JPH0748659A - Production of titanium alloy bar suitable for production of engine valve - Google Patents
Production of titanium alloy bar suitable for production of engine valveInfo
- Publication number
- JPH0748659A JPH0748659A JP19492293A JP19492293A JPH0748659A JP H0748659 A JPH0748659 A JP H0748659A JP 19492293 A JP19492293 A JP 19492293A JP 19492293 A JP19492293 A JP 19492293A JP H0748659 A JPH0748659 A JP H0748659A
- Authority
- JP
- Japan
- Prior art keywords
- titanium alloy
- valve
- production
- rod
- straightening
- 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.)
- Withdrawn
Links
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- Forging (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は自動車、二輪車等のエン
ジンに使用される大量生産を可能としたエンジンバルブ
用のチタン合金棒に関する。詳しくは、エンジンバルブ
を製造する際に、傘部鍛造後の焼鈍において、バルブ粗
形材の軸部の曲りを起こさないチタン合金棒の製造方法
に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium alloy rod for an engine valve, which can be mass-produced for use in engines of automobiles and motorcycles. More specifically, the present invention relates to a method for manufacturing a titanium alloy rod that does not cause bending of the shaft portion of a rough valve material during annealing after forging an umbrella portion when manufacturing an engine valve.
【0002】[0002]
【従来の技術】自動車等のエンジン燃焼室の吸、排気孔
に設けられるバルブは、傘部と、これに連続する軸部お
よび軸端部で構成される。例えば直径7mmの鋼製棒材を
250mm長さに切断し、その一端部を通電加熱しつつ熱
間にてアップセット鍛造(電気鍛縮法)し、つづいて傘
部を熱間にて型鍛造してきのこ状の粗形材とし、歪取り
焼鈍を行い、次いで切削、研削加工により最終形状に仕
上げた後、耐磨耗性を付与するために軟窒化処理等の表
面処理を行っているのが通例である。エンジンバルブに
おける傘部のフェース部、軸部、および軸端部のいずれ
も耐磨耗性が要求される。また、バルブの使用環境から
バルブには高温強度、耐蝕性、耐酸化性を具えていなけ
ればならず、従来のバルブは耐熱鋼で製作されるのが一
般的であった。2. Description of the Related Art A valve provided in an intake / exhaust hole of an engine combustion chamber of an automobile or the like comprises an umbrella portion, a shaft portion and a shaft end portion continuous with the umbrella portion. For example, a steel rod with a diameter of 7 mm is cut into a length of 250 mm, one end of which is upset forged (electrical contraction method) in a hot state while being energized and heated, and subsequently a die is forged in a hot state of the umbrella part. As a mushroom-shaped rough material, strain relief annealing is performed, then after finishing to the final shape by cutting and grinding, surface treatment such as soft nitriding treatment is given to impart abrasion resistance. Is customary. Abrasion resistance is required for the face portion, the shaft portion, and the shaft end portion of the umbrella portion of the engine valve. In addition, the valve must have high-temperature strength, corrosion resistance, and oxidation resistance because of the environment in which the valve is used, and conventional valves are generally made of heat-resistant steel.
【0003】ところで、近年自動車等のエンジンは、馬
力を低下させることなく、燃費を改善するために軽量化
が求められている。上下運動を高速でくりかえすエンジ
ンバルブについては、軽量化による燃費改善の波及効果
が極めて大きく、そのため比強度の高いチタン合金材の
採用が試みられている。例えば競争用自動車の吸気バル
ブには、α+βチタン合金の代表例であるTi−6Al
−4Vが多く用いられてきた。しかし、エンジンバルブ
にチタン合金をそのまま使用した場合は、バルブシー
ト、バルブガイド等の相手材とバルブの各部との摺動に
よる磨耗が生じ、耐久性に乏しいという問題がある。こ
のためチタン合金製バルブは、耐熱鋼製バルブとほぼ同
様の方法で仕上げ加工まで行い、軸部に耐磨耗性を付与
するため、Mo溶射を施している。従って、製造コスト
が高くなり、経済性を無視した製品となっている。By the way, in recent years, engines of automobiles and the like are required to be light in weight in order to improve fuel efficiency without lowering horsepower. For engine valves that repeat vertical movements at high speed, the ripple effect of fuel efficiency improvement due to weight reduction is extremely large, and therefore, the use of titanium alloy materials with high specific strength has been attempted. For example, for an intake valve of a competition vehicle, Ti-6Al, which is a typical example of α + β titanium alloy, is used.
-4V has been used frequently. However, when a titanium alloy is used as it is for an engine valve, there is a problem that abrasion occurs due to sliding between a mating member such as a valve seat and a valve guide and each part of the valve, resulting in poor durability. For this reason, the titanium alloy valve is subjected to a finishing process in almost the same manner as the heat-resistant steel valve, and is Mo-sprayed in order to impart wear resistance to the shaft portion. Therefore, the manufacturing cost is high and the product is economically neglected.
【0004】一方、特開昭61−81505号公報、特
開昭62−256956号公報が提案しているように、
比較的安価な耐磨耗処理として各々の雰囲気で加熱する
酸化処理、窒化処理が知られている。しかし、通常のα
+β型チタン合金製バルブに、これらの処理を適用する
と、高い温度で加熱するために熱変形(特に軸部の曲
り)が生じ、バルブに要求される形状寸法精度を確保で
きない。従って、バルブとして使用するには、表面処理
を施したチタン合金製バルブを矯正することとなり、効
率的な生産が極めて困難となる。このことは「チタニウ
ム・ジルコニウム」vol.35、No.2、第74頁
に記載されている。On the other hand, as proposed in JP-A-61-81505 and JP-A-62-256956,
Oxidation treatment and nitriding treatment in which heating is performed in each atmosphere are known as relatively inexpensive abrasion-resistant treatments. But the normal α
When these treatments are applied to a + β type titanium alloy valve, it is heated at a high temperature, so that thermal deformation (particularly bending of the shaft portion) occurs, and the shape and dimension accuracy required for the valve cannot be secured. Therefore, in order to use it as a valve, the titanium alloy valve subjected to the surface treatment is corrected, which makes it extremely difficult to efficiently produce the valve. This means that "titanium zirconium" vol. 35, No. 2, page 74.
【0005】寸法形状変化が起こる原因は、通常のα+
β型チタン合金棒が微細な等軸α晶組織であるために、
酸化あるいは窒化の処理温度(700〜900℃)でチ
タン合金バルブが自重(約50g)によるわずかな応力
でクリープ変形するからである。 これに対して、特開
平5−59919号公報に記載される様に、特定の組織
(例えば針状α晶組織)のα+β型チタン合金や、ニア
α型チタン合金の棒をバルブ素材とすれば、このクリー
プ変形の問題は解決しうる。ところで、微細等軸α晶組
織の5〜10mmφの棒材は、熱間圧延後コイル状の線材
とし、冷間伸線により真円としたのち、シェービングに
より疵取りを行い、切断し、棒材に矯正するのが通例で
あるが、伸び値、絞り値の低下した針状α晶組織の棒材
の製造方法について具体的な提案はされていない。The cause of dimensional change is the usual α +
Since the β type titanium alloy rod has a fine equiaxed α crystal structure,
This is because the titanium alloy valve undergoes creep deformation at the oxidation or nitriding processing temperature (700 to 900 ° C.) with a slight stress due to its own weight (about 50 g). On the other hand, as described in JP-A-5-59919, if an α + β type titanium alloy having a specific structure (for example, a needle α crystal structure) or a rod of a near α type titanium alloy is used as a valve material. , The problem of creep deformation can be solved. By the way, a rod having a fine equiaxed α crystal structure with a diameter of 5 to 10 mmφ is formed into a coil-shaped wire rod after hot rolling, and after being drawn into a perfect circle by cold drawing, it is cut by shaving and cut into a rod material. However, no specific proposal has been made for a method for producing a rod having an acicular α-crystal structure with a reduced elongation value and reduced drawing value.
【0006】さらに、傘部の鍛造後に歪取り焼鈍を行う
が、チタン合金を使用した場合、クリープ変形のない特
定組織を有する素材でも、傘部の鍛造後の焼鈍時に軸部
が約100μmと大きく曲がる現象が生じる。素材が耐
熱鋼の場合、焼鈍処理により軸部に約50μmの曲りが
発生しているが、この変形分は容易に研削が可能である
ので問題と成っていない。しかし、チタン合金では軸部
の変形が大きく、そのために傘部の振れも大きくなり、
軸部および傘部の変形分を削ることとなるが、耐熱鋼と
比較して、切削、研削加工の能率が悪く、また素材コス
トが高いため、変形分を切削、研削する方法は、問題で
ある。Further, although strain relief annealing is performed after the forging of the umbrella portion, when a titanium alloy is used, even if the material has a specific structure without creep deformation, the shaft portion is as large as about 100 μm during the annealing after the forging of the umbrella portion. The phenomenon of bending occurs. When the material is heat-resisting steel, the annealing causes bending of the shaft portion of about 50 μm, but this deformation does not cause a problem because grinding can be easily performed. However, in titanium alloy, the deformation of the shaft part is large, so that the deflection of the umbrella part is also large,
Although the deformation of the shaft and the umbrella will be cut, compared to heat-resistant steel, the efficiency of cutting and grinding is poor, and the material cost is high, so the method of cutting and grinding the deformation is not a problem. is there.
【0007】[0007]
【発明が解決しようとする課題】本発明は、チタン合金
でバルブを製造する場合に、チタン合金棒材の製造方法
を改善することにより、後の酸化処理または窒化処理で
仕上げたバルブに変形が生じないために必要不可欠の工
程である傘部鍛造後の歪取り焼鈍で発生するバルブ粗形
材の軸部の曲りを小さくし、切削、研削必要量を少なく
しようとするものである。また上記歪取り焼鈍で発生す
る変形を防止する前提として、クリープ変形しにくい組
織を有する棒を製造する必要があるが、熱間加工工程で
クリープ変形しにくい針状α晶組織とすると、伸び値、
絞り値が低下するため、コイル状線材から棒材に矯正す
るときに割れやすくなり、これを防止する矯正方法が課
題となる。また熱間加工工程でクリープ変形しやすい微
細等軸α晶組織とすると、この組織をクリープ変形しに
くい組織に熱処理で変えるときに、熱処理中に大きく変
形してしまい矯正が困難となるため、これを防止する矯
正方法が課題である。SUMMARY OF THE INVENTION According to the present invention, when a valve is manufactured from a titanium alloy, by improving the method for manufacturing a titanium alloy rod, the valve finished by the subsequent oxidation treatment or nitriding treatment is not deformed. This is to reduce the amount of cutting and grinding required by reducing the bending of the shaft portion of the rough valve shaped material that occurs in the strain relief annealing after forging the umbrella portion, which is an indispensable step in order not to occur. Further, as a premise of preventing the deformation that occurs in the above strain relief annealing, it is necessary to manufacture a bar having a structure that is difficult to creep, but if the needle-shaped α crystal structure that is difficult to creep deform in the hot working step is used, the elongation value ,
Since the aperture value is lowered, the coiled wire is easily cracked when it is straightened, and a straightening method for preventing this is a problem. In addition, if a fine equiaxed α-crystal structure that easily undergoes creep deformation in the hot working process is used, when this structure is changed to a structure that is less likely to creep deformed by heat treatment, it will be greatly deformed during heat treatment, making correction difficult. The problem is a correction method to prevent this.
【0008】[0008]
【課題を解決するための手段】上記課題を解決するため
の本発明は、(1)チタン合金棒の製造において、コイ
ル状線材から直線状棒材に矯正する工程の内、少なくと
も最終工程にて700℃以上の熱間にて矯正することを
特徴とし、(2)上記(1)のチタン合金がα+β型チ
タン合金またはニアα型チタン合金であって、熱間加工
工程において針状α晶組織に調整されたコイル状線材で
ある場合には、粗矯正したのち、または、そのまま上記
(1)の方法により矯正することを特徴とし、(3)上
記(1)のチタン合金がα+β型チタン合金またはニア
α型チタン合金であって、熱間加工工程において微細等
軸α晶組織に調整されたコイル状線材である場合には、
粗矯正したのち、または、そのままβ変態点−50℃以
上、β変態点+100℃以下に加熱して微視組織を針状
α晶組織に等軸α晶が分散した組織または針状α晶組織
に調整したのち、上記(1)の方法により矯正すること
を特徴とする。According to the present invention for solving the above-mentioned problems, (1) in the production of a titanium alloy rod, at least in the final step among the steps of straightening a coiled wire into a straight rod. (2) The titanium alloy of (1) above is an α + β type titanium alloy or a near α type titanium alloy, and has a needle-like α crystal structure in the hot working step. In the case of a coiled wire adjusted to, the wire is roughly straightened or straightened by the method of (1), and (3) the titanium alloy of (1) is an α + β titanium alloy. Alternatively, in the case of a near α-type titanium alloy, which is a coiled wire rod adjusted to a fine equiaxed α crystal structure in the hot working step,
After being roughly corrected, or as it is, heated to a β transformation point of −50 ° C. or more and a β transformation point of + 100 ° C. or less, and the microscopic structure is a structure in which equiaxed α crystals are dispersed in a needle α crystal structure or a needle α crystal structure. It is characterized in that it is corrected by the method of the above (1) after the adjustment.
【0009】[0009]
【作用】以下、本発明を詳細に説明する。本発明に適し
たチタン合金は、α+β型チタン合金である、Ti−6
Al−4V、Ti−3Al−2.5V、Ti−6Al−
2Fe−0.1Si、Ti−5Al−1Fe、Ti−5
Al−2Cr−1Fe、Ti−6Al−2Sn−4Zr
−6Mo等、およびニアα型チタン合金である、Ti−
6Al−2Sn−4Zr−2Mo−0.1Si等であ
る。これらの合金は、熱間加工により直径5〜10mmの
線材が製造可能であるとともに、エンジンバルブとして
の使用特性を満足しうるものである。またこれらのチタ
ン合金は、β相温度域にて熱間加工するか、または単に
加熱すると、針状α晶組織となり、α+β相温度域にて
充分に熱間加工すると、微細等軸α晶組織となる。The present invention will be described in detail below. A titanium alloy suitable for the present invention is an α + β type titanium alloy, Ti-6.
Al-4V, Ti-3Al-2.5V, Ti-6Al-
2Fe-0.1Si, Ti-5Al-1Fe, Ti-5
Al-2Cr-1Fe, Ti-6Al-2Sn-4Zr
-6Mo, etc., and Ti-, which is a near α-type titanium alloy
6Al-2Sn-4Zr-2Mo-0.1Si and the like. These alloys are capable of producing wire rods having a diameter of 5 to 10 mm by hot working and satisfying the usage characteristics as an engine valve. Further, these titanium alloys have a needle-shaped α crystal structure when hot-worked in the β-phase temperature range or simply heated, and a fine equiaxed α-crystal structure when hot-worked sufficiently in the α + β-phase temperature range. Becomes
【0010】これらの合金のコイル状線材の段階での微
視組織がクリープ変形しにくい組織、すなわち針状α晶
組織である場合は、以下に示す方法により矯正を行う。
まずはじめに、コイルを連続抽伸機に通すかまたはその
まま適当な長さに切断したのち、割れ発生のない程度に
粗矯正を行う。針状組織の線材は、例えば、伸び値は7
%、絞り値は20%と通常の微細等軸α晶組織を持つ材
料の半分程度に小さくなっており、ちどり状に配置した
ロールによる通常の矯正方法(2ロール矯正)では、完
全に矯正すると割れが発生するため、粗矯正までに止め
ておく。なお次に述べる熱間矯正する設備を用いて粗矯
正を行っても良い。When the microscopic structure at the stage of the coiled wire rod of these alloys is a structure which is unlikely to undergo creep deformation, that is, a needle-shaped α-crystal structure, it is corrected by the following method.
First, the coil is passed through a continuous drawing machine or cut as it is to an appropriate length, and then rough correction is performed to such an extent that cracking does not occur. For example, a wire having a needle-like structure has an elongation value of 7
%, The aperture value is 20%, which is about half that of a material with a normal fine equiaxed α crystal structure. Since cracking will occur, stop before rough correction. Rough straightening may be performed using the hot straightening equipment described below.
【0011】次に、熱間で矯正するのは、冷間で矯正し
たままであると、後の傘部鍛造後の焼鈍で冷間での曲げ
加工で導入された歪が開放し、変形が発生するからであ
る。すなわち、通常バルブ用に使用される5〜10mmφ
の細い棒材は、ビレットを熱間圧延し、直径が1〜2m
のコイル状の線材とした後に、冷間伸線、シェービング
を行い表面を精整し、かつ断面を真円に近いものとす
る。つぎにコイルを連続抽伸機に通し、適当な長さに切
断後、冷間で2ロール矯正し直棒とし、センタレス研削
して仕上げられる。この冷間矯正時(冷間伸線時を含
む)に棒材に大きな歪が蓄積され、後の加熱により、元
の形状に少し戻る。Next, what is to be hot-corrected is that if it is left cold-corrected, the strain introduced by the cold bending during the subsequent annealing after the forging of the umbrella portion is released and the deformation is caused. This is because it occurs. That is, 5-10 mmφ which is usually used for valves
For the thin rod of, the billet is hot-rolled and the diameter is 1-2 m.
After forming the coiled wire, the surface is refined by cold drawing and shaving, and the cross section is close to a perfect circle. Next, the coil is passed through a continuous drawing machine, cut into an appropriate length, and then cold-rolled by 2 rolls to form a straight rod, and centerless grinding is performed for finishing. During this cold straightening (including cold drawing), a large amount of strain is accumulated in the bar material, and due to subsequent heating, it returns to its original shape.
【0012】熱処理時に冷間で導入された歪が棒材形状
に与える影響の一例を挙げると、Ti−6Al−4V合
金の場合、10cm当たり2.5mmの曲りを冷間で矯正す
ると、800℃の焼鈍により約4%、100μmの曲り
が発生する。一方バルブ用耐熱鋼SUH11の場合、同
様の曲りを冷間で矯正すると800℃の焼鈍により約2
%、50μmの曲りを生じるにすぎない。To give an example of the influence of the strain introduced in the cold during the heat treatment on the shape of the bar material, in the case of Ti-6Al-4V alloy, if the bending of 2.5 mm per 10 cm is straightened in the cold, 800 ° C. Bending of about 4% or 100 μm occurs due to the annealing. On the other hand, in the case of the valve heat resistant steel SUH11, if the same bending is straightened cold, it will be about 2 by annealing at 800 ℃.
%, Only a bend of 50 μm occurs.
【0013】熱間矯正の方法は、通電加熱により材料の
温度を高くしたのち、引張応力を加えて直線状に矯正す
るのが一般的である。ここで熱間で矯正する温度を70
0℃以上としたのは、700℃未満の温度で矯正した棒
材は、傘部鍛造後の焼鈍で軸部に曲りがでるためであ
る。ここで軸部が曲がらないように700℃未満で焼鈍
することも考えられるが、後の耐磨耗処理温度も700
℃未満に制限される。その結果、窒化処理と比べて処理
温度の低い酸化処理を行う場合でも、700℃未満の処
理では硬化層の付与が不十分であり、特にフェース部の
耐磨耗性が不足する。ここでは熱間矯正の上限の温度は
特に定めないが、温度が高すぎると耐力が低くなるた
め、重力で線材が垂れ下がり、両端からの引張応力を加
えるだけでは矯正の効果が十分でない場合がある。この
ことと、傘部鍛造後の焼鈍で軸部に曲りが出なくなる温
度を考え合わせると、矯正温度は700〜900℃が好
ましい。なお加熱時間が短い場合は、温度を多少高めに
する必要がある。また冷却は空冷で良い。In the hot straightening method, generally, the temperature of the material is raised by electric heating, and then tensile stress is applied to straighten it. Here, the temperature for straightening hot is 70
The reason why the temperature is set to 0 ° C. or higher is that the rod material straightened at a temperature lower than 700 ° C. is bent in the shaft portion by annealing after the forging of the umbrella portion. Here, it may be possible to anneal below 700 ° C so that the shaft does not bend, but the subsequent abrasion resistance treatment temperature is 700
Limited to less than ℃. As a result, even when the oxidation treatment is performed at a treatment temperature lower than that of the nitriding treatment, the treatment at a temperature of less than 700 ° C. does not sufficiently impart the hardened layer, and particularly the wear resistance of the face portion is insufficient. Although the upper limit temperature for hot straightening is not specified here, if the temperature is too high, the yield strength will decrease, so the wire rod hangs due to gravity, and the effect of straightening may not be sufficient just by applying tensile stress from both ends. . Considering this and the temperature at which the shaft portion does not bend due to annealing after forging the umbrella portion, the straightening temperature is preferably 700 to 900 ° C. When the heating time is short, it is necessary to raise the temperature somewhat. Further, cooling may be air cooling.
【0014】バルブ用のチタン合金が、コイル状線材の
段階でクリープ変形しやすい粒径が2〜4μmの微細等
軸α晶組織をもつ場合は、以下に示す方法により矯正を
行う。まずはじめに、コイルを連続抽伸機に通し、適当
な長さに切断したのち、必要に応じて通常のちどり状に
配置したロール等により粗矯正する。なおこの線材は、
伸び値は15%、絞り値は40%と大きいので完全に矯
正を行っても割れの問題はない。次に熱間矯正する設備
を用いて、熱間矯正前に、β変態点−50℃以上から、
β変態点未満の温度に加熱したのちに矯正温度まで空冷
し、針状α晶組織の中に等軸α晶が分散した組織に変え
るか、または熱間矯正前に、β変態点以上、β変態点+
100℃以下の温度に加熱したのちに矯正温度まで空冷
し、針状α晶組織に変えた後に熱間矯正を行う。このよ
うに組織を変えるのは、傘部鍛造後の焼鈍および耐磨耗
処理での加熱時にクリープ変形しにくくするためであ
る。さらに通常の熱処理炉を使用しないのは、クリープ
変形しやすい微細等軸α晶組織のコイル状の線材を加熱
炉中で処理すると大きく変形し、後の矯正が困難となる
からである。なお、この組織調整のための熱処理後、室
温まで空冷したのち、再度所定の温度まであげて矯正し
てももちろん良い。When the titanium alloy for a valve has a fine equiaxed α-crystal structure with a grain size of 2 to 4 μm, which easily undergoes creep deformation at the stage of coiled wire, it is corrected by the following method. First, the coil is passed through a continuous drawing machine to be cut into an appropriate length, and if necessary, roughly corrected by a roll or the like arranged in a usual birdlike shape. In addition, this wire rod
Since the elongation value is as large as 15% and the drawing value is as large as 40%, there is no problem of cracking even if it is completely straightened. Next, using a facility for hot straightening, before the hot straightening, from the β transformation point of -50 ° C or higher,
After heating to a temperature below the β transformation point, it is air-cooled to the straightening temperature and changed into a structure in which equiaxed α crystal structure has equiaxed α crystals dispersed, or before hot correction, β transformation point or more, β Transformation point +
After being heated to a temperature of 100 ° C. or lower, it is air-cooled to a straightening temperature and converted into a needle-shaped α crystal structure, and then hot straightening is performed. The reason for changing the structure in this way is to make it difficult for creep deformation during annealing and heat treatment during abrasion resistance after forging. Furthermore, the reason why a normal heat treatment furnace is not used is that if a coil-shaped wire rod having a fine equiaxed α-crystal structure that is susceptible to creep deformation is treated in a heating furnace, it is greatly deformed, and it becomes difficult to correct it later. Of course, after the heat treatment for adjusting the structure, it may be air-cooled to room temperature and then raised again to a predetermined temperature to correct it.
【0015】ここでβ変態点−50℃以上としたのは、
この温度未満では、微細な等軸α晶組織からの変化は少
なく、クリープ変形を防止する効果が少ないためであ
る。またβ変態点+100℃以下としたのは、この温度
を越える場合は、クリープ変形を防止する効果は充分発
揮できるが、酸化が激しくなり、後工程でのセンターレ
ス加工において研削代が多く必要となるからである。な
お組織の調整に必要な加熱時間は、β変態点以下の場合
は、数分から30分であり、β変態点以上の場合は数秒
から1分程度である。Here, the β transformation point of -50 ° C. or higher is
This is because below this temperature, the change from the fine equiaxed α-crystal structure is small and the effect of preventing creep deformation is small. The β transformation point + 100 ° C. or lower means that when the temperature is higher than this, the effect of preventing creep deformation can be sufficiently exerted, but oxidation becomes severe and a large grinding allowance is required in the centerless processing in the post process. Because it will be. The heating time necessary for adjusting the structure is from several minutes to 30 minutes when the temperature is below the β transformation point, and from several seconds to 1 minute when it is above the β transformation point.
【0016】[0016]
【実施例1】Ti−6Al−4Vビレットをβ相温度域
にて熱間加工により9mmφの線材とした。コイルの巻き
取り直径は約1mであり、この材料の微視組織は針状α
晶組織である。Example 1 A Ti-6Al-4V billet was hot-worked in a β-phase temperature range to obtain a wire having a diameter of 9 mm. The winding diameter of the coil is about 1 m, and the microstructure of this material is needle-like α.
It has a crystal structure.
【0017】この線材を、冷間伸線とシェービングを行
い、表面を精整するとともに直径7mmの真円とした。こ
の一部を通常のちどり状に配置したロールにより、割れ
防止のために200℃にて矯正し、その他を粗矯正した
のち、600〜900℃の各温度で通電加熱しながら引
張る方法で熱間矯正した。それぞれをセンターレス研削
により6.7mmφの曲りのない棒材とし、さらに所定の
方法により傘部を鍛造し、傘径36mm、バルブ長さ11
5mmのバルブ粗形材としたのち、600〜900℃で1
時間バルブを横に寝かせた状態で焼鈍した。以上の工程
を経た後に、バルブ粗形材の軸部に発生した曲り、すな
わち片面当たりのセンターレス研削必要量を測定した結
果を表1に示す。This wire rod was subjected to cold drawing and shaving to refine the surface and make a true circle having a diameter of 7 mm. This part is straightened at a temperature of 200 ° C to prevent cracking with a roll arranged in a normal dust-like shape, and the other parts are roughly straightened, and then hot drawn by a method of pulling while energizing at each temperature of 600 to 900 ° C. I corrected it. Each of them was made centerless ground into a bar material of 6.7 mmφ without bending, and the umbrella part was forged by a predetermined method, and the umbrella diameter was 36 mm and the valve length was 11 mm.
After making a 5mm valve rough material, 1 at 600-900 ℃
Annealing was performed with the time valve lying sideways. Table 1 shows the results of measuring the bending generated in the shaft portion of the rough valve material after the above steps, that is, the required amount of centerless grinding per one surface.
【0018】軸部の曲りは、軸部の両端を支持してバル
ブを回転し、ダイヤルゲージにて中央部の振れの最小値
と最大値を測定し、この差の半分とした。これによると
700℃以上の温度で矯正することで、後の加熱で発生
する曲りの94%を除去することが出来るのでバルブ加
工でのセンターレス研削必要量を激減しうる。一方、6
00℃での矯正は、50%の除去にすぎない。なお85
0〜900℃の焼鈍では、クリープによる変形が少し生
じている。次に、傘径35mm、バルブ長さ110mm、軸
径6.68mmの最終バルブ形状に仕上げた後、700〜
900℃で1時間バルブを横に寝かせた状態および立脚
させた状態で酸化処理した結果を表2に示す。本発明で
製造されたチタン合金棒は傘部鍛造後の焼鈍での軸部の
曲りが少ないので、バルブ加工でのセンターレス研削必
要量が極めて少ないこと、酸化処理で適正な温度やバル
ブの設置状態を選択することで、寸法精度が高いバルブ
を製造しうることが分かる。ここで、バルブに要求され
る寸法精度では10μm以内である。また、焼鈍後に曲
りの少ないものは、少なくとも軸部については熱間矯正
工程で焼鈍の役目が終了しているので、傘鍛造を高温で
行い歪の残留しないようにすれば、焼鈍工程を省略でき
る。すなわち、鍛造、仕上げ加工した後に直接酸化処理
を実施してよい。For the bending of the shaft portion, the valve was rotated while supporting both ends of the shaft portion, and the minimum and maximum values of the shake of the central portion were measured with a dial gauge, and the difference was set to half the difference. According to this, by straightening at a temperature of 700 ° C. or higher, it is possible to remove 94% of the bending generated by the subsequent heating, so that the required amount of centerless grinding in valve processing can be drastically reduced. On the other hand, 6
Straightening at 00 ° C is only 50% removal. 85
When annealed at 0 to 900 ° C, some deformation due to creep occurs. Next, after finishing the final valve shape with umbrella diameter 35mm, valve length 110mm, and shaft diameter 6.68mm, 700 ~
Table 2 shows the results of the oxidation treatment at 900 ° C. for 1 hour with the valve lying sideways and in a standing state. The titanium alloy rod manufactured according to the present invention has little bending of the shaft during annealing after the forging of the umbrella, so that the amount of centerless grinding required for valve processing is extremely small, and an appropriate temperature and valve can be installed by oxidation treatment. By selecting the state, it can be seen that a valve with high dimensional accuracy can be manufactured. Here, the dimensional accuracy required for the valve is within 10 μm. Also, for those with little bending after annealing, since the role of annealing has been completed in the hot straightening step at least for the shaft portion, the annealing step can be omitted if umbrella forging is performed at high temperature so that no strain remains. . That is, the oxidation treatment may be performed directly after the forging and finishing.
【0019】[0019]
【表1】 [Table 1]
【0020】[0020]
【表2】 [Table 2]
【0021】[0021]
【実施例2】Ti−6Al−4Vビレットを熱間加工に
より9mmφの線材とした。コイルの巻き取り直径は約1
mであり、この材料の微視組織は針状α晶組織である。
工程1として、この線材を、冷間伸線とシェービングを
行い、表面疵を除去するとともに直径7.9mmの真円と
し、この一部を連続抽伸を行って7.6mmφの棒材とし
た。2ロール矯正を、ロールオフセット量を10mmで行
ったところ、棒の曲りは完全に除去できた。その後セン
タレス研削により7.3mmφの磨棒に加工して、浸透探
傷試験を行ったところ、図5に示すC方向疵が30%発
生した。次にロールオフセット量を7mmで行ったとこ
ろ、曲り不良が10%、C方向疵が15%発生した。さ
らに、ロールオフセット量を5mmで行ったところ、曲り
不良が20%、C方向疵が10%発生した。結果を表3
に示す。ここで、棒の長さ1m当り0.25mm超の曲り
のものを、曲り不良とした。Example 2 A Ti-6Al-4V billet was hot worked into a wire rod having a diameter of 9 mm. The coil winding diameter is about 1
m, and the microstructure of this material is an acicular α-crystal structure.
In step 1, this wire rod was subjected to cold drawing and shaving to remove surface flaws and form a perfect circle having a diameter of 7.9 mm, and a part of this was drawn continuously to obtain a 7.6 mmφ rod. When two-roll straightening was performed with a roll offset amount of 10 mm, the bending of the bar could be completely removed. After that, a 7.3 mmφ polishing rod was processed by centerless grinding and a penetrant flaw detection test was carried out. As a result, 30% of C-direction flaws shown in FIG. Next, when the roll offset amount was set to 7 mm, the bending defect was 10% and the C-direction flaw was 15%. Further, when the roll offset amount was set to 5 mm, the bending defect was 20% and the C-direction flaw was 10%. The results are shown in Table 3.
Shown in. Here, a bent rod having a bending length of more than 0.25 mm per 1 m was regarded as a defective bending.
【0022】工程2として、上記直径7.9mmφの真円
材を用いて、連続抽伸を行って7.6mmφの棒材とし、
700〜1000℃の各温度で通電加熱しながら引張る
熱間矯正を行って、棒の曲りを除去した後、センタレス
研削により7.3mmφの磨棒とした。この磨棒の浸透探
傷試験を行ったところ、外面疵は発生しなかった。工程
3として、上記圧延材を冷間伸線とシェービングを行
い、7.6mmφの真円材とし、線材のまま700〜10
00℃の各温度で通電加熱しながら引張る熱間矯正を行
って、曲りのない棒とした後、センタレス研削により
7.3mmφの磨棒とした。この磨棒の浸透探傷試験を行
ったところ、外面疵は発生しなかった。In step 2, using the above-mentioned perfect circular material having a diameter of 7.9 mmφ, continuous drawing is carried out to obtain a bar material having a diameter of 7.6 mmφ.
After performing hot straightening by pulling while electrically heating at each temperature of 700 to 1000 ° C. to remove bending of the rod, centerless grinding was performed to obtain a polished rod of 7.3 mmφ. When a penetrant flaw detection test was performed on this polishing rod, no external flaw was generated. In step 3, the rolled material is subjected to cold drawing and shaving to form a 7.6 mmφ round material, and the wire material is 700 to 10 as it is.
Hot-rectification was performed by pulling while heating by energization at each temperature of 00 ° C. to obtain a rod without bending, and then centerless grinding was performed to obtain a polished rod of 7.3 mmφ. When a penetrant flaw detection test was performed on this polishing rod, no external flaw was generated.
【0023】表4に製造工程を、表5に浸透探傷試験結
果を示す。以上により、熱間矯正を行うことにより、曲
り不良のない、また、外面疵のない直棒を高い歩留で製
造することができる。Table 4 shows the manufacturing process, and Table 5 shows the results of the penetrant inspection test. As described above, by carrying out hot straightening, it is possible to manufacture a straight rod having no bending defect and no external flaw with a high yield.
【0024】[0024]
【表3】 [Table 3]
【0025】[0025]
【表4】 [Table 4]
【0026】[0026]
【表5】 [Table 5]
【0027】[0027]
【実施例3】準備したチタン合金は、コイル状線材であ
り、その種類は、2〜4μm粒の等軸α晶組織を有する
Ti−6Al−4VとTi−3Al−2.5V、および
2〜4μm幅の針状α晶を有するTi−6Al−4Vと
Ti−3Al−2.5V、Ti−6Al−2Fe−0.
1Si、Ti−5Al−1Fe、Ti−5Al−2Cr
−1Fe、Ti−6Al−2Sn−4Zr−6Mo、T
i−6Al−2Sn−4Zr−2Mo−0.1Siであ
る。Example 3 The prepared titanium alloy is a coil-shaped wire, and the types thereof are Ti-6Al-4V and Ti-3Al-2.5V having an equiaxed α crystal structure of 2 to 4 μm grains, and 2 to Ti-6Al-4V, Ti-3Al-2.5V, and Ti-6Al-2Fe-0.
1Si, Ti-5Al-1Fe, Ti-5Al-2Cr
-1Fe, Ti-6Al-2Sn-4Zr-6Mo, T
i-6Al-2Sn-4Zr-2Mo-0.1Si.
【0028】これらに本発明の方法を適用した。例え
ば、2〜4μm粒の等軸α晶組織のものは、熱間矯正前
に微視組織を変えるため同設備を用いて通電により加熱
し、その後矯正温度まで空冷し、矯正した。これらの棒
材をセンターレス研削後、バルブに加工した。すなわち
傘部鍛造、焼鈍、仕上げ加工し、酸化処理を施した。The method of the present invention was applied to these. For example, the one having an equiaxed α-crystal structure of 2 to 4 μm grains was heated by energization using the same equipment to change the microstructure before hot correction, and then air-cooled to the correction temperature for correction. These rods were processed into valves after centerless grinding. That is, the umbrella portion was forged, annealed, finished, and oxidized.
【0029】表6に処理工程と各工程終了後の軸部の曲
りを示す。傘部鍛造後の焼鈍では、バルブ粗形材を横に
寝かせた状態で1時間大気炉加熱した。酸化処理は、バ
ルブを立脚された状態で大気炉加熱した。本発明の方法
によれば、焼鈍後の軸部の曲りが13μm以内と極めて
少ないことが分かり、研削必要量を減少させることがで
きる。Table 6 shows the processing steps and the bending of the shaft after each step. In the annealing after the forging of the umbrella portion, the rough valve material was laid sideways and heated in an atmospheric furnace for 1 hour. For the oxidation treatment, the atmosphere furnace was heated with the valve standing. According to the method of the present invention, it was found that the bending of the shaft portion after annealing was extremely small within 13 μm, and the required grinding amount could be reduced.
【0030】[0030]
【表6】 [Table 6]
【0031】[0031]
【発明の効果】本発明を用いることにより、伸び値、絞
り値の小さく、クリープ変形しにくい棒材を効率的に製
造できる。さらにバルブ製造工程において、型鍛造後の
軸部の曲りが極めて少ないため、軸部の切削代を少なく
出来る。その結果、製造コストが低減できる一例を表7
に示す。EFFECTS OF THE INVENTION By using the present invention, it is possible to efficiently manufacture a bar material having a small elongation value and drawing value and being resistant to creep deformation. Further, in the valve manufacturing process, since the bending of the shaft portion after die forging is extremely small, the cutting allowance of the shaft portion can be reduced. As a result, Table 7 shows an example in which the manufacturing cost can be reduced.
Shown in.
【0032】[0032]
【表7】 [Table 7]
【0033】本発明を適用した結果、バルブ軸部に対す
る素材コストの約1割、切削費用の9割以上が低減しう
る。また軸部の曲りは傘部の振れにも影響し、その部分
の研削代も多くする必要があったが、本発明によりこれ
についても大幅な改善ができる。As a result of applying the present invention, about 10% of the material cost for the valve shaft portion and 90% or more of the cutting cost can be reduced. Further, the bending of the shaft portion also affects the deflection of the umbrella portion, and it is necessary to increase the grinding allowance of that portion, but the present invention can greatly improve this.
【図1】バルブ側面図。FIG. 1 is a side view of a valve.
【図2】バルブ粗形材の軸部が変形した状態の例を示す
図。FIG. 2 is a diagram showing an example of a state in which a shaft portion of a rough valve material is deformed.
【図3】バルブを横に寝かせた状態を示す図。FIG. 3 is a view showing a state in which the valve is laid sideways.
【図4】バルブを立脚させた状態を示す図。FIG. 4 is a view showing a state in which the valve is stood.
【図5】バルブ材におけるC方向疵を示す図。FIG. 5 is a diagram showing a C-direction flaw in a valve material.
1:傘部 2:軸部 3:軸端部 4:フェース部 1: Umbrella part 2: Shaft part 3: Shaft end part 4: Face part
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山本 諭 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 (72)発明者 左田野 豊 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 (72)発明者 大黒 治男 山口県光市大字島田3434番地 新日本製鐵 株式会社光製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoshi Yamamoto Satoshi Yamaguchi 3434 Shimada, Hikari City Yamaguchi Prefecture Inside the Nippon Steel Co., Ltd. Hikari Steel Works (72) Inventor Satano Toyoguchi 3434 Shimada, Hikari City Shimada Prefecture New Japan (90) Haruo Oguro Inventor Haruo Oguro No. 3434 Shimada, Hikari City, Yamaguchi Prefecture Nippon Steel Works Hikari Steel Co., Ltd.
Claims (3)
線材から直線状棒材に矯正する工程の内、少なくとも最
終工程にて700℃以上の熱間にて矯正することを特徴
とするエンジンバルブの製造に適したチタン合金棒の製
造方法。1. In the production of a titanium alloy rod, in the step of straightening a coil-shaped wire into a straight rod, at least in the final step, straightening is performed by heat of 700 ° C. or higher. A method for manufacturing a titanium alloy rod suitable for manufacturing.
タン合金またはニアα型チタン合金であって、熱間加工
工程において針状α晶組織に調整されたコイル状線材で
ある場合には、粗矯正したのち、または、そのまま請求
項1記載の方法により矯正することを特徴とするエンジ
ンバルブの製造に適したチタン合金棒の製造方法。2. When the titanium alloy according to claim 1 is an α + β type titanium alloy or a near α type titanium alloy and is a coiled wire rod adjusted to an acicular α crystal structure in the hot working step, A method for manufacturing a titanium alloy rod suitable for manufacturing an engine valve, which comprises roughening or straightening by the method according to claim 1.
タン合金またはニアα型チタン合金であって、熱間加工
工程において微細等軸α晶組織に調整されたコイル状線
材である場合には、粗矯正したのち、または、そのまま
β変態点−50℃以上、β変態点+100℃以下に加熱
して微視組織を針状α晶組織に等軸α晶が分散した組織
または針状α晶組織に調整したのち、請求項1記載の方
法により矯正することを特徴とするエンジンバルブの製
造に適したチタン合金棒の製造方法。3. When the titanium alloy according to claim 1 is an α + β type titanium alloy or a near α type titanium alloy, which is a coiled wire rod adjusted to a fine equiaxed α crystal structure in the hot working step. After rough correction, or after being directly heated to a β transformation point of −50 ° C. or higher and a β transformation point of + 100 ° C. or lower, the microscopic structure is a structure in which equiaxed α crystals are dispersed in equiaxed α crystals or needle α crystals. A method for manufacturing a titanium alloy rod suitable for manufacturing an engine valve, which comprises adjusting the structure and then straightening it by the method according to claim 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19492293A JPH0748659A (en) | 1993-08-05 | 1993-08-05 | Production of titanium alloy bar suitable for production of engine valve |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP19492293A JPH0748659A (en) | 1993-08-05 | 1993-08-05 | Production of titanium alloy bar suitable for production of engine valve |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0748659A true JPH0748659A (en) | 1995-02-21 |
Family
ID=16332580
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP19492293A Withdrawn JPH0748659A (en) | 1993-08-05 | 1993-08-05 | Production of titanium alloy bar suitable for production of engine valve |
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CN106968744A (en) * | 2017-05-24 | 2017-07-21 | 崔旺林 | A kind of internal combustion engine inlet valve |
JP2018053313A (en) * | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | α+β TYPE TITANIUM ALLOY BAR AND MANUFACTURING METHOD THEREFOR |
CN114178339A (en) * | 2021-12-09 | 2022-03-15 | 宁夏中色金航钛业有限公司 | Fine-grain Ti for 3D printing additive powder making2AlNb alloy bar and preparation method thereof |
-
1993
- 1993-08-05 JP JP19492293A patent/JPH0748659A/en not_active Withdrawn
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JP2018053313A (en) * | 2016-09-29 | 2018-04-05 | 新日鐵住金株式会社 | α+β TYPE TITANIUM ALLOY BAR AND MANUFACTURING METHOD THEREFOR |
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CN106968744B (en) * | 2017-05-24 | 2019-04-12 | 泰州市龙瑞阀业有限公司 | A kind of internal combustion engine inlet valve |
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