200924870 九、發明說明 【發明所屬之技術領域】 本發明是關於金屬管之彎曲加工裝置及具備彎管部之 金屬管之製造方法，特別是關於可防止金屬管減厚（管壁 '厚度減少）的同時進行彎曲加工的技術。 【先前技術】 @ 目前金屬管是被廣泛使用在設備裝置或工廠或發電廠 等產業設施中做爲石油或氣體暨各種液體等流體搬運用的 管，或者使用做爲橋樑或體育館屋頂等土木建築物的骨架 構造材。該等金屬管，是以規格化且事先形成指定形狀的 管〔直管或異形管（肘管：elbow，彎頭管：bend等）〕 廣爲使用，另一方面因應施工對象由直線形管彎曲加工後 的管（以下稱彎曲管）也因爲能夠彈性因應各種曲率暨管 路形狀需求而廣爲使用。 φ 另一方面，在製造彎曲管時，並不是單純地將素材的 直管彎曲而已，由於彎管部份的外圍側的管厚（管壁厚度 )會變薄，因此有時還是會擔心無法滿足該管相對的所需 強度暨規範。於是，直管並不是單純彎曲加工（例如參照 專利文獻1:日本特公昭54-28156號公報）而已，還提 案有朝管軸方向施加壓縮力的同時進行彎曲加工藉以防止 上述管壁厚度削減（減厚）的所謂壓縮彎曲加工相關的各 種技術（例如參照專利文獻2:日本特公平2-47287號公 報）。 -5- 200924870 【發明內容】 然而，近年來，針對石油或氣體、化學、發電等各種 設備裝置的配管，爲了達到設備裝置全體的小型化和降低 成本而有儘可能抑制管徑（外徑）加快流速進行高壓輸送 的傾向。因此，對於配管要求的趨勢是使用可承受高管內 壓力的高強度材料之同時，在彎曲加工後還是能夠使管厚 Φ 維持和素管管壁厚度相同（厚度削減接近零）。 另一方面，彎曲管的曲率半徑，基於施工容易度的考 量，不少是要求和已規格化的市售肘管等相同尺寸。然而 ，該等肘管的曲率半徑一般較小，由於曲率半徑愈小則彎 曲加工時的管外圍的管壁厚度削減量會愈增加，因此現實 上是不容易回應彎曲管減厚接近零的要求。此外，隨著彎 曲管的素材即直管的製造技術進步，已經達到以製造公差 最小値的接近値進行直管的製造，因此只要彎曲加工時有 φ 些許的厚度削減產生，恐怕就無法確保該管所需厚度。 另一方面，爲防止厚度削減採用上述壓縮彎曲時，此 時只要加大朝管軸方向施加的壓縮力就可抑制厚度削減。 但是，若該壓縮力加大則勢必導致壓縮驅動部的輸出增大 或導致壓縮驅動部支撐用的機構大型化，進而導致彎曲加 工裝置全體大型化，因此就現狀而言單純加大壓縮力是難 以充分因應上述要求。其一例，如將12B/sch8 0 (管壁厚 度 17.4mm)的鋼管以 1.5DR (彎曲半徑：478mm)的小 徑彎曲進行彎曲加工的狀況，在施加通常的壓縮力進行彎 -6- 200924870 曲加工時’鋼管的推進力約爲60 _，厚度削減率爲12.5 %，但若要讓厚度削減率爲0%，則需要約180噸（約3 倍）的推進力。 因此’本發明之目的，在於不造成金屬管壓縮彎曲加 工的壓縮驅動力增加，能夠更進一步降低管壁厚度削減。 爲解決上述課題達成目的’本發明相關的金屬管彎曲 加工裝置，具備•可將彎曲加工對象即金屬管的一部份加 φ 熱成環狀的加熱手段；可朝加該熱手段將上述金屬管往管 軸方向推進的推進手段；包括可把持著上述金屬管的同時 能夠以支軸爲中心轉動的夾臂（clamp arm)，利用該夾 臂把持著上述加熱手段所加熱的金屬管加熱部前方部份的 同時將該把持點隨著上述推進手段的金屬管推進以上述支 軸爲中心旋繞，藉此對上述金屬管施加彎曲力矩（ bending moment)的引導手段；及可將上述推進手段的金 屬管推進方向相反方向的力即拉回力以上述支軸爲支點透 〇 過上述夾臂施加在上述金屬管，藉此使壓縮力作用在該金 屬管的壓縮手段，上述壓縮手段是配置成上述拉回力的施 加點和上述支軸的距離比上述夾臂的金屬管把持點和上述 支軸的距離還大。 本發明的彎曲加工裝置，是利用上述加熱手段將金屬 管的一部份加熱成環狀的同時推進金屬管，同時，由引導 手段將通過加熱手段的金屬管引導成弧形彎曲。具體而言 ’金屬管的推進方向爲「前方」時（本申請是以朝金屬管 的推進方向前方爲「前」，反之後方爲「後」進行說明） 200924870 ，由夾臂把持著加熱部的前方部份。該夾臂是設置成能以 支軸爲中心轉動，其是隨著上述推進手段的金屬管的推進 形成轉動，隨著其轉動使上述把持部分以該支軸爲中心旋 繞對金屬管的上述加熱部施加彎曲力矩，藉此使金屬管連 續地塑性變形使金屬管能夠彎曲成圓弧形。 另一方面，藉由施加上述彎曲力矩朝管軸方向施加壓 縮力，能夠防止管外圍側減厚（管壁厚度減少）。該壓縮 力是在將管推進方向相反方向的力即拉回力以上述支軸爲 支點透過夾臂施加在金屬管的狀況下產生，但本發明是將 施加該拉回力的位置至支軸的距離形成爲比夾臂的金屬管 把持點和支軸之間的距離還大。如此一來，就能夠以較習 知爲小的拉回力使較大的壓縮力產生在金屬管，能夠減少 彎曲加工時的管壁厚度削減量。 若要達到上述「施加拉回力的位置至支軸的距離形成 爲比夾臂的金屬管把持點和支軸之間的距離還大」的條件 ，例如：只要將上述壓縮手段配置在從支軸側看比加熱手 段所加熱的金屬管加熱部（即，加工前初期狀態下夾臂的 金屬管把持點）還外側即可。 壓縮手段的具體構成，例如只要包括：固定在夾臂可 和該夾臂一起轉動的小齒輪（pinion);可和該小齒輪形 成咬合的齒條（rack );及可對伴隨著夾臂及小齒輪轉動 的上述齒條的從動加以制動，藉此產生上述壓縮力的制動 手段。 另，本發明中，壓縮手段的構成，並不限於上述的小 -8 - 200924870 齒輪和齒條所形成的機構，例如可採用鋼絲（wire)、或 齒輪（gear )、缸筒（cylinder )等其他各種驅動暨傳達 機構。對於推進手段，同樣地只要是能夠使金屬管前進的 機構並不拘其構造。 再加上，上述本發明的彎曲加工裝置，可構成爲：又 具備有可把持著金屬管後部將推進力傳達至該金屬管的後 部夾緊手段並且可朝上述加熱手段前進的移動底座（base φ )，上述推進手段，是包括一端部卡合於上述移動底座並 且另一端部卡合於上述支軸的同時可利用縮短或伸長透過 上述移動底座推進金屬管的推進驅動手段，上述壓縮手段 ，是包括一端部卡合於上述移動底座並且另一端部卡合於 上述支軸的同時利用縮短或伸長對上述金屬管施加壓縮力 的壓縮驅動手段。 上述裝置構造，是由上述後部夾緊手段把持著金屬管 後部，將設有該後部夾緊手段的移動底座利用上述推進驅 φ 動手段使該移動底座前進藉此推進金屬管。推進驅動手段 ，是一端部卡合於移動底座且另一端部卡合於上述支軸的 同時利用縮短〔例如縮短移動底座和支軸之間的距離（拉 攏移動底座或支軸）〕，或者是伸長（例如從後方推出移 動底座讓移動底座往前方行進），使移動底座和支軸相對 接近，藉此針對支軸使移動底座相對前進而推進金屬管。 此外’上述壓縮驅動手段，同樣地是一端部卡合於移 動底座且另一端部卡合於上述支軸的同時利用縮短〔例如 縮短移動底座和支軸之間的距離（拉攏移動底座或支軸） -9- 200924870 〕，或者是伸長（例如從後方推出移動底座讓移動底座往 前方行進），藉此產生上述拉回力使壓縮力產生在金屬管 〇 再加上，具有移動底座的上述裝置構造中，只要將壓 縮手段（壓縮驅動手段）如上述配置在從支軸側看比夾臂 的金屬管把持點還外側，就能夠讓夾著加工對象即金屬管 推進金屬管的推進手段和施加壓縮力的壓縮手段透過移動 U 底座形成彼此連結，配置成如翹翹板的平衡狀態，因此就 能夠讓推進金屬管的推進力其反力和防止管壁厚度削減的 壓縮力其反力互相抵消，這和該等反力的支撐全部依賴裝 置外部的裝置構造相比，該支撐構造簡便，能夠達到裝置 全體小型化。另，針對該點，將根據第1A圖至第2圖於 後述進行更詳細的說明。 此外，本發明相關的具備彎管部之金屬管之製造方法 ’是一種可將金屬管的一部份加熱成環狀的同時，可對該 φ 加熱部施加彎曲力矩和朝管軸方向的壓縮力使該金屬管的 至少一部份塑性變形成彎曲狀態的具備彎管部之金屬管之 製造方法，係把持著金屬管加熱部附近位置的同時由能以 該把持點相隔一定距離的支軸爲中心轉動的夾臂把持著該 金屬管的同時，藉由往管軸方向推進該金屬管使上述夾臂 的把持點旋繞將金屬管的至少一部份引導成弧形彎曲的另 一方面，在上述支軸起隔著比上述夾臂的金屬管把持點和 上述支軸的距離還大距離的位置，將金屬管推進方向相反 方向的拉回力以上述支軸爲支點透過上述夾臂施加在金屬 -10- 200924870 管藉此對金屬管施加壓縮力。 根據上述本發明相關的製造方法時’和上述本發明相 關的彎曲加工裝置同樣地，能夠以較習知小的力（拉回力 )讓壓縮力產生在金屬管，能夠抑制彎曲加工時的管壁厚 度減少。 本發明的製造方法中，同樣地能夠以上述方法的具體 形態，將拉回力施加在從支軸側看比加熱手段所加熱的金 D 屬管加熱部（即，加工前初期狀態下夾臂的金屬管把持點 )還外側。 另外，上述方法，可構成爲，利用可把持金屬管後部 並且朝金屬管加熱位置前進的移動底座把持著金屬管後部 的同時，利用一端部卡合於該移動底座且另一端部卡合於 上述支軸藉此執行縮短或伸長的驅動手段推進金屬管的同 時’由一端部卡合於上述移動底座且另一端部卡合於上述 支軸藉此執行縮短或伸長的驅動手段對金屬管施加壓縮力 本發明中，加工對象即金屬管的材料及尺寸（外徑、 內徑、管壁厚度尺寸）並無特別限制。例如：本發明是以 鐵爲主體的材料形成的管（例如鋼管或不銹鋼管、特殊鋼 管等）爲加工對象，但加工對象也可以是以其他金屬材料 爲主體的管或以其他金屬合金爲材料的管。又加上，本發 明中彎曲加工的部份（彎管部）可以是該管全長的一部份 也可以是該管全體。 根據本發明時，不會導致金屬管壓縮彎曲加工的壓縮 -11 - 200924870 驅動力增大，能夠更進一步降低管壁厚度削減量。 【實施方式】 [發明之最佳實施形態] 以下，根據圖面說明本發明的實施形態及實施例’首 先是說明實施形態相關的裝置原理，然後再以實施例說明 更具體化的裝置構成例。另，各圖中標有同一圖號是表示 同一部份和相當部份。 [裝置原理] 第1A圖至第1B圖爲表示本發明實施形態相關的裝 置構造槪念圖，第2圖爲表示該裝置的動作。如第1圖所 示，本實施形態的裝置，具備：可將彎曲加工對象即金屬 管1加熱成環狀的加熱線圈（coil ) 1 1及可供應電流至該 加熱線圈11的電源部12;具有夾緊部22可在加熱線圈 φ 11前方位置把持金屬管1的同時設置成能以設置在離開 該線圈11 一定距離R1之位置上的支軸A爲中心轉動的 夾臂21;具有可把持金屬管1後部的夾緊部52之同時設 置成可朝加熱線圈11前進的移動底座（以下簡稱底座） 51;可將該底座51朝支軸A推動的推進驅動部（推進驅 動手段）31;對金屬管1施加壓縮力的壓縮驅動部41; 及連結於夾臂21形成和該夾臂21 一起以支軸a爲中心 旋轉的導輪42。 支軸A是固定成不動（例如是固定在建築物結構體 -12- 200924870 或地坪），上述推進驅動部31是以卡合著該支軸A和底 座51將底座51拉向支軸A側藉此使底座51前進，如此 一來固定（把持）在底座51的金屬管1就會朝加熱線圈 11往前方被推進。此外，金屬管1的前端部是由夾緊部 22固定（把持）在夾臂21，因此隨著金屬管1的前進夾 臂21會旋轉，使金屬管1的把持點以支軸A爲中心旋繞 。如上述由夾臂21引導金屬管1，使加熱線圈11所加熱 φ 的金屬管加熱部份連續地塑性變形成彎曲，使金屬管1彎 曲成以支軸A和夾臂21把持點（夾緊部22)的距離R1 爲半徑的圓弧形狀（參照第1B圖）。 另外，此時是同時由壓縮驅動部41對金屬管1施加 壓縮力。具體而言，壓縮驅動部41是一端卡合於底座51 ，另一端卡合於導輪42的外圍（B點），驅動成拉攏兩 者51、B縮短該等之間的距離。導輪42是隨著上述金屬 管1推進造成的夾臂21旋轉形成旋轉，捲繞著壓縮驅動 φ 部41和導輪42之連結構件45 (例如鍊條（chain)或鋼 絲（wire )、齒條（rack )、桿（rod )等/具體構成將於 後述），或者被推進往前方（金屬管1推進方向），但壓 縮驅動部41是產生反抗該捲繞或推進的力量（拉回力或 制動力）。該拉回力會透過導輪42及夾臂21對金屬管1 作用朝管軸方向的壓縮力，抑制管外圍部份的管壁厚度削 減。 此外’上述裝置構造中，拉回力產生用的壓縮驅動部 41是配置在從支軸A側看比金屬管1還外側，並且，成 -13- 200924870 爲支點的支軸A至拉回力施加點（力點）B的距離R2, 是比支軸A至壓縮力作用點即夾臂21的金屬管1把持點 (夾緊部22 )的距離R1還大。因此，利用以支軸A爲支 點的槓桿原理，即使以較小的拉回力還是能夠對金屬管1 施加較大的壓縮力。再加上，本裝置構造的特徵如下述說 明。 [裝置動作] 當對推進驅動部31及壓縮驅動部41進行驅動開始彎 曲加工時，如上述，底座51會朝支軸A側前進，其前進 速度爲V1。此外，該底座51的前進會讓加熱線圈11所 加熱的點（加熱點）P也前進，夾臂21的旋轉會讓該加 熱點P以支軸A爲中心旋繞（參照第1B圖）。另，加熱 線圈1 1是不移動，該加熱線圈1 1所加熱的管部份（加熱 點）是在彎曲變形後例如用水或壓縮空氣等冷卻劑加以急 冷卻依順序連續進行塑性加工。第2圖，是表示從加工開 始經過時間11時的裝置各點（支軸A、加熱點P、拉回力 施加點B及底座X〇 )沿著管軸方向形成位移的圖。如該 圖所示，底座51是從初期位置X〇朝支軸A僅移動VlXtl 〇 此外，當隨著該底座51的前進形成前進的加熱點P 的速度爲V時，該前進速度¥在金屬管1的壓縮率爲β時 是如下式所示，該前進速度V爲加工速度。 v = Vj · β ) …（1)式 -14- 200924870 另外，此時’於同時卡合於導輪42的壓縮驅動部41 的卡合點（拉回力施加點）B也會前進，該前進速度V2 是由壓縮驅動部控制成如下式所示。 V2=Vi· R2/R1 …（2)式 從上述（U式及（2)式可導出下述（3)式，夾臂 21旋繞相關的上述各點A、P及B的位移會形成均衡。另 ’第1B圖及第2圖中，各點p及b位移後（t= t!) 的點分別以X!、B!表示。支軸A是被固定著因此沒 有位移。此外，B- Bi及p- Ρι實際上是成爲圓弧形，但 第2圖中是以直線表示。 V2 /v = R2/R1 …（3)式 上述動作中，利用推進驅動部31對A點（支軸）產 〇 生反力形成的張力F1使得底座51以速度Vi前進驅動（ 參照第1A圖）’隨著該底座51的前進，在金屬管1的 後部會施加有和張力F 1相同的推力F 1，利用壓縮驅動部 41對底座51產生反力形成的張力F2使拉回力（制動力 )F2施加在導輪42的外圍（夾臂21的前端部）。上述 推力F1，除了和拉回力F2有靜態平衡關係以外，還和包 括金屬管1的彎曲變形抵抗力fb或金屬管1的壓縮變形 抵抗力fp’再加上隨著該加工裝置構成用的各部要素移 動產生的動摩擦力f/z爲其負荷的金屬管速度乂！的前進動 -15- 200924870 作有動態平衡關係。此外，該等負荷當中壓縮變形抵抗力 fp是和壓縮力Fp成動態平衡。 於此’上述彎曲變形抵抗力fb或壓縮變形抵抗力fp ，是加工目的上必須的力量。此外，也是不容易成爲擾亂 加工動作主要原因的力量。其理由是，同軸作用在金屬管 1，並且，變形抵抗力是由溫度決定成大致一義的穩定値 。相對於此，隨著裝置要素移動產生的上述動摩擦力fy φ ，是異軸作用在金屬管1，除此之外在如彎曲加工般的低 速動作下乾燥摩擦以至於邊界摩擦會成爲支配性伴隨不規. 則振幅的時常變動因此容易擾亂加工動作。不過，本裝置 構造，其優點是可使上述的異軸力量夾著金屬管1以翹翹 板般的形態作用因此異軸力量大部份都被抵銷（即使沒有 完全抵銷但可降低相當大量的異軸力），能夠緩和對加工 動作的外來擾亂。 又加上，本裝置構造，如上述，夾著金屬管1以翹翹 ❹ 板般的形態配置推進驅動部31和壓縮驅動部41，由底座 51和夾臂21夾著金屬管1作用推進力和壓縮力，形成所 謂的“閉式構造”，因此除了事先要固定支軸A以外並 不需要其他的固定點（基礎），能夠使裝置全體小型化也 是其優點之一。以下，針對本發明更具體的裝置構成例進 行說明。 [實施例1] 第3A圖至第3B圖，是圖示著本發明第一實施例相 -16- 200924870 關的彎曲加工裝置。如該等圖所示，該彎曲加工裝置，具 備：可對彎曲加工對象即金屬管1進行加熱的加熱線圈 11;可對該加熱線圈11供應高頻電流的電源部12;可把 持著金屬管1前端部進行旋轉的夾臂21;可把持著金屬 管1後部朝加熱線圈11前進的底座51;可使底座51前 進的推進驅動部31;對金屬管1施加壓縮力的壓縮驅動 部41;及固定在支軸A的同時支撐底座51使底座51可 0 朝支軸A前進的台座10。 夾臂21具備有可把持著加熱線圈11所加熱的金屬管 1加熱部正近前方位置的前部夾緊部22，設置成能以支軸 A爲中心轉動。加熱線圈11，於該例中是透過來自於電 源部12的高頻電流供應對金屬管1進行感應加熱，但並 不限於感應加熱線圈，例如也可使用如燃氣器（gas burner )般的其他加熱手段。 底座51具備有可把持著金屬管1後部的後部夾緊部 Q 52，設置在支軸A所固定的台座10，形成能夠朝加熱線 圈11及支軸A成直線形（筆直）前進。該底座51(因此 是指該底座51所把持的金屬管1)，是由推進驅動部31 朝加熱線圈11及支軸A推進。推進驅動部31是可由固 定在台座10的缸筒（例如油壓缸筒）32構成，將該缸筒 33所具備的活塞桿（piston rod) 33連接在底座51後端 部藉此對底座51施加推進力。 另，於該例是利用2支缸筒32推進底座51，但也可 具備有1支或3支以上的該缸筒。此外，上述前部夾緊部 -17- 200924870 22及後部夾緊部52,例如是可採用筒夾式夾筒（collet chuck)，但只要是能夠把持金屬管1的機構’並不拘採 用任何的夾筒（chuck )或夾緊具（clamp )機構。 另一方面，壓縮驅動部41是可由固定在底座51的缸 筒（例如油壓缸筒）43構成，在該缸筒43所具備的活塞 桿44前端設置齒條45，將與該齒條45咬合的齒設置在 導輪42的外圍。導輪42是由如上述可和齒條45咬合的 Q 齒在其外圍具備的小齒輪構成，固定在夾臂21形成可和 夾臂21 —起以支軸A爲中心旋轉。因此，當金屬管1受 到推進時，夾臂21會旋轉，使導輪42和夾臂21—起旋 轉造成齒條45往前方（朝和金屬管1同一方向）前進（ 參照第3B圖），但壓縮驅動部41構成用的上述缸筒43 是會讓該齒條45作用著朝該齒條45前進反方向的拉回力 。如此一來，就能夠透過小齒輪（導輪）42、夾臂21及 前部夾緊部22對金屬管1朝管軸方向施加壓縮力。 〇 本實施例是根據本發明，以夾著金屬管ι(加工前的 金屬管部份）在支軸A相反側配置上述壓縮驅動部41， 使支軸A至壓縮驅動部41 (拉回力的施加點即齒條45和 小齒輪42的咬合部）的距離R2比支軸A至金屬管1把 持部（前部夾緊部22)的距離（或者是，支軸A和加熱 線圈1 1所加熱的加熱部的距離）R1還大，因此能夠以較 小的拉回力對金屬管1有效地施加壓縮力能夠抑制彎曲加 工時的管壁厚度削減。 -18- 200924870 [實施例2] 第4圖是圖示著本發明第二實施例相關的彎曲加工裝 置。如該圖所示’該彎曲加工裝置是和上述第一實施例相 同，具備有金屬管1加熱用加熱線圏11、電源部12、夾 臂21、底座51、推進驅動部31 (推進用缸筒32及活塞 桿33)、壓縮驅動部41 (壓縮用缸筒43、活塞桿44及 齒條45)、導輪（小齒輪）42、支軸A及台座10，但和 0 上述第一實施例不同之處是將推進驅動部31的缸筒32固 定在底座51的同時，將推進驅動部31的活塞桿33前端 部固定在支軸A，利用活塞桿33被拉入推進用缸筒32內 使底座51朝支軸A拉攏前進。 此外，針對金屬管1的推進方向在夾著金屬管1的一 方側配置支軸A和推進驅動部3 1，另一方側配置壓縮驅 動部41，可和上述第一實例相同使支軸A至壓縮驅動部 41 (拉回力的施加點即齒條45和小齒輪42的咬合部）的 〇 距離R2比支軸A至金屬管1把持部（前部夾緊部22)的 距離R1還大，另，其他的構成因是和上述第一實施例相 同，所以圖中是標示相同圖號省略重覆說明（第三實施例 也是相同狀況）。 [實施例3] 第5圖是圖示著本發明第三實施例相關的彎曲加工裝 置。如該圖所示，該彎曲加工裝置是和上述第一實施例相 同，具備有加熱線圈11、電源部12、夾臂21、底座51、 -19- 200924870 推進驅動部31(推進用缸筒32及活塞桿33)、壓縮驅動 部41(壓縮用缸筒43、活塞桿44及齒條45)、導輪（ 小齒輪）42、支軸A及台座10，但和上述第—實施例不 同之處是當以加熱線圈11所加熱的金屬管1加熱部[或 者是初期裝置（加工開始時）的夾臂21的金屬管1把持 點〕爲基準時，在支軸A同側配置壓縮驅動部41。 該壓縮驅動部41是和上述第一實施例相同，具有壓 縮用缸筒43和前端具備齒條45的活塞桿44，但壓縮用 缸筒43並不是固定在台座10或支軸A。而是透過固定錨 固螺栓（anchor) 46固定在例如地坪。齒條45是和與夾 臂2 1 —起以支軸A爲中心旋轉的小齒輪（導輪）4 2形成 咬合，隨著金屬管1 (底座51)的推進朝後方後退，但壓 縮用缸筒43是可產生朝著與此相反方向（前方）的力量 (拉回力/制動力），藉此透過齒條45、小齒輪42及夾臂 21對金屬管1施加管軸方向的壓縮力。 另，該實施例中，同樣地，支軸A至壓縮驅動部41 (拉回力的施加點即齒條45和小齒輪42的咬合部）的距 離R2是形成比支軸A至金屬管1把持部（前部夾緊部22 )的距離（或者是，支軸A和加熱線圈1 1所加熱的加熱 部的距離）R1還大。 以上，是針對本發明的實施形態及實施例進行了說明 ，但本發明並不限於此，該當業者應該明白在申請專利範 圍所記載的範圍內是可進行各種變更。 例如：上述實施例中，對金屬管施加壓縮力用的機構 -20- 200924870 (壓縮驅動部、導輪）是使用齒條和小齒輪，但也可使用 鏈條和鏈輪（sprocket )，或者，使用鋼絲和捲繞鼓輪（ drum)，或者是使用其他的動力傳達機構。此外，金屬管 把持用的夾緊手段，只要是能夠承受施加在金屬管的彎曲 力矩，相對於管軸方向的軸方向力（管長度方向的推力） 不產生滑移（slip )的機構，也可以是上述以外的各種機 構。再加上，對於其他的推進驅動部或夾臂、移動底座也 Q 是同樣狀況可採用圖面所示例以外的各種機構暨構造。 【圖式簡單說明】 第1A圖爲表示本發明實施形態相關的裝置構造（加 工開始前的初期狀態）槪念圖。 第1B圖爲表示發明實施形態相關的裝置構造（加工 中的狀態）槪念圖。 第2圖爲上述裝置構造的動作（從加工開始經過時間 〇 U時的狀態）說明槪念圖。 第3A圖爲表示本發明第一實施例相關的彎曲加工裝 置（加工開始前的初期狀態）圖。 第3B圖爲表示本發明第一實施例相關的彎曲加工裝 置（加工中的狀態）圖。 第4圖爲表示本發明第二實施例相關的彎曲加工裝置 圖。 第5圖爲表示本發明第三實施例相關的彎曲加工裝置 圖。 -21 - 200924870 【主要元件符號說明】 A :支軸 1 :金屬管（彎曲加工對象物 I 0 :台座 II :加熱線圈 1 2 :電源部 © 21 :夾臂 22 :前部夾緊部 31 :推進驅動部 3 2 :推進用缸筒 33、44 :活塞桿 41 :壓縮驅動部 42:導輪（小齒輪） 4 3 :壓縮用缸筒 ❹ 45 :齒條 46:固定錯固螺检 51 :移動底座 52 :後部夾緊部 -22BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending apparatus for a metal pipe and a method of manufacturing a metal pipe having the bent pipe portion, and more particularly to preventing a metal pipe from being thickened (thickness reduction of the pipe wall) The technology of bending at the same time. [Prior Art] @ Currently, metal pipes are widely used in industrial facilities such as equipment installations or factories or power plants as pipes for fluid transportation such as petroleum or gas and various liquids, or as civil constructions such as bridges or stadium roofs. The skeleton structure of the object. These metal pipes are widely used in the form of straight pipes or straight pipes (elbow pipes, elbow pipes, bends, etc.) which are standardized and have a predetermined shape in advance. On the other hand, the construction object is a straight pipe. The tube after bending (hereinafter referred to as a bending tube) is also widely used because of its flexibility in responding to various curvatures and pipe shape requirements. φ On the other hand, when manufacturing a curved tube, the straight tube of the material is not simply bent, and the tube thickness (wall thickness) on the outer peripheral side of the curved portion is thinned, so sometimes there is a fear that it may not be possible. Meet the relative strength and specifications of the tube. Therefore, the straight pipe is not a simple bending process (see, for example, Japanese Patent Publication No. Sho 54-28156), and it is proposed to perform a bending process while applying a compressive force in the tube axis direction to prevent the thickness of the pipe wall from being reduced ( Various techniques related to compression bending processing (see, for example, Patent Document 2: Japanese Patent Publication No. 2-47287). -5-200924870 [Invention] In recent years, piping for various equipments such as petroleum, gas, chemical, and power generation has been suppressed as much as possible in order to reduce the size and cost of the entire equipment. The tendency to speed up the flow rate for high pressure delivery. Therefore, the trend for piping requirements is to use a high-strength material that can withstand the pressure inside the high pipe, and to maintain the tube thickness Φ and the thickness of the tube wall after the bending process (thickness reduction is close to zero). On the other hand, the radius of curvature of the curved tube is required to be the same size as the commercially available elbow tube which has been standardized, based on the ease of construction. However, the radius of curvature of the elbows is generally small, and the smaller the radius of curvature, the more the wall thickness reduction at the periphery of the tube during bending is increased, so that it is not easy to respond to the requirement that the bending tube is reduced to near zero. . In addition, with the advancement in the manufacturing technology of the material of the curved pipe, that is, the straight pipe, the production of the straight pipe with the minimum manufacturing tolerance is achieved. Therefore, as long as a slight thickness reduction occurs during the bending process, it is impossible to ensure the The required thickness of the tube. On the other hand, in order to prevent the thickness from being reduced by the above-described compression bending, it is possible to suppress the thickness reduction by increasing the compression force applied in the tube axis direction. However, if the compression force is increased, the output of the compression drive unit is increased or the mechanism for supporting the compression drive unit is increased in size, and the entire bending apparatus is increased in size. Therefore, simply increasing the compression force is the current situation. It is difficult to fully meet the above requirements. For example, a steel pipe of 12B/sch8 0 (thickness: 17.4 mm) is bent at a small diameter of 1.5 DR (bending radius: 478 mm), and a normal compression force is applied to bend -6-200924870. At the time of processing, the propelling force of the steel pipe is about 60 _, and the thickness reduction rate is 12.5%. However, if the thickness reduction rate is 0%, about 180 tons (about 3 times) of the propulsive force is required. Therefore, the object of the present invention is to increase the compression driving force without causing the compression and bending of the metal pipe, and to further reduce the wall thickness reduction. In order to achieve the object of the above-mentioned problems, the metal pipe bending apparatus according to the present invention includes a heating means capable of adding a part of a metal pipe to which a bending process is to be heated to a ring shape, and the metal may be added by the heat. A propulsion means for advancing the tube in the direction of the tube axis; and a clamp arm capable of holding the metal tube while rotating around the support shaft, and holding the metal tube heating portion heated by the heating means by the clamp arm a guiding means for applying a bending moment to the metal pipe, and a guiding means for applying a bending moment to the metal pipe, along with the metal pipe of the propulsion means; a force in a direction opposite to the direction in which the metal pipe is advanced, that is, a pulling force is applied to the metal pipe through the above-mentioned clamp arm as a fulcrum, whereby a compression force acts on the compression means of the metal pipe, and the compression means is configured The distance between the application point of the pulling back force and the support shaft is larger than the distance between the metal tube holding point of the clamp arm and the support shaft. In the bending apparatus of the present invention, the metal pipe is pushed while heating a part of the metal pipe by the heating means, and the metal pipe by the heating means is guided by the guiding means to be curved. Specifically, when the direction of advancement of the metal pipe is "forward" (this application is "front" toward the front in the direction of advancement of the metal pipe, and the rear is "post"), 200924870, the heating portion is held by the clamp arm. The front part. The clamping arm is arranged to be rotatable about a fulcrum, which is formed by the advancement of the metal tube of the advancing means, and the heating of the metal tube is performed by the holding portion around the fulcrum as the rotation thereof rotates The bending moment is applied to the metal tube, thereby continuously plastically deforming the metal tube to bend the metal tube into a circular arc shape. On the other hand, by applying the above-mentioned bending moment to apply a compressive force in the tube axis direction, it is possible to prevent the peripheral side of the tube from being thickened (the thickness of the tube wall is reduced). The compressive force is generated in a state in which the force in the opposite direction of the pipe advancing direction, that is, the pulling back force is applied to the metal pipe through the clamp arm with the fulcrum as a fulcrum, but the present invention is to apply the pulling force to the fulcrum. The distance is formed to be larger than the distance between the holding point of the metal tube of the clamp arm and the support shaft. As a result, a large compression force can be generated in the metal tube with a relatively small pulling force, which can reduce the amount of wall thickness reduction during bending. In order to achieve the above-mentioned condition that the distance from the position where the pulling force is applied to the fulcrum is formed to be larger than the distance between the holding point of the metal pipe of the clamp arm and the fulcrum, for example, the above compression means is disposed in the branch The axial side may be outside the metal tube heating portion heated by the heating means (that is, the metal tube holding point of the clamp arm in the initial state before processing). The specific configuration of the compression means includes, for example, a pinion that is fixed to the clamp arm and rotatable together with the clamp arm; a rack that can be engaged with the pinion; and the accompanying clamp arm and The above-described rack of the pinion gear is driven to brake, thereby generating a braking means for the above-described compressive force. Further, in the present invention, the configuration of the compression means is not limited to the above-described mechanism of the gear and the rack of the small -8 - 200924870, and for example, a wire, a gear, a cylinder, or the like may be used. Various other drive and communication agencies. In the same manner, the mechanism for advancing the metal pipe is not limited to the structure. Further, the bending apparatus of the present invention may be configured to include a moving base (base) capable of holding a rear clamping means for transmitting a propulsive force to the metal pipe at a rear portion of the metal pipe and advancing toward the heating means. Φ), the propulsion means is a propulsion driving means for engaging a metal pipe by shortening or elongating through the moving base while the one end portion is engaged with the moving base and the other end portion is engaged with the support shaft, and the compression means is The present invention comprises a compression driving means for applying a compressive force to the metal tube by shortening or elongating while the one end portion is engaged with the moving base and the other end portion is engaged with the support shaft. In the above device structure, the rear portion of the metal pipe is held by the rear clamping means, and the moving base provided with the rear clamping means advances the moving base by the advancement driving means to advance the metal pipe. The propulsion driving means is that the one end is engaged with the moving base and the other end is engaged with the fulcrum, and the shortening is performed (for example, shortening the distance between the moving base and the fulcrum (pulling the moving base or the fulcrum)), or Elongation (for example, pushing the moving base from the rear to move the base forward) makes the moving base and the fulcrum relatively close, thereby advancing the metal tube by advancing the moving base relative to the fulcrum. In addition, the above-described compression driving means similarly uses one end to be engaged with the moving base and the other end is engaged with the fulcrum, and is shortened (for example, shortening the distance between the moving base and the fulcrum (pulling the moving base or the fulcrum) ) -9- 200924870 〕, or elongation (for example, pushing the moving base from the rear to move the base forward), thereby generating the above-mentioned pull-back force to generate a compressive force in the metal tube, plus the above-mentioned moving base In the device structure, as long as the compression means (compression driving means) is disposed outside the holding point of the metal pipe of the clamp arm as viewed from the side of the support shaft, the pushing means for advancing the metal pipe with the metal pipe to be processed can be The compression means for applying the compressive force is connected to each other by the moving U base, and is arranged in an equilibrium state such as a seesaw, so that the reaction force of the propelling force of the propelling metal pipe and the compressive force for preventing the thickness reduction of the pipe wall are mutually reacted. Offset, this and the support of the reaction forces all depend on the device structure outside the device, the support structure is simple, and the device can be fully realized. miniaturization. In addition, this point will be described in more detail later on the basis of Fig. 1A to Fig. 2 . Further, the method for manufacturing a metal pipe having a bent portion according to the present invention is a method in which a part of the metal pipe is heated into a ring shape, and a bending moment and a compression in the tube axis direction can be applied to the φ heating portion. A manufacturing method of a metal pipe having a bent pipe portion in which at least a part of the metal pipe is plastically deformed into a curved state, and is held by a fulcrum that can be separated by a certain distance from the holding point while holding a position near the heating portion of the metal pipe While the center-rotating clamp arm holds the metal tube, the other side of the metal tube is guided to be curved by bending the holding point of the clamp arm by advancing the metal tube toward the tube axis. a pulling force that is opposite to a distance between the metal pipe holding point and the support shaft is greater than a distance between the metal pipe holding point of the clamp arm and the support shaft, and the pulling force of the opposite direction of the metal pipe is transmitted through the clamp arm with the support shaft as a fulcrum The metal-10-200924870 tube thereby applies a compressive force to the metal tube. According to the manufacturing method according to the present invention described above, in the same manner as the bending apparatus according to the above-described present invention, the compression force can be generated in the metal tube with a relatively small force (pullback force), and the tube during bending can be suppressed. The wall thickness is reduced. In the manufacturing method of the present invention, similarly, in the specific form of the above method, the pulling back force can be applied to the gold D-tube heating portion heated by the heating means as viewed from the side of the support shaft (that is, the clamping arm in the initial state before processing) The metal tube handles the point) also outside. Further, in the above method, the rear portion of the metal pipe may be held by the movable base that can grip the rear portion of the metal pipe and advance toward the heating position of the metal pipe, and the one end portion is engaged with the movable base and the other end portion is engaged with the above The fulcrum thereby performs the shortening or elongation driving means to advance the metal tube while applying a compression to the metal tube by the one end portion being engaged with the moving base and the other end portion being engaged with the fulcrum to thereby perform the shortening or elongation of the driving means. In the present invention, the material and size (outer diameter, inner diameter, and wall thickness) of the metal pipe to be processed are not particularly limited. For example, in the present invention, a tube formed of a material mainly composed of iron (for example, a steel pipe or a stainless steel pipe, a special steel pipe, or the like) is processed, but the object to be processed may be a pipe mainly composed of other metal materials or made of other metal alloys. Tube. Further, the bent portion (elbow portion) in the present invention may be a part of the entire length of the tube or may be the entire tube. According to the present invention, the compression of the metal pipe is not compressed and the bending force is increased. -11 - 200924870 The driving force is increased, and the wall thickness reduction amount can be further reduced. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments and examples of the present invention will be described with reference to the drawings. First, the principle of the device according to the embodiment will be described first, and then a more specific device configuration example will be described by way of examples. . In addition, the same drawing numbers in the respective drawings indicate the same parts and the equivalent parts. [Device principle] Figs. 1A to 1B are views showing the structure of the device according to the embodiment of the present invention, and Fig. 2 is a view showing the operation of the device. As shown in Fig. 1, the apparatus of the present embodiment includes a heating coil 1 1 capable of heating a metal pipe 1 which is a bending target, and a power supply unit 12 capable of supplying a current to the heating coil 11; The clamping portion 22 is configured to hold the metal tube 1 at a position in front of the heating coil φ 11 while being disposed so as to be rotatable about a support shaft A disposed at a position away from the coil 11 by a distance R1; The clamping portion 52 at the rear of the metal tube 1 is simultaneously provided as a movable base (hereinafter referred to as a base) 51 that can advance toward the heating coil 11; a propulsion driving portion (propulsion driving means) 31 that can push the base 51 toward the support axis A; A compression driving portion 41 that applies a compressive force to the metal pipe 1; and a guide pulley 42 that is coupled to the clamp arm 21 and that rotates about the support shaft a together with the clamp arm 21. The support shaft A is fixed to be stationary (for example, fixed to the building structure -12-200924870 or the floor), and the propulsion driving portion 31 is configured to pull the base 51 toward the fulcrum A by engaging the fulcrum A and the base 51. The side thus advances the base 51, so that the metal pipe 1 fixed (held) on the base 51 is pushed forward toward the heating coil 11. Further, the front end portion of the metal pipe 1 is fixed (held) by the clamp portion 22 to the clamp arm 21, so that as the forward clamp arm 21 of the metal pipe 1 rotates, the holding point of the metal pipe 1 is centered on the support axis A. Circling. The metal pipe 1 is guided by the clamp arm 21 as described above, so that the heating portion of the metal pipe heated by the heating coil 11 is continuously plastically deformed to bend, and the metal pipe 1 is bent to be held by the support shaft A and the clamp arm 21 (clamping) The distance R1 of the portion 22) is an arc shape of a radius (see Fig. 1B). Further, at this time, the compression force is applied to the metal pipe 1 by the compression drive unit 41 at the same time. Specifically, the compression drive unit 41 has one end engaged with the base 51 and the other end of which is engaged with the outer periphery (point B) of the guide pulley 42, and is driven to draw the distance between the two 51 and B to shorten the distance therebetween. The guide pulley 42 is rotated by the rotation of the clamp arm 21 caused by the advancement of the metal pipe 1, and the connection member 45 (for example, a chain or a wire, a rack) that compresses the drive φ portion 41 and the guide pulley 42 is wound. (rack, rod, etc. / specific structure will be described later), or pushed forward (the direction in which the metal pipe 1 is propelled), but the compression drive unit 41 generates a force against the winding or propulsion (pullback force) Or braking force). The pull-back force acts on the metal tube 1 through the guide wheel 42 and the clamp arm 21 to compress the tube wall, thereby suppressing the wall thickness reduction of the peripheral portion of the tube. Further, in the above-described apparatus configuration, the compression drive unit 41 for generating the pull-back force is disposed on the outer side of the metal pipe 1 as viewed from the side of the support shaft A, and the support shaft A to the pull-back force which is the fulcrum of -13 to 200924870 The distance R2 at which the point (force point) B is applied is larger than the distance R1 from the support axis to the point of application of the compressive force, that is, the holding point (clamping portion 22) of the metal pipe 1 of the clamp arm 21. Therefore, with the lever principle with the fulcrum A as a fulcrum, it is possible to apply a large compressive force to the metal pipe 1 even with a small pulling back force. Further, the features of the structure of the device are as follows. [Device Operation] When the drive drive unit 31 and the compression drive unit 41 are driven to start bending, as described above, the base 51 advances toward the support A side, and the forward speed is V1. Further, the advancement of the base 51 advances the point (heating point) P heated by the heating coil 11, and the rotation of the clamp arm 21 causes the hot spot P to be wound around the support axis A (refer to Fig. 1B). Further, the heating coil 11 is not moved, and the tube portion (heating point) heated by the heating coil 11 is continuously subjected to plastic processing in the order of rapid cooling after being bent and deformed by a coolant such as water or compressed air. Fig. 2 is a view showing displacements in the tube axis direction at respective points (the support axis A, the heating point P, the pullback force application point B, and the base X?) of the apparatus when the elapsed time 11 has elapsed. As shown in the figure, the base 51 is moved from the initial position X〇 toward the support axis A by only VlXtl. Further, when the speed of the heating point P which advances with the advancement of the base 51 is V, the forward speed is ¥ in the metal. When the compression ratio of the tube 1 is β, it is expressed by the following equation, and the forward speed V is the processing speed. v = Vj · β ) (1) Formula-14 - 200924870 In addition, at this time, the engagement point (the pulling force application point) B of the compression driving portion 41 that is simultaneously engaged with the guide pulley 42 also advances. The forward speed V2 is controlled by the compression drive unit as shown in the following equation. V2=Vi· R2/R1 (2) From the above equations (U) and (2), the following equation (3) can be derived, and the displacement of the above-mentioned points A, P, and B associated with the clamping arm 21 is balanced. In the other '1B and 2', the points at which the points p and b are shifted (t=t!) are denoted by X! and B!, respectively. The fulcrum A is fixed so that there is no displacement. - Bi and p- Ρι actually have a circular arc shape, but are represented by a straight line in Fig. 2. V2 / v = R2 / R1 (3) In the above operation, the drive point 31 is used to point A (support) The tension F1 formed by the shaft generating reaction force causes the base 51 to be driven forward at the speed Vi (refer to FIG. 1A). As the base 51 advances, the same thrust as the tension F1 is applied to the rear portion of the metal pipe 1. F1 is applied to the outer periphery of the guide wheel 42 (the front end portion of the clamp arm 21) by the tension F2 formed by the reaction of the compression drive unit 41 against the base 51. The above-mentioned thrust F1 is in addition to the pull. The return force F2 has a static equilibrium relationship, and also includes a bending deformation resistance fb including the metal pipe 1 or a compression deformation resistance fp' of the metal pipe 1, plus the processing device The dynamic frictional force f/z generated by the movement of the various elements is a dynamic balance relationship with the forward movement of the metal pipe speed 乂! -15- 200924870. In addition, the compressive deformation resistance fp is equal to the compression force Fp among the loads. Dynamic balance. The above-mentioned bending deformation resistance fb or compression deformation resistance fp is a necessary force for the purpose of processing. Moreover, it is not easy to become a force that disturbs the processing action. The reason is that the coaxial action acts on the metal tube. 1, the deformation resistance is a stable enthalpy determined by the temperature. In contrast, the dynamic frictional force fy φ generated by the movement of the device element acts on the metal tube 1 on the different axis, and otherwise Dry friction in low-speed operation like bending, so that the boundary friction becomes dominant and irregular. The amplitude changes frequently, so the machining operation is easily disturbed. However, the structure of the device has the advantage that the above-mentioned different-axis force can be sandwiched. The metal tube 1 acts in a see-saw-like shape so that most of the different axial forces are offset (even if not completely offset, it can be reduced considerably) In addition to the above-described structure, the pusher drive unit 31 and the compression drive unit 41 are arranged in a state like a tilting plate sandwiching the metal pipe 1 as described above. The base 51 and the clamp arm 21 sandwich the metal tube 1 to exert a propulsive force and a compressive force to form a so-called "closed structure". Therefore, other fixed points (basis) are not required except for fixing the support shaft A in advance. The miniaturization of the entire apparatus is also one of the advantages. Hereinafter, a more specific apparatus configuration example of the present invention will be described. [Embodiment 1] Figs. 3A to 3B are diagrams showing the first embodiment of the present invention-16 - 200924870 Off bending machine. As shown in the figures, the bending apparatus includes a heating coil 11 that can heat the metal pipe 1 which is a bending target, a power supply unit 12 that can supply a high-frequency current to the heating coil 11, and a metal pipe that can hold the metal pipe a clamping arm 21 for rotating the front end portion; a base 51 for holding the rear portion of the metal tube 1 toward the heating coil 11; a pushing drive portion 31 for advancing the base 51; and a compression driving portion 41 for applying a compressive force to the metal tube 1; And the pedestal 10 which supports the base 51 while being fixed to the fulcrum A so that the base 51 can advance toward the fulcrum A. The clamp arm 21 is provided with a front clamp portion 22 that can grip the position immediately before the heating portion of the metal pipe 1 heated by the heating coil 11, and is provided to be rotatable about the support shaft A. The heating coil 11 is inductively heated by the high-frequency current supply from the power supply unit 12 in this example, but is not limited to the induction heating coil. For example, a gas burner may be used. Other heating means. The base 51 is provided with a rear clamp portion Q 52 which can hold the rear portion of the metal pipe 1, and is provided on the pedestal 10 fixed to the support shaft A so as to be able to advance linearly (straight) toward the heating coil 11 and the support shaft A. The base 51 (hence the metal pipe 1 held by the base 51) is propelled by the propulsion drive unit 31 toward the heating coil 11 and the support A. The propulsion drive unit 31 is constituted by a cylinder (for example, a hydraulic cylinder) 32 fixed to the pedestal 10, and a piston rod 33 provided in the cylinder 33 is connected to a rear end portion of the base 51 to thereby abut the base 51. Apply propulsion. Further, in this example, the base 51 is propelled by the two cylinders 32, but one or three or more cylinders may be provided. Further, the front clamping portion -17-200924870 22 and the rear clamping portion 52 may be, for example, a collet chuck, but any mechanism capable of holding the metal pipe 1 is not limited. Chuck or clamp mechanism. On the other hand, the compression drive unit 41 is constituted by a cylinder (for example, a hydraulic cylinder) 43 fixed to the base 51, and a rack 45 is provided at the tip end of the piston rod 44 provided in the cylinder 43 to be attached to the rack 45. The engaged teeth are disposed on the periphery of the guide wheel 42. The guide pulley 42 is constituted by a pinion gear provided at the outer periphery of the Q tooth engageable with the rack 45 as described above, and is fixed to the clamp arm 21 so as to be rotatable about the support shaft A together with the clamp arm 21. Therefore, when the metal pipe 1 is propelled, the clamp arm 21 rotates, causing the guide wheel 42 and the clamp arm 21 to rotate together to cause the rack 45 to advance forward (toward the same direction as the metal pipe 1) (refer to FIG. 3B) However, the cylinder 43 for constituting the compression drive unit 41 is a pulling force that causes the rack 45 to move in the opposite direction to the rack 45. As a result, the compression force can be applied to the metal pipe 1 in the tube axis direction through the pinion (guide wheel) 42, the clamp arm 21, and the front clamp portion 22. In the present embodiment, according to the present invention, the above-described compression driving portion 41 is disposed on the opposite side of the support shaft A with the metal tube (the metal tube portion before processing) interposed therebetween, and the support shaft A to the compression driving portion 41 (pullback force) The distance R2 of the application point, that is, the nip portion of the rack 45 and the pinion gear 42 is smaller than the distance between the support shaft A and the grip portion (the front clamp portion 22) of the metal pipe 1 (or, the support shaft A and the heating coil 1 1) Since the distance R1 of the heated heating portion is also large, it is possible to effectively apply a compressive force to the metal pipe 1 with a small pulling back force, and it is possible to suppress the thickness reduction of the pipe wall during the bending process. -18-200924870 [Embodiment 2] Fig. 4 is a view showing a bending apparatus relating to a second embodiment of the present invention. As shown in the figure, the bending apparatus is provided with a heating coil 11 for heating the metal pipe 1, a power supply unit 12, a clamp arm 21, a base 51, and a propulsion drive unit 31 (propulsion cylinder). The cylinder 32 and the piston rod 33), the compression drive unit 41 (the compression cylinder 43, the piston rod 44, and the rack 45), the guide wheel (pinion) 42, the support shaft A, and the pedestal 10, but 0 and the first implementation described above The difference is that the cylinder 32 of the propulsion drive unit 31 is fixed to the base 51, and the front end portion of the piston rod 33 of the propulsion drive unit 31 is fixed to the support shaft A, and is pulled into the propulsion cylinder 32 by the piston rod 33. The base 51 is brought to the support axis A for advancement. Further, in the propulsion direction of the metal pipe 1, the fulcrum A and the propulsion drive unit 3 are disposed on one side of the metal pipe 1, and the compression drive unit 41 is disposed on the other side, and the fulcrum A can be made in the same manner as the first example described above. The squeezing distance R2 of the compression driving portion 41 (the urging portion of the pulling force, that is, the nip portion of the rack 45 and the pinion gear 42) is larger than the distance R1 between the fulcrum A to the grip portion (the front clamping portion 22) of the metal pipe 1. The other configuration is the same as that of the first embodiment described above, and therefore, the same reference numerals are used to omit the repeated description in the drawings (the third embodiment is also the same). [Embodiment 3] Fig. 5 is a view showing a bending apparatus according to a third embodiment of the present invention. As shown in the figure, the bending apparatus is the same as the first embodiment, and includes a heating coil 11, a power supply unit 12, a clamp arm 21, a base 51, and a -19-200924870 propulsion drive unit 31 (propulsion cylinder 32). And the piston rod 33), the compression drive unit 41 (the compression cylinder 43, the piston rod 44, and the rack 45), the guide wheel (pinion) 42, the fulcrum A, and the pedestal 10, but different from the above-described first embodiment When the heating portion of the metal pipe 1 heated by the heating coil 11 [or the holding point of the metal pipe 1 of the clamp arm 21 of the initial device (when the machining is started) is used as a reference, the compression drive portion is disposed on the same side of the support shaft A. 41. The compression drive unit 41 has a cylinder 43 for compression and a piston rod 44 having a rack 45 at its distal end, but the compression cylinder 43 is not fixed to the pedestal 10 or the support shaft A. Instead, it is fixed to, for example, a floor by a fixed anchor 46. The rack 45 is engaged with a pinion (guide wheel) 42 that rotates around the fulcrum A with the clamp arm 2 1 , and retreats rearward with the advancement of the metal pipe 1 (base 51), but the compression cylinder The cylinder 43 is capable of generating a force (pullback force/braking force) in the opposite direction (frontward), thereby applying a compressive force in the tube axis direction to the metal pipe 1 through the rack 45, the pinion gear 42, and the clamp arm 21. . Further, in this embodiment, similarly, the distance R2 from the support shaft A to the compression driving portion 41 (the application point of the pulling back force, that is, the nip portion of the rack 45 and the pinion gear 42) is the ratio of the support shaft A to the metal tube 1 The distance of the grip portion (front clamp portion 22) (or the distance between the support shaft A and the heating portion heated by the heating coil 11) is also large. The embodiments and examples of the present invention have been described above, but the present invention is not limited thereto, and it should be understood that those skilled in the art can make various modifications within the scope of the claims. For example, in the above embodiment, the mechanism for applying a compressive force to the metal pipe -20-200924870 (compression drive portion, guide wheel) uses a rack and a pinion, but a chain and a sprocket may be used, or Use steel wire and winding drums (drums), or use other power transmission mechanisms. In addition, the clamping means for gripping the metal pipe is a mechanism that can withstand the bending moment applied to the metal pipe and does not cause slip in the axial direction force (the thrust in the pipe length direction) with respect to the pipe axis direction. It may be various mechanisms other than the above. In addition, the other mechanisms and structures other than the examples shown in the drawings may be used for the other propulsion driving portions, the clamp arms, and the moving base. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a view showing a structure of an apparatus (an initial state before processing starts) according to an embodiment of the present invention. Fig. 1B is a view showing a structure of a device (a state in processing) according to an embodiment of the invention. Fig. 2 is a view showing the operation of the above-described device structure (the state when the elapsed time 〇 U from the start of machining). Fig. 3A is a view showing a bending apparatus (initial state before starting the machining) according to the first embodiment of the present invention. Fig. 3B is a view showing a bending apparatus (state during processing) according to the first embodiment of the present invention. Fig. 4 is a view showing a bending apparatus according to a second embodiment of the present invention. Fig. 5 is a view showing a bending apparatus according to a third embodiment of the present invention. -21 - 200924870 [Description of main component symbols] A: Support shaft 1: Metal tube (bending object I 0 : pedestal II: heating coil 1 2: power supply unit © 21: clamp arm 22: front clamp portion 31: Propulsion drive unit 3 2 : propulsion cylinders 33 and 44 : piston rod 41 : compression drive unit 42 : guide pulley (pinion gear) 4 3 : compression cylinder bore 45 : rack 46 : fixed misalignment screw inspection 51 : Moving base 52: rear clamping part-22