REINFORCED HARD POROUS INKING ROLL ASSEMBLY

Abstract: Method of making reinforced hard porous inking roll assembly (10). The inking roll assembly (10) comprises a hard porous material (20) suitable for inking, the improvement comprising a hard ink-resistant mold material (22) that remains and encompasses a substantial portion of the outside surface of roll (18) to provide reinforcement therefore. The method comprises metering, in increments, polymeric material (32) into a mold (22) to form hard porous material (20), and applying pressure to the mold (22) and polymeric material (32) at each increment. After mold (22) is filled with polymeric material (32), the polymeric material (32) is cured. The roll (18) is cooled and a strip of mold material (22) is milled to expose a small portion of hard porous inking material (20) in a straight strip (24) parallel to longitudinal axis (34) of roll (18).

Description: - 1 - REINFORCED HARD POROUS INKING ROLL ASSEMBLY Technical Field The present invention relates to a printing assembly, an inking roll used in said printing assembly, and a method of making said inking roll. Background Art In some prior art printing machines, a multi-color print mechanism is used in which the print mechanism comprises a cylinder that is approximately one inch in diameter and approximately six inches long, with a number of inking rolls being embedded in the cylinder. The inking rolls of the printing assembly are approximately one quarter inch in diameter, and are uniformly spaced in the cylinder. If desired, each of the inking rolls may be inked with a different color ink. Because the inking rolls are substantially permanently attached to the printing assembly, when any of the inking rolls is worn, or the ink on any of the rolls is depleted, the entire assembly is discarded. Since the inking rolls used with the printing assembly are about 1/4 inch in diameter, it is difficult to machine such rolls individually without breaking. Also, a roll having such a small diameter cannot be molded due to warping and breaking during demolding. Accordingly, there is a need in the art for making a printing assembly in which the inking rolls are interchangeable, such that all of the rolls, or one individual roll, may be exchanged without having to discard the entire printing assembly. There is also a need in the art for an - 2 - inking roll that is designed to transfer ink only to the intended document, and has an ink-free surface which can be handled by the operator. Also, there is a need in the art for an inking roll having reinforcement for added strength. It is known in the art to make a printing roll by filling a glass cylinder with polymeric material, curing the material, and then breaking the glass mold to expose the printing surface, as is described by Christie in U.S. Patent 3,100,676. It is also known in the art to provide an inking roll in which a portion does not ink, as is described by Williams in U.S. Patent 4,024,816. Disclosure of the Invention Pursuant to one aspect of the present invention, there is provided a printing assembly comprising a print mechanism that comprises a rigid cylinder having a plurality of inking rolls attached thereto. The printing assembly is characterized in that the inking rolls are adapted to be replaced individually, with means being provided for effecting separate attachment, removal, and replacement of individual rolls. Pursuant to another aspect of the invention, there is provided an inking roll comprising a hard porous material that is suitable for inking. The hard porous inking material of the roll is encompassed by an ink-resistant material over a substantial portion of the outside surface of said roll to provide reinforcement therefor. Pursuant to a further aspect of the present invention, a method is provided for making an inking roll, comprising the steps of molding a hard porous material in the shape of a roll by - 3 - dosing or metering into a mold the polymeric material used to form said hard porous material. Pressure is applied to the polymeric material in the mold at various stages during the filling process. After the mold is filled, the polymeric material is cured or sintered in the mold. After cooling the roll of polymeric material, a straight strip of the mold material is milled to expose a small portion of the hard porous inking material of the inking roll, with this exposed portion forming a straight strip that is parallel to the longitudinal axis of the roll. Brief Description of the Drawings The features of the present invention, and its technical advantages, can be seen from the following description of a preferred embodiment, together with the claims and the accompanying drawings, in which: FIG. 1 illustrates a perspective view of a present preferred embodiment of the printing assembly of the invention; FIG. 2 illustrates an exploded view of a mechanism of the invention by which an inking roll is attached to the printing assembly; FIG. 3 illustrates a method of the invention by showing a mold that is partially filled with polymeric material; FIG. 4 illustrates a completed inking roll made according to the invention; and FIGS. 5-7 illustrate inking rolls having alternative shapes. Best Modes for Carrying out the Invention Reference is now made to FIG. 1, which illustrates an inventive printing assembly, which is generally represented by reference number 10. - 4 - The printing assembly 10 comprises a rigid cylinder 12, plates 14 that have a central hole 11 for attachment to the cylinder 12 and peripheral holes 16, and inking rolls 18. The rigid cylinder 12 is the core of the printing assembly 10. The round rigid plates 14, which have an inside diameter that is greater than the diameter of cylinder 12, are attached at each end the latter by welding or cementing. The holes 16 are provided in the peripheral edges of the plates 14 to provide, in part, for attachment of the inking rolls 18 to the rigid plates 14. The holes 16 in the plates 14 are aligned from end to end on the cylinder 12 in such a way that when the ends 21 of the inking rolls 18 are inserted into the holes 16, the inking rolls 18 are aligned substantially parallel to the longitudinal axis of the cylinder 12 and the printing assembly 10. In its operation, each inking roll 18 of the printing assembly 10 may, if desired, be inked with different color ink. The operator, to print in a particular color, needs only to rotate the printing cylinder 10 so that the inking roll 18, having the desired color of ink, is properly oriented, and locked into position with respect to the document being printed. In the illustrated embodiment of the present invention, the printing assembly 10, including the inking rolls 18, is approximately 6 inches long and is about 1 inch in diameter. The inking rolls 18 are also about 6 inches long, and may be of any diameter which may be required for a specific purpose. A representative inking roll may have a diameter of about 1/4 inch. In the illustrated embodiment, individual - 5 - inking rolls 18 are adapted to be replaced individually, as needed, when they become worn or the ink supply is expended. This contrasts with prior art printing assemblies, in which the entire assembly must be discarded when one of the inking rolls is expended. Reference is now made to FIG. 2, which illustrates a mechanism by which individual inking rolls 18 may be removably attached to the printing assembly 10 of the invention. A generally semicircular clip, generally designated by reference number 26, is attached by, for example, welding or cementing, to one of the plates 14 in close proximity to one of the holes 16. An inking roll 18 is cut to a length such that when this inking roll 18 is inserted between the plates 14 of the printing assembly 10, the ends 21 partially enter holes 16. Clip 26 comprises a generally semicircular holding area 30 for receiving an inking roll 18 therein, and also comprises ends 28 that are adapted to hold an inking roll 18 in place. A locking mechanism 29, which may comprise a wire spring, may be attached to clip 26 in such a way that the protrusion 31 of the locking mechanism 29 contacts hole 16, and the protrusion 33 contacts inking roll 18 at notch 25. The locking mechanism 29 is provided to prevent rotation of the inking roll 18 on the printing assembly 10. Other means of attaching and locking an inking roll 18 in a printing assembly will be readily apparent to those skilled in the art, and all such means are intended to be included in the present invention. Clip 26 is preferably made of a resilient material, and has an arc length, as measured between ends 28, of more than a half circle, such - 6 - that when an inking roll 18 is pressed into clip 26, the ends 28 are pushed apart, so that there is a wider gap between the ends 28 to permit entry of the inking roll 18 into the holding area 30. After entry of the inking roll 18 into the holding area 30, the ends 28 return to their normal position, thus holding the inking roll 18 in place. The inking rolls are disposed in the printing assembly in such a way that a strip 24 of hard porous polymeric material 20 is exposed to the document being printed when the cylinder 12 is rotated to the proper position. Ink-resistant cover material 22 provides reinforcement for the inking roll 18, and makes it possible to insert and remove the inking roll 18 from the printing assembly 10 without mess, since the operator can handle the inking roll 18 by the ink-resistant cover material 22 when the inking roll 18 is changed. A hard porous polymeric material 20, having interconnected passages and voids, is used as an inking medium in the inking roll 18. The particular polymeric material 20 used is preferably inert to the inking compositions that are used. When the inking roll 18 is inked, the ink seeps into the interconnected passages and forms reservoirs of ink in said passages and in said voids. Any polymer known to be useful for this purpose