The present invention relates in general to a printing blanket sleeve and in particular to a seamless printing blanket sleeve having a replaceable printing surface.
A typical blanket cylinder on an offset printing press includes an axially extending groove, or lock up gutter with clamping segments. Printing blankets are provided in sheets that are wrapped around the blanket cylinder such that the opposite ends of the printing blanket are inserted and clamped in the groove. Because the loose ends of the blanket must be secured to the cylinder, the surface of the blanket when mounted will have a gap where the edges are drawn. As a consequence, print quality, speed of operation, and available print region dimensions are affected. Press downtime, including printing blanket change over time, can also be excessive.
These problems can be minimized where the printing blanket is provided as a gapless sleeve that is capable of mounting onto the blanket cylinder. Because the sleeve is essentially stretched while on the blanket cylinder however, the sleeve is exposed to considerable peripheral and circumferential forces. Additionally, while operating the press, the blanket sleeve is exposed to high revolution speeds and impact with other components of the press, including a plate cylinder with printing plates. As such, the printing blanket sleeve will eventually dynamically fatigue. Where the printing blanket sleeve has experienced sufficient dynamic fatigue, print quality will be affected, and the printing blanket sleeve must be replaced. However, it is usually either the printing surface, or the adhesive that holds the printing surface to the first internal layer, that will fail. The remaining layers are often functionally intact.
Currently, some fatigued printing blanket sleeves are discarded. This leads to considerable waste and cost as the materials used to construct the base layer and internal layers constitute a significant portion of the total materials cost for the sleeve production. Alternatively, the fatigued printing blanket sleeves are sent back to the manufacturer to be reconditioned or “recapped”. While reconditioning allows for recycling of certain reusable portions of the fatigued printing blanket sleeve, the press operator must ship the entire printing blanket sleeve back to the manufacturer. The manufacturer must remove the worn portions of the printing blanket sleeve, and assemble a new printing surface and internal components to the printing blanket sleeve. This causes considerable cost to the manufacturer. Further, some sleeves returned to the manufacturer have damage to the nickel base from shipping or handling and cannot be reprocessed.
Therefore, there is a need for a gapless printing blanket that allows for a simple changeover of the printing surface of a fatigued printing blanket sleeve, where the changeover can be accomplished directly on the press, or on-site, near the press.
The present invention overcomes the disadvantages of previous printing sleeves by providing a renewable printing sleeve where the printing surface and optionally, one or more support layers, are removed from the printing sleeve and replaced.
According to one aspect of the present invention, a printing blanket sleeve includes two separable sections, including a carcass sleeve and a face sleeve. The carcass sleeve comprises a base sleeve, and preferably one or more internal layers including a compressible layer. The face sleeve comprises a first internal surface and a printing surface. The compressible layer may alternatively be included with the face sleeve between the first internal surface and the printing surface. The face sleeve is installed over the carcass sleeve to define a printing blanket sleeve. When the printing blanket sleeve is installed on a blanket cylinder of a printing press, the carcass sleeve and the face sleeve rotate as an integral unit. Should the printing surface excessively wear or fatigue, the face sleeve may be replaced. However, the carcass sleeve may be recycled for numerous lifetimes by installing a new face sleeve over the existing carcass sleeve.
Further, the printing blanket sleeve is arranged such that the user of a printing press can preferably replace the face sleeve on-site, and more preferably at or near the machinery, so that there is no longer a need to either discard the entire printing blanket sleeve, or alternatively to send the printing blanket sleeve back to the manufacturer to be recapped.
The following detailed description of the preferred embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals, and in which:
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that mechanical changes may be made without departing from the spirit and scope of the present invention. Reference is made to the figures, which illustrate printing blanket sleeve construction according to the present invention. It will be appreciated that these are diagrammatic figures, and that the dimensions are not shown to scale.
As shown in
In practice, various ones of the components of the printing blanket sleeve 100 are combined for form two discrete sleeves that may be assembled such that the two sleeves rotate on the blanket cylinder 112 as an integral unit. However, the sleeves may be separated so that the printing face 110 may be replaced and one or more of the underlying components recycled for multiple lifetimes as more fully explained herein. Each of the components of the printing blanket sleeve 100 are illustrated in cut out fashion progressively cut away from the left hand side of
The base sleeve 102 is preferably electroformed out of nickel. However, other suitable materials may be used including stainless steel, aramid fibers, carbon fiber reinforced epoxy, fiberglass reinforced plastic, or fiberglass reinforced polyester resin.
