JP5982046B1 - Additive manufacturing equipment - Google Patents

Abstract

An object of the present invention is to provide an additive manufacturing apparatus that achieves both efficiency of fume removal and maintenance of an inert gas concentration in a chamber. A laser irradiation apparatus for irradiating a predetermined irradiation region on a material powder layer with a laser beam to form a sintered layer; an inert gas is supplied to the chamber; And an inert gas supply / exhaust device 4 that discharges to the outside. The inert gas supply / exhaust device 4 includes an inert gas supply device that supplies the chamber 10 with an inert gas and a fumes discharged from the chamber 10. A fume collector 43 comprising a suction part for sucking in the active gas, a dust collector for removing the fume from the inert gas containing the fume, and an exhaust part for returning the inert gas from which the fume has been removed into the chamber; And a bypass 47 that is connected to the exhaust part and forms a flow of inert gas from the exhaust part to the suction part and limits the flow rate of the inert gas returned into the chamber 10 to an appropriate amount. Modeling apparatus 1. [Selection] Figure 1

Description

  The present invention relates to an additive manufacturing apparatus.

  In the metal powder sintering additive manufacturing method using laser light, a metal material powder is uniformly distributed on a modeling table to form a material powder layer, and a predetermined portion of the material powder layer is irradiated with laser light to be fired. A sintered layer is formed by bonding, a metal material powder is uniformly distributed on the sintered layer to form a new material powder layer, and the new material powder layer is irradiated with laser light. To form a new sintered layer joined to the lower sintered layer, and by repeating these, a plurality of sintered layers are laminated to form a desired sintered body. Form a three-dimensional structure.

  When sintering a metal material powder with laser light, in order to protect the metal material powder from being altered and to be able to stably irradiate laser light of a required energy, It is required to keep the surroundings as oxygen free as possible. Therefore, an additive manufacturing apparatus for performing a metal powder sintering additive manufacturing method using laser light supplies an inert gas such as nitrogen gas into a sealed chamber, and an atmosphere having a sufficiently low oxygen concentration in the chamber. A predetermined irradiation region can be irradiated with laser light below.

  Further, when the metal material powder is sintered by irradiating it with laser light, specific smoke called fume is generated. When the chamber fills the chamber, the laser beam is shielded, and the laser beam having a required energy does not reach the sintering site, which may cause sintering failure.

  For this reason, in the additive manufacturing method using laser light, it is necessary to maintain the interior of the chamber in a low oxygen atmosphere and to remove fumes from the interior of the chamber. As disclosed in Patent Document 1, there is known an additive manufacturing apparatus that supplies a clean inert gas into a chamber and discharges an inert gas containing fumes from the chamber. In addition, in the additive manufacturing apparatus according to Patent Document 1, the fumes are removed from the inert gas containing the fumes discharged out of the chamber, and the inert gas in the chamber is circulated by returning it to the chamber again. Yes. In this way, the chamber is configured to be maintained in a clean inert gas atmosphere.

  Moreover, a dust collector called a fume collector is used as an apparatus for removing fume from an inert gas. As disclosed in Patent Document 2, a dust collector that generates an airflow with a blower is known in order to facilitate intake and exhaust and gas circulation inside the apparatus.

Japanese Patent No. 4131260 Japanese Patent No. 3444511

  The chamber of the additive manufacturing apparatus is configured to be hermetically sealed, but it is difficult to obtain perfect airtightness. Inert gas leaks from a slight gap and external air flows in. Therefore, it is necessary to supply the inert gas by the inert gas supply device so that the interior of the chamber is always filled with an inert gas having a predetermined concentration or more during additive manufacturing.

  In addition, if a blower is provided in the fume collector or the like and an air flow is generated so as to increase the amount of the inert gas that circulates, the amount of air passing through the inside of the fume collector increases, so that the fume can be removed in a shorter time.

  However, when the air volume of the inert gas circulating in the chamber increases, the atmospheric pressure increases near the inert gas supply port, and external leakage of the inert gas is promoted, while the atmospheric pressure decreases near the exhaust port. External air tends to flow into the chamber. Therefore, when inflow of external air at a flow rate exceeding the processing capacity of the inert gas supply device occurs, the inert gas concentration in the chamber decreases and the oxygen concentration exceeds the allowable value. There is a practical limit to the maximum supply amount of the inert gas supply device.

  The present invention has been made in view of such circumstances, and the air volume inside the fume collector is increased to efficiently remove the fume, and an appropriate amount of inert gas is returned from the fume collector into the chamber. The main object of the present invention is to provide an additive manufacturing apparatus that achieves both efficient fume removal and maintenance of the inert gas concentration in the chamber.

  According to the present invention, a material powder formed by uniformly distributing a metal material powder for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height in a sealed chamber. A laser irradiation device for forming a sintered layer by irradiating a predetermined irradiation region on the layer with a laser beam, and an inert gas in the chamber so that the chamber is always filled with an inert gas having a predetermined concentration or more And an inert gas supply / exhaust device for exhausting fumes out of the chamber, the inert gas supply / exhaust device supplying an inert gas to the chamber, and the chamber A suction section for sucking an inert gas containing fumes discharged from the dust, a dust collector for removing the fumes from the inert gas containing fumes, and an exhaust section for returning the inert gases from which the fumes have been removed to the chamber. A flow rate of the inert gas that is connected to the suction part side and the exhaust part side to form a flow of inert gas from the exhaust part side to the suction part side and is returned to the chamber. An additive manufacturing apparatus including a bypass for limiting to an appropriate amount is provided.

  In the additive manufacturing apparatus according to the present invention, the suction portion side and the exhaust portion side are connected by a bypass so that an inert gas flow from the exhaust portion side of the fume collector to the suction portion side is formed. In this way, a part or most of the inert gas that has passed through the dust collector of the fume collector is sent again to the suction unit. Therefore, even if the blower is driven so that the amount of air passing through the inside of the fume collector is increased, an increase in the flow rate of the inert gas returned from the fume collector to the chamber can be suppressed. That is, in the additive manufacturing apparatus according to the present invention, both the efficiency of fume removal and the maintenance of the inert gas concentration in the chamber are compatible.

1 is a configuration diagram of an additive manufacturing apparatus 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line DD in FIG. 1 and shows only the front chamber 11. 3 is a perspective view of a powder layer forming apparatus 3. FIG. 3 is a perspective view of a recoater head 33 and elongated members 35 and 37. FIG. It is the perspective view seen from another angle of the recoater head 33 and the elongate members 35 and 37. 2 is a configuration diagram showing details of a fume diffusing device 41. FIG. 3 is a perspective view of a fume diffusing device 41. FIG. It is a block diagram which shows the detail of the fume collector 43 and the bypass 47. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The modifications of the plurality of constituent members described below can be implemented in any combination. In the following description, in the machine body of the additive manufacturing apparatus 1, the side of the front chamber 11 on which the work door is provided is the front or front, the right hand side is the right side and the left hand side is the left side toward the front. The rear side is the back side. The dotted line in the figure indicates the irradiation path or signal line of the laser beam L.

  As shown in FIG. 1, the additive manufacturing apparatus 1 according to an embodiment of the present invention includes a chamber 10 configured to be substantially sealed, and the chamber 10 is divided into a front chamber 11 and a rear chamber 12. Yes. A modeling chamber 111 is provided in the front chamber 11, and a driving chamber 121 is provided in the rear chamber 12. An opening 115 communicating with the modeling chamber 111 is provided on the front surface of the front chamber 11, and a work door with a viewing window (not shown) is provided in the opening 115. The modeling chamber 111 and the drive chamber 121 are partitioned by an extendable X-axis bellows 14. Between the modeling chamber 111 and the drive chamber 121, there is a communication portion 15 that is a slight gap through which an inert gas can pass. The layered modeling apparatus 1 includes a control device 27 as a numerical control device that receives modeling data generated by a CAM device (not shown) and controls the layered modeling based on the received data. The control device 27 also serves as a control device for an inert gas supply device 42 and a fume collector 43 described later.

A driving device 13 is provided in the chamber 10. The driving device 13 is installed on a bed 23 disposed on the base 21. The drive device 13 includes a Y-axis drive device 133 that moves the machining head 135 disposed in the modeling chamber 111 in the Y-axis direction, and an X-axis drive device 131 that moves the Y-axis drive device 133 in the X-axis direction. The The processing head 135 includes a spindle (not shown) and is moved in the Z-axis direction by a Z-axis drive device. The spindle is configured such that it can be rotated by mounting a rotary cutting tool such as an end mill. With the above configuration, the rotary cutting tool can be relatively moved to an arbitrary position in the modeling chamber 111 to perform cutting on the sintered layer. Using this rotary cutting tool, the sintered layer may be cut every time a predetermined number of sintered layers are formed. Also, when the recoater head 33 collides with the raised portion of the sintered layer, the sintered layer may be cut to remove the raised portion.

