JP3680651B2 - Manufacturing method of integral crankshaft - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、鍛造によって製造される一体形クランク軸の製造方法に関し、詳しくは、対向する２つの型での型押しによる素材フロント相当部の圧下、曲げ打ち、荒打ち、仕上げ打ち及びバリ抜きの各工程を経る一体形クランク軸の製造方法に関する。
【０００２】
【従来の技術】
自動車などのクランク軸は、従来、鋳造や鍛造によって製造されてきた。しかし、近年、エンジンの軽量化や高出力化が進むにともない、クランク軸には高強度、高靱性が要求されるようになり、鍛造で製造される一体形クランク軸の需要が高まっている。
【０００３】
鍛造で製造される一体形クランク軸（以下、「製品」ともいう）は、機械構造用炭素鋼や合金鋼の角ビレットや丸ビレットを素材として、例えば、▲１▼ロール成形、▲２▼曲げ打ち（曲げ加工）、▲３▼荒打ち（型鍛造の第１工程）、▲４▼仕上げ打ち（型鍛造の第２工程）、▲５▼バリ抜き（バリ取り）の各工程を経て成形されてきた。なお、一般に、ロール成形と曲げ打ちを経て成形された被鍛造材は、曲げ打ち時の姿勢に対して軸回りに９０度回転させた姿勢で荒打ちに供される。
【０００４】
上記▲１▼〜▲５▼の工程のうち、▲１▼のロール成形は、凹凸を有するロールによる圧延成形工程で、素材（被鍛造材）の各部位の断面積を調整することで、軸方向に体積配分を行う処理である。すなわち、このロール成形は、素材の製品フロント部に相当する部位を、製品のフロント部に近い断面積を有する細長い形状に延伸し、フロント部近傍の歩留りを高めようとするものである。
【０００５】
しかし、ロールで圧延する場合、被加工材の表面が内部より延びやすい。このため、ロールで成形した後の製品フロント部に相当する部位の端面は、後述の図１（ｂ）に示すような中央が凹んだ形状になることが多く、これを▲３▼に示した荒打ちに供した場合には、前記端面が内部に折り込まれて疵が発生する。こうした疵が製品部分に生じると不良品となってしまう。したがって、従来は、予め荒打ち前の被鍛造材の製品フロント部に相当する部位を長めに加工して「捨て代」として確保し、前記の疵が「捨て代」に入るようにして製品内に残存しないように調整されていた。このため、ロール成形で被鍛造材を加工する場合、フロント部の歩留りが低くなることを避けられなかった。
【０００６】
特開平２−２５５２４０号公報に、ロール荒地の断面積分布を製品クランク軸の断面積分布に近付けることで、ロール成形時の歩留まり向上が可能な「型鍛造クランク軸の荒地取り方法」が開示されている。しかし、この公報で提案された技術もロール成形であることには変わりがないので、前記した製品フロント部に相当する部位の端面には凹みが生じることを完全には避けられず、したがって、製品部分に疵が入るのを防ぐために捨て代が必要となり、フロント部の歩留まりはやはり低いものであった。
【０００７】
【発明が解決しようとする課題】
本発明は、上記現状に鑑みなされたもので、その目的は、一体形クランク軸のフロント部に相当する部位の端面に凹みを生じさせることがなく、フロント部歩留まりを高めることができる一体形クランク軸の製造方法を提供することである。なお、以下の説明において、一体形クランク軸を単に「クランク軸」ともいう。
【０００８】
【課題を解決するための手段】
本発明の要旨は、下記の（１）及び（２）に示す一体形クランク軸の製造方法にある。
【０００９】
すなわち、
「（１）対向する２つの型での型押しによる素材フロント相当部の圧下、曲げ打ち、荒打ち、仕上げ打ち及びバリ抜きの各工程を経る一体形クランク軸の製造方法であって、前記対向する２つの型での型押しによる素材フロント相当部の圧下によって一体形クランク軸鍛造荒地を製造する際に、素材のフロント相当部を、素材の軸方向に垂直な方向に厚みが素材厚みの８０〜３５％になるように圧下することを特徴とする一体形クランク軸の製造方法。」
「（２）上記（１）に記載の一体形クランク軸の製造方法であって、一体形クランク軸鍛造荒地を製造する際に、対向する２つの型での型押しによる素材フロント相当部の圧下と曲げ打ちを同時に行うことを特徴とする一体形クランク軸の製造方法。」
である
【００１０】
なお、「鍛造荒地」とは型鍛造の第１工程である荒打ちに供される被鍛造材を指す。又、既に述べた「一体形クランク軸のフロント部」とは、クランク軸の軸方向端部の一方をいい、その形状は円柱形で他の部位に比較して軸に垂直な断面での断面積が小さい。
