Hammer crusher

Abstract

 A crushing plant, comprising a cage (2) containing a hammer rotor (3) and presenting a loading mouth (22) connected to a system for the supply of loose material (5) to be crushed, said system comprising a service corridor provided with an arrival hopper for the material to be crushed, and means for advancing the material along the corridor with stepwise movement, the downstream end of said corridor being upperly open, and within it there being slidingly positioned a compactor member (8) arranged to vary its level, in synchronism with the stepwise movement, between a raised rest position in which it guides the material lying within the corridor, and a lowered working position in which it presses the temporarily stationary material against the base of the corridor, before being thrust into the cage containing the rotor.

Description

[0001] This invention relates to crushing plants commonly known as hammer crushers or mills, a typical use of which is in crushing ferrous and non-ferrous metal materials originating from the recovery of materials sent for scrap, and which are usually intended to be converted into raw material by melting and conditioning in a blast furnace.

[0002] Said materials can be in the form of parallelepiped pieces obtained for example by pressing automobile bodies, or variously shaped pieces originating from the dismantling of scrapped articles.

[0003] To reduce such recovered materials to small pieces, crushing plants are known comprising essentially a robust metal cage within which a rotor rotates at high speed.

[0004] Hinged to its periphery, the rotor carries a series of slabs, commonly known as hammers, which swing about a non-barycentric axis and are maintained facing outwards from the rotor by the centrifugal forces in play.

[0005] The cage presents a lateral loading mouth communicating with a service channel or corridor with which there is associated a pusher where the material to be crushed is amassed in the loose state.

[0006] Within said channel there are also positioned feed means, usually in the form of a pusher driven with reciprocating rectilinear movement to introduce into the cage the material to be crushed, which originates from the hopper.

[0007] The material is struck by the hammers which, either alone or in combination with at least one anvil fixed to the plant frame, reduce it into pieces of relatively small dimensions which pass through the meshes of the cage and collect on the outside of it.

[0008] A problem which arises with such crushing plants, in particular when the material to be crushed is mainly in the form of loose pieces of various shapes and sizes originating from the sectioning of articles to be scrapped, derives from the fact that the mass of loose material which is gradually introduced into the cage presents a particularly non-homogeneous distribution, i.e. it presents relatively dense regions in which the pieces have mutually copenetrated, and regions in which most of the space is empty rather than full.

[0009] Said sudden random variations in the compactness of the mass result in sudden variations in the resistance encountered by the rotor, the operation of which becomes intermittent in the sense that periods in which the rotor operates practically at full capacity are followed by periods in which it rotates practically empty.

[0010] Essentially, this type of operation leads to impacts and vibration which can be damaging not only for the rotor and cage, but also for the rotor drive unit.

[0011] The main object of the present invention is to provide means able to substantially eliminate the aforesaid problem.

[0012] A further object of the invention is to attain said object within the context of a simple, rational, reliable and durable construction.

[0013] Said objects are attained by a crushing plant presenting the characteristics indicated in the claims.

[0014] It comprises a robust cage containing a hammer rotor and presenting a loading mouth communicating with a service corridor provided with a hopper for supplying the material to be crushed, and means for advancing the material along the corridor with stepwise movement.

[0015] According to the invention, the downstream end of said corridor is upperly open, within it there being slidingly positioned a compactor member arranged to vary its level, in synchronism with the stepwise movement of the material to be crushed, between a raised rest position in which it guides the material being advanced, and a lowered working position in which it presses the temporarily stationary material against the base of the corridor.

[0016] All the objects of the invention are attained by the aforesaid solution.

[0017] In this respect, the action of said member, which will be described in detail hereinafter, compacts the mass of material directed towards the rotor is made much more homogeneous, so that its operation is much more regular, i.e. without the aforesaid inconvenient fluctuations, as has been demonstrated by specific tests conducted with a pilot plant constructed in accordance with the invention.

[0018] The constructional characteristics and merits of the invention will be apparent from the ensuing detailed description given with reference to the figures of the accompanying drawings, which illustrate a particular preferred embodiment thereof by way of non-limiting example.

[0019] Figure 1 is a schematic sectional side elevation of a plant according to the invention, the compactor member being shown in its raised position.

[0020] Figure 2 is a view totally similar to the preceding, but with the compactor member shown in its lowered position

[0021] Figure 3 is the section III-III of Figure 2.

