JPH11216289A - Sewing machine needle and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture the sewing machine needle of high quality provided with buckling rigidity sufficient as the sewing machine needle for hardly causing breakage accidents, to improve productivity as well and to manufacture it at a low cost by press-molding the needle trunk part of the sewing machine needle without forming burrs at the needle trunk part. SOLUTION: A thread groove 5 is turned to a curved bottom surface recessed groove 11 whose bottom surface is curved in a circular arcuate shape from a part near a needle hole toward a handle part close to the part corresponding to the tip part of a back groove provided on the opposite side of the thread groove and is provided with a flat bottom surface recessed groove 12 whose bottom surface is turned to a flat shape through the part for smoothly changing from the curved bottom surface 11 to the tapered part of the handle part. Thus, this needle of the high quality provided the sufficient buckling rigidity for hardly causing the breakage accidents is provided. Also, since a gap between a needle trunk and a sewing thread is secured large, stable sewing work is performed and a high-speed operation is made possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine needle and a method of manufacturing the same, and more particularly to a sewing machine needle formed by pressing metal wire and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a sewing needle, it is known that a metal wire is formed into a sewing needle by press working such as die press work or flow press work instead of cutting metal wire material. However, in these known press workings, a metal drawing material, that is, a metal blank material is partially punched, and a combination of grinding and polishing operations is performed. In each operation, it is necessary to use various different pressing dies. It was manufactured after such work. In addition, in this conventional press working, in forming with a die,
Burrs appear on the stem portion of the sewing machine needle, and it takes time and labor to cut off the needle. Therefore, it has been proposed to perform a flow press operation in which burrs do not appear on the needle stem portion. (US Pat. No. 4,044,814)

[0003]

However, in order to form a needle stem portion of a sewing machine needle from a metal wire drawing material by a flow press operation without forming burrs on the needle stem portion, an extra space is formed between a pair of dies. It is necessary that the metal blank material flowing and occupying the space is small compared to the volume of the space. On the other hand, if the amount of the metal blank material is too small, or if the thread groove is formed by coining work involving the formation of burrs, the strength and quality of the needle will be reduced and the product will become defective, resulting in increased scrap loss and the work. The procedure is complicated, the productivity cannot be increased, and the production cost is high. In addition, even if a hole is formed near the needle hole in the needle stem, if the depth is too small to secure a sufficient depth, if the sewing thread is guided in a slightly stretched state, a loop (thread loop) is formed. When the sewing needle is fixedly held on the sewing machine, it is necessary to adjust the timing of the sewing machine or adjust the feed dog. However, the adjustment is extremely troublesome and there is a problem that the handling workability is deteriorated.

SUMMARY OF THE INVENTION The present invention is intended to eliminate these conventional drawbacks, and has a sufficient buckling rigidity as a sewing needle by forming a needle stem of a sewing needle without forming burrs on the needle stem. It is an object of the present invention to provide a sewing machine needle that can be easily manufactured with high quality without causing breakage accidents, can be manufactured with high productivity, and can be manufactured at low cost. In the present invention,
It is an object of the present invention to provide a sewing needle which can secure a large gap between a needle stem and a sewing thread, can perform a stable sewing operation, and can operate at a high speed. Another object of the present invention is to provide a high quality sewing product that does not require adjustment of a sewing machine at the time of sewing work, is easy to handle sewing needles, and has a high quality. Further, another object of the present invention is to provide
A method of manufacturing a sewing needle that has sufficient strength to perform a stable sewing operation, and to easily and inexpensively manufacture a high-quality sewing needle that enables high-stable sewing operation and high-speed operation. Is to provide.

[0005]

The present invention comprises a handle at one end, a needle stem extending from the handle to the other end via a tapered portion, and a needle tip formed at the tip of the needle stem. A thread groove as a continuous concave front groove extending from the handle portion to a portion close to the needle tip; a continuous concave back groove and a short groove extending from the handle portion toward the needle tip on the opposite side to the thread groove; ,
A sewing machine needle comprising: a needle hole portion penetrating the thread groove and the short groove; and a hollow portion formed in a thin portion of the needle stem between a portion close to the needle hole portion and a back groove. The groove has a curved bottom concave groove whose bottom surface is curved in an arc shape from a portion close to the needle hole toward the handle portion to a position corresponding to a front end portion of the back groove on the opposite side to the thread groove. A flat bottom groove having a flat bottom surface through a portion that gradually changes from the bottom surface is provided over the tapered portion of the handle portion.

[0006]

According to an embodiment of the present invention, a handle portion is provided at one end, a needle stem extending from the handle portion to the other end via a tapered portion, and a needle tip formed at the tip of the needle stem. A thread groove as a continuous concave front groove extending from the handle portion to a portion near the needle tip, and a continuous concave back groove extending from the handle portion to a portion near the needle tip on the opposite side to the thread groove; A sewing machine needle comprising a short groove, a needle hole portion penetrating through the thread groove and the short groove, and a hollow portion formed in the needle trunk between a portion close to the needle hole portion and a back groove. The thread groove has a curved bottom concave groove whose bottom is curved in an arc shape from a portion close to the needle hole toward the handle portion to a position corresponding to the tip of the back groove on the opposite side to the thread groove. A flat bottom groove with a flat bottom surface through a part that gradually changes from the curved bottom surface It is provided over the tapered portion of the handle portion, and when forming a thin portion corresponding to the hole portion of the sewing machine needle of the finished product in advance and performing die press processing on the entire needle shaft, without forming burrs on the needle shaft. It is possible to form a hollow portion having a sufficient depth and to provide a high-quality sewing needle having a sufficient rigidity.

A sewing needle according to the present invention comprises a cylindrical handle having a large diameter, a needle stem extending from the handle,
A thread groove formed of a sharp needle tip formed at the tip of the needle stem and extending from the handle portion to a portion close to the needle tip as a continuous concave surface groove, and a needle hole formed along the thread groove A portion, and a gouge formed in the needle stem,
Further, the needle stem has a large-diameter first needle stem and a small-diameter second needle stem formed by two tapered portions formed at an interval on the opposite side of the thread groove, and is connected to the second needle stem. A narrowed portion having a cross-sectional shape smaller than the cross-sectional area of the second needle stem, a hollow portion on a side opposite to the thread groove of the narrowed portion, and a thread groove near the needle hole of the second needle stem. The inner and outer sides expanded at a predetermined angle to define are formed by die pressing the entire needle stem including the undercut,
The needle stem is extended in two stages, the first needle stem and the second needle stem, so that a constricted portion having a hole with a sufficient depth above the needle hole is formed, and the rigidity of the entire needle is increased. In addition, the gap between the needle stem and the sewing thread can be increased during sewing, so that the sewing operation can be performed stably and efficiently.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the example of the sewing machine needle shown in FIGS. 1 to 6. A handle portion 1 is provided at one end and a needle stem 3 extending from the handle portion 1 to the other end via a tapered portion 2. A thread groove 5 as a continuous concave surface groove extending from the handle portion 1 to a portion close to the needle tip, the thread groove 5 comprising a needle tip 4 formed at the tip of the needle stem; A continuous concave back groove 6 and a short groove 7 extending from the handle portion 1 to a portion near the needle tip 4, and a needle hole portion 8 penetrating through the thread groove 5 and the short groove 7.
When, in the above the needle 10 with a gouge portion 9 formed on the slender portion 3 ₁ of the needle stem 3, the thread grooves 5 are needle hole portion between the Uramizo 6 from sites near the needle hole portion 8 A curved bottom groove having a curved bottom surface 11 whose bottom surface is curved in an arc shape from a portion close to 8 toward the handle portion 1 to a position corresponding to a tip portion of the back groove 6 on the opposite side of the thread groove 5; And a flat bottom groove having a flat bottom surface 12 extending from the curved bottom surface 11 to the tapered portion 2 of the handle portion 1 via a portion 13 which smoothly changes to a flat bottom surface 12. By doing this, needle run-out and deflection during sewing can be minimized, and needle breakage and stitch skipping can be reduced.
In addition, the depth of the back groove 6 can be made as large as possible by press working, and the rigidity of the needle stem can be increased to greatly improve the durability.

In this case, as shown in FIG. 2, as the thread groove 5, both sides of the curved bottom groove of the curved bottom surface 11 are tapered at 35 to 45 degrees, preferably 38 to 42 degrees, and more preferably. An inclination angle θ _{1 of} 40 degrees and an inclination angle of 20 to 30 degrees, preferably 20 to 25 degrees, and more preferably 22 degrees in a tapered shape on both sides of the flat bottom groove of the flat bottom 12. θ ₂ is preferable. By doing so, the area of the curved bottom surface 11 can be increased, and the bottom surface of the concave groove can be prevented from being thinned, and backup can be performed in terms of strength.
The upper opening width is prevented from being unnecessarily widened, and it is easy to take out without sticking to the die, so that productivity can be greatly improved. Also, the presence of the flat bottom groove of the flat bottom surface 12 makes the back groove 6 deep, improves the metal flow during plastic working, prevents burrs, and improves the deflection balance of the needle stem 3. Further, the thread groove 5 gradually decreases the depth of the groove at a portion that changes from the curved bottom groove to the flat bottom groove toward the needle tip, for example, 0.02 to 0.08 mm.
The needle stem 3 is reinforced by changing the range.

The outer surface of the needle body 3 in which the thread groove 5 is formed is a flat or curved inclined surface, and the inclination angle θ of both sides of the curved bottom groove of the curved bottom surface 11. _Three
From 10 to 25 degrees, preferably from 18 to 25
Degree, more preferably 24 degrees, and both side surfaces of the flat bottom groove of the flat bottom surface 12 are tapered to 20 to 25 degrees.
Degrees, preferably an inclination angle θ ₄ of 24 degrees,
Wherein in the vicinity of the needle hole portion 8, the outer surface of the Harimikitai 3, 10 to 15 degrees inclination angle theta ₅ on both sides have a flat or curved inclined surface tapered, preferably 14 to 1
Setting the angle to 5 degrees is effective because the thickness of both side walls can be strengthened.

[0011] As shown in FIG. 3, as the gouge portion 9, the slender portion 3 ₁ of Harimikitai 3, the width dimension of Harimikitai 3 near the needle hole portion HS (L), the gouge portion 9 Needle trunk 3
Of the width dimension HS (M) is 0.04 to 0.10
Needle 4 and handle 1 as slender within the range of (± 0.03)
Formed between the short groove 7 near the needle hole and the back groove 6 on the handle portion side, which are shifted to both end sides of the shaft, and both ends between the short groove 7 and the back groove 6. In addition, the raised portions 14 and 15 are provided in the needle stem 3 as deep undercuts to ensure a secure thread catch by a looper and facilitate the assist in forming a loop of a sewing thread.

FIG. 1 shows the shape of a sewing needle 10 after a two-step drawing process suitable for manufacturing a sewing needle according to the method of the present invention. Plastic processing such as construction, grinding processing is applied,
A small cylindrical portion 3 having a small diameter near the tip 4
₁ and tapered portions 30 and 31 respectively connecting both ends to the needle stem portion are formed. That is, in a method of pressing a metal needle material pre-processed before boring, a handle portion 1 at one end, a needle stem portion 3 extending from the handle portion 1 to the other end via a tapered portion 2, and a tip of the needle stem portion Needle tip 4 formed on
And a thread groove 5 as a continuous concave surface groove extending from the handle portion 1 to a portion near the needle tip 4 in the needle stem 3, and the needle from the handle portion on the opposite side to the thread groove 5. A continuous concave back groove 6 and a short groove 7 extending forward, a needle hole portion 8 penetrating through the thread groove 5 and the short groove 7, and a portion close to the needle hole portion 8 and between the back groove 6 And the undercut portion 9 formed on the needle stem 3 described above.

