JP6411089B2 - Injection molding method, pressurized fluid introduction device and mold assembly - Google Patents

Description

  The present invention relates to an injection molding method, a pressurized fluid introduction device suitable for use in the injection molding method, and a mold assembly including the pressurized fluid introduction device.

  The molded product is required to be lightweight as a whole, depending on its shape. Also, the appearance is regarded as important, and there is no need for sink marks or warping. When molding such a molded product based on an injection molding method using a molten thermoplastic resin, it is added to the molten thermoplastic resin injected into the cavity in order to obtain a beautiful molded product having no sink marks or warpage. A method for injection molding of a molded article having a hollow portion, wherein a pressurized fluid is introduced to form a hollow portion inside the molten thermoplastic resin in the cavity, and the pressurized fluid in the hollow portion is released to the atmosphere before mold opening. Is widely used. As a result of the molten thermoplastic resin being pressed against the cavity surface of the mold by the pressurized fluid introduced into the molten thermoplastic resin injected into the cavity, it is possible to prevent the resulting molded product from sinking or warping. .

  By the way, in such a conventional injection molding method of a molded product having a hollow portion, the hollow portion formed inside the thermoplastic resin in the cavity is almost insulative. As a result, there is a problem that it takes a long time to cool and solidify the thermoplastic resin in the cavity.

  An injection molding method that solves this problem is well known, for example, from JP 2010-274515. In the technique disclosed in this patent publication, the mold assembly includes a cavity portion for molding the thickest part of the molded product along the flow direction of the molten thermoplastic resin injected into the cavity. The first pressurized fluid introduction part is arranged on the upstream side in the flow direction, and the second pressurized fluid introduction part is arranged on the downstream side in the flow direction. Then, after introducing the pressurized fluid through the first pressurized fluid introducing portion to form a hollow portion inside the molten thermoplastic resin in the cavity, the molten thermoplastic resin in the cavity is retained by the pressurized fluid. Apply pressure. Next, the introduction of the pressurized fluid through the first pressurized fluid introduction part into the hollow part is stopped, while the pressurized fluid is introduced into the hollow part through the second pressurized fluid introduction part.

JP 2010-274515

  In the technique disclosed in the above patent publication, introduction of the pressurized fluid into the hollow portion formed in the molten thermoplastic resin is performed by introducing the second pressurized fluid from the first pressurized fluid introducing portion. The thermoplastic resin in the cavity is cooled and solidified by the flow of pressurized fluid accompanying the switching. Therefore, it does not require a long time for cooling and solidifying the thermoplastic resin in the cavity. However, this state is maintained after the pressurized fluid is introduced into the hollow portion formed in the molten thermoplastic resin via the second pressurized fluid introducing portion. Therefore, there is room for improvement in cooling the thermoplastic resin in the cavity and further shortening the solidification time.

  Accordingly, an object of the present invention is to provide an injection molding method and an injection molding method that can cool and solidify a molten thermoplastic resin in a cavity in a shorter time when injection molding a molded article provided with a hollow portion. It is an object of the present invention to provide a pressurized fluid introducing device suitable for use in the above and a mold assembly including the pressurized fluid introducing device.

In order to achieve the above object, the injection molding method of the present invention comprises:
An injection molding method in which a molten thermoplastic resin is injected into a cavity provided in a mold, a pressurized fluid is introduced into the molten thermoplastic resin in the cavity, and a molded product having a hollow portion is formed,
Started injection of molten thermoplastic resin into the cavity,
During injection of the molten thermoplastic resin into the cavity, a pressurized fluid is introduced into the molten thermoplastic resin in the cavity simultaneously with or after the injection is completed, and a hollow portion is formed inside the molten thermoplastic resin. Forming, then
After cooling and solidifying the thermoplastic resin in the cavity with pressurized fluid,
Open the mold and take out the molded product.
It has each process,
In the process of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid in the hollow portion is measured, and the volumetric flow rate of the pressurized fluid introduced into the hollow portion and the outside of the system so that the desired pressure is obtained. And controlling the volume flow rate of the pressurized fluid discharged into the chamber.

In the injection molding method of the present invention,
A discharge hole communicating with the hollow part is formed in the molten thermoplastic resin,
A configuration can be adopted in which the pressurized fluid is discharged from the hollow portion to the outside of the system through the discharge hole. Here, in order to form the discharge hole communicating with the hollow portion in the molten thermoplastic resin, even if the discharge hole is formed in the molten thermoplastic resin by using a pressurized fluid discharge nozzle having a tip opened in the cavity. In addition, when a pressurized fluid is introduced into the molten thermoplastic resin in the cavity and a hollow portion is formed inside the molten thermoplastic resin, a part of the molten thermoplastic resin is blown off by the pressurized fluid, A discharge hole may be formed in the molten thermoplastic resin. However, it is not essential to form a discharge hole communicating with the hollow portion in the molten thermoplastic resin.

  In the injection molding method of the present invention including the above preferred form, the desired pressure may be a constant pressure. In this case, by controlling the difference between the volume flow rate of the pressurized fluid introduced into the hollow portion and the volume flow rate of the pressurized fluid discharged outside the system, the desired pressure is set to a constant pressure. Can do.

In order to achieve the above object, the pressurized fluid introduction apparatus of the present invention comprises:
A pressurized fluid introduction device for injecting a molten thermoplastic resin into a cavity provided in a mold and introducing a pressurized fluid into the molten thermoplastic resin in the cavity to form a molded product having a hollow portion. There,
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. It is characterized by controlling the volume flow rate.

In order to achieve the above object, a mold assembly of the present invention comprises:
(A) a first mold part;
(B) a second mold part,
(C) a cavity formed by clamping the first mold part and the second mold part,
(D) a molten resin injection part opened in the cavity, and
(E) a pressurized fluid introduction device for introducing a pressurized fluid into the molten thermoplastic resin injected into the cavity to form a molded article having a hollow portion;
With
Pressurized fluid introduction device
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. It is characterized by controlling the volume flow rate.

Pressurized fluid introduction device of the present invention, or pressurized fluid introduction device in the mold assembly of the present invention (hereinafter, these pressurized fluid introduction devices are collectively referred to as “pressurized fluid introduction device of the present invention”) In some cases)
The first proportional flow control valve is composed of a first diaphragm regulator,
The volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means can be controlled by the first diaphragm regulator based on the pressure measurement result of the pressure measuring means. And in this form,
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
The first diaphragm regulator can be driven by the electropneumatic regulator.

Furthermore, in the pressurized fluid introduction device of the present invention including the various preferred embodiments described above,
The second proportional flow control valve is composed of a second diaphragm regulator,
Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid discharged out of the system can be controlled by the second diaphragm regulator.

  Furthermore, in the pressurized fluid introduction apparatus of the present invention including the various preferred embodiments described above, the pressurized fluid discharge nozzle having a tip opened in the cavity is further provided, and the pressurized fluid in the hollow portion is It can be made the form discharged | emitted out of the system through a pressurized fluid discharge | emission nozzle and a 2nd proportional flow control valve. Further, in the pressurized fluid introduction device of the present invention including the various preferred embodiments described above, the cavity is a main cavity portion into which the molten thermoplastic resin is injected, and a waste communicated with the main cavity portion. It is comprised from the cavity part (overflow cavity part), The pressurized fluid in a hollow part can be made into the form discharged | emitted out of a system through a discard cavity part and a 2nd proportional flow control valve. In addition, it is preferable to provide a discarded cavity portion at the end in the flow direction of the molten thermoplastic resin injected into the cavity, preferably at the portion of the mold corresponding to the end, but this discarded cavity portion is provided. The part does not have to be a part corresponding exactly to the end in the flow direction of the molten thermoplastic resin.

