JP3622022B2 - Strength inspection method for members - Google Patents

Description

【００１７】
（ａ） 治具の熱膨張率が部材より大きい場合
（ｉ） 引張応力
部材が凹部及び／又は中空部を有する時には、治具を部材の凹部及び／又は中空部に所定のクリアランスで遊嵌し、治具、又は治具及び部材を加熱すると、部材に引張応力が発生する。
【００１８】
（ｉｉ）圧縮応力
治具が凹部及び／又は中空部を有する時には、部材を治具の凹部及び／又は中空部に遊嵌する。この場合、スタート時の温度で所定のクリアランスがある状態で、治具、又は治具及び部材を冷却すると、部材に圧縮応力が発生する。
【００１９】
（ｂ） 治具の熱膨張率が部材より小さい場合
（ｉ） 引張応力
部材が凹部及び／又は中空部を有する時には、治具を部材の凹部及び／又は中空部に遊嵌する。スタート時の温度で所定のクリアランスがある状態で、部材、又は治具及び部材を冷却すると、部材に引張応力が発生する。
【００２０】
（ｉｉ）圧縮応力
治具が凹部及び／又は中空部を有する時には、部材を治具の凹部及び／又は中空部に所定のクリアランスで遊嵌し、部材、又は部材及び治具を加熱すると、部材に圧縮応力が発生する。
【００２１】
引張応力及び圧縮応力のいずれの場合も、加熱した後遊嵌状態になるまで冷却する時には、内側にある治具又は部材を急冷するのが好ましい。具体的には、▲１▼内側にある治具の方が熱膨張率が大きい場合には、内側にある治具を急冷し、▲２▼内側にある部材の方が熱膨張率が大きい場合には、内側にある部材を急冷する。また、内側にある部材を急冷すると同時に、外側にある治具を加熱してもよい。このような場合に治具又は部材を徐冷すると、治具が部材に与える応力がなかなか小さくならず、部材の強度低下が起きるおそれがある。
【００２２】
また、冷却した後遊嵌状態になるまで昇温させる時には、外側にある治具又は部材を急加熱するのが好ましい。具体的には、▲１▼外側にある治具の方が熱膨張率が大きい場合には、外側にある治具を急加熱し、▲２▼外側にある部材の方が熱膨張率が大きい場合には、外側にある部材を急加熱する。また、外側にある部材又は治具を急加熱すると同時に、内側にある治具又は部材を冷却してもよい。このような場合に治具又は部材を徐々に昇温すると、治具が部材に与える応力がなかなか小さくならず、部材の強度低下が起きるおそれがある。
【００２３】
（６） 部材中のクラックの検出
加熱又は冷却の完了後部材を治具から分離し、部材内にクラックが発生したか否かを検出する。クラックの検出方法は公知のものでよいが、例として蛍光探傷法、Ｘ線透過探傷法等が挙げられる。
【００２４】
なお、工程（４） の加熱又は冷却を複数回繰り返し、部材の疲労検査を行うこともできる。
【００２５】
部材の中空部内に治具を遊嵌した一例を図１に示す。この例では、部材１は断面がエの字状で全体がドーナツ状になっている形状を有し、内方及び外方に突出するリング部１１、１２を有する。部材１より治具３の方が大きな熱膨張率を有する場合には、治具３、又は治具３及び部材１を加熱する。また部材１より治具３の方が小さな熱膨張率を有する場合には、両者を遊嵌し、部材１、又は部材１及び治具３を冷却する。
【００２６】
以下、窒化珪素系セラミックス製の部材１と、スチール製の治具３を使用する場合について、詳細に説明する。この場合には、治具３の方が部材１より大きな熱膨張率を有するので、治具３と部材１のリング部１１とのクリアランスを直径で７０±２μｍとして、室温で部材１に治具３を遊嵌する。遊嵌した状態で１１０ ℃の炉に入れ、部材１及び治具３が１１０ ℃になるまで保持する。炉から取り出した後、室温まで強制空冷又は水冷で急冷し、部材１から治具３を取り除く。次いで上記の方法でクラックの有無を検出する。
【００２７】
図２に示す実施例では、部材２は２つの突起部２１、２２を有する。２つの突起部２１、２２の間に棒状の治具５を遊嵌し、加熱又は冷却することにより、部材２の２つの突起部２１、２２の付け根部に引張応力を付与することができる。図３の実施例では、部材２は角の丸い筒状である。棒状治具５を部材２の四つの内面に所定のクリアランスをもって当接するように嵌挿する。図４の実施例では、棒状部材２を円筒状治具５の内面に所定のクリアランスをもって当接するように、治具５の中空部に遊嵌する。
【００２８】
本発明では、１つの治具で部材の一個所の強度検査を行うことができるが、１つの治具で部材の複数個所の強度検査を同時に行うこともできる。また１つの治具で複数の部材の強度検査を行うことができるし、複数の治具で１つの部材の強度検査を行うこともできる。
【００２９】
[2] 硬質部材の応力又は歪みの測定方法
本発明の硬質部材の応力又は歪みの測定方法は、以下の順序で行う。
(1) 前記硬質部材に応力又は歪みの測定手段を設け、
(2) 前記硬質部材と異なる熱膨張率を有する材質からなる治具と前記硬質部材との遊嵌の初期クリアランスを定め、
(3) 前記材質の治具及び前記硬質部材のいずれか一方を他方に遊嵌し、
(4) 測定開始温度から所定の温度まで前記治具及び／又は前記硬質部材を加熱又は冷却することにより、前記硬質部材に作用荷重を発生させ、
