JP4511797B2 - Internal grooved tube, manufacturing apparatus thereof, and manufacturing method thereof - Google Patents

Description

【００８４】
【表２】

【００８５】
表１の結果より、本発明の実施例１、２、及び参考例１〜３のいずれもが、内面溝付管内の製造可否（加工性）及び伝熱性能が共に満足する結果となった。
【００８６】
比較例１より、フィン根元半径Ｒが下限値未満であると内面溝付管の製造は不可であり、比較例２より、フィン根元半径Ｒが上限値を超えると管内の伝熱性能は満足しないことから、フィン根元半径Ｒが範囲内から逸れると、内面溝付管の生産性及び管内伝熱性能のいずれも満足しない。また、比較例３より、フィンピッチＬが上限値を超えると管内の伝熱性能は満足せず、比較例４よりフィンピッチＬが下限値０．２ｍｍ未満であると、内面溝付管の製造は不可であることから、フィンピッチＬが範囲内から逸れると、内面溝付管の生産性及び管内伝熱性能のいずれも満足しない。さらに、比較例５より、フィン根元半径ＲとフィンピッチＬの比Ｒ／Ｌが下限値未満であると製造は可能であるが、管内の伝熱性能は満足せず、比較例６より、フィン根元半径ＲとフィンピッチＬの比Ｒ／Ｌが上限値を超えると内面溝付管の製造は不可であることから、フィン根元半径ＲとフィンピッチＬの比Ｒ／Ｌが範囲内から逸れると、内面溝付管の生産性及び管内伝熱性能のいずれも満足しない。
【００８７】
比較例７より、フィン根元半径Ｒ、及び溝リード角θが下限値未満であると、内面溝付管の製造は可能であるが、管内の伝熱性能は満足しない。また、比較例８より、フィン高さＨが下限値未満であると、管内の伝熱性能は満足せず、比較例９より、フィン高さＨが上限値を超えると、内面溝付管の製造は不可であることから、フィン高さＨが範囲内から逸れると、内面溝付管の生産性及び管内伝熱性能のいずれも満足しない。さらに、比較例１０より、フィン山頂角αが下限値未満であると、内面溝付管の製造は不可であり、比較例１１より、フィン山頂角αが上限値を超えると、管内の伝熱性能は満足しないことから、フィン山頂角αが範囲内から逸れると、内面溝付管の生産性及び管内伝熱性能のいずれも満足しない。
【００８８】
フィン根元半径Ｒ、フィンピッチＬ、フィン根元半径とフィンピッチの比Ｒ／Ｌのいずれか１つでも、本発明の請求範囲から逸れた場合は、内面溝付管の加工性あるいは管内伝熱性能のいずれかが満足しない結果であった。
【００８９】
（第２の実施例）
次に、素管の製造条件である平均結晶粒径、０．５％耐力、及び伸びと、製造された素管の第１の縮径加工による０．５％耐力の増加率及び第３の縮径加工による外径変化率の全てが、本発明の請求範囲を満足する試作管（実施例６〜８）と、前記４つのうち３つまたは全てが本発明の請求範囲を満足しない試作管（比較例１２〜１５）をそれぞれ作製した。内面溝加工を行う素管の製造法は、直径３００ｍｍのＣ１２２０鋳塊（P：０．０２２％）より複数の押出し用ビレットを切出し、前記ビレットを８００〜９００°Cで３０分程度均質化焼鈍後、８００〜９００°Cで熱間押出し、シャワー水冷（平均冷却速度１０〜１５°C／秒）することにより押出素管を作製した。
【００９０】
押出素管に、圧延、抽伸加工を行って外径９．５２ｍｍ、肉厚０．５ｍｍの素管とした後、焼鈍により内面溝付加工用の素管とした。前記の焼鈍には、高周波誘導加熱炉（高速昇温、短時間高温加熱、急速冷却）、またはローラーハース炉（低速昇温、４５０〜５５０°C×３０分〜１時間加熱、徐冷）を用い平均結晶粒径、０．５％耐力、伸びの異なる内面溝付加工用素管のコイルを作製した。平均結晶粒径は、ＪＩＳＨ０５０１に規定の切断法により管軸平行断面について測定した。
【００９１】
また、０．５％耐力及び伸びはＪＩＳＺ２２４１に規定の方法により求めた。
そして、作製した素管コイルに表３に示す条件を有する溝付プラグを用いて内面溝付加工を行い、長さ５００ｍの内面溝付管を作製した（引抜き速度３０ｍ／秒）。尚、内面溝付管の製造に用いた縮径ダイス及び整形ダイスは、実施例６〜８、及び比較例１２〜１５の全ての試作管に対し、同一の物とし、整形部（整形ダイス）による第３の縮径加工は、管の外径変化率１０％で行った。
【００９２】
また、作製された内面溝付管は、外径が７．０ｍｍ、溝リードθ角が約４２°、フィン高さＨが０．２ｍｍ、溝数が６５、フィンピッチが０．３ｍｍ、フィン根元半径Ｒが０．０８ｍｍ、フィン根元半径とフィンピッチとの比Ｒ／Ｌが０．２７である。この内面溝付管の定常加工部（引抜き速度が所定値に安定した部分）の先端部及び後端部より試料を採取して断面を観察して溝の成形状況を観察した。
【００９３】
次に、所定の形状の溝が形成されている試料は残りのコイルをローラーハース炉で所定条件のもとで焼鈍後、コイルの両端より試料を採取して管軸平行断面の組織を観察し、再結晶の様子（混粒の発生状況）を調査した。各試作管について、素管の平均結晶粒径、０．５％耐力及び伸び、製造可否（フィンの成形性）、工具である溝付プラグの欠損有無、及び混粒組織の有無を表４に示す。
【００９４】
【表３】

【００９５】
【表４】

【００９６】
表４の結果より、本発明の実施例６、７、及び８のいずれもが、所定形状の溝が形成された内面溝付管を、プラグの欠けを発生させることなく製作することが可能であった。また、焼鈍後も混粒組織となることがなく（平均結晶粒径２０μｍ）、熱交換器組立てのためにＵベント曲げを行っても曲げ部のしわ、割れなどの不具合が発生せず、歩留まり良く熱交換器に組み立てることが可能であった。
【００９７】
比較例１２及び１３より、素管の製造条件である平均結晶粒径、０．５％耐力、及び伸びと、製造後の素管の第１縮径加工時における０．５％耐力の増加率が本発明の請求範囲外であると、素管が硬質であるため、管内面の加工性が悪く、所定形状の内面フィンを形成することが不可能であった。また、素管が硬質であるため、溝付プラグに欠損が生じた。尚、これらの試料は所定形状の内面溝付管が作製できなかったので、焼鈍後の混粒組織有無の確認は行わなかった。
【００９８】
比較例１４より、素管の平均結晶粒径と０．５％耐力、及び第１の縮径加工による０．５％耐力の増加率が、本発明の請求範囲を逸れると、製造後の内面溝付管は、焼鈍後に混粒組織となり、熱交換器組立のためにＵベント曲げを行うと、曲げ部にしわ及び割れ等の不具合が発生し、熱交換機の組立には使用できるものの歩留まりが大幅に低下する結果となった。
【００９９】
比較例１５は、比較例１４より軟質であり、素管の製造条件である平均結晶粒径、０．５％耐力，及び伸びと、製造後の素管の第１縮径加工時における０．５％耐力の増加率が、本発明の請求範囲外であるため、素管に作用する引抜き力により転造加工中に管に破断が生じた。尚、比較例１５については、内面溝付管の作製が不可であったため、焼鈍後の混粒組織有無の確認は行わなかった。
【０１００】
素管の製造条件である平均結晶粒径、０．５％耐力及び伸び、製造された素管の第１の縮径加工による０．５％耐力の増加率のいずれか１つでも、本発明の請求範囲から逸れた場合は、所定形状の溝が形成された内面溝付管を、プラグの欠けを発生させることなく製作することは不可能であった。
【０１０１】
（第３の実施例）
次に、第１の縮径加工における縮径加工率を変化させて、本発明の請求範囲を満足する試作管（実施例９〜１１）と、本発明の請求範囲を満足しない試作管（比較例１６〜１７）をそれぞれ作製し、所定の溝形状が形成できるかを確認した。
尚、内面溝付管の製造に用いる素管は、実施例９〜１１、及び比較例１６〜１７の全てが、平均結晶粒径が０．０１８〜０．０２３ｍｍ、０．５％耐力が８３〜９０Ｎ／ｍｍ^２、伸びが４８〜５０％である本発明の請求範囲を満足するものを用いた。また、外径の大きい素管に対しては縮径加工率が大きく取れる縮径ダイス及び縮径プラグを、一方、外径の小さい素管に対しては縮径加工率が小さく取れる縮径ダイス及び縮径プラグの組み合わせを用いて、縮径加工による０．５％耐力の増加率を変化させた。そして、作製した素管コイルに表３に示す条件を有する溝付プラグを用いて内面溝付加工を行い、長さ５００ｍの内面溝付管を作製した（引抜き速度３０ｍ／秒）。尚、内面溝付管の製造に用いた縮径ダイス及び整形ダイスは、実施例９〜１１、及び比較例１６〜１７の全ての試作管に対し、同一の物とし、整形部（整形ダイス）による第３の縮径加工は、内面溝付管の外径変化率１０％で行った。
【０１０２】
作製された内面溝付管の形状は、第２の実施例と同じものであった。この内面溝付管の定常加工部（引抜き速度が所定値に安定した部分）の先端部及び後端部より試料を採取して断面を観察して溝の成形状況を観察し、また、工具である溝付プラグの欠損有無を確認した。各試作管について、製造可否（フィンの成形性）、工具である溝付プラグの欠損有無を表５に示す。
【０１０３】
【表５】

【０１０４】
表５の結果より、本発明の実施例９、１０、及び１１のいずれもが、第１の縮径加工による０．５％耐力の増加率及び整形ダイスによる外径変化率（１０％：全試料共通）が請求範囲内であるため、所定形状の溝が形成された内面溝付管を、プラグの欠けを発生させることなく製作することが可能であった。
【０１０５】
比較例１６より、第１の縮径加工における０．５％耐力の増加率が、本発明の請求範囲の下限値より小さいと、溝付加工される管の０．５％耐力が小さく、素管に作用する引抜き力により転造加工中に破断が生じた。また、比較例１７により、第１の縮径加工における０．５％耐力の増加率が、本発明の請求範囲の上限値より大きいと、溝付加工される管の０．５％耐力が大きく、素管材が加工硬化を生じて、溝付プラグの溝に素管材料が充分に流入することができず、所定形状のフィンを形成することが不可能であった。また、素管が硬質となり、工具である溝付プラグに欠損が生じた。
【０１０６】
第１の縮径加工における０．５％耐力の増加率が、本発明の請求範囲から逸れた場合は、所定形状の溝が形成された内面溝付管を、プラグの欠けを発生させることなく製作することは不可能であった。
【０１０７】
（第４の実施例）
次に、第３の縮径加工における整形ダイスによる外径変化率が、本発明の請求範囲を満足する試作管（実施例１２〜１４）と、前記外径変化率が本発明の請求範囲を満足しない試作管（比較例１８〜１９）をそれぞれ作製し、所定の溝形状が形成できるかを確認した。尚、内面溝付管の製造に用いる素管は、実施例１２〜１４、及び比較例１８〜１９の全てが、管外径が９．５２ｍｍ、管底肉厚が０．５ｍｍ、平均結晶粒径が、０．０１８ｍｍ、０．５％耐力が８７Ｎ／ｍｍ²、伸びが４９．５％である本発明の請求範囲を満足するものを用いた。また、第１の縮径加工における素管の０．５％耐力の増加率は３．３４倍である本発明の請求範囲を満足するものを用いた。
【０１０８】
そして、作製した素管コイルに表３に示す条件を有する溝付プラグを用いて内面溝付加工を行い、長さ５００ｍの内面溝付管を作製した（引抜き速度３０ｍ／秒）。尚、第３の縮径加工における外径変化率が異なるため、作製される内面溝付管の外径、長さ、及び溝リード角は異なるものであった。
【０１０９】
前記内面溝付管の定常加工部（引抜き速度が所定値に安定した部分）の先端部及び後端部より試料を採取して断面を観察して溝の成形状況を観察し、また、外表面の転造ボールの跡を観察した結果を表６に示す。
【０１１０】
【表６】

【０１１１】
表６の結果より、本発明の実施例１２、１３、及び１４のいずれもが所定形状の溝が形成された内面溝付管を作製することが可能であり、且つ、整形ダイスにより外表面が加工を受けているため、転造ボールの跡も残存せず良好な表面状態であった。
【０１１２】
比較例１８より、第３の縮径加工における整形ダイスの外径変化率が、本発明の請求範囲の下限値より小さいと、外表面の加工率が小さいため転造ボールの跡が残存し、内面溝付管外表面の凹凸が大きい。従って、拡管によりその表面にアルミフィンを取り付けて熱交換器を作成しても、アルミフィンと管外表面との隙間が大きいことから、充分な伝熱性能を発揮させることは難しい。また、比較例１９より、前記外径変化率が、本発明の請求範囲の上限値より大きいと、引抜き荷重が増加し、加工中に管の破断が生じる。
【０１１３】
第３の縮径加工における整形ダイスによる外径変化率が、本発明の請求範囲から逸れた場合は、内面溝付管の外表面に、転造ボールまたは転造ロールの跡を残さずに、内面溝付管を作製することは不可能であった。
【０１１４】
（第５の実施例）
次に、内面溝付管の製造装置に用いる溝付プラグの炭化タングステンの平均粒度が、本発明の請求範囲を満足する溝付プラグ（実施例１５）と、前記炭化タングステンの平均粒度が、本発明の請求範囲から逸れる溝付プラグ（比較例２０）をそれぞれ用いて内面溝付管を作製し、溝付プラグの寿命を確認した。
【０１１５】
尚、内面溝付加工を行う素管は、本発明の請求範囲内である第２の実施例における実施例６の素管（管外径が９．５２ｍｍ、管底肉厚が０．５ｍｍ、平均結晶粒径が０，０１２ｍｍ、０．５％耐力が９６Ｎ／ｍｍ²、伸びが４８．５％、及び第１の縮径加工における素管の０．５％耐力の増加率が、３．０５倍）を用いた。そして、作製した素管コイルに表７に示す条件を有する溝付プラグを用いて内面溝付加工を行い、長さ２５００ｍの内面溝付管を作製した（引抜き速度２０ｍ／秒）。
【０１１６】
尚、内面溝付管の製造に用いた整形ダイスによる外径変化率は１０％とした。
そして、作製された内面溝付管は、外径７．０ｍｍ、溝リード角が約４９°、フィン高さが０．１８ｍｍ、溝数５５、フィンピッチ０．３５ｍｍ、フィン根元半径０．０９ｍｍ、及びフィン根元半径とフィンピッチの比が０．２６であった。この内面溝付管の定常加工部（引抜き速度が所定値に安定した部分）の先端部及び後端部より試料を採取して断面を観察して溝の成形状況、及び加工終了後の溝付プラグの欠損有無について観察した結果を表８に示す。
【０１１７】
【表７】

【０１１８】
【表８】

【０１１９】
表８の結果より、本発明の請求範囲内である炭化タングステンの平均粒度０．５μｍを有する実施例１５の溝付プラグを用いた場合は、内面溝付管の溝リード角が約５０°と大きい溝形状でも、最後まで欠損せず全長に渡り管内に、所定形状の溝を正しく形成することが可能であった。これに対し、本発明の請求範囲から逸れる炭化タングステンの平均粒度３μｍを有する比較例２０は、炭化タングステンの平均粒度の粗い従来の超硬製プラグを使用しているため、加工された内面溝付管後端部においては溝が正しく形成されておらず、また、加工後の溝付プラグにも欠損が発生しており、加工途中において溝付プラグの欠損が生じた。
【０１２０】
（第６の実施例）
次に、溝付プラグの自転方向と転造ボールの公転方向が、互いに同一方向である本発明の実施形態の場合と、前記溝付プラグの自転方向と転造ボールの公転方向が逆方向である本発明の実施形態ではない場合とのそれぞれの条件で、内面溝付管の溝の形成しやすさを比較した。尚、内面溝付加工を行う素管は、本発明の請求範囲内である第２の実施例における実施例７の素管（管外径が９．５２ｍｍ、管底肉厚が０．５ｍｍ、平均結晶粒径が０，０１８ｍｍ、０．５％耐力が８７Ｎ／ｍｍ²、伸びが４９．５％、及び第１の縮径加工における素管の０．５％耐力の増加率が、３．３４倍）を用いた。
【０１２１】
このようにして作製した素管コイルに表３の溝付プラグ（引抜き方向の上流側から見て右ねじ方向に溝が形成されている）を用いて、引抜き方向の上流側から見て転造ボールの公転方向を右ねじ方向（同一方向に回転）、及び引抜き方向の上流側から見て転造ボールの公転方向を左ねじ方向（逆方向に回転）とし、それぞれ内面溝付加工を行い、長さ５００ｍｍの内面溝付管を作製した。尚、転造ボールの公転の速さは同一方向回転及び逆方向回転とも同じとし、引抜き速度を変化させて、管内にフィンが正しく形成されるかを確認した。また、第３工程の整形ダイスによる外径変化率は１０％とした。
【０１２２】
正しく加工された場合は、内面溝付管内に形成されるフィンの高さは０．２ｍｍとなる。そこで、同一方向回転及び逆方向回転の条件において、管内にフィンが正しく形成される引抜き速度を測定した。その結果、その引抜き速度は、同一方向回転が逆方向回転より約１０％程度大きいことがわかった。以上より、溝リード角の大きい内面溝付管を作製する場合は、転造ボールの公転方向と溝プラグの回転方向は、同一方向とすることが、内面溝付管の生産性の面から有利であることが判る。
【０１２３】
【発明の効果】
本発明にかかる内面溝付管は、溝内の冷媒液膜が充分に攪拌されて冷媒の気液界面での温度差が小さくなるため、伝熱性能及び加工性に優れた内面溝付管を提供することができた。
【０１２４】
本発明にかかる内面溝付管の製造装置は、所定の溝形状を得られ、伝熱性能及び加工性に優れた内面溝付管を製造することができた。
【０１２５】
また、内面溝付管の製造装置に使用される溝付プラグの材質を、炭素タングステンの平均粒度が０．２μｍ以上０．９μｍ以下である超硬合金とする溝付プラグを用いることによって、溝付プラグが破損し難いため、所定の溝形状を得られ、伝熱性能及び加工性に優れた内面溝付管を製造することができた。
【０１２６】
本発明にかかる内面溝付管の製造装置は、使用される転造ボールまたは転造ロールの転造加工時における公転方向を、溝付プラグの自転方向と同一することによって、加工部分に対して転造ボールまたは転造ローラーが接する押圧時間が長く所定の溝形状を安定して得られ、伝熱性能及び加工性に優れた内面溝付管を製造することができた。
【０１２７】
本発明にかかる内面溝付管の製造方法によれば、所定特性の素管を第１の縮径加工、第２の縮径加工および転造加工ならびに、第３の縮径加工を行い、第３の縮径加工における素管の外径変化率と、第１の縮径加工における素管の０．５％耐力増加率を所定範囲にすることにより所定の溝形状が選ばれると共に、素管の断管が生じないため、伝熱性能及び加工性に優れた内面溝付管を製造する製造方法を提供することができた。また、溝付プラグの材質を特定することにより溝付プラグの破損を防止することができ、さらに、溝付プラグの自転方向と転造ボールまたは転造ロールの公転方向を同一とすることにより生産性に有利となる。
【図面の簡単な説明】
【図１】本実施形態に係る内面溝付管の断面形状を示す軸方向に破断した時の一部端面図である。
【図２】図１のＡ−Ａ線における一部拡大断面図である。
【図３】本実施形態に係る溝付プラグの溝形状を示す一部拡大断面図である。
【図４】本実施形態に係る内面溝付管の製造装置を示す断面図である。
【図５】従来の内面溝付管の製造装置を示す断面図である。
【符号の説明】
１ 製造装置
２ 縮径部
３ 転造部
４ 整形部
５、８、１４ 潤滑油供給装置
６ 縮径ダイス
７ 縮径プラグ
３９ 加工ヘッド
１０ 転造ボール
１２ 溝付プラグ
１３ プラグ軸
１５ 整形ダイス
２１、２２、２３ 潤滑油
４１ 溝底面
４２ フィン
４２ａ フィン山頂曲線部
４２ｂ フィン斜面直線部
５１ 素管
５３ 内面溝付管
θ 溝リード角
Ｈ フィン高さ
α フィン山頂角
Ｒ フィン根元半径
Ｌ フィンピッチ
Ｘ 抽伸方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internally grooved tube used as a heat transfer tube incorporated in an air-cooled heat exchanger used for home and commercial air conditioners, and in particular, has a high lead angle with excellent heat transfer performance. The present invention relates to an internally grooved tube having a groove, a manufacturing apparatus thereof, and a manufacturing method thereof.
[0002]
[Prior art]
In general, the internally grooved tube is used as a heat transfer tube incorporated in an air-cooled heat exchanger used in home and commercial air conditioners. Freon R22 and R21 have been conventionally used as the refrigerant in the heat transfer tube, but are being replaced by alternative refrigerants such as non-azeotropic refrigerant mixtures due to Freon regulations. As an inner surface grooved tube for R407C, which is a kind of alternative refrigerant, a tube with a groove lead angle formed in the inner surface grooved tube being set to 25 ° or more to improve heat transfer performance has been proposed. (For example, refer to Patent Document 1).
[0003]
Also, the fin crest angle (α) of the internally grooved tube is set to 10 to 30 °, and the ratio (H / R) of the fin height (H) to the fin root radius (R) is set to 2 to 4.5. In order to improve the heat transfer performance and production efficiency of the internally grooved tube, there has been proposed (for example, see Patent Document 2).
[0004]
Moreover, the following manufacturing apparatuses are proposed as a manufacturing apparatus of an internal grooved pipe (for example, refer patent document 3). As shown in FIG. 5, in this conventional inner surface grooved pipe manufacturing apparatus 101, the reduced diameter portion 102, the rolling portion 103, and the shaping portion 104 are provided in a line in this order. Then, by drawing the metal tube 151 along the drawing direction Y, the metal tube 151 passes through the reduced diameter portion 102, the rolling portion 103, and the shaping portion 104 in this order, and is processed into the inner grooved tube 153. It has become.
[0005]
In the reduced diameter portion 102, a reduced diameter die 106 is provided so as to contact the outer surface of the metal tube 151. The reduced diameter die 106 is an annular straight die, and the metal tube 151 passes through the opening. Further, the inner diameter of the opening of the reduced diameter die 106 continuously decreases along the drawing direction Y to form a taper on the inner surface of the reduced diameter die 106. Further, a reduced diameter plug 107 is provided at a position corresponding to the reduced diameter die 106 inside the metal tube 151 and is engaged with the reduced diameter die 106 via the metal tube 151. The reduced diameter plug 107 is a straight plug having a taper close to the taper angle of the reduced diameter die, and its outer surface is smooth. The diameter reducing die 106 and the diameter reducing plug 107 are for reducing the diameter of the metal tube 151.
[0006]
In the rolling unit 103, a processing head 139 is provided, and the processing head 139 is connected to a motor (not shown) so as to rotate around the metal tube 151. A plurality of rolling balls 110 are provided on the processing head 139 so as to be in contact with the outer surface of the metal tube 151, and the rolling balls 110 are in contact with the outer surface of the metal tube 151 by rotating the processing head 139. It is designed to rotate around the planet. Usually, the revolution direction of the rolling ball 110 and the rotation direction of the grooved plug 112 are different from each other. A grooved plug 112 is provided inside the metal tube 151. The grooved plug 112 is rotatably connected to the reduced diameter plug 107 via the plug shaft 113 and is disposed at a position corresponding to the rolled ball 110. A spiral groove is formed on the outer surface of the grooved plug 112. The rolling ball 110 and the grooved plug 112 form a groove on the inner surface of the metal tube 151.
[0007]
Further, in the shaping unit 104, a shaping die 115 is provided, and the shape of the shaping die 115 is an annular shape, and the metal tube 151 passes through the opening. The inner surface of the shaping die 115 is tapered, and the inner diameter of the opening decreases along the drawing direction Y. The shaping die 115 performs a shaping process for reducing the diameter of the metal tube 151 to a predetermined outer diameter.
[0008]
Further, on the upstream side in the drawing direction Y when viewed from the reduced diameter portion 102, a feeding device (not shown) for sequentially feeding the metal tube 151 wound around the basket is provided. On the downstream side in the direction Y, there is a drawing device (not shown) for drawing the metal tube 151 in the drawing direction Y, and a winding device (not shown) for winding the manufactured internally grooved tube 153 onto the drum and putting it in the basket. Is provided.
[0009]
Normally, in the reduced diameter portion 102, the rolled portion 103, and the shaping portion 104, a lubricating oil supply device (not shown) that supplies lubricating oil (not shown) to the outer surface of the metal tube 151 is reduced. It is provided upstream of each of the diameter die 106, the processing head 139, and the shaping die 115.
[0010]
As the material of the grooved plug 112 used in the manufacturing apparatus 101, the particle size of tungsten carbide, which is the main component, is 0.5 μm or less, and the segregation force is 3400 N / mm. ² The tensile strength is 1900 / mm ² By using the cemented carbide having the above, it is known that the strength of the grooved plug 112 is increased, the plug chipping of the grooved plug is prevented, the disconnection and product defects are reduced, and the productivity is improved. (For example, see Patent Document 3).
[0011]
Next, a conventional method of manufacturing an internally grooved tube will be described with reference to FIG. As shown in FIG. 5, the metal pipe 151 is inserted into the inner grooved pipe manufacturing apparatus 101, and rolling lubricant is injected into the metal pipe 151 to reduce the diameter-reduced plug 107 and the plug shaft 113. And a tool in which the grooved plug 112 is connected to each other. Thereafter, a drawing device (not shown) pulls the metal tube 151 in the drawing direction Y. As a result, the metal tube 151 is fed out from the delivery device (not shown) and starts moving along the drawing direction Y. Then, the metal tube 151 is processed into the internally grooved tube 153 by sequentially passing through the reduced diameter portion 102, the rolling portion 103, and the shaping portion 104.
[0012]
[Patent Document 1]
JP 9-028881 A (paragraph numbers [0005], [0021])
[Patent Document 2]
JP 2001-50679 (paragraph numbers [0010], [0019])
[Patent Document 3]
JP 2002-102916 A (paragraph numbers [0003], [0013], [0020], and FIG. 3)
[0013]
[Problems to be solved by the invention]
However, compared with the internally grooved tube with a small groove lead angle, the conventional internally grooved tube with a high lead shape with a large groove lead angle is excellent in heat transfer performance, but there are problems in processing as shown below. . When the inner grooved tube is processed by the rolling method, the rolling ball draws a spiral trajectory that forms a certain angle with the axial direction of the raw tube on the outer surface of the raw tube. The angle is determined depending on the drawing speed and the revolution speed of the rolled ball. By the way, when processing the inner surface grooved tube with the same number of grooves by making the drawing speed and the revolution speed of the rolled ball the same, one land portion of the grooved plug (the outer peripheral portion between the groove portions of the grooved plug) The trajectory of the rolled ball machining the abutting element tube becomes longer as the groove lead angle increases. This means that the larger the groove lead angle, the larger the amount of processing of the raw tube processed by the rolled ball, that is, the larger the amount of work hardening of the raw tube. For this reason, the raw tube hardly flows to the groove bottom surface of the grooved plug, and the groove of the inner surface grooved tube has a poor shape.
[0014]
At the same time, the grooved plug in contact with the inner surface of the inner surface grooved tube is directly subjected to the press load of the work-cured inner surface grooved tube. Easy to lower. Further, when the groove lead angle is increased, when the rolling process is performed at the same drawing speed, the rotation amount of the grooved plug per unit time, that is, the rotation speed is increased as compared with the case where the groove lead angle is small. This increase in rotational speed increases the mutual frictional force between the grooved plug and the tube material, which acts as a resistance to rotation of the grooved plug, and the grooved plug is likely to be chipped. Furthermore, the frictional force increases the force required to pull out the tube material, and in the case of a thin-walled tube, breakage tends to occur during processing.
[0015]
And in the conventional inner surface grooved tube, its manufacturing apparatus, and its manufacturing method, in order to improve the heat transfer performance and productivity of the inner surface grooved tube, the fin crest angle, the fin length and the fin of the inner surface grooved tube The ratio of the root radius is specified within a predetermined range, and the material of the grooved plug used in the inner surface grooved pipe manufacturing apparatus is specified. However, the above-described problem cannot be solved only by the above specification due to an increase in the groove lead angle of the internally grooved tube.
[0016]
The present invention has been devised in view of the above-described problems, and does not cause a failure of the groove shape of the inner surface grooved tube, breakage of the grooved plug as a tool, and breakage of the inner surface grooved tube due to an increase in the extraction load. An object of the present invention is to provide an internally grooved tube having a larger groove lead angle than that of the prior art and excellent in heat transfer performance and workability, a manufacturing apparatus thereof, and a manufacturing method thereof.
[0017]
[Means for Solving the Problems]
An inner grooved tube according to the present invention is an inner grooved tube made of copper or a copper alloy, in which a spiral groove is formed on the inner surface of the tube, and is formed between the groove on the inner surface and adjacent grooves. Is the groove lead angle 43 ° to 60 °, fin height (H) 0.15 mm to 0.30 mm, fin peak angle (α) 5 ° to 30 °, fin root radius (R) 0.5H or more 2 / 3H or less, fin pitch (L) 0.2mm to 0.5mm , The fin base radius to fin pitch ratio (R / L) is 0.15 or more and 0.5 or less. (Claim 1)
[0018]
According to the above-described configuration, the groove shape is configured in a predetermined shape, whereby the inner surface grooved tube sufficiently stirs the refrigerant liquid film in the groove and reduces the difference in concentration at the gas-liquid interface of the refrigerant. . Also, when manufacturing an internally grooved tube, the fin root radius (R) is set to the fin height (H). 0.5 times or more By setting it to 2/3 times or less, the pulling-out load of the raw pipe is reduced, and the reduction amount of the groove lead angle is suppressed. Furthermore, when forming the groove shape, work hardening due to plastic deformation is small, and the raw tube material is easy to flow.
[0019]
Moreover, the manufacturing apparatus of the inner surface grooved pipe according to the present invention includes a reduced diameter portion for performing a first diameter reduction process on the raw pipe with a reduced diameter plug and a reduced diameter die, and a plurality of the reduced diameter raw pipes. With the rolling balls or rolling rolls, the second diameter reduction processing and the inner surface of the base pipe are performed by pressing the grooved plug connected relatively rotatably to the diameter reduction plug via a connection shaft. A rolling part that performs a rolling process to transfer the groove shape of the grooved plug; and a shaping part that performs a third diameter reduction process by a shaping die on the raw pipe that has been reduced in diameter and rolled. , An apparatus for manufacturing an internally grooved tube that has a groove lead angle of 30 ° or more and 60 ° or less of a groove formed by adjacent fins on the tube inner surface of the element tube, wherein the grooved plug includes the groove Shape is groove depth (h) 0.15 mm to 0.30 mm, groove peak angle (β) 5 ° to 30 ° The groove base radius (r) is h / 3 mm or more and 2 h / 3 mm or less, and a cemented carbide having an average particle size of tungsten carbide of 0.2 μm or more and 0.9 μm or less is used as the material. (Claim 2)
[0020]
According to the above configuration, in the rolling part, the raw tube material sufficiently flows into the groove of the grooved plug by the pressing of the rolling ball or the rolling roll, and the desired groove shape is transferred to the inner surface of the raw tube. . In addition, since the groove shape of the grooved plug is the same as the desired groove shape formed in the raw tube, the tube material sufficiently flows into the groove of the grooved plug, so that the desired inner surface of the raw tube is formed. A groove shape is formed.
[0021]
Furthermore, according to the above-described configuration, the grooved plug is excellent in strength and has a small amount of wear. Therefore, during the rolling process, the grooved plug receives a pressing load from the raw tube material by the rolling ball or the rolling roll. However, the groove shape of the grooved plug is transferred to the inner surface of the blank without breaking. Further, since the grooved plug is harder than the raw tube material, the raw tube material easily flows into the groove of the grooved plug due to the pressing load.
[0022]
And the revolution direction at the time of the rolling process of the rolling ball or rolling roll used for the manufacturing apparatus of the internally grooved pipe according to the present invention was the same as the rotation direction of the grooved plug. (Claim 3)
[0023]
According to the above configuration, when the rolling ball or the rolling roll in the rolling part forms one groove in the raw tube, the rotation direction of the grooved plug corresponding to the revolution direction of the rolling ball or the rolling roll. Since the pressing time can be increased, the raw material of the pipe sufficiently flows into the groove of the grooved plug, and the desired groove shape is transferred to the inner surface of the raw pipe.
[0024]
The method for producing an internally grooved tube according to the present invention is a production method for producing the internally grooved tube using the production apparatus, and an extruded tube produced by hot extruding a phosphorous deoxidized copper billet, Rolled, drawn, and annealed to form a blank tube, which has an average crystal grain size of 0.01 to 0.03 mm and a 0.5% proof stress of 75 to 130 N / mm. ² The elongation is in the range of 45 to 52%, and the element tube is subjected to a first step of reducing the diameter by the reduced-diameter portion, and the shrinkage obtained in the first step. A second step in which the 0.5% proof stress of the element pipe is increased by 2.5 to 3.6 times, and the element pipe is subjected to a second diameter reduction process and a rolling process by the rolling unit; And a third step of performing a third diameter reduction processing by the shaping portion on the element tube to which the groove shape of the grooved plug is transferred in the second step, and the groove in the third step The change rate of the outer diameter of the base tube to which the groove shape of the attached plug was transferred was set to 0.5% to 18%. (Claim 4)
[0025]
According to the above configuration, due to the limited increase rate of 0.5% proof stress in the diameter reduction processing that is the first step, the raw pipe material does not flow into the groove of the grooved plug during the subsequent rolling processing. It will not be as hard. Further, the desired groove shape is transferred to the inner surface of the raw tube by the rolling process as the second step. Furthermore, by limiting the range of the outer shape change rate, which is the third step, the drawing load of the raw pipe material is reduced, the amount of decrease in the groove lead angle formed in the raw pipe is suppressed, and at the time of rolling processing The traces of the rolling balls or rolling rolls on the outer surface of the applied inner grooved tube are reduced.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a partially enlarged end view when broken in the axial direction showing the shape of an internally grooved tube, and FIG. 2 is a partially enlarged sectional view taken along line AA of FIG. FIG. 3 is a partially enlarged sectional view showing the groove shape of the grooved plug. FIG. 4 is a sectional view showing an apparatus for manufacturing an internally grooved tube.
[0027]
First, as shown in FIG. 1, the inner grooved tube of the present invention will be described. Since the internally grooved tube is required to have excellent workability and heat transfer performance, it is made of copper or a copper alloy that satisfies these conditions. A heat pipe having an outer diameter D of 8 mm or less, which is the mainstream, is used, and in order to improve heat conduction due to evaporation and condensation of the refrigerant in the pipe, the shape of the inner surface of the pipe is constituted by a spiral continuous groove. used. Therefore, as shown in FIG. 1, the inner surface groove shape of the inner surface grooved tube 53 of this embodiment is constituted by a continuous spiral groove 41 and an inclination angle of the groove 41 with respect to the tube axis (hereinafter referred to as a groove lead angle). As shown in FIG. 2, each groove 41 has a fin crest curve portion 42a and a fin slope straight portion 42b smoothly connected thereto, and each fin slope straight portion 42b. Each other is smoothly continuous with an arbitrary fin root radius R, and the fin height H, the fin peak angle α, the fin root radius R, the fin pitch L, and the ratio R / L of the fin root radius R to the fin pitch L are The scope is as described below. Further, the fin slope straight portions 42b may be smoothly continuous with a groove bottom straight portion (not shown) at an arbitrary fin root radius R.
[0028]
(Inner groove shape of inner grooved tube)
Groove lead angle θ is 30 ° to 60 °, fin height H is 0.15 mm to 0.30 mm, peak angle α is 5 ° to 30 °, fin root radius R is H / 3 mm to 2H / 3 mm The fin pitch L is 0.2 mm or more and 0.5 mm or less, and the R / L of the fin root radius R and the fin pitch ratio L is 0.15 or more and 0.5 or less. As long as each of the fin height H, the fin peak angle α, the fin root radius R, the fin pitch L, and the ratio R / L of the fin root radius to the fin pitch is a value within the predetermined range, Even when this combination is used, the inner surface groove shape having all the groove lead angles in the range of 30 ° to 60 ° is formed on the inner surface of the raw tube. As described above, in the present invention, by limiting the shape of the inner groove to the above numerical range, it is possible to provide an inner grooved tube excellent in heat transfer performance and workability in the tube.
[0029]
Hereinafter, the grounds for limiting the numerical values in the inner surface groove shape of the inner surface grooved tube according to the present invention will be described.
[0030]
(Groove lead angle θ)
As shown in FIGS. 1 and 2, the groove lead angle θ that improves the heat transfer performance in the internally grooved tube is required to be 30 ° or more. In alternative refrigerants such as non-azeotropic refrigerants, which have recently been used in an increasing amount, since two or more kinds of refrigerants (both having different boiling points) are used, refrigerant components having low boiling points evaporate first, Condensed from the high refrigerant component first. Therefore, the gas and liquid are mixed until all the refrigerant components constituting the non-azeotropic refrigerant mixture are evaporated or condensed.
[0031]
When the lead angle θ is less than 30 °, the refrigerant liquid film in the groove 41 is not sufficiently agitated, and the difference in concentration at the gas-liquid interface of the refrigerant increases, so that diffusion resistance and thermal resistance increase, thereby condensing in the tube. Since the thermal conductivity tends to decrease, the heat transfer performance deteriorates, which is not preferable. In addition, as the groove lead angle θ on the inner surface of the pipe increases, the heat transfer performance tends to improve. However, when a groove having a large groove lead angle θ is formed in the raw pipe 51, one is formed during the rolling process. When the groove is formed, since the moving distance of the material of the raw tube 51 by the rolling ball 10 or the rolling roll (not shown) becomes long, the amount of deformation of the material of the raw tube 51 in the circumferential direction increases. .
[0032]
Accordingly, the material of the raw pipe 51 undergoes work hardening due to plastic deformation due to the pressing load from the rolling ball 10 or the rolling roll (not shown), and the metal flow of the material of the raw pipe 51 is performed by the manufacturing method described later. It does not flow to the groove bottom surface of the grooved plug 12 used as a tool, and the groove has a defective shape, and the grooved plug 12 is damaged due to the press load of the material of the work-hardened blank 51. This leads to a decrease in the productivity of the tube, and furthermore, since the groove formation of the grooved plug 12 cannot be made symmetrically, the upper limit value of the groove lead angle θ is required to be 60 °.
[0033]
In the present invention, a more preferable groove lead angle is 30 ° to 45 °. The inner grooved tube of the present invention is suitable for a heat exchanger using a non-azeotropic refrigerant mixture composed of a plurality of refrigerants having different boiling points because the refrigerant stirring action is large. In order to manufacture an internally grooved tube with a groove lead angle exceeding 40 °, a grooved plug with a groove lead angle exceeding 40 ° is used. It is preferable to reduce the drawing speed of the raw tube and to increase the rotation speed of the rolling ball or the rolling roll.
[0034]
(Fin height H)
When the fin height H is less than 0.15 mm, the heat transfer performance deteriorates. When the fin height H exceeds 0.30 mm, the pressure loss increases and groove formation becomes difficult, so the heat transfer performance decreases. Therefore, by setting the fin height H to 0.15 mm or more and 0.30 mm or less, it is possible to manufacture an internally grooved tube that can form a groove and has good heat transfer performance.
[0035]
(Fin peak angle α)
When the fin peak angle α is less than 5 °, the width of the fin 42 becomes narrow, and the fin is distorted when the user of the inner grooved tube 53 is expanded (a copper tube and an aluminum fin are brought into close contact). On the other hand, when it exceeds 30 °, the cross-sectional area of the groove 41 becomes small and the heat transfer performance deteriorates. Moreover, the cross-sectional area of the fin 42 (thickness T of the raw pipe 51) increases, and the weight of the inner grooved pipe increases. Therefore, by setting the summit angle α to 5 ° or more and 30 ° or less, it is possible to manufacture an internally grooved tube capable of forming a groove and having good heat transfer performance.
[0036]
(Fin root radius R)
When the fin root radius R is less than H / 3 mm, the fin root radius R is small and the shape of the groove 41 approximates a trapezoidal shape. Therefore, in the internally grooved pipe having a large groove lead angle (θ) as in the present invention. The target shape cannot be obtained due to poor groove forming. Further, the stress received by the grooved plug used for forming the groove 41 increases, leading to the damage of the grooved plug. On the other hand, when the fin root radius R exceeds 2H / 3 mm, the fin root radius R is large, the cross-sectional area of the groove 41 is reduced, the heat transfer performance is reduced, and the cross-sectional area of the fin 42 (of the element tube 51) is reduced. Increasing the wall thickness T) increases the weight of the internally grooved tube. The inner grooved tube of the present invention has a slightly thicker structure at the fin base than the conventional one. For this reason, the pressure strength is improved as compared with the conventional one, and it is particularly suitable as a heat exchanger for R410A refrigerant that needs to be operated at a pressure about 1.6 times that of a normal refrigerant (for example, R22).
[0037]
(Fin pitch L)
When the fin pitch L is less than 0.2 mm, the heat transfer performance of the groove portion is deteriorated, and when it exceeds 0.5 mm, a phase shift is likely to occur. The phase shift means that when the fin pitch becomes longer, the flat portion of the groove plug becomes longer, so that the flexure of the material increases, and the next fin is formed while crushing the once formed fin. This is a phenomenon in which molding becomes impossible or a step or crack occurs on the fin slope. Therefore, by setting the fin pitch L to 0.2 mm or more and 0.5 mm or less, it is possible to manufacture an internally grooved tube having good heat transfer performance and no phase shift in the tube.
[0038]
(R / L of fin base radius R and fin pitch L)
When the ratio R / L is less than 0.15 or more than 0.5 from the range of the fin root radius R and the fin pitch L, it is difficult to manufacture the internally grooved tube. Therefore, by setting R / L to 0.15 or more and 0.5 or less, it is possible to manufacture an internally grooved tube that can form a groove and has good heat transfer performance.
[0039]
Next, an apparatus for producing an internally grooved tube according to the present invention will be described. As shown in FIG. 4, the manufacturing apparatus 1 includes a reduced diameter portion 2, a rolled portion 3, and a shaping portion 4. The reduced diameter portion 2 is a place where the raw pipe 51 is subjected to first diameter reduction processing of the raw pipe 51 by the reduced diameter plug 7 and the reduced diameter die 6 inserted into the raw pipe 51. Further, the rolling unit 3 rotates the reduced diameter pipe 51 relatively to the reduced diameter plug 7 via the connecting shaft 13 by a plurality of rolling balls 10 or rolling rolls (not shown). A portion for performing a rolling process for transferring the groove shape of the grooved plug 12 to the inner surface of the reduced diameter pipe and the second diameter reducing process by pressing the grooved plugs 12 connected to each other. It is. Further, the shaping portion 4 is a portion that finishes the inner diameter grooved tube 53 by performing the third diameter reduction processing with the shaping die 15 on the base tube 51 in which the diameter reduction and rolling processing and the groove is formed on the inner surface.
[0040]
Moreover, in the manufacturing apparatus 1, in the rolling part 3, the grooved plug 12 is formed from a cemented carbide material having an average particle size of 0.2 μm or more and 0.9 μm or less of tungsten carbide. Moreover, the revolution direction at the time of the rolling process of the rolling ball 10 or the rolling roll (not shown) is made to be the same as the rotation direction of the grooved plug 12.
[0041]
The inner grooved tube 53 is drawn from the state of the raw tube 51 in the manufacturing apparatus 1 in which the reduced diameter portion 2, the rolling portion 3, and the shaping portion 4 are provided in a line along the drawing direction X. In particular, the raw tube 51 passes through the reduced diameter portion 2, the rolling portion 3, and the shaping portion 4 in this order, and is processed into the inner grooved tube 53.
[0042]
In the reduced diameter portion 2, a lubricating oil supply device 5 that supplies the lubricating oil 21 to the outer surface of the raw pipe 51 is provided, and the outer surface of the raw pipe 51 is located downstream of the lubricating oil supply device 5 in the drawing direction X. A diameter-reducing die 6 is provided so as to be in contact with. The diameter-reducing die 6 is an annular straight die, through which the base tube 51 passes. Further, the inner diameter of the opening of the reduced diameter die 6 continuously decreases along the drawing direction X. That is, the inner surface of the reduced diameter die 6 is tapered. Further, a diameter-reducing plug 7 is provided at a position corresponding to the diameter-reducing die 6 inside the element tube 51 and is engaged with the diameter-reducing die 6 through the element tube 51. The reduced diameter plug 7 is a straight plug having a taper close to the taper angle of the reduced diameter die, and its outer surface is smooth. The diameter-reducing die 6 and the diameter-reduced plug 7 are for subjecting the raw tube 51 to diameter-reduction processing.
[0043]
In the rolling unit 3, a lubricating oil supply device 8 that supplies the lubricating oil 22 to the outer surface of the raw pipe 51 is provided, and on the downstream side in the drawing direction X as viewed from the lubricating oil supply device 8, a machining head 39 is provided. Is provided. The processing head 39 is connected to a motor (not shown) and rotates around the raw pipe 51 (for example, the motor rotation speed is 20000 rpm). The processing head 39 is provided with a plurality of rolling balls 10 or rolling rolls (not shown) so as to be in contact with the outer surface of the raw tube 51. When the processing head 39 rotates, the rolling balls 10 are rotated. Alternatively, the rolling roll (not shown) is configured to rotate on a planetary surface while rolling on the outer surface of the raw tube 51.
[0044]
Further, a grooved plug 12 is provided inside the base tube 51. The grooved plug 12 is rotatably connected to the reduced-diameter plug 7 via a plug shaft 13 and is disposed at a position corresponding to a rolling ball 10 or a rolling roll (not shown). A spiral groove is formed on the outer surface of the grooved plug 12. The manufacturing apparatus 1 forms a groove on the inner surface of the raw tube 51 by using a rolling ball 10 or a rolling roll (not shown) and a grooved plug 12.
[0045]
(Groove shape of grooved plug)
Next, the groove shape of the grooved plug 12 will be described. The groove shape of the grooved plug 12 is such that the groove depth (h) is 0.15 mm or more and 0.30 mm or less to obtain the inner grooved tube 53 having the groove lead angle (θ) of 30 ° or more and 60 ° or less. In the range of angle (α) 5 ° or more and 30 ° or less and groove root radius (r) h / 3 mm or more and 2h / 3 mm or less, the groove shape is adjusted to the inner grooved tube 53.
[0046]
If the shape of the grooved plug 12 is outside the predetermined range, when the inner surface grooved tube 53 is manufactured, the grooved plug 12 is damaged, and the inner surface of the raw tube 51 is poorly formed or broken. An internally grooved tube 53 having a groove lead angle of 30 ° to 60 ° with improved heat transfer performance cannot be manufactured. In addition, any combination of these values is used as long as the groove height (h), groove peak angle (β), and groove root radius (r) of the grooved plug are within the predetermined range. The inner grooved tube 53 having excellent heat transfer performance and workability in the tube having all groove lead angles (θ) in the range of 30 ° to 60 ° can be manufactured.
[0047]
In addition, the grooved element pipe 51 is reduced in the outer diameter of the pipe by a third diameter reduction process of the shaping portion 4 described later, and the element pipe 51 extends in the longitudinal direction. Further, due to the extension of the pipe accompanying the third diameter reduction, the groove lead angle (θ) and the fin pitch (L) of the inner surface of the raw pipe 51 formed by the rolling process are reduced. The degree to which the groove lead angle (θ) and the fin pitch (L) of the inner surface groove are small depends on the outer diameter change rate in the third diameter reduction processing of the shaping portion 4, and is therefore formed in the grooved plug. The groove lead angle and groove pitch are determined in consideration of this point.
[0048]
(Material of grooved plug)
When the average particle size of tungsten carbide which is the material of the grooved plug 12 is less than 0.2 μm, the tungsten carbide particle size is too small to manufacture the grooved plug. In addition, when the average particle size exceeds 0.9 μm, the tungsten carbide particle size is too large, so that the mechanical strength and toughness of the grooved plug are lowered, causing breakage and making long processing difficult. Therefore, by using a cemented carbide with an average particle size of tungsten carbide of 0.2 μm or more and 0.9 μm or less as the material of the grooved plug, it is possible to stably produce an internally grooved tube with excellent groove formability. can do. Note that the surface of the grooved plug is TiN, TiC, Si _Three N _Four When a ceramic thin film such as CVD is formed by a method such as CVD or PVD, the hardness and wear resistance of the grooved plug surface are improved, and the lifetime is further increased.
[0049]
(Revolution direction of rolling ball or rolling roll and rotation direction of grooved plug)
If the rolling process is performed in a direction in which the rolling direction of the rolling ball 10 or the rolling roll (not shown) in the rolling unit 3 is different from the direction of rotation of the grooved plug 12, When one groove is formed at a time, the pressing time of the rolling ball 10 to the base tube 51 is shortened. Therefore, by setting the revolution direction of the rolling ball 10 or the rolling roll (not shown) in the rolling portion 3 and the rotation direction of the grooved plug 12 to be the same, the inner surface of the raw tube during the rolling process. When a single groove is formed, the pressing time of the rolling ball 10 to the base tube 51 can be increased, so that a so-called forming time can be formed on the inner surface of the base tube 51. Become.
[0050]
At this time, if the groove of the grooved plug 12 is formed in the left-handed screw direction, the plug rotates clockwise as viewed in the drawing direction. Conversely, if the groove of the grooved plug 12 is formed in the right-handed screw direction, the plug rotates counterclockwise.
[0051]
Next, the shaping unit 4 will be described in detail. In the shaping unit 4, a lubricating oil supply device 14 that supplies the lubricating oil 23 to the outer surface of the raw pipe 51 is provided, and a shaping die 15 is provided downstream of the drawing direction X as viewed from the lubricating oil supply device 14. Is provided. The shape of the shaping die 15 is an annular shape, and the element tube 51 passes through the opening. The inner surface of the shaping die 15 is tapered, and the inner diameter of the opening decreases along the drawing direction X. The shaping die 15 is used to reduce the diameter of the raw tube 51.
[0052]
Furthermore, on the upstream side in the drawing direction X as viewed from the reduced diameter portion 2, there is provided a delivery portion (not shown) that sequentially feeds the raw tube 51 from the aligned and wound coils. On the downstream side of the drawing direction X, a drawing device (not shown) for drawing the base tube 51 in the drawing direction X and a winding device (not shown) for aligning and winding the manufactured inner grooved tube 53 are provided. Is provided.
[0053]
Next, the manufacturing method of the inner surface grooved pipe of the present invention will be described. The manufacturing method of the present invention is performed using the manufacturing apparatus, and includes a first step of performing first diameter reduction processing of the raw tube, and a first step of reducing the diameter of the raw tube obtained in the first step. 2 includes a second step of performing a diameter reduction process and a rolling process, and a third step of performing a third diameter reduction process of the element pipe to which the groove shape has been transferred in the second process.
[0054]
(First step)
First, the blank used in the first step is obtained by hot extruding, rolling, drawing and annealing a phosphorous deoxidized copper billet, and after the hot extrusion of the extruded tube, the average of up to 300 (C The cooling rate is 5 ° C / second or more, the average crystal grain size of the tube is 0.01 to 0.03 mm, and the 0.5% proof stress is 75 to 130 N / mm. ² The elongation is in the range of 45 to 52%.
[0055]
As the material of the base tube, phosphorus deoxidized copper such as alloy numbers C1220 and C1201 defined in JISH3300 is used. Phosphorus deoxidized copper is excellent in workability and heat conductivity, and is an indispensable metal material for heat exchangers. In forming a groove shape on the inner surface of a raw tube made of such a metal material, it is first necessary to control the characteristics of the average crystal grain size, proof stress, and elongation of the copper tube that is the raw tube. The Factors that greatly affect the average crystal grain size, proof stress, and elongation of the above-mentioned individual pipes are the cooling rate of the extruded pipe after hot extrusion and the annealing method of the raw pipe.
[0056]
(Cooling rate of extruded tube after hot extrusion)
After hot extruding the phosphorous deoxidized copper billet, recovery and recrystallization proceed with the processing energy of the extrusion until the temperature of the extruded tube reaches about 300 ° C. When the cooling rate is slow, the crystals tend to grow coarsely, and the cooling rate changes between the outer surface of the extruded tube and the inside and in the longitudinal direction, so that a mixed grain structure tends to be formed. Once a coarse crystal grain or mixed crystal is formed in an extruded tube, the mechanical properties and crystal grain size of the raw tube differ depending on the site even if annealing is performed after rolling and drawing. When a grooved process is performed on a blank, it becomes impossible to form a fin having a desired height and shape.
[0057]
For this reason, in the extruded tube after hot extrusion, the average cooling rate up to 300 ° C. is desirably 5 ° C./second or more. In order to achieve such a cooling rate, it is possible to carry out by underwater extrusion in which the water temperature is controlled in a cooling water pool, or by performing water-cooled extrusion in which shower-like cooling water is supplied over a predetermined length of the surface of the extruded tube. good. The cooling rate can be measured by measuring the temperature of the extruded tube with a radiation thermometer or a contact thermometer, and calculating the cooling rate in relation to the elapsed time after extrusion.
[0058]
In the case of phosphorus deoxidized copper billet, it is heated to about 750 to 850 ° C. and extruded by an extrusion press, but the temperature further increases by about 40 to 60 ° C. due to processing heat generation. Therefore, in practice, a facility for cooling between 800-900 ° C. and 300 ° C. at a rate of 5 ° C./second or more is required. The cooling rate is preferably 7 ° C./second or more.
[0059]
(Annealing method of raw pipe)
In order to produce a tube with the above characteristics with good production, after the hot tube extrusion, the extruded tube cooled at a predetermined cooling rate is continuously heated, rapidly heated, and rapidly cooled. It is good to carry out continuous annealing with an induction heating apparatus that can be carried out. In that case, in order to bring the average crystal grain size and mechanical properties of the raw tube into the above ranges, the heating rate is 1500 to 2000 ° C / sec, the maximum heating temperature is 650 to 800 ° C, and the temperature is 600 ° C or higher. It is desirable that the holding time be in the range of about 0.1 to 10 seconds.
[0060]
The heating temperature is appropriately determined depending on the dimensions and material of the raw tube, and other conditions and the continuous annealing apparatus are not particularly limited. However, as a continuous annealing method, the method described in JP-A-62-188727 is used. If used, it is easy to make the raw tube have the above characteristics. That is, a long copper tube is continuously heated rapidly in an induction heating furnace, cooled by a cooling device arranged downstream thereof, and then wound up under a substantially no tension after cooling. At that time, the line speed changes. If the input of the induction furnace is adjusted by setting control that changes the input in steps, etc., it is possible to prevent coarsening of the crystal grains at the start of the line, and easy control of the crystal grain size and mechanical properties Therefore, continuous annealing at high speed is possible.
[0061]
Through the above-described continuous annealing, the tube is rapidly heated to a predetermined temperature within a fraction of a second, cooled in a few seconds, has a sufficient elongation of about 50%, has a low yield strength, and has a small grain size. Tempering can be obtained. In addition, since the long element tube is continuously annealed, uniform tempering can be obtained over the entire length. In addition, after continuous annealing, the tube is wound into a basket and unrolled again for grooving. Therefore, a slight increase in proof stress and elongation occur due to plastic working of bending and unbending, but the amount of change is small. In the present invention, it is necessary to make the crystal grain size and mechanical properties of the raw tube subjected to bending and unbending after continuous annealing within the ranges described in the claims.
[0062]
As described above, in the extruded tube after hot extrusion, the average cooling rate up to 300 ° C is 5 ° C / second or more, and the average crystal grain size is 0.01 by rolling, drawing and annealing. ~ 0.03mm, 0.5% proof stress is 75 ~ 130N / mm ² A copper pipe having an elongation in the range of 45 to 52% can be provided as a raw pipe.
[0063]
Next, the grounds for limiting the numerical values of the average crystal grain size, proof stress, and elongation of the raw tube will be described.
[0064]
(Average crystal grain size of raw tube)
When the average crystal grain size of the raw tube is less than 0.01 mm, a processed structure (fibrous structure) exceeding 50% of the thickness tends to remain near the center of the thickness of the raw tube. At the time of forming a groove in the rolling process after the diameter reduction in this step, the raw tube material does not easily flow into the groove of the grooved plug, and it is difficult to obtain a predetermined groove shape. On the other hand, when the average crystal grain size of the blank tube exceeds 0.03 mm, the growth rate of the crystal grains increases, and the crystal grain of the blank tube tends to be coarsened. Such a blank tube is mixed by subsequent annealing. If it becomes a structure | tissue and a hairpin bend | folds, a rough skin and a crack will generate | occur | produce and it becomes impossible to incorporate in an heat exchanger as an internal grooved tube. Therefore, the range of the average crystal grain size of the raw tube in this embodiment is limited to 0.01 to 0.03 mm. Moreover, Preferably, it is the range of 0.015-0.025 mm.
[0065]
(0.5% proof stress of raw pipe)
By subjecting the base tube to diameter reduction processing, the base tube undergoes work hardening due to plastic deformation. Therefore, the 0.5% proof stress of the raw pipe material is increased, but the 0.5% proof stress of the raw pipe is 75 N / mm. ² If it is less than the above, in the second step, which will be described later, since the groove shape having a fin having a predetermined shape and a groove having a high lead is not sufficient in yield strength by rolling, the blank tube has a pulling force in the tube axis direction. As a result, the tube is easily broken during the rolling process.
[0066]
In addition, tension is acting on the raw pipe to be processed, but the 0.5% proof stress of the raw pipe is 75 N / mm. ² If it is less than the above, since the element tube is plastically deformed in the drawing direction by the tension, and deformation in the thickness direction of the element tube is suppressed, it is particularly difficult to produce an internally grooved tube having a large groove depth. On the other hand, the 0.5% proof stress of the raw tube is 130 N / mm ² In the case of exceeding the above, the 0.5% proof stress increased by work hardening at the time of diameter reduction processing is large, so that the raw tube at the time of rolling processing does not easily flow into the grooved plug, so that it is difficult to obtain a predetermined groove shape. Therefore, the 0.5% proof stress of the blank tube in this embodiment is 75 N / mm. ² More than 130mm ² By limiting to the following, it is possible to form a predetermined groove in the raw tube without causing breakage of the raw tube due to rolling.
[0067]
(Elongation of raw tube)
Even if the average crystal grain size and 0.5% yield strength of the blank tube are within the above ranges, if the elongation of the blank tube is less than 45%, the blank tube is subjected to a rolling process in a second step described later. At this time, since the raw tube does not sufficiently flow into the groove of the grooved plug, it is difficult to obtain fins having a predetermined height and shape. Further, if the elongation of the raw tube exceeds 52%, the elongation of the raw tube occurs during the rolling process due to the drawing force, and the breakage of the raw tube is likely to occur. Therefore, by limiting the elongation of the blank tube in this embodiment to 45% or more and 52% or less, it is possible to form a predetermined groove in the blank tube without causing breakage of the blank tube due to rolling.
[0068]
Therefore, the raw material and the characteristics of the raw tube provided in the first step are as follows: an extruded tube produced by hot extruding a phosphorous deoxidized copper billet is rolled, drawn and annealed to form a raw tube; The average cooling rate up to 300 ° C. after hot extrusion of 5 ° C./second or more, the average crystal grain size of the raw tube is 0.01 to 0.03 mm, and the 0.5% proof stress is 75 to 130 N. / Mm ² By limiting the elongation to a range of 45 to 52%, the grooved plug as a tool is not damaged, and an internally grooved tube having a high lead excellent in groove forming can be manufactured stably.
[0069]
Then, as shown in FIG. 4, the process of the present invention is performed as shown in FIG. 4, as described in the manufacturing apparatus 1. This is a process of performing diameter machining. And, by increasing the 0.5% proof stress of the raw pipe by 2.5 to 3.6 times by the first diameter reduction processing, it is possible to stably manufacture the internally grooved pipe having excellent groove formability. Can do.
[0070]
Hereinafter, the grounds for limiting the numerical value of the 0.5% proof stress increase range by the diameter reduction processing of the raw pipe 51 according to the first step of the present embodiment will be described.
[0071]
(Increase range of 0.5% proof stress of raw tube)
The raw pipe 51 having the above-described structure and mechanical properties is drawn out so as to pass between the reduced diameter die 6 and the reduced diameter plug 7, whereby the raw pipe 51 is subjected to diameter reduction processing, and the raw pipe 51 is plastic. Worked and cured by processing. With this work hardening, the 0.5% proof stress of the base tube 51 after the diameter reduction is increased as compared with that before the diameter reduction. However, in the second step described later, a rolling ball 10 or a rolling roll (not shown). ) Is rolled. At this time, the diameter reduction ratio and shape of the diameter reducing die 6 and the size and shape of the diameter reducing plug 7 capable of providing the element pipe 51 capable of forming a fin having a predetermined shape on the inner surface of the element tube 51 are selected. is required.
[0072]
The work hardening rate (0.5% yield strength increase rate) due to the diameter reduction is determined by how much the raw pipe 51 is subjected to plastic working by the diameter reducing die and the diameter reducing plug. Basically, even when the work hardening rate at this portion is 0 (the increase rate of 0.5% proof stress is 0), the predetermined groove can be formed in the inner pipe 51 by rolling. In addition, it is difficult to reduce the work hardening rate by the diameter reduction process to 0, and work hardening actually occurs. If the increase rate is less than 2.5 times, the allowance between the diameter-reducing die 6 and the diameter-reduced plug 7 is reduced, the thickness is increased, the amount of reduction is increased, the material is broken, or the diameter-reduced plug is reduced. The holding by the diameter die becomes unstable and the plug may be removed.
[0073]
Further, if the increase rate exceeds 3.6 times, the work hardening of the raw tube 51 becomes large, so that the raw tube 51 does not easily flow into the groove bottom end portion of the grooved plug 12. Accordingly, by limiting the increase rate of 0.5% proof stress of the raw tube in this embodiment to 2.5 times or more and 3.6 times or less, it is possible to form a predetermined groove in the raw tube 51.
[0074]
(Second step)
Next, in the second step, as shown in FIG. 4, the raw tube 51 reduced in diameter in the first step is subjected to the second reduced diameter by the rolling unit 3 as described in the manufacturing apparatus 1. This is a process for performing processing and rolling. Then, the base tube 51 was pressed against the grooved plug 12 with a plurality of rolling balls 10 or rolling rolls (not shown), so that the base tube 51 was subjected to a second diameter reduction process, and the diameter was reduced. In this step, the groove shape of the grooved plug 12 is transferred to the inner surface of the base tube 51.
[0075]
(Third step)
Next, as shown in FIG. 4, in the third step, the raw tube 51 having the groove shape transferred in the second step is subjected to the third reduction by the shaping unit 4 as described in the manufacturing apparatus 1. This is a place where the inner surface grooved pipe 53 is provided by performing the diameter processing. And the outside diameter change rate of the shaping die 15 in the third step is 0.5% to 18%.
[0076]
The total processing rate in the third step, that is, the processing rate after passing through all the first, second, and third steps is, for example, 20 to 40%.
[0077]
Hereinafter, the grounds for limiting the numerical value of the diameter reduction rate by the shaping die 15 of the raw tube 51 according to the third step of the present embodiment will be shown.
[0078]
The outer diameter change rate is 18 % If it exceeds, the inner grooved tube 53 is likely to break due to an increase in the pulling load. Further, when the rate of change in the outer diameter is less than 0.5%, the trace of the rolling ball 10 or the rolling roll (not shown) on the outer surface formed during the rolling process in the second step does not disappear. It is not preferable in appearance. Therefore, by changing the outer diameter change rate from 0.5% to 18%, the drawing load of the inner grooved tube 53 can be reduced and material breakage can be prevented, and the rolling ball on the outer surface of the inner grooved tube 53 can be prevented. 10 or a rolled roll (not shown) becomes small, so that the inner grooved tube 53 in which the rear of the ball or roll is inconspicuous can be stably manufactured on the outer surface.
[0079]
【Example】
Hereinafter, the present invention will be specifically described.
[0080]
(First embodiment)
The groove lead angle θ, fin height H, fin peak angle α, fin root radius R, fin pitch L, and fin root radius to fin pitch ratio R / L of the internally grooved tube all fall within the scope of the present invention. Satisfied shape (Example 1 , 2 ) And a prototype tube with Of One of them more than However, the shape does not satisfy the claims of the present invention (Comparative Examples 1 to 11) Reference examples 1 to 3 ) Were produced. For each prototype tube, the manufacturability (processability) and the heat transfer performance in the tube were evaluated, and the results are shown in Table 1.
[0081]
In Table 1, “◯” in the column “manufacturability” indicates that the manufacture was possible, and “x” indicates that the manufacture was impossible. Manufacturability was comprehensively judged from the presence or absence of breakage of the tube during the processing, the life of the grooved plug as a tool, and the like. Furthermore, the judgment in the column of the heat transfer performance measurement results is based on the measured values of the evaporation performance and the condensation performance of each inner surface grooved tube when the heat transfer performance in the inner surface grooved tube of Comparative Example 7 is 1. The case where at least one of the evaporating performance and the condensing performance is less than 1.1 is “x” (bad), and the case where both the evaporating performance and the condensing performance are 1.1 or more is “◯” (good). The case where both the evaporation performance and the condensation performance were 1.25 or more was defined as “◎” (best). In addition, “−” indicates that the heat transfer performance could not be measured because the inner grooved tube could not be manufactured. Both production feasibility and heat transfer performance were comprehensively judged, and both ○ and ◎ were evaluated as ◯, and only one of ○ and both × were determined as ×.
[0082]
Next, in the heat transfer performance measurement in the pipe by the refrigerant evaporation test and the condensation test shown in Table 2, the inner grooved pipe is a double pipe heat exchanger (hereinafter referred to as the outer pipe) having a length of 3.5 m. As an inner pipe, the refrigerant flow rate is set to 30 kg / hour in the inner grooved pipe, the refrigerant (R410A) is supplied, and water is supplied to the annular portion between the inner grooved pipe and heat exchange is performed. Thermal performance was measured. In the evaporation test, the water temperature was adjusted so that the refrigerant completely evaporated and had a predetermined degree of superheat. In the condensation test, the water temperature was adjusted so that the refrigerant was completely condensed and a predetermined degree of supercooling was obtained. Table 2 shows the conditions for the refrigerant evaporation test and the condensation test during the heat transfer performance measurement.
[0083]
[Table 1]

[0084]
[Table 2]

[0085]
From the results in Table 1, Example 1 of the present invention, 2, as well as Reference Examples 1-3 Both of these results satisfied both the manufacturability (processability) and heat transfer performance in the internally grooved tube.
[0086]
From Comparative Example 1, when the fin root radius R is less than the lower limit, it is impossible to manufacture the inner grooved tube. From Comparative Example 2, when the fin root radius R exceeds the upper limit, the heat transfer performance in the pipe is not satisfied. Therefore, when the fin root radius R deviates from the range, neither the productivity of the internally grooved tube nor the heat transfer performance in the tube is satisfied. Also, from Comparative Example 3, when the fin pitch L exceeds the upper limit value, the heat transfer performance in the pipe is not satisfied, and when the fin pitch L is less than the lower limit value of 0.2 mm from Comparative Example 4, the inner grooved tube is manufactured. Therefore, when the fin pitch L deviates from the range, neither the productivity of the internally grooved tube nor the heat transfer performance in the tube is satisfied. Furthermore, from Comparative Example 5, although it is possible to manufacture if the ratio R / L of the fin base radius R and the fin pitch L is less than the lower limit value, the heat transfer performance in the pipe is not satisfied. If the ratio R / L between the root radius R and the fin pitch L exceeds the upper limit value, it is impossible to manufacture the inner surface grooved tube. If the ratio R / L between the fin root radius R and the fin pitch L deviates from the range Neither the productivity of the internally grooved tube nor the heat transfer performance in the tube is satisfied.
[0087]
From Comparative Example 7, when the fin root radius R and the groove lead angle θ are less than the lower limit values, it is possible to manufacture the internally grooved tube, but the heat transfer performance in the tube is not satisfied. Further, from Comparative Example 8, if the fin height H is less than the lower limit value, the heat transfer performance in the pipe is not satisfied. From Comparative Example 9, if the fin height H exceeds the upper limit value, the inner grooved tube Since manufacture is impossible, when the fin height H deviates from the range, neither the productivity of the internally grooved tube nor the heat transfer performance in the tube is satisfied. Further, from Comparative Example 10, when the fin peak angle α is less than the lower limit, it is impossible to manufacture the inner grooved tube. From Comparative Example 11, when the fin peak angle α exceeds the upper limit, heat transfer in the pipe Since the performance is not satisfied, when the fin peak angle α deviates from the range, neither the productivity of the internally grooved tube nor the heat transfer performance in the tube is satisfied.
[0088]
If any one of the fin root radius R, fin pitch L, and fin root radius to fin pitch ratio R / L deviates from the scope of the present invention, the workability of the internally grooved tube or the heat transfer performance in the tube One of the results was not satisfactory.
[0089]
(Second embodiment)
Next, the average crystal grain size, 0.5% proof stress, and elongation, which are the manufacturing conditions of the raw pipe, and the rate of increase in 0.5% proof stress by the first diameter reduction of the manufactured raw pipe and the third A prototype tube (Examples 6 to 8) in which all of the outer diameter change rates due to the diameter reduction process satisfy the claims of the present invention, and a prototype tube in which three or all of the four do not satisfy the claims of the present invention. (Comparative Examples 12 to 15) were produced. The manufacturing method of the raw pipe for performing the inner surface groove processing is to cut out a plurality of billets for extrusion from a C1220 ingot (P: 0.022%) with a diameter of 300 mm, and homogenize annealing the billets at 800 to 900 ° C for about 30 minutes. Then, the extrusion element | tube was produced by hot extrusion at 800-900 degreeC, and shower water cooling (average cooling rate 10-15 degreeC / sec).
[0090]
The extruded element tube was rolled and drawn to obtain an element tube with an outer diameter of 9.52 mm and a wall thickness of 0.5 mm, and then annealed to obtain an inner grooved element tube. For the annealing, a high-frequency induction heating furnace (high-speed heating, short-time high-temperature heating, rapid cooling) or a roller hearth furnace (slow-temperature heating, 450 to 550 ° C × 30 minutes to 1 hour, slow cooling) is used. A coil of an inner grooved machining element tube having different average crystal grain size, 0.5% proof stress, and elongation was produced. The average crystal grain size was measured for the tube axis parallel section by the cutting method specified in JISH0501.
[0091]
Further, 0.5% proof stress and elongation were obtained by the methods specified in JISZ2241.
Then, the grooved plug having the conditions shown in Table 3 was subjected to inner surface grooving processing to the produced blank tube coil to produce an inner grooved tube having a length of 500 m (drawing speed 30 m / sec). The diameter-reducing dies and shaping dies used for the production of the internally grooved pipes are the same for all the prototype pipes of Examples 6 to 8 and Comparative Examples 12 to 15, and the shaping part (shaping dies). The third diameter reduction processing according to was performed at a tube outer diameter change rate of 10%.
[0092]
Also, the inner grooved tube produced has an outer diameter of 7.0 mm, a groove lead θ angle of about 42 °, a fin height H of 0.2 mm, a number of grooves of 65, a fin pitch of 0.3 mm, a fin base The radius R is 0.08 mm, and the ratio R / L of the fin root radius to the fin pitch is 0.27. Samples were taken from the front end and rear end of the steady processed part (part where the drawing speed was stabilized at a predetermined value) of this internally grooved tube, and the cross section was observed to observe the forming condition of the groove.
[0093]
Next, after annealing the remaining coil in a roller hearth furnace under the specified conditions, samples are collected from both ends of the coil and the structure of the tube axis parallel section is observed. The state of recrystallization (occurrence of mixed grains) was investigated. Table 4 shows the average crystal grain size, 0.5% proof stress and elongation, manufacturability (fin formability), the presence or absence of a grooved plug as a tool, and the presence of mixed grain structure for each prototype tube. Show.
[0094]
[Table 3]

[0095]
[Table 4]

[0096]
From the results of Table 4, any of Examples 6, 7, and 8 of the present invention can produce an internally grooved tube in which a groove having a predetermined shape is formed without causing chipping of the plug. there were. In addition, it does not become a mixed grain structure even after annealing (average grain size 20 μm), and even if U-bent bending is performed for assembling the heat exchanger, there are no defects such as wrinkles or cracks in the bent part, and the yield is high. It was possible to assemble the heat exchanger well.
[0097]
From Comparative Examples 12 and 13, the average crystal grain size, 0.5% proof stress, and elongation, which are the manufacturing conditions of the raw pipe, and the increase rate of 0.5% proof stress during the first diameter reduction processing of the raw pipe after manufacture. However, if it is outside the scope of the claims of the present invention, the raw pipe is hard, so the workability of the pipe inner surface is poor, and it is impossible to form the inner fin of a predetermined shape. Moreover, since the base tube was hard, the grooved plug was damaged. In addition, since the internal grooved tube of the predetermined shape could not be produced for these samples, the presence or absence of the mixed grain structure after annealing was not confirmed.
[0098]
From Comparative Example 14, if the average crystal grain size and 0.5% proof stress of the raw tube and the rate of increase of 0.5% proof stress by the first diameter reduction process deviate from the claims of the present invention, the inner surface after production The grooved tube becomes a mixed grain structure after annealing. When U bent is bent for heat exchanger assembly, defects such as wrinkles and cracks occur in the bent part, and the yield of what can be used for the heat exchanger assembly is increased. The result was a significant drop.
[0099]
The comparative example 15 is softer than the comparative example 14, and the average crystal grain size, 0.5% proof stress, and elongation, which are the manufacturing conditions of the raw pipe, are 0. 0 at the first diameter reduction processing of the raw pipe after manufacturing. Since the rate of increase in the 5% proof stress was outside the scope of the present invention, the pipe was broken during the rolling process due to the drawing force acting on the raw pipe. In Comparative Example 15, since it was impossible to produce an internally grooved tube, the presence or absence of the mixed grain structure after annealing was not confirmed.
[0100]
Any one of the average crystal grain size, 0.5% proof stress and elongation, which are the manufacturing conditions of the raw tube, and the increase rate of 0.5% proof stress due to the first diameter reduction of the manufactured raw tube, When deviating from the claims, it was impossible to manufacture an internally grooved tube in which a groove having a predetermined shape was formed without causing the chipping of the plug.
[0101]
(Third embodiment)
Next, by changing the diameter reduction processing rate in the first diameter reduction processing, the test tubes satisfying the claims of the present invention (Examples 9 to 11) and the test tubes not satisfying the claims of the present invention (comparison) Each of Examples 16 to 17) was prepared, and it was confirmed whether a predetermined groove shape could be formed.
In addition, as for the raw pipe | tube used for manufacture of an internal grooved pipe, all of Examples 9-11 and Comparative Examples 16-17 are average crystal grain diameters. But 0.018-0.023mm, 0.5% proof stress is 83-90N / mm ² Further, a material satisfying the claims of the present invention having an elongation of 48 to 50% was used. In addition, a diameter reducing die and a diameter reducing plug that allow a large diameter reduction rate to be obtained for a large outer diameter pipe, while a diameter reduction die that allows a diameter reduction rate to be reduced for a small outer diameter pipe. And reduced diameter plug of Using the combination, the rate of increase in 0.5% proof stress due to diameter reduction was changed. Then, the grooved plug having the conditions shown in Table 3 was subjected to inner surface grooving processing to the produced blank tube coil to produce an inner grooved tube having a length of 500 m (drawing speed 30 m / sec). The diameter-reducing dies and shaping dies used for the production of the internally grooved pipe are the same for all the prototype pipes of Examples 9 to 11 and Comparative Examples 16 to 17, and the shaping part (shaping dies). The third diameter reduction processing was performed at an outer diameter change rate of 10% of the inner grooved tube.
[0102]
The shape of the produced internally grooved tube was the same as in the second example. Samples are taken from the tip and rear end of the steady-processed part of this internally grooved tube (the part where the drawing speed is stable at a predetermined value), and the cross section is observed to observe the forming condition of the groove. The presence or absence of a grooved plug was confirmed. Table 5 shows whether each prototype tube can be manufactured (fin moldability) and whether or not the grooved plug as a tool is missing.
[0103]
[Table 5]

[0104]
From the results of Table 5, all of Examples 9, 10 and 11 of the present invention were found to have an increase rate of 0.5% yield strength by the first diameter reduction processing and an outer diameter change rate by the shaping die (10%: all Therefore, it was possible to manufacture an internally grooved tube in which a groove having a predetermined shape was formed without causing any chipping of the plug.
[0105]
From Comparative Example 16, when the rate of increase in 0.5% yield strength in the first diameter reduction processing is smaller than the lower limit value of the claims of the present invention, the 0.5% yield strength of the grooved pipe is small, Breakage occurred during the rolling process due to the pulling force acting on the tube. Further, according to Comparative Example 17, when the rate of increase in 0.5% yield strength in the first diameter reduction processing is larger than the upper limit value of the claims of the present invention, the 0.5% yield strength of the grooved pipe is large. The base tube material is work-hardened, and the raw tube material cannot sufficiently flow into the groove of the grooved plug, so that it is impossible to form fins having a predetermined shape. In addition, the base tube became hard, and the grooved plug as a tool was damaged.
[0106]
When the rate of increase in 0.5% proof stress in the first diameter reduction processing deviates from the claims of the present invention, the internally grooved tube in which the groove having the predetermined shape is formed without causing the chipping of the plug. It was impossible to produce.
[0107]
(Fourth embodiment)
Next, a test tube (Examples 12 to 14) in which the outer diameter change rate by the shaping die in the third diameter reduction processing satisfies the claimed range of the present invention, and the outer diameter change rate satisfies the claimed range of the present invention. Each of the unsatisfied prototype tubes (Comparative Examples 18 to 19) was prepared, and it was confirmed whether a predetermined groove shape could be formed. In addition, as for the raw pipe | tube used for manufacture of an inner surface grooved pipe, all of Examples 12-14 and Comparative Examples 18-19 are pipe outer diameters 9.52mm, pipe bottom thickness 0.5mm, average crystal grain. Diameter is 0.018mm, 0.5% proof stress is 87N / mm ² Further, a material satisfying the claims of the present invention having an elongation of 49.5% was used. In addition, the 0.5% proof stress increase rate of the raw pipe in the first diameter reduction processing is 3.34 times that satisfying the claims of the present invention.
[0108]
Then, the grooved plug having the conditions shown in Table 3 was subjected to inner surface grooving processing to the produced blank tube coil to produce an inner grooved tube having a length of 500 m (drawing speed 30 m / sec). In addition, since the outer diameter change rate in the third diameter reduction processing is different, the outer diameter, the length, and the groove lead angle of the inner grooved tube to be manufactured are different.
[0109]
Samples are taken from the front end and rear end of the regular grooved part of the inner grooved tube (the part where the drawing speed is stabilized at a predetermined value), the cross section is observed to observe the forming condition of the groove, and the outer surface Table 6 shows the results of observation of the traces of the rolled balls.
[0110]
[Table 6]

