Nest-free and short thread end-free device for sewing machine

Abstract

The utility model relates to the technical field of sewing machines without bird nests, in particular to a device without bird nests and short thread ends for a sewing machine. The utility model aims to solve a bird nest effect caused by reserved upper thread ends. According to the technical scheme, a driving cutter mechanism and a secondary moving cutter mechanism are respectively arranged below a bottom plate of the sewing machine and are driven by an independent stepping motor, a driving cutter holder and a secondary moving cutter holder are coaxially arranged on a lower shaft left sleeve in an attached mode, a secondary moving cutter of the secondary moving cutter mechanism rotates clockwise, a driving cutter of the driving cutter mechanism rotates anticlockwise, and the driving cutter of the secondary moving cutter mechanism rotates anticlockwise. The driving cutter and the secondary moving cutter move oppositely and are meshed, a sewing thread is cut off under a machine needle, a short thread end is achieved, the fixed cutter mechanism is arranged under a bottom plate of the sewing machine, a fixed cutter of the fixed cutter mechanism is meshed with the secondary moving cutter, an upper thread end is cut off, and no nest is achieved. According to the structure, the reserved upper thread end is cut off, the bird nest-free effect is achieved, the sewing stitch is attractive, meanwhile, after sewing is finished, the cut thread end is short, trimming is avoided, cost is reduced, and efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of no-bird's-nest technology for sewing machines, in particular to a no-bird's-nest and short-thread-end device for sewing machines. Background Art

[0002] At present, in order to prevent the upper thread from flying during the next sewing, ordinary flat-sewing machines will leave an upper thread end of more than 25 mm at the needle after each thread cutting. When sewing again, this thread end is brought below the sewing material. Since the length of the upper thread end cannot form a complete thread loop, a thread ball will be formed on the bottom thread of the sewing material, which is called a "bird's nest". The appearance of the bird's nest seriously affects the beauty of the stitch. At the same time, after sewing, since the thread-cutting position is not directly below the needle, the upper thread end left on the sewing material after thread cutting is too long. Due to the above two reasons, trimming is sometimes required specifically, which increases the production cost.

[0003] The patent number is "2024113298690", and the patent name is "Thread-cutting Method of a Double-acting Knife Thread-cutting Mechanism". It discloses a thread-cutting method realized by two thread-cutting mechanisms. The problems it has are that no bird's nest can be achieved at the start of sewing, the pressure of the blade cannot be independently adjusted when cutting the thread at the end of sewing, the air suction device is far from the direction of the thread end, and it is difficult to recover the thread end. Summary of the Utility Model

[0004] In view of this, in order to solve the bird's nest effect caused by leaving the upper thread end, the utility model provides a no-bird's-nest and short-thread-end device for sewing machines, which cuts off the reserved upper thread end to achieve the no-bird's-nest effect, makes the starting stitch beautiful, and at the same time meets the requirement of short thread ends after sewing, eliminates the process of trimming the thread ends, reduces costs and improves efficiency.

[0005] In order to solve the problems existing in the prior art, the technical solution of the utility model is: a no-bird's-nest and short-thread-end device for sewing machines, which is characterized by comprising a main knife mechanism, a secondary knife mechanism, a fixed knife mechanism and an air suction device. The main knife mechanism and the secondary knife mechanism are respectively arranged under the sewing machine bottom plate and are driven by independent stepping motors. The main knife seat and the secondary knife holder of the main knife mechanism are coaxially and closely arranged on the left sleeve of the lower shaft. The secondary knife of the secondary knife mechanism rotates clockwise, and the main knife of the main knife mechanism rotates counterclockwise. The main knife and the secondary knife move towards each other and mesh to cut off the sewing thread directly below the needle, achieving short thread ends. The fixed knife mechanism is arranged under the sewing machine bottom plate, and the fixed knife of the fixed knife mechanism meshes with the secondary knife to cut off the upper thread end, achieving no bird's nest.

[0006] Further, the secondary cutting tool mechanism is a crank-rocker mechanism, including a driving motor, a secondary cutting tool support, and a secondary cutting tool holder; a driving crank is provided on the motor shaft of the driving motor, and the other end of the driving crank is connected to a right connecting rod; the secondary cutting tool support is arranged at the bottom of the sewing machine base plate, and a secondary cutting tool driving shaft is arranged through the secondary cutting tool support. The two ends of the secondary cutting tool driving shaft are respectively connected to a right driven crank and a left driven crank. The other end of the right connecting rod is connected to the right driven crank, and the other end of the left driven crank is connected to a left connecting rod. The left connecting rod is connected to the secondary cutting tool holder and is arranged on the left sleeve of the lower shaft. A secondary cutting tool is arranged on the secondary cutting tool holder. The secondary cutting tool holder drives the secondary cutting tool to make a circumferential rotational movement around the left sleeve of the lower shaft. A needle receiving hole is arranged near the cutting edge of the secondary cutting tool, and the needle receiving hole on the secondary cutting tool is placed directly below the sewing machine needle; the secondary cutting tool holder is coaxially and adhesively arranged with the primary cutting tool holder of the primary cutting tool mechanism. The primary cutting tool of the primary cutting tool mechanism is arranged on the primary cutting tool holder. The primary cutting tool holder drives the primary cutting tool to make a circumferential rotational movement around the left sleeve of the lower shaft. During cutting, the primary cutting tool and the secondary cutting tool are engaged to achieve cutting.

[0007] Further, the fixed cutting tool mechanism includes a fixed cutting tool seat, a pressure adjusting screw assembly, and a fixed cutting tool; the fixed cutting tool is arranged in the installation groove of the fixed cutting tool seat and is located outside the secondary cutting tool. A pressure adjusting screw assembly is arranged on the upper part of the fixed cutting tool seat, and the pressure of the fixed cutting tool is adjusted by rotating the pressure adjusting screw assembly.

[0008] Further, the air suction device is arranged at the bottom of the base plate, and its air suction port is directly opposite to the rotating hook assembly of the sewing machine. The air suction device is arranged outside the primary cutting tool of the primary cutting tool mechanism.

[0009] Further, the secondary cutting tool is located between the primary cutting tool of the primary cutting tool mechanism and the fixed cutting tool.

[0010] Compared with the prior art, the advantages of the present utility model are as follows:

[0011] 1. The cutting of the present utility model is composed of three mechanisms: a primary cutting tool mechanism, a secondary cutting tool mechanism, and a fixed cutting tool mechanism. The primary cutting tool mechanism and the secondary cutting tool mechanism are respectively driven by independent stepping motors, and at the same time, they cooperate with the fixed cutting tool mechanism to complete cutting. It can not only achieve no bird's nest but also achieve short thread ends, without the need for a special person to trim the thread ends, saving labor and reducing costs.

[0012] 2. The present utility model is provided with an independent air suction device, which immediately sucks away the thread end after the secondary cutting tool and the fixed cutting tool cut off the surface thread end, making the oil pan clean and hygienic. Brief Description of the Drawings

[0013] Figure 1 This is the general assembly drawing provided by the present utility model.

[0014] Figure 2 This is the primary cutting tool mechanism drawing provided by the present utility model.

[0015] Figure 3 This is the diagram of the secondary moving knife mechanism provided by the present utility model.

[0016] Figure 4 This is the diagram of the fixed knife mechanism provided by the present utility model.

[0017] Figure 5 This is the working principle diagram of the "no bird's nest" provided by the present utility model.

[0018] Figure 6 This is the working principle diagram of the "no bird's nest" provided by the present utility model.

[0019] Figure 7 This is the working principle diagram of the short thread end provided by the present utility model.

[0020] Figure 8 This is a schematic diagram of the secondary moving knife holder.

[0021] Figure 9 This is a schematic diagram of the engagement of three blades.

