US136314A - Improvement in sewing-machines - Google Patents

Description

0. FARRAR'.

Sewing-Machines.

Patented Feb. 25,1873.

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AM. PHOTO-LITHHGRAPHIC ca Mr (mam/v53 rnacsss) PATENT Curran;

OSCAR FARR-AR, OF CHICAGO, ILLINOIS.

IMPRGVEMENT IN SEWING-MACHINES.

Specification forming part of Letters Patent No. 136,314, dated February 25, 1873.

To all whom it may concern.-

Be it known that I, OSGAR FARRAR, of Chicago, in the county of Cook and State of Illinois, have invented certain Improvements in Sewing-Machines, of which the followin g is a specification:

My invention relates to that class of machines in which a rotating hook is employed to carry the needle-thread over a bobbin containing the under thread-such, for example, as the well-known Zheeler & Wilson machine; and the objects of the invention are to provide a loop-cheek for the upper thread which shall be yielding but positive in its operation; to prevent the gradual increase in the tension of the lower thread, which takes place in the present machines, as the thread is used from the bobbin; to furnish better means for regulating the tension of the under thread; and to accomplish other minor results, as hereinafter explained. The invention consists in the employment of a bobbin case or carrier of peculiar construction provided with a loop-check for the upper thread, with tension devices for the under thread, and so shaped as to facilitate the passage of the upper thread over it and also consists in providing the rotatin g hook with an eccentric recess to receive the bobbin and case in order to move them edgewise.

Figure 1 is a face view of the rotating hook, with my bobbin-case and the bobbin in place therein; Fig. 2, an inside face view of the slide ring which holds the bobbin and bobbin-case in place in the recessed side of the hook, show-' ing the shoulders or projections which limit the rotary or rocking movement of the bobbincase; Fig. 3, a vertical central section through the rotating hook, with the bobbin-case and bobbin in place therein; Fig. 4, a vertical central section through the rotating hook, showing the squareedged recess to receive the bobbin-case; Fig. 5, a bottomedge view of the bobbin-case, Fig. 6, a vertical central section through the bobbin-case turned upside down; Figs. 7 and S, diagrams showing, respectively, the manner in which the bobbin-thread passes to the fabric and the eccentricity of the recess in the rotating hook; Fig. 9, a top-edge view of the bobbin; Fig. 10, a face view of the rotating hook, with the bobbin and its case in position 5 Fig. 11, an inside face view of the bobbin-case, bobbin, and a portion of the rotating hook, illustrating the manner in which the upper threadpresses the bobbin sidewise so as to causefriction thereon, and assist in producing the tension of the under thread,

which is provided on its end'withthe rotating hook B to hold thebobbin and carrythe needlethread around the same. The hook may be constructed in any suitable manner; but inthe present instance I have represented the hook of the Wheeler 86 Wilson machine, having a recess or cavity in its outer side to receive the.

bobbin. 0 represents the bobbin, made in the usual lenticular form to'fit within the recess in the side of the'hook. 1) represents my bobbin-case, which consists of a light metal shell, made of a concave form so as to cover one side of the bobbin and encircle the outer edge of the same, and provided on its inside with a central stud or pivot, d, for the bobbin to turn upon. The recess. in the side of the rotating hook B is made of such size that it will admit not only the bobbin but the edges of the bobbin-case also, as shown in Fig. 3, so that the hook'carries the loop of the upper thread around both bobbin and bobbin-case. The

bobbin-case is held in place in the hook bymeans of a ring-slide, E, which is fastened against the outer, side of the case, as shown in Fig. 13, in the same manner that it is ordinarily used to hold the bobbin in place in the Wheeler & Wilson machine. The edges of the recess in the hook which receives the bobbin-case are made square, or at right angles to the face of the hook, as shown att,

Figs. 3 and 4, so that there is no tendency of the case to work out or to wedge fast when the bobbin-thread draws edgewise upon it. W hen wise and wedging fast, as it would otherwise do. The bobbin-case is not intended to rotate,

except to a slight extent back and forth. "In' order to limit its movement two openings,g,

areinade in its side so as to leave a bar, 7:, between them, as shown in Figs. 1 and 13, and then the ring-slide provided with 'two shoulders or projections, f, as shown in Fig. 2, which enter the openings on opposite sides of the bar, as shown in Fig. 13, so that the case can only rotate or rock back and forth until the bar It comes in contact with one or the other of the shoulders on the ring-slide. On the lower outer side of the bobbin-case, in rear of the center, Iform a hook or horn, 0', which serves to check the loop of the upper thread, and takes the place of the brush-ch eck used in the Wheeler 8: Wilson machine. When the machine is in operation the loop of the upper thread, passin g over the case I), is caught and held by the hook or check 1' until the continued rotation of the rotating hook casts it off therefrom. The shape of the check 0 and the arrangement of the rotating hook are such that the loop is cast off at the instant the rotating hook enters the next loop of the needle-thread. As the loop of the needle-thread tightens up '-'"and draws upon the check-hookrthe bobbin-case turns forward and allows the check-hook to riseuntil the strain onthe needle-thread is-re-. lieved. By thus arranging the check-hook so that it will yield under the strain of the upper thread I obviate all danger of unduly straining said thread. After the bobbin-case has been turned forward by the loop of the needle-thread drawing upon the check-hook r it is turned back again by the action of the un-- der thread, which issues from the front side of thebobbin-case and passes backward and upward, as hereafter explained. The bobbincase I'provide in its lower edge with a hole, 2', and in its upper edge with a number of holes, j, all but one of which latter are forward of the center. The bobbin-thread I pass out through the hole 27, and then up through one of the top holes j, whence it passes to the fabric, as shown at G, Figs. 1 and 10. When the bobbin-case is turned forward by the strain of the upper thread on the cheekhook, as before described, sufficient thread is unwound from the bobbin to form .the next stitch. The manner in which this is done will be readily seen by reference to Fig. 7, in which n. represents the point at which the thread issues before the bobbin-case is turned forward, and 0 the point at which it issues after the case is moved. A certain length of thread extends from the hole at 'n to the stitch being formed at the needle; but as the bobbin-case turns forward the hole recedes from the needle, so that an increased length of thread is required to extend from the hole to the needle, and the thread is consequently caused to unwind from the bobbin. The thread thus unwound and drawn out is, as before stated, suflicient to form the next stitch. The loop of the upper thread, after being cast off from the check-hook r, is drawn up by the needle so as to draw the bobbin-thread up into the fabric. When the needle-thread thus draws upon the bobbin-thread, which is just after the bobbin-case is turned forward to unwind the thread, the bobbin-thread is tightened up so as to turn'the bobbin-case back to the position in which itstood before it was turned forward by the action of the needle-thread against the check-hook. When the bobbin-thread is drawn up into thefabric no additional thread is drawn from the bobbin, but merely that which was unwound by the forward movement of the case taken up. The only resistance to the bobbin-thread being taken up is due to the -resistance which the bobbin-case offers to befabric, but is first unwound by "a separate, in-

dependent operation, and then its tension given by devices which offer a uniform resistance.

7 In the ordinary machines the tension increases because the thread is drawn from the bobbin direct, and the bobbindi'ers increased resist-i ance as the thread nears the center. The ten sion of the bobbin-thread depends upon the amount of resistance which the bobbin-ease offers. to being turned backward. This resist-I ance is due entirely to the friction of the case againstthe ring-slide, caused by the loop of the upper thread drawing against the inside of the bobbin and case, so as to press the case outward against the slide-ring. It therefore follows that the greater the tension of the upper thread the greater the friction of the case against the slide and its resistance to'being turnedbackward, and, consequently, the greater the tension of the bobbin-thread. This ac tion of the upper thread upon the tension of the lower thread is very similar to that in the Wheeler & Wilson machine, and is what is known in the trade as the automatic tension of the under thread. The tension of the under thread is also regulated by passing it through one or another of the holes j in the bobbin-case. When passed through one of the holes near the needle it drawsnearly in line with the center of the bobbin-case, and at a great disadvantage, so that a strong tension is produced on the under thread in drawing it back; but, when passed through the holes at a greater distance from the needle, it has a greater leverage, and turns the case back with more ease, and therefore less tension is produced on the thread. By passing the thread through a hole very near the needle a tension may be produced sufficient to keep the under thread straight on the under side of the fabric, although a strong upper tension be also used. This arrangement will be found very valuable in working button holcs.

As a further means of causing a tension on the lower thread, I secure within the bobbincase a flat spring, 70, having in one end an eye or hole through which the thread is passed, as shown in Fig. 6, so that the spring bears upon it. The end of the spring I provide with a lip, a, which projects out through the side of .the bobbin-case, as shown in Figs. 1, 5, 6, and 10, so that when the loop of the upper thread engages on the check-hook 1' it bears on the lip and raises the spring so as to relieve the tension of the under thread for the moment. By thus relieving'the tension I permit bobbin-case to turn easily under the action of the needlethread loop, so as to obviate all danger of straining said thread. This spring is not, however, an essential feature, and it may be dispensed'wit'h; or it may be used without the lip 12 either in the bottom or top of the bobbincase, as preferred.

In order to facilitate the passage of the needle-thread around the bobbin and bobbin-case, the recess in the rotating hook to receive the bobbin-case is made slightly eccentric to the centers of the hook and'slide-ring, so that it moves the bobbin and case edg'ewise in a circle eccentric to the slide-ring. The movement is so timed that the bobbin-case is drawn back from the ring-slide just in advance of the upper thread-loop, as the latter passes around, so that an open space is left betweenthe bobbin-case and slide-ringfor the passage of the thread. The thread is thus allowed to pass through with far less strain than in the ordinary machines, in which the loop is required to force the bobbin and slide-ring apart. In order to further facilitate the passage of the loop, the inner edge of the bobbin-case is cut away or provided with a recess,"s, as shown in Fig. 9, so as to permit the thread to pass without binding. cilitating the passage of the thread, I make the rear edge of the bobbin-case wider or thicker than the front, so as to throw the rear edge of the bobbin outward, and permit the thread to pass down in a straight line from the upper edge of the hook behind the bobbin and around the point of the hook. This is not, however, shown in the drawing, and is not considered essential, although beneficial.

Referring back again to the manner in which the lower thread, when drawn into the fabric, turns the bobbin-case back to its first position, it should be observed that about as each stitch As a still further means of fa-' is being completed the tension of the bobbinthread increases. This is owing to the fact that the hole through which the thread issues approaches the needle so that the thread draws with decreasing leverage on the case. The increase of tension thus given to the bobbin-thread causes a strong and firm interlocking of the two threads.

By means of my improvements I provide a loop-check which never fails to detain the loop, and'never subjects the same to excessive strain. I give the bobbin-thread a uniform tension, notwithstanding the increasing resistance of the bobbin. I increase the tension of the bobbin-thread momentarily at the completion of thread tearing loose in light fabrics, or of the needle-thread being detained and caught a second time by the rotating hook.

Having thus described my invention, what I claim is- 1. The bobbin-case 'D, provided with the hook or check 1', arranged to operate substantially as described.

2. The bobbin-case D, provided with the recess 8, to facilitate the passage of the thread, as shown and described.

3. The bobbin-case D, provided with the spring k, having the lip a projecting through the case, substantially as shown and described.

4. The rota-tin g hook B, having its recess to receive the bobbin, arranged eccentrically substantially as and for the purpose described.

5. In a sewing-machine, a bobbin-case which is turned backward bythe bobbin-thread while said case is held under the pressure of the nee dle-thread, substantially as herein described.

6. The bobbin-case D, provided with the recess s,and with the hole or holes j in its upper side, as shown and described, and for the purpose set forth.

OSCAR FARRAR. Witnesses: I

E. A. EST, 0. W. BOND.

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