US3379433A

US3379433A - Sheet feeding mechanism

Info

Publication number: US3379433A
Application number: US527582A
Authority: US
Inventors: Gates Albert George Ronald
Original assignee: NRG Manufacturing Ltd
Current assignee: NRG Manufacturing Ltd
Priority date: 1965-02-16
Filing date: 1966-02-15
Publication date: 1968-04-23
Anticipated expiration: 1985-04-23
Also published as: DK124601B; AT282661B; GB1090202A

Description

A. G. R. GATES April 23, 1968 SHEET FEEDING MECHANISM Filed Feb. 15, 1966 4 Sheets-Sheet 1 In penfor WZG6FMM A ttorneys April 1968 I A. G. R. GATES 3,379,433

SHEET FEEDING MECHANISM Filed Feb. 15, 1966 4 Sheets-Sheet 2 Inventor Attorneys April 23, 1968 A, G. R. GATES 3,379,433

v SHEET FEEDING MECHANISM 11-211 Feb. 15, 1966 I Sheets-Sheet 5 lnvenlor Attorney;

Ap 1968 A. G. R. GATES 3,379,433

SHEET FEEDING MECHANISM Filed Feb. 15, 1966 v I 4 Sheets-Sheet I 35 'Ijl. h i 36 7 45 Inventor Attorneys ire ABSTRACT 0F THE DESELQSURE The invention provides, in a sheet feeding mechanism of the kind in v ieh a feed element repetitively executes 3 a movement having a forward stroke in which it advances the uppermost sheet of a stack of sheets to be fed and a rearward stroke in which it returns to its original position, a stack holding member located rearwardly of the feed element for engaging the rear end of the top of the q stack and synchronised with the movement of the feed element so as to move into engaging position after the feed element has commenced each forward feeding stroke, but befor this stroke is completed, and to disengage from the stack before the next forward feeding stroke of the feed element occurs, the stack holding member being carried by a support structure and forming with the latter an attachment which fits on the mechanism by simply resting thereon under gravity so as to be readily removable from the mechanism by lifting, the stack holding member normally resting on the stack, but being lifted therefrom at the appropriate time by the interaction of means on the mechanism and attachment.

This invention concerns improvements in or relating to sheet feeding mechanisms and more particularly to mechanisms adapted to feed sheets of paper or the like one by one from the top of a stack.

Such mechanisms are used in many different kinds of machines, examples being stencil and other duplicating machines, printing machines wrapping and packaging machines, and usually employ a feed finger or element which, in use of the mechanism, repetitively executes a movement having a forward stroke in which it pushes the uppermost sheet of a stack to a forwarding roller or other element, which receives the sheet and passes or carries it along another part of its path through the machine, and a rearward stroke in which it returns to its original position ready to move forward the next sheet which has new become the uppermost sheet of the stack. In one well-known form of feed mechanism used in stencil and other duplicating machines, the feed finger or element in its forward stroke bears down on the uppermost sheet of the st ck and then lifts from the sheetso as to be raised from the stack during the rearward stroke. In another, the feed element is a roller which reciprocates over the top of the stack and engages the latter during both the forward and rearward strokes. However, the roller is locked against rotation during the forward stroke so as then to apply forwarding pressure to the uppermost sheet of the stack, but is allowed to rotate freely on the rearward stroke so as not to move the next sheet rearwardly during this rearward stroke.

A problem encountered in such sheet feeding mechanisms when feeding some types of paper is that of ensuring that only one sheet is fed at a time, ie. that one or more sheets below the top sheet are not carried along with the latter, and known mechanisms cannot satisfactorily feed one by one from a stack, papers of weights in States Patent 0 M 3,379,433 Patented Apr. 23, 1968 a wide ran e without providing relatively complex means for adjustii the mechanisms, e.g. by adjusting the pressure with which the feed element bears on the stack.

When, in feeding of sheets by a feed element, more than one sheet is tending to be fed, there is generally some measure of displacement between the sheets being moved, the uppermost sheet being moved a little further forward than the one below which in turn is moved a little further forward than the one below that and so on. The provision of a holding member which moves synchronously with the feed element to bear on the rear end of the top of the stack after the feed element has commenced its for /arr] stroke enables the sheets below the topmost sheet to be held down by such member before they have moved forwardly any appreciable distance and the remainder of the forward stroke of the feed member causes only the topmost sheet to be moved fully forwardly.

It is an otject of this invention to provide an improved stack holdi member arrangement.

