Rail support device and sheet stretching method

A rail support device installed in a clip chain type sheet stretching apparatus configured to hold an end portion in a transverse direction of a sheet by using clips of clip chains, and to stretch the sheet while conveying the sheet by running the clip chains in a horizontal direction along a rail, the rail support device configured to support the rail and comprising:

• a first rail support member configured to support a first straight portion of the rail;
• a second rail support member configured to support a second straight portion of the rail in a direction intersecting the first straight portion;
• and
• an arc shaped rail support member configured to support an arc shaped portion of the rail connecting the first and second straight portions to each other, wherein
• the first rail support member includes a first connecting portion and a first straight rail support portion being a portion other than the first connecting portion,
• the second rail support member includes a second connecting portion and a second straight rail support portion being a portion other than the second connecting portion,
• the first connecting portion and the second connecting portion are engaged with each other,
• the second rail support is rotatable relative to the first rail support member about a first axis extending in a vertical direction at the first and second connecting portions,
• the first and second rail support members respectively support the first and second straight portions by the first and second straight rail support portions with longitudinal directions of the first and second rail support members respectively set to coincide with longitudinal directions of the first and second straight portions,
• the arc shaped rail support member is engaged with at least one of the first connecting portion and the second connecting portion to form a higher pair so as to rotate relative to the at least one connection portion about the first axis and to move relative to the at least one connection portion along a first straight line passing through the first axis and extending in the horizontal direction,
• the arc shaped rail support member is engaged with the first connecting portion to form a higher pair so as to rotate relative to the first connecting portion about a second axis extending in the vertical direction at the first connecting portion and to move relative to the first connecting portion along a second straight line passing through the second axis and extending in the horizontal direction,
• the arc shaped rail support member is engaged with the second connecting portion to form a higher pair so as to rotate relative to the second connecting portion about a third axis extending in the vertical direction at the second connecting portion and to move relative to the second connecting portion along a third straight line passing through the third axis and extending in the horizontal direction,
• the first axis exists in an intersection angle bisecting plane developing in the vertical direction and including an intersection angle bisector being a straight line passing through an intersection point between an extended line of the first straight portion and an extended line of the second straight line and extending in the horizontal direction while bisecting an intersection angle of the extended lines of the first and second straight portions,
• the arc shaped rail support member supports the arc shaped portion of the rail in the intersection angle bisecting plane,
• the first straight line extends in a direction of extension of the intersection angle bisector,
• the first rail support member and the second rail support member are symmetrical to each other with respect to the intersection angle bisecting plane,
• the second straight line extends in the horizontal direction intersecting with the intersection angle bisecting plane, and
• the third straight line and the second straight line are symmetrical to each other with respect to the intersection angle bisecting plane.

A method for stretching a sheet comprising:

• preparing a clip chain type sheet stretching apparatus including a rail support device installed in the clip chain type sheet stretching apparatus configured to hold an end portion in a transverse direction of a sheet by using clips of clip chains, and to stretch the sheet while conveying the sheet by running the clip chains in a horizontal direction along a rail, the rail support device configured to support the rail and including:
• a first rail support member configured to support a first straight portion of the rail;
• a second rail support member configured to support a second straight portion of the rail in a direction intersecting the first straight portion;
• and an arc shaped rail support member configured to support an arc shaped portion of the rail connecting the first and second straight portions to each other, wherein the first rail support member includes a first connecting portion and a first straight rail support portion being a portion other than the first connecting portion, the second rail support member includes a second connecting portion and a second straight rail support portion being a portion other than the second connecting portion, the first connecting portion and the second connecting portion are engaged with each other, the second rail support is rotatable relative to the first rail support member about a first axis extending in a vertical direction at the first and second connecting portions, the first and second rail support members respectively support the first and second straight portions by the first and second straight rail support portions with longitudinal directions of the first and second rail support members respectively set to coincide with longitudinal directions of the first and second straight portions, the arc shaped rail support member is engaged with at least one of the first connecting portion and the second connecting portion to form a higher pair so as to rotate relative to the at least one connection portion about the first axis and to move relative to the at least one connection portion along a first straight line passing through the first axis and extending in the horizontal direction, the arc shaped rail support member is engaged with the first connecting portion to form a higher pair so as to rotate relative to the first connecting portion about a second axis extending in the vertical direction at the first connecting portion and to move relative to the first connecting portion along a second straight line passing through the second axis and extending in the horizontal direction, the arc shaped rail support member is engaged with the second connecting portion to form a higher pair so as to rotate relative to the second connecting portion about a third axis extending in the vertical direction at the second connecting portion and to move relative to the second connecting portion along a third straight line passing through the third axis and extending in the horizontal direction, the first axis exists in an intersection angle bisecting plane developing in the vertical direction and including an intersection angle bisector being a straight line passing through an intersection point between an extended line of the first straight portion and an extended line of the second straight line and extending in the horizontal direction while bisecting an intersection angle of the extended lines of the first and second straight portions, the arc shaped rail support member supports the arc shaped portion of the rail in the intersection angle bisecting plane, the first straight line extends in a direction of extension of the intersection angle bisector, the first rail support member and the second rail support member are symmetrical to each other with respect to the intersection angle bisecting plane, the second straight line extends in the horizontal direction intersecting with the intersection angle bisecting plane, and the third straight line and the second straight line are symmetrical to each other with respect to the intersection angle bisecting plane;
• and
• stretching the sheet using the clip chain type sheet stretching apparatus.