CA2082700A1 - Injection molding torpedo with diagonal melt bore - Google Patents
Injection molding torpedo with diagonal melt boreInfo
- Publication number
- CA2082700A1 CA2082700A1 CA 2082700 CA2082700A CA2082700A1 CA 2082700 A1 CA2082700 A1 CA 2082700A1 CA 2082700 CA2082700 CA 2082700 CA 2082700 A CA2082700 A CA 2082700A CA 2082700 A1 CA2082700 A1 CA 2082700A1
- Authority
- CA
- Canada
- Prior art keywords
- torpedo
- nozzle
- melt
- injection molding
- extending
- 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 22
- 239000000155 melt Substances 0.000 claims abstract description 44
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 2
- DMFGNRRURHSENX-UHFFFAOYSA-N beryllium copper Chemical compound [Be].[Cu] DMFGNRRURHSENX-UHFFFAOYSA-N 0.000 claims description 2
- 238000002347 injection Methods 0.000 abstract description 10
- 239000007924 injection Substances 0.000 abstract description 10
- 229910052751 metal Inorganic materials 0.000 abstract description 5
- 239000002184 metal Substances 0.000 abstract description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 230000000717 retained effect Effects 0.000 description 4
- 241000251729 Elasmobranchii Species 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000006903 response to temperature Effects 0.000 description 2
- 125000006850 spacer group Chemical group 0.000 description 2
- 206010013642 Drooling Diseases 0.000 description 1
- 108091092889 HOTTIP Proteins 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 208000008630 Sialorrhea Diseases 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000161 steel melt Substances 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
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/278—Nozzle tips
-
- 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
- B29C2045/2761—Seals between nozzle and mould or gate
-
- 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
- B29C2045/2783—Nozzle tips with a non-axial outlet opening of the melt channel
Abstract
ABSTRACT OF THE DISCLOSURE
An injection molding torpedo having a main portion and a forward portion with a conical surface having a forward tip. The main portion is received in a seat in the forward end of a nozzle with the forward tip aligned with the gate. The torpedo has a melt bore with a central rear portion and a diagonal portion extending to the conical surface. The main portion has an outer surface which fits in contact with the surrounding heated nozzle and the configuration of the melt bore provides the torpedo with a greater area of highly conductive metal. This allows the temperature in the tip to respond rapidly to thermal changes during the injection cycle so cycle time can be reduced.
An injection molding torpedo having a main portion and a forward portion with a conical surface having a forward tip. The main portion is received in a seat in the forward end of a nozzle with the forward tip aligned with the gate. The torpedo has a melt bore with a central rear portion and a diagonal portion extending to the conical surface. The main portion has an outer surface which fits in contact with the surrounding heated nozzle and the configuration of the melt bore provides the torpedo with a greater area of highly conductive metal. This allows the temperature in the tip to respond rapidly to thermal changes during the injection cycle so cycle time can be reduced.
Description
~0~327~)0 INJECTION MOLDING TORPEDO WITH
DIAGONAI- I~EIIT BORE
BACKGROUND OF THE INVENTION
This invention relates generally to injection molding and more particularly to a torpedo having a tip and a diagonally extending melt bore to be mounted at the forward end of an injection molding nozzle. ~
Seating a torpedo having a conical surface ~ ;
leading to a forward tip in a heated nozzle to control the -build up of excessive friction heat in the area of the gate is well known as one type of hot tip gating. The forward '~
end of the nozzle is separated from the cavity plate -~
through which the gate extends by an insulative air space ~ -which usually is bridged to prevent the melt escaping into the air space. In one previous type seen in the applicant's U.S. patent number 4,450,999 which issued May 29, 1984, the torpedo has a central shaft with a forward : ~
2Ct~7~)0 tip which is ronnected by a number of radial ribs to an outer collar which bridges the insulative air space. The melt flows through a number of channels extending between the ribs around the central shaft to the gate. In another previous type seen in the applicant's U.S. patent number 5,028,227 which issued July 2, 1991, the ribs extend inwardly from a mounting ring or flange which is secured in place by a gate insert which bridges the air space between the forward end of the nozzle and the cavity plate. A
similar arrangement is shown in the applicant's Canadian patent application serial number filed September 22, 1992 entitled "Injection Molding Nozzle with Thermocouple Receiving Torpedo", but in that case the outer collar is retained in place by a cylindrical nozzle seal and there is only a single rib extending in to the central shaft. All of these previous torpedoes have a central shaft held in place by one or more radial ribs. The metal ribs necessarily have a thin cross-section which restricts heat transfer through them. Also, the previous torpedoes having a ribbed configuration are relatively costly to manufacture. The applicant's U.S. patent number 4,583,284 which issued April 22, 1986 shows a nozzle having a tip and a melt bore having a diagonal portion, but there is no provision for a replaceable torpedo.
~c~ o 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 replaceable torpedo which is economical to make and has a tip with a rapid response to temperature changes.
To this end, in one of its aspects, the invention provides an injection molding torpedo to be mounted at the forward end of a nozzle, the nozzle having a melt passage with an inner surface and a predetermined diameter extending therethrough in alignment with a gate, the forward end of the nozzle having a seat with a forward facing shoulder and an inner surface extending around the melt passage to receive the torpedo, the torpedo comprising a main portion having a reax end, a forward portion extending from the main portion, and a melt bore extending therethrough, the main portion having a rearward facing surface to abut against the forward facing shoulder in the nozzle to seat the torpedo in the seat in the nozzle, the forward portion having a conical surface with a forward tip to extend centrally in alignment with the gate and provide a space around the conical surface leading to the gate, the melt bore extending from the rear end with a diagonal portion extending to the conical surface to convey melt from the melt passage in the nozzle to the space around the XG~271~)0 conical surface leading to the gate. ;
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
¦ BRIEF DESCRIPTION OF THE__RAWINGS
¦ Figure 1 is a sectional view of a portion of an injection molding system showing a torpedo according to a first preferred embodiment of the invention, Figure 2 is an exploded isometric view showing the torpedo and nozzle seal in position for insertion in the nozzle seen in Figure 1, Figure 3 is a sectional view showing the torpedo ¦ retained in position by a gate insert, and 1 15 Figure 4 is a sectional view showing a torpedo ¦ according to a second preferred embodiment of the invention.
¦ DETAILED DESCRIPTION OF_THE INVENTION
Reference is first made to Figures 1 and 2 which show a portion of a multi-cavity injection molding system ~ having several nozzles 10 to convey pressurized plastic 'I melt to respective gates 12 leading to different cavities 14 in the mold 16. The mold 16 includes a cavity plate 18 and a back plate 20 which is secured to the cavity plate 18 ZC~Z7~0 by screws 22. Other molding configurations may have a variety of other plates or parts, depending on the application. The mold 16 is cooled by pumping cooling water through cooling conduits 24 extending in the cavity plate 18 and the back plate 20. An electrically heated steel melt distribution manifold 26 is mounted between the cavity plate 18 and the back plate 20 by a central locating ring 28 and insulative and resilient spacer members 30.
The melt distribution manifold 26 has a cylindrical inlet portion 32 and is heated by an integral electrical heating element 34. An insulative air space 36 is provided between the heated manifold 26 and the surrounding cooled cavity plate 18 and back plate 20. A melt passage 38 having a common inlet 39 in the inlet portion 32 of the manifold 26 branches outwardly in the manifold 26 and extends through each nozzle 10 to the gates 12.
Each nozzle 10 has a forward end 40 and a rear end 42 which abuts against the melt distribution manifold 26. An electrical heating element 44 extends helically around the centrally extending melt passage 38 and has an external terminal 48 to which power leads 50 are connected.
The nozzle 10 is received in a well 52 in the cavity plate 18 and is located in this position by having a circular insulation flange 54 which is seated against a matching shoulder 56 in the well 52 in the cavity plate 18. The ~C~3Z7~)0 nozzle 10 has an enlarged portion 58 adjacent its forward end 40 with a bore 60 into which a thermocouple element 62 extends to monitor the operating temperature adjacent the forward end 40 of the nozzle lO. The central melt passage 38 which extends from the manifold 26 through each nozzle 10 is aligned with the gate 12 extending through the cavity plate 18 to the cavity 14. The central melt passage 38 through the nozzle 10 has an inner surface 64 with a predetermined diameter. The forward end 40 of the nozzle 10 has a seat 66 with a forward facing shoulder 68 and a cylindrical inner surface 70 in which a torpedo 72 according to the invention is mounted.
In this embodiment, each torpedo 72 has a main portion 74 with an outer surface 76 and a forward portion 78 with a conical surface 80 extending to a forward tip 82.
The outer surface 76 has a circular mounting flange 84 extending outwardly around it. The torpedo 72 is accurately seated in position with the forward tip 82 in alignment with the gate 12 by the mounting flange 84 being secured in the seat 66 by a hollow nozzle seal 86 which is seated against the cavity plate 18 to extend around the gate 12. The forward end 40 of the heated nozzle 10 is separated from the cooled cavity plate 18 by an insulative air space 88, and in this embodiment the nozzle seal 86 bridges the air space 88 to prevent pressurized melt XC~327~)0 leaking into it. The manifold 26, nozzles 10, torpedoes 72, and nozzle seals 86 are securely retained in this position against the melt injection pressure by force from the screws 22 which is applied to the manifold 26 through the spacer members 30.
The nozzle seal 86 has a circular removal flange 92 which extends outwardly into the air space 88 and is spaced from the forward end 40 of the nozzle 10 to provide for removal of the nozzle seal 86 by prying it out with a screwdriver or other similar tool. The circular mounting flange 84 has a rearward facing surface 94 which abuts against the forward facing shoulder 68 of the seat 66. The outer surface 76 of the main portion 74 of the torpedo 72 has a first cylindrical portion 96 which extends rearwardly from the circular mounting flange 84 to the rear end 98 and fits in contact with the inner surface 64 of the melt passage 38 through the nozzle 10. The outer surface 76 of the main portion 74 of the torpedo 72 also has a second cylindrical portion 100 which extends forwardly from the mounting flange 84 to the conical surface 80 and fits in . contact with the surrounding nozzle seal 86 which in turn fits in contact with the inner surface 70 of the seat 66.
Each torpedo 72 also has a melt bore 102 with a rear portion 104 which extends centrally from the rear end 98 and a diagonal portion 106 which extends from the rear ~: ' ::
~C~327~0 portion 104 to the conical surface 80. The rear portion 104 tapers inwardly from a diameter at the rear end 98 which is equal in diameter to and in alignment with the melt passage 38 through the nozzle 10 to avoid turbulence in the melt flow. The melt from the melt passage 38 flows through the melt boxe 102 in the torpedo into a space 108 around the conical surface 80 which leads to the gate 12.
The torpedo is made of a highly heat conductive metal such as a beryllium copper alloy or molybdenum. The configuration of the torpedo 72 and the extent of contact with the surrounding nozzle 10 and nozzle seal 86 provides the forward tip 82 with a rapid response to temperature changes during the injection cycle.
In use, the injection molding system is assembled as shown in Figure 1. While only a single cavity 14 has been shown for ease of illustration, it will be appreciated that the melt distribution manifold 26 normally has many more melt passage branches extending to numerous cavities 14 depending on the application. Electrical power is applied to the heating element 34 in the manifold 26 and to the heating elements 44 in the nozzles 10 to heat them to a predetermined operating temperature. Pressurized melt from a molding machine (not shown) is then injected into the melt passage 38 through the common inlet 39 according to a predetermined cycle in a conventional manner. The : `~
2C~;~7~)0 pressurized melt flows through each nozzle 10 and the melt bore 102 of the aligned torpedo 72 into the space 108 around the conical surface 80 and then through the aligned gate 12 to fill the respective cavity 14. After the cavities 14 are filled, injection pressure is held momentarily to pack and then released. After a short cooling period, the mold is opened to eject the molded products. After ejection, the mold is closed and injection pressure is reapplied to refill the cavities 14. This cycle is continuously repeated with a frequency dependent on the size and shape of the cavities 14 and the type of material being molded. For initial start-up of the molding process, heat from the heating element 44 in each nozzle 10 ¦ is conducted forwardly through the torpedo 72 to the tip 82 aligned with the gate 12. During injection, the torpedo 72 conducts excess heat which is generated by friction of the melt flowing through the constricted area of the gate 12 rearwardly to avoid stringing and drooling of the melt when the mold opens for ejection. After the melt has stopped flowing, solidification in the gate is enhanced by the removal of the excess friction heat through the torpedo 72.
In many applications, ambient heat in the melt from the machine cylinder and friction heat is sufficient to keep the system functioning after start-up. This heat prevents the melt completely freezing in the zrea of the gate 12 and .. .' ' . .
~C~Z7~)0 forming a solid plug which would interfere with injection when injection pressure is reapplied after the mold is closed. The configuration of the torpedo 72 according to the invention does not have restricted cross-sections of the conductive metal through which the heat must flow and there are large areas of contact between the torpedo 72 and the surrounding nozzle 10 and nozzle seal 86. This provides the forward tip 82 with a rapid response to these changes in temperature during the injection cycle and thus cycle time can be reduced.
Reference is now made to Figures 3 and 4 to describe other applications and embodiments of the invention. As many of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals. Referring first to Figure 3, the configuration of the torpedo 72 is the same as that described above, but it is secured in place in the seat 66 in the forward end 40 of the nozzle 10 by a hollow gate insert 110 rather than by a nozzle seal.
The gate insert 110 has a tapered forward portion 112 seated in a tapered opening 114 which extends through the cavity plate 18 to the cavity 14. The gate insert 110 has a cylindrical rear portion 116 which extends into the seat 66 in the forward end 40 of the nozzle 10 and fits in contact with the surrounding inner surface 70 of the seat.
DIAGONAI- I~EIIT BORE
BACKGROUND OF THE INVENTION
This invention relates generally to injection molding and more particularly to a torpedo having a tip and a diagonally extending melt bore to be mounted at the forward end of an injection molding nozzle. ~
Seating a torpedo having a conical surface ~ ;
leading to a forward tip in a heated nozzle to control the -build up of excessive friction heat in the area of the gate is well known as one type of hot tip gating. The forward '~
end of the nozzle is separated from the cavity plate -~
through which the gate extends by an insulative air space ~ -which usually is bridged to prevent the melt escaping into the air space. In one previous type seen in the applicant's U.S. patent number 4,450,999 which issued May 29, 1984, the torpedo has a central shaft with a forward : ~
2Ct~7~)0 tip which is ronnected by a number of radial ribs to an outer collar which bridges the insulative air space. The melt flows through a number of channels extending between the ribs around the central shaft to the gate. In another previous type seen in the applicant's U.S. patent number 5,028,227 which issued July 2, 1991, the ribs extend inwardly from a mounting ring or flange which is secured in place by a gate insert which bridges the air space between the forward end of the nozzle and the cavity plate. A
similar arrangement is shown in the applicant's Canadian patent application serial number filed September 22, 1992 entitled "Injection Molding Nozzle with Thermocouple Receiving Torpedo", but in that case the outer collar is retained in place by a cylindrical nozzle seal and there is only a single rib extending in to the central shaft. All of these previous torpedoes have a central shaft held in place by one or more radial ribs. The metal ribs necessarily have a thin cross-section which restricts heat transfer through them. Also, the previous torpedoes having a ribbed configuration are relatively costly to manufacture. The applicant's U.S. patent number 4,583,284 which issued April 22, 1986 shows a nozzle having a tip and a melt bore having a diagonal portion, but there is no provision for a replaceable torpedo.
~c~ o 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 replaceable torpedo which is economical to make and has a tip with a rapid response to temperature changes.
To this end, in one of its aspects, the invention provides an injection molding torpedo to be mounted at the forward end of a nozzle, the nozzle having a melt passage with an inner surface and a predetermined diameter extending therethrough in alignment with a gate, the forward end of the nozzle having a seat with a forward facing shoulder and an inner surface extending around the melt passage to receive the torpedo, the torpedo comprising a main portion having a reax end, a forward portion extending from the main portion, and a melt bore extending therethrough, the main portion having a rearward facing surface to abut against the forward facing shoulder in the nozzle to seat the torpedo in the seat in the nozzle, the forward portion having a conical surface with a forward tip to extend centrally in alignment with the gate and provide a space around the conical surface leading to the gate, the melt bore extending from the rear end with a diagonal portion extending to the conical surface to convey melt from the melt passage in the nozzle to the space around the XG~271~)0 conical surface leading to the gate. ;
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
¦ BRIEF DESCRIPTION OF THE__RAWINGS
¦ Figure 1 is a sectional view of a portion of an injection molding system showing a torpedo according to a first preferred embodiment of the invention, Figure 2 is an exploded isometric view showing the torpedo and nozzle seal in position for insertion in the nozzle seen in Figure 1, Figure 3 is a sectional view showing the torpedo ¦ retained in position by a gate insert, and 1 15 Figure 4 is a sectional view showing a torpedo ¦ according to a second preferred embodiment of the invention.
¦ DETAILED DESCRIPTION OF_THE INVENTION
Reference is first made to Figures 1 and 2 which show a portion of a multi-cavity injection molding system ~ having several nozzles 10 to convey pressurized plastic 'I melt to respective gates 12 leading to different cavities 14 in the mold 16. The mold 16 includes a cavity plate 18 and a back plate 20 which is secured to the cavity plate 18 ZC~Z7~0 by screws 22. Other molding configurations may have a variety of other plates or parts, depending on the application. The mold 16 is cooled by pumping cooling water through cooling conduits 24 extending in the cavity plate 18 and the back plate 20. An electrically heated steel melt distribution manifold 26 is mounted between the cavity plate 18 and the back plate 20 by a central locating ring 28 and insulative and resilient spacer members 30.
