Method and apparatus for sewing mitered corners on a split needle bar sewing machine

A semi-automatic split needle bar sewing machine having multiple needles, a presser foot and a motor for sewing mitered corners in decorative and functional stitching on sewn products, comprising:

• means for disengaging one of the needles of the split bar needle to discontinue double needle sewing on the inside seam at the inside corner of the mitered corner and allow only single needle sewing on the outside seam;
• means for varying the length of stitches being sewn;
• means for counting the number of stitches being sewn;
• means for raising and lowering the pressure foot;
• means for braking the motor and positioning the needle;
• means for storing a profile for a plurality of mitered corners to define the relative position of the inside corner and the apex point of each mitered corner;
• calculating means for calculating the length and number of stitches to be sewn in the outside seam of he mitered corner between the disengagement point at the inside corner and the apex of the mitered corner;
• means for controlling the operation of the sewing machine to sew a mitered corner according to a selected one of said profiles by discontinuing double needle sewing at the inside corner of the mitered corner through control of said needle disengaging means and single needle sewing a number of stitches on the outside seam defined by said calculation means between the disengagement point and the apex on one side of the mitered corner and a number of stitches equal to the calculated number on said one side between the apex and the inside corner on the other side of the mitered corner with the stitch length varied to achieve the correct mitered corner in accordance with said calculation means;
• said controlling means automatically braking the motor and positioning one of the needles down with the presser foot elevated at the apex of the corner;
• and
• said controlling means automatically re-engaging the remaining needle at the inside corner on the other side of the mitered corner.

A method for sewing mitered corners on a split needle bar sewing machine, comprising:

• automatically terminating double needle sewing by disengaging the inside needle at the inside corner of the mitered corner and allowing only single needle sewing on the outside seam;
• calculating the length and number of stitches to be sewn on the outside seam between the disengagement point at the inside corner and the apex;
• sewing the calculated number of stitches on the ouside seam to the apex of the mitered corner;
• varying the length of the stitches in accordance with the calculated stitch length;
• automatically terminating single needle sewing at the apex and allowing realignment of the material to sew the remaining side of the mitered corner;
• sewing the calculated number of stitches upon resumption of single needle sewing to sew an identical number of stitches on the outside seam on the opposite side of the mitered corner from the apex to the point corresponding to the inside corner;
• varying the length of the stitches in accordance with the calculated stitch length;
• and
• automatically resuming double needle sewing by reengaging the inside needle when the calculated number of stitches on the outside seam has been sewn.

A method for sewing mitered corners on a split needle bar sewing machine for decorative and functional stitching of apparel products, comprising:

• storing a profile containing the parameters of a desired mitered corner to be sewn with respect to the dimensions of the outside seam relative to the inside seam;
• determining the relative position of the inside corner of the mitered corner with respect to the material edge;
• automatically terminating double needle sewing at the inside corner by disengaging the inside needle and allowing only single needle sewing on the outside seam thereafter;
• calculating the number of stitches and the length thereof for the outside seam between the disengagement point at the inside corner and the apex;
• counting the number of stitches being sewn between the inside corner and the apex of the mitered corner on one side thereof;
• varying the length of at least one of the stitches being sewn such that the overall length of the stitches is equal to the calculated value;
• terminating single needle sewing at the apex and raising and lowering the presser foot to allow manual realignment of the material when the presser foot is raised;
• counting the number of stitches sewn between the apex of the mitered corner and the inside corner on the other side of the mitered corner during single needle sewing from the apex to the inside corner;
• varying the length of at least one of the stitches being sewn on the outside seam between the apex and the point at which the inside needle is proximate the inside corner on the other side of the mitered corner such that the outside needle is in the down position when the inside needle is proximate the inside corner wherein the correct mitered corner is achieved;
• and
• automatically resuming double needle sewing at the inside corner by reengaging the inside needle.

A method for sewing mitered corners on a split needle bar sewing machine for decorative and functional stitching of sewn products, comprising:

• individually inputting the parameters of the mitered corner on a keyboard for a desired mitered corner having a specified angle, needle gauge and stitch density between the seams;
• determining the relative position of the inside corner of the mitered corner with respect to the material edge;
• automatically terminating double needle sewing at the inside corner and allowing only single needle sewing thereafter;
• counting the number of stitches being sewn between the inside corner and the apex of the mitered corner on one side thereof;
• varying the length of at least one of the stitches being sewn such that that correct mitered corner is achieved;
• terminating single needle sewing at the apex and raising and lowering the presser foot to allow manual realignment of the material;
• counting the number of stitches sewn between the apex of the mitered corner and the inside corner on the other side of the mitered corner during single needle sewing from the apex to the inside corner;
• varying the length of at least one of the stitches being sewn between the apex and the inside corner of the mitered corner on the other side thereof such that the correct mitered corner is achieved;
• and
• automatically resuming double needle sewing at the inside corner.

A method for sewing mitered corners on a split needle bar sewing machine for decorative and functional stitching on sewn products, comprising:

• inputting and storing parameters defining a profile for a desired mitered corner having an inside corner along the inner seam thereof and an apex on the outer seam thereof, the gauge of the needles, and the stitch density;
• detecting the presence of a discontinuity on the material from the feeding side of the presser foot of the sewing machine to provide a reference point between the needle and the material;
• determining the position of the inside corner with respect to the detected discontinuity according to the predetermined profile;
• counting a predetermined number of stitches to the inside corner determined from a reference point stored in the predetermined profile, the last stitch of which is varied;
• terminating double needle sewing at the inside corner by disabling the inner needle;
• calculating the number of whole stitches having a length determined by the stored stitch density required to sew the seam from the disengagement point to the apex and the length of the last stitch such that the needle is in the down position at the apex;
• counting the calculated number of whole stitches between the disengagement point and the apex of the mitered corner during single needle sewing on one side of the mitered corner and varying the length of the last stitch in accordance with the calculated length such that the correct mitered corner is achieved;
• terminating single needle sewing at the apex of the mitered corner and raising and lowering the presser foot to allow manual realignment of the material for resuming single needle sewing;
• counting a predetermined number of stitches between the apex and the point at which the inside needle is proximate the inside corner during single needle sewing on the other side of the mitered corner, the first stitch of which has the length thereof varied to equal the length of the last stitch on the first side and the remaining stitches sewn at full length such that and correct mitered corner is achieved;
• and
• resuming double needle sewing by enabling the inside needle at the pivot point to end the pattern of the mitered corner.