JET STRIP FOR A TEXTILE PROCESSING MACHINE

Abstract

A nozzle channel (24) of a jet strip (18) extends from the first side (20) to the second side (22) of the jet strip (18) and defines a flow-through direction (30, 38). A second section (28) of the nozzle channel (24) is offset relative to a first section (26) in the direction transverse to the flow-through direction (30, 38). Preferably, the nozzle channel (24) is funnel-shaped, with a middle section (50) tapering in the direction from the first side (20) to the second side (22) and with a single asymmetrically arranged funnel neck that is formed by the second section (28

Claims

1. A jet strip (18) for a textile processing machine, the jet strip (18) comprising: a first side (20) and a second side (22), and a nozzle channel (24) that defines one or both of a first flow-through direction (30) and a second flow-through direction (38) and that has a first section (26) and a second section (28), the nozzle channel (24) extending from the first side (20) to the second side (22), and the second section (28) being offset relative to the first section (26) in a direction transverse to one or both of the first flow-through direction (30) and the second flow-through direction (38).

2. A jet strip (18) according to claim 1, wherein the first section (26) and the second section (28) each define a central axis (68, 70), the central axis (68) of the first section (26) being offset in parallel to the central axis (70) of the second section (70).

3. A jet strip (18) according to claim 1, wherein the first section (26) has a diameter (52) and wherein the second section (28) has a diameter (54), the offset between the first section (26) and the second section (28) being less than or equal to half the difference of the diameter (52) of the first section (26) and the diameter (54) of the second section (28).

4. A jet strip (18) according to claim 1, wherein the first section (26) is longer in one or both of the first flow-through direction (30) and the second flow-through direction (38) than the second section (28) is.

5. A jet strip (18) according to claim 1, wherein the first section (26) and the second section (28) have a middle section (50) arranged between them, the middle section (50) having a middle section wall surface (64) that borders the middle section (50) in a direction transverse to the first flow-through direction (30), and wherein the middle section (50) of the nozzle channel (24) tapers in the first flow-through direction (30).

6. A jet strip (18) according to claim 5, wherein the middle section wall surface (64) is set up to form an asymmetric guiding surface (86, 88) for fluid in the nozzle channel (24) in the first flow-through direction (30).

7. A jet strip (18) according to claim 5, wherein the middle wall surface (64) has a first guiding surface section (86) and a second guiding surface section (88), the second guiding surface section (88) having a greater extension (92) in the first flow-through direction (30), and wherein an end of the second guiding surface section (88) being after the first guiding surface section (86) in the first flow-through direction (30).

8. A jet strip (18) according to claim 5, wherein a longitudinal section cut through the middle section wall surface (64) of the nozzle channel (24) monotonically decreases over an entirety from the first section (26) to the second section (28).

9. A jet strip (18) according to claim 5, wherein the first section (26) has a first wall surface (60), the second section (28) has a second wall surface (62), and the middle section (50) has a middle section wall surface (64) that borders the middle section (50) in the direction transverse to the one or both of the first flow-through direction (30) and the second flow-through direction (38) and wherein one or both of: a transition (82) between the second wall surface (62) and the middle section wall surface (64) has a reflex angle (80), and a transition (100) between the first wall surface (60) and the middle section surface (64) has an obtuse angle (78).

10. A jet strip (18) according to claim 5, wherein the middle section (50) is bordered by a lateral surface of a frustum of cone, wherein a central axis (68) that is defined by the frustum of cone lateral surface coincides with a central axis (68) that is defined by the first section (26).

11. A jet strip (18) according claim 5, wherein the middle section (50) has an aperture angle (56) of 110 to 175.

12. A jet strip (18) according to claim 1, wherein the jet strip (18) has a hardened surface in or near the second sections (28) on the second side (22).

13. A jet strip (18) according to claim 1, wherein the second section (28) is offset in the longitudinal extension direction (42) and/or a transverse extension direction (44) of the jet strip.

14. A jet strip (18) according to claim 1, wherein the first section (26) and the middle section (50) are produced by drilling a hole in a strip material.

15. A manufacturing process (116) for a jet strip (18) according to claim 1, the process (116) comprising: Preparing (118) a material with a first side and a second side; Producing (120) a first recess comprising a drill hole with a bottom in the material on the first side, the first recess defining a central axis; Producing (122) a second recess in the bottom of the first recess by one or more of punching, shearing, working, indentation, or stamping, this second recess being offset in a direction transverse to the central axis.

