US2974950A - Sheet feeding mechanism - Google Patents

Description

M r h 14, 1 B. B. PASQUINELLI ETAL' 2,974,950

' SHEET FEEDING MECHANISM Filed July 1, 1959 5 Sheets-Sheet 1 INVENTORS BRUNO B- PASQUINELLI BY HENRI E. PEYREBRUNE a u-vi/mexzaluvw ATTORNEYS March 1961 B. B. PASQUINELLI ETAL 2,974,950

SHEET FEEDING MECHANISM 3 Sheets-Sheet 2 Filed July 1, 1959 March 14, 1 1 B. B. PASQUINELLI ETAL 2,974,950

SHEET FEEDING MECHANISM 3 Sheets-Sheet 3 Filed July 1. 1959 INVENTORS BRUNO B. PASQUINELLI BY HENRI E. PEYREBRUNE Ullltfi 1 snnnr nnnnnwo MECHANISM Bruno B. Pasquinelii, Evergreen Park, and Henri E.

Peyrebrune, River Forest, 111., assignors to Miehle- Goss-Dexter, Incorporated, Chicago, Ill., a corporation of Delaware Filed July 1, 1959, Ser. No. 824,402 12 Claims. (Cl. 271-44) tered in feeding the carton stock to the respective processing machines with any degree of regularity. This is due primarily to the inherent tendency of most carton material, and particularly corrugated board, to curl or warp after it is cut into sheets and, consequently, when such stock is placed in the processing machine hopper or magazine the sheet engaging elements of the conventional feeding mechanisms cannot properly engage and separate the individual sheets. This condition obviously causes frequent trip-ups and, as a result, the output of the processing machine is reduced far below its normal capacity.

In order to feed such warped sheets it has been the practice in some instances to place weights on top of the feeder pile in order to flatten the sheets and maintain the edges thereof in proper feeding position. This practice is unsatisfactory, however, because the added weight increases the coeflicient of friction between the sheets, requiring that much greater force be exerted against the rear edge of each succeeding bottom sheet in order to advance them from beneath the pile and such excessive resistance invariably causes these edges to become damaged. Moreover, if the sheets have already been printed, the increased friction often causes the printed images to be smudged or scratched.

It has also been proposed to make the sheet engaging elements adjustable vertically relative to their supporting carriage so they can be raised above their normal plane of travel to engage the rear edges of Warped sheets. This arrangement also is impractical because the extent of adjustment not only is too limited, but each time the raised elements reciprocate beneath the pile, they jostle and generally disturb all of the remaining sheets in the stack. Moreover, it still is necessary to apply weights to the front edge of the stack so that the leading edge of the bottom sheet will be held down in position to pass through the usual gate or sheet calipering means.

It is a primary object of this invention, therefore, to provide an improved bottom sheet feeder wherein means are provided for adjusting the path of the slider carriage with direct relation to the radius of curvature of the sheets to thereby assure constant operation at high speeds regardless of the Warped condition of the stock to be fed.

A further object is to provide a bottom sheet feeder wherein the guide means for the reciprocating slider carriage is adjustable whereby to maintain the path of the sheet engaging elements substantially normal to the radius of curvature of the sheets at the rear edge thereof regard- States Patent ice H less of the warped condition or direction of curvature of the sheets.

Another object resides in the provision of means where? by the rear edge stack supporting means is adjustable with the'slider carriage guide means so that the front edge of the bottom sheet is moved into proper feeding position as; 7 said guide means are adjusted to move the path of the" sheet engaging elements normal to the radius of curvature of the sheets at the rear edge thereof.

A still further object is to provide a bottom sheet feeder mechanism having detector means for sensing the warped condition of the sheets to be fed and which'in, corporates mechanism, which is responsive to the detec-T tor means for automatically adjusting the feeder mechanism with direct relation to the warped condition of the sheets.

