits on the pattern on the embossing roll changes the depths and contours of the pattern that is imprinted into the web and impairs the embossing definition. Also, the unchecked accumulation of deposits might lead to vibrations in the embossing roll as it rotates with the web. This quick accumulation of deposits can damage or destroy a set of mated embossing rolls if the accumulated deposits are not removed from the rolls regularly. Thus, to ensure that the embossing process produces the desired results in a safe manner, the process must be stopped periodically to clean the deposits from the embossing rolls.
One approach to solving this problem is to attempt to clean loose fiber from the web before the web reaches the embossing roll. These types of web cleaning devices are widely described in the patent literature. A comprehensive, but non-exhaustive list includes U.S. Pat. Nos. 5,577,294; 5,490,300; 5,466,298; 5,304,254; 4,783,947; 4,643,775; and 4,594,748. However, these devices remove few, if any, stickies or pitch that is firmly embedded in the web. Furthermore, these inventions do not remove 100% of the loose fiber present.
Devices for cleaning deposits from embossing rolls, such as the device disclosed in U.S. Pat. No. 4,852,209, are very complicated and expensive. They usually require spraying water or solvent on the rolls and then removing the water or solvent. Usually there is some residual solvent which can itself lead to plugging of an emboss roll. Brush rolls are not an appropriate alternative because they do not remove firmly embedded deposits and the brush bristles fall off and end up in the product.
Another potential solution to the accumulation of deposits problem is to apply a lubricant solution to the surface of the embossing roll using spray nozzles. The lubricant prevents some fiber and sticky build up, by lubricating the surface of the embossing roll so that deposits do not attach to the surface.
However, using a spray nozzle to apply the lubricant or solvent solution creates additional problems. To cover the entire surface of the embossing rolls, the spray nozzles must usually be positioned 6 to 8 inches from the surface of the roll and 6 to 8 inches apart. With this positioning, the spray nozzles create a mist of lubricant around the embossing roll. Some of the mist stays in the air and the remainder settles on the embossing roll, the surrounding equipment, or on the floor, thereby wasting a significant amount of the sprayed material. The mist in the air creates a breathing hazard and the mist that settles on the floor creates other safety hazards. In addition to wasting the sprayed chemical and creating potential breathing and safety hazards, the mist leaves an uneven coating on the surface of the embossing roll. The uneven coating of lubricant is ineffective in preventing the accumulation of deposits because the surface areas having a thicker coating of lubricant actually trap the deposits. Also, the deposits stick to the areas of the embossing roll that do not get enough lubricant.
In light of the foregoing, there is a need for a device and a method by which the embossing rolls can be kept clean of deposits during the embossing process.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an apparatus and method for preventing the buildup of fiber on an embossing roll during the embossing process.
The advantages and purpose of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purpose of the invention will be realized and attained by the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises a method of cleaning embossing rolls. The method involves directing pressured air at the surface of the embossing roll by an air nozzle that forms an air knife to dislodge deposits from the roll. A lubricant and/or solvent solution can be mixed with the air and sprayed along the width of the embossing roll.
The present invention also concerns a method of embossing a web, where the web is passed between a pair of embossing rolls to impart the pattern of the embossing rolls upon the web. Pressured air, with or without the lubricant, is then directed at the surface of the embossing roll to dislodge deposits from the roll. The present invention further concerns an embossed paper product made with the method of the present invention.
According to another aspect, the invention concerns an apparatus for preventing the accumulation of deposits on the surface of an embossing roll. The apparatus has an air nozzle and a source of pressured air. In another embodiment, the apparatus has a means for mixing a lubricant and/or solvent solution into the pressured air. The nozzle has an air inlet and an elongated narrow slit opening that extends for the width of the embossing roll. The compressed air source forces air through the nozzle forming an air knife that is directed onto the surface of the embossing roll. A lubricant and/or solvent solution can be mixed into the air supply of the air knife and sprayed onto the surface of the embossing roll to prevent the accumulation of deposits on the surface of the embossing roll.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
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patent: 4839227 (1
Dwiggins John H.
Heath Michael S.
Hornby James C.
Kuehl Orlin C.
Pollock Rodney E.
Davis Robert
Del Sole Joseph S.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Fort James Corporation
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