Thread trimming structure of sewing machine

Abstract

The utility model provides a thread trimming structure of a sewing machine, and belongs to the technical field of machinery. The sewing machine solves the problem that thread ends generated after sewing starting and thread trimming of an existing sewing machine easily fall into a machine shell to form accumulation. The sewing machine comprises a machine frame, an air suction pipe and a needle plate arranged on the machine frame, the thread trimming structure comprises a first thread trimming mechanism and a second thread trimming mechanism, the first thread trimming mechanism comprises a first fixed cutter and a first movable cutter which are fixed on the machine frame, a thread hooking hole is formed in the first movable cutter, and a thread pressing piece is further arranged on the machine frame. The thread pressing piece is provided with a thread pressing part located below the first movable cutter, the thread pressing part is opposite to a pipe opening of the air suction pipe, the thread pressing piece has elasticity, and the thread pressing part can abut against the first movable cutter under the action of the elastic force. The thread pressing piece can press an upper thread on the thread hooking hole of the first movable cutter in an abutting mode, the upper thread is in a tensioned state, thread residues generated after thread trimming can be accurately captured by the air suction pipe, accumulation of the thread residues in the machine shell is avoided, and regular cleaning is not needed.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical technology and relates to a thread-cutting structure for a sewing machine. Background Technology

[0002] The thread trimming mechanism is a crucial component commonly used in sewing machines. Its main functions are to catch and cut the thread end of the top thread during the initial stitching process, and to cut the top and bottom threads after sewing is complete. To ensure shorter thread ends after sewing, existing sewing machine thread trimming mechanisms typically include two sets of trimming mechanisms, allowing for a secondary trimming of the thread end after the initial stitching.

[0003] For example, Chinese patent application (application number: 202211431547.8) discloses a thread-cutting device for a sewing machine. The thread-cutting device includes a first thread-cutting mechanism and a second thread-cutting mechanism. The first thread-cutting mechanism includes a first thread-cutting drive source, an active blade, and a first transmission unit. The active blade has a hook groove and is distributed below the needle plate. The first thread-cutting drive source is connected to the active blade through the first transmission unit. The second thread-cutting mechanism includes a second thread-cutting drive source, a first and a second cutting edge fixed on the bottom surface of the needle plate and distributed on both sides of the needle hole, a sliding blade movably mounted on the bottom surface of the needle plate, and a second transmission unit. The second thread-cutting drive source is connected to the sliding blade through the second thread-cutting unit and drives the sliding blade to move along the parallel distribution direction of the first and second cutting edges. The sliding blade has an avoidance groove and a first and a second movable cutting edge arranged side by side along its moving direction. The first and the second movable cutting edges are disposed in the avoidance groove. When the sewing machine begins to sew, the sliding blade moves to engage the first movable cutting edge with the first cutting edge, cutting the top thread end at the start of the sewing. When sewing ends, the active blade moves in conjunction with the fixed blade to cut the thread (top and bottom thread). Then, the sliding blade moves in the opposite direction to engage the second movable cutting edge with the second cutting edge, achieving a second cut and further cutting the top thread end on the fabric, ensuring that the cut top thread end is shorter.

[0004] However, the above-mentioned thread cutting device has the following defects: When starting to sew, although the active blade moves the thread end in the hook groove to the suction port of the suction nozzle, the thread is in a loose state and floating inside the machine housing at this time. After the thread is cut by the second thread cutting mechanism after the set number of stitches for starting to sew, the thread end produced after cutting is difficult to be sucked up by the suction port, and will fall into the machine housing and accumulate, affecting the operation of other components. It needs to be cleaned regularly, which makes it inconvenient to use. Summary of the Invention

[0005] The purpose of this utility model is to address the aforementioned problems in existing technologies by proposing a thread-cutting structure for sewing machines. The technical problem to be solved by this utility model is: how to solve the problem that the thread ends generated after the sewing machine starts cutting the thread easily fall into the machine casing and accumulate.