In this case, the needle material has a handle portion 1 having a large diameter and a cylindrical diameter, a first needle stem having a small diameter at one end of the handle portion 1, and a further smaller diameter at one end of the first needle stem. a needle stem 3 formed by concatenating a second needle stem, to form a slender portion 3 ₁ which corresponds to gouge portion 9 of the needle 10 to the second needle stem, the die press working the entire needle stem,
A thread groove 5 as a continuous concave surface groove, a side surface portion formed by expanding a continuous concave short groove 7 and a back groove 6 on a side opposite to the yarn groove 5 at a predetermined angle, and a bottom surface portion continuous with the side surface portion The thread groove 5 has a curved bottom surface 11 whose bottom surface is formed in an arc shape from the portion close to the needle hole portion 8 to the portion corresponding to the undercut portion 9 on the opposite side toward the handle portion. A curved bottom groove, and a portion 13, which gradually changes from the curved bottom groove,
For example, it is formed into a flat bottom groove having a flat bottom surface 12 having a flat shape over a tapered portion of the handle portion through an inconspicuous range (range of 1.0 to 1.5 mm).

[0014] The slender portion 3 _1, gouge portion 9 by it is desirable to shape the cross-sectional area in a die press working More preferably 65% to 60% to 70% of the cross-sectional area of the second needle stem. If the ratio of this cross-sectional area is less than 60%, the sewing machine needle after final finishing tends to have a too small cross-sectional area at the undercut portion 9 and thus have insufficient strength, and if it exceeds 70%, it tends to break. In this case, the necessary depth of the undercut 9 cannot be ensured, so that it should be considered. As shown in FIGS. 4 and 5, this die pressing uses upper and lower dies 20 and 21 facing each other. The V-shaped convex portion 22 of the upper die 20 and the corresponding concave portion 23 of the lower die 21 are used. And the inclination angle θ of the outer side surface of the second needle stem.
₃ 20-30 degrees, preferably in the range of 24 degrees, the inclination angle theta ₁ 35 to 45 degree inner surface of the groove is shaped preferably in the range of 40 degrees.

[0015] Then, the slender portions 3 _1, connects connecting the tapered portions 30 and 31 which is inclined with respect to the needle shaft at both ends to the needle hole portions 8 are formed respectively and the second needle stem,
It is preferable that the inclination angle of the tapered portion 30 close to the needle hole portion 8 is formed larger than that of the other tapered portion 31.
This slender portion 3 ₁ and both tapered portion 30 and 31, are deployed in a position corresponding to the depression 9 formed in the needle stem 3 of the needle 10 after final finishing. In addition, the slim as the part 3 _1, and its minimum penetration width HS (M), the size difference between the needle bore maximum needle width HS (L) 0.04 to 0.10,
Preferably, it is formed to have a depth of 0.05 to 0.07, and the holding angle of the lower die 21 of the needle stem 3 is changed from 24 to 25 degrees to 14 to 15 degrees, so that the die-pressing is deep. This is effective for forming the part 9.

[0016] As shown in FIGS. 4 to 6, when the die press processed into sewing needle 10 forming a slender portion 3 ₁ using a needle material, needle hole portion 8 having a thread groove 5 and the needle hole for the thin portion 32 And are formed. In this case, a continuous concave thread groove 5 extending in the length direction from the handle portion 1 to the vicinity of the tip of the needle stem 3 is formed in the needle material, and at the same time, the needle is formed along the thread groove 5 of the second needle stem. A needle hole portion 8 having a hole thin portion 32;
Has a or substantially U-shaped or V-shaped as a whole its cross-sectional shape, including a slender portions 3 ₁ opposite the gouge portion 9 is formed a thread groove 5 of the second needle stem portion, thread groove The inner part and the outer part defining 5 are each expanded at a predetermined angle.

[0017] The needle stem portion of the U-shaped cross section, the dimensions have become smaller towards the slender portion 3 ₁ a second needle stem portion, deformed slender portion 3 ₁ of the needle 10 The upper part of the needle hole portion 8 in the finished product is a throttle portion, and in particular, the side opposite to the thread groove 5 is retracted toward the center of the needle via two tapered portions 30 and 31 inclined at a predetermined angle with respect to the needle axis. A recess 9 is formed. In the needle hole portion 8, a short groove 7 extending from the vicinity of the undercut 9 to almost the needle tip 4 on the opposite side to the thread groove 5 except for the thin portion 32 for needle hole drilling,
A back groove 6 extending from the vicinity of the undercut portion 9 to almost the handle portion 1 is formed.

In the die pressing, a flat portion 33 is formed on the free end side of the second needle stem portion beyond the needle tip 4 to protrude in the lateral direction. By providing the flat portion 33, the flow of the metal of the needle material at the time of die pressing is improved, and the positional relationship between the needle material and the die in the length direction is predetermined. The flat portion 33 is also effective for positioning a die and a punch guide that enable accurate needle hole punching in a subsequent needle hole forming step. In this die pressing, an upper die 20 having a V-shaped convex portion 22 is used.
The needle stem 3 having the first needle stem portion and the second needle stem portion is pressed and deformed by the two dies using the lower die 21 having the concave portion 23 corresponding thereto. The metal of the needle stem is caused to flow into the gap, and the thread groove 5, the back groove 6, and the short groove 7 are formed without forming burrs on the needle stem.
And the thin portion 32 for the needle hole portion 8 are simultaneously formed.

In this case, it is desirable that the inner portion and the outer portion defining the thread groove 5 are respectively widened at a predetermined inclination angle, for example, at an angle of 10 to 28 degrees from the viewpoint of sewing and die pressing. That is, the angles θ ₁ and θ ₂ of the outer surface of the V-shaped convex portion 22 of the upper die 20 are less than 30 degrees, preferably 28 degrees in the needle stem portion 3, and the corresponding inner surface of the concave portion 23 of the lower die 21. angle theta _3, theta ₄ is desirably in the range of angle of 10 to 28 degrees. This is because if the angles θ ₁ and θ ₂ of the inner surface of the concave portion 23 are less than 20 degrees, the excess thickness flowing during press working becomes difficult to rise upward, the height of the needle stem decreases, and the excess thickness decreases. If it goes out toward the side, the durability of the lower die 21 will be impaired, and if it exceeds 28 degrees, the width of the needle stem will be too large. It is made large to prevent the entrance width of the yarn groove 5 from being unnecessarily expanded. In the vicinity of the needle hole 8, the angle θ ₅ of the outer surface of the V-shaped convex portion 22 of the upper die 20 is 25 degrees, and the corresponding angle θ ₄ of the inner surface of the concave portion 23 of the lower die 21 is 1 °.
The angle is in the range of 0 to 18 degrees, preferably 14 degrees.

That is, the angle θ of the inner surface of the concave portion 23
₄ is less than 10 degrees, the sewing needle does not come off from the shape at the time of press working, and if it exceeds 18 degrees, in order to make the needle stem width as specified, the bottom of the concave portion 23 of the lower die 21 should have a rounded angle. The radius is too small and the bank of the short groove 7 is too thin to be formed. Thus, the lower die 21
Angle theta ₂ of the inner surface of the needle hole portion of the recess 23, as the angle of 14 degrees, are taken into account as easily retrievable without sticks the needle 10 within the die during pressing.
Also, the angle θ of the outer surface of the V-shaped projection 22 of the upper die 20
_{No. 1} is determined in consideration of securing a sufficient size for easily forming a thread during sewing and increasing a sewing speed, and not increasing a needle stem width more than necessary.

The formation of the gouge portion 9, in order not punched extra bulge laterally constricted portion of the slender portion 3 ₁ at the time of press working, we are utilizing slender portion 3 ₁ a preformed. That is, the cross-sectional area of the narrowed portion where the undercut portion 9 of the sewing machine needle is formed is 65% of the cross-sectional area of the second needle stem.
It has set the outer diameter of slender portion 3 ₁ of the needle material. Further, the slender part 3 _first tapered portion 30 provided at both ends of and 3
Since the needle material extends in the needle axis direction at the time of pressing, it is better to set the shape 1 at an inclination angle by setting the length of the inclined portion in the axial direction.