(5) 前記応力又は歪み測定手段を用いて、前記作用荷重から生じる応力又は歪みを測定し、
(6) 前記加熱後に前記治具又は前記硬質部材を急冷するか、前記冷却後に前記治具又は前記硬質部材を急加熱することにより遊嵌状態に戻す。
【００３０】
硬質部材の応力又は歪みの測定方法は基本的に上記［１］ に記載した方法と同じであるが、硬質部材に発生させる作用荷重は、治具と硬質部材との間のクリアランス及び治具の熱膨張率等を適宜選択することにより、任意に設定することができる。また、硬質部材の所定部位に設けられる応力又は歪みの測定手段として、歪みゲージ等の計測機器が挙げられる。本発明の硬質部材の応力又は歪みの測定方法を用いれば、硬質部材の破断強度等を測定することができる。
【００３１】
【実施例】
本発明を以下の実施例により詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
【００３２】
実施例１
Ｙ_２ Ｏ_３ 粉末（純度９９．９％、日本イットリウム（株）製）１．５ 〜５．０ 重量％と、Ａｌ_２ Ｏ_３ 粉末（ＳＡＦＦＩＬアルミナファイバー、ＩＣＩ社製）１．０ 〜５．０ ％と、Ｓｉ_３ Ｎ_４ 粉末（ＵＢＥ−ＳＮ−Ｅ０９、宇部興産（株）製）残部とからなる出発材料をスリップキャスティング法で成形し、１９００℃で焼結し、仕上げ加工を行って、図１に示す形状のセラミックリング１を作製した。セラミックリング１は内方及び外方に突出する一対のリング部１１、１２を有していた。セラミックリング１の特性及び寸法は以下の通りであった。
密度 ：３．２１ｇ／ｃｍ^３
熱膨張率：３．０ ×１０^−６Ｋ^−１
内径Ａ：１１９．０６０ ｍｍ、
内径Ｂ：１１９．０９０ ｍｍ、
内径Ｃ：１２５．０ ｍｍ、
外径Ｄ：１６１．０ ｍｍ
高さＨ：１７．５ ｍｍ
すみＲ： １．０ ｍｍ
リング部１１の肉厚Ｗ１：３．５ ｍｍ
リング部１２の肉厚Ｗ２：３．５ ｍｍ
リングの肉厚Ｔ：８．０ ｍｍ
【００３３】
また、リング部１１の肉厚にはばらつきがあり、標準肉厚３．５ｍｍ に対して、部分的に３．１ｍｍ のところがあり、なおその３．１ｍｍ の部分には、図６に示すような切欠きがある。
【００３４】
一方、高周波焼き入れを行った円柱状の炭素鋼Ｓ３５Ｃ製治具３（熱膨張率：１２×１０^−６Ｋ^−１、表面硬度Ｈ_Ｒ Ｃ：４０〜５５、高さ４５ ｍｍ 、直径 １１８．９９０ ｍｍ ）を準備した。治具３とリング部１１との初期クリアランスは７０μｍであり、リング部１２との初期クリアランスは１００ μｍであった。
【００３５】
リング１上で発生する歪みを測定するために、リング部１１の上面及び下面の内径Ａにできるだけ近い部位及びリング部１２の上面及び下面の内径Ｂにできるだけ近い部位に円周方向に歪みゲージ（ＺＦＬＡ−１及びＺＦＬＡ−６、東京測器研究所（株）製）を貼り付けた。
【００３６】
図１に示すように、セラミックリング１の中空部に治具３を挿入して治具台４上に置き、両者を電気炉で加熱した。加熱速度は約６℃／分であった。１１０ ℃まで加熱した後、すぐに電気炉から取り出し、主として治具３をエアブローで急冷して、セラミックリング１を治具から外した。この後、セラミックリング１を蛍光探傷法で検査し、クラックの有無を調べた。クラックが入ってなければ、セラミックリング１の強度を合格とし、クラックが入っていれば不合格とした。
【００３７】
１１０ ℃まで加熱したときのリング部１１及びリング部１２の歪み量を温度に対してプロットしたものを図５に示す。７５℃に加熱したときにリング部１１の内径が治具３に当接し、７５℃以上では、リング部１１の歪み量がほぼ直線的に増加した。一方、リング部１２は１００ ℃で治具に当接し、それ以後歪み量が直線的に増加した。また、リング部１１の肉厚には、ばらつきが有り、標準肉厚３．５ｍｍ に対して、部分的に３．１ｍｍ のところがある。この部分に歪みゲージを貼り付け、発生する歪み量を図５にプロットすると、薄肉であるため、発生する円周応力が標準肉厚３．５ｍｍ 部より大きくなった。１１０ ℃での各リング部の円周方向歪み量と円周応力をまとめて表１に示す。
【００３８】

【００３９】
本検査では、表１に示すようにリング１１の標準肉厚３．５ｍｍ に対して、肉厚３．１ｍｍ の薄い部分に発生する円周応力が高くなるが、本セラミックスリング１の実用中においても、同様な円周応力が発生する場合、肉厚の薄い部分により高い応力が発生する。
【００４０】
実施例２
実施例１と同じ方法でセラミックスリング１に対して再度強度検査を行った。リング部１１の肉厚３．１ｍｍ 部であり、図６及び７に示す切欠き６が存在する部分及びリング部１２（標準肉厚３．５ｍｍ ）の歪み量を温度に対してプロットしたグラフを図８に示す。
【００４１】
図８からわかるように、１１０ ℃までは実施例１の結果と±９μの誤差で再現性よくトレースする。 １２２．５℃に加熱したとき、リング１のうち、リング部１１の肉厚３．１ｍｍ 部であり、図６及び７に示す切欠き６が存在する部分の歪み量が４８１ μになり、この部分に１４６．７ＭＰａの円周応力が発生し、セラミックスリング１が破断した。リングにクラックが発生する時期は歪みゲージより検出する歪み量の急激な降下により検出可能である。また、破壊起点はリング部１１の高歪み発生箇所３１であり、リング１の破断強度は図７に示したリング１の高歪み発生個所３１に発生する応力により求められる。高歪み発生個所３１に発生する応力は、円周応力１４６．７ＭＰａに、有限要素法で求めた高歪み発生個所３１の応力集中係数α２．０ を乗じて２９３．４ＭＰａと得られる。よって、リング１の破断強度は２９３．４ＭＰａとなる。