[0006] The objective of this utility model can be achieved through the following technical solution: a thread-cutting structure for a sewing machine, the sewing machine including a frame, a suction pipe and a needle plate disposed on the frame, the thread-cutting structure including a first thread-cutting mechanism and a second thread-cutting mechanism disposed at the bottom of the needle plate, the first thread-cutting mechanism including a first fixed blade fixed on the frame and a first movable blade movable relative to the first fixed blade, the first movable blade having a thread-hooking hole, characterized in that the frame is further provided with a thread-pressing plate, the thread-pressing plate having a thread-pressing part located below the first movable blade, the thread-pressing part being opposite to the opening of the suction pipe, the thread-pressing plate being elastic, and the thread-pressing part being able to abut against the first movable blade under the action of elastic force.

[0007] This sewing machine, through the setting of the pressure plate, after the initial stitch is completed and the thread is hooked, when the first moving blade returns to its original position and moves the thread end in the hook hole to the suction pipe, the pressure part of the pressure plate is opposite to the hook hole and the opening of the suction pipe. Under the action of elastic force, the thread can be pressed against the hook hole of the first moving blade, so that the thread is in a taut state. After the number of stitches is set, the thread is cut by the second thread cutting mechanism. Since the generated thread end is limited in the hook hole, it can be accurately captured by the suction pipe and sucked away by the negative pressure of the suction pipe, avoiding the accumulation of thread end in the machine casing. It does not require regular cleaning, greatly improving the ease of operation, and also ensuring the normal operation of other components.

[0008] In the thread-cutting structure of the sewing machine described above, the pressure plate is an arc-shaped piece, and the arc-shaped arched surface of the pressure plate faces the first moving blade. The arc-shaped design of the pressure plate reduces the contact area between the pressure plate and the first moving blade, allowing the thread to be tensioned and held within the hook hole, directly opposite the opening of the suction pipe, after being cut. This makes it easier for the thread end to be sucked away by the suction pipe after thread cutting.

[0009] In the thread-cutting structure of the sewing machine described above, the pressure plate further includes a sheet-shaped connecting part for connection with the machine frame, and a V-shaped elastic part located between the connecting part and the pressure plate. The elastic part provides elastic deformation force, causing the pressure plate to tend to press against the first moving blade, thereby tensioning the top thread within the hook hole, making it easier for the thread end to be sucked away by the suction pipe after thread cutting.

[0010] In the thread-cutting structure of the sewing machine described above, the second thread-cutting mechanism includes a second moving blade and a second fixed blade. The needle plate includes a plate body and a mounting bracket. The second fixed blade is fixed to the bottom of the plate body. The mounting bracket and the plate body together form an elongated sliding groove. The second moving blade is elongated and one end passes through the sliding groove, allowing it to slide within it. The sliding groove is formed by the cooperation of the mounting bracket and the plate body, and the second moving blade passes through the sliding groove, resulting in smoother operation.

[0011] In the thread-cutting structure of the sewing machine described above, the lower surface of the plate has a stepped groove, and the mounting bracket is embedded in the stepped groove and fixed to the plate. The lower surface of the mounting bracket is flush with the lower surface of the plate. Through the above design, the entire needle plate is based on the plate, and the overall volume of the mounting bracket is relatively small. The structure of the stepped groove ensures that the lower surfaces of both remain flush after installation and fixation, resulting in better fit and connection stability, and smaller assembly errors.

[0012] In the thread-cutting structure of the sewing machine described above, a mounting groove is provided at the bottom of the stepped groove. The second fixed blade is plate-shaped and fixed within the mounting groove, with its lower surface flush with the bottom of the stepped groove. This arrangement ensures the second fixed blade is fixed inside the needle plate, resulting in a more compact overall structure, better fit, and higher stability. Furthermore, since both the second moving blade and the second fixed blade are located inside the needle plate, closer to the fabric, the thread ends remaining on the fabric after cutting are shorter.

[0013] In the thread-cutting structure of the sewing machine described above, the second moving blade has a first cutting edge and a second cutting edge. Both the first and second cutting edges are elongated and distributed along the length of the second moving blade. A first cutting edge is located at one end of the first cutting edge, and a second cutting edge is located at one end of the second cutting edge. The first and second cutting edges are arranged adjacent to each other with opposite blade orientations. Both the first and second cutting edges can cooperate with the cutting edge of the second fixed blade to cut the thread. The first cutting edge is used to cut the thread end at the beginning of the sewing process, and the second cutting edge is used to perform a secondary cut on the thread end on the fabric after the thread cutting is completed by the first thread-cutting mechanism at the end of the sewing process, resulting in a shorter thread end remaining on the fabric.

[0014] Compared with existing technologies, the thread-cutting structure of this sewing machine has the following advantages:

[0015] 1. Through the design of the pressure plate, after the stitching is completed, the top thread can be pressed against the stitching hole of the first moving knife, so that the top thread is in a taut state. After the stitches are cut after the set number of stitches for the start-up, the resulting thread ends can be accurately captured by the suction pipe and sucked away by the negative pressure of the suction pipe, avoiding the accumulation of thread ends in the machine casing. This eliminates the need for regular cleaning, greatly improves the ease of operation, and also ensures the normal operation of other components.

[0016] 2. The needle plate adopts a split design of the plate body and the mounting frame, and the second moving knife and the second fixed knife are installed inside the needle plate, which is closer to the fabric, so that the thread left on the fabric after cutting is shorter. Attached Figure Description

[0017] Figure 1 This is a partial structural diagram of the sewing machine of this application.

[0018] Figure 2 This is a partial structural diagram of the wire-cutting mechanism of this application.

[0019] Figure 3 This is a cross-sectional view of the thread-cutting mechanism of this application when the first stitch is being sewn.

[0020] Figure 4 This is a cross-sectional view of the thread-cutting mechanism of this application when it is reset after the first stitch.

[0021] Figure 5 This is a 3D view of the pressure plate.

[0022] Figure 6 This is a 3D view of the first surgical procedure.

[0023] Figure 7 It is a 3D diagram of the needle plate.

[0024] Figure 8 This is an exploded structural diagram of the needle plate, the second moving blade, and the second fixed blade.

[0025] In the diagram, 1 is the frame; 2 is the needle; 3 is the needle plate; 3a is the plate body; 3a1 is the stepped groove; 3a2 is the mounting groove; 3b is the mounting bracket; 3c is the sliding groove; 4 is the suction pipe; 5 is the first thread cutting mechanism; 5a is the first moving blade; 5a1 is the hook hole; 5b is the first fixed blade; 6 is the second thread cutting mechanism; 6a is the second moving blade; 6a1 is the first cutting edge; 6a2 is the second cutting edge; 6b is the second fixed blade; 7 is the thread pressing plate; 7a is the thread pressing part; 7b is the connecting part; 7c is the V-shaped elastic part. Detailed Implementation

[0026] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0027] like Figure 1-6 As shown, this sewing machine includes a frame 1, a suction pipe 4, and a needle plate 3 mounted on the frame 1. The thread cutting structure includes a first thread cutting mechanism 5 and a second thread cutting mechanism 6 mounted on the bottom of the needle plate 3. The first thread cutting mechanism 5 includes a first fixed blade 5b fixed on the frame 1 and a first movable blade 5a that can move relative to the first fixed blade 5b. The first movable blade 5a has a thread hook hole 5a1.

[0028] Specifically, such as Figure 2 and 5 As shown, the frame 1 is also provided with a pressure plate 7. The pressure plate 7 has a sheet-shaped connecting part 7b for connecting with the frame 1, a pressure part 7a located below the first moving blade 5a, and a V-shaped elastic part 7c located between the connecting part 7b and the pressure part 7a. The pressure part 7a is opposite to the opening of the suction pipe 4. The pressure part 7a is an arc-shaped sheet. The arc-shaped arched surface of the pressure part 7a is opposite to the first moving blade 5a. Under the action of the elastic force of the elastic part, the pressure part 7a can abut against the first moving blade 5a.