Description

[0049] The schematic illustrations are as follows:

[0050] FIG. 1aa jet beam with an inventive jet strip in a first usage position;

[0051] FIG. 1bthe jet beam from Figure la with an inventive jet strip in a second usage position;

[0052] FIG. 2top view of an inventive jet strip;

[0053] FIG. 3across sectional illustration of the inventive jet strip according to FIG. 2;

[0054] FIG. 3ba cross section through the nozzle channel of the jet strip according to FIG. 3a;

[0055] FIG. 3ca detail of FIG. 3a;

[0056] FIG. 3da cross section through a nozzle channel of an alternative inventive jet strip; and

[0057] FIG. 4a schematic representation of the inventive process.

[0058] FIG. 1a shows a jet beam 10 with a recess 12 on the pressure side 14 of the jet beam 10 for a textile processing machine. The recess 12 has a support surface 16. The recess 12 has an inventive jet strip 18 arranged in it that has a first side 20 and a second side 22. The surfaces of the first side 20 and the second side 22 are preferably parallel to one another. In a first usage position, the jet strip 18 lies with the surface of its second side 22 on the support surface 16, which is set up to support the jet strip 18 if pressurized water impinges on the pressure side 14 of the jet beam 10, and thus on the first side 20 of the jet strip 18. The jet strip has a nozzle channel 24 that has a first section 26 on the first side 20 of the jet strip 18 and a second section 28 on the second side 22 of the jet strip. The nozzle channel 24, in particular its first section 26 and second section 28, define(s) a first flow-through direction 30 from the first side 20 to the second side 22. With the jet strip 18 in this usage position, a jet 32 is produced that sprays early behind the second side 22 of the jet strip 18 and that strikes a random fiber web 36 or bonded textile that is moved in feed direction 34 and premoistens or post-processes, for example laminates, the web or textile. For premoistening, for example, water having a pressure of 5-30 bar can impinge on the first side 20 of the jet strip 18. For laminating, for example, water having a pressure of 5-250 bar can impinge on the first side 20 of the jet strip 18.

[0059] FIG. 1b shows a jet beam 10 according to FIG. 1a with an inventive jet strip 18 in a second usage position; Please refer to the above description accompanying FIG. 1a. Only a few differences are described below. The second usage position is the position that is opposite the first usage position in the sense that in this usage position it is the surface of the first side 20 of the jet strip 18 that lies on the support surface 16. Thus, the nozzle channel 24, in particular the first section 26 and the second section 28 of the channel, define(s) a second flow-through direction 38 from the second side 22 to the first side 20, so that the water first flows through the second section 28 and then through the first section 26. In this usage position, pressurized water impinges on the jet beam 10 from the pressure side 14, and thus pressurized water impinges on the second side 22 of the jet strip 18. Thus, in this usage position a bonding jet 40 is produced that strikes the web 36 of premoistened and/or prebonded random fiber or textile and entangles its fibers with one another. For bonding, for example, a pressure of 10-450 bar can impinge on the second side 22 of the jet strip 18. A sealing means (not shown) ensures that water cannot flow between the support surface 16 and the jet strip in any of the usage positions, but rather only through the nozzle channels.

[0060] FIG. 2 shows a top view of an inventive jet strip 18, looking down onto the surface of the first side 20. The jet strip 18 has a longitudinal extension 42 (length) and a transverse extension 44 (width) that define a longitudinal extension direction 42 and a transverse extension direction 44. The length can be, for example, several meters and the width can be, for example, a few centimeters. The jet strip 18 has a thickness of 1 mm, for example. Preferably the jet strip 18 has multiple nozzle channels 24 arranged one after the other in a row in the longitudinal extension 42. It is also possible for multiple rows to be arranged next to one another. The jet strip 18 is made in a single piece. It is also possible for the jet strip to be composed of multiple sections. The jet strip can consist of, for example, metal or ceramic, or it can have the mentioned materials.

[0061] FIG. 3a shows a cross section of the inventive jet strip 18 from FIG. 2, cut through the plane A-A. FIG. 3b shows a cross section of the nozzle channel 24 cut through the plane B-B from FIG. 3a. FIG. 3c shows a detail C of FIG. 3a. For a general description of the jet strip 18 in FIG. 3a, please additionally refer to the explanations for FIGS. 1a, 1b, and 2.

