US1437786A - Pull-off means for sewing machines - Google Patents

Description

L. M. TUCKER AND P.W. HATFIELD. PULL-OFF MEANS'FOB SEWING MACHINES.

APPLICATION FILED OCT. 31, 1919.

1,437,786. Patented Dec. 0, 1922.

Patented Dec. 5, M22.

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LEWIS MARTIN TUCKER AND PERCY W. HATFIELD, OF WAKEFIELD,-IVIASSACHUSETTS,

ASSIGNORS TO WILLCOX 82: GIBBS SEWING MACHINE 00., OF NEW CORPORATION OF'NEW YORK.

YORK, n. Y., A

ruLL-orr iv nAns roe SEWING i/mcmnns.

Application filedoctober a1, 1919. Serial No. 334,727.

T 0 all whom it may concern:

Be it known that we, Lnwrs MARTIN TUoKnR and PERCY W. HATFIELD, citizens of the -United States of America, and residents of Wakefield, Massachusetts, have invented new and usefullmprovements in Pull-OE Means for Sewing Machines, which .ber 15, 1912, the pull-ofi? means of thisinvention are not restricted to use with any particular type or make of'sewing machine.

In forming a so-called interior seam, such asthose on the sides of ladies underwear begun at a point relatively distant from the edge of the material, it is important that the formation of perfect stitches should begin with the very first stroke of the needles, because missed or imperfect stitches, even at the start of such a seam, result in marred appearance and defective work. In" forming such interior seams with the aforesaid fiatlock machine, someoperatives have experienced missed or malformed stitches at the beginning of the seam. The probable cause is that in starting or preparing to start the seam, the somewhat lengthy threadends ordinarily left at the finish of a preceding operation are gotten into such. posi; tion as to be severed by the. blades of the trimmer mechanism, thus leaving only short lengths of the needle-threads beyond the eyes of the needles inadequate to enable the pressure of the presser-foot to grip and anchor said thread-ends against the backpull imposed thereon as the needles descend to pull more needle-thread through the tensions and form needle-thread loops through the work to be entered by the loo-pers. Such failure to hold the needle-thread ends, and the consequent failure to form needle-thread loops for the looper-threads, result in one or more missed or imperfect stitches before the formation of perfect stitches begins The principal object of this invention is the provision of automatically operating pulled means which will overcome the vof the mechanism shown inFig. 1; and

aforesaid diiiiculties by forming slack in the needle-threads between the tension means and the eyes of the needles suflicient to ac commodate the down-stroke of the needles in beginning a seam without imposing backpull sufficient to draw the relativelyshort needle-thread ends down through the work. The aforesaid and other objects vand advanta ge's attained by the invention'will be more fully understood from the following detailed explanation with reference to the accompanying drawing illustrating what is now believed to be the preferred embodiment of the invention as applied to a machine of the character of the aforesaid flatlock machine. I Insaid drawing- I 'Fig. 1 is a plan view of a portion of a sewing machine with the pull-ofltmeans of I this invention applied thereto;

"Fig. 2 is a perspective view of a group Fig. 3 is a perspective view of some of the parts. i I

The drawing will first be explained in so far as it illustrates structure of the aforesaid commercial flatlock machine, such structure (except for minor differences) corresponding to that illustrated in the aforesaid Merritt Patent No. 1,041,652, and particularly in Figs. 49, 50 and 51 thereof.

5 is a portion of the hollow bridge and 6 a portion of the hollowleft-hand standard of the machine-frame. up for the four needle-threads a, b, c, d, and 8 a rotary take-up for the four looperthreads 6, f, 9 audit. 9 is the looper-thread tension-stand, secured to the top of the bridge 5 and having mounted thereon a. thread-guide-plate 10 through converging passages of which the looper-threads pass to "four sets of tension plates '11, from which letter said. threads pass through guide hooks 12 and thenceover rotary take-up 8. A bar 13, sliding freely in passage through the base of stand '9. has secured thereon an upwardly extending arm 14 which in turn is secured to the end of a rod 15 (parallel to bar 13) which also slides freelyin a bearing in the stand 9. Rod 15 passes through all of the tension-plates 11 and isencircled by a spring 16, the tension of which, in pressing the tension-plates together, is adjust- 7 is a rotary take- I able by turning nut 17 screw-threaded onto 20 is the needle-thread tension-stand secured to the top of bridge 5 at the left-hand end thereof and having mounted thereon a thread-guide-plate 21 through converging passages of which the four needle-threads pass to four sets of tension-plates 22 and thence through guide-hooks 23 and over rotary take-up 7. Bar 13 also slides freely in an opening through the base of stand 20. An arm 24 secured to bar 13 is fixed to the ends of rods 25 and 26 which slide freely in bearing openings in stand 20. Rod 25 passes through the tension-plates 22 and is encircled by a spring 27, the tension of which, in pressing the plates together, is adjustable by a nut' 28 on the end of rod 25. Rod 26 is encircled by a spring 29, passes through tension-disks 30 and has on its end a nut 31 for adjusting the tension of said spring in pressing said disks together. The tensiondisks 30 and a thread-guide 32 are for a cross-thread, not shown. A spring 33 encircling the end of bar 13 bears at one end against arm 24 and at its other end in a socket (dotted lines Fig. 1) in the end-of stand 20, and is of sufiicient tension to normally force the bar 13 and all of its connections to the left until the stop-pin 34 through bar 13 abuts the end of the base of stand 20 (see Fig. 2 and dotted lines Fig. 1), such being the normal position of the parts when the thread-tensioning means are exerting tension uponv the threads. As shown in Fig. 1, the upright plate forming part of the thread-stand 20, at its left-hand end, fits over an opening 35 in the upright wall in the hollow standard 6 of the machine-frame, with the end of bar 13 projecting into the interior of saidhollow standard where it can be engaged by the beveled or cammed upper end of: an arm 36 secured to a rock-shaft 37. When the presser-foot (not shown) is lifted, the shaft 37 is rocked, by connections such as shown in Fig. 4 of the aforesaid Merritt patent, moving arm 36 from the position shown in dotted lines to that shown in full lines in Fig. 1, thereby moving bar 13 (and all of its connections) to the right against the tension of spring 33 and releasing all of the thread-tensioning means;

