ROTARY SHUTTLE DEVICE AUGMENTED UNDER THREAD CAPACITY FOR SEWING MACHINE

WIPO Patent Application WO/2005/087998

A1

The present invention relates to a rotary shuttle device augmented an under thread capacity for a sewing machine, in which an air track is formed at a tongue of a bobbin case base so as to be capable of increasing a length and diameter of the bobbin case base and also a receiving space without an increase in frictional resistance, thereby remarkably increasing a winding amount of under thread wound on a bobbin and thus remarkably improving productivity and a swing quality of a high-class sewn product. To this end, the rotary shuttle device augmented an under thread capacity for a sewing machine, comprising a hook body (20) disposed at a driving shaft (10) and having a track groove (21) at an inner circumferential surface; a bobbin case BC provided with a bobbin case base 300 accommodated in the hook body (20) and having a tongue (320) at an outer circumferential side so as to be slidably inserted into the track groove (21) of the hook body, and a bobbin case body (50) for holding a bobbin at an outside; and a bobbin (40) disposed in the bobbin case BC and on which under thread is wound, is characterized in that the tongue (320) of the bobbin case base is formed an air track (323).

Lee, Sang Cheol (Officetel 2214, Woosungcharacter 199 Dogok2dong 467-2, Kangnam-gu Seoul 135-270, KR)

PCT/KR2005/000408

September 22, 2005

February 15, 2005

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KOBEST CO., LTD. (Officetel 2214, Woosungcharacter 199 Dogok2dong 467-2, Kangnam-gu Seoul 135-270, KR)
Lee, Sang Cheol (Officetel 2214, Woosungcharacter 199 Dogok2dong 467-2, Kangnam-gu Seoul 135-270, KR)

D05B57/28; D05B57/26; D05B57/00; (IPC1-7): D05B57/28

Bae, Yong Cheol (100-305, Bucheon Techno-Park 364 Samjung-dong, Ojung-g, Bucheon- City Kyunggi-do 421-740, KR)

