razor cartridge

Abstract

A sub-assembly for a razor cartridge, the sub-assembly comprising: a base (30) comprising a front wall (34) having a top surface (36) and a rear wall (35) having a top surface (37); a plurality of blades mounted to the base between the front wall and the rear wall, each blade having a cutting edge; a guard fastened to the base, the guard having an upper skin contacting surface and a front face, the upper skin contacting surface and the front face being defined by a plurality of ribs forming a plurality of open slots; wherein the top surface on the front wall of the base is positioned at a vertical distance of at least 0.5 mm below the cutting edges, the front face of the guard being in front of the front wall of the base; wherein the upper skin contacting surface and the front face of the guard meet at an outer angle of 45 degrees to 85 degrees; the cutting edges of immediately adjacent blades being spaced apart from each other by a distance (d3, d4) of greater than 1.75 mm.

Description

[0001] This divisional application is a divisional application of Chinese patent application No. 202080024792.X (international application No. PCT / US2020 / 026079), filed on April 1, 2020, entitled "Razor Blade Holder". Technical Field

[0002] The present invention relates to wet safety razors, and more particularly to razor blade holders having a housing for protecting the skin from contact with one or more blades. Background Technology

[0003] Generally, a safety razor's blade holder or blade unit has at least one blade with a cutting edge, which moves across the surface of the skin being shaved by means of a handle to which the blade holder is attached. Some razors are equipped with a spring-biased blade holder that pivots relative to the handle to follow the contours of the skin during shaving. The blade holder can be detachably mounted to the handle so that when the blade sharpness has decreased to an unsatisfactory level, it can be replaced with a new blade holder, or permanently attached to the handle if it is desired to discard the entire razor when one or more blades have become dull. Razor blade holders typically include a guard that contacts the skin in front of one or more blades during shaving, and a top cap that contacts the skin behind one or more blades. The top cap and guard help establish what is known as "shaving geometry," that is, parameters that determine the orientation and position of the blades relative to the skin during shaving, which in turn strongly influence shaving performance and razor effectiveness. The top cap may include a water-soluble shaving aid to reduce drag and improve comfort. The guard may be generally rigid, for example, integrally formed with a frame or platform structure that supports the blade. The guard may also include a softer elastomeric material to improve skin stretch.

[0004] Furthermore, cover plates have been developed to fit onto razor blade holders to facilitate cutting hair to a specified length. These cover plates also protect the skin by raising the blades above the skin surface and thus limiting contact. However, because these cover plates are designed to be mounted on existing razor blade holders intended for shaving the skin, their trimming performance (i.e., cutting hair to a certain length) is limited and ineffective. Therefore, a safety razor is needed that can safely and effectively cut hair to a specific length. Summary of the Invention

[0005] In one aspect, the invention is generally characterized by a subassembly for a razor blade holder, the subassembly having a base comprising a front wall having a top surface and a rear wall having a top surface. At least one blade is mounted to the base between the front wall and the rear wall. At least one blade has a cutting edge positioned at least 0.5 mm above a plane tangent to the top surfaces of the front wall and the rear wall.

[0006] In another aspect, the invention is characterized substantially by a method of assembling a razor blade holder, the method comprising providing a base including a front wall having a top surface and a rear wall having a top surface. At least one blade having a cutting edge is mounted to the base between the front and rear walls. The cutting edge is positioned at least 0.5 mm above a plane tangent to the top surfaces of the front and rear walls. A retainer having multiple ribs is mounted to the base.

[0007] In another aspect, the invention is generally characterized by a razor blade holder having a base including a front wall having a top surface. A retainer is fastened to the base. The retainer has an upper skin-contact surface and a front face, the upper skin-contact surface having a plurality of ribs defining a plurality of open slots, the front face being generally transverse to the upper skin-contact surface. The front face has a lower surface interconnecting the plurality of ribs, the plurality of ribs defining a plurality of open slots extending into the front face and communicating with the open slots of the upper skin-contact surface. At least one blade is mounted to the base. The blade has a cutting edge positioned above the upper skin-contact surface and immediately adjacent to the rear of the front wall. The lower surface of the front face is positioned at a vertical distance below the cutting edge. Attached Figure Description

[0008] Other features and advantages of the invention, as well as the invention itself, can be more fully understood when the following description of various embodiments is read in conjunction with the accompanying drawings, in which: Figure 1A This is a front perspective view of a razor blade holder according to one possible embodiment of the present invention.

