Abstract:
An injection molding machine is provided, including a nozzle assembly having a channel for conveying a fluid. At least one cavity insert is removably mounted within a cavity plate, the at least one cavity insert defining a mold cavity, and a first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity. A gate insert defines a receptacle for the nozzle assembly, and further defining a second portion of the gate. The gate insert is floatably retained between the nozzle assembly and the at least one cavity insert. Preferably, the gate insert is retained by a gate insert plate that is disposed between the cavity plate and the nozzle assembly.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates, generally, to injection molding systems. More particularly, the invention relates to the interface between inserts in a molding assembly. 
       BACKGROUND OF THE INVENTION 
       [0002]    Injection molding is a commonly employed manufacturing technique for forming articles. An example of an article that is typically formed using injection molding is a plastic preform. A plastic preform can then be subsequently blow-molded into a plastic bottle. 
         [0003]    An injection mold for making preforms (and other molded articles) typically includes one or more molding cavities for receiving molten resin and forming the preforms. To increase the flexibility of the molding assembly, interchangeable inserts can be inserted into bores in a cavity plate.  FIG. 1  shows a portion of a prior art injection molding machine  10 . One or more mold cavities  12  are usually defined between complementary shaped, generally cylindrical cavity inserts  14  and core inserts  15  that are arranged within bores in a cavity plate  16 . The mold cavities  12  are aligned generally parallel to the direction of mold-clamping action (i.e., the mold-clamping axis). 
         [0004]    For mold articles that have threaded neck portions, a split neck ring (not shown) cooperates with the core insert  15  to create the neck. A taper is typically provided at an end of the cavity insert  14  (also not shown) to help align the neck ring. 
         [0005]    A hot runner assembly  18  communicates a flow of molten resin to melt channels  19  in one or more nozzle assemblies  20 . A gate insert  22  is seated within the mold cavity inserts  14 . A first profiled surface  24  on gate insert  22  defines a receptacle to house the tip of the nozzle assembly  20 . A second profiled surface  26  on the gate insert  22  defines a portion of the mold cavity  12 . A gate  28  is provided in gate insert  22  which provides fluid communication between the nozzle assemblies  20  and each of the mold cavities  12 . Gate  28  is open or closed by a piston valve  29 . Other types of gating, such as slide valves or thermal gating can also be used 
         [0006]    The molten resin that is injected into the cavities must be cooled to solidify the resin so that the molded preform can be removed from the mold. It is desirable to cool the preform as quickly as possible so the preforms can be removed and a next injection cycle initiated with minimal time delay. To this effect, cooling channels  30  are typically provided in the cavity and gate inserts  14  and  22 . A cooling fluid, such as water, is circulated through the cooling channels  30 . 
         [0007]    The use of mold cavity inserts  14  and gate inserts  22  increases the machine&#39;s flexibility, as the inserts can be switched to produce a different molded object without the need to remove the cavity plate  16  from the molding assembly  10 . However, before the cavity inserts  14  and gate inserts  22  can be safely removed, the nozzle assemblies  20 , which may contain still-hot molten resin, must be allowed to cool. 
         [0008]    Efforts have been made to improve mold assemblies. U.S. Pat. No. 6,398,542 to Romanski et al. teaches a valve gating apparatus for injection molding including at least one shutter disposed between the gate and the cavity melt channel into a mold cavity. The shutter is removably fastened to a rail member. When the rail member is moved laterally, the shutter moves between a closed position wherein flow of melt from the nozzle into the cavity is inhibited, and an open position wherein flow of melt into the cavity is unimpeded by the shutter. In a preferred embodiment, a sliding gate valve with inserts that includes a hot runner insert around the injection nozzle and a gate insert which defines a portion of the mold cavity. The gate between the injection nozzle and the mold cavity is defined and split between the hot runner insert and the gate insert. The hot runner insert is retained by the manifold plate of the hot runner assembly, and the gate insert is retained by the cavity plate. 
         [0009]    U.S. patent application 2006/0099295 to Elliot teaches a gate insert for a stack assembly in an injection molding machine having a gate through which a melt of thermoplastics material enters a mold cavity. The gate insert has a cooling channel surrounding, and substantially uniformly spaced from, the gate. The cooling channel has an inner surface with a profile substantially parallel to the gate. The cooling channel is further defined by a two-piece gate insert having interconnecting surfaces. 
