A leaf spring for a rotary hook and the rotary hook thereof

Abstract

This utility model discloses a leaf spring for a rotary hook and the same for the rotary hook. The leaf spring includes a base, multiple arc-shaped arms, and multiple positioning parts. All arc-shaped arms are formed by cutting the front part of the base, distributed around the central shaft hole of the base, extending circumferentially, with the free ends aligned clockwise and raised on the elastic contact surface. All protrusions are located on the radial center line of the arc-shaped arms, in the form of dots, short doodles, or arcs, and protrude on the elastic contact surface. When the above-mentioned leaf spring is used for a rotary hook, only the free ends of the arc-shaped arms and the protrusions contact the bobbin, facilitating heat dissipation, providing structural stability, and facilitating high-speed sewing operations.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine parts, specifically relating to a leaf spring for a rotary hook, and also to a rotary hook using the leaf spring. Background Technology

[0002] In a sewing machine shuttle, the shuttle body with the hook rotates at a constant speed, while the bobbin inside the shuttle body does not rotate. The bobbin inside the bobbin body rotates under the continuous pull of the bobbin thread. The hook can catch the upper thread, causing the upper thread to loop around the bobbin thread. To achieve stable rotation and effective braking of the bobbin, a leaf spring (CN117867769A) or a column spring (CN101613915A, CN221501421U) is installed between the bobbin body and the bobbin.

[0003] Leaf springs are commonly used in electrical contacts, anti-loosening bolt assemblies, automotive clutches, and refrigeration compressors. Existing rotary hook leaf springs employ a ring-shaped three-dimensional configuration to reduce friction. However, during high-speed sewing, these springs are prone to deformation, causing the bobbin to vibrate and leading to problems such as skipped stitches, tangling, thread breakage, needle breakage, and bobbin damage. Utility Model Content

[0004] The technical problem to be solved by this invention is how to improve the leaf spring of the sewing machine shuttle for use in high-speed sewing machines.

[0005] A first aspect of this utility model discloses a leaf spring for a rotary hook. The leaf spring includes:

[0006] A base portion, which is planar in shape, has a central shaft hole and a side surface configured as an elastic contact surface;

[0007] Multiple arc-shaped arms, formed by cutting the precursor of the base portion, are distributed around the central shaft hole, extending circumferentially, with their free ends aligned clockwise and raised on the elastic contact surface; and

[0008] Multiple positioning parts are located at the edge of the base part to cooperate with the side wall of the shuttle's shell to prevent the base part from rotating;

[0009] Each of the arcuate arms is provided with at least one protrusion that protrudes from the elastic contact surface;

[0010] All of the protrusions are in the shape of dots, dashes, or arcs, and are located on the radial center line of the arcuate arm.

[0011] In some embodiments of this application, each of the arcuate arms may have only one protrusion, which is dot-shaped.

[0012] In some embodiments of this application, each of the arc-shaped arms may have 2 to 6 protrusions, all of which are dot-shaped and distributed between the circumferential midpoint and the free end of the arc-shaped arm.

[0013] In some embodiments of this application, each of the arc-shaped arms may have only one protrusion, which is arc-shaped and has an arc length not less than half the arc length of the arc-shaped arm.

[0014] In some embodiments of this application, the leaf spring may be configured as an integral component made of a titanium-plated stainless steel spring steel sheet.

[0015] In some embodiments of this application, the positioning portion may optionally include four narrow strips divided into two radially opposite groups, or include a pair of radially protruding and opposite annular arcs.

[0016] In some embodiments of this application, the arc-shaped arms may be 2 to 6 in total, evenly distributed on one or two virtual rings, and these virtual rings coincide with the center of the central shaft hole.

[0017] A second aspect of this utility model discloses a rotary hook. This rotary hook is used in a sewing machine and includes: a leaf spring, as described in the first aspect, attached to the bottom surface of the inner cavity of the shuttle's bobbin case, with the elastic contact surface facing the shuttle's bobbin.

[0018] The following beneficial effects can be obtained by implementing the technical solution of this utility model.

[0019] This utility model discloses a leaf spring for a rotary hook and the same for the rotary hook. The leaf spring includes a base, multiple arc-shaped arms, and multiple positioning parts. All arc-shaped arms are formed by cutting the front part of the base, distributed around the central shaft hole of the base, extending circumferentially, with the free ends aligned clockwise and raised on the elastic contact surface. All protrusions are located on the radial center line of the arc-shaped arms, in the form of dots, short doodles, or arcs, and protrude on the elastic contact surface. When the above-mentioned leaf spring is used for a rotary hook, only the free ends of the arc-shaped arms and the protrusions contact the bobbin, facilitating heat dissipation, providing structural stability, and facilitating high-speed sewing operations. Attached Figure Description

[0020] The accompanying figures should be used in conjunction with the detailed implementation section.

[0021] Figure 1 This is a front view schematic diagram of the leaf spring in Embodiment 1;

[0022] Figure 2 This is a front view schematic diagram of the leaf spring in Embodiment 2;

[0023] Figure 3a This is a scaled front view of the leaf spring in Embodiment 3;

[0024] Figure 3b This is a sample photograph of the leaf spring in Example 3;

[0025] Figure 4a This is a scaled front view of the leaf spring in Example 4;

[0026] Figure 4b This is a scaled left view of the leaf spring in Example 4, in which the free ends of the two arc-shaped arms are raised by 0.25mm on the front (elastic contact surface);

[0027] Figure 5 This is a sample photograph of the leaf spring in Example 5;

[0028] Figure 6 This is a front view schematic diagram of the leaf spring in Embodiment Six.

[0029] Figure 3a , Figure 4a and Figure 4b In this text, the dimension unit is millimeters (mm).

[0030] Key annotations in the attached diagram:

[0031] 10, 10', 30, 30', 50, and 70 are leaf springs;

[0032] 10a, 30a, and 70a are the central shaft holes;

[0033] 11 and 71 are the first arc-shaped arms;

[0034] 12 and 72 are the second arc-shaped arms.

[0035] 31 is the third arc-shaped arm;

[0036] 32 is the fourth arc-shaped arm;

[0037] 11a, 12a, 31a, 32a, 71a, and 72a are clearance holes;

[0038] Numbers 101, 102, 103, 104, 301, 302, 303, 308, 501, and 701 are protruding parts;

[0039] 18, 38, and 78 are positioning parts. Detailed Implementation

[0040] The embodiments are described below with reference to the accompanying drawings.

[0041] In this specification, unless otherwise specified, "one embodiment," "some embodiments," and "other embodiments" are used to distinguish different embodiments and do not refer to all embodiments in general; the accompanying drawings are schematic diagrams, not scale diagrams; the directions / positions indicated by top, bottom, center, edge, inner, outer, far, near, long, wide, vertical, horizontal, up, down, front, back, left, right, etc., are based on the viewing angle of the accompanying drawings and should not be interpreted as the component / device being located in a specific position or facing a specific direction; the sequence words such as first, second, third, etc., are used to distinguish components / devices with the same function / name and have no sequential meaning.

[0042] Example 1

[0043] The leaf spring 10 has been disclosed.

[0044] The leaf spring 10 is an integral component made from a single, flat, titanium-plated stainless steel spring steel sheet with a thickness of 0.15 mm. That is, the precursor of the leaf spring 10 is a stainless steel spring steel sheet.

[0045] The leaf spring 10 is formed by cutting, stamping and other processes. It has a pair of arc-shaped arms, is low in weight, occupies little space and is simple to manufacture. It is used in the rotary hook of a sewing machine and is suitable for high-speed sewing. In the rotary hook, the leaf spring 10 is fixedly installed in the bobbin case and elastically abuts against the bobbin core through a pair of arc-shaped arms.

[0046] Please see Figure 1 The leaf spring 10 includes a base portion, a first arcuate arm 11, a second arcuate arm 12, a pair of fixing portions 18, and eight protrusions.

[0047] The front side of the base faces the bobbin, thus serving as an elastic contact surface.

[0048] The base is circular and has a central shaft hole 10a. Two fixing parts 18 are annular arcs, protruding from the circular outline of the base and symmetrically located... Figure 1 The two ends of the horizontal axis are dotted in the middle. With this structure, the leaf spring 10 can be sleeved on the central shaft of the shuttle case through the central shaft hole 10a, and a pair of fixing parts 18 can be inserted into the side wall slots of the shuttle case, so that it can be fixedly attached to the bottom surface of the inner cavity of the shuttle case without rotation.

[0049] The first arc-shaped arm 11 and the second arc-shaped arm 12 are both arc-shaped, with the same arc length and radial width (3.0 mm), and are formed by cutting the precursor (i.e., stainless steel spring steel sheet) of the base portion. Figure 1 The two arc-shaped arms are symmetrical about the center of the circle. That is, the first arc-shaped arm 11 and the second arc-shaped arm 13 are distributed on a virtual ring, which is concentric with the central shaft hole (the centers of the two arms coincide).

[0050] Correspondingly, the base portion has two arc-shaped through holes surrounding the central shaft hole 10a. The roots of both the first arc-shaped arm 11 and the second arc-shaped arm 12 are connected to one end of the arc-shaped through hole. The free ends of both the first arc-shaped arm 11 and the second arc-shaped arm 12 extend in a clockwise direction, that is, the clockwise direction of their free ends is consistent. The free ends of the first arc-shaped arm 11 and the second arc-shaped arm 12 are raised by 0.25mm on the front side (elastic contact surface).

[0051] The first arc-shaped arm 11 is fitted with the corresponding arc-shaped through hole with a clearance fit, and two clearance holes 11a are provided at the root. The second arc-shaped arm 12 is fitted with the corresponding arc-shaped through hole with a clearance fit, and two clearance holes 12a are provided at the root. This structure can avoid internal friction caused by elastic deformation, thereby reducing deformation resistance.

[0052] The eight protrusions are divided into two groups, each group located on an arc-shaped arm. The following description focuses only on the first arc-shaped arm 11.

[0053] The first arc-shaped arm 11 has four round, 1.0 mm diameter protrusions stamped on it. These four protrusions are located on the radial center line of the first arc-shaped arm 11 and protrude on the front side (i.e., the elastic contact surface). Among these four protrusions, protrusion 101 is located above the midpoint of the arc length of the first arc-shaped arm 11, protrusion 104 is adjacent to the circumferential edge of the free end of the first arc-shaped arm 11, and protrusions 102 and 103 are evenly distributed between protrusions 101 and 104.

[0054] Please note that, in order to avoid affecting the elastic deformation performance, the ends of the two arc-shaped arms should be spaced at a sufficient distance, and the edges of the two arc-shaped arms should also be spaced at a sufficient distance from the edge of the base. The above "sufficient distance" refers to at least 2.0 mm, for example, 2.0~4.0 mm; the circumferential distance between the eight protrusions and the root of the arc-shaped arms should be at least 4.0 mm, of which the protrusion 101 and the root of the arc-shaped arms are spaced at approximately 5 mm apart in the circumferential direction.

[0055] When the leaf spring 10 is used for rotary hooks, it abuts against the bobbin through the free ends and protrusions of the two arc-shaped arms. Its own structure is firm, the friction area is small and heat dissipation is easy, so that the bobbin rotates stably at high speed, thereby reducing problems such as skipped stitches, tangling, broken thread, broken needle and bobbin damage.

[0056] The rotary hook with leaf spring 10 features high sewing efficiency, long bobbin life, low maintenance frequency and operating costs, and is suitable for various industrial flatbed sewing machines, overlock sewing machines and other equipment. The specific technical advantages are as follows.

[0057] 1) Adopting an integrated molding process

[0058] The curved arm is designed based on dynamic matching of the bobbin axis, optimizing the force distribution during operation through geometric symmetry. The curved arm makes symmetrical multi-point contact with the bobbin center, balancing the rotational inertia of the shuttle and reducing vibrations caused by centrifugal force. Apart from the gap surrounding the curved arm, there are no other perforations or gaps, resulting in a robust structure that reduces stitch jitter caused by bobbin loosening.

[0059] 2) Prevents wire breakage

[0060] The leaf spring applies vertical pressure to the bobbin through preload, ensuring precise alignment of the bobbin thread exit. It compensates for bobbin thread tension fluctuations in real time, preventing thread breakage during reverse rotation (bobbin inertia after machine stop) and under no-load conditions, reducing thread retraction and frictional losses from idle spinning. Made of titanium-plated stainless steel, the leaf spring adaptively adjusts pressure during high-speed sewing, ensuring a continuous and stable output of bobbin thread, reducing breakage rates, and meeting the precision and efficiency requirements of the garment manufacturing and automotive interior industries.

