JPH0333324Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Field of Application] The present invention relates to a thread tension device that can adjust the thread tension to an appropriate level according to the sewing characteristics of each part in a cycle overlock sewing machine for forming buttonholes. [Prior Art] FIG. 6 is an explanatory diagram of a sewing pattern for a sleep hole for a button. P1 and P2 are the first and second
The parallel overlocking parts, L1 and L2 are the first and second parts, respectively.
The bar tacking part, M is a female cutting part. The sewing order is as follows: from the crease cutoff state (upper shaft stopped), start rotating the first parallel part P1 hidden by the second bar tacking part L2 at the start point S at low speed (referred to as P1 _s ), and then At high speed rotation, the same first parallel part P1 → first bar-tacking part 1 → second parallel part P2 → second bar-tacking part L
Sewing is performed in the order of 2, and the sewing speed is set to low speed near the end point E of the second bar tacking portion (referred to as L2 _s ), and the M portion is cut with a scalpel to complete the formation of the buttonhole. When sewing as described above, each bar tacking part L
1. L2 is a whip stitch (normal stitch), and
Since each parallel part P1 and P2 must be sewn with purl stitches, the sewing characteristics of each
Additionally, it is necessary to adjust the tension of the upper thread and lower thread depending on whether the sewing machine is rotating at low or high speed. Two examples of conventional techniques for controlling this kind of thread tension are:
Shown in FIGS. 3 and 4. FIG. 3 shows an example having two thread tension devices 10 and 5, a first and second thread tension device, and FIG. 4 shows an example having three thread tension devices (first, second, and third thread tension devices). 17, 13, and 20, respectively, are perspective views of essential parts. Further, FIG. 5 is an exploded perspective view showing, as an example, the structure of the second thread tension device 5 in the example shown in FIG. 3. First, FIG. 3 will be explained. A thread lifting notch (not shown) on the cloth feed cam (not shown) causes the thread loosening push rod 1 to move when sewing the first and second bar tacks L1 and L2, and when the sewing machine is shut off (the upper shaft rotation is stopped). Moving upward, the second thread tension 5 is moved to the pin 2 via the levers 2, 3 and the thread lifting arm 4.
1 (FIG. 5) is pushed in the axial direction of the arrow A by the cam shape of the tip of the thread lifting arm 4, and the tip of the pin 21 pushes the thread tension disc presser 24, thereby releasing the spring of the thread tension spring 25. The force is restricted and the thread tension disc 22
and 23 are in a state where they are not subjected to spring pressure, and the tension in the thread between them is zero. In Figure 5, 2
6 is a thread tension rod stand, 27 is a thread take-up spring, and 28 is a thread tension rod. When one buttonhole has been formed and the upper shaft rotation of the sewing machine stops, the thread loosening link 6 (Fig. 3) moves in the direction of arrow B, and the starting safety arm (not shown) that operates when the buttonhole is cut off moves in the direction of arrow B. By doing so, each lever
7, 8 and the abutment plate 9 interlock to make the thread tension of the first thread tension 10 zero, similar to the mechanical operation of the second thread tension 5. Next, the three first, second and third thread tensions 26,
The example shown in FIG. 4 using 13 and 20 will be explained.
A thread lifting notch (not shown) on the cloth feed cam (not shown) allows the thread loosening push rod 11 to be moved upward when the first and second bar tacks L1 and L2 (and when the upper shaft rotation of the sewing machine is stopped (cut off)). When the thread is moved to , the arm 12 moves together, and the second thread tension 13 has the same structure as that shown in FIG. 5, and the thread tension at this portion becomes zero. Furthermore, when the sewing machine is shut off, the thread loosening link 14 is moved in the direction of arrow C by a starting safety arm (not shown), thereby interlocking with the thread loosening lever 15. The tip of the upper arm is inserted between the thread tension discs 26/27 of the first thread tension 17, creating a gap between the discs and zeroing the thread tension.
At almost the same time, the shaft 16 and the lever 1 are interlocked, and the cam shape at the tip of the thread lifting arm 19 allows
The third thread tension 20 has a mechanism/operation similar to that of the second thread tension 5 in FIG. 3, so that the thread tension becomes zero. When the sewing machine rotates at a low speed, the starting safety arm (not shown) moves from the position at the time of shutoff in the direction opposite to the above-mentioned C direction, and the tip of the thread lifting arm 19 moves from the position at the time of shutoff to the midpoint of the amount of movement at the time of high speed rotation. Due to the cam shape being in the active state, the third thread tension 20 is in a state of zero tension. As mentioned above, the operation timing of each thread tension in the conventional example shown in FIGS. 3 and 4 is shown in Table 1, 1, 2,
It is as follows. 3 will be described later.