         [0010]    U.S. patent application 2005/0236725 to Niewels et al. teaches a method and apparatus for controlling an injection mold having a first surface and a second surface includes an active material element configured to be disposed between the first surface and a second surface. The active material element may be configured to sense a force between the first surface and the second surface, and to generate corresponding sense signals. Transmission structure is coupled to the active material element and is configured to carry the sense signals. Preferably, an active material element actuator is also disposed between the first surface and a second surface, and is configured to provide an expansive force between the first surface and a second surface in accordance with the sense signals. The method and apparatus may be used to counter undesired deflection and/or misalignment in an injection mold. The active material actuator is operable to “tilt” a core element when misalignment occurs. 
         [0011]    U.S. Pat. No. 5,736,173 to Wright et al. teaches a preform injection mould includes an elongate mould core cooperating with a female mould and a neck ring in a manner to define a mould cavity therebetween. An injection nozzle in the female mould allows molten plastic to be injected into the mould cavity so that a preform molded article may be formed. The neck ring is constituted by a pair of mating halves which can be separated laterally with respect to the longitudinal axis of the mould core. A taper sleeve surrounds the mould core beneath the neck ring. The neck ring halves are secured to diametrically opposed slides to facilitate lateral separation of the neck ring. A pair of slide taper locks contact a respective one of the slides to inhibit lateral movement of the slides and to back up the neck ring when injection mould is in a mould closed position. An annular formation is formed on the upper surface of the neck ring and is accommodated by a complementary recess formed in the bottom of the female mould. The mating inclined surfaces of the female mould and the annular formation constitute an upper taper lock which is backed up by a cavity plate. An annular formation is provided on the upper surface of the taper sleeve and is accommodated by a complimentary recess formed in the bottom of the neck ring. The mating inclined surfaces of the taper sleeve and neck ring constitute a lower taper lock. Since a portion of the neck ring constitutes the female taper of the lower taper lock, the lower taper lock is backed up by the slide taper locks through the slides allowing the cross-sectional area of the neck ring to be reduced. 
         [0012]    U.S. Pat. No. 6,569,370 to Amin et al. teaches an injection molding system for molding a molded article and method for forming same, including a mold cavity for forming the molded article, wherein the mold cavity is defined at least in part by a mold core defining inner walls of the molded article, a first insert defining at least outer side walls of the molded article, and a second insert defining an outer wall of a neck of the molded article. In addition, a cavity plate at least partly surrounds the first insert and a cavity flange retains the first insert in the cavity plate. 
       SUMMARY OF THE INVENTION 
       [0013]    According to a first broad aspect of the invention, there is provided an injection molding machine, including a nozzle assembly having a channel for conveying a fluid. At least one cavity insert is removably mounted within a cavity plate, the at least one cavity insert defining a mold cavity, and a first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity. A gate insert defines a receptacle for the nozzle assembly, and further defining a second portion of the gate. The gate insert is floatably retained between the nozzle assembly and the at least one cavity insert. 
         [0014]    According to a second broad aspect of the invention, there is provided a mold assembly for an injection molding machine having a stationary portion and a moving portion, and a nozzle assembly for conveying a fluid. A mold cavity is defined by at least one cavity insert on the stationary portion. A mold core is defined on the moving portion. A gate insert is floatably retained on the stationary portion between the at least one cavity insert and the nozzle assembly and providing a receptacle for the nozzle assembly. A first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity is defined within the gate insert and a second portion of the gate is defined within the at least one cavity insert. 
         [0015]    According to a third broad aspect of the invention, there is provided a gate insert plate for an injection molding machine having a nozzle assembly and a mold cavity. The gate insert plate is located between the nozzle assembly and the mold cavity. The gate insert plate includes a bore for coaxially seating a gate insert which defines a gate for fluid communication between the nozzle assembly of the injection molding machine and the mold cavity. 
         [0016]    According to a fourth broad aspect of the invention, there is provided a gate for fluid communication between a nozzle assembly of an injection molding machine and at least one cavity insert defining a mold cavity. The gate has a first portion defined by a gate insert that is floatably retained between the nozzle assembly and the at least one cavity insert and a second portion defined by the at least one cavity insert. 
         [0017]    According to a fifth broad aspect of the invention, there is provided a gate insert defining a receptacle for a nozzle assembly of an injection molding machine and further defining a portion of a gate for fluid communication between the nozzle assembly of the injection molding machine and a mold cavity. The gate insert is retained by a gate insert plate that is disposed between the mold cavity and the nozzle assembly. 
