Abstract

Provided is an injection molding method that makes it possible to proceed with the opening of a fiber bundle even when the fibers thereof are crushed and said fiber bundle becomes hard and tight. A constricting section 35 is provided to the boundary between a first stage 21 and a second stage 22 of a screw 10. When a mixture of a melted resin M and reinforcing fibers F passes through the constricting section 35, compressive force that is strong compared to upstream from the constricting section 35 is applied to the mixture. A supply section 25 downstream from the constricting section 35 has a shaft diameter D3 that is smaller than the outer diameter D2 of the constricting section 35, thereby causing the vicinity of the supply section 25 to act as a decompression area in which the mixture that has passed through the constricting section 35 expands. As a result, springback occurs in the reinforcing fibers F and the Barus effect occurs in the melted resin M, thereby making it possible to produce a state that is useful for opening a fiber bundle.

IPC Classes  ?

• B29C 45/60 - Screws
• B29C 45/50 - Axially movable screw

Abstract

Provided is a screw that is for use in an injection molding machine and that makes it possible to benefit from the kneading effect of a multi-start screw while minimizing the received friction resistance. The screw for an injection molding machine is provided with a first stage 20 on the upstream side and a second stage 30 on the downstream side. The screw for an injection molding machine is characterized in that: the first stage 20 is provided with a compression section 22 comprising a main scraper 25 and an auxiliary scraper 26 having a smaller outer diameter than the main scraper 25; and the second stage 30 is provided with a multi-start screw section 31, said multi-start screw section being provided on the upstream side and comprising a plurality of scrapers, and a fin kneading section 32 provided downstream from the multi-start screw section.

IPC Classes  ?

• B29C 45/60 - Screws
• B29C 45/50 - Axially movable screw

Abstract

Provided is a temperature control method capable of causing the heating temperature by a heater to quickly converge to a target temperature in accordance with an environmental ambient temperature. An embodiment of a temperature control method comprises: a step (A) of obtaining, by means of PID control, a first energization rate y1 based on a first temperature difference e1 between an actually measured temperature Ta and a target temperature Ts; a step (B) of obtaining a second energization rate y2 based on a second temperature difference e2 between the ambient temperature Te of the environment in which a heating cylinder 2 is disposed and the target temperature Ts; a step (C) of obtaining a corrected energization rate y on the basis of the result of comparison of the first energization rate y1 and the second energization rate y2; and step (D) of controlling the electrical power to be supplied to a heater 4 on the basis of the corrected energization rate y. In step (C), the corrected energization rate y is set to any of predetermined first, second, and third conditions on the basis of the comparison result.

IPC Classes  ?

• G05D 23/19 - Control of temperature characterised by the use of electric means
• B29C 45/62 - Barrels or cylinders
• B29C 45/78 - Measuring, controlling or regulating of temperature

Abstract

Provided is an injection molding method for resin that contains reinforcing fiber, the method being capable of easily eliminating uneven distribution of added components. The injection molding method is provided with: a plasticizing step for supplying resin pellets P and added components to a cylinder equipped with a screw 10, which has a rotating axis as the center and is capable of rotating normally and in reverse, and generating molten resin by rotating the screw 10 in the normal direction; and an injection step for injecting the molten resin M comprising the added components into a cavity. In the plasticizing step, a reverse rotation operation for reversing the rotation of the screw 10 is performed or a screw-stopping operation of stopping the normal rotation of the screw 10 is performed with a prescribed timing and for a prescribed period.

IPC Classes  ?

• B29C 45/47 - Means for plasticising or homogenising the moulding material or forcing it into the mould using screws
• B29B 7/90 - Fillers or reinforcements
• B29C 45/54 - Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw
• B29C 45/76 - Measuring, controlling or regulating