CA2010381A1 - Valve gated sequential injection molding apparatus - Google Patents
Valve gated sequential injection molding apparatusInfo
- Publication number
- CA2010381A1 CA2010381A1 CA 2010381 CA2010381A CA2010381A1 CA 2010381 A1 CA2010381 A1 CA 2010381A1 CA 2010381 CA2010381 CA 2010381 CA 2010381 A CA2010381 A CA 2010381A CA 2010381 A1 CA2010381 A1 CA 2010381A1
- Authority
- CA
- Canada
- Prior art keywords
- valve member
- nozzle
- central bore
- gate
- cavity
- 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 description 12
- 239000012530 fluid Substances 0.000 claims abstract description 24
- 238000007789 sealing Methods 0.000 claims description 11
- 230000006872 improvement Effects 0.000 claims description 2
- 238000000465 moulding Methods 0.000 abstract description 17
- 230000007246 mechanism Effects 0.000 abstract description 12
- 239000000155 melt Substances 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 4
- 239000004033 plastic Substances 0.000 abstract description 3
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 239000003086 colorant Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 201000009240 nasopharyngitis Diseases 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000126 substance 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
- B29C45/16—Making multilayered or multicoloured articles
- B29C45/1603—Multi-way nozzles specially adapted therefor
- B29C45/1606—Multi-way nozzles specially adapted therefor using a rotatable valve
-
- 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
- B29C45/28—Closure devices therefor
- B29C45/2806—Closure devices therefor consisting of needle valve systems
- B29C45/281—Drive means therefor
- B29C2045/2837—Needle valves driven by rack and pinion
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Valve gated hot runner molding system or apparatus for sequentially injecting different types of fluid or plastic melt into a cavity. A valve member is reciprocated between forward closed and retracted open positions in a central bore in a heated nozzle. Separate channels convey the different types of melt from different molding machines to angularly spaced outlets to the central bore near the forward end of the nozzle. The valve member is rotated by rack and pinion mechanism between corresponding angular positions. The valve member has a longitudinal groove near the forward end which connects one of the melt channel outlets to a larger diameter bore adjacent the gate when the valve member is retracted to the open position. After the first type of material partially fills the cavity around the outside, the valve member is rotated to fill the middle of the cavity with another type of material. The different channels join adjacent where the valve member closes the gate so there is no residual material from the wrong channel after each shot.
Valve gated hot runner molding system or apparatus for sequentially injecting different types of fluid or plastic melt into a cavity. A valve member is reciprocated between forward closed and retracted open positions in a central bore in a heated nozzle. Separate channels convey the different types of melt from different molding machines to angularly spaced outlets to the central bore near the forward end of the nozzle. The valve member is rotated by rack and pinion mechanism between corresponding angular positions. The valve member has a longitudinal groove near the forward end which connects one of the melt channel outlets to a larger diameter bore adjacent the gate when the valve member is retracted to the open position. After the first type of material partially fills the cavity around the outside, the valve member is rotated to fill the middle of the cavity with another type of material. The different channels join adjacent where the valve member closes the gate so there is no residual material from the wrong channel after each shot.
Description
VALVE GATED SEQUENTIAL
INJ~CTION ~OLDING APPARATVS
BACKGROUND OF THE INVENTION
1 This invention relates generally to injection molding and more specifically to an improved valve gated hot runner system or apparatus for sequentially injecting different types of fluid from different molding machines.
It is known in the injection molding field that it is desirable for some applications to sequentially inject different types of melt into a cavity. The different types of melt may have different chemical properties, may be of different colours, and/or may be of different qualities. In thick wall molding this is sometimes referred to as "sandwich moldingl', and may be used, for instance, to provide a relatively inexpensive filler inside a more durable outer coating. This is 3~3~
1 currently in sequence to a common injection molding machine which then supplies the pressurized melt to an open sprue which extends through the mold to the cavity or cavities. In thin wall molding this is sometimes referred to as "barrier molding~', and may be used, for instance, to provide a moisture barrier in a packaging material. This is currently done by sequentially feeding the melt from different molding machines, to melt channels which join outside the mold to a common cold sprue which extends through the mold to the cavity. This has the disadvantage that the molded product has an undesirable sprue stringing from it. The fact that the melt channels from the different molding machines join at a considerable distance from the cavity unavoidably extends cycle time.
