US2902959A

US2902959A - Thread tension mechanisms for sewing machines

Info

Publication number: US2902959A
Application number: US694682A
Authority: US
Inventors: Hacklander Hans
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1956-09-14
Filing date: 1957-11-05
Publication date: 1959-09-08
Anticipated expiration: 1976-09-08
Also published as: GB839233A

Description

it. 12u15 H. HACKLANDER 2,902,959

THREAD TENSION MECHANISMS FOR SEWING MACHINES 5 Sheets-Sheet 1 Sept. 8, 1959 Original Filed Sept. 14, 1956 I N VEN TOR. Hans Hack/ander ATTORNEY Sept 8, 1959 H. HACKLANDER 2,902,959

THREAD TENSION MECHANISMS FOR SEWING MACHINES original Filed sept. 14, 195e s sheets-sheet 2 ma f` -l i '0G-fnv y 28a g i Q ...E cr; N w" N @N srv-'mr w n .N

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Hans Hack/ander ATTORNEY Sept. 8, 1959 H. HAcKLANDI-:R 2,902,959

' THREAD TENSION NEcHANIsNs FOR sEwING MACHINES original Filed sept. V14, 195e s sheets-sheet s IN VEN TOR. Hans Hack/ander www ATTORNEY United States Patent Office Patented Sept. 8,v 1959 THREAD TENSIN MECHANISMS FOR SEWING MACHINES Hans Hacklander, Warren Township, NJ., assignor to The Singer Manufacturing Company, Elizabeth, NJ., a corporation of New Jersey Original application September 14, 1956, Serial No. 609,836. Divided and this application November 5, 1957, Serial No. 694,682

4 Claims. (Cl. 112-238) The present invention relates to sewing machines and more particularly to a thread tension mechanism for sewing machines.

It is an objec-t of this` invention to provide an improved thread' tension mechanism having a pair of opposed thread tension discs that are released by means of a releasing pin projected between the idiscs. It is a further object ofk this invention to provide a tension releasingv mechanism combined with the. presser lifter mechanism that is so constructed and arranged as to effect complete release of the tension mechanism during the initial actuation of the presser lifter mechanism.

Having inv mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangement of parts as illustrated in the, presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function,` operation, construction and advantages of ity when ready in conjunction with the accompanying drawings in which:

Fig. l is a fragmentary vertical sectional view longitudinally of the bracket arm of a sewing machine embodying the present invention Fig. 2 is a horizontal sectional View through the bracket arm of the sewing machine illustrated 4in Fig. 1

Fig. 3 is a fragmentary elevational View of the needle thread tension device of the sewing machine illustrated in Fig. l.

Fig. 4 is a view similar to Fig. 3 but illustrating the parts in a different position. Fig. 5 is a sectional view taken substantially on the line 5-5 of Fig. 4.

The present invention is herein illustrated and described as embodied in the sewing machine forming the subject matter of my prior application Serial No. 609,836, filed September 14, 1956, from which the present application has been divided.

With reference to the drawings there is illustrated a sewing machine having a frame including a bed 1 from one end of which rises a standand 2 carrying a bracket arm 3 terminatingV in a head 4 overhanging the bed 1.

The presser mechanism of the machine comprises a short hollow presser bar 5 mounted for vertical sliding movement in a bushing 6 in the bottom of the head 4. At its lower end, the presser bar 5 has secured thereto by a screw 7 a presser foot 8. The presser bar 5 has an axial bore 9 opening into the upper end thereof, in which bore is mounted a coil spring 19 that bears, at its lower end against the bottom of the bore 9 to bias the presser bar downwardly. At its upper end, the spring 10 bears against an `adjustable rod 11 extending into the bore 9. The rod` 11 is integral with a threaded member 12 that is screwed into a threaded bore in the top of the head 4, the member having a knurled head 13 for manually turning the same.

A collar 14 is secured to the presser bar 5 near the top thereofby a split ring connection having a clamping 2, screw 15. To prevent turning of the presser bar, the collar 14 has a laterally extending arm 16 the free end of which slides in -a vertical groove in a Wear plate 17 secured by screw 18 to a lug 19 in the head 4.

The presser lifter mechanismV comprises, ashaft 20 journaled transversely of the machine through the upper part of the standard 2 in

bearing bosses

21 and 22. The shaft 20 projects through the rear wall of the standard 2 and on the end thereof has secured` a presser lifter lever 23 which may be connected in the usual manner toa foot treadle (not shown). Adjacent to the front wall of the standard 2 the presser lifter shaft Z0 has secured thereto by a split ring` connection including a clamping screw 24, a vertically arranged bifurcated crank arm 25 the upper end of which is pivotally connected by a pivot screw 26 to one end of fa horizontally disposed link 27 arranged longitudinally of the bracket arm 3. A coil tension spring 28 is connected at one end tothe link 27 and at the other end `to the bracket arm 3 to bias the link 27 to the left as seen in Figs. 1 and 2. The other end of the link 2.7 is connected by a pivot'screw 29to a bifurcated vertical arm 30- of la bell crank lever 31 secured at its hub` to a pivot stud 32,by a set screw 33. The stud 32, is pivotally mounted in a horizontal bore in a boss 34 in the head 4 and isheld against axial movement by the hub `of the bell crank lever 31 anda washer 35 secured to the end` of the pivot stud 32 by a screw 36. The opening in the head through which the stud 32 is inserted is normally closed, by a, cap screw 37.

The bell crank lever 31 has a second arm- 38 which is arranged horizontally., The, free end of the arm 38 is pivotally connectedto the upper end of a link 39which is connected at its lower end to the farm 16 on the collar 14 by means of a screw 4 0 passing loosely through, avertically elongated slot 41 in the link 39,. and threaded into the arm 16. The screw 40 and slot 41 provide a lost motion connection permitting limited rising and falling motion of the presser bar 5. as thethickness of the work varies without transmitting the motion to the presser lifter mechanism.

In View of thefact that there is illustrated a two needle, sewing machine, the. needle thread tension mechanism comprises a pair of identical thread tension devices42 and 43, one for each of the needle threads. Each of the

devices

42 and 43 has a central mounting stud 44 having an integral collar 45 intermediate its ends and a pair of opposed tension discs 46 mounted thereon. The discs 46 are biased into operativeengagement with each other by a coil spring 47 surrounding the stud 44 and acting on `the outer one of the discs 46 with the inner one of-the discs 46 abutting against the collar 45. At its outer end, the spring 47 abuts against a nut 48 threaded onto the stud 44 and providing means for adjusting the compression of the spring 47. In the-usual manner, there is prof vided a sleeve 49 having a finger 50 disposed in an axially arranged slot 51 extending inwardly from the free end of the stud 44 that prevents rotation of the sleeve 49 relative to the stud, and having a flange 52 disposed between the end of the spring 47 andthe nut 4S. The flange 52 has a serrated face in engagement with the inner face of the nut 48 to resist rotation of the nut 48- relatively to the sleeve 49` and thus relatively to the stud 4.4. The inner end of the stud 44 has a neck 53 and a reduced threaded terminal portion 54 withy a shoulder 55 at the juncture of the two.

Each of the studs 4 4` hasthe threaded portion 54 thereof extending loosely through apertures in a pair of thread guides 56 and S7 which are clamped between the shoulder 55 and the surface of a mounting plate 58, the mounting plate 5S having. an aperture through which the threaded porti-on 54 of the stud 44 loosely extends. The thread guide 56 comprises an arm 59 having thread eyes 60 and the thread guide 57 comprises a pair of diverging

arms

61 and 62 having

thread eyes

63 and 64 respectively.

The stud 44 of the tension device 42 is secured to the mountingf plate 58 by a nut 65 while the stud 44 of the tension device 43 is threaded into a boss 66 on the standard,2 to `secure the mounting plate 58 to the standard. Also to secure the mounting plate 58 to the standard, there is provided a screw 67 having a head 68 and a neck 69 which is of a larger diameter than the threaded shank (of the screw to provide a shoulder 70. The screw 67 is threaded into a boss 71 on the standard 2 with a spacer 72 disposed between the shoulder 70 and the mounting plate 58, the spacer 72 being equal in thickness to the combined thicknesses of the

thread guides

56 and 57.

The tension releasing mechanism comprises a slide plate 73 having longitudinally elongated slots 74. The slide plate 73 is arranged between the spacer 72 and the head 68 of the screw 67 and between the thread guides 57 and the collar 45 on the studs 44 with the neck 69 on the screw 67 and the necks 53 on the studs 44 disposed in the slots 74. The

necks

69 and 53 are long enough to accommodate the slide plate 73 for longitudinal sliding movement as provided by the slots 74 and are of a diameter only slightly less than the width of the slots 74 to guide the slide plate 73 in sliding.

A releasing pin 75 is struck out of the slide plate 73 adjacent to each of the

tension devices

42 and 43 and is arranged to enter between the tension discs 46 of the respective tension device when the slide plate 73 is actuated. To move the slide plate 73 there is provided on the end of the presser lifter shaft a crank arm 76 having a crank pin 77 at the end thereof. The crank pin 77 extends into a slot 78 in the slide plate 73, which slot includes a first portion 79 having a radial displacement relative to the axis of the presser lifter shaft 20 and a second portion 80 formed concentrically relatively to the axis of the shaft 20. Because of the lost motion connection in the presser lifter mechanism between the link 39 and the arm 16, which is designed to permit limited rising and falling of the presser bar 5, in accordance with variations in the thickness of the work without transmitting this motion to the presser lifter mechanism, the initial actuation of the lever 2.3 will rotate the shaft 20 to take up the lost motion in the presser lifter mechanism and will not raise the presser foot 8 from the work. It is this initial rotation of the shaft 20 that is used to effect release of the needle thread tension. Upon the initial rotation of the shaft 2t), the crank pin 77 cooperates with the radial displacement portion 79 of the slot 78 to eect a cam action upon the slide plate 73 to force the plate from its normal position as seen in Fig. 3 to the left as seen in Figs. 4 and 5. This movement of the slide plate 73 forces the releasing pins 75 between the tension discs 46 to move them out of cooperative engagement to release the tension placed thereby upon the needle threads. Upon continued rotation of the shaft 20 to lift the presser foot 8 from the work, the crank pin 77 cooperates with the concentric portion 80 of the slot 78 to hold the slide plate 73 with the releasing pins 75 in tension-releasing position without effecting any further penetration of the pins 75 between the discs 46. The primary advantage of this construction is that the tension mechanism is completely released independently of the amount that the presser foot 8 is raised from the work, which varies considerably with the operator and the work or operation being performed. At the same time, there is no danger that the releasing pins 75 will be forced against the periphery of the discs 46 with the consequent straining and warping of the parts.

Having thus described the nature of the invention, what I claim herein is: Y

1. In a sewing machine having a frame, a thread tension device including a stud carriedv by said frame, a pair of opposedV tension discs loosely mounted upon said stud and spring means urging said tension discs into operative engagement for placing a tension upon a thread disposed between the same, a plate carried by said frame and mounted for sliding movement along a line in a plane normal to the axis of said stud, a releasing pin carried by said slide plate and arranged to penetrate between said discs upon sliding movement of said plate thereby to move said tension discs out of operative engagement, said plate having a slot, a shaft journaled in said frame on an axis parallel to said stud, operator controlled means for effecting oscillation of said shaft, a crank pin carried by said shaft, said slot including a rst portion formed with a radial displacement and a second portion formed concentrically with respect to the axis of rotation of said crank pin, said crank pin extending into said slot so that upon rotation of said shaft said crank pin will cooperate initially with said radial displacement portion of the slot to effect a cam action on said plate to move said plate and thus project said releasing pin between said tension discs to a predetermined extent and thereafter. upon continued rotation of said shaft said crank pin will cooperate with said concentric portion of said slot to hold said plate with said releasing pin in tension-releasing position without effecting any further penetration between said discs by said releasing pin.

2. In a sewing machine having a frame, a presser lifter mechanism including a presser lifter shaft journaled transversely of said frame, operator controlled means for effecting oscillation of said presser lifter shaft, a thread tension device including a stud carried by said frame and arranged parallel to said presser lifter shaft, a pair of opposed tension discs loosely mounted on said stud, and spring means urging said tension discs into operative engagement for placing a tension upon a thread disposed between the same, a plate carried by said frame and mounted for sliding movement along a line in a plane normal to the axis of said stud, a releasing pin carried by said slide plate and arranged to penetrate between said discs upon sliding movement of said plate thereby to move said tension discs out of operative engagement, said plate having a slot including a first portion formed with a radial displacement and a second portion formed concentrically with respect to the axis of rotation of said presser lifter shaft, a crank pin carried by said presser lifter shaft and extending into said slot so that upon rotation of said presser lifter shaft to actuate said presser lifter mechanism said crank pin will cooperate initially with said radial displacement portion of the slot to effect a cam action on said plate to move said plate and thus project said releasing pin between said tension discs to a predetermined extent and thereafter upon continued rotationof said presser lifter shaft to effect further actuation of said presser lifter mechanism, said crank pin will cooperate with said concentric portion of said slot to hold said plate with said releasing pin in tension-releasing position without effecting any further penetration between said discs by said releasing pin.

3. In a sewing machine having a frame, a presser lifter mechanism including a presser lifter shaft journaled transversely of said frame, operator controlled means for effecting oscillation of said presser lifter shaft, a thread tension device including a stud carried by said frame and arranged parallel to said presser lifter shaft, a pair of opposed tension discs loosely mounted on said stud, and spring means urging said tension discs into operative engagement for placing a tension upon a thread disposed between the same, a mounting plate, means including said stud for securing said mounting plate to said frame with said mounting plate arranged in a plane normal to said stud, a sliding plate arranged parallel to and in sliding engagement with said mounting plate for sliding movement along a line in a plane parallel to said mounting plate, said sliding plate having a slot through which said stud extends and elongated in the line of movement of said sliding plate to accommodate the sliding movement thereof, a releasing pin on said sliding plate and arranged to penetrate between said discs upon sliding movement of said plate thereby to move said tension discs out of operative engagements, said plate having a slot including a first portion formed with a radial displacement and a second portion formed concentrically with respect to the axis of rotation of said presser lifter shaft, a crank pin carried by said presser lifter shaft and extending into said slot so that upon rotation of said presser lifter shaft to actuate said presser lifter mechanism said crank pin will cooperate initially with said radial displacement portion of the slot to effect a cam action on said sliding plate to move said sliding plate and thus project said releasing pin between said tension discs to a predetermined extent and thereafter upon continued rotation of said presser lifter shaft to effect further actuation of said presser lifter mechanism said crank pin will cooperate with said concentric portion of said slot to hold said sliding plate with said releasing pin in tension releasing position without effecting any further penetration between said discs by said releasing pin.

4. In a sewing machine having a frame, presser mechanism carried by said frame, presser lifter mechanism comprising a presser lifter shaft journaled transversely of said frame, means including a lost motion connection for operatively connecting said presser lifter shaft to said presser mechanism for lifting said presser mecha nism upon rotation of said presser lifter shaft, thread tension mechanism including a stud carried by said frame, a pair of opposed tension discs loosely mounted upon said stud, and spring means urging said tension discs into operative engagement for placing a tension upon a thread disposed between the same, a plate carried by said frame and mounted for sliding movement along a line in a plane normal to the axis of said stud, a releasing pin carried by said slide plate and arranged to penetrate between said discs upon sliding movement of said plate thereby to move said tension discs out of operative engagement, said plate having a slot including a rst portion formed with a radial displacement and a second portion formed concentrically with respect to the axis of rotation of said presser lifter shaft, a crank pin carried by said presser lifter shaft and extending into said slot so that upon rotation of said shaft said crank pin will cooperate initially while the lost motion in the presser lifter mechanism is being taken up with said radial displacement portion of the slot to effect a cam action on said plate to move said plate and thus project said releasing pin between said tension discs to a predetermined extent and thereafter upon continued rotation of said shaft to lift said presser mechanism said crank pin will cooperate with said concentric portion of said slot to hold said plate with said releasing pin in tension-releasing position without effecting any further penetration between said discs by said releasing pin.

References Cited in the file of this patent UNITED STATES PATENTS 415,951 Steward Nov. 26, 1889 820,290 Drysdale May 8, 1906 1,071,451 Moffatt et al. Aug. 26, 1913 1,118,710 Weis Nov. 24, 1914 1,792,387 Moffatt et al Feb. 10, 1931 1,823,817 Christensen Sept. 15, 1931