A CHANGEABLE SEWING MACHINE SHUTTLE

Technical Field The present invention relates, in general, to changeable shuttles for sewing machines and, in detail, to shuttles which hold bobbins, around which lower threads are wound, in sewing machines used for sewing fabric, such as clothes, and, particularly, to a changeable shuttle for sewing machines of which a part, on which friction is generated due to contact of inner and outer shuttles during their rotation, can be replaced with a new one.

Background Art Generally, sewing machines execute sewing processes using upper and lower threads. An upper thread is directly connected to a needle of a sewing machine to be stitched on a surface of a desired material (fabric) . A lower thread is provided in a shuttle below the material being sewn. The lower thread is used for preventing the upper thread from being loosened while being stitched. The lower thread is provided in the shuttle which is installed in a lower part of the sewing machine, and it is stitched by the needle. Conventional shuttles, which provide lower threads to sewing machines, include inner shuttles and outer shuttles. Bobbins, around which the lower threads are wound, are mounted to the inner shuttles. In the above-mentioned conventional shuttles, as shown in FIG. 1, an outer shuttle 110 has a shaft hole 111 on the center thereof to be coupled to a rotating shaft 112 by a locking bolt. An inner shuttle 120 is rotatably inserted into the outer shuttle 110. A bearing rib 122 is provided on an outer surface of a main body 121 of the inner shuttle 120. A flange part 124 having a rotating stopper groove 123 is provided at a predetermined position on an open side of the inner shuttle 120. A stud 125 protrudes from the center of the other side of the inner shuttle 120 towards the open side of the inner shuttle 120. The outer shuttle 110 has a slide groove 113 on an inner surface thereof, so that the bearing rib 122 formed on the outer surface of the main body 121 of the inner shuttle 120 rotatably engages with the slide groove 113. Due to the engagement of the slide groove 113 and the bearing rib 122, the inner shuttle 120 is rotatably coupled to the outer shuttle 110 without being undesirably removed from the outer shuttle 110. Furthermore, the outer shuttle 110 has inner and outer covers 114 and 115 and a cap 116 for changes in direction and location of upper and lower threads during a sewing process. The outer shuttle 110 is rotated by the rotation of the rotating shaft 112. The inner shuttle 120 rotates in the outer shuttle 110 while the bearing rib 122 of the inner shuttle 120 engages with the slide groove 113 of the outer shuttle 110. A bobbin (not shown), around which the lower thread is wound, is mounted to the stud 125 of the inner shuttle 120 for supply of the lower thread. The outer shuttle 110 and the inner shuttle 120 are formed into a single body. That is, the slide groove 113 of the outer shuttle 110 and the bearing rib 122 of the inner shuttle 120 are integrated to form a single body. Such shuttles for sewing machines are expendables requiring periodic replacement. In other words, because the slide groove 113 of the outer shuttle 110 is in surface contact with the bearing rib 122 of the inner shuttle 120 while the inner and outer shuttles 110 and 120 are rotated by the rotating shaft 112, abrasion due to friction occurring during their rotation is generated. Therefore, a gap develops between the slide groove 113 and the bearing rib 122 due to use over a long period. Due to the gap, the shuttle vibrates. As a result, it leads to poor sewing quality. Therefore, to prevent such problems, periodic replacement of the shuttle is required. However, in conventional shuttles for sewing machines, the slide groove of the outer shuttle and the bearing rib of the inner shuttle are integrated. Therefore, when replacement of the worn shuttle is desired, because worn parts alone cannot be replaced, the whole inner and outer shuttles must be replaced with new ones. This is very inefficient expensive. Furthermore, it reduces the life span of the whole shuttle. As such, the conventional shuttles are non-economical.

Description of Drawings FIG. 1 is an exploded perspective view showing a conventional shuttle for sewing machines; FIG. 2 is an exploded perspective view of a changeable shuttle for sewing machines, according to the present invention; FIG. 3 is a perspective view of the changeable shuttle for sewing machines, according to the present invention; FIG. 4 is a sectional view of the changeable shuttle for sewing machines, according to the present invention; FIG. 5 is a perspective view showing an enlargement of an important part of the changeable shuttle for sewing machines, according to the present invention; FIG. 6 is a perspective view showing an enlargement of another important part of the changeable shuttle for sewing machines, according to the present invention; FIG. 7 is an enlarged sectional view of a circled portion 'A' of FIG. 4; and FIG. 8 is an exploded perspective view of a changeable shuttle for sewing machines, according to another embodiment of the present invention. description of the elements in the drawings> 1: shuttle 2: slide groove 3: rotary channel unit 4: main body 5, 15: coupling part, coupling protrusion 6, 16: stop part, stop step 10: outer shuttle 12: first body 13: second body 14: housing ring 17: positioning protrusion 18: positioning notch 19: rib protrusion 20: inner shuttle