The inclination angle of the tapered portions 30 and 31 is such that the tapered portion 30 near the needle hole is larger than the tapered portion 31 at a position away from the needle hole.
When the distance between the upper end of the needle hole and the undercut 9 is made as short as possible in a state where the needle hole 0 is attached to the sewing machine, the flow of the metal near the needle hole toward the thread groove 5 during press working is achieved, This is because a desired shape can be obtained for the thin portion 32 of FIG.

The tapered portions 30 and 31 which are positioned at both ends of the slender portion 3 ₁ of the sewing needle 10 is finished products,
It is considered that the dimensional relationship of the portions corresponding to these portions located at both ends of the thin portion of the needle material before die pressing is set at an appropriate ratio depending on the size of the finished sewing machine needle.

The needle material which has been subjected to the die pressing process cuts the thin portion 32 for the needle hole along the thread groove 5 to form the needle hole portion 8. At the time of forming the needle hole, the flat portion 33 at the tip of the needle tip is fitted into a receiving portion formed on the punch die,
The needle material is aligned and fixed to the die, and accurate drilling work is performed. Through this process, the tip of the needle stem is sharpened to complete the sewing needle 10 as the needle tip 4.

The sewing needle 10 completed as described above
As shown in FIG. 1 to FIG. 3, the second
A narrowed portion having a width smaller than that of the needle hole portion 8 is formed in the needle shaft portion, and a hollow portion which is retracted toward the center of the needle by two tapered portions 30 and 31 is provided on the opposite side of the narrowed portion from the thread groove 5. 9 are formed. Therefore, it is deflected inward by the undercut 9 above the needle hole 8, so that a large gap between the sewing thread and the needle stem can be ensured. In a state where the sewing machine needle 10 is mounted on the sewing machine, the upper end and the lower end of the needle hole portion 8 are each formed of a rounded curved edge.

The width HS of the needle hole portion 8 at the center of the needle hole
(L) and the width HS (M) of the central portion of the narrowed portion 38 are preferably defined as follows (unit: mm). For example, in the 7th JIS standard, HS (L) = 0.57,
HS (M) = 0.52 HS (L) = 0.62 in JIS standard 8th,
HS (M) = 0.57 In the ninth JIS standard, HS (L) = 0.69,
HS (M) = 0.62 In the 10th JIS standard, HS (L) = 0.74,
HS (M) = 0.67 In the eleventh of the JIS standard, HS (L) = 0.79,
HS (M) = 0.72 According to JIS standard No.14, HS (L) = 0.89,
HS (M) = 0.82 etc., and each tolerance of these dimensions is ± 0.02-0.
03.

Further, Table 1 shows the bending stiffness values of the sewing needle of the present invention of each number of the JIS standard and the conventional regular needle measured and compared.

[0028]

[Table 1]

In comparison with the product of the present invention and the conventional needle, the rigidity, the stapling prevention rate at the time of step sewing, the stitching prevention rate at the time of ordinary sewing, the penetration resistance, and the needle temperature are as follows. Significant product differences were noted.

Such a sewing machine needle according to the present invention has a shape in which the needle stem is drawn in two steps and the width of the needle stem in the cross-sectional shape is suppressed from increasing, thereby increasing the thickness in the vertical direction. The rigidity of the entire needle is sufficiently high. Therefore, the occurrence of breakage accidents during the sewing operation can be almost eliminated. Also, even with die press processing, the presence of the back groove makes plastic deformation easy and can deepen the thread groove,
Since a sufficiently deep undercut portion is also formed, the gap between the needle stem and the sewing thread is increased to stably perform the sewing operation, thereby enabling high-speed operation. Further, the surface of the needle is smoothly finished by press working, and the slender portion is formed, so that the penetration resistance can be improved and the needle heat can be reduced.

