US3476067A

US3476067A - Sewing machines with needle and loop taker operable not in predictably timed relationship

Info

Publication number: US3476067A
Application number: US690868A
Authority: US
Inventors: Ralph E Johnson
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1966-02-03
Filing date: 1967-12-15
Publication date: 1969-11-04
Anticipated expiration: 1986-11-04

Description

NOV. 4, 1969 JOHNSON 3,476,067

. SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLY TIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet 1 INVENTOR.

Ralph E. Johnson BY wylrronwr NOV- 4. 1969 R. E. JOHNSON SEWING MACHINES WITH NEEDLE AND LOOP TAKER QPERABLE NOT IN PBEDICTABLY TIMED RELATIONSHIP riginal Filed Feb. :3, 1966 5 Sheets-Sheet 2 INVENTOR. Ralph E. Jalmsan I BY W 2;T0AWY 3,476,067 ITH NEEDLE AND LOOP TAKER OPERA BLE Nov. 4, 1969 R. E. JOHNSON SEWING MACHINES W NOT IN PREDICTABLY TIMED RELATIONSHIP inal Filed Feb. 5. 1966 Orig 5 Sheets-Sheet Fig. 5.

mvsmox. Ralph E. Johnson Nov. 4, 1969 R. E. JOHNSON 3,475,067

SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLY TIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet;

Ralph E. Johnson BY W gamma-r I34 37 I52 '55 I I50 I36 E 4k I04 B2133 5 I20 I21 I22 Fig 7 INVENTOR. I

Nov. 4. 1969 R. E. JOHNSON 3,476,067

SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLY TIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet Fig.ll.

BAR CRANK ANGLE 6 80" DEAD l N VENTOR. Ralph E. Johnson BY anna/Mr United States Patent SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLY TIMED RELATIONSHIP Ralph E. Johnson, Boonton, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Original application Feb. 3, 1966, Ser. No. 524,949, now Patent No. 3,420,200, dated Jan. 7, 1969. Divided and this application Dec. 15, 1967, Ser. No. 690,868

Int. Cl. Db 57/14, 69/02, 49/00 US. Cl. 112-182 4 Claims ABSTRACT OF THE DISCLOSURE A lockstitch sewing machine is disclosed having a reciprocating needle and a rotating loop taker with a drive providing for a nominal speed ratio of three revolutions of the loop taker during each needle reciprocation. The drive for the loop taker is, however, a smooth belt incapable of maintaining a precise timed relationship between the needle and loop taker. A needle thread take up mechanism is disclosed which provides in a novel and advantageous manner for the wide variations in thread demand which are occasioned by the untimed operation of the loop taker and needle of this sewing machine.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a division of my co-pending U.S. patent application Ser. No. 524,949, filed Feb. 3, 1966 and now U.S. Patent No. 3,420,200, dated Jan. 7, 1969.

FIELD OF THE INVENTION This invention relates to lockstitch sewing machines and particularly sewing machines in which the loop taker and the needle are operable in untimed relationship.

It is an object of this invention to provide a sewing machine construction in which a drive for the needle and loop taker provides for a nominal speed ratio therebetween but without provision for maintenance of a predicatable relationship in time as between the motion of the needle and loop taker and to provide an organization of sewing machine parts and devices ancillary to the needle and loop taker which can advantageously accommodate the variations in sewing conditions occurring because of the absence of predictable timed relation be- 1 tween the needle and loop taker.

DESCRIPTION OF THE PRIOR ART Without exception, conventional sewing machines have heretofore provided actuating mechanism for operating the needle and the loop taker in precisely timed relationship. Although a wide variety of inventions have heretofore been used for needle and loop taker actuation including non-uniform velocities, dwells etc., the motions of needle and loop taker have always been precisely interrelated. In my prior US patent application Ser. No. 439,420, filed Mar. 12, 1965 and now U.S. Patent No. 3,386,401 dated June 4, 1968 is disclosed a sewing machine in which a needle and loop taker are capable of sewing lockstitches while being actuated by completely separate and unrelated sources of motive power, i.e., with complete absence of any timed relation therebetween.

3,476,067 Patented Nov. 4, 1969 "ice SUMMARY OF THE INVENTION DESCRIPTION OF THE DRAWINGS With the above and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combination and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 represents a perspective view of the sewing machine frame together with the stitch forming instrumentalities, actuating mechanism, and control means therefor in modular form in accordance with this invention with each module shown detached from the sewing machine frame,

FIG. 2 represents a head end elevational view of an assembled sewing machine of the type illustrated in FIG. 1 and including a supporting base and an electric drive motor,

FIG. 3 represents a handwheel end elevational view of the assembled sewing machine of FIG. 2, with a portion of the handwheel broken away exposing the stitch length adjusting means,

FIG. 4 represents a front elevational view of the assembled sewing machine of FIG. 2 with portions of the actuating mechanism illustrated in vertical cross section,

FIG. 5 is an enlarged cross sectional view taken substantially along line 5-5 of FIG. 2 illustrating the work feeding mechanism,

FIG. 6 represents a top plan view of the loop taker module of this invention as secured in place on the sewing machine frame,

FIG. 7 is a cross sectional view taken substantially along line 7-7 of FIG. 6 illustrating the loop taker,

FIG. 8 is a top plan view of the loop taker of this invention,

FIG. 9 is a top plan view of the bobbin case,

FIG. 10 represents a head end elevational view of an assembled sewing machine of the type illustrated in FIG. 1 and including a portion of an end cover plate applied thereto together with a representation of the path of motion of the needle thread take up eyelet, and

FIG. 11 is a graph indicating the thread demand of the stitch forming instrumentalities as compared with the thread control attained by the take up.

Referring particularly to FIG. 1, the machine frame is indicated generally at 11; the sewing needle module at 12; the loop taker module at 13; and the actuating and control module at 14.

The frame 11 comprises a C shaped member which may be of uniform cross section and includes a pair of sub: tantially parallel

free extremities

15 and 16 joined by a Cl nnecting portion 17. The frame may be fabricated in tl is shape by a bending or forging operation or it may be cast in this shape. Only two accurately machined surfaces are required on the frame 11 and in the preferred embodiment illustrated in the drawings these surfaces are a cylindrical portion 18 turned on the free extremity of the arm 15 to accept the sewing needle module 12, and a slabbed portion 19 milled on the free extremity of the arm 16 upon which the loop taker module 13 is located. The axis of the cylindrical portion 18 is preferably parallel to the plane defined by the slabbed portion 19 and the distance therebetween is preferably formed to an accurate predetermined dimension. The frame 11 may also be formed with provision for fastenings, such as tapped

holes

20 and 21 illustrated in FIG. 1, to accommodate

fastening screws

22 and 23 for the actuating and control module 14, the tapped holes 24 and 25 to accommodate fastening screws 26 and 27 for the loop taker module 13, and the tapped hole 28 to accommodate the fastening screw 29 for a supporting block 30 illustrated in FIG. 4. It will be appreciated, however, that other known types of fasteners such as clamps might be used in place of these threaded fasteners which would not require any machining of the frame 11 for the fasteners and the tapped

holes

20, 21, 24, 25 and 28 need not be located with a high degree of accuracy.

The needle module 12 comprises a support plate 40 to the inside surface of which is secured a block 41 formed with a bore 42 which may be accommodated on the cylindrical machined surface 18 of the frame arm 15. The block 41 is drilled and tapped, as at 43, for a set screw 44 by which the needle module 12 may be secured relatively to cylindrical machined surface 18 is selected axial and angular positions thereon.

To the outside surface of the support plate 40 is secured a bracket 45 between the outturned arms 46 and 47 for endwise reciprocatory motion is a needle bar 49 carrying at its lower extremity a needle clamp 50 in which an eye pointed thread carrying sewing machine needle 51 is secured. The upper extremity of the needle bar is transversely apertured to accommodate a pivot screw 52 which carries a roller 53 which rides in a guide slot 54 in the support plate to prevent turning of the needle bar.

The support plate 40 above the guide slot 54 is formed with concave bearing seat 55 having the shape of a spherical section. Accommodated in the bearing seat 55 is the spherically shaped collar portion 56 of a stud shaft 57 formed with an axial bore 58. The stud shaft 15 formed integrally with a crank arm 59 at one side of the collar portion 56 and adjacent to the other side of the collar portion, the stud shaft is externally shouldered and accommodates a bifurcated leaf spring 60 secured by a fastening screw 61 to the support plate 40, yieldingly constraining the collar portion against the bearing seat.

Pivotally connected to the crank arm 59 by a pivot pin 62 is the upper extremity of a needle bar drive link 63 which is formed at the lower extremity with an inturned clevis 64 straddling the upper extremity of the needle bar 49 and pivotally connected thereto by the pivot screw 52. The needle bar drive link 63 is formed opposite the clevis 64 with a rearwardly extending take up arm 65 terminating in a thread accommodating eyelet 66 which, as will be described hereinbelow, controls and meters the thread which is directed to the eye of the needle.

Also endwise slidable in the outturned arms 46 and 47 is a presser bar 70 having a conventional presser foot 71 secured to its lower extremity. A lateral stud 72 secured to the presser bar extends through a guide slot 73 in the support plate 40 to prevent the presser bar from turning. The lateral stud 72 is engaged by one arm of a coil spring 74 of which the other arm abuts beneath the block 41 so as to bias the presser foot downwardly. A presser lifting cam member 75 pivoted on the support plate 40 may also be disposed beneath the lateral stud 72 by which the presser foot may be elevated.

The outturned arms 46 and 47 of the bracket 45 may support a sheet metal guard plate 80 to which is secured a conventional thread tensioning device 81 which includes thread tensioning friction disks 82, a conventional check spring 83 and a thread guiding post 84. Thread from a source of supply (not shown) is directed to the friction disks 82 of the thread tension device 81 looped about the check spring 83 and thence to the take up eyelet 66. From the take up eyelet the thread is directed through a thread guiding eyelet 85 formed in a pin 86 adjacent to the thread tensioning device 81, next to a thread guide 87 secured to the guard plate 80, and then to the needle eye.

The loop taker module 13 is assembled on a plate 100, which is drilled to accommodate

fastening screws

101 and 102 threaded into tapped holes 24 and 25, respectively, in the frame 11 by which the plate is secured on the surface 19. Preferably, the screw 101 is formed with a shouldered head 103 serving to locate the loop taker in sewing position as will be described hereinbelow. Assembled-on the plate 100 and sustained in cooperating relation as a unitary module therewith are the loop taker, indicated generally as 104, the work feeding instrumentalities, indicated generally as 105.

The loop takes is carried by a swinging frame hinged to the plate 100. The swinging frame comprises an upper arm 106 which extends above the plate 100, and a lower arm 107 rigidly secured to the upper arm by a spacer 108. A second spacer 109 secured to the lower arm 107 is drilled and tapped for a headed hinge screw 110 which is extended through both the plate 100 and the upper arm 106 and bears against the upper arm by way of a spring washer 111. Encircling the second spacer 109 is a two armed Wire spring 112 of which one arm bears against the frame arm 16 and the other bears against the spacer 108 to bias the swinging frame toward the plate 100. An abutment 113 formed on the upper arm 106 of the swinging frame engages the shouldered head 103 of the fastening screw 101 to locate the swinging frame in a predetermined operative position relatively to the path of reciprocation of the needle 51.

The loop taker 104 as illustrated in the drawings, is carried by the swinging frame and is so disposed thereon as to occupy a position cooperative with the needle 51 in the formation of stitches when the swinging frame abutment 113 is seated against the shouldered head 103 of the factening screw 101. The loop taker may be of any known or conventional type suitable for the formation of either chain or lockstitches as may be desired. Indeed, the novel organization of the sewing machine of this invention provides for the ready exchange of loop taker modules 13 to substitute one type of loop taker for another. The loop taker illustrated on the accompanying drawings is a lockstitch forming loop taker which operates in accordance with the principles set forth in my above mentioned copending US. Patent No. 3,386,401, to which reference may be had, which does not require that the loop taker be driven in any predetermined timed relationship with the needle reciprocation. Moreover, the specific features of construction of the loop taker illustrated in the accompanying drawings also forms the subject of my co-pending US. patent application Ser. No. 537,065, filed Mar. 24, 1966 and now U.S. Patent No. 3,382,826, dated May 14, 1968, to which reference may be had, only that brief description of the loop taker will be set forth hereinbelow as will provide an understanding of the operation of the sewing machine of this invention.

Referring particularly to FIGS. 7 and 8, the loop taker 104 takes the form of a rotary hook and includes an inverted conical basket secured by pins 121 to the upstanding collar portion 122 of a belt pulley 123. The pulley 123 is freely journaled on a bushing 124 surrounding a stationary cylindrical post 125 which is secured, as by a screw 126, to the lower arm 107 of the swinging frame. Secured, as by a force fit into a shallow counterbore 127 in the rim of the basket 120, is a flat annular ring 128 formed with a plurality of internally extending thread seizing beaks 129. A pin 130 set into the basket in a notch 131 in the ring 128 serves to lock the ring for rotation with the basket.

A bobbin case supporting tray 132 is fixed to the top of the stationary post 125 within the rotary hook basket 120. The stationary tray is formed with a flat bottom 133 and with two angularly arranged

upstanding sidewalls

134 and 135 which support and locate a bobbin case, indicated generally at 136. The bobbin case 136 is formed with angularly arranged

side surfaces

137 and 138 which abut the tray sidewalls and with a flange 139 which overlies the flat angular ring 128 of the rotary hook. The underside of the bobbin case rests upon the fiat bottom 133 of the tray except where the bobbin case is formed with a shallow recess 140 shaped generally circular but with a chord 141 extending across the one side.

The upper arm 106 of the swinging frame is formed with an opening 150 above the rotary hook which exposes a cavity 151 in the bobbin case adapted rotatably to accommodate a thread carrying bobbin 152. A spring finger 153 secured by a pivot screw 154 to the upper arm 106 of the swinging frame overlies and bears downwardly against the bobbin 152 and thus also biases the bobbin thread case upon the stationary tray 132. A leaf spring 155 carried on the upper arm 106 also engages the bobbin case side surface 138 serving to constrain the bobbin case yieldingly in position within the rotary hook.

The loop taker module may also carry the work feedfeeding instrumentalities of the sewing machine particularly wherein a drop feed is desired such as that illustrated particularly in FIGS. 5, 6 and 7. It is pointed out, however, that using the module concept of construction as taught by this invention, other forms of work feed mechanism might be used, as for instance, a top feed mechanism carried by the needle module 12 might be employed.

Referring to FIGS. 5, 6 and 7, the drop feed mechanism 105 includes a feed dog 160 arranged beneath the presser foot 71. The forward extremity of the feed dog rests upon the plate 100 and in the rearward extremity is formed with a notch 161 embracing the upper portion of a rock arm 162 which is fast on a rock shaft 163. The rock shaft 163 is journaled in spaced bearing lugs 164 downturned from a bar 165 which is supported beneath the plate 100 by two spacers 166. A throat plate 167 formed with slots 168 accommodating the feed dog and with a needle aperture 168' is secured to a vertical stud 169- which is slidable vertically in a hole 170 in the plate 100 and a hole 171 in the bar 165. Pivoted to the stud 169 on a pin 172 is a lever 173 to which is pivoted, as at 174 a fulcrum roller 175 which snugly fits between the underside of the plate 100 and the bar 165. Movement of the lever 173 causes the throat plate to rise and fall alternately to cover and to expose the feed dog through the throat plate slots. Oscillation of the rock shafts 163 serves to reciprocate the feed dog along the throat plate slots. Operation of the feed mechanism, therefore, requires simply that rocking movement be imparted to the lever 173 and that related oscillatory movement be imparted to the rock shaft 163.