Disclosure

Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a changeable shuttle for sewing machines which includes inner and outer shuttles for the supply of a lower thread, each of which is separated into several elements that can be easily assembled together, thus making separate replacement of each element possible, so that, when the replacement of the shuttle is required due to abrasion from using the shuttle over a long period, that is, due to abrasion due to friction occurring between a slide groove of an outer shuttle and a bearing rib of an inner shuttle during rotation of the shuttle, the whole shuttle is not replaced, but only the worn elements of the shuttle are replaced with new ones, thus increasing efficiency of the replacement of the shuttle and economical efficiency, and reducing the cost of replacement of the shuttle. Another object of the present invention is to provide a changeable shuttle for sewing machines which includes several elements that are easily disassembled or assembled together, unlike conventional shuttles integrated as single bodies, thus increasing accuracy and workability in manufacturing each element, enhancing the quality of products, and reducing manufacturing costs of the products, thereby reducing costs in purchase and maintenance such as replacement of elements.

Technical Solution In order to accomplish the above object(s), the present invention provides a changeable shuttle for sewing machines, in which a lower thread for sewing is provided, and comprising an outer shuttle and an inner shuttle. The inner shuttle is coupled at an upper end thereof to a rotary channel unit which is cut to be opened at a predetermined portion thereof and has a slide groove on an inner surface thereof. The inner shuttle includes first and second bodies and a housing ring to form a separable structure. The first body includes a stop step around a center of an outer surface thereof to form a stepped surface; a plurality of coupling protrusions on an upper end thereof; and a positioning protrusion at a predetermined position on the outer surface thereof.

Advantageous Effects In the present invention, a changeable shuttle for sewing machines includes inner and outer shuttles for supplying a lower thread, each of which is separated into several elements that can be easily assembled together, thus making separate replacement of each element possible. Therefore, when the replacement of the shuttle is required due to abrasion due to use of the shuttle over a long period, the whole shuttle is not replaced, but only worn elements of the shuttle are replaced with new ones, thus increasing efficiency of the replacement of the shuttle, and reducing the cost of replacing the shuttle, thereby increasing a life span of the shuttle. Furthermore, the changeable shuttle for supplying the lower thread includes several elements that are easily disassembled or assembled together, unlike conventional shuttles integrated as single bodies, thus increasing the accuracy and workability in manufacturing each element, enhancing the quality of products, and reducing manufacturing costs of the shuttle, thereby reducing purchase and maintenance cost, such as the replacement of elements.

Best Mode Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. As shown in FIGS. 2 through 7, a changeable shuttle 1 for sewing machines according to the present invention includes an outer shuttle 10 having a main body 4 to which a rotary channel unit 3 is rotatably coupled. The rotary channel unit 3 is cut to be opened at a predetermined portion thereof and has a slide groove 2 on an inner surface thereof. The changeable shuttle 1 further includes an inner shuttle 20 which is formed as a structure separated into first and second bodies 12 and 13 and a housing ring 14 having a ring shape. The main body 4 of the outer shuttle 10 has a coupling part 5 and a stop part 6 on an upper end thereof to form a stepped shape to be coupled to the rotary channel unit 3. The coupling part 5 and the stop part 6 respectively include a coupling groove 5' and a coupling hole 6' which communicate with each other. The rotary channel unit 3 has thereon an opening 3a which is formed through the slide groove 2 that is provided on the inner surface of the rotary channel unit 3. The rotary channel unit 3 further has a coupling groove 3b which is provided to a predetermined depth to communicate with the opening 3a. An oil feed pipe 10' is inserted into the coupling hole 6' which is provided on the stop part 6. A stop step 16 is provided around a center of an outer surface of the first body 12 of the inner shuttle 20 to form a stepped surface. A plurality of coupling protrusions 15 is provided on an upper end of the first body 12. A positioning protrusion 17 is provided at a predetermined position on the outer surface of the first body 12. The housing ring 14 of the inner shuttle 20 has on an inner surface thereof a positioning notch 18 to engage with the positioning protrusion 17 which is provided on the first body 12. A plurality of oil inflow notches 11 is provided at regular intervals on a rib protrusion 19 of an outer surface of the housing ring 14. A grooved part 14' is provided to a predetermined depth on a surface of the housing ring 14 which is in contact with the stop step 16 of the first body 12 while the housing ring 14 is fitted over the first body 12. FIG. 2 is an exploded perspective view of the changeable shuttle for sewing machines, according to the present invention. FIG. 3 is a perspective view of the changeable shuttle for sewing machines, according to the present invention. FIG. 4 is a sectional view of the changeable shuttle for sewing machines, according to the present invention. In the changeable shuttle 1 for sewing machines according to the present invention, the inner shuttle 20 is inserted into the outer shuttle 10. At this time, the housing ring 14 of the inner shuttle 20 engages with the slide groove 2 which is provided on the rotary- channel unit 3 of the outer shuttle 10. A rotating shaft (R) is inserted into and fastened by a locking bolt to a shaft hole 4' which is formed through the center of the main body 4 of the outer shuttle 10. The rotary channel unit 3 is fitted over the upper end of the main body 4 through the stop part 6 and the coupling part 5. Both an inner cover 7 and a covering 8 are coupled to the outer shuttle 10 by a locking bolt (S) to surround an outer surface of the outer shuttle 10. An outer cover 9 is coupled to the outer shuttle 10 to cover the inner cover 7. Furthermore, the main body 4 of the outer shuttle 10 has therein an oil storage unit 10a and an oil feed passage 10b to supply oil for lubrication to the slide groove 2 on which friction occurs while the inner shuttle 20 rotates in the outer shuttle 10. The oil feed passage 10b communicates with the coupling hole 6' formed on the stop part 6. Therefore, a predetermined amount of oil is supplied from the oil storage unit 10a to the coupling hole 6' through the oil feed passage 10b. Thereafter, the oil is supplied through the oil feed pipe 10' to the opening 3a formed on the rotary channel unit 3. FIG. 5 is a perspective view showing an enlargement of an important part of the changeable shuttle for sewing machines, according to the present invention. FIG. 5 illustrates that the rotary channel unit 3 is inserted into the main body 4 of the outer shuttle 10 of the changeable shuttle 1 by the stop part 6 and the coupling part 5 of the main body 4, and that the U-shaped slide groove 2 is formed on the inner surface of the rotary channel unit 3. The inner and outer covers 7 and 9 and the cover 8 are coupled to the outer surface of the main body 6 to guide the upper and lower threads for sewing. FIG. 6 is a perspective view showing an enlargement of another important part of the changeable shuttle for sewing machines, according to the present invention. FIG. 6 illustrates that the inner shuttle 20 of the changeable shuttle 1 is separated into the first body 12 and the second body 13, that the stud 12' integrally protrudes from the center of the first body 12, and that the housing ring 14 is fitted over the first body 12. The second body 13 is fitted over the first body 12 by the coupling protrusions 15 and the stop step 16 which are formed on the first body 12. The housing ring 14 is fitted over an outer surface of the first body 12 such that the positioning groove 18 of the housing ring 14 engages with the positioning protrusion 17 which is provided at a predetermined position on the outer surface of the first body 12. Thus, the housing ring 14 is prevented from undesirably rotating. FIG. 7 is an enlarged sectional view of a circled portion yh' of FIG. 4 to show the coupling of the inner shuttle 20 to the outer shuttle 10. The rotary channel unit 3 is coupled to the coupling part 5 and the stop part 6 which are provided on the main body 12 of the outer shuttle 10 to form the stepped shape. The rib protrusion 19 of the housing ring 14 moves in the slide groove 2 of the rotary channel unit 3 in a slide-type movement while being in contact with the slide groove 2. The housing ring 14 engages with the stop step 16 and the coupling protrusions 15 which are provided on the first body 12 of the inner shuttle 20. The oil, supplied to the coupling hole 6' through the 011 feed passage 10b of the main body 4 of the outer shuttle 10, is supplied to the opening 3a, which is formed on the rotary channel unit 3, through the oil feed pipe 10' which is inserted into the coupling hole 6' . At this