Low inertia ink ductor

Abstract

 A printing press ink ductor roll rotates about its axis and moves between an ink fountain roll (65) to pick up ink on its outer surface from the fountain roll and an ink train roll to deliver ink from its outer surface to the ink train roll. The ductor roll comprises opposite journals (11, 12) for mounting the ductor roll for rotation about its axis, a tube (14) attached at its opposite ends to said journals. The tube is a composite comprising 30 to 70% by weight of graphite fibers and 70 to 30% by weight of a thermoplastic or thermosetting resin.

Description

Background and Summary of the Invention

[0001] The present invention relates to an ink ductor roll which transfers ink from a printing press ink fountain roll to an ink train roll of the printing press.

[0002] A printing press includes an inker. An inker typically includes a fountain roll, ink train rolls, and a ductor roll which rotates about its own axis and moves between a position in ink transferring contact with the fountain roll and a position out of ink transferring contact with the fountain roll and in ink transferring contact with an ink train roll to transfer ink from the fountain roll to the ink train roll. Typically, the ductor roll is not driven and rotates about its axis at a speed dependent upon the speed of the roll with which it is in contact. The ductor roll turns about its own axis at a relatively low peripheral speed while the ductor roll is in contact with and receives ink from the fountain roll. The ductor roll, after receiving ink from the fountain roll, moves out of contact with the fountain roll and into contact with the first ink receiving roll in the ink train. During this movement, the ductor roll either continues to rotate at a low peripheral speed or decelerates to a standstill as a result of friction in the ductor roll bearings. When the ductor roll contacts the first ink receiving roll in the ink train, the ink train roll transfers a significant amount of rotational energy to the ductor roll to bring it up to the relatively high peripheral speed of the ink train roll. The ink train roll is normally driven by the press drive. Thus, the ductor roll, when it comes into contact with the first ink receiving roll in the ink train, applies a torsional load on the press drive. The torsional load which is applied by the ductor roll to the ink train roll and to the press drive is a function of the ductor roll inertia and its rotational speed and direction when it contacts the first ink receiving roll in the ink train. This torsional load minimizes the speed at which the press can be driven since the higher the press speed, the higher the torsional load.

[0003] U.S. Patent No. 3,688,696 attempts to solve this problem by driving the ductor roll with a separate motor up to the speed of the first ink receiving roll in the ink train while the ductor roll is traversing the space between the fountain roll and the first ink receiving roll. In this way, the ductor roll is accelerated independently of the printing press drive before the ductor roll contacts the ink receiving roll in the ink train and, therefore, torsional loads on the press drive are minimized. However, obviously this involves complication in the mechanism and cost in providing the drive for the ductor roll.

[0004] The present invention is directed to a solution of the problem by the use of a low inertia ductor roll. Specifically, the ductor roll of the present invention has a strength which is equivalent to that of known ductor rolls, which are primarily made of steel, but which has a substantially lower weight and thus lower inertia. The ductor roll of the present invention enables the press speed to be increased by approximately 50% due to the minimization of the torsional loads applied to the press drive by the ductor roll. Further, due to the stiffness of the ductor roll of the present invention, there is no detrimental affect on the transfer of ink from the fountain roll to the first roll of the ink train and there is no loss of ink control due to a loss of ductor roll stiffness.

[0005] The ductor roll of the present invention includes a member which rotates and has an ink receptive covering thereon. The member is made of a composite which includes fibers and a resin. The fibers may be boron fibers, graphite fibers, aramid fibers and/or glass fibers. The resin may be thermoplastic or thermosetting.

