Abstract:
A lamination molding apparatus which can remove the non-sintered material powder after completion of lamination molding easily and with less time after completion of laminating/molding, is provided. According to embodiments of the present invention, a lamination molding apparatus to conduct lamination molding using a material powder, including: a chamber filled with an inert gas having a predetermined concentration; a molding table provided in the chamber, the molding table being capable of moving vertically; a powder retaining wall surrounding the molding table so as to retain the material powder supplied on the molding table; and a powder discharging section provided on or below the powder retaining wall, the powder discharging section being capable of discharging the material powder, is provided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a lamination molding device. 
         [0003]    2. Background of the Invention 
         [0004]    In a lamination molding method (laser lithography) of metal using laser beam, a very thin material powder layer is formed on a molding table capable of moving vertically, followed by irradiation of the material powder layer with a laser beam, thereby sintering the material powder. These procedures are repeated to obtain the desired modeled object. As the lamination molding proceeds, the molding table descends gradually, and thus the non-sintered material powder is maintained in a space surrounded by the molding table and a powder retaining wall provided around the molding table. 
         [0005]    After the lamination molding is completed, the non-sintered material powder need be removed from the space on the molding table, and Patent Literature 1 discloses of evacuating the non-sintered material powder using a vacuum apparatus. 
       PRIOR ART DOCUMENTS 
     Patent Literature 
       [0006]    [Patent Literature 1] JP 3770206B 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    However, the method disclosed in Patent Literature 1 requires burden and time, and thus a method for removing the non-sintered material powder more easily with less time is desirable. 
         [0008]    The present invention has been made by taking these circumstances into consideration. An object of the present invention is to provide a lamination molding apparatus which can remove the non-sintered material powder after completion of lamination molding easily and with less time. 
       Means to Solve the Problem 
       [0009]    According to the present invention, a lamination molding apparatus to conduct lamination molding using a material powder, comprising: a chamber filled with an inert gas having a predetermined concentration; a molding table provided in the chamber, the molding table being capable of moving vertically; a powder retaining wall surrounding the molding table so as to retain the material powder supplied on the molding table; and a powder discharging section provided on or below the powder retaining wall, the powder discharging section being capable of discharging the material powder, is provided. 
       Effect of the Invention 
       [0010]    In the present invention, a powder discharging section capable of discharging the material powder is provided on the powder retaining wall or below the powder retaining wall. Accordingly, the non-sintered material powder can be discharged via the powder discharging section after completion of the lamination molding, and thus the non-sintered material powder can be removed easily and with less time. 
         [0011]    Hereinafter, various embodiments of the present invention will be provided. The embodiments provided below can be combined with each other. 
         [0012]    Preferably, the lamination molding apparatus further comprises an upper wiper arranged at a periphery of the molding table, the upper wiper sliding on the powder retaining wall during movement of the molding table. 
         [0013]    Preferably, the lamination molding apparatus further comprises a bucket to receive the material powder discharged from the powder discharging section. 
         [0014]    Preferably, the lamination molding apparatus further comprises a chute to guide the material powder discharged from the powder discharging section to the bucket. 
         [0015]    Preferably, the lamination molding apparatus further comprises a chute guide fixed to the chute to guide the material powder discharged from the powder discharging section to the chute. 
         [0016]    Preferably, the lamination molding apparatus further comprises: a driving mechanism partition to surround a driving mechanism of the molding table; and a lower wiper fixed to the chute provided at a position lower than the chute, the lower wiper sliding on the driving mechanism partition during movement of the molding table. 
         [0017]    Preferably, the powder discharging section is provided below a lower limit of a stroke of the molding table during the lamination molding. 
         [0018]    Preferably, the molding table is configured so as to be raised after discharging the material powder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0019]    The above further objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein: 
           [0020]      FIG. 1  is a rough structural diagram of the lamination molding apparatus according to one embodiment of the present invention. 
           [0021]      FIG. 2  is a perspective view of the powder layer forming apparatus  3 . 
           [0022]      FIG. 3  is a perspective view of the recoater head  11 . 
