JPS59502135A - razor blade - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] razor blade Technical field TECHNICAL FIELD This invention relates to razor blades, and more particularly to the shaping of cutting edges.

The present invention defines the shape of the cross-section within the first 40 micrometers measured from the distal lip. is a widely used razor blade with a cutting edge determined by the official W-ad. do. Here raw is the distance from the tip (micrometers), field = given distance car The width of the tip (the width of the edge C micrometers), 1 is greater than 0.8 , and is a power exponent with a value smaller than 0.75; from 40 micrometers to 100 micrometers from the terminal edge. The included angle between the tip facets within the band ranges from 7° to 14°, preferably between 9° and It is within the range of 1 to 0.

in range.

Blades with these tip features will warp better in comparative warp tests, but will not have a reasonable useful life. It was known to be strong enough to give life.

Background technology The background prior art will be explained in some detail to provide a proper understanding of the features of the present invention. It is convenient to illustrate it as follows. In the attached drawing, FIG. 1 is a highly enlarged view of a typical or average shaped blade tip.

FIG. 2 is a diagram of the shape of the tip, illustrating the principle of "chord-width" measurement.

Figure 3 is a thick depiction of the facial hair cut off.

Figures 4 through 7 show various blades currently on the market from various manufacturers. This is a cross-section of

Figure 8 shows the shape of the tip described in British Patent Specification No. 1465697 from Figure 4. This figure is similar to the figures up to Figure 7.

The cutting edge of a razor blade consists of successive pairs (usually 3) of different included corner facets. is sharpened by grinding it onto a strip of steel with a suitably placed grinding wheel. be destroyed. The cross section of such a lip is shown in Figure 1 with typical values of dimensions and angles. and is conventionally described as the "edge of three facets".

While the last pair of facets is being ground (this step is commonly called "grinding") ), the deflection of the strip in the grinding machine is determined by the mechanical This creates a final facet that is not normally flat but slightly convex. Curvature , steel and grindstone AA used as well as the adjusting parameters of the sharpening machine. last facet Due to the convexity of the saw, the cross section of the tip of the blade in this zone is customarily known as ``Gothic art. It is called "chi-shaped". Due to the curvature, the tip of the blade is determined by just one parameter. Since this part cannot be determined precisely geometrically, various distances from the edge The characteristics of the shape are expressed by determining the width of the "tip" or "string" of the It's normal. One alternative method is to use the mathematical equation for each half of the cross section of the facet. It is to apply to form. These methods are illustrated in FIG.

During use, the razor blade is held in the razor at an approximately 25° angle, and the edge When the edge meets the beard, it should be helped by the interrupting action. It is moved over the face, as if to go in and cut it off. whiskers (diameter on average The cut portion (approximately 100 micrometers) is only about half the diameter of the beard. Something that is pressed against a facet of the blade that is far from the facial skin surface in order to penetrate. I believe that. From now on, the whiskers should be moved away from the blade to reduce the cutting force. It can be bent and tightened. Push through the reaction between the whiskers and the facets of the blade The resistance to penetration is therefore about the first 50 m from the edge to the tip of the blade. O meters only, and the height of the tip of the blade in this zone (・1, cutting seems to be the most important from this point of view. This is shown in FIG.

Reducing the angle included in the facets means that the tip of the blade can continuously enter into the whiskers. It is obvious that the resistance to the load will be reduced accordingly. However, if the angles involved are If made too small, the strength of the blade tip will not be able to withstand the bending forces created at the edge during cutting. and the tip is plastically deformed (or the machine of the material from which it is made) (brittle and break due to its mechanical properties) and may permanently break, impairing subsequent cutting performance. In other words, the edges become "dull."

The tip of the blade is strong enough to prevent breakage caused by such bending. In order to design a suitable shape for the edge, the magnitude of the bending stress applied during whisker cutting is estimated. A pile was created. Knowing these values and the yield strength of the steel from which the blade is made, , the minimum dimensions of the tip section can be calculated. The stress applied during cutting is It seemed to arise from the viscoelastic flow of thick whiskers passing through the tip of the .

Currently manufactured blades have tip geometries of certain dimensions that are less than these minimums; Has a normal shaving life (versus blades made from stainless steel for conventional razor blades) It is known that the blade becomes dull due to bending over an average of about 10 days). .

