US2426662A - Lock stitch shoe sewing machine - Google Patents

Description

Sept. 2, 1947. F. AsHwoR'n-l LOCKSTITCH SHOE SEWING MACHINE Filed April 25. 1946 f Zu/enfer Had .4MM/fi y Patented Sept. 2, 1947 LGCK STITCH 'SHOE SEWING MACHINE Fred Ashworth, Wenham, Mass., `assign'or `to United Shoe Machinery Corporation, Flemingtn, N. J., a corporation 1oit' New Jersey Application April 26, 1946, Serial No. `665,132

(Cl. i12- 38) Claims.

The present invention relates to lockstitchsewing machines and more particularly to improvements in needle guides for machines of the type disclosed in United States Letters Patent No. 2,329,691, granted September 21, 1943, upon an application led in the name of the presen-t inventor, which patent in turn discloses an improvement in a well-known type of machine disclosed in United States Letters Patent No. 1,169,909, granted February 1, 1916, also upon application of the present inventor.

As more fully explained in inventors patent rst mentioned, the illustrated machine has a rotary loop taker equipped with .a hook, the loop entering beak oi which carries each needle loop over a thread case and thereafter releases the loop of thread with a substantial length of lthe loop remaining outside the work. When sewing at high speeds, violent action is imparted to the released loop, causing it to whip in an irregular manner against any part of the machine happening to be within its range of movement. Frequent diiiiculty, encountered in the operation of the machine, occurs when the needle loop, after being released from the loop taker, Ystrikes the open hook of ythe needle and becomes stranded or broken as a result.

To transfer each loop of needle thread drawn through the work from the needle to the loop taker, the machine also is provided with a loop spreader which opens the needle loop within the path of the loop taker beak. Unless substantial tension is maintained at all times, during the operation of the loop spreader, the thread may wholly or partially escape from the hook of the needle so that the beak of the loop taker will not enter or the strands in the thread may become separated from each other, weakening the thread and causing enlargements which restrict uniformity in movement or handling of the thread thereafter. To avoid these diiculties, it has been the practice in some instances to adjust the operations of the needle and needle guide so that the barb on the threaded hook of the needle will be covered by the needle guide, thus trapping the thread Within the hook of the needle during the loop spreading operation. Unless adjustments are accurately and carefully made, the needle guide, which in the patented machine lits accurately with the diameter of the needle, may become wedged over the thread carried by the needle hook. Thus, some of the strands of thread may be disengaged from the needle or other injury to the thread may occur.

The objects of the present invention are to avoid the necessity of accurately adjusting the movements of the needle .and guide in a lockstitch machine of the type referred to and to provide a needle guide by the use of which there will be no opportunity for stranding or othervn'se in- 2 v juring the thread either while the loop c'ar "ed by the needle is being spread by the loop spreader or after being released from the loop taker.

In the illustrated form of the machine, the needle guide is provided with a collar surrounding the needle, of greater internal diameter than the needle, within which collar the threaded hook of the needle may enter without danger of injury to the thread. The needle and guide thus may be actua-ted to trap the thread within the needle hook while each needle loop is being spread for the loop taker and the needle 'loop freed from the needle hook only at the proper time. Freeing the needle loop is accomplished by a positive relative movement between the needle and guide, slight variations in movement between the two thus causing the threaded hook of the needle to be drawn to more or less extent Within the collar on the guide without jamming the thread between the guide and the needle. v"The collar on the guide also serves to guard the hook of the needle from contact with the lneedle loop after being released from the loop taker.

Other features of the invention reside in the combinations and arrangements of parts hereinafter described and particularly claimed, as will be clearly understood from the following specification and the accompanying drawings, inwhich Fig. l is a view .in front eleva-tion of va portion of a lockstitch sewing machine embodying the invention;

Fig. 2 is a detailed View in side elevation of the stitchforming devices of the machine of Fig. l, illustrating the relationship of the threads in the machine tothe work support and presser foot While clamping the Work, a needle loop being shown in its spread position;

Fig. 3 is a view of the same parts of the-machine taken after a spread loop has been-disengaged from the needle and engaged with the loop spreader;

Fig. 4 is a detailed view in front elevation of some of the same parts of the machine;

Fig. 5 is a further detail View on an enlarged scale, illustrating the manner inwhich the thread `is trapped within the needle hook by the needle guide; and

Fig. 6 is a perspective view of the needle guide employed in the machine.

Except as hereinafter described, the machine illustrated in the drawings is substantially the same as the machine of inventors patents above identified. The rotary hook is indicated at 2, the locking thread case at 4, the curved needle at 6, the needle guide at 8, and the rotary loop spreader at I0. The needle operates to enter the work indicated at I2 secured by the Work support I4 and a presser foot I6 and to receive Aa loop of thread within its hook and thereafter to retract with the loop carried thereby. When Y the threaded needle is in retracted position, the

rotary hook moves within the spread needle loop, the loop is carried about the thread case 4 and disengaged from the needle, as in Fig. 3. During continued rotation of the rotary hook, the loop is released from the loop taker while a substantial length of the loop remains outside the Work so that during high-speed sewing operations, rapid whipping movement is imparted to the freed loop which causes the loop to strike forcibly against surrounding portions of the machine and work.

As has been stated, the needle guide of the present invention is provided with a collar I8 formed integrally therewith and arranged to surround the needle. The collar` I8 serves a double purpose, rst, to trap the thread Within the needle hookwhile the loop spreader is actingand, second, to guard the needle hook from accidental contactr after the needle loop is released by the rotary loop taker from the thread case. To insure against injury to the threadin the threaded needle while the guide is moved over the barb ofthe needle to trap the thread in the hook, as illustrated in Fig. 5, the internal diameter of the collar I8 is enlarged toY a size su'iciently greater than the outside diameter of the needle to permit the thread to be drawn within the collar without jamming the thread excessively.

The mechanisms for actuating the needle and guide are the same as those disclosed in the earlier of the two patents referred to and include a needle actuating lever the hub of which is indicated at 20 in Fig. 1,'and a needle guide cam-actuated Ybell crank 22 formed with rack teeth engaging a pinion 24 Which indirectly drives a carrier 26 rotatable about ya stud 28 concentric with the movements of the needle. In order to'insure freeing of the thread from the hook of the needle at the proper time after being trapped by the collar I8 on the needle guide, the cam for actuating the bell crank 22 is properlyI formed to impart a positive movement to the bell crank, shifting the guide away from the barb -on the needle hook.

VTo guard the needle hook from contact with the needle loop after release .by the loop taker, the needle guide 8 is moved positively over the hook again after freeing the thread therefrom. VIn this way, ,the needle hook is kcovered bythe collar I8 and, if the disengaged needle loop, illus- Vtrated in Fig. 4, whips against the collar, no injury .to the thread will occur. Thek clearance space between the collar and the needle'is sufcient to receive Ythe thread without jamming it 4in case slight looseness in the actuating parts causes excessive movement of the threaded needle hook within the collar.

Having thus described ther invention,.what is lclaimed as new and desired to be secured by Letters Patent of the United States is:

1. A lockstitch shoe sewing machine having stitch forming devices including a curved hook needle, alocking thread case, and a loop taker until the thread carried by the; needle is engaged 4 to enable the hook of the needle toI be shielded by the collar without dangerot injury to the thread contained in the needle hook.

2. A lockstitch shoe sewing machine having stitch forming devices including a curved hook needle, a locking thread case, and a loop taker acting to pass each loop of needle thread about the thread case and to free the needle loop with a substantial length remaining outside the work,

vin combination with a needle guide provided with stitch forming devices including a curved hook needle, a locking thread case,'and a loop taker acting to pass eachloop of needle thread about the thread case and to free the needle loop with a substantial length remaining outside the Work, in combination with a needle guide provided with a circular collar of substantially greater internal diameter than the outside diameter ofthe needle, arranged in surrounding relation to the needle, to enable the hook of the needle tor'be'srhielded by the collar without danger of injury to the thread contained in the needle hook, and mechanism for actuating the needle and'guide to guard the needle hook while theneedle is disengaged from the work and to trap the thread Within the needleV hook `with the loop taker. Y

4. A lockstitch shoe sewing machine having stitch forming devices including a1 curved hook needle, a locking thread caseya loop taker acting to pass each loop of needle thread aboutthe thread case and to free the needle loop with a substantial length remaining outside the work, and a loop spreaderfor opening the needle loop for engagement by the loop taker, in combination vith'a needle guide provided with a circular colar of substantially greater internal diameter than the outside diameter of the needle,.surrounding the needleto enable the threaded hook of the needle to enter within the collar without danger l ofV injury to the thread rand to trapthe thread within the needle Vhook until after the loop of thread vformed by the needle is spread and engaged withthe loop taker. Y

anda loop spreader for opening the needle loop for engagement by the looptaker, in combinal Y tion with a needle guide provided with Aa circular collar of substantially greater internal diameter than the outsidev diameter of Y theneedle, vsurrounding the needle to enable the threaded hook of `the needle to enter Vwithin thefcollarv without danger of injury to the thread and to'trap the thread within the needle hook until after the thread after theloop is engaged by the loop taker.

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