Patent Description:
An injection molding machine includes a cylinder to which a resin pellet serving as a molding material is supplied, and a heater that heats the cylinder to melt the resin pellet. The injection molding machine manufactures a molding product by melting the resin pellet inside the cylinder and filling a cavity space inside a mold unit with a molten resin.

Then, various proposals have been made for heater control to melt the resin pellet in the injection molding machine. For example, according to a technique disclosed in <CIT>, the technique has proposed the followings. A set temperature of a lower portion of a hopper in a headstock having the hopper installed to supply the resin pellet is automatically set depending on a set temperature of the cylinder heated by a band heater closest to the headstock. <CIT> discloses a screw for an injection molding machine including a plurality of main flights and a plurality of sub-flights and capable of improving melting ability and decreasing a resin temperature of a transported molding material.

<CIT> discloses a technique for automatically setting the set temperature of the lower portion of the hopper, and does not disclose a technique for setting a temperature of the heater in view of a molten state of the molding material. The molding material supplied to the cylinder is heated from the vicinity of a resin feed port. In this manner, it is possible to shorten a plasticizing time until the molding material is accumulated in a completely molten state in a tip portion of the cylinder. On the other hand, when the molding material is excessively heated, the molding material melts near a root of the cylinder, and the molding material adheres to a screw. For this reason, the molding material is not advanced to the tip portion of the cylinder. As a result, the plasticizing time may be extended in some cases.

One aspect of the present invention is to provide a technique for shortening the plasticizing time and improving productivity by performing heating control on the molding material at a proper temperature.

According to one aspect of the present invention, there is provided an injection molding machine including an injection unit and a control device. The injection unit fills a mold unit with a molding material plasticized inside a cylinder. The control device controls the injection unit. The control device includes an initial set temperature setting unit, a plasticizing processing unit, a plasticizing time measurement unit, and a set temperature determining unit. The initial set temperature setting unit sets a plurality of initial set temperatures used to determine a set temperature for the cylinder by raising the initial set temperature from an initial value of the initial set temperature, the initial value of the initial set temperature being determined depending on a usage mode and the molding material or being input by a user. The plasticizing processing unit rotationally drives a screw such that a plasticizing process of the molding material is performed, at each of the different initial set temperatures. The plasticizing time measurement unit measures a plasticizing time during the plasticizing process performed by the plasticizing processing unit for each of the initial set temperatures. The set temperature determining unit determines the set temperature for the cylinder, based on a plurality of the plasticizing times measured for each of the initial set temperatures by the plasticizing time measurement unit.

According to one aspect of the present invention, a plasticizing time is shortened, and productivity is improved by performing heating control on a molding material at a proper temperature.

In each drawing, the same or corresponding reference numerals will be assigned to the same or corresponding configurations, and description thereof will be omitted.

<FIG> is a view illustrating a state when mold opening is completed in an injection molding machine according to a first embodiment. <FIG> is a view illustrating a state when mold clamping is performed in the injection molding machine according to the first embodiment. In the present specification, an X-axial direction, a Y-axial direction, and a Z-axial direction are perpendicular to each other. The X-axial direction and the Y-axial direction represent a horizontal direction, and the Z-axial direction represents a vertical direction. When a mold clamping unit <NUM> is a horizontal type, the X-axial direction represents a mold opening and closing direction, and the Y-axial direction represents a width direction of the injection molding machine <NUM>. A negative side in the Y-axial direction will be referred to as an operation side, and a positive side in the Y-axial direction will be referred to as an anti-operation side.

As illustrated in <FIG> and <FIG>, the injection molding machine <NUM> includes a mold clamping unit <NUM> that opens and closes a mold unit <NUM>, an ejector unit <NUM> that ejects a molding product molded by the mold unit <NUM>, an injection unit <NUM> that injects a molding material into the mold unit <NUM>, a moving unit <NUM> that advances and retreats the injection unit <NUM> with respect to the mold unit <NUM>, a control device <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 frame <NUM> includes a mold clamping unit frame <NUM> that supports the mold clamping unit <NUM>, and an injection unit frame <NUM> that supports the injection unit <NUM>. The mold clamping unit frame <NUM> and the injection unit frame <NUM> are respectively installed on a floor <NUM> via a leveling adjuster <NUM>. The control device <NUM> is disposed in an internal space of the injection unit frame <NUM>. Hereinafter, each component of the injection molding machine <NUM> will be described.

In describing the mold clamping unit <NUM>, a moving direction of a movable platen <NUM> during mold closing (for example, a positive direction of an X-axis) will be defined as forward, and a moving direction of the movable platen <NUM> during mold opening (for example, a negative direction of the X-axis) will be defined as rearward.

The mold clamping unit <NUM> performs mold closing, pressurizing, mold clamping, depressurizing, and mold opening of the mold unit <NUM>. The mold unit <NUM> includes a stationary die <NUM> and a movable die <NUM>.

For example, the mold clamping unit <NUM> is a horizontal type, and the mold opening and closing direction is a horizontal direction. The mold clamping unit <NUM> includes a stationary platen <NUM> to which the stationary die <NUM> is attached, a movable platen <NUM> to which the movable die <NUM> is attached, and a moving mechanism <NUM> that moves the movable platen <NUM> in the mold opening and closing direction with respect to the stationary platen <NUM>.

The stationary platen <NUM> is fixed to the mold clamping unit frame <NUM>. The stationary die <NUM> is attached to a surface facing the movable platen <NUM> in the stationary platen <NUM>.

The movable platen <NUM> is disposed to be movable in the mold opening and closing direction with respect to the mold clamping unit frame <NUM>. A guide <NUM> that guides the movable platen <NUM> is laid on the mold clamping unit frame <NUM>. The movable die <NUM> is attached to a surface facing the stationary platen <NUM> in the movable platen <NUM>.

The movable platen <NUM> is advanced and retreated with respect to the stationary platen <NUM>. In this manner, the moving mechanism <NUM> performs mold closing, pressurizing, mold clamping, depressurizing, and mold opening of the mold unit <NUM>. The moving mechanism <NUM> includes a toggle support <NUM> disposed at an interval from the stationary platen <NUM>, a tie bar <NUM> that connects the stationary platen <NUM> and the toggle support <NUM> to each other, a toggle mechanism <NUM> that moves the movable platen <NUM> in the mold opening and closing direction with respect to the toggle support <NUM>, a mold clamping motor <NUM> that operates the toggle mechanism <NUM>, a motion conversion mechanism <NUM> that converts a rotary motion into a linear motion of the mold clamping motor <NUM>, and a mold space adjustment mechanism <NUM> that adjusts an interval between the stationary platen <NUM> and the toggle support <NUM>.

The toggle support <NUM> is disposed at an interval from the stationary platen <NUM>, and is mounted on the mold clamping unit frame <NUM> to be movable in the mold opening and closing direction. The toggle support <NUM> may be disposed to be movable along a guide laid on the mold clamping unit frame <NUM>. The guide of the toggle support <NUM> may be common to the guide <NUM> of the movable platen <NUM>.

In the present embodiment, the stationary platen <NUM> is fixed to the mold clamping unit frame <NUM>, and the toggle support <NUM> is disposed to be movable in the mold opening and closing direction with respect to the mold clamping unit frame <NUM>. However, the toggle support <NUM> may be fixed to the mold clamping unit frame <NUM>, and the stationary platen <NUM> may be disposed to be movable in the mold opening and closing direction with respect to the mold clamping unit frame <NUM>.

The tie bar <NUM> connects the stationary platen <NUM> and the toggle support <NUM> to each other at an interval L in the mold opening and closing direction. A plurality of (for example, four) tie bars <NUM> may be used. The plurality of tie bars <NUM> are disposed parallel to each other in the mold opening and closing direction, and extend in accordance with a mold clamping force. At least one of the tie bars <NUM> may be provided with a tie bar strain detector <NUM> that detects a strain of the tie bar <NUM>. The tie bar strain detector <NUM> transmits a signal indicating a detection result thereof to the control device <NUM>. The detection result of the tie bar strain detector <NUM> is used in detecting the mold clamping force.

In the present embodiment, as a mold clamping force detector for detecting the mold clamping force, the tie bar strain detector <NUM> is used. However, the present invention is not limited thereto. The mold clamping force detector is not limited to a strain gauge type. The mold clamping force detector may be a piezoelectric type, a capacitive type, a hydraulic type, or an electromagnetic type, and an attachment position thereof is not limited to the tie bar <NUM>.

The toggle mechanism <NUM> is disposed between the movable platen <NUM> and the toggle support <NUM>, and moves the movable platen <NUM> in the mold opening and closing direction with respect to the toggle support <NUM>. The toggle mechanism <NUM> has a crosshead <NUM> that moves in the mold opening and closing direction, and a pair of link groups bent and stretched by a movement of the crosshead <NUM>. Each of the pair of link groups has a first link <NUM> and a second link <NUM> which are connected to be freely bent and stretched by a pin. The first link <NUM> is oscillatingly attached to the movable platen <NUM> by a pin. The second link <NUM> is oscillatingly attached to the toggle support <NUM> by a pin. The second link <NUM> is attached to the crosshead <NUM> via a third link <NUM>. When the crosshead <NUM> is advanced and retreated with respect to the toggle support <NUM>, the first link <NUM> and the second link <NUM> are bent and stretched, and the movable platen <NUM> is advanced and retreated with respect to the toggle support <NUM>.

