US3177832A - Magnetic thread cases and oscillating looptakers - Google Patents

Description

April 13, 1965 G. F. c. BURKE ETAL MAGNETIC THREAD CASES AND OSCILLATING LOOP'IAKERS Filed Nov. 13, 1962 5 SheetsSheet l Inventors: Gearye F CBur/te J/ton C'op/thorne .53 (he/r flUo/"ney WM) April 1955 ca. F. c. BURKE ETAL 3,177,832

MAGNETIC- THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5 Sheets-Sheet 2 April 13, 1965 G. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 15, 1962 5 Sheets-Sheet 3 April 13, 1965 G. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5 Sheets-Sheet 4 April 1965 s. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5 Sheets-Sheet 5 United States Patent 3,177,832 IVIAGNETIC AD CASES ANDVGSCHLATHJG LUGPTAKERS 7 George F. Q. Burke, Beverly, and Alton R. Copithorne, Rowley, Mass, assignors to United Shoe Machinery Corporation, Boston, Mass, a corporation of New Jerse y Filed Nov. 13, 1962, Ser. No. 237,258

8 (Jlairns. (Cl. 112-33) This invention relates generally to improvements in look stitch shoe outsole sewing machines or stitchers and more particularly to a looptaker and cooperating thread case construction especially useful in such machines.

Conventional stitchers of most modern types generally include rotary looptakers for interlocking the needle thread with a locking thread by passing a loop of needle thread about a stationarythread case in which is maintained a supply of locking thread. Such a looptaker is driven continuously two or three revolutions during each sewing cycle and during one revolution of each cycle carries the needle loop.

Major disadvantages of conventional looptaker arrangements include a complex shape which in order to be eltective must be formed with a high degree of accuracy and accordingly results in a high manufacturing cost. In addition, the high speed of rotation tends to minimize the useful life of looptakers which, being expensive to manufacture and to replace, results in a machine which is expensive to maintain. The thread cases associated with such looptakers are also complex in form and subject to rapid wear thereby adding to the cost of maintenance.

Equally important is the fact that the common ratio of three revolutions of the looptaker during each sewing cycle is an important limiting factor upon attainable sewing speeds. Another disadvantage of conventional thread case constructions is that in replenishing the locking thread supply a hot bobbin must be replacedand handled by the operator thereby increasing the time required for locking .thread supply replenishment and consequently resultingin lowered efficiency of machine utilization.

It is accordingly an object of the present invention to reduce the manufacturing cost ,of looptakers suitable for lock stitch shoe sewing machines.

Aniadditional object is to provide readily manufactured, easily replaceable parts most subjectto wear in looptakers so that the cost of machine maintenance may be effectively reduced. .7 Y

Still another object is to provide a looptaker construction in which portions of the machine instrumentalities coming into contact with thethread do not-require lubrication and hence maybe. operated dry without danger pf soiling work pieces and without shortening their useful ife.

Still another object is to provide a looptakerconstructionof minimum mass suitable for oscillatory movement at high sewing speeds.

tant feature of the invention resides in a looptaker having a plow-shaped beak which engages a spread-open needle loop and carries it part way. about a thread case as thread is supplied by a thread hook and takeup of generally conventional design. Mounted within the path of the hook are a pair of annular thread guiding members or rings one of which is fixed and the other hinged so that it may be opened to receive the thread case which is mounted between the'rings. The thread case is somewhat loosely mounted between the guide rings and thus adapted. to be moved slightly by the needle loop in passing about the case. The guide rings are of magnetic material and formed with conical interior surfaces which are notched to receive a loosely fitted stem of the thread case thereby to prevent angular displace ment of the case by the passage of the thread. The thread case, according to another feature of the invention, is of light nonmagnetic material and provided with a series of inserted magnets so that the attraction of the magnets to the rings positions the case to facilitate the passage of the needle loop.