Applicants have proposed a specific range from O micrometers to 40 micrometers from the edge. Edge geometry of fixed zone 5 By carefully controlling the Possesses strength suitable for resisting cutting performance and warping while maintaining satisfactory durability. We have now discovered that it can be made smaller so that customer satisfaction is improved.

The shapes of the blade tips of various manufacturers currently on the market are shown in Figures 4 to 7. and FIG. 8 shows the shape of the tip of the blade as described in British Patent No. 1465967. shows.

These known blade tip shapes are shown in FIGS. 10 and 10A for the preferred blade tip of the present invention. It is compared with the shape of the edge.

In one form of the invention, the cross-section of the tip of the blade initially includes three facets as shown in FIG. narrowed by grinding to a smaller contained corner. This is a cross The surface is narrower throughout and, importantly, the area is narrower, which is especially important during beard cutting. narrower lateral distances from O micrometers to 40 micrometers from the Create the tip of the cross-section blade. Such edges may be too weak to withstand stress during shaving. Too much, and must be further modified.・This is the fourth sharpening stage. This is achieved by adding . It is an interlocking disc that rotates or is abrasive around the Uses a spiral of textured leather or synthetic leather (commonly referred to as a "strop") It is done as follows. The sharpened blade passes through the strop, which polishes the facets and Remove a small amount of steel from the surface of Change the dimensions of "Gothic Arch". This stage is called "sharpening".

The flexibility of the leather in the strop allows it to be attached to the tip of the sharpened blade (while allowing it to adapt). Therefore, the abrasive sharpener increases the curvature of the last small plane near the bottom, but The effect on the plane shape is small.

The blade is sharpened at the suitably reduced included corner of the facet and then suitably sanded. When being honed, the shape of the tip is such that the width of the string near the edge is not as sharp as before. While the width of the string further from the edge can be changed to be larger than that of the edge, It was found that the edges remained smaller than those with conventionally sharpened edges. this is , it makes the tip of the blade near the edge stronger than normal, so it is added to it while cutting the beard. The bending stress that is applied can be better resisted while the The cut out part presents less resistance due to intrusion during cutting, thus cutting Make it easier.

The radius of the last tip of the lip may be determined, for example, from Patent Specification Letter No. 1.378,550 (U.S. 3,761,374), smaller than 1000°A and preferably Preferably, it should have an average value smaller than 500'A and be like a conventional one. No. i.e. it must be within the normal range of a conventionally sharpened edge. stomach.

Disclosure of invention The blade according to the invention shows superior shaving performance when compared with conventional blades in standard shaving tests. It was found that it has warpage performance.

One shape of the blade according to the invention and the way it is formed is shown below by way of example in FIG. , FIG. 10, and FIG. 11 are explained in detail.

FIG. 9 is a schematic diagram of the leather sharpening operation of the tip of the blade.

Figures 10 and 10A are comparable to the known blade tip shapes shown in Figures 4 to 8. 2 shows the shape of the tip of the blade according to the present invention in comparison. Figure 10A is enlarged from Figure 10. It's a small detail. and Figure 11 shows the width of the chord ``W'' at different distances ``d'', plotted on a logarithmic scale. This is a graph of No. 11.

A strip of stainless steel for razor blades with a nominal composition of ROM 13 and 0.6% carbon. , hardened and tempered by conventional methods, and formed into a three-plane structure shown in FIG. However, it is not manufactured in the traditional manner by grinding and sharpening to create the finished hem. Sharpened with included corners that are smaller than the one above. The blade is like a traditional abrasive sharpener, A piece of artificial leather with a fine alumina abrasive on its surface is passed between rotating strops. Here, the corner set in the strop (it is the intersection of the strop as shown in Figure 9) is the included angle between their tangents. ) has a scent in the range from 60° to 4°. It was. The facets are overcoated with a fluorinated hydrocarbon material (UK Patent No. 906.005). Metal coatings of alloys of chromium and platinum (as described in the US Patent No. No. 3,829,269).

Grinding, sharpening, and sanding methods are peripheral to the technology, but are less traditional. such as by passing the strips between suitably shaped dies or rollers. , or deformed by electrolytic or chemical decomposition molding, or by ion bombardment molding It will be appreciated that this can be used to sharpen the tip.

The cross section of the blade tip was measured using optical interferometry. The blade is , placed under the objective of a metallurgical microscope fitted with a Michelson interferometer, It can be seen at a magnification of about 100x. The interferometer was oriented perpendicular to the edge of the blade. Adjusted to produce stripes. The blade is moved so that the stripes reveal the condition of the facets of the blade. tilted at an appropriate angle so that The spacing of the stripes varies depending on the movement of the stripes from the edge. adjusted so that it can be easily measured at a certain distance. If you know the angle of inclination , the shape of the tip is obtained from the sum of the movements of these stripes measured at corresponding positions on each side of the blade. Calculated.

These results are shown in Figure 10, where the first 40 micrometers The spread of the preferred blade tip cross-section across the le is indicated by the dark shaded band. , and the extent of the known blade cross-section is indicated by the band containing the cross-section line.

In this particular example, the width of the string (W) at the distance (d) from the distal lip is: It seemed like

d (micrometer) W (micrometer) 4.0 1.86-2.1 6 8.0 3.0 5 - 6.52 20.0 6.12-6.85 30.0 8.43-9.52 40.0 10.73-12.11 The geometry of this cross section uses a logarithmic scale of tip thickness as a function of distance from the lip. and the resulting plot is shown in Figure 11, then It can be seen that the drawn points form a straight line.

From the slope and intercept of the straight line, the shape of the tip can be determined by the equation W-ad . where 2 is a proportionality coefficient not greater than 0.8, and 1 is less than 0.75, More specifically, it is a power index having a value in the range of 0.65 to 0.75.

Measured known blades have a power index (or slope) ranging from 0.76 to 1.0. ) was found to have an optimal straight line with

A smaller slope is a key feature of the invention, and the blade tip of the invention Relatively thick and strongly arched near the distal edge compared to those of the technique. but is relatively thin at the rest of the tip.

Small plane in the zone from 40 micrometers to 100 micrometers from the tip The included angle is from 7° to 12°, or from 7° to 1 It can even be up to 4°.

The tip shapes above are for stainless steel blades, and for sapphire, charcoal Quite thin for harder blade materials like titanium chloride, or diamond. I want to be understood as something that can be done.

To create a comparable tip shape from a material harder than stainless steel, applicants The corresponding chord is inversely proportional to the square root of the yield strength of the material, which is harder compared to stainless steel. Reduce the width of. For example, for diamonds, the string width is calculated for stainless steel. Approximately 40 centimeters of the total.

In addition, the stainless steel blade tip zone is harder and has higher yield strength than stainless steel. be coated with a material that has

In such cases, the string international search report given by the basic equation ANNEX To ThP-INTERNATIONAL 5EARCHREP ORT 0rNGB-A-125834830/12/71 None 1st page continuation 54 Ford Avenue

Claims (1)

[Claims] 1. Using a razor blade with a stainless steel cutting edge, cut the end edge. The shape of its cross section up to a distance of 40 micrometers is given by the equation %formula% A razor blade characterized by: Here W is the distance from the tip of the blade (in micrometers) the thickness of the chord (in micrometers), the soil has a proportional coefficient not greater than 0.8, and Tetan is 0.65. It is a power index having values ranging from 0.75 to 0.75. 2 At least the tip of the blade is made of a material having a higher yield strength than stainless steel. The razor blade according to claim 1, wherein the razor blade is modified into a razor blade according to claim 1, wherein the razor blade is The width obtained from the formula 2 is the yield strength of the harder material, that of stainless steel. A razor blade characterized in that it is reduced in inverse proportion to the square root of its ratio. 3. The tip of the cutting edge is made of a material with a yield strength greater than that of stainless steel. A razor blade according to claim 1 modified by being coated, wherein the front A razor blade characterized by being centered. Here is the yield strength of the hard coating is the ratio of y to that of stainless steel, and W is also the ratio of y to that of stainless steel. Equation for (micrometers) %formula% to satisfy. 4. In the razor blade according to claim 1, the tip of the blade is A small plane at a distance between 40 micrometers and 100 micrometers from the edge of were created, and the facets ranged from 7° to 12°, and then 1°. preferably converging towards said edge at an included angle ranging from 9° to 11°. A razor blade characterized by: