US2853035A - Rotary hooks for sewing machines - Google Patents

Description

Sept. 23, 1958 R. E. JOHNSON ROTARY HOOKS FOR SEWING MACHINES 5 Sheets-Sheet 1 Filed April 9, 1956 mmvron. Ralph E. Johnson BY W/QATTORNEY WITNESS Sept. 23, 1958 R. E. JOHNSON ROTARY HOOKS FOR SEWING MACHINES 5 Sheets-Sheet 2 Filed April 9, 1956 IN VEN TOR. Ralph E. Johnson BY Fig. 5. Q

Z TTORNEY Sept. 23, 1958 R. E. JOHNSON 5 ROTARY HOOKS FOR SEWING MACHINES Filed April 9, 195a s Sheets-Sheet :5

IN VEN TOR.

Ralph E. Johnson WITNESS W ATTORNEY 2,853,035 Patented Sept. 23, 1958 United States Patent Office ROTARY HOOKS FOR SEWING MACHINES Ralph E. Johnson, Mountainside, N. 1., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application April 9, 1956, Serial No. 576,903

19 Claims. (Cl. 112 -181) The present invention relates to a rotary hook for a sewing machine and has for a primary object to pro vide a rotary hook wherein the friction between the rotating and non-rotating components has been substantially reduced.

In rotary hooks as heretofore known, the bobbincarrier is journaled within the hook body for rotation relatively thereto by means of a bearing rib and raceway, and is restrained against rotation with the hook. A rotary hook rotates at twice the sewing speed so that in modern high-speed sewing machines which operate at up to 5000 stitches per minute, the hook rotates at speeds up to 10,000 R. P. M. At such speeds, the effects of the friction between the bearing rib and raceway are serious and lubrication of the raceway becomes very critical. Without adequate lubrication, the bearing would soon be burned out. At the same time any excess lubrication will be thrown from the hook by centrifugal force and will creep to the work-supporting surface of the machine and spoil the work. In accordance with the present invention there has been provided a rotary hook of novel construction in which there is a negligible amount of friction between the stationary bobbin-carrier and the rotating components of the hook.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements 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 it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary front elevational view of the head end of a sewing machine embodying the present invention.

Fig. 2 is an end elevational view of the machine illustrated in Fig. l with the face plate removed.

Fig. 3 is a fragmentary vertical sectional view substantially through the center of the rotary hook of the sewing machine illustrated in Fig. 1.

Fig. 4 is an elevational view of the rotary hook per se as illustrated in Fig. 1. I

Fig. 5 is a view similar to Fig. 4 but with the bobbin carrier removed.

Fig. 6 is a top plan view, partly broken away, of the rotary hook per se as illustrated in Fig. 1.

Figs. 7, 9, 11 and 13 are elevational views, some partly broken away, of the rotary hook as illustrated in Fig. 1 together with the work, which views sequentially illustrate the operation of the present-hook in stitch formation, and Figs. 8, 10, 12 and 14 are horizontal sectional views of the hook corresponding respectively to Figs. 7, 9, 11 and 13.

With reference to the drawings, the present invention is disclosed as embodied in a sewing machine having a frame including a bed-plate 1, a standard 2 rising from the bed-plate, and a bracket-arm 3 carried by the standard 2 and terminating in a head 4 overhanging the bed 1. The open end of the head 4 is closed by a faceplate 5. A throat-plate 6 is provided in the bed-plate 1 at the point of stitch formation, the upper surface of the bed-plate and throatplate comprising the worksupporting surface of the machine.

Mounted vertically in the head 4 for endwise reciprocation is a needle-bar 7 carrying at its lower end a needle 8 that is adapted to penetrate an aperture 9 in the throat plate 6. The needle-bar 7 is connected by means of a link 10 to an offset crank pin 11 on a counterbalanced crank 12 that is mounted upon the end of a driven main shaft 13 journaled longitudinally of the bracket-arm 3. Thus, as the main shaft 13 is rotated, endwise reciprocation will be imparted to the needlebar 7. The take-up mechanism of the machine is a conventional link take-up and comprises a take-up lever 14 pivoted on the offset crank-pin 11 and connected at an intermediate point to one end of an anchor link 15 that is pivoted at its other end to the head 4 by a pivot screw 16. The illustrated presser mechanism is of well-known construction and comprises a presser bar 17 mounted vertically in the head 4 for endwise sliding movement and carrying a presser foot 18 at its lower end. The presser bar 17 is urged toward the throat plate 6 by a compression spring 19 coiled about the same and acting at its lower end against a collar 20 on the presser bar and at its upper end against an adjustable bushing 21. The feeding mechanism may be of any conventional construction and is herein illustrated as having a feed-dog 22 mounted on a feed-bar 23 to which a four-motion cycle of actuation is imparted.

