Structure for preventing empty rotation of bobbin when rotary hook stops

Abstract

The application discloses a kind of structures for preventing empty running of bobbin when rotary hook stops, including shuttle shell and the bobbin arranged in shuttle shell, the shuttle shell is provided with the shuttle shell spring piece that is attached to bobbin, brake groove is provided on the bobbin, brake part is provided on the shuttle shell spring piece, and the brake part can be engaged with brake groove.By optimizing the structure of the shuttle shell spring piece in the rotary hook, the brake groove provided on the bobbin is matched to complete the deceleration and stop of the bobbin in the idle state, the structure is exquisite, can improve production efficiency, and does not need to input external power to resist the inertia of the bobbin, the cost is low, and the practical application effect is good.The anti-idling structure is simple and effective, and can better promote the development of large-capacity rotary hook research and development in the industry, and increase the rotary hook capacity to most directly and effectively improve production efficiency.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a structure that prevents the bobbin from spinning freely when the shuttle stops. Background Technology

[0002] The rotary hook is one of the core components of a sewing machine. In existing sewing machines, after the rotary hook stops rotating from high speed, the bobbin, due to inertia, will spin freely to varying degrees. The larger the outer diameter and capacity of the bobbin, the greater the inertia, resulting in a larger angle of bobbin spin-free rotation. Under normal circumstances, the amount of bobbin rotation depends on the amount of thread required by the rotary hook. The bobbin should stop rotating simultaneously with the rotary hook. Conversely, if the bobbin does not stop, the thread inside will become loose and overlapped, leading to uneven bobbin thread tension, chaotic and overlapping thread feed, and broken bobbin thread. This reduces production efficiency and severely restricts the development of large-diameter and large-capacity rotary hooks; the larger the diameter, the greater the inertia and the more severe the spin-free rotation. Therefore, the industry urgently needs to solve these problems.

[0003] For example, a "sewing machine electromagnetic connecting rod anti-hair spin device" disclosed in Chinese patent literature, publication number "CN210856582U", includes a frame and a servo motor. A sewing machine body is installed on top of the frame, and a bobbin is installed on top of the sewing machine body. A connecting piece is installed on one side of the bobbin, and a magnet is installed inside the connecting piece. A rubber pad is installed inside the magnet. A push rod is installed on one side of the connecting piece, and a sliding sleeve is installed in the middle of the push rod. A connecting pin is installed on one side of the push rod, and a connecting rod is installed on one side of the connecting pin. A positioning pin is installed on one side of the connecting rod, and a limit frame is installed at the rear end of the positioning pin. A turntable is installed inside the limit frame, and ball bearings are installed on the outer wall of the turntable.

[0004] In the above scheme, the connecting rod drives the push rod to move through the connecting pin, which can pull the push rod to move back and forth and push the push rod to a suitable position so that the magnet can prevent the bobbin from spinning dry; however, the structure is complex, and an additional motor is required as a power source for preventing dry spinning, which is costly and requires regular maintenance and debugging, and does not help to improve production efficiency. Summary of the Invention

[0005] To address the problems of complex structure and high production cost of existing anti-hair spin devices, this invention provides a structure to prevent the hairpin from spinning when the rotary shuttle stops. By optimizing the structure of the shuttle shell spring in the rotary shuttle, and in conjunction with the brake groove set on the hairpin, the structure decelerates and stops the hairpin in the spinning state, improving the stability of the bottom line lead-out when the rotary shuttle switches between normal operation and stop. The structure is ingenious, requires no external power to counteract the inertia of the hairpin, is low in cost, and has good practical application results.

[0006] The second objective of this invention is to solve the problem that the frequent braking deformation of the bobbin due to heat affects the subsequent braking effect.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A structure to prevent the bobbin from spinning freely when a rotary hook stops includes a hook case and a bobbin disposed within the hook case. A hook case spring is disposed within the hook case and conforms to the bobbin. The bobbin has a brake groove, and the hook case spring has a brake part that engages with the brake groove. The hook case spring decelerates and brakes the bobbin by friction between the brake part and the brake groove on the bobbin. Through testing and optimization of the brake part, the following state is achieved: When the rotary hook is operating normally, the force of the bobbin driven by the thread is much greater than the force generated by the brake of the hook case spring. The frictional resistance of the brake part of the hook case spring against the brake groove is converted into heat and dissipated, thus not affecting the normal operation of the rotary hook. When the rotary hook stops, the brake part can decelerate and brake the spinning bobbin, ultimately ensuring that the bobbin stops synchronously with the rotary hook each time the thread is taken up, achieving stable operation of the equipment.

