US2712805A

US2712805A - Feed-off-the-arm sewing machine

Info

Publication number: US2712805A
Application number: US300216A
Authority: US
Inventors: Albert C Peterson; Albert M Schweda
Original assignee: Union Special Machine Co
Current assignee: Union Special Machine Co
Priority date: 1952-07-22
Filing date: 1952-07-22
Publication date: 1955-07-12
Anticipated expiration: 1972-07-12

Description

y 1955 A. c. PETERSON ETAL 2,712,805

FEED-OFF-THE-ARM SEWING MACHINE 5 Sheets-Sheet 1 Filed July 22, 1952 MA V Y 0 D E R N N E W R ET H O E T N P S I m C M mm M; LL AA Y B @NN Q.

s I v.

July 12, 1955 A. c. PETERSON ET AL 2,712,805

FEED-OF'F-THE-ARM SEWING MACHINE Filed July 22, 1952 5 Sheets-Sheet 2 FIG.2

ATTORNEY.

y 1955 A. c. PETERSON ET AL 2,712,805

FEED-OFF-THE-ARM SEWING MACHINE Filed July 22, 1952 5 Sheets-Sheet 3 INVENTORS. ALBERT C. PETERSON ALBERT M. SCHWEDA ATTORNEY.

July 12, 1955 A. c. PETERSON ET AL 2,712,805

FEED-OFF-THE-ARM SEWING MACHINE 5 Sheets-Sheet 4 Filed July 22, 1952 INVENTORS. C. PETERSON ALBERT BY ALBERT M. SCHWEDA ATTORNEY.

July 12, 1955 A. c. PETERSON ET AL 2,712,805

FEED-OFF-THE-ARM SEWING MACHINE.

5 Sheets-Sheet 5 Filed July 22, 1952 FIG. 2!

INVENTORS. ALBERT C. PETERSON ALBERT M. SCHWEDA BY ATTORNEY.

United States Patent 0 pal 2,712,805 FEED-OFF-THE-ARM SEWING MACHINE Albert C. Peterson, Park Ridge, and Albert M. Schweda,

Chicago, 11L, assignors to Union Special Machine Company, Chicago, 11L, a corporation of Illinois Application July 22, 1952, Serial No. 300,216 13 Claims. (Cl. 112-252) This invention relates to an improved feed-off-the-arm sewing machine having a free ended work supporting arm and stitch-forming and work-feeding devices arranged to form a thread chain and to feed ofi the free end of the arm.

it is an important object of the present invention to provide a thread chain cutter which is particularly adapted for use with a machine of the general type described for automatically severing the thread chain formed at the trailing edge of each Work piece as it is fed from the machine.

A further object thread cutting device which can be maintained continuously in operation and which automatically severs the thread chain formed between the successive work pieces without adversely affecting the work pieces or the stitching thereof.

It has been a purpose of the invention to cause the completed work to be guided away from and clear of the cutting edge, whereas any unsupported portion of the thread chain connected with either the trailing or leading edge of the work piece is automatically brought into engagement with the cutter edge and trimmed away.

Other objects of the invention are to improve the construction and arrangement of the operating mechanism supported in the work arm, including certain connections therein provided from the looper rock shaft for continuously actuating the thread cutter, and a novel and more compact arrangement of the looper rock shaft in relation to a feed dog lift lever which makes possible a reduction in size and a further streamlining of the work arm.

in accordance with the invention vice is provided at the free end of the work arm and is maintained in continuous operation while the machine is running and serves automatically to engage and sever from the work any unattached portion of the thread chain passing over the thread cutting device. The cutting der vice provided in accordance with the invention consists specifically of a transversely movable cutter bar having a serraEd or toothed cutting edge, and a cooperating relatively stationary cloth guard which is similarly formed with a serrated or toothed edge, tend substantially above the cutting edge of the cutter bar. The thread cutting device referred to is mounted on the free end of the sewing machine work arm, so that the toothed edges of the cutter bar and the cloth guard are located in an upright position across the work arm beyond the end thereof. The cutter bar is continuously driven during the operation of the machine through connections which receive motion from the rocking movements of the looper rock shaft in the work arm. In one embodiment of the invention the operating connections referred to are constructed and arranged for manual adjustment to permit the thread cutting device to be simply and readily thrown out of action.

In order that any freely extending, unattached portion of the thread chain may be immediately and continuously brought into engagement with the moving cutting edge of the thread cutting device, means are provided for diis to provide a simple and efiicient cleanly and efiiciently a thread cutting dethe teeth of Which eX- recting a stream of air against and along the work arm, downwardly and in the direction of feed, adjacent the free end of the arm in the region of the cutting device. The force of the airstream is not sufiicient to interfere with the feed of the work along the work arm but is effective to position any unsupported or unattached portion of the thread chain in the path of the moving cutter bar of the cutting device. The direction of the airstream is such as to direct the loose end of the chain extending from the leading edge of a Work piece into the cutting zone of the cutting device so that the chain will be cut into small sections and will be trimmed closely at the leading edge as well as the trailing edge of the Work.

With the objects above noted in View, the invention comprises also certain novel features of the construction and arrangement of the several parts hereinafter described and claimed, which together with the advantages to be obtained thereby will be readily understood by one skilled in the art from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation of the illustrative machine, a portion of the frame or housing being broken away to disclose some of the interior mechanism;

Fig. 2 is a vertical central section through the work supporting arm and connected portion of the frame of the machine;

Fig. 3 is a fragmentary view in vertical section, showing a portion of the mechanism illustrated in Fig. 2 but with some of the superposed parts removed;

Fig. 4 is a fragmentary plan view of the outer end of the work arm;

Fig. 5 is a vertical section through a portion of the frame of the machine, taken along line 55 of Fig. 1, showing the connection between the main drive shaft and the looper shaft in normal operative position;

Fig. 6 is a fragmentary view in elevation, of a portion of the work arm showing the manner in which the thread chain is cut upon the removal of a work piece from the machine;

Fig. 7 is a fragmentary view on the blower mounted on the head of from the left in Fig. l and with the cover removed;

Fig. 8 is an end view of the work supporting arm showing the thread cutting device mounted thereon;

Fig. 9 is a view similar to Fig. 8 but with the underlying an enlarged scale of the machine looking movable thread cutter blade embodied in Fig. 9;

Fig. 11 is an end view of the cutter blade shown in Fig. 10.

Fig. 12 is a view of the end of the work arm with the cover plate, thread cutter bar and actuating lever removed to show the stationary but vertically adjustable cloth guard;

Fig. 13 is a view similar to Fig. 9 but with a portion of the cover plate removed and the remainder thereof shown in section to show more clearly the underlying parts;

Fig. 14 is a detail shaft;

Fig. 15 is a' detail sectional View taken along the line E1515 of Fig. 2 to illustrate the construction and arrangement of the looper rock shaft and portions of the feed mechanism;

Fig. 16 is a sectional view taken along view of the cutter operating drive the line 1616 the feed dog lift lever pivot; illustrate a modified form of the including means for disconnecting the thread cutting device in non-operative condition;

Fig. is a detail view of the drive shaft for the thread cutting device employed in the modified construction; and

Fig. 21 is a detail perspective view of a spring employed to hold the thread cutter drive shaft in either .&

operative or non-operative position.

The machine hereinafter disclosed as embodying, in a preferred form, the several features of theinvention is a feed-off-the-arm sewing machine in many respects similar to that disclosed in the Smith Patent No. 2,391,519, granted December 25, 1945, and in a Kucera Patent No. 2,199,666, granted May 7, 1940. Various details of the construction of the machine have been omitted from the present case and reference may be had to said Smith and Kucera patents for a full disclosure of these.

Referring now to the drawings, the machine comprises a frame which forms an enclosed housing for substantially all of the operating means. The frame includes a base member which is adapted to be supported on the top 1.;

of a table and which carries at its upper end a main frame member 32. At one end of the member 32 there is provided a laterally disposed needle head 34. At the opposite end of the member 32 is a downwardly extending member 36, forming a vertical standard, from the 1;

lower end of which projects a work supporting arm 38. The free .end of this arm extends beneath the needle head.

