Patent Publication Number: US-2022234283-A1

Title: Optical shaping device

Description:
TECHNICAL FIELD 
     The present invention relates to an optical shaping device that forms a shaped object by irradiating a liquid photocurable resin with light to cure the photocurable resin. 
     BACKGROUND ART 
     Recently, stereolithography technology has been used to produce desired products. 
     JP 3537161 B2 discloses the following. A liquid photocurable resin mixed with metal powder (powder material) is stored in a tank (resin tank), and the photocurable resin is irradiated with light from the outside to be cured. Thus, a three dimensional shaped object is formed. Thereafter, the resin is removed from the shaped object by a resin-removal step. Finally, the shaped object from which the resin has been removed is sintered to obtain a desired metal product. 
     In addition, JP 4246220 B2 discloses the following. A shaping container (resin tank) for storing a photocurable resin and a pump are connected by a pipe, and the pump is driven to stir the photocurable resin in the shaping container. This prevents separation between the fine particle material (powder material) and the liquid photocurable resin. 
     SUMMARY OF THE INVENTION 
     Incidentally, when the content of the powder material mixed in the photocurable resin is increased, the viscosity of the liquid photocurable resin increases, and the fluidity decreases. Accordingly, when optical shaping is performed in a state where the photocurable resin is stored, a stirring device or the like for uniformly mixing the powder material with the photocurable resin is necessary. In addition, in order to stir the photocurable resin having a high viscosity, the stirring device must have a high output. As a result, the optical shaping device including the stirring device becomes large. 
     In addition, in a case where a photocurable resin mixed with a powder material is supplied to a resin tank from the outside and the photocurable resin is poured to a light irradiation location (shaping portion), since the photocurable resin has low fluidity, it takes time until the photocurable resin reaches the shaping portion. As a result, the time taken to form the shaped object becomes longer. (Hereinafter, a photocurable resin that is a mixture with a powder material may be simply referred to as a “photocurable resin”). 
     Further, even when the powder material in the liquid photocurable resin is sufficiently mixed and stirred before shaping, if the photocurable resin is stored for a predetermined time or longer before shaping, the powder material present in the shaped object of the photocurable resin becomes non-uniform. As a result, the shape accuracy of a final product obtained by sintering the shaped object is reduced, and the mechanical characteristics of the final product are reduced. 
     The present invention has been made in consideration of such problems. It is an object of the present invention to provide an optical shaping device capable of maintaining a state where a powder material in a liquid photocurable resin is uniformly mixed without providing a stirring mechanism for stirring the photocurable resin in the optical shaping device, improving a shaping speed by preventing a decrease in fluidity even when a large amount of powder material is mixed, and allowing a final product having high shape accuracy and high mechanical characteristics to be obtained. 
     An aspect of the present invention relates to an optical shaping device comprising: a resin tank in which at least a bottom surface portion has a light-transmitting property and to which a photocurable resin that is in a liquid form and mixed with a powder material is supplied; a light irradiation mechanism configured to irradiate the photocurable resin with light via the bottom surface portion to cure the photocurable resin and form a shaped object; and a holding unit configured to move relative to the photocurable resin so as to be movable toward and away from the photocurable resin while holding the shaped object. 
     The optical shaping device further comprises: a resin supply unit provided at one end portion of the resin tank and configured to supply the photocurable resin to the resin tank; and a resin discharge unit provided at another end portion of the resin tank and configured to discharge the photocurable resin supplied to the resin tank. The resin tank is configured to cause the photocurable resin to flow from the one end portion toward the another end portion at least during formation of the shaped object. 
     According to the present invention, a shaped object is formed while causing a liquid photocurable resin to flow in one direction in a resin tank without storing the photocurable resin in the resin tank. This makes it unnecessary to stir the photocurable resin in the resin tank. In addition, at least during the formation of the shaped object, the photocurable resin mixed with the powder material constantly flows. Therefore, even when the powder material is contained at a high concentration in the liquid photocurable resin, it is possible to avoid a decrease in the fluidity of the liquid photocurable resin while preventing separation between the photocurable resin and the powder material. Further, the liquid photocurable resin can be supplied to the resin tank in a state where the powder material is uniformly dispersed therein. 
     As described above, retention and convection of the liquid photocurable resin do not occur in the resin tank. Therefore, the shaped object can be formed by irradiating the liquid photocurable resin with light in a state where the powder material is uniformly distributed therein. Accordingly, it is possible to uniformly distribute the powder material in the shaped object while improving the shaping speed. As a result, a final product having high shape accuracy and high mechanical characteristics can be obtained from the shaped object. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram of an optical shaping device according to the present embodiment; 
         FIG. 2  is a cross-sectional view of a resin tank of  FIG. 1 ; 
         FIG. 3  is a plan view of the resin tank of  FIG. 1 ; 
         FIG. 4  is a side view illustrating an example of a specific configuration of the resin tank of  FIG. 1 ; and 
         FIG. 5  is a partial side view illustrating a modified example of a light irradiation mechanism of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE INVENTION 
     Hereinafter, a preferred embodiment of an optical shaping device according to the present invention will be described with reference to the accompanying drawings. 
     1. Configuration of Present Embodiment 
     As shown in  FIG. 1 , an optical shaping device  10  according to the present embodiment forms a three dimensional shaped object  14  by irradiating a liquid photocurable resin  12  with light to cure the photocurable resin  12 . That is, the optical shaping device  10  is a so-called 3D printer. 
     As shown in  FIGS. 1 to 3 , the optical shaping device  10  includes a resin tank  18 , a resin supply unit  20 , a resin discharge unit  22 , a light irradiation mechanism  24 , a holding unit  26 , a tank  28 , and a control unit  30 . 
     The resin tank  18  is a substantially rectangular container having a relatively shallow depth (for example, a depth of about 5 mm), and the upper side thereof is open. A light-transmissive member  34  made of glass or the like is provided at a central portion of a bottom surface portion  32  of the resin tank  18 . An upper surface (a surface in contact with the photocurable resin  12 ) of the light-transmissive member  34  is coated with a non-adhesive coating (not shown), for example, a fluorine coating, in order to facilitate peeling of the cured photocurable resin  12 . 
     The liquid photocurable resin  12  mixed with a powder material  36  is supplied to the resin tank  18 . The powder material  36  is powder of a metal material constituting a desired final product to be described later. In addition, the liquid photocurable resin  12  is formed into a paste by being mixed with the powder material  36 , and is cured by light (laser light  38 ) emitted from the light irradiation mechanism  24  via the light-transmissive member  34 . In the following description, the liquid photocurable resin  12  mixed with the powder material  36  may be referred to as “photocurable resin  12 ” and explained for convenience. 
     The resin supply unit  20  that supplies the photocurable resin  12  to the resin tank  18  is provided at one end portion  40  (left end portion in  FIGS. 1 to 3 ) of the resin tank  18 . On the other hand, the resin discharge unit  22  for discharging (recovering) the photocurable resin  12  in the resin tank  18  is provided at another end portion  42  (right end portion in  FIGS. 1 to 3 ) of the resin tank  18 . In the present embodiment, the resin tank  18  is entirely inclined obliquely downward from the one end portion  40  toward the other end portion  42  at an inclination angle θ (an arbitrary angle within a range of, for example, 0° to 15°) by an adjustment mechanism  44  (see  FIG. 4 ) to be described later. Accordingly, in the resin tank  18 , flow of the photocurable resin  12  is generated from the resin supply unit  20  (the one end portion  40 ) toward the resin discharge unit  22  (the other end portion  42 ) via the bottom surface portion  32 . 
     The resin supply unit  20  includes a plate  20   a  disposed on the one end portion  40  side of an upper surface of the resin tank  18 , and a nozzle  20   b  extending in the vertical direction with respect to the plate  20   a  and communicating with the resin tank  18  through the plate  20   a.  As shown in  FIGS. 1 to 3 , the nozzle  20   b  is provided in the plate  20   a  on one end side of the resin tank  18 . An inclined portion  46  is formed on one end portion  40  side of the resin tank  18 . In the side view of  FIG. 1  and the cross-sectional view of  FIG. 2 , the inclined portion  46  is inclined obliquely downward from the position of the nozzle  20   b  toward the bottom surface portion  32  and the light-transmissive member  34 . In the plan view of  FIG. 3 , the inclined portion  46  expands from the position of the nozzle  20   b  toward the bottom surface portion  32  and the light-transmissive member  34 . 
     A supply adjustment unit  48  for adjusting the supply amount of the photocurable resin  12  when the photocurable resin  12  is supplied from the one end portion  40  toward the other end portion  42  of the resin tank  18  is provided at a distal end portion of the plate  20   a  in the resin supply unit  20 . The supply adjustment unit  48  is a substantially L-shaped member in the side view of  FIG. 1  and the cross-sectional view of  FIG. 2 . In this case, a gap d having a predetermined width is formed between a distal end portion of the supply adjustment unit  48  and the bottom surface portion  32  of the resin tank  18 . The gap d is set at a position corresponding to an amount necessary for forming at least one layer (for example, a thickness of 0.01 mm to 0.5 mm) of the shaped object  14  when the liquid photocurable resin  12  is caused to flow from the one end portion  40  toward the other end portion  42  of the resin tank  18 . 
     Accordingly, the inclined portion  46 , that is, the portion from the nozzle  20   b  to the supply adjustment unit  48 , functions as a chamber that stores the photocurable resin  12  on the upstream side in the flow direction of the photocurable resin  12  in the resin tank  18 . In this case, as shown in  FIG. 3 , the supply adjustment unit  48  side of the inclined portion  46  is set to be wider than the holding unit  26 . In addition, the supply adjustment unit  48  functions as a regulation plate having the gap d (opening) that regulates the flow of the photocurable resin  12  from the chamber. 
     On the other hand, the resin discharge unit  22  includes a plate  22   a  disposed on the other end portion  42  side of the upper surface of the resin tank  18 , and a nozzle  22   b  extending in the vertical direction with respect to the plate  22   a  and communicating with the resin tank  18  through the plate  22   a.  As shown in  FIGS. 1 to 3 , the nozzle  22   b  is provided in the plate  22   a  on the other end side of the resin tank  18 . An inclined portion  50  is provided on the other end portion  42  side of the resin tank  18 . In the side view of  FIG. 1  and the cross-sectional view of  FIG. 2 , the inclined portion  50  is inclined obliquely upward from the light-transmissive member  34  and the bottom surface portion  32  toward the position of the nozzle  22   b.  In the plan view of  FIG. 3 , the inclined portion  50  has a substantially rectangular shape. 
     A heater  52  is provided below the bottom surface portion  32  of the resin tank  18 . The heater  52  heats and keeps (maintains) the photocurable resin  12  in the resin tank  18  at a predetermined temperature (for example, 60° C. to 80° C.) by heating the entire resin tank  18 . Further, a vibration applying unit  54  such as an ultrasonic vibrator for applying vibration to the photocurable resin  12  in the resin tank  18  is provided below the bottom surface portion  32  of the resin tank  18 . 
     The light irradiation mechanism  24  is disposed below the resin tank  18  and includes a laser light source  24   a  and a scanner  24   b.  The laser light source  24   a  outputs the laser light  38  having a predetermined wavelength (for example, light having an ultraviolet wavelength) that enables the liquid photocurable resin  12  to be cured. The scanner  24   b  scans (irradiates), via the light-transmissive member  34 , the liquid photocurable resin  12  with the laser light  38  from the laser light source  24   a.    
     The holding unit  26  is provided above the light-transmissive member  34  in the resin tank  18 . In the side view of  FIG. 1  and the cross-sectional view of  FIG. 2 , the holding unit  26  is formed in a substantially trapezoidal shape in which a bottom surface portion is inclined obliquely downward correspondingly to the inclination angle θ. A moving unit  56 , which is a rising and falling unit such as a piston, is connected to an upper end portion of the holding unit  26 . When the holding unit  26  is moved up and down by the moving unit  56 , the holding unit  26  can move relative to the liquid photocurable resin  12  flowing on the upper surface of the light-transmissive member  34  so as to be movable toward and away from the liquid photocurable resin  12 . 
     Note that the holding unit  26  is in contact with the photocurable resin  12  such that the bottom surface portion thereof sinks into the flowing photocurable resin  12 . Further, the holding unit  26  is formed to be relatively thick so as not to sink into the photocurable resin  12  as a whole. 
     As described above, the liquid photocurable resin  12  is cured by being scanned with the laser light  38  from the scanner  24   b  via the light-transmissive member  34 . The holding unit  26  holds the cured photocurable resin  12 . The shaped object  14  having a predetermined shape can be formed by moving up and down the holding unit  26  with respect to the photocurable resin  12  by the moving unit  56 . 
     The tank  28  stores the liquid photocurable resin  12  mixed with the powder material  36 . A resin supply path  58  is connected between a lower end portion of the tank  28  and the resin supply unit  20 . A supply pump  60  is disposed in the middle of the resin supply path  58 . On the other hand, a resin recovery path  62  is connected between an upper end portion of the tank  28  and the resin discharge unit  22 . A discharge pump  64  is disposed in the middle of the resin recovery path  62 . The upper end portion of the tank  28  is provided with an air pump  66  that pumps air, and an inspection hole  68  through which loading of the powder material  36  or the like and the condition inside the tank  28  are observed. 
     The above-described configuration is an example. Instead of the supply pump  60 , the discharge pump  64 , and the air pump  66 , one vacuum pump may be disposed at the position of the discharge pump  64 . In this case, the photocurable resin  12  in the resin discharge unit  22  is sucked by the negative pressure of the vacuum pump and returned into the tank  28 , and the pressure in the tank  28  is reduced, whereby air bubbles in the photocurable resin  12  can be removed and the accuracy of optical shaping can be improved. 
     The control unit  30  is a computer that controls the entire optical shaping device  10 , and controls driving of the light irradiation mechanism  24  (the laser light source  24   a  and the scanner  24   b ), the heater  52 , the vibration applying unit  54 , the moving unit  56 , the supply pump  60 , the discharge pump  64 , and the air pump  66  by reading and executing a program stored in a storage unit (not shown). 
     In  FIGS. 1 to 3 , the configuration of the optical shaping device  10  is conceptually illustrated.  FIG. 4  is a side view illustrating an example of a specific configuration around the resin tank  18  in the optical shaping device  10 . 
     In  FIG. 4 , the light irradiation mechanism  24  is disposed on a mounting table  70  having a substantially rectangular shape. The light irradiation mechanism  24  includes the laser light source  24   a,  a bending portion  24   d  that bends upward the laser light  38  output in the horizontal direction from the laser light source  24   a,  and a projector  24   e  that projects upward the bent laser light  38  as a luminous flux  72 . That is, in the example of  FIG. 4 , the scanner  24   b  of  FIG. 1  is replaced with the bending portion  24   d  and the projector  24   e.    
     The adjustment mechanism  44  capable of adjusting the inclination angle θ to an arbitrary angle is disposed on an upper surface of the mounting table  70 . The adjustment mechanism  44  includes a base  44   a  that is supported by a support column  74  extending upward from the mounting table  70  and that extends in the horizontal direction, and an inclined plate  44   b  that can be inclined at an arbitrary angle with respect to the base  44   a.  A support plate  44   c  is supported by a plurality of support columns  76  extending upward from the inclined plate  44   b,  and the resin tank  18  is disposed on the support plate  44   c.    