The melt distribution manifold 26 has a cylindrical inlet portion 32 and is heated by an integral electrical heating element 34. An insulative air space 36 is provided between the heated manifold 26 and the surrounding cooled cavity plate 18 and back plate 20. A melt passage 38 having a common inlet 39 in the inlet portion 32 of the manifold 26 branches outwardly in the manifold 26 and extends through each nozzle 10 to the gates 12.
Each nozzle 10 has a forward end 40 and a rear end 42 which abuts against the melt distribution manifold 26. An electrical heating element 44 extends helically around the centrally extending melt passage 38 and has an external terminal 48 to which power leads 50 are connected.
The nozzle 10 is received in a well 52 in the cavity plate 18 and is located in this position by having a circular insulation flange 54 which is seated against a matching shoulder 56 in the well 52 in the cavity plate 18. The ~C~3Z7~)0 nozzle 10 has an enlarged portion 58 adjacent its forward end 40 with a bore 60 into which a thermocouple element 62 extends to monitor the operating temperature adjacent the forward end 40 of the nozzle lO. The central melt passage 38 which extends from the manifold 26 through each nozzle 10 is aligned with the gate 12 extending through the cavity plate 18 to the cavity 14. The central melt passage 38 through the nozzle 10 has an inner surface 64 with a predetermined diameter. The forward end 40 of the nozzle 10 has a seat 66 with a forward facing shoulder 68 and a cylindrical inner surface 70 in which a torpedo 72 according to the invention is mounted.
In this embodiment, each torpedo 72 has a main portion 74 with an outer surface 76 and a forward portion 78 with a conical surface 80 extending to a forward tip 82.
The outer surface 76 has a circular mounting flange 84 extending outwardly around it. The torpedo 72 is accurately seated in position with the forward tip 82 in alignment with the gate 12 by the mounting flange 84 being secured in the seat 66 by a hollow nozzle seal 86 which is seated against the cavity plate 18 to extend around the gate 12. The forward end 40 of the heated nozzle 10 is separated from the cooled cavity plate 18 by an insulative air space 88, and in this embodiment the nozzle seal 86 bridges the air space 88 to prevent pressurized melt XC~327~)0 leaking into it. The manifold 26, nozzles 10, torpedoes 72, and nozzle seals 86 are securely retained in this position against the melt injection pressure by force from the screws 22 which is applied to the manifold 26 through the spacer members 30.
The nozzle seal 86 has a circular removal flange 92 which extends outwardly into the air space 88 and is spaced from the forward end 40 of the nozzle 10 to provide for removal of the nozzle seal 86 by prying it out with a screwdriver or other similar tool. The circular mounting flange 84 has a rearward facing surface 94 which abuts against the forward facing shoulder 68 of the seat 66. The outer surface 76 of the main portion 74 of the torpedo 72 has a first cylindrical portion 96 which extends rearwardly from the circular mounting flange 84 to the rear end 98 and fits in contact with the inner surface 64 of the melt passage 38 through the nozzle 10. The outer surface 76 of the main portion 74 of the torpedo 72 also has a second cylindrical portion 100 which extends forwardly from the mounting flange 84 to the conical surface 80 and fits in . contact with the surrounding nozzle seal 86 which in turn fits in contact with the inner surface 70 of the seat 66.
Each torpedo 72 also has a melt bore 102 with a rear portion 104 which extends centrally from the rear end 98 and a diagonal portion 106 which extends from the rear ~: ' ::
~C~327~0 portion 104 to the conical surface 80. The rear portion 104 tapers inwardly from a diameter at the rear end 98 which is equal in diameter to and in alignment with the melt passage 38 through the nozzle 10 to avoid turbulence in the melt flow. The melt from the melt passage 38 flows through the melt boxe 102 in the torpedo into a space 108 around the conical surface 80 which leads to the gate 12.
The torpedo is made of a highly heat conductive metal such as a beryllium copper alloy or molybdenum. The configuration of the torpedo 72 and the extent of contact with the surrounding nozzle 10 and nozzle seal 86 provides the forward tip 82 with a rapid response to temperature changes during the injection cycle.
