Patent Publication Number: US-8529820-B1

Title: Adjustable melt rotation positioning device and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 11/434,806 filed on May 17, 2006, now U.S. Pat. No. 7,780,895 which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 60/681,442, filed on May 17, 2005, both of which applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     This invention relates to methods and apparatus for adjustably controlling the repositioning of non-homogeneous melt conditions across the stream of a laminar flowing fluid to a desirable circumferential position. The invention is particularly useful in cold-runner or hot-runner molding systems that flow a stream of laminar flowing material, such as molten plastic, into a single or multiple cavity mold through at least one runner flowing a non-homogeneous melt. 
     In multi-cavity molds, it is important for the material to be uniformly delivered to each of the cavities. However, significant shear and thermal variations are developed in a polymer melt as it flows through a runner, creating non-homogeneous melt conditions that may be asymmetrical or symmetrical across the flow stream. Such variations may result in cavity to cavity mold filling imbalances of more than 30%. These same melt variations may also cause problems while filling a given cavity within multi or single cavity molds. For example, such melt variations may create unanticipated filling patterns within a part forming cavity and affect the physical attributes of the molded part, such as shrinkage or warpage. 
     When molding parts using multi-cavity molds, it is standard practice to geometrically balance the runner system in order to help provide the required mold filling consistency. In geometrically balanced runners, each cavity is fed by runner sections having the same lengths, cross-sectional size and shape. The same concept of a geometrically balanced runner system may also be applied to multiple runner branches that may be feeding a single part at multiple locations. However, despite the geometrical balance, it has been observed that mold filling using this balanced runner design still results in imbalance. Specifically, as described in U.S. Pat. No. 6,077,470 to Beaumont and U.S. Pat. No. 6,503,438 to Beaumont et al., parts formed in the cavities on the inside branches are often of a different size or weight than are the parts formed in the other cavities. 
     In particular, it has been found that even with a geometrically balanced runner system, a flow-induced cavity filling imbalance exists. Several factors act to create this imbalance, including a non-symmetrical shear distribution developed within a laminar flowing material as it travels through the runner system. Flow imbalance can also be created by a non-symmetrical temperature distribution developed across the melt stream. Both of these non-symmetrical conditions can result in variations in the viscosity across the stream of flowing material and, in some cases, in its structure. 
     Various manufacturing processes and apparatus use laminar flowing material flowing through one or more tools, such as dies or molds, in the formation of products. These tools have various part forming geometries used to shape the laminar flowing materials into desired products. As used hereinafter, the term “tool” includes all of the components within the body of an entire mold or die used to produce one or more products. Normally, tools of these types are constructed of high strength materials, such as tool steels or aluminum alloys having a very high compression yield strength, so as to withstand the pressure which forces the laminar flowing material through flow paths within the tools. These flow paths are commonly referred to by terms such as channels or runners, depending on the actual manufacturing process or tool being used. The terms “runner” and “runner system” will be used hereinafter to mean a flow path through a tool for laminar flowing material. 
     Typical cross sectional shapes of runners include, but are not limited to, full round, half round, trapezoidal, modified trapezoidal or parabolic, and rectangular. Runners maybe solidifying or non-solidifying. For example, in thermoplastic injection molding processes, laminar flowing material in cold runners solidifies during the manufacture of products and is ejected from the tool during each cycle of the process. Whereas, hot runners are typically machined inside a block of high strength material and heated within the block so that the laminar flowing material within the hot runners remains fluid and is not ejected. Some tools may contain both hot runners and cold runners. 
     Manufacturing processes using tools and runner systems of the types described above include, but are not limited to, injection molding, transfer molding, blow molding and extrusion molding. The materials typically used in these processes include thermoplastics, thermosets, powdered metal and ceramics employing laminar flowing carriers, such as polymers. While this invention is useful for manufacturing methods and for apparatus which use the materials described above, this invention can be used to correct imbalances occurring in any tool in which imbalances occur in runners carrying a fluid exhibiting laminar flow and having a viscosity which is affected by shear rate (as with a non-Newtonian fluid) and/or by temperature, that is a fluid exhibiting variations in its characteristics as a result of variations in shear or flow velocity across the cross section of a runner. 
     Molding processes produce products by flowing laminar flowing material from a material source and through a runner system in a tool to an area or areas where the material is used to form the product. Molding processes include injection and transfer molding, in which laminar flowing material is injected under high pressure into a tool and through the runner system to a cavity or cavities in the tool (called a mold). The mold may have a single parting plane which separates two mold halves for forming molded items, or the mold may be a stack mold which has more than one parting plane, each separating a pair of mold halves. The material flows in concentric laminates through runners of whichever shape is used for a tool by following the center of the path of the runners. 
     Another manufacturing process using laminar flowing materials flowing in a runner system through a tool is extrusion blow molding. In the extrusion blow molding process, laminar flowing material is fed from a material source through a tool which includes a single runner or a branched runner system. After the material is fed through the runner system, it passes around a normally torpedo shaped insert near the end of the runner system which is used to form the solid stream of laminar flowing material into a tube, or profile, of material exiting the die. This tube of material is normally referred to as a parison. As the parison continues to lengthen to its desired length, it is clamped between two halves of a tool closing around it, and the tool then normally pinches off the bottom of the parison. Next, air is injected inside the tube of material, causing the material to expand against part forming walls of the tool. The material inside the tool is then cooled, solidifies, and is ejected after the tool is opened at the end of each production cycle. The tool then returns into position to grab another parison. 
     Yet another process using laminar flowing material flowing in a runner system through a tool is extrusion. In extrusion processes the laminar flowing material is normally, continuously fed from a material source through a die having a single runner or a branched runner system to be delivered to a part forming geometry which shapes the material as it exits at the end of the die. The extrusion process is normally referred to as a steady-state process and produces continuous shapes, or profiles, such as pipes or the coatings on electrical wires. As the laminar flowing material exits the part forming die, the material is normally drawn through a coolant, such as water, where it takes on its final shape as it solidifies. 
     Regardless of process and the type of molding system used, as a laminar flowing material flows through a runner, material near the perimeter of the runner experiences high shear conditions, whereas the material near the center experiences low shear conditions. These shear conditions are developed from the velocity of the flowing material relative to the stationary boundary of the flow channel and the relative velocity of the laminates of material flowing through the channel.  FIG. 1  illustrates a characteristic shear rate distribution across the diameter “d” of a runner, where the magnitude of the shear rate is shown on the horizontal axis and the diameter is shown on the vertical axis. Shear rate is normally at or near zero at the outermost perimeter of a runner, is at its maximum level near the perimeter of the runner, and is then reduced to a level at or near zero in the center of the runner. As shown in the cross-section of runner  20  in  FIG. 2 , a predominantly high shear region  22  forms around the inner periphery of the runner while a predominantly low shear region  24  forms around the center. 
     Material in the high shear region  22  gains heat from friction caused by the relative velocity of the laminates as the laminar flowing material flows through the runner. This heat, and the effects of the shear on the non-Newtonian characteristics of polymers and other laminar flowing materials, normally causes the high sheared material near the perimeter of the runner to have a lower viscosity. Because of this lowered viscosity, fluid in this region flows more readily than the material in the center of the runner. 
     The effects on the flow of laminar flowing material and products produced by this material are dominated by the contrasts of the characteristics between the high sheared region  22  and the low sheared region  24 . Initially, the high and low sheared regions of material are significantly balanced about bisecting planes  26  and  28 . Thus, they are “significantly balanced” from side-to-side or across a plane at a particular location in a runner. This results in a variation of a symmetrical non-homogeneous melt condition being developed across the flow channel. 
     Although flow may be initially balanced as shown in  FIG. 2 , non-balanced conditions develop in a runner system when a first runner section, such as runner  20 , branches in two or more directions. Because flow is laminar, when a branch in the runner occurs, the high sheared, hotter material along the perimeter remains in its relative outer position. However, the inner material is split and is now positioned on the opposite side of the flow channel from the high sheared hotter material. This creates a side-to-side variation between upcoming side-to-side branching runners, or in a mold cavity, where the high sheared hotter material will flow to one side and the low sheared cooler material will flow to the other side. This variation will be described briefly with respect to  FIG. 3 . 
     Runner  20  may be a sprue, which is a specially designed runner that conveys material from a material source such as an injection molding machine. Alternatively, runner  20  may be a runner at a selected location in a tool. Cross-section AA in  FIG. 3A  shows the initial symmetrical conditions about the planes  26  and  28 , the same as are depicted in  FIG. 2 . As runner  20  branches in two directions, each branch  30 ,  32  receives equal portions of high and low sheared material. The high and low sheared material on the left side of runner  20  flows to the left branching runner  30 , and the high and low sheared material on the right side of runner  20  flows to the right branching runner  32 . The two halves of material from runner  20  will reform to an approximate shape of the branch runners  30  and  32 . Assuming the material is flowing from top to bottom of runner  20 , the high and low sheared material from runner  20  will distribute itself in runners  30  and  32  in the approximate positions and shapes illustrated in section BB of runner  32 , which are shown in  FIG. 3B . 
     As can be seen in  FIG. 3B , due to the laminar flowing conditions of the material, the flow of material in runner  20  causes most of the high sheared material near the periphery of runner  20  to remain as high sheared material  31  on the top side of both of the branching runners  30  and  32 . The low sheared material at the center of runner  20  flows to the bottom of the branch runners  30  and  32  and is shown as low sheared material  33 . The distribution of the high sheared material  31  and the low sheared material  33  in runner  32  in  FIG. 3B  is symmetrical about plane  34 . Thus, the distribution remains significantly balanced side-to-side across plane  34 , which bisects the length of runner  32 , as well as bisects runner  20 . However, the distribution of high sheared material  31  and the low sheared material  33  is now unbalanced from side-to-side across horizontal plane  36 , which bisects runner  32  and is perpendicular to plane  34 . The results is a non-homogeneous melt condition which is symmetrical across plane  34  and non-symmetrical across plane  36 . 
     Referring once again back to  FIG. 3 , the branch runner  32  itself branches in two directions through runner  38 , which extends toward the top of  FIG. 3 , and runner  40 , which extends toward the bottom of  FIG. 3 . Due to the laminar nature of the material, most or all of the high sheared material  31  at the top of runner  32 , see  FIG. 3B , flows into runner  38  and primarily or solely low sheared material  33  flows into runner  40 .  FIG. 3C  shows the high sheared material  31  at Section CC of runner  38  and  FIG. 3D  shows the low sheared material  33  at Section DD of runner  40 . The actual distribution of the high sheared material  31  across the cross section of runner  32  in any tool will determine how much, if any, of the high sheared material flows in runner  40  and, thus, whether most or all of the high sheared material  31  flows in runner  38 . 
     Thus, laminar flow through successive branches of a runner system has the effect of shifting the flow distribution to a symmetrically unbalanced state. This imbalance leads to problems with flow-induced cavity fill. The imbalance further results in product differences and/or differences in material from one cavity to the next in a multi-cavity mold, such as differences in viscosity, temperature, cooling rate, shrinkage, and warpage. Additionally, the imbalance increases clamp tonnage, i.e., the force at which mold portions are pressed together, necessary for the mold to absorb pressure surges caused by the imbalance and non-parallel mold filling. 