Within the needle head 34 there is provided a vertically reeiprocable needle bar 40 carrying one or more needles 42 at its lower end. Two needles are shown but the numberemployedmay be varied asdesired. Adjacent the needle bar there is also mounted for vertical movement within the needle head a presser bar 44 carrying at its lower 'end a presser foot 46 of any suitable construction. Within the work supporting arm 38 there is provided, for cooperation with the needle or needles, one or moreloopers 48 (Fig. 2) two being shown, one for each needle. arm a'workfeed dog 50 ofany suitable construction The feed dog has aportion adapted to pass through openings in a throat plate 52 (Fig. .4) at the top of the work supportmg arm into cooperation with thework and the presser foot. Provision is thus made for advancing the work along and off the work supporting arm and for forming desired lines of stitching as the work is advanced.

Power for operating the stitch-forming and work'feeding devices is supplied to the machine through a combined pulley and hand wheel 54 which may be connected by a belt with any suitable source of power such as a motor (not shown) appropriately mounted beneath the supporting table. Pulley 54 is secured to a horizontally disposed main drive shaft 56 of the machine which extends along the length ofthemain frame member 32. The needle bar 40 is continuously driven from the main drive shaft 56 through connections not specifically shown. The presser bar 44 is normally pressed downwardly against the work arm 38 by spring means 44:: indicated generally in Fig. 1.

The loopers 48 are secured to a holder 58 attached to the end of a looper rock shaft 60 of the machine which is suitably mounted in

bearings

62, 64 and 66 in the work supporting arm of the frame for both oscillation and lon- I gitudinal reciprocation.

To impart longitudinal, reciproca'tory movement to the looper shaft, for needle-avoid purposes, the shaft is provided with a pair of spaced collars 68 and70v which are secured thereto between

bearings

64, 66. Between these spaced collars a sleeve 72 is freely mounted on the shaft This sleeve is held against relative longitudinal move- There is also mounted within the work ment along the shaft by the fixed

collars

68, 70 but the shaft is free to rock within the sleeve. A downwardly extending fork 74, integral with the sleeve 72, straddles a flat-sided portion 76 of a pin 77 mounted in the work arm, thus preventing rotation of the sleeve while permitting bodily movement of the same with the shaft 60 relative to the frame. Astud 78 extending laterally from the sleeve 72 is connected by a screw-threaded link 80, of adjustable length, with a stud 82 carried by an arm 84 integral with a rock member 86 pivotally mounted at 85 on the machine frame. A rocking movement is imparted to the member 86 by means of a rod 90 connected at its upper end by means of a strap 92 with an eccentric on the drive shaft 56, and connected at its'lowcr end with a ball stud 94 carried by an arm of the rock member 86. Stud 82 may be adjustably secured to the arm 84 at any desired point along a slot 96 in the arm to vary the extent of the needle avoid movement imparted to the loopers. V

The loop-taking and loop-shedding movements are imparted to the loopers 48 by the oscillatory movement of the looper rock shaft 60. At its rear end the shaft '60 carries an integral crank arm 98, having a crank pin 1% connected by a pitman consisting of two pivotally connected

sections

102, 106 with a crank portion 104 at the right end (Fig. l) of the shaft 56. The sections 1 192 and 106 form a toggle connection which is normally in a straightened position as shown in Fig. 5. There is also provided, as shown in Fig. 5, a spring pressed plunger 108 which is normally maintained in a raised inactive position, but which acts when depressed to engage with a lateral extension 110 of the member 106 causing the toggle to be broken. In this manner the'loopers are unlocked and shifted outwardly beyond the normal range of oscillation and into a more accessible position for threading. 1 p

The feed dog 50 is arranged for vertical movement and for forward and return movements in a horizontal direction and to this end is secured to a bar 112 (Figs. 2 and 15)- pivotally mounted on a transverse pivot pin 114 connecting the upper ends of two vertically disposed

links

116, 118. In the illustrated construction the

links

116, 118 are carried at the ends of two parallel

forwardly extending arms

120, 122 of a lever having also a rearwardly extending arm 124 rockably mounted on two trunnions 126m fixed bearings 128 at opposite sides of the looper shaft 60 (Fig. 16). The rearwardly extending portion 124 of the feed dog lift lever'is disposed entirely at the rear side of the looper rock shaft 60 as viewed in Fig. 2. The present construction differs specifically from the prior art in that the pivot for the feed dog lift lever has been raised so that it is inthe same transverse plane with the looper rock'shaft thereby making possible a substantial economy of spaceand a consequent reduction in the cross-sectional dimension of the work arm 38. This enables use of the machine on smaller tubular Work. In order to achieve the compact arrangement shown a novel and improved construction of the feed dog lift lever is employed having a 3; wide hub through which an aperture is formed that ex- For 'moving the feed dog vertically the feed dog lift lever 124 is connected at its rear end to an upwardly extending rod 130 carrying at its upper end an eccentric .strap 132 cooperating with an eccentric on, the main I drive shaft 56. Forward and backward, or feed and return, movements. areimparted to the feed. dog 50 through connections from therocker member 86. which comprise a link 134 connected at one end with a slotted plate 136 forming a part of the rocker member and connected atfits other end by means. of a pivot pin 137 With an ann 138 rockably mounted on thefr'ame'and with the rear end of the feed dog supporting bar 112. Through the connections described four motion movements are imparted to the feed dog. The feed stroke may be varied by adjusting the position of the pivot pin at the right end of link 134 (Fig. 2) along the slot in the plate 136.

Referring specifically to Figs. 2 and 8 to 14 of the drawings, the thread cutter device comprises a cloth guard plate 150 held in a vertical position against the end face 152 of the work arm 38 with the toothed upper edge thereof extending across the end of the Work arm. The plate 150 has formed in the outer face thereof a transverse groove 154 which is engaged by a tongue 156 formed on the lower edge of a transversely movable thread cutter bar 158 which overlies the upper portion of the cloth guard plate 150 and is formed with a serrated or toothed cutting edge cooperating with the toothed edge of the cloth guard plate 150. The cloth guard plate 150 has secured in the face thereof an outwardly extending pivot pin 16?) on which is supported a cutter bar actuating lever 162. The cloth guard plate 150 is also formed with two vertical slots 164 adapted to receive locking screws 166 threaded into the end face 152 of the work supporting arm and is further provided at its lower end with a cut out section 168 K which is slidably fitted over the projecting end of a sleeve bearing 169 for a cutter bar drive shaft 179. The parts above described are held in place by means of a cover plate 172 which overlies the cutter bar drive shaft 170. The parts above described are held in place by means of a cover plate 172 which overlies the cutter bar 158, the cutter bar actuating lever 162 and the outer end of the drive shaft 170. Two inwardly extending ribs 174 formed along the side edges of the cover plate engage against portions of the cloth guard plate 150 at each side of the cutter bar actuating lever 162. Adequate clearance is provided for the free movement of these parts. The cover plate 172 is provided with two vertical slots 176 to receive the clamping screws 166 and with a circular aperture 173 to receive the pivot pin 16%) (Figs. 8 and 9). With this arrangement the several parts of the cutter device, including the cloth guard plate 150, cutter bar 153, lever 162 and cover plate 172, are keyed together by the pivot pin 160 and are vertically adjustable as a unit upon loosening the clamping screws 166 in order to accommodate various thicknesses of work in the machine, or to permit the unit to be lowered to an inoperative position as desired.

Oscillatory movements are imparted to the cutter bar 158 through connections from the looper rock shaft 6 3 which comprise the cutter bar oscillatory lever 162, the upper end of which is formed with a ball portion which fits into a centrally located slot 178 in the cutter bar. the lower end of the lever 162 is formed with a slot 189 which engages with an eccentric 182 formed on the outer end of the cutter mechanism drive shaft 179 above referred to.

The shaft 170 is supported in axial alignment with the looper rock shaft 69 in a sleeve bearing 169 and is held against axial movement by the engagement of eccentric 182 against one end of the bearing and by the engagement of a collar 185 on the shaft 170 at the other end of the bearing. Drive shaft 170 is connected to turn with the looper rock shaft 60 by the engagement of a tongue 199, formed on the drive shaft 110, with a slot 192 formed in the abutting end of the looper rock shaft. With this construction and arrangement of the cutter mechanism it will be appreciated that the cutter bar is moved first in one direction and then in the other with each rocking movement of the looper rock shaft 60 during the continued operation of the stitch forming devices. The tongue and

slot connection

198, 192 maintains a driving connection between the

shafts

60 and 170 at all times even though the shaft 60 is shifted back and forth for needle avoid purposes as described.

in amodilied form of the invention specifically illusijfi trated in Figs. 17 through 21, inclusive, means are pro vided under the control of the operator to permit the cutter mechanism to be readily thrown into and out of active operation. As shown in these figures a cloth guard plate 156, a cutter bar 158 and a cutter bar actuating lever 263. are provided which are identical with corresponding parts previously described. in the modified form of the thread cutter device however a cutter bar drive shaft 1% is provided which is particularly constructed and arranged to be moved axially between two al' "vs operative and non-operative positions in its mg 169. in the outward non-operative position of shaft 1% the tongue 1% may be fully disconnected from the slot 1=2 formed in the end of the looper rock shaft even when the latter is at the left end of its axial movement. However, the arrangement may be such, if desired, that the tongue 1% and slot 192 are never fully disengaged so that the two shafts will always be oscillated together. Disablement of the cutting device is accomplished by carrying the eccentric 2% at the end of shaft 1% out of the slot at the lower end of lever 162.

in order to permit the drive shaft 194 to be shifted to non-operative position in this manner a cover plate 13 is provided for the unit which is shortened at its lower end sufficiently to leave uncovered the end of the drive shaft 1% and its associated eccentric A spring detent 262 secured to the work arm by a set screw 204 is provided with two upwardly extending arms which engage respectively with the opposite sides of one of two detent grooves 296 and 2% in he periphery of the drive shaft 194 so that the shaft held yieldably in either of its two alternative operative and inoperative positions in which it is placed by the operator. To shift the shaft 19 into one position or the other the operator simply pushes or pulls the eccentric Further in accordance with the invention means are provided for directing a stream of air against the thread cutting device downwardly and in the direction of feed so that any unsupported and unattached portions of the thread chain formed by the stitch-formin devices in advance or" a work piece being fed along the work arm will be directeo into the cutting zone of the thread cutting device. As best shown in Figs. 1 and 7 of the drawings the air stream is generated by a sliding vane type air pump comprising a housing 211) fastened by means of a bracket 212 and a screw 214 to the machine base 39, and a rotor 216 mounted on the end of the main shaft 56. Four vanes 21% mounted in radial slots 220 in the rotor 216 are held by centrifugal force against the eccentrically formed inner face of the housing 219. Air is drawn into the pump housing through an inlet port 2.22 and is discharged through a fitting 224 and a flexible tube 225 and is delivered by the latter to a nozzle 223 having a flat wide-mouthed orifice against the cutter unit Figs. 1 and 2). Nozzle 228 is secured by a'clamp 239 to the presser bar 4 5 and partakes of slight upward and downward movement with the presser foot. Such movement is permitted by the flexible tubing 225.

Through the use of a wide orifice on the nozzle 228 it is insured that all the free thread chains formed by a plurality of needles and loopers will be brought into en gagement with the reciprocating cutter blade and severed between the teeth of ti latter and the teeth on the stationary plate 15%. T 1e air stream is directed downwardly and forwardly of the work arm in the direction of feed so that any loose ends of the thread chains which may have been formed at the leading edge a work piece being stitched on the machine will be urged directly into the cutter device. it should he noted in this connection that in the continuous use of the machine on successive work pieces, the one which has just been completed will be deflected downwardly by the operator as indicated at 235 in Fig. 6. This will carry the trailing thread chain or chains into cooperation with the cutting device. As the chain is served the free portion 2-33 extendingfor:

i frameprovided with a is present, the combination I no work is present, and means wardly from the next work piece 240 may have a tendency 24-0 advances and only the work be cut away as the work piece a small section of the chain will be left as piece passes overthe guard plate 150,

The invention having been described, what is claimed 1. In a feed-ofi-the-arm sewing 'machine, having a free ended work supporting arm, stitch-forming devices including a looper mechanism and 'a feed dog mounted'in the arm and arranged for feeding work off the free end of the arm, and a reciprocating needle cooperating with the looper mechanism to form a thread chain, and operating means within said arm for operating said looper mechanism and said feed dog,

the combination of an automatic thread chain cutter mounted beyond the free end of the arm comprising a toothed cloth guard mounted on the frame and extending across the arm beyond the end thereof, a cutter bar having a serrated cutting edge supported by the frame guard, and driving connections Within said arm from said operating means for imparting reciprocatory movements to said cutter bar. I

2. In a sewing machine having a frame with a vertical standard portion, an overhanging sewing head portion and a free-ended work supporting armtextending laterally from said standard portion with its free end beneath said sewing head, stitch-forming devices including a looper mechanism, a feed dog carried in said arm and a cooperating needle mechanism constructed and arranged to form stitching in work that is fed alongand off the free end of said arm and to form a chain when no work is present, and

operating means within said arm for operating said looper mechanism and said feed dog, the combination of an automatic thread chain cutter comprising a cutter element movably supported on the machine and continuously operating in a zone extending across the arm beyond the end thereof, and a cloth guard associated with the cutter, and connections within said arm from said operating means to said cutter element for driving the latter, said cloth guard being supported on the machine and being constructed and arranged to engage any unsupported portion of thread chain with the cutter.

3. "In a sewing machine having a frame with a vertical standard portion, an overhanging sewing head portion and a free-ended work, supporting arm extending ing head, stitch-forming devices including a looper mechanism, afeed dog carried in said arm andta cooperating needle mechanism constructed and arranged to form stitching in work surrounding said arm that is fed along and off the free end of said arm and to form a chain when no work of a thread cutter device continuously operating in a zone extending across'the arm beyond the end thereof, said thread cutter device having a continuously operated cutting element, driving connections within said arm for operating said cutting element, and means on the machine for applying a force to any for movement parallel to and in operative relation to said laterally from v said standard portion with its free end beneath said sewunsupported portion of thread chain to urge the same lengthwise of said arm and into said zone of operation 7 of said cutter device.

7 4. 'In a sewing machine having a frame with a vertical standard portion, an overhanging sewing head portion, and a free-ended work supporting arm extending laterally from said standard portion with its free end beneath said sewing head, stitch-forming and work-feeding devices including a needle supported from the, sewing head portion, a'

feed dog and a looper mechanism including a looper rock shaft extending longitudinally within said arm constructed and arranged to form stitching in work that is fed along and oif the free end of Saddam and to form a chain when for driving the stitch-form ing and work-feeding devices including means for rocking by the rocking movement of the looper rock shaft for 'moving the cutter element.

sewing machine, a machine work supporting arm, stitchforrning and work-feeding devices arranged for feeding work off the free end of the arm comprising a needle mechanism, a looper mechanism and feed dog mounted 5. In a feed-off-the-arm frame having a free-ended in the armyand an actuating mechanism including an oscillating looper rockshaft extending longitudinally within the arm, the combination of an automaticthread chain cutter comprising a toothed cloth guard mounted on the frame and extending across the arm beyond the end thereof. a cutter bar having a cutting edge extending transversely of the arm and supported for vibratory movement with relation to the cloth guard, and connections between p the loopershaft and thread cutter element rendered I tive by the oscillatory movement of the looper'rock' shaft operafor vibrating said element. 7

6. In a sewing machine having'a frame with a vertical standard portion, an overhanging sewing head portion, and a free-ended work supporting arm extending laterally from said standard portion with its free end beneath said sewing head, stitch forming and work feeding devices ineluding a needle supported from the sewing head portion, a feed dog and a looper mechanism including a looper rock shaft extending longitudinally within said arm arranged for oscillatory loop-taking and loop-shedding movements and being constructed and arranged to form stitching in work that is fed along and off the free end of said arm and to form a chain when no work is present, the combination of a thread chain cutter comprising a cutter element movably supported on the arm and having a cutting edge movable with said element in a zone extending transversely of the arm beyond the free end thereof, a cloth guard supported on the arm and positioned to guide the work away from said moving cutter edge, a cutter drive shaft arranged to'turn with the looper rock shaft, an eccentric on the'cutte r rock shaft, and a lever 7. In a sewing machine having a frame with a vertical standard portion, an overhanging sewing head and a'freeended work supporting-arm extending laterally from said standard portion with its free end beneath said sewing head, chain stitch-forming and ranged to feed off the free end of said arm including a needle supported from the sewing head portion, a feed dog and a looper mechanism including a looper supporting rock shaft extending longitudinally within said arm and being supported for axial needle-avoid and oscillatory loop-taking and loop-shedding movements, the'combination of an automatic thread cutter'unit comprising a ver tically disposed cloth guard plate carriedon the end of the arm and having across the arm,

toothed cutting edge slidably supported with relation'to' the cloth guard plate, an actuating lever pivoted on said cloth guard plate and connected with the cutter bar, a cover plate, means securing said cutter unit to the arm for vertical adjustment thereon, and a cutter'bar drive shaft arranged to'oscillate withsaid rock shaft and having an eccentric cam and follower connection with said actuate ing lever. i

8. In a sewing machine having a frame with a vertical standard portion, an overhanging sewing head portion and a free-ended work supporting arm extending laterally from said standard portion with its free end beneath said sewing head, stitch-forming-devices including a looper mechanism, a feed dog carried in'said arm and a cooperating work-feeding devices ar- 7 a toothed cloth guard surface extending a a cutter bar having a correspondingly needle mechanism constructed and arranged to form stitching in Work that is fed along and off the free end of said arm and to form a chain when no work is present, the combination of a thread cutter device continuously operating in a zone extending across the arm beyond the end thereof, and means for directing an air stream along the line of stitch formation and downwardly against the cutter for guiding and directing any unsupporte portion of thread chain into said zone.

9. In a feed-off-the-arm sewing machine, a frame having a free-ended wor' supporting arm, stitch-forming devices including a looper mechanism and a feed dog mounted in the arm and arranged for feeding work ofi the free end of the arm, and a reciprocating needle cooperating with the looper mechanism to form a thread chain, the combination of an automatic thread chain cutter mounted beyond the free end of the arm and comprising a toothed guard mounted on the frame and extending across the arm beyond the end thereof, a cutter bar having a serrated cutting edge supported by the frame a for movement parallel to and in operative relation to said guard, driving means for said stitch-forming devices connected to impart reciprocatory movement to said cutter bar, and means for directing any unsupported portion of thread chain into cooperative relation with said thread chain cutter comprising means actuated by said driving means for generating an air stream, and an air nozzle for directing said air stream against the thread cutter downwardly and in the direction of feed.

10. In a feed-off-the-arm sewing machine, a frame having a free ended work supporting arm, stitch-forming devices arranged for stitching and for sewing head, stitch-forming and work-feeding devices arranged for stitching and for feeding work off the free end of the arm comprising a needle mechanism, a looper mechanism and a feed dog mounted in the the arm and having reciprocatory needle-avoid and oscillatory loop-taking and loop-shedding movements, the combination of a thread chain cutter comprising a toothed cloth guard mounted on the frame and a movable cutter element having a toothed cutting edge cooperating therewith and extending across the arm beyond the end thereof, operating connections between the rock shaft and said movable cutter element, said operating connections being actuated by the oscillatory movement of the rock shaft for actuating said cutter element, and means for directing any unsupported portion of thread chain against the cutter comprising an air blower driven by said actuating means, and a nozzle connected thereto with the blower disposed on the frame for directing an air stream against the cutting edge downwardly and in the direction of the feed.

12. In a feed-otf-the-arm sewing machine, a frame having a free-ended work supporting arm, stitch-forming and work-feeding devices arranged for feeding Work off the free end of the arm and comprising a needle mechanism, a looper mechanism and a feed dog mounted in the arm, and an actuating mechanism including an oscillating looper rock shaft extending longitudinally within said arm, the combination of an automatic thread cutter comprising with relation to the cloth guard, and connections between the looper shaft and thread cutter element shiftable between operative and inoperative positions for transmitting said oscillatory movement to the looper rock shaft to vibrate said element.

13. In a feed-ofi-the-arm sewing machine, a frame having a free-ended work supporting arm, stitch-forming and work-feeding devices arranged for feeding work off the free end of the arm and comprising a needle a feed dog mounted in the arm and a looper mechanism including a looper rock shaft supported Within the arm for longitudinal needle-avoid movement and for oscillating loop-taking and loop-shedding movements, the combination of an automatic thread chain is shiftable axially into and out of operative position in relation to the looper rock shaft.

References Cited in the file of this patent UNITED STATES PATENTS