JP2713709B2

JP2713709B2 - Knife

Info

Publication number: JP2713709B2
Application number: JP62252187A
Authority: JP
Inventors: 滴水小村; 良二井上
Original assignee: Hitachi Metals Ltd
Current assignee: Hitachi Metals Ltd
Priority date: 1987-10-06
Filing date: 1987-10-06
Publication date: 1998-02-16
Anticipated expiration: 2013-02-16
Also published as: JPH0197592A

Description

【発明の詳細な説明】〔産業上の利用分野〕本発明は、布、紙、繊維等の切断に広く一般的に用い
られる刃物に関し、さらに詳しくはセラミックスからな
る刃先を有する刃物に関するものである。〔従来の技術〕従来、布、紙、繊維等の切断に用いられる刃物のほと
んどは、鋼製の刃物であった。ところが、年々、被切断
材の寸法精度、切り口のきれいさ等要求が大きくなり、
被切断材自体が難切断材化するに伴い、切味、耐久性共
に、より優れた刃物の要求が各分野で出てきている。現在では、刃物の材質としては、鋼に加えて超硬合
金、セラミックス等の硬さ、耐摩耗性に優れた材料が用
いられるようになってきた。特にジルコニア等のセラミ
ックスは、刃物材料として数多くの利点があることは、
今まで報告されている（特開昭58−71095号、特開昭59
−118395号等）。特開昭58−71095号は、正方晶ジルコニアを50モル％
以上含んだジルコニアを用いることにより、セラミック
スを刃物に応用可能とした技術であるが、セラミックス
製の刃物の場合には刃先の欠け（チッピング）が生じや
すく、単に刃物部材をジルコニアにしただけでは、刃先
の耐チッピング性、切味の両者と十分に満足できない。
また、特開昭59−118395号に示されるように、ジルコニ
アセラミックス刃物において、刃先角度θを20〜80゜に
規定してもかかる問題を完全になくすことはできない。ジルコニア系セラミックス以外、すなわち、より強
度、靭性の劣るセラミックスを刃物に応用した例として
特開昭59−108585号、特開昭61−79594号があるが、こ
れらは刃先に10〜80μｍの厚みをもたせ、耐チッピング
性、耐久性等を向上させようとするものであるが、刃先
が厚くなるために切味を犠牲にせざるを得ない欠点があ
る。刃先強度と切味の両者を向上させる技術としては、特
開昭59−502135号に示されるように、刃先近傍の刃厚を
厚くし、刃先より離れるに従って刃厚を薄くする技術が
あるが、刃先形状の検討だけではセラミックスの脆さを
十分カバーし、かつ切味の十分な刃物を提供するには不
十分である。〔発明が解決しようとする問題点〕上記のセラミックス製刃物は、脆いため、切味を向上
させると耐久性が低下するという問題点があった。すな
わち、切味を向上させるために、刃先を鋭利にすると、
チッピング等が生じやすく、また刃先強度を向上させる
ために、刃先角度を大きくすると切味が低下するという
問題点があり、セラミックスの持つ特性を十分活かすこ
とができなかった。本発明の目的は、刃先の性状に検討を加えることによ
り、切味、耐久性ともに優れたセラミックス製の刃物を
提供することである。〔問題点を解決するための手段〕第３図は、刃物の刃先部を模式的に表わした図であ
る。ここで、切刃を構成する主な要因としては、刃先角
度θ、刃面の面粗さＲ、刃先先端の幅Ｔ、刃先チッピン
グＡが挙げられる。本発明者らは、上記４つの要因が切味および耐久性に
及ぼす影響を調べるために、様々な検討を行なった結
果、第４図に示すように、刃先角度θは切断抵抗、すな
わち切味に大きく影響し、θ＝20゜付近で最も切断抵抗
が小さいことを見出した。これは、ジルコニアセラミッ
クスの刃物でナイロン糸を切断した時の値である。θ＝
10゜の場合、刃先は最も鋭利であるが、チッピングＡが
大きく、θ＝20゜の場合、５μｍ程度であるのに比べ、
θ＝10゜の場合、10μｍ程度のチッピングが生じ、また
刃先先端の幅Ｔも大きくなっているためである。チッピングＡに目すると、刃先角θが大きいほど、チ
ッピングサイズは小さくなるが、被切断材と刃面との摩
擦力が増加するため、切味が低下するのである。付に刃
面の粗さと切味、耐久性を検討した結果、第５図に示す
ように、面粗さが大きいほど切断抵抗が小さくなること
が判明した。しかしながら、面粗さＲが大きすぎると切
味がばらつき、また耐久性は低下する結果となった。こ
れは、面粗さＲを大きくするとチッピングＡのサイズ、
発生頻度が高くなり、また切刃先端の欠損単位が大きく
なり、刃先位置の幅Ｔが大きくなるためである。以上の結果をまとめたものが第１表である。第１表からわかるように、第３図に示す形状の刃物で
は切味、耐久性を共に向上させるための各要因を設定す
ることが非常に困難である。以上の問題点を解決すべく
検討を行なった結果、第１図に示すように、切刃先端近
傍と後方のそれぞれの刃面状態を独立に設定すれば良好
な切味、耐久性が得られることを見出した。すなわち、
本発明はセラミックスからなる刃物であって、該刃物の
刃先先端部分の刃先角をθ_１、最大表面粗さをR₁、該刃
先先端部分に連なる刃先後方部の刃面構成角をθ_２、最
大表面粗さをR₂とした場合、 θ_１＞θ₂,R₁＜R₂ の関係を満足することを特徴とする刃物である。すなわち、切刃先端近傍の刃面は、θ_１を大きくと
り、かつ面粗度R₁を小さくすることにより。耐久性、耐
チッピング性を向上させ、かつ後方の刃面のθ_２を小さ
くし、かつ面粗度R₂を大きくすることにより切味の低下
を妨げるものである。なお、θ_１、θ_２、R₁およびR₂は、第１図にそれぞれ
記載されているθ_１、θ_２、R₁およびR₂の該当箇所をい
うものであり、それぞれの絶対的な値はセラミックスの
材質、被切断物の材質等により適宜選択される。また、本発明の刃物は、ハサミ等の２枚の刃物の作用
による剪断力で切断する刃物についても、ナイフ等の１
枚の刃物により切断する刃物についても同様の効果があ
る。〔実施例〕次に実施例について説明する。第２図は、ジルコニア系セラミックスからなる刃物で
あり、プラスチック、合成繊維、布、紙等の切断に用い
られる。本発明の刃物を用いて、切断テストを行なった結果を
第２表に示す。第２図ａの丸刃で紙切断を行なった場合、本発明の刃
物は、切味も良好で、寿命も従来の標準的形状の刃物を
比較例とすると２倍以上となっている。しかも比較例の
刃物のように、使用中に被切断材の紙の切断面がケバ立
ったり、切断部近傍がしわになることがなくなった。第２図ｂの直刃で背広用の布地の切断を行なった場合
も同様に、比較例として挙げた従来形状の刃物の３倍以
上の寿命であった。第２図ｃの直刃でナイロンの釣糸を
切断した場合も同様で、切味が良好で初期チッピングの
ない状態で比較例の６倍程度の寿命となった。先に述べたように、θ_１、θ_２、R₁、R₂の最適条件
は、セラミックスの材質、被切断物の材質により異なる
が、 15゜≦θ_１≦90゜,5゜≦θ_２≦60゜ 0.05μｍ≦R₁≦１μm,0.8μｍ≦R₂≦3.5μｍの範囲が本発明の効果を顕著に示す。すなわち、θ_１が15゜未満では耐チッピング性、耐久
性に効果がなく、90゜を越えると切味低下が無視できな
くなり、θ_２は60゜を越えると被切断材と刃物との摩擦
力増加のため切味が低下する一方、５゜未満では第４図
に示すように切断抵抗が大きくなり切味が低下する。R₁
は0.05μｍ未満では切断抵抗が大きく切味が低下する一
方、１μｍを越えると耐チッピング性、耐久性の点で問
題となる。また、R₂は良好な切味を確保するために0.8
μｍ以上が必要であるが、3.5μｍを越えると切味がば
らつき耐久性を低下させる傾向になるからである。〔発明の効果〕本発明によれば、従来、相反する特性であった切味と
耐久性の両方を大幅に向上させた刃物の設計が可能とな
り、様々な切断において、長寿命で被切断材の切断状態
が良好な刃物を提供することができる。Description: TECHNICAL FIELD The present invention relates to a blade widely used for cutting cloth, paper, fiber and the like, and more particularly to a blade having a cutting edge made of ceramics. . [Prior Art] Conventionally, most of blades used for cutting cloth, paper, fiber and the like are steel blades. However, year by year, the requirements for the dimensional accuracy of the material to be cut, the cleanness of the cut edge, etc., have increased,
