201143924 六、發明說明： 【發明所屬之技術領域】 本發明’是關於利用冷拉加工從熱間製管成型的胚管 製造出小徑薄壁無縫鋼管之製造方法。更詳細地說，本發 明’是關於不具有內面毛縫的小徑薄壁管之製造方法。 另’除了有特別記載以外，本說明書之用語定義如下 述。 「小徑薄壁管」：是指熱間製管所獲得的胚管經冷拉 加工後所成品之指定尺寸的無縫鋼管，其冷拉加工後的壁 厚/外徑（T/D )之比爲5〜1 5 %，外徑爲2 0〜3 0mm，壁厚 爲 1.0 〜3.5mm。 【先前技術】 冷間精整的無縫鋼管，是將實心的鋼條經由曼內斯曼 製管法或尤金製管法之熱間製管成爲空心的胚管後，對胚 管進行冷拉加工後製成。曼內斯曼製管法，是對鋼條進行 曼內斯曼穿孔，然後使用定徑機或減徑機定徑或縮徑壓延 成胚管。對所獲得的胚管施以冷拉加工。冷拉加工的主要 目的，是提昇外徑暨內徑暨壁厚的尺寸精度，和，確保機 械性強度，及，提昇內面平滑性。即，減少鋼管內表面的 瑕疵也是冷拉加工處理之一大目的。 經由冷拉加工精整後的無縫鋼管，其用途爲設備的配 管用' 機械構造用等，有時做爲汽車用鋼管使用。用途爲 安全氣囊時，無縫鋼管是做爲壓力容器使用，由於是在封 -5- 201143924 入有高壓氣體的狀態下使用，因此無縫鋼管內表面的瑕疵 不利於做爲壓力容器。 於是，當熱間製管所獲得之胚管的內表面形成有條狀 的瑕疵（以下，又稱「內面毛縫」）時，是需要利用冷拉 加工減少或去除內面的毛縫。 此外，安全氣遜的壓力容器，是需要小型且輕型，因 此安全氣a用鋼管是使用小徑薄壁管。 然而，當利用冷拉加工減少暨去除內面毛縫時，如下 式（1 )所示壁厚加工度愈大則內面毛縫去除效果愈大。 TD = (T，-Τ)/Τ，X 1 00 ... (1 ) 其中，壁厚加工度爲TD(%)，冷拉加工前的鋼管壁厚 爲T’（mm)，冷拉力□工後的鋼管壁厚爲T(mm)。 第1圖，是表示使用錐形模和半浮栓塞之冷拉加工模 式圖。第1圖中，是圖示著錐形模1，和，插入在胚管（拉 加工前的鋼管）內面的栓塞2，及，要冷拉加工的胚管3, 以胚管朝標有斜線的箭頭符號方向移動進行冷拉加工。錐 形模1，是具備：爲了將管材引導至模具出側，入側的模 具內徑爲縮小之錐形的誘導部1 a ;具有一定內徑可決定管 材加工形狀的軸承部1 b ;及出側的逃逸部份1 c。錐形模的 誘導部la的形狀，是由兩角cxf)規定。 半浮栓塞2，是具備：由保持在未圖示固定端的支撐 棒2c固定在加工位置，能夠防止胚管壁厚加工造成栓塞位 置偏移的錐形部2a ;及可規定管成品內徑的精整部2b。半 浮栓塞2的錐形部形狀，是由兩角β〇規定。 201143924 在使用錐形模1和半浮栓塞2進行冷拉加工的處理中’ 胚管3是隨著與錐形模之誘導部1 a的接觸形成縮徑後’又 與半浮检塞2之錐形部2 a接觸使壁厚受到加工。然後’胚 管3，是經由錐形模的軸承部1 b和半浮栓塞2的精整部2 b加 工壁厚使其成品爲指定之外徑及內徑尺寸的無縫鋼管。 對於半浮栓塞2，在冷拉加工時是會作用有隨著胚管 加工產生在冷拉方向的摩擦力。此外’對於半浮栓塞2 ’ 在利用錐形部2 a和錐形模之誘導部1 a對胚管進行壁厚加工 時，是會作用有第1圖之空白箭頭符號所示方向的反力。 半浮栓塞2是由支撐棒2c固定在加工位置’但反力之 冷拉方向的成份爲較小時，摩擦力會造成支撐棒2c變形’ 使半浮栓塞2從加工位置偏移，導致振動產生或胚管斷裂 等抽拉不良。因此，爲了穩定進行冷拉加工，最好是反力 之冷拉方向的成份和摩擦力相等，藉此抑制支撐棒2c的彈 性變形。 先前以來，關於使用錐形模和半浮栓塞之冷拉加工， 是有各種提案。例如：專利文獻1中，是提案有能夠使栓 塞位置成爲穩定性的冷拉加工方法。專利文獻1所提案的 冷拉加工方法，是將模具之誘導部的兩角（模具兩角）α(。 )和栓塞之錐形部的兩角（栓塞兩角）β(。）滿足下述式（2 )及式（3 )，藉此使上述的反力之冷拉方向成份和摩擦 力形成均衡，能夠防止栓塞位置朝冷拉方向偏移的同時， 倉g夠防止胚管對模具產生熱黏砂及能夠防止胚管的斷裂。 1 5 ^ α ^ 30 ...(2) -7- 201143924 α-10^β^α-3 ---(3) 當將專利文獻1所提案的冷拉方法使用在小徑薄壁之 無縫鋼管的製造時，即使滿足上述式（2 )但模具兩角有 些角度還是會造成所獲得的小徑薄壁管殘留有內面毛縫。 如以上所述，內面毛縫的去除效果，是壁厚加工度愈 大愈高，因此爲了防止內面毛縫的殘留，是可考慮將胚管 壁厚加厚，但胚管的壁厚和冷拉加工後的鋼管壁厚之厚度 比太大時，是會在冷拉加工時產生振動或胚管斷裂，無法 穏定進行冷拉加工。因此，針對小徑薄壁管的冷拉加工處 理，胚管的壁厚是無法增加太厚。 專利文獻2，是關於壁厚/外徑（T/D )的比爲20%以上 之厚度的無縫鋼管之內面毛縫的減少，提案有是將油潤滑 後或化成皮膜潤滑後的胚管根據可滿足壁厚加工度和模具 角度所規定之條件式的加工條件進行冷拉加工的方法。 專利文獻2所提案之冷拉方法的對象，是厚壁的鋼管 ，所以即使胚管的壁厚爲較厚，但冷拉加工前後的壁厚比 並不大，因此只要滿足專利文獻2所記載的條件式，就可 獲得良好的結果。然而，製造小徑薄壁管時，因胚管的厚 度是無法如上述增加太厚，所以即使滿足專利文獻2所記 載的條件式，但模具角度有些角度還是會造成內面毛縫的 殘留。 [先行技術文獻] [專利文獻] [專利文獻1]曰本特開2006-272396號公報 201143924 [專利文獻2]日本特開2002-361319號公報 【發明內容】 [發明欲解決之課題] 如以上所述，若使用先前所提案的冷拉方法’對熱間 製管製成的胚管進行冷拉加工製造小徑薄壁的無縫鋼管時 ，即使滿足先前提案的條件但還是會產生模具角度有些角 度無法去除熱間製管所形成之內面毛縫的問題。本發明， 是有鑑於上述狀況而爲的發明，目的是提供一種不會殘留 有內面毛縫的小徑薄壁管之製造方法。 [用以解決課題之手段] 爲了解決上述問題，進行不使用栓塞只利用錐形模進 行胚管冷拉加工之「空拉」的冷拉試驗，確認出錐形模之 誘導部的兩角對胚管壁厚的影響。本試驗是對誘導部的兩 角α爲20°、25°及3 0°時壁厚/外徑（t/d )的比和增厚率之 關係進行了調查。於此，增厚率TW(%)在胚管厚度爲T， (mm ) ’胚管空拉之冷拉後的壁厚爲T ( mm )時，用下 式（4 )就能夠算出 TW = (T-T，）/T，X 1 〇〇 (4) 本試驗中的試驗條件如以下所述。 胚管的規格：壁厚/外徑=7%〜9〇/。 材質 Cr-Mo鋼（含有c Oj—OJ%、201143924 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a method for producing a small-diameter thin-walled seamless steel pipe by a cold-drawing process from a tube formed by a hot tube. More specifically, the present invention is a method of manufacturing a small-diameter thin-walled tube which does not have an inner surface burr. In addition, unless otherwise specified, the terms used in this specification are defined as follows. "Small-diameter thin-walled pipe": refers to the seamless steel pipe of the specified size of the finished tube obtained by the hot-sleeve pipe after cold drawing, and the wall thickness/outer diameter (T/D) after cold drawing The ratio is 5 to 1 5 %, the outer diameter is 2 0 to 3 0 mm, and the wall thickness is 1.0 to 3.5 mm. [Prior Art] The cold-finished seamless steel pipe is a cold-casting of the metal pipe after the solid steel pipe is made into a hollow metal pipe by the Mannesmann pipe method or the Eugene pipe method. Made after drawing. Mannesmann's pipe making method involves mansmann manhole perforation and then sizing or reducing the diameter into a blank tube using a sizing machine or a reducer. The obtained embryo tube is subjected to cold drawing processing. The main purpose of the cold drawing process is to improve the dimensional accuracy of the outer diameter and inner diameter and wall thickness, and to ensure the mechanical strength and to improve the smoothness of the inner surface. That is, reducing the flaw of the inner surface of the steel pipe is also a major purpose of the cold drawing process. The seamless steel pipe which has been finished by cold drawing is used for piping for equipment, such as mechanical construction, and may be used as a steel pipe for automobiles. When the airbag is used, the seamless steel pipe is used as a pressure vessel. Since it is used in a state where high pressure gas is supplied in the seal -5-201143924, the inner surface of the seamless steel pipe is not suitable as a pressure vessel. Therefore, when the inner surface of the embryo tube obtained by the hot tube is formed with a strip-shaped ridge (hereinafter also referred to as "inner burr"), it is necessary to reduce or remove the crevice of the inner surface by cold drawing. In addition, the pressure vessel with a low safety is required to be small and lightweight, so that the steel pipe for safety gas a is a small-diameter thin-walled pipe. However, when the inner burr is reduced and removed by the cold drawing process, the greater the wall thickness processing degree as shown in the following formula (1), the greater the inner burr removal effect. TD = (T, -Τ) / Τ, X 1 00 (1) where the wall thickness is TD (%), and the wall thickness of the steel pipe before cold drawing is T' (mm), cold tension □ The wall thickness of the steel pipe after work is T (mm). Fig. 1 is a view showing a cold drawing process using a tapered die and a semi-floating plug. In the first figure, the taper die 1 is shown, and the plug 2 inserted into the inner surface of the embryonic tube (the steel pipe before the drawing process) and the embryo tube 3 to be cold drawn are marked with the embryo tube The diagonal arrow symbol moves in the direction of cold drawing. The tapered die 1 includes an inducing portion 1 a for reducing the taper of the inner diameter of the die on the side of the die to guide the pipe to the exit side of the die, and a bearing portion 1 b having a constant inner diameter to determine the shape of the pipe; and The escape part of the exit side is 1 c. The shape of the inducing portion la of the tapered die is defined by the two corners cxf). The semi-floating plug 2 is provided with a tapered portion 2a which is fixed to the processing position by a support rod 2c held at a fixed end (not shown), and can prevent the embolization position from being displaced by the thickness of the tube; and the inner diameter of the tube can be specified. Finishing section 2b. The shape of the tapered portion of the semi-float plug 2 is defined by two angles β〇. 201143924 In the process of cold drawing using the tapered die 1 and the semi-floating plug 2, the 'the embryonic tube 3 is formed after the diameter reduction with the contact portion 1 a of the tapered die' and the semi-floating plug 2 The contact of the tapered portion 2a causes the wall thickness to be processed. Then, the 'raw tube 3' is a seamless steel pipe having a predetermined outer diameter and an inner diameter dimension by processing the thickness of the bearing portion 1 b of the tapered die and the finishing portion 2 b of the semi-floating plug 2 to a finished product. For the semi-floating plug 2, during the cold drawing process, the frictional force in the cold drawing direction with the processing of the embryonic tube is exerted. Further, in the case of the semi-floating plug 2', when the wall thickness is processed by the taper portion 2a and the inducing portion 1a of the tapered mold, the reaction force in the direction indicated by the blank arrow symbol in Fig. 1 acts. . The semi-floating plug 2 is fixed by the support rod 2c at the processing position 'but when the composition of the cold drawing direction of the reaction force is small, the frictional force causes the support rod 2c to be deformed', and the semi-floating plug 2 is displaced from the processing position, resulting in vibration. Poor extraction such as rupture of the embryo or tube. Therefore, in order to stably perform the cold drawing process, it is preferable that the composition in the cold drawing direction of the reaction force and the frictional force are equal, thereby suppressing the elastic deformation of the support rod 2c. Previously, there have been various proposals for cold drawing processing using a tapered die and a semi-floating plug. For example, Patent Document 1 proposes a cold drawing processing method capable of making the plug position stable. In the cold drawing processing method proposed in Patent Document 1, the two corners (the two corners of the mold) α (.) of the induction portion of the mold and the two corners (the two angles of the plug) β (.) of the tapered portion of the plug satisfy the following. Formula (2) and formula (3), thereby balancing the cold drawing direction component and the frictional force of the above-mentioned reaction force, and preventing the embedding position from shifting toward the cold drawing direction, and the cartridge g can prevent the embryonic tube from being generated on the mold. Hot clay and can prevent the breakage of the embryonic tube. 1 5 ^ α ^ 30 (2) -7- 201143924 α-10^β^α-3 --- (3) When the cold drawing method proposed in Patent Document 1 is used in the small-diameter thin wall When the seam steel pipe is manufactured, even if the above formula (2) is satisfied, some angles at both corners of the mold may cause the inner diameter burr to remain in the obtained small-diameter thin-walled tube. As described above, the removal effect of the inner surface burr is that the wall thickness processing degree is higher and higher, so in order to prevent the residual of the inner surface burr, it is conceivable to thicken the wall thickness of the embryo tube, but the wall thickness of the embryo tube When the thickness ratio of the wall thickness of the steel pipe after cold drawing is too large, vibration or tube breakage occurs during cold drawing, and cold drawing processing cannot be determined. Therefore, for the cold drawing processing of small-diameter thin-walled tubes, the wall thickness of the raw tube cannot be increased too thick. Patent Document 2 relates to a reduction in the inner surface crevice of a seamless steel pipe having a thickness of the wall thickness/outer diameter (T/D) of 20% or more, and is proposed to be an oil after lubricating the oil or after being lubricated by the film. The tube is subjected to a cold drawing process according to a processing condition that satisfies the conditions of the wall thickness processing degree and the mold angle. The object of the cold drawing method proposed in the patent document 2 is a thick-walled steel pipe. Therefore, even if the thickness of the raw pipe is thick, the thickness ratio before and after the cold drawing is not large, so that the patent document 2 is satisfied. The conditional formula can give good results. However, in the case of manufacturing a small-diameter thin-walled tube, since the thickness of the embryonic tube cannot be increased too much as described above, even if the conditional expression described in Patent Document 2 is satisfied, the angle of the mold angle may cause the inner surface burr to remain. [PRIOR ART DOCUMENT] [Patent Document 1] JP-A-2006-272396 (Patent Document 2) JP-A-2002-361319 SUMMARY OF INVENTION [Problems to be Solved by the Invention] According to the cold drawing method previously proposed, the cold-drawn drawing of the raw tube made of the heat-made tube is used to manufacture a small-diameter thin-walled seamless steel pipe, and even if the conditions of the previously proposed conditions are satisfied, the mold angle is generated. Some angles do not remove the problem of the inner burrs formed by the heat pipe. The present invention has been made in view of the above circumstances, and an object of the invention is to provide a method for producing a small-diameter thin-walled tube which does not have an inner surface burr. [Means for Solving the Problem] In order to solve the above problem, a cold drawing test of "empty pulling" of the cold drawing of the embryo tube using only the taper die is performed without using the plug, and the two corner pairs of the inducing portion of the tapered die are confirmed. The effect of the wall thickness of the embryo. In this test, the relationship between the ratio of the wall thickness/outer diameter (t/d) and the thickening ratio at the two angles α of the induction portion of 20°, 25°, and 30° was investigated. Here, the thickening ratio TW (%) can be calculated by the following formula (4) when the thickness of the embryonic tube is T, (mm), and the wall thickness after the cold drawing of the embryonic tube is T (mm). (TT,) / T, X 1 〇〇 (4) The test conditions in this test are as follows. Specification of the embryo tube: wall thickness / outer diameter = 7% ~ 9 〇 /. Material Cr-Mo steel (containing c Oj-OJ%,
Cr 〇 · 5 〜0 · 7 %、 -9- 201143924Cr 〇 · 5 ～0 · 7 %, -9- 201143924
Mo 0.3 〜0.4% ) 冷拉管規格：壁厚/外徑=8%〜10% 第2關，是圖示著只使用錐形模進行空拉來獲 薄壁管時的壁厚/外徑（T/D )的比（％ )和增厚率 之關係圖。根據第2圖’可確認出增厚率TW(%)爲 透過本試驗得知，小徑薄壁管藉由使用錐形模進行 空拉），可使壁厚增加（增厚）。此外’又得知將 的兩角α形成爲較小’則能夠使增厚率TW(%)增加。 本發明人是基於上述的試驗結果’獲得以下 〜（c )項的知識。 (a )對小徑薄壁管施以使用模具及栓塞的冷 時，於錐形模的誘導部’被處理管的壁厚會一旦增 厚），然後，於軸承部（由相向之栓塞的精整部夾 出），被處理管的壁厚會減少（減厚）最終成爲加 壁厚（目標値的壁厚）。 (b )此外，若將錐形模之誘導部的兩角形成 時，被處理管的壁厚於該誘導部的增厚量會增加（ 成更厚）。 (c)因此，冷拉加工前之鋼管（胚管）的壁 拉加工後之鋼管的壁厚即使爲一定’但藉由將錐形 導部的兩角形成爲較小’於該誘導部’鋼管的壁厚 增加，因此就能夠增加實質的壁厚加工度。基於此 能提高內面毛縫的去除效果。 本發明是根據上述的知識及下述的確認試驗結 得小徑 T W ( %) 正値。 冷拉（ 誘導部 (a )項 拉加工 加（增 持著拉 工後的 爲較小 壁厚變 厚及冷 模之誘 會一旦 ，有可 果完成 -10- 201143924 ’下述（1 )項〜（3 )項的小徑薄壁管之製造方法爲其主 @。 (1 )小徑薄壁管之製造方法’使用：做爲加工用模 具而具備有錐形誘導部和冷拉外徑決定用軸承部的錐形模 :及 插入在由上述錐形模進行一邊縮徑一邊冷拉加工之管 其內面的栓塞進行小徑薄管冷拉加工的無縫鋼管之製造方 法，其特徵爲， 使用上述誘導部的兩角爲1 5 °〜2 0 °的錐形模。 (2 )是於上述（1 )項所記載的小徑薄壁管之製造方 法，其特徵爲，所要使用的栓塞是半浮栓塞，該半浮栓塞 具備有可規定管成品內徑的精整部和與此連設形成的錐形 部。 (3 )是於上述（1 )項或（2 )項所記載的小徑薄壁 管之製造方法，其特徵爲，所要獲得的小徑薄壁管不具有 內面毛縫。 [發明效果] 本發明的小徑薄壁管之製造方法，具有下述明顯的效 果。 (1 )根據使用錐形模和栓塞的冷拉加工’是能夠不 用增加胚管壁厚，就能夠減少熱間製管時產生的內面毛縫 ’能夠獲得內面品質優越的小徑薄壁管。 -11 - 201143924 【實施方式】 [發明之最佳實施形態] 以下，是對本發明的小徑薄壁管之製造方法進行說明 0 成爲本發明對象的鋼管，是小徑薄壁管。於此，所謂 小徑薄壁管，是指熱間製管所獲得的胚管經冷拉加工後所 成品之指定尺寸的無縫鋼管，其冷拉加工後的壁厚/外徑 (T/D )之比爲5〜1 5%，外徑爲20〜30mm，壁厚爲】·〇〜 3.5mm ° 當鋼管冷拉加工後的壁厚/外徑（T/D )之比超過1 5% 或壁厚超過3 . 5 m m時，利用先前的冷拉加工方法就能夠減 少內面毛縫，沒有必要採用本發明的小徑薄壁管之製造方 法。另一方面，當鋼管冷拉加工後的壁厚/外徑（T/D )之 比未滿5 %或壁厚未滿1 . 〇 m m時，是無法確保充分的強度做 爲安全氣逛的壓力容器。鋼管冷拉加工後的外徑爲2 0〜 3 0mm，是基於安全氣逛用鋼管之用途考量^ 小徑薄壁管’是使用Cr-Mo鋼、碳鋼等的各種鋼，但 使用Cr·Mo鋼時’胚管容易產生內面毛縫的同時，冷拉加 工後也容易殘留有內面毛縫。因此，對於由C r - Μ 〇鋼形成 之小徑薄壁管的冷拉加工，最好是採用本發明的小徑薄壁 管之製造方法。 本發明的小徑薄壁管之製造方法，是使用：要做爲加 工用模具而具備有錐形誘導部和冷拉外徑決定用軸承部的 錐形模’及要插入在由上述錐形模進行邊縮徑邊冷拉加工 -12- 201143924 之管其內面的栓塞進行小徑薄管冷拉加工的無縫鋼管之製 造方法’其特徵爲，是使用誘導部的兩角爲15。〜20。的錐 形模。 本發明的小徑薄壁管之製造方法，錐形模之誘導部的 兩角爲1 5 °〜2 0°。從上述第2圖所示的結果，得知於小徑薄 壁管的空拉若誘導部的兩角爲較小則增厚率TW ( % )會增 加。因此，有使用栓塞的冷拉加工，藉由將誘導部的兩角 形成爲較小，是能夠在誘導部實現胚管（被冷拉的管）的 增厚，使胚管於軸承部的加工能夠實質性增加壁厚加工度 。即，就算冷拉加工前的鋼管（胚管）壁厚及加工後的鋼 管壁厚爲一定時（換句話說，即使不增加胚管的壁厚）， 但於該誘導部，胚管壁厚會一旦增加，因此於軸承部的加 工就能夠確保實質性的壁厚加工度，能夠減少所獲得之無 縫鋼管的內面毛縫。 當錐形模之誘導部的兩角超過20°時，錐形模造成的 增厚率T W會減少，因此於軸承部的加工就無法確保壁厚 加工度，導致所獲得之無縫鋼管殘留有內面毛縫。另一方 面，當誘導部的兩角未滿〗5 °時，由於誘導部和胚管之接 觸距離會增加，所以容易產生潤滑不良造成的振動。於該 狀況時，所獲得之無縫鋼管的內面品質就會變差。 本發明的小徑薄壁管之製造方法’栓塞’是可使用圓 筒形栓塞、半浮栓塞、浮塞等各種栓塞’但以使用半浮栓 塞爲最佳。栓塞若使用半浮栓塞時’是可使栓塞穩定配置 在加工位置，能夠抑制抽拉不良。 -13- 201143924 本發明的小徑薄壁管之製造方法中’使用半浮栓塞時 ，錐形部的兩角是以可滿足下述式（3)的値爲最佳。 α-1 0 ^ β ^ α-3 …（3) 於此，錐形模之誘導部的兩角爲α(°) ’栓塞之錐形部 的兩角爲β(Ί。 當誘導部的兩角爲α和錐形部的兩角爲β之差大於1 〇 ° 時，即，β<α-1 0時，冷拉加工時作用在栓塞的反力其冷拉 方向的成份會減少。因此’栓塞的位置會隨著胚管的冷拉 而朝冷拉方向偏移，所以有時就會產生抽拉不良。另一方 面，當誘導部的兩角爲α和錐形部的兩角爲β之差小於3°時 ，β>α-3時，錐形部的後端會咬入在胚管的內面，使栓塞 的位置朝冷拉方向偏移，因此就容易產生抽拉不良。 如以上所述，安全氣遜所使用的小徑薄壁管，是在封 入有高壓氣體的狀態下使用，因此最好不要有內面毛縫^ 本發明的小徑薄壁管之製造方法，即使胚管的壁厚沒有形 成太厚’也能夠確保實質性的壁厚加工度，因此就能夠穏 定進行冷拉加工，並且能夠去除小徑薄壁管的內面毛縫。 [贲施例] 根據本發明的小徑薄壁管之製造方法，進行了熱間製 管之胚管經冷拉加工後獲得小徑薄壁管的試驗，驗證了本 發明的效果。 [試驗方法] -14- 201143924 使用上述第1圖所是的錐形模及半浮栓塞，對胚管施 以冷拉加工使其成爲冷拉管。其條件如下述。 胚管的規格：外徑3 1.80mm、壁厚2.9 0mm 材質 Cr-Mo鋼（含有C 0.1〜0.2%、 C r 0.5 〜0 · 7 %、Mo 0.3 ~0.4%) Cold drawn tube specification: wall thickness / outer diameter = 8% ~ 10% The second level is the wall thickness / outer diameter when the thin-walled tube is obtained by only using a conical mold for empty drawing. A plot of the ratio (%) of (T/D) and the rate of thickening. According to Fig. 2, it can be confirmed that the thickening ratio TW (%) is obtained by the test, and the small-diameter thin-walled tube is air-drawn by using a tapered die to increase (thickness) the wall thickness. Further, it is known that the two corners α are formed to be smaller, and the thickening ratio TW (%) can be increased. The inventors obtained knowledge of the following items (c) based on the above test results'. (a) When a small-diameter thin-walled tube is subjected to cold using a mold and a plug, the thickness of the tube to be treated in the induction portion of the tapered mold is once thickened, and then, in the bearing portion (plugged by the opposite side) When the finishing part is clamped out, the wall thickness of the treated pipe is reduced (thickened) and finally becomes the wall thickness (the wall thickness of the target 値). (b) Further, when the two corners of the inducing portion of the tapered mold are formed, the thickness of the tube to be treated which is thicker than the thickness of the inducing portion is increased (to be thicker). (c) Therefore, the wall thickness of the steel pipe after the wall drawing process of the steel pipe (raw tube) before the cold drawing process is even 'but by forming the two corners of the tapered guide portion to be smaller 'in the induction portion' steel pipe The wall thickness is increased, so that substantial wall thickness processing can be increased. Based on this, the removal effect of the inner face seam can be improved. The present invention is based on the above knowledge and the following confirmation test to obtain a small diameter T W (%). Cold drawing (induction part (a) item processing plus (increased holding of small wall thickness thickening and cold mold after the pull, once the fruit can be completed -10- 201143924 ' following item (1) The manufacturing method of the small-diameter thin-walled tube of the item (3) is the main one. (1) Manufacturing method of the small-diameter thin-walled tube 'Use: As a processing die, it has a tapered induction portion and a cold drawn outer diameter. A method for producing a seamless steel pipe in which a small-diameter thin tube is cold-drawn by inserting a taper mold of a bearing portion and a plug which is inserted into a tube of a tube which is subjected to a cold-drawing process while being reduced in diameter by the tapered mold; A method of manufacturing a small-diameter thin-walled tube according to the above item (1), wherein the method of using the tapered portion of the small-diameter tube according to the above item (1) is used. The plug is a semi-floating plug having a finishing portion that defines an inner diameter of the finished tube and a tapered portion formed therewith. (3) is in the above item (1) or (2) The method for producing a small-diameter thin-walled tube according to the invention is characterized in that the small-diameter thin-walled tube to be obtained does not have an inner surface burr. The method for producing a small-diameter thin-walled tube of the present invention has the following remarkable effects. (1) According to the cold drawing process using a tapered mold and a plug, it is possible to reduce the heat-intermediation without increasing the thickness of the raw tube. The inner surface crevice produced in the tube can obtain a small-diameter thin-walled tube having excellent inner surface quality. -11 - 201143924 [Embodiment] [Best Embodiment of the Invention] Hereinafter, the small-diameter thin-walled tube of the present invention is Description of the manufacturing method 0 The steel pipe to be the object of the present invention is a small-diameter thin-walled pipe. Here, the small-diameter thin-walled pipe refers to a specified size of a finished product obtained by cold-drawing a raw pipe obtained by a hot-tubing pipe. The seamless steel pipe has a wall thickness/outer diameter (T/D) ratio of 5 to 1 5% after cold drawing, an outer diameter of 20 to 30 mm, and a wall thickness of 〇·3.5 mm ° when the steel pipe is cold When the ratio of the wall thickness/outer diameter (T/D) after the drawing is more than 1 5% or the wall thickness exceeds 3.5 mm, the inner burr can be reduced by the previous cold drawing processing method, and it is not necessary to adopt the present invention. Method for manufacturing small-diameter thin-walled tubes. On the other hand, when the steel pipe is cold-drawn, the wall thickness/outer diameter (T/D) When the thickness is less than 5% or the wall thickness is less than 1. When 〇mm, it is a pressure vessel that cannot ensure sufficient strength as a safety gas. The outer diameter of the steel pipe after cold drawing is 20 to 30 mm, which is based on safety. The use of steel pipes is considered to be small. The small-diameter thin-walled pipe is made of various steels such as Cr-Mo steel and carbon steel. However, when Cr·Mo steel is used, the inner tube is easy to produce the inner surface crevice, and the cold drawing process is also It is easy to leave the inner burr. Therefore, it is preferable to use the small-diameter thin-walled tube of the present invention for the cold-drawing processing of the small-diameter thin-walled tube formed of C r - 〇 〇 steel. The manufacturing method of the thin-walled tube is to use a tapered mold having a tapered induction portion and a cold-drawn outer diameter determining bearing portion for the processing mold, and to be inserted into the tapered mold The method of manufacturing a seamless steel pipe for cold-drawing a small-diameter thin tube by a plug on the inner side of the tube -12-201143924 is characterized in that the two corners of the use-inducing portion are 15. ~20. Cone shape. In the method for producing a small-diameter thin-walled tube of the present invention, the two corners of the inducing portion of the tapered mold are from 1 5 ° to 20 °. From the results shown in Fig. 2, it is found that the thickening ratio TW (%) is increased when the two corners of the small-diameter thin-walled tube are small. Therefore, there is a cold drawing process using a plug, and by forming the two corners of the inducing portion to be small, it is possible to increase the thickness of the embryo tube (tube that is cold-drawn) in the induction portion, and to enable the processing of the embryo tube in the bearing portion. Substantially increase the wall thickness processing. That is, even if the wall thickness of the steel pipe (male tube) before the cold drawing process and the wall thickness of the steel pipe after the processing are constant (in other words, even if the wall thickness of the metal pipe is not increased), the wall thickness of the embryo tube is small in the induction portion. Once it is increased, the processing of the bearing portion can ensure substantial wall thickness processing, and the inner surface crevice of the obtained seamless steel pipe can be reduced. When the two corners of the inducing portion of the tapered mold exceed 20°, the thickening ratio TW caused by the tapered mold is reduced, so that the processing of the bearing portion cannot ensure the wall thickness processing degree, resulting in the residual seamless steel pipe remaining. Inner seams. On the other hand, when the two corners of the inducing portion are less than 5 °, the contact distance between the inducing portion and the embryo tube increases, so that vibration due to poor lubrication is likely to occur. In this case, the quality of the inner surface of the seamless steel pipe obtained is deteriorated. The method of manufacturing the small-diameter thin-walled tube of the present invention 'plug' can use various plugs such as a cylindrical plug, a semi-floating plug, a float, etc., but it is preferable to use a semi-floating plug. When the plug is used with a semi-floating plug, the plug can be stably placed in the processing position, and the pulling failure can be suppressed. -13- 201143924 In the method of manufacturing a small-diameter thin-walled tube of the present invention, when a semi-floating plug is used, the two corners of the tapered portion are preferably 値 which satisfies the following formula (3). -1-1 0 ^ β ^ α-3 (3) Here, the two corners of the inducing portion of the tapered mold are α (°) 'The two corners of the taper portion of the plug are β (Ί. When the two of the inducing portions When the angle between the angle α and the tapered portion is β greater than 1 〇°, that is, when β < α - 1 0, the component acting on the plug in the cold drawing direction in the cold drawing process is reduced in the cold drawing direction. 'The position of the plug will shift toward the cold drawing direction with the cold drawing of the embryo tube, so the drawing may be poor. On the other hand, when the two corners of the inducing part are α and the two corners of the taper are When the difference of β is less than 3°, when β>α-3, the rear end of the tapered portion bites into the inner surface of the embryonic tube, and the position of the plug is shifted in the cold drawing direction, so that the drawing failure is likely to occur. As described above, the small-diameter thin-walled tube used for the safety gas is used in a state in which a high-pressure gas is sealed, so it is preferable not to have the inner surface burr. The manufacturing method of the small-diameter thin-walled tube of the present invention, Even if the wall thickness of the embryo tube is not formed too thick, the substantial wall thickness can be ensured, so that the cold drawing process can be determined and the small diameter thin wall can be removed. The inner surface burr is applied. According to the method for manufacturing a small-diameter thin-walled tube of the present invention, a test for obtaining a small-diameter thin-walled tube by cold-drawing a raw tube of a hot-seal tube is performed, and the present invention is verified. [Effects of the Invention] [Test Method] -14- 201143924 The cannula is subjected to cold drawing to form a cold drawn tube using the tapered mold and the semi-floating plug as shown in Fig. 1. The conditions are as follows. Specifications: outer diameter 3 1.80mm, wall thickness 2.9 0mm material Cr-Mo steel (containing C 0.1~0.2%, C r 0.5 ~ 0 · 7 %,
Mo 0 · 3 〜0 · 4%) 冷拉管規格：外徑25.05 mm、壁厚2.02mm 錐形模之誘導部的兩角，於本發明例1中是形成爲1 5 ° ’於本發明例2中是形成爲20°，於比較例1中是形成爲25° 。此外，半浮栓塞之錐形部的兩角，於本發明例1中是形 成爲1 0°，於本發明例2中是形成爲]5。，於比較例1中是形 成爲20°。 [評價指標] 本發明例和比較例都是根據目視確認冷拉加工後管的 內面性狀。再加上，本發明例2及比較例1，是將管的冷拉 加工在過程途中停止，切斷該管後，在冷拉方向的複數位 置測定管的壁厚及內面毛縫的深度，算出壁厚比及內面毛 縫的深度比。於此，壁厚比，是指所測定出之管的壁厚爲 T，胚管的壁厚爲Τ’時，T/Τ’所示的値。此外，內面毛縫 的深度比，是指所測定出之內面毛縫深度爲A，胚管的內 面毛縫深度爲A’時，A/A’所示的値。 [試驗結果] -15- 201143924 根據目視確認冷拉加工後之管的內面結果，本發 1及本發明例2，是沒有內面毛縫。另一方面，比較必 內面毛縫的深度是有減少，但還是殘留有內面毛縫。 第3圖，是管之冷拉加工在過程途中停止，該管 後之內面性狀的照片，第3(a)圖爲表示錐形模之誘導 兩角爲25°時的比較例，第3(b)圖爲表示兩角爲20°時 發明例。第3(a)圖及第3(b)圖中，是圖示著冷拉管的 面3 a和管內面3b，管與錐形模之誘導部的接觸開始位 ，和，管與半浮栓塞之精整部的接觸開始位置3e是以 線標示。第3(a)圖及第3(b)圖中，白色想像線所包圍 份爲內面毛縫。 比較例1中，是使用誘導部的兩角爲2 5 °的錐形模 據第3(a)圖，是可確認出形成在胚管的內面毛縫於冷 工後還是殘留著。另一方面，本發明例2，是使用誘 的兩角爲20°的錐形模，根據第3(b)圖，是可確認出冷 工後的內面3b沒有毛縫存在。 第4圖，是表示和第3圖相同管之冷拉加工在過程 停止’針對該管切斷後，管之冷拉方向各位置的壁厚 內面條紋深度比相關圖，第4(a)圖爲表示管之冷拉方 位置的壁厚比，第4(b)圖爲表示管之冷拉方向各位置 面條紋深度比。