[0009] Preferably, the bobbin case spring includes an annular body, on which a positioning part and a braking part are provided. The braking part has a U-shaped structure. The braking part is a U-shaped concave structure, which can rub against the brake groove of the bobbin through its bottom surface. Since the bobbin case spring is an annular elastic element, the bobbin does not have the external force of the bottom thread during idle rotation. It will quickly decelerate and eventually stop rotating under the periodic friction between the brake groove and the braking part of the bobbin case spring, thereby realizing the prevention of idle rotation of the bobbin when the shuttle stops.

[0010] Preferably, the brake groove is a through-groove structure, comprising a core groove and arc-shaped grooves at both ends of the core groove, wherein the core groove is rectangular. The rectangular core groove utilizes its parallel sides to engage and align the U-shaped brake part, thereby achieving localized frictional deceleration of the bobbin case against the bobbin. The rectangular core groove can achieve "double-line contact" friction with the brake part; compared to other shapes, "double-line contact" can better utilize frictional resistance to achieve efficient braking of the bobbin. Meanwhile, the arc-shaped grooves at both ends of the core groove can avoid the outer edge of the brake part, preventing hard collisions between the outer edge of the brake part and the brake groove under bobbin vibration, which could cause deformation and affect the deceleration effect.

[0011] Preferably, the brake groove is a recessed structure, including a concave brake arc surface. The recessed brake groove, through its concave brake arc surface, enables frictional deceleration with the bobbin case spring. In particular, compared to a through-groove structure, the recessed brake groove improves the structural strength of the bobbin while avoiding openings in the bobbin.

[0012] Preferably, the positioning part includes at least two positioning holes, and the shuttle housing has corresponding through holes. The positioning holes of the shuttle housing spring piece are correspondingly arranged with the through holes on the shuttle housing, and can be connected through a fixing post on the outside of the shuttle to ensure that the shuttle housing spring piece and the shuttle housing are relatively fixed.

[0013] Preferably, the brake section has smooth transition sections on both sides of the annular body. The transition sections are where the brake section engages with the brake groove. The R-angle structure of the transition sections can eliminate hard collisions during deceleration and braking, ensuring that the rotating bobbin decelerates and stops through repeated friction rather than collisions. This avoids deformation of the bobbin case spring or bobbin due to collisions, which could affect the subsequent braking function and improve the working stability of the anti-spinning structure.

[0014] Preferably, the coefficient of thermal expansion of the brake part is less than that of the annular body. The brake part and the annular body are made of different materials; the coefficient of thermal expansion of the annular body is greater than that of the brake part, and the annular body is a closed loop. This means that when the entire shuttle shell spring expands due to friction and heat, the expansion degree of the annular body is greater than that of the brake part. The annular bodies on both sides of the brake part can compress the brake part, which is expanding in a directional direction, preventing a decrease in the U-shaped curvature of the brake part and thus reducing braking capacity. This ensures that the concave curvature of the brake part after heating remains essentially consistent with its original concave curvature, thereby achieving stable braking capacity and realizing the second objective of this application.

[0015] Preferably, the angle between adjacent brake grooves is different from the angle between adjacent brake parts. This difference in angle prevents the instantaneous engagement of all brake parts with the brake grooves. Such an engagement would cause resonance during high-speed rotation of the bobbin, causing the entire shuttle to vibrate synchronously with the frequent engagement and disengagement of the brake parts and brake grooves. Prolonged operation could lead to loosening and potential failure within the shuttle. With a different angle, the brake grooves and brake parts are in a state of "misaligned friction" deceleration, preventing resonance and extending the service life of the anti-spinning structure.

[0016] Preferably, a shuttle frame is provided below the shuttle case, a main shaft is provided in the middle of the shuttle frame, the bobbin is sleeved on the main shaft, and a bearing is provided between the main shaft and the bobbin. The bobbin is connected to the main shaft of the shuttle frame through the bearing, which can improve the stability of the bobbin's operation and avoid noise generation.