Furthermore, the sprue extending to the gate is filled with the wrong type of material at the end of each cycle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome the problems of the prior art by providing valve gated apparatus wherein the different fluid channel which provide sequential fluid flow join adjacent the gate leading to each cavity.
To this end, in one of its aspects, the invention provides a valve gated hot runner injection 1 molding apparatus having at least one heated noæzle with a rear end and a forward end which is seated in a cavity plate, the nozzle having a central bore extending therethrough, an elongated valve member extending through the central bore of the nozzle in alignment with a gate extending to a cavity, the valve member having a rear end and a forward end, and valve member actuating means to reciprocate the valve member longitudinally between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the central bore through the nozzle having a sealing portion extending from the rear end of the nozzle to a forward portion adjacent the forward end of the nozzle, the rear portion having a diameter to snugly receive the valve member therein to prevent substantial melt seepage .
therebetween as the valve member reciprocates, the forward portion of the central bore being substantially larger in diameter than the sealing portion and extending to the gate, the improvement wherein at least first and second separate fluid channels extend from respective separate fluid sources through the nozzle to join the sealing portion of the central bore at an angularly spaced outlets near the forward portion of the central bore, the valve member has a longitudinally extending groove which is located near the forward end and is of sufficient length 3~ ~
1 to connect either of the outlets from the fluid channels to the forward portion of the central bore through the nozzle when the valve member is in the retracted open position, and means to rotate the valve member according to a predetermined cycle between a first angular position wherein the longitudinal groove connects the ~irst fluid channel to the forward portion of the central bore and a second angular position wherein the longitudinal groove connects the second fluid channel to the forward portion of the central bore, whereby fluid flows sequentially through the gate into the cavity, first from the first fluid channel and then from the second fluid channel.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an illustrative sectional view of a two cavity valve gated injection molding system or apparatus according to one embodiment of the invention;
Figure 2 is an illustrative cut-away isometric view of a portion of the system shown in Figure l; and Figure 3 is a larger sectional view showing the melt flow through the gate to one of the cavities seen in Figure 1.
X q ~ j1 r~
DETAILED DESCRIPTION OF THE DRAWINGS
1 Reference is first made to Figure 1 which shows a valve gated injection molding system or apparatus having a pair of heated steel nozzles 10, each of which is seated in a well 12 in a cooled cavity plate 14. As more clearly seen in Figure 2, each nozzle 10 is securely fastened by screws 16 in a desired position along the side surface 18 of an elongated heated steel manifold 20. In this embodiment, the manifold 20 is heated by an electric heating element 22 which is integrally cast into it as lO described in Gellert's U.S. patent number 4,688,622 which issued August 25, 1987. Each nozzle 10 is heated by a tubular heating element (not shown) as described in Schmidt et al. U.S. patent number 4,793,795 which issued December 27, 1988. The cavity plate 14 is cooled by 15 pumping cooling water through cooling conduits 26. The manifold 20 is position and located by a locating ring 28 seated between it and the cavity plate 14 to provide an insulative air space 30 between the heated manifold 20 and the cooled cavity plate 14. Similar insulative air spaces 20 32 are provided between each of the heated nozzles 10 and the surrounding cooled cavity plate 14. A manifold extension 34 fixed to the manifold 20 is located relative to the back plate 36 by another locating ring 38. For the 1 sake of clarity, the mold is shown having only a single cavity plate 14 and a back plate 36. However, as is well known in the art, the mold can have a number of other and/or different plates and components, depending on the size of the mold and the particular application.
