US2436782A - Lock stitch sewing machine - Google Patents

Description

G. J. BARBATI' .LOCKSTITCH SEWING MACHINE Filed Nov. 25, 1946 .menwr Patented Mar. 2, 1948 OFFICE LOCK STITCH SEWING MACHINE Guido J. Barbati, Beverly, Mass.,

United Shoe Machinery Corporation,

assignor to Flemington, N. J a corporation of New Jersey Application November 23, 1946, Serial No. 712,005

3 Claims.

The present invention relates to improvements in lock-stitch sewing machines and is herein disclosed as embodied in a hook needle shoe sole sewing machine of the rotary horn type in which each loop of needle thread is pulled from the shuttle partially back toward the upper surface of the work by a take up, enough slack thread being left remaining in the loop outside the work to provide thread for one side of the needle loop in the next succeeding stitch. The threaded needle, as it is moving within the substance of the work, therefore does not cause the thread to slide and become frayed within its hook.

The object of the invention is to provide simple means for enabling easy adjustment of such machine for optional use with relatively thin or thick work. When relatively thin sewn, a shorter needle is employed than with thicker work. The use of a shorter needle is desirable to enable the needle to be more resistant to bending stresses, particularly where a needle of smaller wire gage is employed. For thicker work, a needle of larger gage is employed and, consequently, it is possible to use one having a greater length without losing stiffness. In either case, however, the needle is reciprocated through a fixedstroke, the needle hook moving the same distance toward and away from the work supporting horn of the machine. When thicker work is being sewn, however, the length of the needle 100p left remaining outside the Work after the take up acts is less than with thin Work and, in some instances, may not be suiilcient to enable the threaded hook of the needle to move through the substance of the work without causing the thread to slide in the needle hook.

Accordingly, in carrying out the object of the present invention, a readily removable shim is provided between a bracket for supporting the shuttle and the upper portion of the column on which the entire machine is mounted, so arranged that as each needle loop is passed over the shuttle while the shim is in place sufiicient thread will be pulled from the supply to enable the threaded needle hook to be moved through thin work without causing the thread to slide in the needle hook. With the shim removed, for sewing thicker work, the shuttle will likewise pull off from the supply suflicient thread to enable the needle to move through the substance of the work without causing the thread to slide in the needle hook.

This and other novel combinations, and arrangements of parts, as hereinafter claimed, will readily be understood from the following de-- work is being i 2 scription taken in connection with the accompanying drawings, in which:

Fig. l is a view in right side elevation of so much of the upper portion of an improved shoe sewing machine as is necessary to illustrate the embodiment of the present invention;

Fig. 2 is a front detail view illustrating the manner in which the machine operates; and

Fig. 3 is a similar view of the shuttle and work supporting horn with the needle and needle supporting bar omitted.

The machine illustrated in the drawing is a lockstitch shoe sewing machine of a type similar to that disclosed in United States Letters Patent No. 1,885,927, granted November 1, 1932, upon application of Bernard T. Leveque, and No. 1,914,936, granted June 20, 1933, upon application of Fred Ashworth. In this machine a shoe or other similar work is supported upon a rotary horn 4 mounted on the column and arranged to extend within the shoe which is held in engagement with the horn by a presser foot 6 acting to grip the work while the stitch formingdevices act. The stitch forming and work supporting devices are mounted for operation upon a frame comprising a main column 1, the construction of which is more fully disclosed in the patents referred to.

The stitch forming devices comprise a straight needle 8, a loop taker in'the form of a shuttle I 0, acting to carry each loop of needle thread about a locking thread, a loop spreader I23 and a take-up l4 acting to pull each loop of needle thread together with the encircled locking thread from the shuttle partially back through the work with a portion l5 of the needle loop left remaining outside the work. After the take-up has acted, the shoe is fed in preparation for a new stitch formation and the needle again penetrates the work, entering the horn to receive a new loop of thread. During the succeeding retracting movement of the needle while its threaded hook is moving through the work, thread is drawn from the portion l5 of the preceding loop which remains outside thework so that no sliding movement of the thread takes place within the needle hook. In this way fraying and excessive wear on the thread are avoided. Thus, the loop from the preceding stitch is drawn nearly to the surface of the work by the needle. Thereafter, the loop spreader engages the loop of thread carried by the needle and spreads it for reception of the shuttle. The shuttle continues the withdrawal of the preceding loop of needle thread together with the encircled locking V by the enlarged shank v 2, when-the needle is in its position. With work:

, thread and pulls the interlocked threads into With the length of needle ordinarily employed in.

this machine, however, the upperlsurface of work thicker than of an inch frequentlyis engaged.

portion of the needle, indicated at I8 in'Fig. lowermost work penetrating approaching /8 of an inch in thickness thisenlarged, Shank. portion of the needle actually enters the work therebyejorming undesirable enlargements inthe needle perforations To avoid this difiicultyit s necessary toe oy a longer needle so that the enlar fid shank, l8 of the needle will not engagethe work, 7

As in the. patented ma-hinethe needle 8 is secured to the lower end of rec procating needle carrying, bar l9 to whichis clamped .an actuating block 20. To accommodate a, longer needle the needle bar must be raised withrelation to its reciprocating mechanism. This is accomp ed ve i tly inthe illustrated machine by loosening the clamp block 20 on the needle bar and moving the barwithin the block before reclamping: until the-hooked needle will occupy thesamelpositions at theupper and lower ends ofits strokeas did the shorter needle previously employed. Thus, during its retractingstroke, thehook of the needle inv the machine must rise and-fallto thesamepositions regardless of the length of needle employed or thethi-cknssof the work operated upon. The stroke of theneedle; however, isrampie -to take care of the thicknessof any work'upon which the machine is capable of operatingsuccessfully.

With work having a thickness greater than of an inch, the portion 15 of needle loop remaining outside'the workuin each preceding stitch is insufficient to provideslack thread for the needle during its retracting stroke inthe formation of a succeeding stitch. Forthisreason, with work thicker than /8 of aninch even with a longer needle, difiiculty still is encountered by reason of a sliding movement of the' thread-in the needle hookwhile the threaded needle; hook ispassing through the substance of, thework.

7 To provide simple and effective means for adjusting the machine for usewith work thicker than /3 of an inch, according-to afeature of the present invention, the shuttleiszarranged to pull through a greater length of theneedle loop when the machine is adjusted for-thick work'than for thin work. Forthis'. purposeitheshuttle is raised bodily when the machine-is-"beingadjusted'for thicker work to a position higher than when thin work is being operated upon. :Thus, each loop of thread is carriedover the shuttle, to a higher position and it is not drawn down as far as before during the thread-pulling-stroke of the take-up, but is left with a longer portion 45 remaining outside the work. Accordingly, when the thread- 7 ed needle is being retracted fromthe work in the succeeding stitch, there is ample slack thread left between the-needle and the previously formed of an inch.

[Work of of an inch lower end of the 7 is approximately stitch to prevent sliding movement of the thread in the needle hook.

To enable raising the shuttle bodily when thick work adjustments are being made, the shuttle is mounted to rotate in a bracket 22 clamped to the underside of the upper portion of the column for the machine but spaced therefrom by a readily removable shim 24 equal to the additional length of'the longer needle ordinarily employed while operating upon work thicker than /8 of an inch. In the embodiment illustrated, this shim of an inch thick, to enable the use of a needle of an inch longer which is effective for operation upon of an inch work ,to prevent engagement by the shank of the needle.

thickness is illustrated in'thedot-dash line'of Fig. 2 and with work of such thickness it is readily apparent that the portion l5 of needle loop left remaining outside the work when the machine is'adjusted for /8 of an inch work isinsuflicient toprovide slack thread for the needle during its retracting stroke.

The bracket 22 which-supports the shuttle also provides a mounting for the loop' spreader 82. Accordingly, when the shim 24 is removed, the loop spreader I2 is raised along with the shuttle to the dot-dash positions :of Fig. l'so that it retains itsproper relative relationship to the shuttle, thus acting effectively with the needle to open the loop for'the reception ofthe shuttle.

The loop spreader and shuttle being raised'bod- I ily when the shim 24 is removed cause the length of thread drawn thereby through the work to be increased by aniamount'double the increased length of the needle.

The nature andscopeof the inventionhaving been indicated and a machine embodying it having been specificallydescribed, what is claimed is:

1. A lockstitchsewing machine having a main column, the upper portion of which contains stitch forming devices including a hook needle acting While its threaded hook'is being'retracted from the work todraw thread from-the loop of needle thread in the-preceding-stitch, a-shuttle acting to pull off thread from the supply forthe next stitch, a take-up-forpulling each needle loop from the shuttle partially back through the work, a shuttle supporting bracket on the upper portion of the column and a shoe supporting horn mounted on the column to extendwithin the shoe, in combination with means for; enabling easy adjustment of the-machine tooptional'use for thicker work, comprising a readily removable shim between the shuttle supporting bracket and the upper portion of the column, to cause the shuttle to draw each loop of needle thread to a higher position relatively tothe horn for the thicker work.

2. A lockstitch sewing machine having a main column, the upper portion. of; which contains stitch forming devices-including a hook needle acting while its threaded hook is'being retracted from the work to draw-thread from theJoop of needle thread in-the preceding stitch, a shuttle acting to pull offxthread from the supply for the next stitch, a take-up for pulling each needle loop from theshuttle partially back through the work, a shuttle supporting bracket on theupper portion of the column and a shoesupport-ing horn mounted on the column to extendwithin the shoe, in combination with means for enablingeasy adjustment of the machine to optional use with a longer'needle'for thicker-work, comprising a readily. removable shim-between the shuttle supportingbracket andtheupper portion of the column, the thickness or said shim being equal to the additional length or the longer needle emplayed, to cause the length of thread pulled through the work by the shuttle to be increased by an amount double the increased length of the longer needle.

3. A lockstitch sewing machine having a main column, the upper portion of which contains stitch forming devices, including a straight hook needle acting while its threaded hook is being retracted from work to draw thread from the loop of needle thread in the preceding stitch, a shuttle acting to set the preceding stitch and thereafter to pull'oflf thread from the supply for the next stitch, a take-up for pulling each needle loop from the shuttle partially back through the work, a loop spreader for engaging each needle loop to spread it for entry of the shuttle, a shuttle and loop spreader supporting bracket secured to the under side of the upper portion of the column, and a shoe supporting horn arranged on the column to extend within the shoe, in combination with means for enabling easy adjustment of the machine to optional use for thicker work, comprising a readily removable shim between the shuttle supporting bracket and the upper portion of the column, for increasing the space between the horn on the one hand and the loop spreader and shuttle on the other hand, to cause the shuttle to draw each loop of needle thread to a higher position relative to the horn when the shim is removed for the thicker work.

GUIDO J. BARBATI.

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