US2452756A - Sewing-machine hook mechanism - Google Patents

Description

SEWING MACHINE HOOK MECHANISM Filed Jan. 15, 1945 5 5 INVENTOIR i2 Wm/Am /f Ham/14mm Patented Nov. 2, 1948 SEWING-MACHINE HOOK MECHANISM Richard K. Hohmann, Jamaica, N. Y., assignor to White Sewing Machine Corporation, Cleveland, Ohio, a corporation of Delaware Application January 15, i945, Serial No. 572,931

6 Claims.

The general object of the present invention is to provide an improved sewing machine mechanism of the type in which a needle thread loop is passed around a bobbin holder by a rotary hook. The term rotary book as used herein generically includes a revolving hook which in operation turns continuously in one direction, and an oscillating hook which turns back and forth about an axis through an arc which ordinarily is slightly greater than 180".

More specifically stated, the general object of the invention is to provide a sewing machine mechanism comprising a hook turning about a Vertical axis and formed with a chamber open at its upper end and a bobbin holder normally received in said chamber, and in which the hook and bobbin holder have cooperating guide surfaces through which the bobbin holder is normally held by gravity in operative relation with the hook, and which permit the bobbin holder to be moved vertically into and out of the bobbin holder chamber. In a preferred form of the invention, a guard member is mounted on the supporting frame work for movement into and out of a position in which it extends over the bobbin holder without normally engaging the latter, but is operative to prevent the holder from moving up out of its normal position as a result of vibration or some abnormal operating condition.

A specific but practically important object of the present invention is to provide an oscillating hook mechanism having the above mentioned characteristics and comprising elements so disposed, and having their movements so timed that the tendency of the bobbin holder to share oscillating movements of the hook as a result of their frictional engagement, is utilized to open a thread passage between the bobbin holder and a stationary retainer element to accommodate the movement of the needle thread loop into the space between the bobbin holder and retainer element at the beginning of each loop forming operation, and to open a second thread passage between said holder and retainer for the escape of the thread loop as each loop is being completed.

The variousfeatures of novelty which char vantages and specific objects attained by its use;

reference should be had to the accompanying drawings and descriptive matter in which I have 1" .4 illustrated and described preferred embodiments of the invention.

Of the drawings:

Fig. 1 is a plan view of an oscillating hook and associated bobbin holder with the hook in the position occupied at the beginning of its loop drawing movement;

Fig. 2 is a view taken similarly to Fig. 1 but omitting parts shown in Fig. 1, and showing the hook at the end of its loop drawing movement and the loop fully expanded;

Fig. 3 is a view similar to Fig. 2 and showing the hook in the same position, but showing the loop in a later, much contracted condition;

Fig. 4 is a view taken similarly to Fig. 2, but with the hook in the position occupied after a slight return movement from the position shown in Fig. 3;

Fig 5 is an elevation in section on the broken line 5-5 of Fig. 1;

Fig. 6 is an inverted plan view of the bobbin holder; and

Fig. 7 is an inverted plan View of the mechanism giving oscillating movements to the vertical hook shaft.

In the form of construction shown in the drawing, a vertically disposed hook shaft l is given oscillating movements by means comprising an arm 3 secured to the shaft l adjacent its lower end, and a link 4 connecting the free end of the arm 3 to one end of an oscillating lever 5. The latter is journaled on a stationary stud shaft 5. The second end of the lever 5 is connected by a pivot 6 to one end of the link I. The latter is adapted to be given reciprocatory movements in the general direction of its length in timed relation with those of an associated, vertically movable needle and needle reciprocating mechanism. Said mechanism is not illustrated and need not be further described as it forms no part of the present invention and may be of old and well known type.

At its upper end the hook shaft supports and is rigidly connected to a loop-taker or hook member 8. The latter as shown is in the form of a shallow cup shaped body coaxial with the shaft and having an apertured bottom wall 9, and is characterized by the fact that its upper end portion I0 is in the form of a thin cylindrical flange or rib coaxial with the shaft I. The lower end of the flange portion or rib I0 is surrounded by an annular horizontal bearing surface II. The rib I0 is cut away at opposite sides of the shaft l to form thread notches I2 and I3. The notch I2 is of such depth that its bottom wall is below the bearing surface I l. One end wall of the notch I2v is undercut to form a hook l4 adapted to take a thread loop from the coacting needle, when the latter is in the position in which it extends downward through the work and needle hole in the needle plate. The work and needle plate are not shown but the dotted circle I5 represents the outline of the needle hole. The two end walls of the notch [2 are oppositely inclined to one another and to a plane radial to the hook shaft and passing between said walls, so that the outer ends of said walls are more widely separated than are their inner ends. The notch l3 at the opposite side of the loop-taker from the notch 12 may be formed wholly in the rib I0 with its bottom edge slightly above the bearing surface H.

The annular rib or flange IE! and the surrounding bearing surface ll provide supporting and guiding surfaces for a bobbin holder IS. The

latter is formed with a cup shaped chamber I! open at its upper end to receive a thread bobbin l8 which may be of conventional form. As shown, the vertical axis of the bobbin chamber H is laterally displaced from the axis of the hook shaft In. The bobbin holder includes an are shaped flange portion 19 extending radially away from the wall of the bobbin chamber at the side of the latter remote from the axis of the hook shaft. The. underside of the flange 19 forms a horizontal bearing surface which is above and in engagement with the bearing surface ll of the loop taker 8 in the operatin condition of the apparatus. An are shaped groove 20 coaxial with the shaft 1 and having the same radius of curvature as the rib I0, is formed in the flange I 9. The groove 20 extends upward from the bottom side of the flange l9 and is shaped and proportioned to receive a corresponding portion of the loop taker cylindrical rib I0. bobbin, holder I6 is thus accurately positioned in the loop taker. At one end, the flange i9 is cut away toform a spaced apart pair of horn portions 2 I. and 2 -2.

The bobbin holder I6 is prevented from sharing the general angular movements of the oscillating hook 8 by a retaining element 22'. The latter comprises a plate-like body portion held stationary by screws 23 at the outer side of the rotary hook, and. comprises an arm 24 extending under the horn 22- and terminating; in a vertically disposed thread guide portion 25 with its upper end portion loosely received between the horn portions 22 and 2| of. the flange l9. As shown, the thread guide part 25 is. shaped to form a vertical trough shaped needle channel open at its outer side. The side walls of said needle channel are located at opposite sides of the plane including the axis of the hook shaft 1 and the axis of the opening 15 in the needle plate. member. The hornszl and Hand the part 25 are proportioned and disposed to providea clearance space, serving as a thread passage between the guide 25 and one or the other of the horns 2i and 22 in regular alternation as hereinafter explained.

A lever element 'journalled on the stationary pivot 3i normally extends over'the flange portion 19 of the bobbin holder. without directly engaging. the latter, but separated therefrom by a distance too'small to permit objectionable movement of the bobbin holder up from its-normal position in the hook as a result of vibration or other abnormal-condition which mayoccasionally develop, As, shown, the arm 30 is biased by a springv 3 2-toturn fromthe full line position into In; operation, the

the dotted line position shown in Fig. 1. In the latter position, the arm 30 does not extend over the bobbin holder. The arm 30 is normally held in its full line position by a latch member 34 in engagement with a hook portion 33 of the arm 30. The member 34 is mounted on a stationary pivot 35 and biased by a spring 36 for movement into its latchin position. As shown in Fig. 5, the juxtaposed surfaces of the arm 3'0 and bobbin holder flange 19 are similarly inclined to the looptaker axis and are separated by a clearance space through which the thread loop drawn by the beak l4 may freely pass,

In operation, the loop-taker beak or hook l4 engages the needle thread 40 as it moves counterclockwise from its position shown in Fig. 1. As the counter-clockwise movement of the hook progrosses, the needle thread loop is moved through the space between the retainer part 25 and the horn 2|, and the upper side of the loop is drawn over the top of the bobbin holder, while the under side is. drawn under the bobbin holder. As the counter-clockwise movement continues and the hook approaches the position shown in Fig. 2, the needle thread loop is drawn away from the hook by the take-up mechanism of the sewing machine which then rapidly contracts the loop and finally pulls it off the born 22'.

