JP2009052125A

JP2009052125A - Ring gear and method for manufacturing ring gear

Info

Publication number: JP2009052125A
Application number: JP2007222740A
Authority: JP
Inventors: Hideyuki Sakagami; 秀幸坂上
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2007-08-29
Filing date: 2007-08-29
Publication date: 2009-03-12

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ring gear and a method for manufacturing this gear, wherein the heat-treating deformation can be restrained at the time of rapidly cooling after carburize-treatment in the manufacturing process. <P>SOLUTION: Since an annular step-difference 9 is formed at the corner part between the fitting surface 2 and the outer circumferential surface 8 of the ring gear 1, the fitting surface side edge part 10 is formed between the step-difference 9 and the fitting surface 2 and also, the outer circumferential surface side edge part 11 is formed between the annular step-difference 9 and the outer circumferential surface 8. In this way, the difference of cooling speed at the rapid cooling time after the carburize-treatment, is relaxed, and the timing of the shrinkage and the expansion of the fitting surface 2 can be adjusted to the timing of the outer-end part side edge part 5 and the inner-end part side edge part 7 and thus, the heat-treating deformation at the rapid cooling time, can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、リングギヤ及びリングギヤの製造方法に関するもので、特に、製造過程において浸炭処理後に急冷されるリングギヤ及びその製造方法に関する。 The present invention relates to a ring gear and a method for manufacturing the ring gear, and more particularly to a ring gear that is rapidly cooled after carburizing in the manufacturing process and a method for manufacturing the ring gear.

一般に、ハイポイド歯車対を構成するリングギヤは、機械加工（ハイポイド歯切り加工）された後、浸炭される。そして、リングギヤは、浸炭直後の高温度（例えば、950℃）のオーステナイト状態から急冷されることで、炭素濃度が高められた表面部はマルテンサイト化されて硬化され、炭素濃度が低い状態の内部は硬化しないでねばり強さが確保される。しかしながら、リングギヤは、浸炭処理後に急冷されると、取付面の内側部分が浮き上がる形態の熱処理変形を生じる。この熱処理変形を生じたリングギヤをディファレンシャルに組付けた場合、リングギヤとピニオンとの歯当たりが移動して、ディファレンシャルから振動や騒音が発生する原因になる。そこで、本出願人は、リングギヤの取付面を防炭処理することで取付面をマルテンサイト化させて硬化させた後、このリングギヤの取付面以外の部分をマルテンサイト化させて体積を膨張させるリングギヤの熱処理方法を開発した（特許文献１参照）。このようにリングギヤを熱処理することで、取付面への体積膨張の影響を低減させて取付面の熱処理変形を抑制することができる。 Generally, ring gears constituting a hypoid gear pair are carburized after being machined (hypoid gear cutting). The ring gear is rapidly cooled from an austenite state at a high temperature (for example, 950 ° C.) immediately after carburizing, so that the surface portion with increased carbon concentration is martensitized and hardened, and the inside of the state in which the carbon concentration is low. The stickiness is ensured without curing. However, when the ring gear is rapidly cooled after the carburizing process, the ring gear undergoes a heat treatment deformation in which the inner portion of the mounting surface is lifted. When the ring gear that has undergone this heat treatment deformation is assembled to the differential, the tooth contact between the ring gear and the pinion moves, causing vibration and noise from the differential. Therefore, the present applicant has made the ring gear mounting surface martensite by hardening the mounting surface, and then hardening the portion other than the ring gear mounting surface to martensite to expand the volume. Has been developed (see Patent Document 1). By heat-treating the ring gear in this way, it is possible to reduce the influence of volume expansion on the mounting surface and suppress heat treatment deformation of the mounting surface.

しかしながら、上記熱処理方法においては、取付面に防炭剤の塗布ムラがあると、浸炭の度合いにばらつきが生じて熱処理変形抑制効果を十分に発揮することができない。また、上記熱処理方法では、防炭剤塗布工程と防炭剤洗浄工程とを新規に設ける必要があることから生産性が低下する。さらに、取付面のボルト穴に防炭剤が残留してボルトの締付け不良を生じる虞がある。ところで、本出願人は、リングギヤにおける熱処理変形発生のメカニズムを追究した結果、リングギヤの熱処理変形の主原因は、リングギヤが浸炭（浸炭焼入れ）時に高温度に加熱された状態から急冷された時の当該リングギヤ全体における冷却速度の差であることを究明した。以下、図２に示されるように、鍛造、及び機械加工（ハイポイド歯切り加工）によって得られたリングギヤを950℃に加熱して浸炭（浸炭焼入れ）した後、当該リングギヤを急冷（油冷）した場合の熱処理変形発生のメカニズムを図９を用いて説明する。 However, in the above heat treatment method, if there is uneven application of the carburizing agent on the mounting surface, the degree of carburization varies and the heat treatment deformation suppressing effect cannot be sufficiently exhibited. Moreover, in the said heat processing method, since it is necessary to newly provide a carburizing agent application | coating process and a carburizing agent washing | cleaning process, productivity falls. Furthermore, there is a possibility that the anti-carburizing agent remains in the bolt holes on the mounting surface, resulting in poor bolt tightening. By the way, as a result of pursuing the mechanism of heat treatment deformation generation in the ring gear, the present applicant has found that the main cause of the heat treatment deformation of the ring gear is that when the ring gear is rapidly cooled from a state of being heated to a high temperature during carburizing (carburizing and quenching). It was investigated that the cooling rate was different in the entire ring gear. Hereinafter, as shown in FIG. 2, the ring gear obtained by forging and machining (hypoid gear cutting) was heated to 950 ° C. and carburized (carburized and quenched), and then the ring gear was rapidly cooled (oil-cooled). The mechanism of heat treatment deformation in this case will be described with reference to FIG.

