Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
a
CA 02366832 2001-11-29
ABRASx"VE THROWING WHE~Z.. ASSEMBLIES
This invention relates to centrifugal abrasive throwing wheel
assemblies such as are used in Shot blasting machinery.
One form of throwing wheel assembly corrlprise5, inter olio, a
throwing wheel and a set of throwing blades. The throwing wheel
comprises a pair of annular side plates conjoined in parallel
relationship by spacers. The inside face of each side plates is formed
with a number of angularly-spaced slots extending between the inner
and outer diameters of the side plate, the numbers of slots being
equal to the number of throwing blades in the set of throwing blades,
The slots in the side plates are in register and serve to mount the
thz~owing blades within the throwing wheel.
A throwing blade has at least one throwing face and its lateral
edges are usually of greater depth, viewing the throwing blade in
transverse cross-section, but not necessarily so. The opposed lateral
edges, so-called rails if of greater depth than the throwing face or
faces, of a throwing blade engage and are located in a pair of
registering slots to mount the throwing blade in the throwing wheel
and various securing arrangements, well known to those skilled in the
art, are employed releasably to retain the throwing blades within the
throwing wheel for operational purposes.
Depending on the construction and/or dimensions of the throwing
blades and the throwing wheel, andJor the throwing blade-securing
arrangement employed, the throwing blades may be inserted into their
locating slots or grooves either from the inner diameter or the outer
diameter of the throwing wheel.
Thus with all known twin side plate throwing wheel assemblies
'the side plates are internally ' slotted to accept and locate
complementarily-shaped solid lateral rails; or edges of throwing blades,
' , i.e. a female (side plate slots) and a male (solid throwing blade lateral
rails or edges) connection and location.
' The invention is especially but not exclusively concerned with
a throwing wheel asserribly in which the throwing blades are fitted
into and withdrawn from the throwing wheel through the central
opening of the throwing wheel, the blades being retained in position
CA 02366832 2001-11-29
Z
within the wheel by abutment of co-operating formations on the
throwing blades and the side plates of the thxowirig wheel. Inward
movement of the blades in the throwing wheel assembly is prevented
by the presence of the customazy removable contxol cage and vane-
type impeller with combined or separate cex~tering plate traversing the
central openings of the side plates.
An example of such a throwing wheel assembly is disclosed ire
our United Kingdom Patent No. 1 500 092,. In this patent, the Side
plates of the throwing wheel are, as is customary, radially slotted to
receive and locate the lateral rails of the throvring blades, each slot
at its inner end, i.e. adjacent to the central opening, being deeper
than the remainder of the slot to define s~ ledge against which abuts
a nose provided on each lateral rail of the throwing blade. 'thus, in
this Patent, there is disclosed lateral radial location of the throwing
blades between the side plates. In this Patent, both faces of each
throwing blade are identical so that the throwing wheel assembly is
operationally reversible,
A variation of this throwing wheel assembly is disclosed in our
European Patent No. 0198775 wherein each throwing blade has mounted
in each lateral rail adjacent its inner end, when considering the
throwing blade mounted in its thx-owing vaheel, a synthetic polymeric
or elastomeric strip which stands proud of the lateral rail and which
Lies within a dovetail--shaped groove dispcssed perpendicular to planes
containing the throwing faces of the throwing blades. These strips
serve both to provide a barrier to flaw of fine abrasive and/or
contaminations up the lateral rails of the throwing blades with
consequent wear thereon and on the walls of the slats and to
frictionally hold the throwing blades in position between the side
plates of the throwing wheel until the centering plate, with or without
the combined vane--type impellor and the control cage are located
within the central opening of the throwing wheel.
The present in~rention is not restricted to the throwing blades - ,
and the throwing wheels disclosed in our aforesaid Patents.
With our aforesaid patented throwing wheel assemblies, worn ' .
throwing blades a.re removable for .replacement purposes by firstly
removing the control cage and the vane-'type impeller with combined
or separate centering plate and then tapping the throwing blades
CA 02366832 2001-11-29
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inwardly for removal. through the central Opening in one of the side
plates.
However, in, practice it is found that due to accumulation of
abrasive between the side plates and the lateral rails of the throwing
blades within the locating slots in the side plates, release of a
throwing blade is resisted and it becomes necessary to hammer the
throwing blades inwards to effect their release and subsequent
removal. It sometirt~es happens that twe throwing blades seize solid
between the side plates nec:essitat.ing a<_rapping of the whole throwing
wheel assembly.
in addition, a consequence of s~_ir_h forcible release is the
likelihood of damage to a motor shaft, or bearing house assennbly, on
which the throwing wheel assembly is mnunted.
It is therefore an object ,of the present invention to provide a
throwing blade and a throwing wheel fc~r an abrasive throwing wheel
assembly which obviates or mitigates such abrasive accumulation
between throwing blades and side platen rsnc9 consequently the need for
such forcible xemoval from the abrasive throwing wheel assembly and
the poSSible adver5f: consequences starnmirlg t.herefran~.
Tt is also an abject of this invention to provide thro~,~ing wheel
side plates having throwing blade receiving slots of 3 Conf2gliT'3tion
whereby side plate wear, and especially side plate rim wear, is
substantially reduced.
Also known within the art of abrasive throwing wheel assemblies
are single side plate throwing wyeels w,th zadially-~ehtending throwing
blades secured, alone. one edge then eof, to the side plate by
xnterengaging and complementary male 3rd female formations on the
throwing blades and side plates respectively, the blades being
spatially grooved or slatted along said edge to accorzimodate holding
springs and releasable .locking pins releasably to lock the thraeaing
blades and the side plate together.
Examples of such throwing wheel asser~~blics are disclosed in L3S-
A-469?391, 1TS-A-324126ci and US-A-Zgf~9~~n,
CJS-A-46973~~1 disclasc~s a single side plate abrasive tfirawinP'
wheel in which the side plate has radial,ly-extending undercut or
dovetail cross--section ch.~nzae.ls, each to receive a curved,
CA 02366832 2001-11-29
~Y~
- ~ -
aperationally uni-directional throwing blade. Each blade, at one side,
has a base of complementary shape t17 a~'espectiwe channel and for
insertion into the channel. The surface .of the blade base adjacent the
floor of its respective channel has three longitudinally-spaced
.laterally-extending grooves, l.c. open to one side of the Llade base.
A leaf spring is disposed in the middle groove to urge the blade base
away from the channel floor to seat the blade base firmly in the
channel.
The outer end of each channel includes as part of its floor an
angular well. with a magnet incor porated in its floor.
The outer end of each throwing blade has a laterally open r amp
configuration disposed opposite the well in the channel floor when the
throwing blade is mounted in its respective channel.
Each blade is inserted in its reshe.ctive channel, inwax'd radial
movement of the blade being restricted by a runnerhead disposed
centz~ally of the side plate.
A secuxring pin is inSFrted angularly irito the well/ramp chamber
between the blade base. and channel floor frurz~ the periphery of the
side plate and is then aligned with the throwing blade axis in which
position it. is magnetically secured. The thx~owing blade is then rtioved
radi,ally outwardly from the r unn~rhead to clamp the securing pin
between the blade bast a.n<i channel floc>r thereby removahly fi~i,ng the
throwing blade in position an the runn~:r head, the leaf spring, as
mentioned, firmly seating the blade base in the side plate channel,
Elade reriioval is effected by a reversal ref the above actions.
US-A-34,1266 discloses _-~ szng2e side. plate abrasive throwing
wheel which ha.s opertitionally bi-dir~:otional throwing blades, each
having at one side a dcwetailwshaped base adapted for engagement in
a complen uentary-shaped channel in the side plate and having cut-outs
or grooves adapted to receive a holding leaf spring and a locking pin
which is wedge shaped and which is adapted to be clamped between
a tapered cut-out in E:he lalade base arid a complementary tapered part
of the channel.
US-A-28692$9 discloses a Single side plate throwing wheel with
the side plate mamntitig radially~-extending blades each having at one
side a davetaxi-Shaped base engageable in a complementary dovetail-
shaped channel in the side plate. Each blade base has three
CA 02366832 2001-11-29
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longitudinally-spaced ' slots or grooves with the middle one
accommodating a leaf spring which cooperates with the floor of the
respective channel to seat the blade base firmly in the latter. The
outer slot or groove is open to the periphery of the side plate whiclu
remaUrably mounts a locking pin against which an inner wall of the
outer slot or groove is urged by a centrally but removably mounted
cage and impellor arrangement of the abra$ive throwing wheel to
secure the throwing blade against radial movennent.
