Title:
APPARATUS FOR REMOVING FOREIGN PARTICLES FROM A LITHOGRAPHIC PRESS
United States Patent 3822642


Abstract:
A pickup blade of plastic material is slidably mounted for longitudinal movement in a block which is pivotally mounted to a lithographic press frame. An actuating means is operable from a position where an operator can view the finished printed product coming from the press. The actuating means pivots the block to bring the pickup blade into contact with an entire longitudinal edge of a lithographic plate cylinder to pick up foreign particles or to dislodge them sufficiently so that they will be picked up by other existing rollers and removed from the printing surface. The pickup blade can be slid longitudinally off the block to position clear of the press and can then be replaced with a new blade or cleaned and returned to position in the block. This can be done without stopping the press and without inserting the operator's fingers into dangerous positions during operation of the press. In order to obtain rigidity of the support of the blade across the entire longitudinal edge of the plate cylinder, the blade and block can be mounted on a relatively thick walled cylindrical tube which is mounted to the press frame to rotate about its central longitudinal axis.



Inventors:
GRINDELAND G
Application Number:
05/275281
Publication Date:
07/09/1974
Filing Date:
07/26/1972
Assignee:
GRINDELAND G,US
Primary Class:
Other Classes:
15/256.51, 101/169, 118/104
International Classes:
B41F35/02; (IPC1-7): B41F35/00
Field of Search:
101/423-425,156,157,168,169,162,164,165 118
View Patent Images:
US Patent References:
3660863CLEANING APPARATUS1972-05-09Gerbasi
3327341Doctor blade for calender roll1967-06-27Kuehn
3144826Device for removing hickies from printing plates1964-08-18Lang et al.
3026796Doctor blade assembly1962-03-27Crawford
2534320Apparatus for coating paper1950-12-19Taylor
2188114Surface cleaner1940-01-23Hubbard
1993352Doctor blade structure1935-03-05Schwartz
1509612Knife for ink mills1924-09-23Ruckriegec



Primary Examiner:
Coughenour, Clyde I.
Attorney, Agent or Firm:
Dorsey, Marquart, Windhorst, West & Halladay
Parent Case Data:


BACKGROUND OF THE INVENTION

This invention is a continuation-in-part of my application, Ser. No. 167,920, filed Aug. 2, 1971 for APPARATUS FOR REMOVING FOREIGN PARTICLES FROM A LITHOGRAPHIC PRESS, now abandoned.
Claims:
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows

1. For use with a lithographic printing press capable of producing printed work having a press frame and a rotating plate cylinder for supporting a lithographic plate, apparatus for removing foreign particles from said lithographic plate, which comprises:

2. The apparatus of claim 1 wherein said pickup blade is slidably mounted with respect to said rigid cylindrical tube.

3. The apparatus of claim 1 wherein said pickup blade is made of a plastic material.

4. The apparatus of claim 3 wherein said pickup blade is made of plastic material selected from the group consisting of polyethylene, polytetrafluorethylene and neoprene.

5. The apparatus of claim 2 wherein said pickup blade is made of a plastic material.

6. The apparatus of claim 5 wherein said pickup blade is made of plastic material selected from the group consisting of polyethylene, polytetrafluorethylene and neoprene.

Description:
DESCRIPTION OF THE PRIOR ART

The removal of foreign particles, commonly called "hickies," from the lithographic plate of a lithographic press has long been a problem. The problem is two-fold. First, the particles must be removed to achieve perfectly printed products. Second, the means and method for removing the particles should not entail even an opportunity for the operator to reach into dangerous areas while the press is running. This problem has persisted in spite of the issuance of patents designed to alleviate it. For example, it has been suggested to pivotally mount a relatively narrow scraper blade on a shaft in parallel spaced relationship from the surface of the plate cylinder, to provide structure which allows longitudinal movement of the blade along the shaft and to provide for a handle so that the plate can be mechanically brought into contact with the plate cylinder at various places along the cylinder to attempt to remove deleterious materials. See U.S. Pat. No. 3,144,826. Unfortunately, this calls for an operator to observe the presence of a blemish on the finished work high above the output end of the press and to have him or another operator move the scraper blade longitudinally into position in radial alignment with the blemish on the plate cylinder and then to manually activate the device to cause the scraper blade to come in contact with the plate cylinder. This longitudinal movement to obtain radial alignment with the "hickey" and the necessity to mechanically pivot the scraper blade into the plate cylinder is dangerous to the operator and has presented such other difficulties that the structure has not been widely accepted.

A further difficulty with the short scraper blade structure is that the wearing or temporary effect which the scraper blade has on the finished printing due to its contact with only part of the lithographic plate tends to cause bands of non-uniform printing to result on the finished product.

Other uses of scrapers on limited areas of lithographic plates have been proposed. For example, U.S. Pat. No. 3,108,539 utilizes scrapers to remove ink from first and second feed cylinders to prevent migration of one color of ink into the area of another color of ink. Here the effect is clearly to operate on narrow bands of rotating cylinders only, which is just exactly the opposite effect needed to successfully remove hickies from the entire surface of a plate cylinder during operation of a lithographic press.

It has been proposed to position a relatively narrow wiper member against the plate cylinder and to cause this member to move back and forth across the face of the plate cylinder constantly during operation of the press to attempt to disturb hickies to the end that they can be picked up later in their movement with the plate cylinder by the inking rolls or other rolls and thus be removed from the plate cylinder. See U.S. Pat. No. 3,252,416. This structure has also proved unsatisfactory and has not been generally adopted since the patent issued. This patent, however, provides an excellent discussion of the danger and problem of removing hickies in column 1 and in column 2 to line 63.

As pointed out in U.S. Pat. No. 3,252,416, referred to above, rotating leather rollers extend the full length of the plate cylinder have been proposed, but these rollers and other similar rollers tend to quickly fill with hickies and the time lost in shut-down for the replacing of the rollers is considerable.

Positively driven rollers rotating at speeds different from that of the plate cylinder in which they are in contact have also been suggested. See U.S. Pat. No. 3,467,008. This method calls for disturbing the hickey to cause it to be picked up by the positively rotating roller to be carried into the other rollers of the fluid supply system where the rollers can be removed "from the collection point in a single operation after a given printing run of the press has been completed." Column 3 of U.S. Pat. No. 3,467,008, lines 71 through 73. It is to be noted that no means is provided for cleaning the accumulated hickies from the machine during operation of the press.

In the standard printing art, various devices have been suggested for scraping or cleaning one or more drums by positioning scraper blades across the entire surface of such drums. See U.S. Pat. Nos. 3,194,156; 3,468,248; 3,327,341; 3,026,796; and 3,593,663. These patents have to do with bringing blades in contact with rollers generally in the printing art, but are believed to be not pertinent to the problem of disturbing the surface of a lithographic plate which is actually performing the offset print out process in such a manner as to pick up or at least to loosen "hickies" which are present thereon. In general, these patents are no more pertinent than would be the prior art structure of an old-fashioned "steamroller" to scrape the tar and road surface particles from the roller in the process of compacting a roadway.

Use of a pad across the entire surface of the offset cylinder has been suggested, and it has been suggested that moisture be added to this pad to prevent a change of condition in the offset plate, either drying it out or leaving it too wet. See U.S. Pat. No. 3,094,068. The problem of a pad filling up with hickies during a run and thereby necessitating the shutdown of the press during the runs, however, is a serious one and has prevented this structure from being widely accepted.

In order to provide uniformity of operation across the entire surface of the plate cylinder, it is essential that the axis upon which the pickup blade rotates is exactly parallel to the outer surface of the lithographic plate as supported on the plate cylinder. Likewise, it is important that the exactly correct relationship between the pickup blade and the lithographic plate, supported on its cylinder, be established and maintained in spite of the wearing of the pickup blade, and any changes in the size of replacement pickup blades.

SUMMARY OF THE INVENTION

The apparatus of the present invention includes a plastic pickup blade which can be brought in contact with the entire longitudinal edge of a rotating lithographic plate running on a plate cylinder. This blade has a sharply defined rather blunt edge defined by two outside plane surfaces intersecting at a right angle or an acute angle. This blade is mounted in a slot provided in a blade block which is pivotally mounted to permanent frame portions of the lithographic press to move between a first position in which the edged pickup blade is in contact with the plate cylinder to disturb hickies and remove them therefrom and to a second position in which the edged blade will be in clearing relation to the plate cylinder. In many installations, the slot and blade will be longitudinally or transversely in clearing relation to the frame of the press. This will allow the blade to be removed from the block and replaced or cleaned to remove hickies therefrom and returned to the drum without disassembly of any other part of the press or the apparatus for removing hickies. The blade can also be cleaned in place with a solvent-coated cloth when the press is stopped.

A remotely operated power linkage between the frame of the printing press and the block is controlled from a location where an operator can observe the quality of the printing leaving the press, and is operative to move the blade and block between the aforementioned first and second positions as determined by the operator upon observation of the finished work product leaving the press.