まず、全体が均一に加熱された高温度状態（950℃）のリングギヤ２１が急冷されると、歯先面３と外端部端面４との稜部５（以下、外端部側稜部５という）及び歯先面３と内端部端面６との稜部７（以下、内端部側稜部７という）の冷却速度が他の部分の冷却速度と比較して速いことに起因して、図９（Ａ）に示されるように、外端部側稜部５及び内端部側稜部７は他の部分よりも先に収縮を開始する。これにより、リングギヤ２１は、取付面２の外側部分（図９（Ａ）における右側部分）が浮き上がるように変形する。そして、冷却開始から所定時間が経過すると、図９（Ｂ）に示されるように、外端部側稜部５及び内端部側稜部７がオーステナイト状態からマルテンサイト化（以下、組織変態という）して膨張すると共に、他の部分が収縮する。これににより、リングギヤ２１は、取付面２の内側部分（図９（Ｂ）における左側部分）が浮き上がるように変形する。次に、図９（Ｃ）に示されるように、リングギヤ２１は、外端部側稜部５と内端部側稜部７とを除く他の部分が組織変態して膨張し、最終的に、取付面２の内側部分が浮き上がることになる。
特開昭６３−１６３０６９ First, when the ring gear 21 in a high temperature state (950 ° C.), which is uniformly heated as a whole, is rapidly cooled, a ridge portion 5 between the tooth tip surface 3 and the outer end portion end surface 4 (hereinafter, the outer end side ridge portion 5). And the cooling rate of the ridge portion 7 between the tooth tip surface 3 and the inner end portion end surface 6 (hereinafter referred to as the inner end side ridge portion 7) is higher than the cooling rate of other portions. As shown in FIG. 9A, the outer end side ridge portion 5 and the inner end side ridge portion 7 start to contract before other portions. Thereby, the ring gear 21 is deformed so that the outer portion of the mounting surface 2 (the right portion in FIG. 9A) is lifted. And when predetermined time passes since cooling start, as FIG.9 (B) shows, the outer edge part ridge part 5 and the inner edge part ridge part 7 will be martensite from an austenite state (henceforth structure transformation). ) And expand, and other parts contract. Thereby, the ring gear 21 is deformed so that the inner part of the mounting surface 2 (the left part in FIG. 9B) is lifted. Next, as shown in FIG. 9 (C), the ring gear 21 expands with the other portions except the outer end side ridge portion 5 and the inner end side ridge portion 7 transformed and finally expanded. The inner part of the mounting surface 2 is lifted.
JP 63-163069 A

そこで本発明は、上記事情に鑑みてなされたもので、製造過程において浸炭処理後に急冷される時の熱処理変形を抑制することが可能なリングギヤ及びその製造方法を提供することを課題としてなされたものである。 Then, this invention was made in view of the said situation, and it was made as a subject to provide the ring gear which can suppress the heat processing deformation | transformation at the time of quenching after a carburizing process in a manufacture process, and its manufacturing method. It is.

上記課題を解決するために、本発明のリングギヤは、製造過程において浸炭処理後に急冷されるリングギヤであって、取付面と外周面との角部に環状の段差が形成されることを特徴とする。 In order to solve the above-mentioned problems, the ring gear of the present invention is a ring gear that is rapidly cooled after carburizing in the manufacturing process, and is characterized in that an annular step is formed at the corner between the mounting surface and the outer peripheral surface. .

上記課題を解決するために、本発明のリングギヤの製造方法は、リングギヤの取付面と外周面との角部に、外端歯先円直径Dに基き半径方向の寸法Lr及び高さ方向の寸法Lhが設定される環状の段差を加工して、この環状の段差が加工されたリングギヤを浸炭処理後に急冷することを特徴とする。 In order to solve the above-described problem, the ring gear manufacturing method of the present invention includes a radial dimension Lr and a height dimension based on the outer end tip diameter D at the corners of the ring gear mounting surface and the outer peripheral surface. An annular step where Lh is set is processed, and the ring gear in which the annular step is processed is rapidly cooled after carburizing.

（発明の態様）
以下に、本願において特許請求が可能と認識されている発明（以下、請求可能発明と称する）の態様を例示し、例示された各態様について説明する。ここでは、各態様を、特許請求の範囲と同様に、項に区分すると共に各項に番号を付し、必要に応じて他の項の記載を引用する形式で記載する。これは、請求可能発明の理解を容易にするためであり、請求可能発明を構成する構成要素の組み合わせを、以下の各項に記載されたものに限定する趣旨ではない。つまり、請求可能発明は、各項に付随する記載、実施形態の記載等を参酌して解釈されるべきであり、その解釈に従う限りにおいて、各項の態様にさらに他の構成要素を付加した態様も、また、各項の態様から構成要素を削除した態様も、請求可能発明の一態様となり得る。
なお、以下の各項において、（１）〜（６）項の各々が、請求項１〜６の各々に相当する。 (Aspect of the Invention)
In the following, aspects of the invention that is recognized as being capable of being claimed in the present application (hereinafter referred to as claimable invention) will be exemplified, and each exemplified aspect will be described. Here, as in the claims, each aspect is divided into paragraphs, numbers are assigned to the respective paragraphs, and the descriptions of other paragraphs are cited as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combination of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiment, etc., and as long as the interpretation is followed, another aspect is added to the aspect of each section. Moreover, the aspect which deleted the component from the aspect of each term can also be one aspect of the claimable invention.
In the following items, each of items (1) to (6) corresponds to each of claims 1 to 6.

