GB2186811A

GB2186811A - Mobile mixing apparatus and method

Info

Publication number: GB2186811A
Application number: GB08703861A
Authority: GB
Inventors: Peter John Renwick
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-20
Filing date: 1987-02-19
Publication date: 1987-08-26
Also published as: GB2186811B; GB8604154D0; GB8703861D0

Abstract

Apparatus for mixing material, e.g. concrete or animal feedstuffs, comprises a rotatable open-ended drum (1) mounted on the three point linkage (5) of a tractor (4). One or more helical vanes are provided around the inside surface of the drum. Material is loaded by setting the drum with its axis horizontal, and thrusting the drum into a pile (6) of aggregate while rotating the drum in a direction such as to move materials towards the rear of the drum. The drum is then tilted upwardly and rotated in the same direction to effect mixing. Unloading of the drum is effected by reversing the direction of rotation of the drum. <IMAGE>

Description

SPECIFICATION Mixing apparatus and method The present invention relates to apparatus for, and a method of, mixing material, and relates in particular, but not exclusively, to apparatus for and a method of mixing concrete. The invention is also applicable to the mixing of other materials, for example animal feed stuffs.

Known concrete mixers typically mix sand, agregate, cement and water, by rotation of the materials within an open-ended drum. Agitation during mixing is improved by the attachment of baffles to the inside of the drum. In large, truck-mounted, concrete mixers, the baffles are provided by one or more vanes formed in the shape of a helix or Archimedean screw, and provide means for unloading the mixer by reversing the direction of rotation of the drum after mixing. Such mixers are conventionally loaded from an overhead hopper in a central depot.

Smaller versions of such a chassis mounted mixer are provided with a separate scoop or loading shovel, which upon being raised lifts the mixed agregate and then discharges it into the mixing drum. A still smaller tractormounted form of concrete mixer is also available, but the attachment of such a self-loading shovel to a small tractor-mounted mixer is costly, and renders the whole apparatus cumbersome and less manoeuverable. Small tractor-mounted mixers are therefore conventionally loaded manually by shovel. A final, smallest, form of concrete mixer consists of a manually operated, or motor driven, drum on a portable frame which is pushed to a required location. In these machines loading is again by manual shovelling, and unloading is achieved by tipping the entire drum to discharge the material by gravity.

It is an object of the present invention to provide a mixing apparatus having improved means for loading the apparatus, especially suitable for small mixing apparatus such as smaller concrete mixers.

According to the present invention there is provided mixing apparatus comprising a rotatable, open-ended drum having within the drum conveying means for moving material along the drum, means for rotating the drum in a first direction tending to move the material away from the open end of the drum for loading and mixing, and in a second direction intending to move the material towards the open end of the drum for unloading, and means for mounting the drum on a mobile frame and for varying the inclination of the drum between an upwardly inclined position for mixing, and a position at or closer to the horizontal for loading the material into the drum by advancing the open end of the drum into the material to be loaded and rotating the drum in the said first direction.

In preferred forms, the said conveying means comprises at least one vane inside the drum inclined to the drum axis and arranged to move material towards one or other end of the drum depending on the direction of rotation of the drum.

Although the drum may be used for loading while still slightly inclined to the horizontal in some arrangements, it is preferred that the mounting means is adapted to allow the drum to be positioned, during loading, with its axis substantially horizontal. Also, although in some circumstances the drum may be raised above the ground during loading, for example when loading from a bunker, it is preferred that the mounting means is adapted to allow the drum to be positioned, during loading, with the underside of the open end of the drum in contact with or closely adjacent to the ground.

The drum may be of a number of different shapes, for example including a truncated cone, but it is preferred that the drum is a right-circular cylindrical drum, since this allows the entire underside of the drum to rest on the ground while the drum is being pushed into a pile of material to be loaded.

The or each vane may take a number of forms, including a number of discrete inclined paddles along the length of the drum, but it is preferred that the or each vane comprises a continuous helical flight projecting inwardly from the side wall of the drum.

In accordance with a preferred form of the invention, there may be provided mixing apparatus comprising a mobile frame, a rotatable, open-ended drum having at least one internal vane inclined to the drum axis and arranged to move material towards one or other end of the drum depending upon the direction of rotation of the drum, means for rotating the drum in a first direction tending to move the material away from the open end of the drum for loading and mixing, and in a second direction tending to move the material towards the open end of the drum for unloading, and means for varying the inclination of the drum between an upwardly inclined position for mixing, and a loading position in which the drum has its axis substantially horizontal with the underside of the open end of the drum in contact with or closely adjacent to the ground, for loading material into the drum by advancing the open end of the drum into the material to be loaded and rotating the drum.

There is also provided in accordance with the invention a method of mixing material comprising the steps of advancing into a pile of material an open-ended drum having within the drum conveying means for moving material along the drum, rotating the drum in a direction such as to convey material into the drum from the pile, rotating the drum in the same direction as the direction for loading the material, so as to effect mixing within the drum, and rotating the drum in the reverse direction to the loading and mixing direction so as to effect discharge of material from the drum.

Preferably the method includes the step of moving material along the drum by the effect of at least one vane positioned inside the drum and inclined to the drum axis.

Preferably the method includes the step of changing the direction of the drum axis after the loading step, so as to position the drum with the open end upwardly inclined relative to the position for loading.

Preferably the method includes the step of setting the axis of the drum to be substantially horizontal during the loading step.

Also preferably the method includes the step of positioning the drum with the underside of the open end of the drum in contact with or closely adjacent to the ground during loading.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagrammatic rear view of the mixing apparatus embodying the invention attached to the rear of a tractor, the mixing apparatus being positioned in a lowered position; Figure 2 is a diagrammatic side view of the mixing apparatus of Figure 1, when in the lowered position; Figure 3 is a side view of the apparatus of Figure 2, when in the raised position; and Figure 4 is a rear perspective view of a modified mixing apparatus embodying the invention having two conveying vanes.

With reference to Figures 1 to 3, a mixing apparatus embodying the invention comprises a mixing drum 1 mounted on a shaft 2 which is itself supported by a frame 3 for mounting the drum on the three point linkage 5 of a tractor 4.

The drum 1 has an internal vane 7 comprising a single, continuous, helical flight projecting inwardly into the drum from the side wall of the drum and extending along the length of the drum in the manner of an Archimedian screw. The drum 1 is rotatable in both directions by means of a reversible hydraulic motor.

In use, the drum 11 is first lowered to a horizontal position with the underside of the drum touching the ground, by means of the three point linkage 5, as shown in Figures 1 and 2. The tractor 4 is then reversed and the open end of the drum 1 is thrust into a heap of mixed agregate 6 and at the same time the drum is rotated in the direction required to move material away from the mouth of the drum towards the closed end. Agregate is drawn into the mixing drum 1 by the action of the helical flight 7.

The drum is then raised and tilted, to the position shown in Figure 3, such that the open end of the drum is higher than the closed end. Water and cement are then added in the correct quantities. The agregate, water and cement are then mixed by further rotation of the drum 1 in the same direction as the loading direction. Mixing is achieved by the flow of material towards the closed end of the drum under the influence of the helical flight 7. The material is lifted at the rear by rotation of the drum and cascades back down again at the closed end of the drum.

Unloading is achieved by reversing the direction of rotation of the drum, allowing the helical flight 7 to move the material to and out of the open mouth of the mixing drum, as shown in Figure 3. This can be achieved either in the inclined position of Figure 3, or, if convenient, by lowering the inclination of the drum.

The raising and tilting of the drum is effected by the geometry of the tractor's three point linkage. This position is ideal for both mixing and unloading the final mixed concrete 8, as shown in Figure 3. Conveniently a means for reversing the direction of rotation of the drum may be provided between the drum and the source of rotational drive provided by the tractor.

In Figure 4 there is shown a modification of the drum shown in Figure 1. Two continuous helical vanes 7 are provided on the inside of the drum. Each vane extends right to the outer end of the drum, and is curved at its outer end, to assist in loading material when the drum is thrust into a pile of material.

The present invention, at least in the preferred embodiment which has been described, allows a single drum to put into effect three different functions, namely the scooping and loading of material into the drum, the mixing of the material at a convenient inclined angle of the axis of the drum, and the discharge of material from the drum by a reverse direction of rotation of the drum.

It is particularly to be appreciated that the invention may be used for mixing any materials other than concrete, for example, animal feed stuffs.

Another advantage is that the mixed, but not unloaded, concrete may conveniently be moved to a required location by the tractor, before unloading.

Claims

1. Mixing apparatus comprising a rotatable, open-ended drum having within the drum conveying means for moving material along the drum, means for rotating the drum in a first direction tending to move the material away from the open end of the drum for loading and mixing, and in a second direction intending to move the material towards the open end of the drum for unloading, and means for mounting the drum on a mobile frame and for varying the inclination of the drum between an upwardly inclined position for mixing, and a position at or closer to the horizontal for loading the material into the drum by advancing the open end of the drum into the material to be loaded and rotating the drum in the said first direction.

2. Apparatus according to claim 1 in which the said conveying means comprises at least one vane inside the drum inclined to the drum axis and arranged to move material towards one or other end of the drum depending on the direction of rotation of the drum.

3. Apparatus according to claim 2 in which the or each vane comprises a continuous helical flight projecting inwardly from the side of the drum.

4. Apparatus according to any preceding claim in which the mounting means is adapted to allow the drum to be positioned, during loading, with its axis substantially horizontal.

5. Apparatus according to any preceding claim in which the mounting means is adapted to allow the drum to be positioned, during loading, with the underside of the open end of the drum in contact with or closely adjacent to the ground.

6. Apparatus according to any preceding claim in which the drum is a right-circular cylindrical drum.

7. A method of mixing material comprising the steps of advancing into a pile of material an openended drum having within the drum conveying means for moving material along the drum, rotating the drum in a direction such as to convey material into the drum from the pile, rotating the drum in the same direction as the direction for loading the material, so as to effect mixing within the drum, and rotating the drum in the reverse direction to the loading and mixing direction so as to effect discharge of material from the drum.

8. Apparatus according to claim 7 including the step of moving material along the drum by the effect of at least one vane positioned inside the drum and inclined to the drum axis.

9. A method according to claim 7 or 8 including the step of changing the direction of the drum axis after the loading step, so as to position the drum with the open end upwardly inclined relative to the position for loading.

10. A method according to any of claims 7 to 9 including the step of setting the axis of the drum to be substantially horizontal during the loading step.

11. A method according to any of claims 7 to 10 including the step of positioning the drum with the underside of its open end in contact with or closely adjacent to the ground during loading.

12. Mixing apparatus substantially as hereinbefore described with reference to Figures 1 to 3, or Figures 2, 3 and 4, of the accompanying drawings.

13. A method of mixing material substantially as hereinbefore described with reference to the accompanying drawings.