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(11) | EP 0 970 749 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Crushing device for plastics, cardboard and the like |
(57) A Device (1) for crushing plastic materials, cardboard, wood, foamed plastic, plastic
bottles end the like, using a rotor (11) with cutting bodies (3) co-operating with
a fixed counter-cutting element (5), comprises:
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[0001] The present invention refers to a device for crushing plastic materials, cardboard, wood, foamed plastic, plastic bottles and the like.
[0002] In particular the invention refers to a crushing device, making use of a rotor provided with cutting bodies co-operating with a fixed counter-cutting element, for polypropylene or cardboard or wood boxes, or other light recyclable materials as for example PET bottles or foamed plastic food trays.
[0003] Crushing devices are normally used for triturating waste in general, waste materials from wood manufacture or glass, ceramics or the like.
[0004] Known crushers can be classified in some main categories, according to the material to be crushed and the working principle.
[0005] For example a crusher for wood or cardboard normally comprises a rotating drum, having on its surface a plurality of cutting or crumbling protrusions, driven at high speed by a high power motor. The material to be crushed is pressed towards the rotating drum surface and consequently crushed in small fragments.
[0006] A second type of crusher, commonly known as mill, has an hollow cylinder in which rotates at high speed a rotor comprising a rotating shaft and some hammers, normally hinged to the shaft itself and therefore partially movable.
[0007] The moving hammers and the co-operation with the internal surface of the cylinder causes crushing of the materials placed inside.
[0008] The crushing hammers can be provided with blades for facilitating cutting of not too hard materials, as plastics, light wood or cardboard.
[0009] Crushers and mills present on the market are always very huge, as they are designed for the treatment of large amount of materials.
[0010] It is not always possible, or however not economically favourable, to realise a small crusher using the same working principle as the large ones.
[0011] For treatment of some light materials, as for example polypropylene boxes for fruit and vegetables, plastic boxes in general, PET bottles and cardboard, and in order to maintain economically convenient recycling of those materials, would be necessary crushing devices particularly simple, small, with easy maintenance and low production and operating costs.
[0012] A first object of the present invention is therefore to solve the problem of how to realise a crushing device for light materials, small, economically convenient and with easy maintenance.
[0013] The above and other objects are reached from the crushing device according to the present invention, as claimed in the accompanying claims.
[0014] The crushing device according to the present invention can be advantageously used for crushing plastic, wood or cardboard boxes, bottles or food containers in general, making the recycling process more efficient and cheap.
[0015] The above and other objects of the invention will result more clear from the description of a preferred embodiment with reference to the accompanying drawings in which:
figure 1 shows a top view of a crushing block of a device according to the present invention;
figure 2 shows a front view of a crushing block of a device according to the present invention;
figure 3 shows in particular some hammers used in the crushing block of a device according to the present invention;
figure 4 shows a particular of a hammer and a counter-cutting element of a device according to the present invention; and
figure 5 shows a lateral global view of a crushing device according to the present invention.
[0016] With reference to figures 1 and 2 a cutting block 1, incorporated in a crushing device for crushing plastic materials, cardboard, wood, foamed plastic, plastic bottles and the like, comprises a rotor 11 having cutting bodies 3 co-operating with a fixed counter-cutting element 5.
[0017] The block 1 has a supporting structure which supports a rotating shaft 2 on which are inserted some hammers 3 placed side by side.
[0018] On the two extremities of the rotating shaft 2 are fastened two belt pulleys. A first pulley 6 joins the shaft, by means of a rubber belt 7, with a main electric motor 61, while a second pulley 8, preferably incorporating a flywheel, is eventually used to drive other moving parts in the same machine, described later on.
[0019] The supporting structure of the crushing block 1, visible in figure 2, comprises fundamentally two lateral square walls 22 and 23 joined, in correspondence of vertices, by four transversal bars, two of which are visible in figure 2 with numeral references 24 and 25.
[0020] Each wall has in the middle a hole in which is inserted, by means of suitable bearings, the rotating shaft 2.