As the material to be cut itself becomes difficult to cut, there is a demand in various fields for blades having better sharpness and durability. At present, in addition to steel, materials having excellent hardness and wear resistance, such as cemented carbides and ceramics, have been used as materials for blades. In particular, ceramics such as zirconia have many advantages as blade materials.
It has been reported so far (JP-A-58-71095, JP-A-59-71095).
No. 118395). JP-A-58-71095 discloses that tetragonal zirconia contains 50 mol%
By using the zirconia included above, it is a technology that makes ceramics applicable to cutting tools, but in the case of ceramic cutting tools, chipping of the cutting edge is apt to occur, and simply using zirconia as the cutting tool member does not work. Both the chipping resistance and the sharpness of the cutting edge cannot be sufficiently satisfied.
Further, as disclosed in JP-A-59-118395, such a problem cannot be completely eliminated even if the cutting edge angle θ is set to 20 to 80 ° in zirconia ceramic cutting tools. Japanese Patent Application Laid-Open Nos. Sho 59-108585 and 61-79594, which apply ceramics other than zirconia-based ceramics, that is, ceramics having lower strength and toughness, to blades, have a thickness of 10 to 80 μm on the blade edge. This method is intended to improve the chipping resistance and durability, but has a disadvantage that the sharpness has to be sacrificed because the cutting edge becomes thick. As a technique for improving both the edge strength and sharpness, as shown in JP-A-59-502135, there is a technique of increasing the thickness of the blade near the edge and decreasing the thickness as the distance from the edge increases. Examination of the shape of the cutting edge alone is not enough to sufficiently cover the brittleness of ceramics and to provide a cutting tool with sufficient sharpness. [Problems to be Solved by the Invention] Since the above-mentioned ceramic blade is brittle, there is a problem that durability is reduced when sharpness is improved. In other words, when the cutting edge is sharpened to improve the sharpness,
Chipping and the like are apt to occur, and if the angle of the cutting edge is increased in order to improve the cutting edge strength, there is a problem that the sharpness is reduced, and the properties of ceramics cannot be fully utilized. An object of the present invention is to provide a ceramic cutting tool excellent in both sharpness and durability by examining the properties of the cutting edge. [Means for Solving the Problems] FIG. 3 is a diagram schematically showing a cutting edge of a blade. Here, the main factors constituting the cutting edge include the cutting edge angle θ, the surface roughness R of the cutting surface, the width T of the cutting edge, and the cutting edge A. The present inventors have conducted various studies in order to investigate the effects of the above four factors on sharpness and durability, and as a result, as shown in FIG. , And found that the cutting resistance was the smallest around θ = 20 °. This value is obtained when a nylon thread is cut with a zirconia ceramic blade. θ =
In the case of 10 °, the cutting edge is the sharpest, but the chipping A is large, and in the case of θ = 20 °, it is about 5 μm.
This is because, when θ = 10 °, chipping of about 10 μm occurs, and the width T of the tip of the cutting edge also increases. From the viewpoint of chipping A, as the cutting edge angle θ increases, the chipping size decreases, but the frictional force between the material to be cut and the blade surface increases, so that the sharpness decreases. In addition, as a result of examining the roughness, sharpness, and durability of the blade surface, it was found that the larger the surface roughness, the lower the cutting resistance, as shown in FIG. However, if the surface roughness R is too large, the sharpness varies, and the durability decreases. This is because when the surface roughness R is increased, the size of chipping A is increased.
This is because the frequency of occurrence increases, the number of missing units at the tip of the cutting edge increases, and the width T of the cutting edge position increases. Table 1 summarizes the above results. As can be seen from Table 1, it is very difficult to set each factor for improving both the sharpness and the durability with the blade having the shape shown in FIG. As a result of investigations to solve the above problems, as shown in FIG. 1, good cutting quality and durability can be obtained by independently setting the blade surface state near and behind the cutting edge. I found that. That is,
The present invention relates to a cutting edge made of ceramics, wherein the cutting edge angle at the tip end portion of the cutting edge is θ ₁ , the maximum surface roughness is R ₁ , and the cutting surface angle at the rear end portion of the cutting edge connected to the tip end portion is θ ₂ . If the maximum surface roughness was R _2, it is a tool which is characterized by satisfying the θ _1> θ _2, the R ₁ <R ₂ relationship. That is, the blade surface of the cutting edge near the tip takes a large theta _1, and by reducing the surface roughness R _1. Durability, in which to improve the chipping resistance, and to reduce the theta ₂ of the rear blade face, and prevents the deterioration of sharpness by increasing the surface roughness R _2. Note that θ ₁ , θ ₂ , R ₁ and R ₂ refer to the corresponding portions of θ ₁ , θ ₂ , R ₁ and R ₂ described in FIG. ₁ , respectively, and their absolute values Is appropriately selected depending on the material of the ceramic, the material of the object to be cut, and the like. The blade of the present invention can also be used for cutting with a shear force caused by the action of two blades such as scissors.
The same effect can be obtained for a blade that is cut by a single blade. Example Next, an example will be described. FIG. 2 shows a blade made of zirconia-based ceramics, which is used for cutting plastic, synthetic fiber, cloth, paper, and the like. Table 2 shows the results of a cutting test performed using the blade of the present invention. When the paper is cut with the round blade shown in FIG. 2A, the blade of the present invention has good sharpness and the life is more than twice as long as the conventional standard-shaped blade. Moreover, unlike the cutting tool of the comparative example, the cut surface of the paper of the material to be cut does not become burred during use, and the vicinity of the cut portion does not wrinkle. Similarly, the cutting of the suit fabric with the straight blade shown in FIG. 2B has a service life that is at least three times longer than that of the conventional-shaped blade as a comparative example. The same applies to the case where the nylon fishing line was cut by the straight blade shown in FIG. 2C. The life was about six times that of the comparative example in a state where the sharpness was good and there was no initial chipping. As described above, the optimum conditions of θ ₁ , θ ₂ , R ₁ , and R ₂ differ depending on the material of the ceramic and the material of the object to be cut, but 15 ° ≦ θ ₁ ≦ 90 °, 5 ° ≦ θ ₂ ≦ 60 ° 0.05 μm ≦ R ₁ ≦ 1 μm, 0.8 μm ≦ R ₂ ≦ 3.5 μm The effects of the present invention are remarkably exhibited. That, theta ₁ is chipping resistance is less than 15 °, no effect on durability, sharpness reduction exceeds 90 ° can not be ignored, theta ₂ is the frictional force between the workpiece and the tool and exceeds 60 ° On the other hand, if the angle is less than 5 °, the cutting resistance increases and the sharpness decreases as shown in FIG. R ₁
If it is less than 0.05 μm, the cutting resistance is large and the sharpness is reduced, while if it exceeds 1 μm, there is a problem in chipping resistance and durability. Also, R ₂ is 0.8 to ensure good sharpness
It is necessary to have a thickness of at least μm, but if it exceeds 3.5 μm, the sharpness varies and the durability tends to decrease. [Effects of the Invention] According to the present invention, it is possible to design a blade that has greatly improved both sharpness and durability, which have conventionally been contradictory characteristics. It is possible to provide a blade with a good cutting state.

【図面の簡単な説明】第１図は、本発明刃物の刃先部を示す斜視図、第２図は
実施例に用いた刃物の形状を示す図、第３図は従来の刃
物の刃先部を示す斜視図、第４図は刃先角と切断抵抗の
関係を示すグラフ、および第５図は刃面粗さと切断抵抗
の関係を示すグラフである。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a cutting edge portion of a blade of the present invention, FIG. 2 is a diagram showing a shape of a blade used in an embodiment, and FIG. FIG. 4 is a graph showing the relationship between the edge angle and the cutting resistance, and FIG. 5 is a graph showing the relationship between the blade surface roughness and the cutting resistance.

Claims

(57) [Claims] A cutting edge made of ceramics, wherein the cutting edge angle of the cutting edge of the cutting edge is θ ₁ , the maximum surface roughness is R ₁ , the cutting surface angle of the cutting edge rear portion connected to the cutting edge is θ ₂ , the maximum surface roughness the case of the _{_{_{R 2, θ 1> θ 2}}} , R 1 < tool which satisfies the relationship R ₂ is. 2. Θ ₁ , θ ₂ , R ₁ and
_2. The method according to claim ₁ , wherein the value of R2 satisfies 15 ° ≦ θ ₁ ≦ 90 °, 5 ° ≦ θ ₂ ≦ 60 ° 0.05 μm ≦ R ₁ ≦ 1 μm, 0.8 μm ≦ R ₂ ≦ 3.5 μm. Cutlery. 3. 3. The cutting tool according to claim 1, wherein the width of the tip of the cutting edge is 0.5 μm to 3.0 μm. 4. 4. The cutting tool according to claim 1, wherein the cutting tool cuts the object by shearing force generated by the action of the two cutting tools sliding on each other.
The knife according to any one of the above items. 5. The blade according to any one of claims 1 to 3, wherein the blade cuts an object by the action of one blade.