GB2080145A - Cutting and shredding equipment - Google Patents

Abstract

A garden refuse shredder possesses a three-bladed rotary shaft 1 in which the straight blade edges 5, 6 and 7 shear material against the inclined sharp edges 9, 10, 11 and 12 of orifices in a surrounding stationary housing which define an upper opening 8 beneath a hopper and a lower outlet 8a for gravity escape of the shredded material. (Fig. 1) <IMAGE>

Description

SPECIFICATION Cutting and shredding equipment This invention relates generally to cutting or shredding equipment suitable for the subdivision of material usually elongate material into random short lengths. The equipment is capable of use in a wide range of industrial uses e.g. in size reduction of sheet or stick material such as naturally occuring woody or vegetable material, and such as polymer sheet. Moreover, it can be used in size reduction of random lump material e.g. mineral or constructional materials. It is also capable of use in foodstuffs, production e.g. in grinding or cutting up meat. There are also a range of agricultural uses e.g. in the subdivision of root crops for animal food.

Most especially however the invention is concerned with garden equipment, and particularly with shredders for reducing garden refuse into a subdivided state to assist composting, and for convenience in view of its wide range of potential utility it will be described in this context.

British Patent Application No. 2 012 565 shows equipment designed for this purpose.

In the device described in this British Patent Application, a hopper is positioned over a cylindrical housing within which is a coaxial rotary shaft mounting an elliptical blade at an angle. Rotation of the shaft within the cylindrical housing causes the edges of the elliptical blade to cooperate with the edges of orifices extending along the housing, thereby providing cutting edges to subdivide the material in the hopper and providing outlets through which that material can be caused or allowed to fall out of the housing into a suitable pile or into a container.

This prior equipment depends for its action upon the use of an elliptical blade. However, I have now established that a straight rectilinear blade would be easier to manufacture, and would be easier to maintain and sharpen in use. Also, it would possess uniform strength along its length, and provide a cutting edge at a uniform distance from the rotary axis, whereby the shearing force exerted would be uniform at all points.

In one aspect the invention provides cutting or shredding equipment in which there are arranged for relative rotation about an axis: (a) an inner member with at least one inner member blade means having a substantially straignt outer cutting or shearing edge, wherein when two or more of such inner member blade means are present their outer cutting or shearing edges, in any cross-section at right angles to the axis, are equidistant from the axis, said outer edge or edges being substantially coplanar with the axis, (b) an outer member with at least one outer member blade means having an inner cutting or shearing edge where when two or more such outer member blade means are present their inner cutting or shearing edges, at the said cross-section at right angles, are equidistant from the axis and effectively at the same distance from the axis as the cutting or shearing edges of the inner member blade means, said inner edge or edges not being coplanar with the axis, whereby relative rotation provides cutting or shear between the inner and outer blade edges.

Preferably inner member can rotate against a stationary outer member; but the converse situation, or contrarotation, or co-rotation at different speeds, are also possible.

A central rotary shaft or axis with two, three or more projecting blades substantially coplanar with the axis and with substantially straight and parallel outer edges can be used as the inner member.

However, the edges need not be parallel; for example, blades tapering along the axis (for location within a complementary outer housing as the outer member) could be envisaged. Also the edges of such blades could be interrupted to give a succession of separate blade edge portions, especially if two or more blades with mutually staggered interruptions are used.

An outer housing provided with two or more blades can be used as the outer member. As long as its blades are located for interaction as defined above it need not be of any particular appearance. However, for convenience a cylindrical coaxial housing in which blade means are defined at the edges of orifices in the housing, is particularly valuable.

In another aspect therefore the invention provides cutting or shredding equipment for use in subdivision of elongate vegetable garden refuse, comprising: (a) an inner rotary member haing an axis of rotation and provided with ar least one blade having an edge substantially parallel to and substantially coplanar with the axis, (b) a surrounding stationary housing with a coaxial inner curved surface over which the or each inner member blade edge moves, the surface being provided with one or more orifices each surrounded and defined by edges not coplanar with the axis and cooperating with the or each inner member blade edge, and (c) means for holding a supply of material to be cut or shredding, having a lower outlet communicating with one or more upper orifices of the housing, whereby the material is fed into the one or more upper orifices and subsequently caused or allowed to fall as subdivided material from one or more lower orifices.

The blade is usually essentially straight and flat, for convenience in manufacture and sharpening. If it tapers, or if it is twisted, the angular extent of such taper or twist is generally small, since it is still essentially for use with outer member blade means edges which are not coplanar with the axis It is not practicable to give definitive figures for such twist or taper but normally plus/minus five degrees would be envisaged.

Three blades are preferred e.g. mutually at 1 20o. Two blades, or in the larger diameters four or more blades, are also possible.

Preferably the housing is generally in the form of a hollow cylinder with one or more (preferably two) elongate orifices extending along its length.

The housing may be shaped as two like cylindrical collars joined by two interconnections (usually integral with the collars) each interconnection having at least one edge at an angle to the longitudinal direction of the cylinder. These interconnections themselves may have parallel edges, and preferably the upper edges of these interconnections and mutually coplanar and the lower edges are also mutually coplanar.

A preferred form can thus be envisaged by starting from a hollow cylinder and providing (a) two cuts of different depths starting from opposite curved sides but occupying a common transvserse plane at right angles to the axis.

(b) a second identical pair of such cuts spaced along the cylinder and occupying a second transverse plane but reversed in depth.

whereby, opening to each curved side, there is both a shallower cut and deepr cut, the four cuts terminating (i) for those two cuts in each transverse plane, along parallel lines (ii) for those two cuts opening to each curved side, in a further common generally longitudinal plane non-parallel to the axis;and (c) cuts along the curved surface, two in each of said generally longitudinal common planes It will of course be appreciated that while this definition of the invention envisages notional cuts in a hollow cylinder, the commercial embodiment need not be formed by cutting in this shape. It can possibly be formed as a casting which is subsequently machined and worked. Alternatively, it could be fabricated from variously shaped metal components.

It is moreover possible to embody the invention in such a way as to avoid the use of one long cutting edge along an orifice in the housing. Thus, it is possible to use an-edge of a saw-toothed shape to define the orifices in the housing, in which case the material becomes subdivided at each angled portion of the saw tooth. Alternatively, two edges meeting at an angle, for example as defined by cuts in a hollow cylinder each at an angle and intersecting before they meet the axis, could be used. Possibly, the shape could be as defined by curved cuts, into the walls of a hollow cylinder and out again at a position spaced along the cylinder. Once again, refer ence to "cuts" should not be construed as limiting the method of construction but merely as a conventient mode of description of the shape of the article.

The invention will be further described with reference to the accompanying drawings, in which Figure 1 is a general perspective view of a three-bladed inner member within a cylindri,cal housing, and Figures 2, 3 and 4 are diagrammatic perspective views of different forms of housing for use with a blade as shown in Fig. 1. -- In Fig. 1 a inner member 1 is journalled for rotation around an axis 2 within a housing 3.

It is envisaged that the inner member will be turned manually e.g. by handle 4.

Inner member 1 possesses a first blade edge 5 e.g. of hard steel, second such edge 6, and third edge 7, all generally at right angles to the plane of the remainder of the blade, and each parallel and coplanar with axis 2. These edges therefore graze the inside of the cylindrical housing 3.

Cylindrical housing 3 e.g. of toughened steel possesses two identical orifices 8 and 8a, constituting a feed and a discharge orifice respectively. Feed orifice 8 has two vertical edges 9 and 10, both being at right angles to the axis of the cylinder and edge 9 being deeper than edge 10. The orifice 8 is further defined by generally longitudinal edges 11 and 1 2. Edges 5, 6 and 7 of inner member 1 cooperate progressively along edge 11 as the handle 4 is rotated in the direction of arrow A.

Of course, a motor drive could be provided.

Orifice 8a is similarly shaped to orifice 8 but in an opposite sense. It accordingly provides if necessary a cutting edge of the underside. Strap members 1 3 and 14 interconneict- ing the two generally cylindrical collars 1 5 and 1 6 are thereby generally defined by the orifices 7 and 8.

In use, the structure as shown is mounted in the lower discharge mouth of a hopper shown in chain-dotted lines, which can be made as a vacuum forming in stiff polymer' When this hopper is filled with vegetable garden refuse, rotation of the handle 4 causes the refuse which is usually generally elongate, to be cut between cutting edges such as 5 and 11 (or their counter-parts) and to fall as shredded or subdivided material by gravity through orifice 8a into a suitable pile or a suitable container beneath the hopper.

Fig. 2 shows an alternative shape for the housing. Instead of one long angled cutting edge a saw-toothed arrangement, with teeth 17, is provided. Effective cutting takes place on the angled edges 1 8 of the these teeth, the result being a subdivided material as be fore.

Fig. 3 shows a different type of housing 19, whose function will be generally clear from the above description.

Fig. 4 shows a yet different type of housing 20, having arcuate cuts in the cylindrical surface (or being cast to display such openings) which once again operates as the device shown in Fig. 1.

Claims (4)

1. Cutting or shredding equipment in which there are arranged for relative rotation about an axis: (a) an inner member with at least one inner member blade means having a substantially straight outer cutting or shearing edge, wherein when two or more of such inner member blade means are present their outer cutting or shearing edges, in any cross-section at right angles to the axis, are equidistant from the axis, said outer edge or edges being substantially coplanar with the axis, (b) an outer member with at least one outer member blade means having an inner cutting or shearing edge where when two or more such outer member blade means are present their inner cutting or shearing edges, at the said cross-section at right angles, are equidistant from the axis and effectively at the same distance from the axis as the cutting or shearing edges of the inner member blade means, said inner edge or edges not being coplanar with the axis, whereby relative rotation provides cutting or shear between the inner and outer blade edges.

2. Cutting or shredding equipment as claimed in claim 1 in which the inner member is a central rotary shaft or axis with two, three or more projecting blades substantially coplanar with the axis and with substantially straight and parallel outer edges.

3. Cutting or shredding equipment as claimed in claim 2 in which the outer member is a cylindrical coaxial housing in which blade means are defined at the edges of orifices in the housing.

4. Cutting or shredding equipment for use in subdivision of elongate vegetable garden refuse, comprising: (a) an inner rotary member having an axis of rotation and provided with at least one blade having an edge substantially parallel to and substantially coplanar with the axis, (b) a surrounding stationary housing with a coaxial inner curved surface over which the or each inner member blade edge moves, the surface being provided with one or more orifices each surrounded and defined by edges not coplanar with the axis and cooperating with the or each inner member blade edge, and (c) means for holding a supply of material to be cut or shredded, having a lower outlet communicating with one or more upper orifices of the housing, whereby the material is fed into the one or more upper orifices and subsequently caused or allowed to fall as subdivided material from one or more lower orifices.