[0006] In one specific embodiment of the present invention, the ductor roll comprises opposite metal journals which mount the ductor roll for rotation about its own axis in the mechanism which moves the ductor roll between the fountain roll and the first ink receiving roll of the ink train. A tube extends between the journals and is fixedly attached at its opposite ends to the journals. An ink receptive rubber covering is fixedly secured to the outer diameter of the tube and contacts the ink film on the fountain roll to receive ink and contacts the first ink receiving roll of the ink train to deliver ink to that roll of the ink train. The tube is made of a graphite epoxy composite which gives the tube sufficient strength (stiffness), equivalent to that of steel, but which is of substantially lower weight than steel and thus the ductor roll inertia is extremely low. Specifically, in one embodiment the modulus of elasticity of the material of the tube times the moment of inertia of the tube equals 5.5 × 10⁷ lb. in.² to 6.4 × 10⁷ lb in.². This results in reducing the torsional loads applied to the press drive by the ductor roll when the ductor roll contacts the first ink receiving roll in the ink train. This enables press speed to be increased substantially.

[0007] The ductor roll of the present invention is of such low inertia that the ductor roll can be used in an inker where the fountain roll rotates about its axis in one direction and the first roll of the ink train rotates in the same direction about its axis. As a result, the ductor roll rotates in one direction about its axis when in contact with the ink fountain roll and rotates in the reverse direction about its axis when in contact with the first ink receiving roll of the ink train. Such inkers are called "bucking" type inkers and the ductor roll direction of rotation about its axis must be reversed during normal operation. This type of inker arrangement results in a substantial torsional loading of the drive train when the ductor roll comes into contact with the first ink receiving roll of the ink train.

[0008] Accordingly, a principle object of the present invention is to provide a low inertia ductor roll for an inker of a printing press which, as a result of its low inertia, applies a minimum of torsional loading to the press drive when the ductor roll comes into contact with the first ink receiving roll of the ink train. This is accomplished, in accordance with the present invention, without affecting the ink transfer capability of the ductor roll detrimentally and, specifically, by maintaining the stiffness of the roll the equivalent of steel even though it is of substantially lighter weight.

Description of the Drawings

[0009] Further objects and advantages of the present invention will be apparent to those skilled in the art to which the present invention relates from the following detailed description of a preferred embodiment made with reference to the accompanying drawings forming a part of this specification and in which:

Fig. 1 is a view partly in section of an ink ductor roll embodying the present invention;

Fig. 2 is a view of a part of the ink ductor roll shown in Fig. 1;

Fig. 3 is a cross sectional view of a part of the ink ductor roll showing the material of the part;

Fig. 4 is a schematic view showing the mechanism for moving the ductor roll; and

Fig. 5 is a schematic view of a printing press embodying the ink ductor roll of Fig. 1.

Description of Preferred Embodiment

[0010] As noted above, the present invention relates to an ink ductor roll which rotates about its own axis and moves between a first position in contact with an ink fountain roll to pick up ink on its outer peripheral surface from the ink fountain roll and a second position in engagement with a first ink receiving roll of an ink train to deliver ink from its outer peripheral surface to the first ink receiving roll of the ink train. The ductor roll of the present invention has low inertia and thus does not apply a high torsional load to the printing press drive when it comes into contact with the ink receiving roll of the ink train which is driven by the press drive.

[0011] Fig. 1 illustrates a ductor roll 10 embodying the present invention. The ductor roll 10 includes a pair of opposite steel one-piece journals 11, 12 located at opposite ends of the roll. The journals 11, 12 support the ductor roll for rotation about the axis 13 of the ductor roll.

[0012] The ductor roll 10 further includes a tube 14 which is fixedly attached at its opposite ends to the journals 11, 12 and forms the body of the ductor roll 10. An ink receptive covering 15 is fixedly secured to the outer diameter of the tube 14. The journals 11, 12 are of identical construction and therefore only the journal 12 will be described in detail.

[0013] The journal 12 is shown in Fig. 2 and includes a hub portion 20 and a sleeve portion 21. The sleeve portion 21 has an outer diameter which corresponds to the inner diameter of the tube 14. The outer diameter of the sleeve portion 21 projects into the inner diameter of the tube 14 and a suitable adhesive is utilized between the outer diameter of the sleeve portion 21 and the inner diameter of the tube 14 to adhesively secure the tube 14 to the sleeve portion 21 of the journal 12.

