US995312A - Tension mechanism for sewing-machines. - Google Patents

Description

F. s@ WOODHEAD.

TENSION MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JULY 14, 1910.

995,312. Patented June 13, 1911.

WITNESSES: INVENTOR j mi z od eaci ATTORNEY TNT 1Q FRANK S. WOODHEAD, 0F BRIDGEPORT, CONNECTICUT, ASSIGNOR TO THE SINGER MAN- UFACTURING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

TENSION MECHANISM FOR SEWING-MACHINES.

Specification of Letters Patent. Patented June 13, 1911.

Application filed July 14, 1910. Serial No. 571,879.

To all whom it may concern;

Be it known that I, FRANK S. WOODHEAD, a citizen of the United States, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Tension Mechanism for Sewing-Machines, of which the following is a specification, reference be ing had therein to the accompanying drawings.

This invention relates to improvements in thread-tension devices for sewing machines, especially that variety commonly termed thread-checks, and may be employed singly or in connection with some other form of tension device as in the present instance.

Prior to this invention it has been common to pass the needle thread across the flat surface of a permanently secured tension element and produce the desired tension by the employment of a coacting fiat spring or other yieldingly mounted element; but when the thread consists of closely twisted strands, as is commonly the case, the action of such tension elements is to twist the thread upon itself, which causes it to become entangled and form a knot or similar obstruction, the passage of which between said tension elements without causing the thread to break depends largely upon the strength of the thread and the degree of tension given it. To overcome this difliculty and facilitate the passage of such obstructions, the thread-ten sion elements are formed and mounted so that they are free to rotate, and the thread is passed across the tensioning surfaces thereof at one side of their diameter, which form of construction gives to said elements either a rotary or a non-rotary relationship with respect to the passing thread, dependent upon the condition of the latter.

In the accompanying drawings illustrating the invention, in the several figures of which like parts are similarly designated, Figure 1 is a view in perspective of the head and the front end portion of a sewing machine bracket arm, the latter being equipped with the improved mechanism together with a preferred form of coacting threadtensioning and thread-controlling mechanism, such as is commonly employed in connection with the improved mechanism when the latter is applied to machines operated by mechanical power at high speed. Fig. 2 is a View in 5 central section of the hollow tension stud,

together with full-line Views of the cylindrical thread-tension disks and thread-tension spring. Fig. 3 is a perspective view of the hollow thread-tension stud positioned so as to bring to view its integrally-formed thread-guide. Fig. 4 is a view similar to Fig. 3, showing the solid portion of the hollow tension stud uniting the main portion with that carrying the thread-guide.

1 represents the front end portion of the sewing machine bracket arm, 2 the head of said arm, 3 the preferred form of threadtensioning and thread-controlling mechanism used in connection with the present i11- vention, 4 the commonly employed needlecarrying bar and 5 the cloth-presser-carrying bar.

6 represents the hollow thread-tension stud adjustably secured by screw 7 in an opening 8 which is formed in the boss 9 carried by the arm 1, said stud being provided with a thread-guide 10 and thread-slot 11. The cylindrical thread- tension disks 12 and 13 are loosely mounted in the stud 6 with the end wall or thread-tensioning surface 14 of the disk 13 resiliently held by the thread-tension spring 15 against the thread-tensioning wall 16 of the. disk 12, the end 17 of said spring contacting with the bottom wall (not shown) of the opening 8.

The slot 11 passes through suflicient of the diameter of the stud 6 to permit the thread 18 to pass between the disks 12 and 13 at one side of their diameter, the thread being led through the eye 10 and in contact with the end wall 19 of the slot 11, as shown in Fig. 1. Under ordinary conditions, the thread will pass between the tensioning surfaces without producing any substantial movement of the tension disks, but when a knot or similar obstruction enters, its action on a point at one side of the diameter of said disks causes the latter to turn and in doing so relieves the thread of the excessive strain incident to the action of tension disks which are held against movement in substantially the same direction as the travel of the thread.

Claim:

In a tension device adapted to act on a running thread, the combination of a hollow thread-tension stud provided with a threadguide and a thread-slot, cylindrical threadtension disks loosely mounted in said stud and having their thread tensioning surfaces in alinernent With said thread-guide and In testimony whereof, I have signed my thread-guide slot, the line connecting the name to this specification, in the presence of thread-guiding portions of said thread-guide two subscribing Witnesses.

and thread-slotpassing at one side of the FRANK S. WVOODHEAD. 5 axis of said disks, and means for resiliently \Vitnesses:

holding said thread-tensioning surfaces in ABBIE D/I. DONIHEE,

abutting relationship. ALBERT M. WOLFE.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. G.

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