JPS6244283A - Electric 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 [Technical Field] The present invention relates to an outer blade or an inner blade of an electric razor.

[Background technology]

Until now, electric razor blades have generally been made of stainless steel or nickel alloy as a base material, with a special coating applied to the surface. For example, materials have been used that increase the hardness of the surface by coating the surface of stainless steel with hard titanium nitride using ion vapor deposition technology. However, coating layers created by ion vapor deposition techniques such as ion blasting and ion sputtering have poor adhesion to the base material stainless steel, and therefore the TiN layer formed on the base material surface has poor adhesion to the base material stainless steel.
, CrN, etc. layers were easily peeled off.

In order to eliminate such defects, various special pretreatments have been devised on the surface of the base material, but it has been difficult to perform the treatment uniformly, and it has been difficult to avoid variations in the products. Additionally, there was a problem in that the material was susceptible to rust due to the potential difference generated between the base material and the coating layer.

On the other hand, the coating layer created by the ion vapor deposition technique is usually a thin film on the order of several tens of microns,
Since the base material and the coating layer are clearly stratified, there is a large difference in hardness between the base material and the coating layer.

As a result, when a beard or foreign object hits the cutting edge of the razor blade, the base material deforms plastically and the coating layer gradually peels off from the cutting edge.
There was a problem in that a razor blade with a substantially long life could not be obtained.

In order to solve these problems, for example, a technique has been developed in which the surface of stainless steel or carbon steel is carburized with carbon (see Japanese Patent Publication No. 58-36991). However, in general, as the carbon content of steel increases, its corrosion resistance deteriorates.
When such a material is used as a razor blade, there is a drawback that the surface portion is easily corroded. In order to improve the corrosion resistance of the surface portion, a technology has been developed in which a razor blade is made of composite steel in which the surface layer is clad with a lower carbon steel material than the inside (see Japanese Patent Publication No. 35714/1983). However, if the carbon content is lower than that of the surface layer of the material, problems arise such as having to sacrifice the hardness of the surface and reducing the life of the cutting edge.

Therefore, attempts have been made to solve the above problem by heat-treating such composite steel by heating it to 1000° C. or higher and then quenching it, but this method is still not sufficient.

In addition, with conventional technology, when grinding after heat treatment to form a cutting edge, the surface hardness of the material is low, causing burrs on the cutting edge, which requires special man-hours to remove. There were many problems, resulting in high manufacturing costs.

[Purpose of the invention]

An object of the present invention is to provide a razor blade that has high corrosion resistance, less deterioration in sharpness, long life, and low manufacturing cost.

[Disclosure of the invention]

To achieve the above object, the gist of the present invention is an electric razor blade in which the base material is titanium or a titanium alloy at least in the blade portion, and the nitrogen content gradually decreases from the surface toward the inside.

This will be explained in detail below with reference to the accompanying drawings.

FIG. 1 shows the structure of the vicinity of the blade of an electric razor 1 using the razor blade according to the present invention. FIG. 2 shows the external appearance of the (al outer cutter 2 and (b) inner cutter 3 used in FIG. 1. As shown in FIG. 1, the electric razor I applies a sliding motion to the inner cutter 3. Inner blade 3 that has a drive element 6 inside and slides
The beard is cut (sheared) by an outer blade 2 located at the outer edge of the blade. At that time, a push-up spring is provided inside so that the blade bone can move up and down to make shaving easier if necessary. Outer frame 2 for fixing this to the electric razor body
A blade part 20 having a large number of mesh-like through holes for taking in whiskers is provided inside the blade part 1.

As shown in FIG. 2(b), the inner cutter 3 is made up of a large number of arc-shaped blade portions 31 provided at regular intervals.

The blade portion is nitrided as follows.

FIG. 3 schematically shows the manufacturing process of the outer blade 2 for an electric razor. The base material is titanium (including titanium alloys), which has high elongation and is easier to form into uneven shapes than ordinary stainless steel.

A thin plate annealed material (the same applies hereinafter) was used, and by press working or the like, a blade plate 7 having a blade portion 20 having an uneven cross-sectional shape as shown in FIG. 3(a) was obtained. Next, the molded blade plate 7 was placed in a treatment tank to perform vacuum nitriding treatment. A commercially available vacuum nitriding apparatus was used. After the inside of the processing tank in which the blade plate 7 was placed was brought to a high vacuum of 10-'' torr or less, the temperature was gradually increased, and when the temperature reached about 850° C., nitrogen gas was introduced into the processing tank.

The treatment tank was kept as it was for about 30 minutes, and then cooled in the furnace without opening the inside of the treatment tank. A diagram of the vacuum nitriding process at this time is shown in FIG. In FIG. 4, the time elapsed from when the blade plate 7 is placed in the processing tank until it is heated is omitted. The reason why the nitriding temperature is set to about 850° C. is to perform the nitriding treatment in a short time on the surface of the titanium material which is activated below the transformation temperature of titanium. The retention time in this case is 30
Preferably within minutes. When the holding time is kept at the above temperature for 30 minutes or more, nitriding progresses from the outer surface to the center of the blade plate 7,
This is because most of the blade plate 7 becomes a brittle T i N z layer or TiN layer, which tends to cause practical problems such as easy breakage during use.

In addition, the vacuum nitriding treatment conditions correspond to the thickness of the blade plate 7.
The temperature increase rate, heating holding temperature, holding time, nitrogen gas amount, cooling rate, etc. can be selected to be controlled as appropriate.

The cross-sectional shape of the blade plate 7 after the vacuum nitriding treatment is shown in FIG. 3(b). Through this treatment, nitrogen diffused and permeated from the surface of the blade plate 7 and reacted with the titanium base material, forming a compound layer corresponding to the nitrogen concentration from the surface to the center. Figure 5 (
81 conceptually shows the distribution of nitrogen content in the nitride layer formed on the surface of the blade plate 7. A layer with a large amount of T1Nz, a layer with a large amount of TiN, and a layer with a large amount of T+zN were successively formed from the surface, resulting in a multilayer structure in which the Ti layer, which is the base material, remained in the center. At this time, the hardness (HV) of the outermost layer, which is a layer with a large amount of TiN, is 1800 or more, and the Ti
The hardness (HV) of the layer was approximately 200.

According to such a nitriding method, the hardness of the outermost surface of the blade plate 7 is high, and the hardness decreases continuously toward the center of the blade plate 7, and conversely, the hardness of the razor blade is high in the center. is obtained. In addition, compared to the ordinary nitriding process, which takes several tens of hours, the vacuum nitriding process described above can obtain the desired razor blade in a very short time, as shown in Figure 4, which improves productivity. It is convenient to improve and reduce manufacturing costs.

The surface of the nitrided blade had a golden color. This seems to be due to the titanium nitride compound on the surface.

The blade plate 7 that has been subjected to the nitriding treatment is then ground on its surface to form a blade hole 8, as shown in FIG. 3 (C1).A cutting edge 9 is formed on the ground surface 10 of the blade plate 7. Hail. The cutting edge 9 part is shown in Fig. 5(b).
As we will see, the nitride layer with the highest hardness (T i N
z layer). Since the outermost layer is composed of such a hard and brittle nitride layer, there is little plastic flow of the material when grinding the blade plate 7, and as a result, the cutting edge does not curl.

〔Effect of the invention〕

Since the electric razor blade according to the present invention has the above structure, the base material and the nitride layer on the surface do not separate, and the base material with high toughness absorbs the impact applied to the cutting edge. Therefore, no chipping occurs at the edges. As a result, the sharpness of the razor blade does not deteriorate even after long-term use, and its lifespan is extended. On the other hand, titanium, which has excellent corrosion resistance, is used as the base material, and a nitride layer whose nitrogen concentration gradually decreases from the surface is uniformly formed, so a razor blade with excellent corrosion resistance can be obtained.

The electric razor blade according to the present invention has a short time required for an annealing cycle when manufacturing it, and has high productivity.
Manufacturing costs can be lowered. In addition, when grinding the razor blade after heat treatment, almost no burrs occur, so there is no need for special man-hours to remove burrs, which was required in the prior art, and from this point of view, the present invention The manufacturing cost of electric razor blades will be low.

Further, since the electric razor blade according to the present invention has a golden yellow nitride layer on its surface, it can give the product an image as a luxury product and increase its commercial value.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an electric razor using the electric razor blade according to the present invention, and FIG. 2 (al is a perspective view of the outer blade of the same electric razor as above, and FIG. FIGS. 3A and 3B are perspective views of FIGS. 3A and 3B. FIGS. 3C is a diagram showing the manufacturing process of the electric razor blade according to the present invention, and FIGS. (bl is a cross-sectional view of the blade plate after vacuum nitriding treatment, (C
) is a cross-sectional view of the blade plate after the surface has been ground, FIG. 4 is a diagram showing an embodiment of the vacuum nitriding method for electric razor blades according to the present invention, and FIG. It is an enlarged sectional view conceptually showing the nitride layer on the surface of the blade plate after vacuum nitriding treatment, (bl is an enlarged sectional view conceptually showing the nitride layer on the surface of the blade plate after being ground. 1. ...Electric razor 2...Outer blade 3...Inner blade
20...Habe agent Patent attorney Takehiko Matsumoto Figure 1 Figure 3 Figure 5 (a) Procedural amendment (October 1985 4 Hita m60 Togo Nan [186343 No. 2, Title of invention Relationship between electric razor blade 3 and the body of the person making the correction Patent applicant Address 1048 Kadoma, Kadoma City, Osaka Name (583) Representative of Matsushita Electric Works Co., Ltd. ((3m position Sadao Fujii 4, no agent) , -・＼ 6. Specification to be amended 7. Contents of amendment (11. In the 13th line of page 2 of the specification, "several tens" is corrected to "number."

Claims (1)

[Claims] (1) An electric razor blade in which the base material is titanium or a titanium alloy at least in the blade portion, and the nitrogen content gradually decreases from the surface toward the inside.