         [0018]    According to a sixth broad aspect of the invention, there is provided an injection molding machine. The injection molding machine includes a nozzle assembly having a channel for conveying a fluid. At least one cavity insert is removably mounted within a cavity plate, the at least one cavity insert defining a mold cavity and a first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity. A gate insert defines a receptacle for the nozzle assembly, and further defining a second portion of the gate. The gate insert is retained by a gate insert plate that is disposed between the cavity plate and the nozzle assembly. 
         [0019]    According to a seventh broad aspect of the invention, there is provided a mold assembly for an injection molding machine having a stationary portion and a moving portion, and a nozzle assembly for conveying a fluid. The mold assembly includes a mold cavity being defined by at least one cavity insert on the stationary portion, and a mold core being defined on the moving portion. A gate insert is retained on the stationary portion by a gate insert plate between the at least one cavity insert and the nozzle assembly and providing a receptacle for the nozzle assembly. A first portion of a gate for communicating the fluid between the nozzle assembly and the mold cavity is defined within the gate insert and a second portion of the gate is defined within the at least one cavity insert. 
     
    
     
       DETAILED DESCRIPTION OF DRAWINGS 
         [0020]    Objects and advantages of the present invention will become apparent to those skilled in the art upon reading the following detailed description of non-limiting embodiments of the present invention, in conjunction with the accompanying drawings, wherein like reference numerals have been used to designate like elements, and wherein: 
           [0021]      FIG. 1  shows a cross section view of a stationary portion of a prior art injection molding machine; 
           [0022]      FIG. 2  shows a perspective view of a stationary portion of an injection molding machine in accordance with a first non-limiting embodiment of the invention; 
           [0023]      FIG. 3  shows a first cross section view of the stationary portion shown in  FIG. 2 ; 
           [0024]      FIG. 4  shows a second cross section view of the stationary portion shown in  FIG. 2 ; 
           [0025]      FIG. 5  shows a front plan view of a gate insert plate for the stationary portion shown in  FIG. 2 ; 
           [0026]      FIG. 6  shows a cross section view of a cavity insert plate for the stationary portion shown in  FIG. 2 ; 
           [0027]      FIG. 7  shows a cross section view of a portion of a core insert plate for a moving portion of a hot runner assembly; 
           [0028]      FIG. 8  shows a perspective view of a taper insert plate for the stationary portion shown in  FIG. 2 ; 
           [0029]      FIG. 9  shows a cross section view of a cavity insert plate for the stationary portion shown in  FIG. 2 , in accordance with a second non-limiting embodiment of the invention; 
           [0030]      FIG. 10  shows a cross section view of a gate insert for the stationary portion shown in  FIG. 2 , in accordance with a third non-limiting embodiment of the invention; and 
           [0031]      FIG. 11  shows a cross section view of a cavity insert plate for the stationary portion shown in  FIG. 2 , in accordance with a fourth non-limiting embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0032]    Referring to  FIGS. 2-4 , a stationary portion of a multi-cavity injection molding machine in accordance with a first non-limiting embodiment of the invention is shown generally at  40 . The stationary portion  40  includes a manifold backing plate  42 , a manifold plate  44 , a gate insert plate  46 , a cavity plate  48  and a taper insert plate  50 . 
         [0033]    A hot runner system  52  is provided within stationary portion  40  which provides a fluid, typically molten resin to one or more nozzle assemblies  54  that are distributed across the system. The implementation of the nozzle assemblies  54  is not particularly limited and can include both thermal gated and valve gated nozzle assemblies. It is contemplated that the present invention is particularly suited to, but not necessarily limited to, injection molding machines that produce polyethylene teraphthalate (PET) preforms. The molten resin is supplied to hot runner system  52  from a resin source, typically a hopper feeding resin pellets to a plasticizer (not shown) and thence to a main melt channel  56 . Main melt channel  56  conveys the now molten resin to the manifold  57 . As is well known, the manifold  57  has a number of manifold melt channels  58  through which the molten resin travels to nozzle assemblies  54  while it is maintained at an optimum processing temperature by manifold heaters  60 . 