（１）製造過程において浸炭処理後に急冷されるリングギヤであって、取付面と外周面との角部に環状の段差が形成されることを特徴とするリングギヤ。
本項に記載のリングギヤによれば、取付面と外周面との角部に環状の段差を形成して、環状の段差と取付面との間、及び環状の段差と外周面との間に、急冷時における冷却速度が速い稜部（エッジ）をそれぞれ形成したので、リングギヤの急冷時における冷却速度の差が緩和されて、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、段差壁面と取付面との稜部の角度、及び段差壁面と外周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と外周面とがなす角度は、稜部の冷却速度を高めるために直角、より好ましくは、鋭角であることが望ましい。
本項の態様において、段差壁面は平面で構成されていても曲面で構成されていてもよい。本項の態様における必要条件は、段差壁面と取付面との稜部の角度、及び段差壁面と外周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と外周面とがなす角度が、直角、あるいは鋭角であることである。 (1) A ring gear that is rapidly cooled after a carburizing process in the manufacturing process, wherein an annular step is formed at a corner between the mounting surface and the outer peripheral surface.
According to the ring gear described in this section, an annular step is formed at the corner between the mounting surface and the outer peripheral surface, and between the annular step and the mounting surface, and between the annular step and the outer peripheral surface, Since the ridges (edges) having a high cooling rate during the rapid cooling are formed, the difference in the cooling rate during the rapid cooling of the ring gear is alleviated, and the heat treatment deformation of the ring gear during the rapid cooling can be prevented.
In the aspect of this section, the angle of the ridge between the step wall surface and the mounting surface, and the angle of the ridge between the step wall surface and the outer peripheral surface, that is, the angle formed by the step wall surface and the mounting surface, and the step wall surface and the outer peripheral surface In order to increase the cooling rate of the ridge, it is desirable that the angle formed by is a right angle, more preferably an acute angle.
In the aspect of this section, the stepped wall surface may be a flat surface or a curved surface. The necessary conditions in the aspect of this section are the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the outer peripheral surface, that is, the angle formed by the step wall and the mounting surface, and the step wall. The angle formed by the outer peripheral surface is a right angle or an acute angle.

（２）製造過程において浸炭処理後に急冷されるリングギヤであって、取付面と軸孔内周面との角部に環状の段差が設けられることを特徴とするリングギヤ。
本項に記載のリングギヤによれば、取付面と軸孔内周面との角部に環状の段差を形成して、環状の段差と取付面との間、及び環状の段差と軸孔内周面との間に、急冷時における冷却速度が速い稜部（エッジ）をそれぞれ形成したので、リングギヤの急冷時における冷却速度の差が緩和されて、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、段差壁面と取付面との稜部の角度、及び段差壁面と軸孔内周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と軸孔内周面とがなす角度は、稜部の冷却速度を高めるために直角、より好ましくは、鋭角であることが望ましい。
本項の態様において、段差壁面は平面で構成されていても曲面で構成されていてもよい。本項の態様における必要条件は、段差壁面と取付面との稜部の角度、及び段差壁面と軸孔内周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と軸孔内周面とがなす角度が、直角、あるいは鋭角であることである。 (2) A ring gear that is rapidly cooled after a carburizing process in the manufacturing process, wherein an annular step is provided at a corner between the mounting surface and the inner peripheral surface of the shaft hole.
According to the ring gear described in this section, an annular step is formed at the corner between the mounting surface and the inner peripheral surface of the shaft hole, and between the annular step and the mounting surface, and between the annular step and the inner periphery of the shaft hole. Since ridges (edges) having a high cooling rate during quenching are formed between the surface and the surface, the difference in the cooling rate during quenching of the ring gear is alleviated, and heat treatment deformation of the ring gear during quenching can be prevented. .
In the aspect of this paragraph, the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the inner peripheral surface of the shaft hole, that is, the angle formed by the step wall and the mounting surface, and the step wall The angle formed by the inner peripheral surface of the shaft hole is preferably a right angle, more preferably an acute angle, in order to increase the cooling rate of the ridge.
In the aspect of this section, the stepped wall surface may be a flat surface or a curved surface. The necessary conditions in this aspect are the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the inner peripheral surface of the shaft hole, that is, the angle formed by the step wall and the mounting surface, and The angle formed by the step wall surface and the inner peripheral surface of the shaft hole is a right angle or an acute angle.

（３）環状の段差は、半径方向の寸法Lr及び高さ方向の寸法Lhが、外端歯先円直径Dの２〜４％である（１）又は（２）に記載のリングギヤ。
本項に記載のリングギヤによれば、リングギヤの強度を確保しつつ、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、半径方向の寸法Lrと高さ方向の寸法Lhとは、外端歯先円直径Dの２〜４％であれば必ずしも同一寸法（Lr＝Lh）でなくてもよい。 (3) The annular step is the ring gear according to (1) or (2), wherein the radial dimension Lr and the height dimension Lh are 2 to 4% of the outer end tip diameter D.
According to the ring gear described in this section, it is possible to prevent heat treatment deformation of the ring gear during rapid cooling while ensuring the strength of the ring gear.
In the aspect of this section, the dimension Lr in the radial direction and the dimension Lh in the height direction do not necessarily have to be the same dimension (Lr = Lh) as long as it is 2 to 4% of the outer end tip circle diameter D.

（４）リングギヤの取付面と外周面との角部に、外端歯先円直径Dに基き半径方向の寸法Lr及び高さ方向の寸法Lhが決まる環状の段差を加工して、この環状の段差が加工されたリングギヤを浸炭処理後に急冷することを特徴とするリングギヤの製造方法。
本項に記載のリングギヤの製造方法によれば、取付面と外周面との角部に、外端歯先円直径Dに基き半径方向の寸法Lr及び高さ方向の寸法Lhが決まる環状の段差を加工して、環状の段差と取付面との間、及び環状の段差と外周面との間に、急冷時における冷却速度が速い稜部（エッジ）をそれぞれ形成したので、リングギヤの急冷時における冷却速度の差が緩和されて、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、段差壁面と取付面との稜部の角度、及び段差壁面と外周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と外周面とがなす角度は、稜部の冷却速度を高めるために直角、より好ましくは、鋭角であることが望ましい。
本項の態様において、段差壁面は平面で構成されていても曲面で構成されていてもよい。本項の態様における必要条件は、段差壁面と取付面との稜部の角度、及び段差壁面と外周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と外周面とがなす角度が、直角、あるいは鋭角であることである。 (4) At the corner between the ring gear mounting surface and the outer peripheral surface, an annular step having a radial dimension Lr and a height dimension Lh determined on the basis of the outer end tip diameter D is processed. A ring gear manufacturing method, comprising: quenching a ring gear with a step processed after carburizing treatment.
According to the manufacturing method of the ring gear described in this section, the annular step in which the radial dimension Lr and the height dimension Lh are determined based on the outer end tip diameter D on the corners of the mounting surface and the outer peripheral surface. Since the ridges (edges) having a high cooling rate during quenching were formed between the annular step and the mounting surface, and between the annular step and the outer peripheral surface, respectively, when the ring gear was rapidly cooled The difference in cooling rate is alleviated, and the heat treatment deformation of the ring gear during rapid cooling can be prevented.
In the aspect of this section, the angle of the ridge between the step wall surface and the mounting surface, and the angle of the ridge between the step wall surface and the outer peripheral surface, that is, the angle formed by the step wall surface and the mounting surface, and the step wall surface and the outer peripheral surface In order to increase the cooling rate of the ridge, it is desirable that the angle formed by is a right angle, more preferably an acute angle.
In the aspect of this section, the stepped wall surface may be a flat surface or a curved surface. The necessary conditions in the aspect of this section are the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the outer peripheral surface, that is, the angle formed by the step wall and the mounting surface, and the step wall. The angle formed by the outer peripheral surface is a right angle or an acute angle.

（５）リングギヤの取付面と軸孔内周面との角部に、外端歯先円直径Dに基き半径方向の寸法Lr及び高さ方向の寸法Lhが決まる環状の段差を加工して、この環状の段差が加工されたリングギヤを浸炭処理後に急冷することを特徴とするリングギヤの製造方法。
本項に記載のリングギヤの製造方法によれば、取付面と軸孔内周面との角部に、外端歯先円直径Dに基き半径方向の寸法Lr及び高さ方向の寸法Lhが決まる環状の段差を加工して、環状の段差と取付面との間、及び環状の段差と軸孔内周面との間に、急冷時における冷却速度が速い稜部（エッジ）をそれぞれ形成したので、リングギヤの急冷時における冷却速度の差が緩和されて、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、段差壁面と取付面との稜部の角度、及び段差壁面と軸孔内周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と軸孔内周面とがなす角度は、稜部の冷却速度を高めるために直角、より好ましくは、鋭角であることが望ましい。
本項の態様において、段差壁面は平面で構成されていても曲面で構成されていてもよい。本項の態様における必要条件は、段差壁面と取付面との稜部の角度、及び段差壁面と軸孔内周面との稜部の角度、すなわち、段差壁面と取付面とがなす角度、及び段差壁面と軸孔内周面とがなす角度が、直角、あるいは鋭角であることである。 (5) At the corner between the ring gear mounting surface and the inner peripheral surface of the shaft hole, an annular step is determined in which the radial dimension Lr and the height dimension Lh are determined based on the outer end tip diameter D. A ring gear manufacturing method, characterized in that the ring gear in which the annular step is processed is rapidly cooled after carburizing.
According to the manufacturing method of the ring gear described in this section, the radial dimension Lr and the height dimension Lh are determined at the corners of the mounting surface and the inner peripheral surface of the shaft hole based on the outer end tooth tip diameter D. Since the annular step was processed, ridges (edges) with a high cooling rate during quenching were formed between the annular step and the mounting surface and between the annular step and the inner peripheral surface of the shaft hole. The difference in the cooling rate during the rapid cooling of the ring gear is alleviated, and the heat treatment deformation of the ring gear during the rapid cooling can be prevented.
In the aspect of this paragraph, the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the inner peripheral surface of the shaft hole, that is, the angle formed by the step wall and the mounting surface, and the step wall The angle formed by the inner peripheral surface of the shaft hole is preferably a right angle, more preferably an acute angle, in order to increase the cooling rate of the ridge.
In the aspect of this section, the stepped wall surface may be a flat surface or a curved surface. The necessary conditions in this aspect are the angle of the ridge between the step wall and the mounting surface, and the angle of the ridge between the step wall and the inner peripheral surface of the shaft hole, that is, the angle formed by the step wall and the mounting surface, and The angle formed by the step wall surface and the inner peripheral surface of the shaft hole is a right angle or an acute angle.

