WO2012173224A1 - 射出成形方法 - Google Patents

射出成形方法 Download PDF

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Publication number
WO2012173224A1
WO2012173224A1 PCT/JP2012/065334 JP2012065334W WO2012173224A1 WO 2012173224 A1 WO2012173224 A1 WO 2012173224A1 JP 2012065334 W JP2012065334 W JP 2012065334W WO 2012173224 A1 WO2012173224 A1 WO 2012173224A1
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WO
WIPO (PCT)
Prior art keywords
screw
molding material
molding
injection molding
cylinder
Prior art date
Application number
PCT/JP2012/065334
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
小倉　徹
河崎　英敏
盛男 藤原
Original Assignee
富士フイルム株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 富士フイルム株式会社 filed Critical 富士フイルム株式会社
Priority to CN201280026712.XA priority Critical patent/CN103561933A/zh
Priority to KR1020137029675A priority patent/KR20140027244A/ko
Publication of WO2012173224A1 publication Critical patent/WO2012173224A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/47—Means for plasticising or homogenising the moulding material or forcing it into the mould using screws
    • B29C45/50—Axially movable screw
    • B29C45/5008—Drive means therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B29C45/77—Measuring, controlling or regulating of velocity or pressure of moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76003—Measured parameter
    • B29C2945/76006—Pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76177—Location of measurement
    • B29C2945/7618—Injection unit
    • B29C2945/7621—Injection unit nozzle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76344—Phase or stage of measurement
    • B29C2945/76367—Metering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76451—Measurement means
    • B29C2945/76481—Strain gauges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76494—Controlled parameter
    • B29C2945/76498—Pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76494—Controlled parameter
    • B29C2945/76518—Energy, power
    • B29C2945/76521—Energy, power power
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76655—Location of control
    • B29C2945/76658—Injection unit
    • B29C2945/76692—Injection unit drive means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
    • B29C2945/76—Measuring, controlling or regulating
    • B29C2945/76929—Controlling method
    • B29C2945/76933—The operating conditions are corrected immediately, during the same phase or cycle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0012—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular thermal properties
    • B29K2995/0016—Non-flammable or resistant to heat

Definitions

  • the present invention relates to an injection molding method in which a melt molding material is injected into a mold using a screw having a metering function.
  • An injection molding method is widely known as a representative plastic molding.
  • an injection molding machine in which a screw is disposed in a heating cylinder, and a mold composed of a male mold and a female mold are used.
  • a metering step also referred to as a plasticizing metering step
  • a mold clamping step an injection filling step, a pressure holding and cooling step, and a mold release step are sequentially executed.
  • a molding material mainly composed of plastic is supplied into the heating cylinder.
  • the molding material is fed toward the cylinder tip while being melted by the heat from the heating cylinder and the frictional heat generated by the screw rotation.
  • This melt molding material is stored at the tip of the cylinder without flowing out of the nozzle.
  • the rotating screw is pressed backward and moved backward in the direction opposite to the nozzle. From the retreated position of the screw, the storage amount of the melt molding material is measured.
  • the screw returns to the predetermined retracted position, the rotation of the screw is stopped and the metering process ends.
  • the nozzle at the tip of the heating cylinder is connected to the mold gate.
  • the molten molding material is injected and filled into the cavity in the mold with a high pressure by moving toward the tip of the cylinder while the rotation of the screw is stopped.
  • the nozzle is kept pressed against the gate of the mold so that the melt molding material in the mold is maintained at a predetermined pressure.
  • the mold is cooled to solidify the molded product.
  • the mold is separated into a male mold and a female mold, and the molded product is taken out.
  • the molding material in the hopper is supplied to the heating cylinder.
  • a sufficient amount of molding material exceeding the molding material required for one injection molding is stored in the hopper, and the molding material is sequentially supplied into the heating cylinder by its own weight.
  • a supply method (referred to as a normal supply method) in which the molding material is supplied from the hopper into the heating cylinder by its own weight in accordance with the screw feed amount, and the heating cylinder is always filled with the molding material is generally used.
