Abstract: Compositions and methods for manufacturing containers from sheets having a hydraulically settable matrix are disclosed. Suitable compositions are prepared by mixing together a hydraulic binder, water, and appropriate additives (such as aggregates, fibers, and rheology-modifying agents) which impart predetermined properties so that a sheet formed therefrom has the desired performance criteria. Hydraulically settable sheets are formed from the mixture by extrusion, then calendering the sheets using a set of rollers and then drying the sheets in an accelerated manner to substantially harden the sheets. The resulting hydraulically settable sheets may have properties substantially similar to sheets made from presently used materials like paper, cardboard, polystyrene, or plastic. The sheets can be laminated, corrugated, coated, printed on, scored, perforated, cut, folded, rolled, spiral wound, molded, assembled and seamed to mass produce articles of manufacture from the sheets such as food and beverage containers.

Abstract: A machine for making plastic tubing including a plurality of separate carriages for carrying mold blocks about the continuous path. First and second wheel pairs on opposite sides of each carriage ride on first and second tracks respectively through a molding section of the path. An offset wheel is disposed between the wheels of each pair and rides on guide tracks associated with and facing oppositely to the first and second tracks respectively through the molding section. Each mold block is a plurality of sub-blocks secured end to end, with each sub-block having an arcuate face and corrugated with not more than one complete wavelength. Vacuum channels about sub-block end surfaces connect the block face to a vacuum port.

Abstract: A sheet of loop material adapted to be cut into pieces to form loop portions for fasteners of the type comprising releasably engageable hook and loop portions, or to be incorporated into items such as disposable garments or diapers or into sheets of abrasives. The sheet of loop material includes a sheet of longitudinally oriented fibers having anchor portions and arcuate portions projecting in one direction away from the anchor portions, and a layer of thermoplastic backing material extruded onto the anchor portions to bond to the anchor portions and form at least a portion of a backing for the loop material. The thermoplastic backing material can also bond the sheet of fibers to a sheet of backing material.

Abstract: A cross-laminate of two or more individually stretch oriented films where the directions of orientation of the films are in criss-crossing relation, has a pattern of generally parallel elongated ribs extending lengthwise of the laminate. The ribs are defined between generally transversely coincident convex and concave curved surfaces on opposite faces of the laminate, the concave surface having a radius of curvature greater than that of the convex surface so that the ribs have a thickness greater than the average thickness of the laminate. The laminate material adjacent to lateral boundaries of the ribs is in a tensionless state reversely curved relative to the rib curvature making the material between adjacent pairs of ribs generally flat. The rib pattern is preferably regular with a preferred average transverse spacing between adjacent ribs, measured peak to peak, of about 1-10 mm. The convex surfaces of the ribs can all be on the same side of the laminate or can alternate in series between opposite sides.

Abstract: The invention relates to a method and an apparatus for forming ribs with sideward projections in a plastic pipe. The projections are formed by means of elongated rolls (10) each moving around the pipe and rotating about its central axis, the rolls being in an inclined position and at an oblique angle with respect to the central axis of the pipe.

Abstract: A travelling mold has mold blocks formed by opposing mold block sections which open and close relative to one another. The mold sections travel horizontally around a continuous track which is fitted with a plurality of side-by-side mold block carriers on which the mold block sections are releasably supported. The mold block carriers are provided with carrier gears which engage with the main drive gear of the mold so that the mold is driven by engagement of the drive gear with the carriers and not the mold block sections.

Abstract: A mold apparatus has a plurality of sets of mold block parts which move to and from a product forming mold tunnel along the apparatus. Each set of mold block parts has at least one liquid receiving channel and a liquid supply is provided for supplying cooling liquid to the channel. The ends of the channel are open for feeding the cooling liquid into one end and draining the cooling liquid from the other end of the channel when the set of mold block parts is in the mold tunnel and seals are provided to prevent leakage of any cooling liquid trapped in the channel when the mold block parts are away from the mold tunnel.

Abstract: An apparatus for the manufacture of corrugated pipes of thermoplastic plastics, which has circulating mold segment halves disposed in two opposite rows subsequent to an injection head, includes a wedge element for separating the mold segment halves. This wedge element is displaceable parallel to the direction of production. Further, grab equipments are provided to be displaceable,counter to the direction of production, by which one additional mold segment half at a time can be moved to the downstream end of a molding path, removed from the latter in the direction of production and moved into a parking position.

Abstract: Sheet products having a waved marginal portion are prepared by passing a sheet of a plastic material through and compressing the sheet between shaped circumferential rollers which are positioned and configured to provide therebetween a plurality of differing nip clearance gap distances and to compress the sheet to form an intermediate sheet portion flanked by a marginal waved flanking portion and a second flanking portion, wherein the intermediate portion has a thickness greater than the second portion which, in turn, has a thickness greater than the marginal waved portion.

Abstract: An improved, endless mold tunnel, clamshell-type, thermoplastic tube molding apparatus and method using exteriorly disposed, compressive roller elements and a cooperating keyway/matching lug assembly for maintaining the alignment of the independent mold blocks and mold block half sections substantially orthogonal relative to opposed half sections and relative to the contiguous upstream and downstream mold blocks in said tunnel while allowing for the introduction of cooling fluid or vacuum.

Abstract: A machine for making plastic tubing including a plurality of separate carriages for carrying mold blocks about the continuous path. First and second wheel pairs on opposite sides of each carriage ride on first and second tracks respectively through a molding section of the path. An offset wheel is disposed between the wheels of each pair and rides on guide tracks associated with and facing oppositely to the first and second tracks respectively through the molding section. Each mold block is a plurality of sub-blocks secured end to end, with each sub-block having an arcuate face and corrugated with not more than one complete wavelength. Vacuum channels about sub-block end surfaces connect the block face to a vacuum port. Cooling water channels about sub-block end surfaces connect to water inlet and discharge ports for selectively circulating cooling water through the blocks.

Abstract: A travelling mold has mold block sections which are driven around an endless track. The mold has a drive system including a first drive component which drives the mold block sections in abutting positions with one another to a second component in the drive system which accelerates and separates the mold block sections and which then decelerates and regroups the mold block sections in their abutting positions before the mold block sections are returned to the first drive component. This separation and regrouping of the mold block sections eliminates the necessity of having a complete chain of abutting mold block sections completely around the mold.

Abstract: In a method of forming a hollow product in a molding apparatus having an upstream and a downsteam end a parison of thermoplastic material is extruded in a molten state from a heated extruder at the upstream end and moved through a product shaping region towards the downstream end of the apparatus. The material is cooled by passing a cooling medium internally of the product from the downstream end towards the upstream end of the apparatus.

Abstract: An apparatus for the production of corrugated tubing from thermoplastic synthetic resin including a shaping path following an extrusion head of an extruder and composed of a guide which is arranged in a frame and on which mold halves, fitted together in a pair at an inlet to define annular molds in a compact train as a travelling mold moving with the tube are advanced by at least one drive pinion arranged at an initial part of the shaping path, the pinion being in mesh with racks on the fitted together mold halves. At an exit point following the shaping path, the mold halves are separated from one another and are gripped by gripping arms provided with coupling devices and area shunted back to the inlet of the shaping path. The gripping arms are bearinged by drives in a movable fashion on carriages. The carriages are able to be reciprocated by drives on guides on return paths parallel to the shaping path.

Abstract: An apparatus for the manufacturing of plastic pipes has half shells of which two at a time combine as a pair to form a mold. It is provided with a temperature-regulating bell. Supply lines are formed as flexible supply hoses of temperature-resistant plastic material. A line conduit accommodating them is provided with a protecting tube, which accommodates the supply hoses and which is provided with a heat insulation towards an injection head.

Abstract: Provided is an improved corrugated containerboard that includes a corrugated medium sandwiched between and secured to a top liner and a bottom liner. The corrugated medium, top liner, and bottom liner each include fibers that are oriented in a machine direction, and the corrugated medium defines a plurality of flutes that are oriented in the machine direction. The improved corrugated containerboard is constructed from conventional paperboard which is drawn through a corrugation system in the machine direction. A first piece of paperboard is drawn between a pair of dies to form the corrugated medium with flutes oriented in the machine direction. A second and third piece of paperboard are glued to either side of the corrugated medium to form the corrugated containerboard. Each die includes an engaging surface with ridges thereon, and the engaging surfaces are opposed and define a forming zone therebetween which the first piece of paperboard is drawn through.

Abstract: An apparatus for continuously manufacturing a corrugated sheet having a varying fold width and also having fold lines extending either straight or in wavy or zig-zag fashion in a direction widthwise thereof. The apparatus includes upper and lower toothed rolls each made up of a group of toothed discs and having a circumferential groove defined between each neighboring toothed discs. At least one of the upper and lower toothed rolls is supported for adjustment in position relative to and in a direction towards and away from the other of the upper and lower toothed rolls. Upper and lower guide bars while extending in a direction parallel to the upper and lower toothed rolls are accommodated within the circumferential grooves for movement in a direction towards and away from each other over a distance corresponding to the height of each tooth of any one of the upper and lower toothed rolls.

Abstract: A machine for making plastic tubing including a plurality of separate carriages for carrying mold blocks about the continuous path. A mold train drive engages a selected number of carriages at the beginning of the mold tunnel to continuously drive the carriages along the mold tunnel. A shuttle drive follows the continuous path through a shuttle area and spaced from the path along a substantial portion of the mold tunnel, and includes first and second carriage engaging sections at substantially opposite points along the drive so that a carriage at the end of the mold tunnel becomes engaged by one shuttle drive engaging section while the other shuttle drive engaging section engages a carriage at the beginning of the mold tunnel.

Abstract: A machine for making plastic tubing including a plurality of separate carriages for carrying mold blocks about the continuous path. First and second wheel pairs on opposite sides of each carriage ride on first and second tracks respectively through a molding section of the path. An offset wheel is disposed between the wheels of each pair and rides on guide tracks associated with and facing oppositely to the first and second tracks respectively through the molding section.

Abstract: An improvement in a corrugated strip having major flat sections which extend between longitudinal edges of the strip and which are joined along lateral edges by intermediate sections extending between the major flat sections, includes stiffening ribs protruding from the strip along at least one of the connected lateral edges of the major flat and intermediate sections, the stiffening ribs being oriented substantially perpendicularly to the lateral edges. Additionally, a method and apparatus for forming corrugated strips, including corrugated strips having stiffening ribs, includes structure for applying a force, through dies, to a strip of material along an axis which is oriented at an acute angle to the strip.

Abstract: A travelling mold tunnel for the vacuum forming of profiled tube from extruded parison of molten thermoplastic material includes a plurality of parallel mold cavities with a vacuum applied to each of the mold cavities.

Abstract: Sheet products having a waved marginal portion are prepared by passing a sheet of a plastic material through and compressing the sheet between shaped circumferential rollers which are positioned and configured to provide therebetween a plurality of differing nip clearance gap distances and to compress the sheet to form an intermediate sheet portion flanked by a marginal waved flanking portion and a second flanking portion, wherein the intermediate portion has a thickness greater than the second portion which, in turn, has a thickness greater than the marginal waved portion.

Abstract: A rolling mill for use in a noodle making apparatus, of the type adapted for rolling a noodle sheet of a predetermined width, includes a plurality of rolling sections arranged in a set and each having pairs of upper and lower rolls. The set includes a pair of grooved rolls for pressingly forming a plurality of mountain and valley portions on the noodle sheet parallel to the extending longitudinal direction thereof, and at least one pair of gear-type rolls for pressingly forming a plurality of mountain and valley portions on the noodle sheet parallel to the transverse direction thereof.

Abstract: An apparatus for the manufacture of pipes having transverse profile features has a machine bed, on which half shells, which can be combined to form a mold, are rotatably and displaceably drivable. The half shells are pressed together on a molding path by guide rails, of which one is displaceable at right angles to the direction of production by hydraulically actuatable drives. Interlockings may be provided in addition, a locking member of which engaging with an associated locking recess.

Abstract: The invention concerns apparatus for molding tube (20) utilizing a travelling mold tunnel. The tunnel is made up of mold blocks (16) each comprising parts (13, 15) which are hinged together to be closeable to form the tunnel and openable to release tube from the tunnel. The opened mold blocks (16) from the downstream end of the tunnel are opened and returned to the upstream end without change in their orientation to reform the tunnel about an extrusion nozzle (18) for thermoplastic extrudate.

Abstract: An apparatus for manufacturing from a mouldable material a pipe having ribs on its outer surface and a smooth inner surface has a core including a shaft, a conically widening mandrel located downstream of the shaft in a direction of production and a kernel having an initial zone and an end zone respectively of substantially uniform diameters successively disposed downstream of the mandrel. An extrusion sleeve surrounds the core and forms with the core a nozzle for the material. The extrusion sleeve has a first end face located upstream of the kernel. Moulds encase the extrusion sleeve and the core, the moulds being movable along endless paths and having grooves on inner surfaces for forming the ribs on the pipe. A heater heats the initial zone of the kernel, the initial zone of the kernel being cylindrical. A first cooler cools the end zone of the kernel.

Abstract: A process and apparatus for rapidly and accurately forming corrugated substructures of complex shapes utilizing composite material A plurality of movable elongated ribs are positioned on a base plate for lateral movement between an open position at which all of the ribs are physically separated and a closed position at which each of the ribs is engaged with its adjacent rib or ribs. The ribs are so formed that when they collectively assume the closed position, upper regions of the ribs remain spaced apart to define longitudinally extending channels. A pre-cut sheet of composite prepreg material is laid over the ribs so as to be coextensive with them. The ribs are then moved together mechanically or by means of vacuum drawing the sheet material into the channels or both. With the aid of elongated tooling bars placed on the outer surface of the sheet material and aligned with successive channel s, the sheet material is drawn into conforming relationship with the ribs.

Abstract: A method and apparatus for manufacturing a hose for a vacuum cleaner, such hose having anti-whistling characteristics. In a standard blow molding process, a blow pipe is configured with a plurality of printing rollers having arcuate outer surfaces configured and spaced in such a manner as to assure engagement of the entirety of the hose with a printing roller during the manufacturing process. The printing rollers are provided with apertures which, upon engagement with the tacky material of the inner surface of inwardly extending corrugations causes indentations or protrusions in such surface. The roughened interior surface prevents the formation of audible harmonics when air passes through the tube in response to a vacuum source at one end thereof.

Abstract: For the continuous manufacture of a compound pipe with a pipe socket including a smooth internal tube and an external tube provided with transverse grooves and welded together with the latter, an external tube and an internal tube are extruded, the latter into the external tube. While the normal compound pipe is manufactured, gas is blown at a slight overpressure into the space beteen the external tube and the internal tube. When the pipe socket is produced, this space is vented so that a full-surface bearing of the internal tube against the external tube is achieved, to which end the internal tube is acted upon from its inside by gas under pressure.

Abstract: The device includes a toothed wheel on which pleats of a sheet 10 are preformed, in some cases with the aid of a second toothed wheel 31, and a device for holding by a vacuum; then the preformed pleats are transferred to a pleat gathering wheel 13 either directly or through the medium of a pleat pressing wheel, where they are laid down then fixed to form a pleated sheet 23. The toothed wheels 5 and 31 and the pleat pressing wheel and/or the pleat gathering wheel 13 can be arranged to produce areas with no pleats at regular intervals.

Abstract: The invention concerns an apparatus and process particularly for molding profile thermoplastic tubing and process. The apparatus includes the travelling mold type for molding profile tubing, e.g. corrugated or ribbed, including double walled tubing of various types. A sizing plug for the internal diameter of the pipe is provided with suction applying device which applies suction of diminishing strength in the upstream direction of the plug to the inside diameter of the pipe to provide a smooth inside wall of the pipe and allowing faster pipe formation. Suitably, the plug is a cooling plug and provision may be made for communicating the suction to cooling liquid to draw it to the surface of the plug to provide lubrication for a faster pipe forming process.

Abstract: Disclosed is an apparatus for longitudinally pleating a moving lamina. The apparatus features a curved axis roll having a stationary axis circumscribed by a rotating sleeve with a plurality of circumferentially oriented grooves in the rotating sleeve. The pleats are produced by the intermeshing of the lamina with the grooves of the rotating sleeve. Preferably a complementary curved axis roll having lands which interdigitate with the grooves of the first roll is used in conjunction with the first curved axis roll.The apparatus preferably further comprises a third curved axis roll disposed upstream of the first curved axis roll to substantially equalize the paths of travel of any points on the moving lamina by compensating for differences in the paths of travel between the edges and centerline of the lamina.

Abstract: An apparatus for stamping a monofilament to form shaped portions for slide fastener coupling elements, including: a stationary shaft having a mandrel extending from its one end; a pair of stamping rollers comprising a cylindrical roller and an annular roller; and a monofilament supply roller for supplying a monofilament. The apparatus stamps a monofilament so as to provide coupling head portions, leg turnover portions, deformed portions, grooves, etc. of slide fastener coupling elements.

Abstract: A corrugator for ribbing pipes includes two synchronously circulating chains of mold halves, a guide device for the mold halves having an input zone in which the associated mold halves are brought into engagement with each other, a molding zone in which a central channel is provided for guiding the engaged mold jaws and an output zone in which the mold halves are again separated from each other, as well as return guides for the mold halves on the path between the output and input zones and cooling apparatus for cooling at least the central channel with a coolant. A plurality of hollow profile modules is provided for forming the molding zone, each module being provided with a central cavity for the cooling apparatus and two lateral guide portions. Modules are arranged in pairs joining each other transversely of the production direction of the corrugator, and a plurality of module pairs are arranged adjoining each other in series in the production direction of the corrugator.

Abstract: A pleating machine for dual fluted shades consisting of a pair of cooperating sets of pleating conveyors closely adjacent and flanking a sealing device that joins the two resulting pleated webs together by transversely fed attaching sheets.

Abstract: Pipes with special profile sections are produced by an apparatus with circuit guided half shells. The half shells combining to form a mold have mold walls extending about parallel to a mold space axis. Vacuum slits extend about parallel to the mold space axis to open into a mold space in each case at a place radially the most distant from the mold space axis.

Abstract: The invention relates to a method and apparatus for manufacturing ribbed piping, wherein a formable mass in a plastic state is extruded into a substantially cylindrical forming space of a corrugator, the forming space being delimited by forming molds movable in the production direction of the apparatus and having grooves on the inner surface thereof for forming rib flanges. A stationary kernel portion of a mandrel cools the interior surface of the piping and extends beyond the forming space constituted by the forming molds of the corrugator.

Abstract: An improved system for fabricating convolutely wound tubes includes a supply roll support for supporting a large supply of paperboard, an adhesive applicator for receiving paperboard from the supply roll and applying a coating of adhesive to one side thereof, a cutting station for cutting the paperboard across its length to form sheets of paperboard, and a winding station including a mandrel about which cut sheets of adhesive bearing paperboard are wound into a tubular configuration. As the paperboard is drawn from the supply roll, one of its edges passes sequentially through three corrugating nip rolls, which alternately deform the material of the edge to render it more pliable and flexible. This flexible edge, then, becomes the trailing edge of paperboard sheets that are wound into tubes such that the edge can be easily conformed to the contour of and adhered to the outer surface of the finished tube.

Abstract: A process and apparatus for the manufacture of a pleated filter insert made of a thermoplastic material. The pleat walls are maintained at a distance with the filter pleats open in the direction of outflow of the filter insert by elongated ribs made of the filter material itself. The tape-like filter material is gathered in a first process step. The elongated ribs are produced by means of tension-free, permanent shaping of the gathered filter material, heated to a temperature which is below the shrinking temperature and above the deformation temperature of the filter material, between the jaws of a shaping device. The intermediate areas of the filter material intended for the forming of pleat wall edges are heated by at least one heater jaw to a temperature which is between the deformation temperature and the melting temperature until the irregularities of the filter material in the intermediate area have been smoothed out.

Abstract: The invention concerns apparatus for making corrugated tubing. Mold blocks for formation of a travelling mold tunnel are provided with suction to the mold face by means of communication between suction passages in the mold block and a suction chamber. Each mold block has a channel which slidingly engages a track of the suction chamber to receive suction as the mold blocks travel over the track. Tongue and groove connectors are provided between the channel of each block and the track of the suction chamber and communication surfaces of the tongue and groove connectors to provide suction from the suction chamber to the mold face.

Abstract: A method and apparatus for producing a pipe transports first and second sets of chill moulds respectively along first and second endless paths, the chill moulds of each set being so transported one after another, and the endless paths being positioned such that junction faces of the respective chill moulds of the respective sets are positioned against each other in a pipe moulding zone of the endless paths. So positioning the respective chill moulds of the respective sets also defines outer surfaces thereof that are opposite the junction faces and outer surfaces that extend along edges of the junction faces at least generally in the direction of the transporting of the chill moulds.

Abstract: A machine and process for a web of material employing two side-by-side sets of spaced apart driven disks adapted to rotate respectively in opposite directions about two spaced apart parallel axes, the axes being sufficiently close that peripheral margins of the disks of one set run between the peripheral margins of the disks of the other set in a mated relationship, the sets of disks mutually defining a series of web driving regions spaced apart in a direction parallel with the axes, with successive web driving regions, offset from one another, open channels between said disks providing, with the driving regions, a width-wise continuous, non-linear cross-section corridor through which the web passes, the driving regions adapted to impart to a web led lengthwise into the corridor, crosswise tension in the web, pulling the web about the edges of the disks, the tension enabling the disks to apply forward driving force to the web and retarding means closely disposed to the driving regions located to apply retardi

Abstract: Apparatus for forming elongate laminate into a predetermined configuration having a substantially uniform cross-sectional shape in the axial direction, including a plurality of roller pairs having complementary transverse peripheral profiles, plate members disposed between the roller pairs and the laminate and having a transverse configuration corresponding to the peripheral profiles of the rollers.

Abstract: A pleating machine with two engaging pleat forming chain conveyors, one with forming rollers and the other with forming plates both directly mounted on special links in the chains.

Abstract: An apparatus for corrugating a flexible web containing heat softenable fibers comprising two pairs of endless drive chains with paddles mounted to each pair of chains to extend radially outward therefrom. The web is introduced onto the paddles at a point where the paddles are fanned out by passage of the paddles about the arcuate end of the endless chains. The web is folded between the paddles as the separation between the paddles is closed when the paddles move from the arcuate to the straight portion of the endless chains. Heating means soften and bond fibers of adjacent folds of the web together prior to removal of the corrugated web from the paddles.

Abstract: A method of forming a hole in a plastic pipe feeds a plastic layer for the plastic pipe from a nozzle about a mandrel into chill moulds being displaced along an elongated mould cavity about the mandrel formed by the chill moulds. All of the plastic layer is pressed into the chill moulds with a pressure medium between the mandrel and all of an inner surface of the plastic layer for forming the plastic pipe therefrom. Only portions of the plastic layer of the plastic pipe are then subjected to a local pressure difference exceeding the breaking limit of the plastic layer between the inner surface and an opposite, outer surface of the plastic layer at least in part from a flowing medium for forming a hole in the plastic layer of the plastic pipe, the flowing medium being one of a gas and a liquid and flowing from the mandrel at a pressure higher than that of the pressure medium pressing the plastic layer of the plastic pipe.

Abstract: A machine and method for longitudinally compressing a web under the influence of driving forces provided at a nip line defined by spaced-apart pairs of matched rotating disks and under the influence of retarding forces provided by sets of retarding fingers inserted in the spaces between the disks.

Abstract: An apparatus for the passivating, multistage compaction of hot iron particles supplied in the form of a packed bed from a reduction unit and for the subsequent breaking apart of the compacted iron band is described. Prior to the final compacting, the iron particles pass through a homogenizing and precompressing stage. Thus, the compacted iron has a pore volume of max. 40% and a density of at least 5.5 g/cm.sup.3. The iron compacted to a band is subsequently guided between the rollers (7,8,11) of a separating stage exposing it to bending stresses such that it breaks apart at the predetermined desired breaking points. The breaking points have a smaller density than the band regions between them. They can be produced in that in the precompression stage the feed speed is briefly decelerated compared with the feed speed in the compaction stage or in the compaction stage there is less marked compression at these points than in the intermediate regions.

Abstract: A corrugator for molding externally ribbed and corrugated thermoplastic pipes, including two trains of moldblock halves circulating respectively in two endless paths and cooperating with each other to form a travelling mold for the thermoplastic pipes. The halves of one train are biased in relation to and overlap those of the second train along the travelling mold and are provided with intermeshing elements hooking the halves of the two trains together.

Abstract: A corrugated mold block for a vacuum mold machine is provided with a face arcuate about a longitudinal axis and corrugated in the longitudinal direction with alternating grooves and lands, said face being formed of sheet metal. A housing is provided about the back of the face and adapted for carriage about an endless path, and reinforcing members are provided which are secured to the face and housing and extend therebetween to maintain the desired shape of the face. Openings extend through the grooves of the face to the back thereof and communicate with vacuum passageways formed by a plurality of arcuate channel members secured to the back of each of the face grooves and communicating with a vacuum port through the housing. The housing further defines a cooling passage therethrough in communication with input and output cooling ports through the housing.