なお、素材の「フロント相当部」とは、製品クランク軸のフロント部になる素材の部分を指す。そして、素材の「フロント相当部」以外の部分を「非フロント相当部」ということにする。
【００１１】
素材の「軸方向」とは図１（ａ）のＸ−Ｘ方向、つまり、素材の長さ方向をいい、「厚み」とは、軸方向に垂直な断面における圧下方向での最大寸法のことをいう。
【００１２】
本発明者らは、前記の課題を解決するために、図２に示すような形状の４気筒用のピン数が４である８枚カウンターウェイト品クランク軸を対象とした基礎実験を行った。
【００１３】
すなわち、先ず、従来サイズのＪＩＳ規格Ｓ４５Ｃの角ビレットを素材として、通常の方法でロール成形、曲げ打ち、荒打ち及び仕上げ打ちを行った。
【００１４】
図１（ａ）に素材である角ビレットの形状を示す。前記角ビレットをロール成形した後の形状は、図１（ｂ）に示すように、素材の角ビレットと同じ断面を有する部分（以下、「太胴部」という）、製品クランク軸のフロント部に相当する部位（以下、「細胴部」という）及び太胴部と細胴部をつなぐテーパ部で構成されていた。なお、「細胴部」端面は中央が凹んだ形状であった。これに曲げ打ちと荒打ちを行い、最後に仕上げ打ちを施した後のクランク軸のフロント部は、主に、上記ロール成形後の「細胴部」とテーパ部の材料で構成されていた。
【００１６】
上記従来サイズのＪＩＳ規格Ｓ４５Ｃの角ビレットを素材として、通常の方法でロール成形、曲げ打ち、荒打ち及び仕上げ打ちを行った製品のフロント部には疵や、欠肉と呼ばれる未充満部は生じなかった。
【００１７】
次に、断面形状は前記従来サイズの角ビレットと同じであるが、フロント相当部の長さを種々に変化させたものを素材として、通常の方法でロール成形、曲げ打ち、荒打ち及び仕上げ打ちを行った。この場合も「細胴部」端面は中央が凹んだ形状であった。このフロント相当部の長さを種々に変化させた実験から、素材となるビレットのフロント相当部の体積が各断面形状に対して特定の値（以下、この特定の値をＶＲという）未満の場合には、仕上げ打ち後の製品フロント部に、ロール成形で生じた中央の凹んだ端面の折れ込みに起因する疵が発生することがわかった。
【００１８】
更に、断面形状は前記従来サイズの角ビレットと同じで、フロント相当部の長さを種々に変化させたものを素材として、ロール成形に代えて、素材の軸方向に垂直な方向にフロント相当部に厚みが素材厚みの６０％になるように型押しによる圧下を加え、次いで、非フロント相当部に通常の曲げ打ちを行い、その後、通常の方法で荒打ちと仕上げ打ちする実験も行った。この場合、図１（ｃ）に示すように、「細胴部」端面には中央の凹みは生じなかったので、仕上げ打ち後の製品フロント部にも、ロール成形した場合に見られるような中央の凹んだ端面の折れ込みに起因する疵は発生しなかった。但し、素材となるビレットのフロント相当部の体積が特定の値（以下、この特定の値をＶＮという）未満の場合には、製品フロント部に欠肉が発生することがわかった。
【００１９】
なお、「ＶＲ」と、上記のフロント相当部に厚みが素材厚みの６０％になるように型押しで圧下した場合の「ＶＮ」とを比較すると、ＶＲ＞ＶＮであった。このことから、上記の条件で型押しすれば、ロール成形する場合に比べてフロント部分の歩留りを大きくできることもわかった。
【００２０】
そこで更に、断面形状は前記従来サイズの角ビレットと同じで、フロント相当部の長さを種々に変化させたものを素材として、ロール成形に代えて、素材の軸方向に垂直な方向にフロント相当部に厚みが素材厚みの種々の割合になるように型押しによる圧下を加え、次いで、非フロント相当部に通常の曲げ打ちを行い、その後、通常の方法で荒打ちと仕上げ打ちする実験も行った。この実験から、次の事項が明らかになった。
【００２１】
（ａ）素材の軸方向に垂直な方向にフロント相当部を型押しで圧下（以下、単に「素材フロント相当部の型押しによる圧下」という）した場合、圧下後のフロント相当部の厚みが素材厚みの８０〜３５％であれば、製品フロント部に欠肉が生じないために最低限必要なフロント相当部の体積ＶＮは、前記ＶＲ以下となる。
【００２２】
（ｂ）素材フロント相当部の型押しによる圧下で、圧下後のフロント相当部の厚みが素材厚みの８０％を超えれば、製品フロント部に欠肉が生じないために最低限必要なフロント相当部の体積ＶＮは、却って前記ＶＲよりも大きくなる。
【００２３】
（ｃ）素材フロント相当部の型押しによる圧下で、圧下後のフロント相当部の厚みが素材厚みの３５％未満となれば、荒打ちの際にフロント相当部に座屈が生じ、そのため製品フロント部に疵が生じる。
【００２４】
なお、前記の座屈は、素材フロント相当部に圧下を加えた後の扁平度が大きくなりすぎ、曲げ打ち後、軸回りに９０度回転して荒打ち金型上に配置すると、フロント相当部の高さが幅に比べて大きくなりすぎることに基づく。
【００２５】
上記（ａ）〜（ｃ）から、素材のフロント相当部に、素材の軸方向に垂直な方向に厚みが素材厚みの８０〜３５％になるように型押しによる圧下を加えることで、通常のロール成形の場合よりもフロント部の歩留まりを高くできることが判明した。
【００２６】
本発明は、上記の知見に基づいて完成されたものである。
【００２７】
【発明の実施の形態】
以下に、本発明の詳細を説明する。
【００２８】
先ず、通常の方法で溶製した鋼塊から通常の方法で素材ビレットを製造する。なお、素材ビレットの断面サイズは、通常のロール成形を行う場合、つまりレデュースロールで軸絞りを加えて製造する場合の、レデュースロールによる軸絞りを行った後の鋼材の非フロント相当部の断面と同程度のものとすればよい。
【００２９】
次に、この素材のフロント相当部に、対向する２つの型によって、素材の軸方向に垂直な方向に厚みが素材厚みの８０〜３５％になるように圧下を加えて成形する。この後、通常の方法で、曲げ打ち、荒打ち、仕上げ打ちを行い、更にバリ抜きを行う。なお、対向する２つの型による前記の素材フロント相当部の圧下と曲げ打ちを同時に行ってもよい。
【００３０】
上記の方法によれば、ロール成形後に曲げ打ち、荒打ち、仕上げ打ちを行い、更にバリ抜きを行う通常の製造方法による場合に比べて、フロント部の歩留りを高めることができる。
【００３１】
なお、前記圧下後の厚みが素材厚みの８０％を超える場合、製品フロント部に欠肉を生じさせないために最低限必要なフロント相当部の体積が、却って従来のロール成形で疵を生じさせないために最低限必要なフロント相当部の体積よりも大きくなって歩留りを高めることができない。一方、前記圧下後の厚みが素材厚みの３５％未満の場合には、フロント相当部に座屈が生じ、そのため製品フロント部に疵が生じてしまう。
【００３２】
圧下後の厚みが素材厚みの８０〜３５％でありさえすれば、素材の軸方向に垂直な方向に圧下を加えた後の断面形状には特に制限はない。例えば、角ビレットを素材として型押しによる圧下を行った場合、断面の上下の辺の形状が幅方向（図１（ｃ）のＹ−Ｙ方向）の中央部で最大厚みとなる様な円弧形、つまり、幅中央部での厚さが最も大きくその他の部位の厚さが小さい形状であってもよい。
【００３３】
上記の対向する２つの型によって素材の軸方向に垂直な方向に素材フロント相当部に加える圧下は、曲げ打ちと同時に行ってもよい。例えば、曲げ打ちに用いる型のフロント相当部に当たる部分の形状を、前記した圧下条件を満たすような形状にして、フロント相当部の圧下と非フロント相当部の曲げ打ちを一回の型打ちで同時に行ってもよい。
【００３４】
なお、上記の素材の軸方向に垂直な方向に加える素材フロント部の圧下の前に、次のようなロール成形を行ってもよい。すなわち、レデュースロールによって素材フロント部に加えられる絞りが非フロント相当部に加えられる最大の絞り以下のものである。
【００３５】
以下、実施例により本発明を説明する．
【００３６】
【実施例】
図２に示す４気筒用のピン数４、カウンターウェイト数８の一体形クランク軸を下記の製造法１〜４の各種方法によって製造した。なお、上記クランク軸の寸法は、全長が４７７ｍｍ、フロント長さが８２ｍｍ、フロント直径が３５ｍｍ、クランクピン直径が５０ｍｍ、クランクピン長さが３０ｍｍ、クランクジャーナル直径が５４ｍｍ、クランクジャーナル長さが２６ｍｍ、カウンターウェイト高さが１１０ｍｍ、カウンターウェイト厚さが１５ｍｍである。
【００３７】
製造法１：ＪＩＳのＳ４５Ｃを素材鋼とし、断面が７６ｍｍ×７６ｍｍで種々の長さの角ビレットを通常の方法で作製した。次いで、これらの角ビレットを素材として、１２６０℃に加熱した後、素材のフランジ側の端から３８０ｍｍ以上の領域にある部分、つまりフロント相当部に、対向する２つの型により軸方向に垂直な方向に圧下を加えて４６ｍｍ厚さとした。次いで、通常の曲げ打ちを行って鍛造荒地を作製し、通常と同様に９０度軸回りに回転させた姿勢で荒打ち型上に配置し、通常の荒打ち、仕上げ打ち及びバリ抜きを行って、所定形状のクランク軸を加工した。
【００３８】
