Specification
Title of invention: Stretch blow molding apparatus and blow molding method
Technical field
[0001]
　TECHNICAL FIELD The present invention relates to a stretch blow molding apparatus and a blow molding method for molding a hollow molded body from a preform.
Background technology
[0002]
　Conventionally, in a device for molding a hollow molded article by blowing air, as a method of direct blow molding, a cylindrical molten resin called a parison extruded from an extruder as shown in Patent Document 1 After sandwiching it with a half blow mold, apply a blow pin to the part that will be the opening in the molded body, blow cooling compressed air from the blow pin into the cylindrical molten resin, and inflate the molten resin by the blowing Of the blow mold is cooled by coming into contact with the hollow molded body forming surface of the inner surface of the blow mold, and after the cooling, compressed cooling air is exhausted from the hollow molded body.
[0003]
　In Patent Document 1, after blowing compressed air for cooling to cool the compressed air for cooling inside the hollow molded body from the tip of the blow pin, the blow pin is slightly raised from the blow mold to A technique is disclosed in which a compressed air for cooling, which is in a high pressure state in the hollow molded body, is allowed to escape by providing a gap between the blow pin and the inner surface of the opening of the hollow molded body that is shaped in the shape of. ..
[0004]
　Further, in the same blow molding method by direct blow molding as described in Patent Document 2, compressed air is blown in and exhausted together after the hollow molded body is molded. The point is that the internal gas pressure is set to a predetermined pressure and the flow rate is set so that compressed air is blown while being exhausted.
[0005]
　In the technique of Patent Document 2, after the cylindrical molten resin extruded from the extruder is sandwiched by the blow molds as described above, the blow pin is applied to the nozzle portion of the mold, the solenoid valve is opened, and the compression is performed. Air is sent into the parison, and the parison swells and is pressed against the mold surface of the mold to form a hollow molded body. After the hollow molded body is molded, when the internal pressure of the hollow molded body reaches the set value of the relief valve, the compressed air blown into the hollow molded body is exhausted out of the mold.
[0006]
　Similarly, in direct blow molding, Patent Document 3 discloses that hot air in the hollow molded body is discharged to the outside of the hollow molded body while the pressure in the hollow molded body is maintained at a predetermined pressure by blowing air or the like.
[0007]
　In this Patent Document 3, a matching mold having a parison is closed, and air is blown into the parison from an outlet of a blowing nozzle portion arranged at the center of an air blowing/discharging nozzle to stabilize the parison in a substantially columnar shape. In the hollow molded body, when the pressure in the hollow molded body reaches a predetermined pressure, the air in the hollow molded body is discharged from the discharge nozzle portion arranged around the blowing nozzle portion of the air blowing and discharging nozzle, The blown air from the blow-in nozzle part inflates the hollow molded body, and the air that has performed the expanding action is discharged outside the hollow molded body from the discharge nozzle part accompanied by hot air, preventing hot air from staying and promoting cooling. It is shown.
[0008]
　Also, in stretch blow molding, which is different from direct blow molding, a preform that can be shaped at high temperature is placed in a blow mold that is a split mold, and the rod enters from the side that will be the mouth of the preform. The preform is stretched in the axial direction of the rod, and compressed air is blown into the preform so that the preform is brought into contact with the inner surface of the blow mold to form the hollow molded body.
[0009]
　When the preform is stretched and compressed air is blown into it to form a hollow molded body, for example, as shown in Patent Document 4, a blow core in which a rod is movably arranged is provided with a passage through which compressed air passes. It is shown that compressed air is blown into the preform to inflate it through this passage, and after the preform has the shape of a hollow molded body, exhaust is performed through the passage.
Prior art documents
Patent literature
[0010]
Patent Document 1: JP-A-10-006391 Patent Publication
Patent Document 2: JP-A 09-131784 JP-
Patent Document 3: JP-A 03-013313 JP
Patent Document 4: JP-A 05-237923 JP
Summary of the invention
Problems to be Solved by the Invention
[0011]
(Injection stretch blow molding machine) There
　is an injection stretch blow molding machine as an apparatus for producing a hollow molded article using the above stretch blow molding method. FIG. 1 shows an injection stretch blow molding machine 1. This injection stretch blow molding machine 1 is connected to an injection device 2 and is fed with a molten resin, and an injection molding section 3 for molding a preform, and a state in which the injection molding blow molding machine 1 is molded by the injection molding section 3 and can be shaped at a high temperature. Blow molding section 4 for molding the above preform into a hollow molded article, and a take-out section for carrying out the hollow molded article molded by the stretch blow molding section 4 to the outside of the injection stretch blow molding machine 1. 5 and.
[0012]
　In the above-mentioned injection stretch blow molding machine 1, a lip mold 6 to be described later is rotated, and a plurality of preforms molded in the injection molding section 3 are combined as a set and conveyed to the stretch blow molding section 4, where the stretch blow molding is performed. The injection molding section 3 is sequentially arranged along the direction around the center of the injection stretch blow molding machine 1 so that a plurality of blow molded articles blow-molded by the molding section 4 can be conveyed as a set to the take-out section 5. The stretch blow molding section 4 and the take-out section 5 are arranged. See Figure 2
[0013]
　Then, a lip die 6 for molding the outer peripheral surface of the preform mouth portion and also for conveying the preform is provided so as to sequentially move the injection molding portion 3, the stretch blow molding portion 4, and the take-out portion 5. The rotary plate 7 having the lip mold 6 on its lower surface is stopped and lifted at every rotation of a fixed rotation angle, and the lip mold 6 is stretched and blow-molded by the injection molding unit 3 every time the rotary plate 7 descends. Corresponding to the section 4 and the take-out section 5, the preform molded by the injection molding section 3 is supported by the lip mold 6 and conveyed to the stretch blow molding section 4, and the hollow molding molded by the stretch blow molding section 4 is carried out. The body is supported by the lip mold 6 and conveyed to the take-out section 5, and one cycle is made until the hollow-molded article is sent out of the take-out section 5 to the outside of the molding machine to produce the hollow-molded article. The injection molding section 3, the stretch blow molding section 4, and the take-out section 5 are arranged so that they are arranged every 120° in the moving direction of the lip mold 6.
