US527407A - Alfred w - Google Patents

Description

(model.)

A W COCHRAN KNOTTER POR SEWING MACHINES.

Patented Oct. 16,1894.

UNITED STATES ALFRED W. COCHRAN OF NEW YORK, N. Y.

KNOTTER FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 527,407, dated October 16, 1894.

Application tied August 8,1893. seritinaisasi. (Model.)

j To` all whom it mwyconcern:

4Be it known that I, ALFRED W. COCHRAN, a citizen of the UnitedStates, residing in the city and State of New York, have invented an Improvement in Knotters for Sewing-Machines, of which the following is a specification.

In Letters Patent No. 453,730, granted to me June 9, 1891, a knotter is represented having two spring arms and located between the two sides of a throat plate, so that by the rotation of the twister the lower or shuttle thread is twisted into a loop through which the needle passes, and then the shuttle thread is passed through the loop of needle thread and as the threads draw up, a knot is tied between the shuttle thread and the needle thread closely adjacent to the under side of the fabric that is being sewed. In my present invention a similar knot is tied, but I have simplified the parts so as to lessen their expense and also to render the operation more positive and reliable.

I construct the twister with jaws, the eX- terior surfaces of which when the jaws are `closed form a cylinder between theupper and lower parts of the throat plate, and by the act of rotating the twister the spring-jaw is closed against the rigid jaw around the thread, by the pressure of said spring-jaw against one wall of the opening in the throat-plate, anda cam-slot andpin are provided for drawing back the jaws after they have been closed to seize the thread, in order that the parts of the loop may interlock at the end of the twister, and then the twister is moved forward again and opens by the spring jaw to spread the twisted loop and hold the same `for the passage of the needle, after which the shuttle is passed through the loop of needle thread and the twisted loop of shuttle thread draws off the twister and is around the nee- 'dle and draws up closely against the under the parts, also partially in section. Fig. 3 is a perspective view showing the twister as detached from the throat plate and open to spread the loop, and Fig. 4 shows the twister as closed and revolved halfway around. Fig. 5 is a diagram of the knot. Fig. 6 is a cross section, at the line w, Fig. l, and Fig. 7 is an elevation of the button head of the twister;`

The throat-plate A, is preferably formed of j a piece of metal sufficiently thick for a hole to be bored therein longitudinally and parallel with its upper and lower surfaces and an opening extends from this hole laterally to the edge of the plate thereby forming an upper plate 2, and a lower plate 5f, which are perforated with holes for the passage of the needle, and the` twister B is formed of substantially a cylindrical wire filling the hole in the throat plate and having a button or head C at the outer end, and this button or head C is advantageously circular except that the upper part thereof should be cut off at the same level as the top surface of the throat` plate so as not to interfere with the fabric that is being sewed as the same lies upon the surface of the throat plate, and by providing a notch at 4 in the end of the head, the twister may be rotated by inserting the nail in the notch 4, pressing the twister inwardly against the action of the helical spring D that surrounds the outer part of the twister shank, and in so doing the circular portion of the head C is brought above the surface of the sewing machine table and can be rotated by pressure of the linger, so that it revolves once in twisting the thread, as hereinafter described.

The throat plate (A) may be secured to the bed of the sewing machine in any convenient manner. Usually it is attached to the plate (A) that is screwed to the bed of the sewing machine and has the openings for the feed bar asusual. Across the projecting end of the throat plate is a diagonal slot or mortise at 5 within which is a pin 6 upon the shank of the twister; and it will be observed that this pin 6 as the twister is rotated and the pin travels in the slot 5 gives to the twister an end movement bodily and then forces the twister back again into its normal position, and by providing an offset or notch in the slot 5, as at 7, the twister is stopped each rotation in the proper position by the pinG passing into said notch or offset at the com- IOO ceive its rotation.

pletion of the rotation, and the twister has to be pushed inwardly against the action of the spring D before the pin 6 will clear the offset 7 and hence before the twister can re This insures the inward movementwhich is advantageously given to the twister ir the act of grasping the thread. Through the upper and lower sides 2rand 3 of the throat plate there are the holes 8 and 9 ro for the eye-pointed needle to pass through, and

these are in such a posit-ion that the jaws of the twister are at opposite sides of the needle as it passes through the holes; and it is to be understood that this throat plateY is se-V cured to the sewing machine but with the upper surface of the throat plate on the level or nearly so` of the sewing machine bed and hence that the shuttle thread passes up through the holes 8 and 9 as the lock stitch zo is drawn up or tightened in the fabric, and

