US 4,825,787 AGranted

Method and apparatus for guiding fabric to a sewing machine

AssigneePorter Sewing Machines, Inc.

InventorsEdward Babson, Thomas G. Brophy, Steven Marcangelo

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Abstract

Method and apparatus for aligning fabric as it is advanced in a prescribed direction toward a sewing machine such as a double overlock seamer for stitching pants. Photosensitive devices sense displacement of edges of upper and lower fabric plies relative to a desired alignment line. Error signals are produced when either ply edge is displaced from the desired alignment line. Friction wheels responsive to the respective error signals guide each ply toward the desired alignment line as it is advanced toward the sewing machine. Each friction wheel pivots about an axis perpendicular to the ply and is controlled by a stepper motor. Each friction wheel is movable between an operating position in which it is biased against the respective fabric ply, and a retracted position for insertion or removal of fabric. The pressure applied to the fabric ply by the friction wheel is adjustable. A centering device aligns each friction wheel with the direction of fabric movement toward the sewing machine when no fabric is present in the apparatus.

Claims27

Dependent claims

Apparatus for aligning an upper ply and a lower ply moving in a prescribed direction prior to stitching in a sewing machine, said apparatus comprising:

upper sensing means for sensing displacement in a direction lateral to the prescribed direction of movement of an edge of the upper ply relative to a desired upper alignment line;
upper feedback means responsive to said upper sensing means for providing an upper error signal when said upper ply edge is displaced from said desired upper alignment line;
upper ply guide means responsive to said upper error signal for guiding said upper ply toward said desired upper alignment line as it is advanced toward the sewing machine, said upper ply guide mans comprising an upper friction wheel that rotates about a wheel axis parallel to the upper ply and that is continuously in contact with the upper ply during alignment, said upper friction wheel being normally aligned with the direction of upper ply movement and being pivoted to the left or right about a pivot axis that is perpendicular to the upper ply and intersects the wheel axis of said upper friction wheel, when said upper error signal indicates that the upper ply is displaced from the upper alignment line;
lower sensing means for sensing displacement in the direction lateral to the prescribed direction of movement of an edge of the lower ply relative to a desired lower alignment line;
lower feedback means responsive to said lower sensing means for providing a lower error signal when said lower ply edge is displaced from said desired lower alignment line;
and
lower ply guide means responsive to said lower error signal for guiding said lower ply toward said desired lower alignment line as it is advanced toward the sewing machine, said lower ply guide means comprising a lower friction wheel that rotates about a wheel axis parallel to the lower ply and that is continuously in contact with the lower ply during alignment, said lower friction wheel being normally aligned with the direction of lower ply movement and being pivoted to the left or right about a pivot axis that is perpendicular to the lower ply and intersects the wheel axis of said lower friction wheel, when said lower error signal indicates that the lower ply is displaced from the lower alignment line.

4 more elements

Apparatus for use with a sewing machine wherein a ply is moved in a prescribed direction toward the sewing machine, said apparatus comprising:

sensing means for sensing displacement in a direction lateral to the prescribed direction of movement of an edge of the ply relative to a desired alignment line;
feedback means responsive to said sensing means for providing an error signal when said ply edge is displaced from said desired alignment line;
and
ply guide means responsive to said error signal for guiding said ply toward said desired alignment line as it is advanced toward the sewing machine, said ply guide means comprising a friction wheel that rotates about a wheel axis parallel to the ply and that is continuously in contact with the ply during alignment, said friction wheel being normally aligned with the direction of ply movement and being pivoted to the left or right about an axis that is perpendicular to the ply and intersects the wheel axis of said friction wheel, when said error signal indicates that the ply is displaced from the alignment line.

1 more element

A method for aligning an upper ply and a lower ply moving in a prescribed direction prior to stitching in a sewing machine, said method comprising the steps of:

sensing displacement of an edge of the upper ply relative to a desired upper alignment line and providing an upper error signal when said upper ply edge is displaced from said desired upper alignment line;
guiding said upper ply edge toward said desired upper alignment line in response to said upper error signal by biasing an upper friction wheel continuously against the upper ply during alignment and pivoting the upper friction wheel to the left or right of a normal position aligned with the direction of upper ply movement, said upper friction wheel being pivoted about an axis that is perpendicular to said upper ply and intersects the wheel axis of said friction wheel;
sensing displacement of an edge of the lower ply relative to a desired lower alignment line and providing a lower error signal when said lower ply edge is displaced from said desired lower alignment line;
and
guiding said lower ply edge toward said desired lower alignment line in response to said lower error signal by biasing a lower friction wheel continuously against the lower ply during alignment and pivoting the lower friction wheel to the left or right of a normal position aligned with the direction of lower ply movement, said lower friction wheel being pivoted about an axis that is perpendicular to said lower ply and intersects the wheel axis of said friction wheel.

2 more elements

Dependencies are inferred from the claim text.