MXPA98008711A - Molding apparatus for five layer injection with a four position valve member activation mechanism - Google Patents

Abstract

The present invention relates to a multiple cavity injection molding apparatus with valve controlled injection orifice for multi-layer molding having at least one manifold for distributing molten material with a front face and a plurality of nozzles heated assemblies in a mold, each heated nozzle has a rear end which is butted against the at least one manifold of distribution of molten material and a front end adjacent to an injection orifice leading to a cavity in the mold, each heated nozzle has a first channel of central molten material and second and third channels of molten material extending therethrough from the rear end to the front end, an elongated valve member having a rear end and a front end extending through at least one manifold of distribution of molten material within the channel of material fund At the center of each heated nozzle, the rear end of each elongate valve member is operatively connected to a valve member actuating mechanism mounted on the mold, a first passage of molten material to convey molten material from a first source of molten material is branches in the at least one melt distribution manifold, dividing to extend both around the elongated valve member in the first channel of molten core material and through the third channel of molten material in each heated nozzle to the injection orifice , and a second passage of molten material for transporting molten material from a second source of molten material branches in the at least one manifold of molten material distribution and extends through the second channel of molten material in each nozzle heated to the molten material. injection hole, the improvement in which: each ac mechanism Valve member pivoting reciprocally reciprocates the elongated valve member between a first closed position and second, third and fourth positions according to a predetermined continuous injection cycle, each valve member activation mechanism comprising: (a) means for retracting the valve member; valve member elongated from the first closed position to the second position in which the front end of the elongated valve member is retracted enough to allow the molten material coming from the first source of molten material to flow through the third channel of molten material in the heated nozzle and the injection orifice within the cavity for a predetermined period of time; (b) means for further retracting the elongated valve member to the third position in which the front end of the valve member elongated is retracted enough to allow the simultaneous flow of material fused from the second source of molten material through the second channel of molten material in the heated nozzle and from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice within the cavity during a predetermined period of time; (c) means for further retracting the elongate valve member to the fourth fully retracted open position in which the front end of the elongate valve member is retracted sufficiently to allow the simultaneous flow of the molten material which comes from the first source of molten material through the channel of molten material central in the heated nozzle, from the molten material coming from the second source of molten material through the second channel of molten material in the heated nozzle, and from the material melt that comes from the first source of molten material through the third channel of m fused material in the heated nozzle and injection port until the cavity is nearly full, (d) means for returning the elongate valve member to the second position afterwards until the cavity is filled, and (e) means for first driving the valve member elongated forward to the first closed position in which the front end of the elongated valve member is seated in the injection port to allow for expulsion

Description

MOLDING APPARATUS FOR INJECTION OF FIVE LAYERS WHICH HAS A MEMBER ACTIVATION MECHANISM OF V LVULA OF FOUR POSITIONS BACKGROUND OF THE INVENTION This invention relates generally to a multiple cavity injection molding apparatus for molding , five layers and more particularly to an apparatus having activation mechanisms for reciprocally moving elongated valve members between four different positions. Multiple cavity injection molding apparatuses are known for manufacturing five-layer protective containers for food to preforms for beverage bottles. Two layers of a barrier material such as ethylene vinyl alcohol (EVOH) or naylon copolymer are typically molded between two outer layers and a core layer of a polyethylene terephthalate (PET) type material. However, this has been done previously by first sequentially injecting the PET, then the barrier material and finally the PET again. Although this is satisfactory for some applications, sequential molding has the disadvantage that it requires relatively expensive tools. Also known are multi-injection injection molding apparatuses with valve controlled injection ports having mutually reciprocating elongated valve members. For example, the patent of E.U.A. No. 4,657,496 to Ozeki et al, issued April 14, 1987, shows an activation mechanism having an outer piston reciprocally moving in an outer cylinder and an inner piston reciprocatingly moving in an inner cylinder. The inner piston drives the elongated valve member and the outer piston drives a rod surrounding the elongated valve member and operates in a controlled injection cycle to sequentially mold three-layer products. None of the activation mechanisms of the prior art are capable of reciprocally moving the valve members between four different positions according to the present invention to provide five layer molding by simultaneous injection.

BRIEF DESCRIPTION OF THE INVENTION Accordingly, it is an object of the present invention to overcome "at least partially the disadvantages of the prior art by providing a multiple-cavity injection molding apparatus with a valve-controlled injection orifice for five-layer molding having activation mechanisms. of fluid to reciprocally move each elongated valve member between four different positions.