3o forms a spring that tends to open the jaw end of the twister, and the exterior surfaces of the jaw ends of the twister are semi-cylindrical, and the opposite adjacent faces of the jaw ends are recessed so that when the jaw 3 5 ends are brought together as in Fig. 4, there is an elongated mortise for the thread, and upon the spring jaw of the twister is a hook i' 11' having its pointextending inwardly toward the mortise, and in the rigid side of the 4o jaw is a groove l2 running outwardly from the mortise; and it will also be observed by Fig. 6 that the lower eye or hole 9 through H.the lower side 3 of the throat plate is elongated and beveled toward the rigid jaw, the

object being to prevent clamping and cutting the thread when the parts are rotated in twisting the shuttle thread. It is now to be understood that when an end motion is given to the twister, as before described, Vit passesVY 5o'toward the shuttle thread as the same extends through the two eyes or holes 8 and 9 of the throat plate, and as the twister is rotated the spring jaw thereof is closed by the semi-cylindrical surface thereof sliding on the lower plate as the twister is rotated between the upper and lower sides of the throat plate, and the twister is closed so that the thread is within the elongated slot of the twister.- In this position the ends of 6o the mortise through the twister extend as far as the edges of the eyes 8 and 9, so that the thread cannot be caught between the surfaces that come together but is free within the mortise, and as the rotation proceeds the twister is also drawn back by the action of the diagonal slot and pin and one part ofthe thread passes into the groove of the hook 1l and the other part of the thread passes out through the groove l2, as seen in Fig 4, and the twister draws back sufficiently for the Ytwo parts of the thread to twist together and of the hole 8,Y and out of the way of the de- Y scending needle, and the portion of the loop of thread that passes across from one hook l2, to the other hook 1l, is near the other edge of the hole 8, so that the needle passes freely through the loop. The loop of needle thread is passed around theshuttle or the shuttle passed through the loop, as illustrated in Fig. 5, so that the twisted loop of shuttle thread draws off the twister by the tension and is around such eye-pointed needle and is shed oft' the needle against the under side of the fabric that isbeing sewed as the needle draws up and the needle thread is drawn up, by the action of its tension, through the twisted loop of shuttle thread until the threads tighten and a knot similar to a sailors knot is tied closely adjacent tothe under side of the fabric that is being sewed. i

Itwill be observed that the metal of the throat plate that is adjacent to the rigid side of the twister when the twister is in the normal position shown in Fig. l, keeps the spring side of the twister closed up against the rigid sideY of the twister when the parts have been half rotated, as indicated 4in Fig. 4, and the respective grooves and hooks upon the jaws of the twister are in sucha position that the thread passes out of the mortise of the twister into such grooves and the parts of the thread are held by the hooks in the grooves of the jaws, and when the twister has been revolved haltl way the twister has been drawn back by the pin and inclined slot so that the ends of the twister are back from the holes Sand 9, and the threads are obliged to twist'together beyond the ends of the jaws as in Fig. 4, and as the twister completes its rotation it is roo -IIO

moved forward into the position -shown in` the'twisted loop, because the part of the twisted loop that is around the spring jaw is free to pass off from the spring jaw, and the other part of the twisted loop between the rigid jaw and the throat plate is only held with aslight friction and the thread pulls out from that position by the friction of the twisted loop around the eye-pointed needleas such eye-pointed needle rises; and it will be observed upon reference to Fig. 6, that the upper part of the lower side of the throat plate around the lower eye 9, is beveled to give ample room for the loop to east E from the spring jaw. The knot is completed as the threads are tightened as aforesaid.

By constructing the parts in the manner before described the operations are rendered perfect and reliable and the en-d movement of the twister is rendered as short as possible and the angle of the cam slot is such that the pin can be easily moved therein with but little friction. The ends of the jaws when closed being .cylindrical and filling the space between the upper and lower sides prevent the thread slipping out from the hooks 11 and 12, and the thread draws over the hooks as the jaws open and the loop is spread.

In some characters of sewing machines the cover plates over the shuttle raceway will come up at each side of the extending portion of the throat plate and also partially adjacent to the plate A', as illustrated at E F, Fig. 1.

I claim as my invention- 1. The combination with the throat plate,

with an opening for the passage of the eyefor the passage of the eye-pointed needle and` a longitudinal hole, of a rotatable twister within such hole having one rigid and one spring jaw, the exterior of the springjaw being rounding so as to be closed in its rotation by contact with the throat plate, the `jaws being recessed in their inner faces to form. an elongated eye and having grooves and hooks at the ends of the jaws for'twisting the thread, and means for giving an end movement to the twister as it is rotated, substantially as specified. j

3. The combination with the throat plate, of a twister formed of a cylindrical wire split longitudinally and having a spring jaw, hooks and grooves near the ends of the jaws, mechanism for giving an end movement of the twister as the same is rotated, a circular head upon the end of the twister with the upper edge removed to the level of the top of the throat plate, and a notch for receiving the inger nail for rotating such twister,substan tially as set forth.

4.. The combination with the throat plate having upper and lower sides, with openings for the passage of the eye-pointed needle, a diagonal slot and a longitudinal hole, of a rotatable twister within such hole having one rigid and one spring jaw, the exterior of the spring jaw being rounding so as to be closed in its rotation by contact with the throat plate, the jaws being recessed in their inner faces to form an elongated eye and having grooves and hooks at the ends of the jaws for i ALFRED W. COCHRAN.

Witnesses: j

GEO. T. PINCKNEY, A. M. OLIVER.

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