Apparatus and method for detecting broken hooks of needles in a knitting machine, and needles for use with same

An apparatus for detecting broken hooks of needles in a knitting machine having first and second cam faces defining a cam for slidably receiving needle butts, the cam comprising a raising cam portion for moving the needles to a raised position for receiving yarns, a stitch cam portion following the raising cam portion for moving the needles to a stitch position for making yarn loops, and a welt cam portion following the stitch cam portion in which tension forces between the yam loops and needle hooks bias the butts of intact needles against the first cam face, the apparatus comprising:

• a detector butt raising segment in the welt cam portion, wherein the second cam face in the welt cam portion is inclined away from the second cam face at the stitch position for contacting butts and urging the butts toward the first cam face;
• a detector butt lowering segment in the welt cam portion following the detector butt raising segment, wherein the first cam face contacts the needle butts and urges the butts toward the second cam face;
• a detector recess segment in the welt cam portion following the detector butt lowering segment, wherein the second cam face is sufficiently spaced from the first cam face so that butts of needles having broken hooks are urged into the recess segment by the detector butt lowering segment, but butts of intact needles that are biased against the first cam face do not enter the detector recess segment;
• and
• a sensor for identifying needles having needle butts in the detector recess segment,
• wherein the sensor is positioned outside of the detector recess segment.

A method for identifying broken hooks of needles in a knitting machine, the method comprising:

• providing a welt cam having first and second cam faces for controlling the position of needles in a knitting machine so that intact needles are biased against the first cam face by tension forces between the needle hooks and yams;
• contacting the needle butts with an inclined portion of the second cam face to urge the butts toward the first cam face;
• contacting the needle butts with a declined portion of the first cam face to urge the butts toward the second cam face;
• providing a detector recess segment in which the second cam face is sufficiently spaced from the first cam face so that butts of needles having broken hooks enter the recess due to contact with the declined portion of the first cam face;
• sensing with a sensor that is positioned outside of the detector recess segment a needle having its butt in the detector recess segment;
• and
• stopping operation of the knitting machine when the sensor is actuated.

A needle for use in a knitting machine to form fabric, the knitting machine comprising a cam, a trick channel for housing the needle and within which the needle can reciprocate due to relative movement between the trick channel and the cam, the trick channel comprising an upper end and a lower end, and a sensor that is sensitive to stimulus at a first position proximate the lower end of the trick channel, the needle comprising:

• a hook end for protruding from the upper end of the trick channel;
• a terminating end opposite from the hook end;
• and
• a butt positioned between hook and terminating ends and for sliding along and being constrained by the cam while the needle is used in the knitting machine,
• wherein the terminating end is constructed so that the terminating end:
• is precluded from being in the first position while the needle is intact and used in the knitting machine to form fabric, and
• does move into the first position while the needle is used in the knitting machine and the hook end of the needle is broken.

A needle for use in a knitting machine to form fabric, the knitting machine comprising a cam, a trick channel for housing the needle and within which the needle can reciprocate due to relative movement between the trick channel and the cam, the trick channel comprising an outer end and an inner end, and a sensor that is sensitive to stimulus at a first position proximate the outer end of the trick channel, the needle comprising:

• a hook end for protruding from the inner end of the trick channel;
• a terminating end opposite from the hook end;
• and
• a butt positioned between hook and terminating ends and for sliding along and being constrained by the cam while the needle is used in the knitting machine,
• wherein the terminating end is constructed so that the terminating end:
• is precluded from being in the first position while the needle is intact and used in the knitting machine to form fabric, and
• does move into the first position while the needle is used in the knitting machine and the hook end of the needle is broken.