In use, the injection molding system is assembled as shown in Figure 1. While only a single cavity 14 has been shown for ease of illustration, it will be appreciated that the melt distribution manifold 26 normally has many more melt passage branches extending to numerous cavities 14 depending on the application. Electrical power is applied to the heating element 34 in the manifold 26 and to the heating elements 44 in the nozzles 10 to heat them to a predetermined operating temperature. Pressurized melt from a molding machine (not shown) is then injected into the melt passage 38 through the common inlet 39 according to a predetermined cycle in a conventional manner. The : `~
2C~;~7~)0 pressurized melt flows through each nozzle 10 and the melt bore 102 of the aligned torpedo 72 into the space 108 around the conical surface 80 and then through the aligned gate 12 to fill the respective cavity 14. After the cavities 14 are filled, injection pressure is held momentarily to pack and then released. After a short cooling period, the mold is opened to eject the molded products. After ejection, the mold is closed and injection pressure is reapplied to refill the cavities 14. This cycle is continuously repeated with a frequency dependent on the size and shape of the cavities 14 and the type of material being molded. For initial start-up of the molding process, heat from the heating element 44 in each nozzle 10 ¦ is conducted forwardly through the torpedo 72 to the tip 82 aligned with the gate 12. During injection, the torpedo 72 conducts excess heat which is generated by friction of the melt flowing through the constricted area of the gate 12 rearwardly to avoid stringing and drooling of the melt when the mold opens for ejection. After the melt has stopped flowing, solidification in the gate is enhanced by the removal of the excess friction heat through the torpedo 72.
In many applications, ambient heat in the melt from the machine cylinder and friction heat is sufficient to keep the system functioning after start-up. This heat prevents the melt completely freezing in the zrea of the gate 12 and .. .' ' . .
~C~Z7~)0 forming a solid plug which would interfere with injection when injection pressure is reapplied after the mold is closed. The configuration of the torpedo 72 according to the invention does not have restricted cross-sections of the conductive metal through which the heat must flow and there are large areas of contact between the torpedo 72 and the surrounding nozzle 10 and nozzle seal 86. This provides the forward tip 82 with a rapid response to these changes in temperature during the injection cycle and thus cycle time can be reduced.
Reference is now made to Figures 3 and 4 to describe other applications and embodiments of the invention. As many of the elements are the same as those described above, common elements are described and illustrated using the same reference numerals. Referring first to Figure 3, the configuration of the torpedo 72 is the same as that described above, but it is secured in place in the seat 66 in the forward end 40 of the nozzle 10 by a hollow gate insert 110 rather than by a nozzle seal.
The gate insert 110 has a tapered forward portion 112 seated in a tapered opening 114 which extends through the cavity plate 18 to the cavity 14. The gate insert 110 has a cylindrical rear portion 116 which extends into the seat 66 in the forward end 40 of the nozzle 10 and fits in contact with the surrounding inner surface 70 of the seat.
2(:~3Z7~)0 The torpedo 72 is retained in place by the circular mounting flange 84 being secured between the forward facing shoulder 68 of the seat 66 and the rear portion 116 of the gate insert 110. The gate insert 110 bridges the air space 88 between the forward end 40 of the nozzle 10 and the cavity plate 18 and also has a circular removal flange 118.
The first cylindrical portion 96 of the outer surface 76 of the main portion 74 of the torpedo 72 fits in contact with the inner surface 64 of the melt passage 38 through the nozzle 10, and the second c,vlindrical portion 100 of the outer surface 76 fits in contact with the surrounding gate insert 110. Thus, in use, the tip 82 of the torpedo 72 will have the same rapid response to thermal requirements during the injection cycle described above.
Another embodiment of the invention is shown in Figure 4 in which the rear end 98 of the main portion 74 of the torpedo 72 abuts against the forward facing shoulder 68 of the seat 66. The first cylindrical portion 96 of the outer surface 76 which extends from the rear end 98 fits in contact with the inner surface 70 of the seat 66. The second cylindrical portion 100 is smaller in diameter than the first cylindrical portion 96 and extends forwardly from a shoulder 120 which extends inwardly from the first cylindrical portion 96. A nozzle seal 86 as described above abuts against this shoulder 120 and the second .
Z~i~3Z7~0 cylindrical portion 96 fits in contact with the surrounding nozzle seal 86. Of course, the melt bore 102 through the torpedo also has the central rear portion 104 and the diagonal portion 106 extending to the conical surface 80 which is relatively easy to machine and provides the torpedo 72 with a greater area of highly conductive metal for heat transfer to and from the forward tip 82 While the description of the torpedo 72 has been given with respect to preferred embodiments, it will be evident that various other modifications are possible without departing from the scope of the invention as understood by those skilled in the art and as defined in the following claims.
