Patent Publication Number: US-2022234280-A1

Title: Three-Dimensional Shaping Device and Method for Manufacturing Three-Dimensional Shaped Object

Description:
This application is a divisional of U.S. patent application Ser. No. 16/912,260 filed Jun. 25, 2020, which is based on, and claims priority from JP Application Serial Number 2019-120736, filed Jun. 28, 2019, the disclosures of which are hereby incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a three-dimensional shaping device and a method for manufacturing a three-dimensional shaped object. 
     2. Related Art 
     For example, WO 2015/129733 discloses a three-dimensional shaping device including a cylinder having a nozzle for discharging molten resin, a screw disposed inside the cylinder, and a pressure gauge measuring pressure of the molten resin in a vicinity of the nozzle. In this three-dimensional shaping device, a motor that rotates the screw is controlled based on a pressure value measured by the pressure gauge so that the molten resin is stably discharged from the nozzle. 
     In order to shape a shaped object with high dimensional accuracy, it is preferable that start and stop of the discharge of a molten material from the nozzle can be switched in addition to stabilizing an amount of the molten material discharged from the nozzle, as in the device described above. The inventor of the present application has found that, in the device including a mechanism configured to switch between the start and stop of the discharge of the molten material from the nozzle, if the pressure value measured by the pressure gauge varies when the discharge of the molten material from the nozzle is stopped, rotation of the screw becomes unstable, and when the discharge of the molten material from the nozzle is restarted, it may be difficult to stably discharge the molten material from the nozzle. 
     SUMMARY 
     According to one aspect of the present disclosure, a three-dimensional shaping device is provided. The three-dimensional shaping device includes: a plasticization unit having a screw and configured to plasticize a material into a shaping material using the rotating screw; a drive unit configured to rotate the screw; a supply flow path communicating with the plasticization unit and through which the shaping material flows; a nozzle communicating with the supply flow path and configured to discharge the shaping material; a discharge amount adjusting mechanism having a valve portion provided in the supply flow path, and configured to switch between stop and restart of discharging of the shaping material from the nozzle by driving the valve portion; a pressure measuring portion configured to measure a pressure of the shaping material in the supply flow path between the plasticization unit and the valve portion; and a control unit configured to adjust rotation of the screw by controlling the drive unit according to a measured value of the pressure measured by the pressure measuring portion. The control unit controls the drive unit under a first control during a period when the discharging of the shaping material from the nozzle is not stopped by the discharge amount adjusting mechanism, and controls the drive unit under a second control during a period when the discharging of the shaping material from the nozzle is stopped by the discharge amount adjusting mechanism, and a degree of adjustment of the rotation of the screw under the second control is smaller than a degree of adjustment of the rotation of the screw under the first control. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a schematic configuration of a three-dimensional shaping device according to a first embodiment. 
         FIG. 2  is a schematic perspective view showing a configuration of a flat screw on a groove forming surface side. 
         FIG. 3  is a top view showing a configuration of a barrel on a screw facing surface side. 
         FIG. 4  is a perspective view showing a configuration of a valve portion of a discharge amount adjusting mechanism. 
         FIG. 5  is a diagram showing a configuration of the discharge amount adjusting mechanism and a suction portion. 
         FIG. 6  is a first diagram showing an operation of the valve portion of the discharge amount adjusting mechanism. 
         FIG. 7  is a second diagram showing an operation of the valve portion of the discharge amount adjusting mechanism. 
         FIG. 8  is a diagram showing an operation of a plunger of the suction portion. 
         FIG. 9  is a flowchart showing contents of a shaping processing. 
         FIG. 10  is a diagram schematically showing a state where a three-dimensional shaped object is shaped. 
         FIG. 11  is a flowchart showing contents of a pressure adjusting processing according to the first embodiment. 
         FIG. 12  is a graph showing an example of a relationship between a screw rotation speed and a pressure value. 
         FIG. 13  is a graph showing an example of a relationship between the screw rotation speed and time. 
         FIG. 14  is a graph showing an example of a relationship between the pressure value and time. 
         FIG. 15  is a diagram showing a schematic configuration of a three-dimensional shaping device according to a second embodiment. 
         FIG. 16  is a diagram showing a schematic configuration of a three-dimensional shaping device according to a third embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A. First Embodiment 
       FIG. 1  is a diagram showing a schematic configuration of a three-dimensional shaping device  100  according to a first embodiment.  FIG. 1  shows arrows along X, Y, and Z directions orthogonal to each other. The X direction and the Y direction are directions along a horizontal direction, and the Z direction is a direction along a vertical direction. In other figures, the arrows along the X, Y, and Z directions are appropriately shown. The X, Y, Z directions in  FIG. 1  and the X, Y, Z directions in other figures represent the same direction. 
     The three-dimensional shaping device  100  according to the present embodiment includes a shaping unit  200 , a stage  300 , a moving mechanism  400 , and a control unit  500 . Under control of the control unit  500 , the three-dimensional shaping device  100  shapes a three-dimensional shaped object in which layers of a shaping material are stacked on a shaping surface  310  by driving the moving mechanism  400  to change a relative position between a nozzle hole  69  and the shaping surface  310  while discharging the shaping material from the nozzle hole  69  provided in the shaping unit  200  toward the shaping surface  310  of the stage  300 . The shaping material is sometimes referred to as a molten material. A detailed configuration of the shaping unit  200  will be described later. 
     The moving mechanism  400  changes the relative position between the nozzle hole  69  and the shaping surface  310  as described above. According to the present embodiment, the moving mechanism  400  supports the stage  300 , and changes the relative position between the nozzle hole  69  and the shaping surface  310  by moving the stage  300  with respect to the shaping unit  200 . The moving mechanism  400  according to the present embodiment is implemented by a three-axis positioner that moves the stage  300  in three axial directions of the X, Y, and Z directions by drive forces of three motors. The motor is driven under the control of the control unit  500 . The moving mechanism  400  may be configured to change the relative position between the nozzle hole  69  and the shaping surface  310  by, instead of moving the stage  300 , moving the shaping unit  200  without moving the stage  300 . In addition, the moving mechanism  400  may be configured to change the relative position between the nozzle hole  69  and the shaping surface  310  by moving both the stage  300  and the shaping unit  200 . 
     The control unit  500  is implemented by a computer including one or more processors, a main storage device, and an input and output interface for inputting and outputting signals to and from an outside. According to the present embodiment, the control unit  500  controls operations of the shaping unit  200  and the moving mechanism  400  by the processor executing a program or a command read in the main storage device, so as to execute a shaping processing for shaping a three-dimensional shaped object. The operations include changing a three-dimensional relative position between the shaping unit  200  and the stage  300 . The control unit  500  may be implemented by a combination of a plurality of circuits instead of a computer. 
     The shaping unit  200  includes a material supply unit  20  that is a supply source of a material, a drive unit  35 , a plasticization unit  30  configured to plasticize the material supplied from the material supply unit  20  into a shaping material, a nozzle  61  having the nozzle hole  69  configured to discharge the shaping material supplied from the plasticization unit  30 , a discharge amount adjusting mechanism  70  configured to adjust a flow rate of the shaping material discharged from the nozzle  61 , a pressure measuring portion  80  configured to measure pressure of the shaping material, and a suction portion  90  configured to suck the shaping material. The “plasticization” means that a material having thermoplasticity is heated and melted. The “melting” also means that a material having thermoplasticity is softened by being heated to a temperature equal to or higher than a glass transition point, and exhibits fluidity. 
     A material in a state of pellets, powder, or the like is accommodated in the material supply unit  20 . According to the present embodiment, a pellet-shaped ABS resin is used as the material. The material supply unit  20  according to the present embodiment is implemented by a hopper. Below the material supply unit  20 , a supply path that couples the material supply unit  20  and the plasticization unit  30  is provided. The material supply unit  20  supplies the material to the plasticization unit  30  via the supply path  22 . 
     According to the embodiment, the drive unit  35  includes a drive motor  36 . The drive motor  36  is fixed to an upper surface of a screw case  31  to be described later. A rotation shaft of the drive motor  36  is coupled to an upper surface  41  of the flat screw  40  to be described later. The drive motor  36  is driven under the control of the control unit  500  to rotate the flat screw  40 . 
     The plasticization unit  30  includes the screw case  31 , the flat screw  40 , and a barrel  50 . The plasticization unit  30  melts at least a part of a solid-state material supplied from the material supply unit  20 , converts the material into a paste-shaped shaping material having fluidity, and supplies the material to the nozzle  61 . 
     The screw case  31  is a case for accommodating the flat screw  40 . The barrel  50  is fixed to a lower surface of the screw case  31 , and the flat screw  40  is accommodated in a space surrounded by the screw case  31  and the barrel  50 . 
     The flat screw  40  has a substantially columnar shape whose height in a direction along a central axis RX is smaller than a diameter of the flat screw  40 . The flat screw  40  is disposed in the screw case  31  such that the central axis RX is parallel to the Z direction. The flat screw  40  rotates around the central axis RX in the screw case  31  due to a torque generated by the drive motor  36 . The flat screw  40  includes a groove forming surface  42  at which groove portions  45  are formed on a side opposite to the upper surface  41  in the direction along the central axis RX. A specific configuration of the flat screw  40  on a groove forming surface  42  side will be described later. 
     The barrel  50  is disposed below the flat screw  40 . The barrel  50  includes a screw facing surface  52  that faces the groove forming surface  42  of the flat screw  40 . The barrel  50  is provided with an opening portion at a center of the screw facing surface  52 , a through hole  56  passing through the barrel  50  along the Z direction, and a cross hole  57  extending in the Y direction so as to intersect the through hole  56 . The through hole  56  forms a flow path for supplying the shaping material to the nozzle  61 . A specific configuration of the barrel  50  on a screw facing surface  52  side will be described later. 
     The barrel  50  is provided with a heater  58  for heating a material supplied to the groove portion  45  of the flat screw  40 . According to the present embodiment, four rod-shaped heaters  58  are disposed along the Y direction. The heaters  58  are disposed below the screw facing surface  52 . Temperatures of the heaters  58  are controlled by the control unit  500 . The heater  58  may be referred to as a heating portion. 
     A refrigerant pipe  59  through which a refrigerant flows is provided in the barrel  50  at a position farther from the through hole  56  than the heater  58 . The refrigerant pipe  59  is disposed so as to pass through a vicinity of an outer peripheral edge of the screw facing surface  52 . The refrigerant pipe  59  is coupled to a refrigerant pump  103 . The refrigerant pump  103  supplies the refrigerant to the refrigerant pipe  59 . The refrigerant pump  103  is driven under the control of the control unit  500 . As the refrigerant, for example, a liquid such as water or oil, or a gas such as carbon dioxide can be used. When the refrigerant flows through the refrigerant pipe  59 , it is possible to prevent temperatures of the flat screw  40  and the barrel  50  from becoming too high. The refrigerant pipe  59  and the refrigerant pump  103  may be referred to as a cooling portion. 
     The discharge amount adjusting mechanism  70  includes a valve portion  73  provided in the cross hole  57  of the barrel  50 , and a valve drive unit  101  configured to rotate the valve portion  73 . The valve portion  73  adjusts the flow rate of the shaping material supplied to the nozzle  61  by rotating in the cross hole  57 . The valve drive unit  101  is implemented by an actuator such as a stepping motor, and rotates the valve portion  73  under the control of the control unit  500 . In a flow path of the shaping material formed in the barrel  50 , a portion closer to the screw facing surface  52  than the valve portion  73  is referred to as a first flow path  151 , and a portion farther from the screw facing surface  52  than the valve portion  73  is referred to as a second flow path  152 . According to the present embodiment, in the through hole  56  of the barrel  50 , the portion closer to the screw facing surface  52  than the valve portion  73  is referred to as the first flow path  151 , and the portion farther from the screw facing surface  52  than the valve portion  73  is referred to as the second flow path  152 . A specific configuration of the discharge amount adjusting mechanism  70  will be described later. 
     The pressure measuring portion  80  is provided in the first flow path  151 . According to the present embodiment, the pressure measuring portion  80  is implemented by a pressure sensor. The pressure measuring portion  80  measures pressure of the shaping material in the first flow path  151 . A pressure value of the shaping material measured by the pressure measuring portion  80  is transmitted to the control unit  500 . 
     The suction portion  90  is coupled to the second flow path  152 . The suction portion  90  sucks the shaping material from the second flow path  152 . A specific configuration of the suction portion  90  will be described later. 
     The nozzle  61  is coupled to a lower surface of the barrel  50 . The nozzle  61  is provided with a nozzle flow path  68  and the nozzle hole  69 . The nozzle flow path  68  is a flow path provided in the nozzle  61 . The nozzle flow path  68  is coupled to the second flow path  152 . The nozzle hole  69  is a portion in which a flow path cross section provided at an end portion on a side of the nozzle flow path  68  communicating with atmosphere is reduced. The shaping material flowing into the nozzle flow path  68  from the second flow path  152  is discharged from the nozzle hole  69 . The flow rate of the shaping material discharged from the nozzle holes  69  is adjusted by the discharge amount adjusting mechanism  70 . A flow rate of the shaping material discharged from the nozzle  61  is also referred to as a discharge amount. According to the present embodiment, an opening shape of the nozzle hole  69  is a circle. A diameter of an opening portion of the nozzle hole  69  is referred to as a nozzle diameter Dn. An opening shape of the nozzle hole  69  is not limited to a circle, and may be a square or the like. When the opening shape of the nozzle hole  69  is a square, a length of one side of the square is referred to as the nozzle diameter Dn. The opening shape of the nozzle hole  69  may be a polygon other than the square. 
       FIG. 2  is a schematic perspective view showing the configuration of the flat screw  40  on the groove forming surface  42  side. In  FIG. 2 , a position of the central axis RX of the flat screw  40  is shown by a dashed line. As described with reference to  FIG. 1 , the groove portions  45  are provided in the groove forming surface  42 . 
     A central portion  47  of the groove forming surface  42  of the flat screw  40  is implemented as a recess to which one end of the groove portion  45  is coupled. The central portion  47  faces the through hole  56  of the barrel  50  shown in  FIG. 1 . The central portion  47  intersects the central axis RX. 
     The groove portion  45  of the flat screw  40  forms a so-called scroll groove. The groove portion  45  extends spirally from the central portion  47  toward an outer periphery of the flat screw  40  so as to draw an arc. The groove portion  45  may extend spirally. The groove forming surface  42  is provided with ridge portions  46  that form side wall portions of the groove portions  45  and extend along each of the groove portions  45 . 
     The groove portion  45  extends to a material introduction port  44  formed in a side surface  43  of the flat screw  40 . The material introduction port  44  is a portion that receives the material supplied via the supply path  22  of the material supply unit  20 . 
       FIG. 2  shows an example of the flat screw  40  including three groove portions  45  and three ridge portions  46 . The number of the groove portions  45  or the ridge portions  46  provided on the flat screw  40  is not limited to three. The flat screw  40  may be provided with only one groove portion  45 , or may be provided with two or more groove portions  45 . Any number of the ridge portions  46  may be provided in accordance with the number of the groove portions  45 . 
       FIG. 2  illustrates an example of the flat screw  40  in which the material introduction ports  44  are formed at three places. The number of the material introduction ports  44  provided in the flat screw  40  is not limited to three. In the flat screw  40 , the material introduction port  44  may be provided at only one place, or may be provided at two or more places. 
       FIG. 3  is a top view showing the configuration of the barrel  50  on the screw facing surface  52  side. As described above, the through hole  56  communicating with the nozzle  61  is formed at the center of the screw facing surface  52 . A plurality of guide grooves  54  are formed around the through hole  56  in the screw facing surface  52 . One end of the guide groove  54  is coupled to the through hole  56 , and extends spirally from the through hole  56  toward an outer periphery of the screw facing surface  52 . The guide groove  54  has a function of guiding the shaping material to the through hole  56 . 
       FIG. 4  is a perspective view showing a configuration of the valve portion  73  of the discharge amount adjustment mechanism  70  according to the present embodiment.  FIG. 5  is a diagram showing a configuration of the discharge amount adjusting mechanism  70  and the suction portion  90  according to the present embodiment. As described above, the discharge amount adjusting mechanism  70  has the valve portion  73  disposed in the cross hole  57 . The valve portion  73  has a columnar shape centered on a central axis AX 1 . The valve portion  73  is provided with a recessed portion  75  by partially cutting out a part of a columnar outer periphery in a half-moon shape. The recessed portion  75  is disposed between the first flow path  151  and the second flow path  152 . An operation portion  77  is provided at an end portion of the valve portion  73  on a −Y direction side. The valve drive unit  101  is coupled to the operation portion  77 . The valve portion  73  rotates when a torque by the valve drive unit  101  is applied to the operation portion  77 . The recessed portion  75  may be provided by forming a through hole intersecting the central axis AX 1  of the valve portion  73  in the valve portion  73 . The recessed portion  75  may also be referred to as a flow path. 
       FIG. 6  is a first diagram showing an operation of the valve portion  73  of the discharge amount adjusting mechanism  70 .  FIG. 7  is a second diagram showing an operation of the valve portion  73  of the discharge amount adjusting mechanism  70 . As shown in  FIG. 6 , when the valve portion  73  rotates such that the recessed portion  75  is positioned upward, an opening portion of the second flow path  152  is closed by the valve portion  73 , and a flow of the shaping material from the first flow path  151  into the second flow path  152  is blocked. On the other hand, as shown in  FIG. 7 , when the valve portion  73  rotates such that the recessed portion  75  faces the +X direction or the −X direction, the first flow path  151  communicates with the second flow path  152 , and the shaping material flows from the first flow path  151  into the second flow path  152  at a maximum flow rate. By the valve portion  73  rotating about the central axis AX 1  along the Y direction to change a position of the recessed portion  75 , a flow path cross-sectional area between the first flow path  151  and the second flow path  152  is changed, and a flow rate of the shaping material flowing from the first flow path  151  into the second flow path  152  is adjusted. The discharge amount adjusting mechanism  70  may be implemented by, for example, a gate valve, a globe valve, or a ball valve, instead of one including the valve portion  73  described above. 
     Referring to  FIG. 5 , the suction portion  90  according to the present embodiment includes a cylindrical cylinder  92  provided in the barrel  50 , a columnar plunger  93  accommodated in the cylinder  92 , and a plunger drive unit  102  configured to move the plunger  93  within the cylinder  92 . The cylinder  92  is coupled to the second flow path  152 . The plunger drive unit  102  is implemented by a stepping motor driven under the control of the control unit  500 , and a rack and pinion mechanism that converts a rotation of the stepping motor into a translational movement of the cylinder  92  along a central axis AX 2  thereof. The plunger drive unit  102  may be implemented by the stepping motor driven under the control of the control unit  500 , and a ball screw mechanism that converts the rotation of the stepping motor into the translational movement of the cylinder  92  along the central axis AX 2  thereof, or may be implemented by an actuator such as a solenoid mechanism or a piezo element. 
