US1269687A - Gripper attachment for printing-presses. - Google Patents

Description

S. E. DITTMAN. I GR|PPER ATTACHMENT FOR PRINTING PRESSES.

APPLICATION .FILED AUG..27. 1915.

1,269,687. I Patented June 18, 1918.

ED STATES: PATENT orrroin.

SAMUEL E. DITTMAN, OF NEW YORK, N. Y., ASSIGNORTO MIEI-ILE PRINTING PRESS &

MANUFACTURING- COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

GRIPPER ATTACHMENT FOR PRINTING-PRESSES.

Specification of Letters Patent. Patented June 18, 1918.

Application filedAugu'st 27, 1915'. Serial no.f47,575.

To all whom it may concem:

Be it known that I, SAMUEL E. DITTMAN, a citizen of the United States, and a resident of New York, in the county of New'York and State of New York, have invented certain new and useful Improvements in Gripper Attachments for Printing-Presses; and

v I do hereby declare that the'following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference gripper fingers, which form a part of the paper or sheet retaining mechanism of a printing press. p

v To those skilled in the art of printing and familiar with the construction of printing 1 presses and particularly that type known as the cylinder press, a common construction for such presses embraces, in general, a revolving cylinder provided with gripper fingers, acting to engage and hold the sheet to be printed during the printing operation,

said: cylinder being mounted in horizontal positionupon the bed or frame of the press. The sheet of paper or material to be printed or receive the impression isapplied to the revolving. cylinder, which carries the paper,

with a rotary motion, in contact withrthe type or printing form, the same belng mounted upon the bed of the press, which travels forwardly and rearwardly beneath v thecylinder with a reciprocating movement.

To the surface of the cylinder or tympanis applied the blank sheet of paper, and upon receiving an impression, by its contact with the moving type forms, it is delivered or re leased from the cylinder and a blank sheet immediately applied and the printing opera tion again repeated. 7

Printing presses of this type are ordinarily provided with gripper fingers mounted upon or set in the cylinder and adapted to grip the front transverse margin ofthe sheets as the same are applied to the cylinder or, as commonly stated, fed to the press.

A familiar construction for a gripper mechanism consists of a shaft set in the cylinder-[adj acent to one margin of the tympanand extending transversely thereof, said shaft being provided at intervals throu hout its length with a series of gripper 11- gers, which project at right angles to the shaft and are adapted to be moved into'and out of contact with thesurface of the cylinder by a rocking movement imparted to the shaft.

fingers are ordinarily made of metal and act to securely grip the sheet by pressure applied thereto through the mediuln of suitable tension means acting on the shaft.

Although it is the purpose, in the construction of thefgripping mechanism, that all of the fingers shall exert an equal pressure upon the sheet whereby, a uniform gripping action is present throughout the margin of the sheet, it has been found in practice that slight variations occur in the pressure exerted by the gripper fingers, due to various causes that will be hereinafter pointed out, and as aresult the gripper fingers do not exert a uniform pressure throughout the margin of the sheet,'and as a further result the sheets are not held firmly during the printing operation, thereby causing difficulty in obtaining proper registering of the sheet and type form and the main taming of the proper margins on the sheets.

The purpose of my invention is to provide an attachment which may be easily applied to the ends of the gripper fingers, its purpose being toincrease the tion of the fingers and to equalize the pres sure thereof and thereby secure a uniform gripping of the sheet along its margin and eliminate the difficulties ordinarily encountered and as hereinafter more fully Figure 1 is a perspective view of acylinder of a printing press, showing the arrangement of the gripper fingers;

Fig. 2 is a perspective viewrof V one form of the gripper attachment; 3

Fig; 3 is a perspective'view showingthe contact surface of'the gripper attachmentprovided withrthe before mentioned shaft 11 mounted upon the cylinder in a suitable manner and adapted to operate as before set forth- Mounted upon the shaftis a serles of gripper fingers 12 extending transversely from said shaft in a downwardly dlrection and engaginga .margin .of a sheet of paperv 13, which is held in printing position against the surface or tympan of the cylinder.

As already suggested, the gripper attachments are adapted to be applied to the ends of the gripper fingers, and, althoughthe same maypartake of several forms, depend ing on the. means employed 111 attachmg them to the. gripper fingers, all of the forms embrace a common member, namely, a pad or block of material secured at the under side and at the ends of the gripper fingers and interposed between the ends of said fingers and the sheet of paperto be held. The pad or block is preferablycomposed of rubber or other material of a soft, pliable nature and preferably having natural adhesive or gripping qualities.

