US2250121A - Loop-taker for sewing machines - Google Patents

Description

July 22, 1941. s. zoms LOOF-TAKER FQR SEWING MACHINES Filed Feb. 21, 1940 Patented July 22, 1941 UNITED STATES oreice 2,250,121 7 LOOP-TAKER FOR SEWING MACHINES Application February 21, 1940, Serial No. 320,100

4 Claims.

This invention relates to stitch-forming mechanisms of sewing machines adapted for operation at high speeds and employing loop-takers, more particularly of that class in which a rotary loop-seizing member is formed with an axial thread-cavity and in which is journaled a threadcarrier restrained against rotation with said member.

The primary object of the present invention is to improve the thread-handling capacity at high speeds of a loop-taker of the class above referred to, thereby to minimize thread-breakage and the formation of undesirable knots or loose thread-loops at the under side of the Work. Other and more specific objects of the invention will be apparent from the following description and claims.

The invention consists in the improvements in sewing machine loop-takers as hereinafter described in connection with the accompanying drawing which illustrates a preferred embodiment of the invention and in which Fig. 1 is a front end elevation of a sewing machine containing the present improvements. Fig. 2 is an enlarged perspective view,- partly in section, of the loop-taker, including the threadcarrier journaled therein and a needle-thread loop abnormally disposed between the loop-taker and thread-carrier. Fig. 3 is an enlarged perspective view of the thread-carrier about which needle-thread loops are cast by the loop-taker.

The frame of the machine includes the usual work-supporting bed-plate I and overhanging bracket-arm terminating in a head 2, in which is journaled an endwise, vertically reciprocating needle-bar 3 carrying at its lower end an eyepointed needle 4, said needle-bar being actuated by any usual or suitable needle-reciprocating mechanism.

Also carried by said bracket-arm head 2 is a needle-thread take-up mechanism comprising rotary thread-engaging elements 5 performing one rotation for each complete needle-reciprocation, and supplemental rotary thread-engaging elements 6 performing two rotations for each rotation of the thread-engaging elements 5. A take-up mechanism of this character is more fully shown and described in my prior U. S. Patent No. 2,191,736, Feb. 27, 1940.

The work is advanced past the stitch-forming mechanism by a feed-dog I of the drop-feed type, which feed-dog may be actuated in any usual or suitable manner. Opposed to the feeddog I is a presser-foot 8 attached to the lower end of a spring-depressed presser-bar 9 which is endwise vertically movable in the bracketarm head 2.

Complemental to the needle 4 and cooperating therewith below the bed-platel in the formation of lock-stitches is a rotary loop-taker ID of the horizontal-axis rotary hook type performing two rotations for each complete needle-reciprocation. A loop-taker of this type is shown and described in the U. S. patent to C. A. Kessler, No, 2,085,699, dated June 29, 1937. Any usual or suitable actuating mechanism may be employed for rotating the loop-taker l0 which, in general, has a cup-shaped body providing an axial thread-cavity. The side Wall II of the loop-taker body is cut away to provide a threadloop seizing beak l2, and overhanging said beak [2 in spaced relation thereto is a thread-loop deflecting member l3. Spaced circumferentially from as well as directed oppositely to said beak i2 is a loop-discharging tail or spur [4 extending from a segmental gib l5 suitably secured to the loop-taker body, said spur being illustrated in dotted lines in Fig. 2.

The side Wall ll of the loop-taker body is internally provided with an annular thread-carrier raceway IS, in which is j-ournaled the peripheral bearing-rib ll of a thread-carrier I8 containing a mass of under thread and suitably restrained against rotation with the loop-taker. The bearing-rib i1 is as usual cut away to provide a thread-loop arresting shoulder I 9 and an opposed thread-confining shoulder 29, said shoulders l9, 2!] defining therebetween a thread-clearance gap 2| in which one limb of the needlethread loop is disposed as said loop is cast about the thread-carrier l8 by the loop-taker, and through which gap 2| the needle-thread loop is discharged preparatory to final drawing up of the needle-thread loop and setting of the stitch.

The mode of operation of the loop-taker Ill in casting a needle-thread loop about the threadcarrier I8 is well understood in the art. In general, when the needle 4 has completed its descending movement and begins to rise, it throws out a needle-thread loop which is entered by the loop-taker beak l2. When seized by the loop-taker, the limb of the needle-thread loop anchored in the work, i. e., the work-limb of the needle-thread loop, is disposed at the inner side edge of the beak l2, and the limb of the threadloop leading through the work to the needle, i. e., the take-up limb of the needle-thread loop, is disposed at the outer side edge of the beak l2.

. The initially inner or work-limb of the threadloop entered by the beak I2 is engaged by the outer edge of the thread-deflecting member I3 which overhangs said beak, whereby the worklimb of the thread-loop is deflected outwardly and is thereby carried by the loop-taker across the outer or exposed face of the thread-car'- r'ier IS.

The initially outer or take-up limb of the needle-thread loop entered by the beak I2 is engaged at the under side of said beak by the bearing-rib shoulder I9 of the thread-carrier I8 and is confined by said shoulder to pass through the bearing-rib gap 2|, whereby in the continued rotation of the loop-taker the take-up limb of the thread-loop which passes through the gap 2| is enlarged and is forced to pass across the inner side face of the thread-carrier disposed adjacent the bottom wall of the iooptaker body.

When the loop-taker beak I2 has progressed approximately one half a revolution from loop-' cast-off by the loop-taker beak IZ'is, in the normalfunctioning of the loop-taker, caught by the loop-discharging spur I4, and is held thereby while the loop is progressively reduced in size by thetake-up'and untilthe spur I4 is disposed adjacent the bearing-rib gap 2|, at which point the spur I4 casts off the thread-loop and the latter is now free to be finally drawn up by the take-upinto interlocking engagement with the thread-1eading from the thread-carrier I8, thereby completing the stitch "formation.

Should the thread-loop when drawn off the loop-taker beak I2 by the take-up fail to be caught by the oppositely directed loop-discharging spur I l, said. thread-loop will abnormally pass under said spur and will be drawn by the take-up between the inner face of the sidewall II of the loop-taker body and the bearing-rib I of the thread-carrier. The action of the takeup-at thistime to reduce the size of the threadloop isvery rapid and when the thread is abnormally engaged by and pinched between the bearing-rib I1 and the loop-taker body, the takeup is hindered in performing its function of drawing up the thread-loop. This may result in thread breakage, but -it may also result in causing the take-up todraw needle thread from its source of supply, whereby knots and loose thread-loops are formed at the under side of the work.

In order to reduce thelpossibility of the threadloop from passing under-the spur I4, the threadcarrier I8 is preferably provided circumferentially thereof with a segmental guard-rib 22 disposed between the inner side edgev of the threadcarrier and the bearing-rib II. The guard-rib 22 terminates at one endin a shoulder 23 disposed adjacent the thread-confi'ning shoulder 2E1 of the bearing-rib II, whereby -the guard-rib shculder23 supplements the bearing-rib shoulder 2!! in determining the position of the threadloop wherein it is free to be drawn up through the clearance-gap 2|.

A guard-rib of the character described is disclosed in the U. S. Patent to J. C. Ringo, No. 1,292,063, Jan. 21, 1919, and had for its function to shield the thread-loop inits traverse from the beak of the loop-taker to the opposed spur thereof from rubbing upon or en agin the bearing-ribof the thread-carrier and becoming soiled thereby. By thus lifting the thread-loop above the bearing-rib II, the guard-rib 22 also functions in the present case to minimize the possibility of the thread-loop passing under the spur I4.

In order to still further reduce the liability of thread-breakage and the formation of knots and loose thread-loops at the under side of the work, the bearing-rib I! of the thread-carrier is provided adjacent the thread-confining shoulder 2E) thereof, i. e., at the cast-ofi or discharge side of the bearing-rib gap 2|, with a plurality of circumferentially closely spaced relief-notches 24. The relief-notches 24 which terminate at the bearing-rib shoulder 23 preferably begin at a point in the bearing-rib I? wherein a threadloop will abnormally pass under the spur I4, said relief-notches also being preferably inclined from the outer toward the inner side faces of the bearing-rib in the direction of rotation of the looptaker.

Should a thread-loop abnormally pass under the spur I4 of the loop-taker, said thread-loop when overlying any one of the relief-notches 24 is free to be drawn up by the sewing machine take-up. The lands of the bearing-rib between the relief-notches 2d are sufficiently narrow so that in passing from one to the succeeding one of said notches, the thread-loop is only momentarily detained by said lands, and the elasticity of the thread accommodates this momentary detention. Consequently, the relief-notches 2 3 permit the take-up to perform its function of drawing up the needle-thread loop, even when the thread-loops are not caught by the spur It. By lifting the thread-loop, the guard-rib 22 creates a lead of the thread-loop favorable to the passing of the thread-loop from one to another of the relief-notches 24, as will be self evident.

As hereinbefore described, it is the take-up limb of the thread-loop which passes across the inner face of the thread-carrier I8. Consequently, the take-up acts primarily upon said inner limb when drawing up the thread-loop. In so doing, the inner limb is shortened faster than the work-limb of the thread-loop, and accordingly at the time when the thread-loop may pass under the spur It, the thread extends obliquely scross the outer face of the thread-carrier I8, as illustrated in Fig. 2 of the drawing. It is to meet this condition that the relief -notches 24 are preferably correspondingly inclined, as before described.

Having thus set forth the nature of the invention what I claim herein is:

1. In a rotary loop-taker for sewing machines, comprising a cup-shaped body having its side wall provided with a thread-loop seizing beak and with a thread-loop discharging spur directed oppositely to said beak, said body being internally provided with an annular thread-carrier raceway, and a relatively stationary thread-carner having an interrupted peripheral bearing-rib journaled in said raceway and providing a thread-loop receiving gap between said loop-taker body and said thread-carrier, the improvement which consists in providing said bearing-rib with a plurality of circumferentially spaced relief-notches disposed thereindirectly adjacent to and at the loop-discharge side of said thread-loop receiving gap, thereby to provide clearance for thread abnormally discharged from. said beak under said spur.

2. In a,rotaryloop-takerfor sewing machines, comprising a cup-shaped body having its side wall provided with a thread-loop seizing beak and internally with an annular thread-carrier raceway, and a relatively stationary thread-carrier having an interrupted peripheral bearing-rib journaled in said raceway, said interrupted bearing-rib providing a thread-loop arresting shoulder at the cast-on side of said thread-carrier and an opposed thread-confining shoulder at the cast-off side of said thread-carrier, the improvement which consists in providing said bearingrib with a plurality of circumferentially closely spaced relief-notches disposed therein adjacent to said thread-confining shoulder.

3. In a rotary loop-taker for sewing machines, comprising a cup-shaped body having its side wall provided with a thread-loop seizing beak and internally with an annular thread-carrier raceway, and a relatively stationary thread-carrier having an interrupted peripheral bearing-rib journaled in said raceway and providing a threadloop receiving gap between said loop-taker body and said thread-carrier, the improvement which consists in providing said bearing-rib with a plurality of circumferentially closely spaced reliefnotches disposed therein directly adjacent to and at the loop-discharge side of said thread-loop receiving gap, said relief-notches being inclined upwardly toward the inner face of the threadcarrier.

4. In a sewing machine loop-taker having a loop-seizing beak, a loop-discharging spur disposed oppositely to said beak, a thread-carrier having an interrupted bearing-rib journaleci within said loop-taker and providing a thread-loop receiving gap between said loop-taker and said thread-carrier, and said thread-carrier being provided circumferentially thereof with a guardrib disposed between said bearing-rib and the inner face of the thread-carrier at the cast-01f side of said thread-carrier, the improvement which consists in providing said bearing-rib with a plurality of circumferentially closely spaced relief-notches disposed therein directly adjacent said guard-rib and extending to said thread-loop receiving gap.

SYDNEY ZONIS.

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