In order to insure that there will be no deflection of the edge of the pickup blade out of exact parallel alignment with a longitudinal edge of the lithographic plate on its rotating plate cylinder, the block in which the pickup blade is mounted can be integrally attached to or constituted as a part of a relatively thick walled rigid cylinder which is mounted on bearings at either end of the plate cylinder on the press frame. In order to achieve accurate adjustment of the relationship of the pickup blade to the lithographic plate on the cylinder, these bearings can be mounted for independent movement toward and away from the rotating plate cylinder.

In the drawings:

FIG. 1 is an elevational view of a portion of a lithographic printing press showing a "hickey" pickup blade of a first form of the present invention in contact with a portion of a lithographic plate on a plate cylinder of the press;

FIG. 2 is a fragmentary rear elevational view of a portion of the press of FIG. 1 further showing the relationship of the pickup blade and a block with respect to the lithographic printing plate and plate cylinder;

FIG. 3 is an enlarged fragmentary vertical sectional view taken on the line 3--3 in FIG. 2;

FIG. 4 is a further enlarged transverse sectional view of the pickup blade and block;

FIG. 5 is a fragmentary elevational view of a portion of a lithographic printing press showing a "hickie" pickup blade of a second form of the present invention in contact with a portion of a lithographic plate on a plate cylinder of the press, and showing the supporting and operating apparatus and mechanism for that blade;

FIG. 6 is a sectional view taken on the line 6--6 in FIG. 5; and

FIG. 7 is a vertical sectional view taken on the line 7--7 in FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS:

Offset lithographic presses are widely utilized in the printing field throughout the world and details of construction of such presses are well known. As disclosed in U.S. Pat. No. 3,467,008, for example, lithographic presses can include plate, blanket, impression and transfer cylinders of essentially the same size and rotating at the same speed relative to each other from a common drive source. Other rollers constitute dampening and inking supply systems. For example, as shown in that patent, a plate cylinder 2 is contacted by water applying rollers 21 and 22, inking rollers 42 and 43, and secondary inking rollers 48 and 49. Similar rollers will, of course, be present on the lithographic presses incorporating the invention disclosed herein, but have been omitted from the drawings for the sake of clarity.

As seen in FIGS. 1 through 4, in a first form of the invention, a lithographic press 10 includes a press frame 12 having upright side frame members 14 and 16 tied together by transverse tie rods 18, one of which is shown. A plate cylinder 20 is rotatably mounted in the side frame members as at 22, and has a lithographic plate 24 affixed thereto in any usual or preferred manner. During operation of the press, the plate cylinder will be rotated in a counter-clockwise direction, as seen by the arrow 26 in FIG. 3.

As shown, a pair of generally upright support arms 28,28 are fixedly clamped on the transverse tie rod 18 as at 30, and a pickup blade mounting block 32 is pivotally supported between the arms 28,28 through the instrumentality of pivot pins or bearings 34 which extend inwardly from arms 28,28 and which can be adjusted to achieve precise positioning of the block 32. Block ears 36 extend downwardly from the block and each is pivotally connected to an actuating arm or piston rod 38 which extends upwardly from an air-operated piston-cylinder motor 40 likewise fixedly mounted with respect to the tie rod 18 as at 42.

An edged pickup blade 44, made of polyethlene, polytetrafluoroethylene (TFE), neoprene or some other suitable material, is mounted for longitudinal movement with respect to the blade block 32 in direction in alignment with the axis of the plate cylinder, and is provided with a working edge 54. The blade 44 is also provided with a T-bar extension 46 which is received into a T-slot 48 provided in the blade mounting block 32.

It is to be noted that the side frame members 14 and 16 are provided with outwardly extending brackets 50,50 to support other equipment on the press, but that these brackets are each provided with an opening 52 therethrough. This allows access to either end of the pickup blade 44, so that when the blade is situated in spaced relationship to the lithographic plate 24, it can be pushed from one end to slide with respect to the block 32 and extend out through the other end sufficiently so that it can safely be grasped and pulled from the block when it is necessary or desirable to clean it or to replace it because it has become worn on its edge 54. By using a push rod from one end to move the blade far enough beyond the side frame member at the other end, removal and replacement of the blade can be accomplished. Thus there is no chance of accident and injury to the operator.

In operation, air lines 56,56 from a source of pressure (not shown) extend to and through a control switch 58 to each cylinder 40 as shown schematically in FIG. 3. This switch is located in actual practice within easy reach of an operator positioned to watch the finished work come off of the press. When the operator detects the presence of foreign particles on the lithographic plate 24, as evidenced by imperfections in the finished work, he activates the control switch to cause the air cylinder 40, acting through control arm 38 on block ears 36, to rotate the block about the pivot pins or bearings 34 to cause the working edge 54 of pickup blade 44 to come into contact with the lithographic plate 24, to pick up the foreign particles on the plate, or to dislodge them in such a manner that they will be picked up by subsequent rollers and carried from roller to roller away from the plate cylinder in a manner well known in the art. It is helpful that the blade used has at least some slight electrostatic tendencies so that the particles will tend to adhere thereto. Good results can be obtained when the pickup blade of the invention contacts the lithographic plate either just before or just after the plate is contacted by the dampening rollers.

When the operator has accomplished his result in clearing the plate, he releases the control switch 58, and the piston rod arms 38 relax under an internal bias to cause the pickup blade 44 and mounting block 32 to take the position as seen in dotted lines in FIG. 3. The block is mounted to then be in clearing alignment with the frame so the blade can be removed from the block in the manner aforesaid.

Good results can be obtained when this angle defined by the planes intersecting to form working edge 54 is as great as 90° as long as the angle between the blade wall surface opposite the direction toward which the plate cylinder is rotating and a plane tangent to the cylinder, extending away from the direction of cylinder rotation and including the working edge of the blade is 90° or less.

Referring now to the second form of the invention as seen in FIGS. 5 through 7, a lithographic press 110 includes a press frame 112 having parallel spaced apart upright side frame members 114 and 116. These side frame members are tied together by transverse tie rods 118, one of which is shown. A plate cylinder 120 is rotatably mounted in the side frame members and has a lithographic plate 124 affixed thereto in any usual or preferred manner. During operation of the press, the plate cylinder will be rotated in a counter-clockwise direction, as seen by arrow 126 in FIG. 5.

As shown, a pickup blade assembly 131 includes a pair of mounting arms 128 which are fixedly clamped on the transverse tie rod 118 as at 130. In order to insure complete rigidity and accurate positioning of the parts, a pickup blade 144 is mounted in a T-slot 148 provided in a pickup blade mounting block 132 which in turn is integrally connected as at 135 to a rigid thick walled cylindrical tube 137. Extending from opposite ends of the tube 137 are stub shafts 139,139. Collars 141,141 are also carried on these stub shafts. The tube 137 and collars 141,141 are keyed to the stub shafts 139,139 as at 143.

As shown, the outer races of ball bearings 145,145 are fixedly mounted in the outer ends of collars 141,141 while the inner races are fixedly mounted on mounting studs 147,147, each of which consist of three axially aligned cylindrical portions, the middle portion being of greater diameter than the two end portions.

Mounting arms 128 are each provided with a mounting stud receiving slot 149. A threaded positioning rod 151, controlled by a knurled hand knob 153, impinges on the outer end of mounting stud 147 when it is situated in slot 149 to positively set the relative position of the mounting studs, and hence the entire pickup assembly and including particularly the mounting blade, with respect to the outer periphery of the plate cylinder and of the lithographic plate 124.

At one end of the pickup blade assembly 131, an air operated piston-cylinder motor 140 is pivotally mounted on a bracket 155 which itself is integrally mounted on the bottom side of one of the mounting arms 128. The collar 141 at that end of the pickup blade assembly has an integral operating finger 157 extending outwardly therefrom, and the piston of the motor 140 is pivotally mounted thereto, as best seen in FIG. 7.

In operation, an air line 156 from a source of pressure (not shown) extends to and through a control switch 158 to the motor 140, as shown schematically in FIG. 6. As in the case with the first form of the invention, this switch is located within easy reach of an operator who is positioned to watch the finished work come off of the press. As explained in connection with the first form of the invention, the operator will activate the control switch to cause the piston-cylinder motor 140, acting through finger 157 to rotate the pickup blade assembly 131 to cause the working edge 154 of the pickup blade 144 to come into contact with lithographic plate 124, thus to pick up the foreign particles from the plate onto the blade, or to dislodge these particles in such a manner that they will be picked up by subsequent rollers and carried from roller to roller away from the plate cylinder.

When the operator has accomplished his result in clearing the lithographic plate, he releases the control switch 158, and the piston rod moves downwardly as seen in FIG. 7 under the bias of spring 159, thus removing the pickup blade from contact with the lithographic plate 24.

It is to be understood that by using the knurled knobs 153 acting through threaded positioning rods 151, the exact parallel positioning of the pickup blade assembly and consequently of a pickup blade working edge 154 can be attained and maintained.

Likewise, it is to be understood that the rigidity of the thick walled cylindrical tube 137 insures that there will be no "sag" in the working edge 154 of the pickup blade 144 between the ball bearings 145,145.

Should the pickup blade become worn, it can either be replaced as explained in connection with the first form of the invention, or the proper alignment of it with respect to the surface of the lithographic plate 124 can be re-established by use of the threaded positioning rods 151,151.