JP3170486B2 - Additive manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a three-dimensional object by laminating a cured layer.

[0002]

2. Description of the Related Art The additive manufacturing method is used as a method for forming a three-dimensional object having a complicated shape in a short time. The three-dimensional object created by the additive manufacturing method is used as a model (prototype) of a component of various devices to check the operation and shape of the component.

[0003] As a lamination molding method, a photocurable resin,
There is a method of using a coagulant (thermoplastic resin, wax or the like) for solidifying the periphery of the photocurable resin, and laminating a cured layer composed of the photocurable resin and the coagulant.

[0004]

In the conventional additive manufacturing method, there is a tendency that the thermal expansion coefficient of the coagulant is considerably larger than the thermal expansion coefficient of the photocurable resin. There is also a problem that when heated, the coagulant expands and destroys the three-dimensional object composed of the photocurable resin.

The present invention has been made to solve the above-mentioned problems in the prior art, and reduces the possibility of destruction of an object made of a photocurable resin when a molded laminate is heated. The purpose is to provide a technology that can do it.

[0006]

Means for Solving the Problems and Their Functions and Effects In order to solve the above-mentioned problems, the additive manufacturing method according to the present invention is a method for modeling a three-dimensional object by laminating a cured layer. ) To apply photocurable resin
Therefore, the first tree having a desired planar shape and a predetermined thickness
Forming a resin layer region ; and (B) the first resin layer region.
Forming a first cured layer region by irradiating the region with light to form a first cured layer region; and (C) a mixture of urea and polyvinyl alcohol and a eutectic compound, Using a mixture having a coefficient of thermal expansion approximately equal to the coefficient of thermal expansion, a second cured layer region is formed around the first cured layer region, whereby the first and second cured layer regions are formed. Forming a hardened layer to be configured;
(D) a step of laminating the cured layer by repeating the steps (A) to (C) .

In the above method, since the thermal expansion coefficients of the mixture and the photocurable resin are almost equal, when the molded laminate is heated, the object composed of the photocurable resin is broken by the expansion of the mixture. Is unlikely.

[0008]

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a three-dimensional object modeling system 10 according to a first embodiment of the present invention.
FIG. This three-dimensional object modeling system 1
Reference numeral 00 denotes a graphic workstation 200 and a modeling apparatus 300.

Graphic workstation 200
Creates cross-sectional vector data representing a cross-sectional shape of a three-dimensional object based on data representing the shape of the three-dimensional object, and converts the generated cross-sectional data into a three-dimensional object modeling system 10.
Supply 0. Note that a method of creating data representing the cross-sectional shape of an object from CAD data is well known in the field of CAD (computer-aided design). For example, a Quantum1 system commercially available from Scitex Corp. Is realized by the plot function. The method and apparatus for creating data representing the cross-sectional shape of an object are described in JP-A-63-72526 and JP-A-2-78531, and the details are omitted here.

The molding apparatus 300 is constituted by the following subsystems. (A) Table section 10: The table section 10 includes a table 12 on which the stacked body LS being formed is placed, and a motor 14 for moving the table 12 in the vertical direction. The table unit 10
Further, a position detecting device (not shown) for detecting the absolute position of the table 12 in the vertical direction is provided. Motor 1
In step 4, the table 12 is lowered downward by the height of the object every time the object is formed by a predetermined height.

(B) Coagulant application section 20: a unit for applying a coagulant to the surface of the laminate LS, a tank 22 for storing a liquid coagulant, and a coagulant for applying the coagulant to the surface of the laminate LS And the application head 24 of the above. The coating head 24 has an elongated coating port that extends over the width of the laminate LS in the X direction (the direction perpendicular to the paper surface). The coating head 24 is engaged with the rail 16 extending in the Y direction, and is driven by a motor (not shown) to move in the Y direction. As the coagulant, a urea-based mixture described in JP-A-2-55638 is used.

The above-mentioned urea-based mixture is a urea-based mixture obtained by adding polyvinyl alcohol and a eutectic compound to urea. A eutectic compound is a compound that eutectically melts with urea at a low temperature and significantly lowers the melting point or freezing point of the eutectic, such as benzoic acid, benzenesulfinic acid, benzenesulfonic acid,
Benzoyl chloride, glycine, naphthalene, glutaric acid and the like are used. The urea-based mixture has a melting point of about 1
20 ° C., the coefficient of linear expansion is about 10 ⁻⁴ / ° C. Since the melting point of this urea-based mixture is higher than room temperature, it is maintained in a molten state by heating with a heater 26 provided around the tank 22. The details of the production method and physical properties of the urea-based mixture are described in the above-mentioned JP-A-2-55638.
Therefore, the details are omitted here.

(C) Cooling roller 30: A roller for cooling and completely hardening the coagulant applied to the surface of the laminate LS. The cooling roller 30 is also engaged with the rail 16, and is driven by a motor (not shown) to move in the Y direction.

(D) Laser cutting section 40: As shown in FIG. 2, a YAG laser 42, a beam expander 44,
A pair of reflecting mirrors 46 and 47 and a focusing unit 48
have. The pair of reflection mirrors 46 and 47 and the focusing unit 48 are mounted on a moving table 49 engaged with the rail 16 (FIG. 1). The moving table 49 is driven by a first motor (not shown) and moves in the Y direction. The mirror 47 and the focusing unit 48 are driven by a second motor (not shown) and move integrally in the X direction. The laser 42 is controlled by a pulse width control unit (not shown), and the pulse width is adjusted so that the energy of light spots on the surface of the stacked body per unit process becomes equal.
The laser cutting section 40 is used to remove a desired region of the hardened coagulant formed on the surface of the laminate LS.

(E) Resin application section 50: It is composed of a tank 52 for storing the photocurable resin and an application head 54 for applying the photocurable resin to the surface of the laminate LS. The coating head 54 has an elongated coating port extending over the width of the laminate LS in the X direction. The coating head 54 is engaged with the rail 16 extending in the Y direction, and is driven by a motor (not shown) to move in the Y direction. The photocurable resin preferably has a glass transition point higher than the melting point of the urea-based mixture described above. This is to prevent the cured photocurable resin from softening when a molten urea-based mixture (coagulant) is applied on the photocurable resin in a step described later.

As the photo-curable resin, for example, urethane-based acrylate Desolite KC1003 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd. can be used.
This photocurable resin has a glass softening point of about 150 ° C. and a coefficient of linear expansion of about 10 ⁻⁴ / ° C.

(F) Light irradiation unit 60: a unit for generating light for curing the photocurable resin. The light irradiation unit includes a light source and a motor (not shown) that moves the light source along the rail 16. When using an ultraviolet curable resin as the photocurable resin, use various ultraviolet light sources such as a so-called quartz low-pressure mercury lamp, a deuterium lamp, a germicidal lamp, a photopolymerization lamp, and a black light lamp. Can be. These light sources are less expensive than ultraviolet lasers, and light sources that emit light in a desired wavelength range for curing the photocurable resin can be selected. When a visible light curable resin is used, the resin is cured by irradiating visible light for several tens of seconds, so that a blue fluorescent lamp, a metal halide lamp, or the like can be used as a light source. Note that these light sources can provide more energy than lasers,
There is also an advantage that the photocurable resin can be completely cured in a shorter time.

(G) Control unit 70: Controls the laser cutting unit 40 according to the cross-sectional vector data of the three-dimensional object supplied from the graphic workstation 200, and controls other units in the modeling apparatus 300. The cross section vector data is generated for each predetermined height position of the three-dimensional object to be formed.

FIG. 3 is a process sectional view showing a procedure for manufacturing a three-dimensional object by the three-dimensional printing system 100.
In the step of FIG. 3A, the application head 24 of the coagulant application section 20 uniformly applies the coagulant SL on the surface of the laminate LS, thereby forming a coagulant layer SLL having a predetermined thickness. The thickness of the coagulant layer SLL is about 25 μm to about 100 μm.
m is preferred.

The laminated body LS has a plurality of cured layers L1, L
2 has a laminated structure. Each cured layer L1, L2
Is composed of a resin region PAR made of a photocurable resin and a coagulant region SLR made of a coagulant.

In the step of FIG. 3B, the cooling roller 30 cools the coagulant layer SLL to solidify the coagulant SL. The coagulant SL is naturally cooled to a certain degree before being cooled by the cooling roller 30, but is completely cured by being cooled by the cooling roller 30.

In the step of FIG. 3C, the laser cutting unit 40
Thereby, desired regions R1 and R2 of the coagulant layer SLL are cut. At this time, the energy of the laser 42 is adjusted so that the thickness of the layer to be cut is at least the thickness of the coagulant layer SLL. When the laser light is irradiated, the coagulant SL
Evaporates (sublimates) and disappears. At this time, the coagulant layer SLL
In order not to cut the resin region PAR below, it is preferable to use a coagulant having a sublimation temperature lower than that of the photocurable resin.

In the step shown in FIG. 3D, the region R where the coagulant has been cut by the coating head 54 of the resin coating section 50 is used.
1, R2 is filled with a photocurable resin PA. A doctor blade 56 is provided at the rear end of the coating head 54, and unnecessary photocurable resin PA is wiped off by the doctor blade 56. Instead of using the coating head 54, the regions R1 and R2 are filled with the photocurable resin by discharging the photocurable resin PA from a nozzle that moves two-dimensionally on the XY plane. It may be. If such a nozzle is used, the photocurable resin can be used without waste, and the photocurable resin can be prevented from adhering to the side surface of the multilayer body LS.

In the step shown in FIG. 3E, the light irradiating section 60 irradiates the surface of the laminate LS with light to cure the photocurable resin PA. As a result, the three cured layers L1, L
A laminated body LS composed of L2 and L3 is formed.

The photocurable resin is characterized in that the activity decreases when the surface is cut after curing, and the adhesive strength is weakened even when the photocurable resin is cured. However, FIG.
Since the surface of the photo-curable resin included in the cured layer L2 is not cut in the step of, there is an advantage that the photo-curable resins of the two cured layers L2 and L3 are firmly adhered to each other. Further, in the step of FIG. 3C, since the coagulant SL is not mechanically cut with a blade or the like, the powder of the coagulant SL does not remain on the photocurable resin of the cured layer L2. Therefore, the photocurable resin of the cured layer L2 adheres more strongly to the photocurable resin of the cured layer L3.

By repeating the steps of FIGS. 3A to 3E, the cured layers are sequentially laminated to form a desired laminated body LS. After the completion of the laminate LS, the three-dimensional object composed only of the photocurable resin PA is obtained by removing the coagulant SL by heating it to a temperature equal to or higher than the melting point of the coagulant SL (about 120 ° C.). Can be The melting point of the urea-based mixture used as the coagulant SL is about 120 ° C, and the glass transition point of the photocurable resin PA is about 150 ° C. The resin PA does not soften excessively. The linear expansion coefficient of the urea mixture is about 10 ^-4 / ° C, and the linear expansion coefficient of the photocurable resin is about 1
Since it is 0 ^-4 / ° C., even when the laminate LS is heated to about 120 ° C. or more, the urea-based mixture does not expand excessively and does not compress the photocurable resin to be deformed. Obtainable.

Since the urea-based mixture is easily dissolved in water, it is possible to obtain an object composed only of a photocurable resin by dissolving the mixture in water. However, if the urea-based mixture is heated and dissolved, there is an advantage that the urea-based mixture can be reused as a coagulant for the coagulant application unit 20.

As the coagulant for the coagulant applying section 20, it is also possible to use a thermoplastic engineering plastic (acrylic resin, ABS resin, or the like) melted by heating or polyethylene glycol (carbowax) melted by heating. If an engineering plastic is used, an object made of the engineering plastic can be obtained by removing the photocurable resin portion of the laminate LS. In this case, there is an advantage that a plastic can be selected and shaped according to the use of the final object.

B. FIG. 4 shows a second embodiment of the present invention.
It is a conceptual diagram which shows the shaping apparatus 300a of the rotation system as an Example of FIG. The shaping apparatus 300a includes a cylindrical turntable 8
0, and the stacked body LS is formed on the turntable 80. Above the turntable 80, a coagulant application section 20 is provided. Further, a cooling roller 30 is provided on the upper right side of the turntable 80, a laser processing section 40 is provided on the right side, and a resin application section 50a is provided below. On the left side, a light irradiation unit 60 is provided. Note that the control unit 70 is omitted in FIG.

Below the laser processing section 40, there is provided a suction device 41 for sucking the coagulant vaporized by the irradiation of the laser beam. In addition, such a suction device 41
May be provided in the modeling apparatus 300 of FIG.

The resin application section 50a provided below the turntable 80 includes a tank 52 for storing the photocurable resin, an application roller 55 for applying the photocurable resin to the surface of the laminate LS, And a doctor blade 56 for wiping unnecessary photocurable resin on the surface of the body LS.

In the molding apparatus 300a shown in FIG.
While rotating clockwise at a constant peripheral speed, the laminate LS is formed according to the same process as in FIG. In the example of FIG.
The stacked body LS is formed at four positions on the turntable 80. Thus, in this modeling apparatus 300a, a plurality of laminates L
S can be simultaneously formed. As the thickness of the stacked body LS increases, a moving mechanism (not shown) that moves each part away from the center axis of the turntable 80 as shown by arrows is provided in each part.

In the molding apparatus 300a, since the surface of the laminate LS is continuous, the coagulant can be uniformly applied by the coagulant applying section 20, and the resin applying section 5
0a has the advantage that it is easy to apply the photocurable resin uniformly. Further, there is an advantage that a plurality of stacked bodies LS can be simultaneously formed.

C. Third Embodiment: When the urea-based mixture described above is used as a coagulant, a laminate can be further formed by the following various methods.

FIG. 5 is a process sectional view showing a second shaping method when a urea mixture is used as a coagulant. FIG.
In the step (A), the photocurable resin PA
To apply the photocurable resin PA to a desired region on the surface of the laminate LS. In the step of FIG. 5B, the light irradiating section 420 irradiates the photocurable resin PA with predetermined light to cure the resin. In the step of FIG. 5C, the coagulant applying section 430
However, a coagulant S is applied to the area around the cured photocurable resin PA.
Apply L. Then, in the step of FIG. 5D, the cooling roller 440 cools and solidifies the coagulant SL. FIG.
In the step (E), the rotary cutting unit 450 mechanically cuts the uppermost hardened layer L3 to a predetermined thickness, and the powder suction unit 452
Aspirates the cut powder. By repeating the steps of FIGS. 5A to 5E, a laminated body LS including an object having a desired shape made of a photocurable resin is obtained.

FIG. 6 is a process sectional view showing a third shaping method when a urea-based mixture is used as a coagulant. FIG.
In the step (A), the stacked body LS is held upside down by a holding device (not shown), and the lower surface thereof is immersed in a tank 460 that stores the photocurable resin PA.
In the step of FIG. 6B, the laser irradiation unit 470
A laser beam is irradiated from below 60 toward a desired region on the lower surface of the stacked body LS. As a result, the photocurable resin PA existing between the lower surface of the laminate LS and the inner bottom surface of the tank 460 is cured. Note that the bottom surface of the tank 460 is formed of a light transmitting member such as glass so as to transmit laser light. In the step of FIG. 6C, the stacked body LS is
The photocurable resin PA cured in the step shown in FIG. 6B is turned to the state where it comes to the upper surface of the laminate LS. In the step of FIG. 6 (D), the coagulant applying section 430 applies a liquid coagulant SL to a region around the photocurable resin PA, and the cooling roller 440 cools and coagulates the coagulant SL. In the step of FIG. 6E, the rotary cutting section 450 mechanically cuts the uppermost hardened layer L3 to a predetermined thickness, and the powder suction section 452 sucks the cut powder. FIG.
By repeating the step (E), a laminate LS including an object of a desired shape made of a photocurable resin is obtained.

FIG. 7 is a process sectional view showing a fourth molding method when a urea-based mixture is used as a coagulant. FIG.
In the step (A), the powder dispersion unit 480 deposits the powdered coagulant SL on the laminate LS to a predetermined thickness. FIG.
In the step (B), the laser irradiation unit 490 irradiates the laser light to the powdery coagulant SL deposited in the regions NR1, NR3, and NR3 to melt the coagulant SL. These regions NR1, NR2, and NR3 are regions excluding regions R1 and R2 (see FIG. 3) in which photocurable resin PA is filled. At this time, whether or not the coagulant in the regions NR1, NR2, and NR3 has been melted is imaged on the monitor 492 to check. FIG. 7 (C)
In the step, the molten coagulant SL is solidified by the cooling fan 500 and the unmelted coagulant SL
Blow off. As a result, the same structure as the stacked structure shown in FIG. Thereafter, the same steps as those shown in FIGS. 3D and 3E are performed, and a desired stacked body LS is obtained.

In some cases, the unmelted coagulant SL is not easily blown off. In such a case, FIG.
By repeating the steps of FIGS. 7A and 7B without performing the steps of FIG. 3C and the steps of FIGS. Objects can be shaped.

The urea-based mixture described above can be used for various additive manufacturing methods other than those described above. For example, JP-A-63-72526 and JP-A-2-78.
In the additive manufacturing method described in JP-A-531, it is possible to use as a material instead of carbowax (polyethylene glycol). At this time, as the photocurable resin, a resin having a glass transition point equal to or higher than the melting point of the urea-based mixture is preferable.

In the molding method described in JP-A-3-158228 or JP-A-4-59231, the above-mentioned urea-based mixture can be used as a coagulant discharged from a nozzle.

The present invention is not limited to the above-described embodiment, but can be implemented in various modes without departing from the gist of the invention.

[0042]

As described above, according to the present invention,
Since the thermal expansion coefficients of the mixture and the photocurable resin are almost equal, when the molded laminate is heated, there is an effect that an object made of the photocurable resin is less likely to be broken by the expansion of the mixture. is there.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a three-dimensional object modeling system according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a laser processing unit 40.

FIG. 3 is a process sectional view showing a procedure for manufacturing a three-dimensional object according to the present invention.

FIG. 4 is a conceptual diagram showing a rotary molding apparatus 300a as a second embodiment of the present invention.

FIG. 5 is a process cross-sectional view showing a second modeling method using a urea-based mixture as a coagulant.

FIG. 6 is a process sectional view showing a third shaping method using a urea-based mixture as a coagulant.

FIG. 7 is a process cross-sectional view showing a fourth shaping method using a urea-based mixture as a coagulant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Table part 12 ... Table 14 ... Motor 16 ... Rail 20 ... Coagulant application part 22 ... Tank 24 ... Application head 26 ... Heater 30 ... Cooling roller 40 ... Laser cutting part 41 ... Suction device 42 ... Laser 46, 47 ... Reflection Mirror 44 beam expander 48 focusing unit 49 moving table 50 resin coating unit 52 tank 54 coating head 55 coating roller 56 doctor blade 60 light irradiating unit 70 control unit 80 turntable 200 graphic Workstation 300: Modeling device 410: Nozzle 420: Light irradiation unit 430: Coagulant coating unit 440: Cooling roller 450: Rotating cutting unit 452: Powder suction unit 460: Tank 470: Laser irradiation unit 480: Powder spraying unit 490: Laser Irradiation unit 492 Monitor 500 Cooling fan L1 3: Cured layer LS: Laminated body NR1: Area not filled with photocurable resin PA: Photocurable resin PAR: Resin area R1, R2: Area filled with photocurable resin SL: Coagulant SLL: Coagulant layer SLR ... Coagulant area

Claims (1)

(57) [Claims] 1. A method of forming a three-dimensional object by laminating a cured layer, comprising the steps of: (A) applying a photocurable resin to form a first plate having a desired planar shape and a predetermined thickness ; Forming a resin layer region ; and (B) irradiating the first resin layer region with light to cure the first resin layer region.
By step and, (C) substantially equal thermal expansion coefficient as the thermal expansion rate of the photocurable resin a mixture obtained by adding a polyvinyl alcohol and a eutectic compound urea to form a first cured layer region Using the mixture having
Forming a second hardened layer region around the hardened layer region, thereby forming a hardened layer composed of the first and second hardened layer regions; and (D) the step (A) A step of laminating the cured layer by repeating steps (C) to (C) .