[0022] Said figures, and in particular Figure 1, show a box casing 1 containing a robust stationary cage 2.

[0023] The cage 2 comprises a series of vertically lying curved flat elements 20, known as ribs, which are individually shaped as a sector of a circular ring, and are open towards the upper front region of the plant to form the loading mouth 22 for said cage 2.

[0024] The ribs 20 are joined together by the beams indicated by 21, which in their turn are fixed to the side walls 10 of the casing 1.

[0025] A rotor 3 comprising hammers 4, of known type, is rotatably mounted within the cage 2.

[0026] At least one of said beams 21 is more robust than the others and acts as the anvil for said hammers 4.

[0027] As can be seen, in front of the mouth 22 of the cage 2 there is an advancement corridor 110 for the material 5 to be crushed, this being loaded loosely into a hopper 111 the base of which communicates with said corridor 110.

[0028] Within the upstream end of the corridor 110 there is positioned a box-shaped pusher 6 for pushing the material 5 towards the mouth 22 of the cage 2 under the control of a hydraulic cylinder-piston unit 7.

[0029] According to the invention, as can be seen in Figure 3, the downstream end of the corridor 110 is upperly open, and within it there is housed a movable profiled member 8 provided to compact the material 5 prior to its introduction into the cage 2.

[0030] In side view (Figures 1 and 2) said member 8 has substantially the shape of a bent wall the convexity of which faces the material 5 to be crushed.

[0031] In particular, it comprises two vertically lying arched lateral plates 80 which are positioned against the side walls 10 of the casing 1 (see Figure 3), and are connected together by two curved transverse walls 81 and 82, which provide said bent profile.

[0032] The wall 81 faces the base of the corridor 110, to form its respective roof portion, and the wall 82 faces the upstream region of the casing 1, to form together with the preceding (Figures 1 and 2) the rear part of the hopper 111.

[0033] The movable member 8 is hinged on a transverse horizontal axis of rotation 83 positioned along the upper side of the loading mouth 22 of the cage 2, and is controlled by a hydraulic cylinder-piston unit 99, the body of which is hinged at 84 to a cross-member 85, and the rod of which is pivoted at 86 to the pointed part of the said member 8.

[0034] It should be noted that the hydraulic circuit serving the cylinder-piston unit 99 is provided with a suitable overpressure valve.

[0035] The hydraulic circuits serving the cylinder-piston units 7 and 99 are connected together operationally, in such a manner that said cylinder-piston units 7 and 99 act in synchronism in the following manner.

[0036] When, after a stage involving the crushing of the material 5 present at the downstream end of the corridor 110, the member 8 is about to attain its raised rest position of Figure 1, the pusher 6 receives the enabling command to advance in order to transfer into the cage 2 the material previously crushed, and to position in its place new loose material to be crushed.

[0037] After this the pusher 6 withdraws and, before it reaches its end-of-travel position, the member 8 is lowered as shown in Figure 2, in order to compact said new material, after which said stages of the cycle are repeated identically.

Claims

1. A crushing plant, comprising a cage (2) containing a hammer rotor (3) and presenting a loading mouth (22) connected to a system for the supply of loose material (5) to be crushed, said system comprising a service corridor provided with an arrival hopper for the material to be crushed, and means for advancing the material along the corridor with stepwise movement, characterised in that the downstream end of said corridor is upperly open, within it there being slidingly positioned a compactor member (8) arranged to vary its level, in synchronism with the stepwise movement, between a raised rest position in which it guides the material lying within the corridor, and a lowered working position in which it presses the temporarily stationary material against the base of the corridor, before being thrust into the cage containing the rotor.

2. A plant as claimed in claim 1, characterised in that said movable member comprises a profiled wall which at one end is hinged along the upper side of the cage loading mouth, and is connected to the frame of the plant by at least one hydraulic cylinder-piston unit.

3. A plant as claimed in claim 2, characterised in that said profiled wall has an arched lateral profile with its convexity facing the base of the corridor.

4. A plant as claimed in claim 2, characterised in that said at least one hydraulic cylinder-piston unit is associated with an overpressure valve.

5. A plant as claimed in claim 2, characterised in that said profiled wall presents, in a position opposite that at which it is hinged to the frame, an arched portion which is bent towards the profiled wall, has its concavity facing that of said profiled wall, and forms the respective transverse part of the hopper.

Drawing