Abstract:
A rotary cutter separates a molten plastic pellet from a nozzle and deposits the molten plastic pellet into a mold of a mold cavity. The cutter blade includes a cutter blade and a cutter shaft rotatable about an axis of the shaft. The cutter blade is mounted to extend radially from an end of the shaft, the shaft positionable adjacent the nozzle such that the rotary path of the cutter blade closely conforms to a facing surface of the nozzle. An air conduit extends through the cutter shaft to the cutter blade. An air orifice in communication with the air conduit is oriented to direct a stream of air radially along the cutter blade to displace a molten plastic pellet from the cutter blade with a stream of pressurized air. The delivery of pressurized air is precisely timed to displace the pellet from the cutter blade and into the mold cavity.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to a method and apparatus for cutting discrete quantities of molten plastic material from a supply of the molten plastic material for subsequent compression molding of the discrete quantities of material. More particularly, the invention relates to a cutter which rotates relative to a molten plastic delivery nozzle to cut a pellet of molten plastic from the nozzle and then carries and ejects the pellet of molten plastic into a cavity for compression molding articles therefrom. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,277,431, to Peller, hereby incorporated by reference, discloses an apparatus for cutting discrete quantities or pellets of molten plastic material for subsequent placement in respective mold cavities. This apparatus is particularly suited for use in the manufacture of closures by compression molding, including the formation of compression molded closure shells, and the formation of compression molded liners within associated closure shells. U.S. Pat. Nos. 4,343,754 to Wilde et al., and 4,497,765 to Wilde et al., both hereby incorporated by reference, disclose compression molding of threaded, tamper-indicating plastic closures, and compression molding of liners in such closures, for which manufacturing processes the apparatus of the above U.S. Pat. No. 4,277,431 is suited for use. 
     The apparatus of U.S. Pat. No. 4,277,431 includes a nozzle through which molten plastic material is delivered from an associated extruder or the like, and a rotatably driven cutting blade which is rotated with respect to the nozzle. As plastic is extruded from the nozzle, a discrete quantity or pellet of plastic material is cut during each rotation of the associated cutting blade. Immediately thereafter, the severed plastic pellet is moved from the face of the nozzle by the cutting blade for delivery to a respective mold cavity. The mold cavity may comprise either a female mold die for formation of a closure shell by compression molding, or a closure shell within which the molten plastic is compression molded for formation of a sealing liner. 
     Notably, the cutter apparatus of the above patent is configured to facilitate separation of each plastic pellet from the cutting blade by creating a slight mechanical interference between the cutting blade and the face of the associated nozzle. Thus, as the cutting blade rotates with respect to the nozzle, the blade is flexed or deflected as it engages the nozzle face and severs the extruded plastic material. As the blade continues to rotate, with the severed plastic material carried on the flexed surface of the cutting blade, the cutting blade disengages the face of the nozzle, thereby rapidly accelerating the pellet to facilitate its separation from the blade and delivery of the pellet to one of the associated cavities. This cutting and subsequent “flicking” like action of the cutting blade is sometimes referred to as the “cut-and-flip” portion of each cutting cycle. 
     The above patent contemplates that the disclosed cutting apparatus be mechanically-driven from the associated molding apparatus, thus effecting the desired synchronous operation of the cutter. However, it will be appreciated that increases or decreases in production speed necessarily result in corresponding variation in the “cut-and-flip” portion of the cutting cycle, which can create undesirable variability in the speed, direction, rotational velocity, and orientation of the plastic pellet as it is delivered to the associated cavity. This can, in turn, create problems regarding pellet placement, orientation, and an undesirable tendency of the pellet to bounce upon delivery into the associated cavity. 
     U.S. Pat. No. 5,596,251 describes a cutter apparatus driven by a servo motor, the operation of which is coordinated with an associated rotary carousel on which cavities are successively presented to the cutter apparatus. In order to effect separation of each discrete quantity of plastic material from the cutting blade of the cutter apparatus, the servo motor is operated to create a period of distinct deceleration during each rotary cutting cycle, thereby separating the molten plastic from the surface of the cutting blade. 