[0021] This compact structure of the crushing block 1 makes the block itself independent from the machine allowing an easy and rapid separation from the frame 10 in case of routine maintenance or for a quick replacement.
[0022] On the rotating shaft 2 are firmly inserted a plurality of hammers 3 having an elongated shape, radially offset one to each other to form an helicoid.
[0023] The central portion of the rotating shaft 2, which supports the hammers, has a square section.
[0024] The hammers have in their central portion a squared opening having dimension so that they can be inserted, side by side, on the rotating shaft.
[0025] In order to obtain a correct angle between adjacent hammers, the hammers, which have all substantially the same shape, have each a squared central opening rotated of six degrees in respect to the opening of an adjacent hammer.
[0026] In this way, inserting the hammers correctly on the shaft, it is obtained an helicoid of 180 degrees around the rotating shaft 2, being the hammers thirty in total.
[0027] Each hammer, visible in detail in figure 3, comprises two symmetric opposite portions, each having on its extremity a cutting surface 4 able to co-operate with a counter-cutting element 5.
[0028] The counter-cutting element 5 is a bar made of hardened metal or stainless steel, with a counter-cutting surface having a shape complementary to the shape of hammer's extremities.
[0029] In this embodiment, where the hammers have two different lengths and are positioned in an alternating way on the rotating shaft, the counter-cutting element 5 has some protrusions and some recesses corresponding respectively to the shorter and to the longer hammers.
[0030] Alternatively the hammers could have all the same length and, consequently, the counter-cutting element could have a linear counter-cutting surface.
[0031] However, experimental tests showed that the prototype having hammers of different alternating lengths was more efficient.
[0032] The cutting surfaces of hammers 3 are realised by means of hardened metal cutting bodies 4 fastened with screws 41 in recesses 12 obtained on the extremities of the hammers themself.
[0033] The cutting bodies 4 are squared and are sharpened on four sides in such a way that they can be rotated, inside recesses 12, by 90 or 180 degrees. This expedient extends their life, as they can be rotated at least four times, and makes easier the periodic maintenance of the device.
[0034] Figure 3 shows in particular four hammers, two longer and two shorter, inserted alternately on the rotating shaft 2.
[0035] In figure 4 is shown the co-operation of a hammer 3 with a counter-cutting element 5 in a cutting phase. As can be noted the hammer's cutting surface meets the counter-cutting surface with an angle α of a few degrees.
[0036] This expedient favours cutting and reduces hammer's impact on the counter-cutting element, using a working principle similar to that of scissors.
[0037] Moreover the total number of hammers and the angular difference between adjacent hammers are calculated so that, during rotation of the shaft, only one cutting body is in a cutting phase in a particular moment.
[0038] This way the electric motor that drives the rotor is solicited in a continuous way and can work with a relatively limited power.
[0041] The crushing block 1 is inserted in an apposite space in a metallic supporting frame 10. Four foot adjustable in height, two of which 54 an 55 are visible in figure, lay the frame on ground.
[0042] The crushing block 1 receives from the top the material to be crushed by means of a slide 56 having a forced dragging system.
[0043] In particular a second electric motor drives at reduced speed one or more driving belts 57 tight between two pulleys 58 and 59 and a series of toothed disks 60 that drag and push materials in the co-operating zone between hammers 3 and counter-cutting element 5.
[0044] Around rotor 11 furthermore is preferably provided a shield 13 made of punched plate that joins together with slide 56 in order to avoid relevant parts of material, eventually dragged by rotor 11 beyond counter-cutting element 5, being conveyed with the crushed material.
[0045] Said shield 13 allows to said relevant parts of material to rise in the sense of rotation of rotor 11 and to be further on crashed by rotor 11 while passing against counter-cutting element 5.
[0046] Crushed material is collected under crushing block 1 in a funnel shaped container 52 whose output is connected to an output channel 53 coming from a pusher fan 51.