Other features of the invention including the form of the plow-shaped hook for economy of manufacture and ease of replacement and the provision of a heat source to facilitate the use of certain types of coated threads will be readily appreciated from the following detailed description of an illustrative embodiment of the invention taken in connection with the accompanying drawings, in which FIG. 1 is a fragmentary view in perspective as seen from the front and right and partly in exploded relationship of a looptaker and thread case according to the present invention;

FIG. 2 is a view in front elevation of some of the parts shown in FIG. 1, particularly depicting the looptaker at the completion of a needle loop carrying motion;

FIG. 3 is a view in cross section taken along the line III-III of FIG. 2, showing the mountingof the locking thread case within a pair of annular thread guiding members; FIG. 4 is a view partially in cross section taken along the line IV-IV of FIG. 2 and depicting the position of a needle thread loop on the looptaker;

FIG. 5 is a greatly enlarged view showing the interior construction of a stem forming part of the thread case;

FIG. 6 is a view in cross section depiciting the stem of FIG. 5, its .interior construction and its relationship Yet another object is to provide a removable thread case 'structureadapted to being economically produced so that the replenishment of the locking. thread supply may be accomplished quickly by replacing the empty thread case with onecontaining a new supply. of thread.

A still further object is to provide thread guiding case and includinginexpensive means for retaining the thread case in position for needle loopsto be passe 'aboutit. H

In the achievementof theforegoing objects an importo the thread case and to the annular thread guides;

FIG. 7 is a view of the parts depicted in FIG. 6 as seenrfrom the point of exit of the locking threadfrom the locking thread case; i

FIG. 8 is a fragmentary schematic view of a sewing machine showing a takeup and other thread handling instrumentalities in addition to the looptaker construction, according to the present invention;

FIG. 9 is a schematic view in perspective in which portions of thread guiding members are broken. away to show the thread case and in which the beak of the loop taker carrying a needle loop is depicted in successive angular positions;

FIGS. 10 and 11 are fragmentary views of the beak of the looptaker'showing successive stages in the disengagement of the needle loop from the beak of the looptaker.

The present invention is embodied in a heavily con- 7 structed lock stitch shoe sewing machine including a members associated with the looptaker and the thread awl 14 the workpiece, which may be'thought of as coma prising the outsole 16 and the' welt 18 of a shoe, rests upon a work support 29 and is clamped by a presser foot 22. Otherconventional instrumentalities of the machine for manipulating a needle thread 24 include a looper 26, a thread storing hook 28, a takeup 30,,and' front and rear thread locks indicated at 52 and 34 respectively. Acting between the thread locks is a thread measuring arrangement of usual design including a thread measuring finger 36.. g V

. According to the present invention, the needle thread 24 is interlocked with a lockin thread 38 by a looptaker 49 of simple, novel and economical construction. The looptaker 4t) is oscillated about the axis. of a shaft 42 and includes a plow-shaped beak 44 which travels over an arcuate path about a fixed inner guide ring 46 and an outer guide ring 48. A thread case indicated generally at 50 is supported loosely between the guide rings 46, 48 and encloses a quantity'of locking thread or cop 51 preferably in the form of the thread package, disclosed in an application for United States Letters Patent Serial No. 156,316, filed December 1, 1961, in the names of George F. C. Burke and Robert W. Bradley and now abandoned.

Connections for imparting an oscillatory movement to the looptaker 49 are driven from a sewing shaft 52 which is journaled in the frame and driven one revolution for each stitch in conventional manner. Miter gears 54 and 56 keyed respectively to the sewing shaft 52 and to a cam shaft 53 are included among the driving connections for the looptaker 40V The shaft 58 which is journaled in the frame 10 has keyed to it a pair of conjugate cams 60 and 62 the contours of which are engaged respectively by follower rolls 64 and 66 rotatably supported on two arms of a'lever 68. The lever 68 is pivoted on a headed shaft 70 pinned in the frame 10 and is formed with a generally vertical arm the lower end of which terminates in a gear sector 72 engaging the teeth of a pinion 74 formed integral with the shaft 42. The front end surface of the pinion 74 is slotted to receive an integral key 76 on the looptaker 4% which is also pierced for a retaining screw '78 passing loosely through the looptaker and into engagement with the threads of a tapped hole in the shaft 42. a

