WO1995002500A1

WO1995002500A1 - Photo-curing modeling apparatus equipped with offset function of tessellation data, and offset method

Info

Publication number: WO1995002500A1
Application number: PCT/JP1993/000997
Authority: WO
Inventors: Seiji Hayano
Original assignee: Cmet, Inc.
Priority date: 1993-07-15
Filing date: 1993-07-15
Publication date: 1995-01-26

Abstract

This invention relates to a photo-curing modeling apparatus for modeling a three-dimensional shape by inputting tessellation data defining a three-dimensional shape, calculating a profile data for each section on the basis of the tessellation data and controlling a light irradiation region on the basis of the profile data calculated. This apparatus includes means for storing the tessellation data, means for calculating a normal vector at the apex of each tessellation data, means for judging whether the normal vector calculated has a direction extending along the light irradiation direction or an opposite direction, means for offsetting the coordinates of the apex, which is judged as having the normal vector in the light irradiation direction by the judgement means, in the light irradiating direction, and means for calculating the profile data for each section on the basis of the tessellation data thus offset. The shape before offsetting can be accurately embodied.

Description

Specification

[Title of Invention]

Light curing molding machine with offset function for tessellation data and offset method [Technical field]

The present invention relates to a photocuring molding technique, and more particularly to a technique for improving the shape accuracy of a molded article.

[Background technology]

With the spread of 3D CAD and 3D measuring machines, opportunities to handle data defining L and 3D shapes are increasing. There is a well-known technology for defining a shape using tessellation data in one form of defining a three-dimensional shape. Figure 1 is a diagram schematically showing this technology, and illustrates the contents of the telesegmentation that defines the three-dimensional shape indicated by reference numeral 10 that exists in the X-Y-Z coordinate system. are doing.

In general, a three-dimensional shape can be approximately represented as a set of tessellations 1, 2, 3,... The position and shape force of each tessellation is defined by the coordinates of the vertex. Figure 1 illustrates the case where each tessellation is a triangle.If each tessellation is a triangle, three vertices belonging to each tessellation, for example, for tessellation 2, the vertices 2 1 2 2 The position and the shape force are defined by the coordinates. The coordinates of each vertex are given by (X, y, z) components. In this way, a three-dimensional shape 10 is defined by a set of coordinates of the vertices of each tessellation.

The shape itself is defined by the set of vertex coordinates. However, it is still undefined whether the defined shape, for example, 10 is a solid object or an empty hole. Therefore, each tessellation is provided with a normal vector. FIG. 1 shows an example in which the normal vector 24 of the tessellation 2 goes from inside to outside of the shape 10. The normal vector has the regularity that the object force moves from the existing side to the non-existing side. I understand. On the other hand, if the normal vector 24 force << going from outside to inside, it turns out that the shape 10 defines a hole, not an object. From the above, the three-dimensional shape is defined as a set of data indicating the coordinates of the vertices of each tessellation and the normal vector of each tessellation (this is called tessellation data). become. Although FIG. 1 shows the case of each triangulation force triangle, it may be defined by a polygon.

Even if a three-dimensional shape is defined in the tessellation data, there is no real thing with the defined shape. Therefore, in order to represent the shape defined by the data as an extractable material, a photo-curing molding technology has been developed. Figure 2 is a diagram schematically showing the technology. In the photo-curing molding technology, a liquid resin 25 that cures when irradiated with light, a substrate 26 that forms the basis of the molded article, and an irradiation device 20 that can control the light irradiation area are used. First, the substrate 26 is immersed at a predetermined distance Z from the liquid surface 27 of the liquid resin 25. In this state, the liquid level 27 is irradiated by the irradiation device 20. The irradiation area at this time is defined as the inside of the contour 28 in the lowest section of the three-dimensional shape 10 defined by the tessellation data. The irradiation intensity is set so that the liquid 25 can be cured from the liquid surface 27 to a depth ΔΖ. Then, a cured layer 28 a having a contour Δ 28 and a thickness Δ Ζ is formed on the substrate 26.

Next, the substrate 26 is sunk by ΔΖ, and the inside of the contour 29 in the cross section above by ΔΖ in the three-dimensional shape 10 is irradiated with light. Then, on the previously formed hardened layer 28 a, a hardened layer 29 3 having a thickness Δ 対応 corresponding to the contour 29 is formed, and both hardened layers 28 a and 29 a are integrated. .

By repeating this process, a cured product is formed in the liquid 25, and the cured product has a shape 10 defined by tessellation data.

The above example is an example of photo-curing molding technology, and there are various methods such as a method of irradiating light from the bottom and pulling up the substrate, and a method of fixing the substrate and raising the liquid level. Existing.

This photo-curing molding technology is extremely useful because the three-dimensional shape defined by Tessellation de can be automatically converted into a tool.

In the case of photocuring molding technology, the following two points affect the shape accuracy. In controlling the light irradiation area, there is a method that regulates the scanning range of the light beam. In this method, the contour is traced by a light beam. In this case, as shown in FIG. If the center force is moved along the contour 30, the light beam 31 will be hardened to the outside of the contour 30 by the radius r of the light beam 31, and the object will be more outward than the desired shape. It becomes big.

To solve this problem, it is effective to offset the moving line of the light beam inside the object by the radius r of the light beam. In this way, the contour of the cured product matches the contour of the desired shape.

Even when offsetting by the radius r, the following problem still exists. Figure 4 illustrates this. If the shape to be shaped is shown as 40, and it is overhanging to the side at the top, first irradiate the inside of contour 45, then layer the liquid, and then irradiate the inside of contour 44. The process of laminating the liquid later is repeated. As a result, in the portion that protrudes outward, as shown by a hatched portion 46 in the figure, the portion becomes excessively thicker by the hardening depth d.

Techniques for addressing this problem are shown in International Publication WO92 / 02008. This technique shows a technique that uses the contour of the lower layer to determine the irradiation area. Explaining along the example of Fig. 5, when determining the irradiation area at level 54, not only the cross section at level 54 but also the cross section at level 55 is considered, The irradiation area is determined by the lean product. In the case illustrated in FIG. 5, since the cross-sectional area at level 55 is included in the cross-sectional area at level 54, the pulley product becomes the cross-sectional area at level 55, and eventually the overhang at level 54. Will not be irradiated. As a result, the problem of the extra hardened portion 46 shown in FIG. 4 can be prevented.

[Disclosure of the Invention]

Now, suppose 67 in FIG. 6A is defined by the tessellation data. In this case, if the conventional technology, that is, the irradiation area of the upper layer is determined in consideration of the contour of the lower layer, the modeled object is as shown in Fig. 6 (B), which is different from that of Fig. 6 (A). For example, if the level 60 irradiation area is determined by the Brillouin product of the level 60 contour and the level 61 contour, the level 61 contour will determine the level 60 irradiation area. If modeling is performed in the area, the shape indicated by 69 in the figure will be molded. That is, the portion indicated by 68 in the figure is missing. The present invention solves the above problem. It never improves the shape accuracy of the modeled object.

The light-curing modeling apparatus according to the present invention inputs tessellation data that defines a three-dimensional shape, calculates contour data for each cross section based on the tessellation data, and converts the contour data into calculated contour data. The three-dimensional shape is formed by controlling the light irradiation area on the basis of the light irradiation area, and as shown schematically in FIG. 7, means 71 for storing tessellation data, and A means 72 for calculating a normal vector at the vertex is provided.

The normal vector at a vertex is calculated by synthesizing the normal vector of the tessellation to which the vertex belongs. For example, the vertex 80 shown in FIG. 7 commonly belongs to the six tessellations 81 to 86, and thus the normal vector 8 ON of the vertex 80 is 81 to 86. Is calculated as a composite vector of each normal vector 81 N to 86 N of each tessellation.

According to one aspect of the present invention, means for determining the direction of the calculated normal vector

7 3 is added. The orientation is determined according to FIG. In FIG. 8, the Z direction is the light irradiation direction, and ZH is a plane orthogonal to the direction. When the normal vector N faces the lower side of the plane ZH in the figure, the direction is along the light irradiation direction, and when the normal vector N points in the upper side of the figure, the direction is opposite.

This apparatus uses a direction discriminating means 73 to set the coordinates of the vertex having a normal vector in the direction along the light irradiation direction in the light irradiation direction in the direction opposite to the light irradiation direction, that is, as shown in FIG. Means 74 for offsetting by the curing depth in the direction of ZA. Here, the curing depth d is a depth indicated as d in FIGS. 3 and 4, and is a depth at which curing is performed by scanning with a light beam. In other words, when light is irradiated at the offset coordinates, the curing force advances to the coordinates before the offset. The offset process is not performed on the vertex in the direction opposite to the direction of normal vector light irradiation of the vertex.

According to another aspect of the present invention, a means for calculating a vector component in a plane orthogonal to the light irradiation direction of the normal vector and a coordinate in a plane orthogonal to the light irradiation direction of the vertex are calculated. Means for offsetting by the curing radius in the direction opposite to the direction defined by the vector component are provided. Here, the curing depth is indicated by r in Fig. 3. --Indicates radius. In this case, offset processing is performed for all vertices regardless of the type of vertices.