製造法２：上記の製造法１と同様の角ビレットを素材として、これらを１２６０℃に加熱した後、素材のフロント相当部を型押しによって圧下を加え、厚さ６８ｍｍにした。次いで、通常の曲げ打ちを行って鍛造荒地を作製し、通常と同様に９０度軸回りに回転させた姿勢で荒打ち型上に配置し、通常の荒打ち、仕上げ打ち及びバリ抜きを行って、所定形状のクランク軸を加工した。
【００３９】
製造法３：上記の製造法１と同様の角ビレットを素材として、これらを１２６０℃に加熱した後、素材のフロント相当部を型押しによって圧下を加え、厚さ２３ｍｍにした。次いで、通常の曲げ打ちを行って鍛造荒地を作製し、通常と同様に９０度軸回りに回転させた姿勢で荒打ち型上に配置し、通常の荒打ち、仕上げ打ち及びバリ抜きを行って、所定形状のクランク軸を加工した。
【００４０】
製造法４：ロール成形後に曲げ打ち、荒打ち及び仕上げ打ちし、更に、バリ抜きを行う従来法で一体形クランク軸を作製した。すなわち、上記の製造法１と同様の角ビレットを素材として、これらを１２６０℃に加熱した後、レデュースロールで、素材のフロント相当部に軸絞りを加え、先端部分を断面が４１ｍｍ×４１ｍｍの形状に成形した。次いで、通常の曲げ打ちを行って鍛造荒地を作製し、通常と同様に９０度軸回りに回転させた姿勢で荒打ち型上に配置し、通常の荒打ち、仕上げ打ち及びバリ抜きを行って、所定形状のクランク軸を加工した。
【００４１】
上記の各製造法でクランク軸を製造した結果は次のようになった。
【００４２】
本発明に係る製造法１によって、図２に示すクランク軸を製造する場合、素材角ビレットのフロント相当部の体積が２１８ｃｍ3 未満であると、製品フロント部に欠肉が生じた。しかし、素材角ビレットのフロント相当部の体積が２１８ｃｍ3 以上の場合には、製品フロント部に欠陥の無い良好な製品が得られた。この２１８ｃｍ3 という体積は、後述の従来法である製造法４で良好な製品を得るための素材角ビレットのフロント相当部の体積２２４ｃｍ3 よりも小さく、したがって、従来法に比べて歩留りを高くできることが明らかである。
【００４３】
製造法２によって、図２に示すクランク軸を製造する場合、素材角ビレットのフロント相当部の体積が２２９ｃｍ3 以上であれば、製品フロント部に欠陥の無い良好な製品が得られた。しかし、この場合、従来法（製造法４）で良好な製品を得るための素材角ビレットのフロント相当部の体積２２４ｃｍ3 よりも大きな体積が必要で、従来法よりも歩留りが低くなってしまう。
【００４４】
製造法３によって、図２に示すクランク軸を製造する場合、荒打ち時にフロント相当部に座屈が生じ、フロント相当部の体積に関わりなく、製品フロント部には疵が生じた。
【００４５】
従来法である製造法４によって、図２に示すクランク軸を製造する場合、素材角ビレットのフロント相当部の体積が２２４ｃｍ3 以上であれば、鍛造荒地のフロント端面に生じた凹みによる疵が製品部分から外に押し出されるため、製品フロント部に欠陥の無い良好な製品が得られた。
【００４６】
【発明の効果】
本発明の方法によれば、一体形クランク軸のフロント部に相当する部位の端面に凹みを生じさせることがないので、フロント部の歩留まりを高めることができる。
【図面の簡単な説明】
【図１】素材のビレット形状とそのフロント相当部を加工した後の形状を説明する図で、（ａ）は素材の角ビレット形状、（ｂ）はフロント相当部をロール成形した場合の形状、（ｃ）はフロント相当部を本発明に係る型押しで成形した場合の形状である。
【図２】４気筒用のピン数４、カウンターウェイト数８の一体形クランク軸を示す図で、（ａ）は側面図、（ｂ）は正面図である。[0001]
BACKGROUND OF THE INVENTION
The present invention related to the manufacturing method of the integral crankshaft is manufactured by forging, particularly, reduction of the material front corresponding portion by embossing of the two types of opposing, clinched, rough beating, finishing beating and The present invention relates to a method of manufacturing an integrated crankshaft that goes through each process of deburring.