[0062] The unbranched nozzle channel 24 passing through the jet strip 18 extends from a first orifice 46 on the first side 20 all the way to a second orifice 48 on the second side 22. A first section 26 of the nozzle channel 18 is arranged bordering the first orifice 46 and a second section 28 is arranged bordering the second orifice 48. Alternatively, one or more other sections can be arranged between the first orifice 46 and the first section 26 or between the second orifice 48 and the second section 28. Every nozzle channel 24 in the jet strip 18 has its own first section 26 with its own first orifice 46 on the first side 20 and its own second orifice 48 on the second side 22. Alternatively, multiple nozzle channels 24 can have a common first section 26. The first section 26 and the second section 28 have a middle section 50 arranged between them. The middle section 50 borders the first section 26 and the second section 28. Alternatively, there can be another section arranged between the middle section 50 and the first section 26 and/or between the middle section 50 and the second section 28.

[0063] The diameter 52 of the first section 26 is greater than the diameter 54 of the second section 28. Preferably the diameter 52 of the first section 26 is large enough that in the usage position to produce a bonding jet after the water passes through the second section 28 it is largely unaffected by the first section 26, so that it is preferably the second section 28 that essentially determines the second flow-through direction 38. The middle section 50 of the nozzle channel 24 abruptly tapers in first flow-through direction 30 from the first side 20 to the second side 22. The aperture angle 56 of the middle section 50 is preferably no more than 175, more preferably 110 to 175.

[0064] In the direction transverse to the first flow-through direction 30, the nozzle channel 24 is bordered by an undercut-free channel wall 58. In particular, in the direction transverse to the flow-through direction 30 the nozzle channel 24 is bordered by the first wall surface 60 of the first section 26, the second wall surface 62 of the second section 28, and the middle section wall surface 64 of the middle section 50.

[0065] The first wall surface 60 is, for example, a lateral surface of a cylinder or a frustum of cone, these being examples of a first wall surface 60 that is preferably generally a section of a surface of revolution this section being is closed in the peripheral direction 66 around the first flow-through direction 30 and/or the second flow-through direction 38.

[0066] The second wall surface 62 of the second section 28 is, for example, a section of a lateral surface of a cylinder or a frustum of cone, this section being closed in the peripheral direction 66, these being examples of a second wall surface 62 that is preferably generally a section of a surface of revolution, this section being closed in the peripheral direction 66 around the first flow-through direction 30 and/or the second flow-through direction 38.

[0067] In the sample embodiment according to FIG. 3a, the middle section wall surface 64 is a section of lateral surface of a frustum of cone, this section being closed in the peripheral direction 66 around the first flow-through direction 30. The middle section wall surface 64 can also be, for example, another section of a surface of revolution, for example of a lateral surface of a frustum of cone, this section being closed in the peripheral direction 66 around the first flow-through direction 30. The frustum of cone shape means that the middle section wall surface 64 in the longitudinal section shown is straight through the nozzle channel 24, and thus the middle section wall surface 64 monotonically drops off in the first flow-through direction 30 from the first side 20 to the second side 22.

[0068] In one embodiment in which the first wall surface 60 and/or the second wall surface 62 are bordered by a conical wall, the aperture angle of the first wall surface 60 and/or the second wall surface 62 is/are preferably less than the aperture angle 56 of the middle section wall surface. In one embodiment in which the first section 26 and/or the second section 28 widen, the first section 26 and/or the second section 28 preferably widen(s) in the second flow-through direction 38 from the second side 22 to the first side 20.

[0069] The second section 28 is arranged offset relative to the first section 26 and, in the embodiment in FIG. 3a, also relative to the middle section 50, in the direction transverse to the first flow-through direction 30 and the second flow-through direction 38. It is possible to speak of a nozzle 28 arranged asymmetrically to the first section 26 and to the middle section 50. This is explained below using the central axis 68 of the first wall surface 60 defined by the first wall surface 60 and the central axis 70 of the second wall surface 62 defined by the second wall surface 62.