[0014] The sleeve portion 21 is a cylindrical relatively thin metal portion of the journal 12 and is integrally connected to the hub portion 20 by a flange portion 24. The flange portion 24 has an outer circular peripheral surface 25 which is of a diameter slightly larger than the outer diameter of the sleeve portion 21. In view of the difference in the outer diameters, there is a step or shoulder 27 on the outer diameter of the journal 12. The inner diameter of the tube 14 has a similar mating shoulder 28, as shown in Fig. 1.

[0015] The hub portion 20 has, at its right end as shown in Fig. 2, a relatively small diameter portion designated 30 for receiving a bearing 31 which supports the ductor roll 10 for rotation about its own axis 13.

[0016] The flange portion 24 and the hub portion 20 have a frustoconical recess 33 centrally located in the hub 12. The recess 33 communicates with an axial passage 35 in the hub portion 20. The axial passage 35 extends from the recess 33 through the end surface 37 of the ductor roll. The purpose of the recess 33 and passage 35 is twofold. One purpose is that they provide a weight reduction and secondly they permit air to escape from the interior of the ductor roll during the assembly of the various parts of the ductor roll.

[0017] The bearing 30 which supports the ductor roll for rotation about it own axis is secured on the ductor roll journal between a washer 40 and a shoulder 41 on the journal 12. The washer 40 is held in position by a suitable fastener, which is shown as a flathead screw 43 which is threaded into a threaded portion of the passage 35.

[0018] The tube 14 is made of a fiber resin composite. The fibers may be boron fibers, graphite fibers, aramid fibers or glass fibers. The resin may be thermosetting or thermoplastic. Preferably, graphite fibers are used.

[0019] Specifically, the tube 14 has a fiberglass layer 45 (see Fig. 3) forming the inner diameter of the tube 14 which is adhesively secured to the sleeve portions 21 of the journals 11, 12. The fiberglass interior layer 45 is formed integrally with a graphite fiber epoxy composite 46. As noted above, other fibers could be used. The fibers extend throughout the layer 46 of the tube. The fibers are embedded in the epoxy. In one embodiment, the modulus of elasticity of the material of the tube times the moment of inertia of the tube should be in the range of 5.8 × 10⁷ lb in.². to 6.4 × 10⁷ lb. in.². This results in the overall weight and inertia of the ductor roll being minimized. In one specific embodiment, the weight of the tube 14 was reduced from 36 lbs. for steel to 10.6 lbs. without sacrificing the stiffness of the roll and, therefore, providing the equivalent strength to steel. The lower inertia and lower weight provides substantial advantages.

[0020] The ink ductor roll tube 14 is preferably fabricated by laminating the inner fiberglass layer 45 optionally treated with a resin and/or coupling agent, with the outer layer 46 comprising the composite of one or more fibers in a matrix of one or more thermoplastic or thermosetting resins such that the tube 14 will be useful at temperatures up to about 300°C and will have the requisite physical properties to operate at high roller surface speeds at least about 2500 feet per minute.

[0021] The fiber should comprise a major amount of boron, graphite, aramid or glass fibers and a minor amount of any other fibers. The fibers are fabricated into the composite by the usual techniques and preferably are treated with a coupling agent, preferably a silane coupling agent. The fibers typically are in the form of strands which extend continuously through the tube 14. The strands or fibers are typically wound onto a mandrel and sprayed with the resin to form the composite.

[0022] The fibers together with one or more thermoplastic and/or thermosetting resins constitute the outer layer composite 46 which overlays the inner fiberglass base layer 45 which also optionally is treated with a resin and/or coupling agent. Suitable resins include, for example, epoxy resins, polyesters, polyimides, polyethylenes, and polytetrafluoroethylenes.

[0023] When the resin is a thermosetting resin, it is preferred to use an epoxy resin or a polyester. Preferred epoxy resins are bisphenol A epoxies and Novolac epoxies. Most preferred epoxy resins are the glycidyl esters of hydroxyphenol, hydroxycylcloalkanes, particularly bis (hydroxycyclohexane) and derivatives resulting from the reduction of bisphenol A hydroxides, and 4 4-diamino­diphenyl methanes.

