Abstract: An invisible zipper with a rectangular positioning unit includes two strips, teeth, a slide and a rectangular positioning unit. The two strips are sewed to an opening. The teeth are disposed along each strip. The slide is disposed on one of the strips and can slide along the two strips. The rectangular positioning unit is fixedly disposed at the end of one of the two strips. In use, the end of the other strip is inserted through the slide and into the rectangular positioning unit. Now, we can use the slide to bring together the two strips or separate them.

Abstract: String core-free invisible zipper structure including a pair of zipper belts and zipper teeth windingly extended and continuously lengthwise sewn along the inward folded edge of each zipper belt. Each zipper tooth has an upper and a lower leg sections and a head section. The gap between the upper and lower leg sections of the zipper tooth is gradually converged from the head section of the zipper tooth to the heels of the upper and lower leg sections, whereby the extensible tolerance of the connecting section between the upper and lower leg sections of adjacent zipper teeth is reduced and the deformation of the zipper teeth caused by lateral pull is reduced. Therefore, the zipper teeth have sufficient buckling strength and the possibility of disengagement of the zipper teeth is minimized. Therefore, the string core passing through the zipper teeth is no more necessary for reinforcing the anti-pull strength of the zipper teeth.

Abstract: String core-free invisible zipper structure including a pair of zipper belts and zipper teeth windingly extended and continuously lengthwise sewn along the inward folded edge of each zipper belt. Each zipper tooth has an upper and a lower leg sections and a head section. The gap between the upper and lower leg sections of the zipper tooth is gradually converged from the head section of the zipper tooth to the heels of the upper and lower leg sections, whereby the extensible tolerance of the connecting section between the upper and lower leg sections of adjacent zipper teeth is reduced and the deformation of the zipper teeth caused by lateral pull is reduced. Therefore, the zipper teeth have sufficient buckling strength and the possibility of disengagement of the zipper teeth is minimized. Therefore, the string core passing through the zipper teeth is no more necessary for reinforcing the anti-pull strength of the zipper teeth.

Abstract: Method and device for manufacturing string core-free invisible zipper. Without string core, the molded zipper racks are separately and directly loosely reversely fed into the needle seat of the machine. The fabric belts are at the same time fed into the needle seat for sewing the zipper racks thereon. Prior to feeding the racks into the needle seat, it is not necessary to use a rack separating bar to forcedly stretch open the two racks. Accordingly, the zipper racks are prevented from being tensioned and deformed or curled and the pitch will be unified. The slider can more smoothly slide without being obstructed. The teeth of the racks can more firmly mesh with each other.

Abstract: Method and device for manufacturing string core-free invisible zipper. Without string core, the molded zipper racks are separately and directly loosely reversely fed into the needle seat of the machine. The fabric belts are at the same time fed into the needle seat for sewing the zipper racks thereon. Prior to feeding the racks into the needle seat, it is no more necessary to use a rack separating bar to forcedly stretch open the two racks. Accordingly, the zipper racks are prevented from being tensioned and deformed or curled and the pitch will be unified. The slider can be more smoothly slided without being obstructed. The teeth of the racks can more firmly mesh with each other.