KR101809194B1

KR101809194B1 - A 3-Dimensional Object Forming Apparatus and Forming Method Thereof

Info

Publication number: KR101809194B1
Application number: KR1020150169395A
Authority: KR
Inventors: 이병극; 이광민; 연은숙; 최영한; 정창호; 이희강
Original assignee: 주식회사 캐리마
Priority date: 2015-11-30
Filing date: 2015-11-30
Publication date: 2017-12-14
Also published as: WO2017095125A1; KR20170063247A

Abstract

The present invention relates to a three-dimensional molding apparatus and a control method thereof. A 3D forming apparatus for forming a three-dimensional object by an exposure curing system, comprising: a resin tank for containing a photocurable liquid resin; A molding plate on which the three-dimensional object is molded; A shaping plate driving unit for lifting the shaping plate; An image light irradiating unit for irradiating image light corresponding to a unit image toward the shaping plate; And the unit image is divided into a plurality of exposure areas including a boundary area and at least one inner area, and each of the exposure areas is irradiated with image light under different light irradiation conditions, And the control unit controls the image light irradiation unit to be cured earlier than the region to be cured. Such a three-dimensional molding apparatus according to the present invention minimizes the deformation caused by the shrinkage of the photo-curing resin, and can form a product with high dimensional precision.

Description

[0001] The present invention relates to a three-dimensional object forming apparatus and a forming method thereof,

The present invention relates to a three-dimensional object molding apparatus and a molding method thereof.

In a conventional plane exposure type three-dimensional object molding apparatus, that is, a 3D printer, unit molding layers are sequentially laminated on a molding plate to mold a desired 3D object. Each unit molding layer is formed by curing the liquid resin exposed to the image light provided in the light irradiation apparatus.

However, in such a surface exposure type 3D forming apparatus, shrinkage inevitably occurs along the surface direction of the layer in the process of curing the unit forming layer, and the shrinkage becomes larger as the area of one layer is wider. When the cylinder is filled with an empty space and the inside is filled and the cross-sectional area is rapidly increased, the dimensional accuracy is lowered due to deformation due to shrinkage or overcorrection. Such deformation due to shrinkage and curing is an important cause of degrading the shape precision of the final product.

SUMMARY OF THE INVENTION An object of the present invention is to provide a three-dimensional object molding apparatus and a molding method thereof that reduce the shrinkage of a resin to increase the shape accuracy.

According to an aspect of the present invention, there is provided a 3D forming apparatus for forming a three-dimensional object by an exposure curing system, comprising: a resin tank for containing a photocurable liquid resin; A molding plate on which the three-dimensional object is molded; A shaping plate driving unit for lifting the shaping plate; An image light irradiating unit for irradiating image light corresponding to a unit image toward the shaping plate; And the unit image is divided into a plurality of exposure areas including a boundary area and at least one inner area, and each of the exposure areas is irradiated with image light under different light irradiation conditions, And the control unit controls the image light irradiation unit to be cured earlier than the region to be cured.

According to a preferred embodiment, the exposure start of the exposure regions is sequentially performed from the boundary region to the internal region with a time difference. As a result, the boundary region is cured first and then the inner region is hardened, so that the contraction of the final formed three-dimensional object is minimized and the shape accuracy can be maintained.

The early setting of the boundary region may be achieved by controlling at least one of the exposure duration, light wavelength, light intensity and exposure pattern for the exposure regions to be different.

According to a preferred embodiment of the present invention, there is a non-exposed buffer region corresponding to a certain pixel value between the boundary region and the at least one inner region.

According to another aspect of the present invention, there is provided a 3D forming method for forming a three-dimensional object by an exposure hardening method, the method comprising: dividing a unit image into a plurality of exposure regions each consisting of a boundary region and at least one inner region step; Applying different light irradiation conditions to each of the exposure regions; And exposing the boundary region and the at least one interior region to the different light exposure conditions so that the boundary region is cured earlier than the at least one interior region. .

According to another aspect of the present invention, there is provided a 3D molding apparatus for molding a three-dimensional object by an exposure curing system, comprising: a resin tank for containing a photocurable liquid resin; A molding plate on which the three-dimensional object is molded; A shaping plate driving unit for lifting the shaping plate; An image light irradiating unit for irradiating image light corresponding to a unit image toward the shaping plate; And the unit image is divided into a plurality of exposure areas including a boundary area and at least one inner area, and each of the exposure areas is irradiated with image light under different light irradiation conditions, And the control unit controls the image light irradiating unit so as to be cured at a higher hardness than that of the area.

According to a preferred embodiment, the exposure regions are different from each other in at least one of an exposure start time, an exposure duration, an optical wavelength, a light intensity, and an exposure pattern.

According to a preferred embodiment, the photo-curable liquid resin contains a plurality of resin materials having different hardening wavelengths and different hardening intensities. The boundary region is irradiated with image light in a wavelength range suitable for a resin material having a relatively high curing strength, And an image light in a light wavelength range suitable for a resin material having a relatively low curing strength is irradiated to the inner region.

According to the three-dimensional object molding apparatus and method of the present invention, since the boundary region is hardened earlier or hardened to a higher hardness than the inner region, the deformation of the formed shape can be minimized and a high quality product with high dimensional accuracy can be molded.

1 is a conceptual diagram of a three-dimensional object molding apparatus according to the present invention.
2 is a flow chart of a control unit of a three-dimensional object molding apparatus according to the present invention.
3 is an XY cross-sectional view of a three-dimensional object according to the present invention divided into a boundary region and an inner region.
4 is an XY cross-sectional view of a three-dimensional object according to the present invention divided into a boundary region and a plurality of inner regions.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The features and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

1 is a conceptual diagram of a three-dimensional object molding apparatus according to the present invention. The liquid photocurable polymer resin (1) is stored in the resin tank (30). A three-dimensional object (2) is attached to the molding plate (20). The three-dimensional object 2 is formed such that thin unit-shaped molded layers are sequentially laminated along the Z-axis direction to have a three-dimensional shape. The bottom of the resin trough 30 is transparent and allows the image light generated by the image light irradiation unit 4 to pass therethrough. The present invention is not limited to the 3D printing apparatus of the resin trench type. The image light irradiated by the image light irradiating unit 40 exposes a liquid photocurable polymer at the lowermost part of the object 2, whereby the liquid photocurable polymer is cured to a solid state, Respectively. The liquid photocurable resin contained in the resin trough 30 replenishes the lower portion of the object and the next layer is formed by the image light irradiated from the image light irradiating portion 40. These steps are repeated to form a three-dimensional object having a final target shape. The three-dimensional molding apparatus according to the present invention can be applied not only to a method of interposing a molding plate by intermittently raising the molding plate as described above, but also by sequentially changing the image light corresponding to a unit image while continuously raising the molding plate A continuous molding method can be adopted. The present invention can be used not only in the resin trench method but also in the 3D printer of the resin coating method.

2 is a flow chart of a control unit of a three-dimensional object molding apparatus according to the present invention. The control unit obtains a unit image of the unit forming layers or a unit image of each cross section for continuous forming (S220). The obtained unit images are divided into a plurality of exposure regions each consisting of a boundary region and at least one inner region (S230). When partitioning, one unit image can be divided into two exposure regions, a boundary region and an inner region, as shown in Fig. Alternatively, as shown in FIG. 4, a boundary region can be divided into two boundary regions. Different light irradiation conditions are applied to the respective exposure regions in one unit image (S240). A signal relating to the region image light corresponding to each exposure region to which the light irradiation condition is given is provided to the image light irradiation portion 40 and the image light irradiation portion 40 applies the image light to the transparent bottom plate of the resin tank 30 And exposes the resin layer interposed between the shaping plate 20 and the bottom plate (S250).

3 is divided into one boundary area A1 and one inner area A2.

FIG. 4 shows one boundary area B1 and two sequential inner areas B2 and B3.

When the boundary area A1 is cured first and the inner area A2 is cured sequentially, the boundary area between the boundary area and the inner area is exposed to an area corresponding to one pixel, two pixels or even tens of pixels in some cases It is possible to set a buffer area which is not performed. If too much hardening occurs in the inner area after the boundary area is hardened, the inner area may invade the boundary area and damage the dimensional stability of the boundary area. The resin in the buffer region is affected by the light of the adjacent pixels and some of the resin is cured. However, it does not occur until the invasion of the bounding region caused by the curing. By setting the buffer region which does not expose the pixel of the predetermined amount between the boundary region and the inner region, the boundary region and the inner region can coexist harmoniously.

The difference in light irradiation conditions between the boundary region and the at least one inner region is to allow the boundary region to cure earlier and / or at a higher intensity than the inner region. As a result, the boundary region of the outer boundary is first cured or has a higher strength, so that shrinkage along the sheet surface direction of the unit forming layer, which may occur while the inner region is cured, can be minimized. The thickness of the boundary region, that is, the width in the planar direction, is appropriately selected to be large enough to effectively prevent shrinkage considering the cross-sectional size of the formed product. It is possible to form a shape in which a cylinder-shaped object whose interior is an empty space is transformed into a cylindrical object having a hollow interior. In this case, using the conventional technique, the boundary dimension can be larger or smaller due to the difference in the exposed areas of the previous shaping layer and the current shaping layer in the portion deformed from the cylindrical shape to the cylindrical shape on the image data . The present invention minimizes the deformation by exposing the boundary area first or by forming it more strongly to fill the inside area when the object of such shape is formed.

The thickness of the boundary region in general molding conditions is preferably 2 to 5 mm, and the thickness of the boundary region is preferably the same or approximate to that of the previous formed layer.

The difference in the light irradiation conditions can be given by making the condition of any one of the exposure start time, the exposure duration, the light wavelength, the light intensity and the exposure pattern or the plurality of conditions different.

In the temporal difference exposure method in which a time difference is set at the start of exposure, the boundary region A1 is first exposed and then the boundary region A1 is first cured. When the inner area A2 is exposed after the exposure of the boundary area A1 or during the exposure, the boundary area A1 is already cured to a considerable extent during the hardening of the inner area A2, Even if shrinkage occurs during curing, the influence of shrinkage of the inner region A2 does not affect the boundary dimension A1, that is, the outer dimension of the three-dimensional object. In the case of FIG. 4, the boundary region B1 and the two inner regions B2 and B3 are exposed by sequentially shifting the time from the outside to the inside. Accordingly, the region B1 is first cured, and the regions B2 and B3 are sequentially cured, thereby minimizing shrinkage due to curing as a whole. At this time, since the regions B1, B2, and B3 are spaced apart from each other by a certain distance, the effect of minimizing the distortion or stress of the external regions B2 and B1 due to shrinkage and deformation occurring during curing of the internal regions B3 and B2 I have.

The boundary region may be cured earlier than the inner region by differentiating the light intensity, the light wavelength, and the light irradiation time in another method of changing the light irradiation conditions for the boundary region and the at least one inner region. That is, when the image light is irradiated so that the light intensity applied to the boundary region is higher than the light intensity applied to the inner region, the boundary region hardens earlier or has a higher hardness than the inner region. This effect can be achieved substantially the same by differentiating the illumination duration, i. E. By irradiating the boundary region with a longer time image light compared to the interior region.

Alternatively, the boundary region and the inner region may be irradiated with image light having a different wavelength, so that the boundary region may be hardened or hardened earlier than the inner region. The liquid resin takes into account the characteristics of the curing characteristics varying depending on the light wavelength of the exposed image light. In this case, it is preferable to use a composite liquid resin in which a plurality of resin materials having different light wavelengths to be cured are mixed. These resin materials are combined with different properties such as strength, hardness, elasticity and impact resistance in a cured state. For example, a hybrid liquid resin in which an acryl-based resin and an epoxy-based resin are mixed is used as a molding resin. Polymerization initiator suitable for acryl-based resin and polymerization initiator suitable for epoxy-based resin Mixed in a hybrid form. Acrylic resins react to cure at the light wavelength corresponding to visible light or ultraviolet light. On the other hand, epoxy resins react only with ultraviolet rays. Epoxy-based resins have higher hardness and strength than acrylic-based resins. Therefore, when light having a wavelength corresponding to the ultraviolet ray is irradiated to the boundary region and light having a wavelength corresponding to the visible light is irradiated to the internal region, the epoxy resin and the acrylic resin are cured by the hybrid in the boundary region, Cure the resin to the main. Therefore, the boundary region has a strong hardness and the inner region has a relatively low hardness as compared with the boundary. The mixing ratio of the acrylic resin and the epoxy-based resin can be appropriately selected in accordance with the area ratio of the boundary region and the inner region. The type of the resin material constituting such a hybrid liquid resin can be appropriately selected from commercially available liquid resin for 3D printers. The combination of the resin materials can be selected so as to obtain a combination of physical properties such as strength / elasticity, hardness / impact resistance, and high cost / low cost with respect to the boundary / interior.

The light irradiation condition differentiation between the boundary region and the inner region can be also obtained by differentiating the exposure pattern. The exposure pattern refers to a planar shape that can be obtained by uniformly exposing each section to the entire surface of the plate and partially providing a non-exposed portion. As the number of unexposed portions increases or becomes larger, the overall planar texture density of the region becomes lower. The control unit divides the cross-sectional image into the boundary and the inner region, gives the exposure pattern with a relatively high density of the boundary region, and gives the exposure pattern with a lower density of the boundary region than the boundary region. The differentiation of the exposure pattern can be applied alone or in combination with the differentiation of the different exposure conditions described above. For example, referring to FIG. 4, the boundary region B1 has a relatively high light intensity to solid-expose the entire region, and the first inner region, i.e., the inner boundary region B2, (B1). Whereby the boundary region is cured first or hardened to a higher hardness than the first inner region. Then, the inner inner area B3 was exposed with a lattice-like exposure pattern surrounding a plurality of non-exposed portions distributed in the form of a matrix. As a result, the boundary region B1 has the strongest light intensity and is solidly exposed, so that the curing is first performed. Since the light intensity of the B2 region is less than that of the boundary region, more curing time is required or the hardness is lowered. Since the B3 region exposed with the lattice-shaped exposure pattern has many unexposed portions, the texture density and hardness in the planar direction are significantly lower than that in the outer-region inner region B2. Therefore, the contraction force in the planar direction is insignificant in the curing process, so that the shrinkage stress applied to the outer peripheral region B2 and the boundary region B1 becomes extremely low. The exposure pattern of the internal area B3 can be appropriately selected according to the size of the unexposed area, the size of the lattice, the line width of the lattice, etc., according to the cross-sectional area of each cross section, the intensity required for the three-dimensional object, In any case, the exposure pattern of the exposure regions is designed so that the non-exposed portion increases from the outer portion to the inner portion, thereby gradually decreasing the texture density, thereby minimizing the shrinking stress applied to the boundary region. This differentiation of the exposure pattern also helps to improve the economical efficiency by saving the resin material.

As described above, by differentiating the light irradiation conditions of the boundary region and the inner region, the boundary region of the cross section exposed in each unit image light is hardened earlier or harder than the inner region, The contraction stress in the direction can be minimized and the shape accuracy can be increased. As described above, the light irradiation conditions capable of differentiating the regions are the exposure start time, the exposure duration, the light intensity, the optical wavelength, the exposure pattern, and the like, and these can be applied alone or in combination.

The user interface 60 of Fig. 1 is provided with an operation button 62 and a printing button 64 of the three-dimensional object molding apparatus. The user or the operator sets the three-dimensional forming apparatus of the present invention in various modes by pressing the operation button. Precision molding may be required depending on the shape of the object to be molded. An object having the same shape as a cylindrical shape having an empty space inside and a cylindrical object filled with an inner space is combined. When the thickness of the cylinder shape is set to the boundary thickness and the molding is carried out, the accuracy of the dimension can be achieved since the boundary is hardened first and then the inside is hardened during the molding of the columnar body. At this time, the operation button is pressed to enter the precision forming mode, and the forming of the object is started after the work of setting the boundary thickness. Release the precision molding mode after molding is finished. However, the present invention is not limited to such operation buttons.

1: Resin
2: object
10: Body of three-dimensional object molding apparatus
20: Molded plate
30:
40: image light irradiation unit
50:
60: User interface
62: Operation button
64: Printing button
70:

Claims

In a 3D forming apparatus for forming a three-dimensional object by an exposure hardening method,
A resin tank for containing the photocurable liquid resin;
A molding plate on which the three-dimensional object is molded;
A shaping plate driving unit for lifting the shaping plate;
An image light irradiating unit for irradiating image light corresponding to a unit image corresponding to a unit molding layer of the three-dimensional object toward the shaping plate;
An operation button for setting a precision forming mode or releasing the set precision forming mode; And
When the precision molding mode is set by operation of the operation button, the unit image corresponding to the unit molding layer is divided into a plurality of exposure regions each composed of a boundary region and at least one inner region, Irradiating the exposure regions with image light under different light irradiation conditions to control the image light irradiating portion so that the boundary region is cured earlier than the at least one inner region, And a control section for forming a plurality
And the width of the boundary region in the direction of the surface of the boundary is selected to be a size that can effectively prevent shrinkage.

The method according to claim 1,
So that the exposure start of the exposure regions is sequentially performed from the boundary region to the internal region with a time difference.

3. The method according to claim 1 or 2,
Wherein the boundary region is exposed with a solid exposure pattern and the at least one inner region is exposed with a lattice-shaped exposure pattern.

3. The method according to claim 1 or 2,
Wherein a non-exposed buffer region corresponding to a certain pixel value exists between the boundary region and the at least one inner region.

A 3D forming method for forming a three-dimensional object by an exposure hardening method,
Setting a precision molding mode by operating an operation button;
Dividing a unit image corresponding to a unit forming layer of the three-dimensional object into a plurality of exposure regions each consisting of a boundary region and at least one inner region, when the precision molding mode is set;
Applying different light irradiation conditions to each of the exposure regions according to the unit forming layer; And
The unitary molding layer is exposed to the boundary region and the at least one inner region under the different light irradiation conditions so that the boundary region is cured earlier than the at least one inner region, Shaping the three-dimensional object,
Wherein the width of the boundary region in the direction of the surface of the plate is selected so as to be capable of effectively preventing shrinkage.

6. The method of claim 5,
Wherein the boundary region is exposed with a solid exposure pattern, and the at least one inner region is exposed with a lattice-shaped exposure pattern.

In a 3D forming apparatus for forming a three-dimensional object by an exposure hardening method,
A resin tank for containing the photocurable liquid resin;
A molding plate on which the three-dimensional object is molded;
A shaping plate driving unit for lifting the shaping plate;
An image light irradiating unit for irradiating image light corresponding to a unit image corresponding to a unit molding layer of the three-dimensional object toward the shaping plate;
An operation button for setting a precision forming mode or releasing the set precision forming mode; And
Wherein when the precision molding mode is set by the operation of the operation button, the unit image is divided into a plurality of exposure regions each composed of a boundary region and at least one inner region, Irradiating the image light with irradiation conditions to control the image light irradiating unit so that at least one of the hardness and the intensity of the boundary region is higher than that of the at least one inner region, And a control section for forming a plurality
And the width of the boundary region in the direction of the surface of the boundary is selected to be a size that can effectively prevent shrinkage.

8. The method of claim 7,
Wherein the boundary region is exposed with a solid exposure pattern and the at least one inner region is exposed with a lattice-shaped exposure pattern.

9. The method of claim 8,
Wherein the photocurable liquid resin contains a plurality of resin materials having different hardening wavelengths and different hardening intensities and irradiates image light in a wavelength range corresponding to ultraviolet light for curing a resin material having a relatively high hardening strength, Wherein the internal region irradiates image light in a wavelength range corresponding to a visible light for curing a resin material having a relatively low curing strength.