WO2020249241A1

WO2020249241A1 - Shredder

Info

Publication number: WO2020249241A1
Application number: PCT/EP2019/065768
Authority: WO
Inventors: Willem Fredrik SMIT
Original assignee: M.E.F. Beheer B.V.
Priority date: 2019-06-14
Filing date: 2019-06-14
Publication date: 2020-12-17
Also published as: EP3983128C0; EP3983128B1; ES2950725T3; EP3983128A1

Abstract

The present invention relates to a shredder. More in particular, the present invention relates to a shredder configured for shredding confidential or sensitive data carriers, such as hard drives, and removable storage media such as USB or flash drives, floppy discs, data tapes and the like. The shredder according to the invention comprises a hollow rotatable guiding unit in which a first knife assembly is arranged. A sieve is disposed below the first knife assembly of which a size of the sieve openings decreases in the longitudinal direction of the guiding unit. According to the invention, the guiding unit is configured to collect pieces that are pushed through the openings of the sieve and to provide the collected pieces to the second side of the first knife assembly for subsequent cutting, punching, tearing or otherwise deforming. Furthermore, the guiding unit is configured to displace the collected pieces in the first direction between collecting the pieces and providing the pieces to the second side of the first knife assembly.

Description

Shredder

The present invention relates to a shredder. More in particular, the present invention relates to a shredder configured for shredding confidential and/or sensitive data carriers, such as hard drives, and removable storage media such as USB or flash drives, floppy discs, data tapes and the like. When shredding such devices, it is important to ensure that the maximum size of the shredded pieces is below a predefined limit. Such limit is set to prevent that useful data can be extracted from the shredded pieces.

A shredder for shredding confidential and/or sensitive data carriers is known from

WO201044658. In this device, a guillotine knife is used to cut the data carriers into very thin stripes.

As the data density, expressed as the number of bits per unit area, increases as technology develops, there exists a continuing need for reducing the maximum size of the shredded pieces.

The Applicant has found that it is difficult to meet the contemporary demands regarding the maximum size using the abovementioned shredder.

An object of the present invention is to provide a shredder that is able to shred data carriers to sufficiently small pieces.

This object is achieved by the shredder as defined in claim 1. According to the invention, the shredder comprises a guiding system including a hollow rotatable guiding unit elongated in a first direction from a first end toward an opposing second end. The guiding unit is configured to rotate about a rotational axis that is substantially parallel to the first direction. The shredder further comprises a first knife assembly arranged inside the guiding unit and comprising a plurality of first rotatable knifes that are adjacently arranged in the first direction. An elongated sieve extends in the first direction and is arranged spaced apart from the first knife assembly and faces a first side of the first knife assembly. A size of the openings of the sieve and/or a thickness of the first knifes decreases in the first direction In addition, the shredder comprises a drive system for driving the rotatable guiding unit and the plurality of first knifes.

According to the present invention, the first knife assembly is configured to cut, punch, tear or otherwise deform pieces to be shredded fed to a second side of the first knife assembly into smaller pieces, and to push the smaller pieces through the openings of the sieve. Furthermore, the guiding unit is configured to collect pieces that are pushed through the openings of the sieve and to provide the collected pieces to the second side of the first knife assembly for subsequent cutting, punching, tearing or otherwise deforming. The guiding unit is also configured to displace pieces that have been cut, punched, teared or otherwise deformed in the first direction before these pieces are provided to the second side of the first knife assembly for said subsequent cutting, punching, tearing or otherwise deforming. According to the invention, the pieces to be shredded are subjected to a sequence of cutting, punching, tearing or other deforming steps that take place on adjacent positions along the first direction. For example, the sieve can be divided into n segments, each segment being characterized by a respective size of the openings of the sieve. When pieces are cut, punched, teared or otherwise deformed by knifes of the first knife assembly that oppose a first segment among said n segments, they are pushed through the first segment of the sieve after which they are collected by the guiding unit. This latter unit then displaces the pieces along the first direction such that they are cut, punched, teared or otherwise deformed by knifes of the first knife assembly that oppose a second segment of the sieve among said n segments. The sieve openings of the second segment are smaller than the sieve openings of the first segment.

It should be noted that the present invention does not require that the sieve is positioned underneath each first knife. For example, a sieve may only be provided in the last sections of the first knife assembly. In such case, the first knifes may have a decreasing thickness in the first direction such that the first sections of the first knife assembly perform a shredding process without the resulting pieces being passed through a sieve. In any event, the pieces will be collected and transported by the guiding system.

The abovementioned shredding process of using decreasing sizes of sieve openings and/or decreasing thickness of first knifes in subsequent cutting, punching, tearing or other deforming steps that take place on separate and adjacent positions along the first direction allows shredding of confidential and/or sensitive data carriers into sufficiently small pieces.