[0014]
(Stretch Blow Molding Device) In the
　stretch blow molding unit 4, as shown in FIG. 3, a stretch blow molding device 11 including a blow mold 8, a stretching device 9, and a blowing device 10 is configured. The blow mold 8 in the stretch blow molding apparatus 11 is a split mold, and a preform that can be shaped at a high temperature can be placed in a state of being supported by the lip mold 6, and the blow mold 8 can be placed on the inner surface of the mold. Has a hollow molded body shape forming surface.
[0015]
(Stretching device)
　The stretching device 9 in the stretch blow molding device 11 is provided with a rod 12 that can move up and down through the lip mold 6 that is superposed on the upper part of the blow mold 8 and enter the inside of the blow mold 8. There is. The rod 12 is supported by a rod mounting body 13, and when the rod mounting body 13 descends, the rod 12 descends through a central portion of the lip mold 6 and is supported by the lip mold 6 and disposed on the blow mold 8. In addition, when the rod 12 enters the inside of the preform and the rod 12 is moved downward (downward in the rod axial direction), the preform is stretched in the axial direction of the rod.
[0016]
(
　Blow-In Device) In the blow-in device 10 of the stretch blow molding device 11, as shown in FIG. 4, a cylindrical blow core 15 having a core passage 14 through which the compressed air a flows and the rod 12 passes. Is supported by the blow core mounting body 16, and the blow core 15 can be moved up and down by raising and lowering the blow core mounting body 16.
[0017]
　Then, by lowering the blow core 15 and fitting the lower part of the blow core 15 into the inside of the lip mold 6, the portion of the core internal passage 14 of the blow core 15 is made into the internal space of the preform b in the mold of the blow mold 8. The compressed air a is blown into the inside of the preform b which is made to communicate with c and is stretched by the rod 12 that descends the core internal passage 14 through the internal core passage 14, and the preform b is expanded by the compressed air a and hollowed. The blow operation for forming the molded body d is performed.
[0018]
　As described above, the stretch blow molding device 11 includes the blow mold 8, the stretching device 9, and the blowing device 10. The blow mold 8 is expanded by expanding the preform b stretched by the stretching device 9 in the mold of the blow mold 8. The shape of the hollow molded body d is shaped by bringing it into contact with the hollow molded body shape forming surface of No. 8, and the temperature of the hollow molded body d itself is lowered by bringing the hollow molded body d into contact with the blow mold 8. As a result, a hollow molded body d having a stable shape is formed.
[0019]
　In the blowing device 10, as shown in FIGS. 5 and 6, compressed air is stored in the air tank 19 from the compressor 18 such as a compressor, and the compressed air is taken out from the air tank 19 by the pressure reducing valve 20 to a low pressure. A first compressed air supply source 21 is connected to blow a low pressure compressed air into the preform through the in-core passage 14 and inflate the preform with the low pressure compressed air. It is designed so that a road can be formed.
[0020]
　Further, in the blowing device 10, after the shaping by the low pressure compressed air is performed, the flow path for blowing the high pressure compressed air is formed. A second compressed air supply source 22 adapted to take out high-pressure air from the air tank 19 is also connected to the blowing device 10, and the shaped hollow molded body is brought into close contact with the blow mold to blow mold side. In order to make the effect of the cooling from the inside more effective, it is possible to form a flow path for high pressure blowing in which high pressure compressed air is blown into the preform through the in-core passage 14.
[0021]
　Then, in the blowing device 10, after the high-pressure compressed air is blown through the high-pressure blowing passage to cool the hollow molded body, the compressed air is discharged from the hollow molded body to the outside of the core mold through the core internal passage 14. The flow path is formed.
[0022]
　In the blowing device 10 shown in FIGS. 5 and 6, the flow of compressed air is switched between when low-pressure compressed air is blown into the preform and when high-pressure compressed air is blown into the shaped hollow molded body. Therefore, a solenoid valve 23 for opening and closing the flow passage is attached to each of the flow passages so that the compressed air can be discharged to the outside of the core mold when necessary. Further, a check valve 24 is attached to a portion of a flow passage for blowing low-pressure compressed air into the preform, and a silencer 25 is attached to an end portion of the flow passage for exhausting air.
[0023]
　Note that FIG. 5 shows a state in which low-pressure compressed air is blown in. The electromagnetic valve 23 in the low-pressure blow passage is opened, the electromagnetic valve 23 in the high-pressure blow passage is closed, and the exhaust valve for exhaust is shown. The electromagnetic valve 23 in the flow path is closed. FIG. 6 shows a state in which high-pressure compressed air is blown in. The electromagnetic valve 23 of the low-pressure blow passage is closed, the electromagnetic valve 23 of the high-pressure blow passage is opened, and the electromagnetic passage 23 of the exhaust passage is opened. The solenoid valve 23 is closed. Although not shown, only the electromagnetic valve 23 in the exhaust passage is opened during exhaust.
[0024]
　In the blow molding, as described above, during the blow operation from the expansion of the preform b to the temperature reduction of the hollow molded body d itself until the shape of the hollow molded body d becomes stable, no exhaust is performed outside the blow mold. Compressed air is blown in under the condition.