[0070] The first wall surface 60, the second wall surface 62, and/or the middle section wall surface 64, being sections of a surface of revolution that are closed in the peripheral direction 66, can each define an axis of rotation. The axis of rotation can be, for example, an axis of a cylinder or a frustum of cone, if the surfaces are sections of such a surface of revolution. The first section 26, the second section 28, and/or the middle section 50 can each define a central axis by the respective axis of rotation. In a preferred embodiment, the first section 26 and the middle section 50 define a common central axis 68. The central axis of the first section or the middle section 68 is preferably oriented transverse to the surface of the first side 20 and/or the second side 22. The central axis of the second section 70 is preferably oriented transverse to the surface of the first side 20 and/or the second side 22.

[0071] The central axis of the first section 68 and/or the central axis of the middle section 68 can serve as a reference axis for indicating an offset direction 72 of the offset and an offset distance 74 of the second section 28 relative to the first section 26 and/or the middle section 50. It is especially preferred if the central axis 70 defined by the second section 28 is offset, preferably offset in parallel, in an offset direction 72 relative to the common reference axis defined, for example, by the first section 26 and the middle section 50. In the sample embodiment the offset direction 72 of the second section 28 of the nozzle channel 24 shown is parallel to the transverse extension of the jet strip 18. Thus, the offset direction 72 lies in the plane of projection of FIGS. 3a and 3c. The offset direction 72 can generally point in the direction defined by the longitudinal extension 42 and/or in the direction defined by the transverse extension 44. It is possible to define one offset direction 72 for the second sections 28 of the nozzle channels 24 in the jet strip 18 according to FIG. 2, or to define multiple offset directions 72 for the second sections 28 of the nozzle channels 24. The nozzle channels 24 of the jet strip 18 of FIG. 2 can be the same except for the offset direction 72 of the offset between the first section 26 and the second section 28. However, the offset direction 72 can also, for example, be the same for all nozzle channels 24.

[0072] The offset distance 74 can be, for example, between a minimum of 0.01 mm and a maximum of 0.3 mm. The diameter 52 of the first section 26 can be, for example, between a minimum of 0.26 mm and a maximum of 1 mm. The diameter 54 of the second section can be, for example, between a minimum of 0.05 mm and a maximum of 0.2 mm. The offset distance 74 of the recess centers or the central axes of the first section 68 and the central axis of the second section 70 in the direction transverse to the flow-through direction 30 is, in any case, greater than the manufacturing tolerance of the first section 26 and the second section 28 with respect to one another. The manufacturing tolerance can be 0.006 mm, for example.

[0073] The offset distance 74 of the central axis of the first section 68 and the central axis of the second section 70 in the offset direction 72 is preferably less than or equal to half the difference of the diameter 52 of the first section and the diameter 54 of the second section. In the embodiment shown, the projection 76 of the second orifice 48 and the second wall surface 62 in the direction opposite the first flow-through direction 30 and onto the first side lies within the first orifice 46 and within the second wall surface 62. This produces a nozzle channel that is free of bends with simplified manufacturing.

[0074] In the embodiment shown, the central axis 68 of the first section 26 or the common central axis 68 of the first section 26 and of the middle section 50 and the central axis of the second section 70 stand transverse to the surface of the first side 20 and to the surface of the second side 22.

[0075] In the cutting plane shown in FIG. 3a, this cutting plane containing the central axis 68 of the first section, the middle section wall surface 64 is arranged at an obtuse angle 78 relative to the first wall surface 60. Alternatively, the middle section wall surface 64 can also be arranged at an angle of 180 to the first wall surface 60. In such an embodiment, the first section 26 can be in the form of a conical widening that abuts, preferably seamlessly, the middle section 50. The middle section wall surface 64 can also be arranged at an angle greater than 180 to the first wall surface 60. In the cutting plane shown in FIG. 3a, the second wall surface 62 is preferably arranged at a reflex angle 80 relative to the middle section wall surface 64.

[0076] In the embodiment shown, a second transition edge 82 is created between the middle section wall surface 64 and the second wall surface 62, this second transition edge 82 being defined by the curve of intersection of the imaginary continuation, in second flow-through direction 38, of the cylinder lateral surface bordering the second section 28 and the imaginary continuation, in first flow-through direction 30, of the frustum of cone lateral surface bordering the middle section 50.

