Fold line design method, design device, and non-transitory computer readable medium

1 . A method of designing a fold line for folding a target member, comprising:

setting a ribbase on a plane along a main surface of the target member;

designing a plurality of first fold lines each of which extend radially from the ribbase as a starting point, and in which a mountain fold line and a valley fold line are alternately disposed;

designing a plurality of second fold lines which respectively connect the first fold lines adjacent to each other among the plurality of first fold lines, and constitute one continuous fold line;

correcting the plurality of second fold lines so that a rotation axis of the target member when being folded becomes different between the plurality of the second fold lines after designing of the plurality of second fold lines; and

in correspondence with the correction, correcting fold lines on a side far away from the ribbase in comparison to intersection points with the second fold lines in each of the plurality of first fold lines.

2 . The method of designing a fold line according to claim 1 , wherein the plurality of first fold lines includes

a plurality of mountain fold lines that extend radially from different starting points on the ribbase, and

a plurality of valley fold lines that extend radially between the mountain fold lines adjacent to each other from the starting points of the plurality of mountain fold lines.

3 . The method of designing a fold line according to claim 1 , wherein in designing of the plurality of first fold lines and in designing of the plurality of second fold lines, a reference line provided on an outer side of the ribbase is set, and with respect to each straight line extending from the starting point of each of the plurality of mountain fold lines toward the reference line, an intersection point with the reference line is set for each of the starting points, and design is performed by using a straight line connecting the starting point and the intersection point of the reference line.

4 . The method of designing a fold line according to claim 2 , wherein designing of the plurality of first fold lines includes

drawing of a straight line connecting each of the starting points of the plurality of mountain fold lines on the ribbase and a reference point provided on an outer side of the ribbase, and

drawing a fold line obtained by arranging the straight line to be line-symmetric with respect to a line connecting the starting point and an additional starting point adjacent to the starting point, and

wherein designing of the plurality of second fold lines includes setting of a reference line between the ribbase and the reference point, and setting of intersection points between the second fold lines and the plurality of mountain fold lines on the basis of a distance between each starting point of the straight line on the ribbase and an intersection point between the reference line and the straight line.

5 . The method of designing a fold line according to claim 1 ,

wherein designing of the plurality of second fold lines includes designing of the plurality of second fold lines so that in each of the plurality of mountain fold lines included in the plurality of first fold lines, an angle made by two pieces of the second fold lines connected to the mountain fold line is equal in each case, and in each of the plurality of valley fold lines included in the plurality of first fold lines, an angle made by two pieces of the second fold lines connected to the valley fold line is equal in each case.

6 . The method of designing a fold line according to claim 5 , wherein after folding, the plurality of first fold lines are corrected so that facet edges of creases along the plurality of first fold lines are parallel to each other on a side far away from the ribbase in comparison to the second fold lines.

7 . The method of designing a fold line according to claim 5 , wherein after folding, the plurality of first fold lines on a side far away from the ribbase in comparison to the second fold lines are corrected so that facet edges of creases along the plurality of second fold lines are angled to be separated from each other at approximately the same interval.

8 . A design device configured to design a fold line for folding a target member, comprising:

an input device unit configured to input information relating to a shape of the target member;

at least one processor configured to design the fold line on the basis of the information inputted by the input device; and

an output device configured to output a result designed by the at least one processor,

wherein the at least one processor is configured to:

set a ribbase on a plane along a main surface of the target member,

design a plurality of first fold lines each of which extend radially from the ribbase as a starting point, and in which a mountain fold line and a valley fold line are alternately disposed,

design a plurality of second fold lines which respectively connect the first fold lines adjacent to each other among the plurality of first fold lines, and constitute one continuous fold line,

correct the plurality of second fold lines so that a rotation axis of the target member when being folded becomes different between the plurality of the second fold lines after designing of the plurality of second fold lines, and

in correspondence with the correction, correct fold lines on a side far away from the ribbase in comparison to intersection points with the second fold lines in each of the plurality of first fold lines.

9 . A non-transitory computer readable medium storing a design program causing a computer to function as a design device configured to design a fold line for folding a target member, comprising:

a shape information acquisition function of acquiring information relating to a shape of the target member;

a design function of designing the fold line on the basis of the information acquired by the shape information acquisition function; and

an output function of outputting a result designed by the design function, wherein the design function performs

setting a ribbase on a plane along a main surface of the target member,

designing a plurality of first fold lines each of which extend radially from the ribbase as a starting point, and in which a mountain fold line and a valley fold line are alternately disposed,

designing a plurality of second fold lines which respectively connect the first fold lines adjacent to each other among the plurality of first fold lines, and constitute one continuous fold line,

correcting the plurality of second fold lines so that a rotation axis of the target member when being folded becomes different between the plurality of the second fold lines after designing of the plurality of second fold lines, and

in correspondence with the correction, correcting fold lines on a side far away from the ribbase in comparison to intersection points with the second fold lines in each of the plurality of first fold lines.