[0061] 3) Optimization of conflicting structures

[0062] The eight dot-shaped protrusions on the leaf spring reduce the contact area and lower the coefficient of friction, effectively preventing heat accumulation during high-speed rotation. The grooves around the protrusions and on the back form cooling air channels, which, combined with a high-temperature resistant alloy, improve thermal conductivity, ensuring stable operation of the bobbin, preventing coating oxidation or deformation, extending service life, and reducing downtime for maintenance and consumable costs.

[0063] Example 2

[0064] The leaf spring 30 has been disclosed.

[0065] The leaf spring 30 is based on Example 1, with the following improvements.

[0066] Please see Figure 2 The leaf spring 30 includes a base portion, a third arc-shaped arm 31, a fourth arc-shaped arm 32, six protrusions, and two sets of four strip-shaped fixing portions 38.

[0067] The base portion is approximately arc-shaped and has a central shaft hole 30a. Four fixing parts 38, which protrude radially from the circular outline of the base portion, are located in two groups. Figure 2 The two ends of the horizontal axis of the dashed line.

[0068] The third arc-shaped arm 31 and the fourth arc-shaped arm 32 have the same arc length and are formed by cutting the precursor (i.e., the stainless steel spring steel sheet) of the base portion. Figure 2 The vertical axis relative to the dashed line is symmetrical on both sides but connected end to end. Correspondingly, the base has two arc-shaped through holes surrounding the central shaft hole 30a.

[0069] The roots of the third arc-shaped arm 31 and the fourth arc-shaped arm 32 are both connected to one end of the corresponding arc-shaped through hole. The free ends of the third arc-shaped arm 31 and the fourth arc-shaped arm 32 both extend in a clockwise direction, that is, the clockwise direction of their free ends is the same.

[0070] The third arc-shaped arm 31 is fitted with the corresponding arc-shaped through hole with clearance, and has two clearance holes 31a at its root. The fourth arc-shaped arm 32 is fitted with the corresponding arc-shaped through hole with clearance, and has two clearance holes 32a at its root.

[0071] The six protrusions are divided into two groups, each group located on an arc-shaped arm. The following description focuses only on the third arc-shaped arm 31.

[0072] The third arc-shaped arm 31 has three dot-shaped protrusions stamped on it. These three protrusions are located on the radial center line of the third arc-shaped arm 31 and protrude on the front side (i.e., the elastic contact surface). Of these three protrusions, protrusion 301 is located above the midpoint of the arc length of the third arc-shaped arm 31, protrusion 303 is adjacent to the circumferential edge of the free end of the third arc-shaped arm 31, and protrusion 302 is located between protrusion 301 and protrusion 303.

[0073] For other aspects of the leaf spring 30, please refer to Example 1.

[0074] Example 3

[0075] A leaf spring 10' has been disclosed.

[0076] The leaf spring 10' is based on Example 1, with the following improvements.

[0077] Please see Figure 3a and Figure 3b The leaf spring 10' has only two protrusions 101.

[0078] For other aspects of the leaf spring 10', please refer to Example 1.

[0079] Example 4

[0080] A 30' leaf spring has been disclosed.

[0081] The leaf spring 30' is based on Example 2, with the following improvements.

[0082] Please see Figure 4a The leaf spring 30' has only two protrusions 308. One protrusion 308 is located between the root of the third arc-shaped arm and the midpoint of the arc length. The other protrusion 308 is located between the root of the fourth arc-shaped arm and the midpoint of the arc length.

[0083] Figure 4b In the middle, the free ends of the two arc-shaped arms are raised by 0.25mm on the front (elastic contact surface).

[0084] For other aspects of the leaf spring 30', please refer to Embodiment 2 and Embodiment 1.

[0085] Example 5

[0086] The leaf spring 50 has been disclosed.

[0087] The leaf spring 50 is based on Example 2, with the following improvements.

[0088] Please see Figure 5 The leaf spring 50 has only two protrusions 501. One protrusion 501 is located at the midpoint of the arc length of the third arc arm. The other protrusion 501 is located at the midpoint of the arc length of the fourth arc arm.

[0089] For other aspects of the leaf spring 50, please refer to Embodiment 2 and Embodiment 1.

[0090] Example 6

[0091] The leaf spring 70 has been disclosed.

