GB2309177A

GB2309177A - Paper shredder

Info

Publication number: GB2309177A
Application number: GB9700306A
Authority: GB
Inventors: Yet Chan
Original assignee: ACHIEVER Ltd
Current assignee: ACHIEVER Ltd
Priority date: 1996-01-22
Filing date: 1997-01-08
Publication date: 1997-07-23
Anticipated expiration: 2017-01-08
Also published as: GB2309177B; GB9700306D0; CN2267860Y

Description

PAPER SHREDDER The present invention relates to a paper shredder.

SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a paper shredder comprising a housing and a paper shredding mechanism provided inside the housing, which shredding mechanism comprises a cutting station formed by a rotatable shaft and a rotary cutter supported 6n the shaft for rotation by the shaft to cut paper fed through the cutting station, which cutter is protected by a stationary cover and has a part protruding out through the cover for paper cutting.

Preferably, the cutter is provided by a row of rotary cutting elements which are protected by a plurality of said covers.

More preferably, each of the cutting elements is protected by a pair of the covers on opposite sides.

It is preferred that the cutting elements and the covers are placed in an alternating manner on the shaft.

More preferably, the covers are placed against one another in a row, each of which is in angular engagement with an adjacent cover.

The cutter elements may preferably be in the form of cutting discs.

In a preferred embodiment, the cover has a surface extending outwards for guiding paper into the cutting station, through which surface the part of the cutter protrudes out for paper cutting.

In a preferred specific construction, the cutting station includes two said shafts and respective said cutters supported on the shafts to face each other for rotation by the respective shafts in opposite directions.

More preferably, each cutter is provided by a row of rotary cutting elements, and the two rows of cutting elements are axially staggered relative to each other.

It is preferred that the shredding mechanism includes an auxiliary cutting station formed by a rotatable helical cutting shaft provided behind the first-mentioned cutting station to further cut the paper fed through the firstmentioned cutting station.

According to a second aspect of the invention, there is provided a paper shredder comprising a housing and a paper shredding mechanism provided inside the housing, which shredding mechanism comprises a rotatable shaft and a plurality of rotary cutting elements supported on the shaft for simultaneous rotation by the shaft to cut paper fed through the cutting station, which cutting elements have substantially the same construction for use in combination to form a row of an adjustable length.

Preferably, the cutting elements are protected by stationary covers to have parts thereof exposed through the covers for paper cutting.

BRIEF DESCRIPTION OF DRAWINGS The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view of an embodiment of a paper shredder in accordance with the invention; Figure 2 is a top perspective view of an internal shredding mechanism of the paper shredder of Figure 1; Figure 3 is an exploded top perspective view of the shredding mechanism of Figure 2; and Figure 4 is a part of Figure 3, on an enlarged scale.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings, there is shown a paper shredder 10 embodying the invention, which shredder 10 has a housing 11 in the form of a cabinet having a horizontal top slot opening 12 and incorporates an internal shredding mechanism 13 behind the slot opening 12. Waste paper 9 is to be fed through the slot opening 12 into the housing 11 for cutting by the shredding mechanism 13 into small pieces which will then be collected in a waste bag provided inside the lower part of the housing 11. The shredding mechanism 13 has principal and auxiliary elongate cutting stations 14 and 15 which are mounted by a pair of mounting brackets 16 at opposite ends to the inside of housing 11 to extend lengthwise of the slot opening 12.In operation, the principal cutting station 14 takes in paper 9 and cuts it in the direction of travel into paper strips, with the auxiliary cutting station 15 immediately cutting the paper strips (while being formed) across into small paper pieces.

The principal cutting station 14 is provided by two rows 18A and 18B of cutting modules 19 supported on respective upper and lower horizonal shafts 17A and 17B to face each other. The shafts 17A and 17B have a hexagonal crosssection and are placed side-by-side close to each other to form a narrow gap 20 extending longitudinally between the two rows 18A and 18B of cutting modules 19. Each cutting module 19 has a generally flat ring-like body 21 including an integral strip portion 22 which extends substantially tangentially from the body 21 and has an outer surface 23.

The module body 21 has a circular central hole 24 which is co-axially enlarged on opposite sides to form a pair of cylindrical recesses 25. The recesses 25 have respective peripheral walls which are broken, through intersection with the surface 23 of the strip portion 22, to form a pair of aligned gaps 26 on opposite sides of the module body 21.

Each cutting module 19 includes a pair of cutting discs 27 and a washer spacer 28 sandwiched therebetween to form a rotary cutting unit 29. The cutting discs 27 have a diameter marginally smaller than that of the recesses 25 of the cutting module 19. The washer spacer 28 has a slightly smaller diameter than the cutting discs 27 in order to expose the cutting edges of the cutting discs 27. Each pair of adjacent cutting modules 19 on the same shaft 17A/17B are placed co-axially against each other and are angularly aligned by means of two side studs 21A provided on the interfacing side of one module body 21 engaging with respective side holes 213 formed on the interfacing side of the other module body 21.

At the interface, the pair of recesses 25 between the adjacent cutting modules 19 are aligned to form a flat cylindrical combined compartment for holding therein rotatably a said cutting unit 29. The gaps 26 of the pair of recesses 25 are also aligned to form a combined slot through which a small part 29A of the cutting unit 29 held inside the combined compartment is exposed to protrude slightly from the likewise aligned outer surfaces 23 of the strip portions 22 of the adjacent cutting modules 19, for paper cutting as hereinafter described. A collar spacer 30 is rotatably fitted co-axially within the central hole 24 of the body 21 of each of the adjacent cutting modules 19.

The collar spacers 30 on opposite sides of the cutting unit 29 between the adjacent cutting modules 19 serve to hold the cutting discs 27 and washer spacer 28 of the cutting unit 29 co-axially together.

In the assembled condition, the outer surfaces 23 of the strip portions 22 of the cutting modules 19 of the two rows 18A and 18B supported on the respective shafts 17A and 17B act as opposite sides of the gap 20 between the two cutting module rows 18A and 18B, extending outwards for guiding paper 9 into the gap 20. The cutting modules 19 of one row 18A/18B are axially shifted or staggered for half of the individual thickness of the module bodies 21 from those of the other row 18B/18A such that the protruding cutting part 29A of the cutting units 29 on opposite sides of the gap 20 are symmetrically offset from and are overlapped with each other when viewed in the longitudinal direction of the gap 20.

All the cutting discs 27 and the washer and collar spacers 28 and 30 have a hexagonal central hole 31 fitting onto the hexagonal cross-section of the shafts 17A and 17B in order to be rotated simultaneously by the associated shafts 17A and 17B. The shafts 17A and 17B are both rotatably supported at opposite ends by means of a pair of end-pieces 32 and associated bushings 33 and end-plates 34 on the respective mounting brackets 16. The end-pieces 32 are engaged with the module bodies 21 at the ends of the shafts 17A and 17B in order to hold the two rows 18A and 18B of the cutting modules 19 against rotation with the shafts 17A and 17B. The extreme ends of the shafts 17A and 17B exposed through the corresponding mounting brackets 16 are flattened so as to be rotated by a motor driving mechanism (not shown) which is generally known in the art.The shafts 17A and 17B are arranged to be driven in opposite directions to rotate, inter alia, the cutting units 29 of the cutting modules 19 on opposite sides with their cutting parts 29A down/into the gap 20 in order to cut paper 9 fed through the gap 20 in a direction front-to-back into paper strips.

The auxiliary cutting station 15 is provided by a helical cutting shaft 35 and a co-operating cutting blade 36. The cutting shaft 35 is rotatably supported at opposite ends by a pair of end-pieces 37 and associated bushings 38 on the aforesaid mounting brackets 16, at a position immediately behind the principal cutting station 14. The cutting blade 36 is fixed at opposite ends to the corresponding endpieces 37, at a position laterally against the cutting shaft 35. The interface between the cutting shaft 35 and the cutting blade 36 is aligned with the gap 20 of the principal cutting station 14. The extreme ends of the cutting shaft 35 are exposed through the respective mounting brackets 16 for rotation by the same aforesaid motor driving mechanism, simultaneously with the shafts 17A and 17B of the principal cutting station 14.

In operation, the cutting shaft 35 is rotated relative to and against the fixed cutting blade 36, in order to cut the paper strips produced by the principal cutting station 14, immediately when the paper strips are formed, laterally into paper pieces to complete the shredding operation.

Referring back to the principal cutting station 14, only small parts, namely the cutting parts 29A, of the cutting units 29 are exposed to be reached by and for cutting paper 9 to be shredded. As the rest of the cutting units 29 are fully covered or shielded and thus protected by the bodies 21 of the corresponding cutting modules 19, they will not be accessible by the paper 9. Consequently, the risk of paper jam is much reduced with the use of this shredding mechanism 13, compared with all the other paper shredding mechanisms known in the art.

It is important to note that the outer/rear side of the cutting units 29 need not necessarily be covered or protected because paper 9 to be shredded will not normally reach there.

Also, the use of the cutting elements, namely the cutting units 29, in a modular form having substantially the same construction, as in the case of the cutting modules 19 of the principal cutting station 14, greatly facilitates adjustment of the length of the cutting rows 18A and 18B which determines the maximum paper cutting width.

Accordingly, the production of shredding mechanisms in different maximum paper cutting lengths may share common parts, namely the cutting modules 19, thereby reducing the production costs.

In the principal cutting station 14, the cutting units 29 and the module bodies 21 on each shaft 17A/17B are placed co-axially in an alternating manner, with each cutting unit 29 protected by two adjacent module bodies 21 on opposite sides. It is envisaged that each cutting unit 29 may be enclosed by an individual cover or shell for independent protection.

In a different embodiment, only one of the shafts 17A/17B and associated cutting units 29 of the principal cutting station 14 is rotatable, with the other shaft 17B/17A and associated cutting units 29 being stationary, which may therefore have a simplified construction, as in the case of the fixed cutting blade 36 of the auxiliary cutting station 15.

The invention has been given by way of example only, and various modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims

WHAT IS CLAIMED IS

1. A paper shredder comprising a housing and a paper shredding mechanism provided inside the housing, which shredding mechanism comprises a cutting station formed by a rotatable shaft and a rotary cutter supported on the shaft for rotation by the shaft to cut paper fed through the cutting station, which cutter is protected by a stationary cover and has a part protruding out through the cover for paper cutting.

2. A paper shredder as claimed in claim 1, wherein the cutter is provided by a row of rotary cutting elements which are protected by a plurality of said covers.

3. A paper shredder as claimed in claim 2, wherein each of the cutting elements is protected by a pair of the covers on opposite sides.

4. A paper shredder as claimed in claim 3, wherein the cutting elements and the covers are placed in an alternating manner on the shaft.

5. A paper shredder as claimed in claim 4, wherein the covers are placed against one another in a row, each of which is in angular engagement with an adjacent cover.

6. A paper shredder as claimed in claim 2, wherein the cutter elements are in the form of cutting discs.

7. A paper shredder as claimed in claim 1, wherein the cover has a surface extending outwards for guiding paper into the cutting station, through which surface the part of the cutter protrudes out for paper cutting.

8. A paper shredder as claimed in claim 1, wherein the cutting station includes two said shafts and respective said cutters supported on the shafts to face each other for rotation by the respective shafts in opposite directions.

9. A paper shredder as claimed in claim 8, wherein each cutter is provided by a row of rotary cutting elements, and the two rows of cutting elements are axially staggered relative to each other.

10. A paper shredder as claimed in claim 1, wherein the shredding mechanism includes an auxiliary cutting station formed by a rotatable helical cutting shaft provided behind the first-mentioned cutting station to further cut the paper fed through the first-mentioned cutting station.

11. A paper shredder comprising a housing and a paper shredding mechanism provided inside the housing, which shredding mechanism comprises a rotatable shaft and a plurality of rotary cutting elements supported on the shaft for simultaneous rotation by the shaft to cut paper fed through the cutting station, which cutting elements have substantially the same construction for use in combination to form a row of an adjustable length.

12. A paper shredder as claimed in claim 11, wherein the cutting elements are protected by stationary covers to have parts thereof exposed through the covers for paper cutting.