The sheet feeding mechanism of this invention comprises a feed element repetitively movable over the top of a stack of sheets to be fed in a cycle including a sheet forwarding stroke followed by a return stroke, a stack Q holding member located rearwardly of the feed element in a position to engage the rear end of the top of the stack, a support structure carrying such stack holding member, guide means receiving said support structure and guiding the latter for vertical movement, the support m ans and stack holding member carried thereby simoly resting in the mechanism under gravity and being together removable from the mechanism simply by lifting the support means out of said guide means, and means synchronised with the movement of the feed element and acting to raise the support structure and stack holding member before the commencement of each forward feeding stroke of the feed element and to allow the support structure and stack holding member to drop down again during such strok Preferably, according to a further feature of the invention, the said holding member is mounted so as to be adjustable in distance from the feed clement so as to be usable with stacks of different sizes of sheet.

The means by which movement of the holding member is synchronised with movement of the feed eleme may comprise any suitable mechanical, pneumatic or eiectrical control mechanism. In a preferred construction, the movement of the holding member is controlled by a cam.

in order that the invention may more readily be understood, two embodiments of sheet feeding mechanism according to the invention will now be described with reference to the accompanying drawings, in which:

'IGURE l'is a schematic side elevation of the first embodiment of sheet feeding mechanism according to the invention, vith part broken away for clarity;

FIGURE 2 is a view similar to that of FIGURE 1, but of the second embodiment of sheet feeding mechanism according to the invention;

FIGURE 3 is a sectional view on the line 3-3 of FIG- URE 2, with the part of the mechanism which would in this view be behind the holding member, its support rod and sliding block being omitted for clarity;

FIGURE 4 is a fragmentary side elevation of the op erating cam for the holding member of the embodiment of FIGURE 2;

FIGURE 5 is a fragmentary section on the line 5'-5 of FIGURE 4; and

FIGURE 6 is a fragmentary section on the line 65 of FIGURE 4.

The embodiment illustrated in FIGURE 1 is a sheet feeder for a twin cylinder stencil duplicator and comprises one form of conventional feed finger 1 carried by a mounting 2. In operation of the duplicator the feed finger is moved around a path comprising a feeding stroke in which it is in a lowered position (as shown in FIG- URE l) engaging the top of the stack of sheets to be fed, indicated by the reference 3, and moves in a forward direction to feed the top sheet and a return stroke in which it is in a raised position and moves rearwardly ready to descend and engage the next sheet. The movement of such feed finger is controlled from a shaft driven by the motor of the duplicator and is synchronised with the rotation of the main shaft driving the cylinders of the stencil duplicator so that one sheet is fed for each pass of the stencil in the duplicator. The mechanism for moving the feed finger 1 is conventional and is not illustrated. It is conveniently of the kind in which the finger is supported by a link system enabling both up and down and forward and rearward movement to be imparted to the finger and the said shaft controlling the movement of the feed finger carries two cams, one of which imparts a vertical component of movement to the said link system and the other of which imparts a forward and rearward component of motion to such system.

The sheet feeder also includes, according to this invention, a holding member or weight 4- spaced rearwardly from the feed finger 1. This holding member t projects longitudinally outwardly from the lower end of a supporting arm 5 which depends from the outer end of an arm system 6 carried by a bracket 7 mounted on the outside of mounting 2 for guided vertical movement by means of rollers 8 engaged in guides 9. As shown, the arm system 6 comprises three arms, the first arm being secured on top of bracket 7, the second arm being of smaller transverse dimensions and slidable within said first arm and the third arm by which the arm 5 is secured being of still smaller transverse dimensions and slidable within the second arm, the three arms thereby forming a system in which one arm telescopes into the next arm enabling the distance of the member 4 from the feed finger 1 to be adjusted. The guides 9 are provided on the inner surface of a side plate (not shown) of the duplicator behind which side plate the mechanism illustrated in the figure is located. Thus, although the guides 9 are indicated in the figure, they would in fact be above the plane of the figure.

Raising and lowering of the bracket 7 and consequently of the member 4 is controlled by a cam 19 rotatable on a shaft 11 which may be the shaft controlling movement of the feed finger or another shaft driven by the motor I of the duplicator. The cam 1t) engages a follower 12 on the bracket 7. The connection of the member 4 to the arm 5 isby means of a joint 13 enabling swinging of the member 4 in a horizontal plane relatively to the arm 5 through an angle greater than 180 so that, even though the telescoping arm system 6 may not give sufiicicnt adjustment to enable the member 4, when in the orientation shown in FIGURE 1, to approach close enough to the feed finger 1 to be engageable with very short sheets, swinging of the member 4 relatively to the arm 5 will enable such member to approach more closely to the feed (finger.

The holding member 4 carries a downwardly rojecting back stop 14 for engaging the rear of the stack of sheets and also has on its under surface two rubber pads 15, one to each side of the back stop 14.