Coming now to an explanation of the pulloff means of the present invention, a plate 40 has an opening 41 through which bar 13 passes. To provide for securing said plate on the bar in any desired position of adjust ment lengthwise of the bar, a slot 42 is formed to intersect opening 41, thereby providing two opposing members, which may be drawn together by a screw 43 to contract the open.- ing 41 about the bar 13 and thereby clamp the plate in. anydesired position on the bar. A bell-crank lever 44. is pivoted to plate 40 by a screw-stud 45.. A link 46 is pivotally connected to an arm ofle'ver' 44. by a screwstud 47, said Iink'at' its other end. .heing 1 ,aevnee pivotally anchored to a screw-stud 48, which may be one of three screws employed in securing, the tension-stand 9 in place. Screwstud 47 may engage any one of the threaded openings 51 of lever 44 to vary or adjust the movement imparted to said lever. The other arm of lever 44 has an upturned end provided with an opening to receive a thread-engaging member 49 and with a set-screw 50 to secure said'member in any desired. position of adjustment. Member 49 is preferably made of stifl wire bent in the peculiar way illustrated to form an elongated slot 52 through which the four needle-threads pass after they leave the tension-plates 22 and before they engage the hooks 23.

In operation, when the arm 36 is in the dotted line position, Fig. 1, clear of the end of bar 13 (a position to which said bar is automatically moved by lowering of the presser-foot, as shown by the aforesaid Merritt patent), spring 33 moves bar 13 to the left until arrested by stop-pin 34. and through the rods connected to bar 13 throws all of the tension means into action to impose tension upon the threads, and brings the thread pull-off means to the position shown in dottedlines in Fig. 1. When the sewing machine presser-foot is lifted at the end of a seaming operation, arm 36 is thereby moved to its full-line position Fig. 1, moving bar 13 and its connections to the right against the pressure of spring 33 and releasing all of the thread-tensioning means. In such movement, bar13 also moves the pull-off means to the position shown in full lines, Fig. 1, such movement including swinging of lever 44 about its pivot-stud 45, whereby thread-engaging member 49 pulls the four, needle-threads out to. the position shown in full lines, Fig. 1. WVhen, at the beginning of another seaming operations the presser-foot is lowered, the arm 36 thereby shifted to its dotted line position, the rod 13 actuated by spring 33 to again bring the thread-tension means into action, and the thread pull-off means moved to the dotted line position thereof, Fig. 1,--such movement of the thread pull-off member 49 slacks the needle-threads to the amount of thread pulled past the tension-plates 22 by the previous movement of member 49 to its full line position of Fig. 1. When the needles make their first downward move ment, say in beginning an interior seam such. as hereinbefore mentioned, and with only short thread-ends through the needlee'yes and in. the grip of the resser-foot, the aforesaid slack in the needle-threads is sufficient to accommodate the full movement of the needles, thereby relieving the needlethreads of back-pull (such as would be incident to pulling more thread past the tension means) suficient tov draw the ends thereof dewnwardthrough the workand result in missed or malformed stitches at the beginning of the seam.

The invention may be used for one or more threads and is not limited to embodiment in the particular form illustrated and described, as other embodiments may be made without departing from the spirit and principle thereof.

What is claimed is 1. In a sewing machine, the combination wit-h a longitudinally movable part thereof to which movement is imparted upon raising and lowering of the presser-foot to engage work thereunder, of pull-ofi? means operable upon one or more stitch-forming threads and attached to and actuated by longitudinal movement of said first-named part.

2. In a sewing machine, the combination with needle-thread tensioning means and a movable part to which longitudinal movement is imparted upon raising and lowering of the presser-foot to engage work thereunder, of pull-off means attached to and actuated by longitudinal movement of said part to draw needle thread past the tensioning means and provide slack therein available to the needle or needles in subsequent operation thereof.

In a sewing machine, the combination with needle-thread tensioning means and a. movable part of the machine to which 1ongitudinal movement is imparted upon raising and lowering of the presser-foot to engage work thereunder, of a pull-off member pivotally attached to and actuated by longitudinal movement of said machine part to make pivotal movement and thereby draw needle thread past the tensioning means and provide slack in the thread available to the needle or needles in subsequent operation thereof.

In testimony whereof we have signed this specification.

L. MARTIN TUCKER. PERCY W. HATFIELD.

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