[0025]
　However, in the blow molding in this case, the cooling efficiency becomes poor. That is, the internal space c of the hollow molded body d formed by the swelling of the preform b has no exhaust air to the outside, and the compressed air a heated by receiving heat from the preform b or the hollow molded body d in an adiabatic state is used. Therefore, the hollow molded body d is cooled with compressed air a, and the efficiency is low.
[0026]
　Therefore, in the stretch blow molding in the above-mentioned stretch blow molding apparatus in the conventional injection stretch blow molding machine, in order to form a hollow molded body by inflating the preform outside the blow mold under a non-exhausted state, compressed air is used. In the shaping step of blowing and inflating to make the shape of the hollow molded body, and under the condition that it can be exhausted outside the blow mold, the hollow molded body is brought into direct contact with the blow mold to lower the temperature and In order to exhaust heat from the internal space by ventilation to the outside of the blow mold and cool it from the internal space side, a cooling step of blowing compressed air is provided.
[0027]
　Furthermore, in recent years, the injection stretch blow molding machine has been able to shorten the molding cycle of the hollow molded body by shortening the time required for preform molding of the injection molding part. Then, a mechanism is provided to shorten the time required for the blow operation in the stretch blow molding section of this injection stretch blow molding machine.
[0028]
　Specifically, in the stretch blow molding apparatus, the pressure of the compressed air blown in the shaping step (non-exhaust) for inflating and the pressure of the compressed air blown in the cooling step (exhaust outside the blow mold) are different. I am trying. In order to make the pressure of the compressed air different between the shaping step and the cooling step, the blowing device has the following configuration.
[0029]
　Also in this blowing device 10, as in the case of the blowing device 10 described above, the blow core mounting body 16 is made to support the cylindrical blow core 15 having the internal passage 14 through which the compressed air a flows and the rod 12 passes. The blow core 15 can be moved up and down by raising and lowering the blow core mounting body 16. See Figure 7
[0030]
　In addition, an in-rod passage 17 is also formed inside the rod 12, and the rod 12 enters the inside of the preform by the lowering of the rod mounting body 13, and the in-rod passage 17 is formed through the through hole 26. It is designed to communicate with the internal space c of b.
[0031]
　Then, by lowering the blow core 15 and fitting the lower part of the blow core 15 into the inside of the lip mold 6, the portion of the core internal passage 14 of the blow core 15 is made to have the internal space c of the preform b in the mold of the blow mold 8. The compressed air a is blown into the inside of the preform b which is made to communicate with the inside of the preform b which is extended by the rod 12 which descends the core internal passage 14, and the preform b is inflated by the compressed air a, and the rod 12 The compressed air a is blown through the rod inner passage 17 to perform the blow operation to obtain the hollow molded body d.
[0032]
　As shown in FIGS. 8 and 9, the flow path of the blowing device 10 is configured by adding a new pipeline for passing compressed air to the flow path of the blowing device 10 described above shown in FIGS. 4 to 6. There is. In this blowing device 10, two first and second compressed air supply sources 21 and 22 configured to take out compressed air from the air tank 19 are connected to each other, and compressed air a is supplied to the core passage 14 and the rod. A compressed air flow path 27 is formed which enters the inside of the preform through the passage 17 and flows from the inside of the preform through the in-core passage 14 to the exhaust space outside the blow mold to be exhausted. ..
[0033]
　Of course, the compressed air flow path 27 which allows compressed air to enter the preform and to be exhausted (ventilation of the internal space of the hollow molded body) after entering the hollow molded body is provided in the lip mold 6 with the blow core 15 And the rod 12 is located inside the preform through the blow core 15.
[0034]
　Regarding the flow path in the blowing device 10 shown in FIGS. 7 to 9, as described above, the high-pressure blowing flow path X of the blowing device 10 which blows by non-exhaust air in FIGS. 4 to 6 is left. The morphology is depicted in the figure. That is, in the blowing device 10 shown in FIGS. 7 to 9, a high-pressure blow can be performed without exhaustion without passing compressed air through the newly added flow passage. It has a configuration. In addition, the following description is for a usage mode in which compressed air is not passed through the flow path X for performing non-exhaust high-pressure blowing.
[0035]
　As shown in the figure, a first compressed air supply source 21 is connected to the compressed air flow path 27, and a preform b that can be shaped at a high temperature and is placed in the mold of the blow mold 8 is formed. In the internal space c of the shaping object e, there is a first inflow passage 28 that allows compressed air to flow from the first compressed air supply source 21 through the in-core passage 14.
[0036]
　In addition, the second compressed air supply source 22 is connected to the internal space c of the shaping object e at the stage of being placed in the mold of the blow mold 8 and having the shape of the hollow molded body d by shaping. The rod inner passage 17 through which the compressed air a flows from the second compressed air supply source 22 and the rod inner passage 17 are the object e to be shaped (the preform is a hollow molded body) There is a second inflow passage 29 that allows compressed air to flow through the plurality of through holes 26 that are opened so as to communicate with the internal space c.
[0037]
　Further, there is an outflow passage 30 that allows compressed air a to flow from the internal space c of the shaping object e through the in-core passage 14 to the exhaust space outside the blow mold. The outflow passage 30 itself is the same as the flow passage for exhausting to the outside of the core mold in the blowing device of the type that performs non-exhaust blow of FIGS. 4 to 6 described above.
[0038]
(First compressed air supply source, FIG. 7 to FIG. 9)
　The first compressed air supply source 21 in the blowing device 10 that exhausts air to the outside of the blow mold during cooling is activated by the high temperature arranged in the blow mold 8. A shaped object e in the form of a preform that can be shaped is inflated and brought into contact with the mold inner surface of the blow mold 8 (a hollow molded body shape forming surface) to send in compressed air of a pneumatic pressure capable of shaping. It is a thing. Even when the outflow passage 30 side is in the non-closed state (opening of the outflow passage), the preform swells so that the hollow molded body has an internal pressure that is appropriately shaped. The air pressure of the compressed air a for shaping is, for example, 1 MPa.
[0039]
(Second Compressed Air Supply Source, FIG. 7 to FIG. 9)
　The second compressed air supply source 22 in the blowing device 10 that exhausts air to the outside of the blow mold at the time of cooling is the object to be shaped e (hollow molded body). A large amount of air is ventilated from the internal space c to the outside of the blow mold, and compressed air having a pneumatic pressure that can efficiently cool the shaping target object e, which is the hollow molded body d, is sent from the internal space c side. Then, as will be described later, in the case where the outflow passage 30 side is in the non-closed state, the shaping target object e has an internal pressure that is appropriately cooled. The air pressure of the compressed air for this cooling is, for example, 3 MPa.
[0040]
(First Inflow Path)
　The electromagnetic valve 23 is interposed in the first inflow path 28, and in the shaping step, the electromagnetic valve 23 is opened to allow compressed air (1 MPa) from the first compressed air supply source 21. The shaped object (form of preform) e is blown into the internal space c.
[0041]
(Second Inflow Path)
　The second inflow path 29 is provided with a pressure reducing valve 20, a solenoid valve 23, and a check valve 24 from the upstream side of the flow of compressed air, and the solenoid valve 23 is opened in the cooling step. As a result, compressed air (3 MPa) from the second compressed air supply source 22 is blown into the internal space c of the shaping object e in the shape of the hollow molding.
[0042]
(Outflow Path) The
　outflow path 30 is a flow path for discharging the compressed air a that has entered the shaping object e (hollow molded body) to the outside of the blow mold as described above, and the solenoid valve 23 is interposed therebetween. .. In the shaping step, the solenoid valve 23 is closed, and in the cooling step, the solenoid valve 23 is opened.
[0043]
　As a result, in the blowing device 10, compressed air a having an air pressure of 1 MPa is blown from the first compressed air supply source 21 through the first inflow passage 28 and the outflow passage 30 is closed in the shaping step. The reform is inflated (shaped into a hollow molded body). See Figure 8
[0044]
　In the cooling stage, the first inflow passage 28 is closed, the second inflow passage 29 is opened, and the outflow passage 30 is also opened, so that the second compressed air supply source 22 passes through the second inflow passage 29. Compressed air a having an air pressure of 3 MPa, which is higher than the air pressure at the shaping stage, is blown, and is exhausted to the exhaust space outside the blow mold via the internal space c of the shaping target e (hollow molded body) and the outflow passage 30. Ventilation is performed as described above, and cooling is performed from the internal space side. See Figure 9
[0045]
　A silencer 25 is connected to the end portion of the outflow passage 30 in the same manner as the exhaust-side passage of the blowing device 10 in the non-exhaust blow type, and the compressed air a in the cooling stage passes through the silencer 25. Then, it is provided so as to flow out into the exhaust space.
[0046]
　In addition, in FIG. 8 and FIG. 9, the direction of the flow of compressed air is shown by the arrow. Further, in order to make the direction of the flow of the compressed air easy to see, the shaping object such as the preform or the hollow molded article is not shown. Further, in the figure, it is illustrated that the air tank 19 is connected to a pipeline of an operating system that uses compressed air for operations such as opening and closing of a core type, lifting and lowering of a blow core, and lifting and lowering of a rod.
[0047]
　However, in the blowing device that exhausts air outside the blow mold during cooling, a pipe line from the first compressed air supply source for the shaping stage and a pipe line from the second compressed air supply source for the cooling stage are provided. Since two separate pipelines are separately incorporated into the injection stretch blow molding machine, there is a problem that the structure of the entire injection stretch blow molding machine becomes complicated.
[0048]
　A compressor that stores compressed air in an air tank is a device that has the ability to generate compressed air with an air pressure of 3 MPa for the cooling stage. Then, there is a problem that a compressor such as a compressor that generates high-pressure compressed air becomes large in size, and power consumption also increases.
[0049]
　In the inventor of the present application, in producing a hollow molded article by the injection stretch blow molding machine, the outflow passage of the blowing device is opened in all blowing steps of the shaping step and the cooling step, and the shaping step is performed. An attempt was made to form a hollow molded article by performing a blowing operation of blowing compressed air having the same air pressure as the above air pressure.
[0050]
　Then, a blow molding operation is performed through the shaping step and the cooling step (exhaust to the outside of the core mold) to perform blow molding, and the outflow passage is opened during the entire blowing step of the blowing operation to perform compression. The blow molded product was blow-molded by blowing air into the hollow molded product. As a result, they have found that both hollow molded bodies are the same, and an appropriate hollow molded body can be obtained even when shaping and cooling are simultaneously performed during the entire blowing process.
[0051]
　Therefore, in view of the above circumstances, the present invention, when producing a hollow molded body with an injection stretch blow molding machine in which the molding cycle is shortened, blows compressed air for the shaping step of the preform and the inside of the hollow molded body. The shape and cooling are performed by blowing compressed air from one compressed air supply source while discharging the compressed air from the flow path end without distinguishing between blowing and blowing compressed air for cooling from the space side. It is an object of the present invention to carry out blow molding performed at the same time, and it is an object of the present invention to achieve energy saving for manufacturing a hollow molded body.
Means for solving the problem
[0052]
(Invention of Claim 1) The
　present invention has been made in consideration of the above-mentioned problems, and a shaped object in the form of a preform that can be shaped at a high temperature can be placed on the inner surface of the mold. A blow mold having a shape forming surface, a stretching device for advancing a rod toward the inside of a shaping object which is in the form of the preform arranged in the blow mold, and the preform. And a blowing device for blowing compressed air toward the inside of the object
to be shaped, and stretching to extend the object to be shaped in the form of the preform in the axial direction of the rod by the approach of the rod. A
blow operation consisting of a shaping operation in which the object to be shaped which is extended by the rod is expanded to expand the object to be shaped into a shape of a hollow molded article, and the internal space of the object to be shaped is cooled by ventilation. In the stretch blow molding apparatus to do, the
blowing device, a compressed air supply source for inflating the shaping object in the form of the preform and sending compressed air to the air pressure for shaping the shape of the hollow molded body, The inflow passage for the compressed air to flow from the compressed air supply source to the internal space of the shaping target disposed in the blow mold, and the exhaust space outside the blow mold from the internal space of the shaping target. A non-closed outflow passage through which compressed air flows out, and in
the entire process of the blow operation, the compressed air is passed from the compressed air supply source to the exhaust space through the inflow passage and the internal space of the object to be shaped. A compressed air flow path through which air flows is formed,
The compressed air channel is a preform shaped object that is in the form of a preform by inflating a shaped object in the form of a preform to blow compressed air at a pressure to shape the hollow molded body. The shaping by inflating the object into the shape of the hollow molded body and the cooling by ventilating the internal space of the shaping target are flow paths that are simultaneously performed in all steps of the blowing operation. It is intended to solve the above-mentioned problems by providing a stretch blow molding device characterized by being a thing.
[0053]
(Invention of Claim 2)
　Another aspect of the present invention is a blow in which a shaping object in the form of a preform that can be shaped at high temperature can be placed and a hollow molded body shape forming surface is provided on the inner surface of the mold. Mold, a stretching device for advancing a rod toward the inside of the object to be shaped in the form of the preform arranged in the blow mold, and the object to be shaped in the form of the preform. And a blowing device for blowing compressed air inward, and performing a
stretching operation of stretching the shaping object in the form of the preform in the axial direction of the rod by advancing the
rod, By a stretch blow molding device that performs a blowing operation that includes expanding the object to be shaped that is stretched with a shape of the object to be shaped into a hollow molded body and cooling the internal space of the object to be shaped by ventilation. In a blow molding method for making a shaping object in the form of a preform into a shaping object in the shape of a hollow molded body, the
blowing device is a shaping object in the form of the preform. A compressed air supply source that blows out compressed air by inflating and shaping the shape of the hollow molded body into air pressure, and from the compressed air supply source to the internal space of the shaping target object that is arranged in the blow mold. An inflow path through which compressed air flows, and an unclosed outflow path through which the compressed air flows from the internal space of the shaping object to the exhaust space outside the blow mold
, and in all steps of the blowing operation of the blowing device. Forming a compressed air flow path from the compressed air supply source through the inflow path and the internal space of the shaping object to the compressed air from the outflow path to the exhaust space,
Throughout all the steps of the blow operation, a preform is blown with compressed air having a pressure to inflate a shaped object in the form of a preform and shape the hollow molded body. A stretch blow molding method characterized in that the shaping and the cooling by ventilating the internal space of the shaping target are performed at the same time, in which the shaping target is inflated into a shape of a hollow molding. A blow molding method is provided to solve the above problems.
Effect of the invention
[0054]
　According to the present invention, compressed air flows from the compressed air supply source to the exhaust space through the inflow passage and the internal space of the shaping target object in all steps of the blowing operation of the blowing device in the stretch blow molding device. A compressed air flow path is formed, and a preform is formed in a state in which compressed air flows out of the compressed air flow path into the exhaust space outside the blow mold throughout the entire blow operation. The object to be shaped is inflated and compressed air having an air pressure for shaping the hollow molded article is blown into the object to be shaped and cooled at the same time.
[0055]
　In the production of hollow molded products using a conventional injection stretch blow molding machine, in order to make it possible to take out high-pressure compressed air from the air tank as the second compressed air supply source for the cooling stage, a large-sized compressed air is generated. However, in the present invention, the compressed air flows out of the compressed air flow path into the exhaust space outside the blow mold over the entire process of the blow operation as described above. , Blows compressed air with air pressure to inflate a shaping object in the form of a preform and shape it into a hollow molded body, so that compressed air for low pressure corresponding to the conventional shaping step is generated It is possible to manufacture a hollow molded body by using equipment, and it is possible to easily save energy for manufacturing the hollow molded body, which is an excellent effect.
Brief description of the drawings
[0056]
FIG. 1 is an explanatory view showing an injection stretch blow molding machine.
FIG. 2 is an explanatory view schematically showing the arrangement of an injection molding section, a stretch blow molding section, and a take-out section.
FIG. 3 is an explanatory view showing an example of a conventional stretch blow molding apparatus.
FIG. 4 is an explanatory view schematically showing a main part of a conventional stretch-blow molding device of a non-exhaust type during blowing.
FIG. 5 is an explanatory view schematically showing the flow of compressed air during low pressure blowing in a conventional stretch-blow molding apparatus of the type that is not exhausted during blowing.
FIG. 6 is an explanatory view schematically showing a flow of compressed air at the time of high-pressure blowing in a conventional stretch-blow molding device of a non-exhaust type during blowing.
FIG. 7 is an explanatory view schematically showing a main part of a conventional stretch-blow molding apparatus of a core exhaust type during cooling.
FIG. 8 is an explanatory view schematically showing a flow of compressed air in a shaping step of a conventional stretch-blow molding device of a type for exhausting outside core mold during cooling.
FIG. 9 is an explanatory view schematically showing a flow of compressed air in a cooling stage of a conventional stretch-blow molding apparatus of a core-exhaust type during cooling.
FIG. 10 is an explanatory view schematically showing an example of the stretch blow molding apparatus according to the present invention as viewed from the front side of the stretch blow molding section.
FIG. 11 is an explanatory view schematically showing a main part of the stretch blow molding apparatus according to the present invention.
FIG. 12 is an explanatory view schematically showing the flow of compressed air in the stretch blow molding method according to the present invention.
FIG. 13 is an explanatory view schematically showing another example of the flow of compressed air in the stretch blow molding method.
MODE FOR CARRYING OUT THE INVENTION
[0057]
　Next, the present invention will be described in detail based on the embodiment shown in FIGS. It should be noted that parts having the same configurations as those of the conventional example shown in FIGS. 1 to 9 are denoted by the same reference numerals and the description thereof will be omitted. The stretch blow molding apparatus 11 of the present invention is an apparatus configured in the stretch blow molding unit 4 of the injection stretch blow molding machine 1 as described above, and has the blow mold 8, the stretching apparatus 9 and the blowing apparatus 10. There is.
[0058]
　Then, the stretch blow molding apparatus 11 fits the blow core 15 into the lip mold 6 positioned corresponding to the blow mold 8, and the rod 12 is moved downward (downward in the axial direction of the rod) so as to pass through the internal core passage 14 of the blow core 15. ), and the inside of the shaping object e (which is in the form of a preform that can be shaped at high temperature) arranged inside the blow mold 8 while being supported by the lip mold 6. It is assumed that the stretching device 9 performs a stretching operation of advancing toward the object and stretching the shaping object e in the rod axial direction. See FIG. 10 and FIG.
[0059]
　Further, the stretch-blow molding apparatus 11 swells the object to be shaped which is stretched by the rod 12 in the stretching operation to shape the object to be shaped into a hollow molded article and the internal space of the object to be shaped. The blowing operation consisting of cooling by ventilation (cooling by ventilating compressed air to be blown) is performed by the blowing device 10. Unlike the above-described conventional example, in the present invention, shaping and cooling are performed. It is provided so that and can be performed at the same time.
[0060]
(
　Blow-In Device) The blow-in device 10 of the stretch blow molding device 11 of the present invention comprises a compressed air supply source 32 for taking out compressed air from the air tank 19, an inflow passage 33, and an outflow passage 34.
[0061]
(Compressed air supply source)
　The compressed air supply source 32 inflates the shaping object e, which is in the form of a preform that can be shaped at high temperature, to generate air pressure for shaping the hollow molding d. It sends out compressed air. The compressed air supply source 32 may be configured to inflate the object to be shaped e and send the compressed air a into the object to be shaped e having the shape of the hollow molded body d. As the above, it is possible to use a compressor such as a compressor having a capability of sending the compressed air taken out by the first compressed air supply source 21 in the conventional example described above to the air tank. The air pressure of the compressed air a sent from the compressed air supply source 32 is set to 1 MPa.
[0062]
(Inflow Path)
　The inflow path 33 is a flow path that allows the compressed air a to flow from the compressed air supply source 32 to the internal space c of the shaping object e in the mold of the blow mold 8. Specifically, an air supply pipe (not shown) whose one end is connected to the compressed air supply source 32 is connected to a portion of the blow core mounting body 16 that communicates with the in-core passage 14, so that the compressed air supply source 32 Compressed air a having an air pressure of 1 MPa is passed through the air supply pipe and the core internal passage 14, and the lower end of the blow core 15 is fitted into the lip mold 6 so that the rod 12 in the stretching device 9 is an object to be shaped. This is a flow path that allows the compressed air a to be blown inward of the object e to be shaped when the blow molding is performed inward of e.
[0063]
　As shown in FIG. 10, the portion of the air supply pipe that introduces the compressed air a into the core internal passage 14 is branched so as to correspond to the blow core, and each of the air supply pipes can be operated so as to move up and down. Is composed of a flexible tube 37.
[0064]
　In the inflow passage 33, a solenoid valve 23 is arranged in the middle of the flow passage as shown in FIG. 12 at a portion serving as an air supply pipe so that the inflow passage 33 is opened when the blowing device 10 performs a blowing operation. I have to.
[0065]
(Outflow Path)
　The outflow path 34 is a non-closed flow path that allows compressed air a to flow from the internal space c of the shaping object e to the exhaust space outside the blow mold. Specifically, an air supply pipe (not shown) is connected to a portion of the rod mounting body 13 that communicates with the in-rod passage 17, so that the compressed air pressure is 1 MPa from the internal space c of the shaping object e. a is formed so as to be flown out (exhausted) toward the exhaust space outside the blow mold, and the lower end of the blow core 15 fits into the lip mold 6 so that the rod 12 in the stretching device 9 is provided. This is a flow path for exhausting the compressed air a during the entire blow process when the blow molding is possible inside the shaped object e.
[0066]
　The portion of the air supply pipe connected to the rod internal passage 17 is also formed of a flexible tube 37 so that the air supply pipe can be moved up and down.
[0067]
　In the outflow passage 34, a throttle valve 35 is arranged at a portion serving as an air supply pipe as shown in FIG. 12, and a silencer 25 is arranged at an end portion thereof when the blowing device 10 is in a blowing operation. The flow path is always open regardless of whether or not the blow operation is stopped.