Another object is to provide an automatically adjust able bottom sheet feed mechanism wherein means are provided for manually and/ or automatically tripping the sheets out of the path of the sheet engaging elements if the next succeeding sheet tobe fed is improperly posiw tioned.

Qther objects and advantages will become apparent from the following description and accompanying draw.- ings which disclose a preferred embodimentof the inve'n: tion and wherein: 1'

Figure 1 is a side elevational view of the feeder mecha nism with parts thereof shown in section to illustrate structural features;

Figure 2 is an end view, partly in section, and showing substantially one half of the assembly as seen from the right in Figure 1; Figure 3 is a sectional view showing how the sheet engaging elements are adjustably secured to the slider carriage;

Figures 6 and 7 are enlarged views illustrating details of the sheet tripping mechanism.

Referring now to the drawings and with particular reference to Figure 1, the invention is disclosed as embodied in a bottom sheet feeding mechanism wherein a slider carriage 10 is mounted for reciprocation in a path below and parallel with a stack of sheets 11, said car-: riage being provided with sheet engaging elements 12 which are adapted to engage the rear edge of and advance each succeeding bottom sheet from beneath said stack toward a suitable sheet receiving machine. i a.

Each time the carriage moves on the feed stroke of its reciprocating cycle, to the left in Figure 1, the elements 12 engage the bottom-most sheet and project it through a gate or choke opening 13 into the nip of' the draw rollers 14 and 15. These rollers in turn are ro-g tated at a constant speed by suitable drive mechanism,'not shown, and serve to advance the sheet over the bridge 16 andonto the continuously moving tapes 17. 'At this point the riderrollers 18 coact with the tapes to move the individual sheets into a register position at thefor ward end thereof from whence they may be fed into a sheet processing machine such as, for example, a die cutting and creasing machine all as is well known in the art.

As illustrated in Figure 1, the sheets 11 of cardboard or corrugated board to be processed are placed in a hopper Patented Mar. 14, 1961 a At the front end of the hopper the sheets are maintained in aligned position by one or more vertically disposed flat bars 22 which constitute the front wall of the hopper. These bars are positioned above the front ramp 19 and have coaction with the top surface of said ramp to form the gate or choke opening 13 through which each succeeding bottom sheet must pass as it is advanced by the pusher elements 12. The bar 22 is supported in a bracket 23 mounted on the transverse shaft 24 and it is adapted to be adjustable vertically in said bracket, relative to the ramp 19, so that the size or height of the choke opening 13 can be varied with direct relation to the thickness of the sheets to be fed. This opening is preferably made slightly greater than the thickness of a single sheet so that during operation of the feeder only the bottom sheet can be advanced during each forward stroke of the carriage. To provide the required adjustability the bar 22 may be formed with beveled edges which are slidable vertically in a corresponding dovetail groove in the bracket 23 and it may be locked in any adjusted position by means such as the thumb screw 26.

The apparatus thus far described is more or less conventional and similar elements may be found in many of the known feeders of this type. The novelty of the invention, however, resides in the mechanism, presently to be described, whereby the slider carriage and the backstop assembly 21 are mounted for angular adjustment relative to the normal horizontal plane as shown in Figure 1, to thereby compensate for any warpage or curvature in the sheets. This feature represents an important advantage over the known feeding devices because it provides simple and efiicient means for effecting angular adjustments of the slider carriage guide means with direct relation to the radius of curvature of the sheets whereby the path of movement of the sheet engaging elements 12 may be maintained substantially normal to the radius of curvature of the sheets at the rear edge thereof to thereby assure positive engagement of said elements with each succeeding bottom sheet.

As shown in Figures 1 and 2, the guide means or track assembly on which the slider carriage 10 is mounted for reciprocation below the stack of sheets 11 is comprised of a series of horizontally disposed tracks 27 which are arranged in parallel spaced relation across the full width of the feeder. In the embodiment illustrated, seven such tracks are provided, four of said tracks being shown in Figure 2 and these may be formed from hollow tubular stock of substantially square cross section, and one end of each track is secured, as by welding, to a transverse supporting shaft 28 to form an integral unit. The opposite or forward end of each track member is provided with a hinge member 29 each of which is pivotally mounted on a transverse shaft 31 so that the complete track assembly can be pivoted about the axis of said shaft for the purpose to be more fully explained hereinafter. The shaft 31 is preferably located adjacent the front ramp 19, so that the pivot axis of the track assembly will be located closely adjacent to the gate 13.

The rear end of the track assembly is supported in its operative position by means of a jack screw 32, which is adjustable whereby to vary the angular position of the track assembly. about the axis of the shaft 31. One end of the jack screw is pivotally mounted on the short shaft 33 journalled in the pillow blocks 34 attached to the bottom side of the supporting shaft 28, and the depending end of said screw is threaded through a jack nut 36 mounted for rotation about a substantially vertical axis in the trunnion 37. The latter member, in turn, is pivotally mounted in the flanges 38 formed on the two center frame brackets 39.

The jack nut 36 is adapted to be rotated in the trunnion 37 whereby to vary the effective length of the screw 32 and is provided with gear teeth 41 at one end thereof which have meshing relation with a worm 42. The latter member is secured to a shaft 43 which is rotatable in the face plates 44 of the trunnion 37 and one end of said shaft extends beyond the rear face plate to receive a hand lever 46. Since the jack nut is restrained against axial movement in the trunnion 37 by means of the shoulder 47 formed on the gear 41 and by the lock ring 48 at the depending end of the jack nut, it will be evident that when the nut is turned by rotating the lever 46, the etfective length of the screw 32 will be varied to thereby pivot the slider carriage track assembly about the shaft 31. When such adjustments are made the trunnion 37 also will pivot about its axis to thereby compensate for any change in the angular position of the screw 32.

The slider carriage 10, which is mounted for reciprocation on the track assembly regardless of its angular position of adjustment, is comprised of a series of hollow tubes 51, see Figure 2, which are slightly larger in cross section than the track members 27 so that they fit over said members in telescoping fashion and they may be grooved along the bottom face thereof as at 52 to facilitate removal of the carriage from the track assembly without disassembling the supporting track assembly. This construction has the advantage in that it permits free movement of the carriage longitudinally on said members, but precludes any lateral or vertical movement thereof relative to the track members, regardless of the angular position of the track assembly or the speed at which the device is operated.

Mounted transversely across the carriage tubes 51 adjacent the rear ends thereof is a fiat bar 53 which ties the respective tubes together as a unit and provides support for the sheet engaging elements or pusher blades 12 as they are more commonly known. This bar extends substantially across the full width of the feeder and is releasably fastened to the respective tubes 51 by means of L-shaped clamps 54 see Figure 3 which are attached to the bar by screws 56 and are adapted to fit over the flanges 57 provided along the top edge of each of the carriage tubes. Thus the bar 53 may be adjusted lengthwise of the carriage tubes in accordance with the size of the sheets to be fed and is locked in position by tightening the screws 56 and clamps 54.

The pusher blades 12, a series of which are arranged in spaced relation along the bar 53, may be formed of flat spring metal and each is provided with sheet engaging hooks or teeth 58, Figure 1, at the free end thereof. These blades preferably are secured to the beveled face 59 of the supporting bar 53 and the teeth 58 are adapted to engage the rear edge of each succeeding bottom sheet and project them through the gate 13, as the carriage reciprocates. In order to assure engagement with the edges of the sheets, the beveled face of the bar 53 is formed at an angle such that a slight tension is induced in the blades which urges them upwardly against the lower face of the bottom sheet during the return stroke of the carriage and so that they will spring upwardly to a limited extent as the carriage reaches the end of its return stroke to engage the rear edge of the next succeeding bottom sheet.

