JPH0815760B2 - Photo-curing molding device with recoater travel adjustment mechanism - Google Patents

Description

[Technical Field] The present invention relates to an improvement of a photo-curing modeling device,
In particular, the upper surface of the cured layer is coated with uncured photocurable liquid.
This relates to a technology for shortening the time required for coating by adjusting the travel distance of a recoater to the minimum necessary when running the recoater along the liquid surface to achieve this.

BACKGROUND ART Photo-curing molding technology has been developed to actually mold a three-dimensional object having a non-existent three-dimensional shape, such as a three-dimensional shape designed using a CAD system.
In this technique, a liquid that hardens when irradiated with light is used, and this liquid is stored in a liquid tank.
In one step, light is selectively irradiated onto a specific position on the surface of the photo-curable liquid to form a cured layer corresponding to a certain cross-section. Next, in the second step, the cured layer is allowed to settle. Then, in the third step, uncured photo-curable liquid is introduced onto the top surface of the cured layer. These first to third steps constitute one cycle, and by repeating this cycle, the cured layers are stacked to form an integrated three-dimensional object. By controlling the irradiation area for each cross-section, a three-dimensional object of any shape can be formed. This technology is disclosed in Japanese Patent Laid-Open Publication No. 144478/1981 and U.S. Patent No. 2,775,758.

In this photo-curing modeling technology, if the amount of sedimentation of the cured layer per step is large, the uncured liquid will flow onto the cured layer from the surrounding area simply by settling the cured layer. Therefore, no special operation is required for the third step. However, if the amount of sedimentation per step is small, the viscosity or surface tension of the uncured liquid may prevent the uncured liquid from flowing onto the cured layer simply by settling the cured layer. Alternatively, it may take a long time for the uncured liquid to flow. Therefore, various proposals have been made to realize or accelerate the third step.

U.S. Patent 4,575,330 proposes a technique in which the hardened layer is first significantly lowered, allowing the unhardened liquid to flow onto the hardened layer, and then the hardened layer is raised, thereby reducing the thickness of the unhardened liquid. However, with this technique, the lowering and rising of the hardened layer causes ripples in the liquid surface, and it takes time for the ripples to calm down and the liquid level to stabilize.

Japanese Patent Application Laid-Open No. 61-114818 discloses a technique in which, after the hardened layer has settled, a smooth plate is run across the entire liquid tank, pushing the unhardened liquid onto the upper surface of the hardened layer with the front surface of the smooth plate. A technique in which a brush is run instead of a smooth plate is also known. The applicant has also proposed a technique for achieving the third step by running a recoater, which has a lower surface that forms a minute gap between itself and the upper surface of the hardened layer, along the liquid surface. This proposal, however, was an undisclosed invention at the time of filing this application.

The above-mentioned technique, in which a recoater such as a smooth plate or a brush is moved along the liquid surface, is widely used today because it allows the upper surface of the cured layer to be recoated with uncured liquid in a relatively short time. However, as the size of the equipment has increased in recent years, new problems have arisen.

A photo-curing modeling device is shown schematically in Figure 1, where F indicates a liquid tank. A in the figure indicates a means for storing contour data for each cross section that defines a three-dimensional shape. A light irradiation area control means E controls the light irradiation area based on this contour data, resulting in a light irradiation area I having a contour defined by the contour data. The cured layer, which is cured by light irradiation and has its contour controlled as described above, is then settled by settling means G. After settling, a recoater H travels along the liquid surface to perform the recoating process. D in the figure indicates a means for moving the recoater H.

In order to form a large three-dimensional object using such a photo-curing modeling device, it is necessary to use a large liquid vat F. However, in practice, a large liquid vat F may be used to form a small three-dimensional object. In the example shown in FIG. 1, the light irradiation area I is considerably smaller than the liquid vat F, but in reality, there are cases where the light irradiation area is extremely small. In such cases, the range that the recoater H needs to travel to actually recoat is only the range of the light irradiation area I.

However, in current photo-curing modeling devices, the recoater H travels uniformly over the entire area of the liquid tank, wasting time by traveling over areas that do not actually need to be recoated.

The present invention aims to reduce the time required for recoating by eliminating unnecessary travel of the recoater H. To this end, the present invention adds minimum/maximum coordinate calculation means B for calculating the minimum coordinate YMIN and maximum coordinate YMAX of the light irradiation area I relative to the axis Y along the travel direction of the recoater H based on the contour data stored in contour data storage means A, and travel stroke restriction means C for restricting the travel range of the recoater travel means D to be between the minimum coordinate YMIN and maximum coordinate YMAX calculated by the minimum/maximum coordinate calculation means B.

According to this invention, the travel distance, i.e., the travel range, of the recoater H is restricted to the travel distance actually required for recoating, so that no time is wasted on unnecessary travel and no insufficient recoating occurs.

In the present invention, the minimum and maximum coordinate calculation means B is
The minimum and maximum coordinates in all cross sections are calculated, i.e., as is clear from the example shown in Figure 2, the minimum coordinate YMIN and maximum coordinate YMAX of the entire three-dimensional object J to be formed are calculated, and the travel stroke limiting means C may uniformly limit the travel stroke between YMIN and YMAX in all cross sections. In this way, problems such as insufficient recoating during the formation of a three-dimensional object do not occur, and unnecessary travel can be significantly reduced. Note that Figure 2(b) shows a projection view from the vertical axis Z direction perpendicular to the Y axis.

Even more preferably, the minimum/maximum coordinate calculation means B should calculate the minimum/maximum coordinates for the cross section just irradiated and the cross section to be irradiated next. In this way, as is clear from Figure 3, the recoater travels at least for the cross section just irradiated, so no recoat residue occurs. Furthermore, the recoater travels over the cross section to be irradiated next, so there is no interference between the recoater and the next irradiation area. In this way, with this system, the travel distance of the recoater H is adjusted to the minimum necessary for each cross section. In Figure 3, YD indicates the range for the cross section just irradiated, and YU indicates the range for the cross section to be irradiated next. Finally, Y indicates the travel distance of the recoater.

In the present invention, the smaller the difference between the minimum coordinate YMIN and the maximum coordinate YMAX, that is, the shorter the recoating stroke, as is clear from a comparison of Figures 4(A) and 4(B), the more preferably the running speed of the recoater H is increased. If the running stroke is short, no recoat residue will remain even when the recoater runs at high speed, and the recoating time can be further reduced.

Furthermore, in the present invention, the minimum/maximum coordinate calculation means B calculates the minimum and maximum coordinates for each closed contour, and it is preferable to add a means for running the recoater H at high speed in the range greater than the maximum coordinate for one closed contour and smaller than the minimum coordinate for the other closed contour. In this way, as shown in Figure 5, the recoater H runs at high speed in the range Y3 that does not actually need to be recoated, further shortening the recoating time.

The present invention will be better understood by reading the following description of the embodiments in comparison with the drawings.

[Brief Description of the Drawings] Figure 1: A diagram showing a schematic diagram of the photo-curing molding device of the present invention. Figure 2: A diagram explaining the minimum and maximum coordinates in all cross sections. Figure 3: A diagram explaining the minimum and maximum coordinates for a cross section that has just been irradiated with light and a cross section that will be irradiated with light immediately after. Figure 4: A diagram showing the magnitude of the travel distance. Figure 5: A diagram illustrating the relationship between the minimum and maximum coordinates when there are two or more closed contours. Figure 6: A system configuration diagram of an embodiment. Figure 7: A diagram explaining the data processing content. Figure 8: A configuration diagram showing the entire device of an embodiment. [Best Embodiment] Figure 8 shows a schematic diagram of the entire device of a photo-curing molding device according to one embodiment of the present invention.
indicates a liquid tank, which is filled with photocurable liquid. The photocurable liquid overflowing from the upper edge 46 is collected in the liquid tank 48, and the collected liquid is pumped up and returned to the liquid tank again.
A circulation device (not shown) is provided to return the liquid to 48, so that the liquid level is always kept at a level that coincides with the upper edge 46.

A laser oscillator 22 is disposed near the liquid tank 48, and the laser oscillator 22 emits laser light of a wavelength that cures the photo-curable liquid. The emitted laser light is filtered through an intensity adjusting filter.
The laser beam is incident on a galvanometer mirror 26 via a laser beam 24. The galvanometer mirror 26 can direct the laser beam to any desired location on the liquid surface by changing the mirror angle.
is placed on the liquid tank 48. The liquid tank 48 contains the lifting platform 42.
is disposed parallel to the liquid surface, and the lifting platform 42 is raised and lowered in the liquid tank 48 by the lifting motor 28 via the Z-direction movement mechanism 44. A recoater 38 is disposed so as to be able to run along the upper edge of the liquid tank 48 (i.e., the liquid surface), and the recoater 38 runs by the running motor 30 via the Y-direction movement mechanism 40. In the figure, 32 is an encoder that detects the rotation angle of the motor 30,
It outputs a signal relating to the position of the recoater 38.

In this embodiment, the recoater 38 has a flat lower surface that is positioned slightly higher than the liquid surface, forming a gap between the lower surface of the recoater and the liquid surface. With this recoater 38, the uncured liquid penetrates or is sucked into the gap between the lower surface of the recoater and the liquid surface by a phenomenon similar to capillary action caused by interfacial tension, so that the upper surface of the cured layer is smoothly recoated. However, the recoater is not limited to this, and
It may be a smooth plate or a brush.

In this embodiment, the rotation angle of the motor 30 is detected by the encoder 32, and the position of the recoater 38 is thereby detected.
Alternatively, a linear sensor 34 may be arranged along the travel path of the recoater 38, and the position of the recoater 38 may be detected by the linear sensor 34. Alternatively, sensors 36-1, 2, 3, ... may be arranged at predetermined intervals along the travel path, and it may be possible to detect whether the recoater 38 is present at the position corresponding to the sensor.

The signal from the encoder 32 (or the linear sensor 34 or the sensor group 36-1, 2, 3, . . . ) is input to the controller 50.
The laser oscillator 22 , the filter 24 , the galvanometer mirror 26 , the lift motor 28 , and the travel motor 30 are controlled by a controller 50 .

The system configuration of the controller 50 is shown in Figure 6. The controller 50 is composed of a computer with a central processing unit 10 as its core, and controls the members of the mechanical system shown in Figure 8 via an interface 20, and also imports data from them. The central processing unit 10 operates according to a program stored in a program storage device 12, processing data and controlling the machine, etc. The controller 50 also includes a device 14 for storing three-dimensional shape data in triangular patch format, a device 16 for storing contour data for each cross section, and a storage device 18 for minimum and maximum coordinates. This controller is used in connection with external devices that output data related to three-dimensional shapes, such as a CAD system 2 or a three-dimensional measuring device 6.

The three-dimensional shape data output from the external device is shown in FIG.
The data is converted into a triangular patch format data structure shown schematically in Figure 7(a) and stored in the three-dimensional shape data storage device 14. This data approximately defines the three-dimensional surface shape using a large number of triangles, and as is clear from Figure 7(a), the position and shape of one triangle T1 are defined by the coordinate values of points P11, P12, and P13. The positions and shapes of the other triangles T2, T3, etc. are similarly defined, and the three-dimensional shape is defined as a whole.

When data is given in this triangular patch format,
Next, the intersections C1, C2, C3, etc. between a plane and each triangle are calculated geometrically. The intersections C1, C2, C3, etc. calculated in this way are calculated geometrically.
The data defining the above is stored in a device 16 for storing contour data for each cross section. In this case, the intersection line is determined for each cross section in accordance with the amount of settling of the hardened layer per one time.

As a result, the contour data storage device 16 for each cross section stores the data shown in FIG.
The contour data shown in FIG.
Here, the left side illustrates the contour for the i-th cross section, and the right side illustrates the contour for the i+1-th cross section.

Once the contour data for each cross section is obtained in this way, the minimum and maximum coordinates in the i-th cross section and the i+1-th cross section are then calculated. As shown in Figure 7(c), the smaller of the minimum coordinates of the i-th cross section and the i+1-th cross section is set as the minimum coordinate YMIN, and the larger of the maximum coordinates of the i-th cross section and the i+1-th cross section is set as the maximum coordinate YMAX. This is calculated for all i. The YMIN(i), YMA calculated in this way are
X(i) (i=1, 2, 3 . . . ) is stored in the minimum and maximum coordinate storage device 18 .

Now, in this way, YMIN is stored in the minimum and maximum coordinate memory device 18.
When YMAX(i) and YMAX(i) are stored, the traveling motor 30 is controlled. That is, after the light irradiation for the i-th cross section is completed and the lifting platform 42 is lowered by one layer, the traveling motor 30
is rotated until the recoater 38 matches YMIN(i) or YMAX(i), and is stopped when they match. More precisely, if it was stopped at YMIN(i-1) in the previous run, it runs toward YMAX(i) and is stopped at YMAX(i), whereas if it was stopped at YMAX(i-1) in the previous run, it runs toward YAIN(i) and is stopped at YMIN(i). Note that the signal from the encoder 32 is taken in for this control. A linear sensor 34 can also be used instead of the encoder 32. In this case, the encoder 32 and the linear sensor 34
is used as a distance measurement sensor.

In this way, the travel distance or travel range of the recoater H is restricted to a range that covers, to the minimum extent possible, both the range that was previously irradiated with light and needs to be recoated, and the range that needs to be retracted so as not to interfere with the next light irradiation, thereby eliminating unnecessary travel and shortening the recoating time.

In this embodiment, the smaller the difference between the minimum coordinate YMIN and the maximum coordinate YMAX, the faster the running motor 30 is controlled to rotate.

Furthermore, as shown in FIG. 5, in the range greater than the maximum coordinate and smaller than the minimum coordinate, that is, in the range Y3 where recoating is not required, the motor 30 is controlled to rotate at high speed.

In this embodiment, the travel distance is adjusted for each layer.
However, the minimum coordinate YMIN and the maximum coordinate YMAX are calculated based on YMIN(i) and YMAX(i) (i=1, 2, . . . ), and the travel stroke of the recoater 38 is calculated based on YMIN and YMAX for all cross sections.
It may be fixed between the AX. This also has the advantage of eliminating a significant amount of unnecessary travel and simplifying the control program.

Furthermore, as shown in Figure 7(d), the closest sensor (36-2 in this case) on the side smaller than the minimum coordinate YMIN calculated in this way and the closest sensor (36-9 in this case) on the side larger than the maximum coordinate YMAX can be identified, and the recorder can move back and forth between these sensors (36-2 and 36-9 in this case).

In this way, there is no need to detect the position of the recoater using the encoder 32, linear sensor 34, etc., and control becomes extremely simple.

──────────────────────────────────────────────────── Continued from the front page (72) Inventor: Kazunori Tani 103 Vertes Nakano, 3-1-18 Tanaka-cho, Akishima-shi, Tokyo (72) Inventor: Hatsumi Naruo 610 Baham Heights Kawabe, 2-394-2 Shioka-cho, Ome-shi, Tokyo (72) Inventor: Ichitaro Sarata 12-1812 Izumi-cho, Tokorozawa-shi, Saitama (56) References: Japanese Patent Application Publication No. 4-169223 (JP, A) Japanese Patent Application Publication No. 4-118222 (JP, A) Japanese Patent Application Publication No. 114818 (JP, A)

Claims (8)

[Claims] [Claim 1] A photo-curing modeling device comprising: means for storing contour data for each cross section that defines a three-dimensional shape; means for controlling a light irradiation area on the surface of a photo-curable liquid based on the contour data stored in said means; means for sinking a hardened layer hardened by light irradiation; a recoater arranged to be able to travel along the surface of the photo-curable liquid; and recoater travel means for traveling said recoater, said device comprising: minimum/maximum coordinate calculation means for calculating the minimum and maximum coordinates of said light irradiation area relative to an axis along the traveling direction of said recoater; and a travel range of said recoater travel means based on said minimum/maximum coordinate calculation means.
a travel stroke regulating means for regulating the coordinates between the minimum and maximum coordinates calculated by the maximum coordinate calculating means; [Claim 2] The photo-curing molding device with a recoater travel stroke adjustment mechanism described in claim 1, characterized in that the minimum/maximum coordinate calculation means calculates the minimum coordinate and the maximum coordinate in the entire cross section, and the travel stroke control means uniformly controls the travel stroke in all cross-sectional layers. [Claim 3] The photo-curing molding device with a recoater travel stroke adjustment mechanism described in claim 1, characterized in that the minimum/maximum coordinate calculation means calculates the minimum coordinates and maximum coordinates for the area that was previously irradiated with light and the area that will be irradiated with light immediately after, and the travel stroke control means controls the travel stroke based on the minimum coordinates and maximum coordinates calculated for each cross section. [Claim 4] A photo-curing modeling device with recoater travel path adjustment mechanism as described in claim 1, further comprising: a group of sensors that detect the presence or absence of a recoater arranged at predetermined intervals along the travel path of the recoater; a means for identifying a pair of sensors that encompasses to the maximum extent the minimum coordinates and maximum coordinates calculated by the minimum/maximum coordinate calculation means; and a means for stopping the travel of the recoater when the recoater is detected by the identified sensor. [Claim 5] In the photo-curing modeling device with recoater travel stroke adjustment mechanism described in claim 1, the travel stroke regulating means regulates the travel stroke based on the detection value of a distance measuring sensor arranged along the travel path of the recoater. [Claim 6] A photo-curing molding device with a recoater travel stroke adjustment mechanism as described in claim 1, characterized in that a means is added to increase the recoater travel speed the smaller the difference between the minimum coordinate and the maximum coordinate calculated by the minimum/maximum coordinate calculation means. [Claim 7] The minimum and maximum coordinate calculation means calculates the minimum and maximum coordinates for each closed contour, and is characterized in that a means is added to run the recoater at high speed in a range greater than the maximum coordinate for one closed contour and smaller than the minimum coordinate for the other closed contour.This is a photo-curing molding device with a recoater travel stroke adjustment mechanism as described in claim 1. [Claim 8] A photo-curing molding device with a recoater travel stroke adjustment mechanism as described in claim 1, wherein the travel stroke regulating means regulates the travel stroke to a range that minimally encompasses the area that was previously cured by light irradiation and the area that will be irradiated with light immediately afterwards.