US3465701A - Controlled loose stitching mechanism for chainstitch sewing machines - Google Patents

Description

Sept. 9, 1969 F. L. WALLING 3,465,701

CONTROLLED LOOSE s rrrcame MECHANISM FOR CHAINSTITCH SEWING MACHINES Filed July 28, 1967 3 Sheets-Sheet l I l l l l l fl I I I l .9 I INVENTOR. Froncis L. Walling BY WITNESS: W .6144. Wad, JQMWAEQZ ATT EY Sept. 9, 1969 F. WALLING CONTROLLED LOOSE STITCHING MECHANISM FOR CHAINSTITOH' SEWING MACHINES 5 Sheets-Sheet 2 Filed July 28, 1967 INVENTQR. Frunqi s L. Wollmg BY W'gORNEY WITNESS: d e/d; 594W Sept. 9, 1969 F. WALLING CONTROLLED LOOSE STITCHING MECHANISM FOR CHAINSTITCH SEWING MACHINES 3 Sheets-Sheet 5 Filed July 28, 1967 I INVENTQR. Froncns L. Wulimg BY v AT ORNEY WITNESS:

United States Patent CONTROLLED LOOSE STITCHING MECHANISM FOR CHAINSTITCH SEWING MACHINES Francis L. Walling, Lincroft, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed July 28, 1967, Ser. No. 656,864 llnt. Cl. D0511 40/02 US. Cl. 112-245 4 Claims ABSTRACT OF THE DISCLOSURE Brief summary of the invention In a conventional chainstitch sewing machine the amount of thread which is utimately used in the formation of each stitch may be controlled only by regulation of the usual thread tensioning devices. A disadvantage of using a thread tension device for providing loose stitches is that as the tension is reduced, the entire stitch concatenation becomes loose and the limiting condition is soon reached in which the thread loops which chain between successive stitches become objectionably distended.

It is also known to produce loose stitching by means of a thread metering device which cooperates with thread nippers. The thread nippers are rendered effective during portions of each stitch forming cycle and only during periods of effectiveness of the nippers is thread drawn from a supply. A disadvantage of a system of thread handling which requires thread nippers is that it does not respond to variations in the character of the work.

The present invention provides -a needle thread metering and controlling mechanism for chainstitch sewing machines which provides for a wide range of preselected looseness in the stitches independently of the setting of the thread tensioning device and which does not require the use of a thread nipper. A plurality of thread controlling devices effective in seriatim on a needle thread between a conventional tension device and the needle serve to draw out and (meter thread from a supply during the downstroke of the needle and to slacken the needle thread during the upstroke of the needle. A stitch is thus provided in which the chain of loops which are set while the needle is down are laid neatly and in controlled fashion while the preselected looseness in the stitch occurs primarily in the needle thread bights from needle penetration to needle penetration. A loose stitch formed in this manner has been found to be advantageously useful in sewing garments which must thereafter be subject to heat treatment as, for instance, in the curing required for finishing permanent pressed garments. Stitched seams which are tight when sewn, are usually puckered after such curing. By proper preselection of the degree of looseness in the stitches, the garment seams after curing can be pucker-free and with the desired ultimate tightness.

Description of the drawings A preferred embodiment of the invention is illustrated in the acompanying drawings in which:

FIG. 1 represents a vertical cross-sectional view of a sewing machine having this invention applied thereto.

FIG. 2 is a top plan view of the sewing machine of FIG. 1 with the top cover removed.

FIG. 3 is an enlarged rear elevational view of a fragment of the bracket arm of the sewing machine of FIG. 1.

FIG. 4 is an enlarged cross-sectional view taken transversely of the sewing machine bracket arm substantially along line 44 of FIG. 2.

FIG. 5 is a perspective view of the thread controlling mechanism for both the needle and looper threads of the sewing machine of FIG. 1.

FIG. 6 is a cross-sectional view taken substantially along line 66 of FIG. 3, and

FIGS. 7, 8 and 9 represent diagramatic perspective views of the needle and loop taker together with a fragment of a work fabric and the needle and looper threads showing respectively the position of the parts and threads at the uppermost of the needle, at engagement of the looper thread loop by the needle during the needle downstroke, and at the lowermost position of the needle.

Detailed description The sewing machine to which this invention is applied as illustrated in the drawings includes a frame comprising a bed 11 with a work supporting plate 12, a standard 13 rising from the bed, and a bracket arm 14 extending from the standard over the bed. For convenience of manufacture and assembly, the bracket arm 14- may be formed open at the top and at the free extremity, and these openings may be closed by a top cover plate 15 and an end cover plate 16, respectively. It will be appreciated, however, that the cover plates 15 and 16 form part of the bracket arm and may be made integral therewith if desired.

Carried lengthwise in the bed 11 is a rotary main shaft 20 having a drive pulley 21 fixed thereto. A thread carrying looper 22 is arranged in the bed and is driven from the main shaft to partake of oscillation lengthwise of the looper for needle looper seizing and shedding, as well as oscillation sideways of the looper to partake of needle avoiding movement. To this end a rock shaft 23 journaled in the bed parallel to the main shaft carries a support block 24 on which a looper carrier 25 is journaled. The rock shaft 23 may be oscillated as by an eccentric or crank drive (not shown) from the main shaft to impart needle avoiding motion to the looper. A rock shaft 26 journaled transversely across the bed carries a rock arm 27 connected by a link 28 to the looper carrier 25 to impart seizing and shedding oscillation to the looper. An eccentric or crank drive (not shown) from the main shaft may be used to oscillate the rock shaft 26. The U.S. Patent of Clayton No. 2,394,510, Feb. 5, 1946, may be referred to for a detailed disclosure of this type of looper oscillating mechanlsm.

As illustrated in FIGS. 1 and 5, spaced looper thread take-up disks 30 fast on the main shaft 20 engage a thread from the looper as the thread passes between a pair of thread guides 3131 and beneath a fixed thread engaging blade 32 extending between the take-up disks. From the take-up disks 30, the looper thread extends to a conventional thread tensioning device 33 and then to a supply (not shown). Preferably, the looper thread take-up mechanism is timed to draw in a loop of looper thread during the loop shedding movement of the looper and to pay out the loop of looper thread during needle loop seizure by the looper.

Indicated at 35 in FIG. 1 is a feed dog of a conventional four motion drop feed mechanism actuated by drive connection (not shown) from the main shaft 20. The feed dog 35 is opposed above the work supporting plate 12 by a presser foot 36 supported in the bracket arm 14.

Journaled lengthwise in the bracket arm 14 is an arm shaft which carries a sprocket 41 driven by a timing belt 42 from a sprocket 43 on the main shaft 20. This main shaft and the arm shaft are preferably connected by the timing belt to rotate each at the same speed. Fixed at the free extremity of the arm shaft 40 is a counterbalanced crank 44 including a crank pin 45 on which is pivoted a link 46 which embraces a stud 47 fast on a needle bar 48. The needle-bar is slidably supported in bushings 49-50 in the bracket arm 14 for endwise reciprocation in response to actuation by the crank 44 and carries at its lower extremity a needle clamp 51 fixing to the needle bar a thread carrying, eye pointed sewing machine needle 52.

The needle thread controlling and metering mechanism of this invention will now be described and the path of the needle thread from the needle to a supply will be traced. From the needle 52 the needle thread extends through a thread guide 59 secured on the needle clamp 51 and then to a very light thread tensioning device 60 on the bracket arm designed to prevent uncontrolled falling of thread toward the needle point as the needle descends. The thread is then directed through an eyelet 61 in a forwardly extending thread take-up bracket 62 which is clamped securely to the top of the needle bar 52 for reciprocation with the needle bar. From the take-up bracket 62, the thread extends to an eyelet 63 formed in an oscillating thread take-up arm 64 protruding through the front wall of the bracket arm. The thread take-up arm 64 is clamped on a rock shaft 65 journaled within the bracket arm parallel to the arm shaft. A rock arm 66 on the rock shaft 65 is pivoted to a pitman 67 driven by an eccentric 68 on the arm shaft so as to oscillate the take-up arm 64 preferably in synchronism with the reciprocation of the take-up bracket 62 on the needle-bar. A thread guiding eyelet 69 formed on a wire loop 70 clamped in selected position by a notched washer 71 and a clamp screw 72 to the front of the bracket arm 14 receives the thread from the take-up arm 64.

From the eyelet 69, the thread passes through a thread guiding tube 73 which is fixed transversely across the top cover plate 15 of the bracket arm. The tube 73 is formed with a rounded mouth 74 at each end so that the thread may be passed from the front to the rear of the bracket arm. The tube 73, moreover, is skewed with respect to the lengthwise direction of the bracket arm as illustrated in FIG. 2 so that the thread entering the tube mouth at the front from the general direction of the free extremity of the bracket arm makes a bend of greater than 90 degrees. Similarly at the tube mouth at the rear of the machine, the thread extending from the tube generally toward the standard 13 makes a bend of greater than 90 degrees. The fractional resistance to movement of thread in the tube which arises due to these sharp bends particularly when the thread is taut, contributes to the favorable metering action of the mechanism of this invention as will be described more fully hereinbelow. The skewed position of the tube 73, moreover, provides for more generous and convenient spacing of the thread controlling elements on the front and back of the bracket arm.

From the tube mouth 74 at the rear of the bracket arm, the thread passes through a pair of spaced thread guiding eyelets 80, 81 preferably formed as an integral wire frame 82. The wire frame 82 includes an elongate loop with substantially parallel limbs 8383 which, as illustrated in FIG. 6, are slidably constained in parallel notches 84S4 of a washer 85 secured to the rear of the bracket arm by a screw 86. An oscillating thread take-up arm protrudes through the rear wall of the bracket arm and is adapted to oscillate in a path between the parallel links 83-83 of the wire loop. The take-up arm 90 within the bracket arm is fast on a rock shaft 91 which is substantially parallel to the arm shaft. A rock arm 92 on the rock shaft is pivotally connected to a pitman 93 driven by an eccentric 94 on the arm shaft. The take-up arm 90 is preferably driven substantially in synchronism with the take-up arm 64 and take-up bracket 62 at the front of the machine. In other words, all three of the movable take-up elements 62, 64 and 90 move downwardly in unison during downstroke of the needle.

The washer 85 is oriented by the screw 86 so that the notches 8484 will constrain the wire links 83-83 of the thread guiding eyelets one at each side of and parallel with the path of motion of the thread takeup arm 90. The vertical position of the eyelets 8081 relatively to the path of motion of the thread take-up arm 90 may be selected by the sewing machine operator by turning a knob at the front of the sewing machine bracket arm. The knob is fast on a shaft 101 journaled in a depending bracket 102 at the front of the bracket arm and a similar depending bracket 103 at the rear of the bracket arm. A rock arm 104 fast on the shaft 101 at the rear of the bracket arm is connected by a pivoted link 105 to the wire frame 82 beneath the constraining washer 85. A frictioning spring between the knob and the bracket 102 may be used to prevent drift or accidental turning of the knob 100.

The thread extending between the eyelets 8081 passes beneath the free extremity of the take-up arm 90 so that on the downstroke of the take-up arm a loop of thread will be drawn in by the take-up arm. The thread loop will be prevented from sliding inwardly along the take-up arm 90 by the parallel links 83-83 of the eyelet wire frame 82. From the eyelet 81, the thread extends to a conventional thread tensioning device and then to a supply (not shown).

The needle thread take-up bracket 62 and the oscillating needle thread take-up arm 64 at the front of the machine operate in concert with respect to the thread from the thread guiding tube 73 to the needle to provide a slackening influence on the thread during the downstroke of the needle and to draw back and provide a tightening influence on the thread during the upstroke of the needle. Indeed the two movable thread take-up elements 62 and 64 without more, provide substantially a conventional needle thread take-up arrangement for a chainstitch sewing machine and if a thread were to be directed from a supply through a conventional tensioning device and then through the guide eyelet 69 and to the needle as described above, conventional needle thread handling would result in that the thread would be slackened on the needle downstroke and tightened on the needle upstroke to set the preceeding stitch and draw from the supply through the tension device an amount of needle thread equivalent to that used in the formation of the preceeding stitch.

The needle thread take-up bracket 62 and the oscillating needle thread take-up arm, therefore comprise a first needle thread take-up means effective to influence the needle thread, as above described, between the stationary thread guiding tube 73 and the needle.

The oscillating needle thread take-up arm 9 operating between the spaced eyelets 80, 81 at the rear of the sewing machine comprises a second needle thread take-up means which influences the thread in a manner opposite to that of the first thread take-up means; that is, the second take-u means draws back a loop of needle thread during the needle downstroke and pays out this loop of thread to slacken the needle thread during the needle upstroke. By means of the operator influenced knob 100, the position of the eyelets 80 and 81 may be regulated so as to preselect the amount by which the size of the loop of thread formed by the second take-up means exceeds that manipulated or given up by the first take-up means.

As a result, during needle penetration on the downstroke of the needle the combined effect of the first and second take-up means will be to remove all slack from the needle thread system and to draw into the system through the tensioning device 110 an amount of thread equal to that used in the preceeding stitch formation. On the upstroke of the needle a controlled slackness will exist in the needle thread so that a loose needle thread from one stitch to the next will be obtained. The greater the loop of thread formed by the second take-up means on the needle downstroke, the looser will be the needle thread in the resulting stitches. This looseness will be maintained uniformly as between successive stitches even through the work thickness varies because the second take-up means will always meter through the tension device 110 that amount of needle thread which was consumed in the immediately previous stitch.

While needle thread is being metered from the supply through the tensioning device 110 by the second take-up means, the thread leading to the needle will be taut and the frictional resistance to movement imposed upon the thread leading into and out of the tube 73 at relatively sharp angles will accordingly be relatively high. As a result the tension which will exist on the needle thread in the vicinity of the needle will be considerably lower than the tension which will exist on the thread in the vicinity of the second take-up means.

FIGS. 7, 8 and 9 illustrate diagramatically various critical positions of the stitch forming instrumentalities during a typical stitch forming cycle together with the disposition of the threads under the influence of the controlling and metering mechanism of this invention. In these figures, N indicates the needle thread and L indicates the looper thread.

FIG. 7 illustrates the position of parts at the top of the needle stroke. The needle and looper threads in this position are both slack and as the work is fed the needle thread will drape loosely from one needle penetration to the next.

FIG, 8 shows the position of parts as the needle decends into the looper thread loop. Here the needle thread will be taut and it is in this position of parts that thread will be metered from the supply through the tensioning device 110. The needle thread loop from the previous needle penetration will, however, remain on the looper in this position of parts and thus prevent the concatenation of threads made at the previous needle penetration from being drawn up tight.

FIG. 9 illustrates the position of parts at the bottom of the needle stroke. Both the needle and looper threads are taut at this point, and the needle thread loop from the previous stitch will have been shed from the looper and will have shortened somewhat. The tension existing in the looper thread at this time will, however, prevent the shed needle thread loop from shortening to any great degree and because of the imposition of friction resistance to the taut needle thread by the sharp angular bends on entering and emerging from the tube 73, the needle thread at the stitching point will not be excessively tensioned. In the position illustrated in FIG. 9 both the needle and looper thread take-up mechanisms have drawn back the maximum amount of thread and will immediately thereafter begin to slacken the threads.

The resulting seam provided by the operation of the needle thread controlling and metering mechanism of this invention possesses a regulatable degree of looseness particularly in the needle thread so that the stitched seam may later be subjected to processing such as permanent press finishing which shrinks the sewing threads without resulting in puckering of the seam.

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

1. A needle thread metering and controlling mechanism for a chainstitch sewing machine having a frame including a work support, a thread carrying work penetrating needle mounted in said frame, and actuating means in said frame for imparting endwise reciprocating movement to said needle, a needle thread tensioning device carried on said frame, stationary thread guide means carried on said frame for accommodating a thread passing from said tensioning device to said needle, a first movable thread take-up means operatively connected with said actuating means and effective to manipulate a loop of thread between said stationary thread guide means and said needle for paying out said thread loop during the work penetrating stroke of needle reciprocation and drawing in said thread loop during the withdrawal stroke of said needle reciprocation, a second movable thread take-up means operatively connected with said actuating means-and effective to manipulate a loop of thread between :said stationary thread guide and said tensioning device for drawing in said thread loop during the work penetrating stroke of needle reciprocation and paying out said thread loop during the withdrawal stroke of said needle reciprocation, and operator influenced regulating means for preselecting the amount by which size the loop of thread manipulated by said second take-up means exceeds the size of the loop of thread manipulated by said first take-up means.

2. A needle thread metering and controlling mechanism as set forth in claim 1 in which said sewing machine frame includes a lengthwise elongate bracket arm in which a needle-bar is mounted and in which said first needle. thread take-u means is arranged at the front of the bracket arm, said second needle thread take-up means is arranged at the rear of the bracket arm, and said stationary thread guide means comprises a thread guiding tube secured transversely from front to rear of said bracket arm.

3. A needle thread metering and controlling mechanism as set forth in claim 2 in which said bracket arm is mounted to have a free extremity and in which said needle is mounted in the free extremity of said lenghtwise elongated bracket arm, said thread guiding tube includes a mouth at the rear and a mouth at the front of said bracket arm, both of said tube mouths being from said extremity thereof, said first needle thread take-up means being located toward the free extremity of said bracket arm from the tube mouth at the front of said bracket arm, said second needle thread take-up means being located at the side opposite the free extremity of said bracket arm from the tube mouth at the rear of said bracket arm, and in which a line joining said tube mouths is skewed relatively to the length of said bracket arm and provides for angles of greater than degrees in the thread leading into and out of said tube mouths.

4. A needle thread metering and controlling mechanism as set forth in claim 1 in which said second needle thread take-up means comprises a thread engaging arm constrained to move in a predetermined path, a pair of thread guiding eyelets one at each side of the path of said thread engaging arm, means shiftably supporting said pair of thread guiding eyelets on said frame for movement in a path substantially parallel to the path of said thread engaging arm, said operator influenced means comprising an operator influenced linkage carried on said frame and connected to said pair of thread guiding eyelets for maintaining said pair of thread guiding eyelets in selected position relatively to said thread engaging arm.

References Cited UNITED STATES PATENTS 1,439,468 12/1922 Gatchell 112241 1,569,992 1/1926 McCann 112--242 2,327,838 8/1943 Zeier 1l2246 2,626,580 1/1953 Koenig 112-242 2,730,061 1/ 1956 Czajkowski 112--254 3,140,682 7/1964 Hale et a1 112--242 MERVIN STEIN, Primary Examiner GEORGE H. KRIZMANICH, Assistant Examiner

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