Abstract
A sewing machine needle (1) is described, which reduces the friction between the blade (2) of the sewing machine needle (1) and the fabric and which can be manufactured economically in large numbers. The sewing machine needle (1) includes a needle eye (3) and at least one recess (5), wherein the distance between an upper edge (6) of the recess (5) and the lateral position of the axis (12) of the needle eye (3) differs from the distance between a lower edge (7) of the recess (5) and the lateral position of the axis (12) of the needle eye (3).
Claims
1. A sewing machine needle (1), comprising: a blade (2) which extends in a longitudinal direction (L), a needle eye (3) which extends completely through the sewing machine needle (1) in an elevational direction (H), the elevational direction (H) being orthogonal to the longitudinal direction (L), a scarf portion (24) of the blade (2) extending along the longitudinal direction (L), the scarf portion (24) comprising a scarf (16); at least one recess (5) formed in the blade configured to reduce friction between the blade (2) and a fabric, wherein the at least one recess (5) extends outside of the scarf portion (2) in the longitudinal direction (L) and which reduces a reach of the blade (2) in a lateral direction (B), the lateral direction (B) being orthogonal to the elevational (H) and the longitudinal (L) directions, wherein the at least one recess (5) has an upper edge (6) and a lower edge (7), at which the at least one recess (5) ends in the elevational direction (H), wherein the at least one recess (5) has, at least at one position along its length in the longitudinal direction (L), a height (11) which corresponds to at least 30% of a height (10) of the blade (2) at the at least one position, and wherein an upper edge distance (O), which corresponds to a distance in the lateral direction (B) between the upper edge (6) of the at least one recess (5) and a position of an axis (12) of the needle eye (3) in the lateral direction (B), differs from a lower edge distance (U), which corresponds to a distance in the lateral direction (B) between the lower edge (7) of the at least one recess (5) and the position of the axis (12) of the needle eye (3) in the lateral direction (B).
2. The sewing machine needle (1) according to claim 1, wherein the at least one recess (5) has a uniformly shaped section (37), which makes up at least 10% of an entire reach of the at least one recess (5) in the longitudinal direction (L), and the at least one recess (5) has at every position along the uniformly shaped section (37), a height (11) which corresponds to at least 30% of the height (10) of the blade (2).
3. The sewing machine needle (1) according to claim 1, wherein the upper edge distance (O) is smaller than the lower edge distance (U).
4. The sewing machine needle (1) according to claim 1, wherein the at least one recess (5) and the scarf (16) at least partially overlap in the longitudinal direction (L).
5. The sewing machine needle (1) according to claim 1, wherein at least at one position along the length of the at least one recess (5) in the longitudinal direction (L), a distance in the elevational direction (H) between the upper edge (6) and a highest point of the blade (2) in the elevational direction (H) is a maximum of 35% of the blade height (10).
6. The sewing machine needle (1) according to claim 1, wherein a distance in the lateral direction (B) between a surface (13) of the sewing machine needle (1) and the axis (12) of the needle eye (3) is described by a lateral distance function (s (h)) wherein the lateral distance function (s (h)) is dependent on a height coordinate (h) and decreases monotonically, with increasing height over at least 90% of an elevational reach of the recess (5).
7. The sewing machine needle (1) according to claim 1, wherein the at least one recess (5) is spaced in the lateral direction (B) at every point therealong from a position of the axis (12) of the needle eye (3).
8. The sewing machine needle (1) according to claim 1, wherein a lead-in tangent (14) to the at least one recess (5) at the upper edge (6) encloses a lead-in angle (15) of 5 to 70 with the elevational direction (H).
9. The sewing machine needle (1) according to claim 1, wherein at least one thread groove (4) extends in the longitudinal direction (L) and follows on from the needle eye (3) in a negative longitudinal direction (L) and constitutes a depression in the elevational direction (H).
10. The sewing machine needle (1) according to claim 1, wherein at least at one point along the length of the at least one recess (5) in the longitudinal direction (L), in an area between the lower edge (7) and the upper edge (6), in a plane defined by the elevational (H) and lateral (B) directions, a surface (13) of the sewing machine needle (1) is shaped as a circular arc with a constant radius, and a center of the circular arc lies outside a cross-sectional area of the sewing machine needle (1) in the plane defined by the elevational (H) and lateral (B) directions.
