CA2450923A1 - Multiple gating nozzle - Google Patents
Multiple gating nozzle Download PDFInfo
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- CA2450923A1 CA2450923A1 CA002450923A CA2450923A CA2450923A1 CA 2450923 A1 CA2450923 A1 CA 2450923A1 CA 002450923 A CA002450923 A CA 002450923A CA 2450923 A CA2450923 A CA 2450923A CA 2450923 A1 CA2450923 A1 CA 2450923A1
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Abstract
A method and apparatus for runnerless injection molding of plastic materials utilizing a novel valve stem for controlling the opening and closing of at least two gates in a single injection nozzle. The method and apparatus includes at least two separate melt streams whose flows are not obstructed by the valve stem. These melt streams may contain the same plastic material or different plastic materials and the injection nozzle may be either simultaneously or sequentially activated for filling the mold cavity.
Description
~L'rI_~LE GATING 1~LOZZLE
Field of The Inventloa The t invention relates to a method and apparatus for runnerless injection molding, provided with a novel valve gate for permitting at least two gates to be controlled in a single nozrle. .In particular, the invention relates to an improved method and apparad~s for molding hollow articles and prefomas for blow molding which have a layered wall .
Bsd~round of the Invention This invention concerns injection molding nozzles used to iqjoct plastic material into the cavity of a mold. Such noales receive molten plastic maurial from an injection molding machine and diroct the same into a mold cavity through a passage called a gate.
Two methods exist for this transfer: thermal, or open, gating; and valve gating.
In thermal gating, the gate is an open aperture through which plastic can pass doting injection of plastic material. The gatt is rapidly cooled at the end of the injection cycle to '" the plastic material which remains in the gate to act as a plug to prevent drool of plastic material into the mold cavity when the mold is open for ejection of parts.
In the next injection cycle, tln; cooling to tlar gate is rarwved and hot plastic material pushes the plug into the mold cavity, where it melts and mixes with the new melt stream.
In valve gating, gate opening and closing is independent of injection pressure and/or cooling, and is achieved mechanically, with a pin that travels back and forth, to open and close die gate.
Generally, valve gating is preferable to thermal gating because the gate mark left by valve gating on the finished molded part after injection is complete is much smaller than that which results from thermal gating. Larger gate sizes can also be used in valve gate systems, leading to fasts filling of the mold cavities and therefore shorter molding cycle times.
However, some disadvantages are frequently associated with valve gates. These disadvantages include "weld lines", which are areas where multiple melt flow fronts meet, and valve stem wear. Weld lines tend to introduce was or Ions of mechanical strength into the finished part and result from tln; fact that the valve stem is surrounded by the plastic material, splitting the melt st-oam, which is later rejoined at the end of the stem, and this re-combining of the stream leads to weld lines. Hence, there exists a need for a gate design which allows for the melt stream, or streams in the case of two or more plastic materials, to remain separate while still being contmUod with a common valve stem.
The valve stem is also subject to wear from mechanical stress, due to stem deflection from the incoming pressurized melt, and thermal stress, from constant contact with the melt. This wear is exacerbated in cases where reinforced plastic materials, i.e., those containing glass or other fibers or materials, are injected. H~ce, there exists a need for a gate design which mitigates the wear of the valve stem.
The injection of two or more separate melt streams into a mold cavity, whether simultaneously or sequentially, is referred to as co-injection, and leads to layered wail structures in hollow articles and blow molding preforms. The prior art includes a multitude of processes and apparatuses for forming molded articles from multiple plastic materials by co-injection. For e~cample, U.S. Pat. Nos. 5,028,226 and 4,717,324 show simultaneous and sequential co-injection apparatuses and methods, respectively. Both patents show one nozzle dedicated to each mold cavity wherein the cavity is filled by injecting two or more resins through a single gate.
Field of The Inventloa The t invention relates to a method and apparatus for runnerless injection molding, provided with a novel valve gate for permitting at least two gates to be controlled in a single nozrle. .In particular, the invention relates to an improved method and apparad~s for molding hollow articles and prefomas for blow molding which have a layered wall .
Bsd~round of the Invention This invention concerns injection molding nozzles used to iqjoct plastic material into the cavity of a mold. Such noales receive molten plastic maurial from an injection molding machine and diroct the same into a mold cavity through a passage called a gate.
Two methods exist for this transfer: thermal, or open, gating; and valve gating.
In thermal gating, the gate is an open aperture through which plastic can pass doting injection of plastic material. The gatt is rapidly cooled at the end of the injection cycle to '" the plastic material which remains in the gate to act as a plug to prevent drool of plastic material into the mold cavity when the mold is open for ejection of parts.
In the next injection cycle, tln; cooling to tlar gate is rarwved and hot plastic material pushes the plug into the mold cavity, where it melts and mixes with the new melt stream.
In valve gating, gate opening and closing is independent of injection pressure and/or cooling, and is achieved mechanically, with a pin that travels back and forth, to open and close die gate.
Generally, valve gating is preferable to thermal gating because the gate mark left by valve gating on the finished molded part after injection is complete is much smaller than that which results from thermal gating. Larger gate sizes can also be used in valve gate systems, leading to fasts filling of the mold cavities and therefore shorter molding cycle times.
However, some disadvantages are frequently associated with valve gates. These disadvantages include "weld lines", which are areas where multiple melt flow fronts meet, and valve stem wear. Weld lines tend to introduce was or Ions of mechanical strength into the finished part and result from tln; fact that the valve stem is surrounded by the plastic material, splitting the melt st-oam, which is later rejoined at the end of the stem, and this re-combining of the stream leads to weld lines. Hence, there exists a need for a gate design which allows for the melt stream, or streams in the case of two or more plastic materials, to remain separate while still being contmUod with a common valve stem.
The valve stem is also subject to wear from mechanical stress, due to stem deflection from the incoming pressurized melt, and thermal stress, from constant contact with the melt. This wear is exacerbated in cases where reinforced plastic materials, i.e., those containing glass or other fibers or materials, are injected. H~ce, there exists a need for a gate design which mitigates the wear of the valve stem.
The injection of two or more separate melt streams into a mold cavity, whether simultaneously or sequentially, is referred to as co-injection, and leads to layered wail structures in hollow articles and blow molding preforms. The prior art includes a multitude of processes and apparatuses for forming molded articles from multiple plastic materials by co-injection. For e~cample, U.S. Pat. Nos. 5,028,226 and 4,717,324 show simultaneous and sequential co-injection apparatuses and methods, respectively. Both patents show one nozzle dedicated to each mold cavity wherein the cavity is filled by injecting two or more resins through a single gate.
In the systems shown in each patent, a valve stem is used to pnwent resin flow through the gate after injection is complete. In these systems, the hot runner systems employed to receive the various resins from their source for conveyance to the mold cavities are very complicated:. Consequently, such hot runner systems lead to mold designs which are not compact and thereby allow fewer cavities and fewer articles to be molded within a given space on a molding machine.
U.K. Patent No. 1,369,744 discloses a sequential co-injection system using separate channels, commonly referred to as spree channels, for each melt stzeam, and sliding shuttles which fiu~ction as valve stems to open and close the connection between the injection machine and the channels. However, these separate melt channels converge into a single common gate area prior to injection, so that some potential for contamination betv~roen streams exists. Furtlamnore, the shuttles are hydraulically actuated, increasing the complexity of the nozzle and allowing the risk of leaking hydraulic fluid to contaminate the streams.
U.S. Patent No. 4,470,936 also discloses a sequential co-injection system using separate spree channels for each melt shram, with each spree channel being independently heated and converging to a common gate. In this system, a shuttle ball or swing gate switches the flow of material from one spree channel to the other.
This system also sui~ers from the potential for contamination between streams, such as described above for U.K. Patent 1,369,744. This is a sp~ial concern as wear of the shuttle ball or swing gate is likely in normal use.
ZS
U.S. Patent No. 5,651,99$, assigned to the assignee of the present invention, discloses a method and apparatus for either sequential or simultaneous co-injection utilizing two opposing injection nozzles on the core and cavity sides respectively of the mold. Although effective, this arrangement requires an additional injection nozzle which must also receive resin from an injection unit on the opposite (movable) mold core half.
This arrangement significantly increases the space requirements for the mold and may not be acceptable in some applications.
U.S. Patent No. 5,125,816 is similar to U.S. Patent No. 5,651,998 in that sequential co-injection is achieved by opposing gates on both the mold core and cavity respectively. However, in this arrangement the moveable mold half is fitted with slide cores containing tubular passages for feeding resin to one half of the molded part. These slide. cores move via hydraulic cylinders to define secondary mold cavities, which arc in turn filled by gates on the opposing mold half. This system suffers from disadvantages due to its complexity, the additional mold hardware requirements, including the aforementioned slide cores and additional injection nozzles; and the need for special manufacturing attention due to tight tolerances.
U.S. Patent No. 3,873,656 shows a co-injection apparatus wherein at least two plastics are injected into a mold cavity through different gates, using a valve gating system. This design is only suitable for molding very large plastic articles.
Also, the hot runner system taught does not have the capability for allowing separate temperature control of the different resin types, which inherently limits the variety of resins that can be used together in one system. Furthermore, since the gates are far apart from one another, the flow of each resin will not be synunetrical throughout the part, but instead will be biased in the area of the gate.
U. S. Patent No. 4,289,191 shows injection molding of molten wax into a precision metal die, wherein hollow parts are molded to extremely tight tolerances of 10.012 mm. The wax stream flows from a nozzle having a central bore to a cavity or space formed between the nozzle tip, which has a relief channel, and the socket on the -S-exterior of the die, and then into two or more separate spore ports that feed into the mold cavity. Control of wax flow is accomplished by a retractable plunger in the nozzle which functions like a conventional valve stern. Although more than one spree port is employed to supply material to the mold, tlurse- ports are downstream the valve in the nozzle. Also, the valve stem obstructs the melt flow by being in the center of the melt stream, leading to weld lines. Finally, no provision is made for two or more separate resins to be injected through the two or more spree ports, so this method cannot be used for co-injection Pm'Po~s.
U.S. Patent No. 5,645,874 shows a multiple gate nozzle in which each nozzle associated with a respective gate is equipped with an individual heater to allow independent thermal gating. In this arrangement, a central flow passage feels a plurality of radially extending branch passages leading to each respective gate, and as such, cannot accommodate multiple sources of resin or even sequential melt flow, and therefore cannot be used for co-injection purposes.
U.S. Patent No. 4,702,686 shows a nozzle vvhercin a tapered plate divides a central flow channel into two partial channels prior to the nozzle tip and gate. This nozzle cannot accommodate the separate, different, resin sources require for coinjection purposes.
Summary of The Invention It is an object of the present invention to provide an novel apparatus and method for injecting at least two plastic materials into a mold cavity which obviates or mitigates at least one of the disadvantages of the prior art.
According to a first aspect of the present invention, tta~re is provided a method of co-injecting at least two different plastic materials to form a mufti-layer molded product -b using a hot runner injection molding machine with a separate channel for each material, each channel having an end in communication with a separate gate for feeding an injection mold, the method comprising:
(f) heating the plastic materials in their separate channels or storage areas;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gate into the injection mold and preventing further flow of material from the first channel;
(iii) injecting a selected amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
(iv) injecting a selected amount of a third material, said third material being selectod from one of said first plastic material and any other plastic material, said third material being injectod from its respective channel via its respective gate, said respective gate being separated from said second gate by a gate separating means; and (v) moving a valve stem forward to close each said gate.
According to another aspect of the present invention, there is provided a method of co-injecting at least two different plastic materials to form an article having abutting portions of said different plastic materials using a hot runner injection molding machine with a separate channel for each different plastic material, each channel having an end in communication with a respective separate gate for feeding an injection mold, comprising the steps of (f) heating each different plastic material in its respective separate channel;
(ii) injecting a metered amount of a first plastic material from a first channel through a first gate into the injection mold and simultaneously injecting a metered amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
-'-(iii) injecting a metered amount of a plastic material into the injection mold from its respective individual channel through its respective gate; and (iv) moving a valve stem to block all gates leading into the injection mold.
According to another aspect of the present invention, there is provided a method of co-injecting at least two different plastic materials to form a mufti-layer molded product employing a hot runner injection molding machine with a ssparate channel for each material, each channel having an exit in communication with a eve separate gate for feeding an injection mold, the method comprising the steps of (f) heating the plastic materials in their separate channels;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gatc into the injection mold and inhibiting further flow of material from said;
(iii) injecting a selected auiount of a second material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means comprising a protrusion that engages a valve stem to support said valve stem;
(iv) injecting a selected amount of a third material, said third matexial comprising at least one of said first material and another material, said third material being injected from its respective channel and its respective gate into said injection mold;
and (v) moving said valve stem to close at least one of said gates, each gate which is not closed by said valve stem being gated by thermal shut-off to inhibit the flow of plastic into the mold.
According to yet another aspect of the present invention, there is provided a hot runner injection molding apparatus for co-injecting at least two plastic materials into a forming mold, comprising:
a separate channel for each of said at least two plastic materials;
-g-a separate heating means for each of said separate channels;
a separate gate for each of said at least two plastic materials, each said gate being in communication with a corresponding one of said separate channels;
a valve stem movable between a first position wherein each said separate gate is open and a second position wherein each said separate gate is closed; and a gate separating means comprising a protrusion separating each said separate gate from each other said separate gate, said protrusion co-operating with said valve stem to inhibit deflection thereof.
According to yet another aspect of the prat invention, there is providod a hot runner injection molding apparahis for co-injecting at least two different plastic materials through separate channels to farm a mufti-layer moldod product, each separate channel being independently heated and having an end in communication with a respective separate gate entrance into a forming mold, a gate separating means to prevent intermixing of the different plastic materials prior to exit at the gates, and a valve stem capable of longitudinal movement to permit and inhibit the flow of the different plastic materials through said gates, said gate separating means engaging a portion of said valve stem to inhibit lateral deflection thereof.
The present invention provides a nozzle for plastic injection molding machines whereby flow disturbances and the resulting weld lines, which normally occur with known valve gate systems, are reduced. Further, the present invention provides an injection system and method that employs relatively simple nozzle and hot runner designs. The present invention also provides a space-efficient, mufti-material injection 2S system for efficiently molding a plurality of articles in a mufti-cavity mold. The present invention also provides an injection system and method wherein gates of different sizes can be accommodated in a single injection nozzle, each gate size being self according to the viscosity of the particular plastic material flowing through it.
_g_ The present invention provides a novel method for runnerless injection molding, provided with a valve gate assembly, including at least two melt stmams separated at the edge of the mold cavity by a gate separating means, a valve stem that is reciprocally movable and at least two gates that are opened and closed by the valve stem.
Brief Description of T6e Dnwiog~
The p~tsent invention will now be describe, by way of example only, with reference to the attached Figures, wl~in:
Figure 1 is a sectional view of a hot n~nneer-nozzle assembly for a mold cavity wherein two separate plastic materials fed to the nozzle tip and controlled by a single valve stem;
Figure 2 is an expanded view of the nozzle assembly of Figure 1;
Figure 3 is a set of sectional views of a molded article detailing the layesod wall structure after first, second, and third shots of plastic material;
Figure 4a is an end view of a nozzle assembly with three gates in accordance with the present invention;
Figure 4b is a section of the nozzle assembly of Figure 4a, taken along line A-A
of Figure 4a;
Figure 4c is a section of the nozzle assembly of Figure 4a, taken along line B-B of Figure 4a;
Figure Sa is a side view of a valve stem for the nozzle assembly of Figure 4a;
and Figure Sb is an end view of the valve stem of Figure Sa.
Description Of the Preferred Embodiments In Figure 1 an embodiment of a valve gate assembly and injection nozzle in accordance with the present invention is indicated generally at 20 which is, in this embodiment of the present invention, a co-injection hot nuuxt system which accommodates two plastic materials. One plastic material is provided from a source comprising extruder 24 and the other plastic material is provic~d from a separate extr~a~
(not shown). As used herein, different plastic materials is not intended to be limited to different material compositions, such as PET versus EVOH, but can also comprise, without limitation, materials with generally the same composition but different characteristics, such as PET in different colours or virgin PET versus recycled PET, foamed plastic materials versus non-foamed plastics, etc.
In this example, the portion of the hot nmner system connected to extruder 24 is maintained at a temperatiure rrangir ; from 500° to 550°F, the optimum processing temperatim for a thermoplastic resin such as polyethylene teraphth,alate, or PET, by suitable heaters in weU-known fashioa. Conversely, the portion of the system, illustrated in broken lines, which is connected to the second extn~der is maintained at a different temperature, such as the range from 400° to 440°F, the optimum processing tearperature for a thermoplastic resin such as EVOH. It is to be noted that the plastic materials selected and their optimum processing temperatures are merely examples of the present invention and their use in the present description is not intended as a limitation of the present invention.
A c~tral manifold block 51 maintaira~d at an operating temperature ranging from 500 to 550°F by heating elements 52 and receives plasticized resin from extender 24 through channels 53 and 54. A spool, or rotary, valve 56 is in circuit with channel 54 and operated by link mechanism 57, and controls the charging of reservoir 58 of the shooting pot, or injection cylinder, 59 equipped with an injection piston or charging piston 61.
Valve 56 is formed with a transverse throughbore 62 and is shown in the close position in Figure 1.
With reference now to Figures 1 and 2, reservoir 58 communicates with a nozzle assembly 64 via channel 63. Htating elements 52 maintain the desired processing temperature of channel 63 as the PET or other plastic material progresses through to channel 90 of nozzle assembly 64 to a gate 76a. As shown, gate 76a is separated from an adjacent gate 76b by a gate separating means. In a preferred aspect of the present invention, the gate separating means is in the form of a protrusion 86 that partially overlaps. central valve stem 83, which is shown in the retracted position in these Figures.
This partial overlap of valve stem 83 and protrusion inhibits any lateral aligannent problams that might ordinarily occur where the stem moves longitudinally backwards and forwards over millions of injection cycles under very high injection pressures exceeding twenty thousand psi. While the overlap between protrusion 86 and steer 83 is preferred, it is not essential to the invention and, as wilt be understood by thox of skill in the art, the gate separating means neod not be a protrusion and can instead be any .suitable barrier between the gates 76.
1S As best seen in Figure 1, a manifold segment 65 is secured to manifold block 51 and is heated by elements 66 to maintain optimum temperature (400° to 440°F) in the hot runner connecting the second extruder (not shown) to channel 67 and to a reservoir 68 of a second shooting pot 69 which is equippod with an injection err charging piston 71. Here again, a spool or rotary valve 72 (shown in the closed position relative to channel 67 in Figure 1 ) controls charging of reservoir 68. In the closed position of the spool valve 72, reservoir 68 communicates with nozzle assembly 64 via a channel 70 through a cut-out ?5. When the spool valve 72 is open, channel 70 is closed and a link mechanism operates to rotate valve 72.