[0017] Therefore, the present invention has the following beneficial effects: (1) By optimizing the structure of the shuttle shell spring in the rotary shuttle, and cooperating with the brake groove set on the shuttle core, the shuttle core in the idle state is decelerated and stopped. The structure is exquisite, which can improve production efficiency. Moreover, there is no need to input external power to counteract the inertia of the shuttle core. The cost is low and the actual application effect is good. (2) The core groove of the rectangular structure can make "double-line contact" friction with the brake part. Compared with other shapes, "double-line contact" can better utilize friction resistance to complete the efficient stopping of the shuttle core. (3) When the entire shuttle shell spring is in the state of friction and heat expansion, the expansion degree of the annular body is greater than that of the brake part. The annular bodies on both sides of the brake part can squeeze the brake part which has a tendency to expand in the direction of extension, so as to avoid the reduction of the U-shaped arc of the brake part and the decrease of braking ability. The concave arc of the brake part after heating is basically consistent with the original concave arc, thereby obtaining stable braking ability. (4) The anti-idle structure is simple and effective, which can better promote the development of large-capacity rotary shuttles in the industry. Increasing the capacity of the rotary shuttle can most directly and effectively improve production efficiency. Attached Figure Description

[0018] Figure 1 This is an exploded view of the present invention.

[0019] Figure 2 This is an isometric view of the present invention.

[0020] Figure 3 for Figure 2 A magnified view of a portion of point A in the middle.

[0021] Figure 4 for Figure 1 A schematic diagram of the installation of the middle shuttle shell shrapnel.

[0022] Figure 5 This is a schematic diagram of the bobbin structure in Example 2.

[0023] In the diagram: 1. Shuttle shell, 11. Through hole, 2. Shuttle core, 3. Shuttle shell spring, 31. Annular body, 32. Positioning hole, 4. Brake groove, 41. Core groove, 42. Arc groove, 5. Brake part, 6. Transition part, 7. Shuttle frame, 71. Main shaft, 8. Bearing, 9. Concave brake arc surface. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0025] Example 1

[0026] like Figure 1As shown in Figure 2, a structure for preventing the bobbin from spinning freely when a shuttle stops includes a shuttle case 1 and a bobbin 2 disposed within the shuttle case 1. A shuttle case spring 3, fitted to the bobbin 2, is disposed within the shuttle case 1. A brake groove 4 is provided on the bobbin 2, and a brake part 5 is provided on the shuttle case spring 3. The brake part 5 can engage with the brake groove 4. The shuttle case spring 3 includes an annular body 31, on which a positioning part and a brake part 5 are provided. The brake part 5 has a U-shaped structure. The brake groove 4 includes a core groove 41 and arc-shaped grooves 42 at both ends of the core groove 41. The core groove 41 is rectangular. The positioning part includes at least two positioning holes 32, and a through hole 11 is provided on the shuttle case 1 corresponding to the positioning holes 32.

[0027] The bobbin case spring 3 decelerates and stops the bobbin 2 by friction between the brake part 5 and the brake groove 4 on the upper part of the bobbin 2. Through testing and optimization of the brake part 5, the following state is achieved: When the shuttle is working normally, the force of the bobbin 2 driven by the bottom thread is much greater than the force generated by the brake of the bobbin case spring 3. The frictional resistance of the brake part 5 of the bobbin case spring 3 against the brake groove 4 is converted into heat and dissipated, thus not affecting the normal operation of the shuttle. When the shuttle stops, the brake part 5 can decelerate and brake the idle bobbin 2, so that the bobbin 2 can stop synchronously with the shuttle every time the thread is taken back. This achieves stable operation of the equipment. The brake part 5 has a U-shaped concave structure, which can rub against the brake groove 4 of the bobbin 2 through its bottom surface. Since the bobbin case spring 3 is an annular elastic element, the bobbin 2 does not have the external force driven by the bottom thread during idle spinning. It will decelerate rapidly and eventually stop under the periodic friction between the brake groove 4 and the brake part 5 of the bobbin case spring 3, thus achieving the prevention of idle spinning of the bobbin 2 when the shuttle stops. The rectangular core groove 41 uses its parallel two sides to engage and align with the U-shaped brake part 5, thereby achieving local frictional deceleration of the bobbin 2 by the bobbin case spring 3. The rectangular core groove 41 can achieve "double-line contact" friction with the brake part 5. Compared with other shapes, "double-line contact" can better utilize frictional resistance to achieve efficient braking of the bobbin 2. The arc-shaped grooves 42 at both ends of the core groove 41 can avoid the outer edge of the brake part 5, preventing hard collision between the outer edge of the brake part 5 and the brake groove 4 when the bobbin 2 vibrates, which would cause deformation and affect the deceleration effect. The positioning hole 32 of the bobbin case spring 3 is set to correspond to the through hole 11 on the bobbin case 1. It can be connected through the fixing post on the outside of the shuttle to ensure that the bobbin case spring 3 and the bobbin case 1 are relatively fixed.