Each nozzle 10 has a central valve member bore 40 extending therethrough from the rear end 42 to the forward end 44. The valve member bore 40 oE each nozzle 10 extends in alignment with a gate 46 leading to a cavity 48 having a desired shape. An elongated valve member 50 having a rear end 52 and a forward end 54 is received in the central bore 40 of each nozzle. The central bore 40 has a sealing portion 56 which extends from the rear end 42 of the nozzle 10 and has a diameter just large enough to snugly receive the valve member 50 therein to prevent substantial seepage of melt therebetween as the valve member 50 reciprocates.
As shown clearly in Figure 3, in this embodiment, each nozzle 10 includes a nozzle seal 58 which is screwed tightly into a seat 59 in the forward end 44 of the nozzle 10. Various types of nozzle seals 58 can be used and/ in other embodiments, gate inserts can be used such as shown in the applicant's Canadian patent application serial number 578,974 which was filed September 30, 1988 entitled "Injection Molding Nozzle with , 1 Replaceable Gate Insert'l. Each nozzle seal 58 also has a central bore 60 leading to the gate 46 e~tending through the cavity plate 14. In this embodiment, each nozzle seal has a forward end with a flange portion 62 which extends around a circumferential depression 64 having a predetermined shape. In use, the flange portion 62 abuts against the surface 66 of the cavity plate 14 to provide a seal, and the depression fills with melt which insulates against excessive thermal transfer to the cavity plate 14 around the gate 46. In addition to having a sealing portion 56, the central bore 40 of each nozzle 10 has a forward portion 68 adjacent the forward end 44 of the nozzle 10 which is substantially larger in diameter than the sealing portion 56. As clearly shown in Figure 3, part of the larger diameter forward portion 68 of the central bore 40 is formed by the nozzle seal. In this embodiment, the forward portion 68 has an outer surface 70 which tapers gradually outward from the sealing portion 56 and then tapers back inwardly in alignment with the gate 46.
Each valve member 50 extends rearwardly a considerable distance from the rear end 42 of the nozzle 10 and has a head 72 which is engaged by valve member actuating mechanism 74 seated in the mold to reciprocate the valve member 50 between a retracted open position and .. , :'''' ' ~, ' ' ,: . . , 1 a forward closed position in which the tapered forward end 54 is seated in the gate 46. In this embodiment, the actuating mechanisms 74 includes a piston 76 which reciprocates in a cylinder 78. The valve member 50 extends through the piston 76 and the enlarged head 72 is secured to it by a cap 80 as described in Butcher's U.S.
patent number 4,698,013 which issued October 6, 1987. The piston 76 has an elongated neck portion 82 which protrudes out through a V-shaped high pressure seal 84 which is seated in the cylinder 78 to prevent leakage of pressurized hydraulic fluid. The actuating mechanisms 74 are driven in unison according to a predetermined cycle by pressurized hydraulic fluid through lines 86,88. While hydraulic actuating mechanism is shown in this embodiment, pneumatic actuating mechanism can also be used to reciprocate the valve members 50.
Each valve member 50 also has a pinion 90 secured to it with outwardly extending teeth 92. The aligned teeth 92 on each valve member 50 are engaged by the teeth 94 on a rack 96 which is reciprocated according to the predetermined cycle by a pneumatically actuated piston 98 in a cylinder 100 which is seated in the cavity plate 14. In this embodiment, the outer end 102 of the rack 96 is slidably received in a slot 104 in the cavity plate 14, although a variety of other rack and pinion or 1 lever apparatus can be used to rotate the valve members 50 between different predetermined angular positions.
While there can be more in other embodiments, in this embodiment the manifold 20 and the manifold extension 34 have two separate melt channels 106,108 to receive different types of pressurized melt from separate molding machines 110,112. As clearly shown in Figure 2, these separate melt channels 106,108 extend forwardly through each nozzle 10 to join the sealing portion 56 of the central bore 40 at angularly spaced outlets 114,116 near the forward portion 68 of the bore 40. In this embodiment, the outlets 114,116 are opposite each other, but they can have other angular positions, particularly if these are more than two melt channels.
The valve members 50 each have a groove 118 which extends longitudinally near the forward end 54.
While this groove 118 is relatively short, it is of sufficient length to connect the outlets 114,116 of the melt channels 106,108 one at a time to the larger diameter forward portion 68 of the bore 40 when the valve member 50 is in the retracted open position. Melt then flows from that channel through the gate 46 into the cavity 48 until either the valve member 50 is rotated to another angular position or the valve member 50 is driven forwardly to the closed position.
-, 1 o ~ 3~
1 In use, the system or apparatus is assembled as shown and electric a power is applied to the heating elements to heat the nozzles 10 and the manifold 20 to a predetermined operating temperature. ~ydraulic pressure to the actuating mechanisms 74 and pneumatic pressure to the cylinder 100 are controlled according to a predetermined operating cycle by conventional valves and timing circuitry which is not shown. Different types of hot pressurized plastic melt is then injected into the two melt channels 106,108 by the molding machines 110,112 according to the operating cycle. The two types of melt may be desirable because they have different properties, different colours, and/or different costs. When hydraulic pressure is applied to the actuating mechanisms 74 to withdraw each valve member 50 to the open position, and each valve member 50 is rotated by the rack and pinion mechanism to a first angular position where the groove 118 is aligned with the Eirst melt channel 106, a first type 120 of pressurize melt flows from the first molding machine 110 through the first channel 106 into each cavity 4B. After a brief injection period, each valve member 50 is rotated by the rack and pinion mechanism to the second angular position shown in Figure 3 in which the groove 118 is aligned with the second melt channel 108. Injection pressure is then released by the first molding machine 110 , - : : . . ;
1 and applied by the second molding machine 112 so a second type 122 of pressurized melt flows from the second molding machine 112 through the second channel 108 into each cavity 48. As shown, this forces the first type 120 of melt along the outside of the cavity 48, and the inside fills with the second type 122 of melt. It will be appreciated that more melt layers can be provided by having more molding machines, melt channels and corresponding angular positions of the valve member 50.
When the cavities are full, injection pressure is held momentarily by the second molding machine 112 to pack.
The hydraulic pressure to the actuating mechanisms 74 is then reversed to drive the valve members 50 forward to the closed position in which the forward end 54 of one of the valve members 50 is seated in each of the gates 46. The injection pressure is then released and, after a short cooling period , the mold is opened for ejection. After ejection, the mold is closed, the rack and pinion mechanism rotates the valve members 50 back to the first angular position, hydraulic pressure is applied to retract the valve members 50 to the open position, and the cycle is repeated. As shown in Figure 2, the width of the teeth 92,94 of the rack 96 and pinion 90 must be sufficient that they remain engaged throughout the travel between the retracted open and forward cIosed positions of the valve member 50.
- . : .
. ~ . . . . ~
3$~
1 While the description of the injection molding system according to the invention has been given with respect to one embodiment, it is not to be construed in a limiting sense. Variations ancl modifications will occur to those skilled in the art. For instance, while a two cavity system is shown, it can apply to a single cavity system or to a system having a greater number of cavities. Also, while the description of the use of the system is made with reference to different types of plastic melt, the system can be used to mold a variety of different fluids including gases, liquid glycerine, Reference is made to the appended claims for a definition of the invention.
,
INJ~CTION ~OLDING APPARATVS
BACKGROUND OF THE INVENTION
1 This invention relates generally to injection molding and more specifically to an improved valve gated hot runner system or apparatus for sequentially injecting different types of fluid from different molding machines.
It is known in the injection molding field that it is desirable for some applications to sequentially inject different types of melt into a cavity. The different types of melt may have different chemical properties, may be of different colours, and/or may be of different qualities. In thick wall molding this is sometimes referred to as "sandwich moldingl', and may be used, for instance, to provide a relatively inexpensive filler inside a more durable outer coating. This is 3~3~
1 currently in sequence to a common injection molding machine which then supplies the pressurized melt to an open sprue which extends through the mold to the cavity or cavities. In thin wall molding this is sometimes referred to as "barrier molding~', and may be used, for instance, to provide a moisture barrier in a packaging material. This is currently done by sequentially feeding the melt from different molding machines, to melt channels which join outside the mold to a common cold sprue which extends through the mold to the cavity. This has the disadvantage that the molded product has an undesirable sprue stringing from it. The fact that the melt channels from the different molding machines join at a considerable distance from the cavity unavoidably extends cycle time.
Furthermore, the sprue extending to the gate is filled with the wrong type of material at the end of each cycle.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome the problems of the prior art by providing valve gated apparatus wherein the different fluid channel which provide sequential fluid flow join adjacent the gate leading to each cavity.
To this end, in one of its aspects, the invention provides a valve gated hot runner injection 1 molding apparatus having at least one heated noæzle with a rear end and a forward end which is seated in a cavity plate, the nozzle having a central bore extending therethrough, an elongated valve member extending through the central bore of the nozzle in alignment with a gate extending to a cavity, the valve member having a rear end and a forward end, and valve member actuating means to reciprocate the valve member longitudinally between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the central bore through the nozzle having a sealing portion extending from the rear end of the nozzle to a forward portion adjacent the forward end of the nozzle, the rear portion having a diameter to snugly receive the valve member therein to prevent substantial melt seepage .
therebetween as the valve member reciprocates, the forward portion of the central bore being substantially larger in diameter than the sealing portion and extending to the gate, the improvement wherein at least first and second separate fluid channels extend from respective separate fluid sources through the nozzle to join the sealing portion of the central bore at an angularly spaced outlets near the forward portion of the central bore, the valve member has a longitudinally extending groove which is located near the forward end and is of sufficient length 3~ ~
1 to connect either of the outlets from the fluid channels to the forward portion of the central bore through the nozzle when the valve member is in the retracted open position, and means to rotate the valve member according to a predetermined cycle between a first angular position wherein the longitudinal groove connects the ~irst fluid channel to the forward portion of the central bore and a second angular position wherein the longitudinal groove connects the second fluid channel to the forward portion of the central bore, whereby fluid flows sequentially through the gate into the cavity, first from the first fluid channel and then from the second fluid channel.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an illustrative sectional view of a two cavity valve gated injection molding system or apparatus according to one embodiment of the invention;
Figure 2 is an illustrative cut-away isometric view of a portion of the system shown in Figure l; and Figure 3 is a larger sectional view showing the melt flow through the gate to one of the cavities seen in Figure 1.
X q ~ j1 r~
DETAILED DESCRIPTION OF THE DRAWINGS
1 Reference is first made to Figure 1 which shows a valve gated injection molding system or apparatus having a pair of heated steel nozzles 10, each of which is seated in a well 12 in a cooled cavity plate 14. As more clearly seen in Figure 2, each nozzle 10 is securely fastened by screws 16 in a desired position along the side surface 18 of an elongated heated steel manifold 20. In this embodiment, the manifold 20 is heated by an electric heating element 22 which is integrally cast into it as lO described in Gellert's U.S. patent number 4,688,622 which issued August 25, 1987. Each nozzle 10 is heated by a tubular heating element (not shown) as described in Schmidt et al. U.S. patent number 4,793,795 which issued December 27, 1988. The cavity plate 14 is cooled by 15 pumping cooling water through cooling conduits 26. The manifold 20 is position and located by a locating ring 28 seated between it and the cavity plate 14 to provide an insulative air space 30 between the heated manifold 20 and the cooled cavity plate 14. Similar insulative air spaces 20 32 are provided between each of the heated nozzles 10 and the surrounding cooled cavity plate 14. A manifold extension 34 fixed to the manifold 20 is located relative to the back plate 36 by another locating ring 38. For the 1 sake of clarity, the mold is shown having only a single cavity plate 14 and a back plate 36. However, as is well known in the art, the mold can have a number of other and/or different plates and components, depending on the size of the mold and the particular application.
Each nozzle 10 has a central valve member bore 40 extending therethrough from the rear end 42 to the forward end 44. The valve member bore 40 oE each nozzle 10 extends in alignment with a gate 46 leading to a cavity 48 having a desired shape. An elongated valve member 50 having a rear end 52 and a forward end 54 is received in the central bore 40 of each nozzle. The central bore 40 has a sealing portion 56 which extends from the rear end 42 of the nozzle 10 and has a diameter just large enough to snugly receive the valve member 50 therein to prevent substantial seepage of melt therebetween as the valve member 50 reciprocates.
As shown clearly in Figure 3, in this embodiment, each nozzle 10 includes a nozzle seal 58 which is screwed tightly into a seat 59 in the forward end 44 of the nozzle 10. Various types of nozzle seals 58 can be used and/ in other embodiments, gate inserts can be used such as shown in the applicant's Canadian patent application serial number 578,974 which was filed September 30, 1988 entitled "Injection Molding Nozzle with , 1 Replaceable Gate Insert'l. Each nozzle seal 58 also has a central bore 60 leading to the gate 46 e~tending through the cavity plate 14. In this embodiment, each nozzle seal has a forward end with a flange portion 62 which extends around a circumferential depression 64 having a predetermined shape. In use, the flange portion 62 abuts against the surface 66 of the cavity plate 14 to provide a seal, and the depression fills with melt which insulates against excessive thermal transfer to the cavity plate 14 around the gate 46. In addition to having a sealing portion 56, the central bore 40 of each nozzle 10 has a forward portion 68 adjacent the forward end 44 of the nozzle 10 which is substantially larger in diameter than the sealing portion 56. As clearly shown in Figure 3, part of the larger diameter forward portion 68 of the central bore 40 is formed by the nozzle seal. In this embodiment, the forward portion 68 has an outer surface 70 which tapers gradually outward from the sealing portion 56 and then tapers back inwardly in alignment with the gate 46.
Each valve member 50 extends rearwardly a considerable distance from the rear end 42 of the nozzle 10 and has a head 72 which is engaged by valve member actuating mechanism 74 seated in the mold to reciprocate the valve member 50 between a retracted open position and .. , :'''' ' ~, ' ' ,: . . , 1 a forward closed position in which the tapered forward end 54 is seated in the gate 46. In this embodiment, the actuating mechanisms 74 includes a piston 76 which reciprocates in a cylinder 78. The valve member 50 extends through the piston 76 and the enlarged head 72 is secured to it by a cap 80 as described in Butcher's U.S.
patent number 4,698,013 which issued October 6, 1987. The piston 76 has an elongated neck portion 82 which protrudes out through a V-shaped high pressure seal 84 which is seated in the cylinder 78 to prevent leakage of pressurized hydraulic fluid. The actuating mechanisms 74 are driven in unison according to a predetermined cycle by pressurized hydraulic fluid through lines 86,88. While hydraulic actuating mechanism is shown in this embodiment, pneumatic actuating mechanism can also be used to reciprocate the valve members 50.
Each valve member 50 also has a pinion 90 secured to it with outwardly extending teeth 92. The aligned teeth 92 on each valve member 50 are engaged by the teeth 94 on a rack 96 which is reciprocated according to the predetermined cycle by a pneumatically actuated piston 98 in a cylinder 100 which is seated in the cavity plate 14. In this embodiment, the outer end 102 of the rack 96 is slidably received in a slot 104 in the cavity plate 14, although a variety of other rack and pinion or 1 lever apparatus can be used to rotate the valve members 50 between different predetermined angular positions.
While there can be more in other embodiments, in this embodiment the manifold 20 and the manifold extension 34 have two separate melt channels 106,108 to receive different types of pressurized melt from separate molding machines 110,112. As clearly shown in Figure 2, these separate melt channels 106,108 extend forwardly through each nozzle 10 to join the sealing portion 56 of the central bore 40 at angularly spaced outlets 114,116 near the forward portion 68 of the bore 40. In this embodiment, the outlets 114,116 are opposite each other, but they can have other angular positions, particularly if these are more than two melt channels.
The valve members 50 each have a groove 118 which extends longitudinally near the forward end 54.
While this groove 118 is relatively short, it is of sufficient length to connect the outlets 114,116 of the melt channels 106,108 one at a time to the larger diameter forward portion 68 of the bore 40 when the valve member 50 is in the retracted open position. Melt then flows from that channel through the gate 46 into the cavity 48 until either the valve member 50 is rotated to another angular position or the valve member 50 is driven forwardly to the closed position.