A rotary hook, designated generically 24, is adapted to cooperated with the needle 8 in the formation of stitches. The hook 24 is adapted to be rotated by a hook shaft 25 journaled longitudinally of the bed of the machine and connected to the main shaft 13 (connections not shown) to be driven at a two-to-one ratio with respect to that shaft, whereby the hook will make two revolutions to each reciprocation of the needle 8.

The hook 24 comprises a hub 26 journaled in a bushing 27 that is secured in a lug 28 depending from the bedplate 1. The hub 26 has an axial bore 29 extending inwardly from the inner end into which bore the hook-shaft 25 extends and in which it is secured by a set screw 30. An eccentric 31 is formed on the hub 26 and comprises a circular end portion at the forward end of the hub that is eccentric with respect to the axis of the hub. Mounted upon the eccentric 31 of the hub 26 is a cup-shaped hook frame or body 32, a ball bearing 33a being interposed between them to provide for rotation of the hub 26 relatively to the hook frame 32. The hook frame 32 is provided with an internal bobbin-carrier bearing surface which comprises a circular flange or beating rib 33 formed by inturning the free edge of the hook frame 32. The flange 33 cooperates with an external bearing surface on the bobbin-carrier comprising a groove or raceway 34 in the periphery of a bobbin-carrier 35 which is mounted in the hook frame 32. The bobbin-carrier 35 is circular and has an external diameter at the base of the groove 34 that is less than the internal diameter of the flange 33 by an amount substantially equal to the eccentricity of the eccentric 31. The bobbin-carrier 35 is supported within the hook-frame by the cooperation of the flange 33 with the'groove 34 at a point of contact which is at the point of minimum eccentricity of the hook frame 32, the bobbin-carrier 35 being held against radial movement away from the point of contact with the hook frame 32 by a wobble-plate 36 which engages against a shoulder 37 formed by a rablbet in the inner face of the bobbin-carrier about a circular opening 38 therein. The diameter of the shoulder 37 is made substantially equal to the horizontal projection of the wobble-plate 36 into the plane defined by the shoulder 37.

The wobble-plate 36 is mounted upon the end 39 of a shaft 40 that is seated in a bore 41 in the hub 26 and secured thereinby a set screw 42, a ball bearing 43 being interposed between the hub of the wobble-plate 36 and the end 39 of the shaft 40 to provide for rotation of the shaft 40 relatively to the wobble-plate. The bore 41 extends generally axially of the hub 26 but is skewed slightly so that the Wobble-plate 36 is at an angle to the bobbin-carrier. At the same time, the shaft 40 is so arranged that the center of the wobble-plate 36 is aligned with the axis of the shaft and hub 26. Thus, upon rotation of'the shaft 25, the shaft will be carried around the axis of the hub 26 so that the axis of the shaft 40 will define a cone having its apex at the 7 center of the wobble-plate 36, and therefore the only motion-imparted to the plate 36 will be wobbling about its' center as successive portions thereof are extended 7 into cooperation with the shoulder 37 of the bobbin-carrier 35. The timing of the wobble-plate 36 is such that the portion in cooperation with the shoulder 37 of the bobbin-carrier is directlyopposite the point of maximum eccentricity of the hook frame 32, or conversely, coincides with the point of minimum eccentricity of the hook frame. Therefore, as the eccentricity of the hook frame 32 is rotated by rotation of the eccentric 31, the point of contact between the wobble-plate 36 and the bobbin-carrier 35 will also be rotated so that the bobbin-carrier will always be held against radial movement inwardly by the wobble-plate at the point of minimum eccentricity of the hook frame 32 and thus is always supported by the cooperation of the flange 33 and groove 34.

To hold the bobbin-carrier 35 against rotation there is provided a rotation restraining finger 44 engaging in a slot 45 formed in an arm'46 integral with the bobbincarrier 35. A needle aperture 47is provided in the upper face of the bobbin-carrier 35 adjacent to the arm 46 and a thread clearance opening 48, Fig. 6, is provided at the rear top edge thereof. In the usual manner, there is mounted in the bobbin-carrier 35 a bobbin case 49 having a bobbin 50 therein; The bobbin case 49 is provided with a conventional bobbin thread tension spring 51 and latch means 52.

The loop seizing element of the present machine comprises a sheet metal hook-arm 53 secured to the eccentricend 31 of'the hook hub 26 by an elongated screw 54 extending through the hub 26 and threaded into the hook-arm53. A notch 55 is formed in the edge of the hook-arm 53 adjacent to and conforming to the configuration of the wobble-plate shaft 40. The notch 55 is arranged so that the forces tending to retard rotation of the free end of the hook-arm 53, such as the effort required to expand the needle thread loop, will force the edge of the hook-arm 53 against the shaft 40 with the shaft seated in the notch 55.

The hook-arm 53 is arranged perpendicular to the hub 26 and the free end thereof is bent around the edge of the Wobble-plate 36 and bobbin-carrier 35 into the crescent shaped gap between the periphery of the bobbincarrier 35 and the inner edge of the flange 33 of the hook frame 32, which gap is formed at the point of maximum eccentricity of the hook frame by holding the smaller bobbin-carrier in contact with the hook frame at the point of minimum eccentricity of the hook frame. A -hook element 56 is formed upon the free end of the hook arm 53 andincludes a loop-seizing beak 57. An

ear 58'is bent normal to the hook arm 53 at the outer rear portion of the hook element 56 to provide a loop "detaining shoulder 59.

The timing of the hook-element 56 is fixed by the In the preferred embodiment of the invention'the hook-element 56 is timed so *hookframe 32. While-the dimensions are not critical,

" the bobbin carrier 35.

that the loop-seizing beak 57 precedes by about forty frame 32 which, at the same time, is the point of maximum opening of the crescent-shaped gap between the hook frame and the bobbin-carrier. The disposition of the hook-element 56 in the crescent-shaped gap is constant.

With reference to Figs. 7 and 8, the illustrated point in the stitching cycle is with the extremity of the hook beak 56 at forty degrees beyond the top center) position. At this point, the maximum eccentricity of the hook frame 32 relatively to the axis of the hub 26, and consequently the maximum opening of the crescent-shaped gap between the hook frame 32 and bobbin-carrier 35, is at the top center. At the same time, the minimum eccentricity of the hook frame 32, and consequently the point of contact between the flange 33 of the hook frame and groove 34 of the bobbin-carrier, is at the bottom center. The wobble-plate 36 has the bottom center portion thereof projected toward. the bobbin-carrier and in cooperationwiththe shoulder 37 to hold the bobbin-carrier 35 against radial movement inwardly away from the point of minimum eccentricity of the'hook frame 32. Since the difference between the diameters of the cooperating surfaces of the bobbin-carrier 35 and hook frame 32 is equal to the eccentricity of the hook frame '32 relatively to the axis of the hub26, the bobbin-carrier is thus supported within the hook frame.

As the hub 26 rotates, the rotation of the eccentric 31 will rotate the point of minimum eccentricity of the hook frame 32 in the direction of the arrow A. At the'same time, the motion of the shaft 40 about the axis of the hub 26 will cause the plate 36 to wobble or precess about its-center so that successive portions thereof are projected into cooperation with the shoulder 37. The wobbling of the plate 36 is in timed relation with respect to the rotation of'the eccentricity of the hook frame 32 so that the portion of the wobble-plate 36 in cooperation with the shoulder 37 always corresponds to the point of minimum eccentricity of the hook frame 32 whereby the bobbin-carrier is continuously held during operation.

There is frictional engagement between the shoulder '37 and the cooperating portion of the wobble-plate 36,

bearing 43.

