High precision thread trimming device and method for embroidery machine

[0017] Such as Figure 1 to 4 The thread trimming device of an embroidery machine with high-precision trimming is shown, which includes a hook knife driving device located on the upper side of the needle plate 7 and a thread trimming device located on the lower side of the needle plate. The hook knife driving device includes a hook knife motor 16 The outer periphery of the drive shaft of the motor 16 is provided with a position sensor 17 and an eccentric wheel 22. The eccentric wheel 22 is connected by a roller to a pendulum rod 18 with a sliding groove at one end. The pendulum rod 18 is provided with a fixed shaft 23 connected to the motor base, and the pendulum rod 18 The other end is connected to a pull rod driving the hook knife 1 through a connecting rod 19. The knife hook motor 16 is installed on the bottom surface of the cross beam of the embroidery machine, and the swing rod 18 swings horizontally. The preferred technical structure is that the swing rod 18 and the connecting rod 19 are connected by a connecting block 20, the connecting block 20 is provided with front and rear adjusting grooves, and the front and rear adjusting grooves are connected with the swing rod 18, and the connecting block 20 is also provided with upper and lower adjusting pins 21 , The upper and lower adjusting pin 21 cooperates with the connecting rod 19. The connecting rod 19 is connected with a pull rod for controlling the hook knife 1, which realizes the adjustment of the up and down and front and back positions of the pull rod, and also achieves the adjustment of the up and down and front and rear positions of the hook knife 1.

[0018] The thread cutting device includes a rotary hook 6 with a bottom thread built-in. The side of the rotary hook 6 is provided with a thread hook 5 and scissors. The bottom thread in the rotary hook 6 is cut and placed on the bottom thread support frame 14. The rotary hook 6 is installed on the shuttle box 15. The bobbin thread support frame 8 and the scissors installation module 13 are respectively installed on the shuttle box 15. The fixed knife 3 and the movable knife 4 are respectively provided on the scissors installation module 13, and the movable knife 4 passes through the rotating shaft. 10 and the rotating shaft connecting rod 9 are connected to the scissors pull rod 11, and the scissors pull rod 11 is sleeved with a spring and a fixing bracket 12, so that the scissors can be opened and closed under the control of the scissors pull rod 11. The installation method of the scissors installation module greatly improves the installation efficiency and reduces the installation space.

[0019] As a further technical structure, the wire hook 5 is driven to rotate by an electromagnet and is installed on the wire hook installation module. The wire hook installation module 8 is connected to the scissors installation module 13, which further improves installation efficiency and reduces installation space.

[0020] A thread trimming method for embroidery machines with high-precision thread trimming. The needle 2 of the embroidery machine drives an upper thread through the cloth surface on the needle plate to form two upper threads. The two upper threads pass through the shuttle of the rotary hook 6. The tips separate and drive the upper thread to rotate to form a loop at the thread hook 5, the upper thread on the right side of the thread hook 5 is pulled by the hook knife 1, and the hook knife 1 moves back to the stop position to determine the two strands of the upper thread under the cloth. Length, and then determine the cutting position of the scissors relative to a strand of upper thread and bottom thread, and accurately determine the cutting length.

[0021] The feed and retreat start signal of the hook tool 1 is controlled by the rotation angle of the main shaft of the embroidery machine, and the stop position of the hook tool moving back is determined by the position sensor 17 on the outer circumference of the hook tool motor drive shaft, which further improves the position accuracy of the hook tool, that is, the precision of thread cutting. The hook knife 1 pulls the upper thread on the cloth surface to move back to determine the length of the two upper threads under the cloth. After the hook knife returns to the position, there will be a pause, and then the upper thread is clamped by the upper thread clamping mechanism of the embroidery machine , To realize the fixed position of the upper thread, the upper thread clamping mechanism of the embroidery machine can adopt the existing traditional clamping mechanism. In order to achieve multiple trimming lengths, the retracting position of the hook 1 is divided into 1 to 8 to achieve eight trimming lengths. As a specific implementation manner, 8 kinds of tool hook positions are realized by 1 to 8 position sensors 17. Of course, the number of hook positions can be set as required.

[0022] As a further technical method, in the thread trimming method, the motion signals of the embroidery machine needle, scissors, hook knife, and thread hook are all controlled by the rotation angle of the embroidery machine's main shaft.