JPH0549307B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to the blade of a reciprocating electric shaver, and particularly to the shape of the inner blade that slides into sliding contact with the inner surface of the outer blade that is attached in a curved state.

[Conventional technology]

Some reciprocating electric shavers have an outer blade with numerous blade holes made of a thin, flexible metal plate, and are attached to an outer blade frame in a semi-cylindrical shape. . in this case,
The inner blade whose periphery is in sliding contact with the inner surface of the outer cutter is generally shaped so that its periphery forms an arc, but when the outer cutter is curved, it is difficult to define an accurate arc. In order not to become
A gap is created between the inner cutter and the outer cutter. For this reason, regarding the shape of the peripheral edge of the inner blade, Japanese Patent Application Laid-Open No. 116393/1983 describes a hyperbolic cosine shape, and Japanese Patent Application Laid-Open No. 136976/1989 describes a curve expressed by a cubic polynomial. It has been proposed to approximate.

[Problem to be solved by the invention]

However, even when the periphery of the inner blade is shaped to draw these curves,
The curve drawn by the semi-cylindrical outer blade does not match perfectly, and a gap is created between the outer blade and the inner blade, making it difficult to shave well. The present invention has been made in view of these points, and its purpose is to provide a reciprocating electric shaver blade that has good adhesion between the inner blade and the outer blade and has excellent sharpness. It is in.

[Means to solve the problem]

Therefore, the present invention has an outer cutter which is provided with a large number of cutter holes for introducing whiskers and is curved in a semicircular shape and is attached to an outer cutter frame, and the peripheral edge of the inner cutter blade is brought into sliding contact with the inner surface of this outer cutter. The inner cutter blade is characterized in that the curve drawn by the peripheral edge of the inner cutter blade is a curve represented by a sixth-order polynomial. [Operation] According to the present invention, by setting the curve of the peripheral edge of the inner cutter blade in a curved shape represented by a sixth-order polynomial, the gap between the outer cutter and the inner cutter blade can be made very small. be able to. [Embodiment] The present invention will be described in detail below based on the illustrated embodiment. The outer blade 1 in which a large number of blade holes 10 for introducing whiskers are formed is made of a thin flexible metal plate. , a plurality of positioning holes 11 are provided at each end thereof. The outer cutter frame 2 that holds the outer cutter 1 is formed of a holding frame 20 and a mounting frame 25 here.
The holding frame 20 is provided with a plurality of positioning protrusions 21a and 21b on the outer surface of both side surfaces, a through hole 22, and a connecting portion 23 on the outer surface of both end surfaces.
The outer cutter 1 has positioning protrusions 21a of the holding frame 20 in the positioning holes 11 at both ends thereof.
21b is inserted, the thin plate-like mounting plates 3 are placed on each end portion, so that the holding frame 20 is attached to the holding frame 20 in a semicircularly curved state. The mounting plate 3 here has holding frames 2 on both ends thereof.
0 through the through hole 22 and bent on the inner surface side of the holding frame 20.
The outer cutter 1 is held between the outer surface of the holding frame 20 and the outer cutter 1 is provided with a groove 31 on the side facing the holding frame 20 for allowing the plurality of positioning protrusions 21a and 21b to escape. On the other hand, the mounting frame 25 in the outer blade frame 2 is
It is attached to the main body 5 in which the motor and the drive element 50 that converts the rotation of the motor into reciprocating motion are housed, and the connection provided in the holding frame 20 is connected to the engagement grooves 26 formed at the top of both ends of the main body 5. Part 2
3 is inserted, and the hook 24 in the connecting part 23
By engaging, the holding frame 20 is connected. On the other hand, the inner cutter 4 has a large number of inner cutter blades 40.
It is composed of a base 41 on which these inner blades 40 are mounted parallel to each other on the upper surface side, and a joint 42 protruding from the lower surface of the base 41, and the joint 42 is attached to the drive element 50, The peripheral edge of the inner cutter blade 40 comes into sliding contact with the inner surface of the outer cutter 1 while being biased by the push-up spring 51, so that the outer cutter 1
The inner blade 40 is used to cut the whiskers introduced into the interior through the blade hole 10.
The curve drawn by the periphery, which is the cutting edge, is a 6th degree polynomial,
In other words, y=a ₆・x ⁶ +a ₅・x ⁵ +a ₄・x ⁴ +a ₃・x ³ +a ₂・x ² +
It is said to be a curve expressed as a ₁ x + a ₀ . In general, the outer cutter 1 curved into a semicylindrical shape is expressed by a third-order polynomial based on the deflection equation of material mechanics, but in reality, the outer cutter 1 has a large number of cutter holes 10 and the deflection is extremely large. Furthermore, as shown in FIG. 3, a large error occurs between the curve expressed by the third-order polynomial and the actually curved shape of the outer cutter 1. Furthermore, this figure 3 shows the relationship between the order and the error when the outer cutter 1 is approximated by a polynomial. (in the left and right direction in the figure, y is the up and down direction in the figure) When the coordinate origin is taken as the origin, it is the average of the sum of squares of the difference between the actual measurement value y and the approximation formula y for a certain xi, and the smaller the value, the closer it is. High accuracy. Here, as is clear from Figure 3,
The shape of the outer cutter 1 curved into a semicylindrical shape can be best approximated by the sixth order or higher,
Further, even if the order is increased to the sixth order or higher, the degree of approximation remains almost constant and is almost saturated at the sixth order. The broken line in the figure shows the case of approximation using the hyperbolic cosine shape shown in the conventional example, that is, y=a.cosh.x/a (a is a constant), and the degree of approximation is quite poor. For this purpose, if the shape of the cutting edge, which is the periphery of the inner blade 40, is formed by a curve represented by a sixth-order polynomial, as shown in FIG. If it is formed with a curved line from point A to minimum point B as the apex to the inflection point C, it will best adhere to the inner surface of the outer cutter 1, which is curved in a semicylindrical shape. , good sharpness can be obtained. In addition, when the inner blade 40 is formed by a curve expressed by a sixth-order polynomial in this way, when the slope of the tangent to the cutting edge, which is the peripheral edge of the inner blade 40, is θ, this slope θ is the inner blade. The shape increases monotonically as the distance from the top of the blade 40 increases.

【Effect of the invention】

As described above, in the present invention, since the curve of the peripheral edge of the inner blade is set to the curve shape shown by the sixth-order polynomial, the outer blade has a large number of cutting holes and is curved in a semicircular shape. The gap between the blade and the inner blade can be made very small, and the degree of adhesion between the two can be maintained well, and for this purpose, the blade must have excellent sharpness. I can do it.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of one embodiment of the present invention, Fig. 2 is an exploded perspective view of the same as above, Fig. 3 is a characteristic diagram showing the correlation between degree and degree of approximation, and Fig. 4 is expressed by a sixth-order polynomial. 1 is an explanatory diagram of the curves shown in FIG.

Claims (1)

[Claims] 1 Consists of an outer blade that is curved in a semicircular shape and is attached to an outer blade frame with a large number of blade holes for introducing whiskers, and an inner blade that slides the periphery of the inner blade onto the inner surface of the outer blade. Further, a reciprocating electric shaver blade characterized in that the curve drawn by the peripheral edge of the inner blade is a curve represented by a sixth-order polynomial.