There'is also frictionalengagement' between'the hook frame 32 and bobbin-carrier'35 at the groove 34 .and flange 33. The bobbin-carrier is stationary so the friction'tends toprevent sliding of the hook frame 32 relatively to the bobbin-carrier 35, so the hook frame 32 will roll about the p'eripheryofthe bobbin-carrier 35 in a mannersimilar to that of a planetary gear,'the rotation of the hub 26 relatively to the hook frame 32 being taken up in the bearing 33a. Thus,up0n' one revolution of the hook shaft 25, the hook frame 32 will be moved through one complete cycle by'the eccentric 31 in which cycle it will have rolled completely around: the periphery of Becauseof the larger circumference of the contacting surface of "the' hook frame 'relatively'to the contacting surface of the bobbin-carrier, when the hook-body is moved through one complete cycle, it will rotate 'in the reverse direction relatively to the bobbin-carrier by an'amount equal to the difference in circumferences. This'is the only rotation of 'the hook frame 32and' it is taken'up in the bearing 33a, acting to reduce'rotation inthatbearing between the hub" 26 and in the illustrated embodiment of the invention, assuming R. 'P. M. and the hook .frame 32 will. be :rotating'at .it contacts the shoulder 59.

approximately. 900 R. P. M. The rotation in the bear ing 33a, which is the rotation of the hook frame relatively to the hub, will therefore be approximately 9100 R. P. M. Rotation in the bearing 43 will be 10,000 R. P. M.

For convenience, the motion of the hook frame 32 may be considered to be epicyclic, i. e., the rolling of a circle about the convex side of another circle which is stationary in which the bobbin-carrier bearing groove 34 is the stationary circle and the hook frame bearing flange 33 is the circle which rolls about the convex side of the periphery thereof. In the present case, the stationary circle is arranged internally of the rolling circle, and consequently, in the relative rotation between the hook frame and bobbin-carrier, a point on the periphery of the hook frame bearing flange 33 will contact the periphery of the bobbin-carrier bearing groove 34 only once in one revolution plus the difference in the circumferences.

In view of the fact that there is only rolling and no sliding contact between the hook frame 32 and bobbincarrier 35, and that the only relative motion between the bobbin-carrier 35 and the wobble-plate 36 is the moving of the successive portions of the wobble-plate against the shoulder 37 and being retracted therefrom, the friction between these surfaces has been so reduced that there is virtually no need for lubricants. All of the relative motions are taken up in the bearings 33a and 43, which are not only well adapted to take up the motion, but can be readily lubricated without having any excess lubricant thrown off to find its way to and thus spoil the work.

To consider the stitching, in operation the needle 8, when it descends, passes through the work M and the needle aperture 9 in the throat plate 5 in the usual manner. Upon reaching the point of maximum penetration, it rises and in so doing casts a loop of the needle thread N into the path of the loop-seizing beak 57 of the hook element 56, which loop is then entered by the advancing beak 57. The loop of the needle thread N is forced back upon and thus spread by the hook-element 56 as it continues to advance, as illustrated in Figs. 7 and 8. For convenience, that portion of the needle thread N extending from the beak 56 to the work is denoted the work limb W, while that portion extending from the beak to the needle is denoted the needle limb L. The groove .34 in the periphery of the bobbin-carrier 35 is not continuous but has a gap therein at the top to provide clearance in which the loop of thread is free to slide back upon the hook-element S6. The beginning of the raceway beyond this gap in the direction of rotation of the hook-element, indicated by the arrow A, constitutes a loop-detaining shoulder 60. Thus, as the hook-element 56 advances, the needle limb L of the thread N is stripped from the lower edge thereof and held by the shoulder 60 in a manner common to rotary hooks. limb L and the work limb W of the needle thread N are thus directed to the opposite sides of the groove 34 and will eventually pass over the opposite faces of the bobbincarrier 35 as the loop of needle thread N is passed around the bobbin-carrier 35 and the enclosed bobbin 50 to become concatenated with the bobbin thread B.

As the hook continues to rotate, the loop of needle thread N moves back upon the hook-element 56 until Thereafter, the loop is pulled by the hook-element 56 and expanded to pass over the bobbin-carrier 35. The work limb W of thread N passes across the front of the bobbin-carrier 35 while the needle limb'L lays on the periphery of the bobbin-carrier to the rear of the groove 34 until it reaches cast-off position, which is substantially as illustrated in Figs. 9 and 10. The needle limb L of the thread N then slides off the periphery of the bobbin-carrier and begins to slide across its rear face.

Shortly beyond the position illustrated in-Figs. 9 not 10, the loop of needle thread has reached the point pf The needle 4 were maximum expansion. The take-up mechanism, which has been giving up thread into the system now reverses and begins to withdraw the thread. In the intermediate position illustrated in Figs. 11 and 12, the needle limb L of the thread isbeing withdrawn at a rate faster than the rotation of the hook-element 56 and is about to be drawn off the hook-element. As seen in Figs. 13 and 14, the loop of needle thread N has completed its passing about the bobbin-carrier to encircle the bobbin thread B, and has been substantially withdrawn. To complete the stitching cycle, the needle-thread loop, as it is drawn up, will escape between the rotation restraining finger 44 and the slot 45 in the arm 46 of the bobbin-carrier, and will finally be set in the work. Thereafter, the takeup will pull into the system enough thread for the next stitch, the feeding mechanism will advance the work, and the needle will descend to begin another stitch.

In order for the loop of needle thread N to pass about the bobbin-carrier 35, it must pass between the bobbincarrier and its supporting means. The crescent shaped gap between the periphery of the bobbin-carrier and the flange 33 of the hook frame 32 provides the clearance about the periphery of the bobbin-carrier, the loop riding in this gap with the hook element 56 as it passes around the periphery. The other portion of the bobbin-carrier supporting means, which is the wobble-plate 36, contacts the bobbin-carrier at a point that progresses about the bobbin-carrier approximately in front of the beak 57 of the hook-element 56. Because of the angle of the wobble-plate 36 with respect to the bobbin-carrier 35, the major portion of the wobble-plate 36 is not in contact with the bobbin-carrier and so there is clearance between the two in which the needle limb L of the thread N is free to slide over the bobbin-carrier. This clearance appears clearly in Figs. 9 and 10. In the position illustrated in Figs. ll and 12, the point of contact between the wobble-plate 36 and the shoulder 37 of the bobbin-carrier 35 is passing over the needle limb L of the thread N. There is therefore provided the thread clearance opening 48 in the bobbin-carrier 35 to accommodate this limb L of the thread N as the point of contact between the wobble-plate 36 and bobbin-carrier passes.

As the needle limb L of the thread N slides across the rear face of the bobbin-carrier 35 from the position illustrated in Figs. 9 and 10, it will fall into the opening 48 before the contacting point of the wobble-plate 36 closes the same. At this point, the needle limb L of the thread N passes through the opening 48 and between the wobble-plate 36 and the rear face of the bobbin 5t).

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

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

1. In a sewing machine, a rotary hook mechanism comprising a hook frame having an .internal circular bobbin-carrier bearing, a bobbin-carrier mounted in said hook frame and having a circular bearing at the periphery thereof of a diameter less than the diameter of the bearing of the hook frame, means for holding said bearings radially in engagement at a point of contact to produce between said bearings a crescent-shaped gap disposed diametrically opposite from the point of contact and for rotating the point of contact between said bearings about the periphery of said bobbin-carrier, a rotary hook element disposed in the gap, and means for moving said hook-element about said bobbin-carrier in unison with the rotation of the point of contact, said hook-element being designed to seize a loop of thread presented thereto" and to cast the same about said bobbin-carrierash is rotated about s'aid-bobbin-carrier.

2. In a sewing machine, av rotary hook mechanism Comprising a hook frame having an internal circular bobbin-carrier bearing, a bobbin-carrier mounted in said hook frame eccentrically relatively to the axis of said hook frame and having a circularbearing at'the periphery thereof of a diameter less than the diameter of the'bearing of the hook frame by an amount equal to the eccentricity of the bobbin-carrier relatively to the hook frame,

means for holding said bearings radially in engagement at a point of contact to produce between said bearings 'a crescent-shaped gap disposed diametrically opposite from the point of contact and for rotating the'point'of contact and thus the gap between said bearings about thereof of a diameter less than the diameter of thebearing of the hook frame by an amount equal to the eccentricity of the bobbin-carrier relatively to the hook frame, means for supporting said hook frame and providing for rotation thereof relatively to the bobbin-carrier,

means for holding said bearings radially in engagement at a point of contact to produce between said bearings a crescent-shaped gap disposed diametrically opposite from the point of contact and for rotating the point of contact between said bearings about the periphery'of said bobbincarrier, a rotary hook element disposed in the gap, and means for moving said hook-element about said bobbincarrier in unison with'the rotation of the point of contact, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbincarrier. 7

'4. In a sewing machine, a rotary hook mechanism comprising a rotary hook frame having an internal circular bobbin-carrier bearing, means for mounting said hook frame eccentrically relatively to the axis of rotation thereof, a bobbin-carrier mounted in said hook frame in axial alignment with'the axis of rotation of said hook frame and'having a circular bearing at the periphery thereof of a diameter less than the diameter of the bearing of thehook frame by an amount equal tothe eccentricity'of the -hook'frame, means for holding said bobbin carrie r with said bearings radially in engagement at the point of minimum eccentricity of said hook frame producing between said bearings a crescent-shaped gap at the point of maximum eccentricity of said hook frame,

said holding means being rotatable in unison'with the point ofminimum eccentricity of said hook frame, a

rotary hook element disposed' inthe gap, and means 'mounting said hook element for rotation about'the periphery of the bobbin-carrier, said hook element being designed to seize a loop of'thread presented thereto and to cast the same about saidbobbin carrier as it is rotated about said bobbin-carrier. v

5. In a sewing machine, a rotary hook mechanism comprising a rotary hook frame having an internal circular bobbin-carrier bearing, a bobbin-carrier mounted in said 'hook'frame and having a cireularbearing at the peripherylthereof of a diameter less than'the diameter of the bearing of the hookframe, said bearings comprising a bearing rib and a cooperating raceway for receiving said bearing rib,'means for holding said bobbin- "carrier with said bearing rib and'raceway -in' engage-- mentat a point -of contact to produce between'said bearingrib andraceway a crescent-shaped gap disposed diamet-rically opposite from the point of contact and for "-rotating'thepoint of contact about the periphery of said bobbin-carrier, a rotary hook element disposed in the gap, "and m'eans- 'for moving said hook-element about said bobbin-carrier in unison with the rotation of the 'pointof contact, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about" said-bobbin-carrier as it is rotated about said bobbin-carrier.

-6.' In a sewing machine, a rotary hook mechanism comprising a hook frame having an internal bobbinca'rrier bearing -a bobbin-carrier mounted in said hook "frame and having a bearing at the periphery thereof that is smallerthan the bearing of the hook frame, means for supporting the hook'frame and providing for rotation thereofrelativ'ely to the bobbin-carrier, processing means for holding the bobbin-carrier with thebearing thereof -in--engagement-with the bearing of the hook frame at a point of contact to produce between said bearings a crescent-shaped gap disposed diametrically opposite fromthe point of contact and for rotating the point of contact and'thus the gap between said-bearings about the periphery of said bobbin-carrier, a rotary hook-element disposed in the gap, and means formoving said hook-element about said bobbin-carrier in unison with the rotation of said gap, said hook-element being designed toseize a loop of thread presented thereto and to cast th'es same about said bobbin-carrier as itis rotated about said bobbin-carrier.

7. In a sewing machine, a rotary hook mechanism comprising a pair-of hook members consisting of a hook frame and a bobbin-carrier mounted in said hook frame, said hook members having cooperating continuous bearing surfaces one of which is smaller than the other and mountedwithin the other, means for holding said hook 1 members radially in engagement at a point of contact -to produce between said bearings a gap disposed diametrically opposite from the point of contact and for rotating the point of contact and thus the gap between said bearings, a-rotary hook-element disposed in the gap, and means for moving said hook-element in unison with the rotation of said gap, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbin-carrier.

- 8. In a sewing machine, a rotary hook mechanism comprising a rotary hook frame having an internal circular bobbin-carrier bearing, a bobbin-carrier mounted in-said frame eccentrically relatively to the center of said hook frame, and having a circular hearing at the periphery thereof of a diameter less than the diameter ofthe bearing of the hookframe by an amount equal to theeccentricity of the bobbin-carrier relatively to the hook frame, means for supporting the hook frameand providing for-rotation thereof relative to the bobbincarrier, 'precessing means for holding the bobbin-carrier against radial movement with the bearing thereof in en- 0' gagementwith the bearing of the hook frame at a point of contact to-produce between said bearings a crescentshaped gap disposed diametrically opposite. from the point of contact and for rotating the point of contact and'thus the gap between said bearings about the periphery, of said bobbin-carrier, said precessing means comprising a wobble-plate having supporting means including a supporting shaft arranged upon an axis skewed -withmespect to' the axis of said bobbin-carrier, means for rotating said shaft about the axis of said bobbin- 7 carrier wherebysaid wobble-plate will be actuated to project successive portions thereof into cooperation with -said=bobbin-ca'rrier, a rotary hook-element disposed in the gap, and means for moving said hook element about said bobbin-carrier in' unison' -with "the rotation :of. said =7 5 "gap," said hookelement being designed to, I seize a loop "9 of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbincarrier.

9. In a sewing machine, a rotary hook mechanism comprising a rotary hook shaft, a rotary hook frame mounted eccentrically upon said hook shaft for rotation relatively thereto, said hook frame having an internal circular bobbin-carrier bearing, a bobbin-carrier mounted in said hook frame and having a circular hearing at the periphery thereof of a diameter less than the diameter of the bearing of the hook frame by an amount equal to the eccentricity of the hook frame relatively to the axis of the hook shaft, means for holding said bobbincarrier against radial movement away from the point of minimum eccentricity of the hook frame thereby supporting said bobbin-carrier in axial alignment with said hook shaft with the bearing thereof in engagement with the bearing of the hook frame at the point of minimum eccentricity of the hook frame and producing between said bearings a crescent-shaped gap at the point of maximum eccentricity of said hook frame, the action of said bobbin-carrier holding means being rotatable in unison with the rotation of the point of minimum eccentricity of said hook frame for rotating the point of contact between the bobbin-carrier and hook frame and thus the gap about the periphery of said bobbin-carrier, a rotary hook element carried by said hook shaft and disposed in the gap for rotation about said bobbin-carrier in unison with the rotation of the gap, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbin-carrier.

10. A rotary hook mechanism for a sewing machine comprising a rotary hook shaft, hook members comprising a hook frame and a bobbin-carrier each having a cylindrical wall, said hook frame being mounted eccentrically upon said shaft and said bobbin-carrier having an external diameter that is less than the internal diameter of said hook frame by an amount equal to the eccentricity of said hook frame relatively to said shaft, one of said hook members having formed therein a bearing rib and the other of said hook members having formed therein a cooperating raceway, means acting at the point of minimum eccentricity of said hook frame for holding said bobbin-carrier against radial movement away from said hook frame with the raceway receiving said bearing rib, and a rotary hook-element carried by said shaft and disposed within the crescent-shaped gap between the periphery of said bobbin-carrier and the internal surface of said hook frame at the point of maximum eccentricity of said hook frame, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbincarrier.

ll. A rotary hook mechanism for a sewing machine comprising a rotary hook shaft, :1 cup-shaped hook frame eccentrically mounted on said shaft for rotation relatively thereto, said hook frame having a cylindrical side wall terminating at an edge in a plane normal to said shaft, an annular radially-disposed flange extending inwardly from said edge and defining a bearing rib, a cylindrical bobbin-carrier mounted in said frame, said bobbin-carrier having an annular raceway frame upon the external surface thereof that is adapted to receive said bearing rib, the bottom surface of said bearing rib having a diameter that is less than the internal diameter of said bearing rib by an amount equal to the eccentricity of said hook frame relatively to said shaft, :1 concentric ledge formed upon said bobbin-carrier in a plane normal to said shaft, a circular plate mounted upon said shaft for rotation relatively thereto upon an axis inclined to the axis of said shaft, the diameter of the projection of said plate into a plane normal to said shaft being equal to the diameter of said ledge, said plate being so arranged that the extreme portion thereof disposed axially of said shaft toward said bobbin-carrier will be seated on said ledge and the maximum eccentricity of said hook frame being timed diametrically opposite to said extreme portion of said plate whereby said plate will hold said bobbin-carrier against radial movement away from said hook frame with the groove receiving said flange, and a hook-element carried by said shaft and being disposed in the crescent-shaped gap between the periphery of said bobbin-carrier and the internal edge of said flange at the point of maximum eccentricity of said hook frame, said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier as it is rotated about said bobbin-carrier.

12. In a sewing machine, a rotary hook mechanism comprising a pair of hook members consisting of a hook frame and a bobbin-carrier, said hook members having parallel axes and cooperating bearings, one of said bearings being smaller and arranged internally of the other of said bearings, means for restraining said bobbin-carrier against rotation, and means for imparting an epicyclic motion to said hook frame in which the hearing of said hook frame has rolling contact with the bearing of the bobbin-carrier.

13. A rotary hook mechanism for sewing machines comprising a hook frame having a bobbin-carrier hearing, a bobbin-carrier having an external bearing that is smaller than the bearing of said hook frame, means mounting said bobbin-carrier within said hook frame with the hearings in rolling contact and producing a crescent-shaped gap at the point diameterically opposite from the point of contact, and means for rolling said hook frame about said bobbin-carrier with the bearings in cooperation.

14. In a sewing machine, a rotary hook mechanism comprising a hook frame having an internal bobbin-carrier bearing, a bobbin-carrier having an external bearing that is smaller than the bearing of the hook frame, means mounting said bobbin-carier within said hook frame with the hearings in rolling contact, means for restraining said bobbin-carrier against rotation, and means for rolling said hook frame about the bobbincarrier with the bearings in cooperation.

15. In a sewing machine, a rotary hook mechanism comprising a hook frame having an internal circularbobbin-carrier bearing, a bobbin-carrier having an e:'-

ternal circular bearing that is smaller in diameter than the bearing of the hook frame, means mounting said bobbin-carrier within said hook frame with the bearings in rolling contact and for holding said bobbin-carrier with the axis thereof substantially stationary, means for restraining said bobbin-carrier against rotation about its axis, and means for imparting an epicyclic motion to the hook frame in which the bearing of said hook frame has rolling contact with the bearing of the bobbin-carrier.

16. In a sewing machine, a rotary hook mechanism comprising :a pair of hook members consisting of a hook frame and a bobbin-carrier, said hook members having parallel axes and cooperating bearings, one of said bearings being smaller and arranged internally of the other of said bearings, means for restraining said bobbin-carrier against rotation, means for imparting an epicyclic motion to said hook frame in which the bearing of said hook frame has rolling contact with the bearing of the bobbin-carrier, a hook element, and means for supporting said hook-element and for moving the same about said bobbin-carrier in timed relation to the motion of said hook, said hook element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier.

17. A rotary hook mechanism for sewing machines comprising a hook frame having a bobbin-carrier bearing, a bobbin-carrier having an external bearing that is smaller than the bearing of said hook frame, means mounting said bobbin-carrier within said hook frame with the bearings inrolling contact and producing acrescentsaid bobbin-carrier with the bearings in cooperation, a

rotary hook element disposed in the crescent-shaped-gap between said bobbin-carrier and said hook frame, and means for supporting said hook-element and formoving the same about the bobbin-carrier, -said hook-element being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier.

18. In a sewing machine, a rotary hook mechanism comprising a hook frame'having an internaltbobbincarrier bearing, a bobbin-carrier having an external bearing that is smaller than the bearing of the hook frame, means mounting said bobbin-carrier withinsaidhhook frame with the bearings in rolling contact, means for restraining said bobbin-carrier against rotation, means for rolling said hook frame about the bobbin-carrier with the hearings in cooperation, a hook-element, and means for supporting said hook-element and for moving the same about the periphery of the bobbin-carrier in timed relation to the motion of said hook, said hookelernent being designed to seize a loop of thread presented thereto and to cast the same about said bobbin-carrier.

1-9. Ina sewing-machine, a rotary' hook mechanism -'comprisinga hook -f11ame having an internal circular bobbin-carrier bearing, a bobbin-carrier having an external -circular=bearing that is smallervin diameter than "the bearing of the hook frame, means mounting said bobbin-carrierwithin said hook frame with the hearings in rolling contact and for holding said bobbin-carrier with the axisthereof substantially stationary, means for restraining said bobbin-carrier against rotation about its waxis,.-means for imparting an epicyclic motion to the hook frame in which the bearing of said hook frame has rolling contact with-the bearing .of the bobbin-carrier, a

hook element, and means: for supporting said hook-element and formoving the same about said bobbin-carrier in timed relation to the: motion "of said hook, said hookelement being designeduto seize-a loop of thread presented thereto and to cast the same about said bobbincarrier.

-Ref eren ces Cited in; the ,file of this patent UNITED STATES PATENTS 1,049,791 Winkel Jan. 7, 1913 2,246,010 .Rubel June 17, 1954

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