JPS6069B2 - Thread guide device for horizontal full-rotation hook in zigzag sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thread guide device for a zigzag sewing machine.

When sewing a blind stitch including a super warp as shown in Figure 5 on a zigzag sewing machine with a horizontal full-rotation hook, the tighter side of the upper thread wraps around the thread pulling side of the upper thread, causing the thread to pull up. When the side is pulled up with a thread take-up, the thread tightening side is also pulled upward all at once due to the frictional resistance between the threads, creating a large amount of slack in the thread on the thread side located above the fabric, and this slack is removed during the thread tightening process. If the problem is not completely resolved, it may cause poor thread tightness.

The present invention aims to prevent this. First, with reference to FIG. 6, the formation state of the left stitch b following the right stitch c when blind stitching the left base line as shown in FIG.

The throat plate is omitted in Fig. 6, and 1 in Fig. 6 shows that the upper thread 3 inserted into the needle 2, which has pierced the fabric 1 and descended, is captured by the tip 4 of the inner hook, and then the needle 2 is moved above the fabric 1. It shows the state where it has fallen out.
As the needle 2 further rises and the inner hook further rotates in the direction of the arrow as shown in FIG. 5 is attached to the bobbin case (not shown), and then the inner hook is turned over and the upper thread is pulled up by the action of the thread take-up, and the cloth begins to be fed in the direction of the arrow. If the balance continues to rise, Figure 6 N
As the loop a contracts, the bobbin thread 6 pulled out from the bobbin 5 is pulled up. Furthermore, as shown in FIG.
Loop a, which separated from the tip of the inner pot and became free, is the 7th loop.
As shown in the figure, it is located almost below seam b and is pulled upward along the rotation stopper of the bobbin case.
The contact surface between the thread pulling side e and the thread tightening side d is small, and when the thread is being pulled up, the thread tightening side d is unnecessarily connected to the thread pulling side e.
Even if it does rise, the amount will not be small, and in the thread tightening process, the loose thread can be reliably pulled up and good thread tightness can be maintained. FIG. 8 shows a case where a horizontal full-rotation hook 7 is used to sew a pattern similar to the sewing pattern shown in FIG. 5.

In this case, the hook that has captured the loop a rotates counterclockwise and goes around the bobbin case (not shown) to which the bobbin thread bobbin 5 is attached, and as shown in FIG. Loop a is lifted from the balance.

Then, stitches are formed as shown in FIG. 8 W and V. In the thread pulling process for stitch formation, the loop a is located on the right side of the bobbin 5 as shown in FIG. As the threads become entangled, the frictional force between the threads increases, and when the loop a is pulled up with the thread take-up, the thread I on the tight thread side also rises, causing a large amount of friction on the thread d side as shown by the chain line in Figure 8 W. The yarn becomes loose and cannot be fully eliminated in the subsequent thread tightening step, resulting in poor thread tightening.

Therefore, the problem of yarn sagging caused by such a phenomenon cannot be sufficiently solved simply by increasing the thread holding tension of the tension plate of the needle thread tension regulator. That is, in the thread pulling process using a thread take-up, it is necessary to prevent the thread A on the thread tightening side of the loop A from rising together when the thread pulling side e is pulled up.

As a means to do this, it is necessary to apply a brake to the thread A on the thread tight side of loop a so that the thread A on the thread tight side of loop a does not rise accidentally together with the thread pulling side when the thread is pulled up, or In order to prevent the thread from getting entangled with the thread pulling up side, it is necessary to regulate the position of the thread on the thread tightening side. The present invention is realized based on the above-mentioned viewpoint, and will be described below based on the implementation sequence.

11 is a sewing machine bed, 12 is a mounting frame fixed to the lower part thereof, a cylindrical rotation shaft 14 is rotatably mounted on a support shaft 13 fixed to this frame 12, and a horizontal full-rotation hook 7 is fixed to the upper end thereof. .

Reference numeral 16 denotes a lower shaft rotatably attached to the lower part of the sewing machine pet 1, and the lower shaft 16 and the rotary shaft 14 are rotated by a spiral gear.

A pivot shaft 17 parallel to the rotating shaft 14 is fixed to the mounting frame 12, and the middle portion of a rotation preventing member 18 is rotatably attached to this shaft 17. The forked part 20 of the actuating part 19 connected to one end of this member 18 engages with the boss 22 of the eccentric cam 21 fixed to the lower shaft 16. It is in contact with the outer periphery of the body by a spring. Both ends of the locking member 18 are bent upward, and locking pieces 24 and 25 are provided at the upper ends of each bent portion, respectively. Reference numeral 26 denotes a bobbin case rotatably attached to the attachment opening of the hook 7, and on the upper side of this case 26 there is a hooking piece 2 of the rotation stopper 18.
A pair of receiving portions 27 and 28 are provided for alternately holding 4 and 25.

A thread guide 29, which is the key point of the present invention, is fixed to the bobbin case 26. This thread guide 29 is made of a steel plate formed into a substantially trapezoidal shape as shown in FIGS.
As shown in FIG. 2, a gap is provided between the lower surface of the fixed throat plate 30 and the upper end of the thread guide 29 to allow the thread to pass through.
The planar position of the thread guide is such that it is located immediately in front of the needle hole 30a of the throat plate 30, and the left inclined surface 29 of the thread guide 29 is located at the left baseline position of the needle, as shown in FIG. In addition, 5 in the figure is a bobbin thread bobbin, and 8 is a tip provided on the horizontal full-rotation hook 7. The operation of the apparatus of the present invention as described above will be explained using the motion curves of FIG. 9 which correspond to FIG. 8.

