JP2004251428A - Manufacturing method for heat insulator - Google Patents

Manufacturing method for heat insulator Download PDF

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JP2004251428A
JP2004251428A JP2003045037A JP2003045037A JP2004251428A JP 2004251428 A JP2004251428 A JP 2004251428A JP 2003045037 A JP2003045037 A JP 2003045037A JP 2003045037 A JP2003045037 A JP 2003045037A JP 2004251428 A JP2004251428 A JP 2004251428A
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heat insulator
metal plates
heat
vacuum layer
metal
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Japanese (ja)
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Kazuya Miyake
一也 三宅
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Toshiba Home Technology Corp
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Toshiba Home Technology Corp
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Priority to JP2003045037A priority Critical patent/JP2004251428A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat insulator with a vacuum layer simply formed into a free shape, having high sealing reliability, even when bent, and superior heat insulating property and recycling property. <P>SOLUTION: A plurality of metal plates 1, 2 are superimposed on each other with their printed faces 3 as inner faces, non-printed faces 4, 5 between the metal plates 1, 2 are joined to each other by rolling, and a mouth portion 21 is provided in the printed face 3 in communication with outside air. Compressed air is filled through the mouth portion 21 to form an expanded sealed space 31 and then the mouth portion 21 is degassed to form the sealed space as the depressurized vacuum layer 15. The mouth portion 21 is blocked with e.g. soldering. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、保温機能および保冷機能を備えた各種機器に設けられる断熱体の製造方法に関する。
【０００２】
【従来の技術】
従来、保温機能を備えた電気ポット，炊飯器，保温ジャーなどの家電機器では、断熱性向上による省エネルギー性が重要な課題となっている。また、冷蔵庫，ワインクーラーなどの保冷機器では、保冷性を向上させることが省エネルギーのために必要となる。また、省エネルギーとしてではなく、外面温度を安全性のために下げる目的で、乾燥炉やボイラー，電気ヒータなどの機器においても、断熱性の向上は重要な要素である。こうした省エネルギーや断熱性向上の技術課題に関し、真空断熱が有効な手段の一つであることが知られている。
【０００３】
真空層を形成する手段は多々あるが、減圧真空環境中で、複数の金属板間の端部を密閉結合させて真空にするか、あるいは複数の金属板間に口部となる吸引孔を設け、吸引孔から真空ポンプなどで脱気するなどが一般的である。現在、電気ポットなどでは次の２つの方法が採用されている。
【０００４】
第１の方法は、断熱性を必要とする容器をステンレス製の真空容器にするもので、これは特許文献１などにおける金属製二重壁容器として知られている。この場合、製造に際しては、ステンレス製の内容器の外側に、所定の隙間を形成しつつステンレス製の外容器を向かい合わせ、内容器と外容器との端部を全周囲溶接した二重容器とすると共に、内部空間を減圧して真空にする。
【０００５】
また第２の方法は、例えば特許文献２などにおいて開示されるシリカ粉末を利用した断熱体である。これは具体的には、不織布などの袋の内部に低熱伝導のシリカ粉末などを入れて筐体を形成し、この袋をアルミ箔などの金属シート袋内に入れて、減圧室内でシート袋の端部を封孔し、内部のシリカ粉末間を真空に形成するものである。
【０００６】
【特許文献１】
特開平７−２２３０８９号公報
【特許文献２】
特開昭６２−１３９７９号公報
【０００７】
【発明が解決しようとする課題】
上記第１の方法は、真空容器としての強度を維持するために、材料厚さ（材厚）が０．５〜２．０ｍｍ以上のステンレス材を使用せざるを得ない。そのため、断熱体としての容器全体の重量が重い。また、内容器と外容器の端部全周囲を溶接しなければならず、加工工程が多くなる上に、溶接作業が伴なうので複雑な形状にすると製作が困難になる。さらに、内容器として耐食性の良いステンレス材を使用する関係で、外容器も溶接性を確保するためにステンレス材を使用しなければならないが、ステンレスはアルミニウムに比べて熱放射性が高く、保温時に外容器から熱が放散して断熱性が低下する要因になる。
【０００８】
また、内容器の内部をフッ素塗料などで塗装すると、塗装乾燥時に真空容器が高温に晒されて外容器にテンパーカラー（ステンレスの酸化皮膜）が発生し、さらに熱放射性が高くなる。加えて、ステンレス製でしかもその全周端部を全て溶接するため、大きな形状のものを製造することが重量や価格の点から困難になる。そのため、小型製品の断熱材としての実施に限定され、より大型の例えば冷蔵庫や乾燥炉などには実質的に採用できない。
【０００９】
一方、第２の方法は第１の方法に比べて、軽量なシート状断熱体を得ることができる反面、真空の筐体を保つために内部にシリカ粉末などを充填するので、このシリカ粉末の熱伝導により断熱性が悪化する問題がある。また、断熱体を曲げ加工すると、断熱体の外面部にあるアルミ箔が傷付きやすい上に、アルミ箔に形成される封孔は、アルミ箔自体が薄い材厚で溶接ができないため、加熱シールなどで行なわざるを得ず、結果的に封孔の信頼性が乏しい。そのため、こうした傷付き部や封孔部からのリークによって、内部の真空性が保持しにくくなる欠点を有する。
【００１０】
また、アルミ箔などの金属シート袋が、最終的な断熱体の外形形状となるため、矩形状以外に真空層ひいては断熱体の形状を自在に変えるのが困難である。さらに、加熱シールで封孔を行なう際に、内部の材質と外部の材質は異なっており、それぞれの材質の熱膨張率に違いが有るため、使用環境が高温になったりヒートサイクルがある加熱シール部や、熱膨張の内外差に起因して、隙間ができやすくなり、結果的に上述のリーク性が低下しやすくなる。しかも、筐体保持部材としてのシリカ粉末は、断熱体の廃棄時に金属と分別する必要があり、リサイクル性に劣る。
【００１１】
本発明は、上述した各問題点を解決しようとするものであり、真空層を自在な形状で簡単に加工して得ることができ、断熱性やリサイクル性にも優れた断熱体の製造方法を提供することを第１の目的とする。
【００１２】
本発明の第２の目的は、軽量で大型の機器にも容易に組み込むことができる断熱体の製造方法を提供することにある。
【００１３】
【課題を解決するための手段】
本発明の請求項１における断熱体の製造方法では、金属体に印刷部を適宜パターンに施すことによって、真空層を自在な形状に形成できる。そのため、断熱体を使用する機器に応じて、四角や丸などの定形パターン以外の任意で且つ複雑な形状に形成できる。また、断熱体の内部にはシリカ粉末などの保持部材が存在しないため、断熱体の廃棄時に内部を分解・分別する必要がなく、金属体を溶解すればリサイクルが容易である。
【００１４】
本発明の請求項２における断熱体の製造方法では、断熱体を使用する機器毎に、要求される断熱性能や断熱体の設置環境が異なるので、こうした断熱性能や設置環境に適した金属板の材料を、アルミニウム，ステンレス，チタンまたはその合金などから任意に選択することができる。例えば、高温多湿環境の場合には耐食性に優れたステンレスを選択し、軽量性が必要な場合にはチタンを選択する。また、被保温容器に接触させて使用せざるを得ない場合には、被保温容器と同じ材料のものを選択して電蝕を防止する。さらに、ステンレスはアルミニウムよりも熱伝導性が低いので、断熱体に熱伝導がある場合には、低熱伝導性のステンレスを選択する。また、断熱体を機器の外郭部材と兼用して使用する際も、強度や硬さが必要とされる場合は、ステンレスを選択する。さらに、金属アレルギーを防止するにはチタンを選択すればよい。
【００１５】
また、接合部が複数形成されていれば、接合部間の金属体間の梁強度によって、脱気減圧時に膨張させた金属体の非接合部における変形を抑制することができる。そのため、真空層の加工時に、一旦拡張させて形成した空間の容積を減少させてしまい、断熱性能を低下させる不具合を一掃できる。また、こうした変形を防止するのにわざわざ金属体を厚くすることもなく、断熱体全体の重量は増加しない。
【００１６】
本発明の請求項３における断熱体の製造方法では、実験結果に基づき、接合部間の距離を最適な所定倍数以内に選定しておけば、種々の形状の断熱体を新規設計する際にも、再度の検討をわざわざ行なうことなく、脱気減圧時に膨張させた金属体の変形を防止できる。これにより、断熱体の内部にシリカ粉末などの別の保持部材を介在させることなく、望ましい断熱性能を有する真空層を形成した軽量の断熱体を製造できる。
【００１７】
一方、真空層の断熱層を効率よく利用するには、金属体間での熱伝導を極力少なくすることが必要で、そのためには接合部の面積を小さくするのが好ましいが、逆にこの面積が少なすぎて、空気挿入時に接合部の剥離に伴なう金属体の破壊が生じると、真空層そのものが形成できなくなる致命的問題を生じる。そこで、実験結果に基づき、各接合部の面積を約５ｍｍ２以上とし、且つ接合部を曲線状に形成すれば、空気の注入時に接合部が剥離したり、金属体が破壊する不具合を確実に防止できる。
【００１８】
本発明の請求項４における断熱体の製造方法では、例えば電気ポットなどの機器の容器外側へ断熱体を巻加工して装着する場合は、真空層どうしや、真空層と端部とを重ねて断熱部の端部を処理すると、真空層がある分だけ重なり部の厚さが厚くなり、断熱体を収容する機器本体が大きくなる問題があるが、接合端部どうしを接触して断熱体を巻加工すれば、必要以上に断熱体が厚くならず、機器本体を必要以上に大きくしなくて済む。また、接触部に真空層が存在しないので、この接触部をリベットなどの止着具で固定し、筒状の断熱体を予め形成すれば、容器などへの装着性を改善できる。
【００１９】
本発明の請求項５における断熱体の製造方法では、金属体を平滑または光沢仕上げすることで、電磁波（赤外線）の反射性が向上するため、保温容器などからの熱放射を反射して、断熱体の熱吸収を抑制し、断熱体の断熱効果をより高めることができる。また、外観に断熱体が露出する場合にも外観性が向上する。
【００２０】
本発明の請求項６における断熱体の製造方法では、金属体に印刷部を適宜パターンに施すことによって、真空層を自在な形状に形成できる。そのため、断熱体を使用する機器に応じて、四角や丸などの定形パターン以外の任意で且つ複雑な形状に形成できる。また、断熱体の内部にはシリカ粉末などの保持部材が存在しないため、断熱体の廃棄時に内部を分解・分別する必要がなく、金属体を溶解すればリサイクルが容易である。
【００２１】
さらに、口部に金属板と同材料の筒体を溶接などで接合し、この筒体より圧縮空気を挿入して、印刷面に対応して非接合部となる箇所で、膨張した密閉空間を形成し、その後筒体より空気を抜いて密閉空間内を減圧して真空層を形成した後、筒体を溶接などで閉塞することで、所望の断熱体を得ることができる。そのため、共通する筒体により金属板間の内部拡張と密閉空間の減圧を兼用することができ、合理的で加工性を向上できる。
【００２２】
また、筒体の径を所定値以下または真空層の外厚の所定倍数以下とすることで、圧縮空気の注入や、金属体間の脱気減圧に支障がなくなると共に、筒体の開口面積を極力小さくすることで、端部開口部における溶接密閉加工が容易になる。さらに、機器の内部に断熱体を収容したときにも、この筒体の収容空間が極力少なくなって、機器の大型化を防ぎ、また筒体の収容空間に筒体を位置させるための曲げ加工や潰し加工なども支障なく行える。
【００２３】
さらに、筒体の径を真空層の内厚以上とすることにより、圧縮空気の注入や、金属板間の脱気減圧作業を円滑に行えると共に、筒体を金属体に挿入する際に金属体とのギャップが生じにくく、筒体を金属体に溶接などで簡単に接合できる。
【００２４】
本発明の請求項７における断熱体の製造方法では、金属体の表面に印刷面を適宜パターンに施すことによって、真空層を自在な形状に形成できる。そのため、断熱体を使用する機器に応じて、四角や丸などの定形パターン以外の任意で且つ複雑な形状に形成できる。また、断熱体の内部にはシリカ粉末などの保持部材が存在しないため、断熱体の廃棄時に内部を分解・分別する必要がなく、金属体を溶解すればリサイクルが容易である。
【００２５】
また、接合部の面積が約１２ｍｍ２で、接合部間を所定値以内とし、金属板を所定厚さに加工し、口部より気体を挿入し、金属体を含めた材厚が所定値となるように空間を形成すれば、金属体の内部を拡張する際に、母材である金属体の破壊を防止できると共に、真空層となる空間を確実に形成できる。
【００２６】
さらに、所定の真空度を有する真空層を形成すれば、真空層としての断熱性を確保できると共に、金属体の変形を防止でき、所定の真空容積を有し、しかも断熱性に優れた軽量の断熱体を製造することができる。
【００２７】
【発明の実施の形態】
以下、本発明における断熱体の製造方法に関する好ましい実施例について、添付図面を参照しながら説明する。図１〜図１２は、本発明の一実施例を示すもので、以下の説明は、断熱体の製造方法の手順を示す図１のフローチャートに沿って行なう。
【００２８】
圧延前の状態を示す図２において、１は断熱体の外郭部材となる金属板で、これはアルミニウム，ステンレス，チタン，あるいはこれらの金属の合金を主たる材料として形成される。またこの金属板１とは別に、主たる材料および材厚が同じで、断熱体の外郭部材となる金属板２が用意される（図３参照）。すなわち、ここでは断熱体の製造に際して、少なくとも２枚以上の金属板１，２を予め備えている。なお、以下の説明は、金属体である金属板１，２としてアルミニウム板を使用した例で行なうが、アルミニウム以外の同一材料で、または各々が異なる材料で各金属板１，２を形成してもよく、使用目的に応じて適宜最適な材料を選定すればよい。
【００２９】
