US3847361A

US3847361A - Comminutor for bulky objects

Info

Publication number: US3847361A
Application number: US00323925A
Authority: US
Inventors: A Heger
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-01-15
Filing date: 1973-01-15
Publication date: 1974-11-12
Anticipated expiration: 1991-11-12

Abstract

A breaker unit has a housing, provided with an inlet opening and an outlet opening and intermediate them with two transversely spaced parallel rotatable shafts driven by an electromotor and each carrying a plurality of axially spaced breaker elements. An additional shaft carries tines which can be inserted between axially adjacent ones of the breaker elements to a greater or lesser degree by turning the additional shaft. A comminuting unit is arranged to receive fragments of bulky objects which have been broken up in the breaker unit and for comminuting them to a desired size.

Description

ilnited States Patent 11 Heger Nov, it, 1974 COMMINUTOR FDR BULKY OBJECTS lnventor: Alois Heger, 7031 Oberjesingen, Wurtenberg, Germany Filed: Jan. 15, 1973 Appl. No: 323,925

11.8. C1 241/1152, 241/29, 241/68 llnt. C1. B02c 9/04 Field of Search 241/152, 154, 29, 68, 69,

ReferencesCiteul UN1TED STATES PATENTS 4/1967- Stephan et al. 241/152 X 6/1971 Pfalz et a1. 241/29 Primary Examiner-RoyLake Assistant Extzminew-DeWalden W. Jones Attorney, Agent, or Firm-Michael S. Striker [57] AlBSTRAL CT SlZe.

' 20 Claims, 6 Drawing Figures PATENTEDNUV 12 m4 3; 847361 SHEET 10F 4 PATENTEDNUV 12 V37 3.847361 SHEET 2 [IF' 4 Fig.2

BACKGROUND OF THE INVENTION tion of the breaker unit can be accommodated to the particular material of the objects to be comminuted, and to the size of these objects, and it is also possible to influence the size'of the fragments into which the ob- The present invention relates generally to a commi- 5 jects will bebroken up in the breaker unit.

nutor, and more particularly to a comminutor for bulky objects. Still more particularly the invention relates to a comminutor for bulky but light-weight objects, such as objects made of porous synthetic plastic, for instance of the type based upon styrene or styrol.

It is very difficult to mechanically comminute bulky objects of lightweight, especially if the comminution is to be carried out rapidly and if a uniform specific particle size is to be obtained. The latter, in particular, is frequently desired because the particles are to be used for further purposes, for instance as a raw material for making other objects.

investigations have shown that conventional hammer mills or other comminutors frequently cannot receive bulky objects of such size, and that their hammers or other comminuting instrumentalities cannot properly break up the objects, aside from the fact that the comminuting speed is not as high as desired. This is particularly true in the case of light-weight bulky objects, for

instance objects made of polystyrene or of the trademarked material Styropor. This material is widely used for making packaging materials, that is sheets, boxes, crates andthe like, which are discarded after their contents have been removed and which then must be comminuted so that their material can be re-used.

SUMMARY OF THE INVENTION It is a general object of the present invention to overi come the disadvantages of theprior art. n More particularly, it is anobject of the present invention to provide a novel comminutor capable of properly comminuting bulky objects, particularly light-weight bulky objects.

Another objectofthe invention is to ,providesuch a comminutor which isparticularly well suited for comminuting bulky objects of synthetic plastic material, and particularly of porous polystyrol or polystyrene.

- Another object of the invention is to provide such a comminuting unit which is relatively small in its dimenrality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with these shafts for rotating the same, and-a plurality of projections each insertible between two axially consecutive breaker elements on'the respective shaft'to differnt selectable extents, so that objects entering through the inlet opening are broken up into fragments by. cooperation of the breaker elements and projections. In addition, the novel comminutor comprises a comminuting unit which is arranged-to receive the fragments through the outlet opening and serves to comminute the fragments to desired size.

Depending upon the position of the projections be tween and relative to the breaker elements, the opera- The breaker unit will'operate particularly advantageously if the breaker elements thereof are in form of double-armed levers and if axially consecutive ones of the breaker elements on the respective shafts are always angularly offset relative to one another on the shaft by approximately 180.

It is important that the incoming objects do not only have grooves or scratches torn into them, but that they be actually broken up into fragments. This is achieved if the ends of the double-armed lever are bent oppositely towards one another out of a plane normal to the shafts on which the breaker elements are mounted. In this manner the objects to be comminuted are reliably engaged and are drawn between the breaker elements, where they are broken up andthen advanced to the comminuting unit. The shafts with the breaker elements are advantageously rotated in mutually opposite directions.

It is particularly advantageous if the housing of the breaker unit is of rectangular interior outline at the level of the breaker elements, and if the shafts on which the breaker elements are mounted extend in parallelism with the longitudinal sidewalls of the housing, the spacing of the ends of the breaker elements which face towards one another corresponding approximately to the distance of the ends of the breaker elements facing the sidewalls, to these sidewalls. This distance is determined by the largest permissible particle size which is to be, obtained after the bulky objects have been broken up into fragments but beforethey undergo comminution in the comminuting unit.

The projections are advantageously mounted on an additional shaft which is turnably journalled in the housing, and the projections may be in form of plates.

The additional shaft can be incrementally turned so that the projections can be moved between or out of the spaces between adjacent ones of the breaker elements to selected degrees. Advantageously the plates, if such are used, will have supporting edges all of which together form a grid which in the center position of the element used for effecting the incremental adjustment of the additional shaft will be located at least substantially horizontally. in this center position the supporting edges which together make up the grid are located approximately in an intermediate plane between the plane passing through the shafts on which the breaker elements are mounted, and a plane through the ends of the upper portions of the breaker elements.

Although it is not necessary to close the inlet opening in any way, that is the inlet opening to the housing of the breaker unit, it is nevertheless advantageous to do so in order to reduce the danger of accidents and of the effected by providing pivotable doors which are jourwhich at least one cutter element is provided which rotates at least substantially horizontally and is motordriven. The housing may accommodate a screen insert in which the cutter element rotates and it will receive the fragments from the housing of the breaker unit. The fragments 'will have a certain maximum size, determined in a manner still to be discussed in more detail, and they will be further comminuted in the comminuting unit to a final desired size, such that they can pass through the apertures .of the screen insert and can leave through the outlet of the housing of the comminuted unit. Thus; the final particle size depends upon the size of the openings in the screen insert, which may advantageously be configurated as a screenfcylinder in which the cutter element rotates closely adjacent to and above the bottom wall thereof.

Particularlyif the objects to be comminuted are of porous polystyrol or styrene, it is advantageous to have the outlet of the comminuting unitdischarge into a funnel which conducts the'particles into a wind chamber from where they .can be then blown into a large receptacle, because within a relatively short period of time of operation large volumes of material are obtained which must of course be rapidly moved out of the way.

According to a currently preferredembodiment both the cutter element and an impeller of a blower for the wind chamber are mounted on opposite ends of a vertical shaft of which one end is located in the housing of the comminutor unit and the other end in the wind chamber." A motor drives the shaft. The novel features which are considered as characteristic for the invention Extending in parallelism with the longitudinal sidewalls 8 and 9 (FIG. 4) of the housing 5, and in parallelism with one another, are two shafts l and l] which are journalled for rotation and which each carry a pluare placed onto the respective shaft H0 or it and secured in known manner thereto. The end portions l and 16 of the breaker element 12 are of sickle-shaped configuration and are pointed asparticularly clearly seen in FIG. 6. In addition, these endportions l5, 16 are bent in mutually opposite directions out of a plane normal to the shaft or 11 on which the respective breaker elements 12 are mounted. It will be seen in FIG. 4 that the axially consecutive double-armed levers 13 are offset through 180 relative to one another on I the

respective shafts

10 or 11.

are set forth in particular in the appended claims. The I FIG. 1 is a somewhat diagrammatic front view of a comminutor-according to the present invention;

FIG. 2 is a side view of the comminutor in FIG. 1;

FIG. 3 is a top-plan view of the comminutor in FIGS.

1 and 2;

FIG. 4 is a section taken on line IV-IV of FIG. 2;

FIG. 5 is a detail view, on an enlarged scale, of a breaker element as seen from the side; and

FIG. 6 is a front view of a breaker element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Discussing the drawing now in detail it will be seen that in FIGS. l-4 there is illustrated a novel comminuting apparatus according to the present invention. It has a comminuting unit 1 and a breaker unit 2. The breaker unit 2 is so mounted on the comminuting unit 1, and retained in place, that an outlet opening 3 of the breaker unit 2 communicates with an inlet 4 of the comminuting unit 1. I

The breaker unit 2 has a housing 5 of here rectangular cross-section, provided at the upper end with a large inlet opening 6 and at the lower end with the smaller outlet opening 3. Intermediate them, the housing 5 has funnel walls 7 reducing its cross-section to the smallerdimensioned outlet opening 3 from the larger dimension of the inlet opening 6.

In the illustrated embodiment the spacing 17 of the ends of the breaker elements 12 facing the longitudinal sidewalls 8 and 9 from the longitudinal side walls 8 and 9 themselves corresponds to the distance 18 between the facing'ends of the breaker elements 12. These distances 17 and 18 are in part determinative of the size of the particles obtained during breaking-up of objects in the breaker unit 2. v

A motor. 19 is mounted at the exterior of the housing 5 and drives

gears

20, 21 which in turn mesh with gears 22, 23 directly mounted on the

shafts

10,11. The latter are thus driven in mutually opposite directions, i.e. one is driven in right-hand rotation and the other is driven in left-hand rotation.

There is further provided an element which for purposes of this description will be called a rake 24, having a shaft 27 journalled for turning movement in the housing 5 and carrying tines 25 which in this embodiment are configurated of sheet-metal plates 26. An adjusting member 28 (FIG. 2) is provided in form of a lever which permits incremental turning of the shaft 27. The plates 26 each are substantially of a quarter-circle configuration and at one end of the quarter circle there is located the shaft 27. The other end of the quater-circle is provided with a planar supporting edge 29 the plurality of which, when the member 28 is in the middle posi tion thereof, is located in an at least approximately horizontal plane. This plane is approximately midway between a plane passing through the

shaft

10, 11 and a plane passing through the ends of the upper arms of the double-armed levers 13. It follows that the supporting edges 29 together constitute a grid through which the portions of objects to be broken up are pulled by the breaker elements 12. Depending upon the adjustment of the thus-obtained grid, that is depending upon how the shaft 27 is turned incrementally, the conditions under which the material is pulled through this grid are varied, so that by incremental adjustment of the shaft 27' it is possible to accommodate the arrangement to the particular type of material which the objects to be broken up are composed, to the size of the objects, to the output of the motorand to the throughput speed. Evidently, the member 28 can be arrested in the various positions. 7

Because large and bulky objects are to be capable of being inserted into the housing 5, the inlet opening 6 is very large in dimension. It is closed by doors or flaps 30, 31 which are provided with

balance weights

32, 33

so that they are readily movable to open position but will be automatically returned to closed position by the balance weights. The

doors

30, 31 areof course pivot- I opening 3 of course can be substantially smaller than the inlet opening 6, because the size of fragments reaching the outlet opening 3 will be strictly reduced.

As seen in FIG. 1, the outlet opening 3 discharges into the inlet opening 4 of the comminuting unit 1 which has a container 35 provided with apertures 36 and accommodated with spacing in a housing 34. Within the container 35, which may also be thought of as a screen insert, above and approximate to the bottom wall 37 thereof, there is provided a cutter element 38 which rotates in parallelism with the bottom wall 37 in a horizontal plane. The cutter element 38 is mounted on the upper endiportion of avertical shaft 39 at the other end of which is located a drive which is driven by a motor 40, as well as an impeller 4 producing a stream of impelling air. The shaft 39 is appropriately journalled inthe housing 34.

The inlet 4 opens from above into-the receptacle 35 and a dosing arrangement 42 regulates the inflow of fragments. The outlet 43 is constituted by that portion which is located between the container 35 andthe It will be understood that each of the elements described above, ortwo or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been; illustrated and described as embodied in a comminuter for bulky objects, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying currentkn'owledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended tobe comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, an outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive couple-d with said shafts for rotating the same, and a plurality of projections each ments on the respective shafts to different selectable housing 34 and merges into a-funnel 44 via whichthe v finally. comminuted particle enter into a wind chamber 45 from where the stream of air produced by the impeller 41 expells them through a channel 46.

When objects are inserted into the opening 6, for instance bulky porous polystyrol packingmaterial, the

doors

30, 31 will swing out of the way and permit the object to move to the region of the breaker elements 12. These engage and pull the objects through the tines of the rake 24, breaking them up into fragments having a size which in part is determined by the position of the grid defined by the several supporting edges 29. The direction of rotation'of the breaker elements 12 is indicated in FIG. 2 by the

arrows

47, 48..

The thus-obtained fragments slide on the inclined walls 7 and pass through the outlet opening 3 into the inlet opening 4 of the comminuter unit 1, from where they enter into the receptacle 35. Here they are further comminuted by the cutter element 38 whichrotates at high speed, until they have reached a particle size small enough to pass through the apertures 36 and into the outlet 43 from where they pass into the funnel 44. Evidently, the finally obtained particle size depends upon the size of the apertures 36 which may also be provided in the bottom wall 37. It is advantageous to make the receptacle 35 readily exchangeable for other receptacles having differentaperture sizes so as to be able to vary the size of the final particles,

The present invention provides, as will be seen, a comminutor which is relatively small in its dimensions but which makes it possible to rapidly and without difficulty first break up and then comminute bulky objects, particularly objects of light weight. A relatively small motor output is required for operation of the novel comminutor and the desired particle size of the comminuted material can be quite-readily adjusted at will.

extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit including a casing having an inlet communieating with said outlet opening for receiving said fragments therefrom and an outlet, a containerprovided with a plurality of apertures and accommodated in said casing intermediate said inlet and outlet thereof, and having a bottom wall, and at least one rotary cutter located within the confines of said container and extending substantially parallel to said bottom wall in close proximity thereof and being mounted for rotation with respect to said container so as to comminute said fragments and expel such comminuted fragments through said apertures to the exterior of said container from where they proceed.

2.A comminutor as defined in claim 1, wherein said breaker elements are double-armed levers.

3. A comminutor as defined in claim 2, wherein axially consecutive ones of said levers are angularly offset relative to one another and about the respectively associated shaft by substantially 4. A comminutor as defined in claim 2, said levers having end portions which are bent over in mutually opposite directions out'of planes normal to the axes, of said shafts.

5. A comminutor as defined in claim 2, wherein said levers have sickle-shaped pointed end portions.

6. A comminutor as defined in claim 1, wherein said drive rotates said shafts in mutually opposite directions.

ing a housing of substantially rectangular interior crosssection and provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts extending in parallelism with respective side walls of said housing, a plurality of breaker elements-mounted on the respective shafts for rotation therewith and axially spaced therealong so that the closest spacing between axially consecutive ones of said breaker elements substantially corresponds to the distance between said breaker elements and said side walls, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projectionsyand a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size.

8. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the. same, a plurality of projections each insertablebetween two axially consecutive breaker elements on therespective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections, and adjusting means for adjusting the position of said projections relative to said breaker elements; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size.

v 9. A comminutor as defined in claim 8; further comprising a mounting shaft which is turnably journalled in said housing and from which said projections extend; and wherein said adjusting means includes an adjusting lever operatively associated with said mounting shaft for effecting incremental turning of the same.

10. A comminutor as defined in claim 9, wherein said projections are plate members.

11. A comminutor as defined in claim 9, wherein said projections each have a planar supporting edge, and wherein said supporting edges together constitutea grid which-in one position of said projections has an at least substantially horizontal orientation.

12. A comminutor as defined in claim 11, wherein said horizontal plane is located substantially midway between a plane passing through said mounting shaft and a plane passing through the respectively upper end portions of said breaker elements.

13. A comminutor'as defined in claim 10, wherein said plate members have substantially the form of quarter circles, and wherein said mounting shaft is located substantially at the intersection between a plane passing through lower end portions of said breaker elements and a plane paralleling said side walls, intermediate one of said side walls and one of said shafts.

14. A comminutor as defined in claim 1; further comprising closure means for closing said inlet opening.

15 A comminutor asdefmed in claim 14, said closure means comprising doors which are pivotably jour nalled in the region of side walls of said housing, and balance weights provided on said doors.

16. A comminutor as defined in claim 1, .said drive comprising a motor mounted at the exterior of said housing, gears on said shafts, and drive gears driven by said motor and meshing with said gears on said shafts.

l7. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opcning,a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced there along and for rotation therewith, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit arranged to receive said fragments through saidoutlet opening for comminuting the fragments to desired size, said breaker unit and said comminuting unitbeing discrete units connectable to one another.

18. A comminutor as defined in claim 7, wherein said comminuting unit comprises-a casing having an inlet communicating with said outlet opening, and an outlet, at least one rotary cutter mounted for at least substantially horizontal rotation in said casing, and a motor for rotating said cutter.

19. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size, and including a casing having an inlet communicating with said outlet opening, and

Claims

1. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, an outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit including a casing having an inlet communicating with said outlet opening for receiving said fragments therefrom and an outlet, a container proVided with a plurality of apertures and accommodated in said casing intermediate said inlet and outlet thereof, and having a bottom wall, and at least one rotary cutter located within the confines of said container and extending substantially parallel to said bottom wall in close proximity thereof and being mounted for rotation with respect to said container so as to comminute said fragments and expel such comminuted fragments through said apertures to the exterior of said container from where they proceed.

2. A comminutor as defined in claim 1, wherein said breaker elements are double-armed levers.

3. A comminutor as defined in claim 2, wherein axially consecutive ones of said levers are angularly offset relative to one another and about the respectively associated shaft by substantially 180*.

4. A comminutor as defined in claim 2, said levers having end portions which are bent over in mutually opposite directions out of planes normal to the axes of said shafts.

7. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing of substantially rectangular interior cross-section and provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts extending in parallelism with respective side walls of said housing, a plurality of breaker elements mounted on the respective shafts for rotation therewith and axially spaced therealong so that the closest spacing between axially consecutive ones of said breaker elements substantially corresponds to the distance between said breaker elements and said side walls, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size.

8. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the same, a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections, and adjusting means for adjusting the position of said projections relative to said breaker elements; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size.

9. A comminutor as defined in claim 8; further comprising a mounting shaft which is turnably journalled in said housing and from which said projections extend; and wherein said adjusting means includes an adjusting lever operatively associated with said mounting shaft for effecting incremental turning of the same.

11. A comminutor as defined in claim 9, wherein said projections each have a planar supporting edge, and wherein said supporting edges together constitute a grid which in one position of said projections has an at least substantially horizontal orientation.

13. A comminutor as defined in claim 10, wherein said plate members have substantially the form of quarter circles, and wherein said mounting shaft is located substantially at the intersection between a plane passing through lower end portions of said breaker elements and a plane paralleling said side walls, intermediate one of said side walls and one of said shafts.

15. A comminutor as defined in claim 14, said closure means comprising doors which are pivotably journalled in the region of side walls of said housing, and balance weights provided on said doors.

16. A comminutor as defined in claim 1, said drive comprising a motor mounted at the exterior of said housing, gears on said shafts, and drive gears driven by said motor and meshing with said gears on said shafts.

17. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size, said breaker unit and said comminuting unit being discrete units connectable to one another.

18. A comminutor as defined in claim 7, wherein said comminuting unit comprises a casing having an inlet communicating with said outlet opening, and an outlet, at least one rotary cutter mounted for at least substantially horizontal rotation in said casing, and a motor for rotating said cutter.

19. A comminutor for bulky objects, particularly objects of porous styrene, comprising a breaker unit having a housing provided with an inlet opening, a smaller outlet opening, at least two transversely spaced parallel rotatable shafts, a plurality of breaker elements mounted on the respective shafts axially spaced therealong and for rotation therewith, a drive coupled with said shafts for rotating the same, and a plurality of projections each insertable between two axially consecutive breaker elements on the respective shafts to different selectable extents, so that objects entering through said inlet opening are broken up into fragments by cooperation of said breaker elements and projections; and a comminuting unit arranged to receive said fragments through said outlet opening for comminuting the fragments to desired size, and including a casing having an inlet communicating with said outlet opening, and an outlet, a funnel communicating with said outlet and with a wind chamber, at least one rotary cutter mounted for at least substantially horizontal rotation in said casing, and a motor for rotating said cutter.

20. A comminutor as defined in claim 19, further comprising an upright shaft extending into said casing and having one end portion located in the latter and carrying said cutter, and another end portion located in said wind chamber and carrying an impeller, said motor rotating said upright shaft.