The guiding unit may have the form of a hollow cylinder such as a drum. In such case, the first direction may correspond to the axis of the cylinder.

The guiding system may be configured to collect the pieces that have been cut, punched, teared or otherwise deformed in segments formed on an inside of the guiding unit and to transport the collected pieces in a circumferential direction relative to the rotational axis before allowing the collected pieces to fall onto the first knife assembly.

As a first example, the guiding unit can be configured to displace the pieces collected in the segments in the first direction before transporting them in said circumferential direction.

Typically, the pieces are transported while being held in the same segments as the segments in which they were collected. To allow the pieces to be displaced along the first direction, the guiding unit may be provided with a first wall connected to and extending from an inside of the guiding unit towards the first knife assembly, wherein the first wall spirals along the inside of the guiding unit from the first end toward the second end. The guiding unit may further comprise a second wall connected to and extending from the inside of the guiding unit along the first direction, wherein the first and second walls define the segments on the inside of the guiding unit. These segments preferably extend spirally along the inside of the guiding unit in the first direction. The first wall may be configured to displace the collected pieces in the first direction and the second wall may be configured to displace the collected pieces from the first side of the first knife assembly to the second side of the first knife assembly. The guiding may comprise a plurality of said second walls and/or a plurality of said first walls.

As a second example, the guiding system can be configured to displace the pieces that have been cut, punched, teared or otherwise deformed before collecting them in the segments. The guiding unit may be provided with a plurality of spaced apart third walls connected to and extending from the inside of the guiding unit along a circumferential direction, and one or more fourth walls connected to and extending from the inside of the guiding unit along the first direction. Here, the third and fourth walls define the segments on the inside of the guiding unit, wherein each segment is associated with a respective section of the first knife assembly. The guiding system may further comprise a plurality of displacement units, each displacement unit being associated with a respective section of the first knife assembly and being arranged in between the guiding unit and the sieve. The displacement units are further configured for displacing pieces that were provided to the second side of the first knife assembly from a first segment among said plurality of segments to a second segment among said plurality of segments, wherein the second segment is positioned further along the first direction than the first segment. Hence, after pieces have been cut, punched, teared, or otherwise deformed and before these pieces are provided to the second side of the first knife assembly for subsequent cutting, punching, tearing, or otherwise deforming, they are displaced in the first direction.

The first knife assembly may comprises a plurality of knife groups adjacently arranged in the first direction, wherein first knifes belonging to the same knife group have an identical thickness, and wherein a thickness of the first knifes decreases between knife groups in the first direction. The elongated sieve may comprise a plurality of sieve groups adjacently arranged in the first direction, wherein sieve openings belonging to the same sieve group have an identical size, and wherein a size of the sieve openings decreases between sieve groups in the first direction. Each sieve group may correspond to a respective knife group. In other words, the number of sieve groups can be equal to or less than the number of knife groups. Each knife group may correspond to a respective sieve group. In other words, the number of knife groups can be equal to or less than the number of sieve groups. In an embodiment, the number of knife groups is identical to the number of sieve groups.

The shredder may further comprise a fall guiding unit for guiding a fall of the pieces from the inside of the guiding unit to the second side of the first knife assembly. The exact moment in time at which a piece will fall from the inside of the guiding unit down towards the first knife assembly may differ as the weight, shape, and size of the pieces may differ. To ensure that all pieces arrive in a well defined area, a fall guiding unit can be used. Such fall guiding unit may for example comprise two plates that are elongated in the first direction and that are positioned in an inclined manner relative to a vertical direction to form a funnel that tapers towards the first knife assembly.

The first knife assembly may comprise a first rotatable shaft extending in the first direction and on which the first knifes are mounted. The first knife assembly may further comprise a second shaft arranged parallel to the first shaft and on which first counter elements are arranged. Each first knife is configured to cooperate with a respective first counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded.

The first counter elements may each comprise a respective second knife. Each first knife, and the respective second knife it is configured to cooperate with, can be shaped identically.

Additionally or alternatively, the first and/or second knifes may each comprise a disc mounted to the first shaft or second shaft, respectively, each disc comprising an alternating arrangement in the circumferential direction of the disc of protruding portions and recessed portions. In this manner, cutting edges are formed at the interfaces between the protruding portions and recessed portions.

