JPH1181932A - Method of forming intake valve for engine - Google Patents
Method of forming intake valve for engineInfo
- Publication number
- JPH1181932A JPH1181932A JP23873297A JP23873297A JPH1181932A JP H1181932 A JPH1181932 A JP H1181932A JP 23873297 A JP23873297 A JP 23873297A JP 23873297 A JP23873297 A JP 23873297A JP H1181932 A JPH1181932 A JP H1181932A
- Authority
- JP
- Japan
- Prior art keywords
- billet
- intake valve
- cross
- sto
- cold forging
- 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.)
- Pending
Links
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- Forging (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明はエンジン用吸気弁の
成形方法に関する。The present invention relates to a method for forming an intake valve for an engine.
【０００２】[0002]
【従来の技術】エンジン用吸気弁は、エンジン用排気弁
と同様に、燃焼室の高温ガスに晒されるため耐熱鋼を塑
性加工した弁を使用する。エンジン用吸気弁は、その特
性上、エンジン用排気弁ほど高温に晒されないので、エ
ンジン用排気弁に対して安価であるマルテンサイト系耐
熱鋼が好適である。そして、一般的にエンジン用吸気弁
の成形方法は、マルテンサイト系耐熱鋼の細径軸材の一
端をアプセット加工して熱間鍛造で傘部の成形するもの
である。2. Description of the Related Art Like an exhaust valve for an engine, an intake valve for an engine uses a valve obtained by plastically processing heat-resistant steel because it is exposed to high-temperature gas in a combustion chamber. Since the engine intake valve is not exposed to a high temperature as the engine exhaust valve due to its characteristics, martensitic heat-resistant steel which is inexpensive to the engine exhaust valve is preferable. In general, a method of forming an intake valve for an engine is to upset one end of a small-diameter shaft material of martensitic heat-resistant steel and form an umbrella portion by hot forging.
【０００３】[0003]
【発明が解決しようとする課題】熱間鍛造であれば、塑
性加工が容易である。しかし、熱間鍛造では例えば１０
００℃以上の高温でワークを加熱しなければならないの
で、その熱エネルギーは甚大である。そして、熱間で鍛
造し、室温で機械加工することになるが、熱間温度と室
温（約２５℃）とでは極端に温度が異なるため、熱膨張
を見込んで鍛造を実施しても得られた鍛造品の寸法精度
は良くない。そのために機械加工が必須となる。With hot forging, plastic working is easy. However, in hot forging, for example, 10
Since the work must be heated at a high temperature of 00 ° C. or more, its thermal energy is enormous. Then, forging is performed hot and machining is performed at room temperature. However, the temperature is extremely different between the hot temperature and room temperature (about 25 ° C.). The dimensional accuracy of the forged product is not good. Therefore, machining is essential.
【０００４】そこで、本発明者らは、エンジン用吸気弁
を冷間鍛造法で製造する研究を鋭意進めた。しかし、マ
ルテンサイト系耐熱鋼は難加工材であり、延性に乏しい
ことから、冷間鍛造が難かしいことは周知のことであ
る。図９（ａ），（ｂ）は据込み鍛造の原理図である。
（ａ）は比較的大径のビレット１０１を金型１０２にセ
ットし、パンチ１０３で押圧するものであり、ビレット
１０１の径をｄ０、断面積をＡ０、長さをＬ０とし、金
型１０２の絞り穴の径をｄ１、断面積をＡ１とし、ビレ
ット１０１と金型１０２壁面との摩擦係数μとすると、
次の関係が成立する。絞り荷重は、断面減少率に比例す
る。 ここで、断面減少率＝（Ａ０−Ａ１）／Ａ０＝１−（ｄ
１／ｄ０）2 また、ビレットと金型との間に接触抵抗が発生し、この
接触抵抗は、μ×接触面積に比例する。 ここで、接触面積＝（π・ｄ０・Ｌ０）[0004] Therefore, the present inventors have intensively studied to manufacture an intake valve for an engine by a cold forging method. However, it is well known that cold forging is difficult because martensitic heat-resistant steel is a difficult-to-work material and has poor ductility. FIGS. 9A and 9B are diagrams showing the principle of upsetting forging.
(A) is a method in which a billet 101 having a relatively large diameter is set in a mold 102 and pressed by a punch 103. The diameter of the billet 101 is d0, the sectional area is A0, the length is L0, and the billet 101 is When the diameter of the drawing hole is d1, the sectional area is A1, and the friction coefficient μ between the billet 101 and the wall surface of the mold 102 is:
The following relationship holds: The drawing load is proportional to the area reduction rate. Here, the area reduction rate = (A0−A1) / A0 = 1− (d
1 / d0) 2 Also, contact resistance occurs between the billet and the mold, and this contact resistance is proportional to μ × contact area. Here, contact area = (π · d0 · L0)
【０００５】ビレット１０１が大径であれば、その長さ
Ｌ０は十分に小さいので、前記摩擦抵抗は小さくなり、
パンチ力Ｐ０は小さくなる。パンチ力Ｐ０が小さけれ
ば、金型１０２に発生する金型面圧は比例的に小さくな
り、金型破壊の心配はない。しかし、断面減少率は大き
いので、絞り荷重は大きくなる。従って、断面減少率は
上限がある。If the billet 101 has a large diameter, its length L0 is sufficiently small, so that the frictional resistance becomes small.