In the case of the present invention, means for storing the tessellation data offset by means 74 and Z or means 78 is provided, and means for calculating the contour for each section based on this data is provided. 6 and means 77 for controlling the light irradiation area based on the contour data calculated by the means 76.

Means 74 When the force is applied, the vertex of each tessellation on the surface facing the light irradiation direction is offset in the direction opposite to the light irradiation direction. Therefore, if the irradiation area is controlled based on the offset coordinates, the lower end of the hardened part will match the coordinates before the offset, and the shape of the modeled object will be the shape defined by the tessellation data before the offset. Well approximate. Note that for the surface oriented in the opposite direction to the light irradiation direction, the accuracy reduction described in FIGS. 5 and 6 does not pose a problem, and no offset is required. In addition, when means 78 are provided, the movement trajectory of the light beam is offset to the inside of the contour, and the problem of FIG. 3 is solved.

The present invention will be better understood with reference to the following examples and drawings.

[Brief description of drawings]

Fig. 1 Diagram illustrating an example and contents of telemetry data

Figure 2 Diagram showing conventional photocuring molding technology

Figure 3 Diagram showing the problem of the hardened layer expanding outward in the radial direction

Figure 4 Diagram showing the problem of excessive growth of the hardened layer in the light irradiation direction

Figure 5 Diagram illustrating the traditional approach to addressing the problem of Figure 4

Figure 6 Diagram explaining the problem with the method of Figure 5

Fig. 7 Diagram schematically showing an example of the present invention

Fig. 8 Diagram showing the relationship between the light irradiation direction and the normal vector

Figure 9 Diagram explaining the operation of the present invention

Figure 10 Diagram explaining the operation of the present invention

Figure 11 Diagram illustrating the overall system of one embodiment

Figure 1 2 Diagram explaining the operation of the system according to Figure 11

[Best Mode for Carrying Out the Invention] FIG. 11 shows a system configuration of a photocuring modeling apparatus incorporating the present invention. In the figure, reference numeral 110 denotes a memory device for storing memory of the tessellation data before the offset and an area for storing memory of the tessellation data after the offset 1 1 2 It has an area 113 for storing d and r and curing parameters, and an area for storing various control programs.

The hardening parameters d and r are shown in Fig. 12, and store the radius r and depth d that are hardened as the laser beam travels. Since the curing radius r and the curing depth d are different depending on the intensity, radius, running speed, and resin used of the laser beam, d and 1 ″ are stored in the area 113 under various conditions.

The control program storage area 114 stores a program for inputting the tessellation data sent from the 3D CAD and storing it in the area 111. By executing this program, the program shown in FIG. Tessellation data is stored in area 1 1 1; f o

In the control program storage area, a program for executing the following contents is stored.

(1) Extraction of tessellation that shares vertices

This program extracts the tessellation to which all vertices belong. For example, for vertex 80 in FIG. 7, tessellation 81 to 86 is extracted.

(2) Calculation of the normal vector of the vertex

The normal vector at the vertex is calculated by vector addition of the normal vector of the tessellation extracted by the program (1).

(3) Determining the direction of the normal vector

The Z-direction component N z is extracted from the normal vector N calculated by the program (2) (see FIG. 12). Here, the Z direction coincides with the light irradiation direction. If the extracted Z-direction component N z force has a positive value, the normal vector of the vertex is the direction along the light irradiation direction, and if it has a negative value, the normal vector of the vertex is In the opposite direction.

(4) Offset processing in the Z direction For the vertices having the normal vector in the direction along the light irradiation direction in the program of (3), the coordinates of the irradiation direction (for example, the vertex 21 in FIG. Subtracts d from z 2 1). As a result, the offset coordinates indicate coordinates that are offset from the coordinates before the offset by d (hardening depth) in a direction opposite to the light irradiation direction. This offset is not performed for vertices whose Z direction component calculated by program (3) is negative and whose direction is opposite to the light irradiation direction.

(See equation (4) in Fig. 12).

(5) Offset in X, y plane

In this program, offset processing is performed according to equations (1) and (2) in Fig. 12. In FIG. 12, N xy is a component in the plane xy of the normal vector N, N x is an X component of N xy, and y is a y component of N xy. In equations (1) and (2), N x, N y, and N z indicate the magnitude of the vector. In Equations (1) and (2), N xy is a vector component in a plane (xy plane) orthogonal to the light irradiation direction Z of the normal vector N calculated by the program (2). By executing (2), the coordinates of the vertices in the xy plane will be offset by the hardening radius r in the direction opposite to the vector N xy. As a result, the problem shown in FIG. 3 is solved and the light beam comes into contact with the external force profile. This is better understood by FIG.

Now, the tessellations thus offset are remembered in the area 1 12 in FIG. Then, from that moment, the contour force << for each section is extracted. As a result, when the light beam is scanned along the contour calculated as shown in Fig. 9, the extension hardened by the light beam approximates the shape defined by the tessellation before the offset. Is obtained.

Thus, according to this embodiment, the shape accuracy is improved both in the xy plane and in the z direction.

If the shape as shown in FIG. 9, that is, the shape that extends to the side as it goes upward, is not formed at all, all the apex forces are upward. In such a case, the offset means in the Z direction does not function even if present, and therefore, the offset means in the Z direction can be omitted. When the radius of the light beam is sufficiently small and r in FIG. 12 can be almost neglected, the offset processing of equations (1) and (2) may be omitted.

Claims

The scope of the claims

1. Enter the tessellation data that defines the three-dimensional shape, calculate the contour data for each section based on the tessellation data, and control the light irradiation area based on the calculated contour data. A light-curing modeling apparatus for modeling a three-dimensional shape, and means for storing the tessellation data,

Means for calculating the normal vector at the vertex of each tessellation;

Means for determining whether the calculated normal vector is directed along the light irradiation direction or the opposite direction;

It has been determined that the discriminating means has a normal vector in the direction along the light irradiation direction] ¾, wherein the coordinates of the light irradiation direction are offset by the curing depth in a direction opposite to the light irradiation direction,

A photocuring molding apparatus comprising means for calculating contour data for each section based on offset tessellation data.

2. In the light-curing modeling apparatus according to claim 1, the normal vector calculating means calculates a normal vector at a vertex by a vector synthesis of the normal vector of each tessellation to which the vertex belongs. Photocuring, characterized in that it calculates the vector

3. Enter the tessellation data that defines the three-dimensional shape, calculate the contour data for each section based on the tessellation data, and control the light irradiation area based on the calculated contour data. A light-curing modeling apparatus for modeling a three-dimensional shape by means of storing the tessellation data;

Means for calculating the normal vector at the vertex of each tessellation;

Means for calculating a vector component in a plane orthogonal to the light irradiation direction of the calculated normal vector;

Means for offsetting the coordinates in a plane perpendicular to the light irradiation direction of the vertex by a curing radius in a direction opposite to the calculated vector component;

A photocuring molding apparatus comprising means for calculating contour data for each cross section based on offset tessellation data.

4. In the light-curing modeling apparatus according to claim 3, the normal vector calculating means calculates a normal vector at the vertex by a vector synthesis of the normal vector of each tessellation to which the vertex belongs. A photo-curing molding apparatus for calculating a vector.

5. Enter the tessellation data that defines the three-dimensional shape, calculate the contour data for each section based on the tessellation data, and control the light irradiation area based on the calculated contour data. A light-curing modeling apparatus for modeling a three-dimensional shape, and means for storing the tessellation data,

Means for calculating the normal vector at the vertex of each tessellation;

Means for offsetting the coordinates of the light irradiation direction of the apex determined to have a normal vector in the direction along the light irradiation direction by the curing means in the direction opposite to the light irradiation direction by the curing depth,

Means for offsetting coordinates in a plane perpendicular to the light irradiation direction of the apex by a curing radius in a direction opposite to the calculated vector component,

A photocuring molding apparatus, comprising: means for calculating contour data for each cross section based on offset tesselation data.

6. In the photo-curing modeling apparatus according to claim 5, the normal vector calculating means calculates a normal vector of the vertices by combining vectors of the normal vectors of each tessellation to which the vertex belongs. Photocuring molding characterized by calculating a line vector

7. Offset the tessellation data used in the light irradiation area calculation process of the light-curing modeling method to change the shape of the molded object formed by the light-curing modeling method to the shape defined by the tessellation data before offset. Is a method of approximation,

Calculating a normal vector at the vertex of each tessellation;

Light irradiation direction of the vertex, which is the direction along the calculated normal vector light irradiation direction Offsetting the coordinates of by the curing depth in the direction opposite to the light irradiation direction,

Calculating a vector component in a plane perpendicular to the light irradiation direction of the calculated normal vector;

A method of offsetting coordinates of a vertex in a plane orthogonal to a light irradiation direction by a curing radius in a direction opposite to the calculated vector component.