US1724741A

US1724741A - Method of and means for finishing printing plates

Info

Publication number: US1724741A
Application number: US150858A
Authority: US
Inventors: Harold E Woodward
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-11-26
Filing date: 1926-11-26
Publication date: 1929-08-13
Anticipated expiration: 1946-08-13

Description

Aug. 13, 1929. H. E. WOODWARD METHOD OF AND MEANS FOR FINISHING PRINTING PLATES Filed Nov. 26, 1926 4 Sheets-Sheet A g- 1929- H. E. WOODWARD 1,724,741

METHOD OF AND MEANS FOR FINISHING PRINTING PLATES Filed Nov. 26, 1926 4 Sheets-Sheet 2 Q Q F-M T IT k N W e/7760 a 5. Wad/494a QQ mm Aug. 13, 1929.

H. E. WOODWARD 1,724,741 METHOD OF AND MEANS FOR FINISHING PRINTING PLATES Filed Nov. 26, 1926 4 Sheets-Sheet 3 Patented Aug. 13, 1929.

UNITED STATES HAROLD E. WOODWARD, OF UNIVERSITY CITY, MISSOURI.

METHOD OF AND MEANS FOR Application filed November The invention relates to methods of and means for finishing printing plates, one of the objects being to very accurately finish the back and face of a printing plate, so as to provide the desired surfaces on each side of the plate, at the same time removing the excess material from the back of the plate to reduce the plate to a predetermined thickness.

A further object is to obtain a very high degree of accuracy in these finishing operat-ions in an extremely simple manner, requiring very little time, and without the ex ercise of any special skill or labor on the part of the operator.

Prior to this invention, printing plates and especially electrotypes have been formed with more or less irregular printing faces, andit has been customary to employ a skilled operator for the purpose of locating all of the printing faces in the same plane, or in predetermined planes desired for the printing operation. In following the old practice, the operator first ascertains the locations of undesirable depressions, or low spots in the printing .face, and he then subjects the back of the plate to numerous hammering operations at the predetermined areas for the purpose of flattening the print- 0 ing face. These operations require a great deal of time on the part of a skilled operator, and after the face has been thus finished to the satisfaction of the operator, the back of the plate is quite irregular as a result of the hammering. Therefore, the next operation in the old p "actice consists in finishing the back of the plate, and the workman endeavors to perform this operation without changing the condition of the face of the plate.

The highest accuracy cannot be obtained in this old practice, for the elimination of irregularities in the printing face depends mainly upon the judgement of a workman using rather uncertain means to locate the inaccuracies and a hammering device to remove them.

Some printing plates have areas requiring a large amount of ink and other areas requiring only a relatively small quantity. For example, a large background to be printed in a solid color is often associated with small letters, or with a half-tone consisting of numerous minute dots, all in the same plate, and in such cases care must be FINISHING PRINTING PLATES.

26, P326. Serial No. 150,858.

exercised to avoid the delivery of too much ink to the small projections on the printing plate. supplied with enough ink to properly print the large background, but the pressure of the roll on the small projections should be relatively slight, so as to avoid blurring vhic-h occurs when too much ink is applied to such projections.

Therefore, a further object is to form depressions in the areas of half-tones or other small projections on the printing plates, and to vary the depth of the depressions in accordance with conditions found in the plate. For example, a half-tone comprising numerous minute projections may be depressed about ten one-thousandths ,of an inch, while letters large enough to be easily read, may be depressed about five one-thousandths when surrounded by a background printed in a solid color. I' will hereafter describe a method in which the desired depressions can be formed during the operation of finishing the back and face of a printing )late.

\Vith the foregoing and other objects in view, the invention comprises the novel method, construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention comprehends changes, variations and modifications which come within the scope of the claims hereunto appended.

Briefly stated, the method herein described comprises the operation of simultaneously finishing the back and face of a printing plate, and if desired this single operation may include the step of depressing an area of the face of the plate. In the preferred form of the invention, the plate is pressed between a. finishing member contacting with the .face of the plate and another finishing member cont-acting with the back. One of these finishing members may be a rotating cutting member contacting with the back .of the plate to remove excess material and to provide the desired flat back surface. The other finishing member has asurface corresponding to the desired printing face, and during the cutting operation the plate is subjected to a pressure great enough to cause its face to conform to this surface. The plate is of. course flexible enough to The yieldable inking roll should be yield in response to the high pressure, so that the printing face will accurately conform to the surface of the finishing member contacting therewith. 1 ill hereafter show how an under-lay can be used as a deforming member to produce depressions in the face of the plate.

Fig. 1 is a top view of a machine embodying. the features of this invention, a portion of the bed being broken away.

Fig. 2 is a longitudinal section taken approximately on the line 2-2 in Fig. 3.

Fig. 3 is an end view of the machine, with some of the parts shown in section.

F at is an exaggerated diagram showing a portion of a cutting roll contacting with the back of a plate, and an under lay between a bed and the face of the plate.

Fig. 5 is an enlarged fragmentary detail view showing printing elements on the face of a plate as they appear before the finishing operation.

Fig. 6 shows the same elements they appear after the finishing operation.

To illustrate one form of the invention, 1. have shown a printing plate A adapted to be finished while confined under pressure between a rotary cutting-roll 1 and a bed 2, the latter having a fiat top surface to receive either the printing face of the plate, or an under-lay B which will be hereafter dcscribed.

The rotary cutting roll 1 is mounted in bearings 3 and provided with driving gears 4; which may be driven by any suitable power. The bearings 23 are adjustable vertically to move the cutting roll toward and away from the bed 2. Any suitable means may be eniploycd to adjust these bearings and to simplify the illustration I have shown plain screws 5 above and below said bearings. The

roll 1 is formed with spiral cutting ribs 3' on its periphery.

Straight ribs, or bars, 7 are located at a angle to each other on the bed 2, and the plate to be'finished is arranged in the corner former at the junction of these ribs, as shown in Fig. 1. The bed 2 is slidably mounted on horizontal faces 8 at the sides of a base 9, and this slidable bed has a pair of large ribs 10 at the bottom.

A feed screw 11, arranged longitudinally of the bed, lies between theribs 10 and passes through a traveling nut member 12, the latter having wings 13 extending into recesses 14- formed in said ribs 10. The nut 12 travels in response to rotary movements of the screw 11, thereby imparting longitudinal movement to the bed 2. The screw can be rotated in opposite direct-ions'to reciprocate the bed. A worm. gear 15 on one end of the screw is driven. by a worm 16 on a shaft 17. The screw 11 is supported in bearings 18.

The nut 12 is closely fitted to the walls of the recesses in the ribs 10, so as to transmit longitudinal. movement to the bed 2, but this interlocking connection does not revent transverse movements of the bed, and while this bed is moving longitudinally it is preferably reciprocated transversely, thereby impa'rting a wabbling motion to the printing plate as it travels under the cutting roll 1.

To illustrate this feature]: have shown elongated gear teeth 19 at the bottom of one of the ribs 10, and segmental gears 20 and 21 adapted to mesh with said teeth. The segmental gears are fixed to a shaft 22 mounted in bearings 23, and one of said gears is provided with an operating arm 24 to which an operating rod 2 1' is connected for the purpose of oscillating the segmental When the machine is in service, the bed 2 slides on the horizontal faces 8. Itis moved longitudinally by means of the screw 11 and nut 12, and at the same time oscillated t ansversely by the action of the segmental gears 20 and 21 meshing with the teeth 19. T iis wabbling motion does not vary the distance between the horizontal top face of the bed and the horizontal cutting roll 1, but it aids in the operation of shaving the back of the plate and enables this operation to be carried out while the bed is moving longitudi nally in either direction.

The under-lay B, shown in Fig. l, comprises a sheet of metal 25 contacting with the horizontal top face of the bed 2, fillers 26 on the top of said metal sheet, and thin sheet material 27 extending over the fillers and having their margins cemented or otherwise secured to the metal sheet 25. The fillers 26 will vary in thickness in accordance with the depths of the depressions to be formed in the face of the printing plate, and it is to be understood that this f'e ture has been exaggerated for the purpose of illustration in Fig. 4. The actual depth of a depression is only a few thousandths of an inch. 7 a

Fig. 5 is an exaggerated view suggesting the condition of the printing face before the'finishing operation. The elements 28 may be regarded as the tiny members forming the printing face of a half-tone, or as the members for printing small letters. In either case, if they are formed on a plate which is prepared to also print a large surface in a solid color, the small inembers should be depressed so they will not receive an excess of ink from the inking roll. The under-lay B is therefore prepared with fillers 26 of the desired thickness in the areas to be depressed.

Fig. 6 suggests the condition of the face of the plate after it has been pressed onto the top of the under-lay. The printing faces Ill) of the depressed elements 28 lie in the same plane, and the entire face of the plate ac curately conforms to the surface of the under-lay. Or, if the under-lay is not used, the face of the plate will conform to the fiat surface of the bed 2.

The pressure for this finishing operation is obtained by forcing the rough printing plate under the cutter 1 which shaves the back of the plate while forcibly pressing its face onto the bed 2, or onto the under-lay. The cutting ribs 6 are adapted to make alined discontinuous contacts with the back of the plate, and as the cutter l is rotated, the contact points progress in the direction of their alinement. In other words the pressure at the cutter is exerted in a progressive manner as the shaving proceeds from one edge of the plate to the opposite edge, and the bed is preferably wabbled to more effectively distribute the pressure throughout the plate.

In actual practice, I have found that this method very effectively eliminates irregularities that have heretofore been removed by hand, and that it produces a highly accurate printing surface free from numerous defects that in practice are not removed by the hand operations. The progressive pressing operation is similar to the operation of pressing clothing, and the like, by moving a hot iron in various directions over the article, to obtain results that cannot be accomplished by pressure alone. However, in the present method the pressure is greater and it is preferably distributed by using spiral cut ting ribs on the roll, as well as by the motion of the bed which carries the plate.

Instead of mutilating the back of the plate by hand operations intended to remove defects from the face, the present invention simultaneously finishes the back and face, thereby producing a plate of the thickness desired for printing. An extremely high degree of accuracy in all of these operations can be easily and quickly obtained by an operator having no special skill in this art.

I claim:

1. The method which comprises simultaneously finishing the back and face of a printing plate by shaving the back of the plate and at the same time forcibly shifting improperly located printing elements to the desired printing positions by pressing the face of the plate onto a finishing member and moving said finishing member to distribute the pressure throughout the plate.

2. The method which comprises simultaneously finishing the back and face of a printing plate by compressing the plate between a finishing member contacting with the face of the plate and a rotating cutter having spiral cutting ribs contacting with the back of said plate.

3. The method which comprises finishing the back of a printing plate and at the same time deforming the plate to provide a depression in the printing face of said plate.

4. The method which comprises simultaneously finishing the back and face of a printing plate by shaving the back of the plate and at the same time forming a depression in the printing face by forcibly pressing the face of the plate onto an under-lay.

5. The method of finishing printing plates which comprises arranging an under-lay between a flat surface and the face of a printing plate, forcing the face of the plate onto the under-lay to form a depression in said face, and at the same time shaving the back of said plate.

6. The method of simultaneously finishing the back and face of a printing plate which comprises deforming the plate between a rotating cutting roll contacting with the back of the plate and an under-lay contacting with the face of said plate, so as to depress the printing elements at the under-lay.

'7. The method which comprises simul taneously finishing the back and face of a printing plate by pressing the plate between a cutting member contacting with the back and a finishing member contacting with the face, and at the same time imparting a wabbling motion to one of said members without varying the distance between said members.

8. The method of simultaneously finishing the back and face of a printing plate which comprises arranging an under-lay on a flat bed, shaving the back of the plate, pressing its face onto the underlay to form a depression in said face and at the same time wabbling said bed.

9. In a means for simultaneously deforming and finishing the back and face of a printing plate, a cutting member adapted to contact with the back of the plate, a finishing member having a surface corresponding to the desired printing face, and means whereby the printing plate is pressed between said members to deform its face to the contour of the finishing member, so as to shave the back of the plate and at the same time finish the face.

10. In a means for simultaneously finishing the back and face of a printing plate, a rotary cutter adapted to contact with the back of the plate, a. bed having a finishing member provided with a surface corresponding to the desired printing face, and operating means whereby the bed is moved to forcibly push the printing plate between the rotary cutter and said surface.

11. In a means for simultaneously finishing the back and face of a printing plate, a cutting member adapted to contact with the back of the plate, a finishing member having a surface corresponding to the desired printing face, and means whereby the printing plate is pressed between said members,

so as to shave the back of the plate and at the same time finish the face, said means including a device whereby a wabbling motion is imparted to one of said members.

12. In a means for simultaneously deforming and finishing the back and face of a printing plate, a rotary cutter having spiral cutting ribs adapted to contact with the back of the plate, a bed having a deforming member provided with a surface corresponding to the desired printing face, and operating means whereby said bed is moved to press the printing plate between said rotary cutter and said surface, said operating means including a device whereby a wabbling motion is imparted to said bed.

13. In a means for simultaneously finishing the back and face of a printing plate, a cutting member adapted to make alined discontinuous cutting contacts with the back of the plate, said contacts moving in the di rection of their alinement, a finishing memher having a surface corresponding to the desired printing face, and means cooperating with said members to deform and finish both sides of the printing plate.

142. The method which comprises simultaneously finishing the back and face of a printing plate by shaving the back of the plate while subjecting the plate to pressure at the shaving element and thereby forcibly pushing the improperly located printing elements to the desired printing positions.

15. The method of simultaneously finishing the back and face of a substantially flat printing plate which comprises confining the plate between a shaving member contacting with the back of the plate and a finishing member having a flat face contacting with the face of the plate, while pressing the portions of the plate between said shaving member and the fiat face and thereby forcibly shifting improperly located printing elements relative to the other printing elements so as to push said improperly located printing elements onto said fiat face. V

16. The method of simultaneously finishing the back and face of a printing plate which comprises arranging the plate between a finishing member contacting with the faceof the plate and a shaving member contacting with the back of the plate, and compressing the material between said shaving member and finishing member and thereby forcibly shifting the improperly located printing elements relative to the other printing elements, so as to forcibly push said improperly located printing elements to the positions desired for printing.

17. The method of simultaneously finishing the back and face of a printing plate which comprises arranging the printing plate between a finishing member contacting with the face of the plate and a cutter contacting with the back of the plate, at the same time compressing the material between said cutter and finishing member and thereby forcibly shifting improperly located printing elements relative to the'prop erly located printing elements, so as to locate each of said printing elements in the desired printing position, and moving both the cutter and the finishing member to perform said forcible shifting operations at all of the improperly located printing elements.

18. The method of simultaneously finishing the back and face of a printing plate which comprises arranging the printing plate between a cutter which shaves the back of the plate and a finishing member having a fiat face contacting with the face of the plate, at the same time compressing the material directly between said cutter and the flat face and thereby forcibly shifting the printing elements which do not initially contact with said flat face so as to forcibly push the improperly located printing elements relative to the properly located printingelements, the degree of compression at the cutter being great enough to force said improperly located printing elements onto said flat face.

In testimony that I claim the foregoing I iereunto affix my signature.

HAROLD E. -W0 ODVVARD.