断熱体の製造工程として、先ず図１に示すように、後述する所望の真空層パターンを形成するための印刷工程（ステップＳ１）が行なわれる。これは、材厚が２〜６ｍｍ程度のアルミニウム板からなる金属板１の片面に、カーボン，シリカ，アルミナ，チタニア，シリコーン，フッ素などの耐熱性を有する塗料を、所定の形状に例えばシルク印刷などで印刷する工程である。これにより、金属板１の片面には任意パターンの連続した印刷部たる印刷面３が形成される。この印刷を施した箇所は、最終的に真空層１５（図７参照）に対応したものとなるので、真空層１５を形成する形状に印刷面３をパターン印刷する。したがって、金属板１の周囲には印刷を施さず、そこに後で接合端部となる非印刷面４を形成する。また、接合端部４以外にも、印刷面３に囲まれた印刷を施していない非印刷部たる非印刷面５を、接合部として意図的に形成する。
【００３０】
上記ステップＳ１の印刷工程において、印刷に使用する塗料は、例えばカーボンや、シリカ，シリコーン，アルミナなどの微粉末を溶剤に混合してなり、この塗料を焼成することで溶剤が揮発し、図１に示すように、無機微粉末だけが印刷面３として所定のパターン状に残る。その際、シルクスクリーン印刷などで印刷面３を形成すれば、印刷パターンを任意に変えることで、最終的に得られる真空層１５を自在な形状にすることができる。なお、塗料の材料としては上記のものに限らず、要は耐熱性を有するものであればよい。
【００３１】
次のステップＳ２では、複数枚の金属板１，２を接触すなわち重ね合わせて例えば圧延する工程が行なわれる。この圧延工程では、図３に示すように、前記印刷面３を挟むようにして一対の金属板１，２を重ね合わせる。図３は、２枚の金属板１，２を重ね合わせた圧延前の状態を示しており、符号ｔは金属板１，２全体の材厚である。そして、この重ね合わせた２枚の金属板１，２を加熱させながら、図示しないローラ間に金属板１，２を加圧圧延して、金属板１，２全体の材厚ｔ’を１／４程度に減厚させる。図４は、圧延後における状態を示しているが、このときの金属板１，２全体の材厚ｔ’は圧延前の４分の１、すなわち１／４ｔとなっている。本実施例では、前述のように圧延前における個々の金属板１，２の材厚Ｔ（図２参照）が２〜６ｍｍであり、その全体材厚ｔは４〜１２ｍｍになるので、圧延後の複合材としての金属板１，２の全体材厚ｔ’は１／４ｔ＝１〜３ｍｍ程度となり、個々の金属板１，２の材厚Ｔ’は１／４Ｔ＝０．５〜１．５ｍｍ（図５参照）となる。
【００３２】
この加圧圧延により２枚の金属板１，２は、非印刷面４，５において同材料による分子間引力が作用して強力に結合するが、印刷面３を形成した箇所は、金属板２と印刷面３が異なる材質のため接合しない。すなわち加圧圧延後は、金属板１，２どうしが直接接触する非印刷面４，５により、それぞれ端部たる接合端部６と接合部７が形成されるのに対し、金属板２とこれに接触する印刷面３とにより非接合部８が形成され、前記接合端部６と接合部７とにより部分的に接合した複合体としての複合板９が得られる。
【００３３】
前述の印刷面３は、連続して繋がったパターンで形成されているが、金属板１の端部の一部に幅および長さが３〜３０ｍｍ程度の延長部１０が形成される。この延長部１０は、空気すなわち圧縮空気を挿入したり、脱気するのに利用する口部２１を形成するものである。なお、ステップＳ２の圧延加工後、複合板９の周囲を最終的な製品の外形形状に合わせて切断し、その切断時に印刷面３の一部を複合板９の端部に露出するようにしてもよい。図２には、製品の外形（圧延後の抜き外形）形状となる切断箇所Ｃが示されている。本実施例では、複合板９の切断後に延長部１０の先端が露出するように、この延長部１０を突出形成しているが、延長部１０を形成せず、切断時に印刷面３の一部を複合板９の端部に露出させてもよい。図５は、２枚の金属板１，２を圧延接合した後、複合板９を所望の形状に形抜き状態を示しているが、形抜きした後の複合板９の隅部は、角形状よりもむしろ曲面（Ｒ）形状が扱いやすく好ましい。
【００３４】
次のステップＳ３は、所望の通気口１１を作成する通気口作成工程で、これは日接合部８となる前記延長部１０を利用する。先ず、延長部１０に位置する複合板９の端部を、冶具（図示せず）を用いて拡張し、この拡張した口部２１（図７参照）に、金属板１，２と同材料の例えばアルミニウム製の金属パイプ２２を挿入した後、金属パイプ２２の基端を溶接により複合板９と接合して、口部２１と金属パイプ２２とにより通気口２３を形成する。接合後は図７に示すように、口部２１の内面と金属パイプ２２の基端側円周面に溶接部２４が設けられる。なお、通気口２３を閉塞する方法は溶接に限定されないが、溶接であれば従来の加熱シールに比べて隙間ができにくく、密閉の信頼性が高い。
【００３５】
次のステップＳ４は、複合板９内への圧縮空気の注入工程である。これは、通気口２３より少なくとも５Ｐａ以上１５０Ｐａ以下、好ましくは６０〜１２０Ｐａの範囲の圧力で、印刷面３により得られた複合板９内の非接合部８に圧縮空気を注入する工程で、通気口２３より圧縮空気を注入した直後の状態を図６に示す。圧縮空気の注入時には、複合板９の上面（一側面）および下面（他側面）に、それぞれ押え型２６，２７を配設し、必要以上に複合板９が膨張しないように規制する。また、上側の押え型２６と下側の押え型２７との隙間ｄは、好ましくは２〜６ｍｍ程度にする。こうして、圧縮空気が複合板９内の非接合部８に注入されると、この空気の圧力にアルミニウム製の金属板１，２が外方に押されて膨張する。そして、複合板９がある程度膨張すると、金属板１，２の外面が押え型２６，２７に当接して膨らみが規制され、所定の厚さ寸法で複合板９の内部に空気層となる空間としての密閉空間３１が形成される。
【００３６】
なお、前述のステップＳ３における金属パイプ２２の溶接接合は、金属板１，２を圧縮空気で拡張させた後に行なってもよい。この場合、延長部１０に位置する複合板９の端部を冶具で部分的に拡張し、この拡張した口部２１から圧縮空気の注入を直接行なう。
【００３７】
また、前記ステップＳ４の工程で、注入する圧縮空気の圧力が小さいと、複合板９内部が十分に拡張せず、また圧縮空気の圧力が高すぎると、接合端部６を含めた接合部７が剥離したり、母材である金属板１，２自体が破壊する可能性があるので、金属板１，２の材料や材厚を考慮して、圧力を選定する必要がある。因みに、Ａ１０５０系やＡ１１００系のような９９％以上の純度を有し、圧延前の材厚Ｔが約２ｍｍ（１．２〜２．８ｍｍが好ましい）のアルミニウム板を母材とした場合、ステップＳ２の圧延工程で４倍圧延を行なうと、母材単体の材厚は０．５ｍｍ（好ましい範囲では０．３〜０．７ｍｍ）となるが、ここで得られた複合板９を、その後のステップＳ４の圧縮空気注入工程で、全体材厚Ｄが４ｍｍ（好ましい範囲では２〜６ｍｍ）となるように、かつ密閉空間３１ひいては最終的な真空層１５の厚さＣが約３ｍｍとなるように拡張させた実験では、圧縮空気の注入圧力が１０Ｐａ未満であると、十分に複合板９の内部が拡張せず、逆に１３０Ｐａ以上になると、接合端部６や接合部７が剥離したり、母材である金属板１，２が破壊することが判明した。また、５０Ｐａ以下では、非接合部８の隅々にまで拡張させるのに多少時間が長く掛かり、作業性が劣化する。そのため、作業性が悪化せず、複合板９の内部を適正に膨らますことができるようにするには、圧縮空気の注入圧力を６０〜１２０Ｐａの範囲にするのが好ましい。
【００３８】
しかし、圧縮空気の注入圧力が適正な範囲であっても、圧延工程による接合端部６や接合部７の面積が小さいと、接合強度が弱くなる関係で、その後の圧縮空気の注入工程で、こうした接合端部６や接合部７が剥離したり、母材である金属板１，２が破壊する虞れがある。そこで、前述と同様にＡ１０５０系やＡ１１００系のような９９％以上の純度を有し、圧延前の材厚Ｔが約２ｍｍのアルミニウム板を母材として、母材単体の材厚Ｔ’が０．５ｍｍとなるように、圧延工程で４倍圧延を行なったサンプル品では、略円形の接合部７の直径φ＝２ｍｍ（面積Ｓ＝約３ｍｍ２）の場合に、上記剥離や破壊が発生し、直径φ＝２．５ｍｍ（面積Ｓ＝約４．９ｍｍ２）の場合に、剥離ぎみではあるものの破壊はなく、何とか使用できる状態となり、直径φ＝３ｍｍ（面積Ｓ＝約７ｍｍ２）の場合に、剥離や破壊が発生せず問題がないという結果が得られた。したがって、接合部７の面積Ｓは５ｍｍ２、好ましくは７ｍｍ２以上とすれば、圧縮空気の注入時に接合部７が剥離したり、金属板１，２が破壊する不具合を確実に防止できる。
【００３９】
さらに、断熱性を考慮して後述の真空層１５をできるだけ広く確保するためには、複合板９の外周に形成される接合端部６を可能な限り狭くしたいが、上述のような接合端部６からの剥離や、金属板１，２の破壊を確実に防止することも考慮すれば、少なくとも接合端部６の幅Ｗを、複合板９の全周囲に渡り２ｍｍ以上確保するのが好ましい。
【００４０】
これに関連して、各接合部７のパターン形状において、その外周に先鋭な角部があると、圧縮空気の注入時に接合部７の角部に圧力が集中し、接合部７が剥離したり、金属板１，２が破壊する懸念を生じる。そこで図８に示すように、圧縮空気が挿入される前の段階で、非印刷面５により形成された各接合部７の外周に少なくとも半径Ｒ＝１ｍｍ、好ましくは半径Ｒ＝２ｍｍ以上の角Ｒ部３６が形成されるようにして、各接合部７の外周を先鋭な角部のない曲線状にする。これにより、圧縮空気により複合板９の内部を拡張する際に、圧力を極力分散させること防いで、接合部７が剥離したり、金属板１，２が破壊する不具合を確実に防止できる。
【００４１】
同様に、複合板９の周囲にある接合端部６と、その内側にある非接合部８との境界部も全て先鋭な角部のない曲線状にする。そのために本実施例では、圧縮空気が挿入される前の段階で、非接合部８の外周に少なくとも半径Ｒ＝１ｍｍ、好ましくは半径Ｒ＝２ｍｍ以上の角Ｒ部３７が形成される。
【００４２】
次のステップＳ５は、真空層形成工程である。真空層形成工程終了直後の状態を、図７に示す。この工程では、複合板９の内部に形成された密閉空間３１を、通気口２３より真空ポンプ（図示せず）にて脱気減圧し、その後、金属パイプ２２の先端部をキャップして、さらに溶接やブレ−ジングにて封孔する。図７では、封孔の際の溶接部３８が、金属パイプ２２の端部開口部を閉塞している。こうして、複合板９間に所定の形状で約１Ｔｏｒｒ（１Ｔｏｒｒ＝１３３Ｐａ）程度、好ましくは１．５Ｔｏｒｒ〜Ｏ．１Ｔｏｒｒ（１９９．５〜１３．３Ｐａ）の真空度の真空層１５を形成する。または別な製造方法として、減圧室内に複合板９を置いて通気口２３を封孔し、内部が減圧した状態にして真空化を行なってもよい。真空層１５を形成した状態では、図７に示すように、真空層１５の厚さ（内厚）Ｃが約３ｍｍ、好ましくは１〜５ｍｍの範囲となり、かつ真空層１５を含めた全体材厚（外厚）Ｄが４ｍｍ、好ましくは２〜６ｍｍの範囲となる断熱に優れた複合板９が得られることになる。
【００４３】
内部に空気層である密閉空間３１を形成する金属板１，２は、上記ステップＳ４の工程で圧縮空気により押圧され延ばされているため、加工硬化して強度が強くなり、脱気減圧の際の変形防止効果を得ることができる。
【００４４】
ところで、圧延加工により接合部７を得るための非印刷面５は、所定間隔で複数個形成されると共に、圧縮空気の注入により金属板１，２を拡張した後の、接合部７間での金属板１，２の梁強度によって、前記ステップＳ５の真空層形成工程における内部減圧時に、膨張させた非接合部８（印刷面３）を取り囲む金属板１，２の箇所が、凹んでしまう変形を抑制するように形成される。
【００４５】
なお、圧延前の材厚Ｔが約２ｍｍ（１．２〜２．８ｍｍが好ましい）で、Ａ１０５０系またはＡ１１００系のアルミニウム板を母材の金属板１，２として使用し、圧延工程で４倍圧延（圧延後の母材単体の材厚Ｔ’は約０．５ｍｍになる）を行い、さらに圧縮空気にて複合板９の内部を拡張させた後の内部減圧実験の結果では、内部を１Ｔｏｒｒに減圧させた場合に、接合部７間の距離Ｌを５ｍｍ，８ｍｍ，１２ｍｍ（材厚Ｔ’の２４倍）としたときには、拡張した金属板１，２の凹みはなかった。一方、同じ条件で、接合部７間の距離Ｌを１５ｍｍ，１８ｍｍ，２３ｍｍ（材厚Ｔ’の４６倍）としたときには、拡張した金属板１，２にやや凹みが生じたが、真空層１５を形成可能な程度の凹みであった。さらに、接合部７間の距離Ｌを２７ｍｍ（材厚Ｔ’の５４倍），３０ｍｍにすると、拡張した金属板１，２の凹みが大きく、２枚の金属板１，２が接触してしまい、最終的な真空層１５の形成に難があった。以上の実験結果から、それぞれの接合部７間にある非接合部８の距離Ｌは、圧延後における属板１，２単体の材厚Ｔ’の５０倍以下（Ｌ≦Ｔ’×５０）、好ましくは２５倍以下（Ｌ≦Ｔ’×５０）とすることが望ましい。
【００４６】
次に、上記実施例に伴なう変形例を列記する。図７に示すように、真空層１５を含めた全体材厚Ｄは２〜６ｍｍ程度となるのが好ましいが、これは内部の減圧にて変形しない強度を有する厚さを選定すればよい。また、加圧圧延は１／４減厚で説明したが、圧延の程度は金属板１，２の接合強度などに応じて任意に選定すればよい。また、真空層１５の厚みは、材料の伸び（切れ防止）と断熱性、および使用機器の複合板９の要求厚さなどに応じて選定すればよい。
【００４７】
その他、真空層１５内部の真空度は約１Ｔｏｒｒで説明したが、これも使用する機器の要求される断熱性能に応じて適宜設定すればよい。
【００４８】
また、最終的な真空層１５の形状を決める印刷面３のパターン（模様形状）は、使用する機器の要求される断熱性能に応じて任意に設定すればよい。例えば、印刷面３のパターンに点状または線状などの非印刷面５を部分的に設け、これにより真空層１５内の内部減圧による変形防止用の接合部７を設けてもよい。但し、強度向上のために設けた真空層１５間の接合部７の面積が大きくなると、この接合部７による熱伝導により断熱効果が落ちるので、好ましくは極力少ない接合面積の方が、断熱性の点で都合がよい。
【００４９】
また、場合によっては、複合体である複合板９の表面を、アルマイトや塗装にて防錆処理してもよい。
【００５０】
ところで、前記ステップＳ３の通気口作成工程において、通気口２３を構成する金属パイプ２２の外径φ２が太くなると、金属板１，２間は金属パイプ２２の外径φ２以上に拡張させて金属パイプ２２を挿入させなければならないため、作業性が悪化するだけでなく、母材である金属板１，２が破壊する虞れがある。また、真空層１５の外厚Ｃより金属パイプ２２の外径φ２が太くなり過ぎると、機器の内部に断熱板である複合板９を装着したときに、金属パイプ２２を収容するのに大きな空間が必要となり、機器本体の大型化をまねいてしまう。そのため、金属パイプ２２は極力細い方が良いが、細すぎると圧縮空気の注入や真空ポンプによる減圧作業がしにくくなる問題がある。そこで、金属パイプ２２の外径φ２に関し検討した結果、金属板１，２を含めた真空層１５の外厚Ｄが４ｍｍの場合は、外径φ２が５〜９ｍｍの範囲が最も作業性が良く、外径φ２が５ｍｍ未満では、圧縮空気の注入や減圧作業の時間が長くなり、さらに外径φ２が１０ｍｍ以上になると、金属パイプ２２を収容する空間へ移動する後処理が困難（金属パイプ２２が太くなって曲げ難くいなど）となる結果となった。
【００５１】
よって、金属パイプ２２の外径φ２は１０ｍｍ以下、または真空層１５の外厚Ｄの２．５倍以下（φ２≦Ｄ×２．５：外厚Ｄが４ｍｍならば、外径φ２は１０ｍｍ）とするのが好ましい。また、金属パイプ２２を金属板１，２に溶接で接合する際に、真空層１５の内厚Ｃよりも金属パイプ２２が小さいと、金属パイプ２２の装着時に金属パイプ２２と金属板１，２とのギャップが大きくなって、溶接がしにくくなるので、金属パイプ２２の外径φ２は、真空層１５の内厚Ｃと同等かそれ以上の寸法（φ２≧Ｃ）とするのが好ましい。さらに、金属パイプ２２の内径φ３は、注入する圧縮空気の圧力や、減圧時の圧力などを考慮して、３ｍｍ以上のものを使用する。
【００５２】
金属板１，２の外周にある接合端部６は、前述の説明の通り、複合板９の拡張時に剥離や破壊が生じないように、２ｍｍの幅Ｗを有することが望ましいが、こうして最終的に得られた断熱板としての複合板９を、機器本体内に設けた被保温容器や被保冷容器などの周囲に、巻加工などで包囲させて使用する場合は、複合板９の両端の真空層１５を重ねて複合板９を巻装すると、この重なり部が厚くなって、機器本体への収納が困難になる問題があるが、金属板１，２の外周にある接合端部６の幅Ｗを積極的に広くし、この接合端部６を重ねて複合板９を筒状の状態で使用すれば、複合板９の重なり部の厚さを抑制でき、機器本体が大きくなる問題を防止できる。
【００５３】
