US2662492A - Shoe sewing machine - Google Patents

Description

Dec. 15, 1953 F. c. EASTMAN SHOE SEWING MACHINE 2 Sheets-Sheet 2 Original Filed Jan. 21, 1949 Patented Dec. 15, 1953 2,662,492; SHOE SEW MACH NE Fred C. Eastman, Marblehead, Mass, assignor to. United Shoe Machinery Gorporaticn, Flemin -H t nt. N- J-i a c rucr n of. New Je s Or n l ap ca n. J anuary 1 ,8 3 r a o- 71,990. Divided and this 1952, Serial No. 287 ,89l

(o1. I a-35 6 Cla ms- 1 The present invention relates to improvements in thread finger actuating mechanisms particularly for chain stitch shoe inseam sewing machines of the type disclosed in United States Letters Patent No. 1,108,560, granted August 25, 1914, upon application of Andrew Eppler and No. 1,971,575, granted August 28, 1934, upon application of Alfred B. Morriil, and in a copending application for United States Letters Patent Ser. No. 71,990, filed January 21, 1949, in the name of the present inventor (now Patent No. 2,647,478, granted August 4, 1953) of which latter application the present one is a division.

In machines ofthe type illustrated in the patents referred to, the stitch forming devices com= prise a curved hook needle, a needle looper, a thread measuring finger and an oscillating take-up acting successively during each sewing cycle to give up thread for the formation of each stitch, to tighten and set the stitch by exerting a suddenly applied predetermined tension on the thread and thereafter to draw from the supply sufficient thread for the formation of the succeeding stitch. To enable a predetermined tension to be exerted on the thread a tensioning device is provided comprising a grooved wheel over which the thread passes to the take-up and a friction brake drum is connected to the wheel, a brake shoe engaging the brake drum to resist roe taticn of the wheel. In the patented machines the friction of the brake shoe on the drum exerts only a minor part of the resistance to thread movement past the tensioning device. On ac: count of the weight of the moving parts in the tensioning device, including that of the grooved wheel and the brake drum connected thereto, the resistance offered to sudden thread movement is constituted in major part by inertia, particularly while each stitch is being set by the take-up. The inertia of the tensioning device, therefore, is greater with hard, inflexible work than with soft, pliable work, inasmuch as the snap of the thread is reduced with work having more yielding qualities so that lower intensities of acceleration are imparted to the tensioning device. Furthermore, the degree of elasticity in the thread stretched between the tensioning device and the work has a marked eifect on that part of the thread tension produced by inertia of the tension wheel and brake drum for a like reason. Also, variation in speed of machine operation often causes irregularities in the tension on the thread, compensating devices frequently being employed to increase the tension caused by friction when the sewing operations are slowed down.

application May 15,

As a contributing factor to the cause of irregularities in tension with which each stitch is set in the work, the formation of the stitches and the action of the thread finger in measuring thread for the needle may have marked effects. Insufiicient thread measurement tends to increase the tension and excessive measurement to loosen the stitches.

An important object of the present invention, therefore, is to provide a chain stitched shoe in.- seam sewing machine in which irregularities in action of the thread finger are substantially reduced so that a minimum of variation in tension will be caused when sewing at diiferent speeds with Work having different. physical qualities or when thread having different degrees of elasticity is. employed. Another object is to improve the mechanism for actuating the thread finger of a shoe inseam sewing machine in a manner to eliminate substantially the possibility of the thread sliding in the threaded needle hook while the needle is being withdrawn from the work even though irregularities occur in the operation of one or more of the other stitch forming evice In a rdance with the obj cts n ted. h in? vention is embodied in a shoe inseam sewing mac in havin a main shaft and s itch form n devices actuated her y in ludin a urved hook needle, a looser, a threa fin r. a ake-u an a. thread te si n ns devi i w i m han sm is d d or ac uating the thre d n er to ause th thread fin e t y ld du n it thr ad ivin up mov ment n ordan w th h requ rem n s o each sti c ar i la ly during he ime the thr aded edle is et ac n f om he wo k:- Wit th l s r ed or o h s. m c ani m he h ad fin er m es a o t e ine of k fee to measu r d f o id of e h the t rea fi er t ive up thr ad i, t. Qi eontrel- Th1 a r f e i io 0m emp ates th use. o a i icticn l Joint c in as the yieldin and, ferab he hread fin e m han m s adil ad us a le or hansms he l n h of t t re d asu n s ke.-

