Packaging case and method for assembling the packaging case

Abstract

A packaging case includes a rectangular bottom plate, a pair of first lateral plates, a second lateral plate, a top plate, and a pair of third lateral plates. The pair of first lateral plates is connected, each via a first crease line, to two opposed sides of the bottom plate and each has an L-shaped first engagement groove. The pair of third lateral plates is connected, each via a fourth crease line, to two sides of the top plate parallel to the first lateral plates and each has an L-shaped second engagement groove bent oppositely to a bending direction of the first engagement groove in a state where the third lateral plates overlap the first lateral plates. When the second engagement groove is engaged with the first engagement groove, the first lateral plates and the third lateral plates are connected while alternately intersecting each other in thickness directions thereof.

What is claimed is: 
     
         1 . A packaging case assembled by folding a sheet, the packaging case comprising:
 a rectangular bottom plate;   a pair of first lateral plates that is connected, each via a first crease line, to two opposed sides of the bottom plate and becomes upright with respect to the bottom plate in an assembled state;   a second lateral plate that is connected, via a second crease line, to another side of the bottom plate adjacent to the pair of first lateral plates and becomes upright with respect to the bottom plate in the assembled state;   a top plate that is connected, via a third crease line, to a side of the second lateral plate opposed to the bottom plate and becomes opposed to the bottom plate in the assembled state; and   a pair of third lateral plates that is connected, each via a fourth crease line, to two sides of the top plate parallel to the pair of first lateral plates and overlaps the pair of first lateral plates in the assembled state,   wherein each of the pair of first lateral plates has an L-shaped first engagement groove extending from an end edge thereof opposed to the first crease line toward the first crease line and bent toward the second lateral plate,   each of the pair of third lateral plates has an L-shaped second engagement groove extending from an end edge thereof opposed to the fourth crease line toward the fourth crease line and bent in a direction opposite to a bending direction of the first engagement groove in a state where the pair of third lateral plates overlaps the pair of first lateral plates, and when the second engagement groove is engaged with the first engagement groove,   the pair of first lateral plates and the pair of third lateral plates are connected while alternately intersecting each other in thickness directions thereof.   
     
     
         2 . The packaging case according to  claim 1 , wherein
 inner corners of respective bent parts of the first engagement groove and the second engagement groove are diagonally cut out.   
     
     
         3 . The packaging case according to  claim 1 , wherein
 the first engagement groove is tapered at an end near an opening thereof so as to have a groove width increasing toward the opening as viewed from the thickness direction of the pair of first lateral plates.   
     
     
         4 . A method for assembling a packaging case, the packaging case being assembled by folding a sheet and comprising:
 a rectangular bottom plate;   a pair of first lateral plates that is connected, each via a first crease line, to two opposed sides of the bottom plate and becomes upright with respect to the bottom plate in an assembled state;   a second lateral plate that is connected, via a second crease line, to another side of the bottom plate adjacent to the pair of first lateral plates and becomes upright with respect to the bottom plate in the assembled state;   a top plate that is connected, via a third crease line, to a side of the second lateral plate opposed to the bottom plate and becomes opposed to the bottom plate in the assembled state; and   a pair of third lateral plates that is connected, each via a fourth crease line, to two sides of the top plate parallel to the pair of first lateral plates and overlaps the pair of first lateral plates in the assembled state,   wherein each of the pair of first lateral plates has an L-shaped first engagement groove extending from an end edge thereof opposed to the first crease line toward the first crease line and bent toward the second lateral plate, and   each of the pair of third lateral plates has an L-shaped second engagement groove extending from an end edge thereof opposed to the fourth crease line toward the fourth crease line and bent in a direction opposite to a bending direction of the first engagement groove in a state where the pair of third lateral plates overlaps the pair of first lateral plates, the method comprising steps of:   valley-folding each of the pair of first lateral plates along the first crease line so that the each of the pair of first lateral plates becomes upright with respect to the bottom plate;   valley-folding each of the pair of third lateral plates along the fourth crease line so that the each of the pair of third lateral plates becomes upright with respect to the top plate and valley-folding the second lateral plate and the top plate along the second crease line and the third crease line, respectively, so that the top plate becomes opposed to the bottom plate;   bringing the second engagement groove into engagement with the first engagement groove so that each of the pair of third lateral plates and a corresponding one of the pair of first lateral plates alternately intersect each other in thickness directions thereof; and   sliding the top plate and the pair of third lateral plates in a direction toward the second lateral plate so that the first engagement groove and the second engagement groove are fitted into each other up to respective L-shaped bent parts thereof.