     The present inventors have recognized that it would be desirable to provide a cutter apparatus for cutting molten plastic pellets from a source of molten plastic material and placing the pellets into successive cavities for compression molding which could be effectively operated at a high rate of speed, which reduces the need to replace worn cutter blades, and which reliably operates to produce a high rate of flawlessly molded articles. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a plastic pellet cutting system particularly suited for use in compression molding of plastic closure shells, and plastic liners in closure shells. The present invention contemplates a rotating cutting blade operated in conjunction with a molten plastic delivery nozzle to separate plastic pellets from a face of the nozzle. The present system utilizes a cutting blade operated at zero interference (or with slight clearance) with the associated nozzle face, wherein the cutting blade has associated therewith an air driven pellet ejection system. The ejection system uses pressurized air to displace a pellet carried by the blade into a molding cavity. 
     The present system avoids the need to create mechanical interference between a cutting blade and an associated nozzle face to facilitate separation of each molten plastic pellet from the cutting blade. 
     In one embodiment, the cutting blade has associated therewith an air activated plunger which reciprocates radially in close proximity to the cutting blade to push a pellet from the blade. The plunger can be assisted by a high velocity stream of air directed at the pellet held on the cutting blade to dislodge the pellet from the cutting blade to deliver the pellet into the molding cavity. 
     In another embodiment, no plunger is used. The cutting blade has associated therewith an air delivery system which directs a high velocity stream of air at the pellet held on the cutting blade to dislodge the pellet from the cutting blade to deliver the pellet into a molding cavity. 
     The present system is used in conjunction with a rotary compression molding apparatus, which typically includes a rotating carousel or turret which carries cavities in the form of mold dies or closure shells. The present system effects delivery of discrete quantities of molten plastic material (i.e., plastic pellets) to the series of moving cavities by the provision of an extruder or like apparatus which provides a source of molten plastic material to a nozzle. A cutting blade is driven with respect to the nozzle so that attendant to each rotation of the blade, the blade cuts a discrete quantity or pellet of plastic material as it is being extruded. 
     The delivery of each molten plastic pellet is effected without significant flexure of the cutting blade, thus obviating the need for mechanical interference between the cutting blade and the nozzle face, as in arrangements heretofore known. 
     The present invention contemplates a two-piece cutter assembly mounted on a cutter shaft, the cutter shaft being rotated about its axis by a motor. The two-piece cutter assembly comprises a cutter body which is held substantially within a radial bore formed in a distal end portion of the cutter shaft, and a protruding cutter head extending from the cutter body. The cutter shaft includes an internal air passage for pressurized air delivery to the cutter body, and internal cooling channels for passing cooling fluid, such as cooling water, to and from the cutter body for maintaining the cutter body at a desired temperature during operation. The cutter assembly includes a series of air apertures directed toward an internal region of the cutter head for passing pressurized air into the cutter head to dislodge a plastic pellet held thereby, during operation. The air apertures are in flow communication with the internal air passage within the cutter shaft. The air apertures can be located on a plate stationary to the cutter body or on a reciprocating plunger. The internal cooling channels through the cutter shaft are in flow communication with an arcuate area between the cutter body and an inside wall of the radial bore within the cutter shaft. 
     The cutter shaft is rotated within a rotary union block. The cutter shaft includes a first arcuate channel around its circumference which is in flow communication with the internal air passage. The cutter shaft also includes second and third arcuate channels around its circumference which are in flow communication with the two internal cooling channels, respectively. The rotary union block includes corresponding channels or passages in flow communication with the first, second and third arcuate channels of the cutter shaft, such that pressurized air and cooling water can be sealingly transferred between the rotary union block and the cutter shaft given that the cutter shaft is rotating and the union block is stationary. A precision servo motor drives the cutter shaft via a timing belt and sprocket arrangement. 
     In operation, the cutter shaft is rotated such that the cutter head sweeps across the nozzle face to cut and carry a molten plastic pellet. At a preselected position in the rotary travel of the cutter head, a stream of pressurized air acts against the plastic pellet either directly and/or via a plunger to dislodge the pellet from the cutter head and into a compression molding cavity. 
     The preselected rotary position of the cutter head can be defined by the location and circumferential extent of air channels or passages in the rotary union block. Alternatively, the timing of the air delivery of pressurized air into the cutter head can be controlled by a programmable logic controller (PLC). 