A configuration of the toggle mechanism <NUM> is not limited to configurations illustrated in <FIG> and <FIG>. For example, in <FIG> and <FIG>, the number of nodes in each link group is five, but may be four. One end portion of the third link <NUM> may be connected to the node between the first link <NUM> and the second link <NUM>.

The mold clamping motor <NUM> is attached to the toggle support <NUM>, and operates the toggle mechanism <NUM>. The mold clamping motor <NUM> advances and retreats the crosshead <NUM> with respect to the toggle support <NUM>. In this manner, the first link <NUM> and second link <NUM> are bent and stretched so that the movable platen <NUM> is advanced and retreated with respect to the toggle support <NUM>. The mold clamping motor <NUM> is directly connected to the motion conversion mechanism <NUM>, but may be connected to the motion conversion mechanism <NUM> via a belt or a pulley.

The motion conversion mechanism <NUM> converts a rotary motion of the mold clamping motor <NUM> into a linear motion of the crosshead <NUM>. The motion conversion mechanism <NUM> includes a screw shaft and a screw nut screwed to the screw shaft. A ball or a roller may be interposed between the screw shaft and the screw nut.

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 device <NUM>.

In the mold closing process, the mold clamping motor <NUM> is driven to advance the movable platen <NUM> by advancing the crosshead <NUM> to a mold closing completion position at a set movement speed. In this manner, the movable die <NUM> is caused to touch the stationary die <NUM>. For example, a position or a movement speed of the crosshead <NUM> is detected by using a mold clamping motor encoder <NUM>. The mold clamping motor encoder <NUM> detects rotation of the mold clamping motor <NUM>, and transmits a signal indicating a detection result thereof to the control device <NUM>.

A crosshead position detector for detecting a position of the crosshead <NUM> and a crosshead movement speed measurer for measuring a movement speed of the crosshead <NUM> are not limited to the mold clamping motor encoder <NUM>, and a general detector can be used. In addition, a movable platen position detector for detecting a position of the movable platen <NUM> and a movable platen movement speed measurer for measuring a movement speed of the movable platen <NUM> are not limited to the mold clamping motor encoder <NUM>, and a general detector can be used.

In the pressurizing process, the mold clamping motor <NUM> is further driven to further advance the crosshead <NUM> from the mold closing completion position to a mold clamping position, thereby generating a mold clamping force.

In the mold clamping process, the mold clamping motor <NUM> is driven to maintain a position of the crosshead <NUM> at the mold clamping position. In the mold clamping process, the mold clamping force generated in the pressurizing process is maintained. In the mold clamping process, a cavity space <NUM> (refer to <FIG>) is formed between the movable die <NUM> and the stationary die <NUM>, and the injection unit <NUM> fills the cavity space <NUM> with a liquid molding material. A molding product is obtained by solidifying the molding material filled therein.

The number of the cavity spaces <NUM> may be one or more. In the latter case, a plurality of the molding products can be obtained at the same time. An insert material may be disposed in a portion of the cavity space <NUM>, and the other portion of the cavity space <NUM> may be filled with the molding material. A molding product in which the insert material and the molding material are integrated with each other can be obtained.

In the depressurizing process, the mold clamping motor <NUM> is driven to retreat the crosshead <NUM> from the mold clamping position to a mold opening start position. In this manner, the movable platen <NUM> is retreated to reduce the mold clamping force. The mold opening start position and the mold closing completion position may be the same position.

In the mold opening process, the mold clamping motor <NUM> is driven to retreat the crosshead <NUM> from the mold opening start position to the mold opening completion position at a set movement speed. In this manner, the movable platen <NUM> is retreated so that the movable die <NUM> is separated from the stationary die <NUM>. Thereafter, the ejector unit <NUM> ejects the molding product from the movable die <NUM>.

Setting conditions in the mold closing process, the pressurizing process, and the mold clamping process are collectively set as a series of setting conditions. For example, the movement speed or positions of the crosshead <NUM> (including the mold closing start position, the movement speed switching position, the mold closing completion position, and the mold clamping position) and the mold clamping force in the mold closing process and the pressurizing process are collectively set as a series of setting conditions. The mold closing start position, the movement speed switching position, the mold closing completion position, and the mold clamping position are aligned in this order from a rear side toward a front side, and represent a start point and an end point of a section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be one or more. The movement speed switching position may not be set. Only one of the mold clamping position and the mold clamping force may be set.

The setting conditions in the depressurizing process and the mold opening process are set in the same manner. For example, the movement speed or positions (the mold opening start position, the movement speed switching position, and the mold opening completion position) of the crosshead <NUM> in the depressurizing process and the mold opening process are collectively set as a series of setting conditions. The mold opening start position, the movement speed switching position, and the mold opening completion position are aligned in this order from the front side toward the rear side, and represent the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be one or more. The movement speed switching position may not be set. The mold opening start position and the mold closing completion position may be the same position. In addition, the mold opening completion position and the mold closing start position may be the same position.

Instead of the movement speed or the position of the crosshead <NUM>, the movement speed or the positions of the movable platen <NUM> may be set. In addition, instead of the position (for example, the mold clamping position) of the crosshead or the position of the movable platen, the mold clamping force may be set.

Incidentally, the toggle mechanism <NUM> amplifies a driving force of the mold clamping motor <NUM>, and transmits the driving force to the movable platen <NUM>. An amplification magnification is referred to as a toggle magnification. The toggle magnification is changed according to an angle θ (hereinafter, also referred to as a "link angle θ") formed between the first link <NUM> and the second link <NUM>. The link angle θ is obtained from the position of the crosshead <NUM>. When the link angle θ is <NUM>°, the toggle magnification is maximized.

When a mold space of the mold unit <NUM> is changed due to replacement of the mold unit <NUM> or a temperature change in the mold unit <NUM>, mold space adjustment is performed so that a predetermined mold clamping force is obtained during the mold clamping. For example, in the mold space adjustment, the interval L between the stationary platen <NUM> and the toggle support <NUM> is adjusted so that the link angle θ of the toggle mechanism <NUM> becomes a predetermined angle when the movable die <NUM> touches the stationary die <NUM>.

The mold clamping unit <NUM> has the mold space adjustment mechanism <NUM>. The mold space adjustment mechanism <NUM> performs the mold space adjustment by adjusting the interval L between the stationary platen <NUM> and the toggle support <NUM>. For example, a timing for the mold space adjustment is determined from an end point of a molding cycle to a start point of a subsequent molding cycle. For example, the mold space adjustment mechanism <NUM>, has a screw shaft <NUM> formed in a rear end portion of the tie bar <NUM>, a screw nut <NUM> held by the toggle support <NUM> to be rotatable and not to be advanced and retreated, and a mold space adjustment motor <NUM> that rotates the screw nut <NUM> screwed to the screw shaft <NUM>.

The screw shaft <NUM> and the screw nut <NUM> are provided for each of the tie bars <NUM>. A rotational driving force of the mold space adjustment motor <NUM> may be transmitted to a plurality of the screw nuts <NUM> via a rotational driving force transmitting unit <NUM>. The plurality of screw nuts <NUM> can be rotated in synchronization with each other. The plurality of screw nuts <NUM> can be individually rotated by changing a transmission channel of the rotational driving force transmitting unit <NUM>.

For example, the rotational driving force transmitting unit <NUM> is configured to include a gear. In this case, a driven gear is formed on an outer periphery of each screw nut <NUM>, a driving gear is attached to an output shaft of the mold space adjustment motor <NUM>, and a plurality of intermediate gears meshing with the driven gear and the driving gear are held to be rotatable in a central portion of the toggle support <NUM>. The rotational driving force transmitting unit <NUM> may be configured to include a belt or a pulley instead of the gear.

An operation of the mold space adjustment mechanism <NUM> is controlled by the control device <NUM>. The control device <NUM> drives the mold space adjustment motor <NUM> to rotate the screw nut <NUM>. As a result, a position of the toggle support <NUM> with respect to the tie bar <NUM> is adjusted, and the interval L between the stationary platen <NUM> and the toggle support <NUM> is adjusted. In addition, a plurality of the mold space adjustment mechanisms may be used in combination.

The interval L is detected by using the mold space adjustment motor encoder <NUM>. The mold space adjustment motor encoder <NUM> detects a rotation amount or a rotation direction of the mold space adjustment motor <NUM>, and transmits a signal indicating a detection result thereof to the control device <NUM>. The detection result of the mold space adjustment motor encoder <NUM> is used in monitoring or controlling the position or the interval L of the toggle support <NUM>. A toggle support position detector for detecting the position of the toggle support <NUM> and an interval detector for detecting the interval L are not limited to the mold space adjustment motor encoder <NUM>, and a general detector can be used.