[0024] Useful polyesters include saturated and unsaturated polyesters formed by the reaction of dibasic acids with various glycols, such as proylene glycol, ethylene glycol, and diethylene glycol. Most preferred polyesters are maleic and/or phthalic esters derived from maleic anhydride and phthalic anhydride. Optionally, a minor portion of the anhydride can be substituted with alkyldiacids, such as adipic acid.

[0025] The composite layer 46 consists mainly of two phases comprising 30 to 70% resin matrix and 70 to 30% carbon/graphite fibers wherein the carbon/graphite fibers constitute at least 50% and preferably greater than 80% of the total filament/fiber portion. It is preferred to pretreat the fibers with an appropriate coupling agent, preferably a silane, prior to compounding with the resin matrix.

[0026] The ink covering 15 is secured to the outer periphery of the tube 14 by a suitable adhesive. The ink covering 15 may be made of any suitable material, such as a conventional hard rubber covering which is known and presently used for ink ductor rolls.

[0027] The ductor roll 10, when used in a printing press, substantially reduces torsional loads on the printing press drive and thereby enables the speed of the printing press to be increased. Figs. 4 and 5 illustrate the ductor roll schematically in a printing press. Fig. 4 shows the ductor roll 10 mounted on a pivoting arm 60. Specifically, the ductor roll 10 is mounted at one end of the arm 60. The other end of the arm 60 carries a cam follower 61 which engages a cam 62. Rotation of the cam 62 causes the ductor roll 10 to move between two positions. In one position, the ductor roll is, as illustrated in Fig. 4, in ink receiving contact with a fountain roll 65 of the printing press. In a second position, the ductor roll is in contact with a vibrator roll 66 which is the first ink receiving roll in the ink train of the printing press.

[0028] Fig. 5 illustrates a printing press 80 embodying the present invention. The press 80 is a blanket-to-blanket offset lithographic printing press. Specifically, the printing press includes a pair of blanket cylinders 81, 82 which print on web material which moves through the nip defined by the blanket cylinders. The blanket cylinders 81, 82 cooperate with plate cylinders 83, 84, respectively. The plate cylinders 83, 84 carry the printing plates which carry the image to be printed on the web material.

[0029] The plate cylinders 83, 84 have associated dampeners 87, 88 which apply dampening fluid to the plates. Also, the plate cylinders have associated inkers 91, 92. The inkers 91, 92 include a train of ink rolls which deliver ink to the plate on the plate cylinders 83, 84 and the first ink receiving roll in each of the inkers is the vibrator roll 66. A ductor roll 10 in accordance with the present invention is mounted to deliver ink from the fountain roll 65 on each of the inkers to the vibrator roll 66.

[0030] The vibrator roll 66 and the fountain rolls 65 in each of the inkers 91, 92 rotate about their own axes in the direction indicated by the arrows in Fig. 5. The ductor roll 10 is a nondriven roll and rotates at the speed and direction of the roll with which it comes into contact. When the ductor roll 10 is in contact with the fountain roll 65, it rotates in a clockwise direction about its axis 13, as shown in Fig. 5. When the ductor roll 10 for the upper printing unit moves into contact with the upper unit vibrator roll 66, it rotates in a clockwise direction about its axis as shown in Fig. 5, and when the ductor roll 10 for the lower printing unit moves into contact with the lower unit vibrator roll 66, it rotates in a counterclockwise direction about its axis. Thus, the ductor roll 10 of the lower printing unit reverses its direction of rotation during operation of the printing press and the ductor roll 10 of the upper printing unit accelerates and decelerates. When the ductor roll 10 contacts the vibrator roll 66, the ductor roll 10 places a torsional load on the printing press drive. The ductor roll 10 of the present invention substantially reduces the load applied to the printing press drive because of its substantially lower weight than known ductor rolls. In fact, the ductor roll of the present invention has enabled the printing press to be driven at substantially increased speeds. For example, increasing the speed of the press from 1600 feet of web per minute to 2500 feet of web per minute. This is a substantial increase in the speed of the press simply due to the use of the ductor roll of the present invention.

