JPH04347196A - Thread loosening device for tacking machine - Google Patents

Abstract

PURPOSE:To ensure stable residual length of a needle thread after cutting it by a thread cutter by constituting so that a thread loosening substance which is engaged with an engaging part of a thread loosening pin independently opens a thread tension guide in synchronization with thread cutting, especially with the operation of a movable blade of the thread cutter. CONSTITUTION:A thread loosening pin 20 is inserted into a thread tension guide 10, and when the said pin 20 and a thread loosening cam 13 are not in contact, thread tension regulation plates 15 are closed by an energizing force of a tension regulation spring 17 to give tension to a needle thread. A thread loosening substance 22 is supported rotatably centering around a supporting shaft 23 on a mounting root 21 fixed on an arm 11. The said substance 22 has a Y-shaped head and is capable of engaging with an engaging collar part 24 of the said pin 20. To the rear end of the said substance 22, a wire 25 is connected and coupled with the thread cutter. When the wire 25 is pulled, the said substance 22 rotates centering around the supporting shaft 23, presses the engaging collar part 24 of the said pin 20 and a tension regulation plate presser 16 against the energizing force of the said spring 17 thus to loosen the tension of the needle thread with the said plates 15 open.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread loosening device for a basting sewing machine for basting a workpiece cloth.

0002

[Prior Art] Conventionally, in this type of basting sewing machine, a cam installed on the upper shaft presses a thread loosening pin to release the thread tension intermittently during normal sewing, and a special cam is installed during thread trimming. By energizing the solenoid, the pin enters the tension plate and loosens the thread.

0003

[Problems to be Solved by the Invention] However, in the conventional device described above, the pin enters the tone plate and opens using the other end of the tone plate as a fulcrum, so the opening amount of the tone plate is not constant around the entire circumference of the tone plate. Since the needle thread path also changes depending on the feed amount and feeding direction, there is a problem that the remaining length of the needle thread after thread trimming becomes unstable. In addition, since the solenoid is activated by a thread trimming signal, the tension is released before the thread trimming knife captures the upper thread, resulting in the problem that the thread trimming knife may fail to capture the upper thread. . The present invention has been made to solve the above problems, and its purpose is to loosen the thread of a basting sewing machine that can ensure a stable remaining length of needle thread after thread trimming by a thread trimming device. The goal is to provide equipment.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a basting sewing machine equipped with a mechanism for intermittently releasing the thread tension by pressing a thread loosening pin with a cam provided on the upper shaft. In the thread loosening device, the thread loosening pin is provided with an engaging portion, and the thread loosening body that engages with the engaging portion is movably supported by the frame and synchronized with the movement of the movable blade of the thread cutting device during thread cutting. A thread for a basting sewing machine, characterized in that the thread loosening body is operatively connected to a thread trimming device so that the thread loosening body presses an engaging portion of a thread loosening pin and independently releases the thread tension. A loosening device is provided.

[0005]

[Operation] In the thread loosening device of the basting sewing machine constructed as described above, the thread tension is intermittently released by the cam via the thread loosening pin, thereby producing a lightly tight seam unique to basting stitches. During thread trimming, after the movable blade has finished forward movement, the thread loosening body presses the engaging part of the thread loosening pin and releases the thread tension independently of the cam, ensuring a stable remaining length of upper thread after thread trimming. can.

[0006]

Embodiments Examples of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing the thread tension 10. A thread loosening cam 13 is fixed to the upper shaft 12 in the sewing machine arm 11.
Rotates together with 2. The thread tension 10 attached to the sewing machine arm 11 is of a known type and is composed of a thread tension rod 14, a pair of thread tension discs 15, a tension disc holder 16, a tension spring 17, a thread tension nut 18, and the like. A thread loosening pin 20 is inserted into the thread tension 10. When the thread loosening pin 20 is not in contact with the thread loosening cam 13, the thread tension disc 15 is in tension with the tension spring 1.
It is closed by the urging force of 7, and tension is applied to the upper thread. When the thread loosening pin 20 comes into contact with the thread loosening cam 13, the thread loosening pin 20 presses the tension plate holder 16 against the biasing force of the tension spring 17 to release the thread tension plate 15 and release the needle thread tension.

FIG. 2 is a plan view. A thread loosening body 22 is attached to a support shaft 23 on a mounting plate 21 fixed to the sewing machine arm 11.
It is rotatably supported around the center. The tip of the thread loosening body 22 is bifurcated in a Y-shape, and can be engaged with the engagement collar 24 of the thread loosening pin 20. A wire 25 is connected to the rear end of the thread loosening body 22 and connected to a thread cutting device. As shown in FIG. 3, when the wire 25 is pulled, the thread loosening body 2
2 rotates around the support shaft 23 and presses the engagement collar 24 of the thread loosening pin 20 to open the thread tension disc 15 and release the tension on the needle thread.

FIG. 4 is a perspective view showing the drive section of the thread cutting device. A cylindrical thread trimming cam 32 is fixed to a lower shaft 31 under the sewing machine table and rotates together. As shown in FIG. 5, the thread cutting cam 32 has a grooved cam 33 formed on the side circumference for swinging the movable blade, and a thread loosening cam portion 34 formed on the end surface. A solenoid lever 38 is connected to the plunger 36 of the thread cutting solenoid 35 via a solenoid joint 37. The solenoid lever 38 is swingable about a fulcrum 39. A thread cutting shaft 40 is connected to the tip of the solenoid lever 38, and a thread loosening lever 41 is connected to the lower end of the thread cutting shaft 40. Thread loosening lever 41
A roller 42 is provided at the center of the roller 42, and the wire 25 is connected to the tip thereof.

When the thread trimming solenoid 35 is energized by the thread trimming signal, the plunger 36 projects, giving rotational motion to the solenoid lever 38 and pushing up the thread trimming shaft 40. This allows the roller 42 at the center of the thread loosening lever 41 to come into contact with the thread loosening cam portion 34 on the end surface of the thread cutting cam 32.
When the forward movement of the movable blade ends and the thread is captured, the roller 42 comes into contact with the thread loosening cam part 34, rotates the thread loosening lever 41, and pulls the wire 25. As the wire 25 is pulled, the thread loosening body 22 rotates around the support shaft 23 as shown in FIG. Release tension on the upper thread.

0010

[Effects of the Invention] The present invention has the above-mentioned configuration, and a thread loosening mechanism for thread trimming with a separate drive system is added to the intermittent thread loosening mechanism of a basting sewing machine. This has the excellent effect of ensuring a stable needle thread remaining length.

[Brief explanation of drawings]

[Figure 1] Side view showing thread tension,

[Figure 2] Plan view,

[Figure 3] Plan view showing the activated state,

[Figure 4]
A perspective view showing the drive section of the thread cutting device;

FIG. 5 is a perspective view showing a thread trimming cam.

[Explanation of symbols]

12 Upper axis 13 Thread loosening cam 15 Thread tension plate 17 Tune spring 20 Thread loosening pin 22 Thread loosening body 24 Engagement collar 25 Wire 32 Thread trimming cam

Claims (1)

[Claims] 1. A thread loosening device for a basting sewing machine, which is equipped with a mechanism for intermittently releasing the thread tension by pressing a thread loosening pin with a cam provided on an upper shaft, wherein the thread loosening pin is provided with an engaging portion. A thread loosening body that engages with the engaging portion is movably supported by the frame, and the thread loosening body presses the engaging portion of the thread loosening pin in synchronization with the operation of the movable blade of the thread cutting device during thread cutting. A thread loosening device for a basting sewing machine, characterized in that a thread loosening body is operatively connected to a thread cutting device so as to independently release the thread tension.