US2888892A - Sewing machines - Google Patents

Description

June 1959 T. A. KESTELL ET AL 2,888,892

SEWING MACHINES F iled Oct. 12, 1956 3 Sheets-Sheet l Inven tors Thomas A.Kesfel[ Raymond Snap Filed Opt. 12, 1956 June 9 v T. AfREsTELL EVTAL 2,388,892

SEWING MACHINES v 3 Sheets-Sheet 2 3a I c. 26 w Z [0 Inventors 24 Thomas A. KeszelZ.

June 2, 1959 T. A. KEST ELL ET AL SEWING MACHINES 3 Sheets-Sheet 5 Filed Oct. 12, 1956 fnven tors Thomas fl. Kesfell Paymona Snape United States Patent SEWING MACHINES Thomas Aubrey Kestell and Raymond Shape, Leicester,

England, assignors to United Shoe Machinery Corporation, Boston, Mass., a corporation of New Jersey Application October 12 1956, Serial No. 615,666

Claims priority, application Great Britain November 10, 1955 Claims. (Cl. 112-38) The present invention relates to lockstitch shoe-sewing machines, and more particularly to improvements in a shoe outsole stitcher of the type disclosed in United States Letters Patent No. 2,056,670, granted October6, 1936, on application of J. 'Gouldbourn et al.

In the machine of the Gouldbourn et al. patent a lockstitch seam is formed by employing a locking thread supply containing case mounted within a needle thread loop taker, which carries each loop of needle thread about the thread case, after which the needle loop is contracted against the locking thread and the interlocked needle and locking threads are drawn into the work by a take-up. Heretofore, it has been a problem to control uniformly the action of each needle loop in drawing the locking thread toward and into engagement with the work, the locking thread being subjected to non-uniform action, including varying frictional tension as it is drawn from its supply in the thread case toward the work.

Another cause for lack of uniform action of the locking thread in being drawn by the needle loop into the work arises from an inability to cause initial contraction of the needle loop against the locking thread with certainty at the same relative point along the length of the locking thread running between the thread case and the work. Due to uncertainty in the point at which the needle loop is initially contracted against the locking thread, more or less locking thread may be drawn into the work as each stitch is set, in spite of the provision of extremely eflicient needle thread measuring mechanisms. The problem is complicated further as a result of ineffective tension control on the locking thread, both in the action of frictional tension devices on the locking thread as it leaves the thread case and also from varying effects of inertia in the locking thread supply, such as is met in rotating a supply reel with varying amounts of thread thereon. Consequently, irregular delivery of locking thread frequently occurs as each needle loop contracts against it, rotating the locking thread supply intermittently at relatively high speed, a characteristic difiiculty encountered in most machines of the type referred to.

It is an object of the present invention to improve the uniformity with which a lockstitch shoe outsole stitcher, of the type referred to, forms and sets each stitch of a seam and avoids the difficulties met usually in this type of sewing machine during attempts to control the locking thread, in spite of any uncertainty in point of engagement of the needle loop with the locking thread as the loop is contracted against it.

Other objects of the invention are to simplify and improve the construction and mode of operation of a shoe outsole stitching machine of the type referred to, and to enable the use of a compact and efficient design of thread controlling device mounted on the locking thread supply containing case.

In prior attempts to attain objects of a nature similar to those above enumerated, a yieldable thread control arm-has been provided on a locking thread supply case,

ice

. 2 arranged to take up the looseness in the locking thread, but on account of the restricted space available the amount of thread capable of being payed out by said yielding arm is extremely limited. The yielding force of the am also may vary substantially from one stitch to another on account of unavoidable changes in thread. requirements between successive stitches. Thus, the use: of a yielding arm alone under such conditions does not: necessarily insure uniformity of stitching.