[0031] The invention has been described above referring to a preferred and illustrated embodiment. Alterations and modifications may occur to those skilled in the art upon reading the specification. For example, the invention is applicable to ductor rolls of a dead shaft construction and ductor rolls where the journals are of a material other than metal. It is intended to include all such modifications and alterations within the scope of the appended claims or the equivalent thereof.

Claims

1. A printing press ink ductor roll which rotates about its axis and moves between an ink fountain roll to pick up ink on its outer surface from the fountain roll and an ink train roll to deliver ink from its outer surface to the ink train roll, said ductor roll comprising a member having an ink receptive coating thereon, said member comprising a composite comprising 30 to 70% by weight of fibers and 70 to 30% by weight of a thermoplastic or thermosetting resin, said fibers selected from the group consisting of boron fibers, graphite fibers, aramid fibers and glass fibers.

2. The ink ductor roll of claim 1 wherein a major portion of the fibers are graphite fibers.

3. The ink ductor roll of claim 2 wherein the resin is a thermosetting resin.

4. The ink ductor roll of claim 2 wherein said tube comprises graphite fibers and said resin is an epoxy resin.

5. The ink ductor roll of claim 4 wherein the epoxy resin is selected from the group consisting of bisphenol A epoxides, Novolac epoxies, glycidyl ethers of hydroxyphen­ ylethers, and glyciclyl ethers of 4 4-diaminodiphenyl methane.

6. The ink ductor roll of claim 4 wherein at least a minor portion of the epoxy resin is a cycloaliphatic epoxy resin.

7. A printing press ink ductor roll which rotates about its axis and moves between an ink fountain roll to pick up ink on its outer surface from the fountain roll and an ink train roll to deliver ink from its outer surface to the ink train roll, said ductor roll comprising opposite journals for mounting the ductor roll for rotation about its axis, a tube attached at its opposite ends to said journals, said tube being a composite comprising 30 to 70% by weight of fibers and 70 to 30% by weight of a thermo­plastic or thermosetting resin, said fibers selected from the group consisting of boron fibers, graphite fibers, aramid fibers and glass fibers.

8. The ink ductor roll of claim 7 wherein a major portion of the fibers are graphite fibers.

9. The ink ductor roll of claim 8 wherein the resin is a thermosetting resin.

10. The ink ductor roll of claim 8 wherein said tube comprises graphite fibers and said resin is an epoxy resin.

11. The ink ductor roll of claim 10 wherein the epoxy resin is selected from the group consisting of bisphenol A epoxides, Novolac epoxies, glycidyl ethers of hydroxyphen­ylethers, and glyciclyl ethers of 4 4-diaminodiphenyl methane.

12. The ink ductor roll of claim 10 wherein at least a minor portion of the epoxy resin is a cycloaliphatic epoxy resin.

13. A printing press ink ductor roll which rotates about its axis and moves between an ink fountain roll to pick up ink on its outer surface from the fountain roll and an ink train roll to deliver ink from its outer surface to the ink train roll, said ductor roll comprising opposite metal journals for mounting the ductor roll for rotation about its axis, a tube attached at its opposite ends to said journals, said tube being made of a graphite fiber and epoxy resin composite, and an ink receptive rubber covering secured to the outer diameter of said tube.

14. A printing press ink ductor roll as defined in claim 13 wherein each of said journals includes a hub portion and a cylindrical sleeve portion projecting from said hub portion into said tube, adhesive bonding the outer diameter of said sleeve portion to the inner diameter of said tube.

15. A printing press ink ductor roll as defined in claim 14 wherein said hub portion includes an axial passage therethrough.

16. A printing press ink ductor roll as defined in claim 15 wherein said tube includes an outer layer of 30 to 70% by weight graphite fibers and 70 to 30% by weight of an expoxy resin laminated to an inner layer of fiberglass.

Drawing