Stereolithography system and stereolithography method

Abstract

To provide a three-dimensional molding system and a three-dimensional molding method capable of stabilizing the discharge amount of a cement-based material.SOLUTION: A three-dimensional molding system 100A forms a three-dimensional molded object by laminating a cement-based material C and comprises: a nozzle 13 discharging the cement-based material C; a screw discharging the cement-based material C from the nozzle 13 by rotation; a detection device 6 detecting information correlated with the discharge amount of the nozzle 13; and a control device 5 adjusting the rotary speed of the screw so that the discharge amount of the nozzle 13 is made certain based on the detection result of the detection device 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a three-dimensional modeling system and a three-dimensional modeling method.

Background Art

[0002] In recent years, various techniques have been proposed for forming shaped objects such as buildings and structures using cement-based materials such as concrete and mortar by applying 3D printer technology (see, for example, Patent Documents 1 and 2). As an example of forming this type of shaped object using 3D printer technology, first, the three-dimensional shape of the shaped object to be formed is modeled by a computer. Next, two-dimensional data divided into a large number of layers is generated from the modeled three-dimensional data. Then, a cement-based material is supplied from a pump to a movable supply head, and based on the two-dimensional data of each layer, the cement-based material is discharged from the nozzle of the supply head to form the two-dimensional shape of each layer. Then, based on the two-dimensional data of the subsequent layer, the cement-based material is laminated layer by layer on the formed two-dimensional shaped layer, thereby forming a three-dimensional shaped object.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In 3D printers for construction use, cementitious materials such as mortar and concrete are used, but the fluidity of these materials changes over time due to various factors. For example, the effect of admixtures for maintaining fluidity varies depending on environmental factors such as temperature and humidity, and the degree of change in fluidity also varies. In addition, depending on the type of admixture used, the fluidity may increase over time, and it is not always the case that the fluidity decreases over time. Thus, it is difficult to predict and correct the temporal change in fluidity in advance. Therefore, the discharge amount is not stable, resulting in a decrease in lamination accuracy and disturbance, and it may lead to the collapse of the shaped object. From such a perspective, the present invention provides a three-dimensional shaping system and a three-dimensional shaping method capable of stabilizing the discharge amount of a cementitious material.

Means for Solving the Problems

[0005] The three-dimensional shaping system according to the present invention is a three-dimensional shaping system that forms a three-dimensional shaped object by laminating a cementitious material. This three-dimensional shaping system includes a nozzle that discharges the cementitious material, a screw that rotates to discharge the cementitious material from the nozzle, a detection device that detects information correlated with the discharge amount of the nozzle, and a control device. The control device adjusts the rotation speed of the screw so that the discharge amount of the nozzle becomes constant based on the detection result of the detection device. In the three-dimensional shaping system according to the present invention, since the discharge amount is adjusted while grasping the change in the discharge amount in real time, the discharge amount of the cementitious material can be stabilized. As a result, it is possible to form a shaped object with high precision. The control device may include a first control device that outputs a control signal for controlling the rotational speed of the motor that drives the screw, and a second control device that corrects the control signal by feedback control. In that case, the first control device has information indicating the relationship between the moving speed of the nozzle and the rotational speed of the screw, and outputs a first pulse signal corresponding to the moving speed of the nozzle. The second control device adjusts the period of the first pulse signal based on the detection result of the detection device, and outputs the adjusted second pulse signal to the motor. The second control device adjusts the period of the first pulse signal by, for example, PI control.

[0006] The detection device may be a load cell that measures the weight of the nozzle, and may detect a decrease in the weight of the nozzle as information correlated with the discharge amount of the nozzle. In that case, it may further include a supply device that supplies the cement-based material to the nozzle, and the control device may keep the rotational speed of the screw constant without changing it during the period when the cement-based material is supplied by the supply device. Also, the detection device may be a load cell that measures the weight of the table on which the shaped object is formed, and may detect an increase in the weight of the table as information correlated with the discharge amount of the nozzle. Also, the detection device may be a sensor that detects the flow rate of the cement-based material discharged from the nozzle, or image analysis means that calculates the flow rate of the cement-based material discharged by analyzing an image of the cement-based material discharged from the nozzle.

[0007] The three-dimensional shaping method according to the present invention is a three-dimensional shaping method in which a cement-based material is laminated to form a three-dimensional shaped object, and the shaped object is formed by rotating a screw to discharge the cement-based material from a nozzle. This three-dimensional modeling method includes a detection step of detecting information correlated with the discharge amount of the nozzle, and a control step of adjusting the rotational speed of the screw based on the detection result of the detection step so that the discharge amount of the nozzle becomes constant. The detection step and the control step are repeatedly executed. In the three-dimensional modeling method according to the present invention, since the discharge amount is adjusted while grasping the change in the discharge amount in real time, the discharge amount of the cement-based material can be stabilized. As a result, it is possible to form a highly accurate molded object.

Effect of the Invention

[0008] According to the present invention, the discharge amount of the cement-based material can be stabilized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. In the drawings shown below, the same or similar members are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. In addition, the sizes and shapes of the members may be schematically represented in a deformed or exaggerated manner for the convenience of explanation.

[0011] [First Embodiment] <Configuration of the three-dimensional modeling system according to the first embodiment> With reference to FIGS. 1 and 2, the configuration of the three-dimensional modeling system 100A according to the first embodiment will be described. FIG. 1 is a perspective view showing an overview of the three-dimensional modeling system 100A according to the first embodiment of the present invention. FIG. 2 is a front view showing an overview of the three-dimensional modeling system 100A according to the first embodiment of the present invention. In FIG. 1, a part of the elements constituting the nozzle device 1 is omitted. The three-dimensional modeling system 100A is a so-called 3D printer that forms a three-dimensional object by generating a two-dimensional shape while extruding a cement-based material from the nozzle device 1 and laminating it in the height direction. The cement-based material is a hydraulic composition (which may not contain cement) that hardens by a hydration reaction, such as concrete, mortar, cement paste, etc. The three-dimensional modeling system 100A according to the first embodiment assumes a relatively small 3D printer. Note that the three-dimensional modeling system 100B (see FIG. 9) according to the second embodiment described later assumes a relatively large 3D printer.

[0012] As shown in FIG. 1, the three-dimensional modeling system 100A mainly includes a nozzle device 1, a nozzle support device 2, a table device 3, a supply device 4, and a control device 5. The nozzle device 1 is a device for forming a shaped object on the table device 3. The nozzle device 1 has a nozzle 13 at its tip (lower end) for discharging a cement-based material C. The nozzle device 1 moves in a plane while discharging the cement-based material C from the nozzle 13. When the nozzle device 1 forms a predetermined two-dimensional shape by planar movement, the forming surface 3a of the table device 3 moves downward. That is, the nozzle device 1 is supported by the nozzle support device 2 so as to be movable two-dimensionally on the XY plane of FIG. 1. Note that the nozzle device 1 may be supported by the nozzle support device 2 so as to be movable three-dimensionally. The nozzle device 1 is connected to the control device 5 and discharges the cement-based material C in response to a signal from the control device 5.

[0013] The nozzle support device 2 shown in FIG. 1 is a device that supports the nozzle device 1. The nozzle support device 2 moves the nozzle device 1 in a plane along the X-axis and the Y-axis. The nozzle support device 2 of the present embodiment includes an X-axis rail 21 disposed along the X-axis, a pair of Y-axis rails 22 disposed along the Y-axis, and a Z-axis column 23 erected along the Z-axis. The X-axis rail 21 slidably supports the nozzle device 1. The nozzle device 1 moves in the X-axis direction by moving along the X-axis rail 21. Further, the X-axis rail 21 is horizontally and slidably mounted on the pair of Y-axis rails 22. When the X-axis rail 21 slides along the Y-axis rail 22, the nozzle device 1 moves in the Y-axis direction. Further, when the nozzle device 1 moves along the X-axis rail 21 and at the same time the X-axis rail 21 moves along the Y-axis rail 22, the nozzle device 1 moves in an oblique direction. That is, the X-axis rail 21 and the Y-axis rail 22 enable the nozzle device 1 to move freely in a plane. The nozzle support device 2 is connected to the control device 5 and moves the nozzle device 1 in a predetermined direction in response to a signal transmitted from the control device 5.

[0014] The table device 3 shown in FIG. 1 is the part where the shaped object is formed. The table device 3 can move up and down along the Z-axis on the forming surface 3a where the shaped object is formed. That is, the three-dimensional shaping system 100 can move the nozzle device 1 two-dimensionally on the XY plane via the nozzle support device 2, and can form a three-dimensional shaped object by moving the table device 3 up and down along the Z-axis on the forming surface 3a. As shown in FIG. 2, the table device 3 of this embodiment includes a production table 32 having a forming surface 3a, a column frame 33 erected along the Z-axis, and a height adjustment mechanism (not shown) for adjusting the height of the production table 32 via the column frame 33. The production table 32 is in a flat plate shape and has the forming surface 3a on its upper surface. The production table 32 and the column frame 33 move up and down by the height adjustment mechanism. The table device 3 is connected to the control device 5 and moves the production table 32 in the vertical direction (downward when forming the shaped object) in response to a signal transmitted from the control device 5.

