Apparatus For Fitting Flexible Printing Plates And Rigging To Printing Press Cylinders

Abstract

This printing press includes improved mechanism for clamping the edges of a flexible printing plate adjacent the leading and trailing edges of the saddle of a printing press cylinder. An auxiliary roll mechanism permits the flexible printing plate or rigging sheet to be held smooth and under tension during its installation on the cylinder.

Description

CROSS-REFERENCES

U.S. Pat. application Ser. No. 173,555, filed Aug. 20, 1971, now U.S. Pat. No. 3,762,319, by the same inventors, entitled "Plate Wiping Mechanism for Intaglio Press," discloses an apparatus which may be used on the same press with the present invention.

U.S. Pat. application Ser. No. 188,195, filed Oct. 12, 1971, now U.S. Pat. No. 3,759,177, by the same inventors, entitled "Printing Press With Sheet Inspection Station," discloses another apparatus which may be used on the same press with the present invention.

U.S. Pat. application Ser. No. 195,364, filed Nov. 3, 1971, now U.S. Pat. No. 3,749,330, by the same inventors, entitled "Apparatus for Delivering Sheets Onto A Moving Strip of Material," discloses another apparatus which may be used on the same press with the present invention.

U.S. Pat. application Ser. No. 298,443 filed Oct. 17, 1972, by the same inventors, entitled "Printing Pressure Control Apparatus For Intaglio Press," discloses another apparatus which may be used on the same press with the present invention.

U.S. Pat. application Ser. No. 298,444 filed Oct. 17, 1972 by the same inventors, entitled "Paper Feed Mechanism for Cylinder Press," discloses another apparatus which may be used on the same press with the present invention.

BRIEF SUMMARY OF THE INVENTION

The invention comprises three principal parts, namely:

1. A CLAMP FOR HOLDING THE LEADING EDGE OF A FLEXIBLE PRINTING PLATE OR FLEXIBLE RIGGING ON THE PERIPHERY OF A PRINTING CYLINDER;

2. A MECHANISM FOR MAINTAINING THE PLATE SMOOTHLY ON THE CYLINDER AND UNDER TENSION DURING THE INSTALLATION OF THE PLATE ON THE CYLINDER; AND

3. A MECHANISM FOR CLAMPING THE TRAILING EDGE OF THE PLATE TO THE CYLINDER PERIPHERY.

The mechanism for clamping the leading edge of the plate to the cylinder periphery may be of any suitable conventional construction.

The mechanism for holding the plate smooth and under tension during installation includes an auxiliary roller, a carriage supporting the roller and movable between:

1. A RETRACTED POSITION IN WHICH THE ROLLER IS SPACED FROM BOTH THE PRINTING AND PRESSURE CYLINDERS OF THE PRESS; AND

2. EITHER OF TWO ACTIVE POSITIONS IN WHICH THE ROLLER ENGAGES ONE CYLINDER OR THE OTHER.

The carriage is pivotally supported for movement between these three positions, and provision is made for locking the carriage in any one of the three positions. The carriage includes a pair of spaced parallel arms, with an extension on each arm slidable on the arm. The pivots for the auxiliary roller are on the extensions. Hydraulic motor means are provided on the arms for moving the extensions so that the roller may apply substantial pressure either to the pressure cylinder or the plate cylinder, so as to maintain substantial tension on a plate or sheet mounted thereon and clamped at the leading edge only. Means are provided to limit the movement of the auxiliary roller toward the cylinders of the press when the carriage is in its retracted position.

The mechanism for clamping the trailing edge of the printing plate or rigging sheet includes a pair of jaws which may be fastened together to grip the edge of the plate or sheet between them. The radially innermost jaw is provided at each end with a channel extending along the periphery of the cylinder. Two rails are fixed on the periphery of the cylinder adjacent the ends of the channeled jaw. These rails have flanges which are received in the channels. Roller bearings are captured between the flanges and the bottoms of the channels. A row of spaced coil springs biases the lower jaw toward a position in which the plate is under tension. The lower jaw and the upper jaw assembled with it may be moved against the tension of the springs to a tension releasing position by means of a single cam journaled on a pin fixed to the middle of the cylinder and rotatable by means of an external tool. The follower for the cam comprises a roller bearing rotatable on an arbor fixed on the lower jaw. The cam is provided with a concave notch which engages the follower when the plate tension is relieved, so that the cam and follower remain securely in their tension relieving positions, until the cam is rotated by the external tool.