  • the molding material supplied into the heating cylinder is melted and stirred, and sent to the liquid reservoir at the tip of the cylinder as a molten molding material.
  • This melt molding material is prevented from leaking from the tip of the nozzle by a shut-off nozzle (nozzle equipped with a needle-like valve) or the like, and therefore accumulates in the liquid reservoir.
  • the screw is retracted under the pressure.
  • melt molding material rotates together with the screw (referred to as “both around”), the melt molding material cannot be conveyed to the liquid reservoir.
  • melt molding material rotates slower than the rotation of the screw or does not rotate due to friction between the melt molding material and the cylinder inner wall (both the positional relationship with the screw changes). is required.
  • melt molding material has a high density or has a large friction
  • the melt molding material when the melt molding material is pressed against the inner wall of the cylinder, it sticks to the inner wall of the cylinder and is difficult to move.
  • screw when the screw tries to push the melt molding material, the screw itself may be retracted against the resistance of the melt molding material adhered to the inner wall of the cylinder (this is referred to as “screwing phenomenon”). This acts so that the melt molding material adhered to the inner wall of the cylinder functions as a nut and the screw functions as a bolt, and only the screw moves backward.
  • Japanese Patent Application Laid-Open No. 2003-21508 describes an injection molding machine that can manufacture a high-quality molded product that does not cause internal distortion or the like by controlling the retreating force and the advancing force of a screw.
  • the molding material in the metering process, the molding material is supplied to the heating cylinder at a constant rate, and the screw rotates at a constant speed in the heating cylinder, and the molten molding material is stored in the liquid reservoir at the tip of the heating cylinder.
  • a pressure sensor that measures the molten resin pressure is disposed in the liquid reservoir. While monitoring the resin pressure with the pressure sensor, the axial position of the screw is adjusted so that the resin pressure is maintained at a predetermined value, thereby adjusting the volume of the liquid reservoir.
  • the resin pressure is sent to the calculation unit, and the backward force acting on the tip of the screw is calculated using the cross-sectional area of the screw.
  • the servo motor generates a forward force having the same magnitude as the backward force and presses the rear end of the screw. This balances the retreating force and the advancing force of the screw in a weighing process or the like.
  • Japanese Patent Application Laid-Open No. 2006-272867 describes an injection molding machine that prevents a mold and a screw from being damaged due to abnormal resin pressure during an injection / holding process.
  • a resin pressure sensor is disposed in the liquid reservoir.
  • a back pressure sensor acting on the rear end of the screw is provided.
  • the controller compares the resin pressure measured by the resin pressure sensor with the back pressure value measured by the back pressure sensor during the injection / holding process, and if the difference between the two measured values is within the allowable range.
  • the injection / holding process is continued, and when it is outside the allowable range, the injection / holding process is forcibly terminated to prevent damage to the mold or the like.
  • a resin material derived from a living organism such as a plant instead of a petroleum resin material.
  • a resin material is also referred to as a biomass resin (bioplastic).
  • a polylactic acid resin (PLA) or a cellulose resin is carbon neutral, and its practical application has been studied.
  • PLA polylactic acid resin
  • a cellulose resin is carbon neutral, and its practical application has been studied.
  • many of the molded products made of biomass resin have poor heat resistance compared to molded products of general resins, and have a drawback that the molded products are easily burnt.
  • the heat resistance and flame retardancy of biomass resin can be improved by mixing additives.
  • various additives according to the purpose are mixed into the base resin as the main component, these materials are put all at once into a kneader and mixed and dispersed thoroughly. Body pellet material. Then, the pellet material thus obtained may be put into an injection molding machine and molded.
  • powdery additives are indispensable to improve the flame retardancy of molded products, and many of these additives are added to the kneader together with the biomass resin.
  • a powdery additive for enhancing heat resistance As described above, for example, in order to obtain a high-quality molded product with a biomass resin having improved heat resistance, in addition to a granular base resin as a main component, a powdery additive for enhancing heat resistance A DM molding method in which is directly put into an injection molding machine is advantageous. However, additives for increasing the heat resistance generally lower the mechanical strength. Therefore, additives such as powder additives and compatibilizers are also used in combination.
  • the molding material is sufficiently mixed in a cylinder and stable weighing is performed.
  • a molding material made of a plurality of materials including a granular material as a base resin and a powdery additive is supplied into a heating cylinder from an inlet, and a screw is provided inside the heating cylinder.
  • the molding material is sent to the tip of the cylinder and stored while being kneaded and dispersed in the cylinder.
  • the screw is retracted by the pressing force from the stored molding material, and the metering is completed when the screw is retracted to the weighing setting position.Then, the screw is advanced and the material is pushed into the mold at a high pressure to perform injection molding. Is called.
  • the pressure from the molding material stored in the cylinder tip is detected.
  • the molding material is supplied by a limited supply that is sparsely charged from the inlet, and the molding material is supplied directly below the inlet while leaving a gap in the molding material transfer space formed between the inner wall of the heating cylinder and the screw. Is done. With this limited supply, the time required for metering is the standard when filling and supplying granular material while filling the molding material transfer space formed between the inner wall of the heating cylinder and the screw directly under the inlet. Make it longer than the weighing time.
  • the weighing time of the present invention is preferably 1.5 to 3 times the above-mentioned standard weighing time. If the metering time is shorter than the lower limit of this range, kneading between the granular base resin and the powdered additive tends to be insufficient, and if the metering time is longer than the upper limit, the molding material, especially powdery additive There is concern about thermal degradation of Such conditions are particularly suitable when the ratio of the powdery additive is 30% by weight or more of the granular material.
  • a polylactic acid resin or a cellulose resin can be used as a base resin, and a flame retardant or a compatibilizing agent can be used as an additive.
  • a method of continuously supplying the granular base resin and the powdered additive in small amounts into the heating cylinder Further, there are a method of intermittently supplying these materials to the cylinder, a method of alternately supplying a granular base resin and a powdery additive.
  • the molding cycle includes a weighing process, a mold clamping process, an injection filling process, a pressure holding cooling process, and a mold release process, and the molding material is measured between the start of the pressure holding cooling process and the end of the mold release process. Is done.
  • the present invention there is no great variation in weight even when different materials such as granular and powder are not kneaded sufficiently and are directly fed to the cylinder of the injection molding machine and molded. A molded product with stable quality can be obtained.
  • the method of the present invention is also effective for a pellet material such as an elastomer whose resin resistance on the inner wall of the cylinder varies greatly depending on the shape and supply state of the pellet.
  • Schematic configuration diagram of an injection molding apparatus for carrying out the injection molding method of the present invention Diagram explaining the zone configuration of the screw Diagram explaining injection molding cycle The figure explaining the position of the screw in the middle of the measurement process The figure explaining the position of the screw at the end of the weighing process The figure explaining the position of the screw in the injection and filling process The figure explaining the position of the screw in a mold opening and a measurement process.
  • an in-line screw type injection molding apparatus 10 suitably used in the method of the present invention includes a heating cylinder 13 having a nozzle 12 at its tip, and a screw 14 is rotatably disposed therein.
  • a drive device 18 is provided that includes a motor 16 that rotates the screw 14 and a piston 17 that moves the screw 14 in the axial direction (left and right direction in FIG. 1).
  • the piston 17 is provided with a back pressure sensor 21 and a position sensor 22.
  • the back pressure sensor 21 detects a back pressure that generates a resistance force when the screw 14 moves backward in the measuring process.
  • the position sensor 22 detects the retracted position of the screw 14, that is, the measurement completion position.
  • the driving device 18 has a function of controlling the back pressure of the piston 17 in cooperation with the controller 25.
  • the drive device 18 is provided with a pump 19a, a pressure adjusting device 20, and a servo valve 20a that are on / off controlled in response to a command from the controller 25.
  • the pump 19a supplies air from the tank 19 to the piston 17 according to the back pressure.
  • the pressure adjusting device 20 sets the back pressure of the piston 17 in accordance with a setting instruction from the controller 25.