[0009] Figure 1B for Figure 1A Rear perspective view of the razor blade holder.

[0010] Figure 2 for Figure 1A and Figure 1B Assembly diagram of the razor blade holder.

[0011] Figure 3 for Figure 1A and Figure 1B A perspective view of a sub-component of the razor blade holder.

[0012] Figure 4 For roughly along Figure 3The cross-sectional view of the sub-component is taken from line 4-4.

[0013] Figure 5 This is a cross-sectional view of the razor blade holder, taken approximately along line 5-5 in Figure 1. Detailed Implementation

[0014] refer to Figure 1A and Figure 1B The front and rear perspective views of a razor blade holder 10 are shown, respectively. The razor blade holder 10 can be mounted to a handle (not shown). The razor blade holder 10 can be removably or permanently mounted to the handle. For example, the razor blade holder 10 can be detachably mounted to the handle to allow replacement of the razor blade holder 10 with a new one when the blade sharpness has deteriorated to an unsatisfactory level, or to permanently attach the razor blade holder to the handle if it is desired to discard the entire razor when one or more blades have become dull. The razor blade holder 10 may include a housing 12. The housing 12 may be molded from a polymer material or made of other materials such as metal. The housing 12 may have an upper skin contact surface 14 and a front face 16 transverse to the upper skin contact surface 14. The upper skin contact surface 14 may define a plurality of opening slots 18 communicating with a plurality of corresponding opening slots 20 defined by the front face 16. The opening slots 18 may extend all the way to the rear 40 ( Figure 1BThe opening slots 20 may be defined and interconnected by the lower surface 21 of the front 16. Thus, when hair contacts the front 16, it is immediately guided into the opening slots 20 (i.e., the opening slots 20 extend into the front 16). The opening slots 18 and 20 may be spaced apart by corresponding ribs 22. The ribs 22 may extend continuously downward along the upper skin contact surface 14 and down the front 16. Thus, the front may be defined by a plurality of ribs 22 and the lower surface 21 to form the opening slots 20. The ribs may have a width “w1” of about 0.25 mm to about 5 mm, and more preferably about 0.4 mm to about 1 mm. The ribs 22 may be spaced apart (i.e., the width of the slots 18 and 20) of about 0.25 mm to about 5.0 mm, and preferably about 0.7 mm to about 0.8 mm. If the spacing between adjacent ribs is too large, the blade may shave the philtrum (the vertical notch in the middle region of the upper lip) rather than cutting the hair to a certain length (e.g., the philtrum may hang loosely between the ribs 22). In some implementations, the width "w1" may be less than the distance between the ribs 22. As will be described in more detail below, the ratio of the width to the height of the ribs 22 should be sufficient to prevent the ribs 22 from breaking or deforming during use. Furthermore, the spacing of the ribs 22 (i.e., the slot width) and the width of the ribs 22 can affect the efficiency of the blade in cutting hair. For example, the widths of the slots 18 and 20 should be large enough to allow hair to pass through, and the widths of the ribs 22 should be large enough to provide sufficient strength without trapping excess hair. The dimensions of the ribs 22 also prevent skin from sagging between the ribs 22 and contacting the skin during the shaving stroke.

[0015] like Figure 2 As shown, one or more blades 24a, 24b, and 24c can be installed within the housing 12, as... Figure 2As shown. Each of the blades 24a, 24b, and 24c may have a corresponding cutting edge 26a, 26b, and 26c. The first blade 24a and the first cutting edge 26a may be adjacent to the rib 22 of the front end 16. Although three blades 24a, 24b, and 24c are shown, the razor blade holder 10 may have more or fewer blades 24, depending on the desired performance and cost of the razor blade holder 10. Opening slots 18 and 20 may extend laterally to the cutting edges 26a, 26b, and 26c. Blades 24a, 24b, and 24c may be secured to the housing 12 using one or more clamps 28a and 28b. Blades 24 may be fastened in the housing 12 or may be resiliently mounted such that the blade members 24 (e.g., the corresponding cutting edges 26) are biased against the clamps 28a and 28b. Clamps 28a and 28b help hold blades 24a, 24b, and 24c in a vertical direction (i.e., toward and away from the upper skin contact surface 14). Clamps 28a and 28b may comprise metal, such as aluminum, but plastic may also be used. Clamps 28a and 28b may also be interconnected to form a single, integrated assembly. Other assembly methods known to those skilled in the art may also be used to secure and / or mount blades 24a, 24b, and 24c to housing 12, including but not limited to wrapping, cold forming, hot riveting, insert molding, ultrasonic welding, and adhesives. As will be described in more detail below, rib 22 prevents cutting edges 26a, 26b, and 26c from contacting the skin during travel, thus cutting only hair and not skin.