At a time of cutting, punching, tearing or otherwise deforming the pieces to be shredded, the protruding portions of the first knifes can be opposing the protruding portions of the second knifes. More preferably, the actual cutting, punching, tearing or otherwise deforming the pieces to be shredded continuously comprises similar portions of the first and second knifes working together. Put differently, the angular position of the disc can be described by referring to a particular protruding portion. For example, a disc may comprise 6 protruding portions and 6 recessed portions. In this case, the angular start position of each protruding portion can be expressed as -15, 45, 105, 165, 225, and 285 degrees and the angular start position of each recessed portion as 15, 75, 135, 195, and 255 degrees. The angular position of the disc relative to a fixed reference point, such as the central axis of the first or second shaft, can be expressed in a similar manner. For example, an angular position of 0 degrees may correspond to an angular position of the disc in which a center of the first protruding portion is aligned with the vertical direction.

According to the invention, the angular positions of the discs of the first knifes are identical and the angular positions of the discs of the second knifes are identical. Additionally or alternatively, the second and first knifes can be configured such that at a given moment in time, the angular positions of the discs of these knifes is identical, e.g. 0 degrees. Thereafter, the first knifes may be configured to rotate clockwise or counter-clockwise whereas the second knifes may be configured to rotate counter-clockwise or clockwise, respectively.

A distance between each protruding portion of the first and/or second knifes and the sieve, at a time when the protruding portion is facing a sieve opening, may be less than a size of that opening. In this manner, accumulation of pieces in between the sieve and knifes is prevented. If pieces cannot pass through the sieve openings, they will be transported in the recessed portion from the first side of the knife assembly to the second side of the knife assembly.

The second shaft may be rotatable. In this case, a rotational movement of the first shaft can be mechanically coupled to a rotational movement of the second shaft, wherein the first knife assembly preferably comprises a first gear connected to the first shaft, said first gear engaging a second gear that is connected to the second shaft. In this manner, the first and second shafts are configured to rotate clockwise and counter clockwise, respectively, or vice versa. Furthermore, the drive system may comprise a first motor, preferably an electrical motor, for rotating the guiding unit and one of the first shaft and the second shaft. It may be advantageous if the drive system further comprises a gear transmission to allow said one of the first shaft and the second shaft and the guiding unit to rotate at different speeds. For example, the guiding unit should rotate at such a speed that the collected pieces fall onto the first and/or second knifes at a second side of the first knife assembly. If the guiding unit rotates too slowly, pieces may fall next to the knife assemblies. If the guiding unit rotates too quickly, pieces may remain stuck against an inside of the guiding unit due to centrifugal forces.

Alternatively, the drive system may comprise a first motor, preferably an electrical motor, for rotating the guiding unit and a second motor, preferably an electrical motor, for rotating one of the first shaft and the second shaft.

The shredder may further comprise a collecting unit arranged near the second end of the guiding unit, wherein the collecting unit is configured to collect pieces that have been pushed through a last segment of the sieve. This last segment is characterized in that the openings of the sieve in this segment are the smallest among the openings of the sieve. Hence, when pieces are pushed through these openings no further shredding is needed. The collecting unit allows these pieces to be removed from the guiding unit for subsequent processing or storage.

The shredder may also comprise a feeding unit for feeding pieces to be shredded to one of the guiding unit and the second side of the first knife assembly near the first end. Consequently, the pieces to be shredded can be cut directly or can first be transported using the guiding unit. This feeding unit may be arranged outside of the guiding unit. Furthermore, the feeding unit may comprise a second knife assembly comprising a plurality of rotatable third knifes that are adjacently arranged in the first direction, and a further guiding unit spaced apart from the second knife assembly and configured to guide pieces that have been cut by the third knifes towards the guiding unit. This second knife assembly may comprise a rotatable third shaft extending in the first direction on which the third knifes are mounted, and a fourth shaft parallel to the third shaft and on which second counter elements can be arranged. Each third knife can be configured to cooperate with a respective second counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded. The third shaft may be driven by the drive system using the motor(s) that are used to drive the guiding unit and the first knife assembly or by a separate motor.

The shredder may further comprise fourth knifes mounted to the fourth shaft, and third counter elements mounted to the third shaft, wherein each fourth knife is configured to cooperate with a respective third counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded, wherein the third knifes and the third counter elements are alternately arranged on the third shaft, and wherein the fourth knifes and the second counter elements are alternately arranged on the fourth shaft. Additionally or alternatively, the third and/or fourth knifes may each comprise a disc mounted to the third shaft or fourth shaft, respectively, and comprise an alternating arrangement in the circumferential direction of protruding portions and recessed portions. The mounting of the discs of the third and fourth knifes is such that protruding portions of adjacently arranged third knifes and/or the protruding portions of adjacently arranged fourth knifes are arranged with an angular offset relative to each other. Hence, whereas the first and second knifes of the first knife assembly may have the same angular positions of the discs, it is preferred to introduce an offset in the angular position between adjacent third or fourth knifes.

The third and fourth counter elements may each comprise a disc preferably having a smooth edge and mounted to the third shaft or fourth shaft, respectively.

