Patent Publication Number: US-2012040043-A1

Title: Modular Manifold System

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to the injection molding field and more specifically to modular manifold systems. 
     BACKGROUND OF THE INVENTION 
     Traditional hot runner systems include among other things a manifold housed between a manifold plate and a backing plate. A sprue bushing is mounted to the manifold and is the interface between the machine nozzle and the manifold. The sprue bushing receives molten material from the machine nozzle and transfers it to the manifold. Nozzle assemblies are coupled to the opposite side of the manifold from where the sprue bushing is mounted. After the molten material is transferred from the sprue bushing to the manifold, it is then transferred to the nozzle assemblies and then to the mold cavities for producing parts. 
     The manufacturing of manifolds is costly and time consuming. For one piece manifolds, the manufacturing starts from a block of material, such as steel. The block of material is then machined down to its final configuration. Melt passages are machined into the manifolds by drilling and heater grooves are milled on at least one outer surface of the manifold. Heater elements are then installed in the heater grooves. Plugging of melt passages is also required. For two piece manifolds, grooves which form part of the melt passages are milled into the complementary halves. Thereafter, the halves are welded or bonded together such that the grooves define melt passages. Heater grooves are milled on at least one outer surface of the manifold. Heater elements are then installed in the heater grooves. 
     Once machined as described above, the completed manifold is only useable in its final configuration and is not reconfigurable. The problems with these traditional manifolds are that they are labor intensive to machine, expensive, not reconfigurable, have manufacturing long lead times, and require a significant amount of material such as steel. 
     Modular manifold systems have been introduced that overcome some of the disadvantages and problems associated with traditional manifold systems. However, even modular manifold systems are not without disadvantages and problems. For example, the positioning of drops is critical for efficiency. Unfortunately, modular manifold systems are not easily aligned because there are many connection points with the potential for variation in alignment. 
     The following is directed to overcoming one or more of the disadvantages or problems set forth above. 
     SUMMARY OF THE INVENTION 
     The invention is set forth and characterized in the main claim(s), while the dependent claims describe other characteristics of the invention. 
     In one aspect of the present invention there is a modular manifold system  10  for an injection molding system having a distributor for receiving molten material from a source, at least one melt tube in fluid communication with the distributor and at least one drop block, at least one nozzle assembly in fluid communication with the drop block, wherein the at least one melt tube is not directly heated by a heater. 
     In another aspect of the invention, there is a modular manifold system for an injection molding system having a distributor for receiving molten material from a source, at least one melt tube in fluid communication with the distributor and at least one nozzle assembly, and an insulator configured to the melt tube. 
     In yet another aspect of the invention, there is a modular manifold system for an injection molding system having a distributor for receiving molten material from a source, at least one drop block in fluid communication with the distributor and at least one nozzle assembly in fluid communication with the drop block. 
     In still another aspect of the invention, there is a method for aligning a modular manifold system prior to assembly in a mold including the steps of placing the modular manifold system partially assembled between a plurality of plates, applying a compressive force to the modular manifold system via the plurality of plates, and securing the modular manifold system as it is positioned under the compressive force. 
     In yet still another aspect of the invention, there is a method for aligning a modular manifold system prior to assembly between a manifold plate and a backing plate including the steps of placing a center insulator into a centering bore in a bottom plate, placing a flange retainer onto a second end of a melt tube, threading the second end of the melt tube to a drop block, partially tightening screws of the flange retainer, assembling a backup pad on the drop blocks, placing the modular manifold system onto the bottom plate, centering the modular manifold system on the center insulator, placing the top plate on the backup pad of the modular manifold system, and tightening screws to compress the modular manifold system, and fully tightening the screws of the flange retainers. 
     These and other aspects and features of non-limiting embodiments of the present invention will now become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments of the invention in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and its embodiments will be more fully appreciated by reference to the following detailed description of illustrative (non-limiting) embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a modular manifold system according to a first non-limiting embodiment. 