The first reinforcing layer 104 imparts a high coefficient of friction to the surface of the base sleeve 102. For example, the first reinforcing layer 104 may comprise a polymer wound cord, fabric, wound fibers such as polyester, cotton, fiberglass, cotton-wrapped polyester, rayon, carbon filaments, or other high modulus synthetic or organic fibers. Suitable synthetic fibers include for example, aramid fibers and fiberglass or polyester threads available from a variety of sources. The first reinforcing layer 104 is not required to practice the present invention. However, the first reinforcing layer 104 provides additional rigidity to the base sleeve 102, thus reducing the chance of damaging the base sleeve 102 during handling.
The compressible layer 106 is an elastomer having the required properties to perform applications typically associated with heat set web offset printing. The compressible layer 106 may be formed using techniques as known in the art. For example, an elastomeric compound including known processing, stabilizing, strengthening and curing additives may be used to form the compressible layer 106. Any suitable polymeric material that is considered a curable or vulcanizable material can be used, including for example, natural rubber, styrene-butadiene rubber (SBR), ethylene/propylene/nonconjugated dieneterpolymer rubber(EPDM), butyl rubber, neoprene, butadiene, acrylonitrile rubber (NBR), or polyurethanes. An elastomer that is resistant to solvents and ink is preferable. For example, the compressible layer 106 may include microspheres impregnated into an elastomer as disclosed in U.S. Pat. No. 4,770,928 entitled, “METHOD OF CURING A COMPRESSIBLE PRINTING BLANKET AND A COMPRESSIBLE PRINTING BLANKET PRODUCED THEREBY”, and herein incorporated by reference.
The compressible layer 106 secures to the first reinforcing layer 104 using techniques as are known in the art. For example, in construction, a printing blanket sleeve comprises a nickel base sleeve, a first reinforcing layer, and a compressible layer applied over the reinforcing layer using conventional spreading machines. Alternatively, in a second construction, a compressible layer is formed directly onto a nickel base sleeve using pour or injection molding techniques. The compressible layer 106 may alternatively be applied using extrude spray spun processes or other techniques as is known in the art. Further, one skilled in the art will recognize that the compressible layer 106 may be substantially vulcanized prior to assembly, or may be secured to either the first reinforcing layer 104 or the base sleeve 102 by means of a suitable adhesive. Additionally, the compressible layer 106 may require additional processing and preparation. For example, it may be necessary to grind the compressible layer 106 to a desired dimension before completing assembly of the printing blanket sleeve 100.
The second reinforcing layer 108 is optional, and preferably comprises a layer of non-stretchable material. For example, the second reinforcing layer 108 may be a layer of woven or nonwoven fabric, a reinforcing film such as MYLAR (polyester), a reinforced film such as carbon fiber or aramid fiber, cord, fiberglass or a surface layer of hard polyurethane. Additionally, the second reinforcing layer 108 may be a sleeve similar in construction and materials as the base sleeve 102 described herein. Where the second reinforcing layer 108 is formed from a fabric layer, the material may include plain woven fabric from high grade cotton yarns, which are free from slubs and knots, weaving defects, seeds, etc. The fabric may also be rayon, nylon, polyester, or mixtures thereof.
The printing face 110 may be any printing surface as is known in the art. For example, the printing face 110 may comprise a strip formed around and adhesively held to the second reinforcing layer 108. Alternatively, the printing face 110 may comprise a gapless tubular composite such as an extruded face tube as is known in the art. The printing face 110 is secured to the surface of second reinforcing layer 108. For example, the printing face 110 may be adhesively affixed to the second reinforcing layer 108 using a rubber cement. It shall be observed that where a second reinforcing layer 108 is not used, the printing face 110 is secured to the compressible layer 106.
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According to one embodiment of the present invention, the carcass sleeve 214 is positioned on the blanket cylinder 212 such that the through apertures 224 align substantially in register with aeration holes 226 provided along the surface of the blanket cylinder 212. The carcass sleeve 212 remains in position on the blanket cylinder while face sleeves 216 are mounted thereon, and removed therefrom. This allows the printing surface of the printing blanket sleeve 200 to be changed over directly on the printing press. Pressure is selectively applied from a source coupled to the blanket cylinder 212 as is known in the art. For example, the blanket cylinder 212 has a central lumen (not shown) and a plurality of passages extending radially from the central lumen. A source of pressurized gas communicates with the central lumen in the blanket cylinder 212, the plurality of passages and the inner surface of the printing blanket sleeve 200.
The first internal surface 220 is elastically expandable diametrically in a slight amount. As the face sleeve 216 is slid towards the carcass sleeve 214, the pressure forced through the aeration holes 226 and associated through apertures 224 causes expansion of the inside diameter of the face sleeve 216 radially outward, thus providing creep allowing the face sleeve 216 to slip on and off the carcass sleeve 214. Once the face sleeve 216 is properly situated on the carcass sleeve 214, the pressure source is removed. As such, the inside diameter of the face sleeve 216 contracts generally causing a tight frictional relationship to exist between the carcass sleeve 214 and the face sleeve 216. As such, the carcass sleeve 214 and the face sleeve 216 will operate as an integral unit when properly installed on a suitable blanket cylinder. The face sleeve 216 is expanded under moderate air pressure, for example, less than 100 psi, and slipped over the carcass sleeve 214 while in an expanded state.
The carcass sleeve 214 may optionally include an expansion/contraction valve 232 arranged to selectively provide expansion and contraction to the face sleeve 216. Such an arrangement may be desirable where the blanket cylinder does not provide aeration holes or where provided aeration holes do not sufficiently align with the through apertures provided through the carcass sleeve 214. An air hose or other source (not shown) is selectively coupled to the expansion/contraction valve 232 for providing the creep necessary to slip the face sleeve 216 over the carcass sleeve 214. Where an expansion/contraction valve 232 is provided on the carcass sleeve 214, it is not necessary that the apertures 224 need only be able to receive pressure radially outward. Therefore, the carcass sleeve 214 may require duct work or other passages to couple the expansion/contraction valve 232 to each of the plurality of apertures 224. It shall be observed that the face sleeve 216 may be wider than the carcass sleeve 214 under this arrangement to allow installation, trim, and the like to fit properly.
As an alternative to leaving the carcass sleeve 214 on the blanket cylinder 212, the entire printing blanket sleeve 200 may be removed from the blanket cylinder 212 prior to replacing the face sleeve 216. This approach is currently preferred over changing the face sleeve 216 while leaving the carcass sleeve 214 on the blanket cylinder 212. The printing blanket sleeve 200 is attached to a mounting frame (not shown), a new face sleeve 216 is placed on the carcass sleeve 214, and then the printing blanket sleeve 200 is replaced on the blanket cylinder 212. The mounting frame may include a pressure source that aligns with the through apertures in the carcass sleeve 214, or the carcass sleeve 214 may include an expansion/contraction valve 232. In either embodiment, the removal of the face sleeve 216 from the carcass sleeve 214 is substantially as described above.
It shall be appreciated that other mechanical bonding methods may be used with the present invention other than pure friction to secure the carcass sleeve 214 to the face sleeve 216. This may be desirable because under certain circumstances, through holes may cause printing problems. For example, a spline and taper lock arrangement (not shown) may be used where grooved passages are cut or molded on either the carcass sleeve 214 to fit matching forms on the face sleeve 216. Alternatively, “V” notch/groove techniques as are known in the art may be used. The surface of the carcass sleeve 214 may further be knurled. Additionally, friction materials with high coefficients of friction such as polyurethanes and nitrites may be used as is known in the art.
Referring to
After removal of the heat, cooling completes the bonding process. The bonding adhesive 234 can be applied as an extruded tube, spiral wrapped tape, or directly coated. For example, bonding can be achieved by first applying heat to a predetermined level to melt the bonding adhesive 234. The bonding adhesive 234 will become a fluid when melted, allowing the face sleeve 216 to be slid onto the carcass sleeve 214. Then, by applying a higher heat, the bonding adhesive 234 cures and sets. The face sleeve 216 can be removed from the carcass sleeve 214 by applying a removal force, for example by heating the printing blanket sleeve 200 and removing the face sleeve 216 before the temperature cools sufficiently to reactivate the bonding properties of the bonding adhesive 234. When utilizing a heat activated adhesive to bond the face sleeve 216 to the carcass sleeve 214, it may be necessary to recondition the outer surface of the carcass sleeve 214 prior to installation of the new face sleeve 216. It shall be observed that the inside diameter 216ID of the face sleeve 216 need not be smaller than the outside diameter 214OD of the carcass sleeve 214 when using the bonding adhesive 234. Rather, the face sleeve 216 should be dimensioned to allow the face sleeve 216 to slide over the carcass sleeve 214.
As an alternative to the heat activated adhesive, the bonding adhesive 234 may be a solvent activated bonding adhesive agent or catalytic adhesive applied between the face sleeve 216 and the carcass sleeve 214. The bond is activated when the solvent is completely evaporated. To remove the face sleeve 216 from the carcass sleeve 214, a removing force is applied. For example, the face sleeve 216 is mechanically cut off, using care not to damage the carcass sleeve 214. As with the use of the heat activated adhesive, some reconditioning of the carcass sleeve 214 may be required prior to installing the new face sleeve 216. It shall be appreciated that other chemical adhesive systems can be utilized to secure the face sleeve 216 to the carcass sleeve 214.
It shall be observed that the printing blanket sleeve 200 may comprise any number of layers that can be divided between the carcass sleeve 214 and the face sleeve 216 in any number of ways so long as there is at least two separable sleeve components that can be mated in a manner such that the assembly of the carcass sleeve 214 and the face sleeve 216 operate as an integral unit when installed on a printing press. Preferably, the face sleeve 216 may be replaced from the carcass sleeve 214 either while the carcass sleeve 214 remains on the printing press (not shown) or alternatively, both the carcass sleeve 214 and the face sleeve 216 are removed from the printing press and the face sleeve 216 is replaced on-site, preferably near the printing press.
Referring to
A printing blanket sleeve 300 is mounted on a blanket cylinder 312, and includes carcass sleeve 314, and a face sleeve 316. The face sleeve 316 is mounted onto, and secured to the carcass sleeve 314 such that lateral and rotational motion of the carcass sleeve 314 with respect to the face sleeve 316 is prevented. As such, the carcass sleeve 314 and the face sleeve 316 will rotate as an integral unit when properly installed on a suitable blanket cylinder 312.
The carcass sleeve 314 includes a base sleeve 302 and a compressible layer 306. It shall be observed that the carcass sleeve 314 may optionally include a first reinforcing layer 304 between the base sleeve 302 and the compressible layer 306 as described more fully herein. Further, a second reinforcing layer 308 may be applied over the compressible layer 306.
The face sleeve 316 includes a first internal surface 320, and a printing face 310 installed over the first internal surface 320. The first internal surface 320 may be the inside surface of an existing layer, or may be a layer specially provided to temporarily bond with the carcass sleeve as discussed above. For example, the printing face 310 may comprise an extruded face tube as discussed herein. The inside surface of the extruded face tube 310 may be prepared to have the properties required to releasably bond with the carcass sleeve, such as when using certain mechanical, chemical or adhesive bonding techniques. Optionally, one or more reinforcing layers and/or a layer specifically intended to releasably bond to the carcass sleeve may be required. For example, the printing face 310 may be secured to a sleeve such as a nickel sleeve. The nickel sleeve may be used to releasably secure to the carcass sleeve using frictional forces as more fully described herein.
The face sleeve 316 is mounted onto the carcass sleeve 314 such that a relationship exists therebetween to prevent lateral and rotational motion of the carcass sleeve 314 with respect to the compressible face sleeve 316. Referring to
It shall be appreciated by those skilled in the art that the printing blanket sleeve 300 differs from printing blanket sleeve 200 in the arrangement of the compressible layer and reinforcing layers. In the printing blanket sleeve 200, the compressible layer 306 is integral with the face tube 310. In contrast, the printing blanket sleeve 300 includes the compressible layer 306 integral with the carcass sleeve 314. Otherwise, the construction, materials, and techniques of assembly are identical to those described herein.
Further, the use of the bonding adhesive 234 discussed with reference to the two piece sleeve constructions discussed with reference to
Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
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