         [0034]    Each of the nozzle assemblies  54  is coaxially located within a bore  62  provided in the manifold plate  44 , sandwiched between manifold backing plate  42  and the gate insert plate  46 . Each of the nozzle assemblies  54  generally includes a generally conical nozzle sheath  64  in which is held a nozzle tip  66  through which runs a nozzle channel  68  that is in communication with one of the manifold melt channels  58 . In the presently illustrated embodiment, nozzle assemblies  54  are valve gated. A valve stem  70  is operable to be reciprocated by a piston  72  between an opened and a closed position. In the open position, resin exits each of the nozzle assemblies  54  through nozzle tip  66  and out through a gate  74  (best seen in  FIG. 6  and described in greater detail below). In the closed position (as shown in  FIG. 3 ), valve stem  70  closes off gate  74 , preventing the resin from exiting through the nozzle tip  66 . A nozzle heater  76  maintains nozzle tip  66  at a relatively high temperature, determined by the molten resin being injected. However, the invention is not particularly limited to nozzle assemblies  54  that use valve gates, and other types of nozzle assemblies are within the scope of the invention. 
         [0035]    Manifold plate  44 , gate insert plate  46  and cavity plate  48  are mounted and aligned together in stationary portion  40  via fasteners  78  which extend through coaxial apertures  80  in each of the three plates. Gate insert plate  46  is also directly mounted to manifold plate  44  via fasteners  82  which extend through coaxial apertures  84  in the two plates. It will thus be apparent that cavity plate  48  can be removed from stationary portion  40  without removing gate insert plate  46  from the manifold plate  44 . 
         [0036]    Referring now to  FIGS. 5 and 6 , in addition to  FIG. 3 , distributed across gate insert plate  46  are a plurality of gate bores  86  that are coaxially aligned with nozzle assemblies  54  (and thus generally aligned with the axis of mold clamping). Each of the gate bores  86  is adapted to receive a gate insert  88 . Each of the gate bores  86  narrows to provide a gate land  89  which supports a flange  90  on the gate insert  88  in order to retain the gate insert in a “floating” fit so that the gate insert  88  can slide along a plane generally traverse to the mold-clamping axis. When properly seated in its respective gate bore  86 , the gate insert  88  is recessed fully within the plane of the gate insert plate  46 . A profiled surface  91  within gate insert  88  defines a receptacle for the nozzle sheath  64 . The profiled surface  91  is complementary to nozzle sheath  64 , thereby substantially and coaxially aligning each of the nozzle assemblies  54  with their respective gate insert  88 . As is known to those of skill in the art, a gate insert  88  can be replaced by the repeated wear and tear of opening and closing of gate  74 . If desired, profiled surface  91  can be lined with an insulating material to reduce unwanted heat transference from the nozzle assemblies  54  to gate insert plate  46 . 
         [0037]    A first portion of the gate  74  is defined with gate insert  88 , extending from the tip of profiled surface  91  in gate insert  88  towards a mold cavity  92  located within cavity plate  48 . Gate  74  is in communication with both the nozzle channel  68  and mold cavity  92 , thereby permitting the flow of molten resin from the first to the latter. Since the gate insert  88  is retained by the gate insert plate  46 , the gate insert  88  covers the nozzle assembly  54  even when the cavity plate  48  is removed. 
         [0038]    The mold cavity  92 , which defines an exterior surface of a molded object such as a preform (not shown), is generally defined by at least one cavity insert, and specifically in the currently illustrated embodiment by a first cavity insert  100  and a second cavity insert  102 . Each first cavity insert  100  is retained within a cavity bore  101  in cavity plate  48 . An insert land portion  103  of cavity bore  101  prevents first cavity insert  100  from exiting out of the cavity plate  48  in a non-preferred direction. Second cavity insert  102  is coaxial with the first cavity insert  100  and seated on an insert land  105  on first cavity insert  100 . It will be apparent from the figures that a first portion of gate  74  is defined by gate insert  88  and that a second portion of gate  74  is defined by first cavity insert  100 . Gate insert  88  and first cavity insert  100  float relative to one another on an axis generally traverse to the mold clamping axis, providing a sliding, or “floating” interface between the two halves of gate  74 . 
         [0039]    Cooling channels  104  are typically provided in first cavity insert  100  to cool the resin injected into the mold cavity  92 . In addition, a cooling channel  106  is defined in a gap between the second cavity insert  102  and cavity plate  48 . Cooling channel  106  is operable to receive a cooling mold cavity insert (not shown), as is described in pending U.S. application Ser. No. 11/254,325, entitled “Molding Insert with a Cooling Channel Insert”, and filed on Oct. 20, 2005. A cooling fluid, such as water is circulated through the cooling channels  104  and  106  (via the mold cavity insert) during a cooling phase of an injection cycle, as will be further described below. Referring in addition to  FIG. 2 , the cooling fluid enters the cavity plate  48  through inlet  108  and is routed to cooling channels  104  and  106  via transport channels  111  ( FIG. 3 ) in the cavity plate  48 . After completing its circuit, the cooling fluid exits cavity insert plate the through outlet  112 . Seal niches  114  are provided to locate rubberized seals and prevent leakage between first cavity inserts  100  and second cavity inserts  102 . 
