A material supply device includes: an injection unit including a cylinder communicating with a nozzle and coupled to a flow path through which a plasticized material flows, and a plunger configured to move inside the cylinder, the injection unit being configured to perform a suction operation of suctioning the plasticized material from the flow path into the cylinder by moving the plunger rearward, and a feeding operation of feeding the plasticized material suctioned into the cylinder to the nozzle by moving the plunger forward. The plunger includes, in a longitudinal direction of the plunger, at least one first portion made of a material containing metal and a second portion made of a material containing a resin, a gap between the second portion and the cylinder is smaller than a gap between the first portion and the cylinder, and in the suction operation, when the plunger moves most rearward, the second portion is located within the cylinder.

An injection device of an injection molding machine includes an injection cylinder, a plunger, and a seal cylinder. The seal cylinder has a seal surface facing the plunger, a front surface forming a front surface flow path, and an outer side surface forming a side surface flow path. Between the injection cylinder and a side surface of the plunger, a first clearance is provided which is a gap that allows a molding material to flow through. Between the seal surface and the side surface of the plunger, a second clearance is provided which is a gap smaller than the first clearance and is reducible by a pressure of the molding material generated during dwelling.

A plasticizing device includes a material storage section having a first input port and a second input port and storing plasticization material; a plasticizing section having a supply port to which the plasticization material is supplied and plasticizing at least part of the plasticization material to generate a molding material; a connecting pipe having a connecting path connecting the first and the second input port to the supply port; and a controller, wherein the material storage section includes a first supply mechanism configured to adjust the supply amount of the plasticization material from the first input port to the connecting path and a second supply mechanism configured to adjust the supply amount of the plasticization material from the second input port to the connecting path and the controller controls at least one of the first and the second supply mechanism to supply the plasticization material to the connecting path.

A plasticizing device includes a material storage section having a first input port and a second input port and storing plasticization material; a plasticizing section having a supply port to which the plasticization material is supplied and plasticizing at least part of the plasticization material to generate a molding material; a connecting pipe having a connecting path connecting the first and the second input port to the supply port; and a controller, wherein the material storage section includes a first supply mechanism configured to adjust the supply amount of the plasticization material from the first input port to the connecting path and a second supply mechanism configured to adjust the supply amount of the plasticization material from the second input port to the connecting path and the controller controls at least one of the first and the second supply mechanism to supply the plasticization material to the connecting path.

After the injection shaft moves backward and the gas is supplied into the injection chamber, it is desired to accurately control the gas supply amount in the injection device in which the injection shaft is moved forward to compress and dissolve the gas in the molding material in the injection chamber. An injection device of the disclosure supplies a gas into an injection chamber via a gas supply hole which passes through an injection shaft and is opened at a tip surface of the injection shaft. The injection device of the disclosure has at least one seal ring and at least one piston ring aligned in an axial direction on an outer circumferential surface of the injection shaft.