US290345A - Edwaed murphy - Google Patents

Description

('No Model.)

' -E. MURPHY.

AUTOMATIC TENSION DEVICE FOR SEWING MACHINES.

lPatented Dec. 18, 1883 N. PETERS. PhoM-Lflhogmphu. washin gen. 0 Q

' UNRTED STATES PATENT, @rrrcn.

EDWARD MURPHY, OF NEW YORK, N. Y., ASSIGNOR TO THE KRU S E 8t MURPHY MANUFACTURING COMPANY, OF SAME PLACE.

AUTOMATIC TENSION DEVICE FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 290,345, dated December 18, 1883.

v Application filed August 30, 1883. (N0 model.) I

To all whom it may concern..-

Be-it known that I, EDWARD MURPHY, of the city, county, and State of New York, have invented a new and useful Improvement in Automatic Tension Devices for Sewing-Machines; and I do hereby declare that the following is a full and eXact description thereof, reference being had to the accompanying drawings, and to the, letters of reference marked thereon, making a part of this specification.

My invention relates to that class of tension devices for sewing machines in which the thread is firmly held until the loop or stitch is nearly or wholly drawn up tothe material, and is then wholly released or held less firmly during the remaining movements of the needie, by means of which a proper tension is obtained automatically, whatever may be the size of thread, length of stitch, or thickness and nature of the material to be sewed, without requiring a separate adjustment for its adaptation to the constantly varying requirements of the work. Ingenious devices adapted to effect this object have been heretofore employed; but where effective they have involved a multiplicity of parts, expensive in construction and more or less cumbersome.

The object of my invention is to provide a neat, sensitive, positive, and quickly operative device, including the fewest possible elements, and which may be compactly arranged and concealed upon the frame and operated directly by the oscillations of the needle-arm.

It consists in employing a curved springplate firmly secured at one end to the under side of the arm of the frame, and which extends to and is operated at its other end by a cam or shoulder oscillating with the needle arm, for the purpose of actuating one of two bearing-disks placedupon thetop of the frame, and betweenwhich the thread is passed, asmore particularly pointed out in the claims, whereby said disk is pressed closely upon the other by the tension of the spring when it is actuated by the cam on the needle-arm, but is otherwise left free to press loosely thereon and allow the thread to pass freely between the disks, the cam being so arranged and adjusted relatively to the needle-arm as that the spring plate and tension will not be influenced thereby, ex-

cept at the time when in the movements of the needle the loop is being drawn up to the cloth.

In the accompanying drawings, Figure 1 is a view in elevation of a sewing-machine with my improvement attached, showing the needle in its descent and the tension-spring about to be acted uponto hold the thread, a portion of the needle-arm being broken away to show the cam which operates the tension-spring. Fig. 2 is a plan view of a part of the frame of the machine and needle-arm, the course of the thread from the spool around the tension device being illustrated in dotted lines; Fig. 3, atransverse sectional View in the line 3 y of Fig. 1, showing the tensionspring and its connection with the needle -bar frame, needle arm, and tensiondisks; Fig. 4, a detached front elevation of the face-plate, needle-bar, and pressure-foot bar,

illustrating the form and location of the takeup device used in combination with my automatic tension.

Myinvcntion is applicable to all sewing-machines in which the needle is operated by the action of an oscillating or vibrating arm.

A represents the needle-arm of a sewing-machine, C, a pivot secured to and projecting from the fixed arm B of the frame, and upon which the needle-arm is made to oscillate by means of a link, D, connecting with an eccentrio on the main shaft E. R represents the spool support or carrier projecting from the arm B at its rear end, T, Fig. 4, the spring take-up, by which the slack of thread is taken up as the needle rises.

The tension device consists simply of two separate superimposed rings or annular disks, F G, (see Fig. 3,) of which the lower one is fitted loosely in an encircling-recess formed in a boss, H, on the upper side of the arm'B of the frame, preferably about midway its length. A rod, J, passes loosely through the central aperture in the two disks and through an aperture pierced centrally through the boss and the arm. The upper end of'the arm is threaded to engage a cap-plate, L, which fits over the upper disk, F, and an outer lock-nut, M, which screws down upon said cap-plate. lower end of the rod is secured to a curved spring-plate, N, made fast at one end by a screw or other device to the under side of the The IOO

arm B of the frame, at a point preferably about midway between the tension-rod J and the needle-bar, and which is extended thence under the arm B to a point in line with the pivotal axis of the needle-arm A, where it is made to bear with its elastic tension against a cam-disk or ring, I, secured by means of a set-screw firmly on theinner side of the needlearm to its pivot-pin C, so as to oscillate therewith, or, if the pivot-pin be fixed, then to the needle-arm itself, to vibrate therewith upon said pin. The cam P is formed with two surfaces of different radii, each concentric with its axis, and which are connected by a sudden incline, and the end of the spring is made to bear against said surfaces, so as to be forced out by the one and allowed to drop inward by the other. e

The adjustment of the tension-rod J to the disks F G and the spring N is so determined as that, when the spring is forced out by the larger portion of the cam, the rod will be drawn down thereby with sufficient pressure to draw down and bind the upper disk, F, firmlyupon the lower disk, G; but when by the oscillation of the cam the spring is left free the tension upon the rod J is removed, and the rod is slightly lifted by the elasticity of the spring, leaving the disks loose, and the upper one bearing upon the interposed thread with simply the pressure due to its weight. The cam P is so adjusted with reference to the needle-arm as that the oscillating movements of the arm shall operate to force and bear out the spring N while the needle is completing its downward movementand making its upward movement, and until the loop is almost or quite drawn up to the cloth, and then to suddenly release it so soon as during the upward movement this is accomplished. The thread is preferably passed, in the direction shown by dotted lines in Fig. 2, from the spool upon the spool-support R forward around the rod J, between the disks F G, thence back through the guide-wire S, secured to the spool support R, and again forward through the eye S upon the needle-arm, the guide-wires S upon the upper end of the face-plate, and 8 upon the upper end of the needle-bar. through the take-up T, and finally to and through the eye of the needle. The thread may be conducted from the spool through the tension device and to the needle in any other suitable manner without departing from my invention, and the tension spring and disks may obviously be secured to the oscillating needle-arm in a manner similar to that of its attachment to the arm B of the frame, as shown in the drawings; but such a modification necessitates the use of a fixed cam si'cured to the arm B at the pivotal point of the needle-arm, in stead of to the needle-arm itself, to vibrate therewith.

The operation of this simple automatic tension is as follows: After being led from the spool to the needle in manner as above described, and as shown by dotted lines in Fig. 2, the thread will, during the operation of forming the stitch, be firmly held between the disks F G by the tension of the rod J upon the disk l produced by the outward throw of the spring-plate N by the pressure thereon of the enlarged portion of the cam P. So soon, however, as the stitch is completed and the loop properly drawn up, the oscillation of the needle-arm having the cam will carry its reduced portion by the end of the spring, and thus release it suddenly, and its resiliency will cause it not only to release the rod J from the tension, but lift it slightly, so that the only friction now exerted upon the thread in passing between the disks will be the weight of the upper disk, which is sufficiont to prevent an excess of thread being drawn off of the spool.

I do not claim, broadly, an automatic tension in a sewing-machine comprising a springplate actuated by a cam moving in unison with the stitch-forming devices to produce an intermittent pressure upon the thread in the machine. My improvement relates especially to the combination of devices herein described, by means whereof an automatic tension is simply and effectively produced in machines constructed with an oscillating needle-bar.

I claim as my invention The combination, with annular tensiondisks F G, superimposed upon the fixed arm B of a sewing-machine frame, and with a central rod, J, attached to a cap-plate resting upon said disks and passing loosely through the disks and arm, of an elastic plate, N, fitted beneath said fixed arm, and which, being secured thereto at a point between the rod J and the needle-bar, engages the rod, and extends thence under the arm B to the pivot of the oscillating needle-arm A, to bear against and be actuated by a cam upon the inner side of said arm, substantially in the manner and for the purpose herein set forth.

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

EDlVARD MURPHY. lVitnesses:

A. WV. STEIGER, J. F. ACKER, Jr.

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