It will be note that all three of these abrasive throwing wheel
constructions have one side plate with dovetail or undercut channels
adapted to receive the dovetail bases of throwing blades with the
bases having longitudinally spaced slots or grooves far receiving leaf
spritzgs to hold the bases against the walls of the channels and
removable looting .pins for resisting radzal outward mUvernent al ttze
throwing blades.
The throwing blade securing arrangements arc- thus relatively
complex, not always easy to fasten and/or release, and there rs always
the risk of mi.$placement or loss of the loose locking pins and holding
springs.
It is a further object of this invention to provide, compared
with this construction of abxasivE thr owing wheel assembly, one which
is substantially simpler to assemble and disassemble and which does
not have the disadvantage of loose parts liable t.o misplacement or
loss.
According to a first and broadest aspect of the present
iwcrentian there is provided a throwing blade for mounting in a
throwing wheel of an abrasive throwing wheel asserrtbly wherein a
lateral rail. or edge of the throwiy blade is gr<.>oved for blade
loc.:ation pLlx'pOSeS, the: throwing 'glade hf=ing characterised in that it
is adapted for seCUrement in a two side plate thrnwing wheel, and in
that both lateral rails or edges of the throwing llacie arc' gr;~ove~r
inwardly frorj~ t1e tip of the blade for blade loc:atic~;; purposes.
As a result of the reduced area of contact resulting from t:h
grooves hitherto jamming abrasive is either not retaine.cl between the
throwing blade lateral, rails nr edges and the side F~lates of the
throwing wheel, or, if it is, its removal is relatively easily effected
before, and during, throwing blade removal.
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,t.b _
Preferably, each lateral rail or edge of the throwing blade is
formed with a groove configuration extending inwardly from its tip.
The groove configuration may, depending on the throwing blade
securing arrangement emplayed, extend 'the full length of the throwing
blade lateral rail or edge, or may extE~nd inwardly from the tip for
part of the .throwing. blade .length.
Preferably, in the latter r_ase, the graove configuration stops at
ox adjacent a thrawing blade secuzing :~OrITl3tlon.
Preferably, the. securing formation is within each lateral rai i or
edge of a throwing blade.
preferably, in the case of our aforesaid patented t lornwirng
blades, the groove configuration terminates at the locating nose of the
lateral rail.
~'refer'abl~r, the groove configuration is of V-r_woss-section. Fr
may, however, be of other cross-section, such, for example, as I_,' or
rectangular cross-sectiarl.
According to a third aspect of the present invention there is
provided a side plate for a throwing wheel of an abrasive throwing
wheel assembly, the side plate hairy o:f annular construct:ton with a
plurality of angularly-spaced radial slota extending between the inner
and outer diameters of the side plate, each slot being divided or
paz'titioned for at least part of its radial length by a throwin,~ bla.dE
locating projection to define for said radial length part. of a pair of
side-~'~y-side sub-slots.
According to a fourth aspect. of the present irWenti.ori tZoez'e is
provided a throwing wheel far an ahra:rive throwing wheel asscrnbly>
the throwing wheel comprising a pair of side. plates as r_lefined in the
immediately prec.e<ling paragraph connected in parallel .relationship by
angularly-spaced spacers.
It is to be cF,eaz'ly understood, however, that the throwing blades
CA 02366832 2001-11-29
in accordance with the present invention can and may be employed
with conventional and known throwing wheels, i.e. those where the
side. plates have single simple slots for receiving and locating
throwing blade lateral rails or edges.
According to a fifth aspect of the: present invention there is
provided an abrasive throwing wheel assembly comprising a throwing
wheel constituted by a pair of parallel side plates of annular
construction joined by' angularly-spaced spacers with the facing
surfaces of the side plates being formed with a plurality of
registering angularly-spaced radial slots e~tetr~ding between the inner
and outer diameters of the side plates, and each slat being divided
into two parallel sub-slots for at least part of its radial length by a
blade locating projection, and a plurality of throwing blades mounted
between the side plates with the lateral rails or edges of a respective
throwing blade being located in a pair o:f respective registered slots,
the lateral rails ar edges of the throwing blade being grooved
inwardly from the tip of the throwing blade to~ receive the locating
projections in the slots.
The blade grooves and the side wall blade locating projections
may be of such a c4nfiguration that there is angularly spaced facial
and/or line (paint) contact between the lateral rails or edges of the
throwing blade and 'the blade locating projections of the side plates
thereby easing throwing blade removal from between the side plates.
The aforesaid fifth aspect Qf the present invention may be
modified in that the blade locating projections axe omitted, i.e. the
radial slots are simple single slots.
