GB2063116A

GB2063116A - Rotary impeller wheel for blast cleaning apparatus

Info

Publication number: GB2063116A
Application number: GB7939172A
Authority: GB
Original assignee: Auto Alloys R&D Ltd
Current assignee: Auto Alloys R&D Ltd
Priority date: 1979-11-13
Filing date: 1979-11-13
Publication date: 1981-06-03
Also published as: EP0029346A1; GB2063116B

Description

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GB 2063116 A

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SPECIFICATION

Improvements in or relating to rotary impeller wheels for a blast cleaning apparatus

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The invention is concerned with improvements in or relating to rotary impeller wheels for blast cleaning apparatus and the components of such wheels.

In one conventional kind of blasting apparatus a 10 rotary impeller wheel is located within a housing. Metallic abrasive or other cleaning material is fed to the centre of the wheel in an axial direction and discharged radially under centrifugal action as the wheel rotates. A control member or control cage is 15 located around the central hub of the wheel and has a peripheral opening through which the cleaning material is discharged. The control cage is rotatable relative to the wheel hub in order to alter the direction of discharge of the cleaning material. 20 The rotary impeller wheel includes radially extending blades which are subject to considerable wear and thus require frequent replacement. It is convenient to be able to replace the blades by removing the control cage, removing the worn blades through 25 the central aperture and inserting replacement blades through the aperture, as this does not therefore require dismantling of any of the components of the housing.

According to the present invention there is pro-30 vided a blade mounting plate for a rotary impeller wheel, the plate comprising a centrally located through aperture, and, in one side face of the plate, and opening on to said face, a plurality of radially extending slots, each of which opens at one end into 35 the aperture, and has such a cross section that the side face opening has a lateral dimension less than a corresponding internal dimension, whereby a blade having a cross section substantially complementary to that of the slots can be retained in a respective slot 40 when one side edge of the blade is entered from the central aperture through the open end of the slot.

Preferably the other end of each slot terminates short of the radially outermost edge of the plates.

Preferably also means are provided for biasing the 45 blade in a direction parallel to the axis of the plate into intimate engagement with internal walls of the slot. The biasing means may comprise a recess formed in the base of each slot for receiving a biasing spring.

*50 In one arrangement the slots may be arranged in diametrically opposed pairs on said one side face of the plate. In an alternative arrangement the slots may be arranged such that each is diametrically opposed to a location intermediate another pair of 55 slots.

On said one side face of the plate, the slots extend over an area which may be of substantially truncated conical cross section, terminating in a raised edge at the central aperture.

60 According to the present invention there is also provided a rotary impeller wheel comprising a blade mounting plate as described in any of the five preceding paragraphs, and at least one blade, one side edge of which has a cross section complemen-65 tary to that of the slots.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:-

Figure 1 is a sectional front elevation of a blast cleaning apparatus;

Figure 2 is a plan view of a blade mounting plate for use in a rotary impeller wheel according to one embodiment of the invention;

Figure 3 is a section on X-X of Figure 2;

Figure 4 is a side view of a blade for use with the blade mounting plate of Figures 2 and 3;

Figure 5 is an end view of the blade of Figure 4;

Figure 6 is a plan view of a blade mounting plate for a rotary impeller wheel according to a second embodiment of the invention;

Figure 7 is a section on A-A of Figure 6;

Figure 8 is a side view of a plate for use with the blade mounting plate of Figures 6 and 7; and

Figure 9 is an end view of the blade of Figure 8

Referring to Figures 1 to 5 of the drawings an airless blast cleaning apparatus, i.e. an apparatus wherein the abrasive cleaning medium is thrown by mechanical means, eliminating the need for compressed air, includes a rotary impeller wheel 10 mounted on the end of a rotatable shaft 12 by means of a hub assembly 14. The wheel 10 includes a central impeller 16 of cage-like construction and a series of radially extending blades 18 secured on a blade mounting side plate 20 as hereinafter described. A control cage 22 surrounds the impeller 16 and is angularly adjustably mounted on an external housing 24 enclosing the wheel 10. The control cage 22 is provided with a peripheral opening the position of which relative to the impeller wheel 16 determines the direction of which the abrasive cleaning medium is directed out of the apparatus during operation. The abrasive medium is introduced into the impeller wheel 10 by means of a feed chute assembly 26 mounted on a supporting bracket 28.

The side plate 20 (Figures 2 and 3) is of circular configuration having a centrally locatedthrough aperture 30. On one side face 32 of the plate 20, i.e. the face on which the blades 18 are mounted, there are provided a plurality of radially extending slots 34 which are arranged in diametrically opposed pairs. Each slot 34 opens at its top on to the face 32 and also opens at a radially inner end on to the central aperture 30. The cross section of each slot 34 is substantially of dovetail shape such that side walls 36 extend in converging paths from a base 38 of the slot with the width of the base 38 being greater than the width of the open top. Each slot 34 terminates at its radially outermost end short of the peripheral edge of the plate 20 and is provided in its base 38 with a substantially rectangular recess 40 for receiving a compression spring (not shown) for a purpose hereinafter described.

On the opposed face 42 the plate 20 is formed as a circular recess 44 for receiving a respective part of the hub assembly 14, the plate 20 being secured to the hub assembly 14 by means of screws 46 (Figure 1) extending through the hub assembly 14 into fixing holes 48 on the plates 20.

Each of the blades 18 (Figures 4 and 5) is of substantially rectangular shape formed of a wear

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resistant material, and has its opposed side faces identical. At one side edge, each ofthe blades 18 has a mounting lug 50 extending along the length ofthe blade 18 over a distance corresponding to the length 5 ofthe slots 34. The lug 50 has a cross section complementary to that of the slots 34 such that the lug 50 can enter a respective one ofthe slots 34 from the aperture 30 in to the open end of the slot 34, and be held against removal from the slot 34 in a 10 direction parallel to the axis ofthe plate 20. When a spring is located in the recess 40 of the slot 34, the blade 18 is biased into intimate contact with the inner faces ofthe walls 36 ofthe slot 34 to be frictionally retained against movement out of the 15 slot 34 in a radial direction.

As the blade 18 is longerthanthe lug 50, the blade 18 overlies a peripheral rim ofthe plate 20 when the lug 50 is moved wholly within the slot 34. The blade 18 at said one side edge is provided with a laterally 20 extending lip 52 on each face, each lip 52 being angled from the radially innermost end ofthe blade 18 to terminate in a maximum height at the radially outermost end ofthe blade 18. The lips 52 enable a radiused surface to be formed at each face ofthe 25 blade 18for increased wear resistance atthe junction between the blade 18 and the plate 20. The other side edge ofthe blade 18 has a cross section defining laterally extending lips 54 to assist in the directing of the abrasive medium.

30 This embodiment is suitable for impeller wheels of diameters up to 15 inches where the length ofthe blades is less than the diameter ofthe central aperture, such that, with the control cage removed, worn blades can be removed and replacement 35 blades provided by sliding ofthe blades in the slots via the central aperture. For impeller wheels which are over 15 inches in diameterthe length ofthe blade is greater than the diameter ofthe central aperture and therefore such removal and replacement of 40 blades is not possible. The second embodiment as shown in Figures 6 to 9 is provided to achieve this possibility.

In the second embodiment, the blade mounting plate 20' is of circular configuration having a central 45 through aperture 60. One face 62 ofthe plate 20', i.e. that face on which the blades 18 are mounted, is provided with a plurality of radially extending slots

64 which are of identical configuration to the slot 34 ofthe first embodiment but of different dimensions,

50 resulting from the different sizes of wheel being used. Like references have therefore been used to denote other like features. Each slot 64 is arranged to be diametrically opposed to a location intermediate of two other adjacent slots 64 for a purpose hereinaf-55 ter described.

The plate 20' has a cross section which, in an area

65 over which the slots 64 extend, is of truncated conical section terminating in an edge ofthe aperture 60 raised above the peripheral rim. As in the first

60 embodiment the slots 64 terminate at their radially outermost ends short ofthe peripheral edge ofthe plate.

Each ofthe blades 18' (Figures 8 and 9), provided for the second embodiment, is of substantially 65 rectangular configuration having its opposed faces identical. One side edge, i.e., that edge to be mounted on the plate 20 - is provided with a mounting lug 70 which is complementary in cross section to the slots 64 and which extends at an angle 70 relative to the side edge ofthe blade 18' corresponding to the cone angle ofthe area ofthe face 62. That end ofthe lug 70 which is radially outermost in use is provided with a flat 72 extending parallel to the edge ofthe blade 18' for a purpose hereinafter described. 75 A lip 74 is provided on each face ofthe blade 18' at said one edge to extend from a location along the lug 70 to the end of the blade 18' which overlies the peripheral rim ofthe plate 20' in use. The lips 74 enable radiused surfaces to be provided at the 80 connection ofthe blades 18' and the plate 20'. The other side edge ofthe blade 18' is of similar configuration to the corresponding side edge ofthe 4 blade 18 ofthe first embodiment.

In use, a blade 18', although of longer length than 85 the diameter of the aperture 60, can enter the open end of a respective one of the slots 64 via the aperture 60. The raised edge ofthe aperture 60 and the corresponding angles ofthe slot 64 and the lug 70 enable the respective end ofthe lug 70 to enter 90 the slot 64 while the other end ofthe lug 70 remains clear ofthe edge ofthe aperture 60 atthe diametrically opposed location. Also the flat 72 facilitates the entry ofthe lug 70 into the slot 64. As each slot 64 is not diametrically opposed to any other slot 64, a 95 blade 18' can be removed and replaced even when blades are already positioned in the other slots.

The plate 20' also has a circular recess in its other side face and mounting holes for attachment ofthe plate to the hub assembly. Again these features are 100 similar to those ofthe first embodiment and like numerals therefore refer to like parts.

An arrangement according to the invention is advantageous in that a single sided impeller wheel is easier and cheaper to manufacture than the conven-105 tional double sided wheels. Also the rotating mass is reduced and therefore less power is required at start-up ofthe machine. Further renewal and replacement of blades is possible for impeller wheels of any diameter and this is particularly advan-110 tageous in that dismantling of housings or hoods for the impeller wheels is not required when replacement ofthe blades becomes necessary. The blades • are conveniently retained in their slots against both axial and radial movement in use and the impeller 115 wheels can be adapted to fit any existing blast < cleaning machine with a suitable arrangement of mounting holes. It is envisaged that different arrangements of mounting holes are provided on each blade mounting plate for this purpose.

120 It is also to be appreciated that the components are made of a wear resistant material where appropriate and all connecting edges are rounded off where possible.

Various modifications may be made without de-125 parting from the invention. For example the means for retaining the blades in the slots by friction may be other than that described, while the blades and slots may be of a configuration other than that shown.

130 Whilst endeavouring in the foregoing specification

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to draw attention to those features ofthe invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of 5 features hereinbefore referred to whether or not particular emphasis has been placed thereon.

Claims

10 1. Apparatus for use in a rotary impeller wheel, said apparatus comprising a plate member having a centrally located through aperture, and, in one side face ofthe plate member, and opening on to said one side face, a plurality of radially extending slots,

15 each of which opens at one end into the aperture, and has such a cross section that the side face opening has a lateral dimension less than a corresponding internal dimension, whereby a blade member, at least part of one side edge of which has a

20 cross section substantially complementary to that of the slots, can be retained in a respective slot when said part of said one side edge ofthe blade member is entered from the central aperture through the open end ofthe slot.

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2. Apparatus according to claim 1, wherein the other end of each slot terminates short of the radially outermost edge ofthe plate member.

3. Apparatus according to claim 1 or 2, wherein means are provided for biasing the blade members

30 in a direction parallel to the axis ofthe plate member into intimate engagement with internal walls ofthe slot.

4. Apparatus according to claim 3, wherein the biasing means comprises a recess formed in the

35 base of each slot for receiving a biasing spring.

5. Apparatus according to any ofthe preceding claims, wherein the slots are arranged in diametrically opposed pairs on said one side face ofthe plate member.

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6. Apparatus according to any of claims 1 to 4, wherein the slots are arranged such that each is diametrically opposed to a location intermediate another pair of slots.

7. Apparatus according to claim 6, wherein, on

45 said one side face ofthe plate member, the slots extend over an area which has a substantially truncated conical cross section, terminating in a raised edge at the control aperture.

8. Apparatus for use in a rotary impeller wheel,

• 50 said apparatus comprising a blade member, at least part of one side edge of which has a cross section wherein an inner portion has a lateral dimension less than an outer portion, whereat, the blade member can be retained in a respective one of a plurality of

55 radially extending slots each formed in one side face of a plate member and having a cross section substantially complementary to that of said one side edge part ofthe blade member.

9. Apparatus according to claim 8, wherein said

60 part of said one side edge comprises a lug which extends from one end only partly along said one side edge.

10. Apparatus according to claim 8 or 9, wherein said part of said one side edge at an angle relative to

65 the longitudinal dimension ofthe blade member.

11. Apparatus according to claim 10, wherein one end of said part of said one side edge has a flat extending parallel to the longitudinal dimension of the blade member.

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12. Apparatus according to claim 10 or 11, when dependent on claim 9, wherein a lip is provided on each side face ofthe blade member to extend from a location along said lug to the end ofthe blade member extending beyond the lug. 75

13. Apparatus according to claim 9, wherein a lip is provided on each side face ofthe blade member, and is angled from said lug at said one end of said one side edge to a location spaced from said lug to the end ofthe blade member extending beyond the 80 lug.

14. Apparatus according to any of claims 8 to 13, wherein an opposite side edge ofthe blade member has a cross section defining laterally extending lips.

15. A rotary impeller wheel comprising a plate 85 member according to any of claims 1 to 7, and at least one blade member according to any of claims 8 to 14, each ofthe slots in the plate member having a cross section substantially complementary to the cross section of said part of said one side edge ofthe 90 blade member.

16. A plate member for use in a rotary impeller wheel substantially as hereinbefore described with reference to Figures 2 and 3 or Figures 6 and 7 ofthe accompanying drawings.

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17. A blade member for use in a rotary impeller wheel substantially as hereinbefore described with reference to Figures 4 and 5 or Figures 8 and 9 ofthe accompanying drawings.

18. Any novel subject matter or combination 100 including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any ofthe preceding claims.

Printed for Her Majesty's Stationery Office by Croydon Printing Company Limited, Croydon, Surrey, 1981.

Published by The Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.