【００４２】
このようにして、本発明の方法を用いてセラミックスの強度を測定することができる。また、この強度試験において高歪み発生個所３１に最大応力が発生したが、実機使用において同様な円周応力が発生する場合、同じように高歪み発生個所３１に応力が集中し、最大応力が発生する。
【００４３】
【発明の効果】
以上詳述した通り、本発明によれば、遊嵌自在の治具を用いて部材の強度検査を行うため、短時間で効率的な強度検査ができるとともに、実機での発生応力をほぼ再現できる。また発生する応力を容易に制御することができ、再現性も高い。さらに設備が簡単で安価に部材の強度検査及び応力、歪みの測定を行うことができる。このような本発明の部材の強度検査方法及び硬質部材の応力又は歪みの測定方法はセラミック部材を始めとしたあらゆる部材の強度検査に幅広く利用することができる。
【図面の簡単な説明】
【図１】本発明の一実施例による部材と治具とを遊嵌した状態の概略断面図である。
【図２】本発明の他の実施例による部材と治具とを遊嵌した状態の概略断面図である。
【図３】本発明のさらに他の実施例による部材と治具とを遊嵌した状態の概略断面図である。
【図４】本発明のさらに他の実施例による部材と治具とを遊嵌した状態の概略断面図である。
【図５】実施例１においてセラミックリングと金属治具とを遊嵌して測定した円周方向歪み量と温度との関係を示すグラフである。
【図６】図１に示すセラミックリングの部分横断面図である。
【図７】図１に示すセラミックリングの内部から見た部分側面図である。
【図８】実施例２においてセラミックリングと金属治具とを遊嵌して測定した円周方向歪み量と温度との関係を示すグラフである。
【図９】従来の方法による部材と治具とを遊嵌した状態の概略断面図（ａ）と平面図（ｂ）である。
【符号の説明】
１・・・セラミックリング
２・・・部材
３、５・・・治具
４・・・治具台
１１、１２・・・リング部
３１・・・高歪み発生個所
６・・・切欠き
９１・・・ゴム状弾性体
９２・・・圧力媒体
９３・・・半円環状治具[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting the strength of any member and a method for measuring the stress or strain of a hard member, and in particular, a member having a low material strength Weibull coefficient, a member whose defect rate needs to be as close to 0 as possible, or remarkably The present invention relates to a method for inspecting the strength of a member or the like that requires high reliability and a method for measuring stress or strain.
[0002]
[Prior art]
As a method for inspecting the strength of a member, a method of applying internal pressure, that is, a guarantee stress to a ceramic part through a liquid such as water or oil and a rubber-like elastic body with a hydraulic pump (Japanese Patent Laid-Open No. 4-256929), hydraulic pressure A method of applying internal pressure, that is, guaranteed stress, to a ceramic part through a liquid such as water or oil and an elastic tube with a pump (Japanese Patent Laid-Open No. 5-133842), and a ceramic product to a metal jig with a pressure device A method (Japanese Patent Laid-Open No. 4-350534) or the like for applying a guarantee stress to a ceramic component by heat elongation stress and friction by heating while pressing is disclosed.