[0029] Furthermore, such as Figure 7 and 8 As shown, the needle plate 3 includes a plate body 3a and a mounting bracket 3b. The plate body 3a has needle holes, and the lower surface of the plate body 3a has a stepped groove 3a1. The mounting bracket 3b is embedded in the stepped groove 3a1 and fixed to the plate body 3a. The lower surface of the mounting bracket 3b is flush with the lower surface of the plate body 3a. The mounting bracket 3b and the bottom wall of the stepped groove 3a1 together form a long sliding groove 3c. An installation groove 3a2 is provided at the bottom of the stepped groove 3a1. The second wire cutting mechanism 6 includes a second moving blade 6a and a second fixed blade 6b. The second fixed blade 6b is plate-shaped and fixed in the installation groove 3a2. The lower surface of the second fixed blade 6b is flush with the bottom of the stepped groove 3a1. The second moving blade 6a is a long plate-shaped blade with one end passing through the sliding groove 3c and can slide within the sliding groove 3c. The second moving blade 6a has a first cutting edge 6a1 and a second cutting edge 6a2. Both the first cutting edge 6a1 and the second cutting edge 6a2 are elongated and distributed along the length of the second moving blade 6a. The first cutting edge 6a1 has a first cutting edge at one end edge, and the second cutting edge 6a2 has a second cutting edge at one end edge. The first cutting edge and the second cutting edge are arranged adjacent to each other and the cutting edges face opposite directions. Both the first cutting edge and the second cutting edge can cooperate with the cutting edge of the second fixed blade 6b to cut the wire.

[0030] When the sewing machine starts working, the first moving blade 5a is in the initial position, and the hook hole 5a1 on the first moving blade is opposite to the opening of the suction pipe 4. When the sewing machine starts sewing, the first moving blade 5a is controlled to rotate clockwise by an angle so that the hook hole 5a1 on the first moving blade 5a is directly below the needle drop hole of the needle plate 3, such as... Figure 8As shown. The first stitch begins, with the needle 2 passing downwards through the needle drop hole, the second cutting edge 6a2 of the second moving blade 6a, and the hook hole 5a1 of the first moving blade 5a. After cooperating with the rotary hook to complete the hooking action, the needle 2 moves upwards, controlling the first moving blade 5a to rotate counterclockwise to reset. The suction pipe 4 is then activated. Figure 4 As shown. At this time, the first moving blade 5a moves together with the thread end in the hook hole 5a1 to the opening of the suction pipe 4. The thread clamping plate clamps the free end of the thread end in the hook hole 5a1, so that the thread is in a taut state. The suction pipe 4 maintains the suction state, and the sewing machine continues to sew the set number of stitches. Then, the second moving blade 6a is controlled to move to the right, so that the second blade of the second moving blade 6a engages with the blade of the second fixed blade 6b, cutting off the thread end located in the second blade opening 6a2. The cut thread end is limited in the hook hole 5a1 by the thread pressing plate 7, and can be accurately captured by the suction pipe 4 and sucked away by the negative pressure of the suction pipe 4, avoiding the accumulation of thread ends in the machine casing, eliminating the need for regular cleaning, greatly improving the ease of operation, and also ensuring the normal operation of other components. The suction pipe 4 stops running, thus completing the sewing and thread cutting action and preventing the formation of bird nest-like tangles of thread.

[0031] The sewing machine continues its sewing work. The needle 2 passes through the needle hole and the first cutting edge 6a1 of the second moving blade 6a in sequence, engaging with the bobbin thread to form a sewing path on the fabric. After completing the sewing work, the first moving blade 5a is controlled to rotate clockwise until it engages with the first fixed blade 5b, cutting the top thread and bobbin thread. The top thread in the needle 2 is pulled upwards from the fabric. Due to the thickness of the needle plate 3 and the normal working space between the needle plate 3 and the first thread cutting mechanism 5, a certain length of top thread and bobbin thread ends will remain on the fabric. The second moving blade 6a is controlled to move to the left and in the opposite direction, so that the first cutting edge of the second moving blade 6a engages with the second fixed blade 6b, cutting the top thread and bobbin thread ends located in the needle hole and the first cutting edge 6a1, achieving secondary thread cutting. This results in shorter top thread and bobbin thread ends remaining on the fabric, improving the sewing quality of the sewn product.

[0032] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0033] Although this document frequently uses terms such as frame 1, needle 2, needle plate 3, plate body 3a, stepped groove 3a1, mounting groove 3a2, mounting bracket 3b, sliding groove 3c, suction pipe 4, first thread cutting mechanism 5, first moving blade 5a, hook hole 5a1, first fixed blade 5b, second thread cutting mechanism 6, second moving blade 6a, first cutting edge 6a1, second cutting edge 6a2, second fixed blade 6b, pressure plate 7, pressure part 7a, connecting part 7b, and elastic part 7c, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model.

Claims

1. A thread-cutting structure for a sewing machine, the sewing machine comprising a frame (1), a suction pipe (4), and a needle plate (3) disposed on the frame (1), the thread-cutting structure comprising a first thread-cutting mechanism (5) and a second thread-cutting mechanism (6) disposed at the bottom of the needle plate (3), the first thread-cutting mechanism (5) comprising a first fixed blade (5b) fixed on the frame (1) and a first movable blade (5a) movable relative to the first fixed blade (5b), the first movable blade (5a) having a thread hook hole (5a1), characterized in that, The frame (1) is also provided with a pressure plate (7), which has a pressure part (7a) located below the first moving blade (5a). The pressure part (7a) is opposite to the opening of the suction pipe (4). The pressure plate (7) is elastic, and the pressure part (7a) can abut against the first moving blade (5a) under the action of elastic force.

2. The thread-cutting structure of the sewing machine according to claim 1, characterized in that, The pressing part (7a) is an arc-shaped piece, and the arc-shaped arched surface of the pressing part (7a) is opposite to the first moving blade (5a).

3. The thread-cutting structure of the sewing machine according to claim 1 or 2, characterized in that, The pressure plate (7) further includes a sheet-shaped connecting part (7b) for connecting to the frame (1), and a V-shaped elastic part (7c) located between the connecting part (7b) and the pressure plate (7a).

4. The thread-cutting structure of the sewing machine according to claim 1 or 2, characterized in that, The second wire cutting mechanism (6) includes a second moving blade (6a) and a second fixed blade (6b). The needle plate (3) includes a plate body (3a) and a mounting bracket (3b). The second fixed blade (6b) is fixed to the bottom of the plate body (3a). A long sliding groove (3c) is formed between the mounting bracket (3b) and the plate body (3a). The second moving blade (6a) is long and one end passes through the sliding groove (3c) and can slide in the sliding groove (3c).

5. The thread-cutting structure of the sewing machine according to claim 4, characterized in that, The lower plate surface of the plate (3a) has a stepped groove (3a1), and the mounting bracket (3b) is embedded in the stepped groove (3a1) and fixed to the plate (3a). The lower surface of the mounting bracket (3b) is flush with the lower plate surface of the plate (3a).

6. The thread-cutting structure of the sewing machine according to claim 5, characterized in that, The bottom of the stepped groove (3a1) is provided with an installation groove (3a2). The second fixed blade (6b) is plate-shaped and fixed in the installation groove (3a2). The lower plate surface of the second fixed blade (6b) is flush with the bottom of the stepped groove (3a1).

7. The thread-cutting structure of the sewing machine according to claim 4, characterized in that, The second moving blade (6a) has a first cutting edge (6a1) and a second cutting edge (6a2). Both the first cutting edge (6a1) and the second cutting edge (6a2) are elongated and distributed along the length of the second moving blade (6a). The first cutting edge (6a1) has a first cutting edge at one end edge, and the second cutting edge (6a2) has a second cutting edge at one end edge. The first cutting edge and the second cutting edge are arranged adjacent to each other and the cutting edges face opposite directions. Both the first cutting edge and the second cutting edge can cooperate with the cutting edge of the second fixed blade (6b) to cut the wire.

Images