GB2301097A - Anti-Bridging Chute Assembly - Google Patents

Abstract

Bridging caused by rock jammed in a chute (16, Fig 1) of a crusher (10) is freed by operation of a door member (34) inset in a wall of the chute and carried by a frame (32) movably mounted on a pair of toggle links (36, 38) and a locating link (40) under the action of a hydraulic cylinder (42). The toggle action produces plane parallel motion of the door (34) and also provides self-locking. Preferably, the chute has two tapered and two parallel side walls and doors are provided in both side walls. The doors can be opened together or separately. Preferably an additional safety lock such as tapered pins (44, Fig 3) are provided. Preferably the crusher is a rotary impact crusher.

Description

Anti-Bridging Chute Assembly' This invention relates to a chute assembly for use in supplying material to a processing apparatus.

The invention is particularly relevant to the feeding of quarried stone to a stone crusher but may also be useful in the feeding of other material of irregular size and shape.

In quarrying, it is conventional for stone to be loosened by blasting, which produces material of extremely irregular size and shape, typically ranging from a few centimetres up to about one metre in size.

This material is transported to a crushing plant in which the broken stone is tipped into a hopper from which it is fed via a chute to a crushing machine.

A problem which commonly occurs is that the stone jams to form a bridge within the chute, stopping the flow of material to the crusher. This problem has been found to be particularly acute with high volume impact crushers where it is necessary for the rotary crusher drum to be fully enclosed. Attempts have been made to deal with bridging in such crushing plants by the use of a pneumatically powered breaker inserted on an articulated boom from the top of the chute, but commonly this is not successful since the bridging occurs low down in the chute, and a number of dangerous practices have been resorted to in order to clear the bridging.

According to the present invention, there is provided a chute assembly having a peripheral wall of reducing cross-sectional area, in which part of the peripheral wall is formed by at least one door member which is moveable between a first position in which it forms a continuous surface with the remainder of the peripheral wall and a second position spaced outwardly from the first position.

In a preferred form of the invention, the peripheral wall is formed by converging front and rear walls and a pair of parallel side walls, there being two door members, one in each of the side walls.

The door member or each of the door members may be hinged at a top edge thereof. Preferably, however, each of the door members is arranged to move substantially parallel to its first position.

Each door member is suitably carried by a toggle mechanism arranged to provide mechanical locking in said first position. An additional safety lock mechanism may be provided to secure the door member in its first position.

Preferably, the toggle mechanism and the safety lock mechanism are hydraulically operated, most preferably from a common source of hydraulic power.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic side view of the crushing plant embodying the present invention; Fig. 2 is a schematic end view of the crushing plant of Fig. 1; Fig. 3 is a side view, partly in section, of a door assembly forming part of the crushing plant of Figs. 1 and 2; Fig. 4 is an end view, partly in section, of the door assembly of Fig. 3; Fig. 5 is a cross-section to an enlarged scale taken on the line C-C of Fig. 4; and Fig. 6 is a cross-section to an enlarged scale taken on the line D-D of Fig. 4.

Referring to Figs. 1 and 2, a crushing plant has an impact crusher comprising a substantially cylindrical housing 10 within which a drum carrying blades is rotated on a horizontal axle 12. Stone as quarried is tipped into a reception hopper 14 and passes by gravity to the crusher drum 10 via a chute assembly 16.

The chute assembly 16 comprises inwardly tapering front and rear walls 18 and 20 and parallel side walls 22 and 24. Each of the side walls 22 and 24 is partially formed by a door assembly 26 with an inner surface which normally lies flush with the remainder of the side wall but which can be moved outwardly of the chute 16 when desired by a distance of approximately 75mm.

One of the door assemblies 26 is illustrated in greater detail in Figs. 3 to 6. The door assembly comprises a welded steel framework 30 defining an aperture 31 within which is mounted a welded steel door member 32.

The inner faces of the framework and door member 32 are covered with replaceable steel wear plates 34 to form an inner surface which, in use, is flush with the inner surface of the remainder of the side wall 22 or 24 of the chute 16.

