Hammer-type crushing plant

Abstract

 A crushing plant, comprising a cage containing a motor-driven hammer rotor (3) and presenting a loading mouth (22) for the material to be crushed, there being associated with said mouth a movable closure member (8) able to be positioned in a rest position in which it lies outside the path followed by the material, or a working position in which it intercepts said path.

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 scrap such as automobile bodies.

[0002] 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.

[0003] 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.

[0004] For the entry of the material to be crushed, the cage presents a lateral mouth with which introduction means, such as a thrust plate, are associated to advance the mass of loose material.

[0005] 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.

[0006] Such crushing plants, which are of particularly high power, operate well when they have attained their working speed, however a critical or weak point is represented by their start-up, during which the rotor and the surrounding elements can suffer irreparable damage if material to be crushed is already present within the cage.

[0007] For this reason, the operator must verify that the cage is empty before halting the plant.

[0008] However it can happen, as has already happened, that during plant stoppage a part of the material amassed in the loose state in front of the cage entry mouth falls untimely into it, with the stated consequences.

[0009] The main object of the present invention is to provide means able to eliminate the aforesaid problem.

[0010] A further object of the invention is to attain said object within the context of a simple, rational, reliable and durable construction.

[0011] Said objects are attained by a crushing plant presenting the characteristics indicated in the claims.

[0012] To attain said objects, the plant of the invention presents a movable blocking or closure member, which is positioned at the entry mouth of the rotor cage and is arranged to slide between a rest position in which it is situated outside the path followed by the material directed towards the cage, and a working position in which it intercepts said path.

[0013] All the objects of the invention are attained by the aforesaid solution.

[0014] In this respect, when said blocking member, described in detail hereinafter, is disposed in said working position, it prevents any material present in front of the mouth of the cage from falling untimely into it.

[0015] Essentially, once the member has been positioned in said working position, before halting the plant the rotor must obviously be rotated until all the material still present in the cage has been completely depleted, the subsequent start-up of the plant then not involving any risk of breakage of the rotor and/or the surrounding parts as the blocking member prevents any untimely fall of material into the cage.

[0016] The constructional characteristics and merits of the invention will be apparent from the ensuing detailed description given with reference to the accompanying figures which illustrate a particular preferred embodiment thereof by way of non-limiting example.

[0017] Figure 1 is a schematic sectional side elevation of a plant according to the invention.

[0018] Figure 2 is the section II-II of Figure 1.

[0019] Said figures, and in particular Figure 1, show a box casing 1 containing a robust stationary cage 2.

[0020] The cage 2 comprises a series of vertically lying equidistant 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.

[0021] 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.

[0022] A rotor 3 comprising hammers 4, of known type, is rotatably mounted within the cage 2.

[0023] At least one of said beams 21 is more robust than the others and acts as the anvil for said hammers 4.

[0024] 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 the central part of the roof of said corridor 110.

[0025] Within the upstream end of the corridor 110 there is positioned a box-shaped pusher 6 for serving the material 5 to the mouth 22 of the cage 2.

[0026] Said pusher 6 is slidingly driven to and fro by a hydraulic cylinder-piston unit 7 hinged to the base of the corridor 110.

[0027] According to the invention, and as can be seen in Figure 2, at the loading mouth 22 of the cage 2 there is provided a movable blocking member provided to prevent further feed of material 5 into the cage 2 at the moment of stoppage of the rotor 3.

[0028] In the illustrated example said member comprises a robust horizontal cylindrical bar 8 positioned transversely to the corridor 110 and having a diameter substantially equal to one third of the height of the corridor 110 (see Figure 1).

[0029] The bar 8 is supported by a robust sleeve 80 fixed onto the outside of the left side wall 10 of the casing 1 (see Figure 2)), and is slidingly driven by a hydraulic cylinder-piston unit 88 fixed to the same side wall 10.

[0030] When the rotor 3 rotates, the bar 8 is extracted from the corridor 110, and when the plant is to be halted the bar 8 is inserted into the corridor as shown in Figure 2.

[0031] The hydraulic circuit serving the cylinder-piston unit 88 is controlled by the personnel operating the plant.

[0032] Alternatively, the circuit serving the cylinder-piston unit 88 could be connected to the general control and regulating system for the plant such that:

• when the command is given to halt the plant, the rotor 3 stops after the bar 8 has been made to advance, with a delay sufficient to enable the rotor 3 to dispose of all the material 5 present in the cage 2, and
• when the command is given to start the plant, the bar 8 is retracted with a certain delay to enable the rotor 3 to attain its working speed.

[0033] Various variants are possible for said blocking member.

[0034] For example, it can assume the form of a horizontally extending elongate plate positioned perpendicular to the corridor 110 and driven to slide parallel to itself as stated.

[0035] Alternatively, said blocking member can have the form of a comb with two or more horizontal teeth.

[0036] In addition, as a variant, the outward and return travel of the blocking member can be provided by a rack-pinion linkage, the pinion being connected to an electric or hydraulic motor by way of a clutch unit, and the rack being associated with that part of the member situated outside the corridor 110.

[0037] The blocking member can also be formed in the manner of a guillotine arranged to slide within a matching slot provided in the roof or in the floor of the corridor 110, between a rest position in which its active edge is coplanar with said slot, and a working position in which said edge extends beyond said slot.

[0038] The guillotine can be operated by means similar to those heretofore described, or by a cam system with an associated device for limiting the pressing force.

Claims

1. A crushing plant, comprising a cage containing a motor-driven hammer rotor (3) and presenting a loading mouth (22) for the material to be crushed, characterised in that a movable closure member (8) is associated with said mouth, said member being able to be positioned in a rest position in which it lies outside the path followed by the material, or a working position in which it intercepts said path.

2. A plant as claimed in claim 1, characterised in that said movable member consists of a horizontal bar arranged to slide parallel to itself.

3. A plant as claimed in claim 1, characterised in that said movable member consists of a horizontally extending elongate flat body arranged to slide parallel to itself.

4. A plant as claimed in claim 1, characterised in that said movable member is shaped as a comb having at least two teeth, and arranged to slide parallel to said teeth.

5. A plant as claimed in claim 1, characterised in that said movable member is shaped as a guillotine associated with the upper or lower edge of the loading mouth of the cage.

6. A plant as claimed in claim 1, characterised in that said movable member is driven by a hydraulic cylinder-piston unit.

7. A plant as claimed in claim 6, characterised in that said hydraulic cylinder-piston unit is provided with pressure limiting valve means.

8. A plant as claimed in claim 1, characterised in that said movable member is driven by a rack with which a motorized pinion engages.

9. A plant as claimed in claim 8, characterised in that a clutch unit is interposed between said pinion and the respective motor.

10. A plant as claimed in claim 1, characterised in that the operating means for said movable member are operationally connected to the general control and regulating system of the plant so that the stop and start commands to the rotor result respectively in the activation of the blocking member in advance of the stoppage of the rotor, and the deactivation of the blocking member subsequent to the starting of the rotor.

Drawing