CA2686188A1 - Improved injection moulding nozzle and tip - Google Patents
Improved injection moulding nozzle and tip Download PDFInfo
- Publication number
- CA2686188A1 CA2686188A1 CA 2686188 CA2686188A CA2686188A1 CA 2686188 A1 CA2686188 A1 CA 2686188A1 CA 2686188 CA2686188 CA 2686188 CA 2686188 A CA2686188 A CA 2686188A CA 2686188 A1 CA2686188 A1 CA 2686188A1
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- Prior art keywords
- tip
- injection moulding
- main member
- nozzle tip
- moulding nozzle
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/278—Nozzle tips
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
An injection moulding nozzle tip is provided which comprises a substantially elongate main member, an inlet provided at a proximal end of the main member, a tapered apex portion provided at a distal end of the main member, one or more outlets provided in the main member between the proximal end and the tapered apex portion, and a fluid flow path between the inlet and the or each outlet.
According to other embodiments, the tip may further comprise a bulbous portion provided between the apex and the one or more outlets, and/or a concavely-shaped apex.
The invention may also be said to consist in an injection moulding nozzle assembly and/or an injection moulding system including the nozzle tip.
According to other embodiments, the tip may further comprise a bulbous portion provided between the apex and the one or more outlets, and/or a concavely-shaped apex.
The invention may also be said to consist in an injection moulding nozzle assembly and/or an injection moulding system including the nozzle tip.
Description
IMPROVED INJECTION MOULDING NOZZLE AND TIP
Field This invention relates to nozzles and nozzle tips for injection moulding of plastic, and in particular, but not exclusively, to a "hot runner" type of nozzle.
Background In "hot runner" style injection moulding, molten plastic is injected into a mould cavity through a heated nozzle. The plastic flows through a tip, which is typically made from a relatively highly thermally conductive material. The heated tip itself is typically spaced apart from the mould to avoid direct contact between the tip and the cooled mould, and is positioned relative to the gate opening of the mould by a locating means such as a locating nut. The nut is often made from a material which has relatively poor thermal conductivity such as titanium, in order to insulate the tip from the mould.
Present designs of nozzles, and in particular nozzle tips, have a number of disadvantages.
Many nozzles of the prior art raise the temperature of the plastic within the nozzle to a peak many tens of degrees higher than the optimum injection temperature in order to ensure that it exits the nozzle at around the correct temperature. This may be particularly undesirable when modern composite plastics are used, as some of these materials may have a relatively narrow range of temperatures (i.e. "operating window") within which the plastic stays molten, but does not degrade.
The temperature of the nozzles of the prior art is monitored and controlled in order to ensure that the temperature of the plastic exiting the nozzle is within a required range.
Field This invention relates to nozzles and nozzle tips for injection moulding of plastic, and in particular, but not exclusively, to a "hot runner" type of nozzle.
Background In "hot runner" style injection moulding, molten plastic is injected into a mould cavity through a heated nozzle. The plastic flows through a tip, which is typically made from a relatively highly thermally conductive material. The heated tip itself is typically spaced apart from the mould to avoid direct contact between the tip and the cooled mould, and is positioned relative to the gate opening of the mould by a locating means such as a locating nut. The nut is often made from a material which has relatively poor thermal conductivity such as titanium, in order to insulate the tip from the mould.
Present designs of nozzles, and in particular nozzle tips, have a number of disadvantages.
Many nozzles of the prior art raise the temperature of the plastic within the nozzle to a peak many tens of degrees higher than the optimum injection temperature in order to ensure that it exits the nozzle at around the correct temperature. This may be particularly undesirable when modern composite plastics are used, as some of these materials may have a relatively narrow range of temperatures (i.e. "operating window") within which the plastic stays molten, but does not degrade.
The temperature of the nozzles of the prior art is monitored and controlled in order to ensure that the temperature of the plastic exiting the nozzle is within a required range.
The temperature variation within the nozzles of the prior art has traditionally been so great that the position of the sensor taking this measurement has been critical in order to achieve a representative measurement.
The plastic material commonly flows out of the tip from one or more outlets at or substantially adjacent a distal end of the tip. In use, pressure forces a small amount of the molten plastic upwards towards the nozzle forming a "bubble" or resin layer to insulate the exposed portion of the tip in the space between the tip, a locating nut engaged therewith, and/or the mould gate, potentially resulting in "hang up"
areas of stagnant plastic. If there is a change in the plastic material being used in the injection moulding system, for example a change in the colour of the plastic, material remaining in this space can contaminate the new plastic for one or more drops since it is not quickly flushed out by the new material. Accordingly, it may be necessary to remove and clean the nozzle thoroughly before changing material.
Due largely to the placement of the outlets at the distal end of the tip, injection moulding tips of the prior art generally have a smaller mass and/or outer surface area than might otherwise be desirable to maintain the temperature of the molten plastic as it is injected into the mould, and may cause unnecessary or undesirable stagnation, circulation or flow paths of the molten plastic.
Furthermore, injection moulding nozzle tips of the prior art have traditionally had a conical shape at the distal end. Any misalignment of the tip with respect to the gate of a mould, in particular if the nozzle is positioned too close to the gate, significantly reduces the spacing between the tip and gate, and thus the size of the opening through which the plastic material is injected into the mould. This can affect the injection pressure and thus the quality of the moulding.
Object of the Invention It is therefore an object of the invention to provide an injection moulding nozzle and/or a nozzle tip which overcomes or ameliorates at least one problem of the nozzles/tips of the prior art, or at least to provide the public with a useful choice.
The plastic material commonly flows out of the tip from one or more outlets at or substantially adjacent a distal end of the tip. In use, pressure forces a small amount of the molten plastic upwards towards the nozzle forming a "bubble" or resin layer to insulate the exposed portion of the tip in the space between the tip, a locating nut engaged therewith, and/or the mould gate, potentially resulting in "hang up"
areas of stagnant plastic. If there is a change in the plastic material being used in the injection moulding system, for example a change in the colour of the plastic, material remaining in this space can contaminate the new plastic for one or more drops since it is not quickly flushed out by the new material. Accordingly, it may be necessary to remove and clean the nozzle thoroughly before changing material.
Due largely to the placement of the outlets at the distal end of the tip, injection moulding tips of the prior art generally have a smaller mass and/or outer surface area than might otherwise be desirable to maintain the temperature of the molten plastic as it is injected into the mould, and may cause unnecessary or undesirable stagnation, circulation or flow paths of the molten plastic.
Furthermore, injection moulding nozzle tips of the prior art have traditionally had a conical shape at the distal end. Any misalignment of the tip with respect to the gate of a mould, in particular if the nozzle is positioned too close to the gate, significantly reduces the spacing between the tip and gate, and thus the size of the opening through which the plastic material is injected into the mould. This can affect the injection pressure and thus the quality of the moulding.
Object of the Invention It is therefore an object of the invention to provide an injection moulding nozzle and/or a nozzle tip which overcomes or ameliorates at least one problem of the nozzles/tips of the prior art, or at least to provide the public with a useful choice.
Further objects of the invention will become apparent from the following description.
Summary of Invention Accordingly in one aspect the invention may broadly be said to consist in an injection moulding nozzle tip comprising:
a substantially elongate main member;
an inlet provided at a proximal end of the main member;
a tapered apex portion provided at a distal end of the main member;
one or more outlets provided in the main member between the proximal end and the tapered apex portion; and a fluid flow path between the inlet and the or each outlet.
Preferably the tapered apex portion comprises the distal end of a bulbous portion of the tip provided at the distal end of the main member, whereupon the one or more outlets are provided between the proximal end and the bulbous portion of the tip.
Preferably the diameter of the widest part of the bulbous portion is greater than the diameter of the main member at or adjacent the or each outlet.
Preferably the tapered apex portion has a substantially concave shape, wherein the angle of the outer surface with respect to a main axis of the main member reduces towards the distal end.
Preferably the concave shape comprises a concave cone having an inwardly-curved conical outer surface.
Alternatively the concave shape may comprise a plurality of substantially linear and/or curved surfaces.
Preferably the main member is adapted to engage with a locating nut at or adjacent the distal end, and an interchangeable nozzle body at or adjacent the proximal end, the locating nut being adapted to locate the tip with respect to a mould gate and the nozzle body being adapted to engage with a manifold of an injection moulding system, wherein the tip comprises an integrated injection moulding tip and connector between the nozzle body and the locating nut.
Preferably at least a portion of the proximal end of the main member is adapted for disposal internally of the nozzle body, and at least a portion distal end of the main member is adapted for disposal internally of the locating nut.
Preferably the proximal and distal ends of the main member each comprise a threaded portion adapted to engage with complementary threaded portions of the nozzle body and locating nut, respectively.
Preferably the threaded portions have an external diameter less than that of a central portion of the main member provided between said threaded portions, wherein the central portion has an external surface adapted to contact a heating means.
According to a second aspect, the invention may broadly be said to consist in an injection moulding nozzle assembly comprising an injection moulding nozzle tip according to any one of the preceding statements.
Further aspects of the invention will become apparent from the following description.