In Fig. 9, the horizontal axis shows the rotation angle of the upper thread, and the vertical axis shows the thread supply amount by the upper and lower parts of the thread take-up, the upper and lower layers of the needle pole, the horizontal and vertical positions of the feed dog, and the thread feed amount of the hook. yarn supply curve,
B is the vertical curve of the needle, C is the horizontal curve of the feed dog, D is the vertical curve of the feed dog, E is the hook threading curve, and F is the upper surface of the needle slope. starts one rotation, the thread take-up continues to rise following the previous step, and the needle bar begins to descend.

That is, at this stage, the feed dog is feeding the cloth as shown by curves C and D in the final step of tightening the thread formed in the previous step. After rotating 60 degrees from the 0 point, the balance reaches its highest point, the needle descends further, and the cloth is being fed.

After rotating approximately 100 degrees, the cloth stops and rotates at 180 degrees.
When the needle rotates, it pierces the fabric and reaches its lowest point. During this time, the thread take-up continues to descend and supply the upper thread. When the needle that has reached the lowest point begins to rise and the upper thread inserted into the needle is squeezed by the cloth and a small loop is formed, the tip 8 of the full-rotation hook captures the loop a, as shown in Figure 8.1. do. When the upper shaft rotates further and the needle reaches 2400, the needle slips out onto the fabric, but since the thread take-up lever is still descending, the upper thread continues to be supplied, and this upper thread is captured by the tip 8 and placed in the bobbin case 26. The loop a going around the outside is expanded as shown in Figure 8n. At this time"
The thread A on the side that passes through the top surface of the bobbin 5 in loop a is the thread guide 2.
9 is bent at this position and goes around the upper surface of the bobbin 5.The thread that goes around the lower surface of the bobbin 5 is not affected by the thread guide 29 in any way, and is bent in this position. It rotates smoothly. When the loop a separates from the tip 8 of the hook and becomes free, the balance rises, the loop a comes out of the bobbin case, and the cloth begins to move forward a little vertically.

At this time, the thread A of the loop a on the upper surface of the bobbin 5 rises along the inclined surface 29a of the thread guide 29, passes through the gap between the upper surface of the thread guide 29 and the lower surface of the throat plate, and is pulled upward. is formed.

However, in the case of the present invention, as the upper thread 3 pulled by the tip 8 begins to form a loop a, the base of the loop a on the side A that passes through the upper surface of the bobbin 5, ``that is, the part near the cloth,'' is the thread as shown in Figure 4. This is the 29a side of the guide 29.

As shown in FIG. 1, this 29a side is located near the front of the needle 2 that is furthest to the left, so even if the loop a comes off from the right side of the bobbin case 26, it will still remain on the roof. Since the thread tightening side A of a is regulated by hitting the left inclined surface 29a of the thread guide 29, the angle at which the thread is wound in on the thread tightening side relative to the thread pulling side is smaller than that of the conventional horizontal full-rotation hook. Therefore, the frictional surface is reduced, and when the thread pulling side is pulled up in the L thread pulling process, the amount by which the thread A on the tight thread side is also pulled up by the frictional force is reduced, and a large slack does not occur on the thread tight side d. Further, since the thread A on the thread tightening side of the loop a is in contact with the left inclined surface 29a of the thread guide 29, a brake is applied to the thread A on the thread bidding side, thereby suppressing the thread A from rising together with the thread A when the thread is pulled up.

In the embodiment, the thread guide is provided in the bobbin case, but the same effect can be obtained even if the thread guide is provided in a downward direction in front of the needle hole in the throat plate.

As described above, the present invention reduces the angle at which the thread is wrapped around the thread pulling side by regulating the position of the thread A on the thread tightening side of the loop a.
When threading, a brake is applied to the thread A on the thread tightening side, and in the thread pulling process, it prevents the thread E on the thread pulling side and the thread A on the thread tightening side from rising together with the pulling up. The thread on the pulling side is not affected by this thread guiding, and a smooth thread pulling action can be performed to obtain good thread continuity.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the main parts of a sewing machine using the device of the present invention; Fig. 2 is a partially longitudinal front view of the same as above; Fig. 8 is a perspective view of the bobbin case of the same as above; Fig. 4 is a plan view of the sewing machine of the present invention. Fig. 5 is a plan view showing an example of the seam, Fig. 6 is a perspective view showing the action of the
Figure 8 is a perspective view of the sewing process of a conventional sewing machine,
FIG. 9 is a motion curve diagram. 1...Fabric, 2...Needle, 3...Needle thread, 5
...Bobbin thread bobbin, 6...Lower thread, 7...--Horizontal full rotation hook, 8...Sword tip, a...Loop, b, c...
Stitch, A...the tightening side of the thread, opening...the pulling side of the thread. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Claims of Claims] 1. In a zigzag sewing machine having a horizontal full-rotation hook, the needle descends and the needle thread inserted into the needle is caught by the tip of the full-rotation hook, and travels around the outside of the bobbin case while forming a loop. In order to prevent the thread on the thread tension side from getting entangled with the thread on the thread pull-up side of the loop, a thread guide that regulates the thread on the thread tension side is positioned immediately before the needle hole in the throat plate. and positioning the inclined surface of the thread guide on the left baseline position side of the needle,
A thread guide device for a horizontal full-rotation hook in a zigzag sewing machine attached to a bobbin case. 2 Claim 1 in which the shape of the thread guide is substantially trapezoidal
A thread guide device for a horizontal full-rotation hook in a zigzag sewing machine as described in Section 1.