EP1016461B1 - Cutting assembly for a document shredder - Google Patents

Description

The invention relates to a cutting device for document shredders, especially for office shredders.

For example, a document shredder is from the prior art known from DE 39 07 282 A1, at which a first bearing plate the mounting location for the flanged Electric motor, the roller bearings on the drive side the cutting rollers and one for a rolling bearing Reduction level is. To accommodate the second Rolling bearing of this reduction stage is a metal one additional bearing plate - in the form of a half-shell the first bearing plate mounted. To cover the gears following this reduction stage, is another half-shell-shaped bearing plate screwed the first bearing plate. This second half-shell shaped Bearing plate is for the sake of Soundproofing made from a (soft) plastic. The first bearing plate is very thick-walled because of it the rolling bearings essentially in their full width receives.

To reaction forces (possibly also torsional forces) the first bearing plate is to be attached via connecting struts with another - not shown there - Bearing plate connected. The two put on half-shell-shaped bearing plates do not wear to the rigidity of the entire gearbox, because they do not cover the entire area cover the first bearing plate and because the second half-shell Bearing plate also made of a plastic is.

Another is known from the document EP 0 010 681 A1 State of the art. Here is the transmission designed to be exchangeable for the exchange of cutting units. The drive unit includes the motor and a first one Gear stage; the pair of cutting rollers with his The cutting unit forms the second gear stage. The Gearbox with the engine is off, for example Made of plastic. Because of the divisibility and the associated assembly game and because part of the Gearbox is made of plastic, this gearbox construction do not absorb significant torsional forces. In addition, the separability can increase susceptibility to contamination.

Another, different gear design for one Document shredder can be seen in DE 40 03 222 C1. The case is vertical in an upper and in one lower plastic housing shell separable. In both Shells are each half holes for the admission of one Electric motor, gearbox and cutting roller bearings appropriate. A scraper is in one piece either on the upper or on the lower Molded shell. Because the housing shells only out Are plastic and have relatively large dimensions it can be caused by the reaction forces introduced considerable amounts of deformation on the overall housing come. The through the housing walking paper passage also reduces torsional rigidity.

Overall, it is disadvantageous that the cutting process torsional forces not directly at the point of origin - so in the gearbox area - intercepted become. This can lead to high loads and Wear in the bearings and on the gears come so it may even break the gear can come. Due to housing deformations it can on the cutting rollers because of their low cutting play also come to increased wear, so that they become dull prematurely.

DE 40 08 654 A1 is an office document shredder known, the two-part injection molded plastic housing has, the upper housing part as a cover that can be placed on the lower housing part is designed and the lower housing part mostly web-shaped wiper elements including the Cutting roller bearings in an integrated design includes. This results in all assembly friendliness however, the disadvantage that these devices are very restless run and are relatively loud because everyone is Drive and work noises as vibrations to the still as a reinforcing soundboard acting housing transferred.

So far, one has to solve this problem in technology tried by using massive bearing plates - partially even made of metal - for example like one Cutting device for document shredders according to US 5,163, 629, or by using very thick-walled plastic housing has used. All of these solutions are very complex and in the case the thick-walled plastic housing is dimensional accuracy often not possible because of thick-walled Plastic material leads to sink marks, which only partially compensated by long cycle times when spraying can be.

To continue the demands of the market at the time the applicant had a small document shredder according to DE 195 45 087 A1 (parallel US 5,893,524) developed. This small paper shredder consists of a bowl-like, the cutting rollers together with their front storage spaces and wiper elements containing lower housing part and mountable on it, with a material feed gap Provided upper housing part, in particular a Cutting unit with a gear housing and one drive motor arranged thereon as a structural unit below Interposition of damping elements in the aforementioned Lower housing part is stored. In another This shredder has a special construction still provided that the drive side Bearing plate for the cutting rollers also the one-piece Bottom of a bowl-like, through forms a lockable gear housing. What is disadvantageous about this constructive solution is that for the use of more powerful engines an increased Material use is necessary because of the wall thickness the gear housing must be enlarged.

It is therefore an object of the invention to provide a cutting mechanism to develop for shredders where the gear manufactured inexpensively and efficiently can be and also a high torsional rigidity has at the same time large Smoothness.

The task is accomplished by a cutter for shredders with the features of claim 1, 4 or 10 solved; the respective subordinate claims disclose extensions or exemplary embodiments the invention.

The inventor has found that specifically the reduction step with their camp reaction forces Introduces torsional moment into the housing. Further he found that a conventional gear cover does not contribute significantly to the rigidity.

That is why the registration item is now first of all the gearbox in the shape of a one Open side of the box, as straight as possible designed. The straightness prevents, for example the gearbox boundary walls buckling, also and especially when there are no stiffening ribs available.

Because a gearbox requires an assembly opening, it is now specifically provided here that the gear cover for this assembly opening, contrary to the closest prior art design according to the generic DE 195 45 087 A1, is a plate that is as free of curvature as possible; the same can additionally be connected to the open box part of the gear housing by means of a positive fit. These new details on a compact cutter for document shredders, the straightness of the gear boundary walls and the curvature-free plate essentially absorb the torsional thrust in the housing;
The positive effect of the connection of the plate with the box part of the gear housing is further enhanced.

This form fit is for example molded cams on the box - shaped housing and precisely fitting recesses in the plate. At least one fixing screw for the plate also ensures one, at least sufficient Frictional connection.

So this new unit, the invention, is made of an engine, Gearbox with a specially designed gearbox (including the reduction included therein), Cutting roller drive, cutting rollers, together with their Wiper elements, and the radial, rotatable coupling the cutting rollers at their other end, one functional, inexpensive to manufacture and also extremely torsion-resistant, compact unit, all here as a cutter for shredders referred to as.

An equivalent result for those in need of a solution Task is achieved in that instead of straightness the walls of the gearbox the relevant Wall, especially the drive side Wall, provided with a network of stiffening ribs is, with individual ribs of this rib network with the hubs of the wall provided on the drive side Bearing as well as with one or the side walls of the Gearbox are connected. It is advantageous that the stiffening ribs with their free top edge pointing inwards into the box-shaped housing part Face of the hubs of the bearings do not protrude their Height is preferably between 0.5 and 15 mm, advantageous at 10 mm.

In addition, an equivalent result for still achieves the task in need of solution that instead of the straightness of the walls the box-shaped housing part of the transmission housing, at least the wall in question, especially the drive side Wall, made of metal, preferably an injection molded part of the housing which is made in particular of a magnesium alloy consists. The advantages are that it is unlike Can not charge plastics electrically and therefore Cutting dust does not attract electrostatically, next to one high strength and low weight and the starting material for the alloy can be produced using environmentally friendly processes. For this reason, this material is also very good for scrapers, a 'mass article' on cutting units suitable for shredders.

By one or more of the above Basic variants of the invention are no longer that big Wall thickness required for the gearbox; moreover if provided, the height is also reduced the stiffening ribs to an economical level.

Another design detail of the invention is the elevation of the side walls, thus around the longitudinal axis around the gearbox, an approximately square one Cross section arises.

Another extension is that the plate is also also abutments for those located in the gearbox Can contain axes.

Another advantage of this new solution is the absolute Encapsulation of the gear housing so that no Dirt penetrate, but no lubricant escapes can.

When using the basic variant of the invention, the Providing stiffening ribs, there is an advantageous Design of the new box-shaped gear housing in its injection molding manufacture a plastic (preferably POM). Plastic POM has the advantage that, despite its lower density has good sliding and thus good storage properties.

Figur 1:

eine Gesamtansicht des erfindungsgemäßen Schneidwerkes für Aktenvernichter,

Figur 2:

ein offenes Kastenteil des Getriebegehäuses im Schnitt A-A und

Figur 3:

einen Blick in das offene Kastenteil des Getriebegehäuses mit Versteifungsrippen.

The invention will be explained in more detail in the constructional details with reference to an advantageous embodiment schematically shown in the drawings. Show it:

Figure 1:

an overall view of the cutting device according to the invention for document shredders,

Figure 2:

an open box part of the gearbox in section AA and

Figure 3:

a look into the open box part of the gearbox housing with stiffening ribs.

Figure 1 shows schematically a newly designed Cutting device 1 according to the invention, with a gear group and a pair of cutting rollers 9/12. The entire, compact cutter 1 is in this view removed from the bowl-like housing of the document shredder shown. A motor 2 is box-shaped Housing part 3 of a gear housing 5 attached. The box-shaped housing part 3 is with a curvature-free plate 4 which closed here forms the gear cover.

A pinion 6 of the motor 2 initially transmits the power on a reduction group 7 of the gear group. A gear 8 guides the drive power on to a cutting roller 9. In addition, a pinion guides 10 on the drive axis / shaft of the cutting roller 9 the driving force at the same time continues to a gear 11 a cutting roller 12. By this gear arrangement the cutting rollers 9 and 12 are opposed to each other. An abutment 13 takes the radial forces the ends of the cutting rollers facing away from the gear 5 9 and 12.

On the side of the Cutting rollers 9 and 12 is a comb-shaped Scraper 14 arranged. This, here only as an example indicated scraper, clears the grooves of the Cutting rollers 9 and 12.

2 shows the box-shaped housing part 3 presented very clearly. Its upper edge 15 is in essentially flat, so that, preferably rest without warping, plate 4 with a good seal can. The cams 16 molded onto the housing edge 15 allow a positive connection with the recesses the plate not shown here 4. A Stud 17a is used to hold a fastening screw for the plate 4. The dimension 18 gives the maximum height of the stiffening ribs on, this dimension 18 those facing inwards Front edges of the hubs 25, 26 and 27 of the bearings 22, 23 or 24 does not exceed.

The arrangement of stiffening ribs is shown in FIG 19 shown and their 19 connection with the hubs 25, 26 and 27 and the side walls of the box-shaped housing part 3. In addition, here is the placement of further stud bolts 17b and 17c for the optional attachment of the plate 4 see.

The invention is not based on the described embodiment limited, but within the scope of the revelation often variable. All mentioned in the above description as well even those that can only be extracted from the drawings Features are further components of the invention, even if not particularly highlighted and in particular are mentioned in the claims.

LIST OF REFERENCE NUMBERS

1

cutting

2

engine

3

box-shaped housing part

4

Plate (warp free)

5

gearbox

6

Pinion of the engine

7

reduction

8th

gear

9

cutting roller

10

pinion

11

gear

12

cutting roller

13

abutment

14

scraper

15

Top edge of item 3

16

cam

17a

studs

17b

studs

17c

studs

18

maximum height of the stiffening rib

19

stiffening ribs

20

transmission

21

longitudinal axis

22

camp

23

camp

24

camp

25, 26, 27

hub

Claims (15)

1. Cutting mechanism (1) for a document shredder, particularly an office document shredder, comprising cutting rollers together with their mounting plates at the end and stripper elements as well as a transmission together with a motor (2), which cutting mechanism (1) is arranged in a housing consisting of a shell-like housing lower part and a housing upper part placeable thereon and provided with a material feed gap, in which the bearing plate at the drive side for the cutting rollers (9, 12) at the same time forms the integral base of a similarly shell-like transmission housing (5) of the transmission, wherein the housing (5) is a box-shaped housing part (3) open on the side remote from the cutting rollers (9, 12) and closable by a transmission closure cover, characterised in that the transmission closure cover is a substantially planar and uncambered plate (4) and that at least the walls of the box-shaped housing part (3) are linearly planar.
2. Cutting mechanism (1) for a document shredder according to claim 1, characterised in that the uncambered plate (4) is connected in mechanically positive manner with the upper edge (15) of the open side of the box-shaped housing part (3).
3. Cutting mechanism (1) for a document shredder according to claim 1 or 2, characterised in that the uncambered plate (4) is a flat metal plate.
4. Cutting mechanism (1) for a document shredder, particularly an office document shredder, comprising cutting rollers together with their mounting plates at the end and stripper elements as well as a transmission together with a motor (2), which (1) is arranged in a housing consisting of a shell-like housing lower part and a housing upper part placeable thereon and provided with a material feed gap, in which the bearing plate at the drive side for the cutting rollers (9, 12) at the same time forms the integral base of a similarly shell-like transmission housing (5) of the transmission, wherein the housing (5) is a box-shaped housing part (3) open on the side remote from the cutting rollers (9, 12) and closable by a transmission closure cover, characterised in that at least one of the walls of the box-shaped housing-part (3) has stiffening ribs (19) arranged in reticular manner, wherein individual ribs (19) of this rib network are connected with one of or the side walls.
5. Cutting mechanism (1) for a document shredder according to claim 4, characterised in that the wall at the drive side of the box-shaped housing part (3), i.e. the integral base, has the said stiffening ribs (19).
6. Cutting mechanism (1) for a document shredder according to claim 5, characterised in that individual stiffening ribs (19) of the rib network are connected with hubs of the bearings provided in the wall at the drive side.
7. Cutting mechanism (1) for a document shredder according to claim 4, 5 or 6, characterised in that the stiffening ribs (19) have a height (18) which lies between 0.5 and 15 mm.
8. Cutting mechanism (1) for a document shredder according to claim 6, characterised in that the stiffening ribs (19) do not project by the free upper edge thereof beyond the end surface, which faces inwardly into the box-shaped housing part (3), of the hubs (25, 26, 27) of the bearings (22, 23, 24).
9. Cutting mechanism (1) for a document shredder according to claim 7 or 8, characterised in that the height of the stiffening ribs (19) amounts to 10 mm.
10. Cutting mechanism (1) for a document shredder, particularly an office document shredder, comprising at least the components or component groups of cutting rollers, associated stripper elements as well as bearing plates at the end, which cutting mechanism (1) is arranged in a housing consisting of a housing lower part and a housing upper part placeable thereon and provided with a material feed gap, wherein a transmission drivable by means of a motor is provided in or at the housing, characterised in that at least parts of the bearing plates at the end and/or the transmission housing consist at least partly of a magnesium alloy.
11. Cutting mechanism (1) for a document shredder according to claim 10, characterised in that the surfaces of the said parts are coated with a layer of a magnesium alloy.
12. Cutting mechanism (1) for a document shredder according to one of claims 1 and 11, characterised in that at least individual components or subassemblies of the cutting mechanism (1) consist at least partly of a high-grade synthetic material.
13. Cutting mechanism (1) for a document shredder according to claim 12, characterised in that the open box-shaped housing part (3) of the transmission housing (5) consists of a high-grade synthetic material.
14. Cutting mechanism (1) for a document shredder according to claim 12 or 13, characterised in that the said parts consist of a POM synthetic material.
15. Cutting mechanism (1) for a document shredder according to one of claims 4 to 14, characterised in that the said components or subassemblies of the cutting mechanism (1) are produced by injection-moulding.

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