JPH11166673A - Manufacture of high pressure fuel injection pipe and high pressure fuel injection pipe - Google Patents
Manufacture of high pressure fuel injection pipe and high pressure fuel injection pipeInfo
- Publication number
- JPH11166673A JPH11166673A JP6936098A JP6936098A JPH11166673A JP H11166673 A JPH11166673 A JP H11166673A JP 6936098 A JP6936098 A JP 6936098A JP 6936098 A JP6936098 A JP 6936098A JP H11166673 A JPH11166673 A JP H11166673A
- Authority
- JP
- Japan
- Prior art keywords
- pipe
- fuel injection
- peripheral surface
- diameter
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Fuel-Injection Apparatus (AREA)
- Joints With Pressure Members (AREA)
Abstract
Description
【０００１】[0001]
【発明が属する技術分野】本発明はディーゼル内燃機関
にあって、燃料供給路としてシリンダーヘッド側のそれ
ぞれノズルホルダーと燃料ポンプ側とに接続して配置さ
れる管径２０ｍｍ程度以下の比較的細径からなる高圧燃
料噴射管や蓄圧式燃料噴射システムにおけるコモンレー
ルからのフィードパイプなど（以下単に高圧燃料噴射管
という）の製造方法および高圧燃料噴射管に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel internal combustion engine, and has a relatively small diameter of about 20 mm or less which is connected to a nozzle holder and a fuel pump on a cylinder head side as a fuel supply path. The present invention relates to a method for manufacturing a high-pressure fuel injection pipe comprising a high-pressure fuel injection pipe, a feed pipe from a common rail in a pressure-accumulation type fuel injection system (hereinafter simply referred to as a high-pressure fuel injection pipe), and a high-pressure fuel injection pipe.
【０００２】[0002]
【従来の技術】従来、この種のディーゼル内燃機関用高
圧燃料噴射管材としては、本出願人が所有する特公平１
−４６７１２号公報が知られている。この公報記載の高
圧燃料噴射管材は、厚肉の鋼管からなる外管に、内側に
流通路が形成されたステンレス鋼管からなる薄肉の内管
を内挿して、両管に同時かつ一体的な空引きによる伸管
加工を施して内外管を圧嵌して二重金属管を構成したも
のであり、この際内管の肉厚を二重金属管材全体の外径
に対し、１．２ないし８．５％としたものである。2. Description of the Related Art Heretofore, as a high pressure fuel injection pipe for a diesel internal combustion engine of this type, Japanese Patent Publication No.
No. 46712 is known. The high-pressure fuel injection tubing described in this publication has a thin-walled inner tube made of a stainless steel tube having a flow passage formed inside, inserted into an outer tube made of a thick-walled steel tube, so that the two tubes can be simultaneously and integrally vacated. The inner and outer pipes are press-fitted by drawing to form a double metal pipe. At this time, the thickness of the inner pipe is 1.2 to 8.5 with respect to the outer diameter of the entire double metal pipe. %.
【０００３】そしてこの公報記載の高圧燃料噴射管材
は、ＮＯｘの低減や黒煙対策の１つとして噴射時間１〜
２ミリ秒、流速が最大で５０ｍ／ｓｅｃ、内圧６００〜
１０００ｂａｒ（ピーク圧）という現在の燃料の噴射圧
の高圧化に対応した条件で動作させても、内周面におけ
るキャビテーション・エロージョン（以下単にエロージ
ョンという）の発生が防止できるのみならず、繰り返し
高圧疲労に対する耐久性もほぼ満足できるものであっ
た。しかしながら近年ＮＯｘの低減や黒煙対策の条件が
一層厳しくなり、内圧が１２００ｂａｒを超えるような
過酷な噴射条件でも繰返し高圧疲労による破壊が発生し
ない高圧燃料噴射管が要求される傾向となり、特公平１
−４６７１２号公報の高圧燃料噴射管ではその強度が不
足する事態も考慮しなければならなくなってきた。[0003] The high-pressure fuel injection pipe described in this publication has an injection time of 1 to 1 as a measure against NOx reduction and black smoke.
2 msec, flow rate up to 50 m / sec, internal pressure 600 ~
Even when operating under the conditions corresponding to the current high injection pressure of fuel of 1000 bar (peak pressure), not only cavitation erosion (hereinafter simply referred to as erosion) on the inner peripheral surface can be prevented, but also repeated high pressure fatigue. The durability of the film was almost satisfactory. However, in recent years, the conditions for NOx reduction and black smoke countermeasures have become more severe, and there has been a tendency to require a high-pressure fuel injection pipe that does not repeatedly break down due to high-pressure fatigue even under severe injection conditions in which the internal pressure exceeds 1200 bar.
In the high-pressure fuel injection pipe disclosed in Japanese Patent No. 46712, it is necessary to consider a situation where the strength is insufficient.
【０００４】[0004]
【発明が解決しようとする課題】このような過酷な噴射
条件でも内圧繰返し疲労強度を有する高圧燃料噴射管
を、本出願人は特開平２−２４７０８５号公報により提
案した。この公報による高圧燃料噴射管は、内管の内周
壁にＮｉ、Ｃｒ、Ｍｏ、Ｃｏ、Ａｌ、Ｃｕから選ばれた
少なくとも１種またはこれら基合金の拡散層を有するた
め、該内管の硬度が高くエロージョンの防止の観点から
は好ましいものであった。しかしながら特開平２−２４
７０８５号公報の技術はその製造工程において次の点で
問題があった。すなわち内管側はエロージョンの発生の
防止のために十分な硬度の拡散層を有しているが、二重
金属管を形成するために外管に内管を内挿して重合さ
せ、伸管加工した後に加熱して拡散させるので、外管は
該加熱によって焼きなまし状態となり、したがって伸管
加工後に熱処理をしないか、あるいは焼鈍程度の熱処理
しかしない従来技術の二重金属管の外管に比べて硬度が
低く、曲げ振動疲労強度の一層の向上が求められてい
た。The applicant of the present invention has proposed a high-pressure fuel injection pipe having an internal pressure repetitive fatigue strength even under such severe injection conditions, as disclosed in Japanese Patent Application Laid-Open No. 2-247085. The high-pressure fuel injection pipe according to this publication has a diffusion layer of at least one selected from Ni, Cr, Mo, Co, Al, and Cu or a base alloy thereof on the inner peripheral wall of the inner pipe. It was highly preferable from the viewpoint of prevention of erosion. However, Japanese Patent Laid-Open No. 2-24
The technique disclosed in Japanese Patent No. 7085 has the following problems in the manufacturing process. That is, although the inner tube side has a diffusion layer of sufficient hardness to prevent the occurrence of erosion, the inner tube is inserted into the outer tube to form a double metal tube, polymerized, and drawn. Since the outer tube is heated and diffused later, the outer tube is in an annealed state by the heating, and therefore has a lower hardness than the outer tube of the prior art double metal tube which is not heat-treated after the drawing process or only heat-treated to the extent of annealing. Further, further improvement in bending vibration fatigue strength has been required.
