US399744A - dawson - Google Patents

Description

2 Sheets-Sheet i.

Patented Mar. 19; 1889.

Witnesses:

N. PETERS. PhnbLilhognpher. Washinglan. n. c.

.(No Model.) 2 Sheets'-Sheet 2. D. R. DAWSON.

OVEREDGE SEWING MACHINE. No. 399,744. Patented Mar. 19, 1889 Fig. 5-

W/f/VFSSES: m VENTOR,

N. PETERS; PhctoLilhomphur, Washlnfl'um D- Q rrn Starts ATENT rrrcn.

DAVID R. DAIVSON, OF DUNDEE, COUNTY OF FORFAR, SCOTLAND.

OVEREDGE SEWING=MACHINE.

SPECIFICATION forming part of Letters Patent No. 399,744, dated March 19, 1889.

Application filed August 21, 1888. Serial No. 283,347. (No model.)

of and in connection with the thread-barrel of sewing machines making an overedge stitch, and having the thread or yarn first laid round a barrel in loops, which are at lowed to pass off the end of the barrel in a manner to givea proper tension to the stitches as they are being successively tighten ed.

()veredge sewing-machines of the same general construction as that to which my in vention relates will be found shown and described in the British Patents Nos. 3393 of 1874, 2,856 of 1878, and 4,33% of 1885, and also in the United States Patent No. 294,627, dated March 4, 1884.

In over-edge sewing-machines of the kind referred to the needle, which is of a helical form or in the form of a circular arc, passes completely through the sacking or other ma terial which is being sewed, and also round the thread-barrel, laying a loop of the thread or yarn round the barrel at each circuit. In sewing a seam, during the first part of the operation, the thread is laid round the barrel without the stitches being tightened in the material; but when almost all the thread has been thus laid in loops on the barrel, the end of the thread being fixed in the material, which is being moved along either continuously or step by step, the loops successively pass oif the end of the barrel and the stitches become successively tightened in the material. The tension or tightness of the stitches depends upon the manner in which the loops pass off the end of the barrel, and it is this part of the sewing operation which the improved mechanism hereinafter particularly described is designed to effect in a better manner than heretofore.

On an accompanying sheet of explanatory drawings the improved parts are shown, together with a few other parts of the machine.

Figure 1 is a plan, Fig. 2 is a transverse vertical section, and Fig. 3 is a sectional front the barrel. Fig. 5 is a diagram, drawn to an enlarged scale, of a part of Fig. 1, and showin g the manner of sewing.

In the drawings the same reference-letters are used to mark the same or like parts wherever they are repeated.

In carrying out the invention according to one modification the end A of the barrel B is constructed of a stepped form-that is to say, with "hort portions 0 D of reduced diameters. The shoulders are rounded, and the successive smaller parts, 0 D, are, b preference, successively narrower or of less extent in the direction of the length of the barrel. Two such steps, 0 1), work satisfactorily, but there may be a single step or more than two. The stepped end A may be in the s me piece with the barrel B; or it may be, as shown, in a separate piece fixed to the barrel and e ther of metal or wood or other suitable material, preference being given to a material which does not become rapidly polished by the friction of the thread. A plate, E, fixed on the inner end of a rod or movable bracket, F, which is guided upon a fixed bar, G, is pressed against the barrel end A, and as each loop of thread or yarn approaches the end of the barrel it slips off the largest part onto the first step, C, and then onto the second step, D, and finally passes between the extreme end and the pressing-plate E. The thread or yarn has an action tending to move the barrel B back or toward the left hand, and its tension when tightening the stitches is in part due to this backward movement of the barrel, and in part to the resistance opposed to its slipping off the end of the barrel by the pressing-plate E. The barrel end A may be made entirely solid or without any movable part, and it acts satisfactorily if made so for some sizes of machine and kinds of sewing.

According to a second modification, however, and which is shown in the accompanyin g drawings, I combine What is hereinbefore described as the first modification with a button or small curved disk, H, fitted in the extreme end of the barrel end A, and pressed outward by a spring, J, which spring allows the button to yield inward when a loop passes between it and the pressing-plate E.

grooves in the socket in the barrel end A.

The pressing-plate E is by preference made, as shown, with its central part shaped to fit the front of the button H, and with a steplike depression round the middle part, such depression forming an annular groove which guides and controls the thread or yarn when entlering between the plate and the barrel en The general operation of the machine will be understood on reference to Fig. 5. The needle in rotating is continually carrying the thread through fresh stitch-holes in the cloth (marked 3 4 5 6) and at the same time throwing loops around the barrel B, which loops cannot be tightened until they slip off between the end D and the pressingplate E. The cloth is being moved to the right, and partly causesthe tightening by its dragging action. The loop is shown as just passing between the end D and the pressingplate E. The half of the neXt loop, which lies behind, from 1 to 2, is not indicated, in order to avoid confusion. The needle has a hook-notch near its tail, (not an eye,) and the thread is doubled and folded in, being caught in the hook. The barrel B rotates, and continually moves the loop toward the left, thus assisting in tightening the stitches. The barrel itself moves slowly to the left, but so to drop the loops off at its end somewhat faster than the rate at which the needle is forming fresh. loops, the difference corre sponding to the stitches tightened up from 4 to 1.

In combination with either the first or second modification there may be, and is by preference, fitted in connection with the pressing-plate E or bar F carrying it one or more ratchet'catches or equivalent devices to prevent the plate from being pressed outward or toward the right hand when the thread or yarn passes between it and the barrel end A. The pressing-plate E is moved toward the left hand by means of a cord, L, which passes round a pulley, M, and thence over a guidepulley, N, to a weight. (Not shown.) The pulley M is fixed on a spindle, having also fixed on it a fine-toothed ratchet-wheel, P, with which there engages a pawl, Q, centered on a fixed bracket. This ratchet-wheel with its pawl allows the weighted cord L to move the pressing-plate E toward the left hand, so as to follow the barrel A B and maintain against the end thereof a suitable pressure, which may be varied by altering the weight attached to the cord L, but prevents any return movement toward the right hand. \Vhen at the beginning of a fresh seam the barrel A B and pressing-plate E have to be moved toward the right hand, the pawl Q is turned out of gear, it being made with an upwardly-extending horn which the attendant worker can conveniently manipulate.

What I claim is- 1. The improved combination of parts, consisting of a thread-barrel made with astepped end and with a spring-pressed end button, a

pressing-plate shaped centrally to fit the front of the button andwith a step-like depression round the middle part, a movable brack et carrying the p ressing-plate and guided on afixed bar, a weighted cord actuating the pressing-plate, and a ratch et-and-pawl device connected to the pressing-plate, the several parts operating together, substantially as and for the purposes herein set forth.

2. The combination of the thread-barrel, having a stepped end, with the helical needle of an overedge sewing-machine, a pressingplate, and devices, substantially as described, to press the said plate up toward the stepped end of the thread-barrel, all substantially as set forth.

3. The combination of the helical needle of an overedge sewing-machine and athreadbarrel having a stepped end, and a springpressed end button, with a pressing-plate to bear against the said button, all substantially as set forth.

4. The combination of the helical needle of an overedge sewing-machine and a threadbarrel having a stepped end, and a springpressed end button, with a pressing-plate having a central step-like depression, as and for the purpose specified.

5. The combination of the helical needleof an overedge sewing-machine and a threadbarrel having a stepped end, with a pressingplate having a central step-like depression, as and for the purpose set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

D. R. DAlVSON.

VVitness'es:

EDMUND HUNT, DAVID FERGUSON.

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