[0028] like Figure 3As shown in Figure 4, the brake part 5 is smoothly connected to the annular body 31 on both sides by transition parts 6. The coefficient of thermal expansion of the brake part 5 is less than that of the annular body 31. The transition part 6 is the position where the brake part 5 and the brake groove 4 are joined. The transition part 6 with its R-angle structure can eliminate the hard collision phenomenon during the deceleration and braking process, ensuring that the rotating bobbin 2 decelerates and stops through repeated friction rather than collision, avoiding the deformation of the bobbin case spring 3 or the bobbin 2 due to collision, which would affect the subsequent braking function and improve the working stability of the anti-free-spinning structure. The brake part 5 is made of a different material than the annular body 31. The coefficient of thermal expansion of the annular body 31 is greater than that of the brake part 5. Furthermore, the annular body 31 is a closed loop. This means that when the entire shuttle shell spring 3 expands due to friction and heat, the expansion degree of the annular body 31 is greater than that of the brake part 5. The annular bodies 31 on both sides of the brake part 5 can compress the brake part 5, which is expanding in a directional direction, preventing a decrease in the U-shaped curvature of the brake part 5 and thus reducing its braking capacity. This ensures that the concave curvature of the brake part 5 after heating remains essentially consistent with its original concave curvature, thereby achieving stable braking capacity and realizing the second inventive objective of this application. In this embodiment, the brake part 5 is made of 45# steel, and according to GB / T 4339-2008, its coefficient of thermal expansion at 20℃ is 11.59E-6 / K. The annular body 31 is made of aluminum alloy, and its coefficient of thermal expansion at 20℃ is 23.21E-6 / K. The transition part 6 is made of the same material as the brake part 5, and the brake part 5 and the annular body 31 are integrally formed by the transition part 6. The materials used for the annular body, the brake part, and the transition part include, but are not limited to, the materials described above. Any combination of materials in which the coefficient of thermal expansion of the annular body is greater than that of the coefficient of thermal expansion of the brake part and the transition part is applicable to this application.

[0029] It is worth noting that in this embodiment, the number of brake parts 5 on the shuttle shell spring 3 is two and evenly arranged, and the number of brake grooves 4 on the shuttle core 2 is three and also evenly arranged. Moreover, the included angle between adjacent brake grooves 4 is different from the included angle between adjacent brake parts 5. The different included angles can prevent the instantaneous situation where all brake parts 5 are fully engaged with the brake grooves 4. Such a situation would cause resonance during the high-speed rotation of the shuttle core 2, causing the entire shuttle to vibrate synchronously with the vibration of the frequent engagement and disengagement of the brake parts 5 and the brake grooves 4. Over a long period of operation, this could cause the internal parts of the shuttle to loosen and lead to potential failure. When the included angles are different, the brake grooves 4 and brake parts 5 are in a state of "misaligned friction" deceleration, which can prevent resonance and improve the service life of the anti-spinning structure.

[0030] In this embodiment, the rotary shuttle includes a shuttle case 1 and a shuttle frame 7. A shuttle case spring piece 3 is engaged within the inner wall of the shuttle case 1. A main shaft 71 is located in the middle of the shuttle frame 7, and the shuttle core 2 is sleeved on the main shaft 71. A bearing 8 is provided between the main shaft 71 and the shuttle core 2. The shuttle case spring piece 3 is changed from an open structure to a closed-loop structure, ensuring that the shuttle case spring piece 3 exerts equal force when the rotary shuttle core 2 rotates clockwise and counterclockwise. Figure 2 As shown, a brake part 5 is formed on the outermost arc of the bobbin case spring 3. The brake part 5 is connected to the annular body 31 of the bobbin case spring 3 on both sides of the transition part 6. Three U-shaped brake grooves 4 are machined on the bobbin core 2. The U-shaped brake grooves 4 are through grooves, and the transition part 6 is a rounded structure that corresponds to the U-shaped brake grooves 4 of the bobbin core 2. Through testing, the transition part 6 of the bobbin case spring 3 and the brake grooves 4 of the bobbin core 2 form a braking structure with appropriate friction (this friction is just enough to stop the force of the bobbin core 2 spinning freely). During normal operation, since the force of the bobbin core 2 driven by the bottom thread is much greater than the force generated by the spring brake, the friction is converted into internal energy dissipation through the elasticity of the bobbin case spring 3 itself, thus not affecting the normal operation of the rotary hook. When the rotary hook stops, the bobbin core 2 can also stop almost synchronously under the action of friction, ultimately achieving uniform and stable take-up each time, realizing stable finished product processing, avoiding the failure rate caused by the bobbin core 2 spinning freely, improving efficiency, reducing costs, and promoting the better development of large-capacity rotary hooks in the sewing industry. In particular, since the annular body 31 of the shuttle shell spring 3 has a different coefficient of thermal expansion than the brake part 5, the problem of brake failure caused by thermal expansion of the brake part 5 can be effectively avoided, thus improving the working stability.

[0031] Example 2

[0032] like Figure 5 As shown, in this embodiment, unlike Embodiment 1, the brake groove is a recessed structure, and the brake groove includes a concave brake arc surface. The recessed brake groove can achieve frictional deceleration with the bobbin case spring through the concave brake arc surface 9. In particular, compared with the through groove structure, the recessed brake groove has the characteristic of improving the structural strength of the bobbin while avoiding opening holes in the bobbin.

[0033] In addition to the above embodiments, within the scope disclosed in the claims and specification of this invention, the technical features of this invention can be reselected and combined to form new embodiments. These can be achieved by those skilled in the art without creative effort. Therefore, these embodiments not described in detail in this invention should also be regarded as specific embodiments of this invention and within the protection scope of this invention.

Claims

1. A structure for preventing the bobbin from spinning freely when the shuttle stops, comprising a shuttle case and a bobbin disposed within the shuttle case, characterized in that, The shuttle case is provided with a shuttle case spring piece that fits into the shuttle core. The shuttle core is provided with a brake groove. The shuttle case spring piece is provided with a brake part. The brake part can engage with the brake groove. The shuttle shell spring includes an annular body, on which a braking part is provided. The coefficient of thermal expansion of the braking part is less than that of the annular body. The annular body is a closed loop. The ring-shaped main body is provided with a positioning part, the braking part is a U-shaped structure, and there are two braking parts that are evenly arranged. The brake groove is a through groove structure, and the brake groove includes a core groove and arc-shaped grooves at both ends of the core groove. The core groove is rectangular, and the number of brake grooves is three and they are evenly arranged.

2. The structure for preventing the shuttle core from spinning freely when the shuttle stops according to claim 1, characterized in that, The brake groove is a recessed structure, and the brake groove includes a concave brake arc surface.

3. The structure for preventing the shuttle core from spinning freely when the shuttle stops according to claim 1, characterized in that, The positioning part includes at least two positioning holes, and the shuttle housing is provided with through holes corresponding to the positioning holes.

4. The structure for preventing the shuttle core from spinning freely when the shuttle stops according to claim 1, characterized in that, The brake section has smooth transition sections on both sides that connect to the annular body.

5. The structure for preventing the shuttle core from spinning freely when the shuttle stops according to claim 4, characterized in that, The transition section has an R-angle structure.

6. A structure for preventing the shuttle core from spinning freely when the shuttle stops according to any one of claims 1-5, characterized in that, The angle between adjacent brake grooves is different from the angle between adjacent brake sections.

7. A structure for preventing the shuttle core from spinning freely when the shuttle stops according to any one of claims 1-5, characterized in that, A shuttle frame is provided below the shuttle case, a main shaft is provided in the middle of the shuttle frame, the shuttle core is sleeved on the main shaft, and a bearing is provided between the main shaft and the shuttle core.

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