At the front end of the slider carriage the respective tubes 51 are connected to a cross shaft 61 by means of an extension 62 formed integral with each tube and which projects forwardly below the respective track members 27. The cross shaft 61 functions to align the respective tubes for reciprocation as an integral unit on the supporting tracks 27 and is connected by means of a link 63 at each end thereof, to the drive mechanism whereby the carriage is reciprocated. As shown best in Figure l, the links 63 are connected to the free ends of arms 64 on the transverse shaft 66 which is adapted to be oscillated whereby to transmit reciprocating motion to the slidcr carriage 10.

The shaft 66 is rotatably mounted in the frame brackets 39 and is provided with a lever 67 at one end thereof which is connected by a link 68 to a lever 69 mounted on the stub shaft 71. Lever 69 is in turn connected by a link 72 to a corresponding lever 73 which is secured to the end of a drive shaft 74 rotatably mounted in the fram member 76.

The drive shaft 74 may be driven by any suitable means so as to reciprocate the slider carriage at the required speed and in timed relation with the associated processing machine and, as shown, the drive means may be in the form of a worm gear 77 which is fixed to the shaft 74 and meshes with a worm 78 on a shaft 79. The latter shaft may be driven from any suitable source of power such as the main drive mechanism of the processing machine.

With regard to the drive mechanism it will be noted that the drive shaft 74 is offset with respect to the driven shaft 71 and thus the driving force is transmitted through the lever 73 and link 72 tothe lever 69 and link 68. Thus as the respective levers rotate this drag link connection impmts variable speed reciprocating motion to the slider carriage and this motion preferably is such that the pusher blades 12 will engage the rear edge of each bottom sheet while they are moving at a slow speed so as to preclude damaging said edge, whereupon they are quickly accelerated as the carriage continues its feed stroke so that the sheet is travelling at the same surface speed as the continuously rotating draw rollers 14 and 15 as it moves into the nip thereof. Moreover, as the carriage completes its forward stroke, it is reversed and returned at high speed so that maximum time is available in the cycle for the variable speed feeding stroke. Thusrthe slider carriage will be reciprocated at variable speeds whereby to advance each succeeding bottom sheet from beneath the stack in regular order and the pivotal connection between the drive mechanism and the carriage, ile. the link 63, will permit the carriage to move in any angular position of adjustment of the track assembly as required by the curvature of the sheets without in any way affecting the drive mechanism. 7

In order to maintain the leading edge of the bottom sheet of a stack of warped sheets in feeding position with relation to the gate 13, the backstop assembly 21, which supports the rear edge of the stack, also is mounted on the slider carriage track assembly for movement therewith when the latter is adjusted about the axis of the shaft 31. As shown best in Figure 2, the backstop assembly is comprised of a series of brackets 81 and 82 which are secured in spaced relation on a transverse shaft 83, and the end and center brackets 81 thereof are adapted to support the complete assembly on the corresponding end and center tubes of the track assembly. These brackets extend below the intermediate brackets 82 and are providedv with grooves 84 in their bottom edges which are adapted to fit over the respective track members and they preferably have a sliding fit so that the backstop assembly can be adjusted longitudinally on the track members to thereby position the assembly with relation to the size of the sheets to be fed. In this respect it will be noted that the brackets 81 are supported on the end and center track members whereas the slider carriage is mounted for reciprocation on the intermediate track members so that longitudinal adjustments of the backstop assembly will not interfere with the movements of the carriage.

Each end bracket 81 also is provided with means in the form of a transversely disposed shaft 85 having an eccentric portion 86 at the center thereof, for releasably securing the backstop assembly in adjusted position longitudinally on the track members. The shaft 85 is rotatable in the bracket 81 and when turned in clockwise direction, as viewed in Figure l, by means of the lever 87, the

eccentric portion 86 thereof projects into the groove 84 in the bracket to engage the surface of the track member. This in turn brings the edges of the bracket in tight frictional engagement with the track member, to thereby lock it in position and prevent unintended movement of the assembly while the feeder is in operation.

The fingers-20 which support the rear edge of the stack of sheets are mounted in the backstop assembly on a supporting shaft 88 which is arranged below and parallel, to the shaft 83 and is rotatable in the brackets 81 and 82. At each end, the shaft 88 is provided with a lever 89 by means of which the shaft 88 and therewith the fingers 20 can be rocked to trip the sheets out of the path ofthe pusher blades 12.

As shown in Figure 1, the lever 89 is clamped tothe shaft 88 and its free end is bifurcated to fit about a control through the lever 89 and the fingers 20 will raise the rear edge of the bottom sheet above the path of the recipro eating pusher blades 12 and because the backstop assem{- bly is mounted to move up .and down with the track assembly, the fingers 20 will be effective to trip the feeding action regardless of .the angular position of the'track assembly. j

Having thus described the various elements of this invention a brief description of its operation is as follows. It will be appreciated, of course, that when the sheets to be fed are in fiat condition, the feeder assembly will be set substantially as illustrated in Figure l and the flexible spring urged pusher blades 12 will effectively engage and advance each succeeding bottom sheet through the gate 13 without difiiculty'as the carriage 10 reciprocates on the track assembly. 7

However, when the sheets are warped or curved as illustrated schematically in Figure 4 the upward motion of the pusher elements is too limited to compensate therefor and the hooks or teeth 58 will not engage the rear edge of the bottom sheet. In the illustration in Figure 4, it also will be noted that not only is the -rear edge of the bottom sheet raised above the normal path of the pusher blades, but also that the front edge of said sheet is out of line with the gate 13. p

This condition can be readily compensated for in ac} cordance with the present invention by turning the handwheel 46 to thereby increase the effective length of the jack screw 32 until the rear end of the track assembly is raised to the positionsubstantially as illustrated in Figure 4a. By raising the track assembly and therewith the backstop assembly about the pivot axis 31, the'rear end of the stack 11 is raised until the leading edge of the bottom sheet is lined up with the gate 13 to assure free movement of the sheet through said passage. At the same time, the path of the slider carriage is adjusted so as to be substantially normal to the radius of curvature of the sheets at the rear edge thereof. Thus the pusher blades 12 will be effective to engage each succeeding bottom sheet and the direction of the force exerted against the rear edge of the sheet by the pusher blades will always be substantially normal to the radius of curvature thereof.

In Figure 5 the sheets are illustrated as being curved in the opposite manner with respect to those in Figure 4. In such case the leading edge of the bottom sheet would normally be in position to pass through the gate 13 and the pusher blades would effectively engage the rear edge of each succeeding bottom sheet. However, due to the through the edge of the sheet causing a misfeed and the press must be stopped to clear it. Moreover, if the sheet has already been printed, the sculnng effect of the gate member as the sheet is forced through the gate 13 invariably damages the impression beyond use..

' In accordance with this invention, however, the track assembly would be lowered as illustrated in Figure a by a reverse adjustment of the hand lever 46 to thereby decrease the effective length of the jack screw 32 until the path of the slider carriage is substantially normal to the radius of curvature of the sheets at the rear edge. Consequently the force exerted against the rear edge of the sheets by the pusher blades will again be substantially normal to the radius of curvature of the sheets and each bottom sheet will clear through the gate 13 without excessive resistance or binding against the lower edge of the bar 22.

Although the invention thus far has been described as being manually controlled in order to adjust the position of the track assembly and the sheets, the entire operation can be performed automatically. As shown in Figure 1 the condition of the sheets can be sensed by detector means such as, for example, the micro switches 94 and 95. These detectors would be effective to sense not only the presence of sheets to be fed, but also the warped condition of the sheets and the direction of curvature thereof and would actuate suitable servo-mechanisms .toaccomplish the required adjustment of the feeder mechanism.

The detector 94 preferably is set to very close limits so that the leading edge of the bottom sheet must be in position to clear through the gate 13 in order for the feeder to operate. The detector 95 on the other hand would have substantially greater limits and would serve to control the angular adjustment of the track assembly with relation to the direction of curvature of the sheets. The two detectors would be connected in appropriate circuits and in such a manner that both of the switches associated therewith must be open before the feeder would operate.

Detector 95 would be adjustable longitudinally on the track assembly so as to be effective for various size sheets and it would be mounted in such manner that it would move upwardly with the track assembly when the latter is raised, but it would not move lower than the horizontal position as illustrated in Figure 1.

With reference to Figure 4, it will be noted that the curvature of the sheets is such that detector 95 would be depressed when the track assembly is in the horizontal position and thus its switch and associated circuit would be open. The switch associated with detector 94, however, would be closed because the front edge of the stack of sheets is raised above the ramp 19 and the bottom sheet is not in position to clear through the gate 13. Accordingly the circuit associated with detector 94 would be closed and would actuate a suitable servo-mechanism, such as a reversible electric motor 104 connected to the worm shaft 43, to thereby raise the rear end of the track assembly until the sheets and the track assembly reach the proper position. The detector 95 would rise with the track assembly under these circumstances and the upward movement would continue until detector 94 is depressed when the leading edge of the bottom sheet moves to the proper feeding position. This in turn would break the circuit at a time when the assembly is substantially in the position as illustrated in Figure 4a.

Under conditions as illustrated in Figure 5, detector 94- obviously would be depressed whereas detector 95 would not. Thus the circuit associated with the latter would be closed causing the servo-mechanism to be actuated in reverse direction to thereby lower the track assembly. As stated above, the detector 95 does not move downwardly with the track assembly beyond the horizontal position and thus the downward movement of the track assembly would continue until the body of the sheets contacted and depressed the detector thereby opening the circuit when the assembly has reached the position indicated in Figure 5a.

The particular servo-mechanisms which may be used in conjunction with the micro. switches to effect the movements of the track assembly have not been illustrated be cause it will be apparent to anyone in the art how such systems would be arranged and connected. It will be evident, however, that a reversible electric motor such as is indicated at 104 could be connected to the worm shaft 43, for example, to effect the appropriate rotary motion thereof when the respective circuits are closed. On the other hand suitable hydraulic or pneumatic means could be readily substituted for the jack screw and nut assembly as illustrated in which case the detectors would be arranged to actuate solenoids, for example, which in turn would open and close suitable valves whereby the adjusting members would be actuated to the required extent.

In the case of automatic operation, the fingers 20 of the backstop assembly would also be connected into the detector circuits so that the sheets would be tripped out of the path of the pusher blades automatically if the bottom sheet was not in proper position. The backstop assembly would be modified as shown more particularly in Figures 6 and 7 and the lever 89 would be loosely mounted on the finger supporting shaft 83 instead of being clamped thereto as heretofor described. In such case lever 89 would be provided with a laterally projecting pin 96 which would engage the depending tab 97 of a collar 98. The latter is clamped securely to the shaft 88 and is adapted to transmit motion thereto when the hand lever 93 is rocked to thereby rock the fingers 20 and lift the sheets out of the path of the pusher elements.

At the end of the finger shaft 88 is a second lever 99 having a laterally projecting pin 101 which also has coaction with the tab 97. This lever also is rotatable on the shaft 88 and has an arm 102 which projects forwardly from the shaft immediately above a solenoid 103 which is secured to the backstop bracket 81. The solenoid is connected into the detector circuit so that it will be actuated Whenever and during the entire time that either detector switch is closed so that it will rock lever 102 and thereby shaft 88 and fingers 20 to trip the sheets out of the path of the pusher elements until such time as the sheets are in proper feeding position and both circuits are opened. In this instance also it will be appreciated that other means than the solenoid, such as, for example, a pneumatic or hydraulic plunger, may be used to trip the fingers 20.

What is claimed is:

1. In a bottom sheet feeder having a reciprocating member for advancing each succeeding bottom sheet from beneath a stack of warped sheets, the combination comprising, a track assembly capable of angular adjustment for guiding said member in a path substantially normal to the radius of curvature of the sheets at the rear edge thereof, and adjustable means for varying the angular position of said assembly with relation to the radius of curvature of the sheets to thereby maintain the said normal relationship between the path of said member and the rear edge of said sheets.

2. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of Warped sheets the combination comprising, a. track assembly for guiding said carriage in a path substantially normal to the radius of curvature of the sheets at the rear edge thereof, means pivotally mounting said track assembly at the front end thereof, supporting means for the rear end of said track assembly, and adjustable means associated with said supporting 9 means for rocking said track assembly about its pivot axis relative to the radius of curvature of the sheets to thereby maintain the said normal relationship between the path of said carriage and the rear edge of said sheets.

3. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottomsheet from beneath a stack of warped sheets the combination comprising, a frame member, a track assembly mounted on said frame member for guiding said carriage in a path substantially normal to the radius of curvature of the sheets at the rear edge thereof, means pivotally mounting said track assembly at the front end thereof, adjustable supporting means connected between the frame member and the rear end of said track assembly, and manually operable means for varying the effective length of said supporting means to thereby rock said assembly about its pivot axis relative to the radius of curvature of the sheets to thereby maintain the said normal relationshi between the path of said carriage and the rear edge of said sheets.

4. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of warped sheets the combination comprising, a track assembly for guiding said carriage in a path substantially normal to the radius of curvature of said sheets at the rear edge thereof, means pivotally mounting said track assembly at the front end thereof, a support for the rear end of said track assembly, detector means for sensing the curvature of the sheets in the stack, and automatic means responsive to said detector means for varying the effective length of said support and thereby the angular position of the track assembly about its pivot axis relative to the radius of curvature of the sheets to thereby maintain the normal relationship between the path of said carriage and the rear edge of said sheets.

5. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of warped sheets the combination comprising, a frame member, a track assembly mounted on said frame member for guiding said carriage in a path substantially normal to the radius of curvature of said sheets at the rear edge thereof, means pivotally mounting said track assembly at the front end thereof, adjustable supporting means connected between the frame member and the rear end of said track assembly, adjustable means for varying the effective length of said supporting means whereby to rock the track assembly about its pivot axis relative to the radius of curvature of the sheets to thereby maintain the said normal relationship between the path of said carriage and the rear edge of the sheets, and means movable with said assembly for moving the bottom sheet out of the path of said carriage.

6. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of warped sheets the combination comprising, a support for a stack of sheets, gate means having co-action with said support to define an opening through which the bottom sheet only may pass, a track assembly for guiding said carriage in a path substantially normal to the radius of curvature of said sheets at the rear edge thereof, means pivotally mounting said track assembly at its front end, an adjustable member for supporting the rear end of said assembly, and means for adjusting the effective length of said member to thereby vary the angular position of said assembly and therewith said stack support about its pivot axis relative to the radius of curvature of the sheets to position the front edge of the bottom sheet adjacent said opening and to maintain the said normal relationship between the path of said carriage and the rear edge of the sheets.

7. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of warped sheets the combination comprising, a support for the front edge of the stack of sheets, gate means having co-actionwith said supportjto define an opening through which the bottom sheet only may pass, a bracket for supporting the rear edge ofthe stack, a track assembly for guiding said carriage inla path substantially normal to the radius of curvature of the sheets at the rear edge thereof, means pivotally mounting said track assembly at its frontend,said bracket being secured to said assembly, an adjustable member for supporting the rear end of said track assembly, and means for adjusting said member to thereby vary the angular position of the track assembly and: therewith said bracket about its pivot axis relative to the radius of curvature of the sheets whereby to locate the front edge of the bottom sheet adjacent said opening and to maintain the said normal relationship between the pathof said carriage and the rear edge of the sheets.