As the hook begins to turn in the counter-clock wise direction, the bobbin holder moves with the hook under the action of friction to, open the previously closed clearance between the horn 2| and retainer 25, thereby providing the open thread passage shown in Fig. 1 through which thethreadloop passes preparatory t its movement about the body of the bobbin holder. Similarly when the hook starts: to move clockwise back from its position shown in Fig. 2, the bobbin holder is moved through the small angle necessary to bring the horn 2! into engagement with the retainer 25- and to separate the horn 22 from the retainer. Thisprovides a clearance space or thread-passage through which the needle thread loop passes as shown in Fig. 4, as the loop is being drawn off the horn 22 and tightened uparound the portion, of the bobbin thread 41 extending from the-bobbin thread tension spring 42 carried by the bobbin;

holder, to the underside of the portion of the work directly beneath the needle plate opening I 5.

Except duringtheperiods in which the beak I4 is at or adjacent to the ends of its path of movement, and hence is stationary, or, is moving with relative slowness, the horns 2| and 22 are directly above and engage the upper edge of the rib l0.

5 The horn 22' is angularly displaced from the groove 20 to a substantial extent asplainly appears in Fig. 6, and the rib l0 and horn 22 thus cooperate to insure against risk of tilting movement of the bobbin holder in the direction to lower the horns 2| and, 22. Such tilting movement might otherwise occur when the loop taker is moving at relatively high speed; As previously explained, the thread notch I2 is so located that the rib Hl does not interfere with the movement,

of the'threadloop onto the'bobbinholder. The

thread notch I3 is solocatedthat the rib Ill doesnot interfere with the movement of the thread loop off thehQrn'ZZ-in the final stage of each loop forming operation.

As previously explained, a bobbin holder may be m-ountedin an open top loop-taker in the general manner shown inthe drawing when the looptaker is of thetype revolving continuously inone direction, as well as when theloop-taker oscilelates as in the particular construction shown' in,

the drawings; In accordance with thefusual practice of the art, the bobbin holder used with a continuously revolving hook would ordinarily have a bobbinchamber coaxial with the hook.

Withthe continuously revolving hook, however,

the frictional tendency of the bobbin holder to share the rotative movement of the looper can not be used to alternately open loop receiving and discharging thread passages for movement of the thread loop over and off of the bobbin holder.

The cooperating cylindrical guide surfaces formed by the walls of the rib H! and groove 2S are of special utility when a considerable portion of the bobbin holder is cut away so that the coactive guide surfacesof the bobbin holder and loop-taker are in operative contact through an angle about the loop-taker axis which is substantially less than 360. As those skilled in the art will realize the cutting away of the bobbin holder'shown in the drawings, not only reduces the bobbin holder weight, but facilitates and expedites the movement of the loop off the bobbin holder, and permits the extension of the thread guide support, comprising parts 22' and 24, down through the loop-taker and beneath the horn 22, and the extension of the thread guide part 25 up through the peripheral notch formed in the bobbin holder, and the opposite side walls of which terminateat their outer ends in the horns 2| and 22. The engagement of the upper edge of the rib ID by the horn 22 contributes to bobbin holder stability notwithstanding the cutting away of relatively large adjacent portions of the bobbin holder. For analogous reasons it is desirable in many cases to cut away relatively large portions of bobbin holders which are coaxial with the loop-taker.

In the arrangement shown the needle axis is parallel to the loop-taker axis and between the latter and the path of movement of the looptaker beak M. This permits the bobbin to be located at the left side of the needle as seen from the operators normal position. This makes the bobbin more accessible than it would be if the entire loop-taker were at the right side of the needle. In the latter case however, the looptaker could be smaller in diameter than is inherently possible with the arrangement shown.

The relatively large size of the loop-taker required with the arrangement shown augments the need for cutting away a relatively large portion of the bobbin holder and for laterally displacing the bobbin axis from the hook axis, and augments the advantage obtained with the cylindrical guide surfaces formed by the walls of the rib l6 and groove 20.

To control the movement of the thread loop as it passes from the condition shown in Fig. 2 into that shown in Fig. 3, a thread finger 43 secured to the upper side of the part 22 extends over a portion of the bobbin holder adjacent to the arm 24 with suitable clearance. The clearance provided accommodates the passage of the thread loop and permits the direct vertical movement of the bobbin holder required for the engagement and separation of the walls of the slot 20 with the rib I 0. With said walls and ribs disengaged, a slight tilting adjustment of the bobbin holder permits the latter to be moved upward away from the loop-taker.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A sewing machine mechanism, comprising in combination a loop taker element turning about a vertical axis and having a bobbin holder seat at its upper side including an uprising rib portion of said element extending circularly about said axis, and a bobbin holder element normally held in engagement with said seat by gravity and vertically movable toward and away from said seat, and formed with a groove in the formof an arc extending circularly about said axis for substantially less than 360, and entered by said rib, said bobbin holder element having a peripheral portion cut away to form horns separated by a notch and at least one of which is angularly displaced about said axis from said groove and extends over said rib whereby the latter restricts the downward displacement of said horn, and a stationary needle guide extending through said notch and cooperating with said horns to restrict angular movement of the bobbin holder element about said axis in either direction.

2. A sewing machine mechanism comprising in combination a loop taker element oscillating about a vertical axis and comprising a bobbin holder chamber open at its upper side, a bobbin holder element normally received in said chamber and vertically movable into and out of the latter, one of said elements being formed with a cylindrical rib coaxial with said axis and the other of said elements being formed with a groove extending circularly about said axis and entered by said rib and having cylindrical inner and outer walls respectively engaging the inner and outer walls of said rib, said bobbin holder element being cut away to form a peripheral notch, and a stationary bobbin holder retaining member extending through said notch and shaped and disposed to engage the bobbin holder at either side of said notch with clearance between said member and the side of the notch not engaged by said member, whereby the frictional contact of the bobbin holder element with the loop-taker element moves the bobbin holder element to open a thread passage between said member and one side or the other side of said notch on initial turning movement of the oscillating loop-taker element in one or the other direction, respectively.

3. A sewing machine mechanism comprising in combination a loop taker element oscillating about a vertical axis and comprising a bobbin holder chamber open at its upper side, a bobbin holder element normally received in said chamber and vertically movable into and out of the latter, one of said elements being formed with a cylindrical rib coaxial with said axis and the other of said elements being formed with a groove extending circularly about said axis and entered by said rib and having cylindrical inner and outer walls respectively engaging the inner and outer walls of said rib, said bobbin holder element being cut away to form a peripheral notch, and a stationary bobbin holder retaining member comprising an uprising portion extending through said notch and a supporting portion extending into said chamber through its open upper side and extending beneath a portion of the bobbin holder element at one side of said notch.

4. A sewing machine mechanism comprising in combination a loop-taker element turning about a vertical axis and comprising a bobbin holder chamber open at its upper side, and a bobbin holder element normally received in said chamber and vertically movable into and out of the latter, said '2 elements being: formed? with cooperating guide surfaces including: av cylindrical rib formedom one of said: elements and coaxial with said axis: and the :other of saidelementsbeing formed with a groove: extending circularly about: said axis and entered by. said: rib: andl'having cylindrical inner and; outer walls: respectively engaging the inner and. outer Walls of saidrib'; said" bobbin; holder element being cut away to form a peripherallnotchi and a. thread loop discharging-horn forming one other of said elements being formedwith a groove extending circularly about said. axis and entered by said rib and having cylindrical inner and'couter wallsrespectively engaging the inner and outer walls of said rib, and a member movable into and out of a position in" which it extends over said bobbin holder element and prevents the latter from moving, up out. of saidchamber.

62 A sewing machine'- mechan-ism' comprising: in combnat'ion a looptaker element turning about-a vertical axis and comprising; a: bobbin: holder chamber open at it"s':upper' side; a bobbin holtieif 1 element normally received-i said? chamber and vertically movable into and out of the= -latten', one

oft" said elements being: formed with a cylindrilza-lrib coa-xial with said axis; and the other of said elements-" being formed" with a groove; extending circularly about said! axis and entered: by: said rib andhaving cylindrical inner andv outer walls i-espect'ively engaging the inner and outer walls of said rib, a. member pivoted tov turni about; air axis from into and outof a position in-whi'ch it extendsover the bobbon holder element and prevent the. latter from moving upout of said chamber; said member being: biased-.1 for movement out" of said: position, and latching means releasably securing: member in said" position.

RICHARD K. HOHMANN;

REFERENCES CITED The following references are of record inthe file of this'pat'ent:

UNITED STATES PATENTS Number Name Date- 683,847 Catenacci et 'al Oct. 1 1901 1,996,324 Chiti Apr. 2, 1935

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