Drawing Description:
A number of embodiments of the invention will now be described by way of example with reference to the drawings in which:
Figure 1 is a perspective view of a nozzle including a tip according to the present invention;
Figure 2 is a cross section of an example embodiment of a nozzle according to the invention, also showing two alternative nozzle bodies in addition to that engaged with the tip; and 5 Figure 3 shows a cross section of the distal end of the tip, the locating nut, and the gate to a mould.
Detailed Description of the Drawings Throughout the description like reference numerals will be used to refer to like features in different embodiments.
Referring to Fig. 1, an injection moulding nozzle according to the present invention is shown generally referenced 100.
The nozzle 100 includes a nozzle body 1 with a channel 2 therethrough providing a fluid path between an inlet 2a and an outlet 2b. A tip, substantially comprising the shank or main member 3, is positioned adjacent and engaged with the nozzle body 1. The main member 3 includes a channel 4 therethrough providing a fluid flow path between an inlet 4a at a proximal end and at least one outlet 4b towards a distal end of the tip.
When in the correct position, as shown in Figure 2, the inlet 4a of the tip substantially aligns with the outlet 2b of the nozzle body, so that, in use, molten plastic is able to flow from a manifold or machine nozzle (not shown), through the channels 2 and 4, and then into a mould (not shown) via the one or more outlet apertures 4b provided in the tip. In the illustrated embodiment, two outlet apertures 4b are visible, although the tip may comprise one or more such outlets.
The main member 3 in some embodiments may comprise a tip liner and a sleeve (not shown) as described in PCT Patent Application No. PCT/NZ2007/000094 (published under No. WO 2007/123428) assigned to the assignee of the present application, the contents of which are herein incorporated by reference.
According to the preferred embodiment, however, the main member 3 is provided as a single piece as shown. The nozzle 100 will typically also be provided with a housing or cover (not shown) which is preferably attached to or integral with a heating means such an electrical element in intimate thermal contact with the main member 3, in particular a central portion thereof having a larger diameter and an outer surface which is preferably flush with those of the nozzle body 1 and locating nut 6.
The main member 3 of the tip is in use aligned relative to a mould gate 8 by engagement with a locating means such as a locating nut 6, as shown in detail in Fig. 3. In a preferred embodiment the main member 3 has externally threaded portions to engage a first threaded portion at the proximal end of the main member 3 with the nozzle body 1 and a second threaded portion towards the distal end of the main member 3 for engagement with the locating nut 6, so that the main member extends internally into both the nozzle body 1 and the locating nut 6 at respective ends.
The main member 3 is preferably made from a material which has a high thermal conductivity, typically being higher than the nozzle body I and the locating means 6.
In a preferred embodiment the main member 3 may be made from special wear-resistant materials having a high thermal conductivity several times that of steel, or such other suitable material as may be known to those skilled in the art to have a suitable thermal conductivity and yield temperature. In at least one embodiment the tip is constructed from special materials that are at least approximately three to five times more thermally conductive than the nozzle body 1 and/or the housing.
In one embodiment the main member 3 has at least a central cylindrical external surface of greater diameter than the threaded portions, the central cylindrical surface being provided for intimate thermal contact with the heating means. Therefore, the tip has first and second portions of reduced diameter (which may coincide with the threaded portions as illustrated) adjacent to the inlet and outlet, respectively, and a central portion of increased diameter which contacts the heating means. Heat is thus applied to the tip through the larger diameter central portion of the main member 3, rather than heat being applied at either end of the tip as is the case in certain tips of the prior art. Thus heat loss through to the mould is reduced relative to nozzles in which the heating means extends further towards the outlet of the nozzle, and the high thermal conductivity of the main member 3 allows a high proportion of the heat absorbed from the heating means to flow into the plastic in the flow path 4 along the entire length thereof.
Although the tip is described throughout this document by way of example as having a generally circular cross-section of various diameters along its length, in particular including cylindrical and conical portions, the invention is not limited to such shapes and many variations or modifications are possible without departing from the scope of the invention.
The tip has a sufficient mass that it can act as a thermal reservoir. That is, it has a large thermal capacity compared to the plastic in the flow path 4. If the temperature of the plastic flowing through the tip is momentarily cooler than the required temperature then the main member 3 preferably retains sufficient energy that is able to heat the plastic without a significant drop in the temperature of the tip.
Injection moulding nozzle tips of the prior art typically have a conical tapered apex portion 5 with outlet apertures provided close to the apex and thus the mould gate 8.
However, according to the present invention the outlet apertures 4b are provided at or adjacent the base of the tapered portion 5 further towards the proximal end of the tip than is the case in nozzle tips of the prior art. The outlet apertures 4b may therefore be said to be provided in the main member 3 between the tapered portion 5 and the proximal end of the tip, yet typically in a region of the tip substantially enclosed by the locating nut 6, e.g. substantially adjacent the threaded portion adapted to engage the locating nut 6. The outlet apertures 4b are therefore provided at the "top" of the cavity or bubble area between the tip and the locating nut 6 where a bubble or resin layer insulating the tip from the mould forms in use, providing a substantially continuous fluid flow path along the full length of the bubble area or cavity between the tip and locating nut 6, as shown in Fig. 1. This encourages continual flushing of the molten plastic and eliminates or at least minimizes "hang up"
areas where plastic may stagnate or circulate.
Summary of Invention Accordingly in one aspect the invention may broadly be said to consist in an injection moulding nozzle tip comprising:
a substantially elongate main member;
an inlet provided at a proximal end of the main member;
a tapered apex portion provided at a distal end of the main member;
one or more outlets provided in the main member between the proximal end and the tapered apex portion; and a fluid flow path between the inlet and the or each outlet.
Preferably the tapered apex portion comprises the distal end of a bulbous portion of the tip provided at the distal end of the main member, whereupon the one or more outlets are provided between the proximal end and the bulbous portion of the tip.
Preferably the diameter of the widest part of the bulbous portion is greater than the diameter of the main member at or adjacent the or each outlet.
Preferably the tapered apex portion has a substantially concave shape, wherein the angle of the outer surface with respect to a main axis of the main member reduces towards the distal end.
Preferably the concave shape comprises a concave cone having an inwardly-curved conical outer surface.
Alternatively the concave shape may comprise a plurality of substantially linear and/or curved surfaces.
Preferably the main member is adapted to engage with a locating nut at or adjacent the distal end, and an interchangeable nozzle body at or adjacent the proximal end, the locating nut being adapted to locate the tip with respect to a mould gate and the nozzle body being adapted to engage with a manifold of an injection moulding system, wherein the tip comprises an integrated injection moulding tip and connector between the nozzle body and the locating nut.
Preferably at least a portion of the proximal end of the main member is adapted for disposal internally of the nozzle body, and at least a portion distal end of the main member is adapted for disposal internally of the locating nut.
Preferably the proximal and distal ends of the main member each comprise a threaded portion adapted to engage with complementary threaded portions of the nozzle body and locating nut, respectively.
Preferably the threaded portions have an external diameter less than that of a central portion of the main member provided between said threaded portions, wherein the central portion has an external surface adapted to contact a heating means.
According to a second aspect, the invention may broadly be said to consist in an injection moulding nozzle assembly comprising an injection moulding nozzle tip according to any one of the preceding statements.
Further aspects of the invention will become apparent from the following description.
Drawing Description:
A number of embodiments of the invention will now be described by way of example with reference to the drawings in which:
Figure 1 is a perspective view of a nozzle including a tip according to the present invention;
Figure 2 is a cross section of an example embodiment of a nozzle according to the invention, also showing two alternative nozzle bodies in addition to that engaged with the tip; and 5 Figure 3 shows a cross section of the distal end of the tip, the locating nut, and the gate to a mould.
Detailed Description of the Drawings Throughout the description like reference numerals will be used to refer to like features in different embodiments.
Referring to Fig. 1, an injection moulding nozzle according to the present invention is shown generally referenced 100.
The nozzle 100 includes a nozzle body 1 with a channel 2 therethrough providing a fluid path between an inlet 2a and an outlet 2b. A tip, substantially comprising the shank or main member 3, is positioned adjacent and engaged with the nozzle body 1. The main member 3 includes a channel 4 therethrough providing a fluid flow path between an inlet 4a at a proximal end and at least one outlet 4b towards a distal end of the tip.
When in the correct position, as shown in Figure 2, the inlet 4a of the tip substantially aligns with the outlet 2b of the nozzle body, so that, in use, molten plastic is able to flow from a manifold or machine nozzle (not shown), through the channels 2 and 4, and then into a mould (not shown) via the one or more outlet apertures 4b provided in the tip. In the illustrated embodiment, two outlet apertures 4b are visible, although the tip may comprise one or more such outlets.
The main member 3 in some embodiments may comprise a tip liner and a sleeve (not shown) as described in PCT Patent Application No. PCT/NZ2007/000094 (published under No. WO 2007/123428) assigned to the assignee of the present application, the contents of which are herein incorporated by reference.
According to the preferred embodiment, however, the main member 3 is provided as a single piece as shown. The nozzle 100 will typically also be provided with a housing or cover (not shown) which is preferably attached to or integral with a heating means such an electrical element in intimate thermal contact with the main member 3, in particular a central portion thereof having a larger diameter and an outer surface which is preferably flush with those of the nozzle body 1 and locating nut 6.
The main member 3 of the tip is in use aligned relative to a mould gate 8 by engagement with a locating means such as a locating nut 6, as shown in detail in Fig. 3. In a preferred embodiment the main member 3 has externally threaded portions to engage a first threaded portion at the proximal end of the main member 3 with the nozzle body 1 and a second threaded portion towards the distal end of the main member 3 for engagement with the locating nut 6, so that the main member extends internally into both the nozzle body 1 and the locating nut 6 at respective ends.
The main member 3 is preferably made from a material which has a high thermal conductivity, typically being higher than the nozzle body I and the locating means 6.
In a preferred embodiment the main member 3 may be made from special wear-resistant materials having a high thermal conductivity several times that of steel, or such other suitable material as may be known to those skilled in the art to have a suitable thermal conductivity and yield temperature. In at least one embodiment the tip is constructed from special materials that are at least approximately three to five times more thermally conductive than the nozzle body 1 and/or the housing.
In one embodiment the main member 3 has at least a central cylindrical external surface of greater diameter than the threaded portions, the central cylindrical surface being provided for intimate thermal contact with the heating means. Therefore, the tip has first and second portions of reduced diameter (which may coincide with the threaded portions as illustrated) adjacent to the inlet and outlet, respectively, and a central portion of increased diameter which contacts the heating means. Heat is thus applied to the tip through the larger diameter central portion of the main member 3, rather than heat being applied at either end of the tip as is the case in certain tips of the prior art. Thus heat loss through to the mould is reduced relative to nozzles in which the heating means extends further towards the outlet of the nozzle, and the high thermal conductivity of the main member 3 allows a high proportion of the heat absorbed from the heating means to flow into the plastic in the flow path 4 along the entire length thereof.
Although the tip is described throughout this document by way of example as having a generally circular cross-section of various diameters along its length, in particular including cylindrical and conical portions, the invention is not limited to such shapes and many variations or modifications are possible without departing from the scope of the invention.
The tip has a sufficient mass that it can act as a thermal reservoir. That is, it has a large thermal capacity compared to the plastic in the flow path 4. If the temperature of the plastic flowing through the tip is momentarily cooler than the required temperature then the main member 3 preferably retains sufficient energy that is able to heat the plastic without a significant drop in the temperature of the tip.
Injection moulding nozzle tips of the prior art typically have a conical tapered apex portion 5 with outlet apertures provided close to the apex and thus the mould gate 8.
However, according to the present invention the outlet apertures 4b are provided at or adjacent the base of the tapered portion 5 further towards the proximal end of the tip than is the case in nozzle tips of the prior art. The outlet apertures 4b may therefore be said to be provided in the main member 3 between the tapered portion 5 and the proximal end of the tip, yet typically in a region of the tip substantially enclosed by the locating nut 6, e.g. substantially adjacent the threaded portion adapted to engage the locating nut 6. The outlet apertures 4b are therefore provided at the "top" of the cavity or bubble area between the tip and the locating nut 6 where a bubble or resin layer insulating the tip from the mould forms in use, providing a substantially continuous fluid flow path along the full length of the bubble area or cavity between the tip and locating nut 6, as shown in Fig. 1. This encourages continual flushing of the molten plastic and eliminates or at least minimizes "hang up"
areas where plastic may stagnate or circulate.
The position of the outlet apertures 4b means that the tapered portion of the tip, absent of any channel 4 or outlets 4b, also has the advantage of having a greater mass adjacent the mould gate and therefore may better regulate the temperature of the molten plastic as it is injected into the mould. It also aids in creating a unified melt flow since it allows greater time/distance for the melt flows from each outlet 4b to consolidate before reaching the gate.
According to a preferred embodiment, the tapered portion 5 comprises the distal end of an enlarged or bulbous portion 7 of the tip provided at or towards the distal end of the main member 3, wherein the one or more outlets 4b are provided between the proximal end and the bulbous portion 7 of the tip. The bulbous portion 7 is thus provided between the or each outlet aperture 4b and the tapered portion 5, and comprises a portion of the tip which has a diameter greater than that of the main member 3 at or adjacent the outlet apertures 4b. The tip therefore widens towards the distal end of the tip past the or each outlet 4b before narrowing to a point in the tapered apex portion 5.
The bulb is preferably shaped to create a cavity or melt flow area between the tapered apex portion 5 and the gate 8 having a relatively long constant section that decreases in diameter, aiding to unify the melt before it exits the gate, thus reducing flow lines. At least a part of the tapered portion 5 may therefore be shaped to substantially match the contours of the mould gate 5 adjacent the apex.
The increased mass of the bulb not only helps retain heat in the tip, in particular at the apex adjacent the gate, while also increasing the outer surface area and friction for improved heat conductance, thus regulating the temperature of the molten plastic material after leaving the outlet aperture(s) 4b, but also occupies a substantial part of the gate chamber to such an extent that undue pressure losses are avoided. The bulbous shape of the tip downstream from the outlet apertures 4b also helps guide the melt flow as it sweeps most of the plastic around the enlarged portion to minimise circulation in the space between the tip and locating nut 6 and/or mould gate.
According to a preferred embodiment, the tapered portion 5 comprises the distal end of an enlarged or bulbous portion 7 of the tip provided at or towards the distal end of the main member 3, wherein the one or more outlets 4b are provided between the proximal end and the bulbous portion 7 of the tip. The bulbous portion 7 is thus provided between the or each outlet aperture 4b and the tapered portion 5, and comprises a portion of the tip which has a diameter greater than that of the main member 3 at or adjacent the outlet apertures 4b. The tip therefore widens towards the distal end of the tip past the or each outlet 4b before narrowing to a point in the tapered apex portion 5.
The bulb is preferably shaped to create a cavity or melt flow area between the tapered apex portion 5 and the gate 8 having a relatively long constant section that decreases in diameter, aiding to unify the melt before it exits the gate, thus reducing flow lines. At least a part of the tapered portion 5 may therefore be shaped to substantially match the contours of the mould gate 5 adjacent the apex.
The increased mass of the bulb not only helps retain heat in the tip, in particular at the apex adjacent the gate, while also increasing the outer surface area and friction for improved heat conductance, thus regulating the temperature of the molten plastic material after leaving the outlet aperture(s) 4b, but also occupies a substantial part of the gate chamber to such an extent that undue pressure losses are avoided. The bulbous shape of the tip downstream from the outlet apertures 4b also helps guide the melt flow as it sweeps most of the plastic around the enlarged portion to minimise circulation in the space between the tip and locating nut 6 and/or mould gate.
The locating means (e.g. locating nut 6) may, if required, have a lower thermal conductivity than the tip to insulate the tip from the mould and may, for example, be made from steel or titanium. However, because the tip transfers heat so well to the flow path 4 and molten plastic flowing therethrough, it is not generally necessary to provide a locating means having a relatively low thermal conductivity. In some embodiments a more conductive locating means may be used to assist in dissipating the heat generated by shear as the plastic leaves the outlet aperture(s).
Those skilled in the art will recognize the circumstances in which the heat generated by shear is likely to require the use of a locating means which has relatively good thermal conductivity.
According to at least one embodiment of the invention, the outer surfaces of the tapered apex portion of the tip have a substantially concave cross-section in the generally longitudinal direction, wherein the angle of the outer surface of the tapered apex portion with respect to the main or longitudinal axis of the elongate main member 3 reduces towards the distal end of the tip. This concave shape may comprise a concave cone having an inwardly-curved generally conical outer surface, or may alternatively comprise any other suitable shape or shapes having a reduced angle adjacent the apex. For example, the tapered apex portion of the tip may alternatively resemble a first cone-shaped portion at the apex and having a relatively smaller angle with respect to the longitudinal axis, provided on one or more truncated cone portions having relatively larger angles towards the outlet apertures 4b. Those skilled in the art will appreciate that the concave-shaped tapered apex portion may therefore comprise a plurality of substantially linear and/or curved outer surfaces or cross-sections.
The purpose of the concave tip is to provide an apex area which is relatively small in diameter with respect to the gate of a mould with which the nozzle/tip is engaged in use. Variations in the alignment of the tip with respect to the gate, in particular due to thermal expansion of the tip, will therefore have a reduced affect on the size of the opening through which the plastic material is injected into the mould. The concave tip, as opposed to a standard conical or convex tip, also increases the volume of material that can feed the gate area, thereby reducing shear on the materials and avoiding overheating of the tip during injection. Accordingly, the concave tip, alone or in combination with the aforementioned features, may give rise to improved or more consistent material flows and injection pressure, resulting in reduced 5 manufacturing times and/or improved mould product quality.
As previously described, the injection moulding nozzle tip of the present invention is adapted to engage at opposing ends with a nozzle body 1 and a locating nut 6, preferably by way of externally threaded portions of the main member 3. The nozzle 10 body 1 in turn is adapted to engage with a manifold (not shown) of an injection moulding system which distributes the plastic material to the or each nozzle of the system, while the locating nut 6 also engages or abuts with a mould gate 8 to couple the tip therewith and define a fluid flow path to the mould cavity. The main member 3 therefore preferably forms an integrated tip and connector between the nozzle body 1 and locating nut 6.
