Patent Application
20220088813
The following description relates to bent blades, particularly to razor cartridges comprising such bent blades.
Shaving devices generally include a head unit having at least one or more cutting members or blades retained therein. The at least one or more cutting members or blades have cutting edges that are aligned in parallel when retained within the head unit.
Some known shaving devices incorporate bent blades as cutting members. In comparison to blades welded on blade supports, bent blades increase rinsability, are more cost-efficient to produce (less material used, less process steps) and their shaving performance is quite comparable.
However, since bent blades use less material (less volume and cross-sectional area) compared e.g. to typical blades welded on a blade support, bent blades tend to elastically deflect more than the blades welded on a blade support when subject to the same shaving force.
To address the deflection issues with bent blades, prior cartridge designs for bent blades are provided with additional protrusions receiving the bent blade near or at the middle region of the blades, thus providing additional support and minimizing blade deflection. In circumstances, a bent blade may have a tendency to deflect towards the back of the razor (i.e. across x-direction parallel to the shaving plane) and at the same time the edge may be displaced or deflected towards the skin area (i.e. across y-direction that is vertical to the shaving plane). These deflections may result in poor shaving performance, e.g. less closeness, less hair pull out force and/or less nicks and cuts and irritation. This may result in an increased wear of the blade edge.
Nevertheless, although these extra supports minimized the x-direction deflection, the y-direction deflection, although it was also decreased, was not as rigid as the blades welded on a blade support.
It is therefore desirable to decrease the y-direction deflection of a bent blade and to decrease overall blade deflection during shaving.
The present disclosure provides a razor blade extending along a longitudinal axis. The blade comprises a cutting edge portion positioned along a second plane, a base portion positioned along a first plane that is different from the second plane, the first plane intersects the second plane at an angle. The razor blade further comprises a bent portion intermediate to the cutting edge portion and base portion, and an extended portion extending from the base portion away from the second plane. The cutting edge portion, base portion, bent portion, and extended portion are monolithically formed.
The extended portion may have a length along the longitudinal axis that is between 0.035 and 0.9 of a length of the razor blade along the longitudinal axis.
The extended portion may have a length along the longitudinal axis that may be between 0.05 and 0.2 the length of the razor blade along the longitudinal axis.
The extended portions may have an approximate length along the longitudinal axis of 12 mm.
The extended portion may extend away from the base portion a distance that is within a range of 0.5 mm to 7 mm, specifically of 1 mm to 7 mm, more specifically of 1 mm to 3 mm, even more specifically of 1.2 mm to 3 mm and even more specifically about 1.6 mm.
A total height of the base portion and the extended portion may be within a range of 1.0 mm to 12 mm, specifically of 2 mm to 12 mm, more specifically of 2 mm to 5 mm and even more specifically about 3 mm.
The extended portion may be centered along the length of the razor blade along the longitudinal axis.
The razor blade may comprise two extended portions.
Each of the extended portions may be offset from the center of the length of the razor blade along the longitudinal axis.
At least one of the extended portions may have an approximate length along the longitudinal axis of 1.4 mm.
The extended portion may be positioned along the first plane.
The extended portion may include a shaped portion. In some examples, the shaped portion may be positioned along a third plane that is different from the second plane.
A method of manufacturing a razor blade comprises: providing a strip having a cutting edge portion, a base portion, a bent portion intermediate to the cutting edge portion and base portion, an extended portion, and a removable portion. Perforations are provided along the length of the strip positioned within the removable portion and adjacent to the extended portion and to the base portion. The method further includes separating the removable portion from the base portion and the extended portion by cutting the strip at a point where the removable portion starts.
The method may further comprise forming the extended portion to include a shaped portion. I some examples, the shaped portion may be formed by stamping. In others it may be formed by bending the shaped portion along a plane that is different from a plane along which the extended portion extends. In examples, the shaped portion may be formed by stamping and bending.
The proposed disclosure provides bent blade designs that comprise one or more blade body extensions provided at the back portion, the extended portion. These extensions provide extra blade material that increases the cross-sectional area of the blade thereby acting against deflection. In some examples, the extensions increase the cross-sectional area at (or close to) the central region of the blade, which in circumstances may be the portion of the blade that may be the most sensitive to deflection. The proposed disclosure provides for bent blades that are more rigid and better able to withstand the hair cutting forces during shaving. The blade edge of these improved blades deflects less than the ones disclosed in the prior art, especially in the y-direction. This decreased deflection results in a more efficient shaving because the blades can penetrate the hairs more easily, thus reducing the cutting forces and minimizing a hair-pulling effect. It also provides a more comfortable shaving experience. Further, skin safety is also enhanced, by minimizing skin irritation, nicks, and cuts. In addition, the cartridge housing does not need any further cumbersome component to be provided in order to further reduce blade deflection.
When making a bent blade 10 from the blade strip 1, the bendable portion 3 of the blade strip 1 is bent such that the cutting edge portion 12 is positioned along a second plane that intersects the first plane and the base portion 14 is positioned along the first plane. Subsequently, the removable portion 16 is cut away from or broken off of the base portion 14 via the perforations 16a.
When making the bent blade 100 from the blade strip 1, the bendable portion 3 of the blade strip 1 is bent such that the cutting edge portion 12 is positioned along a second plane that intersects the first plane and base portion 14 is positioned along the first plane. Subsequently, the removable portion 60 is cut away from or broken off of the base portion 14 via the perforations 60a such that the extended portion 50 remains attached to the base portion 14.
A total height H1, which is the distance measured in the y-direction between an exposed end of the extended portion 150 and the end of the base portion 14 that connects with the bent portion 13, may be in a range of 1.0 to 12 mm, specifically of 2 mm to 12 mm, more specifically of 2 mm to 5 mm and even more specifically about 3 mm. A height EH1, which is a distance measured in the y-direction between the exposed end of the extended portion 150 and the end of the extended portion 150 that connects with the base portion 14, may be in a range of 0.5 to 7 mm, specifically of 1 mm to 7 mm, more specifically of 1 mm to 3 mm, even more specifically of 1.2 mm to 3 mm and even more specifically about 1.6 mm. The length EL1 of the extended portion 150 is a distance measured in the z-direction between exposed side ends of the extended portion 150 and measured orthogonal to the height EH1 of the extended portion 150. The ratio EL1/L may be between 0.035 to 0,9, specifically 0.05 to 0,2, more specifically about 0,07, wherein L is a total length of the blade measured in the z-direction.
It is also envisioned that a bent blade 200 may have two extended portions 250, which is shown in
A total height H2, which is the distance measured in the y-direction between an exposed end of one of the extended portions 250 and the end of the base portion 14 that connects with the bent portion 13, may be in a range of 1.0 to 12 mm, specifically of 2 mm to 12 mm, more specifically of 2 mm to 5 mm and even more specifically about 3 mm. A height EH2, which is a distance measured in the y-direction between the exposed end of one of the extended portions 250 and the end of the extended portion 250 that connects with the base portion 14, may be in a range of 0.5 to 7 mm, specifically of 1 mm to 7 mm, more specifically of 1 mm to 3 mm, even more specifically of 1.2 mm to 3 mm and even more specifically about 1.6 mm. The length EL2 of one of the extended portions 250 is a distance measured in the z-direction between exposed side ends of one of the extended portions 250 and measured orthogonal to the height EH2 of the extended portion 250. The ratio EL2/L being between 0.035 to 0,9, specifically 0.05 to 0,2, more specifically about 0,07, wherein L is a total length of the blade measured in the z-direction.
A total height H3, which is the distance measured in the y-direction between an exposed end of the extended portion 350 and the end of the base portion 14 that connects with the bent portion 13, may be in a range of 1.0 to 12 mm, specifically of 2 mm to 12 mm, more specifically of 2 mm to 5 mm and even more specifically about 3 mm. A height EH3, which is a distance measured in the y-direction between the exposed end of the shaped portion 352 and the end of the extended portion 350 that connects with the base portion 14, may be in a range of 0.5 to 7 mm, specifically of 1 mm to 7 mm, more specifically of 1 mm to 3 mm, even more specifically of 1.2 mm to 3 mm and even more specifically about 1.6 mm. The length EL3 of the extended portion 350 is a distance measured in the z-direction between exposed ends of the extended portion 350 and measured orthogonal to the height EH3 of the extended portion 350. The ratio EL3/L being between 0.035 to 0,9, specifically 0.05 to 0,2, more specifically about 0,07, wherein Lisa total length of the blade measured in the z-direction.
The blade strip 40 further includes a removable portion 460. The removable portion 460 includes a plurality of perforations or weakening holes 460a. The blade strip 40 may be composed of stainless steel, which has previously been subjected to a metallurgical treatment. For instance, the blade strip 1 comprises mainly iron and, in weight: C: 0.48-0.72%; Si: 0.15-0.60%; Mn: 0.20-0.90%; Cr: 12.0-14.7%; and Mo:1.20-1.40%. It is foreseen that other stainless steels may be used without deviating from the scope of the present disclosure. For instance, other materials commonly used for razor blade substrate materials may be used. The cutting edge portion 412, bendable portion 43, base portion 414, and removable portion 460 may be monolithically formed. The blade strip 40 includes an extended portion 450 that is positioned along the first plane and extends from the center of the length of the base portion 414 and is not included in the removable portion 460. Thus, the extended portion 450 will not be removed during forming. The cutting edge portion 412, bendable portion 43, base portion 414, and extended portion 450 may be monolithically formed. The extended portion 450 may extend from the center of the length of the blade 400 to minimize deflection in the area that is most sensitive to deflection during a shaving operation.
When making the bent blade 400 from the blade strip 40, the bendable portion 43 of the blade strip 40 is bent such that the cutting edge portion 412 is positioned along a second plane adapted to intersect the first plane and the base portion 414 remain positioned along the first plane. Subsequently, the removable portion 460 is cut away from or broken off of the base portion 414 via the perforations 460a.
In some examples, the increased rigidity may allow for the use of blade strips having a reduced thickness, thereby reducing the amount of material involved. Typical blade strip thickness may range from 0.15-0.1 mm. Blades with increased rigidity may allow for blade strip thickness to be below 0.1 mm. In examples, blade thickness may be between 0.08-0.05 mm. Particularly 0.074 mm.
In examples wherein the extended portion includes a shaped portion, the shaped portion may comprise an inclined surface, or a curved surface, which may be formed by bending or by stamping process. In some of these cases, a curved surface in the same plane as the extended portion may be provided. I some cases, an inclined surface along a plane that is different from that of the extended portion may be provided. Combinations of these shaped portions may be provided in some examples.
| Number | Date | Country | Kind |
|---|---|---|---|
| 19160012.1 | Feb 2019 | EP | regional |
This application is a National Stage Application of the International Application No. PCT/EP2020/055321, filed on 28 Feb. 2020, now published as WO/2020/174091, and which claims priority to European Patent application EP 19160012.1 filed on 28 Feb. 2019, entitled “BENT BLADE WITH IMPROVED RIGIDITY”, the entire contents of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/055321 | 2/28/2020 | WO | 00 |
