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

Abstract

The utility model provides a kind of for sewing machine's anti-hanging thread thread cutting knife and anti-hanging thread thread cutting mechanism, anti-hanging thread thread cutting knife includes knife main part, the knife tip portion being arranged at the end of knife main part, and all through the thread separation hooking groove and bobbin thread separation groove of knife main part, thread separation hooking groove and bobbin thread separation groove are arranged at the two side edges of knife main part, knife main part has the bobbin thread sliding surface being connected between knife tip portion and bobbin thread separation groove mouth;Anti-hanging thread thread cutting knife is also provided with line blocking protruding portion, line blocking protruding portion and bobbin thread sliding surface face to face distribution along rotating shuttle axial, and the line passing narrow passage is formed between the two, and the mouth of line passing narrow passage is communicated with bobbin thread separation groove.In normal sewing process, the line blocking protruding portion that towards bobbin thread sliding surface protrudes left can narrow the space where thread can be hung, and the thread ring of normal sewing is blocked outside bobbin thread separation groove, and the undesirable hanging thread phenomenon that bobbin thread slides into bobbin thread separation groove in sewing process is prevented, prevent thread from being hung in normal sewing process, and improve sewing performance.

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 sewing machines, which is movably configured on the outer periphery of the rotary hook in a sewing machine;

[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 hook groove and a surface wire dividing groove that penetrate the main body along the thickness direction of the main body. The wire hook groove and the surface wire dividing groove are located at the two sides of the main body along the axial direction of the rotary hook. The outer peripheral surface of the main body has a surface wire sliding surface connecting the opening of the tip and the surface wire dividing groove.

[0008] The anti-snagging wire cutter is also provided with a wire-blocking protrusion. The wire-blocking protrusion and the sliding surface of the top thread are distributed face to face along the axis of the rotary hook, and a wire-passing passage is formed between them. The wire-passing passage is connected to the slot of the top thread dividing groove.

[0009] Furthermore, the outer peripheral surface of the blade body also has a bottom line sliding surface connecting the blade tip and the groove of the dividing line groove. The bottom line sliding surface extends obliquely, moving further away from the blade tip. The outer peripheral surface of the line-blocking protrusion is provided with a line-blocking inclined surface parallel to the bottom line sliding surface. The line-blocking inclined surface is close to the groove of the dividing line groove. The line passage is formed between the bottom line sliding surface and the line-blocking inclined surface.

[0010] Furthermore, the minimum width of the passageway is 0.8mm-1.2mm.

[0011] Furthermore, the inner surface of the blade body facing the rotary hook has an anti-snagging inclined surface on the side of the face thread dividing groove. The anti-snagging inclined surface extends to the face thread sliding surface. The anti-snagging inclined surface is further away from the rotary hook relative to the inner surface of the blade body. The anti-snagging inclined surface is close to the groove opening of the face thread dividing groove. The anti-snagging inclined surface is a chamfered 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 facing the rotary hook is provided with a dividing slope. The dividing slope extends obliquely with the distance from the opening of the dividing hook groove getting closer 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 facing away from the rotary hook has a surface thread receiving portion on the side of the surface thread dividing groove, and one end of the surface thread receiving portion extends to the surface thread dividing groove.

[0014] Furthermore, the outer surface of the blade body facing away from the rotary hook is provided with a first cutting edge for engaging with the auxiliary blade in the sewing machine, and a stitch-starting part for cooperating with the stitch-pressing plate in the sewing machine to press the thread, wherein 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 facing away from the rotary hook 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] When the thread is cut at the end of sewing, the right half of the top thread loop slides smoothly into the top thread divider groove through the thread passage under the action of the anti-snagging thread cutter. However, during normal sewing, the thread-blocking protrusion protruding to the left of the top thread sliding surface narrows the space where the thread can get caught, blocking the thread loop during normal sewing outside the top thread divider groove. This prevents the top thread from sliding into the top thread divider groove during sewing, thus preventing thread snagging during normal sewing and improving sewing performance. Attached Figure Description

[0021] Figure 1 and Figure 2 This is a schematic diagram 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 1 of the anti-snagging and wire-cutting mechanism of this application from different perspectives.

[0023] Figure 5 This is a schematic diagram of the structure of Embodiment 2 of the anti-snagging and wire-cutting mechanism of this application.

[0024] Figure 6 and Figure 7 These are schematic diagrams of the structure of Embodiment 3 of the anti-snagging and wire-cutting mechanism of this application from different perspectives.

[0025] 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 climbing surface 241, second material reduction part 25, second climbing surface 251, third material reduction part 26, third climbing surface 261, thread parting hook 27, thread parting bevel 271, top thread parting groove 28, thread passage 210, thread blocking protrusion 211, thread blocking bevel 2111, top thread sliding surface 212, top and bottom thread sliding surface 213, anti-snagging bevel 214, top thread receiving part 215, seam starting and pressing part 216, seam starting hook groove 217, post-seam thread cutting and receiving part 218. The components include: a thread receiving part 219, a barb part 220, a knife mounting part 30, a thread pressing groove 31, a thread pressing plate 40, an auxiliary knife 50, a first thread cutting drive source 61, a second thread cutting drive source 62, a first thread cutting drive crank 71, a first thread cutting connecting rod 72, a first thread cutting shaft 73, a first thread cutting transmission crank 74, a second thread cutting transmission crank 75, a second thread cutting connecting rod 76, an active knife holder 77, a third thread cutting transmission crank 78, a thread cutting transmission groove 79, an auxiliary knife holder 710, a thread cutting transmission pin 711, a second thread cutting drive crank 712, a third thread cutting connecting rod 713, a second thread cutting shaft 714, a fourth thread cutting transmission crank 715, a fourth thread cutting connecting rod 716, and a suction pipe 80. Detailed Implementation

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] like Figure 3 ,or Figure 5 ,or Figure 6As 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.

[0032] Embodiment of anti-snagging wire cutter 10

[0033] like Figure 3 ,or Figure 5 ,or Figure 6 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.

[0034] like Figure 1 and Figure 2 As 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.

[0035] In particular, such as Figure 1 and Figure 2As shown, the anti-snagging wire cutter 10 is provided with a wire-blocking protrusion 211. The wire-blocking protrusion 211 and the wire-blocking sliding surface 212 on the side edge of the wire-separating groove 28 on the main body of the cutter 20 are distributed face to face along the axis of the rotary hook. The wire-blocking protrusion 211 is distributed on the right side of the wire-separating sliding surface 212. A wire-passing passage 210 communicating with the wire-separating groove 28 is formed between the wire-blocking protrusion 211 and the wire-separating sliding surface 212.

[0036] When the sewing machine finishes sewing and the thread needs to be cut, 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. Driven by the anti-snagging thread cutter 10, the left half of the top thread loop and the bottom thread slide relative to each other along the top and bottom thread sliding surfaces 213 until they slide into the thread separating groove 23 through the opening of the groove. The right half of the top thread loop slides relative to each other along the top thread sliding surface 212 until it slides into the top thread separating groove 28 through the opening of the groove. Then, the anti-snagging thread cutter 10 rotates backward, pulling the bottom thread and top thread in the thread separating groove 23 together toward the auxiliary blade 50 and rotating backward 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 off the bottom thread and top thread drawn out from the thread separating groove 23, thus achieving automatic thread cutting at the end of sewing.

[0037] Therefore, when the sewing process ends and the thread is cut, the right half of the top thread loop slides smoothly into the top thread dividing groove 28 from the thread passage 210 under the action of the anti-snagging thread cutter 10. However, during normal sewing, the thread-blocking protrusion 211 protruding to the left towards the top thread sliding surface 212 can narrow the space where the thread can be caught, blocking the thread loop during normal sewing outside the top thread dividing groove 28, thereby preventing the top thread from sliding into the top thread dividing groove 28 during sewing.

[0038] Furthermore, such as Figure 1 and Figure 2 As 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 extends at an angle to the right and rear starting from the blade tip 22. 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 defective phenomenon of top thread snagging. Preferably, the minimum distance between the thread-blocking protrusion 211 and the top thread sliding surface 212 in the left-right direction (i.e., the minimum width of the thread passage 210) is 0.8mm-1.2mm, preferably 1mm.

[0039] Furthermore, such as Figure 1As shown, the outer peripheral surface of the thread-blocking protrusion 211 has a thread-blocking inclined surface 2111 parallel to the thread sliding surface 212. The thread-blocking inclined surface 2111 is adjacent to the opening of the thread dividing groove 28, and the thread passage 210 is formed between the thread sliding surface 212 and the thread-blocking inclined surface 2111. The solid portion at the front end of the thread-blocking inclined surface 2111 can block the thread outside the thread passage 210 during sewing, preventing the thread from entering during sewing. Furthermore, as... Figure 2 As shown, the inner surface of the blade body 20 has an anti-snagging bevel 214 on the side of the thread dividing groove 28. The anti-snagging bevel 214 is further away from the rotary hook relative to the inner surface of the blade body 20, and is close to the opening of the thread dividing groove 28. Thus, if the thread accidentally gets caught around the anti-snagging bevel 214 during sewing, it is blocked by the inner surface of the blade body 20, preventing the thread loop from being properly sewn from entering the thread dividing groove 28. The anti-snagging bevel 214 is machined on the inner surface of the blade body 20 by chamfering, making it a chamfered surface.

[0040] Furthermore, such as 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 1 As 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] 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.

[0053] Example 1 of the anti-snagging and wire-cutting mechanism

[0054] 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 3 and Figure 4 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.

[0055] In Embodiment 1 of the anti-snagging and wire-cutting mechanism, as follows: Figure 3 and Figure 4As 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.

[0056] Example 2 of the anti-snagging and wire-cutting mechanism

[0057] 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 5 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.

[0058] In Embodiment 2 of the anti-snagging and wire-cutting mechanism, as follows: Figure 5As 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.

[0059] Example 3 of the anti-snagging and wire-cutting mechanism

[0060] 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 6 and Figure 7 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.

[0061] In Embodiment 3 of the anti-snagging and wire-cutting mechanism, such as Figure 6 and Figure 7As 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.

[0062] Furthermore, such as Figure 3 and Figure 4 As shown, or as Figure 5 As shown, or as Figure 6 and Figure 7 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.

[0063] In summary, this utility model effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0064] 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-stopping cutter for a sewing machine, movably configured on the outer periphery of a rotary hook in a sewing machine; The anti-snagging wire cutter 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. 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. The outer peripheral surface of the main body (20) has a surface wire sliding surface (212) connecting the opening of the tip (22) and the surface wire-splitting groove (28). Its features are: The anti-snagging wire cutter (10) is also provided with a wire-blocking protrusion (211). The wire-blocking protrusion (211) and the surface sliding surface (212) are distributed face to face along the axis of the rotary hook, and a wire-passing passage (210) is formed between them. The wire-passing passage (210) is connected to the slot of the surface wire dividing groove (28).

2. 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) also has a bottom line sliding surface (213) connecting the blade tip (22) and the groove of the dividing line groove (23). The bottom line sliding surface (212) extends obliquely, moving further away from the blade tip (22) and further away from the bottom line sliding surface (213). The outer peripheral surface of the line-blocking protrusion (211) is provided with a line-blocking inclined surface (2111) parallel to the line-blocking surface (212). The line-blocking inclined surface (2111) is close to the groove of the dividing line groove (28). The line passage (210) is formed between the line-blocking surface (212) and the line-blocking inclined surface (2111).

3. The anti-snagging thread cutter for a sewing machine according to claim 1 or 2, characterized in that: The minimum width of the passageway (210) is 0.8mm-1.2mm.

4. The anti-snagging thread cutter for a sewing machine according to claim 1, characterized in that: The inner surface of the blade body (20) facing the rotary hook has an anti-snagging inclined surface (214) on the side of the face line dividing groove (28). The anti-snagging inclined surface (214) extends to the face line sliding surface (212). The anti-snagging inclined surface (214) is further away from the rotary hook than the inner surface of the blade body (20). The anti-snagging inclined surface (214) is close to the groove opening of the face line dividing groove (28). The anti-snagging inclined surface (214) is a chamfered surface.

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 dividing hook (27) has a dividing slope (271) on its inner surface facing the rotary hook. The dividing slope (271) extends obliquely so 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 blade body (20) has a face line receiving part (215) on the side of the face line dividing groove (28) facing away from the outer surface of the rotary hook. One end of the face line receiving part (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) facing away from the rotary hook is provided with a first cutting edge (21) for engaging with the auxiliary blade (50) in the sewing machine, and a starting stitching part (216) for cooperating with the stitching plate (40) in the sewing machine to press the stitch. The blade tip (22), the starting 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 blade mounting part (30) has a pressing groove (31) on its outer surface facing away from the rotary hook. The starting pressing part (216) and the pressing groove (31) are arranged opposite each other along the axial direction of the rotary hook. The outer surface of the starting pressing part (216) is closer to the pressing plate (40) than the bottom surface of the pressing groove (31) facing the pressing plate (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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