JP2023149055A - Optical molding apparatus - Google Patents

Abstract

To facilitate detachment of a plate from a molded object and to improve a dimensional accuracy of the molded object, in an optical molding apparatus.SOLUTION: An optical molding apparatus 1 includes: a transparent plate 2 having a surface that comes into contact with a material liquid M in which a powder material is suspended in a liquid photocurable resin; a light irradiation device 3 that cures the photocurable resin and forms a molded article by irradiating the material liquid with light through the plate; and a holder 4 that is movable relative to the plate and holds the molded article. The plate includes: a glass plate 31; a transparent silicone rubber layer 32 provided on the surface of the glass plate; and an amorphous fluororesin layer 33 provided on the surface of the transparent silicone rubber layer. The amorphous fluororesin layer comes into contact with the material liquid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a stereolithography apparatus.

In recent years, as a sustainable manufacturing technology, research and development has been carried out on three-dimensional printing devices, so-called 3D printers, which enable manufacturing on a small scale and with little waste generation. Patent Document 1 discloses that the photocurable resin is irradiated with light through a material tank into which a liquid photocurable resin mixed with metal powder is supplied and a transparent plate provided at the bottom of the material tank, and the photocurable resin is photocured. The present invention discloses a stereolithography apparatus that includes a light irradiation device that cures a plastic resin to form a modeled object, and a holder that holds the modeled object.

International Publication No. 2021/005858

The plate is required to have high light transmittance, easy peeling of the cured photocurable resin, and low scattering of light. If there is a lot of light scattering, the range of the light irradiated onto the photocurable resin becomes wider, causing a problem that the dimensional accuracy of the molded object decreases.

In view of the above background, it is an object of the present invention to facilitate the separation of a plate and a modeled object and to improve the dimensional accuracy of the modeled object in a stereolithography apparatus.

In order to solve the above problems, an embodiment of the present invention is a stereolithography apparatus (1), which has a surface that is in contact with a material liquid (M) in which a powder material is suspended in a liquid photocurable resin. a light irradiation device (3) for curing the photocurable resin and forming a shaped object by irradiating the material liquid with light through the plate; The plate includes a holder (4) that is movably provided and holds the shaped object, and the plate includes a glass plate (31), a transparent silicone rubber layer (32) provided on the surface of the glass plate, It has an amorphous fluororesin layer (33) provided on the surface of the transparent silicone rubber layer, and the amorphous fluororesin layer comes into contact with the material liquid.

According to this aspect, the dimensional accuracy of the model can be improved in the stereolithography apparatus. Since the amorphous fluororesin layer can suppress scattering of transmitted light, the material liquid can be irradiated with light with high precision. Furthermore, the amorphous fluororesin layer is difficult to adhere to the shaped object. The transparent silicone rubber layer can promote peeling between the amorphous fluororesin layer and the shaped object by elastically deforming. Thereby, the plate and the shaped object can be easily separated.

In the above embodiment, the thickness variation of the amorphous fluororesin layer may be ±5 μm or less.

According to this aspect, it is possible to reduce the difference in the intensity of light transmitted through each part of the amorphous fluororesin layer. Thereby, the dimensional accuracy of the shaped object can be improved.

In the above aspect, the amorphous fluororesin layer may have an amount of reflected and scattered light with respect to the incident light that is smaller than 0.025 in a region where the angle of the incident light is 15 degrees or more.

According to this aspect, the dimensional accuracy of the model can be improved in the stereolithography apparatus.

In the above aspect, the thickness of the glass plate may be set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more.

According to this aspect, a decrease in the energy of light transmitted through the glass plate is suppressed. Thereby, the thickness of each layer of the shaped object can be increased. As a result, the molding speed of the shaped object can be increased.

In the above aspect, the thickness of the transparent silicone rubber layer may be set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more, and the Shore hardness is 70 or more.

According to this aspect, a decrease in the energy of light transmitted through the transparent silicone rubber layer is suppressed. Thereby, the thickness of each layer of the shaped object can be increased. As a result, the molding speed of the shaped object can be increased.

In the above aspect, the plate is arranged to be inclined with respect to a horizontal plane, a material liquid supply part (5) for supplying the material liquid is provided on the upper end side of the plate, and a material liquid supply part (5) for supplying the material liquid is provided on the lower end side of the plate, A material liquid discharge part (6) for discharging the material liquid may be provided, and the material liquid may flow along the surface of the plate.

According to this aspect, the liquid photocurable resin can be supplied to the inner surface of the plate using gravity.

According to the above configuration, in the stereolithography apparatus, it is possible to easily separate the plate and the modeled object, and to improve the dimensional accuracy of the modeled object.

Explanatory diagram of stereolithography device Explanatory diagram of material tank Illustration of the plate An explanatory diagram that also shows the deformation of the plate when the object moves away from the plate. Graph showing the amount of reflected and scattered light against the angle of incident light for various materials An image of a model formed using a plate having an amorphous fluororesin layer and an image of a model formed using a plate having a crystalline fluororesin layer

Hereinafter, a stereolithography apparatus 1 according to an embodiment will be described with reference to the drawings. As shown in FIG. 1, the stereolithography apparatus 1 is capable of three-dimensional modeling by irradiating a material liquid M in which a powder material is suspended in a liquid photocurable resin with light to harden the photocurable resin. This is a device for forming object F. The stereolithography device 1 is a so-called 3D printer.

The stereolithography apparatus 1 includes a plate 2 , a light irradiation device 3 , a holder 4 , a material liquid supply section 5 , a material liquid discharge section 6 , a tank 7 , and a control device 8 . In this embodiment, the plate 2 constitutes at least a portion of the bottom 10A of the material tank 10.

The powder material contained in the material liquid M is a powder of a metal material that constitutes the final product. The powder material may be, for example, powder of YAG (yttrium aluminum garnet), stainless steel, or the like. The photocurable resin contained in the material liquid M is preferably a known epoxy resin or acrylic resin. Further, the photocurable resin includes a photopolymerization initiator that generates active species such as radicals or cations upon receiving light. The photocurable resin is liquid. The material liquid M, in which a powder material is suspended in a liquid photocurable resin, is in the form of a paste. The weight ratio of the photocurable resin to the powder material is preferably 1 or more and 3 or less, preferably 1 or more and 2 or less.

Moreover, the material liquid M may contain acrylic beads as a diffusion material that diffuses light. The acrylic beads preferably have a particle size of 0.5 μm or more and 10 μm or less, preferably 1 μm or more and 5 μm or less. The weight concentration of the acrylic beads in the material liquid M is preferably 1% or more and 20% or less, preferably 2% or more and 10% or less.

As shown in FIGS. 1 and 2, the material tank 10 is a substantially rectangular container with a relatively shallow depth (for example, about 5 mm) and an open top. The plate 2 is preferably provided at the center of the bottom 10A of the material tank 10. The material tank 10 extends laterally and has a first end 10B and a second end 10C. The material liquid supply section 5 is provided at the first end 10B of the material tank 10 and supplies the material liquid M to the material tank 10. The material liquid discharge part 6 is provided at the second end 10C of the material tank 10 and discharges the material liquid M in the material tank 10.

The material tank 10 is supported by a base via a support device 14. The support device 14 can change the angle of the material tank 10 with respect to the horizontal plane. The support device 14 tilts the material tank 10 downward from the first end 10B to the second end 10C. Thereby, the plate 2 is arranged obliquely with respect to the horizontal plane. Further, a material liquid supply section 5 is provided on the upper end side of the plate 2, and a material liquid discharge section 6 is provided on the lower end side of the plate 2. Thereby, the material liquid M flows along the surface of the plate 2 from the first end 10B to the second end 10C in the material tank 10 by gravity.

The material liquid supply section 5 is arranged above the first end 10B of the material tank 10. The material liquid supply section 5 is a passage member through which the material liquid M flows. The material liquid supply unit 5 is connected via a material supply pipe 17 to a tank 7 in which a material liquid M is stored. A supply pump 18 is provided in the material supply pipe 17 . By driving the supply pump 18, the material liquid M flows from the tank 7 to the first end 10B of the material tank 10 via the material supply pipe 17 and the material liquid supply section 5. A first inclined portion 10D inclined toward the material liquid supply section 5 side is formed in the bottom portion 10A of the first end portion 10B of the material tank 10.

The material liquid supply section 5 is provided with a flow rate adjustment section 19 for adjusting the flow rate of the material liquid M. The flow rate adjustment unit 19 is a regulation plate that regulates the flow of the material liquid M. The flow rate adjustment section forms a flow path with a predetermined gap d between it and the surface of the bottom 10A of the material tank 10. The gap d between the flow rate adjustment part and the surface of the bottom part 10A is set at a position corresponding to the amount required to form the object F of one layer (for example, thickness of 0.01 mm to 0.5 mm). Good.

The material liquid discharge part 6 is arranged above the second end 10C of the material tank 10. The material liquid discharge part 6 is a passage member through which the material liquid M flows. The material liquid supply section 5 is connected to the tank 7 via a material discharge pipe 21. A discharge pump 22 is provided in the material discharge pipe 21 . A second inclined portion 10E inclined toward the material liquid discharge portion 6 side is formed on the bottom portion 10A of the second end portion 10C of the material tank 10. By driving the discharge pump 22, the material liquid M flows from the second end 10C of the material tank 10 to the tank 7 via the material liquid discharge part 6 and the material discharge pipe 21.

A heater 24 and a vibration applying device 25 are provided below the bottom 10A of the material tank 10. The heater 24 maintains the material liquid M in the material tank 10 at a predetermined temperature such as 60° C. to 80° C., for example. The vibration applying device 25 may be, for example, an ultrasonic vibrator, and vibrates the material liquid M in the material tank 10.

The light irradiation device 3 includes a laser light source 3A and a scanner 3B. The laser light source 3A outputs laser light of a predetermined wavelength that hardens the photocurable resin in the material liquid M. The laser light may have a wavelength of ultraviolet light, for example. The scanner 3B irradiates the material liquid M through the plate 2 with laser light from the laser light source 3A. The scanner 3B preferably operates the laser beam along a plane parallel to the plate 2.

The holder 4 is provided above the plate 2 in the material tank 10. The holder 4 has a support surface 4A that faces the plate 2 with a gap therebetween. The support surface 4A is formed in a plane parallel to the surface of the plate 2. The holder 4 is supported by a lifting device 27 and moves up and down with respect to the plate 2. The lower part of the holder 4 and the support surface 4A protrude into the material liquid M flowing on the plate 2. That is, the lower part of the holder 4 and the support surface 4A are immersed in the material liquid M and are in contact with the material liquid M.

When the laser beam irradiated from the scanner 3B scans the material liquid M through the plate 2, the photocurable resin irradiated with the laser beam is cured, and a shaped object F is formed. The holder 4 holds the shaped object F. When the lifting device 27 moves the holder 4 upward, the shaped object F is formed in a layered manner.

As shown in FIG. 3, the plate 2 includes a glass plate 31, a transparent silicone rubber layer 32 provided on the surface of the glass plate 31, and an amorphous fluororesin layer 33 provided on the surface of the transparent silicone rubber layer 32. and has. The amorphous fluororesin layer 33 comes into contact with the material liquid M. Plate 2 has translucency.

The thickness of the glass plate 31 is preferably set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more. The glass plate 31 is preferably made of a known glass such as quartz glass, borosilicate glass, or soda lime glass. The glass plate 31 is preferably formed into a flat plate shape.

The transparent silicone rubber layer 32 is provided on the surface of the glass plate 31 facing upward, that is, the surface facing inside the material tank 10. The thickness of the transparent silicone rubber layer 32 is set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more, and the Shore hardness is 70 or more. The transparent silicone rubber layer 32 is preferably formed by applying liquid transparent silicone rubber to the surface of the glass plate 31 and solidifying it.

The amorphous fluororesin layer 33 is provided on the surface of the transparent silicone rubber layer 32 facing upward, that is, the surface facing inside the material tank 10. The amorphous fluororesin layer 33 is formed of a known amorphous fluororesin, such as CYTOP-100 (registered trademark, AGC Corporation) or Teflon ^TM AF (registered trademark, Mitsui Chemours Fluoro Products Co., Ltd.). It's good to have one. The amorphous fluororesin layer 33 preferably has an amount of reflected and scattered light of less than 0.025 in a region where the incident angle is 15 degrees or more. The amount of reflected and scattered light is expressed as a ratio to the amount of incident light. Preferably, the variation in thickness of the amorphous fluororesin layer 33 is ±5 μm or less. The thickness of the amorphous fluororesin layer 33 is set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more. The amorphous fluororesin layer 33 is preferably formed by applying a liquid amorphous fluororesin to the surface of the clear silicone rubber layer and solidifying it.

As shown in FIG. 1, the control device 8 is a computer that controls the stereolithography device 1. Control device 8 includes a microprocessor, nonvolatile memory, volatile memory, and an interface. The control device 8 controls the light irradiation device 3 (laser light source 3A, scanner 3B), heater 24, vibration applying device 25, lifting device 27, and supply pump 18 by reading and executing a program stored in a non-volatile memory. , controls the discharge pump 22.

The operation of the stereolithography apparatus 1 will be described with reference to FIG. 2. Initially, the support device 14 maintains the material tank 10 at a desired inclination angle θ. Thereby, the material tank 10 is inclined downward from the first end 10B to the second end 10C. Next, the control device 8 drives the supply pump 18 and the discharge pump 22. As a result, the material liquid M in the tank 7 flows to the material liquid supply section 5 via the material supply pipe 17.

The material liquid M supplied to the material liquid supply section 5 is supplied to the first end 10B of the material tank 10. Since the material tank 10 is inclined at the inclination angle θ, the material liquid M supplied to the material tank 10 flows toward the second end portion 10C due to gravity. The gap d between the lower end of the flow rate adjustment section 19 and the bottom 10A is set to a depth necessary for forming the object F of at least one layer. Therefore, the material liquid M having a thickness corresponding to the gap d flows from the flow rate adjustment section 19 onto the upper surface of the plate 2. The material liquid M that has passed over the upper surface of the plate 2 flows to the material liquid discharge part 6 via the second inclined part 10E. The material liquid M that has reached the material liquid discharge section 6 flows into the tank 7 via the material discharge pipe 21 by the suction action of the discharge pump 22 .

The control device 8 maintains the material liquid M flowing in the material tank 10 at a predetermined temperature by driving the heater 24 . Further, the control device 8 may apply vibration to the material liquid M flowing in the material tank 10 by driving the vibration applying device 25. These suppress the retention of the material liquid M and the precipitation of the powder material in the material liquid M, and the flow of the material liquid M can be appropriately controlled.

While the material liquid M is being supplied to the material tank 10, the control device 8 drives the lifting device 27 to move the holder 4 up and down with respect to the material liquid M flowing on the upper surface of the plate 2. In this case, the lifting device 27 moves the holder 4 so that the distance between the support surface 4A of the holder 4 and the top surface of the plate 2 is one layer of the object F, for example, about 0.01 mm to 0.5 mm. . Further, the control device 8 drives the light irradiation device 3, and the scanner 3B of the light irradiation device 3 irradiates the material liquid M through the plate 2 with laser light. As a result, the photocurable resin in the material liquid M irradiated with the laser light is cured, and a shaped object F is formed. The shaped object F includes a cured photocurable resin and a powder material mixed into the photocurable resin.

The first layer of shaped objects F is formed on the support surface 4A of the holder 4 and is bonded to the support surface 4A. That is, the shaped object F is supported by the holder 4. When one layer of the modeled object F is formed, the holder 4 is lifted upward by the lifting device 27. Thereby, the shaped object F formed between the holder 4 and the plate 2 is pulled upward while being held by the holder 4 and is separated from the plate 2. At this time, the shaped object F is peeled off from the plate 2.

When the plate 2 is inclined with respect to the moving direction of the holder 4, the shaped object F can be peeled off from the plate 2 with a smaller load than when the plate 2 is perpendicular to the moving direction of the holder 4. . Furthermore, since the amorphous fluororesin layer 33 provided on the outermost surface of the plate 2 has low adhesion to the object F, the object F can be easily peeled off from the plate 2. The amorphous fluororesin layer 33 has lower adhesion to the object F than the glass plate 31 and the transparent silicone rubber layer 32. Moreover, the transparent silicone rubber layer 32 facilitates peeling of the shaped object F from the plate 2 by deforming. As shown in FIG. 4, when the holder 4 rises with the object F adhered to the amorphous fluororesin layer 33, the transparent silicone rubber layer 32 and the amorphous fluororesin layer 33 are pulled by the object F. Deforms elastically. At this time, a restoring force acts on the transparent silicone rubber layer 32 and it tries to separate from the object F. The amount of elastic deformation of the transparent silicone rubber layer 32 is greatest at a portion corresponding to the edge of the bonded portion between the shaped object F and the amorphous fluororesin layer 33. Therefore, the restoring force of the transparent silicone rubber layer 32 is greatest in the portion corresponding to the edge of the bonded portion between the shaped object F and the amorphous fluororesin layer 33. As a result, a force for peeling off the amorphous fluororesin layer 33 from the article F acts on a portion corresponding to the edge of the adhesive portion between the article F and the amorphous fluororesin layer 33, and Peeling of the amorphous fluororesin layer 33 is promoted.

As the holder 4 rises, the liquid material M is supplied by gravity to the gap between the lower surface of the object F supported by the holder 4 and the upper surface of the plate 2. The gap between the lower surface of the object F and the upper surface of the plate 2 is set to one layer of the object F, for example, approximately 0.01 mm to 0.5 mm. In this state, the scanner 3B of the light irradiation device 3 irradiates the laser beam again, so that a new layer of the object F is formed on the lower surface of the object F. In this way, by repeating the laser beam irradiation by the light irradiation device 3 and the raising of the holder 4, a layered object F is formed, and a three-dimensional object F is formed.

After the formation of the modeled object F by photocuring of the photocurable resin is completed, the holder 4 is raised and the modeled object F is pulled up from the material liquid M. Thereafter, the shaped object F is separated from the holder 4. The resin of the obtained shaped object F is removed by a degreasing process. Finally, by sintering the shaped article F from which the resin has been removed, a metal product of a desired shape made of a metal material as a powder material is obtained.

The effects of the stereolithography apparatus 1 according to the embodiment will be explained. Since the outermost layer of the plate 2 is formed of an amorphous fluororesin, the dimensional accuracy of the shaped object F can be improved. The amorphous fluororesin layer 33 can suppress scattering of transmitted light more than the crystalline fluororesin. Thereby, the material liquid M can be irradiated with light with high precision. FIG. 5 shows the intensity of the amount of reflected and scattered light with respect to the angle of incident light for various materials. The intensity of the amount of reflected and scattered light represents the ratio of the amount of reflected and scattered light to the amount of incident light. In FIG. 5, the materials used are CYTOP-100 (AGC Co., Ltd., Example 1), AF-90 (Mitsui Chemours Fluoro Products Co., Ltd., Example 2), and PTFE (Comparative Example 1). The material in Examples 1 and 2 is an amorphous fluororesin, and the material in Comparative Examples 1 and 2 is a crystalline fluororesin. It can be seen from FIG. 5 that the reflected and scattered intensities of Examples 1 and 2, which are amorphous fluororesins, are smaller than those of Comparative Examples 1 and 2, which are crystalline fluororesins. In Examples 1 and 2, the amount of reflected and scattered light relative to the incident light is smaller than 0.025 in a region where the angle of the incident light is 15 degrees or more.

FIG. 6 shows a modeled object F when the amorphous fluororesin according to Examples 1 and 2 is applied to the amorphous fluororesin layer 33 of the stereolithography apparatus 1 according to the embodiment. This is an image showing the shape. FIG. 6 shows, as a comparative example, a modeled object F when the crystalline fluororesin according to comparative example 1 is applied to the amorphous fluororesin layer 33 of the stereolithography apparatus 1 according to the embodiment. This is an image showing the shape of . The shaped objects F according to A, B, and C of FIG. 6 were formed under the following conditions. The powder material was YAG with a particle size of 33 μm, the photocurable resin was 1487F (Okamoto Chemical Industry Co., Ltd.), the mixing ratio of the powder material and the photocurable resin was 1:1.5, and the light irradiation device The output of the laser beam irradiated from No. 3 was set to 225 mW. The shape of the target object F is approximately the same as the shape shown in FIGS. 6A and 6B. As shown in FIG. 6C, when Comparative Example 1, which is a crystalline fluororesin, is used, an excessive hardened portion is formed around the target object F. That is, when Comparative Example 1, which is a crystalline fluororesin, was used, it was confirmed that the molding accuracy of the shaped object F was reduced. The reason for this is thought to be the difference in the amount of reflected and scattered light between the materials, as shown in FIG. Since the amorphous fluororesin does not include a crystal structure like the crystalline fluororesin, scattering of light is suppressed and the irradiation range of the laser beam can be kept narrow.

The transparent silicone rubber layer 32 can promote peeling between the amorphous fluororesin layer 33 and the shaped object F by elastically deforming.

Since the variation in the thickness of the amorphous fluororesin layer 33 is ±5 μm or less, the difference in intensity of light transmitted through each part of the amorphous fluororesin layer 33 can be reduced. Thereby, the dimensional accuracy of the shaped object F can be improved.

The amorphous fluororesin layer 33 preferably has an amount of reflected and scattered light of less than 0.025 in a region where the incident angle is 15 degrees or more. By suppressing the scattering of laser light, the dimensional accuracy of the shaped object F can be improved.

The glass plate 31 preferably has a light transmittance of 99% or more. Further, the transparent silicone rubber layer 32 preferably has a light transmittance of 99% or more. This suppresses a decrease in the energy of light that passes through the glass plate 31 and the transparent silicone rubber layer 32. Thereby, the thickness of the shaped object F per layer can be increased. As a result, the molding speed of the shaped object F can be increased.

The acrylic beads contained in the material liquid M scatter the laser light within the material liquid M and promote curing of the photocurable resin. That is, the material liquid M containing acrylic beads is cured more by the same intensity of laser light than the material liquid M not containing acrylic beads. Thereby, for the same intensity of laser light, the material liquid M containing acrylic beads can have a thicker moldable thickness per layer than the material liquid M not containing acrylic beads.

Although the description of the specific embodiments has been completed above, the present invention is not limited to the above-mentioned embodiments and can be widely modified and implemented.

1 : Stereolithography device 2 : Plate 3 : Light irradiation device 4 : Holder 4A : Support surface 5 : Material liquid supply part 6 : Material liquid discharge part 10 : Material tank 10A : Bottom part 10B : First end part 10C : Second end Section 27: Lifting device 31: Glass plate 32: Transparent silicone rubber layer 33: Amorphous fluororesin layer F: Modeled object M: Material liquid

Claims (6)

A stereolithography device,
a translucent plate having a surface in contact with a material liquid in which a powder material is suspended in a liquid photocurable resin;
a light irradiation device that cures the photocurable resin by irradiating the material liquid with light through the plate to form a shaped object;
a holder that is movably provided with respect to the plate and holds the shaped object;
The plate includes a glass plate, a transparent silicone rubber layer provided on the surface of the glass plate, and an amorphous fluororesin layer provided on the surface of the transparent silicone rubber layer,
A stereolithography device in which the amorphous fluororesin layer contacts the material liquid. The stereolithography apparatus according to claim 1, wherein the variation in thickness of the amorphous fluororesin layer is ±5 μm or less. 3. The stereolithography apparatus according to claim 1, wherein the amorphous fluororesin layer has an amount of reflected and scattered light with respect to the incident light that is smaller than 0.025 in a region where the angle of the incident light is 15 degrees or more. The stereolithography apparatus according to any one of claims 1 to 3, wherein the thickness of the glass plate is set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more. The transparent silicone rubber layer according to any one of claims 1 to 4, wherein the thickness is set so that the transmittance for light of 300 nm or more and 400 nm or less is 99% or more, and the Shore hardness is 70 or more. The stereolithography device described in Section 1. the plate is arranged obliquely with respect to a horizontal plane;
A material liquid supply section for supplying the material liquid is provided on the upper end side of the plate,
A material liquid discharge part for discharging the material liquid is provided on the lower end side of the plate,
The stereolithography apparatus according to any one of claims 1 to 5, wherein the material liquid flows along the surface of the plate.

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