JP4857103B2 - Powder sintering additive manufacturing apparatus and powder sintering additive manufacturing method - Google Patents

Description

  The present invention relates to a powder sintering additive manufacturing apparatus and a powder sintering additive manufacturing method, and more specifically, irradiates a thin layer of powder material with laser light, scans in the X direction and Y direction, and thins the powder material. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder sintering additive manufacturing apparatus and a powder sintering additive manufacturing method that sinter layers and sequentially laminate the sintered thin layers to produce a three-dimensional structure.

  In recent years, there has been an increasing demand for modeling apparatuses capable of modeling functional test prototype parts and parts used in a small variety of products.

  There exist an optical shaping | molding apparatus, a powder sintering layered shaping apparatus, etc. as what satisfy | fills this request | requirement. In particular, powder sintering additive manufacturing equipment is one of the major features that enables the use of many types and tough materials, unlike optical modeling equipment that uses ultraviolet curable resins, and it has also improved market recognition. It is starting to be used for various purposes.

  Conventionally, a powder sintering additive manufacturing apparatus that is commercially available includes a laser beam emitting unit, a modeling unit, and a control unit.

  The laser beam emitting unit includes a laser light source, a galvanometer mirror that scans the laser beam emitted from the laser light source in the X direction and the Y direction, and a driver that controls the operation of the galvanometer mirror.

  The modeling unit includes a modeling container installed in the center and powder material containers installed on both sides thereof. In a modeling container, a thin layer of powder material formed on a part table is sintered by laser light irradiation to form a sintered thin layer, and the part table is moved downward to sequentially laminate the sintered thin layer. A three-dimensional structure is produced. The upper opening surface of the modeling container is referred to as a modeling area. In the powder material container, the powder material is stored on the feed table, and the feed table moves upward to supply the powder material. The upper opening surface of the powder material container is referred to as a powder material storage region.

  In addition, the powder material container and the modeling container have a heater, the powder material is preheated with the heater, the temperature is raised to the melting point in advance, and the temperature of the thin layer of the powder material is quickly raised by laser irradiation. And melted and sintered to obtain a sintered thin layer of uniform powder material.

  FIG. 8A shows a sintered region in one scan of laser light, and FIG. 8B shows a sintered thin layer formed by performing a plurality of scans. The laser beam has an intensity distribution similar to the normal distribution in the spot, has high energy at the center, and gradually becomes weaker as it goes to the periphery. Therefore, when performing multiple scans, the beam is used to make the laser irradiation uniform. About 1/3 of the diameter is overwritten.

The control unit lowers the part table by one thin layer, causes the recoater to carry out the powder material from the left powder material container, and causes the powder material to be supplied onto the part table to form a thin layer of the powder material. Next, a thin layer of powder material is selected by irradiating a laser light source and scanning laser light in the X and Y directions with a galvanometer mirror based on slice data (drawing pattern) of the three-dimensional structure to be produced. Is heated and melted and sintered to form a sintered thin layer. Next, the part table is lowered by one thin layer, the powder material is carried out from the powder material container on the right side by the recoater, and the powder material is supplied onto the sintered thin layer on the part table to form a thin layer of the powder material. Form. Next, the thin layer of powder material is selectively heated and sintered to form a sintered thin layer. By repeating these operations, the sintered thin layer is laminated to form a three-dimensional structure. Finally, the three-dimensional structure is cooled.
Japanese Patent No. 2620353 Additive Manufacturing Technical Data Optronics

  By the way, when the thin layer of the powder material is selectively heated and sintered, the moving distance of the laser beam (the length of the sintered region) is input. As a result, a mirror speed control signal as shown in FIG. 8A is supplied from the control unit to the driver, and an ON / OFF control signal of the laser light source is supplied as shown in FIG. The length of the sintered area in one scan is controlled to be approximately equal to the input value.

  In this case, the actual operation of the mirror is as shown in FIG. 8B due to the signal delay by the driver circuit and the mechanical operation delay by the motor. Accordingly, the moving distance of the laser beam, that is, the length of the sintered region is determined by the distance corresponding to the ON period of the mirror speed control signal and the distance corresponding to the mirror operation stop delay period. The laser off delay time shown in FIG. 8 (c) is set in advance by a timer, so that the laser off delay time can be matched with the mirror stop delay period. Accordingly, the ON / OFF control signal of the laser light source is turned on only during a period that is the sum of the ON period of the mirror speed control signal and the actual operation stop delay period of the mirror. The sintered region obtained in this way is shown in FIG. Moreover, the example which applied this method to the case where especially a short area | region is sintered is shown to Fig.10 (a)-(d).

