JP5012529B2

JP5012529B2 - Method for manufacturing raceway member for rolling device

Info

Publication number: JP5012529B2
Application number: JP2008010023A
Authority: JP
Inventors: 孝範宮坂; 泰之武藤
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2008-01-21
Filing date: 2008-01-21
Publication date: 2012-08-29
Anticipated expiration: 2028-01-21
Also published as: JP2009168229A

Description

この発明は転動装置（転がり軸受、転がり軸受ユニット、ボールねじ装置、リニアガイド装置等）を構成する軌道部材（転がり軸受の外輪及び内輪、転がり軸受ユニットの外径側軌道輪部材及び内径側軌道輪部材、ボールねじ装置のねじ軸及びボールナット、リニアガイド装置のレール及び移動体等）の製造方法の改良に関する。特に本発明は、車輪支持用転がり軸受ユニットや圧延機用ロールネック軸受、ウォータポンプ軸受等、内部に水が浸入し易い環境下で使用される転動装置の軌道部材を製造するのに好適である。 The present invention relates to a race member (an outer ring and an inner ring of a rolling bearing, an outer diameter side race ring member and an inner diameter side race of a rolling bearing unit) that constitute a rolling device (rolling bearing, rolling bearing unit, ball screw device, linear guide device, etc.). The present invention relates to an improvement in a manufacturing method of a ring member, a screw shaft and ball nut of a ball screw device, a rail and a moving body of a linear guide device, and the like. In particular, the present invention is suitable for manufacturing a raceway member for a rolling device used in an environment in which water easily enters inside, such as a rolling bearing unit for supporting a wheel, a roll neck bearing for a rolling mill, and a water pump bearing. is there.

例えば自動車の車輪を懸架装置に対して回転自在に支持する為に、図５に示す様な、車輪支持用転がり軸受ユニット１を使用する。この車輪支持用転がり軸受ユニット１は、独立式の懸架装置に支持する駆動輪（ＦＦ車の前輪、ＦＲ車及びＲＲ車の後輪、４ＷＤ車の全輪）用の車輪支持用転がり軸受ユニットの１例を示している。上記車輪支持用転がり軸受ユニット１を構成する外径側軌道部材である外輪２は、外周面に形成した外向フランジ状の取付部３により、ナックル等の懸架装置に支持固定されて、使用時にも回転しない。この様な外輪２の内径側には、内径側軌道部材であるハブ４を、この外輪２と同心に設けている。 For example, a wheel bearing rolling bearing unit 1 as shown in FIG. 5 is used to rotatably support a vehicle wheel with respect to a suspension device. This wheel-supporting rolling bearing unit 1 is a wheel-supporting rolling bearing unit for driving wheels (front wheels of FF vehicles, rear wheels of FR and RR vehicles, all wheels of 4WD vehicles) supported by an independent suspension device. An example is shown. The outer ring 2 which is an outer diameter side race member constituting the wheel supporting rolling bearing unit 1 is supported and fixed to a suspension device such as a knuckle by an outward flange-shaped mounting portion 3 formed on the outer peripheral surface. Does not rotate. On the inner diameter side of the outer ring 2, a hub 4 that is an inner diameter side race member is provided concentrically with the outer ring 2.

上記ハブ４は、ハブ本体５と内輪６とから成り、このうちのハブ本体５の中心部にはスプライン孔７を、軸方向外（軸方向に関して外とは、車両への組み付け時に幅方向外側になる側を言い、図５の左）端部外周面には、外向フランジ状の取付フランジ８を、それぞれ形成している。又、上記ハブ本体５の軸方向内（軸方向に関して内とは、車両への組み付け時に幅方向中央側になる側を言い、図５の右）端部には、かしめ部９を形成し、このかしめ部９により、上記内輪６の内端面を抑え付けている。車両への組み付け時に、上記スプライン孔７には、図示しない等速ジョイントに付属したスプライン軸を挿入し、上記取付フランジ８には、車輪を固定する。 The hub 4 includes a hub body 5 and an inner ring 6. A spline hole 7 is formed at the center of the hub body 5 out of the axial direction (outside in the axial direction is outside in the width direction when assembled to the vehicle). On the outer peripheral surface of the left end portion, an outward flange-like mounting flange 8 is formed respectively. Further, a caulking portion 9 is formed at an end portion in the axial direction of the hub body 5 (the inner portion in the axial direction means a side that becomes the center side in the width direction when assembled to the vehicle, and the right side in FIG. 5). The caulking portion 9 holds down the inner end surface of the inner ring 6. When assembled to the vehicle, a spline shaft attached to a constant velocity joint (not shown) is inserted into the spline hole 7, and a wheel is fixed to the mounting flange 8.

又、上記外輪２の内周面に複列の外輪軌道１０、１０を、上記ハブ本体５の軸方向中間部外周面と上記内輪６の外周面とに内輪軌道１１、１１を、それぞれ形成している。そして、これら各外輪軌道１０、１０と内輪軌道１１、１１との間に転動体１２、１２を、それぞれ複数個ずつ設けて、上記外輪２の内径側に上記ハブ４を回転自在に支持している。尚、上記各転動体１２、１２は、それぞれ保持器１３、１３により、転動自在に保持している。又、図示の例では転動体１２、１２として玉を使用しているが、重量が嵩む車両用の転がり軸受ユニットの場合には、転動体としてテーパころを使用する場合もある。 Further, double-row outer ring raceways 10 and 10 are formed on the inner peripheral surface of the outer ring 2, and inner ring raceways 11 and 11 are formed on the outer peripheral surface of the hub body 5 in the axial direction intermediate portion and the outer peripheral surface of the inner ring 6, respectively. ing. A plurality of rolling elements 12, 12 are provided between the outer ring raceways 10, 10 and the inner ring raceways 11, 11, and the hub 4 is rotatably supported on the inner diameter side of the outer ring 2. Yes. The rolling elements 12 and 12 are held by the cages 13 and 13 so as to be freely rollable. In the illustrated example, balls are used as the rolling elements 12, 12, but in the case of a rolling bearing unit for a vehicle that is heavy, tapered rollers may be used as the rolling elements.

更に、上記外輪２の軸方向外端部内周面と上記ハブ本体５の軸方向中間部外周面との間、並びに、この外輪２の軸方向内端部内周面と上記内輪６の軸方向内端部外周面との間に、それぞれシール装置１４ａ、１４ｂを設け、上記外輪２の内周面と上記ハブ４の外周面との間で、上記各転動体１２、１２を設置した内部空間１５の軸方向両端開口を塞いでいる。これにより、この内部空間１５への異物の浸入を防止すると共に、この内部空間１５に存在するグリースの漏洩防止を図っている。 Further, between the inner peripheral surface of the outer end of the outer ring 2 in the axial direction and the outer peripheral surface of the intermediate portion of the hub body 5, and the inner peripheral surface of the inner end of the outer ring 2 in the axial direction and the inner periphery of the inner ring 6. Sealing devices 14 a and 14 b are respectively provided between the outer peripheral surfaces of the end portions, and an inner space 15 in which the rolling elements 12 and 12 are installed between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 4. The opening at both axial ends is closed. This prevents foreign matter from entering the internal space 15 and prevents leakage of grease existing in the internal space 15.

ところで、上述の様な車輪支持用転がり軸受ユニット１の場合、使用時に、上記各外輪軌道１０、１０、及び、上記各内輪軌道１１、１１に、上記各転動体１２、１２から高面圧下で繰り返しせん断応力が負荷される。この為、上記外輪、内輪各軌道１０、１１の表面及び表面下に、欠陥（Ａｌ₂Ｏ₃やＳｉＯ₂等の酸化物系介在物及びＴｉＮ等のチタン系介在物に代表される非金属介在物や傷等）が存在すると、上記欠陥にせん断応力が集中し、この欠陥を起点としてフレーキング（早期剥離）を発生させる可能性がある。そして、この様に、上記外輪、内輪各軌道１０、１１にフレーキングが発生した場合には、上記外輪２や上記ハブ４（ハブ本体５、内輪６）の寿命が短くなり、延いては上記車輪支持用転がり軸受ユニット１が短寿命になると言った問題を生じる。この様な問題は、転がり軸受を始めとして、ボールねじ装置、リニアガイド装置でも同様に生じる。 By the way, in the case of the wheel support rolling bearing unit 1 as described above, when used, the outer ring raceways 10 and 10 and the inner ring raceways 11 and 11 are brought into contact with the rolling elements 12 and 12 under high surface pressure. Repeated shear stress is applied. For this reason, defects (non-metallic inclusions typified by oxide inclusions such as Al ₂ O ₃ and SiO ₂ and titanium inclusions such as TiN are formed on the surfaces of the outer ring and inner ring raceways 10 and 11 and below the surfaces. If an object or a flaw is present, shear stress concentrates on the defect, and flaking (early peeling) may occur from the defect. In this way, when flaking occurs in the outer ring and inner ring raceways 10 and 11, the life of the outer ring 2 and the hub 4 (hub body 5 and inner ring 6) is shortened. There arises a problem that the wheel bearing rolling bearing unit 1 has a short life. Such a problem also occurs in a ball screw device and a linear guide device as well as a rolling bearing.

この様な事情に鑑みて、例えば特許文献１には、完成品の軌道部材に対して超音波探傷検査を行う事で、軌道面の表層部（軌道面から転動体の平均直径の２％深さの範囲内）に存在する非金属介在物が、長さ５００μm 未満となるものを選出して使用する事が提案されている。この様にして選出された軌道部材によれば、フレーキングの発生を有効に防止できるが、上記特許文献１の場合には、超音波探傷検査を、素材から完成品の軌道部材にまで加工した状態で初めて行う事としている為、歩留りが悪化し易く、製造コストの上昇を招くと言った問題を生じる。 In view of such circumstances, for example, Patent Document 1 discloses that an ultrasonic flaw detection inspection is performed on a finished race member to obtain a surface layer portion of the raceway surface (2% of the average diameter of the rolling elements from the raceway surface). It has been proposed to select and use non-metallic inclusions having a length of less than 500 μm. According to the track member selected in this way, the occurrence of flaking can be effectively prevented. However, in the case of Patent Document 1, the ultrasonic flaw inspection is processed from the material to the finished track member. Since this is performed for the first time in a state, the yield is likely to deteriorate, resulting in a problem that the manufacturing cost is increased.

