US1408185A - Looper-thread-controlling mechanism for sewing machines - Google Patents

Description

G. S. GATCHELL. LOOPER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES. APPLICATION FILED FEB. 6,19 19 1,40 ,1 5, I mm Feb. 28, 1922.

3 SHEETS-SHEET l- INVENTOR WlTNESSES:

G. S. GATCHELL.

LOOPER THREAD CONTROLLING MECHANISM F0 R SEWING MACHINES. APPLICATION FILED mm, 1919.

1,408,1 5, Patented Feb. 28, 1922.

3 SHEETS-SHEET 2.

WITNESSES:

Y/ W v ORNEY I e. s. GATCHELL; LOOP ER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED FEB--B, I919.

3 SHEETS- SHEET 3.

YatenteMieb. 28, 1922.

INVENTOR HLW 7 WITNESSES:

ATTORNEY UNITED s'rArp PATENT OFFICE.

GEORGE s. GATCHELL, or ROSELLE PARK, NEW a'nnsny, ASSIGNOR. To THE SING MANUFACTURING COMPANY, A CORPORATION OFYNEW JERSE LOOPER-THREAfD-CONTROLLING IJZECHANISM FOR SEWING- IMACHINES,

Application filed February 6, 1919, Serial No. 275,296.

To all whom it may concern:

Be it known that I, Gnonen S. Gn'rorrnnn,

a citizen of the United States, residing at Roselle Park, in the county of Union and State of'N'ew Jersey, have invented certain new and useful Improvements in Looper- 'lhread-Controlling Mechanisms for Sewing Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

In the formation of chain-stitch seams by machines of the well known type embodying a threaded vlooper in cooperation with one or more reciprocating needles, as disclosed,

for example, in U. S. patents to Muther etaL, No. 299,569 (one needle) and No. 583,- 415 (two needles), and Molyneux No. 1,- 266,036, (four needles), it is desirable from the standpoint of good sewing that the needle-loops be fully drawn up to the. under surface of the work regardless of variations in the length of stitch or character of work being sewed.

needle-loops at the under side of the seam be uniform under varying sewing condi tions. p

The looper of machines of the type under consideration commonly passes a loop of looper-thread through one or more needleloops and then presents the looper-loop for entry by the succeeding needle-loop or loops which, in turn, is or are entered by the looper carrying a new looper-loop, and so on. Vhenthe needle-loops are drawn up, the looper-thread is drawn into its usual circuitous or zigzag course through and about the needle-loops, and it will thus be clear to those skilled in the art that, other conditions being equal, a greater length of looper-thread will be required for a long stitch than for a short stitch.

In operating machines of the above type,. it is customary at times to chain off, that v In other words, it is desirable that the appearance of the looper-thread and ,needlethread take-up means.

of an elastic nature and the feeding element WlllCll engages the chain in rear of the sew ing point will stretch the chain'thus allowing the stitches being formed to crowd more closely together on the usual stitch-supporting tongue or tongues in the throat-platc, than they would if formed in material.

Adjustment of theneedletlnead tension device will have a greater or less effect upon the degree to which the needle-loops are drawn up by the needle-thread take-up mechanism and, while it is desirable to adjust theneedle-thread controlling mechanism so that theneedle-loops will be fully drawn,

up to the under surface of the work, itis a fact that if for any reason these loops are notfully drawn up, less looper-thread is required per stitch. I i i Thus the amount of looper-thread use per stitch depends upon the stitch length and whether the machine is sewing in ma terial or chaining off, as well as upon other more or less variable conditions, such as the adjustment of the thread tension and It hasheretofore been common to provide machines of the type referred to with looper thread controlling mechanism comprising an intermittently acting thread-nipper, a pulloff on the supply side of the nipper and a take-up or slack-thread controller on. the I work or looper side of the nipper. In these machines, the looper starts forward to enter the needle-loop or loops, the looperthread is supposed to be free from slack and the take-up is designedlto have sufficient actron on the looper-thread to prevent the formation of slack as the looper advances, I

thereby overcoming the tendency of the looper-thread to buckle in front of the eye of the looper. As soon as the looperbeak hasenter ed the needle-loop or" loops,

the nipper is opened, and as the looper'advances to the end of its stroke it draws through the nipper an amount of looperthread sufficient for the formation of the next stitch; this amount having been previeuslv measured from the supply by the mil-off. As the Mr retracts the needles, 1 i descend in the customary manner, pass1ngdown beside their previously formed, loops on the looper and entering the looper-loop.

After the looper has shed the needle-loop ioo or loops and nears the end of its retracting or chaining off.

stroke, the needle-thread take-up mechanism draws up or tightens the needle-loop or loopswh'i'ch' thereupon absorb or draw into the stitchthei supply of slack looper thread afforded by the looper Thus, when the looperreaches the end of its retracting stroke, the looper-thread is free from slack.

While itis possible to sew under these con ditions, the results from a practical standpoint are not fully satisfactory, inasmuch as the usual variations in sewing conditions are'not taken care of. For eXamp'le,"when the feed is shortened, or when chaining off,

less looper-thread is required perstitch, and the f amount of looper-thread drawn past .the nipper by the advancing looper is more than enough for the stitch being formed. As a result, there is slack in the looperthread after the looper has reached the end ofitsretracting stroke and, as the looper starts forward, the take-up does not have .sufficient action to absorb this slack-thread and, in addition, take care of the slack thread normally given up by the looper during the, first part of its advancing stroke. Thus, there is danger that the looper-thread will buekle'in front of the eye of the looper and get on the wrong or front side of the looper point, thus causing thread-breakage or skipping of stitches.

In. other words, the looper-thread controllin mechanisms" of the prior art will properly" control the looper thread only under-one fixed set ofconditions. If, then, the feed is shortened or an attempt is made to chain off, the machine is very apt to break thread or skip stitches. On the other hand, if the feed is lengthened, the fixed amount ofslack looper-thread afforded per stitclr will not permit the needle-loops to be fullydrawnup and the appearance of the stitch will be unsatisfactory.

Further objectsof the inventioniwill ap; pear'from the following description and claims.

To the" attainment of the ends in view, the stroke of the looper is preferably made sufficient to draw enough looper-thread through the nipper for maximum requirements, that is, when sewing the longest stitches for which the machine is adapted, and the pull-offis designed to be-eapable-of measuring this amount of threadfrom the sup ply. The nipper, instead of being timed as heretofore "to release the looper thread only during the last part of the advancing stroke of the-looper, is further timed to release the looper-thread momentarily just after the needle-loops have been drawn up, which usually occurs at the time the loopers are fully down and the looper fully retracted.

In the present instance the relation of the pull-off to the nipper is a feature of great, importance; the pull-off being preferably so timed that it is pulling thelooper-thread rather rapidly from the supply atthe time i of the momentary release of the looperthread by the nipvper. The result is that whatever slackth'read there may be between the nipper and the work, as the looper is just starting forward, will be quickly pulled back through the nipper by the pull-off before the looper has travelled a material distance. In other words, any surplus or leftover looper-thread from the last stitch forming operation will be drawn back tothe supply side of the nipper by the pull-off, prior to the next stitch-forming operation. .Thus the looper-thread will be free from slack as the looper advances, whether or not the supply of looper-thread pulled forwardly through the nipper is fully absorbed in the last stitch.

The invention will be more particularly explained in connection with the accompanying drawings in which Fig. 1 is a left side elevation of a machine embodying the invention. Fig. l is a perspective View of a structural detail of the looper-driving mechanism. Fig. 2 is a horizontal section through the standard of the machine at an elevation above the work-arm, showing thelatter inplan. Fig. 3 is a plan view of the throat-plate and feet -dogs. Fig. 4 is a diagram illustrating the relative timing of the. needle, looper, looper thread take-up, looperthread pull-off and looper-thread nippjer. Figs. 5, 5, 5 and 5 illustrate the positions of the pull-off cam, nipper-cam,take-up cam and stitclrforming implements, respectively,

at the period of the cycle when'the needles Y are fully down. Figs. 6, 6*, 6" and 6 are simi.- lar views at the period whenthe needles are rising aftenthe advancing looper has entered the needle-loops. Figs. 7, 7h 7, and

7 are similar 'views at. the period ofthe cycle when the needles are up and the looper is at the end of its advancing stroke. Fig. 8 is a detail perspective of the supporting bracket for the ta re-up thread-guides and the nipper-springs and Figs. 9 and 10 are plan and longitudinal sectional views seam made by the machine.

