Sewing – Stitch forming – Feeding work material
Patent
1989-12-28
1991-03-12
Schroeder, Werner H.
Sewing
Stitch forming
Feeding work material
11212113, 112154, 112148, 112235, 112450, D05B 2700, D05B 4700, D05B 3508, D05B 4700
Patent
active
049984926
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject of this invention is a method and apparatus to reduce puckering in machine sewn seams.
It is known to form on a work piece a line of machine stitching substantially free from puckering by placing a stitch-engaging element of a width less than the length of a stitch to project across the line of stitching in advance of the sewing position, allowing the element to remain in position across the line of stitching until a stitch has been formed overlying the element then withdrawing the element from below the formed stitch.
All the known apparatus intended to reduce or eliminate puckering has incorporated a stitch-engaging element in the form of a rigid finger operatively connected to the sewing machine mechanism and synchronized therewith to move transversely across the line of stitching immediately before each stitch is formed and then to be withdrawn from below the formed stitch immediately after the stitch is formed.
Such known apparatus has either to be built into the machine during manufacture of the machine or if it is to be fitted to an existing machine extensive modification of the machine is required to adapt it to receive the stitch-engaging element and its operating mechanism.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a simple method of and apparatus for reducing puckering in seams which can be readily fitted to any existing sewing machine and which does not normally require to be linked in any way with the machine mechanism.
According to the invention apparatus for forming on a work piece a line of stitching substantially free from puckering by placing a stitch-engaging element of a width less than the length of a stitch to project across the line of stitching at the sewing position is characterized by employing as the stitch-engaging element a number of flexible filamentary elements arranged side by side in close juxtaposition as an endless row of stitch-engaging elements movable in a direction longitudinally of the row of stitch-engaging elements and positioned so that a portion of the row of stitch-engaging elements projects permanently across the line of stitching at the sewing position.
The apparatus defined above may include a disc presenting flexible filamentary elements projecting radially from the periphery of the disc completely around the periphery of the disc to form an endless row of stitch-engaging elements, said disc being rotatable about an axis arranged to be located to one side of the line of stitching adjacent to the sewing position such that at least one element constituting a portion of said endless row always projects across the line of stitching at the sewing position.
The portion of the row of stitch-engaging elements projecting permanently across the line of stitching may comprise several stitching elements covering a portion of the line of stitching from a point in advance of the needle of a sewing machine to a point at the rear of the needle.
The disc may be flat or dished.
Alternatively the apparatus may be constituted by a wheel having a coned rim from the larger diameter end of which flexible stitch-engaging elements disposed around the periphery of the rim project, the elements being orientated to lie on the surface of an imaginary right cone the axis of which is coincident with the axis of the wheel, the wheel being rotatable about an axis inclined with respect to the surface on which the work to be stitched lies during stitching, the angle of inclination of said axis being such that there is always at least one stitch-engaging element adjacent the work surface and projecting across the line of stitching to be formed in advance of the needle position.
The stitch-engaging elements may be attached to an endless band wrapping two spaced freely rotatable pulleys. Alternatively the stitch-engaging elements may be attached to a free endless band guided to traverse the sewing position.
The flexible filamentary elements may be filaments of a synthetic material such as nyl
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Aitken John
Fletcher John
Izaguirre Ismael
J. & P. Coats Limited
Schroeder Werner H.
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