GB2033348A - Sheet feeder - Google Patents

Abstract

A method and apparatus for feeding flexible material sequentially from a stack. Each sheet is guided downwardly and fanned forwardly and retarded by friction means 32 in its forward movement except for the lowermost sheet which passes between a moving conveyor platform 18 and the friction means. The lowermost sheet is distorted arcuately from its normal plane by interaction between the platform and the friction means to effect at least partial separation between that sheet and the next succeeding sheet. The platform comprises belts 12, and the friction means is a wheel which rotates very slowly compared with the belt speed. <IMAGE>

Description

SPECIFICATION Sheet feeder This invention relates to a method and apparatus for feeding flexible sheet material sequentially from a stack onto a movable conveyor platform.

Devices have been developed for feeding sheet material, such as greeting cards, at high speed sequentially from a stack. An example machine for this purpose is described in my United States Patent No, 3,908,983 issued September 30, 1 975 entitled Card Feeder. However, such devices are suitable only for relatively thick sheet material since the sheets in a stack of thinner material tend to stick together which makes the feeding of single sheets difficult and also the pressure in the nip required for thinner sheets tends to cause the movement of the conveyor platform to smear the ink on the sheets.

Postal machine devices are known which will separate letters from a stack but such machines would not be practical for thin sheet material since the friction deterrent means would peel and crease the sheets being fed through the device. An example of such a postal machine is disclosed in United States Patent No. 1,955,066 issued April 1 7, 1954 to G. Hiller.

It is an object of the present invention to provide an improved method and device for feeding thin sheet material sequentially from a stack.

According to one aspect of the invention, we provide a method of feeding flexible material sequentially from a stack thereof, comprising the steps of; holding the stack of flexible sheets above a forwardly moving conveyor platform, the stackbeing held in a downwardly sloping position in the forward direction of travel of the platform and spaced therefrom, the lowermost sheets of the stack being fanned forwardly; retarding the forward movement of those sheets adjacent the lowermost sheet of the stack by friction means; allowing the single lowermost single sheet of the stack to move forwardly on the platform between the platform and the friction means, and distorting said lowermost sheet arcuately from its normal plane by interaction between the friction means and the platform to effect at least partial lateral separation between said lowermost sheet and the adjacent next lowermost sheet.

In another aspect the invention consists of a device for feeding flexible sheet material sequentially from a stack thereof, comprising: a conveyor providing a planar, forwardly movable platform; means to hold the stack of flexible sheets above the platform in a downwardly sloping position in the forward direction of travel of the platform and spaced therefrom, said holding means including means whereby the lowermost sheets of the stack are fanned forwardly; friction means positioned above the platform forwardly of the stack to retard the forward movement of these sheets adjacent the lowermost sheet of the stack, the friction means being spaced from the platform to allow passage of a single sheet therethrou,gh and projecting below the upper planar surface of said single sheet whereby said upper planar surface is laterally distorted arcuately to effect at least partial lateral separation of said lowermost sheet from the adjacent next lowermost sheet; means to support the platform adjacent the friction means; and means to move the platform forwardly whereby said lowermost sheet is advanced towards said friction means.

Reference is now made to the accompanying drawings in which: Figure 1 is a perspective view of a sheet material feeding device; Figure 2 is a view in cross-section taken along line 2-2 of Figure 1; and Figure 3 is a view taken along line 3-3 of Figure 2.

Figure 4 is a perspective view of an alternate embodiment of a sheet material feeding device; Figure 5 is a side view in elevation of the guide, the conveyor platform, and the friction means of the device of Figure 1 , taken adjacent the centre auxiliary band, with a stack of sheets being fed therethrough; Figure 6 is a view taken along line 3-3 of Figure 5; and Figure 7 is a cross-section taken along line 4-4 of Figure 3.

The example embodiment shown in Figures 1 to 3 of the drawings comprises a pair of journalled rollers 10, suitably driven and mounted on a frame (not shown), which carry a plurality of horizontally disposed bands 1 2 adjustable in known manner for yaw and for speed, the bands being laterally spaced to provide a gap 13. Bands 12 form a conveyor platform 1 8 movable in the direction of arrows 14 and are located between a pair of upright, spaced guide flanges 1 5 fixed on parallel, spaced guide rails 1 6 which are adjustably mounted on the frame.

A curved guide bar 20, mounted on a crossbar 22, is located above bands 1 2 and in front of guide flanges 1 5 (with respect to the direction of travel of bands 12). Crossbar 22 is fixed on a pair of lateral walls 24 mounted on the frame of the device. The upper portion of guide bar 20 forms an arm 26 sloping downwardly and rearwardly and the guide bar then curves forwardly in an arc 27 to form a horizontally disposed forwardly directed tongue 28 lying astride 13 above bands 12 to define a passage 29. Arc 27 of guide bar 20 has a centrally disposed longitudinal slot 30 extending into arm 26 and into tongue 28.

Friction means, in the form of a wheel 32, oriented in a vertical plane lying in the direction of movement of bands 12 and keyed own a shaft 34, has a rim 36 of hard rubber, or other material such as a tungsten carbide coating on steel, of a high coefficient of friction and is located in the lower portion of slot 30 of guide bar 20 adjacent bands 12. As seen more particularly in Figure 3 of the drawings, wheel 32 is so located that the periphery of rim 36 extends downwardly slightly beyond the lower surface of tongue 28 but does not extend laterally beyond the rearward surface of arm 26 or 27, i.e. only the lower portion of wheel 32 is exposed below guide bar 20.Also the bottom of friction wheel 32 lies in gap 13 between bands 12 and slightly below the plane of the upper surface of the bands, as seen in Figure 3 of the drawings, but not enough to crease the sheet material being fed by the device.

Shaft 34 isjournalled in a pair of bearings 36 mounted one on each of frame walls 24. Each bearing 36 is adjustable vertically along a pair of rails 38 by screws 40 mounted in brackets 42.

Rails 38 and brackets 42 are fixed on side walls 24 and shaft 34 extends through a slot 44 in each side wall. A sprocket 46 is keyed on shaft 34 adjacent one bearing 36 and is engaged by a chain 48 which is driven through a reducing gear (not shown) from the drive of roller 10.

Guide bar 20 may be adjustable, for example in the manner shown in Figures 5 and 6 of my United States Patent No. 3,908,983 mentioned above.

Similarly chain 48 may be tensioned in the manner shown in Figure 1 of that patent and sprocket 46 may be driven as shown in Figure 1 A or my above-mentioned patent.

A retainer bar 50, spaced behind guide bar 20, is mounted on a further crossbar 52 which is in turn mounted in known manner on lateral frame walls 24 and adjustable in the direction of movement of bands 12, for example as shown in Figure 4 of my above-mentioned United States patent No.3,908,983. Retainer bar 50 is contoured in a manner similar to arm 26 of guide bar 20 but terminates in a lower lip 54 spaced above bands 12, as seen in Figures 1 and 2 of the drawings.

In the operation of the example embodiment shown in Figures 1 to 3 of the drawings a stack 60 of cards is placed between retainer bar 50 and guide bar 20. Stack 6Q may be centered and tilted and guide bar 20 may be moved horizontally, as described in my U.S. Patent No. 3,908,983. The position of wheel 32 in slot 30 of guide bar 20 is adjustable by screws 40 which also adjust the width of gap 38 between the wheel and bands 12.

Because of the curvature of lip 54 of retainer bar 50 and arc 27 of guide bar 20, the weight of stack 60 fans the lower cards of the stack forwardly.

When these adjustments have been made the operation of the device is initiated by moving bands 1 2 in the direction of arrows 14. As the bottom or first card 61 in stack 60 is moved downwardly by the weight of the stack, the leading edge of that card touches bands 1 2 and is pulled forward by the continuous movement of the bands in the direction of arrows 14 as seen in Figures 2 and 3. The forward movement of bottom card 61 allows the trailing edge of that card to clear lip 54 of retainer bar 50 and drop onto bands 12.

