US3484099A

US3484099A - Rotary sheet feeding and separating assembly

Info

Publication number: US3484099A
Application number: US633865A
Authority: US
Inventors: John P Gallagher
Original assignee: AB Dick Co
Current assignee: AB Dick Co
Priority date: 1967-04-26
Filing date: 1967-04-26
Publication date: 1969-12-16
Anticipated expiration: 1986-12-16
Also published as: DE1611346B1; GB1183877A

Description

Dec. 36, 1969 J. P. GALLAGHER 3,484,999

ROTARY SHEET FEEDING AND SEPARATING ASSEMBLY 2 Sheets-Sheet 1 Filed April 26, 1967 R O m V m ATTORNEY ROTARY SHEET FEEDING AND SEPARATING ASSEMBLY Filed April 26, 1967 Dec. 16, 1969 J. P. GALLAGHER 2 Sheets-Sheet 2 INVENTOR JOHN Pv GALLAGHER BY Q M ATTORNEY United States Patent US. Cl. 271-51 4 Claims ABSTRACT OF THE DISCLOSURE The rotary sheet feeding and separating assembly in cludes a circular feed roller centered above a contacting separator roller and flanked on either side by circular sheet gripper rollers. The sheet gripper rollers, with the feed roller, are positively driven and are adapted to feed sheets directly into forwarding rollers rotating at a speed greater than that of the feed and gripper rollers. The gripper rollers include resilient teeth formed to increase the contact pressure with a sheet being fed when sheet drag or roller slippage occurs and to release such sheet when it is gripped by the forwarding rollers.

The present invention relates to sheet feeding and separating devices generally, and more particularly to a novel rotary sheet feeding and separating assembly for feeding individual sheets from a sheet stack.

Recent advances in duplicator technology have resulted in the development of a variety of high speed duplicating machines. Many of these machines are automatically programmed to perform a number of duplicating functions which may require the machine to be rapidly provided with sheet material from a supply stack. In some instances, the individual sheets within the supply stack may have diverse physical characteristics which differentiate individual sheets within the stack from other sheets.

Modern duplicating machines often require a sheet feeding and separating mechanism capable of operating rapidly and effectively to provide the sheet requirement for high speed operation. Among the non-rotating sheet separator mechanisms known to the prior art are friction retaining pads for the sides of a sheet stack and corner separator fingers operative upon the front edges of a sheet stack. These separator mechanisms must necessarily operate in conjunction with a separate sheet feeding mechanism, and are subject to limitations which render them unsuitable for some duplicating applications.

The rotating sheet feeding and separating units previously known have normally included a pair of contacting roller members which operate to separate single sheets from a supply stack by permitting only one sheet at a time to pass between the nip of the rollers. For some applications, these rotating separator members prove completely acceptable, but often, such separator and feeding mechanisms do not meet the requirements of modern high speed duplicators. For example, these mechanisms will normally not effectively feed, without adjustment, sheets of varying thicknesses or sheets having widely varying frictional characteristics. A substantial variation in sheet thickness will cause a sheet to be rejected by the roller separator, while a sheet having a loW coefficient of friction might cause the separator rollers to slip to an extent that effective sheet feeding becomes impossible.

Not only should an efficient feeding and separating mechanism be capable of feeding sheets of varying thicknesses and frictional characteristics, but also, it is often desirable to feed a sheet directly into a forwarding mechanism having a rotational speed greater than the speed of rotation of the separating and feeding unit. This is practically impossible to accomplish without damage to 3,484,099 Patented Dec. 16, 1969 the sheet being fed when the feeding and separating unit is of the conventional roller type which must firmly grip the sheet to produce sufficient friction for effective sheet feeding. V

It is a primary object of this invention to provide a novel and improved rotary sheet feeding and separating assembly which is capable of effectively separating and feeding a single sheet from a sheet storage stack.

Another object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly capable of operating effectively without adjustment to separate and feed a single sheet from a sheet storage stack composed of sheets of varying thickness.

A further object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly capable of operating effectively without adjustment to separate and feed a single sheet from a sheet storage sack composed of sheets having varying frictional characteristics.

Another object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly capable of operating effectively, without adjustment, to separate and feed a single sheet from a sheet storage stack composed of sheets having varying thicknesses and frictional characteristics.

A further object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly capable of separating and feeding a single sheet from a sheet storage stack at a first speed and subsequently ejecting this sheet into a sheet forwarding apparatus which is operating at a greater speed.

Another object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly for duplicating machines capable of effectively separating and feeding a single sheet from a sheet storage stack into a sheet feeding mechanism rotating at a speed greater than that of the sheet feeding and separating assembly.

A further object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly which includes sheet feeding units capable of altering the frictional contact between the sheet feeding unit and a sheet being fed in accordance with the frictional characteristics of the sheet.

A still further object of this invention is to provide a novel and improved rotary sheet feeding and separating assembly which includes a sheet feeding unit which operates to release a sheet being fed thereby upon engagement of said sheet with a sheet feeding mechanism operating at higher speeds.

The foregoing and other objects of this invention will become apparent upon a consideration and the following specification and appended claims taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a diagrammatic side elevational view of a duplicating machine equipped with the rotary sheet feeding and separating assembly of the present invention;

FIGURE 2 is a fragmentary perspective view illustrating the major components of the rotary sheet feeding and separating assembly of FIG. 1;

FIGURE 3 is a diagrammatic view illustrating the sheet gripper roller of the present invention; and

FIGURE 4 is a fragmentary perspective view illustrating an embodiment of the rotary sheet feeding and separating assembly of the present invention.

The rotary sheet feeding and separating assembly indicated generally at 10 in FIGS. 1 and 2 may be effectively employed with a wide variety of duplicating or other machines which require that a single sheet be rapidly fed into the machine from a sheet supply stack. In FIG. 1, the assembly of this invention is illustrated in use as a master sheet feeding and separating unit for an offset lithographic duplicating machine 12. This use of the rotary sheet feeding and separating assembly is considered to be particularly suitable for descriptive purposes, as it will be apparent to those skilled in the art that offset lithographic master sheets are of variable thickness and have variable frictional characteristics. It must be appreciated, however, that the rotary sheet feeding and separating assembly may be universally employed for many other applications where sheet feeding is required, and is not limited for use with lithographic master sheets.

The offset lithographic duplicating machine 12 in FIG. 1 includes a master cylinder 14, a blanket or offset cylinder 16, and an impression cylinder 18. These cylinders are mounted for rotation between'two substantially parallel side plates of the duplicating machine, one of which is indicated at 20. v

The master cylinder of the duplicating machine, as is conventional with such machines, is adapted to carry an offset master sheet which may be formed from paper or similar thin sheet material. In operation, a clamp (not shown) is provided on the surface of the master cylinder to receive and clamp the leading edge of the master sheet in order to retain the sheet on the cylinder.

For illustrative puposes in FIG. 1, the sheet feeding and separating assembly 10 is mounted upon the side plates of the duplicating machine and is positioned to separate and feed master sheets 22 from a sheet storage tray 24 to the master cylinder 14. To accomplish this purpose, the sheet feeding and separating assembly must be capable of separating and forwarding master sheets of varying thicknesses and frictional characteristics. Additionally, the assembly must also remove an individual master sheet from the tray 24 at one speed and subsequently increase the forwarding speed of such master sheet so that it reaches the clamp on the master cylinder 14 at a speed corresponding substantially to the rotational speed of the master cylinder.

The sheet feeding and separating assembly 10 includes two

sheet gripper rollers

26 and 28 which are mounted in substantially parallel, spaced relationship upon a roller drive shaft 30. A resilient sheet feed roller 32 is mounted upon the shaft 30 between the

gripper rollers

26 and 28. While the diameter of the two gripper rollers is substantially equal, the diameter of the sheet feed roller 32 should be slightly less than that of the gripper rollers.

The

rollers

26, 28 and 32 are secured against rotation relative to the shaft 30 which extends through the center of the rollers, and to accomplish this purpose, any suitable roller mounting means may be employed. In FIG. 2,.the

gripper rollers

26 and 28 are mounted upon the

shaft'by roller hubs

34 and 36 having set screws 38 and 40 which engage the shaft, while the feed roller 32 is mounted upon the shaft by a set screw 42. Thus, when the shaft 30 is driven by a gear 44 containing an overrunning clutch 46 fixed to one end thereof and by a gear 48 connected to any suitable drive means (not shown), the

rollers

26, 28 and 32 are positively driven.

Centered beneath the feed roller 32 is a separator roller 50 which is mounted upon a frame 52 by means of a shaft 54. The shaft 54 may constitute the shank of a locking screw 56 which is employed to lock the separator roller against rotation within the frame.

The frame 52 is formed to provide arcuate surfaces on either side of the separator roller 50 which fall beneath the

gripper rollers

26 and 28. These arcuate surfaces conform substantially in shape to the outside circumference of the separator roller. In FIG. 2, by

leaf springs

58 and 60 which are mounted beneath the

gripper rollers

26 and 28 but to the side of the frame 52 the leaf springs are bowed upwardly toward the

gripper rollers

26 and 28.

The frame 52 is pivotally secured to a mounting post 62'which is in turn attached to a stationary support for the frame. An adjusting screw 64 extends through the frame at the end opposite the mounting post 62, and v this adjusting screw is then received in a suitable receptacle provided in a stationary sup-port for the frame. This permits the frame to be pivoted relative to the mounting post 62 by adjusting the adjusting screw 64 so that the pressure between the feed roller 32 and separator roller 50 can be varied. In FIG. 1, the mounting post 62 is attached to the bottom surface of a stationary sheet guide secured between the side plates of the duplicating machine. The adjusting screw 64 also projects into a suitably threaded receptacle on the bottom portion of the sheet guide to permit adjustment of the separator roller, relative to the feed roller; The separator roller. extends through an opening inthe sheet. guide into contact with thefeed roller. v i

The

gripper rollers

26 and 28, the feed roller 32 and the separator roller 50 are particularly-designed to operate with high speed forwarding'rollers which are spaced toreceive and forward a sheet afterthe forward edge thereof has passed between the

rollers

32 and 50. These high speed forwarding rollers are driven independently of the

rollers

26, 28 and 32-.at a rotational speed which is greater than the speed of such rollers. In some cases, the sheet forwarding rollers may constitute an integral part of a machine with which the feed, gripper, and separator rollers are removably associated, as will be subsequently described, or all of the rollers of the rotary sheet feeding and separating assembly 10 may be included as an integral unit of a machine as illustrated in FIG. 1.

The forwarding rollers may be combined in any suitable forwarding assembly, and constitute upper rollers 68 and lower rollers 70. Either group of rollers may be positively driven, but for purposes of illustration, lower rollers 70 are mounted upon a shaft 72 which is driven by a suitable drive source (not shown). The shaft 72 and the rollers 70 are driven at a speed which is greater than the driving speed provided by the drive source for the gear 48, so that the forwarding

rollers

68 and 70 are rotating at a greater speed than the

rollers

26, 28 and 32.

The forwarding

rollers

68 and 70 may be employed in conjunction with a sheet guide assembly including an upper guide 74 and a lower guide 76 spaced therefrom. These upper and lower guides are suitably mounted upon a support for the rotary sheet feeding and separating assembly 10, and, as illustrated by FIG. 1, are secured to the side plates of the duplicating machine 12. For some applications, the upper guide may be pivoted relative to a support by a pivotal arm 78 so that the upper forwarding rollers 68 may be pivoted into and away from contact with the lower'driven forwarding rollers 70. The upper forwarding rollers 68 may be adjustably mounted upon the guide 74 by means of adjustable mounting units 80. 1

It will be apparent that the unit containing the forwarding

rollers

68 and 70 may be of any desirable configuration, and the unit illustrated in FIG. 2 is provided merely for descriptive purposes. However, for the forwarding

rollers

68 and 70 to operate to forward a sheet from the

rollers

26, 28 and 32 at a greater speed than that at which such sheet was drawn from supply stack, the forwarding rollers should be positioned to receive the leading edge of the sheet while the trailing portion of the same sheet is still passing between the

rollers

32 and 50.

The structure and configuration of the

gripper rollers

26 and 28 are quite important to the sheet feeding and separating assembly, and these rollers are worthy of consideration'in greater detail. With reference to FIGS. 2 and 3, it will be noted that the grip-per

rollers

26 and 28 are circular rollers having spaced slots 82 formed therein to define a plurality ofspaced teeth 84 which form the circumferential bearing surface of the roller. Each tooth 84 has a leading edge 86, a trailing edge 88, and a hearing surface extending between the leading and trailing edges of the tooth. The construction of these teeth enables them to perform novel and improved sheet feeding functions during the operation of the sheet feeding and separating assembly.

The

gripper rollers

26 and 28 are formed from elastomeric material so that the teeth 84 thereof are resilient. The gripper rollers are mounted so that as the teeth contact the sheet being fed, the slots separating the contacting teeth are inclined rearwardly away from the direction of feed. The extremities of the inclined slots are defined by'the trailing edge 88 and the leading edge 86 of adjacent teeth 84. For proper operation of the gripper rollers, the trailing edge of each tooth should be formed to provide an angle which is within a range of from to 60 with a radial line A passing through the innermost extremity of the trailing edge. This angular relationship is illustrated in the diagrammatic representation of FIG. 3.

The leading edges 86 of the teeth 84 may be formed parallel with the trailing edges of adjacent teeth, as illustrated in FIG. 3, but it is always desirable to have the leading edges of the teeth formed to an angle whereby a toe portion of the tooth bearingsurface 90, indicated at 92 in FIG. 3, will always extend beyond a radial line B drawn through the innermost extremity of the leading edge. Additionally, the leading edge of each tooth may be provided with a flat ridge 94 adjacent the bearing surface 90 to aid the gripper roller in gripping a sheet as it is removed from a sheet stack and fed forward by the roller.

The diagrammatic view of the gripper roller 26 in FIG. 3 has been somewhat exaggerated for descriptive purposes to provide a clear indication of the operation of the gripper rollers. It will be noted that the teeth 84 of the gripper roller are not pointed teeth, but instead are in the shape of relatively blunt feeder feet having a definite bearing surface 90 extending from the trailing edge of the tooth to the leading edge. The portion 92 of the bearing surface forms the toe for the feeder foot and operates to permit a tooth to automatically alter its frictional contact with a sheet being fed. For example, should a sheet to be gripped by the gripper roller have a glossy surface or a similar low friction surface, it will be apparent that a feed roller having pointed teeth or having a smooth, round surface, will slip on the low friction surface of the sheet. In some instances, rollers of this type will completely fail to feed a sheet with a low friction surface unless an adjustment is made to increase the roller contact pressure.

The gripper rollers of the present invention automatically vary the contact presure between the bearing surfaces 90 and sheets of varying frictional characteristics. As the gripper roller begins to slip relative to a sheet being fed, the tooth contacting such sheet begins to pivot rearwardly about a fulcrum point 96 at the innermost extremity of the leading edge of such tooth. The flexing of the tooth about the fulcrum causes the bearing surface toe 92 to move downwardly into an increased pressure contact with the sheet being fed, a indicated by the dotted lines in FIG. 3, and greater contact pressure is developed. The further the tooth 84 flexes in the rearward direction, the greater will be the contact pressure between the tooth and the sheet being fed, and in some instances, the flat leading edge portion 94 of the tooth is driven against the sheet with considerable pressure. Thus, the teeth of the gripper rollers operae effectively to feed sheets having diverse frictional characteristics and roller slippage is minimized.

Not only are the roller teeth 84 designed to automatically increase contact pressure to resist roller slippage or sheet drag, but also the teeth are designed to provide minimal resistance to the withdrawal of a sheet from beneath the gripper rollers in a forward direction. For example, with reference to FIGS. 2 and 3, as the leading edge of a sheet is gripped by the forwarding

rollers

68 and 70, it will become apparent that the greater speed of rotation of these rollers will cause the sheet to be forceably withdrawn from beneath the

gripper rollers

26 and 28. However, when this rapid forward movement of the sheet occurs, the teeth 84 in contact with the sheet will flex in a forward direction about the fulcrum point 96 to move the leading edge of the tooth toward the trailing edge of the preceding tooth. The inclination of the slots 82 permits this forward flexure of the contact teeth to occur with minimal resistance, and the rear edge of the contact surface adjacent the trailing edge 88 of the tooth is lifted away from contact with the sheet being withdrawn, thereby decreasing the pressure exerted by the

rollers

26 and 28 upon the sheet. It is interesting to note that this releasing action of the teeth 84 is similar to the action which would occur if a feeder roller having pointed teeth, rather than teeth with a toe section 92, begins to slip relative to a sheet being fed.

Thus, it is apparent that the gripper rollers of this invention are highly resistant to sheet-roller slippage in the feed direction, and automatically increase roller contact pressure to overcome any sheet resistance which opposes feeding. However, the gripper rollers are also operative to provide minimal resistance to the rapid withdraw of a sheet in the direction of sheet feeding.

From a consideration of the foregoing description, the operation of the sheet feeding and separating assembly of the present invention will become apparent. With the assembly in place upon a machine, the feed roller 32 is centered above the separator roller 50, and the separator roller is locked against rotation by the locking screw 56. The pressure regulating screw 64 is adjusted to pivot the frame 52 relative to the post 62 until the separator roller just contacts the feed roller. This adjustment of the nip between the separator and feed rollers operates to permit only a single sheet from a sheet stack to pass between the rollers. However, as the feed roller 32 is formed from elastomeric material, as are the

gripper rollers

26 and 28, sheets of varying thickness are permitted to be individually fed between the feed and separator rollers without readjusting the gap between such rollers.

As the

rollers

26, 32 and 28 are rotated by the drive gear 48, the gripper rollers grip sheets from the stack 22 and feed them between the separator and feed rollers. The

springs

58 and 60 urge the outer portions of each sheet upwardly into contact with the

gripper rollers

26 and 28, while the center portion of the sheet passes into the nip between the separator and feed rollers. If the gripper rollers begin to slip relative to the sheet, the teeth 84 thereof flex rearwardly to increase the contact pressure with the sheet, and the sheet is positively fed until the leading edge passes between the forwarding

rollers

68 and 70. At this point, the forwarding rollers increase the speed of the sheet in the feed direction, and the teeth of the gripper rollers flex forwardly to permit the sheet to be withdrawn therefrom. Thus, the feeding of the sheet is continued by the forwarding rollers at a greater speed than that previously imparted to the sheet by the gripper rollers.

FIG. 4 illustrates an embodiment of the sheet feeding and separating assembly of the present invention wherein the unit including the

gripper rollers

26 and 28, the feed roller 32, and the separator roller 50 is mounted upon a feed table 98. The feed table may, in turn, be removably mounted upon a duplicaing machine or other machine which is to receive supply sheets from a stack provided on the feed table.

The feed table 98 is similar in construction to feed tables known to the prior art, and includes a flat platform or bed 100 for supporting a stack of sheets. Side rails 102 are mounted upon either side of the platform for guiding and positioning the edges of the sheet stack. These side rails may be adjustable laterally or across the feed table to adjust the position of the sheet-stack, and any suitable known adjusting mechanism may be employed to facilitate this adjustment.

The shaft 30 is mounted for rotation on the side rails 102 and is positioned thereby at the forward end of the feed table 98. It is of course obvious that stationary mounting posts may be provided at the forward end of the feed table to mount the shaft 30, and if such stationary mounting posts are employed, the side rails 102 will be positioned behind these mounting posts. However, if the shaft is mounted directly upon the side rails, this mounting must be such that lateral adjustment of the side rails is permitted.

The post 62 is secured to the underside of the platform 100, and this post pivotally supports the frame 52 for the separator roller 50 in the manner previously described. The pressure regulating knob for the separator roller extends into a suitable receptacle on the bottom of the platform 100, while the separator roller is permitted to contact the feed roller 32 by projecting through an opening 104 as are the bearing surfaces 58 and 60 for the

gripper rollers

26 and 28 which are formed on the frame 52.

When the gear 46 is driven by a suitable driving mechanism (not shown), the gripper rollers 2-6 and 28 and the feed and

separator rollers

32 and 52 operate to separate and feed individual sheets from a stack contained upon the feed table 98 in the manner previously described.

It will be readily apparent to those skilled in the art that this invention provides a novel and improved sheet feeding and separating assembly which will effectively separate and feed sheets of varying thicknesses and frictional characteristics from a sheet stack. The arrangement and types of components herein may be subject to numerous modifications well within the perview of this inventor who intends only to be limited to a broad interpretation of the specification and appended claims.

What is claimed is:

1. A rotary sheet feeding and separating assembly for feeding individual sheets from a sheet stack comprising support means, sheet separating means mounted upon said support means, and sheet feeding means mounted for rotation upon said support means above said sheet separating means to feed sheets therebetween, said sheet feeding means including gripper roller means operative to automatically vary the contact pressure on a sheet being fed thereby to overcome resistance to sheet feeding, said gripper roller means being also operative to provide minimum resistance to the withdrawal in the direction of feed of a sheet being fed thereby, said sheet feeding means including a substantially circular sheet feeder roller centered above said sheet separating means, said gripper roller means including gripper rollers mounted co-axially with said feeder roller on either side thereof, said sheet separating means including a separator roller for contact with said feeder roller, frame means for mounting said separator roller for adjustment relative to said feeder roller, said frame means including bearing surface means for said gripper rollers positioned on either side of said separator roller, said bearing surface means operating to guide a sheet into contact with said gripper rollers, said bearing surface means constituting biasing springs secured to said frame means, and said biasing springs operating to bias a sheet upwardly against said gripper rollers.

2. A rotary sheet feeding and separating assembly for feeding individual sheets from a sheet stack comprising support means, sheet separating means mounted upon said support means, means above said separating means to feed sheets therebetween, said sheet feeding means including a substantially'circular sheet feeder roller centered 8 I above said sheet separating means and a gripper roller mounted co-axially with said feeder roller on either side thereof, each of said gripper rollers having a roller body, a plurality of inclined slots formed in the periphery of said roller body to define a plurality of spaced resilient gripper teeth, each of said gripper teeth having a leading surface, a trailing surface and an outer bearing surface extending between the outer extremities of said leading and trailing surfaces, said outer bearing surface presenting a relatively blunt feeder foot, and means for mounting said gripper rollers on said support means so that the slots between gripper teeth in contact with a sheet to be fed are inclined away' from the direction of feed and the leading surface of the tooth in contact with the sheet to be fed never flexes rearwardly beyond the radial line for the feeder roller which intersects with the innermost point of said leading surface, whereby the gripper teeth will automatically vary the contact pressure on a sheet being fed thereby to overcome resistance to sheet feeding in said feed direction while also being operative to provide minimum resistance to the withdrawal in the feed direction of a sheet being fed thereby.

3. The rotary sheet feeding and separating assembly of claim 2 wherein said support means constitutes a sheet feed table for supporting a stack of sheets to be fed, said feed table including a sheet supporting platform and a pair of side rails mounted on said feed table to position and guide the lateral edges of a sheet stack on said sheet supporting platform.

4. A rotary sheet feeding assembly for feeding individual sheets supported on a supporting surface comprising a gripper roller having a roller body, a plurality of inclined slots formed in the periphery of said roller body to define a plurality of spaced resilient gripper teeth, each of said gripper teeth having a leading surface, a trailing surface, and an outer bearing surface extending between the outer extremities of said leading and trailing surfaces, said outer bearing surface presenting a relatively blunt feeder foot, and means for rotatably mounting said gripper roller above the supporting surface so that the slots between said gripper teeth in contact with a sheet to be fed are inclined away from the direction of feed, each feeder foot, under the influence of increased resistance of the sheet to being fed, flexing to permit outward extension of the feeder foot but with the leading surface of the tooth in contact with the sheet to be fed never flexing rearwardly beyond the radial line of said-feed roller which intersects with the innermost point of said leading surface, whereby said gripper teeth will automatically vary the contact pressure on a sheet being fed thereby to overcome resistance to sheet feeding in said feed direction while also being operative to provide minimum resistance to the withdrawal in the feed direction of a sheet being fed thereby.

References Cited UNITED STATES PATENTS 3,285,484 11/1966 Johnson 226l91 1,599,997 9/1926 Hansen 27137 2,762,623 9/1956 Uthenwoldt et a1. 27136 FOREIGN PATENTS 22,062 10/1900 Great Britain.

EDWARD A. SROKA, Primary Examiner U.S. Cl. X.R.