The first and third shafts and the second and fourth shafts may be integrally connected.

Next, the invention will be described in more detail referring to the appended drawings, wherein:

Figure 1 illustrates an embodiment of a shredder according to the invention;

Figure 2 illustrates the embodiment of figure 2 from a different perspective;

Figure 3 illustrates a perspective partially opened view of the shredder of figure 1 ;

Figure 4 illustrates a cross section of the shredder of figure 1 ;

Figure 5 illustrates the general concept of the invention;

Figure 6 illustrates a cross section at the position of the feeding unit of the shredder of figure 1;

Figure 7 illustrates a cross section at the position of the guiding unit of the shredder of figure 1;

Figure 8 schematically illustrates a path of a piece to be shredded inside the guiding unit of a shredder in accordance with the present invention; and

Figure 9 presents an alternative arrangement of a shredder according of the invention.

Now referring to figure 1, an embodiment of a shredder 100 according to the invention comprises a first frame part 101 that can be arranged on a floor and a second frame part 102 in which the moving part of shredder 100 to be discussed next are mounted. Second frame part 102 comprises two spaced apart plates 103 that are mutually connected using bars 104. Bars 104 are connected to guiding rollers 105 that rotatably support a guiding unit in the form of a hollow drum 110. Drum 110 is elongated in a first direction thereof, which, in figure 1, corresponds to the longitudinal direction of bars 104 from left to right.

Drum 110 can be rotated by a drive system 140 comprising an electric motor 141. A drive shaft 145 of this motor is connected via a belt (not shown) to a roller shaft 146 that is connected to a guiding roller 105. This is depicted in more detail in figure 3. It should be noted that guiding rollers 105 are provided in pairs, wherein one guiding roller 105 is actively driven by electric motor 141.

Referring back to figure 2, drive shaft 145 is further connected via a gear (not shown) and a transmission chain (not shown) to transmission gear 144. This latter gear, as well as gear 142, is mounted to a first shaft 123. Gear 142 is coupled to a gear 143 that is mounted to a second shaft 124. When transmission gear 144 is driven, first shaft 123 and second shaft 124 will rotate in opposite directions.

Now referring to figure 3, in which drum 110 is only visible in outline, shredder 100 comprises a first knife assembly 120 arranged inside drum 110, and a second knife assembly 150 arranged outside drum 110. Cross sections of first knife assembly 120 and second knife assembly 150 are shown in figures 7 and 6, respectively.

Now referring to figures 3 and 7, first knife assembly 120 comprises a plurality of first knifes 121 and second knifes 122 that are adjacently arranged in the first direction. First knifes 121 are mounted to first shaft 123 and second knifes 122 to second shaft 124. To this end, plates 103 comprise suitable bearings 106.

At a first side of first knife assembly 120 and at a distance therefrom a sieve 130 is arranged that comprises a plurality of sieve openings 131, see figure 4. As can be observed from the cross section shown in figure 4 the size of the sieve openings decreases along the first direction. More in particular, sieve 130 can be divided into segments 130_1-130_4, each segment having a different size of sieve openings 131_1-131_4.

Each first knife 121 and each second knife 122 comprise a disc 125 having protruding portions 126 and recessed portions 127. At an interface between portions 126, 127, a cutting edge 128 is formed. In the embodiment shown in the figures, first knifes 121 are identical to each other and identical to second knifes 122. Moreover, as shown in figures 3 and 4, each first knife 121 is mounted to first shaft 123 in a similar manner in the sense that all portions 126, 127 of all first knifes 121 align with each other in the first direction. Similarly, each second knife 122 is mounted to second shaft 124 in a similar manner in the sense that all portions 126, 127 of all second knifes 122 align with each other in the first direction. When a piece 200 to be shredded is positioned in between a first knife 121 and a second knife 122 it will be cut, punched, teared or otherwise deformed. Thereafter, it will either pass through a sieve opening 131 or it will be transported inside a recessed portion 127 from the bottom side, i.e. the first side, of first knife assembly 120 to a top side, i.e. the second side, thereof where it may be processed again. Here, it is noted that first knifes 121 and second knifes 122 are positioned relatively close to sieve 130, for example at a distance not exceeding 2 mm. This prevents the accumulation of debris between knifes 121, 122 and sieve 130.