[0077] In the embodiment shown, the middle section wall surface 64 forms an asymmetric guiding surface that is effective when fluid impinges on the nozzle channel 24 from the first side, this asymmetric guiding surface guiding the fluid, from the areas at the first wall surface 60 when the flow through the nozzle channel is in the first flow-through direction 30, to the asymmetrically arranged confluence 84 (opening) in the middle section wall surface 64, which is bordered by the transition edge 82, and into the second section 28. The guiding surface has a first guiding surface section 86 that is arranged in offset direction 72 transverse to the first flow-through direction 30, and a second guiding surface section 88 that is arranged transverse to the first flow-through direction 30 with respect to the first guiding surface section 86. The guiding surface sections 86, 88 are arranged in the fluid flow path defined by the first section 26. The extension 90 of the first guiding surface section 86 in the first flow-through direction 30 is preferably smaller than the extension 92 of the second guiding surface section 88 in the first flow-through direction 30. The extension 94 of the first guiding surface section 86 transverse to the first flow-through direction 30, in offset direction 72, is preferably smaller than the extension 96 of the second guiding surface section 88 transverse to the first flow-through direction 30, in offset direction 72. The first guiding surface section 86 and the second guiding surface section 88 can begin, for example, at the transition, defined by the first section 26 and the middle section 50, between the first wall surface 60 and the middle section wall surface 64, at the same beginning distance 98 to the first orifice 46 or the surface 20 on the first side. However, the end of the second guiding surface section 88 is preferably downstream in the first flow-through direction 30, after the first guiding surface section 86. Along the first flow-through direction 30, guiding surface sections 86, 88 are formed that are arranged at an offset, these guiding surface sections defining two offset steps of the cross sectional tapering of the flow-through channel.

[0078] The offset steps can partly break up a uniform flow through the nozzle channel 24, or cause it to swirl, which can produce an especially early spraying jet 32.

[0079] At the first transition 100 from the first wall surface 60 to the middle section wall surface 64 it is possible to form a curvature 102 of the first transition 100. Preferably, the curvature has a constant radius in the peripheral direction. Accordingly, an asymmetry of the nozzle channel 24 can preferably remain limited to the arrangement of the second section 28 relative to the first section 26 and the middle section 50, and possibly to the second transition 82.

[0080] At the second transition edge 82 from the middle section wall surface 64 to the second wall surface 62 it is possible to form a curvature 104. The curvature 104 can have different radii of curvature along the periphery of the second transition edge 82. In particular, in the case of nozzle channels 24, whose second sections 28 have been produced by working, indentation, stamping, punching, or shearing, a rollover 104 can be formed at the second transition edge 82. In one embodiment, the second transition edge 82 has, in a first transition edge section 106 arranged lying in offset direction 72, a radius of curvature or rollover that is greater than the radius of curvature or rollover of the second transition edge section 108 arranged lying opposite the offset direction 72, that is opposite the first transition edge section 106. This asymmetry can additionally affect the flow behavior.

[0081] The first transition edge section 106 lying in offset direction 72 is preferably arranged at a first distance 110 from the second orifice 48 or the surface of the second side 22, this first distance being greater than the second distance 112 of the opposite second transition edge section 108 from the second orifice 48 or the surface of the second side 22.

[0082] The second wall surface 62 preferably stands transverse to the surface 22 of the jet strip on the second side. The second orifices 48 have a hardening coating 114 arranged around them. It is also possible for the jet strip material to be hardened.

[0083] This makes the jet strip shown especially suitable for the usage position for producing a spraying jet and for the usage position for producing a bonding jet.

[0084] FIG. 3d shows another sample embodiment of a jet strip 18 with a nozzle channel 24 whose second section 28 is asymmetrically arranged with respect to the first section 26 and the middle section 50. Particularities of this sample embodiment are explained below. In other respects, the explanations and reference numbers for the sample embodiment are the same as for the other figures. In this sample embodiment, the first wall surface 60 changes into the middle section wall surface 64 at an angle of 180. In particular both the first wall surface 60 and the middle section wall surface 64 are bordered by a section of a lateral surface of a frustum of cone, this section being closed in the peripheral direction, and both have the same aperture angle 56. The design of the first section 26 means that the jet strip 18 according to the sample embodiment in FIG. 3d might possibly be thinner than the jet strip 18 in the other sample embodiments. This can make it necessary, for example, for the surface of the first side 20 and/or the surface of the second side 22 to have one or more supporting layers (not shown) arranged on it and connected with the jet strip 18.

[0085] The jet strip according to FIGS. 1 through 3d is preferably made in one piece. It is also possible for the jet strip 18 to be composed, for example, of multiple layers laid on top of one another. For example, the first section 26 can be arranged in one layer and the middle section 50 and the second section 28 can be arranged in another layer.