         [0040]    Referring now to  FIG. 7 , a portion of a moving portion  116  for an injection molding machine is shown. A core member  118  is mounted to a core plate  119  via fasteners  121 . Core member  118  cooperates with first cavity insert  100  and second cavity insert  102  to define the mold cavity  92 . Core member  118  defines a mold core, shaping the inner surface of the preform. A core taper  120  is provided on core member  118  to help align core member  118  with mold cavity  92  during closure of the two mold halves. Core member  118  includes a cooling tube  122  to cool the interior surface of the preform. A cooling fluid, such as water is circulated through the cooling tube  122  during a cooling phase of an injection cycle, as will be further described below. The cooling fluid is routed to cooling tube  122  via transport channels  125  in the core plate  119 . The cooling water then runs down the annular tube  127  and is subsequently removed from core plate  119  out through return channel  129 . 
         [0041]    Referring back to  FIG. 6 , and additionally to  FIG. 8 , taper insert plate  50  insert is mounted to cavity plate  48  via fasteners  123  which extend through coaxial apertures  124  in both of the plates. Distributed across taper insert plate  50  are a plurality of taper insert bores  126  that are coaxially aligned with the mold axis defined by nozzle assemblies  54 . Each of the taper insert bores  126  is adapted to receive a taper insert  128 . Taper insert  128  retains the second cavity insert  102  within its cavity bore  101 , and is in turn, retained by taper insert plate  50 . Each taper insert  128  includes a cavity plate land  130  which abuts against cavity plate  48 , a cavity insert land  132  which abuts against the second cavity insert  102 , and a taper plate land  134  which abuts against taper insert plate  50 , thereby retaining the taper insert  128  in a floating fit between taper insert plate  50  and second cavity insert  102 . In addition, first cavity insert  100  and second cavity insert  102  now float between gate insert  88  and taper insert  128  along an axis generally traverse to the mold-clamping axis. 
         [0042]    When properly seated in its respective taper insert bore  126 , the taper insert  128  is recessed fully within the plane of the taper insert plate  50 . Taper insert  128  further includes a tapered surface  136  which helps locate a neck ring (not shown) during the insertion of the core member  118  into the mold cavity  92  during the injection cycle. A seal niche  138  is provided to locate a rubberized seal  139  and prevent leakage between taper insert  128  and cavity plate  48 . 
         [0043]    Referring now to  FIG. 9 , a stationary portion of a multi-cavity injection molding machine in accordance with a second non-limiting embodiment of the invention is shown generally at  140 . Stationary portion  140  includes a gate insert plate  146 , a cavity plate  148 , and a taper insert plate  150 . A gate insert  188  is seated within a gate bore  186  in the gate insert plate  146 . A first portion of a gate  174  is defined within gate insert  188 . A cooling channel  190  is defined within gate insert  188  to reduce heat transference from nozzle assembly  54  ( FIG. 3 ) to a cavity  192 , which is defined between a cavity insert  200  and a core member  218  which is mounted to the moving portion (not shown). In the illustrated embodiment, a cooling fluid, such as water, is circulated through the cooling channels  190  during a cooling phase of an injection cycle, as will be further described below. The cooling fluid is routed to cooling channels  190  via transport channels (not shown) in the gate insert plate  146 . An additional cooling channel  214  is defined between a taper insert  228  and taper insert plate  150 . The cooling fluid is routed to cooling channel  214  via transport channels  215  in the gate taper insert plate  150   
         [0044]    The cavity insert  200  is seated within a cavity bore  201  within cavity plate  148 . A second portion of gate  174  is defined within cavity insert  200  that is in floating communication with the first portion of gate  174 . The exterior surface of the preform is defined by the single cavity insert  200 . Gate insert  188  includes a tapered portion  202 , and cavity insert  200  include a complementary tapered portion  204 , to substantially and coaxially align the two inserts together. The interface between tapered portion  202  and  204  allows cooling channel  190  to be located closer to cavity  192 , thereby increasing the cooling efficiency of the cooling channel  190 . 