It should be noted that first knifes 121 and second knifes 122 can be divided into knife groups. In each knife group, the thickness of the knifes in that group is identical. However, the thickness of the knifes among different groups may vary. Similarly, the sieve may be divided into sieve groups, wherein a size of the sieve openings in a sieve group is constant whereas it varies among different sieve groups. As an example four sieve groups and four knife groups can be used wherein, in the first direction, the size of the sieve opening and the thickness of the knifes of the respective groups are, in mm, (9, 8), (7, 8), (5, 6), and (3.5, 6), respectively. For example, the third knife group comprises first and second knifes that have a thickness measured along the first direction, e.g. the thickness of the relevant discs, equal to 6 mm, whereas the size of the sieve openings of the third sieve group equals 5 mm. In other embodiments, the thickness of the knifes remains constant throughout the entire first knife assembly, but the sieve openings will decrease in size along the first direction.

Now referring to figures 3 and 6, second knife assembly 150 comprises a plurality of third knifes 151 mounted to first shaft 123 and a plurality of fourth knifes 152 mounted to second shaft 124. Similar to first knifes 121, third knifes 151 each comprise a disc 155 having protruding portions 156 and recessed portions 157. A cutting edge 158 is formed at the interface between portions 156, 157.

Contrary to first knife assembly 120, third knifes 151 and fourth knifes 152 do not cooperate with each other for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded. Instead, third knifes 151 cooperate with second counter elements 153 that are attached to second shaft 124. Similarly, fourth knifes 152 cooperate with third counter elements 154 that are attached to first shaft 123. More in particular, third knifes 151 and third counter elements 154 are alternately arranged on first shaft 123 and fourth knifes 152 and second counter elements 153 are alternately arranged on second shaft 124. Moreover, in the embodiment shown, there is no sieve arranged below second knife assembly 150. In addition, filling plates 159, which are fixedly arranged, are provided to partially surround counter elements 153, 154 to prevent debris from stacking up in between knifes 151, 152.

Now referring to figures 1 and 6, a feeding funnel 160 is provided in which a user may insert pieces 200 to be shredded. Feeding funnel 160 will guide these pieces towards second knife assembly 150. On the opposite side of second knife assembly 150 a guiding plate 161 is provided that guides the pieces that have been processed by second knife assembly 150 onto the inside wall of drum 110.

Now referring to figures 3, 4, and 7, an inside wall of drum 110 comprises one or more spiral walls 111 (only one shown for illustrative purposes) that extends in the first direction in a spiraled manner. The inside wall of drum 110 further comprises longitudinal walls 112 that extends in the first direction. Spiral wall 111 induces a displacement of pieces that have been processed by first knife assembly 120 in the first direction. Longitudinal walls 112 induce a rotational movement of these pieces to subject them to a subsequent processing by first knife assembly 120.

It should be noted that spiral wall 111 is shown schematically. The actual design thereof, i.e. the number of spiral walls and the number of turns per unit length should be designed such that pieces are displaced in the first direction sufficiently far such that when they fall downward they will be collected in a segment that is positioned more downstream along the first direction.

When a piece to be shredded is inserted into feeding funnel 160 it will be subjected to an initial processing by second knife assembly 150 as a result of which a first shredding action is provided. Thereafter, the pieces will be provided to the inside wall of drum 110. There, the pieces will be engaged by spiral wall 111 that will displace the pieces in the first direction while the pieces essentially remain positioned near a bottom of drum 110. At a given moment, the pieces will be engaged by longitudinal wall 112 which will push the pieces in the circumferential direction. When the pieces have obtained a given angular position they will fall downward onto first knife assembly 120 albeit at a position along the first direction different from the position at which they were fed to drum 110 by guiding plate 161. At this position, the pieces will be subjected to a cutting, punching, tearing or other deforming action performed by first knife assembly 120.

Thereafter, if the pieces are smaller than sieve openings 131 _ 1, they will pass through sieve openings 131 _ 1 and fall onto the inside wall of drum 110. There, the sequence of displacement in the first direction and subsequent displacement in the circumferential direction will be repeated. This will cause the pieces to subsequently fall onto first knife assembly 120 at an even further position along the first direction. The pieces will be subjected to a sieving action using a decreasing size of the sieve openings 131. Consequently, when viewed along the first direction, the sizes of pieces 200 will decrease. This is illustrated in figure 5.

In figure 4, four discrete segments of sieve 130 are shown that each have a single size of sieve opening 131. In other embodiments, a size of sieve openings 131 will be constant in the circumferential direction but the size will gradually decrease in the first direction.

Furthermore, to better control the position of pieces 200 to be shredded, a funnel shaped fall guiding unit is provided that comprises opposing walls 162A, 162B. As shown in figure 4, at a downstream end of drum 110, a collecting unit 170 is provided in the form of a guiding plate. This plate will transport pieces that have been processed by an end part of first knife assembly 120 to outside drum 110 where they may be collected in a container.

Figure 8 illustrates the concept of the present invention for an embodiment of a shredder of which the inside wall comprises two longitudinal walls 11 2_1, 112_2, and two spiral walls 111 _ 1,

111_2. Figure 8, the bottom section, illustrates a segment of the inside wall of the drum if it were cut along a straight line in the first direction and if the inside wall were laid flat. In figure 8, such cut is made through longitudinal wall 112_1. Accordingly, to again form a drum, the top side of the inside wall shown in figure 8 has to be connected to the bottom side. Furthermore, the top section of figure 8 illustrates a cross section of drum 110 perpendicular to the first direction.

In figure 8, bottom section, the vertical axis corresponds to the angular position f in degrees and the horizontal axis to the displacement x of piece 200 in the first direction of piece. Furthermore, figure 8, bottom section, illustrates a starting position at a time t=0 of the inside wall of the drum.

In figure 8, bottom section, a plurality of segments sl_l - sl_5 and s2_l - s2_5 can be identified. To explain how a piece to be shredded is transported in the shredder, it is assumed that a piece 200 is located in segment 1_2 in the bottom left corner at t=0. This position is indicated as pi. As the drum rotates as indicated by arrow M, i.e. counter clockwise, spiral wall 111_2 will push against piece 200 thereby displacing it to the right towards position p2. At this position, piece 200 will be engaged by longitudinal wall 112_2, which at that time has moved to an angular position of 0 degrees. Thereafter, the position of piece 200 in the first direction will not change as piece 200 will only change its circumferential position. More in particular, the angular position of piece 200 will change from 0 degrees towards -180 degrees. However, to be able to represent the position of piece 200 at several stages, this position is indicated at 180 degrees in figure 8, i.e. as position p3.

It is assumed that at position p3, corresponding roughly to the top position shown in the cross sectional view in the top section of figure 8, piece 200 will fall downward to position p4. More in particular, piece 200 will fall from segment sl_2 into segment s2_3. Thereafter, piece 200 will be engaged by spiral wall 111_1 pushing piece 200 from position p4 to position p5. There, it will be engaged by longitudinal wall 112_2 bringing piece 200 to position p6. At this position, piece 200 will fall from segment s2_3 into segment sl_4 to arrive at position p7. Thereafter, piece 200 will be engaged by spiral wall 111_2 pushing piece 200 from position p7 to position p8. There, it will be engaged by longitudinal wall 111_2 bringing piece 200 to position p9. At this position, piece 200 will fall from segment sl_4 into segment s2_5 to arrive at position plO.

In the description above, it was assumed that a size of piece 200 was reduced by first knife assembly in such a manner that piece 200 fitted through the corresponding sieve openings each time after it was processed by the knifers of the first knife assembly at the location corresponding to position x in the first direction.

The present invention does not exclude a different number of longitudinal and/or spiral walls to be used. However, in a preferred embodiment, a plurality of longitudinal walls and/or a plurality of spiral walls is used. By using one or more longitudinal walls and one or more spiral walls, the inside of the drum is divided into segments. Each segment covers a particular positional range, e.g. between 30 cm and 40 cm in the first direction. The design of the inside wall should be such that when a piece falls onto the first knife assembly and passes through the sieve openings it will be captured in a second segment other than the first segment in which it was carried to the top side of the drum. Moreover, the second segment should cover a positional range that is further along the first direction than the positional range of the first segment.

Figure 9 illustrates a different approach of a guiding unit configured to displace pieces that have been cut, punched, teared or otherwise deformed in the first direction before these pieces are provided to the second side of the first knife assembly for subsequent cutting, punching, tearing or otherwise deforming.

In figure 9, first knife assembly 220 comprises a plurality of segments 221 arranged in the first direction. Similar to the previous embodiment, a sieve 230 is arranged below first knife assembly 220. Sieve 230 can also be divided into segments 231 , each segment corresponding to a respective segment of first knife assembly 230, and wherein a size of the openings of sieve 230 decreases in the first direction. Preferably, the size of the openings of sieve 230 is constant within a segment 231 but differ among segments 231.

Inside wall 211 of drum 210 can also be divided into segments 212 that are formed using walls 213 that extend in the circumferential direction only. As shown, segments 212 correspond to segments 221 and segments 231.

For each segment 231 , a guiding plate 240 is arranged that displaces the pieces that have passed through sieve 230 to an adjacent segment 212 on inside wall 211 of drum 210.

Consequently, pieces to be shredded are displaced in the first direction between the moment of cutting, punching, tearing or otherwise deforming the pieces and the moment of providing the pieces to the second side of the first knife assembly for subsequent cutting, punching, tearing or otherwise deforming the pieces.