[0003]
[Problems to be solved by the invention]
However, these methods have various problems. For example, in the methods of JP-A-4-256929 and JP-A-5-133842, a liquid pressure of at least 50 MPa level is applied via a liquid and a rubber-like elastic body. Shield material and rubbery elastic body mold allowance) are required. In addition, since the liquid may be scattered when the product is broken, it is necessary to cover the entire apparatus with a sealing box. Furthermore, in the case of the integrally formed product of the two-stage ring 1 shown in FIG. 9, when a pressure is simultaneously applied to the two-stage ring, a semi-annular jig 93 that is in close contact with the inside of the two-stage ring is further required. .
[0004]
In the method disclosed in Japanese Patent Laid-Open No. 4-350534, the thermal elongation stress of the metal jig is applied only to the end surface of the product by the coefficient of static friction μ between the ceramic product and the metal jig. Since μ = 0.3 to 0.4 and slip occurs between the ceramic product and the metal jig, it is necessary to apply a compressive load 2.5 to 3.3 times the radial load to be applied to the product. is there. In addition, since the thermal elongation stress is applied only to the end face of the product, it is impossible to generate a tensile stress almost uniformly in the axial direction on a long product, and even when stress is generated on a short product. It is necessary to apply a larger compressive load to the product. As a result, there is a concern that the strength of the product may be reduced, and the cost of the pressurizing apparatus required for that purpose may be increased.
[0005]
Accordingly, an object of the present invention is to measure the strength or stress of a hard member and to measure the stress or strain of a hard member that can freely apply compressive stress and tensile stress to any part of the member with a simple operation using an inexpensive apparatus. Is to provide a method.
[0006]
[Means for Solving the Problems]
As a result of diligent research in view of the above object, the present inventors have determined that when a jig is used to inspect the strength of a member, (a) one of the jig and the member is loosely fitted to the other. When determining the shape and selecting the material of the jig to have a different coefficient of thermal expansion from that of the member, engaging the jig and the member in a loose-fitting relationship, and heating or cooling, the difference in the coefficient of thermal expansion between the two from consuming a predetermined compressive or tensile stress member, it has with it testing the strength of the member, Rukoto can measure stress or strain of the rigid member, as well as (b) a jig after said heating or (rigid) member quenching Alternatively, it was discovered that if the jig or the (hard) member is heated rapidly after the cooling, the strength of the (hard) member can be prevented from being lowered, and the present invention has been conceived.
[0007]
That is, the member strength inspection method of the present invention in which the strength of the member is inspected using a jig is determined by (1) the stress necessary for the strength inspection of the member determined from the maximum stress generated in practical use, (2) From the strength inspection stress, a material of a jig having a coefficient of thermal expansion different from that of the member, and an initial clearance for loose fitting between the jig and the member are determined. (3) One of the jig of the material and the member (4) Stress is applied to the member by heating or cooling the jig and / or the member from an inspection start temperature to a predetermined temperature, and (5) the jig after the heating. Alternatively, the member is rapidly cooled, or the jig or the member is rapidly heated after the cooling to return to a loose-fitting state, and (6) detecting whether or not a crack has occurred in the member. .
[0008]
Further, the method for measuring the stress or strain of the hard member of the present invention comprises: (1) providing the hard member with stress or strain measuring means; and (2) a treatment made of a material having a thermal expansion coefficient different from that of the hard member. Determining an initial clearance of loose fitting between the tool and the hard member, (3) loosely fitting either the jig of the material or the hard member to the other, (4) from the measurement start temperature to a predetermined temperature By heating or cooling the jig and / or the member, an operating load is generated on the hard member. (5) Using the stress or strain measuring means, the stress or strain generated from the operating load is measured , Next, (6) the jig or the member is rapidly cooled after the heating, or the jig or the member is rapidly heated after the cooling to return to the loose fitting state .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
[1] Member Strength Inspection Method (1) Member The method of the present invention can be applied to any member strength inspection. For example, wood, polymer resin, metal and the like can be mentioned. In particular, there are materials whose Weibull coefficient of material strength is low, those where the defect rate needs to be as close to 0 as possible, or those where extremely high reliability is required, such as various ceramics, carbon, intermetallic compounds, etc. In particular, a hard brittle member made of a material having high hardness but low deformability or low plasticity is suitable. As the ceramic material, various strength materials such as silicon nitride, silicon carbide, alumina, and zirconia are suitable for the strength inspection method of the present invention.
[0010]
(2) Determination of the stress required to inspect the strength of the member The stress required to inspect the strength of the member is generally determined from the stress that the member receives during actual operation, particularly the maximum stress that is received during actual operation. . For example, (1) the stress that the member receives during actual operation is: (2) the Weibull coefficient of the material strength of the member, (3) the probability of defective products, and (4) the safety factor calculated from the strength reduction rate due to long-term fatigue. The multiplied value is the stress required for strength inspection. However, the stress necessary for the strength inspection can be determined by various methods without being limited to this method.
[0011]
(3) Determination of jig material, size and shape Strength inspection stress, thermal expansion coefficient of member, Young's modulus, Poisson's ratio, etc., jig material, initial clearance between member and jig, heating The heating temperature for generating stress and the cooling temperature for generating stress by cooling are determined. The jig is made of a material having a coefficient of thermal expansion different from that of the member to be inspected. Further, it is preferable that when the stress is generated due to the difference in coefficient of thermal expansion, the jig itself is not plastically deformed and fits within the elastic deformation region. As a material for such a jig, any material such as metal, ceramics, and polymer can be used according to the coefficient of thermal expansion of the member to be inspected.
[0012]
In general, the greater the difference in coefficient of thermal expansion between the jig and the member, the higher the stress. For this reason, the difference in coefficient of thermal expansion between the member and the jig is preferably 0.5 × 10 ⁻⁶ K ⁻¹ or more, and more preferably 5 × 10 ⁻⁶ K ⁻¹ or more.
[0013]
As the initial clearance between the member and the jig is smaller, a higher stress is obtained at a lower heating temperature or cooling temperature. However, if the initial clearance is too small, loose fitting between the jig and the member becomes difficult. The initial clearance between the member and the jig can be appropriately set based on conditions such as the shape and size of the jig and the member, the difference in coefficient of thermal expansion between the jig and the member, and the required stress. However, generally it is preferable to set it as 30-100 micrometers.
[0014]
(4) Manufacture of a jig and a jig based on the material and the initial clearance data determined to be loosely fitted. In the present invention, the shape of the jig may be determined so that the jig comes into contact with the test site of the member with the initial clearance and applies stress to the member evenly.
[0015]
(5) At the time of heating or cooling inspection of the jig and / or member, one of the jig and the member is loosely fitted to the other, and the member and / or the jig is heated or cooled to a predetermined temperature. Examples of the heating means include an electric furnace, an induction heating device, a hot air heater, and the like. Examples of the cooling means include an electric cooling device, a water-cooled spray, and an air-cooled jet. It is preferable to use the heating temperature within a range where the decrease in the elastic modulus of the jig due to the temperature is not large. When using a steel jig, a maximum of 300 ° C is preferred.
[0016]
Combinations when one of the jig and the member is loosely fitted to the other are as follows. Each case will be described.

[0017]
(A) When the coefficient of thermal expansion of the jig is larger than that of the member (i) When the tensile stress member has a recess and / or a hollow portion, the jig is loosely fitted into the recess and / or the hollow portion of the member with a predetermined clearance. When the jig or the jig and the member are heated, tensile stress is generated in the member.
[0018]
(Ii) When the compression stress jig has a concave portion and / or a hollow portion, the member is loosely fitted into the concave portion and / or the hollow portion of the jig. In this case, when the jig or the jig and the member are cooled in a state where there is a predetermined clearance at the temperature at the start, compressive stress is generated in the member.
[0019]
(B) When the coefficient of thermal expansion of the jig is smaller than that of the member (i) When the tensile stress member has a concave portion and / or a hollow portion, the jig is loosely fitted into the concave portion and / or the hollow portion of the member. When the member or the jig and the member are cooled in a state where there is a predetermined clearance at the temperature at the start, tensile stress is generated in the member.
[0020]
(Ii) When the compression stress jig has a recess and / or a hollow part, the member is loosely fitted into the recess and / or the hollow part of the jig with a predetermined clearance, and the member, or the member and the jig is heated, Compressive stress is generated.
[0021]
In both cases of tensile stress and compressive stress, it is preferable to rapidly cool the jig or member on the inside when cooling to a loose fit state after heating. Specifically, (1) If the inner jig has a higher coefficient of thermal expansion, quench the inner jig, and (2) the inner member has a higher coefficient of thermal expansion. First, the member inside is rapidly cooled. Moreover, you may heat the jig | tool in an outer side simultaneously with rapidly cooling the member in an inner side. In such a case, when the jig or the member is gradually cooled, the stress applied to the member by the jig is not easily reduced, and the strength of the member may be reduced.
[0022]
Further, when the temperature is raised to the loose-fitted state after cooling, it is preferable to rapidly heat the jig or member on the outside. Specifically, (1) when the outer jig has a larger coefficient of thermal expansion, the outer jig is rapidly heated, and (2) the outer member has a larger coefficient of thermal expansion. In some cases, the outer member is rapidly heated. Moreover, you may cool the jig | tool or member in an inner side simultaneously with rapidly heating the member or jig | tool in an outer side. In such a case, when the temperature of the jig or member is gradually increased, the stress applied to the member by the jig is not easily reduced, and the strength of the member may be reduced.
[0023]
(6) Detection of cracks in the member After completion of heating or cooling, the member is separated from the jig, and it is detected whether or not a crack has occurred in the member. The crack detection method may be a known one, but examples include a fluorescent flaw detection method and an X-ray transmission flaw detection method.
[0024]
In addition, the heating or cooling in the step (4) can be repeated a plurality of times to conduct a fatigue inspection of the member.
[0025]
An example in which a jig is loosely fitted in the hollow portion of the member is shown in FIG. In this example, the member 1 has a shape in which the cross section is an “E” shape and the whole is a donut shape, and includes ring portions 11 and 12 protruding inward and outward. When the jig 3 has a larger coefficient of thermal expansion than the member 1, the jig 3 or the jig 3 and the member 1 are heated. Further, when the jig 3 has a smaller coefficient of thermal expansion than the member 1, both are loosely fitted to cool the member 1 or the member 1 and the jig 3.
[0026]
Hereinafter, the case where the silicon nitride ceramic member 1 and the steel jig 3 are used will be described in detail. In this case, since the jig 3 has a larger coefficient of thermal expansion than the member 1, the clearance between the jig 3 and the ring portion 11 of the member 1 is set to 70 ± 2 μm in diameter, and the jig is attached to the member 1 at room temperature. 3 is loosely fitted. The loosely fitted state is placed in a furnace at 110 ° C. and held until the member 1 and the jig 3 reach 110 ° C. After removing from the furnace, the jig 3 is removed from the member 1 by rapid cooling to room temperature by forced air cooling or water cooling. Next, the presence or absence of cracks is detected by the above method.
[0027]
In the embodiment shown in FIG. 2, the member 2 has two protrusions 21 and 22. By loosely fitting the rod-shaped jig 5 between the two protrusions 21 and 22 and heating or cooling, a tensile stress can be applied to the bases of the two protrusions 21 and 22 of the member 2. In the embodiment of FIG. 3, the member 2 has a cylindrical shape with rounded corners. The rod-shaped jig 5 is inserted so as to contact the four inner surfaces of the member 2 with a predetermined clearance. In the embodiment of FIG. 4, the rod-like member 2 is loosely fitted in the hollow portion of the jig 5 so as to contact the inner surface of the cylindrical jig 5 with a predetermined clearance.
[0028]
In the present invention, the strength inspection of one part of the member can be performed with one jig, but the strength inspection of a plurality of parts of the member can be performed simultaneously with one jig. Further, the strength inspection of a plurality of members can be performed with one jig, and the strength inspection of one member can be performed with a plurality of jigs.
[0029]
[2] Method for Measuring Stress or Strain of Hard Member The method for measuring the stress or strain of the hard member of the present invention is performed in the following order.
(1) Provide a means for measuring stress or strain on the hard member,
(2) An initial clearance for loose fitting between the hard member and a jig made of a material having a different coefficient of thermal expansion from the hard member is determined,
(3) Either one of the jig of the material and the hard member is loosely fitted to the other,
(4) By heating or cooling the jig and / or the hard member from the measurement start temperature to a predetermined temperature, an acting load is generated on the hard member,
(5) Using the stress or strain measuring means, measure the stress or strain resulting from the applied load ,
(6) The jig or the hard member is rapidly cooled after the heating, or the jig or the hard member is rapidly heated after the cooling to return to the loose fitting state.
[0030]
The method for measuring the stress or strain of the hard member is basically the same as the method described in [1] above. However, the working load generated on the hard member depends on the clearance between the jig and the hard member and the jig. It can be arbitrarily set by appropriately selecting a coefficient of thermal expansion or the like. Further, as a stress or strain measuring means provided at a predetermined portion of the hard member, a measuring instrument such as a strain gauge can be cited. If the method for measuring stress or strain of a hard member of the present invention is used, the breaking strength of the hard member can be measured.
[0031]
【Example】
The present invention will be described in detail by the following examples, but the present invention is not limited to these examples.
[0032]
Example 1
Y ₂ O ₃ powder (purity 99.9%, manufactured by Nippon Yttrium Co., Ltd.) 1.5-5.0 wt%, Al ₂ O ₃ powder (SAFFIL alumina fiber, manufactured by ICI) 1.0-5. A starting material consisting of 0% and the remainder of Si ₃ N ₄ powder (UBE-SN-E09, Ube Industries, Ltd.) is formed by slip casting, sintered at 1900 ° C., and finished. A ceramic ring 1 having the shape shown in FIG. 1 was produced. The ceramic ring 1 had a pair of ring portions 11 and 12 protruding inward and outward. The characteristics and dimensions of the ceramic ring 1 were as follows.
Density: 3.21 g / cm ³
Thermal expansion coefficient: 3.0 × 10 ⁻⁶ K ⁻¹
Inner diameter A: 119.060 mm,
Inner diameter B: 119.090 mm,
Inner diameter C: 125.0 mm,
Outer diameter D: 161.0 mm
Height H: 17.5 mm
Corner R: 1.0 mm
Thickness W1 of the ring part 11: 3.5 mm
Wall thickness W2 of the ring part 12: 3.5 mm
Ring wall thickness T: 8.0 mm
[0033]
Further, the thickness of the ring portion 11 varies, and there is a portion of 3.1 mm with respect to the standard thickness of 3.5 mm, and the portion of 3.1 mm is as shown in FIG. There is a notch.
