WO2020004286A1 - Method for manufacturing hollow engine valve - Google Patents

Method for manufacturing hollow engine valve Download PDF

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Publication number
WO2020004286A1
WO2020004286A1 PCT/JP2019/024806 JP2019024806W WO2020004286A1 WO 2020004286 A1 WO2020004286 A1 WO 2020004286A1 JP 2019024806 W JP2019024806 W JP 2019024806W WO 2020004286 A1 WO2020004286 A1 WO 2020004286A1
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Prior art keywords
cylindrical portion
engine valve
spinning
hollow engine
manufacturing
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PCT/JP2019/024806
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French (fr)
Japanese (ja)
Inventor
敏夫 池田
守利 木村
豊 渡部
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株式会社東亜鍛工所
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Application filed by 株式会社東亜鍛工所 filed Critical 株式会社東亜鍛工所
Priority to JP2019570144A priority Critical patent/JP6719142B2/en
Priority to EP19827277.5A priority patent/EP3815811A4/en
Publication of WO2020004286A1 publication Critical patent/WO2020004286A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D53/00—Making other particular articles
    • B21D53/84—Making other particular articles other parts for engines, e.g. connecting-rods
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/14—Spinning
    • B21D22/16—Spinning over shaping mandrels or formers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/20—Deep-drawing
    • B21D22/28—Deep-drawing of cylindrical articles using consecutive dies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/20—Making machine elements valve parts
    • B21K1/22—Making machine elements valve parts poppet valves, e.g. for internal-combustion engines
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/60—Aqueous agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0062—Heat-treating apparatus with a cooling or quenching zone
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/12—Cooling of valves
    • F01L3/14—Cooling of valves by means of a liquid or solid coolant, e.g. sodium, in a closed chamber in a valve
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2301/00—Using particular materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2303/00—Manufacturing of components used in valve arrangements
    • F01L2303/01—Tools for producing, mounting or adjusting, e.g. some part of the distribution
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2820/00—Details on specific features characterising valve gear arrangements
    • F01L2820/01—Absolute values

Definitions

  • the processing roller 32 is rotatably supported by the support member 35 via the front and rear bearings 34 disposed along the axial direction of the processing roller 32 with the processing roller 32 interposed therebetween.
  • the support member 35 can be moved in the radial direction and the axial direction of the cylindrical portion 8B by a moving mechanism (not shown). Note that one or a plurality of the processing rollers 32 may be used.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Forging (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)

Abstract

Provided is a method for manufacturing a hollow engine valve, whereby the surface state of an inside surface for forming a hollow hole is satisfactory, and the volume of the hollow hole can be increased. This manufacturing method is provided with a forging step (S3) for obtaining an intermediate component (7) provided with a cylindrical part (8B) and a half-umbrella-shaped part (9B) continuous with a shaft-end side of the cylindrical part by a forging process, a heat treatment step (S4) for heat treating the intermediate component for a heating retention time (t2) determined in accordance with the wall thickness (t) of the cylindrical part (8B) to soften the intermediate components, a spinning step (S5) for elongating the cylindrical part of the heat-treated intermediate component in the axial direction by a spinning process, and a necking step (S6) for forming a shaft part (2) and an umbrella-shaped part (3) by reducing the diameter of the axially elongated cylindrical part by a drawing process.

Description

中空エンジンバルブの製造方法Manufacturing method of hollow engine valve
　本発明は、中空エンジンバルブの製造方法に関し、更に詳しくは、軸部及び該軸部の軸端側に連なる傘状部を備え、軸部及び傘状部にわたって中空孔が形成された中空エンジンバルブの製造方法に関する。 The present invention relates to a method for manufacturing a hollow engine valve, and more particularly, to a hollow engine valve including a shaft portion and an umbrella-shaped portion connected to the shaft end side of the shaft portion, wherein a hollow hole is formed over the shaft portion and the umbrella-shaped portion. And a method for producing the same.
　従来の中空エンジンバルブの製造方法として、鍛造加工により、円筒状部及び該円筒状部の軸端側に連なる半傘状部を備える中間部品を製造し、その中間部品の円筒状部をスピニング加工した後に絞り加工して縮径することで、中空エンジンバルブを製造する方法が記載されている（特許文献１の請求項５及び明細書の段落〔００２３〕等参照）。 As a conventional method for manufacturing a hollow engine valve, an intermediate component having a cylindrical portion and a semi-umbrella-shaped portion connected to the shaft end side of the cylindrical portion is manufactured by forging, and the cylindrical portion of the intermediate component is spinned. A method of manufacturing a hollow engine valve by drawing and reducing the diameter after the drawing is described (see claim 5 of Patent Document 1 and paragraph [0023] of the specification).
国際公開第２０１１／１０４９０３号公報International Publication No. 2011/104903
　しかし、上記従来の中空エンジンバルブの製造方法では、鍛造加工により得られた中間部品を文献・資料等と作業者の経験に基づいて決められる加熱保持時間で熱処理し、その熱処理された中間部品の円筒状部をスピニング加工しているため、スピニング加工時に中間部品の円筒状部が伸び難くい場合がある。その場合、中間部品の円筒状部において加工面（すなわち、円筒状部の外周面）と加工用ツールが接触しない内周面との間で表面状態が異なる。具体的に、中間部品の円筒状部の内周面、ひいては中空エンジンバルブの中空孔を形成する内面には肌荒れが生じて表面状態が悪くなる。そのため、中空エンジンバルブの強度が低下してしまう。さらに、中空エンジンバルブの中空孔内に冷却用の金属ナトリウムを入れることがあるが、その場合、中空孔内での金属ナトリウムの流動性が低く冷却機能が低下してしまう。
　なお、上述の問題は、特にオーステナイト系耐熱材料（例えば、ニッケル基超合金、オーステナイト系ステンレス鋼等）の難加工材を加工する場合に顕著に現れる。 However, in the above-described conventional method for manufacturing a hollow engine valve, the intermediate part obtained by forging is heat-treated for a heating and holding time determined based on literature, materials, and the experience of the operator, and the heat-treated intermediate part is heated. Since the cylindrical portion is subjected to spinning, the cylindrical portion of the intermediate part may not be easily stretched during spinning. In that case, the surface condition is different between the processing surface (that is, the outer peripheral surface of the cylindrical portion) of the cylindrical portion of the intermediate part and the inner peripheral surface where the processing tool does not contact. Specifically, the inner peripheral surface of the cylindrical portion of the intermediate part, and eventually the inner surface of the hollow engine valve forming the hollow hole, is roughened and the surface condition is deteriorated. Therefore, the strength of the hollow engine valve is reduced. Further, in some cases, metallic sodium for cooling is put into the hollow hole of the hollow engine valve, but in that case, the fluidity of metallic sodium in the hollow hole is low and the cooling function is reduced.
In addition, the above-described problem is particularly conspicuous when a difficult-to-work material such as an austenitic heat-resistant material (eg, a nickel-based superalloy, an austenitic stainless steel, etc.) is processed.
　ここで、中空エンジンバルブでは、軽量化等のために中空孔の容積を大きくすることが求められる。しかしながら、上記従来の中空エンジンバルブの製造方法では、上述のように、鍛造加工により得られた中間部品を文献・資料等と作業者の経験に基づいて決められる加熱保持時間で熱処理し、その熱処理された中間部品の円筒状部をスピニング加工しているため、スピニング加工に加えて絞り加工時にも中間部品の円筒状部が伸び難い。そのため、加圧力が大きくなるように、中間部品の円筒状部の底端側まで深く金型で絞り加工する必要がある。その結果、中空エンジンバルブの傘状部の中空孔の外周側が潰れ易く、傘状部の中空孔の容積を大きくできない。 Here, in the case of a hollow engine valve, it is required to increase the volume of the hollow hole in order to reduce the weight. However, in the conventional method of manufacturing a hollow engine valve, as described above, the intermediate part obtained by forging is heat-treated for a heating and holding time determined based on literature, materials, and the experience of an operator. Since the cylindrical part of the intermediate part is spin-finished, the cylindrical part of the intermediate part does not easily stretch during drawing in addition to spinning. For this reason, it is necessary to draw with a metal mold deeply to the bottom end side of the cylindrical portion of the intermediate part so that the pressing force is increased. As a result, the outer peripheral side of the hollow hole of the umbrella-shaped portion of the hollow engine valve is easily crushed, and the volume of the hollow hole of the umbrella-shaped portion cannot be increased.
　本発明は、上記現状に鑑みてなされたものであり、中空孔を形成する内面での表面状態が良好であるとともに、中空孔の容積を大きくすることができる中空エンジンバルブの製造方法を提供することを目的とする。 The present invention has been made in view of the above situation, and provides a method of manufacturing a hollow engine valve which has a good surface condition on an inner surface forming a hollow hole and can increase the volume of the hollow hole. The purpose is to:
　本発明は以下の通りである。
　１．軸部及び該軸部の軸端側に連なる傘状部を備え、前記軸部及び前記傘状部にわたって中空孔が形成された中空エンジンバルブの製造方法であって、鍛造加工により、円筒状部及び該円筒状部の軸端側に連なる半傘状部を備える中間部品を得る鍛造工程と、前記中間部品を軟化させるために前記円筒状部の肉厚に応じて決められる加熱保持時間で熱処理する熱処理工程と、熱処理された前記中間部品の前記円筒状部をスピニング加工により軸方向に延伸するスピニング工程と、軸方向に延伸された前記円筒状部を絞り加工により縮径することで、前記軸部及び前記傘状部を形成するネッキング工程と、を備えることを要旨とする。
　２．前記中間部品は、オーステナイト系耐熱材料で形成されており、前記熱処理工程は、前記中間部品を１０００～１１００℃に加熱保持した後に水冷する上記１．記載の中空エンジンバルブの製造方法。
　３．前記熱処理工程は、加熱された前記中間部品を前記円筒状部の肉厚の１ｍｍ当りに対して３～８分となる加熱保持時間で保持する上記２．記載の中空エンジンバルブの製造方法。
　４．前記熱処理工程は、前記中間部品を、容器内で攪拌される冷却水中又は容器に対して循環される冷却水中に投入して水冷する上記２．又は３．に記載の中空エンジンバルブの製造方法。
　５．前記冷却水の水温は、１５～３５℃である上記４．記載の中空エンジンバルブの製造方法。
　６．前記スピニング工程は、前記円筒状部の外周面に加工ローラの外周円弧面を所定の切込み量で押し当てながら、前記加工ローラを前記円筒状部に対して軸方向に移動させて前記円筒状部を軸方向に延伸し、前記加工ローラの外周円弧面の曲率半径は、スピニング加工前の前記円筒状部の肉厚の３～５倍の値であり、前記スピニング加工時に、前記円筒状部の軸方向に沿う断面において、前記加工ローラの外周円弧面が前記円筒状部の外周面と接する円弧の一端と他端とを結ぶ直線は、前記円筒状部の軸方向に対して５～７度の傾斜角度で傾斜している上記１．乃至５．のいずれか一項に記載の中空エンジンバルブの製造方法。
　７．前記中空エンジンバルブは、前記中空孔を形成する内面の表面粗さＲａが４．０～２２．０である上記１．乃至６．のいずれか一項に記載の中空エンジンバルブの製造方法。
　８．前記鍛造工程は、前記中間部品の前記円筒状部の内周面の底端側に円弧面を形成し、前記ネッキング工程は、前記円筒状部を上側とし且つ前記半傘状部を下側としたときに、前記円筒状部の軸方向で前記円弧面よりも上側の部分を絞り加工する上記１．乃至７．のいずれか一項に記載の中空エンジンバルブの製造方法。
　９．前記スピニング工程は、加工ローラを用いて前記中間部品の前記円筒状部をスピニング加工し、前記加工ローラは、該加工ローラを挟んで該加工ローラの軸方向に沿って配置される前後の軸受を介して支持部材に回転自在に支持されている上記１．乃至８．のいずれか一項に記載の中空エンジンバルブの製造方法。 The present invention is as follows.
1. A method for manufacturing a hollow engine valve, comprising: a shaft portion and an umbrella-shaped portion connected to the shaft end side of the shaft portion, wherein a hollow hole is formed over the shaft portion and the umbrella-shaped portion. And a forging step of obtaining an intermediate part having a semi-umbrella-shaped part connected to the shaft end side of the cylindrical part, and a heat treatment for heating and holding time determined according to the thickness of the cylindrical part to soften the intermediate part. Heat treatment step, and a spinning step of extending the heat-treated intermediate part in the axial direction by spinning the cylindrical part, and reducing the diameter of the axially-extended cylindrical part by drawing. A necking step of forming a shaft portion and the umbrella-shaped portion.
