US3658021A

US3658021A - Arrangement for cutting threads on double stitch sewing machines

Info

Publication number: US3658021A
Application number: US62574A
Authority: US
Inventors: Kristen Hedegaard; Anton Lessmeister
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1969-08-16
Filing date: 1970-08-10
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25
Also published as: GB1280070A; DE1941681A1

Abstract

Thread cutting device for double stitch sewing machines having a looper turning in a horizontal plane, a bobbin housing secured against turning movements by means of a retaining finger resting against an abutment in the stitch plate, an outlet opening for the looper thread determining the course of the looper thread between stitch plate and bobbin housing and a thread catcher having a point cooperating with a cutter and movable in a horizontal plane where the outlet for the looper thread is disposed below the plane of the surface of the bobbin housing at its wall facing the needle, preferably in the area of the retaining finger, and the point of the thread catcher is movable below the plane of the surface of the bobbin housing between the path of movement of the needle and the retaining finger of the bobbin housing.

Description

United States Patent ns1 3,658,021 Hedegaard et al. [451 Apr. 25, 1972 [541 ARRANGEMENT FOR CUTTING 2,866,425 'i2/195s Paimbacn ..112/-184 X THREADS 0N DOUBLE STITCH 2,163,994 6/1939 Fischer ..112/ 252 3,21 1,117 lO/l965I Speichermann et all. ..112/252 [72] Inventors: Kristen Hedegaard, Gentofte, Denmark; Anton Lessmeister, Hutschenhausen, Ger many [73] Assignee; Firma (l. M. Pfaff/11., Kaiserslautern am ll'nlz. (iermnny [22] Filed: Aug. l0, 1970 [21] Appl. No.: 62,574

[30] Foreign Application Priority Data Aug. 16, 1969 Germany ..1 19 41 681.0

[52] U.S.Cl ..112/252 [5 l] Int. Cl. t D05b 65/02 [58] Field of Search ..1 12/252 [56] References Cited UNITED STATES PATENTS 3,503,355 3/1970 Hagemeyer et al. ..112/252 Primary Examiner-James R. Boler Attorney-Robert H. Jacob [5 47] ABSTRACT Thread cutting device for double stitch sewing machines having a looper turning in a horizontal plane.. a bobbinhousing secured against turning movements by means of a retaining fingerresting against an abutment in the stitch plate, an outlet opening for the looper thread determining; the course of the looper thread between stitch plate and bobbin housing and a thread catcher having a point cooperating with a cutter and movable ina horizontal plane where the outlet for the looper thread is disposed below the plane of the surface of the bobbin housing at its wall facing the needle, preferably in the area of the retaining finger, and the point of the thread catcher is movable below the plane of the surface of the bobbin housing between the path of movement of the needle and the retaining fingerof the bobbin housing.

S Claims, 10 Drawing Figures PATENTEUAPR 2 5 is?? SHEET 3 UF 3 BACKGROUND OF THE INVENTION The invention relates to thread cutting devices for sewing machines. More in particular, the invention concerns a thread cutting arrangement for double stitch sewing machines having a looper or catcher that rotates in a horizontal plane, a bobbin housing mounted in the looper against rotary movements secured by means of a retaining finger that rests against an abutment on the stitch plate, with an outlet for the looper thread that determines the course of the looper thread between the stitch plate and the bobbin housing, and a thread catcher movable in a horizontal plane that cooperates with a cutter, with a catcher point and a recess formed thereon for receiving the needle and the looper thread.

