Ceramic brick

A weldable abrasion resistant ceramic brick is formed with spaced recesses extending angularly into the brick to undercut a surface thereof and interlock with a weldable insert having angularly extending projections mating with and insertable into the recesses. Each recess may be defined by a wall inclined into the undercut for camming an aligned projection into the undercut. The insert and brick may be interlocked and thereafter welded to a substrate, or the insert may first be welded to the substrate and thereafter interlocked with the brick. The invention is particularly useful with comparatively thin abrasion resistant wear plates that heretofore could not be welded satisfactorily to a substrate.

BACKGROUND OF THE INVENTION 
It is conventional in industries involving the transportation or storage of 
abrasive materials, such as coal, various mineral ores, or other 
abrasives, to provide a steel substrate or liner for a wall or surface to 
be protected, and thereafter to weld specially prepared abrasion resistant 
ceramic tile or bricks to the backing. The surface to be protected may 
comprise by way of example the wall of a pipe or a chute exposed to 
abrasion, or surface portions of a military vehicle exposed to shrapnel or 
small arms fire. 
Such bricks are commonly one inch thick fired silicon ceramic, such as an 
aluminum-silicon oxide or a silicon carbide compacted under high pressure 
from a dry powder and optionally with a suitable binder. The typical brick 
has four by six inch faces, although the dimensions may vary appreciably, 
say from one-half to two inches in thickness, with faces ranging from less 
than four inches in the shorter dimension to more than nine inches in the 
longer dimension. Also the brick may be molded from a molten abrasive 
resistant material such as basalt or an aluminumzirconium-silicate. 
A common weldable brick is formed with a central welding hole about one 
inch in diameter that extends through an outer face of the brick and is 
constricted slightly adjacent to the opposite inner face to confine a 
weldable metallic insert. The latter is inserted into the larger or 
unrestricted opening of the welding hole and is retained adjacent to the 
restricted end by friction. With the welding insert arranged coaxially in 
the hole, the metal insert is welded to the steel backing or liner, either 
by conventional MIG (metal inert gas) welding or by conventional use of an 
arc welding rod. Thereafter the unrestricted opening of the welding hole 
is closed by insertion of a cylindrical closure plug. 
In some instances, it is preferable to weld the metal insert by 
conventional arc welding to the steel backing or liner, but arc welding is 
not particularly convenient with the type of brick available heretofore 
because it is difficult to maintain the metal welding insert in a coaxial 
position at the reduced end of the hole. The welding insert is provided 
with a central opening through which a welding rod or wire must pass in 
order to contact the steel wall or backing. When the welding rod is 
extended through the aforesaid central opening in the welding insert, the 
latter is frequently knocked out of alignment by the rod and welded in a 
cocked position to the steel liner. A similar problem arises even during 
MIG welding when the MIG welding wire is inserted through the welding 
insert into contact with the steel backing or liner to which the brick is 
to be secured. 
Not only will the resulting weld be less secure, but the cocked insert in 
some instances prevents the cylindrical closure plug from fitting flush 
with the outer surface of the brick. The plug will thus be subjected to 
excessive abrasion and will rapidly wear away. Furthermore, although the 
cylindrical plug is usually cemented within the welding hole, it 
frequently works loose even when it is flush with the outer surface of the 
brick, whereupon the metallic insert will rapidly wear away by the 
abrasive action and the entire brick will be dislodged. 
Even if the metallic insert is properly located and welded to the steel 
backing, the cylindrical closure plug cannot extend axially within the 
welding hole to the extent desired because a certain amount of space must 
be allowed to accommodate the situation when the metallic insert is cocked 
out of its coaxial alignment within the hole. Accordingly, the wear 
resistant thickness of the brick at the region of the approximately 
one-inch diameter welding hole will be considerably less than the 
thickness of the adjacent portions of the brick. When the thinner 
cylindrical plug eventually abrades away, the metallic welding insert is 
rapidly disintegrated by abrasion at the exposed hole. 
In addition, the one inch centrally located hole tends to weaken the brick 
across the diameter of the hole. In consequence, the comparatively brittle 
ceramic brick tends to break when subjected to impact during use, or when 
the installer of the brick attempts to break off a portion in order to 
provide a close fit near the edge of the wall to be lined. In that event, 
the brick tends to crack at the middle through the one inch hole instead 
of at the region where the craftsman's hammer strikes the brick. 
An additional objection to bricks of the type described is that three loose 
pieces are required, i.e., the brick, the insert, and the cylindrical 
plug. The insert may be cemented in place, but the cementing involves an 
additional operation and increases the cost of the brick. 
The above noted objections in regard to conventional ceramic or abrasion 
resistant bricks are magnified for bricks of less than an inch thick. 
Although many situations exist where weldable ceramic bricks, of say less 
than one-half inch thickness would be desirable, especially where the 
excessive weight of thicker bricks is a major problem, no such brick 
suitable for use in a wide range of applications has been available 
heretofore. Also solid bricks with no through hole are desirable for use 
in many applications, regardless of thickness. Such bricks are stronger, 
less subject to fracture by impact, and exhibit maximum wear life when 
subject to abrasion. However, attempts to secure solid bricks as an impact 
and abrasion resistant protection to a substrate have not been successful 
because of the imperviousness of the brick to the adhesive, usually an 
epoxy resin, the brittleness of the adhesive as it ages, and the extensive 
preparation of the substrate surface required for the cementing. 
SUMMARY OF THE INVENTION 
Important concepts of the present invention have been to provide 
improvements in a ceramic or abrasion resistant brick of the general type 
described above, and also to provide improvements in a brick referred to 
herein as a "solid" brick because it does not require a large opening or 
through-hole to contain the body of a weldable insert or to enable welding 
of the insert to a substrate, and also to provide a unique method for 
fabricating the brick and for securing it to a substrate. Being "solid", 
the brick is especially suitable for use where comparatively thin bricks 
are desired, although the present invention is also suitable for use with 
comparatively thick bricks where ultra high impact resistance and wear 
resistance are required. 
The brick is formed with a plurality of comparatively shallow spaced 
recesses, preferably two, spaced by a plane surface of the brick and 
opening into and undercutting that surface to cooperate with a weldable 
sheet steel insert having a plane base adapted to lie flush with the brick 
surface spacing the recesses and also having a corresponding plurality of 
flanges or projections arranged to be extended into the recesses upon 
suitable deformation of the insert so as to underlie and interlock with a 
portion of the brick surface. In one modification of the insert, its 
projections are arranged to confront and extend toward the openings of the 
recesses for insertion thereinto. One wall of each recess inclines from 
the recess opening into the undercut and is arranged to engage the distal 
end of the confronting projection and deform and cam the latter into the 
undercut when the insert and brick are forced toward each other. Thus the 
several projections, when deformed into the undercuts of the spaced 
recesses, interlock the insert and brick. When the insert and brick are 
forced together to deform and interlock the projections within the 
recesses, the sheet steel body of the insert between its projections may 
lie snugly against the adjacent exterior surface of the brick that spaces 
the recesses. 
The result is a weldable brick with no through-hole, that utilizes minimum 
ceramic thickness to effect an interlock with a weldable insert, and is 
particularly suitable for use with thin ceramic bricks or wear plates in 
the range of approximately a quarter of an inch thick. Such bricks or wear 
plates have extensive applications in industry, but because suitable 
weldable thin wear plates have not been available heretofore, wear plates 
thicker than necessary have been used in order to avoid the unreliability 
associated with adhesive mounted plates or bricks and to obtain a weldable 
feature, with consequent overdesign, excessive cost, and weight penalties. 
The above described brick may also be secured to a substrate in a unique 
manner. Prior to interlocking the brick and insert, the latter may be 
secured first to the substrate at the location where the brick is desired, 
preferably by welding if the substrate is weldable, or by other means such 
as a bolt or rivet, with the projections of the insert extending outwardly 
from the substrate. Thereafter the brick, with its recesses aligned with 
the distal ends of the projections, is forced toward the insert to cam and 
deform the projections into the undercut recesses. Of course thicker 
bricks may be cored sufficiently between the undercutting recesses to 
enable the entire body of the insert to be recessed into the confronting 
surface of the brick, and likewise, thicker bricks secured to an insert as 
described herein may be provided with through-holes to enable their welded 
attachment to a substrate as disclosed in my copending application, 
including welding from the back side of the substrate through a pre-formed 
hole therein. The latter procedure enables use of a weldable brick having 
no throughhole provided that the back side of the substrate is accessible. 
It has been conventional to form a green ceramic brick by compacting dry 
powdered ceramic within an open top female die cavity by means of a mating 
male die plunger dimensioned to move into the open top and seal the same 
against extrusion of ceramic powder therefrom during the high pressure 
compression operation, but to allow the escape of air from between the 
juxtaposed male and female die parts. Thereafter the green brick is baked 
or fired to complete the extremely hard abrasion resistant brick. The 
female die cavity provided side and bottom walls to form the edges and one 
face of the brick, and the male die plunger formed the opposite face of 
the brick. Inasmuch as the particles of the ceramic powder prior to being 
compacted together contained large quantities of air therebetween, the 
conventional molding procedure involved a preliminary or partial 
compression to compact the ceramic particles closely together to expel the 
air therefrom, followed by a momentary dwell period to allow time for the 
air to escape. Thereafter the compression is resumed to effect the final 
extremely high tonnage pressure, followed by a second momentary dwell 
period to allow time for the escape of residual air, and thereafter 
ejection of the green brick from the mold. The resulting brick is usually 
a rectangular block or plate, and any surface indentations are necessarily 
shallow with outwardly sloping edges. The formation of undercutting 
recesses of the type described herein was impossible by known procedures 
because the extremely high molding pressures required to form a high 
density abrasion resistant ceramic brick would distort or cave in such 
recesses as soon as formed. 
Another important concept of the present invention results from the 
discovery that if recess forming punches are forced into the surface of 
the brick after the aforesaid first dwell period and before the final high 
tonnage compression, and are withdrawn after completion of the high 
tonnage compression and the second dwell period, the resulting 
undercutting recesses will not h=deformed when the recess forming punches 
are withdrawn from the newly formed green brick. 
A modification of the conventional brick molding apparatus comprises a pair 
of hydraulically actuated punches carried by the male die plunger and 
shaped to form the above described recesses The punches are connected to a 
corresponding pair of double acting hydraulically actuated pistons within 
cylinders contained in the body of the die plunger and, upon completion of 
the first dwell period, are forced angularly into one surface of the 
partially compacted ceramic to the extent necessary to form the 
undercutting recesses, as for example at approximately a 60 angle of 
inclination to the brick surface and at least an eighth of an inch beyond 
that surface. Thereafter the final compacting pressure is applied to 
compact the powdered ceramic tightly against the male die plunger and 
around the inclined punches. After the second dwell period, the punches 
are retracted and the molding pressure is immediately released. 
By virtue of the multiple stage compacting sequence described, the undercut 
recess may be formed and the recess forming punches may then be withdrawn 
without deforming the recesses or allowing them to collapse under the 
final compacting pressure. Movement of the die parts to the preliminary or 
partial compacting position, followed by the first dwell period to allow 
the escape of air, sets the powdered ceramic sufficiently so that after 
insertion of the recess forming punches, the subsequent high tonnage 
compression does not cause unbalanced compression forces on the powdered 
ceramic around the punches sufficient to cause deformation of the recesses 
when the punches are withdrawn or when the formed green brick is 
subsequently baked. During the final compacting movement of the die parts, 
the powdered ceramic is compacted above and below and around all sides of 
the inserted punches. The final dwell period enables the escape of 
essentially any remaining air and the setting of the compacted ceramic so 
that the subsequent withdrawal of the recess forming punches does not 
allow collapse or significant deformation of the resulting undercut 
recesses. 
In accordance with another modification of the concept utilizing the 
undercut recesses and cam surfaces and useful with thicker ceramic bricks, 
a central opening is provided in the recessed surface of the brick 
sufficient to accommodate the central sheet steel body of a weldable 
insert. A pair of projections incline from one surface of the central 
sheet steel body and away from each other in opposite directions from a 
transverse center line of the body. Each projection also extends from 
adjacent transversely opposite edges of the body to distal ends arranged 
to confront the openings of a pair of said undercutting recesses and to 
cammed and deformed thereinto as described herein. The recesses are spaced 
by said central opening and are also offset transversely from each other 
to facilitate manufacture of the brick as described in my copending 
application. Spacers at the edges of the body project from said one 
surface so as to seat on the bottom of the central opening of the brick 
when the insert and brick are interlocked by deformation of the inclined 
projections into the undercut recesses. The brick and insert combination 
may be used as described herein, or may be modified to enable preassembly 
of the brick and insert for welding to a substrate as disclosured in my 
copending application. 
Another modification utilizes a brick having a central opening for 
receiving the body of a weldable sheet steel insert having only one 
projection at one end arranged for insertion into a single undercut recess 
that extends into one end wall of the central opening. The opposite end of 
the insert frictionally engages the opposite endwall of the central 
opening at an interference fit to retain the insert frictionally within 
the opening. The assembled brick and insert is suitable for use with 
thicker bricks and may be handled and shipped as a unit until the insert 
is welded to a substrate. Once welded to the substrate, the insert is 
positively interlocked with the brick without dependence on the frictional 
engagement. 
Other modifications of the present invention utilizing the concept of a 
brick having a pair of spaced recesses undercutting one surface and 
particularly useful to provide a "solid" thin ceramic brick employ a 
hardened spring steel insert formed from sheet steel to provide a 
resiliently deformable body. A pair of projections at opposite ends of the 
body and inclined to mate with the undercut recesses have distal ends 
arranged to confront the openings of the recesses and to be inserted 
thereinto upon resilient deformation of the body. After the projections 
are inserted into the recesses, the body is released to return resiliently 
to its undeformed position and interlock with the brick. 
In one situation, the insert body is deformable either by being stretched 
or compressed endwise to align the distal ends with the openings of the 
recesses, whereupon the projections are forced into the confronting 
recesses. Upon release of the endwise deforming force, the insert returns 
resiliently to its undeformed condition to interlock with the brick. In 
another situation, the body of the spring steel insert is bowed 
resiliently to enable insertion of its projections into the openings of 
the recesses. Thereafter upon release of the bowing force, the insert 
returns to its undeformed condition to interlock with the brick. 
Still another modification provides an insert comprising multiple weldable 
parts, each having a projection readily insertable into one of each of a 
corresponding number of recesses undercutting a surface of the brick. The 
separate parts are arranged so that when inserted into their associated 
recesses, they have juxtaposed portions that can be cemented or welded 
together to prevent removal of the insert from the brick. Thereafter the 
brick and assembled insert may be welded to a substrate as described 
herein. In a preferred embodiment of the latter modification, the separate 
parts have interfitting snap-together portions that temporarily prevent 
their separation from the brick to facilitate handling and shipping of the 
assembled brick and insert parts. In either situation, after being welded 
to a substrate, the parts become permanently interlocked with the brick. 
Other advantages and uses of the present invention will be apparent from 
the following description and appended claims, reference being had to the 
accompanying drawings forming a part of this specification wherein like 
reference characters designate corresponding parts in the several views.

DETAILED SUMMARY OF THE INVENTION 
Referring to FIGS. 1-3, an aluminum oxide ceramic brick 10 of approximately 
one-inch thickness is illustrated having approximately four-inch by 
six-inch rectangular outer and inner parallel faces 11 and 12. A small 
diameter guide hole 13 for a welding rod 13a extends normally through the 
face 11 at a central location for approximately three-quarters of an inch 
and enlarges radially to provide a plane ceiling 14 of approximately one 
square inch for an essentially square or rectangular recess 15. From a 
pair of opposite edges of the ceiling 14, the side walls 16 of the recess 
15 converge toward a mid-plane along the guide 13 at approximately a 
thirty to forty-five degree angle and toward walls of the brick normal to 
surface 12 to define an insert receiving opening 22 into the recess 15, 
thereby to undercut opposite edges of the opening 22 at 24. 
A welding insert 17 may be formed from a mild steel or low carbon twelve 
gauge sheet steel blank to provide a V-base 18 having a central opening 19 
of somewhat larger diameter than the diameter of the guide hole 13, and a 
pair of diverging ends or prongs 20 adapted to project toward the ceiling 
14. The prongs 20 in the undeformed condition shown in FIG. 1 diverge at 
approximately 110.degree. from the apex of the V and are dimensioned to 
pass readily through the insert receiving opening 22 into the recess 15 
and into sliding engagement with the ceiling 14. The prongs 20 are 
dimensioned so that upon the application of force urging the insert 17 
toward the ceiling 14, their distal or outer ends will engage and slide 
along the extremely hard surface of the ceiling 14 and be deformed 
radially outwardly into the maximum diameter of the undercut recess 15, 
FIGS. 2 and 3, without appreciably scratching the hard material of the 
ceramic brick 10. The insert 17 will thus be mechanically interlocked 
rigidly with the brick 10, and the base 18 within the recess 15 will be 
spaced from the surface 12 approximately a sixteenth of an inch to enable 
formation of a molten pool 23 of welding rod material to connect the 
insert 17 and wall 21. The term "rod" as thus used and hereinafter will 
encompass elongated welding materials such as an electrically charged 
welding rod or wire used respectively in conventional arc or MIG welding. 
Thus the diameter of the guide hole 13 may be as small as 0.035 inches and 
no larger than one-eighth of an inch where MIG welding is available, or 
approximately three-sixteenths of an inch when required for guiding a 
conventional arc welding rod. 
The assembled brick 10 and welding insert 17 may be shipped to the location 
where it is intended to be welded to the steel wall 21 or other backing to 
be protected from abrasion. At the welding site, the brick 10 is placed 
with its inner face 12 adjacent to the wall 21. A welding rod 13a is then 
inserted into the guide hole 13 and guided thereby coaxially through the 
opening 19 and into contact with the steel wall 21 without touching the 
insert 17. The arc welding operation is then carried out conventionally, 
such that the heat of the arc melts the end of the rod 13a in contact with 
the electrically grounded wall 21 and forms a pool of molten welding 
material 23 that hardens to provide a welded bond around the hole 19 and 
between the insert 17 and the wall 21. 
If the recess 15 is rectangular, the undercuts 24 are provided along the 
opposite shorter ends, such that the long dimension of the ceiling 24 of 
the recess 15 is aligned with the long dimension of the brick 10. The 
inclined walls 16 of the recess 15 converge from the undercuts 24 to 
within approximately one-eighth of an inch from the inner face 12, then 
extend essentially normally to that face (except for a small draft angle 
required to facilitate removal of the mold parts) to define the insert 
receiving opening 22 into the recess 15 through the inner face 12. The 
aforesaid draft angle for the various embodiments illustrated herein will 
be nominal because immediately upon release of the molding pressure 
required to form the green brick, the newly formed and unfired brick will 
expand slightly to facilitate removal of the recess forming mold parts. 
It will be appreciated that the weldable brick may be readily used to line 
steel hoppers, chutes, or other conduits or surfaces that are accessible 
for welding through the guide holes 13. FIG. 3 illustrates a situation 
wherein the brick 10 may be provided with an undercut recess 15 opening at 
its inner face 12 as described above, but the guide hole 13 for the 
welding rod is eliminated. In lieu thereof, a hole 25 is burned or cut 
into the steel substrate 21 at the location where the weld is desired. The 
brick 10 with an interlocked insert 17 is then aligned with the hole 25. 
The weld between the insert 17 and substrate 21 is then completed by 
conventional arc or MIG welding from the exterior of the substrate 21 
through hole 25. In the FIG. 3 application, the central hole 19 in the 
insert 17 may also be eliminated. 
Referring to FIGS. 4-6, a modification of the invention that is 
particularly adapted for use with thin ceramic wearplates or bricks 
similar to the brick 10 of FIGS. 1-3, but "solid" and approximately a 
quarter of an inch in thickness. The brick 10 shown in FIGS. 4-6 may be 
provided with a small central guide hole 13 as in FIGS. 1 and 2, that 
equally spaces a pair of oppositely angled recesses 15 approximately two 
inches apart. For a rectangular brick 10 as in FIG. 1, the recesses 15 are 
preferably centered on a longitudinal midplane along the opening 13 and 
parallel to the longer edges of the brick. The transverse extent of each 
recess 15 is perpendicular to the longitudinal midplane and is 
approximately a half an inch, and each is defined by closely spaced 
parallel walls 26 and 27 proximate to and remote from the guide hole 13 
respectively. The wall 26 undercuts the surface 12 and inclines at 
approximately a 60.degree. angle to the surface 12 to a ceiling 14 
parallel to the surface 12. The ceiling 14 is preferably spaced about an 
eighth of an inch from the surface 12, i.e., one-half way between the 
surfaces 11 and 12. For thicker bricks of say one-half to an inch, the 
ceiling may be spaced approximately a quarter of an inch from the surface 
12. 
The weldable insert 17 may be stamped from the same type of sheet steel and 
gauge thickness as in FIGS. 1-3 to form a square or rectangular flat body 
18 having projections 20 at opposite edges that extend essentially 
perpendicularly from the plane of the body 18, FIG. 4, so as to be 
alignable with the openings of the recesses 15. The distal ends 28 of the 
projections 20 incline toward each other at an angle to the interior wall 
20a of the associated projection 20 that is slightly less than the 
aforesaid angle of inclination of the walls 26 and 27, thereby to provide 
clearance for the deformed and assembled projections 20 between the walls 
26, 27. In this regard, the latter walls are spaced sufficiently to freely 
receive the associated undeformed projections 20 therebetween, and the 
distal end of the outer wall 20b of each projection 20 is arranged to 
engage the extremely hard surface of the associated wall 27 when inserted 
into the recess 15. When the brick and insert are aligned as in FIG. 4 and 
forced toward each other, the projections 20 are cammed and deformed into 
the portion of the recess 15 undercutting the brick surface 12, thereby to 
interlock the brick and insert. Obviously the projections 20 are also 
dimensioned to extend adjacent to the ceiling 14, as in FIG. 5 when the 
brick and insert are assembled. 
It is apparent from the foregoing that an interlocked weldable insert and 
abrasion resistant ceramic brick are provided that avoids a central 
opening for the body 18 of the insert and thus enables the provision of a 
thin walled brick and wearplate having optimum shock or impact resistance. 
The small guide hole 13 is usually of no concern in regard to impact 
resistance and may be used to secure the brick to a weldable substrate as 
described in regard to FIG. 2. 
On the other hand, where optimum impact resistance is required, the guide 
hole 13 may be eliminated, FIG. 4. In that situation, the insert 17 is 
first welded to the substrate 21 at the location where it is desired to 
secure the brick, with the undeformed projections 20 extending from the 
substrate 21. Thereafter the brick is aligned with and forced against the 
insert 17 as described above to interlock the brick 10 with the insert 17 
that has been previously welded to the substrate. 
In a preferred application of the invention illustrated in FIGS. 4-6, prior 
to forcing the brick into interlocking engagement with the insert 17, the 
recesses 15 are filled with a soft but hardenable caulk, as for example a 
mixed epoxy resin or with an RTV silicone. The peripheral inner surface 12 
of the brick may also be coated with the caulk 29. Thereafter the brick 10 
and insert 17 are aligned as in FIG. 4 and forced together to deform the 
insert and effect the interlocking engagement as described above. As the 
brick is forced toward the insert to deform the projections 20 into the 
undercut recesses 15, the caulk in the recess 15 will be extruded around 
the projections 20 to completely fill all spaces between the latter and 
the sidewalls of the recesses. When the caulk hardens, it adheres to the 
brick 10 and the projection 20 to appreciably enhance the interlocking 
engagement and prevents return of the insert to its undeformed shape. 
Usually the brick will be welded to the substrate at a location adjacent to 
a previously installed brick. As each brick is forced into position, the 
caulking 29 around the peripheral edges of the brick 10 will be flattened 
to fill the space 31 between the brick and substrate caused by the 
thickness of the body 18. Also the caulking 29 will be extruded at 32 
between the juxtaposed bricks 10 and should be wiped clean from the brick 
surfaces 11 to complete the job. 
Referring to FIGS. 7 and 8, a modification of the invention more 
particularly suitable for use with thicker bricks provides an essentially 
rectangular opening 33 in the surface 12 of the brick 10. Opposite walls 
34 of the recess 33 extend essentially perpendicularly to the surface 12 
and are provided with recesses 15 that diverge oppositely from each other 
at approximately 30 degrees to the surface 12. The recesses 15 extend 
approximately a quarter of an inch beyond the surfaces of the walls 34 and 
open thereat approximately an eighth to a quarter of an inch below the 
surface 12. 
The weldable insert 17 may likewise be formed from a sheet steel blank of 
the type described in regard to FIG. 1, but comprises two identical and 
essentially rectangular body parts 18a, each rotated 180 degrees with 
respect to the other around the axis of the guide hole 13. Each insert 
body 18a is provided with a single projection 20c adapted to fit freely 
within one of the recesses 15 offset transversely from each other on 
opposite sides of the longitudinal midplane of the brick along the guide 
opening 13 in order to facilitate fabrication as disclosed in my copending 
application. The separate insert parts 18a when inserted into opening 33 
and into their respective recesses 15 provide confronting edges 35 spaced 
apart sufficiently to facilitate assembly of the parts 18a within their 
respective recesses. The confronting edges 35 also provide semicircular 
recesses 36 that cooperate to provide a welding hole coaxial with the 
guide hole 13. Preferably an annular spacer 37 is arranged coaxially with 
the opening 13 in position underlying the body parts 18a to hold the same 
essentially in parallelism with the surface 12 until the separate parts 
18a are secured together, either by cementing or spot welding at 38. Once 
the parts 18a are secured together, they cannot be removed from the 
opening 34. Preferably the surfaces of the parts 18a proximate the surface 
12 are spaced from the latter within the opening 34 to provide space for a 
pool of molten weld material 23 when the brick is secured to the substrate 
21 as described above. 
Referring to FIGS. 9-11, another modification employing a weldable insert 
formed from two separate identical sheet steel stampings is illustrated. 
Each separate stamping comprises a flat body 18b having a projection 20 at 
one end capable of being freely inserted into one of a pair of undercut 
recesses 15 in the brick 10 and being frictionally interengagable with the 
other separate stamping, shown in phantom in FIG. 9, to prevent their 
accidental separation from the brick until they are permanently welded 
together by being welded to a substrate. The brick 10 is provided with a 
central circular opening 33 for freely receiving portions of the inserts, 
and the usual guide hole 13 where desired. The opening 33 spaces the 
recesses 15 inclined toward each other so as to undercut the brick surface 
12, FIG. 10. 
Extending from each body 18b and away from its projection 20 are a pair of 
plates or leaves 41 and 42 spaced by a slit 43 that extends along the 
longitudinal midplane of the body 18b from the end thereof opposite the 
projection 20 and terminates at a rounded end 46 near the projection 20. 
The plate 42 comprise an overlapping leaf that extends arcuately at 42a 
approximately 90.degree. away from the opening of the slit 43, then 
radially at 42b to the adjacent edge 42c of the body 18b. That edge 
extends parallel to the longitudinal midplane essentially to the 
projection 20 where it narrows at 47, then extends to one transverse end 
of the projection 20. The plate 41 comprises an underlying leaf that 
extends arcuately at 41a away from the slit 43, but at a larger radius 
than 42a, for a little less than 90.degree. to the adjacent edge 41c of 
the body 18b. The latter edge extends parallel to the edge 42c toward the 
projection 20, narrows at 48, then extends to the other transverse end of 
the projection 20. The leaf 41 is also offset at 41d an amount 
approximately equal to the sheet metal thickness of the body 18b so as to 
lie freely within the opening 33 when the separate parts 18b are assembled 
with the brick 10. 
The two identical weldable parts are rotated 180.degree. with respect to 
each other so that the plates 41 and 42 may be closely interleaved in 
frictional contact with each other, with each plate 42 of one stamping 
overlying the underlying plate 41 of the other stamping. To facilitate 
welding to a substrate 21 as described above, each part 41 and 42 is 
provided with a circular recess 43a opening at the slit 43 to provide a 
hole for passage of a welding rod. The two interleaved stampings may be 
slidably elongated prior to assembly with the brick 10 until the 
extensions 20 overlie their respective recesses 15, then as the extensions 
20 are moved into their recesses 15, the extensions will simultaneously be 
moved toward each other by sliding the interleaved plates 41, 42 toward 
the final assembled position, FIG. 13. 
In FIGS. 9-11, the undercut recesses 15 are appreciably wider than 
necessary to receive the sheet metal thickness of the projection 20. The 
latter is provided with an extension 51 parallel to the surface 12 and 
dimensioned to fit adjacent to a mating parallel surface 52 defining the 
base of the recess 41. Thus the assembled and interleaved parts 41, 42 of 
the weldable insert cannot shift endwise and permit loosening of the 
frictional engagement therebetween. As noted in FIG. 10, the opening 33 
may be deeper than necessary to receive the plates 41, thereby to provide 
an air space between the bottom of the opening 33 and the plates 41 to 
shield the ceramic from the direct heat of the welding operation. 
FIGS. 12-14 show a modification of a deformable weldable insert 17 for use 
with a ceramic brick of the type illustrated in FIG. 8. The insert 17 is 
stamped from a sheet metal blank as described above to provide a flat body 
18c having an opening 36a alignable with the guide hole 13 through the 
brick. In this case the hole 36a is elongated in the direction of the 
longitudinal midline of the brick in order to accommodate dimensional 
tolerances in the insert 17 that might result in its shifting 
longitudinally when the brick and insert are assembled. The body 18c is 
provided with a pair of oppositely directed transversely offset 
projections 53 that incline away from each other at approximately 
120.degree. to distal ends 54 arranged for alignment and insertion into 
correspondingly offset recesses 15. The juncture of each projection 53 
with the body 18c is coined at 55 to provide a line of weakness to 
facilitate deformation of the projections 53 to the plane of the body 18c 
when the latter is assembled with the brick 10. Each projection 53 is 
spaced from the body 18c by a slit 56, and the two slits 56 associated 
with the projections 53 respectively extend parallel to the longitudinal 
midplane in opposite directions from adjacent to the transverse midline of 
the body 18c, such that the two projections 53 are offset transversely 
from each other as well as arranged to extend in opposite directions. 
The opposite transverse edges of the body 18c provide flanges 57 that 
extend perpendicularly from the plane of the body 18c (in the same 
direction that the projections 53 extend) to provide spacers adapted to 
extend adjacent to the ceiling 14 of the recess 33 when the brick 10 and 
insert 17 are assembled. As illustrated in FIG. 13, the distal ends 54 are 
alignable with the openings of the recesses 15 and are provided with cam 
surfaces 58 arranged to slidably engage a mating cam surface 59 comprising 
one wall of the insert 15 and deform the ends 54 into the recess 15, as 
illustrated in FIG. 14, when the projections 53 are deformed into the 
plane of the body 18c. At the deformed position of the projections 53, 54, 
the spacer 57 will be adjacent to the ceiling 14 of the opening 33 to 
maintain the outer surface of the body 18c adjacent to but spaced slightly 
from the brick surface 12 to permit the accumulation of a pool of molten 
welding material 23 when the insert is welded to the substrate 21 as 
described above. 
The structure of FIGS. 12-14 is partially adapted for use where the insert 
17 is first welded to the substrate. Thereafter the brick 10 is forced 
against the projections 53, 54 to deform the latter into the recesses 15 
as described above. If the insert is to be welded to the substrate 21 
before being assembled with the brick, the guide hole 13 may be 
eliminated. If the insert 17 is not welded first to a substrate, the 
spacers 57 provide an air gap spacing the ceramic from the direct heat of 
the welding that then utilizes the welding rod guide hole 13. 
FIGS. 15 and 16 illustrate a modification of the concept described in 
regard to FIGS. 4-6 wherein a brick provided with a pair of recesses 15 
undercutting the inner surface 12 of the ceramic block 10 at diametrically 
opposite sides of the guide hole 13 receive the correspondingly inclined 
projections 20 upon deformation of the weldable insert 17. In this case, 
the insert 17 is stamped from a soft white sheet steel blank capable of 
being hardened by heat treatment to provide a resiliently deformable 
spring steel insert having a flat base 18 spacing the projections 20 
dimensioned to fit within their associated recesses 15 and to underlie the 
surface 12 at their distal ends when the insert 17 is in its undeformed 
shape. 
The brick 10 and insert 17 are assembled by inserting the projection 20 at 
one end into one of the recesses 15, such that the other projection 20 
will rest on a portion of the surface 12 undercut by the other recess 15. 
Thereafter the base 18 is bowed toward the surface 12 by the application 
of force in the direction of the arrow 61, FIG. 16, so as to enlarge the 
included angle 62 between the undeformed projection 20 and base 18 and 
spread the distal end 28 of the projection 20 associated with the enlarged 
angle indicated at 63 to the extent that the end 28 may be forced into the 
opening of the recess 15. 
In FIG. 16, the distal end 28 is on the verge of moving into the adjacent 
recess 15 and will move into that recess when the bowing force 61 is 
increased slightly. Thereafter the resiliently yieldable spring steel 
insert 17 will snap back to its undeformed condition to interlock both 
projections 20 within their respective recesses 15, preferably at a slight 
interference fit. In FIGS. 15 and 16, the distance between the parallel 
inclined walls 26 and 27 is dimensioned to freely receive the inserts 20. 
Additional interlocking effectiveness and total elimination of lost motion 
between the brick 10 and insert 17 may be enhanced by filling the recesses 
15 with a hardenable caulk as described above. 
FIGS. 15 and 16 illustrate a comparatively thick brick 10 having a central 
guide hole 13 for enabling welding to a substrate as in FIGS. 3 and 6. In 
the assembled position, the flat body 18 lies essentially flush with the 
surface 12 except for production tolerances, and an annular weldable 
reinforcement 64 underlies the base 18 within a bowl shaped opening 65 in 
the brick face 12 coaxially with the guide hole 13 and insert hole 19. 
Thus when the base 18 is welded around the opening 19 to a substrate 21 as 
in FIG. 3, the welding pool will also weld the reinforcement 64 to the 
base 18 to rigidize the central portion of the insert 17. 
The concept of FIGS. 15 and 16 may also be employed with a brick having a 
thickness approximating a quarter inch. In that event, the reinforcement 
64 and recess 65 may be eliminated. The bowl shaped recess 65 is effective 
to space the adjacent surface of the brick 10 from the direct heat of the 
welding to a substrate. 
FIG. 17 illustrates a modification somewhat on the order of FIGS. 7 and 8 
wherein the side walls 34 of the opening 33 for the body of the insert 17 
diverge at approximately a 30 degree angle therebetween, i.e., 
approximately 15 degrees with respect to the axis of the guide hole 13, 
and the recess 15 undercutting the brick surface 12 extends into only one 
of the end walls 34. The insert 17 of FIG. 17 is stamped from a sheet 
steel blank as described in regard to FIG. 1 to provide a flat base 18 and 
a single projection 20 at one end inclined from the base 18 at the same 
angle that the parallel side walls of the insert 15 incline from the 
surface 12. The projection 20 is freely insertable into the opening of the 
recess 15 before the opposite end 20a enters the opening 33. The latter 
and insert 17 of FIG. 17 are dimensioned so that upon insertion of the 
projection 20 to the limit of movement into the recess 15, the end 20a can 
be forced into the opening 33 into frictional engagement with the adjacent 
inclined end wall 34 to temporarily lock the insert 17 within the opening 
33. Thereafter when the insert 17 is welded at 23 to the substrate 21 as 
described above, the brick and insert are permanently interlocked without 
dependence upon the frictional engagement. 
FIGS. 18-20 are directed to a modification of the concept of a resiliently 
yieldable insert 17 of the type described in regard to FIGS. 15 and 16. 
The insert 17 of FIGS. 18 and 20 is formed from a sheet steel blank 
comparable to the blank from which the FIGS. 15, 16 insert is formed and 
is thereafter heat treated to provide a resilient spring steel insert. In 
this case, the flat body 18 is provided with a transversely elongated 
opening 19 to enable welding as described above and also to facilitate 
longitudinal stretching of the insert 17 within the limit of its 
elasticity for about an eighth of an inch. At each of the opposite sides 
of the opening 19, the body 18 may be provided with a pair of transversely 
opening slits 66 that extend to approximately the longitudinal midline of 
the insert 17. Endwise of the slits 66, the body 18 is provided with the 
projections 20 inclined toward each other at angles parallel to the side 
walls 26 and 27 of the undercutting recesses 15. The recesses 15 are 
located to freely receive one or the other of the projections 20 of the 
undeformed insert 17 and the projections 20 are arranged to snugly engage 
the inclined recess walls 26 at a slight interference fit when the brick 
10 and insert 17 are assembled. 
The assembly is accomplished by inserting one projection 20 into one of the 
recesses 15 and thereafter to stretch the recess longitudinally by means 
of a forked tool 67 having a pair of prongs 68 engagable within the slits 
67 adjacent to the other projection 20 to be inserted into the other 
recess 15. By moving the tool 67 in the direction of the horizontal arrow, 
FIG. 20, the insert 17 may be stretched longitudinally within the limits 
of its elasticity by reason of the elongated opening 19 and slits 66, and 
then forced into the aforesaid remaining recess 15, FIG. 20. Upon removal 
of the tool 67 and the stretching force, the insert 17 of FIGS. 18-20 will 
return resiliently essentially to its undeformed condition with the 
projections 20 snugly engaging the walls 26, again preferably with an 
interference fit of a few hundreths of an inch. Again, for use with 
one-quarter inch bricks, the bowl 65 and spacer 64 may be eliminated. 
Also, where the welding is to be performed as described in regard to FIG. 
3, even the guide hole 13 may be eliminated. Where the insert has 
sufficient resiliency to enable the stretching within the elastic limits 
of the insert, without reliance on the slots 66, these may be eliminated. 
The elongated hole 19 will then enable the stretching and resilient return 
to the undeformed condition. 
FIGS. 21-25 illustrate various steps in the sequence of forming a green 
unbaked ceramic brick embodying the present invention. The molding 
apparatus schematically illustrated comprises cooperating male and female 
die assemblies 71 and 72 respectively conventionally operated 
hydraulically to compress conventional dry powdered ceramic to the brick 
shape. The die assembly 72 provides an upwardly opening die or mold cavity 
73 having vertical sidewalls arranged to form the edges of the brick 10. 
The bottom of the mold cavity 73 is defined by a vertically movable bottom 
plunger 74 having a plane surface for forming the surface 11 of the brick 
10. The plunger 74 slides in sealing relationship along a centrally 
located rod 75 dimensioned to form the guide hole 13 and secured at its 
lower end to a fixed bottom portion 76 of the mold assembly 72. 
The male die assembly 71 comprises a male die plunger 92 having a plane 
bottom surface portion 93 for forming the plane flat surface portion 12 of 
the brick 10. The central bottom portion of the plunger 92 may provide a 
central bulge 94 for forming the bowl 65 in the brick surface 12. 
Extending upwardly into the center of the plunger 92 is a small diameter 
elongated recess 95 for reception of the upper end of the spindle or rod 
75. 
A pair of punches 102 supported angularly within the male plunger 92, 
preferably at oppositely directed angles of incidence of approximately 60 
to the surface 93, are dimensioned to form the undercutting recesses 15 
and may be forced approximately an eighth of an inch or more into the 
partially compacted ceramic as described below. Each of the punches 102 is 
connected by a rod 105 to a double acting piston 103 reciprocal within a 
cylinder 104 contained within the body of the plunger 92. The pistons 103 
are hydraulically actuated simultaneously by hydraulic fluid supplied 
conventionally through hydraulic lines 106 and 107, FIG. 21. 
While the punches 102 are withdrawn into the body of the male plunger 92 
and flush with the surface 93, and the plunger 92 is at the raised 
starting position of FIG. 21, the die cavity 73 is filled with an amount 
of loose dry powdered ceramic 78, FIG. 22, required for formation of a 
compacted green brick. Thereafter, with the punches flush with surface 93, 
the plunger 92 is moved to a preliminary or partially compacting position 
into the die cavity 73 with sufficient force to compact the particles of 
the loose powdered ceramic together and expel most of the air therefrom. 
In this regard, the plunger 92 is dimensioned to seal the upper opening of 
the cavity 73 sufficiently to prevent extrusion of the powdered ceramic 
around the periphery of the plunger 92 during the final high tonnage brick 
forming pressure, but with sufficient clearance to allow the escape of air 
pressed from between the ceramic particles. 
After the conventional momentary dwell period at the partially compacted 
FIG. 22 position, i.e., sufficient to enable the partially compacted 
powdered ceramic to attain an equilibrium condition as air is pressed from 
between the ceramic particles and escapes from the cavity 73 around the 
periphery of the plunger 92, hydraulic lines 107 and 106 are connected 
respectively to high pressure and to a low pressure return, thereby to 
drive the pistons 103 downwardly and force the punches 102 angularly into 
the partially compacted ceramic to form the recesses 15, FIG. 23. 
Thereafter the hydraulic compacting force is again applied, as for example 
by raising the bottom plunger 74 to the final high tonnage compacting 
position of FIG. 24. The final compacting force is maintained for the 
momentary dwell period as customarily required in the formation of ceramic 
bricks, i.e. sufficient to enable the compacted ceramic to attain an 
equilibrium condition as the residual air is expressed from between the 
ceramic particles by the final high tonnage pressure and escapes around 
the periphery of the plunger 92. Thereafter the pistons 103 are returned 
to the retracted FIG. 21 position by connecting the hydraulic lines 106 
and 107 respectively to high pressure fluid and to the low pressure 
return, thereby to retract the punches 102 from the formed green brick. 
The molding pressure is then immediately relieved by returning plunger 92 
to the FIG. 21 starting position, and the newly formed green brick is 
ejected from the mold. 
Alternatively, the plunger 92 may be provided with the plane surface of 
plunger 74 and the plunger 74 may be provided with the surfaces 93 and 94 
of plunger 92. In that event, after the final high tonnage compacting is 
applied between the modified plungers 92 and 74, and after the customary 
dwell period, the final compacting force may be relieved by elevating the 
modified plunger 92 prior to retraction of the punches 102. Thereafter the 
punches 102 will be retracted and the newly formed green brick will be 
ejected from the mold. 
The operating sequence described, including the customary momentary dwell 
periods, formation of the recesses 15 in the partially compacted ceramic 
at the preliminary position of FIG. 23, and thereafter compacting the 
ceramic to the final high tonnage pressure, enables the punches 102 to be 
withdrawn from the compacted brick without causing collapse or deformation 
of the recesses 15. The withdrawal of plunger 92 from the cavity 73 
immediately releases the pressure on the green brick 79 and avoids any 
tendency for the compacted ceramic to fill in the newly formed recesses 
15.