US1740808A

US1740808A - Overseaming sewing machine

Info

Publication number: US1740808A
Application number: US95382A
Authority: US
Inventors: Charles R Colt
Original assignee: Willcox and Gibbs Sewing Machine Co
Current assignee: Willcox and Gibbs Sewing Machine Co
Priority date: 1926-03-17
Filing date: 1926-03-17
Publication date: 1929-12-24
Anticipated expiration: 1946-12-24

Description

Dec 24, 1929. c, R, COLT 1,740,808

OVERSEAMING SEWING MACHINE Filed March 17, 1926 10 Sheets-Sheet l Dec. 24, 1929. c, R; COLT 1,740,808

OVERSEAMING SEWING MACHINE Filed March '17, 1926 10 Sheets-Sheet 2 Dec. '24, 1929. c. R. COLT OVERSEAMING SEWING MACHINE Filed March 17, 1926 10 Sheets-Sheet 3 MW. 3 Wk Q I. MW. 0 MN HQ, Q G O \m m 1 kw w m mm QM km, W o Q\ h Q k% m Zlwuentoz Dec; 24, 1929, R, COLT 1,740,808

OVER SEAMING SEWING MACHINE Filed ar 17, 1926 10 Sheets-Sheet t I v v glwuentoz WM 351 m Gum/Lo Dec. 24, 1929. c. R. COLT OVERSEAMING SEWING MACHINE Filed March '17, 1926 10 Sheets-Sheet 6 k I am t (wk-t m1, W gw m MY Dec. 24, 1929. c. R. COLT OVERSEAMING SEWING MACHINE Filed March 17, 1926 10 She ets-Sheet j-nwzwroz m l6 M Dec. 24, 1929. c. R. COLT OVERSEAMING SEWING MACHINE Filed March 17, 1926 10 Sheets-Shet 9 Dec. 24, 1 929. c. R. COLT 1,740,808

OVERSEAMING SEWING MACHINE Fil d March 1926 10 Sheets-Sheet 10 Patented Dec. 24, 1929 UNITED STATES PATENT OFFICE I CHARLES R. COLT, OF BROOKLYN, NEW YORK, ASSIGNOR TO WILLCOK 8a GIBBS SEWING MACHINE COMPANY, OF NEW YORK, N. Y,, A CORPORATION OF NEW YORK- machines.

the overlook 10 cable to sewing OVERSEAMING SEWING MACHINE Application filed March 17, 1926. Serial No. 95,382.

This invention relates to sewing machines and particularly to overseam or overedge Although designed with special reference to what is commercially known as sewing machine of the Willcox & Gibbs Sewing Machine Company, such as substantially shown in Willcox and Borton Patents Nos. 472,094, and 472,095, both dated April 5, 1892, this invention is applimachines generally.

Some of the objects of the present invention are the provision of an overseam sewing machine employing three threads in the formation of stitches, that .is one needle thread and two looper threads; the provision of such a machine capable of operating at high speed; and the provision of such a machine of the general type and construction of the aforesaid overlook machine except for differences in construction necessary to an embodiment of this invention.

Another object is the provision of loopers and looper actuating means such as may be substituted for the looper mechanism in said two-thread overlook sewing machine to convert the same into a three-thread overseaming machine, and generally the provision of parts and mechanism which may be used in place of, or in addition to, parts of said over lock machine whereby the latter or parts thereof may be employed to constitute the basis, or nucleus, of an embodiment of the present invention. 7

It has been customary in sewing machines and particularly in overseaming or overedge sewing machines to actuate the looper or loopers thereof by eccentrics or cams which impart to the loopers length of travel or movement much in excess of what is required for concatenation of the threads into the stitches; which cause considerable overthrow of the loopers at the ends of each reciprocating movement thereof particularly when operating at high speeds, and which also cause considerable shocks and vibrations in stopping and starting the loopers at the ends of each reciprocation thereof. Such excessive movements of the looper or loopers pull ofi excessive amounts of both looper and needle threads which have to be taken up in setting the stitches; such overthrow of the loopers also pulls off still other extra thread for which no take-up provision has been made with the result of loosely set and hence malformed stitches; and such shocks and vibrations result in excessive noise, wear, and strain, and are otherwise objectionable.

Other objects of the present invention are the provision of a sewing machine particularly a high speed overseam sewing machine, wherein overthrow of the looper, or loopers, will be minimized or practically eliminated; wherein the looper or loopers willhave an extended dwell at both ends of the movement thereof; wherein the usual shocks and vibrations incident to starting and stopping of the looper or loopers will be minimized or practically eliminated; wherein each movement of the looper, or of each looper, from one position of dwell to the other, will be at a gradually accelerating speed followed by a gradually retarding or diminishing speed, with the result of minimizing or practically eliminating shocks and vibrations resulting from looper movements; wherein the movement or travel of the looper or loopers will be shortened to an approximate minimum, hereby enabling the speed of movement of the loopers to be slower, the needle movement to be shorter in length and slower in speed, and generally resulting in better handling of the looper and needle threads and formation and setting of the stitches.

