GB2160131A

GB2160131A - Hand-held blasting apparatus

Info

Publication number: GB2160131A
Application number: GB08514753A
Authority: GB
Inventors: William Robertson Macmillan
Original assignee: Tilghman Wheelabrator Ltd
Current assignee: Tilghman Wheelabrator Ltd
Priority date: 1984-06-15
Filing date: 1985-06-11
Publication date: 1985-12-18
Also published as: EP0165042A2; EP0165042A3; GB8415261D0; GB8514753D0

Abstract

A shot-blasting machine is dimensioned and adapted so that it can be hand-held by a worker during a shot blasting operation. The machine includes an abrasive throwing wheel assembly which is housed within a hood 10 both of which are preferably formed of a plastics material such as an elastomeric polyurethane. The hood has a peripheral opening 29 through which abrasive is directed by the throwing wheel assembly. A driving motor 31 external and to one side of the hood is connected to rotate the abrasive throwing wheel assembly. The other side of the hood is formed with an inlet 24 for the abrasive. Handles 28, 34 are preferably provided on both the hood and the driving motor to assist the worker in supporting and guiding the machine during operation. Abrasive is preferably fed to the shot blasting machine from an overhead abrasive supply system from which the machine is suspended by supporting cables or the like. The abrasive may be gravity fed to the shot blasting machine or it may be fed to the machine through a screw conveyor arrangement. <IMAGE>

Description

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SPECIFICATION Shot blasting machinery

5 This invention relates to shot blasting machinery and it is an object of the present invention to provide a shot blasting throwing wheel machine capable of being used in locations and/or for applications where a compressed air nozzle is con-10 ventionally employed to jet or impel abrasive against a surface or article to clean, surface finish or texture same. For convenience, the term "clean" will hereinafter and in the claims be solely employed.

15 Examples of such locations and/or applications are shot blast rooms, cleaning the exterior surfaces of buildings, metal tanks and other structures, cleaning floors, other ground areas, e.g. runways, and ships decks.

20 In each of the aforesaid a worker generally uses a high pressure air hose with an attached nozzle to blast abrasive against the surface or article to be cleaned. This entails the use of a relatively expensive air compressor together with its driving motor 25 and metal or reinforced delivery hose.

The use of a high pressure air hose is physically demanding since the worker has continuously to resist or react against forces arising out of reaction to the high pressure air striking the surface or arti-30 cle to be cleaned.

Moreover, a substantial amount of air and consequently power requires to be employed to deliver a relatively small poundage of abrasive.

In accordance with the aforesaid object, there-35 fore, the present invention provides a shot blasting machine dimensioned and adapted to be held by a worker during operation and comprising an abrasive throwing wheel assembly housed within a hood for directing abrasive out of a peripheral 40 opening in the latter, a driving motor external and to one side of the hood and connected to the abrasive throwing wheel assembly to rotate the latter, an abrasive inlet at the other side of the hood, and a handle connected to the machine for use by the 45 worker in supporting and guiding the machine during operation.

Preferably, the throwing wheel assembly and the hood of the hand-held shot blasting machine are of plastics construction as disclosed in United King-50 dom Patent Application No. 84 08808 filed 5th April 1984 (Publication No. 2 150 471A).

The throwing wheel assembly and/or the hood may have metal reinforcement but it is preferred that they are formed wholly of plastics. 55 Preferably, the plastics material is an elastomeric polyurethane which may be molecular bonded and which preferably has a hardness factor lying within the range A50 shore to D50 shore on the IRHD scale.

60 The throwing wheel assembly preferably comprises a unitary backplate, throwing blades and central impellor as disclosed in the aforesaid United Kingdom Patent Application.

The throwing wheel assembly also comprises a 65 control cage surrounding the impellor and an abrasive delivery tube or spout external of the hood, both preferably retained in position within and on the hood by releasable clamps.

The driving motor is preferably an electric motor of the kind used to operate drills or other small hand-held tools with its output shaft bolted or otherwise secured to the backplate through the centre of the impellor.

The driving motor preferably incorporates a handle at its end remote from the output shaft.

A handle is preferably connected to the hood at the abrasive feed side adjacent its periphery at a region remote from its abrasive outlet opening.

Both handles are preferably provided.

The hood handle is preferably carried by a flanged plate adapted to close an open side of the hood through which the throwing wheel assembly can be inserted and removed.

Preferably this plate is apertured to accept the abrasive feed tube and carries the aforesaid releasable clamps.

The hood may have removably attached to it at its abrasive outlet opening a nozzle.

Preferably there may be more than one nozzle to permit different abrasive spray patterns to be achieved.

The hood at the driving side preferably has an access opening closable by a removable plate traversed by the driving connection between the backplate and driving motor.

Preferably, a bridging member is secured to and extends between the hood and the driving motor casing, an eyebolt from the bridging member for attachment to a cable of a spring tension counterbalance device adapted to be suspended from a fixed structural element. By this means, the weight of the hand-held shot blasting machine is supported so that the worker is mainly concerned with directing and moving the machine over a convenient working area.

The spring tension of the counterbalance device is adjustable.

Preferably, two such bridging members are provided between the hood and driving motor casing and are disposed parallel one with another and each is adapted to receive the eyebolt.

Preferably, the abrasive feed tube or spout is adapted to be gravity fed with abrasive from a hopper by a feed hose constructed or constrained to have an angle of repose of at least 35°.

A preferred construction of feed hose is one of coiled configuration with the coils pre-set to always lie at an angle of at least 35°.

Another possible feed hose construction is one of a bellows configuration.

Another abrasive feed system, especially but not exclusively adapted for use when the shot blasting machine is used in a shot blast room, comprises an overhead screw conveyor delivery arrangement having an outlet delivery tube or pipe flexibly connected to the abrasive feed tube or pipe of the shot blasting machine.

Preferably, the abrasive feed system comprises an upright screw conveyor housed in a tube or casing which, at its lower end, is in communication

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with an abrasive supply hopper, and an overhead, generally horizontally extending screw conveyor also housed in a tube or casing with the tubes or casing being in communication to permit abrasive 5 flow from the upright tube to the horizontal tube.

Preferably, each screw conveyor is independently driven by a geared motor.

Preferably, the upright tube is vertical and has a lower stationary section and an upper section ro-10 tatable relative to the lower section, the horizontal tube being connected to the upper vertical tube section.

Preferably, the horizontal tube is pivotaily mounted on the upper vertical tube section for 15 movement about a horizontal axis.

Preferably, the horizontal tube and upper vertical tube section are interconnected by gas (or other compressible fluid) strut means serving to maintain or restore a generally right angled disposition 20 between the horizontal tube and the vertical tube. It is possible that an equivalent mechanical spring arrangement or gas (fluid)' mechanical spring arrangement may be employed for this purpose.

The horizontal tube, at one end, incorporates a 25 surge (or storage) hopper from which extends downwardly the outlet delivery pipe.

The outlet delivery pipe, which is of wear resistant metal, is preferably secured to the surge hopper outlet by a flexible tubular joint and is 30 connected to the abrasive feed tube of the shot blasting machine also by a flexible tubular joint.

The shot blasting machine is preferably connected to the surge hopper horizontal tube by a cable to eliminate unnecessary weight of the delivery 35 pipe. The cable is preferably a steel cable.

The geared motor for the vertical screw conveyor is preferably supported at the top of the vertical tube.

The geared motor for the horizontal screw con-40 veyor is preferably supported at the end of the horizontal tube remote from the surge hopper and may act as a counterbalance weight for the pivoting action of the horizontal tube.

A counterbalance weight may be connected to 45 the horizontal tube at or adjacent its surge-hopper remote end.

A feature of the hand-held shot blasting machine is that the hood control cage and feed tube can be pivoted, using the handle on the hood, about the 50 impellor to spray the thrown abrasive along a predetermined path.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 55 Figure 1 is a side elevation of a hand-held shot blasting machine according to the invention;

Figure 2 is a corresponding plan view;

Figure 3 is a detail view of part of Fig. 2 to an enlarged scale;

60 Figure 4 is a diagrammatic view of a worker operating the machine;

Figures 5 and 6 illustrate two of many possible applications of use of the hand-held shot blasting machine; and 65 Figure 7 is a diagrammatic view of an abrasive supply arrangement for the hand-held shot blasting machine, especially suitable for when the latter is used in a shot blast room.

The hand-held shot blasting machine comprises a plastics hood 10 housing a plastics abrasive throwing wheel assembly 11.

The plastics used to produce the hood and wheel assembly is a molecular bonded elastomeric po-lyurethane having a hardness factor within the range A50 Shore to D50 Shore on the IRHD scale.

The abrasive throwing wheel assembly 11 comprises a backplate 12 with integral throwing blades 13 and an integral central vaned impellor 14.

The hood 10 has on one side an access opening 15 closed by a removable plate 16 bolted or screwed in position as indicated at 17.

At its other side the hood 10 is wholly open to permit insertion and removal of the throwing wheel assembly 11, which opening is closed by a flanged plate 18 secured to the hood periphery by bolts or screws 19. The flanged plate 18 has a central aperture 20 through which can be inserted or removed a plastics control cage 21 lipped at 22 to rest on an annular ledge 23 of the flanged plate 18.

A plastics abrasive feed tube 24 outwardly flanged at 25 at one end bears at its flange on the lip 22 and the control cage 21 and feed tube 24 are held in position in and on the flanged plate 18 of the hood 10 by clamp elements 26 bolted to the flanged plate 18 as at 27.

A handle 28 is secured to the flanged plate 18 and extends normally outwardly therefrom parallel with the axis of rotation of the throwing wheel assembly 11 and diametrically opposed to the abrasive outlet opening 29 of the hood 11.

A nozzle 30 is a push fit over the hood 10 at the outlet opening 29 to give a controlled spray pattern to the egressing abrasive. There may be a number of differently shaped nozzles to permit different spray patterns to be achieved dependent upon the cleaning work being carried out.

An electric driving motor 31 has its output shaft 32 coupled (bolting or otherwise) as indicated at 33 to the backplate 12 at the centre of the impellor 14.

The driving coupling 33 traverses the access plate 16 which acts as a bearing for the throwing wheel assembly 11.

The driving motor 31 has a casing terminating in a handle configuration 34 disposed normally to the handle 28.

The hood 10 and driving motor 31 are connected by two parallel bridge members 35 bolted to the hood 10 and driving member at 36.

At right angles to each bridge member 35 is an internally screw-threaded stem 37.

In Fig. 1, one stem 37 (the lower) is closed by a bolt 38, i.e. it is not in use, while the other stem 37 (the upper) receives and mounts an eye-bolt 39.

This eye-bolt 39 is adapted to have secured to it a reeled cable 40 of a spring tension counterbalance device 41 suspended by a cable 42 to a fixed structure element, see arm 43 of Figs. 5 and 6 secured to an abrasive supply hopper 44.

This counterbalance device 41 supports the weight of the hand-held shot blasting machine so

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that a worker W (Fig, 4) needs only to move and direct the machine over the area being cleaned at any instant.

Abrasive is fed by gravity from a storage hopper 5 such as 44 supported above the worker W via a feed or supply hose 45 which has an angle of repose never less than 35° and which connects the hopper outlet to the feed tube 24 of the shot blasting machine.

10 A preferred construction of supply hose is a permanently coiled hose 46 (see Fig. 4) whereof the coils are pre- set so that they can never take up an angle less than 35° irrespective of the relative dispositions of the hopper 44 and the shot blasting 15 machine.

This shot blasting machine can deliver much larger quantities of abrasive for much less power in the same time than an equivalent compressed air hose abrasive delivery system without impos-20 ing any physical hardship on the worker, i.e. no reaction necessary to forces resulting from high pressure air blast on surface or article being cleaned.

An example of usage where the shot blasting 25 machine of the present invention has considerable advantages over a compressed air shot blasting system is in the cleaning of the exterior walls of buildings, or in a conventional air operated shot blast room.

30 Conventionally in cleaning walls of buildings, a wall to be cleaned is covered with scaffolding and the aforesaid expensive and excessive power consuming air compressor/motor combination is used to impel the abrasive against the wall to be 35 cleaned.

With the present invention, however, a hopper 44 loaded with abrasive is mounted on an elevata-ble platform 47 (see Fig. 5). The worker stands on the platform 47 which will be provided with some 40 front shielding for the worker and with the platform 47 at its upper level the worker shot blasts the area of wall WL immediately in front of him. The platform 47 is then lowered in a series of steps until an area of wall WL extending the height of 45 the building and of a predetermined width is cleaned. The platform 47 which is mounted on a vehicle 48 is then moved to an uncleaned area of wall WL immediately adjacent to the cleaned area and the vertical step-wise cleaning process is re-50 peated. This is done until the whole wail area is shot blasted cleaned.

Another example of cleaning where the shot blasting machine of the present invention has considerable advantages over an air pressure shot 55 blasting system is shown in Fig. 6 where a bridge B is being cleaned using the simple platform 47 and hopper 44 arrangement of Fig. 5.

In the case of a shot blast room, an abrasive supply system which is especially but not exclu-60 sively suitable for use with such blast rooms, is shown in Fig. 7.

The supply system comprises a floor mounted storage hopper 50 for abrasive in communication with the lower end of a vertical steel tube 51 hous-65 ing a vertical screw conveyor 52.

The steel tube comprises a lower stationary section 51A and an upper section 51B rotatable about the tube axis through an angle usually 180° but possibly less (see arrow A). It may, of course be rotatable through 360°.

The tube sections 51A and 51B are connected by a conventional rotary joint 53 with the tube section 51B being freely rotatable.

The vertical screw conveyor 52 is driven by a geared electric motor 54 supported at the top of the rotatable tube section 51B. The latter has a branch tube 55 to provide an abrasive outlet by the tube 51 and to direct abrasive downwardly to a horizontal steel tube 56.

The horizontal tube 56 has an abrasive inlet indicated at 57 and houses a horizontal screw conveyor 58.

The horizontal tube 56 lies to one side of the rotatable tube section 51A and is connected to same by a conventional horizontal pivotal joint arrangement 59 which permits free pivotal movement of the horizontal tube 56 in a vertical plane (see arrow B).

The horizontal tube 56 has a major length extending to one side of the vertical tube 51 and a minor length extending to the other side. A geared electric motor 60 for driving the horizontal screw conveyor 58 is supported on the end of said minor length.

The other end of the horizont tube 56 terminates in a surge or storage hopper 61.

A gas strut 62 (or more than one) interconnects the horizontal tube 56 and the rotatable tube section 51B and serves to maintain and generally restore the right-angled disposition of the horizontal and vertical tubes 56, 51. It also serves to prevent abrupt movements of the horizontal tube 56, i.e. it acts as a damper.

The gas strut 62 serves to support the weight of the major overhanging length of the horizontal tube 58 and this support is assisted by the geared motor 60 which acts as a counterbalance weight. If necessary, a separate or additional counterbalance weight can be provided.

The horizontal screw conveyor 58 delivers abrasive into the surge hopper 61 which has a bottom outlet to which is connected a steel delivery tube 62, which may be formed of other abrasive wear-resistant material. The delivery tube 62 is connected by conventional flexible joints 63, 64 respectively to the outlet of the surge hopper 61 and to the feed tube 24 of the hand-held shot blasting machine 65.

As the overhanging horizontal tube 56 and its external screw conveyor 58 are freely rotatable about a vertical axis and freely pivotal about a horizontal axis the worker handling the shot blasting machine can easily and readily move around the shot blast room or other working area.

To alleviate unnecessary weight on the delivery tube 62 the hand-held shot blasting machine 65 is suspended from the surge hopper 61, or possibly the horizontal tube 56, by one or more steel cables 66 (two shown).

It will be manifest that the height and length of

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the tubes 51, 56 will be determined by the particular working application involved.

The supply system need not be floor mounted. It may, for example, alternatively be suspended 5 from, say, an overhanding beam.

The supply system is preferably an open flow system but, if necessary or desirable, control valves, preferably electrically operated, may be fitted, say, at the outlet of branch tube 55 and/or the 10 outlet of surge hopper 61.

It is envisaged that the shot blasting machine of the present invention can be dimensioned so that it can be held in one hand thus permitting its use in a blast cabinet, the worker being external to the 15 latter and the machine being inserted by the worker through a protective transparent curtain or similar.

The shot blasting machine may be employed in the cleaning of any kind of structure whatever the 20 latter is made from, for example steelwork, brickwork and stonework.

In a modification the throwing wheel is not bi-di-rectional, as is disclosed in our aforesaid United Kingdom Patent Application. Its blades may have 25 only a single throwing face, the other blade face having strengthening or reinforcing formations thereon or associated therewith.

In another modification the shot blasting machine has a single hoop-like handle for manipula-30 tion and/or directing purposes.

The throwing wheel assembly may, of course, be fabricated from steel or cast in abrasive-resistant metal, and in either case can be bi-directional or uni-directional.

35 While the shot blasting machine is designed so that it can be held by a worker during operation, it is visualised that it can instead be operated by a robot or other mechanical/electrical device.

Claims

40 CLAIMS

1. A shot blasting machine dimensioned and adapted to be held by a worker during operation and comprising an abrasive throwing wheel as-

45 sembly housed within a hood for directing abrasive out of a peripheral opening in the latter, a driving motor external and to one side of the hood and connected to the abrasive throwing wheel assembly to rotate the latter, an abrasive inlet at the 50 other side of the hood, and a handle connected to the machine for use by the worker in supporting and guiding the machine during operation.

2. A machine as claimed in claim 1, in which the throwing wheel assembly and the hood are

55 formed of a plastics material.

3. A machine as claimed in claim 2, in which the throwing wheel assembly and/or the hood have metal reinforcement.

4. A machine as claimed in claim 1 or 2, in

60 which the plastics material is an elastomeric polyu-rethane which may be molecular bonded and which preferably has a hardness factor lying within the range A50 Shore to D50 Shore on the IRHD scale.

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5. A machine as claimed in any one of Claims 1

to 4, in which the throwing wheel assembly comprises a unitary backpe, throwing blades and central impellor.

6. A machine as claimed in claim 5, in which the throwing wheel assembly also comprises a control cage surrounding the impellor and an abrasive delivery tube or spout external of the hood.

7. A machine as claimed in claim 6, in which the impellor and the delivery tube are retained in position within and on the hood by releasable clamps.

8. A machine as claimed in any one of claims 5 to 7, in which the driving motor is an electric motor of the kind used to operate drills or other small hand-held tools with its output shaft secured to the backplate through the centre of the impellor.

9. A machine as claimed in claim 8 in which the driving motor incorporates a handle at its end remote from the output shaft.

10. A machine as claimed in any one of claims 1 to 9, in which a handle is connected to the hood at the abrasive feed side adjacent its periphery at a region remote from its abrasive outlet opening.

11. A machine as claimed in claim 10, in which the hood handle is carried by a flanged plate adapted to close an open side of the hood through which the throwing wheel assembly can be inserted and removed, releasable clamps being provided to retain the flanged plate in position.

12. A machine as claimed in claim 11, in which the flanged plate is apertured to accept the abrasive feed tube and carries the releasable clamps.

13. A machine as claimed in any one of claims 1 to 12, in which the hood has removably attached to it at its abrasive outlet opening a nozzle.

14. A machine as claimed in claim 13, in which there is more than one nozzle, each differently configured, to permit different abrasive spray patterns to be achieved.

15. A machine as claimed in any one of claims 5 to 14, in which the hood at the driving side has an access opening closable by a removable plate traversed by the driving connection between the backplate and driving motor.

16. A machine as claimed in any one of claims 8 to 15, in which a bridging member is secured to and extends between the hood and the driving motor casing, an eyebolt from the bridging member for attachment to a cable of a spring tension counterbalance device adapted to be suspended from a fixed structural element.

17. A machine as claimed in claim 16, in which two bridging members are provided between the hood and driving motor casing and are disposed parallel one with another and each is adapted to receive the eyebolt.

18. A shot blasting system comprising a handheld shot blasting machine as claimed in any one of claims 1 to 17, connected to an abrasive storage hopper by an abrasive delivery tube communicating with the hood abrasive inlet.

19. A system as claimed in claim 18, in which the storage hopper is disposed at a location above the shot blasting machine with the delivery tube being adapted to gravity feed abrasive from the

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hopper to the feed tube or spout of the shot blasting machine.

20. A system as claimed in claim 19, in which the delivery tube is constructed or constrained to

5 have an angle of repose of at least 35°.

21. A system as claimed in claim 20, in which the delivery tube is of coiled construction with the coils preset to be at an angle of at least 35°.

22. A system as claimed in claim 19, in which

10 the delivery tube is of bellows configuration.

23. A system as claimed in any one of claims 19 to 22, comprising a suspension arrangement for supporting the shot blasting machine from the overhead hopper or other overhead structure.

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24. A system as claimed in claim 23, in which the suspension arrangement is a spring tension counterbalance device having a cable connected to the overhead hopper or other structure and to the shot blasting machine.

20 25. A system as claimed in claim 18, in which the storage hopper is connected to an overhead screw conveyor delivery arrangement having an outlet delivery tube or pipe flexibly connected to the abrasive feed tube or pipe of the shot blasting

25 machine.

26. A system as claimed in claim 25, comprising an upright screw conveyor housed in a tube or casing which, is in communication with an abrasive at its lower end supply hopper, and an over-

30 head, generally horizontally extending screw conveyor also housed in a tube or casing with the tubes or casing being in communication to permit abrasive flow from the upright tube to the horizontal tube.

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27. A system as claimed in claim 26, in which each screw conveyor in independently driven by a geared electric motor.

28. A system as claimed in claim 26 or 27, in which the upright tube is vertical and has a lower

40 stationary section and an upper section rotatable relative to the lower section, the horizontal tube being connected to the upper vertical tube section.

29. A system as claimed in claim 28, in which the horizontal tube is pivotally mounted on the up-

45 per vertical tube section for movement about a horizontal axis.

30. A system as claimed in claim 28 or 29, in which the horizontal tube and upper vertical tube section are interconnected by gas (or other com-

50 pressible fluid) strut means serving to maintain or restore a generally right angled disposition between the horizontal tube and the vertical tube.

31. A system as claimed in any one of claims 26 to 30, in which the horizontal tube, at one end,

55 incorporates a surge (or storage) hopper from which extends downwardly the outlet delivery pipe.

32. A system as claimed in claim 31, in which the outlet delivery pipe is secured to the surge

60 hopper outlet by a flexible tubular joint and is connected to the abrasive feed tube of the shot blasting machine also by a flexible tubular joint.

33. A system as claimed in claim 32, in which the shot blasting machine is connected to the

65 surge hopper or horizontal tube by a cable to eliminate unnecessary weight of the delivery pipe.

34. A shot blasting machine and/or a shot blasting system, substantially as hereinbefore described with reference to the accompanying drawings.

Printed in the UK for HMSO, D8818935,10/85, 7102.

Published by The Patent Office, 25 Southampton Buildings, London,

WC2A 1AY, from which copies may be obtained.