  Furthermore, in the pressurized fluid introduction apparatus and the like of the present invention including the various preferred embodiments described above, the portion of the pressurized fluid flow path located between the first proportional flow control valve and the pressurized fluid introduction means Can be configured to have a pressurized fluid buffer storage device disposed therein. Alternatively, a third proportional flow control valve is provided between the pressurized fluid supply device and the pressurized fluid introduction means in parallel with the portion of the pressurized fluid flow path in which the first proportional flow control valve is disposed. In addition, a pressurized fluid flow path in which a pressurized fluid buffer storage device is disposed may be provided.

  Furthermore, in the pressurized fluid introduction apparatus and the like of the present invention including the various preferred embodiments described above, the pressurized fluid introduction means may be constituted by a pressurized fluid injection nozzle having a distal end portion opened in the cavity. it can.

Furthermore, in the pressurized fluid introduction device of the present invention including the various preferred embodiments described above,
The pressurized fluid consists of nitrogen gas,
The pressurized fluid supply device further includes: a pressurized fluid source that generates a pressurized fluid; an oil separator that removes oil in the pressurized fluid from the pressurized fluid source; and an oil in the pressurized fluid from the oil separator. It can be set as the form provided with the strainer to remove. And in this case
The strainer has a double pipe structure of an inner cylinder and an outer cylinder,
Inside the outer cylinder, there are provided a plurality of blades for generating a spiral flow in the pressurized fluid introduced into the outer cylinder from one end of the outer cylinder,
The inner cylinder includes a first oil removing layer made of felt, a second oil removing layer made of felt, and an activated carbon layer filled between the first oil removing layer and the second oil removing layer. In addition,
The pressurized fluid introduced into the outer cylinder from one end of the outer cylinder passes through the outer cylinder, is introduced into the inner cylinder, passes through the first oil removal layer, the activated carbon layer, and the second oil removal layer. Thus, it can be configured to be discharged from the inner cylinder.

  The first proportional flow rate control valve, the second proportional flow rate control valve, and the third proportional flow rate control valve can be constituted by a well-known proportional flow rate control valve, or the first diaphragm type regulator and the second diaphragm. The third diaphragm regulator that constitutes the third regulator and the third proportional flow rate control valve can also be constituted by a known diaphragm regulator. Further, the electropneumatic regulator can also be configured from a known electropneumatic regulator. Control of the operation of the electropneumatic regulator based on the pressure measurement result of the pressure measuring means, the driving of the first diaphragm type regulator, the second diaphragm type regulator, and the third diaphragm type regulator by the electropneumatic regulator are also known control and driving It can be. Furthermore, the pressure measuring means can also be constituted by a well-known pressure measuring means (pressure gauge or pressure sensor). Examples of the pressurized fluid source include a separation membrane type or PSA type nitrogen gas generator and a gas cylinder. Examples of the pressurized fluid buffer storage device include a kind of monitoring coil in which piping is wound in a coil shape, and a buffer tank.

  In the pressurized fluid introduction apparatus and the like of the present invention including the preferred embodiments described above, the pressurized fluid injection nozzle and the pressurized fluid discharge nozzle may be constituted by a known pressurized fluid injection nozzle and a pressurized fluid discharge nozzle. . A configuration in which heating means (for example, an electric heater) for heating a portion of a pressurized fluid injection nozzle or a pressurized fluid discharge nozzle in contact with the molten thermoplastic resin is provided in the pressurized fluid injection nozzle or the pressurized fluid discharge nozzle; can do. By arranging the heating means in this way, it is possible to avoid the start of instantaneous solidification of the molten thermoplastic resin in the vicinity of the pressurized fluid injection nozzle and the pressurized fluid discharge nozzle, and the inside of the cavity through the pressurized fluid injection nozzle. The pressurized fluid can be reliably introduced into the molten thermoplastic resin, and the pressurized fluid in the hollow portion can be reliably discharged out of the system via the pressurized fluid discharge nozzle.

  In the pressurized fluid introduction device of the present invention including the preferred configuration described above, the pressurized fluid introduction means (pressurized fluid injection nozzle) and the pressurized fluid discharge nozzle are arranged in the first mold part. It may be provided, may be disposed on the second mold part, or may be disposed on the first mold part and the second mold part. As an example of the arrangement of the pressurized fluid introducing means to the mold assembly, the pressurized fluid introducing means is arranged so that the tip of the pressurized fluid introducing means is disposed in the cavity or in the vicinity of the cavity surface of the mold. It can be set as the structure arrange | positioned in one metal mold | die part, a 2nd metal mold | die part, or a 1st metal mold | die part and a 2nd metal mold | die part. The pressurized fluid introducing means can be, for example, a known pressurized fluid injection nozzle having a check valve disposed at the tip. If necessary, a heating means (for example, an electric heater) for heating the tip may be attached as described above. In some cases, the pressurized fluid introducing means may be disposed such that the tip portion is disposed in the molten resin injection portion, or the tip portion is the tip portion (nozzle of the injection cylinder). May be disposed so as to be disposed in the resin flow path connecting the injection cylinder and the molten resin injection portion.

  In carrying out the injection molding method of the present invention, the amount of molten thermoplastic resin at the time of injection molding, temperature, pressure or injection speed, the amount of pressurized fluid to be introduced to form the hollow part, pressure or speed, gold Various conditions such as the mold cooling time need to be appropriately selected and controlled depending on the type of thermoplastic resin used, the shape of the mold, etc., and cannot be uniquely determined.

  Examples of the molded product obtained by the injection molding method of the present invention include a handle-formed product, a long molded product, or a thin molded product that partially has a thick portion. Here, the handle-formed product is a unit in which a thick grip part and at least one attachment part are integrated, and the grip part corresponds to the thickest part of the molded product, and the thickest part concerned. The (grip part) is provided with a hollow structure. The molded product is attached to an automobile, an electrical appliance, a door of a building, or the like at the attachment portion. And a user grasps a grip part and opens and closes a door etc. The molded article usually has a handle or lever shape. On the other hand, as long molded products, roof rails and various pipes that can be attached to the roof of automobiles can be cited, and as thin molded products that have partially thick parts, outer panels such as bonnets and various covers are listed. be able to. However, the molded product is not limited to these.

  The pressurized fluid introduction device of the present invention including the preferred embodiment and configuration described above, the mold assembly of the present invention, or the injection molding method of the present invention including the preferred embodiment described above (hereinafter collectively referred to as these). In some cases, the amount of molten thermoplastic resin to be injected into the cavity is preferably an amount that does not completely fill the cavity (short shot method). However, the present invention is not limited to this, and the amount of the molten thermoplastic resin to be injected into the cavity may be an amount that completely fills the cavity (full shot method). In the case of providing the waste cavity portion, the amount of the molten thermoplastic resin to be injected into the cavity may be an amount that does not completely fill the cavity, or the cavity is completely filled. The amount may not be completely filled. The structure of the mold assembly may be a single molded product or a multiple product.

  The pressurized fluid is a gas substance at normal temperature and normal pressure, and preferably does not react or mix with the thermoplastic resin used. Specifically, in addition to the nitrogen gas described above, air, carbon dioxide gas, helium gas, and the like can be given. In consideration of safety and economy, nitrogen gas and helium gas are preferable. A gas liquefied under high pressure may also be included.

  The first mold part and the second mold part can be made of a known metal material such as carbon steel, stainless steel, aluminum alloy, copper alloy or the like.

  The structure of the molten resin injection part (specifically, the gate part) can be any known gate structure, for example, a direct gate structure, a side gate structure, a jump gate structure, a pinpoint gate structure, a tunnel. Examples thereof include a gate structure, a ring gate structure, a fan gate structure, a disk gate structure, a flash gate structure, a tab gate structure, and a film gate structure.

  Examples of the thermoplastic resin suitable for use in the present invention include a crystalline thermoplastic resin and an amorphous thermoplastic resin. Specifically, polyolefin resins such as polyethylene resin and polypropylene resin; polyamide 6, Polyamide resins such as polyamide 66 and polyamide MXD6; Polyoxymethylene (polyacetal, POM) resin; Polyester resins such as polyethylene terephthalate (PET) resin and polybutylene terephthalate (PBT) resin; Polyphenylene sulfide resin; Polystyrene resin, ABS resin Styrene resin such as AES resin, AS resin, methacrylic resin, polycarbonate resin, modified polyphenylene ether (PPE) resin, polysulfone resin, polyethersulfone resin, polyarylate resin, polyether resin De resin; polyamideimide resin; polyimide resins; polyether ketone resins; polyether ether ketone resin; can be illustrated a liquid crystal polymer; polyester carbonate resin.

  Furthermore, a thermoplastic resin made of a polymer alloy material can be used. Here, the polymer alloy material is composed of a blend of at least two types of thermoplastic resins, or a block copolymer or graft copolymer in which at least two types of thermoplastic resins are chemically bonded. A polymer alloy material is widely used as a high-functional material that can have the unique performance of each of the individual thermoplastic resins. As a thermoplastic resin constituting a polymer alloy material in which at least two kinds of thermoplastic resins are blended, styrene resins such as polystyrene resin, ABS resin, AES resin, and AS resin; polyolefin resins such as polyethylene resin and polypropylene resin; methacrylic resin Polycarbonate resin; polyamide resin such as polyamide 6, polyamide 66, polyamide MXD6; modified PPE resin; polyester resin such as polybutylene terephthalate resin and polyethylene terephthalate resin; polyoxymethylene resin; polysulfone resin; polyimide resin; Polyarylate resin; Polyether sulfone resin; Polyether ketone resin; Polyether ether ketone resin; Polyester carbonate resin Can. As a polymer alloy material obtained by blending two types of thermoplastic resins, a polymer alloy material of a polycarbonate resin and an ABS resin can be exemplified. Such a combination of resins is expressed as polycarbonate resin / ABS resin. The same applies to the following. Furthermore, as a polymer alloy material blended with at least two types of thermoplastic resins, polycarbonate resin / PET resin, polycarbonate resin / PBT resin, polycarbonate resin / polyamide resin, polycarbonate resin / PBT resin / PET resin, modified PPE resin / HIPS Examples thereof include resin, modified PPE resin / polyamide resin, modified PPE resin / PBT resin / PET resin, modified PPE resin / polyamide MXD6 resin, polyoxymethylene resin / polyurethane resin, and PBT resin / PET resin.

  In addition, an additive, a filler, and a reinforcing agent can also be added to the various thermoplastic resins described above.

  Additives: Plasticizers; Stabilizers; Antioxidants: Ultraviolet absorbers; Ultraviolet stabilizers such as organic nickel compounds such as nickel bis (octylphenyl) sulfide, hindered amine compounds; Antistatic agents; Flame retardants; Vinadin, Priben Antifungal agents such as Thor and Thiabendazole; Lubricants such as liquid paraffin, polyethylene wax and fatty acid amide; Organic foaming agents such as ADCA; Transparent coloring agents; Various colorants such as organic pigments and inorganic pigments; Crosslinking agents; Acrylic graft polymers, Mention may be made of impact-strengthening agents such as MBS.

  Plasticizers such as diethyl phthalate, di-n-butyl phthalate, 2-ethylhexyl phthalate, diisononyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate; triethyl phosphate, tributyl phosphate, phosphoric acid Phosphate esters such as tricresyl, triphenyl phosphate; fatty acid base esters such as butyl oleate, dibutyl adipate, adipic acid-n-hexyne, di-2-ethylhexyl adipate; alcohol esters such as diethylene glycol dibenzoate Oxyacid esters such as acetyltriethyl citrate and dibutyl maleate; trimellitic plasticizer; polyester plasticizer; epoxy plasticizer; chlorinated paraffinic plasticizer.

  As stabilizers, organotin stabilizers such as di-n-octyltin compounds, di-n-butyltin compounds, and dimethyltin compounds; lead compound systems such as tribasic lead sulfate, dibasic lead phosphite, and lead silicate Stabilizers; metal soap-based stabilizers such as cadmium soap, lead soap, zinc soap; trisnonyl phosphate; trisnonylphenyl phosphate;

  As antioxidants, phenolic antioxidants such as dibutylcresol and butylhydroxyanisole; bisphenolic antioxidants such as methylenebis (methylbutylphenol) and thiobis (methylbutylphenol); tris (methylhydroxybutylphenyl) butane, tocophenol, etc. And polyphosphoric antioxidants; organic sulfur compounds such as dimyristylthiodipropionate; and organic phosphorus compounds such as tris (mono / dinonylphenyl) phosphite.

As UV absorbers, salicylic acid UV absorbers such as phenyl salicylate and butylphenyl salicylate; benzophenone UV absorbers such as dihydroxybenzophenone; benzotriazole UV absorbers such as (hydroxymethylphenyl) benzotriazole; ethylhexylcyanodiacrylate Examples include cyanoacrylate-based ultraviolet absorbers such as phenonyl.
Antistatic agents such as poly (oxyethylene) alkylamines, poly (oxyethylene) alkylphenyl ethers, and other nonionic surfactant antistatic agents; alkylsulfonates, alkylbenzenesulfonates, alkylphosphates, etc. Examples include ionic surfactant-based antistatic agents; cationic surfactant-based antistatic agents such as quaternary ammonium chloride; amphoteric surfactants; and conductive resins.

  As flame retardants, halogen flame retardants such as tetrabromobisphenol A, polybromobiphenol, bis (hydroxydibromophenyl) propane, chlorinated paraffin; phosphorus flame retardants such as ammonium phosphate and tricresyl phosphate; antimony trioxide; red phosphorus ; Tin oxide etc. can be mentioned.

  As fillers and reinforcing agents, inorganic materials: stainless steel fibers, high-strength amorphous metal fibers, stainless steel foils, steel foils, copper foils and other metal materials; high-molecular polyethylene fibers, high-strength polyarate fibers, para-type all Examples include organic materials such as aromatic polyamide fibers, aramid fibers, PEEK fibers, PEI fibers, PPS fibers, fluororesin fibers, phenol resin fibers, vinylon fibers, polyacetal fibers, and powder materials.

  Here, as inorganic fillers and reinforcing agents, glass-based materials such as glass fibers, long glass fibers, and quartz glass fibers; carbon-based materials such as PAN-based carbon fibers, pitch-based carbon fibers, and graphite whiskers; silicon carbide fibers , Silicon carbide continuous fiber, silicon carbide whisker, silicon carbide whisker sheet, etc .; boron carbide material such as boron fiber; Si—Ti—C—O material such as Si—Ti—C—O fiber; potassium titanate Examples thereof include potassium titanate materials such as fibers, potassium titanate whiskers and potassium titanate conductive whiskers; silicon nitride materials such as silicon nitride whiskers and silicon nitride whisker sheets; and calcium sulfate materials such as calcium sulfate whiskers. .

  In addition, as powder-based fillers and reinforcing agents, mica flakes, mica powder, shirasu balloon, silica powder, talc powder, aluminum hydroxide powder, magnesium hydroxide powder, magnesium silicate powder, calcium sulfate powder, spherical hollow glass powder, Metallized powder, high purity synthetic silica powder, tungsten disulfide powder, tungsten carbide powder, zirconia powder, zirconia powder, partially stabilized zirconia powder, alumina-zirconia composite powder, composite metal powder, iron powder, aluminum powder, molybdenum Examples thereof include metal powder, tungsten powder, aluminum nitride powder, nylon fine particle powder, silicone resin powder, spinel powder, amorphous alloy powder, aluminum flake, and glass flake.

  In the injection molding method of the present invention, in the step of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid in the hollow portion is measured and introduced into the hollow portion so as to obtain a desired pressure. The volume flow rate of the pressurized fluid and the volume flow rate of the pressurized fluid discharged out of the system are controlled. Therefore, as a result of a kind of flow occurring in the pressurized fluid in the hollow portion, the thermoplastic resin in the cavity can be cooled and solidified in a shorter time. Moreover, in the step of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid introduced into the thermoplastic resin in the cavity is controlled to be a desired pressure, so that the molten thermoplastic resin is made of gold. As a result of being appropriately pressed against the cavity surface of the mold, it is possible to more reliably prevent the occurrence of sink marks and warpage in the obtained molded product, and stable injection molding of the molded product can be performed. The shape accuracy can be improved. Furthermore, since the volume flow rate of the pressurized fluid introduced into the hollow portion and the volume flow rate of the pressurized fluid discharged outside the system are controlled, the pressure change profile of the pressurized fluid introduced into the thermoplastic resin in the cavity is controlled. The degree of freedom of control is increased, and a more stable molded product can be injection molded, and the shape accuracy of the molded product can be further improved.

FIG. 1 is a conceptual diagram of a mold assembly according to a first embodiment including a pressurized fluid introducing device. 2A, 2 </ b> B, and 2 </ b> C are schematic end views of a mold and the like for explaining the injection molding method in the first embodiment. FIG. 3 is a diagram schematically illustrating a change in pressure in the hollow portion and a change in volume flow rate of the pressurized fluid when the injection molding is performed in the first embodiment. FIG. 4 is a conceptual diagram of a mold assembly of Example 2 including a pressurized fluid introduction device. 5A and 5B are schematic end views of a mold or the like for explaining the injection molding method in the second embodiment, and FIG. 5C is a diagram for explaining the injection molding method in the modification of the second embodiment. It is a typical end view of a mold or the like. FIG. 6 is a conceptual diagram of a mold assembly of Example 3 including a pressurized fluid introduction device. FIG. 7 is a conceptual diagram of a modified example of the mold assembly according to the third embodiment including the pressurized fluid introduction device. FIG. 8 is a conceptual diagram of a mold assembly of Example 4 including a pressurized fluid introduction device. FIG. 9 is a conceptual diagram (schematic diagram) of a pressurized fluid supply device according to the fifth embodiment.

  Hereinafter, the present invention will be described based on examples with reference to the drawings. However, the present invention is not limited to the examples, and various numerical values and materials in the examples are examples.

  Example 1 relates to an injection molding method, a pressurized fluid introduction device, and a mold assembly of the present invention. A conceptual diagram of a mold assembly of Example 1 including a pressurized fluid introducing device is shown in FIG. 1, and a schematic end view of a mold or the like for explaining an injection molding method in Example 1 is shown in FIGS. Shown in 2B and 2C. Further, FIG. 3 schematically shows a change in pressure in the hollow portion and a change in volume flow rate of the pressurized fluid.

  Specifically, the molded product obtained by the injection molding method of Example 1 is a handle-formed product. Here, the handle-formed product is a unit in which a thick grip part and at least one attachment part are integrated, and the grip part corresponds to the thickest part of the molded product, and the thickest part concerned. The (grip part) is provided with a hollow structure. The handle-shaped product is attached to an automobile, an electrical appliance, a door of a building, or the like at the attachment portion. And a user grasps a grip part and opens and closes a door etc. The handle forming product has a handle shape.

The mold assembly 10 of Example 1 is
(A) first mold part (fixed mold part) 11,
(B) second mold part (movable mold part) 12,
(C) a cavity 14 formed by clamping the first mold part 11 and the second mold part 12;
(D) Molten resin injection part 13 opened in cavity 14, and
(E) a pressurized fluid introducing device 20 for introducing a pressurized fluid into the molten thermoplastic resin 16 injected into the cavity 14 to form a molded article having the hollow portion 17;
It has.

The pressurized fluid introduction device 20
(A) Pressurized fluid supply device 30,
(B) Pressurized fluid introduction means 41 for introducing a pressurized fluid into the molten thermoplastic resin 16 in the cavity 14;
(C) a first proportional flow rate control valve 51 disposed in a portion 61 of the pressurized fluid flow path located between the pressurized fluid supply device 30 and the pressurized fluid introducing means 41;
(D) a second proportional flow control valve 52 disposed in a portion 63 of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion 17 out of the system, and
(E) a pressure measuring means 54 disposed in a portion 62 of the pressurized fluid flow path located between the first proportional flow control valve 51 and the second proportional flow control valve 52;
It is composed of And
The pressure measuring means 54 measures the pressure of the pressurized fluid in the hollow portion 17,
The first proportional flow control valve 51 controls the volume flow V ₁ of the pressurized fluid flowing into the hollow portion 17 so that the desired pressure is obtained, and the second proportional flow control valve 52 is discharged out of the system. The volume flow rate V ₂ of the pressurized fluid to be controlled is controlled.

The first proportional flow control valve 51 is composed of a first diaphragm regulator. The first diaphragm regulator is a diaphragm regulator having a known configuration and structure. Then, based on the pressure measurement result of the pressure measuring means 54, pressurization supplied from the pressurized fluid supply device 30 to the pressurized fluid introducing means 41 by the first proportional flow control valve (first diaphragm regulator) 51. The volume flow rate V _{1 of the} fluid is controlled. The pressurized fluid introduction device 20 further includes an electropneumatic regulator 55 having a well-known configuration and structure, and the operation of the electropneumatic regulator 55 is controlled based on the pressure measurement result of the pressure measuring means 54, and the electropneumatic regulator 55. Accordingly, the first proportional flow control valve (first diaphragm regulator) 51 is driven, and the second proportional flow control valve (second diaphragm regulator) 52 described below is also driven.

The second proportional flow control valve 52 is composed of a second diaphragm regulator, and based on the pressure measurement result of the pressure measuring means 54, the second proportional flow control valve (second diaphragm regulator) 52 is used. The volume flow rate V ₂ of the pressurized fluid discharged out of the system is controlled. The second diaphragm regulator is a diaphragm regulator having a known configuration and structure. Further, the cavity 14 is provided with a pressurized fluid discharge nozzle 42 having an open end, and the pressurized fluid in the hollow portion 17 passes through the pressurized fluid discharge nozzle 42 and the second proportional flow control valve 52. And discharged outside the system.

  The pressurized fluid introducing means 41 is composed of a pressurized fluid injection nozzle whose tip is open to the cavity 14. As shown in the conceptual diagram of FIG. 1, the pressurized fluid introducing means 41 (more specifically, the rear end portion of the pressurized fluid injection nozzle) is provided with piping that constitutes the pressurized fluid channels 61 and 62. To the pressurized fluid supply device 30. That is, the first proportional flow control valve 51 and the pressure measuring means 54 are arranged in the middle of the pipe from the pressurized fluid supply device side. The rear end portion of the pressurized fluid discharge nozzle 42 communicates with the outside of the system through a pipe constituting the pressurized fluid channel 63. That is, the second proportional flow rate control valve 52 is arranged in the middle of this pipe. The pressure measuring means 54 may be disposed anywhere as long as it is a portion of the pressurized fluid channel located between the first proportional flow control valve 51 and the second proportional flow control valve 52.

  In the first embodiment, more specifically, the molten resin injection portion 13 has a side gate structure opened to the cavity 14. The molten resin injection part 13 communicates with an injection cylinder (not shown) via a resin flow path 13A. The pressurized fluid is composed of nitrogen gas, and the pressurized fluid source 31 (see FIG. 9) in the pressurized fluid supply device 30 is constituted by, for example, a PSA-type nitrogen gas generator. The distal ends of the pressurized fluid introducing means (pressurized fluid injection nozzle) 41 and the pressurized fluid discharge nozzle 42 are disposed so as to be disposed in the cavity 14. Each of the pressurized fluid introducing means 41 and the pressurized fluid discharge nozzle 42 is provided with a hydraulic cylinder (not shown). By the operation of the hydraulic cylinder, the pressurized fluid introducing means 41 and the pressurized fluid discharge nozzle 42 are provided. Are located at the forward and backward positions. When in the advanced position, the respective tip portions of the pressurized fluid introducing means 41 and the pressurized fluid discharge nozzle 42 are located in the cavity 14. When in the retracted position, the respective tip portions of the pressurized fluid introducing means 41 and the pressurized fluid discharge nozzle 42 are positioned in the same plane as the cavity surface of the mold (specifically, the second mold section 12). To do.

  2A, 2B and 2C, and FIG. 3, the molten thermoplastic resin 16 is injected into the cavity 14 provided in the mold, and the molten thermoplastic resin 16 in the cavity 14 is injected. The injection molding method of Example 1 in which a pressurized fluid is introduced to form a molded product having the hollow portion 17 will be described. In Example 1, polycarbonate resin (trade name: Iupilon S-3000) manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used as the thermoplastic resin, and the injection conditions were as shown in Table 1 below.

[Table 1]
Molten resin temperature: 280 ° C
Mold temperature: 80 ° C
Injection time: 6 seconds

[Step-100]
First, the molten thermoplastic resin 16 is injected into the cavity 14 via the molten resin injection portion 13. Specifically, the first mold part 11 and the second mold part 12 are clamped (see FIG. 1). After the thermoplastic resin 16 is plasticized, melted and measured in an injection cylinder (not shown), the molten thermoplastic resin 16 is injected from the injection cylinder into the cavity 14 through the resin flow path 13A and the molten resin injection portion 13. (See FIG. 2A). The volume of the cavity 14 was 96 cm ³ , and the volume of the molten thermoplastic resin 16 injected into the cavity 14 was 65 cm ³ . Here, the first proportional flow control valve 51 and the second proportional flow control valve 52 are closed, and the operation of the electropneumatic regulator 55 is also stopped. Further, the pressurized fluid introducing means (pressurized fluid injection nozzle) 41 and the pressurized fluid discharge nozzle 42 are located in the retracted position.

[Step-110]
Next, during the injection of the molten thermoplastic resin 16, simultaneously with the completion of the injection or after the completion of the injection, a pressurized fluid is introduced into the molten thermoplastic resin 16 in the cavity 14, and a hollow portion is formed inside the molten thermoplastic resin 16. 17 is formed. Specifically, a hydraulic cylinder (not shown) constituting the pressurized fluid introducing means (pressurized fluid injection nozzle) 41 is operated to be positioned at the forward movement position. Then, introduction of the pressurized fluid into the molten thermoplastic resin 16 in the cavity 14 via the pressurized fluid introducing means 41 is started (see time t ₀ in FIG. 3), and the inside of the molten thermoplastic resin 16 in the cavity 14 is started. The hollow portion 17 is formed (see time t ₀ to time t ₁ in FIG. 2B and FIG. 3). Specifically, in Example 1, the first proportional flow control valve 51 was opened simultaneously with the completion of the injection of the molten thermoplastic resin 16. The second proportional flow control valve 52 remains closed.

The pressure in the hollow part 17 measured by the pressure measuring means 54 is from the gauge pressure “0” Pa (time t ₀ ) before the hollow part 17 is formed to the time t ₁ when the formation of the hollow part 17 is completed. It increases to gauge pressure P _1. In the example illustrated in FIG. 3, the pressure in the hollow portion 17 increases linearly, but is not limited to such an increased state. In this step, since the second proportional flow control valve 52 remains closed, the value of the volume flow rate V ₂ is “0” and the value of V ₂ / V ₁ is also “0”. is there.

[Step-120]
And the discharge hole connected to the hollow part 17 is formed in the molten thermoplastic resin 16, and pressurized fluid is discharged | emitted out of the system through a discharge hole from the hollow part 17 (refer FIG. 2C). Specifically, first, with the first proportional flow control valve 51 open, a hydraulic cylinder (not shown) constituting the pressurized fluid discharge nozzle 42 is operated to advance the pressurized fluid discharge nozzle 42 forward. To position. As a result, a discharge hole communicating with the hollow portion 17 can be formed in the molten thermoplastic resin 16. The tip of the pressurized fluid discharge nozzle 42 is located in the hollow portion 17. Then, the second proportional flow control valve 52 is opened (see time t ₁ in FIG. 3). The volume flow rate of the second proportional flow rate control valve 52 was V ₂ (= V ₁ ). Then, the operation of the electropneumatic regulator 55 is started. By maintaining the volume flow rates V ₁ and V ₂ while the first proportional flow rate control valve 51 and the second proportional flow rate control valve 52 are kept open from time t ₁ to time t ₂ , the pressure P ₁ Hold. As a result of appropriately pressing the molten thermoplastic resin 16 in the cavity 14 against the cavity surface of the mold, it is possible to prevent sink marks and warpage from occurring in the obtained molded product. When the pressure in the hollow portion 17 measured by the pressure measuring unit 54 varies from the set pressure P ₁ , the operation of the electropneumatic regulator 55 is controlled based on the measurement result of the pressure measuring unit 54. The first proportional flow control valve 51 and / or the second proportional flow control valve 52 are driven, and the pressure in the hollow portion 17 is maintained at the set pressure P ₁ .

[Step-130]
Next, the thermoplastic resin 16 in the cavity 14 is cooled and solidified by the pressurized fluid. At this time, the pressure of the pressurized fluid in the hollow portion 17 as measured by the pressure measuring means 54, to a desired pressure P _0, specifically, the desired pressure P ₀ is a constant pressure As described above, the volume flow rate V ₁ of the pressurized fluid introduced into the hollow portion 17 and the volume flow rate V ₂ of the pressurized fluid discharged outside the system are controlled. That is, by controlling the difference between the volume flow rate V ₁ of the pressurized fluid introduced into the hollow portion 17 and the volume flow rate V ₂ of the pressurized fluid discharged out of the system, the desired pressure P ₀ is made constant. . Specifically, when the shape of the hollow portion 17 begins to stabilize (see time t ₂ in FIG. 3), for example, to change the set pressure of the hollow portion 17 to P ₀ (<P _1). Then, the operation of the electropneumatic regulator 55 is controlled based on the measurement result of the pressure measuring means 54, and the first proportional flow rate control valve 51 and the second proportional flow rate control valve 52 are driven by the electropneumatic regulator 55, and the hollow portion 17. The internal pressure changes toward the set pressure P ₀ . Specifically, for example, if the volume flow rate in the second proportional flow rate control valve 52 remains V ₂ , the volume flow rate in the first proportional flow rate control valve 51 once becomes V ₁ ′ (<V ₁ = V ₂₎ to become. V ₂ / V ₁ ′> 1. As a result, the volume flow rate of the pressurized fluid discharged from the hollow portion 17 is larger than the volume flow rate of the pressurized fluid supplied to the hollow portion 17, and as a result, the pressure in the hollow portion 17 is changed from P ₁ to P _0. Decline toward The operation of the electropneumatic regulator 55 is controlled based on the measurement result of the pressure measuring means 54, the first proportional flow rate control valve 51 is driven by the electropneumatic regulator 55, and the volume flow rate is from V ₁ ′ (<V ₁ ). It increases to V _1. Then, when the measurement result of the pressure measuring means 54 becomes P ₀ (see time t _{3 in} FIG. 3), the volume flow rate in the first proportional flow rate control valve 51 and the volume flow rate in the second proportional flow rate control valve 52. Becomes V ₁ and V ₂ (= V ₁ ), and the pressure in the hollow portion 17 is maintained at the set pressure P ₀ . Incidentally, the set pressure in the hollow portion 17 was changed to P ₀ (<P _1), and may change the value of V ₂ to V ₂ "(≠ V _2). Then, the state, the time Continues to t _{4. When the} pressure in the hollow portion 17 measured by the pressure measuring means 54 fluctuates from the set pressure P ₀ , the operation of the electropneumatic regulator 55 is controlled based on the measurement result of the pressure measuring means 54. first proportional flow control valve 51 and the second proportional flow control valve 52 is driven by the electropneumatic regulator 55, the pressure in the hollow portion 17 is maintained at the set pressure P _0.

[Step-140]
After the time t ₄ has elapsed, the operation of the electropneumatic regulator 55 is stopped, and the first proportional flow control valve 51 is closed. The second proportional flow control valve 52 remains open. As a result, the pressurized fluid in the hollow portion 17 is discharged out of the system via the pressurized fluid discharge nozzle 42 and the second proportional flow rate control valve 52. Thereafter, the pressurized fluid injection nozzle 41 and the pressurized fluid discharge nozzle 42 are positioned at the retracted position, the mold is opened, and the molded product is taken out. Thus, a molded product having the hollow portion 17 can be obtained.

  In the obtained molded product (handle-formed product), neither sink nor warp was observed, and a desired hollow portion 17 was formed inside.

  For comparison, the same process as [Process-110] was continued as it was, and the introduction of the pressurized fluid from the pressurized fluid supply device 30 via the pressurized fluid introducing means 41 was continued. In other words, the pressurized fluid introducing means (pressurized fluid injection nozzle) 41 was left open, and the pressurized fluid discharge nozzle 42 was left closed. Then, after the thermoplastic resin 16 in the cavity 14 was cooled and solidified, the pressurized fluid in the hollow portion 17 was discharged out of the system through the pressurized fluid introduction means (pressurized fluid injection nozzle) 41. The time required for cooling and solidifying the thermoplastic resin 16 in the cavity 14 was six times that in Example 1.

In the injection molding method of Example 1, in the step of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid in the hollow portion is measured, and the hollow portion is adjusted so that the desired pressure P ₀ is obtained. The volume flow rate V ₁ of the pressurized fluid introduced into the system and the volume flow rate V ₂ of the pressurized fluid discharged out of the system are controlled. Therefore, a flow of pressurized fluid is formed in the hollow portion, and the thermoplastic resin in the cavity can be cooled and solidified in a shorter time. Moreover, in the step of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid introduced into the thermoplastic resin in the cavity is controlled to be a desired pressure P ₀ , so that the molten thermoplastic resin As a result of being appropriately pressed against the cavity surface of the mold, it is possible to more reliably prevent the occurrence of sink marks and warpage in the obtained molded product, and stable injection molding of the molded product can be performed. The shape accuracy of the product can be improved. Furthermore, since the volume flow rate V ₁ of the pressurized fluid introduced into the hollow portion and the volume flow rate V ₂ of the pressurized fluid discharged out of the system are controlled, the pressurized fluid introduced into the thermoplastic resin in the cavity is controlled. The degree of freedom of control of the pressure change profile is increased, so that a more stable molded product can be injection molded, and the shape accuracy of the molded product can be further improved.

In this way, by controlling the pressure of the pressurized fluid in the hollow portion, it is possible to reliably prevent sink marks and warpage in the molded product, but when the pressure of the pressurized fluid in the hollow portion is too low In this case, sink marks are likely to occur in the thick part of the molded product, and warping is likely to occur when the pressure of the pressurized fluid is too high. Therefore, the optimum pressure of the pressurized fluid may be appropriately determined according to the shape of the molded product and the material used by performing various tests. Further, the values of the volume flow rate V ₁ and the volume flow rate V ₂ for obtaining the desired pressure P ₀ of the optimum pressurized fluid may be appropriately determined according to various tests and the shape of the molded product and the material used. . It should be noted that an abnormality has occurred when the pressure measurement result of the pressurized fluid in the hollow portion changes or changes despite the fact that there is no change in the values of the volume flow rates V ₁ and V ₂ .

  The second embodiment is a modification of the first embodiment. FIG. 4 shows a conceptual diagram of the mold assembly of the second embodiment including the pressurized fluid introducing device. In the mold assembly according to the second embodiment, the cavity includes a main cavity portion 15A into which the molten thermoplastic resin is injected, and a discarded cavity portion 15B (overflow cavity portion 15B) communicating with the main cavity portion 15A. . Then, the pressurized fluid in the hollow portion 17 is discharged out of the system through the discarding cavity portion 15B and the second proportional flow rate control valve 52. The tip of the pressurized fluid discharge nozzle 42 is disposed so as to be disposed in the discarded cavity portion 15B. That is, when in the forward position, the tip of the pressurized fluid discharge nozzle 42 is positioned in the discard cavity 15B. When in the retracted position, the tip of the pressurized fluid discharge nozzle 42 is located in the same plane as the cavity surface of the mold (specifically, the second mold section 12).

  In the injection molding method in Example 2, in the same process as [Step-100] in Example 1, molten thermoplastic resin is injected into the main cavity portion 15A, and [Step-110] in Example 1 is injected. In the same process, a pressurized fluid is introduced into the molten thermoplastic resin 16 in the cavity, and the hollow portion 17 is formed inside the molten thermoplastic resin 16. The molten thermoplastic resin 16 extends to the discarded cavity portion 15B, and the hollow portion 17 also extends to the portion of the molten thermoplastic resin 16 in the discarded cavity portion 15B (see FIG. 5A). Thereafter, in the same step as [Step-120] in Example 1, a discharge hole communicating with the hollow portion 17 is formed in the molten thermoplastic resin 16. Specifically, the pressurized fluid discharge nozzle 42 is positioned at the forward movement position (see FIG. 5B). As a result, a discharge hole communicating with the hollow portion 17 can be formed in the molten thermoplastic resin 16. Thereafter, by performing the same steps as [Step-120] to [Step-140] of Example 1, a molded article having the hollow portion 17 can be obtained.

  Alternatively, as shown in FIG. 5C, in the same step as [Step-110] in Example 1, a pressurized fluid is introduced into the molten thermoplastic resin 16 in the cavity, and the molten thermoplastic resin 16 is hollow. Although the portion 17 is formed, the volume of the molten thermoplastic resin injected into the cavity may be adjusted so that the molten thermoplastic resin 16 is discarded and extends partway through the cavity portion 15B. In this case, when the hollow portion is formed in the molten thermoplastic resin 16 in the discarded cavity portion 15B, a part of the molten thermoplastic resin 16 is blown away by the pressurized fluid, and a discharge hole is formed in the molten thermoplastic resin 16. . The pressurized fluid discharge nozzle 42 may be left in the retracted position.

  Except for the above points, the configuration and structure of the mold assembly of the second embodiment can be the same as the configuration and structure of the mold assembly described in the first embodiment, and the mold assembly of the second embodiment. Since the injection molding method using a three-dimensional object can be the same as the injection molding method using the mold assembly of Example 1, detailed description thereof is omitted.

The third embodiment is a modification of the first or second embodiment. A conceptual diagram of the mold assembly of Example 3 including the pressurized fluid introducing device is shown in FIG. In the third embodiment, the pressurized fluid buffer storage device 34 (specifically, the pressurized fluid flow path portion 62 located between the first proportional flow rate control valve 51 and the pressurized fluid introducing means 41 includes A kind of monitoring coil in which a buffer tank and piping are wound in a coil shape) is arranged. Usually, the volume of the hollow portion 17 is not as large as the left. Therefore, in some cases, it may be difficult to control the volume flow rates V ₁ and V ₂ based on the small volume of the hollow portion 17. By providing the pressurized fluid buffer storage device 34, the volume flow rates V ₁ and V ₂ can be controlled based on a large volume such as the sum of the volume of the hollow portion 17 and the volume of the pressurized fluid buffer storage device 34. The controllability of the volume flow rates V ₁ and V ₂ can be improved.

In the example shown in FIG. 6, the first proportional flow rate control valve 51, the pressurized fluid buffer storage device 34, and the pressurized fluid introduction means 41 are arranged in this order in the pressurized fluid flow path portion 61. FIG. 7 shows a conceptual diagram of a modified example of the mold assembly including the pressurized fluid introduction device of Example 3, and a pressurized fluid flow path portion 61 in which a first proportional flow rate control valve 51 is disposed, In parallel, a third proportional flow rate control valve (first diaphragm regulator) 53 and a pressurized fluid buffer storage device 34 are disposed between the pressurized fluid supply device 30 and the pressurized fluid introduction means 41. Alternatively, the pressurized fluid channel 64 may be provided. Based on the pressure measurement result of the pressure measuring means 54, the operation of the electropneumatic regulator 55 is controlled, and the electropneumatic regulator 55 also drives the third proportional flow rate control valve (third diaphragm regulator) 53, so that the first A proportional flow control valve (first diaphragm regulator) 51 and a third proportional flow control valve (third diaphragm regulator) 53 add pressure supplied from the pressurized fluid supply device 30 to the pressurized fluid introducing means 41. The volume flow rate V _{1 of the} pressurized fluid is controlled. Incidentally, a hollow portion is formed based on the control of the first proportional flow control valve 51 from time t ₀ to time t ₁ shown in FIG. 3, and the third proportional flow rate from time t ₁ to time t ₄ . it may control the volume flow through the control valve 53 or alternatively, at time t ₀ ~ time t _4, the control of the volume flow by a first proportional flow control valve 51 and the third proportional flow control valve 53 You may go.

  Except for the above points, the configuration and structure of the mold assembly of the third embodiment can be the same as the configuration and structure of the mold assembly described in the first and second embodiments. Since the injection molding method using the mold assembly can be the same as the injection molding method using the mold assembly of Examples 1 to 2, detailed description thereof is omitted.

  The fourth embodiment is a modification of the first to third embodiments. As shown in FIG. 8, a conceptual diagram of the mold assembly of the fourth embodiment including the pressurized fluid introducing device is the first proportional flow rate control valve 51, the pressurized fluid introducing means 41, and the fourth embodiment. Is connected to a pressurized fluid path portion 63 for discharging the pressurized fluid in the hollow portion out of the system, and a second proportional flow rate control is connected to the pressurized fluid path portion 63. A valve 52 is provided.

In the fourth embodiment, the second proportional flow control valve 52 is kept closed in [Step-120] of the first embodiment. Then, in a step similar to [Step-130] of Example 1 (see time t ₃ ~ time t ₄ when shown in FIG. 3), a predetermined pressure P _0, and, for example, changing the volume flow V ₂ Thus, the volume flow rate V ₁ is changed. As a result, since the flow of the pressurized fluid is generated in the hollow portion 17, the thermoplastic resin in the cavity can be cooled and solidified in a shorter time. The discharge hole communicating with the hollow portion 17 is not formed in the molded product.

  Except for the above points, the configuration and structure of the mold assembly of the fourth embodiment can be the same as the configuration and structure of the mold assembly described in the first to third embodiments. Since the injection molding method using the mold assembly can be the same as the injection molding method using the mold assembly of the first to third embodiments, detailed description thereof is omitted.

  In Example 5, a pressurized fluid supply device will be described. As shown in a conceptual diagram (schematic diagram) in FIG. 9, the pressurized fluid supply device 30 includes a pressurized fluid source 31 (consisting of a PSA type nitrogen gas generator) that generates a pressurized fluid, and a pressurized fluid source 31. The oil separator 32 having a well-known configuration and structure for removing oil in the pressurized fluid from the oil separator 32 and a strainer 33 for further removing oil in the pressurized fluid from the oil separator 32 are provided. The strainer 33 has a double tube structure of an inner cylinder 73 and an outer cylinder 71, and the inside of the outer cylinder 71 has a spiral shape with respect to the pressurized fluid introduced into the outer cylinder 71 from one end of the outer cylinder 71. A plurality of blades 72 are provided for generating a flow. The inner cylinder 73 is filled with a first oil removal layer 74 made of felt, a second oil removal layer 76 made of felt, and a space between the first oil removal layer 74 and the second oil removal layer 76. The activated carbon layer 75 is provided. The pressurized fluid introduced into the outer cylinder 71 from one end of the outer cylinder 71 passes through the inside of the outer cylinder 71 while turning, and is introduced into the inner cylinder 73. The first oil removal layer 74, activated carbon It passes through the layer 75 and the second oil removal layer 76, is discharged from the inner cylinder 73, and is sent to the first proportional flow control valve 51. The activated carbon constituting the felt and the activated carbon layer is made of a known material. The pressurized fluid supply device 30 described above can be applied to the mold assembly described in the first to fourth embodiments.

  As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to these Examples. Structures and configurations of mold assemblies and molds, pressurized fluid introduction devices, pressurized fluid supply devices, etc. described in the examples, thermoplastic resins used in the examples, injection molding conditions, cooling / solidification conditions, The shape of the molded product, the dimensions of the cavity, and the like are examples, and can be changed as appropriate. In the embodiment, the structure of the mold assembly is a single molded product, but it is also possible to have a large number of molded products.

DESCRIPTION OF SYMBOLS 10 ... Mold assembly, 11 ... 1st mold part (fixed mold part), 12 ... 2nd mold part (movable mold part), 13 ... Molten resin injection | pouring Part, 13A ... resin flow path, 14 ... cavity, 15A ... main cavity part, 15B ... discarded cavity part, 16 ... molten thermoplastic resin, 17 ... hollow part, 20 · .... Pressurized fluid introduction device, 30 ... Pressurized fluid supply device, 31 ... Pressurized fluid source, 32 ... Oil separator, 33 ... Strainer, 41 ... Pressurized fluid introduction means ( Pressurized fluid injection nozzle), 42... Pressurized fluid discharge nozzle, 51... First proportional flow control valve (first diaphragm regulator), 52. 2 diaphragm type regulator), 53... Third proportional flow control valve (third diaphragm) Regulator), 54 ... pressure measuring means, 55 ... electro-pneumatic regulator, 61, 62, 63, 64, ... pressurized fluid flow path (part), 71 ... outer cylinder, 72 ... Blade, 73 ... inner cylinder, 74 ... first oil removal layer, 75 ... activated carbon layer, 76 ... second oil removal layer

Claims (20)

A pressurized fluid introduction device for injecting a molten thermoplastic resin into a cavity provided in a mold and introducing a pressurized fluid into the molten thermoplastic resin in the cavity to form a molded product having a hollow portion. There,
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. to control the volume flow,
In parallel with the portion of the pressurized fluid flow path in which the first proportional flow control valve is disposed, the third proportional flow control valve and the pressurization are provided between the pressurized fluid supply device and the pressurized fluid introducing means. A pressurized fluid introduction device characterized in that a pressurized fluid flow path in which a fluid buffer storage device is disposed is provided . A pressurized fluid introduction device for injecting a molten thermoplastic resin into a cavity provided in a mold and introducing a pressurized fluid into the molten thermoplastic resin in the cavity to form a molded product having a hollow portion. There,
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
The pressurized fluid consists of nitrogen gas,
The pressurized fluid supply device further includes: a pressurized fluid source that generates a pressurized fluid; an oil separator that removes oil in the pressurized fluid from the pressurized fluid source; and an oil in the pressurized fluid from the oil separator. A strainer to remove,
The strainer has a double pipe structure of an inner cylinder and an outer cylinder,
Inside the outer cylinder, there are provided a plurality of blades for generating a spiral flow in the pressurized fluid introduced into the outer cylinder from one end of the outer cylinder,
The inner cylinder includes a first oil removing layer made of felt, a second oil removing layer made of felt, and an activated carbon layer filled between the first oil removing layer and the second oil removing layer. A pressurized fluid introduction device characterized by comprising: The pressurized fluid introduced into the outer cylinder from one end of the outer cylinder passes through the outer cylinder, is introduced into the inner cylinder, passes through the first oil removal layer, the activated carbon layer, and the second oil removal layer. The pressurized fluid introduction device according to claim 2 , wherein the pressurized fluid introduction device is discharged from the inner cylinder. Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means is controlled by the << first proportional flow control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
The pressurized fluid introduction device according to any one of claims 1 to 3, wherein the first proportional flow control valve is driven by the electropneumatic regulator. Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means is controlled by the << second proportional flow rate control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
The pressurized fluid introduction device according to any one of claims 1 to 4, wherein the second proportional flow control valve is driven by the electropneumatic regulator. A pressurized fluid introduction device for injecting a molten thermoplastic resin into a cavity provided in a mold and introducing a pressurized fluid into the molten thermoplastic resin in the cavity to form a molded product having a hollow portion. There,
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means is controlled by the << first proportional flow control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
An apparatus for introducing a pressurized fluid, wherein the << first proportional flow control valve >> is driven by an electropneumatic regulator. The pressurized fluid introduction device according to claim 6, wherein the first proportional flow control valve is constituted by a diaphragm regulator. The pressurized fluid introduction device according to claim 6 or 7, wherein the second proportional flow control valve is driven by the electropneumatic regulator. A pressurized fluid introduction device for injecting a molten thermoplastic resin into a cavity provided in a mold and introducing a pressurized fluid into the molten thermoplastic resin in the cavity to form a molded product having a hollow portion. There,
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid discharged out of the system is controlled by the << second proportional flow control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
An apparatus for introducing a pressurized fluid, wherein the << second proportional flow rate control valve >> is driven by an electropneumatic regulator. The pressurized fluid introduction device according to claim 9, wherein the second proportional flow control valve is constituted by a diaphragm regulator. A pressure fluid discharge nozzle having a tip opened in the cavity;
Pressurized fluid in the hollow portion through the pressurized fluid discharge nozzle and a second proportional flow control valve, according to any one of claims 1 to 10, characterized in that it is discharged out of the system Pressurized fluid introduction device. The cavity is composed of a main cavity portion into which the molten thermoplastic resin is injected, and a discarded cavity portion communicating with the main cavity portion.
12. The pressurized fluid according to claim 1 , wherein the pressurized fluid in the hollow portion is discharged out of the system through the discarding cavity portion and the second proportional flow rate control valve. Pressure fluid introduction device. The portion of the pressurized fluid flow path positioned between the first proportional flow control valve and the pressurized fluid introducing means, according to claim 1 or claims, characterized in that pressurized fluid buffer storage device is arranged Item 13. The pressurized fluid introduction device according to any one of items 12 . The pressurized fluid introduction device according to any one of claims 1 to 13 , wherein the pressurized fluid introduction means includes a pressurized fluid injection nozzle having a tip opened in a cavity. (A) a first mold part;
(B) a second mold part,
(C) a cavity formed by clamping the first mold part and the second mold part,
(D) a molten resin injection part opened in the cavity, and
(E) a pressurized fluid introduction device for introducing a pressurized fluid into the molten thermoplastic resin injected into the cavity to form a molded article having a hollow portion;
With
Pressurized fluid introduction device
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. to control the volume flow,
In parallel with the portion of the pressurized fluid flow path in which the first proportional flow control valve is disposed, the third proportional flow control valve and the pressurization are provided between the pressurized fluid supply device and the pressurized fluid introducing means. A mold assembly comprising a pressurized fluid flow path in which a fluid buffer storage device is disposed . (A) a first mold part;
(B) a second mold part,
(C) a cavity formed by clamping the first mold part and the second mold part,
(D) a molten resin injection part opened in the cavity, and
(E) a pressurized fluid introduction device for introducing a pressurized fluid into the molten thermoplastic resin injected into the cavity to form a molded article having a hollow portion;
With
Pressurized fluid introduction device
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
The pressurized fluid consists of nitrogen gas,
The pressurized fluid supply device further includes: a pressurized fluid source that generates a pressurized fluid; an oil separator that removes oil in the pressurized fluid from the pressurized fluid source; and an oil in the pressurized fluid from the oil separator. A strainer to remove,
The strainer has a double pipe structure of an inner cylinder and an outer cylinder,
Inside the outer cylinder, there are provided a plurality of blades for generating a spiral flow in the pressurized fluid introduced into the outer cylinder from one end of the outer cylinder,
The inner cylinder is provided with a first oil removal layer made of felt, a second oil removal layer made of felt, and an activated carbon layer filled between the first oil removal layer and the second oil removal layer. A mold assembly characterized by that. (A) a first mold part;
(B) a second mold part,
(C) a cavity formed by clamping the first mold part and the second mold part,
(D) a molten resin injection part opened in the cavity, and
(E) a pressurized fluid introduction device for introducing a pressurized fluid into the molten thermoplastic resin injected into the cavity to form a molded article having a hollow portion;
With
Pressurized fluid introduction device
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means is controlled by the << first proportional flow control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
A mold assembly, wherein the first proportional flow control valve is driven by an electropneumatic regulator. (A) a first mold part;
(B) a second mold part,
(C) a cavity formed by clamping the first mold part and the second mold part,
(D) a molten resin injection part opened in the cavity, and
(E) a pressurized fluid introduction device for introducing a pressurized fluid into the molten thermoplastic resin injected into the cavity to form a molded article having a hollow portion;
With
Pressurized fluid introduction device
(A) Pressurized fluid supply device,
(B) a pressurized fluid introducing means for introducing a pressurized fluid into the molten thermoplastic resin in the cavity;
(C) a first proportional flow rate control valve disposed in a portion of the pressurized fluid flow channel located between the pressurized fluid supply device and the pressurized fluid introducing means,
(D) a second proportional flow rate control valve disposed in a portion of the pressurized fluid flow path for discharging the pressurized fluid in the hollow portion out of the system, and
(E) Pressure measuring means disposed in a portion of the pressurized fluid flow path located between the first proportional flow control valve and the second proportional flow control valve;
Consists of
The pressure measurement means measures the pressure of the pressurized fluid in the hollow part,
The first proportional flow rate control valve controls the volume flow rate of the pressurized fluid flowing into the hollow portion so that the desired pressure is obtained, and the second proportional flow rate control valve is the pressurized fluid discharged outside the system. Control the volume flow rate of
Based on the pressure measurement result of the pressure measuring means, the volume flow rate of the pressurized fluid supplied from the pressurized fluid supply device to the pressurized fluid introducing means is controlled by the << second proportional flow rate control valve >>
An electropneumatic regulator,
Based on the pressure measurement result of the pressure measuring means, the operation of the electropneumatic regulator is controlled,
A mold assembly, wherein the << second proportional flow control valve >> is driven by an electropneumatic regulator. An injection molding method in which a molten thermoplastic resin is injected into a cavity provided in a mold, a pressurized fluid is introduced into the molten thermoplastic resin in the cavity, and a molded product having a hollow portion is formed,
Started injection of molten thermoplastic resin into the cavity,
During injection of the molten thermoplastic resin into the cavity, a pressurized fluid is introduced into the molten thermoplastic resin in the cavity simultaneously with or after the injection is completed, and a hollow portion is formed inside the molten thermoplastic resin. Forming, then
After cooling and solidifying the thermoplastic resin in the cavity with pressurized fluid,
Open the mold and take out the molded product.
It has each process,
In the process of cooling and solidifying the thermoplastic resin in the cavity, the pressure of the pressurized fluid in the hollow portion is measured, and the volumetric flow rate of the pressurized fluid introduced into the hollow portion and the outside of the system so that the desired pressure is obtained. By controlling the volume flow rate of the pressurized fluid discharged into the chamber and controlling the difference between the volume flow rate of the pressurized fluid introduced into the hollow portion and the volume flow rate of the pressurized fluid discharged out of the system. An injection molding method characterized by setting a constant pressure . A discharge hole communicating with the hollow part is formed in the molten thermoplastic resin,
20. The injection molding method according to claim 19, wherein the pressurized fluid is discharged out of the system from the hollow portion through the discharge hole.

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