JPH0376201B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing razor blades using zirconia powder. [Conventional technology] Commercially available razor blades are originally made of stainless steel, but in order to improve the durability of the razor's sharpness compared to stainless steel blades, razor blades are made of ceramic that does not rust and has high hardness and toughness. It is preferable to make a blade. Ceramics used as materials for razor blades include alumina, zirconia, metal composite ceramics, and single crystal alumina. The suitability of these ceramics as materials for razor blades was investigated and the results are shown in Table 1 below.

[Table] Single-crystal alumina and zirconia have the best cutting edge condition, and when compared with single-crystal alumina and zirconia, zirconia is superior in terms of toughness. In addition to zirconia, as the zirconia molding material, two-component or three-component materials in which zirconia is the main component and calcium oxide, magnesium oxide, cerium oxide, alumina, etc. are added thereto can also be used. When manufacturing razor blades using this zirconia, the most important thing is that the following conditions are met. That is, thin plate properties, high density, homogeneity, economy, and mass production. The razor material needs to be as thin as possible. This is to shorten the grinding time and increase mass productivity. Also, high density and homogeneity are the most important points when making a blade. If there is variation in high density, the straightness of the cutting edge cannot be achieved, resulting in waves and poor cutting quality. In addition, economic efficiency and mass production are important points for industrial products. When we consider the manufacturing methods of razor blanks, taking into account these factors, we find that the two sheet manufacturing methods are slip casting and consolidation.
Cast) is considered to be the most suitable method, but a comparison of these and other methods is as shown in Table 2 below.

[Table] Thinness and homogeneity are inferior in casting, while homogeneity is inferior in consolidation, but the productivity is noteworthy. On the other hand, with the hydrostatic pressure method or the hot press method, there is no problem in terms of quality, but the economic efficiency (mass production) is extremely poor. Due to these circumstances, razor blades made of zirconium were not commercialized. [Problems to be Solved by the Invention] First, one of the inventors of the present application has developed a method for molding ceramics that has excellent formability, shape retention for demolding from molds, high density, homogeneity, and economic efficiency. Invented the fluid compression molding method and published Japanese Patent Application Laid-Open No. 60-30312 (Patent Application No.
58-136845), but discovered that this molding method could be applied to molding razor blades using zirconia/liquid composite molding material, and decided to solve the homogenization problem in the compression molding method. Successful. [Means for Solving the Problems] According to the method of the present invention, a zirconia/liquid composite molding material is once shaped into a razor blade shape under a fluid state in which it can exhibit liquid properties, and then It is characterized by placing the shaped body under a condition in which it can exhibit solid properties by confining it under a condition in which it cannot flow, and after compacting it again to achieve homogenization, demolding, firing, and cutting. A method of manufacturing a razor blade is provided. An example of a zirconia/liquid composite molding material that can be applied to the method of the present invention is zirconia powder (Zr ₂ O ₃ , purity 98.0%, average particle size 20 μm), tap water as the liquid, and thixotropic PVA as a feeding aid
Using a saturated solution, the amount used is 0.1 relative to the amount of powder.
% by weight, and 0.0% by weight of CMC and liquid emulsion (trade name: Maxelon).
For example, 0.2% by weight of water may be added and kneaded, and 2 to 7% (as an example) of water may be added thereto. The clay after this adjustment has sufficient properties for fluid consolidation molding. That is, the above-mentioned adjusted clay can undergo creep deformation (creeping deformation, flow deformation as a liquid) at a sufficiently slow deformation rate of, for example, 0.5 cm/sec.
It has special mechanical properties that allow it to undergo plastic deformation at a deformation rate sufficiently faster than cm/sec. Next, a molding method using a fluid compression molding method will be explained.
Using zirconia adjustment clay, insert the clay 3 between the upper inner cylinder 1 and the lower inner cylinder 2 in the outer cylinder 4 of the mold as shown in Fig. 1, and adjust the outer cylinder 4 by moving it up and down. ,
The six pores 5 radially provided in the outer cylinder are arranged at the middle position of the clay pillar. First, the upper inner cylinder is lowered so that the clay column undergoes creep deformation at a sufficiently slow deformation rate, and the clay is fluidized and consolidated. Due to this creep deformation, a part of the clay is discharged out of the system through the pores. At this time, the outer cylinder is rotated at a speed of, for example, 0.1 revolutions/minute,
Discharge of clay can be made uniform in the circumferential direction. When the thickness of the clay 3 reaches a predetermined thickness as shown in FIG. 2, the lowering of the upper inner cylinder is stopped to stop the flow deformation. Next, move the outer cylinder 4 to the upper position,
The molded body is confined in a state where the clay is not discharged, and the upper inner cylinder is pushed down at a sufficiently fast speed so that the clay undergoes plastic compaction as shown in FIG. At this time, the non-uniformity of the liquid filled between the powder particles is eliminated by compaction deformation, and a homogenized molded body is obtained. Lower the outer cylinder and pull up the upper inner cylinder to take out the molded body. The zirconia molded body thus obtained by the fluid compression molding method has characteristics suitable as a molded body for razor blades. In other words, thin plates up to 0.1mm thick are possible. Usually 0.5
mm. High density: The density can be increased to about 99% of the theoretical density of 6.3 after firing. Homogeneity: Obtains values that exceed those of consolidation molded, CIP molded, and HP molded products. , satisfies economic efficiency and mass production. Hereinafter, the present invention will be specifically explained with reference to Examples. [Example] 3 moles of ittria (Y ₂ O ₃ ) were mixed with 100 moles of fine powder zirconia (ZrO ₂ purity 99.00%), and 0.1
Add 0.1% by weight of CMC, 0.1% by weight of PVA, 0.2% by weight of liquid/liquid emulsion (trade name: Maxelon), and add 2% of water.
The mixture was added to a concentration of ~3% by weight and thoroughly mixed to form a molding raw material. This was inserted into a rectangular mold with a horizontal cross section of 30 mm x 20 mm, and set as shown in FIG. Next, the upper inner cylinder was pushed down at a deformation speed (0.01 cm/sec) at which the clay 3 could exhibit creep deformation, and when the clay pillar reached a predetermined thickness of 0.5 mm, the lowering was stopped. Next, as shown in Figure 3, the molding frame was reset, and the clay was reconsolidated at a fast deformation rate (1.0cm/sec) that allowed the clay to behave as a solid. We aimed to improve homogeneity by eliminating unevenness in the water content. The above operations were performed under vacuum to prevent degassing and ingress of outside air. Demolding was carried out without any problems, and the sillage after demolding was fired at 1600°C for 2 hours to obtain a razor material. This 0.5 mm thin plate was sharpened using the following polishing process. 1 Diamond grindstone #180 2 Same abrasive grain #500 3 Same abrasive grain #3000 4 Diamond paste 0.5 μm The sharpness of the razor obtained by this polishing process was measured. The measuring equipment is as shown in Figure 4.
A nylon thread 7 is stretched between pulleys 6 provided at intervals of 20 cm, and weights 8 of 100 gr are attached to each end of the thread.
The razor blade 9 is lowered by a motor at a constant speed, and the position where the thread breaks is displayed as the distance mm from the thread level line. This distance is read on measure 10. The smaller this number is, the better the sharpness is. In addition, measurements were taken on 10 blades.
The average value was calculated. For comparison, measurements were also performed on zirconia molded by the casting method, fired and sharpened in the same manner as in the examples, and on commercially available stainless steel razor blades. 3rd result
Shown in the table. Judging from the results in Table 3, zirconia razor blades formed by fluid compression molding exhibit cutting values equivalent to commercially available stainless steel blades, while razor blades formed by casting molding exhibit sharpness values that are considerably inferior.

[Table] [Effects of the invention] According to the method of the present invention, the cutting quality is good, there is no rust,
In addition, since razor blades made of thin zirconia are mass-produced, it becomes possible to provide high-quality razor blades with excellent economic efficiency.

[Brief explanation of drawings]

1 to 3 show a longitudinal section of a mold used for fluid consolidation molding, and FIG. 4 is an explanatory diagram showing a schematic structure of a device for measuring the sharpness of a razor blade. 1... Upper inner cylinder, 2... Lower inner cylinder, 3... Clay, 4... Outer cylinder, 5... Pore, 6... Pulley, 7...
... Nylon thread, 8... Weight, 9... Razor blade, 10... Measure.

Claims (1)

[Scope of Claims] 1. A zirconia/liquid composite molding material is once placed in a fluid state and shaped into a razor blade shape in a state where liquid properties can be exhibited, and then the shaped body is shaped into a razor blade shape under a state where it cannot flow. A method for manufacturing razor blades, which comprises placing the razor blades in a state where they can exhibit solid properties by confining the razor blades, and then recompacting the blades to achieve homogenization, followed by demolding, firing, and sharpening. 2. The method for manufacturing a razor blade according to claim 1, characterized in that the cutting edge is polished into a single-sided polished blade or a double-sided polished blade. 3. A method for manufacturing a razor blade according to claim 2, characterized in that a coating is applied on and/or in the vicinity of the cutting edge.