Automatic bobbin rewinding for sewing machines

A bobbin rewinding mechanism comprising

• a. a rewind shaft having an exposed end adapted to receive a bobbin,
• b. means forming a support surface for said bobbin for axially positioning the bobbins during rewind operations,
• c. a controllable first magnetic member positioned behind said surface and operative to attract said bobbin toward the rewind position, and
• d. second magnetic means for engaging and removing said bobbin from said rewind position.

The method of effecting bobbin exchange and refilling on a continuous basis, which comprises

• a. rewinding an empty bobbin in a rewind station,
• b. combining the rewound bobbin with its case at the rewind station and engaging a used bobbin and bobbin case for removal from the sewing position,
• c. simultaneously rotating the respective bobbin and bobbin case assemblies 180.degree. about an axis midway between them,
• d. maintaining the thread attached to the rewound bobbin throughout at least a substantial portion of said 180.degree. rotation,
• e. clamping the thread leading to said rewound bobbin and then severing the thread between the bobbin and the point at which the thread is clamped,
• f. positioning the used bobbin in the rewind station, and
• g. commencing a further bobbin rewind operation by rotating the used bobbin while pressing the clamped thread section against the side of the rotating bobbin,
• h. the bobbin having an edge opening slot in its end wall for engaging the pressed thread.

A system for rewinding and reloading a bobbin in a sewing machine, which comprises

• a. a source of thread under tension,
• b. means for rotatably supporting a bobbin spool for rewinding,
• c. means for applying to the rewound spool an open end bobbin case,
• d. said bobbin case having an edge opening slot and a tension spring overlying the closed end of the slot,
• e. said means for applying being operative to orient said bobbin case such that the tensioned thread leading from said source enters said slot,
• f. a thread engaging lug mounted for movement along the outside of said bobbin case, in the area of said slot and operative to force the tensioned thread toward the closed end of said slot and under said tension spring.

A bobbin and bobbin case assembly for use in an automatic bobbin rewinding and exchange system, which comprises

• a. a bobbin case having an open end and a closed end and a cylindrical side wall,
• b. said bobbin case being formed with an access opening in one of its walls for the reception of a magnetic retainer, and
• c. a bobbin formed at least in part of magnetic material,
• d. said bobbin and bobbin case being so constructed and arranged that a magnetic part of said bobbin is disposed adjacent said access opening when said bobbin and bobbin case are assembled.

A bobbin rewinding system for a sewing machine, which comprises

• a. a bobbin rewinding shaft and means for effecting controllable rotation thereof,
• b. a bobbin spool adapted for reception on said shaft,
• c. said bobbin spool having one end wall formed with an edge opening slot for the reception of a thread,
• d. a source of thread under controlled tension,
• e. means for guiding said thread adjacent to but out of contact with the slotted side wall of said bobbin spool, and
• f. movable thread guide means operable to displace said guided thread into contact with said slotted side wall while said bobbin is being rotated, whereby said thread is engaged by and wound upon said bobbin.

A bobbin rewinding and exchange system for use in connection with a sewing machine, comprising

• a. a transfer arm assembly for simultaneously engaging a pair of bobbins and exchanging them between sewing and rewinding positions,
• b. a shaft mounting said transfer arm assembly for unidirectional rotation in 180.degree. increments and for axial movement between retracted and advanced positions,
• c. first clutch-like means engaging said transfer arm assembly to said shaft when said assembly is in a retracted position,
• d. second clutch-like means for retaining said transfer arm assembly in a fixed rotational orientation when said assembly is in an advanced position,
• e. means for effecting rotation of said shaft in a forward direction when said transfer arm assembly is in a retracted position, and
• f. means for effecting rotation of said shaft in a reverse direction when said transfer arm assembly is in an advanced position.