11. The sewing machine needle (1) according to claim 6, wherein at least at one point along the length of the at least one recess (5) in the longitudinal direction (L), the recess height (11), which corresponds to the distance between the upper edge (6) and the lower edge (7) in the elevational direction (H), is 60% to 170% of a maximum of the lateral distance function (s (h)).
12. The sewing machine needle (1) according to claim 6, wherein at least at one point along the length of the at least one recess (5) in the longitudinal direction (L), the upper edge distance (O) is 10% to 60% of a maximum of the lateral distance function (s(h)).
13. The sewing machine needle (1) according to claim 6, wherein at least at one point along the length of the at least one recess (5) in the longitudinal direction (L), the lower edge distance (U) is 50% to 100% of a maximum of the lateral distance function (s (h)).
14. A method for production of a sewing machine needle (1), comprising: producing the sewing machine needle using a tool movement exclusively in an elevational direction (H) and/or a longitudinal direction (L), the sewing machine needle comprising: a blade extending in the longitudinal direction (L), a needle eye (3) that extends through the sewing machine needle (1) in an elevational direction (H), which is orthogonal to the longitudinal direction (L), a scarf portion (24) of the blade extending along the longitudinal direction (L), the scarf portion (24) comprising a scarf (16); at least one recess (5) formed in the blade configured to reduce friction between the blade (2) and a fabric, wherein the at least one recess (5) extends outside of the scarf portion (2) in the longitudinal direction (L) and, which is delimited in the elevational direction (H) by an upper edge (6) and a lower edge (7), wherein an upper edge distance (O) corresponding to a distance in a lateral direction (B) between the upper edge (6) of the at least one recess (5) and a position of an axis (12) of the needle eye (3) in the lateral direction (B), differs from a lower edge distance (U), the lower edge distance (U) corresponding to a distance in the lateral direction (B) between the lower edge (7) of the at least one recess (5) and the position of the axis (12) of the needle eye (3) in the lateral direction (B).
15. The method for production of a sewing machine needle according to claim 14, further comprising producing the at least one recess (5) by a separating process-or by a forming process.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows a sewing machine needle (1) with a recess (5).
(2) FIG. 2 shows the same sewing machine needle (1) as FIG. 1 as viewed after turning it by 180 about the needle axis.
(3) FIG. 3 shows a side view of the sewing machine needle (1) with a recess (5).
(4) FIG. 4 shows the A-A section through the sewing machine needle (1) from FIG. 3 in a plane defined by the lateral (B) and elevational (H) directions.
(5) FIG. 5 shows the same section as FIG. 4 and the progression of the lateral distance function s(h).
(6) FIG. 6 shows the B-B section through the sewing machine needle (1) from FIG. 3 and FIG. 4 in a plane defined by the elevational direction (H) and the longitudinal direction (L).
(7) FIG. 7 shows a section through the sewing machine needle (1) at the position of the needle eye (3).
(8) FIG. 8 shows a variety of needle blanks (8) and the reduction in their cross sections by recesses (5) and thread grooves (4).
(9) FIG. 9 shows a section through a sewing machine needle (1) and a textile fabric (29) with a needle hole (28).
(10) FIG. 10a shows a first progression variant of the lateral distance function s(h) in the area of a recess (5).
(11) FIG. 10b shows a second progression variant of the lateral distance function (h) in the area of a recess (5).
(12) FIG. 10c shows a third progression variant of the lateral distance function s(h) in the area of a recess (5).
(13) FIG. 10d shows a fourth progression variant of the lateral distance function s(h) in the area of a recess (5).
DETAILED DESCRIPTION
(14) FIG. 1 shows a three-dimensional view of a sewing machine needle 1 with a recess 5 (a second recess 5 is obscured in this view). The sewing machine needle 1 comprises a clamping portion 18, a transition portion 19, a blade portion 23, a principal blade portion 22, a uniformly shaped section 37, a scarf 16 and a needle eye 3. The axis 12 of the needle eye 3 runs in the elevational direction H. In the lateral direction B, it is located exactly in the centre between the two side walls 9 of the needle eye 3. In this embodiment, the uniformly shaped section 37 corresponds to the principal blade portion 22, i.e. the two portions overlap completely. In other embodiments of the teaching according to the invention it may be advantageous for the principal blade portion 22 and the uniformly shaped section 37 to overlap only partially. The uniformly shaped section does not overlap here with the scarf portion 24.