The mold clamping unit <NUM> may have a mold temperature controller that adjusts the temperature of the mold unit <NUM>. The mold unit <NUM> has a flow path of the temperature control medium inside the mold unit <NUM>. The mold temperature controller adjusts the temperature of the mold unit <NUM> by adjusting the temperature of the temperature control medium supplied to the flow path of the mold unit <NUM>.

The mold clamping unit <NUM> of the present embodiment is the horizontal type in which the mold opening and closing direction is the horizontal direction, but may be a vertical type in which the mold opening and closing direction is an upward-downward direction.

The mold clamping unit <NUM> of the present embodiment has the mold clamping motor <NUM> as a drive source. However, a hydraulic cylinder may be provided instead of the mold clamping motor <NUM>. In addition, the mold clamping unit <NUM> may have a linear motor for mold opening and closing, and may have an electromagnet for mold clamping.

In describing the ejector unit <NUM>, similarly to the description of the mold clamping unit <NUM>, a moving direction of the movable platen <NUM> during the mold closing (for example, the positive direction of the X-axis) will be defined as forward, and a moving direction of the movable platen <NUM> during the mold opening (for example, the negative direction of the X-axis) will be defined as rearward.

The ejector unit <NUM> is attached to the movable platen <NUM>, and is advanced and retreated together with the movable platen <NUM>. The ejector unit <NUM> has an ejector rod <NUM> that ejects a molding product from the mold unit <NUM>, and a drive mechanism <NUM> that moves the ejector rod <NUM> in the moving direction (X-axial direction) of the movable platen <NUM>.

The ejector rod <NUM> is disposed to be freely advanced and retreated in a through-hole of the movable platen <NUM>. A front end portion of the ejector rod <NUM> comes into contact with an ejector plate <NUM> of the movable die <NUM>. The front end portion of the ejector rod <NUM> may be connected to or may not be connected to the ejector plate <NUM>.

For example, the drive mechanism <NUM> has an ejector motor and a motion conversion mechanism that converts a rotary motion of the ejector motor into a linear motion of the ejector rod <NUM>. The motion conversion mechanism includes a screw shaft and a screw nut screwed to the screw shaft. A ball or a roller may be interposed between the screw shaft and the screw nut.

The ejector unit <NUM> performs an ejection process under the control of the control device <NUM>. In the ejection process, the ejector rod <NUM> is advanced from a standby position to an ejection position at a set movement speed. In this manner, the ejector plate <NUM> is advanced to eject the molding product. Thereafter, the ejector motor is driven to retreat the ejector rod <NUM> at a set movement speed, and the ejector plate <NUM> is retreated to an original standby position.

For example, a position or a movement speed of the ejector rod <NUM> is detected by using an ejector motor encoder. The ejector motor encoder detects the rotation of the ejector motor, and transmits a signal indicating a detection result thereof to the control device <NUM>. An ejector rod position detector for detecting the position of the ejector rod <NUM>, and an ejector rod movement speed measurer for measuring the movement speed of the ejector rod <NUM> are not limited to the ejector motor encoder, and a general detector can be used.

In describing the injection unit <NUM>, unlike the description of the mold clamping unit <NUM> or the description of the ejector unit <NUM>, a moving direction of the screw <NUM> during filling (for example, the negative direction of the X-axis) will be defined as forward, and a moving direction of the screw <NUM> during plasticizing (for example, the positive direction of the X-axis) will be defined as rearward.

The injection unit <NUM> is installed in a slide base <NUM>, and the slide base <NUM> is disposed to be freely advanced and retreated with respect to the injection unit frame <NUM>. The injection unit <NUM> is disposed as to be freely advanced and retreated with respect to the mold unit <NUM>. The injection unit <NUM> touches the mold unit <NUM>, and fills the cavity space <NUM> inside the mold unit <NUM> with the molding material plasticized inside a cylinder <NUM>. For example, the injection unit <NUM> has a cylinder <NUM> that heats the molding material, a nozzle <NUM> provided in a front end portion of the cylinder <NUM>, a screw <NUM> disposed to be freely advanced and retreated and rotatable inside the cylinder <NUM>, a plasticizing motor <NUM> that rotates the screw <NUM>, an injection motor <NUM> that advances and retreats the screw <NUM>, and a load detector <NUM> that measures a load transmitted between the injection motor <NUM> and the screw <NUM>.

The cylinder <NUM> heats the molding material supplied into the cylinder <NUM> from a feed port <NUM>. For example, the molding material includes a resin. For example, the molding material is formed in a pellet shape, and is supplied to the feed port <NUM> in a solid state. The feed port <NUM> is formed in a rear portion of the cylinder <NUM>. A cooler <NUM> such as a water-cooling cylinder is provided on an outer periphery of the rear portion of the cylinder <NUM>. In front of the cooler <NUM>, a heating unit <NUM> such as a band heater and a temperature measurer <NUM> are provided on an outer periphery of the cylinder <NUM>.

The cylinder <NUM> is divided into a plurality of zones in the axial direction (for example, the X-axial direction) of the cylinder <NUM>. The heating unit <NUM> and the temperature measurer <NUM> are provided in each of the plurality of zones. The control device <NUM> controls the heating unit <NUM> so that a set temperature is set in each of the plurality of zones and a measurement temperature of the temperature measurer <NUM> reaches the set temperature.

The nozzle <NUM> is provided in a front end portion of the cylinder <NUM>, and is pressed against the mold unit <NUM>. The heating unit <NUM> and the temperature measurer <NUM> are provided on the outer periphery of the nozzle <NUM>. The control device <NUM> controls the heating unit <NUM> so that a measurement temperature of the nozzle <NUM> reaches the set temperature.

The screw <NUM> is disposed to be rotatable and to be freely advanced and retreated inside the cylinder <NUM>. When the screw <NUM> is rotated, the molding material is fed forward along a helical groove of the screw <NUM>. The molding material is gradually melted by heat from the cylinder <NUM> while being fed forward. As the liquid molding material is fed forward of the screw <NUM> and is accumulated in a front portion of the cylinder <NUM>, the screw <NUM> is retreated. Thereafter, when the screw <NUM> is advanced, the liquid molding material accumulated in front of the screw <NUM> is injected from the nozzle <NUM>, and fills the inside of the mold unit <NUM>.

As a backflow prevention valve for preventing a backflow of the molding material fed rearward from the front of the screw <NUM> when the screw <NUM> is pressed forward, a backflow prevention ring <NUM> is attached to the front portion of the screw <NUM> to be freely advanced and retreated.

The backflow prevention ring <NUM> is pressed rearward by the pressure of the molding material in front of the screw <NUM> when the screw <NUM> is advanced, and is relatively retreated with respect to the screw <NUM> to a close position (refer to <FIG>) for closing a flow path of the molding material. In this manner, the backflow of the molding material accumulated in front of the screw <NUM> is prevented.

On the other hand, the backflow prevention ring <NUM> is pressed forward by the pressure of the molding material fed forward along the helical groove of the screw <NUM> when the screw <NUM> is rotated, and is relatively advanced with respect to the screw <NUM> to an open position (refer to <FIG>) for opening the flow path of the molding material. In this manner, the molding material is fed forward of the screw <NUM>.

The backflow prevention ring <NUM> may be either a co-rotation type rotating together with the screw <NUM> or a non-co-rotation type that does not rotate together with the screw <NUM>.

The injection unit <NUM> may have a drive source that advances and retreats the backflow prevention ring <NUM> with respect to the screw <NUM> between the open position and the close position.

The plasticizing motor <NUM> rotates the screw <NUM>. The drive source for rotating the screw <NUM> is not limited to the plasticizing motor <NUM>, and may be a hydraulic pump, for example.

The injection motor <NUM> advances and retreats the screw <NUM>. A motion conversion mechanism that converts a rotary motion of the injection motor <NUM> into a linear motion of the screw <NUM> is provided between the injection motor <NUM> and the screw <NUM>. For example, the motion conversion mechanism has a screw shaft and a screw nut screwed to the screw shaft. A ball or a roller may be provided between the screw shaft and the screw nut. The drive source that advances and retreats the screw <NUM> is not limited to the injection motor <NUM>, and may be a hydraulic cylinder, for example.

The load detector <NUM> measures a load transmitted between the injection motor <NUM> and the screw <NUM>. The detected load is converted into the pressure by the control device <NUM>. The load detector <NUM> is provided in a load transmission channel between the injection motor <NUM> and the screw <NUM>, and measures the load acting on the load detector <NUM>.

The load detector <NUM> transmits a signal of the detected load to the control device <NUM>. The load detected by the load detector <NUM> is converted into the pressure acting between the screw <NUM> and the molding material, and is used in controlling or monitoring the pressure received from the molding material by the screw <NUM>, a back pressure against the screw <NUM>, or the pressure acting on the molding material from the screw <NUM>.

The pressure detector for detecting the pressure of the molding material is not limited to the load detector <NUM>, and a general detector can be used. For example, a nozzle pressure sensor or a mold internal pressure sensor may be used. The nozzle pressure sensor is installed in the nozzle <NUM>. The mold internal pressure sensor is installed inside the mold unit <NUM>.

The injection unit <NUM> performs a plasticizing process, a filling process, and a holding pressure process under the control of the control device <NUM>. The filling process and the holding pressure process may be collectively referred to as an injection process.

In the plasticizing process, the plasticizing motor <NUM> is driven to rotate the screw <NUM> at a set rotation speed, and the molding material is fed forward along the helical groove of the screw <NUM>. As a result, the molding material is gradually melted. As the liquid molding material is fed forward of the screw <NUM> and is accumulated in a front portion of the cylinder <NUM>, the screw <NUM> is retreated. For example, a rotation speed of the screw <NUM> is measured by using a plasticizing motor encoder <NUM>. The plasticizing motor encoder <NUM> detects the rotation of the plasticizing motor <NUM>, and transmits a signal indicating a detection result thereof to the control device <NUM>. A screw rotational speed measurer for measuring the rotation speed of the screw <NUM> is not limited to the plasticizing motor encoder <NUM>, and a general detector can be used.

In the plasticizing process, the injection motor <NUM> may be driven to apply a preset back pressure to the screw <NUM> in order to limit sudden retreat of the screw <NUM>. The back pressure applied to the screw <NUM> is measured by using the load detector <NUM>, for example. When the screw <NUM> is retreated to a plasticizing completion position and a predetermined amount of the molding material is accumulated in front of the screw <NUM>, the plasticizing process is completed.

The position and the rotation speed of the screw <NUM> in the plasticizing process are collectively set as a series of setting conditions. For example, a plasticizing start position, a rotation speed switching position, and a plasticizing completion position are set. The positions are aligned in this order from the front side toward the rear side, and represent the start point and the end point of the section in which the rotation speed is set. The rotation speed is set for each section. The number of the rotation speed switching positions may be one or more. The rotation speed switching position may not be set. In addition, the back pressure is set for each section.

In the filling process, the injection motor <NUM> is driven to advance the screw <NUM> at a set movement speed, and the cavity space <NUM> inside the mold unit <NUM> is filled with the liquid molding material accumulated in front of the screw <NUM>. The position or the movement speed of the screw <NUM> is detected by using an injection motor encoder <NUM>, for example. The injection motor encoder <NUM> detects the rotation of the injection motor <NUM>, and transmits a signal indicating a detection result thereof to the control device <NUM>. When the position of the screw <NUM> reaches a set position, the filling process is switched to the holding pressure process (so-called V/P switching). The position where the V/P switching is performed will be referred to as a V/P switching position. The set movement speed of the screw <NUM> may be changed in accordance with the position or a time of the screw <NUM>.

The position and the movement speed of the screw <NUM> in the filling process are collectively set as a series of setting conditions. For example, a filling start position (also referred to as an "injection start position"), the movement speed switching position, and the V/P switching position are set. The positions are aligned in this order from the rear side toward the front side, and represent the start point and the end point of the section in which the movement speed is set. The movement speed is set for each section. The number of the movement speed switching positions may be one or more. The movement speed switching position may not be set.

An upper limit value of the pressure of the screw <NUM> is set for each section in which the movement speed of the screw <NUM> is set. The pressure of the screw <NUM> is measured by the load detector <NUM>. When the pressure of the screw <NUM> is equal to or lower than a setting pressure, the screw <NUM> is advanced at a set movement speed. On the other hand, when the pressure of the screw <NUM> exceeds the setting pressure, in order to protect the mold, the screw <NUM> is advanced at the movement speed lower than the set movement speed so that the pressure of the screw <NUM> is equal to or lower than the setting pressure.

After the position of the screw <NUM> reaches the V/P switching position in the filling process, the screw <NUM> may be temporarily stopped at the V/P switching position, and thereafter, the V/P switching may be performed. Immediately before the V/P switching, instead of stopping the screw <NUM>, the screw <NUM> may be advanced at a low speed, or may be retreated at a low speed. In addition, a screw position detector for detecting the position of the screw <NUM> and a screw movement speed measurer for measuring the movement speed of the screw <NUM> are not limited to the injection motor encoder <NUM>, and a general detector can be used.

In the holding pressure process, the injection motor <NUM> is driven to press the screw <NUM> forward. A pressure (hereinafter, also referred to as a "holding pressure") of the molding material in the front end portion of the screw <NUM> is held at a setting pressure, and the molding material remaining inside the cylinder <NUM> is pressed toward the mold unit <NUM>. The molding material which is insufficient due to cooling shrinkage inside the mold unit <NUM> can be replenished. The holding pressure is measured by using the load detector <NUM>, for example. A setting value of the holding pressure may be changed depending on an elapsed time from the start of the holding pressure process. The holding pressure and a holding time for holding the holding pressure in the holding pressure process may be respectively set, or may be collectively set as a series of setting conditions.

In the holding pressure process, the molding material in the cavity space <NUM> inside the mold unit <NUM> is gradually cooled, and when the holding pressure process is completed, an inlet of the cavity space <NUM> is closed by the solidified molding material. This state is referred to as gate seal, and prevents the backflow of the molding material from the cavity space <NUM>. After the holding pressure process, a cooling process starts. In the cooling process, the molding material inside the cavity space <NUM> is solidified. In order to shorten a molding cycle time, the plasticizing process may be performed during the cooling process.

The injection unit <NUM> of the present embodiment is an in-line screw type, but may be a pre-plastic type. The injection unit of the pre-plastic type supplies the molding material melted inside a plasticizing cylinder to an injection cylinder, and the molding material is injected into the mold unit from the injection cylinder. Inside the plasticizing cylinder, the screw is disposed to be rotatable and not to be advanced and retreated, or the screw is disposed to be rotatable and to be freely advanced and retreated. On the other hand, a plunger is disposed to be freely advanced and retreated inside the injection cylinder.

In addition, the injection unit <NUM> of the present embodiment is a horizontal type in which the axial direction of the cylinder <NUM> is a horizontal direction, but may be a vertical type in which the axial direction of the cylinder <NUM> is an upward-downward direction. The mold clamping unit combined with the injection unit <NUM> of the vertical type may be the vertical type or the horizontal type. Similarly, the mold clamping unit combined with the injection unit <NUM> of the horizontal type may be the horizontal type or the vertical type.

In describing the moving unit <NUM>, similarly to the description of the injection unit <NUM>, a moving direction of the screw <NUM> during the filling (for example, the negative direction of the X-axis) will be defined as forward, and a moving direction of the screw <NUM> during the plasticizing (for example, the positive direction of the X-axis) will be defined as rearward.

The moving unit <NUM> advances and retreats the injection unit <NUM> with respect to the mold unit <NUM>. The moving unit <NUM> presses the nozzle <NUM> against the mold unit <NUM>, thereby generating a nozzle touch pressure. The moving unit <NUM> includes a hydraulic pump <NUM>, a motor <NUM> serving as a drive source, and a hydraulic cylinder <NUM> serving as a hydraulic actuator.

The hydraulic pump <NUM> has a first port <NUM> and a second port <NUM>. The hydraulic pump <NUM> is a pump that can rotate in both directions, and switches rotation directions of the motor <NUM>. In this manner, a hydraulic fluid (for example, oil) is sucked from any one of the first port <NUM> and the second port <NUM>, and is discharged from the other to generate a hydraulic pressure. The hydraulic pump <NUM> can suck the hydraulic fluid from a tank, and can discharge the hydraulic fluid from any one of the first port <NUM> and the second port <NUM>.

The motor <NUM> operates the hydraulic pump <NUM>. The motor <NUM> drives the hydraulic pump <NUM> in a rotation direction and with a rotation torque in accordance with a control signal transmitted from the control device <NUM>. The motor <NUM> may be an electric motor, or may be an electric servo motor.

The hydraulic cylinder <NUM> has a cylinder body <NUM>, a piston <NUM>, and a piston rod <NUM>. The cylinder body <NUM> is fixed to the injection unit <NUM>. The piston <NUM> partitions the inside of the cylinder body <NUM> into a front chamber <NUM> serving as a first chamber and a rear chamber <NUM> serving as a second chamber. The piston rod <NUM> is fixed to the stationary platen <NUM>.

The front chamber <NUM> of the hydraulic cylinder <NUM> is connected to the first port <NUM> of the hydraulic pump <NUM> via a first flow path <NUM>. The hydraulic fluid discharged from the first port <NUM> is supplied to the front chamber <NUM> via the first flow path <NUM>. In this manner, the injection unit <NUM> is pressed forward. The injection unit <NUM> is advanced, and the nozzle <NUM> is pressed against the stationary die <NUM>. The front chamber <NUM> functions as a pressure chamber that generates the nozzle touch pressure of the nozzle <NUM> by the pressure of the hydraulic fluid supplied from the hydraulic pump <NUM>.

On the other hand, the rear chamber <NUM> of the hydraulic cylinder <NUM> is connected to the second port <NUM> of the hydraulic pump <NUM> via a second flow path <NUM>. The hydraulic fluid discharged from the second port <NUM> is supplied to the rear chamber <NUM> of the hydraulic cylinder <NUM> via the second flow path <NUM>. In this manner, the injection unit <NUM> is pressed rearward. The injection unit <NUM> is retreated, and the nozzle <NUM> is separated from the stationary die <NUM>.

In the present embodiment, the moving unit <NUM> includes the hydraulic cylinder <NUM>, but the present invention is not limited thereto. For example, instead of the hydraulic cylinder <NUM>, an electric motor and a motion conversion mechanism that converts a rotary motion of the electric motor into a linear motion of the injection unit <NUM> may be used.

For example, the control device <NUM> is configured to include a computer, and has a central processing unit (CPU) <NUM>, a storage medium <NUM> such as a memory, an input interface <NUM>, and an output interface <NUM> as illustrated in <FIG> and <FIG>. The control device <NUM> performs various types of control by causing the CPU <NUM> to execute a program stored in the storage medium <NUM>. In addition, the control device <NUM> receives a signal from the outside through the input interface <NUM>, and transmits the signal to the outside through the output interface <NUM>.

The control device <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. The completion of the depressurizing process coincides with the 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 for opening and closing the flow path of the nozzle <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 closes the flow path of the nozzle <NUM>, the molding material does not leak from the nozzle <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.

For example, after the holding pressure process is completed and before the plasticizing process starts, a pre-plasticizing suck-back process of retreating the screw <NUM> to a preset plasticizing start position may be performed. The pressure of the molding material accumulated in front of the screw <NUM> before the plasticizing process starts can be reduced, and it is possible to prevent the screw <NUM> from being rapidly retreated when the plasticizing process starts.

In addition, after the plasticizing process is completed and before the filling process starts, a post-plasticizing suck-back process may be performed in which the screw <NUM> is retreated to a preset filling start position (also referred to as an "injection start position"). The pressure of the molding material accumulated in front of the screw <NUM> before the filling process starts can be reduced, and can prevent a leakage of the molding material from the nozzle <NUM> before the filling process starts.

The control device <NUM> is connected to an operation unit <NUM> that receives an input operation of a user, and a display unit <NUM> that displays a screen. For example, the operation unit <NUM> and the display unit <NUM> may be configured to include a touch panel <NUM>, and may be integrated with each other. The touch panel <NUM> serving as the display unit <NUM> displays the screen under the control of the control device <NUM>. For example, the screen of the touch panel <NUM> may display settings of the injection molding machine <NUM>, and information on a current state of the injection molding machine <NUM>. In addition, for example, the screen of the touch panel <NUM> may display a button for receiving the input operation of the user or an operation unit such as an input column. The touch panel <NUM> serving as the operation unit <NUM> detects an input operation of the user on the screen, and outputs a signal corresponding to the input operation to the control device <NUM>. In this manner, for example, while confirming information displayed on the screen, the user can perform settings (including an input of a setting value) of the injection molding machine <NUM> by operating the operation unit provided on the screen. In addition, the user can operate the injection molding machine <NUM> corresponding to the operation unit by operating the operation unit provided on the screen. For example, the operation of the injection molding machine <NUM> may be the operation (including stopping) of the mold clamping unit <NUM>, the ejector unit <NUM>, the injection unit <NUM>, and the moving unit <NUM>. In addition, the operation of the injection molding machine <NUM> may be switching between the screens displayed on the touch panel <NUM> serving as the display unit <NUM>.

A case has been described in which the operation unit <NUM> and the display unit <NUM> of the present embodiment are integrated with each other as the touch panel <NUM>. However, both of these may be independently provided. In addition, a plurality of the operation units <NUM> may be provided. The operation unit <NUM> and the display unit <NUM> are disposed on the operation side (negative direction of the Y-axis) of the mold clamping unit <NUM> (more specifically, the stationary platen <NUM>).

<FIG> is a view illustrating a main part of the injection unit <NUM> according to a first embodiment. As illustrated in <FIG>, the injection unit <NUM> according to the first embodiment includes the cylinder <NUM> and the screw <NUM> that feeds a resin into the cylinder <NUM>. In addition, as the heating unit <NUM>, the injection unit <NUM> according to the present embodiment includes five heating units 313_1 to 313_5 divided into each zone on the outer periphery of the cylinder <NUM>.

The screw <NUM> integrally includes a screw rotary shaft <NUM> and a flight <NUM> spirally provided around the screw rotary shaft <NUM>. When the screw <NUM> rotates, the flight <NUM> of the screw <NUM> moves, and the resin pellet filling a screw groove of the screw <NUM> is fed forward.

For example, the screw <NUM> is distinguished as a supply zone 330a, a compression zone 330b, and a metering zone 330c from a rear side (hopper <NUM> side) to a front side (nozzle <NUM> side) along the axial direction. The supply zone 330a is a portion that receives the resin pellet and transports the resin pellet forward. The compression zone 330b is a portion that melts the supplied resin while compressing the supplied resin. The metering zone 330c is a portion that plasticizes a fixed amount of the molten resin at a time. A depth of a screw groove of the screw <NUM> is deep in the supply zone 330a, is shallow in the metering zone 330c, and is shallower in the compression zone 330b toward the front side. A configuration of the screw <NUM> is not particularly limited. For example, the depth of the screw groove of the screw <NUM> may be constant. In the present embodiment, a case will be described where ratios of lengths of the supply zone 330a, the compression zone 330b, and the metering zone 330c are approximately <NUM>%, approximately <NUM>%, and approximately <NUM>%. However, the ratios of the lengths are examples. The ratios vary depending on a type of molding material or a usage mode.

The injection molding machine <NUM> injects the molten resin inside the cylinder <NUM> from the nozzle <NUM>, and fills the cavity space <NUM> inside the mold unit <NUM> with the molten resin. The mold unit <NUM> is configured to include the stationary die and the movable die, and the cavity space <NUM> is formed between the stationary die and the movable die when the mold clamping is performed. The resin cooled and solidified in the cavity space <NUM> is unloaded as a molding product after the mold opening is performed. The resin pellet serving as the molding material is supplied from the hopper <NUM> to a rear portion of the cylinder <NUM>.

A resin feed port <NUM> is formed at a predetermined position of the cylinder <NUM>, and the hopper <NUM> is connected to a resin feed port. The resin pellet inside the hopper <NUM> is supplied into the cylinder <NUM> through the resin feed port.

The cylinder <NUM> is divided into six zones along a longitudinal direction leading to the nozzle <NUM>. In the present embodiment, in the six zones, the heating units <NUM> (heaters) are provided in five zones (zones Z1 to Z5), and the cooler <NUM> is provided in one zone (zone Z0). In addition, temperature measurers 314_0 to 314_5 are provided in the respective zones.

In the present embodiment, the five zones will be referred to as a first zone Z1, a second zone Z2, a third zone Z3, a fourth zone Z4, and a fifth zone Z5 in order from the vicinity of the resin feed port. The <NUM>-th zone Z0 is provided in the resin feed port to which the hopper <NUM> is connected. The first zone Z1 and the second zone Z2 are provided in the supply zone 330a that receives the resin pellet and transports the resin pellet forward. The third zone Z3 is provided in the compression zone 330b that melts the supplied resin while compressing the supplied resin. The fourth zone Z4 is provided in the metering zone 330c that plasticizes a fixed amount of the molten resin at a time. The fifth zone Z5 is provided in the vicinity of the nozzle <NUM>. In addition, in the present embodiment, an example is described in which temperature control is performed on each of the <NUM>-th zone Z0 to the fifth zone Z5. The example is not limited to a method of performing the temperature control in zone units described in the present embodiment. A section for performing the temperature control is determined depending on a usage mode such as the length of the cylinder <NUM> and the molding material.

In the <NUM>-th zone Z0, the cooler <NUM> is disposed on the outer periphery of the cylinder <NUM>.

The cooler <NUM> is provided behind the plurality of heating units 313_1 to 313_5 (in the vicinity of the resin feed port). The temperature of the <NUM>-th zone Z0 provided with the cooler <NUM> is raised by heat transmitted from the first zone Z1. Therefore, the cooler <NUM> cools the rear portion of the cylinder <NUM> under the control of the control device <NUM>, and holds the temperature of the rear portion of the cylinder <NUM> at a temperature which does not cause the surface of the resin pellet to melt so that bridging (lumping) of the resin pellet does not occur in the rear portion of the cylinder <NUM> or inside the hopper <NUM>. The cooler <NUM> has a flow path <NUM> for a refrigerant such as water or air. Then, the control device <NUM> adjusts the temperature by adjusting a flow rate of the refrigerant flowing through the flow path <NUM>. The temperature of the zone Z0 is measured by the temperature measurers 314_0.

The heating units 313_1 to 313_5 which are individually energized are respectively disposed on the outer periphery of the cylinder <NUM> in the first zone Z1, the second zone Z2, the third zone Z3, the fourth zone Z4, and the fifth zone Z5. For example, as the heating units 313_1 to 313_5, a band heater that heats the cylinder <NUM> from the outside is used. The band heater is provided to surround the outer periphery of the cylinder <NUM>. In other words, the heating units 313_1 to 313_5 having planar shapes corresponding to the first zone Z1 to the fifth zone Z5 are attached to the outer periphery of the cylinder <NUM>. Since the heating units 313_1 to 313_5 are energized, the resin pellet can be heated and melted inside the cylinder <NUM>.

The plurality of heating units 313_1 to 313_5 are arrayed along the longitudinal direction of the cylinder <NUM>, and individually heat each of the first zone Z1 to the fifth zone Z5 in which the cylinder <NUM> is divided in the longitudinal direction. The plurality of heating units 313_1 to 313_5 are feedback-controlled by the control device <NUM> so that the temperature of each of the zones Z1 to Z5 becomes a set temperature. The temperatures of the respective zones Z1 to Z5 are measured by the temperature measurers 314_1 to 314_5. An operation of the injection molding machine <NUM> is controlled by the control device <NUM>.

<FIG> is a functional block view illustrating components of the control device <NUM> according to the embodiment. Each functional block illustrated in <FIG> is conceptual, and may not necessarily be configured to be physical as illustrated. All or a portion of each functional block can be configured to be functionally or physically distributed and integrated in any desired unit. Each processing function performed in each functional block is realized by a program in which all or any desired partial functions are performed by the CPU <NUM>. Alternatively, each functional block may be realized as hardware using a wired logic. As illustrated in <FIG>, the control device <NUM> includes an acquisition unit <NUM>, a plasticizing processing unit <NUM>, a plasticizing time measurement unit <NUM>, a filling processing unit <NUM>, an initial set temperature setting unit <NUM>, and a set temperature determining unit <NUM>, and a temperature control processing unit <NUM>. For example, the acquisition unit <NUM> acquires information indicating the temperature measured by the temperature measurers 314_0 to S4, and setting values set in advance. The initial set temperature setting unit <NUM> sets an initial set temperature used to determine a set temperature for the cylinder <NUM>. For example, the plasticizing processing unit <NUM> controls a plasticizing process of plasticizing the molding material for filling the cavity space <NUM> in the cylinder <NUM> at each different initial set temperature. The plasticizing time measurement unit <NUM> measures a plasticizing time while the plasticizing process is performed by the plasticizing processing unit <NUM>. The filling processing unit <NUM> controls a filling process. Based on a plurality of the plasticizing times measured for each initial set temperature, the set temperature determining unit <NUM> determines the set temperature for controlling the heating units 313_1 to 313_5 and the cooler <NUM> in each zone of the cylinder <NUM> for filling the cavity space <NUM> with the molding material. The temperature control processing unit <NUM> controls the heating units 313_1 to 313_5 and the cooler <NUM> in accordance with the temperature set by the initial set temperature setting unit <NUM>. Specific description of each configuration will be described later.

Next, an operation of the injection molding machine <NUM> will be described.

In the plasticizing process, the plasticizing processing unit <NUM> rotationally drives the plasticizing motor <NUM> to rotate the screw <NUM>. In this case, a flight (thread) of the screw <NUM> moves, and the resin pellet (solid molding material) filling the inside of the screw groove of the screw <NUM> is fed forward. While the resin pellet moves forward inside the cylinder <NUM>, the resin pellet is gradually melted by being heated with heat from the heating units 313_1 to 313_5 via the cylinder <NUM>. Then, the resin pellet is brought into a completely molten state in the tip portion of the cylinder <NUM>. Then, as the liquid molding material (resin) is fed forward of the screw <NUM> and is accumulated in a front portion of the cylinder <NUM>, the screw <NUM> is retreated.

The plasticizing motor encoder <NUM> detects the rotation of the plasticizing motor <NUM>, and transmits a signal indicating a detection result thereof to the control device <NUM>. A screw rotational speed measurer for measuring a rotation speed of the screw <NUM> is not limited to the plasticizing motor encoder <NUM>, and a general detector can be used.

The acquisition unit <NUM> acquires a setting value set as the rotation speed of the screw <NUM>.

When the screw <NUM> is retreated by a predetermined distance and a predetermined amount of the liquid molding material (resin) is accumulated in front of the screw <NUM>, the plasticizing processing unit <NUM> stops the rotation of the plasticizing motor <NUM>, and stops the rotation of the screw <NUM>.

In the plasticizing process, the injection motor <NUM> may be driven to apply a preset back pressure to the screw <NUM> in order to limit sudden retreat of the screw <NUM>. The back pressure applied to the screw <NUM> is measured by using the load detector <NUM>, for example. The load detector <NUM> transmits a signal indicating a detection result thereof to the control device <NUM>.

The acquisition unit <NUM> acquires a position of the screw <NUM>, based on a load detection result from the load detector <NUM>.

In the plasticizing processing unit <NUM>, when the screw <NUM> is retreated to a plasticizing completion position and a predetermined amount of the molding material is accumulated in front of the screw <NUM>, the plasticizing process is completed.

The position and the rotation speed of the screw <NUM> in the plasticizing process are collectively set as a series of setting conditions. For example, a plasticizing start position, a rotation speed switching position, and a plasticizing completion position are set. The positions are aligned in this order from the front side toward the rear side, and represent the start point and the end point of the section in which the rotation speed is set. The rotation speed is set for each section. The number of the rotation speed switching positions may be one or more. The rotation speed switching position may not be set. In addition, the back pressure may be set for each section.

The plasticizing time measurement unit <NUM> measures a plasticizing time while the plasticizing process is performed by the plasticizing processing unit <NUM>.

Next, a reason for measuring the plasticizing time will be described. When the temperature of the cylinder <NUM> is raised, a time required until the molding material melts can be shortened. Therefore, plasticizing capacity can be improved, and a molten state can be improved.

In particular, the temperature raised in the zones Z0 to Z2 having the section where the solid molding material (resin pellet) exists such as the supply zone 330a. In this manner, melting of the solid molding material is quickened in the section subsequent to the zone Z3 (for example, the section including the compression zone 330b and the metering zone 330c). In this manner, the plasticizing capacity can be improved. In other words, the amount of the molding material fed to the nozzle <NUM> side can be increased when the screw <NUM> rotates.

On the other hand, when the solid molding material melts in the zones Z0 to Z2 including the supply zone 330a from the resin feed port, the plasticizing time may be extended in some cases. The reason is as follows. The softened molding material adheres to the screw <NUM>, thereby degrading efficiency in feeding the molding material to the nozzle <NUM> side.

In other words, as the set temperature for the heating units 313_1 to 313_2 and the cooler <NUM> is improved, the melting is quickened. Accordingly, the plasticizing time can be shortened. However, when the temperature is set to a predetermined or higher temperature, the plasticizing time is extended.

Therefore, in the injection molding machine <NUM> according to the present embodiment, a plurality of the initial set temperatures used to determine the set temperature for the cylinder <NUM> are set, and the plasticizing process is performed at each of the plurality of initial set temperatures. Then, the set temperature determining unit <NUM> determines a proper set temperature for the heating units 313_1 to 313_2 and the cooler <NUM>, based on the plurality of plasticizing times measured at each of the initial set temperatures measured by the plasticizing time measurement unit <NUM>.

The present embodiment adopts an example of determining the set temperature of the first zone Z1 corresponding to the supply zone 330a which is the section for supplying the molding material by using the screw <NUM> when the plasticizing process starts, from a loading port of the resin pellet serving as the molding material. In the present embodiment, an example of determining the set temperature of the first zone Z1 will be described. However, the set temperature can be determined for other zones (for example, the <NUM>-th zone Z0 and the second zone Z2) by using the same method, and thus, description thereof will be omitted.

The initial set temperature setting unit <NUM> sets an initial set temperature used to determine the set temperature for the cylinder <NUM>. The initial set temperature is set each time the plasticizing time is measured. For example, the initial set temperature setting unit <NUM> sets the subsequent initial set temperature of the heating unit 313_1 corresponding to the first zone, based on the plasticizing time measured by the plasticizing time measurement unit <NUM>. In the present embodiment, the initial set temperature is set, based on whether or not the current plasticizing time is longer than the previous plasticizing time.

In the present embodiment, a temporary temperature until the initial set temperature setting unit <NUM> determines an optimum set temperature for molding out of the temperatures set for the cooler <NUM> and the heating units 313_1 to 313_5 will be referred to as the initial set temperature.

The set temperature determining unit <NUM> compares the initial set temperatures set for the cooler <NUM> and the heating units 313_1 to 313_5, and determines the initial set temperature (in other words, the optimum temperature for molding) having a shortest plasticizing time, as the set temperature.

The initial set temperature setting unit <NUM> of the present embodiment increases the initial setting from the initial value in order to determine the most proper set temperature for molding, and the plasticizing time measurement unit <NUM> measures the plasticizing time for each initial set temperature. Then, when the initial set temperature having the shortest plasticizing time can be specified, the set temperature determining unit <NUM> determines the initial set temperature having the shortest plasticizing time, as the set temperature. Thereafter, the temperature control processing unit <NUM> controls the heating unit 313_1 (in the first zone Z1) so that the temperature reaches the set temperature, and molds the molding product.

<FIG> is a view illustrating a correspondence between the plasticizing time and the initial set temperature. As illustrated in <FIG>, first, as the initial set temperature setting unit <NUM> increases the initial set temperature, the plasticizing time measured by the plasticizing time measurement unit <NUM> is shortened. However, when the initial set temperature is higher than a temperature T0, the plasticizing time starts to increase. The reason is considered as follows. Since the molten molding material starts to adhere to the screw <NUM> or the like due to an increase in the initial set temperature, the molding material does not move forward. Therefore, in the example illustrated in <FIG>, the set temperature determining unit <NUM> determines the temperature T0 before the plasticizing time starts to increase, as the set temperature.

The initial set temperature setting unit <NUM> and the set temperature determining unit <NUM> determine the set temperature for the <NUM>-th zone Z0 and the second zone Z2 to the fifth zone Z5. The set temperatures of the <NUM>-th zone Z0 and the second zone Z2 are determined by using the same method as that of the first zone Z1. In addition, the third zone Z3 to the fifth zone Z5 may be determined by using the same method as that of the first zone Z1, or may be determined by another method.

The temperature control processing unit <NUM> controls the cooler <NUM> disposed in the <NUM>-th zone Z0, and adjusts the temperature to reach the set temperature of the <NUM>-th zone Z0. The cooler <NUM> of the present embodiment can be controlled to be turned on and off within range of a unit time for cooling. The temperature control processing unit <NUM> can adjust the temperature of the <NUM>-th zone Z0 to reach the set temperature, based on the temperature measured by the temperature measurer 314_0 and the control of the cooler <NUM>.

The temperature control processing unit <NUM> controls the heating units 313_1 to 313_5 disposed in the first zone Z1 to the fifth zone Z5, and adjusts the temperature to reach the set temperature set in each of the first zone Z1 to the fifth zone Z5. The heating units 313_1 to 313_5 of the present embodiment can be controlled to be turned on and off within a range of a unit time for heating. For example, when the output is <NUM>%, the temperature control processing unit <NUM> controls the heating units 313_1 to 313_5 to be turned on during a time of "the unit time for heating / <NUM>" and to be turned off during a time of "the unit time for heating / <NUM>". In addition, when the output is maximum, the temperature control processing unit <NUM> controls the heating units 313_1 to 313_5 to be continuously turned on. The temperature control processing unit <NUM> can adjust each temperature of the first zone Z1 to the fifth zone Z5 to reach the set temperature, based on the temperature measured by the temperature measurers 314_1 to 314_5 and the control of the heating units 313_1 to 313_5.

The temperature control processing unit <NUM> of the present embodiment performs feedback control of the cooler <NUM> and the heating units 313_1 to 313_5, based on a deviation between measurement temperatures of the temperature measurers 314_0 to 314_5 and the initial set temperature or the set temperature. In this manner, accuracy in reaching the initial set temperature or the set temperature can be improved. The feedback control may be performed by using the same method as the method in the related art such as PID control, and thus, description thereof will be omitted.

In the filling process, the filling processing unit <NUM> rotationally drives the injection motor <NUM> to advance the screw <NUM>, and perform control to fill the cavity space <NUM> inside the mold unit <NUM> in a mold clamping state with the molten resin (molding material in a molten state). The molding material in the molten state shrinks in the cavity space <NUM> due to cooling. Therefore, in order to replenish the molding material corresponding to the amount of heat shrinkage, a resin pressure (injection pressure of the molding material) applied to the screw <NUM> is held at a predetermined pressure in the holding pressure process.

<FIG> is a flowchart illustrating a process until the set temperature is determined in the first zone Z1 in the injection molding machine <NUM> according to the present embodiment. In an example illustrated in <FIG>, an example of determining the set temperature of the first zone Z1 will be described. However, the same control is performed on other zones (for example, the <NUM>-th zone Z0 and the second zone Z2). When the temperature is adjusted in the <NUM>-th zone Z0, the cooler <NUM> is used. In the present embodiment, only the initial set temperature is changed, and the processes are performed after other conditions (for example, conditions such as the number of rotation times of the screw <NUM> and the position of the cylinder <NUM>) are fixed.

First, the initial set temperature setting unit <NUM> sets an initial value of the initial set temperature of the first zone Z1 (S401). The initial value may be determined depending on a usage mode and a molding material, or may be input by a user.

The plasticizing processing unit <NUM> rotationally drives the plasticizing motor <NUM> to rotate the screw <NUM>, thereby performing the plasticizing process (S402).

The plasticizing time measurement unit <NUM> measures a plasticizing time required for the plasticizing process in a case of the initial set temperature which is currently set (S403).

The initial set temperature setting unit <NUM> raises the initial set temperature of the first zone Z1, and sets the initial set temperature which is higher than the previous initial set temperature (S404).

The plasticizing processing unit <NUM> rotationally drives the plasticizing motor <NUM> to rotate the screw <NUM>, thereby performing the plasticizing process (S405).

The plasticizing time measurement unit <NUM> measures the plasticizing time required for the plasticizing process in a case of the initial set temperature which is currently set (S406).

The initial set temperature setting unit <NUM> determines whether or not the plasticizing time measured this time is longer than the previously measured plasticizing time (S407). When the initial set temperature setting unit <NUM> determines that the plasticizing time measured this time is not longer than the previously measured plasticizing time (in other words, the plasticizing time is shortened) (S407: No), the initial set temperature setting unit <NUM> determines whether or not an output of the heating unit 313_1 of the first zone Z1 which is obtained by the temperature control processing unit <NUM> in the plasticizing process is the maximum (S408). When the initial set temperature setting unit <NUM> determines that the output of the heating unit 313_1 of the first zone Z1 is the maximum (S408: Yes), the process proceeds to the process in S410.

On the other hand, when the initial set temperature setting unit <NUM> determines that the output of the heating unit 313_1 in the first zone Z1 is not the maximum (S408: No), the initial set temperature is raised to set the higher initial set temperature than the previous initial set temperature (S409), and the process is performed again from S402. The temperature to be raised may have a preset number of degrees, and is determined depending on a usage mode. In the present embodiment, the plasticizing process in S402 is performed after stabilizing the temperature measured from the first zone Z1 at the set initial set temperature. In the present embodiment, an example will be described in which the plasticizing process is performed after stabilizing the temperature measured from the first zone Z1 at the set initial set temperature. However, the example is not limited to the method, and the plasticizing process may be performed while raising the output of the heating unit 313_1.

On the other hand, when the initial set temperature setting unit <NUM> determines that the plasticizing time measured this time is longer than the previous plasticizing time (S407: Yes), or when the initial set temperature setting unit <NUM> determines that the output of the heating unit 313_1 of the first zone Z1 is the maximum (S408: Yes), the set temperature determining unit <NUM> determines the initial set temperature corresponding to the shortest plasticizing time of the measured plasticizing times, as the set temperature (S410).

The injection molding machine <NUM> according to the present embodiment includes the above-described configuration. Accordingly, it is possible to control the heating units 313_1 to 313_2 and the cooler <NUM> at a proper set temperature in the plasticizing process. In this manner, the plasticizing capacity can be improved. Specifically, in the vicinity of a root of the cylinder <NUM> from a resin feed port into which the resin pellet (solid molding material) is loaded (for example, a section including the supply zone 330a such as the <NUM>-th zone Z0 to the second zone Z2), the heating units 313_1 to 313_2 and the cooler <NUM> are controlled in accordance with the set temperature set in the above-described process. In this manner, it is possible to achieve both advantageous effects as follows. the plasticizing time required until the resin pellet is brought into a molten state is shortened, and extension of the plasticizing time is suppressed since melting of the resin pellet is suppressed in the vicinity of the root. In this manner, a cycle can be shortened, and productivity can be improved.

Furthermore, since the injection molding machine <NUM> includes the above-described configuration, it is possible to control the heating units 313_1 to 313_2 and the cooler <NUM> at a proper set temperature in the plasticizing process. Therefore, a molten state can be improved. Since the molten state is improved, it is possible to improve a molding product defect caused by a poor molten state, for example, such as a crack caused by mixing of the resin which is not melted. A back pressure can be lowered by improving the molten state. Therefore, it is possible to reduce shear heat generation inside the cylinder <NUM> or to suppress resin deterioration. Furthermore, since the back pressure is lowered, a pressure applied to the molding material is lowered when the molding material is clogged inside the cylinder <NUM>. Therefore, galling can be reduced, and it is possible to suppress a possibility that a life of the screw <NUM> may be shortened.

Furthermore, in the <NUM>-th zone Z0 to the second zone Z2, the molding material (resin pellet) is easily melted by controlling the heating units 313_1 to 313_2 and the cooler <NUM> at the proper set temperature in the plasticizing process. Therefore, it is not necessary to raise the set temperature more than necessary in the third zone Z3 to the fifth zone Z5. In other words, the set temperature can be lowered in a section other than the vicinity of the root of the third zone Z3 to the fifth zone Z5. In this manner, the temperature of the molding material (resin) ejected from the nozzle <NUM> can be lowered. Therefore, a cooling time can be shortened. Therefore, a shortened cycle can be achieved.

Furthermore, the set temperature for each zone of the cylinder <NUM> can be automatically set. Therefore, a user's burden can be reduced.

In the first embodiment, an example has been described in which the initial set temperature corresponding to the shortest plasticizing time is determined as the set temperature. However, the above-described embodiment is not limited to the example in which the initial set temperature corresponding to the shortest plasticizing time is determined as the set temperature. In other words, in some situations, the plasticizing time may be delayed depending on a usage mode. For example, the cooling time may be relatively long in some cases. Therefore, in the modification example, an example will be described in which the set temperature determining unit <NUM> determines the set temperature, based on the plurality of plasticizing times measured in a measurement process and the cooling time.

Incidentally, the plasticizing process is performed during the cooling process of the previous shot. That is, the plasticizing process of the subsequent shot is performed during the cooling process of the current shot. Therefore, the plasticizing time may not exceed the cooling time.

Therefore, in the control device <NUM> in the present modification example, the plasticizing processing unit <NUM> measures the plasticizing time for each initial set temperature in accordance with the process procedure in S401 to S406 illustrated in <FIG> of the first embodiment. Then, the set temperature determining unit <NUM> specifies the plasticizing time shorter than the cooling time from the plurality of measured plasticizing times, and determines the initial set temperature corresponding to the plasticizing time, as the set temperature. When there are the plurality of plasticizing times shorter than the cooling time, any desired plasticizing time may be specified from the plurality of plasticizing times. For example, the set temperature determining unit <NUM> may specify the longest plasticizing time from the plurality of plasticizing times shorter than the cooling time, and may determine the initial set temperature corresponding to the specified plasticizing time, as the set temperature. In the present modification example, a measurement time required for a measurement process is shorter than the cooling time. Therefore, a shortened cycle can be achieved. In addition, as the set temperature, the set temperature determining unit <NUM> determines the initial set temperature corresponding to the longest plasticizing time (that is, the lowest initial set temperature) from the initial set temperatures corresponding to the plasticizing time shorter than the cooling time. In this manner, electric power supplied to the heating unit can be reduced. Therefore, energy saving can be achieved.

In the above-described embodiment, a case has been described where the plasticizing time is controlled to be shortest by improving the molten state of the resin. However, in some situations, the plasticizing time may be delayed depending on a usage mode. For example, the cooling time may be relatively long in some cases. Therefore, in the second embodiment, an example will be described where the plasticizing time is adjusted by adjusting the rotation speed of the screw <NUM> in view of the cooling time.

<FIG> is a functional block diagram illustrating components of the control device <NUM> according to the present embodiment. As illustrated in <FIG>, as in the first embodiment, the control device <NUM> includes the acquisition unit <NUM>, the plasticizing processing unit <NUM>, the plasticizing time measurement unit <NUM>, the filling processing unit <NUM>, the initial set temperature setting unit <NUM>, the set temperature determining unit <NUM>, and the temperature control processing unit <NUM>, and further includes the rotation speed setting unit <NUM>. In the present embodiment, the same reference numerals will be assigned to the same configurations as those in the first embodiment, and description thereof will be omitted.

Therefore, the rotation speed setting unit <NUM> according to the present embodiment sets the rotation speed of the screw <NUM>, based on the plurality of plasticizing times measured when the plasticizing process is performed on each of the plurality of different initial set temperatures in the cylinder <NUM>, and the cooling time until the depressurizing process of lowering the mold clamping force starts after the holding pressure process of holding the pressure to press the molding material remaining in the cylinder <NUM> toward the mold unit <NUM> is completed. In other words, the present embodiment is an example of adjusting the rotation speed of the screw <NUM> instead of shortening the plasticizing time, when the set temperature is specified.

<FIG> is a flowchart illustrating a process of setting the set temperature in the first zone Z1 and adjusting the rotation speed in the injection molding machine <NUM> according to the present embodiment. In an example illustrated in <FIG>, an example of setting the set temperature of the first zone Z1 will be described. However, the same control may be performed on other zones (for example, the <NUM>-th zone Z0 and the second zone Z2). When the set temperature is set for the <NUM>-th zone Z0, the cooler <NUM> is controlled instead of the heating unit 313_1. In the present embodiment, only the set temperature and the rotation speed are changed, and the processes are performed after other conditions (for example, conditions such as the position of the cylinder <NUM>) are fixed.

In the process illustrated in <FIG>, first, the initial set temperature setting unit <NUM> sets the initial value of the initial set temperature of the first zone Z1, and the rotation speed setting unit <NUM> sets the initial value of the initial rotation speed of the screw <NUM> (S801). The initial value may be determined depending on a usage mode and a molding material, or may be input by a user.

Thereafter, the same processes as those in S402 to S410 are performed in the same manner as in the first embodiment. In this manner, the set temperature determining unit <NUM> determines the set temperature (S802 to S810).

Then, the rotation speed setting unit <NUM> determines whether or not the plasticizing time in the current plasticizing process is equal to or shorter than the cooling time until the depressurizing process starts after the holding pressure process is completed in the mold unit <NUM> (S811). When it is determined that the plasticizing time in the plasticizing process is longer than the cooling time (S811: No), the rotation speed setting unit <NUM> performs control to raise the initial rotation speed (S812), and performs the process again from S811.

On the other hand, when the rotation speed setting unit <NUM> determines that the plasticizing time in the current plasticizing process is equal to or shorter than the cooling time until the depressurizing process starts after the holding pressure process is completed in the mold unit <NUM> (S811: Yes), the rotation speed setting unit <NUM> determines the initial rotation speed which is the plasticizing time equal to or shorter than the cooling time, as the set rotation speed (S813). In the subsequent plasticizing process, the control device <NUM> controls the screw <NUM> to rotate at the set rotation speed.

In the injection molding machine <NUM> according to the present embodiment, the same advantageous effect as that of the first embodiment can be achieved.

An example has been described as follows. In the vicinity of the root of the cylinder <NUM> from the resin feed port into which the resin pellet of the cylinder <NUM> is loaded in the injection molding machine <NUM> of the above-described embodiment (for example, a section including the supply zone 330a of the <NUM>-th zone Z0 to the second zone Z2), the heating units 313_1 to 313_2 and the cooler <NUM> are controlled in accordance with the set temperature set in the above-described processes. However, the above-described embodiment is not limited to the method of determining the set temperature only in the vicinity of the root of the cylinder <NUM> from the resin feed port (for example, the section including the supply zone 330a of the <NUM>-th zone Z0 to the second zone Z2).

For example, the set temperature may be determined by using the method of the above-described embodiment for the zones (for example, the zones Z0 to Z3) in which the resin pellet remains solid inside the cylinder <NUM> (in which the solid molding material exist). As the zones in which the resin pellet remains solid inside the cylinder <NUM> (in which the solid molding material exists) is, for example, it is conceivable to adopt for the <NUM>-th zone Z0 to the third zone Z3 including an end of the compression zone 330b which is a section for the screw <NUM> to compress the molding material when the plasticizing process starts, from a loading port of the resin pellet. As another example, the set temperature may be determined only in the <NUM>-th zone Z0, the set temperature may be determined only in the first zone Z1, the set temperature may be determined only in the second zone Z2, or the set temperature may be determined only in the third zone Z3.

The molten state of the cylinder <NUM> can be improved by determining the above-described set temperature, and the set temperature can be automatically determined for each zone of the cylinder <NUM>. Therefore, a user's burden can be reduced.

Furthermore, the set temperature may be determined for the fourth zone Z4 or the fifth zone Z5 by using the method of the above-described embodiment. The set temperature is determined by using the above-described method. In this manner, the molten state of the molding material inside the cylinder <NUM> or the nozzle <NUM> can be improved, and the set temperature can be automatically determined for each zone of the cylinder <NUM>. Therefore, a user's burden can be reduced.

Claim 1:
An injection molding machine (<NUM>) comprising:
an injection unit (<NUM>) configured to fill a mold unit (<NUM>) with a molding material plasticized inside a cylinder (<NUM>); and
a control device (<NUM>) configured to control the injection unit (<NUM>),
characterized in that
the control device (<NUM>) includes
an initial set temperature setting unit (<NUM>) configured to set a plurality of initial set temperatures used to determine a set temperature for the cylinder (<NUM>) by raising the initial set temperature from an initial value of the initial set temperature, the initial value of the initial set temperature being determined depending on a usage mode and the molding material or being input by a user,
a plasticizing processing unit (<NUM>) configured to rotationally drive a screw (<NUM>) such that a plasticizing process of the molding material is performed, at each of the different initial set temperatures,
a plasticizing time measurement unit (<NUM>) configured to measure a plasticizing time during the plasticizing process performed by the plasticizing processing unit (<NUM>) for each of the initial set temperatures, and
a set temperature determining unit (<NUM>) configured to determine the set temperature for the cylinder (<NUM>), based on a plurality of the plasticizing times measured for each of the initial set temperatures by the plasticizing measurement unit (<NUM>).