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CN-122013457-A - Upper thread anti-thread-off and thread-lifting method of sewing machine and sewing machine

CN122013457ACN 122013457 ACN122013457 ACN 122013457ACN-122013457-A

Abstract

The invention provides an upper thread anti-thread-dropping and stitch-lifting method of a sewing machine, the sewing machine is provided with a thread passing notch, a first clamping part and a clamping assembly, the clamping assembly is provided with a second clamping part, the method comprises the following steps that before a first needle is lifted, the first thread cutting knife is stopped at a working position A, the thread passing notch is positioned under the needle, the first needle is lifted, the needle moves downwards, the upper thread passes through the thread passing notch and passes through a stitch material, then a rotating shuttle hooks the upper thread, the needle rises to the first thread cutting knife, the upper thread is positioned in the thread passing notch, the first thread cutting knife moves towards the clamping assembly to a working position B, the upper thread passing notch drives the upper thread therein to reach the second clamping part of the clamping assembly, the first clamping part and the second clamping part clamp the upper thread therebetween, the first thread cutting knife stops at the working position B, the needle completes a plurality of subsequent needle stitch-lifting actions, the first thread cutting knife moves to the working position C, and the upper thread is loosened.

Inventors

  • CHEN WEIJIE

Assignees

  • 杰克科技股份有限公司

Dates

Publication Date
20260512
Application Date
20260331

Claims (11)

  1. 1. The upper thread anti-thread-off and thread-up method of the sewing machine is characterized in that a thread passing slot (4) and a first clamping part (5) are arranged on the first thread cutting knife (1), a clamping assembly (3) is further arranged, a second clamping part (301) is arranged on the clamping assembly (3), and the upper thread anti-thread-off and thread-up method comprises the following steps: S1, before a first needle is sewn, stopping the first thread cutter (1) at a working position A, and at the moment, enabling the thread passing slot opening (4) to be positioned right below the needle (6); S2, a first needle is sewn, a machine needle (6) moves downwards, an upper thread passes through the wire slot opening (4) and passes through the sewing material, then a rotating shuttle (7) hooks the upper thread, the machine needle (6) rises to the position above the first thread cutting knife (1), and the upper thread is positioned in the wire slot opening (4); S3, the first thread trimmer (1) moves towards the clamping assembly (3) to a working position B, the thread passing notch (4) drives an upper thread in the thread trimmer to reach a second clamping part (301) of the clamping assembly (3), the first clamping part (5) is close to the second clamping part (301) and clamps the upper thread between the two clamping parts, and the first thread trimmer (1) stops at the working position B; S4, finishing the subsequent stitching actions of a plurality of needles by the machine needle (6); s5, the first thread trimmer (1) moves to the working position C, the first clamping part (5) is separated from the second clamping part (301), and the upper thread is loosened.
  2. 2. The upper thread anti-thread off and seam lifting method according to claim 1, characterized in that the movement of the first thread cutter (1) is driven by a thread cutting motor, the movement of the needle (6) is driven by a main shaft, and the movements of the thread cutting motor and the main shaft are controlled by an electric control system; In the step S1, after receiving a seam starting signal, an electric control system controls a thread cutting motor to run to a phase angle A corresponding to a working position A, so that a first thread cutting knife (1) moves to the working position A and stops; In the step S2, the electric control system enables the needle (6) to rise to a first needle stopping position above the first thread trimmer (1) and stop by controlling the rotation angle theta 1 of the main shaft based on the phase angle A of the operation of the thread trimmer; in the step S3, the electronic control system automatically controls the wire cutting motor to operate to a phase angle B corresponding to the working position B based on the rotation angle θ1 of the spindle, so that the first wire cutting knife (1) moves to the working position B and stops; in the step S4, the electric control system automatically controls the spindle rotation angle theta 2 based on the phase angle B of the thread cutting motor, so that the machine needle (6) finishes the follow-up needle seam lifting actions; In the step S5, the electronic control system automatically controls the wire cutting motor to operate to a phase angle C corresponding to the working position C based on the rotation angle θ2 of the spindle.
  3. 3. The method for preventing and sewing an upper thread from coming off as claimed in claim 1, wherein in the step S3, the moving direction of the first thread trimmer (1) from the working position a to the working position B is opposite to the moving direction when the first thread trimmer (1) hooks the upper thread to trim the upper thread.
  4. 4. The method for preventing needle thread from coming off and starting up as claimed in claim 1, wherein in the step S3, the first thread trimmer (1) is completely kept away from the position right under the starting needle (6) when it is located at the working position B.
  5. 5. The method for preventing the needle thread from coming off and starting the seam according to claim 1, wherein in the step S4, the first thread cutter (1) is completely kept away from the position just below the needle (6) when being located at the working position C, and the thread hooking groove (12) passes through the axis of the needle (6) when the first thread cutter (1) starts to move from the working position C toward the second thread cutter (2) of the thread cutting mechanism.
  6. 6. The method for preventing the upper thread from coming off the thread and being sewn according to claim 1, characterized in that the first clamping part (5) is arranged on the upper surface of the first thread trimmer (1), and in the step S3, the first thread trimmer (1) is inserted below the second clamping part (301) of the clamping assembly (3) when being positioned at the working position B.
  7. 7. The upper thread anti-thread take-off method according to claim 1 or 6, wherein the first clamping part (5) comprises a clamping protrusion of the upper surface of the first thread trimmer (1).
  8. 8. The method for preventing and sewing an upper thread from coming off as claimed in claim 1, wherein in the step S3, the thread passing notch (4) of the first thread trimmer (1) passes through the second clamping portion (301) first, and then the second clamping portion (301) approaches the first clamping portion (5) to clamp the upper thread.
  9. 9. The method for preventing and sewing an upper thread from being separated according to claim 1 or 8, wherein the thread passing slot (4) comprises a threading slot (41) and a guiding slot (42), the first end of the guiding slot (42) is communicated with the threading slot (41), the second end of the guiding slot extends along the direction from the working position B to the working position A, the width of the guiding slot (42) is gradually reduced from the first end to the second end, and in the step S3, the upper thread passing slot (4) drives the upper thread therein to reach the second clamping part (301), and the upper thread moves from the first end to the second end of the guiding slot (42) and is reversed to the first clamping part (5).
  10. 10. The method for preventing the upper thread from being separated from the thread and being sewn according to claim 1 or 8, characterized in that the clamping assembly (3) is provided with a V-shaped notch (302), the V-shaped notch (302) faces to the first thread trimmer (1) located at the working position A, the width of the V-shaped notch (302) gradually decreases along the direction from the working position A to the working position B, and in the step S3, the upper thread passing notch (4) drives the upper thread therein to enter the V-shaped notch (302) and reach the bottom of the notch.
  11. 11. A sewing machine comprising a thread cutting mechanism having a first thread cutter (1) for hooking an upper thread to perform thread cutting, characterized in that a thread take-off prevention thread take-off method according to any one of claims 1 to 10 is adopted to perform a thread take-off operation.

Description

Upper thread anti-thread-off and thread-lifting method of sewing machine and sewing machine Technical Field The invention relates to the technical field of sewing equipment, in particular to an upper thread anti-thread-off and thread-lifting method of a sewing machine and the sewing machine. Background The lock stitch is used as the most common stitch form of the pattern sewing machine, and is widely applied to the sewing processing of products such as clothing, bags, leather products and the like by virtue of the advantages of simple structure, firm sewing and small thread consumption. The stitch forming principle is that after the needle drives the upper thread to pierce the cloth, the rotating shuttle hooks the upper thread to form the thread loop, and the thread loop is tightened by the thread take-up lever mechanism and the bottom thread is pulled into the back of the cloth to interweave and lock the upper thread and the bottom thread, so as to complete the stitch forming. However, the lock stitch has the natural structural limitation that after the first needle penetrates the cloth, an effective thread loop cannot be directly formed in the thread hooking process of the rotating shuttle, and the upper thread is pre-buried in the cloth by the first needle, so that a basic support is provided for the thread loop formation of the second needle. Along with the diversification of cloth materials (such as light and thin chemical fiber, high-elasticity fabric and multi-layer composite fabric) and the complexity of sewing working conditions (high-speed sewing and variable-thickness sewing) in industrial production, the forming stability of the existing lock stitch faces serious challenges that the first needle thread pre-embedded in the cloth is very easy to be pulled out under the action of the traction force of the second needle thread taking-up lever due to loose fiber structure and insufficient friction resistance on the back surface of the cloth, so that the second needle cannot form a complete thread loop, and finally the needle thread-off fault is initiated. The problem of off-line can cause the work piece repair rate to rise greatly, seriously affects the production efficiency, and especially in a mass production scene, has become a key bottleneck for restricting the improvement of the sewing quality and the productivity. To solve the problem of lock stitch needle lifting and thread releasing, various solutions have been proposed in the prior art, but each has certain drawbacks: The parameter adjustment scheme is to enhance the fixing effect of the upper thread by the modes of starting the needle reversing function, setting a starting slow needle or prolonging the length of the starting stitch, and the like. The scheme is simple and convenient to operate, but has the defects that the inverted needle can increase stitch density, the dense cloth pinholes and fiber breakage are easy to cause, the starting slow needle directly reduces the sewing efficiency, the suitability of parameter adjustment is extremely poor, and the sewing requirements of cloth with different thicknesses and materials cannot be met at the same time. The mechanism improvement scheme is that part of the technology adopts an independent stepping motor to drive the middle presser to lift by optimizing the middle presser mechanism, so that the middle presser in the needle lifting stage compresses the cloth in advance, and the upper thread displacement is reduced. Although the needle stability can be lifted to a certain extent in this scheme, the structure transformation is complicated, needs additionally to increase driving motor and electrical system, leads to equipment cost to rise, and just can solve the not hard up problem of cloth, can't fundamentally promote the anti-take-off ability of first needle face line, still has not effectively improved high smoothness surface fabric. The operation and adjustment scheme is to optimize the tension of the upper thread through manual operations such as pressure regulation of the presser foot, impurity cleaning of the shuttle shell, tightness adjustment of the thread clamp and the like. The method relies on experience of operators, has poor stability, is easy to lose effectiveness due to cloth displacement and line tension fluctuation in the high-speed sewing process, and is not suitable for an automatic production line. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an upper thread anti-thread-off and thread-lifting method for a sewing machine, and a sewing machine, which can stably clamp an upper thread after lifting a first needle by controlling the action of a thread cutting mechanism to cooperate with the action of a needle and cooperate with a clamping assembly, thereby avoiding the thread-lifting and thread-lifting problem. In order to achieve the above object, the present invention provides an upper thr