time, due to the centrifugal force of the outer shuttle 10 rotating along with the rotating shaft (R) , a predetermined amount of oil is automatically supplied from the oil storage unit 10a through the oil feed passage 10b. FIG. 8 is an exploded perspective view of a changeable shuttle for sewing machines, according to another embodiment of the present invention. In this embodiment, a rotary channel unit 3, which has a slide groove 2 on an inner surface thereof and is coupled to a main body 4 of an outer shuttle 10, is divided into several parts. In the present invention, a drawing showing the construction of a sewing machine and a detailed description of its operation are omitted. Furthermore, because the mounting position of the changeable shuttle of the present invention, and the process of setting the changeable shuttle in the sewing machine are the same as those of typical sewing machines, further explanation is deemed unnecessary. The operation of the changeable shuttle for sewing machines according to the present invention will be described herein below. With reference to FIGS. 2 through 7, to supply the lower thread, the sewing machine requires the shuttle 1 to hold the bobbin (not shown) around which the lower thread is wound. The shuttle 1 includes the outer shuttle 10 and the inner shuttle 20. The rotating shaft, being operated by a drive unit (not shown) , is coupled to the outer shuttle 10. The bobbin, around which the lower thread is wound, is inserted into the inner shuttle 20. In the above-mentioned state in which the bobbin for supply of the lower thread is mounted to the shuttle 1, the sewing machine is operated for sewing. Then, for sewing, the lower thread is smoothly supplied from the bobbin mounted in the inner shuttle 20. During the sewing operation, the shuttle 1 is rotated by the rotating shaft coupled to the outer shuttle 10 at a predetermined speed. Due to the rotation, friction occurs at the junction between the outer shuttle 10 and the inner shuttle 20, at which the rib protrusion 19 provided on the housing ring 14 of the inner shuttle 10 engages with the slide groove 2 of the outer shuttle 10 in a contact state to maintain the coupling of the inner shuttle 20 to the outer shuttle 10. If the sewing machine is used over a long period, due to continuous friction, the junction part is worn. As such, due to friction due to the rotation of the shuttle 1, the slide groove 2 of the outer shuttle 10 and the rib protrusion 19 of the inner shuttle 20 are worn, so that a gap occurs at the junction between them. Due to the gap, vibration occurs during rotation of the inner shuttle 20. As a result, during the sewing operation, a desired straight or curved sewing line is not formed, but an irregular or undesirable zigzag sewing line is formed. Therefore, poor sewing quality results. Accordingly, when the shuttle 1 is worn, a replacement of the shuttle 1 supplying the lower thread is necessary to prevent the poor sewing quality. In conventional shuttles, because an outer shuttle and an inner shuttle are formed as a single body, even when only a slide groove or a rib protrusion is worn, a user must purchase a new shuttle and replace the worn shuttle with the new shuttle. However, in the changeable shuttle 1 of the present invention, the inner shuttle 20 and the outer shuttle 10 can each be separated into several elements which are easily assembled together (see, FIG. 2) . Thus, when the changeable shuttle 1 is worn, the whole changeable shuttle 1 is not replaced with a new one, but the worn elements, that is, the rotary channel 3 of the outer shuttle 10 and the housing ring 14 of the inner shuttle 20 can be separately replaced with a new one. As such, when the replacement of the rotary channel 3 or the housing ring 14 is required due to the abrasion of the shuttle 1, the shuttle 1 is first removed from the rotating shaft. The inner shuttle 20 is separated from the outer shuttle 10. Thereafter, the locking bolt is loosened using a separate tool. Then, the outer shuttle 10 is separated into the main body 4, the inner and outer covers 7 and 8, the covering 9 and the rotary channel unit 3, and the inner shuttle 20 is separated into the first and second bodies 12 and 13 and the housing ring 14. After the inner shuttle 20 and the outer shuttle 10 are separated into several elements, the worn rotary channel unit 3 or the housing ring 14 is replaced with a new one. Thereafter, they are reassembled together, thus completing the replacement of the shuttle 1 for supply of the lower thread. In the shuttle 1 of the present invention, the grooved part 14' is formed at the predetermined position on the housing ring 14 which is coupled to the first body 12 of the inner shuttle 20. Therefore, when the housing ring 14 is fitted over the first body 12, because a part of the stop step 16 of the first body 12 is covered with the grooved part 14', a gap is not defined at a part of the junction between the housing ring 14 and the first body 12, at which the grooved part 14' is formed. Thus, during the sewing operation, the lower thread is prevented from being undesirably held in the gap or being cut. As described above, the outer shuttle 10 and the inner shuttle 20 constituting the shuttle 1 each comprise several elements which can be easily assembled together. Particularly, the rotary channel unit 3 of the outer shuttle 10 and the housing ring 14 of the inner shuttle 20, which are worn due to friction due to the rotation, are not integrated into a single body, but they are formed as single bodies and separably assembled together. Therefore, when the shuttle 1 is worn, the whole shuttle 1 is not replaced with a new one, but only the worn rotary channel unit 3 and housing ring 14 can be replaced with new ones. In the meantime, in the changeable shuttle for sewing machines according to another embodiment of the present invention, as shown in FIG. 8, the rotary channel unit 3, which has the slide groove 2 on the inner surface thereof and is coupled to the main body 4 of the outer shuttle 10, is divided into several parts. This embodiment allows the user to selectively use the rotary channel unit 3 according to the size of the shuttle 1. In particular, this embodiment provides convenience in assembling and disassembling the shuttle 1 for the replacement of the rotary channel unit 3.