THREE DIMENSIONAL MOLDING DEVICE

This three dimensional molding device includes a plasticizing section having a screw in which a groove is formed and generating a plasticized material by plasticizing a material by rotating the screw; a nozzle having a nozzle opening and ejecting the plasticized material; an ejection adjustment section provided in a flow path, which communicates with the nozzle opening, and adjusting an ejecting amount of the plasticized material from the nozzle by adjusting an opening area of the flow path; and a control section, wherein the control section controls a rotation speed of the screw at a first rotation speed when the opening area is a first opening area and controls the rotation speed of the screw at a second rotation speed that is faster than the first rotation speed when the opening area is a second opening area that is larger than the first opening area.

The present application is based on, and claims priority from JP Application Serial Number 2022-157651, filed Sep. 30, 2022, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a three dimensional molding device and a method for manufacturing a three dimensional molded object.

2. Related Art

JP-A-2022-16532 discloses a three dimensional molding device including a butterfly valve as a flow amount adjustment mechanism for adjusting the ejecting amount of a molten material from a nozzle.

When the ejecting amount is decreased by a flow amount adjustment mechanism such as a butterfly valve, pressure in the flow path upstream of the flow amount adjustment mechanism increases as time elapses. Therefore, when the ejecting amount is increased by the flow amount adjustment mechanism after the ejecting amount is decreased, an unexpected ejecting amount of molten material is ejected from the nozzle due to increased pressure, molding accuracy is affected.

SUMMARY

According to a first aspect of the present disclosure, a three dimensional molding device is provided.

This three dimensional molding device includes a plasticizing section that has a screw in which a groove is formed and that is configured to generate a plasticized material by plasticizing a material by rotating the screw; a nozzle that has a nozzle opening and that is configured to eject the plasticized material; a table on which the plasticized material ejected from the nozzle is deposited; a position changing section configured to change a relative position between the nozzle and the table; an ejection adjustment section that is provided in a flow path, which communicates with the nozzle opening and through which the plasticized material flows, and that is configured to adjust an ejecting amount of the plasticized material from the nozzle by adjusting an opening area of the flow path; and a control section configured to mold a three dimensional molded object in a molding area of the table by controlling the plasticizing section, the position changing section, and the ejection adjustment section, wherein the control section controls a rotation speed of the screw at a first rotation speed when the opening area of the flow path is a first opening area and controls the rotation speed of the screw at a second rotation speed that is faster than the first rotation speed when the opening area of the flow path is a second opening area that is larger than the first opening area.

According to a second aspect of the present disclosure, there is provided a method for manufacturing a three dimensional molded object.

This manufacturing method includes a first step of plasticizing a material by rotating a screw, in which a groove is formed, to generate a plasticized material and a second step of molding a three dimensional molded object by discharging the plasticized material from a nozzle having a nozzle opening, wherein the second step includes a step of adjusting an ejecting amount of the plasticized material from the nozzle by adjusting an opening area of a flow path which communicates with the nozzle opening and through which the plasticized material flows and the first step includes a step of setting the rotation speed of the screw to a first rotation speed when the opening area of the flow path is a first opening area and setting the rotation speed of the screw to a second rotation speed that is higher than the first rotation speed when the opening area of the flow path is second opening area that is larger than the first opening area.

DESCRIPTION OF EMBODIMENTS

A. First Embodiment

FIG.1is an explanatory view showing a schematic configuration of a three dimensional molding device100according to a first embodiment. InFIG.1, arrows indicating X, Y, and Z directions orthogonal to each other are shown. The X direction and the Y direction are directions parallel to a horizontal plane, and the Z direction is a direction along a vertically upward direction. The arrows indicating the X, Y, and Z directions are appropriately illustrated in other drawings so that the illustrated directions correspond to those inFIG.1. In the following description, when a direction to be specified, a direction indicated by an arrow in each drawing is referred to as “+” and an opposite direction is referred to as “−”, and positive and negative signs are used in combination for direction notation. Hereinafter, the +Z direction is also referred to as “upper”, and the −Z direction is also referred to as “lower”.

The three dimensional molding device100of the present embodiment is a device that molds a molded object by a material extrusion method. The three dimensional molding device100includes a molding section110that generates and ejects a plasticized material, a table210for molding serving as a base of a molded object, a position changing section230that controls an eject position of the plasticized material, and a control section300that controls each unit of the three dimensional molding device100.

Under the control of the control section300, the molding section110ejects a plasticized material obtained by plasticizing a material in a solid state onto the table210. The molding section110includes a material supply section20that is a supply source of a raw material before being converted into the plasticized material, a plasticizing section30that converts the raw material into the plasticized material, and an ejection section60that ejects the plasticized material.

The material supply section20supplies a raw material MR to the plasticizing section30. The material supply section20is constituted by, for example, a hopper for containing the raw material MR. The material supply section20is connected to the plasticizing section30via a communication path22. The raw material MR is supplied to the material supply section20in the form of pellets, powder, or the like. As the raw material, for example, a resin material such as ABS (acrylonitrile-butadiene-styrene), PEEK (polyetheretherketone), or PP (polypropylene) is used.

The plasticizing section30plasticizes the raw material MR supplied from the material supply section20to generate a pasty plasticized material exhibiting fluidity, and guides the plasticized material to the ejection section60. In the present embodiment, “plasticization” is a concept that includes melting and is a change from a solid to a fluid state. Specifically, in the case of a material that undergoes a glass transition, plasticization means that the temperature of the material is set to be equal to or higher than its glass transition point. In the case of a material that does not undergo glass transition, plasticization means that the temperature of the material is set to be equal to or higher than its melting point.

The plasticizing section30includes a screw case31, a drive motor32, a flat screw40, and a barrel50. The flat screw40is also referred to as a rotor or simply a screw. The barrel50is also referred to as a screw facing section.

FIG.2is a perspective view showing a schematic configuration of a lower surface48side of the flat screw40. In order to facilitate understanding of the technology, the flat screw40shown inFIG.2is shown in a state in which the positional relationship between an upper surface47and the lower surface48shown inFIG.2is reversed in the vertical direction.FIG.3is a schematic plan view showing the upper surface52side of the barrel50. The flat screw40has a substantially columnar shape in which a length in an axial direction, which is a direction along a central axis, is smaller than a length in a direction perpendicular to the axial direction. The flat screw40is disposed such that a rotation axis RX, which is its center of rotation, is parallel to the Z direction.

As shown inFIG.1, the flat screw40is housed in the screw case31. The upper surface47of the flat screw40is connected to the drive motor32, and the flat screw40is rotated in the screw case31by a rotational driving force generated by the drive motor32. The rotation speed of the flat screw40is controlled by the control section300. The flat screw40may be driven by the drive motor32via a reduction gear.

As shown inFIG.2, vortex shaped groove sections42are formed on the lower surface48of the flat screw40, which is a surface intersecting the rotation axis RX. The communication path22of the material supply section20described above communicates with the groove sections42from the side surface of the flat screw40. In the present embodiment, the groove sections42are separated from each other by the ridge sections43, and three groove sections42are formed. The number of the groove sections42is not limited to three, and may be one or two or more. The groove sections42are not limited to a vortex shape, but may be a spiral shape or an involute curve shape, or may be a shape extending so as to draw an arc from the central section toward the outer periphery.

The lower surface48of the flat screw40faces the upper surface52of the barrel50, and space is formed between the groove sections42of the lower surface48of the flat screw40and the upper surface52of the barrel50. The raw material MR is supplied to the space between the flat screw40and the barrel50from the material supply section20through a material inflow port44(shown inFIG.2).

As shown inFIG.1, a barrel heater58for heating the raw material MR supplied into the groove sections42of the rotating flat screw40is embedded in the barrel50. A communication hole56is provided at the center of the barrel50. As shown inFIG.3, the upper surface52of the barrel50is formed with a plurality of guide grooves54that are connected to the communication hole56and that extend vortically from the communication hole56toward the outer periphery. One end of the guide grooves54may not be connected to the communication hole56. The guide grooves54may be omitted.

The raw material MR supplied into the groove sections42of the flat screw40flows along the groove sections42by the rotation of the flat screw40while being plasticized in the groove sections42, and is guided to a central section46of the flat screw40as a plasticized material. The plasticized material in a paste state exhibiting fluidity and which flowed into the central section46is supplied to the ejection section60via the communication hole56provided at the center of the barrel50. In the plasticized material, not all types of substances constituting the plasticized material need be plasticized. The plasticized material may be converted into a state having fluidity as a whole by plasticizing at least some types of substances among the substances constituting the plasticized material.

The ejection section60ofFIG.1includes a nozzle61that ejects the plasticized material from a nozzle opening62, a flow path65of the plasticized material provided between the flat screw40and the nozzle opening62, and an ejection control section77that controls ejection of the plasticized material.

The nozzle61is connected to the communication hole56of the barrel50through the flow path65. The nozzle61ejects the plasticized material generated in the plasticizing section30toward the table210from the nozzle opening62at the tip end.

The ejection control section77includes an ejection adjustment section70that opens and closes the flow path65and a suction section75that sucks and temporarily stores the plasticized material.

The ejection adjustment section70is provided in the flow path65which communicates with the nozzle opening62and through which the plasticized material flows. The ejection adjustment section70adjusts the ejecting amount of the plasticized material from the nozzle61by adjusting the opening area of the flow path65. The communication hole56formed in the barrel50is a part of the flow path65.

The ejection adjustment section70includes a drive shaft71, a butterfly valve72, an angle detection sensor73, and a first drive section74.

FIG.4is a perspective view showing a schematic configuration of the butterfly valve72. The drive shaft71is a shaft disposed along a direction intersecting the direction in which the flow path65extends. In the present embodiment, the flow path65extends along the Z direction, and the drive shaft71is disposed along the Y direction. The butterfly valve72is formed on a part of the drive shaft71in the flow path65. The butterfly valve72is a member obtained by processing a part of the drive shaft71. The butterfly valve72is rotatably disposed in the flow path65. The drive shaft71is provided so that the butterfly valve72is located at a position where the drive shaft71and the flow path65intersect with each other. The rotation angle of the butterfly valve72shown inFIG.4is an angle at which the opening area of the flow path65is zero. The shape of the butterfly valve72is not limited as long as it rotates in the flow path65to adjust the opening area of the flow path65, and may be, for example, a plate shape or a hemispherical shape. The butterfly valve72is also referred to as a valve.

The angle detection sensor73shown inFIG.1is a sensor for detecting the rotation angle of the butterfly valve72. As the angle detection sensor73, for example, a rotary encoder or a resolver can be used.

The first drive section74rotates the butterfly valve72by rotating the drive shaft71. The first drive section74is configured by, for example, a stepping motor. The control section300adjusts the opening area of the flow path65by controlling the rotation angle of the butterfly valve72using the first drive section74, and adjusts the flow amount of the plasticized material flowing from the plasticizing section30to the nozzle61, that is, the ejecting amount of the plasticized material ejected from the nozzle61. The control section300executes feedback control of the rotation angle of the butterfly valve72using the detection value of the angle detection sensor73. The ejection adjustment section70can adjust the ejecting amount of the plasticized material and can control ON/OFF of the outflow of the plasticized material.

In the adjustment of the opening area of the flow path65using the ejection adjustment section70, the control section300can execute either a process of changing the opening area at a first adjustment speed or a process of changing the opening area at a second adjustment speed that is higher than the first adjustment speed. That is, the control section300can adjust the opening area of the flow path65at least two stages of adjustment speeds. In the present embodiment, the process of changing the opening area is a process of driving the drive shaft71to rotate the butterfly valve72, and the adjustment speed is the rotation speed of the butterfly valve72.

The suction section75is connected between the ejection adjustment section70and the nozzle opening62in the flow path65. The suction section75temporarily sucks the plasticized material in the flow path65when ejection of the plasticized material from the nozzle61is stopped, thereby suppressing a tailing phenomenon in which the plasticized material drips threadlike from the nozzle opening62. In the present embodiment, the suction section75is constituted by a plunger. The suction section75is driven by the second drive section76under the control of the control section300. The second drive section76is configured by, for example, a stepping motor, a rack and pinion mechanism that converts rotational force of the stepping motor into translational motion of a plunger, or the like.

A pressure sensor80is provided in the flow path65. The pressure sensor80is provided in the flow path65upstream of the ejection adjustment section70. The pressure sensor80detects the pressure in the flow path65upstream of the ejection adjustment section70.

The table210is disposed at a position facing the nozzle opening62of the nozzle61. In the first embodiment, the molding surface211of the table210facing the nozzle opening62of the nozzle61is disposed to be parallel to the X and Y directions, that is, a horizontal direction. The table210may be provided with a heater for suppressing rapid cooling of the plasticized material ejected onto the table210.

