Abstract:
A flange is provided for aligning an injection molding nozzle with a mold gate and insulating the injection molding nozzle from a mold plate. The flange is separate from the nozzle and is releasably connected to a body of the nozzle adjacent to a nozzle head. When the flange and nozzle are coupled, they can be inserted into and removed from a nozzle recess included within the mold plate as a unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims the benefit under 35 U.S.C. §119(e) of, U.S. Provisional Application No. 60/480,404 filed Jun. 23, 2003. The disclosure of this referenced application is incorporated by reference herein in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to nozzles for an injection molding apparatus. In particular, the present invention relates to injection molding nozzles having a separate collar.  
           [0004]    2. Background of the Invention  
           [0005]    In general, a hot runner nozzle includes a nozzle tip, a nozzle body and a nozzle head. A nozzle flange, or collar, is also usually provided to locate the nozzle body relative to a mold plate in which the nozzle is mounted.  
           [0006]    Proper alignment of the components of an injection molding apparatus is desired for the production of quality-molded parts. If the hot runner nozzle is not properly aligned with the mold gate, sealing or gating may be adversely affected. In thermal gating applications, alignment of the nozzle tip with the mold gate is important in order to prevent leakage of the molten material. In valve gated applications, alignment of the nozzle tip with the mold gate is important because the valve pin, which is able to slide through the nozzle, must be properly aligned with the mold gate in order to close the gate effectively.  
           [0007]    Installation and alignment of a nozzle with an integrated flange is relatively simple because there is no movement between the parts. In some applications, a flange constructed of a material different than that of the nozzle body is desired and is permanently coupled to the nozzle. An advantage of this arrangement is that a material that is less thermally conductive than the nozzle may be used to reduce the heat loss between the nozzle and the mold plate. In this way, it is possible to create a custom nozzle to match the requirements of a particular molding process.  
           [0008]    It is often advantageous for the flange to be a separate part that is removable from the nozzle. Because the flange is not attached to the nozzle, it can be easily replaced or used with a different nozzle to suit different injection molding applications. For example, if more insulation between the nozzle and the mold plate is desired, a collar constructed from a ceramic material may be used instead of a steel collar.  
           [0009]    With respect to systems employing separate flanges, there is a need for a flange that can be reliably connected to and properly aligned with the nozzle so that the combination of the nozzle and flange can be inserted into or removed from a mold plate as a unit. In addition, there is a need for a separate flange that is simple and efficient to install and remove from the nozzle. There is a further need for a nozzle having a separate flange that is compact so that the combination is compatible in tight pitch molding applications.  
         SUMMARY OF THE INVENTION  
         [0010]    According to one aspect of the invention, there is provided an injection molding apparatus having a manifold, a mold plate including a recess for receiving a nozzle, and a separate flange mounted on a body of the nozzle for aligning the nozzle relative to the mold plate. The flange has a surface engaging the nozzle body that aligns the nozzle within the flange. A second surface of the flange engages the mold and bears against the inner surface of the recess to align the flange within the recess. A connector is provided to releasably connect the flange to the nozzle body.  
           [0011]    According to another aspect of the invention, a hot runner nozzle is provided that includes a nozzle body having an outer surface and a nozzle head, a separate flange mounted on the nozzle body adjacent to the nozzle head, and a connector for releasably connecting the nozzle body and the separate flange.  
           [0012]    Further features and advantages of the invention, as well as the structure and operation of sample embodiments of the invention, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art based on the teachings contained herein. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0013]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings.  
         [0014]    [0014]FIG. 1 is a cross-sectional view of a portion of an injection molding apparatus showing an injection molding nozzle and a separate flange according to one aspect of the present invention.  
         [0015]    [0015]FIG. 2A is a schematic view showing a connector in a securing position for securing a separate flange to the nozzle of FIG. 1.  
         [0016]    [0016]FIG. 2B is a schematic view showing the connector in FIG. 2A in a released position.  
         [0017]    [0017]FIG. 3A is a partial cross-sectional side view showing the flange secured to the nozzle of FIG. 1.  
         [0018]    [0018]FIG. 3B is a partial cross-sectional side view showing the flange released from the nozzle of FIG. 1.  
         [0019]    [0019]FIG. 4A is an enlarged view of a portion  4 A of FIG. 3A.  
         [0020]    [0020]FIG. 4B is an enlarged view of a portion  4 B of FIG. 3B.  
         [0021]    [0021]FIG. 5 is a side view of a portion of the nozzle and flange combination of FIG. 1.  
         [0022]    [0022]FIG. 6 is a partial sectional view of an injection molding apparatus. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    Specific embodiments of the present invention are now described with reference to the figures, where like reference numbers indicate identical or functionally similar elements.  
         [0024]    Referring first to FIG. 6, one example of an injection molding apparatus  10  in which the present invention may be utilized is shown. The injection molding apparatus includes a machine nozzle  11 , which introduces a melt stream under pressure into the injection molding system via a sprue bushing  16  that is positioned within a machine platen  31 . From sprue bushing  16 , melt flows into a manifold melt channel  14  provided in a hot runner manifold  12 . In injection molding apparatus  10 , manifold  12  allows the melt stream to be distributed through nozzle melt channel inlets  20  and into nozzle melt channels  22  provided in respective nozzles  18 . Nozzles  18  are positioned within nozzle cavities, or recesses  36  of a mold plate  32 . Each nozzle  18  is in fluid communication with a mold cavity  34  via a mold gate  24  so that the melt stream may be injected through nozzle melt channel  22  and nozzle tip  30  into mold cavities  34 .  
         [0025]    Referring to FIG. 1, a cross-sectional view of nozzle  18 , provided in injection molding apparatus  10 , is shown. Nozzle  18  has a nozzle melt channel inlet  20 , at an upper end of nozzle melt channel  22 , aligned with an outlet of manifold melt channel  14  to receive the melt stream and to deliver the melt through mold gate  24  to mold cavity  34 . Nozzle  18  has a nozzle body  28 , a nozzle head  26 , and a nozzle tip  30 . As shown, nozzle tip  30  is held in nozzle body  28  by a nozzle retainer  33 . The nozzle head  26  is an upper portion of nozzle  18  that provides space for connecting a terminal connector  44 . In the embodiment shown, nozzle head  26  is enlarged or has a radial dimension larger than a radial dimension of nozzle body  28 . However, it shall be appreciated that nozzle head  26  need not be enlarged and may have a radial dimension that is equal to or less than the radial dimension of nozzle body  28 . Injection molding apparatus  10  may include any number of such nozzles located in respective nozzle recesses  36  for transmitting melt from respective nozzle melt channel inlets  20  to respective mold gates  24 .  
         [0026]    In one embodiment, a shoulder  38  is formed on an inner wall  40  of nozzle recess  36 . A generally cylindrical flange  42  surrounds a portion of the nozzle  18 . Flange  42  is positioned between nozzle head  26  and shoulder  38  and aligns nozzle  18  with mold gate  24 . Flange  42  supports nozzle  18  in nozzle recess  36  so that a thermally insulating space is created between nozzle  18  and mold plate  32 .  
         [0027]    As best seen in FIGS. 1 and 5, in the sample embodiment, flange  42  includes a first generally cylindrical portion  60 , a transitional portion  64 , and a second generally cylindrical portion  62 . The portions form a single piece flange  42  with first and second cylindrical portions  60  and  62  spaced apart by transitional portion  64 .  
         [0028]    First cylindrical portion  60  has an inner surface  66  that abuts, or interfaces with, an outer surface  68  of nozzle body  28  below nozzle head  26 . The contact between inner surface  66  and outer surface  68  assures that flange  42  is aligned with nozzle  18  along a longitudinal axis. First cylindrical portion  60  has a top end  54  that bears against a shoulder  56  provided at the bottom of nozzle head  26  and limits the height of flange  42  on nozzle body  28 . As will be explained in greater detail below, and with further reference to FIGS. 4A and 4B, a flange groove  78  is provided in first cylindrical portion  60  of flange  42  and a nozzle groove  76  is provided in nozzle body  28  for housing a connector  70 .  
         [0029]    Transitional portion  64  is generally conical and spans from first cylindrical portion  60  to second cylindrical portion  62 . Transitional portion  64  tapers inward in the direction of mold gate  24  and is located within the thermally insulating air space between nozzle  18  and mold plate  32  so that transitional portion  64  does not contact either nozzle  18  or mold plate  32 .  
         [0030]    Second cylindrical portion  62  of flange  42  has a bottom end  58  for bearing against shoulder  38  provided in nozzle recess  36 . Second cylindrical portion  62  also has an outer surface  63  for abutting an inner surface  72  of nozzle recess  36 . The abutment of outer surface  63  and inner surface  72  aligns the combined flange  42  and nozzle  18  with nozzle recess  36  and therefore mold gate  24 . Circumferential ribs  74  may be provided on the outer surface of second cylindrical portion  62  to reduce the amount of surface area contacting inner surface  72 .  
         [0031]    Flange  42  may be made of any material known in the art for injection molding applications. In order to improve the insulation characteristics of flange  42 , it may be made of a material having a low thermal conductivity such as, for example, titanium or ceramic.  
         [0032]    In another aspect of the present invention, terminal connector  44  is located on nozzle head  26 . Terminal connector  44  houses heater leads  46  for a helical nozzle heater  48  and thermocouple leads  50  for a thermocouple  52  respectively. Helical nozzle heater  48  is embedded in nozzle body  28 . Although an embedded helical nozzle heater  48  is shown, other nozzle heating arrangements may be used. Thermocouple lead  50  passes through terminal connector  44  and extends to thermocouple  52  which is used to measure the temperature of nozzle  18 . It shall be appreciated that any other devices known in the art for monitoring and controlling the temperature of an injection molding nozzle may be employed.  
