Patent Description:
An injection unit of an injection molding machine disclosed in <CIT> includes a cylinder that heats a molding material, a screw disposed to be rotatable and freely advanced and retreated inside the cylinder, a plasticizing motor that rotates the screw, an injection motor that advances and retreats the screw, and an injection frame to which the cylinder is fixed. The plasticizing motor and the injection motor are fixed to the injection frame. Therefore, when the injection motor advances and retreats the screw, a drive target to be advanced and retreated by the injection motor does not include the plasticizing motor. Therefore, an inertia of the drive target of the injection motor is small, and acceleration/deceleration of the screw is fast.

An injection molding machine comprising a cylinder, a screw that is rotatable and freely advanced and retreated inside the cylinder, a plasticizing motor configured to rotate the screw, a rotation transmission mechanism configured to transmit a rotation force of the plasticizing motor to the screw, and an injection frame to which the cylinder is fixed is known from the <CIT>, <CIT>, <CIT>, and <CIT>. Furthermore, <CIT> discloses an injection molding machine with a ball screw mechanism, and <CIT> discloses an injection molding machine applying a pressure sensor.

A rotor of the plasticizing motor disclosed in <CIT> includes a hollow shaft. Inside the hollow shaft, a mechanism is provided that transmits a rotation force of the plasticizing motor to the screw and allows the screw to be advanced and retreated with respect to the rotor of the plasticizing motor.

In the related art, many components are packed inside the hollow shaft of a plasticizing motor, and it is difficult to have an access to each of the components. In addition, in the related art, an inner diameter of the hollow shaft is large, and the plasticizing motor increases in size. Consequently, cost of the plasticizing motor is high.

One aspect of the present invention is to provide a technique for reducing cost of a plasticizing motor by improving an access to a component of an injection unit.

The aforementioned objective is achieved by injection molding machines according to the independent claims.

According to one aspect of the present invention, there is provided an injection molding machine including a cylinder, a screw, a plasticizing motor, a rotation transmission mechanism, and an injection frame, according to claim <NUM> or <NUM>. The cylinder heats a molding material. The screw is provided to be rotatable and freely advanced and retreated inside the cylinder. The plasticizing motor rotates the screw. The rotation transmission mechanism transmits a rotation force of the plasticizing motor to the screw, and allows the screw to be advanced and retreated with respect to the plasticizing motor. The cylinder is fixed to the injection frame. The plasticizing motor is fixed to the injection frame. The rotation transmission mechanism includes a spline. A rotation center line of the screw and a rotation center line of the spline are shifted in parallel.

According to one aspect of the present invention, the rotation center line of the screw and the rotation center line of the spline are shifted in parallel. In this manner, the number of components disposed on the same straight line as the rotation center line of the screw can be reduced, and an access to each of the components can be improved. In addition, the rotation center line of the screw and the rotation center line of the spline are shifted in parallel. In this manner, many components may not be packed inside a rotor of the plasticizing motor. Accordingly, the plasticizing motor can be miniaturized, and cost of the plasticizing motor can be reduced.

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

<FIG> is a view illustrating a state when mold opening is completed in an injection molding machine according to an embodiment. <FIG> is a view illustrating a state when mold clamping is performed in the injection molding machine according to the 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 position 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 unit. 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 a molding material. 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 measuring 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 sectional view illustrating a state when filling starts in the injection unit according to the embodiment. <FIG> is a sectional view illustrating a state when the filling is completed in the injection unit according to the embodiment. As described above, in describing the injection unit <NUM>, a moving direction of the screw <NUM> during the filling (for example, a negative direction of the X-axis) will be defined as forward, and a moving direction of the screw <NUM> during the plasticizing (for example, a positive direction of the X-axis) will be defined as rearward.

