Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
9~2~Q~L
Background of the Invention
1 Field of the Invention
The present invention relates to a liner assembly
for lining interior wall surfaces of a guard housing for a
blastant throwing wheel of the type used to project par-
ticulate materials by centrifugal force from the ends of the
blades of a rotating wheel onto an object or sur~ace to be
cleaned, abraded, peened or otherwise treated.
2. Reference to Relevant Patents
_
Reference is made to the following United States
patents:
"Particle-Throwing Apparatus", U.S. Patent No.
3,160,990 issued December 15, 196~ to J.E. Bowling, Jr. et
al, hereinafter called the '990 Patent;
"Blasting Wheel Construction", U.S. Patent No.
3,191,346 issued June 29, 1965 to H.S. Chambers, hereinafter
called the '346 Patent;
"Particle-Throwing Apparatus", U.S. Patent No.
2C 3,319,383 issued May 16, 1967 to J.E. Bowling, Jr. et al,
hereinafter called the '383 Patent;
-- 1 --
~` ~
4~L
"Abrasive Resistant Articles and Alloys", U.S.
Patent No. 2,355,726 issued August 15, 1944 to Oscar E.
Harder e-t al, hereinafter called the Alloy Patent.
3. Description of the Prior Art
The '383 and '990 Patents disclose particle-
throwing apparatus of the type including a wheel which
rotates inside a guard housing for forcefully projecting a
stream of particles through an opening formed in the guard
housing for impingement wi-th objec~s or workpiece surfaces
that are to be cleaned, abraded, peened or otherwise treated.
The guard housings each have a front wall, a rear wall, a
pair of end walls, and a top wall closure. A liner assembly
is provided for lining the front, rear, end and top closure
walls. The wear liner assemblies disclosed in these patents
each include a total of twenty-three parts~ Some or all of
the parts are made from very brittle cast iron of the type
disclosed in the Alloy Patent.
While brittle cast iron liner parts are very
resistant to abrasion, they are highly suscepticle to break-
age, especially in corner regions and along edges where
extremi-ties of the liner parts have relatively thin cross-
sections. The very hard ma-terial from which these liner
parts are formed has an optimum thickness for providing the
desired -type of performance. This optimum -thickness is
relatively thin; however, the material itself is difficult
to cast in relatively thin cross-sections or in complex or
convoluted shapes. Moreover, the hardness of the material
makes machining or grinding of the liner par-ts impractical
due to cost. Accordingly, the liner parts are difficult and
expensive to fabricate, and comprise relatively fragile,
!4~
readily breakable structures which must be shipped, stored
and handled with care.
While the very hard cast metal material from which
the liner parts are formed ordinarily offers excellent
resistance to abrasive impingement, occasions arise when
particles of undesirably :Large size inadvertently are fed to
the rotating blastant wheel which is housed inside the liner
assembly. When -this happens, khe wheel vanes may be caused
to break, and broken vane pieces may be hurled against the
brittle liner parts causing liner breakage. In o-ther
situations, workpieces being treated may rebound into the
wheel enclosure and cause liner breakage. The occurence of
liner plate breakage is, in fact, quite common, and the
associated down-time for parts replacement poses a problem.
A drawback of the liner assemblies disclosed in
the '383 and '990 Patents has been the relatively large
number of liner components needed to provide a complete
liner package, and the attendant difficulties and delays
associated with removing and replacing such a large number
of parts. Moreover, the effort involved in dealing with the
large number of fastening bolts used to hold such a large
complement of plates in place undesirably prolongs down-
time.
Although the '346 Patent discloses a liner assembly
having a relatively few number o~ liner componen-ts, that
patent, and the patents referred to previously, fail to
address certain considerations. One of these considerations
relates to expense. In certain markets, it is desired to
provide a liner assembly having a smaller size and a less
~L2~L4(;1 ~
expensive technique for sealing a shaft of the wheel. A
desirable liner assembly would employ the fewest number of
liner components, while, at the same time, providing an
inexpensive shaft sealing system having an adequate abrasive
seal.
Summary of the Invention
The present invention addresses and overcomes the
foregoing and other drawbacks of prior liner assembly
proposals by providing a novel and improved liner assembly
which (1) employs a small number of parts to fully line the
guard housing of a particle-throwing apparatus, (2) sim-
plifies replacement of broken and worn liner parts and
thereby minimizes down-time associated with parts replacement,
(3) provides highly effective, abrasive-tight labyrinth
seals between adjacent liner parts and a wheel shaft, (4)
allows an intermixing of relatively thin, relatively brittle
liner parts with relatively thick, relatively ductile liner
parts, whereby the hard, brittle cast iron material from
which liner parts are customarily formed need not be uti-
lized to the exclusion of more ductile cast steel material
in providing the various parts o~ the liner assembly and (5)
provides a seal adjacent the periphery of the liner assembly
and the guard housing such that the need for a separate seal
plate is elimina-ted.
~Z~
An important feature of the invention lies in the
provision of liner parts which form overlapping or inter-
fitting joints that not only provide abrasive-tight labyrinth
seals, but also permit selected one of the liner parts to be
formed either from a relatively thin section of relatively
brittle cast iron, or a relatively thick section of rela-
tively ductile cast steel. By this arrangement, a liner
assembly can comprise principally relatively thin, brittle
cast iron liner plates, or an intermixed set of thin and
thick plates of brittle and ductile materials, respectively.
By permitting a selection of thin and thick plates
to be used together in a liner assembly, the present inven-
tion enables the user, for the first time, to independently
~ determine whether selected ones of the liner plates are to
take the form of thin, brittle structures, or thick, ductile
structures. Thus thin, brittle plates can be used in high
impingement areas where abrasion resistance must be maximized,
and thick, ductile pla-tes can be used where desired.
The joint system used to form abrasive-tight
labyrinth seals between adjacent liner plate parts is unique
in its provision of full-thickness plate edge portions which
overlap or interfi-t with edge formations of adjacent plates.
The full-thickness construction of -the overlapping or inter-
fitting plate edge portions enhances plate strength and
minimizes the likelihood of plate breakage.
4~
The reduction in the number of liner parts required
to provide a complete liner assembly minimizes the number
and lengths of joints which are present in the assembled
liner. By minimizing the number and length of joints, the
likelihood of abrasive leakage through the joints is mini-
mized, as is the problem of wear due to such leakage.
A liner assembly embodying the preferred practice
of the present invention can be substituted for such liner
assemblies as are disclosed in the '346, '383, and '990
Patents. Additionally, an embodiment of the invention is
disclosed in which the need for a separate seal plate is
eliminated, and an improved abrasive labyrinth seal is
provided for the wheel shaft, thereby enabling a less
~ expensive shaft sealing system to be provided.
15 ~
Brief Description of the Drawings
The foregoing and other features and advantages of
the invention will be better understood by referring to the
following description of the preferred embodiment and the
claims, taken in conjunction with the drawings, wherein:
FIGURE 1 is a partially exploded, perspective view
of components of a liner assembly embodying the preferred
practice of the present invention;
E'IGURE 2 is an exploded perspective view of the
components thereof displayed as if supported on a planar
surface;
FIGURES 3 and 4 are sectional views on an enlarged
scale, o-f liner assembly parts as seen essentially from
,
- 6
. ~
40~1
planes indicated by lines 3-3 and 4-4 in FIGURES 1 and 3,
respectively, with the liner assembly parts installed in a
guard housing of a particle-throwing apparatus;
FIGURE 5 is an enlargement of a portion of the
sectional view of FIGURE 3, illustrating relatively thin,
brittle, cast iron llner plates installed inside a guard
housing;
FIGURES 6 and 7 are sectional views, as seen from
. planes indicated by lines 6-6 and 7-7 in FIGURE 5;
FIGURE 8 is a sectional view similar to FIGURE 5,
but illustrating relatively thick, ductile, cast steel liner
plates installed inside a guard housing;
FIGURES 9 and 10 are sectional view, as seen from
planes indicated by lines 9-9 and 10-10 in FIGURE 8;
FIG~RE 11 is a sectional view similar to FIGURES 5
and 8, hut illustrating a combination of relatively thick
and thin cast metal liner plates installed inside a guard
housing;
FIGURES 12 and 13 are sectional views as seen from
planes indicated by lines 12-12 and 13-13 in FIGURE 11;
FIGURES 14-17 are sectional views, as seen gen-
erally from a plane indicated by a liner A-A in FIGURE 1, of
end liner plates which incorporate features of the present
invention, with FIGURES 14 and lS presenting a comparison of
rela-tively thick and thin upper end liner plates, and with
FIGURES 16 and 17 presenting a comparison of relatively
thick and thin lower end liner plates;
FIGURES 18 and 19 are sec-tional views, as seen
generally from a plane indicated by a line B-B in FIGURE 1,
~:. . I ;
~2~40~l
of top closure liner plates which incorporate features of
the present inven-tion, with FIGURE 18 depicting a relatively
thick liner plate, and wlth FIGURE 19 depicting an inter-
changeable, but relatively thin liner plate;
FIGURE 20 is a sectional view as seen from a plane
indicated by a line 20~20 in FIGURE 3;
PIGURE 21 is a sectional view, similar to FIGURE
4, of a modified form of a liner assembly installed in a
modified form of guard housing of a particle-throwing apparatus;
and
FIGURES 22 and 23 are sectional views taken along
planes indicated by lines 22-22 and 23-23 in FIGURE 21.
Referring to FIGURES 1 and 2, components of a
15~ liner assembly for lining a guard housing of a blastant
throwing wheel are indicated generally by the numeral 10.
The liner assembly 10 includes a front wall liner structure
12, a rear wall liner structure 14, end wall liner struc-
tures 16, 18, and a top wall liner structure 20.
The front wall liner structure 12 includes left,
` right and central liner plates 22, 24, 26. The rear wall
liner skructure 14 includes left, right and central liner
plates 32, 34, 36. The central plates 26, 36 are identical.
The left and right plates 22, 24 are mirror images of each
25 ~ other, as are the left and right plates 32, 34. The left
and right plates 32, 34 are shown as having ring-segment
formations 38 cast integrally therewith, but these forma-
tions can be provided as one or more separate parts, if
desired.
8 --
"
The end wall liner structure 16 includes upper and
lower liner plates 42, 44. The end wall liner structure 18
includes upper and lower liner plates 52, 54. The upper
plates 42, 52 are identical. The lower plates 44, 54 are
.identical.
The top wall liner structure 20 includes a single
top wall liner plate 62. A receiving formation 64 is pro-
vided in the -top wall liner plate 62 to receive upper edge
portions of the front, rear and end wall plates 22, 24, 26,
32, 34, 36, 42, 52 to establish a labyrinth seal there-
:~ betweenO
The plates 22, 24, 26, 32, 34, 36, 42, 44, 52, 5~,
62 form an eleven member liner assembly, but, in actuality,
comprise only eight different plate configurations which
need to be stocked as replacement parts.
A feature of the eleven-piece liner assembly 10 is
that it may be substitu-ted for the twenty-three-piece liner
assemblies disclosed in the referenced '383 and '990 patents,
and may be installed in the guard housings disclosed in the
referenced '383 and '990 patents without the necessity of
modifying these existing guard houslngs. Reference is made
to the particle-throwing apparatti disclosed in the referenced
'383 and '990 patents which exemplify and illustrate typical
environments within which liner systems embodying features
~5 of the present inven-tion may be employed. FIGUR~S 3 and 4
hereof correspond to FIGURES 1 and 2 of the referenced '383
and '990 pa-tents, and illustrate how liner components of the
present inven-tion may be subs-ti-tuted Eor liner componen-ts of
the type disclosecl in -the referenced '383 and '990 patents.
Referring briefly to FIGURES 3 and 4, a box-shaped
guard housing of essentially trapezoidal cross-section is
indicated generally by the numeral 100. The housing 100 has
a front wall 102, a rear wall 104, inclined end walls 106,
108, and a top wall closure 110. Threaded fasteners 112
secure the front wall liner structure 12 to the front wall
102. Threaded fas-teners 114 secure the rear wall liner
structure 14 to the rear wall 104. Threaded fasteners 116,
118 secure the end wall liner structures 16, 18 to the end
walls 106, 108. Threaded fas-teners 120 secure the top wall
liner structuxe 20 to the top wall closure 110. Several of
the liner plate components 10 carry cast-in-situ nuts 122
which receive threaded fasteners 112, 114, 116, 118, as is
~ described in the referenced '3g3 and '990 Patents, to hold
15 ~ these liner plate components in place on the guard housing
100. A separate seal plate 124 is disposed adjacent th~
lower periphery of the liner assembly 10 and the housing
100~ The plate 124 keeps particulate matter away from the
housing side of the liner assembly 10.
The liner plate components of the assembly 10 have
overlying or interfitting edge portions which cooperate to
define abrasive-tight, labyrinth seals between adjacent ones
of the liner plates. The design of the liner assembly
components 10 eliminates all line-of-sight openings through
which blastant could otherwise travel in penetrating liner
joints.
The left and right liner pla-tes 22, 24, 32, 34
define U-shaped grooves 140 into which opposed edge portions
of the end plates 42, 44, 52, 54 extend to defi.ne U-shaped,
wrap-around labyrinth seals. Referring to FIGURE 6, the
upper end liner plate 52 has an edge portion 150 which
extends into a groove 140 formed along one side of the front
-- 10 --
~p ~
~2~4~
wall liner plate 24. T~e groove 140 has left, right and
base surfaces 142, 144, 146. The edge portion 150 extends
closely alongside the left surface 142 and abuttingly en-
gages the base surface 146. The plates 24, 52 have in-
wardly-facing surfaces 152, 154 which extend in intersect-
ing, substantially perpendicular planes. When blastant is
propelled toward the juncture between the plates 24, 52, it
mus-t execute a plurality oE substantially right angle turns
if it is to penetrate the U-shaped, wrap-around, labyrinth
seal provided by this joint structure.
Similariy, referring to FIGURE 7, the lower end
liner plate 54 has an edge portion 160 which extends into
the groove 140 formed along one side of the front wall liner
plate 24. The edge portion 160 extends closely alongside
the right surface 144 and abuttingly engages the base sur-
face 146. When blastant is propelled toward the juncture
between the plates 24, 54, it must execute a plurality of
substantially right angle turns if it is to penetrate the U-
shaped, wrap-around, labyrinth seal provided by this joint
structure.
The various liner plates which form each of the
structures 12, 14, 16, 18 have overlapping edge portions
which define labyrinth seals between adjacent ones of these
plates. By way of example, referring to FIGURE 5, the upper
end pla-te 52 has an offset edge portion 170 which cooperates
wi-th an edge portion 172 of the lower end plate 54 to define
a right angle la~yrinth seal therebetween. The edge por-tion
170 is of L-shaped configuration and includes a downwardly
facing surface 174 and an inwardly facing surface 176. The
4~4~
lower end liner plate 54 has an inwardly-facing surface 178
which contiguously joins the inwardly-facing surface 154 of
the upper end liner plate 52, and has its upper end 180
extending in abutting engagement with the surface 174. When
blastant is propelled -toward the junc-ture be-tween the plates
52, 54 it must execute substan-tially a righ-t angle turn if
it is to penetra-te -the L-shaped labyrinth joint formed
between the plates 52, 54.
Similar L-shaped labyrinth joints are formed
between others of the plates wh\i\ h form the structures 12,
14, 16, 18. By way of example, r\eferring to FIGURE 20, the
front wall liner plates 22, 26 have overlapping edge forma-
tions 190, 192 which form a labyrinth seal therebetween. No
line-of-sight openings are provided for blastant to penetrate
through the liner assembly 10.
The liner plate components of the assembly 10, and
the joints which are formed therebetween when the components
are assembled, are configured in such a way that selected
: ones of the liner plate components can be selectively formed
from either relatively thin, bri-ttle metal material, or re-
latively thick, duc-tile metal material. By way of example,
FIGURE 5 illustrates the use oE relatively -thin upper and
lower end plates 52, 54 lining the guard housing end wall
108, while E'IGU~E 8 illustrates the use of relatively thick
upper and lower plates 52a, 54a lining the guard housing end
wall 108, and FIGURE 11 illustrates the use of a combina-tion
of thick and thin plates 52a, 5~ lining -the guard housing
encl wall 108.
Thin liner plates have traditionally been employed
in blastant wheel guard housi.ngs because the extremely hard,
~ '~
brittle alloy from which these plates have been made (the
alloy disclc~sed in -the reEerenced Alloy Patent) has an
optimum performance thickness that is relatively thin.
Making these plates thicker than the optimum thickness
significantly diminishes their abrasion-resistant perfor-
mance. Where a more ductile alloy is to be used, such as
Hadfield's manganese s-teel, this material does not cast
properly in thin cross-sections, and -thicker liner plates
are therefore required.
In accordance with one feature of the present in-
vention, the overall thickness of the upper liner plates 52,
52a, as indicated in FIGURES 14 and 15 by -the dimension "X,"
is maintained constant regardless of whether thin or thick
plates 52, 52a are to be employed. Similarly, the overall
thickness of the lower liner plates 54, 54a, as indicated in
FIGURES 16 and 17 by the dimension "Y," is maintained
constant regardless of whether thin or thick plates 54, 54a
are -to be employed. Likewise, the overall thickness of the
top liner plates 62, 62a, as indicated in FIGURES 18, l9 by
dimension "Z," is maintained constan-t regardless of whether
thin or thick plates 62, 62a are to be employed. By main-
taining constant thickness dimensions, such as the overall
dimensions X, Y ancl Z, thin and thick liner pla-te~s may be
used interchangeably to line the end and top walls 106, 108,
llO oE the guard housing lO0.
While the plates o:E liner assembly lO are pre-
ferably formed from cast metal material, as will be apparent
to -those skilled in the art, these members may also be
formed from other materials such as wrought me-tal using
welded construc-tions to Eorm -the described labyrinth seal
formation parts and the like.
~21~Q~
Referring to FIGURES 21-23, a modified form of the
liner assembly 10 and the guard housing 100 are indicated by
the reference numerals 210, 300, respectively. In com-
parison with the liner assembly 10 and the guard housing
100, the liner assembly 210 and the guard housing 300 are
less expensive to manufacture, are smaller in size, and have
a less expensive shaft sealing system.
The liner assembly 210 includes a front wall liner
structure 212, a rear wall liner structure 21~, end wall
liner structures 216, 213, and a top wall liner s-tructure
220. The front wall liner structure 212 includes left,
right and central liner plates 222, 224, 226. The rear wall
liner structure 214 includes left, righ-t and central liner
plates 232, 234, 236. The left and right plates 222, 22~ are
mirror images of each other, as are the left and right
plates 232, 234. I'he left and right plates 232, 234 are
shown as having ring-segment formations 238 cast integrally
therewith, but these formations can be provided as one or
more separate parts, if desired.
The central plate 236 includes an opening 239
through which the wheel shaEt (not shown) extends. In
contrast to the embodimen-t disclosed in FIGURES 1-20, the
opening 239 is not defined by in-terfitted plates. Addi-
tionally, hori~ontal ring protrusions 2~0, 2~1 extend la-
terally from -the Eront and back of the plate 236. The
protrusions 240, 241 essentially are annular flanges which
establish labyrinth seals in cooperation with the wheel
shaft. A Eeature of the embodiment clisclosed in FIGURES 1-
20 is that sicle l:iners 22, 2~ and 26 can be removed without
removing the wheel runnerhead, and other components of -the
wheel assembly. In FIGURES 21-23, -this feature is not
available, but a better abrasive labyrinth seal for the
wheel shaft is provided.
~ 4Q4~
The end wall liner structure 216 includes upper
and lower liner plates 242, 244; and the end wall liner
structure 218 includes upper and lower liner plates 252,
254. The upper plates 242, 252 are identical. The lower
pla-tes 244, 254 are identical. The top wall liner struc-ture
220 includes a single top wall linex plate 262. A receiving
formation 264 is provided in top wall liner plate 262 to
receive upper edge portions of the front, rear and end wall
plates 222, 224, 226, 232, 234, 236, 242, 252 to establish a
labyrinth seal therebetween. Labyrinth seals similar to the
seals illustrated in FIGURES 1-20 are employed with -the
embodiment of FIGURES 21-23. The seal construction thus
employed enables thick or thin pla-tes to be used as desired,
as described previously.
The box-shaped guard housing 300 is essentially
trapezoidal in cross-section. The housing 300 includes a
front wall 302, a rear wall 304, inclined end walls 306, 308, and
a top wall closure 310. The top wall closure 310 includes
two, parallel plates 312, 314 extending across the top
opening in the guard housing 300. The plate 312 includes
openings alignable with openings in lugs 316, 313 projecting
la-terally from the walls 302, 304, so each pair of aligned
openings can receive a fastening means, such as a nut and
bolt 320, for bolting the top wall closure 310 secure:Ly to
the guard housing 300. r~his closure construction elimina-tes
the knobs, channels and eyebolts illustrated at the -top of
FIGURES 3 and 4, is light :in weigh-t, and is relatively
inexpensive to manufacture. In a manrler similar to the
embodimen-t oE FIGURES 1-20, threaded fasteners 322 are
provided -to secure the plates, 222, 22~, 226, 232, 234, 236,
- 15 -
~Z:~4~P4~
242, 244, 252, 254, 262 to corresponding por-tions of the
housing 300.
The guard housing 300 includes a discharge opening
323 through which its blastant wheel propels particulate
material by centrlfugal force. The lower end wall liner
plates 244, 254 include laterally extending lugs 324, 326.
The lugs 324, 326 are loca-ted adjacent wall members 328, 330
to which the housing 300 is secured by outwardly extending
flanges indicatecl at 332, 334. The lugs 32~, 326 keep
propelled particulate matter away from -the intersection of
the wall members 328, 330, the flanges 332, 334, and -the
housing side of the plates 244, 254.
In the embodiment illustrated in FIGURES 21-23,
plates 222, 224, 226, 232, 234, 236, 242, 244, 252, 254 and
262 form an eleven-piece liner assembly 210, but in actu-
ality, comprise only nine different pla-te configurations
which need to be stocked as replacement parts. In FIGURES
22 and 23, central pla-tes 226, 236 are not identical in
configuration, as are central plates 226, 236 in FIGURE 2.
A feature of -the liner assembly 10 is that it may
be substituted for the twenty-three-piece liner assemblies
disclosed in referenced '383 and '390 Patents, and may be
installed in the guard housings disclosed in -the referenced
'383 and '990 Patents without the necessity of modifying
these exist:ing guard housings. The liner assembly 210, and
lts guard housing 300, are smaller then the assembly 10 and
the housing 100; the housing 300 and -the assembly 210 are
intended primarily for markets where smaller-sized, met-
rically dimensioned parts are in use.
- 16 -
a~
While reference has been made herein to a down-
wardly-opening orienta-tion of the guard housings 100, 300,
a particle-throwing apparatus of the type described herein
may be oriented to project blastant particles in any desired
direction. Accordingly, it will be understood that such
terms as "top," "bottom," "front," "rear," "upward," "downward"
and the like, as used herein, are intended simply to faci-
litate an understanding of the relative orientations of
various components, and should no-t be interpreted as being
limiting in scope.
Although the invention has been described in its
preferred form with a certain degree of particularity, it
will be understood that the present disclosure of the
preferred form has been made only by way of example and that
numerous changes in the details of construction and the
combination and arrangement of parts may be resorted to
without departing from the true spirit and scope of the in-
vention as hereinafter claimed.
- 17 -