The means for importting such related operative movement to the feed mechanism as well as for imparting turning movement to the loop taker and to the needle bar driving crank are provided in the actuating module 14 which will now be described.

The actuating module 14 is assembled on a supporting plate 180 which is affixed to the connecting limb 17 of the frame 11 by the aforementioned fastening screws 22 and 23. As illustrated in FIG. 4, the supporting plate 180 is formed near the top with a concave bearing seat 181 having the shape of a spherical section.

A bushing 182 having a spherically shaped peripheral portion 183 accommodated in the bearing seat 181 is formed with an external shoulder 184 upon which a bifurcated spring 185 engages to hold the bushing resiliently in the bearing seat 181. The spring 185 is secured to the plate 180 by a headed adjusting pin 186 which passes through the plate 180. A finger grip 187 projects from the headed pin 186 so that the machine operator may at will change the angular position of the pin 186, and at the opposite side of the plate the pin 186 has secured to it a collar 188 formed with a diametrical slot 189 for regulating the feed stroke of the work feeding mechanism.

Journaled in the bushing 182 is a shaft 200 adapted at the free extremity to be accommodated in the axial bore 58 of the stud shaft 57 on the needle module 12. A flat 201 formed on the shaft 200 may be used in cooperation with a set screw 212 threaded into the stud shaft 57 to secure the stud shaft onto the shaft 200. A counterweight 203 may also be provided fast on the shaft 200 to minimize vibration of the sewing machine.

Secured to the shaft 200 by a set screw 204 is a feed driving eccentric 205 which in the assembled relation of parts is spaced from the bushing 182 by a collar 206. Secured to the eccentric 205 by screws 207 is a handwheel 208 formed with two annular

belt pulley grooves

209 and 210. The belt pulley groove 209 accommodates a drive belt 211 from any suitable source of power, such as for instance, as a drive pulley 212 on the electric motor 213 supported on a bracket 214 secured by screws 215 to the plate 180. The belt pulley groove 210 accommodates a drive belt 216 which runs over a pair of

idler pulleys

217 and 218 carried on the plate 180 and is directed about the pulley 123 on the loop taker 104. Preferably using the thread manipulating and stitching instrumentalities illustrated in the drawings, the handwheel pulley 210 is three times the diameter of the pulley 123 on the loop taker so that a speed ratio of approximately three revolutions of the loop taker will be maintained for each reciprcation of the needle.

For driving the work feeding mechanism, the feed driving eccentric 205 is embraced by two

pitman straps

220 and 221 which, as illustrated in FIG. 3, extend substantially at right angles to each other. The pitman strap 220 extends substantially vertically downward and is pivoted to a cylindrical boss 222 formed on a vertical link 223 which is constrained to move in a slot 224 in the supporting plate 180. At the lower extremity the link 223 is formed with a lengthwise slot 225 along which an extension abutment 226 may be selectively clamped between nuts 227 and 228 on a headed fastening screw 229. The extension abutment 226 may be formed with an inturned tang 30 extending into the slot 225 to prevent the abutment from turning. The fastening screw 229 extends through a vertical guide slot 231 formed in the plate 180.

FIG. 5 illustrates the position of parts when both the actuating module 14 and the loop taker module are assembled on the frame 11. The feed lift lever 173 will pass through the guide slot 231 beneath the abutment extension 226. A tension spring 232 arranged to act between the lever 173 and an anchor pin 233 fixed in the plate 182 biases the lever 173 into engagement with the. abutment extension 226.

Referring to FIGS. 3 and 5, the feed advance rock shaft 163 extends through an aperture 239 in the plate 180 when the parts are assembled on the frame. A rock arm 240 is secured to the rock shaft 163 by a set screw 241. A link 242 pivoted to the rock arm 240 by a pivot pin 243 is also connected by a pivot pin 244 to the pitman strap 221 which extends generally horizontally from the feed eccentric 205. Journaled on the pivot pin 244 is a slide block 245 which is constrained to move along the diametrical slot 189 in the collar 188. Adjustment of the angular position of the slot 189 by means of the finger grip 187 will determine the direction in which the work will be fed and the length of the feed step at each stitch.

In assembling the sewing machine of this invention, the support block 30 of the frame 11 may be secured to a base 250 or to a table, carrying case, or the like as is desired. The actuating module 14 is then secured in place by the

screws

22 and 23. The loop taker module 13 is then secured in place using the

screws

101 and 102 taking care that the feed lift lever 173 is inserted through the slot 231 and the feed lift rock shaft is inserted into the bore in the rock arm 240 in the actuating module support plate 189 when the spring 232 is attached to the feed lift lever 173. The set screw 241 is tightened to complete the feed advance connection, and when the belt 216 is entrained on the

pulleys

123, 210, 217 and 218, and the loop taker and work feed mechanism will be operatively installed on the frame.

The needle module 12 is then installed simply by placing the bore 42 of the block 41 on the cylindrical portion 18 of the frame arm 15 and simultaneously inserting the shaft 200 in the axial bore 58 of the stud shaft 54. The support plate 40 of the needle module 12 may then be turned and slid axially upon the cylindrical portion 18 of the frame until the needle 51 is accurately aligned with the needle aperture 168' of the throat plate on the loop taker module in place. The set screw 202 is then tightened to connect the needle bar drive and the sewing machine will be completely assembled.

Since the stud shaft 57 is accommodated in a spherical bearing seat 55 in the support plate 40 of the needle bar module, and the bearing seat 181 for the shaft 200 in the supporting plate 180 of the actuating module is similarly spherical, considerable variation in the relative positions of the

support plates

40 and 180 on the frame 11 may be accommodated without binding of the shaft 200. The construction of the needle thread take up arm 65 as an integral part of the needle bar drive link 63 makes possible this advantageous utilization of the

self aligning bearings

55, 181 because this take up construction obviates the need for any anchor links between the take up arm 65 and the supporting frame as exist in conventional link type take ups. A shaft which drives a conventional link take up having a pivot pin or anchor link connection with the machine frame must be manufactured in predetermined spacing and alignment with the pivot pin or anchor link connection, which requirement in the present invention would obviate the advantages of the

self aligning bearings

55, 181.

Referring to FIGS. 2 and 10, it will be noted that the take. up arm 65 projects toward the rear of the sewing machine substantially perpendicularly from the needle bar drive link 63 at a point opposite the pivotal connection provided by the pin 52 with the needle bar. Moreover, the distance of the take up eyelet 66 from the pivot pin 52 is approximately twice the distance between the pivot pins 52 and 62. With this construction, as illustrated in FIG. 10, the path of the eyelet 66 on the take up arm is a flattened figure eight oriented substantially parallel to the axis of the needle bar 49. Optimum efficiency of thread metering will thus be obtained relatively to the check spring 83 about which the thread approaches the eyelet 66 and the thread guide eyelet 85 to which the thread extends from the eyelet 66, since both the check spring 83 and the eyelet 85 may be arranged at substantially the same distance from the axis of the needle bar reciprocation as is the path of rotation of the take up eyelet 66.

As illustrated in FIG. 10, the path of motion of the take up eyelet 66 substantially parallel to the axis of the needle bar makes possible effective and convenient shrouding of the operating mechanism on the needle bar module 12 by a cover plate 250 which may follow the functional substantially rectangular outline of the support plate 40, without the requirement for flanges, lips, or extensions, in order to shroud the movement of the take up arm 65.

The graph illustrated in FIG. 11 indicates the cooperative relationship between the manner in which the needle thread is metered by the take up eyelet 66 and the demands of the stitch forming instrumentalities upon the needle thread during stitch formation. This graph plots as abscissa the needle bar crank angle, and as ordinate the total lengths of thread on the one hand as made available by the take up, and on the other hand as demanded by the stitch forming instrumentalities including the rotary hook 104 which is driven at approximately three revolutions for each needle reciprocation. The curve illustrated in dashed lines and labeled TAKE UP indicates the thread made available at each crank angle by the take up while the curve illustrated in solid lines indicates the corresponding thread demanded by the stitch forming instrumentalities.

As described hereinabove, the loop taker 104 is preferably of the type in which the motion imparted to the needle loop seizing beaks 129 need not be timed precisely relatively to the needle reciprocation, it being immaterial to stitch formation which of the beaks 129 seized the needle thread. The thread demand curve in FIG. 11, therefore, from the points A and B to the points C and D widens into an area or family of parallel curves depending at each stitch upon the actual time at which loop seizure occurs. Similarly from the points C and D to the point E the demand must be represented by a family of curves since the cast off of the thread from a stored position on the bobbin case may be influenced by the actual time at which loop seizure occurs.

Whereas in conventional lockstitch sewing machines in which the loop taker is driven in precise timed relation with the needle reciprocation, the take up need satisfy only one predetermined thread demand, in the machine of the preferred form of this invention, the take up must satisfy whichever one of the family of different thread demands may occur. As illustrated in FIG. 11 the thread supplied by the take up of this invention adequately incompasses the entire range of thread demands which are imposed by these stitch forming instrumentalities.

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

1. A sewing machine for forming lockstitches comprising in combination an endwise reciprocatory needle bar, a thread carrying needle secured to said needle bar, drive means for said needle bar including a rotary crank means and a drive link pivotally connected to said crank means and to said needle bar, a rotary loop taker having a plurality of needle loop seizing beaks disposed to move in a path complemental to said thread carrying needle, drive means for imparting rotation to said loop taker not in predictably timed relation with said needle reciprocation and at a nominal rate of substantially three revolutions during each reciprocation of said needle bar, said rotary loop taker forming stitches with a needle thread seized from said needle when said needle is operated not in predictably timed relation with said rotary loop taker, and a needle thread take up arm extending laterally from said needle bar drive link and formed with a thread guiding eyelet providing a take up for thread carried by said needle.

2. A sewing machine as set forth in claim 1 characterized in that said drive means for said needle bar connected to said needle bar crank, and in which said drive means for said loop taker comprises a belt having a uniform cross sectional configuration operatively connecting said shaft with said loop taker.

3. A sewing machine as set forth in claim 1 in which an imaginary line passing through said thread engaging eyelet and the pivoted connection between said needle bar with said needle bar drive link extends substantially perpendicular to an imaginary line joining the axes of the pivoted connections of said needle bar drive link with said crank means and with said needle bar, and in which said take up arm is substantially twice the length of said needle bar drive link.

4. A sewing machine as set forth in claim 3 in which a pair of thread guides are carried by said sewing machine, one for each limb of a loop of thread directed to said take up thread engaging eyelet, said thread guides being disposed in close proximity one to the other both at 9 10 the same side of the path of motion of said take up thread FOREIGN PATENTS engaging eyelet and both substantially at the same dis- 722,668 7/1942 Germany tance from the axis of needle bar reciprocation as is the path of motion of said take up thread engaging eyelet. HAMPTON HUNTER, Primary Examiner References Cited 5 C1. UNITED STATES PATENTS 112--184, 220, 241

1,062,696 5/1913 COX 112-181 1,129,588 2/1915 Onderdonk 112241 2,633,092 3/1953 Robert et a1. 112220 10