JP5210285B2 - Local cooling method - Google Patents
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- JP5210285B2 JP5210285B2 JP2009249211A JP2009249211A JP5210285B2 JP 5210285 B2 JP5210285 B2 JP 5210285B2 JP 2009249211 A JP2009249211 A JP 2009249211A JP 2009249211 A JP2009249211 A JP 2009249211A JP 5210285 B2 JP5210285 B2 JP 5210285B2
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- 238000001816 cooling Methods 0.000 title claims description 65
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 41
- 239000002184 metal Substances 0.000 claims description 31
- 239000002245 particle Substances 0.000 claims description 26
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 14
- 239000001569 carbon dioxide Substances 0.000 claims description 14
- 235000011089 carbon dioxide Nutrition 0.000 claims description 13
- 238000005507 spraying Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 9
- 239000007921 spray Substances 0.000 description 8
- 239000010419 fine particle Substances 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 229920000742 Cotton Polymers 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 229920006327 polystyrene foam Polymers 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- 229910052580 B4C Inorganic materials 0.000 description 1
- 206010053759 Growth retardation Diseases 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
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Description
本発明は、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、疲労き裂を含む所定領域を冷却することにより、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるに十分な大きさの疲労き裂開口を生じさせることができるようにした、局部冷却方法に関するものである。 The present invention cools a predetermined region including a fatigue crack before introducing the paste containing particles for reducing the fatigue crack growth rate so as to suppress the progress of the fatigue crack of a metal member. The present invention relates to a local cooling method capable of generating a fatigue crack opening having a size large enough to allow the paste containing particles for crack growth rate reduction to enter.
金属の疲労に関し、疲労き裂面内にフレッティング酸化物等の異物が生じることで、ブリッジング効果（くさび効果と称される場合もある）によって疲労き裂進展速度が低下することが広く知られている。 With regard to metal fatigue, it is widely known that foreign matter such as fretting oxide is generated in the fatigue crack surface, and the fatigue crack growth rate is reduced by the bridging effect (sometimes called the wedge effect). It has been.
特開平５−５７５３２号公報（特許文献２）には、前記ブリッジング効果を発現させる方法として、機械・構造物の構成部材に発生したき裂の先端部に微粉を注入して、これをき裂先端部に目詰まりさせることを特徴とするき裂進展防止方法について記載されている。具体的には、鋼板の疲労き裂に対して粒径０．０５μｍの微細粒シリカをインク液と混ぜた液体を注入することにより、疲労き裂進展速度が１／１０程度に減速することが示されている。 In Japanese Patent Laid-Open No. 5-57532 (Patent Document 2), as a method of expressing the bridging effect, fine powder is injected into the tip of a crack generated in a structural member of a machine / structure, and this is removed. It describes a crack growth prevention method characterized by clogging the crack tip. Specifically, the fatigue crack growth rate can be reduced to about 1/10 by injecting a liquid obtained by mixing fine silica having a particle diameter of 0.05 μm with an ink liquid into a fatigue crack in a steel sheet. It is shown.
特許第３８０８８４６号公報（特許文献３）には、疲労き裂の進展抑制方法として、母材の硬度以上の硬度を有する粒径が２〜４０μｍの微粒子（金属又はセラミックス等の微粒子）と粘性を有する油とが混合されたペーストを準備し、母材における疲労き裂の発生及び拡大が予め予想される個所の表面に前記子ペーストを塗布するようにした方法が示されている。この方法では、前記ペーストは、き裂の開閉に伴うポンプ作用やき裂先端の毛細管現象によって、開口したき裂内部に入り込む。そして、疲労き裂が開いた状態のときに前記ペーストが噛み込むことで疲労き裂の開口が抑制され、疲労き裂先端の応力変動が小さくなることにより、疲労き裂の進展速度を低下させて疲労寿命を延ばすことができるようにしている。 In Japanese Patent No. 3808844 (Patent Document 3), as a method for suppressing the progress of fatigue cracks, the viscosity of fine particles (fine particles of metal or ceramics) having a particle size of 2 to 40 μm having a hardness equal to or higher than the hardness of the base material is disclosed. A method is shown in which a paste mixed with an oil is prepared and the child paste is applied to the surface of a place where fatigue cracks in the base metal are expected to be generated and expanded in advance. In this method, the paste enters the open crack due to the pump action accompanying the opening and closing of the crack and the capillary action at the crack tip. And, when the fatigue crack is in an open state, the paste bites into it, thereby suppressing the opening of the fatigue crack and reducing the stress fluctuation at the tip of the fatigue crack, thereby reducing the fatigue crack growth rate. The fatigue life can be extended.
このように、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペースト（以下、単に微粒子ペーストともいう）を進入させる場合には、確実に微粒子ペーストによるき裂進展抑制効果を得るため、微粒子ペーストの塗布を行うに先立ち、微粒子ペーストを進入させるに十分な大きさの疲労き裂開口を生じさせておくことが重要となる。 As described above, when a paste containing particles for reducing the fatigue crack growth rate (hereinafter, also simply referred to as a fine particle paste) is introduced into a fatigue crack of a metal member in order to suppress the growth, it is ensured that the fine particle paste is used. In order to obtain the effect of suppressing crack propagation, it is important to generate a fatigue crack opening having a size sufficient to allow the fine particle paste to enter before the fine particle paste is applied.
この点に関連する技術として、従来、金属製部材のき裂を非破壊検査装置によって検出する技術分野において、前記き裂を顕在化させる局部冷却方法が提案されている（特開２００９−２７１３号公報（特許文献１））。 As a technique related to this point, a local cooling method for making the cracks apparent has been proposed in the technical field where a crack of a metal member is detected by a nondestructive inspection apparatus (Japanese Patent Laid-Open No. 2009-2713). Publication (Patent Document 1)).
この従来の局部冷却方法は、金属製部材のき裂の開口方向の応力を発生させ、この応力により前記き裂を開口させて顕在化させるべく、金属製部材のき裂を含む所定領域を中空の冷却領域限定部材で囲んだ後、その領域を冷却スプレーによって冷却するようにしている。 In this conventional local cooling method, a stress in the opening direction of a crack in a metal member is generated, and a predetermined region including the crack in the metal member is hollowed in order to open and manifest the crack by this stress. After being surrounded by the cooling region limiting member, the region is cooled by cooling spray.
前述した従来の局部冷却方法では、冷却源として市販の冷却スプレーを用いるようにしている。この市販の冷却スプレーは、内容物を気化された気体として噴射（噴霧）するものであって、該気体温度が−１５℃〜−２０℃程度あり、気体噴出時間も連続２分間程度である。また、発泡スチロール、木材などの断熱材からなる冷却領域限定部材で冷却領域を囲むようにしているが、その冷却領域限定部材内に気体を充填させても金属製部材との熱伝達効果が低く、熱伝達効果を高めるために金属製部材表面に冷却スプレーを近づけてしまうと、冷却スプレーの特性上、冷却範囲が狭くなってしまうという欠点がある。 In the conventional local cooling method described above, a commercially available cooling spray is used as a cooling source. This commercially available cooling spray injects (sprays) the contents as vaporized gas, the gas temperature is about -15 ° C to -20 ° C, and the gas ejection time is about 2 minutes continuously. Also, the cooling region is surrounded by a cooling region limiting member made of a heat insulating material such as polystyrene foam or wood, but even if gas is filled in the cooling region limiting member, the heat transfer effect with the metal member is low, and heat transfer If the cooling spray is brought close to the metal member surface in order to enhance the effect, there is a drawback that the cooling range becomes narrow due to the characteristics of the cooling spray.
このため、前記従来の局部冷却方法では、金属製部材のき裂をその検出が可能なレベルに顕在化させることは可能なものの、金属製部材の疲労き裂にその進展を抑制すべく微粒子ペーストを進入させるに十分な大きさの疲労き裂開口を生じさせることについては困難であり、従来、適当な方法がなかった。 For this reason, in the conventional local cooling method, although it is possible to make the crack of the metal member manifest to a level at which it can be detected, the fine particle paste is to suppress the progress of the fatigue crack of the metal member. It is difficult to generate a fatigue crack opening that is large enough to allow the material to enter, and there has conventionally been no suitable method.
そこで、本発明の課題は、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、疲労き裂を含む所定領域を冷却することにより、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるに十分な大きさの疲労き裂開口を確実に生じさせることができるようにした、局部冷却方法を提供することにある。 Accordingly, the object of the present invention is to cool a predetermined region including a fatigue crack prior to entering the particle containing paste for reducing the fatigue crack growth rate so as to suppress the progress of the fatigue crack of a metal member. Another object of the present invention is to provide a local cooling method capable of surely generating a fatigue crack opening having a size sufficient for allowing the particle containing paste for reducing the fatigue crack growth rate to enter.
前記の課題を解決するため、本願発明では、次の技術的手段を講じている。 In order to solve the above problems, the present invention takes the following technical means.
請求項１の発明は、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるための疲労き裂開口を生じさせる局部冷却方法であって、金属製部材の部材表面において疲労き裂を含む所定領域を、液化炭酸ガスによる綿状ドライアイスにより冷却することを特徴とする局部冷却方法である。 According to the first aspect of the present invention, prior to causing the fatigue crack growth rate reducing particle-containing paste to enter the fatigue crack of the metal member, the fatigue crack growth rate reducing particle-containing paste is entered. A local cooling method for generating a fatigue crack opening for causing a predetermined region including a fatigue crack on a member surface of a metal member to be cooled by cotton-like dry ice using liquefied carbon dioxide gas It is a cooling method.
請求項２の発明は、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるための疲労き裂開口を生じさせる局部冷却方法であって、金属製部材の部材表面において疲労き裂を含む所定領域を冷却領域限定用囲繞体で囲み、液化炭酸ガスボンベからの液化炭酸ガスを低温用ホースによって前記冷却領域限定用囲繞体内に導入して液体のまま噴射して、該冷却領域限定用囲繞体内に綿状ドライアイスを生成させ、該綿状ドライアイスにより前記所定領域を冷却することを特徴とする局部冷却方法である。 According to the second aspect of the present invention, prior to causing the fatigue crack growth rate lowering particle-containing paste to enter the fatigue crack of the metal member, the fatigue crack growth rate lowering particle-containing paste is entered. A local cooling method for generating a fatigue crack opening for enclosing a predetermined region including a fatigue crack on a surface of a metal member with a cooling region limiting enclosure, and liquefied carbon dioxide gas from a liquefied carbon dioxide gas cylinder It is introduced into the cooling area-limiting enclosure by a low-temperature hose and sprayed as a liquid to generate cotton-like dry ice in the cooling area-limiting enclosure, and the cotton-like dry ice cools the predetermined area. This is a local cooling method.
本発明の局部冷却方法は、金属製部材の疲労き裂にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、金属製部材の部材表面において疲労き裂を含む所定領域を、冷却スプレーとは違って、液化炭酸ガスによる綿状ドライアイス（綿菓子状ドライアイス）により冷却するようにしているので、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるに十分な大きさの疲労き裂開口を確実に生じさせることができる。 The local cooling method of the present invention includes a fatigue crack on the surface of the metal member before the particle containing paste for reducing the fatigue crack growth rate enters the fatigue crack of the metal member in order to suppress the progress. Unlike the cooling spray, the predetermined area is cooled by cotton-like dry ice (cotton candy-like dry ice) using liquefied carbon dioxide gas, so that the particle-containing paste for reducing the fatigue crack growth rate is allowed to enter. A sufficiently large fatigue crack opening can be reliably generated.
以下、図面を参照して本発明の実施形態について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
図１は本発明の局部冷却方法の手順を説明するための模式的説明図である。 FIG. 1 is a schematic explanatory view for explaining the procedure of the local cooling method of the present invention.
図１において、１は金属製部材である。この金属製部材１は、繰り返し荷重を受けて疲労き裂が発生しやすいクレーン，建設機械，橋梁等の機械，構造物の構成部材であり、図１（ａ）に示すように、金属製部材１の部材表面に疲労き裂２が発生している。
In FIG. 1, 1 is a metal member. This metal member 1 is a structural member of a machine or a structure such as a crane, a construction machine, a bridge, etc., which is susceptible to fatigue cracks due to repeated loads. As shown in FIG. The
まず、金属製部材１の部材表面において疲労き裂２を含む所定領域を冷却領域限定用囲繞体３で囲み、冷却範囲を限定する（図１（ｂ））。中空をなす冷却領域限定用囲繞体３は、この実施形態では箱体を伏せた形状をなし、ホース導入孔３ａが設けられた上面部と四周側面部とを有している。冷却領域限定用囲繞体３は、発泡スチロール，木材などの断熱材よりなっており、簡易なものである。
First, a predetermined region including the
次に、液化炭酸ガスボンベ４に一端側が接続された低温用ホース５の他端側を前記冷却領域限定用囲繞体３のホース導入孔３ａに挿し込み、低温用ホース５によって液化炭酸ガスボンベ４からの液化炭酸ガスを所定時間にわたって冷却領域限定用囲繞体３内に導入して液体のまま噴射することで、冷却領域限定用囲繞体３内に綿状（綿菓子状）のドライアイス（図示せず）を生成させる（図１（ｃ））。生成される綿状ドライアイスの温度は約−８０℃の低温である。液化炭酸ガスボンベ４は、業務用のもので、例えば容量５ｋｇのものである。
Next, the other end of the low temperature hose 5 connected at one end to the liquefied carbon dioxide cylinder 4 is inserted into the
そして、冷却領域限定用囲繞体３による金属製部材１表面の冷却領域が十分に冷却され、綿状ドライアイスと金属製部材１間で十分な熱伝達が行われて、例えば冷却領域表面温度が−４０℃まで冷却された段階で、金属製部材１表面より冷却領域限定用囲繞体３とともに綿状ドライアイスを除去する（図１（ｄ））。
And the cooling area | region of the metal member 1 surface by the
このように、本発明による局部冷却方法は、金属製部材１の疲労き裂２にその進展を抑制すべく疲労き裂進展速度低下用粒子含有ペーストを進入させるに先立ち、金属製部材１の部材表面において疲労き裂２を含む所定領域を、冷却スプレーとは違って、液化炭酸ガスによる綿状ドライアイスにより冷却するようにしているので、前記疲労き裂進展速度低下用粒子含有ペーストを進入させるに十分な大きさの疲労き裂開口を確実に生じさせることができる。後述の、本発明による局部冷却方法による効果を検証するための有限要素解析によれば、冷却に伴う応力によるき裂開口変位によって３６〜５２μｍの疲労き裂開口が得られており、これは疲労き裂進展速度低下用粒子含有ペーストを進入させるに十分な大きさのものである。
As described above, the local cooling method according to the present invention is the member of the metal member 1 prior to the particle containing paste for reducing the fatigue crack growth rate being entered into the
なお、疲労き裂進展速度低下用粒子と液体とを混合したペーストとしては、粒子には、その粒径が０．１〜１μｍであって、アルミナ、シリカ、ジルコニア、炭化ケイ素、炭化ホウ素及びダイヤモンドのうち１種以上を用いたものがよい。また、液体には、粘度が０．８Ｐａ・ｓ以下であって、揮発性が低い油がよく、特に難燃性の工業用油などがよい。 In addition, as a paste in which particles for reducing fatigue crack growth rate and a liquid are mixed, the particles have a particle size of 0.1 to 1 μm, and alumina, silica, zirconia, silicon carbide, boron carbide, and diamond. Of these, one using one or more of them is preferable. The liquid is preferably an oil having a viscosity of 0.8 Pa · s or less and low volatility, and particularly a flame-retardant industrial oil.
次に、本発明の局部冷却方法による効果を検証するための有限要素解析を実施したので、以下に説明する。有限要素解析は、伝熱解析によって局部冷却時の温度分布を算出し、しかる後、その温度分布をもとに熱変形解析を実施して得られる疲労き裂開口の値を求めた。 Next, since the finite element analysis for verifying the effect by the local cooling method of this invention was implemented, it demonstrates below. In the finite element analysis, the temperature distribution during local cooling was calculated by heat transfer analysis, and then the value of the fatigue crack opening obtained by conducting thermal deformation analysis based on the temperature distribution was obtained.
解析モデルは、薄肉部材（板厚９ｍｍの鋼板部材（図２でｔ＝９ｍｍ））を模擬したＳＨＥＬＬ要素による薄肉部材モデルと、厚肉部材を模擬した平面ひずみ要素による厚肉部材モデルとの２ケースとした。前記薄肉部材モデルは骨組構造等を構成する鋼製の薄肉部材を想定したものであり、前記厚肉部材モデルは鋳鍛鋼品等を構成する鋼製の厚肉部材を想定したものである． The analysis model is a thin-walled member model using a SHELL element that simulates a thin-walled member (a steel plate member having a plate thickness of 9 mm (t = 9 mm in FIG. 2)) and a thick-walled member model using a plane strain element that simulates a thick-walled member. It was a case. The thin-walled member model assumes a steel thin-walled member constituting a frame structure or the like, and the thick-walled member model assumes a steel thick-walled member constituting a cast forged steel product or the like.
図２は本発明の局部冷却方法による効果を検証するための有限要素解析における解析モデルの説明図、図３は本発明の局部冷却方法による効果を検証するための有限要素解析における解析メッシュを示す図である。 FIG. 2 is an explanatory diagram of an analysis model in finite element analysis for verifying the effect of the local cooling method of the present invention, and FIG. 3 shows an analysis mesh in finite element analysis for verifying the effect of the local cooling method of the present invention. FIG.
図２，図３に示すように、解析範囲は、薄肉部材モデル、厚肉部材モデルともにＬ１＝２００ｍｍ、Ｌ２＝６００ｍｍとし、周辺部分は無限要素としている。疲労き裂は、部材端面全長にわたって発生し（図２参照）、該部材端面から３０ｍｍの奥行き深さ（ａ＝３０ｍｍ）まで進展していると仮定し、き裂部要素の節点を共有せず切り離したモデルとしている。 As shown in FIGS. 2 and 3, the analysis range is L1 = 200 mm and L2 = 600 mm for both the thin member model and the thick member model, and the peripheral portion is an infinite element. A fatigue crack is generated over the entire length of the end face of the member (see FIG. 2), and is assumed to have progressed from the end face of the member to a depth of 30 mm (a = 30 mm), and does not share the joints of the crack element. The model is separated.
そして、前記の伝熱解析では、き裂周辺の幅ｂ＝１００ｍｍ、き裂深さ方向にｃ＝４０ｍｍの範囲を冷却領域（ｂ×ｃ）としてその温度を−４０℃、それ以外の部分の温度を２０℃（常温）と仮定し、温度分布を算出している。この温度は、本発明の局部冷却方法によって十分冷却可能な範囲である。 Then, in the heat transfer analysis, the temperature around −40 ° C. is set as the cooling region (b × c) in the range of width b = 100 mm around the crack and c = 40 mm in the crack depth direction. The temperature distribution is calculated on the assumption that the temperature is 20 ° C. (normal temperature). This temperature is in a range that can be sufficiently cooled by the local cooling method of the present invention.
有限要素解析に用いた材料物性値（機械的物性値及び熱的物性値）を表１に示す。 Table 1 shows material property values (mechanical property values and thermal property values) used in the finite element analysis.
図４は薄肉部材モデルでの伝熱解析で得られた温度分布を示す図、図５は厚肉部材モデルでの伝熱解析で得られた温度分布を示す図である。また、図６は薄肉部材モデルにおいて図４の温度分布になったときの熱変形解析の結果を示す図、図７は厚肉部材モデルにおいて図５の温度分布になったときの熱変形解析の結果を示す図である。 FIG. 4 is a diagram showing a temperature distribution obtained by heat transfer analysis using a thin member model, and FIG. 5 is a diagram showing a temperature distribution obtained by heat transfer analysis using a thick member model. 6 is a diagram showing the result of thermal deformation analysis when the temperature distribution of FIG. 4 is obtained in the thin member model, and FIG. 7 is the result of thermal deformation analysis when the temperature distribution of FIG. 5 is obtained in the thick member model. It is a figure which shows a result.
熱変形解析の結果によると、図６に示すように、前記薄肉部材モデルでは、局部冷却による疲労き裂開口は、き裂起点で約５２μｍであった。また、図７に示すように、前記厚肉部材モデルでは、局部冷却による疲労き裂開口は、き裂起点で約３６μｍであった。 According to the result of thermal deformation analysis, as shown in FIG. 6, in the thin-walled member model, the fatigue crack opening due to local cooling was about 52 μm at the crack starting point. As shown in FIG. 7, in the thick member model, the fatigue crack opening due to local cooling was about 36 μm at the crack starting point.
得られたこれらの大きさの疲労き裂開口は、前述した疲労き裂進展速度低下用粒子含有ペースト（粒子の粒径：０．１〜１μｍ、油の粘度：０．８Ｐａ・ｓ以下）を進入させるに十分な大きさであり、本発明の局部冷却方法とこの疲労き裂進展速度低下用粒子含有ペーストとを併用することにより、疲労き裂進展抑制効果を早期に発揮させることができる。 The obtained fatigue crack openings of these sizes are the above-described particle-containing paste for reducing the fatigue crack growth rate (particle diameter: 0.1 to 1 μm, oil viscosity: 0.8 Pa · s or less). It is large enough to enter, and the combined use of the local cooling method of the present invention and this particle-containing paste for reducing fatigue crack growth rate makes it possible to exhibit the fatigue crack growth suppression effect at an early stage.
１…金属製部材
２…疲労き裂
３…冷却領域限定用囲繞体
３ａ…ホース導入孔
４…液化炭酸ガスボンベ
５…低温用ホース
DESCRIPTION OF SYMBOLS 1 ...
Claims (2)
金属製部材の部材表面において疲労き裂を含む所定領域を、液化炭酸ガスによる綿状ドライアイスにより冷却することを特徴とする局部冷却方法。 Fatigue crack opening for allowing the fatigue crack growth rate lowering particle-containing paste to enter before the fatigue crack growth rate lowering particle-containing paste enters the fatigue crack of the metal member in order to suppress its progress A local cooling method for producing
The local cooling method characterized by cooling the predetermined area | region containing a fatigue crack in the member surface of metal members with the cotton-like dry ice by a liquefied carbon dioxide gas.
金属製部材の部材表面において疲労き裂を含む所定領域を冷却領域限定用囲繞体で囲み、液化炭酸ガスボンベからの液化炭酸ガスを低温用ホースによって前記冷却領域限定用囲繞体内に導入して液体のまま噴射して、該冷却領域限定用囲繞体内に綿状ドライアイスを生成させ、該綿状ドライアイスにより前記所定領域を冷却することを特徴とする局部冷却方法。 Fatigue crack opening for allowing the fatigue crack growth rate lowering particle-containing paste to enter before the fatigue crack growth rate lowering particle-containing paste enters the fatigue crack of the metal member in order to suppress its progress A local cooling method for producing
A predetermined region including a fatigue crack is surrounded by a cooling region limiting enclosure on the surface of the metal member, and liquefied carbon dioxide gas from a liquefied carbon dioxide cylinder is introduced into the cooling region limiting enclosure by a low temperature hose. A local cooling method, characterized by spraying as it is to generate cotton-shaped dry ice in the cooling area-limiting enclosure, and cooling the predetermined area with the cotton-shaped dry ice.
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