         [0045]    Gate insert plate  146  includes tapered side portions  206  along a sidewall  208  of gate bore  186  to reduce the force required for the insertion of gate insert  188  into gate bore  186 . In addition, a gap  210  is provided between the edge of a flange  212  on gate insert  188  and sidewall  208 . Given the tapering, there is minimal float for the gate insert  188  traverse to the mold-clamping axis than in the embodiment described in  FIG. 6 . It is contemplated that clearance could be provided between tapered portions  202  and  24  should a greater degree of float be desired. 
         [0046]    Referring now to  FIG. 10 , a gate insert in accordance with a third non-limiting embodiment of the invention is shown at  288 . A first portion of a gate  274  is defined by gate insert  288  and a second portion of gate  74  is defined by a first cavity insert  300  (which defines a portion of a cavity  292 ). Gate insert  288  and first cavity insert  300  float relative to one another on an axis generally traverse to the mold clamping axis, providing a sliding, or “floating” interface between the two halves of gate  274 . 
         [0047]    A cooling channel  290  is cooperatively defined between gate insert  288  and cavity insert  300  to reduce heat transference from nozzle assembly  54  to a cavity  192 . A cooling fluid, such as water, is circulated through the cooling channels  190  during a cooling phase of an injection. By splitting the cooling channel  290  between gate insert  288  and cavity insert  300 , the machining of the cooling channel  290  is simplified. Seal niches  314  are provided to locate rubberized seals and prevent leakage into cavity  292 . 
         [0048]    Referring now to  FIG. 11 , a second cavity insert having an integral taper is shown at  402 . Second cavity insert  402  is retained at one end by a first cavity insert  100 , as is described above, and is retained at the other end by taper insert plate  50 . Each second cavity insert  402  includes a cavity plate land  430  which abuts against cavity plate  48 , and a taper plate land  434  which abuts against taper insert plate  50 , thereby retaining the second cavity insert  402  in a floating fit between taper insert plate  50  and first cavity insert  400 . Second cavity insert  402  further includes a tapered surface  436  which helps locate a neck ring (not shown) during the insertion of the core member (also not shown) into the mold cavity  92  during the injection cycle. A seal niche  438  is provided to locate a rubberized seal and prevent leakage between second cavity insert  402  and cavity plate  48 . 
         [0049]    The operation of the present invention will now be described over the course of an injection cycle, with reference to  FIGS. 2-3 . In a typical injection cycle, valve stem  70  is retracted by piston  72  to open the gate  74 . Molten resin, fed by hot runner system  52  to nozzle channel  68 , and hence to nozzle tip  66 , is conveyed under pressure to mold cavity  92  through gate  74 . Throughout the cycle, nozzle heaters  76  to maintain resin in nozzle channel  68  at an optimum processing temperature. Once the mold is full, valve stem  70  is advanced to seat in gate  74  to stop the flow of resin. The cooling channels  104  and  106 , and the cooling tube  122  circulate water to remove heat from the resin, causing it to freeze into the shape of the preform. The mold opens and the preform is ejected (not discussed). The mold then closes, and the cycle repeats. 
         [0050]    After a number of cycles, an operator may wish to exchange the first cavity inserts  100  and second cavity inserts  102 , typically in order to provide a different cavity shape. The operator will remove the taper insert plate  50 . Taper inserts  128  can be exchanged, if needed. Although nozzle assemblies  54  remain dangerously hot, the operator will be able to slide the first cavity inserts  100  and second cavity inserts  102  out of cavity bore  101  since gate insert  88  fully covers the nozzle assembly. 
         [0051]    Non-limiting embodiments of the present invention can decrease the amount of time required that operators must wait before exchanging cavity inserts as the nozzle assemblies remain covered by the gate inserts during the conversion. Non-limiting embodiments of the present invention can reduce cycle time due to cooling efficiency in the gate and taper inserts. In addition, non-limiting embodiments of the present invention can reduce the wear and tear on the gate and taper inserts due to the inserts being seated in a floating arrangement. Furthermore, non-limiting embodiments of the present invention can reduce the cost for prototype stacks as the gate and taper inserts are machined independently of the cavity inserts. 
         [0052]    The description of the exemplary embodiments provides examples of the present invention, and these examples do not limit the scope of the present invention. It is understood that the scope of the present invention is limited by the claims. The concepts described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present invention. Having thus described the exemplary embodiments, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims.