US2657658A - Loop-taker for sewing machines - Google Patents

Description

No' 3, 1953 R. E. JOHNSON LOOP-TAKER FOR SEWING MACHINES Filed Aug. 28, 1951 Patented Nov. 3, 19S@ UNITED STATES TENT OFFICE LOOP-TAKER FOR SEWING MACHINES Application August 28, 1951, Serial No. 243,935

(Cl. 11B-228) Claims.

The present invention relates to a loop-taker for a sewing machine and more particularly for a lock-stitch sewing machine, such as the looptaker disclosed in the U. S. patent of Kessler, No. 2,085,699, June 29, 1937.

The present invention has for an object to improve the handling of the needle-thread loops by a loop-taker.

Another object of the present invention is to improve loop-takers in such a manner as to lessen the likelihood of needle-thread breakage during the cast-oil` portion of the stitching cycle.

With the above and other objects in mind that will be evident from an understanding of this disclosure, a presently preferred embodiment of the invention is hereinafter set forth in such detail as to enable those skilled in the art to readily understand the function, operation, construction and advantages of it, when read in conjunction with the accompanying drawings in which:

Fig. 1 is a front end elevational View of a looptaker embodying the invention, with fragmentary portions oi certain of the cooperating elements of the sewing machine included.

Fig. 2 is a side elevational View of the looptaker of Fig. 1, again with fragmentary portions of certain of the cooperating parts of the sewing machine included.

Fig. 3 is a vertical sectional View of the looptaker per se, taken substantially on the line 3 3 oi Fig. 2.

Fig. 4 is a fragmentary perspective View of the loop-taker.

Fig. 5 is a vertical sectional view taken substantially on the line 5-5 of Fig. 2.

Fig. 6 is a fragmentary detail sectional view taken substantially on the line 6--5 of Fig. 4.

Fig. 7 is an enlarged view of a portion of Fig. 5 with the thread removed and with the parts in a slightly different relative position.

Figs. 8, 9 and 10 are top plan, side elevation, and bottom plan views, respectively, of the bobbin-carrier retaining gib, the end of which is formed into the loop-controlling tail in accordance with the teachings of this invention.

As illustrated in the drawings, the invention is applied to a lock-stitch type sewing machine including a bed l provided with a throat-plate 2 having a needle-aperture 3 through which an eye-pointed needle 4 is adapted to reciprocate. In the usual manner, goods to be sewed, such as shown at 5, is pressed against the throat-plate 2 by a presser-foot 6, and the goods is fed past the stitching mechanism by a feed-dog 'I carried by a feed-bar 8 which is operated through a fourxnotion type cycle. Secured upon the end of a horizontal-axis rotary shaft 9 underlying the bed i is the cup-shaped hook-body iii of a rotary hook. As will be readily understood, the rotary hook carries a bobbin-thread I2 which is adapted to be concatenated with a needle-thread i3 as the hook and needle coact in the formation of stitches.

The general features of the hooi; are the same as set forth in the above mentioned U. S. Patent No. 2,085,699. Briefly, however, the cup-shaped hook-body Iii includes a circular side wall Il formed with a loop-seizing beak lli and an internal raceway l5 in which is journaled a peripheral bearing rib I6 of a bobbin-carrier il carrying a bobbin-case IS and held against rotation with the hook-body il) by a nger i8 secured to the frame of the machine in any suitable manner and engaging in a rotation restraining notch in a needle-loop controlling ilange It' of the bobbin-carrier. The side wall Il and the bearing rib l5 are both discontinuous. The gap in the bearing rib I6 is indicated by the angle X in Fig. 5, and the ends thereof constitute a loop-detaining shoulder 2K9 and a loop-conning shoulder 2l.

The gap in the side wall H of the loop-taker, measured at the raceway therein, is indicated by the angle Y in Fig. 5. It will also be noted that the greater portion of the raceway i5, which is defined by the angle a in Fig. 3, is not U-shaped but is only a stepped or open-sided groove formed inwardly from the free end of the hook-body It, Fig. 6. That portion of the open-sided portion of the raceway i5 represented by the angle b, Fig. 3, is closed byV an arcuate bobbin-carrier retaining gib 22, L-shaped in cross-section and including a ange 23 comprising the short leg of the L-shaped cross-section projecting inwardly towards the center or curvature. The gib 22 is secured to the outer surface of the side wall il of the hook-body i by screws 2li passing through apertures 25 in the face-plate 25 thereof, which face-plate comprises the long leg of the L-shaped cross-section.

In addition to the gib 22, there is a plate 28 also secured to the outer surface of the hookbody I0. In the customary manner. the plate 28 is formed with a needle-thread deilecting beak 36 at the one end thereof which projects into the gapl in the side wall H adjacent to but spaced from the loop-seizing beak ill of the hook-body l0. The gib 22 also projects into the gap in the side wall Il but from the opposite side thereof from the beak 30, which end of the gib 22 is 3 formed into a loop-controlling tail 3l having a thread-clearance groove 32 extending inwardly in the ange 23 from the tail 3|.

The I -shaped gib 22, which is illustrated per se in Figs. 8, 9 and 10, is substantially constant in transverse cross-section throughout the major portion of its length. The face-plate 26 and the flange 23 of the gib 22 are arcuate, as set forth above, and of constant radius, the radius of the inner surface of the face-plate 26 being substantially equal to that of the outer surface of the hook-body IB, and the radius of the innermost edge of the flange 23 being less than that of the outer surface of the bearing rib I6 but greater than that of the bearing rib at the juncture with the bobbin-case carrier l1. The loop-controlling tail 3l is formed by beveling olf one end of the gib 22 towards that side of faceplate 2i which carries the flange 23, i. e., with the point of the tail 3l formed on the ilange 23.

The groove 32 is cut in the flange 23 at the point of the tail 3l, and is equal in depth to about onehalf of the thickness of the flange.

The lower edge of the ange is preferably of slightly increasing radius towards the point so that the point of the loop-controlling tail 3l is positioned a distance from the axis of hook rotation that is substantially equal to or less than the radius of the outer surface of the bearing rib le. Thus, since the tail 3l is not radially disposed outwardly from the bearing rib and, consequently, since there is substantially no radial spacing between the rib and the point of the loop-controlling tail, there is virtually no opportunity for the Work-limb of the needlethread becoming lodged beneath the tail even though it is retarded in its passage across the bobbin-case face. Also, as seen in Fig. 1, the point of the loop-controlling tail 3| is well removed inwardly from the outer periphery oi the ange I3 on the bobbin-case carrier li which tends to eliminate the tendency for the thread to become lodged beneath the tail.

During normal operation of the sewing machine With the hook rotating in the direction of the arrow in Figs. 1, 3 and 5, the take-up action is adapted to remove the loop of the needlethread from the bobbin-case carrier before the loop-controlling tail 3| passes the loop-coniining shoulder 2l. rIhe necessity of such an arrangement is evident by considering the very high speeds of rotation of the hook, the consequent necessity of a maximum bearing surface between the rib I6 of the bobbin-case carrier and the raceway I5, and the conflicting necessity of increasing the cut-away portion of the rib IB to a maximum to allow suiiicient time to permit withdrawal of the thread loop from the hook. According to the present invention, the conflict is resolved by means of the groove 32. When assembled, theinner surface of the ange 23 Vabuts against the one surface of the rib l and forms a bearing surface therefor. As seen in Fig. 2, because of the groove 32, the point of the loopcontrolling tail and the adjacent portion of the flange 23 is spaced from the rib I8, which spacing provides a clearance by means of which the needle-loop can be withdrawn from the hook before the loop-controlling tail 3l passes the loop-conning shoulder 2|, see Fig. 5.

As will be readily apparent, the device herein disclosed which is constructed in accordance with the present invention is superior to similar prior art devices in that the tendency for the needle-thread to become caught between the bearing rib I6 and loop-controlling tail 3l has been reduced to a minimum by spacing the point of the loop-controlling tail 3| radially inward from the loop-controlling flange I8 and the opportunity for the needle-thread to become so caught is greatly reduced by substantially eliminating the radial spacing between the point Ol' the loop-controlling tail and the bearing rib. The above results, which produce increased efficiency in thread handling, have been obtained without sacrifice of other advantageous features because of the provision of the thread clearance slot S2 between the bearing rib l and raceway l5. The provision of this groove effectively increases the angular distance during which the needle-thread can be withdrawn from the rotary hook while maintaining a maximum bearing surface. t will be noted that the thread groove expedient is useful to enhance the above mentioned desirable features in other types of rotary hooks independent of the specific details of the hook herein set forth.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred ernbodiment of my invention which is for purposes of illustration only and not to be construed as a limitation thereof. All such modifications which do not depart from the spirit of my invention are intended to be included within the scope of the appended claims.

Having thus Vdescribed my invention, what I claim herein is:

l. A sewing machine loop-taker comprising a cup-shaped body having an open-sided raceway internally thereof, a bobbin-carrier having an annular bearing rib disposed in said raceway, a gib adapted to close the open side of said raceway, said gib being provided at one end with a loop-controlling tail terminating in a point which, at a maximum, is spaced from the axis of the loop-taker a distance substantially equal to the radius of the peripheral surface of the bearing rib, the bearing rib engaging surface of the gib being formed with a thread groove adjacent the point thereof to provide a thread clearance between the gib and the proximate face of the rib.

2. A sewing machine loop-taker comprising a cup-shaped body having an open-sided raceway internally thereof, a bobbin-oarrier having a peripheral bearing rib journaled in said raceway, a segmental bobbin-carrier retaining gib secured to the body and having a :flange closing the open side of said raceway, said gib being provided at one end with a loop-controlling tail terminating in a point which, at a maximum, is spaced from the axis of the loop-taker a distance substantially equal to the radius of the outer surface of the bearing rib, the bearing rib engaging surface of the gib being formed with a thread groove adjacent the point thereof t0 provide a thread clearance between the gib and the proximate face of the rib.

3. A sewing machine loop-taker in accordance with claim 2 in which the faces of the flange are substantially planar and parallel to a plane containing the flange-engaging face or the bearing rib.

4. A loop-taker for sewing machines, comprising a cup-shaped body having an open-sided raceway internally thereof, a bobbin-carrier having an annular bearing rib disposed in said raceway, a gib adapted to close the open-side of said raceway, said gib being provided at one end with a loop-controlling tail terminating in a point which, at a maximum, is spaced from the axis of the loop-taker a distance substantially equal to the radius of the peripheral surface of the bearing rib, and a thread clearance slot disposed between said gib and the proximate face of said bearing rib in the vicinity of said loopcontrolling tail.

5. A loop-taker for sewing machines comprising a cup-shaped body having an open-sided raceway internally thereof, a bobbin-carrier having a peripheral bearing rib disposed in said 5 rib in the vicinity of said loop-controlling tail.

RALPH E. JOHNSON.

References Cited in the le of this patent UNITED STATES PATENTS 10 Number Name Date 1,149,049 I-Iemleb Aug. 3, 1915 2,178,543 Rubel et al. Nov. '7, 1939

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