【０００５】したがって本発明は、上記燃料噴射条件よ
り過酷な管内ピーク圧が１２００ｂａｒを超えかつ負圧
を含みキャビテーションが発生する特殊な噴射条件の下
でも前記公報において問題となった内圧繰返し疲労強度
や曲げ振動疲労強度を向上するとともに、その内周面に
おいて十分な耐エロージョン性能を発揮し得る高圧燃料
噴射管の製造方法および高圧燃料噴射管を提供すること
を目的とするものである。[0005] Accordingly, the present invention provides an internal pressure repetitive fatigue strength, which is a problem in the above-mentioned publication, even under a special injection condition in which the pipe peak pressure, which is more severe than the above fuel injection condition, exceeds 1200 bar and includes cavitation including negative pressure. It is an object of the present invention to provide a method for manufacturing a high-pressure fuel injection pipe and a high-pressure fuel injection pipe capable of improving bending vibration fatigue strength and exhibiting sufficient erosion resistance on the inner peripheral surface thereof.
【０００６】[0006]
【課題を解決するための手段】本発明者は、厚肉の鋼管
からなる外管と、該外管に圧嵌された硬質の薄肉の鋼管
からなる内管とから構成された二重金属管による高圧燃
料噴射管において、内周面側にガス窒化法、塩浴窒化法
あるいはイオン窒化法などによる窒化処理を施して形成
された窒化層を有する内管を外管に内挿し、空引きによ
る伸管加工によって外管のみ、もしくは外管とともに内
管を僅かに縮径して前記外管の内周面を前記内管の外周
面に少なくとも密着せしめることにより内圧繰返し疲労
強度と曲げ振動疲労強度をともに向上できることを見出
し本発明を完成するに至った。SUMMARY OF THE INVENTION The present inventor has proposed a double metal pipe composed of an outer pipe made of a thick steel pipe and an inner pipe made of a hard thin steel pipe pressed into the outer pipe. In a high-pressure fuel injection pipe, an inner pipe having a nitride layer formed by performing a nitriding treatment on the inner peripheral surface side by a gas nitriding method, a salt bath nitriding method, an ion nitriding method, or the like is inserted into the outer pipe, and drawn by vacuum. Only the outer pipe or the inner pipe together with the outer pipe is slightly reduced in diameter by pipe processing so that the inner peripheral surface of the outer pipe is at least in close contact with the outer peripheral surface of the inner pipe to reduce the internal pressure repeated fatigue strength and bending vibration fatigue strength. They have found that both can be improved, and have completed the present invention.
【０００７】すなわち上記目的を達成するため本発明の
第１の第１の実施態様は、厚肉の鋼管からなる外管に、
該外管より硬質の薄肉の鋼管からなる内管を内挿せしめ
伸管加工を実施して二重金属管を形成する方法におい
て、前記内管を製品寸法まで芯引きによる伸管加工によ
って縮径し、ついで該内管の内周面側に窒化処理を施
し、その後このようにして内周面側に窒化層を形成され
た内管を外管内に内挿し、空引きによる伸管加工によっ
て前記外管のみを縮径せしめ該外管の内周面を前記内管
の外周面に少なくとも密着せしめた高圧燃料噴射管の製
造方法を特徴とし、また前記窒化処理はガス窒化法、塩
浴窒化法あるいはイオン窒化法により実施し、さらに前
記窒化層の硬度（Ｈｖ）を８００以下としたものであ
る。[0007] That is, in order to achieve the above object, a first embodiment of the present invention provides an outer pipe made of a thick steel pipe,
In a method of forming a double metal pipe by inserting an inner pipe made of a thin steel pipe harder than the outer pipe to form a double metal pipe, the inner pipe is reduced in diameter by core drawing to a product size. Then, a nitriding treatment is performed on the inner peripheral surface side of the inner tube, and then the inner tube having the nitrided layer formed on the inner peripheral surface side is inserted into the outer tube, and the outer tube is drawn by drawing to form the outer tube. The method is characterized by a method of manufacturing a high-pressure fuel injection pipe in which only the pipe is reduced in diameter and the inner peripheral surface of the outer pipe is at least brought into close contact with the outer peripheral face of the inner pipe, and the nitriding treatment is a gas nitriding method, a salt bath nitriding method or It is performed by an ion nitriding method, and the hardness (Hv) of the nitrided layer is 800 or less.
【０００８】また本発明の第２の実施態様は、厚肉の鋼
管からなる外管に、該外管より硬質の薄肉の鋼管からな
る内管を内挿せしめ伸管加工を実施して二重金属管を形
成する方法において、前記内管をほぼ製品寸法まで芯引
きによる伸管加工によって縮径し、ついで該内管の内周
面側に窒化処理を施し、その後このようにして内周面側
に窒化層を形成された内管を外管内に内挿し、空引きに
よる伸管加工によって前記外管を縮径せしめるととも
に、前記内管を僅かに縮径して前記外管の内周面を該内
管の外周面に少なくとも密着せしめた高圧燃料噴射管の
製造方法を特徴とし、また前記内管を、断面減少率（リ
ダクション）が１０％以下となるよう縮径し、前記窒化
処理はガス窒化法、塩浴窒化法あるいはイオン窒化法に
より実施することが好ましい。さらに前記窒化層の硬度
（Ｈｖ）を８００以下としたものである。[0008] In a second embodiment of the present invention, an inner pipe made of a thin steel pipe harder than the outer pipe is inserted into an outer pipe made of a thicker steel pipe, and a drawing process is performed by performing drawing. In the method of forming a pipe, the inner pipe is reduced in diameter to a product size by core drawing, and then nitriding is performed on the inner peripheral side of the inner pipe. The inner pipe having a nitrided layer formed therein is inserted into the outer pipe, and the outer pipe is reduced in diameter by drawing by drawing, and the inner pipe is slightly reduced in diameter to reduce the inner peripheral surface of the outer pipe. The method is characterized by a method of manufacturing a high-pressure fuel injection pipe that is at least in close contact with the outer peripheral surface of the inner pipe. The inner pipe is reduced in diameter so that a cross-sectional reduction rate (reduction) is 10% or less. It can be carried out by nitriding, salt bath nitriding or ion nitriding. Masui. Further, the hardness (Hv) of the nitrided layer is 800 or less.
【０００９】さらに本発明の第３の実施態様は、厚肉の
鋼管からなる外管に、該外管より硬質の薄肉の鋼管から
なる内管を嵌合して形成した二重金属管において、空引
きによる伸管加工によって縮径された外管の内周面が少
なくとも密着してなる前記内管の内周面側に窒化層を有
してなる高圧燃料噴射管を特徴とし、また前記窒化層は
硬度（Ｈｖ）が８００以下であることが好ましい。Further, a third embodiment of the present invention relates to a double metal pipe formed by fitting an inner pipe made of a thin steel pipe harder than the outer pipe to an outer pipe made of a thicker steel pipe. A high-pressure fuel injection pipe having a nitrided layer on the inner peripheral surface side of the inner pipe in which the inner peripheral surface of the outer pipe reduced in diameter by drawing by pipe drawing is at least in close contact with each other; Preferably has a hardness (Hv) of 800 or less.
【００１０】[0010]
【発明の実施の形態】以下、本発明を添付図面に基づい
て説明すれば、図１は本発明の高圧燃料噴射管の一実施
例を示す正面図、図２は本発明のその製造方法を示す図
で、（ａ）は内管の伸管加工を示す部分概略説明図、
（ｂ）は内管と外管を重合する伸管加工を示す部分概略
説明図、図３は本発明の高圧燃料噴射管と従来の高圧燃
料噴射管との曲げ振動疲労強度とを示すため曲げ破壊ま
での振動サイクルと繰返し応力との関係を示すグラフ図
であって、１は管径２０ｍｍ以下の比較的厚肉で細径の
内径を有する高圧配管用炭素鋼鋼管で、例えばＳＴＳ
３７０、４１０、４８０、あるいはＤＩＮ Ｓｔ ５２
などの炭素鋼や合金鋼などから形成された単層または多
重巻管からなる外管である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view showing an embodiment of a high-pressure fuel injection pipe according to the present invention; FIG. (A) is a partial schematic explanatory view showing an elongation process of an inner tube,
(B) is a partial schematic explanatory view showing a drawing process of superimposing an inner tube and an outer tube, and FIG. 3 is a diagram showing bending vibration fatigue strength of a high-pressure fuel injection tube of the present invention and a conventional high-pressure fuel injection tube. It is a graph which shows the relationship between the vibration cycle until fracture and the repetitive stress, wherein 1 is a carbon steel pipe for high-pressure piping having a relatively thick wall having a diameter of 20 mm or less and a small diameter, for example, STS.
370, 410, 480 or DIN St 52
It is an outer tube composed of a single-layer or multi-turn tube made of carbon steel, alloy steel, or the like.
【００１１】また２は前記外管１の内側に位置するよう
密着ないし僅かに圧接されて内部に流通路を形成する該
外管より硬質の、例えばＳＵＳ ３０１、ＳＵＳ ３０
４などのような主としてオーステナイト系ステンレス鋼
管などから形成されたものである。そして前記内管２の
内周面側にガス窒化法、塩浴窒化法あるいはイオン窒化
法などのような窒化処理を施して、層厚２０〜１００μ
ｍ程度の窒化層３を形成する。そして窒化層３の形成の
ためにガス窒化法を使用する場合、内管の両端にそれぞ
れ導管を接続し、ガス源からのアンモニアガスを前記内
管内に流通させ、ついで内管を約５００℃程度で加熱し
て流通するアンモニアガスを分解し、その反応によって
内管の内周面で生じた発生期の窒素を拡散させ、合金元
素の窒化物を形成させるものである。Reference numeral 2 denotes a harder member, for example, SUS 301, SUS 30 than the outer tube, which is located inside the outer tube 1 and is closely or slightly pressed to form a flow passage therein.
4, mainly made of an austenitic stainless steel pipe. A nitriding treatment such as a gas nitriding method, a salt bath nitriding method, or an ion nitriding method is performed on the inner peripheral surface side of the inner pipe 2 to have a layer thickness of 20 to 100 μm.
A nitride layer 3 of about m is formed. When the gas nitriding method is used for forming the nitrided layer 3, conduits are connected to both ends of the inner tube, ammonia gas from a gas source flows through the inner tube, and then the inner tube is heated to about 500 ° C. Is heated to decompose the flowing ammonia gas, diffuse the nascent nitrogen generated on the inner peripheral surface of the inner tube by the reaction, and form a nitride of an alloy element.
【００１２】また塩浴窒化法を使用する場合、ガス窒化
法と同様に内管内にシアン化カリ（ＫＣＮ）あるいはシ
アン化ナトリウム（ＮａＣＮ）の溶融塩を流通させ、窒
素を浸透させるものである。しかしシアン化カリ（ＫＣ
Ｎ）とシアン化ナトリウム（ＮａＣＮ）は猛毒であるた
め管理が難しく、窒化力は劣るもののこれらの青酸塩に
空気を吹込んで酸化させＫＣＮＯおよびＮａＣＮＯにし
て毒性を弱めて窒化する、いわゆる軟窒化法を用いるこ
ともできる。なお軟窒化法は通常の塩浴窒化法に比べて
窒化層の密着性がよく、疲労強度が向上するという利点
があるため本発明を実施するには好ましい方法である。When the salt bath nitriding method is used, similarly to the gas nitriding method, a molten salt of potassium cyanide (KCN) or sodium cyanide (NaCN) is circulated in the inner tube to permeate nitrogen. However, potassium cyanide (KC
N) and sodium cyanide (NaCN) are so toxic that their management is difficult and their nitriding power is inferior. Can also be used. The nitrocarburizing method is a preferable method for implementing the present invention because it has the advantages that the adhesion of the nitrided layer is better and the fatigue strength is improved as compared with the ordinary salt bath nitriding method.
【００１３】つぎにイオン窒化法を使用する場合、１０
−２〜１０−３Ｐａの低圧のＮ２＋Ｈ２混合ガス中に内
管を設置し、内管を陰極にし棒状陽極を内管内に挿入し
てその間に数百ボルトの直流電圧を印加し、グロー放電
を発生させイオン化されたＮ＋、ＮＨ＋を加速させて内
管内周面に衝突させ窒化するものである。Next, when the ion nitriding method is used, 10
An inner tube is installed in a low-pressure N 2 + H 2 mixed gas of −2 to 10 −3 Pa, a rod-shaped anode is inserted into the inner tube while the inner tube is used as a cathode, and a DC voltage of several hundred volts is applied between them, A glow discharge is generated to accelerate the ionized N + and NH + and cause them to collide with the inner peripheral surface of the inner tube to be nitrided.
【００１４】このようにして得られた内管２の内周面側
の窒化層３の硬度（Ｈｖ）は、処理時間や内管の材質な
どによって異なるが、通常硬度（Ｈｖ）８００以下、好
ましくは（Ｈｖ）４００〜６５０とすることが必要で、
硬度（Ｈｖ）が８００を超えると硬度が高過ぎて接続頭
部成形や曲げ加工時にこの窒化層に亀裂や剥離が発生す
る可能性が大であるからである。なお硬度（Ｈｖ）４０
０未満では管内ピーク圧が１２００ｂａｒを超えかつ負
圧を含みキャビテーションが発生する特殊な噴射条件の
超高圧燃料に対する耐エロージョン性能が十分でない場
合があるため、硬度（Ｈｖ）の下限は４００以上とする
ことが好ましい。The hardness (Hv) of the nitrided layer 3 on the inner peripheral surface side of the inner tube 2 thus obtained varies depending on the processing time, the material of the inner tube, and the like. Needs to be (Hv) 400-650,
If the hardness (Hv) exceeds 800, the hardness is too high and there is a high possibility that cracks or peeling will occur in this nitrided layer during connection head forming or bending. Hardness (Hv) 40
If the pressure is less than 0, the peak pressure in the pipe exceeds 1200 bar and the erosion resistance to an ultra-high pressure fuel under special injection conditions including negative pressure and cavitation may not be sufficient. Therefore, the lower limit of the hardness (Hv) is 400 or more. Is preferred.
【００１５】そして外管１に、前記のようにして内周面
側に窒化層３が形成された内管２を内挿した後、伸管加
工によって外管１のみ、もしくは外管１とともに内管２
を僅かに縮径して前記外管１の内周面を前記内管２の外
周面に密着ないし僅かに圧接せしめることにより二重金
属管からなる噴射管材を形成する。この際、形成された
二重金属管の外径に対する内管２の肉厚の割合は、前記
特公平１−４６７１２号公報記載と同様に１．２〜８．
５％が好ましいが、内管の肉厚をこの割合より厚くする
こともできる。After the inner tube 2 having the nitrided layer 3 formed on the inner peripheral surface side is inserted into the outer tube 1 as described above, only the outer tube 1 or the inner tube together with the outer tube 1 is formed by drawing. Tube 2
Is slightly reduced in diameter, and the inner peripheral surface of the outer tube 1 is closely or slightly pressed against the outer peripheral surface of the inner tube 2 to form an injection tube made of a double metal tube. At this time, the ratio of the wall thickness of the inner tube 2 to the outer diameter of the formed double metal tube is 1.2 to 8 in the same manner as described in JP-B 1-46712.
Although 5% is preferable, the thickness of the inner tube can be made larger than this ratio.
【００１６】つぎに上記のように構成される二重金属管
からなる高圧燃料噴射管の製造方法を図２に基づいて説
明する。まず図２（ａ）に図示するように内管２は予め
プラグ６とダイス７を用いて２〜４回芯引きによる伸管
加工によって製品寸法の肉厚またはほぼ製品寸法に近い
肉厚まで縮径され、該芯引きによる伸管加工により加工
硬化する。Next, a method of manufacturing a high-pressure fuel injection pipe composed of a double metal pipe configured as described above will be described with reference to FIG. First, as shown in FIG. 2 (a), the inner tube 2 is reduced to a wall thickness of a product size or a wall thickness almost close to the product size by a drawing process using a plug 6 and a die 7 by core drawing two to four times in advance. Worked and hardened by pipe drawing by the core drawing.
【００１７】つぎに、製品寸法の肉厚またはほぼ製品寸
法に近い肉厚まで縮径された内管２の内周面側に前記し
たようにガス窒化法、塩浴窒化法あるいはイオン窒化法
などのような窒化処理を施して所定層厚の窒化層３を形
成する。Next, as described above, a gas nitriding method, a salt bath nitriding method, an ion nitriding method, or the like is provided on the inner peripheral surface side of the inner pipe 2 whose diameter is reduced to a thickness of the product size or a thickness substantially close to the product size. Is performed to form the nitrided layer 3 having a predetermined thickness.
【００１８】つぎに上記のようにして芯引きにより伸管
加工され、かつ内周面側に窒化層３を形成された内管２
を外管１内に間隙をおいて内挿し、図２（ｂ）に示すよ
うにダイス８を用いて少なくとも１回空引きによる伸管
加工することにより該外管１を縮径し、内挿した内管２
の外周面にその内周面を密着ないし僅かに圧接する。こ
の際内管２は図２（ｂ）のように前記した製品寸法の肉
厚のまま、もしくは外管１の縮径とともに僅かに縮径す
るよう伸管加工される必要がある。その理由は前工程に
おいて内管２の内周面側に形成された窒化層３が当該内
管２の伸管加工による縮径によって亀裂や剥離などの発
生のないようにするためであって、製品寸法の肉厚のま
まであれば当然前記窒化層の亀裂や剥離などの発生を防
止できるが、本発明者は１０％以下、好ましくは５％以
下の僅かな縮径であれば前記亀裂や剥離などの発生を防
止できることを見出した。Next, as described above, the inner tube 2 is drawn by core drawing and has a nitrided layer 3 formed on the inner peripheral surface side.
Is inserted into the outer tube 1 with a gap therebetween, and the outer tube 1 is reduced in diameter by drawing at least once by using a die 8 as shown in FIG. Tauchi pipe 2
The inner peripheral surface is closely contacted or slightly pressed against the outer peripheral surface. At this time, the inner pipe 2 needs to be stretched so as to have a wall thickness of the above-mentioned product size as shown in FIG. The reason for this is to prevent the nitride layer 3 formed on the inner peripheral surface side of the inner tube 2 in the previous step from generating cracks or peeling due to the diameter reduction by the drawing process of the inner tube 2, If the thickness of the product remains the same, the occurrence of cracks or peeling of the nitrided layer can be naturally prevented. However, the present inventor has found that if the diameter is slightly reduced to 10% or less, preferably 5% or less, the cracks or It has been found that peeling and the like can be prevented.
【００１９】すなわち外管１とともに内管２をダイスを
用いて空引きにより伸管加工をする際に、内管２の断面
減少率（リダクション）が１０％を超えると内管２の内
周面側に形成された窒化層３に亀裂や剥離などの現象の
発生が顕著となり、結果として前記した１０００ｂａｒ
を超えるような過酷な噴射条件下では繰返し高圧疲労に
よる破壊の発生率が急上昇するとともに、窒化層３の剥
落により該窒化層３の剥落片が噴射ノズルなどに詰まり
エンジン不調の発生が急激に上昇することが分かった。
したがって内管２は伸管加工の際に縮径しないことが好
ましいが、その断面減少率を１０％以下、好ましくは５
％以下にすることにより前記した窒化層の亀裂や剥離な
どの問題が発生せず、これにより繰返し高圧疲労による
破壊の発生率を大幅に減少させ、かつエンジン不調の原
因を大幅に取除くことができる。なお空引きによる伸管
加工の際には、内管２の内周面が塑性変形しない程度に
外管１の内周面により内管２の外周面を圧縮するもので
ある。That is, when the inner pipe 2 is drawn together with the outer pipe 1 by drawing using a die, if the cross-sectional reduction rate (reduction) of the inner pipe 2 exceeds 10%, the inner peripheral surface of the inner pipe 2 is reduced. Phenomena such as cracks and peeling occur remarkably in the nitride layer 3 formed on the side, and as a result, the above-mentioned 1000 bar
Under severe injection conditions, the rate of breakage due to repeated high-pressure fatigue rises sharply, and splinters of the nitrided layer 3 cause the splinters of the nitrided layer 3 to clog the injection nozzles and the like, causing a sudden increase in engine malfunction. I found out.
Therefore, the inner pipe 2 is preferably not reduced in diameter during the drawing process, but the cross-sectional reduction rate is 10% or less, preferably 5%.
% Or less, the above-mentioned problems such as cracking and peeling of the nitrided layer do not occur, thereby greatly reducing the rate of occurrence of breakage due to repeated high-pressure fatigue, and greatly eliminating the cause of engine malfunction. it can. In the case of drawing by the drawing, the outer peripheral surface of the inner tube 2 is compressed by the inner peripheral surface of the outer tube 1 so that the inner peripheral surface of the inner tube 2 is not plastically deformed.
【００２０】上記のように形成された二重金属管からな
る高圧燃料噴射管は、ついで公知のように割型チャック
によりチャックされてパンチ部材を用いてプレス加工に
より接続端部に截頭円錐状、円弧状または算盤珠状の接
続頭部が成形されるか、あるいは接続頭部成形なしに内
周にねじを設けたフランジやスリーブを取付けるために
その外周にねじ加工し、ナットとともにフランジやスリ
ーブをねじ込み、通常その後にディーゼル内燃機関に配
管するために曲げ加工が施される。The high-pressure fuel injection pipe formed of the double metal pipe formed as described above is then chucked by a split chuck as is well known, and is pressed into a frustoconical shape at the connection end by using a punch member. An arc-shaped or abacus-shaped connection head is formed, or the connection head is threaded on the outer periphery to mount a flange or sleeve with a thread on the inside without forming the connection head, and the flange or sleeve is attached together with the nut. Screwing, usually followed by bending for piping to a diesel internal combustion engine.
