CA2195907A1 - Injection molding apparatus with cooled core - Google Patents
Injection molding apparatus with cooled coreInfo
- Publication number
- CA2195907A1 CA2195907A1 CA 2195907 CA2195907A CA2195907A1 CA 2195907 A1 CA2195907 A1 CA 2195907A1 CA 2195907 CA2195907 CA 2195907 CA 2195907 A CA2195907 A CA 2195907A CA 2195907 A1 CA2195907 A1 CA 2195907A1
- Authority
- CA
- Canada
- Prior art keywords
- extending
- cooled core
- cooling tube
- core
- cooling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000001746 injection moulding Methods 0.000 title claims abstract description 11
- 238000001816 cooling Methods 0.000 claims abstract description 42
- 239000012809 cooling fluid Substances 0.000 claims abstract description 21
- 239000000155 melt Substances 0.000 description 10
- 229910000990 Ni alloy Inorganic materials 0.000 description 5
- 239000000498 cooling water Substances 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 230000000284 resting effect Effects 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- DMFGNRRURHSENX-UHFFFAOYSA-N beryllium copper Chemical compound [Be].[Cu] DMFGNRRURHSENX-UHFFFAOYSA-N 0.000 description 1
- 238000005219 brazing Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000012943 hotmelt Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- B29C45/72—Heating or cooling
- B29C45/73—Heating or cooling of the mould
- B29C45/7312—Construction of heating or cooling fluid flow channels
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
Injection molding hot runner apparatus having a cooled mold core with a head which extends outwardly from an elongated body. A cooling tube extends centrally in the mold core. A cooling fluid circuit extends from the open front end of the cooling tube outwardly into the head in close proximity with the surrounding cavity. The cooling fluid circuit includes a number of outwardly extending radial bores, each connected to an L-shaped duct leading back into a cylindrical space around the cooling tube.
Description
21 ~5qo7 INJECTION NOLDING APPARATUS WITH cooT.~n CORE
BACKGROUND OF THE INVENTION
This invention relates generally to injection molding and more particularly to hot runner apparatus having improved cooling provided by the circulation of cooling fluid in the enlarged head of an elongated core.
The cycle time of hot runner injection molding systems can be reduced by providing increased cooling to the cavity. Reducing cycle time by even one second is very important in large volume applications such as making closures with millions or even billions of cycles. As seen in U.S. Patent No. 5,094,603 to Gellert which issued March 10, 1992, it is well known to provide the mold with a cooled core by circulating cooling water through a central cooling tube in the core. While this is satisfactory for many applications, there is still a considerable delay in the molding cycle before the mold is opened for ejection 21 95qo7 waiting for the melt to solidify.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome the disadvantages of the prior art by providing a cooled core with an enlarged head through which cooling fluid is circulated to be in close proximity with the surrounding portion of the cavity.
To this end, in one of its aspects, the invention provides injection molding hot runner apparatus having a heated nozzle seated in a cooled mold to convey melt to a gate leading to a cavity. The mold has a cooled core having a central bore and a front portion with an outer surface extending from an elongated body portion. The outer surface of the front portion of the cooled core has one side of a portion of the cavity extending around the front portion of the cooled core. The cooled core has a central cooling tube extending in the central bore of the cooled core with a cylindrical space extending between the cooling tube and the surrounding body portion of the cooled core. The central cooling tube has an open front end inside the front portion of the cooled core, whereby a cooling fluid circuit is provided extending through the cooling tube and along the cylindrical space around the - 2 1 ;~ ~ 9 0 7 cooling tube to cool the cooled core. The improvement comprises the front portion of the cooled core having a head substantially larger in diameter than the body portion of the cooled core and the cooling fluid circuit extending from the front end of the cooling tube outwardly into the head portion to bring the cooling fluid into close proximity with the surrounding portion of the cavity.
Further objects and advantages of the invention will appears from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view showing a portion of a multi-cavity injection molding system showing a cooled core according to one embodiment of the invention, Figure 2 is a larger sectional view of the cooled core seen in Figure 1, Figure 3 is a sectional view taken along line 3-3 in Figure 2, Figure 4 is a partially cut-away isometric view of two parts of the core in position for assembly, Figure 5 is a sectional view of the two parts assembled together for brazing, and Figure 6 is an isometric view similar to Figure 4 showing the two parts of a cooled core according to a ?1 9~07 second embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Reference is first made to Figure 1 which shows a portion of a multi-cavity hot runner injection molding system or apparatus wherein a melt passage 10 branches in a melt distribution manifold 12 to convey hot melt through each heated nozzle 14 to a gate 16 leading to a cavity 18.
While the configuration of the mold 20 depends upon the application, in this case the melt distribution manifold 12 which interconnects the nozzles 14 is mounted between the nozzle retainer plate 22 and the back plate 24 by a central locating ring 26 and insulative and resilient spacer members 28. As can be seen, this provides an insulative air space 30 between the melt distribution manifold 12 ~ which is heated by an integral electrical heating element 32 and the surrounding nozzle retainer plate 22 and back plate 24 which are cooled by pumping cooling water through cooling conduits 34. Each nozzle 14 extends through an opening 36 in the nozzle plate 22 with its rear end 38 abutting against the front surface 40 of the melt distribution manifold 12. It is heated by an electrical heating element 42 which extends around a central bore 44 through which the melt passage 10 extends. The nozzle 14 has a forwardly extending flange portion 46 which sits on 21 95qi~7 a circular seat 48 in the nozzle retainer plate 22 to locate the nozzle 12 with an insulative air space 50 between it and the surrounding mold 20. In this case, a two-piece nozzle seal 52 is mounted in the front end 54 of each nozzle 14 leading to the aligned gate 16.
As also seen in Figure 1, the mold 20 also includes a cavity retainer plate 56 through which holes 58 extend to receive a cavity insert 60 aligned with each nozzle 14. As described in U.S. Patent Number 5,443,381 to Gellert which issued August 22, 1995, the cavity insert 60 has a front surface 62 which is shaped to form one side of the cavity 18. Cooling is provided to each cavity insert 60 by cooling water from an inlet 64 flowing through tortuous passages 66 to an outlet 68.
The other side of the cavity 18 is formed by the outer surface 70 of the front portion or head 72 of a cooled core 74 according to the invention. The front portion or head 74 of the cooled core 76 extends from an elongated cylindrical body portion 76 which is substantially smaller in diameter than the head 72. In the configuration shown, a thin portion 77 of the cavity 18 extends between a cavity ring 78 and a stripper ring 80.
The cavity ring 78 is held in place by a core guide 82 which extends around the body portion 76 of the core 74.
The stripper ring 80 is received in an opening 84 in a 21 ~,qO7 stripper plate 86.
Referring now to Figures 2 and 3, it can be seen that the cooled core 74 has a central bore 88 extending through the cylindrical body portion 76 into the head 72.
A cooling tube 9o extends through the central bore 88 in the cylindrical body portion 76 to an open front end 92 in the head 7Z. The front end 92 of the cooling tube 90 is threaded and screws into the threaded portion 94 of the central bore 88 in the head 72. The cooling tube 90 is sufficiently smaller in diameter than the portion 96 of the central bore 88 through the body portion 76 of the core 74 to provide an elongated cylindrical space 98 between the cooling tube 90 and the surrounding body portion 76 of the cooled core 74. The head 72 of the cooled core 74 has a number of outwardly extending radial bores 100 equally spaced around it. Each radial bore 100 has an outer end 102 and an inner end 104 extending from the central bore 88 adjacent the open front end 92 of the cooling tube 90. In the embodiment shown, the head 72 has eight radial bores 100, but there can be a different number in other embodiments. The head 72 of the cooled core 74 also has an equal number of forwardly extending L-shaped ducts 106, each having a rear end 108 and an inner end 110. The rear end 108 of each L-shaped duct 106 connects with the outer end 102 of one of the radial bores 100 and the inner end - 21 95qO7 110 of each L-shaped duct 106 connects with the cylindrical space 98 between the cooling tube 90 and the surrounding body portion 76 of the cooled core 72. Thus, as shown by the arrows in Figure 2, the core 74 has a circuit 112 for a suitable cooling fluid such as water flowing through the cooling tube 90, radially outward through the radial bores 100, along the head 72 and back in through the L-shaped ducts 106, and along the cylindrical space 98 around the cooling tube 90. Of course, in other embodiments, the direction of flow through the circuit can be the opposite.