     In this case, one end portion side and the other end portion side of the base  44   a  protrude upward. A plurality of substantially arc-shaped angle adjustment grooves  78  are formed on one end portion side, the other end portion side, and a central portion of the base  44   a.  The inclined plate  44   b  is provided with a plurality of bolts  80  inserted through holes (not shown). The plurality of bolts  80  are also inserted into the angle adjustment grooves  78 . In this case, in a state where the plurality of bolts  80  are loosened, the inclined plate  44   b  is rotated with respect to the base  44   a  along the plurality of angle adjustment grooves  78 , and then the bolts  80  are tightened, whereby the inclined plate  44   b  can be fixed to the base  44   a  at a desired inclination angle θ. As described above, the resin tank  18  is supported by the inclined plate  44   b  via the support plate  44   c  and the plurality of support columns  76 . Therefore, by adjusting the inclination angle of the inclined plate  44   b  with respect to the base  44   a  to the inclination angle θ, the resin tank  18  can be inclined at the inclination angle θ with respect to the horizontal direction. 
       FIG. 4  shows an example of the configuration of the adjustment mechanism  44 . In the present embodiment, the adjustment mechanism  44  may have any configuration as long as the resin tank  18  can be inclined at a desired inclination angle θ with respect to the horizontal direction. 
     In addition, the light irradiation mechanism  24  is not limited to the above-described configuration, and may have a configuration shown in  FIG. 5 . Like a general 3D printer, the light irradiation mechanism  24  shown in  FIG. 5  may include the laser light source  24   a,  one or more galvano mirrors  24   f  that polarize, toward the resin tank  18 , the laser light  38  output from the laser light source  24   a,  and an F-θ lens  24   g  that adjusts the shape of the laser light  38 . 
     2. Operation in Present Embodiment 
     The operation of the optical shaping device  10  configured as described above will be described with reference to  FIGS. 1 to 5 . 
     First, the resin tank  18  is inclined at a desired inclination angle θ by the adjustment mechanism  44 . Thus, the resin tank  18  is inclined obliquely downward from the one end portion  40  toward the other end portion  42 . 
     Next, in a case where the liquid photocurable resin  12  mixed with the powder material  36  is stored in the tank  28 , the supply pump  60 , the discharge pump  64 , and the air pump  66  are driven under the control of the control unit  30 . As a result, the photocurable resin  12  in the tank  28  is pressed downward by the air pumped from the air pump  66 , and is pushed out from the lower end portion of the tank  28  to the resin supply path  58 . Further, the photocurable resin  12  pushed out to the resin supply path  58  is supplied to the resin supply unit  20  by the supply pump  60 . 
     The photocurable resin  12  supplied to the resin supply unit  20  is supplied to the one end portion  40  of the resin tank  18  via the nozzle  20   b.  As described above, since the resin tank  18  is inclined at the inclination angle θ, the supplied photocurable resin  12  flows to the other end portion  42  side of the resin tank  18  via the inclined portion  46 . 
     The supply adjustment unit  48  is provided ahead in the flow direction of the photocurable resin  12 . In this case, the gap d between the distal end portion of the supply adjustment unit  48  and the bottom surface portion  32  is set to a depth necessary for forming at least one layer of the shaped object  14 . Therefore, the liquid photocurable resin  12  having a thickness corresponding to the gap d flows from the supply adjustment unit  48  to a central portion of the resin tank  18 . 
     Then, the photocurable resin  12  passes through the upper surface of the light-transmissive member  34  and reaches the other end portion  42  of the resin tank  18 . The inclined portion  50  is formed at the other end portion  42  of the resin tank  18 . This inclined portion  50  is wider than the inclined portion  46  formed at the one end portion  40  of the resin tank  18 . Accordingly, the photocurable resin  12  that has flowed to the other end portion  42  of the resin tank  18  is stored in the inclined portion  50 . 
     In this case, since the discharge pump  64  is driven, the photocurable resin  12  stored in the inclined portion  50  is discharged from the inclined portion  50  to the resin recovery path  62  via the nozzle  22   b  of the resin discharge unit  22 . The discharged photocurable resin  12  flows through the resin recovery path  62  by the discharge pump  64  and is recovered into the tank  28 . 