(15) FIG. 2 shows the sewing machine needle from FIG. 1 as viewed after turning it by 180 about the longitudinal axis 17. On the underside of the sewing machine needle 1, pointing in the negative elevational direction H, a thread groove 4 extends in the longitudinal direction L from the needle eye 3 into the transition portion 19. Thus, in the longitudinal direction L, the thread guide 4 overlaps with the blade portion 23 and the transition portion 19.
(16) FIG. 3 shows a side view of the sewing machine needle 1 with a clamping portion 18, a blade portion 23 and a tapering portion 20. It is to advantage for all embodiments of the needle if a shank 25 is disposed in the clamping portion 18. In all embodiments, the clamping portion 18 is suitable to be received in a sewing machine and driven longitudinally producing a sewing motion. The blade portion 23 is the portion within which the blade 2 extends in the longitudinal direction. It comprises a principal blade portion 22 and a scarf portion 24. Looking in the longitudinal direction L towards the needle eye 3, the principal blade portion 22 precedes the scarf portion 24. The scarf portion 24 is the portion within which the scarf 16 extends in the longitudinal direction L. In the principal blade portion 22, the blade 2 has a uniform cross section along the longitudinal direction L. Persons skilled in the art use the term cylindrical here. It may be equally advantageous for all embodiments of the invention if, in the principal blade portion 22, the cross section of the blade 2 decreases in the longitudinal direction L towards the needle eye 3. Persons skilled in the art then describe the blade as being conical. The blade portion 23 has a smaller cross section than the clamping portion 18. A conical transition area 19 between the clamping portion 18 and the blade portion 23, or the principal blade portion 22, equalises this difference in cross section between the clamping portion 18 and the blade portion 23. Looking in the longitudinal direction L away from the clamping portion 18, a tapering portion 20 adjoins the blade portion 23. In this portion, the needle's cross section decreases monotonically and terminates with the needle point 21. Located in the blade portion 23 is a recess 5, a section of which, in the longitudinal direction L, also overlaps with the transition portion 19. The recess comprises a uniformly shaped section 37 that overlaps entirely with the principal blade portion 22. The uniformly shaped section 37 is delimited in the longitudinal direction L at the same positions as the principal blade portion 22. However, in other embodiments of the teaching according to the invention, the limits defining the uniformly shaped section 37 may deviate from those defining the principal blade portion 22. The recess 5 is delimited in the elevational direction by the upper edge 6 and the lower edge 7. It is also advantageous for all embodiments if the recess 5 lies fully within the blade portion 23i.e. both the beginning and end of the recess 5 in the longitudinal direction L lie within the blade portion 23. In the longitudinal direction, the recess 5 overlaps with the scarf 16 by the overlap length 26. A section of the recess is thus also in the scarf portion 24. In this example, the overlap length 26 corresponds to 90% of the scarf length 27 in the longitudinal direction L. It is advantageous for all embodiments, however, if the overlap length 26 is at least 10% of the scarf length 27, preferably at least 70% thereof. It may be equally advantageous for sewing machine needles 1 according to the invention if the recess 5 does not overlap with the scarf 16 in the longitudinal direction L.
