JPH11114267A - Pot for bobbin thread for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease fluctuation of drawing tension of a bobbin thread when used as a vertical taking by making the flange part of one side of a bobbin thicker as it approaches to the central side toward the flange part of another side. SOLUTION: Flange parts 3a and 3b are integrally constituted on both sides of a winding shaft 3c in a bobbin for a bobbin thread. The flange 3a on a bobbin thread taking-out side has a smaller diameter than that of the flange 3b on another side and is thicker as it approaches the central side toward the flange 3b side of another side to form a conical bed shape. On this flange part 3a, as the bobbin thread drawing-out point approaches to the flange part 3a, the bending angle of the bobbin thread path becomes smaller to act to prevent the bobbin thread tension from being enlarged. I.e., even when the bobbin thread drawing-out starting point approaches as close as possible to the flange part 3a side of the bobbin thread taking-out side, the bending angle θof the bobbin thread path is not smaller than the angle expressed by the angle XYZ and it is possible to prevent the bobbin thread tension from becoming to at least a value determined by this angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bobbin thread bobbin set together with a bobbin case in an inner hook which constitutes a hook of a lockstitch sewing machine, and more particularly to a longitudinal bobbin thread bobbin for pulling out the lower thread in the bobbin axial direction. It is.

[0002]

2. Description of the Related Art A new type of lock stitch sewing machine in which a lower thread is taken out from a bobbin in the bobbin axial direction and is drawn out along a bobbin flange has already been developed by the present applicant and the like (Japanese Patent Application No. Hei 10-26139). No. 9-243448). As shown in FIG. 4, the shuttle comprises an inner shuttle 1, an outer shuttle 2, and a bobbin case 4 which is set in the inner shuttle 1 and accommodates the lower thread bobbin 3, and a stud at the bottom center of the inner shuttle 1. Lower bobbin 3 mounted on 1a
Is that one bobbin flange 3a is slightly smaller than the inner diameter of the bobbin case 4, and the other bobbin flange 3b is slightly larger than the inner diameter of the bobbin case 4 and smaller than the inner diameter of the inner hook 1. . As a result, the bobbin flange 3
A space adjacent to a is secured, and the bobbin 3 is loose in the circumferential direction, so that the lower thread Y can be taken out from the bobbin 3 in the bobbin axial direction and pulled out along the bobbin flange 3a. In FIG. 4, reference numeral 5 denotes a locking piece for locking the bobbin case 4 to the inner hook 1, 6 denotes a removal lever for retracting the locking piece 5 to remove the set bobbin case 4 from the inner hook 1, 7 Is a thread tension adjusting spring for applying tension to the lower thread Y.

In this shuttle, the winding end of the lower thread Y is taken out from the bobbin 3 along the edge of the small-diameter bobbin flange 3a in the axial direction of the bobbin, and a hole 4 is formed along the outer surface of the small-diameter bobbin flange 3a.
The thread is pulled out of the bobbin case 4 from a and guided to a groove 5c formed on the surface of the hook piece 5 and a groove 4b formed on the surface of the bobbin case 4 to thread the thread tension adjusting spring 7.

[0004]

As shown in FIG. 5A, when the bobbin winding diameter is large, the bobbin thread Y in the bobbin bobbin 3 moves from the position A to the two points on the edge of the bobbin flange 3a. Then, as the bobbin thread diameter becomes smaller, the withdrawal start point shifts toward the center side with b and c. Therefore, the angles θ1, θ2, and θ1 formed by the lower thread path Init, Lohot, and Haget become smaller in order. A smaller angle means that the lower thread is sharply broken at the edge of the bobbin flange 3a, and a greater force is required to move (draw) the lower thread along the edge of the bobbin flange 3a. Means that it is necessary. That is, as the bobbin winding diameter decreases, the bobbin thread tension increases.

Further, as shown in FIG. 5 (2), even at the same bobbin winding diameter, the angle at which the bobbin thread breaks depends on the position in the bobbin axial direction from which the bobbin thread is pulled out. That is,
When the pull-out start point changes to a position (h) near the bobbin flange 3a, an intermediate position (r), and a position far from the bobbin flange (3a), the angles θ6, θ5, and θ4 formed by the lower thread tilt, the tilt, and the null increase in order. That is, the lower thread tension increases as the drawing start point approaches the bobbin flange 3a, and the lower thread tension decreases as the drawing start point moves further away. As described above, in the bobbin shown in FIGS. 5A and 5B, the lower thread tension changes due to the use of the lower thread.
Uneven seams cannot be formed. Further, FIG.
As shown in (3), even when the lower thread is pulled out from the same position, the breaking diameter of the lower thread varies depending on the diameter of the bobbin flange 3a. In other words, if the bobbin flange 3a has a diameter of 3a1, 3a2, 3a3, the lower thread paths ヲ, ヲ, and ヲ are formed at angles θ7, θ8, θ.
As can be seen from FIG.
The larger the diameter of a, the lower the bobbin thread
The force required to move along the edge of a (draw out the lower thread) increases. Therefore, the force applied to the edge of the bobbin flange 3a increases, and the state of the bobbin flange 3a greatly affects the yarn tension. Therefore, a uniform seam cannot be formed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bobbin case of a sewing machine in which a change in a lower thread pull-out tension is small when the lower thread is used in a longitudinal direction for pulling a lower thread in a winding axis direction.

[0007]

Means for Solving the Problems In the lower thread bobbin of the sewing machine, one flange 3a is made thicker toward the center toward the other flange 3b (FIG. 1 (1)).

In the lower thread bobbin of the sewing machine, the diameter of the winding shaft 3c is made smaller from one flange 3a toward the other flange 3b (FIG. 1 (2)).

In the lower thread bobbin of the sewing machine, one flange 3a is made thicker toward the center toward the other flange 3b,
In addition, the diameter of the winding shaft is made smaller as it goes from one flange to the other flange.

In the lower thread bobbin of the sewing machine, the diameter of one flange 3a is extremely small as compared with the maximum winding diameter (FIG. 1 (3)).

In the lower thread bobbin of the sewing machine, the diameter of one flange 3a is extremely small as compared with the maximum winding diameter, and the diameter of the winding shaft is reduced from one flange toward the other flange. And

In the lower thread bobbin of the sewing machine, the diameter of one flange 3a is extremely small as compared with the maximum winding diameter, and one flange is made thicker toward the center of the other flange. .

In the lower thread bobbin of the sewing machine, the diameter of one flange is set to zero (FIG. 4).

In the lower thread bobbin of the sewing machine, the diameter of one flange portion is set to zero, and the diameter of the winding shaft is reduced toward the other flange portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, four typical embodiments of a lower thread bobbin of a sewing machine according to the present invention will be described in order.

The bobbin bobbin shown in FIG.
The two flanges 3a, 3b are integrated at both ends of the lower thread, and the flange 3a on the lower thread take-out side has a smaller diameter than the other flange 3b. The flange 3a on the lower thread take-out side has a truncated cone shape that becomes thicker toward the center toward the other flange 3b.

The frusto-conical flange 3a of the lower thread bobbin is
As shown in FIG. 5 (2), as the lower thread pull-out start point is closer to the bobbin flange 3a, the bending angle of the lower thread path becomes smaller and the lower thread tension is prevented from increasing. That is, even if the starting point of pulling out the lower thread is closer to the side of the flange 3a on the lower thread take-out side, the bending angle θ of the lower thread path does not become lower than the ortho in FIG. Is prevented from exceeding the value of. Accordingly, the range of fluctuation of the lower thread tension due to the change of the lower thread winding diameter is naturally smaller than that of the conventional lower thread bobbin. What is important here is the frustoconical flange 3a, and therefore the outer diameters of the flange 3a and the flange 3b may be equal.

In the bobbin bobbin shown in FIG. 1B, two flanges 3a and 3b are similarly integrated at both ends of the winding shaft 3c, and the flange 3a on the lower thread take-out side is separated from the other flange 3b. It has a small diameter. The winding shaft 3c has a truncated cone shape with a smaller diameter as it goes from the lower thread take-out side flange 3a to the other flange 3b.

The frusto-conical winding shaft 3c of the lower bobbin is also
It functions to prevent the lower thread tension from increasing. That is, when the distance from the lower thread take-out start point to the lower thread take-out side flange 3a is equal, the yarn path A and the lower surface of the flange 3a indicated by a one-dot chain line are assumed to have the same diameter of the winding shaft. The angle β between the yarn path B of the lower thread bobbin indicated by the solid line and the lower surface of the flange 3a is larger than the angle α, and the lower thread tension is correspondingly smaller. Accordingly, the same applies to the point that the fluctuation range of the bobbin thread tension depending on from which position in the bobbin axis direction the bobbin thread is drawn out is naturally smaller than that of the conventional bobbin bobbin. Also important here is the winding shaft 3c in the shape of a truncated cone, so that the outer diameters of the flange 3a and the flange 3b may be equal. When the frustoconical flange 3a shown in FIG. 1A is formed on the bobbin on which the frustoconical winding shaft 3c is formed, even if the bobbin thread is pulled out from any position, the lower bobbin can be pulled down. The thread tension hardly fluctuates, and a uniform seam can always be formed.

In the bobbin bobbin shown in FIG. 1 (3), two flanges 3a and 3b are similarly integrated at both ends of the winding shaft 3c, and the flange 3a on the lower thread take-out side is separated from the other flange 3b. Although the diameter is small, the winding shaft 3c has a constant thickness as before. In this bobbin, the flange portion 3a is extremely smaller than the maximum winding diameter of the thread layer 8 wound around the bobbin. FIG. 2 shows a structure in which the diameter of the flange 3a is reduced to the limit. That is, the bobbin bobbin shown in FIG. 2 does not have a flange on the bobbin thread take-out side.

The lower thread bobbin shown in FIGS. 1 (3) and 2 has an extremely small or no flange 3a as compared with the conventional lower thread bobbin. Means relatively large. Therefore, when the bobbin thread winding diameter is larger than the flange portion 3a, little bobbin thread tension is applied. If the bobbin thread diameter is smaller than the flange section 3a, the diameter of the flange section 3a is small, so that the maximum thread tension is never larger than in the conventional bobbin bobbin, and the fluctuation width can be reduced. .

In the lower thread bobbin shown in FIG. 1 (3), in addition to the above structure, as shown in FIG. 1 (1), the flange 3a is formed in a truncated conical shape, or as shown in FIG. 1 (2). , Reel 3c
May be shaped like a truncated cone, in which case a greater effect can be obtained in which the above two principles overlap.
Similarly, in the lower thread bobbin shown in FIG.
As shown in FIG. 7, the winding shaft 3c may be formed in a truncated cone shape. By doing so, it is possible to prevent the lower thread from being pulled out from the winding shaft.

In order to wind the lower thread around the lower thread bobbin shown in FIG. 2, a winding device shown in FIG. 3 is used. This winding device includes a thread drop preventing guide plate 10 having a hole 10a having a diameter smaller than the outer diameter of the bobbin shaft 3c of the lower thread bobbin;
The rotating shaft 9 has an outer diameter substantially equal to the inner diameter of the winding shaft 3c, and is provided with a traverse device (not shown). When winding the bobbin thread,
The lower thread bobbin is inserted until the end of c hits the guide plate 10.

[0024]

Since the present invention is constructed as described above, it has the following effects.

That is, in the case of using the lower thread in the longitudinal direction for pulling out the lower thread in the winding axis direction, the magnitude of the lower thread pulling tension is smaller than that of the conventional lower thread bobbin, and the fluctuation width is also smaller. Therefore, a uniform seam can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of some lower thread bobbins of the present invention.

FIG. 2 is a front view of another bobbin of the present invention.

FIG. 3 is a front view of a winding device for winding a thread around a lower thread bobbin shown in FIG. 2;

FIG. 4 is a diagram of a conventional vertical take-up pot, (1) is a plan view,
(2) is a longitudinal sectional view.

FIG. 5 is a view showing a lower thread path at each stage, at each time, or at a different flange diameter in a conventional lower thread bobbin, (1) is a plan view, (2) is a front view, and (3) is a plan view. is there.

[Explanation of symbols]

 3a flange 3b flange 3c winding shaft

Claims (8)

[Claims] 1. A lower thread bobbin of a sewing machine in which one flange portion becomes thicker toward the center toward the other flange portion. 2. A lower thread bobbin for a sewing machine in which the diameter of the winding shaft decreases from one flange toward the other flange. 3. The lower thread bobbin of the sewing machine according to claim 1, wherein the diameter of the winding shaft becomes smaller as going from one flange to the other flange. 4. A lower thread bobbin for a sewing machine wherein the diameter of one flange portion is extremely smaller than the maximum winding diameter. 5. The lower thread bobbin of the sewing machine according to claim 4, wherein the diameter of the bobbin becomes smaller as it goes from one flange to the other flange. 6. The lower thread bobbin of the sewing machine according to claim 4, wherein one of the flanges becomes thicker toward the center toward the other flange. 7. A lower thread bobbin for a sewing machine in which one flange has a diameter of zero. 8. The lower thread bobbin of the sewing machine according to claim 7, wherein the diameter of the winding shaft decreases toward the other flange.