US2462812A - Thread-tension device for sewing machines - Google Patents

Description

` Feb. 22, 1949. F. PARRY ET AI.

THREAD-TENSION DEVICE FOR SEWING MACHINES 2 sheeft-sneet 1 Filed Feb. 9, 1946 Feb. 22, 1949` F, PARRY ET AL 2,462,812

THREAD-TENSION DEVICEA FOR SEWING MAHINES Filed Feb. 9, 1946 2 Sheets-Sheet 2 Patented Feb. 22, 1949 UNITED Srl'lf'AfI'ELS THREAD-TEN SION DEVICE FOR SEWING MACHINES Frank Barry and Berthold P. Pinkvoss, Bridgeport, Conn., assignors to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New. Jersey Application February 9, 1946, Serial No. 646,603

10 Claims.

This invention relates to thread-tension devices for sewing machines and, more particularly, to thread-tension devices of the two-disk releasable type for tensioning the needle-thread.

Devices of the present type heretofore used were providedy with an abutment-plate formed with a rotation-restraining nger which was adapted to enter an aperture formed in the sewing machine wall. With this type of construction there was a tendency for the abutmentplate to cant whenever the'tension-spring pressure was released therefrom, and thus the rotation-restraining finger sometimes became wedged against the apertured side wall of the machine frame when the spring pressure was again applied to the abutment-plate. With the abutmentplate thus held out of its proper position, the tension unit became inoperative.

The principal object of the-present invention is to` provide a. thread-tension unit which will overcome the above noted difficulty.

Another object of the present invention is to provide a needle-thread tension unit with means to prevent inadvertent unthreading of the checkspring.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations, and arrangements of parts hereinafter set forth and illustrated in; the accompanying drawings of a preferred embodiment of the invention, from whichl the' several` features of the invention and theV advantages-'atltained thereby will be readily understood by those skilled in the art.

Fig. 1 represents a face view of the needle-bar head of a sewing. machine carryingV a pair of tension devices embodying one form of theinvention'.

Fig. 2 represents a rearfelevation view of the needle-bar head carrying the twotensionunits.

Fig. 3 representsan enlarged side View of one form of the tension device.

Fig. 4 represents a longitudinal sectional view of the unit shown in Fig. 3V.

Fig. 5 represents an enlarged view of a second form of tension device.

Fig. 6 represents a disassembled perspective view of the tension device shown in Fig..3.

Fig. 7 represents aV disassembled perspective view of elements forming a part of that device shown in Fig. 5.

Fig; 8 represents a sectional View taken substantially along line 8--8 of Fig. 4;

Fig. 9V represents a sectional View taken substantially. along line Q-S'of Fig. 5.

Fig. 10 represents a longitudinal sectional' view of. the` unit shown inv Fig. 3, but with the tension: disks intheir. separateclv or open position.

Thesewing machine, illustrated:Y in the` draw.'- ings., has` a. frame including a work-supporting bed-plate indicated by line i9 and a hollow bracket-arm head il. Journaled for vertical reciprocation in the bracket-arm head Il is a needle-bar l2 carrying at its lower end a pairv of needles of which only one, designated by the numeral E3, is shown, said needle-bar l2 lbeing endwise reciprccated vertically by any usual or suitable actuating connections with a horizontally disposed rotary actuating shaft Mi. Cooperating with the needles I3 in the formation of lockstitches, are rotary loop-takers (not shown) which may be of any suitable construction.

Mounted on the head Il are the usual rotary take-up disks l5 and l carrying the take-up elements I? and E8, respectively, as well as the thread-confining rings I'S and 253.

Each of two needle threads 2 l, drawn from its supply (not shown), is threaded through a tube 22 mounted upon the bracket-arm head i l. From the lower ends of the tubes 22, the threads 2l are each led about one of the two tension devices designated generally as 23, from whence the threads are directed upwardly to be disposed between the take-up disk I and its associated thread-confining ring 2Q tol overlie the threadengaging elements i8. From the elements it, the threads pass forwardly between a face-plate 24 and the machine-head ll, over the threadengaging elements li between the disk l5 and its associated ring i9. From the elements il, the threads `pass downwardly successively through the face-plate thread-guides 25 and 26 to be directed to the proper needle.

Further explanation of the present rotary take-up is not deemed necessary and, for a cornplete disclosure of the same, reference may be had to the U. S. patent of S. Zonis, No. 2,385,960, Oct. 2, 1945.

Referring more particularly to the present invention, each of the tension devices 23 comprises a cup-shaped support or sleeve member 2 which is seated within one of. two apertures 28 formed. in the head E i. A set-screw 29, threaded into the head, engages an annular groove 30 in the sleeve member 21 for the purpose of securing the latter element within the aperture 2B. In the rear portion of the sleeve 2l is formed an aper ture 3ll for entrance by the reduced rear end` portion 32 of a threaded stud or arbor member 33 which is secured within the aperture 3l by means of a set screw 34.

Slidably mounted upon an intermediate portion of the arbor 33 is an apertured abutmentf plate 35 provided with two ears 38. which are bent about a ycircumferential ila-nge 3l formed on thesleeve 2l. the flange 3l at diametrically oppositev sides,

thereof and` functionI as guides which. permit the`V abutment-plate to turn; about the. arbor 33' but These ears: 33 preferably engage:

which prevent; the `plate from canting on the arbor.

Extending rearwardly from the peripheral p01'- tion of the abutment-plate is a motion-restraining nger 38 which is adapted to enter one oi the two apertures 39 formed within the face portion of the head H.

Extending forwardly from the peripheral portion of the abutment-plate 35 is a thread-guiding finger 46, the function of which will be hereinafter described. Also extending forwardly from the peripheral portion of the plate is a thread-confining nger 4l which forms, in conjunction with the plate proper, a thread-conning notch or thread guide 42.

Abutting against the outboard face of the abutu ment-plate is an inner disk 43 of a pair of spring biased and centrally apertured thread-tension disks mounted upon the arbor 33, the outer disk being designated by the number 44. Also mounted upon the arbor 33 is an anchor-disk l5 having a diameter-bar 4S passing through a slot si formed in the outer end of the arbor 33. lThe outer endportion of the arbor 33 is also provided with threads 48 for a tension-adjusting thumb-nut lil for the purpose of forcing a bee-hive spring d against the anchor-disk 45 which transmits the pressure of the spring directly against the disks 43 and 4,4. By adjusting the thumb-nut 49 along the threaded portion of the arbor, the pressure existing between the disks 43 and it may be varied.

An endwise movable tension-release pin 5i is supported in a longitudinal bore 52 of the arbor 33. The forward end of this pin 5E is adapted to engage the diameter-bar 46 of the disk 45 and rear end thereof is adapted to be engaged by a cam-lever 53 which is actuated by the usual presser-foot lifting lever 54. This tension-release pin 5I operates in the usual manner in that it is adapted to be pushed by the cam-lever in a direction to relieve the tension- disks 43 and 44 of the pressure of the tension-spring 56. Fig. 1Q illustrates the positions assumed by the disks when relieved of the spring pressure.

Referring to Fig. 4, the sleeve 21 has a cylindrical aperture 55 in which is disposed an enlarged portion 56 of the arbor member 33 having a slot 51 formed longitudinally thereof. Coiled about this enlarged portion 56 is the usual torsion check-- spring 58, one end 56 of which is anchored in the slot 51. The other end of the torsion check-spring is extended outwardly at 6) through a segmental clearance opening Z1 formed in the outer end of the sleeve 21. At its free end, the outwardly extending arm 60 of the spring is bent backwardly to form a thread-engaging loop 6l. The arm 6e of the check-spring is limited in its movement in one direction by a stop-ledge 62 forming one wall of the segmental opening 21 of the sleeve 21. Circular adjustment of the sleeve 21, within the machine aperture 28, determines the stopped position of the looped end 6| of the check-spring. lThe tension of the check-spring may be adjusted by loosening the set-screw 34 and turning the arbor 33 in its socket in the supporting sleeve 2l and by subsequently tightening the screw 34.