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Description [1] ROTARY SHUTTLE DEVICE AUGMENTED UNDER THREAD CAPACITY FOR SEWING MACHINE [2] TECHNICAL FIELD [3] The present invention relates to a rotary shuttle device for a sewing machine, and more particularly, to a rotary shuttle device augmented an under thread capacity for a sewing machine, in which an air track is formed at a tongue of a bobbin case base so as to be capable of increasing a length and diameter of the bobbin case base and also a receiving space without an increase in frictional resistance, thereby remarkably increasing a winding amount of under thread wound on a bobbin and thus remarkably improving productivity and a swing quality of a high-class sewn product. [4] BACKGROUND ART [5] Generally, in the sewing machine, there is provided a rotary shuttle device 100 for supplying the under thread. The rotary shuttle device 100 is disposed at a driving shaft 10 which is rotatably connected to a driving apparatus, and comprised of a hook body 20, a bobbin case BC accommodated in the hook body 20 and a bobbin 40 on which the under thread is wound. The bobbin case BC comprises a bobbin case base 30 ac¬ commodated in the hook body 20 and a bobbin case body 50 for receiving the bobbin 40 from an outside of the bobbin 40. [6] At a bottom of the bobbin case base 30, there is upright disposed a stud 31. The bobbin 40 is rotatably disposed at the stud 31. A track groove 21 is formed in an inner side of the hook body 20. A hook 22 is formed at an end of the hook body 20. In the vicinity of the hook 22, there is formed a groove 23 having a gentle radius of curvature so that the under thread is passed through the groove 23, while being contacted with the groove 23. On an outer side of the bobbin case base 30 is formed a tongue 32 as a track portion which is inserted into the track groove 21 of the hook body 20 so that the bobbin case base 30 is disposed in the hook body 20 and the hook body 20 is also capable of being rotated. [7] Meanwhile, a semicircular gib 25 is fixed to one half portion of an outside portion of the hook body 20 by fastening means such as a bolt so that the bobbin case base 30 can be rotatably disposed and the bobbin case base 30 can be inserted therein or separated therefrom. The gib 25 has a hook 25a opposite to the hook 22 formed at the hook body 20. Further, a thread guide 26 is removably fixed to the other half portion of the outside portion of the hook body 20 by the fastening means such as the bolt so as to be continuous with the gib 25. The thread guide 26 also has a hook 26a opposite to the hook 25a of the gib 25. [8] The bobbin case base (hereinafter, called base) 30 and the bobbin case body (hereinafter, called body) 20 provided with a latch 51 are integrally coupled to each other to form the bobbin case BC. A bracket (not shown) which is adjacent to the bobbin case BC and disposed at a body of the sewing machine is inserted into a concaved portion 33 formed at the base 30 so as to position the bobbin case BC, so that the bobbin case BC is fixedly positioned. Furthermore, in the vicinity of the concaved portion 33, there is formed a through-hole 34 through which a sewing needle is passed when the needle is moved down. [9] The bobbin 40 comprises a winding shaft 41 on which the under thread is wound, a first flange 43 formed at one end of the winding shaft 41 and a second flange 45 formed at the other end of the winding shaft 41. [10] Now, an operation of the rotary shuttle device as described above will be described below. [11] When the sewing machined is operated, the hook body 20 is rotated, and at the same time, a thread take-up lever (not shown) of upper thread and the needle are moved up and down. During two revolutions of the hook body, the needle hooks up the under thread once. Due to a thread taking-up operation, a desired length of thread is pulled so as to prepare for a next under thread hooking-up operation. [12] FIG. 2 is a view in which the bobbin case BC and the bobbin 40 are omitted so as to show a status that the upper thread 3 threaded through the needle 2 is hooked on the hook body 20 when the needle 2 is moved down, FIG. 3 is a view showing a moment that the upper thread is hooked by the hook body 20, and FIG. 4 is a side view of FIG. 3. [13] Furthermore, FIGs 5 to 10 show in turn a sewing operation, and a), b), c), d), e) and f) of each drawings are views from a front of the rotary shuttle device, and a'), b'), c'), d'), e') and f ) are views showing a status that the hook body 10 is reversed so that a bottom of the hook body 20 is directed upward to help the understanding. [14] If the sewing machine is operated, the needle through which the upper thread 3 is threaded is moved down. At the same time, the upper thread is hooked down by the hook 22, while the hook body 20 is rotated with a descent of the needle (referring to FIGs. 2, 5 and 6). Since a slit 2a is formed at a side of the needle 2 so that the upper thread threaded through the needle can be hooked down by the hook 22 of the hook body 20, the above operation can be performed. At this time, if a distance between the needle 2 and the hook 22 is far away, since the upper thread 3 is not hooked onto the hook 22, a sewn line is omitted at times or a sewing operation is not normally performed. If the distance is too close, since the needle is collided with the hook 22, the needle is broken. [15] As described above, the upper thread 3 hooked down by the hook 22 of the hook body 20 is guided by the thread guide 26 of the hook body 20 so as to form a loop for wrapping the bobbin case BC, thereby hooking up the under thread 4 (FIGs. 7 to 10). As described above, the reason why the upper thread 3 can warp the bobbin case BC and form the loop is because the upper thread 3 is previously pulled by the thread take- up lever in the previous stroke. [16] The length of upper thread pulled by the thread take-up lever, while the thread take- up lever is reciprocated once, is coincident with a length of the upper thread required to wrap the bobbin case BC while the hook body 20 makes one revolution. If a volume of the hook body 20 closely related with a volume of the under thread is increased, the length of the upper thread pulled by the thread take-up lever is short so that the thread is broken, and tension balance between the under thread and the upper thread is also broken, whereby the under thread sewn to a very thin cloth is dangled down and fluttered roughly on the sewn line. [17] If a winding amount of the under thread is increased, the number of replacing operations of the bobbin can be reduced, thereby increasing productivity. However, if a size of the bobbin case is increased according to the increase in the winding amount of the under thread, since the length of the upper thread pulled by the thread take-up lever is limited, the length of the upper thread is not enough to wrap the bobbin case. In other words, since the loop of the upper thread having the short length cannot wrap the bobbin case BC, the upper thread is broken. The only answer to solve the problem is that a length of the thread take-up lever is increased. However, since a basic con¬ struction of the sewing machine, which is globally compatible, has to be changed, it is actually impossible. [18] As shown in FIG. 11, the base 30 is provided with a tongue 32 protruded from a main wall 35 thereof and functioning as an inflective guide when the upper thread is stripped off. Since lubricating oil is sprayed between the tongue 32 and the hook body so that the hook body 20 can be smoothly rotated and sludge dust of the thread is generated, the tongue 32 is formed with one or more through-hole 32b for venting air and sucking the sludge. [19] In the construction as described above, the tension of the under thread is applied to a stripping sector £ from an under portion of the tongue 32 to a bottom surface 37. In a case that a length of the stripping sector I is extended in order to expand a receiving space of the base, and an entire length L2 of the base is thus extended, a thread breakage is occurred. [20] That is, a portion in which maximum tension is applied to the upper thread while the loop of the upper thread becomes wider towards both sides of the base 30 (FIG. 9) and the body 50 by the thread guide 26 of the hook body 20 (FIG. 8) is the stripping sector I from the under portion of the tongue 32 to the bottom surface 37. [21] Meanwhile, the applicant perceives that, if a width of the tongue 32 of the base 30 is expanded and the time of stripping off the under thread is advanced, a problem of the thread breakage is avoided and the entire length L2 of the base 30 is extended as much as the expanded size and a winding amount of the under thread wound on the bobbin 50 can be also increased. [22] However, since the tongue 32 is inserted into the track groove 21 formed in the hook body 20 and the friction is thus happened when the hook body is rotated, if a frictional surface area is increased, frictional resistance is also increased. Therefore, there is a problem that an intense heat is generated, and the thread is burned up. [23] DISCLOSURE OF THE INVENTION [24] Therefore, an object of the present invention is to provide a rotary shuttle device augmented an under thread capacity for a sewing machine, in which an air track is formed at a tongue of a bobbin case base so as to be capable of increasing a length and diameter of the bobbin case base and also a receiving space without an increase in frictional resistance, thereby remarkably increasing a winding amount of under thread wound on a bobbin and thus remarkably improving productivity and a swing quality of a high-class sewn product. [25] According to the present invention, a rotary shuttle device augmented an under thread capacity for a sewing machine, comprising a hook body disposed at a driving shaft and having a track groove at an inner circumferential surface; a bobbin case BC provided with a bobbin case base accommodated in the hook body and having a tongue at an outer circumferential side so as to be slidably inserted into the track groove of the hook body, and a bobbin case body for holding a bobbin at an outside; and a bobbin disposed in the bobbin case BC and on which under thread is wound, is characterized in that the tongue of the bobbin case base is formed an air track. [26] BRIEF DESCRIPTION OF DRAWINGS [27] FIG. 1 is an exploded perspective view of a conventional rotary shuttle device for a sewing machine; [28] FIG. 2 is a view showing a status that upper thread threaded through a needle is hooked on a hook body when the needle is moved down; [29] FIG. 3 is a view showing a moment that the upper thread is hooked by the hook body; [30] FIG. 4 is a side view of FIG. 3; [31] FIGs. 5 to 10 are views showing sewing processes; [32] FIG. 11 is an elevation view of an example of a conventional bobbin case base; [33] FIG. 12 is an exploded perspective view of a rotary shuttle device for a sewing machine according to an embodiment of the present invention; [34] FIG. 13 is an elevation view of a bobbin case base according to the embodiment of the present invention; [35] FIGs. 14 to 17 are views showing only tongue portion of bobbin case base, in which the tongue portion is spread, according to various embodiments of the present invention; and [36] FIGs. 18 to 21 are cross-sectional views showing a part of the tongue of the bobbin case base according to the present invention. [37] BEST MODE FOR CARRYING OUT THE INVENTION [38] The present invention will now be described in further detail by examples. It would be obvious to those skilled in the art that these examples are intended to be more concretely illustrative and the scope of the present invention as set forth in the appended claims is not limited to or by the examples. [39] FIG. 12 is an exploded perspective view of a rotary shuttle device for a sewing machine according to an embodiment of the present invention, and FIG. 13 is an elevation view of a bobbin case base of FIG. 12. [40] As shown in FIGs. 12 and 13, a rotary shuttle device 1 augmented an under thread capacity for a sewing machine according to an embodiment of the present invention comprises a hook body 20 disposed at a driving shaft 10 and having a track groove 21 at an inner circumferential surface; a bobbin case BC provided with a bobbin case base 300 accommodated in the hook body 20 and having a tongue 320 at an outer circum¬ ferential side so as to be slidably inserted into the track groove 21 of the hook body, and a bobbin case body 50 for holding a bobbin at an outside; and a bobbin 40 disposed in the bobbin case BC and on which under thread is wound. [41] In the tongue of the bobbin case base 300, there is formed an air track 323. [42] A starting portion 325 of the tongue 320 is formed to be inclined at an inflection angle θ for guiding the stripping of the upper thread. [43] At the tongue 320, there is formed one or more through-hole 327 for passing lu¬ bricating oil and collecting sludge generated from the thread 431. [44] The tongue 320 has an expanded width B in which a width b of the air track 323 is added to an existing width of the tongue 320. [45] It is natural that a width of the track groove 21 of the hook body 20, in which the tongue is inserted to be slid, should be expanded to be corresponding to the expanded width B of the tongue 320 and an entire depth of the hook body 20 should be also expanded. [46] Preferably, the air track 323 is elongatedly formed along an outer circumferential surface of the tongue 320 in a center portion thereof. FIGs. 14 to 17 are views of the tongue 320 which is spread. [47] As shown in FIG. 14, it is preferred that the air track 323 be continuously and elongatedly formed from a portion after the through-hole 327. However, as shown in FIGs. 15 and 16, the air track 323 may be intermittently and repeatedly formed along the outer circumferential surface of the tongue 320. Further, as shown in FIG. 17, a plurality of air tracks 323 may also formed in parallel. [48] As shown in FIGs. 18 to 21, the air track 323 may have various depressed sections such as a ">" shape, a "D" shape, a semicircular shape, a "D" shape, etc. [49] In addition, the width b of the air track 323 may be formed to have a length of about lmm. A reference numeral 310 is a stud, 350 is a mail wall, and 370 is a bottom surface. [50] An operating state of the rotary shuttle device 1 for a sewing machine, as described above, will be described in detail. [51] According to the present invention, since the air track 323 is formed in the tongue 320, the width B of the tongue 320 can be expanded without an increase in a frictional surface area with the hook body 20. [52] Therefore, the width B of the tongue 320 can be expanded while excluding frictional resistance, and an entire length Ll of the bobbin case base includes an increment of the width of the tongue 320. Thus, a receiving space of the bobbin case BC can be expanded. [53] In other words, a length of a stripping sector £ from a lower side of the tongue 320 to the bottom surface 370 is the same as an existing length thereof. The width b of the air track 323 formed in the tongue 320 is added to an existing length L2 of the bobbin case base 300 so that an entire length Ll of the bobbin case base 300 can be expanded so as to increase a receiving capacity. Therefore, a winding length and diameter of the bobbin 50 received in the bobbin case base 300 can be also expanded, thereby increasing a winding amount of the under thread. [54] Meanwhile, if only the length Ll of the bobbin case base 300 is extended, the upper thread formed into a loop shape with a limited length will be broken. [55] Therefore, in order to prevent the upper thread breakage, the inclined portion is formed on the starting portion 325 of the tongue 320 at the inflection angle θ. [56] It is possible to form the inflection angle θ by expanding the width of the tongue 320. The inclined portion functions to shorten a stripping length of the under thread and thus advance the time of stripping off the upper thread at the stripping sector. Therefore, although the entire length of the bobbin case BC is increased, the thread breakage can be prevented. [57] By advancing the time of stripping off the upper thread using the construction of the inflection angle θ, it is possible to expand the diameter D of the bobbin case base 300 as well as the length Ll of the bobbin case base 300. The expansion of the diameter D is realized within an extent that a size c of the tongue 320 protruded from the main wall 350. [58] The width B of the tongue 320 and theinflection angle θ for stripping off the upper thread 3 are designed so as to satisfy two conditions that the tension of the upper thread should be properly maintained and the upper thread breakage should be prevented. [59] The winding amount of the upper thread increased by the expansion of the length Ll and the diameter D of the bobbin case base 300 comes up to about 130 ~ 150%. [60] On the other hand, since the upper thread is smoothly stripped from the bobbin case base and the tension of the upper thread is also properly maintained, it is possible to obtain a good sewing quality even in the sewing operation of very thin cloth. [61] According to the present invention, since the air track 323 is formed in the tongue 320 of the bobbin case base 300, it is possible to increase the width of the tongue, the length Ll and diameter D and the inner receiving space of the bobbin case without any increase in the frictional resistance. Furthermore, since the winding length and diameter of the bobbin received in the inner receiving space of the bobbin case is also expanded, and the tension of the upper thread is properly maintained, the winding amount of the under thread wound on the bobbin is remarkably increased, thereby increasing productivity of a sewing operation and obtaining excellent sewing quality in a sewing operation of thin cloth. [62] While the present invention has been described in detail, it should be understood that various changes, substitutions and alterations could be made hereto without departing from the spirit and scope of the invention as defined by the appended claims. [63] INDUSTRIAL APPLICABILITY [64] In the rotary shuttle device for a sewing machine according to the present invention, as described above, since the air track is formed in the tongue of the bobbin case base, it is possible to increase the width of the tongue, the length and diameter and the inner receiving space of the bobbin case without any increase in the frictional resistance. Thus, since the winding length and diameter of the bobbin received in the inner receiving space of the bobbin case is also expanded, the winding amount of the under thread wound on the bobbin is remarkably increased, thereby increasing productivity of a sewing operation and obtaining excellent sewing quality.

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