-, 1 o ~ 3~
1 In use, the system or apparatus is assembled as shown and electric a power is applied to the heating elements to heat the nozzles 10 and the manifold 20 to a predetermined operating temperature. ~ydraulic pressure to the actuating mechanisms 74 and pneumatic pressure to the cylinder 100 are controlled according to a predetermined operating cycle by conventional valves and timing circuitry which is not shown. Different types of hot pressurized plastic melt is then injected into the two melt channels 106,108 by the molding machines 110,112 according to the operating cycle. The two types of melt may be desirable because they have different properties, different colours, and/or different costs. When hydraulic pressure is applied to the actuating mechanisms 74 to withdraw each valve member 50 to the open position, and each valve member 50 is rotated by the rack and pinion mechanism to a first angular position where the groove 118 is aligned with the Eirst melt channel 106, a first type 120 of pressurize melt flows from the first molding machine 110 through the first channel 106 into each cavity 4B. After a brief injection period, each valve member 50 is rotated by the rack and pinion mechanism to the second angular position shown in Figure 3 in which the groove 118 is aligned with the second melt channel 108. Injection pressure is then released by the first molding machine 110 , - : : . . ;
1 and applied by the second molding machine 112 so a second type 122 of pressurized melt flows from the second molding machine 112 through the second channel 108 into each cavity 48. As shown, this forces the first type 120 of melt along the outside of the cavity 48, and the inside fills with the second type 122 of melt. It will be appreciated that more melt layers can be provided by having more molding machines, melt channels and corresponding angular positions of the valve member 50.
When the cavities are full, injection pressure is held momentarily by the second molding machine 112 to pack.
The hydraulic pressure to the actuating mechanisms 74 is then reversed to drive the valve members 50 forward to the closed position in which the forward end 54 of one of the valve members 50 is seated in each of the gates 46. The injection pressure is then released and, after a short cooling period , the mold is opened for ejection. After ejection, the mold is closed, the rack and pinion mechanism rotates the valve members 50 back to the first angular position, hydraulic pressure is applied to retract the valve members 50 to the open position, and the cycle is repeated. As shown in Figure 2, the width of the teeth 92,94 of the rack 96 and pinion 90 must be sufficient that they remain engaged throughout the travel between the retracted open and forward cIosed positions of the valve member 50.
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. ~ . . . . ~
3$~
1 While the description of the injection molding system according to the invention has been given with respect to one embodiment, it is not to be construed in a limiting sense. Variations ancl modifications will occur to those skilled in the art. For instance, while a two cavity system is shown, it can apply to a single cavity system or to a system having a greater number of cavities. Also, while the description of the use of the system is made with reference to different types of plastic melt, the system can be used to mold a variety of different fluids including gases, liquid glycerine, Reference is made to the appended claims for a definition of the invention.
,
Claims (4)
1. In a valve gated hot runner injection molding apparatus having at least one heated nozzle with a rear end and a forward end which is seated in a cavity plate, the nozzle having a central bore extending therethrough, an elongated valve member extending through the central bore of the nozzle in alignment with a gate extending to a cavity, the valve member having a rear end and a forward end, and valve member actuating means to reciprocated the valve member longitudinally between a retracted open position and a forward closed position in which the forward end of the valve member is seated in the gate, the central bore through the nozzle having a sealing portion extending from the rear end of the nozzle to a forward portion adjacent the forward end of the nozzle, the rear portion having a diameter to snugly receive the valve member therein to prevent substantial melt seepage therebetween as the valve member reciprocates, the forward portion of the central; bore being substantially larger in diameter than the sealing portion and extending to the gate, the improvement wherein;
(a) at least first and second separate fluid channels extend from respective separate fluid sources through the nozzle to join the sealing portion of the central bore at an angularly spaced outlets near the forward portion of the central bore, (b) the valve member has a longitudianlly extending groove which is located near the forward end and is of sufficient length to connect either of the outlets from the fluid channels to the forward portion of the central bore through the nozzle when the valve member is in the retracted open position, and (c) means to rotate the valve member according to a predetermined cycle between a first angular position wherein the longitudinal groove connects the first fluid channel to the forward portion of the central bore and a second angular position wherein the longitudinal groove connects the second fluid channel to the forward portion of the central bore, whereby fluid flows sequentially through the gate into the cavity, first from the first fluid channel and then from the second fluid channel.
(a) at least first and second separate fluid channels extend from respective separate fluid sources through the nozzle to join the sealing portion of the central bore at an angularly spaced outlets near the forward portion of the central bore, (b) the valve member has a longitudianlly extending groove which is located near the forward end and is of sufficient length to connect either of the outlets from the fluid channels to the forward portion of the central bore through the nozzle when the valve member is in the retracted open position, and (c) means to rotate the valve member according to a predetermined cycle between a first angular position wherein the longitudinal groove connects the first fluid channel to the forward portion of the central bore and a second angular position wherein the longitudinal groove connects the second fluid channel to the forward portion of the central bore, whereby fluid flows sequentially through the gate into the cavity, first from the first fluid channel and then from the second fluid channel.
2. Injection molding apparatus as claimed in claim 1 wherein the at least first and second separate fluid channels are melt channels through which different types of melt flow sequentially into the cavity.
3. Injection molding apparatus as claimed in claim 2 wherein the nozzle includes a nozzle seal seated at the forward end of the nozzle, the nozzle seal having a central bore which extends from the gate and forms at least part of the larger diameter forward portion of the central bore of the nozzle.
4. Injection molding apparatus as claimed in claim 2 wherein the means to rotate the valve member includes teeth extending outwardly from the valve member, a longitudinally slidable rack member having a toothed portion which engages the teeth on the valve member, and drive means to reciprocate the rack member and thereby rotate the valve member between said first and second angular positions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2010381 CA2010381A1 (en) | 1990-02-19 | 1990-02-19 | Valve gated sequential injection molding apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2010381 CA2010381A1 (en) | 1990-02-19 | 1990-02-19 | Valve gated sequential injection molding apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2010381A1 true CA2010381A1 (en) | 1991-08-19 |
Family
ID=4144330
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2010381 Abandoned CA2010381A1 (en) | 1990-02-19 | 1990-02-19 | Valve gated sequential injection molding apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2010381A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999052699A1 (en) * | 1998-04-08 | 1999-10-21 | Johnson Control S.P.A. | Injector for co-injection |
| EP0790116A3 (en) * | 1996-02-19 | 1999-11-24 | Fried. Krupp AG Hoesch-Krupp | Method for injection moulding three-layered moulded objects and apparatus for carrying out the method |
| WO2022040787A1 (en) * | 2020-08-24 | 2022-03-03 | Mold-Masters (2007) Limited | Injection molding apparatus having a valve pin decouplable from a valve pin plate |
| CN114872279A (en) * | 2022-04-27 | 2022-08-09 | 欧唐科技（深圳）有限公司 | Internal and external tooth demoulding device for plastic mould product |
-
1990
- 1990-02-19 CA CA 2010381 patent/CA2010381A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0790116A3 (en) * | 1996-02-19 | 1999-11-24 | Fried. Krupp AG Hoesch-Krupp | Method for injection moulding three-layered moulded objects and apparatus for carrying out the method |
| WO1999052699A1 (en) * | 1998-04-08 | 1999-10-21 | Johnson Control S.P.A. | Injector for co-injection |
| WO2022040787A1 (en) * | 2020-08-24 | 2022-03-03 | Mold-Masters (2007) Limited | Injection molding apparatus having a valve pin decouplable from a valve pin plate |
| CN114872279A (en) * | 2022-04-27 | 2022-08-09 | 欧唐科技（深圳）有限公司 | Internal and external tooth demoulding device for plastic mould product |
| CN114872279B (en) * | 2022-04-27 | 2023-10-27 | 欧唐科技（深圳）有限公司 | Inner tooth and outer tooth demoulding device for plastic mould product |
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