US2317993A - Sheet feeder - Google Patents

Description

May 4, 1943 c. w. HARRQLDv 2,317,993

SHEET FEEDER Filed March 15, 1941 5 Sheets-Sheet 1 T h/ F7' coMA/Ecrfa T0 05555/5601? 774,055

INV ENTO cH/amfsw Hama ATTORNEY 5 May 4, 1943 c. w. HARROLD SHEET FEEDER Filed March 15, 1941 5 Sheets-Sheet 2 NTOR.

. INVE CHHLES V HH ATTORNEY` May 4, 1943. c. w. HARROLD SHEET FEEDER Filed March 15. 1941 5 Sheets-Sheet 3 May 4, 1943.

C. W. HARROLD SHEET FEEDER Filed March l5, 1941 5 Sheets-Sheet 4 INVENTOR.

CHHRLES. M HHIWOLD BY 15M f/Wfw ATTORNEY5 -May 4, 1943.

C. W. HARROLD SHEET FEEDER Filed March 15, 1941 5 Sheets-Shea?l 5 N- INVENTOR www g wf #@Wwm@ BY fm #M1/Mz ATTORNEY Patented May 4, 1943 2,317,993 g SHEET FEEDER `Charles W. Harrold, University Heights, Ohio, assigner to Harris-Seybold-Potter Company, Cleveland, Ohio, a corporation oi Delaware Application March 15, 1941, Serial No. 383,576

30 Claims.

This invention relates to improvements in sheet feeders, and has reference particularly to novel mechanism for assuring the presentation of individual sheets at the proper time and in accurately registered position to a machine for operating upon them, such as a printing press.

In feeding relatively large sheets of paper or the like to a printing press it is customary to separate the sheets individually from a pile or other supply and convey them, either in fully separated condition or partially overlapping one another, along a feed board to a so-called registering position where they are stopped and brought into accurate registration with the press, from which position they are taken by the press and printed.

One method of registration which has found wide acceptance consists in bringing the sheet against two front stops or guides located on opposite sides of the center of the sheet and a side guide located along one side edge, this method being known as three-point register.

A difficulty experienced in carrying out this method is that sheets of heavy stock have a tendency to rebound after striking the stops and sheets of light or imsy stock have a tendency to buckle thus impairing the registration of the sheets. vThis is true even when the sheets are fed relatively slowly in overlapping relation, particularly in respect to the buckling of light stocks, because of the force exerted by the succeeding underlying sheets upon the foremost sheet when it engages the stops.

A further diiiiculty lies in the fact that the sheets may be improperly introduced into the conveying mechanism by the devices which separate them from the supply, so that they are slightly displaced forward or backward from their proper position or are slightly askew so that their front edges are not exactly at right angles to the direction of movement. Such irregularities must be eliminated before or during the registering operation. In particular, when lapped sheets are askew considerable registering time is consumed in straightening them owing to the slow travel of the sheets.

It also occasionally occurs that a sheet is so far out of position in the conveyor that it cannot be properly registered, or that no sheet is fed, and under such circumstances it is necessary to stop the printing operation and the feeding of sheets until the difliculty is corrected.

Various mechanisms have been contrived for overcoming these difficulties and carrying out the desired functions, but in most instances such mechanisms are only partially eective or are complicated and difficult to maintain in proper adjustment.

Accordingly one of the objects of this invention is to provide improved mechanism capable of performing some or all of the functions of slowing down, straightening, timing, registering and detecting the presence or absence of sheets being fed in succession to a printing or other machine.

Another object is to provide mechanism of the character stated which shall be simple in construction and eflicient and durable in operation.

Another object is to provide mechanism of the character stated lin which suction is 'employed for carrying out certain of the functions.

Another object is to provide a suction device especially adapted to slow a sheet down without itself having bodily movement, the slowingdown eiect being brought about by the gradual closing of the sucker orifice by the moving sheet.

A further object is to provide mechanism of the character stated which is especially adapted to operate upon sheets fed in lapped condition.

Still another object is to provide a device wherein suction is employed to slow down a moving sheet and the presence or absence of a sheet at the sucker mouth governs the continuance i or the discontinuance of the feeding operation.

Other objects and features of novelty will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which- Fig. 1 is a side elevational view of diagrammatic character with certain parts in vertical section, on the line l-I of Fig. 3, illustrating one embodiment of the invention.

Fig. 2 is a view similar to Fig. 1 but with the parts in a different position corresponding to a different point in the operating cycle.

Fig. 3 is a diagrammatic end elevational view partly in section on the line 3 3 of Fig. 1.

Fig. 4 is a fragmental plan view taken substantially on the line 4-4 of Fig. 1.

Fig. 5 is a fragmental detail sectional view taken substantially on the line 5-5 of Fig. 1.

Fig. 6 is a fragmental plan view showing an askew sheet as it approaches the registering position.

Figs. 7 and 8 are fragmental plan views simila to Fig. 4 illustrating the slowing down and registering of a sheet.

Fig. 9 is a vertical sectional view of the sucker head on the line 9-9 of Fig. 4.

Fig. 10 is a vertical sectional view of the sucker head on line Ill-I6 of Fig. 9.

Figs. 11, 12 and 13 are fragmental vertical sectional views illustrating modified forms of the invention.

In the drawings one end of a sheet conveyor of known design is illustrated comprising tapes I trained around a roller Il which is journaled in the frames F of the machine. Idler wheels I2 are employed to press the sheets against the tapes to insure proper forwarding action. The sheets, illustrated at Si, S2 and S3 are successively projected by the tapes onto a feed board or plate I3 and into engagement with the slow-down, registering and detecting devices hereafter to be described. Adjacent the forward end of the feed board is a fed-in device of known design comprising a shaft 4 upon which are mounted a plurality of arms I5 which support gripper contact bar |6 and gripper pivot shaft I1. Upon bar I6 are secured a plurality of sheet guides I8 and upon each end of pivot shaft I1 is an arm I9 which supports an end of gripper shaft which carries grippers 2 I.

'I'his feed-in device is operated in any suitable manner and by any suitable known mechanism to transfer `the sheets one at a time from the feed board I3 to the grippers (not shown) of a sheet handling cylinder 22 which may be the constantly rotating impression cylinder of a printing press. Preferably, however, the feed-in device is driven through one full rotation for each sheet fed thereto, and each cycle of rotation comprises a, stationary period during which the sheet is gripped by grippers 2 I, as shown in Fig. 2,

slows down to a stop preparatory to taking the next sheet. Mechanism of this kind is shown and described in Patent No. 2,192,908, issued March 12, 1940.

Preferably also the gripper shaft 20 and grippers 2| are actuated by known mechanism to swing about pivot shaft I1 within the path defined by bar I6 during the decelerating period so as to clear a sheet lying wholly or partly on the feed board I3. When the feed-in device is stopped shaft 20 and grippers 2| swing outward to their operative positions and the grippers are closed on the sheet.

In the preferred form of the invention, illus- 'trated in Figs. 1 to 10, inclusive, front registering guides 23 are provided which are mounted in the usual way upon a rock shaft 24 journaled in the frames F. Shaft 24 is oscillated by known mechanism not shown to move the guides 23 from their operative position shown in solid lines to their inoperative position shown in dotted lines in Fig. 2. At least two such guides 23 are used, one

on each side of the center of the machine, and I prefer to use four arranged in pairs as shown for purposes which will appear.

Between the members of each pair of guides 23 the front portion of the feed board I3 is notched out as at 24' to provide clearance for the upper ends of arms 25 which are rotatably mounted on rock shaft 26. Each arm 25 is bifurcated at its lower end and between the bifurcations and keyed to shaft 26 is a dog 21 having two parallel upstanding extensions 28, 29 between which a transverse wall portion 30 of arm 25 extends. A coil spring 3| carried in a hole in Wall 3D bears against extension 29 of dog 21 and an adjusting screw 32 in extension 28 of dog 21 bears against wall 30, thus yieldably and adjustably holding arm 25 in desired angular relation to shaft 26.

Rock shaft 26 is journaled in a plurality of arms 33, 34 that are fixed to a rigid cross brace 35 carried in frames F. Arm 34 is formed with an ear 36 that is drilled to receive loosely a rod 31 having an eye at its opposite end which rotatably receives a pin 38 carried in one arm of a bell crank lever 39 which is locked to shaft 26. Between the ear 36 and a collar 40 secured to rod 31 is a coil spring 4| which tends to rotate the bell crank lever 39 andv consequently the shaft 26 counter-clockwise as viewed in Figs. 1 and 2.

'I'he other arm ofbell crank lever 35iV carries a pin 42 which pivotally supports one end of a bar 43 whose other end is bifurcated and arranged to be slidably supported on block 44 loosely carried on rotating shaft 45. Bar 43 carries a stud 46 on which is mounted a roller 41 which runs on a cam 48 keyed to shaft 45, the roller being pressed against the cam by the action of spring 4|.

Shaft 45 is rotatably journaled in the frames F and is driven with one rotation for each sheet fed along the feed board I3. By means of the connections described, cam 48 therefore acts to swing arms 25 from operative position shown in Fig. 1 to inoperative position shown in Fig. 2 with similar periodicity.

Each arm 25 comprises at its upper end a block 49 formed on its under side to t in a groove 50 in the body of the arm and secured thereto by a screw 5I. Each block 49 is formed with an abutment 52 adapted to engage the front edges of the sheets and the upper surface of the block on the side of abutment 52 toward the feed board is arranged to lie substantially in the plane of the upper surface of feed board I3 when the block is in its operative position within the notches 24'.

Block 49 is provided with a hole 53 whose upper end is counterbored to receive a cylindrical plug 54 having a hole 55 connecting with hole 53. The upper end of plug 54 is formed into a series of slots 56 connecting with hole 55 and separated by bars 51. 'I'he cylindrical plug is arranged with one edge substantially coincident with abutment 52 and the slots 56 and bars 51 are arranged with their longest dimensions in the direction of movement of the sheets.

This slotted plug forms the mouth of a sheet gripping sucker, and while the particular formation of the same herein illustrated is preferred, it will be understood that variations in the shape and arrangement of the plug and passages therethrough may be adopted without departing from the spirit of the invention.

The body of arm 25 is provided with passage 58 which connects hole 53 with a passage 59 whosev outer end is sealed by plug 60 and whose inner end connects with a vertical passage 6|.

The lower end of passage 6| communicates with a transverse cylindrical chamber (see Fig. 5) which has two sections, first a section 62 arranged to receive a plunger 63, and second a section 64 arranged to receive a compression spring 65 surrounding the shank 66 of plunger 63. The spring 65 is confined between the shoulder 61 of plunger 63 and bottom 68 of chamber section 84 and tends to push plunger 63 outwardinto the position shown-in Fig. 5. Shank 66 extends with a close sliding fit through a bore 69 in the arm 25 and is threaded to receive a nut 10 which limits the extent of movement of the plunger to the left. Chamber 62 is of such depth as to permit plunger 63 to be drawn entirely into the chamber, movement in the latter direction being limited by shoulder 1|.

Arm 25 is further provided with a passage 12 leading from chamber 64 to a hollow elbow 13 to which is attached one end of a hose 14. The two hoses 14 leading from the two arms are connected to nipples 15 each of which communicates with a common chamber 16 in bracket 11 secured upon rock shaft 26 approximately centrally 0f the machine. Chamber 16 is connectedy by a single nipple 18 and hose 19 to a source of suction.

Although under some circumstances suction may be applied to the sucker mouths 54 continuously during operation of the machine, I prefer to control the suction so that it is applied only during those portions of the working cycle when the sucker mouth is required to grip a sheet. For this purpose I have illustrated diagrammaticaily a valve between hose 19 and a further hose connection 80 which leads to a source of suction such as a suction pump (not shown). This valve comprises a stationary casing 8| and rotary plug 82 therein having a suction passage 83 and a bleed pssage 84, the latter operating to connect opening 85 in casing 8| with the hose 19 leading to the sucker mouths when suction is cut off. The rotary plug 82 is turned through an angle by arm 86 connected to a rod 81 which is oscillated by a cam or other suitable mechanism (not shown) in time with the movements of arms 25. Preferably the timing is such that suction at the sucker mouths 54 is applied just before the front edge of each sheet moving along the feed board arrives at the sucker mouth and is cut off immediately after arms 25 have traveled toward their Fig. 2 position sufficiently to carry the sucker mouths 54 completely past the front guides 23.

From the preceding description it is apparent that when air is sumciently exhausted from chamber 62, 64, atmospheric pressure against the outer end of plunger 63 will force the latter completely within the chamber against the resistance of spring 65, and that under all other conditions plunger 63 will remain in its outer position. It

is also apparent that when suction is applied to i hose 19 the pressure condition within chamber 62, 64 depends upon whether or not the sucker mouth openings 56 are closed, or partially closed by a sheet.

The operation of the sheet separating and forwarding devices is controlled in accordance with the position of plunger 63 by mechanism of familiar character which will now be described briefly. A shaft 88 is provided which extends across the feeder and is oscillatably journaled in the frames F. This shaft corresponds to the trip control shaft commonly found in sheet feeding mechanism. Near one end of shaft 88 is keyed an arm 89 carrying a roller 90 which runs on a cam 9| keyed to the continuously rotating shaft 45, the roller being resiliently biased toward the cam by a spring 92 secured to arm 89 and to a pin 83 at a suitable point of thel frame. Cam 9| is formed to produce one oscillation of shaft 88 during each revolution of shaft 45 at a. time to be later indicated.

On shaft 88 arms 84 are keyed in proper position laterally of the machine to engage Dlungers 63, each of the arms being formed with a plunger engaging pad 85.

The position of shaft 88 at certain times in the cycle of operationv is utilized to control the operation of conveyor tapes l0 and preferably also other parts of the feeding mechanism including the devices by which the sheets are fed to the conveyer tapes l0. The means for accomplishing this result are not shown since they are well known (for example see U. S. Patent No. 2,200,367, dated May 14, 1940), and are not per se a part of this invention. The arrangement is such, however, that so long as oscillation of shaft 88 under the influence of cam 9| is permitted, tapes I0 and shaft 45 continue to operate, and when oscillation of shaft 88 is prevented, as by contact of one of the arms 94 with the corresponding plunger 63, the tapes |0 and shaft 45 are stopped, thus causing discontinuance of the feed of sheets to the grippers 2|.

It is to be noted that the formation of the sucker mouth is such that a moving sheet, as its front edge passes over the sucker, gradually closes the slots 56 to atmosphere while being effectively supported by the bars 51 against being drawn down into the sucker mouth. When the source of suction is connected, as by the valve 82, this gradual closing of the sucker mouths of the sheet causes a gradual exhaustion of air within the suction passages with the result that the sheet is pressed progressively more firmly against bars 51 and the surrounding supporting surfaces by atmospheric pressure. Such progressive increase in pressure in turn causes a progressive increase in the force of friction between the sheet and its supporting surfaces opposing the forces which are moving the sheet forward. Thereby the sheet is effectively slowed down as it moves across the sucker mouth toward the abutment 52. Preferably the degree of exhaustion obtainable when the sucker mouth is completely closed is chosen in relation to the forces tending to drive the sheet forward so that the sheet is very nearly but not quite completely slowed down to stationary condition at the time it reaches abutment 52, but this is not critical and the suction may under some conditions properly be strong enough to stop the sheet completely before it reaches the abutment, since for final registration the sheet is pulled forward against guides 23 by the suckers.

The slowing down action of the sucker mouths is illustrated in Fig. 7 wherein the dash lines indicate successive positions occupied by the front edge of a sheet S after successive equal intervals of time during which the sheet is being acted upon by the uniformly moving conveyor tapes |0. It is seen that the front edge of the sheet comes to rest against the abutment 52 only after the greater part of its momentum has been dissipated by the slowing down effect of the sucker mouth.

It is further to be noted that in the form illustrated the forwarding effect of the tapes I0 and any underlying sheets is transmitted to the foremost sheet by frictional contact and that therefore slippage may occur therebetween as the foremost sheet is slowed down by the sucker mouths. Such slippage is proper and in the case of stiff sheets is quite necessary. It is also apparent, however, that in the case of thin flexible sheets positive forwarding devices near the rear of the sheet could be employed and the sheet allowed to buckle in its termedlate regions to compensate for the slo g down of the front edge.

After the sheet is slowed down and stopped against abutments 52, suction is preferably maintained for a time and the arms 25 are relatively slowly moved toward inoperative position to draw the sheet gently up against the registering guides 23 and to draw the sucker mouths gradually off the sheet so as to urge the latter firmly but gently against the guides. This action is illustrated in Fig. 8 in which the slots 56 are shown partially uncovered by the withdrawal of the sucker mouth from the stationary sheet. It is seen that the sheet is first urged i'lrmly against the guides 23 by the full force of the friction between the sheet and the face of the sucker mouth and then held in that position with gradually decreasing force as the suction is broken by gradual uncovering of the sucker. 'I'his gradual release of the sheet is important since some deformation and strains exist in the sheet near the guides owing to its pressure thereagainst which if allowed to be suddenly corrected by the natural resiliency of the sheet may cause the sheet to spring back away from the guides. Such distortion and` strains in the sheet are also minimized by the arrangement of the guides 23 in pairs, one on each side of a sucker, as shown.

In addition to the simple slowing down of the front edge of the sheet, a sheet straightening action is effected by the arrangement of the two sucker mouths at some distance apart on opposite sides of the center of the sheet and by the proper positioning of the idler wheels I2.

As illustrated in Fig. 6 the wheels I2 are placed at a distance back from the abutments 52 such that they will act on a sheet to forward it substantially into contact with abutments 52 and will thereafter exert no appreciable forwarding action thereon. One wheel is placed on each Y side of the center of the sheet and preferably substantially in line with the corresponding abutment 52. 'I'he action of each wheel is independent of the other owing to the frictional connection between the sheet andthe tapes. Thus as atwisted sheet approaches the front end of the feed board one side engages its sucker and is slowed downthereby while the other side continues its more rapid forward movement until it in turn engages its sucker and is slowed down thereby. In this way a rapid squaring up of the sheet is attained.

The operation of the preferred form of the invention above described may be summarized as follows.

With arms 25 and guides 23 in the positions shown in Fig. l and suction on" so that air is being sucked in through slots 56, the tapes I0 and wheels I2 advance the foremost sheet into engagement with sucker mouths 54. As the sheet gradually covers slots 56, atmospheric pressure on the sheet causes increased frictional resistance to its forward travel with the result that the sheet slows down prior to reaching abutments 52, slippage meanwhile taking place between tapes I0 and the sheet. The sheet is also straightened as it is slowed down. 'Ihe closing of slots 56 causes plungers 83 to withdraw into chambers 62 out of the path of arms 84. At the moment when a properly advanced sheet would close slots 66 sufficiently to cause withdrawal of under roller causing spring 82 to tend to oscillate shaft 88 clockwise and raise arms 84 to their dotted line position. If both plungers 63 are withdrawn, arms 84 are free to move up and shaft 88 oscillates thus permitting the tapes I0 and shaft 45 to continue to run. If for any reason the sheet does not cover the slots 56, one or both of the plungers 63 remains extended and interferes with hte movement of arms 84 thus preventing oscillation of shaft 88 and causing the tapes I0 and shaft 45 to stop thus stopping further feeding of sheets. After a properly advanced sheet is stopped against abutments 52, arms 25 move in the direction oflsheet travel under the influence of cam 48, such movement being slow in comparison to the speed of the sheet along board I3, to bring the sheet against front guides 23. Arms 25 continue their forward movement. the sheet meanwhile being held on the feed board by guides 23. After sucker mouths 54 have been drawn of! the sheet suction is cut off by valve 82, and arms 25 continue their movement to inoperative position shown in Fig. 2. As soon as the sheet has been properly laid against front guides 23 and the sucker mouths 54 have been withdrawn the sheet is side registered preparatory to being taken into the machine. Grippers 2| then close upon the sheet, as in Fig. 2, guides 23 thereafter move down out of the path of the sheet, and shaft I4 rotates to carry the sheet onto cylinder 22. Immediately after the tail of the sheet passes off feed board I3, arms 25 and guides 23 are returned to their operative positions to receive the next sheet and the operations are repeated.

In a modication of the invention shown in Fig. 1l, two sucker mouths I0| (corresponding to mouths 54 in the preferred form of Figs. 1 to 10) are carried by two arms |02 mounted on an oscillating shaft |03 close under the feed board. Abutments |04 are provided. corresponding to abutments 52. Sucker mouths |0I are connected by tubes |05 and hoses |06 to a common source of controlled suction. This form operates in a manner similar to the form of Figs. 1 to 10 except as follows:

When a sheet has been advanced over the slowing down suckers I 0| and into contact with abutments |04, suction is then cut off from the suckers, arms |02 are lowered to carry abutments |04 below the level of feed board I3 and the sheet is advanced into contact with guides 23 -by the conveyor tapes. Preferably abutments |04 stop the sheet only a slight distance from guides 23 so that the sheet acquires very little momentum before reaching the latter guides.

In another form of the invention, -illustrated in Fig. l2 only one set of sheet stops is employed. Front registering guides |01, preferably two in number, are used and preliminary stops are omitted. Guides |0'I are formed integrally with guide brackets |08 which also are provided with suction passages |09 leading from the sucker mouths I I 0 (similar to sucker mouths 54) to tubes I II which are connected by hose connections I I2 to a controlled source of suction. In the operation of this form the sheet is fed by the conveyor tapes down table I3 and across sucker mouths I I0 with suction on and substantially into contact with guides |01, the sheet being slowed down by the suction effect as it approaches said guides. At the proper moment in the cycle after the sheet is stopped suction is cut off and the sheet allowed to adjust itself against guides |01, meanwhile beplungers 63 the low part of cam 9| begins to pass 76 ing urged forward to some extent by the conveyor tapes. At the proper time the grippers 2I grip the registered sheet and shaft 24 is oscillated to drop guides I 01 out of the way.

In still another form illustrated in Fig. 13 the sucker mouths 54 are nxed in relation to the feed board II3 and preferably are a slight distance up the feed board fromfront guides 23 as shown. The sucker mouths 54 are supportedin blocks I I4 held by screws -II5 to the lbottom of the feed board. Tubes I I6 and hose connections III connect the source of suction to the suckers. In this form the sheets are slowed down, straightened without the use of preliminary stops or abutments such as 52 or |04. At the proper moment in the cycle after the sheet is stopped, suction is cut of and the sheet is advanced through a slight distance to guides 2-3 by the conveyor tapes.

When the invention is employed in connection with sheets fed in lapped relation it is preferred in some cases, as when very long sheets are to be fed, to return arms 25 and guides 23 to their operative positions and to advance the next sheet into engagement therewith while the tail portion of the sheet being transferred to cylinder 22 still partly covers said next sheet. This condition is illustrated in dash lines in Fig. 1 wherein SO is the sheet being transferred. It will .be noted that the arrangement and location of the sucker mouths 54, abutments 52 and guides 23 underneath the stream of underlapped sheets is especially adapted to provide effective operation on the forward edges of the sheets while they are still partly covered. The arrangement of the rotary transfer device herein described on the opposite side of the sheet path likewise contributes to this result. It is within the invention also to arrange the devices so that each sheet is acted upon by the suckers 54 while covered by the preceding sheet and is drawn up against the guides 23 only after being uncovered.

Having thus described my invention, I claim:

1. In sheet feeding mechanism, a feed board adapted to support a sheet, a sucker adjacent the front end of said feed board adapted to act upon the front portion of a sheet for slowing it down, means for advancing a sheet along said feed board to carry its front edge across the mouth of said sucker while suction is maintained therein to thereby close the sucker and cause the same to act upon the sheet, and means for cutting oif suction thereafter to permit registration of the sheet.

2. In sheet feeding mechanism, a feed board adapted to support a sheet, a sucker adjacent the front end of said feed board adapted to act upon the front portion of a sheet, and means for advancing a sheet along said feed board to carry its front edge across the mouth of said sucker while suction is maintained therein to thereby close the sucker and cause the same to act upon the sheet, the advancing sheet being slowed down during psage of its front edge across said mouth by frictional resistance applied to the surface thereof by virtue of the suction in said sucker.

3. In sheet feeding mechanism, a feed board adapted to support a sheet in a position of rest, a sucker adjacent the front end of said feed board ,adapted while stationary relative to the feed board to act upon the front portion of a sheet, and means for advancing a sheet along said feed board toward said position of rest to carry its front edge across the mouth of said sucker while said sucker is substantially stationary and while suction is maintained therein to thereby close vand stopped entirely by the suction effect and sheet being slowed down during passage of its front edge across said mouth by frictional resistance applied to the surface thereof by |virtue of the suction in said sucker.

4. In sheet feeding mechanism, a feed board adapted to supporta sheet, two suckers adjacent the frontend of said feed board Vone on each side of the center of the feed board adapted to act upon the front portion of a sheet for slowing it down, means for advancing a sheet along said feed board to*y carry its front edge 'across the mouths of said suckers while suction is maintained therein to thereby close said suckers and cause the same to act upon the sheet, and means for cutting oif suction thereafter to permit registration of the sheet.

5. In sheet feeding mechanism, a feed board for supporting a sheet, a sheet registering guide adjacent the front endt of said feed board, means for advancing a sheet along said feed board toward said guide, and a sucker associated with said guide adapted to have its mouth gradually closed by the front portion of an advancing sheet as it approaches said guide, suction being maintained in said sucker during the closing thereof, the sheet being slowed down by frictional resistance induced by the suction prior to reaching said guide.

6. In sheet feeding mechanism, a feed board for supporting a sheet, two sheet registering guides adjacent the front end of said feed board one on each side of the center of the feed board, means for advancing a sheet along said feed board toward said guides, and a sucker associated with each of said guides adapted to have its mouth gradually closed by the front portion of an advancing sheet as it approaches said guides, suction being maintained in said suckers during closing of the mouths thereof, each side of the sheet being slowed down substantially independently of the other side by frictional resistance induced by said suction prior to reaching the guide on that side.

7. In sheet feeding mechanism, a feed board for supporting a sheet, two sheet registering guides one on each side of the center of the feed board, means for advancing a sheet along said feed board toward said guides, two movable suckers one associated with each of said guides. and means for moving said suckers into and out of operative position and for maintaining the same substantially stationary for a time in operative position, said suckers being adapted in op.

erative position to have their mouths gradually closed by an advancing sheet as it approaches said guides, suction being maintained during the closing of said mouths, whereby the sheet is slowed down by frictional resistance as it approaches said guides.

8. In a sheet feeder, front registering guides, suction slow-down means adapted to act upon the forward edge of a sheet as it approaches the front guides, and trip means controlled by the suction condition in said slow-down means for actuation of the trip in the event that a sheet fails to arrive at the slow-down means at the proper time.

9. Ina sheet feeder, front registering guides,

' sucker means having a mouth adjacent the sheet path rearwardly of said guides, said means being adapted to slow down a sheet as the front edge thereof travels across the sucker mouth toward said guides, and trip means controlled by the suction condition in said slow-down means for the sucker mouth by the sheet, the advancing actuation of the trip in the event that a sheet fails to close the sucker mouth at the proper time.

10. In a sheet feeder, front registering guides, a sucker beneath the sheet path rearwardly of said guides adapted to slow down a sheet as the front edge thereof passes over the sucker toward the guides, and trip means controlled by the suction condition in said sucker for actuation o f the trip in the event that a sheet fails to cover said sucker at the proper time.

11. In a sheet feeder, a feed board adapted to support a sheet, front registering guides, a sucker mounted below the sheet path having a sucker mouth adjacent said path, whereby the sucker mouth is closed by a sheet advancing toward said guides, and means for moving the sucker forward beyond said guides, whereby the guides strip the sheet from the sucker.

12. In a sheet feeder, front registering guides, means for moving said guides into and out of the sheet path, a sucker arm mounted below the sheet path having a sucker mouth adjacent said path, said sucker mouth being adapted to slow down a sheet as it passes thereover in a forward direction, trip means controlled by the suction condition in said slow-down means for actuation of the trip in the event that a sheet fails to close the sucker mouth at the proper time, and means for moving the sucker arm forward beyond said front guides whereby the guides strip the sheet from the sucker.

13. In a sheet feeding machine, a sheet de-` tectJr comprising a sucker having a sucker mouth adjacent the path of travel of the sheets, a suction line connected with said sucker, means for making suction effective therein as a sheet approaches the sucker, said sucker mouth being adapted to be closed by the front edge of the sheet as it passes thereover, and means controlled by the pressure condition in said line for tripping the machine when a sheet fails to close said sucker mouth at the proper time.

14. In a sheet feeding machine, a sheet detector comprising a sucker having a sucker mouth adjacent the path of travel of the sheets, a suction line connected with said sucker, means for making suction eiective therein as a sheet approaches the sucker, said sucker mouth being adapted to be closed by the front edge of the sheet as it passes thereover, means for tripping the machine effective at a predetermined point in each cycle, and means made effective by the building up of suction in the line as the sheet closes the suction mouth for disabling said tripping means.

15. In a sheet feeding machine, sheet slowdown means comprising a sucker adjacent the sheet path having a sucker mouth elongated in the direction of travel of the sheets, and means for making suction effective in said sucker mouth as the front edge of each sheet approaches the sucker, whereby the sucker mouth is closed gradually by the sheet itself and the speed of travel of the sheet is decreased.

16. In a sheet feeding machine, sheet slowdown means comprising a sucker adjacent the sheet path, said sucker having a mouth with an effective longitudinal dimension greater than its effective transverse dimension, and means for making suction effective in said sucker mouth as the front edge of the sheet approaches the sucker, whereby the sucker mouth is closed gradually by the sheet itself and the speed of travel of the sheet is decreased.

17. In sheet lfeeding mechanism, a feed board adapted to support a sheet, a pair of sheet registering guides adjacent the fron-t end of said feed board one on each side of the center thereof, a preliminary sheet stop associated with each of said guides adapted to occupy a position slightly to the rear of said guides, means for advancing a sheet along said feed board toward said stops, a sucker associated with each of said stops adapted to have its mouth graduauy closed by the front portion of an advancing sheet as it approaches said stops, suction being maintained in said sucker during the closing thereof, each side of the sheet being slowed down substantially independently of the other side thereof by frictional resistance induced by the suction prior to reaching the guide on that side, and means for simultaneously withdrawing said stops from operative position in timed relation to the rest of the feeding mechanism after a sheet has reached both of said stops for permitting the sheet to advance to said sheet registering guides.

18. In sheet feeding mechanism, a feed board adapted to support a sheet, a sheet registering guide adjacent the front end of said feed board, a preliminary sheet stop adapted to occupy a position slightly to the rear of said guide, means for advancing a sheet along said feed board toward said stop, a sucker associated with said stop adapted to have its mouth gradually closed by the front portion of an advancing sheet as it approaches said stop. suction being maintained in said sucker during the closing thereof, the sheet being slowed down by frictional resistance induced by the suction prior to reaching said stop, and means for withdrawing said stop from operative position in timed relation to the rest of the feeding mechanism for permitting the sheet to advance to said sheet registering guide.

19. In sheet feeding mechanism, a feed board adapted ,to support a sheet, a sucker adjacent the front end of said feed board adapted to act upon the front portion of a sheet, and means including a conveyor tape and associated sheet hold-down Wheel substantially in line with said sucker for advancing a sheet by frictionally applied force along said feed board to carry the front edge of the sheet across the mouth of said sucker Iwhile suction is maintained therein to thereby close the sucker and cause the same to slow down the sheet.

20. In sheet feeding mechanism, a feed board adapted to support a sheet, two sheet registering guides adjacent the front end of said feed board one on each side of the center of the feed board, means including a pair of conveyor tapes and associated sheet hold-down wheels for advancing a sheet by frictionally applied force along said feed board toward said guides, each tape being arranged substantially in line with one of said guides and the wheel associated therewith being located slightly more than the length of a sheet away from the corresponding guide, and a sucker associated with each of said guides adapted to have its mouth gradually closed by the front portion of a sheet as it approaches said guides, suc; tion being maintained in said suckers during closing of the mouths thereof to thereby slow the sheet down, each side of the sheet being acted upon substantially independently of the other side by said advancing means and said suckers `whereby the sheet is straightened and slowed down prior to reaching said guides.

21. 'I'he method of slowing down a moving sheet comprising the step of applying to the surface of the sheet a gradually increasing frictional force opposing the movement of the sheet, the application of said force being controlled in accordance with the position of a transverse edge of said moving sheet.

22. The method of slowing down a moving sheet comprising the step of applying to the surface of the front portion of the sheet a gradually increasing frictional force opposing the movement of the sheet, the application of said force being controlled in accordance with the position of the front edge of said moving sheet.

23. The method of slowing down a moving sheet comprising the step of applying to the surface of the front portion of the sheet a gradually increasing frictional force opposite in direction to the movement of the sheet, the rate of increase of said force being controlled in accordance with the travel of the sheet after the slowing down begins.

l24. The method of slowing down and straightening a moving sheet comprising the step of applying to the surface of the front portion of the sheet at points on opposite sides of the center thereof a gradually increasing frictional force opposing the movement of the sheet, the application of said force at each of said points being controlled in accordance with the position of that portion of the front edge of said moving sheet adjacent the corresponding point.

25. The method of slowing down and straightening a moving sheet comprising the step of applying to the surface of the front portion of the sheet at points on opposite sides of the center thereof a gradually increasing frictiional force opposing the movement of the sheet, the rate of increase of said force at each of said points being controlled in accordance with the travel of that portion of the front edge of said moving sheet which is adjacent the corresponding point after the slowing down begins.

26. The method of advancing sheets toward the front guides of a printing press or other machine comprising applying frictional force to the surface of a sheet to advance the same, appfying to the surface of the front portion of the sheet a gradually increasing frictional force opposing said advancing force to slow the sheet down, the

. application of said opposing force being controlled the surface of the front portion of the sheet agradually increasing frictional force opposing said advancing force to slow the sheet down, the application of said opposing force being controlled in accordance with the position of the front edge of said 'moving sheet, stopping the `sheet after it is slowed down, and thereafter applying frictional force to the surface of the sheet to advance the sheet at reduced speed into engagement with said guides. y

28. The method of advancing a sheet to the front guides of a printing press or other machine comprising advancing the sheet toward the guides, applying to the surface of the front portion of the advancing sheet a gradually increasing frictional force opposing the movement of the sheet to slow the latter down prior to reaching said guides, advancing the sheet at reduced speed into engagement with said guides, and holding the sheet in engagement with said guides for a time by gradually decreasing frictional force applied Y in the direction of sheet advance to the front portion of the sheet.

29. 'I'he method as claimed in claim 28 wherein is also included the step of stopping the sheet for a time after it is slowed down4 and before it is advanced into engagement with the guides.

30. The method as claimed in claim 28 wherein are included the steps of controlling said increasing and decreasing frictional forces in accordance with the position of the front edge of the sheet.

CHARLES W. HARROLD.

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