2. The intermediate part is formed of an austenitic heat-resistant material, and in the heat treatment step, the intermediate part is heated and held at 1000 to 1100 ° C. and then water-cooled. A method for manufacturing the hollow engine valve according to the above.
3. In the heat treatment step, the heated intermediate component is held for a heating holding time of 3 to 8 minutes per 1 mm of the thickness of the cylindrical portion. A method for manufacturing the hollow engine valve according to the above.
4. In the heat treatment step, the intermediate component is placed in cooling water stirred in a container or cooling water circulated in the container, and water-cooled. Or 3. 5. The method for manufacturing a hollow engine valve according to item 1.
5. 3. The temperature of the cooling water is 15 to 35 ° C. A method for manufacturing the hollow engine valve according to the above.
6. The spinning step includes moving the processing roller in the axial direction with respect to the cylindrical portion while pressing an outer circular arc surface of the processing roller against the outer peripheral surface of the cylindrical portion by a predetermined cut amount. In the axial direction, the radius of curvature of the outer circumferential arc surface of the processing roller is 3 to 5 times the thickness of the cylindrical portion before spinning, and at the time of the spinning, In a cross section along the axial direction, a straight line connecting one end and the other end of the arc where the outer circumferential surface of the processing roller contacts the outer circumferential surface of the cylindrical portion is 5 to 7 degrees with respect to the axial direction of the cylindrical portion. The above-mentioned 1. which is inclined at an inclination angle of 1. To 5. The method for manufacturing a hollow engine valve according to any one of claims 1 to 3.
7. In the hollow engine valve, the inner surface forming the hollow hole has a surface roughness Ra of 4.0 to 22.0. To 6. The method for manufacturing a hollow engine valve according to any one of claims 1 to 3.
8. The forging step forms an arc surface on the bottom end side of the inner peripheral surface of the cylindrical part of the intermediate part, and the necking step sets the cylindrical part to the upper side and the semi-umbrella part to the lower side. Then, a portion above the arc surface in the axial direction of the cylindrical portion is drawn. To 7. The method for manufacturing a hollow engine valve according to any one of claims 1 to 3.
9. The spinning step spins the cylindrical portion of the intermediate component using a processing roller, and the processing roller includes front and rear bearings that are arranged along the axial direction of the processing roller with the processing roller interposed therebetween. 1 above, which is rotatably supported by the support member via To 8. The method for manufacturing a hollow engine valve according to any one of claims 1 to 3.
　本発明の中空エンジンバルブの製造方法によると、鍛造加工により、円筒状部及び該円筒状部の軸端側に連なる半傘状部を備える中間部品を得る鍛造工程と、中間部品を軟化させるために前記円筒状部の肉厚に応じて決められる加熱保持時間で熱処理する熱処理工程と、熱処理された中間部品の円筒状部をスピニング加工により軸方向に延伸するスピニング工程と、軸方向に延伸された円筒状部を絞り加工により縮径することで、軸部及び傘状部を形成するネッキング工程と、を備える。このように、鍛造加工により得られた中間部品を熱処理して軟化させることで、スピニング加工時及び絞り加工時に中間部品の円筒状部が伸び易くなるため、スピニング加工及び絞り加工の加工性に優れる。その結果、中空エンジンバルブの中空孔を形成する内面での表面肌荒れの発生が抑制されて表面状態が良好となる。よって、中空エンジンバルブの強度の低下が抑制される。さらに、中空エンジンバルブの中空孔内に冷却用の金属ナトリウムを入れる場合には、中空孔内で金属ナトリウムが円滑に流動して効果的に冷却機能を発揮する。さらに、絞り加工の加工性に優れるため、傘状部の中空孔の外周側の潰れが抑制されるように、絞り加工の型締め時の金型の高さ位置を容易に調整できる。その結果、中空エンジンバルブの中空孔の容積を大きくすることができる。
　また、前記中間部品が、オーステナイト系耐熱材料で形成されており、前記熱処理工程が、前記中間部品を１０００～１１００℃に加熱保持した後に水冷する場合は、中間部品を固溶化熱処理して効果的に軟化させることができる。
　また、前記熱処理工程が、加熱された前記中間部品を前記円筒状部の肉厚の１ｍｍ当りに対して３～８分となる加熱保持時間で保持する場合は、中間部品の加熱保持時間を比較的短くでき、熱処理後の中間部品の表面での酸化膜の発生を低減できる。
　また、前記熱処理工程が、前記中間部品を、容器内で攪拌される冷却水中又は容器に対して循環される冷却水中に投入して水冷する場合は、冷却水の温度上昇が抑えられるため、熱処理工程で中間部品を効果的に急冷できる。
　また、前記冷却水の水温が、１５～３５℃である場合は、熱処理工程で中間部品を効果的に急冷できる。
　また、前記スピニング工程が、前記円筒状部の外周面に加工ローラの外周円弧面を所定の切込み量で押し当てながら、前記加工ローラを前記円筒状部に対して軸方向に移動させて前記円筒状部を軸方向に延伸し、前記加工ローラの外周円弧面の曲率半径が、スピニング加工前の前記円筒状部の肉厚の３～５倍の値であり、前記スピニング加工時に、前記円筒状部の軸方向に沿う断面において、前記加工ローラの外周円弧面が前記円筒状部の外周面と接する円弧の一端と他端とを結ぶ直線が、前記円筒状部の軸方向に対して５～７度の傾斜角度で傾斜している場合は、切込み量の最大値と最小値を想定考慮して加工ローラの外周円弧面の曲率半径を設定することとなるため、スピニング加工時に中間部品の円筒状部を効果的に延伸できる。
　また、前記中空エンジンバルブが、前記中空孔を形成する内面の表面粗さＲａが４．０～２２．０である場合は、中空エンジンバルブの中空孔を形成する内面の表面状態が極めて良好である。
　また、前記鍛造工程が、前記中間部品の前記円筒状部の内周面の底端側に円弧面を形成し、前記ネッキング工程が、前記円筒状部を上側とし且つ前記半傘状部を下側としたきに、前記円筒状部の軸方向で前記円弧面よりも上側の部分を絞り加工する場合は、中空エンジンバルブの中空孔の最大外径が鍛造加工で得られる中間部品の円筒状部の開口の内径と略同じにできる。その結果、中空エンジンバルブの中空孔の容積を更に大きくできる。
　さらに、前記スピニング工程が、加工ローラを用いて前記中間部品の前記円筒状部をスピニング加工し、前記加工ローラが、該加工ローラを挟んで該加工ローラの軸方向に沿って配置される前後の軸受を介して支持部材に回転自在に支持されている場合は、加工ローラの倒れ込みが抑制されるため、中間部品の円筒状部が効果的にスピニング加工される。 According to the method for manufacturing a hollow engine valve of the present invention, a forging process for obtaining an intermediate part having a cylindrical part and a semi-umbrella-shaped part connected to the shaft end side of the cylindrical part, and for softening the intermediate part A heat treatment step of performing a heat treatment for a heating and holding time determined according to the thickness of the cylindrical part, a spinning step of extending the cylindrical part of the heat-treated intermediate part in the axial direction by spinning, A necking step of forming a shaft portion and an umbrella-shaped portion by reducing the diameter of the cylindrical portion by drawing. As described above, by heat-treating and softening the intermediate part obtained by forging, the cylindrical part of the intermediate part is easily elongated at the time of spinning and drawing, and is excellent in workability of spinning and drawing. . As a result, the occurrence of surface roughening on the inner surface of the hollow engine valve forming the hollow hole is suppressed, and the surface condition is improved. Therefore, a decrease in the strength of the hollow engine valve is suppressed. Further, when metal sodium for cooling is put in the hollow hole of the hollow engine valve, the metal sodium flows smoothly in the hollow hole and effectively exerts a cooling function. Further, since the drawing processability is excellent, the height position of the mold at the time of the drawing die clamping can be easily adjusted so that the outer peripheral side of the hollow hole of the umbrella-shaped portion is suppressed. As a result, the volume of the hollow hole of the hollow engine valve can be increased.
In the case where the intermediate component is formed of an austenitic heat-resistant material and the heat treatment step is performed by heating and holding the intermediate component at 1000 to 1100 ° C. and then cooling with water, the intermediate component is effectively subjected to a solution heat treatment. Can be softened.
In the case where the heat treatment step holds the heated intermediate part for a heating holding time of 3 to 8 minutes per 1 mm of the thickness of the cylindrical portion, the heating holding time of the intermediate part is compared. It is possible to reduce the length of the oxide film on the surface of the intermediate component after the heat treatment.
Further, in the case where the heat treatment step is performed in which the intermediate component is put into cooling water stirred in a container or cooling water circulated in the container and water-cooled, the temperature rise of the cooling water is suppressed. The intermediate parts can be quenched effectively in the process.
When the temperature of the cooling water is 15 to 35 ° C., the intermediate part can be cooled rapidly in the heat treatment step.
Further, the spinning step includes moving the processing roller in the axial direction with respect to the cylindrical portion while pressing an outer circular arc surface of the processing roller against the outer peripheral surface of the cylindrical portion by a predetermined cutting amount. The radius of curvature of the outer peripheral arc surface of the processing roller is 3 to 5 times the thickness of the cylindrical part before spinning, and the cylindrical part is stretched during the spinning. In a cross section along the axial direction of the portion, a straight line connecting one end and the other end of an arc in which the outer peripheral arc surface of the processing roller contacts the outer peripheral surface of the cylindrical portion is 5 to 5 with respect to the axial direction of the cylindrical portion. In the case of inclination at an inclination angle of 7 degrees, the radius of curvature of the outer peripheral arc surface of the processing roller is set in consideration of the maximum value and the minimum value of the cutting amount. The shape can be effectively stretched.
Further, when the hollow engine valve has a surface roughness Ra of 4.0 to 22.0 on the inner surface forming the hollow hole, the surface condition of the inner surface forming the hollow hole of the hollow engine valve is extremely good. is there.
Further, the forging step forms an arc surface on the bottom end side of the inner peripheral surface of the cylindrical part of the intermediate part, and the necking step sets the cylindrical part upward and the semi-umbrella downward. When the upper part of the hollow portion of the hollow engine valve is obtained by forging, when the portion above the arc surface is drawn in the axial direction of the cylindrical portion, the cylindrical shape of the intermediate part is obtained. It can be made substantially the same as the inner diameter of the opening of the part. As a result, the volume of the hollow hole of the hollow engine valve can be further increased.
Furthermore, the spinning step spins the cylindrical portion of the intermediate component using a processing roller, and before and after the processing roller is disposed along the axial direction of the processing roller across the processing roller. When the support member is rotatably supported by a support member via a bearing, the falling of the processing roller is suppressed, so that the cylindrical portion of the intermediate component is effectively spinned.
　本発明について、本発明による典型的な実施形態の非限定的な例を挙げ、言及された複数の図面を参照しつつ以下の詳細な記述にて更に説明するが、同様の参照符号は図面のいくつかの図を通して同様の部品を示す。
本実施例に係る中空エンジンバルブの製造方法を説明するための説明図である。 本実施例に係る中空エンジンバルブの製造方法を説明するための説明図であり、（ａ）は素材の縦断面を示し、（ｂ）は第１鍛造工程で得られる中間部品の縦断面を示し、（ｃ）はしごき工程を経た中間部品の縦断面を示す。 上記中空エンジンバルブの製造方法を説明するための説明図であり、（ａ）は第２鍛造工程を経た中間部品の縦断面を示し、（ｂ）はスピニング工程を経た中間部品の縦断面を示し、（ｃ）はネッキング工程で得られる中空エンジンバルブの縦断面を示す。 本実施例に係る熱処理工程を説明するための説明図である。 上記熱処理工程を説明するための説明図である。 上記スピニング工程を説明するための説明図である。 上記ネッキング工程を説明するための説明図であり、中心線の左側が絞り加工の直前の中間部品の縦断面を示し、中心線の右側が絞り加工の完了時の中空エンジンバルブの縦断面を示す。 他の形態のネッキング工程を説明するための説明図である。 本実施例に係る中空エンジンバルブの表面状態を説明するための説明図であり、（ａ）はスピニング工程を経た中間部品の要部の縦断面画像処理図を示し、（ｂ）は中空エンジンバルブの要部の縦断面画像処理図を示す。 比較例に係る中空エンジンバルブの表面状態を説明するための説明図であり、（ａ）はスピニング工程を経た中間部品の要部の縦断面画像処理図を示し、（ｂ）は中空エンジンバルブの要部の縦断面画像処理図を示す。 実験例１～７に係る中空エンジンバルブの製造方法の実験結果を示す表である。 実験例８～１３に係る中空エンジンバルブの製造方法の実験結果を示す表である。 実験例１４～１９及び比較例に係る中空エンジンバルブの製造方法の実験結果を示す表である。 他の形態のスピニング工程を説明するための説明図である。 図１４の要部拡大図である。 実験例に係るスピニング工程の実験結果を示す表であり、（ａ）は実験例２０～２４の実験結果を示し、（ｂ）は実験例２５～２７の実験結果を示す。 The invention will be further described in the following detailed description, given by way of non-limiting example of an exemplary embodiment according to the invention and with reference to the figures referred to, wherein like reference numerals being used in the figures. Similar parts are shown throughout the several figures.
