WO2014188838A1

WO2014188838A1 - Method for producing outside joint member for use in constant-velocity universal joint, and intermediate forged product to be made into outside joint member

Info

Publication number: WO2014188838A1
Application number: PCT/JP2014/061420
Authority: WO
Inventors: 義忠郁山; 訓弘芝田; 英樹布川
Original assignee: Ntn株式会社
Priority date: 2013-05-22
Filing date: 2014-04-23
Publication date: 2014-11-27
Also published as: JP2014226691A

Abstract

A method for producing an outside joint member (1) which has a cylindrical cup section (2) having a floor and open on one end, and which has a plurality of tracking grooves (5) provided on the inner-diameter surface (4) of the cup section (2) which extend in the axial direction, the outside joint member (1) being produced by executing steps including the following: a pre-forging step for molding a rod-shaped material into an intermediate forged product (21) which has a cylindrical cup section (22) having a floor and having tracking grooves roughly formed on the inner-diameter surface thereof; and an ironing step for molding the intermediate forged product (21) into a final forged product (11) having finished tracking grooves (5). Furthermore, the pre-forging step involves, in advance of proceeding with the ironing treatment during the ironing step thereafter, forming the intermediate forged product (21) in a manner such that a surface (24) having an increasing diameter in the direction in which the plastic deformation margin of the cup section (22) gradually increases is positioned on the outer-diameter surface (23) of the cup section (22).

Description

等速自在継手用外側継手部材の製造方法および外側継手部材に加工される中間鍛造品Manufacturing method of outer joint member for constant velocity universal joint and intermediate forged product processed into outer joint member

　本発明は、例えば、自動車、航空機、船舶および各種産業機械などの動力伝達系において使用され、駆動側と従動側の二軸間で回転動力を等速で伝達する等速自在継手用の外側継手部材の製造方法、および外側継手部材に加工される中間鍛造品に関する。 The present invention is used in, for example, power transmission systems of automobiles, aircraft, ships, various industrial machines, etc., and is an outer joint for a constant velocity universal joint that transmits rotational power at a constant speed between two axes of a driving side and a driven side. The present invention relates to a member manufacturing method and an intermediate forged product processed into an outer joint member.

　周知のように、等速自在継手は、角度変位のみを許容する固定式等速自在継手と、角度変位および軸方向変位を許容する摺動式等速自在継手とに大別される。等速自在継手は、固定式であるか摺動式であるかに関わらず、一端が開口した有底筒状のカップ部を有し、カップ部の内径面に複数のトラック溝が設けられた外側継手部材と、外側継手部材のカップ部の内周に収容される内側継手部材やトルク伝達部材などの継手内部部品とを主要な構成部材として備える。これら継手構成部材のうち、外側継手部材は、切削や旋削などの機械加工、および／又は鍛造などの塑性加工を駆使して製造されるが、生産効率や歩留の向上を図るため、可能な限りにおいて塑性加工を採用する場合が多い。 As is well known, constant velocity universal joints are roughly classified into fixed constant velocity universal joints that allow only angular displacement and sliding constant velocity universal joints that allow angular displacement and axial displacement. Regardless of whether the constant velocity universal joint is a fixed type or a sliding type, the constant velocity universal joint has a bottomed cylindrical cup portion that is open at one end, and a plurality of track grooves are provided on the inner diameter surface of the cup portion. An outer joint member and joint inner parts such as an inner joint member and a torque transmission member housed in the inner periphery of the cup portion of the outer joint member are provided as main constituent members. Of these joint components, the outer joint member is manufactured by making full use of machining such as cutting and turning and / or plastic working such as forging. However, it is possible to improve production efficiency and yield. In many cases, plastic working is often used.

　一例として、下記の特許文献１には、摺動式等速自在継手の一種であるトリポード型等速自在継手の外側継手部材であって、内径面に軸方向に延びる複数のトラック溝が設けられた有底筒状のカップ部と、カップ部の底部から軸方向に延びる軸部とを一体に備えるものを、各種鍛造工程を経て製造する方法が記載されている。具体的には、棒状素材に据え込み加工や押し出し加工などを順次施すことにより、棒状素材を、内径面にトラック溝が粗成形されたカップ状部を有する中間鍛造品に成形する前鍛造工程と、中間鍛造品のカップ状部を、その内周及び外周にそれぞれ配置されるパンチ（しごきパンチ）及びダイス（しごきダイス）の成形面に倣うように塑性変形させることにより、中間鍛造品を、内径面に仕上がり形状のトラック溝を有する最終鍛造品に成形するしごき工程とを含む外側継手部材の製造方法である。 As an example, Patent Document 1 below is an outer joint member of a tripod type constant velocity universal joint which is a kind of sliding type constant velocity universal joint, and a plurality of track grooves extending in the axial direction are provided on an inner diameter surface. In addition, there is described a method for manufacturing a product having a bottomed cylindrical cup part and a shaft part extending in the axial direction from the bottom part of the cup part through various forging processes. Specifically, a pre-forging step of forming the rod-shaped material into an intermediate forged product having a cup-shaped portion having a track groove roughly formed on the inner diameter surface by sequentially performing upsetting and extrusion processing on the rod-shaped material, and The intermediate forged product has an inner diameter by plastically deforming the cup-shaped portion of the intermediate forged product so as to follow the molding surface of the punch (ironing die) and the die (ironing die) disposed on the inner periphery and outer periphery thereof, respectively. And an ironing process for forming a final forged product having a finished track groove on the surface.

　なお、棒状素材を中間鍛造品に成形するための前鍛造（据え込みや押し出し等）は、温間以上の温度領域（温間、亜熱間又は熱間）で実行される場合が多い。その主な理由として、前鍛造工程の各段階では、棒状のワークを比較的大きく塑性変形させる必要があるために、冷間では必要とされる塑性変形量を確保することが難しい、ということが挙げられる。これに対し、しごき加工は冷間で実行される場合が多い。しごき加工では、概ね、カップ状部の筒部を軸方向に伸長変形させることができれば足り、据え込みや押し出しに比べれば、ワーク（中間鍛造品）や金型の温度が低くても必要とされる塑性変形量を確保し得ること、また、高精度の最終鍛造品、ひいては外側継手部材を得る上で有利となるからである。 Note that pre-forging (upsetting, extrusion, etc.) for forming a rod-shaped material into an intermediate forged product is often performed in a temperature range (warm, sub-hot or hot) that is higher than warm. The main reason is that at each stage of the pre-forging process, it is necessary to relatively large plastically deform the rod-shaped workpiece, so that it is difficult to ensure the amount of plastic deformation required in the cold. Can be mentioned. On the other hand, ironing is often performed cold. In ironing, it is generally sufficient that the cylindrical part of the cup-shaped part can be extended and deformed in the axial direction. Compared to upsetting and extrusion, it is required even if the temperature of the workpiece (intermediate forging product) or the mold is low. This is because it is advantageous to secure a sufficient amount of plastic deformation and to obtain a highly accurate final forged product and, in turn, an outer joint member.

特開２００２－２１３４７６号公報JP 2002-213476 A

　ところで、上記製造方法において、図８に示すように、中間鍛造品１００に対するしごき加工を、カップ状部１０１を構成する筒部１０２の肉厚減少率δ［％］が比較的大きくなるように（例えばδ≧１５％となるように）実行すると、同図中の右側の図に示すように、最終鍛造品１１０のうち、特にカップ状部１１１を構成する筒部１１２の基端部に亀裂１２０が形成される、カップ状部１１１の底部１１３が大きく変形する（軸直交平面に対するカップ状部１１３外底面の母線角度θが、しごき加工前のカップ状部１０３のそれに比べて著しく大きくなる）などといった事態の発生確率が高くなる。筒部１１２に亀裂１２０が形成されると、最終鍛造品１１０を廃棄処分せざるを得なくなることから歩留が低下し、カップ状部１１１の底部１１３が大きく変形すると、底部１１３に大幅な仕上げ加工を施す必要が生じて加工コストが増大する。なお、肉厚減少率δとは、しごき加工前における所定部位の肉厚をｔ１、しごき加工後における同部の肉厚をｔ２としたとき、δ＝｛（ｔ１―ｔ２）／ｔ１｝×１００の関係式から算出される百分率である。以下の説明において「肉厚減少率」という場合も同様である。 In the above manufacturing method, as shown in FIG. 8, the ironing process for the intermediate forged product 100 is performed so that the thickness reduction rate δ [%] of the cylindrical portion 102 constituting the cup-shaped portion 101 is relatively large ( When executed (for example, δ ≧ 15%), as shown in the diagram on the right side of the figure, a crack 120 is formed at the proximal end portion of the cylindrical portion 112 constituting the cup-shaped portion 111 in the final forged product 110 in particular. The bottom 113 of the cup-shaped part 111 is greatly deformed (the generatrix angle θ of the outer bottom surface of the cup-shaped part 113 with respect to the axis perpendicular to the axis is significantly larger than that of the cup-shaped part 103 before ironing). The occurrence probability of such a situation becomes high. If the crack 120 is formed in the cylindrical portion 112, the final forged product 110 must be disposed of, so that the yield decreases, and when the bottom 113 of the cup-shaped portion 111 is greatly deformed, the bottom 113 is greatly finished. Processing needs to be performed and processing costs increase. Note that the thickness reduction rate δ is δ = {(t1−t2) / t1} × 100, where t1 is the thickness of a predetermined portion before ironing and t2 is the thickness of the same portion after ironing. It is a percentage calculated from the relational expression. The same applies to the case of “thickness reduction rate” in the following description.

　そこで、中間鍛造品に対するしごき加工を、筒部の肉厚減少率δが１５％を超えないように実行することを試みた。ところが、しごき加工に伴う肉厚減少率δが小さくなるほど、しごき加工に伴う筒部の伸長変形量が短くなる（塑性変形量が少なくなる）ことから、必要とされるトラック溝長さを確保できない、しごき加工に伴う加工硬化を十分に得ることができず必要とされる機械的強度を確保することができない、などといった不具合が生じ易くなった。 Therefore, an attempt was made to execute ironing on the intermediate forged product so that the thickness reduction rate δ of the tube portion does not exceed 15%. However, the smaller the thickness reduction rate δ associated with the ironing process, the shorter the amount of expansion and deformation of the cylinder part associated with the ironing process (the smaller the plastic deformation amount), so the required track groove length cannot be ensured. However, the work hardening associated with the ironing process cannot be sufficiently obtained, and the required mechanical strength cannot be ensured.

　このような問題は、例えば前鍛造工程において、カップ状部の深さ寸法（筒部の軸方向寸法）が長寸の中間鍛造品を成形することによって可及的に解消し得るものと考えた。しかしながら、このようにすると、前鍛造工程の各ステップにおけるワークの変形量を増加させる必要が生じるため、前鍛造工程の各ステップで使用する鍛造金型への負担が大きくなって金型寿命が短くなる。特に、前鍛造を、上記したように温間以上の温度領域で実行するような場合には、ただでさえ鍛造金型の寿命が短くなり易い。具体例を挙げるならば、熱間鍛造金型の使用可能回数は、冷間鍛造金型のそれに比べて数分の一～数十分の一程度とされる。従って、上記の手法では、金型費用の増大や生産効率の低下が避けられず、鍛造加工を採用することによるコストメリットを十分に享受できなくなる。 It was considered that such a problem can be solved as much as possible by forming an intermediate forging product in which the depth dimension of the cup-shaped part (the axial dimension of the cylinder part) is long in the pre-forging process, for example. . However, if it does in this way, since it will be necessary to increase the deformation amount of the workpiece | work in each step of a pre-forging process, the burden to the forge metal mold | die used at each step of a pre-forging process will become large, and metal mold | die lifetime will be short. Become. In particular, when pre-forging is performed in the temperature range above the warm as described above, the life of the forging die is likely to be shortened. As a specific example, the number of times that the hot forging die can be used is set to be a fraction of 1 to several tenths that of the cold forging die. Therefore, in the above method, an increase in mold cost and a decrease in production efficiency cannot be avoided, and the cost merit by adopting forging cannot be fully enjoyed.

　以上の実情に鑑み、本発明の課題は、所望の形状や強度を具備した外側継手部材を低コストに製造可能とし、これにより、等速自在継手の低コスト化に寄与することにある。 In view of the above circumstances, an object of the present invention is to make it possible to manufacture an outer joint member having a desired shape and strength at low cost, thereby contributing to cost reduction of a constant velocity universal joint.

　本発明者らは鋭意研究を重ねた結果、上述した種々の問題は、図８に示したように、中間鍛造品１００のカップ状部１０１を構成する筒部１０２の肉厚が、軸方向全長に亘って概ね均一とされており（筒部１０２の外径面が軸線と平行なストレート面に形成されており）、しごきダイスに対する筒部１０２の圧入代（筒部１０２の塑性変形代）がしごき加工開始～完了までほぼ一定とされること、すなわち、しごき加工によるカップ状部１０１（筒部１０２）の肉厚減少率がカップ状部１０１の軸方向全域で概ね等しいことから、肉厚減少率を上げると、筒部１０２の基端部に応力集中が生じること、を主たる要因として発生し易くなるものと考えた。そこで、ダイスに対するカップ状部の圧入代（カップ状部の塑性変形代）が徐々に増加するようにしごき加工を実行すれば、上述した種々の問題発生を可及的に防止し得ることを見出し、本発明を完成するに至った。 As a result of repeated studies by the inventors, the above-described various problems are caused by the fact that the thickness of the cylindrical portion 102 constituting the cup-shaped portion 101 of the intermediate forged product 100 is the total axial length as shown in FIG. (The outer diameter surface of the cylindrical portion 102 is formed on a straight surface parallel to the axis), and the allowance for press fitting the cylindrical portion 102 to the ironing die (plastic deformation allowance of the cylindrical portion 102) is Since the ironing process is almost constant from the start to the completion, that is, the thickness reduction rate of the cup-shaped part 101 (cylinder part 102) by the ironing process is substantially the same in the entire axial direction of the cup-shaped part 101. When the rate is increased, it is considered that stress concentration is likely to occur at the proximal end portion of the cylindrical portion 102, which is likely to occur mainly. Accordingly, it has been found that the above-described various problems can be prevented as much as possible by performing ironing so that the press-fitting allowance of the cup-shaped part to the die (plastic deformation allowance of the cup-shaped part) gradually increases. The present invention has been completed.

　すなわち、上記の課題を解決するために創案された本発明は、一端が開口した有底筒状のカップ部を有し、カップ部の内径面に軸方向に延びる複数のトラック溝が設けられた等速自在継手用外側継手部材の製造方法であって、棒状素材を、内径面にトラック溝が粗成形された有底筒状のカップ状部を有する中間鍛造品に成形する前鍛造工程と、内周にパンチが挿入された中間鍛造品のカップ状部に対し、その外径側に配置したダイスをカップ状部の底部側から開口側に向けて圧入状態で相対移動させてカップ状部を塑性変形させることにより、中間鍛造品を、内径面に仕上がり形状のトラック溝を有する最終鍛造品に成形するしごき工程とを含み、前鍛造工程では、その後のしごき工程で上記の相対移動が進行するのに伴って、カップ状部の塑性変形代を徐々に増加させる方向の拡径面がカップ状部の外径面に設けられた中間鍛造品を成形することを特徴とする。 That is, in order to solve the above problems, the present invention has a bottomed cylindrical cup portion that is open at one end, and a plurality of track grooves extending in the axial direction are provided on the inner diameter surface of the cup portion. A method for producing an outer joint member for a constant velocity universal joint, wherein a rod-shaped material is formed into an intermediate forged product having a bottomed cylindrical cup-shaped portion in which a track groove is roughly formed on an inner diameter surface; and With respect to the cup-shaped part of the intermediate forged product in which the punch is inserted in the inner periphery, the die arranged on the outer diameter side is relatively moved in the press-fitted state from the bottom side of the cup-shaped part toward the opening side, and the cup-shaped part is moved. And an ironing step of forming the intermediate forging product into a final forging product having a track groove having a finished shape on the inner diameter surface by plastic deformation, and in the pre-forging step, the relative movement proceeds in the subsequent ironing step. With the cup-shaped part Wherein the diameter expansion surface in a direction to gradually increase the plastic deformation margin to molding the intermediate forged product provided outside diameter surface of the cup-shaped portion.

　しごき工程で使用するダイスの内径面に設けられる成形面の横断面形状は、通常、外側継手部材を構成するカップ部外周の横断面形状に概ね対応している。このため、ダイスの成形面形状に変更を加えると、大幅な後加工が必要になるおそれが高まる他、外側継手部材の機能・性能に影響を及ぼすおそれがあることから好ましくない。そこで、本発明では、前鍛造工程で成形する中間鍛造品の形状に工夫を凝らすことで上記課題の解決を図った。具体的には、前鍛造工程で成形する中間鍛造品を、そのカップ状部の外径面に、前鍛造工程後のしごき工程でダイスと中間鍛造品のカップ状部の圧入状態での相対移動（しごき加工）が進行するのに伴って、カップ状部の塑性変形代を徐々に増加させる方向の拡径面が設けられたものにすることとした。 The cross-sectional shape of the molding surface provided on the inner diameter surface of the die used in the ironing process generally corresponds generally to the cross-sectional shape of the outer periphery of the cup portion constituting the outer joint member. For this reason, it is not preferable to change the shape of the molding surface of the die because it may increase the possibility of significant post-processing and may affect the function and performance of the outer joint member. Therefore, in the present invention, the above-described problems have been solved by contriving the shape of the intermediate forged product formed in the pre-forging process. Specifically, the intermediate forged product formed in the pre-forging process is moved relative to the outer diameter surface of the cup-shaped part in the press-fitted state of the die and the cup-shaped part of the intermediate forged product in the ironing process after the pre-forging process. As the ironing process progresses, a diameter-enlarged surface in a direction that gradually increases the plastic deformation allowance of the cup-shaped portion is provided.

　この場合、特に、上記の拡径面をカップ状部の底部側に設けておけば、しごき加工の初期段階におけるダイスに対するカップ状部の圧入代、すなわちカップ状部の塑性変形量（しごき加工量）を少なくすることができる。これにより、しごき加工に伴って、特にカップ状部の筒部の基端部付近に大きな応力集中が生じてカップ状部に亀裂が形成されるのを、また、底部が大きく変形するのを可及的に防止することが可能となり、歩留の向上及び仕上げ加工の簡略化を通じて外側継手部材の製造コストを低廉化することができる。そして、しごき加工に伴う上記の不具合発生を可及的に防止することができれば、筒部の肉厚減少率が全体として高まるように、すなわち所望のトラック溝長さや加工硬化（機械的強度）を確保し得るように、中間鍛造品にしごき加工を施すことが可能となる。また、かかる態様で中間鍛造品にしごき加工を施すことができれば、前鍛造工程で成形する中間鍛造品は、そのカップ深さが短寸のもので足りる。従って、前鍛造工程で使用する鍛造金型に対する負荷を軽減することも可能となり、前鍛造金型の長寿命化を通じて、外側継手部材の製造コストを低廉化することもできる。 In this case, in particular, if the above-mentioned expanded surface is provided on the bottom side of the cup-shaped part, the allowance for press-fitting the cup-shaped part to the die in the initial stage of ironing, that is, the amount of plastic deformation of the cup-shaped part (the amount of ironing) ) Can be reduced. As a result, it is possible to cause a large stress concentration in the vicinity of the base end portion of the cylindrical portion of the cup-shaped portion due to the ironing process, so that cracks are formed in the cup-shaped portion, and the bottom portion can be greatly deformed. As a result, the manufacturing cost of the outer joint member can be reduced through improvement in yield and simplification of finishing. Then, if the above-mentioned problems associated with ironing can be prevented as much as possible, the thickness reduction rate of the cylindrical portion is increased as a whole, that is, the desired track groove length and work hardening (mechanical strength) are increased. It is possible to iron the intermediate forged product so that it can be secured. In addition, if the intermediate forged product can be ironed in such a manner, the intermediate forged product formed in the pre-forging step only needs to have a short cup depth. Accordingly, it is possible to reduce the load on the forging die used in the pre-forging step, and it is possible to reduce the manufacturing cost of the outer joint member through extending the life of the pre-forging die.

　上記の作用効果を有効に享受するための具体的手段として、前鍛造工程で成形する中間鍛造品を、カップ状部の外底面の外径端に上記拡径面の最小径部が配置されたものとすることが考えられる。より具体的には、例えば、中間鍛造品のカップ状部のうち、しごき加工前における上記の外径端（拡径面の最小径部）を含む部分の肉厚をＸａ、しごき加工後における当該部分の肉厚をＸｂとしたとき、Ｘｂ≧０．９Ｘａ（厳密には、Ｘａ＞Ｘｂ≧０．９Ｘａ）の関係式を満たすように（つまり、当該部分のしごき加工に伴う肉厚減少率δが１０％以下となるように）することが考えられる。 As a specific means for effectively enjoying the above-described effects, the intermediate forged product formed in the pre-forging step is arranged such that the minimum diameter portion of the expanded surface is disposed at the outer diameter end of the outer bottom surface of the cup-shaped portion. It can be considered. More specifically, for example, among the cup-shaped portions of the intermediate forged product, the thickness of the portion including the outer diameter end (the smallest diameter portion of the expanded surface) before ironing is Xa, and the thickness after ironing When the thickness of the portion is Xb, the thickness reduction rate δ associated with the ironing of the portion is satisfied so as to satisfy the relational expression of Xb ≧ 0.9Xa (strictly, Xa> Xb ≧ 0.9Xa). Is 10% or less).

　また、中間鍛造品を、カップ状部を構成する筒部の基端部における肉厚が、しごき工程後に１５％以上３５％以下減少するように、上記拡径面が設けられたものとすることができる。この場合、中間鍛造品は、筒部の軸方向中央部の肉厚が、しごき工程後に上記基端部よりも大きく減少するように、上記拡径面が設けられたものとするのが好ましい。より具体的には、筒部の軸方向中央部の肉厚が、しごき工程後に１５％以上６０％以下減少するように、上記拡径面が設けられたものとするのが好ましい。これにより、中間鍛造品にしごき加工を施すのに伴って、カップ状部の筒部に亀裂が形成されたり、カップ状部の底部が大きく変形したりするような事態を効果的に防止しつつ、所望のトラック溝長さ（カップ深さ）や機械的強度を有する最終鍛造品を得ることができる。 In addition, the intermediate forging product shall be provided with the above-mentioned diameter-expanded surface so that the thickness at the base end portion of the cylindrical portion constituting the cup-shaped portion is reduced by 15% or more and 35% or less after the ironing process. Can do. In this case, it is preferable that the intermediate forged product is provided with the above-described diameter-expanded surface so that the thickness of the central portion in the axial direction of the cylindrical portion is significantly reduced after the ironing process. More specifically, it is preferable that the above-described diameter-expanded surface is provided so that the thickness of the central portion in the axial direction of the cylindrical portion is reduced by 15% or more and 60% or less after the ironing process. This effectively prevents a situation in which cracks are formed in the cylindrical portion of the cup-shaped portion or the bottom of the cup-shaped portion is greatly deformed as ironing is performed on the intermediate forged product. A final forged product having a desired track groove length (cup depth) and mechanical strength can be obtained.

　以上の構成において、中間鍛造品は、カップ状部（筒部）の外径面の軸方向中央部に、上記拡径面の最大径部が配置されたものとすることができる。 In the above configuration, the intermediate forged product may be one in which the maximum diameter portion of the above-mentioned expanded surface is disposed at the axially central portion of the outer diameter surface of the cup-shaped portion (tubular portion).

　以上の構成において、しごき工程は、冷間で実行するのが望ましい。最終鍛造品の成形精度を高めることができるので、高精度の外側継手部材を低コストに製造可能とする上で有利であるからである。また、本発明に係る製造方法によれば、上記したように、前鍛造工程で成形すべき中間鍛造品は、そのカップ状部の深さ寸法が比較的短寸のもので足りる。従って、前鍛造工程を冷間で実行することも可能となる。 In the above configuration, it is desirable that the ironing process is performed cold. This is because the molding accuracy of the final forged product can be increased, and this is advantageous in making it possible to manufacture a highly accurate outer joint member at low cost. Moreover, according to the manufacturing method which concerns on this invention, as above-mentioned, the intermediate forging goods which should be shape | molded by a pre-forging process should just have a comparatively short depth dimension of the cup-shaped part. Accordingly, it is possible to perform the pre-forging process cold.

　本発明は、しごき工程後のカップ状部の深さ寸法が３０～１５０ｍｍとされる最終鍛造品を得る際に好ましく適用することができる。 The present invention can be preferably applied when obtaining a final forged product in which the depth of the cup-shaped portion after the ironing step is 30 to 150 mm.

　本発明は、各トラック溝が直線状部分のみで構成された外側継手部材、例えばトリポード型等速自在継手（ＴＪ）やダブルオフセット型等速自在継手（ＤＯＪ）などに代表される摺動式等速自在継手の外側継手部材を製造する際に適用することができる。また、本発明は、各トラック溝が、直線状部分と円弧状部分とで構成された外側継手部材、例えばアンダーカットフリー型等速自在継手（ＵＪ）やバーフィールド型等速自在継手（ＢＪ）に代表される固定式等速自在継手の外側継手部材を製造する際に適用することもできる。 The present invention provides an outer joint member in which each track groove is composed only of a straight portion, for example, a sliding type represented by a tripod type constant velocity universal joint (TJ), a double offset type constant velocity universal joint (DOJ), and the like. It can be applied when manufacturing the outer joint member of the quick universal joint. The present invention also provides an outer joint member in which each track groove is composed of a linear portion and an arc-shaped portion, such as an undercut-free type constant velocity universal joint (UJ) or a barfield type constant velocity universal joint (BJ). It can also be applied when manufacturing an outer joint member of a fixed type constant velocity universal joint represented by.

　本発明は、カップ部の底部から軸方向に延びる軸部を一体に有する外側継手部材を製造する際にも好ましく適用することができる。 The present invention can be preferably applied also when manufacturing an outer joint member integrally having a shaft portion extending in the axial direction from the bottom portion of the cup portion.

　また、上記課題の解決は、外側継手部材に加工される本発明に係る中間鍛造品を次のような構成とすることで実現することができる。すなわち、本発明に係る外側継手部材の中間鍛造品は、一端が開口した有底筒状のカップ部を有し、カップ部の内径面に軸方向に延びる複数のトラック溝が設けられた等速自在継手用外側継手部材に加工されるものであって、内径面に軸方向に延びる複数のトラック溝が粗成形された有底筒状のカップ状部を有し、内周にパンチが挿入されたカップ状部と、その外径側に配置したダイスとをカップ状部の底部側から開口側に向けて圧入状態で相対移動させてカップ状部を塑性変形させることにより、仕上がり形状のトラック溝を有する最終鍛造品に成形されるものにおいて、カップ状部の外径面に、上記相対移動に伴うカップ状部の塑性変形代を徐々に増加させる方向の拡径面が設けられていることを特徴とする。 Moreover, the solution of the above problem can be realized by configuring the intermediate forged product according to the present invention to be processed into the outer joint member as follows. That is, the intermediate forged product of the outer joint member according to the present invention has a bottomed cylindrical cup portion with one end opened, and a constant velocity in which a plurality of track grooves extending in the axial direction are provided on the inner diameter surface of the cup portion. It is processed into an outer joint member for a universal joint, and has a bottomed cylindrical cup-shaped part in which a plurality of track grooves extending in the axial direction are formed on the inner diameter surface, and a punch is inserted into the inner periphery. The cup-shaped part and the die arranged on the outer diameter side thereof are moved relative to each other in the press-fitted state from the bottom side of the cup-shaped part toward the opening side, and the cup-shaped part is plastically deformed, thereby finishing the track groove. The outer diameter surface of the cup-shaped portion is provided with a diameter-expanded surface in a direction that gradually increases the plastic deformation allowance of the cup-shaped portion accompanying the relative movement. Features.

　この中間鍛造品において、上記の拡径面は、例えば、軸線に対する傾斜角が相互に異なる複数の面を軸方向に連続配置して構成されたものとすることができる。 In this intermediate forged product, the above-mentioned diameter-expanded surface can be constituted by, for example, continuously arranging a plurality of surfaces having different inclination angles with respect to the axis in the axial direction.

　以上に示すように、本発明によれば、所望の形状や強度を具備した外側継手部材を低コストに製造することが可能となる。これにより、等速自在継手の低コスト化に寄与することができる。 As described above, according to the present invention, an outer joint member having a desired shape and strength can be manufactured at low cost. Thereby, it can contribute to the cost reduction of a constant velocity universal joint.

本発明の実施形態に係る製造方法を用いて製造される外側継手部材の正面図である。It is a front view of the outside joint member manufactured using the manufacturing method concerning the embodiment of the present invention. 図１Ａ中に示すＸ１－Ｘ１線矢視概略断面図である。FIG. 1B is a schematic cross-sectional view taken along line X1-X1 shown in FIG. 1A. 前鍛造工程に投入される棒状素材の概略断面図である。It is a schematic sectional drawing of the rod-shaped raw material thrown into a pre forge process. 前鍛造工程の各鍛造ステップで得られる途中製品の概略断面図である。It is a schematic sectional drawing of the intermediate product obtained at each forge step of a pre-forging process. 前鍛造工程の各鍛造ステップで得られる途中製品の概略断面図である。It is a schematic sectional drawing of the intermediate product obtained at each forge step of a pre-forging process. 前鍛造工程の各鍛造ステップで得られる途中製品の概略断面図である。It is a schematic sectional drawing of the intermediate product obtained at each forge step of a pre-forging process. 中間鍛造品の概略正面図である。It is a schematic front view of an intermediate forging product. 図３Ａ中に示すＸ２－Ｘ２線矢視概略断面図である。FIG. 3B is a schematic cross-sectional view taken along line X2-X2 shown in FIG. 3A. 図３Ｂの要部拡大図である。It is a principal part enlarged view of FIG. 3B. 本発明に係る製造方法で採用する中間鍛造品と従来方法の中間鍛造品の形状を比較するための図である。It is a figure for comparing the shape of the intermediate forging product employ | adopted with the manufacturing method which concerns on this invention, and the intermediate forging product of the conventional method. しごき工程を模式的に示す部分断面図である。It is a fragmentary sectional view showing an ironing process typically. 他の実施形態に係る中間鍛造品の要部拡大断面図である。It is a principal part expanded sectional view of the intermediate forging product which concerns on other embodiment. 従来方法の問題点を模式的に示す図である。It is a figure which shows the problem of the conventional method typically.

　以下、本発明の実施の形態を図面に基づいて説明する。なお、以下では、便宜上、まず本発明に係る製造方法を用いて製造される外側継手部材の一例を説明し、続いて、本発明に係る外側継手部材の製造方法の実施形態を説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, for convenience, an example of an outer joint member manufactured using the manufacturing method according to the present invention will be described first, and then an embodiment of the method of manufacturing the outer joint member according to the present invention will be described.

　図１Ａに、等速自在継手用外側継手部材１（以下、単に「外側継手部材１」という）の概略正面図を示し、図１Ｂに同外側継手部材１の概略断面図（図１ＡのＸ１－Ｘ１線概略断面図）を示す。この外側継手部材１は、角度変位および軸方向変位の双方を許容する摺動式等速自在継手の一種であるトリポード型等速自在継手用の外側継手部材であって、筒部２ａおよび底部２ｂを一体に有する有底筒状のカップ部２と、カップ部２の底部２ｂから軸方向外方に延びた軸部３とを一体に備える。トリポード型等速自在継手は、この外側継手部材１のカップ部２の内周に、内側継手部材としてのトリポード部材やトルク伝達部材としてのローラなどを組み込むことで完成する。 FIG. 1A shows a schematic front view of an outer joint member 1 for a constant velocity universal joint (hereinafter simply referred to as “outer joint member 1”), and FIG. 1B shows a schematic sectional view of the outer joint member 1 (X1-X1 in FIG. 1A). X1 line schematic sectional drawing) is shown. This outer joint member 1 is an outer joint member for a tripod type constant velocity universal joint that is a kind of sliding type constant velocity universal joint that allows both angular displacement and axial displacement, and includes a cylindrical portion 2a and a bottom portion 2b. Are integrally provided with a bottomed cylindrical cup portion 2 and a shaft portion 3 extending axially outward from a bottom portion 2b of the cup portion 2. The tripod type constant velocity universal joint is completed by incorporating a tripod member as an inner joint member, a roller as a torque transmission member, or the like on the inner periphery of the cup portion 2 of the outer joint member 1.

　カップ部２（筒部２ａ）の内径面４には、軸方向に延びる３本のトラック溝５が等間隔で形成されている。各トラック溝５は、円周方向で対向する一対のローラ案内面６，６を有し、ローラ案内面６，６も含めて軸線と平行に延びた直線状に形成されている。図１Ａに示すように、本実施形態のカップ部２は、大径部と小径部とを周方向で交互に三つずつ配して構成される断面花冠状とされ、各大径部の内径面にトラック溝５が形成されている。カップ部２の開口部内周縁のトラック溝５，５間領域には、継手の角度変位を許容するため（図示しないトリポード部材から延びる軸がカップ部２と干渉するのを回避するため）の入口チャンファ７が設けられる。また、カップ部２の外径面には、継手内部を密封するブーツの一端部が嵌着される周方向溝８が設けられている。 Three track grooves 5 extending in the axial direction are formed at equal intervals on the inner diameter surface 4 of the cup portion 2 (cylinder portion 2a). Each track groove 5 has a pair of roller guide surfaces 6 and 6 that face each other in the circumferential direction, and is formed in a straight line including the roller guide surfaces 6 and 6 and extending parallel to the axis. As shown to FIG. 1A, the cup part 2 of this embodiment is made into the cross-sectional corollary shape comprised by arranging three large diameter parts and small diameter parts alternately in the circumferential direction, and the internal diameter of each large diameter part A track groove 5 is formed on the surface. In the region between the

track grooves

5 and 5 on the inner peripheral edge of the opening of the cup portion 2, an inlet chamfer for allowing angular displacement of the joint (in order to avoid a shaft extending from a tripod member not shown from interfering with the cup portion 2). 7 is provided. Moreover, the circumferential direction groove | channel 8 by which the one end part of the boot which seals the inside of a coupling is fitted is provided in the outer diameter surface of the cup part 2. As shown in FIG.

　以下、上述した外側継手部材１の製造方法の一例であって、本発明に係る製造方法の実施の形態を、図面を参照しながら詳細に説明する。大まかに言うと、上述した外側継手部材１は、図２Ａに示す棒状素材Ｍを図３Ａ，図３Ｂに示す中間鍛造品２１に成形する前鍛造工程、中間鍛造品２１を図６中に二点鎖線で示す最終鍛造品１１に成形するしごき工程、最終鍛造品１１の各部を完成品形状に仕上げる仕上げ工程、および完成品形状に仕上げられた最終鍛造品１１に熱処理を施す熱処理工程等を経て製造される。 Hereinafter, an embodiment of the manufacturing method according to the present invention, which is an example of the manufacturing method of the outer joint member 1 described above, will be described in detail with reference to the drawings. Roughly speaking, the outer joint member 1 described above includes a pre-forging step of forming the rod-shaped material M shown in FIG. 2A into the intermediate forged product 21 shown in FIGS. 3A and 3B, and the intermediate forged product 21 in two points in FIG. Manufactured through an ironing process for forming the final forged product 11 indicated by a chain line, a finishing process for finishing each part of the final forged product 11 into a finished product shape, and a heat treatment process for heat-treating the final forged product 11 finished in the finished product shape. Is done.

　前鍛造工程では、複数の鍛造ステップ（ここでは４つのステップ）を経ることにより、図２Ａに示す棒状素材Ｍを、図３Ａ，図３Ｂに示すカップ状部２２を有する中間鍛造品２１に成形する。 In the pre-forging process, a bar-shaped material M shown in FIG. 2A is formed into an intermediate forged product 21 having a cup-shaped portion 22 shown in FIGS. 3A and 3B by going through a plurality of forging steps (here, four steps). .

　具体的には、まず、第１の鍛造ステップにおいて、図２Ａに示す棒状素材Ｍに据え込み加工を施すことにより、棒状素材Ｍを、一端外周縁部が丸められた第１の途中製品Ｍ１（図２Ｂ参照）に成形する。次いで、第２の鍛造ステップにおいて、第１の途中製品Ｍ１に前方押し出し加工を施すことにより、第１の途中製品Ｍ１を、一端側に軸状部１３（最終的に軸部３に仕上げられる部位）を有する第２の途中製品Ｍ２（図２Ｃ参照）に成形する。次いで、第３の鍛造ステップにおいて、第２の途中製品Ｍ２に据え込み加工を施すことにより、第２の途中製品Ｍ２を、据え込み部Ｎおよび軸状部１３を一体に有する第３の途中製品Ｍ３（図２Ｄ参照）に成形する。そして、第４の鍛造ステップにおいて、第３の途中製品Ｍ３の据え込み部Ｎに対して後方押し出し加工を施すことにより、第３の途中製品Ｍ３を、カップ状部２２および軸状部１３を一体に有する中間鍛造品２１（図３Ａ，図３Ｂ参照）に成形する。 Specifically, first, in the first forging step, the rod-shaped material M shown in FIG. 2A is subjected to an upsetting process, whereby the rod-shaped material M is converted into a first intermediate product M1 (one outer peripheral edge of which is rounded). (See FIG. 2B). Next, in the second forging step, the first intermediate product M1 is subjected to a forward extrusion process, so that the first intermediate product M1 is formed on one end side with a shaft-like portion 13 (part finally finished to the shaft portion 3). ) Having a second intermediate product M2 (see FIG. 2C). Next, in the third forging step, by performing upsetting on the second intermediate product M2, the second intermediate product M2 and the third intermediate product integrally including the upsetting portion N and the shaft-like portion 13 are provided. Molded to M3 (see FIG. 2D). Then, in the fourth forging step, the third intermediate product M3 is integrated with the cup-shaped portion 22 and the shaft-shaped portion 13 by subjecting the upset portion N of the third intermediate product M3 to rearward extrusion. Is formed into an intermediate forged product 21 (see FIGS. 3A and 3B).

　この前鍛造工程は、各ワーク（棒状素材Ｍ及び途中製品Ｍ１～Ｍ３）を所定形状に成形し得る限りにおいて、冷間、温間、亜熱間又は熱間の何れの温度領域で実行しても良い。因みに、冷間鍛造とは、概ね２００℃以下とされたワークに対して鍛造加工を施す手法であり、温間鍛造とは、概ね６００～７００℃程度に加熱されたワークに対して鍛造加工を施す手法である。また、亜熱間鍛造とは、概ね７５０～１０００℃程度に加熱されたワークに対して鍛造加工を施す手法であり、熱間鍛造とは、概ね１０００～１２００℃程度に加熱されたワークに対して鍛造加工を施す手法である。なお、前鍛造工程で使用する金型寿命を延ばしつつ、高精度の中間鍛造品２１を安定的に得る観点から言えば、前鍛造工程は冷間で実行するのが好ましい。 This pre-forging process is performed in any temperature range between cold, warm, sub-hot, and hot as long as each workpiece (rod-like material M and intermediate products M1 to M3) can be formed into a predetermined shape. Also good. In this connection, cold forging is a technique for forging a workpiece that is approximately 200 ° C. or less, and warm forging is forging a workpiece heated to approximately 600 to 700 ° C. It is a technique to apply. Sub-hot forging is a technique for forging a workpiece heated to about 750 to 1000 ° C., and hot forging is about a workpiece heated to about 1000 to 1200 ° C. This is a technique for forging. From the viewpoint of stably obtaining the high-precision intermediate forged product 21 while extending the life of the mold used in the pre-forging process, it is preferable to perform the pre-forging process cold.

　以下、中間鍛造品２１の詳細構造を説明する。図３Ａ，図３Ｂに示すように、中間鍛造品２１のカップ状部２２は、筒部２２ａ及び底部２２ｂを一体に有する有底筒状をなし、その内径面（筒部２２ａの内径面）の周方向三等分位置には、ローラ案内面１６を有するトラック溝１５が粗成形されている。中間鍛造品２１のカップ状部２２は、後述するしごき工程において、筒部２２ａがダイス５１及びパンチ５２の成形面に倣って塑性変形することにより、内径面に仕上がり形状のトラック溝を有する（図１に示す外側継手部材１のカップ部２と横断面形状が同一の）カップ状部１２（図６中の二点鎖線を参照）に仕上げられる。そのため、筒部２２ａの周方向各部は、カップ部２の筒部２ａよりも厚肉とされ、また、カップ状部２２の深さ寸法（筒部２２ａの軸方向寸法）は、カップ部２の深さ寸法（筒部２ａの軸方向寸法）よりも短寸とされる。 Hereinafter, the detailed structure of the intermediate forged product 21 will be described. As shown in FIGS. 3A and 3B, the cup-shaped portion 22 of the intermediate forged product 21 has a bottomed cylindrical shape integrally including a cylindrical portion 22a and a bottom portion 22b, and has an inner diameter surface (an inner diameter surface of the cylindrical portion 22a). A track groove 15 having a roller guide surface 16 is roughly formed in the circumferentially divided position. The cup-shaped portion 22 of the intermediate forged product 21 has a track groove having a finished shape on the inner diameter surface by plastic deformation of the cylindrical portion 22a following the forming surface of the die 51 and the punch 52 in the ironing process described later (FIG. The cup-shaped portion 12 (see the two-dot chain line in FIG. 6) having the same cross-sectional shape as the cup portion 2 of the outer joint member 1 shown in FIG. Therefore, each part in the circumferential direction of the cylindrical part 22a is thicker than the cylindrical part 2a of the cup part 2, and the depth dimension of the cup-shaped part 22 (axial dimension of the cylindrical part 22a) is the same as that of the cup part 2. It is shorter than the depth dimension (the axial dimension of the cylinder portion 2a).

　カップ状部２２の内径面は、その軸方向全域が軸線と平行なストレート面に形成されている。一方、カップ状部２２の外径面２３は、その開口側領域が軸線と平行なストレート面に形成されているのに対し、その底部側領域が、底部側から開口側に向けて、筒部２２ａの外径寸法を徐々に拡大させる方向の拡径面に形成されている。かかる構成から、筒部２２ａの底部側領域の肉厚は、底部側から開口側に向けて徐々に増大している。本実施形態において、上記の拡径面２４は、軸線に対する傾斜角が相互に異なる複数の面を軸方向に連続配置して構成されている。ここでは、図４に拡大して示すように、相対的に開口側に位置し、軸線に対する傾斜角が相対的に小さいテーパ面状をなした第１拡径面２５と、相対的に底部側に位置し、軸線に対する傾斜角が相対的に大きいテーパ面状をなした第２拡径面２６とで拡径面２４が構成される。 The inner diameter surface of the cup-shaped part 22 is formed in a straight surface whose entire axial direction is parallel to the axis. On the other hand, the outer diameter surface 23 of the cup-shaped part 22 is formed in a straight surface whose opening side region is parallel to the axis, whereas the bottom side region is formed from the bottom side toward the opening side, and the cylindrical part The outer diameter of 22a is formed on the enlarged surface in the direction of gradually increasing the outer diameter. With this configuration, the thickness of the bottom side region of the cylindrical portion 22a gradually increases from the bottom side toward the opening side. In the present embodiment, the above-described enlarged diameter surface 24 is configured by continuously arranging a plurality of surfaces having different inclination angles with respect to the axis in the axial direction. Here, as shown in an enlarged view in FIG. 4, the first enlarged surface 25 which is located on the relatively opening side and has a tapered surface shape with a relatively small inclination angle with respect to the axis, and the bottom side relatively. The diameter-expanded surface 24 is constituted by the second diameter-expanded surface 26 that is located at a position where the taper surface has a relatively large inclination angle with respect to the axis.

　拡径面２４は、その最小径部（第２拡径面２６の底側端部）が、カップ状部２２の外底面２２ｂ２の外径端部Ａ（厳密には、Ｒ部を設けない場合の外径端部。以下、これを「Ａ点」ともいう）に配置されると共に、その最大径部（第１拡径面２５の開口側端部）が、カップ状部２２の外径面２３の軸方向略中央部Ｃ（以下、これを「Ｃ点」という）に配置されるようにして、カップ状部２２の外径面２３に設けられている。さらに、第２拡径面２６は、その開口側端部Ｂ（第１拡径面２５と第２拡径面２６の接続部。以下、これを「Ｂ点」という）が、カップ状部２２の外径面２３のうち、筒部２２ａの基端部に配置されるようにして、カップ状部２２の外径面２３に設けられている。 The diameter-expanded surface 24 has a minimum diameter portion (bottom side end portion of the second diameter-expanded surface 26), and the outer-diameter end portion A (strictly speaking, the R portion is not provided) of the outer bottom surface 22b2 of the cup-shaped portion 22. The outer diameter end portion of the cup-shaped portion 22 is arranged at the outer diameter end portion of the cup-shaped portion 22 (hereinafter also referred to as “point A”). It is provided on the outer diameter surface 23 of the cup-shaped portion 22 so as to be disposed at a substantially central portion C in the axial direction of 23 (hereinafter referred to as “C point”). Further, the second enlarged surface 26 has an opening-side end B (a connecting portion between the first enlarged surface 25 and the second enlarged surface 26, hereinafter referred to as “point B”). The outer diameter surface 23 is provided on the outer diameter surface 23 of the cup-shaped portion 22 so as to be disposed at the proximal end portion of the cylindrical portion 22a.

　本実施形態において、カップ状部２２のうち、Ａ点における直径寸法ｄ１［単位：ｍｍ］は、Ａ点が後述するしごき工程で使用するダイス５１の成形面５１ａ（図６参照）に対して０ｍｍよりも大きく２ｍｍ以下の塑性変形代をもって圧入される値に設定されている。つまり、ダイス５１の成形面５１ａのうち、Ａ点が圧入される部分の直径寸法をＤ１［ｍｍ］としたとき、Ｄ１＜ｄ１≦Ｄ１＋２［ｍｍ］の関係式が成立するように、Ａ点の直径寸法ｄ１が設定される。なお、上記の関係式を、具体的な寸法値を含まない関係式として規定するならば、カップ状部２２のうちＡ点を含む部分のしごき加工前における肉厚をＸａ、当該部分のしごき加工後における肉厚をＸｂとしたとき、Ｘｂ≧０．９Ｘａ（厳密には、Ｘａ＞Ｘｂ≧０．９Ｘａ）とすることができる。換言すると、中間鍛造品２１のうち、カップ状部２２のＡ点を含む部分の肉厚は、しごき加工に伴って１０％以下減少するように、その値が規定されている。 In this embodiment, the diameter dimension d1 [unit: mm] at the point A in the cup-shaped portion 22 is 0 mm with respect to the molding surface 51a (see FIG. 6) of the die 51 that the point A uses in the ironing process described later. It is set to a value that is press-fitted with a plastic deformation allowance of 2 mm or less. That is, of the molding surface 51a of the die 51, when the diameter dimension of the portion into which the point A is press-fitted is D1 [mm], the relational expression of D1 <d1 ≦ D1 + 2 [mm] is satisfied. A diameter dimension d1 is set. If the above relational expression is defined as a relational expression not including a specific dimension value, the thickness of the portion including the point A in the cup-shaped portion 22 before the ironing processing is Xa, and the ironing processing of the portion is performed. When the subsequent thickness is Xb, Xb ≧ 0.9Xa (strictly, Xa> Xb ≧ 0.9Xa) can be satisfied. In other words, the value of the thickness of the portion including the point A of the cup-shaped portion 22 in the intermediate forged product 21 is defined so as to decrease by 10% or less with ironing.

　そして、上記のとおり、Ａ点は拡径面２４の最小径部であることから、Ｂ点では、しごき加工に伴うカップ状部２２の塑性変形代がＡ点よりも大きくなり、さらに、Ｃ点では、しごき加工に伴うカップ状部２２の塑性変形代がＢ点よりも大きくなる。ここでは、筒部２２ａのうち、Ｂ点を含んだ基端部の肉厚ｔｂ（図４参照）が、しごき加工後に１５％以上３０％以下減少する値に設定され、Ｃ点を含んだ軸方向中央部の肉厚ｔｃ（図３Ｂ参照）が、しごき加工後に筒部２２ａの基端部よりも大きく、かつ１５％以上６０％以下減少する値に設定されている。 As described above, since the point A is the minimum diameter portion of the expanded surface 24, the plastic deformation allowance of the cup-shaped portion 22 accompanying the ironing process is larger than the point A at the point B, and further the point C. Then, the plastic deformation allowance of the cup-shaped part 22 accompanying ironing becomes larger than B point. Here, the thickness tb (see FIG. 4) of the base end portion including the B point in the cylindrical portion 22a is set to a value that decreases by 15% or more and 30% or less after the ironing process, and the shaft including the C point. The thickness tc (see FIG. 3B) at the center in the direction is set to a value that is larger than the base end portion of the cylindrical portion 22a after ironing and decreases by 15% or more and 60% or less.

　以上の構成を有する中間鍛造品２１はしごき工程に移送される。しごき工程では、図６に示すように、同軸配置されたダイス５１及びパンチ５２を用いて中間鍛造品２１に冷間でしごき加工を施すことにより、中間鍛造品２１（のカップ状部２２）を、同図中二点鎖線で示すカップ状部２１を有する最終鍛造品１１に成形する。詳細な図示は省略するが、ダイス５１の内径面には、軸線に沿って延び、カップ部２外周の横断面形状に対応した成形面（しごき面）５１ａが設けられ、また、パンチ５２の外径面には、カップ部２内周の横断面形状に対応した成形面が設けられている。 The intermediate forged product 21 having the above configuration is transferred to the ironing process. In the ironing process, as shown in FIG. 6, the intermediate forged product 21 (the cup-shaped portion 22 thereof) is formed by subjecting the intermediate forged product 21 to a cold ironing process using a coaxially disposed die 51 and a punch 52. The final forged product 11 having a cup-shaped portion 21 indicated by a two-dot chain line in FIG. Although detailed illustration is omitted, the inner surface of the die 51 is provided with a molding surface (ironing surface) 51 a that extends along the axis and corresponds to the cross-sectional shape of the outer periphery of the cup portion 2. The radial surface is provided with a molding surface corresponding to the cross-sectional shape of the inner periphery of the cup portion 2.

　しごき加工は、中間鍛造品２１のカップ状部２２の内周にパンチ５２を挿入した状態で、ダイス５１をカップ状部２２の底部側から開口側に向けて圧入状態で相対移動させることにより行われる。本実施形態では、カップ状部２２及びダイス５１の成形面５１ａが上記の形状を具備していることにより、しごき加工は、ダイス５１に対するカップ状部２２の圧入代（カップ状部２２の塑性変形量）が徐々に増大するかたちで進行する。そして、しごき加工が進行するのに伴って、カップ状部２２（の筒部２２ａ）は、ダイス５１の成形面５１ａおよびパンチ５２の成形面に倣いながら軸方向に徐々に伸長変形し、しごき加工が完了すると、内径面に仕上がり形状のトラック溝が設けられたカップ状部１２を有する最終鍛造品１１（図６中の二点鎖線参照）が得られる。なお、最終鍛造品１１のカップ深さは、外側継手部材１を構成部品とする等速自在継手の用途等（車種等）によって異なるが、概ね３０ｍｍ～１５０ｍｍの範囲内とされる。 Ironing is performed by relatively moving the die 51 in a press-fit state from the bottom side of the cup-shaped portion 22 toward the opening side with the punch 52 inserted in the inner periphery of the cup-shaped portion 22 of the intermediate forged product 21. Is called. In the present embodiment, since the molding surface 51a of the cup-shaped portion 22 and the die 51 has the above-described shape, the ironing process is performed by pressing the cup-shaped portion 22 into the die 51 (plastic deformation of the cup-shaped portion 22). It progresses in such a way that the amount increases gradually. As the ironing process proceeds, the cup-shaped part 22 (the cylindrical part 22a) gradually expands and deforms in the axial direction while following the molding surface 51a of the die 51 and the molding surface of the punch 52, and the ironing process is performed. Is completed, a final forged product 11 (see a two-dot chain line in FIG. 6) having a cup-shaped portion 12 having a finished track groove on the inner diameter surface is obtained. The cup depth of the final forged product 11 varies depending on the use of the constant velocity universal joint having the outer joint member 1 as a component (vehicle type, etc.), but is generally in the range of 30 mm to 150 mm.

　しごき工程で得られた最終鍛造品２１は、仕上げ工程に移送される。仕上げ工程では、以上で述べた鍛造加工では成形することが難しい部位（例えば、カップ部２の外径面に設けるべき周方向溝８や、軸部３の自由端外径に設けるべきスプライン等）を形成するための加工の他、カップ状部１２の開口端面を平坦面に仕上げるための旋削加工が最終鍛造品１１に適宜施され、最終鍛造品１１の全体が完成品形状に仕上げられる。そして、全体が完成品形状に仕上げられた最終鍛造品１１に焼入れ等の熱処理を施すことにより、図１に示す外側継手部材１が完成する。 The final forged product 21 obtained in the ironing process is transferred to the finishing process. In the finishing process, it is difficult to form by the forging process described above (for example, the circumferential groove 8 to be provided on the outer diameter surface of the cup portion 2 or the spline to be provided on the outer diameter of the free end of the shaft portion 3). In addition to the process for forming the end forged product 11, a turning process for finishing the open end surface of the cup-shaped portion 12 to a flat surface is appropriately applied to the final forged product 11, and the entire final forged product 11 is finished into a finished product shape. And the outer joint member 1 shown in FIG. 1 is completed by performing heat processing, such as quenching, on the final forged product 11 which has been finished into a finished product shape as a whole.

　上記したように、しごき工程で使用するダイス５１の内径面に設けられる成形面５１ａの横断面形状は、外側継手部材１を構成するカップ部２外周の横断面形状に対応している。このため、ダイス５１の成形面５１ａ形状に変更を加えると、カップ部２の外周形状、ひいては外側継手部材１の機能・性能に影響を及ぼすおそれがあることから好ましくない。そこで、本発明では、前鍛造工程において、その後のしごき工程でダイス５１とカップ状部２２の圧入状態での相対移動（しごき加工）が進行するのに伴って、カップ状部２２の塑性変形代を徐々に増加させる方向の拡径面２４がカップ状部２２の外径面２３に設けられた中間鍛造品２１を成形するようにした。より具体的には、中間鍛造品２１を、カップ状部２２の外底面２２ｂ１の外径端Ａ（Ａ点）に拡径面２４の最小径部が配置され、かつ、しごき加工に伴う外径端Ａを含む部分の肉厚減少率が１０％以下となるようにダイス５１に圧入されるものとした（本実施形態では、上記の外径端Ａが２ｍｍ以下の塑性変形代をもってダイス５１に圧入されるものとした）。 As described above, the cross-sectional shape of the molding surface 51a provided on the inner diameter surface of the die 51 used in the ironing process corresponds to the cross-sectional shape of the outer periphery of the cup portion 2 constituting the outer joint member 1. For this reason, if the shape of the molding surface 51 a of the die 51 is changed, it is not preferable because it may affect the outer peripheral shape of the cup portion 2 and consequently the function and performance of the outer joint member 1. Therefore, in the present invention, in the pre-forging process, as the relative movement (scoring processing) in the press-fitted state of the die 51 and the cup-shaped part 22 proceeds in the subsequent ironing process, the plastic deformation allowance of the cup-shaped part 22 is increased. The intermediate forged product 21 in which the diameter-expanded surface 24 in the direction of gradually increasing the diameter is provided on the outer-diameter surface 23 of the cup-shaped portion 22 is formed. More specifically, the intermediate forged product 21 is configured such that the minimum diameter portion of the expanded surface 24 is disposed at the outer diameter end A (point A) of the outer bottom surface 22b1 of the cup-shaped portion 22, and the outer diameter associated with the ironing process. It is assumed that the thickness reduction rate of the portion including the end A is press-fitted into the die 51 so as to be 10% or less (in the present embodiment, the outer diameter end A has a plastic deformation allowance of 2 mm or less to the die 51. To be press-fitted).

　このようにすれば、しごき加工の初期段階におけるダイス５１に対するカップ状部２２の圧入代、すなわちカップ状部２２の塑性変形量（しごき加工量）を少なくすることができる。これにより、しごき加工を実行するのに伴って、カップ状部２２を構成する筒部２２ａの基端部付近に応力集中が生じてカップ状部２２に亀裂が形成されるのを、また、カップ状部２２の底部２２ｂが大きく変形するのを可及的に防止することが可能となり、歩留の向上及び仕上げ加工の簡略化を通じて外側継手部材１の製造コストを低廉化することができる。さらに、中間鍛造品２１のうち、しごき加工の実質的な開始点であるカップ状部２２の外底面２２ｂ１の外径端Ａの塑性変形代を２ｍｍ以下とすれば（外径端Ａを含む部分の肉厚減少率δが１０％以下となるようにしごき加工を実行すれば）、ダイス５１に対する負担が効果的に軽減されるので、ダイス５１の長寿命化を図ることができる。 In this way, it is possible to reduce the press-fitting allowance of the cup-shaped portion 22 to the die 51 in the initial stage of ironing, that is, the amount of plastic deformation (the amount of ironing) of the cup-shaped portion 22. As a result, as the ironing process is performed, stress concentration occurs in the vicinity of the base end portion of the cylindrical portion 22a constituting the cup-shaped portion 22, and cracks are formed in the cup-shaped portion 22. It is possible to prevent the bottom portion 22b of the shape portion 22 from being greatly deformed as much as possible, and the manufacturing cost of the outer joint member 1 can be reduced through improvement in yield and simplification of finishing. Further, in the intermediate forged product 21, if the plastic deformation allowance of the outer diameter end A of the outer bottom surface 22b1 of the cup-shaped portion 22 which is a substantial starting point of the ironing process is 2 mm or less (the portion including the outer diameter end A) If the ironing process is performed so that the thickness reduction rate δ of the die is 10% or less), the burden on the die 51 is effectively reduced, so that the life of the die 51 can be extended.

　特に、本実施形態のように、中間鍛造品２１を、カップ状部２２を構成する筒部２２ａの基端部における肉厚ｔｂが、しごき工程後に１５％以上３５％以下減少するように、また、筒部２２ａの軸方向中央部の肉厚ｔｃが、しごき工程後に上記基端部よりも大きく、かつ１５％以上６０％以下減少するように、拡径面２４が設けられたものとすれば、しごき加工に伴って、カップ状部２２の筒部２２ａに亀裂が形成されたり、カップ状部２２の底部２２ｂが大きく変形したりするような事態を効果的に防止しつつ、所望のトラック溝長さ（カップ深さ）や機械的強度を有する最終鍛造品２１を得ることができる。 In particular, as in the present embodiment, the intermediate forged product 21 is formed so that the wall thickness tb at the base end portion of the cylindrical portion 22a constituting the cup-shaped portion 22 is reduced by 15% or more and 35% or less after the ironing process. If the diameter expansion surface 24 is provided such that the wall thickness tc of the central portion in the axial direction of the cylindrical portion 22a is larger than the base end portion and reduced by 15% or more and 60% or less after the ironing step. The desired track groove is effectively prevented while cracking is formed in the cylindrical portion 22a of the cup-shaped portion 22 or the bottom portion 22b of the cup-shaped portion 22 is greatly deformed due to the ironing process. A final forged product 21 having a length (cup depth) and mechanical strength can be obtained.

　なお、筒部２２ａの基端部および軸方向中央部の肉厚ｔｂ，ｔｃがしごき加工後に１５％以上減少するように（肉厚ｔｂ，ｔｃの肉厚減少率δが１５％以上となるように）カップ状部２２の外径面２３に拡径面２４を設けるようにしたのは、両部の肉厚減少率δが１５％を下回ると所望のトラック溝長さ等を得ることができない可能性が高まるからである。また、筒部２２ａの基端部の肉厚ｔｂがしごき加工に伴って４５％程度減少すると、カップ状部２２（筒部２２ａ）に亀裂が形成される可能性が格段に高まることから、拡径面２４は、安全率を考慮して、筒部２２ａの基端部の肉厚ｔｂがしごき加工に伴って３５％以下減少するようにカップ状部２２の外径面２３に設けるのが望ましい。また、筒部２２ａの軸方向中央部の肉厚ｔｃがしごき加工に伴って６５％程度減少する（しごき加工に伴う筒部２２ａの軸方向中央部の肉厚減少率δが６５％程度になる）と、カップ状部２２の筒部２２ａに亀裂が形成される可能性が格段に高まる。そのため、拡径面２４は、安全率を考慮して、筒部２２ａの軸方向中央部の肉厚ｔｃがしごき加工に伴って６０％以下減少するように（筒部２２ａの軸方向中央部のしごき加工に伴う肉厚減少率δが６０％以下となるように）カップ状部２２の外径面２３に設けるのが望ましい。 It should be noted that the thicknesses tb and tc of the base end portion and the axially central portion of the cylindrical portion 22a are reduced by 15% or more after the ironing process (the thickness reduction rate δ of the thicknesses tb and tc is 15% or more). (Ii) The increased diameter surface 24 is provided on the outer diameter surface 23 of the cup-shaped portion 22 because the desired track groove length or the like cannot be obtained if the thickness reduction rate δ of both portions is less than 15%. This is because the possibility increases. Further, if the thickness tb of the base end portion of the cylindrical portion 22a is reduced by about 45% due to the ironing process, the possibility that a crack is formed in the cup-shaped portion 22 (cylindrical portion 22a) is remarkably increased. In consideration of the safety factor, the radial surface 24 is preferably provided on the outer diameter surface 23 of the cup-shaped portion 22 so that the thickness tb of the base end portion of the cylindrical portion 22a is reduced by 35% or less with ironing. . Further, the thickness tc of the central portion in the axial direction of the cylindrical portion 22a is reduced by about 65% with the ironing process (the thickness reduction rate δ at the central portion in the axial direction of the cylindrical portion 22a with the ironing processing is about 65%. ) And the possibility that a crack is formed in the cylindrical portion 22a of the cup-shaped portion 22 is remarkably increased. Therefore, in consideration of the safety factor, the diameter-expanded surface 24 is formed so that the thickness tc of the central portion in the axial direction of the cylindrical portion 22a is reduced by 60% or less (corresponding to the central portion in the axial direction of the cylindrical portion 22a). It is desirable to provide it on the outer diameter surface 23 of the cup-shaped portion 22 so that the thickness reduction rate δ accompanying the ironing process is 60% or less.

　そして、しごき加工に伴って、カップ状部２２（１２）に亀裂が形成されたり、カップ状部２２の底部２２ｂが大きく変形したりする事態を可及的に防止する事態が可及的に防止されれば、筒部２２ａの肉厚減少率が全体として高まるように、すなわち、所望のトラック溝長さや加工硬化（機械的強度）を確保し得るように、中間鍛造品２１にしごき加工を施すことが可能となる。このように、筒部２２ａの肉厚減少率が高まるように中間鍛造品２１にしごき加工を施すことができれば、前鍛造工程で成形する中間鍛造品２１は、そのカップ深さが短寸のもので足りる。実際のところ、本発明に係る製造方法を採用すれば、図５に示すように、カップ深さが従来よりも短寸の中間鍛造品２１を成形することが可能となる。この場合、前鍛造工程で使用する鍛造金型（本実施形態では、特に第４の鍛造ステップで使用する後方押し出し用の鍛造金型）に対する負荷を軽減することが可能となり、当該鍛造金型の長寿命化を通じて、外側継手部材１の製造コストを低廉化することもできる。 In addition, it is possible to prevent as much as possible the situation in which a crack is formed in the cup-shaped portion 22 (12) or the bottom portion 22b of the cup-shaped portion 22 is greatly deformed due to the ironing process. Then, the intermediate forging 21 is subjected to ironing so that the thickness reduction rate of the cylindrical portion 22a is increased as a whole, that is, the desired track groove length and work hardening (mechanical strength) can be ensured. It becomes possible. Thus, if the intermediate forged product 21 can be ironed so as to increase the thickness reduction rate of the cylindrical portion 22a, the intermediate forged product 21 formed in the pre-forging process has a short cup depth. Is enough. Actually, if the manufacturing method according to the present invention is adopted, as shown in FIG. 5, it becomes possible to form an intermediate forged product 21 having a cup depth shorter than that of the conventional one. In this case, it becomes possible to reduce the load on the forging die used in the pre-forging step (in this embodiment, the forging die for backward extrusion used particularly in the fourth forging step). Through extending the service life, the manufacturing cost of the outer joint member 1 can be reduced.

　以上、本発明の一実施形態に係る外側継手部材１の製造方法について説明を行ったが、本発明は、上記の実施形態に限定適用されるものではなく、その要旨を逸脱しない範囲で種々の変更を加えることが可能である。 As mentioned above, although the manufacturing method of the outer joint member 1 which concerns on one Embodiment of this invention was demonstrated, this invention is not limitedly applied to said embodiment, Various in the range which does not deviate from the summary. It is possible to make changes.

　例えば、中間鍛造品２１のカップ状部２２の外径面２３に設けるべき拡径面２４のうち、第２拡径面２６は、上述したようなテーパ面状ではなく、図７に示すような円弧面状に形成することもできる。また、拡径面２４は、必ずしも、軸方向に連続配置した複数の面（以上で述べた実施形態では第１拡径面２５と第２拡径面２６）で構成する必要はなく、単一のテーパ面や円弧面で構成することもできる。要するに、拡径面２４は、カップ状部２２の筒部２２ａの基端部の肉厚ｔｂがしごき工程後に１５％以上３５％以下減少するように、より望ましくは、さらに筒部２２ａの軸方向中央部の肉厚ｔｃがしごき工程後に１５％以上６０％以下減少するように形成されていれば、どのような形態であっても問題なく採用することができる。 For example, among the enlarged diameter surfaces 24 to be provided on the outer diameter surface 23 of the cup-shaped portion 22 of the intermediate forged product 21, the second enlarged diameter surface 26 is not tapered as described above, but as shown in FIG. It can also be formed in a circular arc shape. Further, the diameter-expanded surface 24 is not necessarily configured by a plurality of surfaces continuously arranged in the axial direction (in the embodiment described above, the first diameter-expanded surface 25 and the second diameter-expanded surface 26). It can also be constituted by a tapered surface or an arc surface. In short, the diameter-expanded surface 24 is more preferably further in the axial direction of the cylindrical portion 22a so that the thickness tb of the base end portion of the cylindrical portion 22a of the cup-shaped portion 22 is reduced by 15% or more and 35% or less after the ironing process. As long as the thickness tc of the central portion is formed so as to decrease by 15% or more and 60% or less after the ironing process, any form can be adopted without any problem.

　また、以上では、前鍛造工程を４つの鍛造ステップで構成した場合（中間鍛造品２１を４つの鍛造ステップを経て得る場合）に本発明を適用したが、中間鍛造品２１を３以下又は５以上の鍛造ステップを得て得る場合にも本発明は好ましく適用し得る。 In the above, the present invention is applied when the pre-forging process is configured by four forging steps (when the intermediate forged product 21 is obtained through four forging steps), but the intermediate forged product 21 is 3 or less or 5 or more. The present invention can be preferably applied also when the forging step is obtained.

　また、以上では、摺動式等速自在継手の一種であるトリポード型等速自在継手（ＴＪ）用の外側継手部材１を製造する際に本発明を適用したが、本発明は、ダブルオフセット型等速自在継手（ＤＯＪ）等、その他の摺動式等速自在継手の外側継手部材を製造する際にも好ましく適用することができる。 In the above, the present invention is applied when manufacturing the outer joint member 1 for a tripod type constant velocity universal joint (TJ) which is a kind of sliding type constant velocity universal joint. However, the present invention is a double offset type. The invention can also be preferably applied to the production of outer joint members of other sliding constant velocity universal joints such as constant velocity universal joints (DOJ).

　さらに、本発明は、角度変位及び軸方向変位の双方を許容する摺動式等速自在継手の外側継手部材のみならず、角度変位のみを許容する固定式等速自在継手、例えばバーフィールド型等速自在継手（ＢＪ）やアンダーカットフリー型等速自在継手（ＵＪ）の外側継手部材を製造する際にも適用し得る。固定式等速自在継手の外側継手部材では、そのカップ部の内径面に設けられる各トラック溝が、直線状部分と円弧状部分とで構成される。 Furthermore, the present invention provides not only an outer joint member of a sliding type constant velocity universal joint that allows both angular displacement and axial displacement, but also a fixed type constant velocity universal joint that allows only angular displacement, such as a barfield type. The present invention can also be applied when manufacturing an outer joint member of a speed universal joint (BJ) or an undercut free type constant speed universal joint (UJ). In the outer joint member of the fixed type constant velocity universal joint, each track groove provided on the inner diameter surface of the cup portion includes a linear portion and an arc-shaped portion.

　１　　　外側継手部材
　２　　　カップ部
　３　　　軸部
　５　　　トラック溝
　６　　　案内面
　１１　　最終鍛造品
　１２　　カップ状部
　２１　　中間鍛造品
　２２　　カップ状部
　２３　　外径面
　２４　　拡径面
　２５　　第１拡径面
　２６　　第２拡径面
　５１　　ダイス
　５１ａ　成形面
　５２　　パンチ
　Ａ　　　カップ状部の外底面の外径端部
　Ｍ　　　棒状素材
　ｔｂ　　筒部の基端部の肉厚
　ｔｃ　　筒部の軸方向中央部の肉厚 DESCRIPTION OF SYMBOLS 1 Outer joint member 2 Cup part 3 Shaft part 5 Track groove 6 Guide surface 11 Final forged product 12 Cup-shaped part 21 Intermediate forged product 22 Cup-shaped part 23 Outer diameter surface 24 Expanded surface 25 First expanded surface 26 Second expanded surface Diameter 51 Die 51a Molding surface 52 Punch A Outer end of the outer bottom of the cup-shaped part M Bar material tb Thickness of the base end of the cylindrical part tc Thickness of the axially central part of the cylindrical part

Claims

　一端が開口した有底筒状のカップ部を有し、カップ部の内径面に軸方向に延びる複数のトラック溝が設けられた等速自在継手用外側継手部材の製造方法であって、
　棒状素材を、内径面にトラック溝が粗成形された有底筒状のカップ状部を有する中間鍛造品に成形する前鍛造工程と、
　内周にパンチが挿入された中間鍛造品の前記カップ状部に対し、その外径側に配置したダイスを前記カップ状部の底部側から開口側に向けて圧入状態で相対移動させて前記カップ状部を塑性変形させることにより、中間鍛造品を、仕上がり形状のトラック溝を有する最終鍛造品に成形するしごき工程と、を含み、
　前鍛造工程では、その後のしごき工程で前記相対移動が進行するのに伴って、前記カップ状部の塑性変形代を徐々に増加させる方向の拡径面が前記カップ状部の外径面に設けられた中間鍛造品を成形することを特徴とする等速自在継手用外側継手部材の製造方法。 A method of manufacturing an outer joint member for a constant velocity universal joint having a bottomed cylindrical cup portion having one end opened, and having a plurality of track grooves extending in an axial direction on an inner diameter surface of the cup portion,
A pre-forging step of forming a rod-shaped material into an intermediate forged product having a bottomed cylindrical cup-shaped portion having a track groove roughly formed on an inner diameter surface;
With respect to the cup-shaped portion of the intermediate forged product in which a punch is inserted on the inner periphery, a die disposed on the outer diameter side thereof is relatively moved in a press-fit state from the bottom side of the cup-shaped portion toward the opening side, thereby the cup. An intermediate forging product is formed into a final forging product having track grooves of a finished shape by plastically deforming the shape portion,
In the pre-forging step, as the relative movement proceeds in the subsequent ironing step, a diameter-expanding surface in a direction that gradually increases the plastic deformation allowance of the cup-shaped portion is provided on the outer diameter surface of the cup-shaped portion. A method for producing an outer joint member for a constant velocity universal joint, wherein the intermediate forged product is formed.
　中間鍛造品を、前記カップ状部の外底面の外径端に前記拡径面の最小径部が配置されたものとすることを特徴とする請求項１に記載の等速自在継手用外側継手部材の製造方法。 The outer joint for a constant velocity universal joint according to claim 1, wherein the intermediate forged product is configured such that a minimum diameter portion of the enlarged diameter surface is disposed at an outer diameter end of an outer bottom surface of the cup-shaped portion. Manufacturing method of member.
　中間鍛造品を、前記カップ状部を構成する筒部の基端部における肉厚が、しごき工程後に１５％以上３５％以下減少するように前記拡径面が設けられたものとすることを特徴とする請求項１又は２に記載の等速自在継手用外側継手部材の製造方法。 The intermediate forged product is characterized in that the diameter-expanded surface is provided so that the thickness at the base end portion of the cylindrical portion constituting the cup-shaped portion is reduced by 15% or more and 35% or less after the ironing step. The manufacturing method of the outer joint member for constant velocity universal joints of Claim 1 or 2.
　中間鍛造品を、前記筒部の軸方向中央部の肉厚が、しごき工程後に前記基端部よりも大きく減少するように前記拡径面が設けられたものとすることを特徴とする請求項３に記載の等速自在継手用外側継手部材の製造方法。 The intermediate forging product is characterized in that the diameter-expanded surface is provided so that the thickness of the central portion in the axial direction of the cylindrical portion is reduced more than the base end portion after the ironing step. 4. A method for producing an outer joint member for a constant velocity universal joint according to claim 3.
　中間鍛造品を、前記筒部の軸方向中央部の肉厚が、しごき工程後に１５％以上６０％以下減少するように前記拡径面が設けられたものとすることを特徴とする請求項４に記載の等速自在継手用外側継手部材の製造方法。 The intermediate forging product is characterized in that the diameter-expanded surface is provided so that the thickness of the central portion in the axial direction of the cylindrical portion is reduced by 15% or more and 60% or less after the ironing step. The manufacturing method of the outer joint member for constant velocity universal joints of description.
　中間鍛造品を、前記カップ状部の外径面の軸方向中央部に前記拡径面の最大径部が配置されたものとすることを特徴とする請求項１～５の何れか一項に記載の等速自在継手用外側継手部材の製造方法。 The intermediate forged product according to any one of claims 1 to 5, wherein a maximum diameter portion of the expanded surface is arranged in an axial central portion of an outer diameter surface of the cup-shaped portion. The manufacturing method of the outer joint member for constant velocity universal joints of description.
　しごき工程を冷間で実行することを特徴とする請求項１～６の何れか一項に記載の等速自在継手用外側継手部材の製造方法。 The method for manufacturing an outer joint member for a constant velocity universal joint according to any one of claims 1 to 6, wherein the ironing step is performed cold.
　トラック溝が、直線状部分のみで構成されるものに適用する請求項１～７の何れか一項に記載の等速自在継手用外側継手部材の製造方法。 The method for manufacturing an outer joint member for a constant velocity universal joint according to any one of claims 1 to 7, wherein the track groove is applied only to a linear portion.
　トラック溝が、直線状部分と円弧状部分とで構成されるものに適用する請求項１～７の何れか一項に記載の等速自在継手用外側継手部材の製造方法。 The method for manufacturing an outer joint member for a constant velocity universal joint according to any one of claims 1 to 7, wherein the track groove is applied to a groove formed of a linear portion and an arc-shaped portion.
　一端が開口した有底筒状のカップ部を有し、カップ部の内径面に軸方向に延びる複数のトラック溝が設けられた等速自在継手用外側継手部材に加工される中間鍛造品であって、内径面に軸方向に延びる複数のトラック溝が粗成形された有底筒状のカップ状部を有し、内周にパンチが挿入された前記カップ状部と、その外径側に配置したダイスとを前記カップ状部の底部側から開口側に向けて圧入状態で相対移動させて前記カップ状部を塑性変形させることにより、仕上がり形状のトラック溝を有する最終鍛造品に成形されるものにおいて、
　前記カップ状部の外径面に、前記相対移動に伴う前記カップ状部の塑性変形代を徐々に増加させる方向の拡径面が設けられていることを特徴とする中間鍛造品。 It is an intermediate forged product that is machined into an outer joint member for a constant velocity universal joint that has a bottomed cylindrical cup portion that is open at one end, and is provided with a plurality of track grooves extending in the axial direction on the inner diameter surface of the cup portion. A cup-shaped portion having a bottomed cylindrical shape in which a plurality of track grooves extending in the axial direction on the inner diameter surface are roughly formed, and arranged on the outer diameter side of the cup-shaped portion in which a punch is inserted in the inner periphery The molded die is molded into a final forged product having a finished track groove by plastically deforming the cup-shaped portion by relatively moving the die from the bottom side of the cup-shaped portion toward the opening side. In
An intermediate forged product characterized in that an outer diameter surface of the cup-shaped portion is provided with a diameter-expanded surface in a direction that gradually increases a plastic deformation allowance of the cup-shaped portion accompanying the relative movement.
　前記拡径面は、軸線に対する傾斜角が相互に異なる複数の面を軸方向に連続配置して構成されたものであることを特徴とする請求項１０に記載の中間鍛造品。 11. The intermediate forged product according to claim 10, wherein the diameter-expanded surface is configured by continuously arranging a plurality of surfaces having different inclination angles with respect to the axis in the axial direction.