8. In a bottom sheet feeder having a reciprocating carriage for advancing each succeeding bottom sheet from beneath a stack of warped sheets thecombination comprising, a support for the front edge of the stack of sheets, gate means having co-action with said support to define an opening through which one sheet only may pass, a track assembly for guiding said carriage in a path substantially normal to the radius of curvature of the sheets at the rear edge thereof, means pivotally mounting said track assembly at its front end adjacent said support, a bracket for supporting the rear edge of the stack of sheets, said bracket being secured to the track assembly, an adjustable member for supporting the rear end of said assembly, means for adjusting said member and thereby said assembly and bracket about said pivot means relative to the radius of curvature of the sheets to thereby position the front edge of the bottom sheet adjacent said opening and simultaneously maintain the said normal relationship between the path of said carriage and the rear edge of the sheets, a series of elements pivotally mounted in said bracket and extending beneath the rear edge of said bottom sheet, and means for rocking said elements about their pivot axis to thereby move the rear edge of the bottom sheet out of the path of said carriage.

9. In apparatus for feeding sheets the combination comprising, a support for a stack of sheets, a member mounted for reciprocation below said stack and having elements to engage the rear edge of and to advance each succeeding bottom sheet, guide means for guiding said member in a predetermined path during its reciprocating cycle, said guide means being pivotally mounted, adjacent the front edge of said stack, and means for adjusting the guide means angularly about its pivot axis to thereby maintain the path of movement of said elements substantially normal to the radius of curvature of said sheets at the rear edge thereof.

10. In apparatus for feeding sheets the combination comprising, a' support for a stack of sheets, a carriage mounted for reciprocation below said stack, adjustable tracks for guiding said carriage in a predetermined path during its reciprocating cycle, elements on said carriage path of reciprocation of said carriage relative to the radius of curvature of the sheets to thereby maintain the direction of the force exerted by said elements against the rear edge of the sheets substantially normal to the,

radius of curvature of said sheets.

11. In apparatus for feeding warped sheets the com bination comprising, a support for a stack of sheets, a member mounted for reciprocation below said stack and adapted to engage the rear edge of and advance each succeeding bottom sheet from beneath said stack, an adjustable track assembly for guiding said member in a path substantially normal to the radius of curvatureof said sheets at the rear edge thereof, gate means at the front edge of said support defining an opening through which the bottom sheet only may pass, detector means for sensing the radius of curvature of said sheets, and means responsive to said detector means for. adjusting the angular position of said stack and therewith said track assembly with relation to said radius of curvature to thereby position the front edge of the bottom sheet adjacent said opening and simultaneously maintain the said normal relationship between said path and the rear edge of said sheet.

12. In apparatus for feeding Warped sheets the combination comprising, a support for a stack of sheets, a member mounted for reciprocation below said stack and adapted to engage the rear edge of and advance each succeeding bottom sheet from beneath said stack, an adjustable track assembly for guiding said member in a path substantially normal to the radius of curvature of said sheets at the rear edge thereof, gate means at the front edge of said support defining an opening through which the bottom sheet only may pass, detector means for sensing the curvature of said sheets, automatic means responsive to said detector means for adjusting the angular position of said stack and therewith said track assembly relative to said radius of curvature to position the front edge of the bottom sheet adjacent said opening and simultaneously maintain the said normal relationship between said path and the rear edge of said sheets, and means also responsive to said detector means for tripping the rear edge of the bottom sheet out of the path of said member if the front edge thereof is not adjacent said opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,902,280 Shields Sept. 1, 1959 FOREIGN PATENTS 730,953 Great Britain June 1, 1955

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