         [0033]    In the present embodiment, connector  70  is a generally C-shaped spring wire that is housed in flange groove  78 . As shown in FIGS. 2A and 2B, connector  70  can be expanded from a first diameter D 1  to a second larger diameter D 2 . Connector  70  is biased so that it has a tendency to return to the smaller first diameter when no forces are acting upon it. The two ends of connector  70  are bent outwardly and form a fixed end  80  and a movable end  82 .  
         [0034]    As best seen in FIG. 5, fixed end  80  extends into a hole  84  that extends from flange groove  78  and through at least a portion of the wall of flange  42  toward the outer surface of flange  42 . Fixed end  80  prevents connector  70  from rotating within flange groove  78  with respect to flange  42 . Movable end  82  extends through a slot  86  that also extends from flange groove  78  and through the wall of flange  42  toward the outer surface of flange  42 .  
         [0035]    In one aspect of the present invention, movable end  82  extends through the entire wall thickness of flange  42  so that it is accessible from the outside of flange  42 . Since movable end  82  is accessible from the outside of flange  42  it is possible to apply a force in a direction  88 , as shown in FIGS. 2B and 5, to connector  70  by hand.  
         [0036]    Flange groove  78  and connector  70  are sized so that when force in direction  88  is applied to movable end  82 , connector  70  becomes seated entirely within flange groove  78 , as shown in FIGS. 3B and 4B. When no force is applied to movable end  82 , connector  70  is biased inwardly such that connector  70  extends further inward than inner surface  66  of first cylindrical portion  60  of flange  42 , as shown in FIG. 4A.  
         [0037]    Since connector  70  is located partially in nozzle groove  76  and simultaneously partially in flange groove  78 , connector  70  intersects outer surface  68  of nozzle body  28  and inner surface  66  of first cylindrical portion  60  of flange  42 . Nozzle groove  76  is sized so that connector  70  is simultaneously partially seated in nozzle groove  76  and partially seated in flange groove  78 . Since connector  70  is located in both flange groove  78  and nozzle groove  76 , flange  42  is secured in a position relative to nozzle  18  in the longitudinal direction and the overall outer dimension of the combined nozzle and flange is reduced.  
         [0038]    Although connector  70  has been described and illustrated as a generally C-shaped spring wire having a circular cross-section, other connectors may be used to releasably connect flange  42  to nozzle body  28 . The connector may be either deformable or rigid and may have any cross-section. In addition, the connector need not be C-shaped and may be constructed of multiple components. As one alternative, a solid ring may be used to connect the separate parts. In a further alternative, a bump or ball on one part may interface a dimple or groove on the other.  
         [0039]    As suggested above, and as best seen in FIGS. 4A and 4B, circumferential nozzle groove  76  is formed in outer surface  68  of nozzle body  28  below nozzle head  26 . Similarly, corresponding flange groove  78  is formed in inner surface  66  of the first cylindrical portion  60  of flange  42 . As seen in FIG. 4A, showing flange  42  secured to nozzle  18 , grooves  76  and  78  are aligned so that connector  70  may extend partially into each of grooves  76  and  78  to secure flange  42  in place. The depth of nozzle groove  76  from the outer surface of nozzle body  28  may be less than the diameter of connector  70 , as shown.  
         [0040]    The interaction of flange  42 , connector  70 , and nozzle  18  will now be described in greater detail with reference to FIGS. 2A through 5. As will be apparent from the following description flange  42  is generally either in a secured position or a released position with respect to nozzle  18 . Various views of connector  70  and flange  42  secured to nozzle body  28  are shown in FIGS. 2A, 3A,  4 A and  5 . The released position is illustrated in FIGS. 2B, 3B and  4 B.  
         [0041]    In order to connect flange  42  to nozzle  18 , connector  70  is positioned in flange  42  with fixed and movable ends  80  and  82  extending into hole  84  and slot  86 , respectively. Flange  42  is slipped over nozzle tip  30  and slid along nozzle body  28  towards nozzle head  26 . As flange  42  is slid along nozzle body  28 , movable end  82  is moved in direction  88 , which causes connector  70  to fully seat within flange groove  78 . As flange  42  is slid further onto nozzle body  28 , movable end is held in direction  88  so that flange  42  can be slid over nozzle body  28 . When top end  54  of first cylindrical portion  60  abuts shoulder  56  on nozzle head  26  flange groove  78  and nozzle groove  76  are aligned. When the two grooves are aligned, movable end  82  is released causing connector  70  to partially seat within nozzle groove  76 . As a result, connector  70  simultaneously is engaged with both nozzle groove  76  and flange groove  78  intersecting inner surface  66  and outer surface  68  and thereby secures the flange to nozzle body  28 . Nozzle  18  and flange  42  can then be mounted in, or removed from, mold plate  32  as a unit.  
         [0042]    Flange  42  may be released from nozzle body  28  by pushing on movable end  82  of connector  70  in the direction of arrow  88 , thereby retracting connector  70  out of nozzle groove  76  and fully into flange groove  78 . While movable end  82  is held in the direction of arrow  88 , flange  42  is able to freely slide along nozzle body  28  and can be removed.  
         [0043]    As will be apparent to those skilled in the art in light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the claimed scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.  
         [0044]    While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.