EP0005604A1

EP0005604A1 - A surface cleaning machine

Info

Publication number: EP0005604A1
Application number: EP79300768A
Authority: EP
Inventors: Charles William Lake; Herb Weber
Original assignee: Worldwide Blast Cleaning Ltd
Current assignee: Worldwide Blast Cleaning Ltd
Priority date: 1978-05-19
Filing date: 1979-05-04
Publication date: 1979-11-28
Also published as: GB1603308A; AR218723A1; EP0032161A1; HK46082A; DK204979A; JPS555282A; BR7903080A; CA1115528A; JPS58155172A; NO791612L; NO820454L; HK45982A; ZA792058B

Abstract

A surface cleaning machine, of the kind in which abrasive grit (6) is projected at high velocity against a surface (1) to be cleaned. The machine has an upper hopper (12) to receive grit carried by rebound and air flow from the zone (4) being cleaned. Adjustable openings (26) provide for controllable air exhaust upstream of the upper hopper (12) which has a controllable outlet (27, 27A) through which grit falls in the form of a curtain (6A) into a main, lower hopper (11). Air is drawn into the main hopper (11) through a controllable inlet (28,28A) and flows through the curtain (6A) to remove dirt from the falling grit. The angle of the blast wheel (3) can be varied, to vary the angle of impact of the projected grit (6) on the surface (1) in the cleaning zone (4).

Description

This invention relates to a surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface to be cleaned. 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. The abrasive grit used is usually fine steel shot and such material will be referred to herein for brevity as "grit". Dirt to be cleaned from the surface may be of various kinds, for example dust, paint, oil, rust, or other contaminants or coverings, and mixtures of them : these will be referred to herein for brevity as "dirt".
Various machines of the type referred to are known, see for example British Patent Specification No. 1,496,268 and U.S. Patent Specifications Nos. 3,034,262; 3,380,196; and 3,691,689.
A machine of the kind referred to above may be required to clean various kinds of surfaces having various kinds of surface contaminants. For example a concrete floor surface may be covered with a mixture of oil and dust, or a metallic tank surface may be covered with a mixture of paint and rust, and so on. But it has been found that satisfactory and quick cleaning of various surfaces and contaminations involves different cleaning conditions. For example some surfaces and cuntaminations can be cleaned more easily than others: thus a lighter weight of grit could be used, or a less powerful blast effec could be used, or a combination of both. Existing machines of the type referred to cannot however give the necessary versatility, particularly in terms of varying the blast-cleaning effect of the grit on the surface to be cleaned.
It has been found in using machines of the kind referred to above that if grit is projected from a blast wheel at a maximum angle of approximately SO to the surface to be cleaned, the blast-cleaning effect is greateal Thus it is the practice to mount the blast wheel and its drive motor so that the grit is flung in a plane generaljy at right angles to the axis of rotation of the wheel along an incident path inclined at 80° to the horizontal, if the machine is used fo cleaning a floor or other horizontal surface. If the machine is used for cleaning a wall or other vertical surface, then the incident path will be at 80° to the vertical. When the grit is projected at the surface at 80° thereto, there is a substantial rebound effect, which is used, together with an air flow, in reclaiming the grit for further use and in transporting the dirt for subsequent removal from a part of the machine remo from the surface.
It has also been found that if the angle is reduced, the blast-cleaning effect will be reduced. Thus for severe contamination, an anglc of 80° could be used, but for less severe contamination, a lesser angle could be used.
The invention is therefore based on the problem of providing a surface cleaning machine of the kind referred to above, which can be readily used for cleaning different kinds of surfaces with different kinds of surface contaminants.
According to this invention there is provided a surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface to be cleaned, the machine comprising:-

i) an enclosure with an opening therein
ii) sealing means disposed around the opening so as to contact the surface to be cleaned and so as substantially to retain abrasive grit and removed dirt within the enclosure
iii) a projecting device for projecting abrasive grit at high velocity along an incident path through the opening to a zone of the surface to be cleaned
iv) a reclaim channel through which passes abrasive grit and dirt from'the cleaned surface zone
v) an air inlet near the said opening for providing an air flow through the reclaim channel
vi) a main receiving container to receive abrasive grit from the reclaim channel for return of the abrasive grit to the projecting device,
characterized in that
- a) an additional receiving container is provided to receive abrasive grit from the reclaim channel, the additional receiving container having an outlet of adjustably variable size
- b) an opening or openings is provided for removal of air from the air flow, the opening or openings being upstream of the abrasive grit received in the additional receiving container
- c) the main receiving container is disposed in such a position in relation to the said outlet that abrasive grit passes in the form of a moving curtain from the additional receiving container to the main receiving container
- d) an air inlet for flow of air into the main receiving container is arranged so that the air passes through the moving curtain of abrasive grit to remove dirt therefrom.

Thus in the machine of the invention the additional receiving container, preferably in the form of a hopper, collects reclaimed grit mixed with dirt. To avoid compaction of the grit in the additional receiving container, air pressure in that container may be reduced by removing air, preferably from the reclaim channel, upstream of the grit in the additional receiving container. The grit mixed with dirt can then flow through the outlet from the additional receiving container and this outlet is of adjustably variable size, sc that the curtain of grit which flows from it into the main receiving container or hopper can be maintained according to the weight or size of grit being used. It is to be noted that different grits will be used for different surfaces and contaminants. The air inlet into the main receiving container provides a flow of air through the curtain of grit entering the main container, to remove the dirt, which is generally of lighter weight than the grit, from the grit. In this way the dirt is blown away from the grit. It is preferable that the air inlet into the main container be of adjustably variable size, so that the air flow through the main container can be varied to suit the various kinds of operating condition. Thus for example for removal of dirt which is light in weight, less air is required to flow through the main receiving container. The opening or openings previded for removal of air from the air flow is or are also p _'crably of variably adjustable size so that the amount of air removed from the air flow can be controlled according to the particular operating requirements.
The projecting device for projecting the abrasive grit may be mounted in the machine so that the angle between the incident path of the projected abrasive grit and the surface to be cleaned can be adjustably varied. Thus if the projecting device is a vaned blast wheel rotatable at high speed, it may be so mounted in the machine that its axis of rotation may be moved, to change the angle of the incident path. Preferably a driving motor, a shaft carrying the blast wheel, and the blast wheel, together with housing parts forming a channel along which the grit is projected, constitute a unit or head which is tiltable as a whole about a hingeing axis.
When the angle between the incident path and the surface to be cleaned is reduced, the rebound effect is reduced and it is necessary to rely more on a flow of air within the machine to reclaim the grit and remove the dirt. It is therefore also necessary to provide for a greater flow of air in the machine than has previously been required. But with known machines, greater air flow produces a higher speed air flow in the reclaim channel, particularly in that in some machines there is a venturi effect by virtue of the shape of the reclaim channel. This produces various disadvantages : the grit, by virtue of its speed of movement and by virtue of the air pressure, can become compacted in the receiving container or hopper to which it is returned before being fed to the blast wheel for re-use; and the grit, by virtue of the friction imparted to it by its high velocity motion in contact with the walls of the reclaim channel, becomes heated, so that some kinds of removed dirt, for example paint, clings to the grit and cannot be easily separated from the grit and evacuated to a dirt collector, which is usually a container to which strong suction is applied and which is usually also the source of the air flow through the machine. Thus, with a greater flow of air to transport dirt away from the cleaned surface zone and along the reclaim path to the receiving container, the air may be largely removed from the air flow so as to reduce the effect of the air flow on the dirt before it reaches the hopper. Preferably the opening or openings is or are in the form of louvres through which the air and some of the dirt is removed to the dirt collector. Preferably also the louvres are adjustably movable to provide for variation of their area, to suit various operating conditions, whereby a greater or lesser amount of air can be removed from the reclaim channel.
The reclaim channel may be in the known form of a closed channel of rectangular cross-section, except that the cross-section is the same or virtually the same throughout the length of the channel from the cleaned surface zone to the additional receiving container when the projecting device is in the position for maximum blast-cleaning effect.
The invention will now be described by way of example with reference to the drawings, in which:-

Figure 1 is a diagrammatic section through a machine in accordance with the invention, as seen on the vertical plane in which the axis of the blast wheel lies;
Figure 2 is a diagrammatic section as seen on a plane at right angles to the plane of figure 1 and looking towards the blast wheel; and
Figure 3 is a diagrammatic enlarged detail section of part of Figure 1.

Referring to the drawings, there is seen a surface cleaning machine of the kind in which a surface 1 to be cleaned is subjected to a high velocity blast 2 of abrasive grit which blast is produced by a vaned blast wheel 3 mounted on a shaft 3A and driven by a hydraulic motor 3B at high speed, for example 3400 to 3850 r.p.m. The machine has an enclosure, formed by the various plates seen in Figure 1, as will be described, and the enclosure has an opening 4 at the surface 1. The opening 4 is rectangular in plan and has sealing means disposed around it; this sealing means comprises double sealing strip members 5A, 5B, 5C and 5D respectively at each side of the opening and in contact with the surface 1. The area of the surface 1 within the opening 4 at any time is the zone which is to be cleaned and to which abrasive material in the form of grit 6 is flung by the blast wheel 3 along an incident path. In the position shown in full lines in Figure 1 the incident path includes an angle of approximately 80° with the surface 1. (Grit is indicated by the reference numeral 6 in several parts of the machine).
The machine is mounted for movement on a forward castor wheel 7A and rear driven wheels 7B, 7C (Fig. 2) driven by a motor (not shown).
The grit rebounds from the surface zone up into a reclaim channel 8 which is formed by a curved front reclaim channel plate 8A; parallel spaced side plates of which one is seen at 8B; and a rear reclaim channel plate 8C which is pivotally swingable about a hinge axis 9 from the full line position to the dot-dash line position shown; it will be seen that in the latter position the plate 8C is still below the upper edges of the spaced side plates 8B, one of which upper edges is indicated at 8B'. The enclosure is formed by the reclaim channel and also by the several plates enclosing the blast wheel : a front plate 10A, rear plate 10B, side plates 10C and top plate 10D.
The machine also includes a main receiving container in the form of a lower hopper 11 which includes inclined forward and rear plates 11A, 11B respectively; an additional receiving container or upper hopper 12 which also includes inclined forward and rear plates 12A, 12B respectively; and a return channel 13 for air and dirt and having upper and lower walls 13A, 13B respectively. At the front of the machine is a dirt collector 14, into which dirt removed from the cleaned surface zone by the grit is sucked and stored, somewhat in the manner of a vacuum cleaner. The dirt collector 14 has an outer box-like casing 14A, the rear wall of which is open at 14B for movement of air and dirt into it. The collector 14 also includes dust bags 15 with support cages 15A. Air flow for the dirt collector and for the whole machine is provided by a fan 16 driven by a hydraulic motor 16A and having an exhaust 16B. A quick release, adjustably programmable electronic pulsar valve 16C and associated air tank 16D are mounted on the casing 14A as shown.
The grit projecting device comprises the vaned blast wheel 3, with its shaft 3A and motor 3B, and the various plates enclosing the blast wheel. This constitutes a unitary structure or head which can be pivotally, adjustably moved about a hinge 17 mounted on the machine side plates 8B. In one embodiment, the blast wheel is 35 cms. in diameter and has seven curved vanes. An operator's handle is seen at 18. The grit projecting device is movable from the full line position to the dot-dash line position and can be fixed in either position, or in an intermediate position, by means not shown. In the full line or 80° position there is maximum cleaning effect and maximum grit rebound effect. These effects decrease progressively in various positions of the head until the minimum dot-dash line position is reached, when the rebound effect cannot be used to any extent for grit reclaim, so that reliance must be placed more on air flow for reclaim of grit. Grit is fed from the main hopper 11 to the blast wheel through a grit flow control valve 19 and extensible flexible corrugated ducting 20. An extensible gas-contrcilcd strut 21 supports the grit projecting device and is connected at its forward end to brackets 21A fixed to the side plates 8B and at its rear end to brackets 21B on the plate 10A. The rear reclaim channel plate 8C is hingedly connected at 22 to the plate 10A, so that when the grit projecting device is moved, the plate 8C moves with it about the hinge 9, and between the side plates 8B.
Within the housing formed by the several plates 10A-10D is a blast liner; this comprises an inner housing of heavy cast metal to contain the grit; it surrounds the blast wheel, as indicated at 23 (Fig. 2) and also defines the path of the projected grit, as indicated at 24. A heavy liner is needed to withstand the wear caused by the grit; normal steel plating as used for other parts of the machine would very quickly be worn away.
The double front and rear sealing members 5A, 5B are all preferably of a resilient urethane strip. There is an additional outer front seal 5E. The double side sealing members comprise an inner manganese steel strip and an outer resilient urethane strip.
An air intake 25 to the cleaning zone includes a brush-like screen 25A which permits entry of air, but retains grit and dirt. The intake 25 is adjustable, for control of the amount of air drawn in. The air intake is at the top of a channel 25B opening downwardly near the surface 1 at the rear of the zone 4. The indrawn air is thus drawn downwardly in a controlled amount to the zone 4; this keeps in motion any grit or dirt which tends to become idle and to accumulate near the rear sealing members 5B as the machine is moved forwardly, that is, to the right as seen in Figure 1.
Also as seen in Figure 1 the reclaim channel S is curved and parallel-sided in the full-line position, so that the air flow upwardly in the reclaim channel 8 is not subject in that position to a venturi effect and its speed is not increased. The construction is such that its cross-sectional area at the level of the hinge 9 remains constant, even when the rear reclaim channel wall 8C is swung upwardly to the dash-dot line position, so that in the latter position the speed increase of the air flow is not significant. The air outlet, and one dirt outlet, from the reclaim channel 8 is by way of openings 26 having rockable louvres or flaps 26D, Figure 3. The construction of these flaps is not shown in detail; they are pivotally mounted and can be opened or closed to the required degree by an arrangement of rollers 26A mounted on a rod 26D movable by a handle 26C as indicated by the double-headed arrow in Figure 3. It will be noted that the air is largely removed from the air flow upstream of the surface 12C of the grit collected in the upper or additional hopper 12, so that downstream of the louvres 26 the air speed and pressure is low whereby compaction of the grit in the upper hopper 12 is not increased.
The wall 13B forms the upper surface of the upper hopper 12 and is a continuation of the wall 8A downstream of the louvres 26. The wall 138 is curved and provides for smooth flow of the grit to the upper hopper 12 and in practice most of the impact of the reclaimed grit is absorbed by the surface 12C of the mass of reclaimed grit already in the upper hopper 12.
From the upper hopper 12 the reclaimed grit falls through an outlet 27 which is of adjustably variable size, having a weight-controlled flap valve 27A and down into the main hopper 11. The flap valve 27A operates in dependence on the weight of the grit in the upper hopper. The less the grit, the less the fall and vice versa. The grit falls in the form of a curtain 6A. In the wall 11A of the main hopper 11 is an air inlet of controllable size, having an adjustable flap valve 2SA, through which inlet air can be drawn so as to pass through the falling curtain 6A of grit and remove more dirt from it; the removed dirt travels along the path indicated by the arrows through the return channel 13 and thence to the dirt collector 14 through the opening 14B. Passage of the air through the curtain 6A assists in further cooling the latter, as well as cleaning it.
The cleaned and cooled grit collects as a mass in the lower or main hopper 11 and is returned by way of the controllable valve 19 and ducting 20 to the blast wheel 3.
In one set of adjusted operating conditions of the machine of the invention, grit flow from the blast wheel is approximately 365 kgs. per minute; air flow in the machine is 34 to 45 cu. metres per minute. The cross-sectional area of the reclaim channel at the level of the hinge axis 9 is approximately 510 sq. cms. The size of the reclaim channel in the present embodiment is 46 cms. x 11.5 cms., the latter dimension being in the plane of the drawing. The total maximum area of the louvres 26 is 175 sq.cms. The air intake is 116 sq.cms. The above is one set of operating conditions. By adjustment of the various parts, other sets of conditions can be provided, according to the cleaning requirement, weight of grit, and so on. For example the degree of opening of the louvres can be varied, as can that of the valve 28, to control the air flow. If necessary louvres of different sizes could be interchangeably fitted.
Referring to Figure 3, the louvres 26D and the flap valve 28A can be operated in unison. This is shown diagrammatically as follows. Fixed to the handle 26C is a pivot lever 26E which is connected by a link 29 to a pivot lever 28B fixed to the pivot shaft 28C of the flap valve 25A. Thus when the handle 26C is operated to adjust the louvres 26D, the flap valve 28A is also adjusted. If the louvres 26D are adjusted to reduce the air flow through them, the flap valve 28A is adjusted to increase the amount of air entering the main hopper 11 through the inlet 28. The flap valve 27A is also connected to the pivot lever 26E by a link 30 in generally similar manner, for control of the amount of grit falling through the opening 27.
It is also possible for the flap valve 28A to be connected to the pivot lever 26E, but not the flap valve 27A. Thus the openings 26 and 28 can be controlled in unison, but the opening 27 can be controlled separately, for example by a lever (not shown) connected to a pivot shaft (not shown) of the flap valve 27A, a weight (not shown) being movably mounted on the lever.

Claims

1. A surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface to be cleaned, the machine comprising:-

i) an enclosure with an opening therein

ii) sealing means disposed around the opening so as to contact the surface to be cleaned and so as substantially to retain abrasive grit and removed dirt within the enclosure

iii)a projecting device for projecting abrasive grit at high velocity along an incident path through the opening to a zone of the surface to be cleaned

iv) a reclaim channel through which passes abrasive grit and dirt from the cleaned surface zone

v) an air inlet near the said opening for providing an air flow through the reclaim channel

vi) a main receiving container to receive abrasive grit from the reclaim channel for return of the abrasive grit to the projecting device,
characterized in that

a) an additional receiving container (12) is provided to receive abrasive grit (6) from the reclaim channel (8), the additional receiving container (12) having an oultet (27) of adjustably variable size

b) an opening or openings (26) is provided for removal of air from the air flow, the opening or openings (26) being upstream of the abrasive grit (6) received in the additional receiving container (12)

c) the main receiving container (11) is disposed in such a position in relation to the said outlet (27) that abrasive grit passes in the form of a moving curtain (6A) from the additional receiving container (12) to the main receiving container (11)

d) an air inlet (28) for flow of air into the main receiving container (11) is arranged so that the air passes through the moving curtain (6A) of abrasive grit to remove dirt therefrom.

2. A surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface to be cleaned, the machine comprising:-

i) an enclosure with an opening therein

iii)a projecting device for projeccing abrasive grit at high velocity along an incident path through the opening to a zone of the surface to be cleaned

vi) a receiving container to receive abrasive grit from the reclaim channel for return of the abrasive grit to the projecting device,
characterized in that

a) an opening or openings (26) is or are provided for removal of air from the air flow, the opening or openings (26) being upstream of the abrasive grit (6) received in the receiving container (11), and

b) the or each opening (26) is of adjustably variable area.

3. A surface cleaning machine of the kind in which abrasive grit is projected at high velocity against a surface to be cleaned, the machine comprising:-

i) an enclosure with an opening therein

a) the device (3,10A,10B,10C,10D) for projecting abrasive grit is so mounted in the machine that the angle between the incident path of the projected abrasive grit and the surface (1) is adjustably variable, and

b) the reclaim channel (8) is of adjustably variable cross-sectional area.

4. A machine according to claim 1 characterized in that air removal openings (26) are arranged in a wall of the reclaim channel (8) upstream of the additional receiving - container (12), the openings (26) being of adjustably variable size for the purpose of controlling the amount of air removed from the reclaim channel (8).

5. A machine according to claim 1 or claim 4 characterized in that the said air inlet (28) of the main receiving container (11) is of adjustably variable size for the purpose of controlling the amount of air passing through the moving curtain (6A).

6. A machine according to any of claims 1, 4 or 5.characterized in that the device for projecting abrasive grit (3, 10A, 10B, lOC, 10D) is so mounted in the machine that the angle between the incident path of the projected abrasive grit and the surface (1) can be adjustably varied.

7. A machine according to claim 6 characterized in that the reclaim channel (8) is of adjustably variable cross-sectional area.

8. A machine according to any of claims 1 or 4 to 7 characterized in that the said outlet (27) is in the form of a pivotally mounted flap valve (27A), opening movement of the said flap valve (27A) being caused by the weight of abrasive grit (6) in the additional receiving container (12) and closing movement of the said flap valve (27A) being caused by a weight adjustably movable along a lever connected to the pivot shaft of the said flap valve (27A).

9. A machine according to claim 5 when dependant on claim 4 characterized in that the air removal openings (26) have movable louvres (26D) and the air inlet (28) has a movable flap valve (28A), the movable louvres (26D) being connected to the movable flap valve (28A) for movement in unison.

10. A machine according to claim 9 characterized in that the said outlet (27) is in the form of a pivotally mounted flap valve (27A) connected to the louvres (26D) and to the said movable flap valve (28A) for movement in unison.

11. A machine according to any of claims 1 and 4 to 10 characterized in that the additional receiving container (12) is disposed above the main receiving container (11) and in such a position in relation to the said outlet (27) that the abrasive grit passes in the form of a falling curtain from the additional receiving container (12) to the main receiving container (11).

12. A machine according to any of claims 1 and 4 to 11 characterized in that the air inlet (25) near the opening (4) is arranged to direct air downwardly to the said zone of the surface (1) to be cleaned, the inlet (25) being of adjustably variable size for the purpose of controlling the air flow through the reclaim channel.