FIG. 5 is an explanatory diagram for explaining the method for manufacturing the hollow engine valve according to the embodiment. It is explanatory drawing for demonstrating the manufacturing method of the hollow engine valve which concerns on a present Example, (a) shows the longitudinal section of a raw material, (b) shows the longitudinal section of the intermediate part obtained by a 1st forging process. (C) shows a longitudinal section of the intermediate part after the ironing step. It is explanatory drawing for demonstrating the manufacturing method of the said hollow engine valve, (a) shows the longitudinal section of the intermediate part which passed through the 2nd forging process, (b) shows the longitudinal cross section of the intermediate part which passed through the spinning process. (C) shows a longitudinal section of the hollow engine valve obtained in the necking step. FIG. 3 is an explanatory diagram for explaining a heat treatment step according to the embodiment. It is explanatory drawing for demonstrating the said heat processing process. It is an explanatory view for explaining the above-mentioned spinning process. It is explanatory drawing for demonstrating the said necking process, the left side of a center line shows the longitudinal section of the intermediate part immediately before a drawing process, and the right side of a center line shows the longitudinal section of the hollow engine valve at the time of completion of a drawing process. . It is explanatory drawing for demonstrating the necking process of another form. It is explanatory drawing for demonstrating the surface state of the hollow engine valve which concerns on a present Example, (a) is a longitudinal section image processing figure of the principal part of the intermediate part which passed through the spinning process, (b) is a hollow engine valve. 3 shows a vertical cross-sectional image processing diagram of a main part of FIG. It is explanatory drawing for demonstrating the surface state of the hollow engine valve which concerns on a comparative example, (a) shows the longitudinal section image processing figure of the principal part of the intermediate part which passed through the spinning process, (b) shows the hollow engine valve. The longitudinal section image processing figure of the principal part is shown. 9 is a table showing experimental results of a method for manufacturing a hollow engine valve according to Experimental Examples 1 to 7. 14 is a table showing experimental results of a method for manufacturing a hollow engine valve according to Experimental Examples 8 to 13. 20 is a table showing experimental results of a method for manufacturing a hollow engine valve according to Experimental Examples 14 to 19 and Comparative Example. It is explanatory drawing for demonstrating the spinning process of another form. It is a principal part enlarged view of FIG. It is a table | surface which shows the experimental result of the spinning process which concerns on an experimental example, (a) shows the experimental result of Experimental Examples 20-24, (b) shows the experimental result of Experimental Examples 25-27.
　ここで示される事項は例示的なものおよび本発明の実施形態を例示的に説明するためのものであり、本発明の原理と概念的な特徴とを最も有効に且つ難なく理解できる説明であると思われるものを提供する目的で述べたものである。この点で、本発明の根本的な理解のために必要である程度以上に本発明の構造的な詳細を示すことを意図してはおらず、図面と合わせた説明によって本発明の幾つかの形態が実際にどのように具現化されるかを当業者に明らかにするものである。 The matters shown here are for the purpose of exemplifying the exemplary embodiments and the embodiments of the present invention, and should be described so that the principles and conceptual features of the present invention can be most effectively and easily understood. It is intended to provide what is considered. In this regard, it is not intended to show the structural details of the invention beyond that which is necessary for a fundamental understanding of the invention, and that some forms of the invention will be It will be clear to those skilled in the art how it is actually embodied.
　本実施形態に係る中空エンジンバルブの製造方法は、軸部（２）及び該軸部の軸端側に連なる傘状部（３）を備え、軸部（２）及び傘状部（３）にわたって中空孔（４）が形成された中空エンジンバルブ（１）の製造方法であって、鍛造加工により、円筒状部（８Ｂ）及び該円筒状部の軸端側に連なる半傘状部（９Ｂ）を備える中間部品（７Ｃ）を得る鍛造工程（Ｓ３）と、中間部品（７Ｃ）を軟化させるために円筒状部（８Ｂ）の肉厚（ｔ）に応じて決められる加熱保持時間（ｔ２）で熱処理する熱処理工程（Ｓ４）と、熱処理された中間部品（７Ｃ）の円筒状部（８Ｂ）をスピニング加工により軸方向に延伸するスピニング工程（Ｓ５，Ｓ５’）と、軸方向に延伸された円筒状部（８Ｂ）を絞り加工により縮径することで、軸部（２）及び傘状部（３）を形成するネッキング工程（Ｓ６）と、を備える（例えば、図１～図３等参照）。 The method for manufacturing a hollow engine valve according to the present embodiment includes a shaft portion (2) and an umbrella-shaped portion (3) connected to the shaft end side of the shaft portion, and extends over the shaft portion (2) and the umbrella-shaped portion (3). A method for manufacturing a hollow engine valve (1) in which a hollow hole (4) is formed, comprising a cylindrical portion (8B) and a semi-umbrella-shaped portion (9B) connected to the shaft end side of the cylindrical portion by forging. In a forging step (S3) for obtaining an intermediate part (7C) having the following, and a heating holding time (t2) determined according to the thickness (t) of the cylindrical part (8B) to soften the intermediate part (7C). A heat treatment step (S4) for heat treatment, a spinning step (S5, S5 ') for extending the cylindrical part (8B) of the heat-treated intermediate part (7C) in the axial direction by spinning, and a cylinder elongated in the axial direction. The shaft portion (2) is formed by reducing the diameter of the shape portion (8B) by drawing. A necking step of forming a fine cone-shaped part (3) (S6), provided with a (for example, see FIGS. 1-3).
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、上記中間部品（７Ｃ）は、オーステナイト系耐熱材料で形成されており、熱処理工程（Ｓ４）は、中間部品（７Ｃ）を１０００～１１００℃（好ましくは１０３０～１０７０℃、特に１０４０～１０６０℃）に加熱保持した後に水冷する形態（例えば、図１１～図１３等参照）が挙げられる。なお、上記オーステナイト系耐熱材料としては、例えば、ＮＣＦ７５１（インコネル７５１（登録商標））等のニッケル基超合金、ＳＵＳ３０４等のステンレス鋼、ＳＵＨ３５、ＳＵＨ３８等の耐熱鋼等が挙げられる。 In the method for manufacturing the hollow engine valve according to the present embodiment, for example, the intermediate part (7C) is formed of an austenitic heat-resistant material, and the heat treatment step (S4) is performed by using the intermediate part (7C) of 1000 to 1100. A mode of heating and holding at a temperature of 10 ° C. (preferably 1030 to 1070 ° C., particularly 1040 to 1060 ° C.) and then cooling with water (for example, see FIGS. 11 to 13). Examples of the austenitic heat-resistant material include a nickel-based superalloy such as NCF751 (Inconel 751 (registered trademark)), a stainless steel such as SUS304, and a heat-resistant steel such as SUH35 and SUH38.
　上述の形態の場合、例えば、上記熱処理工程（Ｓ４）は、加熱された中間部品（７Ｃ）を円筒状部（８Ｂ）の肉厚（ｔ）の１ｍｍ当りに対して３～８分（好ましくは４～６分）となる加熱保持時間（ｔ２）で保持することができる（例えば、図１１～図１３等参照）。この場合、例えば、上記中間部品（７Ｃ）の円筒状部（８Ｂ）の肉厚（ｔ）は１～３ｍｍであり、熱処理工程（Ｓ４）は、加熱された中間部品（７Ｃ）を３～２４分（好ましくは４～１８分、特に５～１５分）の加熱保持時間で保持することができる。 In the case of the above-described embodiment, for example, in the heat treatment step (S4), the heated intermediate part (7C) is heated for 3 to 8 minutes (preferably, per mm) of the thickness (t) of the cylindrical portion (8B). (4 to 6 minutes) (see, for example, FIGS. 11 to 13). In this case, for example, the wall thickness (t) of the cylindrical portion (8B) of the intermediate part (7C) is 1 to 3 mm, and the heat treatment step (S4) is performed by heating the heated intermediate part (7C) to 3 to 24 mm. Minutes (preferably 4 to 18 minutes, especially 5 to 15 minutes).
　上述の形態の場合、例えば、上記熱処理工程（Ｓ４）は、中間部品（７Ｃ）を、容器（２２）内で攪拌される冷却水（２３）中又は容器に対して循環される冷却水中に投入して水冷することができる（例えば、図５等参照）。この場合、例えば、上記冷却水の水温は、１５～３５℃（好ましくは２０～３０℃）であることができる（例えば、図１１～図１３等参照）。 In the case of the above-described embodiment, for example, in the heat treatment step (S4), the intermediate component (7C) is put into cooling water (23) stirred in the container (22) or into cooling water circulated through the container. And water-cooled (see, for example, FIG. 5). In this case, for example, the water temperature of the cooling water can be 15 to 35 ° C. (preferably 20 to 30 ° C.) (see, for example, FIGS. 11 to 13).
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、図１４及び図１５に示すように、スピニング工程（Ｓ５’）は、円筒状部（８Ｂ）の外周面に加工ローラ（１３２）の外周円弧面（１３２ａ）を所定の切込み量（ｄ）で押し当てながら、加工ローラ（１３２）を円筒状部（８Ｂ）に対して軸方向に移動（相対的に移動）させて円筒状部（８Ｂ）を軸方向に延伸することができる。この場合、例えば、加工ローラ（１３２）の外周円弧面（１３２ａ）の曲率半径（Ｒ）は、スピニング加工前の円筒状部（８Ｂ）の肉厚（ｔ）の３～５倍の値であり、スピニング加工時に、円筒状部（８Ｂ）の軸方向に沿う断面において、加工ローラ（１３２）の外周円弧面（１３２ａ）が円筒状部（８Ｂ）の外周面と接する円弧の一端（ｐ１）と他端（ｐ２）とを結ぶ直線（Ｌ１）は、円筒状部（８Ｂ）の軸方向に対して５～７度の傾斜角度（θ１）で傾斜していることができる。 As a method for manufacturing the hollow engine valve according to the present embodiment, for example, as shown in FIGS. 14 and 15, the spinning step (S5 ′) includes the step of forming the processing roller (132) on the outer peripheral surface of the cylindrical portion (8B). The processing roller (132) is axially moved (moved relatively) with respect to the cylindrical portion (8B) while pressing the outer circular arc surface (132a) at a predetermined cutting amount (d), and the cylindrical portion ( 8B) can be stretched in the axial direction. In this case, for example, the radius of curvature (R) of the outer circular arc surface (132a) of the processing roller (132) is 3 to 5 times the thickness (t) of the cylindrical portion (8B) before spinning. At the time of spinning, in the cross section along the axial direction of the cylindrical portion (8B), one end (p1) of the circular arc where the outer peripheral arc surface (132a) of the processing roller (132) is in contact with the outer peripheral surface of the cylindrical portion (8B). The straight line (L1) connecting to the other end (p2) can be inclined at an inclination angle (θ1) of 5 to 7 degrees with respect to the axial direction of the cylindrical portion (8B).
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、上記中空エンジンバルブ（１）は、中空孔（４）を形成する内面の表面粗さＲａが４．０～２２．０（好ましくは４．０～１２．０、特に４．０～８．０、更に４．０～６．０）である形態（例えば、図９等参照）が挙げられる。なお、上記表面粗さは算術平均粗さ（Ｒａ）を採用した。また、上記表面粗さＲａは、ネッキング工程後の表面粗さを示す。 As a method for manufacturing the hollow engine valve according to the present embodiment, for example, the hollow engine valve (1) has a surface roughness Ra of 4.0 to 22.0 (preferably the inner surface forming the hollow hole (4)). 4.0 to 12.0, particularly 4.0 to 8.0, and more preferably 4.0 to 6.0) (for example, see FIG. 9 and the like). In addition, arithmetic mean roughness (Ra) was adopted as the surface roughness. The surface roughness Ra indicates the surface roughness after the necking step.
