A corrugator for receiving plastic from an extruder and continuously molding corrugated plastic tile therefrom. The corrugator has a plurality of mold assemblies which are continuously driven to roll about an endless trackway on the corrugator frame, a portion of which defines a molding section. Each mold assembly includes a pair of mold blocks mounted to pivotally open and close. As the mold assemblies enter the molding section, the mold blocks thereof pivotally close and come into abutting relationship with the closed mold blocks of preceeding mold assemblies to cooperatively form a corrugated molding tunnel. Extruded plastic is received by the molding tunnel which moves with and molds the corrugated tile. At the end of the molding section the mold blocks pivot away from and release the tile. To augment the formation the tile the mold blocks are cooled. Additionally a vacuum is induced between the extruded plastic and the wall of the molding tunnel to assure the mating thereof.

BACKGROUND OF THE INVENTION 
1. Technical Field 
This invention relates to machines which transform extruded thermoplastic 
into a corrugated plastic tile and more particularly to machines which can 
be continuously form corrugated plastic tiles. 
2. Description of the Prior Art 
Due to the utility of corrugated plastic tiles particularly as buried 
drainage conduits, a need has arisen for devices which can continuously 
mold lengths of corrugated plastic tiles. 
One such type of device is found in U.S. Pat. No. 3,981,663 issued Sept. 
21, 1976 to Lupke. Acting in conjunction with a thermoplastic extruder 
which continuously dispenses a cylindrical tube of heated, pliable 
plastic, the corrugator has upper and lower mold assemblies each of which 
consists of endless chains of mold blocks. Synchronously driving the upper 
and lower mold assemblies causes the individual mold blocks thereof, with 
the aid of aligning pins, to mate and run together for a portion of the 
corrugator to form a tunnel defining a tubular mold which receives, moves 
with and molds the dispensed thermoplastic. At the end of the molding run 
the mold blocks are drawn substantially radially away from the molded 
corrugated tile so as not to damage the corrugations formed thereby. 
One of the drawbacks of corrugators heretofore used and particularly of the 
type described above is that they tend to be quite large and therefore 
require large areas of dedicated space. One of the primary factors 
contributing to the size of the machine is the requirement that the mold 
blocks be drawn substantially radially away from the tile at the end of 
the molding operation so that the corrugated surfaces of the mold blocks 
do not engage and thereby damage or distort the corrugations. 
Another drawback of note is the method by which the mold blocks of the 
upper and lower mold assemblies are matingly brought together to form the 
tunnel in which the corrugated tile is molded. Synchronous drives for both 
the upper and lower mold assemblies are required along with aligning pins 
on individual mold blocks to assure that the mold blocks properly mate to 
form the molding tunnel. Occasional slack, induced upon the chains 
carrying the mold blocks by wear, may result in the failure of the mold 
blocks to properly come together thereby creating random seams or the like 
along the corrugated tile or, if the amount of slack is great enough, 
shearing off the aligning pins on the mold blocks necessitating stopping 
of the corrugator for replacement thereof. 
Yet a further drawback of corrugators heretofore used is that the driving 
motors, due to the friction between the mold blocks, their interconnecting 
chains and the frame, must be of substantial horsepower to drive the mold 
assemblies. 
It is an object of the present invention to overcome the drawbacks of 
corrugators heretofore used particularly those drawbacks set forth above. 
SUMMARY OF THE INVENTION 
Toward this end a tile corrugator is set forth having a plurality of 
independent, rolling, mold assemblies each of which is composed of 
pivotally opening and closing mold blocks. When closed the mold blocks 
cooperate to define a segment of a corrugated tunnel which receives 
thermoplastic from the extruder for the formation of the corrugated tile. 
The mold assemblies are received, guided by and roll along an endless 
trackway about the frame of the corrugator, a portion of which defines the 
molding section of the corrugator. A drive means engages the mold 
assemblies at a location on the frame to circulate them about the 
trackway, the mold assemblies particularly at the molding section of the 
corrugator pushing one another in abutting relationship. A pivoting means 
causes the mold blocks to pivotally close as they sequentially enter the 
molding section. Thereafter, the mold blocks, in cooperation with the mold 
blocks of adjoining mold assemblies, form a corrugated tunnel which 
receives the extruded thermoplastic and moves therewith to form the 
corrugated plastic tile. As the mold assemblies leave the molding section 
the pivoting means opens the mold blocks away from the tile yielding a 
corrugated plastic tile. The mold assemblies thereafter return for 
re-entry into the molding section of the corrugator. Further augmenting 
the formation of corrugated tiles, the corrugator has a cooling means to 
cool the mold assemblies and thereby the thermoplastic to enable operation 
of the corrugator at speeds heretofore unknown. Additionally, vacuum means 
communicating with the mold tunnel assures that the dispensed 
thermoplastic fills the mold blocks for proper formation of the corrugated 
tile. 
Accordingly it is an object of the present invention to provide a 
thermoplastic tile corrugator which is smaller than those heretofore used. 
The novel pivotally opening and closing mold blocks radially disengage the 
molded tile without requiring long runs to gradually draw the mold blocks 
from the tile. 
It is a further object of the present invention to provide a tile 
corrugator which is simpler in operation than those heretofore used. No 
synchronous drives nor aligning pins are required to assure or maintain 
proper alignment of the mold blocks for correct molding of the corrugated 
tile. 
It is yet another object of the present invention to provide a tile 
corrugator which uses a relatively small driving motor. The structure 
reduces friction between the rolling mold assemblies and the frame 
avoiding large horsepower requirements to circulate the mold assemblies 
about the frame. 
It is still a further object to provide a novel method for manufacturing 
corrugated plastic tile including cooling of the mold assemblies and 
inducing a vacuum between the plastic and the mold blocks to assure proper 
molding thereof. 
Further objects and advantages of the present invention will become 
apparent upon a reading of the specification, drawings and attached claims 
.

DESCRIPTION 
Turning to FIGS. 1-3 a tile corrugator 10 of the present invention is 
shown. The corrugator 10 has a base 12 defined by a pair of side beams 14 
having secured thereto a front beam 16 and a rear beam 18. Upstanding from 
the side beams 14 are a plurality of complementary pairs of braces 20. The 
complementary braces 20 are in turn mutually supported by a cross-member 
22 and a pair of spaced upper and lower ties 24 and 26. For purposes which 
will hereinafter become evident the upper and lower ties 24 and 26, are 
parallel and are arranged to be co-planar with their counterparts on the 
other braces 20. A pair of vertical supports 28 span each pair of upper 
and lower ties 24 and 26 to provide additional support thereto, and to the 
remainder of the frame. Accordingly the aforementioned structure provides 
a sturdy frame for the remainder of the tile corrugator 10 hereinafter set 
forth. 
Extending from the front of the corrugator 10 to the rear thereof (right to 
left as illustrated in FIG. 1) are forward and return track assemblies 30 
and 32. The forward track assembly 30 is secured upon the upper ties 24 
and provides a rolling trackway the purposes of which will hereinafter 
become evident. Accordingly, the upper track assembly 30, as best shown in 
FIG. 4, has a pair of parallel track supports 34 which are secured to the 
upper ties 24. The track supports 34, which provide additional support to 
the frame, have secured thereon forward runners 36. Positioned upon the 
forward runners 36 are a pair of forward rails 38 maintained in a spaced 
relationship by a spacer 42. The forward rails 38 and spacer 42 are 
secured to the forward runners 36 and track supports 34 by, for example, a 
plurality of bolts 44 which pass therethrough. The opposing longitudinal 
cavities between the forward rails 38 defines forward trackways 46. 
Turning to FIG. 5 the return track assembly 32 is shown in detail. In a 
manner similar to the forward track assembly 30 the return track assembly 
32 consists of a pair of spaced, parallel track supports 34 which are 
secured to and suspend from the lower ties 26. Attached to the track 
supports 34 are return runners 48 which have secured thereto, by bolts 44, 
return rails 50 spaced apart from return runners 48 by spacers 42. In a 
manner similar to the forward track assembly 30, the cavities between the 
return runners 48 and return rails 50 define return trackways 52. 
To provide transition between the forward and return trackways 46 and 52, 
pairs of front and rear members 54 and 56 are secured to the upper and 
lower track supports 34. The front members 54, shown to the right in FIG. 
1, have semicircular front trackways 58 which are similar to and whose 
ends mate with the forward and return trackways 46 and 52 thereby 
providing a continuous transition therebetween. The rear members 56 
likewise have semicircular rear trackways 60 which are similar to and 
whose ends mate with the forward and return trackways 46 and 52 to provide 
a continuous transition therebetween. Accordingly, the forward and return 
trackways 46 and 52 along with the front and rear trackways 58 and 60 
described above provide an endless track about the corrugator 10, 
preferably with relatively long horizontal runs one above the other. 
Supported and guided by the above described trackways for rolling action 
therealong are a plurality of mold assemblies 70. In that all mold 
assemblies 70 are alike, only one will be described in detail. As best 
seen in FIGS. 4-6 each mold assembly 70 has a supporting carriage 72 with 
a body 74 supporting a pair of eyelets 76 shown as upstanding in FIG. 4. A 
pair of opposing sides 78 of the body 74 support coaxial pairs of 
outwardly extending axles 79 on the ends of each of which are journaled 
rollers 80. The disposition of the four spaced rollers 80 provides a 
stable support the remainder of the mold assemblies 70. The rollers 80 are 
adapted to be received by and freely roll within the trackways thereby 
enabling the mold assemblies 70 and more particularly their carriages 72 
to roll therealong. 
To maintain the mold assemblies 70 in mutual alignment and to assure that 
their carriages 72 properly roll within the trackways, a guide 82 is 
positioned upon the upper and lower ties 24 and 26 between the track 
supports 34. The guide has a pair of spaced walls 84 which define a 
guideway 86. In a like manner the front and rear members 54 and 56 support 
guides and their guideways (not shown). Disposed transverse to the 
carriage body 74 for reception by and rolling action within the guideway 
86 is a guide roller 88. 
From the above and viewing the drawings it can be seen that the mold 
assemblies 70 are able to roll about the corrugator trackway in that the 
carriage rollers 80 are received into and roll along the endless trackway. 
The aforementioned rolling of the mold assemblies 70 is guided by the 
rolling of their guide rollers 88 within the guideway 86. 
Secured between the eyelets 76 of each mold assembly 70 is a pivot shaft 94 
which pivotally mounts a right and a left mount 96 and 98. The right and 
left mounts 96 and 98 consist of a pair of pivot arms 100 which are 
pivotally mounted to the pivot shaft 94 and to a mounting plate 102. 
Affixed to the outward edges of the mounting plates 102 are L-shaped 
brackets 104. Opposing the brackets 104, each mounting plate has a 
retainer 106 the outwardly facing edge of which forms, in cooperation with 
the mounting plate 102, and angular groove 108. 
Removably mounted to the plates 102 of each of the right and left mounts 96 
and 98 are, respectively, right and left mold blocks 110 and 112. As seen 
in the drawings, particularly FIGS. 4, 5, 8 and 9 the right block 110 is 
semi-cylindrical having a corrugated inner wall 114 formed by alternating 
grooves 116 and lands 118. Opposite the inner wall 114, the right mold 
block 110 has a finned outer wall 120. Extending between the inner and 
outer walls 114 and 120 are flat forward and rear end faces 122 and 124, 
respectively, which as shown in FIG. 8 intersect the inner wall 114 
medially of a groove 116 thereon. Orthogonal to the forward and rear end 
faces 122 and 124 and extending therebetween are upper and lower edges 126 
and 128. Additionally, extending orthogonally between the forward and rear 
end faces 122 and 124 and formed along the outer wall 120 is a top face 
130 which, for reasons hereinafter evident, is planar and parallel to the 
forward trackway 46 when the mold blocks are closed as shown in FIG. 4. 
To removably mount the right mold block 110 to the mounting plate 102, the 
right mold block 110 has extending outwardly from the outer wall 120 
thereof a wedge member 132 and a mounting arm 134. The wedge member 132 is 
disposed along the bottom of the right mold block 110 and is adapted to be 
received and held by the angular groove 108 as best shown in FIG. 4. The 
arm 134, acting in cooperation with the wedge member 132, mates with the 
bracket 104 and is secured thereto as by bolts. Accordingly it is to be 
understood that by disposing the wedge member 132 within the angular 
groove 108 and securing the arm 134 to the brackets 104 removably affixes 
the right mold block 110 to the plate 102 of the right mount 96. 
The left mold block 112 and its plate 102 are a mirror image of the right 
mold block 110 and plate 102 and the means for securing the left mold 
block 112 to its respective left mount 98 is the same as the method 
described above. Viewing FIG. 4 it is seen that when the mold blocks are 
in the closed position the upper and lower edges 126 and 128 thereof mate 
to form a corrugated molding tunnel 136. 
To provide a means to drive the mold assemblies 70 and more particularly 
their carriages 72 about the trackways a pair of spaced sprockets 138 are 
provided between the front members as shown in FIGS. 1 and 2. The 
sprockets 138 include a web 140 having secured thereto and radially 
outward extending therefrom a plurality of tongues 142. The tongues 142 of 
each sprocket 138 are adapted sequentially engage the axles 79 of the mold 
assemblies 70 as they leave the return trackways 52, drive the mold 
assemblies 70 upward along the front trackways 58 to and disengage them at 
the forward trackways 46. Due to the number of mold assemblies 70 within 
the trackway and the rolling friction therebetween, the mold assemblies 70 
and more particularly their respective mold blocks are, along the forward 
track, in abutting relationship as best shown in FIGS. 1 and 7. This 
relationship is maintained as the continuous supply of mold assemblies 70 
delivered to the forward trackway 46 by the sprockets 138 pushes the mold 
assemblies therealong as substantially shown in FIG. 1. 
To drive the sprockets 138 shown in FIG. 1 a sprocket motor 144 is 
provided. The sprocket motor 144 drives a chain 146 which, in turn, drives 
the sprockets 138. Accordingly, operating the sprocket motor 144 which 
preferably is of the variable speed type, rotates the sprockets 138 which, 
in turn, drives the mold assemblies 70 for circulation about the endless 
trackway. 
For proper operation of the corrugator 10, the mold blocks of the mold 
assemblies 70 must pivotally close as they enter the forward trackway 46 
to form the molding tunnel 136. Accordingly, and as best shown in FIGS. 4 
and 5 each mold assembly 70 has a pair of opposing follower axles 148 
extending outwardly from the brackets 104. Journaled upon the ends of the 
follower axles 148 are roller bearings which define followers 150. 
Cooperating with the followers 150 to open and close the mold blocks are a 
pair of cam surfaces 152 disposed above and along the forward track 
assembly 30. Each cam surface 152 consists of a forward and a rear sloping 
surface 154 and 156 and a plateau 158 therebetween, the plateau 158 being 
parallel to the forward trackway 46 and defining thereby the molding 
section of the corrugator 10. As the mold assemblies 70, driven by the 
sprockets 138, approach and initiate rolling along the forward trackway 
46, the followers 150 engage and roll along the cam surfaces 152 and more 
particularly the relatively short forward surfaces 154 thereof. In so 
doing the interaction of the followers 150 and the forward surfaces 154 
induces a moment upon the pivoting right and left mold blocks 110 and 112 
causing them to simultaneously close. Upon reaching the plateaus 158, the 
closing action of the mold blocks is complete and, as shown in FIG. 4, the 
upper and lower edges 126 and 128 thereof have mated to form, with the 
preceedingly closed mold assemblies 70, a continuous molding tunnel 136 
extending the length of the molding section (see FIG. 1). It is in this 
section of the corrugator, as described below, where thermoplastic 
continuously is received and molded into a corrugated tile. 
Leaving the molding section, the followers 150 engage and roll along the 
rear surfaces 156 thereby causing the right and left mold blocks 110 and 
112 of each mold assembly 70 to pivot and radially open from the tile. The 
following of the rear surfaces 156 and the concomitant opening of the mold 
blocks is due to the off-center pivotal mounting of the mold blocks to the 
pivot shaft 94. Leaving the cam surface 152 and more particularly the rear 
surfaces 156 thereof, the mold blocks are in the open position shown in 
FIGS. 2 and 5. 
To maintain the mold blocks in the open position along the return trackway 
52 for cooling thereof, as described in detail below, the braces 20 
support opposing projections 160 which, in turn, angularly mount opposing 
shelves 162. As best seen in FIG. 5 the followers 150 roll along the 
shelves 162 thereby maintaining the mold blocks in the open position 
throughout the extent of the return trackway 52. To accommodate the 
foregoing without interference, the return rails 50 are appropriately 
beveled. 
The front and rear members 54 and 56 likewise support shelves (not shown) 
to assure that the mold assemblies 70 roll therealong in the open 
position. 
As stated above the thermoplastic is received by the mold tunnel 136 for 
the formation of corrugated tile therefrom. The thermoplastic, as 
received, is at some elevated temperature, depending upon the plastic used 
in order to make the thermoplastic pliable and thereby susceptible to 
molding. Therefore, means are required to cool the thermoplastic 
particularly along the molding section of the corrugator 10. Accordingly, 
cooling air is supplied to the corrugator 10 from a blower (not shown) 
through a supply duct 164. Communicated with the duct 164 are a pair of 
side plenums 166 and a bottom plenum 168. As best seen in FIGS. 3 and 4 
each of the side plenums 166 communicates with and supplies cooling air 
through exhaust plenums 170 extending along the molding section and which 
are directed inwardly toward the mold blocks. Cooperating with the exhaust 
plenums 170 are a pair of arcuate shields 172 spaced from and directing 
the flow of cooling air around the mold blocks. The shields 172 are spaced 
from one another near the top of the mold assemblies 70 (as seen in FIGS. 
3 and 4) to define an exhaust 174 for cooling air. It follows that cooling 
air supplied by the side plenums 166 is, through the exhaust plenums 170 
and with the aid of the shields 172, directed against and around the 
finned outer walls 120 of the mold blocks for cooling thereof. The cooling 
air leaving the exhaust 174 is preferably collected by an air exhaust hood 
(not shown) disposed above the corrugator 10. By the foregoing, the 
cooling of the mold blocks and more particularly the thermoplastic therein 
is accommodated. 
To augment the cooling along the molding section of the corrugator 10 
described above, the bottom plenum 168 provides for cooling of the mold 
blocks along the return trackway 48. In this manner any residual heat 
remaining in the mold blocks subsequent to their use in the molding of the 
tile can be dissipated. Accordingly the bottom plenum 168 has one end in 
communication with the supply duct 164, the other end of the bottom plenum 
168 disposed near the front members 54 being open. As seen in FIG. 5 the 
bottom plenum 168 communicates with and supplies cooling air to the mold 
assemblies 70 through a plurality of slots 169 directed toward the mold 
assemblies 70. To augment the cooling, upstanding walls, spaced from the 
right and left mold blocks 110 and 112, have a plurality of protruding 
diffusers 176 to assure the turbidity of the cooling air as it flows 
within the bottom plenum 168. A plurality of openings are disposed along 
the bottom plenum 168 to provide exhaust for cooling air. However, the 
space between the walls paralleling the mold blocks is the primary exhaust 
and thereby ultimately exhausts via exhaust 174. From the foregoing it can 
be seen that the mold blocks are cooled along the return trackway 52 by 
the blowing of cooling air through the bottom plenum 168. 
The aforementioned cooling of the molds is normally accomplished by the 
blowing of ambient air by the blower in the above described fashion. To 
increase the cooling effects, and thereby the speed at which the 
corrugator 10 may operate, chilled air may be used in place of ambient. 
Additionally or alternatively, water spray for evaporative cooling may be 
used along the bottom planum 168, however evaporation must be complete 
prior to the entry of the mold section by the mold assemblies 70. 
In that the continuous reception by the corrugator 10 of the heated 
thermoplastic often results in the mold blocks achieving an elevated 
equilibrium temperature, means are required to accommodate the concomitant 
thermal expansion of particularly the mold blocks. The aforementioned 
expansion, is left uncontrolled, may result in increased wear between the 
mold blocks of adjoining mold assemblies 70 as they pivotally open and 
close. Additionally, the free rolling action of the mold assemblies 70 may 
be impaired. Accordingly, the rear members 56 are interconnected to the 
frame via a pair of adjustable assemblies 177. The assemblies 177, which 
may be manually adjusted or spring loaded permit the rear members 56 to 
move right and left as shown in FIG. 1 to lengthen or shorten the endless 
trackway and more particularly the forward and return trackways 46 and 52 
thereof. To maintain the uninterrupted trackway about the corrugator 10 
the rear trackways 60 and rear surfaces 156 must be long enough to 
accommodate the adjustment of the rear members 56. 
In order to assure that the thermoplastic properly fills the molding tunnel 
136, means are required to apply a vacuum therealong particularly at the 
grooves 116. To accommodate the foregoing each of the right and left mold 
blocks 110 and 112 has, as shown in FIGS. 4, 5, 8 and 9, a plurality of 
slits 178 disposed in the grooves 116 of the corrugated inner walls 114 
thereof. Each of these slits communicates with one of a plurality of bores 
180. The bores 180 extend from the rear end face 124 of each mold block 
and have a terminus short of the forward end face 122. The bores 180 are 
in communication with semicircular grooves fashioned in the rear end faces 
124 which, when the mold blocks are closed define a continuous circular 
vacuum header 182. The vacuum header 182, in turn, is in communication 
with the top faces 130 of the mold blocks via a port 184 cooperatively 
disposed in the rear end faces 124 of each mold block. Accordingly, when 
the mold blocks are closed, the slits 178, through the bores 180 and 
vacuum header 182, are in communication with the port 184. 
To induce a vacuum within the port 184, and thereby the slits 178, a 
plurality of vacuum manifolds 186 are provided as shown in FIGS. 1 and 4. 
Each manifold 186 has a rectangular member supported above the mold blocks 
by sets of wheels 187 journalled at either end of the rectangular member. 
The wheels 187 bear against and roll along the top faces 130 of the mold 
blocks to maintain the rectangular member, and, more particularly, a 
planar sealing face 188 on the lower side thereof, in a close, parallel 
relationship with the top faces 130. In this manner clearances on the 
order of 0.002 inches (0.05 mm) may be maintained between the sealing 
faces 188 of the mainfolds 186 and the top faces 130 of the mold blocks. 
Furthermore, the use of the wheels 187 reduces the friction exerted 
against the mold assemblies 70 as they travel along the molding section. 
Accordingly it is seen that the foregoing provides a seal between the 
manifolds 186 and the stop faces 130 of the moving mold blocks. It is to 
be noted that a single manifold extending the length of the molding 
section may be used. However, the employment of separate shorter manifolds 
186, as illustrated, the combined lengths of which extends along the 
molding section, is preferred so that possible undulations in the forward 
trackway 30 can be followed by the manifolds 186 thereby maintaining the 
close clearances between the sealing faces 188 and top faces 130 noted 
above. 
To hold the manifolds 186 at their proper positions along the molding 
section, guide blocks 189 are suspended from the upper cross-members 22. 
The guide blocks 189 have a manifold slot 191 to receive and guide the up 
and down movement of the manifolds 186 as they follow the mold assemblies 
70 and more particularly the top faces 130. Each guide block 189 is also 
provided with a pin 193 which extends downwardly to register with a hole 
in the adjacent manifold 186 to restrain the manifold 186 against 
horizontal movement along the molding section. 
From the foregoing the operation of the vacuum means is evident. When the 
mold blocks close the upper and lower edges 126 and 128 thereof mate 
creating the continuous vacuum header 182 in the rear end faces 124 of the 
mold blocks. The planar forward end faces 122 of a succeeding mold 
assembly 70, as shown in FIG. 7, abuttingly engage the rear end faces 124 
sealing the header 182 from the environment along the molding section of 
the corrugator 10. In a like fashion all the headers 182 of the mold 
assemblies 70 within the molding section are sealed. As the ports 184 
communicate with the mainfolds 186 a vacuum is induced thereby in the 
headers 182, bores 180 and the slits 178. In this manner, as the 
thermoplastic is dispensed in the molding tunnel 136, the corrugations 
thereof become entirely filled since any air tapped therebetween is 
evacuated. Additionally the vacuum tends to draw the plastic into the 
grooves 116. 
To enable the corrugator 10 to be movable, the corrugator 10 has four 
wheels 190 extending outwardly from the side beams 14 to support the 
corrugator 10 upon a pair of rails 192. One of the forward wheels 190 is 
chain driven by a drive motor 194 as shown in FIG. 2. From a motor control 
center (not shown) the drive motor 194 may be operated thereby causing the 
corrugator 10 to move along the rails 192 toward a stationary extruder 196 
in preparation to the molding of tile or any therefrom for maintenance. 
From the foregoing the operation of the corrugator 10 can be set forth. 
Moving the corrugator 10 toward the extruder 196 causes the extruder head 
198, shown in FIG. 7, to be received into the molding tunnel 136. 
Typically the extruder head 198 has an annular passageway 200 through 
which heated, thermoplastic 202 is dispensed in a cylindrical fashion. An 
axial member 204 protrudes axially into the molding tunnel 136 and 
typically has a radially outwardly extending annular seals (not shown). 
Through the axial member 204 compressed air or the like may be admitted 
to, between the extruder head 198 and the annular seals, expand the 
thermoplastic against the corrugated inner wall 114 of the molding tunnel 
136. A typical extruder head 198 is described in U.S. Pat. No. 3,981,663 
issued Sept. 21, 1976 to Lupke. 
Subsequent to the positoning of the corrugator 10, the sprocket motor 114, 
blower and vacuum pump are started via appropriate controls on the motor 
control center. Thereafter, the thermoplastic 202 is dispensed from the 
extruder head 198 into the molding tunnel 136 in the fashion illustrated 
in FIG. 7. Due to the above described expansion of the thermoplastic and 
vacuum induced through the slits 178, the thermoplastic 202 mates with the 
corrugated molding tunnel 136. In that the mold assemblies 70 are 
continuously rolling along the molding section, the dispensed 
thermoplastic 202 is continuously formed into a corrugated tile 206. 
At the end of the molding section the mold blocks pivotally open radially 
from the tile 206 which has been cooled by air from the blower. To augment 
the separation of the mold blocks from the tile 206, the vacuum manifold 
186 near the end of the molding section may be supplied with a compressed 
gas. In this manner, the compressed gas flows through the slits 178 to 
blow the tile 206 away from the mold blocks. 
The mold assemblies 70 not dedicated to the formation of the molding tunnel 
136 are continuously returned along the return trackway 32 where they are 
cooled. 
If a different size tile 206 is desired, the right and left mold blocks 110 
and 112 are removed from each mold assembly 70. A pair of mold blocks 
defining a different size tile are thereafter secured to the carriages 72. 
It is to be noted that the interchanged mold blocks must have top faces 
130 which can slide along the vacuum manifolds 186 in the manner described 
above. 
While we have shown and described certain embodiments of a tile corrugator 
it is to be understood it is capable of many modifications. Changes, 
therefore, in the construction and arrangement may be made without 
departing from the scope of the device set forth above and as described in 
the attached claims.