[0086] FIG. 4 is a schematic representation of a manufacturing process 116 for the inventive jet strip 18, for example from FIGS. 1 through 3d.

[0087] In one step 118, a strip material is prepared. The strip material can be a hardened material, for example hardened steel. The strip material can be hardened on the second side. The strip material can have a hardened surface on the second side of a jet strip due to a coating.

[0088] In another step 120, a first recess is arranged in a first side of the strip material, this first recess having a first diameter and a bottom. This creates a first orifice 46 on the surface of the first side 20 and a first recess. The first recess can be created, for example, by drilling a hole or by lasing or by electrical discharge machining. The drill hole axis or the working axis of the laser or electrical discharge machining device can define a central axis 68 for the first recess. The first recess preferably forms the first section 26 and the middle section 50 in the completed jet strip 18.

[0089] In another step 122, a second recess is made in the bottom and in the second side 22. It is especially preferred for the second recess in the bottom and in the second side to be produced by punching, shearing, working, indentation, or stamping. It is preferred if the working section of the tool for producing the second recess, for example the working section of a punching die or an indentation tool, is arranged for this purpose in the first recess and used to produce the second recess. The working section of the tool for producing the second recess, for example the punching die or the indentation tool, preferably has an axis of symmetry, and it is preferable if this axis of symmetry of this working section is arranged offset in parallel to the central axis of the first recess. The second recess can also be created by drilling a second hole in the bottom of the first recess in the second side.

[0090] The strip material can be post-processed in another step 124. This can involve grinding or polishing the strip material, for example on the second side.

[0091] The surface of the second side can have a hardening coating applied to it. In one sample embodiment in which the second orifice 48 or the edge at the second orifice 48 has already been produced by arranging 122 the second recess, or in which the second orifice 48 only arises in a subsequent processing step, for example by grinding the second side, the area around the second orifice 48 or the edge at the second orifice 48 can be processed by grinding, polishing, and/or by applying a hardening coating.

[0092] A jet strip 18 for producing a spraying jet and a manufacturing process 116 for the jet strip 18 are indicated. A nozzle channel 24 of the jet strip 18 extends from the first side 20 to the second side 22 of the jet strip 18 and defines a flow-through direction 30, 38. A second section 28 of the nozzle channel 24 is offset relative to a first section 26 in the direction transverse to the flow-through direction 30, 38. Preferably, the nozzle channel 24 is funnel-shaped, with a middle section 50 tapering in the direction from the first side 20 to the second side 22 and with a single asymmetrically arranged funnel neck that is formed by the second section 28. The jet strip 18 can be created, for example, by drilling a hole 120 with a conically tapering bottom in a strip material and by producing 122 a recess in the bottom of the drill hole using a die or an indentation tool, with the drill hole and the recess having central axes that are offset in the transverse direction.

TABLE-US-00001 List of reference numbers: 10 Jet beam 12 Recess in jet beam 14 Pressure side 16 Support surface 18 Jet strip 20 First side/surface of first side 22 Second side/surface of second side 24 Nozzle channel 26 First section 28 Second section, nozzle 30 First flow-through direction 32 Early spraying jet 34 Feed direction 36 Random fiber web, bonded textile 38 Second flow-through direction 40 Bonding jet 42 Longitudinal extension 44 Transverse extension 46 First orifice 48 Second orifice 50 Middle section 52 Diameter of first section 54 Diameter of second section 56 Aperture angle 58 Channel wall 60 First wall surface 62 Second wall surface 64 Middle section wall surface 66 Peripheral direction 68 Central axis of first section/of middle section 70 Central axis of second section 72 Offset direction 74 Offset distance 76 Projection 78 Obtuse angle 80 Reflex angle 82 Second transition edge/second transition 84 Confluence/opening 86 First guiding surface section 88 Second guiding surface section 90 Extension of first guiding surface section lengthwise 92 Extension of second guiding surface section lengthwise 94 Extension of first guiding surface section transverse 96 Extension of second guiding surface section transverse 98 Beginning distance 100 First transition 102 Curvature 104 Curvature/rollover 106 First transition edge section 108 Second transition edge section 110 First distance 112 Second distance 114 Coating 116 Manufacturing process 118 Preparing 120 Drilling a hole 122 Producing a second recess 124 Post-processing