JPH07100941A - Internal area irradiating method in photosetting shaping method - Google Patents

Abstract

PURPOSE:To move a light beam at a high speed to reduce an irradiation time by a method wherein a line offset inward from a profile line is found, intersections of the offset line are determined, a scanning loop for connecting the intersections by the offset line is evaluated, and a light is emitted along the scanning loop when an internal area is filled with a scanning loop group. CONSTITUTION:A method comprises a first process S8 for calculating an offset line offset inward from a profile line by a predetermined distance, a second process S10 for calculating intersections of the offset line calculated in the first process, and a third process S12 for calculating a scanning loop for connecting the intersections calculated in the second process by the offset line calculated in the first process S8. The 1st-3rd processes are determined as one cycle. By repeating the cycle with the increase of an offset distance in the first process S8, a scanning loop group for an internal area of a profile is calculated. By scanning a light beam along the calculated scanning loop group, the internal area is irradiated with the light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo-curing molding method, and more particularly to a technique for improving a light irradiation process for an inner region of a contour which is frequently used when a solid model is prepared.

[0002]

2. Description of the Related Art In the photo-curing molding method, a liquid surface of a photo-curing liquid is irradiated with light in a region corresponding to a cross section of a desired molding shape. Then, the liquid surface in the light-irradiated area is photo-cured to form a cross-section hardened layer. In the photo-curing modeling method, the sectional hardened layers are successively formed in this manner, and at the same time, the newly formed sectional hardened layer is laminated and integrated with the previously formed sectional hardened layer. In this way, the cross-section hardened layers are laminated and integrated to form a three-dimensional object having the desired desired shape as a whole. The basic constitution of the photo-curing molding method is disclosed in Japanese Patent Application Laid-Open No. 56-144478.

In the photo-curing molding method, a hollow model can be molded. In this case, only the contour of the cross sectional area is irradiated with light. In this way, only the contour is hardened, and this is laminated and integrated. As a result, a hollow model in which the inside of the outer cover is empty is formed. A normal photo-curing modeling apparatus can mold both a hollow model and a solid model. When modeling a solid model, not only the contour but also the internal area surrounded by the contour is illuminated. Normally, when creating a solid model, irradiation for one cross section is handled as irradiation for the contour and irradiation for the internal region. Illuminating along the contours also has the advantage of smoothing the outer surface of the model. FIG. 2A shows a scanning line pattern for irradiating the inner region R of the contour C with light. The internal region R is irradiated with light by scanning the light beam as scanning lines a → b → c.

[0004]

Now, FIG. 2B is the same as FIG.
The moving speed of the light beam when controlled according to the scanning pattern of (A) is shown. The light beam is first accelerated while being scanned along the line a, maintains the speed when reaching a predetermined speed, decelerates when approaching the scanning limit point, and stops at the scanning limit point. After that, the scanning line b is shifted to, and similarly for the line b, acceleration → constant speed → deceleration is repeated. Therefore, the average speed of the light beam is slow, and it takes a long time to irradiate the internal region R. The present invention aims to complete the irradiation of the internal region R in a shorter time.

[0005]

According to the present invention, an offset line is formed by offsetting a contour line inward by a predetermined distance when irradiating the interior region surrounded by the contour line with a light beam by scanning with a light beam in the photo-curing molding method. And a scanning loop that connects between the intersections calculated in the second step and the second step that calculates the intersections of the offset lines calculated in the first step with the offset lines calculated in the first step. And a third step for calculating the first, second, and third steps as one cycle, and the cycle is repeated while increasing the offset distance in the first step, thereby repeating the scanning loop group for the internal region of the contour. Is calculated and a light beam is scanned along the calculated scanning loop group to irradiate the internal region with light.

[0006]

The operation of the present invention will be described with reference to FIG. Figure 4
In FIG. 1, C1 exemplifies a contour line, and in this case, the contour line C1 includes two partial contour lines C1a and C1b. In the figure, C indicates the curing range formed when the center of the light beam is scanned along the contour line C1. In the figure, L1a indicates a line in which the partial contour line C1a is offset inward by the first offset distance OF1, and L1b indicates the partial contour line C1b.
Shows a line offset by the first offset distance OF1. D1 in the figure is 2 calculated in this way
The intersection of two offset lines L1a and L1b is shown. One loop is obtained by connecting the intersections calculated in this way with an offset line. The d in FIG. 2C shows the first scanning loop calculated in this way.

In the present invention, the above cycle is repeatedly executed. At this time, the offset distance is increased. In FIG. 4, L2a and L2b indicate offset lines when the offset distance is increased to OF2 in the second cycle, and the intersection is indicated by D2. As a result, the second scanning loop e in FIG. 2 (c) is obtained. FIG. 2C illustrates a scan loop group obtained by repeating the above cycle as the third cycle and the fourth cycle. In this case, four scan loops d, e, f, g has been calculated.

In the present invention, after the scanning loop group is calculated in this way, the light irradiation of the internal region R is executed by scanning the light beam along the scanning loop. In this way, the total length of each scanning loop d, e, f, g is shown in FIG.
The length of the scanning lines a, b, c, ... Of (a) can be made significantly longer, and as shown in FIG. 2 (D), the light beam can continue to move at high speed for a long time. . In this way, according to the present invention, the time required for the light irradiation of the inner region R can be shortened.

[0009]

FIG. 1 shows an example of a processing procedure embodying the present invention. In step S2, data defining a three-dimensional shape is input to the photo-curing modeling apparatus. This data may be designed by the three-dimensional CAD system or may be given as the measurement result of the three-dimensional measuring machine. In step S4, the contour line is calculated. Note that step S4 in FIG.
Only the processing for one cross section is shown in the subsequent processing, and the processing after step S4 is actually performed for all the cross sections.

One slice when the shape input in step S2 is sliced into a plurality of layers is, for example, a CR shown in FIG.
When the radius of the light beam B is r, the contour line C1 is calculated by offsetting the divergence limit line CR inward by r. In the field of photo-curing molding method, a technique of defining a line offset by a predetermined distance is widely used.

Next, in step S6 of FIG. 1, the number of cycle repetitions K is set to an initial value "1". Next, in step S8, a line offset by the Kth offset distance is obtained, in step S10 the intersection is obtained, and in step S12, a scanning loop in which the intersections are connected by an offset line is obtained. This is as described above. Since the above processing is repeated after the execution of step S16, the second cycle is executed using the second offset distance, the third cycle is executed next using the third offset distance, and so on. Go on.

When the above processing is continued, the internal area becomes narrower in the scanning line group. Finally, the phenomenon of FIG. 7 (B) occurs. FIG. 7B shows the Kth offset distance using the Kth offset distance.
The figure shows an example when the scan loop is calculated and a case where the (K + 1) th scan loop is calculated using the (K + 1) th offset distance. As shown in FIG. 7B, when the interval G between the Kth scan loops is smaller than twice the offset distance, the rotation direction of the scan loop (K + 1th scan loop in this case) to be obtained next is reversed. In FIG. 7B, the Kth scan loop is clockwise, while the K + 1th scan loop is counterclockwise. This phenomenon occurs when the inner area is filled with the scan loop group.

If step S14 is YES, step S18 and subsequent steps are executed to actually irradiate light. In this case, in step S18, the Kth scan loop is first scanned, then the K-1th scan loop is scanned, the scan loop is similarly scanned thereafter, and finally the first scan loop is scanned (step S18). S20), the contour is finally scanned (step S22). As a result, the scanning loop group is sequentially obtained from the contour toward the inside, and the actual irradiation is sequentially performed from the inside toward the outside. In this way, a hardened layer with less distortion can be formed, and the outer surface of the contour can be made smooth.

FIG. 3 shows the scan loop group obtained in this way. In the figure, OC is the outer contour,
IC is the inner contour. In the figure, 1 is the first scanning loop, 2
Shows the second scanning loop, and so on. In this case, from the outside contour OC side as well as the inside contour IC side,
By finding the offset line and starting to intersect it (beginning to intersect at the third offset line in this example), by connecting the intersection points with the offset line,
The scanning loops indicated by 3, 4, 5 ... In this way, the scanning loop group covering the internal region is calculated by the processing of FIG. 1 for all the cross sections.

FIG. 3 shows a case where the diameter of the laser beam for irradiating the contour is the same as the diameter of the laser beam for irradiating the inner region. In this case, set the offset distance to the beam diameter 2r.
When it is equal to, a non-irradiated region US is generated in the corner portion as shown in FIG. In order to avoid this, the radius of the laser beam may be increased 1.4 times when irradiating the internal area. In this way, no unirradiated area remains. On the contrary, as shown in FIG. 5, the offset distance is set to 2r /
(2) It may be ^1/2 . In this way, the unirradiated area can be eliminated without changing the beam diameter.

FIG. 6 shows another embodiment. In this case, the calculation of the seventh, ninth and eleventh scanning loops is omitted. That is, the offset distance is increased in the innermost part of the inner region. Instead, when the offset distance is increased, the radius of the light beam is
Double. In this way, the light irradiation time inside the scanning loop 6 is almost halved. Further, the degree of curing inside the scanning loop 6 can be made lower than other portions, and the degree of curing stress generated inside the scanning loop 6 can be reduced. If the degree of photo-curing in the area 6 is too low, the required exposure amount can be adjusted by lowering the scanning speed in the scanning loops 6, 8, 10, 12.

As described with reference to FIG. 7 (B), if the scanning loop direction is reversed by offsetting the scanning loop further inward than the innermost scanning loop, in the processing procedure of FIG. Loop (K + 1 in Figure 7 (B))
Only the light is illuminated, and the scanning loop is not calculated any further. Instead, as shown in Fig. 7 (A),
A line 71 for scanning the center of the last unirradiated area 70
May be calculated. Further, the beam diameter at this time may be matched with the width of the unirradiated region 70. With these techniques, the time required for irradiation of the internal area can be shortened.
Further, it is possible to make the exposure amount of the inner region uniform, or to make the intensity stronger and weaker for each place.

[0018]

According to the present invention, since the scanning loop is determined by the process of repeating the offset, the total length of the scanning loop can be secured long, and therefore the light beam can be continuously moved at high speed. Become. As a result, the time required for light irradiation of the internal region is shortened. The offset process is a technique that is normally used in the photo-curing modeling method, and is indispensable for calculating contour lines and the like. The present invention can utilize a program for calculating a contour line,
Software development is also facilitated.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a processing procedure embodying the present invention.

FIG. 2 is a diagram comparing a scan loop of the present invention with a conventional one.

FIG. 3 is a diagram showing an example of a scanning loop of the present invention.

FIG. 4 is a diagram showing an offset line and an example of an intersection.

FIG. 5 is a diagram showing an influence of an offset distance.

FIG. 6 is a diagram showing another example of a scanning loop.

FIG. 7 is a diagram showing an innermost scanning loop.

[Explanation of symbols]

 S8 1st process S10 2nd process S12 3rd process Returning from S16 to S8 Loop cycle repeating process

Claims (1)

[Claims] 1. A first step of calculating an offset line offset by a predetermined distance inside a contour line when irradiating light by scanning a light beam on an inner region surrounded by the contour line by a photo-curing molding method. A second step of calculating the intersection of the offset lines calculated in the first step, and a third step of calculating a scanning loop connecting the intersections calculated in the second step with the offset line calculated in the first step. The first, second, and third steps are defined as one cycle, and the first
By repeating the cycle while increasing the offset distance in the process, the scanning loop group for the internal area of the contour is calculated, and the internal area is irradiated with light by scanning the light beam along the calculated scanning loop group. Internal area irradiation method in the photo-curing modeling method.