Thread catching prevention thread trimming knife and thread cutting mechanism for sewing machine

Abstract

The utility model provides a kind of thread hanging prevention thread cutting knife and thread cutting mechanism for sewing machine, and the thread hanging prevention thread cutting knife includes knife main part, knife tip part, thread distribution hooking groove and bobbin thread distribution groove;The outer surface of knife main part is equipped with first thread blocking edge at bobbin thread distribution groove, the inner surface of knife main part is equipped with second thread blocking edge at bobbin thread distribution groove, first thread blocking edge and second thread blocking edge face to face distribution, and form the thread passage channel that is communicated with bobbin thread distribution groove, first thread blocking edge and second thread blocking edge are side by side setting along the axial direction of rotating shuttle or along the movement direction of thread hanging prevention thread cutting knife, and second thread blocking edge is more away from rotating shuttle relative to the inner surface of knife main part.In normal sewing process, first thread blocking edge and second thread blocking edge can play the role of shielding bobbin thread, and the space that can hang thread is shrunk by forming narrow thread passage channel, so that the thread ring of normal sewing is blocked outside bobbin thread distribution groove, and the phenomenon of bobbin thread hanging in sewing process is eliminated.

Description

Technical Field

[0001] This utility model relates to the field of sewing machine technology, and in particular to an anti-snagging thread cutter for sewing machines, and an anti-snagging thread cutting mechanism including the anti-snagging thread cutter. Background Technology

[0002] Currently, most sewing machines are equipped with a thread-cutting mechanism, which is used to cut the starting thread on one side of the needle when sewing begins, and to cut the bottom thread and top thread at the end of the sewing process. This improves the automation level of the machine, enhances sewing efficiency, and ensures the quality of the garments.

[0003] In the prior art, the thread-cutting mechanism includes a fixed blade, a rotatable moving blade, a thread-cutting drive source, and a thread-cutting drive assembly. The thread-cutting drive source is connected to the moving blade through the thread-cutting drive assembly, driving the moving blade to extend and hook the thread, and the moving blade to rotate and engage with the fixed blade to cut the thread. For example, the double-moving-blade thread-cutting mechanism disclosed in Chinese invention patent CN118835402B. In the prior art, the moving blade is provided with a starting thread hooking groove, a first thread hooking groove (i.e., a separating thread hooking groove), a moving blade edge, and a second thread hooking groove (i.e., a top thread hooking groove). The separating thread hooking groove and the top thread hooking groove are distributed on the left and right edges of the moving blade. When starting to sew, the moving blade extends and moves the starting thread hooking groove to directly below the needle. When the first stitch is started, the needle moves down and then up in the starting thread hooking groove to hook the thread. After the set number of stitches is started, the thread is cut. At the end of sewing, firstly, the movable blade extends, and its tip at the cutting edge inserts into the thread loop to separate the thread. The left half of the thread loop and the bobbin thread enter the thread separating groove from the left opening. The right half of the thread loop slides from the tip of the movable blade along its right edge into the thread separating groove. Then, the movable blade rotates and engages with the fixed blade, cutting the thread and bobbin thread leading out from the thread separating groove. Clearly, the movable blade in the existing thread cutting mechanism simultaneously performs the functions of cutting thread during sewing, separating thread after sewing, and cutting thread after sewing, thereby improving the thread cutting effect.

[0004] However, the existing thread-cutting mechanism has the following drawbacks in practical applications: During the sewing process, the top thread and bottom thread intertwine to form a stitch; with each stitch, the rotary hook in the sewing machine first hooks the top thread, forming a loop, and then releases the thread. As the rotary hook expands the top thread loop, the thread's viscosity decreases, causing irregular disturbances in the loop. This is especially true when the top thread is mercerized or elastic, which are prone to loosening. The loop easily enters the thread-separating groove of the moving cutter and gets caught on the hook there, leading to failure to tighten the loop, pulling on the fabric and causing it to wrinkle and eventually break. Utility Model Content

[0005] In view of the shortcomings of the prior art described above, the technical problem to be solved by this utility model is to provide an anti-snagging thread cutter for sewing machines, which reduces the probability of the thread loop getting caught in the thread divider groove.

[0006] To achieve the above objectives, this utility model provides an anti-snagging thread cutter for a sewing machine, which is movably disposed on the outer periphery of the rotary hook in the sewing machine. The two surfaces of the anti-snagging thread cutter in the thickness direction are an inner surface facing the rotary hook and an outer surface facing away from the rotary hook, respectively.

[0007] The anti-snagging wire cutter includes a main body, a tip located at the end of the main body along the direction of movement of the anti-snagging wire cutter, and a wire-separating groove and a surface wire-separating groove that both penetrate the main body along the thickness direction of the main body. The wire-separating groove and the surface wire-separating groove are located at the two sides of the main body along the axial direction of the rotary hook.

[0008] The outer surface of the blade body has a first line-blocking edge at the line-separating groove, and the inner surface of the blade body has a second line-blocking edge at the line-separating groove. The first line-blocking edge and the second line-blocking edge are distributed face to face, and a narrow passage for passing through the line-separating groove is formed between them. The first line-blocking edge and the second line-blocking edge are arranged side by side along the axial direction of the rotary hook or along the movement direction of the anti-snagging thread-cutting knife. The second line-blocking edge is further away from the rotary hook relative to the inner surface of the blade body.

[0009] Furthermore, both the first and second blocking edges are inclined planes and are parallel to each other.

[0010] Furthermore, both the first and second blocking edges are chamfered surfaces.

[0011] Furthermore, the outer peripheral surface of the blade body has a surface sliding surface connecting the blade tip and the groove of the surface line dividing groove, and a surface bottom sliding surface connecting the blade tip and the groove of the dividing line hook groove. The surface sliding surface extends obliquely in a manner that the further away from the blade tip, the further away from the surface bottom sliding surface.