ZS As shown in Figure 2, nozzle assembly 64 includes a central spigot 73 in thermal contact with manifold block 51 immediately adjacent local beating elements 52.
and spigot 73 is preferably fabricated from a good nxtallic thermal conductor such as beryllium copper. Spigot 73 is supported by minimal bearing surfaxs ?7,78, best seen in ~ 12-Figure 2, in a housing 79 and is spacod, from spigot 73 along substantially its entire length to form an insulating air gap 8I. Air gap 81 inhibits conduction of heat from the spigot 73 to the housing 79 to maintain the desirod process temperature, controlled by heating means 82, as the plastic material, such as EVOH, progresses through channel 80 of housing 79 to gate 76b.
The size of each of gates 7Ga and 7bb can be selected as desired, largely independent of the other of gates 76a and 76b, which is advantageous in situations where the viscosities of the different resin streams are significantly different or wherein a significantly larger amount of one material than the otls~ is to be injected in an injection cycle.
Thus, it is apparent that the nozzle and valve gate and the hot rcan~ system of the present invention is effective to maintain different optimum process temperatures appropriate to two diffcrcnt plastic materials from the source of the plastic materials to the nozzle gates.
As will be apparent to those of skill in the art, because the plastic material is supplied to gates 76a and 7fib via channels 80 and 90, respectively, the plastic. materials do not contact the majority of stem 83 and thus wear of stem 83 is reduced in comparison to conventional designs.
A preferred method of operation will now be described with reference to the PET
and EVOH example described above. To prime the hot runner system initially, extruder 24 and the second extruder, including their respective co-operating shooting pots 59 and 69 are purged and the extruders are moved into operative position relative to their respective manifolds. With valve stem 83 and spool , valves 56 and 72 in the open position, shooting pot reservoirs 58 and 68 are charged with PET and EYOH
material, respectively. Next, valve stem 83 is closed by a piston 84 and purged resin in the mold cavity is removed.
Thcreafler the mold is closed and clamped, valve stem 83 is opened and the following sequence is perform. First, spool valve 56 is closed and injection piston 61 is advanced until it bottoms at the point indicated by the reference numeral 100, discharging a measured amount of PET into the mold cavity through channel 63 and gate 76a, which is separated from the adjacent gate 76b by a protrusion $G. This constitutes the first shot of PET into the mold cavity, as shown schematically at F in Figure 3.
I0 . .
Piston 61 is held forward (in i~ bottomed position 100) blocking to reservoir 58 to prevent backflow of PET compound from channel 63 into reservoir 58.
That is, the piston 61 is held bottomed to block access to reservoir S8 because upon subsequent operation of piston 7I to inject EVOH, the EVOH injection pressure would have a tendency to displace PET from channel 63 back into reservoir 58.
Next, spool valve 72 is closed to the second extruder and opened to channel 70.
Injection piston 71 is moved until it bottoms at IOI and thus discharges a measured amount of EVOH into the cavity through channel 70 and gate 76b. This constitutes the first shot of EVOH into the mold cavity (second shot of resin) to develop the three-layer wall as shown schematically at S in Figure 3. As will be apparent, flee volume of the first and second shots of resin is less than the total volume of the mold cavity.
Next channel 70 is closed by appropriate rotation of spool valve 72 and spool valve 56 is opened, allowing extruder 24 to complete the filling of the mold cavity with PET and to pack the molded part while piston 61 remains bottomed, blocking access to reservoir 58. This step constitutes the second shot of PET (third shot of resin) to develop a five-layer wall, as shown schematically at T in Figure 3. Thus, a five-layer wall structure is molded using two resins.
After packing is completed, valve stem 83 is moved forward to the closed position, where it blocks both gates 76a and 76b and piston 61 is now freed to move.
Extruder 24 is operated to recharge reservoir 58 of shooting pot 59, displacing piston 61 until it contacts an injection stop Sa, shown in Figure 1. The positioning of stop Sa controls and measures the amount of PET introduced i~o the reservoir 58.
In similar fashion, the injection stop Sb controls and measures the amount of EVOH introduced into the reservoir 68. During the course of packing the mold cavity, the reservoir 68 is recharged by opening spool valve 72 to allow the second cxt:vder to displace piston 71 until the piston contacts its injection stop Sb, thus charging reservoir 68 with a measured amount of EVOH compound. After a suitable cooling interval, the I S mold is opened and the article is ejby known means. The above cycle is can then be repeated, in continuous, automatic fashion, to generate additional layered articles.
It is also contemplated that articles comprising two or morn layers of materials can be manufactured with the present invention, wherein one of the layers comprises a foamed material. For example, a first plastic material, such as a co-polymer of ethylene and vinyl acetate, can be injected into the mold to form the outer layer of the final article and a second plastic material, such as polyproylene, is then injected to fornn a foamed core. Another layer of the first plastic material can then be injected to seal the foam material between the layers of the first material, much like a sandwich. It is also contemplated that the simultaneous injection of two or more different materials can also be performed with the present invention. This allows, for example, the manufacture of articles of PET-PEN resin blends.
-IS-As will be apparent to those of skill in the art, the present invention need not be limited to nozzle and valve gate assemblies with only two gates and can instead include three or more gates, if desired. In another embodiment of the present invention, shown in Figures 4a, 4b and 4c, a nozzle assembly is shown wherein three ~parate gates food tht~ee different plastic materials into one mold cavity. In this embodiment, the gates 200, 204 and 208, shown in Figure 4a, can be different sizes or the same size (not shown) and each gate is separated from the other two by a protrusion 212, best seen in Figures 4b and 4c.
Figure 4a shows the pie-shaped arrangement of the three nozzle portions 216, and 224 with insulating plates 228a, 228b and 228c, made of a suitable material as will occur to those of skill in the art. Plates 228 separate each nozzle portion 216, 200 ail 224 to maintain different thermal profiles for each plastic material type being carried to each gate 200, 204 and 208, as dictated by the properties of particular materials.
Figures Sa and Sb show a valve stem 240 for the nozzle assembly of Figures 4a, 4b and 4c and the slot 244 which engages protrusion 212, slot 244 being defined between pins 248, 252 and 256 which close respective ones of gates 200, 204 and 208 when stem 240 is advanced toward protrusion 212. While the discussion above has only described a single stem in the nozzle assembly, it is contemplated that in some circumstances more than one valve stem can be employed in the assembly, each valve stem being individually actuated and gating one or more gates.
It is contemplated that in some circumstances both valve gating and thermal can gating can be employed in a single nozzle assembly in accord~e with the present invention. For example, as illustrated in Figure 4a wherein gate 204 is much smaller than gates 200 and 208, one or more gates can be much smaller, relative to the other gates, in the nozzle assembly and these smaller gates can be thermal gated in a conventional manner while larger gates, such as gates 200 and 208, can be valve gated.
It will be understood, of course, that modifications can be made to the embodimcnts of the invention illustrated and described herein without departing from the scope and purview of the invention as defined by the aclaims.
U.K. Patent No. 1,369,744 discloses a sequential co-injection system using separate channels, commonly referred to as spree channels, for each melt stzeam, and sliding shuttles which fiu~ction as valve stems to open and close the connection between the injection machine and the channels. However, these separate melt channels converge into a single common gate area prior to injection, so that some potential for contamination betv~roen streams exists. Furtlamnore, the shuttles are hydraulically actuated, increasing the complexity of the nozzle and allowing the risk of leaking hydraulic fluid to contaminate the streams.
U.S. Patent No. 4,470,936 also discloses a sequential co-injection system using separate spree channels for each melt shram, with each spree channel being independently heated and converging to a common gate. In this system, a shuttle ball or swing gate switches the flow of material from one spree channel to the other.
This system also sui~ers from the potential for contamination between streams, such as described above for U.K. Patent 1,369,744. This is a sp~ial concern as wear of the shuttle ball or swing gate is likely in normal use.
ZS
U.S. Patent No. 5,651,99$, assigned to the assignee of the present invention, discloses a method and apparatus for either sequential or simultaneous co-injection utilizing two opposing injection nozzles on the core and cavity sides respectively of the mold. Although effective, this arrangement requires an additional injection nozzle which must also receive resin from an injection unit on the opposite (movable) mold core half.
This arrangement significantly increases the space requirements for the mold and may not be acceptable in some applications.
U.S. Patent No. 5,125,816 is similar to U.S. Patent No. 5,651,998 in that sequential co-injection is achieved by opposing gates on both the mold core and cavity respectively. However, in this arrangement the moveable mold half is fitted with slide cores containing tubular passages for feeding resin to one half of the molded part. These slide. cores move via hydraulic cylinders to define secondary mold cavities, which arc in turn filled by gates on the opposing mold half. This system suffers from disadvantages due to its complexity, the additional mold hardware requirements, including the aforementioned slide cores and additional injection nozzles; and the need for special manufacturing attention due to tight tolerances.
U.S. Patent No. 3,873,656 shows a co-injection apparatus wherein at least two plastics are injected into a mold cavity through different gates, using a valve gating system. This design is only suitable for molding very large plastic articles.
Also, the hot runner system taught does not have the capability for allowing separate temperature control of the different resin types, which inherently limits the variety of resins that can be used together in one system. Furthermore, since the gates are far apart from one another, the flow of each resin will not be synunetrical throughout the part, but instead will be biased in the area of the gate.
U. S. Patent No. 4,289,191 shows injection molding of molten wax into a precision metal die, wherein hollow parts are molded to extremely tight tolerances of 10.012 mm. The wax stream flows from a nozzle having a central bore to a cavity or space formed between the nozzle tip, which has a relief channel, and the socket on the -S-exterior of the die, and then into two or more separate spore ports that feed into the mold cavity. Control of wax flow is accomplished by a retractable plunger in the nozzle which functions like a conventional valve stern. Although more than one spree port is employed to supply material to the mold, tlurse- ports are downstream the valve in the nozzle. Also, the valve stem obstructs the melt flow by being in the center of the melt stream, leading to weld lines. Finally, no provision is made for two or more separate resins to be injected through the two or more spree ports, so this method cannot be used for co-injection Pm'Po~s.
U.S. Patent No. 5,645,874 shows a multiple gate nozzle in which each nozzle associated with a respective gate is equipped with an individual heater to allow independent thermal gating. In this arrangement, a central flow passage feels a plurality of radially extending branch passages leading to each respective gate, and as such, cannot accommodate multiple sources of resin or even sequential melt flow, and therefore cannot be used for co-injection purposes.
U.S. Patent No. 4,702,686 shows a nozzle vvhercin a tapered plate divides a central flow channel into two partial channels prior to the nozzle tip and gate. This nozzle cannot accommodate the separate, different, resin sources require for coinjection purposes.
Summary of The Invention It is an object of the present invention to provide an novel apparatus and method for injecting at least two plastic materials into a mold cavity which obviates or mitigates at least one of the disadvantages of the prior art.
According to a first aspect of the present invention, tta~re is provided a method of co-injecting at least two different plastic materials to form a mufti-layer molded product -b using a hot runner injection molding machine with a separate channel for each material, each channel having an end in communication with a separate gate for feeding an injection mold, the method comprising:
(f) heating the plastic materials in their separate channels or storage areas;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gate into the injection mold and preventing further flow of material from the first channel;
(iii) injecting a selected amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
(iv) injecting a selected amount of a third material, said third material being selectod from one of said first plastic material and any other plastic material, said third material being injectod from its respective channel via its respective gate, said respective gate being separated from said second gate by a gate separating means; and (v) moving a valve stem forward to close each said gate.
According to another aspect of the present invention, there is provided a method of co-injecting at least two different plastic materials to form an article having abutting portions of said different plastic materials using a hot runner injection molding machine with a separate channel for each different plastic material, each channel having an end in communication with a respective separate gate for feeding an injection mold, comprising the steps of (f) heating each different plastic material in its respective separate channel;
(ii) injecting a metered amount of a first plastic material from a first channel through a first gate into the injection mold and simultaneously injecting a metered amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
-'-(iii) injecting a metered amount of a plastic material into the injection mold from its respective individual channel through its respective gate; and (iv) moving a valve stem to block all gates leading into the injection mold.
According to another aspect of the present invention, there is provided a method of co-injecting at least two different plastic materials to form a mufti-layer molded product employing a hot runner injection molding machine with a ssparate channel for each material, each channel having an exit in communication with a eve separate gate for feeding an injection mold, the method comprising the steps of (f) heating the plastic materials in their separate channels;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gatc into the injection mold and inhibiting further flow of material from said;
(iii) injecting a selected auiount of a second material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means comprising a protrusion that engages a valve stem to support said valve stem;
(iv) injecting a selected amount of a third material, said third matexial comprising at least one of said first material and another material, said third material being injected from its respective channel and its respective gate into said injection mold;
and (v) moving said valve stem to close at least one of said gates, each gate which is not closed by said valve stem being gated by thermal shut-off to inhibit the flow of plastic into the mold.
According to yet another aspect of the present invention, there is provided a hot runner injection molding apparatus for co-injecting at least two plastic materials into a forming mold, comprising:
a separate channel for each of said at least two plastic materials;
-g-a separate heating means for each of said separate channels;
a separate gate for each of said at least two plastic materials, each said gate being in communication with a corresponding one of said separate channels;
a valve stem movable between a first position wherein each said separate gate is open and a second position wherein each said separate gate is closed; and a gate separating means comprising a protrusion separating each said separate gate from each other said separate gate, said protrusion co-operating with said valve stem to inhibit deflection thereof.
According to yet another aspect of the prat invention, there is providod a hot runner injection molding apparahis for co-injecting at least two different plastic materials through separate channels to farm a mufti-layer moldod product, each separate channel being independently heated and having an end in communication with a respective separate gate entrance into a forming mold, a gate separating means to prevent intermixing of the different plastic materials prior to exit at the gates, and a valve stem capable of longitudinal movement to permit and inhibit the flow of the different plastic materials through said gates, said gate separating means engaging a portion of said valve stem to inhibit lateral deflection thereof.
The present invention provides a nozzle for plastic injection molding machines whereby flow disturbances and the resulting weld lines, which normally occur with known valve gate systems, are reduced. Further, the present invention provides an injection system and method that employs relatively simple nozzle and hot runner designs. The present invention also provides a space-efficient, mufti-material injection 2S system for efficiently molding a plurality of articles in a mufti-cavity mold. The present invention also provides an injection system and method wherein gates of different sizes can be accommodated in a single injection nozzle, each gate size being self according to the viscosity of the particular plastic material flowing through it.
_g_ The present invention provides a novel method for runnerless injection molding, provided with a valve gate assembly, including at least two melt stmams separated at the edge of the mold cavity by a gate separating means, a valve stem that is reciprocally movable and at least two gates that are opened and closed by the valve stem.
Brief Description of T6e Dnwiog~
The p~tsent invention will now be describe, by way of example only, with reference to the attached Figures, wl~in:
Figure 1 is a sectional view of a hot n~nneer-nozzle assembly for a mold cavity wherein two separate plastic materials fed to the nozzle tip and controlled by a single valve stem;
Figure 2 is an expanded view of the nozzle assembly of Figure 1;
Figure 3 is a set of sectional views of a molded article detailing the layesod wall structure after first, second, and third shots of plastic material;
Figure 4a is an end view of a nozzle assembly with three gates in accordance with the present invention;
Figure 4b is a section of the nozzle assembly of Figure 4a, taken along line A-A
of Figure 4a;
Figure 4c is a section of the nozzle assembly of Figure 4a, taken along line B-B of Figure 4a;
Figure Sa is a side view of a valve stem for the nozzle assembly of Figure 4a;
and Figure Sb is an end view of the valve stem of Figure Sa.
Description Of the Preferred Embodiments In Figure 1 an embodiment of a valve gate assembly and injection nozzle in accordance with the present invention is indicated generally at 20 which is, in this embodiment of the present invention, a co-injection hot nuuxt system which accommodates two plastic materials. One plastic material is provided from a source comprising extruder 24 and the other plastic material is provic~d from a separate extr~a~
(not shown). As used herein, different plastic materials is not intended to be limited to different material compositions, such as PET versus EVOH, but can also comprise, without limitation, materials with generally the same composition but different characteristics, such as PET in different colours or virgin PET versus recycled PET, foamed plastic materials versus non-foamed plastics, etc.
In this example, the portion of the hot nmner system connected to extruder 24 is maintained at a temperatiure rrangir ; from 500° to 550°F, the optimum processing temperatim for a thermoplastic resin such as polyethylene teraphth,alate, or PET, by suitable heaters in weU-known fashioa. Conversely, the portion of the system, illustrated in broken lines, which is connected to the second extn~der is maintained at a different temperature, such as the range from 400° to 440°F, the optimum processing tearperature for a thermoplastic resin such as EVOH. It is to be noted that the plastic materials selected and their optimum processing temperatures are merely examples of the present invention and their use in the present description is not intended as a limitation of the present invention.
A c~tral manifold block 51 maintaira~d at an operating temperature ranging from 500 to 550°F by heating elements 52 and receives plasticized resin from extender 24 through channels 53 and 54. A spool, or rotary, valve 56 is in circuit with channel 54 and operated by link mechanism 57, and controls the charging of reservoir 58 of the shooting pot, or injection cylinder, 59 equipped with an injection piston or charging piston 61.
Valve 56 is formed with a transverse throughbore 62 and is shown in the close position in Figure 1.
With reference now to Figures 1 and 2, reservoir 58 communicates with a nozzle assembly 64 via channel 63. Htating elements 52 maintain the desired processing temperature of channel 63 as the PET or other plastic material progresses through to channel 90 of nozzle assembly 64 to a gate 76a. As shown, gate 76a is separated from an adjacent gate 76b by a gate separating means. In a preferred aspect of the present invention, the gate separating means is in the form of a protrusion 86 that partially overlaps. central valve stem 83, which is shown in the retracted position in these Figures.
This partial overlap of valve stem 83 and protrusion inhibits any lateral aligannent problams that might ordinarily occur where the stem moves longitudinally backwards and forwards over millions of injection cycles under very high injection pressures exceeding twenty thousand psi. While the overlap between protrusion 86 and steer 83 is preferred, it is not essential to the invention and, as wilt be understood by thox of skill in the art, the gate separating means neod not be a protrusion and can instead be any .suitable barrier between the gates 76.
1S As best seen in Figure 1, a manifold segment 65 is secured to manifold block 51 and is heated by elements 66 to maintain optimum temperature (400° to 440°F) in the hot runner connecting the second extruder (not shown) to channel 67 and to a reservoir 68 of a second shooting pot 69 which is equippod with an injection err charging piston 71. Here again, a spool or rotary valve 72 (shown in the closed position relative to channel 67 in Figure 1 ) controls charging of reservoir 68. In the closed position of the spool valve 72, reservoir 68 communicates with nozzle assembly 64 via a channel 70 through a cut-out ?5. When the spool valve 72 is open, channel 70 is closed and a link mechanism operates to rotate valve 72.
ZS As shown in Figure 2, nozzle assembly 64 includes a central spigot 73 in thermal contact with manifold block 51 immediately adjacent local beating elements 52.
and spigot 73 is preferably fabricated from a good nxtallic thermal conductor such as beryllium copper. Spigot 73 is supported by minimal bearing surfaxs ?7,78, best seen in ~ 12-Figure 2, in a housing 79 and is spacod, from spigot 73 along substantially its entire length to form an insulating air gap 8I. Air gap 81 inhibits conduction of heat from the spigot 73 to the housing 79 to maintain the desirod process temperature, controlled by heating means 82, as the plastic material, such as EVOH, progresses through channel 80 of housing 79 to gate 76b.
The size of each of gates 7Ga and 7bb can be selected as desired, largely independent of the other of gates 76a and 76b, which is advantageous in situations where the viscosities of the different resin streams are significantly different or wherein a significantly larger amount of one material than the otls~ is to be injected in an injection cycle.
Thus, it is apparent that the nozzle and valve gate and the hot rcan~ system of the present invention is effective to maintain different optimum process temperatures appropriate to two diffcrcnt plastic materials from the source of the plastic materials to the nozzle gates.
As will be apparent to those of skill in the art, because the plastic material is supplied to gates 76a and 7fib via channels 80 and 90, respectively, the plastic. materials do not contact the majority of stem 83 and thus wear of stem 83 is reduced in comparison to conventional designs.
A preferred method of operation will now be described with reference to the PET
and EVOH example described above. To prime the hot runner system initially, extruder 24 and the second extruder, including their respective co-operating shooting pots 59 and 69 are purged and the extruders are moved into operative position relative to their respective manifolds. With valve stem 83 and spool , valves 56 and 72 in the open position, shooting pot reservoirs 58 and 68 are charged with PET and EYOH
material, respectively. Next, valve stem 83 is closed by a piston 84 and purged resin in the mold cavity is removed.
Thcreafler the mold is closed and clamped, valve stem 83 is opened and the following sequence is perform. First, spool valve 56 is closed and injection piston 61 is advanced until it bottoms at the point indicated by the reference numeral 100, discharging a measured amount of PET into the mold cavity through channel 63 and gate 76a, which is separated from the adjacent gate 76b by a protrusion $G. This constitutes the first shot of PET into the mold cavity, as shown schematically at F in Figure 3.
I0 . .
Piston 61 is held forward (in i~ bottomed position 100) blocking to reservoir 58 to prevent backflow of PET compound from channel 63 into reservoir 58.
That is, the piston 61 is held bottomed to block access to reservoir S8 because upon subsequent operation of piston 7I to inject EVOH, the EVOH injection pressure would have a tendency to displace PET from channel 63 back into reservoir 58.
Next, spool valve 72 is closed to the second extruder and opened to channel 70.
Injection piston 71 is moved until it bottoms at IOI and thus discharges a measured amount of EVOH into the cavity through channel 70 and gate 76b. This constitutes the first shot of EVOH into the mold cavity (second shot of resin) to develop the three-layer wall as shown schematically at S in Figure 3. As will be apparent, flee volume of the first and second shots of resin is less than the total volume of the mold cavity.
Next channel 70 is closed by appropriate rotation of spool valve 72 and spool valve 56 is opened, allowing extruder 24 to complete the filling of the mold cavity with PET and to pack the molded part while piston 61 remains bottomed, blocking access to reservoir 58. This step constitutes the second shot of PET (third shot of resin) to develop a five-layer wall, as shown schematically at T in Figure 3. Thus, a five-layer wall structure is molded using two resins.
After packing is completed, valve stem 83 is moved forward to the closed position, where it blocks both gates 76a and 76b and piston 61 is now freed to move.
Extruder 24 is operated to recharge reservoir 58 of shooting pot 59, displacing piston 61 until it contacts an injection stop Sa, shown in Figure 1. The positioning of stop Sa controls and measures the amount of PET introduced i~o the reservoir 58.
In similar fashion, the injection stop Sb controls and measures the amount of EVOH introduced into the reservoir 68. During the course of packing the mold cavity, the reservoir 68 is recharged by opening spool valve 72 to allow the second cxt:vder to displace piston 71 until the piston contacts its injection stop Sb, thus charging reservoir 68 with a measured amount of EVOH compound. After a suitable cooling interval, the I S mold is opened and the article is ejby known means. The above cycle is can then be repeated, in continuous, automatic fashion, to generate additional layered articles.
It is also contemplated that articles comprising two or morn layers of materials can be manufactured with the present invention, wherein one of the layers comprises a foamed material. For example, a first plastic material, such as a co-polymer of ethylene and vinyl acetate, can be injected into the mold to form the outer layer of the final article and a second plastic material, such as polyproylene, is then injected to fornn a foamed core. Another layer of the first plastic material can then be injected to seal the foam material between the layers of the first material, much like a sandwich. It is also contemplated that the simultaneous injection of two or more different materials can also be performed with the present invention. This allows, for example, the manufacture of articles of PET-PEN resin blends.
-IS-As will be apparent to those of skill in the art, the present invention need not be limited to nozzle and valve gate assemblies with only two gates and can instead include three or more gates, if desired. In another embodiment of the present invention, shown in Figures 4a, 4b and 4c, a nozzle assembly is shown wherein three ~parate gates food tht~ee different plastic materials into one mold cavity. In this embodiment, the gates 200, 204 and 208, shown in Figure 4a, can be different sizes or the same size (not shown) and each gate is separated from the other two by a protrusion 212, best seen in Figures 4b and 4c.
Figure 4a shows the pie-shaped arrangement of the three nozzle portions 216, and 224 with insulating plates 228a, 228b and 228c, made of a suitable material as will occur to those of skill in the art. Plates 228 separate each nozzle portion 216, 200 ail 224 to maintain different thermal profiles for each plastic material type being carried to each gate 200, 204 and 208, as dictated by the properties of particular materials.
Figures Sa and Sb show a valve stem 240 for the nozzle assembly of Figures 4a, 4b and 4c and the slot 244 which engages protrusion 212, slot 244 being defined between pins 248, 252 and 256 which close respective ones of gates 200, 204 and 208 when stem 240 is advanced toward protrusion 212. While the discussion above has only described a single stem in the nozzle assembly, it is contemplated that in some circumstances more than one valve stem can be employed in the assembly, each valve stem being individually actuated and gating one or more gates.
It is contemplated that in some circumstances both valve gating and thermal can gating can be employed in a single nozzle assembly in accord~e with the present invention. For example, as illustrated in Figure 4a wherein gate 204 is much smaller than gates 200 and 208, one or more gates can be much smaller, relative to the other gates, in the nozzle assembly and these smaller gates can be thermal gated in a conventional manner while larger gates, such as gates 200 and 208, can be valve gated.
It will be understood, of course, that modifications can be made to the embodimcnts of the invention illustrated and described herein without departing from the scope and purview of the invention as defined by the aclaims.
Claims (6)
1. A method of co-injecting at least two different plastic materials to forth an article having abutting portions of said different plastic materials using a hot runner injection molding machine with a separate channel for each different plastic material, each channel having an end in communication with a respective separate gate for feeding an injection mold, comprising the steps of:
(i) heating each different plastic material in its respective separate channel;
(ii) injecting a metered amount of a first plastic material from a first channel through a first gate into the injection mold and simultaneously injecting a metered amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
(iii) injecting a metered amount of a plastic material into the injection mold from its respective individual channel through its respective gate; and (iv) moving a valve stem to block all gates leading into the injection mold.
(i) heating each different plastic material in its respective separate channel;
(ii) injecting a metered amount of a first plastic material from a first channel through a first gate into the injection mold and simultaneously injecting a metered amount of a second plastic material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means;
(iii) injecting a metered amount of a plastic material into the injection mold from its respective individual channel through its respective gate; and (iv) moving a valve stem to block all gates leading into the injection mold.
2. A method of co-injecting at least two different plastic materials to form a multi-layer molded product employing a hot inner injection molding machine with a separate channel for each material, each channel having an exit in communication with a respective separate gate for feeding an injection mold, the method comprising the steps of:
(i) heating the plastic materials in their separate channels;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gate into the injection mold and inhibiting further flow of material from said;
(iii) injecting a selected amount of a second material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means comprising a protrusion that eager a valve stem to support said valve stem; and (iv) moving said valve stem to close at least one of said gates, each gate which is not closed by said valve stem being gated by thermal shut-off to inhibit the flow of plastic into the mold.
(i) heating the plastic materials in their separate channels;
(ii) injecting a selected amount of a first plastic material from a first channel through a first gate into the injection mold and inhibiting further flow of material from said;
(iii) injecting a selected amount of a second material from a second channel through a second gate into the injection mold, said second gate being separated from said first gate by a gate separating means comprising a protrusion that eager a valve stem to support said valve stem; and (iv) moving said valve stem to close at least one of said gates, each gate which is not closed by said valve stem being gated by thermal shut-off to inhibit the flow of plastic into the mold.
3. A method as claimed in claim 1 further comprising the step of, between steps (iii) and (iv), injecting a selected amount of a third material, said third material comprising at least one of said first material and another material, said third material being injected from its respective channel and its respective gate into said injection mold.
4. A hot runner injection molding apparatus for co-injecting at least two plastic materials into a forming mold, comprising:
a separate channel for each of said at least two plastic materials;
a separate heating means for each of said separate channels;
a separate gate for each of said at least two plastic materials, each said gate being in communication with a corresponding one of said separate channels;
a valve stem movable between a fast position wherein each said separate gate is open and a second position wherein each said separate gate is closed; and a protrusion to separate each said separate gate from each other said ate gate, said protrusion co-operating with said valve stem to inhibit deflection thereof.
a separate channel for each of said at least two plastic materials;
a separate heating means for each of said separate channels;
a separate gate for each of said at least two plastic materials, each said gate being in communication with a corresponding one of said separate channels;
a valve stem movable between a fast position wherein each said separate gate is open and a second position wherein each said separate gate is closed; and a protrusion to separate each said separate gate from each other said ate gate, said protrusion co-operating with said valve stem to inhibit deflection thereof.
5. The apparatus as defined in claim 4 in which the forming mold is an injection injection mold.
6. The apparatus as defined in claim 4 further comprising:
means for extruding a skin of the first plastic material; and means for providing a foam interior of the second plastic material inside the skin material to form a foam core.
means for extruding a skin of the first plastic material; and means for providing a foam interior of the second plastic material inside the skin material to form a foam core.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/954,728 | 1997-10-20 | ||
| US08/954,728 US5972258A (en) | 1997-10-20 | 1997-10-20 | Method of using a multiple gating nozzle |
| CA002247867A CA2247867C (en) | 1997-10-20 | 1998-09-24 | Multiple gating nozzle |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002247867A Division CA2247867C (en) | 1997-10-20 | 1998-09-24 | Multiple gating nozzle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2450923A1 true CA2450923A1 (en) | 1999-04-20 |
Family
ID=31716456
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002450923A Withdrawn CA2450923A1 (en) | 1997-10-20 | 1998-09-24 | Multiple gating nozzle |
| CA002462150A Expired - Fee Related CA2462150C (en) | 1997-10-20 | 1998-09-24 | Multiple gating nozzle |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002462150A Expired - Fee Related CA2462150C (en) | 1997-10-20 | 1998-09-24 | Multiple gating nozzle |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA2450923A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012068681A1 (en) | 2010-11-24 | 2012-05-31 | Husky Injection Molding Systems Ltd. | Molding system including shooting-pot assembly and valve assembly in which hold pressure not provided by shooting pot assembly |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108656465A (en) * | 2018-04-24 | 2018-10-16 | 广东伟达智能装备股份有限公司 | Plate rotating device and injection mold in mold |
| US11884791B2 (en) | 2020-03-09 | 2024-01-30 | Nike, Inc. | Footwear component manufacturing system |
-
1998
- 1998-09-24 CA CA002450923A patent/CA2450923A1/en not_active Withdrawn
- 1998-09-24 CA CA002462150A patent/CA2462150C/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012068681A1 (en) | 2010-11-24 | 2012-05-31 | Husky Injection Molding Systems Ltd. | Molding system including shooting-pot assembly and valve assembly in which hold pressure not provided by shooting pot assembly |
| EP2643138A1 (en) * | 2010-11-24 | 2013-10-02 | Husky Injection Molding Systems S.A. | Molding system including shooting-pot assembly and valve assembly in which hold pressure not provided by shooting pot assembly |
| EP2643138A4 (en) * | 2010-11-24 | 2014-10-01 | Husky Injection Molding | Molding system including shooting-pot assembly and valve assembly in which hold pressure not provided by shooting pot assembly |
| US8932507B2 (en) | 2010-11-24 | 2015-01-13 | Husky Injection Molding Systems | Molding system including shooting-pot assembly and valve assembly in which hold pressure not provided by shooting pot assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2462150C (en) | 2008-03-11 |
| CA2462150A1 (en) | 1999-04-20 |
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Legal Events
| Date | Code | Title | Description |
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| AZWI | Withdrawn application |