Three-dimensional modeling device

Abstract

Provided is a technique capable of stabilizing the discharge amount at the time of restart of discharge or immediately after restart of discharge in a three-dimensional molding device. The three-dimensional modeling apparatus includes: a plasticization unit having a screw and generating a plasticized material; the nozzle is provided with a nozzle opening and is used for spraying the plasticized material; a discharge amount adjustment mechanism for controlling the discharge amount of the plasticizing material from the nozzle opening by adjusting the opening degree of a flow path communicating with the nozzle opening; and a control unit that performs at least one of: a first control in which the rotational speed of the screw is changed in multiple stages after the ejection of the plasticized material is stopped and during an ejection stop period, which is a period before the ejection of the plasticized material is re-started, and a second control in which the rotational speed of the screw is changed in multiple stages after the ejection of the plasticized material is stopped; and a second control in which the rotational speed of the screw is changed in multiple stages during a restart ejection period, which is a period in which the opening degree of the flow path reaches the opening degree specified by the ejection amount adjustment mechanism, after restart of ejection of the plasticized material, and in which the control unit decreases the rotational speed of the screw and then increases the rotational speed of the screw.

Description

Technical Field

[0001] The present disclosure relates to a three-dimensional modeling device. Background Art

[0002] Patent Document 1 discloses a three-dimensional modeling apparatus including a flow rate adjustment mechanism capable of controlling the amount of molten material ejected from a nozzle.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2019-81263

[0004] The three-dimensional modeling device disclosed in Patent Document 1 can adjust the spraying amount from the nozzle by adjusting the rotation angle of the butterfly valve as a flow regulating mechanism. However, during the period from when the spraying stops to when the spraying starts again, the pressure in the flow path upstream of the butterfly valve is sometimes unstable, and the spraying amount is unstable when or just after the spraying starts again. Summary of the invention

[0005] According to a first aspect of the present disclosure, a three-dimensional modeling device is provided. The three-dimensional modeling device comprises: a plasticizing unit having a screw and a motor for rotating the screw, so as to plasticize a material to generate a plasticized material; a nozzle having a nozzle opening, so as to eject the plasticized material; an ejection amount adjustment mechanism, which is provided in a flow path for the plasticized material to flow and is connected to the nozzle opening, and controls the ejection amount of the plasticized material from the nozzle opening by adjusting the opening of the flow path; and a control unit, which controls the plasticizing unit and the ejection amount adjustment mechanism, and the control unit performs at least one of the following controls: a first control, in which the ejection amount adjustment mechanism is configured to eject the plasticized material from the nozzle opening; After the ejection of the plasticized material from the nozzle opening stops, the rotation speed of the screw is changed in multiple stages during the ejection stop period which is a period before the ejection of the plasticized material from the nozzle opening is restarted; and a second control, after the ejection of the plasticized material from the nozzle opening is restarted, the rotation speed of the screw is changed in multiple stages during the ejection restart period which is a period until the opening of the flow path reaches the opening specified by the ejection amount adjustment mechanism, in which the control unit decreases the rotation speed of the screw and then increases it. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is an explanatory diagram showing the schematic structure of a three-dimensional modeling system.

[0007] Figure 2 It is a perspective view showing a schematic structure of a screw.

[0008] Figure 3 This is a schematic top view of the barrel.

[0009] Figure 4This is an explanatory diagram schematically showing a situation in which a three-dimensional modeling device models a modeled object.

[0010] Figure 5 It is an explanatory diagram showing a schematic configuration of an information processing device.

[0011] Figure 6 It is a flowchart of the modeling process.

[0012] Figure 7 It is a timing chart showing the processing contents of the first control.

[0013] Figure 8 This is the first diagram showing the time change of the internal pressure.

[0014] Fig. 9 This is a second graph showing the temporal change of the internal pressure.

[0015] Fig.10 This is a graph showing the relationship between the maximum internal pressure at each rotation speed and the time until the pressure reaches 80% of the maximum internal pressure.

[0016] Fig.11 This is a diagram showing changes in internal pressure when the rotation speed of the screw is changed stepwise.

[0017] Fig.12 Yes Fig.11 A graph with an extended timeline.

[0018] Fig.13 This is a detailed flowchart of the first control in the second embodiment.

[0019] Fig.14 yes Fig.13 A timing diagram of the process in step S55.

[0020] Fig.15 yes Fig.13 A timing diagram of the process in step S56.

[0021] Fig.16 This is a graph showing the target value of the internal pressure corresponding to the position of the plunger.

[0022] Fig.17 This is a flowchart of the modeling process in the fourth embodiment.

[0023] Fig.18 It is a timing chart showing the processing contents of the second control.

[0024] Description of Reference Numerals

[0025] 10…Three-dimensional molding system, 20…Material supply unit, 22…Communication path, 30…Plasticizing unit, 31…Screw housing, 32…Drive motor, 40…Screw, 42…Groove unit, 43…Ribbon unit, 44…Material inlet, 46…Central unit, 47…Upper surface, 48…Lower surface, 50…Barrel, 52…Upper surface, 54…Guide groove, 56…Communication hole, 58…Barrel heater, 60…Discharging unit, 61…Nozzle, 62…Nozzle opening, 65…Flow path, 66…Branch flow path, 67…Plunger, 70…Discharging amount adjustment mechanism, 74…First driving unit , 75…suction mechanism, 76…second drive unit, 77…ejection control unit, 100…three-dimensional modeling device, 110…head, 210…stage, 211…modeling surface, 212…stage heater, 230…moving mechanism, 300…control unit, 310…processor, 320…storage device, 400…information processing device, 410…CPU, 411…data generation unit, 420…memory, 430…storage device, 440…communication interface, 450…input-output interface, 460…bus, 470…input device, 480…display unit. DETAILED DESCRIPTION

[0026] A. First Implementation Method:

[0027] Figure 1 1 is an explanatory diagram showing a schematic configuration of a three-dimensional modeling system 10 in the first embodiment. Figure 1 The arrows indicating the mutually orthogonal X, Y, and Z directions are shown in the figure. The X direction and the Y direction are directions parallel to the horizontal plane, and the Z direction is a direction along the vertical upward direction. The arrows indicating the X, Y, and Z directions are also shown in the directions shown in the figure in other figures. Figure 1 The corresponding manner is appropriately illustrated. In the following description, when determining the direction, the direction indicated by the arrow in each figure is set to "+", and the opposite direction is set to "-", and positive and negative signs are used in the direction mark. In the following, the +Z direction is also referred to as "up", and the -Z direction is also referred to as "down".

[0028] The three-dimensional modeling system 10 includes a three-dimensional modeling device 100 and an information processing device 400. The three-dimensional modeling device 100 of this embodiment is a device for modeling a modeled object by extruding a material. The three-dimensional modeling device 100 includes a control unit 300 for controlling each unit of the three-dimensional modeling device 100. The control unit 300 and the information processing device 400 are connected in a manner that allows mutual communication.

[0029] The three-dimensional modeling device 100 includes: a head 110 for generating and ejecting a plasticized material; a stage 210 for modeling, which serves as a base for a modeled object; and a moving mechanism 230 for controlling the ejection position of the plasticized material.

[0030] The head 110 ejects the plasticized material obtained by plasticizing the solid material onto the stage 210 under the control of the control unit 300. The head 110 includes: a material supply unit 20, which is a supply source of the raw material before being converted into the plasticized material; a plasticizing unit 30, which converts the raw material into the plasticized material; and an ejection unit 60, which ejects the plasticized material.

[0031] The material supply unit 20 supplies the raw material MR to the plasticizing unit 30. The material supply unit 20 is composed of, for example, a hopper for storing the raw material MR. The material supply unit 20 is connected to the plasticizing unit 30 via a communication path 22. The raw material MR is fed into the material supply unit 20 in the form of powder or granules. As the raw material MR, for example, a resin material such as ABS (acrylonitrile-butadiene-styrene), PEEK (polyetheretherketone), or PP (polypropylene) is used.

[0032] The plasticizing section 30 plasticizes the raw material MR supplied from the material supply section 20 to generate a paste-like plasticized material showing fluidity, and guides it to the ejection section 60. In the present embodiment, "plasticization" is a concept including melting, which is a state of changing from a solid to a fluid state. Specifically, in the case of a material undergoing a glass transition, plasticization means setting the temperature of the material to a level above the glass transition point. In the case of a material not undergoing a glass transition, plasticization means setting the temperature of the material to a level above the melting point.

[0033] The plasticizing part 30 has a screw housing 31, a driving motor 32, a screw 40 and a barrel 50. The screw 40 is also called a flat screw, a rotor or a scroll. The barrel 50 is also called a screw counter part.

[0034] The screw 40 is accommodated in the screw housing 31. The upper surface 47 of the screw 40 is connected to the drive motor 32, and the screw 40 rotates in the screw housing 31 by the rotational driving force generated by the drive motor 32. The drive motor 32 is driven under the control of the control unit 300. In addition, the screw 40 can also be driven by the drive motor 32 via a speed reducer.

[0035] Figure 2 4 is a perspective view showing a schematic structure of the lower surface 48 side of the screw 40. In order to facilitate understanding of the technology, Figure 2 The screw 40 shown is used to Figure 1 The positional relationship between the upper surface 47 and the lower surface 48 shown is shown in a state in which the positional relationship is reversed in the vertical direction. The screw 40 has a substantially cylindrical shape in which the length along the direction of its central axis, i.e., the axial direction, is smaller than the length in the direction perpendicular to the axial direction. The screw 40 is arranged in such a manner that the rotation axis RX, which is the rotation center thereof, is parallel to the Z direction.

[0036] A spiral groove 42 is formed on the surface of the screw 40 that intersects the rotation axis RX, that is, the lower surface 48. The communication path 22 of the material supply part 20 is connected to the groove 42 from the side of the screw 40. In the present embodiment, the groove 42 is separated by the convex strips 43 to form three grooves. In addition, the number of grooves 42 is not limited to three, and can be one, or more than two. The groove 42 is not limited to a spiral shape, and can be a spiral or involute curve shape, or a shape extending from the central part toward the periphery in an arc shape.

[0037] like Figure 1 As shown, the lower surface 48 of the screw 40 is opposite to the upper surface 52 of the barrel 50, and a space is formed between the groove 42 of the lower surface 48 of the screw 40 and the upper surface 52 of the barrel 50. Figure 2 The material inlet 44 shown supplies the raw material MR to the space between the screw 40 and the barrel 50 .

[0038] A barrel heater 58 for heating the raw material MR supplied into the groove portion 42 of the rotating screw 40 is embedded in the barrel 50. A communication hole 56 is provided at the center of the barrel 50.

[0039] Figure 3 1 is a schematic top view showing the upper surface 52 side of the barrel 50. A plurality of guide grooves 54 connected to the communicating hole 56 and extending in a spiral shape from the communicating hole 56 toward the outer periphery are formed on the upper surface 52 of the barrel 50. In addition, one end of the guide groove 54 may not be connected to the communicating hole 56. In addition, the guide groove 54 may also be omitted.

[0040] The raw material MR supplied to the groove portion 42 of the screw 40 is plasticized in the groove portion 42 while flowing along the groove portion 42 by the rotation of the screw 40, and is guided to the central portion 46 of the screw 40 as a plasticized material. The plasticized material in a paste state showing fluidity that flows into the central portion 46 is supplied to the ejection portion 60 via the connecting hole 56 provided in the center of the barrel 50. In addition, in the plasticized material, all kinds of substances constituting the plasticized material may not be plasticized. The plasticized material can be converted into a state having fluidity as a whole by plasticizing at least a part of the substances constituting the plasticized material.

[0041] Figure 1 The ejection unit 60 includes a nozzle 61 for ejecting a plasticized material, a flow path 65 for the plasticized material provided between the screw 40 and the nozzle opening 62, and an ejection control unit 77 for controlling the ejection of the plasticized material.

[0042] The nozzle 61 is connected to the communication hole 56 of the barrel 50 via a flow path 65. The nozzle 61 ejects the plasticized material generated in the plasticizing section 30 toward the stage 210 from a nozzle opening 62 at the front end.

[0043] The discharge control unit 77 includes a discharge amount adjustment mechanism 70 for opening and closing the flow path 65 and a suction mechanism 75 for sucking and temporarily storing the plasticized material.

[0044] The ejection amount adjustment mechanism 70 is provided in the flow path 65, and changes the opening of the flow path 65 by rotating in the flow path 65. In the present embodiment, the ejection amount adjustment mechanism 70 is composed of a valve. The ejection amount adjustment mechanism 70 is driven by a first drive unit 74 under the control of the control unit 300. The first drive unit 74 is composed of, for example, a stepping motor. The control unit 300 can adjust the flow rate of the plasticized material flowing from the plasticizing unit 30 to the nozzle 61, that is, the ejection amount of the plasticized material ejected from the nozzle 61, by controlling the rotation angle of the valve using the first drive unit 74. The ejection amount adjustment mechanism 70 can adjust the ejection amount of the plasticized material, and can control the on / off of the outflow of the plasticized material.

[0045] The suction mechanism 75 includes a branch flow path 66 connected to the flow path 65 and a plunger 67 disposed in the branch flow path 66. The branch flow path 66 is connected to the flow path 65 between the ejection amount adjustment mechanism 70 and the nozzle opening 62. Hereinafter, the plunger 67 in the branch flow path 66 moving away from the flow path 65 is referred to as "pulling the plunger 67", and the plunger 67 moving close to the flow path 65 is referred to as "pressing the plunger 67". The plunger 67 of the suction mechanism 75 is driven by the second drive unit 76 under the control of the control unit 300. The second drive unit 76 is composed of, for example, a stepping motor, a gear rack mechanism that converts the rotational force of the stepping motor into the translational motion of the plunger 67, and the like.

[0046] The control unit 300 controls the suction mechanism 75 to temporarily suck the plasticized material in the flow path 65 into the branch flow path 66 by pulling the plunger 67 when the ejection of the plasticized material from the nozzle 61 stops. In this way, it is possible to suppress the tailing phenomenon in which the plasticized material hangs down like a line drawn from the nozzle opening 62. In addition, when the plasticized material from the nozzle 61 starts to be ejected again, the control unit 300 pulls the plunger 67 to suck the plasticized material in the flow path 65, or presses the plunger 67 to send the plasticized material into the flow path 65, thereby adjusting the ejection amount of the plasticized material sent from the nozzle 61 to be constant. In this way, when the ejection starts again, the line width of the plasticized material can be kept constant.

[0047] The stage 210 is arranged at a position opposite to the nozzle opening 62 of the nozzle 61. In the first embodiment, the molding surface 211 of the stage 210 opposite to the nozzle opening 62 of the nozzle 61 is arranged in parallel with the X and Y directions, that is, the horizontal direction. The stage 210 is provided with a stage heater 212 for suppressing rapid cooling of the plasticized material ejected onto the stage 210. The stage heater 212 is controlled by the control unit 300.

[0048] The moving mechanism 230 changes the relative position between the stage 210 and the nozzle 61 under the control of the control unit 300. In the present embodiment, the position of the nozzle 61 is fixed, and the moving mechanism 230 moves the stage 210. The moving mechanism 230 is composed of a three-axis positioner that moves the stage 210 in the three axial directions of X, Y, and Z by the driving force of three motors. In this specification, unless otherwise specified, the movement of the nozzle 61 means that the nozzle 61 and the ejection unit 60 are moved relative to the stage 210.

[0049] In addition, in other embodiments, instead of the structure in which the stage 210 is moved by the moving mechanism 230, a structure in which the moving mechanism 230 moves the nozzle 61 relative to the stage 210 while the position of the stage 210 is fixed may be adopted. In addition, the following structure may be adopted: the stage 210 is moved in the Z direction by the moving mechanism 230 to move the nozzle 61 in the X and Y directions; the stage 210 is moved in the X and Y directions by the moving mechanism 230 to move the nozzle 61 in the Z direction. Even in these structures, the relative positional relationship between the nozzle 61 and the stage 210 can be changed.

[0050] exist Figure 1 Although only one head 110 is shown in the figure, the three-dimensional modeling device 100 may also include a plurality of heads 110. By including a plurality of heads 110, different types of plasticized materials can be ejected from each head 110. Therefore, for example, different types of plasticized materials can be used to model the main body of the modeled object and the supporting structure that supports the modeled object.

[0051] The control unit 300 is a control device for controlling the overall operation of the three-dimensional modeling device 100. The control unit 300 is composed of a computer, which includes one or more processors 310, a storage device 320 composed of a main storage device and an auxiliary storage device, and an input / output interface for inputting and outputting signals with the outside. The processor 310 controls the plasticizing unit 30 and the moving mechanism 230 according to the modeling data obtained from the information processing device 400 by executing the program stored in the storage device 320, and models the modeling object on the stage 210. In addition, the control unit 300 can also be implemented by a structure combining circuits instead of being composed of a computer.

[0052] Figure 43D modeling apparatus 100 is an explanatory diagram schematically showing a situation in which a modeling object is modeled by a three-dimensional modeling apparatus 100. In the three-dimensional modeling apparatus 100, as described above, a raw material MR in a solid state is plasticized to generate a plasticized material MM. The control unit 300 sprays the plasticized material MM from the nozzle 61 while changing the position of the nozzle 61 relative to the stage 210 in the direction along the modeling surface 211 of the stage 210 while maintaining the distance between the modeling surface 211 of the stage 210 and the nozzle 61. The plasticized material MM sprayed from the nozzle 61 is continuously accumulated in the moving direction of the nozzle 61.

[0053] The control unit 300 repeatedly moves the nozzle 61 to form a layer ML. After forming one layer ML, the control unit 300 moves the nozzle 61 relative to the stage 210 in the Z direction, which is the stacking direction. Then, a further layer ML is stacked on the layer ML formed so far to form a molded object.

[0054] The control unit 300 may temporarily interrupt the ejection of the plasticized material from the nozzle 61, for example, when the nozzle 61 moves in the Z direction when one layer ML is completed, or when there are multiple independent molding areas in each layer. In this case, the control unit 300, for example, closes the flow path 65 through the ejection amount adjustment mechanism 70 to stop the ejection of the plasticized material MM from the nozzle opening 62, and temporarily sucks the plasticized material in the nozzle 61 through the suction mechanism 75. In addition, after changing the position of the nozzle 61, for example, the control unit 300 opens the flow path 65 through the ejection amount adjustment mechanism 70 while discharging the plasticized material in the suction mechanism 75, thereby restarting the accumulation of the plasticized material MM from the changed position of the nozzle 61.

[0055] Figure 5 4 is an explanatory diagram showing a schematic structure of an information processing device 400. The information processing device 400 is configured as a computer in which a CPU 410, a memory 420, a storage device 430, a communication interface 440, and an input / output interface 450 are mutually connected via a bus 460. An input device 470 such as a keyboard and a mouse, and a display unit 480 such as a liquid crystal display are connected to the input / output interface 450. The information processing device 400 is connected to the control unit 300 of the three-dimensional modeling device 100 via the communication interface 440.

[0056] The CPU 410 functions as a data generating unit 411 by executing a program stored in the storage device 430 .

[0057] The data generation unit 411 generates modeling data. Modeling data is data representing information related to the moving path of the nozzle 61 relative to the stage 210, the amount of plasticized material ejected from the nozzle 61, the rotation speed of the screw 40, and the like. The data generation unit 411 reads in shape data representing the shape of a three-dimensional modeled object produced using three-dimensional CAD software or three-dimensional CG software, and divides the shape of the three-dimensional modeled object into layers of a specified thickness. As shape data, data in STL format, AMF format, and the like are used. The data generation unit 411 determines the moving path of the nozzle 61 and the amount of plasticized material in a manner that the divided layers are filled with plasticized material, thereby generating modeling data. Modeling data is represented by G code, M code, and the like.

[0058] Figure 6 4 is a flowchart of the modeling process executed by the control unit 300 of the three-dimensional modeling apparatus 100. In step S10, the control unit 300 acquires modeling data generated by the information processing apparatus 400.

[0059] In step S20, the control unit 300 performs molding control. In this molding control, the control unit 300 controls the plasticizing unit 30 to start ejecting the plasticized material, thereby molding a three-dimensional object. The control unit 300 controls the plasticizing unit 30, the ejection control unit 77, and the moving mechanism 230 according to the molding data, thereby Figure 4 As described in , a three-dimensional object is modeled on the stage 210.

[0060] In step S30, the control unit 300 determines whether to stop the ejection of the plasticized material from the nozzle opening 62. In step S30, the control unit 300 analyzes the modeling data, and determines to stop the ejection of the plasticized material if any of the following (A) to (D) is met. If it is determined that the ejection is not stopped, the control unit 300 returns the process to step S20 and continues the modeling of the three-dimensional modeling object until it is determined that the ejection is stopped.

[0061] (A) Complete modeling of all layers.

[0062] (B) In order to shape different layers, the nozzle 61 is moved in the Z direction.

[0063] (C) The nozzle 61 is moved to a different position in the same layer.

[0064] (D) When the three-dimensional modeling apparatus 100 includes a plurality of heads 110 , the head 110 to be used is switched.

[0065] If it is determined in step S30 that the ejection is stopped, the control unit 300 determines in step S40 whether the formation of all layers is completed. If it is determined that the formation of all layers is completed, the control unit 300 ends the formation process.

[0066] In step S40, if it is not determined that the molding of all layers is completed, the control unit 300 performs the first control in step S50. The first control is a control that changes the rotation speed of the screw 40 in multiple stages during the period before the ejection of the plasticized material from the nozzle opening 62 is restarted, i.e., during the ejection stop period, after the ejection of the plasticized material from the nozzle opening 62 is stopped. The so-called "changing the rotation speed of the screw 40 in multiple stages during the ejection stop period" means that the rotation speed of the screw 40 is changed once or more during the ejection stop period.

[0067] Figure 7 It is a timing chart showing the processing contents of the first control in the first embodiment. Figure 7 , a timing diagram of a signal indicating a target speed of the screw 40 output from the control unit 300 to the plasticizing unit 30 is shown. In the first control, the control unit 300 increases the speed of the screw 40 to a second speed which is a speed higher than the first speed in the period before the ejection stop period, and then decreases the speed of the screw 40 to a third speed which is lower than the first speed. The first speed is the speed of the screw 40 in the molding of the three-dimensional molded object. The second speed, the third speed, and the duration of the second speed are predetermined by simulation or experiment so that the pressure in the flow path 65 on the upstream side of the ejection amount adjustment mechanism 70 becomes an appropriate pressure when the ejection is started again. Hereinafter, the pressure in the flow path 65 on the upstream side of the ejection amount adjustment mechanism 70 is referred to as "internal pressure". The first speed, the second speed, the third speed, and the duration of each speed can also be changed according to the type of material used. In addition, the first speed and the second speed can also be the same speed.

[0068] After executing the first control, Figure 6 In step S60, the control unit 300 controls the ejection amount adjustment mechanism 70 to restart the ejection of the plasticized material from the nozzle opening 62. Figure 7 As shown, the control unit 300 increases the rotation speed of the screw 40 from the second rotation speed and returns to the first rotation speed in the period before the ejection stop period. Thereafter, the control unit 300 returns the process to step S20 to continue the molding of the three-dimensional object.

[0069] The three-dimensional modeling device 100 of the first embodiment described above performs the following first control: after stopping the ejection of the plasticized material, the rotation speed of the screw 40 is changed in multiple stages during the period before the ejection of the plasticized material from the nozzle opening 62 is restarted, that is, during the ejection stop period. Therefore, when the ejection is restarted, the internal pressure, which is the pressure in the flow path on the upstream side of the ejection amount adjustment mechanism 70, can be quickly stabilized to an appropriate pressure. As a result, the ejection amount when the ejection is restarted can be stabilized, and the line width can be kept constant.

[0070] Below, refer to Figure 8 to Figure 12 , the experimental results related to the first control are described. In this experiment, ABS resin is used as the material.

[0071] Figure 8 This is a diagram showing the time change of the internal pressure when the rotation speed of the screw 40 is 6 rpm. Fig. 9 Graphs showing the time variation of the internal pressure when the rotation speed of the screw 40 is 0.5 rpm. The horizontal axis in these graphs represents the time elapsed from the stop of the ejection. The vertical axis represents the internal pressure of the flow path 65 upstream of the ejection amount adjustment mechanism 70. Figure 8 At the speed shown, the internal pressure after the ejection stops becomes too high relative to the internal pressure when the ejection stops. When the ejection starts again, the ejection amount of the plasticized material increases significantly, making it difficult to keep the line width constant. Fig. 9 At the rotation speed shown, although the internal pressure can be suppressed from becoming too large, it takes time before the change of the internal pressure stabilizes. Therefore, when the ejection stop period is short, when the ejection is restarted, the internal pressure is insufficient and the ejection amount of the plasticized material may be insufficient.

[0072] Fig.10 This is a graph showing the relationship between the maximum internal pressure Pmax at each rotation speed and the time until the pressure reaches 80% of the maximum internal pressure Pmax. The maximum internal pressure Pmax refers to the internal pressure at the time when the pressure change becomes substantially zero due to the passage of time from the stop of the ejection. Fig.10 The experimental results shown in the figure show that in order to shorten the time until the internal pressure reaches the maximum internal pressure Pmax, even when the rotation speed is set to 1 to 2 rpm, it can be confirmed that the maximum internal pressure Pmax exceeds the appropriate pressure. The appropriate pressure is, for example, 2 to 3 times the internal pressure during molding, and is the pressure that can keep the line width constant by moving the plunger 67 when the ejection starts again. Figures 8 to 10 The experimental results shown in this article confirm that it is difficult to reduce the time until the internal pressure stabilizes and prevent the internal pressure from becoming excessively high when the rotation speed of the screw 40 is controlled to be constant without changing it during the ejection stop period.

[0073] Fig.11 This is a diagram showing changes in the internal pressure when the rotation speed of the screw 40 is reduced from 6 rpm to 0.5 rpm at the time point 0.3 seconds after the discharge is stopped. Fig.12 Yes Fig.11 The time axis of the graph is extended. Fig.11 , 12As shown in the figure, after the ejection stops, when the rotation speed of the screw 40 is changed in multiple stages, the internal pressure can be immediately increased to the appropriate pressure range shown by the dotted line, and the pressure can be stabilized in a short period of time. That is, it can be confirmed that the internal pressure can be suppressed from becoming excessive by the first control performed by the control unit 300, and the time until the internal pressure stabilizes can be shortened. Therefore, according to the first embodiment, the ejection amount when the ejection is restarted can be stabilized regardless of the length of the ejection stop period.

[0074] B. Second Implementation Method:

[0075] The configuration of the three-dimensional modeling system 10 in the second embodiment is the same as that in the first embodiment. In the second embodiment, the content of the first control executed by the control unit 300 in the modeling process is different from that in the first embodiment.

[0076] Fig.13 This is a detailed flowchart of the first control executed by the control unit 300 in the second embodiment. In step S51, the control unit 300 determines whether the reason for stopping the ejection is the above-mentioned (B), that is, moving the nozzle 61 in the Z direction.

[0077] In step S51, when it is determined that the ejection stop is the above-mentioned (B), the control unit 300 increases the rotation speed of the screw 40 to a second rotation speed higher than the first rotation speed that is the rotation speed before the ejection stop period in step S52, and then decreases the rotation speed of the screw 40 to a third rotation speed lower than the first rotation speed, thereby terminating the first control. The control content in step S52 is the same as that in step S53. Figure 7 The control contents are the same as the first control in the first embodiment shown.

[0078] When it is determined in step S51 that the reason for stopping discharge is not (B), the control unit 300 determines in step S53 whether the reason for stopping discharge is (C), that is, moves the nozzle 61 to a different position in the same layer.

[0079] In step S53, when it is determined that the reason for stopping the ejection is the above (C), the control unit 300 determines in step S54 whether the moving distance of the nozzle 61 in the same layer is shorter than a predetermined distance. When it is determined that the moving distance of the nozzle 61 is shorter than the predetermined distance, the control unit 300 executes the processing of step S55. The predetermined distance is, for example, 1 to 10 mm.

[0080] Fig.14This is a timing diagram in the processing of step S55. In step S55, the control unit 300 increases the rotation speed of the screw 40 to a second rotation speed which is higher than the first rotation speed which is the rotation speed before the ejection stop period, and then returns the rotation speed of the screw 40 to the first rotation speed, thereby ending the first control. Thus, even if the moving distance of the nozzle 61 in the same layer is short and the ejection stop period is short, the internal pressure can be quickly increased to an appropriate pressure. In addition, the control unit 300 may perform the step of returning the rotation speed from the second rotation speed to the first rotation speed not in the first control but just after the ejection is restarted after the first control ends.

[0081] exist Fig.13 When it is determined in step S54 that the moving distance of the nozzle 61 is longer than the predetermined distance, the control unit 300 executes the process of step S56.

[0082] Fig.15 This is a timing diagram in the processing of step S56. In step S56, the control unit 300 increases the speed of the screw 40 to a second speed that is higher than the first speed that is the speed before the ejection stop period, and then gradually decreases the speed of the screw 40 to a third speed that is lower than the first speed, thereby ending the first control. As a result, the internal pressure can be brought close to the target internal pressure in a short time, and the time until the internal pressure stabilizes can be shortened. In addition, if Fig.15 As shown, "gradually decreasing" includes decreasing the rotation speed in multiple stages and decreasing the rotation speed smoothly or linearly.

[0083] In the above step S53, when it is determined that the reason for stopping the ejection is not the above (B) or (C), that is, when it is determined that the reason for stopping the ejection is neither the movement of the nozzle 61 in the Z direction nor the movement of the nozzle 61 to a different position in the same layer, the control unit 300 stops the screw 40 in step S57, and after a certain period of time, returns the rotation speed of the screw 40 to the first rotation speed that is the rotation speed before the ejection stop period. The so-called reason for stopping the ejection is neither the movement of the nozzle 61 in the Z direction nor the movement of the nozzle 61 to a different position in the same layer, for example, when the head 110 to be used is switched or emergency maintenance is performed on the head 110 during the molding process. In addition, the control unit 300 may reduce the rotation speed without stopping the screw 40 in step S57. In addition, the timing for returning the rotation speed of the screw 40 to the first rotation speed may also be before or when the ejection is started again.

[0084] According to the second embodiment described above, the rotation speed of the screw 40 during the ejection stop period is switched according to the reason for ejection stop. Therefore, even if the ejection stop period is longer or shorter according to the reason for ejection stop, the internal pressure can be appropriately controlled.

[0085] In addition, in the second embodiment, the control unit 300 switches the control content according to the reason for stopping the ejection. In contrast, the control unit 300 may also calculate the length of the ejection stop period and switch the control content according to the length. For example, the control unit 300 may also perform the processing of step S57 when the ejection stop period is more than 5 minutes, perform the processing of step S52 when the ejection stop period is 10 to 20 seconds, perform the processing of step S56 when the ejection stop period is 1 to 10 seconds, and perform the processing of step S55 when the ejection stop period is less than 1 second.

[0086] In addition, in the second embodiment, if Fig.13 As shown, in the first control, the control unit 300 switches the control content to any one of the four according to the reason for stopping the ejection. In contrast, the control unit 300 may perform any of the processes of step S55, step S56, and step S57 in the first control regardless of the reason for stopping the ejection.

[0087] C. Third Implementation Method:

[0088] The configuration of the three-dimensional modeling system 10 in the third embodiment is the same as that in the first embodiment. In the third embodiment, the content of the first control executed by the control unit 300 in the modeling process is different from that in the first embodiment.

[0089] In the first control of the third embodiment, as Figure 7 As shown, the control unit 300 changes the rotation speed of the screw 40 in multiple stages, and controls the second rotation speed as described below according to the position of the plunger 67 when the ejection is stopped.

[0090] Fig.16 is a graph showing target values ​​of internal pressure corresponding to the position of the plunger 67. The control unit 300 controls the rotation speed of the screw 40 in such a manner that the further away the position of the plunger 67 is from the flow path 65 when the ejection is stopped, the smaller the internal pressure during the ejection stop period. In other words, the rotation speed of the screw 40 is controlled in such a manner that the closer the position of the plunger 67 is to the flow path 65, the larger the internal pressure. In further other words, the rotation speed of the screw 40 is controlled in such a manner that the internal pressure at a first position of the plunger 67 is higher than the internal pressure at a second position farther from the flow path 65 than the first position. An example of the relationship between the rotation speed of the screw 40 and the internal pressure is as follows: Fig.10 shown.

[0091] As described above, in order to make the ejection amount constant when or just after the ejection is restarted, the position of the plunger 67 is dynamically changed by the control unit 300. Therefore, the position of the plunger 67 when the ejection stops is not determined to be constant, and can be various positions. For example, when the plunger 67 is far away from the flow path 65, it is difficult to further pull the plunger 67, so when the internal pressure increases, it is difficult to absorb the pressure when the ejection starts again. On the contrary, when the plunger 67 is close to the flow path 65, it is difficult to further press the plunger 67, so when the internal pressure decreases, it is difficult to compensate for the pressure when the ejection starts again. In the third embodiment described above, the rotation speed of the screw 40 during the ejection stop period is controlled according to the position of the plunger 67. More specifically, the rotation speed of the screw 40 is controlled in such a way that the farther the position of the plunger 67 is from the flow path 65 when the ejection stops, the smaller the internal pressure. Therefore, according to the third embodiment, it is possible to suppress the internal pressure that hinders the movement of the plunger 67 when the ejection starts again, and it is easy to keep the ejection amount constant when the ejection starts again.

[0092] D. Fourth Implementation Method:

[0093] The configuration of the three-dimensional modeling system 10 in the fourth embodiment is the same as that in the first embodiment. In the fourth embodiment, a part of the modeling process executed by the control unit 300 is different from that in the first embodiment.

[0094] Fig.17 4 is a flowchart of the shaping process performed by the control unit 300 in the fourth embodiment. In the fourth embodiment, the first control is not performed, and after the ejection is restarted in step S60, the second control is performed in step S70. The other processing contents are the same as those in the first embodiment, so the description other than the contents of the second control is omitted below.

[0095] The second control is a control for changing the rotation speed of the screw 40 in multiple stages from the time when the opening of the flow path 65 reaches the opening designated by the discharge amount adjustment mechanism 70 after the discharge of the plasticized material from the nozzle opening 62 is resumed, i.e., during the discharge resumption period.

[0096] Fig.18 is a timing chart showing the processing contents of the second control in the fourth embodiment. Fig.18, a signal indicating the target rotation speed of the screw 40 output from the control unit 300 to the plasticizing unit 30, a signal indicating the target opening of the flow path 65 output from the control unit 300 to the ejection amount adjustment mechanism 70, and a timing chart of the actual opening of the flow path 65 are shown. In the fourth embodiment, in the second control, the control unit 300 reduces the rotation speed of the screw 40 during the restart of ejection and then increases it. More specifically, during the restart of ejection, the control unit 300 reduces the rotation speed of the screw 40 to a speed lower than the rotation speed during the ejection stop period, and then increases the rotation speed of the screw 40 to the normal rotation speed during molding.

[0097] According to the fourth embodiment described above, after the ejection of the plasticized material from the nozzle opening 62 is restarted, the rotation speed of the screw 40 is decreased and then increased during the period until the opening of the flow path 65 reaches the opening specified by the ejection amount adjustment mechanism 70, that is, during the ejection restart period. Therefore, even if the internal pressure becomes too high during the ejection stop period, by decreasing the rotation speed of the screw 40 during the ejection restart period, it is possible to suppress the ejection amount from increasing just after the ejection restarts. Therefore, the ejection amount just after the ejection restarts can be stabilized, and the line width can be easily made constant.

[0098] E. Other implementation methods:

[0099] (E1) In the first to third embodiments described above, the control unit 300 executes the first control in the shaping process, and executes the second control in the fourth embodiment. On the other hand, the control unit 300 may execute both the first control and the second control.

[0100] (E2) The control unit 300 may repeatedly increase and decrease the rotation speed of the screw 40 a plurality of times in the first control of each of the above embodiments. The control unit 300 may change the number of times the increase and decrease of the rotation speed are repeated according to the length of the ejection stop period.

[0101] (E3) In each of the above embodiments, the plasticizing section 30 may plasticize the material by rotating an inner screw.

[0102] F. Other methods:

[0103] The present disclosure is not limited to the above-mentioned embodiments, and can be implemented in various structures without departing from the scope of its main purpose. For example, the technical features of the embodiments corresponding to the technical features in each of the following modes can be appropriately replaced or combined in order to solve part or all of the above-mentioned problems, or to achieve part or all of the above-mentioned effects. In addition, if the technical feature is not described as a necessary feature in this specification, it can be appropriately deleted.

[0104] (1) According to a first aspect of the present disclosure, a three-dimensional modeling device is provided. The three-dimensional modeling device comprises: a plasticizing unit having a screw and a motor for rotating the screw, so as to plasticize a material to generate a plasticized material; a nozzle having a nozzle opening, so as to eject the plasticized material; an ejection amount adjustment mechanism, which is provided in a flow path for the plasticized material to flow and is connected to the nozzle opening, and controls the ejection amount of the plasticized material from the nozzle opening by adjusting the opening of the flow path; and a control unit, which controls the plasticizing unit and the ejection amount adjustment mechanism, and the control unit performs at least one of the following controls: a first control, in which the ejection amount adjustment mechanism is adjusted to control the ejection amount of the plasticized material from the nozzle opening; After the ejection of the plasticized material from the nozzle opening stops, the rotation speed of the screw is changed in multiple stages until the ejection of the plasticized material from the nozzle opening is restarted, i.e., during the ejection stop period; and a second control, after the ejection of the plasticized material from the nozzle opening is restarted, the rotation speed of the screw is changed in multiple stages until the opening of the flow path reaches the opening specified by the ejection amount adjustment mechanism, i.e., during the ejection restart period, in which the control unit decreases the rotation speed of the screw and then increases it.

[0105] According to such an aspect, by changing the rotation speed of the screw in multiple stages during the ejection stop period or the ejection restart period, the ejection amount of the plasticized material can be stabilized when or immediately after the ejection restarts.

[0106] (2) In the above-mentioned aspect, in the first control, the control unit may increase the rotation speed of the screw to a second rotation speed which is higher than the first rotation speed in the period before the ejection stop period, and then decrease the rotation speed of the screw to a third rotation speed which is lower than the first rotation speed. According to such an aspect, when the ejection is restarted, the ejection amount of the plasticized material can be stabilized.

[0107] (3) In the above aspect, in the first control, the control unit may gradually reduce the speed of the screw when reducing the speed of the screw from the second speed to the third speed. According to such an aspect, during the ejection stop period, the time until the pressure in the flow path upstream of the ejection amount adjustment mechanism becomes stable can be shortened.

[0108] (4) In the above aspect, in the first control, the control unit may increase the rotation speed of the screw to a second rotation speed which is higher than the first rotation speed in the period before the ejection stop period, and then return the rotation speed of the screw to the first rotation speed. According to such an aspect, even when the ejection stop period is short, the pressure in the flow path upstream of the ejection amount adjustment mechanism can be quickly increased to an appropriate pressure.

[0109] (5) In the above-mentioned mode, the three-dimensional modeling device may include a suction mechanism, the suction mechanism having a branch flow path connected to the flow path and a plunger disposed in the branch flow path, and by changing the position of the plunger, the plasticized material in the flow path can be sucked into the branch flow path, and in the first control, the control unit controls the rotation speed of the screw according to the position of the plunger in the branch flow path. According to such a mode, the pressure in the flow path on the upstream side of the ejection amount adjustment mechanism can be suppressed from becoming a pressure that hinders the action of the plunger when ejection is restarted.

[0110] The present disclosure is not limited to the above-mentioned three-dimensional modeling device, and can be implemented in various forms such as a three-dimensional modeling system, a method for manufacturing a three-dimensional modeled object, a computer program, and a non-transitory tangible recording medium that records the computer program in a computer-readable manner.

Claims

1. A three-dimensional modeling device, characterized in that: have: A plasticizing part, comprising a screw and a motor for rotating the screw, plasticizing the material to generate a plasticized material; a nozzle having a nozzle opening for spraying the plasticized material; A discharge amount adjustment mechanism is provided in a flow path for the plasticized material to flow and communicated with the nozzle opening, and controls the discharge amount of the plasticized material from the nozzle opening by adjusting the opening of the flow path; as well as a control unit, which controls the plasticizing unit and the ejection amount adjustment mechanism, The control unit performs at least one of the following controls: A first control of changing the rotation speed of the screw in multiple stages during a discharge stop period, which is a period before the discharge of the plasticized material from the nozzle opening is restarted, after the discharge of the plasticized material from the nozzle opening is stopped; as well as The second control is to change the rotation speed of the screw in multiple stages during a re-starting ejection period, which is a period until the opening of the flow path reaches the opening specified by the ejection amount adjustment mechanism, after the ejection of the plasticized material from the nozzle opening is restarted. In the second control, the control unit decreases the rotation speed of the screw and then increases it.

2. The three-dimensional modeling device according to claim 1, characterized in that: In the first control, the control unit increases the screw rotation speed to a second rotation speed higher than a first rotation speed in a period before the ejection stop period, and then decreases the screw rotation speed to a third rotation speed lower than the first rotation speed.

3. The three-dimensional modeling device according to claim 2, characterized in that: In the first control, the control unit gradually reduces the rotation speed of the screw when reducing the rotation speed of the screw from the second rotation speed to the third rotation speed.

4. The three-dimensional modeling device according to claim 1, characterized in that: In the first control, the control unit increases the rotation speed of the screw to a second rotation speed that is higher than the first rotation speed in a period before the ejection stop period, and then returns the rotation speed of the screw to the first rotation speed.

5. The three-dimensional modeling device according to claim 1, characterized in that: The three-dimensional modeling device includes a suction mechanism, which has a branch flow path connected to the flow path and a plunger arranged in the branch flow path, and can suck the plasticized material in the flow path into the branch flow path by changing the position of the plunger. In the first control, the control unit controls the rotation speed of the screw according to the position of the plunger in the branch flow channel.

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