[0022] Reference numerals: 1 - sewing needle, 2 - main moving knife mechanism, 3 - secondary moving knife mechanism, 4 - fixed knife mechanism, 5 - air suction device, 6 - rotary hook assembly, 7 - bottom plate, 8 - surface thread;

[0023] 101 - stepping motor, 102 - driving fork, 103 - driven crank, 104 - transmission shaft, 105 - return spring, 106 - main moving knife crank, 107 - main moving knife, 108 - tangent convex platform, 109 - main moving knife seat, 110 - connecting rod;

[0024] 201 - driving motor, 202 - driving crank, 203 - right connecting rod, 204 - right driven crank, 205 - secondary moving knife support, 206 - secondary moving knife drive shaft, 207 - left connecting rod, 208 - left driven crank, 209 - secondary moving knife, 210 - secondary moving knife holder, 211 - needle holding hole, 212 - left lower shaft sleeve;

[0025] 301 - fixed knife seat, 302 - pressure regulating screw assembly, 302 - 1 - pressure regulating screw, 302 - 2 - locking nut, 303 - fixed knife, 304 - fixed knife edge;

[0026] 501 - air suction port;

[0027] 601 - rotary hook tip. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0029] The utility model provides a device for preventing bird's nests and short thread ends for a sewing machine, which uses three blades for thread cutting, adds a needle accommodating hole on the secondary moving knife, and the mechanism movement is independently driven by a stepping motor to realize the independent reciprocating movement of the secondary moving knife. A fixed knife mechanism is added. During sewing, the secondary moving knife cooperates with the fixed knife. The mechanism is driven by an independent stepping motor. When starting sewing, the secondary moving knife 209 rotates clockwise, and its needle accommodating hole 211 and the fixed knife cut off the surface thread end to realize no bird's nest. After sewing is completed, the main moving knife 107 and the secondary moving knife 209 move towards each other and cut off the sewing thread directly below the sewing needle to realize short thread ends, and the thread ends are sucked away by a suction device.

[0030] Specifically, the following structure is adopted:

[0031] The above-mentioned main moving knife mechanism 1 is as Figure 2 shown, and includes a stepping motor 101, a driving fork 102, a driven crank 103, a transmission shaft 104, a return spring 105, a main moving knife crank 106, a main moving knife 107, a tangent convex platform 108, a main moving knife seat 109 and a connecting rod 110; the stepping motor 101 is fixed at the bottom of the sewing machine, and a driving fork 102 is arranged on its motor shaft. The driving fork 102 is connected to the driven crank 103, and relative movement can be realized between the two. The driven crank 103 is sleeved on the right end of the transmission shaft 104. A return spring 105 and a main moving knife crank 106 are sleeved on the left end of the transmission shaft 104. The main moving knife crank 106 is connected to the main moving knife seat 109 through a connecting rod 110. The main moving knife 107 is arranged on the main moving knife seat 109. The main moving knife seat 109 and the secondary moving knife holder 210 are coaxially and closely arranged on the left sleeve 212 of the lower shaft. The stepping motor 101 drives the main moving knife 107 to realize independent reciprocating movement around the left sleeve 212 of the lower shaft in the circumferential direction through transmission.

[0032] The above-mentioned secondary moving knife mechanism 2 is a crank-rocker mechanism, as Figure 3 、 Figure 8 and Figure 9As shown in the figure, it includes: a drive motor 201, a drive crank 202, a right connecting rod 203, a left connecting rod 207, a right driven crank 204, a left driven crank 208, a secondary cutter support 205, a secondary cutter drive shaft 206, a secondary cutter 209, a secondary cutter holder 210, and a needle accommodating hole 211; a drive crank 202 is provided on the motor shaft of the drive motor 201, and the other end of the drive crank 202 is connected to a right connecting rod 203; the secondary cutter support 205 is arranged at the bottom of the sewing machine base plate 7, a secondary cutter drive shaft 206 is passed through the secondary cutter support 205, and the two ends of the secondary cutter drive shaft 206 are respectively connected to a right driven crank 204 and a left driven crank 208, the other end of the right connecting rod 203 is connected to the right driven crank 204, the other end of the left driven crank 204-1 is connected to the left connecting rod 207, the left connecting rod 207 is connected to the secondary cutter holder 210 and is arranged above the lower shaft left sleeve 211, a secondary cutter 209 is provided on the secondary cutter holder 210, the secondary cutter holder 210 drives the secondary cutter 209 to perform a circumferential rotational movement around the lower shaft left sleeve 212, a needle accommodating hole 211 is arranged near the cutting edge of the secondary cutter 209, and the needle accommodating hole 211 on the secondary cutter 209 is placed directly below the sewing machine needle 4; the secondary cutter holder 210 is coaxially and closely arranged with the main cutter holder 109 of the main cutter mechanism 1, the main cutter 107 of the main cutter mechanism 1 is arranged on the main cutter holder 109, the main cutter holder 109 drives the main cutter 107 to perform a circumferential rotational movement around the lower shaft left sleeve 212, during cutting, the main cutter 107 and the secondary cutter 209 are engaged with each other to achieve cutting; the secondary cutter 209 is located between the main cutter 107 of the main cutter mechanism 1 and the fixed cutter 303, is arranged on the secondary cutter holder 210, and a needle accommodating hole 211 is arranged near its cutting edge. The secondary cutter mechanism 2 is driven by a crank-rocker mechanism, and the drive motor 201 drives the secondary cutter 209 to perform an independent reciprocating movement around the lower shaft left sleeve 212 in the circumferential direction through the mechanism transmission.

