GB1603308A - Abrasive throwing machine - Google Patents

Description

( 21) Application No 20720/78

( 22) Filed 19 May 1978 ( 44) Complete Specification published 25 Nov 1981 ( 51) INT CL 3 B 24 C 3/06 9/00 ( 52) Index at acceptance B 3 D 8 A 3 ( 72) Inventors CHARLES WILLIA Mv LAKE HERB WEBER ( 54) AN ABRASIVE THROWING MACHINE ( 71) We, WORLDWIDE BLAST CLEANING LMITED, a company organised under the Commonwealth of the Bahamas, of P O.

Box N-7788, Nassau, Bahamas, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:-

This invention relates to a surface cleaning machine of the type by which a surface to be cleaned 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 material with great force on to the surface so as to blast-clean from it all dirt The abrasive material used is usually lead shot and such material will be referred to herein for brevity simply as "shot" 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 simply 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

Specification Nos 3,034,262; 3,380,196; and

3,691,689.

A machine of the type referred to will be required to clean various kinds of surfaces having various kinds of surface contamination 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 Btu it has been found that satisfactory and quick cleaning of various surfaces and contaminations involves different cleaning conditions For example some surfaces and contaminations can be cleaned more easily than others: thus a lighter weight of shot could be used, or a less powerful blast effect 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 shot on the surface.

It has been found in using machines of the type referred to that if shot is projected from a blast wheel at a maximum angle of approximately 80 to the surface being cleaned, the blast-cleaning effect is greatest 55 Thus it is the practice to mount the blast wheel and its drive motor so that the shot is flung generally at right angles to the axis of rotation of the wheel along an incident path inclined at 80 ' to the horizontal, if 60 the machine is used for 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 800 to the vertical When the shot is pro 65 jected at the surface at 800 thereto, there is a substantial rebound effect, which is used, together with an air flow, in reclaiming the shot for further use and in transporting the dirt for subsequent removal from a part 70 of the machine remote 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 angle of 80 could be used, but for less 75 severe contamination, a lesser angle could be used But if the angle between the incident path and the surface is reduced, the rebound effect is reduced and it is necessary to rely more on a flow of air within the 80 machine to reclaim the shot and remove the dirt It is therefore 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 85 a higher speed air flow in the reclaim channel of the machine, particularly in that in some machines there is a venturi effect by virtue of the shape of the reclaim channel This produces various disadvan 90 tages: the shot, by virtue of its speed of movement, can become compacted in the hopper to which it is returned before being fed to the blast wheel for re-use; and the shot, by virtue of the friction imparted to 95 it by its high speed motion in contact with the surfaces of the reclaim channel, becomes heated, so that some kinds of removed dirt, for example paint, clings to the shot and cannot be easily separated 100 PATENT SPECIFICATION

0 o en en ( 11) 1 603 308 1 603 308 from the shot 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.

According to this invention there is provided a surface cleaning machine of the type 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 receiving container to receive abrasive grit from the reclaim channel for return of the abrasive grit to the projecting device characterized in that an opening or openings is or are provided for removal of air from the air flow, the opening or openings being upstream of the abrasive grit received in the receiving container.

Thus, with a greater flow of air to transport shot away from the said zone and along the reclaim channel to the container, air may be removed from the channel so as to reduce the effect of the air flow on the shot before it reaches the container Preferably the opening or openings are louvres through which the air and some of the dirt is removed to a 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 said zone to the said opening or openings for removal of air from the air flow, when the shot projecting or blasting device is in a position for maximum blast-cleaning effect.

Also according to this invention there is provided a surface cleaning machine of the type 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 70 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 75 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 80 abrasive grit from the reclaim channel for return of the abrasive grit to a projecting device, characterized in that a) an additional receiving container is 85 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 90 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 dis 95 posed 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 10 ( 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 one form of the machine of the 10 ' invention an 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 con 11 C tainer 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 11 ' receiving container and this outlet is of adjustably variable size, so 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 120 grit being used It is to be noted that different grits will be used for different surfaces and contaminents The air inlet into the main receiving container provides a flow of air through the curtain of grit entering 12 ' 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 ad 13 C 1 603 3033 justably 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 provided for removal of air from the air flow is or are also preferably 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 IS 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.

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 type by which a surface 1 to be cleaned is subjected to an abrasive blast 2 which is produced by a vaned blast wheel 3 mounted on a shaft 3 A and driven by a hydraulic motor 3 B 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 around it; this sealing means comprises double sealing strip members 5 A, SB 5 C and SD respectively at each side of the opening The area of the surface 1 within the opening 4 at any time is the zone to which abrasive material in the form of shot 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 800 with the surface 1.

The machine is mounted for movement on a forward castor wheel 7 A and rear driven wheels 7 B, 7 C driven by a motor (not shown).

The enclosure is formed by a curved front reclaim channel plate 8 A; parallel 70 spaced side plates of which one is seen at 8 W; and a rear reclaim channel plate 8 C which is pivotally swingable about a hinge axis 9 from the full line position to the dotdash line position shown; it will be seen 75 that in the latter position the plate 8 C is still below the upper edges of the spaced side plates 8 B, one of which upper edges is indicated at SB' The enclosure is also formed by the several plates enclosing the 80 blast wheel: a front plate l OA, rear plate l OB, side plates IOC and top plate IOD.

The machine also includes a primary or lower hopper 11 which includes inclined forward and rear plates l IA, IIB respectively; 85 a secondary or upper hopper 12 which also includes inclined forward and rear plates 12 A, 12 B respectively; and a return channel 13 for air and dirt and having upper and lower walls 13 A, 13 B respectively At the 90 front of the machine is a dirt collector 14, into which dust and so on removed from the cleaned surface by the shot is sucked and stored, somewhat in the manner of a vacuum cleaner The dirt collector 14 has 95 an outer box-like casing 14 A, the rear wall of which is open at 14 B for movement of air and dirt into it The collector 14 also includes dust bags 15 with support cages A Air flow for the dirt collector and for 100 the whole machine is provided by a fan 16 driven by a hydraulic motor 16 A and having an exhaust 16 B A quick release, adjustably programmable electronic pulsar valve 16 C and associated air tank 16 D are 105 mounted on the casing 14 A as shown.

The shot projecting or blasting device comprises the vaned blast wheel 3, with its shaft 3 A and motor 3 B, and the various plates enclosing the blast wheel This con 110 stitutes a unitary structure or head which can be pivotally, adjustably moved about a hinge 17 mounted on the machine side plates 8 B In one embodiment, the blast wheel is 131 inches in diameter and has 115 seven curved vanes An operator's handle is seen at 18 The shot projecting device or structure is movable from the full lines position to the dot-dash lines position and can be fixed in either position, or in an inter 120 mediate position, by means not shown In the full lines or 80 position there is maximum cleaning effect and maximum shot rebound effect These effects decrease progressively in various positions of the head 125 until the minimum dot-dash lines position is reached, when the rebound effect cannot be used to any extent for shot reclaim, so that reliance must be placed more on air flow for reclaim of shot Shot is fed from 130 1 603 308 the primary hopper 11 to the blast wheel through a shot flow control valve 19 and extensible flexible corrugated ducting 20 An extensible gas-controlled strut device 21 supports the shot projecting device and is connected at its forward end to brackets 21 A fixed to the side plates 8 B and at its rear end to brackets 21 B on the plate 10 A.

The rear reclaim channel plate 8 C is hingedly connected at the pivot point shown in Fig 1 to the plate 1 OA, so that when the shot projecting device is moved, the plate 8 C moves with it about the hinge 9, and between the side plates 8 B. Within the housing formed by the several plates IOA-IOD is a blast liner; this comprises an inner housing of heavy cast metal to contain the shot; it surrounds the blast wheel, as indicated at 23 (Fig 2) and also defines the path of the projected shot, as indicated at 24 A heavy liner is needed to withstand the wear caused by the shot; normal steel plating as used for other parts of the machine would very quickly be worn away.

The double front and rear sealing members 5 A, SB are all preferably of a resilient urethane strip There is an additional outer front seal 5 E 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 25 A which permits entry of air, but retains shot and dirt.

The intake 25 is adjustable, for control of the amount of air drawn in The air intake is at the top of the channel seen in Fig.

1 which opens 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 shot or dirt which tends to become idle near the rear sealing members SB.

As seen in Figure 1 the reclaim path or channel is curved and parallel-sided in the full-time position, so that the air flow upwardly in the reclaim channel is not subject 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 8 C is swung upwardly to the dash-dot line position, so that in that position the speed increase of the air flow is not significant The air outlet, and an outlet for some of the dirt, from the reclaim channel is by way of rockable louvres or flaps 26, see the arrows in Figure 1, and also see 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 26 A mounted on a rod 26 B movable by a handle 26 C as indicated by the double-headed arrow It will be noted that the air is largely removed from the reclaim path upstream of the hoppers 12 and 11, so that downstream of the louvres 26 the air speed and pressure is low whereby 70 compaction of the shot in the upper hopper 12 is not increased.

The wall 13 B forms the upper surface of the hopper 12 and is a contamination of the wall 8 A downstream of the louvres 26 75 The wall 13 B is curved and provides for smooth flow of the shot to the secondary hopper 12 and in practice most of the impact of the reclaimed shot is absorbed by the surface of the mass of reclaimed shot 80 already in the hopper 12.

From the secondary hopper 12 the reclaimed shot falls by way of a weight-controlled flap valve 27 down into the primary hopper 11 The flap valve 27 operates in 85 dependence on the weight of shot in the secondary or upper hopper The less the shot, the less the fall and vice versa The shot falls in the form of a curtain In the wall I IA of the hopper 11 is a controllable 90 air inlet flap valve 28, through which air can be drawn in so as to pass through the falling curtain of shot and remove more dirt from it; the removed dirt travels along the path indicated by the arrows through 95 the return channel 13 and thence to the dirt collector 14 through the opening 14 B. Passage of the air through the curtain of shot assists in further cooling the latter, as well as cleaning it 100 The cleaned and cooled shot collects as a mass in the primary hopper and is returned by way of controllable valve 19 and ducting 20 to the blast wheel.

In one set of adjusted operating condi 105 tions of the machine of the invention, shot flow from the blast wheel is 800 Ibs per minute; air flow in the machine is 1200 to 1600 cu ft per minute (which is a number 1 l to 2 times the shot flow number) The 110 cross-sectional area of the reclaim channel at the level of the hinge axis 9 is approximately 80 sq inches (which is a number % of the shot flow number or say I square inch per 10 Ibs of shot per minute) 115 The size of the reclaim channel in the present embodiment is 18 inches x 41 inches, the latter dimension being that in the plane of the drawing The total maximum area of the louvres 26 is 27 sq inches, approxi 120 mately one third of the area of the reclaim channel The air intake is 18 sq inches, approximately two thirds of the area of the louvres The above is one set of operating conditions By adjustment of the various 125 parts, other sets of conditions can be provided, according to the cleaning requirement, weight of shot, and so on For example the degree of opening of the louvres can be varied, as can that of the valves 28, to 130 1 603 308 control the air flow If necessary louvres of different sizes could be interchangeably fitted.

Other features of the machine described above are claimed in co-pending application No 34139/80 (Serial No 1 603 309), which was divided from the present application.

Claims (12)

WHAT WE CLAIM IS:-

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 aditional 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 reeciving 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

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 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 70 cleaned surface zone v) an air inlet near the said opening for providing an air flow through the reclaim channel vi) a receiving container to receive 75 abrasive grit from the reclaim channel for return of the abrasive grit to the projecting device, characterized in that an opening or openings is or are provided for removal of air 80 from the air flow, the opening or openings being upstream of the abrasive grit received in the receiving container.

3 A machine according to claim 1 or claim 2 characterized in that the air re 85 moval openings are arranged in a wall of the reclaim channel upstream of the receiving container, the openings being of adjustably variable size for the purpose of controlling the amount of air removed from 90 the reclaim channel.

4 A machine according to claim 1 or claim 3 when dependent on claim 1 characterized in that the said air inlet of the main receiving container is of adjustably variable 95 size for the purpose of controlling the amount of air passing through the moving curtain.

A machine according to any preceding claim characterized in that the or each 100 opening is of adjustably variable area.

6 A machine according to any preceding claim characterized in that the device for projecting abrasive grit is so mounted in the machine that the angle between the 105 incident path of the projected abrasive grit and the surface can be adjustably varied.

7 A machine according to claim 6 characterized in that the reclaim channel is of adjustably variable cross-sectional area 110

8 A machine according to claim I or claim 4 characterized in that the said outlet is in the form of a pivotally mounted flap valve, opening movement of the said flap valve being caused by the weight of 115 abrasive grit in the additional receiving container and closing movement of the said flap valve being caused by a weight adjustably movable and connected to the pivot shaft of the said flap valve 120

9 A machine according to claim 4 characterized in that the air removal openings have movable louvres and the air inlet has a movable flap valve, the movable louvres being connected to the movable flap 125 valve for movement in unison.

A machine according to claim I characterized in that the additional receiving container is disposed above the main receiving container and in such a position 130 1 603 308 in relation to the said outlet that the abrasive grit passes in the form of a falling curtain from the additional receiving container to the main receiving container.

11 A machine according to any preceding claim characterized in that the air inlet near the opening is arranged to direct air downwardly to the said zone of the surface to be cleaned, the inlet being of adjustably variable size for the purpose of controlling the air flow through the reclaim channel.

12 A surface cleaning machine constructed and arranged substantially as herein described and shown in the accompanying drawings.

WITHERS & ROGERS, Chartered Patent Agents, 4, Dyer's Buildings, Holborn, London, ECIN 2 JT.

Agents for the Applicant.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd, Berwick-upon-Tweed, 1981.

Published at the Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.