The door member 32 is mounted so as to be moveable outwardly of the chute in a parallel motion to a retracted position indicated in phantom. To achieve this, the door member 32 is mounted by means of upper and lower toggle linkages 36 and 38 and a lower link assembly 40. The toggle linkages 36 and 38 are interconnected by a push rod 41 and actuated by a common hydraulic cylinder 42 for movement between the closed toggle position shown in full in Fig. 4 and the open toggle position indicated by chain dashed lines. The use of toggle linkages to mount the door member 32 provides both parallel motion and a self-locking capacity in the closed position. As an additional safety measure, the assembly further comprises a safety lock in the form of tapered pins 44 mounted on the frame assembly 30 and engageable in a sleeve 46 on the door member 32 by the action of hydraulic cylinders 48.

As best seen in Fig. 5, each of the toggle linkages 36 and 38 comprises first toggle arms 50 and second toggle arms 52 rotatably interconnected by a centre hinge member 54. The first toggle arms 50 are rotatable by means of bearings 56 on a cylindrical member 58 which is fixed with respect to the framework 30, and the second toggle arms 52 are rotatable by means of bearings 60 on a cylindrical member 62 which is fixed with respect to the door member 32.

The link assembly 40, as best seen in Fig. 6, comprises radius arms 70 which are rotatable by means of bearings 72 on inner and outer cylindrical members 74 and 76 which are fixed with respect to the frame 30 and door member 32 respectively.

All the various rotational bearing faces are lubricated by pressure lubricant supplied via hoses 78.

Thus, if the supply of stone to the crusher drum housing 10 ceases because of bridging of stone within the chute 16, the doors 32 may be moved outwardly temporarily, which will normally be sufficient to dislodge the bridging stones and free the blockage.

The use of parallel motion linkages for this purpose is preferable since it permits an arrangement in which ingress of stone material into the door mechanism can be minimised.

It would normally be preferred to move both doors outwardly simultaneously and return them to the inner position simultaneously. It may, however, be useful to move one door at a time, or to cause the doors to move left and right in unison for two or three cycles.

Control systems for causing the hydraulic cylinders to produce movements of these types will be readily apparent.

The invention thus provides an arrangement which enables bridging of stone in feed chutes to be cleared without the need for any free opening to be formed in the chute or in a crusher drum contiguous with it, which is a considerable aid to safety. Equally, there is no necessity for any operator to insert any implement into the path of stone transport. The doors can be actuated remotely by an operator in a control cabin, or automatically.

Although the foregoing embodiment describes the use of two doors each mounted for parallel motion, other forms may be useful within the scope of the invention. There may be a single door, and the or each door may be moveable in a non-parallel form, such as by movement about a hinge at its top edge.

Other modifications and improvements may be made within the scope of the present invention.

Claims (9)

1. A chute assembly having a peripheral wall of reducing cross-sectional area, in which part of the peripheral wall is formed by at least one door member which is moveable between a first position in which it forms a continuous surface with the remainder of the peripheral wall and a second position spaced outwardly from the first position.

2. A chute assembly according to claim 1, in which the peripheral wall is formed by converging front and rear walls and a pair of parallel side walls, there being two door members, one in each of the side walls.

3. A chute assembly according to claim 1 or claim 2, in which the or each door member is arranged to move substantially parallel to its first position.

4. A chute assembly according to claim 3, in which the or each door member is carried by a toggle mechanism arranged to provide mechanical locking in said first position.

5. A chute assembly according to claim 4, in which an additional safety lock mechanism is provided to secure the door member in its first position.

6. A chute assembly according to claim 5, in which the toggle mechanism and the safety lock mechanism are hydraulically operated from a common source of hydraulic power.

7. A chute assembly according to any of claims 3 to 6, in which the toggle mechanism for the or each door comprises a pair of spaced-apart toggle arms and a locating link, each of the toggle arms comprising inner and outer links pivotally connected together, the inner link pivoted to the door and the outer link pivoted to a frame of the chute, and a common hydraulic actuator acting on both toggle arms.

8. A chute assembly according to claim 7, in which the toggle arms and the locating link have pivot bearings supplied with a pressurised lubricant from a common lubricant source.

9. A chute assembly substantially as herein described with reference to and as illustrated in the drawings.