US1405949A - Gripper for printing presses - Google Patents

Description

R.- T. SNELL.

GRIPPER FOR PRINTING PRESSES.

APPLICATION FILED DEC. I0, I920- 1,405,949, Patented Feb. 7, 1922.

7 2 SHEETSSHEET I- Zv/E/v 727/? R. T. SNELL.

GRIPPER FOR PRINTING PRESSES.

APPLICATION FILED DEC.10, 1920.

1,405,949; Patented Feb. 7, 1922;

2 SHEETS-SHEET 2.

UNITED STATES ROBERT T. SNELL, OF CLEVELAND, OHIO.

GRITPER FOR PRINTING PRESSES.

Specification of Letters Patent.

Patented Feb. '7, 1922.

I Application filed December 10, 1920. Serial No. 429,675.

Z '0 all whom it may concern:

Be it known that I, Bonner T. SNELL, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Grippers for Printing Presses, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to printing grippers adapted for holding a sheet of paper in position during the printing operation, and is primarily concerned with improvements in the means for retaining a sheet adjacent the platen of a printing press.

Some of the means now employed for retaining a sheet of paper in position, embody adjustable rigid grippers having one or more fingers extending inwardly therefrom.

With the old form of grippers embodying fingers slidably mounted on rigid bars, I have found that it is diflicult to obtain accurate and minute adjustment of the fingers. Furthermore, the construction of the fingers has been more or less complicated and has required several pieces to complete the entire device.

In a number 'of instances I have found that the fingers were unable to securely grip the sheet against the platen, and consequently air pockets have been formed beneath the sheet during the printing operation; and as a result of such pockets the printing has' often been blurred.

An object of this invention is the provision of a finger particularly adapted for effectively holding a sheet against the platen during the printing operation and for'preventing the formation of air pockets beneath the sheet. I

Another object is the provision of a printing gripper having means thereon for readily adjusting the gripping mechanism and for enabling an operator to render accurate and minute adjustments in a minimum of time.

Still another object is the provision of a gripper finger that is light, yet strong in construction, and which is free from sharp projections on that portion thereof which may be engaged by the hands or clothes of an operator.

In accomplishing the above objects I prefer to employ a gripper bar having sawteet-h serrations, and adapted to support fingers which are slidably mounted thereon.

The particular method of constructing the shdable fingers together with the method of supporting them on the bar constitute the novel features of my invention. These features will be more fully described in detail,

in connection with the accompanying drawings, and the essential characteristics thereof will be set forth in the claims.

In the drawings Fig. 1 is a side elevation of a ob printing press, having my invention applled thereto; Fig. 2 is a plan of a platen with the-grippers in position above a sheet prior to the printing operation; Fig. 3 is an enlarged plan of a gripper bar'having adustable fingers mounted thereon; Figs. 4:, 5 and 6 are details showing the manner of construction of the gripper finger. In F 1g. 1 is shown ajob press, which is illustrative of any form'of printing press with which my invention may be employed. In this view, A indicates a side frame'member carrying the usual platen B, and equipped with any suitable mechanism not shown, for presenting theplaten to the type D. The usual rotary inking plate is illustrated at F, which in addition to the type and associated mechanism is carried on a pivoted frame G. This frame is operated by the ordinary connecting link K between the frame and the crank pin on the gear L. The

gripper is represented generally at M, and is provided with means, not shown, for bringing it into contact with the paper as the platen is lowered, and brought into contact with the type D.

Designating the parts shown in the draw- 1ngs by the use of reference numerals, in Fig. 3, 10 designates a form of gripper bar, adapted for use with my invention. This bar comprises a narrow strip of material provided with an aperture at 11 for securing the inner end thereof to a platen, and provided with an arm extending upwardly therefrom, an amount sufficient to gri the longest sheet of which the press unc er consideration is capable of handling. One side 12 of the bar is smooth, while the other side thereof is provided with saw-teeth serrations 13 extending nearly the entire length of the bar. .The extreme end of the bar is rounded, as at 14, to present a comparatively smooth surface to that portion which is adjacent the operator of the printing press. These serrations may have a pitch, which can be varied in accordance with the degree of accuracy in adjustment required, and the points of the teeth may be hardened to provide a durable wearing surface.

When the bars are mounted on the platen they are positioned as shown in Fig. 2, where the smooth sides 12 face inwardly and are.

7 one end 16 of the platen B and feeds the sheets, one at a time, against the stops 17 at the other end thereof.

To retain the sheet securely against the platen, I provide one or more fingers, which are slidably mounted on the gripper bar, and are provided with retaining means for securely holding the finger at any desired position. Each finger comprises a strip 20 of thin material, preferably metal, which may be pressed and formed to provide an opening, through which the gripper bar is adapted to slide. I prefer to construct each finger as shown in Figs. f to 6 from a metal stamping and to fold a portion of the metal backwardly upon itself, and securely fasten it in such folded position. 7

In Fig. 4 I have shown a blank form having the projecting finger 20 and the body portion 21. In the body portion suitable notches as at 22 are cut toprovide laterally extending tongues 23, and at one end of the body portion I'p'rovide notches 24, together with a projecting strip or tongue 25. Aligned with the tongue 25 and at the other end of the body portion I provide a notch 26, which extends through the metal and'is of a size sufficient to permit the tongue 25 to be inserted therethrough. It will be noted that the various notches andtongues may be stamped in one operation from a blank form, and that the blank may be folded as shown in Figs. 5 and 6 to form a complete finger. During the folding process,

the tongues 23 are bent inwardly at an angle that is substantially equal to the face angle of the saw-teeth serrations on the gripper bar.

In Fig. 6 the tongue 25'is shown as extending through the body portion, and is riveted to the other side thereof. The point at which the tongue is riveted is so positioned with relation to the "arcuate portions '27 that the cross-sectional area between notch 26 and each arcuate portion, is substantially equal to the cross sectional area of the finger 20. This, of course, provides strength at a point where the greatest strain is liable tobe exerted upon the projecting member.

The construction of a slidable finger from a one-piece form permits this device to be uickly constructed and cheaply assembled.

he-projectingfingers may be tempered so against the gripper bar, I prefer to use a leaf spring 28, which extends from one end of the finger to the other end thereof through the notches'2ei. The elasticity of the spring is suflicient to retain it in position without the use of other retaining means, such as rivets. We prefer to position the spring in the finger by having the ends 29 thereof, in abutting engagement with the surface 12 of the bar, and by having the center position thereof intertwined between the notches 24;.

In operation a pair'of gripper bars are secured to the platen, with the smooth sides 12 facing inwardly. Thes'e bars are positioned apart an amount sufficient to permit a sheet 15 to be inserted between them, and then a suitable number of fingers are slipped over the bar and adjusted into position between the type. Various lengths of fingers are provided to correspond with the type used, and with the size of sheet to be retained. To adjust the fingers, the operator 1 manually presses the body portion thereof, against the tension in the spring'28, until the tongues 23 clear the points of the serrations 13. Then the fingers may be slid lengthwise of the bar and the pressure released, whereupon'the tongues will again engage the serrations and be securely held against the bar. V 7

From the foregoing description it will be seen that I have provided a gripper which is capable of being adjusted to'a fine degree of accuracy, and efliciently holds the paper against the platen; and which is equipped with a form of bar that enables one to opcrate. a press without endangering'either detents disposed in opposite directions and in engagement with the-serrated portion of I the bar, said detents being disposed adjacent the ends of the body portion and formed integral therewith, said body portion having notches adjacent the smooth side of the bar, and a spring intertwined between said notches for holdin the detents in engagement with the bar, sai spring having the ends thereof in abutting engagement with said bar.

2.1n'oombination, a gripper bar having a series of sawtooth serrations along one side thereof, a finger slidably mounted on the bar, said finger comprising a one-piece construction having a body portion and an extended portion, the body portion having detents integral therewith and dis osed in opposite directions from the ends t ereof, a spring interwoven in the body portion in such. manner that the ends of the spring are in sliding contact with the bar, whereby both of said detents are held with approxiigiately equal force in engagement with said ar. v

3. In combination, a gripper bar having serrations along one side thereof, a member comprising a one-piece structure having a portion thereof embracing the bar, and having two inwardly inclined and oppositely disposed detents arranged to engage one side of said bar, and having two approximately parallel apertures adjacent the other side of said bar, and a spring interwoven through said apertures in such manner that the middle portion of the spring is on the exterior part of the body portion, while the ends of the spring are on the interior part thereof,

whereby the points of contact between the spring'and bar are substantially in a plane with the points of engagement between the detents and bar, said plane being substantially normal to the plane of the bar.

4. In combination, a gripper bar havin saw-tooth serrations on one side thereof, an a smooth surface on the other side thereof, a gripper finger, said finger having a onepiece body portion embracing the bar, said body portion being bent inwardly to form a detent, and a spring carried by the body portion for normally urging the detent into engagement with the bar, said spring being retained in position by being interwoven in the body portion of said finger.

In testimony whereof, I hereunto aflix my signature.

ROBERT T. SNELL.

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