A three-dimensional printer (1) includes a material supply device (3) that supplies material powder to a table which is movable vertically, a powder retaining wall (26) that surrounds the table and retains the material powder, a material-recovery bucket (30) that accommodates excess material powder and impurities discharged from the powder retaining wall, an impurity removing device (43) that removes the impurities from the material powder, and a material drying device (47) that dries the material powder. The material powder from which the impurities have been removed and which has been dried is returned and recycled to the material supply device.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan Application no. 2016-109991, filed on Jun. 1, 2016. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a three-dimensional printer. Particularly, the present invention relates to a three-dimensional printer that recovers an excess of material powder supplied into a chamber, removes impurities therefrom, and then supplies the resultant material powder to the chamber again.

Description of Related Art

In lamination molding of metal using a laser beam, a desired three-dimensional object including a plurality of sintered layers is formed by repeating operations of supplying material powder onto a table, which is disposed in a chamber as a build chamber filled with inert gas and is movable vertically, to form a powder layer by a material supply device, irradiating a predetermined part of the powder layer with a laser beam to sinter the material powder at the irradiated position, and stacking the sintered layers. In lamination molding using a cutting unit in a chamber, cutting may be performed on an object during molding or a molded object.

In a three-dimensional printer disclosed in US 2016/0067781, a table which is movable vertically inside a powder retaining wall is lowered to a position of a powder discharging section and excess material powder along with impurities such as spatters and cutting chips is discharged to a bucket outside the powder retaining wall. Further, excess material powder scraped by a blade along with the impurities when forming a powder layer is discharged to the bucket. The material powder in the bucket is sieved with a sieve by an operator to remove the impurities and is then returned to a material supply device by the operator.

In a powder material recycling device in manufacturing a three-dimensional object, which is disclosed in Japanese Patent No. 4561187, material components of a powder material from which cutting chips have been removed using a sieve are inspected and a powder material replenished with lacking material components based on the inspection result is supplied again onto a table.

In a three-dimensional molding device disclosed in Japanese Unexamined Patent Application Publication No. 2002-292751, a residual powder material which has been recovered into a powder recovery tank by a powder conveying unit using a cyclone separator is conveyed to a hopper of a material supply unit and is supplied again to a molding stage. In the three-dimensional molding device disclosed in Japanese Unexamined Patent Application Publication No. 2002-292751, powder intake efficiency is increased by providing a shutter mechanism in the cyclone separator and providing a sufficient closed structure in a state in which the shutter mechanism is closed.

SUMMARY OF THE INVENTION

However, while non-sintered material powder which is recycled along with impurities is discharged into the bucket outside the powder retaining wall, has the impurities removed therefrom, and is then supplied to the material supply device again, for example, there is concern that powder grains may absorb ambient moisture in the bucket partially due to an ambient environment of the three-dimensional printer, are likely to stick to each other as an aggregate, and degrade circulation of the material in the material supply device. Accordingly, there is a likelihood that long-time automated lamination molding work will be hindered.

Therefore, an object of the present invention is to enable smooth formation of a powder layer using recycled non-sintered material powder and to enable long automation of lamination molding work while maintaining high processing accuracy.

According to the invention, there is provided a three-dimensional printer (1) including: a chamber (2) that covers a molding region (R) on a base (4) and is filled with inert gas at a predetermined concentration; a table (5) that is disposed in the molding region (R) in the chamber (2) and is movable vertically; a material supply device (3) that supplies non-sintered material powder onto the table (5); a powder retaining wall (26) that surrounds the table (5) and retains the material powder supplied from the material supply device (3) onto the table (5); a material-recovery bucket (30) that accommodates excess material powder discharged from the powder retaining wall (26) along with impurities; an impurity removing device (43) that removes the impurities from the material powder including impurities in the material-recovery bucket (30); and a material drying device (47) that dries the material powder which is returned from the material-recovery bucket (30) to the material supply device (3), wherein the material powder from which the impurities have been removed by the impurity removing device (43) is returned and recycled to the material supply device (3).

According to the invention, it is possible to enable smooth formation of a powder layer using recycled non-sintered material powder and to enable long automation of lamination molding work while maintaining high processing accuracy.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings. Various features described in the following embodiment can be combined with each other. InFIG. 2, an inert gas supply and discharge system is omitted.

As illustrated inFIG. 1, a three-dimensional printer1includes a base4, a chamber2that covers a necessary molding region R on the base4, a table5that is disposed in the molding region R and moves vertically, a material supply device3that supplies material powder to the molding region R, and a laser beam irradiation unit13that irradiates the material powder with a laser beam L to sinter the material powder.

The chamber2is filled with inert gas at a predetermined concentration. The table5is driven by a table driving mechanism31such that it is movable in an up-down direction (in a direction of arrow A inFIG. 1). The molding region R is disposed on the table5. The material supply device3includes a recoater head11and a material replenishing unit55. The recoater head11is disposed on the base4and is movable in one horizontal axis direction (a direction of arrow B inFIG. 1). The recoater head11supplies material powder to the molding region R to form a powder layer8while moving in the chamber2. The material replenishing unit55replenishes the recoater head11with material powder from the outside of the chamber2. The laser beam irradiation unit13irradiates a predetermined part of the powder layer8with a laser beam L to sinter the material powder at the irradiated position and to form a sintered layer. The three-dimensional printer1may include a cutting device50in the chamber2to improve dimensional accuracy and surface finish of an object being molded.

A powder retaining wall26is disposed around the table5. A powder retaining space32is a space surrounded by the powder retaining wall26and the table5and retains non-sintered material powder. As illustrated inFIG. 2, the powder retaining wall26has a lower powder discharging portion27a, which can discharge material powder in the powder retaining space32, on a lower part thereof. When the table5moves down to a predetermined position after molding is completed, the lower powder discharging portion27acommunicates with the powder retaining space32and discharges excess non-sintered material powder into which impurities such as spatters and cutting chips (hereinafter simply referred to as impurities) are mixed. The discharged material powder is guided to a chute29by a lower chute guide28aand is accommodated in a material-recovery bucket30via the chute29.

At least one upper powder discharging portion27bis formed in the top surface of the base4and outside the powder retaining wall26and communicates with a material-recovery bucket30. The excess non-sintered material powder and the impurities which are extruded from the recoater head11are discharged from the upper powder discharging portion27b, are guided to a chute29by an upper chute guide28b, and are accommodated in the material-recovery bucket30. The upper powder discharging portion27bmay be configured to be opened and closed in a timely manner by a shutter which is not illustrated. A shutter30bthat can open and close a supply port30aof the material-recovery bucket30in a timely manner may be disposed between the chute29and the material-recovery bucket30.

The material replenishing unit55includes a main duct82and an intermediate duct69. The main duct82accommodates excess non-sintered material powder in the material-recovery bucket30as will be described later and accommodates new material powder supplied from a material tank76if necessary. The main duct82supplies material powder supplied to a main duct top72to the intermediate duct69via a main duct bottom73. An outlet of the main duct82is opened and closed by a main duct shutter68. A bellows74is disposed between the main duct82and the chamber2. The intermediate duct69supplies material powder to the recoater head11. An outlet of the intermediate duct69is opened and closed by an intermediate duct shutter70. A bellows75is disposed between the intermediate duct69and the chamber2.

The recoater head11includes a material accommodating section that accommodates material powder supplied from a top opening and discharges the material powder from a material discharge port on the bottom. The shape of the material discharge port is a slit-like long and thin shape which is perpendicular to a moving direction (the direction of arrow B inFIG. 1) of the recoater head11. The recoater head11includes blades11fband11rb, which planarize material powder discharged from a material discharge port11cto form a powder layer8, on both side surfaces. The material powder is, for example, spherical metal powder (for example, iron powder) with an average particle diameter of 20 μm. The recoater head11includes a first supply port33aand a second discharge port34bon opposite side surfaces along one horizontal axis direction perpendicular to the moving direction (the direction of arrow B inFIG. 1) of the recoater head11to supply and discharge inert gas. The inert gas is a gas which does not substantially react with the material powder, such as nitrogen gas, argon gas, or helium gas.

The recoater head11detects an amount of material powder accommodated using a sensor, and moves just below the intermediate duct69when it is determined that replenishment is necessary. Then, the tip of the intermediate duct69in which the intermediate duct shutter70is closed is inserted from a top opening of a material accommodating section. The intermediate duct shutter70is opened to supply material powder to the material accommodating section. When supply of material powder is completed, the intermediate duct shutter70is closed. The tip of the intermediate duct69is taken out of the top opening of the material accommodating section, and the recoater head11moves away from the material replenishing unit55. The main duct shutter68is opened in a timely manner when material powder is supplied to the intermediate duct69.