         FIG. 2  is an isometric view of the modular manifold system according to another non-limiting embodiment. 
         FIG. 3  is a cross-sectional view of a portion of the modular manifold system according to still another non-limiting embodiment. 
         FIG. 4  is a cross-sectional view of a portion of the modular manifold system according to yet another non-limiting embodiment. 
         FIG. 5  is an isometric view of a drop block and insert of the modular manifold system shown in  FIG. 2 . 
         FIG. 6  is an exploded view of an alignment device for the modular manifold system. 
         FIG. 7  is an exploded view of the alignment device utilizing wedges with the modular manifold system. 
         FIGS. 8A &amp; 8B  are cross-sectional views of a portion of the modular manifold system having an adapter incorporated therein. 
     
    
    
     The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted. 
     DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENT(S) 
     Referring now to the drawings and initially to  FIG. 1  which is a non-limiting and example embodiment, a modular manifold system  10  is shown housed between a manifold plate  12  and a backing plate  14 . The modular manifold system  10  includes a sprue bushing  16  having an inlet end  32  and a flow passage  22  in fluid communication with a machine nozzle (not shown) of an injection molding machine. The sprue bushing  16  is heated with a heater  56 . In an alternative embodiment, the sprue bushing  16  is not heated by the heater  56 . An exit end  30  of the sprue bushing  16  is operatively attached to an inlet end  34  of a distributor  18 . In one embodiment, the sprue bushing  16  is operatively mounted to the distributor  18  via sprue bushing screws  64 . In an alternative embodiment, the sprue bushing  16  and distributor  18  are integral. The flow passage  22  of the sprue bushing  16  is in fluid communication with flow passages  24  of the distributor  18 . The distributor  18  is heated by one or more heater  20  and is located with a center insulator  90 . Exit ends  36  of the distributor  18  are also operatively attached to first ends  38  of the melt tubes  26 . In one embodiment, the first ends  38  of the melt tubes  26  are seated against the distributor  18  and secured thereto with flange retainers  66  and screws  68 . Shoulders  70  of the melt tubes  26  are trapped or secured between the flange retainers  66  and the distributor  18  via the screws  68 . The flow passages  24  of the distributor  18  are in fluid communication with flow passages  28  of the melt tubes  26 . The melt tubes  26  may or may not be heated by a heater (not shown). The melt tubes  26  without heaters may or may not contain insulation. The insulation may be any insulative material such as a silica blanket for example. In the embodiment not utilizing a heater or insulation, the material used for the melt tubes  26  is sufficiently conductive to maintain the molten material in its molten state along the length of the flow passages  28  of the melt tubes  26 , thereby eliminating the need for a heater, thermally conductive sleeve, or insulation. In another embodiment, the melt tubes  26  contain both a heater and insulator. The melt tubes  26  may be made from steel or a copper based alloy for example. It is analytically possible to determine at which lengths of the melt tubes  26  not having heaters require insulative material around the circumference of the melt tubes  26  to maintain the molten material in a molten state. It is also analytically possible to determine at which lengths of the melt tubes  25  heaters would be required in lieu of the insulative material to maintain the molten material in a molten state along the length of the flow passages  28  of the melt tubes  26 . Second ends  40  of the melt tubes  26  are operatively attached to inlet ends  42  of drop blocks  44 . In one embodiment, the second ends  40  of the melt tubes  26  are threaded to the inlet ends  42  of the drop blocks  44 . The flow passages  28  of the melt tubes  26  are in fluid communication with flow passages  52  of the drop blocks  44 . Outlet ends  46  of the drop blocks  44  are in sliding engagement with first ends  50  of nozzle assemblies  48 . In one example, the nozzle assemblies  48  are held in sliding engagement with the drop block  44  via a spring pack  72 . The spring pack  72  provides sufficient seal-off force to preclude leakage between the nozzle assemblies  48  and the drop blocks  44 . In other embodiments, the nozzle assemblies  48  may be fixed to the drop blocks  44  via screws or other securing devices (not shown). The drop blocks  44  are heated by heaters  58 . The heaters  58  may be film heaters, plasma spray heaters, coil heaters, cartridge heaters, or other known heating devices. The flow passages  52  of the drop blocks  44  are in fluid communication with flow passages  54  of the nozzle assemblies  48 . The nozzle assemblies  48  are heated by heaters  60 . The flow passages  54  of the nozzle assemblies  48  are in fluid communication with a mold cavity  62 . 
     The flow of molten material to the mold cavities  62  is controlled by valve stems  76 . To preclude or cease the flow of molten material to the mold cavities  62 , tips  78  of the valve stems  76  plug or block the gate areas. To allow the flow of molten material to the mold cavities  62 , the valve stems  76  are retracted such that the tips  78  of the valve stems  76  do not plug or block the gate areas. 
     Turning now to another embodiment of the modular manifold system  10  as shown in  FIG. 2 , the sprue bushing  16  is operatively mounted to the distributor  18  via sprue bushing screws  64 . The first ends  38  of the melt tubes  26  are threaded to the exit ends  36  of the distributor  18 . The second ends  40  of the melt tubes  26  are seated against the drop blocks  44  and secured thereto with the flange retainers  66  and screws  68 . The shoulders  70  of the melt tubes  26  are trapped or secured between the flange retainers  66  and the drop blocks  44  via the screws  68 . The nozzle assemblies  48  are operatively attached to the drop blocks  44 . In this embodiment, the flange retainers  66  are assembled to the drop blocks  44  and the melt tubes  26  are threaded to the distributor  18  whereas the embodiment shown in  FIG. 1  has the flange retainers  66  assembled to the distributor  18  and the melt tubes  26  threaded to the drop blocks  44 . 
     Turning now to still another embodiment of the modular manifold system  10  as shown in  FIG. 3 , in this embodiment the locations of the drops, including but not limited to actuators  82 , the drop blocks  44 , stem guides  74  (if used), and nozzle assemblies  48  may be fixed. In one example, the drops are removably secured to a manifold plate  84 . This fixed drop embodiment allows for the utilization of screw-in type nozzle assemblies  48 . For example, upper ends  86  of the nozzle assemblies  48  are threaded to and received by complementary threaded ends  88  of the drop blocks  44 . This facilitates, among other things, removal and replacement of the nozzle assemblies  48  in the field without disassembling the manifold plate  84  and the backing plate (not shown). The sprue bushing  16  is operatively mounted to the distributor  18  via sprue bushing screws  64 . The first ends  38  of the melt tubes  26  are slidably engaged to the exit ends  36  of the distributor  18 . In the cold condition, the flow passages  24  of the distributor  18  are slightly offset from the flow passages  28  of the melt tubes  26 . After heat up and in the operating condition as shown in  FIG. 3 , the flow passages  24  of the distributor  18  align with the flow passages  28  of the melt tubes  26 . The first ends  38  of the melt tubes  26  are held in sliding engagement to the exit ends  36  of the distributor  18  by the center insulator  90  and spring  92 . In an alternative embodiment, a ceramic disc (not shown) may be used between the spring  92  and the melt tubes  26 . The second ends  40  of the melt tubes  26  are seated against the drop blocks  44  and secured thereto with the flange retainers  66  and retaining rings  94 . The shoulders  70  of the melt tubes  26  are trapped or secured between the flange retainers  66  and the drop blocks  44  via the retaining ring  94 . 
     In an alternative embodiment shown in  FIG. 4 , the modular manifold system  10  does not utilize the melt tubes  26  previously described. The drop blocks  44  are operatively attached to the distributor  18  without the melt tubes  26  located therebetween. In one embodiment, block screws  80  are used to attach the drop blocks  44  to the distributor  18 . This embodiment accommodates small pitch designs. 
     Referring now to  FIG. 5 , the drop block  44  is shown having a stem guide  74 . The stem guide  74  may be implemented in any of the embodiments described herein. The stem guide  74  guides the valve stem  76  and precludes flow between it and the valve stem  76 . In one embodiment, the stem guide  74  is made from a material that is different from the material of the drop block  44 . For example, to reduce wear, the stem guide  74  may be made from a wear resistant material such as hardened tool steel or ceramic for example. In another example, to reduce heat transfer from the nozzle assemblies  48  to the valve stem  76 , the stem guide  74  may be made from a low thermally conductive material such as ceramics and titanium for example. In yet another example, to reduce galling, the stem guide  74  may be made from a material having a certain hardness criteria such as hardened tool steel or ceramic for example. In still another example, thermal transfer between stem guide  74  and the drop block  44  is reduced by limiting the contact surfaces between the two parts. In another embodiment, the drop block  44  does not have the stem guide  74 . 
     During operation of the embodiments shown in  FIGS. 1-3 , the machine nozzle injects molten material into the modular manifold system  10  through the flow passage  22  of the sprue bushing  16  which leads to the flow passages  24  of the distributor  18 . The molten material is then transferred to the flow passages  28  of the melt tubes  26  and onto the flow passages  52  of the drop blocks  44 . The molten material is then transferred to the flow passages  54  of the nozzle assemblies  48  and ultimately into the mold cavities  62  to produce parts after cooling and solidification of the molten material. 
     During operation of the embodiment shown in  FIG. 4 , the machine nozzle injects molten material into the modular manifold system  10  through the flow passage  22  of the sprue bushing  16  which leads to the flow passages  24  of the distributor  18 . Then, the molten material is transferred to the flow passages  52  of the drop blocks  44  and then onto the flow passages  54  of the nozzle assemblies  48  and ultimately into the mold cavities  62  to produce parts after cooling and solidification of the molten material. 
     In the embodiments disclosed herein, the distributor  18  may be manufactured from common blanks. In other words, the blanks are not unique to each design and may be standard for all designs. For example, the same blank may be used for a two-drop or four-drop system. Further, the same blank may be used for a variety of pitch dimensions. The melt tubes  26  may be inventoried at one length and cut to length after an order is received. Various inventories for the melt tubes  26  may be kept because the melt flow channel sizes of the melt tubes  26  as measured from the outside diameter vary (for example, 0.250 of an inch, 0.350 of an inch, 0.500 of an inch, etc.). After an order is received for a certain diameter, the melt tubes  26  having that diameter may be cut to length and at least one of the ends threaded depending on the application. The drop blocks  44  may be mass produced and inventoried to the various melt flow channel sizes of the drop blocks  44 . If stem guides  74  are used with the drop blocks  44 , the stem guides  74  may also be mass produced and inventoried to the various melt flow channel sizes of the stem guides  74 . With regard to the drop blocks  44 , additional inventories may be kept containing valve gate style nozzle assemblies  48  and hot tip style nozzle assemblies. 
     As mentioned above, the melt tubes  26  may contain heaters. In one embodiment, heaters are applied directly to the components, including the melt tubes  26 , of the modular manifold system  10  with a plasma spray process. Prior to plasma spraying the components, the outside surfaces of the components are sandblasted. A dielectric layer is deposited onto the outside surfaces of the components with plasma spray or more specifically atmospheric plasma spray (APS). One type of dielectric material is aluminum oxide but other materials having similar dielectric properties could be used. A resistive layer is deposited over the dielectric layer with APS. The resistive layer is made primarily from nichrome (80% nickel and 29% chromium) along with other materials, for example. Thereafter, a laser is used to etch away certain portions of the resistive layer. The remaining resistive layer serves as the heating circuit. Ends of the heating circuit or connector points are masked with for example laser cut foil. A dielectric layer is deposited onto the areas that have been removed by the laser and the remaining resistive layer with APS. The masking is removed from the ends of the heating circuit or the connector points. Power leads are connected to the ends of the heating circuit or the connector points. Thereafter, a moisture barrier layer is deposited over the last applied dielectric layer and ends of the heating circuit or the connector points. The moisture barrier is made primarily from zirconia, zirconium dioxide, or aluminum oxide, all of which may be combined with other materials, for example. 
     The previously described modular manifold systems  10  may be reconfigurable and provides for reusability of components for different applications. In one reconfigurable embodiment, the lengths of the melt tubes  26  are modified to accommodate different pitches or applications. The sprue bushing  16 , distributor  18 , drop blocks  44 , and nozzle assemblies  48  are reusable whereas the melt tubes  26  are replaced from one pitch or application to another pitch or application. Typically, the melt tubes  26  will be swapped out with melt tubes  26  having different lengths or cut to smaller lengths to fit the new application. In another embodiment, the modular manifold system  10  may have melt tubes  26  with different lengths and/or diameters. In another embodiment, the configuration of the distributor  18  may be manufactured to accommodate various pitch applications. 
     The distributor  18 , melt tubes  26 , and drop blocks  44  previously described with regard to the modular manifold systems  10  may be aligned prior to assembly to the nozzle assemblies  48  and plates (not shown). Referring now to  FIG. 6 , an alignment device  96  includes a top plate  98 , a bottom plate  100 , and screws  102 . The top plate  98  may be ground flat. The bottom plate  100  may be ground flat and contains a centering bore  104  for receiving the center insulator  90  of the modular manifold system  10 . The alignment device  96  may be used to pre-align a wide range of pitch spacing applications including the various embodiments described herein. In the following alignment process, the embodiment of the modular manifold system  10  described in  FIG. 1  will be referenced. The alignment process includes the following steps: 1) the center insulator  90  is placed into the centering bore  104  of the bottom plate  100 ; 2) the flange retainers  66  are slipped onto the second ends  40  of the melt tubes  26  and slid down to the shoulders  70  proximate the first ends  38  of the melt tubes  26 ; 3) the second ends  40  of the melt tubes  26  are threaded onto the inlet ends  42  of drop blocks  44 ; 4) the first ends  38  of the melt tubes  26  are seated against the distributor  18  and the screws  68  are partially threaded thereby trapping the shoulders  70  of the melt tubes  26  between the flange retainers  66  and the distributor  18 ; 5) backup pads  106  are assembled to the drop blocks  44 ; 6) the partially assembled modular manifold system  10  is then placed onto the bottom plate  100  and centered on the center insulator  90 ; 7) the top plate  98  is placed onto the top of the partially assembled modular manifold system  10 ; 8) the screws  102  are tightened down to compress the partially assembled modular manifold system  10  such that a 0.030 mm shim cannot pass under the drop block  44 ; and 9) the screws  68  of the flange retainers  66  are fully tourqued to a predetermined load to ensure sealing. This process and the alignment device  96  provide planar alignment of the modular manifold system  10  and orientate the drop blocks  44  with respect to a mold (not shown). 
     Referring now to  FIG. 7 , in certain applications, it may be desirable to angle the drops with respect to a vertical axis  112  of the modular manifold system  10 . To vary the angle of the drops, the drop blocks  44  are angled with respect to the vertical axis  112 . Wedges  110  may be used between the drop blocks  44  and the bottom plate  100  to place the drop blocks  44  at the desired angle. The wedges  110  have a bottom surface  114  which is substantially flat and parallel with a horizontal axis  108  of the bottom plate  100 . The wedges  110  have a top surface  116  which is at an angle A with respect to the bottom surface  114 . When the wedges  110  are placed between the drop blocks  44  and the bottom plate  100 , the drop blocks  44  are placed onto the wedges  110  and thus positioned at the angle A, which is consistent with the desired angle of the drops. When the wedges  110  are used with the modular manifold systems  10 , the alignment process includes the following steps: 1) the center insulator  90  is placed into the centering bore  104  of the bottom plate  100 ; 2) the flange retainers  66  are slipped onto the second ends  40  of the melt tubes  26  and slid down to the shoulders  70  proximate the first ends  38  of the melt tubes  26 ; 3) the second ends  40  of the melt tubes  26  are threaded onto the inlet ends  42  of drop blocks  44 ; 4) the wedges  110  are placed where the drop blocks  44  would come in contact with the bottom plate  100 ; 5) the first ends  38  of the melt tubes  26  are seated against the distributor  18  and the screws  68  are partially threaded thereby trapping the shoulders  70  of the melt tubes  26  between the flange retainers  66  and the distributor  18 ; 6) the backup pads  106  are assembled to the drop blocks  44 ; 7) the partially assembled modular manifold system  10  is then centered on the center insulator  90  and placed on the bottom plate  100  such that the drop blocks  44  are seated on the wedges  110 ; 8) complementary wedges  118  having a complementary angle A′ to the angle A of the wedges  110  are secured to the top plate  98  where the backup pads  106  would come in contact with the top plate  98 ; 9) the top plate  98  is placed onto the top of the partially assembled modular manifold system  10 ; 8) the screws  102  are tightened down to compress the partially assembled modular manifold system  10  such that a 0.030 mm shim cannot pass under the drop block  44 ; and 9) the screws  68  of the flange retainers  66  are fully tourqued to a predetermined load to ensure sealing. This process and the alignment device  96  provide planar alignment of the distributor  18  and angular alignment of the drop blocks  44  with respect to a mold (not shown). 
     Referring now to  FIGS. 8A &amp; 8B , adapters  120  may be used with the melt tubes  26 . The adapters  120  provide for mounting the melt tubes  26  and the drop blocks  44  to position the melt tubes  26  at an upward or downward angle. The adapters  120  have surfaces  124  for mounting substantially flush and parallel with the exit ends  36  of the distributor  18 . The adapters  120  have bores  128  so that adapter screws  126  may be used to secure the adapters  120  to the distributor  18 . Referring now in combination to  FIGS. 6 ,  8 A, and  8 B, the process of assembling the modular manifold system  10  having the adapters  120  includes the following steps: 1) the flange retainers  66  are slipped onto the second ends  40  of the melt tubes  26  and slid down to the shoulders  70  proximate the first ends  38  of the melt tubes  26 ; 2) the second ends  40  of the melt tubes  26  are threaded onto the inlet ends  42  of drop blocks  44 ; 3) the adapters  120  are attached to the distributor  18  with the adapter screws  126 ; 4) the first ends  38  of the melt tubes  26  are seated against the adapters  120  and the screws  68  are fully tourqued to a predetermined load to ensure sealing, thereby trapping the shoulders  70  of the melt tubes  26  between the flange retainers  66  and the adapters  120 ; and 5) the backup pads  106  are assembled to the drop blocks  44 . 
     The modular manifold systems  10  described above referred to a valve gate system. In an alternative embodiment, the modular manifold system  10  may also be a hot tip system. In the hot type system embodiment, there is not actuation system (e.g, piston, cylinder, seals, etc.), valve stem, or valve stem hole in the drop block  44 . 
     It is noted that the foregoing has outlined some of the more pertinent non-limiting embodiments. These embodiments may be used for many applications. Thus, although the description is made for particular arrangements and methods, the intent and concept of the embodiments are suitable and applicable to other arrangements and applications. It will be clear to those skilled in the art that modifications to the disclosed non-limiting embodiments can be effected. The described non-limiting embodiments ought to be construed to be merely illustrative of some of the more prominent features and applications. Other beneficial results can be realized by applying the disclosed embodiments in a different manner or modifying them in ways known to those familiar with the art. The mixing and matching of features, elements, and/or functions between various non-limiting embodiments are expressly contemplated herein, unless described otherwise, above.