As bottom card 61 passes forwardly between friction wheel 32 and bands 1 2 it is distorted arcuately from its normal plane, as seen in Figure 3 of the drawings, because the bottom of the friction wheel lies below the plane of the upper surface of the card. This effects at least partial separation between bottom card 61 and the next lowermost card 62 and prevents those two cards from sticking together and prematurely pulling card 62 from stack 60.

As the leading edge of bottom card 61 passes forwardly between friction wheel 32 and bands 12 the leading edges of the cards immediately above it in stack 60, i.e. second card 62 and third card 63, are forced forwardly by the weight of the stack and the curvature of bars 20 and 50. At this point the leading edge of card 62 comes into contact with friction wheel 32 which projects slightly below arc 27 of guide bar 20. Friction wheel 32 is geared to rotate at an extremely slow speed, say 1:3000 in relation to the speed of bands 12, and the wheel may be rotated in either direction.

Bottom card 61 continues to be carried forward by bands 12, affected only the friction of the leading edge of card 62 which keeps it clear of friction wheel 32, and is carried forward by the bands through passage 29 between the bands and tongue 28 of guide bar 20, to be delivered by the bands to a subsequent station. When card 61 has passed friction wheel 32 and bands 12 the leading edge of the next card 62 drops onto bands 12 and is carried forward, causing the trailing edge of card 62 to clear lip 54 of retainer bar 50, whereupon card 62 passes friction wheel and bands 1 2 and through passage 29 in the same manner.

In the example embodiment shown in Figures 4 to 7 of the drawings an endless auxiliary band 70 is located between a pair of endless primary bands 72 which form a conveyor platform 74. Primary bands 72 pass around a pair of front pulleys 76 and a pair of rear pulleys 78, both pairs of pulleys being preferably of the same diameter. Front pulleys 76 are fixed on a front drive shaft 80 journally mounted in side frame 24 and suitably driven while rear pulleys 78 are fixed on a rear driven shaft 82 also journally mounted in side frame 24. Rear shaft 82 is driven from front shaft 80 through a further belt and pulley arrangement 84 located on each side of pulleys 76 and 78 (see Figure 4). Auxiliary band 70 passes around a further front pulley 86 freely rotatable on front drive shaft 80 and around a further rear pulley 88 freely rotatable on shaft 82. Rear pulley 88 is of the same diameter as rear pulleys 78 of primary bands 72 while front pulley 86 of auxiliary band 70 is of a diameter slightly less than the diameters of front pulleys 76 of primary bands 72.

In the embodiment of Figures 4 to 7 certain other elements are shown in modified form but performing the same functions as those in the previous embodiment of Figures 1 to 3, thus spaced guide flanges 1 5 of a different configuration are adjustably mounted slidably on a crossbar 90 which also slidably carries retainer bar 50 mounted on an adjustable bracket 92. A pair of curved guide bars 94, mounted on a fixed crossbar 96, are located above platform 74 and laterally of primary bands 72. As in the previous embodiment friction wheel 32 is keyed on a journalled shaft 34 which is suspended from crossbar 96 by adjustable mounts 98 and driven by means not shown. Conventional exit belts 100 are located in front of friction wheel 32 and platform 74. Driven shaft 82 is adjustable by mounts 102 to vary the tension on bands 70 and 72.

In the operation of the embodiment of Figures 4 to 7 friction wheel 32 operates in the same manner as in the previous embodiment and guide bars 94 perform the same function as guide bar 20 by fanning the lowermost cards of stack 60 forwardly while the friction wheel allows the lowermost card 61 to move forward and restrains the cards immediately above it. As before, bottom card 61 is distorted arcuately from its normal plane (see Figure 6) which effects at least partial separation between the bottom card and the next lowermost card in the stack.

The invention provides an improved continuous feeding device for high speed operation. It is particularly advantageous in feeding thin sheets such as bank notes where adjacent notes tend to stick together. The importance of feeding such notes at high speed in accurately counted batches will be appreciated. Also, the invention inhibits smearing of ink on the sheet material because there is less pressure applied between the bands and the friction means.

In this respect the embodiment of Figures 4 to 7 affords a device in which auxiliary band 70 provides more frictional contact area beneath lowermost card 61 and assists in its separation from the next lowermost card in stack 60. The device of Figures 4 to 7 is useful for thinner cards in the range of .0035"-.005".

Paper, acetate or other sheet material may be fed by the method and device of this invention as long as it is flexible. There must be lateral clearance between the friction means and the bands of the conveyor platform to produce an arcuate or wavy contour in the sheet being fed between them which breaks the hold between that sheet and the next succeeding one in the stack. The lowermost surface of the friction means is usually located below the upper surface of the platform depending upon the gauge or thickness of the sheet material being fed through the device but in any event below the upper planar surface of the sheet material as it lies on the platform. Of course the number of bands or friction means may be increased as long as there are at least two bands and an interdisposed friction means or at least two friction means and an interdisposed band.

The friction means is preferably a friction wheel as described. Friction wheel 32 may rotate continuously or it may be governed to effect a pulsed rotation. A friction wheel approximately three-quarters of an inch in diameter has been found satisfactory for feeding most sheet material.

The purpose of a friction means is to retard the advancement of second card 62 while the purpose of rotation of the example embodiment is to prevent non-uniform wear of the friction surface which would adversely affect the efficiency of the feeding operation.

Claims (12)

1. A method of feeding flexible sheet material sequentially from a stack thereof, comprising the steps of: holding the stack of flexible sheets above a forwardly moving conveyor platform, the stack being held in a downwardly sloping position in the forward direction of travel of the platform and spaced therefrom, the lowermost sheets of the stack being fanned forwardly; retarding the forward movement of those sheets adjacent the lowermost sheet of the stack by friction means; allowing the single lowermost single sheet of stack to move forwardly on the platform between the platform and the friction means, and distorting said lowermost sheet arcuately from its normal plane by interaction between the friction means and the platform to effect at least partial lateral separation between said lowermost sheet and the adjacent next lowermost sheet.

2. A method as claimed in claim 1 in which the distortion of said lowermost sheet is effected by projecting the friction means below the upper planar surface of said sheet passing forwardly on the platform.

3. A method as claimed in claim 2 in which said lowermost sheet is supported upwardly beneath the friction means.

4. A method as claimed in claim 3 in which the conveyor comprises at least two laterally spaced endless bands and the friction means is positioned between the bands.

5. A method as claimed in claim 4 including an auxiliary endless band positioned between said two laterally spaced bands and beneath the friction means, the upper surface of the auxiliary band being lower than the planar upper surface of the platform formed by said two laterally spaced bands, the friction means being spaced from the auxiliary band to allow passage of a single sheet thereth rough.

6. A device for feeding flexible sheet material sequentially from a stack thereof, comprising: a conveyor providing a forwardly movable platform; means to hold the stack of flexible sheets above the platform in a downwardly sloping position in the forward direction of travel of the platform and spaced therefrom, said holding means including means whereby the lowermost sheets of the stack are fanned forwardly;; friction means positioned above the platform forwardly of the stack to retard the forward movement of those sheets adjacent the lowermost sheet of the stack, the friction means being spaced from the platform to allow passage of a single sheet therethrough and projecting below the upper planar surface of said single sheet whereby said upper planar surface is laterally distorted arcuately to effect at least partial lateral separation of said lowermost sheet from the adjacent next lowermost sheet; means to support the platform adjacent the friction means; and means to move the platform forwardly whereby said lowermost sheet is advanced towards said friction means.

7. A device as claimed in claim 6 in which the holding means comprises a forward guide bar and a rearward retainer bar each having a forwardly curving lower portion to fan the bottom sheets of the stack forwardly as the sheets move downwardly between the bars under the weight of the stack.

8. A device as claimed in claim 6 or 7 in which the friction means comprises arcuate means having the plane of arcuation vertically oriented with respect to the direction of movement of the platform.

9. A device as claimed in claim 8 in which the arcuate means comprises a wheel rotatable at the predetermined speed.

10. A device as claimed in any of claims 6 to 9 in which the means to support the platform comprises a roller.

11. A method of feeding flexible sheet material substantially as herein described.

12. A device for feeding flexible sheet material substantially as herein described with reference to and as shown in the accompanying drawings.