[0015] The supply device 4 is a device that supplies the cement-based material C to the nozzle device 1. The supply device 4 mainly includes a hopper 41 as a storage part, a pump 42 as a drive source, and a supply pipe 43. The cement-based material C kneaded and mixed in a predetermined composition is stored in the hopper 41. The supply pipe 43 connects the hopper 41 and the nozzle device 1. The pump 42 is installed in the supply pipe 43, and when the pump 42 operates, the cement-based material C stored in the hopper 41 is supplied to the nozzle device 1. The pump 42 is connected to the control device 5 and supplies the cement-based material C to the nozzle device 1 in response to a signal transmitted from the control device 5.

[0016] As shown in FIG. 1, the control device 5 is a device that controls the overall operation of the three-dimensional modeling system 100A. The control device 5 can be composed of one or more devices. The control device 5 stores two-dimensional data for each layer obtained from the three-dimensional shape data. Various codes (instructions) such as G-code are described in this two-dimensional data. The control device 5 transmits control signals to the nozzle support device 2 and the table device 3 based on the two-dimensional data for each layer, and moves the nozzle device 1 with respect to the forming surface 3a. Further, the control device 5 controls the nozzle device 1 so that the discharge amount from the nozzle 13 becomes constant. The control device 5 controls the discharge amount of the nozzle 13 to be constant by feedback control based on the discharge amount of the nozzle 13. In addition, the control device 5 controls the supply device 4 to supply the cement-based material C to the nozzle device 1 at a predetermined timing. Hereinafter, the configuration related to the feedback control of the discharge amount will be described.

[0017] (Configuration related to feedback control of discharge amount) First, referring to FIG. 3, the internal structure of the nozzle device 1 will be described. FIG. 3 is an enlarged cross-sectional view of the nozzle device 1. As shown in FIG. 3, the nozzle device 1 includes a cylinder portion 11 having the vertical direction as the central axis direction, a screw conveyance portion 12 in which a screw 14 is accommodated, and a nozzle 13 detachably attached to the tip of the screw conveyance portion 12. An upper portion in the cylinder portion 11 is provided with a storage chamber 11a. The storage chamber 11a is formed in a substantially hollow cylindrical shape with a large diameter at the upper portion, and its lower portion is formed in a hollow substantially inverted frustum shape whose diameter decreases downward. Further, a connecting portion with the lower screw conveyance portion 12 is formed in a hollow cylindrical shape with a small diameter. The screw conveyance portion 12 is formed in a cylindrical shape having substantially the same inner diameter as the small-diameter portion at the lower part of the cylinder portion 11. The nozzle 13 has a funnel shape, and a discharge port 13a is provided downward at its tip. A supply pipe 43 is connected to the cylinder portion 11. A drive motor 15 is provided above the nozzle device 1. A rotary shaft 16 is connected to the output shaft of the drive motor 15 via a coupling (not shown). The rotational driving force of the drive motor 15 is transmitted to the rotary shaft 16. A stirring blade 17, which is a stirring member formed by combining a helical wire, is attached to the rotary shaft 16 at a position within the storage chamber 11a of the cylinder portion 11. At the lower end of the rotary shaft 16, a screw 14 having a helical male thread portion formed on its outer peripheral surface is fixed in a posture of hanging coaxially with the rotary shaft 16. When the screw 14 rotates at an arbitrary steady speed by the forward rotation drive of the drive motor 15, the cementitious material C in the storage chamber 11a is pushed out toward the tip of the nozzle 13 by the helical male thread portion. Thereby, the cementitious material C in the cylinder portion 11 can be quantitatively pressure-fed toward the tip of the screw conveyor 12.

[0018] As shown in FIGS. 1 and 2, the three-dimensional modeling system 100A includes a detection device 6 in addition to the components described so far. The detection device 6 is a device that detects information correlated with the discharge amount of the nozzle 13. The information detected by the detection device 6 is sent to the control device 5 and used for feedback control to adjust the discharge amount of the nozzle 13. The configuration of the detection device 6, the type and number of physical quantities to be detected, etc. are not particularly limited, and any device can be used as long as it can appropriately detect information correlated with the discharge amount of the nozzle 13. The information correlated with the discharge amount of the nozzle 13 may be, for example, the weight, volume, flow rate, etc. of the discharged cementitious material C. The detection device 6 of the present embodiment is attached to the nozzle device 1 and measures the weight of the nozzle device 1. The detection device 6 is a beam type load cell and supports the nozzle device 1 from both sides. That is, one end of the detection device 6 (the side fixed to the immovable body) is fixed to an X-axis slide mechanism 19 (see FIG. 2) that enables movement along the X-axis rail 21 of the nozzle support device 2, and the other end of the detection device 6 (the side for measuring the load) supports the lower plate 18a of a frame portion 18 (see FIG. 2) attached to the cylinder portion 11.

[0019] As shown in FIG. 2, the X-axis slide mechanism 19 mainly includes a ball screw 19a and a slide portion 19b. The ball screw 19a is a component that converts rotational motion into linear motion and is connected to a drive source (not shown). When the rotational driving force generated by the drive source (not shown) is transmitted to the ball screw 19a, the slide portion 19b moves in the X-axis direction, and the nozzle device 1 integrated with the slide portion 19b also moves in the X-axis direction. As shown in FIG. 1, one end of the detection device 6 is fixed to the slide portion 19b with a screw. The frame portion 18 shown in FIG. 2 plays a role in reinforcing the nozzle device 1 and is attached so as to surround the cylinder portion 11. The frame portion 18 mainly includes a lower plate 18a disposed at the lower part of the cylinder portion 11, an upper plate 18b disposed at the upper part of the cylinder portion 11, and a motor plate 18c used for fixing the drive motor 15. Further, the frame portion 18 includes a Z-axis frame 18d connecting the lower plate 18a and the upper plate 18b, and a Z-axis frame 18e connecting the upper plate 18b and the motor plate 18c. As shown in FIG. 1, the other end of the detection device 6 supports the lower plate 18a from below. Thus, the load of the nozzle device 1 is applied to the two detection devices 6.

[0020] Also, as shown in FIG. 1, the X-axis slide mechanism 19 (see FIG. 2) includes a rear plate 19c disposed upward from the rear portion of the slide portion 19b. As shown in FIG. 2, a pair of linear bushings 19d are installed at the upper part of the rear plate 19c. A linear shaft 18g fixed to the upper plate 18b is inserted through the linear bushings 19d. The linear shaft 18g is fixed via a shaft holder 18f provided on the lower surface of the upper plate 18b and is disposed along the Z-axis. By the linear shaft 18g and the linear bushings 19d, the load detected by the detection device 6 is limited to the load in the Z-axis direction (vertical load).

[0021] Next, with reference to FIG. 4, the configuration of the control device 5 and its peripheral devices will be described. FIG. 4 is a diagram showing the configuration of the control device 5 and its peripheral devices included in the three-dimensional modeling system 100A according to the first embodiment of the present invention. Note that the description will focus on the feedback control of the discharge amount related to the present invention, and detailed description of the general control of the 3D printer will be omitted. As shown in FIG. 4, the control device 5 mainly includes two computers 51a and 51b, a 3D printer controller 52, and two motor controllers 54a and 54b. The control device 5 has a function of controlling the position of the nozzle device 1 in the X, Y, and Z axes and a function of controlling the discharge amount of the cement-based material C. In FIG. 4, the components necessary for the function of controlling the position of the nozzle device 1 are collectively described as "control device 5a", and the components necessary for the function of controlling the discharge amount of the cement-based material C are collectively described as "control device 5b". Regarding the position control of the nozzle device 1, in the present embodiment, the manufacturing table 32 of the table device 3 is moved up and down to relatively change the position of the nozzle device 1 in the Z-axis direction with respect to the forming surface 3a.

[0022] The control device 5a mainly consists of a computer 51a, a 3D printer controller 52, and a motor controller 54a. The computer 51a is operated by the manufacturer of the object to be fabricated and receives the input of information related to the fabrication of the object (such as an instruction to start fabrication). The computer 51a has, for example, a control panel operated by the manufacturer. The 3D printer controller 52 controls the entire stereolithography system 100A. The 3D printer controller 52 outputs, for example, the position information of the nozzle device 1 and the fabrication table 32 (which may be information on the amount of movement) to the motor controller 54a. The motor controller 54a controls the position of the nozzle device 1 on the X, Y, and Z axes. Based on the position information received from the 3D printer controller 52, the motor controller 54a creates a control signal for realizing the movement of the X, Y, and Z axes and drives a drive motor (not shown) via the motor driver 61a. Thereby, the nozzle device 1 is moved planar along the X and Y axes, and the fabrication table 32 is moved up and down along the Z axis.

[0023] The control device 5b mainly consists of a computer 51b, a 3D printer controller 52, and a motor controller 54b. The computer 51b is used, for example, for issuing commands for feedback control described later and for monitoring the discharge amount of the cement-based material C. The computer 51b can be replaced, for example, with a microcomputer. The 3D printer controller 52 controls the nozzle device 1 to discharge the cement-based material C from the nozzle 13. Specifically, the 3D printer controller 52 outputs a control signal for controlling the rotation speed of the drive motor 15 that drives the screw 14 to the motor controller 54b. The 3D printer controller 52 has, for example, information indicating the relationship between the movement speed of the nozzle device 1 and the rotation speed of the screw 14 in advance and outputs a control signal corresponding to the movement speed of the nozzle device 1. Note that the 3D printer controller 52 is an example of the "first control device" in the claims, and the motor controller 54b is an example of the "second control device" in the claims. The motor controller 54b adjusts the drive motor 15 (i.e., the rotation speed of the screw 14) so that the discharge amount from the nozzle 13 becomes constant. A control signal for the drive motor 15 is input to the motor controller 54b from the 3D printer controller 52. Further, a detection result (information correlated with the discharge amount from the nozzle 13) is input to the motor controller 54b from the detection device 6 via the indicator 62. In the present embodiment, it is assumed that, as information correlated with the discharge amount, the weight of the nozzle device 1 is input to the motor controller 54b at a constant cycle (which may be a variable cycle). The motor controller 54b adjusts the control signal for the drive motor 15 output from the 3D printer controller 52 by feedback control using the input information. The motor controller 54b drives the drive motor 15 with the adjusted control signal via the motor driver 61b. Note that the timing for performing the feedback control is not particularly limited.

[0024] With reference to FIGS. 5 and 6, the function of the motor controller 54b will be described more specifically. FIG. 5 is an illustration of a circuit diagram and a control program of the motor controller 54b. FIG. 6 is a diagram for explaining the PI control of the motor controller 54b. Note that the PI control is an example of feedback control, and other control may be used as the feedback control. As shown in FIG. 5, the motor controller 54b receives a pulse signal for motor control output from the 3D printer controller 52 and counts the total number of pulses according to the forward and reverse rotations (discharge command detection function). Further, the motor controller 54b receives a load value from the detection device 6 via the indicator 62 at a constant cycle (variable) and converts it into numerical data (discharge amount detection function). Also, as shown in FIG. 6, the motor controller 54b multiplies the pulse change amount Δp of the discharge command by the discharge rate k to obtain a target weight change amount Δr. When Δp exceeds the specified pulse increase amount, based on the error e with the discharge weight change amount Δd, the motor rotation speed coefficient m is calculated within the upper and lower limits by PI control (Kp, Ki) (PI control function). This is executed for each specified pulse change amount Δp. Further, the motor controller 54b outputs a pulse period signal obtained by multiplying the period measurement value of the pulse signal for motor control by the motor rotation speed coefficient m of the PI control output (motor control function). That is, the motor controller 54b variably controls the motor rotation with respect to the commanded speed from the 3D printer controller 52.

[0025] With reference to FIG. 7, the control of the motor controller 54b will be described. FIG. 7 is a flowchart showing an example of the control of the motor controller 54b. The motor controller 54b starts the process shown in FIG. 7 when the formation of the shaped object is started and the reception of the control signal of the drive motor 15 from the 3D printer controller 52 is started. The motor controller 54b acquires the detection result of the detection device 6 (here, the weight of the nozzle device 1 including the cement-based material C to be accommodated) (step S10). The motor controller 54b calculates the amount of decrease in the weight of the nozzle device 1 from the comparison with the previous detection result, and specifies the discharge amount of the cement-based material C from the amount of decrease in the weight. Next, the motor controller 54b adjusts the control signal of the drive motor 15 (that is, the rotation speed of the screw 14) so that the discharge amount of the nozzle 13 becomes constant based on the specified discharge amount of the cement-based material C (step S20). Specifically, the motor controller 54b compares the discharge amount with the assumed value, and determines whether the discharge amount is less than (or greater than) the assumed value (step S21). When the discharge amount is less than the assumed value, the motor controller 54b performs a process of adjusting the control signal to increase the rotation speed of the drive motor 15 (a process of shortening the period of the control signal) (step S22). When the discharge amount is greater than the assumed value, the motor controller 54b performs a process of adjusting the control signal to decrease the rotation speed of the drive motor 15 (a process of lengthening the period of the control signal) (step S23). In the present embodiment, PI control is assumed, and a control signal (motor rotation speed coefficient m) that is proportional to the deviation between the discharge amount and the assumed value (P control) and further proportional to the accumulated amount of past deviations (I control) is calculated. The adjusted control signal is transmitted to the drive motor 15, and the drive motor 15 is driven based on the adjusted control signal.

[0026] The processes of steps S10 and S20 are repeatedly executed until the formation of the shaped object is completed (step S30). Note that the process of step S30 is exited at the timing when the supply device 4 starts supplying the cementitious material C to the nozzle device 1, and during the period when the cementitious material C is being supplied, it is preferable not to perform feedback control using the detection device 6. This is because it becomes difficult to calculate the amount of weight reduction of the nozzle device 1 from the detection result of the detection device 6. The supply of the cementitious material C ends when the height of the cementitious material C in the storage chamber 11a of the cylinder unit 11 reaches a certain height or more. For example, a sensor (not shown) detects the amount of the cementitious material C in the storage chamber 11a and notifies the supply device 4 of this. The motor controller 54b resumes feedback control using the detection device 6 after the supply of the cementitious material C by the supply device 4 ends. The control during the period when the cementitious material C is being supplied may, for example, continue with the previous control state. Note that even during the period when the cementitious material C is being supplied, the discharge amount is specified in consideration of the supply amount of the cementitious material C (for example, a value obtained by adding the supply amount to the amount of weight reduction of the nozzle device 1 is used as the discharge amount), and a process of increasing (or decreasing) the rotational speed of the drive motor 15 may be executed using the specified discharge amount.

[0027] As described above, in the three-dimensional shaping system 100A according to the first embodiment, even if the fluidity of the cementitious material C changes due to environmental factors such as the passage of time and temperature changes, the discharge amount from the nozzle 13 always remains constant and stable. As a result, it is possible to prevent a decrease in lamination accuracy, disturbance, and collapse of the shaped object.

[0028] [Modification Example of the First Embodiment] As shown in FIGS. 1 and 2, in the first embodiment, the weight of the nozzle device 1 is measured by the detection device 6. However, as shown in FIG. 8, instead of and / or together with the detection device 6, a detection device 7 for measuring the weight of the production table 31 having the formation surface 3a may be installed. The table device 3 shown in Fig. 8 includes a production table 31 having a forming surface 3a, a lower frame 35 disposed below the production table 31, a column frame 33 erected along the Z axis, a height adjustment mechanism (not shown) for adjusting the height of the production table 31 via the lower frame 35 and the column frame 33, and a detection device 7 for measuring the weight of the production table 31. The production table 31 is in a flat plate shape and has the forming surface 3a on its upper surface. A table level adjustment screw 34 for leveling the forming surface 3a is provided on the lower surface side near the corners of the production table 31, and by rotating the table level adjustment screw 34 clockwise or counterclockwise, the vertical position of the production table 31 can be partially adjusted. The detection device 7 shown in Fig. 8 is, for example, a beam type load cell and is disposed between the production table 31 of the nozzle support device 2 and the lower frame 35. The detection device 7 holds the production table 31 in a state of being lifted from the lower frame 35. When this detection device 7 is used, the motor controller 54b acquires the detection result of the detection device 7 (here, the weight of the production table 31 including the workpiece formed on the forming surface 3a). The motor controller 54b calculates the increase amount of the production table 31 from the comparison with the previous detection result, and specifies the discharge amount of the cementitious material C from the increase amount of the weight. Even when this detection device 7 is used, as in the first embodiment, even if the fluidity of the cementitious material C changes due to environmental factors such as the passage of time and temperature changes, the discharge amount from the nozzle 13 can always be made constant. Further, by using the detection device 7, feedback control during the period when the cementitious material C is being supplied becomes possible.

[0029] [Second Embodiment] [Configuration of the Three-Dimensional Modeling System According to the Second Embodiment]< With reference to Fig. 9 (and appropriately referring to Fig. 1), the configuration of the three-dimensional modeling system 100B according to the second embodiment will be described. Fig. 9 is a front view showing an overview of the three-dimensional modeling system 100B according to the second embodiment of the present invention. As described above, the three-dimensional modeling system 100B according to the second embodiment assumes a relatively large 3D printer. The three-dimensional modeling system 100B forms a three-dimensional object by extruding a cement-based material C from a nozzle device 101 to generate a two-dimensional shape and stacking it in the height direction, and is a so-called 3D printer. The cement-based material C is a hydraulic composition (which may not contain cement) that hardens by a hydration reaction, such as concrete, mortar, cement paste, etc. Hereinafter, the description will focus on the differences from the first embodiment.

[0030] As shown in FIG. 9, the three-dimensional modeling system 100B mainly includes a nozzle device 101, a nozzle support device 102, a production table 103, a supply device 4 (see FIG. 1), and a control device 5 (see FIG. 1). The nozzle device 101 is a device for forming an object on the production table 103. The nozzle device 101 has a nozzle 113 for discharging the cement-based material C at its tip (lower end). The nozzle device 101 moves horizontally while discharging the cement-based material C from the nozzle 113. When the nozzle device 101 forms a predetermined two-dimensional shape by horizontal movement, it moves upward. That is, the nozzle device 101 is supported by the nozzle support device 102 so as to be movable three-dimensionally. The nozzle device 101 is connected to the control device 5 and discharges the cement-based material C according to a signal from the control device 5. The production table 103 is a part where the object is formed. The production table 103 includes a forming surface 103a on which the object is formed. The production table 103 is fixed to the floor surface, and the forming surface 103a of the present embodiment does not move up and down.

[0031] The nozzle support device 102 shown in FIG. 9 is a device that supports the nozzle device 101. The nozzle support device 102 moves the nozzle device 101 in a plane along the X-axis and the Y-axis, and moves it up and down along the Z-axis. That is, the three-dimensional modeling system 100B can form a three-dimensional modeled object by moving the nozzle device 101 three-dimensionally via the nozzle support device 102. The nozzle support device 102 of the present embodiment includes an X-axis rail 121 disposed along the X-axis, a pair of Y-axis rails 122 disposed along the Y-axis, a Z-axis column 123 erected along the Z-axis, and a hoisting mechanism 124 that holds a Z-axis slide portion 119 that moves in the Z-axis direction together with the nozzle support device 102 and fixes the position of the nozzle support device 102 in the Z-axis direction. The hoisting mechanism 124 is slidably installed on the X-axis rail 121. When the hoisting mechanism 124 slides along the X-axis rail 121, the nozzle device 101 moves in the X-axis direction. Further, the X-axis rail 121 is horizontally and slidably mounted on the pair of Y-axis rails 122. When the X-axis rail 121 slides along the Y-axis rail 122, the nozzle device 101 moves in the Y-axis direction. Also, when the hoisting mechanism 124 moves along the X-axis rail 121 and at the same time the X-axis rail 121 moves along the Y-axis rail 122, the nozzle device 101 moves in an oblique direction. That is, the X-axis rail 121 and the Y-axis rail 122 enable the nozzle device 101 to move freely in a plane. Furthermore, the hoisting mechanism 124 slidably supports the Z-axis slide portion 119 to which the nozzle device 101 is fixed. The Z-axis slide portion 119 has a Z-axis frame 119a disposed along the Z-axis, and the nozzle device 101 moves up and down by changing the position where the hoisting mechanism 124 holds the Z-axis frame 119a. The nozzle support device 102 is connected to the control device 5, and moves the nozzle device 101 in a predetermined direction in response to a signal transmitted from the control device 5.

[0032] Referring to FIG. 10, the structure of the nozzle device 101 will be described. FIG. 10 is an enlarged front view of the nozzle device 101. The basic structure of the nozzle device 101 is the same as that of the nozzle device 1 in the first embodiment. As shown in FIG. 10, the nozzle device 101 includes a cylinder portion 111 with the vertical direction as the central axis direction, a screw conveying portion 112 in which a screw 114 is accommodated, and a nozzle 113 detachably attached to the tip of the screw conveying portion 112. The nozzle 113 has a funnel shape, and a discharge port 113a is provided downward at its tip. A supply pipe 43 is connected to the cylinder portion 111.

[0033] A drive motor 115 is provided above the nozzle device 101. A rotary shaft 116 is connected to the output shaft of the drive motor 115 via a coupling (not shown). The rotational driving force of the drive motor 115 is transmitted to the rotary shaft 116. A stirring blade 117 as a stirring member combining spiral wire rods is attached to the rotary shaft 116 at a position within the storage chamber 111a of the cylinder portion 111. Note that the configuration of the nozzle device 101 is merely an example, and a configuration without the stirring blade 117, for example, may be used. At the lower end of the rotary shaft 116, a screw 114 having a spiral male thread portion formed on its outer peripheral surface is fixed in a posture hanging coaxially with the rotary shaft 116. When the screw 114 rotates at an arbitrary steady speed by the forward rotation drive of the drive motor 115, the cement-based material C in the storage chamber 111a is pushed out toward the tip of the nozzle 113 by the spiral male thread portion. Thereby, the cement-based material C in the cylinder portion 111 can be quantitatively pressure-fed toward the tip of the screw conveying portion 112.

[0034] Further, the three-dimensional modeling system 100B includes a detection device 106. The detection device 106 is a device that detects information correlated with the discharge amount of the nozzle 113. The information detected by the detection device 106 is sent to the control device 5 and used for feedback control to adjust the discharge amount of the nozzle 113. The detection device 106 of this embodiment is attached to the nozzle device 101 and measures the weight of the nozzle device 101. The detection device 106 is a tensile load cell and supports the nozzle device 101 below the Z-axis slide unit 119. That is, a part of the detection device 106 (the side fixed to the immovable body) is fixed to the lower plate 119b of the Z-axis slide unit 119, and a part of the detection device 106 (the side that measures the load) supports the frame unit 118 attached to the cylinder unit 111 via the bracket 106a. The frame unit 118 shown in FIG. 10 plays a role of reinforcing the nozzle device 101 and is attached so as to surround the cylinder unit 111. The frame unit 118 mainly includes a lower plate 118a disposed below the cylinder unit 111, a motor plate 118c used for fixing the drive motor 115, and a Z-axis frame 118d that connects the lower plate 118a and the motor plate 118c.

[0035] Also, as shown in FIG. 10, a pair of linear bushes 118g are installed side by side in the vertical direction on the side portion of the Z-axis frame 118d of the frame unit 118. A linear shaft 119d fixed to the Z-axis frame 119a of the Z-axis slide unit 119 is inserted through the linear bush 118g. The linear shaft 119d is fixed via a shaft holder 119c provided on the side surface of the Z-axis frame 119a and is arranged along the Z-axis. By the linear shaft 119d and the linear bush 118g, the load detected by the detection device 106 is limited to the load in the Z-axis direction (vertical load). The three-dimensional modeling system 100B according to the second embodiment described above can also achieve substantially the same effects as the first embodiment. That is, in the three-dimensional modeling system 100B according to the second embodiment, even if the fluidity of the cement-based material C changes due to environmental factors such as the passage of time and temperature changes, the discharge amount from the nozzle 113 is always constant and stable. As a result, it is possible to prevent a decrease in lamination accuracy, disturbance, and collapse of the modeled object.

[0036] As described above, each embodiment of the present invention has been explained. However, the present invention is not limited thereto and can be implemented without departing from the spirit of the claims. For example, in each embodiment and its variations, as information correlated with the discharge amount of the nozzles 13, 113, the detection devices 6, 7, 106 detected the decrease in the weight of the nozzles and the weight of the table on which the shaped object was formed. However, for example, a sensor that detects the flow rate of the cement-based material C discharged from the nozzle, or an image analysis means that calculates the flow rate of the cement-based material C discharged by analyzing an image of the cement-based material C discharged from the nozzle may be used as the detection device. Also, in each embodiment, PI control has been described as feedback control, but other controls (for example, current value control, analog control, etc.) may be used.

Explanation of Signs

[0037] 1, 101 Nozzle device 2, 102 Nozzle support device 3 Table device 103 Production table 3a, 103a Forming surface 4 Supply device 5 Control device 6, 106 Detection device 7 Detection device 11 Cylinder part 12 Screw conveyance part 13 Nozzle 15 Drive motor 18 Frame part 19 X-axis slide mechanism 21 X-axis rail 22 Y-axis rail 23 Z-axis column 31 Production table 32 Production table 33 Column frame 34 Table level adjustment screw 35 Lower frame 41 Hopper 42 Pump 43 Supply pipe Computers 51a, 51b 3D printer controller 52 (first control device) Motor controller 54a Motor controller 54b (second control device) Stereolithography systems 100A, 100B Z-axis slide unit 119 X-axis rail 121 Y-axis rail 122 Z-axis column 123 Lifting mechanism 124

Claims

1. A three-dimensional modeling system for forming a three-dimensional object by laminating cement-based materials, comprising: a nozzle for discharging the cement-based material; a screw that rotates to discharge the cement-based material from the nozzle; a detection device for detecting information correlated with the discharge amount of the nozzle; a control device for adjusting the rotation speed of the screw so that the discharge amount of the nozzle becomes constant based on the detection result of the detection device. A three-dimensional modeling system characterized by the above.

2. The control device includes a first control device that outputs a control signal for controlling the rotation speed of a motor that drives the screw, and a second control device that corrects the control signal by feedback control. The first control device has information indicating the relationship between the moving speed of the nozzle and the rotation speed of the screw, and outputs a first pulse signal corresponding to the moving speed of the nozzle. The second control device adjusts the period of the first pulse signal based on the detection result of the detection device, and outputs the adjusted second pulse signal to the motor. The three-dimensional modeling system according to Claim 1, characterized by the above.

3. The three-dimensional modeling system according to Claim 2, wherein the second control device adjusts the period of the first pulse signal by PI control.

4. The detection device is a load cell that measures the weight of the nozzle, and detects a decrease in the weight of the nozzle as information correlated with the discharge amount of the nozzle. The three-dimensional modeling system according to any one of Claims 1 to 3, characterized by the above.

5. The system further includes a supply device for supplying the cement-based material to the nozzle. The control device keeps the rotation speed of the screw constant without changing it during the period when the cement-based material is being supplied by the supply device. The three-dimensional modeling system according to Claim 4, characterized by the above.

6. The detection device is a load cell that measures the weight of the table on which the object is formed, and detects an increase in the weight of the table as information correlated with the discharge amount of the nozzle. The three-dimensional modeling system according to any one of Claims 1 to 3, characterized by the above.

7. The detection device is a sensor that detects the flow rate of the cementitious material discharged from the nozzle, or an image analysis means that calculates the flow rate of the cementitious material discharged by analyzing an image of the cementitious material discharged from the nozzle. The three-dimensional modeling system according to any one of claims 1 to 3, characterized by the above.

8. A three-dimensional modeling method for forming a three-dimensional object by laminating a cementitious material, The three-dimensional modeling method forms the object by discharging the cementitious material from a nozzle by rotating a screw, A detection step of detecting information correlated with the discharge amount of the nozzle, A control step of adjusting the rotation speed of the screw so that the discharge amount of the nozzle becomes constant based on the detection result of the detection step, and The detection step and the control step are repeatedly executed, A three-dimensional modeling method, characterized by the above.

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