       FIG. 8  is a diagram showing an operation of the plunger  93  of the suction portion  90 . When the plunger  93  moves in a direction away from the second flow path  152 , a negative pressure is generated in the cylinder  92 , so that the shaping material in the second flow path  152  is drawn into the cylinder  92  as shown by an arrow in  FIG. 8 . As the shaping material in the second flow path  152  is drawn into the cylinder  92 , the shaping material in the nozzle  61  is drawn into the second flow path  152 . Therefore, when discharge of the shaping material from the nozzle hole  69  is stopped, the shaping material in the second flow path  152  is sucked into the cylinder  92 , so that the shaping material discharged from the nozzle hole  69  can be cut off. On the other hand, when the plunger  93  moves in a direction approaching the second flow path  152 , the shaping material in the cylinder  92  is pushed out into the second flow path  152  by the plunger  93 . Therefore, when the discharge of the shaping material from the nozzle hole  69  is restarted, a response of the discharge of the shaping material from the nozzle hole  69  can be enhanced by pushing the shaping material in the cylinder  92  out into the second flow path  152 . Moving the plunger  93  in a direction in which the shaping material is pushed out from the cylinder  92  may be referred to as pushing the plunger  93 . Moving the plunger  93  in a direction in which the shaping material is drawn into the cylinder  92  may be referred to as pulling the plunger  93 . 
       FIG. 9  is a flowchart showing contents of a shaping processing according to the present embodiment. When a predetermined start operation is performed by a user on an operation panel provided in the three-dimensional shaping device  100  or a computer coupled to the three-dimensional shaping device  100 , the shaping processing is executed by the control unit  500 . 
     First, in step S 110 , the control unit  500  acquires shaping data for shaping the three-dimensional shaped object. The shaping data represents information such as a movement path of the nozzle hole  69  with respect to the stage  300 , an amount of the shaping material discharged from the nozzle hole  69 , a target rotation speed of the drive motor  36  for rotating the flat screw  40 , and a target temperature of the heater  58  provided in the barrel  50 . The shaping data is generated by, for example, slicer software installed in the computer that is coupled to the three-dimensional shaping device  100 . The slicer software reads shape data representing a shape of the three-dimensional shaped object created using three-dimensional CAD software or three-dimensional CG software, divides the shape of the three-dimensional shaped object into layers having a predetermined thickness, and generates the shaping data. Data in an STL format or an AMF format can be used for the shape data read into the slicer software. The shaping data created by the slicer software is shown with a G code, an M code, or the like. The control unit  500  acquires the shaping data from the computer coupled to the three-dimensional shaping device  100  or a recording medium such as a USB memory. 
     Next, in step S 120 , the control unit  500  starts generating a shaping material. The control unit  500  controls the rotation of the flat screw  40  and the temperature of the heater  58  provided in the barrel  50 , so as to melt the material and generate the shaping material. By the rotation of the flat screw  40 , the material supplied from the material supply unit  20  is introduced into the groove portion  45  from the material introduction port  44  of the flat screw  40 . The material introduced into the groove portion  45  is transported along the groove portion  45  to the central portion  47 . The material transported in the groove portion  45  is sheared by a relative rotation between the flat screw  40  and the barrel  50 , and at least a part of the material is melted by heating with the heater  58  to become the paste-shaped shaping material having fluidity. The shaping material collected in the central portion  47  is supplied to the first flow path  151  by an internal pressure generated in the central portion  47 . The shaping material continues to be generated while the processing is performed. 
     After the generation of the shaping material is started in step S 120 , in step S 200 , the control unit  500  starts executing a pressure adjusting processing for stabilizing the pressure of the shaping material in the first flow path  151 . The pressure adjusting processing is executed in parallel with the shaping processing while the flat screw  40  is rotated to generate the shaping material. The specific contents of the pressure adjusting processing will be described later. 
     Thereafter, in step S 130 , the control unit  500  controls the valve drive unit  101  to rotate the valve portion  73 , thereby causing communication between the first flow path  151  and the second flow path  152 . With the communication between the first flow path  151  and the second flow path  152 , the discharge of the shaping material from the nozzle hole  69  is started. 
     In step S 140 , the control unit  500  shapes the three-dimensional shaped object by discharging the shaping material from the nozzle hole  69  toward the stage  300  while controlling the moving mechanism  400  to change the relative position between the nozzle hole  69  and the stage  300  according to the shaping data. 
     In step S 150 , the control unit  500  determines whether to stop the discharge of the shaping material from the nozzle hole  69 . The control unit  500  determines whether to stop the discharge of the shaping material from the nozzle hole  69  based on the shaping data. For example, when a target position of the nozzle hole  69  is set at a position far from a current position of the nozzle hole  69  discharging the shaping material, the control unit  500  determines to stop the discharge of the shaping material from the nozzle hole  69 . When it is determined in step S 150  that the discharge of the shaping material from the nozzle hole  69  is not stopped, the control unit  500  returns the processing to step S 140  to continue the shaping of the three-dimensional shaped object. 
     When it is determined in step S 150  to stop the discharge of the shaping material from the nozzle hole  69 , in step S 160 , the control unit  500  controls the valve drive unit  101  to rotate the valve portion  73 , so as to block the flow of the shaping material from the first flow path  151  into the second flow path  152 . By blocking the flow of the shaping material from the first flow path  151  into the second flow path  152 , the discharge of the shaping material from the nozzle hole  69  is stopped. When the discharge of the shaping material from the nozzle hole  69  is stopped, in step S 165 , the control unit  500  controls the plunger drive unit  102  to pull the plunger  93 , so as to suck the shaping material in the second flow path  152  into the cylinder  92 . Therefore, the discharge of the shaping material from the nozzle hole  69  is immediately stopped. The shaping of the three-dimensional shaped object is stopped while the discharge of the shaping material from the nozzle hole  69  is stopped. 
     In step S 170 , the control unit  500  determines whether to restart the discharge of the shaping material from the nozzle hole  69 . When it is determined in step S 170  to restart the discharge of the shaping material from the nozzle hole  69 , in step S 180 , the control unit  500  controls the valve drive unit  101  to rotate the valve portion  73 , thereby causing the communication between the first flow path  151  and the second flow path  152 . When the discharge of the shaping material from the nozzle hole  69  is restarted, in step S 185 , the control unit  500  controls the plunger drive unit  102  to push the plunger  93 , so as to push the shaping material in the cylinder  92  out into the second flow path  152 . Therefore, the discharge of the shaping material from the nozzle hole  69  is immediately restarted. Thereafter, the control unit  500  returns the processing to step S 140 , and the shaping of the three-dimensional shaped object is restarted. 
     When it is determined in step S 170  that the discharge of the shaping material from the nozzle hole  69  is not restarted, in step S 190 , the control unit  500  determines whether the shaping of the three-dimensional shaped object is completed. The control unit  500  can determine whether the shaping of the three-dimensional shaped object is completed based on the shaping data. When it is determined in step S 190  that the shaping of the three-dimensional shaped object is not completed, the control unit  500  returns the processing to step S 170  and determines again whether to restart the discharge of the shaping material from the nozzle hole  69 . On the other hand, when it is determined in step S 190  that the shaping of the three-dimensional shaped object is completed, the control unit  500  ends this processing. 
       FIG. 10  is a diagram schematically showing a state where a three-dimensional shaped object OB is shaped. The control unit  500  executes the shaping processing described above, so that the three-dimensional shaped object OB in which a plurality of layers of the shaping material are stacked is shaped on the stage  300 . 
       FIG. 11  is a flowchart showing contents of the pressure adjusting processing. This processing is executed by the control unit  500  after the generation of the shaping material is started in the shaping processing described with reference to  FIG. 9 . 
     First, in step S 205 , the control unit  500  sets a type of material used for shaping the three-dimensional shaped object OB, a collection time T, a target pressure value Pb, and a pressure tolerance ΔP. The collection time T means a time for collecting a pressure value of the shaping material in the first flow path  151  by the pressure measuring portion  80 . The target pressure value Pb means a target value of pressure of the shaping material in the first flow path  151 . The pressure tolerance ΔP means an allowable range of deviation of the pressure of the shaping material in the first flow path  151  from the target pressure value Pb. According to the present embodiment, by specifying the type of material, the collection time T, the target pressure value Pb, and the pressure tolerance ΔP in advance by the user using a computer coupled to the three-dimensional shaping device  100 , the type of material, the collection time T, the target pressure value Pb, and the pressure tolerance ΔP are represented in the shaping data. The control unit  500  acquires the type of material, the collection time T, the target pressure value Pb, and the pressure tolerance ΔP by acquiring the shaping data from the computer coupled to the three-dimensional shaping device  100 . 
     Next, in step S 210 , the control unit  500  determines whether the valve portion  73  is open. For example, the control unit  500  can use the shaping data to determine whether the valve portion  73  is open. When it is determined in step S 210  that the valve portion  73  is not open, the control unit  500  proceeds the processing to step S 255  to determine whether to end the pressure adjusting processing. According to the present embodiment, when there is a command to stop the rotation of the flat screw  40 , the control unit  500  determines to end the pressure adjusting processing. When it is determined to end the pressure adjusting processing, the control unit  500  ends this processing. On the other hand, when it is determined not to end the pressure adjusting processing, the control unit  500  returns the processing to step S 210  and determines again whether to open the valve portion  73 . 
     When it is determined in step S 210  that the valve portion  73  is open, in step S 215 , the control unit  500  uses the pressure measuring portion  80  to acquire the pressure value P, which is the pressure value of the shaping material in the first flow path  151 . The acquired pressure value P is stored in a storage device of the control unit  500 . Thereafter, in step S 220 , the control unit  500  determines whether a time t from a start of acquisition of the pressure value P is equal to or more than the collection time T. When it is determined in step S 220  that the time t is less than the collection time T, the control unit  500  repeats the processing from step S 210  to step S 220  until it is determined in step S 220  that the time t is equal to or more than the collection time T, and acquires a plurality of samples of pressure values P at a preset time interval. This time interval is set, for example, to one second. The collection time T is set to, for example, ten seconds. In this case, the control unit  500  acquires a sample of the pressure value P once every one second during ten seconds. That is, the control unit  500  acquires ten samples of the pressure values P within the collection time T. Thereafter, in step S 210 , the control unit  500  may determine whether a predetermined number of samples of the pressure values P are acquired, instead of determining whether the time t is equal to or more than the collection time T. 
     On the other hand, when it is determined in step S 220  that the time t is equal to or more than the collection time T, in step S 225 , the control unit  500  calculates an average value of the plurality of pressure values P acquired within the collection time T. According to the present embodiment, the control unit  500  uses a total pressure value ΣP n  that is a total value from a first acquired pressure value P 1  to an n-th acquired pressure value P n  and a number N of samples of the pressure values P acquired within the collection time T to calculate an average pressure value Pave expressed by the following Formula (1). 
     
       
         
           
             
               
                 
                   Pave 
                   = 
                   
                     Σ 
                     ⁢ 
                     
                       
                         P 
                         n 
                       
                       / 
                       N 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     According to the present embodiment, in step S 225 , the control unit  500  calculates the average pressure value Pave by calculating a moving average of the plurality of acquired pressure values P. For example, when the values from the first pressure value P 1  to the n-th pressure value P n  are acquired, the control unit  500  calculates the average pressure value Pave by dividing the total value (P 1 +P 2 +P 3 + . . . +P n ) from P 1  to P n  by the number of samples N from P 1  to P n . Thereafter, when an (n+1)-th pressure value P n+1  is acquired, the control unit  500  calculates an average pressure value Pave by dividing a total value (P 2 +P 3 +P 4 + . . . +P n +P n+1 ) from a second pressure value P 2  to the (n+1)-th pressure value P n+1  by the number of samples N. 
     Next, in step S 230 , the control unit  500  determines whether the average pressure value Pave is within a predetermined allowable range. When the average pressure value Pave is equal to or less than a first threshold value obtained by adding the pressure tolerance ΔP to the target pressure value Pb, and the average pressure value Pave is equal to or more than a second threshold value obtained by subtracting the pressure tolerance ΔP from the target pressure value Pb, the control unit  500  determines that the average pressure value Pave is within the allowable range. When it is determined in step S 230  that the average pressure value Pave is within the allowable range, the control unit  500  proceeds the processing to step S 255  to determine whether to end the pressure adjusting processing. On the other hand, when it is determined in step S 230  that the average pressure value Pave is not within the allowable range, in step S 235 , the control unit  500  uses the average pressure value Pave and the target pressure value Pb to calculate a pressure difference Pd expressed by the following Formula (2). 
     
       
         
           
             
               
                 
                   Pd 
                   = 
                   
                     Pave 
                     - 
                     Pb 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     In step S 240 , the control unit  500  determines whether the pressure difference Pd is a positive value. When it is determined in step S 240  that the pressure difference Pd is a positive value, in other words, when it is determined that the average pressure value Pave is greater than the target pressure value Pb, in step S 245 , the control unit  500  decreases the rotation speed of the flat screw  40  so that the pressure difference Pd approaches 0. The rotation speed of the flat screw  40  is referred to as a screw rotation speed. The rotation speed means the number of times an object rotates per unit time. According to the present embodiment, in step S 240 , the control unit  500  refers to a table in which a relationship between the screw rotation speed and the pressure is expressed, so as to calculate a correction value of the screw rotation speed, and calculate a new screw rotation speed obtained by subtracting the correction value from a current screw rotation speed. The table in which the relationship between the screw rotation speed and the pressure is expressed can be set by a test performed in advance. The control unit  500  controls the drive motor  36  to obtain a new screw rotation speed, thereby decreasing the screw rotation speed. Instead of referring to the table, the control unit  500  may use a preset function to calculate a new screw rotation speed. 
     On the other hand, when it is determined in step S 240  that the pressure difference Pd is not a positive value, in other words, when it is determined that the average pressure value Pave is smaller than the target pressure value Pb, in step S 250 , the control unit  500  increases the rotation speed of the flat screw  40  so that the pressure difference Pd approaches 0. According to the present embodiment, in step S 245 , the control unit  500  refers to the table in which the relationship between the screw rotation speed and the pressure is expressed, so as to calculate a correction value of the screw rotation speed, and calculate a new screw rotation speed obtained by adding the correction value to the current screw rotation speed. The control unit  500  controls the drive motor  36  to obtain a new screw rotation speed, thereby increasing the screw rotation speed. The control performed by the control unit  500  during a period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70  may be referred to as a first control, and the control performed by the control unit  500  during a period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70  may be referred to as a second control. A degree of adjustment of the rotation of the flat screw  40  under the second control is smaller than a degree of adjustment of the rotation of the flat screw  40  under the first control. The degree of adjustment of the rotation of the flat screw  40  means a magnitude of a change in the rotation speed of the flat screw  40  by adjustment. A small degree of adjustment of the rotation of the flat screw  40  means not only that the change in the rotation speed of the flat screw  40  by the adjustment is small, but also that the rotation of the flat screw  40  is not adjusted. 
     Thereafter, in step S 255 , the control unit  500  determines whether to stop the pressure adjusting processing. According to the present embodiment, when there is a command to stop the rotation of the flat screw  40 , the control unit  500  determines to end the pressure adjusting processing. When it is determined to end the pressure adjusting processing in step S 255 , the control unit  500  ends this processing. On the other hand, when it is determined not to end the pressure adjusting processing in step S 255 , the control unit  500  returns the processing to step S 210 , and repeats the processing from step S 210 . At this time, as described above, the control unit  500  calculates the average pressure value Pave by calculating the moving average of the plurality of acquired pressure values P. Therefore, for example, in step S 215 , when the (n+1)-th pressure value P n+1  is acquired, in step S 225 , the average pressure value Pave is calculated by dividing the total value (P 2 +P 3 +P 4 + . . . +P n +P n+1 ) from the second pressure value P 2  to the (n+1)-th pressure value P n+1  by the number of samples N. 
       FIG. 12  is a graph showing an example of a relationship between the screw rotation speed and the pressure value P. A horizontal axis shows the screw rotation speed. A vertical axis shows the pressure value P. The relationship between the screw rotation speed and the pressure value P when ABS resin is used as the material is shown by a solid line, and the relationship between the screw rotation speed and the pressure value P when polypropylene resin (PP) is used as the material is shown by a dashed line. In  FIG. 12 , as an example, the relationship between the screw rotation speed and the pressure value P is expressed when the temperature of the heater  58  is 210°, the opening shape of the nozzle hole  69  is circle, and the nozzle diameter Dn is 1.0 mm. 
       FIG. 13  is a graph showing an example of a relationship between the screw rotation speed and time. The horizontal axis shows time. The vertical axis shows the screw rotation speed. When the rotation of the flat screw is adjusted by the pressure adjusting processing described above, the control unit  500  adjusts a screw rotation speed Na, as shown by a solid line in  FIG. 13 , by controlling the drive motor  36  so that a difference between the measured pressure value P and the target pressure value Pb approaches 0. On the other hand, when the rotation of the flat screw  40  is not adjusted, the control unit  500  controls the drive motor  36  such that the screw rotation speed is kept at a preset constant rotation speed Nc as shown by a two-dot chain line in  FIG. 13 . 
       FIG. 14  is a graph showing an example of a relationship between the pressure value and time. The horizontal axis shows time. The vertical axis shows the pressure of the shaping material in the first flow path  151 . When the rotation speed of the flat screw  40  is adjusted by the pressure adjusting processing described above, as shown by a solid line in  FIG. 14 , variations in pressure due to disturbance such as an increase or decrease in the temperature around the three-dimensional shaping device  100  and vibrations applied to the three-dimensional shaping device  100  is prevented, and a measured pressure value Pa approaches the target pressure value Pb. On the other hand, when the rotation speed of the flat screw  40  is kept constant without being adjusted, as shown by a two-dot chain line in  FIG. 14 , due to the disturbance such as the increase or decrease in the temperature around the three-dimensional shaping device  100  and vibrations applied to the three-dimensional shaping device  100 , a measured pressure value Pc varies. For example, regardless of whether the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , when the rotation speed of the flat screw  40  is always kept constant, during the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70 , the pressure of the shaping material in the first flow path  151  varies, so that the discharge of the shaping material from the nozzle hole  69  becomes unstable. During the period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , the pressure of the shaping material in the first flow path  151  increases with time. On the other hand, regardless of whether the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , when the rotation speed of the flat screw  40  is adjusted according to the pressure of the shaping material in the first flow path  151 , during the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70 , the variation in the pressure of the shaping material in the first flow path  151  is prevented, so that the discharge of the shaping material from the nozzle hole  69  is prevented from becoming unstable. During the period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , in order to prevent an increase in the pressure of the shaping material in the first flow path  151 , the rotation speed of the flat screw  40  is reduced with time. Therefore, when the discharge of the shaping material from the nozzle hole  69  is restarted, the rotation speed of the flat screw is insufficient, and the discharge of the shaping material from the nozzle hole  69  becomes unstable. 
     According to the three-dimensional shaping device  100  of the present embodiment described above, during the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70 , the control unit  500  controls the drive motor  36  such that the degree of adjustment of the rotation speed of the flat screw  40  is increased, and during the period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , the control unit  500  controls the drive motor  36  such that the degree of adjustment of the rotation speed of the flat screw  40  is reduced. Therefore, during the period when the discharge of the shaping material from the nozzle hole  69  is stopped, it is difficult to adjust the rotation speed of the flat screw  40  even when the pressure of the shaping material in the first flow path  151  varies, so that when the discharge of the shaping material from the nozzle hole  69  is restarted, the insufficient rotation speed of the flat screw  40  and unstable discharge of the shaping material from the nozzle hole  69  can be prevented. In particular, according to the present embodiment, during the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70 , the control unit  500  controls the drive motor  36  such that the rotation speed of the flat screw  40  is adjusted according to the pressure of the shaping material in the first flow path  151 , and during the period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , the control unit  500  controls the drive motor  36  such that the rotation speed of the flat screw  40  is kept constant without being adjusted. Therefore, during the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70 , since the variation in the pressure of the shaping material in the first flow path  151  is prevented, the unstable discharge of the shaping material from the nozzle hole  69  can be prevented. During the period when the discharge of the shaping material from the nozzle hole  69  is stopped by the discharge amount adjusting mechanism  70 , even when the pressure of the shaping material in the first flow path  151  increases, the rotation speed of the flat screw  40  is kept constant. Therefore, the rotation speed of the flat screw  40  can be prevented from being reduced due to the discharge of the shaping material from the nozzle hole  69  being stopped by the discharge amount adjusting mechanism  70 , so that when the discharge of the shaping material from the nozzle hole  69  is restarted, the unstable discharge of the shaping material from the nozzle hole  69  can be prevented. 
     According to the present embodiment, when it is determined that the average pressure value Pave is not within the allowable range, the control unit  500  adjusts the rotation speed of the flat screw  40 , and when it is determined that the average pressure value Pave is within the allowable range, the control unit  500  does not adjust the rotation speed of the flat screw  40 . Therefore, the change in the rotation speed of the flat screw  40  is repeated due to a slight variation in pressure, so that it is possible to prevent the difficulty in stabilizing the discharge of the shaping material from the nozzle hole  69 . 
     According to the present embodiment, the control unit  500  uses the moving average of the plurality of pressure values P measured by the pressure measuring portion  80  to calculate the rotation speed of the flat screw  40 . Therefore, it is possible to prevent a case where it is difficult to stabilize the discharge of the shaping material from the nozzle hole  69  due to a sudden variation in the pressure value P generated during the pressure adjusting processing. 
     According to the present embodiment, the control unit  500  adjusts the rotation speed of the flat screw  40  with reference to the table in which the relationship between the rotation speed of the flat screw  40  and the pressure of the shaping material is expressed. Therefore, even when the relationship between the rotation speed of the flat screw  40  and the pressure of the shaping material is non-linear, the discharge of the shaping material from the nozzle hole  69  can be stabilized. 
     According to the present embodiment, the three-dimensional shaping device  100  includes the flat screw  40  having a short length along the Z direction, and the material can be plasticized to obtain the shaping material using the rotation of the flat screw  40 . Therefore, it is possible to reduce a size of the three-dimensional shaping device  100  in the Z direction. 
     According to the present embodiment, the discharge amount adjusting mechanism  70  includes the valve portion  73  that rotates in the cross hole  57 , and the stop and restart of the discharge of the shaping material from the nozzle hole  69  can be switched by the rotation of the valve portion  73 . Therefore, the stop and restart of the discharge of the shaping material from the nozzle hole  69  can be switched with a simple configuration. 
     According to the present embodiment, a pellet-shaped ABS resin is used as the material, whereas as a material used in the shaping unit  200 , for example, a material for shaping a three-dimensional shaped object using various materials such as a material having thermoplasticity, a metal material, and a ceramic material as a main material can also be used. Here, the “main material” means a central material for forming a shape of the three-dimensional shaped object, and a material occupying a content of 50% by weight or more in the three-dimensional shaped object. The above shaping materials include those in which main materials are melted alone, and those in which some of the contained components are melted together with the main materials to form a paste. 
     When a material having thermoplasticity is used as the main material, a shaping material is generated by plasticizing with the material in the plasticization unit  30 . The “plasticization” means that a material having thermoplasticity is heated and melted. The “melting” also means that a material having thermoplasticity is softened by being heated to a temperature equal to or higher than a glass transition point, and exhibits fluidity. 
     As a material having thermoplasticity, for example, a thermoplastic resin material obtained by combining one or more of the following can be used. 
     Example of Thermoplastic Resin Material 
     General-purpose engineering plastics such as a polypropylene resin (PP), a polyethylene resin (PE), a polyacetal resin (POM), a polyvinyl chloride resin (PVC), a polyamide resin (PA), an acrylonitrile-butadiene-styrene resin (ABS), a polylactic acid resin (PLA), a polyphenylene sulfide resin (PPS), polycarbonate (PC), modified polyphenylene ether, polybutylene terephthalate, and polyethylene terephthalate, and engineering plastics such as polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyimide, polyamideimide, polyetherimide, and polyetheretherketone (PEEK) 
     The material having thermoplasticity may contain pigments, metals, ceramics, and an additive such as a wax, a flame retardant, an antioxidant, and a heat stabilizer. The material having thermoplasticity is plasticized and melted by the rotation of the flat screw  40  and the heating with the heater  58  in the plasticization unit  30 . After the shaping material thus generated is discharged from the nozzle hole  69 , the shaping material is cured due to a reduction in temperature. 
     It is desirable that the material having thermoplasticity is discharged from the nozzle holes  69  in a state where the material is heated to a temperature equal to or higher than the glass transition point thereof and is in a state of being completely melted. The “state of being completely melted” means a state where a non-melted material having thermoplasticity does not exist, and means a state where, for example, when a pellet-shaped thermoplastic resin is used as the material, a pellet-shaped solid does not remain. 
     In the shaping unit  200 , for example, the following metal material may be used as a main material instead of the above material having thermoplasticity. In this case, it is desirable that a component to be melted at the time of generating the shaping material is mixed with a powder material obtained by converting the following metal material into a powder, and then the mixture is charged into the plasticization unit  30 . 
     Example of Metal Material 
     A single metal of magnesium (Mg), iron (Fe), cobalt (Co) or chromium (Cr), aluminum (Al), titanium (Ti), copper (Cu), and nickel (Ni), or an alloy containing one or more of these metals 
     Example of Alloy 
     Maraging steel, steel, stainless steel, cobalt chrome molybdenum, titanium alloy, nickel alloy, aluminum alloy, cobalt alloy, and cobalt chromium alloy 
     In the shaping unit  200 , a ceramic material can be used as a main material instead of the above metal material. As the ceramic material, for example, oxide ceramics such as silicon dioxide, titanium dioxide, aluminum oxide, and zirconium oxide, and non-oxide ceramics such as aluminum nitride can be used. When the above metal material or ceramic material is used as the main material, the shaping material disposed on the stage  300  may be cured by, for example, sintering with laser irradiation or warm air. 
     The powder material of the metal material or the ceramic material charged into the material supply unit  20  may be a mixed material obtained by mixing a plurality of types of powders of single metal powder, alloy powder, and ceramic material powder. The powder material of the metal material or the ceramic material may be coated with, for example, the thermoplastic resin shown above or another thermoplastic resin. In this case, the thermoplastic resin may be melted in the plasticization unit  30  to exhibit fluidity. 
     For example, the following solvents can be added to the powder material of the metal material or the ceramic material charged into the material supply unit  20 . The solvent can be used alone or in combination of two or more selected from the following. 
     Example of Solvent 
     Water, (poly)alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether, acetate esters such as ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, and iso-butyl acetate, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, ethyl-n-butyl ketone, diisopropyl ketone, and acetylacetone, alcohols such as ethanol, propanol, and butanol, tetraalkylammonium acetates, sulfoxide-based solvents such as dimethyl sulfoxide and diethyl sulfoxide, pyridine-based solvents such as pyridine, γ-picoline, and 2,6-lutidine, tetraalkylammonium acetates (such as tetrabutylammonium acetate), and ionic liquids such as butyl carbitol acetate 
     In addition, for example, the following binders can be added to the powder material of the metal material or the ceramic material charged into the material supply unit  20 . 
     Example of Binder 
     Acrylic resin, epoxy resin, silicone resin, cellulose resin or other synthetic resins, or polylactic acid (PLA), polyamide (PA), polyphenylene sulfide (PPS), polyetheretherketone (PEEK) or other thermoplastic resins 
     B. Second Embodiment 
       FIG. 15  is a diagram showing a schematic configuration of a three-dimensional shaping device  100   b  according to a second embodiment. The three-dimensional shaping device  100   b  according to the second embodiment is different from the first embodiment in that a waste material collection box  600  and a cleaning member  610  are provided. Other configurations are the same as those of the first embodiment shown in  FIG. 1  unless otherwise specified. 
     The waste material collection box  600  is provided adjacent to the stage  300 . The waste material collection box  600  has an opening portion on an upper surface thereof. The waste material collection box  600  accommodates the shaping material discharged from the nozzle holes  69 . The waste material collection box  600  is supported by the moving mechanism  400  and moves together with the stage  300  with respect to the nozzle  61 . 
     The cleaning member  610  is fixed inside the waste material collection box  600 . A tip end portion of the cleaning member  610  is positioned above the upper surface of the waste material collection box  600 . In the present embodiment, the cleaning member  610  is a brush disposed such that a bristle tip faces upward. The cleaning member  610  moves together with the waste material collection box  600  with respect to the nozzle  61  by the moving mechanism  400 . The cleaning member  610  may be a sheet made of resin or synthetic leather. 
     In the present embodiment, the control unit  500  executes a maintenance operation before the shaping of the three-dimensional shaped object is started or while the shaping of the three-dimensional shaped object is temporarily stopped. The maintenance operation includes an operation of discharging an old shaping material retained in the nozzle  61 , and an operation of cleaning the shaping material adhering to a tip end of the nozzle  61 . For example, when the shaping material retains in the first flow path  151 , the second flow path  152 , or the nozzle  61  for a long time, the retained shaping material may be denatured by influence of heat or the like. Therefore, the control unit  500  pauses the shaping of the three-dimensional shaped object at a predetermined timing, and executes the maintenance operation. For example, when it is determined in step S 170  of  FIG. 9  that the discharge of the shaping material from the nozzle hole  69  is restarted, the control unit  500  executes the maintenance operation. In the present embodiment, first, the control unit  500  controls the drive motor  36  such that a new shaping material is supplied to the first flow path  151 , and the old shaping material retained in the first flow path  151 , the second flow path  152 , or the nozzle  61  is pushed out by a new shaping material, and therefore, the old shaping material is discharged from the nozzle hole  69  toward the waste material collection box  600 . Next, the control unit  500  controls the moving mechanism  400  to bring the cleaning member  610  into contact with a tip end portion of the nozzle  61  to clean the shaping material and the like adhering to the tip end portion of the nozzle  61 . Thereafter, the shaping of the three-dimensional shaped object is restarted by the control unit  500 . 
     According to the present embodiment, the control unit  500  executes the pressure adjusting processing to adjust the rotation speed of the flat screw  40  in advance after the above maintenance operation and before restarting the shaping of the three-dimensional shaped object. The control unit  500  shapes the three-dimensional shaped object while generating the shaping material at the rotation speed of the flat screw  40  adjusted in advance during a period from when the shaping of the three-dimensional shaped object is restarted to when the shaping is paused. That is, the control unit  500  does not adjust the rotation speed of the flat screw  40  during the period from when the shaping of the three-dimensional shaped object is restarted to when the shaping is paused. According to the present embodiment, the control unit  500  starts discharging the shaping material from the nozzle hole  69  by the discharge amount adjusting mechanism  70 , and adjusts the rotation speed of the flat screw  40  in advance by performing the pressure adjusting processing while discharging the shaping material from the nozzle hole  69  to an outer peripheral portion of the shaping surface  310  of the stage  300 . Therefore, the rotation speed of the flat screw  40  can be adjusted in a state where a temperature in a vicinity of the nozzle  61  or the like is close to a temperature when the three-dimensional shaped object is shaped or the like. The control performed by the control unit  500  during the period after the maintenance operation and before restarting the shaping of the three-dimensional shaped object among the period when the discharge of the shaping material from the nozzle hole  69  is not stopped by the discharge amount adjusting mechanism  70  may be referred to as a third control. According to the present embodiment, under the third control, the rotation speed of the flat screw  40  is adjusted, and under the first control, the rotation speed of the flat screw  40  is not adjusted. Therefore, the degree of adjustment of the rotation of the flat screw  40  under the first control is smaller than the degree of adjustment of the rotation of the flat screw  40  under the third control. The control unit  500  may adjust the rotation speed of the flat screw  40  in advance by executing the pressure adjusting processing while discharging the shaping material from the nozzle hole  69  toward the waste material collection box  600 . 
     According to the three-dimensional shaping device  100   b  of the present embodiment described above, the control unit  500  adjusts the rotation speed of the flat screw  40  in advance by executing the pressure adjusting processing after the maintenance operation and before restarting the shaping of the three-dimensional shaped object. Therefore, it is possible to stabilize the discharge of the shaping material from the nozzle hole  69  after the shaping of the three-dimensional shaped object is restarted. In particular, according to the present embodiment, the control unit  500  adjusts the rotation speed of the flat screw  40  in advance by executing the pressure adjusting processing after the maintenance operation and before restarting the shaping of the three-dimensional shaped object, and rotates the flat screw  40  at the rotation speed adjusted in advance without executing the pressure adjusting processing during the period from when the shaping of the three-dimensional shaped object is restarted to when the shaping is paused. Therefore, the discharge of the shaping material from the nozzle hole  69  can be stabilized without complicating the processing during the shaping of the three-dimensional shaped object. 
     C. Third Embodiment 
       FIG. 16  is a diagram showing a schematic configuration of a three-dimensional shaping device  100   c  according to a third embodiment. The three-dimensional shaping device  100   c  according to the third embodiment is different from the first embodiment in that a second heater  160  is provided. Other configurations are the same as those of the first embodiment shown in  FIG. 1  unless otherwise specified. 
     The second heater  160  is provided in an outer periphery of the second flow path  152  in the barrel  50 . The second heater  160  heats the shaping material in the second flow path  152 . A temperature of the second heater  160  is controlled by the control unit  500 . The second heater  160  may also be referred to as a heating portion. 
     In the present embodiment, in the pressure adjusting processing, the control unit  500  adjusts the temperature of the second heater  160  instead of the rotation of the flat screw  40 . When it is determined in step S 240  shown in  FIG. 11  that the average pressure value Pave is greater than the target pressure value Pb, in step S 245 , the control unit  500  increases the temperature of the second heater  160  instead of decreasing the rotation speed of the flat screw  40 . When the temperature of the second heater  160  is increased, the fluidity of the shaping material increases, and thus the pressure value P measured by the pressure measuring portion  80  is reduced. Therefore, the pressure value P approaches the target pressure value Pb. On the other hand, when it is determined in step S 240  that the average pressure value Pave is smaller than the target pressure value Pb, in step S 250 , the control unit  500  decreases the temperature of the second heater  160  instead of increasing the rotation speed of the flat screw  40 . When the temperature of the second heater  160  is decreased, the fluidity of the shaping material decreases, and thus the pressure value P measured by the pressure measuring portion  80  is increased. Therefore, the pressure value P approaches the target pressure value Pb. In step S 245  or step S 250 , the control unit  500  may adjust both the rotation of the flat screw  40  and the temperature of the second heater  160 . In the pressure adjusting processing described in the second embodiment, the control unit  500  may adjust the temperature of the second heater  160  instead of the rotation of the flat screw  40 , or may adjust both the rotation of the flat screw  40  and the temperature of the second heater  160 . 
     According to the three-dimensional shaping device  100   c  of the present embodiment described above, the control unit  500  can prevent the variation of the pressure value P by adjusting the temperature of the second heater  160 . Therefore, the discharge of the shaping material from the nozzle hole  69  can be stabilized. 
     D. Other Embodiments 
     (D1) In the pressure adjusting processing of the embodiments described above, the control unit  500  may adjust the rotation speed of the flat screw  40  without using the pressure value P measured by the pressure measuring portion  80  during a period when the plunger  93  of the suction portion  90  is driven to suck the shaping material of the second flow path  152  into the cylinder  92 . The control unit  500  may adjust the rotation of the flat screw  40  without using the pressure value P measured by the pressure measuring portion  80  during a period when the plunger  93  of the suction portion  90  is driven to push the shaping material in the cylinder  92  out into the second flow path  152 . When the valve portion  73  is open, the pressure of the shaping material in the first flow path  151  tends to vary due to the driving of the plunger  93 . Therefore, the discharge of the shaping material from the nozzle hole  69  can be more reliably stabilized by adjusting the rotation speed of the flat screw  40  without using the pressure value P measured during the period when the plunger  93  is driven. 
     (D2) In the pressure adjusting processing of the embodiments described above, the control unit  500  may not use the moving average of the pressure values P acquired from the pressure measuring portion  80 . For example, in step S 225  shown in  FIG. 11 , the control unit  500  calculates the average pressure value Pave by dividing the total value (P 1 +P 2 +P 3 + . . . +P n ) from the first acquired pressure value P 1  to the n-th acquired pressure value P n  by the number of samples N from P 1  to P n , and adjusts the rotation speed of the flat screw  40  using the calculated average pressure value Pave. Thereafter, the control unit  500  may reset the stored values from the first acquired pressure value P 1  to the n-th acquired pressure value P n , calculate the average pressure value Pave by dividing a total value (P n+1 +P n+2 +P n+3 + . . . +P n+n ) from the (n+1)-th acquired pressure value P n+1  to an (n+n)-th acquired pressure value P n+n  by the number of samples N, and adjust the rotation speed of the flat screw  40  using the calculated average pressure value Pave. The control unit  500  may adjust the rotation speed of the flat screw  40  by using the pressure value P as it is without averaging the pressure values P acquired from the pressure measuring portion  80 . 
     (D3) In the pressure adjusting processing of the embodiments described above, when the average pressure value Pave exceeds the target pressure value Pb, the control unit  500  may decrease the rotation speed of the flat screw  40 , and when the average pressure value Pave falls below the target pressure value Pb, the control unit  500  may increase the rotation speed of the flat screw  40 . For example, by setting the pressure tolerance ΔP to 0, when the average pressure value Pave exceeds the target pressure value Pb, the control unit  500  can decrease the rotation speed of the flat screw  40 , and when the average pressure value Pave falls below the target pressure value Pb, the control unit  500  can increase the rotation speed of the flat screw  40 . In addition, by omitting the processing of step S 230  shown in  FIG. 11 , when the average pressure value Pave exceeds the target pressure value Pb, the control unit  500  can decrease the rotation speed of the flat screw  40 , and when the average pressure value Pave falls below the target pressure value Pb, the control unit  500  can increase the rotation speed of the flat screw  40 . When the pressure value P, instead of the average pressure value Pave, exceeds the target pressure value Pb, the control unit  500  may decrease the rotation speed of the flat screw  40 , and when the pressure value P falls below the target pressure value Pb, the control unit  500  may increase the rotation speed of the flat screw  40 . 
     (D4) In the pressure adjusting processing of the embodiments described above, in step S 230  of  FIG. 11 , when the average pressure value Pave is equal to or less than the first threshold value obtained by adding the pressure tolerance ΔP to the target pressure value Pb and is equal to or more than the second threshold value obtained by subtracting the pressure tolerance ΔP from the target pressure value Pb, the control unit  500  determines that the average pressure value Pave is within the allowable range. That is, the control unit  500  sets the first threshold value and the second threshold value such that an absolute value of a difference between the first threshold value and the target pressure value Pb is the same as an absolute value of a difference between the second threshold value and the target pressure value Pb. In contrast, the control unit  500  may set the first threshold value and the second threshold value such that the absolute value of the difference between the first threshold value and the target pressure value Pb is greater than the absolute value of the difference between the second threshold value and the target pressure value Pb, or may set the first threshold value and the second threshold value such that the absolute value of the difference between the first threshold value and the target pressure value Pb is smaller than the absolute value of the difference between the second threshold value and the target pressure value Pb. 
     (D5) In the pressure adjusting processing of the embodiments described above, when it is determined in step S 210  of  FIG. 11  that the valve portion  73  is not open, the control unit  500  does not adjust the rotation speed of the flat screw  40 . In contrast, when it is determined in step S 210  that the valve portion  73  is not open, the control unit  500  may adjust the rotation speed of the flat screw  40 . For example, in step S 205 , the control unit  500  acquires a first pressure tolerance ΔP 1  and a second pressure tolerance ΔP 2  greater than the first pressure tolerance ΔP 1 , and when it is determined in step S 210  that the valve portion  73  is open, the control unit  500  proceeds to step S 215 . Thereafter, in step S 230 , when the average pressure value Pave is equal to or less than a first threshold value obtained by adding the first pressure tolerance ΔP 1  to the target pressure value Pb and is equal to or more than a second threshold value obtained by subtracting the first pressure tolerance ΔP 1  from the target pressure value Pb, the control unit  500  determines that the average pressure value Pave is within the allowable range. On the other hand, when it is determined in step S 210  that the valve portion  73  is not open, the control unit  500  proceeds to step S 215 . Thereafter, in step S 230 , when the average pressure value Pave is equal to or less than a third threshold value obtained by adding the second pressure tolerance ΔP 2  to the target pressure value Pb and is equal to or more than a fourth threshold value obtained by subtracting the second pressure tolerance ΔP 2  from the target pressure value Pb, the control unit  500  determines that the average pressure value Pave is within the allowable range. A difference between the third threshold value and the fourth threshold value is greater than a difference between the first threshold value and the second threshold value. Therefore, in the example described above, when it is determined that the valve portion  73  is not open, the rotation speed of the flat screw  40  is less likely to be changed as compared with the case when it is determined that the valve portion  73  is open. That is, the degree of adjustment of the rotation of the flat screw  40  when it is determined that the valve portion  73  is not open can be made smaller than the degree of adjustment of the rotation of the flat screw  40  when it is determined that the valve portion  73  is open. In the example described above, the first pressure tolerance ΔP 1  may be set to 0, and the second pressure tolerance ΔP 2  may be set to a value greater than the first pressure tolerance ΔP 1 . 
     (D6) In the pressure adjusting processing of the embodiments described above, when it is determined in step S 210  of  FIG. 11  that the valve portion  73  is not open, the control unit  500  does not adjust the rotation speed of the flat screw  40 . In contrast, when it is determined in step S 210  that the valve portion  73  is not open, the control unit  500  may adjust the rotation speed of the flat screw  40 . For example, the control unit  500  acquires a first collection time T 1  and a second collection time T 2  longer than the first collection time T 1  in step S 205 , and proceeds to step S 215  when it is determined in step S 210  that the valve portion  73  is open. By repeating the processing from step S 210  to step S 220 , the control unit  500  acquires N samples of pressure values P within the first collection time T 1 . Thereafter, in step S 225 , the control unit  500  uses the N samples of pressure values P to calculate a first average pressure value Pave 1 . On the other hand, when it is determined in step S 210  that the valve portion  73  is not open, the control unit  500  proceeds to step S 215 . By repeating the processing from step S 210  to step S 220 , the control unit  500  acquires M samples of pressure values P within the second collection time T 2 , M being greater than N. Thereafter, in step S 225 , the control unit  500  uses the M samples of pressure values P to calculate a second average pressure value Pave 2 . By closing the valve portion  73 , even when the measured pressure values P gradually increase, the second average pressure value Pave 2  increases more slowly than the first average pressure value Pave 1 . Therefore, in the example described above, when it is determined that the valve portion  73  is not open, the rotation speed of the flat screw  40  is less likely to be changed as compared with the case when it is determined that the valve portion  73  is open. That is, the degree of adjustment of the rotation of the flat screw  40  when it is determined that the valve portion is not open can be made smaller than the degree of adjustment of the rotation of the flat screw  40  when it is determined that the valve portion  73  is open. 
     (D7) In the pressure adjusting processing of the second embodiment described above, the control unit  500  executes the pressure adjusting processing after the maintenance operation and before restarting the shaping of the three-dimensional shaped object, and does not execute the pressure adjusting processing during the period from when the shaping of the three-dimensional shaped object is restarted to when the shaping is paused. In contrast, the control unit  500  may execute the pressure adjusting processing also during the period from when the shaping of the three-dimensional shaped object is restarted to when the shaping is paused. 
     (D8) In the pressure adjusting processing of the embodiments described above, the control unit  500  may adjust the rotation speed of the flat screw  40  by a combination of a feedback control and a feedforward control. For example, the three-dimensional shaping devices  100 ,  100   b , and  100   c  may be provided with an outside temperature sensor, and the control unit  500  may use the feedforward control using an outside temperature acquired by the outside temperature sensor to adjust the rotation speed of the flat screw  40 . 
     (D9) In the three-dimensional shaping devices  100 ,  100   b , and  100   c  of the embodiments described above, the plasticization unit  30  includes the flat screw  40  having a flat columnar shape and the barrel  50  having the flat screw facing surface  52 . In contrast, the plasticization unit  30  may include an inline screw which has a long shaft-shaped outer shape and in which a spiral groove is formed on a side surface of a shaft, and a barrel having a cylindrical screw facing surface. 
     (D10) In the three-dimensional shaping devices  100 ,  100   b , and  100   c  of the embodiments described above, the drive unit  35  includes the drive motor  36  and a transmission, and the drive motor  36  may be coupled with the flat screw  40  via the transmission. In this case, the rotation speed of the flat screw  40  can be switched by switching a speed reduction ratio of the transmission. 
     (D11) In the three-dimensional shaping devices  100 ,  100   b , and  100   c  of the embodiments described above, a flow path member having a flow path communicating with the through hole  56  of the barrel  50  and the nozzle flow path  68  may be provided between the barrel  50  and the nozzle  61 . The cross hole  57  may be provided in the flow path member instead of the barrel  50 . In this case, the valve portion of the discharge amount adjusting mechanism  70  is disposed in the cross hole  57  provided in the flow path member. 
     (D12) In the three-dimensional shaping devices  100 ,  100   b , and  100   c  of the embodiments described above, the pressure measuring portion  80  may be provided in the second flow path  152 . In this case, the control unit  500  may use pressure of the shaping material in the second flow path  152  measured by the pressure measuring portion  80  to adjust the rotation speed of the flat screw  40 . 
     E. Other Aspects 
     The present disclosure is not limited to the above-described embodiments, and can be implemented in various aspects without departing from the spirit of the present disclosure. For example, the present disclosure can be implemented by the following aspects. In order to solve some or all of the problems described in the present disclosure, or to achieve some or all of the effects of the present disclosure, technical characteristics in the above embodiments corresponding to the technical characteristics in each of the embodiments described below can be appropriately replaced or combined. If the technical characteristics are not described as essential in the present description, they can be deleted as appropriate. 
     (1) According to a first aspect of the present disclosure, a three-dimensional shaping device is provided. The three-dimensional shaping device includes: a plasticization unit having a screw and configured to plasticize a material into a shaping material using the rotating screw; a drive unit configured to rotate the screw; a supply flow path communicating with the plasticization unit and through which the shaping material flows; a nozzle communicating with the supply flow path and configured to discharge the shaping material; a discharge amount adjusting mechanism having a valve portion provided in the supply flow path, and configured to switch between stop and restart of discharging of the shaping material from the nozzle by driving the valve portion; a pressure measuring portion configured to measure a pressure of the shaping material in the supply flow path between the plasticization unit and the valve portion; and a control unit configured to adjust rotation of the screw by controlling the drive unit according to a measured value of the pressure measured by the pressure measuring portion. The control unit controls the drive unit under a first control during a period when the discharging of the shaping material from the nozzle is not stopped by the discharge amount adjusting mechanism, and controls the drive unit under a second control during a period when the discharging of the shaping material from the nozzle is stopped by the discharge amount adjusting mechanism, and a degree of adjustment of the rotation of the screw under the second control is smaller than a degree of adjustment of the rotation of the screw under the first control. 
     According to the three-dimensional shaping device of this aspect, the control unit controls the drive unit under the first control with a large degree of adjustment of the rotation of the screw during the period when the discharge of the shaping material from the nozzle is not stopped by the discharge amount adjusting mechanism, and controls the drive unit under the second control with a small degree of adjustment of the rotation of the screw during the period when the discharge of the shaping material from the nozzle is stopped by the discharge amount adjusting mechanism. Therefore, during the period when the discharge of the shaping material from the nozzle is stopped, it is difficult to adjust the rotation of the screw even when the pressure of the shaping material varies, so that when the discharge of the shaping material from the nozzle is restarted, the unstable discharge of the shaping material from the nozzle can be prevented. 
     (2) In the three-dimensional shaping device of the above aspect, the control unit may change a rotation speed of the screw according to the measured value under the first control, and rotate the screw at a preset rotation speed under the second control. 
     According to the three-dimensional shaping device of this aspect, the degree of adjustment of the rotation of the screw under the second control can be made smaller than the degree of adjustment of the rotation of the screw under the first control. 
     (3) In the three-dimensional shaping device of the above aspect, the control unit may, under the first control, decrease the rotation of the screw when the measured value exceeds a target value of the pressure, and increase the rotation of the screw when the measured value falls below the target value. 
     According to the three-dimensional shaping device of this aspect, the measured value of the pressure of the shaping material under the first control can approach the target value. 
     (4) In the three-dimensional shaping device of the above aspect, the control unit may, under the first control, decrease the rotation of the screw when the measured value exceeds a first threshold value which is greater than a target value of the pressure, increase the rotation of the screw when the measured value falls below a second threshold value which is smaller than the target value, and not adjust the rotation of the screw when the measured value is equal to or less than the first threshold value and equal to or more than the second threshold value. 
     According to the three-dimensional shaping device of this aspect, when a pressure value exceeds the first threshold value or falls below the second threshold value, the control unit adjusts the rotation of the screw. Therefore, it is possible to prevent the unstable discharge of the shaping material from the nozzle with the adjustment on the rotation of the screw being repeated due to a small variation in the pressure. 
     (5) In the three-dimensional shaping device of the above aspect, under the first control, the control unit may calculate a moving average value of the pressure using a plurality of measured values, and adjust the rotation of the screw by controlling the drive unit according to the moving average value. 
     According to the three-dimensional shaping device of this aspect, since the control unit adjusts the rotation of the screw by using the moving average value of the pressure of the shaping material, it is possible to prevent the rotation of the screw from becoming unstable due to a sudden variation in pressure. Therefore, the unstable discharge of the shaping material from the nozzle can be further prevented. 
     (6) In the three-dimensional shaping device of the above aspect, the screw of the plasticization unit may be a flat screw having a groove forming surface on which a groove through which the material is supplied is formed, and the plasticization unit may include a barrel having a facing surface which faces the groove forming surface, with an opening portion of the supply flow path being provided on the facing surface, and plasticize the material between the flat screw and the barrel into the shaping material, such that the shaping material flows from the opening portion into the supply flow path. 
     According to the three-dimensional shaping device of this aspect, since the material can be plasticized using a small flat screw, it is possible to reduce a size of the three-dimensional shaping device. 
     (7) In the three-dimensional shaping device of the above aspect, the valve portion may have a recessed portion configured to communicate with the plasticization unit and the nozzle, and the discharge amount adjusting mechanism may rotate the valve portion about a rotation shaft intersecting a direction from the plasticization unit toward the nozzle to change a position of the recessed portion, so that a flow path cross-sectional area of the supply flow path is changed to adjust a flow rate of the shaping material to be supplied to the nozzle. 
     According to the three-dimensional shaping device of this aspect, switching between the stop and restart of the discharge of the shaping material from the nozzle can be implemented with a simple configuration. 
     (8) In the three-dimensional shaping device of the above aspect, a suction portion configured to suck the shaping material is coupled to the supply flow path between the valve portion and the nozzle, and the control unit may adjust, under the first control, the rotation of the screw by controlling the drive unit without using the measured value which is measured during a period when the shaping material is sucked by the suction portion. 
     According to the three-dimensional shaping device of this aspect, stringing of the shaping material from the nozzle can be prevented by sucking the shaping material of the supply flow path between the valve portion and the nozzle using the suction portion, and the rotation of the screw is adjusted without using the pressure value of the shaping material measured during the period when the shaping material is sucked by the suction portion, so that it is possible to prevent the rotation of the screw from becoming unstable. 
     (9) In the three-dimensional shaping device of the above aspect, the control unit may adjust, under the first control, the rotation of the screw by controlling the drive unit referring to a table in which a relationship between a rotation speed of the screw and the measured value is expressed. 
     According to the three-dimensional shaping device of this aspect, even when the relationship between the rotation speed of the screw and the pressure of the shaping material is non-linear, the discharge of the shaping material from the nozzle can be stabilized. 
     (10) The three-dimensional shaping device of the above aspect further includes a heating portion configured to heat the shaping material of the supply flow path between the valve portion and the nozzle, in which the control unit may adjust, under at least one of the first control and the second control, a temperature of the heating portion according to the measured value. 
     According to the three-dimensional shaping device of this aspect, fluidity of the shaping material discharged from the nozzle can be adjusted by adjusting the temperature of the heating portion by the control unit. Therefore, the discharge of the shaping material from the nozzle can be further stabilized. 
     (11) In the three-dimensional shaping device of the above aspect, the control unit may control the drive unit under a third control during a period after a maintenance operation of the three-dimensional shaping device and before starting shaping a three-dimensional shaped object, among a period when the discharge of the shaping material from the nozzle is not stopped by the discharge amount adjusting mechanism, and the degree of adjustment of the rotation of the screw under the first control may be smaller than a degree of adjustment of the rotation of the screw under the third control. 
     According to the three-dimensional shaping device of this aspect, the control unit adjusts the rotation of the screw in advance during the period after the maintenance operation and before starting shaping a three-dimensional shaped object, and then starts shaping the three-dimensional shaped object. Therefore, the discharge of the shaping material from the nozzle can be stabilized. 
     (12) In the three-dimensional shaping device of the above aspect, the control unit may, under the first control, decrease the rotation of the screw when the measured value exceeds a first threshold value which is greater than a target value of the pressure, and increase the rotation of the screw when the measured value falls below a second threshold value which is smaller than the target value, and under the second control, decrease the rotation of the screw when the measured value exceeds a third threshold value which is greater than the target value, and increase the rotation of the screw when the measured value falls below a fourth threshold value which is smaller than the target value, and a difference between the third threshold value and the fourth threshold value is greater than a difference between the first threshold value and the second threshold value. 
     According to the three-dimensional shaping device of this aspect, the adjustment of the rotation of the screw under the first control is less likely to be started as compared with that under the second control. Therefore, the degree of adjustment of the rotation of the screw under the second control can be made smaller than the degree of adjustment of the rotation of the screw under the first control. 
     (13) In the three-dimensional shaping device of the above aspect, the control unit may, under the first control, decrease the rotation of the screw when the measured value exceeds a target value of the pressure, and increase the rotation of the screw when the measured value falls below the target value, and under the second control, decrease the rotation of the screw when the measured value exceeds a third threshold value which is greater than the target value, and increase the rotation of the screw when the measured value falls below a fourth threshold value which is smaller than the target value. 
     According to the three-dimensional shaping device of this aspect, the adjustment of the rotation of the screw under the first control is less likely to be started as compared with that under the second control. Therefore, the degree of adjustment of the rotation of the screw under the second control can be made smaller than the degree of adjustment of the rotation of the screw under the first control. 
     (14) In the three-dimensional shaping device of the above aspect, under the first control and the second control, the control unit may calculate a moving average value of the pressure using a plurality of measured values, and adjust the rotation of the screw by controlling the drive unit according to the moving average value, and the number of samples of measured values used to calculate the moving average value under the second control is larger than the number of samples of measured values used to calculate the moving average value under the first control. 
     According to the three-dimensional shaping device of this aspect, the adjustment of the rotation of the screw under the first control is less likely to be started as compared with that under the second control. Therefore, the degree of adjustment of the rotation of the screw under the second control can be made smaller than the degree of adjustment of the rotation of the screw under the first control. 
     The present disclosure may be implemented in various forms other than the three-dimensional shaping device. For example, the present disclosure may be implemented in forms such as a method for controlling a three-dimensional shaping device and a method for manufacturing a three-dimensional shaped object.