Accordion-sides square-bottom bag and manufacturing method thereof
View Patent ↗An accordion-sides square-bottom bag and manufacturing method thereof, comprising a paper tube ( 10 ) made by a sheet enclosing the sides; accordion sides are folded on two sides of the paper tube ( 10 ); the paper tube is provided with a first indentation line ( 21 ) and a second indentation line ( 22 ), the distance from the second indentation line ( 22 ) to the base being greater than the distance between the first indentation line and the second indentation line, but not exceeding twice the distance; two ends of the second indentation line ( 22 ) are symmetrically provided with a first crease line ( 31 ) and a second crease line ( 32 ), the distances between the respective ends of the first and second crease lines and the two edges of the paper tube ( 10 ) exceeding the folded depth of the accordion sides; and a first cutting line ( 41 ) and a second cutting line ( 42 ) are provided from the ends of the first and second crease lines to the base of the paper tube ( 10 ). The accordion-sides square-bottom bag enlarges the area of the glued surface of the bottom of the bag, such that the material on the bottom is uniformly distributed, and the bottom is adhered firmly, thus reducing the maximum thickness of the bottom, and reducing the footprint of packaged material during transportation.
1. A method of manufacturing the accordion-sides square-bottom bag; the accordion-sides square-bottom bag is constituted by a paper cylinder formed by sealing two edges of a sheet of paper material; two sides of the paper cylinder are formed with two accordion folds respectively; a first indentation line and a second indentation line parallel to a bottom edge of the paper cylinder are formed on the paper cylinder; a distance between the second indentation line and the bottom edge of the paper cylinder is greater than a distance between the first indentation line and the second indentation line, but does not exceed twice the distance between the first indentation line and the second indentation line; a first crease line and a second crease line are symmetrically provided respectively at two respective ends of the second indentation line; the first crease line and the second crease line do not touch the bottom edge of the paper cylinder; two distances from ending points of the first crease line and the second crease line to their respective proximate sides of the two sides of the paper cylinder are respectively greater than respective folding depths of the accordion folds at the two sides of the paper cylinder; the ending points of the first crease line and the second crease line are joined with one end of a first cutting line and one end of a second cutting line respectively; another end of the first cutting line and another end of the second cutting line contact the bottom edge of the paper cylinder;
wherein the method comprises the following steps:
step 1: sealing the two edges of the sheet of paper material to form the paper cylinder; forming accordion crease lines for the accordion folds on the paper cylinder by punching or rolling; forming the accordion folds to form the paper cylinder which has the accordion folds;
step 2: after step 1 and before step 3, forming the first indentation line and the second indentation line on the paper cylinder having the accordion folds by punching;
step 3: after step 2 and prior to flipping a front surface of the paper cylinder upward from the bottom edge of the paper cylinder and folding the front surface upward along the first indentation line, forming the first crease line and the second crease line symmetrically by pressing, with their starting points begin at two respective ends of the second indentation line; wherein the first crease line and the second crease line form two angles of 45 degrees with respect to the two sides of the paper cylinder respectively;
step 4: joining the ending points of the first crease line and the second crease line with one end of the first cutting line and one end of the second cutting line respectively, while another end of the first cutting line and another end of the second cutting line contact the bottom edge of the paper cylinder, and wherein cutting performed along the first cutting line enables two surfaces of the paper cylinder to be cut simultaneously, and cutting performed along the second cutting line also enables the two surfaces of the paper cylinder to be cut simultaneously.
2. The method according to claim 1 , wherein the first cutting line, the second cutting line, the first crease line and the second crease line are complete lines.