[0034]
On the other hand, a cylindrical carbon steel S35C steel jig was induction hardening 3 (thermal expansion coefficient: 12 × ¹⁰ -6 ^{K -1,} the surface hardness _H R C: 40 to 55, height 45 mm, diameter 118. 990 mm). The initial clearance between the jig 3 and the ring portion 11 was 70 μm, and the initial clearance with the ring portion 12 was 100 μm.
[0035]
In order to measure the strain generated on the ring 1, a strain gauge (circumferentially) is provided in a circumferential direction at a portion as close as possible to the inner diameter A of the upper surface and lower surface of the ring portion 11 and a portion as close as possible to the inner diameter B of the upper surface and lower surface of the ring portion 12 ZFLA-1 and ZFLA-6, manufactured by Tokyo Sokki Kenkyujo Co., Ltd.) were attached.
[0036]
As shown in FIG. 1, the jig | tool 3 was inserted in the hollow part of the ceramic ring 1, and it set | placed on the jig | tool base 4, and both were heated with the electric furnace. The heating rate was about 6 ° C./min. After heating to 110 ° C., the ceramic ring 1 was immediately removed from the electric furnace, and the jig 3 was mainly quenched by air blow to remove the ceramic ring 1 from the jig. Thereafter, the ceramic ring 1 was inspected by a fluorescent flaw detection method to check for cracks. If there was no crack, the strength of the ceramic ring 1 was accepted, and if there was a crack, it was rejected.
[0037]
FIG. 5 shows a plot of the amount of strain of the ring portion 11 and the ring portion 12 when heated to 110 ° C. versus temperature. When heated to 75 ° C., the inner diameter of the ring portion 11 abuts against the jig 3, and at 75 ° C. or higher, the amount of distortion of the ring portion 11 increased substantially linearly. On the other hand, the ring portion 12 contacted the jig at 100 ° C., and thereafter, the amount of strain increased linearly. Further, the thickness of the ring portion 11 varies, and there is a portion of 3.1 mm with respect to the standard thickness of 3.5 mm. When a strain gauge is attached to this portion and the amount of strain generated is plotted in FIG. 5, since it is thin, the generated circumferential stress is larger than the standard thickness of 3.5 mm. Table 1 summarizes the amount of circumferential strain and the circumferential stress of each ring portion at 110 ° C.
[0038]

[0039]
In this inspection, as shown in Table 1, the circumferential stress generated in the thin portion of the thickness of 3.1 mm is higher than the standard thickness of 3.5 mm of the ring 11. However, when a similar circumferential stress is generated, a high stress is generated in a thin portion.
[0040]
Example 2
The strength test was performed again on the ceramic ring 1 in the same manner as in Example 1. FIG. 6 is a graph in which the thickness of the ring portion 11 is 3.1 mm and the strain amount of the ring portion 12 (standard thickness 3.5 mm) shown in FIGS. 6 and 7 is plotted against the temperature. As shown in FIG.
[0041]
As can be seen from FIG. 8, tracing is performed with good reproducibility up to 110 ° C. with the result of Example 1 and an error of ± 9 μm. When heated to 122.5 ° C., the thickness of the ring portion 11 of the ring 1 is 3.1 mm, and the distortion amount of the portion where the notch 6 shown in FIGS. 6 and 7 is present is 481 μm. A circumferential stress of 146.7 MPa was generated in the portion, and the ceramic ring 1 was broken. The time when a ring is cracked can be detected by a sharp drop in the amount of strain detected by a strain gauge. Further, the fracture starting point is a high strain occurrence location 31 of the ring portion 11, and the breaking strength of the ring 1 is obtained by the stress generated at the high strain occurrence location 31 of the ring 1 shown in FIG. The stress generated at the high strain generation location 31 is obtained as 293.4 MPa by multiplying the circumferential stress 146.7 MPa by the stress concentration factor α2.0 of the high strain generation location 31 obtained by the finite element method. Therefore, the breaking strength of the ring 1 is 293.4 MPa.
[0042]
In this way, the strength of the ceramic can be measured using the method of the present invention. Further, in this strength test, the maximum stress is generated at the high strain occurrence location 31. However, when the same circumferential stress is generated when the actual machine is used, the stress is similarly concentrated at the high strain occurrence location 31 and the maximum stress is generated. To do.
[0043]
【The invention's effect】
As described above in detail, according to the present invention, since the strength inspection of a member is performed using a freely-fitting jig, an efficient strength inspection can be performed in a short time, and the generated stress in an actual machine can be substantially reproduced. . Moreover, the generated stress can be easily controlled, and the reproducibility is high. Furthermore, the equipment is simple and inexpensive, and the strength inspection of the member and the measurement of stress and strain can be performed. Such a strength inspection method for members and a method for measuring stress or strain of a hard member according to the present invention can be widely used for strength inspection of all members including ceramic members.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a state in which a member and a jig according to an embodiment of the present invention are loosely fitted.
FIG. 2 is a schematic cross-sectional view of a state in which a member and a jig according to another embodiment of the present invention are loosely fitted.
FIG. 3 is a schematic cross-sectional view of a state in which a member and a jig according to still another embodiment of the present invention are loosely fitted.
FIG. 4 is a schematic cross-sectional view of a state in which a member and a jig according to still another embodiment of the present invention are loosely fitted.
5 is a graph showing the relationship between the amount of strain in the circumferential direction and the temperature measured by loosely fitting a ceramic ring and a metal jig in Example 1. FIG.
6 is a partial cross-sectional view of the ceramic ring shown in FIG.
7 is a partial side view seen from the inside of the ceramic ring shown in FIG. 1. FIG.
8 is a graph showing the relationship between the amount of strain in the circumferential direction and the temperature measured by loosely fitting a ceramic ring and a metal jig in Example 2. FIG.
9A and 9B are a schematic cross-sectional view (a) and a plan view (b) of a state in which a member and a jig are loosely fitted by a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ceramic ring 2 ... Member 3, 5 ... Jig 4 ... Jig stand 11, 12 ... Ring part 31 ... High distortion generating part 6 ... Notch 91- ..Rubber elastic body 92 ... Pressure medium 93 ... Semi-annular jig

Claims (13)

It is a method for inspecting the strength of a member using a jig, and (1) the stress necessary for the strength inspection of the member is determined from the maximum stress generated in practical use, and (2) from the strength inspection stress, Determine the material of the jig having a different coefficient of thermal expansion from the member, and the initial clearance of loose fitting between the jig and the member, and (3) loosely fit one of the jig and the member to the other. (4) Stress is applied to the member by heating or cooling the jig and / or the member from an inspection start temperature to a predetermined temperature, and (5) the jig or the member is rapidly cooled after the heating. Alternatively, after the cooling, the jig or the member is rapidly heated to return to a loose fitting state, and (6) it is detected whether or not a crack has occurred in the member. The method for inspecting strength of a member according to claim 1, wherein the steps (4) to (6) are repeated. 3. The strength inspection method for a member according to claim 1, wherein a difference in coefficient of thermal expansion between the member and the jig is 0.5 × 10 ⁻⁶ K ⁻¹ or more, and high stress is generated. Method. The member strength inspection method according to any one of claims 1 to 3, wherein the member has a recess and / or a hollow portion, and a jig having a larger coefficient of thermal expansion than the member is used as the recess and / or the member. A method of loosely fitting in a hollow part, heating the jig or the jig and the member to give stress to the member, and then rapidly cooling the jig to return to the loose-fitted state . The strength inspection method for a member according to any one of claims 1 to 3, wherein the member has a recess and / or a hollow portion, and a jig having a thermal expansion coefficient smaller than that of the member is used as the recess and / or the member. A method of loosely fitting in a hollow portion, cooling the member or the jig and the member and applying stress to the member, and then rapidly heating the member to return to the loosely fitted state . The strength inspection method for a member according to any one of claims 1 to 3, wherein the jig has a recess and / or a hollow portion, and the member having a larger coefficient of thermal expansion than the jig is the recess of the jig. And / or loosely fitting in the hollow portion, heating the member or the jig and the member to give stress to the member, and then rapidly cooling the member to return to the loosely fitted state. . 4. The member strength inspection method according to claim 1, wherein the jig has a recess and / or a hollow portion, and the member having a smaller coefficient of thermal expansion than the jig is a recess of the jig. And / or loosely fitting into the hollow portion, cooling the jig or the jig and the member and applying stress to the member, and then rapidly heating the jig to return to the loose-fitted state. And how to. In the strength test method of member according to claim 1, wherein the member is Ri rigid member der made of ceramics, said jig method characterized by comprising the steel. The strength inspection method for a member according to any one of claims 1 to 8, wherein the initial clearance is 30 ~ 100 μ m A method characterized in that The strength inspection method for a member according to any one of claims 1 to 9, wherein an electric furnace, an induction heating device or a hot air heater is used as means for heating the member and / or jig, and the member and / or jig is heated. A method characterized in that an electric cooling device, a water-cooled spray or an air-cooled jet is used as means for cooling the tool. Claims 1 to Ten In the strength inspection method for a member according to any one of the above, the stress that the member receives during actual operation, (1) Weibull coefficient of material strength of member, (2) Defective product probability, and (3) A method wherein the strength inspection stress is a value obtained by multiplying a safety factor obtained from a rate of decrease in strength due to long-term fatigue. Claims 1 to Ten The member strength inspection method according to any one of the above, wherein a stress required for the strength inspection of the member is made smaller than the maximum stress. A method for measuring the stress or strain of a hard member, comprising: (1) providing the hard member with stress or strain measuring means; and (2) a jig made of a material having a coefficient of thermal expansion different from that of the hard member; Determining an initial clearance for loose fitting with the hard member; (3) loosely fitting either the jig of the material or the hard member to the other; and (4) the jig and the jig from the measurement start temperature to a predetermined temperature. / Or heating or cooling the hard member to generate an acting load on the hard member, and (5) using the stress or strain measuring means to measure the stress or strain resulting from the acting load , and then ( 6) The method wherein the jig or the hard member is rapidly cooled after the heating, or the jig or the hard member is returned to the loose-fitting state by rapidly heating after the cooling .

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