[0031]

The present invention comprises a handle at one end, a needle stem extending from the handle to the other end via a tapered portion, and a needle tip formed at the tip of the needle stem. A thread groove as a continuous concave front groove extending to a portion near the needle tip; a continuous concave back groove and a short groove extending from the handle portion toward the needle tip on the opposite side to the thread groove; A sewing machine needle comprising a needle hole portion penetrating through the needle groove and a short groove, and a hollow formed in a narrow portion of the needle trunk portion between a portion near the needle hole portion and a back groove. Is a curved bottom concave groove curved in an arc shape from a portion close to the needle hole toward the handle portion to a position corresponding to a tip portion of the back groove on the opposite side to the thread groove, and A flat bottom groove having a flat bottom surface through a portion that gradually changes from By having subjected par portion,
Forming the needle stem of the sewing needle without forming burrs on the needle stem, it has sufficient buckling rigidity as a sewing needle, significantly reduces needle runout and deflection during sewing, and causes breakage of the needle and skipping Thus, a high-quality sewing needle with almost no breakage can be easily manufactured, productivity can be increased, and it can be manufactured at low cost. With the sewing machine needle of the present invention, the groove can be deepened even in plastic working by press, a large gap can be secured between the needle stem and the sewing thread, the looper can reliably catch the thread, and the load on the thread can be reduced. It is possible to stably tighten the thread by reducing the number of threads, perform a good sewing operation, and also reduce the penetration resistance to enable high-speed operation, thereby greatly improving workability. Further, the present invention does not require adjustment of the sewing machine at the time of the sewing operation, and the handling operability of the sewing machine needle is simple, so that a high quality sewing product can be obtained. Furthermore, the present invention suppresses the width of the cross section of the needle stem from becoming large, and has a shape in which the needle has a thickness in the vertical direction. Work can be performed, and a high-quality sewing needle that enables highly stable sewing work and high-speed operation can be manufactured simply and at low cost. Therefore, the occurrence of breakage accidents during the sewing operation can be almost eliminated. Also, even with die press processing, the presence of the back groove makes plastic deformation easy and can deepen the thread groove,
Since a sufficiently deep undercut portion is also formed, the gap between the needle stem and the sewing thread is increased to stably perform the sewing operation, thereby enabling high-speed operation. Further, the surface of the needle is smoothly finished by press working, and the slender portion is formed, so that the penetration resistance can be improved and the needle heat can be reduced.

[Brief description of the drawings]

FIG. 1 shows a sewing needle manufactured by a method of the present invention, wherein (a) is an enlarged front view and (b) is a longitudinal sectional view thereof.

FIGS. 2A and 2B are enlarged cross-sectional views of each display portion of FIG. 1, wherein FIG. 2A is a cross-sectional view taken along line AA, FIG. 2B is a cross-sectional view taken along line BB, and FIG. Cross-sectional view taken along line, (d)
FIG. 3 is a cross-sectional view taken along line DD.

FIG. 3 is an enlarged rear view of a part of a distal end portion of the sewing needle of FIG. 1;

FIG. 4 is a longitudinal sectional view showing a sewing needle manufactured by the method of the present invention.

5A and 5B are enlarged cross-sectional views of each display portion of FIG. 4, wherein FIG. 5A is a cross-sectional view taken along line EE, FIG. 5B is a cross-sectional view taken along line FF, and FIG. FIG.

FIG. 6 shows the needle material of FIG. 4, wherein (a) is an enlarged longitudinal sectional view,
(B) is a cross-sectional view taken along line HH, and (c) is a cross-sectional view taken along line II.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Handle part 2 Taper part 3 Needle stem part 3 ₁ Slender part 4 Needle tip 5 Thread groove 6 Back groove 7 Short groove 8 Needle hole part 9 Hole part 10 Sewing needle 11 Curved bottom surface 12 Flat bottom surface 13 Deformation part 14, 15 Rising part 20 Upper die 21 Lower die 22 Convex part 23 Concave part 30 Tapered part 31 Tapered part 32 Thin part for needle hole 33 Flat part

Claims (10)

[Claims] 1. A handle portion at one end, a needle stem extending from the handle portion to the other end via a tapered portion, and a needle tip formed at the tip of the needle stem. A thread groove as a continuous concave front groove extending to a near portion, a continuous concave back groove and a short groove extending from the handle portion toward the needle tip on the opposite side to the thread groove, and the thread groove and the short groove. A sewing machine needle having a needle hole portion that penetrates into the needle hole portion, and a hollow portion formed in a narrow portion of the needle stem portion from a portion near the needle hole portion to a back groove. From the curved bottom surface to the handle portion, the bottom surface of which is formed into a curved bottom concave groove curved in an arc shape up to a position corresponding to the front end portion of the back groove on the opposite side to the thread groove, and the shape gradually changes from the curved bottom surface. A flat bottom groove with a flat bottom surface through the tapered portion of the handle Sewing needle, characterized in that it comprises Te. Wherein said yarn groove, the sides of the curved bottom groove and the inclination angle theta ₁ which was 35 to 45 degrees tapered, and 20-30 degrees both sides of the flat bottom groove in a tapered shape Sewing needles according to claim 1, characterized in that an inclined angle theta ₂ which is. 3. The outer surface of the needle body on which the thread groove is formed,
4. The sewing machine needle according to claim 1, wherein the machine needle has a flat or curved inclined surface, and the inclination angle of both side surfaces is tapered to 10 to 25 degrees. 4. The groove according to claim 1, wherein the depth of the groove that changes from the curved bottom groove to the flat bottom groove is gradually reduced toward the needle tip. 3
Or the sewing needle according to 4. 5. The underbore is formed between a short groove and a back groove near a needle hole at both ends of a needle tip side and a handle part side, and is provided between the short groove and the back groove. The needle stem is provided with raised portions at both ends of the needle stem.
The described sewing needle. 6. A handle portion at one end, a needle stem extending from the handle portion to the other end via a tapered portion, and a needle tip formed at the tip of the needle stem portion. A thread groove as a continuous concave front groove extending to a near portion, a continuous concave back groove and a short groove extending from the handle portion toward the needle tip on the opposite side to the thread groove, and the thread groove and the short groove. A method in which a sewing machine needle having a needle hole portion penetrating through the hole and a hollow formed in a narrow portion of the needle stem portion from a portion close to the needle hole portion to a back groove is manufactured by die pressing a needle material. In the above, the needle material has a cylindrical handle portion having a large diameter, a first needle stem having a small diameter at one end of the handle portion, and a second needle stem having a smaller diameter connected to one end of the first needle stem. And a slender part corresponding to the hole of the sewing needle on the second needle stem. A thread groove as a continuous concave surface groove is formed by die press processing on the entire needle stem portion, and a side groove portion in which a continuous concave short groove and a back groove are expanded at a predetermined angle on the opposite side to the yarn groove; The curved bottom surface is defined by a bottom surface that is continuous with the side surface, and the thread groove extends from the part close to the needle hole to the part corresponding to the undercut on the opposite side, toward the handle, and the bottom surface is made into an arcuate shape. In addition to the curved bottom groove having a flat bottom surface, the concave bottom surface was formed into a flat bottom groove having a flat bottom surface by extending the tapered portion of the handle portion through a portion that gradually changes from the curved bottom groove. A method for producing a sewing needle. 7. The die-forming part according to claim 6, wherein the narrow part is formed by a die press process so that a cross-sectional area of the narrow part is formed to be 60 to 70% of a cross-sectional area of the second needle stem. Manufacturing method of sewing needle. 8. The die press using upper and lower dies opposed to each other, wherein a V-shaped convex portion of an upper die and a corresponding concave portion of a lower die form an outer surface of the second needle stem. The method for manufacturing a sewing machine needle according to claim 6, wherein the inclination angle is set in a range of 20 to 30 degrees, and the inclination angle of an inner surface portion of the concave groove is formed in a range of 10 to 18 degrees. 9. The thin portion is formed at each end with tapered portions inclined with respect to the needle axis, connected to the needle hole and the second needle stem, and formed into a tapered portion close to the needle hole. 7. The method for producing a sewing needle according to claim 4, wherein the inclination angle is formed larger than that of the other tapered portion. 10. The thin portion has a minimum needle width HS.
(M) and the dimensional difference 0.0 between the needle hole portion maximum needle width HS (L)
6. A die press process, wherein the die is formed at 5 to 0.10 and the holding angle of the lower die of the needle stem is changed from 24 to 25 degrees to 14 to 15 degrees. , 6 or 7.