[0016] refer to Figure 2 The diagram shows an assembly drawing of the razor blade holder 10.

[0017] In some embodiments, housing 12 may comprise a two-piece assembly. For example, housing 12 may comprise a base 30 (e.g., a lower portion) and an ibta retainer 32 (e.g., an upper portion) mounted on the base 30. In some embodiments, base 30 may be permanently secured to retainer 32. Thus, retainer 32 may define an upper skin contact surface 14, and blades 24a, 24b, and 24c may be mounted to base 30. In some embodiments (with or without clamps 28a and 28b), retainer 32 may hold blades 24 within base 30. For example, clamps 28 may provide temporary or additional securing measures for blades 24a, 24b, and 24c.

[0018] The base 30 may have a front wall 34 and a rear wall 35, which have corresponding top surfaces 36 and 37. A first cutting blade 26a may be located immediately behind the front wall 34 to facilitate unobstructed passage of hair to the first cutting blade 26a. One or more of the top surfaces 36 and 37 may be recessed relative to the cutting blades 26a, 26b, and 26c. Top surfaces 36 and 37 may extend along a length “L1”. It should be understood that the front wall 34 and rear wall 37 may have one or more protruding features to facilitate securing the base 30 to the retainer 32. Top surfaces 36 and 37 may extend between and be positioned below clamps 28a and 28b. The recessed top surface 36 may allow an opening area in front of the first cutting blade 26a so that hair is not trapped, and provides an area on the housing for resting the clamps 28a and 28b above the top surface 36. For example, one or more of the top surfaces 36 and 37 may be recessed by more than 0.20 mm relative to the first cutting edge 26a, such that the top surfaces 36 and 37 do not interfere with or contact the skin during hair trimming. As will be explained in more detail below, all blades 24a, 24b, and 24c may be mounted to the base 30 such that the cutting edges 26a, 26b, and 26c are positioned above the top surface 36 along a length “L1”. In some embodiments, L1 may be from about 17 mm to about 35 mm. Therefore, all cutting edges 26a, 26b, and 26c are not protected by guards and caps as in a conventional razor blade holder, and because the top surfaces 36 and 37 are recessed so that they do not serve as guards and caps to support (e.g., contact) the skin, all shaving forces will be applied directly to the cutting edges 26a, 26b, and 26c. However, the retainer 32 can be mounted on the base 30 to prevent the cutting blade 26 from contacting the skin, thus resulting in a very safe shaving by cutting the hair to a predetermined length. Clamps 28a and 28b can be mounted to the base 30 before the retainer 32 is mounted to the base 32. The retainer 32 can define a pair of openings 38a and 38b, sized to receive the corresponding clamps 28a and 28b. The retainer 32 can be spaced apart from the clamps 28a and 28b to facilitate simple assembly. For example, openings 38a and 38b can allow clamps 28a and 28b to be secured to the housing 12 before or after the retainer 32 is mounted to the base 30. Openings 38a and 38b can allow the retainer 32 to directly contact the cutting blades 26a, 26b, and 26c without resting on the tops of the clamps 28a and 28b. In some embodiments, the retainer 32 rests directly against the cutting blades 26a, 26b, and 26c, thus potentially eliminating the need for the clamp 28. Furthermore, if the retainer 32 rests on top of the clamp 28 instead of on the cutting blades 26a, 26b, and 26c, hair and shavings can be trapped between the retainer 32 and the cutting blades 26.Openings 38a and 38b can be closed and extend between the front 16 and the back 40. (The same applies.) Figure 1B As shown, the rear 40 may interconnect the ribs 22 at the rear of the housing 12 (e.g., the retainer 32), and the lower surface 21 may interconnect the ribs 22 at the front of the housing 12 (retainer 32) to reinforce the ribs 22.

