EP0084430A1

EP0084430A1 - Improvements in or relating to shot blast machinery

Info

Publication number: EP0084430A1
Application number: EP83300143A
Authority: EP
Inventors: William Robertson Macmillan
Original assignee: Tilghman Wheelabrator Ltd
Current assignee: Tilghman Wheelabrator Ltd
Priority date: 1982-01-16
Filing date: 1983-01-12
Publication date: 1983-07-27
Also published as: GB2113127A; DE3364555D1; GB8300758D0; GB2113127B; ATE20845T1; EP0084430B1

Abstract

A lining assembly for a hood for housing an abrasive throwing wheel comprises two end wearplates, two side wearplates of unitary or split construction, and an upper wearplate with integral sides, all butted together to provide locating and labyrinthal joints and with each end wearplate being formed with at least one inwardly-directed wear projection or dam adapted to intervene in the flow path of abrasive accelerating around the hood thereby substantially to reduce the rate of wear on the wearplates by the abrasive.

Description

This invention relates to shot blast machinery and is particularly concerned with the wheel hood linings of such machinery.
A wheel hood lining, as is well known to those skilled in the art, consists of a multiplicity of wearplates which are assembled together inside a wheel hood to surround a rotatable abrasive throwing wheel to protect the wheel hood from attack by the abrasive.
These wearplates are formed of hard metal to give them a reasonably long working life but eventually they become worn and require replacement. An example of hard metal, which is a term well known to those familiar with the shot blast machinery industry, is that sold by the Applicants under the Trade Mark "Blastlyfe" which is a high chrome alloy. They constitute a significant part of the "spares" business in shot blast machinery.
An example of a typical wheel hood lining, say, for a wheel hood for accommodating a 19½ inch diameter throwing wheel consists of upper and lower end wearplates (two sets), right and left hand side wearplates (two sets), upper side wearplates (two) and an upper wearplate (one), i.e. 11 separate wearplates which require to be assembled together to provide the hood lining and 6 separate patterns are necessary to manufacture these 11 wearplates by casting.
It will be manifest that this assembly of wearplates provides many joints through which abrasive might leak so causing wear in the wheel hood and thus necessitating maintenance and eventual replacement with consequent cost to the user. Also, the need to provide 6 patterns to produce the wearplates for the assembly of the 11 part lining increases the cost of production and again involves the user in relatively high costs.
It is an object of the present invention to provide a wheel hood lining which has a longer life, costs less to produce, and significantly reduces maintenance time and costs when compared with existing wheel hood linings.
According to one aspect of the present invention we provide a wheel hood lining consisting of two end wearplates, two side wearplates and an upper. wearplate with integral sides.
This means a lining consisting of only 5 wearplates with a need to produce only 3 patterns to produce the wearplates by casting.
In an alternative construction of wheel hood lining each side wearplate consists of two halves.
Even with this construction the lining consists of only 7 wearplates but still requires only 3 patterns to produce the wearplates by casting.
In most applications these wearplates will all be of hard metal but in some lower-powered applications the side wearplates (2 or 4 halves) may be made of white iron.
According to a second aspect of the present invention we provide a wheel hood lining including an end wearplate formed with at least one inwardly-directed projection adapted to intervene in the flow path of abrasive accelerating around the hood thereby substantially to reduce the rate of wear on said end wearplate by the abrasive.
Preferably also the projection serves to direct such abrasive back into the normal abrasive pattern of the throwing wheel and eliminates abrasive rebound into the hood thus increasing blasting efficiency.
There are preferably two or more such inwardly-directed formations spaced alongthe length of the end wearplate.
The projections or "dams" as they will hereinafter be called for convenience may in the assembled lining extend horizontally inwards of the end wearplate, or they may be directed upwardly and inwardly, or downwardly and inwardly. This last configuration would most readily facilitate diversion of the abrasive into the throwing wheel abrasive pattern.
It will be manifest that, with both end wearplates provided with such wear dams, the wear dams of the leading end wearplate in terms of direction of wheel rotation (i.e. the lefthand end wearplate for a clockwise rotating throwing wheel) will serve to impede at least some of the abrasive which is normally carried round by the high speed rotating wheel (several thousand r.p.m.).
It is this abrasive which accelerates round the hood which does the wear damage. The abrasive includes particles of different sizes and the finer particles are those which do most damage by scouring away the wearplates. Some of the coarser and thereby heavier abrasive particles fall back into the throwing wheel as they pass through the hood.
The upper wearplate may be-formed with at least one inwardly-directed wear dam which again intervenes into the flow path of the accelerating abrasive to decelerate same and/or cause at least some to be directed away from the wearplate. Such wear dam(s) on the upper wearplate are more likely to be omitted than provided.
Preferably the upper wearplate at each end has an inwardly-directed formation which cooperates with a complementary inwardly-directed formation at the top of each end wearplate to constitute another wear dam.
The number and configuration of the wear dams can be varied provided they function to resist the wear effect of abrasive accelerating around the hood. A secondary function of the wear dams on the end wearplates is that they divert such abrasive into the abrasive pattern of the throwing wheel.
The side wearplates, whether unitary or in two halves, are of trapezium.configuration with the usual hole for either the central infeed of abrasive to the throwing wheel or connection of the driving motor to the wheel directly or through the intermediary of a bearing housing.
The present invention also includes, separately or in any combination, an end wearplate, an upper wearplate and a side wearplate as hereinbefore defined.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which :

Fig. 1 is a side sectional view of a hood, hood lining and abrasive throwing wheel, the hood lining being in accordance with the present invention;
Fig. 2 is a transverse sectional view on the line II-II of Fig. 1;
Figs. 3, 4 and 5 are respectively a front elevation, a longitudinal sectional view and a transverse sectional view to an enlarged scale of an end wearplate, Fig. 5 also showing a modification;
Figs. 6, 7, 8 and 9 are respectively a front view, a bottom view, a sectional view on the line VIII-VIII of Fig. 6 and a sectional view on the line IX-IX of Fig. 6 of a side wearplate;
Figs. 10 and 11 are respectively a longitudinal sectional view and a half-sectional view of an upper wearplate;
Fig. 12 is a sectional view to an enlarged scale on the line XII-XII of Fig. 1, illustrating a labyrinth joint between adjacent wearplates;
Figs. 13 and 14 are sectional detail views of alternative mating configurations of an end wearplate and upper wearplate; and
.- Fig. 15 is a half-sectional view of a hood and a hood lining according to the invention.

Referring firstly to Figs. 1 to 12, the hood is generally indicated by the reference 20 and the abrasive throwing wheel by the reference 21. Both of these are of well-known construction to those skilled in the art and will not be described further.
The lining for the hood, in this instance, consists of two side wearplates 22, two end wearplates 23 and an upper wearplate 24.
The side wearplates 22 are of trapezium configuration and have a substantially centrally disposed circular hole 25, one for abrasive entry as indicated at 25A in Fig. 2 and the other for motor or bearing house connection as indicated at 25B in Fig. 2. As aforesaid, each side wearplate 22 may consist of two halves, the split line being indicated at 26 in Fig. 6. The two halves form a butt connection along this line 26.
The side wearplates 22 have recessed areas 27 for weight reduction and four screw-threaded studs 28 for use in securing them to the side walls of the hood 20.
As can be seen the edges of the side wearplates 22 are configured to cooperate with the edges of the end wearplates 23 and the upper wearplate 24 to make labyrinth joints as exemplified at 29 in Fig. 12. These joints resist.abrasive leakage in addition to relatively locating the wearplates making up a hood lining and are well known to those skilled in the art.
Each end wearplate 23 which is channel shaped is formed with two wear dams 30 on its internal face and a pair of locating lugs 23Lon its external face. The wear dams 30 are, in this embodiment, a pair of spaced inwardly and downwardly directed flanges, that nearer the bottom being smaller than the other. At its top end, each end wearplate 23 has an inwardly-directed projection 31 which cooperates with a complementary formation 32 on the end of the upper wearplate 24 to provide a wear dam (see Fig. 1).
The upper wearplate 24 has integral sides 33 so that it is channel shaped (see Fig. 2) and in addition to end formations 32 has a centrally disposed cross flange 34 connecting its sides and forming a wear dam. The upper wearplate 24 has on its external face two tapped bosses 35 for locating purposes.
The wearplates are assembled together to form a lining for the hood 20 as shown and screws or bolts 36 and 37 passing through the hood 20 engage between lugs 31 and in the bosses 35 to locate end wearplates 23 and the upper wearplate 24 of the assembly. The screw-threaded studs 28 are employed to secure the side wearplates in position.
The wearplates are, of course, dimensioned to fit into different-sized and different constructions of wheel hoods. For example wheel hoods for accommodating 12 inch, 15 inch and 19i inch diameter throwing wheels.
Such hoods, see 20 in Fig. 1, have removable lids, see 36 in Fig. 1, for removal and insertion of worn and fresh wearplates and, of course, the throwing wheel, see 21 in Fig. 1. A seal strip 38 is clamped between hood 20 and lid 37.
The wearplates must therefore be dimensioned and configured to permit such removal and insertion.
With the throwing wheel 11 in clockwise operation, accelerating abrasive carried round by the wheel firstly encounters the wear dams 30 of the lefthand end wearplate 23 which causes some of the abrasive to fall back into the abrasive pattern of the wheel and decelerates some more of the abrasive. A similar action is effected by wear dams 34 and 31, 32. The remaining accelerating abrasive impinges on the wear dams 30 of the righthand end wearplate 23 and is largely diverted thereby into the wheel abrasive pattern.
It is to be noted that, in general, the wear dams will become worn before the main body of the wearplates.
In Fig. 13 like parts as illustrated in Figs. 1 to 12 are referenced with the same numerals with the suffix "A", and in Fig. 14 with the suffix "B".
In these two instances, it can be seen that the formations 31A, 32A and 31B, '32B differ from formations 31, 32 but still provide the labyrinth and locating joint and the wear dam.
The wearplates of Fig. 13 are configured for a different hood to that used with the wearplates of Fig. 14 but, in each case, the configurations allow removal and insertion through the open top of the hood.
Referring now to Fig. 15, like parts to Figs. 1 to 12 are referenced with the numerals with the suffix "C". Here, we will describe only the differences between the two embodiments.
It will be noted that the locating lugs 31 are omitted from the end wearplate 23C, the locating bolt 36C still however engaging the wall of the end wearplate 23C.
The end wearplate 23C is, in this instance, formed with a shielding flange 39 (see also Fig. 5) which serves to impede abrasive'tending to bounce up the back of the end wearplate 23C. Such shielding flange may be provided on any of the end wearplates hereinbefore referred to.
The shielding flange 39 may be nearer the bottom of the end wearplate, in which case, it is smaller, or it may be at the bottom edge of the end wearplate.
The upper wearplate 24C may be clamped to the end wearplates 23C via bosses 40 and spring or other clips (not showm) instead of being located by bolts or screws 37.
In this instance, it can be seen that the hood 20C has straight sides, the lid 36C being dish-shaped and retained in position by bolts 41 and wing nuts 42.
Finally, it is to be noted that the present invention also encompasses the combination of wearplates as hereinbefore defined and described and the hood with or without the abrasive throwing wheel and associated operational components.

Claims

1. A lining assembly for a hood adapted to house an abrasive throwing wheel, the lining assembly consisting of two end wearplates, two side wearplates and an upper wearplate with integral sides.

2. A lining assembly as claimed in claim 1, in which each side wearplate consists of-two half wearplates butted together along a line normal to the bottom and top of the hood.

3. A lining assembly as claimed in claim 1 or 2 in which adjacent wearplates are butted together in assembly and their butting edges are configured to define locating and labyrinthal connections or joints.

4. A lining assembly as claimed in any one of claims 1 to 3 in which each end wearplate is formed with at least one inwardly-directed projection or dam adapted to intervene in the flow path of abrasive accelerating around the hood thereby substantially to reduce the rate of wear on said wearplate by the abrasive.

5. A lining assembly as claimed in claim 4 in which the projection or dam serves to direct such abrasive back into the normal abrasive pattern of the throwing wheel and eliminates abrasive rebound into the hood thus increasing blasting efficiency.

6. A lining assembly as claimed in claim 4 or 5 comprising two or more such inwardly-directed formations spaced along the length of the end wearplate.

-7. A lining assembly as claimed in any one of claims 4 to 6 in which the or each wear projection or dam extends horizontally inwards of the end wearplate, or is directed upwardly and inwardly, or downwardly and inwardly.

8. A lining assembly as claimed in any one of claims 4 to 7 in which the end wearplate has at its upper end an inwardly-directed formation, in terms of the hood wall, adapted to cooperate with a complementary inwardly-directed formation at the end of the upper wearplate to define a wear projection or dam.

9. A lining assembly as claimed in any one of claims 4 to 8 in which the end wearplate is of channel section.

10. A lining assembly as claimed in any one of claims 4 to 9 comprising a pair of spaced locating lugs on its back face adapted to receive a locating and securing bolt or screw passing through the hood.

11. A lining assembly as claimed in any one of claims 4 to 10, comprising on its back and side faces a shielding flange adapted to impede the passage of abrasive up the back and side faces when the end wearplate is located in a hood.

12. A lining assembly as claimed in any one of the preceding claims in which the upper wearplate has at least one wear dam which again intervenes into the flow path of the accelerating abrasive to decelerate same and/or cause at least some to be directed back into the throwing wheel.

13. A lining assembly as claimed in any one of claims 1 to 12 in which each side wearplate has a central hole and screwthreaded studs for securing same to the side wall of a hood.

14. An end wearplate of a lining assembly for a hood adapted to house an abrasive throwing wheel, the end wearplate being formed with at least one inwardly-directed projection adapted to intervene in the flow path of abrasive accelerating around the hood thereby substantially to reduce the rate of wear on said wearplate by the abrasive.

15. The combination of a lining assembly as claimed in any one of claims 1 to 13 and a hood for housing an abrasive throwing wheel.

16. The combination as claimed in claim 15 including the abrasive throwing wheel.

17. An end wearplate, substantially as hereinbefore described with reference to the accompanying drawings.

18. A side wearplate, substantially as hereinbefore described with reference to the accompanying drawings.

19. An upper wearplate, substantially as hereinbefore described with reference to the accompanying drawings.

20. The combination of a hood for housing an abrasive throwing wheel and a lining assembly with or without the abrasive throwing wheel substantially as hereinbefore described with reference to the accompanying drawings.