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、上記鍛造工程（Ｓ３）は、中間部品（７Ｃ）の円筒状部（８Ｂ）の内周面の底端側に円弧面（１７）を形成し、ネッキング工程（Ｓ６）は、円筒状部（８Ｂ）を上側とし且つ半傘状部（９Ｂ）を下側としたときに、円筒状部（８Ｂ）の軸方向で円弧面（１７）よりも上側の部分を絞り加工する形態（例えば、図８等参照）が挙げられる。この場合、例えば、上記中空エンジンバルブ（１）は、中空孔（４）の最大外径（Ｄ１’）が鍛造工程（Ｓ３）で得られる中間部品（７Ｃ）の円筒状部（８Ｂ）の開口の内径（Ｄ２）と同じであることができる。
　なお、上記同じとは、略同じであることを意図しており、±５％程度の相違も含むものとする。 As a method of manufacturing the hollow engine valve according to the present embodiment, for example, the forging step (S3) includes the step of forming an arc surface (17) on the bottom end side of the inner peripheral surface of the cylindrical portion (8B) of the intermediate part (7C). Is formed, and the necking step (S6) includes, when the cylindrical portion (8B) is on the upper side and the semi-umbrella-shaped portion (9B) is on the lower side, an arc surface (17) in the axial direction of the cylindrical portion (8B). ) Is drawn (for example, see FIG. 8 and the like). In this case, for example, in the hollow engine valve (1), the opening of the cylindrical portion (8B) of the intermediate part (7C) in which the maximum outer diameter (D1 ′) of the hollow hole (4) is obtained in the forging step (S3). Can be the same as the inner diameter (D2).
The same is intended to be substantially the same, and includes a difference of about ± 5%.
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、上記スピニング工程（Ｓ５、Ｓ５’）は、加工ローラ（３２、１３２）を用いて中間部品（７Ｃ）の円筒状部（８Ｂ）をスピニング加工し、加工ローラ（３２、１３２）は、加工ローラ（３２、１３２）を挟んで加工ローラの軸方向に沿って配置される前後の軸受（３４、１３４）を介して支持部材（３５、１３５）に回転自在に支持されている形態（例えば、図６及び図１４等参照）が挙げられる。 As a method for manufacturing the hollow engine valve according to the present embodiment, for example, in the spinning step (S5, S5 ′), the cylindrical part (8B) of the intermediate part (7C) is formed using the processing rollers (32, 132). The spinning processing rollers (32, 132) support the support members (35, 132) via front and rear bearings (34, 134) disposed along the axial direction of the processing rollers across the processing rollers (32, 132). 135) (for example, see FIGS. 6 and 14).
　本実施形態に係る中空エンジンバルブの製造方法としては、例えば、中実円柱状の素材（６）を鍛造加工して、杯状拡径部（８Ａ）及び該杯状拡径部の縮径する軸端側に連なる円柱状部（９Ａ）を備える中間部品（７Ａ）を得る第１鍛造工程（Ｓ１）と、杯状拡径部（８Ａ）をしごき加工により円筒状部（８Ｂ）とするしごき工程（Ｓ２）と、を備え、上記鍛造工程は、円柱状部（９Ａ）を鍛造加工により半傘状部（９Ｂ）とする第２鍛造工程（Ｓ３）である形態（例えば、図１～図３等参照）が挙げられる。 As a method of manufacturing the hollow engine valve according to the present embodiment, for example, a solid cylindrical material (6) is forged to reduce the diameter of the cup-shaped enlarged portion (8A) and the cup-shaped enlarged portion. A first forging step (S1) for obtaining an intermediate part (7A) having a cylindrical part (9A) connected to the shaft end side, and ironing the cup-shaped enlarged part (8A) into a cylindrical part (8B) by ironing. Step (S2), wherein the forging step is a second forging step (S3) in which the columnar portion (9A) is forged into a semi-umbrella-shaped portion (9B) (for example, FIG. 1 to FIG. 1). 3 etc.).
　なお、上記実施形態で記載した各構成の括弧内の符号は、後述する実施例に記載の具体的構成との対応関係を示すものである。 In addition, reference numerals in parentheses of each configuration described in the above embodiment indicate a correspondence relationship with a specific configuration described in an example described later.
　以下、図面を用いて実施例により本発明を具体的に説明する。 Hereinafter, the present invention will be described in detail with reference to the drawings using examples.
（１）中空エンジンバルブの構成
　本実施例に係る中空エンジンバルブ１は、図３（ｃ）に示すように、軸部２及び該軸部２の軸端側に連なる傘状部３を備えている。これら軸部２及び傘状部３にわたって中空孔４が形成されている。この中空孔４の最大外径Ｄ１は、後述の鍛造工程Ｓ３で得られる中間部品７Ｃの円筒状部８Ｂの開口の内径Ｄ２（図３（ａ）参照）より僅かに小さな値とされている。さらに、中空エンジンバルブ１は、中空孔４を形成する内面の表面粗さＲａが約４．０とされている（図９参照）。 (1) Configuration of Hollow Engine Valve The hollow engine valve 1 according to the present embodiment includes a shaft portion 2 and an umbrella-shaped portion 3 connected to the shaft end of the shaft portion 2 as shown in FIG. I have. A hollow hole 4 is formed over the shaft portion 2 and the umbrella-shaped portion 3. The maximum outer diameter D1 of the hollow hole 4 is a value slightly smaller than the inner diameter D2 (see FIG. 3A) of the opening of the cylindrical portion 8B of the intermediate part 7C obtained in the forging step S3 described below. Further, the hollow engine valve 1 has an inner surface forming the hollow hole 4 with a surface roughness Ra of about 4.0 (see FIG. 9).
（２）中空エンジンバルブの製造方法
　本実施例に係る中空エンジンバルブの製造方法は、図１に示すように、第１鍛造工程Ｓ１、しごき工程Ｓ２、第２鍛造工程Ｓ３、熱処理工程Ｓ４、スピニング工程Ｓ５及びネッキング工程Ｓ６を備えている。 (2) Manufacturing Method of Hollow Engine Valve As shown in FIG. 1, the manufacturing method of the hollow engine valve according to the present embodiment includes a first forging step S1, an ironing step S2, a second forging step S3, a heat treatment step S4, and spinning. Step S5 and necking step S6 are provided.
　上記第１鍛造工程Ｓ１は、図２（ａ）（ｂ）に示すように、ニッケル基超合金製で中実円柱状の素材６を熱間鍛造加工して中間部品７Ａを得る工程である。この中間部品７Ａは、杯状拡径部８Ａと、杯状拡径部８Ａの縮径する軸端側に連なる円柱状部９Ａと、を備えている。さらに、第１鍛造工程Ｓ１では、杯状拡径部８Ａの内壁を形成するための凸状部１１ａを有する金型１１と、素材６を保持するとともに杯状拡径部８Ａの外壁を形成するための凹状部１２ａを有する金型１２と、が用いられる。 2) The first forging step S1 is a step of hot-forging a solid cylindrical material 6 made of a nickel-based superalloy to obtain an intermediate part 7A, as shown in FIGS. 2 (a) and 2 (b). The intermediate part 7A includes a cup-shaped enlarged-diameter portion 8A and a columnar portion 9A connected to the shaft end side of the cup-shaped enlarged-diameter portion 8A whose diameter is reduced. Further, in the first forging step S1, a mold 11 having a convex portion 11a for forming the inner wall of the cup-shaped enlarged-diameter portion 8A and the outer wall of the cup-shaped enlarged-diameter portion 8A while holding the raw material 6 are formed. And a mold 12 having a concave portion 12a.
　上記しごき工程Ｓ２は、図２（ｂ）（ｃ）に示すように、主に、中間部品７Ａの杯状拡径部８Ａを冷間しごき加工により円筒状部８Ｂとして中間部品７Ｂを得る工程である。この円筒状部８Ｂの外径は、円柱状部９Ａの外径と略同じとされている。さらに、しごき工程Ｓ２では、杯状拡径部８Ａをしごくための貫通孔１４ａが形成された金型１４と、円柱状部９Ａを押圧するための突起部１５ａを備える金型１５と、が用いられる。 The ironing step S2 is, as shown in FIGS. 2B and 2C, mainly a step of obtaining the intermediate part 7B as the cylindrical part 8B by cold ironing the cup-shaped enlarged diameter part 8A of the intermediate part 7A. is there. The outer diameter of the cylindrical portion 8B is substantially the same as the outer diameter of the columnar portion 9A. Further, in the ironing step S2, a mold 14 having a through hole 14a for ironing the cup-shaped enlarged diameter portion 8A and a mold 15 having a protrusion 15a for pressing the columnar portion 9A are used. Can be
　上記第２鍛造工程Ｓ３は、図２（ｃ）及び図３（ａ）に示すように、主に、中間部品７Ｂの円柱状部９Ａを熱間鍛造加工して傘状部３の半完成品である半傘状部９Ｂとして中間部品７Ｃを得る工程である。すなわち、第２鍛造工程Ｓ３で得られる中間部品７Ｃは、円筒状部８Ｂと、円筒状部８Ｂの軸端側に連なる半傘状部９Ｂと、を備えている。この円筒状部８Ｂの内周面の底端側には、円弧面１７が形成されている。さらに、第２鍛造工程Ｓ３では、円柱状部９Ａの底面を押圧するための凸状部１８ａを備える金型１８と、円柱状部９Ａ及び円筒状部８Ｂの外周側を保持する貫通孔１９ａが形成された金型１９と、貫通孔１９ａに挿入されて円筒状部８Ｂの底端側に当接するピン２０と、が用いられる。
　なお、上記第２鍛造工程Ｓ３で得られる中間部品７Ｃの円筒状部８Ｂの肉厚ｔは、約２ｍｍとされている。 In the second forging step S3, as shown in FIGS. 2C and 3A, the semi-finished product of the umbrella-shaped part 3 is mainly formed by hot forging the cylindrical part 9A of the intermediate part 7B. This is the step of obtaining the intermediate part 7C as the semi-umbrella-shaped part 9B. That is, the intermediate component 7C obtained in the second forging step S3 includes a cylindrical portion 8B and a semi-umbrella-shaped portion 9B connected to the shaft end of the cylindrical portion 8B. An arc surface 17 is formed on the bottom end side of the inner peripheral surface of the cylindrical portion 8B. Further, in the second forging step S3, the mold 18 having the convex portion 18a for pressing the bottom surface of the columnar portion 9A and the through hole 19a holding the outer peripheral side of the columnar portion 9A and the cylindrical portion 8B are formed. The formed mold 19 and a pin 20 inserted into the through hole 19a and abutting on the bottom end side of the cylindrical portion 8B are used.
The thickness t of the cylindrical portion 8B of the intermediate part 7C obtained in the second forging step S3 is about 2 mm.
　上記熱処理工程Ｓ４は、中間部品７Ｃを軟化させるために円筒状部８Ｂの肉厚ｔに応じて決められる加熱保持時間ｔ２で固溶化熱処理する工程である。この熱処理工程Ｓ４では、図４に示すように、中間部品７Ｃが所定の加熱温度Ｔ１（例えば、１０５０℃）に加熱保持された後に水冷される。具体的に、常温Ｔ２（例えば、２０℃）の中間部品７Ｃは、所定の昇温時間ｔ１（例えば、５分）で加熱温度Ｔ１まで昇温され、その加熱温度Ｔ１に所定の加熱保持時間ｔ２（例えば、１０分）の間保持される。その後、中間部品７Ｃは、所定の冷却時間ｔ３（例えば、１０秒）で常温Ｔ２まで急冷される。なお、上記加熱保持時間ｔ２は、中間部品７Ｃの円筒状部８Ｂの肉厚ｔの１ｍｍ当りに対して約５分となる値とされている。 熱処理 The heat treatment step S4 is a step of performing a solution heat treatment for a heating holding time t2 determined according to the wall thickness t of the cylindrical portion 8B in order to soften the intermediate part 7C. In the heat treatment step S4, as shown in FIG. 4, the intermediate component 7C is heated and held at a predetermined heating temperature T1 (for example, 1050 ° C.) and then water-cooled. Specifically, the intermediate component 7C at the normal temperature T2 (for example, 20 ° C.) is heated up to the heating temperature T1 in a predetermined heating time t1 (for example, 5 minutes), and is heated to the heating temperature T1 for a predetermined heating holding time t2. (Eg, 10 minutes). Thereafter, the intermediate component 7C is rapidly cooled to the normal temperature T2 for a predetermined cooling time t3 (for example, 10 seconds). The heating holding time t2 is set to a value that is about 5 minutes per 1 mm of the thickness t of the cylindrical portion 8B of the intermediate part 7C.
