Patent Description:
An injection unit for injecting a molten resin into a mold unit is known.

<CIT> discloses an injection unit including a first cylinder, a first movable unit that moves a molding material inside the first cylinder, a second cylinder to which the molding material is supplied from the first cylinder, a second movable unit that moves the molding material inside the second cylinder, a nozzle that injects a molding material into a mold unit, and a switching unit that switches flow directions of the molding material among the first cylinder, the second cylinder, and the nozzle. <CIT> discloses an in-line compounding and molding process for making fiber reinforced polypropylene composite parts and articles that exhibit beneficial mechanical and aesthetic properties imparted by such process and compositions. <CIT> discloses an injection device which is provided with a flow path switching block. <CIT> discloses an injection molding apparatus for use for articles made from synthetic hygroscopic synthetic resinous materials. <CIT> discloses an injection unit for harmonizing an operation of a first movable section with an operation of a second movable section.

Incidentally, in an injection molding machine system that supplies a molten resin as a molding material to an injection unit, an extruder can be used as a molten resin supply device. Here, the extruder continuously supplies the molten resin. Therefore, there is a possibility that the molten resin may overflow in the injection unit.

Therefore, an object of the present invention is to provide an injection molding machine capable of supplying a molten resin.

According to an aspect of an embodiment, there is provided an injection molding machine including an injection unit which includes a reservoir cylinder and an injection cylinder and to which a molten resin is supplied, a supply unit that supplies the molten resin to the reservoir cylinder and the injection cylinder, a discharge unit that discharges the molten resin supplied to the injection unit, a nozzle that injects the molten resin supplied to the injection cylinder into a mold unit, a control unit that controls the injection unit, a switching unit that switches flow directions of the molten resin among a supply/discharge switching unit, the injection cylinder, and the nozzle, and the supply/discharge switching unit that switches flow directions of the molten resin among the supply unit, the reservoir cylinder, the switching unit, and the discharge unit. The control unit has a determination unit that determines whether or not the molten resin is capable of being received in the injection cylinder, and a processing unit that controls the supply/discharge switching unit such that the flow direction of the molten resin is switched, based on a determination result of the determination unit.

According to the present invention, it is possible to provide the injection molding machine capable of supplying the molten resin.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In each drawing, the same or corresponding reference numerals will be assigned to the same or corresponding configurations, and description thereof will be omitted.

An injection molding machine system S according to a first embodiment will be described with reference to <FIG> is a configuration diagram of the injection molding machine system S according to the first embodiment.

The injection molding machine system S includes an injection molding machine <NUM>, a molten resin supply device <NUM>, a molten resin supply path <NUM>, and a control valve <NUM>.

The injection molding machine <NUM> includes a mold clamping unit <NUM> that opens and closes a mold unit (not illustrated), an injection unit <NUM> that injects a molding material into a cavity space of the mold unit, an ejector unit (not illustrated) that ejects a molding product molded by the mold unit, a moving unit (not illustrated) that advances and retreats the injection unit <NUM> with respect to the mold unit, a control unit <NUM> that controls each component of the injection molding machine <NUM>, and a frame <NUM> that supports each component of the injection molding machine <NUM>.

The mold clamping unit <NUM> performs a mold closing process, a pressurizing process, a mold clamping process, a depressurizing process, and a mold opening process under the control of the control unit <NUM>. In the mold closing process, the control unit <NUM> controls the mold clamping unit <NUM> so that a movable mold touches a stationary mold. In the pressurizing process, the control unit <NUM> controls the mold clamping unit <NUM> to generate a mold clamping force. In the mold clamping process, the control unit <NUM> controls the mold clamping unit <NUM> to maintain the mold clamping force generated in the pressurizing process. In the depressurizing process, the control unit <NUM> controls the mold clamping unit <NUM> to reduce the mold clamping force. In the mold opening process, the control unit <NUM> controls the mold clamping unit <NUM> so that the movable mold is separated from the stationary mold.

The injection unit <NUM> performs a plasticizing process, a filling process, and a holding pressure process under the control of the control unit <NUM>. The filling process and the holding pressure process may be collectively referred to as an injection process. In the plasticizing process, the control unit <NUM> controls the injection unit <NUM> so that a predetermined amount of a molten resin is accumulated in front of a second plunger <NUM> (refer to <FIG> (to be described later)). In the filling process, the control unit <NUM> controls the injection unit <NUM> to fill the cavity space inside the mold unit with the molten resin accumulated in front of the second plunger <NUM>. In the holding pressure process, the control unit <NUM> controls the injection unit <NUM> so that the second plunger <NUM> is pushed forward, a pressure (holding pressure) of the molding material is held at a setting pressure in a front end portion of the second plunger <NUM>, and the molten resin remaining inside an injection cylinder <NUM> (refer to <FIG> (to be described later)) is pushed toward the mold unit. In the injection molding machine <NUM>, a cooling process starts after the holding pressure process. In the cooling process, the molding material inside the cavity space is solidified. In order to shorten a molding cycle time, the plasticizing process may be performed during the cooling process.

The ejector unit (not illustrated) performs an ejection process under the control of the control unit <NUM>. In the ejection process, the control unit <NUM> controls the ejector unit so that an ejector rod (not illustrated) is advanced from a standby position to an ejection position to eject the molding product. Thereafter, the ejector rod is retreated to an original standby position.

The moving unit (not illustrated) advances and retreats the injection unit <NUM> with respect to the mold unit. The injection unit <NUM> is advanced toward the mold unit so that a nozzle <NUM> of the injection unit <NUM> is pressed against the stationary mold of the mold unit. The injection unit <NUM> is retreated so that the nozzle <NUM> of the injection unit <NUM> is separated from the stationary mold of the mold unit.

The control unit <NUM> repeatedly performs the plasticizing process, the mold closing process, the pressurizing process, the mold clamping process, the filling process, the holding pressure process, the cooling process, the depressurizing process, the mold opening process, and the ejection process, thereby repeatedly manufacturing the molding product. A series of operations for obtaining the molding product, for example, an operation from the start of the plasticizing process to the start of the subsequent plasticizing process will be referred to as a "shot" or a "molding cycle". In addition, a time required for one shot will be referred to as a "molding cycle time" or a "cycle time".

