JP3342125B2 - Internal area irradiation method in light curing molding method - Google Patents

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 step on an inner region of a contour often used when a solid model is created.

[0002]

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

[0003] In the light curing molding method, a hollow model can be formed. In this case, only the outline of the cross-sectional area is irradiated with light. By doing so, only the outline is hardened, and this is laminated and integrated. As a result, a hollow model in which the inside of the outer skin is empty is formed. An ordinary photocuring molding apparatus can mold both a hollow model and a solid model. When forming a solid model, not only the outline, but also the internal region surrounded by the outline is irradiated with light. Normally, when a solid model is created, irradiation on one cross section is handled separately as irradiation on a contour and irradiation on an internal region. Irradiating light along the contour also has the advantage of smoothing the outer surface of the model. FIG. 2A shows a pattern of a scanning line for irradiating the inner region R of the contour C with light. The light irradiation on the internal region R is performed by scanning the light beam in the order of the scanning lines a → b → c.

[0004]

FIG. 2B is a block diagram of FIG.
3A illustrates the moving speed of the light beam when controlled according to the scanning pattern of FIG. The light beam is first accelerated when scanning along the line a, maintains the speed when it reaches a predetermined speed, decelerates when approaching the scanning limit point, and stops at the scanning limit point. Thereafter, the scanning line is shifted to the scanning line b, and the acceleration, the constant speed, and the deceleration of the line b are similarly repeated. For this reason, the average speed of the light beam is low, and it takes a long time to irradiate the internal region R. The present invention is intended to complete the irradiation of the internal region R in a shorter time.

[0005]

According to the present invention, when irradiating a light beam by scanning a light beam in an inner region surrounded by a contour line by a light curing molding method, an offset line in which the contour line is offset inward by a predetermined distance. , A second step of calculating the intersection of the offset lines calculated in the first step, and a scanning loop connecting the intersections calculated in the second step with the offset line calculated in the first step A scanning loop group for the inner region of the contour by repeating the cycle while increasing the offset distance in the first step, wherein the first, second, and third steps are defined as one cycle. Is calculated, and the inner region is irradiated with light by scanning the light beam along the calculated scanning loop group.

[0006]

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

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 intersections thereof are indicated by D2. As a result, the second scanning loop shown in e in FIG. 2C is obtained. FIG. 2C illustrates a scan loop group obtained by repeating the above-described cycle as a third cycle and a fourth cycle. In this case, four scan loops d, e, f, and g has been calculated.

In the present invention, after the scan loop group is calculated in this manner, light irradiation of the internal region R is performed by scanning the light beam along the scan loop. In this manner, the total length of each of the scanning loops d, e, f, and g is shown in FIG.
(a) can be made much longer than the length of each of the scanning lines a, b, c,..., and as shown in FIG. . Thus, according to the present invention, the time required for light irradiation of the internal region R can be reduced.

[0009]

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

One cross section obtained by slicing the shape input in step S2 into a plurality of layers is, for example, a CR shown in FIG.
And the radius of the light beam B is r, the contour C1 is calculated by offsetting the spread limit line CR inward by r. In the field of photocuring molding, a technique of defining a line offset by a predetermined distance is often used.

Next, in step S6 of FIG. 1, the number K of cycle repetitions is set to an initial value "1". Next, a line offset by the K-th offset distance is obtained in step S8, the intersection is obtained in step S10, and a scanning loop connecting the intersections with an offset line is obtained in step S12. 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, and then the third cycle is executed using the third offset distance. Go on.

As the above processing is continued, the internal area becomes narrower in the scanning line group. Finally, the phenomenon shown in FIG. 7B occurs. FIG. 7 (B) illustrates the K-th offset using the K-th offset distance.
2 illustrates a case where a scan loop is calculated and a case where a (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 K-th scan loops is smaller than twice the offset distance, the rotation direction of the next scan loop (in this case, the (K + 1) -th scan loop) is reversed. In FIG. 7B, the K-th scanning loop is clockwise, while the K + 1-th scanning loop is counterclockwise. This phenomenon occurs when the internal area is filled by the scan loops.

If step S14 results in YES, then step S18 and subsequent steps are executed to actually irradiate light. In this case, in step S18, the K-th scanning loop is scanned first, then the (K-1) -th scanning loop is scanned, the scanning loop is scanned in the same manner, and finally the first scanning loop is scanned (step S18). S20), the contour is scanned last (step S22). As a result, the scan loop groups are obtained in order from the contour to the inside, and the actual irradiation is performed from the inside to the outside in order. By doing so, a hardened layer with less distortion can be formed, and the outer surface of the contour can be smooth.

FIG. 3 shows a scan loop group obtained in this manner. In the figure, OC is the outer contour,
IC is the inner contour. In the figure, 1 is a first scanning loop, 2
Shows a second scanning loop, and so on. In this case, the K-th position is used from both the outer contour OC and the inner contour IC.
After the offset line is determined and begins to intersect (in this example, begins to intersect at the third offset line), by connecting the intersections with an offset line,
Scan loops indicated by 3, 4, 5,... In the figure are obtained. In this way, a scan loop group covering the internal area is calculated for all the cross sections by the processing of FIG.

FIG. 3 shows a case where the diameter of the laser beam for irradiating the contour is equal to the diameter of the laser beam for irradiating the inner region. In this case, the offset distance is set to the beam diameter 2r.
As shown in FIG. 4, a non-irradiated area US occurs at the corner as shown in FIG. In order to avoid this, the radius of the laser beam may be increased by a factor of 1.4 when irradiating the internal region. In this way, no unirradiated area remains. Alternatively, conversely, as shown in FIG.
(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. In other words, the offset distance is increased for the innermost part of the inner area. Instead, when the offset distance is increased, the radius of the light beam is changed to another two.
Double it. In this way, the light irradiation time inside the scanning loop 6 is reduced by almost half. Further, the degree of hardening inside the scanning loop 6 can be made lower than other portions, and the degree of hardening stress generated inside the scanning loop 6 can be reduced. If the photocuring degree in the region 6 is too low, the required exposure amount can be adjusted by lowering the scanning speed in the scanning loops 6, 8, 10, and 12.

As described with reference to FIG. 7B, if the direction of the scanning loop is reversed when it is further offset from the innermost scanning loop, the processing procedure of FIG. Loop (K + 1 in Fig. 7 (B))
Only the light is radiated, and no scan loop is calculated beyond that. Instead, as shown in FIG. 7 (A),
A line 71 that scans the center of the last unirradiated area 70
May be calculated. Further, the beam diameter at this time may be adjusted to the width of the non-irradiated area 70. With these techniques, the time required for irradiating the internal region can be reduced.
Further, for example, it is possible to make the exposure amount of the internal region uniform, or to add strength to each location.

[0018]

According to the present invention, since the scanning loop is determined by the process of repeating the offset, the entire length of the scanning loop can be secured long, and therefore, it is possible to keep moving the light beam at high speed. Become. As a result, the time required for light irradiation of the inner region is reduced. The offset processing is a technique usually used in the photo-curing molding method, and is indispensable for calculating a contour line or the like. The present invention can use a program for calculating a contour line,
Software development is also facilitated.

[Brief description of the drawings]

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

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

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

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

FIG. 5 is a diagram showing the 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 First step S10 Second step S12 Third step Loop returning from S16 to S8 Cycle repeating step

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 67/00

Claims (1)

(57) [Claims] A first step of calculating an offset line in which the contour is offset inward by a predetermined distance when irradiating light by scanning a light beam in an inner region surrounded by the contour in a light curing molding method; A second step of calculating an 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. Wherein the first, second, and third steps are defined as one cycle,
By repeating the above cycle while increasing the offset distance in the process, a scan loop group for the inner region of the contour is calculated, and the inner region is irradiated with light by scanning the light beam along the calculated scan loop group. Area irradiation method in photocuring molding method.