[0092] The leaf spring 70 is based on Example 1, with the following improvements.

[0093] Please see Figure 6 The leaf spring 60 includes a base portion, a first arcuate arm 71, a second arcuate arm 72, a pair of fixing portions 78, and two protrusions 701.

[0094] The base is provided with a central shaft hole 70a, the root of the first arc-shaped arm 11 is provided with two clearance holes 71a, and the root of the second arc-shaped arm 12 is provided with two clearance holes 72a.

[0095] The first arc arm 71 and the second arc arm 72 each have a protrusion 701 stamped on them.

[0096] The two protrusions 701 are both arc-shaped and are located on the two arc-shaped arms in a one-to-one correspondence.

[0097] Each protrusion 701 has one end located between the root of the arc arm and the midpoint of the arc length, and the other end adjacent to the circumferential edge of the free end of the arc arm.

[0098] For other aspects of the leaf spring 70, please refer to Example 1.

[0099] In another embodiment, each arcuate arm has only one protrusion, which consists of two welded concentric arcs. These two concentric arcs are distributed on both sides of the radial centerline of the arcuate arm, with a radial spacing of 1.0 mm—one-third of the radial width of the arcuate arm.

[0100] In other embodiments, each arcuate arm has 2, 5, or 6 protrusions. These protrusions are all short arcuate lines and are spaced at least 2.0 mm apart in the circumferential direction.

[0101] In other embodiments, the leaf spring includes 3, 4, 5, or 6 arc-shaped arms, each with a dot-shaped protrusion at the midpoint of its arc length. These arc-shaped arms, with the same arc length and radial width, are distributed circumferentially around a central shaft hole on a virtual ring, spaced circumferentially 4.0–6.0 mm apart, with their free ends aligned clockwise and raised on the elastic contact surface. Alternatively, these arc-shaped arms are distributed in two groups on two virtual rings, with the inner ring having a smaller arc length. The aforementioned virtual rings are concentric with the central shaft hole (the centers coincide).

[0102] The above embodiments, application examples, and technical analyses are intended to introduce the technical concept and features of this utility model, enabling those skilled in the art to implement the technical solution of this utility model, and do not constitute a limitation on the scope of protection claimed. Simple modifications and equivalent transformations to the embodiments are all within the above-mentioned scope of protection.

Claims

1. A leaf spring for a rotary hook, comprising: A base portion, which is planar in shape, has a central shaft hole and a side surface configured as an elastic contact surface; Multiple arc-shaped arms, formed by cutting the precursor of the base portion, are distributed around the central shaft hole, extend circumferentially, have the free ends aligned in the clockwise direction, and are raised on the elastic contact surface; as well as Multiple positioning parts are located at the edge of the base part to cooperate with the side wall of the shuttle's shell to prevent the base part from rotating; Its features are: Each of the arcuate arms is provided with at least one protrusion that protrudes from the elastic contact surface; All of the protrusions are located on the radial center line of the arcuate arm and are in the shape of dots, dashes, or arcs.

2. The leaf spring according to claim 1, characterized in that, Each of the arc-shaped arms has only one protrusion, which is dot-shaped.

3. The leaf spring according to claim 1, characterized in that, Each of the arc-shaped arms has 2 to 6 protrusions, all of which are dot-shaped and distributed between the circumferential midpoint and the free end of the arc-shaped arm.

4. The leaf spring according to claim 1, characterized in that, Each of the arc-shaped arms has only one protrusion, which is arc-shaped and has an arc length not less than half the arc length of the arc-shaped arm.

5. The leaf spring according to claim 1, characterized in that, Its configuration is a single component made of stainless steel spring steel sheets with titanium-plated surfaces.

6. The leaf spring according to claim 1, characterized in that, The positioning part includes four narrow strips divided into two radially opposite groups, or includes a pair of radially protruding and opposite annular arcs.

7. The leaf spring according to claim 1, characterized in that, There are 2 to 6 arc-shaped arms, distributed on one or two virtual rings, and these virtual rings coincide with the center of the central shaft hole.

8. A rotary hook for a sewing machine, characterized in that... include: The leaf spring according to any one of claims 1 to 7 is attached to the bottom surface of the inner cavity of the shuttle's housing, with the elastic contact surface facing the shuttle's core.

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