EP1883476A1

EP1883476A1 - Rotor for scrap shredder

Info

Publication number: EP1883476A1
Application number: EP06724423A
Authority: EP
Inventors: Fabio Marcello Rota
Original assignee: Satrind SpA
Current assignee: Satrind SpA
Priority date: 2005-04-27
Filing date: 2006-04-19
Publication date: 2008-02-06
Anticipated expiration: 2026-04-19
Also published as: DE602006002390D1; ATE405346T1; EP1883476B1; WO2006114223A1; ITMI20050757A1

Abstract

A rotor (1) for a scrap shredder consisting of a substantially cylindrical body carrying multiple pairs of blades (41, 42) is described, in which the blades (41, 42) of each pair occupy opposite positions on the surface of the cylindrical body. The blades (41, 42) of each pair are machined at the ends of a body (4) preferably made by pressing and inserted in a through hole (50) made in the body (6) of the rotor (1), to which it is secured by means of retainers (47). Advantageously, the distance between the axes of two adjacent through holes (50) is less than the sum of their radii and hence the rotor (1) has an axial channel in which a coolant flows which directly cools the bodies (4), which carry each pair of blades (41, 42).

Description

ROTOR FOR SCRAP SHREDDER

DESCRIPTION

The present invention refers to a rotor for a scrap shredder (waste, scrap materials, etc) including a supporting structure that carries a loading compartment and at least one rotor (positioned in a seat made in a loading compartment wall) designed to shred the scrap contained in the loading compartment, at least one pusher for pushing the scrap to be shredded against the rotor and means designed to move at the least one rotor and the at least one pusher.

The rotor normally consists of a cylindrical body that carries multiple pairs of blades, which protrude from the rotor and which interact with additional blades fixed to the two sides of the seat in which the rotor is placed.

The blades of each pair normally occupy opposite positions on the rotor surface.

No further design characteristics of the rotor (such as, for example, the layout of the blades along the rotor and/or the presence of a number of annular protrusions - also known as "ribs" - each of which bears a pair of blades and/or the shape of such ribs) will be described herein because they are already known and in any case they are extraneous to the invention.

Rotors for scrap shredders are known in which the blades consist of hard-material plates applied in an already known manner on tool holders carried by the rotor: these known rotors have some drawbacks, including the fact that the application (and the replacement) of such plates is a lengthy and expensive operation because it requires, for each plate, an accurate adjustment to bring it "into register" with the additional blades fixed to the sides of the seat in which the rotor is placed.

Moreover, the heat developed by friction during the scrap shredding heats (or overheats) the scrap during the shredding stage, altering (or being able to alter) its physical-chemical characteristics until it is brought to a melted or semi-melted state, with the consequent complete blockage of the shredder.

In order to avoid this drawback, it is common practice to cool the entire rotor, which not only requires a large number of refrigeration units to be provided and, hence, involves a (rather) high operating cost, but it also entails serious difficulties in cooling the scrap effectively and homogeneously during the shredding stage.

Object of this invention is to develop a rotor for a scrap shredder able to avoid the drawbacks presented by the known rotors; this object is achieved by means of a rotor providing the characterising elements illustrated in claim 1.

Additional advantageous features of the invention are the subject matter of the dependent claims.

The invention will now be described with reference to an embodiment that is purely illustrative (and hence not restrictive) illustrated in the appended figures, where:

- figure 1 shows schematically a perspective view of a rotor according to the invention, without blades;

- figure 2 shows schematically the rotor of figure 1 with a body according to the invention (having a pair of blades) withdrawn from its seat and another body according to the invention partially withdrawn from its seat;

- figure 3 shows schematically a perspective view of a body according to the invention; - figure 4 shows schematically a cross section of the rotor made at the centerline of a body according to the invention;

- figure 5 shows the cross section of figure 4, in which said body has been removed;

- figure 6 shows a portion of the rotor sectioned along a plane passing through the rotor's axis of longitudinal symmetry.

In the appended figures the corresponding elements will be identified by using the same numerical references.

Figure 1 shows schematically a perspective view of a rotor 1 according to the invention, consisting of a cylindrical body (including a tang 2) the external surface of which has multiple ribs 3, parallel to one another, each of which incorporates a through hole 50, which also crosses the cylindrical body, in which a body 4 (figure 3), at each end of which a blade (41, 42) is made, is placed.

Without diverting from the scope of the invention, the ribs 3 may be omitted and the through holes 50 are made only in the cylindrical body. The through holes 50 in which the bodies 4 are inserted are coplanar to one another and each through hole 50 is rotated relative to the adjacent through holes 50 so that the blades (41, 42) of the bodies 4 inserted in the holes 50 are offset from one another in a similar manner to the plates applied to known rotors.

The distance between the axes of longitudinal symmetry of two adjacent through holes 50 is less than the sum of the radii of the holes themselves, which thus interfere in the central area creating a recess 53 (figure 4) which places two adjacent through holes 50 in communication with one another.

Advantageously, the distance between the axes of two adjacent through holes 50 falls between about 85% and about 95% of the sum of the radii of the holes 50 and is preferably about 90% of this sum.

A seat 5 designed to accommodate the retainers 47 (figure 4), which hold the body 4 in the hole 50, is present near each through hole 50, as will be described with reference to figures 4 and 5.

The retainers 47 are not shown in figure 1.

The structure of rotor 1 (number and dimensions of the ribs 3, number and layout of the bodies 4 along the rotor 1, etcetera) will not be discussed herein because it is similar to the structure of the known rotors and in any case it is extraneous to the invention.

Figure 2 shows schematically the rotor of figure 1 with a body 4 withdrawn from the related through hole 50 and another body 4 partially withdrawn from the related through hole 50.

Figure 3 shows schematically a perspective view of a body 4 according to the invention, which includes a tang 45, at each end of which there is a cylindrical body (43, 44) in the shape of a blade (42, respectively 41).

The diameter of cylindrical body 44 is greater than the diameter of cylindrical body 43.

To allow the bodies 4 to be easily inserted into the through holes 50, the radius of the tang 45 of a body 4 must be less than the radius of the related through hole 50 by an amount greater than the difference between the sum of the radii of two adjacent through holes 50 and the distance between their axes of longitudinal symmetry.

Finally, the cylindrical body 44 contains a seat 46 in which the retainers 47 (figure 4) are engaged.

Figure 4 shows schematically a cross section of the rotor 1 made at the centerline of a body 4; figure 4 shows the rotor 1 (sectioned), the adjacent rib 3 and the body 4, inserted in the through hole 50 and held in place by the retainers 47 consisting, in the embodiment described herein, of a screw - inserted in the seat 5 (figure 1) - which engages in the recess 46 (figure 3).

The central part of the tang 45 has been removed to show the recess 53 present in the side wall of the through hole 50 and belonging to the cooling system for the blades (41, 42), which will be described with reference to figure 6.

The annular cavity 52, delimited by the sidewall of the hole 50 and by the tang 45 (the central part of which, removed, has been indicated in figure 4 with dashed lines) also belongs to the cooling system for the blades (41 , 42).

Figure 5 shows the cross section of figure 4, in which the body 4 has been removed to show the section of the through hole 50, which includes three overlapping cylindrical areas with progressively increasing diameter: - a first cylindrical area 54, having a diameter substantially equal to (and in any case not less than) the diameter of the cylindrical area 43 of the body 4;

- a second cylindrical area 55, having a diameter larger than that of the first area 54 but less than that of cylindrical area 44 of body 4, the tang 45 and the second cylindrical area

55 defining an annular cavity 52; - a third cylindrical area 56, having a diameter larger than that of the second cylindrical area 55 and substantially equal to (and in any case not less than) the diameter of the cylindrical area 44 of the body 4.

The recess 53, present in the sidewall of the second area 55 of the hole 50, brings two adjacent annular cavities 52 into communication with one another. A body 4 is applied to the rotor 1 by inserting it in a hole 50 starting from its smaller- diameter area 43 until its area 44 comes in contact with the annular projection 57 which forms a surface connecting the second and the third area (55, 56) of the through hole 50 and by securing it using the retainers 47, inserted in the seat 5 adjacent to the through hole 50, which engage in the seat 46 present in the cylindrical body 44 belonging to the body 4.

When the body 4 is secured in the through hole 50, the blades (41, 42) protrude from the rotor 1.

To install (or to replace) a pair of blades (41, 42) it is sufficient to insert the body 4 into the corresponding through hole 50 (if necessary, after removing the retainers 47 and the body 4 carrying the blades to be replaced) until the area 44 is brought into contact with the annular projection 57, to turn (if necessary) the body 4 to align its seat 46 with the seat 5 and to secure it using the retainers 47, without having to carry out any lengthy and expensive adjustment operations, as required by the known rotors for installing (or for replacing) a plate.

Figure 6 shows a portion of the rotor 1 sectioned along a plane passing through the rotor's axis of longitudinal symmetry.

Figure 6 illustrates the axial hole 61 made inside the tang 2 of the rotor 1 and the multiple through holes 50 - each of which houses a body 4 - interconnected by the recesses 53, whilst it does not show the area of rotor 1 , opposite the area providing the tang 2, in which a further axial hole is made.

For simplicity of graphical representation, figure 6 indicates with the relevant numerical references only one of the bodies 4, of the annular cavities 52 and of the recesses 53.

The bodies 4, the annular cavities 52 and the recesses 53 illustrated in figure 6 do not feature the same form because they are rotated relative to the other.

The recesses 53 present in the side walls of the second cylindrical areas 55 of the through holes 50 place ordinately in communication with one another the axial hole 61, the annular cavities 52 (delimited by the second areas 55 of the holes 50 and by the tangs 45 of the corresponding bodies 4) that surround the tangs 45 and the additional axial hole made in the area of the rotor 1 opposite that where the tang 2 is present.

Inside the rotor 1 there is hence an axial channel (consisting of the axial hole 61, of the annular cavities 52, of the recesses 53 and of the additional axial hole) in which a coolant circulates and directly cools the blades (41, 42) carried by the bodies 4, essentially cooling the mass of the bodies 4 rather than the mass of the entire rotor 1 as it is required for the known rotors: this allows a drastic reduction in the refrigeration units to be provided to keep the blades (41, 42) at a pre-set temperature and, hence, a significant energy saving.

Without diverting from the scope of the invention, a skilled person may make to the previously described rotor all the modifications and the enhancements suggested by the normal experience and/or by the natural technological development.

Claims

1. Rotor (1) for scrap shredder consisting of a cylindrical body, including a tang (2), wherein multiple through holes (50), coplanar to one another and rotated relative to the adjacent through holes (50), are provided, a body (4) - at each end of which there is a blade (41, 42) - being placed in each of said through holes (50), characterized by the fact that the distance between the axes of longitudinal symmetry of two adjacent through holes (50) is less that the sum of the radii of the holes themselves, which interfere in the central area creating a recess (53) which places the two adjacent through holes (50) in communication with one another.

2. Rotor (1) as in claim 1, in which the outer surface of the cylindrical body contains multiple ribs (3) parallel to one another, characterised by the fact that in each rib (3) one of the through holes (50) in which a body (4) is placed is realized, said through hole (50) also crossing the cylindrical body.

3. Rotor (1) as in claim 1, characterised by the fact that the distance between the axes of longitudinal symmetry of two adjacent through holes (50) falls between about 85% and about 95% of the sum of their radii.

4. Rotor (1) as in claim 3, characterised by the fact that the distance between the axes of longitudinal symmetry of two adjacent through holes (50) is about 90% of the sum of their radii.

5. Rotor (1) as in claim 1, characterised by the fact that the body (4) includes a tang (45), at each end of which there is a cylindrical body (43, 44) in the shape of a blade (42, respectively 41).

6. Rotor (1) as in claim 5, characterised by the fact that the diameter of the cylindrical body (44) is greater than the diameter of the cylindrical body (43).

7. Rotor (1) as in claim 5, characterised by the fact that the cylindrical body (44) contains a seat (46) in which retainers (47) designed to secure the body (4) in the through hole (50) are engaged.

8. Rotor (1) as in claims 1 and 5, characterised by the fact that the radius of the tang (45) of a body (4) is less than the radius of the related through hole (50) by an amount greater than the difference between the sum of the radii of the two adjacent through holes (50) and the distance between their axes of longitudinal symmetry.

9. Rotor (1) as in claims 1 and 5, characterised by the fact that each through hole (50) includes the following cylindrical areas of progressively increasing diameter:

- a first cylindrical area (54), having a diameter (substantially) equal to the diameter of the cylindrical area (43) of the body (4);

- a second cylindrical area (55), having a diameter greater than that of the first cylindrical area (54) but less than that of the cylindrical area (44) of the body (4);

- a third cylindrical area (56), having a diameter greater than that of the second cylindrical area (55) and (substantially) equal to the diameter of the cylindrical area (44) ofthe body (4).

10. Rotor (1) as in claim 9, characterised by the fact that the second cylindrical area (55) of each through hole (50) and the tang (45) of the corresponding body (4) define an annular cavity (52).

11. Rotor (1) as in claims 1 and 10, characterised by the fact that two adjacent annular cavities (52) are placed in communication with one another by the recess (53).

12. Rotor (1) as in claim 9, characterised by the fact that a body (4) is applied to the rotor (1) by inserting it in a through hole (50) starting from its smaller-diameter cylindrical area (43) until its cylindrical area (44) comes into contact with an annular projection (57) which forms a connecting surface between the second and the third cylindrical areas (55, 56) of the through hole (50) and by securing it by means of retainers (47), inserted in a seat (5) adjacent to the through hole (50), which are engaged in a seat (46) in the cylindrical body (44) belonging to the body (4).

13. Rotor (1) as in claim 12, characterised by the fact that, in order to replace at least one blade (41, 42), the retainers (47) and the body (4) carrying the at least one blade (41, 42) to be replaced, already located in a through hole (50), are removed before inserting a new body (4) in the through hole (50).

14. Rotor (1) as in at least one of the previous claims, characterised by the fact that axial holes are provided inside the tang (2) of the rotor (1) and inside the area of the rotor (1) opposite that containing the tang (2), by the fact that the recesses (53) present in the side walls of the second cylindrical areas (55) of the through holes (50) place ordinately in communication with one another the axial hole present in the tang (2), the annular cavities (52) surrounding the tangs (45) of the bodies (4) and the additional axial hole made in the area of the rotor (1) opposite that containing the tang (2) and by the fact that in an axial channel, located inside the manner rotor (1) and consisting of the axial hole present in the tang (2), of the annular cavities (52), of the recesses (53) and of the additional axial hole made in the area of the rotor (1) opposite that containing the tang (2), a coolant is made to flow that cools the bodies (4) for cooling the blades (41, 42) carried by the bodies (4).