           [0023]      FIG. 4  is a perspective view of the recoater head  11  observed from another angle. 
           [0024]      FIG. 5  is an explanatory drawing of the lamination molding method using the lamination molding apparatus according to one embodiment of the present invention. 
           [0025]      FIG. 6  is an explanatory drawing of the lamination molding method using the lamination molding apparatus according to one embodiment of the present invention. 
           [0026]      FIG. 7  is a perspective view showing the condition of the powder layer forming apparatus  3  when the lamination molding is completed. 
           [0027]      FIG. 8  is a cross sectional view of the molding table  5  and its surroundings in the condition of  FIG. 7 . The driving mechanism  31  is simplified. The same can be said with  FIG. 9 . 
           [0028]      FIG. 9  is a cross sectional view showing a condition where the molding table  5  is descended from the condition of  FIG. 8  so as to allow the powder discharging section  27  communicate with the powder retaining space  32 . 
           [0029]      FIG. 10  is a cross sectional view showing the condition of the major portions of the powder layer forming apparatus  3  in the condition of  FIG. 9 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]    Hereinafter, the embodiments of the present invention will be described with reference to the drawings. Here, the characteristic matters shown in the embodiments can be combined with each other. 
         [0031]    As shown in  FIGS. 1 and 2 , the lamination molding apparatus according to one embodiment of the present invention is structured by providing the powder layer forming apparatus  3  in the chamber  1 . The powder layer forming apparatus  3  comprises a base  4  having a molding region R, a recoater head  11  provided on the base  4  and being capable of moving in a horizontal uniaxial direction (direction shown by arrow B), and elongated members  9   r  and  91  provided on both sides of the molding region R along the moving direction of the recoater head  11 . The molding region R is provided with a molding table  5  capable of moving vertically by the driving mechanism  31  (direction shown by arrow A in  FIG. 1 ). When the lamination molding apparatus is used, a molding plate  7  is arranged on the molding table  5 , and a material powder layer  8  is formed on the molding table  5 . In addition, a powder retaining wall  26  is provided so as to surround the molding table  5 , and the non-sintered material powder is retained in a powder retaining space  32  surrounded by the powder retaining wall  26  and the molding table  5  (shown in  FIG. 7 ). Below the powder retaining wall  26 , a powder discharging section  27  capable of discharging the material powder in the powder retaining space  32  is provided. The material powder discharged from the powder discharging section  27  is guided to a chute  29  by a chute guide  28 , and then the material powder in the chute  29  is allowed to be contained in a bucket  30 . The method for discharging the non-sintered material powder from the powder discharging section  27  will be explained later. 
         [0032]    As shown in  FIGS. 2 and 4 , the recoater head  11  comprises a material holding section  11   a,  a material supplying section  11   b  provided on the top surface of the material holding section  11   a,  and a material discharging section  11   c  provided on the bottom surface of the material holding section  11   a  for discharging the material powder contained in the material holding section  11   a.  The material discharging section  11   c  has a slit shape which elongates in the horizontal uniaxial direction (direction shown by arrow C) crossing orthogonally with the moving direction (direction shown by arrow B) of the recoater head  11 . On both sides of the recoater head  11 , squeegee blades  11   fb  and  11   rb  for forming a material powder layer  8  by planarizing the material powder discharged from the material discharging section  11   c  are provided. In addition, on both sides of the recoater head  11 , fume suction sections  11   fs  and  11   rs  for suctioning the fume generated during sintering of the material powder are provided. The fume suction sections  11   fs  and  11   rs  are provided along the horizontal uniaxial direction (direction shown by arrow C) crossing orthogonally with the moving direction (direction shown by arrow B) of the recoater head  11 . The material powder is, for example, metal powder (iron powder for example) having a sphere shape with an average particle diameter of 20 μm. 
         [0033]    The elongated members  9   r  and  9   l  are provided with openings. Here, the openings are provided along the moving direction (direction shown by arrow B) of the recoater head  11 . One of these openings is used as the inert gas supplying opening, and the other is used as the inert gas discharging opening, thereby forming a flow of the inert gas in the direction shown by arrow C on the molding region R. Accordingly, the fume generated in the molding region R can be easily discharged along this flow of inert gas. Here, in the present specification, “inert gas” is a gas which substantially does not react with the material powder, and nitrogen gas, argon gas, and helium gas can be mentioned for example. 
         [0034]    A laser beam emitter  13  is provided above the chamber  1 . The material powder layer  8  formed in the molding region R is irradiated with the laser beam L emitted from the laser beam emitter  13  which is transmitted through a window la provided in the chamber  1 . The laser beam emitter  13  need be structured so as to allow two-dimensional scanning of the laser beam L. For example, the laser beam emitter  13  is structured with a laser beam source for generating the laser beam L, and a pair of galvanometer scanner for allowing two-dimensional scanning of the laser beam L in the molding region R. There is no particular limitation to the type of the laser beam L, so long as it can sinter the material powder. For example, CO 2  laser, fiber laser, and YAG laser can be mentioned. The window la is formed with a material which can transmit the laser beam L. For example, in a case where the laser beam L is a fiber laser or a YAG laser, the window la can be structured with quartz glass. 
         [0035]    On the upper surface of the chamber  1 , the fume diffusing section  17  is provided so as to cover the window la. The fume diffusing section  17  is provided with a cylindrical housing  17   a  and a cylindrical diffusing member  17   c  arranged in the housing  17   a.  An inert gas supplying space  17   d  is provided in between the housing  17   a  and the diffusing member  17   c.  Further, on the bottom surface of the housing  17   a,  an opening  17   b  is provided at the inner portion of the diffusing member  17   c.  The diffusing member  17   c  is provided with a plurality of pores  17   e,  and the clean inert gas supplied into the inert gas supplying space  17   d  is filled into a clean space  17   f  through the pores  17   e . Then, the clean inert gas filled in the clean space  17   f  is discharged towards below the fume diffusing section  17  through the opening  17   b.    
         [0036]    Next, the inert gas supplying system to supply the inert gas into the chamber  1  and the fume discharging system to discharge the fume from the chamber  1  are explained. 
         [0037]    The inert gas supplying system to supply the inert gas into the chamber  1  is connected with the inert gas supplying apparatus  15  and the fume collector  19 . The inert gas supplying apparatus  15  has a function to supply the inert gas, and is a gas cylinder containing inert gas, for example. The fume collector  19  comprises duct boxes  21  and  23  provided at its upper stream side and its lower stream side, respectively. The gas discharged from the chamber  1  (inert gas containing fume) is sent to the fume collector  19  through the duct box  21 . Then, fume is removed in the fume collector  19 , and the cleaned inert gas is sent to the chamber  1  through the fume duct box  23 . According to such constitution, the inert gas can be recycled. 
         [0038]    As shown in  FIG. 1 , the inert gas supplying system is connected with the upper supplying opening  1   b  of the chamber  1 , the inert gas supplying space  17   d  of the fume diffusing section  17 , and the elongated member  9   l.  The inert gas is filled in the molding space  1   d  of the chamber  1  through the upper supplying opening  1   b.  The inert gas supplied into the elongated member  9   l  is discharged onto the molding region R through the opening. 
         [0039]    In the present embodiment, the inert gas from the fume collector  19  is sent to the upper supplying opening  1   b , and the inert gas from the inert gas supplying apparatus  15  is sent to the inert gas supplying space  17   d  and the elongated member  9   l . Although there is a possibility that the inert gas from the fume collector  19  contains residual fume, the constitution of the present embodiment does not permit the inert gas from the fume collector  19  be supplied into the space which requires especially high cleanliness (clean space  17   f  and the space at the periphery of the molding region R). Accordingly, the effect of the residual fume can be minimized. 
         [0040]    As shown in  FIGS. 1 and 4 , the fume discharging system to discharge the fume from the chamber  1  is connected with the fume suction sections  11   fs  and  11   rs  of the recoater head  11 , and with the elongated member  9   r . Since the inert gas containing the fume in the molding space  1   d  of the chamber  1  is discharged through the fume suction sections  11   fs  and  11   rs  of the recoater head  11 , and through the elongated member  9   r,  a flow of inert gas flowing from the upper supplying opening  1   b  towards the fume suction sections  11   fs  and  11   rs  of the recoater head  11 , and towards the elongated member  9   r  is formed in the molding space  1   d.  The fume suction sections  11   fs  and  11   rs  of the recoater head  11  can suction the fume generated in the molding region R when the recoater head  11  passes over the molding region R. In addition, the inert gas containing the fume is discharged from the chamber  1  through the opening of the elongated member  9   r.  The fume discharging system is connected with the fume collector  19  through the dust box  21 , and the inert gas after removal of the fume by the fume collector  19  is recycled. 
         [0041]    Next, referring to  FIGS. 1 ,  5 , and  6 , the lamination molding method using the lamination molding apparatus will be explained. Here, in  FIGS. 5 and 6 , the inert gas supplying system and the fume discharging system are not shown. 
         [0042]    First, the molding plate  7  is placed on the molding table  5 , and the height of the molding table  5  is adjusted to an appropriate position. In this state, the recoater head  11  with the material holding section  11   a  being filled with the material powder is moved from the left side to the right side of the molding region R, in the direction shown by arrow B in  FIG. 1 . Accordingly, a first layer of the material powder layer  8  is formed on the molding plate  7 . 
         [0043]    Subsequently, predetermined portion of the material powder layer  8  is irradiated with the laser beam L, thereby sintering the portion of the material powder layer  8  being irradiated with the laser beam. Accordingly, the first layer of sintered layer  81   f  is obtained as shown in  FIG. 5 . 
         [0044]    Then, the height of the molding table  5  is descended by the thickness of one layer of the material powder layer  8 . Subsequently, the recoater head  11  is moved from the right side to the left side of the molding region R. Accordingly, a second layer of the material powder layer  8  is formed on the sintered layer  81   f.    
         [0045]    Next, predetermined portion of the material powder layer  8  is irradiated with the laser beam L, thereby sintering the portion of the material powder layer  8  being irradiated with the laser beam. Accordingly, the second layer of sintered layer  82   f  is obtained as shown in  FIG. 6 . 
         [0046]    By repeating these procedures, the third layer of sintered layer  83   f,  the fourth layer of sintered layer  84   f , and the sintered layers thereafter are formed. The adjacent sintered layers are firmly fixed with each other. 
         [0047]    The lamination molding is completed by forming necessary number of the sintered layers. Here, the molding table  5  is descended each time the sintered layer is formed. Accordingly, when the lamination molding is completed, the molding table  5  is positioned lower than the position of the molding table  5  at the starting point as shown in  FIG. 7 . In such condition, the modeled object formed by lamination molding and the non-sintered material powder are retained in the powder retaining space  32  surrounded by the powder retaining wall  26  and the molding table  5 . As shown in  FIG. 8 , the molding table  5  is not directly in contact with the powder retaining wall  26 , and the upper wiper  33  arranged at the periphery of the molding table  5  contacts with the powder retaining wall  26 . Here, when the molding table  5  moves, the upper wiper  33  slides on the powder retaining wall  26 . With such structure, the material powder in the powder retaining space  32  can be prevented from leaking out. In addition, since the molding table  5  is heated with the heating mechanism during molding, the molding table  5  becomes hot. Therefore, a heat resistant wiper is used as the upper wiper  33 . 
         [0048]    As shown in  FIG. 8 , the powder discharging section  27  is arranged in between the powder retaining wall  26  and the chute  29 . When the molding table  5  is positioned higher than the powder discharging section  27  as shown in  FIG. 8 , the material powder in the powder retaining space  32  is not discharged from the powder discharging section  27 . On the other hand, when the molding table  5  descends so that the powder discharging section  27  communicates with the powder retaining space  32  as shown in  FIG. 9 , the non-sintered material powder in the powder retaining space  32  is guided to the chute  29  by the chute guide  28  through the pathway shown by the arrow X. The chute guide  28  is fixed to the chute  29 . 
         [0049]    A driving mechanism  31  is provided below the molding table  5  in order to move the molding table  5  vertically. The driving mechanism  31  is structured with a feed screw mechanism and the like, and thus the material powder may become a cause of malfunction if the material powder gets into the driving mechanism  31 . Therefore, in order to prevent the material powder from getting into the driving mechanism  31 , a driving mechanism partition  35  is provided so as to surround the driving mechanism  31 , and a lower wiper  36  fixed to the chute  29  is provided so as to slide on the driving mechanism partition  35  when the molding table  5  moves. With such structure, the material powder fluttering in the chute  29  can be prevented from getting into the driving mechanism  31 . In addition, regarding the driving mechanism partition  35 , a dust tray  34  is provided below the lower wiper  36  so as to receive the material powder passing between the lower wiper  36  and the driving mechanism partition  35 , as shown in  FIG. 10 . 
         [0050]    The powder discharging section  27  is provided below the lower limit of the stroke of the molding table  5  during the lamination molding. By providing the powder discharging section  27  at such position, the material powder can be prevented from being discharged from the powder discharging section  27  during the lamination molding. Then, when the mode is switched after the completion of the lamination molding so as to discharge the material powder, the molding table  5  descends to a position shown in  FIG. 9  and the material powder is discharged. Here, the material powder can be discharged by its weight. When the lamination molding takes a long time, the material powder is compressed and thus the discharge tends to become difficult. In such case, the material powder can be easily discharged by providing a mechanism to stimulate the material powder such as pressing of a pin. 
         [0051]    As described, according to the present embodiment, the non-sintered material powder can be easily discharged merely by descending the molding table  5  to a predetermined position after the completion of the lamination molding. The processing time can be shortened compared with the conventional technique, and the time the operator is exposed to powder dust can be shortened, thereby improving safety. In addition, the molding table  5  can be raised after retaining the non-sintered material powder in the bucket  30 , thereby sealing the molding space  1   d  from the space arranged with the bucket  30 . Therefore, process such as purging of the molding space  1   d  can be conducted even while the material powder is being collected from the bucket  30 , resulting in improvement in operating efficiency. 
         [0052]    The present invention can also be carried out in the following manner. 
         [0053]    In the afore-mentioned embodiment, a notch was provided at the lower end of the powder retaining wall  26 , and then the powder discharging section  27  was provided in between the powder retaining wall  26  and the chute  29 . Here, such notch is not necessary. In addition, the material powder can be directly discharged into the bucket  30  from the powder retaining space  32  without providing the chute  29 . Accordingly, it is not necessary to provide the powder discharging section  27  in between the powder retaining wall  26  and the chute  29 . The space below the powder retaining wall  26  can be simply used as the powder discharging section  27 . In addition, a through hole can be provided in the powder retaining wall  26 , and the through hole can be used as the powder discharging section  27 . That is, the powder discharging section  27  can be provided in the powder retaining wall  26  itself, of can be provided in an area lower than the powder retaining wall  26 . 
         [0054]    The powder discharging section  27  can be provided at a position higher than the lower limit of the stroke of the molding table  5  during the lamination molding. In such case, it is preferable to provide a shutter to the powder discharging section  27  in order to prevent the material powder from being discharged during the lamination molding. 
         [0055]    In the afore-mentioned embodiment, two powder discharging sections  27  were provided. Here, one or three or more powder discharging sections  27  can be provided. 
       EXPLANATION OF SYMBOLS 
       [0000]    
       
           1 : chamber 
           3 : powder layer forming apparatus 
           5 : molding table 
           8 : material powder layer 
           11 : recoater head 
           17 : fume diffusing section 
           26 : powder retaining wall 
           27 : powder discharging section 
           28 : chute guide 
           29 : chute 
           30 : bucket 
           31 : driving mechanism 
           32 : powder retaining space 
           33 : upper wiper, 
           34 : dust tray 
           35 : driving mechanism partition 
           36 : lower wiper 
         L: laser beam 
       
     
         [0074]    Although various exemplary embodiments have been shown and described, the invention is not limited to the embodiments shown. Therefore, the scope of the invention is intended to be limited solely by the scope of the claims that follow.