これに対し、特許文献２には、完成品の軌道部材に対して超音波探傷検査を行うだけでなく、この軌道部材を造る為の素材に対しても超音波探傷検査を行う、軌道部材の製造方法が記載されている。具体的には、第一工程として、金属製の素材に超音波探傷検査を行い、この素材の単位体積（１．０×１０⁶mm³）あたりに存在する長さ０．５mm以上の非金属介在物の総長さが、８０mm以下であるものを選出する。次いで、第二工程として、この様にして選出された素材に、所定の加工を施し、軌道面を有する軌道部材を形成する。そして最後に、第三工程として、この軌道部材に超音波探傷検査を行い、軌道面の表層部（軌道面から転動体の平均直径の２％深さの範囲内）に存在する全ての非金属介在物に関して、平方根長さが２００μm 以下となるものを選出する。 On the other hand, Patent Document 2 discloses a track member that performs not only an ultrasonic flaw inspection on a finished track member but also an ultrasonic flaw inspection on a material for making the track member. A manufacturing method is described. Specifically, as a first step, ultrasonic flaw detection is performed on a metal material, and a non-metal having a length of 0.5 mm or more existing per unit volume (1.0 × 10 ⁶ mm ³ ) of the material. Those whose total length of inclusions is 80 mm or less are selected. Next, as a second step, the material selected in this way is subjected to predetermined processing to form a track member having a track surface. Finally, as a third step, ultrasonic inspection is performed on this raceway member, and all non-metallic materials existing in the surface layer portion of the raceway surface (within a range of 2% of the average diameter of the rolling elements from the raceway surface). Regarding inclusions, those having a square root length of 200 μm or less are selected.

この様な特許文献２に記載された製造方法によれば、上記第一工程で、要件を満たさない素材を、所定の加工を施す以前に不合格品として排除できる為、軌道部材にまで加工した後に廃材となるものの割合を少なくできる。従って、歩留りの低下を抑え、製造コストの上昇を抑えられる。但し、上記特許文献２に記載された製造方法により得られる軌道部材の場合にも、前述した車輪支持用転がり軸受ユニット１の様に、過酷な環境下で使用される用途に用いた場合には、フレーキングの発生を十分に防止できなくなる可能性がある。この理由は、以下の通りである。 According to the manufacturing method described in Patent Document 2 as described above, in the first step, since the material that does not satisfy the requirements can be excluded as a rejected product before performing the predetermined processing, it is processed into the race member. The percentage of what will later be scrapped can be reduced. Therefore, it is possible to suppress a decrease in yield and suppress an increase in manufacturing cost. However, even in the case of a raceway member obtained by the manufacturing method described in Patent Document 2 above, when used for an application used in a harsh environment, such as the wheel bearing rolling bearing unit 1 described above, The occurrence of flaking may not be sufficiently prevented. The reason for this is as follows.

即ち、上記車輪支持用転がり軸受ユニット１の周辺環境には、雨水、洗車時の水、泥水、更には水蒸気等の水分が存在する。この為、前述した様なシール装置１４ａ、１４ｂによっても、前記内部空間１５への水の浸入を完全に防止する事は難しく、若干の水がこの内部空間１５に浸入する可能性がある。そして、この内部空間１５に水が浸入すると、この水は腐食反応によって水素となり、この水素が、前記外輪２及び前記ハブ４を構成する鋼中に浸入する可能性がある。この様に水素が浸入すると、当該部分が脆くなる為、前記外輪、内輪各軌道１０、１１の表層部に存在する、平方根長さが２００μm 以下の非金属介在物もがフレーキングの起点となる可能性を生じる。 That is, the surrounding environment of the wheel support rolling bearing unit 1 includes water such as rain water, water during car washing, muddy water, and water vapor. For this reason, even with the sealing devices 14a and 14b as described above, it is difficult to completely prevent water from entering the internal space 15, and some water may enter the internal space 15. When water enters the internal space 15, the water becomes hydrogen due to a corrosion reaction, and this hydrogen may enter the steel constituting the outer ring 2 and the hub 4. When hydrogen penetrates in this way, the portion becomes brittle, and non-metallic inclusions having a square root length of 200 μm or less that are present in the surface layer portions of the outer ring and inner ring raceways 10 and 11 also become the starting point of flaking. Create a possibility.

この様な水を原因として発生するフレーキングを防止する為に、例えば、前記第一工程及び前記第三工程で行う超音波探傷検査を、超音波の周波数を高くする等して行い、より清浄度の高い素材及び軌道部材を選出する（より小さな非金属介在物が含まれる素材及び軌道部材を不合格品として排除する）事が考えられる。但し、この様に、合否判定の基準となる欠陥の大きさを単に小さくした場合には、歩留りが悪くなり、製造コストの上昇を招く為、採用する事は難しい。又、上記素材として、予め清浄度の高いものを使用する事も考えられるが、この場合には、この素材を調達しにくくなったり、この素材の生産性が低下し、材料コストが上昇する等の問題を生じる為、やはり採用する事は難しい。 In order to prevent flaking caused by such water, for example, the ultrasonic flaw detection performed in the first step and the third step is performed by increasing the frequency of the ultrasonic wave, thereby purifying more clearly. It is conceivable to select materials and track members having a high degree (excluding materials and track members containing smaller non-metallic inclusions as rejected products). However, if the size of the defect serving as a criterion for the pass / fail judgment is simply reduced in this way, the yield deteriorates and the manufacturing cost increases, which is difficult to adopt. In addition, it is conceivable to use a material having a high cleanliness as the material in advance, but in this case, it becomes difficult to procure the material, productivity of the material decreases, and material cost increases. It is still difficult to adopt because it causes problems.

一方、特許文献３には、上述の様な超音波探傷検査を利用する事なく、非金属介在物の分布のばらつきを利用して、フレーキングの発生防止を図る、軌道部材の製造方法が記載されている。即ち、上記特許文献３に記載された製造方法の場合には、素材として円柱状の素材（円柱状素材）を使用する事で、非金属介在物が、外径寄り部分に比べて中心寄り部分に集中し易くなると言った特性を利用する。そして、上記円柱状素材の外周面からこの円柱状素材の外径寸法の３０％深さの範囲内に存在する部分（円柱状素材の径方向で中心から半径の４０％となる位置より外側の部分）から、軌道面の表層部を形成する事としている。 On the other hand, Patent Document 3 describes a method for manufacturing a raceway member that prevents occurrence of flaking by using variation in the distribution of non-metallic inclusions without using the ultrasonic flaw detection as described above. Has been. That is, in the case of the manufacturing method described in Patent Document 3, a non-metallic inclusion is a portion closer to the center than the portion closer to the outer diameter by using a columnar material (columnar material) as the material. Take advantage of the characteristics that make it easier to focus on. And the part (outside the position which becomes 40% of the radius from the center in the radial direction of the cylindrical material in the radial direction of the cylindrical material) within the range of 30% depth of the outer diameter of the cylindrical material from the outer peripheral surface of the cylindrical material The surface layer portion of the raceway surface is formed from the portion).

上述の様な特許文献３に記載された製造方法によれば、上記軌道面の表層部を、上記円柱状素材のうちで、非金属介在物が存在しにくくなる部分（清浄度の高い部分）を利用して形成できる。この為、上記円柱状素材として、全体の清浄度がそれ程高くないものを使用した場合にも、フレーキングの発生を有効に防止できる。 According to the manufacturing method described in Patent Document 3 as described above, the surface layer portion of the raceway surface is a portion where non-metallic inclusions are less likely to be present in the cylindrical material (a portion having a high cleanliness). Can be formed using For this reason, the occurrence of flaking can be effectively prevented even when the above-mentioned columnar material is used that is not so clean as a whole.

但し、上記特許文献３に記載された製造方法の場合には、非金属介在物の分布のばらつきを、円柱状素材毎に検査する事を意図していない為、形成される軌道面の表層部中に、当初想定していた以上の数（或は大きさ）の非金属介在物が含まれる可能性がある。又、上記円柱状素材から上記軌道部材にまで成形する過程（例えば鍛造加工や研削加工等）で、上記軌道面に傷や割れが生じたり、この軌道面の表層部に非金属介在物が出現する可能性もある。 However, in the case of the manufacturing method described in the above-mentioned Patent Document 3, since it is not intended to inspect the variation in the distribution of nonmetallic inclusions for each cylindrical material, the surface layer portion of the raceway surface to be formed There may be a greater number (or size) of non-metallic inclusions than initially envisaged. Also, in the process of molding from the cylindrical material to the raceway member (for example, forging or grinding), the raceway surface is scratched or cracked, or non-metallic inclusions appear on the surface layer of the raceway surface There is also a possibility to do.

尚、完成品の軌道部材に対しては、漏洩磁束探傷検査が広く行われているが、この漏洩磁束探傷検査では、水を原因とするフレーキングの起点となる様な小さな欠陥を検出する事は不可能である。この為、上述の様な原因で、上記軌道面の表層部に、水を原因とするフレーキングの起点となる様な小さな欠陥が存在した場合には、仮に漏洩磁束探傷検査を行った場合にも、この様な欠陥を有する軌道部材を排除する事はできない。従って、上記特許文献３に記載された製造方法により得られる軌道部材の場合には、フレーキングの発生を安定して防止する事が難しく、寿命にばらつきを生じる可能性がある。 In addition, leaked magnetic flux inspection is widely performed on the finished track member, but this leakage magnetic flux inspection detects small defects that may cause flaking caused by water. Is impossible. For this reason, if there is a small defect in the surface layer of the raceway surface that causes water-induced flaking, for example, if a leakage magnetic flux inspection is performed. However, the track member having such a defect cannot be excluded. Therefore, in the case of the raceway member obtained by the manufacturing method described in Patent Document 3, it is difficult to stably prevent the occurrence of flaking, and there is a possibility that the life will vary.

特開２０００−１３０４４７号公報JP 2000-130447 A 特開２００５−２０１３３０号公報JP 2005-201330 A 特開２００６−２５０３１７号公報JP 2006-250317 A

本発明は、上述の様な事情に鑑み、転動装置の内部に水が浸入する等の過酷な環境下で使用した場合にも、フレーキングの発生を有効に防止して長寿命化を図る事ができ、且つ、寿命のばらつきを抑えられる軌道部材を、低コストで得られる製造方法を実現すべく発明したものである。 In view of the circumstances as described above, the present invention effectively prevents flaking and prolongs the life even when used in a harsh environment such as when water enters the inside of a rolling device. The invention has been invented to realize a manufacturing method that can obtain a low-cost raceway member that can reduce the variation in life.

本発明の転動装置用軌道部材の製造方法は、互いに対向する面にそれぞれ軌道面を有する１対の軌道部材と、これら両軌道面同士の間に転動自在に設けられた複数個の転動体とを備えた転動装置を構成する、上記両軌道部材のうちの少なくとも一方の軌道部材を、金属製の円柱状素材から造る為に利用する。
特に本発明の転動装置用軌道部材の製造方法の場合には、次の第一工程から第三工程を備える。
先ず、第一工程として、上記円柱状素材に超音波探傷検査を行う事により、この円柱状素材の外周面からこの円柱状素材の外径寸法の３０％深さの範囲内に、所定の大きさ（例えば平方根長さが２００μm ）以上の欠陥（非金属介在物や傷等）が存在しないものを選出する。
次に、第二工程として、選出された円柱状素材に所定の加工（例えば鍛造加工）を施す事により、軌道面の表層部（例えば軌道面から転動体の平均直径の２％深さの範囲）が、上記円柱状素材のうちで、外周面からこの円柱状素材の外径寸法の３０％深さの範囲内に存在する部分のみから形成された、軌道部材を得る。
最後に、第三工程として、得られた軌道部材に超音波探傷検査を行う事により、この軌道部材に形成された軌道面の表層部に、所定の大きさ（例えば平方根長さが１８０μm 、好ましくは１５０μm 、より好ましくは１２０μm 、更に好ましくは１００μm ）以上の欠陥が存在しないものを選出する。 The manufacturing method of the raceway member for a rolling device according to the present invention includes a pair of raceway members each having raceway surfaces on opposite surfaces, and a plurality of roll members provided between the raceway surfaces so as to be freely rollable. At least one of the two track members constituting the rolling device including a moving body is used to make a metal columnar material.
In particular, in the case of the method for manufacturing a rolling member raceway member according to the present invention, the following first to third steps are provided.
First, as a first step, an ultrasonic flaw inspection is performed on the columnar material, so that a predetermined size is obtained within a range of 30% of the outer diameter of the columnar material from the outer peripheral surface of the columnar material. Those having no defects (non-metallic inclusions, scratches, etc.) of more than (for example, a square root length of 200 μm) are selected.
Next, as a second step, the selected columnar material is subjected to predetermined processing (for example, forging), whereby the surface layer portion of the raceway surface (for example, a range of 2% depth of the average diameter of the rolling elements from the raceway surface). ) Is a track member formed only from a portion of the cylindrical material within a range of 30% depth of the outer diameter of the cylindrical material from the outer peripheral surface.
Finally, as a third step, the obtained raceway member is subjected to ultrasonic flaw detection, whereby the surface layer portion of the raceway surface formed on this raceway member has a predetermined size (for example, a square root length of 180 μm, preferably Is selected from those having no defects of 150 μm, more preferably 120 μm, and still more preferably 100 μm).

又、本発明の場合には、上記第一工程の超音波探傷検査で、超音波を送波する為の探触子に印加する電圧（円柱状素材の外周面に対して送波する超音波の出力）を、上記第三工程の超音波探傷検査で、超音波を送波する為の探触子に印加する電圧（軌道部材の軌道面に対して送波する超音波の出力）よりも高くする。 In the case of the present invention, the voltage applied to the probe for transmitting ultrasonic waves in the ultrasonic flaw inspection in the first step (the ultrasonic waves transmitted to the outer peripheral surface of the cylindrical material). the output), in ultrasonic testing of the third step, than the voltage applied to the probe for transmitting ultrasonic waves (output of the ultrasonic wave transmitting against the raceway surface of the raceway member) Make it high.

上述した様な本発明の転動装置用軌道部材の製造方法によれば、転動装置の内部に水が浸入する等の過酷な環境下で使用した場合にも、フレーキングの発生を有効に防止して長寿命化を図る事ができ、且つ、寿命のばらつきを抑えられる軌道部材を、低コストで得られる。
即ち、本発明の場合には、素材として、非金属介在物の分布にばらつきを生じる円柱状素材を使用し、第二工程で、この円柱状素材のうちで清浄度の高くなった部分から、軌道面の表層部を形成する。この為、上記第二工程の前後に行う、第一工程及び第三工程の超音波探傷検査を、前述した特許文献２に記載された製造方法（の第一工程及び第三工程）の場合に比べて、清浄度の高い部分を対象に（探傷範囲として）行う事が可能となる。この為、上記特許文献２に記載された製造方法の場合に比べて、合否判定の基準となる欠陥の大きさを小さくする事による、歩留りの低下を抑えられる。従って、本発明の場合には、水を原因とするフレーキングの起点となる様な小さな欠陥を、上記第三工程での合否判定の基準とした場合にも、製造コストの上昇を十分に抑えられる。この結果、本発明の場合には、水を原因とするフレーキングの発生を有効に防止できて、長寿命化を図れる軌道部材を、低コストで得られる。 According to the manufacturing method of the raceway member for a rolling device of the present invention as described above, even when used in a harsh environment such as when water enters the inside of the rolling device, the occurrence of flaking is effectively performed. Thus, a track member that can be prevented to have a long service life and suppress variations in the service life can be obtained at low cost.
That is, in the case of the present invention, as a material, a cylindrical material that causes variations in the distribution of non-metallic inclusions is used, and in the second step, from the portion with a high degree of cleanliness among the cylindrical material, The surface layer portion of the raceway surface is formed. For this reason, in the case of the manufacturing method (the 1st process and the 3rd process) described in patent documents 2 mentioned above, the ultrasonic inspection of the 1st process and the 3rd process performed before and after the 2nd process is carried out. In comparison, it is possible to perform a target (as a flaw detection range) on a portion with a high cleanliness. For this reason, compared with the case of the manufacturing method described in the above-mentioned Patent Document 2, it is possible to suppress a decrease in yield caused by reducing the size of a defect serving as a criterion for pass / fail judgment. Therefore, in the case of the present invention, even if a small defect that becomes the starting point of flaking caused by water is used as a criterion for the pass / fail judgment in the third step, the increase in manufacturing cost is sufficiently suppressed. It is done. As a result, in the case of the present invention, it is possible to effectively prevent the occurrence of flaking caused by water, and to obtain a track member that can extend the service life at low cost.

又、本発明の場合には、上述した様に、上記第二工程で、上記円柱状素材のうちで清浄度の高くなった部分のみから、上記軌道面の表層部を形成する為、この円柱状素材として、全体の清浄度がそれ程高くないものを使用できる。この為、材料コストの上昇を抑える事もできる。 Further, in the case of the present invention, as described above, in the second step, since the surface layer portion of the raceway surface is formed only from the portion of the cylindrical material having a high degree of cleanliness, this circle is formed. As the columnar material, a material whose overall cleanliness is not so high can be used. For this reason, the increase in material cost can also be suppressed.

又、本発明の場合には、上記軌道面の表層部を、上記第一工程で清浄度の保証された部分から形成するだけでなく、この軌道面の表層部を対象として、上記第三工程で超音波探傷検査を行う。この為、この軌道面の表層部の清浄度に関して、高い信頼性を確保できる。従って、本発明の場合には、前述した特許文献３に記載された製造方法の場合に比べて、フレーキングの発生を安定して防止でき、寿命のばらつきを抑えられる軌道部材を得られる。 Further, in the case of the present invention, not only the surface layer portion of the raceway surface is formed from the portion where the cleanliness is guaranteed in the first step, but also the surface layer portion of the raceway surface is used as a target. Perform an ultrasonic flaw inspection. For this reason, high reliability can be ensured regarding the cleanliness of the surface layer portion of the raceway surface. Therefore, in the case of the present invention, compared with the manufacturing method described in Patent Document 3 described above, it is possible to stably prevent the occurrence of flaking and to obtain a track member that can suppress the variation in life.

更に、本発明の場合には、上記第一工程で、素材である円柱状素材に対して超音波探傷検査を行う為、上記第三工程の超音波探傷検査で、完成品である軌道部材が不合格品となる割合を低くする事ができる。この為、歩留りの低下を抑え、製造コストの上昇を抑えられる。又、本発明の場合には、上記第一工程の超音波探傷検査で、超音波を送波する為の探触子に印加する電圧（円柱状素材の外周面に対して送波する超音波の出力）を、上記第三工程の超音波探傷検査で、超音波を送波する為の探触子に印加する電圧（軌道部材の軌道面に対して送波する超音波の出力）よりも高くしている為、探傷深さが深くなる上記第一工程で行う超音波探傷検査に就いて、十分な精度を確保できる。 Furthermore, in the case of the present invention, since the ultrasonic inspection is performed on the cylindrical material as the material in the first step, the track member which is a finished product is obtained in the ultrasonic inspection of the third step. The ratio of rejected products can be lowered. For this reason, a decrease in yield can be suppressed and an increase in manufacturing cost can be suppressed. In the case of the present invention, the voltage applied to the probe for transmitting ultrasonic waves in the ultrasonic flaw inspection in the first step (the ultrasonic waves transmitted to the outer peripheral surface of the cylindrical material). Output) than the voltage applied to the probe for transmitting ultrasonic waves in the ultrasonic flaw inspection in the third step (output of ultrasonic waves transmitted to the track surface of the track member) Since the height is high, sufficient accuracy can be ensured for the ultrasonic flaw detection performed in the first step in which the flaw detection depth is increased.

図１〜４は、本発明の実施の形態の１例を示している。本例では、前記図５に示した様な、車輪支持用転がり軸受ユニット１を構成する外輪２を対象として、その製造方法を説明する。本例の場合、図３に示す様に、この外輪２を造る為の素材として、高炭素クロム軸受鋼（ＳＵＪ２）製で、外径寸法が１３０mmの円柱状素材１６を使用する。そして、第一工程として、この様な円柱状素材１６に超音波探傷検査を行い、この円柱状素材１６の外周面からこの円柱状素材１６の外径寸法の３０％深さ（約３９mm）の範囲内に、平方根長さで２００μm 以上の欠陥（非金属介在物や傷等）が存在しない円柱状素材１６を、合格品として選出する。この為に、本例の場合には、図１に示す様な、超音波探傷装置１７を使用する。 1 to 4 show an example of an embodiment of the present invention . In this example, the manufacturing method will be described with respect to the outer ring 2 constituting the wheel bearing rolling bearing unit 1 as shown in FIG. In the case of this example, as shown in FIG. 3, a columnar material 16 made of high carbon chromium bearing steel (SUJ2) and having an outer diameter of 130 mm is used as a material for producing the outer ring 2. Then, as a first step, such a cylindrical material 16 is subjected to ultrasonic flaw inspection, and the outer diameter of the cylindrical material 16 is 30% deep (about 39 mm) of the outer diameter of the cylindrical material 16. A columnar material 16 having no defects (non-metallic inclusions, scratches, etc.) having a square root length of 200 μm or more within the range is selected as an acceptable product. Therefore, in this example, an ultrasonic flaw detector 17 as shown in FIG. 1 is used.

この超音波探傷装置１７は、超音波伝達媒体である水（防錆剤を含む）を貯留した水槽１８と、探触子１９と、探傷器２０と、ワーク回転装置２１と、探触子位置調節装置２２と、モータコントローラ２３と、制御器２４とから構成される。この様な構成を有する超音波探傷装置１７を用いて超音波探傷検査を行うには、先ず、上記円柱状素材１６を、上記水槽１８の底部に設けられた上記ワーク回転装置２１上に載置する。次いで、上記探触子１９を、上記探触子位置調節装置２２により所定位置（例えば円柱状素材１６の軸方向端部）に移動させて、上記探触子１９の先端部を、上記円柱状素材１６の外周面に対向させる。尚、この様に、この探触子１９の先端部を、この円柱状素材１６の外周面に対向させた状態で、この探触子１９に就いても、上記水槽１８内の水に浸漬する。 The ultrasonic flaw detector 17 includes a water tank 18 that stores water (including a rust preventive agent) that is an ultrasonic transmission medium, a probe 19, a flaw detector 20, a workpiece rotating device 21, and a probe position. The controller 22 includes a motor controller 23, and a controller 24. In order to perform ultrasonic flaw detection using the ultrasonic flaw detector 17 having such a configuration, first, the columnar material 16 is placed on the work rotating device 21 provided at the bottom of the water tank 18. To do. Next, the probe 19 is moved to a predetermined position (for example, the axial end of the columnar material 16) by the probe position adjusting device 22, and the tip of the probe 19 is moved to the columnar shape. It is made to oppose the outer peripheral surface of the raw material 16. In this way, the probe 19 is immersed in the water in the water tank 18 with the tip of the probe 19 facing the outer peripheral surface of the columnar material 16 in this manner. .

そして、上記制御器２４からの指令に基づき、上記探傷器２０から上記探触子１９に所定の大きさの電圧を印加する（電圧信号を送信する）。これにより、この探触子１９から上記円柱状素材１６の外周面に向けて、上記電圧の大きさに応じた出力（出力レベル）の超音波（パルス波）を送波すると共に、エコー（反射波）をこの探触子１９により受波し、このエコーを電圧信号に変換して、上記探傷器２０に送信する。本例の場合には、この様な探傷作業を、上記円柱状素材１６を、上記ワーク回転装置２１により一方向に所定速度で回転させつつ、上記探触子１９を、上記探触子位置調節装置２２により上記円柱状素材１６の軸方向（図１の左右方向）に移動させながら行う（走査する）。尚、上記ワーク回転装置２１は、モータ２５ａにより回転駆動され、上記探触子位置調節装置２２は、モータ２５ｂにより駆動される。又、これら両モータ２５ａ、２５ｂは、上記モータコントローラ２３により制御され、このモータコントローラ２３は、ＰＣ等の制御器２４への入力値により作動が制御される。 Then, based on a command from the controller 24, a voltage having a predetermined magnitude is applied from the flaw detector 20 to the probe 19 (a voltage signal is transmitted). As a result, an ultrasonic wave (pulse wave) having an output (output level) corresponding to the magnitude of the voltage is transmitted from the probe 19 toward the outer peripheral surface of the cylindrical material 16 and echo (reflection) is performed. Wave) is received by the probe 19, the echo is converted into a voltage signal, and transmitted to the flaw detector 20. In the case of this example, such a flaw detection operation is performed by adjusting the position of the probe 19 while rotating the cylindrical material 16 at a predetermined speed in one direction by the work rotating device 21. It is performed (scanned) while being moved in the axial direction (left-right direction in FIG. 1) of the cylindrical material 16 by the device 22. The workpiece rotating device 21 is driven to rotate by a motor 25a, and the probe position adjusting device 22 is driven by a motor 25b. The motors 25a and 25b are controlled by the motor controller 23. The operation of the motor controller 23 is controlled by an input value to a controller 24 such as a PC.

上記探傷器２０では、上記探触子１９に送信した電圧信号と、この探触子１９から受信した電圧信号とを基に、上記円柱状素材１６の外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲の欠陥の有無、及び、欠陥が存在する場合にはその大きさを計測する。そして、この探傷情報を上記制御器２４に送信する。この様にして、本例の場合には、上記円柱状素材１６の外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲内に、平方根長さで２００μm 以上の欠陥が存在しない事を確認（保証）された円柱状素材１６を、合格品として選出する。 In the flaw detector 20, based on the voltage signal transmitted to the probe 19 and the voltage signal received from the probe 19, the outer diameter of the columnar material 16 from the outer peripheral surface of the columnar material 16. The presence / absence of a defect in the range of 30% depth of the dimension and the size of the defect are measured. Then, the flaw detection information is transmitted to the controller 24. Thus, in the case of this example, a defect having a square root length of 200 μm or more exists within the range of 30% of the outer diameter of the cylindrical material 16 from the outer peripheral surface of the cylindrical material 16. The columnar material 16 that is confirmed (guaranteed) not to be selected is selected as an acceptable product.

尚、欠陥の平方根長さとは、欠陥の形状が線状（線状欠陥）である場合は、その長さＬと幅Ｗとの積の平方根（Ｌ×Ｗ）^1/2を言い、欠陥の形状が粒状、球状又は塊状である（非線状欠陥）である場合には、その最大径（長径）Ｄ₁と最小径（短径）Ｄ₂との積の平方根（Ｄ₁×Ｄ₂）^1/2を言う。又、上述の様な第一工程では、上記探触子１９として、指向性が高く、上記円柱状素材１６の外周面の曲率の影響を受けにくい、焦点型の探触子を使用できる。又、この様な焦点型の探触子としては、周波数が５〜５０ＭHz、振動子径が３〜２０mmのものを使用できる。 The square root length of the defect means the square root (L × W) ^1/2 of the product of the length L and the width W when the shape of the defect is linear (linear defect). When the shape is granular, spherical or massive (non-linear defect), the square root (D ₁ × D ₂ ) of the product of its maximum diameter (major axis) D ₁ and minimum diameter (minor axis) D ₂ Say ^1/2 . In the first step as described above, a focus type probe having high directivity and being hardly affected by the curvature of the outer peripheral surface of the cylindrical material 16 can be used as the probe 19. As such a focus type probe, one having a frequency of 5 to 50 MHz and a vibrator diameter of 3 to 20 mm can be used.

ここで、上述の様な第一工程により選出された円柱状素材１６に就いて、この円柱状素材１６を構成する金属材料中に含まれる非金属介在物の分布状態（数）を、光学顕微鏡により確認した結果の１例を、図２に示す。尚、この図２は、実際に光学顕微鏡を用いて上記円柱状素材１６の径方向各位置を観察し、観察領域が重複しない様に、各位置毎に、合計の観察面積が３００mm²になるまで、複数回観察する事により得られた結果を示している。横軸の「円柱状素材の径方向位置（％）」は、円柱状素材１６の中心（０％）から外周面（１００％）までの径方向位置に対応し、縦軸の「非金属介在物数（個）」は、観察面積３００mm²に存在する、直径１０μm 以上の非金属介在物の数を表している。 Here, regarding the columnar material 16 selected by the first step as described above, the distribution state (number) of non-metallic inclusions contained in the metal material constituting the columnar material 16 is measured with an optical microscope. FIG. 2 shows an example of the result confirmed by the above. In FIG. 2, each position in the radial direction of the cylindrical material 16 is actually observed using an optical microscope, and the total observation area is 300 mm ² for each position so that the observation areas do not overlap. Until now, the results obtained by observing multiple times are shown. The “columnar material radial position (%)” on the horizontal axis corresponds to the radial position from the center (0%) to the outer peripheral surface (100%) of the columnar material 16, and “non-metallic interposition on the vertical axis” The “number of objects (pieces)” represents the number of non-metallic inclusions having a diameter of 10 μm or more existing in an observation area of 300 mm ² .

上記図２からも明らかな様に、直径１０μm 以上の非金属介在物は、上記円柱状素材１６の中心寄り部分に多く存在し、この円柱状素材１６の外径寄り部分には、あまり存在しない。これは、本例が、前記外輪２を造る為の素材として、一体押出加工により造られて、非金属介在物が中心寄り部分に集中し易くなると言った特性を有する、上記円柱状素材１６を使用すると共に、上述した第一工程で、この円柱状素材１６の外径寄り部分（外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲）に、平方根長さで２００μm 以上の欠陥が存在しないものを選出した為である。 As is clear from FIG. 2 above, many non-metallic inclusions having a diameter of 10 μm or more are present in the portion near the center of the columnar material 16 and are not so present in the portion near the outer diameter of the columnar material 16. . This is because the cylindrical material 16 has the characteristics that this example is produced by integral extrusion as a material for producing the outer ring 2, and non-metallic inclusions tend to concentrate on the central portion. In addition to being used, in the first step described above, a portion with a square root length of 200 μm or more in a portion near the outer diameter of the columnar material 16 (range from the outer peripheral surface to a depth of 30% of the outer diameter of the columnar material 16) This is because the one having no defect is selected.

従って、続く第二工程で、上記円柱状素材１６のうちで外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲（図２の４０〜１００％の範囲）に存在する部分のみから、上記外輪２のうちで、少なくとも外輪軌道１０、１０の表層部｛外輪軌道１０、１０の表面から、転動体１２、１２（図５参照）の平均直径の２％深さの範囲を指し、以下、単に「表層部」と呼ぶ。｝を形成する事で、上記各外輪軌道１０、１０の表層部中に含まれる非金属介在物の数を、十分に且つ確実に少なくできる事が確認できる。尚、上述の様に、上記各外輪軌道１０、１０の表層部の範囲を規制した理由は、これら各外輪軌道１０、１０に上記各転動体１２、１２から作用するせん断応力が最大となる深さが、これら各転動体１２、１２の平均直径の２％未満となる為である。 Therefore, in the subsequent second step, a portion of the columnar material 16 that exists in the range of 30% depth (the range of 40 to 100% in FIG. 2) of the outer diameter of the columnar material 16 from the outer peripheral surface. From the above, in the outer ring 2, at least the surface layer portion of the outer ring raceways 10 and 10 (the range of the depth of 2% of the average diameter of the rolling elements 12 and 12 (see FIG. 5) from the surface of the outer ring raceways 10 and 10) Hereinafter, it is simply referred to as “surface layer part”. } Can be confirmed that the number of non-metallic inclusions contained in the surface layer portions of the outer ring raceways 10 and 10 can be sufficiently and reliably reduced. As described above, the reason why the range of the surface layer portion of the outer ring raceways 10 and 10 is regulated is that the depth at which the shear stress acting on the outer ring raceways 10 and 10 from the rolling elements 12 and 12 is maximized. This is because the rolling elements 12 and 12 are less than 2% of the average diameter.

上述の様な第一工程により選出された上記円柱状素材１６には、続く第二工程で、所定の加工を施す事により、上記外輪２を得る。特に本例の場合には、上記各外輪軌道１０、１０の表層部を、上記円柱状素材１６のうちで、外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲に存在する部分のみから形成する。この様な第二工程に就いて、以下、図３を参照しつつ説明する。 The columnar material 16 selected in the first step as described above is subjected to predetermined processing in the subsequent second step to obtain the outer ring 2. Particularly in the case of this example, the surface layer portion of each of the outer ring raceways 10, 10 exists in the range of 30% of the outer diameter of the columnar material 16 from the outer peripheral surface of the columnar material 16. It is formed only from the part to be. Such a second process will be described below with reference to FIG.

先ず、上記円柱状素材１６に、軸方向に圧縮する据え込み加工を施して、同図の（ｂ）に示した様な、軸方向寸法が短く且つ直径が大きい短円柱状の第一中間素材２６を得る。次いで、この第一中間素材２６に鍛造加工を施して、同図の（ｃ）に示した様な、得るべき外輪２の大まかな形状を有する、第二中間素材２７を得る。この第二中間素材２７には、軸方向中間部外周面に取付部３を、軸方向中間部内周面に１対の外輪軌道１０、１０を、これら両外輪軌道１０、１０同士の間に隔壁部２８を、それぞれ形成している。そして、この様な形状を有する上記第二中間素材２７に、ピアス加工を施す事により、上記隔壁部２８を打ち抜いて、同図の（ｄ）に示す様な外輪２を得る。尚、上記両外輪軌道１０、１０部分には、必要とする旋削加工及び研削加工に加えて、焼き入れ処理を施す。 First, the columnar material 16 is subjected to upsetting to be compressed in the axial direction, and the short intermediate cylindrical first material having a short axial dimension and a large diameter as shown in FIG. 26 is obtained. Next, the first intermediate material 26 is forged to obtain a second intermediate material 27 having a rough shape of the outer ring 2 to be obtained, as shown in FIG. The second intermediate material 27 includes an attachment portion 3 on the outer peripheral surface in the axial direction intermediate portion, a pair of outer ring raceways 10 and 10 on the inner peripheral surface in the axial direction intermediate portion, and a partition between the outer ring raceways 10 and 10. Each part 28 is formed. The partition wall 28 is punched out by piercing the second intermediate material 27 having such a shape to obtain the outer ring 2 as shown in FIG. The outer ring raceways 10 and 10 are subjected to quenching in addition to the necessary turning and grinding.

本例の場合には、上述の様な各工程を採用する事で、上記円柱状素材１６の中心寄り部分（清浄度の低くなった部分）を構成する金属材料から、上述したピアス加工により除去される、上記隔壁部２８を形成する様にしている。これにより、上記円柱状素材１６の外径寄り部分（清浄度の高くなった部分）を構成する金属材料から、上記両外輪軌道１０、１０の表層部を含む、上記外輪２の大部分を形成している。この為に、本例の場合には、上記据え込み加工時に、上記第一中間素材２６の外径寸法と軸方向寸法との比を調整すると共に、上記鍛造加工時に、上記隔壁部２８の軸方向位置（形成位置）及び軸方向厚さ（肉厚）を調整している。この様に、本例の場合には、金属材料の移動位置を適正に規制し易い鍛造加工を利用する事で、上記両外輪軌道１０、１０の表層部を、前述した第一工程により清浄度を保証された部分（円柱状素材１６のうちで外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲に存在する部分）のみから確実に形成している。 In the case of this example, by adopting each process as described above, it is removed from the metal material constituting the portion near the center of the cylindrical material 16 (the portion with a low cleanliness) by the piercing process described above. The partition wall 28 is formed. As a result, most of the outer ring 2 including the surface layer portions of the outer ring raceways 10 and 10 is formed from the metal material constituting the portion closer to the outer diameter of the columnar material 16 (the portion with higher cleanliness). is doing. For this reason, in the case of this example, the ratio of the outer diameter dimension of the first intermediate material 26 to the axial dimension is adjusted during the upsetting process, and the shaft of the partition wall 28 is adjusted during the forging process. The direction position (formation position) and the axial thickness (wall thickness) are adjusted. Thus, in the case of this example, by using a forging process that easily regulates the movement position of the metal material, the surface layer portions of the outer ring raceways 10 and 10 are cleaned by the first step described above. Is assuredly formed only from a portion that is guaranteed (a portion of the cylindrical material 16 within a range of 30% depth of the outer diameter of the cylindrical material 16 from the outer peripheral surface).

尚、本例の場合には、上述の様なピアス加工の後、上記両外輪軌道１０、１０の表層部を対象とした超音波探傷検査を行う前に、これら両外輪軌道１０、１０に対して、旋削加工及び研削加工を施している。この理由は、これら両外輪軌道１０、１０の形状精度及び寸法精度を確保すると共に、後述する第三工程で、これら両外輪軌道１０、１０の表層部を対象とした超音波探傷検査を行う際に、これら両外輪軌道１０、１０に送波された超音波が乱反射する事を防止する為である。更に、この超音波探傷検査後に旋削加工及び研削加工を施す事で、非金属介在物等の欠陥が上記各外輪軌道１０、１０の表層部に新たに出現したり、この研削加工時にこれら各外輪軌道１０、１０に傷や割れ等の欠陥が生じる事を防止する為である。 In the case of this example, after the piercing process as described above, before performing the ultrasonic flaw inspection on the surface layer portions of the outer ring raceways 10, 10, the outer ring raceways 10, 10 are processed. Turning and grinding. The reason for this is that the shape accuracy and dimensional accuracy of both outer ring raceways 10 and 10 are ensured, and the ultrasonic flaw inspection is performed on the surface layer portions of both outer ring raceways 10 and 10 in the third step described later. In addition, the ultrasonic waves transmitted to the outer ring raceways 10 and 10 are prevented from being irregularly reflected. Further, by performing turning and grinding after the ultrasonic flaw detection inspection, defects such as non-metallic inclusions newly appear on the surface layer portions of the outer ring raceways 10 and 10, and during the grinding process, This is for preventing defects such as scratches and cracks on the tracks 10 and 10.

上述の様な第二工程により、上記外輪２を形成した後は、第三工程として、この外輪２の超音波探傷検査を行う。そして、この外輪２に形成された上記各外輪軌道１０、１０の表層部に、平方根長さが１００μm 以上の欠陥（非金属介在物や傷等）が存在しない外輪２を、合格品として選出する。この為に、本例の場合には、図４に示す様な、超音波探傷装置１７ａを使用する。 After the outer ring 2 is formed by the second process as described above, an ultrasonic flaw inspection of the outer ring 2 is performed as a third process. Then, the outer ring 2 having a square root length of 100 μm or more on the surface layer portion of each of the outer ring races 10 and 10 formed on the outer ring 2 is selected as an acceptable product. . Therefore, in this example, an ultrasonic flaw detector 17a as shown in FIG. 4 is used.

上記超音波探傷装置１７ａは、超音波伝達媒体である白灯油（防錆剤を含む）を貯留した液槽２９と、探触子１９ａと、探傷器２０ａと、ワーク回転装置２１ａと、探触子位置調節装置２２ａと、モータ駆動用制御アンプ３０と、位置合わせ制御アンプ３１と、制御器２４ａとから構成される。この様な構成を有する超音波探傷装置１７ａを用いて超音波探傷検査を行うには、先ず、上記外輪２を、図示しない搬送装置を用いて、上記液槽２９の底部に設けられた上記ワーク回転装置２１ａを構成する回転テーブル３２上に、中心軸を鉛直方向に配置した状態で載置する。そして、上記探触子１９ａを、上記探触子位置調節装置２２ａにより所定位置に移動させて、この探触子１９ａの先端部を、上記外輪２の内周面に形成された片側の外輪軌道１０（図４の上方位置の外輪軌道１０）に対向させる。尚、この様に、上記探触子１９ａの先端部を、この外輪軌道１０に対向させた状態で、この探触子１９ａに就いても、上記液槽２９内の白灯油に浸漬する。 The ultrasonic flaw detector 17a includes a liquid tank 29 storing white kerosene (including a rust preventive agent) as an ultrasonic transmission medium, a probe 19a, a flaw detector 20a, a work rotating device 21a, and a probe. The slave position adjusting device 22a, a motor driving control amplifier 30, a positioning control amplifier 31, and a controller 24a are included. In order to perform ultrasonic flaw detection using the ultrasonic flaw detector 17a having such a configuration, first, the outer ring 2 is moved to the workpiece provided on the bottom of the liquid tank 29 using a transport device (not shown). It mounts on the rotary table 32 which comprises the rotating apparatus 21a in the state which arrange | positioned the center axis | shaft in the perpendicular direction. Then, the probe 19a is moved to a predetermined position by the probe position adjusting device 22a, and the tip of the probe 19a is arranged on one side of the outer ring raceway formed on the inner peripheral surface of the outer ring 2. 10 (the outer ring raceway 10 in the upper position in FIG. 4). In this manner, the probe 19a is immersed in the white kerosene in the liquid tank 29 even when the probe 19a is in a state where the tip of the probe 19a is opposed to the outer ring raceway 10.

そして、上記制御器２４ａの指令に基づき、上記探傷器２０ａから上記探触子１９ａに所定の大きさの電圧を印加する（電圧信号を送信する）。これにより、この探触子１９ａから上記外輪軌道１０に向けて、上記電圧の大きさに応じた出力（出力レベル）の超音波を送波すると共に、エコー（反射波）をこの探触子１９ａにより受波し、このエコーを電圧信号に変換して、上記探傷器２０ａに送る。本例の場合には、この様な探傷作業を、上記外輪２を、上記ワーク回転装置２１ａにより一方向に所定速度で回転させつつ、上記探触子１９ａを、上記探触子位置調節装置２２ａにより上記外輪軌道１０の幅方向に回転又は揺動させながら行う。具体的には、上記探触子１９ａを、この外輪軌道１０との間に一定の間隔を保持した状態で、この外輪軌道１０の曲率に沿って回転又は揺動させる。 Based on a command from the controller 24a, a voltage having a predetermined magnitude is applied from the flaw detector 20a to the probe 19a (a voltage signal is transmitted). Thereby, an ultrasonic wave having an output (output level) corresponding to the magnitude of the voltage is transmitted from the probe 19a toward the outer ring raceway 10, and an echo (reflected wave) is transmitted to the probe 19a. Is received, converted into a voltage signal, and sent to the flaw detector 20a. In the case of this example, such a flaw detection operation is carried out by rotating the outer ring 2 in one direction at a predetermined speed by the work rotating device 21a, while moving the probe 19a to the probe position adjusting device 22a. This is performed while rotating or swinging in the width direction of the outer ring raceway 10. Specifically, the probe 19a is rotated or oscillated along the curvature of the outer ring raceway 10 in a state where a constant distance is maintained between the probe 19a and the outer ring raceway 10.

尚、上記ワーク回転装置２１ａは、モータ２５ｃにより回転駆動され、このモータ２５ｃは、上記モータ駆動用制御アンプ３０により制御される。又、上記探触子位置調節装置２２ａは、上記探触子１９ａのＸ方向及びＹ方向への移動を自在とする為の１組の並進移動機構と、この探触子１９ａのＺ方向への移動を自在とする為の昇降機構と、この探触子１９ａの揺動を自在とする為の揺動機構とを備え、これら各機構は、それぞれモータ２５ｄ〜２５ｇにより駆動される。又、これら各モータ２５ｄ〜２５ｇは、上記位置合わせ制御アンプ３１によりそれぞれ制御されており、この位置合わせ制御アンプ３１及び上記モータ駆動用制御アンプ３０は、前記制御器２４ａへの入力値により作動が制御されている。 The work rotating device 21a is rotationally driven by a motor 25c, and the motor 25c is controlled by the motor driving control amplifier 30. The probe position adjusting device 22a includes a pair of translational mechanisms for allowing the probe 19a to move in the X and Y directions, and the probe 19a in the Z direction. An elevating mechanism for allowing movement and an oscillating mechanism for allowing the probe 19a to freely oscillate are provided, and these mechanisms are driven by motors 25d to 25g, respectively. Each of the motors 25d to 25g is controlled by the alignment control amplifier 31, and the alignment control amplifier 31 and the motor drive control amplifier 30 are operated by an input value to the controller 24a. It is controlled.

上記探傷器２０ａでは、上記探触子１９ａに送信した電圧信号と、この探触子１９ａから受信した電圧信号とを基に、上記外輪軌道１０の表層部の欠陥の有無、及び、欠陥が存在する場合にはその大きさを計測する。そして、この探傷情報を上記制御器２４ａに送信し、この制御器２４ａに付属のディスプレイ等に表示する。 In the flaw detector 20a, based on the voltage signal transmitted to the probe 19a and the voltage signal received from the probe 19a, the presence or absence of a defect in the surface layer portion of the outer ring raceway 10 and the presence of the defect exist. If so, measure its size. The flaw detection information is transmitted to the controller 24a and displayed on a display attached to the controller 24a.

この様にして、本例の場合には、先ず、片側の外輪軌道１０の表層部に、平方根長さが１００μm 以上の欠陥が存在しない事が確認（保証）された外輪２を選出する。次いで、この様に選出された外輪２には、他側の外輪軌道１０の表層部を対象として超音波探傷検査を行う。これにより、この他側の外輪軌道１０の表層部に就いても、平方根長さが１００μm 以上の欠陥が存在しない事を確認された外輪２を、合格品として選出する。尚、この様な第三工程では、上記探触子１９ａとして、例えば、焦点型で、周波数が１０〜５０ＭHz、振動子径が３〜２０mmのものを使用できる。又、前記液槽２９内に貯留する超音波伝達媒体としては、白灯油以外にも、例えば前記第二工程の研削加工時に使用した研削液等を使用する事もできる。 Thus, in the case of this example, first, the outer ring 2 that is confirmed (guaranteed) that there is no defect having a square root length of 100 μm or more in the surface layer portion of the outer ring raceway 10 on one side is selected. Next, an ultrasonic flaw detection inspection is performed on the outer ring 2 selected in this manner with respect to the surface layer portion of the outer ring raceway 10 on the other side. Thus, the outer ring 2 that has been confirmed to have no defect having a square root length of 100 μm or more is selected as an acceptable product even in the surface layer portion of the outer ring raceway 10 on the other side. In such a third process, for example, the probe 19a having a focus type, a frequency of 10 to 50 MHz, and a vibrator diameter of 3 to 20 mm can be used. Further, as the ultrasonic transmission medium stored in the liquid tank 29, for example, the grinding fluid used at the time of the grinding process in the second step can be used in addition to the white kerosene.

以上の様に、上述した第三工程では、合否判定の基準となる欠陥の大きさを、前述した第一工程の場合に比べて小さくしている（第三工程：平方根長さ１００μm 、第一工程：平方根長さ２００μm ）。この為、本例の場合には、上記第三工程で行う超音波探傷検査を、上記第一工程で行う超音波探傷検査よりも高い精度で行うべく、探傷面に対する超音波の入射角の大きさ、及び、超音波の周波数の高さを、以下の様に規制している。 As described above, in the third process described above, the size of the defect serving as a criterion for the pass / fail judgment is made smaller than that in the first process described above (third process: square root length 100 μm, first Process: Square root length 200 μm). For this reason, in the case of this example, in order to perform the ultrasonic flaw inspection performed in the third step with higher accuracy than the ultrasonic flaw inspection performed in the first step, the incident angle of the ultrasonic wave with respect to the flaw detection surface is large. The height of the ultrasonic frequency is regulated as follows.

即ち、探傷面に対する入射角を大きくする程、より高い精度で欠陥の検出が可能になる為、上記第三工程で、前記探触子１９ａから前記外輪軌道１０に対して送波する超音波の、この外輪軌道１０の円周方向に関する入射角を、上記第一工程で、前記探触子１９から前記円柱状素材１６の外周面に対して送波する超音波の、この円柱状素材１６の外周面の円周方向に関する入射角よりも大きくしている。尚、本例の場合には、上記第三工程で、上記探触子１９ａから上記外輪軌道１０に対して送波する超音波の、この外輪軌道１０の円周方向に関する入射角を、屈折角が９０度に近い値になる様に設定している。 That is, since the defect can be detected with higher accuracy as the incident angle with respect to the flaw detection surface is increased, in the third step, the ultrasonic wave transmitted from the probe 19a to the outer ring raceway 10 can be detected. The incident angle of the outer ring raceway 10 in the circumferential direction is an ultrasonic wave transmitted from the probe 19 to the outer peripheral surface of the cylindrical material 16 in the first step. It is larger than the incident angle in the circumferential direction of the outer peripheral surface. In the case of this example, in the third step, the incident angle of the ultrasonic wave transmitted from the probe 19a to the outer ring raceway 10 with respect to the circumferential direction of the outer ring raceway 10 is defined as the refraction angle. Is set to a value close to 90 degrees.

更に、超音波の周波数を高くする程、より高い精度で欠陥の検出が可能になる為、上記第三工程で、上記探触子１９ａから上記外輪軌道１０に対して送波する超音波の周波数を、上記第一工程で、上記探触子１９から上記円柱状素材１６の外周面に対して送波する超音波の周波数よりも高くしている。尚、この様に、超音波の周波数を高くした場合には、減衰が大きくなる為、探傷深さが深くなると十分な検出精度を確保する事が難しくなる。但し、上記第三工程では、探傷深さの比較的浅い、上記外輪軌道１０の表層部を探傷範囲とする為、超音波の周波数を高くする事で、検出精度の向上を図れる。 Further, since the defect can be detected with higher accuracy as the frequency of the ultrasonic wave is increased, the frequency of the ultrasonic wave transmitted from the probe 19a to the outer ring raceway 10 in the third step. Is higher than the frequency of the ultrasonic wave transmitted from the probe 19 to the outer peripheral surface of the cylindrical material 16 in the first step. In this way, when the frequency of the ultrasonic wave is increased, the attenuation increases, so that it becomes difficult to ensure sufficient detection accuracy when the flaw detection depth is deep. However, in the third step, since the flaw detection depth is relatively shallow and the surface layer portion of the outer ring raceway 10 is in the flaw detection range, the detection accuracy can be improved by increasing the ultrasonic frequency.

一方、本例の場合には、上記第一工程で行う超音波探傷検査の精度を確保する為に、上記探触子１９に印加する電圧（探触子１９から円柱状素材１６の外周面に送波する超音波の出力）の大きさを、次の様に規制している。即ち、本例の場合には、上記第三工程の場合よりも上記第一工程の場合で、探傷深さが深くなる。この為、探触子に印加する電圧の値を、この第一工程と上記第三工程とで仮に同じ値とすると、超音波の減衰により、この第一工程で行う超音波探傷検査に就いて十分な精度を確保する事が難しくなる。この為、本例の場合には、上記第一工程で、上記探触子１９に前記探傷器２０から印加する電圧（探触子１９から円柱状素材１６の外周面に送波する超音波の出力）を、上記第三工程で、上記探触子１９ａに前記探触器２０ａから印加する電圧（探触子１９ａから外輪軌道１０に送波する超音波の出力）よりも高くしている。 On the other hand, in the case of this example, in order to ensure the accuracy of the ultrasonic flaw inspection performed in the first step, the voltage applied to the probe 19 (from the probe 19 to the outer peripheral surface of the columnar material 16). The size of the ultrasonic wave output) is regulated as follows. That is, in the case of this example, the flaw detection depth is deeper in the case of the first step than in the case of the third step. For this reason, assuming that the voltage applied to the probe is the same value in the first step and the third step, the ultrasonic inspection is performed in the first step due to attenuation of the ultrasonic wave. It becomes difficult to ensure sufficient accuracy. For this reason, in this example, in the first step, the voltage applied from the flaw detector 20 to the probe 19 (the ultrasonic wave transmitted from the probe 19 to the outer peripheral surface of the cylindrical material 16). Output) is set higher than the voltage applied to the probe 19a from the probe 20a in the third step (the output of the ultrasonic wave transmitted from the probe 19a to the outer ring orbit 10).

以上の様な本例の製造方法の場合には、前記車輪支持用転がり軸受ユニット１（図５参照）の内部空間１５に水が浸入した場合にも、上記各外輪軌道１０、１０にフレーキングが発生する事を有効に防止して長寿命化を図る事ができ、且つ、寿命のばらつきを抑えられる外輪２を、低コストで得られる。 In the case of the manufacturing method of the present example as described above, even when water enters the internal space 15 of the wheel support rolling bearing unit 1 (see FIG. 5), the outer ring raceways 10 and 10 are flaking. It is possible to effectively prevent the occurrence of the occurrence of the outer ring 2 and to extend the life, and to obtain the outer ring 2 that can suppress the variation in the life at low cost.

即ち、本例の場合には、素材として、非金属介在物の分布にばらつきを生じる、前記円柱状素材１６を使用し、前記第二工程で、この円柱状素材１６のうちで清浄度の高くなった部分から、上記各外輪軌道１０、１０の表層部を形成する。この為、上記第二工程の前後に行う、上記第一工程及び上記第三工程の超音波探傷検査を、前述した特許文献２に記載された製造方法（の第一工程及び第三工程）の場合に比べて、清浄度の高い部分を対象に（探傷範囲として）行う事ができる。この為、本例の様に、合否判定の基準となる欠陥の大きさを、上記第一工程及び上記第三工程でそれぞれ小さくした場合にも、上記特許文献２に記載された製造方法の場合に比べて、歩留りの低下を抑える事ができる。従って、本例の場合には、上記第三工程での合否判定の基準となる欠陥の大きさを、平方根長さで１００μm と、水を原因とするフレーキングの発生を十分に防止できる大きさとした場合にも、製造コストの上昇を十分に抑えられる。この結果、本例の場合には、水を原因とするフレーキングの発生を有効に防止できて、長寿命化を図れる外輪２を、低コストで得られる。 That is, in the case of this example, the columnar material 16 that causes variation in the distribution of non-metallic inclusions is used as a material, and in the second step, the degree of cleanliness is high among the columnar material 16. From the formed portion, the surface layer portion of each of the outer ring raceways 10 and 10 is formed. For this reason, the ultrasonic inspection of the first step and the third step performed before and after the second step is performed according to the manufacturing method (first step and third step) described in Patent Document 2 described above. Compared to the case, it is possible to carry out (as a flaw detection range) a portion with a high degree of cleanliness. For this reason, even in the case of the manufacturing method described in the above-mentioned Patent Document 2, even when the size of the defect serving as a criterion for pass / fail judgment is reduced in the first step and the third step, respectively, as in this example. Compared to the above, it is possible to suppress a decrease in yield. Therefore, in the case of this example, the size of the defect, which is a criterion for the pass / fail judgment in the third step, is 100 μm in terms of the square root length, which can sufficiently prevent the occurrence of flaking caused by water. In this case, the increase in manufacturing cost can be sufficiently suppressed. As a result, in the case of this example, it is possible to effectively prevent the occurrence of flaking due to water and to obtain the outer ring 2 that can extend the life at low cost.

又、本例の場合には、上述の様に、上記第二工程で、上記円柱状素材１６のうちで清浄度の高くなった部分（外周面からこの円柱状素材１６の外径寸法の３０％深さの範囲内に存在する部分）のみから、上記各外輪軌道１０、１０の表層部を形成する為、上記円柱状素材１６として、全体の清浄度がそれ程高くないものを使用できる。この為、材料コストの上昇を抑える事もできる。 In the case of this example, as described above, in the second step, the portion of the columnar material 16 having a high cleanliness (the outer diameter of the columnar material 16 from the outer peripheral surface is 30). Since the surface layer portion of each of the outer ring raceways 10 and 10 is formed only from the portion existing in the range of the% depth), the columnar material 16 can be used with a material whose overall cleanliness is not so high. For this reason, the increase in material cost can also be suppressed.

更に、本例の場合には、上記各外輪軌道１０、１０の表層部を、上記第一工程で清浄度の保証された部分から形成できるだけでなく、これら各外輪軌道１０、１０の表層部を対象として、上記第三工程で超音波探傷検査を行う。この為、本例の場合には、上記第二工程で、上記各外輪軌道１０、１０に傷や割れが生じたり、これら各外輪軌道１０、１０の表層部に、非金属介在物が出現した場合にも、この様な欠陥を有する外輪２を、不合格品として排除する事ができる。しかも、本例の場合には、この様な欠陥の検出を、超音波探傷検査により行う為、前述した漏洩磁束探傷検査では検出できない様な小さな欠陥の検出も可能になる。この為、本例の場合には、前述した特許文献３に記載された製造方法の場合に比べて、フレーキングの発生を安定して防止できて、寿命のばらつきを抑えられる外輪２を得られる。従って、本例の場合には、上記各外輪軌道１０、１０の表層部の清浄度に関して高い信頼性を確保できる安全性の高い外輪２を、製品として使用（提供）する事ができる。 Furthermore, in the case of this example, not only the surface layer portions of the outer ring raceways 10 and 10 can be formed from the portions where the cleanliness is guaranteed in the first step, but the surface layer portions of the outer ring raceways 10 and 10 are formed. As an object, ultrasonic flaw detection is performed in the third step. For this reason, in the case of this example, in the second step, the outer ring raceways 10 and 10 are scratched or cracked, or non-metallic inclusions appear in the surface layer portions of the outer ring raceways 10 and 10. Even in this case, the outer ring 2 having such a defect can be excluded as a rejected product. In addition, in the case of this example, such a defect is detected by ultrasonic flaw inspection, so that it is possible to detect a small defect that cannot be detected by the above-described leakage magnetic flux flaw inspection. For this reason, in the case of this example, compared to the manufacturing method described in Patent Document 3 described above, it is possible to stably prevent the occurrence of flaking and to obtain the outer ring 2 that can suppress the variation in life. . Therefore, in the case of this example, the highly safe outer ring 2 that can ensure high reliability with respect to the cleanliness of the surface layer portions of the outer ring raceways 10 and 10 can be used (provided) as a product.

又、本例の場合には、上記第一工程で、素材である円柱状素材１６に対して超音波探傷検査を行う為、上記第三工程の超音波探傷検査で、完成品である外輪２が不合格品となる割合を低くする事ができる。この為、歩留りの低下を抑え、製造コストの上昇を抑えられる。以下、この様な効果を得られる事を確認すべく、本発明者が行った実験内容及びその実験結果に就いて説明する。 In the case of this example, since the ultrasonic inspection is performed on the cylindrical material 16 that is the material in the first step, the outer ring 2 that is a finished product is obtained by the ultrasonic inspection in the third step. Can reduce the percentage of products that are rejected. For this reason, a decrease in yield can be suppressed and an increase in manufacturing cost can be suppressed. Hereinafter, in order to confirm that such an effect can be obtained, the contents of the experiment conducted by the present inventor and the result of the experiment will be described.

本実験では、前述した様な第一工程で、合格品として選出された円柱状素材１６から形成した外輪Ａ（本発明品）と、不合格品として排除された円柱状素材１６から形成した外輪Ｂ（比較品）とを、それぞれ５００個ずつ用意した。そして、上記外輪Ａ及び外輪Ｂに形成された外輪軌道１０、１０を対象として超音波探傷検査を行い、欠陥のエコー（Ｓ）の強度とノイズ（Ｎ）の強度との比（Ｓ／Ｎ）が３以上となる外輪の数、及び、その存在率を求めた。この様にして行った実験の結果を、以下の表１に示す。 In this experiment, in the first step as described above, the outer ring A formed from the columnar material 16 selected as an acceptable product (the product of the present invention) and the outer ring formed from the columnar material 16 excluded as a rejected product. 500 pieces of B (comparative product) were prepared. Then, an ultrasonic flaw detection inspection is performed on the outer ring raceways 10 and 10 formed on the outer ring A and the outer ring B, and a ratio (S / N) between the intensity of the defect echo (S) and the noise (N). The number of outer rings with a value of 3 or more and the existence ratio thereof were obtained. The results of experiments conducted in this way are shown in Table 1 below.

上記表１からも明らかな通り、上記第一工程で合格品として選出された円柱状素材１６から形成される外輪Ａの方が、不合格品となった円柱状素材１６から形成された外輪Ｂに比べて、上記各外輪軌道１０、１０の表層部に存在する欠陥の数及びその存在率が、著しく低くなる。従って、以上の様な実験により、前述した様な第一工程で、素材である上記円柱状素材１６に対して超音波探傷検査を行う事により、上記第三工程の超音波探傷検査で、完成品である外輪２が不合格品となる割合を低くする事ができて、歩留りの低下を図り、製造コストの上昇を抑える上で有効である事が確認できた。 As is clear from Table 1 above, the outer ring A formed from the columnar material 16 selected as an acceptable product in the first step is the outer ring B formed from the columnar material 16 that has been rejected. As compared with the above, the number of defects existing in the surface layer portions of the outer ring raceways 10 and 10 and the existence ratio thereof are remarkably lowered. Therefore, by the above-described experiment, the ultrasonic inspection is performed on the cylindrical material 16 that is the material in the first process as described above, thereby completing the ultrasonic inspection in the third process. It has been confirmed that the ratio of the outer ring 2 that is a product to be rejected can be reduced, the yield is reduced, and the production cost is suppressed.

上述した実施の形態に於いては、第三工程で行う超音波探傷検査の精度を確保すべく、超音波の入射角の大きさに関する条件、及び、超音波の周波数の高さに関する条件をそれぞれ満たし、且つ、第一工程で行う超音波探傷検査の精度を確保すべく、探触子に印加する電圧の大きさに関する条件を満たす事としている。但し、本発明を実施する場合には、上記の条件の全てを満たす必要はなく、少なくとも探触子に印加する電圧に関する条件を満たしていれば足り、超音波探傷検査の精度の向上を図る上で有効になる。 In the above-described embodiment, in order to ensure the accuracy of the ultrasonic flaw inspection performed in the third step, the condition regarding the size of the incident angle of the ultrasonic wave and the condition regarding the height of the frequency of the ultrasonic wave are respectively set. met, and, in order to ensure the ultrasonic accuracy of flaw detection performed in the first step, and with that satisfies the condition relating to the size of the voltage applied to the probe. However, when carrying out the present invention, it is not necessary to satisfy all of the above conditions , and it is sufficient that at least the conditions relating to the voltage applied to the probe are satisfied, so that the accuracy of ultrasonic flaw detection can be improved. It becomes effective with.

又、本発明の第一工程及び第三工程で行う超音波探傷検査に関して、合否判定の基準となる欠陥の大きさは、軌道部材の使用用途や使用条件、更には、この軌道部材の形状、素材となる円柱状素材の清浄度等を考慮して、適宜設定する事ができる。例えば、第三工程で行う超音波探傷検査の合否判定の基準となる欠陥の大きさは、平方根長さで１００μm と設定する以外にも、１２０μm 、１５０μm 、１８０μm と設定する事ができる。又、上記第一工程での合否判定の基準となる欠陥の大きさは、上記第三工程の超音波探傷検査で、完成品の軌道部材が不合格品となる割合を低くする観点から、この第三工程で基準とする欠陥の大きさよりも、僅かに大きい値とする事が好ましい。更に、複列の軌道面を有する軌道部材の場合には、この軌道部材の使用条件等に基づく、水の浸入し易さの相違を考慮して、合否判定の基準となる欠陥の大きさを、軌道面毎に変える事もできる。 In addition, regarding the ultrasonic flaw inspection performed in the first step and the third step of the present invention, the size of the defect that is a criterion for the pass / fail judgment is the use application and use conditions of the race member, and the shape of the race member, It can be set as appropriate in consideration of the cleanliness of the cylindrical material as the material. For example, the size of the defect, which is a criterion for the pass / fail judgment of the ultrasonic flaw inspection performed in the third step, can be set to 120 μm, 150 μm, and 180 μm in addition to the square root length of 100 μm. In addition, the size of the defect, which is a criterion for the pass / fail judgment in the first step, is determined from the viewpoint of reducing the rate at which the finished track member is rejected in the ultrasonic inspection of the third step. It is preferable to make the value slightly larger than the size of the defect used as a reference in the third step. Furthermore, in the case of a raceway member having a double-row raceway surface, considering the difference in the ease of water intrusion based on the use conditions of this raceway member, the size of the defect serving as a criterion for pass / fail judgment is set. It can also be changed for each track surface.

又、本発明の製造方法の対象となる軌道部材は、上述した実施の形態で説明した、車輪支持用転がり軸受ユニットを構成する外輪に限定されるものではないが、この外輪の様に、複列の外輪軌道を有し、取付部が一体に形成された軌道部材が、素材である円柱状素材を効率良く利用する面からは好ましい。但し、車輪支持用転がり軸受ユニットを構成するハブ（ハブ本体及び内輪）は勿論、スピンドルユニットを構成する外径側軌道部材及び内径側軌道部材、転がり軸受を構成する内輪及び外輪、ボールねじ装置を構成するねじ軸及びボールナット、リニアガイド装置を構成するレール及び移動体も、本発明の製造方法の対象となる。又、従動輪用の車輪支持用転がり軸受ユニットを構成する外径側軌道部材及び内径側軌道部材が、本発明の製造方法の対象となる事は勿論である。 In addition, the track member that is the object of the manufacturing method of the present invention is not limited to the outer ring that constitutes the wheel bearing rolling bearing unit described in the above-described embodiment. A track member having a row of outer ring raceways and integrally formed with a mounting portion is preferable from the viewpoint of efficiently using a cylindrical material as a material. However, not only the hub (hub body and inner ring) constituting the wheel support rolling bearing unit, but also the outer diameter side race member and inner diameter side race member constituting the spindle unit, the inner ring and outer ring constituting the rolling bearing, and the ball screw device. The screw shaft and ball nut that constitute the rail, the rail that constitutes the linear guide device, and the moving body are also objects of the manufacturing method of the present invention. Of course, the outer diameter side raceway member and the inner diameter side raceway member constituting the wheel bearing rolling bearing unit for the driven wheel are the targets of the manufacturing method of the present invention.

本発明の実施の形態の１例を示す、第一工程で円柱状素材に対し超音波探傷検査を行う状態を示す模式図。The schematic diagram which shows the state which performs an ultrasonic flaw inspection with respect to a columnar raw material at a 1st process which shows an example of embodiment of this invention. 同じく第一工程により選出された円柱状素材中に存在する、非金属介在物の分布状態を示す図。The figure which shows the distribution state of the nonmetallic inclusion which exists in the cylindrical raw material similarly selected by the 1st process. 同じく第二工程を工程順に説明する断面図。Sectional drawing which similarly demonstrates a 2nd process in order of a process. 同じく第三工程で外輪に対し超音波探傷検査を行う状態を示す模式図。The schematic diagram which shows the state which similarly performs an ultrasonic flaw inspection with respect to an outer ring | wheel at a 3rd process. 従来から知られた車輪支持用転がり軸受ユニットの１例を示す断面図。Sectional drawing which shows one example of the rolling bearing unit for wheel support conventionally known.

Explanation of symbols

１車輪支持用転がり軸受ユニット
２外輪
３取付部
４ハブ
５ハブ本体
６内輪
７スプライン孔
８取付フランジ
９かしめ部
１０外輪軌道
１１内輪軌道
１２転動体
１３保持器
１４ａ、１４ｂシール装置
１５内部空間
１６円柱状素材
１７、１７ａ超音波探傷装置
１８水槽
１９、１９ａ探触子
２０、２０ａ探触器
２１、２１ａワーク回転装置
２２、２２ａ探触子位置調節装置
２３、２３ａモータコントローラ
２４、２４ａ制御器
２５ａ〜２５ｇモータ
２６第一中間素材
２７第二中間素材
２８隔壁部
２９液槽
３０モータ駆動用制御アンプ
３１位置合わせ制御アンプ
３２回転テーブル DESCRIPTION OF SYMBOLS 1 Rolling bearing unit for wheel support 2 Outer ring 3 Mounting part 4 Hub 5 Hub main body 6 Inner ring 7 Spline hole 8 Mounting flange 9 Caulking part 10 Outer ring track 11 Inner ring track 12 Rolling element 13 Cage 14a, 14b Sealing device 15 Inner space 16 yen Columnar material 17, 17a Ultrasonic flaw detector 18 Water tank 19, 19a Probe 20, 20a Probe 21, 21a Work rotation device 22, 22a Probe position adjuster 23, 23a Motor controller 24, 24a Controller 25a- 25 g Motor 26 First intermediate material 27 Second intermediate material 28 Bulkhead 29 Liquid tank 30 Motor drive control amplifier 31 Positioning control amplifier 32 Rotary table

Claims

Both of the above-described rolling devices comprise a pair of raceway members each having a raceway surface facing each other and a plurality of rolling elements provided between the raceway surfaces so as to be freely rollable. A method of manufacturing a rolling member raceway member, wherein at least one raceway member of a raceway member is made of a metal cylindrical material,
By performing an ultrasonic flaw inspection on the columnar material, there is no defect of a predetermined size or more within the range of 30% of the outer diameter of the columnar material from the outer peripheral surface of the columnar material. The first step of selecting things,
By applying predetermined processing to the selected cylindrical material, the surface layer part of the raceway surface exists within the range of 30% of the outer diameter of this cylindrical material from the outer peripheral surface of this cylindrical material. A second step of obtaining a raceway member formed only from a portion to perform,
By performing an ultrasonic flaw inspection on the obtained track member, the surface layer portion of the track surface formed on the track member is provided with a third step of selecting a defect having a predetermined size or larger , and
Probe for transmitting ultrasonic waves in the ultrasonic inspection of the third step is applied to the probe for transmitting ultrasonic waves in the ultrasonic inspection of the first step. A method for manufacturing a rolling member raceway member, wherein the voltage is higher than a voltage applied to the rolling device.