Method and apparatus for sewing book blocks without blind stitch by means of hooks

A bookbinding sewing machine for sewing signatures into book blocks comprises:

• one or more spools for providing corresponding sewing threads.
• one or more needles and one or more crochets for forming corresponding one or more stitchings between the signatures of each of the book blocks with the sewing threads, wherein the stitchings comprise one or more rows of plain stitches formed by the needles and one or more rows of looped stitches formed by the crochets being concatenated to each other, the rows of looped stitches ending with corresponding free loops on a last one of the signatures of the book block,
• means for bringing the sewing threads, upstream of the corresponding plain stitches along corresponding feeding directions of the sewing threads;
• from the corresponding spools, each to a catching position being aligned with a corresponding one of the free loops formed by the sewing thread along an advancement line of the signatures during the sewing thereof, means for bringing the sewing threads each from the catching position to a concatenation position by passing the sewing thread through the corresponding free loop along the advancement line,
• corresponding one or more hooks for bringing the sewing threads each from the concatenation position to a closure position away from the corresponding free loop thereby tightening the free loop around the sewing thread being passed therethrough, the sewing thread being free to slide relative to the corresponding hook during said bringing the sewing thread from the concatenation position to the closure position, and
• means for cutting the sewing threads each upstream of a portion thereof being tightened by the corresponding free loop along the feeding direction, the means for cutting being configured for cutting the sewing threads after said bringing the sewing threads each from the concatenation position to the closure position.