Th sc and othe iea u es of t e nvent on cem- Drise t e nove evices. c mbin t ons d ar ansem ts of a s her naitc de r b d and claim d ich; o he wi h the advanta es n he obtaine th re y. ill re d l be nde do s from th ollow de a d s cific i a en connection With the accompanying drawings in which Fig. 1 is a view in right side elevation, partly broken away and in section of a portion of a shoe being operated upon and of the head of a shoe inseam sewing machine embodying the features of the invention;

Fig. 2 is a time chart indicating the relative movements of the thread finger, take-up and needle in the machine of Fig. 1;

Fig. 3 is a detail view in right side elevation of the thread finger and channel guide and their operating mechanisms in the machine;

Fig. 4 is a sectional plan view looking in the direction of the arrow IV in Fig. 3, of the thread finger and channel guide actuating mechanisms;

Fig. 5 is a sectional detail view of a lost motion connection in the thread finger mechanism illustrated in Fig. 3, looking from the front of the machine; and

Fig. 6 is a view in front elevation of the needle, looper, thread finger and channel guide of the machine, shown in operating relationship to a portion of a shoe with a chain stitch seam indicated partly in section.

The shoe machine illustrated in the drawings is constructed and arranged to sew the upper and the welt to the insole of a welt shoe and is provided with a curved hook needle 2, a needle looper 4, a channel guide 5, a take-up 8, a thread finger l0 mounted for swinging movement along the line of feed, welt guide [2 and other stitch forming and work engaging devices similar, except as hereinafter described, to those of the Eppler and Morrill patents above identified. The machine is driven through a driving and stopping mechanism which brings it to rest with the stitch forming devices in a predetermined relationship, indicated in Fig. 1 of the drawings. When brought to rest the needle is retracted from the work and the other stitch forming devices are disengaged from the work to enable it to be removed from the machine.

The stitch forming devices are driven from a main sewing shaft M rotatably mounted in a frame It. As in the prior machine disclosed in the patents referred to, the take-up controls the movements of the thread toward and from the other stitch forming devices during formation of each stitch and tightens the thread to set each stitch after being formed. The purpose of the thread finger is to measure off a length of thread during formation of each stitch in sufficient amount to enable the threaded needle to be retracted from the work without causing slippage through the needle hook, thus avoiding any tendency to abrade or otherwise injure the thread. In measuring each length of thread a thread engaging hook on the thread finger moves along the line of work feed in a direction opposite to that of work feed. If insufiicient thread is measured off, then the thread between the last formed stitch in the work and the needle will be too short so that slippage in the needle hook will take place and excessive tension will be applied to the thread before the needle reaches the end of its retracting stroke. If too great a measurement of the thread occurs in the prior machine, then the thread will become slack and will be likely to become displaced either from engagement with one or more of the stitch forming devices or from proper relation to the work while setting each stitch. Variations in the thickness of the materials operated upon also may influence the sewing operations since the requirements for thread measurement are correspondingly changed. To compensate in part for such variations, the machine of the Eppler patent has a yielding auxiliary take-up.

The machine of the present invention has no yielding auxiliary take-up and the stitch forming and thread handling devices are carefully timed and coordinated with the movements of the thread finger to enable the thread finger to measure thread between the work and the looper needle in a sufficient amount before engagement with the needle to avoid any possibility of the thread sliding in the threaded needle hook while being withdrawn from work of maximum thickness for which the machine is intended to operate. To compensate for the maximum amount of thread measured by the thread finger and to prevent slack thread when operating upon relatively thin work, the illustrated thread finger is actuated yieldingly in giving up thread to the needle so that proper control of the thread in the thread finger will be maintained according to the requirements of each stitch. To these ends, the active stroke of the thread finger is increased beyond that employed in prior machines and the channel guide is bowed outwardly to clear the thread finger during its increased stroke. As more clearly illustrated in Figs. 4 and 5, the thread finger moves directly behind the channel guide at the end of its thread measuring stroke to the dot-dash position of Fig. 4. Also the main take-up is so timed and actuated that it maintains an accurate control of the thread by causing a large number of small increments of thread to be drawn past the thread tensioning device at different times, distributed more or less evenly throughout each sewing cycle, except for that time during which the threaded needle hook is being withdrawn through the work, at which time no thread is drawn past the tensioning device.