Up to this point, in one of its aspects, the invention provides an injection molding apparatus with injection orifice controlled by multiple cavity valve for multi-layer molding having at least one manifold for distributing molten material with one face front and a plurality of heated nozzles mounted in a mold. Each heated nozzle has a rear end that is spliced against the molten material distribution manifold and a front end adjacent to an injection orifice leading to a cavity in the mold. Each heated nozzle has a first channel of central molten material and second and third channels of molten material extending therethrough from the rear end to the front end. An elongated valve member has a trailing end and a front end that extend through the molten material distribution manifold within the central molten bath channel in each heated nozzle. The rear end of each elongate valve member is operatively connected to a valve member activation mechanism mounted in the mold. A first passage of molten material for transporting molten material from a first source of molten material branches into the molten material distribution manifold dividing to extend both around of the elongated valve member in the first channel of molten core material as through the third channel of molten material in each heated nozzle to the injection port. A second passage of molten material for transporting molten material from a second source of molten material branches in the manifold of molten material distribution and is understood through the second channel of molten material in each heated nozzle towards the injection orifice. Each valve member activation mechanism reciprocates the elongate valve member between a first closed position and a second, third and fourth positions according to a predetermined continuous injection cycle. Each valve member activation mechanism comprises means for retracting the elongate valve member from the first closed position to the second position in which the front end of the elongate valve member is retracted enough to allow the molten material that comes of the first source of molten material flows through the third channel of molten material in the nozzle and the injection orifice within the cavity for a predetermined period of time. It also comprises means for further retracting the elongate valve member to the third position in which the front end of the elongated valve member is retracted enough to allow the simultaneous flow of molten material from the second source of molten material through the second. channel of molten material in the nozzle and from the first source of molten material through the third channel of molten material in the nozzle and the injection orifice within the cavity for a predetermined period of time. Each triggering mechanism also includes means for further retracting the elongated valve member to the fourth fully retracted open position in which the front end of the elongated valve member is retracted sufficiently to allow the simultaneous flow of the molten material that comes from the first source of molten material through the channel of molten material central to the nozzle, of the molten material that comes from the second source of molten material through the second channel of molten material in the nozzle and of the molten material that comes from the first Source of molten material through the third channel of molten material in the nozzle and the injection orifice until the cavity is almost full. It also includes means for later returning the elongate valve member to the second position until the cavity is filled, and means for first urging the elongated valve member forward towards the first closed position in which the front end of the valve member Elongated valve is seated in the injection hole to allow ejection. In another of its aspects, the invention provides a multi-injection injection molding apparatus with injection orifice for multi-layer molding, having at least one manifold for distributing molten material with a front face and a plurality of nozzles heated mounted in a mold. Each heated nozzle has a rear end that is spliced against the molten material distribution manifold and a front end adjacent to an injection orifice leading to a cavity in the mold. Each heated nozzle has a first channel of central molten material and second and third channels of molten material extending therethrough from the rear end to the front end. An elongated valve member has a trailing end and a front end that extend through the molten material distribution manifold within the central molten material channel in each heated nozzle. The rear end of each elongate valve member is operatively connected to a valve member activation mechanism mounted in the mold. A first passage of molten material for transporting molten material from a first source of molten material branches into the molten material distribution manifold, dividing to extend both around the elongated valve member in the first channel of molten core material and through the third channel of molten material in each heated nozzle towards the injection orifice. A second passage of molten material for transporting molten material from a second source of molten material branches into the molten material distribution manifold and extends through the second channel of molten material in each heated nozzle to the injection port. Each valve member activation mechanism comprises a front cylinder and a rear cylinder, both aligned in the mold with each elongated valve member. A first piston is seated in the front cylinder and connected to the rear end of the elongated valve member. A second piston is seated in the rear cylinder. A third piston is seated behind the second piston in the rear cylinder. The third piston has a portion of the rod that extends forward through an opening in the second piston within the first cylinder. First and second fluid lines that come from fluid pressure means are connected to the front cylinder on opposite sides of the first piston. A third fluid line that comes from fluid pressure means is connected to the rear cylinder on the front side of the second piston, and a fourth fluid line that comes from fluid pressure means is connected to the rear cylinder on the rear side of the second cylinder. third piston. The fluid pressure applied through the first, second, third and fourth fluid pressure lines reciprocates the elongate valve member between a first closed position and second, third and fourth positions according to a predetermined continuous injection cycle. During this cycle, the fluid pressure coming from the second fluid line is first released and the fluid pressure is applied from the fourth fluid line to drive the second and third pistons forward, and fluid pressure is applied from the first fluid line for urging the first piston and the elongate valve member rearwardly from the first closed position until the trailing end of the first piston is engaged against the front end of the third piston in the second position. In the second position, the front end of the elongated valve member is retracted enough to allow the flow of molten material coming from the first source of molten material through the third channel of molten material into the nozzle and the injection orifice. . After a predetermined short period of time, the fluid pressure is applied from the third fluid line to drive the second piston to a rear position which allows the fluid pressure coming from the first fluid line to drive the first piston and the elongated member further forward towards the third position. In the third position, the front end of the elongated valve member is retracted enough to allow the simultaneous flow of the molten material coming from the second source of molten material through the second channel of molten material in the nozzle and of the molten material. which comes from the first source of molten material through the third channel of molten material in the nozzle and the injection orifice within the cavity. Then, the fluid pressure coming from the fourth fluid line is released and the fluid pressure coming from the first fluid line then urges the first and second pistons and the elongated valve member to the fourth fully retracted open position. In the fourth position, the front end of the elongated valve member is retracted enough to allow the simultaneous flow of the molten material coming from the first source of molten material through the central molten material channel in the nozzle, of the molten material that comes from the second source of molten material through the second channel of molten material in the nozzle, and from the molten material that comes from the first source of molten material through the third channel of molten material in the nozzle and the injection orifice . When the cavity is almost full, the fluid pressure coming from the third fluid line is released and the fluid pressure is reapplied from the fourth fluid line to propel the first, second and third pistons forward and return to the limb. elongated valve to the second position until the cavity is filled. Fluid pressure is then applied from the second fluid line to drive the first piston and the elongated valve member forward towards the first closed position in which the front end of the elongated valve member is seated in the valve orifice. injection for expulsion. In another of its aspects, the invention further provides a method for continuously injection molding multi-layer products in a multi-cavity injection molding apparatus having at least one manifold for distributing molten material with a front face and a plurality of heated nozzles mounted on a cast. Each heated nozzle has a rear end that is spliced against the molten material distribution manifold and a front end adjacent to an injection orifice leading to a cavity in the mold. Each heated nozzle has a first channel of central molten material and second and third channels of molten material extending therethrough from the rear end to the front end. An elongated valve member has a trailing end and a front end that extend through the molten material distribution manifold within the central molten bath channel in each heated nozzle. The rear end of each elongate valve member is operatively connected to a valve member activation mechanism mounted in the mold. A first passage of molten material for transporting molten material from a first source of molten material branches into the molten material distribution manifold, dividing to extend both "around the elongate valve member in the first channel of molten core material, and to through the third channel of molten material in each heated nozzle to the injection orifice A second passage of molten material for transporting molten material from a second source of molten material branches into the molten material distribution manifold and extends through the molten material. of the second channel of molten material in each heated nozzle to the injection port The method comprises the steps of first retracting the elongate valve member from a first closed position to a second position in which the front end of the elongated valve member is retracted enough to allow the material to The fluid coming from the first source of molten material flows through the third channel of molten material in the nozzle and from the injection orifice into the cavity for a predetermined period of time. It then comprises further retracting the elongate valve member to a third position in which the front end of the elongated valve member is retracted sufficiently to allow the simultaneous flow of the molten material coming from the second source of molten material through the second. channel of molten material in the nozzle and from the first source of molten material through the third channel of molten material in the nozzle and of the injection orifice within the cavity for a predetermined period of time. Then further retract the elongate valve member to a fourth fully retracted open position in which the front end of the elongate valve member is retracted enough to allow the simultaneous flow of the molten material that comes from the first source of molten material to the channel of molten material central in the nozzle, of the molten material that comes from the second source of molten material through the second channel of molten material in the nozzle, and of the molten material that comes from the first source of molten material through the third channel of molten material in the nozzle and injection hole until the cavity is almost full. It then comprises returning the elongated valve member to the second position until the cavity is filled, and finally urging the elongate valve member forward to the first closed position in which the front end of the elongated valve member is seated in the valve body. injection hole to allow ejection. Additional objects and advantages of the invention will become apparent from the following description taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a portion of a multiple cavity injection molding apparatus with valve controlled injection port according to a first embodiment of the invention, showing the elongated valve member in a first closed position, Figure 2 is a partial sectional view of the same apparatus, showing the elongate valve member in a second partially retracted position; Figure 3 is a similar view showing the elongated valve member in a third retracted position; Figure 4 is a similar view showing the elongated valve member in a fully retracted open fourth position; Figure 5 is an enlarged view of a portion of Figure 4 showing the flow of molten material within the cavity; and Figure 6 is a sectional view of a portion of a multi-cavity injection molding apparatus with injection orifice controlled by a valve Vula according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION * Reference is first made to Figure 1, which shows a portion of the multi-cavity injection molding apparatus with valve-controlled injection port for molding five-layer preforms or other products by a combination of co-injection sequential and simultaneous. As indicated above, two layers of a barrier material such as ethylene vinyl alcohol copolymer (EVOH) or nylon are molded between two outer layers and a core layer of a polyethylene terephthalate (PET) type material. However, they can be used in other material modalities having suitable characteristics. A number of heated nozzles 10 are mounted in a mold 12 with a rear end 14 abutting against the front face 16 of a steel front melt distribution manifold 1. Although the mold 12 may have a larger number of plates depending on the application, in this case, only a nozzle retention plate 20, a manifold retention plate 22 and a cylinder plate 24 fastened together by bolts 26, as well as a cavity retention plate are illustrated to simplify the illustration. 