[Table] [Problems to be solved by the invention] As is well known, the needle thread pattern changes depending on the number of revolutions of the sewing machine.
The way the stitches are made, the needle thread tension, etc. are different, and if the difference between high and low speed rotation is particularly large, the sewing will not be stable unless the tension is changed accordingly.
However, in the conventional technology as shown in FIG.
Three thread tensions 17, 17, 17, 17, 17, 17, 17, 17, 17, 17 _, 20, 20, 20, 20, 30, 30, 30 threads of tension,
13 and 20 are provided, however, since each thread tension adjustment has an effect in relation to each other, correct adjustment is extremely complicated and requires skill. In addition, in the conventional technique as shown in FIG. 3, there are two thread tensions, numbered 10 and 5, so adjustment is relatively easy, but it is impossible to adjust to speed changes. In particular, it was difficult to maintain a stable sewing tension at _L2s during the second bar tacking at low speed. Furthermore, in both conventional examples, thread slack is generated in order to prevent the thread from falling out at the beginning of sewing, but due to changes in the amount of slack, and because the tension is zero for the first few stitches, Particularly in the case of synthetic yarns, there is a disadvantage that the amount of needle thread fed out from the hook is large and the needle thread is likely to break due to the hook. The present invention was developed in view of the problems of the conventional methods as described above, and it can cope well with the sewing characteristics of each process and the high/low sewing machine rotation speed when sewing sleep buttonholes. The purpose of this invention is to provide a thread tension control mechanism that is easy to adjust. [Means for Solving the Problem] Therefore, in the present invention, a first thread tension member is provided with one thread tension spring, and a second thread tension member is provided with one main thread tension spring and one sub thread tension spring. The above object is achieved by configuring each of the thread tension springs to be selectively releasable. [Function] With the above-described mechanism, each spring for each thread tension can be easily adjusted in accordance with the sewing characteristics and rotation speed of each process without affecting each other, and the quality of sewing can be improved. [Examples] The present invention will be described below based on Examples.
First, a perspective view of a main part of the thread tension control mechanism according to the present invention is shown, and FIG. 2 is an enlarged longitudinal sectional view of the second thread tension 29 thereof. (Structure) The structure of this embodiment is similar to that of the prior art example shown in FIG. 57
The release mechanism of the first thread tension 57 is generally similar to that shown in FIG. 3, but the second thread tension 29 is equipped with an adjustable (main) thread tension spring 46. In addition, an auxiliary thread tension spring 52 with minute pressure is added, and a release mechanism for both of the springs is provided. (Mechanism/Operation) This will be explained with reference to FIGS. 1 and 2 and the above-mentioned Table 1 C showing the operation timing according to the present invention. First, in FIG. 1, the thread loosening link 30 is moved in the direction of arrow D by a starting safety arm (not shown) in the following stroke order: when the upper shaft of the sewing machine rotates at high speed → when it rotates at low speed → when it stops cutting off. Then, when stopping and stopping → when rotating at low speed → when rotating at high speed, it is sequentially moved in the direction opposite to arrow D with respective strokes. During low-speed rotation and interruption, the thread loosening link 30 moves in the direction of arrow D, thereby loosening the first thread loosening arm 3.