As shown in FIGS. 2 and 3, the powder layer forming apparatus 3 is provided in the front chamber 11. The powder layer forming apparatus 3 is configured to be horizontally fixed on the bed 23 and having a modeling region R, and to be arranged on the base table 31 and movable in the horizontal uniaxial direction (arrow B direction). The recoater head 33 and elongated members 35 and 37 provided on both sides of the modeling region R along the moving direction of the recoater head 33 are provided. In the modeling region R, a modeling table 39 that is movable in the vertical direction (arrow A direction) is provided. When the additive manufacturing apparatus is used, the modeling plate 5 is disposed on the modeling table 39, and the material powder layer 6 is formed thereon.

  As shown in FIGS. 4 and 5, the recoater head 33 is provided on the material container 331 for storing the material powder supplied from the material supply device 16 shown in FIG. 2 and on the upper surface of the material container 331. The material supply unit 332 and the material discharge unit 333 that is provided on the bottom surface of the material storage unit 331 and discharges the metal material powder in the material storage unit 331 are provided. The material discharge unit 333 has a slit shape extending in a horizontal one-axis direction (arrow C direction) orthogonal to the moving direction (arrow B direction) of the recoater head 33. On both side surfaces of the recoater head 33, blades 334 and 335 for flattening the metal material powder discharged from the material discharge portion 333 to form the material powder layer 6 are provided. The metal material powder is a metal powder such as a spherical iron powder having an average particle diameter of 20 μm, for example.

  A laser irradiation device 25 is provided above the front chamber 11, and the laser light L output from the laser irradiation device 25 passes through a window 113 provided in the front chamber 11 and is formed into a material powder formed in the modeling region R The body layer 6 is irradiated. The laser irradiation device 25 is formed by uniformly distributing metal material powder in each divided layer of a plurality of divided layers obtained by dividing a three-dimensional structure of a desired shape at a predetermined height in the front chamber 11. A predetermined irradiation area on the material powder layer 6 is irradiated with laser light L having a required energy to form a sintered layer. The laser irradiation device 25 only needs to be configured to be capable of two-dimensional scanning of the laser light L in the modeling region R. For example, the laser light source that generates the laser light L and the laser light L can be two-dimensionally scanned in the modeling region R. And a pair of galvano scanners. The type of the laser beam L is not limited as long as the metal material powder can be sintered, and is, for example, a CO2 laser, a fiber laser, a YAG laser, or the like. The window 113 is formed of a material that can transmit the laser light L. For example, when the laser beam L is a fiber laser or a YAG laser, the window 113 can be made of quartz glass.

  Next, an inert gas supply system and a fume discharge system of the inert gas supply / discharge device 4 will be described. The inert gas supply / discharge device 4 according to the embodiment includes a fume diffusing device 41, an inert gas supply device 42, a fume collector 43, duct boxes 45 and 46, and a bypass 47. The inert gas supply / discharge device 4 supplies the inert gas so that the chamber 10 is always filled with an inert gas having a predetermined concentration or higher, and the inert gas contaminated by the fumes 25 generated by the irradiation of the laser beam L. The active gas is discharged out of the chamber 10. In the present specification, the inert gas is a gas that does not substantially react with the metal material powder, and examples thereof include nitrogen gas, argon gas, and helium gas.

  Further, the inert gas supply / discharge device 4 connects a plurality of inert gas supply ports and discharge ports provided in the chamber 1, and each supply port and each discharge port to the inert gas supply device 42 and the fume collector 43. Including piping to be used. The supply port of this embodiment includes a first supply port 481, a second supply port 482, a sub supply port 483, a fume diffusing device supply port 484, and a drive chamber supply port 485. The discharge port of the present embodiment includes a first discharge port 491, a second discharge port 492, a third discharge port 493, a fourth discharge port 494, and a sub discharge port 495.

  The first supply port 481 is provided to face the first discharge port 491 corresponding to the installation position of the first discharge port 491. Desirably, the first supply port 481 faces the first discharge port 491 when the recoater head 33 is positioned on the opposite side of the predetermined irradiation region with respect to the installation position of the material supply device 16. And provided on one side of the recoater head 33 along the arrow C direction.

  The first discharge port 491 is provided on the side plate of the front chamber 11 at a predetermined distance from a predetermined irradiation region so as to face the first supply port 481. A suction device 496 is provided so as to be connected to the first discharge port 491. The suction device 496 helps to efficiently remove the fumes 7 from the irradiation path of the laser light L. Further, the suction device 496 can discharge a larger amount of the fume 7 at the first discharge port 491, and the fume 7 is less likely to diffuse into the modeling chamber 111.

  The second supply port 482 is provided on the end of the base 21 so as to face the first discharge port 491 with a predetermined irradiation region in between. When the recoater head 33 passes through a predetermined irradiation region and the first supply port 481 is at a position facing the first discharge port 491 without the predetermined irradiation region in between, the second supply port 482 is The first supply port 481 is selectively switched from the second supply port 482 to be opened. For this reason, the second supply port 482 supplies an inert gas having the same predetermined pressure and flow rate as the inert gas supplied from the first supply port 481 toward the first discharge port 491, so that the second supply port 482 is always in the same direction. It is advantageous in that a flow of active gas can be created and stable sintering can be performed.

  The second discharge port 492 is provided along the arrow C direction on the side surface opposite to the one surface where the first supply port 481 of the recoater head 33 is provided. When the inert gas cannot be supplied from the first supply port 481, in other words, when the inert gas is supplied from the second supply port 482, some flow of the inert gas is created near the predetermined irradiation region. Therefore, the fumes 7 can be more efficiently removed from the irradiation path of the laser light L.

  A third discharge port 493 and a fourth discharge port 494 are provided along the arrow B direction in the elongated members 35 and 37, respectively, within a range not exceeding the maximum supply amount of the inert gas of the inert gas supply / discharge device 4. When a predetermined irradiation area is wider and a laser beam irradiation spot is present at the front or back end of the modeling area, it is formed between the first supply port 481 or the second supply port 482 and the first discharge port 491. There is a risk that the fumes 7 will not be able to ride through the flow of the inert gas. The fume 7 can be discharged more efficiently by the third discharge port 493 and the fourth discharge port 494.

  In addition, the inert gas supply / discharge device 4 of the embodiment is a clean non-removable device in which the fumes 7 provided on the side plate of the front chamber 11 so as to face the first discharge port 491 and fed from the fume collector 43 are removed. A sub-supply port 483 that supplies the active gas 8 to the modeling chamber 111, a fume diffusion device supply port 484 that is provided on the upper surface of the front chamber 11 and supplies an inert gas to the fume diffusion device 41, and is driven in the rear chamber 12. A driving chamber supply port 485 for supplying an inert gas to the chamber 121, and a sub-discharge port 495 for discharging an inert gas containing a large amount of fumes 7 provided on the upper side of the front chamber 11 provided above the first discharge port 491. Is provided.

  A fume diffusing device 41 is provided on the upper surface of the front chamber 11 so as to cover the window 113. As shown in FIGS. 6 and 7, the fume diffusing device 41 includes a cylindrical casing 411 and a cylindrical diffusing member 412 disposed in the casing 411. An inert gas supply space 413 is provided between the housing 411 and the diffusion member 412. In addition, an opening 414 is provided inside the diffusion member 412 on the bottom surface of the housing 411. The diffusion member 412 is provided with a large number of pores 415, and the clean inert gas 8 supplied to the inert gas supply space 413 through the fume diffusion device supply port 484 is filled into the clean space 416 through the pores 415. The The clean inert gas 8 filled in the clean space 416 is ejected toward the lower side of the fume diffusing device 41 through the opening 414. The jetted clean inert gas 8 flows out along the irradiation path of the laser beam L, excludes the fumes 7 from the irradiation path of the laser beams L, and prevents the window 113 from being contaminated by the fumes 7.

  An inert gas supply device 42 and a fume collector 43 are connected to the inert gas supply system to the chamber 10. The inert gas supply device 42 has a function of supplying an inert gas, and includes, for example, a membrane type nitrogen separator that extracts nitrogen gas from ambient air. The inert gas supply device 42 of the embodiment includes a first inert gas supply device 421 that supplies an inert gas through a first supply port 481 and a second supply port 482, a fume diffusion device supply port 484, and a drive chamber supply. And a second inert gas supply device 422 for supplying an inert gas through the port 485. As the first inert gas supply device 421, a device capable of managing the concentration of the inert gas is preferable. The second inert gas supply device 422 may be a device having the same configuration as the first inert gas supply device 421, but is connected to a supply port located relatively far from the modeling region R and is relatively inactive. Since the importance of active gas concentration management is low, it may not have a function of managing the concentration of inert gas. The fume collector 43 is, for example, an electric dust collector that applies charges to the fume 7 in the inert gas by corona discharge and collects the fume 7 by electrostatic attraction. The fume collector 43 has duct boxes 45 and 46 on the upstream side and the downstream side, respectively. The inert gas containing the fumes 7 discharged from the front chamber 11 is sent to the fume collector 43 through the duct box 45, and the clean inert gas 8 from which the fume 7 has been removed in the fume collector 43 is passed through the duct box 46. 11 sub supply ports 483. With such a configuration, the inert gas can be reused.

  As an inert gas supply system, as shown in FIGS. 1 and 2, a first inert gas supply device 421, a first supply port 481 and a second supply port 482 are connected to each other, and a second inert gas supply is provided. The device 422 and the driving chamber supply port 485 are connected to each other. Further, the fume collector 43 and the auxiliary supply port 483 are connected through the duct box 46. The first inert gas supply device 421 and the second inert gas supply device 422 are configured to supply a clean inert gas having a predetermined pressure and flow rate to the front chamber 11 and the control valve 27 by opening a predetermined amount through the control device 27. Each is supplied to the rear chamber 12. The inert gas supplied into the rear chamber 12 is supplied into the modeling chamber 111 through the communication portion 15 between the modeling chamber 111 and the driving chamber 121.

  In the additive manufacturing apparatus 1 of the embodiment, when the work door provided in the opening 115 is opened, the control device 27 opens the work door by a door detector that detects opening and closing of the work door (not shown). This is detected, and the first inert gas supply device 421 is stopped, but the second inert gas supply device 422 continues to supply the inert gas. When the work door is open, even if inert gas is supplied to the modeling chamber 111, it diffuses into the atmosphere. Therefore, supply of the inert gas to the modeling chamber 111 is stopped when the work door is open. By doing so, useless supply of inert gas can be suppressed.

  As shown in FIGS. 1 and 2, the fume discharge system includes a first discharge port 491, a second discharge port 492, a third discharge port 493, a fourth discharge port 494, a sub discharge port 495, and a fume collector 43. Each is connected through a box 45. The clean inert gas 8 after the fume 7 is removed in the fume collector 43 is returned to the front chamber 11 and reused.

  Here, the configuration of the fume collector 43 and the bypass 47 will be described in more detail with reference to FIG. The fume collector 43 includes a suction port 431 serving as a connection port with a fume discharge system, a suction unit 433 that sucks an inert gas including the fume 7 discharged from the front chamber 11, a fume collector body 440, and the fume 7. The exhaust part 435 which returns the removed inert gas in the front chamber 11 and the exhaust port 437 used as a connection port with an inert gas supply system are provided. The fume collector main body 440 is connected to the charging portion 442 in which a positively charged needle-shaped load electrode 443 and a counter electrode 444 connected to the ground are opposed to each other, and to a positive electrode plate 446 that is positively charged. A dust collecting device 441 having dust collecting portions 445 provided alternately with dust collecting plates 447 is provided. Preferably, the fume collector 43 further includes a fan motor 439 as a blower for efficiently circulating the inert gas inside the fume collector. In addition, the white arrow in FIG. 8 has shown typically the wind direction and flow volume of the airflow of an inert gas.

  A bypass 47 is provided so as to connect the suction part 433 and the exhaust part 435. The bypass 47 is configured such that the opening area between the suction portion 433 and the fume collector body 440 is larger than the opening area between the suction portion 433 and the bypass 47, and the opening area between the exhaust portion 435 and the bypass 47 is exhausted. The opening area between the portion 435 and the exhaust port 437 is configured to be larger. The larger the opening area, the lower the fluid resistance, so that an inert gas stream flowing from the exhaust part 435 to the suction part 433 is formed in the bypass 47. In the following, the flow of inert gas from the exhaust part 435 to the suction part 433 in the bypass 47 is referred to as bypass air flow.

  The fume discharge system is connected to the suction port 431 of the fume collector 43, and an inert gas containing the fume 7 is sent from the suction port 431 to the fume collector main body 440 through the suction part 433. In the dust collector 441 of the fume collector main body 440, the fume 7 contained in the inert gas is first charged positively by corona discharge generated between the load electrode 443 and the counter electrode 444 in the charging unit 442. When the positively charged fume 7 passes through the dust collecting portion 445, the fume 7 is repelled by the positive electrode plate 446 by the Coulomb force and collected by the dust collecting plate 447. The inert gas from which the fume 7 has been removed by the dust collector 441 is sent from the fume collector body 440 to the exhaust unit 435. At this time, a part or most of the inert gas becomes a bypass airflow and is returned to the suction unit 433 through the bypass. The inert gas returned to the suction part 433 is sent again to the fume collector body 440, and the above-described dust collection process is repeated. The remaining clean inert gas 8 that has not been returned to the suction portion 433 is sent to an inert gas supply system connected to the exhaust port 437, and passes through the duct box 46 from the sub supply port 483 to the front chamber. 11 is returned.

  With the above configuration, even if the flow rate of the inert gas circulating in the fume collector 43 is increased by the fan motor 439 or the like, the flow rate of the inert gas returned from the fume collector 43 to the chamber 10 is suppressed. A decrease in the inert gas concentration in the chamber 10 is suppressed.

  In the additive manufacturing apparatus 1 including the driving device 13 for performing the cutting process as in the additive manufacturing apparatus 1 of the embodiment, the chamber 10 becomes larger in order to install the driving device 13. As the chamber 10 becomes larger, the exhaust efficiency of the fumes 7 decreases. Therefore, in the additive manufacturing apparatus 1 including the driving device 13, the present invention that can efficiently remove the fumes 7 while maintaining the inert gas concentration is more useful.

  In this embodiment, both ends of the bypass 47 are connected to the suction part 433 and the exhaust part 435 of the fume collector 43, but the bypass 47 is on the side of the suction part 433 sent from the chamber 10 to the fume collector 43. The inert gas flow path may be provided so as to be connected to the inert gas flow path on the exhaust portion 435 side returned from the fume collector 43 to the chamber 10. For example, both ends of the bypass 47 may be configured to be connected to the sub supply port 483 and the sub discharge port 495 in the front chamber 11 of the additive manufacturing apparatus 1.

  Further, in this embodiment, the bypass airflow is formed by utilizing the fluid resistance difference, but the bypass airflow may be formed by other configurations. For example, mechanical bypass airflow forming means such as a blower may be further provided.

  The fume collector 43 is not limited to the configuration shown in this embodiment as long as it is a device that removes the fume 7 from the inert gas. For example, a thin metal wire may be used instead of the needle-shaped load electrode 443, or the fume 7 may be negatively charged in the charging unit 442.

  The present invention is not limited to the configuration of the embodiment shown in the drawings as some examples have been specifically shown, and various modifications or applications are possible without departing from the technical idea of the present invention. It is.

DESCRIPTION OF SYMBOLS 1 additive manufacturing apparatus 4 inert gas supply / exhaust apparatus 6 material powder layer 7 fume 10 chamber 25 laser irradiation apparatus 42 inert gas supply apparatus 43 fume collector 47 bypass 441 dust collector 433 suction part 435 exhaust part L laser beam R irradiation region

Claims (1)

Predetermined irradiation on a material powder layer formed by uniformly distributing metal material powder for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height in a sealed chamber A laser irradiation apparatus for forming a sintered layer by irradiating the region with laser light;
An inert gas supply / discharge device that supplies the inert gas to the chamber so that the chamber is always filled with an inert gas having a predetermined concentration or more and exhausts fumes out of the chamber;
The inert gas supply / discharge device includes:
An inert gas supply device for supplying an inert gas to the chamber;
A suction portion for sucking an inert gas containing fumes discharged from the chamber, a dust collector for removing fumes from the inert gas containing fumes, and an inert gas from which fumes have been removed are returned to the chamber. A fume collector comprising an exhaust part;
Connected to the suction part side and the exhaust part side, forms an air flow of inert gas from the exhaust part side to the suction part side, and limits the flow rate of the inert gas returned into the chamber to an appropriate amount and a bypass that, the only free,
The flow path between the chamber, the suction part and the exhaust part, the flow path from the suction part through the dust collector to the exhaust part, and the flow path in the bypass are opened simultaneously. An additive manufacturing apparatus characterized by comprising:

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