Patent Application
20230141426
The present disclosure relates to a cutting implement such as a kitchen knife.
Traditionally, kitchen knives made of a material that contains a metal material as a main component have been used. Among these, in recent years, a kitchen knife made of stainless steel that contains nickel and chromium as a component is widely used (see Patent Document 1). Also known is a ceramic kitchen knife that contains zirconium oxide as a main component (see Patent Document 2).
In the present disclosure, a cutting implement includes a blade body. The blade body includes a base portion and a blade edge portion disposed along an end portion of the base portion. The base portion is made of a hollow body. The blade edge portion is made of a solid body. A reinforcing wall is provided inside the hollow body at at least a cutting implement tip portion of the base portion.
Hereinafter, a cutting implement according to an embodiment of the present disclosure will be described with reference to drawings. Note that the drawings used in the following description are schematic. The dimensions, proportions, and the like in the drawings do not necessarily coincide with the actual values.
As illustrated in
The shape and size of the blade body 2 are set in accordance with the applications of the cutting implement 1. If the cutting implement 1 is a kitchen knife, examples of the shape of the blade body 2 include shapes of a Japanese kitchen knife such as a kitchen knife for cutting fish, a santoku knife, and a sashimi knife, a Western knife such as a butcher knife, or a Chinese knife. If the cutting implement 1 is for applications other than a kitchen knife, such as a knife for a surgical instrument, the cutting implement 1 may have any shape as long as the shape is suited to its application.
The handle 3 connected to the blade body 2 is to be gripped by a hand when a person utilizes the cutting implement 1. As in the case of the blade body 2, the shape and size of the handle 3 are set in accordance with the applications of the cutting implement 1. The handle 3 contains wood, resin, ceramic, or a metal material.
The blade body 2 and the handle 3 may be formed integrally or separately. In the present embodiment, the blade body 2 and the handle 3 are separately formed. A part of the blade body 2, that is, a handle portion 23 is inserted into the handle 3, and is fixed to the handle 3 at the insertion portion. The handle portion 23 may also be referred to as a tang.
The cutting implement 1 may have any dimensions. For reference purposes, examples of the dimensions of the cutting implement 1 will be given. The total length Ht1 illustrated in
The thickness of the blade body 2 at the thickest portion may be set to not less than 1 mm and not more than 5 mm, for example. The length and thickness of the handle 3 can be set as appropriate. For example, the thickness of the handle 3 may be set to be not less than 5 mm and not more than 3 cm.
The base portion 21 of the blade body 2 is formed integrally with the handle portion 23. A hole 4 is provided in the handle portion 23. Only one hole 4 may be provided, or a plurality of holes 4 may be provided. The hole 4 is used for fixing the blade body 2 to the handle 3. As will be described later, however, the hole 4 also functions as a discharge hole for discharging powders within the cutting implement 1 during manufacturing of the cutting implement 1. The hole 4 is formed in a circular shape having a radius of not less than 0.5 mm and not more than 3 mm, for example. Note that the handle portion 23 may be used as a handle without the handle 3 being used.
As illustrated in
Note that in the following description, the base portion 21 includes the handle portion 23.
In the present disclosure, the blade edge portion 22 refers to a region of a solid body including a cutting edge ridge portion 22a. As illustrated in
As illustrated in
An end of the reinforcing wall 6 may be connected to the inner surface of a cutting implement tip 2a1, and need not be connected to the inner surface of the cutting implement tip 2a1.
As illustrated in
A plurality of vanes 61 orthogonal to the longitudinal direction of the reinforcing wall 6 are formed at predetermined intervals at the reinforcing wall 6 at the cutting implement tip portion 2a, and at the inner surfaces of the rear face portion 22b of the blade edge portion and the spine 21b of the base portion 21. The vane 61 is provided between the both side faces 21a and 21a as in the case of the reinforcing wall 6. The plurality of vanes 61 formed at the reinforcing wall 6 provide the cutting implement tip portion 2a with further improved reinforcing effect. The vane 61 is formed simultaneously with the reinforcing wall 6.
The hollow body that serves as the base portion 21 is formed by sintering or melting the first constituent material powder. The solid body that serves as the blade edge portion 22 is formed by sintering or melting the second constituent material powder.
For the first constituent material powder and the second constituent material powder, the same or different powder that is sinterable or meltable metal powder or ceramic material powder is used.
Examples of usable metal powder include ferritic stainless steel, austenitic stainless steel, nickel-based alloy such as Inconel (trade name), titanium alloy, nickel-cobalt alloy, cobalt alloy, cobalt-chromium-tungsten alloy such as Stellite (trade name), and cobalt-chromium-molybdenum alloy (CCM alloy). Examples of usable ceramic powder include oxide ceramics such as zirconium oxide (zirconia) or carbide ceramics such as tungsten carbide, titanium carbide, and vanadium carbide.
To integrally and firmly bond together the base portion 21 and the blade edge portion 22, the same material is preferably used for the first constituent material powder and the second constituent material powder. However, the first constituent material powder and the second constituent material powder may be different from each other as long as the base portion 21 and the blade edge portion 22 can be firmly bonded together.
The particle sizes of the first constituent material powder and the second constituent material powder can be determined as appropriate depending on the material or the like. Typically, the particle sizes of the first constituent material powder and the second constituent material powder are preferably not less than 40 μm and not more than 120 μm. For example, the particle sizes can be adjusted by a mechanical method such as ball milling and sifting through sieves, or a spraying method such as a gas atomizing method or a water atomizing method.
A method for manufacturing the cutting implement of the present disclosure will be described. To sinter the first constituent material powder to form a hollow body and to sinter the second constituent material powder to form a solid body, a powder sintering and additive manufacturing method is preferably employed, for example. To that end, a powder sintering 3D printer can be used.
Examples of the powder sintering and additive manufacturing method include selective laser sintering (SLS) and direct metal laser sintering (DMLS). Apart from the above, selective laser melting (SLM), electron beam melting (EBM), laser engineered net shaping, laser metal deposition (LMD), and the like can also be employed.
Selective laser sintering is a method in which material powders are spread over a shaping stage, and the material powders are irradiated with a laser beam such as that of a carbon dioxide gas laser to perform shaping. Shaping is performed while the material powder adjusted to a predetermined particle size is supplied from a powder supply unit onto the shaping stage. Upon completion of the shaping of one layer, the shaping stage is lowered by one step before the shaping of the next layer is started. In this manner, in the selective laser sintering, a target object is shaped in a powder-like material irradiated with a laser beam. According to the selective laser sintering, material properties (such as strength, hardness, toughness, and abrasion resistance) nearly equal to the material properties that the used material powder inherently possesses can be realized.
For the material powder used in the selective laser sintering, a metal powder and a ceramic material powder are commonly used. The metal powder is coated with water-soluble resin such as polyvinyl alcohol (PVA) to reduce or minimize oxidation of the material.
Direct metal laser sintering is different from selective laser sintering in which a carbon dioxide gas laser is mainly used in that an ytterbium laser is used. The ytterbium laser has advantages in that it has excellent output stability and it can stably maintain the same size. For the material powder, an uncoated metal powder made of a single material and a ceramic material powder are used.
Selective laser melting is the same as the selective laser sintering and the direct metal laser sintering in that irradiation with a laser beam is performed. In the selective laser melting, however, instead of being sintered, the material powder (a metal powder or a ceramic material powder) is melted and solidified to fabricate a shaped object. For the material, a metal powder that is the same as or similar to those described above is used. In performing shaping, Standard Triangulated Language (STL)-based 3D computer-aided design (CAD) data is cut into slices, and each layer is irradiated with a laser beam. An operation is repeated in which, upon solidification of one layer, the one layer is overlaid with metal powders that will serve as the next layer in the powder bed, and then the next layer is irradiated with a laser to be solidified. For the laser, as in the case of the direct metal sintering, a high-power ytterbium laser or the like is used. However, a higher power is obtained than in the direct metal sintering.
Electron beam melting is an additive method with an electron beam. The electron beam melting is a mechanism in which a metal powder is irradiated with an electron beam to be melted as in the case of the selective laser sintering. An electron beam emitted in high vacuum has a higher power and a higher speed than a laser beam, and this allows a precision metal part to be three-dimensionally printed accurately. Specifically, in the electron beam melting (EBM), the entire metal powder is heated to a constant temperature in producing a vacuum, and then the portion to be shaped is irradiated with an electron beam for high melting points. Here, an electron beam refers to a beam that is obtained by heating a filament in high vacuum and emitted by controlling emitted electrons with an electromagnetic coil. A ceramic material powder can also be used for the electron beam melting.
Unlike mechanisms in which a metal powder is irradiated with a laser, laser engineered net shaping is a method in which a metal powder is dropped from a nozzle into a molten pool, and then is sintered with a laser so that a layered body is formed. This method has advantages in that it allows smooth processing, provides a faster shaping speed, and can reduce the material cost to about half. A ceramic material powder can also be used for the laser engineered net shaping.
A procedure for fabricating the blade body 2 of the cutting implement 1 using a 3D printer will be described. First, 3D data that serves as an engineering drawing of the blade body 2 of the cutting implement 1 is prepared. Accordingly, 3D CAD software is utilized to perform modeling. For the 3D CAD software, a variety of commercially available products can be employed, and the 3D CAD software is not limited to a specific software.
In the present disclosure, 3D data are prepared for the base portion 21 that is a hollow body and the blade edge portion 22 that is a solid body, respectively. At this time, topology optimization software can also be used.
The 3D data created with 3D CAD software is converted into the 3D data format of the STL format. After the physical integrity of the STL data is checked in an STL verification tool, the target STL data is converted into actual data for the 3D printer to control the output. That is, the 3D data is cut into slices on a layer-by-layer basis, which are then converted into shaping tool path data (such as a G Code) for causing the 3D printer to operate. Conversion software is commonly referred to as slicer software.
Upon conversion of the STL data into the shaping tool path data, the tool path data is loaded into the 3D printer, and then shaping with the 3D printer is started. At this time, a support is designed and/or thermal stress is calculated as necessary to optimize the molding condition as appropriate.
In the present disclosure, the base portion 21 is made of a hollow body, and the blade edge portion 22 is made of a solid body. Thus, preferably, any one of the base portion 21 and the blade edge portion 22 is first shaped by the 3D printer, and then a control condition is changed before the other one is shaped.
The blade edge portion 22 preferably has a higher hardness than that of the base portion 21. To that end, the laser irradiation condition needs to be adjusted as appropriate. For example, a titanium carbide powder having a particle size of about from 2 to 5 μm may be added to a titanium alloy powder by about 0.1 to 0.3 mass % to add heterogeneous nucleation site particles and thereby form fine equiaxed crystals. In the SLM, without preheating, the cooling rate may be increased to obtain fine crystals. According to the LMD, cooling is fast, and thus fine crystals tend to be obtained. In the EBM and LMD, since columnar crystals extend in a direction parallel to the layering direction in a case where the liquid phase is transformed to the solid phase in a direction parallel to a layering direction, columnar crystals are formed with respect to the extended columnar crystals in the same as and/or similar to manner described above in a direction different from the direction parallel to the layering direction by 90 degrees, and these steps are repeatedly performed to form a layered body so that crystals grown in different directions overlap with each other. This can provide improved hardness. Depending on the cooling condition, a dense organizational structure between a metal and a ceramic or carbon can be developed to achieve high toughness and high hardness. After shaping the blade body 2, the material powder within the blade body 2 is discharged from the hole 4 of the handle portion 23. Note that at the time of shaping the base portion 21, the reinforcing wall 6 is simultaneously shaped.
A high toughness blade body 2 of the cutting implement 1 can be fabricated by controlling the organization. For example, adjusting the laser irradiation condition allows an effect that is the same as or similar to the effect of quenching to be exerted to increase the toughness of the blade body 2.
For the bonding together of the blade edge portion 22 and the base portion 21, since both are formed consecutively in the same shaping step, no step of bonding both together is necessary. That is, the blade edge portion 22 and the base portion 21 are integrally shaped. This allows high strength to be obtained even at the site considered to be the bonding portion between both.
The blade edge portion 22 can be formed by polishing the blade body 2 fabricated in this manner. When polishing the blade body 2, an abrasive such as alumina, silicon carbide, or diamond is preferably used to polish the blade body 2 at a secondary bevel angle from 20 to 40°. After polishing, the handle 3 is attached to the handle portion 23 of the blade body 2.
The obtained cutting implement 1 is lightweight because the base portion 21 is a hollow body, has excellent strength because the blade edge portion 22 is a solid body, and provides high sharpness.
Embodiments of the cutting implement according to the present disclosure have been described above. However, the present disclosure is by no means limited to the embodiments described above, and various modifications and enhancements can be made. For example, in the embodiments described above, the base portion 21 including the handle portion 23 and the blade edge portion 22 are fabricated with a 3D printer. However, the blade edge portion 22 that is a solid body may be fabricated in a different method, and, with a 3D printer, the base portion 21 including the handle portion 23 may be fabricated with a 3D printer and then be bonded to the blade edge portion 22.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-049101 | Mar 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/009876 | 3/11/2021 | WO |
