US3087447A - Round-bobbin case for sewing machines - Google Patents

Description

April 30, 1963 H. ADAM ROUND-BOBBIN CASE FOR SEWING MACHINES Filed Oct. 10, 1960 2 Sheets-Shes April 30, 1963 H. ADAM 3,087,447

ROUND-BOBBIN CASE FOR SEWING MACHINES Filed Oct. 10, 1960 2 Sheets-Sheet 2 United States Patent Ofitice Patented Apr. 36, 1953 ROUND-BGBBEN CASE FOR SEWENG MACHINES Hermann Adam, Bielefeld, Germany, assignor to Anker- Phoenix Nahmaschinen AG, Bielefeld, Germany, a

German corporation Filed (Pct. 1t 1960, Ser. No. 61,630 Claims priority, application Germany Get. 12, 1959 6 Claims. (Cl. 112-231) My invention relates to a round-bobbin case for sewing machines of the rotary loop-taker (rotary hook) type and particularly to round-bobbin cases for ring-shaped loop-takers having a horizontal axis of rotation.

In the known bobbin cases of this type, one of the stop lugs or fingers of the case which abuts against a stationary stop of the machine structure for preventing the bobbin case from rotating while the loop-taker hook is in operation, is provided with an eye through which the yarn coming from the bobbin in the casing passes to the material being sewed. Threading the yarn through the small eye is inconvenient as it requires some time and good eyesight of the seamstress.

In sewing machines of diiicrent kind, such as roundbobbin machines with a loop-taker hook oscillating about a vertical axis, it is known to provide the bobbin case with a slot through which the yarn passes from the bobbin case with a slot through which the yarn passes from the bobbin to the sewing material, and which facilitates threading of the yarn when inserting a full bobbin. Such slots are also being provided in some machines of other types. Among these is a machine with a rotary hook which performs two revolutions for each stitch, a bobbin casing and a carrier for the casing are telescopically joined with each other and received within a loop-taker member in which they are kept by a latch member in the proper position. The carrier of the bobbin casing is provided with stop means cooperating with stationary abutrnents of the machine base to prevent rotation of the carrier. A finger of the bobbin housing enters between the lugs of the bobbin-case carrier, and this finger possesses a slot for guiding the yarn. The finger carries on its outer side a guiding spring which, together with the upper portion of the slot, forms an upwardly open yarn guiding eye through which the under thread can pass to the sewing material.

However, it is not readily possible to provide the holding finger with a guiding slot for the under thread in a bobbin casing for ring-shaped loop-taker hooks that rotate about a horizontal axis. This is because the under thread passes out of the eye in a radial direction and hence transversely to the rotation axis of the loop-taker hook. Furthermore, the necessity for light-weight and the limited space available for the bobbin casing in such horizontal-axis ring-shaped loop-taker devices make it necessary to give the stop lug for the bobbin case a relatively small wall thickness in the direction transverse to the longitudinal axis of the loop-taker member. This does not permit replacing the above-mentioned known yarn-guiding eye by a slot extending in the same direction.

It is an object of my invention to solve this problem and to devise a round-bobbin case for rotary loop-taker devices of the horizontal-axis type, that facilitates threading the bobbin yarn through the casing, thus reducing the necessary threading time as well as the requirements as .to skill or eyesight of the seamstress.

To this end, and in accordance with my invention, I

give the stop lug or finger of the bobbin case a generally hook-shape design so located that, when the casing is in operative position, the bight of the hook is at the top and the two legs of the hook extend downwardly, one being integral with the bobbin case proper Whereas the other is somewhat spaced from the main body of the casing in order to form a generally V-shaped slot of which one portion extends up into the bight of the hook. The width or thickness of the material forming the V-shaped slot in such a device extends parallel to the rotation axis of the bobbin case.

The foregoing and further features of my invention will be more fully described in the following with reference to the embodiment of a bobbin case according to the invention illustrated by way of example on the accompanying drawings in which:

FIGS. 1, 2 and 3 show the bobbin case in plan view, top view and partly sectional side view respectively.

FiG. 4 is a vertical section on the center axis of FIG. 1 and also shows a bobbin inserted.

FIG. 5 is a perspective view from the rear of the casing and an inserted bobbin.

FIGS. 6 and 7 show the bobbin case in a view similar to FIG. 1, but in respectively diiferent stages of an under thread being threaded into, and guided by, the slot in a hook-shaped lug of the casing.

FIGS. 8, 9 and 10 relate to the manufacture of the bobbin casing and show the casing incomplete in plan view and two vertical sections respectively.

FIGS. 11a, b, c jointly show an exploded perspective view of the loop-taker, bobbin-case and cover assembly.

The illustrated bobbin case 1 for a rotary loop-taker forms a circular flange 2 which, when the case is in operative position, is guided in a ring-shaped guiding groove 31 (FIG. 4) of the rotating loop-taker (hook) body 32. In this position, the case 1 is prevented from rotating relative to the loop-taker, by means of a nose 33 of a ring-shaped cover 35 (FIG. llc) fixed in the sewing machine structure. The nose 3-3 enters between holding lugs or fingers 3 and 4 of the case 1. The guiding groove 31 of the loop-taker body 32 defines the position of the case 1 with respect to all radial directions as well as relative to one axial direction. In the other axial direction, the case is kept in proper position by a nose 33 of a ringshaped cover 35 (FIG. for the loop-taker 32. The bobbin 5 is rotatable about a horizontal axis within the cup space 7 of the case 1 FIGS. 4, 5).

When a new bobbin is being inserted into the case, the under thread 10 coming from the bobbin is first passed through a slot 8 (FIG. 5) in the wall of the casing. From slot 8, the under thread is passed beneath a tension spring 9 and is then pulled in axial direction through the portion 11 of a thread-supplying or V-shaped slot (FIG. 6). Thereafter, the seamstress moves the under thread in radial direction until it is placed against the bottom 15 of a vertical slot portion 12. While inserting the bobbin case 1 into the loop-taker member 32, the under thread is slightly pulled upwardly by the seamstress. This causes the thread to pass from the bottom 15 of the threadguiding slot 12 up to a thread-guiding edge 14 (FIG. 3) formed in the top portion of the slot 12.

In order to prevent the thread, during the vertical upward displacement just described, from being caught by the tip 16 (FIG. 6) formed by the generally V-shaped arrangement of the two slot portions 11 and 12, and from being thus inadvertently diverted back into the slot portion 11, the tip 16 is somewhat set back from the right-hand side of the slot portion 12. To prevent that the upper (needle) thread 17 (FIG. 1), which during loop or lock-stitch formation glides along the planar front face 13 of the case upwardly, is not inadvertently caught by the tip 16, the tip is flush with the planar front face 13 of the case 1 and has rounded edges.

For improved uniformity of the knots formed by upper thread and under thread in the sewing material, the bob bin 5 (FIGS. 4, 5) is journalled in the cup space 7 of the case 1 at the outer periphery of the bobbin. The slight friction at the periphery then prevents the bobbin from performing an undesired leading rotary travel relative to the case when the bobbin is full and hence has relatively great inertia, and has also the effect that during each cycle of stitch formation the bobbin is turned only a given desired amount. As a consequence, the pull of the thread during rotation of the bobbin remains sub stantially uniform.

The front side 13 of the case 1 is provided with a relatively large central opening 18. The resulting reduction in weight and inertia has a favorable effect upon the stitch knotting operation. To secure an easy and uniform pull-oif of the upper-thread loop 17 (FIG. 1) from the bobbin case 1, the transition radius 19 from the front face 13-to the conical portion 20 of the bobbin case is made so large that the center point of the radius 19 is located substantially in the plane of the guiding edge 2 (FIG. 2).

It will be apparent from the foregoing that the stop lug 3 in a bobbin case according to the invention has generally the shape of an inverted U whose one leg is integral with the material of the casing wall 13 that forms the bottom of the cup space, whereas the other leg of the U-shape extends downwardly and terminates at some distance away from the wall structure of the casing so as to form the above-mentioned slot portion 11 which together with the space between the U-legs forms the above-mentioned V-shaped slot. This slot extends toward the center axis of the bobbin case a sufficient distance to occupy part of the cup-space bottom (FIG. 3). The guiding edge 14 in the bight of the U-shaped hook member or lug 3 is inclined in an upward direction from the open side of the cup space toward the opposite side.

The case 1 can readily be produced from sheet metal by drawing, this operation being facilitated by the provision of the large opening 18. The manufacture is preferably such that first a cup 21 (FIG. 9) is drawn which is to constitute the front portion 13, the conical peripheral portion 20 and the guide-way portion 2 of the case. Thereafter a lug 22 is cut and bent out of the cup structure 21 (FIGS. 8, 9), and the ultimate stop lugs 3 and 4 are then machined or stamped out of the material at 22. The inner cylindrical portion 23 (FIG. of the casing is thereafter welded together with the outer cup structure 21 to form the cup space for receiving the bobbin 5. According to FIG. 8, the right side 24 of the lug 22 is cut on a slant. As a result, the right hand side 25 (FIG. 1) of the ultimate stop lug 4 possesses the same slanting shape. The inclination of this slant is such that, during stitch knotting operation, the upper (needle) thread 17 (FIG. 1) can be pulled off the bobbin case along the inclined edge 25 of lug 4 without encountering resistance.

I claim:

1. Round-bobbin case for rotary loop-taker in sewing machines, comprising a generally cylindrical case structure having a cup space adapted to hold a bobbin for rotation about a horizontal axis when in operation, two stop lugs extending upwardly away from said cup space and being peripherally spaced from each other to prevent rotation of said structure, one of said two lugs forming a hook of inverted U-shape which has its two U-legs extending from the U-bight downwardly, the one leg remote fro-m said other lug being integral with said structure, the other leg terminating in spaced relation to said structure and forming together therewith a V-shaped slot, whereby the slot portion between said two lugs permits threading of the bobbin yarn through the casing and the slot portion between the U-legs serves to guide the yarn from the bobbin to the sewing material.

2. Round-bobbin case for rotary loop-taker sewing machines, comprising a generally cylindrical case structure having a cup space adapted to hold a bobbin for rotation about a horizontal axis when in operation, two stop lugs extending upwardly away from said cup space and being peripherally spaced from each other to prevent rotation of said structure, one of said two lugs forming a bight of inverted U-shaped with a vertical threadguiding slot therebetween and which has its two U-legs extending from the U-bight downwardly to for-m a slot portion between said U-legs for guiding the yarn from the bobbin to material being sewed, the leg closest to the other of said two lugs terminating in spaced relation to said structure and forming together therewith a V-sh-aped thread-insertion slot between the two lugs and joining said vertical slot for permitting threading the bobbin yarn through said case structure, said other lug being closely adjacent said V-shaped slot and shaped for deflecting an upper thread lo'op passing thereover away from" said V- shaped slot so as to prevent said thread loop from being caught or severed in the latter, said case structure comprising :a substantially frustoconical peripheral portion extending around said cup space and having a circular edge for engaging the loop-taker, said two lugs and said peripheral portion consisting of a single integral piece of material, and said lugs forming cut-outs of said peripheral portion and extending parallel to the plane of said cup .space.

3. Round-bobbin case for rotary loop-taker sewing machines, comprising a generally cylindrical case structure having a cup space adapted to hold a bobbin for rotation about a horizontal axis when in operation, two stop lugs extending upwardly away from said cup space and being peripherally spaced from each other to prevent rotation of said structure, one of said two lugs forming a book of inverted U-shape which has its two U-legs extend from the U-bight downwardly, the one leg remote from said other lug being integral with said structure, the other leg terminating in spaced relation to said structure and forming together therewith a V-shaped slot, whereby the slot portion between said two lugs permits threading of the bobbin yarn through the casing and the slot portion between the U-legs serves to guide the yarn from the bobbin to the sewing material, said V-shaped slot being in a radial plane relative to said axis and having a yamguiding surface extending in said bight of said stop lug in 'a direction upwardly inclined from the cup side to the opposite side of the lug.

4. A round-bobbin case according to claim 2, said U-leg closest to said other lug tapering in the direction of said insertion slot so as to enlarge the lower portion of said vertical slot at its juncture with said thread-insertion slot in the direction of the central axis of said case structure, said two lugs both being laterally set back toward said cup space from the plane defined by the casing surface beneath said cup space.

5. Round-bobbin case for rotary loop-taker sewing m-achines, comprising a generally cylindrical case structure having a horizontal axis when in operative position and forming a cup-shaped bobbin container for holding a bobbin rotationally about said axis, stop lug means provided with a thread-guiding slot lying in a plane perpendicular to said horizontal axis, means forming a thread-supplying slot for introducing an upper thread and extending inwardly and inclined from the outer edge of said case structure to intersect said thread-guiding slot at an acute angle, said stop lug means further comprising a loopguiding member positioned near said thread-supplying slot and shaped to extend across a line forming the extension of the axis of said thread-supplying slot for shielding the latter, said case structure forming a slitted outlet opening spaced from said thread-supplying slot for passing a lower thread downwardly from said bobbin, and

thread-tension regulating spring means arranged on said structure partially covering said slitted outlet opening.

6. Bobbin case according to claim 5, said case structure including said stop lug means and said thread-supplying and thread-guiding slots all consisting of a single stamping and being integral with said bobbin container, and means forming a central opening in said case structure for reducing the weight thereof.

References Cited in the file of this patent UNITED STATES PATENTS Flanagan May 8, 1906 Francis Dec. 2, 1919 Ayres Jan. 17, 1956 Howard Sept. 18, 1956

Claims (1)

1. ROUND-BOBBIN CASE FOR ROTARY LOOP-TAKER IN SEWING MACHINES, COMPRISING A GENERALLY CYLINDRICAL CASE STRUCTURE HAVING A CUP SPACE ADAPTED TO HOLD A BOBBIN FOR ROTATION ABOUT A HORIZONTAL AXIS WHEN IN OPERATION, TWO STOP LUGS EXTENDING UPWARDLY AWAY FROM SAID CUP SPACE AND BEING PERIPHERALLY SPACED FROM EACH OTHER TO PREVENT ROTATION OF SAID STRUCTURE, ONE OF SAID TWO LUGS FORMING A HOOK OF INVERTED U-SHAPE WHICH HAS ITS TWO U-LEGS EXTENDING FROM THE U-BIGHT DOWNWARDLY, THE ONE LEG REMOTE FROM SAID OTHER LUG BEING INTEGRAL WITH SAID STRUCTURE, THE OTHER LEG TERMINATING IN SPACED RELATION TO SAID STRUCTURE AND FORMING TOGETHER THEREWITH A V-SHAPED SLOT, WHEREBY THE SLOT PORTION BETWEEN SAID TWO LUGS PERMITS THREADING OF THE BOBBIN YARN THROUGH THE CASING AND THE SLOT PORTION BETWEEN THE U-LEGS SERVES TO GUIDE THE YARN FROM THE BOBBIN TO THE SEWING MATERIAL.

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