28. The front tip end 30 of each heated nozzle 10 is aligned with an injection orifice 32 that extends through a cooled injection port insert 34 into a cavity 36. This cavity 36 for manufacturing beverage bottle preforms it extends between a cavity insert 38 and the center of mold 40 in a conventional manner. Although only a single heated nozzle 10 is shown to simplify the illustration, in a typical configuration there will be many heated nozzles 10 (e.g., 32, 48 or 64) seated in the mold 12 and each aligned with an injection orifice 32 Each nozzle 10 is preferably heated by an integral electric heating element 42 having a terminal 44. Each heated nozzle 10 is seated in an opening 46 in the nozzle retaining plate 20 with a rear collar portion 48 of each nozzle. heated vessel 10 received in a circular locating seat 50 extending around the opening 46. This provides an insulating air space 52 between the heated nozzle 10 and the surrounding mold 12, which is cooled by pumping cooling water through ducts 54. Each heated nozzle 10 has a central molten material channel 56 extending from its rear end 14 to its front end at 30. In this shown configuration, each heated nozzle 10 has an insert portion 58 that is secured in a seat 60 by means of a threaded nozzle seal 62 that is screwed into place and that forms the front end end 30 of the heated nozzle 10. As best seen in Figure 2, the insert portion 58 is made of several pieces 64 that fit together to form a channel of interior annular fused material 66 that extends around the channel of molten material central 56 to the front end 30, and an outer annular melt channel 68 extending around the inner annular melt channel 66 and the central melt channel 56 to the front end 30. In this configuration, the heated nozzle 10 has a molten material bore. individual 70 extending from its rear end 14 to connect to the first or inner annular melt channel 64. A circle of spaced holes 72 is drilled in the rear end 14 of the heated nozzle 10 around the molten material hole 70 to provide thermal separation to the molten material flowing through the molten material hole 70. The configuration shown also has four separate molten material holes 74 extending from the rear end 14 of the heated nozzle 10 to the outer annular molten material channel 68. The first front cast material distribution manifold 18 is heated by an element of electric heating 76. This is located by a central locating ring 78 and screws 80 that extend inside each heated nozzle 10 to provide an insulating air space 82 that extends between it and the surrounding cooled mold 12. A second manifold The rear steel casting distribution 84 is mounted on the mold 12 by a number of insulating and elastic spacers 86 extending therebetween and the cylinder plate 24 to extend parallel to the front cast material distribution manifold 18. As shown in FIG. can observe, the two multiple 18, 84 are separated by insulating and thermally insulating melt transfer separators 88 placed therebetween. As described in more detail below, the rear melt distribution manifold 84 is heated by an integral electric heating element 90 to a lower operating temperature than the front melt distribution manifold 18, and the space of air 92 provided by the insulating and thermal melt transfer separators 88 between the two manifolds 18, 84 provides thermal separation therebetween. A first passage of molten material 94 extends from a common inlet 96 through a multiple cylindrical extension 98 and branches into the first front melt distribution manifold 18, and, in this configuration, extends through a molten material split bushing 100 seated on the front face 16 of the front cast material distribution manifold 18 in alignment with each heated nozzle 10. The molten material split bushing 100 is preferably made of three steel layers integrally welded between as described in copending Canadian application Serial No. 2,219,054, entitled "Injection Molding Apparatus Having Melt Dividing Bushings", concurrently filed with the present. In this configuration, the molten material division bushing 100 has a neck portion 102 which extends rearwardly through an opening 104 in the front melt distribution manifold 18 to the rear melt distribution manifold 84. The first passage of molten material 94 is divided again into each splitting bushing of molten material 100 and extends through the four holes of molten material 74 to the channel of outer annular molten material 66, as well as to the channel of material central melt 56 in each heated nozzle 10. A second passage of molten material 106 extends from a second inlet 108 and branches into the central molten distribution manifold 84 to extend through a central hole 110 in each transfer separator from molten material 88 to the aligned molten material hole 70 extending from the rear end 14 of each nozzle heated to the inner annular melt channel 66. An elongated valve member 112 having a rear head 114 and a front end 116 that fits into the injection port 32 extends through a hole 118 in the rear manifold. 84, through a central hole aligned 120 in the molten material division bushing 100 within the aligned central molten material channel 56 in each heated nozzle 10. Each elongated valve member 112 is reciprocally moved through four different positions during the injection cycle by an activation mechanism 122 mounted on the cylinder plate 24 according to the invention. The elongated valve member 112 is adapted in part to the central hole 120 in the molten material dividing bushing 100 tight enough to prevent spillage of molten material around the elongated valve member 112 while it reciprocates. Although hydraulic activation mechanisms 22 are shown, pneumatic activation mechanisms can, of course, be used for other applications. In this embodiment of the invention, the head 114 of the elongate valve member 112 is connected to a first piston 124 seated in a front cylinder 126. Each activation mechanism 122 also includes second and third pistons 128, 130 seated in a rear cylinder 132 aligned with the front cylinder 126. The third piston 130 is seated behind the second piston 128 and has a portion of rod 134 that extends forward through a hole 136 in the second piston 128 inside the front cylinder 126. As can be seen in FIG. note, first and second hydraulic lines 138, 140 extend to the front cylinder 126 on opposite sides of the first piston 124. A third hydraulic line 142 extends to the rear cylinder 132 on the front side of the second piston 128. A fourth hydraulic line 144 extends to the rear cylinder 132 on the rear side of the third piston 130. These hydraulic lines 138, 140, 142, 144 extend from a source (not shown) that applies hydraulic pressure to the different lines according to a predetermined program controlled by the injection cycle to reciprocate the elongate valve member 112 between first, second, third and fourth positions . During use, the injection molding system is assembled as shown in Figure 1 and functions to form five-layer preforms or other products as follows. First, electric power is applied to the heating element 76 in the front melt distribution manifold 18 and the heating elements 42 in the heated nozzles 10 to heat them to the operating temperature of the plastic material that will be injected through the channel of central molten material 56. In a preferred embodiment, this material is a polyethylene terephthalate (PET) type material having a melting temperature of about 296 ° C. Electric power is also applied to the heating element 90 in the rear melt distribution manifold 84 to heat it to the operating temperature of the plastic material which is injected through the inner annular melt channel 66. This is usually a material barrier such as ethylene vinyl alcohol copolymer (EVOH) having an operating temperature of about 204 ° C, but can also be nylon. Water is supplied to the cooling ducts 54 to cool the mold 12 and the injection orifice inserts 34. Hot pressurized molten material is then injected from separate injection cylinders (not shown) into the first and second passages of molten material. , 106 through inputs 96, 108 according to a predetermined injection cycle. As mentioned, the molten material injected into the first passage of molten material 94 is a polyethylene terephthalate (PET) type material. The first passage of molten material 94 branches in the front melt distribution manifold 18 and extends to each melt splitting bushing 100 where it splits again and flows into the central melt channel 56 of the nozzle. heated and aligned 10 around the elongated valve member 112, as well as in four separate holes 72 aligned with the four holes of molten material 74 at the rear end 14 of the heated nozzle 10 to the outer annular melt channel 68. Normally, as mentioned, the molten material injected into the second molten material passage 106 is a barrier material such as ethylene vinyl alcohol copolymer (EVOH) or nylon. The second passage of molten material 106 branches into the rear melt distribution manifold 84 and extends through the central hole 110 in each molten material transfer separator 88 and the aligned molten material hole 70 extending from the rear end of the heated nozzle 10 to the inner annular melt channel 66. As also seen in Figures 2, 3 and 4, the flow of PET coming from the first passage of molten material 94 and the barrier material that provided by the second passage of molten material 106 through each injection port 32 within the cavity 36 is controlled by the drive mechanism 122 reciprocally moving the elongated valve member 112 between first, second, third and fourth positions during the cycle of injection as follows. Initially, hydraulic pressure is applied from the second hydraulic line 140 to the front cylinder 126 behind the front piston 124 which drives the first piston 124 and the elongate valve member 112 forward in the direction of the first closed position shown in Figure 1 in the that the front end 116 of the elongate valve member 112 is seated in the injection port 32. Then, the hydraulic pressure of the second hydraulic line 140 is released, and hydraulic pressure is applied from the fourth hydraulic line 144 to the rear cylinder 132 behind of the third piston 130 which drives the second and third pistons 128, 130 forward. At the same time, fluid pressure is applied from the first hydraulic line 138 to the front cylinder 126 opposite the first piston 124, which drives the first piston 124 and the elongated valve member 112 back until they are stopped by the rear end 146 of the first piston 124 which is butted against the front end 148 of the stem portion 134 of the rear cylinder 132 in the second position. In this second position shown in Figure 2, the front end 116 of the elongate valve member 112 is sufficiently retracted to allow the PET to flow from the outer annular melt channel 68 through the injection port 32 to the cavity. 36. In this manner, a predetermined initial quantity of PET 149 is injected into the cavities 36 through the first passage of molten material 94, and part of it adheres to the sides 150 of the cavities 36.

Shortly after the start of the PET injection, hydraulic pressure is applied from the third hydraulic line 142 to the rear cylinder 132 opposite the second piston 128, which drives the second piston 128 to a rear position against the detent 152. This allows the the hydraulic pressure coming from the first hydraulic line 138 drives the first piston 124 and the elongated valve member 112 further back to the third position. In this third position shown in Figure 3, the front end 116 of the elongated valve member 112 is retracted further enough to allow both the PET coming from the outer annular melt channel 68 and the barrier material coming from the inner annular melt channel 66 are simultaneously co-injected through the injection port 32 to the cavity 36. As can be seen, the flow of the less viscous barrier material divides the PET flow into two outer layers 154. After the simultaneous flow of PET and the barrier material has been established, the hydraulic pressure of the fourth hydraulic line 144 is released and the hydraulic pressure of the first fluid line 138 then urges the first and second pistons 124, 128 and the valve member elongated to the fourth open position fully retracted. In this fourth open position shown in Figures 4 and 5, the front end of the elongate valve member 112 is retracted further enough to also allow the simultaneous flow of PET from the central molten material channel 56 through the injection port. 32 to the cavity 36. As can be seen in Figure 5, this internal flow of PET, in turn, divides the flow of the barrier material into two layers 156 on both sides of an inner layer 158 of PET. When the cavities 36 are almost full, the hydraulic pressure coming from the third hydraulic line 142 is released and hydraulic pressure is reapplied from the fourth hydraulic line 144, which drives the first, second and third pistons 124, 128, 130 forward and returns to the elongated valve member 112 to the second position shown in Figure 2, which stops the flow of the barrier material. After another small amount of PET has been injected to complete the filling of the cavities 36, the hydraulic pressure is then released from the fourth hydraulic line 144 and reapplied from the second hydraulic line 140 to return to the first piston 124 and to the elongate valve 112 to the first closed position. After a short cooling period, the mold 12 is opened for ejection. After ejection, the mold is closed and the injection cycle is repeated continuously every 15 to 30 seconds with a frequency that depends on the wall thickness and the number and size of cavities 36, as well as the exact materials being molded .