The injection unit <NUM> includes a cylinder <NUM> that heats a molding material, a screw <NUM> provided to be rotatable and freely advanced and retreated inside the cylinder <NUM>, a plasticizing motor <NUM> that rotates the screw <NUM>, an injection motor <NUM> (refer to <FIG> and <FIG>) that advances and retreats the screw <NUM>, a load detector <NUM> that measures a load transmitted between the screw <NUM> and the injection motor <NUM>, and a rotation transmission mechanism <NUM> that transmits a rotation force (torque) of the plasticizing motor <NUM> to the screw <NUM> and allows the screw <NUM> to be advanced and retreated with respect to the plasticizing motor <NUM>.

The injection unit <NUM> includes an injection frame <NUM> to which the cylinder <NUM> is fixed. For example, the injection frame <NUM> includes a front support <NUM> to which the cylinder <NUM> is attached, a rear support <NUM> provided behind the front support <NUM>, and a base <NUM> that supports the front support <NUM> and the rear support <NUM>. The front support <NUM> and the rear support <NUM> are fixed onto the base <NUM>. The base <NUM> is fixed to the slide base <NUM> (refer to <FIG> and <FIG>). The base <NUM> may be a portion of the slide base <NUM>.

The plasticizing motor <NUM> is fixed to the injection frame <NUM>. The plasticizing motor <NUM> is attached to the rear support <NUM> in <FIG> and <FIG>, but may be attached to the front support <NUM> or the base <NUM>. In addition, although not illustrated, the injection motor <NUM> is also fixed to the injection frame <NUM>. For example, the injection motor <NUM> is attached to the base <NUM>.

As described above, the plasticizing motor <NUM> is fixed to the injection frame <NUM>. Therefore, when the injection motor <NUM> advances and retreats the screw <NUM>, a drive target to be advanced and retreated by the injection motor <NUM> does not include the plasticizing motor <NUM>. Therefore, an inertia of the drive target of the injection motor <NUM> is small, and the acceleration/deceleration of the screw <NUM> is fast.

The rotation transmission mechanism <NUM> transmits the rotation force of the plasticizing motor <NUM> to the screw <NUM>, and allows the screw <NUM> to be advanced and retreated with respect to the plasticizing motor <NUM>. Specifically, the rotation transmission mechanism <NUM> includes a spline <NUM>. The spline <NUM> includes a spline shaft <NUM> and a spline nut <NUM> that transmits the rotation force between to the spline shaft <NUM> and relatively moves in the axial direction of the spline shaft <NUM>. External teeth formed on the outer periphery of the spline shaft <NUM> and internal teeth formed on the inner periphery of the spline nut <NUM> mesh with each other. A ball or a roller may be interposed between the spline shaft <NUM> and the spline nut <NUM>.

For example, as illustrated in <FIG> and <FIG>, the spline shaft <NUM> is fixed to a rotor of the plasticizing motor <NUM>, and the spline nut <NUM> is advanced and retreated together with the screw <NUM>. The spline <NUM> can transmit the rotation force of the plasticizing motor <NUM> to the screw <NUM>, and can advance and retreat the screw <NUM> in a state where the plasticizing motor <NUM> is fixed to the screw <NUM>.

A rotation center line R1 of the screw <NUM> and a rotation center line R2 of the spline <NUM> are shifted in parallel. That is, the rotation center lines R1 and R2 are parallel, and are shifted in directions perpendicular to the respective axial directions. For example, the rotation center lines R1 and R2 are horizontal, and the rotation center line R2 is shifted upward of the rotation center line R1.

The rotation center line R1 of the screw <NUM> and the rotation center line R2 of the spline <NUM> are shifted in parallel. In this manner, the number of components disposed on the same straight line as the rotation center line R1 of the screw <NUM> can be reduced, and an access to each of the components can be improved. In addition, the rotation center line R1 of the screw <NUM> and the rotation center line R2 of the spline <NUM> are shifted in parallel. In this manner, many components may not be packed inside the rotor of the plasticizing motor <NUM>. Accordingly, the plasticizing motor <NUM> can be miniaturized, and cost of the plasticizing motor <NUM> can be reduced. In addition, the rotation center line R1 of the screw <NUM> and the rotation center line R2 of the spline <NUM> are shifted in parallel. In this manner, a transmission <NUM> (to be described later) can be installed.

The rotation transmission mechanism <NUM> includes the transmission <NUM> that changes and transmits the rotation speed from the spline <NUM> to the extension shaft <NUM> of the screw <NUM>. For example, the transmission <NUM> is a speed reducer, and reduces and transmits the rotation speed from the spline <NUM> to the extension shaft <NUM> of the screw <NUM>. A rotation force (torque) proportional to a reduction ratio of the speed reducer can be obtained, and the plasticizing motor <NUM> can be miniaturized.

For example, the transmission <NUM> includes a driving pulley <NUM> fixed to the spline <NUM>, a driven pulley <NUM> fixed to the extension shaft <NUM> of the screw <NUM>, and a belt <NUM> laid between the driving pulley <NUM> and the driven pulley <NUM>. For example, the driving pulley <NUM> is fixed to the spline shaft <NUM>. For example, the belt <NUM> is an endless belt. When the transmission <NUM> is the speed reducer, a radius of the driven pulley <NUM> is larger than a radius of the driving pulley <NUM>. A value obtained by dividing the radius of the driven pulley <NUM> by the radius of the driving pulley <NUM> is the reduction ratio.

Although not illustrated, the transmission <NUM> may include a driving gear fixed to the spline <NUM> and a driven gear fixed to the extension shaft <NUM> of the screw <NUM>. The driving gear and the driven gear mesh with each other to transmit the rotation force. When the transmission <NUM> is the speed reducer, the radius of the driven gear is larger than the radius of the driving gear. A value obtained by dividing the radius of the driven gear by the radius of the driving gear is the reduction ratio. An intermediate gear may be provided between the driving gear and the driven gear.

For example, the injection unit <NUM> may include a linear motion unit <NUM> freely advanced and retreated with respect to the injection frame <NUM>, an injection motor <NUM> that advances and retreats the screw <NUM> via the linear motion unit <NUM>, and a motion conversion mechanism <NUM> that converts a rotary motion of the injection motor <NUM> into a linear motion of the linear motion unit <NUM>.

For example, the linear motion unit <NUM> is provided between the front support <NUM> and the rear support <NUM>. The linear motion unit <NUM> is advanced and retreated in the X-axial direction along the guide rail <NUM> fixed onto the base <NUM>. The guide rail <NUM> restricts the rotation of the linear motion unit <NUM> so that the linear motion unit <NUM> is not rotated by the rotation force of the plasticizing motor <NUM>. For example, the linear motion unit <NUM> includes a slider <NUM> advanced and retreated in the X-axial direction along the guide rail <NUM>.

Although not illustrated, the linear motion unit <NUM> may be advanced and retreated in the X-axial direction along a guide bar laid between the front support <NUM> and the rear support <NUM>. In this case, the guide bar also restricts the rotation of the linear motion unit <NUM> so that the linear motion unit <NUM> is not rotated by the rotation force of the plasticizing motor <NUM>.

The linear motion unit <NUM> includes a first bearing holder <NUM> that holds a first bearing <NUM> for supporting the spline <NUM> to be rotatable, and a second bearing holder <NUM> that holds a second bearing <NUM> for supporting the screw <NUM> to be rotatable. The first bearing <NUM> can prevent transmission of the rotation force from the spline <NUM> to the linear motion unit <NUM>. In addition, the second bearing <NUM> can prevent transmission of the rotation force from the screw <NUM> to the linear motion unit <NUM>. In addition, the first bearing <NUM> and the second bearing <NUM> are separately provided. Accordingly, a difference in the rotation speed between the spline <NUM> and the screw <NUM> can be made.

For example, the first bearing <NUM> supports the spline nut <NUM> to be rotatable. For example, the first bearings <NUM> are provided across the belt <NUM> on both sides (both front side and rear side) of the spline nut <NUM> in the axial direction. Inclination of the spline nut <NUM> which is caused by tension of the belt <NUM> can be suppressed, compared to a case where the first bearing <NUM> is provided on only one side of the belt <NUM>.

The first bearing holder <NUM> includes a front holder 384a that holds the first bearing <NUM> in front of the belt <NUM>, a rear holder 384b that holds the first bearing <NUM> behind the belt <NUM>, and a connecting portion 384c that connects the front holder 384a and the rear holder 384b. When the first bearing <NUM> is provided on only one side of the belt <NUM>, the first bearing holder <NUM> may include only one of the front holder 384a and the rear holder 384b.

For example, the second bearing <NUM> supports the screw <NUM> to be rotatable, thereby supporting the extension shaft <NUM> of the screw <NUM> to be rotatable. A plurality of the second bearings <NUM> may be provided at an interval along the extension shaft <NUM>. An inner ring spacer <NUM> that presses an inner ring of the second bearing <NUM> is provided between the second bearings <NUM> adjacent to each other. The inner ring spacer <NUM> is fixed to an outer periphery of the extension shaft <NUM>.

For example, the extension shaft <NUM> of the screw <NUM> includes an attachment portion <NUM> to which the rear end of the screw <NUM> is attached, and a rotating portion <NUM> supported to be rotatable by the second bearing <NUM>. Not only the screw <NUM> but also the driven pulley <NUM> or the driven gear may be attached to the attachment portion <NUM>. For example, the rotating portion <NUM> is a hollow shaft. When the rotating portion <NUM> is the hollow shaft, a front end portion of the ball screw shaft <NUM> of the motion conversion mechanism <NUM> can be accommodated inside the rotating portion <NUM>, as illustrated in <FIG>. For example, when the rotating portion <NUM> is retreated, the front end portion of the ball screw shaft <NUM> may be inserted into the rotating portion <NUM>. Compared to a case where the rotating portion <NUM> is a solid shaft, an interval between the ball screw nut <NUM> and the rotating portion <NUM> can be shortened, and a dimension of the injection unit <NUM> in the X-axial direction can be shortened.

The second bearing holder <NUM> is fixed to the slider <NUM>. The second bearing holder <NUM> includes an insertion hole 386a into which the extension shaft <NUM> of the screw <NUM> is inserted. The rotating portion <NUM> of the extension shaft <NUM> is disposed in the insertion hole 386a. The rotating portion <NUM> is disposed inside the insertion hole 386a not to interfere with the load detector <NUM>.

For example, the motion conversion mechanism <NUM> includes a ball screw <NUM>. The ball screw <NUM> includes a ball screw shaft <NUM> and a ball screw nut <NUM> screwed to the ball screw shaft <NUM>. The ball screw nut <NUM> is fixed to the linear motion unit <NUM> via the load detector <NUM>.

On the other hand, the ball screw shaft <NUM> is attached to the injection frame <NUM> via a bearing <NUM> that supports the ball screw shaft <NUM> to be rotatable. For example, an outer ring of the bearing <NUM> is fixed to the rear support <NUM> of the injection frame <NUM>, and an inner ring of the bearing <NUM> is fitted into a groove <NUM> of the ball screw shaft <NUM>.

The ball screw shaft <NUM> is ejected rearward from the rear support <NUM> of the injection frame <NUM>. For example, a rotation transmission mechanism <NUM> that transmits the rotation force of the injection motor <NUM> to the ball screw <NUM> is provided in a rear end portion of the ball screw shaft <NUM>.

For example, the rotation transmission mechanism <NUM> includes a driving pulley fixed to an output shaft of the injection motor <NUM>, a driven pulley <NUM> fixed to the rear end portion of the ball screw shaft <NUM>, and a belt laid between the driving pulley and the driven pulley <NUM>. The rotation transmission mechanism <NUM> may include a driving gear and a driven gear, instead of the driving pulley, the driven pulley <NUM>, and the belt.

The rotation transmission mechanism <NUM> may not be provided, and the output shaft of the injection motor <NUM> and the ball screw shaft <NUM> may be disposed on the same straight line R1 to be directly connected to each other.

When the control device <NUM> operates the injection motor <NUM>, the ball screw shaft <NUM> is rotated, and the ball screw nut <NUM> is advanced and retreated in the X-axial direction. As a result, the linear motion unit <NUM> and the screw <NUM> are advanced and retreated in the X-axial direction.

The load detector <NUM> measures a load transmitted between the injection motor <NUM> and the screw <NUM>. For example, the load detector <NUM> is provided between the ball screw nut <NUM> and the linear motion unit <NUM>. Since the load detector <NUM> is provided, it is possible to measure a pressure received from the molding material by the screw <NUM>, a back pressure acting on the screw <NUM>, a pressure acting on the molding material from the screw <NUM>.

For example, the load detector <NUM> is a ring type, and includes an outer peripheral ring <NUM>, an inner peripheral ring <NUM> disposed inside the outer peripheral ring <NUM> in the radial direction, and a strain element <NUM> that connects the outer peripheral ring <NUM> and the inner peripheral ring <NUM>. The load detector <NUM> detects a shear strain of the strain element <NUM>, and transmits an electric signal corresponding to a magnitude of the shear strain to the control device <NUM>.

For example, the outer peripheral ring <NUM> of the load detector <NUM> is fixed to a rear end surface of the second bearing holder <NUM> of the linear motion unit <NUM>. On the other hand, the inner peripheral ring <NUM> of the load detector <NUM> is fixed to a front end surface of the ball screw nut <NUM>. The load detector <NUM> is not limited to the ring type, and may be a compression type, for example.

Next, the injection unit <NUM> according to a first modification example will be described with reference to <FIG> and <FIG>. <FIG> is a sectional view illustrating a state when filling starts in the injection unit according to the first modification example. <FIG> is a sectional view illustrating a state when the filling is completed in the injection unit according to the first modification example. Hereinafter, different points between the first modification example and the above-described embodiment will be mainly described.

As illustrated in <FIG> and <FIG>, the spline nut <NUM> may be fixed to the rotor of the plasticizing motor <NUM>, and the spline shaft <NUM> may be advanced and retreated together with the screw <NUM>. In this case, the spline <NUM> can also transmit the rotation force of the plasticizing motor <NUM> to the screw <NUM>, and the screw <NUM> can be advanced and retreated in a state where the plasticizing motor <NUM> is fixed to the screw <NUM>.

In the present modification example, as in the above-described embodiment, the rotation center line R1 of the screw <NUM> and the rotation center line R2 of the spline <NUM> are also shifted in parallel. Therefore, the number of components disposed on the same straight line as the rotation center line R1 of the screw <NUM> can be reduced, and an access to each of the components can be improved. In addition, many components may not be packed inside the rotor of the plasticizing motor <NUM>. Accordingly, the plasticizing motor <NUM> can be miniaturized, and cost of the plasticizing motor <NUM> can be reduced. In addition, the transmission <NUM> can be installed.

The rotation transmission mechanism <NUM> includes the transmission <NUM> that changes and transmits the rotation speed from the spline <NUM> to the extension shaft <NUM> of the screw <NUM>. The driving pulley <NUM> of the transmission <NUM> is fixed to the spline nut <NUM> in the above-described embodiment, but is fixed to the spline shaft <NUM> in the present modification example. In this case, the rotation speed can be changed and transmitted from the spline <NUM> to the extension shaft <NUM> of the screw <NUM>.

The first bearing <NUM> supports the spline nut <NUM> to be rotatable in the above-described embodiment, but supports the spline shaft <NUM> to be rotatable in the present modification example. For example, the first bearings <NUM> are provided across the belt <NUM> on both sides (both front side and rear side) of the spline shaft <NUM> in the axial direction. Inclination of the spline nut <NUM> which is caused by tension of the belt <NUM> can be suppressed, compared to a case where the first bearing <NUM> is provided on only one side of the belt <NUM>.

Next, the injection unit <NUM> according to a second modification example will be described with reference to <FIG> and <FIG>. <FIG> is a sectional view illustrating a state when filling starts in the injection unit according to the second modification example. <FIG> is a sectional view illustrating a state when the filling is completed in the injection unit according to the second modification example. Hereinafter, different points between the second modification example and the above-described embodiment will be mainly described.

For example, the motion conversion mechanism <NUM> includes a ball screw <NUM>. The ball screw <NUM> includes a ball screw shaft <NUM> and a ball screw nut <NUM> screwed to the ball screw shaft <NUM>. For example, the ball screw nut <NUM> is fixed to the rear support <NUM> of the injection frame <NUM> via the load detector <NUM>.

For example, the rear end portion of the ball screw shaft <NUM> is spline-coupled to the rotor of the injection motor <NUM>. The rotation center line of the ball screw shaft <NUM> and the rotation center line of the injection motor <NUM> are disposed on the same straight line R1. For example, the injection motor <NUM> is fixed to the rear support <NUM> of the injection frame <NUM>.

The rotation center line of the ball screw shaft <NUM> and the rotation center line of the injection motor <NUM> are disposed on the same straight line R1 in the present modification example, but both of these may be disposed to be shifted in parallel. In the latter case, the output shaft of the injection motor <NUM> and the spline nut are connected by a pulley and a belt, and the spline nut and the spline shaft provided in the rear end of the ball screw shaft <NUM> are fitted to each other.

On the other hand, the front end portion of the ball screw shaft <NUM> is attached to the rotating portion <NUM> via the bearing <NUM> that supports a front end portion thereof to be rotatable. For example, the rotating portion <NUM> is a hollow shaft. The outer ring of the bearing <NUM> is fixed to the rotating portion <NUM>, and the inner ring of the bearing <NUM> is fitted into the groove <NUM> of the ball screw shaft <NUM>.

When the control device <NUM> operates the injection motor <NUM>, the ball screw shaft <NUM> is advanced and retreated while being rotated. As a result, the linear motion unit <NUM> and the screw <NUM> are advanced and retreated.

For example, the load detector <NUM> is provided in front of the rear support <NUM> of the injection frame <NUM>. In this case, the outer peripheral ring <NUM> of the load detector <NUM> is fixed to the front end surface of the rear support <NUM> of the injection frame <NUM>, and the inner peripheral ring <NUM> of the load detector <NUM> is fixed to the rear end surface of the ball screw nut <NUM>.

The load detector <NUM> may be provided behind the rear support <NUM> of the injection frame <NUM>. In this case, the outer peripheral ring <NUM> of the load detector <NUM> is fixed to the rear end surface of the rear support <NUM> of the injection frame <NUM>, and the inner peripheral ring <NUM> of the load detector <NUM> is fixed to the rear end surface of the ball screw nut <NUM>. In addition, in this case, the injection motor <NUM> is fixed to the rear support <NUM> via the outer peripheral ring <NUM> of the load detector <NUM>.

Claim 1:
An injection molding machine (<NUM>) comprising:
a cylinder (<NUM>) configured to heat a molding material;
a screw (<NUM>) provided to be rotatable and freely advanced and retreated inside the cylinder (<NUM>);
a plasticizing motor (<NUM>) configured to rotate the screw (<NUM>);
a rotation transmission mechanism (<NUM>) configured to transmit a rotation force of the plasticizing motor (<NUM>) to the screw (<NUM>); and
an injection frame (<NUM>) to which the cylinder (<NUM>) is fixed; and
the plasticizing motor (<NUM>) is fixed to the injection frame (<NUM>),
the rotation transmission mechanism (<NUM>) includes a spline (<NUM>),
a rotation center line (R1) of the screw (<NUM>) and a rotation center line (R2) of the spline (<NUM>) are shifted in parallel,
characterized in that
the spline (<NUM>) includes a spline shaft (<NUM>) and a spline nut (<NUM>) configured to transmit the rotation force to the spline shaft (<NUM>) and relatively move in an axial direction of the spline shaft (<NUM>),
the spline shaft (<NUM>) is fixed to a rotor of the plasticizing motor (<NUM>), and
the spline nut (<NUM>) is advanced and retreated together with the screw (<NUM>) with respect to the plasticizing motor (<NUM>).