SHEET FEEDING MECHANISM

Abstract: A sheet feeding mechanism for feeding sheets of documentary material such as paper into a chute, from which the sheet material will enter a shredding machine (10). The sheet feeding mechanism comprises a housing (12) within which there is mounted a pair of rollers (14a &cir& _, 14b &cir& _) around which a belt (16) of flexible material, such as rubber, is located, drive mechanism (10) being provided for rotating one of the rollers (14), to cause the belt to rotate within the housing (12). A central portion of the upper reach of the belt (16) passes over a support plate (18), to support the belt against movement in a downward direction. Between termination of the support plate (18) and passage of the belt on to the roller (14b &cir& _), the belt passes beneath a control member in the form of a plate (19), urged by a spring (30) into a position in which it is spaced a short distance (X) from the upper reach of the belt. A presser plate (26) is provided to urge a stack of paper on the upper stretch of the belt towards the belt. Such paper is gripped by movement of the belt and fed towards the gap (X), and between the roller (14b &cir& _) and a second roller (15) along a chute (11) into a shredding machine (40). In the event of the belt picking up a plurality of adjacent sheets, as these are fed towards the gap (X), the belt (16) will be deflected downwardly, passage of the increased thickness of paper beneath the control member (19) against the deflection of the belt (16) increasing the frictional forces acting between the belt and the lowermost sheet of paper.

Description: Title: Sheet feeding mechanism Description of Invention This invention is concerned with improvements relating to sheet feeding mechanism. Difficulty is encountered in feeding sheet material from a stack thereof, particularly where it is desired to fed more than one sheet at a time, and/or where it is desired that the mechanism used is simple in its construction and relatively inexpensive. For example in the feeding of documentary sheet material (such as paper) from a stack thereof to a shredding machine, the number of sheets which it may be desired to feed at a time will be dependent upon the capacity of the shredding machine being used. For example, single sheet feeding will lead to an under utilisation of the shredding machine, whilst if the number of sheets which are fed exceeds a certain value, the shredding machine will tend to jam. Difficulties are encountered in conventional feeding mechanisms for such operations, particularly in the ability of the sheet feeding mechanism to cope with a number of sheets which may be stapled together. According to this invention there is provided a sheet feeding mechanism comprising first and second spaced rollers, a flexible belt around the rollers, drive means to rotate the belt around the rollers, a support means to support an upper stretch of the belt as it moves from the first to the second roller, and a control member disposed above the upper stretch of the belt to provide with the belt a gap through which paper placed on the belt may be fed, the control member being disposed adjacent to a portion of the belt which is downwardly flexible. Preferably the belt is downwardly flexible to a specific extent, preferably downward flexibility being effected against a restraint of increasing force. Preferably the control member is disposed above a portion of the belt where the belt passes from the support means and prior to the belt passing onto the second roller. Thus, the capability of the belt being flexed downwardly will be by virtue of the inherent flexibility of the belt, in an unsupported region thereof. Preferably means is provided to vary the size of the gap. In this manner, by setting the gap at an optimum level, paper placed on the belt will be transferred through the gap, conveniently being fed to chute means for conveying the paper into a shredding machine, the size of the gap controlling the number of pages fed simultaneously by the sheet feeding mechanism. However in the event that a large number of pages, some of which may be stapled together, being fed through the gap, the belt will be flexed downwardly to increase the effective size of the gap, permitting passage through the gap of an increased number of pages. Increased forward force on the belt, as is necessary to cause the belt to flex in this manner, will increase the frictional forces between the belt and the lowermost sheet, increasing the force available for stripping the paper from (eg) a staple as may be causing the increased quantity. Preferably the control member is mounted for movement towards and away from the belt, preferably being urged (such as by a spring means) towards the belt into a position in which it is close to the belt, e.g. being spaced therefrom by a small distance. Thus in the event that a large number of sheets is feed into the gap, whilst initially the belt will be deflected downwardly to open the size of the gap as above described, when deflection of the belt reaches a maximum, the control member will be moved upwardly to further open the gap against the action of the spring, and such movement may be operative to cause control mechanism of the machine to switch off the machine and shredder. In this manner the feeding of an undesirably high number of sheets simultaneously into the shredder is obviated. Preferably clamping means is provided to urge a stack of paper downwardly against the belt, the belt picking up the lowermost sheet from such stack, and conveying it towards the gap, and towards the shredding machine. Preferably the clamping means comprises a member which is mounted for movement, so as to retain a disposition substantially parallel to the upper stretch of the belt, notwithstanding variation in the height of the stack of paper on the belt. Conveniently the clamping member is pivotally mounted, such as at a central region thereof, to a cover of the sheet feeding mechanism, which may be pulled down to enclose moving parts of the feeding mechanism, enabling safe operation thereof. Thus, conveniently the lid may be effective to operate an enabling switch, to cause or allow the drive means to operate. Conveniently the belt comprises a plurality of sections, spaced apart in the widthwise direction (i.e. at rights angles to the direction of travel). There will now be given a detailed description, to be read with reference to the accompanying drawings, of a sheet feeding mechanism which is the preferred embodiment of the invention, having been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings: FIGURE 1 is a schematic perspective view of the preferred embodiment; FIGURE 2 is a schematic longitudinal sectional view thereof; and FIGURE 3 is a more detailed perspective view of the preferred embodiment. The sheet feeding mechanism which is the preferred embodiment of the invention is specifically for the feer g of sheets of documentary material such as paper into a chute 11, from which me sheet material will enter a shredding machine 40, schematically shown in Figure 2, of conventional manufacture. The sheet feeding mechanism comprises a housing 12 within which there is mounted a pair of rollers 14a, 14^ around which a belt 16 of flexible material such as rubber or elastomer, is located. Drive mechanism 10 is provided for rotating one of the rollers 14, to cause the belt to rotate within the housing 16 in the direction shown. Spring means 42 may be provided to urge the rollers apart to maintain tension in the belt. The belt 16 comprises three sections 16a, 16b, 16c. spaced widthwise of the machine, a central portion of the upper reach of said sections passing over a support plate 18 carried by side plates of the housing 12 to support the belt against movement in a downward direction. Between the termination of the support plate 18 and the passage of the belt onto the roller 14b, the belt passes beneath a control member in the form of a plate 19, which is urged by a strong spring 30 acting between the plate 19 and a bar 31 extending from the housing on each side thereof, into engagement with a stop 32, so that the lower edge of the plate is spaced a short distance X from the upper reach of the belt, the stop 32 being adjustable to enable the distance X to be varied. Pivotally mounted on a shaft 20 towards the rear end of the machine is a cover 22, the cover carrying a presser plate 26 in a manner such that the presser plate is free for pivotal movement relative to the cover 22. As shown in Figures 1 and 2, the presser plate 26 may be carried on a pivotal mounting 24, but preferably, as is shown in Figure 3, the presser plate 26 carries spaced, parallel bars 36, which are receivable in slots 38 in the cover, springs being provided to urge the bars 36 into engagement with stops, allowing the presser plate 26 to float in either direction in a pivot-like upward movement against the action of the springs. In this manner the presser plate 26 may adopt a position in which it is substantially parallel to the upper reach of the belt 16, independent of the thickness of a stack of documentary material which may be placed with the machine. In the use of the machine, with the drive mechanism inoperative, a stack of documentary material will be placed within a receiving area 28, defined by the side walls of the housing, in engagement with the belt 16, and the lid 22 will be lowered allowing the presser plate 26 to rest on the documentary material. Such lowering of the lid may depress a micro-switch, causing a control circuit to be facilitated. In the operation of the machine, driving of the belt 16 will withdraw by frictional forces a sheet from the lowermost face of the stack, and convey the sheet through the gap X, to pass between the nip between the roller 14b and a further roller 15 into the chute 11 towards