The punch force P0 decreases. If the punch force P0 is small, the mold surface pressure generated in the mold 102 is proportionally reduced, and there is no fear of mold breakage. However, since the area reduction rate is large, the drawing load becomes large. Therefore, there is an upper limit for the cross-sectional reduction rate.
【０００６】（ｂ）は比較的小径のビレット１０５を金
型１０６にセットし、パンチ１０７で押圧するものであ
り、ビレット１０５の径をｄ３、断面積をＡ３、長さを
Ｌ３とし、金型１０６の絞り穴の径をｄ１、断面積をＡ
１とし、ビレット１０５と金型１０６壁面との摩擦係数
μとすると、次の関係が成立する。絞り荷重は、断面減
少率に比例する。 ここで、断面減少率＝（Ａ３−Ａ１）／Ａ３＝１−（ｄ
１／ｄ３）2 また、ビレットと金型との間に接触抵抗が発生し、この
接触抵抗は、μ×接触面積に比例する。 ここで、接触面積＝（π・ｄ３・Ｌ３）FIG. 1B shows a comparative example in which a billet 105 having a relatively small diameter is set in a mold 106 and pressed by a punch 107. The billet 105 has a diameter d3, a sectional area A3 and a length L3. The diameter of the throttle hole of 106 is d1, and the cross-sectional area is A
If the friction coefficient μ between the billet 105 and the wall surface of the mold 106 is set to 1, the following relationship is established. The drawing load is proportional to the area reduction rate. Here, the area reduction rate = (A3-A1) / A3 = 1- (d
1 / d3) 2 Also, contact resistance occurs between the billet and the mold, and this contact resistance is proportional to μ × contact area. Here, contact area = (π · d3 · L3)
【０００７】ビレット１０５が小径であるから、断面減
少率は小さい。ビレット１０５の径ｄ３が、大径のビレ
ット１０１の径ｄ１の１／２であれば、（π／４）・
（ｄ０）2・Ｌ０＝（π／４）・（ｄ３）2・Ｌ３＝（π
／４）・（ｄ１／２）2・Ｌ３から、Ｌ３＝４・Ｌ０と
なる。このように、ビレット１０５が小径であれば、そ
の長さＬ３は径の比の２乗に逆比例して大きくなる。上
の例では４倍になり接触抵抗も４倍となる。接触抵抗は
金型を押し広げる力、即ち金型を破壊する力となるか
ら、小径のビレットほど金型面圧は大きくなる。従っ
て、小径のビレットでは金型面圧の点から断面減少率に
下限がある。Since the billet 105 has a small diameter, the cross-sectional reduction rate is small. If the diameter d3 of the billet 105 is １ ／ of the diameter d1 of the large billet 101, (π / 4) ·
(D0) 2 · L0 = (π / 4) · (d3) 2 · L3 = (π
From (/ 4) · (d1 / 2) 2 · L3, L3 = 4 · L0. Thus, if the billet 105 has a small diameter, its length L3 increases in inverse proportion to the square of the diameter ratio. In the above example, the contact resistance is quadrupled and the contact resistance is also quadrupled. Since the contact resistance is a force for expanding the mold, that is, a force for breaking the mold, the smaller the billet, the larger the mold surface pressure. Therefore, there is a lower limit to the cross-sectional reduction rate in the case of a small-diameter billet in terms of mold surface pressure.
【０００８】そこで、本発明者らは軸部の冷間鍛造を詳
細に研究し、好適な断面減少率の範囲を確立することに
成功した。Accordingly, the present inventors have studied in detail the cold forging of the shaft portion and have succeeded in establishing a suitable range of the area reduction rate.
【０００９】[0009]
【課題を解決するための手段】具体的には、請求項１は
Ｃが０．３５％〜０．５５％、Ｃｒが５％〜１２％の範
囲にあるマルテンサイト系耐熱鋼のビレットを準備し、
このビレットを冷間鍛造法にて軸部及び傘部からなる吸
気弁を成形する方法であって、軸部の第１段成形は、断
面減少率７０％〜８０％の範囲で実施することを特徴と
したエンジン用吸気弁の成形方法である。Specifically, claim 1 provides a billet of a martensitic heat-resistant steel having a C content of 0.35% to 0.55% and a Cr content of 5% to 12%. And
This billet is a method of forming an intake valve comprising a shaft portion and an umbrella portion by a cold forging method, and the first-stage forming of the shaft portion is performed at a cross-sectional reduction rate of 70% to 80%. This is a method for molding an intake valve for an engine.