  • the servo valve 20a is feedback-controlled based on a control signal sent from the controller 25 according to the back pressure value detected by the back pressure sensor 21 so that the back pressure set by the pressure regulator 20 is maintained.
  • a heater 26 is wound around the outer periphery of the heating cylinder 13 to heat the molding material supplied to the inside of the heating cylinder 13 at a predetermined temperature necessary for plasticization.
  • the molding die 30 includes a fixed mold 32 having a cavity 31 formed therein and a movable mold 33, and the tip of the nozzle 12 is connected to a sprue 34 of the fixed mold 32. Further, the piston 17 presses and moves the screw 14 in the left direction (forward direction) in FIG. 1 to perform an injection operation, and the molten resin is injected into the molding die 30 through the nozzle 12 with a predetermined pressure. .
  • a charging port 28 is formed on the rear end side in the length direction of the heating cylinder 13, and a hopper 40 is attached above the charging port 28.
  • a material supply device 50 is provided above the hopper 40, and the molding material supplied from the material supply device 50 is supplied into the heating cylinder 13 through the hopper 40 and the inlet 28.
  • the material supply device 50 includes drums 51 and 53.
  • the drum 51 is charged with a biomass resin 45, which is a granular material, as a base resin that is a main component of the molding material, and the drum 53 is added with a powdery material.
  • the object 46 is thrown in.
  • Measured feeders 52 and 54 are provided at the outlets of the drums 51 and 53, and the biomass resin 45 and the additive 46 that have been measured are supplied to the hopper 40 from the respective measured feeders 52 and 54.
  • a general molding material in the form of granules called pellets it is standard that the molding material is supplied to the hopper 40 without interruption due to its own weight. For this reason, immediately below the inlet 28, the molding material is densely filled so that there is almost no gap in the space formed between the inner wall of the heating cylinder 13 and the screw 14.
  • each of the biomass resin 45 and the additive 46 is weighed by the weighing feeders 52 and 54, and then is supplied to the hopper 40 little by little over time. Specifically, a certain amount of the biomass resin 45 and the additive 46 are temporally from the time when the screw 14 is rotated and the measuring process is started until the screw 14 is stopped and the measuring process is completed. Dispersed and supplied to the hopper 40. For this reason, the biomass resin 45 and the additive 46 are supplied immediately below the charging port 28 while creating a gap in the molding material transfer space formed between the inner wall of the heating cylinder 13 and the screw 14.
  • each of them when supplying the biomass resin 45 and the additive 46 from the weighing feeders 52 and 54 to the hopper 40, each of them is continuously supplied in small quantities during the weighing process period, or each of them is fed during the weighing process period. At the same time, it may be intermittently supplied in small increments, or may be alternately supplied in small amounts.
  • the measuring feeder is not particularly limited as long as it does not interfere with the supply of the molding material, and a screw feeder, a vibratory feeder, a pocket-type constant-capacity feeder, a table feeder, a circle feeder, or the like can be used.
  • the controller 25 includes a type of molding material (type of resin, type of additive, etc.), shape of the material (powder, granule, liquid, pellet), mixing ratio (ratio of base resin and additive), injection Depending on various factors such as molding conditions (injection amount per shot, cylinder heating temperature, screw rotation speed, back pressure setting value, etc.), the necessary kneading time data required for uniform and sufficient mixing of the molding material Have been entered.
  • the necessary kneading time data obtained in advance by a preliminary test or the like is used.
  • the supply amount of the molding material per unit time in the weighing feeders 52 and 54 with respect to the weighing time is input so that the weighing time becomes equal to or longer than the necessary kneading time.
  • the controller 25 confirms that at the start of the first molding and that the previous molding has entered the holding pressure cooling process based on information from the pressure sensor 27, the back pressure sensor 21 and the position sensor 22 at the tip of the cylinder.
  • Each of the molding materials is started to be supplied from the feeders 52 and 54 to the hopper 40 according to the selected supply program.
  • the screw 14 in the heating cylinder 13 is divided into three zones, a supply zone 41, a compression zone 42, and a metering zone 43 in order from the inlet 28 side.
  • the weighing zone 43 is located immediately below the inlet 28.
  • the molding material charged into the hopper 40 is supplied from the charging port 28 to the supply zone 41, and is conveyed through the heating cylinder 13 to the screw tip side by the rotation of the screw 14.
  • the molding material conveyed in the heating cylinder 13 is gradually caused by shearing heat generated between the surface of the rotating screw 14 and the inner wall of the heating cylinder 13 and heat from the heater 26 provided on the outer periphery of the heating cylinder 13. To be melted.
  • melt-kneading of the molding material is started, and the melt-kneaded molding resin is further conveyed to the tip side and reaches the measuring zone 43.
  • a pressure sensor 27 is provided on the inner wall at the tip of the heating cylinder 13 to detect the pressure of the accumulated molten resin. The detected pressure value is transmitted to the controller 25.
  • the screw 14 receives the pressure and moves backward, and when it reaches the measurement setting position (see FIG. 5), the rotation of the motor 16 is stopped and the backward movement is also stopped. To do.
  • the injection molding cycle is a repetition of a metering process, a mold clamping process, an injection filling process, a pressure keeping cooling process, and a mold release process.
  • the screw 14 is rotated in the heating cylinder 13 by driving the motor 16. Since the molding material is supplied to the heating cylinder 13 through the hopper 40 at the start of the metering process, the molding material is fed to the cylinder tip side while being kneaded and melted (plasticized) by the rotation of the screw 14, and gradually the cylinder tip portion. 15 (see FIG. 4).
  • the mold clamping process is a process of closing the movable mold 33 and the fixed mold 32 in the mold open state to form a molding space in the molding die 30, and the movable mold 33 is moved by a mold clamping cylinder (not shown). It moves in the direction of the fixed mold 32 and makes contact. Thereafter, the nozzle touch for joining the sprue 34 of the fixed mold 32 to the nozzle 12 is performed, but the molding may be repeated in the joined state.
  • the molding material melted in the heating cylinder 13 and in a fluid state and stored in the cylinder tip 15 is transferred from the nozzle 12 to the molding metal by the advance of the screw 14. Injection into the mold 30. Thereby, the molten molding material is filled in the cavity 31 of the molding die 30.
  • the holding pressure cooling step performs holding pressure in which pressure is applied to the cavity 31 by the screw 14 even after being injected and filled, and cooling for solidifying the filled resin in that state. Holding pressure continues to apply pressure to the molding material filled in the cavity 31 of the molding die 30 so that small bubbles are removed and the detailed shape formed in the cavity 31 is transferred to the molded product.
  • the holding pressure is completed substantially in the first half of the holding pressure cooling step, but the cooling is continued after that until the molded product is sufficiently rigid when it is released.
  • the movable mold 33 is moved away from the fixed mold 32 by the mold clamping cylinder to open the molding die 30 (see FIG. 6), and is molded by the protruding pin 35 just before the end of the mold opening operation.
  • the product is released from the movable mold 33.
  • the screw 14 is rotated when the filled resin is solidified to some extent even before the holding pressure is completed, and the next measuring step is started. Moreover, what is necessary is just to complete
  • the metering start time can be shifted later in time, but the molding cycle can be made more efficient by performing the (n + 1) th cycle metering step during the nth cycle holding pressure cooling step as described above. Can do.
  • the controller 25 selects a measurement time required for the molding material from the input necessary kneading time data.
  • the controller 25 starts measuring the biomass resin 45 and the additive 46 for one cycle stored in the measuring feeders 52 and 54 from the measuring feeders 52 and 54 within the measuring time from the start to the end of the measurement.
  • the supply amounts of the biomass resin 45 and the additive 46 per unit time supplied to the hopper 40 are calculated and set in the weighing feeders 52 and 54.
  • both a certain amount of biomass resin 45 and additive 46 weighed by the weighing feeders 52 and 54 are dispersed and supplied to the heating cylinder 13 little by little between the start and end of the weighing process. Will come to be.
  • the metering time in the metering process is determined to be at least 20 seconds.
  • the material for one cycle stored in the measuring feeders 52 and 54 is limitedly supplied to the hopper 40.
  • the supply amount of the material per unit time or the supply speed of the material is supplied from the start of supply. It is preferable to be as uniform as possible until the end. Therefore, a small amount continuous supply method (referred to as flipping) in which the molding material is continuously and gradually dropped from the weighing feeders 52 and 54 to the hopper 40, or an intermittent supply method in which a constant amount is intermittently dropped to the hopper 40 at regular intervals. It is preferable to adopt. In the case of intermittent supply, it may be alternately supplied from the weighing feeders 52 and 54.
  • the controller 25 starts to limit supply of the respective molding materials from the weighing feeders 52 and 54 to the hopper 40 based on the information from the pressure sensor 27, the back pressure sensor 21, and the position sensor 22, and the motor 16 is turned on. Drive to rotate the screw 14.
  • the pressure sensor 27 provided at the cylinder tip 15 detects the resin pressure S (MPa) of the molten molding material, and the back pressure sensor 21 detects the back pressure T that urges the screw 14 forward.
  • the controller 25 calculates a backward force PJ applied to the screw 14 under the resin pressure S, and calculates a forward force PH obtained by multiplying the calculated backward force PJ by a coefficient K. Then, the back pressure T for obtaining the forward force PH is set in the pressure adjusting device 20.
  • the resin resistance at that time becomes a reaction force PT and presses the screw 14 in the backward direction.
  • a reaction force PT due to resin resistance is applied to the screw 14 in the backward direction
  • the forward force PH is reduced by the reaction force PT due to the resin resistance, and the reaction force PT easily fluctuates due to the influence of the rotational speed of the screw 14 and the kneading condition of the molding material.
  • the forward force PH to be added to becomes unstable.
  • the controller 25 keeps the optimum forward force PH so that the forward force PH is not excessive and the fluctuation of the reaction force PT due to the resin resistance can be ignored. To be able to. For this reason, the controller 25 uses the backward force PJ determined corresponding to the resin pressure S detected by the pressure sensor 27 as a reference, and sets a coefficient K set in the range of 1.2 to 2.0 to the backward force PJ. The back pressure T is controlled so that this force “K ⁇ PJ” acts on the screw 14 as the forward force PH.
  • the value of the coefficient K can be prepared in advance according to various factors such as molding materials and molding conditions by conducting preliminary tests and the like in advance. Use it. As a result, even if the reaction force PT due to the resin resistance may fluctuate, the forward force PH is adjusted in a well-balanced manner so as to follow the backward force PJ based on the resin pressure at that time. Therefore, the measurement time (kneading time) does not fluctuate greatly, and a high-quality molded product is obtained while using a molding material composed of a granular base resin and a powdery additive. It becomes possible.
  • the value of the coefficient K is arbitrary as long as it is in the range of “1.2 to 2.0”. Specifically, 1.2, 1.3, 1.5, and 1.8 are prepared and molded. It can be switched as appropriate according to the conditions.
  • the coefficient K is close to 1 or 1, the frictional resistance is almost ignored. For this reason, in reality, the screw 14 is easily retracted due to the frictional resistance of the resin, and the molding material cannot be fed toward the cylinder tip 15, so that the molding material easily rotates together with the screw 14.
  • the coefficient K exceeds “2.0”, the forward force PH with respect to the screw 14 becomes excessive, making it difficult for the screw 14 to move backward, extending the measurement time and causing the thermal deterioration of the molding material.
  • the resin resistance when the screw 14 is rotated increases and is likely to fluctuate. For this reason, it is disadvantageous to keep the rotational speed of the screw 14 constant, but if the molding material supplied to the supply zone 41 is made small by the above-mentioned limited supply, the resin resistance is small and the fluctuation is also suppressed.
  • the reaction force PT can also be reduced.
  • the molding material is dispersed in time and supplied to the heating cylinder 13, it takes time to measure the molding material required for each molded product.
  • the combination of the number of rotations of the screw 14 and the measurement time is as follows in order to ensure that the molding material is in a good state of melting and kneading and does not cause thermal deterioration in the molding material. The combinations shown in [Table 1] are confirmed as appropriate. Since the molding material is only in the form of granules, the coefficient K is set to “2.5”.
  • the measuring time shown in [Table 1] is the standard measuring time at each screw speed
  • the granular material and the powdered material are used by the measuring feeders 52 and 54. Since the feed is distributed in small amounts over time, the metering time at each screw speed should be extended to about 1.5 to 3 times the standard metering time so that the kneading proceeds sufficiently. Is preferred.
  • the upper limit of the measurement time may be preferably less than 3 times in order to avoid staying in the heating cylinder 13 for a long time.
  • the rotational speed of the screw 14 is preferably set to 30 to 300 rpm in consideration of both improvement in kneading performance and deterioration due to shear heat generation, but more preferably in the range of 50 to 200 rpm, which is suitable for each rotational speed. Weighing should be done under weighing time.
  • the rotation speed of the screw 14 is less than 30 rpm, sufficient uniform kneading cannot be performed, and when it exceeds 300 rpm, the molding material may be deteriorated by shearing heat generation.
  • the base resin of the molding material is a biomass resin, the risk of deterioration increases when it exceeds 300 rpm.
  • adding a device for cooling the outside of the heating cylinder of the injection molding machine by means such as air blowing can suppress the temperature rise due to the shear heat generation of the material, and increase the screw rotation speed. Can be set.
  • the injection molding method of the present invention is a standard material supply, that is, a material supply in which granular molding material is poured into the hopper 40 by its own weight, and the space in the measuring zone 41 of the screw 14 is almost densely filled with the molding material.
  • a material supply method is adopted in which the granular material and the powder material are supplied while being limited to small amounts in time so that a gap is generated in the space in the measurement zone 41.
  • the number of rotations of the screw 14 can be appropriately selected from 50 to 200 rpm, for example, but the ratio of the metering time to the standard metering time becomes long.
  • the molding material is not clogged at the outlet of the hopper 40 or inside the heating cylinder 13, the resin resistance when the molding material is transferred forward is kept low, and a uniform kneading action is obtained.
  • a molding test was performed using the injection molding method of the present invention, and samples of Examples 1 to 6 and Comparative Examples 1 to 6 were molded while changing molding conditions. About these samples, the various tests were done on common conditions and the quality was evaluated. Hereinafter, the outline of the molding test and the evaluation result will be described.
  • molding materials The following were used as molding materials. ⁇ Polylactic acid resin (pellet): Nature Works, 4032D 100 parts by weight ⁇ Flame retardant (powder): ADEKA, Adeka Stab FP2200 35 parts by weight ⁇ Compatibilizer (powder): Fushimi Pharmaceutical, Ravitor FP110 20 parts by weight Anti-decomposition agent (powder) ... Mitsubishi Rayon, Metabrene W600A 5 parts by weight, PTFE drip inhibitor (powder) ... Daikin Industries, FA500H 0.5 part by weight, hydrolysis inhibitor (powder) ... Rhein Chemie, Starbuxol 1FL 3 parts by weight, filler (fine powder) ... Nihon Talc Industrial, P3 8 parts by weight ⁇ total> 171.5 parts by weight
  • the polylactic acid resin one previously dried at 80 ° C. for 5 hours in a hot air dryer was used. Moreover, the difficult agent used what was previously dried under reduced pressure for 5 hours at 80 degreeC in the vacuum dryer.
  • the powder ratio of the molding material is 41% by weight.
  • the SG150U-3 manufactured by Sumitomo Heavy Industries, Ltd. was used as the injection molding equipment for the test, and JIS dumbbell test pieces, Charpy test pieces, and UL test pieces (thickness 1.6 mm) were simultaneously injection molded into this injection molding equipment.
  • a mold that can be used was set.
  • the heater temperature of the injection molding apparatus was set to 195 ° C.-195 ° C.-190 ° C.-180 ° C.-30 ° C. from the nozzle side.
  • the injection amount per shot was set to 120 g. In the injection molding, the material was sufficiently purged, and after 50 shots were discarded, 50 shots were molded.
  • test pieces As the mold used for the test molding, those having cavities for molding three types of test pieces used in various tests were used, and three types of test pieces were obtained for each molding process. About the sample for 50 shots, the test piece used for the flame retardance test mentioned later diverted all 50 shots for weight measurement. For the Charpy impact test, break elongation test, and flame retardancy test, 5 pieces obtained every 10 shots out of 50 shots were used as test pieces.
  • the test methods and criteria are as follows.
  • a test piece having a length of 80 mm ⁇ 2 mm, a width of 10 mm ⁇ 0.2 mm, and a thickness of 4 mm ⁇ 0.2 mm was formed according to JISK-7111, and the test piece was notched (notch radius 0). .25 mm ⁇ 0.05 mm and notch width 8.0 mm ⁇ 0.2 mm).
  • the mass of the notched test piece was 4.2 g.
  • the test apparatus used was IMPACTTESTER (analog type) manufactured by TOYOSEIKI. Five specimens sampled every 10 shots were subjected to a Charpy impact test according to JISK-7111, and the case where the minimum value was 5 (KJ / m 2 ) or more was determined to be acceptable.
  • the test piece was molded according to JIS (K-7113, No. 1 type test piece). The test piece was gripped using a Shimadzu autograph (AGS-J type), pulled at a pulling speed (50 mm / min) until it broke, and the elongation at break (breaking elongation) was measured. If the elongation at break of the five test pieces was the lowest and it was 6% or more, it was judged acceptable, and if it was less than 6%, it was judged unacceptable.
  • AGS-J type Shimadzu autograph
  • Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated for each test item, those that passed all of the test items were evaluated as acceptable, and those that failed even at one item were evaluated as failed. . These evaluation results are shown in the following [Table 2] together with the molding conditions and measurement conditions of Examples 1 to 6 and Comparative Examples 1 to 6.
  • “restricted” means a limited supply in which a fixed amount of molding material measured by the measuring feeder is gradually supplied to the hopper during the measuring period. “Filling” means a feeding method in which the molding material is fed to the hopper by its own weight without using a weighing feeder, and the cylinder is filled almost densely.
  • the ratio of the measurement time of each example and comparative example to the standard measurement time for each screw revolution described in [Table 1] is shown. .
  • Comparative Examples 1 and 2 the value of the coefficient K is inappropriate, and the measurement time does not fall within the appropriate range with respect to the screw rotation speed. If the measuring time is short, a plurality of types of molding materials cannot be sufficiently kneaded, and if it is too long, thermal deterioration of the material is inevitable. Even if the coefficient K is in an appropriate range, the measurement time is not in an appropriate range depending on the degree of limited supply, and good evaluation results cannot be obtained (Comparative Examples 3 and 4). Comparative Examples 5 and 6 are material supply by a filling method, and it is understood that there is no practicality when injection molding is performed with a molding material containing 30% by weight or more of a powder material in addition to a granular material.
  • the present invention is not limited to the above-described examples, and various improvements and modifications may be made without departing from the scope of the present invention.
  • the method of the present invention is also effective when injection molding is performed using a pellet material such as an elastomer whose resin resistance (PT) on the cylinder inner wall varies greatly depending on the shape and supply state of the pellet.
  • a pellet material such as an elastomer whose resin resistance (PT) on the cylinder inner wall varies greatly depending on the shape and supply state of the pellet.

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  • Mechanical Engineering (AREA)
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  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
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CN104588656A (zh) * 2014-12-25 2015-05-06 苏州米莫金属科技有限公司 一种温控粉末注射成型装置
JP6552922B2 (ja) * 2015-08-31 2019-07-31 住友重機械工業株式会社 射出成形機
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CN110027170B (zh) * 2019-05-08 2020-11-17 韩山师范学院 一种高分子反应注塑装置
JP7093566B2 (ja) * 2019-10-09 2022-06-30 福井精機工業株式会社 熱可塑性樹脂成形方法および熱可塑性樹脂成形装置
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