(17) FIG. 4 shows the A-A section through a sewing machine needle 1 at the position shown in FIG. 3. In the longitudinal direction L, the section is located at the end of the blade portion 23, directly before the transition portion 19 commences. It thus shows the cross section of the blade 2 which is furthest from the needle eye 3 in the longitudinal direction L. The blade 2 has two recesses 5 and a thread groove 4. The recesses 5 reduce the cross section of the blade 2 and have a concave shape in the sectional plane. Behind the sectional plane, the shank 25 is visible, which has a larger cross section than the blade 2. The upper edge 6 and lower edge 7 are cut by the sectional plane and delimit the recesses 5 in the elevational direction H both upwardly and downwardly. FIG. 4 also shows the position, in the lateral direction, of the axis 12 of the needle eye 3. In the lateral direction B, each of the upper edges 6 is spaced from the axis 12 of the needle eye 3 by an upper edge distance O. In the lateral direction B, each of the lower edges 7 is spaced from the axis 12 of the needle eye 3 by a lower edge distance U. The upper edge distance O and the lower edge distance U differ in magnitude: in this case, the upper edge distance O is smaller than the lower edge distance U. The recess height 11, which, in all embodiments of the invention, corresponds to the distance between the upper edge 6 and the lower edge 7 in the elevational direction H, is more than 30% of the shank height 10 of the blade 2 in the elevational direction H. In the lateral direction, the surface 13 of the sewing machine needle 1 is spaced from the position of the axis 12 of the needle eye 3 by the lateral distance s. The lateral distance s may be described by a lateral distance function s(h), which is dependent on the height coordinate h in the elevational direction, i.e.
(18) s=f(h)=s(h). A lead-in tangent 14 which adjoins the curve of the lateral distance function s(h) tangentially at the upper edge 6 of the recess 5, in the end area thereof, encloses a lead-in angle 15 greater than 5 with the elevational direction H. However, the selection ranges for the lead-in angle 15 which have been mentioned in the earlier paragraphs are advantageous for all embodiments of the sewing machine needle 1.
(19) FIG. 5 depicts the same section as FIG. 4 and shows, once again, the lateral distance function s(h). The upper edge distance O corresponds to the value of the lateral distance function s(h) at the height coordinate h.sub.O of the upper edge 6, i.e. O=s(h.sub.O). The lower edge distance U corresponds to the value of the lateral distance function s(h) at the height coordinate h.sub.U of the lower edge 7, i.e. U=s(h.sub.U). In this embodiment, the lateral distance s decreases strictly monotonically within the elevational reach of the recess 5 as the height coordinate increases in the elevational direction. Over the entire recess height 11, therefore, it holds that the derivative of the lateral distance function s(h) is less than zero (s(h)<0 for h.sub.O>h>h.sub.U). A curve progression of this kind may be advantageous for all the embodiments. In just the same way, it is also advantageous for all variants if the lateral distance decreases monotonically with increasing height, i.e. the derivative of the lateral distance function s(h) is less than or equal to zero (s(h)0 for h.sub.O>h>h.sub.U). The second derivative of the lateral distance function s(h) for height coordinates smaller than the height coordinate h.sub.U of the lower edge 7 and for height coordinates larger than the height coordinate h.sub.O of the upper edge 6 is less than zero (s(h)<0 if h>h.sub.O or h<h.sub.U).
(20) FIG. 6 shows the section B-B through the sewing machine needle 1 in a plane defined by the axis 12 of the needle eye 3 and the longitudinal direction L. The position of the section B-B is also shown in FIG. 4. The needle eye 3 is located in the tapering portion 20 of the sewing machine needle 1. In the longitudinal direction, the axis 12 of the needle eye 3 lies centrally in the needle eye 3. Behind the sectional plane, as seen by the observer, the needle eye 3 is delimited in the lateral direction B by a side wall 9. On the underside of the sewing machine needle 1, a thread groove 4 adjoins the needle eye 3. The needle eye 3 and the thread groove 4 are not spaced from one another in the longitudinal direction L but merge into each other. The thread groove 4 runs through the entire blade portion 23 and ends within the transition portion 19. The thread groove 4 is a depression in the blade 2 of the sewing machine needle 1 and is suited to receive a sewing thread during the sewing process. A large variety of thread grooves 4 have been known for many years to persons skilled in the art. The teaching according to the invention can be combined to advantage with every form and shape of thread groove 4.
(21) FIG. 7 shows the same section C-C through a sewing machine needle 1 as FIG. 6 at the position of the needle eye 3 in a plane defined by the elevational direction H and the lateral direction B. The position of the section C-C is indicated in FIG. 6. In the lateral direction B, the needle eye 3 is delimited on each side by a side wall 9. In the lateral direction B, the axis 12 of the needle eye 3 runs exactly centrally through the needle eye 3. The axis 12 of the needle eye 3 has this position in the lateral direction B in all other embodiments of the invention as well. Also visible, on the underside of the sewing machine needle 1, is the thread groove 4, which directly adjoins the needle eye 3.
(22) FIG. 8 shows possible shapes for a needle blank 8 and a possible arrangement of recesses 5 for each shape. The cross section of the needle blank 8 may be round 32, oval 33, trapezoidal 34, triangular 30 or triangular with rounded corners 31. The needle blank may, however, also have a cross-sectional shape 35 consisting of two arcs having different radii and two obliquely oriented straight lines which connect the arcs with each other. It is evident from the second column of FIG. 8 how recesses 5 according to the invention reduce the cross section of needle blanks 8 having these shapes. The third column of FIG. 8 shows how a thread groove 4 reduces the cross section of needle blanks 8 having these shapes. The teaching of the invention may also be used to advantage for needle blanks 8 having all other already-known cross-sectional shapes for sewing machine needles 1.
(23) FIG. 9 shows a section through a sewing machine needle 1 and a fabric 29 at the position of a needle hole 28 in the textile fabric 29. The fabric 29 is not in contact with the sewing machine needle 1 in the area of the recesses 5. Here, therefore, there can be no friction, resulting in a reduction in the overall friction between the sewing machine needle 1 and the fabric 29. The needle hole 28 is shown in FIG. 9 as an idealised circle. Other shapes may be obtained for the needle hole 28 depending on the textile and mechanical properties of the fabric 29 and the shape of the needle's cross section. However, all of these have in common that, in the area of the recesses 5, the fabric 29 and the sewing machine needle 1 are not in mutual contact.
(24) FIGS. 10a to 10d show four alternative cross-sectional shapes for the recess 5 in a sewing machine needle 1, and the corresponding progression of the lateral distance function s(h). These alternative cross-sectional shapes can be combined advantageously with all possible embodiments of the invention. In the embodiment of FIG. 10a, the lateral distance function s(h) between the upper edge 6 and the lower edge 7 of the recess 5 is made up of two straight lines with different gradients, neither of which equals 0. In the embodiment of FIG. 10b, the lateral distance function s(h) between the upper edge 6 and the lower edge 7 of the recess 5 is made up of five straight lines. Mutually contiguous straight lines have different gradients, neither of which equals zero. In the embodiment of FIG. 10c, the lateral distance function s(h) between the upper edge 6 and the lower edge 7 of the recess 5 is made up of three circular arcs. FIG. 10d shows an embodiment having a lateral distance function s(h) made up of a circular arc and a straight line that adjoins this arc in the positive elevational direction H. The transition point 36 between the straight line and the arc is depicted in the drawing: the circular arc commences at the lower edge 7 in the positive elevational direction H and ends at a transition point 36. At this transition point 36, the straight line adjoins the circular arc tangentially, continues in the positive elevational direction H and ends at the upper edge 6.
(25) TABLE-US-00001 List of reference numerals 1 Sewing machine needle 2 Blade 3 Needle eye 4 Thread groove 5 Recess 6 Upper edge of recess (5) 7 Lower edge of recess (5) 8 Needle blank 9 Side wall of needle eye (3) 10 Blade height 11 Height of recess (5) 12 Axis of needle eye (3) 13 Surface of sewing machine needle (1) 14 Lead-in tangent 15 Lead-in angle 16 Scarf 17 Longitudinal axis 18 Clamping portion 19 Transition portion 20 Tapering portion 21 Needle point 22 Principal blade portion 23 Blade portion 24 Scarf portion 25 Shank 26 Overlap length 27 Length of scarf (16) 28 Needle hole 29 Fabric 30 Needle blank 8 with triangular cross section 31 Needle blank 8 with triangular cross section and rounded corners 32 Needle blank 8 with round cross section 33 Needle blank 8 with oval cross section 34 Needle blank 8 with trapezoidal cross section 35 Needle blank 8 with a cross-sectional shape consisting of two circular arcs and two straight lines 36 Transition point 37 Uniformly shaped section of recess (5) B Lateral direction L Longitudinal direction H Elevational direction h Height coordinate s Lateral distance s(h) Lateral distance function dependent on height coordinate (h) O Upper edge distance U Lower edge distance h.sub.O Height coordinate at the level of the upper edge 6 h.sub.U Height coordinate at the level of the lower edge 7