The time during which the threaded needle hook is being retracted through the work is indicated in the time chart of Fig. 2 as taking place between a and 200 of main sewing shaft rotation, assuming the position of Fig. 1 as 0 and rotation of the shaft in the direction of the arrow. At this time the Take-Up curve indicates giving up movement greater than is required by the other stitch forming devices so as to provide limited Slack Thread but without releasing all control of the tension. At the time the Thread Finger curve indicates giving up thread to the needle so that both sides of the loop of thread carried by the needle hook through the work have but little tension applied to them. To maintain control of tension in the needle loop without causing excessive slack thread, according to a further feature of the invention, the thread finger during the time of giving up thread to the threaded needle is subject to an indefinite yielding control within the range of movement shown enclosed by the solid and broken lines of the Thread Finger curve.

To enable the thread finger 10 to yield upon the pull of the thread so as to give up thread only when required during the time in each sewing cycle that the threaded needle hook is passing through the work, the mechanism for actuating the thread finger comprises a lost motion connection and a yielding frictional joint in the lost motion connection. The thread finger actuating mechanism is generally similar to that of the Morrill patent, noted above, and comprises an arm forming the thread finger l0 and a thread finger actuating rock shaft It to which the thread finger is fixed, gotatably mounted in a thread finger carrier 20. The channel guide 6 also is rigidly clamped by a bolt 22 to the carrier 20. The thread finger and channel guide carrier are oscillated during each cycle of operations and are moved laterally in the line of feed with the needle while the work is being fed.

The thread finger actuating mechanism imtween two shaft engaging portions of the block, a link 28 pivotally connected between the arm 26 and a cam lever 3t, and a cam on the main sewing shaft l4 having a slot 32 into which a roll on the lever 30 fits.

The lost motion connection in the thread finger actuating mechanism is best shown in Fig. 4 and is arranged between the hub of the arm 28 and the slotted clamp block 24, the limits of the lost motion being determined by a slight angle formed on a relatively straight face 34 within the slot of the block 24, cooperating with a slightly beveled surface on the arm 25. The lost motion connec tion is ineifective during the thread measuring stroke of the thread finger 6 and becomes effective only after the operating mechanism begins to move the thread finger in the opposite direction to release the measured thread. If the requirements of the needle loop, as the threaded needle hook is moving through the work are sufilciently great, the thread finger will be moved simultaneously with the actuating connections. If, however, the thickness of the work is extremely small, the maximum thread measuring position of the thread finger, as shown by the dot-dash lines of Fig. 4, will be retained and the thread finger will not be returned to its starting position until the return limit of lost motion in the actuating connections is reached. Between these two extreme positions the thread finger is moved yieldingly against the action of a frictional joint by the pull of the thread to give up thread to the needle without loss of control in the thread while, at the same time, imparting a minimum tension to the thread engaging the thread finger. For this purpose the frictional joint acts directly on the lost motion connection.

The frictional joint in the actuating connections for maintaining the thread finger yieldingly in its maximum thread measuring position comprises a spring washer 36 (Fig. acting between the clamp block 24 and an upper surface on the thread finger carrier to produce a frictional engagement between the lower surface of the carrier and the thread finger H].

To regulate the thread measuring stroke of the thread finger accurately to the requirements of the machine and to the type of work operated upon, readily adjustable means is provided in the actuating connections for the thread finger. Regulation of the thread finger stroke assists in tightening each previously formed stitch during needle retraction, the loop of thread carried by the needle being tightened sufiiciently to cause the previously formed loop of thread through which the loop carried by the needle passes to be tightened securely about the needle engaging loop. Thus, with thin work and short stitches the thread measuring stroke of the thread finger may be reduced while with thicker work and longer stitches the thread measuring stroke of the thread finger may be increased without affecting the tightness of the previously formed stitches adversely,

slidable in a slot 40 disposed radially of a fulcrum shaft 42 for the lever 30. The pivot 38 is universally connected to the rearward end of the link 28 and is moved upwardly along the slot 40 to increase the stroke of the thread finger and downwardly in the slot to reduce the stroke. To move the pivot 38 along the slot if? the pivot 38 is secured in an upper end of a Cshaped link. 44, the lower end of which is enlarged and provided with a threaded opening within which is engaged the threaded portion of a hollow thumb screw 55 rotatably mounted on a pin 48 secured to the cam lever 30 in a position radial to the fulcrum shaft 42. Rotation of the thumb screw 4%. imparts the desired adjusting movement to the pivot 33', the position of the thumb screw being retained by a spring-pressed ball 50 disposed within a passage in the link 44' to bear on the thumb screw.

As a further means of convenient adjustment of the thread finger stroke, the pivot 38 has at its left end a spherical head 52 (Fig. 4) engaged by a socket in the link 28. The head 52 is arranged eccentrically to that portion of the pivot which passes through the slot 40. Rotation of the pivot 38, therefore, causes the relative positions of the link 28 and lever 30 to be changed and the pivot thereafter is clamped in adjusted position by a check nut 5 on a threaded end of the pivot opposite the ball which engages the C-shaped link 44.

The nature and scope of the invention having been indicated and a particular embodiment having been described, what is claimed is:

l. A shoe inseam sewing machine having a main sewing shaft and stitch forming devices actuated thereby including a curved hook needle, a looper, a thread finger, a take-up and a thread tensioning device, in combination with mechanism for actuating the thread finger to give up thread to the needle and a frictional joint in said mechanism to enable the thread finger to yield according to the requirements of each stitch.

2. A shoe inseam sewing machine having a main sewing shaft and stitch forming devices actuated thereby including a curved hook needle, a looper, a thread finger, a take-up and a thread tensioning device, in combination with mechanism for actuating the thread finger along the line of work feed to draw thread for one side of each needle loop comprising a lost motion connection, and a frictional joint acting on the lost motion connection to enable the thread finger to give up thread to the needle without loss of control according to the requirements of each stitch.

3. A shoe inseam sewing machine having a main sewing shaft and stitch forming devices actuated thereby including a curved hook needle, a looper, a thread finger, a take-up and a thread tensioning device, in combination with mechanism for actuating the thread finger along the line of work feed to draw thread for one side of each needle loop comprising an arm actuated by the sewing shaft, a thread finger actuating shaft on which the arm is mounted, a thread finger carrier in which the thread finger shaft is rotatable, a clamp on the thread finger shaft, and a frictional joint between the clamp and the thread finger carrier.

4. A shoe inseam sewing machine having a main sewing shaft and stitch forming devices actuated thereby including a curved. hook needle, a looper, a thread finger, a take-up and a thread tensioning device, in combination with mechanism for actuating the thread finger along the line of work feed to draw thread for one side of each needle loop comprising a lost motion connection, yielding means to enable the thread finger to give up thread to the needle without loss of control according to the requirements of each stitch, and adjustable means for changing the thread drawing stroke of the thread finger.

5. A shoe inseam sewing machine having a main sewing shaft and stitch forming devices actuated thereby including a curved hook needle, a looper, a thread finger, a take-up and a thread tensioning device, in combination with mechanism for actuating the thread finger along the line of work feed to draw thread for one side of each needle loop comprising a lost motion connection, yielding means to enable the thread finger to give up thread to the needle without loss of control according to the requirements of each stitch, and mechanism for actuating the take-up to draw thread past the thread tensioning device in a plurality of small increments throughout each sewing cycle but to provide slack thread for that portion of a sewing cycle in which the threaded needle is being retracted from the work.

6. A shoe inseam sewing machine having chain stitch forming devices including a curved hook needle, a looper, a thread finger mounted in the machine for movement along the line of feed to measure thread between the looper and the needle, and a channel guide, in combination with mechanism for actuating the thread finger to move it directly behind the channel guide at the end of the thread measuring stroke of the thread finger, said channel guide being bowed to clear the thread finger.

FRED C. EASTMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 935,726 Alley Oct, 5, 1909 1,923,562 Winkley Aug. 22, 1933

Images