[0002]
[Prior art]
Conventionally, a crankshaft of an automobile or the like has been manufactured by casting or forging. However, in recent years, as the engine has become lighter and the output has been increased, the crankshaft is required to have high strength and high toughness, and the demand for an integrated crankshaft manufactured by forging is increasing.
[0003]
The integrated crankshaft manufactured by forging (hereinafter also referred to as “product”) is made of carbon steel or alloy steel square billets or round billets, for example, (1) roll forming, (2) bending. Formed through the steps of punching (bending), (3) roughing (first step of die forging), (4) finishing punching (second step of die forging), and (5) deburring (deburring). I came. In general, a material to be forged formed through roll forming and bending is subjected to roughing in a posture rotated 90 degrees around an axis with respect to the posture at the time of bending.
[0004]
Of the above-mentioned steps (1) to (5), the roll forming of (1) is a rolling forming step using a roll having irregularities, and by adjusting the cross-sectional area of each part of the material (material to be forged), This is a process of performing volume allocation in the direction. That is, in this roll forming, a portion corresponding to the product front portion of the material is stretched into an elongated shape having a cross-sectional area close to the front portion of the product so as to increase the yield in the vicinity of the front portion.
[0005]
However, when rolling with a roll, the surface of the workpiece tends to extend from the inside. For this reason, the end surface of the part corresponding to the product front part after being molded with a roll often has a concave shape at the center as shown in FIG. 1B described later, and this is shown in (3). When subjected to rough hammering, the end face is folded inside to generate wrinkles. If such wrinkles occur in the product part, it becomes a defective product. Therefore, in the past, the part corresponding to the product front part of the forged material before roughing was processed in advance to ensure the “disposal allowance”, and the above-mentioned wrinkles entered the “disposal allowance”. It was adjusted so as not to remain. For this reason, when processing a forging material by roll forming, it was inevitable that the yield of a front part became low.
[0006]
Japanese Laid-Open Patent Publication No. 2-255240 discloses a “die forging crankshaft roughing method” that can improve the yield during roll forming by bringing the cross-sectional area distribution of the roll wasteland closer to the cross-sectional area distribution of the product crankshaft. ing. However, since the technique proposed in this publication is also roll forming, it is completely unavoidable that the end surface of the portion corresponding to the product front portion described above has a dent, and therefore the product In order to prevent wrinkles from entering the part, a discarding fee was required, and the yield at the front part was still low.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described situation, and an object of the present invention is to provide an integrated crank that can increase the yield of the front portion without causing a dent in the end surface of the portion corresponding to the front portion of the integrated crankshaft. It is to provide a method for manufacturing a shaft . In the following description, the integral crankshaft is also simply referred to as “crankshaft”.
[0008]
[Means for Solving the Problems]
Gist of the present invention is a method of manufacturing integral crankshaft shown in the following (1) and (2).
[0009]
That is,
“ (1) A manufacturing method of an integrated crankshaft that includes the steps of pressing the material front by pressing with two opposing molds , bending punching, roughing, finishing punching, and deburring. two embossed in producing the integrated type crankshaft forging wasteland by the pressure of the material front portion corresponding by a mold, the front portion corresponding material, thickness in a direction perpendicular to the axial direction of the material the material thickness of The method of manufacturing an integrated crankshaft is characterized in that it is reduced to 80 to 35% .
“(2) A method for manufacturing an integrated crankshaft according to (1) above, wherein when the forged crankshaft forged waste is manufactured, the material front equivalent portion is reduced by pressing the two opposed dies. A method of manufacturing an integrated crankshaft characterized in that it is bent at the same time. "
[0010]
The “forged wasteland” refers to a material to be forged that is subjected to roughing, which is the first step of die forging. Also, the already mentioned "the front section of the integral crankshaft" refers to one axial end of the crank shaft, the cross-sectional in the shape perpendicular to the axis relative to other sites cylindrical section The area is small.
The “front equivalent part” of the material refers to the part of the material that becomes the front part of the product crankshaft. A portion other than the “front equivalent portion” of the material is referred to as a “non-front equivalent portion”.
[0011]
The “axial direction” of the material refers to the XX direction in FIG. 1A, that is, the length direction of the material, and “thickness” refers to the maximum dimension in the reduction direction in the cross section perpendicular to the axial direction. Say.
[0012]
In order to solve the above-mentioned problems, the present inventors conducted a basic experiment on an 8-counter weight crankshaft having a shape of four cylinders and having four pins as shown in FIG.
[0013]
That is, first, roll forming, bending punching, rough punching, and finishing punching were performed by a conventional method using a conventional size JIS S45C square billet.
[0014]
FIG. 1A shows the shape of a square billet that is a material. As shown in FIG. 1B, the shape after roll forming the square billet is a portion having the same cross section as the square billet of the material (hereinafter referred to as “thick body”), the front portion of the product crankshaft. It consisted of a corresponding part (hereinafter referred to as “thin body part”) and a taper part connecting the thick body part and the thin body part. Note that the end face of the “thin body” had a concave shape at the center. The front portion of the crankshaft after bending and roughing was applied to this, and finally finishing was made, mainly composed of the material of the “narrow body” and the taper after the roll forming.
[0016]
Using the above-mentioned conventional size JIS S45C square billet as a raw material, the front part of products that have been roll-formed, bent, roughed and finished by the usual methods will have wrinkles and unfilled parts called undercuts. There wasn't.
[0017]
Next, the cross-sectional shape is the same as the above-mentioned square billet of the conventional size, but roll forming, bending punching, rough punching and finishing punching are carried out in the usual manner using materials with various lengths of the front equivalent part changed. Went. Also in this case, the end face of the “thin body” had a concave shape at the center. Based on experiments in which the length of the front equivalent part is changed in various ways, the volume of the front equivalent part of the billet as the material is less than a specific value for each cross-sectional shape (hereinafter, this specific value is referred to as VR). It was found that wrinkles due to the folding of the central concave end surface generated by roll forming occurred in the front part of the product after finish punching.
[0018]
Furthermore, the cross-sectional shape is the same as that of the conventional size square billet, and the material corresponding to the length of the front equivalent part is changed variously. Instead of roll forming, the front equivalent part is perpendicular to the axial direction of the material. In addition, an experiment was performed in which a reduction by embossing was applied so that the thickness was 60% of the material thickness, and then a normal bending punching was performed on the non-front equivalent portion, followed by a rough punching and finish punching by a normal method. In this case, as shown in FIG. 1 (c), since the central recess did not occur on the end face of the “narrow body”, the center as seen when roll forming was performed on the product front part after finishing. No wrinkles were generated due to the folding of the recessed end face. However, it was found that when the volume of the front equivalent part of the billet as the material is less than a specific value (hereinafter, this specific value is referred to as VN), the product front part is thin.
[0019]
When “VR” was compared with “VN” in the case where the above-described front equivalent portion was pressed by pressing so that the thickness was 60% of the material thickness, VR> VN. From this, it has also been found that the yield of the front portion can be increased by embossing under the above conditions as compared with the case of roll forming.
[0020]
Therefore, the cross-sectional shape is the same as the square billet of the conventional size, and the material equivalent to the front is used in the direction perpendicular to the axial direction of the material, instead of roll forming, with the material corresponding to the length of the front equivalent being changed variously. The part is subjected to pressing by embossing so that the thickness becomes various proportions of the material thickness, and then a normal bending punching is performed on the non-front equivalent part, and then a roughing and finishing punching is performed by a normal method. It was. From this experiment, the following matters became clear.
[0021]
(A) When the front equivalent part is pressed by pressing in the direction perpendicular to the axial direction of the material (hereinafter simply referred to as “pressing by pressing the material front equivalent part”), the thickness of the front equivalent part after the reduction is the material If the thickness is 80 to 35% of the thickness, the minimum volume VN of the front equivalent part required for the front part of the product is not equal to or less than the VR because no thinning occurs in the product front part.
[0022]
(B) If the thickness of the front equivalent part after reduction is over 80% of the material thickness when the material equivalent to the front part is pressed, the front equivalent part is the minimum necessary for the product front part to be thin. On the contrary, the volume VN becomes larger than the VR.
[0023]
(C) If the thickness of the front equivalent part after reduction is less than 35% of the material thickness when the material front equivalent part is pressed, the front equivalent part will buckle during rough hitting, so the product front A wrinkle occurs in the part.
[0024]
In addition, the above-mentioned buckling has a flatness after the reduction of the material front equivalent part is too large, and after bending, when it is rotated 90 degrees around the axis and placed on the rough die, it corresponds to the front equivalent part. This is based on the fact that the height of is too large compared to the width.
[0025]
From the above (a) to (c), normal pressing is applied to the front equivalent part of the material so that the thickness is 80 to 35% of the material thickness in the direction perpendicular to the axial direction of the material. It has been found that the yield of the front part can be made higher than in the case of roll forming.
[0026]
The present invention has been completed based on the above findings.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
[0028]
First, a material billet is manufactured by a normal method from a steel ingot melted by a normal method. In addition, the cross-sectional size of the material billet is the cross-section of the non-front equivalent part of the steel material after performing axial drawing with a reduce roll when performing normal roll forming, i.e., adding axial drawing with a reduce roll. It should just be the same thing.
[0029]
Next, the material corresponding to the front portion of the material is molded by applying pressure reduction so that the thickness becomes 80 to 35% of the material thickness in a direction perpendicular to the axial direction of the material by two opposing molds. Thereafter, bending, roughing, and finishing are performed by a normal method, and deburring is further performed. Note that the material front equivalent portion may be reduced and bent by two opposing molds at the same time.
[0030]
According to the above method, the yield of the front portion can be increased as compared to the case of a normal manufacturing method in which bending punching, rough punching, and finish punching are performed after roll forming and further deburring is performed.
[0031]
In addition, when the thickness after the reduction exceeds 80% of the material thickness, the minimum volume corresponding to the front portion necessary to prevent the product front portion from being thinned does not cause wrinkles in the conventional roll forming. Therefore, the yield is not increased because it is larger than the volume of the front equivalent part required at the minimum. On the other hand, when the thickness after the reduction is less than 35% of the material thickness, buckling occurs in the front equivalent part, and thus wrinkles occur in the product front part.
[0032]
As long as the thickness after reduction is 80 to 35% of the material thickness, there is no particular limitation on the cross-sectional shape after the reduction is applied in the direction perpendicular to the axial direction of the material. For example, when a square billet is used as the raw material and the pressing is performed by embossing, an arc in which the shape of the upper and lower sides of the cross section is the maximum thickness at the center in the width direction (Y-Y direction in FIG. 1C) shape, i.e., may be a shape has small thickness of the largest other sites thickness in the width center portion.
[0033]
The reduction applied to the material front corresponding portion in the direction perpendicular to the material axial direction by the two opposed molds may be performed simultaneously with the bending. For example, the shape of the part corresponding to the front equivalent part of the die used for bending punching is shaped so as to satisfy the above-mentioned reduction condition, and the pressing of the front equivalent part and the bending punching of the non-front equivalent part are simultaneously performed by one punching. You may go.
[0034]
In addition, you may perform the following roll forming before the rolling of the raw material front part added to the direction perpendicular | vertical to the axial direction of said raw material. That is, the aperture applied to the material front portion by the reduce roll is less than the maximum aperture applied to the non-front equivalent portion.
[0035]
Hereinafter, the present invention will be described by way of examples.
[0036]
【Example】
An integrated crankshaft with 4 pins and 8 counterweights for 4 cylinders shown in FIG. 2 was manufactured by various methods 1 to 4 described below. The dimensions of the crankshaft are as follows: total length is 477 mm, front length is 82 mm, front diameter is 35 mm, crankpin diameter is 50 mm, crankpin length is 30 mm, crank journal diameter is 54 mm, crank journal length is 26 mm, The counterweight height is 110 mm and the counterweight thickness is 15 mm.
[0037]
Production Method 1: JIS S45C was used as a raw material steel, and square billets having a cross section of 76 mm × 76 mm and various lengths were produced by a usual method. Next, after heating these square billets to 1260 ° C using the square billet as a raw material, a direction perpendicular to the axial direction by two opposing molds in a portion in the region of 380 mm or more from the flange end of the raw material, that is, the front equivalent portion The thickness was reduced to 46 mm. Next, normal forging was performed to produce the forged rough ground, and it was placed on the roughing die in a posture rotated around the axis by 90 degrees as usual, and normal roughing, finishing punching and deburring were performed. A crankshaft with a predetermined shape was machined.
[0038]
Production method 2: Using the same billet as in production method 1 described above as a raw material, these were heated to 1260 ° C., and then the front equivalent part of the raw material was reduced by embossing to a thickness of 68 mm. Next, normal forging was performed to produce the forged rough ground, and it was placed on the roughing die in a posture rotated around the axis by 90 degrees as usual, and normal roughing, finishing punching and deburring were performed. A crankshaft with a predetermined shape was machined.
[0039]
Manufacturing method 3: Using the same billet as in manufacturing method 1 above as a raw material, these were heated to 1260 ° C., and then the front equivalent part of the raw material was reduced by embossing to a thickness of 23 mm. Next, normal forging was performed to produce the forged rough ground, and it was placed on the roughing die in a posture rotated around the axis by 90 degrees as usual, and normal roughing, finishing punching and deburring were performed. A crankshaft with a predetermined shape was machined.
[0040]
Production method 4: An integrated crankshaft was manufactured by a conventional method in which bending, roughing, and finishing were performed after roll forming, and further deburring was performed. That is, using the same billet as in manufacturing method 1 above, heating them to 1260 ° C., then using a reduce roll, adding an axial restriction to the front equivalent part of the material, and forming a tip with a cross section of 41 mm × 41 mm Molded into. Next, normal forging was performed to produce the forged rough ground, and it was placed on the roughing die in a posture rotated around the axis by 90 degrees as usual, and normal roughing, finishing punching and deburring were performed. A crankshaft with a predetermined shape was machined.
[0041]
The result of manufacturing the crankshaft by each of the manufacturing methods described above was as follows.
[0042]
When the crankshaft shown in FIG. 2 is manufactured by the manufacturing method 1 according to the present invention, if the volume of the front equivalent part of the material square billet is less than 218 cm 3 , the product front part is thinned. However, when the volume of the front equivalent part of the material square billet was 218 cm 3 or more, a good product free from defects in the product front part was obtained. The volume of this 218Cm 3 is smaller than the volume 224cm 3 of a front portion corresponding material angle billet for good product in Process 4 is a conventional method described later, therefore, be possible to increase the yield in comparison with the conventional method Is clear.
[0043]
When the crankshaft shown in FIG. 2 is manufactured by the manufacturing method 2, if the volume of the front equivalent part of the material square billet is 229 cm 3 or more, a good product having no defects in the product front part is obtained. However, in this case, a volume larger than the volume 224 cm 3 of the front equivalent part of the material square billet for obtaining a good product by the conventional method (manufacturing method 4) is required, and the yield is lower than the conventional method.
[0044]
When the crankshaft shown in FIG. 2 was manufactured by the manufacturing method 3, buckling occurred in the front equivalent part during rough hitting, and wrinkles occurred in the product front part regardless of the volume of the front equivalent part.
[0045]
When the crankshaft shown in FIG. 2 is manufactured by the manufacturing method 4 which is a conventional method, if the volume of the front equivalent part of the material square billet is 224 cm 3 or more, the wrinkles due to the dents formed on the front end surface of the forged wasteland will be Since it was pushed out from the part, a good product with no defects in the product front part was obtained.
[0046]
【The invention's effect】
According to the method of the present invention, the end surface of the portion corresponding to the front portion of the integrated crankshaft is not recessed, so that the yield of the front portion can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a billet shape of a material and a shape after processing a front equivalent part thereof, (a) is a square billet shape of the material, (b) is a shape when a front equivalent part is roll-formed, (C) is a shape at the time of shape | molding the front equivalent part by the stamping which concerns on this invention.
FIGS. 2A and 2B are diagrams showing an integrated crankshaft having four pins and four counterweights for a four-cylinder, in which FIG. 2A is a side view and FIG. 2B is a front view;
Claims (2)
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|---|---|---|---|
| JP22008599A JP3680651B2 (en) | 1999-08-03 | 1999-08-03 | Manufacturing method of integral crankshaft |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22008599A JP3680651B2 (en) | 1999-08-03 | 1999-08-03 | Manufacturing method of integral crankshaft |
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| Publication Number | Publication Date |
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| JP2001047177A JP2001047177A (en) | 2001-02-20 |
| JP3680651B2 true JP3680651B2 (en) | 2005-08-10 |
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