     The resin tank  18  is inclined at the inclination angle θ, and the supply pump  60 , the discharge pump  64  and the air pump  66  are driven. As a result, the liquid photocurable resin  12  mixed with the powder material  36  flows (circulates) through the tank  28 , the resin supply path  58 , the resin tank  18 , the resin recovery path  62 , and the tank  28  in this order without being stored, retained, or convected in the central portion of the resin tank  18 . 
     In this embodiment, by inclining the resin tank  18  at the inclination angle θ, flow of the liquid photocurable resin  12  from the one end portion  40  toward the other end portion  42  can be generated in the resin tank  18 . Therefore, in the optical shaping device  10 , at least one of the supply pump  60 , the discharge pump  64 , or the air pump  66  may be provided. 
     Further, the control unit  30  may heat and keep (maintain) the photocurable resin  12  flowing in the resin tank  18  at a predetermined temperature by driving the heater  52 . Furthermore, the control unit  30  may apply vibration to the photocurable resin  12  flowing in the resin tank  18  by driving the vibration applying unit  54 . By applying such heating or vibration, retention of the liquid photocurable resin  12  and precipitation of the powder material  36  are suppressed, and the flow of the photocurable resin  12  can be accurately controlled. 
     As long as the flow of the liquid photocurable resin  12  can be controlled, the heater  52  and the vibration applying unit  54  may be provided in the middle of the above-described circulation path of the tank  28 , the resin supply path  58 , the resin tank  18 , the resin recovery path  62 , and the tank  28 . Alternatively, the entire circulation path may be kept warm by the heater  52 , and the photocurable resin  12  may be constantly maintained at an appropriate temperature during optical shaping. 
     In a state where the flow of the liquid photocurable resin  12  is ensured in this manner, the control unit  30  drives the moving unit  56  to move up and down the holding unit  26  so as to be movable toward and away from the photocurable resin  12  flowing on the upper surface of the light-transmissive member  34 . In this case, the moving unit  56  moves the holding unit  26  such that the distance between a bottom surface of the holding unit  26  and the upper surface of the light-transmissive member  34  is equivalent to one layer of the shaped object  14 , for example, approximately 0.01 mm to 0.5 mm. In addition, the control unit  30  drives the light irradiation mechanism  24  to irradiate the photocurable resin  12  with the laser light  38  scanned by the scanner  24   b  of  FIG. 1 , the luminous flux  72  of the laser light  38  from the projector  24   e  of  FIG. 4 , or the laser light  38  from the F-θ lens  24   g  of  FIG. 5  via the light-transmissive member  34 . As a result, the liquid photocurable resin  12  irradiated with the laser light  38  is cured. 
     The cured photocurable resin  12  is held by the holding unit  26 . As described above, the photocurable resin  12  necessary for forming at least one layer of the shaped object  14  (shaped object  14  having a thickness corresponding to the gap d) flows on the upper surface of the light-transmissive member  34 , and the holding unit  26  moves up and down. Therefore, when the photocurable resin  12  is cured in a state where the holding unit  26  is in contact with the liquid photocurable resin  12 , one layer of the shaped object  14  is formed and held by the holding unit  26 . 
     When one layer of the shaped object  14  is formed, the holding unit  26  is pulled upward by the moving unit  56 . Accordingly, the shaped object  14  formed between the holding unit  26  and the light-transmissive member  34  is pulled upward in a state of being held by the holding unit  26 , and is separated from the light-transmissive member  34 . 
     Next, the moving unit  56  again moves the holding unit  26  holding one layer of the shaped object  14 , downward toward the flowing liquid photocurable resin  12 . Then, the holding unit  26  is positioned with a gap such that the distance between the light-transmissive member  34  and one layer of the shaped object  14  corresponds to one layer of the shaped object  14 , for example, approximately 0.01 mm to 0.5 mm. At this time, the photocurable resin  12  continuously flows between one layer of the shaped object  14  held by the holding unit  26  and the light-transmissive member  34 . Therefore, the photocurable resin  12  necessary for optical shaping is quickly supplied. 
     In this state, the liquid photocurable resin  12  is irradiated with the laser light  38  via the light-transmissive member  34 . As a result, the liquid photocurable resin  12  is cured, and the shaped object  14  in which the second layer continuous with the first layer is formed is obtained. 
     Therefore, the three dimensional shaped object  14  formed of a plurality of layers is formed by repeatedly performing the moving operation of the holding unit  26  by the moving unit  56  with respect to the photocurable resin  12  and the irradiation of the photocurable resin  12  with the laser light  38 . After the shaped object  14  having a desired shape is formed, the control unit  30  stops driving of the light irradiation mechanism  24 , the supply pump  60 , the discharge pump  64 , and the air pump  66 . Next, the control unit  30  causes the moving unit  56  to pull the holding unit  26  upward, thereby peeling the shaped object  14  held by the holding unit  26  from the resin tank  18 . 
     In this case, the holding unit  26  is pulled upward in a state where the light-transmissive member  34  is inclined obliquely downward. As a result, the shaped object  14  can be peeled from the light-transmissive member  34  with a smaller load than when the holding unit  26  is pulled upward in a state where the light-transmissive member  34  is disposed in the horizontal direction. In addition, since the upper surface of the light-transmissive member  34  is coated with a non-adhesive coating such as a fluorine coating, the shaped object  14  can be easily peeled from the light-transmissive member  34 . Thereafter, the shaped object  14  is peeled from the holding unit  26  that has been pulled up. 
     Next, regarding the obtained shaped object  14 , the resin is removed from the shaped object  14  by a resin removal step. Finally, the shaped object  14  from which the resin has been removed is sintered, whereby a metal product having a desired shape and made of the metal material, which is the powder material  36 , is obtained. 
     3. Effects of Present Embodiment 
     As described above, the optical shaping device  10  according to the present embodiment includes: the resin tank  18  in which at least the bottom surface portion  32  has a light-transmitting property and to which the liquid photocurable resin  12  mixed with the powder material  36  is supplied; the light irradiation mechanism  24  that irradiates the photocurable resin  12  with light (the laser light  38 , the luminous flux  72 ) via the bottom surface portion  32  (the light-transmissive member  34 ) to cure the photocurable resin  12  and form the shaped object  14 ; and the holding unit  26  that is capable of moving relative to the photocurable resin  12  so as to be movable toward and away from the photocurable resin  12  while holding the shaped object  14 . 
     In this case, the optical shaping device  10  further includes: the resin supply unit  20  that is provided at the one end portion  40  of the resin tank  18  and supplies the photocurable resin  12  to the resin tank  18 , and the resin discharge unit  22  that is provided at the other end portion  42  of the resin tank  18  and discharges the photocurable resin  12  supplied to the resin tank  18 . The resin tank  18  is configured to cause the photocurable resin  12  to flow from the one end portion  40  toward the other end portion  42  at least during formation of the shaped object  14 . 
     According to this configuration, the shaped object  14  is formed while causing the photocurable resin  12  to flow in one direction in the resin tank  18  without storing the photocurable resin  12  in the resin tank  18 . This makes it unnecessary to stir the photocurable resin  12  in the resin tank  18 . In addition, at least during the formation of the shaped object  14 , the photocurable resin  12  mixed with the powder material  36  constantly flows. Therefore, even when the powder material  36  is contained at a high concentration in the liquid photocurable resin  12 , it is possible to avoid a decrease in the fluidity of the liquid photocurable resin  12  while preventing separation between the photocurable resin  12  and the powder material  36 . In addition, the liquid photocurable resin  12  can be supplied to the resin tank  18  in a state where the powder material  36  is uniformly dispersed therein. 
     As described above, retention and convection of the photocurable resin  12  do not occur in the resin tank  18 . Therefore, the shaped object  14  can be formed by irradiating the photocurable resin  12  with the laser light  38  or the luminous flux  72  in a state where the powder material  36  is uniformly distributed therein. Accordingly, it is possible to uniformly distribute the powder material  36  in the shaped object  14  while improving the shaping speed. As a result, a final product having high shape accuracy and high mechanical characteristics can be obtained from the shaped object  14 . 
     The optical shaping device  10  further includes: the tank  28  for storing the photocurable resin  12 ; the resin supply path  58  for supplying the photocurable resin  12  from the tank  28  to the resin supply unit  20 ; the resin recovery path  62  for recovering the photocurable resin  12  from the resin discharge unit  22  into the tank  28 ; the pump  60 ,  64  that is provided in at least one of the resin supply path  58  or the resin recovery path  62  and pumps the photocurable resin  12 ; and the heater  52  for maintaining the photocurable resin  12  at a predetermined temperature. As a result, the circulation path of the photocurable resin  12  and the holding unit  26  are heated and maintained at a temperature that enables the fluidity of the photocurable resin  12  to increase. As a result, the work of forming the shaped object  14  can be smoothly performed while suppressing retention of the photocurable resin  12  and precipitation of the powder material  36  in the optical shaping device  10 . 
     Specifically, the resin tank  18  may be inclined from the one end portion  40  toward the other end portion  42 . Accordingly, it is possible to complete the work of forming (operation of shaping) a plurality of layers of the three dimensional shaped object  14  without causing the photocurable resin  12  to remain in the resin tank  18 . In addition, when one layer is formed, it is possible to quickly cause the liquid photocurable resin  12  to flow between the shaped object  14  and the resin tank  18 , and replenish the liquid photocurable resin  12 . As a result, it is possible to shorten the cycle time until the shaping operation of the next layer. 
     In addition, since the resin tank  18  is inclined, when the holding unit  26  is raised after the formation of the shaped object  14 , even in a case where the shaped object  14  is firmly attached to the resin tank  18 , the shaped object  14  can be easily peeled from the resin tank  18  on one end side of the shaped object  14 . Accordingly, it is possible to avoid occurrence of damage or the like of the shaped object  14  due to the shaped object  14  being forcibly peeled off from the resin tank  18 . That is, the shaped object  14  can be peeled from the resin tank  18  without applying a large load. Therefore, it is possible to avoid damage to the resin tank  18  and the shaped object  14 . 
     Here, the optical shaping device  10  further includes the moving unit  56  that moves the holding unit  26  in the vertical direction relative to the photocurable resin  12  when the resin tank  18  is inclined from the one end portion  40  toward the other end portion  42  at an arbitrary angle (inclination angle θ) with respect to the horizontal direction. As a result, the above-described effects can be easily obtained. 
     The optical shaping device  10  further includes the adjustment mechanism  44  capable of adjusting the inclination angle θ from the one end portion  40  toward the other end portion  42  of the resin tank  18  to an arbitrary angle. Thus, even if the viscosity of the photocurable resin  12  used for optical shaping changes, the photocurable resin  12  can be stably supplied to the resin tank  18  by arbitrarily changing the inclination angle θ. As a result, the shaping accuracy is improved, and optical shaping can be rapidly performed. 
     The optical shaping device  10  further includes the vibration applying unit  54  that applies vibration to the photocurable resin  12  in the resin tank  18 . As a result, it is possible to easily control the flow of the photocurable resin  12  and increase the shaping accuracy. 
     The optical shaping device  10  further includes the supply adjustment unit  48  for supplying, from the one end portion  40  toward the other end portion  42 , the photocurable resin  12  to a depth necessary for forming at least one layer of the shaped object  14 , when the photocurable resin  12  supplied from the resin supply unit  20  to the resin tank  18  is caused to flow from the one end portion  40  toward the other end portion  42 . Thus, the minimum necessary amount of the photocurable resin  12  can be caused to flow and supplied to the resin tank  18 . As a result, separation between the powder material  36  and the photocurable resin  12  can be prevented. Accordingly, the liquid photocurable resin  12  always mixed with a suitable amount of the powder material  36  can be irradiated with the laser light  38  or the luminous flux  72 . As a result, it is possible to easily obtain the shaped object  14  that enables a final product (metal product) to have high shape accuracy, high density, and high rigidity. 
     It should be noted that the present invention is not limited to the above-described embodiment, and various configurations can be adopted therein based on the description of the present specification.