　上記水冷では、図５に示すように、容器２２内に貯留される冷却水２３（例えば、水道水等）が用いられる。この容器２２内には、ポンプ２４に接続されて水の噴射可能なノズル２５が配置されている。このノズル２５は、水の噴射により冷却水２３を攪拌するように配置されている。よって、容器２２内に多数（例えば、２０～３０個）の中間部品７Ｃを投入しても、冷却水２３の水温は２０～３０℃に保たれる。 水 In the water cooling, as shown in FIG. 5, cooling water 23 (for example, tap water) stored in a container 22 is used. A nozzle 25 connected to a pump 24 and capable of jetting water is arranged in the container 22. The nozzle 25 is arranged so as to stir the cooling water 23 by spraying water. Therefore, even if a large number (for example, 20 to 30) of the intermediate components 7C are put into the container 22, the temperature of the cooling water 23 is maintained at 20 to 30 ° C.
　上記スピニング工程Ｓ５は、図３（ａ）（ｂ）に示すように、熱処理された中間部品７Ｃの円筒状部８Ｂを冷間スピニング加工により軸方向に延伸して薄肉化して中間部品７Ｄを得る工程である。このスピニング工程Ｓ５では、図６に示すように、半傘状部９Ｂを把持して中間部品７Ｃを軸回りに回転させるチャック機構３１と、その外周面が円筒状部８Ｂの外周面に押し当てられる加工ローラ３２と、が用いられる。この加工ローラ３２の軸方向に延びる支持軸３３は、加工ローラ３２の両表面側のそれぞれで軸受３４を介して支持部材３５に回転自在に支持されている。言い替えると、加工ローラ３２は、該加工ローラ３２を挟んで加工ローラ３２の軸方向に沿って配置される前後の軸受３４を介して支持部材３５に回転自在に支持されている。この支持部材３５は、図示しない移動機構により、円筒状部８Ｂの径方向及び軸方向に移動可能とされている。なお、上記加工ローラ３２は、１つが用いられてもよいし、複数が用いられてもよい。 In the spinning step S5, as shown in FIGS. 3A and 3B, the cylindrical part 8B of the heat-treated intermediate part 7C is axially stretched by cold spinning to make the intermediate part 7D thin. It is a process. In the spinning step S5, as shown in FIG. 6, a chuck mechanism 31 for gripping the semi-umbrella-shaped portion 9B and rotating the intermediate part 7C around the axis, and pressing the outer peripheral surface against the outer peripheral surface of the cylindrical portion 8B. Processing roller 32 to be used. A support shaft 33 extending in the axial direction of the processing roller 32 is rotatably supported by a support member 35 via bearings 34 on both surface sides of the processing roller 32. In other words, the processing roller 32 is rotatably supported by the support member 35 via the front and rear bearings 34 disposed along the axial direction of the processing roller 32 with the processing roller 32 interposed therebetween. The support member 35 can be moved in the radial direction and the axial direction of the cylindrical portion 8B by a moving mechanism (not shown). Note that one or a plurality of the processing rollers 32 may be used.
　上記スピニング工程Ｓ５では、中間部品７Ｃの円筒状部８Ｂの内側に保持ピン３７が挿入されるが、保持ピン３７は、その先端が円筒状部８Ｂの底端側に当接しているのみで、円筒状部８Ｂの内周面には当接していない。すなわち、スピニング加工Ｓ５では、中間部品７Ｃの円筒状部８Ｂの内周面にはツールが何ら当接していない。 In the spinning step S5, the holding pin 37 is inserted inside the cylindrical portion 8B of the intermediate component 7C. However, the holding pin 37 has its tip only in contact with the bottom end side of the cylindrical portion 8B. It does not contact the inner peripheral surface of the cylindrical portion 8B. That is, in the spinning process S5, no tool is in contact with the inner peripheral surface of the cylindrical portion 8B of the intermediate component 7C.
　ここで、第２鍛造工程Ｓ３で得られる中間部品７Ｃの円筒状部８Ｂの肉厚に不揃いが生じることがあるが、その場合であっても、スピニング加工後の円筒状部８Ｂでは肉厚の不揃いが解消される。これに対して、スピニング加工の代わりにスウェージング加工を採用した場合、円筒状部８Ｂの肉厚の不揃いを解消し難い。 Here, the thickness of the cylindrical portion 8B of the intermediate part 7C obtained in the second forging step S3 may be uneven, but even in such a case, the thickness of the cylindrical portion 8B after the spinning process is reduced. The irregularities are eliminated. On the other hand, when swaging is employed instead of spinning, it is difficult to eliminate irregularities in the thickness of the cylindrical portion 8B.
　上記ネッキング工程Ｓ６は、図３（ｂ）（ｃ）に示すように、軸方向に延伸された円筒状部８Ｂを複数段階（例えば、９段階）の冷間絞り加工により徐々に縮径することで、軸部２及び傘状部３を形成する工程（即ち、中空エンジンバルブ１を得る工程）である。具体的に、円筒状部８Ｂの底端側以外の縮径された部分で軸部２が形成されるとともに、円筒状部８Ｂの底端側の縮径された部分と半傘状部９Ｂとで傘状部３が形成される。このネッキング工程Ｓ６では、中間部品７Ｄの半傘状部９Ｂを保持する金型３８と、円筒状部８Ｂを絞り加工するための成形孔３９ａを有する金型３９と、が用いられる。この金型３９としては、複数段階の絞り加工に応じて成形孔３９ａの穴径等が異なる複数種のものが使用される。 In the necking step S6, as shown in FIGS. 3 (b) and 3 (c), the cylindrical portion 8B extended in the axial direction is gradually reduced in diameter by a plurality of stages (for example, nine stages) of cold drawing. This is the step of forming the shaft portion 2 and the umbrella-shaped portion 3 (that is, the step of obtaining the hollow engine valve 1). Specifically, the shaft portion 2 is formed at a reduced diameter portion other than the bottom end side of the cylindrical portion 8B, and the reduced diameter portion at the bottom end side of the cylindrical portion 8B and the semi-umbrella-shaped portion 9B Thus, an umbrella-shaped portion 3 is formed. In the necking step S6, a mold 38 for holding the semi-umbrella-shaped portion 9B of the intermediate part 7D and a mold 39 having a forming hole 39a for drawing the cylindrical portion 8B are used. As the mold 39, a plurality of types having different hole diameters of the forming holes 39a according to a plurality of stages of drawing are used.
　上記ネッキング工程Ｓ６では、図７に示すように、中間部品７Ｄの円筒状部８Ｂの軸方向で円弧面１７を含む部分が絞り加工される。具体的に、最終段階（例えば、９段階目）の絞り加工の型締め時において、金型３９の下端面は、絞り加工前の中間部品７Ｄの円筒状部８Ｂの円弧面１７の上端（図７中に一点鎖線で示す高さ。）より下方に位置している。 In the necking step S6, as shown in FIG. 7, a portion including the arc surface 17 in the axial direction of the cylindrical portion 8B of the intermediate part 7D is drawn. Specifically, at the time of the final stage (for example, the ninth stage) of the die clamping in the drawing, the lower end surface of the mold 39 is at the upper end of the circular arc surface 17 of the cylindrical portion 8B of the intermediate part 7D before the drawing (FIG. 7 is indicated by an alternate long and short dash line.).
（３）実施例の効果
　本実施例の中空エンジンバルブの製造方法によると、鍛造加工により、円筒状部８Ｂ及び該円筒状部８Ｂの軸端側に連なる半傘状部９Ｂを備える中間部品７Ｃを得る鍛造工程Ｓ３と、中間部品７Ｃを軟化させるために円筒状部８Ｂの肉厚ｔに応じて決められる加熱保持時間ｔ２で熱処理する熱処理工程Ｓ４と、熱処理された中間部品７Ｃの円筒状部８Ｂをスピニング加工により軸方向に延伸するスピニング工程Ｓ５と、軸方向に延伸された円筒状部８Ｂを絞り加工により縮径することで、軸部２及び傘状部３を形成するネッキング工程Ｓ６と、を備える。このように、鍛造加工により得られた中間部品７Ｃを熱処理して軟化させることで、スピニング加工時及び絞り加工時に中間部品７Ｃの円筒状部８Ｂが伸び易くなるため、スピニング加工及び絞り加工の加工性に優れる。その結果、中空エンジンバルブ１の中空孔４を形成する内面での表面肌荒れの発生が抑制されて表面状態が良好となる。よって、中空エンジンバルブ１の強度の低下が抑制される。さらに、中空エンジンバルブ１の中空孔４内に冷却用の金属ナトリウムを入れる場合には、中空孔４内で金属ナトリウムが円滑に流動して効果的に冷却機能を発揮する。さらに、絞り加工の加工性に優れるため、傘状部３の中空孔４の外周側の潰れが抑制されるように、絞り加工の型締め時の金型３９の高さ位置を容易に調整できる。その結果、中空エンジンバルブ１の中空孔４の容積を大きくすることができる。 (3) Effects of Embodiment According to the method of manufacturing the hollow engine valve of the embodiment, the intermediate component 7C including the cylindrical portion 8B and the semi-umbrella-shaped portion 9B connected to the shaft end side of the cylindrical portion 8B by forging. , A heat treatment step S4 of performing a heat treatment for a heating holding time t2 determined according to the thickness t of the cylindrical portion 8B to soften the intermediate component 7C, and a cylindrical portion of the heat treated intermediate component 7C. A spinning step S5 for axially extending 8B by spinning, and a necking step S6 for forming the axial part 2 and the umbrella-shaped part 3 by reducing the diameter of the cylindrical part 8B extended in the axial direction by drawing. , Is provided. In this way, by heat-treating and softening the intermediate part 7C obtained by forging, the cylindrical part 8B of the intermediate part 7C is easily elongated at the time of spinning and drawing. Excellent in nature. As a result, the occurrence of surface roughening on the inner surface forming the hollow hole 4 of the hollow engine valve 1 is suppressed, and the surface condition is improved. Therefore, a decrease in the strength of the hollow engine valve 1 is suppressed. Further, when metal sodium for cooling is put in the hollow hole 4 of the hollow engine valve 1, the metal sodium flows smoothly in the hollow hole 4 and effectively exerts a cooling function. Furthermore, since the drawing processability is excellent, the height position of the mold 39 at the time of the drawing die clamping can be easily adjusted so that the outer peripheral side of the hollow hole 4 of the umbrella-shaped portion 3 is suppressed. . As a result, the volume of the hollow hole 4 of the hollow engine valve 1 can be increased.
　また、本実施例では、中間部品７Ｃは、ニッケル基超合金で形成されており、熱処理工程Ｓ４は、中間部品７Ｃを１０５０℃に加熱保持した後に水冷する。これにより、中間部品７Ｃを固溶化熱処理して効果的に軟化させることができる。 Also, in the present embodiment, the intermediate component 7C is formed of a nickel-based superalloy, and in the heat treatment step S4, the intermediate component 7C is heated and held at 1050 ° C. and then water-cooled. Thereby, the intermediate part 7C can be effectively softened by solution heat treatment.
　また、本実施例では、熱処理工程Ｓ４は、加熱された中間部品７Ｃを円筒状部８Ｂの肉厚ｔ（具体的に、２ｍｍ）の１ｍｍ当りに対して５分となる加熱保持時間ｔ２（具体的に、１０分）で保持する。これにより、中間部品７Ｃの加熱保持時間ｔ２を比較的短くでき、熱処理後の中間部品７Ｃの表面での酸化膜の発生を低減できる。 Further, in the present embodiment, the heat treatment step S4 is a heating holding time t2 (specifically, 5 minutes per 1 mm of the thickness t (specifically, 2 mm) of the cylindrical portion 8B). (10 minutes). Thereby, the heating holding time t2 of the intermediate component 7C can be relatively shortened, and the generation of an oxide film on the surface of the intermediate component 7C after the heat treatment can be reduced.
　また、本実施例では、熱処理工程Ｓ４は、中間部品７Ｃを、容器２２内で攪拌される冷却水２３中に投入して水冷する。これにより、冷却水２３の温度上昇が抑えられるため、熱処理工程Ｓ４で中間部品７Ｃを効果的に急冷できる。特に、本実施例では、冷却水２３の水温は、２０～３０℃であるので、熱処理工程Ｓ４で中間部品７Ｃを効果的に急冷できる。 In the present embodiment, in the heat treatment step S4, the intermediate component 7C is put into cooling water 23 stirred in the container 22 and water-cooled. Thereby, the temperature rise of the cooling water 23 is suppressed, so that the intermediate component 7C can be rapidly cooled in the heat treatment step S4 effectively. In particular, in the present embodiment, since the water temperature of the cooling water 23 is 20 to 30 ° C., the intermediate component 7C can be rapidly cooled effectively in the heat treatment step S4.
　また、本実施例では、中空エンジンバルブ１は、中空孔４を形成する内面の表面粗さＲａが４．０である。これにより、中空エンジンバルブ１の中空孔４を形成する内面の表面状態が極めて良好である。 In addition, in this embodiment, the hollow engine valve 1 has an inner surface forming the hollow hole 4 with a surface roughness Ra of 4.0. Thereby, the surface condition of the inner surface forming the hollow hole 4 of the hollow engine valve 1 is extremely good.
　さらに、本実施例では、スピニング工程Ｓ５は、加工ローラ３２を用いて中間部品７Ｃの円筒状部８Ｂをスピニング加工し、加工ローラ３２は、加工ローラ３２を挟んで加工ローラ３２の軸方向に沿って配置される前後の軸受３４を介して支持部材３５に回転自在に支持されている。これにより、加工ローラ３２の倒れ込みが抑制されるため、中間部品７Ｃの円筒状部８Ｂが効果的にスピニング加工される。 Further, in the present embodiment, in the spinning step S5, the cylindrical portion 8B of the intermediate part 7C is subjected to spinning using the processing roller 32, and the processing roller 32 is disposed along the axial direction of the processing roller 32 with the processing roller 32 interposed therebetween. It is rotatably supported by a support member 35 via front and rear bearings 34 which are arranged in front. Thereby, the falling of the processing roller 32 is suppressed, so that the cylindrical portion 8B of the intermediate part 7C is effectively spinned.
　さらに、本実施例では、中実円柱状の素材６を鍛造加工して、杯状拡径部８Ａ及び該杯状拡径部８Ａの縮径する軸端側に連なる円柱状部９Ａを備える中間部品７Ａを得る第１鍛造工程Ｓ１と、杯状拡径部８Ａをしごき加工して円筒状部８Ｂとするしごき工程Ｓ２と、円柱状部９Ａを鍛造加工して半傘状部９Ｂとする第２鍛造工程Ｓ３と、を備える。これにより、比較的小さな加圧力で比較的肉厚の薄い円筒状部８Ｂを容易に形成できる。 Further, in this embodiment, a solid cylindrical material 6 is forged, and an intermediate portion having a cup-shaped enlarged portion 8A and a columnar portion 9A connected to a shaft end side of the cup-shaped enlarged portion 8A whose diameter is reduced. A first forging step S1 for obtaining the part 7A, an ironing step S2 for ironing the cup-shaped enlarged-diameter portion 8A to form a cylindrical portion 8B, and a forging process for the columnar portion 9A to form a semi-umbrella portion 9B. 2 forging step S3. This makes it possible to easily form the relatively thin cylindrical portion 8B with a relatively small pressing force.
（４）実験例１～１９及び比較例について
　次に、図１１～図１３に基づいて、実験例１～１９及び比較例に係る中空エンジンバルブの製造方法の試験結果について説明する。これら実験例１～１９では、上述の実施例の中空エンジンバルブの製造方法と同様にして、第１鍛造工程Ｓ１、しごき工程Ｓ２、第２鍛造工程Ｓ３、熱処理工程Ｓ４、スピニング工程Ｓ５及びネッキング工程Ｓ６を経て中空エンジンバルブを製造した。一方、比較例では、上述の各工程Ｓ１～Ｓ６のうちで熱処理工程Ｓ４を省略して中空エンジンバルブを製造した。そして、実験例１～１９及び比較例の各製法で得られた中空エンジンバルの表面状態を確認するとともに、スピニング加工の加工性を確認して、総合評価を下した。 (4) Experimental Examples 1 to 19 and Comparative Example Next, test results of the method of manufacturing the hollow engine valve according to Experimental Examples 1 to 19 and the comparative example will be described with reference to FIGS. In these experimental examples 1 to 19, the first forging step S1, the ironing step S2, the second forging step S3, the heat treatment step S4, the spinning step S5, and the necking step were performed in the same manner as in the method of manufacturing the hollow engine valve of the above-described embodiment. Through S6, a hollow engine valve was manufactured. On the other hand, in the comparative example, a hollow engine valve was manufactured by omitting the heat treatment step S4 among the above steps S1 to S6. Then, the surface condition of the hollow engine bal obtained by each of the production methods of Experimental Examples 1 to 19 and Comparative Example was confirmed, and the workability of spinning was confirmed, and a comprehensive evaluation was made.
　ここで、実験例１～７では、ニッケル含有率が約５０％であるニッケル基超合金製の素材を用い、実験例８～１３では、ニッケル含有率が約８０％であるニッケル基超合金製の素材を用い、実験例１４～１９及び比較例では、ニッケル含有率が約３０％であるニッケル基超合金製の素材を用いた。また、実験例１～１９の熱処理工程では、加熱温度、加熱保持時間、冷却方法及び処理量等を変更した。特に、実験例１～１７では、攪拌されない冷却水中に中間部品を投入して水冷し、実験例１８及び１９では、攪拌中の冷却水中に中間部品を投入して水冷した。さらに、実験例１～１６では、１個の中間部品を冷却水中に投入して水冷し、実験例１７～１９では、１０～２０個の中間部品を冷却水中に投入して水冷した。 Here, in Experimental Examples 1 to 7, a nickel-based superalloy material having a nickel content of about 50% was used, and in Experimental Examples 8 to 13, a nickel-based superalloy material having a nickel content of about 80% was used. In Experimental Examples 14 to 19 and Comparative Example, a material made of a nickel-based superalloy having a nickel content of about 30% was used. In the heat treatment steps of Experimental Examples 1 to 19, the heating temperature, the heating holding time, the cooling method, the processing amount, and the like were changed. In particular, in Experimental Examples 1 to 17, the intermediate components were put into the unstirred cooling water and water-cooled, and in Experimental Examples 18 and 19, the intermediate components were put into the stirring cooling water and water-cooled. Further, in Experimental Examples 1 to 16, one intermediate component was put in cooling water and cooled with water, and in Experimental Examples 17 to 19, 10 to 20 intermediate components were charged in cooling water and cooled with water.
　その結果、比較例の製法で得られた中空エンジンバルブでは、中空孔を形成する内面に顕著な肌荒れが発生し、その表面粗さＲａが約２２．０であった（図１０参照）。さらに、スピニング加工での材料の伸びが悪く、加工性が極めて低かった。 As a result, in the hollow engine valve obtained by the manufacturing method of the comparative example, remarkable roughening occurred on the inner surface forming the hollow hole, and the surface roughness Ra was about 22.0 (see FIG. 10). Furthermore, the elongation of the material during spinning was poor and the workability was extremely low.
　これに対して、実験例１、２、６、９及び１１の製法で得られた中空エンジンバルブでは、中空孔を形成する内面に少々の肌荒れが発生するが、比較例に比べて表面状態が良好であった。また、実験例３－５、７、８、１０及び１２－１９の製法で得られた中空エンジンバルブでは、中空孔を形成する内面に肌荒れが発生せず、表面状態が極めて良好であった。特に、実験例１９の製法で得られた中空エンジンバルブでは、中空孔を形成する内面での酸化膜の発生が少なかった。 On the other hand, in the hollow engine valve obtained by the manufacturing method of Experimental Examples 1, 2, 6, 9 and 11, a slight roughening occurs on the inner surface where the hollow hole is formed. It was good. In addition, the hollow engine valves obtained by the production methods of Experimental Examples 3-5, 7, 8, 10, and 12-19 did not have rough surfaces on the inner surface where the hollow holes were formed, and the surface condition was extremely good. In particular, in the hollow engine valve obtained by the production method of Experimental Example 19, the generation of an oxide film on the inner surface forming the hollow hole was small.
　また、実験例１－１５及び１７の製法では、スピニング加工での材料の伸びがやや悪かったが、比較例に比べて加工性が高かった。また、実験例１６、１８及び１９の製法では、スピニング加工での材料の伸びが良く、加工性が極めて高かった。 In the production methods of Experimental Examples 1-15 and 17, the elongation of the material during spinning was slightly poor, but the workability was higher than that of the comparative example. In the production methods of Experimental Examples 16, 18, and 19, the material elongation during spinning was good, and the workability was extremely high.
　ここで、実験例１８及び１９の製法では、多数の中間部品を一度に処理しても効果的に水冷された。これは、攪拌を伴う冷却水で冷却することで、冷却水の温度上昇が抑制されるためである。さらに、実験例１９の製法では、中空エンジンバルブの中空孔を形成する内面での酸化膜の発生が少なかった。これは、加熱保持時間ｔ２が１０分と極めて短いためである。この点から、鍛造工程Ｓ３で得られた中間部品７Ｃを円筒状部８Ｂの肉厚ｔの１ｍｍ当りに対して５分程度の加熱保持時間ｔ２で保持することで、スピニング加工に必要な成分組織の改質が得られると言える。 Here, in the production methods of Experimental Examples 18 and 19, even if a large number of intermediate parts were treated at one time, water was effectively cooled. This is because the temperature rise of the cooling water is suppressed by cooling with the cooling water accompanied by stirring. Furthermore, in the manufacturing method of Experimental Example 19, the generation of an oxide film on the inner surface forming the hollow hole of the hollow engine valve was small. This is because the heating holding time t2 is as short as 10 minutes. From this point, by holding the intermediate part 7C obtained in the forging step S3 for a heating holding time t2 of about 5 minutes per 1 mm of the wall thickness t of the cylindrical part 8B, the component structure necessary for spinning is performed. Can be said to be obtained.
＜他の形態のスピニング工程＞
　次に、他の形態のスピニング工程Ｓ５’について説明するが、上述のスピニング工程Ｓ５と略同じ構成の部位には同じ符号を付けて詳説を省略する。 <Another form of spinning process>
Next, a description will be given of a spinning step S5 'of another embodiment. Parts having substantially the same configuration as those of the above-described spinning step S5 are denoted by the same reference numerals, and detailed description thereof will be omitted.
（１）スピニング工程について
　上記スピニング工程Ｓ５’は、図３（ａ）（ｂ）に示すように、熱処理された中間部品７Ｃの円筒状部８Ｂを冷間スピニング加工により軸方向に延伸して薄肉化して中間部品７Ｄを得る工程である。このスピニング工程Ｓ５’では、図１４に示すように、半傘状部９Ｂを把持して中間部品７Ｃを軸回りに回転させるチャック機構１３１と、その外周円弧面１３２ａが円筒状部８Ｂの外周面に押し当てられる加工ローラ１３２と、が用いられる。この加工ローラ１３２は、その軸方向に延びる支持軸１３３（すなわち、支持部材１３５）に対して、加工ローラ１３２を挟んで加工ローラ１３２の軸方向に沿って配置される前後の軸受１３４（具体的に、スラスト軸受１３４）を介して回転自在に支持されている。この支持部材１３５は、図示しない移動機構により、円筒状部８Ｂの径方向及び軸方向に移動可能とされている。 (1) Spinning Step In the spinning step S5 ′, as shown in FIGS. 3A and 3B, the cylindrical part 8B of the heat-treated intermediate part 7C is stretched in the axial direction by cold spinning to obtain a thin wall. This is the step of obtaining the intermediate part 7D by the conversion. In the spinning step S5 ′, as shown in FIG. 14, a chuck mechanism 131 that grips the semi-umbrella-shaped portion 9B and rotates the intermediate component 7C around the axis, and the outer peripheral arc surface 132a of which is formed on the outer peripheral surface of the cylindrical portion 8B And a processing roller 132 pressed against the roller. The processing roller 132 has front and rear bearings 134 (specifically, front and rear) disposed along the axial direction of the processing roller 132 with the processing roller 132 interposed therebetween with respect to a support shaft 133 (that is, a support member 135) extending in the axial direction. And is rotatably supported via a thrust bearing 134). The support member 135 is movable in a radial direction and an axial direction of the cylindrical portion 8B by a moving mechanism (not shown).
　なお、上記加工ローラ１３２は、１つが用いられてもよいし、複数が用いられてもよい。また、図１４中の円筒状部８Ｂにおいて、中心線より上側の部分がスピニング加工前の肉厚（例えば、１．６５ｍｍ）を示し、中心線より下側の部分がスピニング加工後の肉厚（例えば、１．０ｍｍ）を示す。 Note that one or a plurality of the processing rollers 132 may be used. In the cylindrical portion 8B in FIG. 14, the portion above the center line indicates the thickness before spinning (for example, 1.65 mm), and the portion below the center line after spinning (for example, 1.65 mm). For example, 1.0 mm).
　上記スピニング加工Ｓ５’では、図１５に示すように、円筒状部８Ｂの外周面に加工ローラ１３２の外周円弧面１３２ａを所定の切込み量ｄで押し当てながら、加工ローラ１３２を円筒状部８Ｂの軸方向に沿う加工方向Ｐに移動させてこれを繰り返すことで、円筒状部８Ｂが軸方向に延伸される。なお、上記スピニング加工Ｓ５’における切込み量ｄ及び延伸させる方向Ｐへの移動回数等は特に問わない。また、スピニング加工Ｓ５’では、通常、スピニング加工時に切込み量ｄよりも小さな量の戻りが生じる。 In the spinning process S5 ′, as shown in FIG. 15, the processing roller 132 is pressed against the outer peripheral surface of the cylindrical portion 8B while pressing the outer circular arc surface 132a of the processing roller 132 at a predetermined cutting amount d. By moving in the processing direction P along the axial direction and repeating this, the cylindrical portion 8B is stretched in the axial direction. The cut amount d and the number of movements in the stretching direction P in the spinning process S5 'are not particularly limited. In the spinning process S5 ', an amount smaller than the cut amount d usually occurs during the spinning process.
