Abstract: An injection molding machine includes: a cylinder that holds a molding material to be injected into a mold; a plasticizing member provided in the cylinder so as to be movable and rotatable; a temperature measurer that measures a temperature of the cylinder or of the mold; and a period setting unit configured to set a cold start prevention period, which is a period for restricting the injection of the molding material into the mold, based on the temperature measured by the temperature measurer until a temperature of the molding material or the temperature of the mold rises. The period setting unit stores temperature-time data in which the temperature measured by the temperature measurer is associated with time, and adjusts the cold start prevention period based on an actual temperature of the stored temperature-time data.

Abstract: A control method of an injection molding machine that molds a molding product including a skin layer and a core layer in a mold unit by injecting a molding material to the mold unit from a nozzle, the control method including controlling, at a starting time of an injection process, a temperature of the molding material used to form the skin layer so as to be higher than a temperature of the molding material used to form the core layer.

Abstract: An object is to reduce the axial dimension of an injection apparatus (31), facilitate the work of removing and inserting a screw (20), and improve the quality of molded products. The injection apparatus (31) comprises a heating cylinder (17), a screw (20), and a drive apparatus. The screw (20) includes a plasticizing portion which includes a body portion (45a) and a flight (53) projectingly formed on an outer circumferential surface of the body portion (45a). An index ?, which is obtained by dividing a value obtained by adding a screw stroke S and a screw effective length L together by the screw stroke S, satisfies the relation 2.0<?<4.5. Even when the screw (20) is shortened, resin can be melted satisfactorily. Accordingly, the axial dimension of the injection apparatus (31) can be reduced.

Abstract: An object is to reduce the axial dimension of an injection apparatus, melt a molding material uniformly, and improve the quality of molded products. A screw (20) comprises a plasticizing portion which comprises a body portion (45a) and a flight (53) projectingly formed on an outer circumferential surface of the body portion (45a). A groove-depth setting region is defined over a predetermined section of the plasticizing portion, and in the groove-depth setting region, the ratio ?1 of a groove depth ?1 to a diameter ?1 of pellets of a molding material falls within the range of 1??1?1.5 where the groove depth ?1 is a depth of a groove (67) formed along the flight (53). In the groove (67), pellets are arranged laterally and caused to advance while rolling along the groove (67). Since the pellets do not aggregate, no solid bed is formed.

Abstract: An object is to reduce the cost of a screw (20) and improve the quality of molded products. A rear end of the screw (20) is connected to a drive apparatus. The screw includes a screw head, a reverse-flow prevention apparatus, and a plasticizing member disposed rearward of the reverse-flow prevention apparatus. The plasticizing member includes a screw body (52), a flight (53) projectingly formed on an outer circumferential surface of the screw body (52), and a pressure member (54) formed to extend over a predetermined distance from the front end of the screw body (52) and to be located adjacent to the reverse-flow prevention apparatus. The pressure member (54) has a flat outer circumferential surface. Since the pressure member (54) has a flat outer circumferential surface having a diameter equal to or greater than the diameter of the screw body (52), the shape of the screw (20) can be simplified, and the cost of the screw (20) can be lowered.

Abstract: An object is to reduce the axial dimension of an injection apparatus, melt a molding material uniformly, and improve the quality of molded products. A screw (20) comprises a plasticizing portion which comprises a body portion (45a) and a flight (53) projectingly formed on an outer circumferential surface of the body portion (45a). A groove-depth setting region is defined over a predetermined section of the plasticizing portion, and in the groove-depth setting region, the ratio ?1 of a groove depth ?1 to a diameter ?1 of pellets of a molding material falls within the range of 1??1?1.5 where the groove depth ?1 is a depth of a groove (67) formed along the flight (53). In the groove (67), pellets are arranged laterally and caused to advance while rolling along the groove (67). Since the pellets do not aggregate, no solid bed is formed.

Abstract: An object is to reduce the axial dimension of an injection apparatus (31), facilitate the work of removing and inserting a screw (20), and improve the quality of molded products. The injection apparatus (31) comprises a heating cylinder (17), a screw (20), and a drive apparatus. The screw (20) includes a plasticizing portion which includes a body portion (45a) and a flight (53) projectingly formed on an outer circumferential surface of the body portion (45a). An index ?, which is obtained by dividing a value obtained by adding a screw stroke S and a screw effective length L together by the screw stroke S, satisfies the relation 2.0<?<4.5. Even when the screw (20) is shortened, resin can be melted satisfactorily. Accordingly, the axial dimension of the injection apparatus (31) can be reduced.

Abstract: An object is to reduce the cost of a screw (20) and improve the quality of molded products. A rear end of the screw (20) is connected to a drive apparatus. The screw includes a screw head, a reverse-flow prevention apparatus, and a plasticizing member disposed rearward of the reverse-flow prevention apparatus. The plasticizing member includes a screw body (52), a flight (53) projectingly formed on an outer circumferential surface of the screw body (52), and a pressure member (54) formed to extend over a predetermined distance from the front end of the screw body (52) and to be located adjacent to the reverse-flow prevention apparatus. The pressure member (54) has a flat outer circumferential surface. Since the pressure member (54) has a flat outer circumferential surface having a diameter equal to or greater than the diameter of the screw body (52), the shape of the screw (20) can be simplified, and the cost of the screw (20) can be lowered.

Abstract: The object of the present invention is to provide a molding method, a purging method, and a molding machine which can remove resin adhering to the rear surface of a flight of a screw with certainty. A molding material is supplied into a heating cylinder, a screw is rotated in one rotational direction, the pressing force of the molding material is applied to the front surface of the screw flight, the molding material is transported to the front of the screw while melting, the screw is rotated in the opposite rotational direction, the pressing force of the molding material is applied to the rear surface of the screw flight, and a reverse back pressure is applied to the screw.