can be used. Preferably, the polymer which may be used to form said hard porous inking roll will be a sintered blend of thermoplastic and thermoset materials, such as a blend of vinyl and polyethylene, phenolic and stabilizers. The hard porous polymer 20 used in the inking roll 18 may be made by any means known in the art for making such a material. In the preferred method of making a printing roll 18, the raw polymer 32 is provided in a particulate form, said particles preferably being of a size in the range which retains about 3% of said particles on a 50 mesh screen. In the preferred embodiment of the method, as illustrated in FIG. 3, polymer 32 is metered or dosed into mold 22 in increments, and pressure is applied to polymer 32 and mold 22 at each increment to reduce the possibility of air pockets being formed in polymer 32. After mold 22 is filled, the ends are capped, and the polymer 32 and the mold 22 are subjected to a curing or sintering step at a temperature, pressure and for a time suitable for the particular polymer 32 and the mold material used, to cause the particles to adhere to one another in a solid mass, without changing their individual particle shapes. The material used in mold 22 is rigid to provide reinforcement for the inking roll 18, and is inert to the inking compositions that are used. In the illustrated embodiment of the invention, the material used in cylinder 12, plates 14 and mold 22 may be selected from the group comprising aluminum, steel, hard vinyl, hard phenolics, hard plastics, hard rubber, polymer blends and composites thereof. Aluminum is preferred. By providing polymer 32 in particulate form, the presence of interconnected passages and voids in the polymer is assured because when the polymer is cured or sintered below its melting point, there will be gaps left between individual particles, as is described in U.S. Patent 4,024,816 to Williams et al, and by Rockoff in U.S. Patent - 8 - 3,336,244. It will be recognized by those skilled in the art that a hard porous polymeric material also can be made by the well known salt leaching process as is described in U.S. Patent 4,025,685 to Haren et al. After the polymeric material and mold are cured, and cooled, the assembly thus formed is milled to remove a straight strip of the mold 22 on a line parallel to the longitudinal axis 34 of the inking roll 18, as is illustrated in FIG. 4. The milling operation exposes hard porous polymeric material 20 in a straight strip 24. This straight strip 24 is used as the inkling medium when the inking roll 18 is used in a printing operation. The assembly is then cut to the required length. In an illustrative embodiment of the method of the invention, approximately 1/4 of the polymeric material used to form the hard porous compound was metered into a phenolic mold. Pressure was applied to the mold, and to the polymeric material. This cycle was repeated four times until the mold was filled, whereupon end caps were placed on the mold. The assembly was placed in a 305°F oven, and cured for 1.5 hours. The molded assembly was removed from the oven and cooled. The cooled assembly was placed on a milling machine, and a 1/8 inch wide strip of phenolic material was removed from the outer surface. The 1/8 strip of material was removed in a straight line, parallel to the longitudinal axis 34 of the roll, leaving the strip 24 of hard porous polymeric inking material exposed. The strip 24 of exposed hard porous inking material is the inking medium for the print mechanism described above. The assembly was cut to the length needed for an inking roll, and the hard porous material was inked. As is apparent, the mold becomes part of the inking roll. Thus, the inking roll 18 of the assembly 10 comprises the hard porous polymeric material (inking material) which is encompassed by a hard, ink-resistant material (the mold). The inking medium of the inking roll 18 comprises a single strip 24 of exposed hard porous material, which has been exposed by milling a small strip of the hard, ink-resistant surface material. The inking roll assembly 10 of the invention can be inserted into an existing multicolored print mechanism. Each inking roll 18 may be changed as that particular roll is expended. The master cylinder of the multicolor print mechanism may be reused since each individual inking roll 18 is discarded as it is expended. The hard ink-resistant material which encompasses the inking material makes it possible for the inking roll 18 to be handled without getting ink on the operator. Although it is preferred that a round inking roll be used, the inking roll may be made in the shape of a hexagon, a square, a triangle, or any other suitable geometric shape. Inking rolls 18 having alternative geometric shapes are illustrated in FIGS. 5-7. While present embodiments of this invention and methods of practicing the same have been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced within the scope of the following claims.

Claims: AMENDED CLAIMS [received by the International Bureau on 3 March 1987 (03.03.87); original claims 1-19 replaced by amended claims 1-19 (4 pages)] 1. A printing assembly (10) comprising a rigid cylinder (12), a plurality of inking rolls (18) and a clip mechanism (26) for clipping said inking rolls (18) to said cylinder (12) to facilitate the attachment, removal and replacement of said inking rolls (18) individually. 2. The printing assembly of claim 1 wherein said rigid cylinder (12) includes a first rigid plate (14) secured to a first end of said cylinder (12) and a second rigid plate (14) secured to a second end of said cylinder 12, each of said plates (14) including a central hole (11) and a plurality of holes (16) in the periphery thereof for receiving the ends (21) of said inking rolls (18) and further comprising a locking mechanism (29) cooperable with said clip mechanism (26) for holding said inking rolls (18) on said clip mechanism (26). 3. The printing assembly of claim 2, wherein said cylinder (12), plates (14), clip mechanism (26) and locking mechanism (29) are made from materials selected from the group comprising aluminum, steel, hard vinyl, hard phenolics. hard plastics, hard rubber, polymer blends and composites thereof. 4. The printing assembly of claim 2 wherein said clip mechanism (26 " ) and locking mechanism (29) are positioned for gripping an exterior surface of said inking rolls (18). 5 . An inking rol l ( 18 ) compr is ing a core (20) of a hard porous material, and a cover member (22) of an ink resistant material substantially surrounding said core (20), said cover member (22) defining a longitudinal gap extending between the ends (21) of the inking roll (18) for exteriorly exposing a longitudinal strip (24) of said core (20). 6. The inking roll (18) of claim 5 wherein said inking roll (18) has a diameter of about 1/4 inch and a length of about six inches, and said cover member (22) has a thickness of about 1/8 the diameter of the inking roll 18. 7. The inking roll (18) of claim 5 wherein said cover member (22) covers about 85% of said core (20), and said strip (24) comprises about 15% of the surface area of said inking roll (18). 8. The inking roll (18) of claim 5 wherein said hard ink-resistant material of cover member (22) is selected from the group comprising aluminum, steel, hard vinyl, hard phenolics. hard plastics, hard rubber, polymer blends and composites thereof, and said hard porous polymer material from which said core (20) is ma5* is a sintered blend of thermoplastic and thermosetting materials. 9. The inking roll of claim 8. wherein said thermoplastic and thermosetting materials are a blend of vinyl, polyethylene and phenolic materials. 10. A method of making an inking roll (18) comprising providing a cover member (22) of an ink resistant material having a generally hollow interior, filling said hollow interior with a polymeric material (20) capable of yielding a hard porous material upon cu ing, curing said polymeric material (20) in said cover member (22) to cure said polymeric material into said hard porous material, and, removing a portion of said cover member to exteriorly expose a portion (24) of said hard porous material. 11. The method of claim 10 wherein the step of filling said hollow interior with a polymeric material comprises the step of metering said polymeric material into said interior in increments 12. The method of claim 11 wherein said step of metering said polymeric material includes the step of applying pressure to said cover member (22) and polymeric material at each said increment. 13. The method of claim 10 wherein the step of providing a cover member (22) comprises the step of providing a cover member (22) having an outside diameter of about 1/4 inch. 14. The method of claim 10 wherein said polymeric material is cured in said cover member (22) at about 305°F for about 1.5 hours. 15. The method of claim 10 wherein the step of providing said cover member (22) comprises the step of providing a cover member having a thickness of about 1/8 the diameter of said inking roll (18). 16. The method of claim 10 wherein the step of removing a portion of said cover member (22) comprises the step of milling about 15% of said cover member (22) to - expose a straight strip (24) of said hard porous material parallel to the longitudinal axis (34) of said inking roll (18). 17. The method of claim 10 wherein the step of removing a portion of said cover member (22) comprises the step of removing a strip of said cover member (22) to expose a straight strip (24) of said hard porous material parallel to the longitudinal axis (34) of said roll. 18. The method of claim 10 wherein the step of providing a cover member (22) comprises the step of providing a cover member (22) composed of a material selected from the group consisting of metallic, phenolic, hard plastic, and polymer blend materials. 19. The method of claim 10 wherein the steps of filling said hollow interior with a polymer material (20) comprises the step of filling said interior with a blend of thermoplastic and thermosetting materials, and said step of curing said polymeric material (20) comprises the step of sintering said blend of thermoplastic and thermosetting materials into said hard porous material.

Inventors: HAREN DOYLE V, WILEY LAWRENCE V, HAREN, DOYLE, V., WILEY, LAWRENCE, V.
Applicants: DAYCO CORP, DAYCO CORPORATION
Application year: 1986
Main classification: B29C31
IPC codes: B29C70, B41F31