shredding mechanism 40, to be shredded. As successive sheets are fed, they are replaced, and in turn picked up by the belt for such feeding. In the event that a sheet picked up by the belt is stapled to a plurality of adjacent sheets, these will be fed towards the gap X, and a capability of the belt 16 to be deflected in the direction of the arrow Y (Figure 2), increases the size of the gap X. Passage of the increased thickness of documentary material beneath the control member 19 against the deflection of the belt 16 increases the frictional forces acting between the belt and the lowermost sheet of documentary material, increasing the force available for stripping such sheet, or adjacent sheets, as is necessary to enable an increased number to pass through the enlarged gap X. In the event that an unduly large number of sheets is stapled together, which are incapable of being stripped apart, subsequent to the achieval of maximum deflection of the belt, the control member 19 is free to lift to a small extent against the action of the springs 30, the force requiring to overcome the strong spring being greater than the force required initially to deflect the belt 16 in the direction Y. Such lifting of the control member 19 may be such as immediately to effect a termination operation, in which operation of the sheet feeding mechanism is terminated, together with (if desired) operation of the shredding mechanism, to prevent the shredding mechanism becoming jammed. Conveniently this is effected, as is shown in Figure 1, by the use of a control device 29 comprising an arm 42 projecting laterally from the plate 19 on its outer side, against which a spring loaded plunger 44 of a microswitch 46 is urged. As the control plate 19 rises to the maximum desired height, the permitted movement of the plunger 44 will open the microswitch 46, in turn causing the drive motor 10 to cease operation. In this manner the sheet feeding mechanism will operate automatically to feed paper at a fairly high rate but the machine will automatically terminate operation prior to a jam within the shredding machine occurring.

Claims: CLAIMS 1. A sheet feeding mechanism comprising first and second spaced rollers (14a, 14b) a flexible belt (16) around the rollers, drive means (10) to rotate the belt around the rollers, a support means (18) to support an upper stretch of the belt as it moves from the first (14a) to the second (14b) roller, and a control member (19) disposed above the upper stretch of the belt to provide with the belt a gap (X) through which paper placed on the belt may be fed, the control member (19) being disposed adjacent to a portion of the belt which is downwardly flexible. 2. A sheet feeding mechanism according to Claim 1 wherein said downward flexibility is effected against a restraint of increasing force. 3. A sheet feeding mechanism according to one of Claims 1 and 2 wherein the control member (19) is disposed above a portion of the belt (16) where the belt passes from the support means ( 18) and prior to the belt passing on to the second roller (14b). 4. A sheet feeding mechanism according to any one of the preceding claims wherein means is provided to vary the size of the gap (X). 5. A sheet feeding mechanism according to any one of the preceding claims wherein the control member (19) is mounted for movement towards and away from the belt (16), means (30) being provided to urge the control member (19) towards the belt into engagement with an adjustable stop. 6. A sheet feeding mechanism according to any one of the preceding claims comprising clamping means (22, 26) to urge a stack of paper downwardly against the belt. 7. A sheet feeding mechanism according to Claim 6 wherein the clamping means comprises a member (26) which is mounted for movement so as to retain a disposition substantially parallel to the upper stretch of the belt (16). 8. A sheet feeding mechanism according to one of Claims 6 and 7 wherein the clamping member (26) is mounted on a cover (22) of the sheet feeding mechanism. 9. A sheet feeding mechanism according to any one of the preceding claims wherein the belt (16) comprises a plurality of sections (16a, 16b, 16c) spaced apart in a widthwise direction. 10. A sheet feeding mechanism according to any one of the preceding claims comprising means (29) operative automatically to terminate operation of the feeding mechanism when the size of the gap is increased above a predetermined amount. 11. In combination, a sheet feeding mechanism according to any one of the preceding claims, and a shredding mechanism (40) arranged adjacent to the second roller (14b) such that paper fed by the mechanism is fed into the nip (N) of the shredder.

Inventors: BURLINGTON MICHAEL, WATKINS STEPHEN CHRISTOPHER, BURLINGTON, MICHAEL, WATKINS, STEPHEN, CHRISTOPHER
Applicants: ACCO REXEL GROUP SERVICES PLC, ACCO-REXEL GROUP SERVICES PLC
Application year: 1992
Main classification: B65H3
IPC codes: B65H3