JP2004511319A - Safety razor - Google Patents

Abstract

The safety razor blade unit (2) comprises a blade assembly (5) having a plurality of parallel blades (16) mounted on a razor handle (1) by a flexible support structure (4). I have. Each blade (16) has a leading edge portion (50) with a sharp cutting edge (17) and an elongated blade with a flat blade portion (54) extending rearward from the leading edge portion (50). Element. The leading edge portion is a blade element material between the press machines in a transition region extending no more than 1 mm rearward from the tip of the cutting edge (17) between the leading edge portion (50) and the flat blade portion (54). Can be tilted upward by bending. The lower surface is convex and the upper surface is concave. The plane bisecting the tip (Pt) forms an angle of 10 to 35 degrees with respect to the central plane (Pm) of the flat part (54). The blade (16) is arranged in the blade unit (2) such that the tangent plane contacting the surfaces of the guard (26) and the cap (24) of the blade unit and the central plane (Pm) of the flat part are parallel. Is done. The tip of the cutting blade is above the plane (Pn) of the upper surface of the flat part at a height of 0.05 to 0.15 mm. To ensure good flexibility, the blade cross section is 1.0 × 10 ⁻⁴ mm ⁴ It has the following minimum second moment of area.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a safety razor of the type comprising at least one blade having a sharp cutting edge, wherein the blade unit assembly is carried by the handle and moved by the handle across the surface of the razor skin. The blade unit is removably mounted on the razor handle so that it can be replaced with a new one when the blade sharpness is reduced to an unsatisfactory level, or the entire razor is intended to be thrown away when the blade becomes dull Is fixedly attached to the handle below. A removable and replaceable blade unit is commonly called a razor cartridge. The present invention relates in particular to a blade of a safety razor blade unit, and more particularly to an elongated blade having a cutting edge extending along the blade.
[0002]
The safety razor blade unit generally includes, in addition to at least one blade, a guard that defines a surface that contacts the skin in front of the blade as the blade unit moves across the skin during a razor stroke, and a blade. A so-called cap for defining a skin contacting surface behind the cap. For best performance, each blade must be oriented so that it is inclined with respect to the cap and guard surfaces relative to the plane tangent to those surfaces ("tangent plane"). It is well known that it must not. Tilting the blade causes the midplane of the plate of the blade, the plane bisecting the angle defined between the edge facets forming the cutting edge at the tip of the blade, to the tangent plane. It sometimes means making an angle called "blade tangent angle".
[0003]
The blade can be fixed in place so that the tangent angle of the blade does not change significantly when using a razor. Alternatively, it is also well known to mount the blades so that they can move within the frame to change the tangent angles of the blades as a result of the movement of the blades during the action of a razor stroke. In any event, a substantially flat blade element having a cutting edge and a blade portion extending at least a few millimeters rearward from the faceted edge will be at an appropriate angle to the tangent plane. Thus, it is conventional practice to support each blade on a safety razor blade unit. In one well-known construction, a curve having a forward and upwardly inclined portion on which the blade element is carried, and an upright rear portion slidably guided within a frame on which the blade is mounted. A flat blade element is mounted on the resulting blade support.
[0004]
The need to set the blade tangent angle by accurate positioning of the blade during assembly of the blade unit is inconvenient and tends to complicate not only the procedure of assembling them, but also the structure of the blade unit. is there. Furthermore, modern safety razors generally have two to three blades with edges parallel to each other, and a plurality of such blades for each plane inclined with respect to the tangent plane. Has the possibility of impairing the flexibility (adaptability) that the blade unit should have.
[0005]
A safety razor has been proposed with a blade element having a circular cutting edge extending around the hole. Examples of such safety razors are described in US-A-5,201,253 and US-A-5,490,329. Unlike blades with straight cutting edges, blade elements with circular cutting edges can be tilted at the desired angle with respect to the sharpened edge during the razor and in the desired position with respect to the skin. Can not. Therefore, these blade elements need to be manufactured by special grinding techniques, e.g. as taught by US 5,490,329, to ensure the required shape and inclination of the edges. Alternatively, as described in US-A-5,201,253, the edge can be deformed after sharpening to give the circular edge the required shape. These proposals have been made in order to solve the problems inherent in blade elements, in particular with circular cutting edges, and have obviously not been applied to blades having straight edges without similar difficulties.
[0006]
U.S. Pat. No. 5,010,646 describes a blade unit for a safety razor, in which the blade incorporated has a sharp part with a sharp edge extending along itself. Or it is curved so as to form an angle of about 112 degrees with the guide portion. The two parts are corrugated for the purpose of removing stress. A blade that is curved in this way not only greatly reduces flexibility but also does not provide any solution to the above-mentioned disadvantages of flat blades, which are heretofore well known.
[0007]
US-A-3,938,250 describes a composite blade assembly for a safety razor, the composite blade assembly comprising a flat blade and an auxiliary blade fixed to the lower surface of the flat blade. And a member. The auxiliary blade member is curved to increase the span between the flat blade and the cutting blade provided on the auxiliary blade member. Also, the tangent angle of the blade of the auxiliary blade member is reduced by the curved blade member. This curved blade member is particularly adapted for the manufacture of multiple tandem blades and requires that the blade be set at an angle to provide the desired blade tangent angle. . For this reason, it does not provide any obvious solution to the disadvantages of known structures that limit flexibility.
[0008]
With this form of blade, a relatively small tip can be bent to achieve the desired blade tangent angle while leaving the majority of the blade substantially flat and parallel to the tangent plane, thereby providing a particularly diverse blade. Flexibility in the blade unit having the blade can be enhanced.
[0009]
The present invention must, for that purpose, remove, or at least substantially relax, the limitations of the prior art blade structures. The invention particularly relates to a blade of a safety razor blade unit, comprising an elongated blade element having an upper surface and a lower surface, a sharp cutting edge extending along itself and a surface tapering towards the tip of said cutting blade. A leading edge portion defined by a portion, and a substantially flat blade portion extending rearward from the edge portion and having the upper and lower surfaces parallel thereto. The lower surface has a convex curvature in a transition region between the edge portion and the upper surface is directed to a non-convex, preferably concave, blade.
[0010]
According to one aspect of the invention, the blade has a cross section of 1.0 × 10 along at least a majority of its length.^-4mm⁴A blade of the above-described configuration is provided having the following minimum moment of inertia:
[0011]
The moment of inertia of the cross-sectional shape of the blade depends on the size and shape of the cross-section and is also a measure of the flexibility of the blade. Although the flexibility depends on the Young's modulus of the blade material, the second moment of area is a good indicator of the blade's flexibility because the razor blade materials currently in use have Young's modulus close to each other. It is. Although the area moment of inertia is measured about one axis, the smallest area moment of inertia means that the area moment of inertia is measured about an axis that results in the lowest value for the blade section. Minimum moment of inertia of area is 0.5 × 10^-4mm⁴The blade is preferably 0.35 × 10^-4mm⁴Less than 0.20 × 10^-4mm⁴Less than, for example, 0.14 × 10^-4mm⁴It may have a minimum moment of inertia of cross-section of before, after, or less.
[0012]
According to another aspect, the present invention provides a method, wherein the plane bisecting the tip of the blade edge is inclined at an angle in the range of 10 to 35 degrees with respect to the mid-plane of the flat blade section. A blade having the form defined in (1). By setting the leading edge portion at such an inclination, an effective blade tangent angle to a flat blade portion that is substantially parallel to the tangent plane can be assured. The angle between the tip bisector and the mid-plane of the flat blade section is preferably in the range 15-30 degrees, especially 20-25 degrees.
[0013]
A blade according to yet another aspect of the present invention has a leading edge portion extending rearward from the tip of the cutting blade by a distance of 1 mm, preferably 0.5 mm or less.
[0014]
According to a preferred embodiment, the leading edge portion is separated by a distance that does not substantially exceed the tapering surface portion, more specifically such that the length of the flat portion extending rearward from the front portion is several times that distance. Only, extending backward from the tip.
[0015]
According to the different aspects of the invention described above, the blade element conveniently comprises a metal strip having a bend at the junction of the leading edge portion and the flat blade portion.
[0016]
According to yet another aspect, a safety razor blade unit of the present invention includes a guard surface, a cap surface, an elongated blade element having an upper surface and a lower surface, a sharp cutting edge extending along itself, and the cutting edge of the cutting blade. A leading edge portion defined by a surface portion that tapers toward a tip, at least having a substantially flat blade portion extending rearward from the leading edge and having the upper and lower surfaces parallel thereto. A lower blade has a convex curvature and the upper surface is concave in a transition region between a flat blade portion and a leading edge portion, thereby forming a tip of the blade. The plane bisecting the tangent to the mid-plane of the flat blade portion, with respect to the tangent plane tangent to the surface of the guard and the cap It forms an angle greater than the angle relative to the plane.
[0017]
The center plane of each blade is preferably substantially parallel to a tangent plane that contacts the cap surface and the guard surface. Due to the concave upper blade surface in the transition region, the tip of the cutting blade is above the plane of the upper surface of the flat blade portion. Preferred blade elements have a cutting edge at a height of up to 0.25 mm above the plane of the upper surface, in particular in the range of 0.15 mm to 0.05 mm.
[0018]
According to the blade provided by the present invention, the tangent angle of the blade can be effectively set while manufacturing the blade itself. Furthermore, because most of each blade is flat, two or more blades can be arranged in an essentially flat array, with blades having much greater flexibility than previously achievable. Aggregates can be produced. The advantages of the present invention are most pronounced when the upwardly sloping blade portion at the leading edge portion is limited to a small area near the cutting edge.
[0019]
The plurality of blades according to the present invention as described above are interconnected such that their cutting edges are substantially parallel, and the flat portions of the blades are substantially coplanar, thus ensuring safety. When the razor blade unit is manufactured, the razor blade unit can be conveniently assembled together with other parts into a blade assembly constituting an assembling subunit. The blades can be conveniently interconnected by transverse strips attached to the underside of the flat portion of the blade. These interconnect strips can also serve to secure the blade assembly to the blade unit support structure.
[0020]
In a razor blade unit incorporating a blade of the present invention, the flat portion of the blade is coplanar or parallel to a tangent plane tangent to a cap surface and a guard surface defined by the blade unit. It is advantageous to be on a flat plane. Such an arrangement maximizes the benefits obtained from the blade flexibility that the present invention can make use of.
[0021]
The blade of the invention may consist of a blade element with a strip of metal, for example steel, having a bend at the junction of the leading edge and the flat part. The material of the blade can be conventional and the cutting edge can be provided with a known coating, including a hard coating such as boron nitride, amorphous diamond, or diamond-like carbon. These coatings can be applied one or more coatings after bending the blade element, but are preferably deposited near the tip before bending the blade element.
[0022]
According to yet another aspect of the present invention there is provided a method of manufacturing a blade according to the present invention as described above. This manufacturing method
Providing a substantially flat elongated blade element material having a sharp cutting edge extending along itself and defined by a surface portion tapering toward the tip of the cutting edge;
-Bending the blade element material in a region no more than 1 mm behind the tip of the cutting blade so that the tip of the cutting blade is spaced from the initial plane of the material;
Is provided.
[0023]
During the bending operation, the tip of the cutting edge is preferably displaced above the upper surface plane of the blank, for example at a height of at most 0.25 mm, such as 0.05 to 0.15 mm above this plane. .
[0024]
In addition, the invention comprises a machine for producing a blade according to the invention. The machine includes a first member having a flat surface extending forward by an inclined surface, and a second member having a flat surface which is capable of coming and going while being opposed to the flat surface of the first member. And the members are guided toward and away from each other to press the blade element blank between them.
[0025]
A rear stop may be provided to abut the trailing edge of the blade element blank to suppress unnecessary movement of the blade element blank during pressing and / or The sloped surface can also be limited by a front stop arranged to engage the leading edge of the blank.
[0026]
The blades of the present invention are similar to the blade units as described and claimed in our currently pending UK patent application 0025336.9 and the international patent application claiming priority therefrom. It is also particularly advantageous when used in a safety razor blade unit having an elastically compliant blade support structure. The contents of these applications are included in the disclosure of the present application by this reference.
[0027]
A clear understanding of the present invention may be had from the following detailed description, which proceeds with reference to the accompanying drawings.
[0028]
The razor illustrated and described below in FIGS. 1-11 is also described and claimed in the aforementioned British Patent Application No. 0025336.9, and claims priority of an international application therefrom. This razor has a handle 1 mounted on a blade unit 2. As shown, the handle 1 has a fixed support platform 3 to which the blade unit 2 is securely fixed, but attaches the blade unit 2 to the handle 1 so that the blade unit 2 can be replaced. It can also be detachably connected.
[0029]
The blade unit 2 has a support structure 4 for supporting the blade assembly 5. The support structure 4 is integrally formed of rubber or a material having elastic and flexible properties similar to rubber, and has an upper frame 6 on which a blade assembly 5 is disposed, and a substantially flat plate. It has a sub-frame 7 in the shape of a trough, and a base 8 also in the form of a substantially flat plate.
[0030]
The upper frame 6 and the sub-frame 7 are connected by an integral hinge 9 at the front edge thereof, and are usually arranged so as to move away from the hinge 9 rearward and away from each other. Similarly, the sub-frame 7 and the base 8 are connected at the trailing edge by an integral hinge 10 and are usually arranged so as to move away from the hinge 10 as they move forward. With such a structure, the upper frame 6, the sub-frame 7, and the base 8 define a Z-shape as shown in the end view (FIG. 3) or the cross-sectional view (FIG. 4). However, the angle between the upper frame 6 and the sub-frame 7 is such that the upper frame 6 is at an appropriate angle to the stem of the handle 1 and ensures the desired deformation characteristics of the support structure described below. α is larger than the angle β between the subframe 7 and the base 8.
[0031]
Extending between and integrally connected to the upper frame 6 and the subframe 7 are a number of flexible webs 12 uniformly and spaced along the support structure. is there. Although six webs 12 are shown, the number can be more or less. These webs 12 are typically in respective planes perpendicular to the upper frame 6 and the sub-frame 7. The flexible webs 12 each constitute a spring element and can be respectively curved and deformed such that each part of the upper frame 6 in the area of the web can be displaced towards the sub-frame 6, The curved web 12 exerts a constant restoring force irrespective of the degree of its curvature, and thus the degree of displacement of the upper frame 6. Since these webs 12 work independently of each other, different portions along the length of the upper frame 6 can be easily displaced by different amounts to the sub-frame 7 side.
[0032]
The subframe 7 is likewise supported on the base 8 by a series of six integral webs 14 arranged evenly spaced along the blade unit. Conveniently, web 14 is aligned with and coplanar with web 12. The buckleable web 14 serves as an independent spring element acting between the subframe 7 and the base 8 and localizes the subframe 7 to the base 8 and thus to the handle 1 While providing a substantially constant restoring force against such displacement.
[0033]
The elastic and flexible nature of the support structure 4 by the webs 12, 14 conforms to the contours of the skin without inevitably affecting the placement of the other parts, so that the upper frame 6 and the blade assembly 5 The upper frame 6 and certain parts of the blade assembly 5 mounted thereon can flex toward the razor handle 1 such that the upper frame 6 can be curved according to the undulations of the skin area moving thereon. It is something like Thus, the blade unit is elastically compliant and ensures intimate contact with the skin throughout the area covered by the blade.
[0034]
Here, FIGS. 8 and 9 show a state in which the blade unit 2 having the upper frame 6 and the blade assembly 5 is deformed in a concave shape, and the intermediate portion M thereof is larger than both end portions E. Buckling deformation. At this time, the webs 12 and 14 near the center M of the blade unit 2 are displaced toward the handle 1 to a greater extent than the webs 12 and 14 arranged near both end portions E of the blade unit 2. On the other hand, FIGS. 10 and 11 show the blade unit 2 deformed in a convex shape, but the blade assembly 5 and the upper frame 6 are arranged at both end portions E of the blade unit from the central portion M of the blade unit. Also buckle down toward the handle 1. In this case, the webs 12 and 14 near the end portions E of the blade unit 2 are more greatly deformed than the webs 12 and 14 closer to the center M of the blade unit 2.
[0035]
8-11, both sets of spring webs 12, 14 are buckled together, but this is not unavoidable or essential. For example, the web 14 does not buckle and the upper frame 6 and the blade assembly do not deform at all at the front end F as a result of the downward razor force being applied to the rear end R of the blade unit. In addition, the web 12 can be buckled so that the upper frame 6 and the blade assembly 5 are displaced downward near the rear end R. The force applied near the leading edge also causes the web 14 to buckle without the web 12 buckling, thereby displacing the upper frame 6 and blade assembly downward at the leading edge F. Can be As a result, the upper frame 6 and the blade assembly 5 are flexible both in the longitudinal direction of the blade unit and in a direction perpendicular thereto so as to closely follow the contour of the skin area to be razed.
[0036]
Since the angle α between the upper frame 6 and the sub-frame 7 is greater than the angle β between the sub-frame 7 and the base 8, the web 12 is somewhat longer than the web 14 and accordingly weaker than the web 14. . Thereby, the web 14 is more resistant to the downward displacement of the upper frame 6 and the blade assembly 5 than the downward displacement exerted by the web 12 at the trailing edge R of the upper frame 6 and the blade assembly 5. Also exert a great resistance at their leading edges F. Such a feature is considered to be preferred because a force greater than the force applied to the cap area during the razor is applied to the blade unit in the guard area.
[0037]
The blade assembly 5 includes a guard member 15 and a plurality of elongated blades 16, which are formed from a flexible metal strip, the blades 16 being parallel and forward facing each other. It has a sharp edge (cutting edge) 17. Guard member 15 and blade 16 are interconnected by a transverse strip 18 attached to the underside of blade and guard member 15. Maximum flexibility of the blade unit is ensured by the coplanar blade 16 and the transverse connecting strip 18 in the normal, undeformed state of the blade assembly 5 and the blade unit 2. Guard member 15 is also substantially coplanar with blade 16 and connecting strip 18, as shown in FIGS. However, the guard member 15 has a rear portion that is inclined upward, and slits 19 that are spaced along this portion of the guard member 15 enhance the flexibility of the member. The fact that the blade assembly has a guard member 15 is advantageous in ensuring the shaving geometry of the blade, in particular of the first blade.
[0038]
The strip 18 has a downwardly folded T-shaped end which engages notches 20, 21 formed in the front and rear edges of the upper frame 6 for securing the blade assembly 5 to the support structure. have. The upper frame 6 has front and rear longitudinal frame members 22 and a transversely extending frame member 23 to which the upper edge of the web 12 is attached. In the assembled blade unit 2, the strip 18 of the blade assembly 5 extends on each frame member 23.
[0039]
The cap 24 of the blade unit 2 has a flexible lubrication strip 25. This lubricating strip 25 sits in a groove extending along the rear longitudinal member 22 of the upper frame 6 and is held in place by the transverse strip 18 of the blade assembly. The support structure 4 forms a guard 26 on the front side of the upper frame 6 in a region hinged to the sub-frame 7. The guard 26 has a plurality of longitudinally extending ribs 27 molded thereon, but may have protrusions of other shapes. Also, preferably, a separate flexible guard element can be mounted on the support structure to provide the desired guard structure.
[0040]
In accordance with the present invention, each blade 16 has an elongated blade element with a leading edge portion 50 (FIG. 12) forming a sharp cutting edge 17 and a substantially flat surface extending rearward from leading edge portion 50. And a blade portion 54. The tip of the cutting blade is defined between opposing surface portions 51, 52, referred to below as a facet that tapers toward the tip. The leading edge portion 50 is such that the plane Pt bisecting the angle between the facets 51, 52 at the tip of the cutting edge is inclined at an angle α of about 20 to 25 degrees with respect to the plane Pm of the flat portion 54. , Is inclined upward toward the tip of the cutting blade 17. The tip of the cutting edge 17 can be located at a height of up to 0.25 mm, preferably in the range of 0.05 to 0.15 mm, above the plane Pu of the upper surface of the flat part.
[0041]
The tilting of the tilted front part 50 causes the flat blade element (the blank 60 as shown in FIGS. 13A, 14A and 15A) to move the lower first member 61 and the upper second member 62. By pressing and bending in a tool assembly consisting of The lower tool member 61 defines a flat press surface 64 extended forward by an inclined surface 65. The upper tool member 62 has a flat press surface 66 opposite the flat press surface 64 of the lower member 61 and the lower member 61 for pressing the blade element blank 60 between the flat press surfaces. It is movable with respect to. The lower member 61 has a rear stopper 67 that contacts the rear edge of the blade element material 60 and a front stopper 68 that is disposed on the inclined surface 65 and contacts the tip of the blade edge (cutting edge). I have. The stops 67, 68 can be adjustable to match the width of the blade element blank 60 to be pressed. Also, in order to adjust the position of the bend to be produced relative to the tip of the blade edge 17, the rear stop 67 is vertically adjustable and has an inclined front surface for this purpose. .
[0042]
An elongated, flat blade element blank 60 having a completed cutting edge 17 along its leading edge is introduced between the upper and lower tool members 61, 62, the trailing edge of which contacts the rear stop 67 and the cutting edge 17 The lower member is brought into contact with the flat surface 64 of the lower member such that the tip comes into contact with the inclined surface 65 and the front stopper 68 (FIGS. 13A and 13B). Thus, the material is initially inclined at a slight angle with respect to the flat surface 64. The upper member 62 is then driven down such that its pressing surface 66 contacts the blank 60, pressing the portion of the blank 60 between the surfaces 61 and 66 against the surface 64, thus removing the leading edge portion 50 of the blade. Pull down against the sloped surface (FIGS. 14A and 14B). In one embodiment, the blade edge facets 51, 52 extend posteriorly from the edge tip by 0.3 mm, the blade thickness is 0.08 mm, and the leading edge of the upper tool is from the tip. It is aligned to be in contact with the blade at a position of 0.4 mm.
[0043]
When the upper member 62 is lifted again, the bending of the blade material 60 caused by the pressing operation is slightly restored. However, the blade blank 60 remains permanently deformed such that the leading edge portion 50 tilts at the desired slope with respect to the flat blade portion 54 extending rearward therefrom. Also, in the transition region between the front portion and the flat portion, the lower surface has a convex curvature while the upper surface is non-convex, especially concave. After the described blade forming operation is completed, a portion of the material, including the sloping leading edge portion and a flat portion that is several times wider than the sloping leading edge portion in the front-to-back direction, is then reduced to the desired width It can be cut or cut from the material to provide a flexible blade strip 16. The blade thus produced is used to produce a blade assembly such as that incorporated into the safety razor of FIGS.
[0044]
The blade 16 of the present invention, manufactured as described above, has its tip raised and the cutting edge 17 lifted to obtain an effective blade contact angle with the flat portion 54 of the blade positioned parallel to the tangent plane. Despite being bent to tilt, it is characterized by relatively high flexibility. This flexibility can be conveniently described by the second moment of area of the blade cross-section, since currently used razor blade materials have Young's moduli that are almost identical to each other. The second moment of area I of the cross-sectional area with respect to the axis X on the cross-section is the sum of the products of each area element dA and the square of the distance y from the axis X. Therefore:
I = ∫y²dA
It goes without saying that the second moment of area depends on the shape and size of the cross section.
[0045]
The smallest moment of area is the second moment of area, as depicted in FIGS. 16A and 16B, which are sections taken in a plane perpendicular to the length of the cutting edge of the two blades 16 according to the invention. Minimum value I of_minIs the second moment of area measured about the axis X resulting in 16A has a thickness of 0.08 mm and a width of 0.80 mm, and the flat portion 54 has a width of 0.40 mm. And its minimum area moment of inertia I about axis X_minIs 0.322 × 10^-4mm⁴It is. The blade of FIG. 16B has a thickness of 0.08 mm and a width of 0.80 mm, and the flat portion 54 has a width of 0.10 mm. In this case, the minimum moment of inertia of area I_minIs 0.145 × 10^-4mm⁴It is.
[0046]
As mentioned above, the blades 16 of the present invention preferably have a blade unit 2 such that the mid-plane of their flat portions 54 is substantially parallel to the tangent planes tangent to the guard surface 26 and cap surface 24 of the blade unit. Is located within. Also, the second moment of area I, measured about an axis that is parallel to these mid-planes and bisects across the area center of the blade shown in FIGS. 16A and 16B, is 0.443 × 10^-4mm⁴And 0.263 × 10^-4mm⁴Has the value of In order to achieve the desired level of blade flexibility in the assembled blade unit 2, a second moment of area about an axis passing through the area center and parallel to the mid-plane of the flat portion 54 is 1.0 × 10^-4mm⁴, Especially 0.5 × 10^-4 mm⁴Not exceed.
[0047]
If the blade 16 has a constant cross-section along its length, the value of I described above applies to any position along its length. However, because of the different cross-sections, there may be shorter blade cross-sections with different values of I. The desired flexibility is also ensured by the blade having a shape such that the specified value of I applies at least along most of the length of the blade.
[0048]
Although the present invention has been described for the formation of a blade having an edge facet that is symmetrical about the center plane of the blade before bending the blade, this is not essential, and the edge of the blade may be such that the tip is located on the upper surface of the blade , An asymmetric initial shape including so-called chisel edges.
[0049]
Modifications of the specifically described embodiments are, of course, possible without departing from the principles of the invention and will be apparent to those skilled in the art. It is, therefore, to be understood that the above-described embodiments are provided as non-limiting examples, and that it is intended that the scope of the invention be limited only by the claims that follow. Should.
[Brief description of the drawings]
FIG.
FIG. 2 is a front perspective view showing a safety razor of the present invention including a blade unit having a blade.
FIG. 2
The front view which shows the blade unit of the razor of FIG.
FIG. 3
FIG. 4 is an end view of the blade unit.
FIG. 4
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2.
FIG. 5
FIG. 3 is a perspective view of a blade unit.
FIG. 6
FIG. 6 is a view showing the blade unit when viewed from the direction of arrow VI in FIG. 3.
FIG. 7
FIG. 3 is an exploded perspective view of the blade unit.
FIG. 8
FIG. 4 is a front perspective view of a blade unit showing a deformed state that can occur during a razor.
FIG. 9
FIG. 6 is a rear perspective view of the blade unit showing a deformed state that can occur during a razor.
FIG. 10
FIG. 7 is a front perspective view showing another deformation state that may occur during a razor.
FIG. 11
FIG. 9 is a rear perspective view showing another deformation state that may occur during a razor.
FIG.
FIG. 2 is a sectional view of a blade unit according to the present invention.
FIG. 13A
FIG. 13 is a schematic view showing a step of continuously molding the blade of FIG. 12 by a pressing operation.
FIG. 13B
The figure which expands and shows the area | region enclosed with the circle of FIG. 13A.
FIG. 14A
FIG. 13 is a schematic view showing a step of continuously molding the blade of FIG. 12 by a pressing operation.
FIG. 14B
The figure which expands and shows the area | region enclosed with the circle of FIG. 14A.
FIG. 15A
FIG. 13 is a schematic view showing a step of continuously molding the blade of FIG. 12 by a pressing operation.
FIG. 15B
The figure which expands and shows the area | region enclosed with the circle of FIG. 15A.
FIG. 16A
FIG. 4 is a cross-sectional view of the blade showing an axis at which a second moment of area is minimized.
FIG. 16B
FIG. 4 is a cross-sectional view of the blade showing an axis at which a second moment of area is minimized.

Claims (33)

A blade for a safety razor blade unit,
An elongated blade element having an upper surface and a lower surface;
A leading edge portion defined by a surface portion having a sharp cutting edge extending along itself and tapering toward a tip of the cutting edge;
A substantially flat blade portion extending rearward from the edge portion and having the upper and lower surfaces parallel thereto;
With
In a transition region between the flat blade portion and the leading edge portion, the lower surface has a convex curvature and the upper surface is concave;
And a cross-section of the blade element along at least a majority of the length of the blade is 1.0 × 10 ^−4. mm ⁴ A blade having the following minimum second moment of area. The minimum second moment of area is 0.5 × 10 ^−4. mm ⁴ The blade according to claim 1, wherein: The minimum second moment of area is 0.35 × 10 ^−4. mm ⁴ The blade according to claim 2, wherein: A blade of a safety razor blade unit,
An elongated blade element having an upper surface and a lower surface;
A leading edge portion defined by a surface portion having a sharp cutting edge extending along itself and tapering toward a tip of the cutting edge;
A substantially flat blade portion extending rearward from the leading edge portion and having the upper and lower surfaces parallel thereto;
With
In a transition region between the flat blade portion and the leading edge portion, the lower surface has a convex curvature and the upper surface is non-convex;
And a plane which bisects a tip of the blade edge is inclined at an angle in a range of 10 to 35 degrees with respect to a center plane of the flat blade portion. 3. A flat plate according to claim 1, wherein the plane bisecting the tip of the blade edge is inclined at an angle in the range of 10 to 35 degrees with respect to the central plane of the flat blade section. Or the blade according to 3. The blade according to claim 4 or 5, wherein the angle of the inclination is in a range of 15 to 30 degrees. The blade according to claim 6, wherein the angle of the inclination is in a range of 20 to 25 degrees. The blade according to any one of claims 1 to 7, wherein the leading edge portion extends rearward from the tip of the cutting blade by a distance of 1 mm or less. A blade for a safety razor blade unit,
An elongated blade element having an upper surface and a lower surface;
A leading edge portion defined by a surface portion having a sharp cutting edge extending along itself and tapering toward a tip of the cutting edge;
A substantially flat blade portion extending rearward from the front edge and having the upper and lower surfaces parallel thereto;
With
In the transition region between the flat blade portion and the leading edge portion, the lower surface has a convex curvature and the upper surface is non-convex, and the leading edge portion is the tip of the cutting edge. A blade extending rearward a distance of 1 mm or less from the blade. The blade according to claim 8 or 9, wherein the leading edge portion extends rearward from the tip of the cutting blade by a distance of 0.5 mm or less. The blade according to any of the preceding claims, wherein the leading edge portion extends rearward from the tip of the cutting blade a distance substantially not exceeding the tapering surface portion. The front edge portion extends rearward from the tip of the cutting edge a distance that is a fraction of the distance that the flat portion extends rearward from the front portion. The blade described in Crab. The upper surface is concave in the transition region;
13. A blade according to any of the preceding claims, wherein the tip of the cutting blade is above the plane of the upper surface of the flat blade portion. A safety razor blade unit comprising at least one blade according to any one of claims 1 to 13. The blade unit has a guard surface,
The at least one blade may have a plane that bisects the tip of the cutting blade formed by an angle formed by a central plane of the flat blade portion and the tangent plane with respect to a tangent plane contacting the cap surface and the guard surface. 15. The safety razor blade unit according to claim 14, wherein the blade unit is arranged to form a large angle. A safety razor blade unit,
Guard surface,
The cap surface,
An elongate blade element having an upper surface and a lower surface; a leading edge portion defined by a surface portion having a sharp cutting edge extending therealong and tapering toward the tip of the cutting blade; and At least one blade extending rearward and having a substantially flat blade portion parallel to the upper and lower surfaces;
With
In a transition region between the flat blade portion and the leading edge portion, the lower surface has a convex curvature and the upper surface is concave;
Thereby, the plane bisecting the tip of the cutting blade is at an angle to the tangent plane contacting the surface of the guard and the cap which is greater than the angle formed by the central plane of the flat blade portion to the tangent plane. A razor blade unit for a safety razor, characterized in that: 17. The safety razor blade unit according to claim 15 or 16, wherein the at least one blade is positioned such that the flat blade portion is substantially parallel to the tangent plane. A blade incorporated in the blade according to claim 13 or the blade unit according to any one of claims 14 to 17,
The blade wherein the edge tip is 0.25 mm above the plane of the upper surface. 19. The blade according to claim 18, wherein a tip of the cutting blade is above a plane of the upper surface in a range of 0.05 to 0.15 mm. 20. A blade according to claim 1, wherein the blade element comprises a metal strip having a bend at the junction of the leading edge portion and the flat blade portion. A blade assembly comprising a plurality of blades defined in any one of claims 1 to 13 or claims 18 to 20,
The blade is such that the cutting edges of the blade are substantially parallel;
And a blade assembly wherein the flat portions of the blades are interconnected such that the flat portions are substantially coplanar. 22. The blade assembly according to claim 21, wherein the blades are interconnected by transverse strips attached to a lower surface of a flat portion of the blade. 23. The blade assembly of claim 22, wherein an elongate flexible guard member is mounted in front of said transverse strip. The blade unit,
A guard surface in front of the blade,
A cap surface behind the blade;
With
And the flat portion of the blade is substantially parallel to a plane tangent to the surface of the cap and the guard,
A blade assembly for a safety razor comprising a plurality of blades as defined in claims 1 to 13 or 18 to 20, or a blade assembly according to claim 21, 22 or 23. A method for manufacturing the blade according to any one of claims 1 to 13,
Providing a substantially flat elongate blade element material having a sharp cutting edge extending along itself and defined by a surface portion tapering toward the tip of said cutting edge;
Bending the blade element blank in an area less than 1 mm behind the cutting blade tip such that the cutting blade tip is spaced from the initial plane of the material. The material has an upper surface and a lower surface, and
24. The method of claim 23, wherein the tip of the cutting blade is displaced to a position above the upper surface plane. 27. The tip of claim 26, wherein the tip of the cutting blade is displaced to a height of 0.25 mm above the plane of the upper surface, preferably in a range of 0.05 to 0.15 mm. the method of. The blade element is bent by pressing between a relatively movable first and second member,
The first member has a flat surface extending forward by a ramp surface;
And the second member has a flat surface that can be freely contacted and separated while facing the flat surface of the first member,
28. The method according to claim 25, 26 or 27. The blade element material is disposed on the flat surface of the first member such that the tip of the cutting blade abuts on an inclined surface,
And the members are moved together such that the portion of the blade element blank disposed between the flat surfaces of these members is pressed flat against the flat surface of the first member.
29. The method of claim 28, wherein: 30. The blade element according to claim 28 or 29, wherein a stopper is provided to abut the leading edge and the trailing edge of the blade element to prevent forward or backward movement of the blade element material with respect to the pressed member. the method of. Machinery used for manufacturing the blade according to any one of claims 1 to 13,
A first member having a flat stamped surface extended forward by an angled inclined surface;
A second member having a flat pressed surface opposite the flat pressed surface of the first member;
Machine equipment characterized in that the members are guided towards and away from each other for pressing the blade element material between them. 23. The machine equipment according to claim 22, wherein a rear stopper that abuts on a trailing edge of the blade element material is provided between the pressed members while the material is pressed. Machine according to claim 31 or 32, characterized in that the inclined surface is defined by a front stop arranged to engage a front edge of the blade element during pressing. .