Sewing Machine Needle, Method for Producing a Sewing Machine Needle, And Sewing Method

Abstract

A sewing machine needle includes a blade extending substantially in the needle's longitudinal direction, an eye, which passes through the needle substantially in its elevational direction, and a scarf, which extends along the needle behind the eye. Compared with the contour of the blade, the scarf contour is recessed in the needle's elevational direction. At least in part of the scarf s extension along the needle, the scarf contour in a sectional plane perpendicular to the needle's longitudinal direction is substantially an arc of a circle. The circular-arc-shaped area covers a first angular portion of the needle's circumference. In this part of the scarfs extension along the needle, the radius of the substantially circular-arc-shaped contour in this first angular portion of the needle's circumference is between 35% and 100% of the needle's maximum lateral reach. The needle's lateral direction is perpendicular to its longitudinal and elevational directions.

Claims

1. Sewing machine needle (1) comprising: a blade (5), which extends substantially in a longitudinal direction (L) of the needle (1), an eye (6), which passes through the needle (1) substantially in its elevational direction (H), the elevational direction (H) of the needle (1) being perpendicular to the longitudinal direction (L); a scarf (10), which precedes the eye (6) in the longitudinal direction (L) of the needle (1), the scarf's (10) contour (11) is recessed in the elevational direction (H) of the needle (1) in comparison with the contour of the blade (5), wherein a maximum cross-sectional area of the needle (1) in a portion (9) of the scarf's (10) longitudinal extension (L) along the needle (1) is between 60% and 80% of a smallest cross-sectional area, measured perpendicular to the longitudinal direction (L) of the needle (1), in an area over which a remainder of the blade (12) extends longitudinally and wherein, in the portion (9) of the scarf (10), the needle (1) has a maximum reach (h) in the elevational direction (H) that is between 55% and 75% of the needle's (1) maximum reach (b) in the lateral direction (B) in the portion (9) of the scarf (10), and wherein, at least in a section of the scarf's (10) extension in the longitudinal direction (L) of the needle (1), the contour (11) of the scarf (10) in a sectional plane perpendicular to the longitudinal direction (L) of the needle (1) is configured to be circular-arc-shaped, wherein this circular-arc-shaped area covers a first angular portion (w1) of the needle's circumference (3) wherein: the radius (r) of the circular-arc-shaped contour in the first angular portion (w1) of the needle's circumference (3) in the section of the scarf's (10) extension in the longitudinal direction (L) of the needle (1) is between 45% and 60% of the maximum reach (b) of the needle (1) in its lateral direction (B), the lateral direction (B) being perpendicular to the longitudinal (L) and elevational (H) directions of the needle (1).

2. Sewing machine needle (1) according to claim 1, wherein in the sectional plane through the portion (9) of the scarf (10), the circular-arc-shaped contour (11) of the needle (1) covers a first angular portion (w1) of at least 90.

3. Sewing machine needle (1) according to claim 1, wherein in the portion (9) of the scarf's (10) extension in the longitudinal direction (L) of the needle (1), the needle (1) attains the maximum reach (b) in the lateral direction (B) beneath a central axis (M) between 25% and 40% of its maximum reach in the elevational direction (H), as measured from a side facing away from the scarf (10).

4. Sewing machine needle (1) according to claim 1, wherein in the portion (9) of the scarf (10), the maximum reach of the needle (1) in the lateral direction (B) corresponds substantially to a minimum of the needle's (1) maximum reach (bs) in the lateral direction (B) in the remainder of the needle blade (12).

5. Sewing machine needle (1) according to claim 1, wherein the needle (1) has a longitudinal groove (8), which extends substantially in the longitudinal direction (L) of the needle (1) and which is located on the side of the needle (1) facing away from the scarf (10).

6. Sewing machine needle (1) according to claim 5, wherein over its entire extension in the longitudinal direction (L) and in the scarf's (10) area, the longitudinal groove (8) runs substantially parallel to and at a constant distance from the needle's central axis (M).

7. Sewing machine needle (1) according to claim 1, wherein in the section (9) of the scarf's longitudinal extension, the contour (11) of the needle (1), seen in a cross-sectional view obtained by cutting through the needle (1) at right angles to its longitudinal extension (L), has, in addition to the first angular portion (w1), at least a second angular portion (w2), which runs in a straight line, and that a third angular portion (w3) connects the first angular portion (w1) and the second angular portion (w2), said third angular portion (w3) forming a kink-free connection between the first angular portion (w1) and the second angular portion (w2).

8. Sewing machine needle (1) according to claim 1, wherein in the portion in which the scarf (10) extends in the longitudinal direction (L) of the needle (1), in a sectional plane perpendicular to this longitudinal direction (L), the sewing machine needle (1) is configured mirror-symmetric about a symmetry axis (S) defined by the elevational direction (H) and the needle's central axis (M).

9. Method of producing a sewing machine needle (1) comprising a blade (5), which extends substantially in a longitudinal direction (L) of the needle (1) and has an eye (6) that passes through the needle (1) substantially in its elevational direction (H), the method comprising: reducing the cross-sectional area of the blade (5) in a section thereof, and deforming the blade (5) without cutting action for providing at least one scarf (10), wherein in a first angular portion (w1), the scarf (10) is formed with a roundness radius (r) that corresponds to 45% to 60% of a maximum width (b) of the sewing machine needle (1) in a portion (9) of the scarf's (10) extension in the longitudinal direction (L) of the needle (1), a lateral direction (B) being at right angles both to the longitudinal (L) and the elevational (H) directions.

10. Method of producing a sewing machine needle (1) according to claim 9, further comprising reducing the cross-sectional area without removing any material.

11. Method of producing a sewing machine needle (1) according to claim 9, further comprising work-hardening residual material of the sewing machine needle (1) during reduction of the cross-sectional area.

12. Sewing method in which at least one sewing needle (1) and at least one looper are used, the sewing needle (1) comprising: a blade (5), which extends substantially in a longitudinal direction (L) of the needle (1), an eye (6), which passes through the needle (1) substantially in its elevational direction (H), the elevational direction (H) of the needle (1) being perpendicular to the longitudinal direction (L); a scarf (10), which precedes the eye (6) in the longitudinal direction (L) of the needle (1), wherein the scarf's (10) contour (11) is recessed in the elevation direction (H) of the needle (1) in comparison with the contour of the blade (5), and wherein, at least in a section of the scarf's (10) extension in the longitudinal direction (L) of the needle (1), the contour (11) of the scarf (10) in a sectional plane perpendicular to the longitudinal direction (L) of the needle (1) is configured to be circular-arc-shaped, this circular-arc-shaped area covering a first angular portion (w1) of the needle's circumference (3); and the method comprising: the at least one looper picking up a thread loop during routine operation as part of a hooking motion during which the at least one looper reaches past the extended needle (1), the looper colliding with the needle (1) in the first angular portion (w1) of the needle (1) in response to an operational deflection of the needle (1), wherein the needle (1), in the first angular portion (w1), has a contour with a roundness radius (r) that is between 45% and 60% of a maximum reach (b) of the needle (1) in its lateral direction (B), wherein the lateral direction (B) is perpendicular to the longitudinal (L) and elevational (H) directions of the needle (1).

Description

[0030] FIG. 1 shows a simplified oblique view of the scarf of a sewing machine needle according to the invention

[0031] FIG. 2 shows a simplified oblique view of the longitudinal groove of a sewing machine needle according to the invention

[0032] FIG. 3 shows a sectional view of the contour of the sewing machine needle according to the invention in the scarf

[0033] FIG. 4 shows a sectional view of the contour of the sewing machine needle according to the invention in the blade

[0034] FIG. 1 shows a simplified oblique view of the scarf 10 of a sewing machine needle 1 according to the invention. The sewing machine needle 1 extends in the longitudinal direction L from a shank 4 at one end through the blade 5 and the eye 6 to the point 7. The portion 9 of the scarf 10, said portion extending from the immediate vicinity of the eye 6 over part of the length of the blade 5, is also shown. The remaining portion 12 of the blade 5 is indicated too. The contour 11 of the needle in a sectional plane through the portion 9 of the scarf 10, perpendicular to the longitudinal direction L, is roughly recognizable. The longitudinal direction L, the lateral direction B and the elevational direction H have been added for purposes of orientation.

