GB2072549A - Improved surface removing or surface cleaning machine - Google Patents

Abstract

In a surface removing or cleaning machine of the kind in which abrasive grit is projected by a blast wheel 5 at high speed against a surface (4), rebounded grit and dirt pass upwardly through a reclaim channel (8A) to a first hopper (9). A current of air (9C) is drawn through the reclaim channel and the first hopper. Grit and dirt fall from the hopper (9) into a drum (16) and are moved axially thereof by an auger (11) to be forced through flap valves (18) to a collecting space (13) whence grit and dirt are lifted by buckets (14) to fall (at 15) into an air wash separator (19). Separated grit falls (at 21A) to a further hopper (24A) for return to the blast wheel (5). <IMAGE>

Description

SPECIFICATION Improved surface removing or surface cleaning machine This invention relates to a surface removing or surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface. Thus the surface is subjected to an abrasive blast which is produced for example by a vaned blast wheel rotating at high speed, to fling or project the abrasive grit with great force on to the surface so as to blast-clean from it all dirt or to remove it to a required depth. For example, it is sometimes required to remove concrete to a given depth from a surface, to provide a new surface. The abrasive grit used is usually fine steel shot and such material will be referred to herein for brevity simply as "grit".Materials to be cleaned or removed from the surface may be of various kinds, for example dust, paint, oil, rust, or other contaminants or coverings, and mixtures of them, or concrete; these materials will be referred to herein for brevity simply as "dirt".

Surface cleaning machines have become well-known in recent years and have been used quite extensively. In such a machine the grit rebounds from the surface being cleaned and carried with it the removed dirt. The rebounded grit and the removed dirt pass into and through a reclaim channel which leads to a device or devices for separating the dirt from the grit so that the latter can pass to a receiving container for return to the blast wheel. It has however always been a problem with these machines to remove dirt satisfactorily from the grit. If the dirt is not substantially wholly removed, then the amount of dirt in the re-used grit affects the surface cleaning property of the grit when it is again projected at a surface to be cleaned. Also the dirt deleteriously affects return of the grit to the blast wheel.These disadvantages apply even more when for example concrete is being removed from a surface to a required depth, because more grit is in use and more concrete dust is being removed.

It is an object of this invention to provide a machine which can be used to remove a surface, particularly for example a concrete floor surface, or to clean a heavily contaminated surface.

According to this invention there is provided a surface removing or a surface cleaning machine of the kind in which grit is projected at high velocity against a surface, the machine comprising: i) an enclosure with an opening therein ii) sealing means disposed around the opening so as to contact the surface and so as substantially to retain grit and removed dirt within the enclosure iii) a projecting device for projecting grit at high velocity along an incident path through the opening to a zone of the surface iv) a reclaim channel through which pass rebounded grit and dirt from the surface zone v) a receiving container for the grit and dirt, which container is in communication with the reclaim channel and with a source of reduced air pressure for the purpose of drawing air through the reclaim channel and the receiving container vi) means for conveying grit and dirt in substantially air-tight manner away from the receiving container towards a collecting space whence the grit and dirt are lifted to an upper location vii) an air cleaning stage through which the grit and dirt descend from the upper location, in which stage dirt is blown from the grit; and viii) means for returning grit from the air cleaning stage to the projecting device.

An embodiment of the invention will now be described by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a side sectional elevation; Figure 2 is an elevation as viewed from the right-hand side of Fig. 1, with parts omitted; Figure 3A is a perspective detail view of a fixed cylinder or drum in the machine; and Figure 3B is a perspective detail view of one of two flap valves, which in use are mounted on the drum shown in Fig. 3A.

Referring to the drawings, a surface cleaning machine, of the kind in which grit is projected in known manner at high velocity against a surface 4 to be cleaned or otherwise treated, comprises an enclosure 1 with an opening 2 therein and sealing means 3 disposed around the opening 2 and in contact with the surface 4. The sealing means 3 retains substantially all the grit and removed dirt within the enclosure 1, although air can enter the enclosure by being drawn in through the sealing means 3. Air is drawn in by an exhaust fan (not shown) to which an outlet 10 leads.

A known grit projecting device includes a vaned blast wheel 5 driven by a motor 5A so that grit 6A is projected at high velocity along an incident path 6C through the opening 2 on to a zone of the surface 4.

The grit 6A rebounds from the surface 4 along a path 6B into a reclaim channel 8. Dirt removed from the surface is partly carried along with the grit and partly carried in the air stream in the reclaim channel 8. A first, downstream portion 8A of the reclaim channel is curved and of diminishing cross-sectional area in the direction of flow, as shown. A second, upstream portion 8B of the reclaim channel is straight and parallel-sided, whilst a final portion 8C is curved and parallel-sided, as shown, and opens above a first grit and dirt receiving container. The latter is in the form of a hopper 9 closed at its lower end, as will be described below. Extending laterally below the lower part of the hopper 9 is an auger (indicated schematically at 11 in Figs. 1 and 2) mounted on a lateral, driven shaft 11 A.The upper part 9A of the hopper 9 is open to a pair of parallel exhaust ducts 9B (one at each side of the reclaim channel 8) which ducts lead to the outlet 10, which is connected to a suction fan, as mentioned above. Thus lightweight particles of dirt, for example fine dust which is unattached to grit particles, are drawn away in the direction indicated by the arrows 9C. The auger 11 rotates within a fixed drum 1 6 which is closed at its left hand end (Fig. 2) by a wall 1 6A of the machine. The drum 1 6 closes the lower end of the hopper 9; it has two slots 1 6B (see also Fig. 3A) which communicate with the said lower end, so that grit and dirt descend from the hopper 9 into the auger 11 within the drum 16. The clearance between the auger and drum is small.

Referring to Figs. 2, 3A and 3B, the drum 1 6 is continued at its right hand end with a fixed drum portion 17, closed at its right hand end by an end disc 17A, and into which portion the rotatable auger 11 extends, as seen in Fig. 2. The drum portion 1 7 has two slots 17B, each closed by a flap valve 18, shown separately in Fig. 3B. Each flap valve 1 8 has a housing 1 8A open at the side which mates with the relevant slot 1 7B and at the other side having a flap 1 8C of heavy flexible material (for example urethane strip 1 /8" thick) fixed to the box by a strip 18D.As the auger 11 drives the grit and dirt into the drum portion 17, pressure builds up, until the grit and dirt force the flap valves open, so that the grit and dirt fall through the two flap valves 18.

This construction of hopper 9, drum 16, 1 7, slots 1 6B, 1 7B and flap valves 18, prevents inflow of air (caused by the air flow 9C) through the valves 18, which are effectively blocked by the grit and dirt forced by the auger 11 against them. Thus reduced air pressure is maintained in the hopper 9, reclaim channel 8 and enclosure 1.

The grit and dirt fall from the drum portion 1 7 through the valves 1 8 into a perforated cylinder or drum 1 2 which is mounted on the right hand end (Fig. 2) of the shaft 1 1A by spokes 11 B. The drum 1 2 is within a circular housing 1 3A which also forms a grit collecting space 13. The wall of the drum 12 is perforated so that grit and dirt will fall by gravity out of the rotating drum 1 2 into the collecting space 1 3. The size of the perforations (not shown) is such that any particles or foreign bodies greater than 3/16" in size will not fall through into the space 1 3 but will continue to move laterally, for separate removal and collection.In this way, damaging foreign bodies are not returned to the vaned blast wheel 5. It will be seen from Fig. 2 that the drum 1 2 has an internal helical blade 1 2A which moves to the right particles which have not fallen through the perforated wall of the drum. These particles fall out past a lip 1 2B of the open end 1 2C of the drum 1 2.

The drum 1 2 has cylindrical outer drum portions 1 2D which have axially extending slots (not shown) through which grit and dirt fall into the collecting space 1 3.

Between the drum portions 1 2D the drirm 1 2 drivingly mounts the lower end of a bucket conveyor hoist 1 4 with buckets 1 4A (only a few of which are shown). The hoist 14 is mounted at the upper end on an upper drum 14B (Fig. 1). The buckets 14A dip into grit and dirt in the collecting space 1 3 and carry it upwardly and over the upper drum 1 4B, depositing it as indicated at 1 5 down to an air cleaning housing 1 9 in which dirt particles (which are relatively light) are blown from the grit particles (which are heavier).

Referring to Fig. 1, the air cleaning housing 1 9 is shown diagrammatically. The grit and dirt falls as indicated at 1 5 into a hopper 1 9A and descends to an outlet opening 1 9B of the hopper, the size of which opening is con trolled by an adjustably movable first flap 1 9C. By this means flow of grit and dirt down out of the hopper 1 9A can be controlled. The two end positions of the flap 1 9C are shown by dotted lines.

At the left hand side of the housing 1 9 (as viewed in Fig. 1) is an air inlet 20A, whilst below and to the right of the hopper outlet opening 1 9B is an air outlet 20B, communi cating by way of a space 20C with the opening 10. By this means a current of air (as indicated by the dashed and arrowed line) is drawn across a space 21 below the hopper 19.

Of the grit and dirt falling from the hopper outlet opening 1 9B, the heavy abrasive grit particles tend to follow the path indicated at 21A, whilst the lighter dirt particles tend to follow the path indicated at 21 B, by virtue of the action of the transverse current of air; and also by virtue of an adjustably movable sec ond flap 22. This flap 22 assists in positively separating the grit from the dirt, particularly heavier dirt particles such as sand. Lighter dirt particles such as dust are carried away in the current of air to the outlet 20B and space 20C. The flap 22 can be moved to separate the grit and dirt according to the nature of the grit and dirt and the characteristics of their fall from the hopper outlet opening 1 9B. Heavier dirt particles like sand fall to a space 23A having a discharge outlet 23B. The grit falls to a second, lower hopper 24A whence it returns in known manner by way of a passage 24B to the blast wheel 5. Dirt is conveyed out by the air stream through the opening 10 to a dust collecting container, as is known.

As has been stated, the machine of the invention not only can clean a heavily contaminated surface, but can remove for example concrete from a concrete floor to a required depth. The machine is capable of dealing with substantial quantities of removed debris in the form of dirt and concrete dust and particles, yet will prevent particles of a damaging size from reaching the blast wheel when the abrasive grit is reclaimed and re-cycled. The perforated drum prevents the latter occurrence, and the air cleaning stages (including that in the upper part 9A of the hopper 9) provide for removal of the debris.

The machine can operate relatively quietly as compared with known concrete surface removing machines, which incorporate mechanically driven chisels or rotary diamond cutter flails. These are not only very noisy; they leave the debris behind them. The machine of the invention retrieves virtually all its own debris, so that a fresh surface, ready for painting or otherwise treating, results.

Although the machine has been designed primarily for working on a concrete surface, it can also be used for cleaning other surfaces, for example a steel floor or deck.

The machine would be carried on a wheeled chassis, which would also incorporate an operator's platform and control station, as well as a power unit, and a dust collecting container, in known manner.

Claims (18)

1. A surface removing or a surface cleaning machine of the kind in which grit is projected at high velocity against a surface, the machine comprising: i) an enclosure with an opening therein ii) sealing means disposed around the opening so as to contact the surface and so as substantially to retain grit and removed dirt within the enclosure iii) a projecting device for projecting grit at high velocity along an incident path through the opening to a zone of the surface iv) a reclaim channel through which pass rebounded grit and dirt from the surface zone v) a receiving container for the grit and dirt, which container is in communication with the reclaim channel and with a source of reduced air pressure for the purpose of drawing air through the reclaim channel and the receiving container vi) means for conveying grit and dirt in substantially air-tight manner away from the receiving container towards a collecting space whence the grit and dirt are lifted to an upper location vii) an air cleaning stage through which the grit and dirt descend from the upper location, in which stage dirt is blown from the grit; and viii) means for returning grit from the air cleaning stage to the projecting device.

2. A machine according to claim 1 wherein the said means for conveying comprises a device which pushes grit and dust into a space having valve means, such that the pressure of grit and dust in the space causes the grit and dust to pass through the valve means in a blocking manner substantially preventing entry of air into the space through the valve means.

3. A machine according to claim 2 wherein the said means for conveying comprises a drum and an auger rotatable therein, the drum closing the receiving container but permitting grit and dirt to pass from the receiving container into the drum to be conveyed by the auger.

4. A machine according to claim 3 wherein the drum and auger have a common horizontal axis.

5. A machine according to claim 3 or claim 4 wherein the said space is a closed end portion of the drum.

6. A machine according to any of claims 2 to 5 wherein the valve means comprises flap valves.

7. A machine according to any of claims 2 to 6 wherein the grit and dust pass through the valve means into a rotatable perforated drum, which conveys large dirt particles laterally but allows grit and small particles to fall to the collecting space.

8. A machine according to any preceding claim wherein grit and dirt are lifted from the collecting space by a bucket lift to the upper location.

9. A machine according to any preceding claim wherein the air cleaning stage comprises a hopper into which the lifted grit and dirt fall, and an air inlet and an air outlet so disposed as to produce a lateral current of air below the hopper, whereby grit and dirt falling from the hopper are separated by the dirt being blown from the grit.

10. A machine according to claim 9 wherein the air cleaning stage includes an adjustably movable flap positioned below the hopper so that falling grit is caused to pass to one side of it.

11. A machine according to claim 9 or claim 10 wherein the hopper has an adjustably movable flap to control the size of the outlet opening of the hopper.

1 2. A machine according to any of claims 9 to 11 wherein a separate outlet is provided for heavier dirt, for example sand.

1 3. A machine according to claim 6 wherein each flap valve includes a flap of flexible material.

14. A machine according to claim 1 3 wherein the material is a strip of flexible urethane.

1 5. A machine according to any of claims 6, 1 3 and 14 having two flap valves.

16. A machine according to claim 7 when dependant on claim 3, wherein the auger and the perforated drum are mounted on a com mon drive-shaft.

1 7. A machine according to claim 8 when dependant on claim 3 wherein the auger and the bucket lift have a common drive shaft.

18. A surface removing or cleaning machine constructed and arranged substantially as herein described and shown in the drawings.