【００１０】Ｃが０．３５％未満であると十分な焼入れ
硬さが得られず、また０．５５％を超えると焼入れ硬さ
は十分得られるが有効Ｃｒの欠乏が生じ耐食性が低下す
る。従って、Ｃは０．３５％〜０．５５％の範囲とす
る。Ｃｒが５％未満であると十分な耐熱性、耐酸化性及
び耐食性が得られず、また１２％を超えるとフェライト
相が現れ、焼入れ硬化性が低下する。従って、Ｃｒは５
％〜１２％の範囲とする。If C is less than 0.35%, sufficient quenching hardness cannot be obtained, and if C exceeds 0.55%, sufficient quenching hardness can be obtained, but effective Cr is deficient and corrosion resistance is reduced. Therefore, C is set in the range of 0.35% to 0.55%. If the Cr content is less than 5%, sufficient heat resistance, oxidation resistance and corrosion resistance cannot be obtained, and if it exceeds 12%, a ferrite phase appears and the quench hardenability decreases. Therefore, Cr is 5
% To 12%.
【００１１】また、断面減少率が８０％を超えると絞り
荷重が過大になり、また、断面減少率が７０％を下回る
と接触抵抗が過大となり、金型破壊に繋がる。従って、
断面減少率は７０％〜８０％の範囲にする。残りの断面
減少は第２段以降の工程で実施する。第２段工程以降で
は、吸気弁の製造上、金型とビレットの接触は軽微とな
り、実質的に接触抵抗を考えなくとも良いので、断面減
少率３０％未満の冷間鍛造が可能である。On the other hand, if the cross-section reduction rate exceeds 80%, the drawing load becomes excessively large, and if the cross-section reduction rate is less than 70%, the contact resistance becomes excessively large, which leads to mold breakage. Therefore,
The area reduction rate is in the range of 70% to 80%. The remaining reduction in cross section is performed in the second and subsequent steps. In the second and subsequent steps, the contact between the mold and the billet becomes small in the manufacture of the intake valve, and it is not necessary to consider contact resistance substantially. Therefore, cold forging with a reduction in area of less than 30% is possible.
【００１２】マルテンサイト系耐熱鋼の成分を限定し、
第１段の断面減少率を適正範囲に留めることで吸気弁の
軸部の冷間鍛造が可能となった。[0012] The components of the martensitic heat-resistant steel are limited,
By keeping the cross-sectional reduction rate of the first stage within an appropriate range, cold forging of the shaft portion of the intake valve became possible.
【００１３】請求項２は、Ｃが０．３５％〜０．５５
％、Ｃｒが５％〜１２％の範囲にあるマルテンサイト系
耐熱鋼のビレットを準備し、このビレットを断面減少率
７０％〜８０％の範囲で冷間鍛造することで軸部の第１
段成形を実施し、この軸部の残りの絞り加工を第２段以
降の冷間鍛造で実施し、少なくとも据込み率７０％で且
つワークが２００℃を超えないように温度制御しつつ傘
部を冷間鍛造することを特徴としたエンジン用吸気弁の
成形方法である。According to a second aspect of the present invention, C is 0.35% to 0.55%.
% And Cr in the range of 5% to 12% are prepared in a martensitic heat-resistant steel, and the billet is cold-forged in a range of 70% to 80% in cross-sectional reduction, thereby forming the first shaft portion.
Step forming is performed, and the remaining drawing of the shaft is performed by cold forging in the second and subsequent steps, and the umbrella section is controlled while maintaining the work up to at least 70% and at a temperature not exceeding 200 ° C. And a cold forging method for forming an intake valve for an engine.
【００１４】マルテンサイト系耐熱鋼の成分を限定し、
第１段の断面減少率を適正範囲に留め、且つ２００℃以
下で傘部を成形することにより、エンジン用吸気弁の完
全冷間鍛造化を実現することができた。[0014] The composition of the martensitic heat-resistant steel is limited,
By keeping the cross-sectional reduction rate of the first stage within an appropriate range and forming the umbrella portion at 200 ° C. or lower, complete cold forging of the intake valve for the engine could be realized.
【００１５】請求項３は、ビレットを鍛造前に、８５０
℃〜９５０℃で焼鈍処理を施すことを特徴とする。予め
焼鈍したことにより、次の冷間鍛造が円滑に実施でき
る。[0015] The third aspect is that the billet is 850 before forging.
It is characterized in that an annealing treatment is performed at a temperature of 950C to 950C. By performing the annealing in advance, the next cold forging can be smoothly performed.
【００１６】[0016]
【発明の実施の形態】本発明の実施の形態を添付図に基
づいて以下に説明する。なお、本発明で対象とした実施
例１，２の成分組成は次の表１に示す。Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the component compositions of Examples 1 and 2 targeted in the present invention are shown in Table 1 below.
【００１７】[0017]
【表１】 [Table 1]
【００１８】図１（ａ）〜（ｄ）は本発明に係る冷間鍛
造の工程図（前半、軸部形成）である。 （ａ）：直径Ｄ、長さＬのビレット１を第１金型２（先
端に円錐面を形成する）にセットし第１パンチ３で据え
込む。この工程は省略可能なものであるから、成形段数
にはカウントしない。 （ｂ）：先端が円錐になった中間品４（中間加工品を
「中間品」と呼ぶことにする。以下同じ。）を第２金型
５（径ｄ２の軸部を形成する）にセットし第２パンチ６
で据え込む。この間に、中間品４は第２金型５壁面と全
面的に接触して大きな「接触抵抗」が発生する。すなわ
ち、「軸部の第１段成形」は第２金型５で、径Ｄを径ｄ
２に絞ったこという。1 (a) to 1 (d) are process drawings (first half, formation of a shaft portion) of the cold forging according to the present invention. (A): A billet 1 having a diameter D and a length L is set in a first mold 2 (having a conical surface at the tip) and set up with a first punch 3. Since this step can be omitted, it is not counted in the number of molding steps. (B): An intermediate product 4 having a conical tip (an intermediate processed product is referred to as an “intermediate product”; the same applies hereinafter) is set in a second mold 5 (forming a shaft portion having a diameter d2). Second punch 6
Upset. During this time, the intermediate product 4 comes into full contact with the wall surface of the second mold 5 to generate a large “contact resistance”. That is, the “first-stage molding of the shaft portion” is performed by the second mold 5 and the diameter D is changed to the diameter d.
It is said that we narrowed down to 2.
【００１９】図２は断面減少率と絞り荷重との関係を調
べたグラフであり、横軸は断面減少率、縦軸は絞り荷重
である。ビレットは表１に示すマルテンサイト系耐熱鋼
（実施例１，２）、鍛造前の径Ｄは１４〜１８ｍｍ、第
１段成形後の軸部の径ｄ２は７．５ｍｍとした。断面減
少率に比例して絞り荷重が増加する。絞り荷重が過大と
なるとパンチや金型を痛めることになるので、４７５Ｎ
を上限とし、断面減少率を８０％に留めることにした。FIG. 2 is a graph showing the relationship between the area reduction rate and the drawing load. The horizontal axis represents the area reduction rate and the vertical axis represents the drawing load. The billet was a martensitic heat-resistant steel shown in Table 1 (Examples 1 and 2), the diameter D before forging was 14 to 18 mm, and the diameter d2 of the shaft after the first-stage molding was 7.5 mm. The drawing load increases in proportion to the area reduction rate. If the drawing load is too large, it will damage the punch and the mold.
, And the cross-section reduction rate is kept at 80%.
【００２０】図３は断面減少率と金型面圧との関係を調
べたグラフであり、断面減少率が小さくなるほどにビレ
ットと金型の接触面積が増加し、接触抵抗が増加するこ
とから金型面圧は増加する。金型面圧の許容値を２２０
ｋｇ／ｍｍ2とし、断面減少率の下限値を７０％にする
ことにした。FIG. 3 is a graph showing the relationship between the area reduction rate and the mold surface pressure. The smaller the area reduction rate, the larger the contact area between the billet and the mold and the higher the contact resistance. The mold surface pressure increases. The allowable value of mold surface pressure is 220
kg / mm 2, and the lower limit of the area reduction rate is set to 70%.
【００２１】図１に戻って、第１段成形後の軸部の加工
及び傘部の加工を引き続き説明する。 （ｃ）：径ｄ２の軸部を有する中間品７を第３金型８
（径ｄ３の軸部を形成する）にセットし第３パンチ９で
据え込む。中間品７の軸部（径ｄ２の部分）は、第３金
型８に接触していない。従って、接触抵抗は考えなくて
もよい。従って、ここで実施する軸部の第２段成形の断
面減少率は３０％以下の例えば１０％とする。 （ｄ）：径ｄ３の軸部を有する中間品１１を第４金型１
２（径ｄ４の軸部を形成する）にセットし第４パンチ１
３で据え込む。ここで実施する軸部の第３段成形の断面
減少率は残り断面減少率（例えば１０％）とする。すな
わち、（ｂ）の第１段成形では断面減少率７０〜８０％
とし、（ｃ），（ｄ）の第２段・第３段成形で残りの断
面減少率を適当に配分して実施すればよい。Returning to FIG. 1, the processing of the shaft portion and the processing of the umbrella portion after the first-stage molding will be described continuously. (C): An intermediate product 7 having a shaft portion with a diameter d2 is placed in a third mold 8
(Forming a shaft portion with a diameter d3) and upsetting with the third punch 9. The shaft portion (the portion of the diameter d2) of the intermediate product 7 is not in contact with the third mold 8. Therefore, it is not necessary to consider the contact resistance. Therefore, the cross-sectional reduction rate of the second-stage molding of the shaft portion performed here is 30% or less, for example, 10%. (D): An intermediate product 11 having a shaft portion having a diameter d3 is placed in a fourth mold 1
2 (forming a shaft portion of diameter d4) and the fourth punch 1
Upset at 3. The sectional reduction rate of the third-stage molding of the shaft portion performed here is the remaining sectional reduction rate (for example, 10%). That is, in the first-stage molding of (b), the cross-sectional reduction rate is 70 to 80%.
In the second and third molding steps (c) and (d), the remaining cross-sectional reduction rate may be appropriately distributed.
【００２２】図４（ａ）〜（ｃ）は本発明に係る冷間鍛
造の工程図（後半、傘部形成）である。 （ａ）：径ｄ４の軸部を有し、且つ径Ｄ１の傘部を有す
る中間品１４を第５金型１５（径Ｄ２の傘部を形成す
る）にセットし第５パンチ１６で据え込む。 （ｂ）：径Ｄ２の傘部を有する中間品１７を第６金型１
８（径Ｄ３の傘部を形成する）にセットし第６パンチ１
９で据え込む。 （ｃ）：以上の６工程を経て完成した吸気弁２０を示
す。FIGS. 4 (a) to 4 (c) are process drawings of cold forging according to the present invention (second half, umbrella formation). (A): An intermediate product 14 having a shaft portion with a diameter d4 and having an umbrella portion with a diameter D1 is set in a fifth mold 15 (forming an umbrella portion with a diameter D2) and upset with a fifth punch 16. . (B): An intermediate product 17 having an umbrella portion having a diameter D2 is formed by using a sixth mold 1
8 (forming an umbrella portion of diameter D3) and setting the sixth punch 1
Upset at 9. (C): shows the intake valve 20 completed through the above six steps.
【００２３】なお、今まで説明しなかったが、傘部を７
０％以上の据込み率で冷間鍛造すると割れることがあ
る。そこで、その要因及び対策を以下に説明する。図５
（ａ），（ｂ）は吸気弁における据込み率の説明図であ
る。（ｂ）の吸気弁２０は軸部２１と傘部２２とからな
り、軸部２１は径ｄ６、長さｌ６のストレート部分とす
る。傘部２２の長さ（高さ）はＬ６とする。軸部２１の
体積ｖ６は（π／４）×（ｄ６）2×ｌ６で求まる。
（ａ）において、ビレット１を軸部分１ａと傘部分１ｂ
に仮想的に区分けする。具体的には軸部分１ａを前記ｖ
６相当高さ｛ｖ６÷（π／４）×Ｄ2｝とし、残りを傘
部分１ｂの高さＬ０とすればよい。据込み率は据込み長
さを据込み前の長さで除した値であるから、本発明にお
いては、据込み率は｛（Ｌ０−Ｌ６）／Ｌ０｝×１００
（％）と定義する。Although not described so far, the umbrella section is 7
When cold forging is performed at an upsetting rate of 0% or more, cracking may occur. Therefore, the factors and countermeasures will be described below. FIG.
(A), (b) is explanatory drawing of the upsetting rate in an intake valve. The intake valve 20 of (b) comprises a shaft portion 21 and an umbrella portion 22, and the shaft portion 21 is a straight portion having a diameter d6 and a length 16. The length (height) of the umbrella portion 22 is L6. The volume v6 of the shaft portion 21 is determined by (π / 4) × (d6) 2 × 16.
In (a), the billet 1 is divided into a shaft portion 1a and an umbrella portion 1b.
Is virtually divided into Specifically, the shaft portion 1a is
6, the height may be {v6} (π / 4) × D 2 }, and the rest may be the height L0 of the umbrella portion 1b. Since the upsetting ratio is a value obtained by dividing the upsetting length by the length before the upsetting, in the present invention, the upsetting ratio is {(L0−L6) / L0} × 100.
(%).
【００２４】ところで、上記の冷間鍛造工程でワーク
（中間品、完成品）が熱くなることが分かった。そこ
で、温度を計測した。図６は吸気弁を冷間鍛造したとき
の据込み率と表面温度の関係を示すグラフであり、横軸
は据込み率、縦軸は表面温度である。冷間鍛造では変形
しにくい素材を無理に塑性変形するために、据込み率に
比例して表面温度が上り、据込み率７０％では約２５０
度、据込み率８０％では約３００度に達した。By the way, it was found that the work (intermediate product, finished product) becomes hot in the cold forging process. Then, the temperature was measured. FIG. 6 is a graph showing the relationship between the upsetting ratio and the surface temperature when the intake valve is cold forged. The horizontal axis represents the upsetting ratio, and the vertical axis represents the surface temperature. In order to forcibly plastically deform a material that is difficult to deform by cold forging, the surface temperature increases in proportion to the upsetting rate, and about 250% at an upsetting rate of 70%.
The degree reached about 300 degrees when the upsetting ratio was 80%.
【００２５】そこで本発明者らは温度と耐熱鋼の割れの
関係を調べた。図７はマルテンサイト系耐熱鋼の温度と
据込み限界との関係を示すグラフであり、横軸は試験温
度、縦軸は割れが発生したときの据込み率を示す。試験
はワークが加工熱で温度上昇するときであっても、冷却
するなどして試験温度に強制的に保って実施した。実施
例１，２の合金成分は先に示した通りである。Therefore, the present inventors examined the relationship between temperature and cracks in heat-resistant steel. FIG. 7 is a graph showing the relationship between the temperature of the martensitic heat-resistant steel and the upsetting limit. The horizontal axis shows the test temperature, and the vertical axis shows the upsetting ratio when a crack occurs. The test was carried out by forcibly maintaining the test temperature, such as by cooling, even when the temperature of the workpiece was increased by the processing heat. The alloy components of Examples 1 and 2 are as described above.
【００２６】図７において実施例１，２共に、−５０℃
〜６００℃の領域では３００℃付近を極小値とした下に
凸の曲線となることが分かった。細かくは、実施例１
（１２％Ｃｒ）では２００℃で据込み限界が７０％を切
り、約３５０℃で７０％を回復する。実施例５（８％Ｃ
ｒ）では２００℃で据込み限界が７２％であるから、実
施例１よりは有利である。このことから、マルテンサイ
ト系耐熱鋼のビレットを７０％の据込み率で且つ冷間鍛
造法で吸気弁にするには、ビレットや中間品の温度を２
００℃以下にすれば、割れは防止できることが分かる。In FIG. 7, both of Examples 1 and 2 are -50.degree.
It was found that in the region from to 600 ° C., a downward convex curve having a minimum value near 300 ° C. was obtained. Detailed description is given in Example 1.
With (12% Cr), the upsetting limit falls below 70% at 200 ° C, and recovers 70% at about 350 ° C. Example 5 (8% C
In the case of r), the upsetting limit is 72% at 200 ° C., which is more advantageous than that of the first embodiment. Therefore, in order to make the billet of the martensitic heat-resistant steel into an intake valve by the cold forging method at an upsetting rate of 70%, the temperature of the billet and the intermediate product must be 2%.
It can be seen that cracking can be prevented by setting the temperature to 00 ° C. or lower.
【００２７】ビレットや中間品の温度を２００℃以下に
保つには、金型を冷却水等で強制冷却する、ワークの傘
部を空気等で直接冷却する、の双方若しくは一方を実施
すればよい。In order to keep the temperature of the billet or the intermediate product at 200 ° C. or lower, it is only necessary to carry out forced cooling of the mold with cooling water or the like and / or cooling of the work head directly with air or the like. .
【００２８】以上をまとめるとエンジン用吸気弁は、次
の工程で製造することができる。図８は本発明に係るエ
ンジン用吸気弁の製造工程図であり、ＳＴ××はステッ
プ番号を示し、図１及び図４を参照しつつ説明する。 ＳＴ０１：実施例１，２で指定した成分のマルテンサイ
ト系耐熱鋼のビレットを準備する。例えばビレットの径
は１６ｍｍである。 ＳＴ０２：８５０℃〜９５０℃で焼鈍処理をする。 ＳＴ０３：スケールを除去する。 ＳＴ０４：潤滑処理をする。In summary, the intake valve for an engine can be manufactured in the following steps. FIG. 8 is a manufacturing process diagram of the engine intake valve according to the present invention, where STxx indicates step numbers, which will be described with reference to FIGS. ST01: A billet of a martensitic heat-resistant steel having the components specified in Examples 1 and 2 is prepared. For example, the billet diameter is 16 mm. ST02: Anneal at 850 ° C to 950 ° C. ST03: The scale is removed. ST04: Perform lubrication processing.
【００２９】ＳＴ０５：（参照図１（ａ），（ｂ））、
断面減少率７０％〜８０％で軸部の第１段成形を実施す
る。例えば、７．５ｍｍまで第１段成形する。１６ｍｍ
→７．５ｍｍは、断面減少率７８％となる。 ＳＴ０６：（参照図１（ｃ），（ｄ））、軸部を例えば
８７％まで断面減少させるとして、差引き９％を第２段
以降で成形する。 ＳＴ０７：（参照図２（ａ），（ｂ））、据込み率７０
％以上の傘打ちを行うが、このときにワークを２００℃
以下に保つ。据込み率を例えば７２％にすることで、図
４（ｃ）の吸気弁２０を製造することができる。ST05: (see FIGS. 1 (a) and 1 (b))
The first-stage molding of the shaft portion is performed at a cross-sectional reduction rate of 70% to 80%. For example, the first stage molding is performed to 7.5 mm. 16mm
→ 7.5 mm results in a cross-sectional reduction rate of 78%. ST06: (See FIGS. 1 (c) and 1 (d)) Assuming that the shaft portion is reduced in cross section to, for example, 87%, the difference 9% is formed in the second and subsequent steps. ST07: (see FIGS. 2A and 2B), upsetting rate 70
% Umbrella, but at this time the work is 200 ° C
Keep below. By setting the upsetting ratio to, for example, 72%, the intake valve 20 of FIG. 4C can be manufactured.
【００３０】なお、傘部に対する据込み率は、７０％未
満では一定の径の傘部を得るのに、太いビレットを準備
しなければならず、ビレットが太くなると軸部の成形が
難しくなる。しかし、据込み率が７０％を大きく上回る
と、本発明によれば冷却をより強化しなければならない
ので、据込み率は７０％〜７５％範囲とすることが好ま
しい。When the upsetting ratio of the head portion is less than 70%, a thick billet must be prepared to obtain a head portion having a constant diameter. When the billet becomes thick, the shaping of the shaft becomes difficult. However, if the upsetting ratio is significantly higher than 70%, the cooling must be further strengthened according to the present invention, so that the upsetting ratio is preferably in the range of 70% to 75%.
【００３１】また、本実施例では軸部を４工程（実質３
工程）で成形したが、この工程数の増減は任意である。
傘部の成形も同様である。Further, in this embodiment, the shaft portion is processed in four steps (substantially 3 steps).
Although the molding was performed in step (3), the increase or decrease in the number of steps is optional.
The same applies to the formation of the umbrella.
【００３２】[0032]
【発明の効果】本発明は上記構成により次の効果を発揮
する。請求項１は、マルテンサイト系耐熱鋼の成分を限
定し、第１段の断面減少率を適正範囲に留めることで吸
気弁の軸部の冷間鍛造が可能となり、冷間鍛造であるか
ら、熱エネルギーの大幅な節約が可能となり、スケール
が発生しないことから歩留りが良く、熱膨張がないので
仕上り寸法精度が極めてよくて機械加工を省くことがで
き、エンジン用吸気弁を効率よく製造することができ
る。According to the present invention, the following effects are exhibited by the above configuration. Claim 1 restricts the components of the martensitic heat-resistant steel, and enables cold forging of the shaft portion of the intake valve by keeping the cross-sectional reduction rate of the first stage in an appropriate range. Great savings in heat energy, no scale, good yield, no thermal expansion, excellent finish dimensional accuracy, no machining required, and efficient production of engine intake valves Can be.
【００３３】請求項２は、マルテンサイト系耐熱鋼の成
分を限定し、第１段の断面減少率を適正範囲に留め、且
つ２００℃以下で傘部を成形することにより、エンジン
用吸気弁の完全冷間鍛造化を実現することができた。冷
間鍛造であるから、熱エネルギーの大幅な節約が可能と
なり、スケールが発生しないことから歩留りが良く、熱
膨張がないので仕上り寸法精度が極めてよくて機械加工
を省くことができ、エンジン用吸気弁を効率よく製造す
ることができる。[0033] The second aspect of the present invention is to limit the composition of the martensitic heat-resistant steel, to keep the first-stage cross-sectional reduction rate within an appropriate range, and to form the umbrella portion at 200 ° C or less, thereby obtaining an engine intake valve. Complete cold forging was realized. Cold forging allows for significant savings in thermal energy, yields are good because no scale is generated, and there is no thermal expansion, so the finished dimensional accuracy is extremely good, so machining can be omitted, and engine intake The valve can be manufactured efficiently.
【００３４】請求項３は、ビレットを鍛造前に、８５０
℃〜９５０℃で焼鈍処理を施すことを特徴とする。予め
焼鈍したことにより、次の冷間鍛造が円滑に実施でき
る。The third aspect is that the billet is 850 before forging.
It is characterized in that an annealing treatment is performed at a temperature of 950C to 950C. By performing the annealing in advance, the next cold forging can be smoothly performed.
【図１】本発明に係る冷間鍛造の工程図（前半、軸部形
成）FIG. 1 is a process diagram of a cold forging according to the present invention (first half, shaft portion formation).
【図２】断面減少率と絞り荷重との関係を調べたグラフFIG. 2 is a graph showing a relationship between a cross-sectional reduction rate and a drawing load.
【図３】断面減少率と金型面圧との関係を調べたグラフFIG. 3 is a graph showing the relationship between the cross-sectional reduction rate and the mold surface pressure.
【図４】本発明に係る冷間鍛造の工程図（後半、傘部形
成）FIG. 4 is a process diagram of cold forging according to the present invention (second half, umbrella formation)
【図５】吸気弁における据込み率の説明図FIG. 5 is an explanatory diagram of an upsetting ratio in an intake valve.
【図６】吸気弁を冷間鍛造したときの据込み率と表面温
度の関係を示すグラフFIG. 6 is a graph showing the relationship between the upsetting ratio and the surface temperature when the intake valve is cold forged.
【図７】マルテンサイト系耐熱鋼の温度と据込み限界と
の関係を示すグラフFIG. 7 is a graph showing the relationship between the temperature of martensitic heat-resistant steel and the upsetting limit.
【図８】本発明に係るエンジン用吸気弁の製造工程図FIG. 8 is a manufacturing process diagram of an intake valve for an engine according to the present invention.
【図９】据込み鍛造の原理図FIG. 9 is a principle diagram of upsetting forging.
１…ビレット、２０…エンジン用吸気弁、２１…軸部、
２２…傘部。DESCRIPTION OF SYMBOLS 1 ... Billet, 20 ... Engine intake valve, 21 ... Shaft part,
22 ... Umbrella part.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｃ２２Ｃ 38/18 Ｃ２２Ｃ 38/18 ──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification code FI C22C 38/18 C22C 38/18
Claims (3)
％〜１２％の範囲にあるマルテンサイト系耐熱鋼のビレ
ットを準備し、このビレットを冷間鍛造法にて軸部及び
傘部からなる吸気弁を成形する方法であって、前記軸部
の第１段成形は、断面減少率７０％〜８０％の範囲で実
施することを特徴としたエンジン用吸気弁の成形方法。C. 0.35% to 0.55% of C and 5% of Cr
% Of a martensitic heat-resistant steel in the range of 12% to 12%, and forming an intake valve comprising a shaft portion and an umbrella portion by cold forging. The method of forming an intake valve for an engine, wherein the one-step molding is performed at a cross-sectional reduction rate of 70% to 80%.
％〜１２％の範囲にあるマルテンサイト系耐熱鋼のビレ
ットを準備し、このビレットを断面減少率７０％〜８０
％の範囲で冷間鍛造することで軸部の第１段成形を実施
し、この軸部の残りの絞り加工を第２段以降の冷間鍛造
で実施し、少なくとも据込み率７０％で且つワークが２
００℃を超えないように温度制御しつつ傘部を冷間鍛造
することを特徴としたエンジン用吸気弁の成形方法。2. C is 0.35% to 0.55% and Cr is 5%.
% Of a martensitic heat-resisting steel in the range of 12% to 12%, and reducing the billet to a cross-sectional reduction rate of 70% to 80%.
% Of the shaft portion by cold forging in the range of%, and the remaining drawing of this shaft portion is performed by the second and subsequent stages of cold forging. Work 2
A method for forming an intake valve for an engine, comprising cold forging an umbrella portion while controlling the temperature so as not to exceed 00 ° C.
５０℃で焼鈍処理を施すことを特徴とした請求項１又は
請求項２記載のエンジン用吸気弁の成形方法。3. Prior to forging the billet, the billet is heated to 850 ° C. to 9 ° C.
The method for forming an intake valve for an engine according to claim 1 or 2, wherein the annealing treatment is performed at 50 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23873297A JPH1181932A (en) | 1997-09-03 | 1997-09-03 | Method of forming intake valve for engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23873297A JPH1181932A (en) | 1997-09-03 | 1997-09-03 | Method of forming intake valve for engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH1181932A true JPH1181932A (en) | 1999-03-26 |
Family
ID=17034444
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23873297A Pending JPH1181932A (en) | 1997-09-03 | 1997-09-03 | Method of forming intake valve for engine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH1181932A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005152950A (en) * | 2003-11-26 | 2005-06-16 | Honda Motor Co Ltd | Forging method |
| JP2008215157A (en) * | 2007-03-02 | 2008-09-18 | Aisan Ind Co Ltd | Engine valve |
| CN102990288A (en) * | 2012-08-17 | 2013-03-27 | 大连大高阀门股份有限公司 | Nuclear secondary stainless steel valve body forging process |
-
1997
- 1997-09-03 JP JP23873297A patent/JPH1181932A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005152950A (en) * | 2003-11-26 | 2005-06-16 | Honda Motor Co Ltd | Forging method |
| JP2008215157A (en) * | 2007-03-02 | 2008-09-18 | Aisan Ind Co Ltd | Engine valve |
| CN102990288A (en) * | 2012-08-17 | 2013-03-27 | 大连大高阀门股份有限公司 | Nuclear secondary stainless steel valve body forging process |
| CN102990288B (en) * | 2012-08-17 | 2015-08-19 | 大连大高阀门股份有限公司 | Core secondary stainless steel body Forging Technology |
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