Composite rotary loop taker for lock-stitch sewing machine

A rotary loop taker for high speed rotation about a bobbin basket maintained in a substantially fixed position in a lock-stitch sewing machine below the take-up device of said machine, in which sewing machine the needle provides one of the two threads that together form said lock-stitch, said needle thread being taken off the needle in the form of a loop by the loop seizing point of said rotary loop taker as the loop taker rotates about the bobbin basket, the side wall of said bobbin basket carrying a radially extending rib for engaging the loop taker as the latter rotates about said bobbin basket, which rotary loop taker comprises:

• (a) a frame of substantially annular construction, said frame having an axis of rotation located generally perpendicular to the frame and having a cut-away portion along one segment of its circumference to provide space for the needle thread to exit from the loop seizing point of the rotary loop taker as said thread is pulled off the loop seizing point, said cut-away portion being defined by an end wall of said frame and the forward portion of said loop seizing point facing upon said cut-away portion, the radially inner wall of said frame defining the lower ledge of the middle and final portions of a raceway to receive said rib that extends radially from the side wall of said bobbin basket;
• (b) a frame support member extending crosswise of said substantially annular frame, with one edge portion of said support member facing said cut-away portion of the frame, said edge portion defining a notch adjacent the radially inner wall of said substantially annular frame;
• (c) means for supporting said substantially annular frame for rotation of the same about is said axis of rotation, and about said bobbin basket, during operation of said sewing machine;
• (d) a gib secured to said frame to define the upper ledge of said middle and final portions of said bobbin basket raceway;
• (e) a loop seizing point having a tapered forward end including a base and a free end, with the largest transverse dimensions of said tapered forward end being at said base, said base lying immediately adjacent said substantially annular frame, and the smallest transverse dimensions of said tapered forward end being its said free end, said free end extending circumferentially forward into said cut-away portion of said substantially annular frame,
• said loop seizing point having generally the same circumferential curvature as said substantially annular frame,
• said tapered forward end of the loop seizing point being formed entirely of solid metal from its free end to its base adjacent said substantially annular frame and being integrally formed with the hereinafter described smoothly curved junction;
• (f) a downwardly extending supporting lug included in said substantially annular frame, said lug being integrally formed with said tapered forward end of the loop seizing point and extending directly downward from immediately behind said tapered forward end base,
• said downwardly extending supporting lug forming a smoothly curved junction, free of any seams or joints, with said tapered forward end of the loop seizing point, for guiding said loop of needle thread as it moves from said free end of said tapered forward end down to the rearwardmost position assumed by said loop on the portion of said tapered forward end adjacent its base, and back to said free end again,
• the radially inner walls of said solid metal tapered forward end of the loop seizing point and of said downwardly extending metal supporting lug carrying the leading edge of (i) an upper ledge that defines the upper part of the initial portion of said bobbin case raceway and (ii) a lower ledge that defines the lower part of the initial portion of said bobbin case raceway, said ledges being integrally formed with said tapered forward end of the loop seizing point and said metal supporting lug;
• (g) a metal portion extending rearwardly from said tapered forward end of the loop seizing point at the upper portion of said substantially annular frame, said rearwardly extending portion having an integral shoulder on its bottom inward edge forming the initial portion of said upper ledge;
• (h) means formed of metal for anchoring said loop seizing point to said crosswise support member, said metal anchoring means being integrally formed with said tapered forward end of the loop seizing point, said downwardly extending supporting lug and said smoothly curved junction, said anchoring means (i) extending inward from the bottom portion of said substantially annular frame and away from said tapered forward end of the loop seizing point at least a distance substantially equal to the internal radius of said frame, and (ii) being embedded in and fully encased by said crosswise extending support member of the rotary loop taker, with a plurality of contact surfaces lying within said crosswise extending support member,
• said anchoring means having (i) a first predetermined cross-sectional area measured, in a first plane perpendicular to the direction in which the anchoring means extends away from said tapered forward end, at a given distance from said tapered forward end, and (ii) a larger cross-sectional area measured, in a second plane perpendicular to the direction in which the anchoring means extends away from said tapered forward end, at a greater distance than said given distance from said tapered forward end;
• (i) means for balancing the distribution of the weight of the rotary loop taker angularly and radially about its said axis of rotation, said balancing means being positioned generally on the opposite side of said substantially annular frame from said tapered forward end of the loop seizing point;
• and
• (j) a metal arcuate member that together with said gib forms a retaining ring extending entirely around the outer walls of said rotary loop taker on the exterior thereof, with all portions of said retaining ring being positively connected to each other, to restrain radial expansion of the hereinafter mentioned polymeric material included in said substantially annular frame,
• said rotary loop taker being formed of two different materials, the first of which is a metal of a predetermined type and the second comprising a flowable, hardenable plastic that forms a hard polymeric material having a smooth, slippery exterior surface,
• said tapered forward end of the loop seizing point, downwardly extending supporting lug, leading edges of raceway ledges, lug foot, rearwardly extending portion, and anchoring means all being integrally formed of said metal of said predetermined type, and a substantial part of the rotary loop taker being formed of said flowable, hardenable plastic, said flowable, hardenable plastic material surrounding all said exposed contact surfaces of said metal anchoring means that lie within said crosswise extending support member, in full, intimate contact with said surfaces, and filling all portions of said rotary loop taker not occupied by components thereof that are formed of metal, in full, intimate contact with said metal components, to form a secure, permanent attachment between said metal components and the remainder of the rotary loop taker, the resulting exterior surface of said loop seizing point being smooth throughout its entire area.

A rotary loop taker for high speed rotation about a bobbin basket maintained in a substantially fixed position in a lock-stitch sewing machine in which the sewing machine needle provides one of the two threads that together form said lock-stitch, said needle thread being taken off the needle in the form of a loop by said rotary loop taker as the rotary loop taker rotates about the bobbin basket, which rotary loop taker comprises:

• (a) a substantially annular frame with a cut-away portion along tis circumference;
• (b) means for supporting said substantially annular frame for rotation about the bobbin basket during operation of the sewing machine;
• (c) a loop seizing point attached to the substantially annular frame with a tapered forward end extending into said cut-away portion for taking said loop off the needle, said tapered forward end having a solid metal free end and a substantially metal surface from said free end to a base end attached to the annular frame;
• (d) a substantially annular metal ring attached to the outer wall of said substantially annular frame for retaining the loop taker against radial expansion and creep during rotation about said bobbin basket, a portion of said annular ring being a metal gib attached to the substantially annular frame for retaining said bobbin basket and another portion of said annular ring being a metal arcuate member the inner wall of which conforms approximately to the outer wall of said annular frame, said metal arcuate member having a cam in the axial direction of said frame for facilitating the passing of said loop over the bobbin basket during rotation of the loop taker;
• and
• (e) a fin attached to said metal arcuate member and extending circumferentially rearwardly and radially inwardly into said cut-away portion for directing air radially inwardly between said annular frame and said bobbin basket during operation of the sewing machine,
• said loop taker being substantially of a flowable, hardenable polymeric material.