CA1181564A - Plastic tile corrugator - Google Patents

Abstract

Abstract 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 track-way 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.

Description

PLASTIC TILE CORRU(;ATOR

BACKGROUND OF THE INVENTION
1. ~echnical Field This invention relates to machines which transfoxm extruded thermoplastic into a corrugated plastic tile and more particularly to machines which can continuously form corrugated plastic tiles.
This invention is a division of Canadian Patent Application Serial No. 405,022, filed June 11, 1982.
1~ 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. Patent No. 3,981,663 issued September 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 re~uire large areas of dedicated space. One of the primary factors contributing to the size of the machine is the requirement that the mold ~locks 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 fric-tion between the mold blocks, their interconnecting chains and the frame, must be of substantial horsepower to drive the mold assemblies.

Accordingly, the present invention seeks to overcome the drawbacks of corrugators heretofore used partlcularly those drawbacks set forth above.

SUMMARY OF THE INVENTION
Disclosed is a tile corrugator having a plurality of independent, rolling, mold assemblies each of which is composed of pivota]ly 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 a 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 ~hich 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.
The invention to which the claims of this divisional application are directed pertains in one aspect to a device ~:L~

for molding corrugated plastic tile of the type having an endless trackway with a pair of mold blocks continuous~y recirculating about the trackway and cooperating along a portion of the trackway to define a segment of a tunnel having a corruaated wall for receiving plastic to mold a tile. The device includes a pair of block bodies which together form the tunnel segment and have a plurality of radially and axially spaced slits about the circumference of the tunnel segment and communicates with the tunnel. The slits intersected by a plurality of circumferentially spaced bores extend in the direction of the tunnel, the bodies also having an annular opening around the tunnel and communicating with the bores and a vacuum port opening the annular opening to the outside of the blocks so that a vacuum through the port induces a substantially uniform vacuum around the tunnel through all of the slits.

The invention herein also comprehends a device for molding corrugated plastic tile of the type having an endless trackway with mold blocXs continuously recirculating about the trackway to define a segment of a molding tunnel having a corrugated wall along an axial portion of the trackway for receiving plastic to mold a tile. The device includes mold block pairs having a plurality of axially spaced slits communicating with the tunnel, the slits intersected by a plurality of circumferentially spaced bores extending into the mold blocks from one end face thereof. The one end face has a groove intersecting the bores and extends to the periphery of the one end face, the groove defining a closed passageway when the one end face of the pair of mold blocks is contiguous to another end face of an adjacent mold block pair. Means are provided for inducing a vacuum in the passageway along the trackway portion, the passageway vacuum withdrawing air ~rom the tunnel through all of the slits and bores so that the plastic conforms to the corrugated wall of the tunnel.

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Further aspectsand advan~ages of -the presen~
invention will become apparent upon a reading of the speci-fication, drawings and attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side view of an embodiment of the tile corrugator of this invention with some parts removed for clarity;
Fig. 2 is a top view of an embodiment of the tile corrugator of the present invention with parts removed for clarity;
Fig. 3 is a front view of an embodiment of the tile corrugator of the present invention with parts removed for clarity;
Fig. 4 is an enlarged partial section view of an embodiment of the tile corrugator of the present invention illustrating a mold assembly thereof;
Fig. 5 is an enlarged partial section view of an embodiment of the tile corrugator of the present invention illustrating the mold assembly in the open position;
Fig. 6 is a top view of the mold assembly carriage of the present invention;

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Fig. 7 is a view of an embodiment of the present invention illustrating the extrusion of plastic into the tile corrugator;
Fig. 8 is a side view of a mold block of the present invention with portions thereof removed for clarity;
and ~ ig. 9 is a rear end view of the mold block of Fig. 8.

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 pu,poses 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 here-inafter 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 ~rom 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 mèmbers 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 semicirular 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 wi-th the forward and return trackways 4~ and 52 to provide a continuolls 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 track-ways 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 trac~ways thereby enabling the mold assemblies 70 and more particularly their carriages 72 to roll therealong.

To maintain the mold assemblies 70 in mutual align-ment and to assure that their carriages 72 properly roll within ~he trackways, a guide 82 is positioned upon ~he 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 afore-mentioned 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 95 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 cooperati.on 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 ~orward 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 under-stood that by disposing thc 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 relation-ship is maintained as the continuous supply of ~lold 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 Eig. 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 dis-posed 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 ~ollowers 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 12G 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. 13.
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 des-cribed 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 ~oregoing 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 ~hermoplastic, as received, is at some elevated temperature, depending upon the plastic used in order to make the thermoplastic pliable and thereby sus-ceptible 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 15 in Figs. 3 and 4 each of the side plenums 166 communicates with and supplies cooling air through exhaust plenums 170 extending along the moldlng 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 thc side plenums 166 is, through the 25 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 fore--~4-going, the cooling of the mold blocks and more particularly the thermoplastic therein is accommodated.
To augmen-t 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 5~ being open. As seen in Fig. 5 the bottom plenum 168 communicates with and supplies cooling air to the mold assemblies 70 through a plur~lity of slots 169 directed toward the mold assemblies 70. To augment the cooling,upstanding 15 walls, spaced from the right and left mold blocks 110 and 112, have a plurali~y 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 plenum 168, however eva~oration must be complete prior to the entry of the mold section by the mold assemblies 70.
In that the continuous reception by the corruqatcr 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 if left uncontrollea, 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 ~0 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 ~6 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 me~bers 56.
In order to assure that the thermoplas-tic properly ~ills the molding tunnel 136, means are required to apply a vacuum therealong particularly at the grooves 116. To accommodate the fore~oing each of the right and left mold blocks 110 ~nd 112 has, as shown in Figs. 4, 5, 8 and 9, a plurality of slits 178 disposed in the grooves lL6 of the corrugated inner walls 11~ thereof. Each of these slits communicates wi-~h 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 ~. 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 ~O.GSmm) may be maintained between the sealing faces 188 of the manifolds 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 ~ingle manifold extending the length o the molding section may be used. However, the employment of separate shorter manifolds 186, as illustrated, the combined lengths of which extend 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 12~ 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 12~ 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 manifolds 186 a vacuum is induced thereby in the headers 182, bores 180 and the slits 178. In this manner, as the themoplastic is dispensed in the molding tunnel 136, the corrugations thereof become entirely filled since any air trapped therebetween is evacuated.
Additionally the vacuum tends to draw the plastic into the grooves 116.
To enable the corrugator 10 to be mcvable, the corrugator 10 has four wheels l9Q 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 19~ 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 away therefrom for maintenance.
From the foregoing the operation of the corrugator 10 can be set forth. Moving the corrugator lQ toward the extruder 196 causes the extruder head 19~, 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 2Q4 compressed air or the like may be admitted to, between the extruder head 198 and the annular seals, expand the thermo-plastic against the corrugated inner wall 114 of the molding ~unnel 136. A typical extruder head 198 is described in U~S.
Patent No. 3,981,663 issued September 21, 1976 to Lupke.
Subsequent to the positioning of the corrugator 10, the sprocket motor 114, blower and vacuum pump are started via appropriate controls on the motor control center. There-after, 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 the 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 tlle 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 rlows 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 moldincJ tunnel 136 are continuously returned along the return trackway 32 where they are cooled.

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If a different size tile 206 is desired, the right and left mold blocks 110 and 112 are removed from each mold assembly 70. ~ 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 1~6 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 o.E
many modifications. Changes, therefore, in the construc~ion and arrangement may be made without departing from the scope of the device set forth above and as described in the attached claims.

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a device for molding corrugated plastic tile of the type having an endless trackway with mold blocks continuously recirculating about said trackway to define a segment of a molding tunnel having a corrugated wall along an axial portion of said trackway for receiving plastic to mold a tile, the improvement comprising:
mold block pairs having a plurality of axially spaced slits communicating with said tunnel, said slits intersected by a plurality of circumferentially spaced bores extending into said mold blocks from one end face thereof, said one end face having a groove intersecting said bores and extending to the periphery of said one end face, said groove defining a closed passageway when said one end face of said pair of mold blocks is contiguous to another end face of an adjacent mold block pair; and means for inducing a vacuum in said passageway along said trackway portion, the passageway vacuum withdrawing air from said tunnel through all of said slits and bores so that said plastic conforms to the corrugated wall of said tunnel.

2. The device of claim 1, wherein said one and another pairs of mold blocks abut along said portion, said one end face mating with said another end face to cover said groove and define said closed passageway.

3. The device of claim 2, wherein said vacuum means is a vacuum header disposed to communicate with said passageway along said trackway portion.

4. The device of claim 1, wherein said corrugated wall is defined by alternating grooves and lands and said slits are disposed in said grooves.

5. The device of claim 1, wherein said mold block pairs have arcuate cuts defining said slits.

6. In a device for molding corrugated plastic tile of the type having an endless trackway, a pair of mold blocks continuously recirculating about said track-way and cooperating along a portion of said trackway to define a segment of a tunnel having a corrugated wall for receiving plastic to mold a tile, comprising:
a pair of block bodies which together form said tunnel segment and having a plurality of radially and axially spaced slits about the circumference of the tunnel segment and communicating with said tunnel, said slits intersected by a plurality of circumferentially spaced bores extending in the direction of said tunnel, said bodies also having an annular opening around said tunnel and communicating with said bores and a vacuum port opening said annular opening to the outside of said blocks so that a vacuum through said port induces a substantially uniform vacuum around said tunnel through all of said slits.

7. The mold blocks of Claim 6, wherein said pair of block bodies include at least three uniform spaced bores.

8. The corrugator of Claim 1, wherein said slits and bores are circumferentially located to provide a substantially uniform vacuum about the circumference of the tunnel.

9. The corrugator of Claim 1, wherein said slits are substantially uniformly spaced about the tunnel circumference.

10. The corrugator of Claim 1, wherein each mold block pair includes at least three uniformly spaced bores.