Substituting an alternative nozzle body, e.g. nozzle body I la or I lb of Fig.
2, for the nozzle body 1 shown engaged with the main member 3, the tip can be configured for engagement with a range of manifolds and may therefore be easily retrofitted to a number of different injection moulding systems. Thus, any injection moulding system can benefit from the advantages of a tip according to various embodiments of the present invention. Alternatively, or additionally, a tip/connector according to the present invention may be replaced by removing and replacing the tip from the nozzle body 1 and locating nut 6, without the need for necessarily replacing those components.
Those skilled in the art will appreciate that the present invention may therefore be said to consist in an injection moulding tip and/or an injection moulding nozzle, manifold, or system including a tip as described herein.
From the foregoing it will be seen that the present invention provides an injection moulding nozzle and a tip therefor which is capable of improved injection characteristics and heat transfer between a heater and molten plastic flowing through the nozzle. The main member conducts heat from an external surface internally to the fluid flow path and projects internally of the body and the locating means so that heat is transferred efficiently to the molten plastic along the substantial length of the main member, which includes a tapered apex beyond one or more outlet apertures to contact and transfer heat to the plastic prior to injection into the mould.
Unless the context clearly requires otherwise, throughout the description, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".
Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Furthermore, where reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are herein incorporated as if individually set forth.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Those skilled in the art will recognize the circumstances in which the heat generated by shear is likely to require the use of a locating means which has relatively good thermal conductivity.
According to at least one embodiment of the invention, the outer surfaces of the tapered apex portion of the tip have a substantially concave cross-section in the generally longitudinal direction, wherein the angle of the outer surface of the tapered apex portion with respect to the main or longitudinal axis of the elongate main member 3 reduces towards the distal end of the tip. This concave shape may comprise a concave cone having an inwardly-curved generally conical outer surface, or may alternatively comprise any other suitable shape or shapes having a reduced angle adjacent the apex. For example, the tapered apex portion of the tip may alternatively resemble a first cone-shaped portion at the apex and having a relatively smaller angle with respect to the longitudinal axis, provided on one or more truncated cone portions having relatively larger angles towards the outlet apertures 4b. Those skilled in the art will appreciate that the concave-shaped tapered apex portion may therefore comprise a plurality of substantially linear and/or curved outer surfaces or cross-sections.
The purpose of the concave tip is to provide an apex area which is relatively small in diameter with respect to the gate of a mould with which the nozzle/tip is engaged in use. Variations in the alignment of the tip with respect to the gate, in particular due to thermal expansion of the tip, will therefore have a reduced affect on the size of the opening through which the plastic material is injected into the mould. The concave tip, as opposed to a standard conical or convex tip, also increases the volume of material that can feed the gate area, thereby reducing shear on the materials and avoiding overheating of the tip during injection. Accordingly, the concave tip, alone or in combination with the aforementioned features, may give rise to improved or more consistent material flows and injection pressure, resulting in reduced 5 manufacturing times and/or improved mould product quality.
As previously described, the injection moulding nozzle tip of the present invention is adapted to engage at opposing ends with a nozzle body 1 and a locating nut 6, preferably by way of externally threaded portions of the main member 3. The nozzle 10 body 1 in turn is adapted to engage with a manifold (not shown) of an injection moulding system which distributes the plastic material to the or each nozzle of the system, while the locating nut 6 also engages or abuts with a mould gate 8 to couple the tip therewith and define a fluid flow path to the mould cavity. The main member 3 therefore preferably forms an integrated tip and connector between the nozzle body 1 and locating nut 6.
Substituting an alternative nozzle body, e.g. nozzle body I la or I lb of Fig.
2, for the nozzle body 1 shown engaged with the main member 3, the tip can be configured for engagement with a range of manifolds and may therefore be easily retrofitted to a number of different injection moulding systems. Thus, any injection moulding system can benefit from the advantages of a tip according to various embodiments of the present invention. Alternatively, or additionally, a tip/connector according to the present invention may be replaced by removing and replacing the tip from the nozzle body 1 and locating nut 6, without the need for necessarily replacing those components.
Those skilled in the art will appreciate that the present invention may therefore be said to consist in an injection moulding tip and/or an injection moulding nozzle, manifold, or system including a tip as described herein.
From the foregoing it will be seen that the present invention provides an injection moulding nozzle and a tip therefor which is capable of improved injection characteristics and heat transfer between a heater and molten plastic flowing through the nozzle. The main member conducts heat from an external surface internally to the fluid flow path and projects internally of the body and the locating means so that heat is transferred efficiently to the molten plastic along the substantial length of the main member, which includes a tapered apex beyond one or more outlet apertures to contact and transfer heat to the plastic prior to injection into the mould.
Unless the context clearly requires otherwise, throughout the description, the words "comprise", "comprising", and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of "including, but not limited to".
Although this invention has been described by way of example and with reference to possible embodiments thereof, it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention. The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features. Furthermore, where reference has been made to specific components or integers of the invention having known equivalents, then such equivalents are herein incorporated as if individually set forth.
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Claims (11)
1. An injection moulding nozzle tip comprising:
a substantially elongate main member;
an inlet provided at a proximal end of the main member;
a tapered apex portion provided at a distal end of the main member;
one or more outlets provided in the main member between the proximal end and the tapered apex portion; and a fluid flow path between the inlet and the or each outlet.
a substantially elongate main member;
an inlet provided at a proximal end of the main member;
a tapered apex portion provided at a distal end of the main member;
one or more outlets provided in the main member between the proximal end and the tapered apex portion; and a fluid flow path between the inlet and the or each outlet.
2. The injection moulding nozzle tip of claim 1, wherein the tapered apex portion comprises the distal end of a bulbous portion of the tip provided at the distal end of the main member, whereupon the one or more outlets are provided between the proximal end and the bulbous portion of the tip.
3. The injection moulding nozzle tip of claim 2, wherein the diameter of the widest part of the bulbous portion is greater than the diameter of the main member at or adjacent the or each outlet.
4. The injection moulding nozzle tip of any one of claims 1 to 3, wherein the tapered apex portion has a substantially concave shape, whereby the angle of the outer surface of the tapered apex portion with respect to a longitudinal axis of the main member is reduced towards the distal end.
5. The injection moulding nozzle tip of claim 4, wherein the concave shape comprises a concave cone having an inwardly-curved conical outer surface.
6. The injection moulding nozzle tip of claim 4, wherein the concave shape comprises a plurality of distinct substantially linear or curved surfaces.
7. The injection moulding nozzle tip of any one of claims 1 to 6, wherein the main member is adapted to engage with a locating nut at or adjacent the distal end, and an interchangeable nozzle body at or adjacent the proximal end, the locating nut being adapted to locate the tip with respect to a mould gate and the nozzle body being adapted to engage with a manifold of an injection moulding system, wherein the tip comprises an integrated injection moulding tip and connector between the nozzle body and the locating nut.
8. The injection moulding nozzle tip of any one of claims 1 to 7, wherein at least a portion of the proximal end of the main member is adapted for disposal internally of the nozzle body, and at least a portion of the distal end of the main member is adapted for disposal internally of the locating nut.
9. The injection moulding nozzle tip of any one of claims 8 to 9, wherein the proximal and distal ends of the main member each comprise a threaded portion adapted to engage with complementary internal threaded portions of the nozzle body and locating nut, respectively.
10. The injection moulding nozzle tip of claim 9, wherein the threaded portions have an external diameter less than that of a central portion of the main member provided between said threaded portions, wherein the central portion has an external surface adapted to contact a heating means.
11. An injection moulding nozzle assembly comprising an injection moulding nozzle tip according to any one of the preceding statements.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2686188 CA2686188A1 (en) | 2009-11-20 | 2009-11-20 | Improved injection moulding nozzle and tip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2686188 CA2686188A1 (en) | 2009-11-20 | 2009-11-20 | Improved injection moulding nozzle and tip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2686188A1 true CA2686188A1 (en) | 2011-05-20 |
Family
ID=44063353
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2686188 Abandoned CA2686188A1 (en) | 2009-11-20 | 2009-11-20 | Improved injection moulding nozzle and tip |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2686188A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11185874B2 (en) * | 2018-07-11 | 2021-11-30 | Phoenix Closures, Inc. | Nozzle tips with neck portions for reduced cleaning times |
| WO2024210852A3 (en) * | 2023-04-04 | 2025-01-02 | Solen Cikolata Gida Sanayi Ve Ticaret Anonim Sirketi | Filling injector for the production of filled biscuit |
-
2009
- 2009-11-20 CA CA 2686188 patent/CA2686188A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11185874B2 (en) * | 2018-07-11 | 2021-11-30 | Phoenix Closures, Inc. | Nozzle tips with neck portions for reduced cleaning times |
| WO2024210852A3 (en) * | 2023-04-04 | 2025-01-02 | Solen Cikolata Gida Sanayi Ve Ticaret Anonim Sirketi | Filling injector for the production of filled biscuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |
Effective date: 20121120 |