ln a known thread cutting device a thread catcher that is movable above the bobbin housing surface is provided which is pivotally movable about an axis that is disposed generally parallel to the looper shaft. The point of the thread catcher is offset rectangularly and provided with a V-shaped incision where the two legs of the thread catcher defined by the incision are moved in an essentially vertical plane between the bobbin housing and the retaining finger that extends laterally and upwardly from its housing surface and seize the needle thread, as well as the looper thread during the first part of the thread catcher movement. The two threads seized are disposed during the further course of the thread catcher movement in front of an aperture that extends from the intersection ofthe two legs ofthe Vshaped incision and are guided and severed by a cutter entering this aperture. The arrangement of the two legs is such that the upper leg of the thread catcher moves above the plane of the bobbin housing surface and the lower leg below the plane ofthe bobbin housing surface. ln this manner, it is insured that during the thread catching movement of the thread catcher, the thread that leaves the aperture at the top side of the bobbin housing and leads from there to the stitch hole, as well as also the part of the needle thread loop that rests during the guiding of the needle thread around the bobbin housing on its upper side is seized. The part of the needle thread loop that is moved during the guiding of the needle thread about the bobbin housing over its upper side is with loopers of this type of construction always the thread supply leading to the needle thread loop so that this thread catcher seizes and cuts the looper thread and the part of the needle thread loop that leads to the thread supply. The part of the needle thread loop leading to the sewing material extends during the thread catching movement of the thread catcher along the lowerpart of the bobbin housing and thence below the bobbin housing stop finger between the surface of the bobbin housing and the inside of the looper body to the stitch hole and cannot be seized by the thread catcher that moves along a path of movement extending between the retaining finger and the housing surface of the bobbin housing. With the older arrangement the threads are severed almost centrally at their seizing location by the cutter that dips into the aperture of the thread catcher so that the part of the needle thread loop leading to the material is at least as long as the part that extends to the thread supply. Since the end of the needle thread that remains with thethread supply must be of a length that insures the forming of the starting stitches ofthe next following sewing cycle, there results an undesired length for the needle thread end remaining on the sewing material due to the almost central separation of the needle thread loop which for certain sewing operations requires a shortening of the needle thread end that must be effected manually. Beyond that, the thread catcher that moves above the upper surface of the bobbin housing makes it necessary to place the looper lower which is not advantageous due to the displacement ofthe thrust ofthe needle movement for reasons ofsewing technique.

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a thread cutting means for double step stitch sewing machines having a looper that rotates in a horizontal plane which makes it possible to seize the part of the needle thread loop leading to the material and the looper thread by means of only one thread catcher that does not influence the level or height of the looper.

ln order to accomplish this, the invention is based on the technical problem to so constitute the course of the looper thread from the bobbin housing to the stitch hole, while insuring flawless stitch formation, that the looper thread together with the part of the needle thread loop leading to the sewing material can be seized with a thread catcher that moves laterally of the bobbin housing.

This problem is solved in accordance with the invention in that the aperture for the looper thread is arranged below the plane of the surface of the bobbin housing at the part of its casing surface facing the needle, preferably in the area of the retaining finger, and the point of the thread catcher is movable below the plane of the surface of the bobbin housing between the path of movement of the needle and the retaining finger of the bobbin housing.

With double stitch loopers of the type referred to above, the looper thread is guided from the bobbin disposed in the bobbin housing through a slot that is usually directed obliquely upwardly in the housing surface of the upper part of the looper housing below its tensioning spring through to an outlet opening provided on the surface of the bobbin housing in the area of the abutment lug for the bobbin housing vent and from there extends obliquely upwardly to the stitch hole.

With the former looper construction, the looper thread extends from its outlet opening practically in the same plane as the part of the needle thread loop that moves during guidance of the needle thread around the bobbin housing over its surface to the thread supply. With the arrangement of the aperture for the looper thread in accordance with the invention, the looper thread leads from its aperture provided at its part of its housing surface facing the needle below the plane of the bobbin housing surface between the housing surface of the bobbin housing and the inner wall of the looper body through to the stitch hole, thus, it extends to tlhe stitch hole below the plane of the bobbin housing surface and thus also below the part of the needle thread loop that is to be moved by the looper below the plane of the bobbin housing surface to the thread supply. If in this connection the looper thread outlet opening is arranged in the region of the retaining finger of the looper housing closely above its bearing rib, then the looper thread emerging from its opening extends during the period of greatest loop expansion of the needle thread nearly parallel to its part leading to the sewing material and is seizable in its region disposed between the stitch hole and the retaining finger of the bobbin housing together with the part of the needle thread loop that leads to the sewing material. lf due to displacement of the retaining finger toward the center of the bobbin housing between the path of movement of the needle and the retaining finger of the bobbin housing a passage space is provided for a thread catcher, the thread catcher which moves below the plane of the bobbin housing extending along a path of movement in a straight line or arcuately in a horizontal plane between the retaining finger of the bobbin housing and the path of movement of the needle may seize the looper thread as well as the part of the needle thread loop goingto the material being sewn. In this manner assurance is given that on the one hand the thread catcher does not seize the part of the needle thread loop leading to the thread supply, and on the other hand the looper thread thus formed can during the normal sewing operation neither be seized by the point of the looper that seizes the needle thread, nor by the horn controlling the loop dropping movement of the needle thread` ln order to make the thread ends remaining on the sewing material short and the ends remaining on the thread supply optimally long, it is necessary to displace the cutting location of both threads from their location of seizure at the thread catcher in the direction of the stitch hole. An advantageous solution of this problem is obtained in that the thread catcher has a recess, known per se, extending in the direction of its point with a terminal edge forming the counter cutter for the cutter and above the thread catcher a thread guide with a thread guiding surface is arranged which during the pull-out movement of the thread catcher moves above its recess along a path of movement parallel to its path of movement oppositely to the thread catcher. If already one thread catcher with a thread guide surface arranged in a fixed position would insure that the threads to be cut that extend from their point of seizure on the thread catcher obliquely upwardly come to rest in the recess, then the thread guide surface of the thread guide that moves opposite to the thread catcher affords in addition the security that the threads are not clamped between the thread catcher and the thread guide, and are not squeezed off at a location that is not predetermined.

In order to obtain extremely short thread ends, the cutter is arranged in accordance with a further development of the invention between `thread guide and the thread catcher and movable during the withdrawing movement of the thread catcher upon a course of movement extending parallel thereto. In this manner it is possible to sever the threads closely below the stitch hole so that the thread ends remaining on the sewing material are only of a length that corresponds essentially to the thickness of the stitch plate and to the vertical difference between the bottom side and the top side of the thread catcher.

An arrangement of thread catcher, thread guide and cutter which is structurally simple and space saving, which simultaneously provides the opportunity of driving the parts moving oppositely to one another by means of a single rocking shaft, while interconnecting only two drawbars is obtained, in that thread catcher, thread guide and cutter are arranged coaxially to one another and movable along paths of movement that extend eccentrically to the looper.

In the arrangement in accordance with the invention of the aperture for the looper thread provided in the looper housing, care must be taken in addition besides the correct looper thread course that the bobbin with the looper thread supply can be readily inserted into the upper part of the looper housing and can he inserted in the looper housing bottom part in as completely threaded condition as possible. This requirement is met in accordance with a further feature of the invention that the bobbin housing bottom is provided laterally of the retaining finger with a recess that reaches up to its bearing rib and the looper housing top has a bridge that extends into this recess on whose lower end the aperture forming the looper thread guide for the looper thread is formed.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is described more in detail with reference to an embodiment illustrated in the drawings in which FIG. l is a front view ofa sewing machine,

FIG. 2 is a perspective illustration of the thread cutting arrangement and ofits drive mechanism,

FIG. 3 is a perspective exploded view of the individual parts ofthe thread cutting device,

FIG. 4 is a perspective illustration ofa first embodiment ofa bobbin housing,

FIG. 5 is a perspective illustration of a second embodiment ofa bobbin housing,

FIG. 6 is a plan view of a part of the bottom of the housing in accordance with FIG. 5,

FIG. 7 is a section through a looper with the bobbin housing in accordance with FIG. 4,

FIG. 8 is a perspective illustration of the thread cutting device shortly before the threads are seized,

device during the withdrawing movement, and

DESCRIPTION OF THE INVENTION The standard 2 of the sewing machine is mounted on the base plate l (FIG. l) on which the horizontal arm 3 is formed that has head 4 at its end. In the arm 3 the armshaft S is journalled which is in driving connection with the needle bar 7 that carries thread guiding needle 6 which moves up and down in the head 4. In the head of the sewing machine there is furthermore mounted the take-up lever 8 for the thread that cooperates with the needle in a known manner. Upon the armshaft 5 a belt wheel 9 is secured which transmits by way of a belt l0 and a wheel 11 the driving movements of the armshaft to the looper drive shaft 12 journalled in the base plate l. The looper drive shaft 12 supports a pinion 13 which meshes with a cooperating pinion 15 disposed upon a vertical looper shaft 14 and thus drives the double stitch looper 16 which is mounted at the upper end ofthe looper shaft I4 and rotates in a horizontal plane.

The double stitch looper 16 (FIG. 7) has a looper body I7 on which a looper point 18 is formed. ln the double stitch looper 16 a bobbin housing 21 is journalled which is defined by a bobbin housing bottom portion 19 and a bobbin housing upper portion 20, and which has a retaining finger 22 at its surface that faces the needle 6, which finger rests against an abutment 23 of the stitch plate 24 and secures the bobbin housing 2l against rotary movements. The lower part I9 of the bobbin housing has a bearing rib 25 which engages a guide groove 28 formed by the looper body 17 and the cover segment 27 that carries the looper horn 26. Furthermore, a side wall 29 is provided on the lower part 19 of the looper housing which supports at its upper end an abutment lug 30 for the housing member 31. The upper part 20 of the bobbin housing has a slot 33 along its side wall 32 (FIG. 4) that extends obliquely upwardly and which ends below a tensioning spring 34 for the looper thread in a bore 35 provided in the side wall 32. In the embodiment illustrated in FIG. 4 of the bobbin housing 21, the lside wall 29 ofthe lower part 19 ofthe housing is provided with a recess 36 between the stop finger 22 and the abutment 30 for the housing member 3l into which projects a downwardly extending bridge 37 that extends closely above the bearing rib 25 that is provided on the upper part 20 of the bobbin housing. This bridge has an outlet opening 38 for the bobbin thread in the area of its lower end. The looper thread received by the bobbin 39 arranged in the bobbin housing 21 is guided from the bobbin through the obliquely upwardly extending slot 33, respectively the bore 35 of the upper part 20 of the bobbin housing, and from there below the tension spring 34 to a thread guide 40 provided onthe upper part of the bobbin housing, and thence behind the side wall 29 of the lower part 19 ofthe bobbin housing to the looper thread outlet opening 38 formed on the bridge 37 of the upper part of the bobbin housing and from there extends in the manner reflected by FIGS. 4 and 7 between the inner wall of the looper body 17 and the bobbin housing 21 through to the stitch hole 41 in the stitch plate 24.

In the second embodiment of a looper housing illustrated in FIGS. 5 and 6, it is likewise formed by the lower part 119 of the bobbin housing and an upper part ofthe bobbin housing and has a retaining finger 122 at its wall surface facing the needle 6 which rests against an abutment 23 of the stitch plate 24 and thus secures the bobbin housing 121 against rotating. The lower part 119 of the bobbin housing 129 is likewise provided with a bearing rib 125 that engages a guiding groove 28 formed by the looper body 17 and the cover segment 27 that supports the looper horn 26 which is fastened thereto. On the lower part 119 of the looper housing a side wall 129 is also provided which at its upper end supports an abutment lug for the housing member 31. The upper part 120 of the bobbin housing has a slot 133 along its side wall 132 that extends obliquely upwardly, which terminates below a tension spring A, abutment lug 130, which terminates in the area of the side wall 129 of the bobbin housing between the` retaining finger 122 and the lug 130,and has at its end an aperture 138 forming a guide for the looper thread formed in a manner reflected by FIG. 6. The looper thread in this embodiment of the bobbin housing extends l from the bobbin 139 disposed therein through the slot 133, respectively the bore 135, below the tension spring 134 to the thread guide 140 arranged at its end,

vand thence alonglthe lower side of the rib 137 to the aperture 138 defined at the end thereof and leading from there between the inner wall of the loope'rbody 17 and the bobbin housing 121 in a manner illustrated'by FIG. 5, obliquely upwardly to the stitch hole 41 of the stitch plate 24.

At the bottom side of the base plate 1, a supporting plate 45 (FIG. 2) is secured which has two

grooves

46, 47 that extend arcuately and concentric relative to each other which are eccentric withrespectto the double stitch looper 16. The lower groove 46 that is disposed in a horizontal plane serves as a guide path for a thread catcher 48 that is provided therein, whose point 49 swings below the plane of the surface of the

bobbin housing

21, 121 in a path of movement which extends between the-'retaining finger 22,122 and the stitch hole 4l of the stitch plate 24. The thread catcher 48 (FIG. 3) has a recess forming a counter hook S0 at its lateral surface that faces the needlel 6 which connects with a groove 51 extending in the direction ofthe point 49 and which in turn ends in a bore 52. The terminal edge of the recess 51 or the bore 52 defines a counter Vedge 53 for a cutter 54 that cooperates with the thread catcher 48. At the end remote from its point a receiving bore 55 for a stud 56 is provided on the thread catcher 48 which projects through an arcuatelyextending slot 57 of the support plate 45 arranged in the groove 46 and is received by a drawbar 58.

The cutter 54 (FIG. 3) arranged above the thread catcher 48 is likewise of arcuate shape and is received in the upper groove 47 of the support plate 45 which is wider with respect to the lower groove 46. For driving the cutter 54 which has an edge 59, it is provided with a bore60 which is engaged by a stud 6l that projects through a slot 62 which is likewise arcuately shaped and is arranged laterally of the groove 46 in the groove 471and is in its turn mounted on a drawbar 63.

Above the cutter 54 a thread guide 64 with a point 65 and a thread guide surface 66 adjacent thereto is arranged in the groove 47 which receives the same. The arrangement of the thread guiding surface 66 is of such nature that it moves during the relative opposite movements of thread catcher 48 and thread guide 64 directly above the recess 51 in the thread catcher along a path that is parallel to their path of movement. The thread guide 64 has a bore 67 for its-operation which is engaged by the stud'6l that projects into thebore 60 ofthe cutter 54.

As shown particularly in FIG. 2, a leaf spring 68 is provided upon the upper surface of the supporting plate 45 which rests upon the thread guide 64 and thereby holds the thread catcher 48, the catcher 54 and thethread guide 64 in the

grooves

46, 47 coordinated therewith. At the lower side of the support plate 45 a further leaf spring 69 is secured which serves to clamp the looper thread at the end of the withdrawing movement of the thread catcher 48 at the lower side of the support t plate 45.

For driving the thread catcher 48, respectively the cutter 54 and the thread guide 64, the two drawbars 58, respectively 63, which are engaged by the

studs

56, 61 are linked to a crank 72 in a manner shown in FIGS. 2 and 3 which is carried on rocking shaft 74 engaging a support member 73 secured to the base plate 1. At its lower end the rocking shaft is provided with a crank arm 75 whichis engaged by a drawbar 76. The free end of the drawbar 76 is connected with a bifurcated member 77, which is linked to the drawbar of an electromagnet 78, which in turn is secured to the lower side of the base plate l by means of a support member 79. Between the support member 79 and a setting ring 80 provided on the bifurcated member 77, a spring 8l is arranged which is'tensioned during the thread seizing movement of the thread catcher 48, and then controls the thread withdrawing and cutting movement of the thread catcher. It is, of course, also possible to carry out the movements of the thread catcher 48, respectively the cutter 54 and the thread guide 64| with a four-joint trans-V mission that is in releasable connection with the main shaft of the sewing machine and which engages the crank arm 75 or the drawbar 76.

The manner of operation of the thread cutting device is as follows:

At the end of the seam the sewing 'machine is briefly stopped with the needle in a predetermined position, for example with the needle in lowermost position by means of a stopmatik-motor; in thisconnection tlhe circuit of the elec-- tromagnet 78 is closed` simultaneously. The magnet pulls up and locks the crank arm 75 in clockwise direction as seen in FIG. 2. As a result, the crank 72 is thereupon likewise swung in clockwise direction about the crankshaft 74 and transfers the rocking movement by way of the drawbar 58 to the stud 56, to the thread catcher 48. The thread catcher effects a counterclockwise movement as viewed in FIG. 8 and moves in this connection as seen in the direction of sewingfrom its starting position behind the stitch-forming location in the direction of the stitch hole 41. During` this movement of the thread catcher 48, the needle 6 stitches again and the looper point 18 seizes the loop of the needle' thread. During the guiding of the needle thread loop around the bobbin housing, the looper point 18 guides the part of the needle thread loop that leads to the needle thread supply over the top of the

bobbin housing

21, 121. Shortly before the greatest expansion of the needle thread loop, the point 49 of the.` thread catcher 48 has reached the retaining

finger

22, 122 of the bobbin housing 2l, 121 and moves below the plane of the top surface of the bobbin housing between its retaining

finger

22, 122 and the path of movement of the needle 6 through into the needle thread loop. The part of the needle thread loop leading to the thread supply extends in this connection from `stitch hole 41 (FIG. 8) above the top side of the thread catcherI 48 over the top side of the

bobbin housing

21, 121 and thence to looper pointl8. The part ofthe needle thread loop that leads to the sewing material extends from the looper point 18 at the bottom of

the'bobbin housing

21, 121 i.e. between the bobbin housing. and the bottom of the looper body 17 through to the surface of the

bobbin housing

21, 121 facing the needle 6, and from there between the bobbin housing and the inner wall of the looper body 17 through along the lower side of the thread catcher 48 to the stitch hole 4l. The looper thread extends from its

aperture

38, 138 provided on its bobbin housing 2l, 121 likewise between the bobbin housing 2l, 121 and the inner wall of the looper body 17 obliquely upwardly along the lower side of the thread catcher 48 to the stitch hole 4l. The part of the needle thread loop and the looper thread leading to the material being sewn thus extend from the inner edge of the covering segment 27 below the point of the thread catcher 48 nearly parallel to one another (FIGS. 7 and 8) to the stitch hole and during the further course of the movement of the thread catcher 48 rest against the side surface that faces tli needle, while they are simultaneously pushed by this lateral` surface toward the stitch -holc 41 and are thus tensioned. During the further course of the movement of the catcher, it pushes itself so far into the needle thread loop which drops due to the further turning of the looper 16 from the bobbin housing 2l, 121 until that part that leads to the sewing material comes to rest together with the looper thread in the recess of the thread catcher 48 which forms a counter hook 50. The thread feeder 8 during this movement of the thread catcher 48, with the needle thread tension open, pulls up the needle thread loop which is dropping down from the

bobbin housing

21, 121 respectively from vthe looper. The cutter, as well as also the thread guide 64, execute a rocking movement due to their connection with the drawbar 63, respectively crank 72, which however is without influence on the seizing of the thread as also on the course of the threads to be seized and cut.

ln the returning position of the thread catcher movement, the electromagnet 78 is devoid of potential as a result of which the spring 81 which is now released takes over the drive of the thread catcher 48, cutter 54 and thread guide 64. The thread catcher 48 moves back in the direction of its initial position against its first direction of movement, and this connection as the needle thread tension is open pulls up needle thread, as well as looper thread with its counter hook 50. The'parts of needle and looper thread whichextend from the counter hook 50 to the material being sewn now come into engagement with the thread guide surface 66 of the thread guide 64 that moves oppositely to the thread catcher 48 and during the withdrawing movement of the thread catcher 48 are pressed from the recess 51 provided above the thread catcher along a thread guide surface 66 which is parallel to its path of movement into the recess and thus is held away from the edge S9 of the cutter 54 which moves in opposite direction to the thread catcher 48,

i.e. in the direction to the stitch hole 41. Thus, during the withdrawing movement of the thread catcher 48, the parts of needle and looper thread leading to the material being sewn are pressed by the thread guide surface 66 of the thread guide 64 into the recess 51 of the thread catcher, while the parts of the needle and looper thread which lead from the counter hook S of the thread `catcher 48 to the thread supply extend -along the lower side of the thread, while the part of the needle thread loop leading to the needle thread supply passes along the lower side of the thread catcher 48, and from there to the stitch hole 4l, while the part of the looper thread leading from the counter hook 50 to the looper thread supply is clamped in between the leaf spring and the support plate 45 provided between the'lower side and the support plate and leads from its clamping position below the plane of the surface of the

bobbin housing

21, 121 between its housing surface and the inner wall of the looper body 17 through to the

aperture

38, 138 provided on the bobbin housing 2l, 121.

As soon as the thread take-up lever 8 has reached the upper region of its dead point, the edge 53 provided on the thread catcher 48, as well as also the cutter 54 which moves opposite to the thread catcher has reached with its edge 59 the region of the stitch hole 41 and severs in cooperation with the edge 53 of the thread catcher 48 the needle, as well as the looper thread. Since the ends of needle and looper thread remaining on the material being sewn lead from the cutting location of both threads directly to the stitch hole 41 and from there to the material, they become optimally short, while the ends of needle and looper thread remaining with the thread supply will be ofa length insuring safe formation of the initial stitches of the next sewing cycle, due to the fact that they lead from the cutting location first within the recess l provided at the top of the thread catcher 48 to the counter hook 50 and from there along the lower side of the thread catcher tothe stitch hole 41, or by way of the thread clamp 69 to the looper exit opening 38,138.

Upon cuttig of both threads, the thread catcher 48 moves on in the directipn of its thread withdrawing movement and returns to its starting position, while the thread guide 64, as well as also the cutter 54 reverse their direction of movement due to their linkage with the stud 61 of the drawbar 63, and now moving in the same direction as the thread catcher 48 return likewise to their starting position.

Having now described our invention, what we desire to protect by letters patent is set forth in the appended claims.

l. Thread cutting arrangement for double stitch sewing machines having a looper turning in a horizontal plane, a nee dle movable re ative to said looper, a bobbin housing Journalled in the looper, a stitch plate disposed above said looper having an abutment, said housing having a retaining finger for engaging said abutment to secure the same against rotary movements and having an outlet opening for the looper thread determining the course of the looper thread between said stitch plate and said bobbin housing, a cutter below said stitch plate, a thread catcher having a catcher point movable in a horizontal plane and cooperating with said cutter and having a recess for accommodating the needle and looper threads adjacent said point, where the opening for the looper thread is disposed below the plane of the surface of the bobbin housing on the housing surface facing said needle, and adjacent the retaining finger, said point of said thread catcher being movable below the plane of the surface of the bobbin housing between the path of movement of the needle and of the retaining finger of the bobbin housing.

2. Thread cutting device in accordance with claim l, where said thread catcher has a groove on its upper surface extending in the direction of said point, said groove terminating in an edge defining acounter cutter for said cutter, a'thread guide having a thread guiding surface disposed above said thread catcher movable above said groovealong a path of movement parallel to the path of movement thereof opposite to the path of movement of said thread catcher.

3. Thread cutting device in accordance with claim 2 where said cutter is disposed between said thread guide and said thread catcher and movable in opposite direction during the pull-out movement of said thread catcher along a path of movement extending parallel to the path of movement of said thread catcher.

4. Thread cutting device in accordance with claim 3, where said thread catcher, said thread guide and said cutter are arranged coaxially relative to one another and along paths of movement extending eccentrically to said looper.

5. Thread cutting device in accordance with claim l, where' I UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 5,658,021 Dated Alm 25,1972

Inventods) Kristen Hedegaard, Anton Leesmeieter` It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: `Amend tne title of the a plceton es follows: lllllllGEnEl=ifl` EUR CUTTINE ebeteet, line l: page 2, line 45| pee lines and 27; and Page 9, lines 14 and l5 Change dou le' to --leek;

Page 2, line 5 delete "OT eeteher"';

Page 5, line l5 Chengje *"etovp" to retaining-q Page 5 line j da.,lete"neusing'Ventend insert instead "member finger-e;-

llagge 9, line 2e, and Page lO, line Zend lines O/l, Change "nousinte` member" to boletin membefflnger;

l) e l5, line l9 delete "tneed vfeede" and nert instead y talee-up lever-- t Signed and sealed thisv 15th day of August 1972.

THREADS ON LOCK Sl TCH SEWING MEMBRES-- (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestng Officer CommissionerI of Patents USCOMM'DC 50376-P69 U.S. GOVERNMENT PRINTING OFFICE |959 0 365-334

Claims

1. Thread cutting arrangement for double stitch sewing machines having a looper turning in a horizontal plane, a needle movable relative to said looper, a bobbin housing journalled in the looper, a stitch plate disposed above said looper having an abutment, said housing having a retaining finger for engaging said abutment to secure the same against rotary movements and having an outlet opening for the looper thread determining the course of the looper thread between said stitch plate and said bobbin housing, a cutter below said stitch plate, a thread catcher having a catcher point movable in a horizontal plane and cooperating with said cutter and having a recess for accommodating the needle and looper threads adjacent said point, where the opening for the looper thread is disposed below the plane of the surface of the bobbin housing on the housing surface facing said needle, and adjacent the retaining finger, said point of said thread catcher being movable below the plane of the surface of the bobbin housing between the path of movement of the needle and of the retaining finger of the bobbin housing.

2. Thread cutting device in accordance with claim 1, where said thread catcher has a groove on its upper surface extending in the direction of said point, said groove terminating in an edge defining acounter cutter for said cutter, a thread guide having a thread guiding surface disposed above said thread catcher movable above said groove along a path of movement parallel to the path of movement thereof opposite to the path of movement of said thread catcher.

5. Thread cutting device in accordance with claim 1, where the lower part of said bobbin housing is provided with a bearing rib laterally of said retaining finger, a recess to which said finger extends, and the upper part of said bobbin housing has a bridge extending into said recess at the lower end of which said opening for the looper thread is provided.