【００２１】[0021]
【実施例】つぎに本発明の実施例を比較例とともに以下
に説明する。 実施例１ 清浄化のための前処理を施して長さ２０００ｍｍに切断
したＳＵＳ ３０１からなるステンレス鋼管の内管を３
回の芯引きによる伸管加工によって、外径３．５ｍｍ、
内径２．５ｍｍ、肉厚０．５ｍｍに縮径した。ついで、
該内管内にアンモニアガスを流通させるとともに該内管
を約４５０℃で加熱し、内管の内周面側に層厚１００μ
ｍの窒化層を形成した。この際該窒化層の硬度（Ｈｖ）
は７００であった。ついで清浄化のための前処理を施し
た長さ２０００ｍｍのＳＴＳ ３７０からなる鋼管の外
管（外径１２ｍｍ、内径７．２ｍｍ、肉厚２．４ｍｍ）
の内部に前記内管を緩やかに内挿せしめた。その後固定
したダイスを用いて空引きによる伸管加工を１回行って
外管側を縮径せしめ、ついで矯正加工して外径８．０ｍ
ｍ、内径２．５ｍｍ、肉厚２．７５ｍｍの二重金属管か
らなる噴射管材を得、しかる後に３００ｍｍの長さに切
断した試料を２０本準備した。Next, examples of the present invention will be described below together with comparative examples. Example 1 An inner stainless steel pipe made of SUS 301 cut to a length of 2000 mm after being subjected to a pretreatment for cleaning, and having a length of 3 mm.
The outer diameter is 3.5mm,
The inner diameter was reduced to 2.5 mm and the wall thickness was reduced to 0.5 mm. Then
Ammonia gas is allowed to flow through the inner tube, and the inner tube is heated at about 450 ° C. to a thickness of 100 μm on the inner peripheral surface side of the inner tube.
m was formed. At this time, the hardness (Hv) of the nitrided layer
Was 700. Then, an outer tube (outer diameter 12 mm, inner diameter 7.2 mm, wall thickness 2.4 mm) made of STS 370 having a length of 2000 mm and subjected to pretreatment for cleaning.
The inner tube was gently inserted inside the tube. Thereafter, using a fixed die, drawing was performed once by vacuuming to reduce the outer tube side, and then straightening was performed to obtain an outer diameter of 8.0 m.
An injection tube made of a double metal tube having a diameter of 2.5 mm, an inner diameter of 2.5 mm, and a thickness of 2.75 mm was obtained, and then 20 samples cut to a length of 300 mm were prepared.
【００２２】このように準備した２０本の二重金属管か
らなる噴射管材を、ディーゼル機関用燃料噴射ポンプお
よびインジェクターを使用して、該ポンプとインジェク
ターの間に配設し、燃料噴射ポンプを駆動して内圧１２
００ｂａｒ（ピーク圧）の噴射条件で内圧繰返し疲労強
度試験を行なった。このように準備した２０本の二重金
属管からなる噴射管材を、ディーゼル機関用燃料噴射ポ
ンプおよびインジェクターを使用して、該ポンプとイン
ジェクターの間に配設し、燃料噴射ポンプを駆動してキ
ャビテーションの発生する管内のピーク圧が１２００ｂ
ａｒでかつ負圧を含む噴射条件でキャビテーション試験
を２００時間行なった。その結果得られた全ての試料に
ついて試験終了後にエロージョンの発生は見られなかっ
た。また管内のピーク圧が１２００ｂａｒでかつ負圧を
含まない噴射条件で内圧繰返し疲労強度試験を１０７回
実施したが、破壊には至らなかった。さらにＪＡＳＯ
Ｍ １０４−６６に準じた曲げ振動疲労強度試験を行っ
たが、疲労限は約２３０ＰＭａであり、図３の実線に示
すような曲げ振動疲労強度を有することが分かった。The injection pipe made of 20 double metal pipes prepared as described above is disposed between the diesel engine fuel injection pump and injector using a fuel injection pump and an injector, and the fuel injection pump is driven. Internal pressure 12
The internal pressure repeated fatigue strength test was performed under the injection condition of 00 bar (peak pressure). The injection pipe made of 20 double metal pipes prepared in this way is disposed between the diesel engine fuel injection pump and the injector using a fuel injection pump and the injector, and the fuel injection pump is driven to drive cavitation. The peak pressure in the generated pipe is 1200b
The cavitation test was performed for 200 hours under ar and injection conditions including negative pressure. No erosion was observed after the test for all the samples obtained. The peak pressure in the tube was performed internal pressure cyclic fatigue strength test 107 times the injection free conditions a and negative pressure 1200bar, but did not result in destruction. Furthermore, JASO
A bending vibration fatigue strength test according to M104-66 was performed, and it was found that the fatigue limit was about 230 PMa and the bending vibration fatigue strength was as indicated by the solid line in FIG.
【００２３】実施例２ 内管として実施例１と同一寸法で同一材質のステンレス
鋼管を３回の芯引きして伸管加工により縮径した後、内
管内にシアン化ナトリウムの溶融塩に空気を吹込んで酸
化させたＮａＣＮＯを流通させて内管の内周面に窒化処
理を施し、層厚５００μｍの窒化層を形成した。この際
該窒化層の硬度（Ｈｖ）は６５０であった。ついで実施
例１と同様の寸法と材質の外管内部に前記内管を緩やか
に内挿せしめて外管とともに内管を僅かに縮径するよう
ダイスを用いて空引きにより伸管加工を行い、その後矯
正加工して外径８．０ｍｍ、内径２．４ｍｍ、肉厚２．
８ｍｍ（断面減少率：約３％）の二重金属管からなる噴
射管材を得、しかる後に３００ｍｍの長さに切断した試
料を２０本準備した。Example 2 A stainless steel tube of the same material and the same material as in Example 1 was drawn three times as the inner tube and reduced in diameter by drawing, and then air was introduced into the inner tube into the molten salt of sodium cyanide. The inner peripheral surface of the inner tube was subjected to a nitriding treatment by flowing the blown and oxidized NaCNO to form a nitrided layer having a thickness of 500 μm. At this time, the hardness (Hv) of the nitrided layer was 650. Then, the inner pipe is gently inserted into the outer pipe having the same dimensions and material as in Example 1, and the pipe is drawn by vacuum using a die to slightly reduce the diameter of the inner pipe together with the outer pipe. After straightening, the outer diameter is 8.0 mm, the inner diameter is 2.4 mm, and the wall thickness is 2.
An injection tube made of a double metal tube of 8 mm (cross-section reduction rate: about 3%) was obtained, and then 20 samples cut to a length of 300 mm were prepared.
【００２４】このように準備した２０本の二重金属管か
らなる噴射管材について実施例１と同様のキャビテーシ
ョン試験と内圧繰返し疲労強度試験を行った結果、得ら
れた全ての試料について試験終了後にエロージョンの発
生は見られず、また１０７回の圧力繰返し終了まで破壊
には至らなかった。さらに曲げ振動疲労強度試験の結果
も図３の実線に示すように大幅に向上した。A cavitation test and an internal pressure repeated fatigue test similar to those in Example 1 were performed on the injection pipe made of 20 double metal pipes prepared as described above. As a result, all the samples obtained were subjected to erosion after the test was completed. occurrence was not observed, also did not lead to destruction up to 10 7 times of pressure repeat end. Further, the result of the bending vibration fatigue strength test was greatly improved as shown by the solid line in FIG.
【００２５】比較例１ それぞれ清浄化のための前処理を施して長さ２０００ｍ
ｍに切断したＳＵＳ３０１からなる鋼管からなるステン
レス鋼管の内管を３回の芯引きによる伸管加工によっ
て、外径４．８ｍｍ、内径３．８ｍｍ、肉厚０．５ｍｍ
になるよう縮径し、ついで清浄化のための前処理を施し
た長さ２０００ｍｍのＳＴＳ ３７０の鋼管からなる外
管（外径１２ｍｍ、内径６．９ｍｍ、肉厚２．５５ｍ
ｍ）の内部に前記内管を緩やかに内挿せしめた。その後
固定したダイスを用いて前記内外管を圧嵌するよう両管
を同時に、かつ一体的に空引きによる伸管加工を１回行
って縮径せしめ、ついで矯正加工して外径８．０ｍｍ、
内径２．５ｍｍ、肉厚２．７５ｍｍ（断面減少率：約３
０％）の二重金属管からなる噴射管材を得、しかる後に
３００ｍｍの長さに切断した試料を２０本準備した。な
お得られた試料における内管の硬度（Ｈｖ）は４９０で
あった。Comparative Example 1 Each of which was subjected to a pretreatment for cleaning to a length of 2000 m.
4.8 mm outer diameter, 3.8 mm inner diameter, 0.5 mm wall thickness by drawing the inner pipe of stainless steel pipe made of SUS301 made of SUS301 into three pipes by centering three times
An outer tube (outer diameter 12 mm, inner diameter 6.9 mm, wall thickness 2.55 m) made of a STS 370 steel pipe having a length of 2000 mm and a pretreatment for cleaning and having a reduced diameter.
The inner tube was gently inserted inside m). Then, the inner and outer pipes were pressed simultaneously using a fixed die, and the pipes were simultaneously and integrally subjected to a single drawing operation to reduce the diameter, and then straightened to form an outer diameter of 8.0 mm.
Inner diameter 2.5 mm, wall thickness 2.75 mm (section reduction rate: about 3
(0%) of a double metal tube, and thereafter, 20 samples cut to a length of 300 mm were prepared. The hardness (Hv) of the inner tube in the obtained sample was 490.
【００２６】このように準備した２０本の二重金属管か
らなる噴射管材について、実施例１と同様にして２００
時間のキャビテーション試験を行なった結果、エロージ
ョンの発生したものが見られた。また実施例１と同様に
して内圧繰返し疲労強度試験を行ったが内管に破壊に至
るものが見られた。さらにＪＡＳＯ Ｍ １０４−６６
に準じた曲げ振動疲労強度試験を行ったが、疲労限は約
１７０ＰＭａであり、図３の一点鎖線に示すように曲げ
振動疲労強度が劣っていることが分かった。In the same manner as in the first embodiment, the injection pipe made of 20 double metal pipes thus prepared
As a result of a time cavitation test, erosion was observed. An internal pressure repeated fatigue strength test was carried out in the same manner as in Example 1, but it was found that the inner pipe was broken. In addition, JASO M 104-66
A bending vibration fatigue strength test was carried out according to the above, and it was found that the fatigue limit was about 170 PMa, and the bending vibration fatigue strength was inferior as shown by the dashed line in FIG.
【００２７】比較例２ 比較例１と同様の寸法と材質の内管と外管を用いて、比
較例１と同様に両管を同時に、かつ一体的に空引きによ
る伸管加工を１回行って縮径せしめ、ついで矯正加工し
て噴射管材を得、しかる後に３００ｍｍの長さに切断し
た試料を２０本準備した。ただし内径は２．４ｍｍ（断
面減少率：約３２％）とした。Comparative Example 2 Using the inner tube and the outer tube having the same dimensions and materials as in Comparative Example 1, both tubes were simultaneously and integrally subjected to a single drawing operation by vacuum drawing, as in Comparative Example 1. The diameter was reduced and then straightened to obtain an injection tube material. Thereafter, 20 samples cut to a length of 300 mm were prepared. However, the inner diameter was 2.4 mm (cross-sectional reduction rate: about 32%).
【００２８】このように準備した２０本の二重金属管か
らなる噴射管材について、実施例１と同様にして２００
時間のキャビテーション試験を行なった結果、エロージ
ョンの発生したものが見られた。また実施例１と同様に
して内圧繰返し疲労強度試験を行ったが内管に破壊に至
るものが見られた。さらに曲げ振動疲労強度試験の結果
も図３の一点鎖線に示すように劣っていることが分かっ
た。In the same manner as in the first embodiment, the injection pipe made of 20 double metal pipes thus prepared
As a result of a time cavitation test, erosion was observed. An internal pressure repeated fatigue strength test was carried out in the same manner as in Example 1, but it was found that the inner pipe was broken. Further, it was also found that the results of the bending vibration fatigue strength test were inferior as shown by the dashed line in FIG.
【００２９】実施例３ 内管として実施例１と同一の寸法であるがＳＵＳ ３０
４からなるステンレス鋼管を３回の芯引きして伸管加工
により縮径した後、この内管を１０−２〜１０−３Ｐａ
の低圧のＮ２＋Ｈ２混合ガス中に設置し、直流電源に該
内管を陰極とし、また棒状電極を陽極として接続して該
陰極と陽極の間に５００ボルト直流電圧を印加し、グロ
ー放電を発生させイオン化されたＮ＋、ＮＨ＋により内
管の内周面側に層厚２００μｍの窒化層を形成した。こ
の際該窒化層の表面硬度（Ｈｖ）は８００であった。一
方実施例１と同様の寸法であるがＳＴＳ ４１０の鋼管
からなる外管の内部に前記内管を緩やかに内挿せしめ
た。その後固定したダイスを用いて空引きによる伸管加
工を１回行って外管側を縮径せしめ、ついで矯正加工し
て外径８．０ｍｍ、内径２．５ｍｍ、肉厚２．７５ｍｍ
の二重金属管からなる噴射管材を得、しかる後に３００
ｍｍの長さに切断した試料を２０本準備した。Example 3 The inner tube has the same dimensions as in Example 1 but is made of SUS 30.
After the stainless steel tube made of No. 4 was drawn three times and reduced in diameter by drawing, the inner tube was cooled to 10 −2 to 10 −3 Pa.
Is connected to a low-pressure N 2 + H 2 mixed gas, and the inner tube is used as a cathode and a rod-shaped electrode is connected as an anode to a DC power supply, and a 500 volt DC voltage is applied between the cathode and the anode to perform glow discharge. Was generated and a nitride layer having a thickness of 200 μm was formed on the inner peripheral surface side of the inner tube with ionized N + and NH + . At this time, the surface hardness (Hv) of the nitrided layer was 800. On the other hand, the inner pipe was gently inserted into the outer pipe made of the STS410 steel pipe having the same dimensions as in Example 1. Thereafter, the outer tube side is reduced by performing drawing once by vacuuming using a fixed die to reduce the outer tube side. Then, the outer tube is subjected to a correction process to have an outer diameter of 8.0 mm, an inner diameter of 2.5 mm, and a wall thickness of 2.75 mm.
Injection tube consisting of a double metal tube of
20 samples cut to the length of mm were prepared.
【００３０】このように準備した２０本の二重金属管か
らなる噴射管材について実施例１と同様のキャビテーシ
ョン試験と内圧繰返し疲労強度試験を行った結果、得ら
れた全ての試料試料について試験終了後にエロージョン
の発生は見られず、また１０７回の圧力繰返し終了まで
破壊には至らなかった。さらに曲げ振動疲労強度試験の
結果も図３の実線に示すように大幅に向上した。A cavitation test and an internal pressure repeated fatigue test similar to those in Example 1 were performed on the injection pipe made of the 20 double metal pipes prepared as described above. As a result, all of the obtained samples were subjected to erosion after the test was completed. of occurrence was not observed, also did not lead to destruction up to 10 7 times of pressure repeat end. Further, the result of the bending vibration fatigue strength test was greatly improved as shown by the solid line in FIG.
