US1588134A - Intermittent-tension stitch-forming mechanism - Google Patents

Description

June 8 1926.

c. w. MUELLER INTERMI'ITENT TENSION STITCH FORMING MECHANISM.

Filed Feb. 14, 1924 8 Sheets-Sheet 1 anon 119$ 'llarZe-s itlfzzell r June 8 1926.

' 1,588,134 C. W. MUELLER INTERMITTENT TENSION STITCH FORMING MECHANISM Filed Feb. 14. 1924 8 s s 2 attozwuq June 8 1926.

c. w; MUELLER INTERMITTENT TENSION STITCH FORMING MECHANISM 8 Sheets-Sheet 5 Filed Feb. 14, 1924 arm m1:

June 8 1926; I

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c. w. MUELLER INTERMITTENT TENSION STITCH FORMING MECHANISM Filed Feb. 14, 1924 8 Sheets-Sheet 5 Jung s, 1926, 1,588,134

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June 8 1926. 1,588,134

C. W. MUELLER INTERMI [TTENT TENSION STITCH FORMING MECHANISM Filed Feb. 14. 1924 8 Sheets-Sheet '7 mw a 3% C. W. MUELLER INTERMITTENT TENSION STITCH FORMING MECHANISM June 8 1926.

Filed Feb. 14, 2 8 Sheets-Sheet 8 I zjwvzntoz ma W/Vueller Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

CHARLES W. MUELLER, O1 ST. LOUIS, MISSOUIEI, ASSIGNOB '10 LEWISINVISIIBLI STITCH MACHINE 00., OF ST. LOUIS, MISSOURI, A CORPORATION OF INTEBMI'ITENT-TENSION STITCH-FORMING MECHANISM.

Application filed February 14,1924. Serial No. 692,696.

' This invention relates to new and useful improvements in sewing machines enerally, although more particularly to t e stitch formin mechanism of blind stitch machines.

In bhnd stitch operations, particularly for joining a base layer and a superimposed- The principal object of my invention is to provide in a blind stitch sewing machine for joining a base. layer and a superimposed layer, an automatic intermittent tensioning mechanism for the thread or threads where-. by certain of the stitches which penetrate the superimposed layer will be set under a ti ht tension, while the remaining stitches which penetrate the superimposed layer and enterand emerge from the same face of-the base layer will be set under a loose tension, thus creating a sufficiently tight seam to meet practical requirements, and at the same time preventing the 'ap arance of dimples or uckering on the fairrside of Y the base ayer. Another object of the invention is to provide an intermittent plunger mechanism wherein the plan er at predetermined intervals elevates the base layer. into the path of reciprocation of the needle so as to insure certain of the stitches being made to penetrate the superimposed layer and enterand emergefrom the same face of the base layer, and an intermittent thread tension release mechanism, which is so timedas to permit the thread or threads ofthe stitches thus being formed to be loosely concatenated.

A furtherobjectof my invention resides in the needle thread tensioning means whereby the thread when released will still be under suflicient tension to avoid the thread being pulled from the supply when the neeture of the invention is better for general practical requirements.

With the above and Ollllel objects in view which will more readily appear as the naunderstood,

combination and arrangement of parts hereinafter more fully described, illustrated and claimed; 7

In the accompanying drawin which illustrate one embodiment of my invention, 4 I

Figure I is a perspective view of the stitching headshowing the application of my intermittent tension releasing mechanism.

Figure 2 is an end elevation of a machine embodying my invention. I

Figure 3 is a detail vertical longitudinal sectional view showing the driving mechanism of the machine.

Figure 4 is a detail vertical transverse sectional view taken on the line 44 of Fig. 3.

Figure 5 is a top plan view of the stitching head.

Figure 6 is a detail horizontal sectional view showing the intermittent tension releasin mechanism.

, igure 7 is an enlarged detail elevation of the releasing mechanism, showing the inter changeable actuating cams.

Figure 8 is a perspectlve view showing thesame consists in the novel construction,

the various (parts of the releasing mechanism in separate relation.

Figure 9 is an enlarged plan view of the seam produced by my invention.

' Figure 10 is a sectlonal view of the, seam taken on the line 1010 of Fig. 9.

Figure 1-1 is a sectional view of the seam.

taken on the line 1111 of Fi 9. Figure 12 is a detail vertical ongitudinal sectional view showing the plunger and its actuating means, the feed' dog, -and thework .clamp.

Figure 13 is'a plan view of the presser foot showing the application of the fabric.

Figure 14 is an enlarged view, more or less diagrammatic, showingthe relative positions of the plunger, the fabric, and the needle when t e superimposed layer only is being stitched.

Figure 15 is a similar view. but showing the relation of the parts when the superimosed layeris being stitched to the base ayer. v 1

ool

Figure 16 is a plan of the foot. Figure 17 is a perspective view of the cradle. 1

Figure 18 is a longitudinal sectional view of the base showing the means for supporting and depressing the work. presenting mechanism.

Figure 19 is a diagrammatic view showing the'low position of reciprocation of the plunger, and Figure is a similar view but showing the high position of reciprocation of the plun er. Li e reference numerals designate corresponding parts in all the figures of the drawlngs.

The sewing machine frame consists of a' base 5 having at one end "the work handling is a link 20. The me I mechanism, a post 6 which extends upwardly from the other end thereof and an overhanging arm 7 which is supported by the post and carries at its outer or free end a stitching head 8, said stitching head being disosed above the work handling mechanism.

e stitching head carries at its lower extremity a presser foot 9 for cooperation with the stitch forming and work handling mechanisms.

The operating parts carried b the stitching head Sand the work handing mechanism carried by the base 5 are driven from a main shaft 10 which extends longitudinally in the overhanging arm 7 and is suitably journaled therein, said shaft having a hand wheel Pulley 11 fixed to the right hand end thereo The work handling mechanism which cooperates with the presser foot 9 includes a feed dog 12 and a work clamp 13. The feed dog is of the Jr-motion t pe, that is, it has a backward and forwar movement and an' up and downmovement. vThe backward and,

forward movement of. the" feed dog is obtained through a rock shaft 14 which I term the feed travel shaft and the up and down movement of the feed dog is btained from a rock shaft 15 which I term t e feed lift shaft. These rock shafts 14"and 15 extend longitudinally within the base 5 and have their right hand ends journaled in bearings formed in a depending lug 16 and their left hand ends journaled 1n bearings formed in a block 17 detachably secured to the left hand end of the base 5 by screws 18--18. Fixed to the outer end of the feed travel shaft 14 is a rock arm 19 and pivotally connecting the outer end of the rock arm and the forward extremit of the feed dog 12 arm 19 extends in a general vertical direction and the link 20 extends in a general horizontal direction, thus upon movement of, the rock arm the link 20 will impart backward'and forward movementsjto the feed dog 12. The feed dog 12 is pivotally connected as at 21 tothe upper end of a substantially vertically dis-l I posed link 22, the lower end of saidlink being pivotally connected as at 23 to the horizontal arm 24 of a bell crank lever 25, the- 30. fixed to the feed lift? shaft 15. In order to maintain the feed surface of the feed dog in a substantially horizontal plane during the feeding movements thereof, I provide a spring 31 which is connected between a 32 on the link 22 and a endent tail 33 fixed to the feed dog. It w1ll,-therefore, be ob-' served that. upon rocking movement of the shaft-1 5 the vertical link 22 will'be bodily raised and lowered and consequently the- \feed dog will be given its up and down movements. By proper timing of the shafts 14 and 15 a 4-wa f eed motion will'be imparted to the fee dog.

g The bell crank lever 25 is pivoted as at 34, I andthls pivot is fixed to ahead 35 securedto the lower end of a guide post 36, said head andpost forming a'vertically movable carrier. The post 36 is mounted for vertical sliding movements in a bore formed in the block 17, and this block is formed with a seat 37 for receiving and limiting the upward movement of the carrier. 1 This car-- rier is normally held in its highest position by means of a fiat spring 38 the inner end of which is rigidly secured to the base 5 and the free end thereof is disposed under the carrier so as to yieldably hold the latter in its highest position. The upper end of the post projects above the block 17 and carries a air of rearwardly extending arms 39-39 tween which is pivoted as at'40 the work clamp 13. From the foregoing, it will be observed that when the carrier is moved downwardly against the tension of the spring 38, both the feed dog 12 and the work clamp 13 will be correspondingly moved, thus permitting the work presenting mechanism to be depressed as an entirety. In order to so depress the work presenting mechanism, I have :provided an operating lever 41 which is fulcrumed on the base 5 and has one end disposed in contact with the upper face of the head 35., The other end of the lever is adapted to be raised through the a plication of a knee shiftingv device or trea le,-neither of which however is shown in the "drawings. i

7 From the foregoing, it will be observed that when the feed dog ,is elevated to its highest position, the fulcrum .of the bell crank lever 25 is then shifted to the pivot 23 and consequently the last part of the rocking movement of the crank arm 30 will cause the bell crank 25 to be moved dowm wardly about its fulcrum 23 thus lowering the work clamp 13. The parts are so timed that the work clamp is thus lowered prior to the feeding movement of the feed dog. The reverse order of movement willtake place at substantially the time when the feed dog reaches the end of its feeding stroke, thus causing the clamp to engage the fabric and clamp the latter against the foot prior to the time the feeddog begins its downward movement. f

In order to rock the feed travel shaft 14 and the feed lift shaft 15 I provide the main shaft 10 with eccentrics 42 and 43 respectively. A connection rod 44 has its upper end engageable with the eccentric 42 and its lower end pivotally connected asat. 45

to a rock arm 46 fixed tothe rock shaft 14.

A connection rod 47 has its upper end engageable with the eccentric 43 and its lower end pivotally connected as at 48 to a rock arm 49 fixed to the shaft 15. It will be noted thatthe connection rods 44 and 47 are disposed within the post 6 of the machine frame.

The fabric as it is fed past the stitching head is adapted to be intermittently crimped or bent so as to form a node .Which will be positioned in the path. of the needle whereby the latter will, or will not, depending upon the height of the node, enter said node and project a penetrant needle thread loop therethrough. as will hereinafter be more fully described. In' order to provide for this crimping or bending action of the material the presser foot 9 is formed with an opening 50. .The material is upwardly bent or crimped into this opening by means "of a reciprocatory plunger 51 which extends upwar'dly through the feed dog 12 and work clamp 13. This plunger is mounted for vertical sliding movements within a barrel 52 fitted within a bore 53 formed in the end block 17. The lower end of the plunger 51 is formed with a reduced end 54 forming a resultant shoulder 55. The lower end of the barrel 52 is fixed to 9. lug 56and the .reduced end 54 of the plunger extends through an opening 57 formed in 'said lug and threaded onto the lower projecting end thereofv are lock nuts 58. Disposed within the barrel 52 between the shoulder of the plunger and the lug'56 is a coil spring 59 whlch yieldably holds the plunger in its highest position relative to the lug 56. It will be evident that when the barrel is moved upwardly the plunger will be moved therewith, but just as soon as the plunger engages the fabric a resistance to the upward movement of said plunger will take place and the spring 59 'will permit the barrel to continue its movement while the plunger spring 59 is being compressed.

The plunger 51 is vertically reciprocated through the medium of a rock shaft 60 which extends longitudinally of the base 5.

speed of rotation of the cam roller shaft 70 The rock shaft 60 is provided with a crank arm 61 which is connected by a link 62 to the lug 56; The rock shaft 60 is located beg low the plunger and the link 62 extends substantially vertically .when the plunger is at its highest position. I I

For the purpose of bodily varyingthe vertical position of, reciprocation of the plunger, I have supported the rock' shaft 60 for vertical bodily movements and to this end I have journaled the shaft in bearings formed in a cradle or rocking frame which I have designated as a .whole by thereference numeral 63. This cradle includes 'a rock shaft 64 having one end supported for rocking movements on a pin 65 carried by the end wall of the base 5 and its other end: journaled in the depending lug 16 of said base. The rock shaft 64 is provided with sleeve 69 is a face cam 72 and this cam is formed on its upper face with a curved surface containing diametrically opposed high points 7 3-73 and diametrically opposed low tends upwardly through the post 6 of the frame and is driven from the main shaft 10 by a gear coupling 75 which reduces the relative to the main shaft 10 by the ratio 1 to '4. This gear coupling 75 includes a spiral gear 75 which is fixed to the cam roller shaft through the medium of a collar and a spiral gear 75 which is fixed to the main shaft 10. The cam roller shaft extends through a concentric opening in the cam 7 2 and fixed to the shaft directly above the cam face of said cam is a sleeve 76 which carries a cam roller 77 engageable with the cam face of the cam. The upper end of the cam roller shaft.70 above the gear coupling 75 is mounted within a sleeve 78 which has threaded, engagement 3 with an opening formedin a plate 79 which is detachably points 74-74. The cam roller shaft 70 exsecured to the upper end of the frame. The

lower end of the sleeve rests on the collar 7 5 of the gear coupling. Fixed" to the upper end of the sleeve 78 is a knurled head 80 by means of which the vertical position of the sleeve may be adjusted. A screw 81 is threaded into the upper end ofthe cam roller shaft 70 and the head of this screw bears against the upper end of the sleeve 78 and thereby retains the cam roller shaft 70 er 77, thus elevating the plunger shaft 60,

eeve 78. 'In other words, the collar 75 prevents upward movement" of the cam'roller shaft 70 relative to thesleeve '78, and the screw 81 prevents downward movement of the cam roller: shaft relative to said sleeve. Thus upon vertical movement of the sleeve 7 i 78, the cam roller shaft 70 will be correspondingly moved. Downwardmovement of the cam roller shaft.7O causes the cradle 63 to be rocked through the medium of the rollthe latter being'moved upwardly in an are .about the pivot of the cradle. The upward bodily movement of the shaft.60 will in turn bodily elevate the position of reciprocation of the plunger through the medium of the rock arm 61, link 62 and lug 56, as diagrammatically shown in Figure 20. Upward adjustment of the cam roller shaft 70 will lower the position of the shaft 60 as diagrammatically shown in Figure 19.

The plunger shaft 60 is rocked in the sup porting cradle or frame 63 by therock arm 49, the outer end of which is pivotally connected as at 49 to the upper end of a substantially vertically disposed link 49, the lower end of the link being pivotally connected as at 49 to a rock arm 60 fixed to the plunger shaft 60. Inasmuch as the cam 72 is' provided with two high points and two low points, and the main shaft makes four complete revolutions to one of the 0am roller shaft 70, it follows that the bodily ppsition of reciprocation of the plunger will elevated. durlng every other revolution of the main shaft, and that the plunger will be reciprocated when the plunger rock shaft 60 l is in its high position and also when it is in its low position.v

The plate 79 IS'SlOttBd to form a clamp for the sleeve 78, and a screw 7 9 cooperates with the clamp to lock the sleeve against turning.

' In order to turn the sleeve it is necessary to first release the clamp. The proper bodily position of reciprocation of the plunger may then be obtained by actuating the sleeve 78 after which the sleeve is clamped against.

further freerotation by'the screw 79, thus permanently fixing or setting the bodily position ofreciprocation of the plunger.

In order to control the depth of needle penetration in the superimposed fabric, I have provided a coil sprng 82.which is disposed between the front walliof the base. 5 of the frame and a rock arm 83 fixed to the cradle 63. The rock arm 83 is formed with a rectangular slot 84 and dis osed in this a slot is an angular sleeve 85 havmga threadbolt 87 passes.

' against downwardmovement"relative to the; the front wall. The rear end of the angular numeral 90 and includes a base layer 91 and a superimposed layer 92, the latter being in this case anintegral part of the base layer and forming a-hem or fell. The marginal edge portion of thesuperimposed layer 92 is provided with a binding 93 and this bindin is secured to the superimposed layer by a ine of through-and-through stitches 94.

- The superimposed layer 92 is secured to the In' these drawbase layer. 91 by'a line of stitches .allof which penetrate the superimposed layer. At intervals, preferabl regular intervals,for regular s acing t ereof," certain of the stitches w ich' penetrate the superimposed the u per facebf the base layer 91. The stitches w Ichlayer 92 also pass into and out o penetratethe superimposed layer only are tightly set whereas-those stitches which also pass into and out'of the upper face of the ase layer are loosely set. As a result, a

sufficiently tight seam for all ractical purposes is created and the formation of dimples i or puckers on the under or fair side of the base'layer will be prevented. These stitches are preferably formed through the instrumentallties of aneedle 95 and a',co--

shown operating book 96', the latter bein in Fi 1 of the drawings. The nee 1e 95 is curve and oscillates about a horizontal axis disposed directly above the of the needle in the fabric.

int of entrance. he needle oscillates in a vertical plane disposed at an an 10 to the general lineof the seam andin t is instance I have "shown the needle as being disposed at an angle of 45. The needle enters the superimposed layer 92 'at a point.

adjacent theline of stitches 94 and under the marginal edge of the binding which is,

said stitches. '94; The needle secured by thread 96 is formed into. "a ser1es of loose penetrant loops 97 and also mto a series of tightpenetrant loops 98, the latter being 9.1- m o I ternately disposed with respect to the loops 97. The loops 97 pass through the superimposed layer92 and thence into and out of the upper face of the base'layer 9 1, and

the bite of each loopro'ects above the face of said base layer. T e. oops 98 do not pass into the base layer 91- but referably terminate between the upper an lower faces of the superimposed la er 92,. These loops are.

keyed, thatis locke by a bobbin thread 99. The specific seam above described forms the clamp means;

subject matter of my copending application Ser. 190,685,174 filed January 9, 1924.

' The presser foot 9 is rigidly but detachably secured to the head 8 by means of screws 100-100. This foot is, of course, disposed directly above the feed dog 12 and the work 13 and the foot is formed with the opemn to receive the node of fabric forme by the plunger 51. The horizontal axis of the needle is disposed directl above and in alignment with the lon itud1- nal axis of the plunger 51. The opemng 50 is a art of a centrally disposed and rearwardl y extending fabric guiding slot 102, which extends in theline of feed to a point beyond the plunger 51,.the rear or inner end of the guiding slot 102 terminating in rear of the lunger 51 in an offset portion 103. A needle guide 104 which is formed of hardened steel is detachably secured to the foot by a screw 105 and this guide is formed with a guiding recess 106 for the needle 95. This guide is attached to that portion of the foot on the right-hand side of the fabric guiding slot 102 and one end thereof terminates in a.combined edge guide and lifting device 107. This combined edge guide and lifting device 107 is employed .for the purpose of engaging the margin of the bindin 103 and elevating the marginal edge thereo above the path of the needle whereby the latter "may penetrate the superimposed layer92 at a point close; to the line of through-a'nd-throngh stitches 94, thus permittin the marginal edge portion of the 7 body to utimately cover or conceal the con- 108 is a shelf 109 w the marginal. edge V cation of the yoke shaped needle bar 110 tion is pivoted to the lower end of necting 'needlethread 96. Secured to the left hand side of the Er'esser foot by a screw ich serves to support portion of the'superimposed layer 92 above the path of the needle thereby preventing'the needle from "penetrating the superimposed layer except at the original point of entrance, viz: ad'acent the marginal edge of the binfiidg. 'I he shelf 109 furthermore supports the. superimposed layer-92 above the path of reciprodoes not at any time engagesaid superimposed layer 92. I i

The needle 95 is centrally carried by a pivoted as at 111 at ,the extremities of its limbs on the head 8. One of the needle bar limbs has a lever prolongation and this lever prolongaa link 112 with a wrist pin 113 of a counterwei hted crank arm7114 carried by a jack sha 115 which is jonrnaled in the head 8 and is operated from the' mainfshaft 10 by a 1-to-1 ear coupling 115'. The axis of the needle ar is disposed at an angle of 45 relative to the line of feed and consequently the nee tightv and loose plunger 51 so that said plunger than the spring much as I employ a 1-to-1 gear couplin 115",

' the needle will make one complete osci ation to every rotation of the main shaft 10. The

needle cooperates with the hook 96 to form a series of lock stitches. This hook is mounted on the shaft 116 and'this shaft is driven. in a 2-to-1 relation relative to the .rotation of the jack shaft 115 through the medium of beveled gears 117, vertical shaft 118 and spiral gear coupling 119, the gears of which coupling are res ectivel carried by the 'ack shaft 115 and t e'vertical shaft 118. Thus the hook will be rotated twice for each oscillation of the needle and will cooperate with the needle in a manner well known to those skilled in this art.

' A take-up arm 120 for the needle thread is fixed to a sleeve or hub- 121 which is jonr naled on a horizontal pin $122 in the head 8.

A rock arm 123 is also fixed to the sleeve or B5 hub 121 and has sliding engagement with a blocli124 which is' pivotally connected as at 125 to a laterally extending rigid arm 126 of the link 112. The take-up arm 120 is thus given a differential rate of motion in an appropriately timed relation to the needle oscillations. In the cyclic operation, the take-up lever is given a rapid rise, a slow descent and an extended dwell in its lowered position.

The needle thread 96 is led from the supply to a stationary thread guide 127 fixed to the head 8, thence through tension disks 128'and 129 respectively of anintermittent tension device, through a stationary guide 130,

thence through the spring tension 131,

thence throng a'guide 132 formed in the end of the take-up arm 120 and thence to the needle 95.

The intermittent tension device acts on the needle thread 96 so as to form alternatestitches as'hereinbefore ascribed. The tension disks 128 and 129 i are mounted on a horizontal rod 133 mounted to slide longitudinally in a bore 134' formed in the head 8. This rod is preferably held against rotary by, a screw 135 having threadedengagement with the head 8 and operating in a longitudinal egroove 136 formed in said rod. Form 128 and 129 are disposed between the frame 8,and said flange 137. The front end ofthe rod is threaded and is provided witha nut Between the disk 129 and the nut 138 is a light coil 8 ring 139. The. rod 133 extends rearwa formed with a threaded end portion 140 havln a nut .141 threaded therwn. Interposed tween the frame 8 and the nut 141 is a heavy .co1l spr1'ng142 which has considerably more tensional strength or pressure 139; The spring 142 urges the rod 143 rearwardly and causes the flange onthe front end of the rod 133 is a flange or shoulder 137 and the two disks movement, however,

y of the frame 8' and is or shoulder 137 to force the disks against each other and against the frame 8. Thus in'. the normal position of the vparts, the needle thread is under the heavy tension of the spr' 142, and the light spring 139 has ractlca y no effect on the thread; The rod 33 is ada ted to be moved forwardly so as to relieve t e disksof the heavy pressure exagainst said disks and needle t erted by the spring 142, but permits the spring 139 to still exert its light tension read pass ing therebetween. In order to intermittentlyactuate therod 133 andthereby intermitshaft 144 is such that the high point 147 will tap actuate the tension rod 133 durin alternateoscillations of the needle. Imme iatel following the casting. off of the needle t ead loop from the point of the hook 96- the takeuparm120 begins its upward movement for the purpose of taking up slack in said needle thread and thereb setting the stitch. In view-of the fact t at the cam 147 actuates the tension release during the settin of every other stitch, it follows that the a terpate stitcheswill be loosely and tightly set.

Occasionally it may be desired to form a seam in which all ofthe stitches are looselyv set. To this end I have providedthe shaft 144 with a surface cam 148 which is disposed adjacent the cam 146. The surface cam 148 is vided with a diametrically opposed p nts 149-149. The shaft 144 is ted to be shifted endwise' so as toposition either'of-the cams 146,01 148 into enment with the tension rod 133. In or- Y to retain the shaft144 in either of its previously mentioned set positions, I have provided a hook-shaped latch 150 which is pivoted at 151 to the head 8, the latch bein adapted to enga e in either of the periphera grooves ,152 an 153 formed in the shaft 144. The grooves 152 and. 153 are spaced apart a .distanceequal to the distance between the centers of the cams 146 and 148.

I in the groove 152, the cam 146 will be As a resu'lt,'when the latch 150 is positioned cated in 000 rative relation to the tension 'rod- 133,111 when the latch 150 engages in the groove 153, the. cam-148' will be located coo rative position to the tension rod e worm 1 whichv is fixed to the shaft 144 isof a length suflicient to permit of this endwise adjustment of the r0d 144 with tttt ttt' out disconnecting said worm fromits driving'connection. Therefore, when the cam 148 is positioned to cooperate-with the ten-- sion rod 133, the diametrically high points! 149149 will automatically release the ten"- theseam will be formed of stitches which are each set loosely.-

In the operatlon of the machine,the fabric is positioned in proper sewing relation,

relative to thepresser foot as illustrated in Figures land 13,the edge port-ion of'the super-imposed layer 92 belng guided within treme edge portion which is covered by the binding 93 being held above the plunger and out of. engagement therewith by means of the shelf 109 of the Presser-foot. -The mart ginal edge portion of the binding 93 is slightly elevated by the lifting device107 which is attached to the Presser-foot. This the channel 1020f the resser-foot, the ex]- lifting device serves to lift the marginaledge portion of said binding so as to permit the needle point to enter thereunder and close to the line of the through-and-throug'h stitches 94. Inasmuch as the superimposed layer is supported above the path of the needle\ reciprocation by means of the shelf 109, the needle will always netrate said superim' osed layer. It is desirable to have the nee e alternately penetrate the basev layer 91 and this is accomplishedb'y means of the plunger 51 which causes said base layer to be alternately crimped for penemo tration by theneedle during alternate reciprocations thereof. This alternate crimping or bendi about by't e following:', When-.eitherof he cradle 63 will plunger rock shaft 60. The highest-position i h points 73 of the cam 72 is en ged by the roller 77, the

rocked thus elevating the of the base layer 91 is brought of the plunger rock shaft 60 through the medium of t e high'points 73 above noted,

determines theposition of the base layer relative to the path of needle travel. Therefore, this determines the depth of needle] enetration in the base layer.

of movement for adjustment of the bodily position of reciprocation of the plunger,-

thus providing a plunger mechanism which will take care of fabrics of different weights. high point of the cam and approaches the low point 74 thereof the cradle 63 will be returned, that is, rocked, thro h caniwill tend to move upwar y and maintain its contact relation witl1' the roller '77. This upward movement of the cam due I The cam 2 1s cutso as to produce an extreme limit As the cam roller 77 leaves the "the action ofv the coil springl'82and t e '12.";

to the rocking movement of the cradle 63' necessarily lowers the plunger rock shaft 60 and censequently the lowest verticalosition of reciprocation of the plunger is o tained.

1b sion during the setting of all stitches. Thus '1 i to the length of one stitch base layer by reason of the high point '7 3 only This'extreme low position, however, may be easily regulated through the medium of the rod 87 and the sleeve 85 which engage with the rock arm 83 of the cradle and thereby of reciprocation of the needle. Thus when each high point 73 ofthe cam engages the cam roller 77 thebase layer 91 is upwardly crimped andpositioned in the path ofreciprocation of the needle, the needle thus penetrating not only the superimposed layer.

' ut also entering and emerging from the same face of the base layer. This stitch is loosely set due to the action of the intermittent tension releasing mechanism. The fabric is then fed rearwardly a distance equal and the needle in its next movement penetrates only the superimposed layer 92, the needle escaping the cam leaving the cam roller, and the rocking movement of the cradle 63 bein .limited by the proper adjustment of the rod 8 Thus the plunger is elevated during every other cycle, that is, during the formation of every other stitch. The parts are so timed that when the needle thread of the stitch which penetrates the superimposed layer 92 only \IS 'beingcast from the hook, the cam147 of the tension release is ineffective and consescope of my invention.

quently the'stitch-is tightly set. 1

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and I claim: 1. In a sewing machine, the -combination with a reciprocatory threaded 'needle and a complemental stitch forming mechanism for forming a series of connected stitches,- said 3 mechanism including a rotary hook and a.

' hook, a tension device for the needle thread,"

threaded bobbin, of means for rotating said and means respectively releasing and restor ing said tension device automatically during the formation of alternate stitches whereby said connected stitcheswill be alternately set loose and tight.

2. In a sewing machine, the combinationwith a reciprocatory-threaded needle and a complemental stitch forming mechanism, for forming a series of connected stitches, ofa tension device for the needle thread, includ ing relatively weak and strong pressure springs, the strong pressure spring normally the i 3 of serving to tension the needle' thread, and

means for respectively releasing and restoring said strong pressure spring during the formationofalternate stitches whereb said connected stitches will be alternate y set loose andtight.

3. In a blind stitch sewing machine, the I combination with a reciprocatory threaded needle operating in a constant path and a complemental stitch forming mechanism for forming a series of connected stitches, of.-

a" work resenting mechanism operating below sa1 stitch forming mechanism, a vertically'movable plunger operating below the a work material, means for moving the plunger upwardly to bend the material in ad,- vance of and for alternate needle penetrations, a tension device for the needle thread,

tension device in timed relation only to said alternate needle penetrations.

1. In a blind stitch sewing machine, the

.and means for automatically releasing said,

combination with a reciprocatory threaded needle operating in a constant path and a complemental stitch forming mechanism for forming a series of connected stitches, of a work presenting mechanism operating below said stitch forming mechanism, a constantly reciprocatory plunger operating below the material, means for bodily elevating the plunger without disturbi g its reciprocatory movements to bend the material inadvance of and for alternate needle penetrations, a tension device for the needle thread, and means for automatically releasing said tenternate needle penetrations.

5. In a sewing machine, the combination with a frame having a bore, of a rod mounted inv said bore for trelative longitudinal movements and provided with a shoulder, of

.sion device in timed relation only to said ala pair of tension discs mounted on the rodbetween the shoulder and the frame, interposed between the frame and the rod for yieldingly clamping said discs between for intermittently moving said rod against the tension of said spring to release saidpredetermined adjustable means for in discs, intermittently moving said. rod againstthe tension of said spring comprising a lon itudinally adjustable cam-shaft, a plurality of differently timed cams carried thereby and respectivel adapted for engagement with the end 0 said rod in difieren't positions of adjustment of said cam-shaft, and means'for retaining said shaft in an adjusted position.

6. In a sewing" machine, the combination with a frame having a bore, of a rod mounted in said bore for relative longitudinal movements and provided with a shoulder,

of a pairof tension discs mounted on the.

rod between the shoulder and the frame, a spring interposed a spring the frame and the shoulder of the rod, means between the frame and the "9 rod for yieldingly clamping said discs between the frame and the'shoulder of the rod, means for intermittently moving said rod against the tension of said ring to release said discs, predetermined a justable means I for intermittently moving said rod against 'the tension of said spring, com using a longitudinally adjustab e cam-sha a pluraht'y of differently timed cams carried thereby and respectively adapted for engagement with the end of said rod in different positions of adjustment of said cam-shaft,

said shaft being formed with spaced annu- -lar. recesses, and means for retaining said shaft in an adjustedposition comprising a keeper pivoted on the frameand engageable in a registering recess. P

7. In a blind stitch combination with a reclprocatory threaded needle operating in a. constant path and a complemental stitch forming mechanism for forming aseries of connected stltches, of a work presenting mechanism including a presser foot havinimeans for supporting the fell above the ase layer,-, whereby the needle will penetrate said fell during each reciprocation, means for elevating the base layer into the path and in advance of only alternate needle reciprocations whereby said needle will alternately penetrate the. fell and'thefclland base layer, a tension device for the needle thread, and means for auto-- matically releasing said tension device duringthe formation of each stitch penetrating fell, and an edge lifting device secured to the body fportion for, raising the m rginal portion 0 the-binding for permitting the needle to pass through the fell directly under the raised portion of the binding, a feeding mechanism cooperating with the foot to" feed the material past said stitch forming mechanism, a vertically movable plun er operating below the presser foot, means or moving the plunger upwardl to bend the body fabric in advance of an for predeter mined needle penetrations whereby the needle during one reciprocation will enter the fell only and during another reciprocation will enter both the fell and the body fabric,1a tension device for the needle thread, I and means" for releasing and restoring said tension device automatically during the formation of the stitches whereby redetermined connected stitches will tight respectively.

felling machine, the

be set oose and 9. In a blind stitch sewing mama 01% am a o o I l j ing seams, the combination with a reclprocatory threaded needle-and a complemental' stitch forming mechanism for forming a series of connected stitches, of a presser foot disposed below said needle and comprising a body portion having a rearwardly extending slot for guiding a previously bound fell, and an edge lifting portion for ralsing the marginal portion of the binding for permitting the needle to pass j through the fell directly under the raised a,

portion ofthe binding, a feeding mechanism cooperating with the foot to feed the material past said stitch forming mechanism, a vertically movable plunger operating below the presser foot, means for moving the plunger upwardly to bend the body fabric device secured'to the body i in advance of and for predetermined needle penetrations whereby the needle during one reciprocation will enter the fell only and duringlanother reciprocation will enter both and the body fabric, a tension dethe fel vice for the needle thread, and means for"- automatically releasing said tension during the formation of the stitches-connecting the fell and the body fabric and for automatically restoring the tension. during the formatioln of the stitches passing through the fell on y. r

10. In a blindstitch sewing machine for felling seams, the combination witha reciprocatory threaded needle and a comple mental stitch forming mechanism for forming a series of connectedstitches, of a resser foot disposed below said needle an comprising a body portion having a rearwardly extending slot for giiiding a previously bound fell, and an edge lifting device secured to the body portion for raising the marginal portion of the 'binding for; permittmg the needle to passthrough the fell directly under the raised portion of the binding, a feeding mechanism cooperating with the foot to feed the material past said stitch forming mechanism, a vertically movable means for moving the plunger upwardly to bend the body fabric in advance of and for alternate needle penetrations" whereby the tion will enter both ,thefell and the bod plunger operating below the" presser foot,

fabric, a tension device for. the needle threa a and means for respectively releasing and restoring said tension device automatically during the formation of alternate stitches whereb said connected stitches will be'alternate y set loose and tight.

ing a body portion having'a rearwardly ex- L 11. In a blind stitch sewing machinefor felling seams, the combination with a retending slot for guiding a previously bound ,fell, and an edge lifting device secured to the body portion for raising the marginal portion of the binding for permittingthe needle to pass through the fell directly under the raised portion of the binding, a feeding mechanism cooperating with the foot to feed the material past said stitch forming mocha:

' nism, a vertically movable plunger operating below the presser foot, means for moving the plunger upwardly to bend the body fabric in advance of and for alternate needle penetrations whereby the needle during one reciprocation will enter the fell only and during the next reciprocation will enter both the fell and the body fabric, a tension device for the needle thread, and means for automatically releasing said tension during the formation of the stitches connecting the fell and the body fabric and for automatically re: storing the tension during the formation of the stitches passing through the fell only.

In testimony whereof I hereunto aflix my signature.

CHARLES W. MUELLER.

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