Automatic trouser indexing method and apparatus for belt loop attachment with improved tension control and seam detection

A method of stitching belt loops onto the waistband of trousers comprising,

• determining the number of loops to be stitched onto the waistband,
• setting a number of indexed stops to be made based on the determined number of loops to be stitched,
• placing an end of the waistband corresponding to where a first waistband loop is to be attached onto the stitching station of a sewing machine,
• stitching a first belt loop at the first belt loop attachment position,
• indexing the trousers lengthwise while detecting a waistband seam,
• correlating subsequent belt loop attachment positions with a position of a detected seam in accordance with the number of indexed stops, and.
• incrementally indexing the trousers lengthwise while detecting seams, and stopping the lengthwise indexing of the trousers when seams are detected at belt loop attachment positions while stitching a belt loop at each belt loop attachment position.

An apparatus for indexing the waistband of trousers into belt loop attachment positions on a sewing machine bed at a stitching station of a sewing machine, comprising

• means for moving the waistband of trousers lengthwise through the stitching station,
• means for detecting the presence of a seam while the waistband is moving,
• means for correlating the waistband attachment positions for belt loops relative to the detected position of the seam,
• means for controlling the movement of the waistband through the stitching station for incrementally positioning the belt loop attachment positions at the stitching station for stitching of belt loops onto the waistband, and
• an edge folder positioned adjacent to the sewing machine bed,
• means for moving the edge folder downward against a waistband portion that extends past the sewing machine bed for folding over the waistband, and
• means for clamping a folded-over waistband portion and exerting tension thereon.

An apparatus for stitching belt loops onto the waistband of trousers comprising,

• a sewing machine having a sewing machine arm defining a stitching station where belt loops are stitched onto the waistband of trousers,
• an indexer clamp that engages the trousers,
• a stepper motor drivingly connected to said indexer clamp for driving said clamp and moving the waistband of an engaged pair of trousers in one direction lengthwise through the stitching station,
• seam detector means for detecting a seam as the waistband is moved through the stitching station, and
• control means operatively connected to said seam detector means and said stepper motor for 1) receiving signals from said seam detector means indicative of the presence of a seam, 2) correlating the detected position of the seam with the attachment position of belt loops, and 3) controlling the stepper motor to stop when each of successive belt loop attachment positions are moved at the stitching station, and
• a frame. a first lever arm pivotally mounted on said frame, and a roller mounted on the first lever arm so that the roller engages the waistband, wherein said first lever arm pivots when engaging a seam, and
• signal generating means operatively connected to said control means and said first lever arm and responsive to said pivoting action of said first lever arm for generating a signal to said control means indicative of the presence of a seam.