For example, in one molding cycle, the plasticizing process, the mold closing process, the pressurizing process, the mold clamping process, the filling process, the holding pressure process, the cooling process, the depressurizing process, the mold opening process, and the ejection process are performed in this order. The order described here is the order of the start times of the respective processes. The filling process, the holding pressure process, and the cooling process are performed during the mold clamping process. The start of the mold clamping process may coincide with the start of the filling process. Completion of the depressurizing process coincides with start of the mold opening process.

A plurality of processes may be performed at the same time in order to shorten the molding cycle time. For example, the plasticizing process may be performed during the cooling process of the previous molding cycle or may be performed during the mold clamping process. In this case, the mold closing process may be performed in an initial stage of the molding cycle. In addition, the filling process may start during the mold closing process. In addition, the ejection process may start during the mold opening process. When an on-off valve (not illustrated) for opening and closing a flow path of the nozzle <NUM> (refer to <FIG> (to be described later)) of the injection unit <NUM> is provided, the mold opening process may start during the plasticizing process. The reason is as follows. Even when the mold opening process starts during the plasticizing process, when the on-off valve (not illustrated) closes the flow path of the nozzle <NUM> of the injection unit <NUM>, the molding material does not leak from the nozzle <NUM> of the injection unit <NUM>.

One molding cycle may include a process other than the plasticizing process, the mold closing process, the pressurizing process, the mold clamping process, the filling process, the holding pressure process, the cooling process, the depressurizing process, the mold opening process, and the ejection process.

The molten resin supply device <NUM> is a device that supplies the molten resin (molding material). For example, the molten resin supply device <NUM> may be an extruder that melts and extrudes a solid molding material (for example, pellets).

The molten resin supply path <NUM> is a flow path that supplies the molten resin from the molten resin supply device <NUM> to the injection unit <NUM>. For example, the molten resin supply path <NUM> may include a pipe through which the molten resin flows, an insulation material for covering the pipe, and a heater for warming the molten resin flowing inside the pipe.

The control valve <NUM> is provided in the molten resin supply path <NUM>, and controls supply of the molten resin to the injection unit <NUM>. For example, the control valve <NUM> may be an on-off valve. The control valve <NUM> is controlled by the control unit <NUM> (control unit <NUM> (to be described later)) of the injection molding machine <NUM>.

The injection molding machine system S according to the first embodiment is illustrated by using a configuration in which one injection molding machine <NUM> is connected to the molten resin supply path <NUM>. However, the present invention is not limited thereto, and a configuration may be adopted so that a plurality of the injection molding machines <NUM> are connected to the molten resin supply path <NUM>. In addition, the injection molding machine system S according to the first embodiment is illustrated by using a configuration in which one molten resin supply device <NUM> is connected to the molten resin supply path <NUM>. However, the present invention is not limited thereto, and a configuration may be adopted so that a plurality of the molten resin supply devices <NUM> are connected to the molten resin supply path <NUM>.

Next, the injection unit <NUM> of the injection molding machine <NUM> according to the first embodiment will be further described with reference to <FIG> is a schematic sectional view of the injection unit <NUM> according to the first embodiment. <FIG> is a sectional view perpendicular to a rotation center line of a valve body <NUM>.

The injection unit <NUM> includes a reservoir cylinder (first cylinder) <NUM>, a first plunger (first movable unit) <NUM>, a first plunger drive unit (first drive unit) <NUM>, an injection cylinder (second cylinder) <NUM>, a second plunger (second movable unit) <NUM>, a second plunger drive unit (second drive unit) <NUM>, a molten resin supply unit (supply unit) <NUM>, a connecting portion <NUM>, the nozzle <NUM>, a direction switching valve (switching unit) <NUM>, a discharge unit <NUM>, a discharge valve (supply/discharge switching unit) <NUM>, and a control unit (control unit) <NUM>(<NUM>).

A liquid molding material (molten resin) is supplied into the reservoir cylinder <NUM> from the molten resin supply unit <NUM>. A heating source such as a heater is provided on an outer periphery of the reservoir cylinder <NUM>.

The first plunger <NUM> is disposed inside the reservoir cylinder <NUM> to move the molding material inside the reservoir cylinder <NUM>. The first plunger <NUM> is disposed inside the reservoir cylinder <NUM> to be freely advanced and retreated.

The first plunger drive unit <NUM> operates the first plunger <NUM>. The first plunger drive unit <NUM> has an advancing and retreating motor <NUM>, an encoder <NUM>, and a pressure detector <NUM>.

The advancing and retreating motor <NUM> advances and retreats the first plunger <NUM>. A motion conversion mechanism for converting a rotary motion of the advancing and retreating motor <NUM> into a linear motion of the first plunger <NUM> is provided between the first plunger <NUM> and the advancing and retreating motor <NUM>. For example, the motion conversion mechanism is configured to include a ball screw.

The encoder <NUM> detects the rotation of the advancing and retreating motor <NUM>, and transmits a signal indicating a detection result thereof to the control unit <NUM>. The control unit <NUM> calculates a position and a movement speed of the first plunger <NUM>, based on a detection value of the encoder <NUM>. The detection result of the encoder <NUM> is used in controlling or monitoring the position of the first plunger <NUM> or the movement speed of the first plunger <NUM>.

The pressure detector <NUM> is provided in a force transmission channel between the advancing and retreating motor <NUM> and the first plunger <NUM>, detects a force transmitted between the advancing and retreating motor <NUM> and the first plunger <NUM>, and transmits a signal indicating a detection result thereof to the control unit <NUM>. The detected force is converted into a pressure of the first plunger <NUM> by the control unit <NUM>. The detection result of the pressure detector <NUM> is used in controlling or monitoring the pressure received from the molding material by the first plunger <NUM>, a back pressure with respect to the first plunger <NUM>, or the pressure acting on the molding material from the first plunger <NUM>.

The molding material is supplied into the injection cylinder <NUM> from the molten resin supply unit <NUM> and the reservoir cylinder <NUM>. A heating source such as a heater is provided on the outer periphery of the injection cylinder <NUM>.

The second plunger <NUM> is disposed inside the injection cylinder <NUM> to moves the molding material inside the injection cylinder <NUM>. The second plunger <NUM> is disposed inside the injection cylinder <NUM> to be freely advanced and retreated.

The second plunger drive unit <NUM> operates the second plunger <NUM>. The second plunger drive unit <NUM> has an advancing and retreating motor <NUM>.

The advancing and retreating motor <NUM> advances and retreats the second plunger <NUM>. A motion conversion mechanism for converting a rotary motion of the advancing and retreating motor <NUM> into a linear motion of the second plunger <NUM> is provided between the second plunger <NUM> and the advancing and retreating motor <NUM>. For example, the motion conversion mechanism is configured to include a ball screw.

The encoder <NUM> detects the rotation of the advancing and retreating motor <NUM>, and transmits a signal indicating a detection result thereof to the control unit <NUM>. The control unit <NUM> calculates the position and movement speed of the second plunger <NUM>, based on a detection value of the encoder <NUM>. The detection result of the encoder <NUM> is used for controlling or monitoring the position of the second plunger <NUM> or the movement speed of the second plunger <NUM>.

The pressure detector <NUM> is provided in a force transmission channel between the advancing and retreating motor <NUM> and the second plunger <NUM>, detects a force transmitted between the advancing and retreating motor <NUM> and the second plunger <NUM>, and transmits a signal indicating the detection result to the control unit <NUM>. The detected force is converted into the pressure of the second plunger <NUM> by the control unit <NUM>. The detection result of the pressure detector <NUM> is used in controlling or monitoring the pressure received from the molding material by the second plunger <NUM>, a back pressure with respect to the second plunger <NUM>, or the pressure acting on the molding material from the second plunger <NUM>.

The molten resin supply unit <NUM> is connected to the molten resin supply path <NUM> (refer to <FIG>), and the molten resin is continuously supplied from the molten resin supply device <NUM>.

The connecting portion <NUM> connects the molten resin supply unit <NUM>, the reservoir cylinder <NUM>, and the direction switching valve <NUM> so that the molten resin can flow therethrough.

The nozzle <NUM> injects the molding material supplied from the direction switching valve <NUM> into the mold unit. The liquid molding material filled inside the mold unit is solidified, and the molding product is molded.

The direction switching valve <NUM> switches flow directions of the molding material among the connecting portion <NUM> (reservoir cylinder <NUM>, molten resin supply unit <NUM>), the injection cylinder <NUM>, and the nozzle <NUM>. The direction switching valve <NUM> has a valve casing <NUM>, a valve body <NUM>, and a valve body drive unit (not illustrated).

The valve casing <NUM> has a supply side connection port <NUM>, an injection cylinder connection port <NUM>, and a nozzle connection port <NUM>. The supply side connection port <NUM> communicates with the inside of the molten resin supply unit <NUM> and the reservoir cylinder <NUM>. The injection cylinder connection port <NUM> communicates with the inside of the injection cylinder <NUM>. The nozzle connection port <NUM> communicates with the inside of the nozzle <NUM>.

For example, the injection cylinder connection port <NUM> and the nozzle connection port <NUM> are provided on sides opposite to each other across a rotation center line of the valve body <NUM>. On the other hand, for example, the supply side connection port <NUM> is provided at a position substantially equidistant along the outer periphery of the valve body <NUM> from both the injection cylinder connection port <NUM> and the nozzle connection port <NUM>. That is, the injection cylinder connection port <NUM>, the supply side connection port <NUM>, and the nozzle connection port <NUM> are disposed at a <NUM>° pitch in this order in a predetermined direction (counterclockwise in <FIG>) around the rotation center line of the valve body <NUM>.

The valve body <NUM> is rotated inside the valve casing <NUM> to switch between a first state (refer to <FIG> (to be described later)) and a second state (refer to <FIG>). In the first state, the valve body <NUM> causes the supply side connection port <NUM> and the injection cylinder connection port <NUM> to communicate with each other, and closes the nozzle connection port <NUM>. On the other hand, in the second state, the valve body <NUM> causes the injection cylinder connection port <NUM> and the nozzle connection port <NUM> to communicate with each other, and closes the supply side connection port <NUM>. In this manner, in the first state, the molten resin is suppliable to the injection cylinder <NUM> from the molten resin supply unit <NUM> and reservoir cylinder <NUM>. In the second state, the molten resin is suppliable to the nozzle <NUM> from the injection cylinder <NUM>.

A state of the valve body <NUM> is not limited to the first state and the second state. For example, the valve body <NUM> may be in a state of simultaneously closing the supply side connection port <NUM>, the injection cylinder connection port <NUM>, and the nozzle connection port <NUM>. In addition, the valve body <NUM> may be in a state where the supply side connection port <NUM> and the nozzle connection port <NUM> communicate with each other and the injection cylinder connection port <NUM> is closed.

The valve body drive unit operates the valve body <NUM>. Specifically, the valve body drive unit switches between the first state and the second state by rotating the valve body <NUM> inside the valve casing <NUM>.

The discharge unit <NUM> discharges the molten resin outward of the injection unit <NUM>.

The discharge valve <NUM> is a valve for opening and closing the discharge unit <NUM>. In an example illustrated in <FIG>, the discharge valve <NUM> is configured to serve as a direction switching valve. The discharge valve <NUM> switches flow directions of the molding material among the molten resin supply unit <NUM>, the reservoir cylinder <NUM>, the connecting portion <NUM> (direction switching valve <NUM>), and the discharge unit <NUM>. The discharge valve <NUM> has a valve casing <NUM>, a valve body <NUM>, and a valve body drive unit (not illustrated).

The valve casing <NUM> has connection ports <NUM> to <NUM>. The connection port <NUM> communicates with the inside of the molten resin supply unit <NUM>. The connection port <NUM> communicates with the inside of the reservoir cylinder <NUM>. The connection port <NUM> communicates with the inside of the connecting portion <NUM>. The connection port <NUM> communicates with the inside of the discharge unit <NUM>. In the connection ports <NUM> to <NUM>, the connection port <NUM>, the connection port <NUM>, the connection port <NUM>, and the connection port <NUM> are disposed at a <NUM>° pitch in this order in a predetermined direction (clockwise in <FIG>) around the rotation center line of the valve body <NUM>. In addition, the connection ports <NUM> to <NUM> serve as supply paths for supplying the molten resin from the molten resin supply unit <NUM> to the cylinder (reservoir cylinder <NUM> and/or the injection cylinder <NUM>). The connection port <NUM> serves as a discharge path for discharging the molten resin from the molten resin supply unit <NUM> to the discharge unit <NUM>.

The valve body <NUM> is rotated inside the valve casing <NUM> to switch between the first state (refer to <FIG> (to be described later)) and the second state (refer to <FIG> (to be described later)). In the first state, the valve body <NUM> causes the connection ports <NUM> to <NUM> to communicate with each other, and closes the connection port <NUM>. On the other hand, in the second state, the valve body <NUM> causes the connection ports <NUM>, <NUM>, and <NUM> to communicate with each other, and closes the connection port <NUM>.

A state of the valve body <NUM> is not limited to the first state and the second state. For example, the valve body <NUM> may be in a state where the connection ports <NUM>, <NUM>, and <NUM> communicate with each other and the connection port <NUM> is closed. In addition, the valve body <NUM> may be in a state where the connection ports <NUM> to <NUM> communicate with each other and the connection port <NUM> is closed.

The control unit <NUM> controls the first plunger drive unit <NUM>, the second plunger drive unit <NUM>, the direction switching valve <NUM>, and the discharge valve <NUM>. The control unit <NUM> may be configured to serve as a portion of the control unit <NUM> that controls each component of the injection molding machine <NUM>. In addition, the control unit <NUM> may be provided separately from the control unit <NUM>.

The control unit <NUM> has a determination unit <NUM>, a processing unit <NUM>, and a flow path switching processing unit <NUM>. The determination unit <NUM> determines whether or not the molten resin is suppliable to the injection unit <NUM>. That is, the determination unit <NUM> determines whether or not the molten resin can be received in the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>) of the injection unit <NUM>. The processing unit <NUM> processes the supply of the molten resin on the determination result of the determination unit <NUM>. The flow path switching processing unit <NUM> controls the first plunger drive unit <NUM>, the second plunger drive unit <NUM>, and the direction switching valve <NUM> to control a flow of the molten resin.

Next, an operation of the injection unit <NUM> according to the first embodiment will be described with reference to <FIG>. <FIG> is a flowchart illustrating the operation of the injection unit <NUM> according to the first embodiment. In describing the operation illustrated in a flow of <FIG>, the valve body <NUM> of the discharge valve <NUM> is in the first state. In addition, in <FIG> (and <FIG> (to be described later)), the flow of the molten resin is indicated by a broken line arrow, and moving directions of the first plunger <NUM> and the second plunger <NUM> are indicated by shaded arrows. In the flowchart illustrated in <FIG>, an example will be described in which the determination unit <NUM> determines that the molten resin is suppliable to the injection unit <NUM>.

<FIG> is a view illustrating a state of the injection unit <NUM> according to the first embodiment in the plasticizing process. In Step S101, the flow path switching processing unit <NUM> of the control unit <NUM> performs the plasticizing process. The flow path switching processing unit <NUM> of the control unit <NUM> controls a valve body drive unit of the direction switching valve <NUM> so that the valve body <NUM> of the direction switching valve <NUM> is brought into the first state. The molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM> via the molten resin supply unit <NUM>, the discharge valve <NUM>, the connecting portion <NUM>, and the direction switching valve <NUM>. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> drives the advancing and retreating motor <NUM> to advance the first plunger <NUM>. The molten resin accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> is accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM> via the discharge valve <NUM>, the connecting portion <NUM>, and the direction switching valve <NUM>.

The molten resin is accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM>. In this manner, the second plunger <NUM> inside the injection cylinder <NUM> is retreated. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the second plunger <NUM>, based on a detection value of the encoder <NUM>. Here, in order to suppress sudden retreat of the second plunger <NUM>, the flow path switching processing unit <NUM> of the control unit <NUM> may drive the advancing and retreating motor <NUM>, based on a detection value of the pressure detector <NUM>, and a set back pressure may be applied to the second plunger <NUM>.

<FIG> is a view illustrating a state of the injection unit <NUM> according to the first embodiment after the plasticizing process is completed. When the second plunger <NUM> is retreated to a predetermined position and a predetermined amount of the molten resin is accumulated in front of the second plunger <NUM>, the flow path switching processing unit <NUM> of the control unit <NUM> stops driving the advancing and retreating motor <NUM>, and stops driving the advancing and retreating motor <NUM>. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the direction switching valve <NUM> so that the valve body <NUM> of the direction switching valve <NUM> is brought into the second state. The molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the discharge valve <NUM>. The molten resin is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM>. In this manner, the first plunger <NUM> inside the reservoir cylinder <NUM> is retreated. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the first plunger <NUM>, based on a detection value of the encoder <NUM>. Here, in order to suppress sudden retreat of the first plunger <NUM>, the flow path switching processing unit <NUM> of the control unit <NUM> may drive the advancing and retreating motor <NUM>, based on a detection value of the pressure detector <NUM>, and a set back pressure may be applied to the first plunger <NUM>. A process in which the valve body <NUM> of the direction switching valve <NUM> is brought into the second state and the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> will be referred to as a reservoir plunger plasticizing process.

<FIG> is a view illustrating a state of the injection unit <NUM> according to the first embodiment in the filling process. In Step S102, the flow path switching processing unit <NUM> of the control unit <NUM> performs the filling process. The flow path switching processing unit <NUM> of the control unit <NUM> drives the advancing and retreating motor <NUM> to advance the second plunger <NUM> to a predetermined position. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the second plunger <NUM>, based on a detection value of the encoder <NUM>. The cavity space inside the mold unit is filled with the molten resin accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM> via the direction switching valve <NUM> and the nozzle <NUM>. In addition, in the filling process, the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the discharge valve <NUM> (reservoir plunger plasticizing process).

<FIG> is a view illustrating a state of the injection unit <NUM> according to the first embodiment in the holding pressure process. In Step S103, the flow path switching processing unit <NUM> of the control unit <NUM> performs the holding pressure process. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the advancing and retreating motor <NUM>, based on a detection value of the pressure detector <NUM>, so that the second plunger <NUM> is pushed forward, a pressure (holding pressure) of the molten resin is held at a setting pressure in the front end portion of the second plunger <NUM>, and the molten resin remaining inside the injection cylinder <NUM> is pushed toward the mold unit. In addition, in the holding pressure process, the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the discharge valve <NUM> (reservoir plunger plasticizing process). In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the first plunger <NUM>, based on a detection value of the encoder <NUM>.

After the holding pressure process is completed and before the molding material is supplied from the reservoir cylinder <NUM> to the injection cylinder <NUM> in the subsequent plasticizing process, the flow path switching processing unit <NUM> of the control unit <NUM> rotates the valve body <NUM> of the direction switching valve <NUM>, and returns a state of the valve body <NUM> from the second state illustrated in <FIG> to the first state illustrated in <FIG>.

The flow path switching processing unit <NUM> of the control unit <NUM> repeatedly performs the plasticizing process, the filling process, and the holding pressure process so that the injection molding machine <NUM> repeatedly manufactures the molding products.

In other words, the control unit <NUM> of the injection unit <NUM> according to the first embodiment repeatedly performs the reservoir plunger plasticizing process of supplying the molten resin from the molten resin supply unit <NUM> to the reservoir cylinder <NUM> and accumulating the molten resin in the reservoir cylinder <NUM>, the plasticizing process of supplying the molten resin from the molten resin supply unit <NUM> and the reservoir cylinder <NUM> to the injection cylinder <NUM> and accumulating the molten resin in the injection cylinder <NUM>, the filling process of filling the cavity space inside the mold unit with the molten resin from the injection cylinder <NUM>, and the holding pressure process of holding the pressure of the molten resin at the setting pressure. In addition, during the injection process (filling process and holding pressure process), the reservoir plunger plasticizing process of the subsequent molding cycle is performed at the same time.

As described above, according to the injection unit <NUM> in the first embodiment, the injection unit <NUM> is used for the injection molding machine system S in which the molten resin is continuously supplied to the molten resin supply unit <NUM> from the molten resin supply device <NUM>. In the reservoir plunger plasticizing process, the molten resin can be accumulated in the reservoir cylinder <NUM>. Accordingly, the overflow of the molten resin can be prevented.

Next, an operation of the discharge valve <NUM> of the injection unit <NUM> according to the first embodiment will be described with reference to <FIG>. <FIG> is a flowchart illustrating the operation of the discharge valve <NUM> in the injection unit <NUM> according to the first embodiment. When a flow of <FIG> starts, the valve body <NUM> of the discharge valve <NUM> is in the first state.

In Step S201, the determination unit <NUM> of the control unit <NUM> determines whether or not the direction switching valve <NUM> is in the second state. When the direction switching valve <NUM> is not in the second state (S201: No), in the process of the control unit <NUM>, Step S201 is repeatedly performed. When the direction switching valve <NUM> is in the second state (S201: Yes), the process of the control unit <NUM> proceeds to Step S202.

In Step S202, the determination unit <NUM> of the control unit <NUM> determines whether or not a supply stop condition is satisfied. Here, when the supply stop condition is satisfied, the determination unit <NUM> determines that the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>) of the injection unit <NUM> cannot receive the molten resin. The supply stop condition is a condition for stopping the supply of the molten resin to the reservoir cylinder <NUM> from the molten resin supply unit <NUM>. In other words, the supply stop condition is a condition for discharging the molten resin supplied from the molten resin supply unit <NUM> from the discharge unit <NUM>. For example, the determination unit <NUM> of the control unit <NUM> causes the encoder <NUM> to detect a position of the first plunger <NUM>, and determines that the supply stop condition is satisfied when the first plunger <NUM> is retreated to a predetermined position (for example, a retreat limit). The reason is as follows. When the first plunger <NUM> is retreated to the predetermined position, remaining capacity that can be accumulated in the reservoir cylinder <NUM> decreases, thereby causing a possibility that the molten resin may overflow from the reservoir cylinder <NUM>. In addition, when a cycle time exceeds a predetermined time, the determination unit <NUM> of the control unit <NUM> may determine that the supply stop condition is satisfied. The molten resin is supplied to the reservoir cylinder <NUM>. With the lapse of time, the molten resin accumulated in the reservoir cylinder <NUM> increases. The reason is as follows. When the cycle time exceeds the predetermined time, the remaining capacity that can be accumulated in the reservoir cylinder <NUM> decreases, thereby causing a possibility that the molten resin may overflow from the reservoir cylinder <NUM>. In addition, the determination unit <NUM> of the control unit <NUM> may determine whether or not the supply stop condition is satisfied, based on a detection value of the pressure detector <NUM>. When the supply stop condition is not satisfied (S202: No), the process of the control unit <NUM> returns to Step S201. When the supply stop condition is satisfied (S202: Yes), the process of the control unit <NUM> proceeds to Step S203.

<FIG> is a view illustrating a state of the injection unit <NUM> according to the first embodiment in which the discharge valve <NUM> is in the second state. In Step S203, the processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the discharge valve <NUM> so that the valve body <NUM> of the discharge valve <NUM> is brought into the second state. The molten resin supplied from the molten resin supply unit <NUM> is discharged outward of the injection unit <NUM> from the discharge unit <NUM> via the molten resin supply unit <NUM> and the discharge valve <NUM>.

In Step S204, the determination unit <NUM> of the control unit <NUM> determines whether or not the operation of the injection unit <NUM> starts the plasticizing process (refer to Step S101 in <FIG>). When the plasticizing process does not start (S204: No), the process of the control unit <NUM> returns to Step S203. When the plasticizing process starts (S204: Yes), the process of the control unit <NUM> proceeds to Step S205.

In Step S205, the processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the discharge valve <NUM> so that the valve body <NUM> of the discharge valve <NUM> is brought into the first state. Then, the process of the control unit <NUM> returns to Step S201.

In this way, according to the injection unit <NUM> in the first embodiment, when it is determined that the injection unit <NUM> of the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>) cannot receive the molten resin, the molten resin supplied from the molten resin supply unit <NUM> is discharged outward of the injection unit <NUM> from the discharge unit <NUM>. In this manner, it is possible to prevent the molten resin from overflowing in the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>), and it is possible to prevent damage to the injection unit <NUM>.

Next, an injection unit 3A of an injection molding machine according to a second embodiment will be described with reference to <FIG> is a schematic sectional view of the injection unit 3A according to the second embodiment. <FIG> is a sectional view perpendicular to the rotation center line of the valve body <NUM>.

The injection unit 3A according to the second embodiment illustrated in <FIG> is different from the injection unit <NUM> according to the first embodiment illustrated in <FIG> in that a supply/discharge valve 70A is provided instead of the discharge valve <NUM>. Specifically, the connection of the flow path in the valve body 72A is different. Other configurations are the same as those of the injection unit <NUM> according to the first embodiment, and repeated description will be omitted.

The supply/discharge valve 70A is a valve for switching between the supply and the discharge of the molten resin. In an example illustrated in <FIG>, the supply/discharge valve 70A is configured to serve as the direction switching valve. The supply/discharge valve 70A switches flow directions of the molding material among the molten resin supply unit <NUM>, the reservoir cylinder <NUM>, the connecting portion <NUM> (direction switching valve <NUM>), and the discharge unit <NUM>. The supply/discharge valve 70A has the valve casing <NUM>, a valve body 72A, and a valve body drive unit (not illustrated).

The valve body 72A is rotated inside the valve casing <NUM> to switch between the first state (refer to <FIG> (to be described later)) and the second state (refer to <FIG> and <FIG> (to be described later)). In the first state, the valve body 72A causes the connection port <NUM> and the connection port <NUM> to communicate with each other, and causes the connection port <NUM> and the connection port <NUM> to communicate with each other. On the other hand, in the second state, the valve body 72A causes the connection port <NUM> and the connection port <NUM> to communicate with each other, and causes the connection port <NUM> and the connection port <NUM> to communicate with each other. In this manner, in the first state, the molten resin can be supplied to the reservoir cylinder <NUM> from the molten resin supply unit <NUM>. In the second state, the molten resin can be supplied to the injection cylinder <NUM> from the reservoir cylinder <NUM>, and the molten resin can be discharged to the discharge unit <NUM> from the molten resin supply unit <NUM>.

The valve body drive unit operates the valve body 72A. Specifically, the valve body drive unit switches between the first state and the second state by rotating the valve body 72A inside the valve casing <NUM>.

Next, an operation of the injection unit 3A according to the second embodiment will be described with reference to <FIG> while referring to <FIG>. In <FIG> (and <FIG> (to be described later)), a flow of the molten resin is indicated by a broken line arrow, and moving directions of the first plunger <NUM> and the second plunger <NUM> are indicated by shaded arrows. In addition, in the flowchart illustrated in <FIG>, an example will be described in which the determination unit <NUM> determines that the molten resin is suppliable to the injection unit 3A.

<FIG> is a view illustrating a state of the injection unit 3A according to the second embodiment in the plasticizing process. In Step S101, the flow path switching processing unit <NUM> of the control unit <NUM> performs the plasticizing process. The flow path switching processing unit <NUM> of the control unit <NUM> controls a valve body drive unit of the direction switching valve <NUM> so that the valve body <NUM> of the direction switching valve <NUM> is brought into the first state. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the supply/discharge valve 70A so that the valve body 72A of the supply/discharge valve 70A is brought into the second state. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> drives the advancing and retreating motor <NUM> to advance the first plunger <NUM>. The molten resin accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> is accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM> via the supply/discharge valve 70A, the connecting portion <NUM>, and the direction switching valve <NUM>. On the other hand, the molten resin supplied from the molten resin supply unit <NUM> is discharged outward of the injection unit <NUM> from the discharge unit <NUM> via the molten resin supply unit <NUM> and the supply/discharge valve 70A.

<FIG> is a view illustrating a state of the injection unit 3A according to the second embodiment after the plasticizing process is completed. When the second plunger <NUM> is retreated to a predetermined position and a predetermined amount of the molten resin is accumulated in front of the second plunger <NUM>, the flow path switching processing unit <NUM> of the control unit <NUM> stops driving the advancing and retreating motor <NUM>, and stops driving the advancing and retreating motor <NUM>. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the direction switching valve <NUM> so that the valve body <NUM> of the direction switching valve <NUM> is brought into the second state. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the supply/discharge valve 70A so that the valve body 72A of the supply/discharge valve 70A is brought into the first state. The molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the supply/discharge valve 70A. The molten resin is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM>. In this manner, the first plunger <NUM> inside the reservoir cylinder <NUM> is retreated. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the first plunger <NUM>, based on a detection value of the encoder <NUM>. Here, in order to suppress sudden retreat of the first plunger <NUM>, the flow path switching processing unit <NUM> of the control unit <NUM> may drive the advancing and retreating motor <NUM>, based on a detection value of the pressure detector <NUM>, and a set back pressure may be applied to the first plunger <NUM>. A process in which the valve body <NUM> of the direction switching valve <NUM> is brought into the second state and the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> will be referred to as a reservoir plunger plasticizing process.

<FIG> is a view illustrating a state of the injection unit 3A according to the second embodiment in the filling process. In Step S102, the flow path switching processing unit <NUM> of the control unit <NUM> performs the filling process. The flow path switching processing unit <NUM> of the control unit <NUM> drives the advancing and retreating motor <NUM> to advance the second plunger <NUM> to a predetermined position. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the second plunger <NUM>, based on a detection value of the encoder <NUM>. The cavity space inside the mold unit is filled with the molten resin accumulated in front of the second plunger <NUM> inside the injection cylinder <NUM> via the direction switching valve <NUM> and the nozzle <NUM>. In addition, in the filling process, the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the supply/discharge valve 70A (reservoir plunger plasticizing process).

<FIG> is a view illustrating a state of the injection unit 3A according to the second embodiment in the holding pressure process. In Step S103, the flow path switching processing unit <NUM> of the control unit <NUM> performs the holding pressure process. In addition, the flow path switching processing unit <NUM> of the control unit <NUM> controls the advancing and retreating motor <NUM>, based on a detection value of the pressure detector <NUM>, so that the second plunger <NUM> is pushed forward, a pressure (holding pressure) of the molten resin is held at a setting pressure in the front end portion of the second plunger <NUM>, and the molten resin remaining inside the injection cylinder <NUM> is pushed toward the mold unit. In addition, in the holding pressure process, the molten resin supplied from the molten resin supply unit <NUM> is accumulated in front of the first plunger <NUM> inside the reservoir cylinder <NUM> via the molten resin supply unit <NUM> and the supply/discharge valve 70A (reservoir plunger plasticizing process). In addition, the flow path switching processing unit <NUM> of the control unit <NUM> detects a position of the first plunger <NUM>, based on a detection value of the encoder <NUM>.

After the holding pressure process is completed and before the molding material is supplied from the reservoir cylinder <NUM> to the injection cylinder <NUM> in the subsequent plasticizing process, the flow path switching processing unit <NUM> of the control unit <NUM> rotates the valve body <NUM> of the direction switching valve <NUM>, and returns a state of the valve body <NUM> from the second state illustrated in <FIG> to the first state illustrated in <FIG>. In addition, the valve body 72A of the supply/discharge valve 70A is rotated to return the state of the valve body 72A from the first state illustrated in <FIG> to the second state illustrated in <FIG>.

In other words, the control unit <NUM> of the injection unit 3A according to the second embodiment repeatedly performs the reservoir plunger plasticizing process of supplying the molten resin from the molten resin supply unit <NUM> to the reservoir cylinder <NUM> and accumulating the molten resin in the reservoir cylinder <NUM>, the plasticizing process of supplying the molten resin from the reservoir cylinder <NUM> to the injection cylinder <NUM> and accumulating the molten resin in the injection cylinder <NUM>, the filling process of filling the cavity space inside the mold unit with the molten resin from the injection cylinder <NUM>, and the holding pressure process of holding the pressure of the molten resin at the setting pressure. In addition, during the injection process (filling process and holding pressure process), the reservoir plunger plasticizing process of the subsequent molding cycle is performed at the same time.

As described above, according to the injection unit 3A in the second embodiment, the injection unit 3A is used for the injection molding machine system S in which the molten resin is continuously supplied to the molten resin supply unit <NUM> from the molten resin supply device <NUM>. In the reservoir plunger plasticizing process, the molten resin can be accumulated in the reservoir cylinder <NUM>. Accordingly, the overflow of the molten resin can be prevented. In addition, in the plasticizing process of supplying the molten resin from the reservoir cylinder <NUM> to the injection cylinder <NUM>, the molten resin is discharged outward of the injection unit 3A from the discharge unit <NUM>. In this manner, it is possible to prevent the molten resin from overflowing in the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>), and it is possible to prevent damage to the injection unit <NUM>.

Next, an operation of the supply/discharge valve 70A of the injection unit 3A according to the second embodiment will be described with reference to <FIG> while referring to <FIG>. <FIG> is a flowchart illustrating the operation of the supply/discharge valve 70A in the injection unit 3A according to the second embodiment.

In Step S301, the determination unit <NUM> of the control unit <NUM> determines whether or not a process of the injection unit 3A is the reservoir plunger plasticizing process. That is, it is determined whether or not the supply/discharge valve 70A is in the first state (refer to <FIG>), and the molten resin is supplied from the molten resin supply unit <NUM> to the reservoir cylinder <NUM>. When the process is not the reservoir plunger plasticizing process (S301: No), in the process of the control unit <NUM>, Step S301 is repeatedly performed. When the process is the reservoir plunger plasticizing process (S301: Yes), the process of the control unit <NUM> proceeds to Step S302.

In Step S302, the determination unit <NUM> of the control unit <NUM> determines whether or not the supply stop condition is satisfied. Here, when the supply stop condition is satisfied, the determination unit <NUM> determines that the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>) of the injection unit 3A cannot receive the molten resin. The supply stop condition is a condition for stopping the supply of the molten resin to the reservoir cylinder <NUM> from the molten resin supply unit <NUM>. In other words, the supply stop condition is a condition for discharging the molten resin supplied from the molten resin supply unit <NUM> from the discharge unit <NUM>. For example, the determination unit <NUM> of the control unit <NUM> causes the encoder <NUM> to detect a position of the first plunger <NUM>, and determines that the supply stop condition is satisfied when the first plunger <NUM> is retreated to a predetermined position (for example, a retreat limit). In addition, when a cycle time exceeds a predetermined time, the determination unit <NUM> of the control unit <NUM> may determine that the supply stop condition is satisfied. In addition, the determination unit <NUM> of the control unit <NUM> may determine whether or not the supply stop condition is satisfied, based on a detection value of the pressure detector <NUM>. When the supply stop condition is not satisfied (S302: No), the process of the control unit <NUM> returns to Step S301. When the supply stop condition is satisfied (S302: Yes), the process of the control unit <NUM> proceeds to Step S303.

<FIG> is a view illustrating a state of the injection unit 3A according to the second embodiment in which the supply/discharge valve 70A is in the second state. In Step S303, the processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the supply/discharge valve 70A so that the valve body 72A of the supply/discharge valve 70A is brought into the second state. The molten resin supplied from the molten resin supply unit <NUM> is discharged outward of the injection unit 3A from the discharge unit <NUM> via the molten resin supply unit <NUM> and the supply/discharge valve 70A.

In Step S304, the determination unit <NUM> of the control unit <NUM> determines whether or not the operation of the injection unit 3A starts the reservoir plunger plasticizing process. In other words, it is determined whether or not the plasticizing process S101 of supplying the molten resin to the injection cylinder <NUM> from the reservoir cylinder <NUM> is completed and the molten resin can be supplied from the molten resin supply unit <NUM> to the reservoir cylinder <NUM>. When the reservoir plunger plasticizing process does not start (S304: No), the process of the control unit <NUM> returns to Step S303. When the reservoir plunger plasticizing process starts (S304: Yes), the process of the control unit <NUM> proceeds to Step S305.

In Step S305, the processing unit <NUM> of the control unit <NUM> controls the valve body drive unit of the supply/discharge valve 70A so that the valve body 72A of the supply/discharge valve 70A is brought into the first state (refer to <FIG>). Then, the process of the control unit <NUM> returns to Step S301.

In this way, according to the injection unit 3A in the second embodiment, when it is determined that the cylinder of the injection unit 3A (reservoir cylinder <NUM> and/or injection cylinder <NUM>) cannot receive the molten resin, the molten resin supplied from the molten resin supply unit <NUM> is discharged outward of the injection unit 3A from the discharge unit <NUM>. In this manner, it is possible to prevent the molten resin from overflowing in the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>), and it is possible to prevent damage to the injection unit <NUM>.

Hitherto, the embodiments of the injection molding machine system S, the injection molding machine <NUM>, and the injection units <NUM> and 3A have been described. However, the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made within the scope of the present invention described in the appended claims.

An example has been described in which the direction switching valve <NUM> is a switching valve that switches the flow directions by rotating the valve body <NUM> inside the valve casing <NUM>. However, the present invention is not limited thereto. The direction switching valve <NUM> may be a switching valve that switches the flow directions by sliding the valve body inside the valve casing, or may be a switching valve that switches the flow directions by adopting another configuration. In addition, an example has been described in which the discharge valve <NUM> is a switching valve that switches the flow directions by rotating the valve body <NUM> inside the valve casing <NUM>. However, the present invention is not limited thereto. The discharge valve <NUM> may be a switching valve that switches the flow directions by sliding the valve body inside the valve casing, or may be a switching valve that switches the flow directions by adopting another configuration.

An example has been described in which the discharge valve <NUM> is a direction switching valve. However, the present invention is not limited thereto. For example, the discharge valve <NUM> may be configured to serve as an on-off valve provided in the discharge unit <NUM>. In this configuration, instead of a configuration in which the control unit <NUM> causes the direction switching valve serving as the discharge valve <NUM> to switch between the first state and the second state, the control unit <NUM> causes the on-off valve serving as the discharge valve <NUM> to switch between a valve closed state (first state) and a valve open state (second state).

In addition, the discharge valve <NUM> may be configured to serve as a relief valve that is opened when the pressure of the molten resin inside the reservoir cylinder <NUM> reaches a predetermined pressure or higher.

In addition, when the determination unit <NUM> of the control unit <NUM> (<NUM>) determines that the supply stop condition is satisfied (S202: Yes / S302: Yes), in other words, that the cylinder(reservoir cylinder <NUM> and/or injection cylinder <NUM>) of the injection units <NUM> and 3A cannot receive the molten resin, instead of a configuration in which the direction switching valve serving as the discharge valve <NUM> is caused to switch between the first state and the second state, a configuration may be adopted to close the control valve <NUM> (refer to <FIG>) of the molten resin supply path <NUM>. In this manner, the supply of the molten resin to the injection unit <NUM> can be blocked.

In addition, when the determination unit <NUM> of the control unit <NUM> (<NUM>) determines that the supply stop condition is satisfied (S202: Yes / S302: Yes), in other words, that the cylinder (reservoir cylinder <NUM> and/or injection cylinder <NUM>) of the injection units <NUM> and 3A cannot receive the molten resin, a configuration may be adopted in which a signal indicating the determination is transmitted to a host management device (not illustrated) that controls the whole injection molding machine system S. The host management device receiving the signal controls (closes) the control valve <NUM> that controls the whole injection molding machine system S, for example, that controls the molten resin supply device <NUM>. In this manner, the supply of the molten resin to the injection unit <NUM> can be blocked.

An example has been described in which only the molten resin is supplied to the injection units <NUM> and 3A. However, the present invention is not limited thereto. For example, a configuration may be adopted so that the molten resin and pellets are supplied to the first cylinder. In this case, a screw may be provided in the first cylinder instead of the first plunger. In addition, the first plunger drive unit <NUM> may include a screw rotating motor for rotating the screw, and a screw advancing and retreating motor for turning the screw inside the first cylinder.

Claim 1:
An injection molding machine (<NUM>) comprising:
an injection unit (<NUM>, 3A) which includes a reservoir cylinder (<NUM>) and an injection cylinder (<NUM>) and to which a molten resin is supplied;
a supply unit (<NUM>) that supplies the molten resin to the reservoir cylinder (<NUM>) and the injection cylinder (<NUM>) ;
a discharge unit (<NUM>) that discharges the molten resin supplied to the injection unit (<NUM>, 3A);
a nozzle (<NUM>) that injects the molten resin supplied to the injection cylinder (<NUM>) into a mold unit;
a control unit (<NUM>, <NUM>) that controls the injection unit (<NUM>, 3A);
a switching unit (<NUM>) that switches flow directions of the molten resin among a supply/discharge switching unit (<NUM>, 70A), the injection cylinder (<NUM>), and the nozzle (<NUM>); and
the supply/discharge switching unit (<NUM>, 70A) that switches flow directions of the molten resin among the supply unit (<NUM>), the reservoir cylinder (<NUM>), the switching unit (<NUM>), and the discharge unit (<NUM>),
wherein
the control unit (<NUM>, <NUM>) includes
a determination unit (<NUM>) that determines whether or not the molten resin is capable of being received in the injection cylinder (<NUM>), and
a processing unit (<NUM>) that controls the supply/discharge switching unit (<NUM>, 70A) such that the flow direction of the molten resin is switched, based on a determination result of the determination unit (<NUM>).