[0047] Pusher fan 51 is driven by the main electric motor 61 by means of a driving belt 9 joined with the second pulley 8 of the crushing block 1.
[0048] Air pushed by fan 51 in the output channel 53 causes an eddy inside container 52, crushed material is efficacy and rapidly removed from the crushing machine and can be sent to a collecting container.
[0049] Advantageously can be provided a ramification in the channel that permits to send to different containers different materials as plastics, cardboard or wood.
[0050] In an economic version of crusher it will be also possible that fan 51 is replaced by a drawer for collecting crushed material, placed directly under shield 13 or in the space where is placed the fan 51.
[0051] In a such configuration, the output channel 53 will be closed by a removable lid so that crushed material can be collected in the drawer.
[0052] The metallic supporting frame 10 moreover can be easily covered by sound-proofing material, in order to silent the machine and allow the installation in a working ambient.
[0053] The crushing device described can be realised, substantially without structural modifications, in various dimensions.
1. Device for crushing plastic materials, cardboard, wood, foamed plastic, plastic bottles
end the like, using a rotor (11) with cutting surfaces (4) co-operating with a fixed
counter-cutting element (5), characterised in that it comprises:
- a supporting frame (10) supporting a rotating shaft (2);
- a plurality of hammers (3) having an elongated shape, fastened to said rotating shaft (2) and arranged on it radially offset one to each other to form an helicoid, each hammer having at least a cutting surface (4) on an extremity;
- a counter-cutting element (5) for said plurality of hammers (3), fastened to the supporting frame (10), with a counter-cutting surface having a shape complementary to the shape of the hammer's extremities.
2. Device according to claim 1, characterised in that each hammer (3) is fastened in
its central portion to the rotating shaft (2) and comprises two symmetric opposite
portions, each portion having a cutting surface able to co-operate with said counter-cutting
element (5).
3. Device according to claim 2, characterised in that each hammer (3) comprises, as cutting
surfaces, two cutting bodies (4) made of hardened metal and fixed on its two opposite
extremities.
4. Device according to claim 3, characterised in that said cutting bodies (4) have a
squared shape, are put inside a corresponding recess (12) obtained on hammer's extremities
and are fixed to them by means of screws (41).
5. Device according to claim 4, characterised in that said cutting bodies (4) are sharpened
on four sides and can be rotated, inside said recesses (12), of 90 or 180 degrees.
6. Device according to claim 2, characterised in that the hammers (3) have two different
lengths and are positioned alternately on rotating shaft (2), and the counter-cutting
element (5) has some protrusions and some recesses corresponding respectively to the
shorter and to the longer hammers.
7. Device according to claim 2, characterised in that the rotating shaft (2) has at least
a squared section portion and the hammers (3) have in the middle a squared opening
and are inserted side by side on the rotating shaft.
8. Device according to claim 7, characterised in that each hammer has the central opening
rotated of a few degrees in comparison with the opening of an adjacent hammer.
9. Device according to claim 8, characterised in that the hammers (3) are offset one
to each other of six degrees.
10. Device according to claim 9, characterised in that the hammers (3) are thirty and
form a 180 degrees helicoid around the rotating shaft (2).
11. Device according to claim 1, characterised in that it comprises a pulley (6), fastened
to the rotating shaft (2), which joins the rotating shaft (2) with a main electric
motor (61) by means of a first belt (7).
12. Device according to claim 11, characterised in that the same electric motor (61) drives,
by means of a second belt (9), a pusher fan (51) which removes, through apposite channels
(52,53), the crushed material.
13. Device according to claim 12, characterised in that it comprises an input slide (56)
for material to be crushed having belts (57) and toothed disks (60), driven by a second
electric motor, that draw by force the material in correspondence of the co-operating
zone between the hammers (3) and the counter-cutting element (5).
14. Device according to any of the preceding claims, characterised in that it comprises
furthermore a punched shield (13) for avoiding that relevant parts of material, eventually
dragged by rotor (11) beyond counter-cutting element 5, being conveyed with the other
crushed material.