[0035] FIG. 2 shows a simplified oblique view of the longitudinal groove 8 of the sewing machine needle 1 according to the invention. Except for the scarf 10, the individual sections along the length of the sewing machine needle 1 are shown here as well. It is particularly evident that the longitudinal groove 8 and the edges thereof, which protect the sewing thread (not shown) during sewing, is straight and has no steps.

[0036] FIG. 3 shows a sectional view of the contour 11 of the sewing machine needle 1 according to the invention in the scarf of FIG. 1. The section can have been cut at any arbitrary point in the portion 9 of the scarf 10 except for the transition areas between the portion 9 of the scarf 10 and the eye 6 and between the portion 9 of the scarf 10 and the remaining area 12 of the blade 5. In this view, the scarf 10 is at the top and the longitudinal groove 8 at the bottom. The roundness radius r is shown as an arrow line. The angular portions w1, w2 and w3 are indicated with dashed lines. A coordinate system showing the lateral direction B and the elevational direction H has been added for clarification. The longitudinal direction L is perpendicular to the plane of the drawing. Within the contour and parallel to the lateral direction B, the maximum reach b of the sewing machine needle 1 in the portion 9 of the scarf 10 is identifiable. In this drawing, the central axis M runs perpendicular the plane of the drawing and is defined by the intersection of the two discontinuous lines, of which the one parallel to the elevational direction H is labelled with the reference numeral S. In the portion 9 of the scarf 10, the contour 11 of the sewing machine needle 1 is mirror symmetric about the symmetry axis S. The vertex of the angular portions w1, w2 and w3 is the intersection of the symmetry axis S with the line parallel to the lateral direction B, on which the needle has its maximum lateral reach b. The distance I between the longitudinal groove 8 and the central axis M is shown by an arrow. A transition 13 and a straight portion 14 are shown on the left side of the contour 11. The transition 13 connects the straight section 14 in kink-free manner with the substantially circular-arc-shaped contour of the first angular portion w1.

[0037] FIG. 4 shows a sectional view of the contour of the sewing machine needle 1 according to the invention in the blade 5. This contour, too, may be obtained anywhere along the blade 5 except for the transition areas, where it deviates. The coordinate system with the lateral direction B and the elevational direction H has again been added for orientation purposes. Here too, the contour is mirror symmetric about the axis S, which runs through the central axis M and parallel to the elevational direction H. The maximum lateral reach bs of the sewing machine needle 1 in the remaining area 12 of the blade 5 is shown. This corresponds to the maximum reach b, in the lateral direction B, of the sewing machine needle 1 in the portion 9 of the scarf 10 of FIG. 3. The maximum reach bs may deviate from the maximum reach b if, for example, the needle is of tapered design.

TABLE-US-00001 List of reference numerals 1 Sewing machine needle 3 Needle circumference 4 Shank 5 Blade 6 Eye 7 Point 8 Longitudinal groove 9 Portion of scarf 10 Scarf 11 Contour 12 Remaining area of blade 13 Transition 14 Straight portion b Maximum reach, in the lateral direction B, of the sewing machine needle 1 in the portion 9 of the scarf 10 bs Maximum reach, in the lateral direction B, of the sewing machine needle 1 in the remaining area 12 of the blade 5 h Maximum reach, in the elevation al direction H, of the sewing machine needle 1 in the portion 9 of the scarf 10 l Distance between the longitudinal groove 8 and the central axis M r Roundness radius w1 First angular portion w2 Second angular portion w3 Third angular portion B Lateral direction H Elevational direction L Longitudinal direction M Central axis S Symmetry axis