The laser beam irradiation unit13is disposed above the chamber2and outputs a laser beam L. The laser beam irradiation unit13is configured to two-dimensionally scan with the laser beam L. For example, the laser beam irradiation unit3includes a laser beam source, which is not illustrated, generating a laser beam L and a pair of galvanometer scanners, which is not illustrated, two-dimensionally scanning the molding region R with the laser beam L. The laser beam L passes through a window2adisposed in the chamber2and is applied to a powder layer8formed in the molding region R. The laser beam L is not particularly limited in type as long as it can sinter material powder, and examples thereof include a CO2laser beam, a fiber laser beam, and a YAG laser beam. The window2ais formed of a material which can transmit the laser beam L. For example, when the laser beam L is a fiber laser beam or a YAG laser beam, the window2acan be formed of quartz glass.

The three-dimensional printer1may include a cutting device50in the chamber2. The cutting device50moves a machining head57to a desired position in a controllable manner using a machining head driving mechanism which is not illustrated. The machining head57includes a spindle head60and an imaging unit59. The spindle head60has a rotary cutting tool such as an end mill, which is not illustrated, attached thereto and rotates the rotary cutting tool to cut a surface or an unnecessary part of a sintered layer. The rotary cutting tool can be replaced with another rotary cutting tool during molding by an automatic tool replacing device which is not illustrated. The imaging unit59is, for example, a CCD camera. The imaging unit59is used for a process of correcting a laser beam irradiation position, a process of correcting a main spindle position, a correcting process of matching the laser beam irradiation position with the main spindle position, and the like.

An inert gas supply and discharge system includes a fume diffusing device17, an inert gas supply device15, a fume collector19, duct boxes21and23, and pipes connecting them. The inert gas supply and discharge system supplies inert gas such that the chamber2is always filled with inert gas at a predetermined concentration or more and discharges inert gas, which has been contaminated with fumes generated by irradiation with a laser beam L, from the chamber2.

A supply port for inert gas includes a first supply port33a, a second supply port33b, a sub supply port33c, and a fume diffusing device supply port33d. A discharge port for inert gas includes a first discharge port34a, a second discharge port34b, and a sub discharge port34c.

The first discharge port34ais disposed on a side plate of the chamber2. An inert gas suction device35is connected to the first discharge port34a. The second supply port33bis disposed on an end of the base4to face the first discharge port34awith a predetermined irradiation region interposed therebetween. The first supply port33ais disposed on a side surface of the recoater head11opposite to the first discharge port34a. The second discharge port34bis disposed on a side surface of the recoater head11opposite to the surface on which the first supply port33ais disposed.

The sub supply port33cis disposed on a side plate of the chamber2to face the first discharge port34a. The sub discharge port34cis disposed on the top surface of the chamber2. The fume diffusing device supply port33dis disposed on the top surface of the chamber2and supplies inert gas to the fume diffusing device17.

The fume diffusing device17is disposed on the top surface of the chamber2to cover the window2a. In the fume diffusing device17, a cylindrical diffusing member17chaving a plurality of pores17eformed therein is disposed in a cylindrical housing17aand an opening17bis formed on the bottom surface of the housing17acorresponding to the inside of the diffusing member17c. An inert gas supplying space17dis disposed between the housing17aand the diffusing member17c. A clean space17fis disposed inside the diffusing member17c. The fume diffusing device17fills the clean space17fwith clean inert gas supplied to the inert gas supplying space17dvia the pores17eand discharges the clean inert gas to the lower side of the fume diffusing device17via the opening17b. The fume diffusing device17causes the clean inert gas to flow along an irradiation route of the laser beam L to exclude fume from the irradiation route of the laser beam L, thereby preventing the window2afrom being contaminated by fumes.

The inert gas supply device15includes a first inert gas supply device15aand a second inert gas supply device15b. The first inert gas supply device15asupplies clean inert gas to the chamber2via the first supply port33aand the second supply port33b. The second inert gas supply device15bsends inert gas including fume discharged from the chamber2via the first discharge port34a, the second discharge port34b, and the sub discharge port34cto the fume collector19via the duct box21, and supplies clean inert gas from which fumes have been removed in the fume collector19to the chamber2again via the duct box23and the sub supply port33c.

The three-dimensional printer1laminates and molds an object on a molding plate7placed on the table5. The table5is adjusted to an appropriate height. The recoater head11moves from the right side of the molding region R to the left side in the direction of arrow B inFIG. 1and forms a first powder layer8on the molding plate7. The laser beam irradiation unit13irradiates a predetermined part of the powder layer8with a laser beam L to foil a first sintered layer81f. The table5moves down by a height corresponding to one layer of the powder layer8. The recoater head11moves from the left side of the molding region R to the right side and forms a second powder layer8on the sintered layer81f. The laser beam irradiation unit13irradiates a predetermined part of the powder layer18with a laser beam L to form a second sintered layer82f. By repeating the above-mentioned processes, a third sintered layer83fand desired sintered layers subsequent thereto are formed.

In the three-dimensional printer1, the cutting device50is disposed in the chamber2and a surface or an unnecessary part of a sintered compact obtained by laminating the sintered layers may be machined, for example, whenever a predetermined number of sintered layers are formed during molding of an object.

The three-dimensional printer1completes the lamination molding when a necessary number of sintered layers are formed. The table5moves down slightly whenever a sintered layer is formed. The powder retaining space32surrounded by the table5and the powder retaining wall26accommodates a molded object, excess non-sintered material powder, and impurities. The impurities include spatters which are slightly scattered when material powder is sintered with a laser beam L. The impurities include cutting chips which are cut out when a surface or an unnecessary part of a sintered compact is cut.

When the lamination molding is completed, the table5is moved down to the lower powder discharging portion27a. As a result the excess non-sintered material powder and the impurities are guided from the chute guide28ato the chute29and are accommodated in the material-recovery bucket30via the chute29.

The excess non-sintered material powder and the impurities are extruded out of the powder retaining wall26by the blades11fband11rbof the recoater head11, fall from the upper powder discharging portion27boutside the powder retaining wall26, are guided to the chute29from the upper chute guide28b, and are accommodated in the material-recovery bucket30via the chute29.

As illustrated inFIGS. 1 and 2, the three-dimensional printer1includes a material-recovery conveying device41that conveys material powder including impurities in the material-recovery bucket30, an impurity removing device43that removes impurities from the material powder including impurities which is conveyed by the material-recovery conveying device41, a material-supply bucket46that accommodates the material powder from which impurities have been removed by the impurity removing device43, a material drying device47that dries the material powder in the material-supply bucket46, and a material-supply conveying device48that conveys the material powder dried by the material drying device47to the material supply device3.

The material-recovery conveying device41and the material-supply conveying device48include a suction device44that has a suction force for suctioning gas and solid together and cyclone type filters40aand40bthat separate solids from gas before suctioning gas and solids into the suction device44and does not suction solids into the suction device44.

The suction device44may be shared by the material-recovery conveying device41and the material-supply conveying device48. One suction device44may be switchably connected to one of the material-recovery conveying device41and the material-supply conveying device48by a switching valve45. The suction device44may be included in each of the material-recovery conveying device41and the material-supply conveying device48. For example, a cleaner may be employed as the suction device44. As illustrated inFIGS. 1 and 2, the material-recovery conveying device41, the material-supply conveying device48, the suction device44, and the switching valve45may be connected to each other by pipes.

The cyclone type filters40aand40b(hereinafter simply referred to as filters40aand40b) have respective upper vertical cylinders and lower converging cones. Exhaust ports41aand48aconnected to the suction device44are disposed at the top of and coaxially with the upper vertical cylinders of filters40aand40b, respectively. A suction port41bis disposed on the upper vertical cylinder of the filter40aand a suction port48bis disposed on the upper vertical cylinder of the filter40b. A discharge port41cwhich is connected to a supply port43aof the impurity removing device43and which causes separated-out solids to fall to the outside is disposed on the bottom of the lower converging cone of the filter40a. A discharge port48cwhich is connected to a supply port72aof the material supply device3and which causes separated-out solids to fall to the outside is disposed on the bottom of the lower converging cone of the filter40b.

The filters40aand40bmay be provided with shutters41dand48dthat open and close the discharge ports41cand48cin a timely manner. The shutters41dand48dmay be configured to close the discharge ports41cand48cin order to enhance suction efficiency at the time of suction and to be opened in a timely manner when accumulated solids drop to the outside. In the filters40aand40b, tanks41eand48ethat temporarily collect separated-out solids until the shutters41dand48dare opened may be disposed just above the discharge ports41cand48c.

The filters40aand40bmove solids having a larger specific gravity than gas in a spiral air flow generated therein to the outside of the air flow by a centrifugal force, discharge solids, which lose momentum due to friction between the solids and the inner wall and fall due their own weight, from the discharge ports41cand48c, and cause the suction device44to suction only gas from the exhaust ports41aand48a.

The material-recovery conveying device41includes the filter40a. The suction port41bof the filter40ais connected to the discharge port30cof the material-recovery bucket30. The discharge port41cof the filter40ais connected to the supply port43aof the impurity removing device43. The material-recovery conveying device41conveys the non-sintered material powder including impurities, which has been collected in the material-recovery bucket30, to the impurity removing device43. In the material-recovery bucket30, a shutter30bmay be disposed in the supply port30aand may be closed during conveyance such that inert gas in the chamber2is not suctioned. The material-recovery bucket30may be provided with a vent that brings gas from the outside to the inside by a suction force during conveyance.

The material-recovery conveying device41may be provided with a switching valve42, a manual cleaning nozzle90, and a flexible hose91. One end of the hose91is connected to the manual cleaning nozzle90and the other end thereof is connected to the switching valve42. The switching valve42switchably connects one of the discharge port30cof the material-recovery bucket30and the hose91to the suction port41bof the filter40a. An operator manually moves the manual cleaning nozzle90to a desired place in the chamber2and suctions non-sintered material powder or impurities for cleaning.

The impurity removing device43may be a sieve device43including a sieve43d. A mesh of the sieve43dhas dimensions that do not allow impurities such as spatters and cutting chips which are larger than the particle size of the non-sintered material powder to pass through. The sieve43dvibrates. The sieve device43supplies the non-sintered material powder including impurities conveyed from the material-recovery conveying device41to the vibrating sieve43dfrom the supply port43aand sorts the non-sintered material powder including impurities into non-sintered material powder passing through the mesh and impurities not passing through the mesh and remaining on the sieve43d. The non-sintered material powder is accommodated in the material-supply bucket46connected to a discharge port43cof the sieve device43. The impurities are accommodated in an impurity-recovery bucket43b. The impurity removing device43can employ various sorting units without departing from the gist of the invention.

The material-supply bucket46may be provided with a shutter46bthat opens and closes a supply port46ain a timely manner. The shutter46bmay be opened only when the non-sintered material powder is accommodated in the material-supply bucket46from the sieve device43.

The material drying device47dries material powder which is returned from the material-recovery bucket30to the material supply device3. As illustrated inFIGS. 1 and 2, the material drying device47may dry the non-sintered material powder, which is accommodated in the material-supply bucket46, in the material-supply bucket46. An independent conveying device that conveys the material powder from the material-supply bucket46to the material drying device47may be omitted. The material drying device47may include a heat source that directly heats the non-sintered material powder in the material-supply bucket46. The material drying device47may include a heat source that indirectly heats the non-sintered material powder by keeping the atmosphere in the material-supply bucket46at a high temperature. The material drying device47may employ various drying units without departing from the gist of the invention.

As illustrated inFIGS. 1 and 2, the material drying device47is an electrical rod-shaped cartridge heater. The cartridge heater47is disposed vertically at the center of the inside of the material-supply bucket46. Without departing from the gist of the invention, the material drying devices47may be configured such that a desired number of heaters of a desired heating type are disposed at desired positions in the material-supply bucket46in a desired shape in a desired orientation.

The material drying device47may include an independent material drying bucket other than the material-supply bucket46shared by the impurity removing device43. In this case, an independent conveying device that conveys non-sintered material powder in the material-supply bucket46to a material drying bucket which is not illustrated is provided. The material drying device47can be disposed at an appropriate position after excess non-sintered material powder is discharged to the material-recovery bucket30until it is supplied to the material supply device3again.

The material drying device47can be disposed outside the three-dimensional printer1such that a drying heat source can be prevented from causing a thermal influence such as thermal expansion of a part of the three-dimensional printer1to hinder high-accuracy machining by the three-dimensional printer1. As illustrated inFIGS. 1 and 2, the three-dimensional printer1includes the material-recovery conveying device41that conveys material powder including impurities from the material-recovery bucket30to the impurity removing device43, the material-supply bucket46that accommodates material powder from which impurities have been removed by the impurity removing device43, and the material-supply conveying device48that conveys material powder from the material-supply bucket46to the material supply device3, and the material drying device47that dries the material powder accommodated in the material-supply bucket46. The material-supply bucket46can be disposed separated from the base4, the chamber2, and the material supply device3so as not to cause a thermal influence on the base4, the chamber2, and the material supply device3.

The material-supply conveying device48includes the filter40b. A suction port48bof the filter40bis connected to the discharge port46cof the material-supply bucket46. A discharge port48cof the filter40bis connected to the supply port72aof the main duct top72in the material supply device3. As illustrated inFIGS. 1 and 2, the filter40bis installed on the main duct82of the material supply device3. The material-supply conveying device48conveys the dried non-sintered material powder collected in the material-supply bucket46to the material supply device3in a timely manner. The material-supply bucket46may include a vent that brings gas from outside of the material-supply bucket46to the inside thereof by a suction force during conveyance.

The material supply device3may prevent a decrease of the suction force by closing the main duct shutter68instead of the shutter48d. In the material supply device3, the tank48emay be omitted and the non-sintered material powder may be collected on the main duct top72.

The three-dimensional printer1includes a controller, which is not illustrated, controlling operations of various devices. The controller controls the three-dimensional printer1such that non-sintered material powder is supplied onto the table5which moves vertically in the chamber2filled with inert gas at a predetermined concentration, excess non-sintered material powder and impurities discharged out of the powder retaining wall26which surrounds the table5and retains the non-sintered material powder are recovered together, the impurities are removed from the non-sintered material powder including impurities, and the non-sintered material powder from which impurities have been removed is supplied onto the table5again, when lamination molding is performed using non-sintered material powder. The controller controls the three-dimensional printer1such that the non-sintered material powder is dried before the recovered non-sintered material powder including impurities is supplied onto the table5for recycle.

The three-dimensional printer1repeatedly performs operations of conveying non-sintered material powder including impurities in the material-recovery bucket30to the impurity removing device43using the material-recovery conveying device41, accommodating the non-sintered material powder from which impurities have been removed by the impurity removing device43in the material-supply bucket46, drying the non-sintered material powder in the material-supply bucket46using the material drying device47, and conveying the non-sintered material powder in the material-supply bucket46to the material supply device3using the material-supply conveying device48, if necessary. The devices may be simultaneously activated if necessary when the devices can operate simultaneously.

The invention can be applied to a configuration in which at least the material-supply bucket46is shared by a plurality of three-dimensional printers1, material powder in the material-recovery bucket30of a desired three-dimensional printer1among the plurality of three-dimensional printers1is accommodated in the material-supply bucket46at a desired timing, and the material powder in the material-supply bucket46is supplied to the material supply device3of the desired three-dimensional printer1among the plurality of three-dimensional printers1at a desired timing. A plurality of three-dimensional printers1can operate automatically for a long time while keeping high machining accuracy and long-time automation can be realized.

The invention can also be applied to a configuration in which one material-recovery conveying device41, one impurity removing device43, one material-supply bucket46, one material drying device47, and one material-supply conveying device48are shared by a plurality of three-dimensional printers1, the material-recovery conveying device41is switchably connected to the material-recovery buckets30of the three-dimensional printers1using a switching valve, the material-supply conveying device48is switchably connected to the material supply devices3of the three-dimensional printers1using a switching valve, non-sintered material powder including impurities is recovered from the material-recovery bucket30of the desired three-dimensional printer1at a desired timing depending on the states of the three-dimensional printers1, the impurities are removed from the non-sintered material powder including impurities at a desired timing, the non-sintered material powder from which the impurities have been removed is dried before the non-sintered material powder is supplied to the material supply device3of the desired three-dimensional printer1, and the non-sintered material powder from which impurities have been removed and which has been dried is supplied to the desired three-dimensional printer1at a desired timing. A plurality of three-dimensional printers1can operate automatically for a long time while keeping high machining accuracy and long-time automation can be realized.

According to the invention, since excess non-sintered material powder in the material-recovery bucket30has impurities removed therefrom at an appropriate timing, is dried, and is automatically supplied to the material supply device3, it is possible to reduce an excessive amount of non-sintered material powder required for lamination molding. According to the invention, since excess non-sintered material powder in the material-recovery bucket30of a desired three-dimensional printer1among a plurality of three-dimensional printers1can have impurities removed therefrom at an appropriate timing, can be dried at an appropriate timing, and can be automatically supplied to the material supply device3of a desired three-dimensional printer1among the plurality of three-dimensional printers1, it is possible to reduce an excessive amount of non-sintered material powder required when lamination molding is performed using a plurality of three-dimensional printers1together.

The embodiment was chosen in order to explain the principles of the invention and its practical application. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be defined by the claims.