EP0389487A1

EP0389487A1 - Hammermills

Info

Publication number: EP0389487A1
Application number: EP19880908287
Authority: EP
Inventors: Edward Aneurin Evans
Original assignee: METPRO MACHINERY Ltd
Current assignee: METPRO MACHINERY Ltd
Priority date: 1987-09-22
Filing date: 1988-09-22
Publication date: 1990-10-03
Also published as: HU205280B; WO1989002784A1; GB8722260D0; HU885493D0; GB2209962B; GB8819336D0; GB2209962A

Abstract

Broyeur à marteaux du type à découpage dans lequel on peut découper en petites pièces de gros objets métalliques tels que des automobiles, comportant une grille (20) entourant un rotor (14) doté d'une série de marteaux dont les bouts suivent une trajectoire circulaire autour du rotor. On peut faire varier la taille des orifices de décharge (22) afin de permettre le passage de pièces découpées plus grosses ou démesurées, par mouvement pivotant d'un dispositif à ''clé'' (24) et/ou par l'ouverture d'une porte d'éjection (28).Cutting-type hammer mill in which large metal objects such as automobiles can be cut into small pieces, comprising a grid (20) surrounding a rotor (14) provided with a series of hammers whose ends follow a circular path around the rotor. The size of the discharge orifices (22) can be varied in order to allow the passage of larger or disproportionate cut pieces, by pivoting movement of a "key" device (24) and / or by the opening of 'an ejection door (28).

Description

Hammermills

Ihis invention relates to hammermills, and more particularly to shredder type hammermills in which large metallic objects, such as automobiles, can be shredded into small pieces.

Shredder type hammermills are well known (examples of such machines being described in U.S. Patents 3489078 and 3545690). In operation of such a hammermill, a metallic object fed into the hammermill is subjected to impact by a series of heavy hammers carried on a shaft which is rotated at high speed, the tips of the hammers following a circular path (known as the hammer circle) . Ihis impact within the hammer circle causes relatively small pieces to be torn out of the metallic object. A series of grate bars having discharge openings extend around the hammer circle so that pieces which are small enough fall through the openings can be discharged from the machine; larger pieces are struck repeatedly until they are sufficiently reduced in size.

Cne disadvantage of such hammermills is that pieces of metal which are heavy, thick and tough will take more time to be broken into small enough pieces to fall through the discharge openings. The extra time taken within the hammermill to break up the metal pieces results in extra wear on all the internal parts, which means that parts of the . machine have to be maintained and replaced more frequently.

The present invention seeks to provide an improved hammmermill, in which the above disadvantages are at least alleviated. According to the present invention, there is provided a hammermill for shredding bulky metallic objects, which comprises an enclosure having therein a rotatably driven shaft having mounted thereon a series of hammers for shredding said objects within the hammer circle defined by the circumferential periphery of said hammers, and a grating which extends around the shaft and hammer circle and has a series of discharge openings for discharge of shredded pieces from within said enclosure, characterised in that means are provided for varying the dimensions of the discharge openings in said grating so as to allow the discharge of shredded pieces of varying size or quantity from said hammer circle.

Preferably the grating includes an ejection door which is movable between an open position and a closed position. The ejection door may be hinged along one edge so that it can open freely upon impact of a (large) piece of material, such that the latter can pass through the aperture defined by the open door even when it is too large to pass through other discharge openings of the grating. Should the door not freely hinge open, however, it can be opened by externally applied force and held open until the large piece is thrown clear by the forces generated within the hammermill by the driven shaft. he ejection door may itself have discharge openings therethrough.

Ihe means for varying the dimensions of the discharge openings preferably comprises at least one apertured insert for the grating, the insert being movable from a first, locked position in which the insert comprises part of the grating and in which the apertures in the insert comprise discharge openings which are of relatively small dimensions, to a second, unlαcked position in which the insert is remote from the grating and the dimensions of the discharge openings are accordingly relatively large. Ihe insert is preferably hinged at or adjacent one edge about a hinge line which is typically parallel to the shaft. Such an insert (also referred to herein as a "key" or "key" device) , may be movable from the locked to the unlocked position and vice versa by mechanical, hydraulic or other suitable means.

Ihe invention will now be described further, by way of example only, with reference to and as illustrated in the accompanying drawings, in which:

Figure 1 is a schematic cross sectional view of a shredder type hammermill in accordance with the invention;

Figure 2 is a view of part of the key device in the direction of arrow A;

Figure 3 is a view of the grating as it would appear from the interior of the hammer circle; and

Figures 4a, 4b and 4c are perspective views of, respectively, exemplary grating, key device and combination of grating and key device, for use in the hammermill according to the invention.

Referring to the drawings, a shredder type hammermill 10 comprises a feed (not shown) which is arranged to deliver metallic objects into the hammer circle (which will be described below) . A cutter bar (not shown) may be located at the entry 12 into the hammermill, in order to absorb the forces generated as the objects are shredded. A barrel rotor 14 is mounted on and driven by a shaft 16; the rotor carries a plurality of hammers 18 (typically arranged in rows on the rotor) at the periphery of the rotor, rotation of the latter defining the circumferential extent of the hammer circle. The rows of hammers 18 rotate and impact upon the object or objects fed into the hammer circle, thereby chopping slugs of material therefrom in the same way as described and illustrated in U.S. Patents 3545690 and 3489078. A grating 20 having discharge openings 22 extends around the rotor 14 to facilitate removal of pieces of material from the hammer circle. Pieces of material which are torn from the object or objects impacted by the hammers in the hammer circle are dragged around between the perimeter of the rotor 14 and the grating 20 until they are sufficiently reduced in size to fall through the discharge openings 22. If the object fed into the hammer circle contains heavy or thick metal, the time required to cause breakdown into small enough pieces can be fairly lengthy, which increases wear and tear on the internal parts of the hammermill.

According to a first aspect of the invention, therefore, the key device (or insert) 24 is provided which serves to vary the dimensions of the discharge openings 22. hen the dimensions of the latter openings are relatively large, larger pieces of material are allowed to fall therethrough, thereby reducing wear on the internal parts of the shredder and allowing quicker ejection of the metal, albeit in larger particles. Ihe key device 24 comprises a plurality of cross-shaped members 26 (see Figures 2 and 4b) which locate in discharge openings 22, thereby reducing the effective size of the openings as can be seen more clearly in B^'igure 3. he cross-shaped members are mounted on an arcuate member, pivotally connected to the hammermill body at point X and is able to move from a first, locked position (see Figure 4c) in which the key device cooperates with art of the grating 20 to form small discharge openings defined by the cross-shaped members 26, to a second, unlocked position in which the key device is remote from the grating and the discharge openings have their maximum size as can be clearly seen in Figures- 1 and 4a. The key device is typically pivoted either by mechanical or hydraulic actuation means. A further mechanism is provided to facilitate the removal of pieces of material which are too large to fall through discharge openings 22 even when the latter have their maximum size. Ihe mechanism comprises an ejection door 28 located in the roof of the shredder; the door 28 is hinged at Y, and is arranged to open freely and automatically upon impact of a sufficiently large piece of material, thereby allowing the oversize piece of material to be ejected from the hammermill. Should the door not freely hinge open, however, it can be opened by operating a lever (not shown) at hinge point Y, and then held open until the piece is thrown clear by the forces generated within the hammermill by the rotor. tøhen the key device is in the locked position and the discharge openings have their smallest dimensions, there is the possibility that the operator may feed metal into the hammermill at a faster rate than it can be broken up into small enough pieces. In such cases the metal will build up within the shredder and will force open the ejection door and be ejected before serious congestion occurs in the hammermill. Congestion within the hammermill causes extra loading on the rotor and in turn on the main driving gear which can, in a conventional hammermill, cause the driving gear to stall out completely. If this occurs the hammermill cannot be re-started before all the metal is manually cleared out from within the shredder. Clearly, therefore, the provision of the ejection door in the embodiment according to the invention enables the hammermill to function more efficiently with minimised chances of breakdown.

Ihe hammermill according to the invention is therefore more flexible and effective than known hammermills, and is less susceptible to excessive and damaging wear.

Claims

Clai s :

1. A hammermill for shredding bulky metallic objects, which comprises an enclosure having therein a rotatably driven shaft having mounted thereon a series of hammers for shredding said objects within the hammer circle defined by the circumferential periphery of said hammers, and a grating which extends around the shaft and hammer circle and has a series of discharge openings for discharge of shredded fragments from within said enclosure, characterised in that means are provided for varying the dimensions of the discharge openings in said grating so as to allow the discharge of shredded fragments of varying size or quantity from said hammer circle.

2. A hammermill according to claim 1, wherein the grating includes an ejection door which is movable between an open position and a closed position and in which the aperture of the open ejection door is large enough to allow the passage therethrough of fragments which are too large to pass through the other discharge openings of the grating.

3. A hammermill according to claim 2, wherein the ejection door is arranged to be opened by an externally applied force and/or is mounted such that it can be opened by the impact thereon of a large fragment of metal or by a large quantity of fragments of metal.

4. A hammermill according to any claim 2 or 3, wherein the ejection door is hinged at one edge thereof and is preferably positioned adjacent the upper part of the hammer circle above the shaft.

5. A hammermill according to any of claims 2 to 4, wherein the ejection door includes discharge openings therethrough,

6. A hammermill according to any preceding claim, wherein said means for varying the dimensions of the discharge openings comprises at least one apertured insert for said grating, said insert being movable from a first, locked position in which the insert comprises part of the grating and in which the apertures in said insert comprise discharge openings which are of relatively small dimensions, to a second, unlocked position in which the insert is remote from the grating and the dimensions of said discharge openings are accordingly relatively large.

7. A hammermill according to claim 6, wherein said insert is hinged at or adjacent one edge thereof about a line substantially parallel to said shaft and is preferably located substantially diametrically opposite the zone at which the object to be shredded enters the hammer circle.

8. A hammermill according to claim 6 or 7, wherein said discharge openings, between the zone in which the object to be shredded enters the hammer circle and the region where said insert can be incorporated in the grating, are of relatively small dimensions, and the insert comprises a plurality of prong members, each of which members is movable into and out of one of said relatively larger discharge openings.

9. A hammermill according to claim 8, wherein said relatively larger discharge openings are of rectangular cross section and said prong members are of cross-shaped cross section.

10. A hammermill according to claim 9, wherein the discharge openings comprising said apertures in said insert are of similar size to said discharge openings of relatively small dimensions.