[0012] Furthermore, the main body of the knife is provided with a dividing hook at the opening of the dividing hook groove, and the inner surface of the dividing hook is provided with a dividing slope. The dividing slope extends obliquely in such a way that the further away from the opening of the dividing hook groove, the closer it is to the rotary hook. The dividing slope extends to the end of the dividing hook facing the opening of the dividing hook groove, and the dividing slope is a chamfered surface.

[0013] Furthermore, the outer surface of the blade body is provided with a surface line receiving portion on the side of the surface line dividing groove, and one end of the surface line receiving portion extends to the surface line dividing groove.

[0014] Furthermore, the outer surface of the blade body is provided with a stitch-starting part for cooperating with the stitch-pressing plate in the sewing machine to press the stitch, and the blade tip, the stitch-starting part and the first cutting edge are distributed in sequence;

[0015] The anti-snagging thread cutter also includes a blade mounting part fixed to the blade body. The outer surface of the blade mounting part is provided with a thread-pressing clearance groove. The starting thread pressing part and the thread-pressing clearance groove are arranged opposite each other along the axial direction of the rotary hook. The outer surface of the starting thread pressing part is closer to the thread pressing plate than the bottom surface of the groove facing the thread pressing plate of the thread-pressing clearance groove.

[0016] This utility model also provides an anti-snagging thread-cutting mechanism, including a movable main moving blade, a first thread-cutting drive source, a first thread-cutting transmission assembly, and a fixed auxiliary blade. The first thread-cutting drive source is connected to the main moving blade through the first thread-cutting transmission assembly. The main moving blade can engage with the auxiliary blade. The main moving blade and the auxiliary blade are distributed inward and outward along a direction away from the rotary hook in the sewing machine. The main moving blade is the anti-snagging thread-cutting blade as described above.

[0017] This utility model provides an anti-snagging thread-cutting mechanism, including a movable main moving blade, a first thread-cutting drive source, a first thread-cutting transmission assembly, and a movable auxiliary blade. The first thread-cutting drive source is connected to the main moving blade and the auxiliary blade through the first thread-cutting transmission assembly. The main moving blade can engage with the auxiliary blade. The main moving blade and the auxiliary blade are distributed inward and outward along a direction away from the rotary hook in the sewing machine. The main moving blade is the anti-snagging thread-cutting blade as described above.

[0018] This utility model further provides an anti-snagging thread-cutting mechanism, including a movable main moving blade, a first thread-cutting drive source, a first thread-cutting transmission assembly, a movable auxiliary blade, a second thread-cutting drive source, and a second thread-cutting transmission assembly. The first thread-cutting drive source is connected to the main moving blade via the first thread-cutting transmission assembly, and the second thread-cutting drive source is connected to the auxiliary blade via the second thread-cutting transmission assembly. The main moving blade can engage with the auxiliary blade. The main moving blade and the auxiliary blade are distributed inward and outward along a direction away from the rotary hook in the sewing machine. The main moving blade is the anti-snagging thread-cutting blade as described above.

[0019] As described above, the anti-snagging thread cutter and anti-snagging thread cutting mechanism for sewing machines involved in this utility model have the following beneficial effects:

[0020] The design of the first and second thread-blocking edges allows the right half of the top thread loop to smoothly slide into the top thread divider groove through the thread passage when the thread is cut at the end of sewing, driven by the anti-snagging thread cutter. However, during normal sewing, the first and second thread-blocking edges effectively conceal the top thread, especially loose threads. Furthermore, the narrow thread passage formed by the first and second edges reduces the space where threads can get caught, preventing the thread loop from entering the top thread divider groove. Ultimately, it becomes difficult for the top thread to enter the thread passage during sewing, thus eliminating the undesirable thread snagging phenomenon of the top thread slipping into the top thread divider groove during sewing. Attached Figure Description

[0021] Figure 1 and Figure 2 These are schematic diagrams of the structure of Embodiment 1 of the anti-snagging wire cutter of this application from different perspectives.

[0022] Figure 3 and Figure 4 These are schematic diagrams of the structure of Embodiment 2 of the anti-snagging wire cutter of this application from different perspectives.

[0023] Figure 5 and Figure 6 These are schematic diagrams of the structure of Embodiment 1 of the anti-snagging and wire-cutting mechanism of this application from different perspectives.

[0024] Figure 7 This is a schematic diagram of the structure of Embodiment 2 of the anti-snagging and wire-cutting mechanism of this application.

[0025] Figure 8 and Figure 9 These are schematic diagrams of the structure of Embodiment 3 of the anti-snagging and wire-cutting mechanism of this application from different perspectives.

[0026] Component labeling: Anti-snagging thread cutter 10, blade body 20, first cutting edge 21, blade tip 22, first bevel 221, second bevel 222, thread parting hook groove 23, first material reduction part 24, first sloped surface 241, second material reduction part 25, second sloped surface 251, third material reduction part 26, third sloped surface 261, thread parting hook 27, thread parting bevel 271, top thread parting groove 28, first thread blocking edge 291, second thread blocking edge 292, thread passage 210, top thread sliding surface 212, top and bottom thread sliding surface 213, top thread receiving part 215, seam starting and pressing part 216, seam starting hook groove 217, post-seam thread cutting receiving part 218, seam starting thread cutter Wire receiving part 219, barb part 220, blade mounting part 30, wire pressing clearance groove 31, wire pressing plate 40, auxiliary blade 50, first wire cutting drive source 61, second wire cutting drive source 62, first wire cutting drive crank 71, first wire cutting connecting rod 72, first wire cutting shaft 73, first wire cutting transmission crank 74, second wire cutting transmission crank 75, second wire cutting connecting rod 76, active blade holder 77, third wire cutting transmission crank 78, wire cutting transmission groove 79, auxiliary blade holder 710, wire cutting transmission pin 711, second wire cutting drive crank 712, third wire cutting connecting rod 713, second wire cutting shaft 714, fourth wire cutting transmission crank 715, fourth wire cutting connecting rod 716, suction pipe 80. Detailed Implementation

[0027] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0028] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0029] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0030] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0031] This utility model relates to the field of sewing machine technology, and in particular to an anti-snagging thread cutter 10 for a sewing machine, and an anti-snagging thread cutting mechanism including the anti-snagging thread cutter 10. For ease of description, in the following embodiments, the directions are defined as follows: the axial direction of the rotary hook in the sewing machine is defined as the left-right direction, the horizontal radial direction of the rotary hook in the sewing machine is defined as the front-back direction, and the vertical diameter direction of the rotary hook in the sewing machine is defined as the up-down direction; at the same time, the front direction is the direction of fabric movement when the sewing machine is in operation.

[0032] like Figure 5 ,or Figure 7 ,or Figure 8 As shown, the anti-snagging wire cutting mechanism involved in this application includes two interlocking blades. The anti-snagging wire cutting blade 10 involved in this utility model is a movable main blade in the anti-snagging wire cutting mechanism, and the other blade in the anti-snagging wire cutting mechanism is an auxiliary blade 50. The auxiliary blade 50 can be a fixed blade or a movable blade. The following provides a preferred embodiment of the anti-snagging wire cutting blade 10 and a preferred embodiment of the anti-snagging wire cutting mechanism.

[0033] Example 1 of the anti-snagging wire cutter 10

[0034] like Figure 5 ,or Figure 7 ,or Figure 8 As shown, the anti-snagging thread cutter 10 is movably disposed on the outer periphery of the rotary hook in the sewing machine. The movement of the anti-snagging thread cutter 10 can be either rotation around the lower axis of the sewing machine or translational movement. The following description takes the rotation of the anti-snagging thread cutter 10 around the lower axis as an example, that is, the anti-snagging thread cutter 10 is rotatably disposed on the outer periphery of the rotary hook in the sewing machine. The anti-snagging thread cutter 10 and the auxiliary blade 50 in the sewing machine are arranged sequentially in a direction away from the rotary hook. The two surfaces of the anti-snagging thread cutter 10 in the thickness direction are the inner surface and the outer surface, respectively. The inner surface of the anti-snagging thread cutter 10 faces the rotary hook and is away from the auxiliary blade 50, while the outer surface of the anti-snagging thread cutter 10 is away from the rotary hook and faces the auxiliary blade 50.

[0035] like Figure 1 and Figure 2As shown, the anti-snagging wire cutter 10 includes a main body 20, a first cutting edge 21 on the outer surface of the main body 20, a tip 22 at the front end of the main body 20 along the movement direction of the anti-snagging wire cutter 10, and a wire-separating groove 23 and a surface wire-separating groove 28 that both penetrate the main body 20 along its thickness direction. The first cutting edge 21 of the anti-snagging wire cutter 10 is used to cooperate with the second cutting edge of the auxiliary blade 50 to cut the wire. The wire-separating groove 23 and the surface wire-separating groove 28 are located at the left and right edges of the main body 20 along the axis of the rotary hook. The opening of the wire-separating groove 23 is located at the left edge of the main body 20 and extends to the left edge of the main body 20, while the opening of the surface wire-separating groove 28 is located at the right edge of the main body 20 and extends to the right edge of the main body 20. The outer peripheral surface of the blade body 20 has a bottom surface sliding surface 213 connected between the blade tip 22 and the groove of the dividing line groove 23, and a surface line sliding surface 212 connected between the blade tip 22 and the groove of the surface line dividing groove 28. The bottom surface sliding surface 213 is part of the left edge of the blade body 20, and the surface line sliding surface 212 is part of the right edge of the blade body 20.

[0036] When the sewing machine finishes sewing and thread cutting is required, as the needle moves upward during the last stitch, the anti-snagging thread cutter 10 rotates forward. The tip of the anti-snagging thread cutter 10 inserts into the top thread loop. The left half of the top thread loop and the bobbin slide relative to each other along the top and bottom thread sliding surfaces 213 until they slide into the thread separating groove 23. The right half of the top thread loop slides relative to each other along the top thread sliding surfaces 212 until it slides into the thread separating groove 28. Then, the anti-snagging thread cutter 10 rotates backward, pulling the bobbin and top thread in the thread separating groove 23 towards the auxiliary blade 50 until the first cutting edge 21 of the anti-snagging thread cutter 10 and the second cutting edge of the auxiliary blade 50 engage, cutting the bobbin and top thread leading out of the thread separating groove 23, thus achieving automatic thread cutting at the end of sewing.

[0037] Furthermore, such as Figure 1 and Figure 2As shown, the outer surface of the blade body 20 has a first thread-blocking edge 291 at the thread dividing groove 28, and the inner surface of the blade body 20 has a second thread-blocking edge 292 at the thread dividing groove 28. The first thread-blocking edge 291 and the second thread-blocking edge 292 are distributed facing each other, and a thread passage 210 communicating with the thread dividing groove 28 is formed between them. The first thread-blocking edge 291 is distributed to the right of the second thread-blocking edge 292, that is, the first thread-blocking edge 291 and the second thread-blocking edge 292 are arranged side by side along the axis of the rotary hook; and the second thread-blocking edge 292 is further away from the rotary hook relative to the inner surface of the blade body 20. With the arrangement of the first thread-blocking edge 291 and the second thread-blocking edge 292, when the thread is cut at the end of sewing, the right half of the top thread loop slides smoothly from the thread passage 210 into the thread dividing groove 28 under the action of the anti-snagging thread cutter 10. However, during normal sewing, the first thread stop 291 and the second thread stop 292 effectively conceal the top thread, especially preventing loose threads from slipping during sewing. The first thread stop 291 is further away from the auxiliary knife 50 relative to the outer surface of the knife body 20, so any top thread accidentally thrown around the first thread stop 291 during sewing is blocked by the outer surface of the knife body 20. Simultaneously, the second thread stop 292 is further away from the rotary hook relative to the inner surface of the knife body 20, so any top thread accidentally thrown around the second thread stop 292 during sewing is blocked by the inner surface of the knife body 20. Furthermore, the first thread stop 291 and the second thread stop 292 form a narrow thread passage 210, reducing the space available for thread entanglement and preventing the thread loop from being blocked outside the thread distribution groove 28 during normal sewing. Ultimately, the top thread is unlikely to enter the thread passage 210 during sewing, thus preventing the undesirable thread entanglement phenomenon of the top thread slipping into the thread distribution groove 28 during sewing.