第4(a)圖及第4(b)圖的橫軸是表示從 的接觸位置至測定位置爲止的距離，錐形模的誘導部 以負（一）表示，錐形模的逃逸部側是以正（+ )表开 根據第4(a)圖，是可確認出相較於錐形模之誘導 明例 切斷 部的 的本 切斷 置3 d 白虛 的部 ，根 拉加 導部 拉加 途中 比及 向各 的內 栓塞 側是 〇 部的 -16- 201143924 兩角爲25°之比較例1，錐形模之誘導部的兩角爲20°之 明例2的軸承部前的壁厚比是較大，即，在誘導部就 增厚。因此，是可確認出軸承部之實質性壁厚加工度 〇 此外，根據第4(b)圖，是可確認出誘導部的兩角 之比較例1，冷拉加工是有使內面毛縫的深度減少， 拉加工後還是殘留有內面毛縫。另一方面，是可確認 形模之誘導部的兩角爲20°之本發明例2，冷拉加工後 面毛縫已去除。 根據以上所述，明確得知利用本發明的小徑薄壁 製造方法，是能夠在誘導部增加胚管的增厚量，於之 壁厚加工中，能夠根據在誘導部之增厚量的增加使壁 工度變大，因此能夠減少冷拉管的內面毛縫，能夠提 獲得之管的內面品質。 [產業上之可利用性] 本發明的小徑薄壁管之製造方法，具有下述明顯 果。 (1 )藉由使用錐形模及栓塞之冷拉加工，是可 增加胚管壁厚，就能夠減少熱間製管時產生的內面毛 能夠獲得內面品質優越的小徑薄壁管。 (2 )將所獲得的小徑薄壁管應用在安全氣襄構 的壓力容器時，因爲不具有內面毛縫，所以耐爆裂性 本發 比較 變大 爲25。 但冷 出錐 ，內 管之 後的 厚加 昇所 的效 不用 縫， 成用 優越 -17- 201143924 因此，根據本發明的製造方法時，是能夠提供汽車安 全氣缀所使用之壓力容器最佳的小徑薄壁管。 【圖式簡單說明】 第1圖爲表示使用錐形模和半浮栓塞之冷拉加工模式 圖。 第2圖爲表示只使用錐形模進行空拉來獲得小徑薄壁 管時壁厚/外徑（T/D )的比和增厚率TW ( % )之關係圖》 第3圖爲管之冷拉加工在過程途中停止，該管切斷後 之內面性狀的照片，第3 (a)圖爲表示錐形模之誘導部的兩 角爲2V時的比較例，第3(a)圖爲表示兩角爲20°時的本發 明例。 弟4圖爲表不管之冷拉加1在過程途中停止，針對該 管切斷後，管之冷拉方向各位置的壁厚比及內面條紋深度 比相關圖，第4(a)圖爲表示管之冷拉方向各位置的壁厚比 ’第4(b)圖爲表示管之冷拉方向各位置的內面條紋深度比 【主要元件符號說明】 1 :錐形模 1 a :誘導部 1 b :軸承部 1 c :逃逸部份 2 :半浮栓塞 -18- 201143924 2 a :錐形部 2b :精整部 2 c :支撐棒 3 :胚管 3 a :胚管切斷面 3 b :胚管內面 3 c :內面毛縫 3 d :與錐形模之接觸開始位置 3 e :與半浮栓塞之接觸開始位置 α :誘導部的兩角 β =錐形部的兩角 -19-Mo 0 · 3 〜 0 · 4%) Cold drawn tube specifications: outer diameter 25.05 mm, wall thickness 2.02 mm The two corners of the induction portion of the tapered mold are formed into 15 ° ' in the present invention example 1 In Example 2, it was formed at 20°, and in Comparative Example 1, it was formed at 25°. Further, the two corners of the tapered portion of the semi-floating plug were formed to be 10° in the inventive example 1 and 5 in the inventive example 2. In Comparative Example 1, it was formed to be 20°. [Evaluation Index] Both the inventive examples and the comparative examples confirmed the inner surface properties of the tube after cold drawing by visual observation. Further, in the second and comparative examples of the present invention, the cold drawing of the tube was stopped in the middle of the process, and after cutting the tube, the wall thickness of the tube and the depth of the inner surface burr were measured at a plurality of positions in the cold drawing direction. Calculate the wall thickness ratio and the depth ratio of the inner face burr. Here, the wall thickness ratio means that the thickness of the tube to be measured is T, and the thickness of the tube is Τ', and 値 is represented by T/Τ'. Further, the depth ratio of the inner surface burr is the 値 indicated by A/A' when the measured inner burr depth is A and the inner burr depth of the embryo is A'. [Test Results] -15- 201143924 The results of the inner surface of the tube after cold drawing were visually confirmed. In the present invention, the present invention 1 and the second embodiment of the present invention have no inner surface burrs. On the other hand, the depth of the internal crevice is reduced, but the inner crevice remains. Fig. 3 is a photograph showing the inner surface property of the tube after the cold drawing process is stopped in the middle of the process, and Fig. 3(a) is a comparative example showing the case where the induction angle of the tapered mold is 25°, and the third example. (b) The figure shows an invention example in which the two corners are 20°. In the third (a) and third (b) drawings, the surface 3 a of the cold drawn tube and the inner surface 3b of the tube are shown, the contact start position of the tube and the inducing portion of the tapered mold, and the tube and the half The contact start position 3e of the finishing portion of the float plug is indicated by a line. In Figures 3(a) and 3(b), the white imaginary line encloses the inner crevice. In Comparative Example 1, the tapered mold of Fig. 3 (a) in which the two corners of the inducing portion were 25 ° was used, and it was confirmed that the inner surface of the embryonic tube was formed after the cold work or the remaining. On the other hand, in the second example of the present invention, a tapered mold having two angles of 20° was used, and according to the third (b) diagram, it was confirmed that the inner surface 3b after the cold was free from burrs. Fig. 4 is a diagram showing the correlation between the depth of the inner wall stripe at each position of the cold drawing direction of the tube after the tube is cut in the process of the cold drawing of the same tube as in Fig. 3, Fig. 4(a) In order to indicate the wall thickness ratio of the cold drawing position of the tube, Fig. 4(b) shows the ratio of the stripe depth of each position in the cold drawing direction of the tube. The horizontal axis of the fourth (a) and fourth (b) diagrams indicates the distance from the contact position to the measurement position, and the inducing portion of the tapered mold is represented by a negative (one), and the escape portion side of the tapered mold is According to the fourth (a) diagram, it is possible to confirm the portion of the cut-off portion of the cut-off portion that is inferior to the tapered portion of the tapered mold, and the root-drawing guide portion In the middle of the bearing, the comparison between the two sides of the lead-in side of the pull-in is 16°, and the two corners of the inducing part of the taper die are 20°. The wall thickness ratio is large, that is, it is thickened at the induction portion. Therefore, it is possible to confirm the substantial wall thickness processing degree of the bearing portion. Further, according to the fourth (b) diagram, Comparative Example 1 in which the two corners of the induction portion can be confirmed, and the cold drawing process has the inner surface burr The depth is reduced, and the inner surface crevice remains after the drawing process. On the other hand, in the second example of the present invention, the two corners of the induction portion of the mold were confirmed to be 20°, and the surface burrs were removed after the cold drawing. According to the above, it is clear that the small-diameter thin-wall manufacturing method of the present invention can increase the amount of thickening of the embryo tube in the induction portion, and in the wall thickness processing, it is possible to increase the amount of thickening in the induction portion. The wall workability is increased, so that the inner surface crevice of the cold drawn tube can be reduced, and the inner surface quality of the obtained tube can be improved. [Industrial Applicability] The method for producing a small-diameter thin-walled tube of the present invention has the following remarkable effects. (1) By using a cold drawing process using a tapered die and a plug, it is possible to increase the wall thickness of the raw tube, and it is possible to reduce the inner surface hair generated during the hot tube production, and to obtain a small-diameter thin-walled tube having excellent inner surface quality. (2) When the obtained small-diameter thin-walled pipe is applied to a pressure vessel of a safety gas-tight structure, since the inner burr is not provided, the bursting resistance is increased to 25. However, the cone is cooled out, and the thickness of the inner tube is not increased by the effect of the thickening. The use is superior. -17- 201143924 Therefore, according to the manufacturing method of the present invention, it is possible to provide the pressure vessel used for the safety of the automobile. Small diameter thin wall tube. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a cold drawing process pattern using a tapered die and a semi-floating plug. Figure 2 is a graph showing the relationship between the wall thickness/outer diameter (T/D) ratio and the thickening ratio TW (%) when a small-diameter thin-walled tube is obtained by only using a tapered die. The cold drawing process is stopped in the middle of the process, and the photograph of the inner surface property after the pipe is cut, and the third (a) is a comparative example in which the two corners of the induction portion of the tapered die are 2 V, and the third (a) The present invention is an example of the invention when the two corners are 20°. Figure 4 is a diagram showing the difference between the wall thickness ratio and the inner stripe depth ratio of the tube in the cold drawing direction after the tube is cut, regardless of the cold pull 1 in the process. Figure 4(a) shows The wall thickness ratio of each position in the cold drawing direction of the tube is shown in Fig. 4(b) as the inner stripe depth ratio at each position in the cold drawing direction of the tube. [Main element symbol description] 1 : Tapered mold 1 a : Inducing part 1 b: bearing portion 1 c : escape portion 2 : semi-floating plug 18 - 201143924 2 a : tapered portion 2b : finishing portion 2 c : support rod 3 : embryo tube 3 a : blank tube cut surface 3 b : Inner surface of the embryonic tube 3 c : inner surface burr 3 d : contact with the taper mold start position 3 e : contact with the semi-floating plug start position α: two angles of the induction portion β = two corners of the tapered portion -19 -