WO2002045938A1

WO2002045938A1 - Flow deflector apparatus and method of using it

Info

Publication number: WO2002045938A1
Application number: PCT/CA2001/001578
Authority: WO
Inventors: Abdeslam Bouti
Original assignee: Husky Injection Molding Systems Ltd.
Priority date: 2000-12-08
Filing date: 2001-11-07
Publication date: 2002-06-13
Also published as: CA2430649C; EP1341660A1; US20020081348A1; CA2430649A1; US6524093B2; JP2004520189A; JP4516271B2; AU2002223322A1

Abstract

A flow deflector apparatus and method in an injection molding system which transitions a flowing medium around an obstruction (12), said flowing medium exhibiting reduced stagnation points and substantially uniform flow characteristics downstream of the obstruction (12).

Description

FLOW DEFECTOR APPARATUS AND METHOD OF USING IT TECHNICAL FIELD

This invention relates to an apparatus and method for converting the circular flow inside a melt channel to a uniform annular flow. More specifically, this invention relates to an apparatus and method for improving uniform melt flow and elimination of stagnation points as it passes through an injection molding machine and/or hot runner system.

BACKGROUND OF THE INVENTION

The large number of variables in the injection molding process creates serious challenges to creating a uniform and high quality part. These variables are significantly compounded within multi-cavity molds. Here we have the problem of not only shot to shot variations but also variations existing between individual cavities within a given shot. Shear induced flow imbalances occur in all multi-cavity molds that use the industry standard multiple cavity "naturally balanced" runner system whereby the shear and thermal history within each mold is thought to be kept equal regardless of which hot-runner path is taken by the molten material as it flows to the mold cavities. These flow imbalances have been found to be significant and may be the largest contributor to product variation in multi-cavity molds.

Despite the geometrical balance, in what has traditionally been referred to as "naturally balanced" runner systems, it has been found that these runner systems can induce a significant variation in the melt conditions delivered to the various cavities within a multi-cavity mold. These variations can include melt temperature, pressure, and material properties. Within a multi-cavity mold, this will result in variations in the size, shape and mechanical properties of the product.

It is well known that providing for smooth flow of pressurized melt is critical to successful molding of certain materials. Sharp bends, corners or dead spots in the melt passage results in unacceptable residence time for some portion of the melt being processed which can cause too much delay on color changes and/or result in decomposition of some materials or pigments of some materials such as polyvinyl chloride and some polyesters or other high temperature crystalline materials. In most multi- cavity valve gated injection molding systems it is necessary for the melt flow passage to change direction by 90° and to join the bore around the reciprocating valve stem as it extends from the manifold to each nozzle.

These problems necessarily require fine tolerance machining to overcome and it is well known to facilitate this by providing a separate bushing seated in the nozzle as disclosed in U.S. Pat. No. 4,026,518 to Gellert. A similar arrangement for multi- cavity molding is shown in U.S. Pat. No . 4,521,179 to Gellert. U.S. Pat. No . 4,433,969 to Gellert also shows a multi-cavity arrangement in which the bushing is located between the manifold and the nozzle. Also shown in U.S. Pat. No . 4,705,473 to Schmidt, provides a bushing in which the melt duct in the bushing splits into two smoothly curved arms which connect to opposite sides of the valve member bore. U.S. Pat. No . 4,740,151 to Schmidt, et al . shows a multi-cavity system with a different sealing and retaining bushing having a flanged portion mounted between the manifold and the back plate.

U.S. Patent No. 4,443,178 to Fujita discloses a simple chamfered surface located behind the valve stem for promoting the elimination of the stagnation point which would otherwise form.

U.S. Patent No. 4,932,858 to Gellert shows a separate bushing seated between the manifold and the injection nozzle in the melt stream which comprises a melt duct with two smoothly curved arms which connect between the melt passage in the manifold and the melt passage around the valve stem in an effort to eliminate the stagnation points.

Another valve nozzle device has also been known, the device having a number of valve nozzles as shown in FIGS. 7 and 8. The plastic resin is passed through a first passageway 30 and then passed through a second passage 30a extending substantially at right angles with respect to the first passage 30 into valve chambers and then injected into metal molds through nozzles (not shown) . Needle valve 32 is provided adjacent to the nozzle.

With the above described construction of the conventional multi-valve nozzle device, since the second passage 30a extending substantially at right angles with respect to the first passage 30 is in a plane including the needle valve 32, resin is caused to stagnate at positions Pi and P2 as shown in FIGS. 7 and 8. The stagnation of the plastic resin causes a pressure loss in each valve chamber as well as inhibits color change and uniform melt velocity. Although the stagnation of the plastic resin may be more or less reduced by the application of the prior art, heretofore the complete elimination of the stagnation or and resulting non-uniform annular flow has been impossible.

Reference should also be made to the following references: "Analysis for Extrusion Die Design" by B. Proctor, SPE ANTEC, Washington, D.C. pages 211-218 (1971); and "Extrusion Dies for Plastics and Rubber" by W. Michaeli, Carl Hanser Verlag, Munich, ISBN 3-446-16190-2 (1992) .

Reference should also be made to the following reference: "Extrusion Dies for Plastics and Rubber" by W. Michaeli, Carl Hanser Verlag, Munich, ISBN 3-446-16190-2 (1992).

There exists a need for a method and apparatus that substantially reduces the flow imbalances and stagnation points in an injection molding system and/or hot runner system that occurs as a result of the flow being diverted around a melt flow obstruction such as a valve stem, a nozzle, a nozzle tip, a valve stem guide, a torpedo, etc.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a flow deflector in a melt channel that creates a substantially uniform annular flow velocity profile.

Another object of the present invention is to provide a flow deflector in a melt channel that eliminates stagnation points in the channel that occurs when the melt flows around an obstruction in the channel.

A further object of the present invention is to provide a means for fast color change-over in an injection molding system, thereby reducing machine downtime between color changes .

Still another object of the present invention is to provide a means for conveying heat sensitive materials through an injection molding system with reduced degradation caused by stagnation points in the melt stream.

Yet another object of the present invention is to provide substantially uniform annular flow to the mold cavity which leads to improved part quality.

Still yet another object of the present invention is to provide improved valve stem guidance and support in an injection molding machine/hot runner system, thereby resulting in a higher quality molded part and a valve stem with a longer usable life.

Yet another object of the present invention is to provide an improved, cost effective means for turning the melt flow through various angles as it flows from the machine to a mold cavity.

Even still another object of the present invention is to provide a co-injection nozzle that exhibits improved part quality due to the elimination of stagnation points that occur as the melt flows around the valve stem or other flow obstruction.

The foregoing objects are achieved by providing a flow deflector in a melt channel, preferably around a valve stem or other flow obstruction, where the melt flow is converted from circular flow to annular flow. The deflector comprises a cylindrical body with a gradually expanding channel disposed on its outer surface. The channel is such that a first and second wall of the groove form two symmetrical inverted funnel-shaped cavities as the melt travels down the cylindrical body. The walls of the channel are designed to have substantially the same length in the direction the melt travels. In this arrangement, the melt flow is constricted on the near side of the flow as it travels around the cylindrical body which in turn promotes the flow around the back of the cylindrical body. Promoting the flow around the back of the cylindrical body helps to "wash-out" any stagnation points whilst also promoting a uniform annular flow rate as the melt exits the large end of the groove .

One preferred embodiment comprises a cylindrical body with a gradually constricting channel disposed on its outer surface. The channel is formed to be decreasing in depth and width, so as the melt flows into the channel, it gradually spills out of the channel. The gradual restriction of the channel helps direct the melt around the back of the cylindrical body which helps to eliminate stagnation points behind the flow obstruction while also providing uniform annular flow of the melt .

Further objections and advantages of the present invention will appear hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and la are simplified views showing the basic principle of a side-fed mandrel die;

FIG. 2 is a partial sectional view of a preferred embodiment of the present invention in a co-injection hot runner nozzle;

FIG. 2a is a simplified isometric view of a preferred embodiment of the present invention;

FIG. 2b is a partial sectional view of another preferred embodiment of the present invention in a co-injection nozzle comprising two melt flow inlets;

FIG. 3 is a sectional view of another preferred embodiment of the present invention comprising a valve-gated nozzle in an injection molding system;

FIG. 4 is a sectional view of another preferred embodiment of the present invention comprising a valve-gated nozzle assembly;

FIG. 5 is a sectional view of another preferred embodiment of the present invention comprising a nozzle tip assembly of a hot runner nozzle;

FIGS. 6 and 6a are sectional views of another preferred embodiment of the present invention comprising a nozzle tip with two melt flow inlets;

FIGS. 7 and 8 are sectional views of the prior art exhibiting stagnation points and non-uniform annular flow rates;

FIG. 9 is a partial sectional view of another preferred embodiment of the present invention comprising an injection nozzle assembly having a tapered surface.

FIG. 10 is a simplified view showing the basic principle of a coat-hanger manifold;

FIG. 11 is a partial sectional view of a preferred embodiment of the present invention in a co-injection hot runner nozzle;

FIG. 11a is a simplified isometric view of a preferred embodiment of the present invention;

FIG. lib is a partial sectional view of another preferred embodiment of the present invention in a co-injection nozzle comprising two melt flow inlets;

FIG. 12 is a sectional view of another preferred embodiment of the present invention comprising a valve-gated nozzle in an injection molding system;

FIG. 13 is a sectional view of another preferred embodiment of the present invention comprising a valve-gated nozzle assembly;

FIG. 14 is a cross-sectional view of another preferred embodiment of the present invention comprising a nozzle tip assembly of a hot runner nozzle;

FIG. 15 is a partial cross-sectional view of another preferred embodiment of the present invention comprising a nozzle tip with two melt flow inlets;

FIGS. 16a and 16b are partial cross-sectional views of the flow deflector in accordance with the present invention;

FIGS. 17 is a partial cross-sectional view of the flow deflector in accordance with a preferred embodiment of the present invention;

FIG. 18 is a partial sectional view of another preferred embodiment of the present invention comprising an injection nozzle assembly having a tapered surface;

FIG. 19 is a partial sectional view of another preferred embodiment of the present invention comprising a flow deflector formed in a bushing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring first to FIGS. 1 and la, a simplified flat construction is shown which depicts the basic principles behind the present invention. Similar to side fed mandrel die principles, the melt flow will enter at a predetermined angle to a flow deflector 10 at a flow inlet 18. The melt flow will split and travel around a torpedo 12 and between a torpedo wall 14 and an outside wall 16, the cavity therein forming an inverted funnel channel 19. Funnel channel 19 is defined by a constriction 20 adjacent flow inlet 18 which increases in cross-section as the flow travels towards an exit 17 of funnel channel 19. As shown in FIG. la, a pair of balanced cavities 22 exhibiting equal cross-sectional area is formed on the sides of torpedo 12. In an effort to create a uniform flow rate v as the melt reaches exit 17, the length of torpedo wall 14 (shown as L2) and outside wall 16 (shown as Ll) are substantially equal.

Now referring to FIGS. 2, 2a and 2b, a co-injection hot runner nozzle 11 according to a preferred embodiment of the present invention is generally shown. This preferred embodiment is comprised of the device as shown in FIG. 1, which has been wrapped around the circumference of a deflector body 26. Deflector body 26 is inserted into a nozzle body 24 and aligned with a second melt passage 30 such that the melt enters the flow inlet 18 substantially perpendicular to deflector body 26. This alignment is fixed by a locating pin 34. Locating pin 34 could be any suitable alignment means known in the art including (but not limited to) screws, rivets, spring pins, dowel pins, etc. Deflector body 26 further comprises a first melt passage 28 which is aligned with second melt passage 30 for communication of a first melt from an injection molding machine (not shown) or hot runner manifold (also not shown) .

A valve stem 32 extends through a third melt passage 33 that is located inside of and runs the length of deflector body 26. Third melt passage 33 is provided to communicate the flow of a second melt into the mold cavity. Valve stem 32, as well known in the art, is selectively positioned through an up and down motion to start and stop the flow of the two melt streams through a nozzle outlet 36, thereby controlling the filling of the mold cavity. In this arrangement, popularly known as co- injection, a mold cavity may be filled with two or more different melts for effects such as multiple colors, different melt materials and the like.

As the melt flows from second melt passage 30 to flow inlet 18, it strikes the outside wall of the deflector body 26 substantially perpendicular to valve stem 32 longitudinal axis (However, non-perpendicular flow impingement could easily be accomplished) . If torpedo 12 and outside wall 16 were not present, the melt would tend to flow down along the face of deflector body 26 closest to flow inlet 18, thereby causing stagnation points behind deflector body 26. However, in this preferred embodiment, the melt flow impinges on torpedo wall 14 and outside wall 16 thereby causing the flow to be diverted through funnel channel 19 and around the back of deflector body 26.

In addition, torpedo wall 14 and outside wall 16 are provided with substantially the same length, which causes the melt to flow substantially an equal distance as it travels along deflector body 26. By the time the melt reaches exit 17, the flow rate of the melt is essentially equal, thereby resulting in uniform annular flow of the melt.

In FIG. 2b, a dual inlet co-injection nozzle similar to that shown in FIG. 2 is shown. The significant difference between these two preferred embodiments is the use of an additional first melt passage 28a that is diametrically opposed to the other first melt passageway. In this embodiment, an identical torpedo 12a and outside wall 16a are provided which defines an identical and second funnel channel 19a. In this arrangement, elimination of stagnation points and the creation of a uniform annular velocity is achieved.

Referring to FIG. 3 (where like features have like numerals) , another preferred embodiment in accordance with the present invention is generally shown. A hot runner valve gate system 100 for injecting plastic material into a mold or the like is illustrated. The system includes a backing plate 102 and a manifold plate 104. The system further includes a nozzle assembly 108 for introducing molten plastic material into a mold (not shown) and a manifold/bushing arrangement 110 for allowing communication of plastic material from a source (not shown) to the nozzle assembly 108. A manifold heater 139 is shown inserted in a manifold 138, thereby heating the manifold 138 which in turn heats the flowing plastic within a melt channel 142 and a deflector housing channel 144.

As shown in FIG. 3, the nozzle assembly 108 consists of a nozzle body 112, a tip 114, a nozzle heater 116, a spring means 118, and a nozzle insulator 113. The nozzle body 112 is typically made of steel, while the tip 114 may be formed from any suitable highly heat-conductive material known in the art such as beryllium/copper . The nozzle body 112 has an axial channel 120 through which molten plastic material flows. The tip 114 surrounds a terminal part of the axial channel 120.

If desired, the nozzle tip 114 may include a sheath 122 for thermally insulating the downstream end of the nozzle tip 114.

The sheath 122 may be formed from a resinous material which may be prefabricated. Alternatively, the sheath 122 may be formed from an overflow of injected resin in the first operating cycle or cycles. The nozzle insulator 113 is installed within a cavity of the manifold plate 104 and acts to reduce the thermal communication between the nozzle body 112 and the manifold plate 104, thereby maintaining the high temperature of the molten plastic material as it flows through the axial channel

120. The nozzle insulator 113 may be formed from any suitable insulating material, typically known in the art such as titanium.

The nozzle heater 116 may be any suitable electric heater known in the art to which current is admitted by way of a cable 124. As shown in FIG. 3, the nozzle heater 116 surrounds a portion of the nozzle body 112.

A valve stem 126 is provided to permit opening and closing of the gate 128 in the nozzle body 112. The valve stem 126 may be formed by a steel rod that extends through a passageway in the deflector housing 130 and into the nozzle body 112. The end of the valve stem 126 opposite to the gate 128 is connected to a piston head 131 by a set-screw 154.

The piston head 131 is housed within a cylinder housing which comprises the upper distal end of deflector housing 130 and formed by cylindrical wall 134. Downstroke of the piston head

131 causes the valve stem 126 to move into a position where it closes or reduces the cross sectional area of the gate 128 so as to restrict flow of the molten plastic material. Upstroke of the piston head 131 causes the valve stem 126 to move so as to increase flow of the molten plastic material through the gate 128.

The hot runner system of this preferred embodiment also includes a manifold/deflector housing arrangement 110 consisting of the manifold 138 and the deflector housing 130 inserted therein. A locating pin 129 fixes the alignment of the deflector housing 130 to the melt channel 142. The manifold 138 is formed by a distribution plate housed between the plates 102 and 104 but separated therefrom by an air gap 140. The backing plate 102 is rigidly affixed to the manifold plate 104 by a plurality of high strength bolts (not shown) which must withstand the large tensile forces generated during the cyclic molding process.

The manifold includes the melt channel 142 forming part of the hot runner system for transporting molten plastic material from a source (not shown) to the gate 128 associated with a respective mold or molds. The manifold further includes a bore 143 into which deflector housing 130 is inserted. The manifold 138 may be formed from any suitable metal or heat conducting material known in the art. The manifold heater 139 is well known in the art and typically comprises a wire/ceramic resistive type heater with a cylindrical cross section that is seated into a groove of the manifold 138.

The deflector housing 130 guides a portion of the valve stem 126. This is an important advantage of the present invention because this increased valve stem support reduces valve stem wear and will significantly increase the life of the valve stem. Increased valve stem life will result in reduced maintenance costs and machine downtime.

The deflector housing 130 is formed from any suitable material known in the art (usually steel) and is designed to be inserted into the manifold 138 from the top. As shown in FIG. 3, the deflector housing channel 144 mates with the melt channel 142 in the manifold 138 and the axial channel 120 in the nozzle assembly 108. Similar to the embodiments already discussed, the deflector housing 130 further comprises a torpedo 12 and an outside wall 16 which acts to divert the flow around the corner and behind the valve stem 126. The melt flow enters the deflector housing channel 144 and is immediately diverted between the torpedo 12 and the outside wall 16 which is shaped to form an inverted funnel channel 19. The torpedo wall 14 is designed to have substantially the same length as outside wall 16 so that by the time the melt reaches exit 17, the melt flow exhibits a substantially uniform annular flow velocity. In this arrangement, the melt navigates both a 90 degree change in direction and splits around an obstacle, for example the valve stem 126 or the deflector housing 130, without creating flow imbalances that adversely affect the molded part quality. In addition, stagnation points, which normally form behind valve stem 126, have been eliminated by directing the melt to flow around to the back of the valve stem 126.

It should be noted that even though the preceding embodiments describe a deflector housing 26 (FIG. 2) that is separate from the nozzle body 24 (FIG. 2) , a single bushing could easily be fabricated that incorporates all the required features.

Referring now to FIG. 4 (where like features have like numerals) , another preferred embodiment in accordance with the present invention is generally shown. In this embodiment, the deflector body 26 is a singular bushing that is inserted in the nozzle body 24 for a single-melt nozzle.

Here again, the valve stem 32 is inserted through the deflector body 26, thereby supporting and guiding the valve stem 32 while also directing the melt around the back of the valve stem. Similar to the previous embodiments, melt flows from melt channel 142 through the first melt passage 28 which is located in the upper flange of the deflector body 26. Alignment between melt channel 142 and first melt passage 28 is maintained by locating pin 34. The melt then flows through second melt passage 30 which is located inside nozzle body 24. The melt is then directed against deflector body 26 where the flow is diverted around to the back of the valve stem 32 by outside wall 16 and torpedo wall 14. The melt flow is diverted through the funnel channel 19 such that when it exits from the deflector body 26, it has been transformed from circular flow to uniform annular flow which exits nozzle outlet 36 to form a high quality, homogeneous molded part.

Referring now to FIGS. 5, 6 and 6a, (where like features have like numerals) another preferred embodiment of the present invention is shown comprising an injection molding nozzle tip assembly 200. In this embodiment, the principles of side fed mandrel dies previously discussed have been applied to the tip of an injection nozzle assembly. Commonly referred to as a "hot tip", this preferred embodiment comprises a nozzle without the valve stem as shown in the previous embodiments.

An elongated first melt passage 28 is located in a sleeve 40 for the communication of a melt to a tip 44. The sleeve 40 is rigidly affixed inside the nozzle body 24 and traps the tip 44 co-axially in the nozzle body 24. In the preferred embodiment, the sleeve is threaded into the nozzle body 24 and abuts against a top flange of tip 44. A heater 116 is wrapped around the outside of nozzle body 24 for maintaining the temperature of the melt as it flows through the nozzle assembly.

Melt flows through first melt passage 28 and is further communicated to flow inlet 18 through a tip passage 46. The flow is thus diverted around torpedo 12 and through funnel channel 19 as further defined by outside wall 16. In this arrangement, the melt flow exits nozzle outlet 36 as a uniform annular flow. Elimination of stagnation points behind the tip 44 is accomplished by forcing the melt to flow around to the back of the tip 44.

Referring to FIG. 6, a nozzle assembly similar to FIG. 5 is shown, except for the addition of a second tip passage 46 which communicates the melt flow to two sides of the tip 44. In addition, a second symmetrical torpedo 12 and outside wall 16 are provided to define a second funnel channel 19. In FIG. 6a another preferred embodiment is shown which also has two tip passages 46 for the communication of a melt to tip 44. However, in this embodiment, the torpedo 12 has been removed. This arrangement may be advantageous for less demanding applications due to its lower cost to fabricate.

Referring now to FIG. 9 (where like features have like numerals) , another preferred embodiment of the present invention is shown which comprises a deflector body 26 which has a tapered flow surface. Side fed mandrel die principles have shown that a tapered flow surface, especially in the area of the funnel channel 19, helps to substantially reduce the pressure drop that occurs in the melt as it is diverted around a flow obstruction. Torpedo 12 and outside wall 16 are formed parallel to the tapered surface which comprises the funnel channel 19. The tapered deflector body 26 is inserted into a tapered receiving hole in the manifold 138, and alignment is maintained by the abutting tapered surfaces. A locating pin, similar to that shown in previous embodiments may also be used to further maintain the deflector body 26 alignment with the melt channel 142.

This tapered channel arrangement could also be utilized in the aforementioned embodiments. Specifically, the embodiments shown in FIGS. 2, 2b, 3, 4, 5, 6 and 6a could all incorporate the use of the tapered flow surface to reduce the melt pressure drop as it flows around obstacles.

While the previous embodiments all show the use of the torpedo 12 and outside wall 16 as part of a deflector body 26 that is wrapped around a valve stem 32, the torpedo 12 and outside wall 16 could easily be placed directly on the outside surface of the valve stem 32. A disadvantage to this approach however is the reduction in the valve stem support provided by the deflector housing that may lead to accelerated wear of the valve stem. In addition to this drawback, it would also be necessary to incorporate an alignment feature to maintain alignment of the valve stem with the manifold channel. Referring now to FIG. 10, a simplified flat construction is shown which depicts the basic principles behind the present invention. Similar to coat hanger manifold principles well known in the extrusion arts, the melt flow will enter at a predetermined angle to a channel 319 at a flow inlet 318. The melt will then split and flow equally down each side of the symmetrical channel 319 till it reaches an end 316 of the channel. The channel 319 is formed to have a decreasing cross section so as the melt travels down the channel 319, more and more of the melt will spill over and out of the channel 319 into annular area 320 toward exit 317. In this arrangement, the melt will reach exit 317 exhibiting substantially uniform flow v as shown by the arrows on the figure. In order to maintain a constant pressure drop as the melt travels through the channel 319, the volumetric flow rate in the channel 319 from the inlet 318 to the end 316 must fall off to zero in a linear fashion. To maintain uniform volumetric flow, annular area 320 is defined by a uniform cross-sectional area along its longitudinal axis.

Now referring to FIGS. 11, 11A and 11B, a co-injection hot runner nozzle 311 according to a preferred embodiment of the present invention is generally shown. This preferred embodiment is comprised of the device as shown in FIG. 10, which has been wrapped around the circumference of a deflector body 326. Deflector body 326 is concentric to and inserted into a nozzle body 324 and aligned with a second melt passage 330 such that the melt enters the flow inlet 318 substantially perpendicular to deflector body 326. This alignment is fixed by a locating pin 334. Locating pin 334 could be any suitable alignment means known in the art including (but not limited to) screws, rivets, spring pins, dowel pins, etc. Deflector body 326 further comprises a first melt passage 328 which is aligned with second melt passage 330 for communication of a first melt from an injection molding machine (not shown) or hot runner manifold (also not shown) .

A valve stem 332 extends through a third melt passage 333 that is located inside of and runs the length of deflector body 326. Third melt passage 333 is provided to communicate the flow of a second melt into the mold cavity. Valve stem 332, as well known in the art, is selectively positioned through an up and down motion to start and stop the flow of the two melt streams through a nozzle outlet 336, thereby controlling the filling of the mold cavity. In this arrangement, popularly known as co- injection, a mold cavity may be filled with two or more different melts for effects such as multiple colors, different melt materials and the like.

As the melt flows from second melt passage 330 to flow inlet 318, it strikes the outside wall of the deflector body 326 substantially perpendicular to valve stem 332 longitudinal axis (However, non-perpendicular flow impingement could easily be accomplished) . If channel 319 was not present, the melt would tend to flow down along the face of deflector body 326 closest to flow inlet 318, thereby causing stagnation points behind deflector body 326. However, in this preferred embodiment, the melt flows into channel 319 and is directed to flow around the deflector body 326, thereby eliminating the formation of stagnation points. As the melt flows through channel 319, the depth and width of the channel decreases so as to force more and more of the melt out of the channel 319. This gradually transitions the flow to annular flow through annular area 320 which has a uniform cross-section so that by the time the melt reaches the exit 317, a uniform velocity profile has been established which results in the formation of a high quality molded part .

In FIG. 11B, a dual inlet co-injection nozzle similar to that shown in FIG. 11 is shown. The significant difference between these two preferred embodiments is the use of an additional first melt passage 328a that is diametrically opposed to the other first melt passageway. It should be noted that the melt channels are not required to be diametrically opposed. In this embodiment, identical channels 319 and 319a are provided. In this arrangement, elimination of stagnation points and the creation of a uniform annular velocity is also achieved.

Referring to FIG. 12 (where like features have like numerals) , another preferred embodiment in accordance with the present invention is generally shown. A hot runner valve gate system 400 for injecting plastic material into a mold or the like is illustrated. The system includes a backing plate 402 and a manifold plate 404. A mold base 406 is further attached to the 5 manifold plate 404.

The system further includes a nozzle assembly 408 for introducing molten plastic material into a mold (not shown) and a manifold/deflector housing arrangement 410 for allowing

.0 communication of plastic material from a source (not shown) to the nozzle assembly 408. A manifold heater 439 is shown inserted in a manifold 438, thereby heating the manifold 438 which in turn heats the flowing plastic within a melt channel 442 and a deflector housing channel 319. The deflector housing

L5 430 is inserted in a bore 443 of the manifold 438.

As shown in FIG. 12, the nozzle assembly 408 consists of a nozzle body 412, a tip 414, a nozzle heater 416, a spring means 418, and a nozzle insulator 413. The nozzle body 412 is

10 typically made of steel, while the tip 414 may be formed from any suitable highly heat-conductive material known in the art such as beryllium/copper . The nozzle body 412 has an axial channel 420 through which molten plastic material flows. The tip 414 surrounds a terminal part of the axial channel 420. 5

If desired, the nozzle tip 414 may include a sheath 422 for thermally insulating the downstream end of the nozzle tip 414.

The sheath 422 may be formed from a resinous material which may be prefabricated. Alternatively, the sheath 422 may be 0 formed from an overflow of injected resin in the first operating cycle or cycles. The nozzle insulator 413 is installed within a cavity of the manifold plate 404 and acts to reduce the thermal communication between the nozzle body 412 and the manifold plate 404, thereby maintaining the high 5 temperature of the molten plastic material as it flows through the axial channel 420. The nozzle insulator 413 may be formed from any suitable insulating material, typically known in the art such as titanium.

0 The nozzle heater 416 may be any suitable electric heater known in the art to which current is admitted by way of a cable 424. As shown in FIG. 12, the nozzle heater 416 surrounds a portion of the nozzle body 412.

A valve stem 426 is provided to permit opening and closing of the gate 428 in the nozzle body 412. The valve stem 426 may be formed by a steel rod that extends through a passageway in the deflector housing 430 and into the nozzle body 412. The end of the valve stem 426 opposite to the gate 428 is connected to a piston head 431 by a set-screw 454.

The piston head 431 is housed within a cylinder housing which comprises the upper distal end of deflector housing 430 and formed by cylindrical wall 434. Downstroke of the piston head 431 causes the valve stem 426 to move into a position where it closes or reduces the cross sectional area of the gate 428 so as to restrict flow of the molten plastic material. Upstroke of the piston head 431 causes the valve stem 426 to move so as to increase flow of the molten plastic material through the gate 428.

The hot runner system of this preferred embodiment also includes a manifold/deflector arrangement 410 consisting of the manifold 438 and the deflector housing 430 inserted into bore 443 therein. A locating pin 429 fixes the alignment of the deflector housing 430 to the melt channel 442. The manifold 438 is formed by a distribution plate housed between the plates 402 and 404 but separated therefrom by an air gap 440. The backing plate 402 is rigidly affixed to the manifold plate 404 by a plurality of high strength bolts (not shown) which must withstand the large forces generated during the cyclic molding process.

The manifold includes the melt channel 442 forming part of the hot runner system for transporting molten plastic material from a source (not shown) to the gate 428 associated with a respective mold or molds. The manifold further includes the bore 443 into which deflector housing 430 is inserted. The manifold 438 may be formed from any suitable metal or heat conducting material known in the art. The manifold heater 439 is well known in the art and typically comprises a wire/ceramic resistive type heater with a cylindrical cross section that is seated into a groove of the manifold 438.

The deflector housing 430 surrounds and guides a portion of the valve stem 426. This is an important advantage of the present invention because this increased valve stem support reduces valve stem wear and will significantly increase the life of the valve stem. Increased valve stem life will result in reduced maintenance costs and machine downtime.

The deflector housing 430 is formed from any suitable material known in the art (usually steel) and is designed to be inserted into the manifold 438 from the top. As shown in FIG. 12, the deflector housing channel 319 mates with the melt channel 442 in the manifold 438 and the axial channel 420 in the nozzle assembly 408.

As the melt flows from melt channel 442 to flow inlet 318, it strikes the outside wall of the deflector housing 430 substantially perpendicular to valve stem 426 longitudinal axis (However, non-perpendicular flow impingement could easily be accomplished) . If channel 319 was not present, the melt would tend to flow down along the face of deflector housing 430 closest to flow inlet 318, thereby causing stagnation points behind deflector housing 430. However, in this preferred embodiment, the melt flows into channel 319 and is directed to flow around the deflector housing 430, thereby eliminating the formation of stagnation points. As the melt flows through channel 319, the depth and width of the channel decreases so as to force more and more of the melt out of the channel 319. This gradually transitions the flow to annular flow so that by the time the melt reaches the exit 317, a uniform velocity profile has been established which results in the formation of a high quality molded part.

It should be noted that even though the preceding embodiments describe a deflector body 326 (FIG. 11) that is separate from the nozzle body 324 (FIG. 11) , a single bushing could easily be fabricated that incorporates all the required features . Referring now to FIG. 13 (where like features have like numerals) , another preferred embodiment in accordance with the present invention is generally shown. In this embodiment, the deflector body 326 is a singular bushing that is inserted in the nozzle body 324 for a single-melt nozzle.

Here again, the valve stem 332 is inserted through the deflector body 326, thereby supporting and guiding the valve stem 332 while also directing the melt around the back of the valve stem. Similar to the previous embodiments, melt flows from melt channel 442 through the first melt passage 328 which is located in the upper flange of the deflector body 326. Alignment between melt channel 442 and first melt passage 328 is maintained by locating pin 334. The melt then flows through second melt passage 330 which is located inside nozzle body 324.

The melt is then directed against deflector body 326 at inlet 318 where the flow is diverted around to the back of the valve stem 332 by channel 319. The melt flow is diverted through the channel 319 and gradually spills out of channel 319 into annular area 320 such that when it reaches exit 317 of the deflector body 326, it has been transformed from circular flow to uniform annular flow which exits nozzle outlet 336 to form a high quality, molded part.

Referring now to FIGS. 14 and 15, (where like features have like numerals) another preferred embodiment of the present invention is shown comprising an injection molding nozzle tip assembly 300. In this embodiment, the principles of coat hanger maifolds previously discussed have been applied to the tip of an injection nozzle assembly. Commonly referred to as a "hot tip" or "pin point", this preferred embodiment comprises a nozzle without the valve stem as shown in the previous embodiments .

An elongated first melt passage 328 is located in a sleeve 340 for the communication of a melt to a tip 344. The sleeve 340 is rigidly affixed inside the nozzle body 324 and traps the tip 344 co-axially in the nozzle body 324. In the preferred embodiment, the sleeve is threaded into the nozzle body 324 and abuts against a top flange of tip 344. A heater 416 is wrapped around the outside of nozzle body 324 for maintaining the temperature of the melt as it flows through the nozzle assembly.

Melt flows through first melt passage 328 and is further communicated to flow inlet 318 through a tip passage 346. The flow is thus communicated to channel 319. In this arrangement, the melt flow exits nozzle outlet 336 as a uniform annular flow. Elimination of stagnation points behind the tip 344 is accomplished by forcing the melt to flow around to the back of the tip 344.

Referring to FIG. 15, a nozzle assembly similar to FIG. 14 is shown, except for the addition of a second tip passage 346 which communicates the melt flow to two sides of the tip 344. In addition, a second symmetrical channel 319 is provided. Here again, the melt flows into the channel 319 and gradually spills over into all annular flow by the time it reaches exit 317.

Referring to FIGS. 16a and 16b, another preferred embodiment in accordance with the present invention is shown. In these embodiments, the channel 319 is not formed from a groove having a curved profile but instead is a square groove profile. In FIG. 16a, the channel 319 slopes downward at a fixed angle whereas in FIG. 16b, the channel 319 has a radius which defines the path of the channel 319 along the deflector body 326.

Referring to FIG. 17, another preferred embodiment in accordance with the present invention is shown. In this embodiment, an opposing channel 319' is formed in the manifold 438 for further directing the melt flow around the deflector body 326. Channel 319 and 319' in combination form a deeper channel to direct the melt around the back of the deflector body 326. Here too, the melt gradually spills out of the channels 319 and 319' to convert the flow to uniform annular flow while eliminating stagnation points. Due to melt flow principles, this embodiment will exhibit the least amount of variations in melt properties and will produce molded parts with the least amount of variation.

Referring now to FIG. 18 (where like features have like numerals) , another preferred embodiment of the present invention is shown which comprises a deflector body 326 which has a tapered flow surface. Coat hanger manifold principles have shown that a tapered flow surface, especially in the area of the channel 319, helps to substantially reduce the pressure drop that occurs in the melt as it is diverted around a flow obstruction. The tapered deflector body 326 is inserted into a tapered receiving hole in the manifold 438, and alignment is maintained by the abutting tapered surfaces. A locating pin, similar to that shown in previous embodiments may also be used to further maintain the deflector body 326 alignment with the melt channel 442.

This tapered channel arrangement could also be utilized in the all aforementioned embodiments. These embodiments could all incorporate the use of the tapered flow surface to reduce the melt pressure drop as it flows around obstacles.

While the previous embodiments all show the use of the channel 319 on a deflector body 326 that is wrapped around a valve stem 332, the channel 319 could easily be placed directly on the outside surface of the valve stem 332. A disadvantage to this approach however is the reduction in the valve stem support provided by the deflector housing that may lead to accelerated wear of the valve stem. In addition to this drawback, it would also be necessary to incorporate an alignment feature to maintain alignment of the valve stem with the manifold channel.

Referring now to FIG. 19, another preferred embodiment in accordance with the present invention is shown wherein the channel 319 is formed integral to a bushing 431. In this embodiment, the channel 319 directs the melt to flow around the valve stem 426 rather than a deflector body. This embodiment reduces the additional valve stem support as shown in previous embodiments . It is to be understood that the invention is not limited to the illustrations described herein, which are deemed to illustrate the best modes of carrying out the invention, and which are susceptible to modification of form, size, arrangement of parts and details of operation. The invention is intended to encompass all such modifications, which are within its spirit and scope as defined by the claims.

Claims

WHAT IS CLAIMED IS:

1. In an injection molding system, a flow deflector in the stream of a flowing medium comprising: a flow inlet; a flow exit; at least one diverter between said inlet and said exit comprising; a torpedo having two substantially symmetrical inside walls; two outside walls each spaced from each said inside walls, thereby defining two substantially symmetrical funnel channels; wherein each said inside wall and each said outside wall is of substantially the same length.

2. The flow deflector of claim 1, further comprising: a valve stem; said valve stem slidably inserted into a deflector body and operatively positioned to start and stop the flow of said medium; said torpedo and said outside walls being formed on an outside surface of said deflector body.

3. The flow deflector of claim 2, wherein said deflector body is tapered.

4. The flow deflector of claim 2, wherein said torpedo and outside walls are formed on said valve stem.

5. The flow deflector of claim 2, further comprising: an elongated nozzle body having a third melt passage therein; said deflector body inserted in said third melt passage of said nozzle body; said valve stem operatively extending through said deflector body to a nozzle outlet of said nozzle housing; a first melt passage in said deflector body for the communication of said medium to a second melt passage in said nozzle body.

6. The flow deflector of claim 5, further comprising a locating pin for maintaining alignment of said flow inlet to said second melt passage and said flow inlet.

7. The flow deflector of claim 5, further comprising: an additional said first melt passage located in said deflector body for communication of said medium to an additional said second melt passage in said nozzle housing; an additional flow inlet for the communication of said medium around an additional said torpedo; an additional outside wall spaced from said additional torpedo thereby forming an additional funnel channel for the communication of said medium to said flow exit .

8. The flow deflector of claim 7 further comprising a locating pin for maintaining the alignment of said first melt passages to said second melt passages and to said flow inlets.

9. In an injection molding system, a flow deflector comprising: a heated hot runner manifold affixed between a manifold plate and a backing plate for the communication of a flowing medium to at least one nozzle assembly by at least one melt channel; at least one deflector housing inserted into said manifold, said deflector housing further comprising: a flow inlet in alignment with said melt channel for the communication of said medium to a flow exit; a torpedo and an outside wall forming at least one funnel channel located between said inlet and exit; a valve stem operatively extending through said deflector housing to a nozzle outlet of said nozzle assembly, said valve stem controlling the flow of said medium.

10. The flow deflector of claim 9, further comprising a piston head affixed to said valve stem for the movement of said valve stem to open and restrict said nozzle outlet.

11. The flow deflector of claim 10, further comprising a heater in thermal communication with said nozzle assembly.

12. The flow deflector of claim 10, further comprising a locating pin for maintaining the proper alignment of said flow channel with said flow inlet.

13. The flow deflector of claim 12, further comprising a spring means in communication with said nozzle assembly for urging said nozzle assembly against said manifold.

14. The flow deflector of claim 9, wherein said torpedo is comprised of a tear shaped protrusion affixed to an outside surface of said deflector housing.

15. The flow deflector of claim 9, wherein said outside wall is comprised of a pair of symmetrically angled walls that wrap around and down an outside surface of said deflector housing and meet at a point adjacent to said flow exit.

16. In an injection molding system, a flow deflector comprising; a nozzle bushing inserted in a cavity of a manifold plate, said nozzle bushing having a flow inlet and a nozzle outlet; a deflector body inserted in a cavity of said nozzle bushing, said deflector body being aligned with said flow inlet for the communication of a flowing medium to said nozzle outlet; a torpedo protruding from a surface of said deflector body adjacent said flow inlet, thereby urging the medium to flow around said torpedo.

17. The flow deflector of claim 16, further comprising an outside wall protruding from a surface of said deflector body, said outside wall being spaced apart from said torpedo thereby forming an expanding funnel channel for the communication of said flowing medium.

18. The flow deflector of claim 16, further comprising: an outside wall protruding from a surface of said deflector body, said outside wall being spaced apart from said torpedo thereby forming an expanding funnel channel for the communication of said flowing medium to said nozzle outlet; an elongated valve stem operatively positioned in said deflector body and running adjacent to said nozzle outlet; wherein said valve stem may be selectively positioned to control the movement of the flowing medium through said nozzle outlet.

19. The flow deflector of claim 18, wherein said valve stem is located co-axially to said nozzle body and said deflector body.

20. In an injection molding system, a flow deflector in a nozzle assembly comprising; a nozzle body having a nozzle tip disposed co-axially in a distal end of said nozzle assembly adjacent a nozzle outlet; a sleeve having a first melt passage, said sleeve disposed co-axially in said nozzle body adjacent said nozzle tip, said first melt passage in communication with said nozzle tip for the transfer of a flowing medium to said nozzle outlet; a tip passage in said nozzle tip aligned with and communicating said medium from said first melt passage to a flow inlet; a torpedo adjacent said flow inlet protruding from a surface of said nozzle tip thereby forcing the medium to flow around said torpedo; an outside wall protruding from said surface of said nozzle tip spaced apart from said torpedo thereby forming a funnel channel for directing the flow of said medium;

wherein said flowing medium exhibits substantially uniform annular flow as it exits said nozzle outlet.

21. The flow deflector of claim 20, further comprising: an additional tip passage for the communication of said medium to an additional flow inlet; an additional torpedo adjacent said additional tip passage protruding from said surface of said nozzle tip; an additional outside wall spaced from said additional torpedo and protruding from said surface of said nozzle tip, thereby forming an additional funnel channel for directing the flow of said medium; wherein said flowing medium exhibits substantially uniform annular flow as it exits said nozzle outlet.

22. In an injection molding system, a flow deflector in a nozzle assembly comprising; a nozzle body having a nozzle tip disposed co-axially in a distal end of said nozzle assembly adjacent a nozzle outlet; a sleeve having a first melt passage, said sleeve disposed co-axially in said nozzle body adjacent said nozzle tip, said first melt passage in communication with said nozzle tip for the transfer of a flowing medium to said nozzle outlet; at least one tip passage in said nozzle tip aligned with and communicating said medium from said first melt passage to at least one flow inlet; an outside wall protruding from said surface of said nozzle tip forming at least one funnel channel for directing the flow of said medium around said nozzle tip; wherein said flowing medium exhibits substantially uniform annular flow as it exits said nozzle outlet.

23. In an injection molding system, a method for transitioning a melt flow around an obstruction, comprising the steps of: providing a flow inlet; providing a flow exit; positioning at least one diverter between said inlet and said exit, said diverter comprising; providing a torpedo having two substantially symmetrical inside walls; providing two outside walls each spaced from each said inside walls, thereby defining two substantially symmetrical funnel channels; wherein each said inside wall and each said outside wall is of substantially the same length.

24. The method of claim 23, further comprising the steps of: providing a valve stem; providing a deflector body, said valve stem slidably inserted into said deflector body and operatively positioned to start and stop the flow of said medium; positioning said torpedo and said outside walls on an outside surface of said deflector body.

25. The method of claim 24, wherein said deflector body is tapered.

26. The method of claim 24, wherein said torpedo and said outside walls are formed on said valve stem.

27. The method of claim 24, further comprising the steps of: providing an elongated nozzle body having a third melt passage therein; inserting said deflector body in said third melt passage of said nozzle body; said valve stem operatively extending through said deflector body to a nozzle outlet of said nozzle housing; providing a first melt passage in said deflector body for the communication of said medium to a second melt passage in said nozzle body.

28. The method of claim 27, further comprising the steps of providing a locating pin for maintaining alignment of said flow inlet to said second melt passage and said flow inlet.

29. The method of claim 27, further comprising the steps of:

providing an additional said first melt passage located in said deflector body for communication of said medium to an additionally provided said second melt passage in said nozzle housing; providing an additional flow inlet for the communication of said medium around an additionally provided said torpedo ; providing an additional outside wall spaced from said additional torpedo thereby forming an additional funnel channel for the communication of said medium to said flow exit.

30. The method of claim 29 further comprising the steps of providing a locating pin for maintaining the alignment of said first melt passages to said second melt passages and to said flow inlets.

31. In an injection molding system, a flow deflector in the stream of a flowing melt comprising: a flow inlet; a flow exit; at least one deflector channel between said inlet and said exit, said channel decreasing in cross- sectional area and directing the flow of said melt around said flow deflector such that the melt exhibits uniform annular flow and a substantial reduction of stagnation points when said melt reaches said flow exit.

32. The flow deflector of claim 31, wherein said deflector channel reduces in cross-sectional area from said inlet to said exit such that the volumetric flow rate in said deflector channel from said inlet to said exit falls off to zero in a substantially linear fashion.

33. The flow deflector of claim 31 wherein said exit is comprised of a uniform annular cross-sectional area.

34. The flow deflector of claim 31, further comprising: a valve stem; said valve stem slidably inserted into a deflector body and operatively positioned to start and stop the flow of said medium; said deflector channel being formed on an outside surface of said deflector body.

35. The flow deflector of claim 34, wherein said deflector body is tapered.

36. The flow deflector of claim 34, wherein said deflector channel is formed on the outside surface of said valve stem.

37. The flow deflector of claim 34, further comprising: an elongated nozzle body having a third melt passage therein; said deflector body inserted in said third melt passage of said nozzle body; said valve stem operatively extending through said deflector body to a nozzle outlet of said nozzle housing; a first melt passage in said deflector body for the communication of said medium to a second melt passage in said nozzle body.

38. The flow deflector of claim 37, further comprising a locating pin for maintaining alignment of said flow inlet to said second melt passage and said flow inlet.

39. The flow deflector of claim 37, further comprising: an additional said first melt passage located in said deflector body for communication of said medium to an additional said second melt passage in said nozzle housing; an additional flow inlet for the communication of said medium through an additional said deflector channel; an additional substantially symmetrical deflector channel formed on the outside of said deflector body for the communication of said medium to said flow exit.

40. The flow deflector of claim 39 further comprising a locating pin for maintaining the alignment of said first melt passages to said second melt passages and to said flow inlets.

41. In an injection molding system, a flow deflector comprising: a heated hot runner manifold affixed between a manifold plate and a backing plate for the communication of a flowing medium to at least one nozzle assembly by at least one melt channel; at least one deflector housing inserted into said manifold, said deflector housing further comprising: a flow inlet in alignment with said melt channel for the communication of said medium to a flow exit; a deflector channel having a reducing cross-sectional area in the direction of travel of said melt, located between said inlet and exit; a valve stem operatively extending through said deflector housing to a nozzle outlet of said nozzle assembly, said valve stem controlling the flow of said melt.

42. The flow deflector of claim 41, further comprising a piston head affixed to said valve stem for the movement of said valve stem to open and close said nozzle outlet.

43. The flow deflector of claim 42, further comprising a heater in thermal communication with said nozzle assembly.

44. The flow deflector of claim 42, further comprising a locating pin for maintaining the proper alignment of said flow channel with said flow inlet.

45. The flow deflector of claim 44, further comprising a spring means in communication with said nozzle assembly for urging said nozzle assembly against said manifold.

46. In an injection molding system, a flow deflector comprising; a nozzle bushing inserted in a cavity of a manifold plate, said nozzle bushing having a flow inlet and a nozzle outlet; a deflector body inserted in a cavity of said nozzle bushing, said deflector body being aligned with said flow inlet for the communication of a flowing medium to said nozzle outlet; a deflector channel formed on a surface of said deflector body adjacent said flow inlet, thereby urging the medium to flow around said deflector body, wherein; said flowing medium exhibits a substantial reduction in stagnation points as it flows from said inlet to said exit.

47. The flow deflector of claim 46, further comprising: an elongated valve stem operatively positioned in said deflector body and running adjacent to said nozzle outlet; wherein said valve stem may be selectively positioned to control the movement of the flowing medium through said nozzle outlet.

48. The flow deflector of claim 47, wherein said valve stem is located co-axially to said nozzle body and said deflector body.

49. In an injection molding system, a flow deflector in a nozzle assembly comprising; a nozzle body having a nozzle tip disposed co-axially in a distal end of said nozzle assembly adjacent a nozzle outlet; a sleeve having a first melt passage, said sleeve disposed co-axially in said nozzle body adjacent said nozzle tip, said first melt passage in communication with said nozzle tip for the transfer of a flowing medium to said nozzle outlet; a tip passage in said nozzle tip aligned with and communicating said medium from said first melt passage to a flow inlet; a deflector channel adjacent said flow inlet formed on a surface of said nozzle tip thereby forcing the medium to flow around said nozzle tip; wherein said flowing medium exhibits substantially uniform annular flow as it exits said nozzle outlet.

50. The flow deflector of claim 49, further comprising: an additional tip passage for the communication of said medium to an additional flow inlet; an additional deflector channel adjacent said additional tip passage formed on a surface of said nozzle tip; wherein said flowing medium exhibits substantially uniform annular flow as it exits said nozzle outlet.

51. In an injection molding system, a method for transitioning a melt flow around an obstruction, comprising the steps of: providing a flow inlet; providing a flow exit; positioning at least one deflector channel between said inlet and said exit, said channel decreasing in cross-sectional area and directing the flow of said melt around said flow deflector such that the melt exhibits uniform annular flow and a substantial reduction of stagnation points when said melt reaches said flow exit.

52. The method of claim 51, further comprising the steps of: providing a valve stem; providing a deflector body, said valve stem slidably inserted into said deflector body and operatively positioned to start and stop the flow of said medium; forming said deflector channel on an outside surface of said deflector body.

53. The method of claim 52, wherein said deflector body is tapered.

54. The method of claim 52, wherein said deflector channel is formed on said valve stem.

55. The method of claim 52, further comprising the steps of: providing an elongated nozzle body having a third melt passage therein; inserting said deflector body in said third melt passage of said nozzle body; said valve stem operatively extending through said deflector body to a nozzle outlet of said nozzle housing; providing a first melt passage in said deflector body for the communication of said medium to a second melt passage in said nozzle body.

56. The method of claim 55, further comprising the steps of providing a locating pin for maintaining alignment of said flow inlet to said second melt passage and said flow inlet.

57. The method of claim 55, further comprising the steps of: providing an additional said first melt passage located in said deflector body for communication of said medium to an additionally provided said second melt passage in said nozzle housing; providing an additional flow inlet for the communication of said medium through an additionally provided said deflector channel .

58. The method of claim 57 further comprising the steps of providing a locating pin for maintaining the alignment of said first melt passages to said second melt passages and to said flow inlets.