[0111]
From the results of Table 6, any of Examples 12, 13, and 14 of the present invention can produce an internally grooved tube in which a groove having a predetermined shape is formed, and the outer surface is formed by a shaping die. Since it was processed, the surface of the rolled ball did not remain and the surface condition was good.
[0112]
From Comparative Example 18, when the outer diameter change rate of the shaping die in the third diameter reduction processing is smaller than the lower limit value of the claims of the present invention, the trace of the rolling ball remains because the processing rate of the outer surface is small, The irregularities on the outer surface of the internally grooved tube are large. Therefore, even if an aluminum fin is attached to the surface by expanding the tube to create a heat exchanger, it is difficult to exert sufficient heat transfer performance because the gap between the aluminum fin and the outer surface of the tube is large. Further, from Comparative Example 19, when the rate of change in the outer diameter is larger than the upper limit value of the claims of the present invention, the drawing load increases and the tube breaks during processing.
[0113]
When the outer diameter change rate by the shaping die in the third diameter reduction processing deviates from the claims of the present invention, without leaving a trace of the rolling ball or rolling roll on the outer surface of the inner grooved tube, It was impossible to make an internally grooved tube.
[0114]
(Fifth embodiment)
Next, the grooved plug (Example 15) in which the average particle size of tungsten carbide of the grooved plug used in the inner surface grooved pipe manufacturing apparatus satisfies the claims of the present invention, and the average particle size of the tungsten carbide is An internally grooved tube was prepared using each of the grooved plugs (Comparative Example 20) deviating from the claims of the invention, and the life of the grooved plug was confirmed.
[0115]
In addition, the raw pipe which performs inner surface grooving is the raw pipe of Example 6 in the second embodiment within the scope of the present invention (the pipe outer diameter is 9.52 mm, the pipe bottom thickness is 0.5 mm, Average crystal grain size is 0.012 mm, 0.5% proof stress is 96 N / mm ² The elongation rate was 48.5%, and the rate of increase in 0.5% proof stress of the base pipe in the first diameter reduction processing was 3.05 times. Then, the grooved plug having the conditions shown in Table 7 was subjected to inner surface grooving processing to the produced tube coil to produce an inner grooved tube having a length of 2500 m (drawing speed 20 m / sec).
[0116]
In addition, the outer diameter change rate by the shaping die used for manufacture of the inner surface grooved tube was 10%.
The manufactured inner grooved tube has an outer diameter of 7.0 mm, a groove lead angle of about 49 °, a fin height of 0.18 mm, a groove number of 55, a fin pitch of 0.35 mm, a fin base radius of 0.09 mm, The ratio of the fin root radius to the fin pitch was 0.26. Samples are taken from the front end and rear end of the internally processed grooved tube (the part where the drawing speed is stable at a predetermined value), and the cross section is observed to form the groove, and the groove is formed after the processing is completed. Table 8 shows the results of observations regarding the presence or absence of plug defects.
[0117]
[Table 7]

[0118]
[Table 8]

[0119]
From the results of Table 8, when the grooved plug of Example 15 having an average particle size of tungsten carbide of 0.5 μm within the scope of the present invention was used, the groove lead angle of the internally grooved tube was about 50 °. Even with a large groove shape, it was possible to correctly form a groove of a predetermined shape in the pipe over the entire length without being lost to the end. In contrast, Comparative Example 20 having an average particle size of 3 μm of tungsten carbide that deviates from the claims of the present invention uses a conventional cemented carbide plug having a coarse average particle size of tungsten carbide, so that the processed inner surface grooved The groove was not formed correctly at the rear end of the tube, and the grooved plug after processing was also broken, and the grooved plug was broken during processing.
[0120]
(Sixth embodiment)
Next, in the case of the embodiment of the present invention in which the rotation direction of the grooved plug and the revolution direction of the rolling ball are the same direction, the rotation direction of the grooved plug and the revolution direction of the rolling ball are opposite directions. The ease of forming the grooves of the inner surface grooved tube was compared under the respective conditions with the case where it was not an embodiment of the present invention. In addition, the raw pipe which performs inner surface grooving is the raw pipe of Example 7 in the second embodiment within the scope of the present invention (the pipe outer diameter is 9.52 mm, the pipe bottom thickness is 0.5 mm, Average crystal grain size is 0.018mm, 0.5% proof stress is 87N / mm ² The elongation rate was 49.5%, and the rate of increase in 0.5% proof stress of the raw pipe in the first diameter reduction processing was 3.34 times.
[0121]
Using the grooved plug shown in Table 3 (grooves are formed in the right-handed screw direction when viewed from the upstream side in the drawing direction) on the blank tube coil thus produced, rolling is performed when viewed from the upstream side in the drawing direction. The ball revolving direction is the right-hand thread direction (rotating in the same direction), and the revolving direction of the rolled ball is the left-hand thread direction (rotating in the reverse direction) when viewed from the upstream side of the drawing direction. An internally grooved tube having a length of 500 mm was produced. The revolving speed of the rolled ball was the same for both the same direction rotation and the reverse direction rotation, and it was confirmed that the fins were correctly formed in the pipe by changing the drawing speed. Further, the outer diameter change rate by the shaping die in the third step was set to 10%.
[0122]
When correctly processed, the height of the fin formed in the inner grooved tube is 0.2 mm. Therefore, the drawing speed at which the fins were correctly formed in the pipe was measured under the conditions of the same direction rotation and the reverse direction rotation. As a result, the drawing speed was found to be about 10% greater in the same direction rotation than in the reverse direction rotation. From the above, when producing an internally grooved tube with a large groove lead angle, it is advantageous from the viewpoint of productivity of the internally grooved tube that the revolution direction of the rolled ball and the rotational direction of the groove plug are the same. It turns out that it is.
[0123]
【The invention's effect】
Internal grooved according to the present invention Tube Since the refrigerant liquid film in the groove is sufficiently agitated and the temperature difference at the gas-liquid interface of the refrigerant becomes small, it is possible to provide an internally grooved tube excellent in heat transfer performance and workability.
[0124]
Main departure Clearly Such internally grooved tube Manufacturing equipment Manufactures internally grooved tubes with a predetermined groove shape and excellent heat transfer performance and workability Ruko I was able to.
[0125]
Further, by using a grooved plug made of cemented carbide having an average particle size of carbon tungsten of 0.2 μm or more and 0.9 μm or less as the material of the grooved plug used in the inner surface grooved tube manufacturing apparatus, Since the attached plug is difficult to break, a predetermined groove shape was obtained, and an internally grooved tube excellent in heat transfer performance and workability could be produced.
[0126]
An apparatus for manufacturing an internally grooved tube according to the present invention is the same as the rotating direction of a rolling plug or rolling roll used in the rolling process, by making the revolving direction the same as the rotation direction of the grooved plug. It was possible to produce an internally grooved tube having a long pressing time with which a rolling ball or a rolling roller is in contact and having a predetermined groove shape stably obtained and excellent in heat transfer performance and workability.
[0127]
According to the method of manufacturing an internally grooved tube according to the present invention, the raw tube having the predetermined characteristics is subjected to the first diameter reduction processing, the second diameter reduction processing and the rolling processing, and the third diameter reduction processing, The predetermined groove shape is selected by setting the outer diameter change rate of the raw pipe in the diameter reduction processing of 3 and the 0.5% yield strength increase rate of the raw pipe in the first diameter reduction processing within a predetermined range. Therefore, it was possible to provide a production method for producing an internally grooved tube excellent in heat transfer performance and workability. In addition, it is possible to prevent the grooved plug from being damaged by specifying the material of the grooved plug, and to produce by making the rotation direction of the grooved plug the same as the revolution direction of the rolling ball or rolling roll. It is advantageous to the sex.
[Brief description of the drawings]
FIG. 1 is a partial end view of an inner grooved tube according to the present embodiment, showing a cross-sectional shape when broken in the axial direction.
FIG. 2 is a partially enlarged cross-sectional view taken along line AA in FIG.
FIG. 3 is a partially enlarged sectional view showing a groove shape of the grooved plug according to the present embodiment.
FIG. 4 is a cross-sectional view showing an apparatus for producing an internally grooved tube according to the present embodiment.
FIG. 5 is a cross-sectional view showing a conventional manufacturing apparatus for internally grooved pipes.
[Explanation of symbols]
1 Manufacturing equipment
2 Reduced diameter part
3 Rolling department
4 shaping department
5, 8, 14 Lubricating oil supply device
6 Reduced diameter dies
7 Reduced diameter plug
39 Processing head
10 Rolled balls
12 Slotted plug
13 Plug shaft
15 shaping dies
21, 22, 23 Lubricating oil
41 Bottom of groove
42 Fin
42a Fin summit curve
42b Fin slope straight section
51 Raw tube
53 Internal grooved tube
θ Groove lead angle
H Fin height
α Fin summit angle
R Fin base radius
L Fin pitch
X Drawing direction

Claims (4)

An inner surface grooved tube made of copper or a copper alloy and having a spiral groove formed on the inner surface of the tube, and the shape of the fin formed between the groove on the inner surface and the adjacent groove ,
Groove lead angle (θ) 43 ° or more and 60 ° or less,
Fin height (H) 0.15 mm or more and 0.30 mm or less,
Fin peak angle (α) 5 ° or more and 30 ° or less,
Fin root radius (R) 0.5H to 2 / 3H,
An internally grooved tube having a fin pitch (L) of 0.2 mm or more and 0.5 mm or less, and a fin base radius to fin pitch ratio (R / L) of 0.15 or more and 0.5 or less. A diameter-reduced portion that performs a first diameter-reducing process on a base pipe made of copper or a copper alloy by a diameter-reduced plug and a diameter-reduced die;
The second pipe is pressed by a plurality of rolling balls or rolling rolls against a grooved plug that is relatively rotatably connected to the reduced diameter plug via a connecting shaft. A rolling part for performing a diameter reduction process and a rolling process for transferring the groove shape of the grooved plug to the inner surface of the element tube;
The raw pipe that has been reduced in diameter and rolled has a shaping portion that performs a third diameter reduction with a shaping die,
An apparatus for producing an internally grooved tube, wherein the groove lead angle of a groove formed by adjacent fins on the tube inner surface of the raw tube is 30 ° or more and 60 ° or less,
The grooved plug has a groove shape with a groove depth (h) of 0.15 mm to 0.30 mm,
Groove peak angle (β) 5 ° or more and 30 ° or less,
Groove root radius (r) h / 3 mm or more and 2 h / 3 mm or less,
A cemented carbide alloy having an average particle size of tungsten carbide of 0.2 μm or more and 0.9 μm or less is used as the material thereof. The apparatus for manufacturing an internally grooved tube according to claim 2, wherein the rolling direction of the rolling ball or the rolling roll in the rolling part and the rotation direction of the grooved plug are the same. A manufacturing method for manufacturing the inner grooved tube according to claim 1 using the inner grooved tube manufacturing apparatus according to any one of claims 2 to 3.
An extruded tube produced by hot extruding a phosphorous deoxidized copper billet is rolled, drawn and annealed to form a blank tube. The blank tube has an average crystal grain size of 0.01 to 0.03 mm, 0.5 mm. % Proof stress is in the range of 75 to 130 N / mm ² and elongation is in the range of 45 to 52%,
A first step of subjecting the raw tube to a first diameter reduction process by the reduced diameter portion;
The reduced diameter obtained in the first step is increased by 0.5 to 3.6 times the 0.5% proof stress of the element pipe, and the element pipe is subjected to second diameter reduction processing and A second step of performing a rolling process;
Including a third step of performing a third diameter reduction processing by the shaping portion on the raw tube to which the groove shape of the grooved plug is transferred in the second step,
A method for manufacturing an internally grooved tube, wherein an outer diameter change rate of an element tube to which a groove shape of the grooved plug is transferred in the third step is 0.5% to 18%.

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