US2856188A

US2856188A - Sheet feeding mechanism

Info

Publication number: US2856188A
Application number: US597431A
Authority: US
Inventors: Crittenden Charles Bruce
Original assignee: Harris Intertype Corp
Current assignee: Harris Corp
Priority date: 1956-07-12
Filing date: 1956-07-12
Publication date: 1958-10-14
Anticipated expiration: 1975-10-14

Description

0d. 14, 1958 c. B. CRITTENDEN 2,856,188

SHEET FEEDING MECHANISM Filed July 12, 1956 migmwl INVENTOR.

CHA BLES BRUCE CRITTENDEN BY M AGENT United States Patent snEEr FEEDING MECHANISM Charles Bruce Crittenden, (Shagrin Falls, Ohio, assignor t Harris-lntertype Qorporation, Cleveland, Ohio, a corporation of Delaware Application July 12, 1956, Serial No. 597,431

8 Claims. (til. 271--53) This invention relates generally to feed rolls for feeding sheet material to a printing press or other sheet handling machine, and particularly to means for stopping rotation of freely rotatable feed rolls to prevent their marking or burnishing of a sheet to be fed as they move into engagement with the sheet prior to feeding it to the press.

In conventional feed roll type printing presses, sheets are fed one at a time against front stops which bring them to rest and front register them. After front registration has been completed, each sheet is then gripped and pulled transverse to the direction of sheet travel against a side gauge for side registration. Next, a plurality of sets of feed rolls grip the sheet along its front edge from opposite sides and drive it forward at high speed to crowd the front edge against gauge pins on a cylinder of the press for a final front registration. Grippers on the cylinder then close on the registered edge to carry it into the press, and the feed rolls release the sheet. Each set of feed rolls comprises a driving roll on a fixed axis and a freely rotatable roll movable into and out of sheet engagement. The driven rolls may be located above the sheet path and the driving rolls below, or vice versa.

In high speed presses the time interval between disengagement of the freely rotating rolls from one sheet and engagement with the next is relatively short. This creates a problem of marking of sheets since the high speed freely rotatable rolls usually continue spinning freely while they are out of engagement with sheets. In addition to this, the freely spinning rolls tend to overcrowd and thus buckle the sheets against the front stops. Such overcrowding is undesirable and is especially noticeable when printing relatively flirnsy stock.

The disadvantages of these conventional feeders is more pronounced when the free rolls contact sheets from above, because the upper side of the sheets is normally the side which is printed. This means that any marks made by the rolls will appear on the printed side. Furthermore, where it is desired to print more colors than the press is equipped to print on one pass therethrough, then the sheets must be fed through an additional time or times. Unless the ink has completely dried or set, the free spinning of the rolls causes smearing of the prior printing.

When printing is being done on both sides of a sheet on a prior art press, free rolls below the sheet path will smear at least that side of the sheet and will have previously marked what becomes the top side of the sheet on the second pass through the press.

The principal object of the invention therefore is to prevent marking, burnishing, and smearing of sheets when they are engaged by freely rotating feed rolls.

Another object is to prevent the feed rolls from buckling or overcrowding flimsy sheets against front stops.

ice

Still another object of the invention is to provide braking means for stopping rotation of the freely rotatable feed rolls while out of engagement with sheets.

A further object is to provide that such braking means be made to engage the periphery of each free roll and be of such material so as to effectively wipe clean any dirt or ink from the roll.

Another object of the invention is to provide individual braking means for each of the freely rotatable rolls, means also being provided for adjusting each separately.

Other objects and advantages will appear from the following description, in which reference is had to the accompanying drawings.

In the drawings:

Figure 1 is a simplified elevational view illustrating a pair of feed rolls of the invention feeding a sheet of paper to a printing press cylinder.

Figure 2 is a fragmentary elevational view on a smaller scale looking in the direction of sheet feed showing conventional sets of feed rolls, and further illustrating braking means for stopping rotation of the freely rotatable rolls when out of engagement with sheets.

Figure 3 is an enlarged detailed view illustrating the operative parts and the braking means of the invention with which the freely rotatable rolls cooperate.

Feed rolls such as those illustrated at 10 and 11 in Fig. 1 are arranged in a plurality of sets or pairs, the rolls it cooperating with rolls ll. to grip sheets to be fed. The feed roll it of each set is freely rotatable and is movable into and out of engagement with each sheet. The rolls 10 are driving rolls mounted on a fixed axis. The driving rolls fit together with the freely rotatable rolls it drive sheets forward to a printing press cylinder 16. The rolls it) are preferably mounted below a feed table 12 and the rolls ll above the table. However, the reverse of this may be true, the rolls it) being above and the rolls 11 below. Sheets S are individually fed from a sheet feeder (not shown) down the feed table 12 and are intercepted by a plurality of conventional front stops 13 which move into and out of the sheet path on a shaft 14. At the time a sheet moves to the front stops, the feed rolls lid and 11 are disengaged. After settling against the front stops 13 for a specified registration time, the sheets are side registered by the usual side registering mechanism (not shown) and then are pinched between the feed rolls it) and 11. The rolls 11 move from their dotted to their full line positions as shown in Fig. 1. At the time of engagement of the rolls lit with the sheet, the feed rolls it are stationary as will be described later.

Sheets are fed by the rolls to the printing cylinder 16, which may be an impression cylinder of the printing press or may be a feed cylinder which subsequently passes the sheets, after having taken them from the feed table, to the impression cylinder. The cylinder 16 carries a series of pivotal grippers 17 and gauge pins 18 which operate and perform their functions in the customary manner. While the grippers 17 are open, sheets are accelerated forward by the feed rolls iii and it against the gauge pins at a speed slightly higher than the speed of the cylinder 16 at that time. The grippers 17 then close on the leading edge of the sheet S, after which the feed rolls 11 move upwardly to discontinue their forwarding action on the sheet. When the rolls 11 leave contact with the sheet and move to their dotted line position in Fig. 1, they will be rotating :at high speed, which rotation would normally continue through the short interval before the rolls engage thenext sheet. In

order to overcome this rotation of the rolls 11 when they subsequently engage the next sheet, braking means 19 is provided for each roll, which means is effective only when the rolls 11 are out of engagement with the sheets. If the rolls 11 are rotating upon engagement with the next sheet, they will, in skidding on that sheet, leave marks along the leading edge. These marks are objectionable on high quality printed products. By stopping the spinning of the roll when it moves out of engagement with each sheet, the rolls 11 are stationary when they later engage the next sheet, and marking of the next sheet is thus prevented.

Referring now to Fig. 2 it will be seen that the feed rolls and 11 are mounted on

shafts

20 and 21 respectively, which shafts are journaled in side frames 22 and 23 of the printing press. The rolls lltl are fixed to shaft 20. On one end of the shaft 20 is mounted a gear 24 which is driven in timed relation from the press. The shaft 20 may be driven forward once for each sheet fed and have a stop period during which the feed rolls 11 move toward the rolls it) to grip a sheet. The shaft 2%) preferably is an oscillating shaft which, as viewed in Fig. 1, rotates from its rest position in a counterclockwise direction until the feed rolls 11 move out of engagement with the sheet and which then rotates in the reverse or clockwise direction until it again reaches its original position at which it comes to rest.

The shaft 21 on which the freely rotatable rolls 11 are carried is rocked once for each sheet by a reciprocating rod 25 which may be operated by any conventional means (not shown). The rod 25 is connected to a bracket 26 which is keyed to the shaft 21. For each roll 11, there is keyed to the shaft 21 a driving dog 27. As viewed in Fig. 3, the dog 27 has a radially projecting car 28, through which is threaded an adjusting screw 29. The screw passes through the ear 28 at right angles to the shaft 21.

Freely mounted on shaft 21 in cooperation with each driving dog 27 is a bracket 34) with an integral arm 31 which at its end carries a roll 11. The bracket 30 is bifurcated as at 32 and 34, and has its bifurcations straddling the ear 2%. One of the bifurcations 32 carries a button 33 against which the end of the screw 29 abuts. The bifurcation 34 has an enlarged hole 35 through which the other end of the screw 29 freely passes. A

spring 36 surrounds the screw 29 between the ear 28 and the bifurcation 34 to normally urge the bracket 36 in clockwise direction so as to cause the button 33 to engage the end of the screw. When the roll 11 is in its dotted line position, the end of the screw 29 is in engagement with the button 33. When the roll moves to its full line position, the roll engages the paper and pinches it. against the lower roll it When it does so, the roll lll isprevented from further travel toward the roll 10, but the shaft 21 continues turning a slight extent. Upon such further turning, the spring 36 is compressed a small amount and the end of the screw 29 which for merly was engaging the button 33 separates a predetermined extent from the button 33 according to the screw adjustment. The overtravel of the shaft 21 provides that the sheets are gripped by the rolls with pressure exerted through the dogs 27, the spring 36, and the brackets 30 carrying the rolls 11.

Upon movement away from the sheet, each roll 11 will remain in engagement with the sheet due to the compression of the spring 36 until the end of the screw 29 engages the button 33 and causes the dog 27 to positively move the bracket 30 in counterclockwise direction to lift the roll. 11 from the sheet. It will be seen therefore that the adjusting screw 29 has as a primary purpose the control of the time of opening of each feed roll. In normal operation, the screws 29 are set to provide simultaneous openings of the rolls.

Carried on a bar 37 fixedly mounted between side frames 22 and 23 and extending parallel to the

shafts

20 and 21 are a series of inverted studs 38, there being one for each of the freely rotatable rolls 11. The studs pass freely through the bar 37. The heads of the studs are engaged by the rolls when they move to their upper or dotted line positions. A spring 39 resiliently urges the head of each stud toward the roll 11 and away from the bar 37. A nut 40 is fastened to each stud 38 to adjust the relative position of the head of the stud with respect to its roll 11. The studs 38 are made of a material suitable for causing a braking action of the roll 11. Nylon has been found adequate for this purpose. However, the stud 38 may be of metal having a head of nylon or other suitable material.

The embodiment of the invention herein shown and described is to be regarded as illustrative only and it is to be understood that the invention is susceptible to variation, modification, and change within the spirit and scope of the claims.

Having described my invention, I claim:

1. In mechanism for feeding sheets lying at rest on a support to a sheet conveying device, a sheet driving roller located on one side of said support with its periphery in position to engage a sheet lying on the support, front stop means forward of said driving roller for temporarily arresting and front registering each sheet,

means intermittently driving the driving roller once for each sheet fed from a rest position to drive each sheet to said conveying device, a freely rotatable roller on the other side of said support, means moving said freely rotatable roller into engagement with a sheet at a preselected time while the driving roller is at rest to cooperate with the driving roller in gripping the sheet and out of engagement while the sheet and driving roller are moving, and means cooperating with said free.y rotatable roller only when out of engagement with the sheet to brake the free rotation of that roller and thereby cause it to come to rest prior to being lowered into engagement with the next sheet.

2. Mechanism according to claim 1 wherein said freely rotating roller is located above the sheet path and engages the upper surface 'of the sheet on said support.

3. Mechanism according to claim 2 wherein a plurality of said driving and freely rotatable rollers are provided in pairs and wherein one of said brake means is provided for each freely rotatable roller, said brake means being carried on a common support extending parallel to the axes of said rollers.

4. Mechanism according to claim 3 wherein each brake means is engageable with the periphery of its corresponding roller, and wherein each brake is provided with means for adjusting it relative to the periphery of its roller independently of the other brake means.

5. In mechanism for feeding sheets from a substantially horizontal feed table to a cylinder of a printing press or the like, a shaft below said table, a plurality of sheet driving rollers carried by said shaft, the periphery of each driving roller approximately coinciding with the top surface of said table, front stop means forward of said driving rollers for temporarily arresting and front registering each sheet, means for intermittently driving said driving rollers once for each sheet fed in a direc tion to feed sheets to said cylinder, a pivotal shaft above said table, a plurality of arms carried thereby, a freely rotatable roller on each of said arms, there being one of such-rollers cooperating with each sheet driving roller, means pivoting the pivotal shaft to move said freely rotatable rollers into engagement with a sheet while the driving rollers are at rest and out of engagement with the sheet while the driving rollers are moving, and means cooperating with said freely rotatable rollers only when out of engagement with a sheet for braking the rotation of each to insure that said freely rotatable rollers are at rest when they subsequently engage the next sheet.

6. Mechanism according to claim 5 wherein said hrak- References Cited in the file of this patent ing means comprises a member engageable vyith the pe- UNITED STATES PATENTS riphery of each freely rotatable roller when said rotatable rollers are in their upper positions. 19,951 Storck 1936 7. Mechanism according to claim 6 wherein each brak- 5 497,745 Bascom May 1893 ing member is individually adjustable. 752,382 Dexter 1904 8. Mechanism according to claim 6 wherein each brak- 1,023,869 Osborn 231 1912 ing member is resiliently urged against its correspond- 1,142,786 KnePPler "J 8,1915 1,889,353 Cross NOV. 29, 1932 ing freely rotatable roller.