[0068]
(Compressed air flow path)
　In the blowing device 10 as described above, the compressed air supply source 32, the inflow path 33, and the shaping target object e (in the form of preform) are used in all steps of the blowing operation. A compressed air flow path 36 is formed through which the compressed air a flows from the outflow passage 34 to the exhaust space through the inner space c of the object to be shaped up to the shape of the hollow molded body).
[0069]
　Then, as shown in FIG. 12, in the compressed air flow path 36, the air pressure for expanding the shaping target object e and shaping it into the shape of the hollow molded body was set to 1 MPa throughout the entire process of the blowing operation. Since the compressed air a is exhausted from the outflow passage 34 on the downstream side in the feeding direction of the compressed air a, the stretch blow molding apparatus 11 performs all the steps of the blowing operation. By blowing the compressed air a into the object to be shaped e to inflate the object to be shaped e to form a hollow molded body and ventilating the internal space c of the object to be shaped e. It is provided so that cooling and cooling are performed simultaneously.
[0070]
　By arranging the throttle valve 35 in the outflow passage 34 as described above, the object to be shaped in the form of a preform that can be shaped at high temperature is made into the object to be shaped in the shape of the hollow molded body. I try to make the pressure more reliable.
[0071]
　In the inflow passage 33 in the above-described embodiment shown in FIGS. 11 and 12, the compressed air supply source 32 is configured as a portion from which the compressed air whose pressure has been adjusted by the pressure reducing valve 20 can be taken out. ing. Of course, when a desired air pressure can be taken out from the air tank 19, the compressed air supply source 32 can be a part of a structure which takes out the compressed air a directly from the air tank 19, as shown in FIG. ..
[0072]
　The compressed air having a pressure of 1 MPa is fed from the compressed air supply source 32, and the pressure for performing shaping to obtain the shape of the hollow molded body under the condition that the outflow passage 34 is opened is set to the shaping target object e. The means for surely obtaining the air while ventilating the internal space is not limited to using the throttle valve 35.
[0073]
　In addition, in order to inflate the shaping object e in the form of the preform b into the shaping object e in the shape of the hollow molded body d, in the above-described example, the compressed air taken out from the compressed air supply source 32 is used. Although the air pressure of a is set to 1 MPa, the air pressure of the compressed air is not limited to 1 MPa as long as it can be inflated to obtain an object to be shaped in the shape of the hollow molded body. For example, the compressed air delivered from the compressed air supply source 32 can have an air pressure selected from the range of 0.1 MPa to 3.5 MPa.
[0074]
(Comparison of Molded Articles) A
　conventional stretch blow molding apparatus was incorporated into an injection stretch blow molding machine to produce a hollow molded article, and the above-described present invention was carried out by incorporating a stretch blow molding apparatus as an example. A hollow molded body was manufactured. Then, the two hollow molded bodies produced were compared.
[0075]
　The blow operations of the conventional stretch blow molding apparatus and the stretch blow molding apparatus embodying the present invention were as follows. The hollow molded body was a PET milk bottle (for an internal capacity of 250 mL).
[0076]
(Conventional stretch blow molding device for comparison) As a
blowing operation, shaping (non-exhaust state) is performed in 1.9 seconds by feeding compressed air with an air pressure of 1 MPa, and then compressed air with an air pressure of 3 MPa is fed. Cooling (exhaust) by ventilation was performed in 2.3 seconds. The molding cycle of the injection stretch blow molding machine was set to 9.94 seconds.
[0077]
(Stretch Blow Molding Apparatus of Example for Comparison) As a
blowing operation, compressed air having an air pressure of 1 MPa is sent by constantly discharging air from the end portion (silencer portion) of the compressed air flow path, While performing shaping and cooling at the same time in 4.2 seconds, a hollow molded body was obtained. The molding cycle of the injection stretch blow molding machine was set to 9.96 seconds.
[0078]
　When the hollow molded article manufactured by incorporating the above-mentioned conventional stretch blow molding apparatus was compared with the hollow molded article produced by implementing the above-described present invention by incorporating the stretch blow molding apparatus of the example, both were obtained. It was confirmed that the hollow molded articles of No. 2 had the same molding dimensions, and that both hollow molded bodies were molded well.
[0079]
(Comparison of the flow rate of compressed air) When the flow rate of compressed air with a
　pressure of 3 MPa and the flow rate of compressed air with a pressure of 1 MPa, which are used in blow molding, are compared, the flow rate of compressed air with a
pressure of 3 MPa is blown. The maximum flow rate is about 10,000
L/min. The maximum flow rate is about 2,000 L/min when blowing compressed air with an air
pressure of 1 MPa. The maximum flow rate of 1 MPa is about 1/5 of the maximum flow rate of 3 MPa. there were.
[0080]
　The
minimum flow rate is about 4,000 L/min when blowing compressed air with an air pressure of 3 MPa,
and the minimum flow rate is about 1,000 L/min when blowing compressed air with an air
pressure of 1 MPa. Was about 1/4 of the minimum flow rate.
[0081]
　Comparing the maximum flow rate of the air pressure of 3 MPa and the minimum flow rate of the air pressure of 1 MPa, the minimum flow rate of the air pressure of 1 MPa is about 1/10 of the maximum flow rate of the air pressure of 3 MPa. Since the flow rate when the air pressure is 1 MPa is overwhelmingly small as described above, a case where a conventional stretch blow molding apparatus is incorporated into an injection stretch blow molding machine to manufacture a hollow molded article, and a stretch blow molding apparatus which is an example It can be seen that the amount of air used is smaller when the hollow molded article is manufactured by incorporating the above-mentioned method and when the hollow molded article is manufactured by carrying out the present invention.
[0082]
(Regarding the mold clamping unit in the stretch blow molding apparatus) In
　the example of the present embodiment in which compressed air having an air pressure of 1 MPa is blown to perform shaping and cooling at the same time, when the preform is deformed into the shape of the hollow molded body, Also, compressed air flows out from the compressed air flow path to the exhaust space, and the pressure to open the blow mold at this time is higher than the pressure to open the blow mold when shaping with conventional non-exhaust. Is getting smaller.
[0083]
　In particular, in the case of the conventional example, compressed air with an air pressure of 1 MPa is blown when shaping is performed without exhaust, and the pressure to open the blow mold at this time is small, but this embodiment In this case, even if compressed air having the same air pressure is blown in, the pressure for opening the blow mold becomes smaller. Therefore, as the mold clamping unit in the stretch blow molding apparatus, it is possible to employ a mold clamping unit having a small mold clamping force.
[0084]
　Further, in the case of a blow mold having a bottom mold, not only can the mold clamping force be reduced, but a pressure circuit that applies a small pressure for pushing up the bottom mold can also be adopted. Furthermore, the force with which the blow core resists the upward pressure during the blowing process can be small. Thus, it can be seen that the mold clamping force, the bottom mold pushing force, and the blow core pushing force can be reduced.
[0085]
　Further, since the mold clamping force, the bottom mold pushing-up force, the blow core pushing-down force, etc. applied to the blow mold can be reduced, it is possible to reduce the mold strength of the blow mold.
[0086]
　Further, it can be seen that the controllable electric circuit for opening and closing the first inflow path and the second inflow path in the above-described conventional device is not necessary, and the failure element can be reduced. Furthermore, in the present embodiment, the configuration is simplified, and the number of valve parts for controlling the flow of compressed air can be significantly reduced.
Explanation of symbols
[0087]
　1... Injection stretch blow molding machine
　4... Stretch blow molding part
　6... Lip mold
　8... Blow mold
　9... Stretching device
　10... Blowing device
　11... Stretch blow molding device
　12... Rod
　14... Core passage
　15... Blow core
　17... Inside rod Passage
　32... Compressed air supply source
　33... Inflow passage
　34... Outflow passage
　35... Throttle valve
　36... Compressed air flow path
　a... Compressed air
　b... Preform
　c... Internal space
　d... Hollow molded body
　e... Shaped object
The scope of the claims
[Claim 1]
A blow mold having a hollow molded body shape forming surface on the inner surface of the mold, which is capable of arranging an object to be shaped in the form of a preform capable of being shaped at high temperature, and a form of the preform arranged in the blow mold And a blowing device for injecting compressed air toward the inside of the object to be shaped in the form of the preform. The
object to be shaped, which is in the form of the preform, is stretched by advancing the rod in the axial direction of the rod, and the
object to be shaped that is stretched by the rod is inflated. In a stretch blow molding apparatus that performs a blowing operation that includes shaping an object into the shape of a hollow molded article and cooling the internal space of the object to be shaped by ventilation, the
blowing device is in the form of the preform. A compressed air supply source that inflates the shaping target object to form compressed air into air pressure for shaping into the shape of the hollow molded body, and a shaping target object arranged in the blow mold from the compressed air supply source. an inflow passage through which the compressed air in the interior space, have a outflow passage of the compressed air flows out non closed the blow mold out of the exhaust space from the interior space of the shaping object,
the entire process of the blowing operation At, a compressed air flow path is formed in which the compressed air flows from the compressed air supply source to the exhaust space through the inflow path and the internal space of the shaping target object,
The compressed air channel is a preform shaped object that is in the form of a preform by inflating a shaped object in the form of a preform to blow compressed air at a pressure to shape the hollow molded body. The shaping by inflating the object into the shape of the hollow molded body and the cooling by ventilating the internal space of the shaping target are flow paths that are simultaneously performed in all steps of the blowing operation. A stretch blow molding apparatus characterized by being a thing.
[Claim 2]
A blow mold having a hollow molded body shape forming surface on the inner surface of the mold, which is capable of arranging an object to be shaped in the form of a preform capable of being shaped at high temperature, and a form of the preform arranged in the blow mold And a blowing device for injecting compressed air toward the inside of the shaping target in the form of the preform. The
object to be shaped, which is in the form of the preform, is stretched by advancing the rod in the axial direction of the rod, and the
object to be shaped that is stretched by the rod is inflated. Hollow molding of an object to be shaped in the form of a preform by a stretch blow molding device that performs a blowing operation that includes shaping the object into the shape of a hollow molded article and cooling the internal space of the object to be shaped by ventilation. In a blow molding method for forming a shaped object having a body shape, the
blowing device inflates the shaped object that is in the form of the preform and uses air pressure to shape the shape of the hollow molded body. A compressed air supply source that sends out compressed air, an inflow passage through which the compressed air flows from the compressed air supply source to an internal space of the shaping target object arranged in the blow mold, and the inside of the shaping target object An unclosed outflow passage through which the compressed air flows out of the space to the exhaust space outside the blow mold, and in
the entire blow operation of the blowing device, the inflow passage from the compressed air supply source and the inside of the shaping object Forming a compressed air flow path through which the compressed air flows from the outflow passage to the exhaust space through the space,
Throughout all the steps of the blowing operation, a preform is blown with compressed air having an air pressure to inflate a shaped object in the form of a preform and shape the hollow molded body. A stretch blow molding method, wherein the shaping by expanding the shaping target into a shape of a hollow molded article and the cooling by ventilating the internal space of the shaping target are performed at the same time.