The thread case 56 is formed of nonmagnetic material with conical thread engagingsurfaces intersecting and defining a ridge 82 which serves'to separate the legs of each loop of needle thread as it is passed over the case. The case 50 isof a material which offers the advantages of low weight, high abrasion resistance and dimensional stability. These qualities are available in a variety of well-known synthetic polymeric materials which may be inexpensively molded to finished dimensions. Enclosed within the body of the thread case 50 preferably as molded inserts are two sets of permanent magnets 84, 86, all preferably polarized in the same direction, which assist in positioning the case-between the guides 46 and 48. The thread is brought out from the inside of the case through a hollow stem 88 containing a leaf spring friction 90 secured to the stem by screws 91. The stem itself is preferably molded into the body of the case. The rings 46 and 48 are notched at 92 loosely to embrace the stem 88 and thus prevent the case from being angularly displaced by the passage of the thread but leaving sufiicient space to permit the needle thread to pass. between the stem and the Walls of the notches. The case itself is received between the rings 46, 48 which are of magnetic material, by opening the ring 48 which for this purpose 192 for passage of the locking thread and also with an opening 104 (FIGS. 3 and 9) for observing the remaining supply of locking thread and to permit the introduction of heated air to soften the coating normally applied to the thread. To prevent Withdrawal of the shield from the interior of the case a thin retaining plate 195 is secured to the guide ring 48.

Heated air is introduced into the inside of the cop 51 through the opening 104'by means of a nozzle 106 (FIG. 8) in communication with a conduit 107 secured by a clamp 198 to the frame of the machine. Inside the conduit 1&7 is a thermostatically-controlled, electricallyheated cartridge 112 and the conduit is connected through a'fiexible pipe 114 to a source of air under pressure. Both the quantity of air and the temperature setting of the thermostat may be regulated to suit the particular type of coating applied to the thread. The heated air thus introduced permits even thread coated with highly adhesive waxes to be smoothly Withdrawn from the cop.

The operation of the present looptaker arrangement will best be understood from a description of the passage of a single loop of thread about the thread case 50. At the time that the needle 12 withdraws carrying the loop of needle thread the beak 44 is in the solid line position of FIG. 9 below the needle loop as it is opened by a loop spreader 116.

The movement of the thread over the thread case 50, star-ting with the pick up of the needle loop by the beak 44 and ending with its release from the beak will best be understood from a description of the disposition of the needle thread in successive positions of the beak, as seen in FIG. 9, and identified by letters A, B, C, D and E. In the present machine the needle loop is passed over the thread case without being twisted so that the standing leg of the loop, rearward side of the thread case while the running leg, designated by the symbol R, passes over the front of the case, the standing leg being thatpart of the thread running between the beak and the stitch hole from the last stitch and :the running leg being the part of the thread running between the beak and the stitch hole and on to the thread is hinged at 94,- and is secured in operative position by a X-Shaped clamp 96 provided with a knurled clamp screw 98, about which it may be moved between inoperative position (FIG. 1) and operative position (FIG. 2).

The cop 51 is received within the case 50 in a cupshaped shield 100 of thin nonmagnetic resilient metal such as phosphor bronze and removably retained inside the thread case. The shield is formed with an aperture supply.

As seen in FIG. 2, the plane of the beak 44 defines a hook angle X with a radial plane passing through the axis of the shaft 42 and the point of intersection of the beak with an upstanding horn 120 which, with a shoulder 122, best seen in FIG. 9, limits entry of the beak into the loop of the needle thread. The hook angle is typically in the order of 60 to assure retention of the needle loop by the beak. An included angle Y defined between the two arms of the beak, as seen in FIG. 8, is preferably equal to between 70 and and the size of this angle also interacts with the magnitude of the hook angle already mentioned as will later be explained.

Returning to FIG. 9 it will be seen that in moving between positions A and B a horizontal portion of the needle loop extending between the needle 12 and the loop spreader 116 is picked up by the beak and because of the direction of the hook angle X is pulled inwardly toward the axis of movement of the beak. In traveling between the positions B and C the looptaker causes the partial unwrapping of the needle thread from the barb of the needle and durnig this time the loop spreader 116 is moved rearwardly to relinquish-complete control over the needle loop to the beak 44. The motion of the beak from positions B to C causes the needle loop to expand in size and for this purpose a part of the thread required by the standing leg is supplied .by the thread hook 28 while the remainder of the thread is yielded by the takeup 30. At the position D of the beak the needle loop is completely free of both the needle 12 and of the loop spreader 116 and an intermediate point on both the standing and running legs has engaged inwardly sloping surfaces of the guide rings 46, 48 respectively, so that the legs are directed closer together and into contact with designated by the symbol S, passes across the It will also be observed that the beak 44 is formed with a forwardly extending appendage 124 for controlling the progressive wrap of the thread about the cross section of the beak as the beak moves from the position B to the position E. Shortly after the position D is passed, the needle loop reaches its maximum extension and thereafter no more thread need be yielded by the take-up 30. The legs of the loop having been brought into engagement with the thread case between the guide rings 4-6 and 4-3 are divided by the ridge S2 and begin to flow over the rearward and forward faces of the thread case. As this flow over the front and rear faces of the thread case occurs, the legs of the needle loop first pass between the magnets 34 and the guide rings 46 and 48 causing the case 50 to be depressed slightly from its normal position. As the case is thus depressed its'position is maintained by the attraction between the magnets 86 and the guide rings while the case pivots about the stem 38 in the notches of the guide rings. Thereafter the legs of the needle loop are drawn by. the beak between the magnets 86 and the guide rings as the magnets 84 are ragain'attracted to the guide rings and the thread case rises to its normal position. As the beak reaches the position E, the legs of the needle loop which at position B were wrapped about approximately one quarter of the cross.

section of each arm of the beak, are now wrapped about" approximately three quarters of the cross section. At this point in the operating cycle of the machine the movement of the beak is arrested and the take-up 3t) begin to contract the needle loop thus shortening the running leg R which passes completely across the front face of the thread case. Since the stitch hole is approximately in line with the ridge 82, as seen in FIG. 8, the running leg having completed its passage across the front face of the thread case is then reoriented with respect to the beak 44 from the dash line position to the solid line position, shown in FIG. 10. After the length of the running leg has been shortened to the point that it is disposed in essentially a straight line running from the stitch hole to a point near the horn 120 on the beak, continued retraction of the thread by the take-up 30 causes the point of contact of the running leg Rat the beak to slide downwardly toward the tip of the beak, as shown in FIG. 10. The horizontal portion of the needle loop bridging the eak between the legs of the loop is shortened by further retraction of thread and the points of engagement of the loop on the beak correspondingly slide closer together. As the points of contact reach the inside apex of the loop the legs press against the horizontal portion and the loop is thereby snapped ol'r the point of the beak and thus freed, as seen in FIG. 11. After being freed from the beak the needle loop continues to be retracted and is thus drawn between the thread case and the guide ring 46 until it moves completely out of engagement with the thread case, having been interlocked with the locking thread from the cop 51, as shown in the incomplete stitch depicted in FIG. 2. Thereafter the continued pull of the take-up upon the needle thread causes the interlocked portions of the two threads to be set as a complete stitch in the thickness of the outsole 16.

The inter-relation between the hook angle X and the included angle Y is realized from considering the function of the beak 44 in picking up the loop at the position B with reliability and in releasing the loop in the position E under conditions of permissible thread tension. An increase in the hook angle X beyond the indicated 60 value improves the reliability of loop pickup and retention because of the fact that the tip of the beak is tilted upwardly in the position B. However, in the position E a hook angle of 60 which provides adequate reliability for carrying the loop offers a suitable angle of approach to the running leg R so that disengagement of the loop from the beak may be achieved without excessive thread tension. The position of the beak in its loop releasing position is effected by the necessary relationship of the axis of the thread case with the point of penetrationof the work by the needle which in turn provides clearance for the work piece without excessive extension of the needle loop.

The included angle Y may be reduced below the approximate shown in FIG. 8 and this reduction in the size of the included angle enhances the performance of the beak in' entering theloop and retaining it until the beak reaches the position E. However, a reduction below the 70 to range indicated as acceptable for the included angle greatly increases the tension required to cause slippage of the needle loop oif the beak. On the other hand a substantialincrease above the acceptable range of the included angle causes the loop tobe wedged off the beak under working tension before the position E is reached and accordingly causes the missing of stitches and reduces the reliability of the machine.

Having thus described our invention what we claim as new and desire to secure by Letters Patent of the United States is:

1. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing point and for withdrawing from the work piece carrying a loop of needle thread, a take-up for yielding thread to the needle during its withdrawal from the workpiece and during further expansion of the needle loop, in combination with a pair of notched thread guiding members of magnetic material, a thread case for containing a supply of lock: ing thread, means for magnetically attracting the thread case to the thread guiding members, a hollow stem on the thread case entering the notches of the guiding members and formed with a passage for the locking thread, and' means for carrying the loop of needle thread about the case.

2. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing point and for withdrawing from the work piece carrying a loop of needle thread, a sewing shaft, a take-up for yielding thread to the needle during its withdrawal from the workpiece and during further expansion of the needle loop, in combination with a pair of generally annular thread guiding members of magnetic material, a nonmagnetic thread case, magnetic inserts in the case attracted to the thread guiding members, and means for carrying the loop of needle thread about the case including a plow-shaped beak and connections to the sewing shaft for oscillating the beak over a path around a part of the periphery of the guide members.

3. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing point and for withdrawing from the work piece carrying a needle thread loop having two legs, a sewing shaft, a take-up for yielding thread for enlargement of the needle loop and retracting thread to contract the needle loop, in combination with a pair of generally annular thread guiding members, a thread case retained against rotation and loosely supported between the thread guiding members, a plow-shaped needle loop-carrying beak having interior surfaces upon which both legs of the needle loop slip toward the tip of the beak for disengagement of the loop from the beak when the beak is in a loop-shedding posi tion and the loop is contracted by the take-up and connections to the sewing shaft for oscillating the beak from a loop-entering to the loop-shedding position.

4. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing point and for withdrawing from the work piece carrying a needle thread loop having two legs, a sewing shaft, a take-up for yieldin gthread for enlargement of the needle loop and retracting thread to contract the needle loop, in combination with a pair of generally annular thread guiding members, a thread case retained against rotation, loosely supported between the thread guiding members for containing a supply of locking thread, a'plovwshapedj needle loop carrying beak having an included angle of between 70' and 110* and a pair of interior surfaces upon each of which one of the legs of the needle loop slips toward the tip of the beak for disengagement of the loop from the beak when the beak is in a loop-shedding position and the loop is contracted by the take-up, and connections to the sewing shaft for oscillating the beak from aloop-entering to the loop-shedding position. I

5. A sewing machine having a curvedv hook needle for penetrating a leather Work piece at a sewing point and for withdrawing from the work piece carrying a loop of needle thread,'a sewing shaft, a take-up for yielding thread for enlargement of the needle loop and retracting thread to contract the needle loop, in combination with a pair of generally annular thread guiding members, a thread case retained against rotation and loosely supported be tween the thread guiding members, a plow-shaped needle loop-carrying beak movable about an axis and oriented relative to the axis to present a hook angle of approximately 60 and'having interior surfaces upon which the needle loop slips toward the tip of thebeak for disengagement from the beak when the beak is in a loop-shedding position and the loop is contracted by the take-up, means on the beak for limiting the entry of the beak into the needle loop, and connections to the sewing shaft for oscillating the beak from a loop-entering to the loop-shedding position. g

6. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing point and for Withdrawing from the work piece carrying a loop of needle thread, a sewing shaft, a take-up for yielding thread for enlargement of the needle loop and retracting thread to contract the needle loop, in combination with a pair of generally annular notched magnetic thread guiding members, spaced apart in parallel relation along a common axis and formed with concavecase-supporting surfacestandconvergent thread guiding surfaces, a thread case for containing'a supply of locking thread, loosely supported between the thread guiding members, means for retaining the case against rotation including a hollow stem loosely entering the notches and through which the locking thread passes on its way to the work piece, magnetic inserts in the case attracted to the guiding members and means for carrying the needle loop about the thread case.

7. A sewing machine having a curved hook needle for for enlargement of the needle loop and retracting threadto contract the needle loop, in combination with a pair of generally annular notched magnetic thread guiding members, normally spaced apart in parallel relation along a common axis and formed with concave case-supporting surfaces, a hinge mounting for one of the guidingmembers, a latch retaining the hinged member in parallel relation with the other, a thread case loosely supported between the thread guiding members, means including a hollow stem entering the notches in the guiding members for retaining the case against rotation, magnetic inserts in the case attracted to the guiding members and means for carrying the needle loop about the thread case.

8. A sewing machine having a curved hook needle for penetrating a leather work piece at a sewing pointtand for withdrawing from the work piece carrying a loop of needle thread, a sewing shaft, a take-up for yielding thread for enlargement of the needle loop and retracting 7 thread to contract the needle loop, in combination with a pair of magnetic. thread guiding members, normally spaced apart in parallel relation along a common axis, a thread case loosely supported between the thread guiding members, means for retaining the case against rotation,

two sets of similarly polarized magnetic inserts in the case attracted to the guiding members including a first set holding the case in normal position and a second set. efiective while the needle loop isbeing passed through the area of attraction of the first set, and means for carrying the needle loop about the thread case.

References Cited by the Examiner UNlTED STATES PATENTS 1,063,987 6/13 Mack 112-231 X 2,394,369 2/46 Colegrove 112-228 X 2,420,643 5/47 Ashworth 112-38 2,543,475 2/51 Slodysko 112--229 v72,608,945 9/52 Hagquist 112-181 2,763,227 9/56 Howard 11223l 2,784,690 3/57 Brandt 112-l81 3,074,367 1/63 Habedank et a1. 112--228 JORDAN FRANKLIN, Primary Examiner.

Claims (1)

1. 3. A SEWING MACHINE HAVING A CURVED HOOK NEEDLE FOR PENETRATING A LEATHER WORK PIECE AT A SEWING POINT AND FOR WITHDRAWING FROM THE WORK PIECE CARRYING A NEEDLE THREAD LOOP HAVING TWO LEGS, A SEWING SHAFT, A TAKE-UP FOR YIELDING THREAD FOR ENLARGEMENT OF THE NEEDLE LOOP AND RETRACTING THREAD TO CONTRACT THE NEEDLE LOOP, IN COMBINATION WITH A PAIR OF GENERALLY ANNULAR THREAD GUIDING MEMBERS, A THREAD CASE RETAINED AGAINST ROTATION AND LOOSELY SUPPORTED BETWEEN THE THREAD GUIDING MEMBERS, A PLOW-SHAPED NEEDLE LOOP-CARRYING BEAK HAVING INTERIOR SURFACES UPON WHICH BOTH LEGS OF THE NEEDLE LOOPS LIP TOWARD THE TIP OF THE BEAK FOR DISENGAGEMENT OF THE LOOP FROM THE BEAK WHEN THE BEAK IS IN A LOOP-SHEDDING POSITION AND THE LOOP IS CONTRACTED BY THE TAKE-UP AND CON-

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