Reference is now made to Figures 4 and 5 in describing how the cooled core 74 according to the invention is made. Firstly, an upper and inner piece 114 and a lower and outer piece 116 are machined of a suitable material such as H13 tool steel. In other embodiments, the upper piece 114 can be made of a more thermally conductive material such as a beryllium copper alloy to further improve cooling. As can be seen, in this embodiment the upper piece 114 is made with an upwardly extending stem portion 118 and a cylindrical portion 120 extending forwardly from a larger diameter circular flange portion 122. The cylindrical portion 120 has the radial bores loo extending outwardly from the portion 94 of the central bore 88 in the head 72 which receives the open end 92 of the cooling tube 90. The lower piece 116 is made with the 2i ~ ~07 larger portion 96 of the central bore 88 extending to a first seat 124 which extends outwardly and upwardly to a larger diameter second seat 126. L-shaped grooves 128 are machined in the first seat 124 to form the L-shaped ducts 106 when the two pieces 114, 116 are assembled together.
The first seat 124 is made to fit around the cylindrical portion 120 of the upper piece 114. Similarly, the second seat 126 is made to fit around the flange portion 122 of the upper piece 114. The lower piece 116 is mounted in an upright position and the upper piece 114 is lowered into the position shown in Figure 4 with the cylindrical portion 120 resting on the first seat 124 and the circular flange portion 122 resting on the second seat 126. The lower piece 116 has a pin 132 extending upwardly from the first seat 124 which fits in a matching hole 134 in the cylindrical portion 120 of the upper piece 114 to ensure that the radial bores loo in the upper piece 114 are aligned with the L-shaped grooves 128 in the lower piece.
A quantity of a suitable material such as powdered nickel alloy 130 is poured around the flange portion 122 of the upper piece 114 which has a bevelled rear surface 136 to direct the powder 130 into place. The assembled pieces 114, 116 are then loaded into a vacuum furnace and gradually heated to a temperature of approximately 1925~ F.
which is above the melting temperature of the nickel alloy.
2~' ~5qO7 As the furnace is heated, it is evacuated to a relatively high vacuum to remove substantially all of the oxygen and then partially backfilled with an inert gas such as argon or nitrogen. When the melting point of the nickel alloy is reached, the nickel alloy 130 melts and flows downwardly around the flange portion 122 and between the contacting surfaces of the upper piece 114 and the lower piece 116.
The nickel alloy 130 spreads between them by capillary action to integrally braze the upper and lower pieces 114, 116 together to form an integral core 74. The core 74 is then machined to remove the stem portion 118 and to reduce the distance of the outer surface 70 of the head 72 is from the cooling fluid circuit 112 and the cooling tube 90 is screwed into place in the central bore 88 of the core 74.
While this configuration with the L-shaped grooves 128 being machined in the lower or outer piece 116 provides an optimum combination of structural strength and cooling provided by the proximity of the cooling fluid circuit 112 to the outer surfaces 70 of the head 72, in an alternate embodiment, the L-shaped ducts 106 can be made by machining L-shaped grooves in the upper or inner piece 114 rather than in the lower or outer piece 116. In the embodiment shown, as seen in Figure 2, the cooled core 74 is only one part 138 which is joined to another overlapping conventional part 140 to form an elongated cooled core 74.
q O 7 In this case, the one part 138 is made by the manufacturer and shipped to the mold maker to be brazed or welded to the other part 140. Of course, in another embodiment, the entire cooled core can be made by one party without requiring two parts.
In use, after the system has been assembled as shown in Figure 1, electrical power is applied to the heating elements 32, 42 to heat the manifold 12 and the nozzles 14 to a predetermined operating temperature.
lo Cooling water is also circulated by pumps (not shown) through the cooling conduits 34, the cooling passages 66 in the cavity inserts 60, and the cooling fluid circuits 112 in the mold cores 74 to cool the mold 20. Pressurized melt from a molding machine (not shown) is then introduced according to a predetermined cycle into the central inlet 142 of the melt passage 10 of the manifold 12, from where it flows through the melt bore 44 of each nozzle 14 to fill the cavities 18. After the cavities 18 are full, injection pressure is held momentarily to pack and then released.
After a short cooling period, the mold 20 is opened to eject the product. After ejection, the mold 20 is closed the injection pressure is reapplied to refill the cavities 18. This cycle is repeated in a continuous cycle with a frequency dependent on the size and shape of the cavities 18 and the type of material being molded. Providing the 21 9 ,907 radial bores 100 for the cooling fluid to flow out into the head 72 of the mold core 74 improves cooling and reduces injection cycle time by the close proximity of the cooling circuit 112 to the cavity 18. Providing the L-shaped ducts 106 provides maximum surface contact between the upper and lower pieces 114, 116 and gives the integral mold core 74 the necessary structural strength to withstand injection stresses. The combination of the radial bores 100 and L-shaped ducts 106 ensures turbulent flow of the cooling water through the circuit 112 which further improves cooling efficiency.
Reference is now made to Figure 6 to describe another embodiment of the invention. This embodiment is the same as that described above except that the radial bores 100 extend out to a single L-shaped space 144 extending continuously around between the cylindrical portion 120 of the upper and inner piece 114 and the first seat 124 of the lower and outer piece 116. While this embodiment of the cooled core does not have the same structural strengths as the embodiments described above, it is sufficient for some applications.
While the description of the cold mold core 74 with the cooling fluid circuit 112 extending outwardly into its head 72 has been given with respect to preferred embodiments, it will be evident that various other 2 1 ~5~07 modifications are possible without departing from the scope of the invention as understood by those skilled in the art and as provided in the following claims.
BACKGROUND OF THE INVENTION
This invention relates generally to injection molding and more particularly to hot runner apparatus having improved cooling provided by the circulation of cooling fluid in the enlarged head of an elongated core.
The cycle time of hot runner injection molding systems can be reduced by providing increased cooling to the cavity. Reducing cycle time by even one second is very important in large volume applications such as making closures with millions or even billions of cycles. As seen in U.S. Patent No. 5,094,603 to Gellert which issued March 10, 1992, it is well known to provide the mold with a cooled core by circulating cooling water through a central cooling tube in the core. While this is satisfactory for many applications, there is still a considerable delay in the molding cycle before the mold is opened for ejection 21 95qo7 waiting for the melt to solidify.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome the disadvantages of the prior art by providing a cooled core with an enlarged head through which cooling fluid is circulated to be in close proximity with the surrounding portion of the cavity.
To this end, in one of its aspects, the invention provides injection molding hot runner apparatus having a heated nozzle seated in a cooled mold to convey melt to a gate leading to a cavity. The mold has a cooled core having a central bore and a front portion with an outer surface extending from an elongated body portion. The outer surface of the front portion of the cooled core has one side of a portion of the cavity extending around the front portion of the cooled core. The cooled core has a central cooling tube extending in the central bore of the cooled core with a cylindrical space extending between the cooling tube and the surrounding body portion of the cooled core. The central cooling tube has an open front end inside the front portion of the cooled core, whereby a cooling fluid circuit is provided extending through the cooling tube and along the cylindrical space around the - 2 1 ;~ ~ 9 0 7 cooling tube to cool the cooled core. The improvement comprises the front portion of the cooled core having a head substantially larger in diameter than the body portion of the cooled core and the cooling fluid circuit extending from the front end of the cooling tube outwardly into the head portion to bring the cooling fluid into close proximity with the surrounding portion of the cavity.
Further objects and advantages of the invention will appears from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view showing a portion of a multi-cavity injection molding system showing a cooled core according to one embodiment of the invention, Figure 2 is a larger sectional view of the cooled core seen in Figure 1, Figure 3 is a sectional view taken along line 3-3 in Figure 2, Figure 4 is a partially cut-away isometric view of two parts of the core in position for assembly, Figure 5 is a sectional view of the two parts assembled together for brazing, and Figure 6 is an isometric view similar to Figure 4 showing the two parts of a cooled core according to a ?1 9~07 second embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Reference is first made to Figure 1 which shows a portion of a multi-cavity hot runner injection molding system or apparatus wherein a melt passage 10 branches in a melt distribution manifold 12 to convey hot melt through each heated nozzle 14 to a gate 16 leading to a cavity 18.
While the configuration of the mold 20 depends upon the application, in this case the melt distribution manifold 12 which interconnects the nozzles 14 is mounted between the nozzle retainer plate 22 and the back plate 24 by a central locating ring 26 and insulative and resilient spacer members 28. As can be seen, this provides an insulative air space 30 between the melt distribution manifold 12 ~ which is heated by an integral electrical heating element 32 and the surrounding nozzle retainer plate 22 and back plate 24 which are cooled by pumping cooling water through cooling conduits 34. Each nozzle 14 extends through an opening 36 in the nozzle plate 22 with its rear end 38 abutting against the front surface 40 of the melt distribution manifold 12. It is heated by an electrical heating element 42 which extends around a central bore 44 through which the melt passage 10 extends. The nozzle 14 has a forwardly extending flange portion 46 which sits on 21 95qi~7 a circular seat 48 in the nozzle retainer plate 22 to locate the nozzle 12 with an insulative air space 50 between it and the surrounding mold 20. In this case, a two-piece nozzle seal 52 is mounted in the front end 54 of each nozzle 14 leading to the aligned gate 16.
As also seen in Figure 1, the mold 20 also includes a cavity retainer plate 56 through which holes 58 extend to receive a cavity insert 60 aligned with each nozzle 14. As described in U.S. Patent Number 5,443,381 to Gellert which issued August 22, 1995, the cavity insert 60 has a front surface 62 which is shaped to form one side of the cavity 18. Cooling is provided to each cavity insert 60 by cooling water from an inlet 64 flowing through tortuous passages 66 to an outlet 68.
The other side of the cavity 18 is formed by the outer surface 70 of the front portion or head 72 of a cooled core 74 according to the invention. The front portion or head 74 of the cooled core 76 extends from an elongated cylindrical body portion 76 which is substantially smaller in diameter than the head 72. In the configuration shown, a thin portion 77 of the cavity 18 extends between a cavity ring 78 and a stripper ring 80.
The cavity ring 78 is held in place by a core guide 82 which extends around the body portion 76 of the core 74.
The stripper ring 80 is received in an opening 84 in a 21 ~,qO7 stripper plate 86.
Referring now to Figures 2 and 3, it can be seen that the cooled core 74 has a central bore 88 extending through the cylindrical body portion 76 into the head 72.