  As shown in FIGS. 8 (a) and 8 (b), since the speed control signal is turned on and the mirror remains stopped for a certain period as shown in FIGS. 8A and 8B, the timer delays the irradiation of the laser light source by the laser on delay time. There are many. FIG. 11 shows the actual mirror speed and timing chart of the ON / OFF control signal of the laser light source when the above method is applied particularly to a case where a short region is sintered, and the obtained sintered region. Shown in a). In this case, it is assumed that the mirror speed control signal is turned off before the mirror moves at a constant speed. As a result, the state of the mirror speed falling during the stop delay period changes compared to the case of FIG. 8 in which the mirror speed control signal is turned off after the mirror moves at a constant speed. To do. Further, when the mirror speed control signal is turned off before the mirror moves at a constant speed as described above, sintering is performed as shown in FIGS. The manner in which the mirror speed rises during the rise delay period and the manner in which the mirror speed falls during the stop delay period vary depending on the distance. As described above, when the movement of the mirror in the rising delay period and the stop delay period varies depending on the distance to be sintered, the shape and the length of the sintered region can be increased even if the laser on delay time and the laser off delay time are constant. It becomes impossible to control. For this reason, as shown in FIG.11 (b), the change of the shape and length of a sintering area | region becomes remarkable, and the precision of a three-dimensional molded item will deteriorate.

  Further, even when the same length as the sintering distance shown in FIG. 11A is sintered, the state of the rise of the mirror speed during the rise delay period and the state of the drop of the mirror speed during the stop delay period are shown. If it fluctuates, the shape and the length of the sintered area cannot be controlled. For this reason, the precision of a three-dimensional structure will deteriorate.

  The present invention was created in view of the above problems of the conventional example, and even if the area where the powder material thin layer should be sintered is short, the shape of the sintered area in one scan becomes uniform, In addition, the present invention provides a powder sintering additive manufacturing apparatus and a powder sintering additive manufacturing method capable of accurately controlling the length of a sintered region.

  In order to solve the above problems, the present invention relates to a powder sintering additive manufacturing apparatus, a laser light source, a mirror that scans laser light emitted from the laser light source in the X direction and the Y direction, lighting of the laser light source, and A control device for controlling the turning-off and controlling the operation of the mirror, irradiating the thin layer of powder material with the laser light, scanning in the X direction and Y direction, and thin layer of the powder material Is a powder sintering additive manufacturing apparatus that sequentially laminates the sintered thin layers to produce a three-dimensional structure, and after the control device outputs a signal to start the operation of the mirror, When the operation speed of the mirror becomes constant, the laser light source is turned on and the control device outputs a signal to stop the operation of the mirror, or after the control device outputs a signal to stop the operation of the mirror The mirror Is characterized in that work speed turns off the laser source prior to reduction from the constant speed.

  That is, the mirror operates at a constant speed after the rise delay time with respect to the mirror operation start signal, and operates to stop after the stop delay time with respect to the mirror operation stop signal. When inputting the moving distance of the light, enter the length of the region to be sintered plus the distance corresponding to the rise delay time of the mirror operation and the distance corresponding to the stop delay time of the mirror operation, and The laser on delay time is set so that the laser light source is turned on only for a period corresponding to the length of the region to be sintered.

  Alternatively, the mirror operates at a constant speed after the rise delay time has elapsed with respect to the mirror operation start signal, and starts to decelerate after operating at a constant speed with respect to the mirror operation stop signal. It operates so as to stop after the lapse of time, and as the moving distance of the laser beam, the distance corresponding to the rise delay time of the mirror operation and the distance corresponding to the deceleration time of the mirror operation are set to the length of the region to be sintered. In addition to inputting the added distance and outputting a mirror operation stop signal following the period corresponding to the length of the region to be sintered, the operation speed of the mirror decreases from a constant speed. The laser on delay time and the laser off delay time are set so that the laser light source is turned on only for the previous arbitrary period.

  The present invention relates to a powder sintering additive manufacturing method, using the powder sintering additive manufacturing apparatus, irradiating a thin layer of powder material with laser light, scanning in the X direction and the Y direction, A powder sintering additive manufacturing method for sintering a thin layer and sequentially laminating the sintered thin layers to create a three-dimensional structure, and after outputting a signal to start the operation of the mirror, When the operation speed becomes constant, the laser light source is turned on, and at the same time as the control device outputs a signal to stop the operation of the mirror, or after outputting the signal to stop the operation of the mirror, the operation speed of the mirror Is characterized in that the laser light source is turned off before falling from the constant speed.

  According to the powder sintering additive manufacturing apparatus of the present invention, the irradiation energy of the laser beam supplied to the thin layer of the powder material per unit length in one scan is constant everywhere. For this reason, even when the sintered region is short, the width of the sintered region in one scan including the vicinity of the start point and the end point is constant, and the length of the sintered region can be easily controlled. Thereby, especially when producing a thin three-dimensional structure, an accurate three-dimensional structure can be prepared.

  Also, according to the powder sintering additive manufacturing method of the present invention, the energy of laser light irradiation supplied to the powder material thin layer per unit length in one scan is constant everywhere, especially when the sintering region is short However, the shape of the sintered region of the thin powder material layer in one scan becomes uniform, and the length of the sintered region can be easily controlled with high accuracy. Thereby, especially when producing a thin three-dimensional structure, an accurate three-dimensional structure can be prepared.

  Embodiments of the present invention will be described below with reference to the drawings.

(Description of powder sintering additive manufacturing equipment)
The powder sintering additive manufacturing apparatus according to the embodiment of the present invention includes a laser beam emitting unit, a modeling unit, and a control unit.

  FIG. 1A is a top view showing the configuration of the modeling unit 101 in the powder sintering additive manufacturing apparatus according to the embodiment of the present invention. FIG. 1B is a cross-sectional view taken along line I-I in FIG. 1A. FIG. 1B also shows a laser beam emitting unit 102 disposed above the modeling unit 101. ing.

  FIG. 2 is a diagram showing a detailed configuration of the laser beam emitting unit 102 according to the embodiment of the present invention.

  Below, the detail of each part is demonstrated in the powder sintering layered manufacturing apparatus which concerns on embodiment of invention.

(A) Configuration of Laser Light Emitting Unit 102 First, the configuration of the laser light emitting unit 102 will be described.

As shown in FIG. 2, the laser beam emitting unit 102 includes a laser light source 23 formed of a CO ₂ laser, a galvanometer mirror that scans the laser beam in the X direction, and a galvanometer mirror that scans the laser beam in the Y direction. Each of the optical system 21, the optical system 22 having a lens that moves in accordance with the movement of the laser light scanned in the XY directions, and adjusts the focal length of the laser light to the thin layer surface of the powder material, An XYZ driver 24 for operating the galvanometer mirror and transmitting an electrical signal for operating the lens of the optical system 22. Each galvanometer mirror of the optical system 21 and the lens of the optical system 22 are each operated by a dedicated motor.

  The XYZ driver 24 is controlled by the controller 25, and the laser light source 23 is also controlled by the controller 25 in the same manner. As the controller 25, for example, a computer having a CPU (Central Processing Unit) and a memory storing a control program can be used. The controller 25 will be described in detail with respect to its configuration and functions in the following control section.

  The laser light emitted from the laser light source 23 is scanned in the X and Y directions by mirror control by the controller 25, and selectively irradiates the powder material thin layer 15a formed on the part table 11 of the modeling unit 101. Yes. Furthermore, while the laser beam is scanned in the X and Y directions, the lens of the optical system 22 constantly moves and the focal length is adjusted so that the laser beam is focused on the surface of the thin film of powder material. Yes. The mirror control is performed based on slice data (drawing pattern) of a three-dimensional structure to be produced.

(B) Structure of modeling part 101 Next, the structure of the modeling part 101 is demonstrated.

  In the modeling part 101, as shown to Fig.1 (a), (b), the square cylindrical modeling container 11 by which a three-dimensional molded item is produced, and the square cylindrical 1st installed in the both sides And second powder material containers 12a and 12b.

  In the modeling container 11, a thin layer 15a of a powder material is formed on a part table (bottom plate) 13, and the thin layer 15a of the powder material is sintered by irradiation with laser light to form a sintered thin layer 15b. . Then, the part table 13 is moved downward to sequentially laminate the sintered thin layers 15b, thereby producing a three-dimensional structure.

  In the first and second powder material containers 12a and 12b, the powder material 15 is stored on the feed table (bottom plate) 14a or 14b, and the feed table (bottom plate) 14a and 14b is moved upward to supply the powder material 15. The remaining powder material 15 after the feed tables 14a and 14b are moved downward to form the thin layer 15a of the powder material is carried in.

  The upper opening surface surrounded by the inner wall of the modeling container 11 is referred to as a modeling region, and the upper opening surfaces surrounded by the inner walls of the first and second powder material containers 12a and 12b are stored in the first and second powder materials. This is called a region.

  In the modeling container 11, a part table 13 that can be moved up and down along the inner wall is installed. On the part table 13, the thin layer 15a of a powder material is formed one by one, and each thin layer 15a of a powder material is heated and sintered. Further, in the first and second powder material containers 12a and 12b, first and second feed tables 14a and 14b for moving up and down along the inner walls of the containers 12a and 12b and supplying the powder material 15 are installed, respectively. ing.

  The part table 13 and the first and second feed tables 14a and 14b are connected to a driving device (not shown) that moves the tables up and down.

  Further, as shown in FIG. 1B, a recoater (powder material transporting means) that moves along the surface of the first powder material storage area, the modeling area, and the second powder material storage area over the entire area. 16 is provided.

  The recoater 16 moves along the surface of the powder material container 14a or 14b and in contact with the surface of the powder material container 14a or 14b, whereby the powder material 15 accommodated on the first or second feed table 14a or 14b. And is supplied onto the part table 13, and the surface of the powder material 15 is leveled to form a thin layer 15 a of the powder material on the part table 13. Further, the remaining powder material 15 after forming the thin layer 15a of the powder material is carried into the second or first powder material container 12b or 12a while leveling the surface. The supply amount of the powder material 15 is determined by the rising amount of the first or second feed table 14 a or 14 b, and the thickness of the thin layer 15 a of the powder material is determined by the lowering amount of the part table 13.

  As powder material 15, nylon, polypropylene, polylactic acid, polyethylene (PE), polyethylene terephthalate (PET), polystyrene (PS), acrylonitrile / butadiene / styrene copolymer (ABS), ethylene / vinyl acetate copolymer (EVA), styrene / At least one selected from the group consisting of acrylonitrile copolymer (SAN) and polycaprolactone, or metal powder can be used.

(C) Configuration and Function of Control Unit The control unit includes the controller 25 of the laser light emitting unit 102 described above and a controller of the modeling unit 101 (not shown).

  The controller 25 of the laser beam emitting unit 102 controls ON (lighting) and OFF (lighting off) of the laser light source 23 and the operation of the mirror of the optical system 21 and the lens of the optical system 22. The controller of the modeling unit 101 controls the operation of the part table 13, the first and second feed tables 14 a and 14 b, and the operation of the recoater 16.

  Next, the function of the controller 25 of the laser beam emitting unit 102 will be described with reference to FIGS. 3 and 4 in the order of the modeling operation.

  FIG. 3 is a timing chart showing timings at which the mirror speed control signal (operation start and operation stop signal) and the lighting control signal and extinguishing control signal of the laser light source 23 are sent from the controller 25 to the XYZ driver 24. FIG. 4A shows the timing of sending the mirror speed control signal, and FIG. 4C shows the timing of sending the lighting control signal and extinguishing control signal of the laser light source 23. FIG. 3 (b) shows the actual movement of the mirror that operates in accordance with these signals, and FIG. 3 (d) shows the planar shape of the sintered region affected by the movement. 3A to 3C, the horizontal axis indicates time in arbitrary units.

  FIG. 4 is a diagram specifically showing a signal sent from the controller 25 for controlling ON / OFF of the laser light source.

  In the following description, the terms acceleration period, constant speed period, deceleration period, rise delay period, and stop delay period are used, but the term time may be used instead of the period.

  First, the controller 25 performs the following initial settings. That is, the slice data (drawing pattern), laser output (Peff), laser beam diameter, mirror scanning speed, and moving distance of laser light in each scan based on the slice data (corresponding to the acceleration period) of the three-dimensional structure to be produced A distance, a distance corresponding to a constant speed period, and a distance corresponding to a deceleration period, or a distance corresponding to a rising delay period, a distance corresponding to a stop delay period, and a distance to be sintered. In addition, the delay time (laser on delay time (Tdon) and laser off delay time (Tdoff)) of the laser light source ON / OFF control signal input with respect to the mirror speed control signal input, and the distance corresponding to that time, etc. Is stored in the data memory. As an example, the laser beam diameter is normally set in the range of 300 to 600 μm, the mirror scanning speed is set at 12.5 m / sec, the distance corresponding to the rising delay period is about 10 mm, and the distance corresponding to the stop delay period Is set at about 8 mm.

  When the initial setting is completed, the apparatus is operated according to the control program.

  As shown in FIG. 3A, a mirror speed control signal corresponding to the start of mirror operation is sent from the controller 25 to the XYZ driver 24 in accordance with a movement command for moving the mirror by an angle corresponding to the movement distance of each scan. . In this case, in any scanning, the starting point of the movement of the mirror is set so as to be located outside the boundary of the modeling object to be formed by a distance corresponding to the rising delay period.