【００３１】実施例４ 内管として実施例３と同一寸法で同一材質のステンレス
鋼管を３回の芯引きして伸管加工により縮径した後、実
施例１と同様の手順で厚さ８０μｍの窒化層を形成し
た。この際該窒化層の硬度（Ｈｖ）は６００であった。
ついで実施例３と同様の寸法と材質の外管内部に前記内
管を緩やかに内挿せしめて外管とともに内管を僅かに縮
径するようダイスを用いて空引きにより伸管加工を行
い、その後矯正加工して外径８．０ｍｍ、内径２．４ｍ
ｍ、肉厚２．８ｍｍ（断面減少率：約３％）の二重金属
管からなる噴射管材を得、しかる後に３００ｍｍの長さ
に切断した試料を２０本準備した。Example 4 A stainless steel tube of the same dimensions and the same material as that of Example 3 was drawn as an inner tube three times and reduced in diameter by a drawing process. A nitride layer was formed. At this time, the hardness (Hv) of the nitrided layer was 600.
Then, the inner pipe was gently inserted into the outer pipe having the same dimensions and material as in Example 3, and the outer pipe was stretched by drawing using a die so as to slightly reduce the diameter of the inner pipe together with the outer pipe. Straightening processing, outer diameter 8.0mm, inner diameter 2.4m
m, an injection tube made of a double metal tube having a wall thickness of 2.8 mm (cross-section reduction rate: about 3%), and then 20 samples cut to a length of 300 mm were prepared.
【００３２】このように準備した２０本の二重金属管か
らなる噴射管材について実施例１と同様のキャビテーシ
ョン試験と内圧繰返し疲労強度試験を行った結果、得ら
れた全ての試料試料について試験終了後にエロージョン
の発生は見られず、また１０７回の圧力繰返し終了まで
破壊には至らなかった。さらに曲げ振動疲労強度試験の
結果も図３の実線に示すように大幅に向上した。As a result of the same cavitation test and internal pressure repeated fatigue strength test as in Example 1 performed on the injection pipe material composed of 20 double metal pipes prepared as described above, all the obtained sample samples were subjected to erosion after the test was completed. of occurrence was not observed, also did not lead to destruction up to 10 7 times of pressure repeat end. Further, the result of the bending vibration fatigue strength test was greatly improved as shown by the solid line in FIG.
【００３３】比較例３ 内管として比較例１と同一の寸法であるがＳＵＳ ３０
４からなるステンレス鋼管を３回の芯引きして伸管加工
により縮径した。一方比較例１と同様の寸法であるがＳ
ＴＳ ４１０に相当する鋼管からなる外管の内部に前記
内管を緩やかに内挿せしめた。その後固定したダイスを
用いて前記内外管を圧嵌するよう両管を同時かつ一体的
に空引きによる伸管加工を２回行って縮径せしめ、つい
で矯正加工して外径８．０ｍｍ、内径２．５ｍｍ、肉厚
２．７５ｍｍの二重金属管からなる噴射管材を得、しか
る後に３００ｍｍの長さに切断した試料を２０本準備し
た。なお得られた試料における内管の硬度（Ｈｖ）は４
３０であった。COMPARATIVE EXAMPLE 3 The inner tube has the same dimensions as Comparative Example 1, but SUS 30
The stainless steel tube made of No. 4 was drawn three times and reduced in diameter by drawing. On the other hand, the dimensions are the same as those of Comparative Example 1, but S
The inner pipe was gently inserted into an outer pipe made of a steel pipe corresponding to TS410. Thereafter, the two pipes are simultaneously and integrally drawn twice to reduce the diameter so as to press-fit the inner and outer pipes by using a fixed die to reduce the diameter. An injection tube made of a double metal tube having a thickness of 2.5 mm and a thickness of 2.75 mm was obtained, and then 20 samples cut to a length of 300 mm were prepared. The hardness (Hv) of the inner tube in the obtained sample was 4
30.
【００３４】このように準備した２０本の二重金属管か
らなる噴射管材について、実施例１と同様にして２００
時間のキャビテーション試験を行なった結果、エロージ
ョンの発生したものが見られた。また実施例１と同様に
して内圧繰返し疲労強度試験を行ったが内管に破壊に至
るものが見られた。さらに曲げ振動疲労強度試験の結果
も図３の一点鎖線に示すように劣っていることが分かっ
た。In the same manner as in the first embodiment, the injection pipe made of 20 double metal pipes thus prepared
As a result of a time cavitation test, erosion was observed. An internal pressure repeated fatigue strength test was carried out in the same manner as in Example 1, but it was found that the inner pipe was broken. Further, it was also found that the results of the bending vibration fatigue strength test were inferior as shown by the dashed line in FIG.
【００３５】比較例４ 比較例３と同様の寸法と材質の内管と外管を用いて、比
較例３と同様に両管を同時に、かつ一体的に空引きによ
る伸管加工を１回行って縮径せしめ（断面減少率：約３
２％）、ついで矯正加工して噴射管材を得、しかる後に
３００ｍｍの長さに切断した試料を２０本準備した。た
だし肉厚は２．８ｍｍとした。COMPARATIVE EXAMPLE 4 Using the inner pipe and the outer pipe having the same dimensions and materials as those of Comparative Example 3, both pipes are simultaneously and integrally subjected to a single drawing operation by vacuum drawing as in Comparative Example 3. And reduce the diameter (section reduction rate: about 3
2%), and then straightened to obtain an injection tube, and thereafter, 20 samples cut to a length of 300 mm were prepared. However, the thickness was 2.8 mm.
【００３６】このように準備した２０本の二重金属管か
らなる噴射管材について、実施例１と同様にして２００
時間のキャビテーション試験を行なった結果、エロージ
ョンの発生したものが見られた。また実施例１と同様に
して内圧繰返し疲労強度試験を行ったが内管に破壊に至
るものが見られた。さらに曲げ振動疲労強度試験の結果
も図３の一点鎖線に示すように劣っていることが分かっ
た。The injection pipe made of 20 double metal pipes prepared in this manner was subjected to 200 injection pipes in the same manner as in the first embodiment.
As a result of a time cavitation test, erosion was observed. An internal pressure repeated fatigue strength test was carried out in the same manner as in Example 1, but it was found that the inner pipe was broken. Further, it was also found that the results of the bending vibration fatigue strength test were inferior as shown by the dashed line in FIG.
【００３７】[0037]
【発明の効果】以上述べた通り本発明によれば、内圧６
００〜１０００ｂａｒ（ピーク圧）という現在の燃料噴
射条件より過酷な管内ピーク圧が１２００ｂａｒを超え
かつ負圧を含むような特殊な噴射条件下でも内圧繰返し
疲労強度や曲げ振動疲労強度を向上することができると
ともに、その内周面において十分な耐エロージョン性能
を発揮し得る高圧燃料噴射管の製造方法および高圧燃料
噴射管を提供することができるものである。As described above, according to the present invention, the internal pressure 6
It is possible to improve the internal pressure cyclic fatigue strength and bending vibration fatigue strength even under special injection conditions in which the pipe peak pressure exceeding 1200 bar and including a negative pressure, which is more severe than the current fuel injection condition of 00 to 1000 bar (peak pressure). It is possible to provide a method of manufacturing a high-pressure fuel injection pipe and a high-pressure fuel injection pipe capable of exhibiting sufficient erosion resistance on the inner peripheral surface thereof.
【図１】本発明の高圧燃料噴射管の一実施例を示す正面
図である。FIG. 1 is a front view showing one embodiment of a high-pressure fuel injection pipe of the present invention.
【図２】本発明のその製造方法を示す図で、（ａ）は内
管の伸管加工を示す部分概略説明図、（ｂ）は内管と外
管を重合する伸管加工を示す部分概略説明図である。FIGS. 2A and 2B are diagrams showing the manufacturing method of the present invention, in which FIG. 2A is a partial schematic explanatory view showing the drawing of an inner tube, and FIG. FIG.
【図３】本発明の高圧燃料噴射管と従来の高圧燃料噴射
管との曲げ振動疲労強度とを示すため曲げ破壊までの振
動サイクルと繰返し応力との関係を示すグラフ図であ
る。FIG. 3 is a graph showing the relationship between the vibration cycle up to bending failure and the repetitive stress in order to show the bending vibration fatigue strength of the high-pressure fuel injection pipe of the present invention and the conventional high-pressure fuel injection pipe.
１ 外管 ２ 内管 ３ 窒化層 ４ スリーブワッシャー ５ 締付けナット ６ プラグ ７、８ ダイス Reference Signs List 1 outer tube 2 inner tube 3 nitride layer 4 sleeve washer 5 tightening nut 6 plug 7, 8 die
Claims (7)
硬質の薄肉の鋼管からなる内管を内挿せしめ伸管加工を
実施して二重金属管を形成する方法において、前記内管
を製品寸法まで芯引きによる伸管加工によって縮径し、
ついで該内管の内周面側に窒化処理を施し、その後この
ようにして内周面側に窒化層を形成された内管を外管内
に内挿し、空引きによる伸管加工によって前記外管のみ
を縮径せしめ該外管の内周面を前記内管の外周面に少な
くとも密着せしめたことを特徴とする高圧燃料噴射管の
製造方法。1. A method for forming a double metal pipe by inserting an inner pipe made of a thin steel pipe harder than the outer pipe into an outer pipe made of a thick steel pipe and performing a drawing process to form a double metal pipe. The diameter of the pipe is reduced to the product size by core drawing,
Next, a nitriding treatment is performed on the inner peripheral surface side of the inner pipe, and then the inner pipe having the nitrided layer formed on the inner peripheral surface side is inserted into the outer pipe, and the outer pipe is formed by drawing by drawing. A method for manufacturing a high-pressure fuel injection pipe, characterized in that only the diameter of the outer pipe is reduced and the inner peripheral surface of the outer pipe is brought into close contact with the outer peripheral face of the inner pipe.
硬質の薄肉の鋼管からなる内管を内挿せしめ伸管加工を
実施して二重金属管を形成する方法において、前記内管
をほぼ製品寸法まで芯引きによる伸管加工によって縮径
し、ついで該内管の内周面側に窒化処理を施し、その後
このようにして内周面側に窒化層を形成された内管を外
管内に内挿し、空引きによる伸管加工によって前記外管
を縮径せしめるとともに、前記内管を僅かに縮径して前
記外管の内周面を該内管の外周面に少なくとも密着せし
めたことを特徴とする高圧燃料噴射管の製造方法。2. A method of forming a double metal pipe by inserting an inner pipe made of a thin steel pipe harder than the outer pipe into an outer pipe made of a thick steel pipe and performing a drawing process to form a double metal pipe. The pipe is reduced in diameter to a product size by core drawing and then subjected to a nitriding treatment on the inner peripheral side of the inner pipe, and then the inner pipe having a nitrided layer formed on the inner peripheral side in this manner. Is inserted into the outer tube, and the outer tube is reduced in diameter by drawing by evacuation, and the inner tube is slightly reduced in diameter so that the inner peripheral surface of the outer tube is at least closely attached to the outer peripheral surface of the inner tube. A method for manufacturing a high-pressure fuel injection pipe, characterized in that:
ン）が１０％以下となるよう縮径することを特徴とする
請求項２記載の高圧燃料噴射管の製造方法3. The method for manufacturing a high-pressure fuel injection pipe according to claim 2, wherein the inner pipe is reduced in diameter so that a reduction rate of the cross section is 10% or less.
あるいはイオン窒化法により実施することを特徴とする
請求項１〜３のいずれか１項記載の高圧燃料噴射管の製
造方法。4. The method for manufacturing a high-pressure fuel injection pipe according to claim 1, wherein the nitriding treatment is performed by a gas nitriding method, a salt bath nitriding method, or an ion nitriding method.
としたことを特徴とする請求項１〜４のいずれか１記載
の高圧燃料噴射管の製造方法。5. The method according to claim 1, wherein the hardness (Hv) of the nitride layer is 800 or less.
硬質の薄肉の鋼管からなる内管を嵌合して形成した二重
金属管において、空引きによる伸管加工によって縮径さ
れた外管の内周面が少なくとも密着してなる前記内管の
内周面側に窒化層を有してなることを特徴とする高圧燃
料噴射管。6. A double metal pipe formed by fitting an inner pipe made of a thin steel pipe harder than the outer pipe to an outer pipe made of a thicker steel pipe, the diameter of which is reduced by drawing by drawing. A high-pressure fuel injection pipe comprising a nitride layer on the inner circumference side of the inner pipe in which the inner circumference of the outer pipe is in close contact.
であることを特徴とする請求項６記載の高圧燃料噴射
管。7. The high-pressure fuel injection pipe according to claim 6, wherein the nitride layer has a hardness (Hv) of 800 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06936098A JP4183146B2 (en) | 1997-09-30 | 1998-03-04 | High pressure fuel injection pipe manufacturing method and high pressure fuel injection pipe |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9-282514 | 1997-09-30 | ||
| JP28251497 | 1997-09-30 | ||
| JP06936098A JP4183146B2 (en) | 1997-09-30 | 1998-03-04 | High pressure fuel injection pipe manufacturing method and high pressure fuel injection pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11166673A true JPH11166673A (en) | 1999-06-22 |
| JP4183146B2 JP4183146B2 (en) | 2008-11-19 |
Family
ID=26410560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06936098A Expired - Fee Related JP4183146B2 (en) | 1997-09-30 | 1998-03-04 | High pressure fuel injection pipe manufacturing method and high pressure fuel injection pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4183146B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001040694A2 (en) * | 1999-12-01 | 2001-06-07 | Ti Group Automotive Systems Limited | Pressurized fluid pipe |
| JP2008141863A (en) * | 2006-12-01 | 2008-06-19 | Denso Corp | Piezoelectric actuator |
| JP2012076129A (en) * | 2010-10-04 | 2012-04-19 | Sumitomo Metal Ind Ltd | Method for manufacturing metallic double wall pipe |
-
1998
- 1998-03-04 JP JP06936098A patent/JP4183146B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001040694A2 (en) * | 1999-12-01 | 2001-06-07 | Ti Group Automotive Systems Limited | Pressurized fluid pipe |
| WO2001040694A3 (en) * | 1999-12-01 | 2002-05-10 | Ti Group Automotive Sys Ltd | Pressurized fluid pipe |
| JP2008141863A (en) * | 2006-12-01 | 2008-06-19 | Denso Corp | Piezoelectric actuator |
| JP2012076129A (en) * | 2010-10-04 | 2012-04-19 | Sumitomo Metal Ind Ltd | Method for manufacturing metallic double wall pipe |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4183146B2 (en) | 2008-11-19 |
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