The sheet feeder also has associated therewith a conventional front stop 16 which is adapted to engage the forward end of the stack 3 and is pivotal about an axis 17 parallel to such forward end and located a short distance below the upper surface of the stack. The front stop 16 projects from a slot 18 in a front plate 19 against which the front of the stack engages. Pivoting of the front stop 16 is controlled by a cam on a shaft rotatable in synchronism with the shaft 11 so that the stop 16 moves between a blocking position and an out-of-the-way position in synchronism with the movement of the feed finger as is explained below.

Conveniently, the assembly of holding member 4 together with its associated parts 14 and 15, arm 5, telescoping arm system 6, bracket 7, rollers S and cam assembly 19 and 12 is repeated on the other side of the mounting 2.

In use of the embodiment shown in FIGURE 1, the telescoping arm system 6 and the angular position of the ember 4 are adjusted to suit the size of sheet forming the stack 3 to be fed so that, in the lowered position of the member 4, the back stop 14 abuts the rear of the stack and the appropriate pad 15 engages the rear of the top of the stack.

The shapes of the cams controlling movement of the member 4 and front stop 16 are such that the operation of the mechanism of FIGURE 1 is as follows:

At the commencement of the feeding stroke of the feed finger 1 the front stop 16 is in its blocking position as shown in FIGURE 1 engaging the front edge of the stack and the member 4 is in its raised position. The feed finger 1 contacts the upper surface of the uppermost sheet of the stack and starts its forward movement. This moves the top sheet forwardly and it is buckled against the front stop 16, the tail of the sheet moving beyond the position of the forward rubber pad 15. At this point the member 4 descends and such pad 15 engages the rear end of the second sheet of the stack, thus preventing any movement, or any further movement, of such sheet and the sheets below. The front stop 16 then swings forwardly about its axis 17 to its out-of-the-way position and allows the top sheet to be fed forwardly during the remainder of the feeding stroke of the feed finger. When the sheet has been taken up by the part of the machine to which it is being fed, in this case the cylinders of the stencil duplicator, the feed finger 1 and the member 4 lift from the stack and the front stop 16 swings back into its blocking position at the same time engaging the front edges of the top few sheets of the stack and correcting any disturbance of such sheets which. may have taken place during the first part of the feeding stroke of the feed finger before the member 4 descended. The feed finger moves rearwardly in the raised position to its original location and the cycle above described is repeated.

The embodiment illustrated in FIGURES 2 to 6 is also a sheet feeder for a twin cylinder stencil duplicator and operates in a similar way to that of FIGURE 1, but differs from the first embodiment in the construction of the holding member and its supporting means and in the form of the cam arrangement for raising and lowering the holding member. In FIGURES 2 to 6, the same reference numerals as have been used in FIGURE 1 are used for the parts which are identical with those in FIGURE 1.

In the embodiment of FIGURES 2 to 6, the sheet feeder comprises a holding member 20, conveniently formed of that material known as Mazak, slidable on the lower limb 21 of a cranked support rod 22 conveniently formed of steel, and carried by a block 23, preferably of an acetal resin, slidab-ly mounted on two parallel rods 24, conveniently of polished steel. Movement of the block 23 along the rods 24 provides for adjustment of the holding member 20 forwardly and rear- J wardly of the mechanism, while adjustment of the member transversely of the mechanism is provided by sliding of the member on limb 21 of support rod 22 To enable securing of the block 23 in any adjusted position along the rods 24, the block carries a cam clamp 25 comprising a locking lever 26 formed integrally with a cam 27 located between the rods 24- and pivotal on an axis which is provided by a bolt 28 and is parallel to the rods 24. The shape of the cam 27 is such that, in one position, its periphery is out of contact with the rods 24, but, by moving the locking lever 26 downwardly, the periphery can be forced against the rods 24 as shown in FIGURE 3 with a Wedging action. To enable securing of the member in any adjusted position along limb 21, the member has a grub screw 29 engageable against the limb 21. The holding member is provided with a back stop 30 to engage the rear edge of the stack 3 and a rubber pad 31 to engage the rear edge of the sheet below the uppermost sheet. In FIGURE 2 the holding member is shown in its lower position. To maintain the rods 24 at their correct spacing at the rear of the mechanism, the rear ends of the rods 24 are joined by a member 32.

The forward ends of the rods 24 are received in recesses in a block 33, conveniently formed of Mazak, which block is located between the side plate 34 of the duplicator and the mounting 2. The block 33 is guided for vertical move ment by two flanged studs 35 engaging in grooves 36 in the block. The block 33 has therein a further groove 37 into which projects a pin or peg 38 carried at one end of a C-shaped lever 39. This lever is located outside the side plate 34 and is pivoted at its other end at 40, the peg 38 passing through an aperture in the side plate 34. The lever 39 is coupled to a link 41 which carries a follower 42 engaging a cam 43 secured to a sleeve 44 rotatable on the shaft 11. On the side of the block 33 adjacent the side plate 34 is secured a plate 45 adjustable, by means of the screw 46, in vertical position on the block. The lower edge of the plate 45 extends across the groove 37 into which peg 38 projects and as far as the peg 38 is concerned defines the upper limit of such groove. The block 33 rests by means of the edge of plate 45 on the peg 38. Adjustment of the plate 45 adjusts the vertical height of the stop 20. Rotation of the cam 43 causes raising and lowering of peg 38 which in turn causes raising and lowering of the block 33 and, with it, the member 20.

The operation of the mechanism of FIGURES 2 to 6 is very similar to that of FIGURE 1. Thus, at the commencement of the feeding stroke the front stop 16 is in its blocking position. The feed finger then contacts the upper surfaces of the uppermost stack and starts its forward movement. This moves the top sheet forwardly and it is buckled against the first stop 16. At this point the holding member descends and the pad 31 engages the rear end of the second sheet of the stack. This is the condition illustrated in FIGURE 2. The front stop 16 then swings forwardly and the top sheet is fed forwardly during the remainder of the forwarding stroke of the feed finger. After feeding of the sheet, the feed finger and holding member lift from the stack and the front stop swings back into its blocking position.

An advantage possessed by both of the constructions described above is that the assembly of the holding member and its associated support structure i.e. the assembly of

parts

4, 13, 14, 15, 5, 6, 7, 8 and 12 of the embodiment of FIGURE 1 and the assembly of

parts

20, 29, 30, 31, 22, 23, 26, 27, 28, 24, 33, 45 and 46 of the embodiment of FIGURES 2 to 6, is readily removable as a unit from the machine. As indicated, the holding member is only necessary for some types of paper and the ready removability of said assembly enables it to be used only when necessary.

I claim:

1. A sheet feeding mechanism comprising a feed element repetitively movable over the top of a stack of sheets to be fed in a cycle including a sheet forwarding stroke followed by a return stroke, a stack holding member located rearwardly of the feed element in a position to engage the rear end of the top of the stack, a support structure carrying such stack holding member, guide means receiving said support structure and guiding the latter for vertical movement, the support means and stack holding member carried thereby simply resting in the mechanism under gravity and being together removable rom the mechanism simply by lifting the support means out of said guide means, and means synchronised with the movement of the feed element and acting to raise the support structure and stack holding member before the commencement of each forward feeding stroke of the feed element and to allow the support structure and stack holding member to drop down again during such stroke.

2. The sheet feeding mechanism specified in claim 1 and including a rotatable earn, a follower engaging said cam, a bracket guided for vertical movement, said follower being mounted on said bracket, and a support carried by said bracket and carrying said holding member.

3. The sheet feeding mechanism specified in claim 1 and including a rotatable cam, a lever pivoted at one end adjacent said cam, a follower engaging said cam and coupled to said lever so as, on rotation of the cam, to cause up and down movement of the end of the lever remote from its pivoted end, a pin mounted on the end of the lever remote from its pivoted end, a support block guided for vertical movement and having a vertically extending slot therein, said pin engaging in said slot, and a support carried by said support block and carrying said holding member.

4. The sheet feeding mechanism specified in claim 3 and including a plate adjustably secured to said support block, a lower edge of said plate extending across said slot and resting on said pin.

5. The sheet feeding mechanism specified in claim 1, in which said support structure includes means for varying the distance of the holding member from the feed element.

6. The sheet feeding mechanism specified in claim 5, in which said means comprises a telescoping arm system extending in the direction of feed of the mechanism and a dependent arm carried by said system and itself carrying said holding member.

7. The sheet feeding mechanism specified in claim 6, and including a pivotal joint between said dependent arm and said holding member allowing pivoting of the latter transversely of the mechanism.

8. The sheet feeding mechanism specified in claim 5, in which said means comprises a pair of parallel rods extending in the direction of feed of the mechanism, a block slidable on said rods and a dependent arm carried by said block and itself carrying said holding member.

9. The sheet feeding mechanism specified in claim 8, and including a cam clamp on said block between said parallel rods.

10. The sheet feeding mechanism specified in claim 8, and including a transversely extending limb on said dependent arm, said holding member being slidable on said limb, and a locking means on said holding member and engageable with said limb effective to lock the holding member on the latter.

References Cited UNITED STATES PATENTS 959,319 5/1910 Dexter 271-42 1,599,153 9/1926 Weightman 271-43 EDWARD A. SROKA, Primary Examiner.