DRAWINGS

FIG. 1 is a fragmentary elevational view of an intaglio printing press embodying the invention, with certain parts broken away.

FIG. 2 is a fragmentary sectional view taken along the line 2--2 of FIGS. 1 and 3, on an enlarged scale.

FIG. 3 is a sectional view taken along the line 3--3 of FIG. 2, with certain parts omitted.

FIG. 4 is an enlarged fragmentary sectional view showing the mechanism for clamping the printing plates to the plate cylinder.

FIG. 5 is an exploded fragmentary view showing the mechanism for clamping the leading edge of the plate to the plate cylinder.

FIG. 6 is a sectional view taken along the line 6--6 of FIG. 4.

FIG. 7 is a sectional view taken along the line 7--7 of FIG. 6.

FIG. 8 is a sectional view taken along the line 8--8 of FIG. 6, showing the parts in positions in which the printing plate is under tension.

FIG. 9 is a view similar to FIG. 8, showing the parts in positions in which the plate tension is relieved.

FIG. 10 is a view taken along the line 10--10 of FIG. 4.

FIG. 11 is a sectional view on an enlarged scale, corresponding to a left to right reversed view of the lower portion of FIG. 4, with a cover for the clamping mechanisms added.

FIG. 12 is a sectional view taken along the line 12--12 of FIG. 11.

DETAILED DESCRIPTION

The press illustrated includes a front vertical frame member 1 and a rear vertical frame member 2 (FIG. 2). Between the frame members 1 and 2 are journaled a plate carrying cylinder 3 and an impression cylinder 4. Sheets of paper to be printed may be supplied by conventional sheet feeding mechanisms to a train of sheet feeding rolls 5, 6, 7, from which they are transferred to the impression cylinder 4, and pass through the nip between the impression cylinder and the plate carrying cylinder 3. The printed sheets are then removed by a conveyor 9, running over a sprocket 8.

The press illustrated is a multicolor press. The ink applying mechanism includes a carriage 10 (FIG. 1) on which are mounted three ink reservoirs 11, 12 and 13 connected by ink conveying roller trains 15, 16 and 17 to rollers 20, 21 and 22, which transfer the ink to the plate on the cylinder 3. The rollers 20, 21 and 22 are contoured, so that each contacts a portion only of the surface of the cylinder 3. Typically, only one color of ink will be applied to any given portion of the surface of the plate, although it may be arranged that colors overlap, if desired.

The plate carrying cylinder 3 turns clockwise, as viewed in FIG. 1. A wiping roll 25 is rotatably mounted so that it runs with its periphery in contact with the plate cylinder 3, and also becomes immersed in a suitable solvent in a tank 26. The wiping roll 25 removes the ink from the surface of the plate on the printing cylinder, between the lines on the plate, so that as the plate approaches the nip of the cylinders 3 and 4, the only ink remaining on the plate is in the recessed lines.

The plate cylinder 3 is driven by a motor 27 through a multiple V-belt drive 28 and a suitable gear train (not shown). Conveyor 9 is driven from the plate cylinder 5 through a bevel pass shown at 29 in FIG. 1. The wiping roll 25 is driven by a motor 30, which may be controlled as described in our copending application, Ser. No. 173,555, mentioned above.

The cylinder for applying and relieving printing pressure between the plate cyoinder 3 and the impression cylinder 4 is shown in detail in our copending application, Ser. No. 298,433, mentioned above.

AUXILIARY ROLLER -- FIGS. 2-3

An auxiliary roller 32 is rotatably supported on a pivotally mounted carriage 33. The carriage 33 comprises a pair of arms 34, 35, which are pivotally mounted on trunnions 36, 37, fixed on the inner sides of the front and rear frame members 1 and 2.

The left ends of the arms 34, 35 as they appear in the drawings, carry a T-shaped head, best seen at 35a in FIG. 3. The T-shaped head 35a has formed therein an arcuate slot 35b which receives the shank of a screw 40, which is threadedly received in the frame member 2. By tightening the screw 40, the arm 35 may be locked in any angular position.

In order to select the angular operating positions of the carriage 33 accurately, each of the arms 34, 35 is provided near its outer end with a housing 41, which encloses a locating pin 42. Each pin 42 has an enlarged head, tapered at its end, and is receivable in any one of three holes 43, formed in the frame members 1 and 2. A spring 44 is held in compression between a shoulder on the head 42 of the locating pin and the inner end of the housing 1, and biases the locating pin toward the position where its head is received in one of the holes 43. The outer end of the shank of pin 42 extends through the top of the casing 41 and is provided at its inner end with a handle 45 by means of which the head 42 may be withdrawn from one of the holds 43 for the purpose of shifting the operating position of the carriage 33.

The arms 34, 35 are provided with a pair of extensions 46, slidable in suitable channels provided in the arms 34, 35. The extensions 46 are operated by means of hydraulic motors 47, which are pivotally fixed at their left-hand ends to posts 48 fastened to the arms 34, 35. The hydraulic motors 47 operate piston rods 50, which are pivotally fixed to the extensions 46.

A pair of stops 51 are fixed on the frame members 1 and 2 in alignment with the ends of the extensions 46, when the carriage 33 is in its retracted position, as shown in full lines in FIG. 3. Each stop 51 is provided with an adjustable screw 52, by means of which the stop positions of the extensions 46 may be varied as required.

In the normal running condition of the press, the carriage 33 is in its retracted position, shown in full lines in FIG. 3, so that the extensions 46 engage their stop screws 52, and the surface of the roller 32 does not engage the surface of either the plate cylinder 5 or the pressure cylinder 4.

When a plate is being installed on the plate cylinder 5, the leading edge of the plate is first fastened to the plate cylinder 5 by means of a clamp generally indicated at 60 in FIG. 3. The carriage 33 is then released from its position illustrated in full lines and is turned clockwise from that position about the trunnions 36 to a position in which the pins 42 engage the uppermost holes 43 and the roller 32 engages the printing plate 61 adjacent the leading edge of the saddle 5a on which the plate is to be mounted. The plate cylinder 5 is then rotated counterclockwise, with the roller 32 holding the plate 61 smoothly and firmly against the saddle 5a. When the trailing edge of the plate moves near the roller 32, then that trailing edge may be clamped in a clamping mechanism 62, shown in detail in FIGS. 4 and 6-12.

A similar procedure is used in applying a flexible rigging sheet to the pressure cylinder 4. The clamps 63 and 64 used respectively at the leading and trailing edges of the rigging sheet on the pressure cylinder 4 need not be exactly like the clamps 60 and 62 of the plate cylinder, since the location of the rigging sheet on the pressure cylinder 4 does not involve the degree of precision required for the location of the plate 61 on the plate cylinder 5.

LEADING EDGE CLAMP -- FIGS. 4-5

The clamping mechanism 60 for the leading edge of the printing plate 61 is best seen in these two figures. This clamping mechanism 60 includes an inner jaw 65 recessed in and fastened to the plate cylinder 5 by screws 69 (FIG. 10), and an outer jaw 66, which may be fastened to the inner jaw 65 by means of a series of spaced machine screws 67. Outer jaw 66 is provided on its inner face, at its margin remote from the plate 61, with a projecting flat surface 68, whose thickness is less than the thickness of the plate 61, so that the jaws 65 and 66 will tend to contact on the inner teeth of the jaws when in their clamped positions. The face of the jaw 66 which engages the plate 61 is provided with a plurality of rows of sharp pointed teeth 66a near the edge of the plate 61, and with a plurality of rows of teeth 66b having flattened or truncated points, engaging the plate 61 farther from the edge than the sharp points 66a. This construction insures that the marginal edge of plate 61 will be held tightly by the sharp points 66a, and allows the plate 61 to shift laterally where it is located under the flat points 66b.

The outer jaw 66 is also provided with a plurality of spaced openings 66c (FIGS. 4, 8 and 9), which loosely receive the heads of locating pins 70, which are firmly fixed in the lower jaws 65, and which are received in openings in the plate 61 to fix its location precisely and accurately with respect to the cylinder 5.

TRAILING EDGE CLAMPING MECHANISM -- FIGS. 4 and 6-10

The trailing edge clamping mechanism 62 includes an inner jaw 71 and an outer jaw 72. The jaws 71 and 72 are located in a recess 73 formed in the outer surface of the cylinder between the plate supporting saddles. The inner jaw 71 does not touch the bottom of that recess, but is supported outwardly from it, as clearly appears in the drawings, especially FIGS. 4 and 7-9. The inner jaw 71 is provided at each end with a channel 71a (FIG. 7), extending parallel to the inner and outer surfaces of the jaw. A pair of rails 74 are fixed to the bottom of the recess 73 by means of bolts 75. The upper ends of the rails 74 have flanges projecting toward the inner jaw 71, and received in the channels 71a. Roller bearings 76, best seen in FIG. 7, are captured between the flanges of the rails 74 and the bottoms of the channels 71a. The flanges of the rails 74 are provided with recesses 74a (FIG. 6), to receive the bearings 76 and hold them in position. The vertical dimensions of the inner jaw 71 and its channel 71a, as compared to the vertical dimensions of the rails 74 and its flange, as viewed in FIG. 7, are such that the inner jaw 71 is supported solely by the rails 74, and its under surface is spaced above the bottom of the recess 73.

The inner jaw 71 is provided with a plurality of spaced apertures 71b (FIGS. 4 and 7), in which are received springs 77, which are held in compression between one wall of the recess 73 and a spring retainer 78 threadedly received in the aperture 71b, and adjustable in position by means of a hexagonal head 78a. This assembly is best seen at the top of FIG. 4.

The springs 77 bias the inner jaw 71 and the entire clamping mechanism 62 in a direction to maintain the flexible printing plate 61 under tension.

The inner jaw 71 is provided with a second row of spaced apertures 71c, in which are threadedly received a plurality of screws 80 having hexagonal heads 80a at their outer ends. The inner ends of the screws 80 abut against a surface at the side of the recess 73.

When the printing plate 61 is first installed on the press, the screws 80 are backed off so that their ends are spaced from the side of the recess 73. The only force then tending to hold the printing plate 61 under tension is the force due to the springs 77. After the plate has been installed on the press, the screws 80 may be tightened, thereby placing the plate 61 under additional tension. Note that there is no structure limiting the movement of the lower jaw 71 in a downward direction as viewed in FIG. 6. In other words, the forces due to the spring 77 and the compression in the screws 80 are opposed only by the tension in the plate 61, so that the plate 61 is held firmly and smoothly in place on the press.

In order to relieve the tension in the plate 61, the screws 80 must first be backed off so that their inner ends are not engaging the sides of the recess 73. A cam 82 is provided for moving the lower jaw 71 against the compression of the springs 77. The cam 82 is mounted on a pivot pin 83, and is rotatable on that pin by means of an externally applied key or other tool, as shown at 84 in FIGS. 8 and 9. In the plate tensioning position shown in FIG. 6, the cam 82 is spaced from a recess 71d formed in the lower jaw 71. A cam follower is located in the recess 71d, and comprises a roller bearing 85 rotatable on a stud 86. When the cam 82 is rotated through 90.degree. from the position shown in FIG. 6, the surface of the cam engages the roller bearing follower 85, and forces the lower jaw 71 upwardly, as viewed in FIG. 6 and also in FIG. 9. This compresses the springs 77, and relieves the tension in the printing plate 61, as is shown in FIG. 9.

The outer jaw 72 is similar in structure and function to the outer jaw 66 of the clamp 60, described above. The outer jaw 72 is held in place in clamping position on the lower jaw 71 by means of a plurality of screws 87, best seen in FIGS. 6-7.

The outer jaw 72 is longer than the inner jaw 71, so that its ends overhang that inner jaw and the rails 74, as seen in FIG. 7. A pair of springs 88 are held in compression between the ends of the upper jaw 72 and the rails 74. When the screws 87 are loosened to remove a plate from the clamp, the springs 88 are effective to separate the jaw 72 from the jaw 71, thereby readily releasing the plate 61 from the grip of the clamp.

When the cam 82 is rotated 90.degree. from the position shown in FIG. 6, a concave recess 82a becomes alined with the roller bearing 85 and holds the cam 82 and follower 85 securely in position, so that the tension in the printing plate 61 continues to be relieved.

COVER PLATE -- FIGS. 11-12

These figures illustrate a cover plate 91, which is placed over the clamp assemblies 60 and 62, to close the space between those clamp assemblies and thereby to prevent the accumulation of dirt or foreign material in the recess 73. As seen in FIG. 11, the plate 91 has a pair of wings 91a and 91b, each having a gasket 92, 93 of compressible material bonded to its extremity. The gasket 92 is adapted to engage the leading edge of the printing plate 61, the gasket 93 is adapted to engage the outer surface of the outer jaw 71 of the clamp mechanism 72.

The cover plate 91 has integrally formed therewith two upstanding lugs 91c, in which are received a pair of locking rods 92. Each rod 92 has a tapered tip 92a adapted to engage a corresponding recess in an end plate 93 of the cylinder 5. A spring 94 encircles each rod 92 between one of the lugs 91a and a shoulder 92b formed on the rod 92. The spring 94 biases the locking rod 92 toward the locking position shown in FIG. 12, in which the tip 92a engages the recess in end plate 93. The inner ends of the locking rods 92 are encircled by a common sleeve 95. Each rod 92 has pinned to its inner end a sleeve 96 to which is welded a handle 97 having a projecting end 97a accessible through an opening in the plate 91. By moving the handles 97a to the dotted line positions shown in FIG. 12, the locking pins 92 are withdrawn from the recesses in the end plates 93, so that the cover assembly 91 may be removed.

Claims

We claim:

1. A printing press, comprising:

a. a plate cylinder;

b. an impression cylinder rotatable about an axis parallel to the axis of the plate cylinder;

c. means including a frame supporting said cylinders for rotation about said parallel axes and for movement of one of said cylinders in a direction perpendicular to its axis to shift said one cylinder between a printing position in which the cylinders are in rolling contact and a non-printing position in which the cylinders are separated;

d. means on each cylinder for clamping the leading edge of a sheet;

e. means on each cylinder for clamping the trailing edge of a sheet;

f. a roller for applying pressure to such a sheet and its associated cylinder during installation of the sheet on the cylinder; and

g. means including a carriage supporting the roller for movement between a retracted position spaced from both the cylinders and either of two active positions in which it engages one cylinder or the other.

2. A printing press as in claim 1, including means for pivotally supporting the carriage for movement between three angular positions corresponding to the retracted position and the two active positions of the roller.

3. A printing press as in claim 1, including means for locking the carriage in any of said three angular positions.

4. A printing press as in claim 1, in which said carriage includes:

a. two parallel spaced arms pivotally mounted for rotation about a common axis;

b. an extension on each arm, slidable on its associated arm;

c. pivots for the roller on said extensions.

5. A printing press as in claim 4, including motor means for driving the extensions along the arms.

6. A printing press as in claim 5, including stop means mounted on the frame of the press for limiting movement of the roller toward the cylinders when the carriage is in its position corresponding to the retracted position of the roller.

7. A printing press as in claim 1, in which:

a. said plate cylinder has a saddle for receiving a printing plate and a recess at the trailing end of the saddle for receiving a clamp;

b. said trailing edge clamping means includes a pair of jaws extending substantially the full axial length of the plate and engageable with the trailing edge of the plate, at least one of said jaws having channels at its ends extending parallel to the plate;

c. a pair of rails attached to the cylinder and having flanges received in said channels, said flanges and channels cooperating to support the slidable clamp;

d. spring means biasing the slidable clamp in a direction to stress the plate in tension over the saddle; and

e. cam means operable to stress the spring means in a sense to relieve the tension in the plate.