[0038] Preferably, such as Figure 1 and Figure 2 As shown, both the first stop edge 291 and the second stop edge 292 are beveled surfaces and are parallel to each other. The first stop edge 291 is machined on the outer surface of the blade body 20 by chamfering, and the second stop edge 292 is machined on the inner surface of the blade body 20 by chamfering. That is, both the first stop edge 291 and the second stop edge 292 are chamfered surfaces, and together they form a chamfered structure with parallel structure provided at the surface line dividing groove 28.

[0039] Furthermore, such as Figure 1 and Figure 2As shown, the top thread sliding surface 212 is an inclined surface extending at an angle. The inclination is such that the top thread sliding surface 212 extends at an angle further away from the blade tip 22 and further away from the bottom thread sliding surface 213. That is, the top thread sliding surface 212 starts from the blade tip 22 and extends at an angle to the right and rear. In this way, the closer the top thread sliding surface 212 is to the top thread dividing groove 28, the narrower the empty area on its right side becomes, preventing the top thread loop from entering the top thread dividing groove 28 from the empty area on the right side of the top thread sliding surface 212 during normal sewing, and reliably avoiding the undesirable phenomenon of the top thread getting caught.

[0040] like Figure 1 As shown, the main body 20 of the blade is also provided with a thread-starting groove 217. The thread-starting groove 217 penetrates the main body 20 along its thickness direction and allows the sewing machine needle to pass through. In this embodiment, the tip 22, the first cutting edge 21, the thread-starting groove 23, and the thread-starting groove 217 of the anti-snagging thread cutter 10 are distributed sequentially from front to back; or, in other embodiments, the tip 22, the first cutting edge 21, the thread-starting groove 217, and the thread-starting groove 23 of the anti-snagging thread cutter 10 are distributed sequentially from front to back.

[0041] Before sewing begins, the anti-snagging thread cutter 10 and the auxiliary blade 50 are positioned behind the needle. When the sewing machine begins to sew, the first stitch is made, and the anti-snagging thread cutter 10 rotates forward, positioning the starting thread groove 217 directly below the needle; alternatively, when the sewing machine is started, or after the previous stitch is cut, the anti-snagging thread cutter 10 remains positioned with the starting thread groove 217 directly below the needle. Then, as the sewing machine begins its first stitch, the needle moves downwards, carrying the thread, and passes through the starting thread groove 217. The rotary hook then pulls the starting thread end on the needle side to below the anti-snagging thread cutter 10. The sewing machine continues to sew the first stitch. The needle moves upward, and after it passes through the starting stitch hook groove 217, the anti-snagging thread cutter 10 rotates backward, taking the starting thread with it. However, at this point, the first cutting edge 21 of the anti-snagging thread cutter 10 is some distance from the second cutting edge of the auxiliary blade 50, and the two do not engage. After the sewing machine has sewed the set number of stitches, the anti-snagging thread cutter 10 continues to rotate backward with the starting thread until the first cutting edge 21 of the anti-snagging thread cutter 10 and the second cutting edge of the auxiliary blade 50 engage, cutting the starting thread on one side of the needle, thus achieving the anti-snagging thread cutter at the start of the stitch. After the thread cutter is finished, both the anti-snagging thread cutter 10 and the auxiliary blade 50 are located behind the needle and will not interfere with the up-and-down movement of the needle during sewing.

[0042] Furthermore, such as Figure 1As shown, the blade body 20 has a subtractive portion on at least one of the front and rear sides of the wire-separating groove 23. This means that the subtractive portion can be provided only on the front side of the wire-separating groove 23, only on the rear side, or on both the front and rear sides. In this embodiment, the blade body 20 has subtractive portions on both the front and rear sides of the wire-separating groove 23. The two subtractive portions are a first subtractive portion 24 and a second subtractive portion 25. In this application, a subtractive portion refers to a part formed by removing material. After the material removal process, the outer surface of the first subtractive part 24 forms a first ramp surface 241, and the outer surface of the second subtractive part 25 forms a second ramp surface 251. Both the first ramp surface 241 and the second ramp surface 251 extend at an angle as they move further away from the dividing line hook groove 23 and closer to the auxiliary tool 50. That is, the first ramp surface 241, which is located on the front side of the dividing line hook groove 23, extends from the rear side of the dividing line hook groove 23 to the front and outward, and the second ramp surface 251, which is located on the rear side of the dividing line hook groove 23, extends from the front side of the dividing line hook groove 23 to the rear and outward. The inclination directions of the first ramp surface 241 and the second ramp surface 251 are exactly opposite.

[0043] During the initial thread cutting process and the final thread cutting process, there is a certain amount of interference fit between the outer surface of the anti-snagging thread cutter 10 and the auxiliary blade 50 to ensure that the first cutting edge 21 and the second cutting edge can reliably engage to cut the thread. Since the first cutting edge 21 and the thread-separating hook groove 23 are directly opposite each other in the front-back direction, and the anti-snagging thread cutter 10 has an empty groove structure without a solid part at the thread-separating hook groove 23, the amount of interference fit between the anti-snagging thread cutter 10 and the auxiliary blade 50 is zero at the thread-separating hook groove 23. This application forms a first climbing surface 241 and a second climbing surface 251 on the front and rear sides of the wire-splitting groove 23 by setting a first subtractive part 24 and a second subtractive part 25, respectively. With this configuration, during the wire-cutting process, when the anti-snagging wire-cutting blade 10 rotates forward, the first climbing surface 241 and the second climbing surface 251 successively contact the auxiliary blade 50. The first climbing surface 241 first gradually reduces the interference fit between the anti-snagging wire-cutting blade 10 and the auxiliary blade 50 to zero, and then the second climbing surface 251... The interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 is gradually increased from zero. Conversely, during the wire cutting process, when the anti-snagging wire cutter 10 rotates forward, the second climbing surface 251 and the first climbing surface 241 come into contact with the auxiliary blade 50 one after the other. The second climbing surface 251 first gradually reduces the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 to zero, and the first climbing surface 241 then gradually increases the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 from zero. That is, the first ramp surface 241 and the second ramp surface 251 can mitigate the change in the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 at the wire separating groove 23, preventing the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 from suddenly decreasing to zero at the wire separating groove 23 and suddenly increasing from zero. This allows the second cutting edge of the auxiliary blade 50 to smoothly pass through the wire separating groove 23, preventing the anti-snagging wire cutter 10 from colliding with the auxiliary blade 50 at the wire separating groove 23 and preventing jamming. This reduces the wear of the anti-snagging wire cutter 10 and gives it a longer service life.

[0044] Preferably, the first climbing surface 241 is machined on the outer surface of the first subtractive part 24 by chamfering, and the second climbing surface 251 is machined on the outer surface of the second subtractive part 25 by chamfering, so that both the first climbing surface 241 and the second climbing surface 251 are chamfered surfaces.

[0045] Furthermore, such as Figure 1As shown, along the movement direction of the anti-snagging wire cutter 10, a third subtractive part 26 is provided at the rear end of the main body 20 away from the tip 22. The outer surface of the third subtractive part 26 is a third climbing surface 261. The third climbing surface 261 extends obliquely towards the tip 22 and towards the auxiliary blade 50, that is, the third climbing surface 261 extends obliquely forward and outward. The oblique manner of the third climbing surface 261 is consistent with the oblique manner of the first climbing surface 241. Thus, when the anti-snagging wire cutter 10 rotates forward to extend its blade, the third ramp surface 261 gradually reduces the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 at its rear edge to zero; when the anti-snagging wire cutter 10 rotates backward to retract its blade, the third ramp surface 261 gradually increases the interference fit between the anti-snagging wire cutter 10 and the auxiliary blade 50 at its rear edge, allowing the auxiliary blade 50 to pass smoothly through the rear edge of the anti-snagging wire cutter 10 and be smoothly lifted, avoiding collision between the anti-snagging wire cutter 10 and the auxiliary blade 50 at the rear edge of the anti-snagging wire cutter 10, thereby increasing the stability and service life of the tool during movement. Preferably, the third ramp surface 261 is machined on the outer surface of the third subtractive part 26 by chamfering, thus the third ramp surface 261 is a chamfered surface.

[0046] Furthermore, such as Figure 1 and Figure 2 As shown, the outer surface of the blade tip 22 is provided with a first bevel 221. The first bevel 221 extends obliquely away from the thread separating groove 23 and the auxiliary blade 50, that is, the first bevel 221 extends obliquely outward from the front end of the blade tip 22. The inner surface of the blade tip 22 is provided with a second bevel 222. The second bevel 222 extends obliquely away from the thread separating groove 23 and the rotary hook, that is, the second bevel 222 extends obliquely inward from the front end of the blade tip 22. In this way, the front end of the blade tip 22 forms a sharp point, which allows the blade tip 22 to better separate and enlarge the thread loop when cutting the thread at the end of sewing. Preferably, both the first bevel 221 and the second bevel 222 are machined on the outer and inner surfaces of the blade tip 22 by chamfering, so both the first bevel 221 and the second bevel 222 are chamfered surfaces.

[0047] Furthermore, such as Figure 1As shown, the outer surface of the blade body 20 is provided with a post-sewing thread-cutting receiving portion 218 and a starting-sewing thread-cutting receiving portion 219. The post-sewing thread-cutting receiving portion 218 is connected between the first cutting edge 21 and the parting hook groove 23, and the starting-sewing thread-cutting receiving portion 219 is connected between the first cutting edge 21 and the starting-sewing hook groove 217. In this embodiment, since the parting hook groove 23 is located in front of the starting-sewing hook groove 217, the post-sewing thread-cutting receiving portion 218 is a part of the starting-sewing thread-cutting receiving portion 219. In other embodiments, when the starting-sewing hook groove 217 is located in front of the parting hook groove 23, the starting-sewing thread-cutting receiving portion 219 is a part of the post-sewing thread-cutting receiving portion 218. During starting-sewing thread cutting, the starting thread end drawn from the starting hook groove 217 is received in the starting-sewing thread-cutting receiving portion 219 and cut at the first cutting edge 21. When the sewing is finished and the thread is cut, the left half of the top thread and the bottom thread drawn out from the thread guide groove 23 are placed in the thread cutting receiving part 218 after sewing and are cut at the first cutting edge 21.

[0048] Preferably, such as Figure 1 As shown, the outer surface of the blade body 20 has a thread receiving portion 215 on the side of the thread dividing groove 28, and the rear end of the thread receiving portion 215 extends to the thread dividing groove 28. When cutting the thread at the end of sewing, the right half of the thread that does not need to be cut, which is drawn out from the thread dividing groove 28, is received in the thread receiving portion 215. At the same time, the blade body 20 has barbs 220 distributed on the front side of the thread dividing groove 28 at the opening of the thread dividing groove 28. The thread receiving portion 215 covers the outer surface of the barbs 220, and the barbs 220 can prevent the right half of the thread from coming off during the waiting process, so that the length of the thread left on the needle after cutting is stable. In this embodiment, the thread receiving portion 215, the thread receiving portion after sewing 218, and the thread receiving portion at the beginning of sewing 219 are all concave structures (i.e., recessed structures) provided on the outer surface of the blade body 20.

[0049] Furthermore, such as Figure 1 and Figure 2As shown, the main body 20 of the blade has a dividing hook 27 at the opening of the dividing hook groove 23, and a second subtractive part 25 is provided at the rear end of the dividing hook 27 facing the opening of the dividing hook groove 23. The inner surface of the dividing hook 27 has a dividing slope 271, which extends at an angle that gets closer to the rotary hook the further away from the opening of the dividing hook groove 23. That is, the dividing slope 271 extends forward and inward from the rear end of the dividing hook 27. The second ramp surface 251 on the outer surface of the dividing hook 27 and the dividing slope 271 on the inner surface of the dividing hook 27 both extend rearward to the rear end of the dividing hook 27 facing the opening of the dividing hook groove 23. The setting of the dividing slope 271 allows the left half of the top thread and the bottom thread to slide more smoothly into the opening of the dividing hook groove 23 at the rear end of the dividing hook 27, avoiding the left half of the top thread and the bottom thread being hooked off during the process. Preferably, the dividing line slope 271 is machined on the inner surface of the dividing line hook 27 by chamfering, so the dividing line slope 271 is a chamfered surface.

[0050] Furthermore, such as Figure 1 As shown, the outer surface of the blade body 20 is provided with a starting stitch pressing part 216 for cooperating with the pressing plate 40 in the sewing machine to press the thread. The blade tip 22, the starting stitch pressing part 216 and the first cutting edge 21 are distributed in sequence, with the starting stitch pressing part 216 adjacent to the first cutting edge 21. The pressing plate 40 in the sewing machine is located on the rear side of the needle and is fixedly set. The pressing plate 40 is also arranged on the outer periphery of the auxiliary blade 50, and the front end of the pressing plate 40 cooperates with the starting stitch pressing part 216 of the anti-snagging thread cutter 10 to press the thread. When the sewing machine starts sewing and cuts the thread, during the process of starting the second stitch, the third stitch, and up to the set number of stitches, the first cutting edge 21 of the anti-snagging thread cutter 10 and the second cutting edge of the auxiliary blade 50 do not engage. However, the starting thread end is clamped between the front end of the pressing plate 40 and the starting pressing part 216 of the anti-snagging thread cutter 10, preventing the starting thread end from coming off and reliably achieving the prevention of bird nests during sewing and thread cutting.

[0051] Preferably, such as Figure 1 and Figure 2As shown, the anti-snagging thread cutter 10 also includes a blade mounting part 30, which is located on the right side of the blade body 20 and the two are fixed together. In this embodiment, the blade body 20 and the blade mounting part 30 are integrally formed; of course, in other embodiments, the blade body 20 and the blade mounting part 30 are two independent parts and are fixed by screws. The outer surface of the blade mounting part 30 is provided with a thread-pressing relief groove 31. The starting thread-pressing part 216 and the thread-pressing relief groove 31 are arranged opposite each other along the axial direction of the rotary hook, that is, the thread-pressing relief groove 31 is located on the right side of the starting thread-pressing part 216; the outer surface of the starting thread-pressing part 216 is closer to the thread-pressing piece 40 than the bottom surface of the groove facing the thread-pressing piece 40 of the thread-pressing relief groove 31. Thus, when the starting stitch pressing part 216 of the pressing plate 40 and the anti-snagging thread cutter 10 cooperate to press down the starting stitch, the setting of the pressing groove 31 ensures that the anti-snagging thread cutter 10 will not lift the pressing plate 40 at this point, thereby ensuring the pressing effect of the pressing plate 40.

[0052] Example 2 of the anti-snagging wire cutter 10

[0053] The difference between Embodiment 2 of the anti-snagging wire cutter 10 and Embodiment 1 is only that the first and second wire-blocking edges 291 and 292 are positioned differently at the wire-separating groove 28. In Embodiment 2 of the anti-snagging wire cutter 10, as... Figure 3 and Figure 4 As shown, the first line-blocking edge 291 is distributed on the rear side of the second line-blocking edge 292, and the first line-blocking edge 291 and the second line-blocking edge 292 are arranged side by side along the movement direction of the anti-snagging wire cutter 10.

[0054] In summary, the aforementioned anti-snagging thread cutter 10 has the advantages of preventing bird nests by cutting threads at the start of sewing, automatically cutting threads at the end of sewing, preventing threads from snagging during normal sewing, good stability during movement, and a long service life of the blade, effectively improving sewing performance.

[0055] Example 1 of the anti-snagging and wire-cutting mechanism

[0056] One embodiment of the anti-snagging and wire-cutting mechanism is a single-moving blade, single-wire-cutting drive source structure, that is, the auxiliary blade 50 is a fixed blade. Specifically: as follows: Figure 5 and Figure 6 As shown, one embodiment of the anti-snagging thread-cutting mechanism includes a movable main movable blade, a first thread-cutting drive source 61, a first thread-cutting transmission assembly, and a fixed auxiliary blade 50 with a second cutting edge. The main movable blade and the auxiliary blade 50 are distributed inward and outward in a direction away from the rotary hook in the sewing machine. The first thread-cutting drive source 61 is connected to the main movable blade via the first thread-cutting transmission assembly, driving the main movable blade to rotate around the lower shaft of the sewing machine, so that the first cutting edge 21 can engage with the second cutting edge. In particular, the main movable blade is any embodiment of the anti-snagging thread-cutting blade 10 described above.

[0057] In Embodiment 1 of the anti-snagging and wire-cutting mechanism, as follows: Figure 5 and Figure 6 As shown, the first thread-cutting drive source 61 is a motor and is fixed to the bottom of the sewing machine base plate. The first thread-cutting transmission assembly includes a first thread-cutting drive crank 71 fixed to the motor shaft of the first thread-cutting drive source 61, a first thread-cutting connecting rod 72, a first thread-cutting shaft 73 rotatably supported in the sewing machine base plate, a first thread-cutting transmission crank 74 fixed to the right end of the first thread-cutting shaft 73, a second thread-cutting transmission crank 75 fixed to the left end of the first thread-cutting shaft 73, a second thread-cutting connecting rod 76, and an active blade holder 77 rotatably mounted in the sewing machine base plate. The two ends of the first thread-cutting connecting rod 72 are hinged to the first thread-cutting drive crank 71 and the first thread-cutting transmission crank 74, respectively. The two ends of the second thread-cutting connecting rod 76 are hinged to the second thread-cutting transmission crank 75 and the active blade holder 77, respectively. The anti-snagging thread cutter 10 is fixed to the active blade holder 77 by screws.

