Thread pull-off and wiping mechanism for sewing machines

Claim 2

In a sewing machine having an endwise reciprocating thread carrying needle, a needle thread take-up mechanism, and a circularly moving actuator for said needle and take-up mechanism, a needle thread manipulating mechanism comprising thread-engaging means shiftably supported on said sewing machine for movement between two extreme positions, spring means biasing said threadengaging means toward a first extreme position, a linkage carried on said sewing machine and operatively connected to said threadengaging means, cam means driven by said circularly moving actuator and engageable with said linkage to drive said threadengaging means into a second extreme position, and selectively releasable latch means for detaining said linkage out of engagement with said cam means.

Claim 3

A needle thread manipulating mechanism as set forth in claim 1 in which said thread-engaging means includes a thread pull-off element and a thread wiping element each shiftably supported on said sewing machine and operated in concert by said linkage, and in which said elements are arranged each to traverse a different segment of the regular needle thread path when moving from one extreme position to another.

Claim 4

A needle thread pull-off and wiping mechanism as set forth in claim 2 in which said thread pull-off element engages and draws needle thread from said regular needle thread path when driven by said cam means into said second extreme position, and in which said thread wiping element engages and draws needle thread from said regular needle thread path when returned by said spring means into said first extreme position.

Claim 5

A needle thread manipulating mechanism as set forth in claim 1 in which said selectively releasable latch means is operated by an electric solenoid so that the operation of the thread manipulating mechanism is initiated by an electric signal to said solenoid but driven mechanically by said cam means.

Claim 6

A needle thread manipulating mechanism as set forth in claim 1 in which said cam means is constrained for movement in a predetermined path in response to said circularly moving actuator and cooperates with a link which is pivotally connected to said linkage, which link extends substantially parallel to the predetermined path of movement of cam means, means defining a cam engaging surface on said link which extends substantially perpendicular to the predetermined path of said cam means so that said link will be shifted substantially endwise by said cam means to drive said thread-engaging means, and in which said selectively releasable latch means detains the cam engaging surface on said link beyond the path of said cam means.

Claim 7

A needle thread manipulating mechanism as set forth in claim 5 in which the means for biasing the thread-engaging means toward a first extreme position comprises a single spring which also biases said link into the path of the cam means when the latch means is released, said single spring being arranged to act between said sewing machine frame and said link for applying two components of spring force to said link, one component acting in a direction passing through said pivotal connection of said link with said linkage for biasing said thread-engaging means toward a first extreme position and the other component acting perpendicularly thereto for biasing the cam engaging surface of the link into the path of the cam means.

Claim 8

A needle thread manipulating mechanism as set forth in claim 6 in which said selectively releasable latch means comPrises a retractable latch pin axially shiftably supported on said sewing machine frame for movement transversely of said link into an extended position across a latch cooperating edge of said link and a retracted position out of engagement with said link, said latch pin when in said extended position being effective to detain said link radially out of the path of said cam means, in which in the spring biased first position of said thread-engaging means the link when released by retraction of the latch pin moves into a blocking position in front of the latch pin, and in which the latch cooperating edge of the link extends at such an inclination of the length direction of said link that the link will shift out of the blocking position in front of the latch pin when said linkage is driven into said second extreme position.

Claim 9

A needle thread manipulating mechanism as set forth in claim 7 in which an electrical solenoid is provided for shifting the latch pin into a retracted position, and spring means is provided for returning the latch pin to extended position.