Referring to one of the forms (Flg. 2), the same comprises a rectangular block or pad 14 of rubber of a length preferably equal to the width of the gripper finger and a width suflicient to provide an ample gripping or contact surface. Theblock or pad is of-sufiicient thickness to space the-fingers from the sheetto be held thereby and to afford asuitable degree of resiliency. As shown, the thickness of the pad is slightly greater at the margin adjacent to the end of the finger than at its rear margin, thereby affording the under or contact surface of the pad a slight taper from front to rear thereof "with respect to the under surface of the finger. In this manner the contact surface ofthe pad assumes a.more,nearly tangential'positionwith respect to the surface of the cylinder, and as a result a better gripping, contact is effected. The under or contact surface is, furthermore, serrated or roughened in any suitable manner, as shown in Fig. 3, the obvious purpose of so doing, being to increase the gripping tendency of the pad. In this. form-oftlre attachment the following means-is 'employedrto secure the same to the gripper fingers. Projecting upwardly from the upper-surface ofthe block Mare provided two cylindric nubs or dowels 15 arrangedsymmetrically with respect to the longitudinal and transverse center lines of the pad and spaced apart from each other. These dowels are preferably of rubber and molded integral with theblock, the height of the same being slightly greater than the thickness of the metalfiugers. These dowels are adapted to register with and to engage two apertures similarly arranged at the end of each gripper finger. Thus, when the dowels are in.- sertedv in, said apertures, the.- margins of the block. and end portion of the gripper finger are substantially flush, said dowels projecting a short distance through the apertures,

the diameters of the latter being substanthereby affording a more permanent attachment.

In Figs. 4' and 5 is illustrated'another form of the device, comprising a body member16 preferably formed of rubber or like material molded into the desired form and openat one side and forming a pocket'or space 17 therein, the dimensions of said pocket being substantially equal to the width and thickness of the end portions of the gripper fingers. Extending from the. opposite longitudinal edges of the pocket are two flaps 19, 19 of rubber. These flaps act as means for securing the attachment to the gripper fingers, as will-hereinafter appear. Upon one side of the body member and ad-' jacent the pocket-forming portion thereof is the block or pad 20, of'rubb'er or like material, rectangular in shape and integral with the body member, the same being formed, in effect, by materially increasing the thickness of one wall of the body member throughout one wall or side of the pocket. The surface of the pad 20 is roughened or serrated as 1n the form of the attachment previously described. This form of gripper attach ment is applied'to the ends of the'gripper fingers by inserting said ends thereof into the pocket formed by the body member, with the pad'QO facing downward. Asa

means for securely holding the attachment per fingers. This may be the result of one of several causes, such as a varying tension in the gripper fingers, a varying in the thickness of the paper stock used or in the thickness throughout all portions of a single sheet of paper, or a variation in the character of the surface of the paper stock being printed. The absence of a uniform gripping action during the printing operation often results in the sheet being shifted from its proper registering relation with the type form, and the consequent efiecting of the improper location of the impression upon the sheet. Loss of time, labor, and material are manifestly the consequences. Furthermore, in case one or more of the gripper fingers exert an excessive ressure, it gives rise to a tendency by these 'ngers to dig, to an excessive degree, into the sheet and surface of the tympan with the attendant mutilation of the same. The presence of an elastic pad between the gripper finger and the sheets to be printed, however, tends to equalize the pressure exerted by the gripper fingers and to compensate for any excess pressure in one or more of the gripper fingers, by reason of the compressive and elastic features of the rubber pad or block, and to thereby eliminate the undesirable features of operation men tioned.

The equalizing and compensating effect of the gripper attachments together with length of time necessary to complete it,

and to automatically correct any of the faults hereinbefore suggested that might arise during thev operation of the press.

It is apparent from the foregoing description of the invention that. such devices may be constructed in any one of several ways, and for that reason I .do not wish to be limited to the particular construction herein shown and described, except in so far as specifically pointed out in the appended claims.

I claim as my invention:

1. The combination with a gripper finger of a printing press, of a pad member made of resilient material, and said pad member and said finger being provided with interengaging means adapted to removably connect said pad member with said finger and to hold said pad member from rotation with respect to said finger.

2. The combination with a gripper finger of a printing press, of a relatively flat pad member made of resilient material, and means for removably attaching said pad member to said finger, comprising a plurality of dowels integral with said pad member and extending into apertures in said finger. p

In testimony that I claim the foregoing as my invention I aflix my signature in the presence of two witnesses, this 23rd day of August, A. D. 1915.

SAMUEL E. DITTMAN.

Witnesses:

E. W. BAKER, N. H. Ernos.

Copies of this patent may be obtained for five cents each, by addressing the Gonimissioner of Patents, Washington, D. 0.

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