Patent Publication Number: US-2022219363-A1

Title: Side-gate injection molding apparatus and side-gate hot runner nozzle

Description:
FIELD 
     The present relates to side-gate injection molding and more particularly, to a side-gate hot runner nozzle having a biased tip assembly. 
     BACKGROUND 
     A challenge associated with side-gate injection molding includes replacing a tip or tip assembly without cumbersome dismantling of the side-gate hot runner system. Another challenge associated with hot runner side-gate injection molding includes creating a fluid seal between the tip and the nozzle body if the tip is aligned with the mold cavity and the nozzle body is permitted to move or slide relative to the tip during thermal expansion of the nozzle. 
     SUMMARY 
     Embodiments hereof are directed towards a side-gate hot runner system, and a side-gate nozzle having a nozzle body, a nozzle tip and a transfer member. The nozzle body includes a heater, a nozzle channel extending longitudinally into the nozzle body, and a bore extending from an exterior side wall of the nozzle body to the nozzle channel. The nozzle tip includes a tip member, a tip channel extending through the tip member, and a sealing member in which the tip member is received. The transfer member is seated against a step in the bore in the nozzle body, the transfer member includes a bearing surface against which an abutment surface of the nozzle tip is slidably seated and a transfer channel extending therethrough which is in fluid communication between the nozzle channel and the tip channel. In operation thermal expansion of the transfer member along its length applies a sealing force against the abutment surface of the nozzle tip. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing and other features and advantages of the invention will be apparent from the following description of embodiments thereof as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG. 1  is a sectional view of a side-gate hot runner injection molding apparatus having a side-gate hot runner system and a side-gate hot runner nozzle assembly in accordance with an embodiment of the present application. 
         FIG. 2  is an enlarged view of a portion  2  of  FIG. 1 . 
         FIG. 3  is an enlarged view of a portion  3  of  FIG. 2 . 
         FIG. 4  is a sectional view of a side-gate tip assembly in accordance with an embodiment of the present application. 
         FIG. 5  is an enlarged view of a portion  5  of  FIG. 1  showing a cavity member, with a tip assembly installed therein, removed from the injection molding apparatus. 
         FIG. 6  is an enlarged view of portion  3  of  FIG. 2  showing a downstream end of a side-gate nozzle in accordance with another embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. In the following description, “downstream” is used with reference to the direction of mold material flow from an injection unit of an injection molding machine to a mold cavity of a mold of an injection molding system, and also with reference to the order of components or features thereof through which the mold material flows from the injection unit to the mold cavity, whereas “upstream” is used with reference to the opposite direction. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding field, background, summary or the following detailed description. 
       FIG. 1  is a sectional view of an injection molding apparatus  100  having a hot runner system  102  and a side-gate hot runner nozzle  104  in accordance with a non-limiting embodiment of the present application. Hot runner system  102  includes a manifold  106  and side-gate hot runner nozzle  104  which, for brevity is referred to as nozzle  104 . While two nozzles  104  are shown, injection molding apparatus  100  and hot runner system  102  can include other than two nozzles  104 . 
     Injection molding apparatus  100  includes a plurality of mold plates, for example, a first mold plate  108 A, a second mold plate  108 B, and a third mold plate  108 C (collectively referred to as mold plates  108 ) which form an enclosure  110  in which hot runner system  102  is received. Enclosure  110  includes a manifold chamber  112  which forms an insulating air gap around manifold  106  and a nozzle well  114  which forms an insulating air gap around nozzle  104 . Mold plates  108  typically include cooling channels, such as cooling channel  115  called out on first mold plate  108 A, through which cooling fluid is circulated to maintain injection molding apparatus  100  at a suitable molding temperature. Mold plates  108  are held together by fasteners (not shown), and may also include additional fastening/aligning components (not shown) such as guide pins, guide bushings etc. While three mold plates  108  are shown, injection molding apparatus  100  can include other than three mold plates  108 . 
     Manifold  106  includes a manifold channel  116  that extends therethrough. Manifold channel  116  includes a manifold inlet  118  at its upstream end for receiving moldable material from a source. At its downstream end, manifold channel  116  includes an outlet  120  which is in fluid communication with nozzle  104 . Manifold  106  further includes a manifold heater  121  for maintaining manifold  106  at a suitable processing temperature. Nozzle  104  delivers molding material to a mold cavity  122  that is located beside nozzle  104 . Mold cavity  122  is defined at least in part by a mold cavity component, such as a cavity insert  124  that is received in a bore  126  in first mold plate  108 A. 
     Referring to  FIG. 2 , which is an enlarged view of a portion  2  of  FIG. 1 , nozzle  104  includes a nozzle body  128 , a transfer member  130 , and a side-gate tip assembly  132 , which can be referred to as tip assembly  132 . Transfer member  130  is an intermediate component between nozzle  104  and tip assembly  132 . Nozzle body  128  includes a heater  134  extending around nozzle body  128  and a nozzle channel  136  that extends longitudinally into nozzle body  128  from an upstream end thereof. Nozzle channel  136  receives molding material from manifold channel via manifold outlet  120 . Nozzle body  128  further includes and a bore  138  that extends laterally from an exterior side wall  140  of nozzle body  128  to nozzle channel  136 . Although bore  138  is shown extending perpendicularly from a central axis A C  of nozzle body  128 , bore  138  can extend from central axis A C  at an angle between 90° and 150°. Heater  134  provides heat to nozzle body  128  for maintaining nozzle  104  at a suitable processing temperature. Heater  134  also heats transfer member  130 , which is received in bore  138  and is heated by way of contact with nozzle body  128 . To facilitate heat transfer from nozzle body  128  to transfer member  130 , transfer member  130  can be made from a material that is more thermally conductive than the material from which nozzle body  128  is made. An example of a suitable material for transfer member  130  includes a copper alloy. Examples of suitable materials for nozzle body  128  include H13 tool steel and 420 stainless steel. As shown, by way of example, heater  134  is a resistance wire heater that is embedded into nozzle body  128 . 
     Referring to  FIG. 3 , which is an enlarged view of a portion  3  of  FIG. 2 , transfer member  130  includes an extension portion  142 , a biasing portion  144  that extends radially outward from extension portion  142 . A transfer channel  146 , which is in fluid communication with nozzle channel  136 , extends through biasing portion  144  and extension portion  142 . Transfer member  130  further includes an external bearing surface  145  at a downstream end of transfer member  130  through which a sealing force F S  is applied to tip assembly  132 . 
     In the illustrated embodiment of  FIGS. 1-3 , transfer channel  146  includes a flared portion defined by an internal tapered surface  156  that expands radially outward in the upstream direction. In operation, melt pressure acts on internal tapered surface  156 , which urges transfer member  130  towards tip assembly  132  to promote a fluid seal between bearing surface  145  and an abutment surface  147  at the upstream end of tip assembly  132 . With transfer member  130  having internal tapered surface  156 , increasing injection pressure increases the force at which transfer member  130  is pushed towards tip assembly  132 . Melt pressure acting on internal tapered surface  156  can also expand extension portion  142  radially outward against bore  138  to promote a fluid seal between transfer member  130  and nozzle body  128  at the interface between extension portion  142  and bore  138 . 
     Bore  138  includes a first lateral portion  158  and a second lateral portion  160 . First lateral portion  158  is sized to receive extension portion  142  and second lateral portion  160  is sized to receive biasing portion  144 . The fit between first lateral portion  158  and extension portion  142 , and the fit between second lateral portion  160  and biasing portion  144  is sized to promote heat transfer from nozzle body  128  to transfer member  130  when injection molding apparatus  100  is in operation. Such fit can be a slide fit or other close fit which limits or prevents egress of molding material from between transfer member  130  and bore  138  when injection molding apparatus  100  is in operation, without impinging on longitudinal thermal expansion of transfer member  130 . A configuration as such also helps to support transfer member  130  within bore  138  when cavity insert  124  and tip assembly  132  received therein are removed from the remainder of injection molding apparatus  100 , for example to substitute tip assembly  132  with a replacement tip assembly  132 . Also, as shown in the illustrated embodiment of  FIGS. 1-3 , transfer member  130  includes a flange  162  at its downstream end which may be useful to facilitate handling of transfer member  130 , for example, during servicing of nozzle  104 . 
     Continuing with  FIG. 3 , bore  138  includes a step  164  in nozzle body  128  against which transfer member  130  is seated. As nozzle  104  is heated to a processing temperature, thermal expansion of nozzle body  128  across its width moves step  138  away from central axis A C , and as transfer member  130  and tip assembly  132  are heated they longitudinally expand away from central axis A C  towards mold cavity  122 . Thermal expansion of transfer member  130  against step  164  causes bearing surface  145  to press against abutment surface  147  of tip assembly  132  to promote a fluid seal between transfer member  130  and tip assembly  132 . Step  164  is located between first lateral portion  158  and second lateral portion  160 . Transfer member  130  includes a first shoulder  166  between extension portion  142  and biasing portion  144 . First shoulder  166  seats against step  164  such that lengthwise thermal expansion of transfer member  130  between first shoulder  166  and bearing surface  145  creates sealing force F S  against abutment surface  147 , which urges tip assembly  132  away from nozzle body  128  and towards cavity insert  124 . Sealing force F S  increases with an increase in the temperature of transfer member  132 . Sealing force F S  when nozzle  104  is heated is also increased by increasing the cold condition length of transfer member  130  between first shoulder  166  and bearing surface  145 . To assist in creating sealing force between transfer member  130  and tip assembly  132 , transfer member  130  can be made from a material that has a greater coefficient of thermal expansion than the material from which nozzle body  128  is made. 
     Transfer member  130  further includes a second shoulder  168  between biasing portion  144  and flange  162 . The longitudinal distance D 1  between first shoulder  166  and second shoulder  168  is greater than the longitudinal distance D 2  between step  164  in bore  138  and side wall  140  of nozzle body  128  where side wall  140  is overlapped by flange  162 . In this configuration, when first shoulder  166  is seated against step  164 , flange  162  is separated from side wall  140  by a gap G 1  in which a tool may be inserted to assist with extracting transfer member  130  from bore  138 , for example, if transfer member  130  requires servicing or replacing. Gap G 1  also ensures first shoulder  166  is seated against step  164  rather than second shoulder  168  being seated against side wall  140 . 
     As shown in in the illustrated embodiment of  FIGS. 1-3 , step  164  is perpendicular to first lateral portion  158  and second lateral portion  160 , and first shoulder  166  is perpendicular to extension portion  142  and biasing portion  144 . In this configuration, step  164  and first shoulder  166  are parallel to each other and perpendicular to the longitudinal thermal expansion direction of transfer member  130  which helps to promote sealing force between transfer member  130  and tip assembly  132 . 
     Continuing with  FIG. 3  and referring to  FIG. 4 , which is a sectional view of tip assembly  132  in accordance with an embodiment of the present application. Tip assembly  132  receives molding material from transfer member  130  and delivers molding material to mold cavity  122 . Tip assembly  132  includes a tip member  148 , which is heated by way of contact with transfer member  130 , and a sealing member  172  in which tip member  148  is received. Tip member  148  includes a tip channel  154  that extends through tip assembly  132  and is in fluid communication between transfer channel  146  and mold cavity  122 . Abutment surface  147  of tip assembly  132  includes the upstream end of tip member  148 . To facilitate heat transfer from transfer member  130  to tip member  148 , tip member  148  can be made from a material having a thermal conductivity that is equal to or more than that of the material from which sealing member  172  is made. Examples of suitable materials for tip member  148  include a copper alloy and TZM molybdenum alloy. Examples of suitable materials for sealing member include H13 tool steel and a titanium alloy. Tip member  148  includes a tip member head  173  that seats against sealing member  172 . In the illustrated embodiment of tip assembly  132 , head  173  seats against a corresponding step  175  in the upstream end of sealing member  172 . As tip member  148  is heated, tip member head  173  expands rearward from step  175  and against transfer member  130 . To improve the sealing force between tip member  148  and transfer member  130 , tip member  148  can be made from a material that has a greater coefficient of thermal expansion than that of the material from which sealing member  172  is made so that a thickness of tip member head  173  expands more than a depth of step  175 . 
     Sealing member  172  includes a tubular portion  150  that surrounds tip member  148  and is received in a bore  174  in cavity insert  124 . Tubular portion  150  includes a sealing surface  176  that forms a circumferential seal with bore  174 . Sealing surface  176  can also align tip assembly  132  with mold cavity  122 . Engagement between sealing surface  176  and bore  174  can be a slide fit, a light press-fit or an interference fit which can help couple tip assembly  132  to cavity insert  124 . Alternatively, tip assembly  132  can be secured to cavity insert  124  by, for example, a separate retention member or a threaded connection therebetween. Sealing member  172  further includes a bracing surface  178  surrounding tubular portion  150  which is transverse to sealing surface  176 . Bracing surface  178  is upstream from sealing surface  176  and supports tip assembly  132  against cavity insert  124  when thermal expansion of transfer member  130  applies sealing force F S  against abutment surface  147 . Bracing surface  178  optionally forms a face seal around bore  174  in cavity insert  124 . In the illustrated embodiments shown herein, bracing surface  178  is the downstream end of a flange  152  that surrounds tubular portion  150 . 
     In the illustrated embodiment of  FIGS. 1-3 , bearing surface  145  of transfer member  130  and abutment surface  147  of tip assembly  132  are parallel planar surfaces. This configuration allows transfer member  130 , received in nozzle body  128 , to move or slide relative to tip assembly  132  during longitudinal thermal longitudinal expansion of nozzle body  128 , and also allows tip assembly  132  to be displaced laterally (downward in the page views of  FIGS. 1-3 ) relative to transfer member  130  when cavity insert  124  having tip assembly  132  installed therein is removed from an otherwise assembled injection molding apparatus  100 , for example as discussed below with regard to  FIG. 5 . 
     Referring now to  FIG. 5  which is an enlarged view of a portion  5  of  FIG. 1  showing cavity insert  124 , with tip assembly  132  installed therein, removed from injection molding apparatus  100 . To facilitate servicing or replacement of tip assembly  132  and/or transfer member  130 , cavity insert  124  is extracted from bore  126  in first mold plate  108 A in the direction E 1 . Tip assembly  132 , which is received in cavity insert  124 , travels with cavity insert  124  as it is extracted. While cavity insert is being extracted, flange  152  supports tip assembly  132  against lateral tipping. Closely sizing bore  138  and portions of transfer member  130  received therein not only promotes heat transfer from nozzle body  128  to transfer member  130 , it also helps to support transfer member  130  against side loading within bore  138  as cavity insert  124  and tip assembly  132  received therein are removed from first mold plate  108 A. Transfer member  130  projects beyond side wall  140 , such that bearing surface  145  is located beside and spaced apart from sidewall  140  of nozzle body  128  by a gap G 2 . This configuration allows cavity insert  124  and tip assembly  132  received therein to be slidably separated (i.e. displaced downward in the direction E 1 ) from transfer member  130 , without interfering with nozzle body  128 . 
     With cavity insert  124  extracted from first mold plate  108 A, tip assembly  132  can be extracted from cavity insert  124  as shown by arrow E 2 . With cavity insert  124  removed from first mold plate  108 A, transfer member  130  can be extracted from bore  138  in nozzle body  128  as shown by arrow E 3 . 
     Referring now to  FIG. 6 , which is an enlarged view of portion  3  of  FIG. 2  showing a downstream end of a nozzle  104   a  in accordance with another embodiment of the present application. Nozzle  104   a  includes a transfer member  130   a  having an extension portion  142   a  and a biasing portion  144   a . Unlike transfer member  130  in the illustrated embodiments of  FIGS. 1-3 , transfer member  130   a , does not include a flange or a second shoulder formed thereby as does transfer member  130  in the illustrated embodiments of  FIGS. 1-3 . 
     A nozzle body  128   a  of nozzle  104   a  includes a bore  138   a  having a first lateral portion  158   a  sized to receive extension portion  142   a  and a second lateral portion  160   a  sized to receive biasing portion  144   a . Bore  138   a  includes a step  164   a  between first lateral portion  158   a  and second lateral portion  160   a , and transfer member  130   a  includes a shoulder  166   a  between extension portion  142   a  and biasing portion  144   a . Transfer member  130   a  is seated against step  164   a  and lengthwise thermal expansion of transfer member  130   a  urges tip assembly  132  away from nozzle body  128   a , towards cavity insert,  124 , to apply a sealing force F S  against abutment surface  147  of tip assembly  132 . 
     In comparison to the illustrated embodiment of  FIGS. 1-3 , the surface area of bearing surface  145  is equal to or substantially equal to that of bearing surface  145   a  in  FIG. 6 ; however, since transfer member  130   a  lacks a flange, shoulder  166   a  and step  164   a  each have a larger surface area than shoulder  166  and step  164  of the illustrated embodiment of  FIGS. 1-3 . The larger surface areas of step  164   a  and shoulder  166   a  increases the overall interface area between transfer member  130   a  and bore  138   a  which may improve heat transfer between nozzle body  128   a  and transfer member  130   a  while maintaining the size of bearing surface  145   a.    
     The longitudinal distance D 3  between shoulder  166   a  and bearing surface  145   a  is greater than the longitudinal distance D 2  between step  164   a  and side wall  140   a  of nozzle body  128   a . In this configuration transfer member  130   a  projects beyond side wall  140   a , such that bearing surface  145   a  is located beside and spaced apart from nozzle body  128   a . Similar to the embodiment described with regard to  FIGS. 1-3 , this configuration allows cavity insert  124  and tip assembly  132  received therein to be separated (i.e. displaced downward as shown on the pageview of  FIG. 6 ) from transfer member  130   a , for example, to facilitate maintenance such as replacing a tip assembly  132 , without interfering with nozzle body  128   a.    
     Although bore  138 , transfer member  130  and tip assembly  132  are described in singular form, as shown in the illustrated embodiments, nozzle  104  includes a plurality of bores  138  that extend outward from nozzle channel  136  and through nozzle body  128 , each bore  138  having a respective transfer member  130  seated therein to apply sealing force against a respective tip assembly  132 . The plurality of bores  138 , are angularly spaced evenly around nozzle body  128  to counteract thermal expansion forces oppositely facing transfer members  130  against their respective tip assembly  132  and its associated cavity insert  124 . Alternatively, nozzle  104  can include a single bore  138 , transfer member  130 , and tip assembly  132 . In this configuration, a spacer (not shown) is positioned on the opposite side of nozzle body  128  from bore  138 , between nozzle body  128  and a mold component to counter act thermal expansion forces experienced by transfer member  130  against its tip assembly  132  and its associated cavity insert  124 . 
     In the illustrated embodiments shown herein side wall  140  of nozzle body  128  from which bore  138  extends is a planar side surface of nozzle body  128 . This configuration can reduce the width of nozzle body  128  in the area surrounding bore  138 , which can reduce the tip-to-tip spacing of an oppositely facing pair of tip assemblies  132 . 
     While various embodiments have been described above, they have been presented only as illustrations and examples of the present invention, and not by way of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments but should be defined only in accordance with the appended claims and their equivalents. It will also be understood that features of each embodiment discussed herein can be used in combination with the features of other embodiments.