RU2008145761A - LOWER KNIFE FOR HEAD OF ELECTRIC RAZOR - Google Patents

Abstract

The present invention relates to a lower cutter (4) for a shaving head, equipped with an upper cutter (7), of an electric razor, comprising at least one blade (10) which has a cutting edge (11) pointing in a direction of movement. The invention also relates to a shaving head having such a lower cutter and to an electric razor equipped with it. It is proposed to no longer give the cutting edge the conventional wedge-shaped configuration in which simply two planes inclined at an acute angle define the cutting edge contour. According to the invention, the cutting edge has, one behind the other in the direction of movement (16), at least two cutting edge sections (18,19) having different cutting angles. By means of a cutting angle graduation or a changing cutting angle, an optimum compromise can be achieved between the conflicting requirements of cutting behaviour and edge stability. The cutting edge section having the more obtuse or less acute cutting angle produces the desired cutting edge stability and at the same time provides for a long service life. On the other hand, the cutting edge sections having the more acute angle reduce the cutting forces, such that an improved threading behaviour can be achieved.

Claims (27)

1. The lower knife for the cutter head of an electric razor equipped with an upper knife (7) with at least one blade (10) that has at least one cutting edge (11) facing at least one direction (16) of movement, characterized in that the cutting edge (11) in the direction of movement has at least two sections (18, 19, 21) with different angles (φ ₁ , φ ₂ , φ ₃ , ... φ _n ) cutting arranged one after another. 2. The lower knife according to claim 1, characterized in that the first section (18) of the cutting edge with the first angle (φ ₁ ) of cutting in the direction (16) of movement is followed by at least one second section (19) with another, smaller cutting angle (φ ₂ ). 3. The lower knife according to claim 2, characterized in that the second cutting section (19) is followed by other cutting angles φ _n , and for all angles φ the following relation is true: φ _n <φ _n-1 . 4. The lower knife according to claim 3, characterized in that the previous cutting angle (φ _n-1 ) is at least 10 ° greater than the subsequent cutting angle (φ _n ). 5. The lower knife according to one of claims _{1 to 4} , characterized in that the angles (φ ₁ φ _n-1 ) of cutting the sections (18, 19, 21) of the cutting edge are respectively less than 90 °, preferably less than 65 °. 6. The lower knife according to claim 1, characterized in that the first cutting angle is 45 ° +/- 15 °, and / or the second cutting angle is - 25 ° +/- 5 °. 7. The lower knife according to claim 1, characterized in that each of the sections (18, 19, 21) of the cutting edge is approximately wedge-shaped with flat or concave or convex sides of the wedge in longitudinal section (B-B). 8. The lower knife according to claim 1, characterized in that the sections (18, 19, 21) of the cutting edge, when viewed in the direction (16) of movement, have different lengths (ε ₁ , ε ₂ , ... ε _n ). 9. The lower knife according to claim 1, characterized in that the first section (18) of the cutting edge in the direction of motion (16) has a length (ε ₁ ) in the direction of motion (16), which is less than 50 μm, preferably less than 25 μm. 10. The lower knife according to claim 9, characterized in that the length (ε ₁ ) of the first section (18) of the cutting edge is approximately 5 μm. 11. The lower knife according to claims 8-10, characterized in that the sum (E) of lengths (ε ₁ , ε ₂ , ... ε _n ) of all sections of the cutting edge in the direction (16) of movement is more than 50 μm, preferably more than 100 μm . 12. The lower knife according to claim 1, characterized in that the cutting edge (11) hangs in relation to the upper side (13) of the blade, which by definition faces the upper knife (7). 13. The lower knife according to claim 12, characterized in that the cutting edge (11) extends at one or more angles (α) overhang with respect to the upper side (13) of the blade. 14. The lower knife according to item 13, wherein the following relation is valid for each angle of drooping: α _{i + 1} <α _i (i = 1, ... n-1). 15. The lower knife according to 14, characterized in that all the angles (α ₁ - α _n ) of the overhang lie in the range from 0.5 to 45 °. 16. The lower knife according to 14 or 15, characterized in that the height difference (D) between the highest point of the upper side (13) of the blade and the cutting edge (17) of the cutting edge (11) is from 1 to 20 μm, more preferably less 10 microns. 17. The lower knife according to claim 1, characterized in that the blade (10) has two opposing cutting edges (11). 18. The lower knife according to claim 1, characterized in that there are many blades (10), preferably located parallel to each other. 19. The lower knife according to claim 1, characterized in that the lower knife (4) is made in the form of a shaped part from sheet metal. 20. The lower knife according to claim 1, characterized in that the lower knife (4) and / or at least the cutting edge (11) are made by etching. 21. The lower knife according to claim 1, characterized in that the lower knife (4) and / or at least the cutting edge (11) are made by electrochemical etching, embossing, grinding, electroplating or injection molding. 22. The lower knife according to claim 1, characterized in that the blade (10) at least partially has a protective coating to protect against wear. 23. The shaving head of the electric shaver with the lower knife (4) according to one of claims 1 to 22. 24. Electric shaver with a shaver head according to item 23. 25. An electric shaver according to claim 24, wherein the lower knife (4) is mounted rotatably. 26. An electric shaver according to claim 24 or 25, wherein the lower knife (4) is mounted so as to be oscillatoryly movable. 27. An electric shaver according to claim 24, wherein the lower knife (4) can be driven into linear oscillatory motion.