' ~i ''I
.~
.i
The first cylindrical portion 96 of the outer surface 76 of the main portion 74 of the torpedo 72 fits in contact with the inner surface 64 of the melt passage 38 through the nozzle 10, and the second c,vlindrical portion 100 of the outer surface 76 fits in contact with the surrounding gate insert 110. Thus, in use, the tip 82 of the torpedo 72 will have the same rapid response to thermal requirements during the injection cycle described above.
Another embodiment of the invention is shown in Figure 4 in which the rear end 98 of the main portion 74 of the torpedo 72 abuts against the forward facing shoulder 68 of the seat 66. The first cylindrical portion 96 of the outer surface 76 which extends from the rear end 98 fits in contact with the inner surface 70 of the seat 66. The second cylindrical portion 100 is smaller in diameter than the first cylindrical portion 96 and extends forwardly from a shoulder 120 which extends inwardly from the first cylindrical portion 96. A nozzle seal 86 as described above abuts against this shoulder 120 and the second .
Z~i~3Z7~0 cylindrical portion 96 fits in contact with the surrounding nozzle seal 86. Of course, the melt bore 102 through the torpedo also has the central rear portion 104 and the diagonal portion 106 extending to the conical surface 80 which is relatively easy to machine and provides the torpedo 72 with a greater area of highly conductive metal for heat transfer to and from the forward tip 82 While the description of the torpedo 72 has been given with respect to preferred embodiments, it will be evident that various other modifications are possible without departing from the scope of the invention as understood by those skilled in the art and as defined in the following claims.
' ~i ''I
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.i
Claims (12)
1. An injection molding torpedo to be mounted at the forward end of a nozzle, the nozzle having a melt passage with an inner surface and a predetermined diameter extending therethrough in alignment with a gate, the forward end of the nozzle having a seat with a forward facing shoulder and an inner surface extending around the melt passage to receive the torpedo, the torpedo comprising a main portion having a rear end, a forward portion extending from the main portion, and a melt bore extending therethrough, the main portion having a rearward facing surface to abut against the forward facing shoulder in the nozzle to seat the torpedo in the seat in the nozzle, the forward portion having a conical surface with a forward tip to extend centrally in alignment with the gate and provide a space around the conical surface leading to the gate, the melt bore extending from the rear end with a diagonal portion extending to the conical surface to convey melt from the melt passage in the nozzle to the space around the conical surface leading to the gate.
2. An injection molding torpedo as claimed in claim 1 wherein the melt bore has a rear portion which tapers inwardly from a rear diameter at the rear end of the main portion of the torpedo and extends centrally to the diagonal portion of the melt bore, the rear diameter of the rear portion of the melt bore being equal in diameter to and in alignment with the melt passage through the nozzle.
3. An injection molding torpedo as claimed in claim 2 wherein the torpedo is formed of a beryllium copper alloy.
4. An injection molding torpedo as claimed in claim 2 wherein the gate extends through a cavity plate and the forward end of the nozzle is separated from the cavity plate by an insulative air space, the main portion of the torpedo having an outer surface with a mounting flange extending outwardly from the outer surface to be secured in the seat in the forward end of the nozzle between the forward facing shoulder and a hollow nozzle seal seated around the gate between the forward end of the nozzle and the cavity plate to bridge the air space and prevent leakage of melt into the air space.
5. An injection molding torpedo as claimed in claim 4 wherein the outwardly extending mounting flange is circular.
6. An injection molding torpedo as claimed in claim 5 wherein the outer surface of the main portion of the torpedo has a first cylindrical portion extending rearwardly from the mounting flange into the melt passage in the nozzle to fit in contact with the inner surface of the melt passage.
7. An injection molding torpedo as claimed in claim 6 wherein the outer surface of the main portion of the torpedo has a second cylindrical portion extending forwardly from the mounting flange to fit in contact with the surrounding nozzle seal.
8. An injection molding torpedo as claimed in claim 2 wherein the gate extends through a hollow gate insert seated in a cavity plate, the gate insert having a rear portion extending into the seat in the forward end of the nozzle, the main portion of the torpedo having an outer surface with a mounting flange extending outwardly from the outer surface to be secured in the seat in the forward end of the nozzle between the forward facing shoulder and the rear portion of the gate insert.
9. An injection molding torpedo as claimed in claim 8 wherein the outwardly extending mounting flange is circular.
10. An injection molding torpedo as claimed in claim 9 wherein the outer surface of the main portion of the torpedo has a first cylindrical portion extending rearwardly from the mounting flange into the melt passage in the nozzle to fit in contact with the inner surface of the melt passage.
11. An injection molding torpedo as claimed in claim 10 wherein the outer surface of the main portion of the torpedo has a second cylindrical portion extending forwardly from the mounting flange to fit in contact with the surrounding gate insert.
12. An injection molding torpedo as claimed in claim 2 wherein the gate extends through a cavity plate and the forward end of the nozzle is separated from the cavity plate by an insulative air space, the torpedo being secured in the seat in the forward end of the nozzle with the rear end of the main portion of the torpedo abuting against the forward facing shoulder in the nozzle by a hollow nozzle seal seated around the gate to bridge the air space and prevent leakage of melt into the air space, the outer surface of the main portion of the torpedo having a first cylindrical portion and a second cylindrical portion, the first cylindrical portion extending forwardly from the rear end to an inwardly extending shoulder to fit in contact with the inner surface of the seat in the nozzle, the second cylindrical portion being smaller in diameter than the first cylindrical portion and extending forwardly from the inwardly extending shoulder to fit in contact with a surrounding nozzle seal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2082700 CA2082700A1 (en) | 1992-11-12 | 1992-11-12 | Injection molding torpedo with diagonal melt bore |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2082700 CA2082700A1 (en) | 1992-11-12 | 1992-11-12 | Injection molding torpedo with diagonal melt bore |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2082700A1 true CA2082700A1 (en) | 1994-05-13 |
Family
ID=4150681
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2082700 Abandoned CA2082700A1 (en) | 1992-11-12 | 1992-11-12 | Injection molding torpedo with diagonal melt bore |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2082700A1 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0780209A1 (en) * | 1995-12-18 | 1997-06-25 | Mold-Masters Limited | Injection molding carbide torpedo |
| EP0988137A1 (en) * | 1997-06-13 | 2000-03-29 | Incoe Corporation | Injection molding shut-off bushing with separate material flow path |
| WO2001028750A1 (en) * | 1999-10-18 | 2001-04-26 | Mold-Masters Limited | Injection nozzle system |
| WO2002040245A1 (en) * | 2000-11-20 | 2002-05-23 | Top Grade Molds Ltd. | Nozzle for injection mold |
| US7780434B2 (en) | 2001-10-03 | 2010-08-24 | Mold-Masters (2007) Limited | Nozzle for an injection molding apparatus |
| CN103386737A (en) * | 2012-05-08 | 2013-11-13 | 昆山夏福特五金电子科技有限公司 | Novel hot runner injection mould |
-
1992
- 1992-11-12 CA CA 2082700 patent/CA2082700A1/en not_active Abandoned
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0780209A1 (en) * | 1995-12-18 | 1997-06-25 | Mold-Masters Limited | Injection molding carbide torpedo |
| EP0988137A1 (en) * | 1997-06-13 | 2000-03-29 | Incoe Corporation | Injection molding shut-off bushing with separate material flow path |
| EP0988137A4 (en) * | 1997-06-13 | 2002-07-24 | Incoe Corp | Injection molding shut-off bushing with separate material flow path |
| WO2001028750A1 (en) * | 1999-10-18 | 2001-04-26 | Mold-Masters Limited | Injection nozzle system |
| US6789745B1 (en) | 1999-10-18 | 2004-09-14 | Mold-Masters Limited | Injection nozzle system |
| US7201335B2 (en) | 1999-10-18 | 2007-04-10 | Mold-Masters Limited | Injection nozzle system |
| WO2002040245A1 (en) * | 2000-11-20 | 2002-05-23 | Top Grade Molds Ltd. | Nozzle for injection mold |
| US6971868B2 (en) | 2000-11-20 | 2005-12-06 | Injectnotech Inc. | Nozzle for injection mold |
| US7780434B2 (en) | 2001-10-03 | 2010-08-24 | Mold-Masters (2007) Limited | Nozzle for an injection molding apparatus |
| US7891969B2 (en) | 2001-10-03 | 2011-02-22 | Mold-Masters (2007) Limited | Injection molding nozzle |
| CN103386737A (en) * | 2012-05-08 | 2013-11-13 | 昆山夏福特五金电子科技有限公司 | Novel hot runner injection mould |
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