While the invention is susceptible of em of the end of the looper-shaft.

bodiment in chain-stitch machines generally, irrespective of the number of needles employed or the type of the machine frame, I have chosen for the purpose of thisdisclosure to embody it in the four-needle, singlelooper feed-up-the-arm machine disclosed in my copending application Serial No. 185,

14:6, filed August 10, 1917.

As more fully disclosed in said copending application, the machineframe comprises the base 1 from which rises a hollow standard 2, carrying the bracket-arm 3 terminating in the head 4 within which are mounted the usual reciprocating needle-bar 5 and presser-bar 6. In the present instance, the needle-bar 5 carries four needles 7 and the presser-bar 6 carries the presser-foot 8.

Supported at its rearward end by the standard 2 is the hollow work-supporting arm 9 carrying at its forward or free end a throatplate 10 and end-cap 11 within which is housedthe threaded looper 12. The looper 12 is mounted on the forward end of the looper-shaft 13 extending within and longitudinally of the-work-arm 9 and receiving oscillatory movements from an eccentric 1 1 on the main-shaft 15 through a pitman 16 and crank 17. Endwise sliding movements are imparted to the looper-shaft by means of an eccentric 18 which is embraced by the strapped end of a pitman 18 the opposite end of which is connected to the upstanding arm 19 of a rock-lever fulcrumed upon but rocking independently of the shaft 20. The depending arm. 21 of said rock-lever is connected by a link 22 to a ball 23 at the rear The eccentrics 11 and 18 on the main-shaft thus operate to impart the usual endwise reciprocatory and sidewise movements to the looper.

The needles 7 and looper 12 cooperate in the usual manner common to machines of this type to form the seam illustrated in Figs. 9 and 10 wherein the abuttededges of material a, a are shown as being penetrated by the needle-loops Z2 which at the under side of the work are concatenated with the looper-thread c in a well known manner.

The feeding mechanism may be of any usual type but is preferably constructed substantially in accordance with the disclosure of my said copending application. The

imparted to the feed-bars by means of the the slotted feed rocker- arms 33 and 34 actuadjustable link connections 31 and 32 with 1' ated by means of the pitman connection 35 with the main-shaft. It will be noted that.

the link 32 may be adjusted in the rockerarm*3t' by a treadle connection, while the machine is in operation; the treadle connection comprising a chain 36, lever 37, 37 pivoted at 37*, a spring 38 and link 39. The

main feed may be adjusted by shifting the rear end of the link 31 along the slotted feed-rocker 33, as will be readily understood.

Referring to Fig. 3 it will be seen that the I main feed-dog 25 includes two sections 25 which are directly in rear of the usual stitch-supporting tongues 40 on the throatplate 10. The feed sections 25 operate to engage the stitched seam and feed it away from the needles. When chaining off the feed-sections 25 engage the chain and pull it off of the tongues 40 on which it is formed.

The machine is equipped with needlethread take-up cams 411 which take up or tighten the needle-loops as they are shed from the looper and control slack in the thread-nipping devices has beenmodified in certain important particulars as will be hereinafter explained. Journaled within 7 and crosswise of the work-supporting arm 9 is a shaft 12 carrying a gear 43 which meshes with a gear 44 turning upon the fixed studshaft 45; the gear 44 meshing with the driving gear 4L6 on the main-shaft 15. The gear ratios are so chosen that the shaft 42 is driven at the same speed as the main-shaft.

Mounted on the shaft e2 are thepull-ofi and take-up cams 17 and 48, respectively, and the nipperactuating cam d9. The takeup cam comprises a pair of spaced cam-disks between which is supported the usual castf oii 50. Mounted on the bracket '56 at 51 is the thread-guiding fork 51, the tines of which are apertured at 52is provided to" present the looper-thread to the action of the take-up cam. The pull-ofi cam 17 c0- operates in a similar manner with the castoff wire-55 and the thread-guiding fork 53, the tines ofwhich are apertured at 54. The

nippenoperating cam 49 acts upon a pair of superposed nipper-springs 55 carried by the bracket 56 which supports the thread-guid ing fork 51.

The looper-thread travels its, usual course from one of the tension devices 6 on top of the bracket-arm. down through the tube57, through the guiding apertures 54 of the pull-off fork 53, thence between the nipper- :trated in Figs. 4 to '7, inclusive.

springs 55 and through the apertures 52 0t theitaker-upi fork '51, thence into the thread receiving slit 58 extendinglengthwise of the work-arm, and out through the guide 59 at tl1e-front end of the work-arm. :From the the looper-thread by the hump.- (iO, Fig. 7, of

the camylfi); at which time the needles arebeginning their descent and the looper is beginning.itsu'eti'actingstroke. With the nippersprings :closed, the take-up 48 rapidly absorbsetheslack-thread afforded by the retractinglooper as the' main-shatt turns from 15 to 90 The came? islfpreferablyformed with a hump 61, Fig. 7 which operates, say, from .80 to 1209 to pull some thread from the sizipply but not enough for the next stitch.

It isde'sirzlble, though not essential, that the pull ofi actzat thistime to permitot' a reductionyot theamplitude ofpull-oil action at a later period ot'the cycle, whereby abrupt or harsh cam actions on the looper-thread may be avoided.v From 90 to 180 the takenp as gives up thread to the looper and to the contracting needle-loops which have been shedby the looper. At 180 the needles are down, theloo fieriis atthe rearend of its strokegandfthe needle-loops shed from the looper are. fully; drawn up, thereby having absorbedinto theestitch-a sup-ply of looperthread given up. by the takeup.

* At.- or slightly before the 180 point, a

rapid pull off action begins, see also Fig. 5, andncontinuesto the250 point, Fig. 4, At, or just after-the beginning. of thisrapid pulloff action', and just as the looper is starting forward, but before itihas travelled amatel'ialxlistance, the nippei springs 55? are permittecl=t0 -openfor a brief interval, from 185 to 205, Fig. 4, so-that the pull-oil l? ma fl draw. back through the 'nipper-springs .55 any slackor unused looper-thread remaining on the looper side otthe nippersprings after the last stitch has been completely" drawn up by the needle-thread take-up devices; This pulling back of the unused or slack looper-thread regardless of theamount thereof, prior to the seizure of the new needle-loops, permlts the next stitch-forming operation to be invariably begun under the same conditions as regards 1 the looper-thread.

In other words they looper-thread will invariably be free from 1 slack as the looper begins its advancing stroke. Thiswillbe so regardless oftheadjustment of the feed or any other of the usual variation 111 sewing COHClIlJIOIlS.

will alwayshave sufficient, action (225 to As. a. result the hump 48 of the; take-up cam 48 255, Fig. 4) to prevent the bucklingotithew I looper-thread in front of the eye ofthe looper and the consequent thread breakage or skipping of stitches. If a partial supply.

of thread for a stitch is not pulled ofi While.

the looper is retreating it will be necessary to pull off a full stitch supply while the main.

shaft turns say from 180 to 255, Figa 4.

The pull-oil curve representing this period would therefore be steeper.

After the pull-off has. measured enouglu threadfrom the supply to meet.the 1naxi-.

mumrequirements for; a new stitch -(260.

and the pull-off rapidly gives up looper thread to the advancing. looper, Fig. 6',

which in travelling to the end of, its strokei,

Fig. 7, pulls through the nip per and takeup enough.loopenthread for the longest stitch which the machine is designed to make; After the looper retracts and the needle-loops are tightened, any, surplus looper-thread is pulled back through the nipper by the pull-off at the period of the cycle when the looper. is substantially at the end oi itsretracting. stroke and beforeit has I travelled a. material distance toward the needles. Although preferable, it is not neces sary that the nipper beclosed afterthe surplus. looper-thread has been pulled back. through the nipper by the pullsoff. The pull-off could be depended upon at'this time; to prevent thebuckling of thelooper-thread in front of the eyeot' the looper as the looper 'advancesto seize the. needle-loops event. the hump lS of the take-up which according to Fig. Lacts upon the looperthread from the 210 point to the 255? point In this I could bedispensed with. lVhilethe-timing is broadly important, the details thereof are susceptible of considerable variationfwithin the scope of theinvention as defined in the claims.

The invention ,notto be understood. therefore, as limited .to the exact construe tion shownand described, asthe principle thereof-1s obviously susceptlble of embodiment in var ous types of chain-stitch machines and in connection with various types of pull-off, take-up, and thread-nipping devices; the specific character and exact timing of suchdevices being unessentialso long as the general relationship and timing is such that the unused looper thread is pulled back to the supply side of the nipper, whereby the next stitch is invariably begun under the same conditions as regards the looper-thread.

Having thus set forth the nature of the invention, what I claim herein is 1. Looper-thread controlling mechanism for sewing machines comprising, one or more needles, a looper, means for imparting advancing and retracting movements to the looper, an intermittently acting thread-nipper, and means for pulling back to the sup ply side of the nipper any slack or unused looper-thread remaining on the work side of the nipper after the stitch has been drawn up.

2. Looper-thread controlling mechanism for sewing machines vcomprising, one or more needles, means for drawing up the needle-loops, a looper, means for imparting advancing and retracting movements to said looper, a looper-thread take-up, a pull-off, an intermittently acting thread-nipper between said take-up and pull-off, said pullofi? being constructed and timed to pull back through the nipper any surplus of looperthread on the take-up side of the nipper after the stitch has been drawn up.

3. Looper-thread controlling mechanism for sewing machines comprising, one or more needles, a looper, means for imparting advancing and retracting movements to said looper, a take-up, a pull-off, an intermittently acting thread-nipper between said take-up and pull-oil, said nipper being timed to open during the latter part of the advancing stroke of the looper to permit the looper to draw enough thread to reach the end of its advancing stroke, said nipper being further timed to open after the stitch has been drawn up and during the thread absorbing action of the pull-off, to permit the pull-off to pull back any slack remaining in the looper-thread prior to the next stitch-forming operation.

4:. In a sewingmachine, in combination, one or more needles, means for drawing up the needle-loops, a thread-carrying looper, a looper-thread take-up, an intermittently actin looper-thread nipper, and a looper thread pull off, the nipper being timed to permit the passage of the looper-thread after the stitch has been drawn up, and the pull-oi? operating to pull back any surplus looper-thread remaining on the looper side of the nipper after the stitch has been drawn up, whereby the looper-thread will be substantially tree from slack at the beginning of the next stitch-forming operation, re-

gardless of variations in sewing conditions.

of the looper at the end of its retracting stroke, and means for pulling back through the nipper any slack looper-thread remaining on the looper side of the nipper at the aforesaid time of release of the looperthread.

6. In a sewing machine, in combination, one or more reciprocating needles, means for drawing up the needle-loops, a thread-carrying looper having reciprocating loop-seizing and shedding movements, an intermittently acting looper-thread nipper, a looper-thread take-up timed to take up the slack of the looper-thread during the first part of the retracting stroke of the looper, a pull-oil for measuring looper-thread from the supply, said nipper being timed to open when the stitch is drawn up and during the action of said pull-off, whereby any slack looper-.

thread on the work side of the nipper will be drawn back through the nipper by the pull-oil? prior to the seizure of the new needle-loop by the looper.

7. In a sewing machine, in combination,

one or more needles, a looper, means for imparting advancing and retracting movements to said looper, a looper-thread takeup, looper-thread nipper, and a looperthread pull-off timed to pull off a partial supply of thread for the next stitch during the retracting stroke of the looper and the remainder of the supply during the advance of the looper, said nipper being timed to release the thread while the pull-ofi is absorbing thread and prior to the seizure of needle-loops by the advancing looper.

In testimony whereof, I have signed my name to this specification.

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