[0033] The above fixed cutter mechanism 3 is as Figure 4 shown, and it includes: a fixed cutter seat 301, a pressure adjusting screw assembly 302, and a fixed cutter 303; the fixed cutter 303 is located outside the secondary cutter 209 and is arranged in the installation groove of the fixed cutter seat 301. The fixed cutter 303 of the fixed cutter mechanism 3 is engaged with the secondary cutter 209 to cut off the thread end of the surface thread and achieve no bird's nest. The pressure adjusting screw assembly 302 is arranged on the upper part of the fixed cutter seat 301, and the pressure of the fixed cutter 303 is adjusted by rotating the pressure adjusting screw assembly 302. When the pressure of the fixed cutter 303 needs to be adjusted, first loosen the locking nut 302-2, and then rotate the pressure adjusting screw 302-1. The pressure increases clockwise and decreases counterclockwise. After the pressure adjustment is completed, lock the locking nut 302-2 again, and the pressure adjustment of the fixed cutter 303 is completed.

[0034] The above suction device 5 is arranged at the bottom of the bottom plate 7, and its suction port 501 faces the rotating shuttle assembly 6 of the sewing machine. The suction device 5 is arranged outside the driving knife 107 of the driving knife mechanism 1.

[0035] The working process of the present utility model: Refer to Figure 5 , Figure 6 , Figure 7 as shown in

[0036] Before sewing starts, the needle receiving hole 211 on the driven knife 209 is placed directly below the sewing needle. After sewing starts, the sewing needle 1 moves downward with the sewing thread 8, passes through the needle receiving hole 211. When the sewing needle descends to the lowest point and starts to move upward, when it reaches the thread hooking position of the rotating shuttle 6, the tip 601 of the rotating shuttle hooks all the thread ends of the top thread 8 below the driven knife 209, in the direction close to the suction device 5. When the sewing needle 1 leaves the needle plate by a certain distance, the driven knife 209 starts to drive the thread end of the top thread 8 to rotate clockwise and approaches the fixed knife 303. When the sewing needle 1 is about to rise to the highest point, the needle receiving hole 211 cooperates with the blade 304 to cut off the thread end. At this time, the driven knife 209 continues to rotate clockwise. When the blade of the driven knife 209 is flush with the blade 304 of the fixed knife 303, the driven knife 209 stops moving. After the thread end of the top thread 8 is cut off, the suction device 5 sucks away the thread end through the suction port 501, and the no-nest action is completed.

[0037] Refer to Figure 6 , when sewing ends and thread cutting is required, the driving motor 101 drives the driving knife 107 to rotate clockwise, and the driving motor 201 drives the driven knife 209 to rotate counterclockwise. When the tangent convex platform 108 of the driving knife 107 and the blade of the driven knife 209 reach directly below the sewing needle at the same time, they mesh with each other to complete thread cutting, and the short thread end action is completed.

[0038] The above are only the preferred embodiments of the present utility model and are not used to limit the protection scope of the present utility model. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present utility model, several improvements and refinements made to it shall be regarded as within the protection scope of the present utility model.

Claims

1. A device for a sewing machine without bird's nests and short thread ends, characterized in that, It includes a main cutting knife mechanism (1), a secondary cutting knife mechanism (2), a fixed knife mechanism (3) and a suction device (5). The main cutting knife mechanism (1) and the secondary cutting knife mechanism (2) are respectively arranged under the sewing machine base plate (7) and are driven by independent stepping motors. The main cutting knife seat (109) and the secondary cutting knife holder (210) are coaxial and are arranged in contact with each other above the left sleeve of the lower shaft (212). The secondary cutting knife (209) of the secondary cutting knife mechanism (2) rotates clockwise, and the main cutting knife (107) of the main cutting knife mechanism (1) rotates counterclockwise. The main cutting knife (107) and the secondary cutting knife (209) move towards each other and mesh to cut the sewing thread directly below the sewing needle, achieving short thread ends. The fixed knife mechanism (3) is arranged under the sewing machine base plate (7), and the fixed knife (303) of the fixed knife mechanism (3) meshes with the secondary cutting knife (209) to cut the thread end of the surface thread, achieving no bird's nest.

2. The no-bird's nest and short thread-end device for a sewing machine according to claim 1, wherein The secondary cutting knife mechanism (2) is a crank-rocker mechanism, which includes a driving motor (201), a secondary cutting knife support (205) and a secondary cutting knife holder (210). A driving crank (202) is arranged on the motor shaft of the driving motor (201), and the other end of the driving crank (202) is connected with a right connecting rod (203). The secondary cutting knife support (205) is arranged at the bottom of the sewing machine base plate (7). A secondary cutting knife driving shaft (206) is arranged through the secondary cutting knife support (205). The two ends of the secondary cutting knife driving shaft (206) are respectively connected with a right driven crank (204) and a left driven crank (208). The other end of the right connecting rod (203) is connected with the right driven crank (204), and the other end of the left driven crank (208) is connected with a left connecting rod (207). The left connecting rod (207) is connected with the secondary cutting knife holder (210) and is arranged above the left sleeve of the lower shaft (212). A secondary cutting knife (209) is arranged on the secondary cutting knife holder (210). The secondary cutting knife holder (210) drives the secondary cutting knife (209) to make a circumferential rotational movement around the left sleeve of the lower shaft (212). A needle accommodating hole (211) is arranged near the cutting edge of the secondary cutting knife (209). The needle accommodating hole (211) on the secondary cutting knife (209) is placed directly below the sewing machine needle (4). The secondary cutting knife holder (210) is coaxial and is arranged in contact with the main cutting knife seat (109) of the main cutting knife mechanism (1). The main cutting knife (107) of the main cutting knife mechanism (1) is arranged on the main cutting knife seat (109). The main cutting knife seat (109) drives the main cutting knife (107) to make a circumferential rotational movement around the left sleeve of the lower shaft (212). When cutting, the main cutting knife (107) and the secondary cutting knife (209) mesh with each other to achieve cutting.

3. The no-bird's nest and short thread-end device for a sewing machine according to claim 1 or 2, characterized in that, The fixed knife mechanism (3) includes a fixed knife seat (301), a pressure adjusting screw assembly (302) and a fixed knife (303). The fixed knife (303) is arranged in the installation groove of the fixed knife seat (301) and is located outside the secondary cutting knife (209). A pressure adjusting screw assembly (302) is arranged on the upper part of the fixed knife seat (301). Rotating the pressure adjusting screw assembly (302) can adjust the pressure of the fixed knife (303).

4. The no-bird's nest and short thread-end device for a sewing machine according to claim 3, characterized in that, The air suction device (5) is arranged at the bottom of the bottom plate (7), and its air suction port (501) faces the rotating hook assembly (6) of the sewing machine. The air suction device (5) is arranged outside the driving knife (107) of the driving knife mechanism (1).

5. The non-bird's nest and short thread end device for a sewing machine according to claim 4, characterized in that, The secondary driving knife (209) is located between the driving knife (107) of the driving knife mechanism (1) and the fixed knife (303).

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