1. In conjunction with the thread loosening lever shaft 32 and the thread loosening lever 3, the first thread loosening pin 34 is pushed upward, and the thread tension plate 36 of the first thread tension 57 is pushed upward. ,
Since a gap is generated between both thread tension discs 36 and 35, the tension of the upper thread (not shown) between them becomes zero. A second thread tension loosening arm 37 is fixed to the other end of the thread loosening lever shaft 32, and the second thread tension loosening link is pivotally supported by a pin 39 to the sewing machine mechanism via a link 58. 38, and the wedge-shaped tip 40 at the other end of the link 38 is inserted between both thread tension discs 41, 42 of the second thread tension 29, and is inserted between the discs only when the sewing machine is stopped. It is set to create a gap. Further, the second tension plate 29 is operated by a thread lifting notch (not shown) on a cloth feed cam (not shown) that moves the thread lifting bar 28 in the direction of arrow E during bar-tacking. By pushing the thread loosening pin 44 in FIG. Although it no longer acts on the discs 41 and 42, the auxiliary thread tension spring 52, which has a very small compressive force applied to its outer periphery, acts on the thread tension disc 41 via the thread tension disc holder 54,
Only a minute tension is generated by the auxiliary thread tension spring 52 on the upper thread (not shown) located between both thread tension discs 41 and 42. In addition, in Fig. 2, 50 is a thread tension rod stand;
51 is a thread take-up spring, 53 is an adjustment knob, and 55 is a thread tension rod. (Effects of Example) With the above configuration/operation, the above-mentioned Table 1 C
The thread tension timing shown in is obtained, and with two thread tensions, each parallel section P1, P of high-speed purl stitching is
2. The thread tension can be freely adjusted according to the sewing characteristics of the first bar-tacking section L1 for high-speed whip stitching and the second bar-tacking section _L2 for low-speed whip stitching, and it is also suitable for high-speed rotation when high tension is required. Since the needle thread tension can be adjusted using the second thread tension located close to the thread take-up lever, there is little influence on the other first thread tensions, and stable, high-quality sewing can be easily obtained. In addition, in the conventional method, the needle thread is slackened by the thread pulling wire 60 between the first thread tensioner (FIG. 3 10 or FIG. 4 17) that applies tension to the needle thread and the thread take-up thread. The amount of needle thread being fed out to the hook at the beginning was unstable, but in this embodiment, even if the same thread pulling device (not shown) and its position as in the past were used, the second thread pulling device located near the thread take-up By applying a minute tension to the slack upper thread with the auxiliary thread tension spring 52 of the thread tension 29, the amount of the upper thread fed into the hook is stabilized, and a great effect is obtained in preventing the occurrence of the upper thread breakage phenomenon. (Other Embodiments) In the embodiments described above, the second thread tension 29 is
Although it is operated by a notch on a cloth feed cam (not shown), it may be operated directly or indirectly using a signal such as a stitch count or the like, electrically using a solenoid or the like. [Effect of the invention] As explained above based on the examples,
According to the present invention, by using a simple mechanism, thread tension can be properly and easily adjusted in accordance with each sewing characteristic in the process of forming a buttonhole and high/low sewing machine rotation speed. It can also contribute to preventing the occurrence of thread breakage, and can improve sewing quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of the thread tension control mechanism according to the present invention, FIG. 2 is an enlarged longitudinal sectional view of the second thread tension, and FIGS. 3 and 4 correspond to FIG. 1, respectively. FIG. 5 is an exploded perspective view of the second thread tension shown in FIG. 3, and FIG. 6 is an explanatory diagram of a sleep buttonhole sewing pattern. 28...Thread floating rod, 29...Second thread tension, 3
0... Thread loosening link, 37... Second thread tension loosening arm, 46... (Main) thread tension spring, 52... Sub-thread tension spring, 53... Adjustment knob, 57... First thread tension .

Claims (1)

[Claims for Utility Model Registration] Low-speed sewing of the first parallel portion P1, high-speed sewing of the first parallel portion, high-speed sewing of the first bar-tacking portion L1, high-speed sewing of the second parallel portion P2, second bar-tacking portion In a sleep buttonhole sewing machine that sequentially sews high-speed stitching at L2 and low-speed stitching at the second bar tacking section, the first thread tension is equipped with one thread tension spring that acts on the needle thread between the thread take-up and the needle thread supply source. means 57, and a second thread tension spring 46, 52 each having one main thread tension spring and one sub thread tension spring 46, 52 acting on the upper thread between the thread take-up lever and the first thread tension means.
a thread tension means 29, a mechanism means for selectively releasing the springs of each of the thread tension means D, 33, E, 28;
40 is provided, and only the secondary spring of the second thread tension means is operated during low-speed sewing of the first parallel section and the second bar-tacking section, and high-speed sewing of the first parallel section and the second parallel section is provided. The springs of the first thread tension means and the second thread tension means act during sewing, and the sub springs of the first thread tension means and the second thread tension means operate during high-speed sewing of the first bar tacking section and the second bar tacking section. A sleeping hole sewing machine characterized by having a function of: