GB2239412A - Apparatus for abrasive treatment of surfaces - Google Patents

Abstract

Apparatus for treating a surface 19 has an impeller 11 for delivering particulate abrasive down a delivery section D to hit the surface 19 and the abrasive, mixed with debris from the surface, passes up a rebound section R to a separator section. The mixture hits surface 34 and fails onto and over a weir 35, 36, passes through gap 38. Large debris is removed by filter 40, very fine dust is removed by suction device 32, more debris is removed by filter 45, further filters 47c, 50a remove debris and too small abrasive and the abrasive returns to abrasive hopper 43 and thence to the impeller. Fresh full-size abrasive is supplied through passage 84 from a storage hopper 83 to restore the composition of the abrasive mix to within desired limits. <IMAGE>

Description

APPARATUS FOR TREATING SURFACES This invention relates to apparatus for treating surfaces.

According to this invention apparatus for treating surfaces comprises means for delivering particulate material along a delivery section to hit a surface to be treated, a rebound section through which passes a mixture of particulate material after hitting the surface and debris removed from the surface, and a receiving section for receiving the mixture from the rebound section, the receiving section including filter means for the mixture.

Further aspects and features of embodiments of the invention will be apparent from the following description and claims.

The invention may be performed in various ways and some specific embodiments with possible modifications will now be described by way of example with reference to the accompanying somewhat diagrammatic drawings, in which: Fig. 1 is a side view part in section; Fig. 2 is a front view along arrow A of Fig. 1; Fig. 3 is a transverse section of part of a base unit; Fig. 4 is a side view of a collector; Fig. 5 is 2 view from the right of Fig. 4; Fig. 6 is a schematic view of a treatment unit; Figs. 7 and 8 are views of parts of rebound sections; Fig. 9 shoves a separator; Fig. 10 is a part view on arrow B of Fig. 1; Fig. 11 is a perspective view of a seal element; Figs. 12 and 13 are side and rear views of a delivery section; Figs. 14 and 15 are side views of modifications; and Figs. 16 and 17 are side and end views of a modification.

Apparatus 10 for treating surfaces comprises a delivery section D including an impeller 11 mounted in a straight delivery channel 12 for rotation about an axis 13 by an electric or hydraulic motor 14. The impeller 11 has a plurality of angularly spaced radial blades 15 each lying in a plane containing the axis 13. The speed of the impeller can be varied. Particulate abrasive material for example steel shot 16 is admitted to the channel 12 through an axial input conduit 17 under the control of a manually operable valve 18 and is flung by the impeller 11 along the delivery channel 12 to hit a surface 19 to be treated.The delivery channel 12 has an uninterrupted delivery mouth 20 extending across the bottom end of the channel 12. The shot 16 leaves the impeller 11 at a very fast speed and hits the surface 19 removing pieces from the surface to forn debris. The shot rebounds from the surface 19 and passes up a rebound section R having two or more channels 21 (four in the case shown). The impeller 11 tends to deliver the shot to one side of the delivery mouth 20 and if the rebound section R has an uninterrupted inlet mouth at its bottom end this would tend to give undue wear at one side of the rebound section and poor separation of debris fron the steel shot.In the present case the rebound section R has an interrupted inlet mouth 23a formed by the inlet mouths 23 of the four channels 21 to give reduced wear. At its lower end each channel has a portion 22 with a generally rectangular mouth 23 leading to a rectangular outlet 24 connected to a straight element 25 of uniform rectangular cross-section connected at its top to a curved portion 26 of the same uniform rectangular section bolted at 34 to a separator and hopper section 27.

Portion 26, element 25 and portion 22 may be connected by bolted flanges 28, 29, and element 25 may be in sections connected by bolted flanges 82.

The section 27 has side walls 30a, a top wall 30 having an aperture 31 to which suction is applied by a suction device 32 mounted on the wall 30, and bottom walls 30b.

mixture of steel shot and debris (abraded from the surface 19) enters the section 27 through the outlets of sections 26, may be deflected slightly upwards by transverse plate 33, hits vertical wall 34, secure at 34a to wall 30, thus losing its forVvard motion and falls into an upwardly facing transverse channel member 35 having an upstanding wall 36 at its front to act as a weir. The mixture piles up behind the weir and flows over the weir 9 with the help of the flow of air in the region of the weir into a gap 38 between a transverse flat plate 37 and the member 35.The impact of the air flowing in gap 38 on the mixture of shot and debris assists the separation of debris from shot and deflects the debris towards the suction device 32 and the shot is also deflected rearwards but with lesser effect.

The plate 37 is hinged at its front ede 37a so as to make it possible to vary the gap 38 to adjust the velocity effect of air flowing through the gap 38. Air is sucked through aperture 71, mentioned below, and flows up the channels 21 and through the gap 38 and out through aperture 31. The mixture flows over the weir into the fast-floing air stream flowing through the gap 38. Very light debris similar to talcum powder, passes straight to aperture 31 and through device 32 to a separator.The gap 38 is set before use of the machine on a particular surface 19 and is based largely on experience and depends on the nature of the surface, the treatment or abrasion it is to receive, the nature of the debris, the composition of the steel shot or other abrasive particulate material used, the speed of the impeller. It.

will be appreciated that the composition or working mix of the steel shot can be selected dependent on the surface and the desired treatment. Thus the shot may all be of essentially the same size or diameter or the shot may have two or more portions of different diameter, the diameters and the relative amounts of the different portions being adjustable. For example the initial mix may be from lmm to 3mm with most of the mix being 3mm. Smaller diameter shot will generally leave a smoother finish on the surface 19 after treatment.

The mixture passing through the gap 38 engages an upward mesh 40 (for example 2.5cm) and larger pieces of debris are caught by the mesh and fall under gravity into a compartment 41 from which the debris can be removed through an openable side door 42.

The mixture after passing through mesh 40 is above a shot hopper 43. Dust and very light particles of debris pass under a plate 44, which depends from wall 30, to the suction device 32 and the shot and remaining debris fall onto a horizontal mesh 45. The plate 44 can be pivoted about a top hinge 44a to lie beneath wall 30. Some debris is collected on the mesh 45 and can be removed through an openable side door 46. The remaining debris and the shot pass through mesh 45 and fall by gravity onto a tundish collector 47 having a top filter and material which passes through the filter falls into a receptacle 48 via an open bottom mouth 48b Fig. 1 or via a pipe 48a Figs. 4, 5.

The collector 47 acts as a filter and may be as shown in Figs. 4, 5 having upper downwardly diverging mesh walls 47a leading to converging walls 47b connected to pipe 48b. The walls 47a are covered by removable walls of smaller mesh 47c. The mesh size of walls 47c can be selected as appropriate or desired for the particular surface being treated. If desired receptacle 48 may receive some suction to assist in collecting the debris in the receptacle. In some case, for example using small steel shot on a steel surface 19 the walls 47c can be covered by a removable plate as the debris may be largely dust.

The mesh size of filter or sieve walls 47c is preferably selected so as to permit shot which has been reduced in size by wear to pass through the walls 47c into receptacle 48 thus continuously removing shot which has been reduced to a size less than desired having regard to the nature of the surface being treated and the treatment it is desired to give to that surface. The remaining shot returns to the hopper for re-use. The shot level in the hopper 43 is for example initially at 49 before starting the machine but during operation is at level 49a for example.

The mesh 40 may be of larger size than mesh 45 e.g.

2.5cm. and 1 cm. respectively. The lower part of mesh 40, in the compartment, may have a smaller mesh e.g. 1cam.

During use, the shot can become worn which may result in a change in the treatment given to surface 19. To counteract this, shot of less than a predetermined diameter is removed and fresh shot of greater diameter is placed in the hopper. The shot added is all of the largest dimension being used in the particular case and is added by storage hopper 83 via tube 84 to maintain the level of shot in the hopper. By this means the composition of the working mix of shot may be maintained substantially constant or within acceptable or desired limits and the treatment given to surface 19 is maintained substantially uniform over the surface or within acceptable or desired limits of uniformity.

A container 50 in the hopper has a top mouth formed by a support mesh covered b a removable mesh 50a of selected size and having lower outlets 51 for removal of medium to light dust which has passed through the mesh 50a and which fall into receptacle 48; removal may be assisted by suction.

The receptacle 48 is in a housing 48a having front, rear and side walls and is supported on bottom rollers 48b so as to be removable througii an openable side door for emptying.

The receptacle may have one or more handles 48c.

A treatment region 60 wig. 3 is defined by a support structure 61 having a top wall 62 and a depending peripheral wall 63 normally spaced at its lower end 64 from the surface 19 but supporting at the sides inner wear plates 65 whose lower edges normally engage surface 19 to provide a suction compartment. The replaceable plates 65 are in lengths removably held by clips 66 connected to springloaded elements 67 movable up and down in top wall 62 so that the plates 65 are resiliently urged into engagement with the surface 19. One or more further peripheral seals 70 may be removably secured to the outer sides of the wall 63 for engaging surface 19. The seals 70 may be in three layers of different thicknesses and may be of plastics.

The plates 65 may be of steel.

At the re & air is sucked into the compartment 60 through aperture 71 thus stirring up any shot which may not have rebounded into the rebound section and allowing the suction to remove this shot, and any other debris, up the rebound section also. The aperture 71 may have a zig-zag entry 71a ig. 6 to prevent shot undesirably rebounding out of the treatment compartment.There may be a manually operable control flap 71b in entry 71 to control the flow of air and the direction of air flow or example to direct the airttowards the side regions of the compartment. Thus there could be three independently operable laterally adjacent flaps 73, 74, 75 (Fig. 2).

isan-holes in oil tanks are usually 24 inches (50.8cm) in diameter. It is desirable that the apparatus be capable of entry into such a tank but also in use treat a region of surface of a width greater than 24 inches (50.8cm). To this end the deliver channel and rebound section are welded together as at 80 and are welded to the top wall 62 to form unit 81. 3y detaching the delivery channel and rebound section at their flanges 82, 28, this unit 81 can be passed sideways through a manhole as the fore-and-aft dimension and height of the unit are less than 50.8cm.The remainder of the apparatus can be disassembled into units each, of which can pass through the man-hole for re-assembly of the apparatus in the tans for use therein.

The apparatus is normally powered b electric or hydraulic motors but can be manually moved on wheels 90 and would normally be used to treat surfaces such as metal, concrete, tarmacadam.

The rebound section may take other forms. For example the channels 21 may be formed by flat parallel partitions 90' in a rectangular housing 91' (Pig. 7). The rebound section may include flat parallel inclined walls 92 Fig. 8.

providing upward top mouths 93.

The curved section 26 in some cases may not be in the form of or provide separate channels but could be a manifold i.e. having a single inlet into which all the channels 21 deliver and having a single delivery mouth to the separator, extending across the machine.

The debris removed by device 32 may pass through a flexible conduit or pipe to a separator unit 100 Fig. 9 in which material entering at 101 is filtered out by filters 102 which are at intervals subjected to air pressure to dislodge the filtered debris into collecting hoppers 103.

In the present case augurs 104 extend into the hoppers and remove the material to a bagging location. This enables the hoppers to be emptied continuously, so that the treatment unit 10 can be used continuously without frequent stoppages to empty the hoppers 103.

In some cases the plates 65 may be present only on the sides of the machine and the outer seal 70 may in some circumstances be omitted from the front wall of the treat ment compartment.

The filter or sieve 47 could have a flat top.

Alternatively the mouth 48b could communicete with a pipe which extends forwards through a gap between channels 21 to a reception box at the front of the machine.

In some cases the mixture in receptacle 48 may pass or be passed through or in association with a magnetic device to remove the shot for re-use.

The filter 40 removes large debris, and the shot and other debris is carried to filter 45 which removes further debris and the smallest debris passes through filters 47, 50a. Some dust debris passes to device 32. The plate 44 can be held in a desired position of angular adjustment by clamp 44b in accordance with particular desired conditions of air flovr.

The impeller 11 may tend to direct sone shot wnaesirablz towards a wall of the channel 12 rather than to surface 19 and wear-resistant plates 120 may be fitted in side plates 121 bolted to the walls of channel 12. The plates 120 can be adjusted individually up or down in the plates 121 being held by screws 122 in adjusted position.

There mag be a plurality of plates 120 spaced along the channel their lateral projection into the channel (Fig. 12) being adjusted as found appropriate in operating circumstances. The plates 120 can be removed and replaced by fresh plates as required or desired.

It will be understood that the presence of weir 36 causes the mixture initially to largely flow laterally along the weir until the weir, which extends completely across the separation section, is full and the mixture then flows over the full width of the weir to give a curtain of mixture falling into the air stream in the gap 38. This assists in separating shot from debris. It will be noted that all the mixture is subjected to passage through one or more filters.

In a modification shovm in Fig. 14 a rubber seal 200 locates the rear part of a horizontal plate 201 held near its front by laterally spaced threaded bolts 202 engaged in fixed supports 203. The plate 201 carries a front flat upright flexible seal 204 e.g. of plastics, extending fully across the treatment compartment and rearwardly thereof one or more (three shown) straight brushes 205 extending fully across the compartment. A fixed steel plate 206 carrying a bottom flexible seal 207 defines air channel 208 with Szat 200 and the air flows into the treatment region along channel 209 between the surface 19 and the underface of the brushes and seal 204 thus giving a controlled flow close to the surface and the width of the compartment.The rate of flow can be adjusted by rotating bolt 202 to raise or lower plate 201 and thus the seal 204 and brushes 205.

Adjustment of bolts 202 enables the channel 209 to be higher at one side than the other if desired.

In the modification of Fig. 15 the lower end 210 of the delivery channel is tapered inwards in side view as the channel extends downwards to narrow the impact region X and.

the straight parts of the rebound channels 211 are of uniform cross section as shown.

In the arrangement of Figs. 16, 17 the delivery channel 12 is again tapered inwardly as it extends downwards and the reclaim or rebound section has channels 321 each of which diverges uniformly as seen in fore-and-aft section (Fig. 16) as it extends upwardly and converges uniformly as seen in fore-and-aft view (Fig. 17) the transverse cross-sectional area of each channel being uniform throughout its length or slightly increasing as the channel extends upwards. The total cross-section area at flange 29 equals the total input area of the curved part 26, which may be a single channel or four channels.

In the arrangements shown the inlet mouth of the rebound section is obstructed either by the internal baffles or the separate channels.

The curved part 26 could diverge upwards to assist in reducing the speed of the mixture of shot and debris.

Instead of shot other particulate abrasive can be used for example grit.

'he plates 121 can also be adjusted in or out on pin and slot mountings 121a. The plates 120 deflect some of the shot to reduce ang tendency for a side part of the area of surface being treated to receive more abrasion than the remainder, and with suitable adjustment of the plates 120 and 121 and the angular position on the impeller at which shot is fed to the impeller, a marginal portion at each side of the area being treated may receive lesser abrasion than the remainder, so that the adjacent marginal portions Y Fig 12 of to side by side passes of the machine may be overlapped without producing undesired abrasion or 'tracking' of surface 19 In the overlapped area.

Brushes 205 are dense and substantially nO air flows through the brushes into the treatment reion; the air flow is in channel 209 beneath the brushes 205 and the seal 204.

The surface 19 is horizontal or somewhat inclined but with suitable orientation of the delivery and rebound or reclaim sections in relation to the separation section upright or vertical surfaces could be treated.

Claims (2)

CItIMS

1. A method of treating a surface comprising hitting the surface with particulate material from a supply, replenishing the supply whilst effecting the method, and removing particulate material of less than a predetermined size.

2. A method as claimed in claim 1, in which the supply is replenished with particulate material of the largest size being used.