In the above, the present invention has been described using detailed embodiments thereof. However, the present invention is not limited by these embodiments. More in particular, one or more modifications can be made to the embodiments without departing from the scope of the invention which is defined by the appended claims. List of reference signs shredder 100

first frame part 101

second frame part 102

plate 103

bar 104

guiding roller 105

bearing 106

drum 110

spiral wall 111

longitudinal wall 112, 112_1, 112_2

first knife assembly 120

first knife 121

second knife 122

first shaft 123

second shaft 124

disc 125

protruding portion 126

recessed portion 127

cutting edge 128

sieve 130

sieve opening 131, 131 _ 1, 131 _ 2, 131_3, 131_4 drive system 140

electric motor 141

gear first shaft 142

gear second shaft 143

transmission gear 144

drive shaft 145

roller shaft 146

second knife assembly 150

third knife 151

fourth knife 152

second counter element 153

third counter element 154

disc 155 protruding portion 156 recessed portion 157 cutting edge 158 filling plate 159 feeding funnel 160 guiding plate 161 wall fall guiding unit 162A, 162B collecting unit 170 drum 210 inside wall drum 211 segment inside wall drum 212 wall 213 first knife assembly 220 segment first knife assembly 221 sieve 230 segment sieve 231 guiding plate 240

Claims

1. A shredder, comprising:

a guiding system including a hollow rotatable guiding unit elongated in a first direction from a first end toward an opposing second end, said guiding unit being configured to rotate about a rotational axis that is substantially parallel to the first direction;

a first knife assembly arranged inside the guiding unit and comprising a plurality of first rotatable knifes that are adjacently arranged in the first direction;

an elongated sieve extending in the first direction and arranged spaced apart from the first knife assembly and facing a first side of the first knife assembly; and

a drive system for driving the rotatable guiding unit and the plurality of first knifes;

wherein the first knife assembly is configured to cut, punch, tear or otherwise deform pieces to be shredded fed to a second side of the first knife assembly into smaller pieces, and to push the smaller pieces through openings of the sieve;

wherein the guiding unit is configured to collect pieces that are pushed through the openings of the sieve and to provide the collected pieces to the second side of the first knife assembly for subsequent cutting, punching, tearing or otherwise deforming;

wherein the guiding system is configured to displace pieces that have been cut, punched, teared or otherwise deformed in the first direction before these pieces are provided to the second side of the first knife assembly for said subsequent cutting, punching, tearing or otherwise deforming; and

wherein a size of the openings of the sieve and/or a thickness of the first knifes decreases in the first direction.

2. The shredder according to claim 1 , wherein the guiding system is configured to collect the pieces that have been cut, punched, teared or otherwise deformed in segments formed on an inside of the guiding unit and to transport the collected pieces in a circumferential direction relative to the rotational axis before allowing the collected pieces to fall onto the first knife assembly.

3. The shredder according to claim 2, wherein the guiding unit is configured to displace the pieces collected in the segments in the first direction before transporting them in said circumferential direction.

4. The shredder according to claim 2 or 3, wherein the guiding unit is provided with: a first wall connected to and extending from an inside of the guiding unit towards the first knife assembly, wherein the first wall spirals along the inside of the guiding unit from the first end toward the second end; and

a second wall connected to and extending from the inside of the guiding unit along the first direction, wherein the first and second walls define said segments on the inside of the guiding unit.

5. The shredder according to claim 4, wherein the first wall is configured to displace the collected pieces in the first direction and wherein the second wall is configured to displace the collected pieces from the first side of the first knife assembly to the second side of the first knife assembly.

6. The shredder according to claim 4 or 5, wherein the guiding unit comprises a plurality of said second walls and/or comprising a plurality of said first walls.

7. The shredder according to claim 2, wherein the guiding system is configured to displace the pieces that have been cut, punched, teared or otherwise deformed before collecting them in the segments.

8. The shredder according to claim 7, wherein the guiding unit is provided with: a plurality of spaced apart third walls connected to and extending from the inside of the guiding unit along a circumferential direction, and

one or more fourth walls connected to and extending from the inside of the guiding unit along the first direction, wherein the third and fourth walls define said segments on the inside of the guiding unit, each segment being associated with a respective section of the first knife assembly;

wherein the guiding system is provided with a plurality of displacement units, each displacement unit being associated with a respective section of the first knife assembly and being arranged in between the guiding unit and the sieve, and being configured for displacing pieces that were provided to the second side of the first knife assembly from a first segment among said plurality of segments to a second segment among said plurality of segments, wherein the second segment is positioned further along the first direction than the first segment.

9. The shredder according to any of the previous claims, wherein the first knife assembly comprises a plurality of knife groups adjacently arranged in the first direction, wherein first knifes belonging to the same knife group have an identical thickness, and wherein a thickness of the first knifes decreases between knife groups in the first direction.

10. The shredder according to claim 9, wherein the elongated sieve comprises a plurality of sieve groups adjacently arranged in the first direction, wherein sieve openings belonging to the same sieve group have an identical size, and wherein a size of the sieve openings decreases between sieve groups in the first direction.

11. The shredder according to claims 9 and 10, wherein each sieve group corresponds to a respective knife group.

12. The shredder according to claims 9, 10, and 11 , wherein each knife group corresponds to a respective sieve group.

13. The shredder according to any of the previous claims, further comprising a fall guiding unit for guiding a fall of the pieces from the inside of the guiding unit to the second side of the first knife assembly.

14. The shredder according to any of the previous claims, wherein the first knife assembly comprises:

a rotatable first shaft extending in the first direction and on which the first knifes are mounted; and

a second shaft arranged parallel to the first shaft and on which first counter elements are arranged;

wherein each first knife is configured to cooperate with a respective first counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded.

15. The shredder according to claim 14, wherein the first counter elements each comprise a respective second knife.

16. The shredder according to claim 15, wherein each first knife, and the respective second knife it is configured to cooperate with, are shaped identically.

17. The shredder according to claim 14, 15 or 16, wherein the first and/or second knifes each comprise a disc mounted to the first shaft or second shaft, respectively, each disc comprising an alternating arrangement in the circumferential direction of the disc of protruding portions and recessed portions.

18. The shredder according to claims 16 and 17, wherein, at a time of cutting the pieces to be shredded, the protruding portions of the first knifes are opposing the protruding portions of the second knifes.

19. The shredder according to claim 17 or 18, wherein a distance between each protruding portion of the first and/or second knifes and the sieve, at a time when the protruding portion is facing a sieve opening, is less than a size of that opening.

20. The shredder according to any of the claims 15-19, wherein the second shaft is rotatable and wherein a rotational movement of the first shaft is mechanically coupled to a rotational movement of the second shaft, wherein the first knife assembly preferably comprises a first gear connected to the first shaft, said first gear engaging a second gear that is connected to the second shaft.

21. The shredder according to claim 20, wherein the drive system comprises a first motor, preferably an electrical motor, for rotating the guiding unit and one of the first shaft and the second shaft.

22. The shredder according to claim 21, wherein the drive system further comprises a gear transmission to allow said one of the first shaft and the second shaft and the guiding unit to rotate at different speeds.

23. The shredder according to claim 22, wherein the drive system comprises a first motor, preferably an electrical motor, for rotating the guiding unit and a second motor, preferably an electrical motor, for rotating one of the first shaft and the second shaft.

24. The shredder according to any of the previous claims, further comprising a collecting unit arranged near the second end of the guiding unit, said collecting unit being configured to collect pieces that have been pushed through a last segment of the sieve.

25. The shredder according any of the previous claims, further comprising a feeding unit for feeding pieces to be shredded to one of the guiding unit and the second side of the first knife assembly near the first end.

26. The shredder according to claim 25, wherein the feeding unit comprises a second knife assembly comprising a plurality of rotatable third knifes that are adjacently arranged in the first direction, and a further guiding unit spaced apart from the second knife assembly and configured to guide pieces that have been cut by the third knifes towards the guiding unit.

27. The shredder according to claim 26, wherein the second knife assembly comprises: a rotatable third shaft extending in the first direction on which the third knifes are mounted; and

a fourth shaft parallel to the third shaft and on which second counter elements are arranged;

wherein each third knife is configured to cooperate with a respective second counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded.

28. The shredder according to claim 27, further comprising fourth knifes mounted to the fourth shaft, and third counter elements mounted to the third shaft, wherein each fourth knife is configured to cooperate with a respective third counter element for the purpose of cutting, punching, tearing or otherwise deforming pieces to be shredded, wherein the third knifes and the third counter elements are alternately arranged on the third shaft, and wherein the fourth knifes and the second counter elements are alternately arranged on the fourth shaft.

29. The shredder according to claim 27 or 28, wherein the third and/or fourth knifes each comprise a disc mounted to the third shaft or fourth shaft, respectively, and comprising an alternating arrangement in the circumferential direction of protruding portions and recessed portions.

30. The shredder according to claim 29, wherein the mounting of the discs of the third and fourth knifes is such that protruding portions of adjacently arranged third knifes and/or the protruding portions of adjacently arranged fourth knifes are arranged with an angular offset relative to each other.

31. The shredder according to any of the claims 27-30, wherein the third and fourth counter elements each comprise a disc preferably having a smooth edge and mounted to the third shaft or fourth shaft, respectively.

32. The shredder according to any of the claims 27-31, wherein the first and third shafts and the second and fourth shafts are integrally connected.

33. The shredder according to any of the claims 25-32, wherein the feeding unit is arranged outside of the guiding unit.

34. The shredder according to any of the previous claims, wherein the guiding unit comprises a drum.