[0019] refer to Figure 3 The diagram illustrates a subassembly 44 that can be incorporated into the razor blade holder of FIG1. ​​Subassembly 44 may include a base 30, blades 24a, 24b, and 24c, and clamps 28a and 28b. Blades 24a, 24b, and 24c may be mounted to the base 30 between a front wall 34 and a rear wall 46. In some embodiments, the length “L1” of the top surface 36 of the front wall 34 may be at least 90% of the total exposed length “L2” of the blades 24a, 24b, and 24c (e.g., the distance between clamps 28a and 28b). The top surface 36 may be defined on the lateral ends 48 and 50 by retaining walls 52 and 54. Retaining walls 52 and 54 may extend over the top surface 36 to facilitate positioning and securing clamps 28a and 28b to the base 30. For example, each clamp 28a and 28b may be positioned between one of the retaining walls 52 and 54 and the corresponding lateral walls 56 and 58.

[0020] refer to Figure 4 It shows roughly along Figure 3The image shows a cross-sectional view of subassembly 44 taken by line 4-4. A top surface 36 on the front wall 34 of the base 30 may be positioned at a vertical distance of at least 0.5 mm below the cutting blades 26a, 26b, and 26c (e.g., the cutting plane 64). In some embodiments, the vertical distance d1 may be from about 0.5 mm to about 5 mm. The positioning of the top surface 36 allows the hair to reposition itself in a more vertical position as it is cut (e.g., by the first cutting blade 26a). For example, if the top surface 36 is positioned too close to the cutting plane 64 (or the first cutting blade 26a), it may push down in front of the blade 24 and trap long hair, thus negatively impacting cutting efficiency, especially for hair that is longer than hair that tends to lie flat on the skin. One or more of the cutting blades 26a, 26b, and 26c may be positioned at a vertical distance “d2” above a plane P1 tangent to the top surface 36 of the front wall 34 and the top surface 37 of the rear wall 46. The distance d2 may be largest at the first cutting blade 26a closest to the front wall 34 and smallest at the closest to the rear wall 46. It is believed, without being bound by theory, that increasing d2 closer to the front wall 34 improves cutting efficiency. After the hair has been trimmed by the first cutting blade 26a, the hair is less likely to be flattened because it is shorter, therefore d2 may be smaller at the second cutting blade 26b and even smaller at the cutting blade 26c closest to the rear wall 46. In some embodiments, d2 may be from about 0.5 mm to about 3 mm when measured at any of the cutting blades 26a, 26b, and 26c.

[0021] The shaving efficiency of the razor blade holder 10 (Fig. 1) can be enhanced by improving washability. Conventional razor blade holders rely on a smaller distance between the cutting blades or an intermediate guard between adjacent blades to improve comfort, as pressure is distributed between the cutting blades 26a, 26b, and 26c. However, the rib 22 (Fig. 1) absorbs all the pressure from the skin, rather than from the cutting blades 26a, 26b, and 26c, allowing the cutting blades 26a, 26b, and 26c to be spaced further apart. In some embodiments, the distances “d3” and “d4” between a pair of adjacent cutting blades 26a, 26b, and 26c can be greater than 1.75 mm, for example, from about 1.8 mm to about 2.0 mm, or from about 2.0 mm to about 2.5 mm, which allows for an open gap (e.g., between the closest cutting blades 26a, 26b, and 26c) to be provided. Figure 3 (Best of the best view) to perform even more efficient rinsing without sacrificing trimming efficiency or comfort.

[0022] refer to Figure 5Figure 1 shows a cross-sectional view of the razor blade holder 10, taken approximately along line 4-4 of FIG. 1. A retainer 32 may be mounted to a subassembly 44 (i.e., base 30). The housing 12 (e.g., base 30 and retainer 32) allows hair to pass freely through the slot 20 of the front 16 (FIG. 1). The upper skin contact surface 14 and the front 16 may intersect at an external angle “A1” of less than 90 degrees, for example, about 45 degrees to about 85 degrees, to facilitate hair passage through the slot 20 of the front 16 (FIG. 1). The intersection of the front 16 and the upper skin contact surface 14 may form a rib 22 with a radius R1. In some embodiments, R1 may be about 0.1 mm to about 3 mm, and preferably about 0.25 mm to about 1 mm. The lower surface 21 may be positioned at a vertical distance “d5” at least 0.5 mm (e.g., about 0.5 mm to about 3 mm) below the cutting blades 26a, 26b, and 26c. The 40th rib may have rib 22 (see also) Figure 1B The top surface 60 extending between the cutting blades 26a, 26b and 26c is positioned at a vertical distance “d6” below the cutting blades 26a, 26b and 26c, which helps to free the hair (i.e., prevent the hair from being flattened during the shaving stroke), thus allowing for more efficient hair trimming.

[0023] The upper skin contact surface 14 may have an opposing inner surface 62 (e.g., the height of the ribs 22). The length of the hair left after trimming with the razor blade holder 10 can be determined by the vertical distance "d8" measured from the upper skin contact surface 14 to the opposing inner surface 62 (e.g., in the case where the cutting blades 26a, 26b, and 26c are in contact with the opposing inner surface 62). It should be understood that the cutting blades 26a, 26b, and 26c may contact or be spaced apart from the opposing inner surface 62. The vertical distance "d8" may be from about 0.5 mm to about 5 mm, and more preferably from about 1 mm to about 2.5 mm. If d8 is too small, the skin may bulge between the ribs 22 and contact the skin, thus cutting the hair too short. Furthermore, hair longer than 5 mm tends to lie flat and therefore will not be cut in cases where d8 is greater than 5 mm.

[0024] It is believed that, without being bound by theory, increasing the vertical distances d5 and d6 improves the cutting effect by minimizing interference with the hair before it is cut by the first cutting blade 26a (up to d5) and after it is cut by the last cutting blade 26c (up to d6). Therefore, the exposure of the cutting blades 26a, 26b, and 26c can be determined by d8 (e.g., the height of the rib 22), rather than features that push hair downwards against the skin, making them more difficult to trim (such as a guard in front of the blade). For typical razors, this problem does not exist with guards that contact the skin because the cutting blades are in contact with and shaving the skin (i.e., cutting hair at or below the skin level). Therefore, the cutting blades can contact and cut hair that can lie flat, lift them, and cut them. However, cutting hair above the skin level is more difficult because the cutting blades may not be able to reach the flat hair. Therefore, the housing 12 can define a horizontal gap 66 extending from the first cutting blade 26a to the front inner surface 68 opposite to the front face 16. In some embodiments, the horizontal gap 66 may be from about 0.5 mm to about 3.0 mm, and more preferably from about 1 mm to about 2 mm. The gap 66 allows for improved rinsing and allows longer trimmed hairs to be rinsed away through the housing 12. The gap 66 also allows hairs to be released and presented to the first cutting edge 26a in a more vertical position. The front wall 34 and the top surface 36 may be recessed and therefore do not extend into the gap 66. It should be understood that the lateral end walls 52 and 54 ( Figure 3 It is positioned laterally at the bottom surface 36 and therefore does not extend into the gap 66.

[0025] Rib 22 ( Figure 1A and Figure 1B Positioned above the cutting blades 26a, 26b, and 26c, the ribs help prevent skin contact with the cutting blades 26a, 26b, and 26c and eliminate the need for a protective strip in front of the cutting blades 26a, 26b, and 26c to support the skin. For example, the height and spacing of the ribs 22 prevent the skin from protruding between the ribs and contacting the cutting blades 26a, 26b, and 26c. Furthermore, the ribs 22 ( Figure 1A and Figure 1B This also allows the cutting blades 26a, 26b and 26c to be spaced further apart from each other, because the cutting blades 26a, 26b and 26c do not exert pressure on the skin.

[0026] The dimensions and values ​​disclosed herein should not be construed as strictly limited to the precise numerical values ​​cited. Rather, unless otherwise specified, each such dimension is intended to represent the stated value and the range around which it is functionally equivalent. For example, a dimension disclosed as “40 mm” is intended to represent “about 40 mm”. The term “about” should be interpreted herein as within typical manufacturing tolerances.

[0027] Unless expressly excluded or otherwise limited, every reference cited herein, including any cross-references or related patents or patent applications, and any patent application or patent claiming priority to or benefiting from it, is incorporated herein by reference in its entirety. Reference to any reference is not an endorsement of it as prior art to any disclosed or protected art herein, nor is it an endorsement of any such invention, either on its own or in combination with any one or more references. Furthermore, where any meaning or definition of a term in this invention conflicts with any meaning or definition of the same term in referenced documents, the meaning or definition given to that term in this invention shall prevail.

[0028] While specific embodiments of the invention have been illustrated and described by way of example, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications falling within the scope of the invention be covered by the appended claims.

Claims

1. A subassembly (44) for a razor blade holder (10), the subassembly comprising: The base (30) includes a front wall (34) having a top surface (36) and a rear wall (35) having a top surface (37). Multiple blades (24a, 24b, 24c) are mounted to the base (30) between the front wall (34) and the rear wall (35), each blade having a cutting edge (26a, 26b, 26c). A retainer (32) is fastened to the base (30). The retainer (32) has an upper skin contact surface (14) and a front surface (16), which are defined by a plurality of ribs (22) forming a plurality of open slots (18, 20). Wherein, the top surface (36) on the front wall (34) of the base (30) is positioned at a vertical distance of at least 0.5 mm below the cutting blades (26a, 26b, 26c), and the front surface (16) of the retainer (32) is in front of the front wall (34) of the base (30); The upper skin contact surface (14) of the retainer (32) and the front surface (16) intersect at an external angle of 45 to 85 degrees; the cutting edges (26a, 26b, 26c) adjacent to the blade are spaced apart by a distance (d3, d4) greater than 1.75 mm.

2. The sub-component (44) according to claim 1, wherein, One or more of the cutting blades (26a, 26b and 26c) are positioned at a vertical distance (d2) above a plane (P1) tangent to the top surface (36) of the front wall (34) and the top surface (37) of the rear wall (35), wherein the vertical distance (d2) is greatest at the cutting blade (26a) closest to the front wall (34) and smallest at the cutting blade (26c) closest to the rear wall (35).

3. The sub-component (44) according to claim 2, wherein, When measured at any of the cutting edges (26a, 26b, 26c), the vertical distance (d2) is 0.5 mm to 3 mm.

4. The sub-component (44) according to claim 1, wherein, The distance (d3, d4) between adjacent cutting edges is 1.8 mm to 2.0 mm.

5. The sub-component (44) according to any one of claims 1-4, wherein, The top surface (36) on the front wall (34) of the base (30) is positioned at a vertical distance of 0.5 mm to 3 mm below the cutting blades (26a, 26b, 26c).

6. The sub-component (44) according to any one of claims 1-5, wherein, The top surface (36) is defined on the lateral ends (48, 50) by retaining walls (52, 54), and clamps (28a, 28b) are positioned between each retaining wall (52, 54) and the corresponding lateral wall (56, 58) of the base (30) to hold the blade (24a, 24b, 24c).

7. The sub-component (44) according to claim 6, wherein, The length (L1) of the top surface (36) of the front wall (34) is at least 90% of the total exposed length (L2) of the blades (24a, 24b, 24c).

8. The sub-component (44) according to any one of claims 1-7, wherein, The front (16) has a lower surface (21) that interconnects the plurality of ribs (22).

9. The sub-component (44) as claimed in claim 8, wherein, The lower surface (21) is positioned at a vertical distance (d5) of 0.5 mm to 3 mm below the cutting blades (26a, 26b, 26c).

10. The sub-component (44) according to claim 8 or 9, wherein, The retainer (32) has a rear end (40) with a top surface (60) extending between the ribs (22), the top surface of the rear end being positioned at a vertical distance (d6) below the cutting blades (26a, 26b, 26c).

11. The sub-component (44) according to any one of claims 1-10, wherein, The width (w1) of the rib (22) is 0.25 mm to 5 mm, preferably 0.4 mm to 1 mm.

12. The sub-component (44) according to claim 11, wherein, The ribs (22) are spaced apart to define the opening slots (18, 20), the width of which is from 0.25 mm to 5.0 mm, preferably from 0.7 mm to 0.8 mm.

13. The sub-component (44) according to claim 12, wherein, The width (w1) of the rib (22) is less than the distance between the ribs (22).

14. The sub-component (44) according to any one of claims 1-13, wherein, The base (30) and the retainer (32) define a horizontal gap (66) extending from the first cutting edge (26a) of the blade (24a) closest to the front wall (34) to the front inner surface (68) of the retainer (32) opposite to the front face (16), wherein the length of the horizontal gap (66) is 0.5 mm to 3.0 mm.

15. The sub-component (44) according to any one of claims 1-14, wherein, The intersection of the front (16) and the upper skin contact surface (14) forms the radius (R1) of the rib (22), the value of which is 0.1 mm to 3 mm.

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