US2219933A

US2219933A - Shoe sewing machine

Info

Publication number: US2219933A
Authority: US
Priority date: 1938-12-20
Filing date: 1938-12-23
Publication date: 1940-10-29
Anticipated expiration: 1957-10-29
Also published as: GB537411A; FR862401A; DE704739C; CH215920A; GB524148A; US2200402A

Description

Oct. 29, 1940. R MORRlLL 2,219,933

SHOE SEWING MACHINE Filed Dec. 23, 1938 Patented Oct. 29, 1940 UNITED STATES SHOE SEWING MACHINE Alfred R. Mfll'l'ill, Beverly, Mass., assign United Shoe'Machinery Corporation, Bo 'ugh of Flemington, N. J., a corporation of New Jersey Application December 23, 1938, Serial No. 247,460

90laims.

The present invention relates to improvements in shoe sewing machines, and more particularly to improvements in thread handling devices adapted for use in inseam chain stitch sewing machines employing a curved hook needle, 2.. looper, a take-up which acts to pull the thread with a stitch setting strain around the shank of the needle while engaged with the work, and a thread tensioning device which serves to assist the thread handling devices in the proper handling of the thread, particularly during the-operations of tightening and setting the stitches.

Applicant's invention is intended primarily as an improvement in the thread handling devices illustrated and described, for example, in his prior Patent No. 1,971,575, dated August 28, 1934. The improvement consists specifically in the provision of a tension control which acts during the operation of the needle in tightening the preceding needle loop, to 'maintain a light tension on the thread, and then during the stitch setting stroke of the take-up, to produce a gradual in- ,crease of the thread tension to cause the stitch to-be firmly set under the full stitch setting 25 strain-without danger of breaking the thread.

Specifically, it is an object of the invention to provide an improved thread tensioning device adapted for use in a machine of this description, which will cause the thread handling devices to function smoothly and accurately to firmlyset each succeeding stitch, and which will operate equally Wellfor slow and for extremely high operating speeds of the machine.

It is a further object of the invention to provide a thread tensioning device including a tensionwheel and friction means acting on the tension wheel to tension the thread, which will eliminate any harsh or jerky action in starting the wheel during the loop drawingstroke of the needle and during the stitch setting stroke of the take-up, and will at the same time enable the take-up to set the stitch against a heavy tension which may be regulated to the same maximum value consistent with the strength of the thread and nature of the work beingoperated upon for a wide range of operating speeds of the machine. While applicants improved form of thread handling mechanism including a thread tension gradually variable from a minimum to amaximum value during movement of the take-up lever between its retracted position in which the loop drawing stroke of the needle is completed and its-advanced stitch setting position, has the advantage above stated, that adjustments of the tension by the operator are rendered unnecessary over a wide range of operating speeds, such adjustment is nevertheless desirable to adapt the machine for operation at extreme high speeds which may be in excess of 1000 revolutions per minute. It is a further object of the invention to provide a variable thread tension of this general description having means for adjustment in which the tensioning device and the adjusting means associated therewith are so constructed and arranged as to provide a correct proportional adjustment of the tension for each of its maximum and minimum values, whereby a tension of predetermined strength is placed on the thread during the stitch setting stroke of the take-01f lever, and a proportionally, lighter tension is placed on the thread during the loop drawing stroke of the needle. I

It is still another object of the invention to provide an improved tensioning device adapted for use in thread handling mechanism of the general typereferred to, which will be extremely simple, and at the same time efiective in operation to insure the formation of a tight regular seam.

With these and other objects in view as may hereinafter appear, a principal feature of the invention consists in the provision with a thread handling mechanism of the general type referred to, including a tensioning wheel, and frictioning means therefor, of means acting in timed relation to the movement of the take-up lever to gradually increase the strength of the friction from a relatively small to a maximum value as the take-up lever approaches the limit of its stitch-setting stroke.

Another feature of the invention consists in the provision tin a machine of this general description, of which the thread handling mechanism includes with a curved hook needle and a take-up, a thread tension gradually variable from a minimum value for a position of the parts in which the loop drawing stroke of the needle is completed, to a maximum value as the take-up approaches its advanced stitch setting position, of a calibrated expansible and contractible spring means for exerting said variable tension, and adjusting means cooperating therewithi whereby changes in said adjustment will effect similarly proportional adjustments of the pressures exerted by the spring in each of its expanded and contracted positions.

The several features of the invention consist also in the devices, combinations and arrangement of parts hereinafter described and claimed,

which together with the advantages to be-obtained thereby, will be readily understood by one skilled inthe art from the following description 4 taken in connection with the accompanying drawing, in which Fig. 1 is a view in left side elevation showing a portion ofthe sewing head of a curved hook needle chainstitch sewing machine adapted for sewing together the inner solehnd upper, or sole, upper and welt, only so much of the machine being shown as is believed 1o necessary to illustrate the connection of the present invention therewith, this figure showing the parts in position with the needle substantially at the limit of its retracting or loop drawing stroke; Fig. 2 is a view similar to Fig. 1, but showing the parts in position at the limit of the stitch setting stroke of the take-up to set the stitch against the shank of the needle while engaged through the work; Fig. 3 is a detail plan view of the tension wheel and friction brake mechanism associated therewith shown in Figs. 1 and 2; Fig. 4 is a detail plan view showing the position of the needle and looper with the needle loop drawn through the work substantially in the position shown in Fig. 1; and Fig. 5 is a detail plan view showing the needle and looper in the positions taken in Fig. 2, to illustrate the setting of the stitch against the needle shank, the subsequent position of the looper and thread after the looping of a new bight of thread about the shank of the needle being shown in this figure in dotand-dash lines.

The shoe machine illustrated in the drawing, is adapted for sewing the upper and the welt to the insole of a welt shoe, and is provided with the usual operating elements of a welt sewing machine comprising a curved hook needle, a curved awl, a looper, a thread arm, a take-up, a welt guide, a channel guide, and a back rest.

The construction and operation of the stitch forming devices is substantially the same as that described in applicant's prior Patents Nos. 1,920,998 and.1,971,575. The thread take-up and tensioningdevices of the machine, the improvement in the control and operation of which forms specifically the subject-matter of the present invention, except as hereinafter specifically set forth, are substantially similar to that illustrated, for example, in the latter of the two prior patents above mentioned.

Referring specifically to the drawing, in which the several cooperating instrumentalities, for convenience of illustration, are given the same reference numbers as in the above-mentioned Patent No. 1,971,575, the curved hook needle is desigu' nated at l, the awl at Ii, the looper at 8,the thread finger at III, the take-up lever at I2, the welt guide at I4, the channel guide at I8, and the back rest at 20.

The operation of the thread handling devices 60 in the illustrated embodiment of the invention,

' difl'ers from the operation of those described and illustrated in applicant's prior patents above noted, in that the auxiliary take-up action of the take-up lever I2 is entirely eliminated, the takeup lever being at all times positively actuated by its operating cam, which comprises a closed cam track 2I formed in the usual cam disk 22, and into which is fitted the cam roller 23 carried on the rear end of the take-up lever I2. With this con- 70 struction and arrangement of the take-up lever and its actuating cam, the take-up lever is moved positively to its extreme loop setting position, and then positively downwardly to give up thread in timed relation to the operation of the thread finger, looper and needle.

The thread leading from the supply is tensloned as inthe patent above referred to, by means of a tension wheel I18, the thread being arranged to pass over'the tension wheel I18 and thence downwardly around a stationary thread truck 24, over 5 a thread truck 25 on the take-up lever I2, and thence downwardly through the,looper 8 to the work. Further, as in the construction above referred to, the, tension wheel I" is secured to a rotatable pin herein designated at 26 supported l0 in a stationary bearing 28, and having also mounted thereon a friction drum I80. The parts of the thread tension as thus far described, are identical with corresponding parts illustrated in the Morrill Patent No. 1,971,575 above referred to. 15

In order that the application of the present invention thereto may be readily understood, the mode of operation of the thread handling mechanism employed, may be briefly stated as follows,-Beginning with the position shown in Figs. 20 1 and 4, in which the needle has been moved to the limit of its withdrawing stroke to draw a new loop of needle thread 30 through the work, and in which the work has been advanced, the needle is now advanced through the work to the position 25 shown in Fig. 5, and the take-up lever I2 is moved positively under the influence of its operating cam, to the fully raised position shown in Fig. 2, thus causing the last loop of needle thread 30 to be pulled tightly against the shank of the needle 30 4, and a stitch setting strain to be exerted in the seam against the tension provided by the tension wheel I18, which is at this time started sufficiently to draw off from the supply an amount of thread equal to that consumed in the forming of 35 the previous stitch. Following this action of the take-up, the thread finger III is actuated to draw off a suflicient amount of thread between the needle 4 and the previously formed stitch, so that reeving .of the thread through the needle hook 40 is prevented during the subsequent retracting or loop drawing stroke of the needle, and the looper is actuated to place the thread about the needle 4 as indicated in dot-and-dash lines in Fig. 5.

During these operations, the take-up lever I2 is 45' moved downwardly giving up thread. This downward movement is continued during the retracting movement -of the needle through the work. Slightly before the needle reaches its fully retracted position, as shown in- Fig. 4, the down- 50 ward movement of the take-up lever is arrested, causing the new needle loop to be drawn tightly against the resistance provided by the thread tension, and causing the tension wheel I18 to be started slightly. This loop drawing stroke of the 55 needle acts to tighten the loop 30 of the previously formed stitch around the two legs of the loop now in the needle, duplicating the position of the parts shown in Fig. 4.

It will be understood that while in the illusa yielding auxiliary take-up action is employed.

With the usual construction and arrangement of the thread handling devices of these machines operating as above set forth, it has been custom ary to employ. a thread tension of constant value 7 heretofore been customary, difficulty has been experienced in' securing an adjustment of the friction brake acting on the tension wheel I18 which is adequate to insure the formation of a tight stitch without at the same time causing thread breakage. Such thread breakage'is most frequently caused in high speed operation of the machine during the stitch setting stroke of the 'ation. invention, it is proposed to employ a calibrated take-up lever by the relatively greater strain against or jerking of the thread required to start the tension wheel I18 against the continuously applied friction, the usual heavy and uniformly applied thread tension tending to prevent the starting of the wheel I18 until all of the thread employed in the making of the previous stitch is used up, and as the take-up lever I2 approaches the limit of its upward or stitch setting stroke. In order to eliminate this difficulty, and at the same time to provide a thread tension which .will be adequate to insure the proper operation of the machine throughout the entire range of operating speeds, applicant proposes to employ a variable tension which may be graduated from a relatively small to a maximum value in direct proportion as the take-up lever I2 moves from its low'to its high stitch setting position.

With the form of thread handling mechanism herein specifically described. in which the takee up lever is at all times positively controlled. and in which it is proposed to adjust the operation of the cooperating parts to cause the needle loop to be drawn in against a preferably yielding tension supplied by the tension wheel, applicants variable thread tension is employed with advantage to produce the relatively lighter tension desirableduring the loop drawing stroke of the needle, and thereafter a gradually increasing tension during the stitch setting stroke of the take-up. In the illustrated construction, the variable tension desired is produced by the compression or expansion of a coil spring which is arranged to exert a frictionally engaging pressure on a friction brake, a simple adjustment being provided for predetermining the amount of frictional pressure desired within the limits of expansion and compression during machine oper- In accordance with-one feature of the these pressures will, for example, increase the I pressures exerted to five and .ten pounds respectively.

In the illustrated embodiment of the invention, the brake shoe I82 is nivotallv mounted at. an nn 8. short lever arm 42 carried on a sleeve hub 44 ona stationary pivot pin 48, and is urged against the friction drum I by means of a calibrated compression spring 48 seated at one end against a pin 48 on the take-up lever I2, and at its other end against a collar 58 on an adjustable set screw 52 screw-threaded into a horizontally extending arm 64 formed on the sleeve hub 44. With this construction it will readily be seen that the upward movement of the lever I2 will act to compress the spring 48, and thus to gradually increase the frictional pressure exerted by the friction shoe I82 against the friction drum I88, the downwith the operation of the thread handling devices above set forth as follows,-'the take-up lever I2 moving downwardly to-give up thread with the retracting movement of the needle through the work, reaches its extreme low position slightly before the needle finishes its loop drawing stroke,

so that the needle loop is finally drawn In against A the tension provided by the tension wheel I18,

this being the position of the parts shown in Figs. 1 and 4. For this position of the take-up lever I2, the spring 48 will have been moved to its fully expanded position, so that a relatively light braking friction is exerted at this time upon the tension wheel I18. As the needle is moved downwardly through the work to the position shown in Fig. 5, and as the take-up lever I2 starts its upward movement, the braking friction on the tension wheel I18 is gradually increased. Under relatively slow speed operating conditions of the machine. this gradual increase in the braking pressure on the tension wheel I18 will be ade-- quate to prevent premature starting of the wheel I18, which will nevertheless be more gradually started as the take-up lever I2 approaches the extremely rapid upward movement of the takeup lever I2 introduces a new factor in the greatly increased frictional resistance to the drawing in of the thread, and more particularly to the starting of the tension wheel I18 against the friction exerted by the brake shoe I82, the relatively light frictional strain exerted by the spring 48 during the earlier portions of'the upward movement of the take-up lever I2, will permit a relatively easier starting of the tension wheel I18 which will take place more gradually and at a still earlier point in the upward movement of the take-up lever I2. In any event the final setting of the stitch as the take-up lever I2 reaches the limit of its upward movement, will take place against a maximum resistance of the thread tension. Under these conditions, any tendency to the exerting of a sudden and excessive strain on the thread or onthe work, through the operation of the thread handling devices in setting the stitch, is avoided, and it becomes possible to per mit a relatively close adjustment of the tension exerted by the spring 46 to the desired maximum valm: inr the final aHhm anti-an" m r..u.. m...

.pressed position of the spring, in which the takeup lever i2 approaches the limit of its upward or stitch setting stroke.

With this construction and mode of operation of the thread tension, it will readily be seen that the strength of the thread tension against which the stitch is set, is to a considerable extent independent of the speed of operation of the machine, and may be adjusted by the operator with reference to the strength of the thread andthe requirements of the work being operated upon to produce uniform tight stitching, and with a minimum compensation for variations in inertia or other factors introduced by variations in the speed at which the machine is operated.

It will be understood that the invention is not limited to the specific embodiment shown, and that various deviations may be made therefrom without departing from the spirit and scope of -H the appended claims.

What is claimed is: Y n

l. A chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curved hook needle, a looper, and a I take-up acting to pull the thread tightly around the needle while theneedle is.in the work, and to pull additional thread from-the supply, thread tensioning means, and means operative during the thread pulling movement of the take-up to increase the tension applied against the thread by said tensioning means from a relatively small value to a maximum value as the take-up reaches the limit of its thread pulling movement.

2. A chainstitch inseam shoe sewing machine the movement of the take-up to pull in the thread.

3. A chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curved hook needle, 8. looper, and a take-up acting to .pull the thread tightly around the needle whilethe needle is in the work, and to pull additional thread from the supply, a variable thread tensioning means for tensioning the thread comprising a tension wheel, and means actuated by said take-up and actingon s'aid variable tensioning means during the thread pulling movement of the take-upgto gradually increase the tension on the thread to a maximum value subsequent to the starting of the tension wheel in pulling thread from the supply;

' 4. A- chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curved hook needle movable to draw in a loop of needle thread, a looper, a thread a thread tensioning means including a friction device, a spring connected between the friction device and the take-up lever arranged during movement of the take-up lever in a take-up direction to gradually increase said friction, and during movement in an opposite direction to gradually decrease said friction.

6. A chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curved hook needle, a looper, a takeup lever, and means for positively actuating the take-up lever to give up-thread to the looper and needle, and thereafter to pull the thread tightly around the needle while the needle is in the work, and to pull additional thread from the supply, a thread tensioning-means including a tension wheel and tensioning friction means acting thereon, and means to vary the frictional resistance exerted by said friction means in timed relation to the movement of the take-up lever, constructed and arranged to reduce said frictional resistance to a predetermined minimum value during said thread giving motion of the take-up lever, and thereafter to gradually increase said frictional resistance to a predetermined maximum value at the limit of said thread pulling motion of-the take-up lever.

'7. A chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curvedhook needle, a looper, and a take-up lever movable to pull the thread tightly around the needle while the needle is in the work, a thread tensioning means including a friction device, a spring connected between the friction device and the take-up lever arranged during movement of the take-up lever in a takeup direction to gradually increase said friction, and during movement in an opposite direction to gradually decrease said friction between predetermined maximum and minimum limits, and means for adjusting said spring tension, said spring being calibrated so that adjustment thereof will produce proportionately correct adjustments of both the minimum and maximum values of the tension on the thread.

8. A chainstitch inseam shoe sewing machine having, in combination, thread handling devices including a curved hook needle, a looper, a thread finger and a take-up movable to give up thread and thereafter to pull the thread tightly around the needle while the needle is in the work, a

thread tensioning means including a friction device andan expansive and contractible spring acting on said friction device, means acting on said spring for controlling said thread tensioning'meansto-cause the needle to draw its loop ,against a minimum tension and thereafter to gradually increase the tension to a maximum value during the stitch setting stroke of the takeup lever, and means for'adjusting said spring to vary the tension exerted thereby, said spring being calibrated so that adjustment thereof will produce proportional adjustments of both the maximum and-minimum values of the tension ment of the take-up to gradually increase the tension on the thread exerted by the thread tensioning device from a relatively small value and reaching a maximum value subsequent to the starting of the tensioning device by the take-up 6 in pulling thread from the supply.

ALFRED R. MORRILL.