Still further objects of the invention are the provision of improved thread-control means whereby very tight stiches may be made, and of such means capable of being applied to the aforesaid overlook machine in conjunction with the aforesaid improved looper mechanism in transforming said prior machine into an embodiment of the present invention.

The aforesaid and still other important objects hereinafter explained or apparent from the detailed description and drawings are attained by this invention and by the now preferred mechanical embodiment thereof illustrated in the accompanying drawings wherein the invention is shown as applied to or embodied in a machine ofthe type of the aforesaid overlook.

Fig. 1 is a plan view of an overlook sewing machine embodying my invention and show ing the moving arts in position with the point of the nee e {ust enterin the work;

Fig. 2 is a front e evation of t e complete machine with its casing 'orbox shown in section and the moving parts 1n position with the needle at the end of its upward. move ment;

Fig. 3 is an elevation lookin from the left hand side of the machine with the casing shown in section and with the moving parts shown in the same position as in Fig. 2;

Fig. 4 is a bottom plan view of hinged cover of the casing and the mechanism mounted thereon and with the moving parts in the same position as in Fig. 2;

Fig. 5 is a horizontal sectional view on line 5-5 of Fig. 2, some of the parts being shown in plan v1ew Fig. 6 is a vertical of Fig. 4;

Fig. 6 is a detail bottom plan view from beneath the work-plate showin the under looper in its starting position re ative to the feed and needle; I

Fig. 6 is a detail sectional view taken on section on the line 6-6 the line 6"--6 of Fig. 6";

Fig. 7 is an enlarged perspective view of the looper mechanism;

Fi 8 is a diagram illustrating the approxlmate relative timing of the needle,

needle thread control, upper looper, upper looper thread control, under looper, and under looper thread control;

Fig. 9 isa detail plan view showing the needle plate and associated feed dogs;

Fig. 10 is a detail sectional view showing the thread controlling lever for the looper threads and the means for actuating the same;

and Figs. 11, 12, 13 and 14 are enlarged views showing more or less diagrammatically different stages in the formation of an overlock stltch by the machine herein illustrated and describedand the approximate relative posi- Y tions of the needle and loopers at each stage.

While the accompanying drawings show the invention as applied to a standard Will- I cox & Gibbs overlock machine, it is to be understood that the invention is also applicable to sewing machines of other types. As much of said overlook machine as may be necessary to a clear understanding of the application of the invention thereto will be described. 5 is a box casing or bed-plate havmg a cover or workplate 6 hinged thereto by a pivot rod 7 at the rear of the casing and formed with a depending oil well 8., The entire mechanism of the sewing machine is mounted on said cover or work-plate 6 so as the same to be swung upwardly when it is desired to have access to those of A curved needle 9 is secured by a clamp 10 to the end of a needle arm or lever 11. This lever extends rearwardly in the direction of feed and at its rear end downwardly through an opening in the work-plate 6 and is fulcrumed on a countershaft 12 which is 10111- naled in hearings on the under side of said work-plate. A main rotatable shaft 13 is also'journaledin hearings on the under side of the work-plate and is located in front of and parallel to the countershaft 12, both shafts extending at right-angles to the line of feed. The needle lever 11 is reciprocated by an eccentric 14 on the main shaft 13 which actuates a pitman 15 pivoted at 16 to said needle lever.. The work-plate 6 carries a needle-plate 17, Fig. 9, having a-needle opening 18 through which the needle 9 .reciprocates and also having front feed openings 19 disposed in front of the needle opening and rear feed openings 20 disposed in rear of the needle opening. feed bar 21 below work-plate 6 carries at its forward end a front feed dog 22 which operates in the front feed openings 19 and a rear feed dog 23 which operates in the rear feed openings 20. The feed dogs are arranged in tandem and portions thereof are in front of and in the rear of the needle'opening and in line therewith. The front feed dog 22 has an offset shank 24, Fig. 6, which is secured to the front end of the feed bar. The rear feed dog 23 has a shank 25 secured to a lug 26 extending laterally from the feed bar proper 21. There is thus provided a space 27 directly below the needle openin and between the shanks of the feed dogs, as s own in Fig. 6. The feed bar 21 is disposed wholly on the left-hand side of the needle opening and the front end thereof extends forwardly beyond the lug 26 and terminates at a point slightly in front of the needle opening. This feed bar and feed dogs thereon are given the usual four motions; that is,.up and down, and back and forth. A frame 28 on the feed bar 21 embraces a feed lift eccentric 28, Fig. 5, on the main shaft 13, and thereby up and down movements are imparted to the feed bar. Backward and forward movements are iin parted to said feed bar 21 by a feed rocker 29 actuated through a bar 29 by an eccentric 30 on the main shaft 13. The bar 29 is connected with the feedrocker 29 by a pivot pin and segmental slot adjustable connection 29 for varying the length of feed stroke and thereby the length of stitch formed. The four-motion feed mechanism described above is of the same construction as that embodied in the well known commercial overlook machine hereinbefore mentioned; hence further detailed description thereof is believed to be unnecessary. 4

needle-plate 17 and with" both

feed dogs

22 and 23 to intermittently feed the, work past the needle. This presser-foot is mounted on the front end of a forwardly extending presser-foot bar 32 having an integral sleeve at its endwise by a lever mechanism which is desigrear end embracing and secured to a shaft 33 journaled in bearings extending upwardly from the work-plate 6. A rock-arm 34 also integral with said sleeve cooperates with a hand-actuated cam-lift lever 35 fulcrumed on the work-plate 6. A coiled spring 36 bears at its upper end against an overhanging shoulder of a post 37, Fig. 2, fixed to the work-plate 6 and at its lower end against a lateral extension 32, Fig. 2, of the presserfoot bar 32, thereby yieldin'gly holding the presser-foot in engagement with thework. 'l o 11ft the Presser-foot the forward end of the cam lever 35 is lifted, rotating said lever on 1t-s pivot at its rear end and causing its cam surface 35 to act against a roller 34 on the outer end of arm 34, thereby rocking shaft 33 and in turn lifting bar 32 and with it the 1presser-foot 31 at the forward end of said A vertically reciprocatory trimmer-blade 38 cooperates with a stationary trimmerblade 39, the latter being mounted on the work-plate 6, and these blades function at a pomt in advance of the needle to trim the edge of the work or fabric prior to the formation of stitches about the thus trimmed edge. The movable blade 38 is clamped to the forward end of a trimmer-arm or lever 40 which at its rear end is secured to and fulcrumed on a shaft 41 ournaled in bearings on the work-plate 6. Lever 40 is moved up and down on its fulcrum by an eccentric 42 on the main shaft 13 actuating a connecting bar 43 pivoted at its upper end to the trimmer-arm 40. The shaft 41 and thetrimmerarm 40 fixed thereto are adapted to be moved nated as a whole by the numeral 44, thus enabling the trimmer-blades :to be shifted laterally to vary the width of the trimmed edge portion or margin through and about whlch the stitches are to be formed, and correspondmgly varying the width of the stltches.

The parts and mechanism thus far described by the'use of reference numerals, as well as still other parts illustrated in the accompanying drawings and to which parts 1t 1s herein unnecessary to make specific reference, are substantially the same as corresponding parts in the aforesaid standard overlock sewing machine and in said VVillcox and Borton patents to which reference is made for further detailed description.

Heretofore in sewing machines employing a needle and cooperating threaded under looper, said needle and looper have been actuated by-an eccentric, the length of the reciprocatory stroke of the looper being substantially equal to the length of the needle travel or movement. This condition has necessarily caused the looper by its loop-taking movement to produce a needle thread loop around the looper containing considerably more thread than has been used in the formation of the stitch under construction. Also a considerable amount of needle thread has been pulled from the needle thread supply in excess of the amount of thread necessary for use in the formation of the stitch under construction. Consequently it has been necessary to take up this excess needle thread and excess looper thread by proper thread-controlling means operating during the formation of each stitch. Furthermore, in such machines, the looper, in its return stroke, does not shed the surround-ing needle thread loop until.the needle nearly reaches the lower end of its stroke, with the result that but a very small portion of the downstroke of the needle is utilized in drawing up the needle loop to the underside of the work. This condition has necessitated the employment of additional means for setting the stitch. Furthermore, the reciprocating looper has been brought to a sudden stop at each end of each reciprocating movement thereof and then, following its period of rest at each end of such movement, has been suddenly started, such sudden stopping and starting producing shocks, and the sudden stopping also resulting in overthrow of the looper of an amount depending upon the speed and length of travel of the looper. Such overthrow has the decided disadvantage of .pulling from the source of thread supply excess needle thread and looper thread which, by reason of the thread-control being constant, has been left in the formed stitches, resulting in loose setting of the stitches. The improved looper mechanism and thread controlling mechanism of the present invention overcome the aforesaid difiiculties and objections.

The new parts and mechanisms, whlch 1n themselves and in conjunction and combination with the' old parts already referred to in the detailed description constitute the herein disclosed embodiment of the present invention, will now be described.

Two thread-carrying loopers are employed, one an under looper 46 cooperating with the needle 9 below the work, and the other anupper looper 47 which cooperates with the needle above the work and with the looper 46 in proximity to the edge of the work or fabric around which edge the stitches are being formed. 48 is a hanger, or what may be termed the cam-slide hanger, because it accommodates cam-actuated slides as will later appear. Hanger 48 is of general U-shape or Y-shape having at the upper ends of its two

arms

49 and 50 flat surfaces bearing against the under surface of the workplate or cover 6 and secured thereto by

screws

49 and 50 respectively. As thus appears, the

arms

49 and 50 .of the hanger 48 are located on opposite sides respectively of the needle hole 18 and the feed bar 21.

Arms

49 and 50 of the hanger 48 are joined by the connecting portion 51, the plane of which is below that of the main shaft 13 and from the middle of which portion 51 there is a depending part 52 having therein a vertical guide- Way or slideway 53 closed at one side by a cover-plate 52 secured in place by screws shown in dotted'lines in Figs. 3'and 6, said guideway being thus located directly under the main shaft 13. The under looper 46 in? cludes a beak 54 on a shank portion which latter fits and is secured by a set-screw in the socket of a looper carrier 56 which has a are parallel to each other and also to the line of feed. It follows that both loopers will be reciprocated in parallel vertical planes transverseto or at right angles to the line of feed. The looper mechanism is soconstructed as to position the beak 54 of the under looper 46 as close as possible to the under side of the work-plate 6 to thereby reduce the length of needle thread which forms the loop of needle thread into which said beak 54 enters and thus lessen the amount of needle thread which must be taken up after said loop has been shed from the looper.

The

loopers

46 and 47 are reciprocated in proper timed relation to each other and to the needle 9 by earns 62 and 63 respectively, said cams being of the peripheral type and located on the main'shaft 13 between the needle lever eccentric 14 andthe feed lift eccentric 28, as shown in Fig. 5, and said cams being thus also directly above the guideway 53 in the depending part 52 of the cam-slide hanger 48. 64. and 65 are

camslides having bars

66 and 67 respectively fitting and working side by side in the guideway 53 of the depending part or arm 52 of hanger 48. At its upper end cam-slide 64 has a frame-like portion surrounding and embracing the cam 62 and including a removable cap section 64. At its upper" end cam-slide 65 has a frame-like portion surrounding and embracing the cam 63 and including a cap section'65 removably secured in place by screws shown in dotted lines in Fig. 6. Similar screws secure the cap section 64" in place. The part 52 on the camslide hanger 48 depends into the oil well 8 of the box casing so that the cam-slides working in the guideway of said part are constantly and adequately lubricated by oil in said end a pivotal'connection 69 to the lower end of an upright link 70 which has at its upper end a pivotal connection 71 to the outer end of a rock-arm 72 which is fixed at its other end to the stud or shaft 57 of the carrier 56 for the underlooper 46. The cam-slide 65 similarly has a forwardly extending angular arm 73 having at its outer end a pivotal connection 74 to the lower end of an upright link 7 5 which has at its upper end a pivotal connection 76 to the outer end of a rock-arm 77 which is fixed atits other end to the stud o'r shaft 61 of the carrier for the upper looper 47. The rock-

arms

72 and 7 7 are slightly curved (see Figs. 2 and 7 and 'are approximately horizontal when the cam-slides 64 and are at the limit of their downward movement. Upon its downward movement the cam-slide 64, acting through its arm 68, link 70, and rock-arm 72, will reciprocate its corresponding under looper 46 imparting thereto its rearward or return stroke. Similarly, cam-slide 65, actin through its arm 73, link 76, and rock-arm 7 will reciprocate its corresponding upper looper 47 imparting there-- to its rearward or return stroke. Upward movement of each cam-slide imparts to its looper forward movement of the latter. The parts are so timed that when the needle is at the limit of its downward stroke the under looper 46 will be positioned at'rest at the beginning of its forward or loop-penetrating movement. In this position of said under looper its beak 54' is located slightly to the left of the'needle and in the space 27 which is between the front feed dogs 22 and the rear feed dogs 23 and on the right of the feed bar proper, as shown in Figs. 5, 6 and 6". As will thus appear, in this position the beak 54 of the under looper 46 is disposed wholly above the plane of theunder surface of the main feed bar and at one side thereof. This condition is brought about by shortening the travel ofthe under looper and by giving it ,an extended period of dwell at each end of each reciprocating stroke thereof. The maintaining of the beak 54 of the under looper 46 at one side of the feed bar proper makes it possible to so construct that bar as to avoid removal of any of the metal thereof to form a passage to accommodate the movement of the under looper.

According to the present invention, each looper at each end of each stroke in the reciprocation thereof, is given a relatively extended period of rest or dwell and the periods of dwell at the ends of each stroke are of substantially equal duration. The term extended period of rest or dwell is well understood in the sewing machine art as meaning that period of dwell which is of longer du- 45 surface ration than the momentary period of dwell given to a reciprocating looper through the medium of a driving eccentric. Furthermore, according to this invention each roomrocating stroke is at a gradually and increasing or accelerating speed followed by a gradually decreasing or retarding speed. Thus in its forward stroke of reciprocation each looper moves with gradually accelerating speed followed by a gradually decreased or retarded speed until the looper comes to rest for an extended period of dwell before the next succeeding or backward stroke. Said backward stroke follows the same speed variation as in the forward stroke, bringing the looper to rest for another extended period of dwell before the next succeeding forward stroke and so on. In the construction illustrated the

loopers

46 and 47 are actuated and 2 t'eciprocated in the manner aforesaid by their respective earns 62 and 63, with the results, among others, of minimizing or practically eliminating overflow of the loopers and shocks and vibrations incidentto the starting and stopping of each looper for each reciprocating stroke thereof.

As the

cams

62 and 63 are identical in construction, a description of one will apply to both. Referring particularly to Fig. 6, cam

63 is of the peripheral type about a center or axis at a and includes in its peripheral surface two oppositely disposed concentric portions 78 and 79, the former on a larger radius than the latter; and two oppositely disposed eccentric portions 80 and 81, each of said four portions covering ninety degrees of said surface and each eccentric portion merging with the concentric portions between which it is interposed. Furthermore, each of the concentric surface portions is disposed equally at opposite sides of the major axis of the cam and each of the eccentric surface portions is disposed equally at opposite sides of the minor axis of the cam. The eccentric portions 80 and 81 are of identical formation but are in reversed position; that is, in following around the cam in clockwise direction, the surface portion 81 will first be reached at its high end, whereas the surface portion 80 will first be reached at its low end. In reciprocating its camslide 65 the peripheral surface of the cam 63 rotates between and in contact with top and bottom inside parallel surfaces w and y of the upper frame-like end of the slide 67, as best shown in Fig. 6. It follows that while one eccentric surface portion 80 or 81 is coacting with one of said parallel surfaces the other eccentric surface will be simultaneously coact-.

c0 ing with the other parallel surface; and the same also applies with respect to concentric surface portions 78 and 79 and said parallel surfaces of the cam-slide. The eccentric surface portions 80 and 8, are each formed on a .curve which gives to the associated ment will enter the same,

looper an increasing velocity from the beginning of each stroke followed by a decreasmg or retarding velocity during the latter part of the stroke.

Following each forward stroke of a looper it remains at rest or has an extended period of dwell while the concentric surface portions 78 and 79 are cooperating with the parallel surfaces of the cam-slide. The looper is then moved backwardly and this is followed by another similar period of rest or extended dwell. Thus for each complete rotation of its cam, or cycle of operation, each looper has two periods of movement with two intervening periods of rest or extended dwell, all four periods being of equal duration.

The movements imparted to the loopers and the functioning thereof in connection witheach other and with the needle in the formation of stitches will readily appear by reference to Figs. 11 and 14 inclusive. The work or fabric W is intermittently fed past the needle 9 by the feeding mechanism previously described, and the edge of the work is trimmed" by the trimming mechanism at a point in advance of the needle. The needle 9 carries a needle thread X, the under looper 46 carries-a thread Y, and the upper looper 47 carries" a thread Z. The parts are so timed that .when, as shown in Fig. 11, the needle is at the extreme lower end of its down stroke, the under looper 46 will be at rest preparatory to beginning its forward or looping-taking movement, and the upper looper 47 is about to begin its rest preparatory to beginning its u ward or forward movement over the edge of the work, and as the needle 9 begins to rise it throws out a needle thread loop X in rear of the needle, and simultaneously with the rise of the needle the under looper 46 begins its forward travel, the beak 54 thereof entering said needle thread 1001). The under looper 46 moves to the right and into a position above the upper looper 47, while the lat ter still remains in its extended period of rest. Thus as shown in Fig. 12 of the drawings, the needle has made part of its upward stroke, the under looper has made its full forward movement to a position of extended 'dwell or rest for cooperation with the upper looper, and the upper looper is still at rest in the same position as in Fig. 11. Before the needle 9 reaches the upper end of its stroke the upper looper 47 begins its forward or upward movement. The beak 58 passes upwardly in rear of the beak 54 of the under looper and enters the loop Y formed bv the \under looper. The ripper looper 47 thus forms a loop Z in its thread Z. The upper looper continues to move upwardly over the edge of the fabric until said loop Z is ositioned directly in the path of the nee le 9 so that the latter in the next downward movethe upper looper partaking of an extended period of dwell at the upper end of its travel so as to insure the needle entering said loop Z Thus, as shown in Fig. 13, the needle has moved to the limit of its upward'stroke, the upper looper has about completedv its forward stroke and then stands in a state of extended dwell or rest in position for cooperation with the needle. The lower looper is still in a state of rest or dwell as the needle reaches the upper end of its stroke as in Fig. 12, and the work has been fed rearwardly approximately one-half the length of the stitch. As the needle 9 begins to descend the under looper 46 is given its return movement, the under looper reaching the end of its return movement by the time the point of the needle has gotten well into the work, as shown in Fig. 14. The under looper has made its rearward or return stroke to a state of extended rest or dwell and has shed the needle loop through which it'was previously engaged. The upper looper still remains in the state of extended rest or dwell at the limit of its forward stroke, and the continued feeding of the work has carried said work rearwardly the full length of the stitch to a state of rest before being entered by the int of the needle. Thus the needle thread oop X which was around the under looper was shed from said under looper at the time the point of the needle is adjacent the fabric. This timi insures the latter half of the down stroke of tl ie needle being utilized in pulling up the shed needle thread loop and in setting the stitch. During the latter half of the down stroke of the needle the upper looper 47 is returned to its initial position, the upper looper shedding the looper thread loop Y before the needle reaches the lower end of its stroke.

The improved thread control means and the operation thereof will now be described.

The needle thread X is led from the source of supply through a guide-eye 82 into a tension 82, thence through a guide-eye 83, thence thrdugh a tension 84, thence through a guideeye 85, thence'through a guide-eye 86, and thence through a guide-eye 87 formed in the overhanging arm 88 carried by the post 37, as-

shown in Figs. 1, 3 and 6, and thence to the needle eye. The

tensions

82 and 84 are disposed in rear of the needle lever 11 and the guide-

eyes

85 and 86 are likewise disposed in fear of the.needle lever and on opposite sides of a thread nipper 89, the guide-eye 86 being formed in a cloth deflector plate 90. The thread nipper 89 comprises an arcuate bar 91 which extends parallel to the line of feed and between the guide-

eyes

85 and 86, the upper surface of the bar 91 having an upwardly extending cam 92, and a flat spring 93 which is fixed at its front end to. the arm 91, extends longitudinally of the arm 91 above the cam 92 and normally in contact with the high point of said cam. The needle thread X nor- I mally passes between the cam surface and the ed rocker arm 96 and an eccentric strap or link 97 which cooperates with an eccentric 98 fixed to the main shaft 13. Thus the finger 94 is reciprocated back and forth along the nipper arm 91 from a point in front ofthe cam 92 to a point in rear thereof. The eccentric 98 is so timed relative to the needle lever eccentric 14 as to cause the finger 94 to move against the needle thread, which extends across the nipper arm, and pullofi' suflicient thread from the supply for use in the forming of the next stitch and also take up the needle thread during the first part of the backward stroke of the under looper 46. The needle thread-loop X which is around the under looper is thereby gradually shortened during the return stroke of said under looper and during the first part of the down stroke of the needle. When the needle thread-loop X has been shed from the under looper 46, the finger 94 ceases to function as a take-up At this point in the cycle the needle point is adjacent the work andconsequently the entire last half of the downward stroke of the needle is utilized in pulling up the previously formed needle thread-loop X and thereby firmly setting the stitch.

In the specific operation, as the needle begins to rise, the finger 94 is moved forwardly to the end of its stroke and before the needle point leaves the work the finger 94 is moved rearwardly. Simultaneously with the needle reaching the high point of its travel the finger 94 contacts with that portion of the needle thread which extends across the nipper, and during the first half of thedownward movement of the needle or until the point of the needle is adjacent the work, the finger 94 moves rearwardly against said needle thread pulling thread from the supply and simultaneously taking up the slack in the 'needle thread due" to the backward movement of the under looper as previously described. That portion of the-needle thread which extends across the nipper is thus moved to a point 1n rear of the nipper cam 92. As the .needle beins the last half of its downward stroke, the finger 94 begins to move forwardly in unison "with the downward movement of the needle,

radually releasing the needle thread thereby e continued down stroke of the needuring't ,dle whereby that portion of the needle thread position, the needle thread is impinged or nipped by the cam 92 and the nipper spring 93. This nipping action is sufiic1ent to pre vent the needle thread being pulled from the supply while the previously formed stitch is receiving its final setting by the last part of the last half of the downward movement of the needle. In other words, the first half of the down stroke of the needle shortens up the needle thread loop, which is around the under looper 46 duringthe time the under looper is backing out of said loop, and then after the under looper has shed the needle thread loop, the second half of the down stroke of the needle is utilized in pulling up said needle thread loop to the under side of the work and in setting the stitch. As the needle begins its upward movement the under looper 46 enters the needle thread loop, and the continued forward movement of the looper, due to the needle 1 thread loop being therearound, necessarily places tensionon the needle thread and causes the latter to move forwardly on the thread nipper cam 92 and into position tobe subsequently engaged by the thread finger 94.

The under looper thread Y is led from the supply through a tension 99, thence through and Z I have or major axis than the other.

two thread-guides 100, thence through a pair of aligned thread-

guides

101 and 102 formed in spaced

arms

103 and 104 respectively of a bracket 105, the bracket being mounted on the work-plate 6. The thread Y thence extends through a groove 106 formed in the upper face of the work-plate 6, and thence into the under looper 46, the thread passing under a bridge-piece 107 which is formed by the needle-plate 17- and which crosses the groove 106 adjacent the loopers.

The looper thread Z is led from the supply through a tension 108, thence through two thread-guides 109 to a pair of aligned thread guides 110 and 111 which are respectively formed in the

arms

103 and 104 of the bracket 105, and thence through the groove 106, and under the bridge 107 to the upper looper 47 In order to control the looper threads Y provided a vertically reciprocatory thread-finger 112 which operates between the

arms

103 and 104 of the bracket 105. The thread-finger 112 is formed with two thread-

guides

113 and 114 through which the respective threads Y and Z pass. Both of these openings are vertically elongated, the opening 114 however having a greater length The threadfinger 112 is attached to a lever 115 which is fulcrumed on the countershaft 12, and this lever is reciprocated by means of an eccentric 116 mounted on the main shaft 13. r I The thread-finger 112 moves upwardly simultaneously with the forward movement of the under looper 46 to take up the looper thread Y and thereby prevent the needle thread loop which surrounds the beak 54 of said under looper from whipping the threadloop Y under the point of the looper. While the under looper 46 is occupying its position of extended dwell at the forward end of its stroke, the upper looper .47 moves upwardly through the thread-loop Y, and at this time the thread-finger 112 begins its downward movement to give slack to the looper. thread Y so as to permit the upper looper 47 to enter said looper thread loop- Y with perfect freedom. As the under looper 46 begins its return movement the looper thread Y is further slackened by the continued downward movement of the finger 112so as to avoid breaking the thread forming the loop Y which is around the upper looper. The thread Y becomes taut owing to the slack being removed by reason of the continued backward movement of said under looper. The last extreme part of the backward movement of the under ooper serves to pull the thread Y from the supply, the stationary thread-

guides

101 and 102 and the movable thread-guide 113 being in alignment. Immediately following the under looper reaching the end of its backward stroke, and while the needle is completing the last half of its down stroke and pulling up the previously formed needle threadloop X, the thread-finger 112 is moving upwardly to take up the slack in the looperthread Y.

When the upper looper is in the upper or forward position of its travel the stationary thread-guides 110 and 111 and the movable thread-guide 114 are in alignment. Simultaneously with the backward movement of the upper looper 47 the thread-finger 112 moves upwardly, but owing to the elongated vertical opening 114 no take-up action is imparted to the thread Z until the thread is engaged by the bottom of said opening 114 at which time the upper looper is substantially at the lower or rear end of its stroke. Consequently the needle enters the looper thread-loop Z while the latter is free from tension and the takeup action on the looper-thread Z does not occur untilafter the needle thread-loop X has been set. Therefore, as shown in Fig. 14, the upper looper thread of the loop Z which extends rearwardly from the eye of the upper looper is slack at the time the needle is entering said loop, and inasmuch as the needle thread is taut at this time there will be no strain imparted to the looper-thread Z by the needle thread when crossing the former and while the needle is entering the looper-thread loop Z. Thus the looper-thread Z is slack at the time the needle thread loop X is being 'pulled up to the underside of the work and upward movement of the thread-finger 112 serves first to take up the slack of the thread Z which is embodiedin the previously formed stitch, and then functions to pull thread from the supply. The thread-finger 112 then moves downwardly and the upper looper 47 moves forwardly or upwardly, the downward movement of the finger 112 serving to give slack to the thread Z so as to permit the upper looper 47 to move forwardly and up-,

g shed from the under looper at the earliest possible moment in each cycle; the time of so shedding the needle thread-loop-results, in

conjunction with the thread control mechanisms, in the production of very tight stitches and the standard Willcox & Gibbs two-thread overlook machine can be readily converted into a three-thread overlook machine by substituting a small number of parts.

What is claimed as new is:

1. In a sewingmachine, a stitch forming mechanism including a vertically reciprocatory needle, a looper cooperating therewith and fulcrumed on a horizontal pivot, and means for reciprocating said looper including a cam, a vertically reciprocatory frame ac-v tuated by said cam, means for guiding said frame in a straightline during its reciprocation, and a link connecting said looper and said frame. p

2. In a sewing machine, a stitch forming mechanism including a vertically reciprocatory needle, a looper cooperatin therewith and fulcrumed on a horizontal pivot, a horizontal rotary shaft disposed in rear of the looper, a cam fixed to said shaft, a vertically reciprocatory frame actuated by said cam, means for guiding said frame in a straight line durin its reciprocation, and a link connecting said looper and said frame.

3. In a sewing machine, a stitch forming mechanism including a vertically reciproca tory needle, a looper cooperating therewith, a bracket on which the looper is fulcrumed, a horizontal rotary shaft disposed in rear of thelooper, a cam fixed to said shaft, said bracket having a vertical guideway, a vertically reciprocatoryjrame actuated by said cam and having a portion operatin in said guideway, and a link connecting said looper and said frame.

4. In a sewing machine, the combination ated by said cam, and a link connecting the V looper and the frame.

5. In a sewing machine, the combination with a bed plate, of a work plate mounted thereon and provided with a needle opening, a reciprocatory needle movable into and out of said opening, a main shaft journaled on said work plate, a hanger depending from the work plate and provided with a verticalguideway, a looper pivoted on the hanger at one side of the needle opening for cooperation with said needle, and means for drivingthe looper comprising a cam fixed to said shaft, a vertically reciprocatory frame actuated by said cam and slidable in said guideway, and a link connecting the looper and the frame.

6. In a sewing machine, the combination with a bed plate, of a work plate mounted thereon and-provided with a needle opening, a reciprocatory needle movable into and out of said opening, a main shaft journaled on said work plate, a U-shaped hanger depending from and connected to the work plate on opposite sides of the needle opening, said han er being centrally formed with a vertical gui eway, a looper pivoted on the hanger at. one side thereof and at one side of the needle opening for cooperation with the needle, and means for driving the looper comprising a cam fixed to said shaft, a vertically reciprocatory frame actuated by said cam and slidable in said guideway, and a link connecting the l'ooper and the frame.

' 7. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, means for reciprocating the under looper a d for giving an extended period of dwell thereto at each end of each reciprocating stroke, the periods of dwell and of activity being of substantially equal duration, and means for reciprocating the upper looper in timed re lation with the under looper and the needle.

8. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the underlooper at the 'side of the work and with the needle above the work, a horizontal rotary shaft disposed in rear, of the loopers,

means for reciprocating the under looper ineluding a cam fixed on said shaft, the cam having opposite concentric cam portions and opposite eccentric cam portions respectively arranged intermediate said concentric portions for transmitting to the under looper alternate periods of extended dwell and of activity, said periods being of like duration, and means for reciprocating the upper looper in'timed relation with the under looper and needle.

9. In an overedgesewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, means for reciprocating the upper looper and for giving an extended period of dwell thereto at each end of each reciprocating stroke, the periods of dwell being of substantially equal duration, and means for reciprocating the under looper in timed relation with the upper looper and the needle.

10. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle belowt-he work, a

reciprocatory upper looper cooperating with i the under looper at the side of the work and with the needle above the work, means for reciprocating the upper looper and for giving an extended period of dwell thereto at each end of each reciprocating stroke, said means transmitting to the upper .looper in succession a gradually increased speed and a gradually decreased speed during each reciprocating stroke thereof, and means for reciprocating the under looper in timed relation with theupper looper and the needle.

11. In anoveredge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, :1 reciprocatory under looper co; operating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, means for reciprocating the upper looper and for giving an extended period of dwell thereto at eac end of each reciprocating stroke, said means transmitting to the upper looper in succes-' reci rocato u er loo er cooperating with the iinder liib pe at the side of the work and with the needle above the work, means for reciprocating the upper looper and for giving an extended period of dwell thereto at each end of each reciprocating stroke, the periods of dwell and of activity being of substantially equal duration, and means for reciprocating the under looper in timed relation with the upper looper and the needle.

13. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, means for reciprocating the upper looper and for giving an extended period of dwell thereto at each end of each reciprocating stroke, said means transmitting to the upper looper in succession a gradually increased speed and a gradually decreased speed during each reciprocating stroke thereof, the periods of dwell and of activity being of substantially equal duration, and" means for reciprocating the under looper in timed relation with the upper looper and the needle.

14. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, means for reciprocating the .upper looper and' for giving an extended period of dwell thereto at each end of each reciprocating stroke, said means transmitting to the upper looper in succession a gradually increased speed and a gradually decreased speed during each reciprocating stroke thereof, the eriods of dwell and of activity being of su stantially equal duration, and the periods of increased speed and of decreased speed being of substantially equal duration, and means for reciprocating the under looper in timed relation with the upperlooper and the needle.

15. In an overedge sewing machine, a

stitch forming mechanism comprising a reciprocatory needle, 9. reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of thework and with the needle above the work, a horizontal rotary shaft disposed in rear of the loopers, means for reciprocating the upper looper including a cam fixed on said shaft, the cam having opposite concentric cam portions and opposite eccentric cam portions respectively arranged intermediate said concentric portions for transmitting to the upper looper alternate periods of extended dwell and of activity, and means for reciprocating the under looper in timed relation with the upper looper and needle.

- 16. In an overedge sewing 'machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the Work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, a horizontal rotary shaft disposed in rear of the loopers, means for reciprocating the upper looper including a cam fixed on said shaft, the cam having opposite concentric cam portions and opposite eccentric cam portions respectively arranged intermediate said concentric portions for transmitting to the upper looper alternate periods of extended dwell and of activity, said periods being of like duration, and means for reciprocating the under looper in timed relation with the upper looper and needle.

17. In an overedge sewing machine, a stitch forming mechanism comprising a recipratory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, a horizontal rotary shaft disposed in rear of the loopers, means for reciprocating the upper looper including a cam fixed on said shaft, the cam having opposite concentric cam portions and opposite eccentric cam portions respectively arranged intermediate said concentric portions for transmitting to the upper looper alternate periods of extended dwell and of activity, said periods being of likeduration,

the eccentric portions being shaped to transmit to the upper looper in succession a gradually increased speed and a gradually decreased speed duri'ng each reciprocating stroke of said looper, and means for reciproeating the under looper in timed relation with the upper looper and needle.

' 18.. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with theneedle above the work, a horizontal rotary shaft disposed in rear of the loopers,means for reciprocating the upper looper including a cam fixed on said shaft,the

cam having opposite concentric cam portions and opposite eccentric cam portions respectively arranged intermediate said concentric portions for transmitting to the upper looper alternateperiods of extended dwell and of activity, said periods being of like duration, the eccentric portions being shaped to transmit to the upper looper in succession a gradually increased speed and a gradually decreased speed during each reciprocating stroke of said looper, the periods of increased speed and of decreased speed being of substantially equal duration, and means for reciprocating the under looper in timed relation with the upper looper and needle.

19. In an overcdge sewing machine, a stitch forming mechanism comprising a re ciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, and means for reciprocating said loopers and for imparting an extended dwell to each looper at each end of each reciprocating stroke.

20. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, and means for reciprocating said-loopers and for imparting an extended dwell to each looper at each end of each reciprocating stroke, said means transmitting to each looper in succession a gradually increased speed and a gradually decreased speed during each reciprocating stroke thereof.

21. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper cooperating with the needle below the work, a reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, and means for reciprocating said loopers and for imparting an extended dwell to each looper at each end of each reciprocating stroke, said means transmitting to each looper in sucession a gradually increased speed and a gradually decreased speed during each reciprocating stroke thereof, the periods of dwell and of activity being of substantially equal duration, and the periods of increased speed and of decreased speed being of substantially equal duration. a

. 22. In an overedge sewing machine, a stitch forming mechanism comprising a reciprocatory needle, a reciprocatory under looper 00- operating with the needle below the work, a

reciprocatory upper looper cooperating with the under looper at the side of the work and with the needle above the work, and means 'for reciprocating said loopers including a