図９は、複合板９を曲げ加工した後の状態を示すものである。複合板９は前述のように、使用箇所の形状に合わせて、例えば円筒若しくは角筒状に巻加工される。図９に示すものは、曲げ加工により４箇所の曲げ部３９ａ，３９ｂ，３９ｃ，３９ｄを四隅に形成し、その後、複合板９の両端に形成された接合端部６を重ね合わせて、リベット４０による固定を行なったものである。
【００５４】
また、ステップＳ５において真空層１５を内部に設けて、最終的な断熱材となる複合板９を加工した後、断熱材の外面となる金属板１，２の表面は、電解研磨やバフ研磨などで平滑面処理を施したり、または平滑面にした結果の光沢処理を施してもよい。このように、金属板１，２の表面の平滑性が向上することで、この金属板１，２の表面での電磁波（赤外線）の乱反射が抑制されると共に、電磁波の吸収面積が低減することで、熱エネルギーの反射性が高くなり、断熱性がより向上する。特に、金属板１，２としてアルミニウムを使用した場合は、元来アルミニウムがステンレスよりも熱エネルギーの反射効率が高い材質であることから、断熱性がより向上できることになる。
【００５５】
次に、上記説明で得られた複合板９の、各種機器への応用について説明する。図１０は、湯を沸かして保温する電気ポットや、炊飯を行いご飯を保温する炊飯器、またはご飯を保温するジャーなどの煮水装置の縦断面を表した模式図である。５１は煮水器の本体、５２は本体の上部開口部を覆う蓋体であり、これらの各部材の外郭は樹脂などで形成されている。本体５１の内部には、被加熱物を収容する容器５３が設けられている。この容器５３はステンレス製であって、内面にはフッ素樹脂の塗装が施されて塗装皮膜５４が形成されている。この塗装皮膜５４は容器５３の防腐食性を向上させるために形成されたものであり、フッ素樹脂以外の耐熱性の樹脂、例えば、シリコーン樹脂で塗装皮膜５４を形成してもよい。また、容器５３も、ステンレス製以外の金属製、例えば、アルミニウム製であってもよい。なお、蓋体５２の容器５３に対向している下面５２ａは、ステンレス製などの金属板で形成されている。また、容器５３は、側面部５３ａと底面部５３ｂが溶接部５３ｃで溶接接合されて容器状に形成されている。
【００５６】
容器５３の底面部５３ｂの下方には、加熱手段たる電熱ヒータ５５が設けられている。この電熱ヒータ５５は容器５３の底面を加熱するものである。なお、加熱手段を電熱ヒータ５５の代わりに電磁誘導用の加熱コイルで構成してもよい。加熱手段を加熱コイルで構成した場合、加熱コイルに対向して、容器５３の少なくとも一部を電磁誘導で発熱する磁性金属で構成する。こうすれば、加熱コイルに高周波電流を供給したときに、この加熱コイルからの交番磁界によって容器５３の磁性金属部が発熱し、容器５３を直接加熱することができる。
【００５７】
そして、容器５３の周囲には、前述のアルミニウム板から形成された複合板９が設けられている。容器５３の側面部５３ａには、複合板９ａが非接触に近接して設けられている。すなわち、複合板９ａと容器５３の側面部５３ａとの間には隙間５８が形成される。このように、複合板９ａを非接触に配置する理由は、アルミニウムは熱放射が少ない反面、熱伝導性が良いので、アルミニウム製の複合板９を被保温体である容器５３と接触状態に置くと、熱伝導で容器５３の熱が逃げやすくなり断熱性が低下するからである。また隙間５８の寸法は、静止空気層が形成される０．５〜９ｍｍとするのが好ましく、これよりも大きいと隙間９内で熱対流が生じ断熱性が低下する。
【００５８】
また、被保温体である容器５３がステンレスを母材とする場合、容器そのものはステンレスで熱放射が大きいものの、複合板９の外郭部材であるアルミニウム性の金属板１，２は熱反射性が良好なので、容器５３から放射される熱が、その外側にある複合板９で反射され、複合板９による真空断熱性を伴なって極めて効率のよい容器５３の断熱効果を得ることができる。また、ステンレス性の容器５３の内面にフッ素またはシリコーンの塗装皮膜５４を形成した場合には、塗布乾燥時に容器５３の外面にテンパ−カラーが発生し、これが熱放射を促進するが、上述のような複合板９の特性により、有効な断熱構造を得ることが可能になる。また、複合板９ａを非接触に配置することで、異なる金属（ステンレスとアルミニウム）間での電気腐蝕も防止できる。
【００５９】
その他、電熱ヒータ５５の外側たる下方には複合板９ｂが非接触に近接して設けられ、蓋体５２の下面５２ａの上方には複合板９ｃが非接触に近接して設けられている。すなわち、複合板９ｂと電熱ヒータ５５の下面との間に隙間５９が形成され、また、複合板９ｃと蓋体５２の下面５２ａとの間にも隙間６０が形成されている。
【００６０】
複合板９（９ａ，９ｂ，９ｃ）は、２枚のアルミニウム性の金属板１，２を接合して形成されたものであり、内部に真空層１５（１５ａ，１５ｂ，１５ｃ）を有している。このように、容器５３は四方の側面，底面，上面から複合板９に囲まれて覆われており、かつ、複合板９が容器５３と非接触状態に保たれることで、容器５３の熱が外部へ放散することが確実に防止されるようになっている。
【００６１】
なお、煮水装置が炊飯器のような容器５３を本体５１から着脱できる構造の場合、鍋である容器５３を収容する凹状の容器収容部を本体５１内に設け、この容器収容部の外周に複合板９を設置してもよい。また、容器５３の底部に加熱手段を備えるが、この加熱手段の外側下方に複合板９ｂを備える。他に加熱手段が容器５３や容器収容部の側面に配置される場合は、加熱手段の外側に複合板９ａを配置するのが好ましい。また、蓋体２の内部に加熱手段を配置してもよいが、この場合も、加熱手段の外側に真空断熱板６を配置するのが好ましい。いずれの場合も、複合板９と加熱手段との隙間を確保するために、点状や線状の接触はやむを得ないものの、極力非接触状態で複合板９を所望の位置に設けるのが好ましい。
【００６２】
さらに、加熱手段として前述の電磁誘導用の加熱コイルを用いた場合、加熱コイルの外側に複合板９ｂを配置すれば、複合板９ｂの材質が防磁効果を有するアルミニウムであることから、磁束の漏れを防止し、容器５３の加熱効率を向上させることができる。
【００６３】
別な例として、複合板９をオーブン付電子レンジの庫内の外面に備えれば、オーブン調理時に加熱効率が向上し、省エネルギーとすることができる。また、ホットプレートの下面に複合板９を備えれば、テーブル面の温度上昇を抑制できるためにホットプレートの面を従来よりも低く設定することができる。さらに、電磁誘導式コンロにおいて、加熱手段の下方に複合板９を備えれば、アルミニウムからなる金属板１，２の防磁効果によって、加熱効率の向上と共に床面への磁束の漏れを防止できる。こうして、各種の加熱および保温機器に対する断熱性の向上、断熱性および防磁性の向上、および省エネルギー性の改善などに寄与することができる。
【００６４】
図１１は、冷蔵庫への適用例を示したものである。同図において、６１は被保冷容器である庫内６２を形成する本体、６３は庫内６２の前面開口部を塞ぐ開閉自在な扉で、庫内６２の後方には、冷凍サイクルを構成する熱交換器６４および冷却手段６５が配置される。また６６は、庫内６２に設置された冷気放熱器で、ここから冷気が庫内６２に放散されるようになっている。そして、前述の複合板９は、庫内６２の天井面，底面および外面（後面および両側面）にそれぞれ設けられると共に、扉６３の内部にも設けられ、庫内６２のほぼ全周を取り囲んでいる。これらの断熱板９は、冷蔵庫外部から庫内６２への熱を遮断し、庫内６２の保冷性を良好に維持する。なお、冷蔵庫に限らず、ワインクーラーなど他の保冷機器にも同様に適用できる。
【００６５】
なお、冷蔵庫のような大型の機器に対しては、大きな複合板９が必要であるが、その場合は分割した複数の複合板９を組み込めばよい。また、乾燥炉やボイラーなどの断熱用として複合板９を用いる場合は、人間が接触する恐れのある高温部箇所に、断熱用遮蔽部材として複合板９を組み込めばよい。
【００６６】
図１２は、複合板９を加熱手段の反射板として利用した例を示している。同図において、７１は加熱手段としての電気ヒータ、７２はこの電気ヒータ７１により加熱される基台７３に載置された被加熱体で、電気ヒータ７１を挟んで被加熱体７２の反対側に反射板としての複合板９を配置する。この場合の複合板９の外郭部材（金属板１，２）は、熱反射性の良好なアルミニウムを選択する。電気ヒータ７１の輻射熱は、直接被加熱体７２に向かうと共に、複合板９により反射した輻射熱も被加熱体７２に向かう。そのため、被加熱体７２をより効率よく加熱することができる。加えて、電気ヒータ７１を配置していない複合板９の外側面の温度上昇は抑制され、例えば乾燥炉に応用した場合には、機器外郭の温度が低減できて安全性が向上すると共に、被加熱体７１への加熱効率も向上する。
【００６７】
以上のように、本実施例における断熱体の製造方法は、例えばアルミニウムを材料とする金属板１，２の表面に印刷を施し、この印刷面３を内面として複数の金属板１，２を重ね合わせ、圧延加工により金属板１，２間の非印刷面４，５を接合し、印刷面３に外気と連通する口部２１を設け、この口部２１より圧縮空気を挿入して金属板１，２間の印刷面３により膨張した密閉空間３１を形成し、その後口部２１より脱気して密閉空間３１を減圧した真空層１５として形成し、口部２１を例えば溶接などで閉塞している。
【００６８】
この場合、重ね合わせた複数の金属板１，２の被印刷面４，５を圧延加工により接合するので、接合の信頼性が高く、非印刷面４，５により形成される接合部（接合端部６と接合部７）における隙間もできにくい。また、真空層１５を形成する上での密閉空間３１の形成は、溶接ではなく圧延によるものなので、加工が容易で、密閉の信頼性も高く、長期にわたり真空層１５による断熱の効果を確保することができる。さらに、この真空層１５は、金属板１，２の表面に印刷面３を適宜パターンに施すことによって、自在な形状に形成できる。そのため、断熱体を使用する機器に応じて、四角や丸などの定形パターン以外の任意で且つ複雑な形状に形成できる。また、断熱体の内部にはシリカ粉末などの保持部材が存在しないため、断熱体の廃棄時に内部を分解・分別する必要がなく、金属板１，２を溶解すればリサイクルが容易である。
【００６９】
なお、金属板１，２の材料としてアルミニウムを選択すれば、ステンレスなどの重量の重い金属に比べて軽量化が図れ、大型の機器に容易に組み込むことができる。また、アルミニウムはステンレスよりも外面からの熱放射が少ないので、断熱性をより高めることができる。
【００７０】
さらに、ステンレス製の容器や鍋の周囲に包囲して断熱体を使用する場合は、こうした容器や鍋の内面塗装などで、その外面にテンパーカラーが発生しても、断熱体が熱を逃がさないようにするので、断熱性に悪影響を与えないようにすることができる。
【００７１】
また、このような製造方法においては、アルミニウム，ステンレス，チタンまたはその合金のいずれかから金属板１，２の材料を選択すると共に、圧延加工による接合部７を複数形成するのが好ましい。
【００７２】
こうすると、断熱体を使用する機器毎に、要求される断熱性能や断熱体の設置環境が異なるので、こうした断熱性能や設置環境に適した金属板１，２の材料を、アルミニウム，ステンレス，チタンまたはその合金などから任意に選択することができる。例えば、高温多湿環境の場合には耐食性に優れたステンレスを選択し、軽量性が必要な場合にはチタンを選択する。また、被保温容器に接触させて使用せざるを得ない場合には、被保温容器と同じ材料のものを選択して電蝕を防止する。さらに、ステンレスはアルミニウムよりも熱伝導性が低いので、断熱体に熱伝導がある場合には、低熱伝導性のステンレスを選択する。また、断熱体を機器の外郭部材と兼用して使用する際も、強度や硬さが必要とされる場合は、ステンレスを選択する。さらに、金属アレルギーを防止するにはチタンを選択すればよい。
【００７３】
また、圧延加工による接合部８が複数形成されていれば、接合部７の金属板１，２間の梁強度によって、脱気減圧時に膨張させた金属板１，２の非接合部８における変形を抑制することができる。そのため、真空層１５の加工時に、一旦拡張させて形成した密閉空間３１の容積を減少させてしまい、断熱性能を低下させる不具合を一掃できる。また、こうした変形を防止するのにわざわざ金属板１，２を厚くすることもなく、断熱体全体の重量は増加しない。
【００７４】
特に、比較的強度が弱いとされるアルミニウムを金属板１，２の材料として選定した場合でも、金属板の変形を抑止して真空層１５の形成が可能であり、軽量で且つ断熱性に優れた真空の断熱体が形成可能になる。
【００７５】
また、このような製造方法においては、圧延加工による接合部７を複数形成し、各接合部７間の距離を圧延加工後における金属板１，２の材料厚さＴ‘の５０倍以内とし、各接合部７の面積Ｓを５ｍｍ２以上とすると共に、各接合部１，２の外周を例えば角Ｒ部３６のような曲線状に形成するのが好ましい。
【００７６】
このように、事前の実験結果に基づき、複数の接合部７間の距離を最適な５０倍以内に選定しておけば、種々の形状の断熱体を新規設計する際にも、再度の検討をわざわざ行なうことなく、脱気減圧時に膨張させた金属板１，２の変形を防止できる。これにより、断熱体の内部にシリカ粉末などの別の保持部材を介在させることなく、望ましい断熱性能を有する真空層１５を形成した軽量の断熱体を製造できる。
【００７７】
一方、真空層１５の断熱層を効率よく利用するには、金属板１，２間での熱伝導を極力少なくすることが必要で、そのためには接合部７の面積Ｓを小さくするのが好ましいが、逆にこの面積Ｓが少なすぎて、圧縮空気３１の挿入時に接合部７の剥離に伴なう金属板１，２の破壊が生じると、真空層１５そのものが形成できなくなる致命的問題を生じる。そこで、このような相反する問題を実験で実証した結果に基づき、各接合部７の面積Ｓを５ｍｍ２以上とし、且つ各接合部７の外周を曲線状に形成すれば、圧縮空気３１の注入時に接合部７が剥離したり、金属板１，２が破壊する不具合を確実に防止できる。
【００７８】
また、このような製造方法においては、複数の金属板１，２の外周に圧延加工による接合端部６を２ｍｍ以上の幅Ｗで形成し、この接合端部６どうしを重ね合わせて断熱体を筒状に形成するのが好ましい。
【００７９】
真空層１５の断熱層を効率よく利用するには、金属板１，２間での熱伝導を極力少なくすることが必要で、そのためには接合端部６の面積を小さくするのが好ましいが、逆にこの面積が少なすぎて、圧縮空気３１の挿入時に接合端部６の剥離に伴なう金属板１，２の破壊が生じると、真空層１５そのものが形成できなくなる致命的問題を生じる。そこで、このような相反する問題を実験で実証した結果に基づき、圧延加工により複数の金属板１，２間の外周に形成される接合端部７を２ｍｍ以上の幅Ｗとすることにより、圧縮空気３１の注入時に接合端部６が剥離したり、金属板１，２が破壊する不具合を確実に防止できる。
【００８０】
また、例えば電気ポットなどの機器の容器外側へ断熱体である完成した複合板９を巻加工して装着する場合は、真空層１５どうしや、真空層１５と接合端部６とを重ねて複合板９の端部を処理すると、真空層１５がある分だけ重なり部の厚さが厚くなり、複合板９を収容する機器本体が大きくなる問題があるが、接合端部６どうしを重ねて複合板９を巻加工すれば、必要以上に複合板９が厚くならず、機器本体を必要以上に大きくしなくて済む。また、重なり部に真空層１５が存在しないので、この重なり部をリベットなどの止着具で固定し、筒状の複合板９を予め形成すれば、容器などへの装着性を改善できる。
【００８１】
また、このような製造方法においては、口部２１を閉塞した後、金属板１，２の外面を平滑面または光沢面仕上げする後処理工程を追加して行うのが好ましい。
【００８２】
この場合、金属板１，２の外面を平滑面または光沢面仕上げすることで、電磁波（赤外線）の反射性が向上するため、保温容器などからの熱放射を反射して、複合板９の熱吸収を抑制し、複合板９の断熱効果をより高めることができる。また、外観に複合板９が露出する場合にも外観性が向上する。
【００８３】
また、本実施例における製造方法は、金属板１，２の表面に印刷を施し、この印刷面３を内面として前記複数の金属板１，２を重ね合わせ、圧延加工により金属板１，２間の非印刷面を接合し、印刷面３に外気と連通する口部２１を設け、この口部２１に金属板３と同材料の筒体としての金属パイプ２２を接合し、この金属パイプ２２より圧縮空気を挿入して金属板１，２間の印刷面３により膨張した密閉空間３１を形成し、その後金属パイプ２２より脱気して密閉空間３１を減圧した真空層１５として形成し、金属パイプ２２を閉塞すると共に、金属パイプ２２は真空層１５の内厚Ｃ以上で、１０ｍｍ以下または真空層１５の外厚Ｄの２．５倍以下の外径φ２を有している。
【００８４】
さらに、口部２１に金属板１，２と同材料の金属パイプ２２を溶接などで接合し、この筒体より圧縮空気を挿入して、印刷面に対応して非接合部８となる箇所で、膨張した密閉空間３１を形成し、その後金属パイプ２２より空気を抜いて密閉空間内を減圧して真空層１５を形成した後、金属パイプ２２を溶接などで閉塞することで、所望の複合板９を得ることができる。そのため、共通する金属パイプ２２により金属板１，２間の内部拡張と密閉空間３１の減圧を兼用することができ、合理的で加工性を向上できる。
【００８５】
また、金属パイプ２２の外径を１０ｍｍ以下または真空層１５の外厚の２．５倍以下とすることで、圧縮空気３１の注入や、金属板１，２間の脱気減圧に支障がなくなると共に、金属パイプ２２の開口面積を極力小さくすることで、金属パイプ２２の端部開口部における溶接密閉加工が容易になる。さらに、機器の内部に複合板９を収容したときにも、この金属パイプ２２の収容空間が極力少なくなって、機器の大型化を防ぎ、また金属パイプ２２の収容空間に金属パイプ２２を位置させるための曲げ加工や潰し加工なども支障なく行える。
【００８６】
さらに、金属パイプ２２の外径を真空層１５の内厚以上とすることにより、圧縮空気の注入や、金属板１，２間の脱気減圧作業を円滑に行えると共に、金属パイプ２２を金属板１，２に挿入する際に金属板１，２とのギャップが生じにくく、金属パイプ２２を同じ材料からなる金属板１，２に溶接などで簡単に接合できる。
【００８７】
また、本実施例における断熱体は、材厚Ｔが１．２〜２．８ｍｍで純度９９％以上の純アルミニウムからなる金属板１，２の表面に印刷を施し、この印刷面３を内面として複数の金属板１，２を重ね合わせ、各接合部７の面積Ｓが約１２ｍｍ２で、接合部７間の距離Ｌが１５ｍｍ以内となり、且つ金属板１，２が１／４の材厚になるように約４倍に圧延加工して、金属板１，２間の非印刷面５を接合し、印刷面３に外気と連通する口部２１を設け、この口部２１より６０〜１２０Ｐａの圧縮空気を挿入して、金属板１，２を含めた材厚Ｄが約４ｍｍとなるように、金属板１，２間の印刷面３により膨張した約３ｍｍの厚さを有する密閉空間３１を形成し、その後口部２１より脱気して密閉空間３１を減圧した約１３３Ｐａの内部真空度を有する真空層１５として形成し、口部２１を閉塞して製造される。
【００８８】
この場合、重ね合わせた複数の金属板１，２の被印刷面４，５を圧延加工により接合するので、接合の信頼性が高く、非印刷面４，５により形成される接合部（接合端部６と接合部７）における隙間もできにくい。また、真空層１５を形成する上での密閉空間３１の形成は、溶接ではなく圧延によるものなので、加工が容易で、密閉の信頼性も高く、長期にわたり真空層１５による断熱の効果を確保することができる。さらに、この真空層１５は、金属板１，２の表面に印刷面３を適宜パターンに施すことによって、自在な形状に形成できる。そのため、断熱体を使用する機器に応じて、四角や丸などの定形パターン以外の任意で且つ複雑な形状に形成できる。また、断熱体の内部にはシリカ粉末などの保持部材が存在しないため、断熱体の廃棄時に内部を分解・分別する必要がなく、金属板１，２を溶解すればリサイクルが容易である。
【００８９】
また、金属板１，２として材厚Ｔが１．２〜２．８ｍｍの純アルミニウムを選択し、各接合部６の面積Ｓが約１２ｍｍ２で、接合部６間の距離Ｌを１５ｍｍ以内とし、金属板１，２を約４倍に圧延加工し、口部２１より６０〜１２０Ｐａの圧縮空気を挿入し、金属板１，２を含めた材厚Ｄが約４ｍｍとなるように、約３ｍｍの厚さを有する密閉空間３１を形成すれば、金属板１，２の内部を拡張する際に、母材である金属板１，２の破壊を防止できると共に、真空層１５となる密閉空間３１を確実に形成できる。
【００９０】
さらに、アルミニウムからなる金属板１，２の場合、１９９．５Ｐａ以下、好ましくは約１３３Ｐａ以下の内部真空度を有する真空層を形成すれば、真空層１５としての断熱性を確保できる。逆に、真空度が高くなると、減圧時に密閉空間３１を形成した箇所で金属板１，２の変形が起きやすくなるが、１３．３Ｐａ以上の真空度があれば、こうした変形を防止でき、所定の真空容積を有し、しかも断熱性に優れた軽量の複合板９を製造することができる。
【００９１】
なお本発明は上記実施例に限定されるものではなく、本発明の要旨の範囲内で適宜変更が可能である。
【００９２】
【発明の効果】
本発明の請求項１における断熱体の製造方法によれば、真空層を自在な形状で簡単に加工して得ることができ、断熱性やリサイクル性にも優れた断熱体を得ることができる。
【００９３】
本発明の請求項２における断熱体の製造方法によれば、断熱性能や設置環境に適した金属体の材料を任意に選択することができる。また、金属体を厚くすることなく、真空層の加工時において断熱性能を低下させる不具合を一掃できる。
【００９４】
本発明の請求項３における断熱体の製造方法によれば、望ましい断熱性能を有する真空層を形成した軽量の断熱体を製造できる。また、空気の注入時に接合部が剥離したり、金属体が破壊する不具合を確実に防止できる。
【００９５】
本発明の請求項４における断熱体の製造方法によれば、断熱体を巻加工したときに、必要以上に断熱体が厚くならず、また容器などへの装着性を改善できる。
【００９６】
本発明の請求項５における断熱体の製造方法によれば、断熱体の断熱効果をより高めることができると共に、断熱体が外部に露出する場合に外観性を向上できる。
【００９７】
本発明の請求項６における断熱体の製造方法によれば、真空層を自在な形状で簡単に加工して得ることができ、断熱性やリサイクル性にも優れた断熱体を得ることができる。また、共通する筒体により金属体間の内部拡張と空間の減圧を兼用することができ、合理的で加工性を向上できる。さらに、金属体間の脱気減圧，端部開口部における溶接密閉加工，および筒体の曲げ加工や潰し加工なども支障なく行なうことができる。
【００９８】
本発明の請求項７における断熱体の製造方法によれば、真空層を自在な形状で簡単に加工して得ることができ、断熱性やリサイクル性にも優れた断熱体を得ることができる。また、金属体の内部を拡張する際に、母材である金属体の破壊を防止できると共に、真空層となる空間を確実に形成でき、さらに真空層としての断熱性も確保できる。
【図面の簡単な説明】
【図１】本発明の好ましい実施例における断熱体の製造方法の各工程を示すフローチャートである。
【図２】同上、圧延加工前の金属板へシルク印刷を施した状態の平面図である。
【図３】同上、圧延加工前の２枚の金属板を重ね合わせた状態の正面図である。
【図４】同上、圧延加工後に得られた複合板の断面図である。
【図５】同上、圧延加工後の外形抜きを行なった後の複合板の平面図である。
【図６】同上、通気口より圧縮空気を注入した後の断面図である。
【図７】同上、真空層形成工程の終了直後における複合板の断面図である。
【図８】同上、図５における要部の拡大図である。
【図９】同上、曲げ加工後における複合板の断面図および側面図である。
【図１０】同上、複合板を組み込んだ煮水器の縦断面の模式図である。
【図１１】同上、複合板を組み込んだ冷蔵庫の縦断面の模式図である。
【図１２】同上、複合板を電気ヒータの反射板として適用した側面図である。
【符号の説明】
１，２ 金属板（金属体）
４，５ 非印刷面（非印刷部）
６ 接合端部（端部）
７ 接合部
１５ 真空層
２１ 口部
２２ 金属パイプ（筒体）
３１ 密閉空間（空間）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a heat insulator provided in various devices having a heat retaining function and a cold retaining function.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in home electric appliances such as electric pots, rice cookers, and heat retaining jars having a heat retaining function, energy saving by improving heat insulation has been an important issue. Further, in cold storage devices such as refrigerators and wine coolers, it is necessary to improve cold storage for energy saving. Also, for the purpose of lowering the outer surface temperature for safety, not for energy saving, improvement of heat insulation is also an important factor in equipment such as a drying oven, a boiler, and an electric heater. It is known that vacuum heat insulation is one of effective means for such technical problems of energy saving and heat insulation improvement.
[0003]
There are various means for forming a vacuum layer, but in a reduced-pressure vacuum environment, the ends between a plurality of metal plates are hermetically bonded to create a vacuum, or a suction hole serving as a mouth is provided between the plurality of metal plates. It is common to deaerate from a suction hole with a vacuum pump or the like. At present, the following two methods are employed in electric pots and the like.
[0004]
The first method is to use a vacuum vessel made of stainless steel for a vessel requiring heat insulation, which is known as a metal double-walled vessel in Patent Document 1 and the like. In this case, at the time of manufacturing, a double container in which the stainless steel outer container is faced to the outside of the stainless steel inner container while forming a predetermined gap, and the ends of the inner container and the outer container are welded all around. At the same time, the internal space is evacuated to a vacuum.
[0005]
The second method is a heat insulator using silica powder disclosed in Patent Document 2, for example. Specifically, a case is formed by putting low thermal conductivity silica powder or the like inside a bag such as a non-woven fabric, and then putting the bag into a metal sheet bag such as an aluminum foil, and forming the housing in a decompression chamber. The end is sealed and a vacuum is formed between the silica powders inside.
[0006]
[Patent Document 1]
JP-A-7-223089
[Patent Document 2]
JP-A-62-13979
[0007]
[Problems to be solved by the invention]
In the first method, in order to maintain the strength as a vacuum container, a stainless steel material having a material thickness (material thickness) of 0.5 to 2.0 mm or more has to be used. Therefore, the weight of the whole container as a heat insulator is heavy. In addition, the entire inner periphery of the inner container and the outer container must be welded, so that the number of processing steps is increased and a welding operation is involved. In addition, since stainless steel with good corrosion resistance is used for the inner container, the outer container must also be made of stainless steel to ensure weldability. Heat is dissipated from the container, which is a factor in lowering the heat insulating property.
[0008]
In addition, when the interior of the inner container is coated with a fluorine paint or the like, the vacuum container is exposed to a high temperature when the coating is dried, and a temper color (a stainless steel oxide film) is generated on the outer container, and the heat radiation is further increased. In addition, since it is made of stainless steel and its entire peripheral end is welded, it is difficult to manufacture a large-sized one in terms of weight and cost. For this reason, the present invention is limited to the implementation of a small product as a heat insulating material, and cannot be practically applied to a larger product such as a refrigerator or a drying oven.
[0009]
On the other hand, in the second method, a lighter sheet-like heat insulator can be obtained as compared with the first method, but on the other hand, silica powder or the like is filled inside to maintain a vacuum housing. There is a problem that heat insulation deteriorates heat insulation. Also, when the heat insulator is bent, the aluminum foil on the outer surface of the heat insulator is easily damaged, and the sealing formed in the aluminum foil cannot be welded because the aluminum foil itself is thin and cannot be welded. And the like, resulting in poor sealing reliability. For this reason, there is a disadvantage that it is difficult to maintain the internal vacuum due to the leak from the damaged portion or the sealing portion.
[0010]
In addition, since a metal sheet bag made of aluminum foil or the like has the final outer shape of the heat insulator, it is difficult to freely change the shape of the vacuum layer and the heat insulator other than the rectangular shape. Furthermore, when sealing with a heat seal, the inner material is different from the outer material, and there is a difference in the coefficient of thermal expansion of each material. A gap is easily formed due to the difference between the inside and outside of the portion and the thermal expansion, and as a result, the above-described leakage property is easily reduced. Moreover, the silica powder as the housing holding member needs to be separated from the metal when the heat insulator is discarded, and is inferior in recyclability.
[0011]
The present invention is intended to solve the above-described problems, and provides a method for manufacturing a heat insulator that can be obtained by easily processing a vacuum layer in an arbitrary shape and that has excellent heat insulating properties and recyclability. The primary purpose is to provide.
[0012]
A second object of the present invention is to provide a method for manufacturing a heat insulator that can be easily incorporated into a lightweight and large-sized device.
[0013]
[Means for Solving the Problems]
In the method for manufacturing a heat insulator according to the first aspect of the present invention, the vacuum layer can be formed in a desired shape by appropriately printing the metal body with a printed portion. Therefore, it can be formed into an arbitrary and complicated shape other than a fixed pattern such as a square or a circle, depending on the device using the heat insulator. Further, since there is no holding member such as silica powder inside the heat insulator, there is no need to disassemble and separate the inside of the heat insulator at the time of disposal, and if the metal body is dissolved, recycling is easy.
[0014]
In the method for manufacturing a heat insulator according to claim 2 of the present invention, the required heat insulation performance and the installation environment of the heat insulator are different for each device using the heat insulator. The material can be arbitrarily selected from aluminum, stainless steel, titanium or an alloy thereof. For example, in a high-temperature and high-humidity environment, stainless steel excellent in corrosion resistance is selected, and when lightness is required, titanium is selected. If it is necessary to use the heat-insulated container in contact with the heat-insulated container, the same material as the heat-insulated container is selected to prevent electrolytic corrosion. Further, since stainless steel has lower thermal conductivity than aluminum, if the heat insulator has thermal conductivity, stainless steel having low thermal conductivity is selected. Also, when the heat insulator is used also as an outer member of the equipment, if strength and hardness are required, stainless steel is selected. Further, titanium can be selected to prevent metal allergy.
[0015]
Further, if a plurality of joints are formed, the deformation of the non-joined portions of the metal body expanded at the time of degassing and decompression can be suppressed by the beam strength between the metal bodies between the joints. Therefore, at the time of processing the vacuum layer, it is possible to eliminate the problem that the volume of the space once expanded and formed is reduced and the heat insulation performance is reduced. Further, the metal body is not thickened to prevent such deformation, and the weight of the entire heat insulator does not increase.
[0016]
In the method for manufacturing a heat insulator according to claim 3 of the present invention, if the distance between the joints is selected within an optimal predetermined multiple based on the experimental results, the heat insulator of various shapes can be newly designed. In addition, it is possible to prevent the deformation of the expanded metal body at the time of degassing and depressurizing without reexamination. This makes it possible to manufacture a light-weight heat insulator having a vacuum layer having desirable heat-insulating performance without interposing another holding member such as silica powder inside the heat insulator.
[0017]
On the other hand, in order to use the heat insulating layer of the vacuum layer efficiently, it is necessary to minimize the heat conduction between the metal bodies. To this end, it is preferable to reduce the area of the joint, but on the contrary, Is too small, and the metal body is destroyed due to peeling of the joint when air is inserted, causing a fatal problem that the vacuum layer itself cannot be formed. Therefore, based on the experimental results, the area of each joint is set to about 5 mm. 2 If the joint is formed in a curved shape as described above, it is possible to reliably prevent the joint from peeling off or the metal body from being broken when air is injected.
[0018]
In the method of manufacturing a heat insulator according to claim 4 of the present invention, when the heat insulator is wound around the outside of a container of an apparatus such as an electric kettle, for example, the vacuum layers are overlapped with each other, or the vacuum layer and the end are overlapped. When the end of the heat insulating part is treated, the thickness of the overlapping part becomes thicker by the amount of the vacuum layer, and there is a problem that the equipment body that houses the heat insulator becomes large. By performing the winding process, the heat insulator does not become unnecessarily thick, and the device body does not need to be made unnecessarily large. In addition, since there is no vacuum layer in the contact portion, if the contact portion is fixed with a fastener such as a rivet and a tubular heat insulator is formed in advance, the mountability to a container or the like can be improved.
[0019]
In the method for manufacturing a heat insulator according to the fifth aspect of the present invention, since the reflectivity of electromagnetic waves (infrared rays) is improved by finishing the metal body with a smooth or glossy finish, heat radiation from a heat insulation container or the like is reflected, and the heat insulation is performed. Heat absorption of the body can be suppressed, and the heat insulating effect of the heat insulating body can be further enhanced. In addition, the appearance is improved even when the heat insulator is exposed to the outside.
[0020]
In the method for manufacturing a heat insulator according to the sixth aspect of the present invention, the vacuum layer can be formed in any shape by appropriately printing the metal body with a printed portion. Therefore, it can be formed into an arbitrary and complicated shape other than a fixed pattern such as a square or a circle, depending on the device using the heat insulator. Further, since there is no holding member such as silica powder inside the heat insulator, there is no need to disassemble and separate the inside of the heat insulator at the time of disposal, and if the metal body is dissolved, recycling is easy.
[0021]
Furthermore, a cylinder of the same material as the metal plate is joined to the mouth by welding, etc., and compressed air is inserted from this cylinder to expand the sealed space at the non-joined portion corresponding to the printing surface. After forming, a vacuum layer is formed by evacuating air from the cylinder and depressurizing the enclosed space, and then closing the cylinder by welding or the like, a desired heat insulator can be obtained. For this reason, the internal expansion between the metal plates and the decompression of the closed space can be shared by the common cylindrical body, and the rational and workability can be improved.
[0022]
In addition, by setting the diameter of the cylindrical body to a predetermined value or less or a predetermined multiple of the outer thickness of the vacuum layer or less, the injection of compressed air and the deaeration between metal bodies are not hindered, and the opening area of the cylindrical body is reduced. By making it as small as possible, welding sealing at the end opening is facilitated. Furthermore, even when a heat insulator is housed inside the equipment, the housing space for this cylinder is reduced as much as possible, preventing the equipment from becoming large, and bending to position the cylinder in the housing space for the cylinder. And crushing can be performed without any trouble.
[0023]
Furthermore, by making the diameter of the cylinder equal to or larger than the inner thickness of the vacuum layer, the injection of compressed air and the deaeration and decompression work between the metal plates can be performed smoothly, and the metal body is inserted when the cylinder is inserted into the metal body. A gap is hardly generated between the cylindrical body and the metal body, and the cylindrical body can be easily joined to the metal body by welding or the like.
[0024]
In the method for manufacturing a heat insulator according to claim 7 of the present invention, the vacuum layer can be formed into a free shape by appropriately printing the printed surface on the surface of the metal body. Therefore, it can be formed into an arbitrary and complicated shape other than a fixed pattern such as a square or a circle, depending on the device using the heat insulator. Further, since there is no holding member such as silica powder inside the heat insulator, there is no need to disassemble and separate the inside of the heat insulator at the time of disposal, and if the metal body is dissolved, recycling is easy.
[0025]
Also, the area of the joint is about 12 mm 2 Then, if the gap between the joints is within a predetermined value, the metal plate is processed to a predetermined thickness, gas is inserted from the mouth, and if a space is formed so that the material thickness including the metal body becomes a predetermined value, metal When the inside of the body is expanded, it is possible to prevent the metal body, which is the base material, from being broken, and to reliably form a space serving as a vacuum layer.
[0026]
Furthermore, by forming a vacuum layer having a predetermined degree of vacuum, it is possible to secure heat insulation as a vacuum layer, prevent deformation of a metal body, have a predetermined vacuum volume, and have a light weight excellent in heat insulation. Insulation can be manufactured.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the method for manufacturing a heat insulator according to the present invention will be described with reference to the accompanying drawings. 1 to 12 show an embodiment of the present invention, and the following description will be made in accordance with the flowchart of FIG. 1 showing the procedure of a method of manufacturing a heat insulator.
[0028]
In FIG. 2 showing a state before rolling, reference numeral 1 denotes a metal plate serving as an outer member of a heat insulator, which is formed mainly of aluminum, stainless steel, titanium, or an alloy of these metals. Separately from this metal plate 1, a metal plate 2 having the same main material and material thickness and serving as an outer member of the heat insulator is prepared (see FIG. 3). That is, here, at the time of manufacturing the heat insulator, at least two or more metal plates 1 and 2 are provided in advance. In the following description, an example in which an aluminum plate is used as the metal plates 1 and 2 that are metal bodies will be described. However, the metal plates 1 and 2 are formed of the same material other than aluminum or different materials. The optimum material may be appropriately selected according to the purpose of use.
[0029]
As a manufacturing process of the heat insulator, first, as shown in FIG. 1, a printing process (step S1) for forming a desired vacuum layer pattern described later is performed. That is, a heat-resistant paint such as carbon, silica, alumina, titania, silicone, or fluorine is coated on one surface of a metal plate 1 made of an aluminum plate having a material thickness of about 2 to 6 mm in a predetermined shape, for example, by silk printing. This is the step of printing. As a result, a printing surface 3 which is a continuous printing portion of an arbitrary pattern is formed on one surface of the metal plate 1. Since the portion where this printing is performed finally corresponds to the vacuum layer 15 (see FIG. 7), the printing surface 3 is pattern-printed in a shape for forming the vacuum layer 15. Therefore, printing is not performed on the periphery of the metal plate 1, and the non-printing surface 4, which will be a joint end later, is formed there. In addition to the joining end portion 4, a non-printing surface 5 which is a non-printing portion surrounded by the printing surface 3 and which has not been subjected to printing is intentionally formed as a joining portion.
[0030]
In the printing process of step S1, the paint used for printing is obtained by mixing fine powder of, for example, carbon, silica, silicone, alumina, or the like with a solvent. As shown in (1), only the inorganic fine powder remains as the printing surface 3 in a predetermined pattern. At this time, if the printing surface 3 is formed by silk screen printing or the like, the finally obtained vacuum layer 15 can be freely shaped by arbitrarily changing the printing pattern. In addition, the material of the paint is not limited to the above-mentioned material, and it is essential that the material has heat resistance.
[0031]
In the next step S2, a step of rolling the plurality of metal plates 1 and 2 in contact with each other, that is, for example, is performed. In this rolling step, as shown in FIG. 3, the pair of metal plates 1 and 2 are overlapped so as to sandwich the printing surface 3 therebetween. FIG. 3 shows a state before rolling in which two metal plates 1 and 2 are superimposed, and reference symbol t denotes a material thickness of the entire metal plates 1 and 2. Then, while heating the two superposed metal plates 1 and 2, the metal plates 1 and 2 are pressure-rolled between rollers (not shown) to reduce the material thickness t ′ of the entire metal plates 1 and 2 to 1 /. Reduce the thickness to about 4. FIG. 4 shows a state after rolling, and the material thickness t ′ of the entire metal plates 1 and 2 at this time is １, that is, １ ／ t before rolling. In this embodiment, as described above, the thickness T (see FIG. 2) of each of the metal plates 1 and 2 before rolling is 2 to 6 mm, and the total thickness t is 4 to 12 mm. The total thickness t ′ of the metal plates 1 and 2 as the composite material is about １ ／ t = 1 to 3 mm, and the thickness T ′ of the individual metal plates 1 and 2 is ＴT = 0.5 to 1. 5 mm (see FIG. 5).
[0032]
By this pressure rolling, the two metal plates 1 and 2 are strongly bonded to each other by the intermolecular attractive force of the same material on the non-printing surfaces 4 and 5. And the printing surface 3 are different materials, so that they are not joined. That is, after the pressure rolling, the non-printing surfaces 4 and 5 where the metal plates 1 and 2 are in direct contact with each other form the bonding end 6 and the bonding portion 7 which are ends, whereas the metal plate 2 and the A non-joined portion 8 is formed by the printing surface 3 that comes into contact with the sheet, and a composite plate 9 as a composite partially joined by the joined end portion 6 and the joined portion 7 is obtained.
[0033]
The printing surface 3 is formed in a continuous pattern, but an extension 10 having a width and a length of about 3 to 30 mm is formed at a part of an end of the metal plate 1. The extension 10 forms an opening 21 used to insert or deaerate air, that is, compressed air. After the rolling process in step S2, the periphery of the composite plate 9 is cut in accordance with the outer shape of the final product, and a part of the printing surface 3 is exposed at the end of the composite plate 9 during the cutting. Is also good. FIG. 2 shows a cut portion C having an outer shape (a punched outer shape after rolling) of the product. In this embodiment, the extension 10 is formed so as to protrude so that the tip of the extension 10 is exposed after the cutting of the composite board 9. However, the extension 10 is not formed, and a part of the printing surface 3 is cut at the time of cutting. May be exposed at the end of the composite plate 9. FIG. 5 shows a state in which the composite plate 9 is cut into a desired shape after the two metal plates 1 and 2 are roll-joined. The corners of the composite plate 9 after the cut are square. Rather, the curved (R) shape is preferable because it is easy to handle.
[0034]
The next step S3 is a vent forming process for forming a desired vent 11, which utilizes the extension 10 to be the date joint 8. First, the end of the composite plate 9 located at the extension 10 is expanded using a jig (not shown), and the expanded mouth 21 (see FIG. 7) is made of the same material as the metal plates 1 and 2. For example, after inserting a metal pipe 22 made of aluminum, the base end of the metal pipe 22 is joined to the composite plate 9 by welding, and a vent 21 is formed by the mouth 21 and the metal pipe 22. After the joining, as shown in FIG. 7, a welded portion 24 is provided on the inner surface of the mouth portion 21 and the circumferential surface on the base end side of the metal pipe 22. The method of closing the ventilation port 23 is not limited to welding, but if welding is used, a gap is less likely to be formed as compared with a conventional heat seal, and sealing reliability is high.
[0035]
The next step S4 is a step of injecting compressed air into the composite plate 9. This is a step of injecting compressed air into the non-joined portion 8 in the composite plate 9 obtained by the printing surface 3 at a pressure of at least 5 Pa or more and 150 Pa or less, preferably 60 to 120 Pa from the vent 23. FIG. 6 shows a state immediately after the compressed air is injected from the port 23. At the time of injecting compressed air, pressing dies 26 and 27 are respectively provided on the upper surface (one side surface) and the lower surface (other side surface) of the composite plate 9 to restrict the composite plate 9 from expanding more than necessary. The gap d between the upper holding die 26 and the lower holding die 27 is preferably about 2 to 6 mm. In this way, when the compressed air is injected into the non-joining portion 8 in the composite plate 9, the pressure of the air pushes the aluminum metal plates 1 and 2 outward to expand. When the composite plate 9 expands to some extent, the outer surfaces of the metal plates 1 and 2 come into contact with the pressing dies 26 and 27 to restrict the swelling, so that the composite plate 9 has a predetermined thickness and serves as an air space inside the composite plate 9. Is formed.
[0036]
The welding of the metal pipe 22 in step S3 may be performed after expanding the metal plates 1 and 2 with compressed air. In this case, the end of the composite plate 9 located at the extension 10 is partially expanded with a jig, and compressed air is directly injected from the expanded opening 21.
[0037]
In the step S4, if the pressure of the compressed air to be injected is small, the inside of the composite plate 9 does not expand sufficiently, and if the pressure of the compressed air is too high, the joint 7 including the joint end 6 is not expanded. It is necessary to select the pressure in consideration of the material and the material thickness of the metal plates 1 and 2 because there is a possibility that the metal plates 1 and 2 may be peeled off or the metal plates 1 and 2 as the base material may be broken. Incidentally, when an aluminum plate having a purity of 99% or more such as A1050 series or A1100 series and having a thickness T before rolling of about 2 mm (preferably 1.2 to 2.8 mm) is used as a base material, When a four-fold rolling is performed in the rolling step of S2, the thickness of the base material alone becomes 0.5 mm (0.3 to 0.7 mm in a preferable range). In the compressed air injection step of step S4, the total material thickness D is set to 4 mm (in a preferable range, 2 to 6 mm), and the thickness C of the closed space 31 and thus the final vacuum layer 15 is set to about 3 mm. In the expanded experiment, if the injection pressure of the compressed air is less than 10 Pa, the inside of the composite plate 9 does not expand sufficiently, and if the pressure becomes 130 Pa or more, the joint end 6 and the joint 7 are peeled off. The metal plates 1 and 2 that are the base materials There was found. If the pressure is 50 Pa or less, it takes a little longer to extend to every corner of the non-joined portion 8, and the workability is deteriorated. Therefore, it is preferable that the injection pressure of the compressed air be in the range of 60 to 120 Pa so that the workability does not deteriorate and the inside of the composite plate 9 can be properly expanded.
[0038]
However, even if the injection pressure of the compressed air is in an appropriate range, if the area of the bonding end portion 6 or the bonding portion 7 in the rolling process is small, the bonding strength is weakened. There is a risk that the bonding end portions 6 and the bonding portion 7 may peel off, or the metal plates 1 and 2 as the base material may be broken. Therefore, as described above, an aluminum plate having a purity of 99% or more, such as A1050 series or A1100 series, and having a thickness T before rolling of about 2 mm is used as a base material, and the base material alone has a material thickness T ′ of 0%. In the sample product which was rolled four times in the rolling step so as to have a diameter of 0.5 mm, the diameter φ of the substantially circular joint 7 was 2 mm (the area S was about 3 mm). 2 ), The above-mentioned peeling or destruction occurs, and the diameter φ = 2.5 mm (the area S = about 4.9 mm). 2 In the case of ()), although it is slightly peeled, there is no destruction, and it can be used somehow, and the diameter φ = 3 mm (the area S = about 7 mm) 2 In the case of (2), the result was obtained that there was no problem without peeling or destruction. Therefore, the area S of the joint 7 is 5 mm 2 , Preferably 7mm 2 By doing so, it is possible to reliably prevent the joint 7 from peeling off when the compressed air is injected or the metal plates 1 and 2 from being broken.
[0039]
Furthermore, in order to secure a vacuum layer 15 as wide as possible in consideration of heat insulation, the joint end 6 formed on the outer periphery of the composite plate 9 is desired to be as narrow as possible. In consideration of reliably preventing peeling from the metal plate 6 and destruction of the metal plates 1 and 2, it is preferable to secure at least the width W of the joint end 6 at least 2 mm over the entire periphery of the composite plate 9.
[0040]
In connection with this, in the pattern shape of each joint 7, if there is a sharp corner on the outer periphery, pressure is concentrated on the corner of the joint 7 when the compressed air is injected, and the joint 7 is peeled off. There is a concern that the metal plates 1 and 2 may be broken. Therefore, as shown in FIG. 8, before the compressed air is inserted, at least a radius R of 1 mm, preferably a radius R of 2 mm or more is formed on the outer periphery of each joint 7 formed by the non-printing surface 5. The outer periphery of each joint 7 is formed into a curved shape without sharp corners so that the portion 36 is formed. Thus, when the inside of the composite plate 9 is expanded by the compressed air, the pressure is prevented from being dispersed as much as possible, and the problems that the joint 7 is peeled or the metal plates 1 and 2 are broken can be reliably prevented.
[0041]
Similarly, the boundary between the joint end 6 around the composite plate 9 and the non-joint 8 inside the composite plate 9 is also all curved without sharp corners. Therefore, in the present embodiment, at a stage before the compressed air is inserted, a corner R portion 37 having a radius R of at least 1 mm, preferably a radius R of at least 2 mm is formed on the outer periphery of the non-joined portion 8.
[0042]
The next step S5 is a vacuum layer forming step. FIG. 7 shows a state immediately after the completion of the vacuum layer forming step. In this step, the closed space 31 formed inside the composite plate 9 is degassed and depressurized by a vacuum pump (not shown) through the ventilation port 23, and then the tip of the metal pipe 22 is capped. Seal by welding or brazing. In FIG. 7, the welded portion 38 at the time of sealing closes the end opening of the metal pipe 22. Thus, a predetermined shape between the composite plates 9 is about 1 Torr (1 Torr = 133 Pa), preferably, 1.5 Torr to 0.1 Torr. The vacuum layer 15 having a degree of vacuum of 1 Torr (199.5 to 13.3 Pa) is formed. Alternatively, as another manufacturing method, the composite plate 9 may be placed in a decompression chamber, the vent hole 23 may be sealed, and the interior may be evacuated to vacuum. In a state where the vacuum layer 15 is formed, as shown in FIG. 7, the thickness (inner thickness) C of the vacuum layer 15 is about 3 mm, preferably 1 to 5 mm, and the total material thickness including the vacuum layer 15 is included. (Outer thickness) The composite plate 9 having excellent heat insulation and having D in the range of 4 mm, preferably 2 to 6 mm is obtained.
[0043]
Since the metal plates 1 and 2 forming the closed space 31 as the air layer therein are pressed and extended by the compressed air in the step S4, the metal plates 1 and 2 are hardened by work hardening, and the pressure of the deaeration and decompression is increased. The effect of preventing deformation can be obtained.
[0044]
By the way, a plurality of non-printing surfaces 5 for obtaining the joints 7 by rolling are formed at a predetermined interval, and after the metal plates 1 and 2 are expanded by injection of compressed air, the non-printed surfaces 5 are formed between the joints 7. Due to the beam strength of the metal plates 1 and 2, deformation of the metal plates 1 and 2 surrounding the expanded non-joined portion 8 (printed surface 3) is depressed when the internal pressure is reduced in the vacuum layer forming step of step S5. Is formed so as to suppress.
[0045]
The material thickness T before rolling is about 2 mm (preferably 1.2 to 2.8 mm), and A1050 or A1100 series aluminum plates are used as the base metal plates 1 and 2 and are quadrupled in the rolling process. After performing rolling (the thickness T ′ of the base material alone after rolling becomes about 0.5 mm) and further expanding the inside of the composite plate 9 with compressed air, the result of an internal decompression experiment shows that the inside is 1 Torr. When the distance L between the joints 7 was set to 5 mm, 8 mm, and 12 mm (24 times the material thickness T ′), there was no depression in the expanded metal plates 1 and 2. On the other hand, when the distance L between the joints 7 was set to 15 mm, 18 mm, and 23 mm (46 times the material thickness T ′) under the same conditions, the expanded metal plates 1 and 2 slightly dented, but the vacuum layer 15 Was formed to the extent that it could be formed. Further, when the distance L between the joints 7 is 27 mm (54 times the material thickness T ') and 30 mm, the recesses of the expanded metal plates 1 and 2 are large, and the two metal plates 1 and 2 come into contact with each other. Thus, it was difficult to form the final vacuum layer 15. From the above experimental results, the distance L between the non-joined portions 8 between the respective joined portions 7 is 50 times or less (L ≦ T ′ × 50) the thickness T ′ of the metal plates 1 and 2 after rolling, Preferably, it is set to 25 times or less (L ≦ T ′ × 50).
[0046]
Next, modifications of the above embodiment will be listed. As shown in FIG. 7, the total material thickness D including the vacuum layer 15 is preferably about 2 to 6 mm, but it is sufficient to select a thickness having a strength that does not deform due to internal pressure reduction. Although the pressure rolling has been described as a １ ／ thickness reduction, the degree of rolling may be arbitrarily selected according to the bonding strength of the metal plates 1 and 2. The thickness of the vacuum layer 15 may be selected according to the elongation (prevention of cutting) and heat insulation of the material, the required thickness of the composite plate 9 of the equipment to be used, and the like.
[0047]
In addition, the degree of vacuum inside the vacuum layer 15 has been described as about 1 Torr, but this may be appropriately set according to the required heat insulation performance of the equipment to be used.
[0048]
In addition, the pattern (pattern shape) of the printing surface 3 that determines the final shape of the vacuum layer 15 may be arbitrarily set according to the required heat insulating performance of the equipment to be used. For example, a non-printing surface 5 such as a dot or a line may be partially provided in the pattern of the printing surface 3, thereby providing a joint 7 for preventing deformation due to internal pressure reduction in the vacuum layer 15. However, when the area of the joint 7 between the vacuum layers 15 provided for improving the strength becomes large, the heat conduction by the joint 7 reduces the heat insulating effect. It is convenient in point.
[0049]
In some cases, the surface of the composite plate 9 as a composite may be subjected to rust-proofing treatment by using alumite or painting.
[0050]
By the way, in the vent forming process of the step S3, when the outer diameter φ2 of the metal pipe 22 constituting the vent 23 becomes large, the space between the metal plates 1 and 2 is expanded to the outer diameter φ2 of the metal pipe 22 or more, and the metal pipe 22 is expanded. Since the metal plate 22 must be inserted, not only the workability is deteriorated, but also the metal plates 1 and 2, which are base materials, may be broken. If the outer diameter φ2 of the metal pipe 22 is too large than the outer thickness C of the vacuum layer 15, a large space for accommodating the metal pipe 22 is provided when the composite plate 9 which is a heat insulating plate is mounted inside the device. Is required, which leads to an increase in the size of the device body. Therefore, it is preferable that the metal pipe 22 be as thin as possible. However, if the metal pipe 22 is too thin, there is a problem that it becomes difficult to inject compressed air or to perform a pressure reducing operation using a vacuum pump. Then, as a result of examining the outer diameter φ2 of the metal pipe 22, when the outer thickness D of the vacuum layer 15 including the metal plates 1 and 2 is 4 mm, the workability is best when the outer diameter φ2 is 5 to 9 mm. If the outer diameter φ2 is less than 5 mm, the time for injecting compressed air or reducing the pressure is long, and if the outer diameter φ2 is 10 mm or more, it is difficult to perform post-processing for moving to the space accommodating the metal pipe 22 (metal pipe 22 Becomes thick and difficult to bend).
[0051]
Therefore, the outer diameter φ2 of the metal pipe 22 is 10 mm or less, or 2.5 times or less the outer thickness D of the vacuum layer 15 (φ2 ≦ D × 2.5: If the outer thickness D is 4 mm, the outer diameter φ2 is 10 mm). It is preferred that When the metal pipe 22 is welded to the metal plates 1 and 2 and the metal pipe 22 is smaller than the inner thickness C of the vacuum layer 15, the metal pipe 22 and the metal plates 1 and 2 are attached when the metal pipe 22 is mounted. Therefore, the outer diameter φ2 of the metal pipe 22 is preferably equal to or larger than the inner thickness C of the vacuum layer 15 (φ2 ≧ C). Furthermore, the inner diameter φ3 of the metal pipe 22 is 3 mm or more in consideration of the pressure of the compressed air to be injected, the pressure at the time of pressure reduction, and the like.
[0052]
As described above, the joining end 6 on the outer periphery of the metal plates 1 and 2 preferably has a width W of 2 mm so that peeling or destruction does not occur when the composite plate 9 is expanded. When the composite plate 9 as the heat insulating plate obtained as described above is used by being wound around a container to be kept warm or a container to be kept cool provided in the main body of the apparatus by winding or the like, the vacuum at both ends of the composite plate 9 is used. When the composite plate 9 is wound around the layer 15, there is a problem that the overlapping portion becomes thick and it becomes difficult to store the composite plate 9 in the apparatus main body. If the composite plate 9 is used in a cylindrical state by actively widening the W and joining the joining ends 6, the thickness of the overlapping portion of the composite plate 9 can be suppressed, and the problem that the device body becomes large is prevented. it can.
[0053]
FIG. 9 shows a state after the composite plate 9 is bent. As described above, the composite plate 9 is wound into, for example, a cylindrical or rectangular tube shape in accordance with the shape of the place of use. FIG. 9 shows that four bent portions 39a, 39b, 39c, and 39d are formed at four corners by bending, and thereafter, the joining ends 6 formed at both ends of the composite plate 9 are overlapped to form a rivet 40. Is fixed by the following method.
[0054]
Further, in step S5, after the vacuum layer 15 is provided inside and the composite plate 9 serving as the final heat insulating material is processed, the surfaces of the metal plates 1 and 2 serving as the outer surfaces of the heat insulating material are subjected to electrolytic polishing, buff polishing, May be performed, or a glossy process resulting from the smoothed surface may be performed. As described above, by improving the smoothness of the surfaces of the metal plates 1 and 2, irregular reflection of electromagnetic waves (infrared rays) on the surfaces of the metal plates 1 and 2 is suppressed, and the absorption area of the electromagnetic waves is reduced. Thus, the reflectivity of the heat energy is increased, and the heat insulating property is further improved. In particular, when aluminum is used for the metal plates 1 and 2, since aluminum is originally a material having a higher heat energy reflection efficiency than stainless steel, the heat insulating property can be further improved.
[0055]
Next, application of the composite board 9 obtained as described above to various devices will be described. FIG. 10 is a schematic diagram showing a vertical cross section of a boiling water device such as an electric kettle for boiling water to keep the temperature warm, a rice cooker for cooking and keeping the rice warm, or a jar for keeping the rice warm. Reference numeral 51 denotes a main body of the water heater, and 52 denotes a lid that covers an upper opening of the main body. The outer shell of each of these members is formed of resin or the like. Inside the main body 51, a container 53 for accommodating an object to be heated is provided. The container 53 is made of stainless steel, and has an inner surface coated with a fluororesin to form a coating film 54. The coating film 54 is formed to improve the corrosion resistance of the container 53, and the coating film 54 may be formed of a heat-resistant resin other than a fluororesin, for example, a silicone resin. Also, the container 53 may be made of metal other than stainless steel, for example, aluminum. The lower surface 52a of the lid 52 facing the container 53 is made of a metal plate such as stainless steel. Further, the container 53 is formed in a container shape by welding and joining the side surface portion 53a and the bottom surface portion 53b at the welding portion 53c.
[0056]
An electric heater 55 serving as a heating unit is provided below the bottom 53b of the container 53. The electric heater 55 heats the bottom of the container 53. Note that the heating means may be configured by a heating coil for electromagnetic induction instead of the electric heater 55. When the heating means is constituted by a heating coil, at least a part of the container 53 is constituted by a magnetic metal which generates heat by electromagnetic induction, facing the heating coil. With this configuration, when a high-frequency current is supplied to the heating coil, the magnetic metal portion of the container 53 generates heat due to the alternating magnetic field from the heating coil, and the container 53 can be directly heated.
[0057]
The composite plate 9 formed of the above-described aluminum plate is provided around the container 53. A composite plate 9a is provided on the side surface 53a of the container 53 in a non-contact and close proximity. That is, a gap 58 is formed between the composite plate 9a and the side surface 53a of the container 53. The reason for disposing the composite plate 9a in a non-contact manner is that aluminum has a low heat radiation but a good thermal conductivity, so that the aluminum composite plate 9 is placed in contact with the container 53 which is a heat-retaining member. This is because heat of the container 53 is easily released by heat conduction, and the heat insulating property is reduced. The dimension of the gap 58 is preferably 0.5 to 9 mm where a still air layer is formed, and if it is larger than this, heat convection occurs in the gap 9 and the heat insulating property is reduced.
[0058]
In the case where the container 53, which is the object to be kept warm, is made of stainless steel, the container itself is stainless steel and emits a large amount of heat. However, the aluminum metal plates 1 and 2, which are the outer members of the composite plate 9, have heat reflection properties. Since it is good, the heat radiated from the container 53 is reflected by the composite plate 9 on the outside thereof, and the extremely effective heat insulating effect of the container 53 can be obtained with the vacuum heat insulating property of the composite plate 9. Further, when a coating film 54 of fluorine or silicone is formed on the inner surface of the stainless steel container 53, a temper collar is generated on the outer surface of the container 53 at the time of coating and drying, and this promotes heat radiation. The characteristics of the composite plate 9 make it possible to obtain an effective heat insulating structure. Further, by disposing the composite plate 9a in a non-contact manner, electric corrosion between different metals (stainless steel and aluminum) can be prevented.
[0059]
In addition, a composite plate 9b is provided below and close to the outside of the electric heater 55 in a non-contact manner, and a composite plate 9c is provided above and below the lower surface 52a of the lid 52 in a non-contact manner. That is, a gap 59 is formed between the composite plate 9b and the lower surface of the electric heater 55, and a gap 60 is also formed between the composite plate 9c and the lower surface 52a of the lid 52.
[0060]
The composite plate 9 (9a, 9b, 9c) is formed by joining two aluminum metal plates 1 and 2, and has a vacuum layer 15 (15a, 15b, 15c) inside. I have. As described above, the container 53 is surrounded and covered by the composite plate 9 from the four sides, the bottom surface, and the top surface, and since the composite plate 9 is kept in a non-contact state with the container 53, the heat of the container 53 is reduced. Is reliably prevented from radiating to the outside.
[0061]
In the case where the boiling device has a structure in which a container 53 such as a rice cooker can be attached to and detached from the main body 51, a concave container housing portion for housing the container 53 which is a pot is provided in the main body 51, and an outer periphery of the container housing portion is provided. A composite plate 9 may be provided. Further, a heating means is provided at the bottom of the container 53, and a composite plate 9b is provided below the outside of the heating means. In addition, when the heating means is arranged on the side of the container 53 or the container accommodating portion, it is preferable to arrange the composite plate 9a outside the heating means. Further, a heating means may be arranged inside the lid 2, but also in this case, it is preferable to arrange the vacuum heat insulating plate 6 outside the heating means. In any case, in order to secure a gap between the composite plate 9 and the heating means, it is preferable to provide the composite plate 9 at a desired position in a non-contact state as much as possible, although unavoidable point-like or linear contact is required.
[0062]
Further, when the above-described heating coil for electromagnetic induction is used as the heating means, if the composite plate 9b is arranged outside the heating coil, the material of the composite plate 9b is aluminum having a magnetic-shielding effect. Can be prevented, and the heating efficiency of the container 53 can be improved.
[0063]
As another example, if the composite plate 9 is provided on the outer surface of the inside of the oven of the microwave oven, the heating efficiency can be improved during oven cooking and energy can be saved. Further, if the composite plate 9 is provided on the lower surface of the hot plate, the temperature of the table surface can be suppressed from rising, so that the surface of the hot plate can be set lower than before. Further, in the electromagnetic induction stove, if the composite plate 9 is provided below the heating means, the magnetic shielding effect of the metal plates 1 and 2 made of aluminum can improve the heating efficiency and prevent the leakage of magnetic flux to the floor. In this way, it is possible to contribute to the improvement of the heat insulating property, the heat insulating property and the anti-magnetic property, and the energy saving property of various heating and heat retaining devices.
[0064]
FIG. 11 shows an example of application to a refrigerator. In the figure, reference numeral 61 denotes a main body that forms a refrigerator interior 62 that is a cold storage container, 63 denotes an openable and closable door that closes a front opening of the refrigerator interior 62, and a heat constituting a refrigeration cycle is provided behind the refrigerator interior 62. An exchanger 64 and a cooling means 65 are arranged. Reference numeral 66 denotes a cool air radiator provided in the refrigerator 62, from which cool air is radiated to the refrigerator 62. The above-described composite plate 9 is provided on the ceiling surface, the bottom surface, and the outer surface (the rear surface and both side surfaces) of the inside 62 of the refrigerator, and is also provided inside the door 63. I have. These heat insulating plates 9 block heat from the outside of the refrigerator to the inside 62 of the refrigerator, and keep the coolness of the inside 62 good. The present invention is not limited to the refrigerator, and can be similarly applied to other cool devices such as a wine cooler.
[0065]
Note that a large composite board 9 is required for a large device such as a refrigerator. In this case, a plurality of divided composite boards 9 may be incorporated. When the composite plate 9 is used for heat insulation such as in a drying oven or a boiler, the composite plate 9 may be incorporated as a heat insulating shielding member at a high-temperature portion where there is a possibility of contact with humans.
[0066]
FIG. 12 shows an example in which the composite plate 9 is used as a reflector of a heating unit. In the same figure, reference numeral 71 denotes an electric heater as a heating means, and 72 denotes a heated object mounted on a base 73 heated by the electric heater 71, on the opposite side of the heated object 72 across the electric heater 71. A composite plate 9 as a reflection plate is arranged. In this case, the outer members (metal plates 1 and 2) of the composite plate 9 are made of aluminum having good heat reflectivity. The radiant heat of the electric heater 71 goes directly to the object to be heated 72, and the radiant heat reflected by the composite plate 9 also goes to the object to be heated 72. Therefore, the object to be heated 72 can be heated more efficiently. In addition, a rise in the temperature of the outer surface of the composite plate 9 where the electric heater 71 is not provided is suppressed. For example, when applied to a drying oven, the temperature of the outer casing of the apparatus can be reduced, and safety is improved. The efficiency of heating the heating element 71 is also improved.
[0067]
As described above, in the method of manufacturing a heat insulator according to the present embodiment, printing is performed on the surfaces of the metal plates 1 and 2 made of, for example, aluminum, and a plurality of metal plates 1 and 2 are stacked with the printed surface 3 as an inner surface. The non-printing surfaces 4 and 5 between the metal plates 1 and 2 are joined by rolling and rolling, and an opening 21 communicating with the outside air is provided on the printing surface 3. , 2 is formed by the printing surface 3, and then the closed space 31 is degassed from the opening 21 to form the reduced pressure vacuum layer 15, and the opening 21 is closed by, for example, welding. I have.
[0068]
In this case, since the printing surfaces 4 and 5 of the plurality of superposed metal plates 1 and 2 are joined by rolling, the joining reliability is high, and the joining portions (joining ends) formed by the non-printing surfaces 4 and 5 are formed. It is also difficult to form a gap between the portion 6 and the joint 7). In addition, since the formation of the closed space 31 when forming the vacuum layer 15 is not by welding but by rolling, the processing is easy, the sealing reliability is high, and the heat insulating effect of the vacuum layer 15 is ensured for a long time. be able to. Further, the vacuum layer 15 can be formed in any shape by appropriately applying the printing surface 3 to the surfaces of the metal plates 1 and 2 in a pattern. Therefore, it can be formed into an arbitrary and complicated shape other than a fixed pattern such as a square or a circle, depending on the device using the heat insulator. In addition, since there is no holding member such as silica powder inside the heat insulator, there is no need to disassemble and separate the inside when disposing the heat insulator, and if the metal plates 1 and 2 are dissolved, recycling is easy.
[0069]
If aluminum is selected as the material of the metal plates 1 and 2, the weight can be reduced as compared with a heavy metal such as stainless steel, and it can be easily incorporated into a large-sized device. Also, aluminum emits less heat radiation from the outer surface than stainless steel, so that heat insulation can be further improved.
[0070]
Furthermore, when using a heat insulator surrounding a stainless steel container or pot, the heat insulator does not release heat even if the outer surface of such a container or pot generates a temper color due to painting or the like. As a result, the heat insulation can be prevented from being adversely affected.
[0071]
In such a manufacturing method, it is preferable to select the material of the metal plates 1 and 2 from any of aluminum, stainless steel, titanium or an alloy thereof, and to form a plurality of joints 7 by rolling.
[0072]
In this case, the required heat insulating performance and the installation environment of the heat insulator are different for each device using the heat insulator, and the materials of the metal plates 1 and 2 suitable for such heat insulation performance and the installation environment are changed to aluminum, stainless steel, titanium, and the like. Alternatively, it can be arbitrarily selected from alloys thereof. For example, in a high-temperature and high-humidity environment, stainless steel excellent in corrosion resistance is selected, and when lightness is required, titanium is selected. If it is necessary to use the heat-insulated container in contact with the heat-insulated container, the same material as the heat-insulated container is selected to prevent electrolytic corrosion. Further, since stainless steel has lower thermal conductivity than aluminum, if the heat insulator has thermal conductivity, stainless steel having low thermal conductivity is selected. Also, when the heat insulator is used also as an outer member of the equipment, if strength and hardness are required, stainless steel is selected. Further, titanium can be selected to prevent metal allergy.
[0073]
In addition, if a plurality of joints 8 are formed by rolling, deformation of the non-joined parts 8 of the metal plates 1 and 2 expanded at the time of deaeration and decompression due to the beam strength between the metal plates 1 and 2 of the joint 7. Can be suppressed. Therefore, at the time of processing the vacuum layer 15, it is possible to eliminate the problem that the volume of the sealed space 31 that is once expanded and formed is reduced, and the heat insulation performance is reduced. Further, in order to prevent such deformation, the thickness of the metal plates 1 and 2 need not be increased, and the weight of the entire heat insulator does not increase.
[0074]
In particular, even when aluminum, which is considered to have relatively low strength, is selected as the material of the metal plates 1 and 2, the vacuum layer 15 can be formed by suppressing deformation of the metal plates, and is lightweight and excellent in heat insulation. A vacuum heat insulator can be formed.
[0075]
Further, in such a manufacturing method, a plurality of joints 7 are formed by rolling, and a distance between the joints 7 is set to within 50 times the material thickness T ′ of the metal plates 1 and 2 after the rolling, The area S of each joint 7 is 5 mm 2 In addition to the above, it is preferable that the outer periphery of each of the joining portions 1 and 2 is formed in a curved shape such as the corner R portion 36.
[0076]
As described above, if the distance between the plurality of joints 7 is selected within the optimal 50 times based on the results of the previous experiment, the reexamination will be made even when a new design of a heat insulator of various shapes is made. Deformation of the expanded metal plates 1 and 2 during deaeration and decompression can be prevented without bothering. This makes it possible to manufacture a light-weight heat insulator having the vacuum layer 15 having desirable heat-insulating performance without interposing another holding member such as silica powder inside the heat insulator.
[0077]
On the other hand, in order to use the heat insulating layer of the vacuum layer 15 efficiently, it is necessary to reduce the heat conduction between the metal plates 1 and 2 as much as possible. For that purpose, it is preferable to reduce the area S of the joint 7. However, if the area S is too small and the metal plates 1 and 2 are broken due to the separation of the joint 7 when the compressed air 31 is inserted, a fatal problem that the vacuum layer 15 itself cannot be formed may occur. Occurs. Therefore, based on the results of empirically verifying such contradictory problems, the area S of each joint 7 is set to 5 mm. 2 If the outer periphery of each joint 7 is formed in a curved shape as described above, it is possible to reliably prevent the joint 7 from peeling or the metal plates 1 and 2 from breaking when the compressed air 31 is injected.
[0078]
Further, in such a manufacturing method, a joining end portion 6 formed by rolling on the outer periphery of the plurality of metal plates 1 and 2 is formed to have a width W of 2 mm or more, and the joining end portions 6 are overlapped to form a heat insulator. Preferably, it is formed in a cylindrical shape.
[0079]
In order to efficiently use the heat insulating layer of the vacuum layer 15, it is necessary to minimize the heat conduction between the metal plates 1 and 2, and for that purpose, it is preferable to reduce the area of the joint end 6, Conversely, if the area is too small, and the metal plates 1 and 2 are broken due to the separation of the joint end 6 when the compressed air 31 is inserted, a fatal problem will occur in that the vacuum layer 15 itself cannot be formed. Therefore, based on the results of an experiment that proved such contradictory problems, the joint end portion 7 formed on the outer periphery between the plurality of metal plates 1 and 2 by rolling has a width W of 2 mm or more. When the air 31 is injected, it is possible to reliably prevent the joint end 6 from peeling or the metal plates 1 and 2 from being broken.
[0080]
When the completed composite plate 9 as a heat insulator is wound around the outside of a container of an apparatus such as an electric pot and mounted, for example, the vacuum layers 15 and the vacuum layer 15 and the joining end 6 are overlapped to form a composite. When the end of the plate 9 is processed, the thickness of the overlapped portion is increased by the amount corresponding to the vacuum layer 15, and there is a problem that the device body accommodating the composite plate 9 becomes large. If the plate 9 is wound, the composite plate 9 does not become unnecessarily thick, and the device body does not need to be made unnecessarily large. In addition, since the vacuum layer 15 does not exist in the overlapped portion, if the overlapped portion is fixed with a fastener such as a rivet and the tubular composite plate 9 is formed in advance, the mountability to a container or the like can be improved.
[0081]
In addition, in such a manufacturing method, it is preferable to additionally perform a post-processing step of finishing the outer surfaces of the metal plates 1 and 2 with a smooth or glossy surface after closing the opening 21.
[0082]
In this case, the outer surfaces of the metal plates 1 and 2 are finished with a smooth surface or a glossy surface, so that the reflectivity of electromagnetic waves (infrared rays) is improved. Absorption can be suppressed, and the heat insulating effect of the composite board 9 can be further enhanced. The appearance is also improved when the composite plate 9 is exposed to the outside.
[0083]
Further, in the manufacturing method in this embodiment, printing is performed on the surfaces of the metal plates 1 and 2, the plurality of metal plates 1 and 2 are overlapped with the printed surface 3 as an inner surface, and the metal plates 1 and 2 are rolled. The printing surface 3 is provided with an opening 21 communicating with the outside air, and the opening 21 is joined with a metal pipe 22 as a cylindrical body of the same material as the metal plate 3. The sealed space 31 expanded by the printing surface 3 between the metal plates 1 and 2 is formed by inserting compressed air, and then the closed space 31 is evacuated from the metal pipe 22 to form the reduced pressure vacuum layer 15. The metal pipe 22 has an outer diameter φ2 of not less than the inner thickness C of the vacuum layer 15 and not more than 10 mm or not more than 2.5 times the outer thickness D of the vacuum layer 15.
[0084]
Further, a metal pipe 22 made of the same material as the metal plates 1 and 2 is joined to the mouth portion 21 by welding or the like, and compressed air is inserted from the cylindrical body, and at a portion which becomes the non-joined portion 8 corresponding to the printing surface. After forming the expanded closed space 31 and then evacuating the air from the metal pipe 22 to reduce the pressure in the closed space to form the vacuum layer 15, the metal pipe 22 is closed by welding or the like to obtain a desired composite plate. 9 can be obtained. Therefore, the internal expansion between the metal plates 1 and 2 and the decompression of the closed space 31 can be shared by the common metal pipe 22, and the workability can be improved rationally.
[0085]
In addition, by setting the outer diameter of the metal pipe 22 to 10 mm or less or 2.5 times or less the outer thickness of the vacuum layer 15, there is no obstacle to the injection of the compressed air 31 or the deaeration between the metal plates 1 and 2. At the same time, by making the opening area of the metal pipe 22 as small as possible, welding sealing at the end opening of the metal pipe 22 becomes easy. Furthermore, even when the composite board 9 is housed inside the device, the space for accommodating the metal pipe 22 is reduced as much as possible to prevent the device from being enlarged, and the metal pipe 22 is positioned in the space for accommodating the metal pipe 22. Bending and crushing can be performed without any trouble.
[0086]
Further, by setting the outer diameter of the metal pipe 22 to be equal to or larger than the inner thickness of the vacuum layer 15, the injection of compressed air and the deaeration operation between the metal plates 1 and 2 can be carried out smoothly, When the metal pipes 1 and 2 are inserted, a gap with the metal plates 1 and 2 hardly occurs, and the metal pipe 22 can be easily joined to the metal plates 1 and 2 made of the same material by welding or the like.
[0087]
Further, the heat insulator in this embodiment is printed on the surfaces of the metal plates 1 and 2 made of pure aluminum having a material thickness T of 1.2 to 2.8 mm and a purity of 99% or more, and the printed surface 3 is used as an inner surface. A plurality of metal plates 1 and 2 are overlapped, and the area S of each joint 7 is about 12 mm 2 The non-printed surface between the metal plates 1 and 2 is rolled approximately four times so that the distance L between the joints 7 is within 15 mm and the metal plates 1 and 2 have a material thickness of 1/4. 5 is provided, an opening 21 communicating with the outside air is provided on the printing surface 3, and compressed air of 60 to 120 Pa is inserted through the opening 21 so that the material thickness D including the metal plates 1 and 2 is about 4 mm. A sealed space 31 having a thickness of about 3 mm expanded by the printing surface 3 between the metal plates 1 and 2 is formed, and then the inside of the sealed space 31 is degassed from the mouth 21 to reduce the pressure of the sealed space 31. It is formed as a vacuum layer 15 having a degree of vacuum, and is manufactured by closing the opening 21.
[0088]
In this case, since the printing surfaces 4 and 5 of the plurality of superposed metal plates 1 and 2 are joined by rolling, the joining reliability is high, and the joining portions (joining ends) formed by the non-printing surfaces 4 and 5 are formed. It is also difficult to form a gap between the portion 6 and the joint 7). In addition, since the formation of the closed space 31 when forming the vacuum layer 15 is not by welding but by rolling, the processing is easy, the sealing reliability is high, and the heat insulating effect of the vacuum layer 15 is ensured for a long time. be able to. Further, the vacuum layer 15 can be formed in any shape by appropriately applying the printing surface 3 to the surfaces of the metal plates 1 and 2 in a pattern. Therefore, it can be formed into an arbitrary and complicated shape other than a fixed pattern such as a square or a circle, depending on the device using the heat insulator. In addition, since there is no holding member such as silica powder inside the heat insulator, there is no need to disassemble and separate the inside when disposing the heat insulator, and if the metal plates 1 and 2 are dissolved, recycling is easy.
[0089]
Further, pure aluminum having a material thickness T of 1.2 to 2.8 mm is selected as the metal plates 1 and 2, and the area S of each joint 6 is about 12 mm. 2 Then, the distance L between the joints 6 was set to 15 mm or less, the metal plates 1 and 2 were rolled about four times, and compressed air of 60 to 120 Pa was inserted from the mouth 21 to include the metal plates 1 and 2. If the closed space 31 having a thickness of about 3 mm is formed so that the material thickness D is about 4 mm, the metal plates 1 and 2 as base materials may be broken when the inside of the metal plates 1 and 2 is expanded. Can be prevented, and the sealed space 31 serving as the vacuum layer 15 can be reliably formed.
[0090]
Further, in the case of the metal plates 1 and 2 made of aluminum, if a vacuum layer having an internal vacuum degree of 199.5 Pa or less, preferably about 133 Pa or less is formed, heat insulation as the vacuum layer 15 can be secured. Conversely, when the degree of vacuum increases, deformation of the metal plates 1 and 2 tends to occur at the place where the closed space 31 is formed at the time of decompression. However, if the degree of vacuum is 13.3 Pa or more, such deformation can be prevented, and It is possible to manufacture a lightweight composite plate 9 having a vacuum volume and excellent heat insulation properties.
[0091]
It should be noted that the present invention is not limited to the above embodiment, and can be appropriately modified within the scope of the present invention.
[0092]
【The invention's effect】
According to the method for manufacturing a heat insulator according to the first aspect of the present invention, a vacuum layer can be obtained by simply processing the vacuum layer in an arbitrary shape, and a heat insulator having excellent heat insulating properties and recyclability can be obtained.
[0093]
According to the method for manufacturing a heat insulator according to the second aspect of the present invention, it is possible to arbitrarily select a metal material suitable for heat insulation performance and an installation environment. In addition, it is possible to eliminate the problem of lowering the heat insulation performance when processing the vacuum layer without increasing the thickness of the metal body.
[0094]
According to the method for manufacturing a heat insulator according to claim 3 of the present invention, a lightweight heat insulator having a vacuum layer having desirable heat insulating performance can be manufactured. In addition, it is possible to reliably prevent the joint from peeling off or the metal body from being broken when air is injected.
[0095]
According to the method of manufacturing a heat insulator according to claim 4 of the present invention, when the heat insulator is wound, the heat insulator does not become unnecessarily thick, and the mountability to a container or the like can be improved.
[0096]
According to the method for manufacturing a heat insulator according to claim 5 of the present invention, the heat insulating effect of the heat insulator can be further enhanced, and the appearance can be improved when the heat insulator is exposed to the outside.
[0097]
According to the method for manufacturing a heat insulator according to claim 6 of the present invention, a vacuum layer can be easily processed into a free shape and obtained, and a heat insulator excellent in heat insulation and recycling properties can be obtained. In addition, the common cylindrical body can be used for both internal expansion between metal bodies and decompression of space, which can be rational and improve workability. Further, degassing and depressurization between the metal bodies, welding and sealing at the end opening, bending and crushing of the cylinder can be performed without any trouble.
[0098]
According to the method for manufacturing a heat insulator according to claim 7 of the present invention, a vacuum layer can be easily processed into a free shape and can be obtained, and a heat insulator excellent in heat insulation and recyclability can be obtained. In addition, when expanding the inside of the metal body, it is possible to prevent the metal body, which is the base material, from being broken, to reliably form a space serving as a vacuum layer, and to ensure heat insulation as the vacuum layer.
[Brief description of the drawings]
FIG. 1 is a flowchart showing each step of a method for manufacturing a heat insulator in a preferred embodiment of the present invention.
FIG. 2 is a plan view showing a state in which silk printing has been performed on a metal plate before rolling.
FIG. 3 is a front view showing a state in which two metal plates before rolling are overlapped with each other;
FIG. 4 is a cross-sectional view of the composite plate obtained after the rolling process.
FIG. 5 is a plan view of the composite plate after the outer shape is removed after rolling.
FIG. 6 is a cross-sectional view after the compressed air is injected from the vent.
FIG. 7 is a cross-sectional view of the composite plate immediately after the completion of the vacuum layer forming step.
FIG. 8 is an enlarged view of a main part in FIG. 5;
FIG. 9 is a cross-sectional view and a side view of the composite plate after bending.
FIG. 10 is a schematic view of a longitudinal section of a water heater incorporating the composite plate according to the third embodiment.
FIG. 11 is a schematic cross-sectional view of a refrigerator incorporating the composite plate according to the first embodiment.
FIG. 12 is a side view in which the composite plate is applied as a reflector of an electric heater.
[Explanation of symbols]
1, 2 metal plate (metal body)
4,5 Non-printing side (non-printing part)
6 joining end (end)
7 Joint
15 vacuum layer
21 mouth
22 Metal pipe (tubular body)
31 Closed space (space)

Claims (7)

印刷を施し、金属体を接触させ、非印刷部を接合し、口部を設け、空間を形成し、脱気して前記空間を減圧した真空層として形成し、前記口部を閉塞したことを特徴とする断熱体の製造方法。Applying the printing, contacting the metal body, joining the non-printed part, providing a mouth, forming a space, forming a vacuum layer by degassing and depressurizing the space, and closing the mouth. A method for manufacturing a heat insulator. 前記金属体はアルミニウム，ステンレス，チタンまたはその合金などのいずれかからなると共に、接合部を複数形成したことを特徴とする請求項１記載の断熱体の製造方法。2. The method according to claim 1, wherein the metal body is made of any one of aluminum, stainless steel, titanium, and an alloy thereof, and a plurality of joints are formed. 接合部を複数形成し、接合部間を厚さの所定倍数以内とし、面積を約５ｍｍ２以上とすると共に、前記接合部を曲線状に形成したことを特徴とする請求項１または２記載の断熱体の製造方法。The joint according to claim 1 or 2, wherein a plurality of joints are formed, the distance between the joints is within a predetermined multiple of the thickness, the area is about 5 mm 2 or more, and the joints are formed in a curved shape. A method of manufacturing a heat insulator. 端部を形成し、この端部どうしを接触させて前記断熱体を筒状に形成することを特徴とする請求項１〜３のいずれか一つに記載の断熱体の製造方法。The method for manufacturing a heat insulator according to any one of claims 1 to 3, wherein an end portion is formed, and the end portions are brought into contact with each other to form the heat insulator into a cylindrical shape. 前記口部を閉塞した後、前記金属体を平滑または光沢仕上げしたことを特徴とする請求項１〜４のいずれか一つに記載の断熱体の製造方法。The method for manufacturing a heat insulator according to any one of claims 1 to 4, wherein the metal body is smoothed or gloss-finished after closing the opening. 印刷を施し、金属体を接触させ、非印刷部を接合し、口部を設け、筒体を接合し、空間を形成し、脱気して前記空間を減圧した真空層として形成し、前記筒体を閉塞すると共に、前記筒体は前記真空層の内厚以上で、所定値以下または外厚の所定倍数以下の径を有することを特徴とする断熱体の製造方法。Applying printing, contacting the metal body, joining the non-printed part, providing the mouth, joining the cylinder, forming a space, deaerated and forming the space as a depressurized vacuum layer, the cylinder A method of manufacturing a heat insulator, comprising closing a body and having a diameter equal to or greater than an inner thickness of the vacuum layer and equal to or less than a predetermined value or a predetermined multiple of an outer thickness. 金属体に印刷を施し、金属体を接触させ、接合部の面積が約１２ｍｍ２で、接合部間が所定値以内となり、且つ所定厚さになるように加工して、非印刷部を接合し、口部を設け、気体を挿入して、厚さが所定値となるように空間を形成し、脱気して減圧した所定の真空度を有する真空層として形成し、前記口部を閉塞したことを特徴とする断熱体の製造方法。By printing the metal body is brought into contact with the metal body, in the area of the junction of about 12 mm 2, junction part becomes within a predetermined value, and processed to to a predetermined thickness, joining the non-printing portion , An opening was provided, a gas was inserted, a space was formed so that the thickness became a predetermined value, and a space was formed as a vacuum layer having a predetermined degree of vacuum degassed and decompressed, and the opening was closed. A method for producing a heat insulator.
JP2003045037A 2003-02-21 2003-02-21 Manufacturing method for heat insulator Pending JP2004251428A (en)

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63187084A (en) * 1986-10-08 1988-08-02 ユニオン・カーバイド・コーポレーション Vacuum heat-insulating panel
JPH02120598A (en) * 1988-10-31 1990-05-08 Matsushita Refrig Co Ltd Insulating body
JPH02147124A (en) * 1988-09-09 1990-06-06 British Aerospace Plc <Baf> Domed structure and manufacture thereof
JPH04309779A (en) * 1991-04-09 1992-11-02 Sharp Corp Manufacture of vacuum heat insulating material
JPH07158791A (en) * 1993-12-10 1995-06-20 Meisei Kogyo Kk Manufacture of vacuum heat insulated structure
JPH0868591A (en) * 1994-08-29 1996-03-12 Toshiba Corp Heat-insulating box
JPH0914575A (en) * 1995-06-23 1997-01-17 Masaki Murakami Heat insulating plate or heat insulating film
JPH1068569A (en) * 1996-08-27 1998-03-10 Matsushita Electric Works Ltd Cold/hot storeroom
JP2000161588A (en) * 1998-11-20 2000-06-16 Matsushita Electric Ind Co Ltd Composite heat insulating material
JP2002369747A (en) * 2001-06-13 2002-12-24 Zojirushi Corp Electric water heater

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63187084A (en) * 1986-10-08 1988-08-02 ユニオン・カーバイド・コーポレーション Vacuum heat-insulating panel
JPH02147124A (en) * 1988-09-09 1990-06-06 British Aerospace Plc <Baf> Domed structure and manufacture thereof
JPH02120598A (en) * 1988-10-31 1990-05-08 Matsushita Refrig Co Ltd Insulating body
JPH04309779A (en) * 1991-04-09 1992-11-02 Sharp Corp Manufacture of vacuum heat insulating material
JPH07158791A (en) * 1993-12-10 1995-06-20 Meisei Kogyo Kk Manufacture of vacuum heat insulated structure
JPH0868591A (en) * 1994-08-29 1996-03-12 Toshiba Corp Heat-insulating box
JPH0914575A (en) * 1995-06-23 1997-01-17 Masaki Murakami Heat insulating plate or heat insulating film
JPH1068569A (en) * 1996-08-27 1998-03-10 Matsushita Electric Works Ltd Cold/hot storeroom
JP2000161588A (en) * 1998-11-20 2000-06-16 Matsushita Electric Ind Co Ltd Composite heat insulating material
JP2002369747A (en) * 2001-06-13 2002-12-24 Zojirushi Corp Electric water heater

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