US3658319A

US3658319A - Vacuum operated sheet feeding mechanism for newspaper inserter

Info

Publication number: US3658319A
Application number: US866230A
Authority: US
Inventors: Donald A Glaser
Original assignee: Didde Glaser Inc
Current assignee: DIDDE Corp; Diddle Glaser Inc
Priority date: 1969-10-14
Filing date: 1969-10-14
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25
Also published as: CH531975A; CA937594A; DE2050083A1; DE2050083C2; GB1312680A; FR2065374A5

Abstract

A feeding mechanism for single or multi-page sheets of flexible material combines a vacuum operated gripping assembly for initially gripping the lowermost sheet in an inclined stack thereof with a mechanical conveying unit for receiving the lowermost sheet from the assembly and delivering the same to a remote station therefrom. Grippers of the assembly are oscillated through an arcuate path during substantially vertical reciprocation of the carriage carrying the unit and the assembly such that a marginal portion of the sheet held by the grippers is bent away from the stack without moving the remaining portion of the sheet and introduced between opposed delivery elements of the unit for withdrawing the entire sheet from the stack. The grippers are retracted as the sheet is received between the elements, and a vacuum system associated with the assembly actuates the gripper in timed response to the reciprocation of the carriage and extension and retraction of the grippers.

Description

United States Patent Glaser [15 1 3,658,3W [451 Apr. 25, 1972 [22] Filed:

[54] VACUUM OPERATED, SHEET FEEDING MECHANISM FOR NEWSPAPER INSERTER [72] Inventor:

[73] Assignee: Diddle-Glaser, lnc., Emporia, Kans.

[21] Appl.No.: 866,230

Donald A. Glaser, Emporia, Kans.

' [52] US. Cl. ..271/29, 271/14, 27l/DlG. l

[51] lnt.Cl. 58] Field of Search...

..B65h 3/10, B65h 5/04 ..271/29, 27, 14, ll, 12

Primary Examiner-Even C. Blunk Assistant Examiner-Bruce H. Stoner, Jr. Attorney-Schmidt, Johnson, Hovey, Williams & Chase [57] ABSTRACT A feeding mechanism for single or inulti-page sheets of flexible material combines a vacuum operated gripping assembly for initially gripping the lowermost sheet in an inclined stack thereof with a mechanical conveying unit for receiving the lowermost sheet from the assembly and delivering the same to a remote station therefrom. Grippers of the assembly are oscillated through an arcuate path during substantially vertical reciprocation of the carriage carrying the unit and the assembly such that a marginal portion of the sheet held by the grippers is bent away from the stack without moving the remaining portion of the sheet and introduced between opposed delivery elements of the unit for withdrawing the entire sheet from the stack. The grippers are retracted as the sheet is received between the elements, and a vacuum system associated with the assembly actuates the gripper in timed response to the reciprocation of the carriage and extension and retraction of the grippers.

' 10 Claims, 13 Drawing Figures PATENTEDAPR 25 I972 SHEET 1 [1F 4 f7 TTORN E Y5.

VACUUM OPERATED SHEET FEEDING MECHANISM FOR NEWSPAPER INSERTER This invention relates to machines for handling sheets of flexible material and, more particularly, to a device for successively feeding single or multiple sheet newspaper sections from an inclined stack thereof to a delivery station or to an awaiting preopened newspaper for insertion thereinto.

A single edition of a metropolitan newspaper, especially a Sunday edition; generally consists of a number of different sections relating to various fields of interest such as world and local news, sports, social news, or the like. Several of the sections are generally printed in advance of the other sections and must thereafter be brought together from their individual printing locations and assembled in proper sequence to form a completed edition of the paper. A convenient means of accomplishing this final assembly of the edition has been effected by providing a number of side-by-side, interconnected assembling units which successively deliver the individual sections from stacks thereof at one end of the units into the awaiting, constantly moving open sections of the newspaper at the other end.

In addition to assembling the various sections of a newspaper edition, there has been an increasing need to provide machines of the above type which are adapted for stuffing the newspaper edition with special inserts, such as coupons, TV guide sections, and various types of advertisement sections. In many instances, inserts of this type are printed well in advance of printing of the main edition and are oftentimes printed in separate localities. Therefore, the problem of economically assembling the assorted sections and the inserts is once again presented. This problem is also apparent in the instance of a metropolitan newspaper having territorial sections which must be collated with common, city-wide sections at various localities around the city.

Newspaper sections present special handling problems in view of the multiple-page nature of each section and the common practice of conveniently storing the sections in upright stacks. Numerous engineering problems have been encountered in designing machines which will reliably remove successive sections from the top of such stacks. Bottom delivery systems are generally preferable since they eliminate the need for continual readjustment of the stack level as required in top delivery systems, but the weight of the stack above the lower end section thereof and the problem of access to the end section create problems with this system also.

Vacuum-operated feeder mechanisms have experienced some difficulties in coping with the problems of multiple pages, stack weight, and inaccessibility. Once contact has been made with the end section of the stack, sufficient vacuum pressure to the newspaper grippers must be supplied in order to insure that all pages of the section are controlled. Further, the system must be sufficiently strong to efiect withdrawal of the section from the stack against the weight of the sections thereabove. Tilting the stack has alleviated these problems to a certain degree, although not to a sufficient extent to provide reliable feeding and delivery of each section.

The above problems may be overcome by the utilization of a feeding system which employs a vacuum assembly to initially grip a marginal portion of the end section and, without actually withdrawing the section, to bend the gripped portion and introduce the same into a mechanical conveying unit for delivery to awaiting newspaper sections. Since the vacuum pressure is not utilized to shift the end section against the weight of the stack, high vacuum pressure is not necessary and the multiple page nature of the sections presents no problem.

Accordingly, it is an important object of the present invention to provide mechanism for feeding successive single or multiple sheet newspaper sections, inserts, or the like, from a stack thereof to a remote station which eliminates the necessity for sensitive high pressure vacuum systems or complex mechanical structure for effecting the initial withdrawal of each section from the stack.

Another important object of the invention is to provide a feeder incorporating a vacuum gripping assembly for initially gripping a marginal portion of the end section without shifting the section from the remainder of the stack, and for introducing the gripped portion between opposed rollers of a mechanical conveying unit to effect withdrawal of the section from the stack and subsequent delivery thereof with speed and reliability to a remotestation. In this respect, an important aim of the present invention is to provide positive gripping action effected by oscillating vacuum grippers which assume zero relative speed during initial engagement with the portion of the end section.

A further important object of the present invention is to provide a feeder as aforesaid which is designed such that a minimum of set-up time prior to operation thereof is required, and whose operating parameters may be readily adjusted in timed relationship to the rotation of a common drive shaft for all operating units of the feeder.

Yet another object of the instant invention is to provide a feeder as aforesaid which will reliably handle sheet material of various lengths, widths, and thicknesses.

In the drawings:

FIG. 1 is a side elevational view of a machine having a feeder which embodies the principles of the present invention, the delivery carriage thereof being shown at the beginning of an operating cycle in its raised position for the initial gripping of a sheet of flexible material such as a newspaper section;

FIG. 2 is a fragmentary, side elevational view of the feeder of FIG. 1 showing the delivery table halfway through an operating cycle and disposed in its lowered position after bending the portion of the end sheet and immediately preceding the withdrawal thereof from the stack;

FIG. 3 is a top plan view of the feeder with the operating parts thereof being shown at the beginning of an operating cycle corresponding to their positions in FIG. 1;

FIG. 4 is a fragmentary, side elevational view similar to FIG. 1 showing the opposite side of the feeder;

FIGS. 5 and 6 are enlarged, fragmentary, cross-sectional views taken substantially along lines 5-5 and 6-6 of FIG. 3;

FIG. 7 is an enlarged, exploded view showing the relationship between components of the valve apparatus for the vacuum lines;

FIG. 8 is an enlarged, fragmentary, cross-sectional view taken along line-8--8 of FIG. 3;

FIG. 9 is an enlarged, fragmentary, cross-sectional view taken along line 9-9 of FIG. 1;

' FIG. 10 is an enlarged, fragmentary, cross-sectional view taken along line 10-10 of FIG. 9;

FIG. 11 is an enlarged, fragmentary, cross-sectional view taken along line 1111 of FIG. 5;

FIG. 12 is an enlarged, fragmentary, cross-sectional view taken along line 12-12 of FIG. 5; and

FIG. 13 is an enlarged, fragmentary, cross-sectional view similar to FIG. 12, but showing the retractable gripper unit in its sheet-releasing position.

FIGS. 1 and 3 show a machine employing the feeding mechanism 20 which basically includes a receptacle unit 22 for receiving and supporting an inclined stack of newspaper sections or the like, a vacuum-operated gripping assembly 24 adjacent the receptacle unit 22 for initially gripping and bending a portion of the end newspaper section in the stack, a conveying unit 26 for receiving the gripped portion of the newspaper section from the gripping assembly 24 and withdrawing the section from the stack, and an inclined shelf 25 for receiving the sections delivered thereto by conveying unit 26. It is to be understood that the shelf 25 is representative of various alternative structures which could be provided in this location for use with feeder 20 such as conveyor structure for moving opened newspapers past feeder 20 or other support structure for reforming a stack of the fed newspaper sections after counting thereof or the like.

A pair of spaced,

upright support plates

28 and 30 having downwardly extending

slots

28a and 30a respectively are held apart by a transverse center brace 32, and as one function, serve to support the receptacle unit 22 at the supply end of the feeder 20. The receptacle unit 22 includes an inclined platform 34 spanning the distance between the

support plates

28 and 30 and rigidly mounted thereon by suitable bolt means (not shown). A support table 36 having a pair of depending side plates 38 is shiftably carried on the upper surface of the platform 34 by two sets of opposing rollers 40 on each of the side plates 38 which engage opposite surfaces of platform 34 (FIG. Each of the side plates 38 projects through an elongated slot 42 in platform 34 and is connected to a chain 44 trained over a sprocket 46 which is carried by a transverse shaft 48 joumaled by the

support plates

28 and 30. The other end of chain 44 hangs freely from sprocket 46, and the transverse shaft 48 projects through the support plate 30 and rigidly receives a worm gear 50 which intermeshes with a worm gear 52. Rotation of the gear 52 by the knob 54 at the outer end thereof regulates the level of the table 36 to properly position the stack supported thereon.

A pair of elongated, adjustable stack guides 56 engageable with the sides of the stack are individually supported by a pair of shafts 58 through the

support plates

28 and 30 respectively. A pair of bearings 60 rigid to the

plates

28 and 30 respectively, journal each of the shafts 58, and hand setscrews 62 through each of the bearings 60 are disposed for engagement with the corresponding shaft 58 to limit the lateral adjustment of the guides 56. Each of the guides 56 is provided with an upright rod 64 having an adjustable brace unit 66 adjacent the outer end thereof which is engageable with the end section of the stack to brace the upper margins thereof against untimely bending into the gripping assembly 24.

As earlier described, it is contemplated that machines employing feeders such as feeder may be arranged in a straight line in side-by-side relationship in the instance where several different sections or inserts are to be assembled into the final edition of the newspaper. Accordingly, with such an arrangement, it is convenient to drive the machines from a single prime mover and provide a common drive shaft or, altematively, individual shafts for each feeder which may be interconnected to form a common drive element, such that the operating cycles of the aligned feeders may be regulated in a timed relationship to one another. Thus, a power drive shaft 68 for feeder 20 extends between the

support plates

28 and 30 projecting outwardly from the latter and rigidly carrying a drive sprocket 70 on the end thereof. An endless drive chain 72 is trained about the drive sprocket 70, a large sprocket 74 on the outside of plate 30, and a third sprocket 76, the sprockets 74 and 76 thus being driven by the rotation of shaft 68 and, in turn, effecting the operation of the gripping assembly 24 and conveying unit 26 as will hereinafter be described. An idler sprocket 78 is carried by plate 30 and engages the chain 72 intermediate the sprockets 74 and 76.

As best seen in FIG. 9, the sprocket 74 is keyed to a shaft 80 projecting through a hole in plate 30 and is joumaled by a bearing 82 secured to the inner face of the same and a bearing 84 disposed approximately centrally of the

plates

28 and 30 and secured to the center brace 32. A portion of the shaft 80 extends beyond bearing 84 and carries a crank assembly 86 including a wheel 88 and a generally upright drive rod 90 eccentrically connected to the wheel 88 through bearing structure 92. The drive rod 90 is tubular at its marginal ends, the lower end thereof threadably receiving a fastener component 94 connected to bearing structure 92 to provide for longitudinal adjustment of drive rod 90.

The. upright drive rod 90 is pivotally coupled to the main feeder carriage 96 (FIG. 6) for oscillating the latter between raised and lowered positions thereof upon rotation of the main shaft 80. The carriage 96 includes a flat frame member 98 extending practically the distance between

support plates

28 and 30, a pair of spaced-apart end plates 100 bolted to opposite ends of the frame member 98, and three spaced-apart, elongated guide plates 102 of formed sheet material which overlie the frame member 98 and are rigidly fastened thereto between end plates 100. The carriage 96 is supported at one end by a driven shaft 104 (FIG. 8) which extends between the

support plates

28 and 30 joumaled by bearing sets 106, through the table end plates joumaled by suitable bearings I08, and projects through support plate 30 to carry the sprocket 76. A coupling block (FIG. 6) bolted centrally of the frame member 98 carries a short pivot pin 112 which is coupled to an eye 114 adjustably threaded into the upper end of drive rod 90.

Most components of the conveying unit 26 are mounted on the carriage 96 and include a pair of spaced-apart sheaves 116 (FIG. 8) pinned on the shaft 104 for rotation therewith and each carrying an endless belt 118 which couples with other conveying components at the opposite end of the carriage 96 as will hereinafter be described. It may be seen that the sheaves 116 are aligned with the spaces between adjacent guide plates 102, and that the belts 118 are substantially flush with the upper surfaces thereof or extend slightly thereabove for gripping the newspaper sections as they travel along their paths of delivery. A pair of upstanding, U-shaped support brackets 120 mounted on respective end plates 100 pivotally support a pair of rocker arms 122 which extend rearwardl y of carriage 96 and carry a rigid shaft 124 therebetween. The reduced, opposed ends of shaft 124 are rigidly held by suitable setscrews or the like to prevent relative rotation of shaft 124.

A pair of freewheeling rollers 126 are mounted on shaft 124 for rotation thereabout in direct alignment above the belts 118. A spring-loaded hold-down assembly 128 (FIG. 6) is provided on each of the rocker arms 122 to bias the rollers 126 into engagement with the belts 118 forming a nip therebetween for the reception of newspaper sections. Each of the hold-down assemblies 128 includes a threaded element 130 which extends through the corresponding rocker am 122 and is threadably received by the corresponding end plate 100. A coil spring 132 about the element 130 engages the top of the rocker arm 122 and is maintained in a compressed condition by a knob 134 threaded onto element 130.

The carriage end plates 100 carry bushings 136 at the forward ends thereof which serve to journal opposite ends of a tubular shaft 138 (FIG. 5). Three freely rotatable paper-engaging rollers 140 approximately the same diameter as or slightly larger than belts 118 are mounted on the shaft 138 for rotation thereabout and project into cutout portions 102a of the respective guide plates 102. The shaft 138 also supports a pair of spaced-apart bearings 142 which carry sheaves 144 about which the ends of the belts 118 are trained.

The tubular shaft 138 comprises an important part of the gripping assembly 24 as well as of the conveying unit 26 as will hereinafter become clear, and is actuated for oscillation in opposite, timed relationship to the reciprocation of the carriage 96 by a power crank assembly 146 (FIG. 5). The assembly 146 comprises a hollow stub shaft 148 bolted to the support plate 28, an elongated crank arm 150 pivotally coupled to the stub shaft 148 and extending generally upwardly therefrom, and a clamping link 152 eccentrically pinned to the upper end of arm 150 and having a pair of jaws which firmly grip the adjacent end of the shaft 138.

The conveying unit 26 further includes a pair of rocker arms 154 (FIGS. 5 and 6) pinned to the respective support brackets 120 which extend toward the forward or elevated end of carriage 96. Each forward rocker arm 154 rigidly receives a reduced end portion of an elongated shaft 156 spanning the distance therebetween which supports a pair of spaced bearings 158 carrying freely rotatable rollers 160 in alignment above the conveying belts 118. A pair of spaced-apart, curved, upper paper guides 162 are secured between the

shafts

156 and 124 above the guide plates 102 and extend substantially the lengths thereof. The shaft 138 also carries a pair of cams 164 securely clamped thereon by a retaining screw 166 (FIG. 11), each of the cams 164 being disposed between a roller 140 and the adjacent carriage end plate 100. A pair of spaced cam followers 168 are pivotally mounted on adjacent ends of the shaft 156 in alignment above the respective cams 164. The followers 168 are normally biased in a counterclockwise direction viewing FIG. 11 by coil springs 170 about the shaft 156 which are retained thereon by spring retainers 172. A nylon stop 174 behind each of the followers 168 is engageable therewith and is disposed to limit the counterclockwise biasing of the same to the position shown in FIG. 11. A pair of springloaded hold-down assemblies 176 at opposite sides of the carriage 96 on forward rocker arms 154 respectively normally bias the rollers 160 on shaft 156 into engagement with the belts 118 and comprise components identical to those of the rear hold-down assemblies 128.

As mentioned above, the tubular shaft 138 is an essential component of both the conveying unit 26 and the gripping assembly 24, and its role as part of the gripping assembly 24 will now be described in more detail. A plug 178 threaded into the openleft end of the tubular shaft 138 viewing FIG. 5 serves to close the passage 180 therethrough. Four sucker or gripper units 182 are mounted on shaft 138 at spaced intervals therealong and project outwardly therefrom beyond belts 118 as shown generally in FIGS. 3 and 5 and in detail in FIGS. 12 and 13. Referring more particularly to FIGS. 12 and 13, each of the gripper units 182 comprises an elongated plunger 184 extending through the shaft 138 at right angles thereto and having a central, longitudinal bore therein extending from the leading end to approximately the midpoint thereof. Two cross bores through the plunger 184 collectively denoted 188 intersect at the longitudinal bore 186 and communicate the same with the passage 180. A flexible, preferably rubber sucker cap 190 is provided at the outer end of each plunger 184, and an enlargement 192 is removably secured to the opposite end thereof. L-shaped cam fingers 194 are adjustably fastened to the underside of frame member 98 by a pair of mounting screws 196 which extend through enlarged holes in the depending fingers 194. A coil spring 198 about plunger 184 between the enlargement 192 and shaft 138 biases the enlargement 192 and hence plunger 184 rearwardly toward the cam finger 194 shown in engagement with enlargement 192 in FIG. 12, and a shoulder 199 rigid to plunger 184 between the sucker cap 190 and shaft 138 limits the retracting motion of the gripper unit 182 as it engages the surface of shaft 138 illustrated in FIG. 13. It may be seen viewing FIGS. 12 and 13 that gripper unit 182 in FIG. 13 has been rotated approximately 100 to 1 from the position of FIG. 12, and accordingly, in the position of FIG. 13 the gripper unit 182 is free to retract from the extended position of FIG. 12.

The vacuum system which operates to actuate the gripper units 182 includes a vacuum line 200 adapted to be connected to a suitable vacuum pump (not shown), the tubular shaft 138 of gripping assembly 24, and valve apparatus broadly denoted 202 disposed intermediate the shaft 138 and line 200 which is responsive to the reciprocation of the carriage 96 to open and close line 200 in timed relationship to the oscillation of the gripper units 182. The valve apparatus 202 includes a circular member 204 secured to the right carriage end plate 100 and has a central bore 206 which receives the shaft 138 so as to dispose bore 206 in alignment with the passage 180 through shaft 138. Apparatus 202 further includes a circular valve component 208 secured to the outer face of member 204 by a pair of spring-loaded bolts 210 which operate to maintain the component 208 in alignment with member 204, but permit the shiftable insertion of a control plate component 212 therebetween. The control plate 212 is pivotally bolted to the right end plate 100 through a large hole in plate 30 by a bolt 214, and is provided with an elongated clearance slot 216 (FIG. 7) for clearing one of the bolts 210. Plate 212 is also provided with a substantially horizontal, smaller elongated opening 218 which, with the gripper assembly 24 in the position illustrated in FIG. 5, is in alignment with a similar elongated opening 220 which extends inwardly from the back face of component 208 into a cavity 222 (FIG. 5 within the outer face of the component 208. A cover plate 224 fastened to the outer face of component 208 has a fitting 226 therethrough which is adapted to receive one end of the vacuum line 200 whereby to communicate the latter with cavity 222. Additionally, a cross groove 228 is provided in the back face of component 208 above the opening 220 which does not communicate with the cavity 222, but which instead is disposed to communicate with the atmosphere such that the shaft passage 180 may be exhausted when the opening 218 in control plate 212 is disposed in alignment therewith.

In addition to the valve apparatus 202, a control system denoted generally as 230 is provided on the outer face of support plate 30 for regulating the opening and closing of the valve apparatus 202 during operation of feeder 20, and for quickly halting the continued operation thereof upon malfunction of either the gripping assembly 24 or conveying unit 26, such as the failure to pick up and deliver one of the newspaper sections. The control system 230 has an L-shaped mounting block 232 bolted to the outer face of support plate 30 which serves to support most of the components of system 230 including a solenoid 234 secured to block 232 by an L- shaped brace 235, and a specially configured, elongated blocking member 236 which is pivotally secured to the inner face of mounting block 232 between the latter and plate 30. A suitable sensor structure 238 is mounted on the frame member 98 beneath table 96, and is disposed such that the upper margin thereof is presented above the top surface of guide plates 102, hence being engageable with newspaper sections as the latter pass through the feeder 20. A lower stop 240 on the outer face of support plate 30 is disposed in alignment with the control plate 212 for engaging the lower edge of the latter during its reciprocation with the carriage 96, and the retractable, spring-loaded solenoid armature 242 nonnally projects through the mounting block 232 and serves as an upper stop for the control plate 212 as well as a support means beneath the blocking member 236 to prevent the latter from gravitionally swinging beyond its normally raised location.

OPERATION It is to be noted at the outset that all of the figures except FIGS. 2, 7 and 13 show the operating components of feeder 20 in position to begin an operating cycle starting with the gripping of a section from the stack. FIGS. 2, 7 and 13 illustrate the feeder 20 at the midpoint of its operating cycle. Ac-

cordingly, the crank assembly 86 is disposed in its top deadcenter position such that the drive rod 90 maintains the carriage 96 at its upper limit of travel. Also at this time, the crank assembly 146 is disposed to place the gripping assembly shaft 138 in its most counterclockwise position viewing FIG. 12 such that the gripper units 182 are disposed in their initial newspaper gripping positions. Additionally, it may be seen that the top edge of control plate 212 is abutting the armature 242 of the solenoid with the circular member 204 and valve component 208 shifted relative to control plate 212 to dispose their

respective openings

218 and 220 in alignment so as to evacuate passage and gripper plungers 184.

Initially, a stack of newspaper sections or the like which are to be fed through feeder 20 should be placed on table 36 with their folded edges up. Accordingly, the stack will be inclined at approximately 30 from the horizontal viewing FIG. 1, and the lowermost section will be flat against platform 34 with its upper marginal portion overhanging the same. If the marginal portion of the section is not then in alignment with the sucker caps of the gripper units 182, adjustments may be made by rotating the worm gear 52 to cause incremental raising or lowering of the table 36 along platform 34. Further, it is important to insure that the gripper units 182 are extending outwardly far enough to engage the marginal portion. This adjustment may be effected by loosening the mounting screws 196 through the frame member 98 and subsequently shifting the cam fingers 194 into their proper positions.

Since the vacuum line 200 and passage 180 through shaft 138 is evacuated at this time, the sucker caps 190 engage the marginal portion of the newspaper section and firmly retain the same. Clockwise rotation of the main drive shaft 68 viewing FIG. 1 causes further rotation of the shaft 80 to shift the crank assembly 86 from its top dead-center position of FIG. 9.

Rotation of the crank assembly 86 pulls the drive rod 90 downwardly from its upper position and causes the downward travel of the carriage 96. As the carriage 96 begins this movement, the crank assembly 146 causes the vacuum shaft 138 to rotate in a clockwise direction viewing FIGS. 12 and 13 such that the gripper units 182 bend the gripped portion about the axis of shaft 138. Further downward movement of carriage 96 causes continued clockwise rotation of the gripper units 182, and, since the longitudinal axis of shaft 138 is continually lowered at the same rate that the gripper units 182 are being rotated. the gripped portion of the section is bent about such axis without actually pulling on the section itself or moving any part thereof except for that marginal portion which is gripped by the units 182.

It is to be noted that due to the size differences in the sprockets 74 and 76 as well as the relationships of the parts within the feeder 20, the moving parts of the conveying unit 26 are rotated at approximately twice the rotational speed of the moving parts of the gripping assembly 24 at their greatest speed. Accordingly, as the gripper units 182 are carrying the gripped portion of the newspaper section in an arcuate path for later engagement and delivery by the conveying unit 26, the front sheaves 144 carrying the conveyor belts 118 are rotating at a substantially faster speed. Therefore, as the lower face of the newspaper section engages the free wheeling rollers 140, some light contact is made between the belts 118 and the lower face of the section, but due to the high speed of the belts 118 sufficient contact is not made to disturb the bending action of the section.

Referring particularly to FIG. 11, during the clockwise rotation of the shaft 138 the cams 164 have been simultaneously rotated in the same direction to effect the actuation of the forward rocker arms 154. Viewing the right cam 164 shown in FIG. 11, it may be seen that as it rotates in its clockwise direction, the cam follower 168 successively engages a section of the flat stretch 164a and the curved stretch 164b so as to raise the rocker arms 154 and present a space between the rollers 160 and belt 118 to permit reception of the leading marginal edge of the newspaper section.

As the carriage 96 continues to lower and the shaft 138 continues to rotate in its clockwise direction viewing FIG. 12, the enlargements 192 on the ends of gripper units 182 gradually become disengaged from the cam fingers 194. However, the vacuum pressure through the gripper plungers 184 is preferably strong enough to counteract the force of the coil springs 198 to maintain the gripper units 182 in their extended positions as the marginal portion of the end section is engaged by the surface of rollers 140. As the carriage 96 approaches its lower limit of travel, the lowermost edge of control plate 212 nears the lower stop 240. The control plate 212 engages stop 240 when the crank assembly 86 is approximately 10 from its lowermost position, and each of the gripper units 182 is substantially at a 12 o'clock position viewing FIG. 12. Although the control plate 212 is prohibited from further downward movement by the stop 240, the carriage 96 continues to travel downwardly as the crank assembly 86 completes its half revolution, and accordingly, the circular member 204 and valve component 208 of the valve apparatus 202 continue to move with the carriage 96 relative to control plate 212 to begin exhausting the vacuum within passage 180. Downward movement of the carriage 96 continues until the cross groove 228 in valve component 208 is disposed in alignment with the opening 218 in control plate 212 such that the passage 180 is exhausted to the atmosphere with the parts assuming the positions of FIG. 2. At this time, upon loss of vacuum pressure, the gripper units 182 in the 1 oclock position of FIG. 13 are retracted by operation of the coil springs 198 so as to release the gripped marginal portion of the newspaper end section. Immediately thereafter, the cam follower 168 drops off the arcuate stretch 16412 of cam 164 into the cavity 164C to cause the rollers 160 to drop instantly downward and engage the marginal portion between the same and the conveyor belts 118.

As the rollers and conveyor belts 118 engage the marginal portion of the newspaper section, the section is pulled from the stack and moved over the guide plates 102 and sensor structure 238 toward delivery to the inclined shelf 25.

As the carriage 96 is caused to move upwardly from its lowered position shown in FIG. 2 as the crank assembly 86 begins the last half of its revolution, the crank assembly 146 causes the shaft 138 and hence gripper units 182 to rotate in a counterclockwise direction viewing FIG. 13 with the units 182 being disposed in their retracted positions. It may be seen that in this manner, retraction of the units 182 insures that no engagement thereof with the newspaper section being withdrawn from the stack will be effected, so that steady withdrawal will be accomplished. Simultaneously, the cam 164 on each end of shaft 138 begins to rotate in a counterclockwise direction viewing FIG. 11 such that the cam followers 168 tend to climb out of the cavity 164C onto the arcuate stretch 164b thereof. Because of the spring pressure effected by the retainer spring 172 on each of the followers 168, the followers 168 spring outwardly to permit passage of the arcuate stretch 164b and maintain the rocker arms 154 in their lowered positions such that the rollers 160 are continuously down in engagement with the newspaper section. Accordingly, as the shaft 138 is further rotated along with cam 164, the followers 168 continue to travel over the arcuate stretch 16412 and over the flat stretch 164a until such time as the cam 164 is completely rotated to its final position.

As the carriage 96 returns to its upper position, the control plate is carried therewith while the valve member 204 and component 208 remain in the position relative to plate 212 as shown in FIG. 12. As the crank assembly 86 nears 10 from its top dead-center position of FIG. 9, the gripper units 182 have once again been presented in their extended positions by engagement thereof with the cam fingers 194. Also, as the control plate 212 engages the underside ofsolenoid armature 242, the plate 212 is retained while the carriage 96 and the member 204 and component 208 travel upwardly therewith to begin a new cycle of actuating the vacuum system. When the member 204 and component 208 have been completely shifted and the crank assembly 86 is in its top dead-center position, the

openings

218 and 220 are once again in alignment to effect evacuation of the passage so as to once again actuate the gripper units 182.

It may be seen that throughout the one cycle of operation the vacuum gripping assembly 24 was not used to effect withdrawal of the newspaper section, but only to prepare the marginal end portion thereoffor subsequent gripping between the rollers 160 and conveyor belt 118 of the conveying unit 26. Accordingly, the amount of vacuum pressure needed in this instance to effect the bending of the marginal portion of the newspaper section is substantially less than that which would be required if the section were to be completely withdrawn by the gripping assembly 24.

Occasionally, a malfunction of the feeder 20 might occur such as in the instance where the gripping assembly 24 failed to properly engage the newspaper section such that no section would be withdrawn from the stack. In this instance it is desirable to stop the operation of the feeder 20 as well as any additional equipment which might be used to deliver awaiting open newspaper editions at shelf 25. In this respect the provision of the sensor structure 238 operates to actuate the control system 230 to maintain the vacuum line in its exhausted condition for one extra cycle of the gripping assembly 24 as well as to preferably stop the other equipment at the delivery end of the feeder 20. For instance, if the feeder 20 has malfunctioned so that a newspaper section does not pass over the sensor structure 238 to depress the latter, the solenoid 234 may be actuated to withdraw the armature 242 thereof as the carriage 96 is disposed in its lower position. Such withdrawal of the armature 242 permits the blocking member 236 to gravitationally swing into engagement with the valve member 204 when the latter is disposed in its position relative to control plate 212 as shown in FIG. 2. Thus, as the carriage 96 continues to rise with the vacuum passage 180 being exhausted to atmosphere, the protruding leg portion 236a of member 236 (shown best in FIG. 3) serves to block the retracted armature 242 as control plate 212 swings toward its upper disposition. Accordingly, instead of striking the armature 242 and being retained thereby, the control plate 212 shifts past the same until the carriage 96 reaches its upper limit of travel. Thus, no relative shifting of control plate 212 and component 208 has occurred so that the passage 180 is still exhausted to the atmosphere through the cross groove 228.

The control system 230 may be provided with relays or the like which will maintain the solenoid 234 in its actuated condition with the armature 242 being withdrawn until a reactivation switch has been closed, but the present embodiment contemplates having the armature 242 withdrawn for only one cycle of the feeder 20. Accordingly, the blocking member 236 is provided with a second leg 236b which is offset to one side of the leg 236a and crosses over the upper leading edge of control plate 212 therebelow. It may be seen that the leg 236a disposed on the outer side of control plate 212 adjacent the armature 242 is of such a width that when in its uppermost position, the leg 236a permits the passage of the armature 242 beneath the same into engagement with the outer face of the control plate 212 when the solenoid 234 is deactivated. The armature 242 being in engagement with the face of plate 212 has no effect in blocking the same, but as the carriage 96 begins its downward travel, the armature 242 slips off the surface of plate 212 between the space between the latter and member 236 so that the latter is once again held from swinging downwardly. As the carriage 96 continues swinging downwardly and control plate 212 is brought into engagement with the stop 240, the

openings

218 and 220 are once again brought into alignment with one another so as to evacuate the passage 180 and provide for the gripping of a new marginal portion of an end newspaper section from the stack.

It may therefore be seen that the feeding mechanism of the present invention provides a rapid, economical, and reliable means of feeding inserts or the like which has heretofore not been available. The feature of bending the marginal portion of the end newspaper section without moving the remainder of the section at that time eliminates the necessity of having a substantially high-pressure vacuum system. Further, it may be seen that the present feeder may find abundant use in jobs other than stuffing newspapers, such as for rapidly counting sheets and other such operations. In addition, it may be seen that the construction of the air valving system for the feeder and the spacial relationship between the parts thereof and the gripper assembly present a particular advantage in that the valving of the air is disposed relatively close to the suckers, thus requiring a minimum volume of air to be evacuated at the point of pick-up. This is a desired advantage over other types of valving systems which usually have to be located somewhere on the machine where actuation can be obtained mechanically, Such remote location of the valving system manifestly causes a greater volume of air between the valve and the suckers which must be instantaneously evacuated.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. A feeder for flexible sheet material comprising:

a receptacle for receiving and supporting a plurality of said sheets in stacked relationship;

a vacuum operated gripping assembly adjacent said receptacle and provided with a gripper engageable in one position thereof with the marginal portion of an adjacent end sheet of the stack and rotatable through an arcuate path of travel into a sheet releasing position to bend said marginal portion of the end sheet away from the stack without moving the remaining portion of the end sheet;

a conveying unit having a pair of opposed, relatively shiftable delivery elements for receiving a sheet therebetween at said releasing position of the gripper;

power means connected to said gripper for rotating the same through said arc; and

mechanism operably coupled to said gripper assembly and the conveying unit for controlling vacuum pressure to the gripper to cause said one marginal portion of the end sheet to be gripped thereby at said one position of the gripper and to discontinue the vacuum thereto at said release position thereof while actuating the elements in synchronism with said gripper rotation to effect withdrawal of the end sheet from the stack for advancement along a delivery path,

said power means including drive structure operably connected to said gripper assembly for raising and lowering the latter relative to said stack,

said power means being operable to oscillate the gripper between the sheet-engaging and sheet-releasing positions thereof during raising and lowering of the gripper assembly by said structure, there being a vacuum line coupled to said gripper and adapted for connection to a vacuum system, said mechanism including valve apparatus associated with said line and operated in response to raising and lowering of said gripper assembly for opening and closing the line,

said valve apparatus including a pair of opposed, relatively shiftable valve components, one of said components being movable with said assembly during raising and lowering thereof, the other of said components being retainable in a stationary disposition while said one component is shifted relative thereto to effect opening or closing of the line.

2. The feeder as set forth in claim 1, wherein is provided an actuatable control system associated with said valve apparatus for maintaining the vacuum line in a closed condition upon malfunction of thegripping assembly, said system including a solenoid adjacent the upper limit of assembly travel effected by said drive structure and having a retractable plunger normally extended in disposition to engage said other component and retain the same as said one component continues movement with the assembly to open said line, and sensor means connected to said solenoid and operable to sense malfunction of the assembly and actuate the solenoid to withdraw said plunger thereof to clear said other component such that the latter is not retained by the plunger and no relative shifting of the components occurs to open said line.

3. The feeder as set forth in claim 2, wherein said control system further includes a blocking member mounted for shifting movement relative to said solenoid plunger and normally resting thereon, said member being disposed for movement into blocking relation with said plunger and engagement with said valve apparatus upon actuation of the solenoid to maintain the plunger in a withdrawn disposition such that said other component is not retained by the plunger.

4. A feeder for flexible sheet material comprising:

a carriage rotatably mounted adjacent the receptacle for movement along a reciprocal path to cause one end of the carriage to move past a marginal portion of one end sheet of the stack thereof;

a tubular shaft rotatably carried by the carriage for pivoting about an axis parallel with and spaced from the axis of rotation of the carriage;

a series of spaced, vacuum operated hollow grippers carried by the shaft in generally perpendicular relationship thereto and communicating with the passage through the shaft;

operating mechanism coupled to the carriage and to the shaft for reciprocating the carriage and oscillating the shaft in timed relationship;

cam means on the grippers and said carriage cooperable to shift the grippers into extended first positions engageable with the marginal portion of said end sheet of the stack when the carriage is at one end of its path of travel away from the marginal edge of the end sheet and the shaft is in disposition with the grippers extending therefrom toward the stack, and to retract the grippers into sheet releasing positions in response to movement of the carriage toward the marginal portion of the end sheet and rotation of the shaft through an arc to bend said marginal portion of the gripping position thereof and for discontinuing said pressure when the gripper is in the sheet-releasing position thereof,

said vacuum line defining said axis of rotation of the .P said me being supported for rotation about said axis and having the gripper mounted thereon for rotation sheet gripped by the grippers away from the stack without 5 therewfthi l moving the remaining portions ofthe end Sheet; a conyeymg unit associated with said grlppmg assembly and movable conveying means carried by the carriage and posh oscillatable therewith for completing removal of the end tioned to receive an end sheet removed from the stack sheet the and to transfer the removed sheet to a point remote from said a .rotary emem mounted f i the receptacle; 1O vacuumlme for rotat on relative thereto about said axis shiftable elements normally proximal to the conveying mtanon h gnpper having an outer. surface means for cooperating therewith to shift a removed sheet qlsposed for fnctlonany e.ngagmg Sald one {marginal por- I tion of the end sheet as it is bent about said axis of the to said remote point, d cam means engageable with the shiftable elements and cargripper r means for driving said element in a direction to pull the end ried by said shaft for moving the shiftable elements away from the conve in means throu h a dis 1 cement to Sheet .from h stack when the gripper reaches Sheet y g g p releasing position. i the i Sheet thereigetween held by Said i i 7. The feeder as set forth in claim 6, wherein said gripper is f romnmi thereof 0 t shaft as the carnage ls shiftable between an outer extended sheet-engaging location Shmeq from sald one end of its travel toward the and an inner retracted sheet-releasing location in synchronism opposite endflereof for retummg the .Shlftable with the opening and closing of said line by said control mems to Posmons proxlmfal to the fe means as mechanism, there being actuating means engageable with said t gnppers approach release Posmonsi a Vacuum gripper for effecting extension thereof as the assembly is line; swung away from said opposite marginal portion and the vacuum control valve apparatusconnectmg saldhne to the gripper rotated into said Sheehengaging position and rehab Shaft mounted on carnage and mcludmg tion thereof as the assembly is swung toward said opposite ctfmponems presentmg a Compartment commumcatfng marginal portion and the gripper rotated into said sheetwiththe atmosphere and a passage leading from the line releasing position t 531d Shaft 8. In a feeder for flexible sheet material: Said apparatus t being Ptovlded with a eohtro! Plate a receptacle for receiving and supporting a plurality of the movably carried by the components and operable in first Sheets in Stacked relationship; and second locations thereof to commun cate the shaft a gripping assembly adjacent Said receptacle and provided with said and the Compartment respectively; and with a gripper engageable in one position thereof with p means located to he engaged y the Plate dth'mg one marginal portion of the end sheet of the stack and reciprocation of the e to Shift the Plate from the 3 5 rotatable into a sheet-releasing position about an axis first location thereof to the second location as the carspaced f the end Sheet i the direction f f di riage moves from said one position of the same to its h f; other Position and Vetsapower means operably coupled with the gripper for rotating 5. A feeder as set forth in claim 4, wherein the stop located the same about said axis between said positions and for IO effect shifting of the plate IO said first location thereof is 40 simultaneously shifting the assembly and hence said axis movable to a disposition clearing the plate, and seiectively acgenerally toward the opposite marginal portion of the end tuatable means coupled to said movable stop for shifting the heet for a sufficient distance to cause the gripped marlatter. ginal portion to bend about said axis away from the stack 6 In a feeder for flexible sheet material: without moving the remainder of the end sheet, thereby a receptacle for receiving and supporting a plurality of the initiating removal of the end sheet from the stack;

sheets in stacked relationship; a conveying unit associated with said gripping assembly and a gripping assembly adjacent said receptacle and provided oscillatable therewith for completing removal of the end with a gripper engageable in one position thereof with sheet from the stack, one marginal portion of the end sheet of the stack and said unit including a rotary element mounted on said rotatable into a sheet-releasing position about an axis vacuum line for rotation relative thereto about said axis spaced from the end sheet in the direction of feeding of rotation of the gripper and having an outer surface thereof; disposed for frictionally engaging said one marginal porpower means operably coupled with the gripper for rotating tion of the end sheet as it is bent about said axis of the the same about said axis between said positions and for gripper; and simultaneously shifting the assembly and hence said axis means for driving said element in a direction to pull the end generally toward the opposite marginal portion of the end sheet from the stack when the gripper reaches its sheetsheet for a sufficient distance to cause the gripped marreleasing position. ginal portion to bend about said axis away from the stack h feeder as set forth in Claim wherein Said assembly without moving the remainder f the d Sheet, h b and said unit are supported for oscillation together about a initiating removal of the end sheet from the stack, Second axis Spaced from the axis of totatioh of the gripper ht said assembly being supported for oscillation about a i direction of feeding of the end Sheet Sat-d P Y means second axis spaced from the axis of rotation of the gripper belhg p r e to oscillate the g p about its 3x15 in ttmed in Said direction f f di f the end Sheet, relationship w th oscillation of the assembly and the unit about said power means being operable to oscillate the gripper 531d second axlsabout its axis in timed relationship with oscillation of said The feeder as Set forth elalm whereth Said PPe assembly about Said Second axis, vacuum-operated and wherein 15 provided control mechanism said gripper being coupled with a vacuum supply line for operably p e wtth 531d PP hp h Vacuuth P e vacuum-operation, there being control mechanism e f the PP whet} the e e ls h the pp g operably Coupled with Said gripper for providing vacuum positionthereof and for discontinuing said pressurewhen the pressure for the gripper when the latter is in the Sheet gripper IS in the sheet-releasing position thereof, said control mechanism being operable in response to said oscillation of the assembly and the unit about said second axis.

a at t a m

Claims

1. A feeder for flexible sheet material comprising: a receptacle for receiving and supporting a plurality of said sheets in stacked relationship; a vacuum operated gripping assembly adjacent said receptacle and provided with a gripper engageable in one position thereof with the marginal portion of an adjacent end sheet of the stack and rotatable through an arcuate path of travel into a sheet releasing position to bend said marginal portion of the end sheet away from the stack without moving the remaining portion of the end sheet; a conveying unit having a pair of opposed, relatively shiftable delivery elements for receiving a sheet therebetWeen at said releasing position of the gripper; power means connected to said gripper for rotating the same through said arc; and mechanism operably coupled to said gripper assembly and the conveying unit for controlling vacuum pressure to the gripper to cause said one marginal portion of the end sheet to be gripped thereby at said one position of the gripper and to discontinue the vacuum thereto at said release position thereof while actuating the elements in synchronism with said gripper rotation to effect withdrawal of the end sheet from the stack for advancement along a delivery path, said power means including drive structure operably connected to said gripper assembly for raising and lowering the latter relative to said stack, said power means being operable to oscillate the gripper between the sheet-engaging and sheet-releasing positions thereof during raising and lowering of the gripper assembly by said structure, there being a vacuum line coupled to said gripper and adapted for connection to a vacuum system, said mechanism including valve apparatus associated with said line and operated in response to raising and lowering of said gripper assembly for opening and closing the line, said valve apparatus including a pair of opposed, relatively shiftable valve components, one of said components being movable with said assembly during raising and lowering thereof, the other of said components being retainable in a stationary disposition while said one component is shifted relative thereto to effect opening or closing of the line.

2. The feeder as set forth in claim 1, wherein is provided an actuatable control system associated with said valve apparatus for maintaining the vacuum line in a closed condition upon malfunction of the gripping assembly, said system including a solenoid adjacent the upper limit of assembly travel effected by said drive structure and having a retractable plunger normally extended in disposition to engage said other component and retain the same as said one component continues movement with the assembly to open said line, and sensor means connected to said solenoid and operable to sense malfunction of the assembly and actuate the solenoid to withdraw said plunger thereof to clear said other component such that the latter is not retained by the plunger and no relative shifting of the components occurs to open said line.

4. A feeder for flexible sheet material comprising: a receptacle for receiving and supporting a plurality of said sheets in stacked relationship; a carriage rotatably mounted adjacent the receptacle for movement along a reciprocal path to cause one end of the carriage to move past a marginal portion of one end sheet of the stack thereof; a tubular shaft rotatably carried by the carriage for pivoting about an axis parallel with and spaced from the axis of rotation of the carriage; a series of spaced, vacuum operated hollow grippers carried by the shaft in generally perpendicular relationship thereto and communicating with the passage through the shaft; operating mechanism coupled to the carriage and to the shaft for reciprocating the carriage and oscillating the shaft in timed relationship; cam means on the grippers and said carriage cooperable to shift the grippers into extended first positions engageable with the marginal portion of said end sheet of the stack when the carriage is at one end of its path of travel away from the marginal edge of the end sheet and the shaft is in disposition with the grippers extendIng therefrom toward the stack, and to retract the grippers into sheet releasing positions in response to movement of the carriage toward the marginal portion of the end sheet and rotation of the shaft through an arc to bend said marginal portion of the sheet gripped by the grippers away from the stack without moving the remaining portions of the end sheet; movable conveying means carried by the carriage and positioned to receive an end sheet removed from the stack and to transfer the removed sheet to a point remote from the receptacle; shiftable elements normally proximal to the conveying means for cooperating therewith to shift a removed sheet to said remote point; cam means engageable with the shiftable elements and carried by said shaft for moving the shiftable elements away from the conveying means through a displacement to admit the end sheet therebetween held by said grippers during rotation thereof of the shaft as the carriage is shifted from said one end of its path of travel toward the opposite end thereof and for returning the shiftable elements to positions proximal to the conveying means as the grippers approach their release positions; a vacuum line; vacuum control valve apparatus connecting said line to the shaft, mounted on said carriage and including hollow components presenting a compartment communicating with the atmosphere and a passage leading from the line to said shaft, said apparatus further being provided with a control plate movably carried by the components and operable in first and second locations thereof to communicate the shaft with said line and the compartment respectively; and stop means located to be engaged by the plate during reciprocation of the carriage to shift the plate from the first location thereof to the second location as the carriage moves from said one position of the same to its other position and vice versa.

5. A feeder as set forth in claim 4, wherein the stop located to effect shifting of the plate to said first location thereof is movable to a disposition clearing the plate, and selectively actuatable means coupled to said movable stop for shifting the latter.

6. In a feeder for flexible sheet material: a receptacle for receiving and supporting a plurality of the sheets in stacked relationship; a gripping assembly adjacent said receptacle and provided with a gripper engageable in one position thereof with one marginal portion of the end sheet of the stack and rotatable into a sheet-releasing position about an axis spaced from the end sheet in the direction of feeding thereof; power means operably coupled with the gripper for rotating the same about said axis between said positions and for simultaneously shifting the assembly and hence said axis generally toward the opposite marginal portion of the end sheet for a sufficient distance to cause the gripped marginal portion to bend about said axis away from the stack without moving the remainder of the end sheet, thereby initiating removal of the end sheet from the stack, said assembly being supported for oscillation about a second axis spaced from the axis of rotation of the gripper in said direction of feeding of the end sheet, said power means being operable to oscillate the gripper about its axis in timed relationship with oscillation of said assembly about said second axis, said gripper being coupled with a vacuum supply line for vacuum-operation, there being control mechanism operably coupled with said gripper for providing vacuum pressure for the gripper when the latter is in the sheet-gripping position thereof and for discontinuing said pressure when the gripper is in the sheet-releasing position thereof, said vacuum line defining said axis of rotation of the gripper, said line being supported for rotation about said axis and having the gripper mounted thereon for rotation therewith; a conveying unit associated with said gripping assembly and oscillatable therewith for completing removal of the end sheet from the stack, said unit including a rotary element mounted on said vacuum line for rotation relative thereto about said axis of rotation of the gripper and having an outer surface disposed for frictionally engaging said one marginal portion of the end sheet as it is bent about said axis of the gripper; and means for driving said element in a direction to pull the end sheet from the stack when the gripper reaches its sheet-releasing position.

7. The feeder as set forth in claim 6, wherein said gripper is shiftable between an outer extended sheet-engaging location and an inner retracted sheet-releasing location in synchronism with the opening and closing of said line by said control mechanism, there being actuating means engageable with said gripper for effecting extension thereof as the assembly is swung away from said opposite marginal portion and the gripper rotated into said sheet-engaging position, and retraction thereof as the assembly is swung toward said opposite marginal portion and the gripper rotated into said sheet-releasing position.

8. In a feeder for flexible sheet material: a receptacle for receiving and supporting a plurality of the sheets in stacked relationship; a gripping assembly adjacent said receptacle and provided with a gripper engageable in one position thereof with one marginal portion of the end sheet of the stack and rotatable into a sheet-releasing position about an axis spaced from the end sheet in the direction of feeding thereof; power means operably coupled with the gripper for rotating the same about said axis between said positions and for simultaneously shifting the assembly and hence said axis generally toward the opposite marginal portion of the end sheet for a sufficient distance to cause the gripped marginal portion to bend about said axis away from the stack without moving the remainder of the end sheet, thereby initiating removal of the end sheet from the stack; a conveying unit associated with said gripping assembly and oscillatable therewith for completing removal of the end sheet from the stack, said unit including a rotary element mounted on said vacuum line for rotation relative thereto about said axis of rotation of the gripper and having an outer surface disposed for frictionally engaging said one marginal portion of the end sheet as it is bent about said axis of the gripper; and means for driving said element in a direction to pull the end sheet from the stack when the gripper reaches its sheet-releasing position.

9. The feeder as set forth in claim 8, wherein said assembly and said unit are supported for oscillation together about a second axis spaced from the axis of rotation of the gripper in said direction of feeding of the end sheet, said power means being operable to oscillate the gripper about its axis in timed relationship with oscillation of the assembly and the unit about said second axis.

10. The feeder as set forth in claim 9, wherein said gripper is vacuum-operated and wherein is provided control mechanism operably coupled with said gripper for providing vacuum pressure for the gripper when the latter is in the sheet-gripping position thereof and for discontinuing said pressure when the gripper is in the sheet-releasing position thereof, said control mechanism being operable in response to said oscillation of the assembly and the unit about said second axis.