[0058] Example 2 of the anti-snagging and wire-cutting mechanism

[0059] Embodiment two of the anti-snagging and wire-cutting mechanism is a dual-moving-blade, single-wire-cutting-drive-source structure, where the auxiliary blade 50 is a movable moving blade. Specifically: as follows... Figure 7 As shown, the second embodiment of the anti-snagging thread-cutting mechanism includes a movable main moving blade, a first thread-cutting drive source 61, a first thread-cutting transmission assembly, and a movable auxiliary blade 50 with a second cutting edge. The main moving blade and the auxiliary blade 50 are distributed inward and outward along a direction away from the rotary hook in the sewing machine. The first thread-cutting drive source 61 is connected to the main moving blade and the auxiliary blade 50 through the first thread-cutting transmission assembly, driving the main moving blade and the auxiliary blade 50 to rotate around the lower shaft of the sewing machine, so that the first cutting edge 21 can engage with the second cutting edge. In particular, the main moving blade is any embodiment of the above-described anti-snagging thread-cutting blade 10.

[0060] In Embodiment 2 of the anti-snagging and wire-cutting mechanism, such as Figure 7As shown, the first thread-cutting drive source 61 is a motor and is fixed to the bottom of the sewing machine base plate. The first thread-cutting transmission assembly includes a first thread-cutting drive crank 71 fixed to the motor shaft of the first thread-cutting drive source 61, a first thread-cutting connecting rod 72, a first thread-cutting shaft 73 rotatably supported in the sewing machine base plate, a first thread-cutting transmission crank 74 fixed to the right end of the first thread-cutting shaft 73, a second thread-cutting transmission crank 75 and a third thread-cutting transmission crank 78 both fixed to the left end of the first thread-cutting shaft 73, a second thread-cutting connecting rod 76, an active blade holder 77 rotatably mounted in the sewing machine base plate, an auxiliary blade holder 710 rotatably mounted in the sewing machine base plate, and a component fixed to the auxiliary blade holder. The wire-cutting drive pin 711 on 710, the two ends of the first wire-cutting connecting rod 72 are respectively hinged to the first wire-cutting drive crank 71 and the first wire-cutting transmission crank 74, the second wire-cutting transmission crank 75, the third wire-cutting transmission crank 78 and one end of the second wire-cutting connecting rod 76 are coaxially hinged, the other end of the second wire-cutting connecting rod 76 is hinged to the active blade holder 77, the anti-snagging wire-cutting knife 10 is fixed to the active blade holder 77 by screws, the third wire-cutting transmission crank 78 has a wire-cutting transmission groove 79 that slides with the wire-cutting drive pin 711, and the auxiliary knife 50 is fixed to the auxiliary blade holder 710 by screws.

[0061] Example 3 of the anti-snagging and wire-cutting mechanism

[0062] Embodiment three of the anti-snagging and wire-cutting mechanism is a dual-moving-blade, dual-wire-cutting-drive-source structure, where the auxiliary blade 50 is a movable moving blade. Specifically: as follows... Figure 8 and Figure 9 As shown, Embodiment 3 of the anti-snagging thread-cutting mechanism includes a movable main movable blade, a first thread-cutting drive source 61, a first thread-cutting transmission assembly, a movable auxiliary blade 50 with a second cutting edge, a second thread-cutting drive source 62, and a second thread-cutting transmission assembly. The main movable blade and the auxiliary blade 50 are distributed inward and outward in a direction away from the rotary hook in the sewing machine. The first thread-cutting drive source 61 is connected to the main movable blade via the first thread-cutting transmission assembly, driving the main movable blade to rotate around the lower shaft of the sewing machine. The second thread-cutting drive source 62 is connected to the auxiliary blade 50 via the second thread-cutting transmission assembly, driving the auxiliary blade 50 to rotate around the lower shaft of the sewing machine; thereby enabling the first cutting edge 21 to engage with the second cutting edge. In particular, the main movable blade is any embodiment of the above-described anti-snagging thread-cutting blade 10.

[0063] In Embodiment 3 of the anti-snagging and wire-cutting mechanism, such as Figure 8 and Figure 9As shown, both the first thread-cutting drive source 61 and the second thread-cutting drive source 62 are motors and are fixed to the bottom of the sewing machine base plate. The first thread-cutting transmission assembly includes a first thread-cutting drive crank 71 fixed on the motor shaft of the first thread-cutting drive source 61, a first thread-cutting connecting rod 72, a first thread-cutting shaft 73 rotatably supported in the sewing machine base plate, a first thread-cutting transmission crank 74 fixed to the right end of the first thread-cutting shaft 73, a second thread-cutting transmission crank 75 fixed to the left end of the first thread-cutting shaft 73, a second thread-cutting connecting rod 76, and an active blade holder 77 rotatably mounted in the sewing machine base plate. The two ends of the first thread-cutting connecting rod 72 are hinged to the first thread-cutting drive crank 71 and the first thread-cutting transmission crank 74, respectively. The two ends of the second thread-cutting connecting rod 76 are hinged to the second thread-cutting transmission crank 75 and the active blade holder 77, respectively. The anti-snagging thread cutter 10 is fixed to the active blade holder 77 by screws. The second thread-cutting drive assembly includes a second thread-cutting drive crank 712 fixed on the motor shaft of the second thread-cutting drive source 62, a third thread-cutting connecting rod 713, a second thread-cutting shaft 714 rotatably supported in the sewing machine base plate, a third thread-cutting drive crank 78 fixed to the right end of the second thread-cutting shaft 714, a fourth thread-cutting drive crank 715 fixed to the left end of the second thread-cutting shaft 714, a fourth thread-cutting connecting rod 716, and an auxiliary blade holder 710 rotatably mounted in the sewing machine base plate. The two ends of the third thread-cutting connecting rod 713 are hinged to the second thread-cutting drive crank 712 and the third thread-cutting drive crank 78, respectively. The two ends of the fourth thread-cutting connecting rod 716 are hinged to the fourth thread-cutting drive crank 715 and the auxiliary blade holder 710, respectively. The auxiliary blade 50 is fixed to the auxiliary blade holder 710 by screws.