  Next, the XYZ driver 24 sends a speed control signal according to the sent speed control signal, and activates a motor that operates the galvanometer mirror of the optical system 21. In this case, a signal delay in the driver circuit in the XYZ driver 24 and a mechanical operation delay due to the motor occur, and as shown in FIG. 3B, the galvanometer mirror has a small speed at first and then the galvanometer mirror. Gradually increases in speed, and reaches a constant operating speed with a delay of a predetermined time (rise delay time) with respect to the speed control signal.

  On the other hand, based on the laser on delay time (Tdon) data, a lighting control signal is sent from the controller 25 to the laser light source 23 as shown in FIG. The laser light source 23 lights up substantially following the lighting control signal. At this time, the operation speed of the mirror is constant.

In FIG. 3 (c), the lighting control signal is shown as one continuous pulse, but actually, as shown in FIG. 4, the lighting control signal usually has a pulse of 10 to 100 kHz. Used. Based on the laser output (Peff) data, the pulse amplitude (P) and the duty ratio (T _ON / T _CYC ) of the pulse are adjusted.

  Subsequently, the mirror rotates for a time corresponding to the set distance to be sintered. In accordance with this, the laser beam is irradiated onto the powder material, and the powder material in the region corresponding to the constant width of the laser beam diameter and the constant speed distance is sintered.

  Thereafter, a speed control signal corresponding to the stop of the mirror operation is sent from the controller 25 to the XYZ driver 24. In accordance with the speed control signal, the XYZ driver 24 sends an operation stop control signal to stop the motor that operates the galvanometer mirror of the optical system 21. In this case, a signal delay in the driver circuit in the XYZ driver 24 and a mechanical operation delay due to the motor occur, and as shown in FIG. 3B, the galvanometer mirror has a constant time constant speed with respect to the operation stop control signal. After operating, it decelerates rapidly and stops operating. If the laser light source is turned on after the operation stop control signal is sent, the distance that the laser beam moves until the mirror is completely stopped is the distance corresponding to the stop delay period.

  On the other hand, a turn-off control signal is sent to the laser light source 23 as shown in FIG. The laser light source 23 is turned off almost following the turn-off control signal.

  In this way, one scan is completed. The mirror has moved to the start of the next scan and is waiting for the next scan.

  As described above, according to the control method by the controller 25, the laser beam is irradiated only when the mirror is at a constant speed. Therefore, the laser beam supplied to the thin layer of the powder material per unit length in one scan. The energy of irradiation is constant everywhere. For this reason, as shown in FIG. 3 (d), the width of the sintered region in one scan including the start point and the vicinity of the end point is constant, and the length of the sintered region can be easily controlled.

  FIGS. 7A to 7C are timing charts showing a control method by the controller 25 when the sintered region is shortened to form a thin wall. FIG. 7D is a diagram showing a planar shape of a sintered region in one scan of laser irradiation corresponding to the timings of FIGS. 7A to 7C.

  This control method is also the same as the control method described in FIGS. 3A to 3D, and as shown in FIG. 7D, even when the sintering region is short, the powder material thin layer is sintered in one scan. The shape of the region is uniform. It turns out that this control method is particularly effective when the sintered area in one scan is shortened to form a thin wall. The difference is clear as compared with FIGS. 10A to 10D of the conventional example.

  Next, the function of the controller of the modeling unit 101 will be described below.

  The controller first raises the first feed table 14b on which the powder material is placed, lowers the part table 13 by one thin layer, moves the recoater 16, and moves the recoater 16 from the first powder material container 12a for modeling. The powder material 15 is supplied to the container 11, and a thin layer 15 a of the powder material is formed on the part table 13. After the second feed table 14b in the second powder material container 12b is lowered and the recoater 16 is moved while leveling the surface of the second powder material container 12b, the thin layer 15a of the powder material is formed. The remaining powder material 15 is stored on the second feed table 14b.

  After that, under the control of the controller 25 described above, based on the slice data (drawing pattern) of the three-dimensional structure to be produced, a thin layer of powder material is formed by the laser light, the mirror of the optical system 21 and the lens of the optical system 22. 15a is selectively heated and sintered.

  Contrary to the above, the second feed table 14b on which the powder material 15 is placed is raised, the part table 13 is lowered by one thin layer, and the recoater 16 is moved to move from the second powder material container 12b. The powder material 15 is supplied to the modeling container 11, and a new thin layer 15 a of powder material is formed on the thin layer 15 a of powder material on the part table 13. Then, the first feed table 14a in the first powder material container 12a is lowered, and the recoater 16 is moved while leveling the surface of the first powder material container 12a to form a thin layer 15a of a new powder material. After that, the remaining powder material 15 is stored on the first feed table 14a.

  After that, under the control of the controller 25 described above, based on the slice data (drawing pattern) of the three-dimensional structure to be produced, the thin layer 15a of the powder material is formed by the laser light, the mirror of the optical system 21 and the lens of the optical system 22. Are selectively heated and sintered.

  By repeating these operations, a plurality of sintered thin layers 15b are laminated to produce a three-dimensional structure.

  As described above, according to the powder sintering additive manufacturing apparatus according to the embodiment of the present invention, the width of the sintered area in one scan including the start point and the vicinity of the end point is constant, and the length of the sintered area is long. It becomes easy to control the thickness accurately. Thereby, an accurate three-dimensional structure can be produced. This is particularly effective when producing a thin three-dimensional structure.

(Description of powder sintering additive manufacturing method)
Next, a powder sintering additive manufacturing method using the powder sintering additive manufacturing apparatus will be described with reference to FIGS. 1 to 4 and FIG. 6. 6A and 6B are plan views showing a sintered region of a thin layer of a powder material formed by this powder sintering additive manufacturing method.

  First, specifications to be controlled are set in the control unit. Among these specifications, the scanning speed of the mirror is 12.5 m / sec in both the X direction and the Y direction. Further, the ON / OFF control signal of the laser light source 23 is a pulse having a frequency of 50 kHz, and the pulse amplitude and the duty ratio are set so that the effective power (Peff) is about 30 W. Also, the mirror rising delay time with respect to the speed control signal input corresponding to the start of the mirror operation is set to 1.2 msec (corresponding to about 10 mm as the moving distance), and the mirror is stopped with respect to the speed control signal input corresponding to the mirror operation stop. The delay time is 1 msec (corresponding to about 8 mm as the moving distance). Further, the laser on delay time is set to be the same as the mirror rising delay time, and the laser off delay time is set to zero.

  Next, in the modeling part 101, the left and right feed tables 14a and 14b are lowered, and a sufficient amount of the powder material 15 is stored on the feed tables 14a and 14b.

  Next, the part table 13 is lowered by an amount corresponding to one thin layer. Next, the left feed table 14a is raised so that the powder material 15 comes out from the surface of the first powder material container 12a. At this time, the feed table 14b on the right side is lowered, and the storage portion is left open so that the remaining powder material 15 after forming the thin layer 15a of the powder material can be stored.

  Next, the recoater 16 is moved and moved onto the left feed table 14 a and onto the part table 13 in the modeling container 11 while scraping the powder material 15 that has come up from the surface of the first powder material container 12 a. .

  Next, the powder material is carried onto the part table 13 while leveling the surface of the modeling container 11. Thereby, as shown in FIG. 1A, a thin layer 15 a of powder material for one layer is formed on the part table 13. At this time, the surface of the thin layer 15a of the powder material is powdered by a heater (not shown) installed on the inner wall of the modeling container 11 or an infrared heating device (not shown) provided obliquely above the modeling container 11. Preheat to a temperature about 5-15 ° C. below the melting point of the material.

  Further, the recoater 16 is moved to carry the remaining powder material 15 into the second powder material container 12b while leveling the surface, and accommodated on the second feed table 14b in the second powder material container 12b. .

  Next, a control signal composed of a pulse with a frequency of 50 kHz and having an effective power of about 30 W is sent from the controller 25 to the laser light source 23. As a result, laser light is emitted from the laser light source 23. Further, based on the slice data of the three-dimensional structure to be produced, the controller 25 controls the operation of the mirror of the optical system 21 and the lens of the optical system 22 to move the laser light in the X direction, thereby thin layer of powder material. 15a is irradiated with laser light. Thereby, the thin layer 15a of the powder material for one scanning (processing unit) is heated and sintered.

  At this time, as shown in FIG. 3, based on the set value of the delay time, the movement of the mirror is controlled, and the turning on and off of the laser light source 23 is controlled. As a result, the laser beam is applied to the thin layer 15a of the powder material only when the mirror is at a constant speed. Therefore, the irradiation of the laser beam supplied to the thin layer 15a of the powder material per unit length in one scan. Your energy will be constant everywhere. As a result, as shown in FIG. 3D, the shape of the sintered region 15b of the thin powder material layer in one scan becomes uniform.

  Next, this scanning is sequentially performed in the Y direction to sinter a predetermined region of the thin layer 15a of the powder material. FIG. 6 (a) shows a state after the predetermined region of the thin layer 15a of the powder material has been sintered. As shown in FIG. 6 (a), even if the sintered region 15b of the powder material thin layer in one scan is not overlapped much, unevenness is reduced at the boundary between the sintered region and the non-sintered region. Can be smoothed. In addition, in order to further reduce the unevenness at the boundary and smooth the boundary after this, as shown in FIG. 6B, the edge is irradiated with laser light along the uneven boundary in the Y direction. It is good to do.

  Next, the part table 13 is lowered by one thin layer, the second feed table 14b is raised, and the first feed table 14a is lowered.

  Next, contrary to the case described above, the recoater 16 is moved from the right side to the left side. Then, a new powder material 15 is supplied from the second powder material container 12b onto the part table 13, and a new powder material thin layer is formed on the sintered thin layer 15b.

  Further, the recoater 16 is moved to carry the remaining powder material 15 into the first powder material container 12a while leveling the surface, and accommodated on the first feed table 14a in the first powder material container 12a. .

  Next, a thin layer of a new powder material on the sintered thin layer 15b is heated and sintered to form a new sintered thin layer on the sintered thin layer 15b. That is, based on FIG. 3, the movement of the mirror is controlled to control when the laser light source is turned on and off. In this case, unlike the case of the first layer in which the laser beam is scanned in the X direction, it is desirable to scan the laser beam in the Y direction. This is because the internal stress is reduced in the completed three-dimensional structure so that the shape of the structure is not distorted.

  Next, the part table 13 is lowered by one thin layer by the above-described method, the first feed table 14a is raised, and the second feed table 14b is lowered.

  Next, the formation of the thin layer 15a of powder material → heating and sintering → formation of the thin layer 15a of powder material → heating and sintering are repeated by the method described above.

  In this way, the sintered thin layer 15b is sequentially laminated to complete a three-dimensional structure. Finally, the preliminary heating is stopped and natural cooling is performed. When the temperature reaches around room temperature, the three-dimensional structure buried in the powder material 15 is taken out of the modeling container 11.

  As described above, according to the powder sinter layered manufacturing method according to the embodiment of the present invention, the shape of the sintered region of the powder material thin layer in one scan is uniform, so the powder material thin layer in one scan Even if the sintered regions do not overlap much, the unevenness can be reduced at the boundary between the sintered region and the non-sintered region, and the boundary can be made smooth. For this reason, an accurate three-dimensional structure can be produced.

(Description of another embodiment of the present invention)
The powder sintered additive manufacturing apparatus and the powder sintered additive manufacturing method of the present invention have been described above in detail according to the embodiment, but the scope of the present invention is not limited to the examples specifically shown in the above embodiment. Without departing from the spirit of the present invention, the modifications of the above embodiment are included in the scope of the present invention.

  For example, in the above-described embodiment, the modeling method of the present invention is applied to the entire thin film of the powder material, but the sintering target region is particularly short among the entire sintering target. The modeling method of the present invention may be selectively applied only to places where accuracy is required.

  In the above embodiment, the delay time of the ON / OFF control signal input of the laser light source with respect to the mirror speed control signal input is set in advance. This is applicable if the delay time is known in advance, but if it is not known, the speed of the mirror is detected and fed back to the controller 25 to The laser light source ON / OFF control signal may be input at a specific mirror speed at which the shape does not collapse so much.

  In addition, the laser light source is turned off in accordance with the timing at which the control device outputs a mirror operation stop signal. As shown in FIGS. 5A to 5C, the control device outputs a mirror operation stop signal. After the output, the laser light source may be turned off before or just before the operation speed of the mirror decreases from a constant speed. As a result, as shown in FIG. 5D, similarly to FIG. 3D, a uniformly shaped sintered region is formed.

  Furthermore, the set values of the specifications to be controlled by the controller 25 can be changed as appropriate within the range where the object of the present invention can be achieved, in addition to the values described above.

  In the embodiment, when a plurality of scans are performed, overwriting is performed with less than 1/3 of the beam diameter. However, it is preferable to overwrite about 1/3 of the beam diameter in order to make the laser irradiation amount uniform.

