Printing – Cleaning attachments
Reexamination Certificate
1999-04-20
2001-03-06
Hilten, John S. (Department: 2854)
Printing
Cleaning attachments
C101S483000
Reexamination Certificate
active
06196128
ABSTRACT:
DESCRIPTION
The present invention relates to methods and apparatus for cleaning particulate contamination from a substrate surface which may be a roller surface, more particularly to methods and apparatus for using a contact cleaning roller to pick up particles from a substrate surface which may be another roller surface, and most particularly to methods and apparatus for traversing a short contact cleaning roller axially along a substrate surface which may be the surface of a longer process roller for transferring contaminant particles from the process roller to the contact cleaning roller. The process roller may be a contact cleaning roller.
In many manufacturing processes involving substrates, for example, in continuous-web printing and in the coating of photographic films and papers, particulate contamination of the substrate surface can lead to reduced quality of the coated product and to increased waste. It is known to use a polymer-covered roller in rolling contact with a planar substrate to remove particles from the surface of the planar substrate ahead of the printing or coating point. It is also known to use a polymer-covered roller in rolling contact with another roller, for example, a process roller such as another contact cleaning roller, calendar roller, offset printing roller, and the like. The surface of such a polymer-covered roller (known in the art as a contact cleaning roller and also referred to herein as a CCR), may comprise a polymer having a high surface energy, for example, polyurethane or silicone rubber, or alternatively, a polymer exhibiting adhesive tack, such as any of the well-known tape adhesives. The CCR surface exhibits a greater attraction for particles than does the substrate surface, so that particles are transferred from the substrate to the CCR at the point of rolling contact.
A CCR may itself function as a conveyance roller, for example, in a string of web conveyance rollers, in which use the CCR may enjoy a substantial angle of wrap of the web, for example, a wrap angle of 90° or even greater. A conveyance roller as used herein is a roller whose position defines a portion of a web conveyance path. Such engagement by a CCR may be on either side of the web being conveyed. See, for example, U.S. Pat. No. 5,251,348 issued Oct. 12, 1993 to Corrado et al. A CCR may also function as a non-conveyance roller, that is, the web conveyance path is not a function of the presence or absence of the CCR. In such use, a CCR typically is positioned as a nip roller urged against a non-CCR conveyance roller (backing roller), the web passing therebetween, whereby the web is conveyed on a first or back side against the conveyance roller and is cleaned on a second or front side by the CCR. See, for example, U.S. Pat. No. 5,611,281 issued Mar. 18, 1997 to Corrado et al. which is hereby incorporated by reference.
Many substrates, for example, web substrates, have particulate contamination concentrated along the outer edges of the substrate surface which can lead to premature clogging and failure of a full-width CCR while more central portions of the CCR surface are still non-clogged and serviceable. The U.S. Pat. No. 5,611,281 patent discloses to prolong the useful life of a CCR between renewals (removal of accumulated particles) by oscillating the CCR axially while it is rolling along the substrate surface, thereby causing accumulating particles to be distributed as a broad band over a substantial portion of the axial length of the roller along each substrate edge.
Through use, the surface of a CCR becomes progressively clogged with removed particles and progressively loses cleaning effectiveness. Cleaning, also known as renewal, of a CCR surface may be accomplished through washing, for example, as disclosed in U.S. Pat. Nos. 5,275,104, 5,611,281, wherein a plurality of CCR's are alternably provided such that continuous cleaning of the substrate surface can be maintained while each CCR in turn is rotated out of service for off-line renewal, including drying. This is necessary because washing of a CCR while in service against a substrate risks undesirable transfer of cleaning fluid onto the substrate.
Alternatively, as disclosed in the '281 patent, a higher-tack CCR may be engaged to clean particles from a lower-tack CCR (which procedure is defined hereby as secondary cleaning) which itself has cleaned, or is actively cleaning, particles from some other substrate surface such as a web (which procedure is defined hereby as primary cleaning). For continuous primary cleaning, this arrangement requires continuous contact of the primary CCR with the substrate. Thus, a problem arises as to how to clean or renew the secondary CCR without reverse-contaminating the primary CCR and, indirectly, the substrate being cleaned.
Typically, a secondary CCR, like a primary CCR, comprises either a solid polymer covered roller or a length of adhesive tape wound on a core with the adhesive surface facing outwards. Renewal of either type of secondary CCR requires first that the roller be retracted from contact with the primary CCR to avoid contamination thereof. A solid polymer secondary CCR may then be washed automatically, as referenced above, or manually by an operator, either in place or after being removed to a washing station. A tape-type secondary CCR is renewed either by unwinding and discarding the exposed tape to present a fresh convolution or by replacing the roll of tape when spent, as disclosed in U.S. Pat. No. 4,009,047.
For some primary CCR installations, for example, those involving very long CCR's as in many paper and plastic web manufacturing processes, full-length secondary CCR's become prohibitively expensive or impractical. Adhesive tape may not be available in sufficient wound width, for example, four or five meters, to match the length of a primary CCR, and even if available, the viscous drag resulting from full-length contact can stall or prevent the primary CCR from turning as an idler roller in synchrony with the web being conveyed. Operator handling of such rolls for stripping of a spent adhesive convolution or for replacement of a spent roll can be cumbersome, difficult, and dangerous and can prove to be impossible in some situations, for example, in the dark conditions required for photographic manufacturing. Further, in installations wherein an adhesive-tape secondary CCR must be disposed below the primary CCR, the tape roll may sag in the middle under its own weight, preventing proper contact of the tape surface with the entire length of the primary CCR.
Thus there is a need for a method and apparatus for providing renewal cleaning of a primary CCR by a secondary CCR which permits easy, safe renewal of the secondary CCR, which apparatus may also be adapted to renewal cleaning of a primary CCR by means other than a secondary CCR. There is a further need for a method and apparatus wherein the motion and contact of secondary CCR with a primary CCR is completely controllable.
It is a principal object of the invention to provide an improved method and apparatus for safe, inexpensive, and simple renewal of a primary and/or secondary CCR.
It is a further object of the invention to provide an improved method and apparatus whereby a primary CCR may be effectively and reliably cleaned by a secondary CCR independent of the length or diameter of the primary CCR.
It is a still further object of the invention to provide an improved method and apparatus whereby a secondary CCR may follow a programmed sequence of motions for cleaning various portions of a primary CCR.
Briefly described, a system for cleaning a moving substrate includes a rail mounted adjacent to the substrate surface and substantially transverse to the direction of movement thereof. A carriage for supporting a contact cleaning apparatus, which may be, for example, a non-rotatable cloth web or sponge pad as disclosed in U.S. Pat. No. 5,275,104 which is hereby incorporated herein by reference, and preferably is a rotatable polymer-covered contact cleaning roller, is rollably deploye
Corrado Frank C.
Fischer James W.
Larsen Gary R.
Sweet Ronald W.
Hilten John S.
Nguyen Anthony H.
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