The position changing section230changes the relative position between the table210and the nozzle61under the control of the control section300. In the present embodiment, the position of the nozzle61is fixed, and the position changing section230moves the table210. The position changing section230is configured by a three axis positioner that moves the table210in three axial directions of X, Y, and Z directions by driving forces of three motors. In the present specification, unless otherwise specified, the movement of the nozzle61means that the nozzle61or the ejection section60is moved relative to the table210.

In another embodiment, instead of the configuration in which the table210is moved by the position changing section230, a configuration may be employed in which the position changing section230moves the nozzle61with respect to the table210in a state in which the position of the table210is fixed. In addition, a configuration may be employed in which the table210is moved in the Z direction by the position changing section230and the nozzle61is moved in the X and Y directions, or a configuration in which the table210is moved in the X and Y directions by the position changing section230and the nozzle61is moved in the Z direction. Even in these configurations, the relative positional relationship between the nozzle61and the table210can be changed.

The control section300is configured by a computer that has one or a plurality of processors310, a storage section320that includes a main storage section and an auxiliary storage device, and an input/output interface that inputs and outputs signals to and from the outside. By executing a program stored in the storage section320, the processor310controls the plasticizing section30, the position changing section230, and the ejection control section77according to molding data stored in the storage section320, thereby molding the three dimensional molded object in the molding region of the table210. The molding data for molding the three dimensional molded object includes, for each layer of the molded object shaped sliced into a plurality of layers, path information representing a movement path of the nozzle61and ejecting amount information indicating the ejecting amount of the plasticized material in each movement path. The movement path of the nozzle61is a path in which the nozzle61relatively moves along the molding surface211of the table210while ejecting the plasticized material. The control section300may be realized by a configuration in which circuits are combined, instead of being configured by a computer.

FIG.5is an explanatory view schematically showing a basic operation in which the three dimensional molding device100molds the molded object. In the three dimensional molding device100, as described above, the raw material MR in a solid state is plasticized to generate the plasticized material MM. The control section300causes the nozzle61to eject plasticized material MM while changing the position of the nozzle61with respect to the table210in a direction along the molding surface211of the table210while maintaining the distance between the molding surface211of the table210and the nozzle61. The plasticized material MM ejected from the nozzle61is continuously deposited in the moving direction of the nozzle61.

The control section300repeats the movement of the nozzle61to form a molded layer ML. After forming one molded layer ML, the control section300relatively moves the position of the nozzle61with respect to the table210in the Z direction. Then, the molded object is formed by stacking further molded layers ML on the molded layers ML formed so far.

For example, in a case where the nozzle61is to be moved in the Z direction when one layer worth of the molded layers ML is completed, or in a case where there are a plurality of independent molding regions in each molded layer, in some case, the control section300temporarily stops ejection of the plasticized material from the nozzle61. In this case, the flow path65is closed by the ejection adjustment section70to stop ejection of the plasticized material MM from the nozzle opening62, and the plasticized material in the nozzle61is temporarily sucked by the suction section75. After changing the position of the nozzle61, the control section300causes the ejection adjustment section70to open the flow path65while ejecting the plasticized material in the suction section75, thereby resuming the deposition of the plasticized material MM from the changed position of the nozzle61.

FIG.6is a flowchart of a three dimensional molding process executed by the control section300. A method of manufacturing the three dimensional molded object is realized by executing the three dimensional molding process. While the three dimensional molding process is being executed, the control section300controls the plasticizing section30, the position changing section230, and the ejection adjustment section70in accordance with the molding data, thereby depositing the plasticized material on the table210and molding the three dimensional molded object.

In step S10, the control section300determines the opening area of the flow path65based on the ejecting amount information in the molding data. Specifically, the larger the ejecting amount, the larger the value that the control section300sets the opening area of the flow path65and the smaller the ejecting amount, the smaller the value that the control section300sets the opening area of the flow path65.

In step S12, the control section300determines the rotation speed of the flat screw40based on the opening area determined in step S10.

FIG.7is a graph showing the relationship between the opening area of the flow path65and the rotation speed of the flat screw40. As shown inFIG.7, the larger the opening area of the flow path65, the more the control section300increases the rotation speed of the flat screw40. For example, when the opening area of the flow path65is a second opening area S2, which is larger than a first opening area S1, the control section300determines the rotation speed of the screw case31is to be a second rotation speed R2, which is faster than a first rotation speed R1. The relationship between the opening area of the flow path65and the rotation speed of the flat screw40is determined in advance through experiments and simulations so that the amount of the plasticized material supplied to the ejection adjustment section70and the amount of the plasticized material flowing out from the ejection adjustment section70do not become excessive or deficient when the opening area of the flow path65is changed by the ejection adjustment section70.

In step S14ofFIG.6, the control section300controls the plasticizing section30to adjust the rotation speed of the flat screw40to the rotation speed determined in step S12.

After the adjustment of the rotation speed of the flat screw40, then in step S16, the control section300controls the ejection adjustment section70to adjust the opening area of the flow path65to the opening area determined in step S10.

FIG.8is a timing chart showing control timings of the flat screw40and the butterfly valve72. According to the above described step S14and step S16, in the present embodiment the control section300starts an operation for changing the rotation speed of the flat screw40earlier than an operation for changing the opening area of the flow path65. In the timing chart shown inFIG.8, the control section300starts the operation for changing the rotation speed of the flat screw40at timing T1, and starts the operation for changing the rotation angle of the butterfly valve72at timing T2, which is later than timing T1. The difference between the timing T1at which the rotation speed of the flat screw40is changed and the timing T2at which the opening area of the flow path65is subsequently changed is desirably set by executing experiments or simulations in advance to be a timing at which the plasticized material, in a generation amount that was increased or decreased by changing the rotation speed of the flat screw40, passes through the flow path65and reaches the butterfly valve72when the rotation angle of the butterfly valve72is changed.

It is desirable that the change of the rotation speed of the flat screw40in step S14and the change of the opening area of the flow path65in step S16are executed so that the times required for the changes coincide with each other. InFIG.8, the time Tm1required for changing the rotation speed of the flat screw40and the time Tm2required for changing the angle of the butterfly valve72coincide with each other. Thus, when the angle of the butterfly valve72is changed, excess or deficiency of the plasticized material supplied to the butterfly valve72can be suppressed.

In step S18ofFIG.6, the control section300judges whether the pressure in the flow path65measured by the pressure sensor80exceeds a predetermined threshold. When it is determined that the pressure exceeds the predetermined threshold value, then in step S20, the control section300decreases the rotation speed of the flat screw40. Specifically, the control section300stops the rotation of the flat screw40until the pressure measured by the pressure sensor80falls below the threshold described above. In this way, “reducing the rotation speed” includes stopping the rotation. When it is judged in step S18that the pressure does not exceed the predetermined threshold, the control section300skips the process of step S20. Note that the control section300may make the judgement in step S18by using a mean value of one or more pressure measurement values measured in the past and the pressure measurement value measured this time. In this way, even in a case where a measurement error is included in the measurement value due to the influence of noise or the like, it is possible to appropriately determine whether or not to decrease the rotation speed of the flat screw40.

In step S22, the control section300judges whether or not the movement speed of the nozzle61should be decreased. For example, when the nozzle61is moved along a bent path, the control section300decreases the movement speed of the nozzle61. When it is judged that the movement speed of the nozzle61is to be decreased, then in step S24, the control section300sets the rotation speed of the butterfly valve72to the first adjustment speed and rotates the butterfly valve72at the first adjustment speed, thereby reducing the opening area of the flow path65from the second opening area to the first opening area and reducing the ejecting amount of the plasticized material. The process of step S24is also referred to as a first process. In step S22, when it is not judged that the movement speed of the nozzle61is to be decreased, the control section300skips the process of step S24.

In step S26, the control section300judges whether to increase the movement speed of the nozzle61. For example, the control section300increases the movement speed of the nozzle61when the nozzle61is moved along a linear path. When it is judged that the movement speed of the nozzle61is to be increased, then in step S28, the control section300sets the rotation speed of the butterfly valve72to the second adjustment speed, which is higher than the first adjustment speed, and rotates the butterfly valve72at the second adjustment speed, thereby increasing the opening area of the flow path65from the first opening area to the second opening area and increasing the ejecting amount of the plasticized material. The process of step S28is also referred to as a second process. In step S26, when it is not judged to increase the movement speed of the nozzle61, then the control section300skips the process of step S28. The judgement of whether or not to change the movement speed of the nozzle61in step S22and step S26described above may be executed based on, for example, a command or data for changing the movement speed included in the molding data.

In step S30, the control section300judges whether or not the molding of the three dimensional molded object is completed. When it is judged that the molding of the three dimensional molded object is completed, then the control section300terminates the three dimensional molding process. On the other hand, in a case where it is judged that the molding of the three dimensional molded object is not completed, then the control section300returns the process to step S10and continues the molding of the three dimensional molded object.

In the three dimensional molding device100according to the first embodiment described above, as shown inFIG.7, the rotation speed of the flat screw40is controlled at the first rotation speed when the opening area of the flow path65is the first opening area, and the rotation speed of the flat screw40is controlled at the second rotation speed, which is higher than the first rotation speed, when the opening area of the flow path65is the second opening area, which is larger than the first opening area. Therefore, when the ejecting amount of the plasticized material from the nozzle61is large, the rotation speed of the flat screw40can be increased to increase the generation amount of the plasticized material, and when the ejecting amount of the plasticized material from the nozzle61is small, the rotation speed of the flat screw40can be decreased to decrease the generation amount of the plasticized material. Therefore, for example, in the three dimensional molding device in which the rotation speed of the flat screw40is set to a constant speed, when the opening area of the flow path65is decreased, the pressure in the flow path65upstream of the ejection adjustment section70increases, and when the opening area of the flow path65is subsequently increased, there is a possibility that a phenomenon occurs in which an unexpected ejecting amount of plasticized material is ejected from the nozzle61, but such a phenomenon can be suppressed in the present embodiment. Therefore, the molded object can be molded with high accuracy.

In addition, in the present embodiment, since the ejection adjustment section70which adjusts the ejecting amount of the plasticized material from the nozzle61includes the butterfly valve72, and the control section300controls the rotation angle of the butterfly valve72based on the detection value of the angle detection sensor73, it is possible to adjust the opening area of the flow path65with a simple configuration.

Further, in the present embodiment, when the pressure, which was measured by the pressure sensor80detecting the pressure in the flow path65upstream of the butterfly valve72, exceeds a predetermined value, then the rotation speed of the flat screw40is decreased. Therefore, it is possible to prevent the pressure in the flow path65upstream of the butterfly valve72from increasing excessively, and it is possible to more reliably prevent the plasticized material of an unintended ejecting amount from being ejected from the nozzle61. In addition, by decreasing the rotation speed of the flat screw40, it is possible to suppress the resin from being modified in the plasticizing section30.

Further, in the present embodiment, the control section300starts the operation for changing the rotation speed of the flat screw40earlier than the operation for changing the opening area of the flow path65. Therefore, when the opening area of the flow path65is changed, it is possible to suppress the occurrence of insufficient supply of the plasticized material from the plasticizing section30to the ejection adjustment section70, and it is possible to suppress the occurrence of ejection defects.

In addition, in the present embodiment, in the adjustment of the opening area of the flow path65using the ejection adjustment section70, the control section300executes either a process of changing the opening area at a first adjustment speed and a process of changing the opening area at a second adjustment speed faster than the first adjustment speed. Therefore, the control section300can adjust the opening area of the flow path65in at least two stages of adjustment speeds.

In addition, in the present embodiment, in the adjustment of the opening area, the control section300can execute either the first process of changing from the second opening area to the first opening area at the first adjustment speed or the second process of changing from the first opening area to the second opening area at the second adjustment speed. Then, the control section300executes the first process in a case where the relative movement speed of the nozzle61is to be decreased and executes the second process in a case where the relative movement speed of the nozzle61is to be increased. In other words, according to the present embodiment, the opening area of the flow path65is decreased when the relative movement speed of the nozzle61is to be decreased and the opening area of the flow path65is increased when the relative movement speed of the nozzle61is to be increased. The adjustment speed of the opening area is made faster when the opening area of the flow path65is to be increased than when it is to be decreased. Therefore, when the movement speed of the nozzle61is to be increased, it is possible to rapidly increase the ejecting amount of the plasticized material, and it is possible to suppress a line width of the plasticized material from becoming thin in the linear section of the molded object.

B. Second Embodiment

FIG.9is a flowchart of the three dimensional molding process according to a second embodiment. In the second embodiment, the process in step S18bshown inFIG.9is different from the process in step S18in the first embodiment, and the other processing contents are the same as those in the first embodiment. The configuration of the three dimensional molding device100in the second embodiment is the same as that in the first embodiment. However, in the second embodiment, the three dimensional molding device100may not include the pressure sensor80.

As shown inFIG.9, in the second embodiment, after the process from step S10to step S16is finished, in step S18b, the control section300judges whether or not a state in which the opening area of the flow path65is equal to or less than a predetermined value has continued for a predetermined time or more. When it is judged that the state in which the opening area of the flow path65is equal to or less than the predetermined value has continued for the predetermined time or more, then in step S20the control section300decreases the rotation speed of the flat screw40to decrease the pressure in the flow path65upstream of the butterfly valve72.

According to the second embodiment described above, it is possible to suppress the pressure in the flow path65upstream of the butterfly valve72from excessively increasing without using the pressure sensor80. Therefore, similarly to the first embodiment, it is possible to more reliably suppress the plasticized material of an unintended ejecting amount from being ejected from the nozzle61. By executing experiments or simulations, the above described “predetermined value” and “predetermined time” can be set according to whether or not the pressure in the flow path65upstream of the butterfly valve72excessively increases when the value and the time are satisfied.

C. Other Embodiments

(C1) In the above embodiment, the ejection adjustment section70includes the butterfly valve72. In contrast, the ejection adjustment section70may include, for example, a shutter mechanism that adjusts the opening area of the flow path65by moving across the flow path65, or a pin-shaped opening and closing mechanism that is provided in the flow path65along the direction in which the flow path65extends and that adjusts the opening area of the flow path65in the vicinity of the nozzle opening62by moving toward the nozzle opening62.

(C2) In the above embodiment, if there is a certain response delay to the change in the angle of the butterfly valve72or the change in the rotation speed of the flat screw40, a command may be transmitted from the control section300to the first drive section74or the drive motor32at a timing in consideration of the response delay. That is, if the timing at which the angle of the butterfly valve72is changed or the timing at which the rotation speed of the flat screw40is changed actually corresponds to the timing shown inFIG.8, the command for changing the angle of the butterfly valve72may be transmitted prior to the command for changing the rotation speed of the flat screw40.

(C3) In the above embodiment, as shown inFIG.8, the control section300starts the operation for changing the rotation speed of the flat screw40earlier than the operation for changing the opening area of the flow path65. In contrast, the control section300may start the operation of changing the rotation speed of the flat screw40and the operation of changing the opening area of the flow path65at the same timing.

(C4) In the above described embodiment, the processes of step S18and step S20and the processes of step S22to step S28inFIG.6orFIG.9are optional, and the control section300may not execute at least a part of these processes.

(C5) In the above embodiment, the control section300can adjust the opening area of the flow path65at the adjustment speed in two stages, but the adjustment speed may be fixed, or may be adjustable in three stages or steplessly.

(C6) In the above embodiment, the plasticizing section30plasticizes the material by the flat screw40. In contrast, the plasticizing section30may plasticize the material by rotating an in-line screw, for example.

(C7) In the above embodiment, the control section300controls the rotation angle of the butterfly valve72based on the detection value of the angle detection sensor73. The control section300may control the rotation speed of the flat screw40based on the detection value of the angle detection sensor73. By using the angle detection sensor73, the opening area of the flow path65can be accurately detected based on the detection value of the rotation angle of the butterfly valve72. Therefore, the rotation speed of the flat screw40can be accurately controlled.

D. Other Forms

The present disclosure is not limited to the above described embodiments, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described below can be appropriately replaced or combined in order to solve a part or all of the problems described above or in order to achieve a part or all of the effects described above. In addition, unless the technical features are described as essential in the present specification, the technical features can be appropriately deleted.

(1) According to the first aspect of the present disclosure, the three dimensional molding device is provided.

This three dimensional molding device includes a plasticizing section that has a screw in which a groove is formed and that is configured to generate a plasticized material by plasticizing a material by rotating the screw; a nozzle that has a nozzle opening and that is configured to eject the plasticized material; a table on which the plasticized material ejected from the nozzle is deposited; a position changing section configured to change a relative position between the nozzle and the table; an ejection adjustment section that is provided in a flow path, which communicates with the nozzle opening and through which the plasticized material flows, and that is configured to adjust an ejecting amount of the plasticized material from the nozzle by adjusting an opening area of the flow path; and a control section configured to mold a three dimensional molded object in a molding area of the table by controlling the plasticizing section, the position changing section, and the ejection adjustment section, wherein the control section controls a rotation speed of the screw at a first rotation speed when the opening area of the flow path is a first opening area and controls the rotation speed of the screw at a second rotation speed that is faster than the first rotation speed when the opening area of the flow path is a second opening area that is larger than the first opening area.

According to such an aspect, when the ejecting amount of the plasticized material from the nozzle is large, the rotation speed of the screw can be increased to increase the generation amount of the plasticized material, and when the ejecting amount of the plasticized material from the nozzle is small, the rotation speed of the screw can be decreased to decrease the generation amount of the plasticized material. Therefore, it is possible to suppress ejection of an unexpected ejecting amount of plasticized material from the nozzle due to an increase in the pressure in the flow path on the upstream of the ejection adjustment section. Therefore, the molded object can be molded with high accuracy.

(2) The above aspect may be such that the ejection adjustment section includes a drive shaft disposed along a direction intersecting a direction in which the flow path extends, a valve formed in a portion of the drive shaft, a drive section that rotates the valve by rotating the drive shaft, and an angle detection sensor that detects a rotation angle of the valve, the control section is configured to adjust the opening area by controlling the rotation angle of the valve, and the control section is configured to control the rotation speed based on a detection value of the angle detection sensor.

With such a configuration, the rotation speed of the screw can be accurately controlled.

(3) The above aspect may be such that a pressure sensor configured to detect pressure in the flow path upstream of the ejection adjustment section, wherein the control section is configured to decrease the rotation speed of the screw when a pressure exceeding a predetermined value is detected.

According to such an aspect, it is possible to more reliably suppress ejection of an unintended ejecting amount of plasticized material from the nozzle due to an increase in the pressure upstream of the ejection adjustment section.

(4) The above aspect may be such that the control section is configured to decrease the rotation speed of the screw when the opening area remains at or below a predetermined value for a predetermined time or more.

According to such an aspect, it is possible to more reliably suppress ejection of an unintended ejecting amount of plasticized material from the nozzle due to an increase in the pressure upstream of the ejection adjustment section.

(5) The above aspect may be such that the control section is configured to start an operation for changing the rotation speed of the screw earlier than an operation for changing the opening area of the flow path.

According to such an aspect, it is possible to suppress the occurrence of insufficient supply of the plasticized material when the opening area of the flow path is changed.

(6) The above aspect may be such that the control section is configured to, in adjustment of the opening area, execute either a process of changing the opening area at a first adjustment speed or a process of changing the opening area at a second adjustment speed higher than the first adjustment speed.

According to such a configuration, the opening area of the flow path can be adjusted at the adjustment speed of at least two stages.

(7) The above aspect may be such that the control section is configured to, in adjustment of the opening area, execute either a first process of changing from the second opening area to the first opening area at the first adjustment speed or a second process of changing from the first opening area to the second opening area at the second adjustment speed, and is configured to execute the first process in a case where the relative movement speed of the nozzle is to be decreased and to execute the second process in a case where the relative movement speed of the nozzle is to be increased.

According to such an aspect, when the movement speed of the nozzle is to be increased, the ejecting amount of the plasticized material can be rapidly increased.

(8) According to the second aspect of the present disclosure, there is provided the method for manufacturing the three dimensional molded object. This manufacturing method includes a first step of plasticizing a material by rotating a screw, in which a groove is formed, to generate a plasticized material and a second step of molding a three dimensional molded object by discharging the plasticized material from a nozzle having a nozzle opening, wherein the second step includes a step of adjusting an ejecting amount of the plasticized material from the nozzle by adjusting an opening area of a flow path which communicates with the nozzle opening and through which the plasticized material flows and the first step includes a step of setting the rotation speed of the screw to a first rotation speed when the opening area of the flow path is a first opening area and setting the rotation speed of the screw to a second rotation speed that is higher than the first rotation speed when the opening area of the flow path is second opening area that is larger than the first opening area.

The present disclosure is not limited to the three dimensional molding device and the three dimensional molded object manufacturing method described above, and can be realized by various aspects such as a three dimensional molding system, a computer program, and a non-transitory tangible recording medium in which a computer program is recorded in a computer-readable manner.