Reference is now made to Figure 6, which shows the injection molding apparatus according to another embodiment of the invention for injection-molded orifice controlled valve with five-layer preforms or other products by a combination of sequential and simultaneous co-injection. As many of the elements are the same or similar to those described above, not all the elements common to both modalities are described again, and those that are described again have the same reference numbers as above. In this case, the rear melt distribution manifold 48 instead of the front melt distribution manifold 18 has the multiple extension 98. In this way, the first passage of molten material 94 extends from the inlet 96 in the manifold extension 98 and branches into the rear cast material distribution manifold 84 instead of the manifold 18 of the front melt material 18. More, the second passage of molten material 106 extends from the second inlet 108 through the front melt distribution manifold 18 instead of the rear cast material distribution manifold 84. As can be seen, a transfer and split bushing Molten material 160 is mounted behind each heated nozzle 10 in a cylindrical opening 162 that extends through the front molten material manifold 118 with its front end 134 butting against the rear end 14 of the heated nozzle 10. In this embodiment, the back end 166 of the molten material transfer and split bushing 160 is spliced against the rear cast material distribution manifold 84 with a neck portion 168 extending into an aperture 170 in the rear cast material distribution manifold 84, but in other embodiments, the rear end 166 of the transfer hub and material division the melt 160 can be seated in the rear cast material distribution manifold 84. Each molded material transfer and division bushing 160 is made integrally with each other a first steel layer 172 at its trailing end 166 with the neck portion 168. , a third steel layer 174 at its front end 164 and a second steel layer 176 between the first and third layers 172, 174, as described in the co-pending Canadian application Serial No. 2,219,197, entitled "Injection Molding Apparatus Having Melt Transfer and Dividing Bushing ", presented concurrently with the present. The first back layer 172 has a hole 178 extending therethrough from an inlet 180 at the rear end 166. The third front layer 174 has four holes 182 that extend through it to four openings 184, each aligned with one of the four holes of molten material 74 that extend to the outer annular channel 68 in the heated nozzle 10. The front face 186 of the first back layer 172 and the back face 188 of the second layer 176 are machined to have matching grooves that join when the three layers are joined together to form a first molten material conduit 190 that branches to extend from the hole 178 in the first back layer 172 to a central hole 192 through the transfer bushing and dividing molten material 160, as well as two separate holes (not shown) extending through second layer 176 to two exits on front face 194 of the second layer 176. The front face 194 of the second layer 176 and the rear face 196 of the third front layer 174 are also machined to have two matching slots that join when the three layers are joined together to form two second passages. of curved cast material 198. Each second curved cast material conduit 198 branches from one of the outlets that come from the holes through the second layer, to two of the four separate holes 182 that extend through the third layer 174 to the four outlets 184 at the front end 164 of the molten material transfer and split bushing 160. Each of these four outlets 184 is aligned with one of the four holes of molten material 74 extending from the rear end 14 of the heated nozzle 10 to the outer annular fused material channel 168. In this manner, the first passage of molten material 94 which branches into the manifold of rear cast material distribution 84 to each transfer bushing and melt division 160 is divided again as it passes through each molten material transfer and separation bushing 160 to extend to the central molten material channel 56 and the secondary channel. outer annular fused material 68 in each heated nozzle 10. In this embodiment, the third frontal layer 174 of each molded material transfer and division bushing 160 has a passage of molten material 200 in L-shape aligned with the second passage of molten material 106 which branches into the front molten material distribution manifold 18 and the material hole individual melt 70 extending from the rear end 14 of the heated nozzle 10 to the inner annular melt channel 66 to form part of the second passage of molten material 106. A small pin 202 extends from a transfer and division bushing cast material 160 within the rear cast material distribution manifold 84 for locating the melt transfer and splitting bushing 160 with the four separate outlets 184 in alignment with the four holes of molten material 74 extending from the rear end 14 of the heated nozzle 10 to the outer annular channel 68. The operation of this embodiment of the in This is the same as the one described above and does not need to be repeated. Although the description of the injection molding apparatus with valve controlled injection orifice for the five layer molding has been given with respect to preferred embodiments, it will be evident that various modifications are possible without departing from the scope of the invention, as understood by those skilled in the art and defined in the following claims. For example, other materials having suitable characteristics can be used instead of PET, EVOH and naylon. The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

Claims (12)

NOVELTY OF THE INVENTION CLAIMS

1. - In a multiple-cavity injection molding apparatus with valve controlled injection orifice for multi-layer molding having at least one manifold for distributing molten material with a front face and a plurality of heated nozzles mounted in a mold Each heated nozzle has a rear end that is spliced against the at least one melt distribution manifold and a front end adjacent to an injection orifice leading to a cavity in the mold, each heated nozzle has a first flute channel. central molten material and second and third channels of molten material extending therethrough from the trailing end to the front end, an elongated valve member having a trailing end and a front end extending through at less a distribution manifold of molten material within the central molten material channel in each nozzle When the rear end of each elongate valve member is operatively connected to a valve member actuating mechanism mounted on the mold, a first passage of molten material for transporting molten material from a first source of molten material is branched at the bottom. at least one distribution manifold of molten material, dividing to extend both around the elongate valve member in the first channel of molten core material and through the third channel of molten material in each heated nozzle to the injection orifice, and one second passage of molten material for transporting molten material from a second source of molten material branches in the at least one manifold of distribution of molten material and extends through the second channel of molten material in each heated nozzle to the injection orifice, the improvement in which; each valve member activation mechanism reciprocates the elongate valve member between a first closed position and second, third and fourth positions according to a predetermined continuous injection cycle, each valve member activation mechanism comprising: (a) means for retracting the elongate valve member from the first closed position to the second position in which the front end of the elongate valve member is retracted enough to allow the molten material coming from the first source of molten material to flow to through the third channel of molten material in the heated nozzle and the injection orifice within the cavity for a predetermined period of time; (b) means for further retracting the elongated valve member to the third position in which the front end of the elongate valve member is retracted enough to allow the simultaneous flow of molten material from the second source of molten material through from the second channel of molten material in the heated nozzle and from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice within the cavity for a predetermined period of time; (c) means for further retracting the elongated valve member to the fourth fully retracted open position in which the front end of the elongated valve member is retracted sufficiently to allow the simultaneous flow of molten material from the first source of molten material through the channel of molten core material in the heated nozzle, of the molten material coming from the second source of molten material through the second channel of molten material in the heated nozzle, and of the molten material that comes from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice until the cavity is nearly full; (d) means for later returning the elongated valve member to the second position until the cavity is filled, and (e) means for first urging the elongated valve member forward to the first closed position in which the front end of the valve member Elongated valve member is seated in the injection hole to allow ejection.

2. - The injection molding apparatus according to claim 1, further characterized in that the second channel of molten material through each heated nozzle includes a channel of inner annular fused material that extends around the central molten material channel to the extreme front, and the third channel of molten material through each heated nozzle includes an outer annular fused material channel extending around the inner annular molten material channel to the front end.

3. The injection molding apparatus according to claim 2, further characterized in that the molten material coming from the first source is polyethylene terephthalate (PET).

4. The injection molding apparatus according to claim 3, further characterized in that the molten material coming from the second source is ethylene-vinyl alcohol copolymer (EVOH).

5. The injection molding apparatus according to claim 3, further characterized in that the molten material coming from the second source is nylon.

6. The injection molding apparatus according to claim 2, further characterized in that the first and third passages of molten material that come from the first source of molten material are branched into a manifold of distribution of front molten material mounted on the mold, and the second passage of molten material that comes from the second source of molten material branches into a manifold of distribution of molten back material mounted on the mold.

7. The injection molding apparatus according to claim 3, further characterized in that the front melt distribution manifold extends substantially parallel to, and spaced a predetermined distance from, the subsequent molten material distribution manifold, and the second passage of molten material that comes from the second source of molten material branches into the subsequent molten material distribution manifold and then extends through holes of molten material in the front molten material distribution manifold.

8. The injection molding apparatus according to claim 2, further characterized in that the first and third passages of molten material coming from the first source of molten material are branched into a manifold of subsequent molten material mounting on the mold, and the second passage of molten material that comes from the second source of molten material is ramped into a manifold of distribution of front molten material mounted in the mold.

9. The injection molding apparatus according to claim 8, further characterized in that the front melt distribution manifold extends substantially parallel to, and is spaced a predetermined distance from, the subsequent molten material distribution manifold, and the first and third passages of molten material that come from the first source of molten material are branched into the manifold of distribution of molten back material and then extend through holes of molten material in the manifold of distribution of the molten front material.

10. In a multiple-cavity injection molding apparatus with valve controlled injection orifice for multi-layer molding having at least one manifold for distributing molten material with a front face and a plurality of heated nozzles mounted on a mold, each heated nozzle has a rear end that is spliced against the at least one manifold of distribution of molten material and a front end adjacent to an injection orifice leading to a cavity in the mold, each heated nozzle has a first channel of molten core material and second and third channels of molten material extending therethrough from the trailing end to the front end, an elongated valve member having a trailing end and a front end which extend through at least one molten material distribution manifold within the central molten material channel in each heated nozzle, the trailing end of each member of elongate valve is operatively connected to a valve member activation mechanism mounted on the mold, a first passage of molten material for transporting molten material from a first source of molten material branches into the at least one material distribution manifold melted, dividing to extend both around the elongate valve member in the first channel of molten core material and through the third channel of molten material in each heated nozzle to the injection orifice, and a second passage of molten material to convey molten material from a second source of molten material branches into the at least s a manifold of distribution of molten material and extends through the second channel of molten material in each heated nozzle to the injection orifice, the improvement in which; each valve member activation mechanism comprises a front cylinder and a rear cylinder both aligned in the mold with each elongated valve member, a first piston seated in the front cylinder and connected to the rear end of the elongated valve member, a second piston seated in the rear cylinder and a third piston seated behind the second piston in the rear cylinder, the third piston has a portion of the rod extending forward through an opening in the second piston within the first cylinder, first and second lines of fluid coming from fluid pressure means connected to the front cylinder on opposite sides of the first piston, a third fluid line that comes from fluid pressure means connected to the rear cylinder on the front side of the second piston, and a fourth line of fluid that comes from fluid pressure means connected to the posterior cylinder on the rear side of the third piston, whereby fluid pressure is applied through the first, second, third and fourth fluid pressure lines reciprocally reciprocally move the elongated valve member between a first closed position and second, third and fourth positions according to a predetermined continuous injection cycle in which the fluid pressure coming from the second fluid line is released first, and fluid pressure is applied from the fourth fluid line to drive the second and third pistons forward and fluid pressure is applied from the first fluid line to drive the first piston and the elongate valve member backwardly from the first closed position until the trailing end of the first piston is butted against the front end of the third piston in the second position wherein the front end of the elongate valve member is retracted sufficiently to allow the flow of molten material that comes from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice, after a short predetermined period of time, fluid pressure is applied from the third fluid line to driving the second piston to a rear position which allows the flow pressure coming from the first fluid line to drive the first piston and the elongate valve member further back to the third position in which the front end of the valve member elongate is sufficiently retracted to allow the simultaneous flow of the molten material coming from the second source of molten material through the second channel of molten material in the heated nozzle, and of the molten material coming from the first source of molten material to the molten material. through the third channel of molten material in the heated nozzle and the injection hole of the cavity, and then the fluid pressure of the fourth fluid line is released and the fluid pressure coming from the first fluid line then urges the first and second pistons and the elongated valve member to the fourth open position fully retracted in which the front end of the elongated valve member is retracted sufficiently to allow the simultaneous flow of the molten material coming from the first source of molten material through the channel of molten core material in the heated nozzle, of the material melt coming from the second source of molten material through the second channel of molten material in the heated nozzle, and from the molten material coming from the first source of molten material through the third channel of molten material in the heated nozzle and the injection hole, when the cavity is almost full, the fluid pressure from the third fluid line is released and reapplies fluid pressure from the fourth fluid line to propel the firstsecond and third pistons forward and return the elongate valve member to the second position until the cavity is filled, and then fluid pressure is applied from the second fluid line to drive the first piston and elongated valve member toward forward to the first closed position in which the front end of the elongated valve member is seated in the injection hole to allow ejection.

11. The injection molding apparatus according to claim 10, further characterized in that the second channel of molten material through each heated nozzle includes a channel of inner annular fused material extending around the central molten material channel. the front end, and the third channel of molten material through each heated nozzle includes an outer annular melt channel extending around the interior annular melt channel to the front end.

12. A method for continuously molding multi-layer products in a multi-cavity injection molding apparatus having at least one manifold for distributing molten material with a front face and a plurality of heated nozzles mounted in a mold , each sung mouthpiece has a rear end that is spliced against the at least one manifold of distribution of molten material and a front end adjacent to an injection orifice leading to a cavity in the mold, each heated nozzle has a first channel of central molten material and second and third channels of molten material extending therethrough from the trailing end to the front end, an elongated valve member having a trailing end and a front end extending through the less a distribution manifold of molten material within the central molten material channel in each nozzle In this case, the rear end of each elongated valve member is operatively connected to a valve member activation mechanism mounted in the mold.; a first passage of molten material for transporting molten material from a first source of molten material branches into the at least one manifold of distribution of molten material, dividing to extend both around the elongated valve member in the first channel of molten core material , as through the third channel of molten material in each heated nozzle to the injection orifice, and a second passage of molten material for transporting molten material from a second source of molten material branches into the at least one manifold molten material and extending through the second channel of molten material in each heated nozzle to the injection orifice; comprising the steps of: (a) retracting the elongated valve member from a first closed position to a second position in which the front end of the elongate valve member is retracted sufficiently to allow the molten material coming from the first source of molten material flows through the third channel of molten material in the heated nozzle and the injection orifice within the cavity for a predetermined period of time; (b) further retracting the elongated valve member to a third position in which the front end of the elongated valve member is retracted enough to allow the simultaneous flow of molten material coming from the second source of molten material through the second channel of molten material in the heated nozzle and from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice within the cavity for a predetermined period of time; (c) further retracting the elongate valve member to a fourth fully retracted open position in which the front end of the elongated valve member is retracted enough to allow the simultaneous flow of the molten material that comes from the first source of molten material to the channel of molten material central in the heated nozzle, of the molten material coming from the second source of molten material through the second channel of molten material in the heated nozzle, and of the molten material that comes from the first source of molten material through the third channel of molten material in the heated nozzle and the injection orifice until the cavity is almost full; (d) returning the elongate valve member to the second position after the cavity is filled, and (e) urging the elongated valve member forward to the first closed position in which the front end of the elongated valve member it is seated in the injection hole to allow the expulsion.SUMMARY OF THE INVENTION A multiple-cavity injection molding apparatus with a valve-controlled injection orifice for five-layer molding having drive mechanisms for reciprocating elongated valve members between four different positions is described; each activation mechanism has cylinders aligned front and rear, a first piston connected to the head of one of the valve members in the front cylinder, and second and third pistons in the rear cylinder; the third piston has a portion of the rod that extends forwardly through the second piston inside the front cylinder; hydraulic pressure that comes from four hydraulic lines connected to each activation mechanism reciprocally moves each elongated valve member between the different positions; in the first closed position, the front end of the valve member is seated in the injection hole; in the second position, the front end of the valve member is retracted enough to allow an initial amount of PET to flow from an outer annular melt channel through the injection port; then the valve member is further retracted to a third position to allow the simultaneous flow of the PET and a barrier material from an inner annular melt channel; then the valve member is retracted to a fully open position allowing the simultaneous flow of PET from a channel of central molten material; when the cavity is almost full, the valve member briefly returns to the second position for filling before returning to the second closed position for ejection. JN / blm * mmr * ehp * amm * xal * P98 / 1118