A cooling tube 9o extends through the central bore 88 in the cylindrical body portion 76 to an open front end 92 in the head 7Z. The front end 92 of the cooling tube 90 is threaded and screws into the threaded portion 94 of the central bore 88 in the head 72. The cooling tube 90 is sufficiently smaller in diameter than the portion 96 of the central bore 88 through the body portion 76 of the core 74 to provide an elongated cylindrical space 98 between the cooling tube 90 and the surrounding body portion 76 of the cooled core 74. The head 72 of the cooled core 74 has a number of outwardly extending radial bores 100 equally spaced around it. Each radial bore 100 has an outer end 102 and an inner end 104 extending from the central bore 88 adjacent the open front end 92 of the cooling tube 90. In the embodiment shown, the head 72 has eight radial bores 100, but there can be a different number in other embodiments. The head 72 of the cooled core 74 also has an equal number of forwardly extending L-shaped ducts 106, each having a rear end 108 and an inner end 110. The rear end 108 of each L-shaped duct 106 connects with the outer end 102 of one of the radial bores 100 and the inner end - 21 95qO7 110 of each L-shaped duct 106 connects with the cylindrical space 98 between the cooling tube 90 and the surrounding body portion 76 of the cooled core 72. Thus, as shown by the arrows in Figure 2, the core 74 has a circuit 112 for a suitable cooling fluid such as water flowing through the cooling tube 90, radially outward through the radial bores 100, along the head 72 and back in through the L-shaped ducts 106, and along the cylindrical space 98 around the cooling tube 90. Of course, in other embodiments, the direction of flow through the circuit can be the opposite.
Reference is now made to Figures 4 and 5 in describing how the cooled core 74 according to the invention is made. Firstly, an upper and inner piece 114 and a lower and outer piece 116 are machined of a suitable material such as H13 tool steel. In other embodiments, the upper piece 114 can be made of a more thermally conductive material such as a beryllium copper alloy to further improve cooling. As can be seen, in this embodiment the upper piece 114 is made with an upwardly extending stem portion 118 and a cylindrical portion 120 extending forwardly from a larger diameter circular flange portion 122. The cylindrical portion 120 has the radial bores loo extending outwardly from the portion 94 of the central bore 88 in the head 72 which receives the open end 92 of the cooling tube 90. The lower piece 116 is made with the 2i ~ ~07 larger portion 96 of the central bore 88 extending to a first seat 124 which extends outwardly and upwardly to a larger diameter second seat 126. L-shaped grooves 128 are machined in the first seat 124 to form the L-shaped ducts 106 when the two pieces 114, 116 are assembled together.
The first seat 124 is made to fit around the cylindrical portion 120 of the upper piece 114. Similarly, the second seat 126 is made to fit around the flange portion 122 of the upper piece 114. The lower piece 116 is mounted in an upright position and the upper piece 114 is lowered into the position shown in Figure 4 with the cylindrical portion 120 resting on the first seat 124 and the circular flange portion 122 resting on the second seat 126. The lower piece 116 has a pin 132 extending upwardly from the first seat 124 which fits in a matching hole 134 in the cylindrical portion 120 of the upper piece 114 to ensure that the radial bores loo in the upper piece 114 are aligned with the L-shaped grooves 128 in the lower piece.
A quantity of a suitable material such as powdered nickel alloy 130 is poured around the flange portion 122 of the upper piece 114 which has a bevelled rear surface 136 to direct the powder 130 into place. The assembled pieces 114, 116 are then loaded into a vacuum furnace and gradually heated to a temperature of approximately 1925~ F.
which is above the melting temperature of the nickel alloy.
2~' ~5qO7 As the furnace is heated, it is evacuated to a relatively high vacuum to remove substantially all of the oxygen and then partially backfilled with an inert gas such as argon or nitrogen. When the melting point of the nickel alloy is reached, the nickel alloy 130 melts and flows downwardly around the flange portion 122 and between the contacting surfaces of the upper piece 114 and the lower piece 116.
The nickel alloy 130 spreads between them by capillary action to integrally braze the upper and lower pieces 114, 116 together to form an integral core 74. The core 74 is then machined to remove the stem portion 118 and to reduce the distance of the outer surface 70 of the head 72 is from the cooling fluid circuit 112 and the cooling tube 90 is screwed into place in the central bore 88 of the core 74.