One feature of the present invention enabling improved. uniformity with which a lockstitch sewing machine is: capable of forming and setting stitches comprises theprovision in such machine of stitch-forming devices of conventional form, including a hook needle, a loop taker for passing loops of needle thread about a thread case, a take-up for drawing each loop of needle thread fromthe thread case, and a yieldable control member on thethread case, in which machine there also is provided means for actuating the yieldable member positively in a direction opposite to that of its yielding movement to return it uniformly to a predetermined initial starting position. In this way full benefit is obtained within the restricted space available for the full movement of theyieldable member from its starting position to the end of its thread paying out stroke during each stitch forming cycle. Presumably, the full paying out stroke of the yieldable member is suflicient to accommodate the maximum thread requirements for the machine. Preferably, the actuating means for the yieldable member is in the form of a cam on the loop taker itself, there being no additional mechanism interposed between the loop taker and the work, such as might offer inconvenience, either in manipulation of the work or in applying or removing the supply of locking thread from the machine. As hereinafter described, this feature of the invention is particularly beneficial when employed in a machine having needle thread measuring mechanism, to provide a uniform tension on the locking thread regardless of the irregularities in thread requirements, the full benefit of the needle thread measuring mechanism being thus obtained.

Where no separate mechanism for measuring needle thread is employed, the features of the present invention provide means not only for imparting a uniform tension to the locking thread from one stitch to another, but also for utilizing with success a uniform measurement of locking thread in an amount sufiicient for the formation of each stitch, the full paying out stroke of the yieldable member providing an amount equal to the maximum ordinarily required for each stitch.

The action of the yieldable member, in accordance with a further feature of the invention, is rendered extremely accurate in measuring thread through the provision of lockingthread tensioning and clamping devices, including a conventional thread tension spring and a face on the cam for actuating the yieldable member to prevent withdrawal of locking thread from the supply bobbin during the short interval while each stitch is being set.

These and other features of the invention, hereinafter described and claimed, will be apparent from the follow-' ing detailed specification, taken in connection with the accompanying drawings, in which:

Fig. 1 is a view in right hand side elevation showing a" front portion of the head of an outsole stitcher, embody},

Fig. 3 is a developed view of the cylindrical side wall of the locking thread case shown in Fig. 2, illustrating the relationship of certain of the parts prior to a stitch setting- .operation in the machine;

Fig. 4 is a similar developed view showing the relationship of the same parts while a stitch is being set;

Fig. 5 is a sectional view, looking from the front, on a somewhat reduced scale of the thread supply case shown in 'Fig. 2, including a loop taker surrounding the thread case;

Fig. 6 is a perspective view of a cam on the looptaker for actuating a yieldable thread control-ling member on the thread case;

Fig. 7 is a developed view similar to that illustrated inv Fig. 3 but showing a modified form of the invention; and

Fig. 8 is an enlarged perspective view of a thread tensioning and clamping member shown in Fig. 7.

Except as hereinafter described, the machine illustrated in the drawings is the same in construction, arrangement of parts and mode ofoperation as the machine disclosed in United States Letters Patent No. 2,049,369, granted July 28, 1936, upon application of J. Gouldbourn et al. and No. 2,056,670 above identified. As in the machine of the patents, the stitch-forming devices comprise a curved hook needle 2, a curved awl 4, a needle looper 5, a hollow rotary shuttle or loop taker 6' for passing each loop of needle thread 7 about a locking thread supply case 8 having a cylindrical side wall 9 and an end wall'10, a main take-up 11, a needle thread measuring mechanism, including a swinging thread guiding lever 12, and a pair of needle thread locks 14 and 16. To feed the work presented to the stitch-forming devices, there is provided a feeding work support 18 and a work clamping presser foot 20, both mounted on a horizontally swing-i ing carrier 21. The take-up acts to draw each needle loop from the thread case toward the work, to' contract the loop of needle thread against the locking thread and to pull the interlocked needle and locking threads into the work with a stitch setting tension.

Within the thread case is mounted a bobbin 22 (see Fig. 5 on which a supply of locking thread 24- is wound, the locking thread being led through an opening 26 (Fig. 3) in the cylindrical side wall of the thread case beneath a flat spring frictional tension device 28, acting to con trol withdrawal of locking thread. To hold the tension device in place it is formed with a locking projection 29, fitting a keyhole recess in the thread case 8. From: the tension spring the thread passes through a guide eye 30 in a portion of the cylindrical wall of the thread case near its forward end, which" is left open for convenient insertion and removal of supply bobbins. To prevent rotation of the thread case with the loop taker 6, thethread case along its front end is provided with a pair of forwardly extending lugs 32, between which is loosely engaged a removable thread case retainer in the form of an arm 34, the locking thread 24 issuing from the guide eye 30 and extending toward the work close to one side of the retainer arm 34.

As in the operation of the machine of the prior patents, a measured amount of needle thread is provided for each stitch by the thread measuring lever 12 and the take-up acts to withdraw the needle thread through the lock 14, which is opened at the proper time, so that the measured amount of needle thread is rendered available for the the work is held straight under rigid tension before initial engagement with the needle loop, the needle loop will slide along the locking. thread while in straight condition toward a position at its point of emergence fromthe previous stitch in the work. Thereaften-duringi con- 4 I tinned contraction of the needle loop the locking thread is deflected from straight tensioned condition and is drawn from the thread case, the needle loop sliding along the deflected portion of the locking thread in a reverse direction away from the previous stitch until the deflected locking thread is pressed against the surface of the work by the contraction of the needle loop against it. Continued tension of the needle thread then causes additional locking thread to be drawn from the thread case into the work and the stitch to be set. However, if the locking thread running between the guide eye 30 and the work is untensioned and slack before the needle loop is contracted against it, the length of locking thread between the previously formed stitch and the needle loop is greater before additional locking thread is drawn from the thread case than otherwise would be. The initial point of interlocking engagement between the threads will then be further away from the point of emergence of the locking thread from the previous stitch and as a result less tension in the needle thread will be required to deflectthe locking thread against the work. Accordingly, more locking thread will be drawn from the thread case and the final point of interlocking engagement of the threads will be drawn more deeply into the work when the stitch is set, than would occur when the locking thread is held straight under rigid tension between the guide eye 30 and the work, in a manner to direct the contracting needle loop immediately to the point of emergence of the locking thread from the work. For these reasons irregularities in formation and setting of successive stitches have resulted. As thus far described the machine is substantially the same as disclosed in the prior patent, above referred to.

As in prior attempts to maintain the locking thread" under rigid tension between the locking thread supply case and the work, the present machine is provided with a yieldable paying-off device for taking up the slack locking thread running between the tension member 28 on the thread case and the work. However, the space avai'h" able for the paying-0E device is so small that its movement is extremely limited and unless the full movement of the device is available for paying-off locking thread and for maintaining it under yielding tension during the successive stitches still are frequent.

According to an important feature of the present invention, the full length of movement of the yieldable paying-oif device is obtained by providing an actuatingmeans' therefor, operable positively in a direction opposite to that of the yielding movement of the yieldable device to return it unifonnly to an initial predetermined starting position during each sewing cycle. As illustrated in Fig. 2, the yieldable paying-off device comprises an enlarged head 36, having a thread guiding eye, on a substantially inentialess spring member 38 formed of steel wire; The spring member 38 is wrapped about the thread case cylindrical side wall through an extent of about of its periphery and is anchored at one end 40 in a flange of the thread case. The head 36 is situated in a transverse cutout section 41 of the cylindrical side wall of the thread case and is thus able to move to a limited extent through machine is capable of successful operation. The locking thread in the bight is thereafter available for movement yieldingly toward the work as a stitch being. formed is set.

Prior tothe' stitch setting action, the spring member38 occupies a predetermined initial'position represented in Fig. 3. ln this-position it will be observed that the spring fiiember 38 is located with its head at the rearward limit of its movement near to the rear of the thread case 8, as viewed by an operator of the illustrative machine. Furthermore, in this same position (Fig. 3) the yieldable paying-E device provides a bight in the thread and the spring tension member 28 presses the locking thread 24 firmly against the periphery of the thread case 8 to maintainthe locking thread in a straight position between the paying-off device and the work. The thread tension due to the spring 28 may, in a typical example, be of the order or 1% pounds.

As will be seen from Fig. 5, the thread case 8 is situated within an annular interior of the loop taker 6, the latter being arranged to rotate about the thread case 8 and having a beak 42 for entering and carrying each loop of needle thread 7 over the loop taker and over the locking thread supply bobbin. The loop of needle thread is drawn down from the shuttle to the work and is contracted about the locking thread 24 to bring about the setting of each stitch at the point of final interlocking engagement between the needle and locking threads within the work.

During the stitch setting operation, i.e., as the needle loop exerts tension against the locking thread 24 and deflects it toward the work, the paying-off spring 38 yields under the pull of the needle thread away from its initial starting position, represented in Fig. 3 and towards that which is represented in Fig. 4. The spring member 38 is then located with its head near the front of the thread case 8. In a typical example the spring member 38 may be such as to impart an average tension which is of the order of 12 ounces, it being appreciated that as the needle thread exerts tension on the locking thread 24 during the stitch setting operation, the spring member 38 yields lightly and pays out as much locking thread as is necessary for the correct setting of the stitch without any withdrawal from the supply bobbin 22.

After the stitch has been set the spring member 38, according to the invention, is returned positively into its initial predetermined starting position, represented in Fig. 3, during which time the head 36 of the spring member 38 acts to draw off from the bobbin 22 an amount of locking thread suflicient to provide a predetermined length for the next succeeding stitch. In a typical example, this amount of draw-off from the supply bobbin 22 may vary from about 35 of an inch for minimum conditions to about of an inch for maximum conditions.

Referring now to Figs. 5 and 6, the positive return movement of the spring member 38 to its initial position is effected by means of a circular scroll cam 44 in the form of a sleeve which is pressed tightly into the annular interior of the loop taker 6 to rotate therewith around the locking thread case 8. The cam 44 at one end is formed with a helical edge face 45 against which the head 36 of the spring member 38 bears and by which face it is thrust progressively from the limit position represented in Fig. 4, to that which is represented in Fig. 3. When the spring member 38 has thus been returned positively by the cam 44 into the position represented in Fig. 3 before each stitch is set by the take-up, a step 46 formed in the cam frees the head 36 for yielding movement during contraction of the needle loop in the setting of the next stitch. It will be understood, of course, that the contour of the cam 44 and its angular disposition relatively to the loop taker and to the head 36 will be chosen suitably to ensure that repetitive thread draw-off movements, alternating with thread pay-off movements, of the spring member 38 occur in the desired times as the loop taker 6 rotates.

To accentuate the locking thread draw and pay-off movements of the yieldable member 38 and to prevent withdrawal of locking thread from the supply bobbin 22 at other than the proper time, the cam 44 of the illustrated machine is formed on its inner peripheral surface with an enlargement 48 (Figs. 5 and 6) extending through an angle somewhat greater than as indicated at points a and b in Fig. 5. As the loop taker rotates the enlargement 48 presses against a projection 50 on the tension spring 28 and applies a supplemental clamping pressure to the thread running from the supply in the locking thread case. To apply a supplemental clamping pressure to the thread tension spring at the proper time the relative position of the enlargement 48 and the projection 50 are such that the supplemental pressure for the thread tension spring occurs while each stitch is being set by the take-up thus causing the locking thread to be clamped by the tension spring against the outer surface of the thread case.

In Fig. 7 is illustrated a modified arrangement of a yieldable paying-off device. Instead of employing a thread tension spring 28 engaging the locking thread 24 between the bobbin and the spring member 38, as is shown in Fig. 3, a thread-tension spring 52 which encircles the thread case 8 and is retained in position by means of a locking projection 54 (Fig. 8) fitting within a keyhole recess formed in a side Wall of the bobbin case 8, has its free end arranged to bear upon the locking thread 24 as it runs along the periphery of the thread case between the eye 30 and the head 36 of the spring member. The locking thread 24, as it extends from the bobbin passes freely under the spring 52 as it emerges from the opening 26, the thread-tension being applied by reason of the free end only of the spring 52 pressing upon the locking thread near to the eye 30 between the yieldable member 38 and the work. In this arrangement, when the setting operation of the stitch occurs, the stitch is set against a combination of two tensions, namely, one tension due to the spring 52 and the other due to the spring member 38. It is to be understood that the movements of the spring member 38 to effect pay-off and drawoff of the locking thread 24 takes place in a manner similar to that which has been described above in connection with the arrangement shown in Figs. 2 to 6, inclusive. The scroll cam 44, however, need not be provided with an enlargement 48, since in the modified arrangement shown in Fig. 7 sufiiciently satisfactory results may be obtained without applying any additional clamping pressure to the spring 52 at the stitch setting point of the sewing cycle. Where extremely accurate stitch formation is required, however, the enlargement 48 is helpful in improving uniformity between the placement of the interlocking threads of successive stitches. Similarly, even in connection with the arrangement shown in Figs. 2 to 6, the enlargement 48 may be dispensed with in cases where sufficiently satisfactory results are found to be obtainable without applying the additional clamping pressure to the tension spring.

While the merit of the illustrated forms of the present invention is derived in a large degree from the eflicient utilization of limited space available in the cylindrical side wall of a locking thread case by insuring a maximum possible movement of a yieldable thread paying-off device, the uniformity with which the device acts to pay off thread also is a contributing factor. Because the thread guiding head 36 of the yielding member 38 also moves from the same initial starting position in paying-oflf thread, the same yielding resistance is imparted to the thread as each stitch is set in the work with the same tension on the locking thread. If the head 36 of the yieldable member moved from a position other than the initial one, the yielding force exerted by the member 38 would be increased correspondingly on account of the spring characteristics even though all of the thread drawn off by the yieldable member were not taken up before the head 36 engages its positive stop at the outer edge of the cutout section 41. In this way the locking thread extending between the thread case and the work not only is maintained in straight position under tension as each needle loop is being drawn toward the work and contracted against the locking thread, but the actual amount of tension in the locking thread is kept from variation from one stitch to another so long as the thickness of the work and the 7 length of stitch does not change. With changes in thickness of the work and length of stitch corresponding varia tions may occur in the tension on the locking thread but in a manner which is beneficial to the formation of a seam, the tension in the threads of which are commensurate with the requirements.

The nature and scope of the invention having been indicated and specific embodiments having been described, what is claimed is:

1. A lockstitch sewing machine having stitch-forming devices, including a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a takeup for drawing each needle loopfrom the thread case toward the Work, means for controlling withdrawal of thread from the thread case, and a yieldable member on the thread case for taking up slack thread between the thread case and the work, in combination with means for actuating the yieldable member positively in a directionopposite to that of its yielding movement to return it uniformly to an initial predetermined starting position.

2. A lockstitch sewing machine having stitch-forming devices, including a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work, means for controlling withdrawal of thread from the thread case, and a yieldable member on the thread case for taking up slack thread between the thread case and the work, in combination with means comprising a cam on the loop taker for actuating the yieldable member positively in a direction opposite to that of its yielding movement to return it uniformly to an initial predeterminedstarting position and to draw off from the supply of locking thread an amount suilicient for the next succeeding stitch. V

3. A lockstitch sewing machine having stitch-forming devices including a hook needle, a thread case having a cylindrical side wall containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work and a yieldable paying-oft device mounted on the cylindrical side wall of the thread case for limited yielding movement to take up slack thread between the thread case and the work, in combination with means operable positively in a direction opposite to that of the yielding movement of the yieldable device to return said device uniformly to an initial predetermined starting position.

4. A lockstitch sewing machine having stitch-forming devices including a hook needle, a thread case having a cylindrical side wall containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work and a yieldable paying-elf device mounted on the cylindrical side wall of the thread case for limited yielding movement to take up slack thread between the thread case and the work, in combination with means operable positively in a direction opposite to that of the yielding movement of the yieldable device to return said device uniformly to an initial predetermined starting position, comprising a circular scroll cam within the loop taker, the helical edge face of which bears against the yieldable paying-oil device.

5. A lockstitch sewing machine having stitch-forming 8 member positively in a direction opposite to that of its yielding movementto return it uniformly to an initial predetermined starting position and to draw off from the supply of locking thread an amount sufiicient for the next succeeding stitch, and means for preventing rotation of the thread case with the loop taker. I g

6. A lockstitch sewing machine having stitch-forming devices, including a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work, means for controlling withdrawal of thread from the thread case, and a yieldable member onthe thread case for taking up slack thread between the thread case and the work, in combination with means comprising a cam on the loop taker for actuating the yieldable mermber positively in a direction opposite to that of its yielding movement to return it uniformly to an initial predetermined starting position and to draw off from the sup ply of locking thread an amount sufiicient for the next succeeding stitch, and means comprising an enlargement on the cam engaging the thread controlling means to prevent withdrawal of locking thread from the supply in the thread case while each stitch is being set by the take-up.

"l. A lockstitch sewing machine having stitch-forming devices,- including a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work, means for controlling withdrawal of thread from the thread case, and a yieldable member on the thread case for taking up slack thread between the thread case and the work, in combination with means comprising a circular scroll cam formed with a helical edge face for actuating the yieldable member and to enable thread to be paid off as each stitch is set by the take-up, and means comprising an enlargement on the inner surface of the cam acting on the thread controlling means to prevent withdrawal of locking thread from the supply in the' thread case while each stitch is being set by the take-up;

8. A lockstitch sewing machine having stitch-forming devices, including a hook needle, a thread case containing a supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work, means for controlling withdrawal of thread from the thread case, and a yieldable member on the thread case for taking up slack thread between the threadcase and the work, in combination with means comprising a circular scroll cam formed with a helical edge face for actuating the yieldable member and to enable thread to be payed off as each stitch is set by the take-up, and means comprising an enlargement on the inner surface of the"- canr acting on the thread controlling means to prevent withdrawal of locking thread from the supply in the thread case while each stitch is being set by the take-up,- the thread controlling means comprising a flat tension spring engaging the thread between the yieldable slack thread take-up member and the work.

9. A lockstitch sewing machine having stitch forniing devices, including a hook needle, a thread case containing a' supply of locking thread, a loop taker for passing a loop of needle thread about the thread case, a take-up for drawing each needle loop from the thread case toward the work, means for controlling withdrawal of th'rea'd from the thread case, and a yieldable member on the thread case for taking up slack thread between the thread case and the work, in combination with means com rising a circular scroll cam formed with a helical edge face for actuating the yieldable member and to enable thread to be payed off as each stitch is set by the take-up, and means comprising an enlargement on the inner surface of the cam acting on the thread controlling means to preventwithdrawal of locking thread from the supply in the thread case While each stitch is being set by the take-up,

the thread controlling means comprising a thread tension spring arranged to bear on the locking thread between the yieldable slack thread take-up member and the work.

10. A lockstitch sewing machine having stitch-forming devices including a hook needle, a thread case having a cylindrical side wall and containing a supply of locking thread, a loop taker for passing a loop of needle thread about said thread case, a take-up for taking up each needle loop from the thread case and drawing it toward the work, a needle thread measuring mechanism providing a measured amount of needle thread for each stitch, means for controlling withdrawal of locking thread from the thread case, and a yieldable member on the thread case for taking up slack thread between the supply in the thread case and the work, in combination with means for actuating the yieldable member positively in a direction opposite to that of its yieldable movement to cause the yieldable member to draw thread from the thread case in an amount equal to that drawn into the work by the needle thread while the previous stitch is being set.

Ballard June 8, 1915 Haas Feb. 21, 1939

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