Referring to Fig. 6, the flange 31 of the sleeve 21 is provided with a notch 63 for the purpose of facilitating placement of the abutment-plate 35 in its proper position relative to the sleeve. Thus, when assembling the sleeve and abutment-plate together, one of the ears 36 of the latter unit may enter the notch 63, thereby permitting the ears 36 to be bent prior to the assembly operation.

4 Referring to Fig. 1, the tension unit is disclosed in its operable condition. The thread 2l passes over the thread-guiding finger 46, then about the arbor 33 between the disks 43 and 44, and then is directed through the thread-confining notch 42 from which it passes under and about the checkspring before being directed to the take-up elements. By thus passing the thread about the thread-guiding finger it before passing the same between the disks, the thread is prevented from fouling the check-spring.

From the above description, it is to be understood that the present abutment-plate 35, with its guiding ears and motion-restraining finger, is not only restrained from turning about the sleeve 21 but, at the same time, -it has no tendency to cant.

Considered circumferentially of the guard-plate the stop-nger 33 thereof is located between the thread-guiding nger 4t and the thread-conning notch 42; the latter being located between the stop-ledge S2 of the sleeve 21 and the stopfinger 3. As the arm 66 of the check-spring is confined to vibratory movement between the stopledge 32 and the stop-finger 38, the check-spring Ycannot foul the portion of the thread directed from the tube 22 to the tension device by the thread-guiding finger dil which is disposed at the side of the stop-nger 38 opposite to the checkspring side thereof.

Figs. 5, 7 and 9 disclose a modified form of the present tension unit. This modified unit is exactly the same as the above described unit but for an addition of a check-spring guard element.

Referring to Figs. 5 and 7, a check-spring guard element 64,V having a generally dished shape, is inserted between the outer disk 44 and the anchor-disk 45. Projecting upwardly from the periphery of this dished element are a pair of ears 65 which, when the element is assembled, embrace the thread-guiding nger 46, thus to prevent rotation of the element. Also provided in the periphery of this element is a slot 66 through which extends the free end portion 61 of the check-spring 58. Referring to Fig. 9 it is to be seen that by so inserting the portion 61 of the check-spring within the slot 66, the possibility of the thread 2l disengaging itself from the check-spring loop 60 becomes rather remote. Therefore, the present guard 64 is particularly useful whenever an eX-cess of slack occurs in the thread 2l, as this element will prevent inadvertent unthreading of the check-spring.

Having thus set forth the nature of the invention, what we claim herein is:

1. In a thread tensioning device for sewing machines, a support formed with a flange, an arbor carried by said support, spring-pressed opposed tension-disks mounted upon said arbor, a thread-guide carrying abutment-plate disposed adjacent one of said tension-disks, and interlocking means between the flange of the support and the abutment-plate providing for relative turning adjustment of said support and abutment-plate and for confining said abutment-plate against sidewise movement.

2. In a thread tensioning device for sewing machines, a cylindrical supporting member having a circumferential flange, an arbor carried by said supporting member, releasable thread tensioning means mounted upon said arbor, a thread-guide carrying abutment-plate disposed adjacent said thread tensioning means,'and ears extending from said abutment-plate and bent about said ange of the supporting member.

3. In a thread tensioning device for sewing'- machines, a supporting member having a stopshoulder, an arbor carried by and projecting from said supporting member, releasable thread tensioning means carried by said arbor, a threadguide carrying abutment-plate disposed between said tensioning means and said supporting member, a check-spring having a thread-controlling arm yieldingly engaging said stop-shoulder, and abutment-plate confining means comprising interlocking members between said support and said abutment plate which provide for relative turning adjustment of said supporting member and abutment-plate about the longitudinal axis of said arbor and for restraining said abutmentplate against sidewise movement upon release of said thread tensioning means.

4. A sewing machine tension device having an arbor, thread tensioning means mounted on said arbor, a thread-controlling check-spring having one end thereof anchored to said arbor and having a thread-engaging free-end portion, an abutment-plate disposed at one side of said tensioning means and provided with a thread-guide in the region of the thread-engaging portion of said check-spring, a guard-plate mounted upon said arbor at the opposite side of said tensioning means in position to house the free end of said check-spring, and interengaging means carried by said abutment-plate and guard-plate for preventing relative turning movement thereof about said arbor.

5. A sewing machine tension device having an arbor, thread tensioning means mounted on said arbor, a thread-controlling check-spring anchored to said arbor at one side oi said tensioning means, said check-spring having a free end thread-engaging portion bent about and extending to the opposite side of said tensioning means, means housing the free end of said check-spring and consisting of a anged guard-plate mounted upon said arbor for movement endwise thereof, and means comprising a stationary finger eX- tending across said tensioning means for restraining said guard-plate from turning about said arbor.

6. A sewing machine tension device having an arbor, thread tensioning means mounted on said arbor, a thread-controlling check-spring having a thread-engaging free end portion, an abutmentplate at one side of said tensioning means and provided with a thread-guide for directing the thread from said tensioning means to said checkspring, means housing the free end of said checkspring and comprising a guard-plate mounted on said arbor at the side of said tensioning means remote from said abutment-plate, and a nger connecting and providing for relative movement of said abutment-plate and guard-plate.

7. In a thread tensioning device for sewing machines, an arbor, thread tensioning means carried by said arbor, a thread-controlling checkspring having one end anchored to said arbor and having a yielding thread-engaging portion, a stationary abutment-plate provided with laterally extending stop means limiting movement of the thread-engaging portion of the checkspring responsively to the pull of the thread thereupon, a laterally extending lead-in threadguide carried by said abutment-plate at one side of said check-spring stop means, and a laterally extending lead-out thread-guide carried by said abutment-plate at the other side of said checkspring stop means.

8. In a thread tensioning device for sewing machines, an arbor, thread tensioning means carried by said arbor, a thread-controlling checkspring having a yielding thread-engaging portion, and an abutment plate disposed adjacent said thread tensioning means, said abutment plate having a stop-finger projecting laterally from one side of said plate and disposed to be engaged by said check-spring, and a pair of thread-guides projecting from the other side of said abutmentplate and spaced on opposite sides of said stopfinger.

9. In a thread tensioning device for sewing machines, an arbor, thread tensioning means carried by said arbor, a thread-controlling checkspring having one end anchored to said arbor at one side of said thread tensioning means and having a free end thread-engaging portion bent about and extending to the opposite side of said thread tensioning means, and means for housing the free end of said check-spring, said means including a guard-plate formed with a laterally extending flange slotted to provide an opening through which the free end of the check-spring extends, and means for restraining said guardplate against turning about said arbor.

10. A releaseable tension device for sewing machines, comprising, a supporting sleeve having at one end thereof a clearance opening and a circumferential flange, an arbor mounted in said sleeve for turning adjustment and extending through the anged end of said sleeve, a pair of opposed tension-disks mounted upon said arbor for movement endwise thereof, a check-spring embracing said arbor within said sleeve, said check-spring being anchored to said arbor and having a reversely bent free end portion extending through said clearance opening of the supporting sleeve and about the peripheries of said tension-disks, thereby to provide a yieldable thread-engaging loop, an abutment-plate mounted upon said arbor between said tension-disks and the flanged end of said sleeve, said abutmentplate having a primary stop-finger overhanging said sleeve and an oppositely directed secondary stop-finger overhanging said tension-disks, means for preventing canting of said abutmentplate comprising abutment-plate ears embracing said flange, a thread-confining nger extending from said abutment plate toward and having its free end spaced from said secondary stop-iinger, a guard-plate mounted upon said arbor at the side of said tension-disks opposite to said abutment-plate, said guard-plate having a slotted flange entered by and housing the free end of said check-spring, and said guard-plate having a peripheral stop-notch entered by said secondary stop-finger, and spring means for yieldingly pressing said tension-disks towards each others.

FRANK PARRY. BERTHOLD P. PINKVOSS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 994,509 Gray June 6, 1911 1,862,658 Chason June 14, 1932 2,131,005 Chason Sept. 20, 1938

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