　ここで、加工ローラ１３２の外周円弧面１３２ａの曲率半径Ｒは、スピニング加工前の円筒状部８Ｂの肉厚ｔの３～５倍の値とされている。そして、スピニング加工時に、円筒状部８Ｂの軸方向に沿う断面において、加工ローラ１３２の外周円弧面１３２ａが円筒状部８Ｂの外周面と接する円弧の一端ｐ１と他端ｐ２とを結ぶ直線Ｌ１は、円筒状部８Ｂの軸方向に対して５～７度の傾斜角度θ１で傾斜している。これにより、切込み量ｄの最大値と最小値を想定考慮して加工ローラ１３２の外周円弧面１３２ａの曲率半径Ｒを設定することとなるため、スピニング加工時に中間部品７Ｃの円筒状部８Ｂを効果的に延伸できる。 Here, the radius of curvature R of the outer circular arc surface 132a of the processing roller 132 is 3 to 5 times the thickness t of the cylindrical portion 8B before spinning. Then, at the time of spinning, in a cross section along the axial direction of the cylindrical portion 8B, a straight line L1 connecting one end p1 and the other end p2 of the arc where the outer circumferential arc surface 132a of the processing roller 132 contacts the outer circumferential surface of the cylindrical portion 8B is formed. Is inclined at an inclination angle θ1 of 5 to 7 degrees with respect to the axial direction of the cylindrical portion 8B. As a result, the radius of curvature R of the outer circular arc surface 132a of the processing roller 132 is set by assuming the maximum value and the minimum value of the cutting amount d, so that the cylindrical portion 8B of the intermediate part 7C is effectively used during spinning. Stretching is possible.
　なお、上記一端ｐ１は、通常、スピニング加工時に、円筒状部８Ｂの軸方向に沿う断面において、加工ローラ１３２の外周円弧面１３２ａの曲率半径Ｒの中心を通り且つ円筒状部８Ｂの軸心と直交する直線Ｌ２が円筒状部８Ｂの外周面と交差する点である。また、上記スピニング工程Ｓ５の加工ローラ３２の曲率半径Ｒ及び傾斜角度θ１として、スピニング工程Ｓ５’の加工ローラ１３２の曲率半径Ｒ及び傾斜角度θ１と同じ条件を採用している。 Note that the one end p1 usually passes through the center of the radius of curvature R of the outer circular arc surface 132a of the processing roller 132 in the cross section along the axial direction of the cylindrical portion 8B during spinning, and is in contact with the axis of the cylindrical portion 8B. This is a point where the orthogonal straight line L2 intersects the outer peripheral surface of the cylindrical portion 8B. The same conditions as the radius of curvature R and the inclination angle θ1 of the processing roller 132 in the spinning step S5 ′ are employed as the radius of curvature R and the inclination angle θ1 of the processing roller 32 in the spinning step S5.
（２）実験例２０～２７について
　次に、図１６に基づいて、実験例２０～２７に係るスピニング工程の試験結果について説明する。これら実験例２０～２７では、上述の第１鍛造工程Ｓ１、しごき工程Ｓ２、第２鍛造工程Ｓ３、熱処理工程Ｓ４（実験例１９）を経た中間部品７Ｃに対して、円筒状部８Ｂの肉厚ｔが１．６５ｍｍから１ｍｍとなるまで複数回のスピニング加工を行った。各実験例２０～２４では、円筒状部８Ｂに対する加工ローラ１３２の切込み量ｄを０．１５ｍｍとした。さらに、各実験例２５～２７では、円筒状部８Ｂに対する加工ローラ１３２の切込み量ｄを０．１ｍｍとした。そして、スピニング加工後の中間部品７Ｄの表面状態を確認し、その表面状態及びスピニング回数に基づいて評価を下した。 (2) Experimental Examples 20 to 27 Next, test results of the spinning step according to Experimental Examples 20 to 27 will be described with reference to FIG. In these Experimental Examples 20 to 27, the thickness of the cylindrical portion 8B was increased with respect to the intermediate part 7C that had undergone the first forging step S1, the ironing step S2, the second forging step S3, and the heat treatment step S4 (Experimental Example 19). A plurality of spinning processes were performed until t became 1.65 mm to 1 mm. In each of Experimental Examples 20 to 24, the cut amount d of the processing roller 132 with respect to the cylindrical portion 8B was set to 0.15 mm. Further, in each of Experimental Examples 25 to 27, the cut amount d of the processing roller 132 into the cylindrical portion 8B was set to 0.1 mm. Then, the surface state of the intermediate component 7D after the spinning was confirmed, and an evaluation was made based on the surface state and the number of times of spinning.
　なお、上記実験例２０～２７では、汎用のＮＣ旋盤を用いて、中間部品７Ｃの回転数を１２００ｒｐｍとし、加工ローラ１３２の送り速度を０．１３ｍｍ／ｓとした。 In the experimental examples 20 to 27, the rotation speed of the intermediate part 7C was set to 1200 rpm and the feed speed of the processing roller 132 was set to 0.13 mm / s using a general-purpose NC lathe.
　実験例２１～２３、２５及び２６では、その外周円弧面１３２ａの曲率半径Ｒがスピニング加工前の円筒状部８Ｂの肉厚ｔの３～５倍の値であり、直線Ｌ１が円筒状部８Ｂの軸方向に対して５～７度の傾斜角度θ１で傾斜する加工ローラ１３２を採用した。その結果、実験例２１～２３で得られた中間部品７Ｄの表面状態は滑らかで良く、スピニング回数が１０回であり加工性にも優れる。また、実験例２５及び２６で得られた中間部品７Ｄの表面状態は滑らかで良く、スピニング回数が１３回であり加工性にも優れる。 In Experimental Examples 21 to 23, 25 and 26, the radius of curvature R of the outer circular arc surface 132a is 3 to 5 times the thickness t of the cylindrical portion 8B before spinning, and the straight line L1 is the cylindrical portion 8B. The working roller 132 is inclined at an inclination angle θ1 of 5 to 7 degrees with respect to the axial direction. As a result, the surface condition of the intermediate part 7D obtained in Experimental Examples 21 to 23 is smooth and good, the number of spinning is 10 times, and the workability is excellent. Further, the surface condition of the intermediate part 7D obtained in Experimental Examples 25 and 26 is smooth and good, the number of spinning is 13 times, and the workability is excellent.
　一方、実験例２０では、その外周円弧面１３２ａの曲率半径Ｒがスピニング加工前の円筒状部８Ｂの肉厚ｔの約１．８倍の値であり、直線Ｌ１が円筒状部８Ｂの軸方向に対して９度の傾斜角度θ１で傾斜する加工ローラ１３２を採用した。その結果、実験例２０で得られた中間部品７Ｄの表面状態はやや荒れた肌を示したが、スピニング回数が１０回であり加工性に優れる。 On the other hand, in Experimental Example 20, the radius of curvature R of the outer circular arc surface 132a is about 1.8 times the thickness t of the cylindrical portion 8B before spinning, and the straight line L1 is in the axial direction of the cylindrical portion 8B. A processing roller 132 inclined at an inclination angle θ1 of 9 degrees is used. As a result, the surface condition of the intermediate part 7D obtained in Experimental Example 20 showed a slightly rough skin, but the number of spinning was 10 times, and the workability was excellent.
　また、実験例２４では、その外周円弧面１３２ａの曲率半径Ｒがスピニング加工前の円筒状部８Ｂの肉厚ｔの約６倍の値であり、直線Ｌ１が円筒状部８Ｂの軸方向に対して４．５度の傾斜角度θ１で傾斜する加工ローラ１３２を採用した。その結果、実験例２４で得られた中間部品７Ｄの表面状態は滑らかで良いが、スピニング回数が１６回であった。 In Experimental Example 24, the radius of curvature R of the outer circular arc surface 132a is a value approximately six times the thickness t of the cylindrical portion 8B before spinning, and the straight line L1 is aligned with the axial direction of the cylindrical portion 8B. The processing roller 132 is inclined at an inclination angle θ1 of 4.5 degrees. As a result, the surface state of the intermediate part 7D obtained in Experimental Example 24 was smooth and good, but the number of times of spinning was 16 times.
　さらに、実験例２７では、その外周円弧面１３２ａの曲率半径Ｒがスピニング加工前の円筒状部８Ｂの肉厚ｔの５倍の値であり、直線Ｌ１が円筒状部８Ｂの軸方向に対して４．５度の傾斜角度θ１で傾斜する加工ローラ１３２を採用した。その結果、実験例２７で得られた中間部品７Ｄの表面状態は滑らかで良いが、スピニング回数が２０回であった。 Further, in Experimental Example 27, the radius of curvature R of the outer circumferential arc surface 132a is a value five times the thickness t of the cylindrical portion 8B before spinning, and the straight line L1 is defined with respect to the axial direction of the cylindrical portion 8B. A processing roller 132 inclined at an inclination angle θ1 of 4.5 degrees was employed. As a result, although the surface state of the intermediate part 7D obtained in Experimental Example 27 was smooth and good, the number of times of spinning was 20 times.
　なお、本発明においては、上記実施例に限られず、目的、用途に応じて本発明の範囲内で種々変更した実施例とすることができる。すなわち、上記実施例では、熱間鍛造加工、冷間しごき加工、冷間スピニング加工、及び冷間絞り加工等を例示したが、これに限定されず、例えば、これら各加工は、熱間、温間、冷間加工のうちから適宜選択できる。さらに、これら各加工は、１回の加工であってもよいし、複数回の加工であってもよい。 The present invention is not limited to the above embodiments, but may be variously modified within the scope of the present invention according to purposes and applications. That is, in the above-described embodiment, hot forging, cold ironing, cold spinning, cold drawing, and the like are exemplified, but the invention is not limited thereto. And cold working. Further, each of these processes may be a single process or a plurality of processes.
　また、上記実施例では、オーステナイト系耐熱材料（具体的に、ニッケル基超合金）により形成される中間部品７Ｃを例示したが、これに限定されず、例えば、ＳＵＨ３、ＳＵＨ１１等のマルテンサイト系耐熱材料により形成される中間部品７Ｃとしてもよい。この場合、熱処理工程Ｓ４では、中間部品７Ｃの材料に適した熱処理が行われる。 In the above-described embodiment, the intermediate part 7C formed of an austenitic heat-resistant material (specifically, a nickel-based superalloy) is exemplified. However, the present invention is not limited thereto. The intermediate part 7C made of a material may be used. In this case, in the heat treatment step S4, heat treatment suitable for the material of the intermediate part 7C is performed.
　また、上記実施例では、鍛造加工により杯状拡径部８Ａを備える中間部品７Ａを形成し、その杯状拡径部８Ａをしごき加工により円筒状部８Ｂとして円筒状部８Ｂを備える中間部品７Ｂを得るようにしたが、これに限定されず、例えば、杯状拡径部８Ａを形成することなく、鍛造加工により円筒状部８Ｂを備える中間部品７Ｂを得るようにしてもよい。 In the above embodiment, the intermediate component 7A having the cup-shaped enlarged portion 8A is formed by forging, and the intermediate component 7B having the cylindrical portion 8B as the cylindrical portion 8B by ironing the cup-shaped enlarged portion 8A. However, the present invention is not limited to this. For example, the intermediate component 7B including the cylindrical portion 8B may be obtained by forging without forming the cup-shaped enlarged portion 8A.
　また、上記実施例では、ノズル２５の水の噴射により容器２２内で冷却水２３を攪拌するようにしたが、これに限定されず、例えば、攪拌羽根又は攪拌スクリュウの回転により容器２２内で冷却水２３を攪拌するようにしてもよい。さらに、例えば、容器２２に循環経路を接続し、容器２２に対して冷却水２３を循環させるようにしてもよい。この場合であっても、冷却水２３の温度上昇が抑えられるため、熱処理工程Ｓ４で中間部品７Ｃを効果的に急冷できる。 Further, in the above embodiment, the cooling water 23 is stirred in the container 22 by spraying the water from the nozzle 25. However, the present invention is not limited to this. For example, the cooling water 23 is cooled in the container 22 by rotating a stirring blade or a stirring screw. The water 23 may be stirred. Further, for example, a circulation path may be connected to the container 22 so that the cooling water 23 is circulated through the container 22. Even in this case, since the temperature rise of the cooling water 23 is suppressed, the intermediate part 7C can be rapidly cooled in the heat treatment step S4.
　また、上記実施例では、スピニング工程Ｓ５、Ｓ５’で、その外周円弧面１３２ａの曲率半径Ｒがスピニング加工前の円筒状部８Ｂの肉厚ｔの３～５倍の値である加工ローラ１３２を用いる形態を例示したが、これに限定されず、例えば、その外周円弧面１３２ａの曲率半径Ｒが、スピニング加工前の円筒状部８Ｂの肉厚ｔの３倍未満の値又は５倍を超える値である加工ローラ１３２を用いてもよい。 Further, in the above-described embodiment, in the spinning processes S5 and S5 ′, the processing roller 132 in which the radius of curvature R of the outer circular arc surface 132a is 3 to 5 times the thickness t of the cylindrical portion 8B before the spinning is performed. Although the form of use is illustrated, the present invention is not limited to this. For example, the radius of curvature R of the outer peripheral arc surface 132a is a value less than three times or more than five times the thickness t of the cylindrical portion 8B before spinning. May be used.
　また、上記実施例では、スピニング工程Ｓ５、Ｓ５’で、直線Ｌ１が円筒状部の軸方向に対して５～７度の傾斜角度θ１で傾斜する加工ローラ１３２を用いる形態を例示したが、これに限定されず、例えば、直線Ｌ１が、円筒状部８Ｂの軸方向に対して５度未満又は７度を超える傾斜角度θ１で傾斜する加工ローラ１３２を用いてもよい。 Further, in the above-described embodiment, in the spinning processes S5 and S5 ′, the form in which the processing roller 132 in which the straight line L1 is inclined at an inclination angle θ1 of 5 to 7 degrees with respect to the axial direction of the cylindrical portion is used is exemplified. For example, a processing roller 132 may be used in which the straight line L1 is inclined at an inclination angle θ1 of less than 5 degrees or more than 7 degrees with respect to the axial direction of the cylindrical portion 8B.
　また、上記実施例では、中間部品７Ｄの円筒状部８Ｂの軸方向で円弧面１７を含む部分を絞り加工するネッキング工程Ｓ６を例示したが、これに限定されず、例えば、図８に示すように、中間部品７Ｄの円筒状部８Ｂを上側とし且つ半傘状部９Ｂを下側としたきに、円筒状部８Ｂの軸方向で円弧面１７よりも上側の部分を絞り加工するネッキング加工Ｓ６としてもよい。この場合、絞り加工の型締め時において、金型３９の下端面は、絞り加工前の中間部品７Ｄの円筒状部８Ｂの円弧面１７の上端（図８中に一点鎖線で示す高さ。）より上方に位置している。これにより、中空エンジンバルブ１の中空孔４の最大外径Ｄ１’が鍛造工程Ｓ３で得られる中間部品７Ｄの円筒状部８Ｂの開口の内径Ｄ２（図３（ａ）参照）と同じにできる。その結果、中空エンジンバルブ１の中空孔４の容積を更に大きくできる。 Further, in the above-described embodiment, the necking step S6 in which the portion including the arc surface 17 is drawn in the axial direction of the cylindrical portion 8B of the intermediate part 7D is illustrated. However, the present invention is not limited to this. For example, as shown in FIG. Next, when the cylindrical portion 8B of the intermediate part 7D is set to the upper side and the semi-umbrella-shaped portion 9B is set to the lower side, the necking process S6 for drawing the portion above the arc surface 17 in the axial direction of the cylindrical portion 8B. It may be. In this case, the lower end surface of the mold 39 is closed at the upper end of the circular arc surface 17 of the cylindrical portion 8B of the intermediate part 7D before drawing (the height indicated by a dashed line in FIG. 8). It is located above. Thereby, the maximum outer diameter D1 'of the hollow hole 4 of the hollow engine valve 1 can be made the same as the inner diameter D2 of the opening of the cylindrical portion 8B of the intermediate part 7D obtained in the forging step S3 (see FIG. 3A). As a result, the volume of the hollow hole 4 of the hollow engine valve 1 can be further increased.
　さらに、上記実施例では、前後の軸受３４により両持ち支持された加工ローラ３２を例示したが、これに限定されず、例えば、片持ち支持された加工ローラ３２としてもよい。さらに、例えば、加工ローラ３２に替えて又は加えて、加工へらを用いるスピニング工程Ｓ５としてもよい。 Further, in the above-described embodiment, the processing roller 32 supported at both ends by the front and rear bearings 34 is exemplified. However, the present invention is not limited to this. For example, the processing roller 32 may be supported at one end. Furthermore, for example, instead of or in addition to the processing roller 32, a spinning step S5 using a processing spatula may be performed.
　本発明は、軽量で且つ耐熱性に優れた中空エンジンバルブを製造する技術として好適に利用される。 The present invention is suitably used as a technique for manufacturing a hollow engine valve that is lightweight and has excellent heat resistance.
　１；中空エンジンバルブ、２；軸部、３；傘状部、４；中空孔、７Ｃ；中間部品、８Ｂ；円筒状部、９Ｂ；半傘状部、１７；円弧面、２２；容器、２３；冷却水、３２，１３２；加工ローラ、３３；支持軸、３４，１３４；軸受、３５，１３５；支持部材、３９，１３９；金型、Ｓ３；第２鍛造工程、Ｓ４；熱処理工程、Ｓ５，Ｓ５’；スピニング工程、Ｓ６；ネッキング工程、Ｔ１；加熱温度、ｔ２；加熱保持時間。 DESCRIPTION OF SYMBOLS 1; Hollow engine valve, 2; Shaft part, 3; Umbrella part, 4; Hollow hole, 7C: Intermediate part, 8B; Cylindrical part, 9B; Semi-umbrella part, 17; Cooling water, 32, 132; processing roller, 33; support shaft, 34, 134; bearing, 35, 135; support member, 39, 139; mold, S3; second forging step, S4; S5 ': spinning step, S6: necking step, T1: heating temperature, t2: heating holding time.

Claims (9)

  1. 　軸部及び該軸部の軸端側に連なる傘状部を備え、前記軸部及び前記傘状部にわたって中空孔が形成された中空エンジンバルブの製造方法であって、
    　鍛造加工により、円筒状部及び該円筒状部の軸端側に連なる半傘状部を備える中間部品を得る鍛造工程と、
    　前記中間部品を軟化させるために前記円筒状部の肉厚に応じて決められる加熱保持時間で熱処理する熱処理工程と、
    　熱処理された前記中間部品の前記円筒状部をスピニング加工により軸方向に延伸するスピニング工程と、
    　軸方向に延伸された前記円筒状部を絞り加工により縮径することで、前記軸部及び前記傘状部を形成するネッキング工程と、を備えることを特徴とする中空エンジンバルブの製造方法。     A method for manufacturing a hollow engine valve, comprising: a shaft portion and an umbrella-shaped portion connected to a shaft end side of the shaft portion, wherein a hollow hole is formed over the shaft portion and the umbrella-shaped portion,
    By forging, a forging step of obtaining an intermediate part having a cylindrical portion and a semi-umbrella-shaped portion connected to the shaft end side of the cylindrical portion,
    A heat treatment step of performing a heat treatment for a heating holding time determined according to the thickness of the cylindrical portion to soften the intermediate part,
    A spinning step of extending the heat-treated intermediate part in the axial direction by spinning the cylindrical part,
    A necking step of forming the shaft portion and the umbrella-shaped portion by reducing the diameter of the cylindrical portion stretched in the axial direction by drawing. A method for manufacturing a hollow engine valve.
  2. 　前記中間部品は、オーステナイト系耐熱材料で形成されており、
    　前記熱処理工程は、前記中間部品を１０００～１１００℃に加熱保持した後に水冷する請求項１記載の中空エンジンバルブの製造方法。     The intermediate component is formed of an austenitic heat-resistant material,
    The method for manufacturing a hollow engine valve according to claim 1, wherein, in the heat treatment step, the intermediate component is heated and held at 1000 to 1100 ° C and then water-cooled.
  3. 　前記熱処理工程は、加熱された前記中間部品を前記円筒状部の肉厚の１ｍｍ当りに対して３～８分となる加熱保持時間で保持する請求項２記載の中空エンジンバルブの製造方法。 The method according to claim 2, wherein in the heat treatment step, the heated intermediate component is held for a heating holding time of 3 to 8 minutes per 1 mm of the thickness of the cylindrical portion.
  4. 　前記熱処理工程は、前記中間部品を、容器内で攪拌される冷却水中又は容器に対して循環される冷却水中に投入して水冷する請求項２又は３に記載の中空エンジンバルブの製造方法。 4. The method for manufacturing a hollow engine valve according to claim 2, wherein, in the heat treatment step, the intermediate component is put into cooling water stirred in a container or cooling water circulated in the container and water-cooled.
  5. 　前記冷却水の水温は、１５～３５℃である請求項４記載の中空エンジンバルブの製造方法。 方法 The method for manufacturing a hollow engine valve according to claim 4, wherein a temperature of the cooling water is 15 to 35 ° C.
  6. 　前記スピニング工程は、前記円筒状部の外周面に加工ローラの外周円弧面を所定の切込み量で押し当てながら、前記加工ローラを前記円筒状部に対して軸方向に移動させて前記円筒状部を軸方向に延伸し、
    　前記加工ローラの外周円弧面の曲率半径は、スピニング加工前の前記円筒状部の肉厚の３～５倍の値であり、
    　前記スピニング加工時に、前記円筒状部の軸方向に沿う断面において、前記加工ローラの外周円弧面が前記円筒状部の外周面と接する円弧の一端と他端とを結ぶ直線は、前記円筒状部の軸方向に対して５～７度の傾斜角度で傾斜している請求項１乃至５のいずれか一項に記載の中空エンジンバルブの製造方法。     The spinning step includes moving the processing roller in the axial direction with respect to the cylindrical portion while pressing an outer circular arc surface of the processing roller against the outer peripheral surface of the cylindrical portion by a predetermined cut amount. Is stretched in the axial direction,
    The radius of curvature of the outer circumferential arc surface of the processing roller is 3 to 5 times the thickness of the cylindrical portion before spinning,
    At the time of the spinning process, in a cross section along the axial direction of the cylindrical portion, a straight line connecting one end and the other end of an arc in which the outer circumferential surface of the processing roller is in contact with the outer circumferential surface of the cylindrical portion is the cylindrical portion. The method of manufacturing a hollow engine valve according to any one of claims 1 to 5, wherein the hollow engine valve is inclined at an inclination angle of 5 to 7 degrees with respect to the axial direction.
  7. 　前記中空エンジンバルブは、前記中空孔を形成する内面の表面粗さＲａが４．０～２２．０である請求項１乃至６のいずれか一項に記載の中空エンジンバルブの製造方法。 The method for manufacturing a hollow engine valve according to any one of claims 1 to 6, wherein the hollow engine valve has an inner surface forming the hollow hole having a surface roughness Ra of 4.0 to 22.0.
  8. 　前記鍛造工程は、前記中間部品の前記円筒状部の内周面の底端側に円弧面を形成し、
    　前記ネッキング工程は、前記円筒状部を上側とし且つ前記半傘状部を下側としたときに、前記円筒状部の軸方向で前記円弧面よりも上側の部分を絞り加工する請求項１乃至７のいずれか一項に記載の中空エンジンバルブの製造方法。     The forging step forms an arc surface on the bottom end side of the inner peripheral surface of the cylindrical portion of the intermediate part,
    The said necking process draws the part above the said circular-arc surface in the axial direction of the said cylindrical part, when the said cylindrical part is an upper side and the said semi-umbrella-shaped part is a lower side. A method for manufacturing a hollow engine valve according to any one of claims 7 to 13.
  9. 　前記スピニング工程は、加工ローラを用いて前記中間部品の前記円筒状部をスピニング加工し、
    　前記加工ローラは、該加工ローラを挟んで該加工ローラの軸方向に沿って配置される前後の軸受を介して支持部材に回転自在に支持されている請求項１乃至８のいずれか一項に記載の中空エンジンバルブの製造方法。     The spinning step, spinning the cylindrical portion of the intermediate component using a processing roller,
    9. The processing roller according to claim 1, wherein the processing roller is rotatably supported by a support member via front and rear bearings disposed along the axial direction of the processing roller with the processing roller interposed therebetween. 10. A method for manufacturing the hollow engine valve according to the above.
PCT/JP2019/024806 2018-06-28 2019-06-21 Method for manufacturing hollow engine valve WO2020004286A1 (en)

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