[0064] Furthermore, such as Figure 5 and Figure 6 As shown, or as Figure 7 As shown, or as Figure 8 and Figure 9 As shown, the three embodiments of the above-mentioned anti-snagging thread cutting mechanism also include a suction pipe 80. The suction pipe 80 is disposed on the outer periphery of the anti-snagging thread cutting knife 10 and aligned with the outer surface of the anti-snagging thread cutting knife 10. After the thread is cut, the cut thread end is sucked away by the suction pipe 80.

[0065] In summary, this utility model effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0066] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A thread-snagging cutter for a sewing machine, movably disposed on the outer periphery of a rotary hook in a sewing machine, wherein the thread-snagging cutter (10) has two surfaces in the thickness direction, namely an inner surface facing the rotary hook and an outer surface facing away from the rotary hook; The anti-snagging wire cutter (10) includes a main body (20), a tip (22) located at the end of the main body (20) along the movement direction of the anti-snagging wire cutter (10), and a wire-splitting groove (23) and a surface wire-splitting groove (28) that both penetrate the main body (20) along the thickness direction of the main body (20). The wire-splitting groove (23) and the surface wire-splitting groove (28) are located at the two sides of the main body (20) along the axial direction of the rotary hook. Its features are: The outer surface of the blade body (20) is provided with a first line-blocking edge (291) at the face line dividing groove (28), and the inner surface of the blade body (20) is provided with a second line-blocking edge (292) at the face line dividing groove (28). The first line-blocking edge (291) and the second line-blocking edge (292) are distributed face to face, and a thread passage (210) communicating with the face line dividing groove (28) is formed between them. The first line-blocking edge (291) and the second line-blocking edge (292) are arranged side by side along the axis of the rotary hook or along the movement direction of the anti-snagging thread cutter (10). The second line-blocking edge (292) is further away from the rotary hook than the inner surface of the blade body (20).

2. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The first blocking edge (291) and the second blocking edge (292) are both inclined planes and are parallel to each other.

3. The anti-snagging thread cutter for a sewing machine according to claim 1 or 2, characterized in that: Both the first blocking edge (291) and the second blocking edge (292) are chamfered surfaces.

4. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The outer peripheral surface of the blade body (20) has a surface sliding surface (212) connecting the blade tip (22) and the groove of the surface line dividing groove (28), and a surface bottom sliding surface (213) connecting the blade tip (22) and the groove of the dividing line hook groove (23). The surface sliding surface (212) extends obliquely as it moves further away from the blade tip (22) and the surface bottom sliding surface (213).

5. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The main body of the knife (20) is provided with a dividing hook (27) at the opening of the dividing hook groove (23). The inner surface of the dividing hook (27) is provided with a dividing slope (271). The dividing slope (271) extends obliquely in such a way that the further away from the opening of the dividing hook groove (23) the closer to the rotary hook. The dividing slope (271) extends to the end of the dividing hook (27) facing the opening of the dividing hook groove (23). The dividing slope (271) is a chamfered surface.

6. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The outer surface of the blade body (20) is provided with a face line receiving portion (215) on the side of the face line dividing groove (28), and one end of the face line receiving portion (215) extends to the face line dividing groove (28).

7. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The outer surface of the blade body (20) is provided with a stitching part (216) for stitching in conjunction with the stitching plate (40) in the sewing machine. The blade tip (22), the stitching part (216) and the first cutting edge (21) are distributed in sequence. The anti-snagging thread cutter (10) also includes a blade mounting part (30) fixed to the blade body part (20). The outer surface of the blade mounting part (30) is provided with a pressure line avoidance groove (31). The starting pressure line part (216) and the pressure line avoidance groove (31) are arranged opposite each other along the axial direction of the rotary hook. The outer surface of the starting pressure line part (216) is closer to the pressure line piece (40) than the bottom surface of the pressure line avoidance groove (31) facing the pressure line piece (40).

8. A thread-cutting mechanism for preventing thread snagging, comprising a movable main blade, a first thread-cutting drive source (61), a first thread-cutting transmission assembly, and a fixed auxiliary blade (50), wherein the first thread-cutting drive source (61) is connected to the main blade via the first thread-cutting transmission assembly, the main blade can engage with the auxiliary blade (50), and the main blade and the auxiliary blade (50) are distributed inward and outward along a direction away from the rotary hook in the sewing machine, characterized in that: The main moving blade is the anti-snagging wire cutter (10) as described in any one of claims 1-7.

9. A thread-cutting mechanism for preventing thread snagging, comprising a movable main blade, a first thread-cutting drive source (61), a first thread-cutting transmission assembly, and a movable auxiliary blade (50), wherein the first thread-cutting drive source (61) is connected to the main blade and the auxiliary blade (50) via the first thread-cutting transmission assembly, the main blade can engage with the auxiliary blade (50), and the main blade and the auxiliary blade (50) are distributed inward and outward along a direction away from the rotary hook in the sewing machine, characterized in that: The main moving blade is the anti-snagging wire cutter (10) as described in any one of claims 1-7.

10. A thread-cutting mechanism for preventing thread snagging, comprising a movable main blade, a first thread-cutting drive source (61), a first thread-cutting transmission assembly, a movable auxiliary blade (50), a second thread-cutting drive source (62), and a second thread-cutting transmission assembly, wherein the first thread-cutting drive source (61) is connected to the main blade via the first thread-cutting transmission assembly, and the second thread-cutting drive source (62) is connected to the auxiliary blade (50) via the second thread-cutting transmission assembly, wherein the main blade can engage with the auxiliary blade (50), and the main blade and the auxiliary blade (50) are distributed inward and outward along a direction away from the rotary hook in the sewing machine, characterized in that: The main moving blade is the anti-snagging wire cutter (10) as described in any one of claims 1-7.

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