       FIGS. 3A-D  only consider the effect of the primary runner on the distribution. Other factors also affect the distribution of the flow, including those caused by the molding machine nozzle or the mold sprue.  FIG. 4A  shows the positioning of the high sheared laminates in a runner as a result of shear developed solely due to sprue or nozzle effect. Here, the high sheared material is distributed on the sprue side (top) of the primary runner  32  and then onto the top inner side of the branching secondary runner  38 ,  40  in a region  31 A. As a result, the high sheared laminates exiting the secondary branching  38 ,  40  have symmetry about an axis A as shown, which is at an angle relative to the vertical. 
       FIG. 4B  shows the positioning of the high sheared laminates in the runner solely as a result of shear caused by the flow through the primary runner and the branching runner. Thus,  FIG. 4B  corresponds to  FIG. 3C  and has a high shear laminate in a region  31 B that is axisymmetric as it travels along the primary runner until it branches off into the secondary runner  38 ,  40 . At that time, the high sheared material becomes positioned on the sprue side of the secondary runner, as shown, to have symmetry with horizontal axis B. 
       FIG. 4C  shows the resultant positioning of the high sheared laminates in the runner as a result of the combination of sprue and runner effects. This can be better visualized by  FIG. 4D , which shows the additive effect of the combination. In particular, there is an overlap region  31 A′B′ formed from overlapping portions of regions  31 A and  31 B, combined with remaining portions of regions  31 A and  31 B. The combination has a resultant axis of symmetry that is centered about axis C, located between axes A and B as shown. As a result, the material feeding a downstream side-to-side branching runner will receive asymmetric conditions, which will normally cause the high sheared material to feed the cavities on the sprue side of the secondary runner first. 
     Recently, there have been developed methods and apparatus to control a repositioning of the asymmetric conditions across the stream of a laminar flowing fluid to a desirable position. This repositioning, referred to in the art of plastics molding as melt rotation technology, has been accomplished through a wide variety of designs and methods as taught in U.S. Pat. No. 6,077,470 to Beaumont and U.S. Pat. No. 6,503,438 to Beaumont et al., both of which are hereby incorporated herein by reference in their entireties and currently marketed and licensed as incorporating Meltflipper® technology. These prior methods use laminar fluid rotation devices with fixed flow geometries to achieve a calculated repositioning or rotation of the laminar fluid stream. 
     Typical laminar fluid rotation devices are created by machining a desired geometry into a mold or manifold surface or into a steel insert to be fit into the mold or manifold. For example, as shown in  FIG. 5 , two mold insert halves  110 ,  120  are machined to form a transitional area between branching runners. This transitional area causes a predetermined flow geometry, achieving an elevation change and a circumferential repositioning of the laminar fluid flow. 
     Conventionally, a laminar fluid rotation device was designed to achieve a desired circumferential repositioning of the laminar fluid to improve mold cavity filling and melt distribution through management of flow-induced melt variations. Commonly, this means designing the runner system to achieve a desirable rotation at one or more runner intersections or inline within a runner to reposition the orientation of the laminar stream to achieve a desired distribution of material. This technology does not typically achieve a homogeneous distribution of fluid to each cavity, as may be done using a static mixer, and may not eliminate asymmetric flow conditions. Rather, the technology takes advantage of the laminar flow structure to manage the conditions at downstream branches and mold cavities through controlled rotation of the stratified laminar stream. 
     Various examples of conventional prior art fixed structure fluid rotation devices are shown in the cross-sectional views of  FIGS. 5A-C  taken along the centerline of first runner section  32 . These particular examples are formed from two machined mold insert halves  110  and  120 . Section  100  includes channeling formed in the lower mold half  110  that corresponds to an intersection of the first runner section  32  and second runner section  38 . 
     Although primary sections of runners  32  and  38  are commonly round in cross-section, for ease in manufacture of the molding insert halves and to facilitate ejection of the frozen runner in cold runner systems, portions of the runner in section  100  have been formed with a U-shaped cross-section, such as that shown in  FIGS. 5A-C . That is, the runners through the flow rotation device  100  have a flat upper surface as shown formed from a flat face of upper mold insert  120 . 
     A flow diverter section  115  is provided in the flow path to force the flow upwards to make an angular elevation change into a runner region  125  of the upper mold half  120 . At the end of the region  125 , the region transitions into second runner section  38 . This flow channel path of  FIG. 5A , which achieves a full elevation change, causes the asymmetrical fluid conditions to be rotated by roughly 90° (more realistically 80°) along the circumference of the flow channel, as more fully described in the above Beaumont patents. 
       FIGS. 5B-C  show different mold geometries that have been modified through remachining or other method to have the flow design changed to reflect a different resultant elevation change. This allows for a circumferential repositioning of the asymmetrical fluid conditions in the runner by lesser amounts. That is, by having different heights of the flow diverter sections  115 ′ and  115 ″, and thus reducing the elevation change, repositioning of the laminar fluid flow to lesser degrees can be achieved. To better illustrate how elevation change effects the circumferential repositioning of the laminar fluid,  FIG. 6  shows various elevational changes and approximate resultant degree of fluid flow rotation achieved. 
     Use of one or more correctly designed laminar fluid rotation devices in a runner system nearly always resulted in an improved fluid flow compared to runner flow without the laminar fluid rotation devices. However, due to the complex nature of the laminar flow and the interactive influences of the sprue or previous branches on the asymmetric melt conditions, a design that achieves an optimum positioning of the non-homogeneous conditions cannot always be determined without actual molding trials or use of expensive and time-consuming simulation methods. 
     Accordingly, current methods of melt rotation do not always result in a complete success in positioning of non-homogeneous melt conditions through melt rotation. In view of this, modification of the fluid rotation geometry was sometimes necessary to achieve a desired flow uniformity or control. For example, it may have been initially determined that a circumferential rotation of the flow stream by about 90° was desired and an initial fluid rotation device made as shown in  FIG. 5A . However, after experimentation through molding trials or the like, it is realized that this design does not achieve a desired repositioning of the melt conditions (for example, there may still be an imbalance causing one or more mold cavities to fill unevenly). As a result, it may be sometimes necessary to modify the mold components by removing the mold insert and modifying the fluid rotation geometry, typically by welding or remachining of an original geometry in the mold, mold insert or hot runner manifold to adjust the profile of the flow diverter section  115  to achieve a slight adjustment in repositioning of the fluid flow. For example, the mold insert may need to be machined to have a flow diverter section changed to that shown in either  FIG. 5B  or  5 C to achieve a desired melt rotation with an advantageous positioning of the symmetrical or non-symmetrical melt conditions. 
     SUMMARY 
     Although it is possible to attain a suitable fluid rotation device design using current methodologies, this process of trial and error modifying of fixed structure is both costly and time consuming. Redesign of the runner may require repeated machining of original insert geometry to achieve different elevation change and flow repositioning characteristics, which is costly. Redesign may include, for example, remachining of the mold, mold insert or hot runner manifold geometry by shaving down the flow inverter section  115  to a lower profile illustrated by inverters  115 ′ and  115 ″ in  FIGS. 5B and 5C . Making incremental machining changes and running numerous trial and error tests to optimize flow between each machining operation is time consuming and expensive. This is because disassembly of the mold and transportation of the mold inserts to a machining facility for repairs are necessary. 
     Existing fluid rotation technology is beneficial in providing desirable positioning of non-homogeneous melt conditions, but is capable of improvement. Current fixed-geometry fluid rotation devices, such as those marketed and licensed under the Beaumont Meltflipper® technology, are not adjusted while mounted insitu in the mold (i.e., at the site of the mold). Accordingly, unnecessary down time of the molding machine and remachining of the fluid rotation device geometry may be necessary to fine tune or optimize laminar flow for a particular runner system. Additionally, current fixed-geometry fluid rotation devices are not capable of accommodating changes to one or more molding parameters that would affect flow. Thus, each design or process change to the overall mold design may require a customized fluid rotation device design. 
     Accordingly, there is a need for improved apparatus and methods that can readily accommodate flow geometry redesign or complexity to achieve a more optimized output condition. Preferably, such apparatus and methods should be able to adjust flow geometry while the fluid rotation device remains insitu (at the site of the mold) and without requiring a completely new fluid rotation device mold or remachining of an existing mold or hot runner manifold. 
     There also is a need for improved methods and apparatus that enable quick and precise adjustment of the flow channel geometry to achieve desired fluid flow repositioning to correct imbalance conditions in a laminar flowing fluid moving in a hot or cold runner system or to otherwise adjust the non-homogeneous melt conditions to a desired state. 
     In exemplary embodiments, various mechanisms are provided that enable insitu adjustments of a laminar fluid rotation device flow diverter so that the degree of fluid flow repositioning in a runner system can be changed, without the need for extensive mold disassembly or retooling. Adjustments can be made manually or automatically and may include static or dynamic adjustments. Such adjustable fluid rotation devices are particularly useful in cold runner molding systems, but are also applicable to hot runner systems used in injection molding. Additionally, such devices could be useful in other processes, such as extrusion or extrusion blow molding. 
     In a first exemplary embodiment, an extendible pin is adjustably mounted in the flow channel near an intersection of a runner branch branching in one or more directions. By extending or retracting the height of the pin, the flow diverter geometry and elevation change can be modified to adjust laminar flow repositioning. 
     Adjustment of the pin position in the flow channel can be achieved through a manually operated actuator mechanism or a machine-driven actuator mechanism, or by simple replacement of the pin with pins of varying height. 
     In a second exemplary embodiment, a rotatable notched disk is provided as a flow diverter in the flow channel. The rotatable disk is adjusted to control the flow channel geometry and elevation change, allowing a change in the degree of fluid flow repositioning. 
     Adjustment of the rotatable disk can be achieved through a manually operated actuator mechanism or a machine-driven actuator mechanism. 
     In a third exemplary embodiment, an adjustable fluid rotation device is provided having a flow path that can be adjusted through rotation of one mold insert half relative to a mating mold insert half. In exemplary embodiments, the fluid rotation device can achieve circumferential repositioning of anywhere from 0 to up to +/−180° circumferential fluid flow rotation. Additionally, in the third embodiment, the adjustable fluid rotation device can be located anywhere along the runner, including at straight sections of the runner, by having an inline configuration. Thus, it is not necessary that the flow diverter be provided at a branching intersection. 
     In accordance with various exemplary embodiments, numerous methods of insitu flow diverter adjustment are provided that enable fine tuning of fluid flow circumferential repositioning. In certain embodiments, methods of adjustment are performed manually while the mold is inoperative. In other embodiments, methods of adjustment can be automated and controlled through open or closed loop control. In further embodiments, dynamic methods of adjustment are provided that change the fluid flow repositioning dynamically during a molding operation to create a flow path that can change over time to precisely control the flow front of the material flowing through a mold. 
     In accordance with various exemplary embodiments, methods and apparatus for insitu flow diverter adjustment are provided to reposition non-homogeneous melt conditions for a given purpose, such as control or influence of shrinkage, warpage and mechanical properties. The methods and apparatus may be used to fill a single or multiple cavity mold and may be provided anywhere in the runner. 
     In accordance with various embodiments, a method of adjusting the rotational positioning in the circumferential direction of multiple streams of laminar flowing fluid includes positioning the non-homogeneous melt conditions within the individual streams of laminar flowing material to a desirable position by the movement or replacement of a portion of the geometry defining the flow path and recombining the melt streams into a single melt stream to achieve a desirable distribution within the combined streams of laminar flowing fluid. 
     Those skilled in the art will realize that this invention is capable of embodiments that are different from those shown and that the details of the method and mold structure can be changed in various manners without departing from the scope of this invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and are not to restrict the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments will be described with reference to the drawings, wherein: 
         FIG. 1  is a conceptual, cross-sectional view of a runner depicting the development of shear along the flow path of the runner; 
         FIG. 2  is a conceptual, cross-sectional view of a runner depicting non-homogeneous symmetrical zones of high and low sheared flow distribution prior to branching; 
         FIG. 3  is an outside view of a branching runner that branches into a pair of branch runners; 
         FIG. 3A  is a conceptual, cross-sectional view depicting relative zones of high and low sheared laminar flow distribution in the runner prior to branching taken along line A-A; 
         FIG. 3B  is a conceptual, cross-sectional view depicting relative zones of high and low sheared laminar flow distribution in the runner taken along line B-B after branching from a first runner; 
         FIG. 3C  is a conceptual, cross-sectional view depicting relative zones of high and low sheared laminar flow distribution in the runner taken along line C-C taken after branching from a branching runner; 
         FIG. 3D  is a conceptual, cross-sectional view depicting relative zones of high and low sheared laminar flow distribution in the runner taken along line D-D after branching from a branching runner; 
         FIG. 4A  is an outside partial view of a branching runner showing high and low sheared laminar flow distribution due to shear developed in the sprue; 
         FIG. 4B  is an outside partial view of a branching runner showing high and low sheared laminar flow distribution due to shear developed in the primary runner during flow; 
         FIG. 4C  is an outside partial view of a branching runner showing the combined high and low sheared laminar flow distribution as a result of sprue and primary runner shear effects; 
         FIG. 4D  illustrates the additive nature of the two effects to form a resultant flow distribution; 
         FIG. 5  is a partial perspective view of a branching runner of a mold showing a typical fluid rotation device flow diverter; 
         FIGS. 5A-C  are partial cross-sectional views of three different fixed-configuration flow diverter mold inserts useful in a branching runner similar to that shown in  FIG. 5 ; 
         FIG. 6  illustrates the effect that progressive elevation changes have on the repositioning of the high and low sheared laminar flow distribution; 
         FIGS. 7A-C  are partial cross-sectional views of a first exemplary fluid rotation device having a linearly adjustable flow diverter section shown in three distinct adjustment configurations; 
         FIG. 8  is a top view of  FIGS. 7A-C  showing mold details of a lower mold half; 
         FIG. 9  is a cross-sectional view of an exemplary adjustable fluid rotation device having an adjustment actuator mechanism that provides linear travel adjustment to a flow diverter using a fulcrum lever; 
         FIGS. 10A-B  are cross-sectional views of a second exemplary fluid rotation device having a rotatably adjustable flow diverter section shown in two distinct adjustment configurations; 
         FIG. 11  is a cross-sectional view of a first exemplary actuator mechanism for a fluid rotation device having a rotatably adjustable fluid diverter section that uses a drive motor and automatic feedback control; 
         FIG. 12  is a cross-sectional view of a second exemplary actuator mechanism for a fluid rotation device having a rotatably adjustable fluid diverter section that uses a linearly traveling rack and pinion system as an adjustable actuator mechanism; 
         FIGS. 13-14  are cross-sectional views of third and fourth exemplary actuator mechanisms for a fluid rotation device having a rotatably adjustable flow diverter section that uses a threaded positioning screw and a cam element as an adjuster mechanism; 
         FIG. 15  is a cross-sectional view of a fifth exemplary actuator mechanism for a fluid rotation device having a rotatably adjustable flow diverter section that uses a threaded positioning screw and a fulcrum lever; 
         FIG. 16  is a top view of another embodiment of an adjustable melt flow diverter device; 
         FIGS. 17-18  are cross-sectional views of the flow diverter device of  FIG. 16  in first and second positions; 
         FIG. 19  is a top view of a further embodiment of a flow diverter device; 
         FIG. 20  is a cross-sectional view of the flow diverter device of  FIG. 19  in a first position; 
         FIG. 21A  is a top view of a first mold half useful to form an adjustable inline fluid rotation device according to a third embodiment; 
         FIG. 21B  is a bottom view of a second half mold insert for use with the mold half of  FIG. 21A  to form an adjustable inline fluid rotation device; 
         FIG. 22  is a bottom view of the first and second mold insert halves of  FIGS. 21A-B  combined and provided in a first exemplary extreme position to provide 0° fluid flow repositioning (with the lower first mold half being omitted for clarity); 
         FIG. 23  is a bottom view of the first and second mold insert halves of  FIGS. 21A-B  combined and provided in a second exemplary extreme position to provide an approximate 180° fluid flow repositioning (with the lower first mold half being omitted for clarity); 
         FIG. 24  is a top view of a first mold insert half to form an adjustable inline fluid rotation device according to another embodiment; 
         FIG. 25  is a bottom view of a second mold insert half for use with the mold half of  FIG. 24 ; 
         FIG. 26  is a view of the first and second mold insert halves of  FIGS. 24-25  combined (with the lower first mold half being omitted for clarity) in a first zero degree rotation position; 
         FIGS. 27-28  are views of the first and second mold insert halves of  FIGS. 24-25  combined in second and third positions, respectively, that result in rotations of approximately +/−180° relative to  FIG. 26 ; 
         FIGS. 29-30  are views of the first and second mold insert halves of  FIGS. 24-25  combined in fourth and fifth positions, respectively, that are each at an angle relative to  FIG. 26  that results in a melt rotation of about 90°; 
         FIGS. 31-32  are top views of alternative designs for the first mold insert half in which a compound radiused Y branch and a simple Y branch are used; 
         FIG. 33  shows a top view of yet another embodiment of first and second mold halves combined in an exemplary position (with the lower first mold half being omitted for clarity); 
         FIG. 34  is a top view of a first mold insert half according to a further embodiment in which there are two branched runner portions; 
         FIG. 35  is a bottom view of a second mold insert half for use with the mold half of  FIG. 34  (two would be used); 
         FIG. 36  is a bottom view of the first and second mold insert halves of  FIGS. 34-35  combined (with the lower insert mold half being omitted for clarity) in a first position and with the melt entering the runner  20 A with non-homogenous symmetrical conditions; 
         FIG. 37  is a bottom view of the first and second mold insert halves of  FIGS. 34-35  combined (with the lower insert mold half being omitted for clarity) in a second position and with the melt entering the runner  20 A with non-homogenous symmetrical conditions; 
         FIG. 38  is a bottom view of the first and second mold insert halves of  FIGS. 34-35  combined (with the lower insert mold half being omitted for clarity) in a third position and with the melt entering the runner  20 A with symmetrical non-homogeneous conditions; 
         FIG. 39  is a bottom view of the first and second mold insert halves of  FIGS. 34-35  combined (with the lower insert mold half being omitted for clarity) in the second position (the same as in  FIG. 37 ), but with the melt entering the runner  20 A with non-homogenous asymmetrical conditions; 
         FIGS. 40-44  are further variations of a melt positioner using a branching “Y” runner and a pair of movable inserts that split; 
         FIG. 45  is a cross-sectional view of an another embodiment of an adjustable melt flow diverter device in a first position; 
         FIG. 46  is a top view of the adjustable melt flow diverter device of  FIG. 45 ; 
         FIG. 47  is a cross-sectional view of the flow diverter device of  FIG. 45  in a second position; 
         FIG. 48  is a top view of the adjustable melt flow diverter device of  FIG. 47 ; 
         FIG. 49  is a cross-sectional view of the flow diverter device of  FIG. 45  in a third position; 
         FIG. 50  is a top view of the adjustable melt flow diverter device of  FIG. 49 ; 
         FIG. 51  is a view showing the approximate relative distribution of the high and low sheared materials as they flow through the adjustable flow diverter device of  FIG. 49 ; 
         FIG. 52  is a view showing the recombined distribution; 
         FIGS. 53-55  are partial cross-sectional views of an alternative exemplary fluid rotation device having a linearly adjustable flow diverter section comprised of a series of replaceable pins, each having a different effective height; 
         FIG. 56  is a cross-sectional view of a representative cold runner multi-cavity mold illustrating some of the potential locations of adjustable flow diverter devices; 
         FIG. 57  is a cross-sectional view of a representative hot runner mold illustrating some of the potential locations of adjustable flow diverter devices; 
         FIG. 58  is a cross-sectional view of various conventional hot runner nozzle tip designs; 
         FIG. 59  is a cross-sectional view of a first exemplary nozzle tip for a hot runner system capable of desired repositioning of asymmetric melt conditions; 
         FIG. 60  is a cross-sectional view of a second exemplary nozzle tip for a hot runner system capable of desired repositioning of non-homogeneous melt conditions; and 
         FIG. 61  is a side cross-sectional view of the nozzle tip of  FIG. 59 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Novel adjustable flow diverters are provided to achieve a desired positioning of non-homogeneous melt conditions of a laminar stream to manage downstream flow. Disclosed exemplary embodiments are particularly suited for use in molding processes in which the melt flow of thermoplastic materials are controlled in a runner system of a mold to remedy or create specific imbalance conditions that occur in any single or multi-cavity mold with a runner, which may branch in one or more directions, in which a variety or types of fluid can flow. Such imbalances occur for any fluid exhibiting (a) laminar flow and (b) viscosity that is affected by shear rate (as with a non-Newtonian fluid) and/or by temperature, or (c) characteristics where variations in shear or flow velocity across a flow channel will create variations in the materials characteristics. These characteristics are typical of thermoplastics, thermosetting materials and many of today&#39;s powdered metal and powdered ceramic molding materials. A polymer carrier is often employed with powdered metals and powdered ceramics. It is the polymer that gives such powdered metal or powdered ceramic materials the same characteristics as plastic materials exhibit in regards to viscosity effects and laminar flow. Accordingly, various aspects of the invention may be useful in controlling flow of various laminar fluids. However, control is not limited to improving flow balance. Rather, the main objective is to manage the melt for achieving a desired repositioning of the melt for a given purpose, such as control or influence on shrinkage, warpage and mechanical properties. 
     This repositioning may be, for example, so that fluid exiting a final branch enters a mold cavity in a desired state across the width of the cavity or has a desirable distribution of varied melt conditions across the cavity. Alternatively, in the case of a family mold with different sized mold cavities, it may be beneficial to purposely provide a certain non-homogeneous flow condition, such as an asymmetrical flow condition, to accommodate feeding of different sized cavities. Also, when multiple branches exist, there may be purposeful repositioning of the non-homogeneous melt condition at upstream branches so that a proper distribution is received at a particular downstream branch or runner to achieve an objective. 
     In accordance with aspects of the disclosure, adjustments to the flow geometry of a fluid rotation device can be readily made to reposition the non-homogeneous conditions of a laminar fluid flow to a desired position. In various exemplary embodiments, such adjustments occur without requiring remachining of mold components or extensive disassembly of the mold to replace mold inserts. Rather, such adjustments may take place insitu, while located in the mold, or through replacement of relatively minor or simple sub-insert features, such as a pin or gate insert. 
     In various exemplary embodiments, adjustment methods alter runner geometry to control the repositioning of the non-homogeneous fluid conditions through the runner. Such adjustments can be, for example, by a one-way or reversible adjustment. In certain embodiments, the adjustments can be made manually. In other exemplary embodiments, the adjustments can be controlled automatically through open or closed loop control to drive a powered adjustment mechanism through, for example, suitable pneumatic, hydraulic, mechanical or electrical drive mechanisms. 
       FIGS. 7A-C  illustrate a first exemplary embodiment that achieves adjustable rotation control of the non-homogeneous flow conditions in a stream of laminar fluid, such as in a hot or cold runner system, using an retractable flow diverter  130 . In this embodiment, mold insert halves  110  and  120  are provided to define portions of branching runners  32  and  38 . However, flow diverter  130  could be provided within a unitary mold insert or may be provided directly on a mold or hot runner manifold surface.  FIG. 8  shows a top view of branching runners  32 ,  38  formed by mold insert half  110  showing the flow diverter  130  being provided near the intersection of the runners. Mold insert  120  includes a region  125  that allows for an elevation change in the flow path of the laminar fluid. However, rather than having a fixed-position flow diverter, this embodiment uses a pin  130  as a flow diverter that can have its height adjusted in a direction perpendicular to the incoming flow path. In this example, the direction of adjustability extends substantially perpendicular to the direction of the molding machine platens. The pin  130  may be round or any cross-sectional shape, such as square, and may have rounded or beveled corners or edges. 
     The pin  130  can be adjusted by an external actuator  140  between various heights to change the angle of the flow path between two intersecting runners. When pin  130  is fully extended, as shown in  FIG. 7A , the flow path achieves a full elevational change into region  125 . This results in a flow path as shown and a circumferential repositioning of the high shear material by about 80-90°. However, as pin  130  is retracted from the mold insert so as to have a lesser area acting to divert flow, the angle that the flow path makes upon entry into the branching runner decreases as shown in  FIGS. 7B-C . This results in the ability to incrementally adjust the repositioning of the laminar flow rotation to predetermined values between about 0° and 90° by way of simple adjustment of pin  130 . 
     The external actuator can take several forms. In its simplest form, the pin may be press fit into an opening formed in the insert half  110  and adjusted through external force from a press, hammer, by hand, or by other source of urging force. Alternatively, a series of pins of differing heights could be provided and an appropriate pin inserted or press fit into the pin opening as shown in  FIGS. 53-55 . Such a pin  130  could be seated against a shoulder  132  on the bottom of opening  112  of the mold to precisely locate the pin. Thus, altering of geometry could be achieved through simple change of pins. This has cost advantages over remachining or even replacing of inserts because there is a need for only one mold insert having precision machined flow paths and a series of inexpensive pins of various heights to achieve a desired melt rotation. 
     Another possibility is to have the pin  130  be threaded and have a head manipulatable by a tool, such as a screwdriver or Allen wrench acting as an actuator to make adjustment. The head may include a knob serving as a handle allowing adjustment. Various powered actuators may also be used to extend pin  130 . The powered actuators may be manually controlled or controlled automatically through open loop or closed loop control. Suitable actuators can include various pneumatic, hydraulic, mechanical or electrical drive mechanisms. 
     Actuation need not be direct, but may act through various linkages or the like. An example of this is shown in  FIG. 9 . In this embodiment, adjustment is achieved through a manual actuator  140  that includes a fulcrum  142  provided within a region  112  of mold insert half  110 . One end of the fulcrum  142  rests against the bottom of the pin  130 . The other end of fulcrum  142  rests against a threaded rod  144  that is threaded into a recess  114  opening to a front face of mold insert half  110  that opposes the second mold insert half  120 . Threaded rod  144  includes a head  146  having a conventional configuration allowing it to be manipulated by an external tool, such as an Allen wrench or socket or screwdriver. Separating the two mold halves  110 ,  120  enables access to the head  146  without requiring removal of the insert from the mold assembly. Rotation of the head  146  acts on fulcrum  142  to allow incremental adjustment of pin  130  into the flow channel until a desired length of the pin  130  extends into the flow path. This enables a precise control of the flow diverter height to precisely adjust the elevation change of the flow path to cause a controlled circumferential rotation of the fluid flow as it transitions from the first runner  32  to the second branching runner  38 . Retraction of the pin  130  can be achieved by retracting the threaded rod  144 . When the friction fit of pin  130  in mold insert half  110  is sufficiently tight, it may be necessary to press down on pin  130  with a mallet, hammer, or other tool to retract the pin, or could be retracted by the melt pressure itself. Then, the threaded rod  144  can again be turned to precisely tighten or maintain tension against pin  130  by acting through fulcrum  142 . 
     It will be appreciated that, when the pin  130  has a beveled end as shown in  FIG. 9 , it should be prevented from retracting below a point where the maximum area cross-section of the bevel becomes level with the bottom of the runner  32 , to prevent flowing material from entering the resultant opening of mold insert half  110  in which the pin  130  travels. 
     Because of the laminar nature of the flow, a small dead space may be created at the intersection of the pin  130  and the runner  32 . This dead space, particularly when used in a cold runner, can provide the following advantage. Prior to injection from a nozzle, molten material at the tip of the nozzle can slightly cool, thereby forming a so-called “cold slug” of the material. It is desirable to prevent this cold slug from traveling through the runners to a mold cavity. The dead space at the intersection of the pin  130  and the runner  32  forms a cold slug well, which the cold slug enters. The liquid material behind the cold slug then goes around the cold slug and over the flow diverter, trapping the cold slug in place in the dead space. 
       FIGS. 10A-B  illustrate a second exemplary embodiment that achieves adjustable rotation control of the asymmetric fluid conditions in a laminar flowing stream. In this embodiment, adjustable control is achieved through a rotatable flow diverter  150  in the form of a disk mounted on a shaft  160 . Flow diverter  150  is notched to have an opening  152  having a predefined angle. The extent of the opening is dependent upon the amount of adjustability in flow desired. Flow diverter  150  also includes a leading end  154  that defines a flow diverter element. A maximum flow diverter cross-sectional area and height is shown in  FIG. 10A . Rotation of disk  150  counterclockwise reduces the profile at the leading edge  154  as shown in  FIG. 10B . With the shown profile having the leading edge  154  extending about 120°, there is limited adjustability. Additional adjustability could be achieved by modifying the leading edge  154  to create an angle up to 180°. This may enable a broader range of circumferential fluid rotation to values approaching as little as 0°. 
     As with the previous embodiment, adjustment of the flow diverter can be achieved through various manually operated or powered actuators (not shown). Simple examples would be to place a crank or handle on the end of shaft  160  or to have shaft  160  operably connected to a powered drive motor. 
     Various specific embodiments showing actuation of the rotatable disk will be described with reference to  FIGS. 11-15 . In the  FIG. 11  embodiment, flow diverter  150  includes a portion of the disk periphery that is provided with teeth  155 . Within a region of the mold insert half  110  is a drive motor  170  having a drive shaft  172  on which is mounted a drive gear  174 . Drive gear  174  mates with the teeth  155 . Motor  170  may be a stepper motor or other suitable motor as known in the art. Incremental or indexable rotation of drive motor  170  counterclockwise results in clockwise rotation of flow diverter  150  as shown. In order to form automated closed loop or open loop control of the adjustable flow diverter, drive motor  170  may be operably coupled to a controller  190 . Through suitable conventional sensors or command input controls, controller  190  can provide drive signals to drive motor  170  to precisely control the orientation of disk  150  so as to precisely control the fluid flow conditions by control of the flow path through the adjustable fluid rotation device. 
     Another exemplary embodiment showing manual actuation is shown in  FIG. 12 . In this embodiment, a rack and pinion system is used to index the rotation of flow diverter  150  inside the flow channel. In particular, as in the previous embodiment, flow diverter  150  includes an opening  152  and a peripheral surface with teeth  155 . An actuator  180  forming a rack and pinion assembly is provided within a region  114  of mold insert half  110 . The rack and pinion assembly includes a slidable rack having teeth  174  that mate with teeth  155  of the rotatable flow diverter  150 . A threaded rod  176  having a head  178  is screwed through a fixed block  175  and threaded onto the rack. Manipulation of threaded rod  176 , by applying an external tool to head  178 , will advance or retract the slidable rack, causing a precise control of rotatable flow diverter  150 . Access to the actuator  180  is achieved by opening of the mold, which separates the two mold insert halves enabling a user to access the top face of the mold insert and head  178  without requiring mold insert removal. 
     Another exemplary embodiment showing manual actuation is shown in  FIG. 13 . In this embodiment, the rotatable flow diverter  150  in the form of a disk is provided with a cam element  154  that protrudes from the outer periphery and can be engaged by an actuator  180  to cause precise rotation of the disk. In particular, a region  112  of the mold insert half  110  enables rotation of cam element  154 . Actuator  180  includes a threaded rod  184  having a head  186  mounted through a recess  114  opening to the front face of mold insert half  110 . Rotation of the threaded rod  184  using an external tool, such as an Allen wrench or screwdriver that mates with the head  186 , causes the threaded rod  184  to thread into ball joint  156 , urging cam element  154  toward or away from the threaded rod  184 . This results in rotation of rotating flow diverter  150  to a desired location. 
       FIG. 14  shows a modified version of the embodiment of  FIG. 13  in which the actuator  180  is provided perpendicular to the mold face of mold insert  110 . Rotation of threaded rod  184  causes cam element  154  to move similar to the previous embodiment. 
       FIG. 15  illustrates yet another exemplary embodiment showing manual actuation. This embodiment, similar to the embodiment of  FIG. 9 , achieves adjustment through a manual actuator that includes a fulcrum. In particular, manual actuator  180  provides a fulcrum  182  within a region of mold insert half  110 . One end of the fulcrum rests against the bottom of a pin  188 . The other end of fulcrum  182  rests against a threaded rod  184  that is threaded into an opening to a front face of mold insert half  110 . Threaded rod  184  includes a head  186  having a conventional configuration allowing it to be manipulated by an external tool. As in the  FIGS. 12-14  embodiments, opening of the mold may separate the two mold halves and enable access to the head  186  without requiring removal of the insert from the mold assembly. Rotation of the head  186  acts on fulcrum  182  to allow incremental adjustment of the pin  188 , which urges against surface  158  of rotatable flow diverter  150 , incrementally advancing the flow diverter to a desired rotation. 
       FIGS. 16-20  show additional embodiments of adjustable rotation control of the non-homogeneous flow conditions in a stream of laminar fluid, such as in a hot or cold runner system, similar to that disclosed in  FIGS. 7A-C . Both embodiments use a retractable flow diverter. In the embodiment of  FIGS. 16-18 , a mold half  1010  includes a flow diverter  1030  that is adjusted through actuator  1040  to change the angle of the flow path between two intersecting runners and thereby to adjust the rotation of the melt stream in the branching runner. Actuator  1040  includes an actuator pin  1042  that can be manipulated by a tool, such as by including a screwdriver or Allen wrench type head that mates with the tool. Gear teeth  1044  are provided on actuator pin  1042 . Corresponding gear teeth  1046  located on a threaded flow diverter shaft  1048  are mated to teeth  1044  so that rotation of actuator pin  1042  results in rotation of gear  1046  and an associated change of height in flow diverter  1030 . For example,  FIG. 17  shows the flow diverter  1030  in a low position while  FIG. 18  shows the flow diverter  1030  in a raised position. Separating the two mold halves enables access to the head of actuator pin  1042  without requiring removal of the insert from the mold assembly. This enables a precise control of the flow diverter height to precisely adjust the elevation change of the flow path to cause a controlled circumferential rotation of the fluid flow as it transitions from the first runner to the second branching runner. 
     Another embodiment is shown in  FIGS. 19-20 . In this embodiment, a mold half  1110  includes a flow diverter  1130  that is adjusted through actuator  1140  to change the angle of the flow path between two intersecting runners. Actuator  1140  includes a threaded actuator pin  1142  that can be manipulated by a tool, such as by including a screwdriver or Allen wrench type head that mates with the tool. An actuator block  1144  is threaded onto pin  1142  so that rotation of actuator pin  1142  results in raising or lowering of actuator block  1144 , which causes an associated change of height in flow diverter  1130 . As in the prior embodiment, separating the two mold halves enables access to the head of actuator pin  1142  without requiring removal of the insert from the mold assembly. This enables a precise control of the flow diverter height to precisely adjust the elevation change of the flow path to cause a controlled circumferential rotation of the fluid flow as it transitions from the runner to a downstream section, such as a branching runner, mold cavity, or other section of a runner system. Flow diverter  1130  is not limited to the square cross section shown. Flow diverter  1130  could also be rectangular, round or any other shape that causes the melt to be diverted. 
     A third exemplary embodiment provides an adjustable rotation control of the non-homogeneous laminar fluid conditions using an inline fluid rotation device structure that can be located along the length of a runner rather than at a branch in the runner.  FIG. 21A  illustrates a first mold half  210  that defines portions  32 A and  32 B of an inline runner section along with a flow diversion section  230  including a divergent flow path, shown in the exemplary form of an arcuate section, having ends  232 ,  236  and/or intermediate section  234 .  FIG. 21B  illustrates a second mold half  220  that defines a flow channel  225 . 
       FIGS. 22-23  illustrate the first and second mold halves being assembled together so that the flow region  225  connects runner portions  32 A at an interconnecting area  234  and runner portion  32 B at an interconnecting area shown at the end of runner portion  32 B, thereby forming a complete runner flow path. For ease of illustration, mold  210  is omitted so that the runner path can be better shown, and the runner portions  32 A and  32 B are shown superimposed over the mold half  220 .  FIG. 22  shows a condition in which the mold halves are in a first relative position.  FIG. 23  shows a condition in which the second mold half  220  is rotated about 90° relative to the orientation in  FIG. 22 . 
     In the position shown in  FIG. 22 , laminar material flow travels from section  32 A through end  232  into flow region  225  and out runner section  32 B. The result of this is about 0° rotation of the melt flow. However, when the second mold half  220  is rotated to the position shown in  FIG. 23 , laminar material flow travels from runner section  32 A through all of the flow diverter  230 , through end  236  into flow region  225  and out runner section  32 B. The result of this is almost 180° circumferential laminar fluid flow rotation. Thus, for example, if the high shear region is initially on the top, the high shear region may be rotated (i.e., repositioned) to near the bottom after flow diversion. 
     Use of the flow diverter  230  is not limited to the two extreme 90° offset positions as shown. Rather, it is possible to incrementally rotate mold insert half  220  so that the outer end of the flow region  225  meets with the divergent flow diverter section  230  anywhere along the intermediate section  234  that is the interconnecting area of runner portion  32 A. By this adjustability, flow repositioning within a range of about 0-180° circumferential rotation can be achieved inline of an individual runner, anywhere along its length. This allows for an additional adjustable control mechanism to fine tune the fluid flow as it travels along the runner to adjust for flow imbalance or to obtain other desirable positioning of the asymmetric meld conditions. 
     Numerous variants of this are possible. For example, region  225  can be extended in straight line form, as shown, or in an L or V shape extending from the center axis of the mold insert. Additionally, the flow diversion section  230  can be mirrored on the opposite side. This will allow a pair of flow diversion paths similar to that taught in U.S. Pat. No. 6,503,438 to Beaumont et al. Further, the divergent flow path could have variations in its path to provide various gradations in its rotation with the radial positioning of the mating  220  mold insert. 
     In various exemplary embodiments, the adjustments to the flow geometry are made while the mold is in an inoperative state. However, in certain circumstances, it may be beneficial to perform adjustment during operation of the mold while a laminar fluid is being flowed through the adjustable fluid rotation device. Because of this, the fluid rotation device is not only statically adjustable, but may be dynamically adjustable during the molding operation to fine tune the flow front of the laminar fluid during the actual filling of the mold. In such a situation, adjustment can be controlled by open loop or closed loop control using an automatic adjustment actuator and may include feedback from one or more mold process parameters. 
     For example, in the  FIG. 11  embodiment, pressure transducers or thermocouples may be located at various locations in the runner system or mold cavities to sense fluid pressure, timing or temperature variations across mold areas. This information may be used as control feedback by controller  190  to indicate the degree of remaining flow or cavity fill imbalance and allow fine tuning of the adjustment of the flow diverter  150  to reduce the imbalance in a next molding operation. Alternatively, this information could be used to derive a new control routine for a modified open loop control system. 
     Additionally, various pressure, timing, temperature or other signals can be used by controller  190  to dynamically control adjustment of the flow diverter  150  during the molding operation to adjust the flow front of the laminar fluid traveling through the branching runner system in real-time. Such dynamic adjustments can dramatically refine or customize the molding process by more precisely controlling or altering the flow front at various stages of the molding process. For example, such dynamic control can: alter cavity fill to accommodate a non-standard geometry; control or alter the molded part&#39;s warpage; control the distribution of stratified layers of material, such as high shear or low shear melt, to various cavities; and control many other special molding requirements to achieve stricter product tolerances or the like. 
     Depending on the mold processing time, such dynamic adjustment may be a discrete one move adjustment (from one value to another), or may be a continuously variable movement so as to precisely control dynamically the flow front of the laminar material. That is, successive sections of the material passing through the runner may be repositioned with different circumferential rotation. 
     Referring back to  FIGS. 21-23 , one of the two mold halves can be made with a small gap, on the order of 0.0005-0.001″ deep, to allow the mold halves to move relative to each other, even when the remainder of the mold is subjected to high mold clamp tonnage forces and melt pressure of over 20,000 psi. Similarly, referring back to  FIGS. 11-15 , a gap may exist around the rotatable flow diverter  150  in one or both mold insert halves to allow a clearance for rotation. 
     In embodiments where only static adjustments are made, it may be desirable to have a clearance in the lower mold insert containing the rotating disk to enable easier rotation. However, by eliminating a gap or clearance on the mating mold insert, upon closing of the mold and mating of the mold insert halves together, sufficient clamping pressure may be exerted on the rotating disk to prevent rotation during the molding operation. With this, adjustments can be achieved without requiring a large actuator force otherwise necessary to overcome the clamping force. Also, this gap is sufficiently small to retain fluid, particularly molten plastics, within the mold without excessive leakage. 
     Additionally, although exemplary embodiments are shown in the context of adjustment of the non-homogeneous fluid conditions after the branch in a runner with a two-piece mold insert, similar adjustable fluid rotation devices can be provided on a unitary insert or directly provided on mold or hot runner manifold surfaces used in cold or hot runner systems. Thus, aspects of the adjustable fluid rotation device and methods of adjustment can be used in cold runners or hot runners. 
     Another exemplary embodiment similar to that described in  FIGS. 21A-B  provides an adjustable rotation control of the non-homogeneous laminar fluid conditions using an inline fluid rotation device structure that can be located along the length of a runner, rather than at a branch in the runner.  FIG. 24  illustrates a first mold insert half  110  that defines runner portions  10 A and  10 B of an inline runner section. Runner portion  10 A is comprised of a binary arcuate flow path having a first end  330  and two arcuate flow paths. One arcuate flow path includes ends  332 ,  336 , and an intermediate section  334  of the interconnecting area of runner portion  10 A, and a second arcuate flow path includes ends  333 ,  340 , and an intermediate section  338  of the interconnecting area of runner portion  10 A.  FIG. 25  illustrates a second mold insert half  220  that defines a connecting runner portion  225 . 
     The flow geometry within mold half  110  can be fabricated directly into a mold body or may be included within an insert. The flow geometry within mold half  220  would typically be positioned within a mold insert to allow for rotation relative to mold half  110 . 
       FIGS. 26-30  illustrate the first and second mold halves being assembled together so that the connecting runner portion  225  unites runner portion  10 A at its interconnecting area  336 ,  334 ,  332 ,  333 ,  338 ,  340  and runner portion  10 B at its interconnecting area at the first end of runner portion  10 B, thereby forming a continual runner flow path. For ease of illustration, mold insert half  220  is omitted so that the runner path can be better shown, and the connecting runner portion  225  is shown superimposed over mold half  110 . 
       FIG. 26  shows a condition in which the mold halves are in a first relative position, with insert  220  at a zero degree rotation. In the position shown in  FIG. 26 , laminar flowing material travels from the first end of runner portion  10 A, beginning at end  330 , into and through connecting runner portion  225 , into the first end of  10 B, and finally, out of the second end of runner portion  10 B. The result of this flow path is approximately 0° circumferential laminar fluid flow rotation. 
     For reference, a cross section of non-homogeneous laminar fluid flow conditions entering the first end of runner portion  10 A is illustrated as  380 . Cross section  380  shows non-homogeneous laminar fluid flow conditions developed from top to bottom of the runner with the shaded region for reference existing on the bottom. Upon exiting the second end of runner portion  10 B, another cross section, cross section  381 , displays the asymmetric laminar fluid flow conditions and reveals that the relative portion of the asymmetric laminar fluid flow conditions entering and exiting the assembled mold halves have not changed. 
       FIGS. 27-28  show conditions in which the second mold insert half  220  is rotated approximately 90° relative to the 0° position shown in  FIG. 26 . When the second mold half  220  is rotated to the position shown in either  FIG. 27  or  FIG. 28 , laminar flowing material travels from the first end of runner portion  10 A, beginning at end  330 , through end  340  or  336 , respectively, of the interconnecting area of runner portion  10 A into connecting runner portion  225  and into the interconnecting area at the first end of runner portion  10 B and out of the second end of runner portion  10 B. The result of this flow path is almost 180° circumferential laminar fluid flow rotation, as represented by cross sections  382  and  383 . For example, if the high shear region is initially on the bottom, the high shear region may be rotated (i.e., repositioned) to near the top after flow diversion. The sole difference between cross sections  382  and  383  is the means in which the melt was rotated to this position as controlled by the rotation of the insert half  220  and laminar fluid flow. Cross section  382  is generated by a clockwise rotation of both insert and laminar fluid flow, while cross section  383  is generated by a counterclockwise rotation of both insert and laminar fluid flow. 
     The embodiment shown in  FIG. 24 , with a binary arcuate flow path, offers the option of flowing through either of the two arcuate flow paths in runner portion  10 A in order to more easily achieve the desired laminar fluid flow rotation. Each arcuate flow path is capable of generating laminar fluid flow rotation within a range of 0° to 180°. One arcuate flow path generates a means to rotate the laminar fluid flow in a range of 0° to 180° in the counterclockwise direction. The second arcuate flow path generates a means to rotate the laminar fluid flow in a range of 0° to 180° in the clockwise direction. Thus, this binary arcuate flow path design widens the laminar fluid flow rotation range to encompass all angles from a negative (counterclockwise) 180° rotation to a positive (clockwise) 180° laminar fluid flow rotation. Between the two arcuate flow paths, a full 360° rotational positioning of the melt stream can be achieved. 
     Use of the connecting runner portion  225  is not limited to the three extreme 90° positions as shown. Rather, it is possible to incrementally rotate mold insert half  220  so that the outer, first end, end of the connecting runner portion  225  meets with runner portion  10 A anywhere along the intermediate sections  334  or  338  of the interconnecting area of runner portion  10 A. By this adjustability, flow repositioning within a range of approximately negative 180° to positive 180° circumferential rotation can be achieved inline of an individual runner, anywhere along its length. This allows for an additional adjustable control mechanism to fine tune the laminar fluid flow as it travels along the runner to correct for melt imbalance which may result at a downstream branching runner or to obtain other desirable positioning of the asymmetric laminar fluid flow conditions for purposes such as to control the distribution of melt conditions within a downstream cavity or cavities. 
       FIGS. 29-30  show two variations of repositioning connecting runner portion  225  in order to meet with runner portion  10 A along the intermediate section  338  and  334 , respectively, of the interconnecting area of runner portion  10 A. When the mold insert half  220  is rotated to the position shown in either  FIG. 29  or  FIG. 30 , laminar flowing material travels from the first end of runner portion  10 A, beginning at end  330 , through intermediate section  338  or  334 , respectively, into connecting runner portion  225  and out of the second end of runner portion  10 B. The result of this flow path is approximately 90° circumferential laminar fluid flow rotation, as represented by cross sections  384  and  385 . For example, if the high shear region is initially on the bottom, the high shear region may be rotated (i.e., repositioned) to the left or right side after flow diversion. 
     As shown in  FIGS. 29-30 , rotation of mold insert half  220  to some position greater than 0°, but less than approximately 30° relative to the orientation shown in  FIG. 26  may generate a laminar fluid flow rotation of approximately 90°, as shown by cross sections  384  and  385 . However, as shown in  FIGS. 27-28 , an additional 60° or more rotation (total of about 90° or more) insert rotation is required in order to generate an additional 90° laminar fluid flow rotation. Similar to cross sections  382  and  383 , the rotations generated in cross sections  384  and  385  are also produced using opposite directional insert rotation and laminar fluid flow rotation. The result is a non-linear relationship of insert rotation to laminar fluid flow rotation with these designs having binary arcuate flow paths, which may lend itself to design alterations as shown in  FIGS. 31-32 . 
     Numerous variants of runner portion  10 A are possible. For example, as shown in  FIG. 31 , runner portion  10 A includes a binary compound radiused Y branching.  FIG. 32  shows an optional design where runner portion  10 A includes a simpler binary Y branching with no radiused portions. These variants of runner portion  10 A can be used to adjust the relationship between mold insert rotation and laminar fluid flow rotation. These designs generate a more evenly proportioned ratio of insert rotation to laminar fluid flow rotation. These designs, or variations of them, can be employed so that an insert rotation of 45°, relative to the orientation shown in  FIG. 25 , generates a 90° laminar fluid flow rotation, while doubling the insert rotation to 90° generates double the laminar fluid flow rotation, totaling 180°. 
     Numerous variations of runner portions  10 A,  10 B, and connecting runner portion  225  are possible. For example, connecting runner portion  225  can be extended in straight line, as shown in  FIGS. 24-30 , or in an L or V shape and the divergent interconnecting area of the runner portion  10 A can be mirrored on the opposite side as shown in  FIG. 33 . Further, the divergent interconnecting area of a runner portion could have variations in its path to provide for multiple gradations in its rotation with the radial positioning of the mating  220  mold insert. 
     Designs such as the one shown in  FIG. 33  provide for a smaller insert rotation to generate a larger laminar fluid flow rotation when compared to the designs in  FIGS. 24-32 . The reduction in required rotation of insert  220  could reduce the size of the insert. For example, an approximately 30° clockwise insert rotation may generate the approximately positive 180° laminar fluid flow rotation shown by cross section  386 , while an approximately 30° counterclockwise insert rotation may generate an approximately negative 180° laminar fluid flow rotation. The ability to provide a positive and negative 180° rotation of the laminar flowing material provides up to a full 360° control of the rotational positioning of the laminar flowing fluid. 
     In the descriptions of  FIGS. 26-33 , the amount of rotation of insert half  220  needed to achieve a given rotation of the laminar fluid is only approximated. The actual rotation would be dependent on the size, shape, and relative positioning of the interconnecting area of runner sections  10 A and  10 B, and of connecting runner section  225 . 
     Exemplary embodiments provide an adjustable rotation control of non-homogeneous distributed laminar fluid conditions using an inline fluid rotation device structure that can be located along the length of a runner, such as intermediate the length of the runner or at a part forming cavity entrance. The following describes its application in the strategic positioning and asymmetrically distribution of laminar fluid condition.  FIG. 34  illustrates a first mold insert half  500  that defines runner portions  20 A and  20 B of an inline runner section. Runner portion  20 A is comprised of melt feed portion beginning at  530  which branches at intersection  560  into two branching runner portions  401  and  402 , each of which then exit into binary arcuate flow paths. Runner portion  401  feeds into a first binary arcuate flow path having a first arcuate flow path which includes ends  536 ,  534 , and intermediate section  535  that forms a portion of a first interconnecting area of runner portion  20 A, and a second arcuate flow path which includes the intermediate section  580  that completes the first interconnecting area. Runner portion  402  feeds into a second binary arcuate flow path having a first arcuate flow path which includes the intermediate section  581  and a second arcuate flow path includes ends  554 ,  552 , and intermediate section  553  that together form a second interconnecting area of runner portion  20 A.  FIG. 35  illustrates one of a pair of a second mold insert half  220  that defines a connecting runner portion  225 . 
       FIGS. 36-39  illustrate mold halves  500  and a pair of mold insert halves  220  assembled together so that the connecting runner portions  225  unite runner portions  20 A and  20 B, thereby forming a continual runner flow path. For ease of illustration, mold insert half  220  is omitted so that the runner path can be better shown, and the connecting runner portion  225  is shown superimposed over mold half  500 . 
       FIG. 36  shows a condition in which the mold halves are in a first relative position, with insert  220  at a zero degree rotation. In the position shown in  FIG. 36 , laminar flowing material travels from the first end of runner portion  20 A, beginning at end  530 , splitting at intersection  560 , into branching runner portions  401  and  402 . The flow exiting branching runner portion  401  intersects with the first binary arcuate flow path and connecting runner portion  225 . The first and second portions of the first binary arcuate, including intermediate sections  535  and  580  that form an interconnecting area for runner portion  20 A, are quickly filled with laminar flowing material and flow ceases within these portions. Flow through connecting runner portion  225  provides a continuous flow path for the laminar flowing material. Material exiting the first branching runner portion will change elevation, relative to the view shown, as it enters connecting runner portion  225  located on the second mold half  220 . The laminar flowing material will exit connecting runner portion  225 , changing elevation as it returns to mold half  500 , and continue to flow to intersection  565  where it will recombine with the laminar flowing material, that had split into branching runner portion  402 , and exit. The combined laminar flowing material will then flow into an interconnecting area at the first end of runner portion  20 B, and finally, out of the second end of runner portion  20 B. The result of flowing through the geometries as described will be an approximate 0° circumferential laminar fluid flow rotation. The material will have approximately the same distribution of material properties exiting runner portion  20 B as it did when it entered runner portion  20 A. 
     For reference, a cross section of symmetrical laminar fluid flow conditions entering the first end of runner portion  20 A is illustrated having a high sheared material around the perimeter  510  and low sheared material  515  in the center of the melt stream. Upon exiting the second end of runner portion  20 B, a cross section  520 , displays the same symmetrical laminar fluid flow conditions revealing that the relative position of the laminar fluid flow conditions entering and exiting the assembled mold halves have not changed. 
       FIG. 37  shows conditions in which the second mold insert half  220  is rotated approximately 30° relative to the 0° position shown in  FIG. 36 . The 30° rotation of mold insert half  220  is counterclockwise for the top binary arcuate flow path and clockwise for the bottom binary arcuate flow path. When the second mold halves  220  are rotated to the positions shown in  FIG. 37 , laminar flowing material travels from the first end of runner portion  20 A, beginning at end  530 , and splits symmetrically in half at intersection  560  into branching runner portions  401  and  402 . The melt traveling through branching runner portion  401  enters the first binary arcuate flow path and flows with a continuing flow into the first arcuate flow path beginning at end  536 , through a portion of the intermediate section  535  of one interconnecting area of runner portion  20 A. The melt will then change elevation, relative to the view shown, and then change flow directions as it enters connecting runner portion  225  located on the second mold half  220 . The compound change in flow direction created by the change in elevation and the relative 90 degree flow direction of the first portion of the arcuate flow path, beginning at  536  and ending at  534 , to the connecting runner portion  225 , will cause the melt to be repositioned by approximately 90 degrees in the circumferential direction, relative to its position in the first branching runner portion. The laminar flowing material will exit connecting runner portion  225 , changing elevation as it returns to mold half  500 , and flow direction as it flows through a portion of intermediate arcuate section  544  of an interconnecting area of runner portion  20 B. The compound change in flow direction created by the change in elevation and the relative 90 degree flow direction of the connecting runner portion  225  the portion of the arcuate flow path, beginning at  543  and ending at  545 , will cause the melt to be repositioned by approximately an additional 90 degrees in the circumferential direction, relative to its position in the first branching runner portion  401 . The approximate 90 degree rotation of the melt stream resulting in the connecting runner portion  225  and the additional approximate 90 degree rotation of the melt stream resulting in the intermediate portion  544  of the arcuate runner section, will cause the melt exiting the arcuate flow path at  545  to have been rotated approximately 180 degree in the circumferential direction relative to its original position in the branching runner portion  401 . The melt then exiting from the arcuate flow path at  545  will combine with the melt which had branched into runner portion  402  at intersection  565 . If the connecting runner portion  225  were rotated approximately 30 degrees in a clockwise direction, as shown in  FIG. 37 , the melt approaching intersection  565  from runner portions  421  and  422  will have been rotated in a counterclockwise direction approximately 180 degrees. Upon merging the two melt streams at intersection  565 , the high sheared materials, originally around the perimeter of the flow channel  20 A, will have been repositioned as shown in cross section  521 . 
     Each of the four arcuate flow paths is capable of generating laminar fluid flow rotation within a range of 0° to 180°. Each of the two binary arcuate flow paths generate a means to rotate the laminar fluid flow in a range of 0° to 180° in either the clockwise or counterclockwise directions, dependant on the positioning of the connecting runner portions  225 . Given the counter clockwise positioning of the top connecting runner portion  225 , shown in  FIG. 37 , the melt will be rotated approximately 180 degrees in the counterclockwise direction as referenced from the direction of flow. The clockwise positioning of the lower connecting runner portion  225  will cause the melt to be rotated approximately 180 degrees in the clockwise direction as referenced from the direction of flow. 
     As seen in  FIGS. 36-38 , the use of the connecting runner portions  225  is not limited to any particular position. Rather, it is possible to incrementally rotate each mold insert half  220  so that the outer, first end, end of the connecting runner portions  225  meets with runner portion  20 A anywhere along the intermediate arcuate sections  535 ,  580 ,  553  and  581  of the interconnecting areas of runner portion  20 A. By this infinite adjustability, flow repositioning within a range of approximately counterclockwise 180° to clockwise 180° circumferential rotation can be achieved inline of an individual runner, anywhere along its length. This allows for an additional adjustable control mechanism to fine tune the positioning of melt property variations in a laminar fluid flow as it travels along the runner to correct for melt imbalance which may result at a downstream branching runner or to obtain other desirable positioning for purposes such as to control the distribution of melt conditions within a downstream part forming cavity or cavities. 
       FIGS. 36-38  show three variations of repositioning connecting runner portion  225  in order to meet with runner portion  20 A along the intermediate sections  535  or  580 , and  553  or  581 . Mold insert half  220  can be rotated to infinitely many positions along these intermediate runner sections in order to manipulate the rotation of the laminar fluid flow to the desired positioning. 
       FIG. 38  shows the connecting runner portions being rotated to a position which would cause the melt variations represented by symmetrical position of the dark regions in cross section  512  to be repositioned to an asymmetrical top position as shown in cross section  522 . This would require an approximate 90 degree clockwise rotation of the melt from its original position on the right side of runner section  401  and an approximate 90 degree counterclockwise rotation of the melt from its original position on the left side of runner section  402 . 
       FIG. 39  shows a variation of the application of this invention where the melt entering runner section  20 A has the asymmetrical conditions shown in cross section  516 . By controlling the rotational position of the melt stream, as previously described in  FIG. 37 , the two halves of the melt stream will be rotated 180 degrees such that when the are recombined, the asymmetric top to bottom conditions shown in cross section  516  will be repositioned 180 degrees as shown in cross section  518 . 
     In the descriptions of  FIGS. 34-39 , the amount of rotation of insert half  220  needed to achieve a given rotation of the laminar fluid is only approximated. The actual rotation would be dependent on the size, shape, and relative positioning of the various runner sections,  10 A,  10 B,  20 A, and  20 B, and of connecting runner section  225 . The rotation of inserts  220  in  FIGS. 21-39  can be actuated manually from the face of the mold through direct manipulation of the insert  220  or indirectly through a gear mechanism or by some other means. Additionally the rotational motion can be controlled through a manual, motor or linear drive means using gears or rack and pinion methods which could be mounted internal to the mold or external to the mold. 
     The additional control gained with two binary arcuate flow paths opposed to one, as presented in  FIGS. 24-33 , is the ability to split the laminar fluid flow stream into two separate streams. The laminar fluid flow rotations of these two streams can then be independently, or dependently, controlled. The two laminar fluid flow streams can then be rotated to mirror one another, or both rotated in the same clockwise or counter clockwise direction, or rotated to various positions which are totally independent of one another. The flow streams may then be recombined and exit at  20 B. 
     The flow geometry within mold insert half  500  can be, but does not necessarily have to be, fabricated directly into a mold body or may be included within an insert. As with mold insert half  500 , the flow geometry within mold insert half  220  would typically be, but is not required to be, positioned within a mold insert to allow for rotation relative to mold half  500 . 
     The flow geometry used in all of the above mold insert halves can be utilized in either hot or cold runner molds and in molds having solidifying or non-solidifying runners. Designs such as the ones shown above provide for a greater control of melt positioning. In these designs, the melt can be split into two, rotated equally or variably and rejoined to form a melt with the desired fluid flow rotation and melt condition positioning. 
     The above embodiment is only one example of a means to provide adjustable control of the position and distribution of the variations in melt conditions existing in a stream of laminar flowing fluid.  FIGS. 40-42  are further variations of the above melt positioner. This design uses a pair of movable inserts,  610 A and  610 B, which move approximately perpendicular to a plane defined by the centerline of the path of two flowing streams of laminar flowing material which intersect the pair of movable inserts. In a cold runner system, the inserts could be moved in a direction approximately perpendicular to the parting line of the mold where the molds runner system travels. Melt approaches the pair of movable inserts along runner portion  601 . The melt is then split into the two “Y” branching runner portions  602 A and  602 B. If the melt approaching the branching “Y” runner portions has a distribution of high sheared melt around the perimeter of the flow channel  611  and low sheared melt in the center  612 , as shown in  FIGS. 41-42 , the high and low sheared material will be split and redistributed such that the high sheared material is positioned to the left side  616  of the left branch of the “Y” branching runner  602 A and to the right side  615  of the right branch of the “Y” branching runner  602 B. At the exit of the two branching runner portions  602 A and  602 B, the melt enters the flow geometry created between the pair of movable inserts  610 A and  610 B. The position of the pair of movable inserts will control the initial direction that the material flows as it exits the two “Y” branching runner portions. When the paired movable inserts are positioned such that they create a flow channel along a same plane as the two “Y” branching runner portions and the first portion of an exiting runner portion  603 , the position referred to here as the “neutral position,” the melt will exit each of the two “Y” branching runner portions and turn directly toward the entrance of runner portion  603  along a converging flow channel  604  and exit through runner portion  604  without making any elevation changes. The result is that the melt exiting through runner portion  604  will have nearly the same distribution of high  613  and low  614  sheared material conditions as the melt entering through runner portion  601 . 
     With the pair of movable inserts in its upper most position ( FIGS. 43 and 44 ), the flow channel will be modified such that the melt exiting the two “Y” branching runner portions will travel in the upward direction along a first  605 A and second  605 B height adjustment flow path, approximately 90 degrees relative to a reference plane defined by the centerline of the “Y” branching runners  602 A and  602 B. The melt will then exit the height adjustment flow paths  605  and make a second directional change, approximately 90 degrees relative to both runner portion  602  and flow path  605 , into the melt converging flow channel  604 . The compound angle changes in the melt flow direction between the entrance and exit of the height adjustment flow path  605 A will cause the melt in the left portion of the converging flow channel  604 A fed from the left branch of the “Y” branching runner to be rotated in a circumferential direction approximately −90 degrees relative its position in the left branch of the “Y” branching runner such that if high sheared laminates were traveling along the left side  618  of the left branch of the “Y” branching runner they would now be on the top side  620  of the left portion  604 A of the converging flow channel. 
     The compound angle changes in the melt flow direction between the entrance and exit of the height adjustment flow path  605 B will cause the melt in the right portion of the converging flow channel  604 B fed from the right branch of the “Y” branching runner to be rotated in a circumferential direction approximately 90 degrees relative its position in the right branch of the “Y” branching runner such that if high sheared laminates were traveling along the right side  617  of the right branch  602 B of the “Y” branching runner they would now be on the top side  619  of the right portion  604 B of the converging flow channel. 
     The melt in the left and right portions of the converging flow channel, will converge into a single flow path traveling downward along a third height adjustment flow path  621 , in a direction which is approximately 90 degrees relative to a reference plane defined by the centerline of the “Y” branching runners. Laminar flow conditions will result in the melt from the left portion of the converging flow channel  604 A to flow along the left side of the height adjustment flow path  621  and the melt from the right portion of the converging flow channel  604 B to travel along the right side of the height adjustment flow path. The high sheared material traveling along the top of the converging flow channel portions will become positioned along the center of the third height adjustment flow path  621  as shown as  625  exiting runner portion  603 . At the exit of the third height adjustment flow path  621  the melt will make an approximate 90 degree turn relative to the direction of the third height adjustment flow path and the converging flow channel into a runner portion  603 . These compound angle change between the entrance and exit of the height adjustment flow path will cause the melt in the left and right side of runner portion  603  to be rotated in a circumferential direction approximately plus and minus 90 degrees relative to its earlier position in the converging flow channels  604  and 180 degrees relative to its original position in runner portion  601 . The high sheared material originally around the perimeter  611  of the melt stream is now positioned  625  along a center reference plane defined by the center line of the height adjusting flow path  621  and the runner portion  603  and the low sheared material originally in the center  612  of the melt stream of runner portion  601  is now positioned on the opposite outward sides  626  of the flow channel  603  along the same reference plane. 
     By positioning the pair of movable inserts  610 A and  610 B such that they are positioned between the uppermost position (described above) and the neutral position, the direction of flow between the entrance and exit of the height adjustment flow paths  605  and  621  will be modified relative to the neutral position and the uppermost position causing the amount of rotation of the melt stream to be altered. By this means of modifying the direction of flow through adjusting the height of the pair of movable inserts, the amount of rotation, and the final distribution of the high and low sheared material within the melt flowing through runner channel  603  can be controlled. 
     By positioning the pair of movable inserts  610 A and  610 B such that they are positioned below the neutral position, the directions of flow in connecting runner portions  605  and  621  will be opposite to that achieved by positioning the pair of adjustable inserts in the upper position. This will cause the repositioning of the melt to be in the opposite circumferential direction as described when the inserts were in the upper position. 
     The angle between runner portions  602  and  605 ;  605  and  604 ;  604  and  621  can be modified to effect the melt rotation that is created in this invention. 
     A further embodiment of this invention is shown in  FIGS. 45-46 .  FIG. 46  is a top view of portions of  FIG. 45 .  FIGS. 45-46  show a representation of a method for managing the distribution of melt variations that may exist across the channel of a laminar flowing material. In the case of a flowing material with high sheared melt conditions distributed circumferentially around the perimeter  720  and the low shear material positioned in the center  721  of the flow channel, material entering flow channel  701  exits into channel  703  where in  FIG. 45  it flows downward vertically, and then relative to  FIG. 46 , the flowing material exits channel  703  and branches left and right into two arcular runner portions  704 A and  704 B, the inner radius of these arcular runner portions created by a retractable circular pin  706 . The branching of the laminar flowing material at the exit of  703  will divide the flowing material into the two arcular runner portions  704 A and B. This will cause the high sheared materials  720  originally around the perimeter of the melt entering through  701  to be rotated approximately 90 degrees such that the high sheared material around the left half, relative to the left branching arcular runner, of the perimeter of flow channel  701  is now positioned on the top 740 of the laminar flowing melt stream flowing through the left branching arcular runner portion  704 A. The high sheared material around the right half, relative to the right branching arcular runner, of the perimeter of flow channel  701  is now positioned on the top 740 of the laminar flowing melt stream flowing through the right branching arcular runner portion  704 B. The low sheared material originally in the center of melt entering through  701  will be rotated approximately 90 degrees such that it is now positioned on the bottom  741  of the two laminar flowing melt streams flowing through the arcular runner portions  704 A and B. At the end of the arcular runner portions the melt will recombine at the entrance of a vertical flow channel  705 . The approximately 90 degree change in flow direction as the laminar flowing material flows from the two arcular runner portions  704 A and B into the vertical runner portion  705  causes the high sheared material positioned on the top of the arcular runner portions to be positioned along the center of the runner portion  705 . Upon exiting the vertical runner portion  705  and entering  702 , the high sheared material originally positioned around the perimeter of the melt stream entering through runner portion  701  will have been rotated approximately 180 degrees such that it is positioned along a vertical plane that divides the flow path  702  with the high sheared material  722  along the center of the flow path and the low sheared material  723  along the outer left and right sides of the flow path. The effect is that the high sheared material along the left and right side of the perimeter of the flow channel  701  has been rotated counterclockwise by approximately 180 degrees within each of the two flow branches such that when recombined they are now positioned along the center of the flow channel. 
     The amount of rotation can be affected by the length of runner portions  703  and  705  and the shape of the center adjustable pin. Shortening runner portion  703  to a zero length will significantly eliminate the flow angle change at the intersection of runner portion  701  and  703  such that there is virtually no rotation of the melt stream. Melt conditions on the left half of the runner portion  701  will remain on the left half of the left branching arcular runner portions  704 A and melt conditions on the right half of the runner portion  701  will remain on the right half of the right branching arcular runner portions  704 A. Similarly, shortening runner portion  705  to a zero length will significantly eliminate the flow angle change at the intersection of runner portion  705  and  702  such that virtually no rotation of the melt stream results. Melt conditions on the left and right side exiting arcular runner portions  704 A and B will remain significantly on the left and right side portions of the combined melt stream flowing through runner portion  702 . 
     Alternate geometries, which decrease any of the flow angle changes, will decrease the amount of circumferential rotation of the melt. In some cases it may not be necessary, or desirable, to rotate the melt by as much as  180  degrees in each of the split flow streams. 
     This invention provides a means of adjusting the distribution of the high and low sheared materials by the vertical positioning of pin  706 . By fully retracting the pin as shown in  FIG. 47 , the arcular runner portions  704 A and B shown in  FIG. 45 , are eliminated, as their inner radius defined by the protruding pin has been eliminated. Therefore the laminar flowing material entering from runner portion  701  will fill the chamber, left by the retracted pin  706  and the remaining geometry of the former arcular flow paths, and then streamline across to runner portion  702 . In contrast to the approximate 180 degree rotations achieved with the pin in the uppermost position as described above, with the pin in the lower most position there will be no circumferential rotation or repositioning of the laminar flowing fluid in runner portion  702  relative to its original position in runner portion  701 . As the pin is progressively raised into the melt stream, as shown in  FIG. 49 , it increasingly interrupts the laminar flowing material causing portions of the melt to be diverted into the runner portions  703 , arcular channels  704 A and B, and runner portion  705  while portions of the laminar flowing material bypass these channels and flow across the top of the partially raised pin  706 . The laminar flowing material diverted into the channels  703 , arcular runner portions  704 A and B, and  705  will be rotated similarly as described above in conjunction with  FIG. 45 . The high and low sheared laminar flowing material flowing across the top of the vertically adjustable pin will maintain their approximate relative positions. The approximate relative distribution of the high and low sheared materials as they flow through the left and right sides of the pin and across the top of the pin, is shown in  FIG. 51 . Once recombined, they will be distributed approximately as shown in  FIG. 52 . The higher the position of the pin, the more the amount of material is diverted to the outer two arcular runner portions and the more dominate their effect relative to the laminar flowing materials traveling across the top of the pin. 
     This invention may be applied to any laminar flowing fluid in order to achieve a desirable effect and is not limited to a melt. The invention can be applied to solidifying or non-solidifying laminar flowing fluid as might be experienced in a cold or hot runner mold used for molding plastic parts. The invention can be within a mold, die, manifold, machine nozzle, hot runner system or any other geometry that contains a laminar flowing fluid, each of which is referred to generally as a tool. The terms flow path and runner portions are interchangeable. 
     Referring to  FIGS. 53 ,  110  and  120  are inserts in a cold runner mold, which when combined with a replaceable sub-insert  130  provide for melt rotation for the melt entering a branching runner  38 . Sub-insert  130  may be in the form of a pin as shown having a round, square or rectangular cross-sectional shape. In this embodiment, there are a plurality of differently configured pins  130 . The degree of rotation is determined by the angle of flow path shown by the arrow as it transitions between chamber  125  in the upper insert  120  and the top of the sub-insert  130  and into the branching runner  38 . In this particular example, sub-insert  130  in the form of a pin is sized to fit within an opening  112  in lower insert  110 . The opening may include a step, flange or other mating structure to achieve a controlled positioning and retention of the pin once fully inserted. This enables the pin to extend a precise height into chamber  125 . 
     Aspects of the invention can also improve upon previous fixed melt rotation devices by providing adjustable melt rotation control through replacement of one or more small, easily replaced adjustment features within a melt rotation device. This replacement is significantly simpler and cheaper than remachining of the melt rotation geometry in the mold, mold insert, or hot manifold, hot nozzle or insert within the hot manifold or hot nozzle. It also requires fewer components than a single, repositionable adjustable flow diverter device with an external actuator. Examples of replaceable features might come from a stock of pre-made inserts, or sub-inserts as illustrated in  FIGS. 53-55 .  FIGS. 53-55  are similar to  FIGS. 7A-C  in function. However, rather than having a single, adjustable flow diverter  130  in the form of a pin, this embodiment relies on a series of replaceable pins that can be substituted to adjust the melt rotation. It is envisioned that such a melt rotation device would consist of a mold, mold insert or manifold and a plurality of replaceable sub-inserts, each having a different profile or height to provide a differing melt rotation. 
     Melt rotation can be simply adjusted by opening of the mold, removal of the sub-insert  130  in the form of a pin, and insertion of another of a series of differently configured pins. For example, in  FIG. 54 , sub-insert  130 ′ has been substituted, which has a lesser height than the sub-insert  130  from  FIG. 53 . As a result, there is a reduced flow angle, which reduces the rotation of the melt stream entering branching runner  38 . A further example is shown in  FIG. 55  where sub-insert  130 ′ is the same as in  FIG. 54 . However, the height of chamber  125  in upper insert  120  has been reduced a similar amount as the height of sub-insert  130 ′. This also reduces the flow angle of the melt flow path as it transitions between the runner portion defined between chamber  125  in insert  120  and the top of the sub-insert  130 ′ and into the branching runner  38 . 
     This embodiment results in large cost advantages and simplicity over complete remachining of mold inserts or replacement of entire mold inserts. This is because there is the need for only a single machined mold, mold insert or insert pair or manifold having precision machined or formed flow paths and a series of readily exchangeable and inexpensive sub-inserts (e.g., pins) of various heights or profiles to achieve adjustment. Moreover, by provision of a simple flange or the like, the sub-inserts can be reliably positioned and secured, eliminating the need for a more complex adjustment mechanism. 
     As shown in  FIGS. 56-57 , provision of a flow diverter  100  according to any of the above embodiments is not limited to provision at a branch location. Rather, one or more flow diverters  100  can be provided anywhere in the runner system as shown.  FIG. 56  shows flow diverters  100  provided at inline and branch locations of runners  30 , as well as at the entrance to a mold cavity  250 .  FIG. 57  shows flow diverters provided at various locations within a hot runner system  300 , including within a hot runner manifold (of the single mold type or stack mold type) at inline or branch locations. Also, such flow diverters  100  can be provided at an entrance to a nozzle, hot drop, nozzle tip or valve gate. 
     Adjustments in hot runners could be provided by a similar means or structure, but with designs that result in more streamlined flow paths that minimize low, or stagnant, flow regions that could result in degradation of the melt or provide for flushing of stagnant regions. 
     Additionally, adjustment in hot runner systems could result from replacing removable tip inserts containing melt rotation geometry designed to provide desirable rotation of the melt stream. Though easily replaceable tip inserts are commonly used in hot nozzles, as shown by tip inserts  1200 ,  1200 ′,  1200 ″,  1200 ′″, and  1200 ″″ in  FIG. 58 , they have not been designed or specifically positioned to provide desirable rotation of the melt. Instead, such nozzle tips are commonly randomly oriented in the hot runner system. 
       FIGS. 59-61  show several varieties of nozzle tip designs which, when strategically positioned relative to incoming non-homogeneous melt conditions, can be used to control the repositioning of the melt to a desired position. Additionally, the specific geometry or offset can be modified to achieve a desirable melt rotation.  FIG. 59  shows a first exemplary hot nozzle tip insert  850  that may include a sub-insert  810 . Nozzle tip assembly  810  and  850  are attached to the downstream end of the nozzle body  805 , which extends through mold plate  800 . Incoming non-homogeneous melt conditions enter lower chamber  820  and feed through an internal branching chamber  830  that exits on opposite sides (out of the paper and into the paper in the view shown) into a chamber  840  defined between insert walls  800  and a conical nozzle tip  850 . The branching of the flow results in a certain elevational change and an associated melt rotation. By control of this branching, or offset in geometry from a centroid of the nozzle tip, a predetermined fluid repositioning can occur so fluid exiting a tip  860  can have a managed melt condition as it exits the nozzle tip for a desired effect. Control may also be achieved by the relative rotation of the nozzle tip relative to the incoming fluid stream. 
       FIGS. 60-61  show a second exemplary hot nozzle tip insert  850  of a different type. In this example, incoming melt enters chamber  820  and feeds through internal branching  830  and exits on opposite sides into an annular chamber  870 . From chamber  870 , the melt flows into chamber  840  defined between nozzle insert walls and a conical nozzle tip  850 . From chamber  840 , the melt exits tip  860 .  FIGS. 59-61  are similar to the technology in U.S. Pat. No. 6,503,438 to Beaumont et al. and achieve a recombination of melt along multiple axes. For example, if the incoming melt were coming straight from the sprue, with no branches and symmetry to the melt conditions at the entrance to chamber  820 , the melt would split and recombine similar to  FIG. 44 . 
     Dynamic control of melt rotation in a hot runner system could be provided in the hot nozzle of the hot runner system by using an adjustable pin whose adjustment could be the radial, linear or combination of radial and linear positioning of the pin. The pin could be similar to linearly movable pins commonly used in mechanically actuated valve gated hot runner nozzles. A melt repositioning device could be defined within the pin or between the pin and the flow channel walls of the hot nozzle in which the pin is inserted. Movement of the pin would result in the modification of the flow channel geometry, or positioning of the flow channel geometry, resulting in the repositioning of asymmetric melt conditions to a desirable position. Adjustment could occur at the nozzle tip or anywhere along the length of the nozzle. The adjustment can be achieved through a manually operated actuator mechanism or a machine-driven actuator mechanism. Adjustment could occur as melt is traveling through the runner system to the part forming cavity. 
     The invention is not limited to use with hot or cold runner molds as used with thermoplastic injection. The invention could be used with any solidifying or non-solidifying runner mold with any laminar flowing material capable of developing non-homogeneous melt conditions across a flow channel. Additionally, the invention could be used with any other plastic process equipment or process including extrusion or blow molding where non-homogeneous melt conditions can develop across a flow channel. Further, the invention could be used with any non-plastics processes or equipment where it may be desirable to adjustably control the distribution of non-homogeneous fluid conditions across a steam of laminar flowing fluid. 
     The invention has been described with reference to several preferred embodiments, but these embodiments are illustrative and non-limiting. Various modifications, substitutes and/or improvements may be possible within the spirit and scope of the invention.