     The invention provides advantages over the prior apparatus. The invention will reduce the probability of broken cutter blades due to fatigue and interference with the nozzle face. The invention will provide more consistent and accurate pellet placement in the compression mold. It is contemplated that the invention will reduce (stringing) of molten plastic during operation, and also decrease a pellet weight standard deviation. It is contemplated that the invention will result in reduced cutter and nozzle face wear and reduced maintenance requirements. Setup time for the apparatus should be decreased and apparatus reliability increased. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a cutter apparatus associated with a nozzle which provides a source of molten plastic material; 
     FIG. 2 is a fragmentary enlarged perspective view of a portion of the apparatus shown in FIG. 1; 
     FIG. 3 is a fragmentary sectional view taken generally along line  3 — 3  from FIG. 1; 
     FIG. 4 is an exploded perspective view of the apparatus shown in FIG. 2; 
     FIG. 5 is an exploded perspective view of an alternate cutter shaft and cutter assembly; 
     FIG. 6 is a sectional view taken generally along line  6 — 6  of FIG. 5; 
     FIG. 7 is a fragmentary enlarged sectional view taken from FIG. 6; 
     FIG. 8 is an exploded elevational view of the apparatus shown in FIG. 5; 
     FIG. 9 is an enlarged perspective view of a portion of the apparatus shown in FIG. 8; 
     FIG. 10 is a front view of the portion shown in FIG. 9; 
     FIG. 11 is a sectional view of an alternate cutter shaft carrying plural cutter assemblies; and 
     FIG. 12 is a schematic diagram of one embodiment of the operational controls of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     FIG. 1 illustrates a cutter apparatus  20  associated with a molten plastic delivery apparatus  24  and a molding carousel apparatus  28 . A precision servo motor  30  is mounted via a bracket  34  to a rotary union block  36  and to an air manifold block  38 . A cutter shaft  40  axially penetrates the rotary union block  36 , extending from a base end  42  located behind the bracket  34  to a distal end  43 . A cutter assembly  41  is located adjacent to the distal end  43 . 
     The carousel apparatus  28  is shown in fragmentary fashion. The carousel apparatus  28  includes an annular support  29  which carries a plurality of molding cavities  31  arranged in a circle. The carousel apparatus  28  is rotated in the direction R about a vertical centerline thereof. The cavities could be, for example, molding dies for forming bottle caps or shells, or bottle caps or shells for forming liners therein. 
     In operation, the rotating cutter assembly  41  cuts plastic pellets from a nozzle  60  of the molten plastic delivery apparatus  24 , and deposits the pellets into successive cavities  31  carried on the rotating carousel apparatus  28 . The pellets can then be compression molded within the cavities and thereafter removed as finished articles. 
     As illustrated in FIG. 2 the molten plastic delivery nozzle  60  faces the cutter assembly  41  and provides a nozzle face  62  having an arcuate surface for closely conforming to a circular path of an extremity  63  of a cutter blade  74 . A relative position adjustment block  70  is used to set the precise and exact relative position between the nozzle  60  and the cutter blade  74 . The adjustment block  70  includes micrometer-like adjustment knobs  76 , for precisely setting the spacing of, or clearance between, the nozzle  60  with respect to the moving cutter blade  74 . 
     As shown in FIG. 3, a driven pulley  144  is locked to the base end  42  of the cutter shaft  40  by a recessed set screw  146 . The precision servo motor  30  includes an output shaft  150  upon which is locked a drive pulley  152 . A belt  154  wraps around the drive pulley  152  and the driven pulley  144  to cause conjoint rotation of the pulleys  152 ,  144 . The belt  154  and the pulleys  144 ,  152  can be toothed for precise, no-slip rotation of the pulleys. 
     FIG. 3 illustrates the cutter shaft  40  being rotatably supported within the rotary union block  36  by front and rear bearings  180 ,  182  respectively. Arranged between an inside surface of the rotary union block  36  and the shaft  40  are a first arcuate channel  184 , a second arcuate channel  185 , and a third arcuate channel  186 , and a fourth arcuate channel  187  arranged alternatively between O-ring seals  188 . 
     The cutter shaft  40  includes arcuate and axial channels for transferring air and cooling fluid between the union block  36  and the cutter assembly  41 . The layout of those channels is more completely described below with regard to the embodiment described in FIGS. 6 through 8. 
     An axial, internal air passage  192  within the shaft  40  is in flow communication with the cutter assembly  41  and the second arcuate channel  185 . An axial cooling fluid channel  194  within the cutter shaft is in flow communication with the cutter assembly  41  and the first arcuate channel  184  via an arcuate channel  194   a  and a radial channel  194   b  in the shaft, as shown in FIG. 8. A second axial cooling fluid channel  196  within the shaft  40  is in flow communication with the cutter assembly  41  and the third arcuate channel  186  via an arcuate channel  196   a  and a radial channel  196   b  in the shaft, as shown in FIG.  8 . The arcuate channels  184 ,  186  are preferably annular. The axial channels  194 ,  196  are used to transport cooling water to and from the cutter assembly  41  to maintain the cutter temperature at a preselected temperature to keep the molten plastic in an acceptable molten state during operation. 
     A first vertical channel  186   a  extends from the arcuate channel  186 , through the rotary union block  36 , and flow connects to an L-shaped channel  186   b  through the manifold block  38 , which channel  186   b  terminates in a tube connection port  186   c . The other arcuate channels  184 ,  185 ,  187  are routed to tube connections at the manifold block, adjacent the connection  186   c , in the same or similar fashion (not shown). 
     According to the embodiment of FIG. 3, a cutter body portion  204  is sealed to the inside surface of a radial bore  224  in the shaft  40  by a plurality of O-rings  225 . A plunger  248  is reciprocably held within the body portion  204 . The cutter blade  74  is formed with the body portion  204 . The plunger  248  includes a plurality (three shown) of packing rings  254  spaced apart along an axial length of the plunger  248 . The cutter blade  74  has a semicircular cross section sized to receive a cylindrical extending portion  249  of the plunger  248 , when the plunger is extended. The extending portion  249  has a circular perforated end face  251  having perforations  252 . 
     The body portion  204  includes a plurality of openings  260  which permit air to be communicated between an inside of the body portion  204  and the radial bore  224 . When compressed air is introduced into the axial channel  192 , into the radial bore  224 , through the openings  260 , and into the body portion  204 , the plunger  248  is driven by air pressure to its extended position. The end face  251  pushes a plastic pellet from the blade  74 . Air flowing through the perforations  252  in the end face  251  also assists in ejecting the plastic pellet. 
     To retract the plunger, in a direction downwardly according to FIG. 3, the axial channel  192  can be vented through the corresponding channels of the rotary union and the manifold block while pressurized air is delivered to an elevated position between the plunger and the body portion to drive the plunger downwardly. To this end, the fourth arcuate channel  187  is provided between an inside surface of the rotary union block  36 , which channel  187  is flow connected to a source of pressurized air through the manifold block  38 . The arcuate channel  187  is open to an arcuate channel  197   a  formed on the shaft  40 , shown in FIG.  8 . The arcuate channel  197   a  is open to a radial channel  197   b  which is open to an axial channel  197  within the shaft  40 . The axial channel  197  is open to an annular space  198  located between an inwardly directed radial flange  199   a  of the body portion  204  and an outwardly directed radial flange  199   b  of the plunger  248 . Air pressure injected into this annular space acts to drive the plunger downwardly. 
     The circumferential extent, i.e. whether the arcuate channel is completely annular over 360 degrees or exists only over a portion of the 360 degrees, and the relative angular location of the arcuate channels  187 ,  197   a  and the arcuate channels  185 ,  192   a  can be designed to apply synchronized pressurization to upper and lower portions of the plunger to vertically reciprocate the plunger to eject a pellet and then be retracted for the blade to receive the next pellet. Alternatively, the arcuate channels  187 ,  197   a  and  185 ,  192   a  are completely annular over 360 degrees of the shaft outside surface and the rotary union inside surface and a controller can be used to synchronize the injection of pressurized air into, or the venting of air from, the manifold block ports corresponding to the two channels  185 ,  187  of the rotary union. 
     Alternatively, rather than applying air into the channel  198 , a vacuum can be applied via the air conduit  192  to draw the extending portion  249  of the plunger back into the body portion  204 . As a further alternative, a return spring could be placed between the body portion and the plunger to retract the plunger. 
     The cutter assembly  41  is held to the shaft  40  by use of a hold down plate  287  which is fastened by a cap screw  289  to the shaft  40 . The hold down plate clamps a shoulder of the body portion  204  to the shaft  40 . Also, the plunger  248  is guided for reciprocating movement by a central plug member  265  which is fixed in position by a bolt  266 . The bolt  266  penetrates a hole in the shaft  40  and is threadedly engaged into a threaded bore of the plug member  265 . 
     FIG. 4 illustrates the cutter apparatus  20  and the molten plastic delivery apparatus  24  in exploded view. The molten plastic delivery apparatus  24  includes a nozzle block  300  which receives molten plastic into an inlet (not shown) and dispenses the molten plastic through a central aperture  302  of the nozzle  60 . Adjustment of the position of the nozzle face  62  with respect to the cutter blade  74  is accomplished by turning the adjustment knob  76 . Horizontal adjustment wedges  306 ,  307  slide vertically relative to each other, to finely adjust the horizontal clearance between the nozzle face  62  and the cutter blade  74 . 
     FIGS. 5 through 8 illustrate the cutter shaft  40  having a back end portion  310  adjacent to the base end  42  with a keyway  312  for excepting the set screw  146  for locking the shaft  40  to the driven pulley  144 . The cutter shaft  40  includes an intermediate diameter section  316  having the plurality of arcuate channels  192   a ,  194   a ,  196   a ,  197   a  which flow connect, via short radial passages  192   b ,  194   b ,  196   b ,  197   b , the axial channels  192 ,  194 ,  196 ,  197  with the channels or passages  184 ,  185 ,  186 ,  187  respectively within the rotary union block  36  (also see FIGS.  6  and  8 ). The channels  197 ,  197   a ,  197   b ,  187  are not used in the embodiment of FIGS. 5 through 11 but are used in the embodiment of FIGS. 1 through 4. 
     On a front side of the intermediate diameter section  316  is a large diameter section  320 , larger in diameter than the intermediate diameter section  316 . Within the large diameter section  320  the radial bore  224  extends perpendicularly to the axis of the shaft  40 . An alternate cutter assembly  341  is partly held within the radial bore  224 . The cutter assembly  341  includes a tubular body portion  350 . The tubular body portion  350  has three circumferential grooves  362 ,  364 ,  366  for holding three O-rings  370 ,  372 ,  376  respectively. The body portion  350  includes on a distal end thereof a perforated plate  380  having a plurality of air orifices  382 . A substantially semicircular frame  396  extends upwardly from the perforated plate  380  and includes a flange portion  398  having connection holes therein. An end bumper  404  is arranged below the body portion  350 . The end bumper  404  is in the form of a solid circular plate. 
     A cutter head  470  includes a semicircular blade  472 , an intermediate semicircular flange  474  and a neck portion  476 . When assembled, the neck portion  476  fits within the semicircular frame  396  and the intermediate flange  474  sets onto the flange portion  398 . A tapered pin  477  and one or more machine screws connect the cutter head intermediate flange  474  to the cutter body flange portion  398 . 
     On the distal end  43  of the cutter shaft  40  is a shaft end cap  480  and a plurality of small O-rings  482  which, when assembled, act to close the axial channels  192 ,  194 ,  196 ,  197  which can be drilled from the axial distal end  43  of the shaft during manufacture thereof. 
     FIGS. 6 and 7 illustrate the fitting relationship of the cutter assembly  341  into the shaft  40 . The cutter assembly  341  fits within the radial bore  224  in the shaft  40 . The body portion  350  includes upper and lower annular raised regions  484 ,  485  respectively. The raised regions  484 ,  485  are sealed to the inside surface of the radial bore  224  by the O-rings  370 ,  372 ,  376 . An annular space  486  for circulating cooling fluid is located between the raised regions  484 ,  485 . 
     The hold down plate  287  is used to capture an edge  488  of the body portion  350  to hold the body portion  350  onto the shaft  40 . Below the O-ring  376  is an annular space  490  between an inside of the bore  224  and an outside of the body portion  350 . The annular space  490  is in flow communication with the axial channel  192 . The body portion  350  includes radial openings  492  spaced around the circumference of the body portion that flow connect an inside of the body portion to the annular space  490 . Thus, air can flow from the manifold block  38 , through the union block  36 , through the arcuate channel  184  (FIG.  3 ), through the arcuate channel  194   a , through the radial channel  194   b  (FIG.  8 ), through the axial channel  192 , through the annular space  490 , through the openings  492 , through the volume  494 , and out of the apertures  382 . 
     Cooling fluid can flow from the manifold block  38 , through the rotary union  36 , through the arcuate channel  184 , through the arcuate channel  194   a , through the radial channel  194   b , through the axial channel  194 , through the annular space  486 , and out through the axial channel  196 , through the radial channel  196   b , through the arcuate channel  196   a , through the arcuate channel  186 , through the rotary union  36 , and out through the manifold block  38 . The axial channels  194 ,  196  open up into the bore  224  at elongated orifices  194   c ,  196   c  respectively. The orifices  194   c ,  196   c  are open into the annular space  486 . 
     FIGS. 9 and 10 illustrate in detail the structure of the cutter head  470  of the invention. The leading edge  500  of the blade includes tapered or relief areas  502 ,  504  on opposite lateral leading edges of the blade  472 . These relief areas  502 ,  504  help to prevent the pellet from sticking on the blade. The intermediate flange  474  includes one large through hole  512  for receiving the tapered alignment pin  477  for aligning the cutter blade  470  with the flange  398  of the body portion  350 . Also included are two smaller holes  514  and  516 , slightly oversized, for receiving corresponding fasteners for connecting the cutter head  470  to the flange  398 . The flange  398  includes a corresponding alignment hole  512   a  for receiving the pin  477 , and two corresponding threaded holes  514   a ,  516   a  for threadedly receiving the fasteners. Thus, the precisely located and machined alignment holes  512 ,  512   a  can set the precise position of the cutter head  470  with respect to the body portion  350  and the oversized holes  514 ,  516  cab accommodate relative adjustment between the head  470  and the body portion  350 . 
     FIG. 11 illustrates an alternate shaft  640  which holds plural cutter assemblies  341 . The air channel  192  is shown as continuing past the first cutter assembly  341  via an extension channel  193  to deliver air to a second cutter assembly  341 . Alternatively, controlled, separate air channels from the manifold block  38  to each cutter assembly could be used to deliver air to the plural cutter assemblies for more accurate sequentially timed control of individual cutter assemblies. Although two cutter assemblies  341  are shown, other numbers of cutter assemblies, such as four in series, or diametrically opposing banks of four cutter assemblies in series, are encompassed by the invention. 
     The plural cutter assemblies are advantageously associated with plural nozzles  60 , one located at each cutter assembly. Pending patent application U.S. Ser. No. 09/444,814, filed Nov. 22, 1999, filed on the same day as the present application, and identified by attorney docket number HCI0467P0470US, and herein incorporated by reference, describes a molten plastic cutting and delivery system using four cutters in a bank, or two diametrically opposing banks of four cutters each, which face four molten plastic delivery nozzles for delivering four pellets to successive blocks of four molding cavities. The blocks are successively presented to the cutters by a rotating carousel. 
     For the shaft  640  having plural cutter assemblies  341 , the cooling fluid channels would also be extended to and from each sequential cutter assembly  341  in a same fashion as the air channel  192  is extended by the extension channel  193 . 
     FIG. 12 illustrates in schematic fashion the operation of the single cutter of the present invention. Particularly, the precision servo motor  30  is controlled by a controller  740  for precise synchronized positioning of the cutter blade or head  74 ,  470  with the cavities in the carousel. A programmable logic controller (PLC) is used to control this position. U.S. Pat. 5,596,251, herein incorporated by reference, describes a control system for synchronizing a cutter with associated mold cavities on a carousel. 
     The rotary cutter blade or head  74 ,  470  sweeps by the extrusion nozzle and cuts and removes a pellet of molten plastic. At a short time thereafter as the cutter approaches the respective cavity, arranged below, the controller  740  acts on a high speed solenoid valve  750  to admit a burst of air into the manifold block  38 . Air is thereby injected into the cutter body through the passages of the rotary union and the shaft as previously described. 
     According to the first described embodiment, the air acts to extend the plunger to eject the pellet with some amount of air being passed through the perforated plate  251  to impinge upon the molten plastic pellet to help displace the pellet from the cutter blade  74  and into the respective cavity. After the pellet is ejected, the controller switches the solenoid valve  750  to vent through the passages which were used previously to extend the plunger, and pressurized air is injected into a different port of the manifold block which directs the air through the rotary union and the shaft to an upper side of the plunger to force the plunger into a retracted position. During plunger extension to eject a pellet, this other port of the manifold block is vented. 
     According to the second described embodiment, the air is directed through the perforated plate  380  to impinge on the plastic pellet to displace the pellet from the cutter blade  472  and into the respective cavity. 
     Compared to the arrangement in prior art U.S. Pat. No. 4,277,431, no flexible blade is needed to “fling” or eject the plastic pellet from the blade into the cavity. Accordingly, cutter blade  74  is substantially rigid and non-flexible, and preferably configured to move relative to the associated nozzle without any interfering engagement therewith. And unlike the device disclosed in U.S. Pat. No. 5,596,251 no electronically created deceleration of the cutter is required for pellet ejection. 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.