US1628768A - Gripper-tensioning mechanism for presses - Google Patents

Description

May 17 1927 F. s. ENGLISH GHANISM FOR PRESSES GRI PPER TENS IONING ME Filed May 6. 1925 33% L ww Patented May 17, 1927.

UNITED STATES FRED S. ENGLISH, OF NEW LONDON, CONNECTICUT.

GRIPPER-TENSIONING MECHANISM FOR PRESSES.

Application led May 6, 1925, Serial No. 28,354.

In the co-pending application of Thomas L. Perry and myself there shown and described a gripper tensioning mechanism for presses and the object of the present invention is to secure the same or similar results to those secured through the mechanism described in `said co-pending a plication, but through different instrumenta ities.

The present invention relates to mechanism for holdingY the grippers upon the sheet and they same is adapted for use in printing presses as well as cutting and creasing presses. In `present practice it is customary to provide a shaft which is carried b' the impression cylinder of a press and on tfile shaft are mounted a series of curved members, commonly called grippers, which impinge against the forward edge of the sheet which is to be printed or cut and creased, pressing the edge of the sheet against the forward or leading edge of the impression portion of the cylinder. Generally, the grippers are closed on the sheet by spring action and they are opened by means of a cam through a lever action which turns the gripper shaft. When the grippers first act on the sheet the latter is stationary and the inertia of the sheet must be overcome ractically instantly.` This places a heavy garden upon thev grippers when the sheet is first started, and requires much greater holding force than is afterwards necessaryto carry the sheet around With'the impression cylinder. If there is any slippage etween the sheet and the grippers while the sheet is starting from the deadstop position, this will affect the register ofthe press. The object of the resent invention is to rovide means for p acing an additional hol ing resistance upon the grippersvvhile the inertia of the sheet is being overcome, and this holding action may be continued during any portion of the revolution of the cylinder, although in practice it has vbeen found necessary to apply this additional pressure only duringthe starting of the sheet and for a short period thereafter. If the ordinary springs usually employed for closing the gri pers upon the sheet are made sufficiently stili) to provide the extra 'pressure required during the starting of the sheet, there is difficulty in opening the grippers to deliver or take the sheet and the gripper operating mechanismin such case is subject to rapid wear. In thepresent case I have shown means separate from the ordinary 1 mans for holding the grippcrs, which may place an additional or auxiliary pressure upon the grippcrs at the moment the latter are closed upon the sheet. Another object of my invention is to accomplish the above inentioned results with the fewest number of parts operating in a simple manner.

In the drawings forming part of this application,

Figure l is an end elevation of the cylinder of a printing press or cutting and creasing press, showing the usual mechanism einployed for operating the grippers,

Figure 2 is an end elevation, on a larger scale, showing a portion of my improved device for applying auxiliary pressure to the grippers, and y Figure 3 is a front vievv of the same parts.

In the drawings 1 indicates the impression cylinder of the press and it is to be understood that this may be the impression cylinder of a printing press, a cutting and creasing press, or any other form of press, or it may constitute a transfer cylinder of a, press, the invention being adaptable to any orm of press in which grippers are used to take the sheet. I have also shown one end of the feed board 2 along which sheets are individually fed to the cylinder l. There is mounted in the bearings 14 on the cylinder the ordinarygripper shaft 4 to which are secured the grippers 6 which engage the leading edge of the sheet and press against the leadin edge of the impression portion of the cy inder 1. At the moment these grippers first engage the sheet the latter is at rest and momentarily the grippers must overcome the inertia of the sheet and must press on the same tightly for that purpose.

The ordinary device for rocking the shaft in order to close the grippers, consists of a crank 15 which is secured to the shaft 4 outside of the cylinder. On one end of this crank there is an anti-friction roller 5 Which is acted upon by a `cam 3 secured to a stationary portion of the frame of the machine. The roller 5 is held against the cam 3 by means of a compression spring l2 which sur-V rounds the spring rod 1l. One end of the spring presses againstl the spring step 13 While the other end acts against a collar on the rod 11 and the latter is pivoted at 9 to a segment 8 which rocks on a `stud 10 fixed y to a bracket 16 in the cylinder. The seg- `ment 8 has teeth which mesh With the teeth of a gear 7 secured to the gripper shaft 4.

The compression action of the spring 12 acting through the rod 11, segment 8, and the gear 7, serves to rotate the shaft Ll, thereby pressing the roller 5 against the cani 3 and applying the torce for closing the grippers 6 upon the sheet. The mechanism thus described comprises the usual partsl eniployed for operating the grippers. To increasethe pressure of the 'spring 12 to exert enough force on the grippers to hold the sheet when the latter first starts, causes undue wear and breakage, 'especially at the point whereV theiroller 5 rst engages the cam 3f at 17-V andV the present mechanism is intendedito'ofter additional resistance to the grippers without increasing the strain on the parts at the time the grippers are being opened' by the cam 3. f

The. mechanism forL exerting this additional rpressure is shown in Figures 2 and 3. Preferablyion the end of the shaft #l opposite to# that on which the crank 15 is mounted, I attach the crank 18- in the lorm ot a lever arm and" itl extends backward, or approximately in a reverse direction 'from the crank 15 so that when the free end of the crank 15 moves downwardly, the free end of the crank 18 moves upwardly, and vice versa." In the freefend of the crank 18 there is an anti-friction roller 19 which is acted upon by a cam 20-which is secured to a stationary portion 21 ofthe press trame. There is a compression spring 22 which surrounds the spring rod' 23 and` one end oitl` this spring i pressesfupon the crank Zito rotate the shaft 4 ini'thefdirectioni necessary to close the gripp'ers. The spring 22' serves to assist or reinforcey the action ofthe spring 12 and itis part of the standard equipment now usedon`A large cylinder presses. At the moment theqgrippers are closed by the mechanism showininIiigure` 1 the roller19 comes into Contact with thecam 2() and this cam exerts a downward pressure upon the roller so that the grippersf are held against the sheet with greater resistance than that caused' by the'joint action of the springs 12 and V22;v After the sheet has been grippedA and mo'vedsoy that its inertia has been overcome the roller 19 will run oit the cani Q0 and thespring action` of the springs` 12 and 22 will'eXert sufficient pressure upon the grippers to hold the sheet during the remainder oit' the cycle of operatioiiiof the press.` By placing the auxiliary mechanism on the opposite end ofthe shaft 4 from the usualgripper closing mechanism the cam 2O may be inclined, to torce the roller 19 downy-wardly without breakage ot the parts as.

therewillbe a slight torque in the shaft Il.

y It is often necessary to open the grippersb i Swinging them entirelv within the evl- 2D C5 .l

inder fori'convenience in make ready, at which timethe roller 5 is entirely out of the path ofthecam 3. To do this the shaft run out of mesh with the gear 7 and the spring crank Q1 moves over beyond the dead center so that the spring 22 holds the grip pers in the wide open position.

From the above it will be apparent that I have provided simple and cliicient means for placing additional resistance upon the grippers momentarily at the time when the greatest pressure is required to overcome the inertia o it' the sheet. The active surface oit the cani 2O may be prolonged it desired but in most cases the auxiliary pressure will only be required for a briel" period, after which it is released by the cani Q0, so that by the time the grippers arrive at the point where thev are opened by the cani 3 there will be no greater strain on the opening mechanism than if thev present auxiliaryl pressing device were not employed.

Having described my invention, what I claim is:

1. In a press the combination oif a cylinder adapted to carry a sheet, :i shaft, grippers thereon, a lever arm on said shaft and a stationary cani tor operating said lever arm to press the grippers on the sheet at the moment the latter is taken and adapted to release said pressure immediately after the sheet has been taken.

2. Ina press the combination of a cylinder adapted to ca rry a sheet, a shaft, grippers thereon tor engaging and holding the sheet, lever arms onsaid shaft extending in opposite directions, spring means acting on one ot said arms for closing the grippers o n the sheet and means acting on the other ol" said arms for applying auxliary holding force to said grippers and adapted to release the saine beilore the grippers are opened.

3. In a press the combination of a cylinder adapted tol carry a sheet, a shaft. grippers thereon for engaging and holding the sheet, lever arms on said shaft extending in opposite directions, spring means acting on one ot .said arms for closing the grippeis on the sheet, and a cam actingon the` other of said arms tor applying holding force to said grippers. Y

1. In a press the combination oi avcylinder adapted to carry a sheet, a shalt, grippers thereon for engaging and holding the on one of said arms to close the grippers on the sheet and positive means acting on the other of said arms for holding the grippers cam will rook said shaft to hold the ipin closed position. pers upon the sheet, said roller being a. apt- 10 5. In a press the combination of n eylined to travel free of said cam when the gripder adapted to carry a sheet, a shaft, grippers are turned inside the cylinder.

pers thereon adapted to engage and hold the Signed at the city of New London, counsheet, u lever arm on said shaft having a ty of New London and State of Connecticut,

roller, a stationary cam with which said this lst day of May, '1925.

roller is adapted to engage whereby said FRED S. ENGLISH.

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