While this configuration with the L-shaped grooves 128 being machined in the lower or outer piece 116 provides an optimum combination of structural strength and cooling provided by the proximity of the cooling fluid circuit 112 to the outer surfaces 70 of the head 72, in an alternate embodiment, the L-shaped ducts 106 can be made by machining L-shaped grooves in the upper or inner piece 114 rather than in the lower or outer piece 116. In the embodiment shown, as seen in Figure 2, the cooled core 74 is only one part 138 which is joined to another overlapping conventional part 140 to form an elongated cooled core 74.
q O 7 In this case, the one part 138 is made by the manufacturer and shipped to the mold maker to be brazed or welded to the other part 140. Of course, in another embodiment, the entire cooled core can be made by one party without requiring two parts.
In use, after the system has been assembled as shown in Figure 1, electrical power is applied to the heating elements 32, 42 to heat the manifold 12 and the nozzles 14 to a predetermined operating temperature.
lo Cooling water is also circulated by pumps (not shown) through the cooling conduits 34, the cooling passages 66 in the cavity inserts 60, and the cooling fluid circuits 112 in the mold cores 74 to cool the mold 20. Pressurized melt from a molding machine (not shown) is then introduced according to a predetermined cycle into the central inlet 142 of the melt passage 10 of the manifold 12, from where it flows through the melt bore 44 of each nozzle 14 to fill the cavities 18. After the cavities 18 are full, injection pressure is held momentarily to pack and then released.
After a short cooling period, the mold 20 is opened to eject the product. After ejection, the mold 20 is closed the injection pressure is reapplied to refill the cavities 18. This cycle is repeated in a continuous cycle with a frequency dependent on the size and shape of the cavities 18 and the type of material being molded. Providing the 21 9 ,907 radial bores 100 for the cooling fluid to flow out into the head 72 of the mold core 74 improves cooling and reduces injection cycle time by the close proximity of the cooling circuit 112 to the cavity 18. Providing the L-shaped ducts 106 provides maximum surface contact between the upper and lower pieces 114, 116 and gives the integral mold core 74 the necessary structural strength to withstand injection stresses. The combination of the radial bores 100 and L-shaped ducts 106 ensures turbulent flow of the cooling water through the circuit 112 which further improves cooling efficiency.
Reference is now made to Figure 6 to describe another embodiment of the invention. This embodiment is the same as that described above except that the radial bores 100 extend out to a single L-shaped space 144 extending continuously around between the cylindrical portion 120 of the upper and inner piece 114 and the first seat 124 of the lower and outer piece 116. While this embodiment of the cooled core does not have the same structural strengths as the embodiments described above, it is sufficient for some applications.
While the description of the cold mold core 74 with the cooling fluid circuit 112 extending outwardly into its head 72 has been given with respect to preferred embodiments, it will be evident that various other 2 1 ~5~07 modifications are possible without departing from the scope of the invention as understood by those skilled in the art and as provided in the following claims.
Claims (4)
1. In injection molding hot runner apparatus having at least one heated nozzle seated in a cooled mold to convey melt to a gate leading to a cavity, and at least one cooled core having a central bore and a front portion with an outer surface extending from an elongated body portion, the outer surface of the front portion of the cooled core forming one side of at least a portion of the cavity extending around the front portion of the cooled core, the cooled core having a central cooling tube extending in the central bore of the cooled core with a first cylindrical space extending between the cooling tube and the surrounding body portion of the cooled core, the central cooling tube having an open front end inside the front portion of the cooled core, whereby a cooling fluid circuit is provided extending through the cooling tube and along the first cylindrical space around the cooling tube to cool the cooled core, the improvement wherein;
the front portion of the cooled core comprises a head substantially larger in diameter than the body portion of the cooled core, the cooling fluid circuit extending from the front end of the cooling tube outwardly into the head portion to bring the cooling fluid into close proximity with the surrounding portion of the cavity.
the front portion of the cooled core comprises a head substantially larger in diameter than the body portion of the cooled core, the cooling fluid circuit extending from the front end of the cooling tube outwardly into the head portion to bring the cooling fluid into close proximity with the surrounding portion of the cavity.
2. Injection molding apparatus as claimed in claim 1 wherein the head of the cooled core has a plurality of spaced bores extending radially therein through which the cooling fluid circuit extends, each bore having an inner end and an outer end, the inner end of each bore being located adjacent the open front end of the cooling tube to receive cooling fluid therefrom, the outer end of each bore being connected by rearwardly and inwardly extending cooling fluid flow means to the first cylindrical space extending rearwardly between the cooling tube and the surrounding body portion of the cooled core.
3. Injection molding apparatus as claimed in claim 2 wherein the rearwardly and inwardly extending cooling fluid flow means comprises a plurality of L-shaped ducts, each L-shaped duct having a rear end and an inner end, the rear end being connected to the outer end of one of the radially extending bores, the inner end being connected to the first cylindrical space extending rearwardly between the cooling tube and the surrounding body portion of the cooled core.
4. Injection molding apparatus as claimed in claim 2 wherein the rearwardly and inwardly extending cooling fluid flow means comprises a second cylindrical space extending forwardly to a front end from the outer ends of the radially extending bores and a radially extending space extending inwardly from the front end of the second cylindrical space to the first cylindrical space extending rearwardly between the cooling tube and the surrounding body portion of the cooled core.
Priority Applications (10)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2195907 CA2195907A1 (en) | 1997-01-24 | 1997-01-24 | Injection molding apparatus with cooled core |
| BR9800256A BR9800256A (en) | 1997-01-24 | 1998-01-16 | Refrigerated core injection molding mechanism |
| SG1998000138A SG72784A1 (en) | 1997-01-24 | 1998-01-19 | Injection molding apparatus with cooled core |
| US09/008,995 US5935621A (en) | 1997-01-24 | 1998-01-20 | Injection molding apparatus having a cooled core |
| DE19802387A DE19802387A1 (en) | 1997-01-24 | 1998-01-22 | Die-casting device with cooled core |
| DE69826040T DE69826040T2 (en) | 1997-01-24 | 1998-01-22 | Injection molding device with cooled core |
| AT98101095T ATE275471T1 (en) | 1997-01-24 | 1998-01-22 | INJECTION MOLDING DEVICE WITH COOLED CORE |
| JP01072998A JP4113610B2 (en) | 1997-01-24 | 1998-01-22 | Injection molding apparatus having cooling core |
| EP98101095A EP0855261B1 (en) | 1997-01-24 | 1998-01-22 | Injection molding apparatus with cooled core |
| US09/928,230 USRE38265E1 (en) | 1997-01-24 | 2001-08-10 | Injection molding apparatus having a cooled core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2195907 CA2195907A1 (en) | 1997-01-24 | 1997-01-24 | Injection molding apparatus with cooled core |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2195907A1 true CA2195907A1 (en) | 1998-07-24 |
Family
ID=4159750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2195907 Abandoned CA2195907A1 (en) | 1997-01-24 | 1997-01-24 | Injection molding apparatus with cooled core |
Country Status (2)
| Country | Link |
|---|---|
| BR (1) | BR9800256A (en) |
| CA (1) | CA2195907A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004067257A1 (en) * | 2003-01-25 | 2004-08-12 | Husky Injection Molding Systems Ltd. | Core cooling tube assembly |
-
1997
- 1997-01-24 CA CA 2195907 patent/CA2195907A1/en not_active Abandoned
-
1998
- 1998-01-16 BR BR9800256A patent/BR9800256A/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004067257A1 (en) * | 2003-01-25 | 2004-08-12 | Husky Injection Molding Systems Ltd. | Core cooling tube assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| BR9800256A (en) | 1999-09-28 |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |