WO2015105817A1

WO2015105817A1 - Molding material distributor

Info

Publication number: WO2015105817A1
Application number: PCT/US2015/010393
Authority: WO
Inventors: Patrice Fabien Gaillard; Edward Joseph Jenko
Original assignee: Husky Injection Molding Systems Ltd.
Priority date: 2014-01-09
Filing date: 2015-01-07
Publication date: 2015-07-16

Abstract

A molding material distributor (108) for use with an injection molding system. The molding material distributor (108) includes a molding material distributor component. The molding material distributor component includes an aluminum nitride heater (110) in thermal communication therewith.

Description

MOLDING MATERIAL DISTRIBUTOR

TECHNICAL FIELD Non-limiting embodiments disclosed herein generally relate to a molding material distributor and a molding system including a molding material distributor.

BACKGROUND

Molding is a process by virtue of which a molded article can be formed from molding material by using a molding system. Various molded articles can be formed by using the molding process, such as an injection molding process. One example of a molded article that can be formed, for example, from Polyethylene Teraphalate (PET) material is a preform that is capable of being subsequently blown into a beverage container, such as, a bottle and the like.

As an illustration, injection molding of PET material involves heating the molding material (ex. PET pellets, etc.) to a homogeneous molten state and injecting, under pressure, the so-melted PET material into a molding cavity defined, at least in part, by a female cavity piece and a male core piece mounted respectively on a cavity plate and a core plate of the mold. The cavity plate and the core plate are urged together and are held together by clamp force, the clamp force being sufficient enough to keep the cavity and the core pieces together against the pressure of the injected PET material. The molding cavity has a shape that substantially corresponds to a final cold-state shape of the molded article to be molded. The so-injected PET material is then cooled to a temperature sufficient to enable ejection of the so-formed molded article from the mold. When cooled, the molded article shrinks inside of the molding cavity and, as such, when the cavity and core plates are urged apart, the molded article tends to remain associated with the core piece. Accordingly, by urging the core plate away from the cavity plate, the molded article can be demolded, i.e. ejected off of the core piece. Ejection structures are known to assist in removing the molded articles from the core halves. Examples of the ejection structures include stripper plates, ejector pins, etc.

It is known in the art to use a hot runner for the purposes of distributing molten molding material from the plasticizer into the one or more molding cavities. Generally speaking, two types of the hot runner are known - a mechanically gated hot runner and a thermally gated hot runner. Within the mechanically gated implementation of the hot runner, a valve stem is used as means to selectively open and close the gate (and, thus, to selectively allow and stop the flow of molding material through the gate). Hence, the valve stem mechanically opens and closes the gate.

Within the mechanically gated implementations of the hot runner, the nozzle heaters and nozzle tips are used to control the thermal profile of the gate. Generally speaking, the nozzle heater and the nozzle tips are fixed components and can only affect the gate thermal profile through thermal conductivity. Therefore, it can be said that the nozzle heater and the nozzle tips can only have a limited range of optimization window for the thermal profile of the gate (that is without having to change hardware components).

It is generally known that the gate thermal profile may have an impact on the processing window of the injection molding system. Generally speaking, inability to properly control and manage the thermal profile of the gate can lead to defects, such as but not limited to: stringing, posting, crown flash, random plug blowing and the like.

SUMMARY

According to a first broad aspect of the present technology, there is provided a molding material distributor for use with an injection molding system, the molding material distributor comprising: a molding material distributor component, including an aluminum nitride heater in thermal communication with the molding material distributor component.

In some implementations, the molding material distributor component includes one of: a manifold, a sprue bushing, a nozzle body, a nozzle tip, a valve stem, and a valve stem.

According to a second broad aspect of the present technology, there is provided a nozzle for a molding material distributor, the nozzle comprising: a nozzle body and a nozzle tip attached to the nozzle body; a valve stem reciprocateable within the nozzle body and the nozzle tip; a valve stem heater encapsulated within the valve stem.

According to another broad aspect of the present technology, there is provided a nozzle for a molding material distributor, the nozzle comprising: a nozzle body positionable, in use, within the molding material distributor; an aluminum nitride heater associated with a portion of the nozzle body. According to yet another broad aspect of the present technology, there is provided a method of operating a nozzle for a molding material distributor, the nozzle including a nozzle body and a nozzle tip; a valve stem reciprocateable within the nozzle body and the nozzle tip; a valve stem heater associated with the valve stem; the method comprising at least one of: executing process window optimization, wherein the process window optimization includes at least one of: re-positioning the valve stem; varying temperature setting of the valve stem heater.

These and other aspects and features of non-limiting embodiments will now become apparent to those skilled in the art upon review of the following description of specific non-limiting embodiments in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

The non-limiting embodiments will be more fully appreciated by reference to the accompanying drawings, in which:

FIG. 1 depicts a schematic representation of an injection molding system implemented in accordance with non-limiting embodiments of the present technology.

FIG. 2 depicts a cross-sectional view of a representation of a molding material distributor according to a first non- limiting embodiment of the present technology.

FIG. 3 is a cross-section view of a representation of a molding material distributor implemented in accordance with a second non-limiting embodiment of the present technology.

The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.

DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENT(S) Reference will now be made in detail to various non-limiting embodiment(s) of a molding material distributor for use in an injection molding machine of an injection molding system. It should be understood that other non-limiting embodiment(s), modifications and equivalents will be evident to one of ordinary skill in the art in view of the non-limiting embodiment(s) disclosed herein and that these variants should be considered to be within scope of the appended claims.

Furthermore, it will be recognized by one of ordinary skill in the art that certain structural and operational details of the non-limiting embodiment(s) discussed hereafter may be modified or omitted (i.e. non-essential) altogether. In other instances, well known methods, procedures, and components have not been described in detail.

In a non-limiting embodiment, FIG. 1 shows an injection molding system 100. The injection molding system 100 includes (but is not limited to): (i) a clamp assembly 102, (ii) an injection unit 104, (iii) a mold assembly 106, and (iv) a molding material distributor 108. It is noted that the molding material distributor 108 is sometimes referred to by those skilled in the art as a "hot runner". In the illustrated embodiments, the injection molding system 100 is for manufacturing thin wall containers. However, in alternative non-limiting embodiments, the injection molding system 100 can be configured to manufacture other molded articles - preforms for subsequent blow molding into final shaped containers, medical appliances, closures and the like.

The clamp assembly 102 includes (but is not limited to): (i) a first platen 110, (ii) a second platen 112, (iii) a third platen 114, (iv) tie bars 116, and (v) a clamp 118.

The second platen 112 is configured to be movable between the first platen 110 and the third platen 114. The first platen 110 and the third platen 114 are stationary platens in a sense that they are stationary relative to each other. The second platen 112 is, therefore, movable vis-a-vis the first platen 110 and the third platen 114. Even though a three-platen assembly has been depicted here, in alternative non- limiting embodiments, the clamp assembly 102 can be implemented as a two-platen assembly, where a first platen is typically a fixed platen and a second platen is typically a movable plate.

The tie bars 116 extend between the first platen 110 and the third platen 114. The second platen 112 and the tie bars 116 are slidably connected, such that the second platen 112 is slidable relative to the tie bars 116. The third platen 114 is associated with the clamp 118. Actuation of the clamp 118 applies a clamping force to push the second platen 112 toward the first platen 110 and pull the tie bars 116 toward the third platen 114, such that the clamping force is applied across the first platen 110 and the second platen 112.

The injection unit 104 is configured to plasticize and then inject, under pressure, a molding material. In some embodiments, a separate device, known as a shooting pot, can be used for injecting the molding material. In that case, the injection unit 104 can be responsible for exclusively plasticizing the molding material.

The molding material distributor 108 is configured to receive the molding material from the injection unit 104 (or the shooting pot, where used) and to distribute the molding material to a mold cavity 120 defined by the mold assembly 106. The molding material distributor 108 is associated with the first platen 110 and molding material distributor 108. The mold assembly 106 includes a stationary mold portion 122 and a movable mold portion 124. The stationary mold portion 122 is associated with the first platen 110. The movable mold portion 124 is associated with the second platen 112.

In those embodiments where the clamp assembly 102 is implemented as a two-platen clamp assembly, it is typical to use a clamp column (not depicted) in lieu of tie bars 116. In yet alternative non-limiting embodiments of the present technology, the clamp assembly 102 can be implemented as a toggle clamp.

Movement of the second platen 112 opens and closes the mold assembly 106. The stationary mold portion 122 and the movable mold portion 124 cooperate to define the mold cavity 120. In a typical implementation, several ones of the mold cavity 120 are provided. The number of cavities within a given mold is called "cavitation" of the mold. Typical cavitation of the mold assembly 120 can be implemented as 72, 96, 126 and the like.

In operation, the second platen 112 is moved toward the first platen 110, moving the mold assembly 120 to a closed position. The clamp 118 and the tie bars 116 then apply the clamping force across the first platen 110 and the second platen 112. The clamping force squeezes the mold assembly 106 together as the injection unit 104 injects the mold cavity 120 with the molding material via the molding material distributor 108. Referring now to FIG. 2, there is depicted a cross-sectional view of a nozzle portion 200 of the molding material distributor 108 of FIG. 1. Within the embodiment depicted in FIG. 2, the molding material distributor 108 is of a mechanically gated type and, hence, the nozzle portion 200 is implemented as a valve gated nozzle (as will be described in detail herein below).

The nozzle portion 200 comprises a gate insert 202. The nozzle portion 200 further comprises a nozzle body 204 and a nozzle tip 206. Within these embodiments, the nozzle tip 206 is threadably coupled to the nozzle body 204. In alternative non-limiting embodiments of the present technology, the nozzle body 204 and the nozzle tip 206 can be implemented as a unitary structure. In yet other embodiments of the present technology, the nozzle body 204 and the nozzle tip 206 may be associated with a number of additional components or sub components.

The nozzle portion 200 further includes a valve stem 210. The valve stem 210 is configured to reciprocate up and down (as viewed in the orientation of FIG. 2). The reciprocation of the valve stem 210 opens and closes a gate 212. Reciprocation of the valve stem 210 can be implemented by various known means, such as a pneumatic actuator, hydraulic actuator, a servo motor (all of these not depicted but well known in the art). Within the illustration of FIG. 2, the valve stem 210 is shown in the valve-closed configuration. Within this configuration, the valve stem 210 is positioned within the gate 212, effectively closing the gate 212 and preventing the flow of molding material through the gate 212 (and, hence, preventing flow of molding material into the mold cavity 120 of FIG. 1). During appropriate portions of the molding cycle (such as, for example, injection phase, holding phase, etc), the valve stem 210 can be actuated into the valve-open position (not depicted). Specifically, the valve stem 210 is actuated up- wards (as viewed in the orientation of FIG. 2) and generally away from the gate 212, which causes the gate 212 to be un-obstructed by the valve stem 210, thus allowing the flow of molding material therethrough and into the mold cavity 120 of FIG. 1.

According to embodiments of the present technology, there is provided a valve stem heater 214. The valve stem heater 214 is operatively coupled by a heater wire 216 to a controller (not depicted). The controller can be a controller dedicated to the valve stem heater 214 control or the controller associated with the molding system. In some implementations of the present technology, the valve stem heater 214 is located within the valve stem 212. In those embodiments, the valve stem heater 214 can be encapsulated within the valve stem 212. Accordingly, it can be said that the valve stem heater 214 is an "internal heater", disposed within the valve stem 212. A specific technical effect of some of these embodiments of the present technology is that the valve stem heater 214 is enclosed within the valve stem 212 and, therefore, is not exposed to the harsh environment of the flow of the molding material. Therefore, in some embodiments of the present technology, the valve stem heater 214 can be a comparatively inexpensive item as it may not need to be reinforced to withstand harsh operating environments.

In some embodiments, the valve stem heater 214 is implemented as an aluminum nitride heater. An example of an aluminum nitride heater can be provided by Durex Industries, as distributed by Owen Johnson Associated Inc of Westfield, MA, United States of America. In alternative non-limiting embodiments, the valve stem heater 214 can be implemented as a ceramic heater, also available, as an example, from Durex Industries.

In those embodiments, were the valve stem heater 214 is implemented as the aluminum nitride heater, the valve stem heater 214 may include (but is not limited to): (i) an aluminum nitride body (not separately numbered), (ii) a heating element (not separately numbered) located on the aluminum nitride body, and (iii) an electrode (not separately numbered) configured to supply electrical power to the heating element. The electrode is coupled to the heater wire 216. As an example, the electrode can be electrically connected to the heater wire 216 by means of soldering. The aluminum nitride body may be made by any suitable means such as, for example, sintering.

In some embodiments of the present technology, the heating element can be implemented as a screen printed tungsten element onto the aluminum nitride body. Furthermore, in some embodiments of the present technology, the tungsten element and the aluminum nitride body can be co-fired to create a monolithic body. In a specific example of the present technology, an item to be associated with the valve stem heater 214 (such as the valve stem 210, for example) is first coated with the aluminum nitride, the tungsten element is then placed onto the aluminum nitride and the assembly is co-fired. Alternatively, the tungsten element can be first placed onto an aluminum nitride body, the assembly can be co-fired and then placed inside the item it is to be associated with (for example, inside the valve stem 210). In those embodiments, where the valve stem heater 214 is implemented as an aluminum nitride heater, the valve stem heater 214 can take many additional forms, not just the above-described internally encapsulated embodiment. For example, the valve stem heater 214 can be alternatively applied directly onto a surface of the valve stem 210. In various implementations of the present technology the valve stem heater 214 can be placed on the outer surface of the valve stem 210. Alternatively, the valve stem 210 may be at least partially hollow and the valve stem heater 214 may be placed on the inner surface of the valve stem 210. Therefore, it can be said, in a general sense, that the surface of the valve stem 210 to which the valve stem heater 214 is attached may include at least one of: (i) an inner surface the valve stem 210, and (ii) an outer surface the valve stem 210.

Additionally or alternatively, the valve stem heater 214, which can be implemented as the aluminum nitride heater, can be applied in a pattern about a circumference of valve stem 210. The specific form factor of such a pattern is not particularly limited and may depend on the specific heating needs of the specific molding material distributor 100. It is believed that those skilled in the art, having the benefit of the teachings of the present technology could easily implement such patterns for the valve stem heater 214. Therefore, it can be said that within some embodiments of the present technology, the valve stem heater 214 is applied to the valve stem 210 directly (either internally or externally). In the specific embodiments where the valve stem heater 214 is implemented as aluminum nitride heater, a specific technical effect may be categorized as provision of a heater with high power density, which makes it a very practical solution for valve stem 210 heat control - namely providing a balance between high power density and the size of the heater.

In some embodiments of the present technology, given implementations of the valve stem heater 214, it is possible to execute a method for process window optimization. In some embodiments of the present technology, the method for process window optimization comprises varying the position of the valve stem 210 having the valve stem heater 214 during the molding cycle. The exact positioning of the valve stem 210 during the process window optimization will depend on process window requirements, melt flow balance requirements, gate and/or part quality. In other embodiments of the present technology, the process window optimization can be executed by varying the temperature associated with the valve stem 210 by changing the temperature setting of the valve stem heater 214. In yet additional non-limiting embodiments of the present technology, the process window optimization can be implemented by varying both the position of the valve stem 210 and the temperature of the valve stem heater 214.

In some embodiments of the present technology, the process window optimization can be applied simultaneously to all nozzle portions 200 of the molding material distributor 100. In alternative embodiments of the present technology, the process window optimization can be applied on individual basis to one or a subset of the nozzle portions 200 of the molding material distributor 100. Therefore, in some embodiments of the present technology, the process window optimization can be tailored to the specific needs of a given one of the nozzle portions 200 within the molding material distributor 100. Hence it can be said that embodiments of the present technology provide for the process window optimization, which in turn provides the ability to have a very precise "on the fly" optimization without requiring any hardware change to affect the change in process window.

It should be noted that even though within the illustration of FIG. 2, the gate portion 200 is illustrated as mechanically gated, alternative embodiments of the present technology can be equally applied to thermally gated nozzles.

An example of this alternative non- limiting embodiment is depicted in FIG. 3, which depicts a cross section of a nozzle portion 300 of the molding material distributor 108 of FIG. 1, the nozzle portion 300 being implemented in accordance with additional non-limiting embodiments of the present technology. Within the embodiment depicted in FIG. 3, the molding material distributor 108 is of a thermally gated type and, hence, the nozzle portion 300 is implemented as a thermally gated nozzle (as will be described in detail herein below). In the illustrated embodiment, the nozzle portion 300 comprises a nozzle body 301. The nozzle body 301 generally includes a nozzle housing 302. Coupled to the nozzle housing 302 is a nozzle tip 304. In some embodiments, the nozzle tip 304 is coupled to the nozzle housing 302 by means of a tip retainer 306. In some implementations, the nozzle housing 302, the nozzle retainer 306 and the nozzle tip 304 are threadably coupled to each other.

In these embodiments, the nozzle portion 300 can be said to be of a three piece configuration - i.e. the nozzle housing 302, the nozzle tip 304 and the nozzle retainer 306. In alternative non-limiting embodiments, the nozzle portion 300 can be of a two-piece configuration, the nozzle tip 304 can be directly coupled to the nozzle housing 302. Alternatively, the nozzle tip 304 and nozzle housing 302 can be constructed of multiple sub-components. There is also provided, in accordance with embodiments of the present technology, a nozzle tip heater 308, the nozzle tip heater 308 being implemented as an aluminum nitride heater. The nozzle tip heater 308 is operatively coupled to a heater wire 310. Within these embodiments, it is also possible to implement the process window optimization, as has been described above. Within the specific implementation of the nozzle portion 300 or any other possible thermally gated implementation of the molding material distributor 108, execution of the process window optimization can lead to elimination of the need for high conductivity material to be used for the nozzle tip 304, thus potentially reducing the size of the nozzle tip 304. Generally speaking, in those embodiments of the present technology where the valve stem heater 214 is implemented as an aluminum nitride heater, it can be applied to other hot runner nozzle components and, therefore, can be referred to as a hot runner component aluminum nitride heater. Within those embodiments, the hot runner component aluminum nitride heater can be applied to one or more of: (i) the valve stem 210, as has been described above, (ii) the nozzle tip 206, and (iii) the nozzle body 204.

Additionally or alternatively, the hot runner component aluminum heater can be applied to (i) a manifold (not depicted) of the molding material distributor 108, (ii) a sprue bushing (not depicted) of the molding material distributor 108, as well as other components of the molding material distributor 108. The same variations of the process window optimization control can be applied, as has been described above. Even though the above description has been presented using the injection molding system 100, it should be understood that embodiments of the present technology can be implemented in other types of molding systems, such as compression molding systems, transfer molding systems, injection- compression molding systems and the like. By the same token and generally speaking, it can be said that embodiments of the present technology can be implemented within any systems that uses molten material (resin, plastic or otherwise) to produce final or semi-final (i.e. intermediary) articles.

The description of the embodiments of the present technology provides only examples of the present technology, and these examples do not limit the scope of the present technology. It is to be expressly understood that the scope of the present technology is limited by the claims only. The concepts described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present technology. Having thus described the embodiments of the present technology, it will be apparent that modifications and enhancements are possible without departing from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims:

Claims

WHAT IS CLAIMED IS:

A molding material distributor (108) for use with an injection molding system, the molding material distributor (108) comprising:

a molding material distributor component, including:

an aluminum nitride heater (214, 308) in thermal communication with the molding material distributor component.

The molding material distributor (108) of claim 1, wherein:

the aluminum nitride heater (214, 308) includes an aluminum nitride body, a heating element located on the aluminum nitride body, and an electrode configured to supply electrical power to the heating element.

The molding material distributor (108) of claim 1, wherein:

the aluminum nitride heater (214, 308) is applied directly onto a surface of the molding material distributor component.

The molding material distributor (108) of claim 3, wherein:

the surface of the molding material distributor component includes at least one of: an inner surface the molding material distributor component, and an outer surface the molding material distributor component.

The molding material distributor (108) of any of the claims 1 - 4, wherein:

the aluminum nitride heater (214, 308) is applied in a pattern about a circumference of the molding material distributor component.

The molding material distributor (108) of any of the claims claim 1 - 5, wherein:

the molding material distributor component includes one of:

a manifold,

a sprue bushing,

a nozzle body (204, 302),

a nozzle tip (304),

a valve stem (210), and a valve stem (210).

7. The molding material distributor (108) of claim 1, wherein:

the molding material distributor component includes a valve stem (210), the valve stem (210) defining an internal recess, and the aluminum nitride heater (110) being located in the internal recess.

8. A nozzle (200) for a molding material distributor (108), the nozzle (200) comprising:

a nozzle body (204) and a nozzle tip (206) attached to the nozzle body (204); a valve stem (210) reciprocal within the nozzle body (204) and the nozzle tip (206);

a valve stem heater (214) encapsulated within the valve stem (210).

9. The nozzle (200) of claim 8, wherein the nozzle body (204) and the nozzle tip (206) are threadably connected to one another.

10. The nozzle (200) of claim 8, wherein the nozzle body (204) and the nozzle tip (206) are integrally formed.

11. The nozzle (200) of any one of claims 8-10, wherein the valve stem heater (214) is implemented as an aluminum nitride heater.

12. A nozzle (200, 300) for a molding material distributor (108), the nozzle (200, 300) comprising:

a nozzle body (204, 301) positionable, in use, within the molding material distributor (108);

an aluminum nitride heater (214) associated with a portion of the nozzle body (204, 301).

13. The nozzle (200) of claim 12, wherein the nozzle (200) is implemented as a mechanically gated nozzle (200) that includes a valve stem (210) and wherein the aluminum nitride heater (214) is coupled to the valve stem (210).

14. The nozzle (300) of claim 12, wherein the nozzle (300) is implemented as a thermally gated nozzle (300) and wherein the aluminum nitride heater (214) is positionable within a melt flow path within the thermally gated nozzle (300). 15. A method of operating a nozzle (200) for a molding material distributor (108), the nozzle (200) including a nozzle body (204) and a nozzle tip (206); a valve stem (210) reciprocal within the nozzle body (204) and the nozzle tip (206); a valve stem heater (214) associated with the valve stem (204); the method comprising:

executing process window optimization, wherein the process window optimization includes at least one of:

- re-positioning the valve stem (210); and

- varying temperature setting of the valve stem heater (214).

16. The method of claim 15, wherein the nozzle (200) is one of a plurality of nozzles (200) used within the molding material distributor (108), and wherein said process window optimization is executed for all of the plurality of nozzles (200).

17. The method of claim 15, wherein the nozzle (200) is one of a plurality of nozzles (200) used within the molding material distributor (108), and wherein said process window optimization is executed exclusively for the nozzle (200).

18. The method of claim 15, wherein the nozzle (200) is one of a plurality of nozzles (200) used within the molding material distributor (108), and wherein said process window optimization for the nozzle (200) is executed differently from process window optimization for another one of the plurality of nozzles (200).

19. The method of claim 18, wherein said process window optimization for the nozzle (200) and the process window optimization for the other one of the plurality of nozzles (200) is done based on the thermal profile needs of the respective ones of the nozzle (200) and the other one of the plurality of nozzles (200).