Zn this modification there are angularly spaced areas of facial
contact between a side plate and the adjacent lateral rail or edge of
a throwing blade.
A sixth aspect of the present invention is concerned with a
thrr~wing blade of the present invention as hereinbefare defined
incorporating the synthetic polymeric or elastomeric lncatian and
barrier strips. In this aspect, each atrip is moulded, preferably
' injection moulded, into its dovetail-shaped groove in the throwing
blade lateral rail or edgE and .is in the form of a wiper blade which
will give the required frictional holding and abrasive barrier
characteristics.
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The groove may be other than dovetail-shaped provided it ca::
retain the flexible wiper blade in position on the throwing blac:e. '
is likely that the flexible wiper blade will only stand proud lateral 1 v
of the throwing blade lateral rail or edge.
In an alternative construction a synthetic polymeric or
elastomeric insert rnay be located in the bottom of one, or each,
groovre of a throwing blade, preferably spaced from the blade securing
formation for blade retention purposes.
Embodiments of the present invention will now be described,
by way of example, with reference to the accompanying drawings, in
which:-
Fig. 1 is a perspective viewof one form of throwing blade
according to present invention;
the
Figs. 2 to 4 are respectively a side view, a plan view
and a
sectional view Line IV-IV Fig.2 of the throwing blade of
on of Eig. . ,
Fig. 5 is a plan view the inside face of a side plate
of for a
throwing wheel according the present invention showing
to twu
alternative of dual slotsor
forms grooves;
Fig. 6 is a on
sectional view the
line
VI-VI
of
Fig.
5
through
the
slots or grooves;
Figs. 7 to 9 are fragmentary sectional views, to an enlarged
scale, of respectively two alternative forms of throwing hlades and
side plates in accordance with the present invention, and a throwing
blade in accordance with the present invention used with a
conventional side plate:
Fig. 1d is a fragmentary perspective view of the inner end of the
thxowing blade of Fig. 1 and an ,adjacent throwing wheel side plate
in accordance with Figs. 5 and 6:
Fig. 11 is a perspective view of another and pref erred I crm ;:v
throwing blade according to this invention;
Figs. 11A and 11B are respectively fragmentary su~a anu er:;
views of the blade of Fig. 1I;
Fig. 12 is a detail fragmentary sectional view show~mg a
preferred throwing blade and wheel side plate connection according ca
this invention;
Fig. 13 is a side view of a throwing wheel side plate ar.d
throwing blades illustrating various features of the present invention:
CA 02366832 2001-11-29
7
Fig. 14 is an end view of a throwing wheel according to this
invention.
Fig. 15 is a fragmentary sectional elevation through an abrasive
throwing wheel assembly incorporating the present invention; and
Fig. 16 is a fragmentary sectional view, to an enlarged scale,
of yet another form of throwing blade and side plate.
Briefly, the throwing blade 20 (see Figs. 1 to 4 and Fig. 10)
has an inner body 21 with integral lateral rails 22, the inner body
21 having two identical throwing faces 23 which renders the throwing
blade 20 suitable for use in a reversible (bi-directional) abrasive
throwing wheel assembly.
At the inner end of each lateral rail 22 is a laterally-
projecting protuberance 24 tapered to define a blunt nose 25.
The laterally-projecting protuberance 24 has formed therein a
dovetail-shaped slot 26 in which is force fitted a polymeric or
elastomeric sealing strip 27 which stands proud of the protuberance
24 both laterally and at its ends.
The sealing strips 27 assists in reducing abrasive wear on the
side plates of a throwing wheel in which the throwing blade 20 is
mounted and in the location and retention of the throwing blade 20
between the side plates during throwing wheel assembly.
In connection with these sealing strip 27 reference is made to
our European (UK) Patent No. 0148775.
In accordance with the present invention each lateral rail 22 is
formed with a V-groove 28 open to the side face of the throwing blade
20 and extending from the tip of the latter to the blunt nose 25 of
protuberance 24.
These grooves 28 define female configurations which are used to
locate and retain the throwing blade 20 in position between side
plates of a throwing wheel.
Due to this grooving of the lateral rails 22 the transverse
width W of each lateral rail 22 is greater than usual.For example, 10
CA 02366832 2001-11-29
8
millimetres as opposed to the usual 7 millimetres.
Zt is to be understood that the slots 26 and strigs 27 may be
omitted if desired.
Referring now to the throwing wheel (see Figs. S to 3 atxd Fig.
14) within which the aforesaid throwing blades ZO can be rempvably
mounted, this comprises a pair of annular parallel side plates 29
joined together by spacers 29A, there being, between angularly~adjacent
spacers 29A, throwing blade locating slots.
Each side plate 29 (see Figs. 5 a.nd 6 especially) is, as aforesaid.
o~ annular construction and is formed with a series of ang~uarlv
spaced, radial, throwing blade locating slots generally indicated at .su.
More specifically in accordance with the present invention eac:r
of these slots 30 is divided into two sub-slots 30A, 30B for part of the
radial length of the slot 30 by a centrally disposed projection a0C
extending from the outer circumference of the side plate 29 to a
recess 3I at the inner end of the slot 29, which recess 31 defines a
ledge 3Z against which the nose 25 of a throwing blade rail 22 will
abut.
The sub-slats 34A and 30B are of rectangular cross-section (see
Fig. 't) as is the separating projection 30r.
In Fig. 8 the sub-slots 30A and 30B are wider than those of the
side plate of Fig. 7 and the lateral face:. 30D of each slot 30 remote
from the projection 30C is inclined away from the latter arid inwardly
relative to the outer face of the side plate 2y_
Also, in this construction of side plate the corner;; o: t he
projection 30C are chamferEd to provide bearing surf aces .3Uf~:.
In Fig. 9, the slot or groove 3U in the side plate 2~a rs a
conventional simple slot as is currently usual in the side plates of
throwing wheels. The configuration of the lateral rail 22 of the
throwing blade 20 is shown to conform with that of ~'xg. 7 but it may
equally conform to that of Fig. 8.
'this blade 20 (Fig. 9) may be secured between the sidF plates by
the conventional back fixing method well known to those well skilled
in the art and in this instance the grooves 28 will, or may, axtend the
full length of the blade 20.
1t is to be understood that all the slots or grooves 30 in the
side plates 29 of a particular throwing wheel will be of the sarnc~
CA 02366832 2001-11-29
9
configuration, i.e. iri accordance with Fig, 7 or Fig. 8 or Eug. ~ tc.~r
example.
Referring again to Figs. S to 7 and Figs. ~> 6 and 8 it will be
noted that in the latter case the overall width of the slats .s0 are
wider as a result of the inclined faces 30D and it is considered that
these inclined feces 30D will assist in dispersal of abrasive from the
slots 30 circurnferentially as well as radially during throwing wheel
assembly operation.
In both Figs. 7 and 8 it will be noted that location of a
throwing blade 20 between side plates 29 is effected by th.e engagement
of the projections 30C (male formations) on the side plates 29 within
the slots 30 (female formations) on the throwing blade Z0.
In the Fig. 7 configuration it will be seen that them. :s only
point or line contact between the throwing blade 20 and pr~jeet.ic~n~
30C of the side plates 29 of the throwing wheel, whic.tu pc~or~L or line
Contact is spaced axially from circumfere:ntially spaced areas o~ :ac:idl
Contact between the side face of the throwing blade L~ acmi tine
bottoms or the .grooves 30.
While there is ii~nited face-to-face contact between the throwing
blade 20 and the projections 30C pf the aide plate 29 of the throwing
wheel in the Fig. 8 configuration, it will be noted that there is bath
circumferentiai and axial spacing between the throwing blade 20 and
its adjacent side plate 29.
In the Fig. 9 configuration, while the rail 22 of the throwing
blade 20 makes face contact with the side plate 29 on all three sides
there is a major interruption in this contact as a result of the
grooves 28 in the blade rails 22.
Due to the axial or axial and circumferential spacing between
the throwing blade lateral rails and the side plete.~, al? ~~tt.e~~<:
configurations assist in removal of worn throwiry i.~idc:a:~~ ~;a l r~com
between the side plates 29 of a throwing wheel.
. ' A comparison of the throwing blades of Figs. 7 ac~ci n :~t~«w;; c:,;~t
the side plate adjacent face. of the lateral rail c1 0t:~e Tarter
~ - presents a lesser area of rail contact to the side plate 29 than the
former. This is due to the different contact canfigurat:on~ between
the throwing blade rails 2~ and the projections 30C of the grooves 30
of the side plates 29.
CA 02366832 2002-09-13
Reference is now made to FIGS. 11 to 14 which show a preferred
throwing blade construction and throwing blade and side plate
connection according to this invention.
The throwing blade 40 has a body 41 defining identical throwing
faces 42 bounded by two lateral rails 43 of greater depth than the
body 41.
Each lateral rail 43 is formed with a V-groove 44 extending
from the tip 41A of the blade 40 for a major part of its length to
a location 45 where the rail 43 is left full, up to the tip 41B of
tie blade 40 for a minor part of its length.
The groove 44, therefore, is arrested at 45 to define a
securing formation.
A synthetic polymeric or elastomeric insert 46 is secured in
any convenient manner within each groove 44 towards the bottom
thereof, i.e. it. does not fill the groove 44, and is spaced as
indicated at 47 from the blade securing formation 45.
These inserts 46 serve primarily to assist in blade retention
between the side plates of a throwing wheel during assembly and act
secondarily as abrasive flow barriers during use of the throwing
wheel.
The inserts 46 may be omitted or alternatively may be provided
on one side only of the throwing blade 40.
Throwing blades 40 in accordance with FIG. 11 may be produced
by forming, in any convenient manner, a length of blade strip with
the grooves 44 extending the full length of the strip, cutting the
strip into the desired throwing blade lengths and thereafter, at
one end, welding, tapping or otherwise securing within the grooves
44 inserts to provide the blade securing formation 45, or even
simply depositing weld material. in the grooves 44 at said ends to
provide the necessary abutment surfaces. The abutment surfaces 45
can be provided in the grooves 44 in any convenient fashion.
It is to be understood that an abutment surface 45 can be
provided in only one groove 44 of a throwing blade 40 if desired.
It is also to be understood that the abutment surface or
surfaces can be omitted. if the throwing blades are to be back fixed
or side fixed in conventional manner as is well known to those
skilled in the art.
Reference is now made particularly to FTG. 12 in which 50
CA 02366832 2001-11-29
11
indicates a throwing wheel side plate with a preferred form of slots
fl {only one shown).
The slot S1 viewed from the circumference oz the side plate 50
has a flat base 52 bounded by two diverging inclined side wahs 53.
A locating projection 54 is provided centrally of the slot 51 and
is of triangular configuration with a narrow flat top in cross-section.
'x"he following dimensions are given solely as examples and are
in no way to be considered restrictive.
The angle a defined by the side walls of the projection 54 is
equal to 90° while the angle b subtended by the sides walls of the
groove 44 is equal to 100°.
Consequently the blade rail 43 makes only line ar point contact
with the projection 54 at two angularly spaced locations, the remaining
adjacent surfaces of the blade rail 43 and the projectir~n 54 bei~ig in
spatial relationship.
The angular width of the slat 51 at its widest part A is three
times the thickness $ of the throwing blade rail 43 and at its
narrowest part C is two and one half times thickness B.
There is thus a substantial clearance between the lateral walls
53 of the slot 51 and the respective front or back face 43A, 439 of the
lateral rail 43 of the throwing blade 4n and even greater spacing
between each inclined face of the projection 54 and the adjacent
inclined face 53 of the slot 51, the central projection 54 and the
inclined side walls 53 defining, as has previously been mentioned
parallel sub-slats 51A.
It can thus be seen from the above that the pc~ssibilit.y of tre
abrasive cacchment or trapping between the tiZrowar~~ blades a.~:ii the
side plates is substantially reduced when compared with existing
throwing wheels of this general character, i.e, two side plates witri
replaceable throwing blades, so that blade removal is facilitated to d
considerable extent.
Another important ' advantage of the throwing blade and side
plate slot configuration of Fig. 1.2 is reduction in wear on the side
~ - plate 54, especially at its outer circumference or rim, thus increasing
the working life of the throwing wheel.
It is well known to those skilled in the art that with known
conventional throwing wheels the abrasive or short, during operation,
CA 02366832 2001-11-29
12
accelerates up narrow radial gaps oetw.a_en the walls of the radial
slots and the side rails or edges of the throwing blade located it
these slots and; on reaching the rim o:E the side plates, the high
velocity abrasive or short sweeps along the rims of the side plates
and subjects same to Considerable and sometimes very rapid wear. The
side plates often become knife-edged at their rirr2s and the throwing
wheel requires to be replaced. The reason far this rim wearing action
of the high velocity abrasive or shot is not fully understood but is
a~ well established fact.
Viewing Fig. 12, it will be manifest that, due to the radial slot
configuration (wide with inclined side walls) no abrasive or shot
constraining narrow gaps are present between the inclined walls of the
slot and the side rails or edges of the blade. This situation would
equally apply if the walls 53 were vertical and spaced ~uffic:ientiy
away from the lateral rail 43 of a blade 40.
Consequently there is no build up of radially direc:cN~? anti
confined abrasive or shot velocity, the abrasive or shot dispersing
both angularly and radially in a free, non-confined manner due tca
centrifugal force during throwing wheel assembly rotation with
resulting substantially lESS side plate wear and therefore increased
working life of the throwing wheel.
Reference is now made particularly to Figs. 13 arid 14 which show
a throwing wheel b0 (see Fig. 14) constituted by two parallel side
plates 50, SOA joined, in conventional manner, by spacers 61.
The side plates 50, 50A are formed with registering slats 51 as
described with reference to Fig. 12 in which a fitted throwing blade
40 as described with reference to Fig: 11.
Firstly, it is to be noted that tYie central prc~ject.icm 54 rr,~i-. k~e
of continuous length as exemplified at location X ur it ;jWy' t:e
interrupted or dI,SCCWtlnuOus as indicated at 1c.>ca~ imu Y,
A throwing blade 40A o: a length sufficient to pass tr~rc~~i~tu t:~~_~
central hole 55 of one of the side plates 5U can, as indicateu ~v
arrows, be slid into the slots 71 until the: securing locations ~~ abut
the inner ends of the projections 54 which are receiued in the grooves
44.
If it is desired to eEnploy throwing blades 40B or a lengt
greater than the diameter of the central hole 55 this can be done by
CA 02366832 2001-11-29
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a
sliding the blade 4013 down a sub-slat 51A then aligning the grooves
44 with the eeratxal projections 5~3 and then pulling the blade 40B back
out until the securing formations 45 abut the ends of the central
projections 54, The width of the sub-slots 51A permits such a
manoeuvre.
As a result of the present invention and by suitably
dimensioning the blade locating projections it is possible for a gzven
size (external diameter} of throwing wheel to eutploy throwing blades
of different lengths, the throwing blades, as aforesaid, being
insertable between the side plates either through the centre of the
side plates or from the outside rirrz of the side plates depending on
throwing blade length, the sub-slots being used far such outside
insertion.
The throwing blades of a given throwing wheel will usually be
the same length.
Referring to Fig l~ it can seen that the throwing blades 20 (40}
as hereiz~before described in Lhe throwing wheel assembly are retained
in position between the side plates 29 (50) as hereinbefore described
after central or external insertion by the control cage 33 and the
integral centering plate 34 and vane-type irnpellor 35 wxticl is
removably secured to a wheel hub 36 bolted to one of the side plates
29 and secured to a motor shaft 37.
It is to be understood that the grooves ~8 {49) in the lateral
mils or edges 22 (43) of a throwing blade 20 (40) may extend the full
length thereof and in this instance the slots 3Q (51} in the side plates
29 (50) may also extend the full radial distance between inner and
outer diameters of the side plate 29 (50).
With such a configuration of throwing blade and side plate, the
throwing blade may, far example, be back-fixed through a spacer of
the throwing wheel, or side--fixed through a side plate as is well-
known to those skilled in the art.
Fig. 16 shows a possible further construction of throwing wheel
in which the side plates 29 are not formed internally with tlvrowuiy
' blade locating slots 30 but only with inwardly lutojectiry, ribs 38
equivalent to projections 300.(54), ttoe thrc>wmg hlacie_> ~U (40j t»~uiy;
grooved in their lateral rails or eci~;es 22 (43) as df~~>c-.rik>ed, eim:,~
providing the reduced inter-facial contac:t., male/lernale cc~ot~eccmn
CA 02366832 2001-11-29
14
between side plate/throwing blade which is the characteristic feature
of the present invention.
The ribs 38 may be integral mith or separate and attached to the
side plates.
According to a se~renth aspect of the present invention,
therefore, there is provided an abrasive throwing wheel assembly
comprising a throwing wheel ha ing annular side places with
registering inwardly-directed projections provided thereon for
mour~ting throwing blades formed with a lateral rail or edge of
gxooved or recessed configtaration within which a projert:ion can be
located.
This aspect of the present invention also extEnds to a side plate
for a throwing wheel having integral or separate but att.a~t~ed
projecting ribs only (no slots or grooves) on its throwing blade
mounting face,