(A) is a top view which shows the structure of a modeling part among the powder sintering lamination-modeling apparatuses which are embodiment of this invention, (b) is sectional drawing which follows the II line | wire of (a). . It is a figure which shows the structure of the laser beam emission part in the powder sintering layered modeling apparatus of FIG. (A) is a timing chart which shows the timing of application of the speed control signal of a mirror in the powder sintering additive manufacturing method using the powder sintering additive manufacturing apparatus of FIG. 1, (b) is also a speed control signal. 6 is a timing chart showing the actual operation of the mirror based on the above, (c) is a timing chart showing the application timing of the ON / OFF control signal of the laser light source, and (d) is a timing chart of (a) to (c). It is a figure which shows the planar shape of the sintering area | region in one scan of laser irradiation formed with the timing of (). FIG. 2 is a diagram specifically illustrating a signal for controlling ON / OFF of a laser light source in the powder sintered additive manufacturing apparatus of FIG. 1. (A)-(c) is a timing chart at the time of setting a laser off delay time with respect to FIG. 3 (a)-(c), (d) is based on the timing of (a)-(c). It is a figure which shows the planar shape of the sintering area | region in one scan of formed laser irradiation. (A), (b) is a top view which shows the sintering area | region of the thin layer of the powder material formed by this powder sintering layered manufacturing method. (A)-(d) is a timing chart and figure corresponding to the timing chart and figure of Drawing 3 (a)-(d) in the case where a sintering object field is short. (A) is a timing chart which shows the application timing of the speed control signal of a mirror in a prior art example, (b) is a timing chart which similarly shows the actual operation | movement of a mirror based on a speed control signal, (c) FIG. 6 is a timing chart showing the application timing of the laser light source ON / OFF control signal, and FIG. 4D is a diagram of laser irradiation corresponding to the application timing of the laser light source ON / OFF control signal. It is a figure which shows the planar shape of the sintering area | region in a scan. It is a top view which shows the sintering area | region of the thin layer of the powder material formed by the powder sintering additive manufacturing method of a prior art example. (A)-(d) is a timing chart and figure corresponding to the timing chart and figure of FIG. 7 (a)-(d) in the case where a sintering object area | region is short in a prior art example. (A) is the timing chart and figure corresponding to the timing chart and figure of Drawing 10 (b)-(d) at the time of setting a laser on delay time to Drawing 10 (c) in a conventional example. (B) is the timing chart and figure corresponding to the timing chart and figure of Drawing 10 (b)-(d) in case the length of a sintering field is still shorter than the above (a).

Explanation of symbols

11 Modeling container 12a First powder material container 12b Second powder material container 13 Part table 14a First feed table 14b Second feed table 15 Powder material 15a Thin layer 15b of powder material Sintered thin layer 16 Recoater 21 , 22 Optical system 23 Laser light source 24 XYZ driver 25 Controller 101 Modeling unit 102 Laser beam emitting unit

Claims (4)

A laser light source, a mirror that scans the laser light emitted from the laser light source in the X direction and the Y direction, and a control device that controls turning on and off of the laser light source and controlling the operation of the mirror, A thin layer of powder material is irradiated with the laser beam, scanned in the X direction and Y direction, the thin layer of powder material is sintered, and the sintered thin layer is sequentially laminated to form a three-dimensional structure. A powder sintering additive manufacturing apparatus for producing
The controller, after outputting a signal for starting the operation of the mirror, turns on the laser light source when the operation speed of the mirror becomes constant, and at the same time the controller outputs a signal for stopping the operation of the mirror. Alternatively, after the control device outputs a signal to stop the operation of the mirror, the laser light source is turned off before the operation speed of the mirror decreases from the constant speed. . The mirror operates at a constant speed after the rise delay time with respect to the operation start signal of the mirror, and operates to stop after the stop delay time with respect to the operation stop signal of the mirror,
In the control device, as the moving distance of the laser beam, a distance corresponding to the rise delay time of the mirror operation and a distance corresponding to the stop delay time of the mirror operation are added to the length of the region to be sintered. 2. The laser on-delay time is set so that the laser light source is turned on only for a period corresponding to the length of the region to be sintered. Powder sintering additive manufacturing equipment. The mirror operates at a constant speed after a rise delay time has elapsed with respect to the operation start signal of the mirror, and starts to decelerate after operating at the constant speed with respect to the operation stop signal of the mirror. Works to stop after time,
In the control device, as the moving distance of the laser beam, a distance corresponding to the rising delay time of the mirror operation and a distance corresponding to the deceleration time of the mirror operation are added to the length of the region to be sintered. In addition to a period corresponding to the length of the region to be sintered, after inputting a distance, the operation speed of the mirror decreases from a constant speed after outputting a signal to stop the operation of the mirror following that period. 2. The powder sintered additive manufacturing apparatus according to claim 1, wherein the laser on-delay time and the laser off-delay time are set so that the laser light source is lit only for an arbitrary period before the start. Using the powder sintering additive manufacturing apparatus according to claim 1, the thin layer of the powder material is irradiated with laser light, scanned in the X direction and the Y direction, the thin layer of the powder material is sintered, and the sintering is performed. It is a powder sintering additive manufacturing method in which a thin layer is sequentially laminated to create a three-dimensional object,
After outputting the operation start signal of the mirror, the laser light source is turned on when the operation speed of the mirror becomes constant, and at the same time as the control device outputs the operation stop signal of the mirror, or the mirror After outputting the operation stop signal, the laser light source is turned off before the operation speed of the mirror decreases from the constant speed.

Images