（６）リングギヤに、半径方向の寸法Lr及び高さ方向の寸法Lhが外端歯先円直径Dの２〜４％である環状の段差を加工して、このリングギヤを浸炭処理後に急冷する（４）又は（５）のリングギヤの製造方法。
本項に記載のリングギヤの製造方法によれば、リングギヤの強度を確保しつつ、急冷時におけるリングギヤの熱処理変形を防ぐことができる。
本項の態様において、半径方向の寸法Lrと高さ方向の寸法Lhとは、外端歯先円直径Dの２〜４％であれば必ずしも同一寸法（Lr＝Lh）でなくてもよい。 (6) An annular step having a radial dimension Lr and a height dimension Lh of 2 to 4% of the outer end tip diameter D is processed in the ring gear, and the ring gear is quenched after carburizing ( A method for producing a ring gear according to 4) or (5).
According to the method for manufacturing a ring gear described in this section, it is possible to prevent heat treatment deformation of the ring gear during rapid cooling while ensuring the strength of the ring gear.
In the aspect of this section, the dimension Lr in the radial direction and the dimension Lh in the height direction do not necessarily have to be the same dimension (Lr = Lh) as long as it is 2 to 4% of the outer end tip circle diameter D.

製造過程において浸炭処理後に急冷される時の熱処理変形を抑制することが可能なリングギヤ及びその製造方法を提供することができる。 It is possible to provide a ring gear capable of suppressing heat treatment deformation when rapidly cooled after carburizing in the manufacturing process, and a manufacturing method thereof.

本発明の一実施形態を図１〜図５に基づいて説明する。なお、上述した従来のリングギヤ２１と同一あるいは相当の構成要素には同一の名称及び符号を付与する。
図１に示されるように、本実施形態のリングギヤ１は、取付面２と外周面８との角部に環状の段差９を形成して、段差９と取付面２との間に稜部１０（以下、取付面側稜部１０という）を形成すると共に、段差９と外周面８との間に稜部１１（以下、外周面側稜部１１という）を形成する。これにより、製造工程においてリングギヤ１の急冷時における冷却速度の差を緩和させて、急冷時における熱処理変形を防止するものである。また、本実施形態のリングギヤ１は、段差９の半径方向（図１における左右方向）の寸法Lr及び高さ方向の寸法Lhを、外端歯先円直径Dの２〜４％に設定することにより、当該リングギヤ１の強度を確保しつつ、急冷時における熱処理変形を防止するものである。 An embodiment of the present invention will be described with reference to FIGS. In addition, the same name and code | symbol are provided to the same or equivalent component as the conventional ring gear 21 mentioned above.
As shown in FIG. 1, the ring gear 1 of the present embodiment forms an annular step 9 at the corner between the mounting surface 2 and the outer peripheral surface 8, and a ridge 10 between the step 9 and the mounting surface 2. (Hereinafter referred to as the mounting surface side ridge portion 10) and a ridge portion 11 (hereinafter referred to as the outer peripheral surface side ridge portion 11) are formed between the step 9 and the outer peripheral surface 8. Thereby, the difference in the cooling rate when the ring gear 1 is rapidly cooled in the manufacturing process is alleviated to prevent heat treatment deformation during the rapid cooling. In the ring gear 1 of the present embodiment, the dimension Lr in the radial direction (left-right direction in FIG. 1) and the dimension Lh in the height direction of the step 9 are set to 2 to 4% of the outer end tip diameter D. Thus, heat treatment deformation during rapid cooling is prevented while securing the strength of the ring gear 1.

次に、本実施形態のリングギヤ１の製造方法を説明する。まず、素材を鍛造してリングギヤ１を成形する（成形工程）。この成形工程において、成形品（リングギヤ１）の取付面２と外周面８との角部に環状の段差９が成形される。この環状の段差９によって、成形品（リングギヤ１）に、取付面側稜部１０及び外周面側稜部１１が形成される。なお、本実施形態では、成形品（リングギヤ１）の取付面側稜部１０の角度、すなわち、段差９の取付面側壁面９ａと取付面２とがなす角度が90°（直角）に設定されると共に、段差９の取付面側壁面９ａと外周面側壁面９ｂとなす角度が90°（直角）に設定される。そして、成形工程により得られた成形品（リングギヤ１）をハイポイド歯切り加工する（機械加工工程）。なお、本実施形態では、機械加工工程により得られるリングギヤ１の外端歯先円直径Dを200mmとする。また、リングギヤ１の段差９の半径方向の寸法Lrを4mm（外端歯先円直径Dの20％）、当該段差９の高さ方向の寸法Lhを4mm（外端歯先円直径Dの20％）とする。 Next, the manufacturing method of the ring gear 1 of this embodiment is demonstrated. First, the ring gear 1 is formed by forging the material (forming step). In this molding step, an annular step 9 is formed at the corner between the mounting surface 2 and the outer peripheral surface 8 of the molded product (ring gear 1). By this annular step 9, the mounting surface side ridge portion 10 and the outer peripheral surface side ridge portion 11 are formed in the molded product (ring gear 1). In the present embodiment, the angle of the mounting surface side ridge portion 10 of the molded product (ring gear 1), that is, the angle formed by the mounting surface side wall surface 9a of the step 9 and the mounting surface 2 is set to 90 ° (right angle). In addition, the angle between the mounting surface side wall surface 9a and the outer peripheral surface side wall surface 9b of the step 9 is set to 90 ° (right angle). Then, the molded product (ring gear 1) obtained by the molding process is subjected to hypoid gear cutting (machining process). In the present embodiment, the outer end tip diameter D of the ring gear 1 obtained by the machining process is set to 200 mm. Further, the radial dimension Lr of the step 9 of the ring gear 1 is 4 mm (20% of the outer end tip diameter D), and the height Lh of the step 9 is 4 mm (the outer end tip diameter D of 20). %).

次に、図２に示されるように、機械加工後のリングギヤ１を950℃に加熱して浸炭処理後、油冷によって130℃の温度まで急冷する。そして、所定時間の経過後、当該リングギヤ１を150℃の温度で所定時間焼き戻す（熱処理工程）。 Next, as shown in FIG. 2, the machined ring gear 1 is heated to 950 ° C., carburized, and then rapidly cooled to a temperature of 130 ° C. by oil cooling. Then, after a predetermined time has elapsed, the ring gear 1 is tempered at a temperature of 150 ° C. for a predetermined time (heat treatment step).

次に、本実施形態の作用を説明する。図３は、リングギヤ１の取付面２の振れ（熱処理変形）を、段差９の半径方向の寸法Lr及び高さ方向の寸法Lhを変えて相対的に示したものである。なお、ここでは、段差９の半径方向の寸法Lrと高さ方向の寸法Lhとを同一として（Lr＝Lh）、以降、段差寸法Lという。
この図に示されるように、段差寸法Lが外端歯先円直径Dの20％（L＝0.02D）であるリングギヤ１の場合、取付面２の振れは最大で0.05mmである。また、段差寸法Lが外端歯先円直径Dの40％（L＝0.04D）であるリングギヤ１の場合、取付面２の振れは最大で0.05mm以下である。これに対して、取付面２と外周面８との角部が45°でＣ面取りされている従来のリングギヤ２１の場合、取付面２の振れは最大で0.12mmあり、このようなリングギヤ２１をディファレンシャルに用いた場合、振動や騒音が発生する虞がある。 Next, the operation of this embodiment will be described. FIG. 3 relatively shows the deflection (heat treatment deformation) of the mounting surface 2 of the ring gear 1 by changing the radial dimension Lr and the height dimension Lh of the step 9. Here, the dimension Lr in the radial direction and the dimension Lh in the height direction of the step 9 are the same (Lr = Lh), and are hereinafter referred to as a step dimension L.
As shown in this figure, in the case of the ring gear 1 in which the step size L is 20% (L = 0.02D) of the outer end tip circle diameter D, the deflection of the mounting surface 2 is 0.05 mm at the maximum. Further, in the case of the ring gear 1 in which the step dimension L is 40% (L = 0.04D) of the outer end addendum circle diameter D, the runout of the mounting surface 2 is 0.05 mm or less at the maximum. On the other hand, in the case of the conventional ring gear 21 in which the corners of the mounting surface 2 and the outer peripheral surface 8 are chamfered at 45 °, the deflection of the mounting surface 2 is 0.12 mm at the maximum. When used for a differential, vibration and noise may occur.

一方、段差寸法Lが外端歯先円直径Dの60％（L＝0.06D）であるリングギヤ１の場合、図３に示されるように、取付面２の振れは最大で0.05mm以下であるが、外端部側肉厚が薄くなることから、図４に示されるように、ピッチ誤差が最大で0.04mmあり、ギヤ精度が著しく低下する結果となり、このリングギヤ１をディファレンシャルに用いた場合、振動や騒音が発生する虞がある。 On the other hand, in the case of the ring gear 1 in which the step size L is 60% (L = 0.06D) of the outer end tip diameter D, as shown in FIG. 3, the runout of the mounting surface 2 is 0.05 mm or less at maximum. However, since the outer end side thickness is reduced, as shown in FIG. 4, the maximum pitch error is 0.04 mm, resulting in a significant reduction in gear accuracy. When this ring gear 1 is used as a differential, There is a risk of vibration and noise.

ここで、従来のリングギヤ２１（図９参照）では、外端部側稜部５及び内端部側稜部７の急冷時における冷却速度が、他の部分、特に、取付面２に対して高かったため、浸炭処理後の急冷時における冷却速度がばらついてしまい熱処理変形を生じていた。本実施形態のリングギヤ１では、取付面２と外周面８との角部に環状の段差９を形成することで、段差９と取付面２との間に取付面側稜部１０を形成すると共に、段差９と外周面８との間に外周面側稜部１１を形成して、急冷時における冷却速度の差を緩和、特に、取付面２と急冷時における冷却速度が他の部分に対して高い外端部側稜部５及び内端部側稜部７との冷却速度の差を緩和させたので、取付面２の収縮及び膨張のタイミングを、外端部側稜部５及び内端部側稜部７のタイミングに合せることができ、急冷時における熱処理変形を防止することができる。 Here, in the conventional ring gear 21 (see FIG. 9), the cooling rate at the time of rapid cooling of the outer end side ridge portion 5 and the inner end portion side ridge portion 7 is higher than that of other portions, particularly the mounting surface 2. For this reason, the cooling rate at the time of quenching after the carburizing process varies, resulting in heat treatment deformation. In the ring gear 1 of the present embodiment, the annular surface step 9 is formed at the corner between the attachment surface 2 and the outer peripheral surface 8, thereby forming the attachment surface side ridge portion 10 between the step 9 and the attachment surface 2. The outer peripheral surface side ridge portion 11 is formed between the step 9 and the outer peripheral surface 8 to alleviate the difference in the cooling rate during the rapid cooling, in particular, the cooling rate during the rapid cooling with respect to the mounting surface 2 relative to other parts. Since the difference in cooling rate between the high outer end side ridge part 5 and the inner end part side ridge part 7 was alleviated, the contraction and expansion timings of the mounting surface 2 were determined by the outer end side ridge part 5 and the inner end part. It is possible to match the timing of the side ridge 7 and to prevent heat treatment deformation during rapid cooling.

具体的には、図５に示されるように、本実施形態のリングギヤ１は、急冷時の初期段階（図５（Ａ）参照）では、取付面２側に配置される取付面側稜部１０及び外周面側稜部１１と、歯先側に配置される外端部側稜部５及び内端部側稜部７とが同一の冷却速度で冷却されて同一のタイミングで収縮する。次の段階（図５（Ｂ）参照）では、取付面側稜部１０及び外周面側稜部１１と、外端部側稜部５及び内端部側稜部７とが同一のタイミングで膨張（組織変態）すると共に、これら稜部５，７，１０，１１によって囲まれるリングギヤ１の内側の部分が収縮を開始する。さらに、最終段階（図５（Ｃ）参照）では、稜部５，７，１０，１１によって囲まれるリングギヤ１の内側の部分のみが膨張（組織変態）する。このように、急冷時における冷却速度の差を緩和させて、取付面側稜部１０及び外周面側稜部１１と、外端部側稜部５及び内端部側稜部７との収縮及び膨張のタイミングを合せることで、リングギヤ１の熱処理変形を防止することができる。 Specifically, as shown in FIG. 5, the ring gear 1 of the present embodiment has a mounting surface side ridge portion 10 arranged on the mounting surface 2 side in the initial stage of rapid cooling (see FIG. 5A). And the outer peripheral surface side ridge part 11 and the outer end part side ridge part 5 and the inner end part side ridge part 7 arranged on the tooth tip side are cooled at the same cooling rate and contract at the same timing. In the next stage (see FIG. 5B), the mounting surface side ridge portion 10 and the outer peripheral surface side ridge portion 11, and the outer end portion side ridge portion 5 and inner end portion side ridge portion 7 expand at the same timing. (Structural transformation) and the inner part of the ring gear 1 surrounded by the ridges 5, 7, 10, 11 starts to contract. Furthermore, in the final stage (see FIG. 5C), only the inner part of the ring gear 1 surrounded by the ridges 5, 7, 10, 11 expands (tissue transformation). Thus, by reducing the difference in cooling rate during rapid cooling, shrinkage of the mounting surface side ridge portion 10 and the outer peripheral surface side ridge portion 11, the outer end portion side ridge portion 5 and the inner end portion side ridge portion 7 and By matching the expansion timing, the heat treatment deformation of the ring gear 1 can be prevented.

この実施形態では以下の効果を奏する。
本実施形態によれば、リングギヤ１の取付面２と外周面８との角部に環状の段差９を形成したので、段差９と取付面２との間に取付面側稜部１０が形成されると共に、段差９と外周面８との間に外周面側稜部１１が形成される。これにより、浸炭処理後の急冷時における冷却速度の差が緩和、特に、取付面２と急冷時における冷却速度が他の部分に対して高い外端部側稜部５及び内端部側稜部７との冷却速度の差が緩和され、取付面２の収縮及び膨張のタイミングを、外端部側稜部５及び内端部側稜部７のタイミングに合せることができ、急冷時における熱処理変形を防止することができる。
また、本実施形態によれば、リングギヤ１の段差９は、半径方向の寸法Lr及び高さ方向の寸法Lhが、外端歯先円直径Dの２〜４％に設定されるので、リングギヤ１の強度を確保しつつ、急冷時におけるリングギヤ１の熱処理変形を防ぐことができる。 This embodiment has the following effects.
According to the present embodiment, since the annular step 9 is formed at the corner between the mounting surface 2 and the outer peripheral surface 8 of the ring gear 1, the mounting surface side ridge portion 10 is formed between the step 9 and the mounting surface 2. In addition, an outer peripheral surface side ridge portion 11 is formed between the step 9 and the outer peripheral surface 8. Thereby, the difference in the cooling rate at the time of quenching after the carburizing treatment is alleviated, and in particular, the outer end side ridge portion 5 and the inner end portion side ridge portion which are higher in the cooling rate at the time of quenching than the mounting surface 2. 7 is mitigated, and the timing of contraction and expansion of the mounting surface 2 can be matched with the timing of the outer end side ridge portion 5 and the inner end side ridge portion 7, and heat treatment deformation during rapid cooling Can be prevented.
Further, according to the present embodiment, the step 9 of the ring gear 1 has the radial dimension Lr and the height dimension Lh set to 2 to 4% of the outer end tooth tip diameter D. It is possible to prevent the heat treatment deformation of the ring gear 1 during rapid cooling while securing the strength.

なお、実施形態は上記に限定されるものではなく、例えば次のように構成してもよい。
図６に示されるように、取付面２と軸孔内周面１２との角部に環状の段差９を形成することにより、段差９と取付面２との間に稜部１３を形成すると共に、段差９と軸孔内周面１２との間に稜部１４を形成してリングギヤ１を構成してもよい。この場合、取付面２と外周面８との角部に段差９を形成した本実施形態のリングギヤ１同様、急冷時における冷却速度の差が緩和されて、急冷時における熱処理変形を防止することができる。この場合も、本実施形態のリングギヤ１同様、段差９の半径方向（図６における左右方向）の寸法Lr及び高さ方向の寸法Lhを、外端歯先円直径Dの２〜４％に設定することにより、当該リングギヤ１の強度を確保しつつ、急冷時における熱処理変形を防止することができる。
本実施形態では、リングギヤ１の取付面側稜部１０の角度、すなわち、段差９の取付面側壁面９ａと取付面２とがなす角度が90°（直角）に設定されると共に、段差９の取付面側壁面９ａと外周面側壁面９ｂとなす角度が90°（直角）に設定されたが、図７に示されるように、これらの角度を90°以上、例えば、110°に設定して、急冷時における冷却速度を調節してもよい。
本実施形態では、段差９の壁面９ａ，９ｂが平面によって構成されるが、図８に示されるように、段差壁面９ｃを曲面によって構成してもよい。この場合、段差壁面９ｃと取付面２との角部、及び段差壁面９ｃと外周面８との角部の角度は、鋭角であることが望ましい。 In addition, embodiment is not limited above, For example, you may comprise as follows.
As shown in FIG. 6, by forming an annular step 9 at the corner between the mounting surface 2 and the shaft hole inner peripheral surface 12, a ridge 13 is formed between the step 9 and the mounting surface 2. The ring gear 1 may be configured by forming a ridge 14 between the step 9 and the inner peripheral surface 12 of the shaft hole. In this case, similar to the ring gear 1 of the present embodiment in which the step 9 is formed at the corners of the mounting surface 2 and the outer peripheral surface 8, the difference in cooling rate during quenching is alleviated, and heat treatment deformation during quenching can be prevented. it can. In this case as well, like the ring gear 1 of the present embodiment, the radial dimension Lr (horizontal direction in FIG. 6) and the height dimension Lh of the step 9 are set to 2 to 4% of the outer end tip diameter D. By doing so, it is possible to prevent heat treatment deformation during rapid cooling while ensuring the strength of the ring gear 1.
In the present embodiment, the angle of the mounting surface side ridge portion 10 of the ring gear 1, that is, the angle formed by the mounting surface side wall surface 9 a of the step 9 and the mounting surface 2 is set to 90 ° (right angle). The angle between the mounting surface side wall surface 9a and the outer peripheral surface side wall surface 9b is set to 90 ° (right angle), but as shown in FIG. 7, these angles are set to 90 ° or more, for example, 110 °. The cooling rate during rapid cooling may be adjusted.
In the present embodiment, the wall surfaces 9a and 9b of the step 9 are constituted by flat surfaces, but the step wall surface 9c may be constituted by a curved surface as shown in FIG. In this case, it is desirable that the corners of the step wall surface 9c and the mounting surface 2 and the corners of the step wall surface 9c and the outer peripheral surface 8 are acute angles.

本実施形態のリングギヤの軸断面の一部を示す図である。It is a figure which shows a part of axial cross section of the ring gear of this embodiment. 熱処理工程の説明図である。It is explanatory drawing of a heat processing process. リングギヤの取付面の振れ（熱処理変形）を、段差寸法Lを変えて相対的に示した図である。FIG. 6 is a diagram relatively showing runout (heat treatment deformation) of the ring gear mounting surface while changing the step size L; リングギヤのピッチ誤差を、段差寸法Lを変えて相対的に示した図である。FIG. 6 is a diagram relatively showing a ring gear pitch error by changing a step size L; 本実施形態のリングギヤの浸炭処理後の急冷時における内部の様子を段階的に示した図である。It is the figure which showed the mode of the inside at the time of rapid cooling after the carburizing process of the ring gear of this embodiment in steps. 段差が取付面と軸孔内周面との角部に形成される他の実施形態のリングギヤの軸断面の一部を示す図である。It is a figure which shows a part of axial cross section of the ring gear of other embodiment in which a level | step difference is formed in the corner | angular part of an attachment surface and an axial peripheral surface. 他の実施形態のリングギヤの軸断面の一部を示す図で、特に、取付面側稜部の角度が鈍角（110°）であるリングギヤの軸断面を示す図である。It is a figure which shows a part of axial cross section of the ring gear of other embodiment, and is a figure which especially shows the axial cross section of the ring gear whose angle of a mounting surface side ridge part is an obtuse angle (110 degrees). 他の実施形態のリングギヤの軸断面の一部を示す図で、特に、段差壁面が曲面によって構成される段部を有するリングギヤの軸断面を示す図である。It is a figure which shows a part of axial cross section of the ring gear of other embodiment, and is a figure which especially shows the axial cross section of the ring gear which has the step part by which a level | step difference wall surface is comprised by a curved surface. 従来のリングギヤの浸炭処理後の急冷時における内部の様子を段階的に示した図である。It is the figure which showed the mode of the inside at the time of rapid cooling after the carburizing process of the conventional ring gear in steps.

Explanation of symbols

１リングギヤ、２取付面、８外周面、９段差、１０取付面側稜部、１１外周面側稜部 1 ring gear, 2 mounting surface, 8 outer peripheral surface, 9 steps, 10 mounting surface side ridge, 11 outer peripheral surface ridge

Claims

A ring gear that is rapidly cooled after a carburizing process in a manufacturing process, wherein an annular step is formed at a corner between an attachment surface and an outer peripheral surface.

A ring gear that is rapidly cooled after carburizing treatment in a manufacturing process, wherein an annular step is provided at a corner between the mounting surface and the inner peripheral surface of the shaft hole.

3. The ring gear according to claim 1, wherein the annular step has a dimension Lr in the radial direction and a dimension Lh in the height direction that is 2 to 4% of the outer end tip diameter D. 4.

An annular step is formed at the corner between the ring gear mounting surface and the outer peripheral surface, where the radial dimension Lr and the height dimension Lh are determined based on the diameter D of the outer end tooth tip circle. A method of manufacturing a ring gear, characterized in that the ring gear is rapidly cooled after carburizing.

At the corner of the ring gear mounting surface and the inner peripheral surface of the shaft hole, an annular step having a radial dimension Lr and a height dimension Lh determined on the basis of the outer end tooth tip diameter D is processed. A ring gear manufacturing method, comprising: quenching a ring gear with a step processed after carburizing treatment.

The ring gear is processed with the annular step having a radial dimension Lr and a height dimension Lh of 2 to 4% of the outer end tip circle diameter D, and the ring gear is quenched after carburizing. The method for manufacturing a ring gear according to claim 4 or 5, characterized in that: