JP5138259B2 - Hollow rack bar manufacturing method and hollow rack bar - Google Patents

Hollow rack bar manufacturing method and hollow rack bar Download PDF

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JP5138259B2
JP5138259B2 JP2007085678A JP2007085678A JP5138259B2 JP 5138259 B2 JP5138259 B2 JP 5138259B2 JP 2007085678 A JP2007085678 A JP 2007085678A JP 2007085678 A JP2007085678 A JP 2007085678A JP 5138259 B2 JP5138259 B2 JP 5138259B2
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shaft
temperature
tempering
tooth
rack bar
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JP2008240120A (en
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崇 山脇
哲之 村田
剛 山本
裕 清澤
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Neturen Co Ltd
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Neturen Co Ltd
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Priority to JP2007085678A priority Critical patent/JP5138259B2/en
Priority to AT08005032T priority patent/ATE455610T1/en
Priority to EP08005032A priority patent/EP1972395B1/en
Priority to DE602008000555T priority patent/DE602008000555D1/en
Priority to US12/051,996 priority patent/US8104369B2/en
Priority to CN200810085186XA priority patent/CN101269394B/en
Priority to CN201110080424.XA priority patent/CN102225508B/en
Publication of JP2008240120A publication Critical patent/JP2008240120A/en
Priority to US13/347,482 priority patent/US8595936B2/en
Priority to US13/347,486 priority patent/US8499660B2/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

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Description

本発明は、自動車のパワーステアリング装置等に使用されるラック＆ピニオンギアに用いられる中空ラックバーの製造方法及び中空ラックバーに関し、特にネジ部が形成された端部の強化を図ることができるものに関する。   The present invention relates to a method for manufacturing a hollow rack bar used for a rack and pinion gear used in a power steering device of an automobile and the like, and particularly to a hollow rack bar that can reinforce an end portion on which a screw portion is formed. About.

自動車のパワーステアリング装置に使用される中実ラックバーは、中間部にピニオンギアに噛み合わされる歯部を有するとともに、その端部にボールジョイントとの接続に供されるネジ部が形成されている。   A solid rack bar used in a power steering device of an automobile has a tooth portion meshed with a pinion gear at an intermediate portion, and a screw portion used for connection with a ball joint is formed at an end portion thereof. .

中実ラックバーは、例えば、Ｓ４５Ｃ等の調質材からなる中実材から形成されている。Ｓ４５Ｃは素材硬度がＨｖ２４０〜２８５であるが、中間部に位置する軸部については切削加工にて歯部を形成した後、熱処理を行うことで硬度をＨｖ６００以上としている。これに対し、端部に位置するネジ部は加工を行うため、素材硬度が維持されている。   The solid rack bar is formed from a solid material made of a tempered material such as S45C, for example. In S45C, the material hardness is Hv 240 to 285, but the shaft portion located in the middle portion is formed with teeth by cutting and then heat-treated, so that the hardness is Hv 600 or more. On the other hand, since the screw portion located at the end is processed, the material hardness is maintained.

図２１は中実ラックバーに代わり近年開発された中空ラックバーの一例を示す図である。中空ラックバー１００は、中空の軸部１０１を有し、この軸部１０１の中間部には、ピニオン（不図示）に噛み合わされる歯部１０２が形成されているとともに、その端部１０３にはボールジョイントとの接続に供される内周ネジ１０４とが設けられている。なお、図２１中１１０はボールジョイント、１１１はボールジョイント１１０を外周ネジ１１２を介して端部１０３に接続するためのソケットを示している。   FIG. 21 is a view showing an example of a hollow rack bar developed in recent years in place of the solid rack bar. The hollow rack bar 100 has a hollow shaft portion 101, and a tooth portion 102 that is engaged with a pinion (not shown) is formed at an intermediate portion of the shaft portion 101. An inner peripheral screw 104 used for connection with the ball joint is provided. In FIG. 21, reference numeral 110 denotes a ball joint, and 111 denotes a socket for connecting the ball joint 110 to the end portion 103 via an outer peripheral screw 112.

なお、中空ラックバーを高周波加熱する技術、部分的に熱処理条件を変える技術は一般に知られている（特許文献１，２参照）。
特開昭６３−２９７５２４号公報 特開平６−２６４１４７号公報 In addition, the technique of high-frequency heating the hollow rack bar and the technique of partially changing the heat treatment conditions are generally known (see Patent Documents 1 and 2).
JP-A 63-297524 JP-A-6-264147

上述した中空ラックバーにあっては、次のような問題があった。すなわち、最近自動車の大型化でタイヤからラック＆ピニオンギアへの入力荷重が大きくなる傾向がある。しかしながら、軸部１０１は熱処理により硬度を高めることができるが、端部１０３はネジ加工を行うため硬度を高めることができない。このため、タイヤ側に配置されたボールジョイント１１０から荷重を入力する強度テスト（図２１中矢印Ｋ）を行うと端部１０３や内周ネジの強度不足からネジが緩んだり、図２２に示すようにボールジョイント１１０が抜け落ちてしまうことがあった。   The hollow rack bar described above has the following problems. That is, the input load from the tire to the rack and pinion gear tends to increase due to the recent increase in size of automobiles. However, although the shaft portion 101 can be increased in hardness by heat treatment, the end portion 103 cannot be increased in hardness because it is threaded. Therefore, when a strength test (arrow K in FIG. 21) for inputting a load from the ball joint 110 arranged on the tire side is performed, the screws loosen due to insufficient strength of the end portion 103 or the inner peripheral screw, or as shown in FIG. In some cases, the ball joint 110 may fall off.

そこで本発明は、端部に形成された内周ネジの加工精度の維持及び遅れ破壊の防止を行いつつ、端部の強度を増大させる中空ラックバーの製造方法及び中空ラックバーを提供することを目的としている。   Therefore, the present invention provides a method for manufacturing a hollow rack bar and a hollow rack bar that increase the strength of the end while maintaining the machining accuracy of the inner peripheral screw formed at the end and preventing delayed fracture. It is aimed.

前記課題を解決し目的を達成するために、本発明の中空ラックバーの製造方法及び中空ラックバーは次のように構成されている。   In order to solve the above-described problems and achieve the object, the method for manufacturing a hollow rack bar and the hollow rack bar of the present invention are configured as follows.

ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、前記軸部に歯部を形成する歯部形成工程と、前記端部に高周波焼入れを行う端部焼入れ工程と、前記端部に第１の温度による高周波焼戻しを行う第１温度端部焼戻し工程と、この第１温度端部焼戻し工程後に前記端部の内周に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、前記歯部に高周波焼入れを行う歯部焼入れ工程と、前記軸部に高周波焼入れを行う軸部焼入れ工程と、前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする。 In the method of manufacturing a hollow rack bar having a tooth portion meshed with a pinion gear in the shaft portion and a screw portion provided for connection to a ball joint on the inner peripheral surface of the end portion, the shaft portion includes A tooth part forming step for forming a tooth part, an end quenching step for induction hardening at the end, a first temperature end tempering step for induction tempering at a first temperature at the end, and the first After the temperature end tempering step, a screw processing step for performing screw processing for forming the screw portion on the inner periphery of the end portion, a tooth portion quenching step for induction hardening the tooth portion, and an induction hardening for the shaft portion And a second temperature tempering step of performing induction tempering at a second temperature lower than the first temperature on the end portion, the tooth portion, and the shaft portion. To do.

ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、前記軸部に歯部を形成する歯部形成工程と、前記端部外周面に高周波焼入れを行う端部焼入れ工程と、前記端部外周面に第１の温度による高周波焼戻しを行う第１温度焼戻し工程と、この第１温度焼戻し工程後に前記端部の内周に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、前記歯部に高周波焼入れを行う歯部焼入れ工程と、前記軸部に高周波焼入れを行う軸部焼入れ工程と、前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする。 And has a toothing which meshes with the pinion gear on the shaft portion, the hollow rack manufacturing method for Rene di unit is subjected to a connection of the ball joint is formed on the inner peripheral surface of the end portion, the shaft portion A tooth portion forming step for forming a tooth portion, an end quenching step for induction hardening on the outer peripheral surface of the end portion, a first temperature tempering step for induction tempering at a first temperature on the outer peripheral surface of the end portion, After the first temperature tempering step, a screw processing step for performing screw processing for forming the screw portion on the inner periphery of the end portion, a tooth portion quenching step for performing induction hardening on the tooth portion, and a high frequency on the shaft portion. A shaft portion quenching step for performing quenching, and a second temperature tempering step for subjecting the end portion, the tooth portion, and the shaft portion to induction tempering at a second temperature lower than the first temperature are provided. And

ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、前記軸部に歯部を形成する歯部形成工程と、前記端部の内周に開口側からヌスミ加工を行って凹部を形成するヌスミ加工工程と、前記端部の内周であって前記凹部より奥側に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、前記端部の開口端に高周波焼入れを行う端部焼入れ工程と、前記歯部に高周波焼入れを行う歯部焼入れ工程と、前記端部に第１の温度による高周波焼戻しを行う第１温度焼戻し工程と、前記軸部に高周波焼入れを行う軸部焼入れ工程と、前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする。 And has a toothing which meshes with the pinion gear on the shaft portion, the hollow rack manufacturing method for Rene di unit is subjected to a connection of the ball joint is formed on the inner peripheral surface of the end portion, the shaft portion A tooth forming step for forming a tooth portion on the inner periphery, a step for forming a recess on the inner periphery of the end portion from the opening side by forming a recess, and an inner periphery of the end portion that is behind the recess A screw processing step for performing screw processing to form the screw portion, an end quenching step for induction hardening at the opening end of the end portion, a tooth quenching step for induction hardening to the tooth portion, A first temperature tempering step in which induction tempering is performed on the end portion by a first temperature; a shaft portion quenching step in which induction hardening is performed on the shaft portion; and the first temperature on the end portion, the tooth portion, and the shaft portion. Induction tempering with lower second temperature Characterized in that a second temperature tempering step of performing.

ピニオンギアに噛み合わされる歯部が形成された中空状の軸部と、この軸部と同じ材料で形成され、前記軸部の少なくとも一方の端の内周面に設けられ、ボールジョイントとの接続に供されるネジ部が形成された端部とを備え、前記軸部の硬度は、前記端部の硬度より高く形成されていることを特徴とする。 A shaft portion empty shape in which teeth are formed to be engaged with the pinion gear, which is formed of the same material as the shaft portion, provided on the inner peripheral surface of at least one end of the shaft portion, the ball joint And an end portion on which a screw portion provided for connection is formed, and the shaft portion has a hardness higher than that of the end portion.

本発明によれば、端部に形成されたネジ部の加工精度の維持及び遅れ破壊の防止を行いつつ、端部の強度を増大させることが可能となる。   According to the present invention, it is possible to increase the strength of the end portion while maintaining the machining accuracy of the screw portion formed at the end portion and preventing delayed fracture.

図１は本発明の一実施の形態に係る中空ラックバー１０が組み込まれたラック＆ピニオンギアの要部を示す縦断面図である。中空ラックバー１０は、管状の軸部１１を有し、この軸部１１の中間部には、ピニオン３０に噛み合わされる歯部１２が形成されているとともに、両端に位置する歯側端部１３，軸側端部１４の内周面にはボールジョイントとの接続に供されるネジ１５とが設けられている。中空ラックバー１０は、例えばＳＭｎ４３３等の材料を用い、当初の硬度はＨｖ１５５〜２００である。   FIG. 1 is a longitudinal sectional view showing a main part of a rack and pinion gear in which a hollow rack bar 10 according to an embodiment of the present invention is incorporated. The hollow rack bar 10 has a tubular shaft portion 11, and a tooth portion 12 meshed with the pinion 30 is formed at an intermediate portion of the shaft portion 11, and a tooth side end portion 13 positioned at both ends. A screw 15 provided for connection to the ball joint is provided on the inner peripheral surface of the shaft end 14. The hollow rack bar 10 is made of a material such as SMn433, and has an initial hardness of Hv155 to 200.

一方、歯側端部１３側には、ソケット２１を介してボールジョイント２０が取り付けられている。ソケット２１には、ネジ１５に螺合する外周ネジ２２とが設けられている。また、ソケット２１は、ボールジョイント２０を揺動自在に支持する構造となっており、樹脂シート２３が配置されている。なお、図１中４０はケーシング、５０は蛇腹式のブーツを示している。   On the other hand, a ball joint 20 is attached to the tooth side end portion 13 via a socket 21. The socket 21 is provided with an outer peripheral screw 22 that is screwed onto the screw 15. The socket 21 has a structure that supports the ball joint 20 in a swingable manner, and is provided with a resin sheet 23. In FIG. 1, reference numeral 40 denotes a casing, and 50 denotes a bellows type boot.

上述した中空ラックバー１０は、次のようにして形成される。すなわち、軸部１１に冷間の転写鍛造にて歯部１２を形成する。具体的には、パイプ材を冷間鍛造金型によって加圧することにより歯形一次成形と共に上面が平坦に形成され、次なる工程でパイプ材の空洞に芯金が圧入される。芯金は棒状に形成されるとともに、パイプ材の平坦部側にテーパ状の突起部を有しており、突起部がパイプ材の平坦部に内周側において係合することにより平坦部の肉が成形型の歯列に向けて塑性変形的に流動することにより張出され、パイプ材の外周平坦部に成形型の歯列に対応した形状の直線方向の歯部１２が転写方式にて付与される。   The hollow rack bar 10 described above is formed as follows. That is, the tooth portion 12 is formed on the shaft portion 11 by cold transfer forging. Specifically, by pressing the pipe material with a cold forging die, the upper surface is formed flat together with the tooth profile primary molding, and the core metal is press-fitted into the cavity of the pipe material in the next step. The cored bar is formed in a rod shape, and has a tapered projection on the flat portion side of the pipe material, and the projection portion engages with the flat portion of the pipe material on the inner peripheral side, so that the meat of the flat portion is Is projected by plastic deformation toward the teeth of the mold, and linear teeth 12 having a shape corresponding to the teeth of the mold are applied to the outer peripheral flat portion of the pipe material by the transfer method. Is done.

次に、中空ラックバー１０の硬度上昇及び歯側端部１３、軸側端部１４へのネジ形成を行う。硬度上昇及びネジ形成には、例えば以下の３つの処理方法がある。   Next, the hardness of the hollow rack bar 10 is increased, and screws are formed on the tooth side end portion 13 and the shaft side end portion 14. For example, there are the following three processing methods for increasing the hardness and forming the screw.

第１の処理方法は、以下のように行う。すなわち、図３Ａ及び図３Ｂに示すように、歯部１２が形成された歯側端部１３に例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させる（端部焼入れ工程）。次に、歯側端部１３に６００℃（第１の温度）による高周波焼戻しを行い（第１温度焼戻し工程）、硬度を例えばＨｖ２５０〜４５０とする。同様に図４Ａ及び図４Ｂに示すように、軸側端部１４に高周波焼入れ・高周波焼戻しを行い、硬度をＨｖ２５０〜４５０とする。   The first processing method is performed as follows. That is, as shown in FIGS. 3A and 3B, the tooth side end portion 13 on which the tooth portion 12 is formed is subjected to induction hardening at, for example, 1000 ° C. to increase the hardness to Hv 620 (end hardening step). Next, induction tempering at 600 ° C. (first temperature) is performed on the tooth side end portion 13 (first temperature tempering step), and the hardness is set to, for example, Hv 250 to 450. Similarly, as shown in FIGS. 4A and 4B, induction hardening and induction tempering are performed on the shaft side end portion 14 to set the hardness to Hv 250 to 450.

次に、図５に示すように、歯側端部１３及び軸側端部１４の内周にネジ１５を形成するためのネジ加工を行う（ネジ加工工程）。   Next, as shown in FIG. 5, screw processing for forming the screw 15 on the inner periphery of the tooth side end portion 13 and the shaft side end portion 14 is performed (screw processing step).

次に、図６Ａに示すように、歯部１２に例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させ、同様に図６Ｂに示すように、軸側端部１４側の軸部１１に高周波焼入れを行い、Ｈｖ６２０に上昇させる（軸部焼入れ工程）。次に、図７に示すように、中空ラックバー１０全体を２００℃（第２の温度）による高周波焼戻しを行う（第２温度焼戻し工程）。   Next, as shown in FIG. 6A, the tooth portion 12 is induction-hardened at 1000 ° C., for example, to increase the hardness to Hv 620, and similarly to the shaft portion 11 on the shaft side end portion 14 side as shown in FIG. 6B. Induction hardening is performed to raise the Hv620 (shaft hardening process). Next, as shown in FIG. 7, the entire hollow rack bar 10 is subjected to induction tempering at 200 ° C. (second temperature) (second temperature tempering step).

これにより、第１の処理方法においては、図８に示すような硬度状態となる。すなわち、軸部１１ａ，１１ｂの硬度はＨｖ４５０〜６５０、歯側端部１３の硬度はＨｖ２５０〜４５０となる。したがって、歯側端部１３の外力に対する強度を高めると同時にネジ１５における加工精度の維持及び遅れ破壊の防止を図ることができる。   Thereby, in the 1st processing method, it will be in a hardness state as shown in FIG. That is, the hardness of the shaft portions 11a and 11b is Hv450 to 650, and the hardness of the tooth side end portion 13 is Hv250 to 450. Therefore, it is possible to increase the strength of the tooth side end portion 13 against the external force and at the same time maintain the machining accuracy of the screw 15 and prevent delayed fracture.

第２の処理方法は、以下のように行う。すなわち、図９Ａ及び図９Ｂに示すように、歯部１２が形成された歯側端部１３の外周面１３ａの深さｔ１（０．５〜１ｍｍ程度）に、例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させる（端部焼入れ工程）。次に、歯側端部１３の外周面１３ａに６００℃（第１の温度）による高周波焼戻しを行い（第１温度焼戻し工程）、硬度を例えばＨｖ２５０〜４５０とする。同様に図１０Ａ及び図１０Ｂに示すように、軸側端部１４の外周面１４ａに高周波焼入れ・高周波焼戻しを行い、硬度をＨｖ２５０〜４５０とする。
The second processing method is performed as follows. That is, as shown in FIGS. 9A and 9B, induction hardening at, for example, 1000 ° C. is performed at a depth t1 (about 0.5 to 1 mm) of the outer peripheral surface 13a of the tooth side end portion 13 where the tooth portion 12 is formed. The hardness is increased to Hv620 (end quenching process). Next, induction tempering at 600 ° C. (first temperature) is performed on the outer peripheral surface 13a of the tooth side end portion 13 (first temperature tempering step), and the hardness is set to, for example, H v2 50 to 450. Similarly, as shown in FIGS. 10A and 10B, induction hardening and induction tempering are performed on the outer peripheral surface 14 a of the shaft side end portion 14, and the hardness is set to H v2 50-450.

次に、図１１に示すように、歯側端部１３及び軸側端部１４の内周にネジ１５を形成するためのネジ加工を行う（ネジ加工工程）。   Next, as shown in FIG. 11, screw processing for forming the screw 15 on the inner periphery of the tooth side end portion 13 and the shaft side end portion 14 is performed (screw processing step).

次に、図１２Ａに示すように、歯部１２に例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させ、同様に図１２Ｂに示すように、軸側端部１４側の軸部１１に高周波焼入れを行い、Ｈｖ６２０に上昇させる（軸部焼入れ工程）。次に、図１３に示すように、中空ラックバー１０全体を２００℃（第２の温度）による高周波焼戻しを行う（第２温度焼戻し工程）。   Next, as shown in FIG. 12A, the tooth portion 12 is induction-hardened at 1000 ° C., for example, to increase the hardness to Hv620, and similarly to the shaft portion 11 on the shaft side end portion 14 side as shown in FIG. 12B. Induction hardening is performed to raise the Hv620 (shaft hardening process). Next, as shown in FIG. 13, the entire hollow rack bar 10 is subjected to induction tempering at 200 ° C. (second temperature) (second temperature tempering step).

これにより、第２の処理方法においては、図１４に示すような硬度状態となる。すなわち、軸部１１の硬度はＨｖ４５０〜６５０、歯側端部１３の硬度はＨｖ２５０〜４５０となる。したがって、歯側端部１３の外力に対する強度を高めると同時にネジ１５における加工精度の維持及び遅れ破壊の防止を図ることができる。   Thereby, in the 2nd processing method, it will be in a hardness state as shown in FIG. That is, the hardness of the shaft portion 11 is Hv450 to 650, and the hardness of the tooth side end portion 13 is Hv250 to 450. Therefore, it is possible to increase the strength of the tooth side end portion 13 against the external force and at the same time maintain the machining accuracy of the screw 15 and prevent delayed fracture.

第３の処理方法は、以下のように行う。すなわち、歯側端部１３及び軸側端部１４の内周に開口側からヌスミ加工を行い、奥行き５ｍｍ程度の凹部１６を形成する（ヌスミ加工工程）。次に、歯側端部１３の内周に凹部１６の奥側へネジ１５を形成するためのネジ加工を行う（ネジ加工工程）。次に、図１６Ａ及び図１６Ｂに示すように、歯部１２が形成された歯側端部１３の開口端１３ｂから奥行きｔ２（５ｍｍ以内）に例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させる（端部焼入れ工程）。次に、歯側端部１３の開口端１３ｂに６００℃（第１の温度）による高周波焼戻しを行い（第１温度焼戻し工程）、硬度を例えばＨｖ２５０〜４５０とする。同様に図１７Ａ及び図１７Ｂに示すように、軸側端部１４の開口端１４ｂに高周波焼入れ・高周波焼戻しを行い、硬度をＨｖ２５０〜４５０とする。この熱処理工程においては、凹部１６が設けられているため、ネジ１５には熱が伝わらず加工精度は維持される。   The third processing method is performed as follows. In other words, the inside of the tooth side end portion 13 and the shaft side end portion 14 is crushed from the opening side to form the concave portion 16 having a depth of about 5 mm (the punishment step). Next, screw processing for forming the screw 15 on the inner side of the tooth side end portion 13 on the back side of the recess 16 is performed (screw processing step). Next, as shown in FIGS. 16A and 16B, induction hardening at 1000 ° C., for example, is performed at a depth t2 (within 5 mm) from the opening end 13b of the tooth side end portion 13 where the tooth portion 12 is formed, and the hardness is set to Hv620. Raise (end quenching process). Next, induction tempering at 600 ° C. (first temperature) is performed on the opening end 13b of the tooth side end portion 13 (first temperature tempering step), and the hardness is set to, for example, Hv 250 to 450. Similarly, as shown in FIGS. 17A and 17B, induction hardening and induction tempering are performed on the opening end 14 b of the shaft side end portion 14 so that the hardness is Hv 250 to 450. In this heat treatment step, since the recess 16 is provided, heat is not transmitted to the screw 15 and the machining accuracy is maintained.

次に、図１８Ａに示すように、歯部１２に例えば１０００℃の高周波焼入れを行い、硬度をＨｖ６２０に上昇させ、同様に図１８Ｂに示すように、軸側端部１４側の軸部１１に高周波焼入れを行い、Ｈｖ６２０に上昇させる（軸部焼入れ工程）。次に、図１９に示すように、中空ラックバー１０全体を２００℃（第２の温度）による高周波焼戻しを行う（第２温度焼戻し工程）。   Next, as shown in FIG. 18A, the tooth portion 12 is induction-hardened at, for example, 1000 ° C. to increase the hardness to Hv 620, and similarly to the shaft portion 11 on the shaft side end portion 14 side as shown in FIG. 18B. Induction hardening is performed to raise the Hv620 (shaft hardening process). Next, as shown in FIG. 19, the entire hollow rack bar 10 is subjected to induction tempering at 200 ° C. (second temperature) (second temperature tempering step).

これにより、第３の処理方法においては、図２０に示すような硬度状態となる。すなわち、軸側端部１４側の軸部１１及び歯部１２の硬度はＨｖ４５０〜６５０、歯側端部１３の開口端１３ｂの硬度はＨｖ２５０〜４５０となる。したがって、歯側端部１３の外力に対する強度を高めると同時にネジ１５における加工精度の維持及び遅れ破壊の防止を図ることができる。   Thereby, in the 3rd processing method, it will be in a hardness state as shown in FIG. That is, the hardness of the shaft portion 11 and the tooth portion 12 on the shaft side end portion 14 side is Hv 450 to 650, and the hardness of the opening end 13b of the tooth side end portion 13 is Hv 250 to 450. Therefore, it is possible to increase the strength of the tooth side end portion 13 against the external force and at the same time maintain the machining accuracy of the screw 15 and prevent delayed fracture.

上述したように本発明の実施の形態に係る中空ラックバーの製造方法によれば、歯側端部１３及び軸側端部１４に形成されたネジ１５の加工精度の維持及び遅れ破壊の防止を行いつつ、歯側端部１３の強度を増大させることができる。   As described above, according to the method for manufacturing a hollow rack bar according to the embodiment of the present invention, it is possible to maintain the machining accuracy of the screw 15 formed on the tooth side end portion 13 and the shaft side end portion 14 and prevent delayed fracture. While performing, the intensity | strength of the tooth side edge part 13 can be increased.

なお、本発明は前記実施の形態に限定されるものではない。例えば、中空ラックバー１０の素材はＳｍｎ４３３に限られず他の材料を用いてもよい。また、熱処理条件（焼入れ温度・焼戻し温度）は、所望の硬度を得るために設定されており、材質・形状等で決められるので、本実施例での温度だけに限られるものではない。この他、本発明の要旨を逸脱しない範囲で種々変形実施可能であるのは勿論である。   The present invention is not limited to the above embodiment. For example, the material of the hollow rack bar 10 is not limited to Smn433, and other materials may be used. The heat treatment conditions (quenching temperature and tempering temperature) are set to obtain a desired hardness and are determined by the material, shape, etc., and are not limited to the temperature in this embodiment. Of course, various modifications can be made without departing from the scope of the present invention.

本発明の一実施の形態に係る中空ラックバーが組み込まれたラック＆ピニオンギアの要部を示す縦断面図。The longitudinal cross-sectional view which shows the principal part of the rack & pinion gear in which the hollow rack bar which concerns on one embodiment of this invention was integrated. 同中空ラックバーの要部を示す縦断面図。The longitudinal cross-sectional view which shows the principal part of the same hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (induction hardening) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial side edge part of the same hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the axial side edge part of the hollow rack bar. 同中空ラックバーの歯側端部及び軸側端部のネジ加工工程を示す縦断面図。The longitudinal cross-sectional view which shows the threading process of the tooth side edge part and axial side edge part of the same hollow rack bar. 同中空ラックバーの歯部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the tooth | gear part of the hollow rack bar. 同中空ラックバーの軸部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial part of the same hollow rack bar. 同中空ラックバーの熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the same hollow rack bar. 同中空ラックバーの硬度を示す縦断面図。The longitudinal cross-sectional view which shows the hardness of the same hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (induction hardening) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial side edge part of the same hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the axial side edge part of the hollow rack bar. 同中空ラックバーの歯側端部及び軸側端部のネジ加工工程を示す縦断面図。The longitudinal cross-sectional view which shows the threading process of the tooth side edge part and axial side edge part of the same hollow rack bar. 同中空ラックバーの歯部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the tooth | gear part of the hollow rack bar. 同中空ラックバーの軸部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial part of the same hollow rack bar. 同中空ラックバーの熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the same hollow rack bar. 同中空ラックバーの硬度を示す縦断面図。The longitudinal cross-sectional view which shows the hardness of the same hollow rack bar. 同中空ラックバーの歯側端部及び軸側端部のネジ加工工程を示す縦断面図。The longitudinal cross-sectional view which shows the threading process of the tooth side edge part and axial side edge part of the same hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (induction hardening) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの歯側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the tooth side edge part of the hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial side edge part of the same hollow rack bar. 同中空ラックバーの軸側端部の熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the axial side edge part of the hollow rack bar. 同中空ラックバーの歯部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the tooth | gear part of the hollow rack bar. 同中空ラックバーの軸部の熱処理工程（高周波焼入れ）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency hardening) of the axial part of the same hollow rack bar. 同中空ラックバーの熱処理工程（高周波焼戻し）を示す縦断面図。The longitudinal cross-sectional view which shows the heat processing process (high frequency tempering) of the same hollow rack bar. 同中空ラックバーの硬度を示す縦断面図。The longitudinal cross-sectional view which shows the hardness of the same hollow rack bar. 従来の中空ラックバーとボールジョイントを示す側面図。The side view which shows the conventional hollow rack bar and a ball joint. 従来の中空ラックバーとボールジョイントの問題点を示す側面図。The side view which shows the problem of the conventional hollow rack bar and a ball joint.

符号の説明Explanation of symbols

１０…中空ラックバー、１１…軸部、１２…歯部、１３…歯側端部、１４…軸側端部、１５…ネジ、１６…凹部。   DESCRIPTION OF SYMBOLS 10 ... Hollow rack bar, 11 ... Shaft part, 12 ... Tooth part, 13 ... Tooth side edge part, 14 ... Shaft side edge part, 15 ... Screw, 16 ... Recessed part

Claims (4)

ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、
前記軸部に歯部を形成する歯部形成工程と、
前記端部に高周波焼入れを行う端部焼入れ工程と、
前記端部に第１の温度による高周波焼戻しを行う第１温度端部焼戻し工程と、
この第１温度端部焼戻し工程後に前記端部の内周に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、
前記歯部に高周波焼入れを行う歯部焼入れ工程と、
前記軸部に高周波焼入れを行う軸部焼入れ工程と、
前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする中空ラックバーの製造方法。 In the manufacturing method of the hollow rack bar having a tooth portion meshed with the pinion gear in the shaft portion, and a screw portion provided for connection to the ball joint on the inner peripheral surface of the end portion thereof,
A tooth part forming step of forming a tooth part on the shaft part;
An end quenching step of induction hardening to the end;
A first temperature end tempering step for performing induction tempering at a first temperature on the end;
A screw processing step for performing screw processing for forming the screw portion on the inner periphery of the end after the first temperature end tempering step;
Tooth part quenching step of induction hardening to the tooth part;
A shaft quenching step of induction hardening the shaft,
A method of manufacturing a hollow rack bar, comprising: a second temperature tempering step of performing induction tempering on the end portion, the tooth portion, and the shaft portion by a second temperature lower than the first temperature. ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、
前記軸部に歯部を形成する歯部形成工程と、
前記端部外周面に高周波焼入れを行う端部焼入れ工程と、
前記端部外周面に第１の温度による高周波焼戻しを行う第１温度焼戻し工程と、
この第１温度焼戻し工程後に前記端部の内周に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、
前記歯部に高周波焼入れを行う歯部焼入れ工程と、
前記軸部に高周波焼入れを行う軸部焼入れ工程と、
前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする中空ラックバーの製造方法。 And has a toothing which meshes with the pinion gear on the shaft portion, the hollow rack manufacturing method for Rene di unit is subjected to a connection of the ball joint is formed on the inner peripheral surface of the end portion,
A tooth part forming step of forming a tooth part on the shaft part;
An end quenching step of induction hardening the outer peripheral surface of the end;
A first temperature tempering step of performing induction tempering on the outer peripheral surface of the end portion at a first temperature;
A screw processing step for performing screw processing for forming the screw portion on the inner periphery of the end portion after the first temperature tempering step;
Tooth part quenching step of induction hardening to the tooth part;
A shaft quenching step of induction hardening the shaft,
A method of manufacturing a hollow rack bar, comprising: a second temperature tempering step of performing induction tempering on the end portion, the tooth portion, and the shaft portion by a second temperature lower than the first temperature. ピニオンギアに噛み合わされる歯部を軸部に有するとともに、その端部の内周面にボールジョイントとの接続に供されるネジ部が形成された中空ラックバーの製造方法において、
前記軸部に歯部を形成する歯部形成工程と、
前記端部の内周に開口側からヌスミ加工を行って凹部を形成するヌスミ加工工程と、
前記端部の内周であって前記凹部より奥側に前記ネジ部を形成するためのネジ加工を行うネジ加工工程と、
前記端部の開口端に高周波焼入れを行う端部焼入れ工程と、
前記歯部に高周波焼入れを行う歯部焼入れ工程と、
前記端部に第１の温度による高周波焼戻しを行う第１温度焼戻し工程と、
前記軸部に高周波焼入れを行う軸部焼入れ工程と、
前記端部、前記歯部及び前記軸部に前記第１の温度より低い第２の温度による高周波焼戻しを行う第２温度焼戻し工程とを備えていることを特徴とする中空ラックバーの製造方法。 And has a toothing which meshes with the pinion gear on the shaft portion, the hollow rack manufacturing method for Rene di unit is subjected to a connection of the ball joint is formed on the inner peripheral surface of the end portion,
A tooth part forming step of forming a tooth part on the shaft part;
A step of forming a recess by carrying out a process from the opening side on the inner periphery of the end part; and
A screw processing step for performing screw processing for forming the screw portion on the inner side of the end portion and deeper than the concave portion;
An end quenching step of performing induction quenching on the open end of the end; and
Tooth part quenching step of induction hardening to the tooth part;
A first temperature tempering step of performing induction tempering at a first temperature on the end portion;
A shaft quenching step of induction hardening the shaft,
A method of manufacturing a hollow rack bar, comprising: a second temperature tempering step of performing induction tempering on the end portion, the tooth portion, and the shaft portion by a second temperature lower than the first temperature. ピニオンギアに噛み合わされる歯部が形成された中空状の軸部と、
この軸部と同じ材料で形成され、前記軸部の少なくとも一方の端の内周面に設けられ、ボールジョイントとの接続に供されるネジ部が形成された端部とを備え、
前記軸部の硬度は、前記端部の硬度より高く形成されていることを特徴とする中空ラックバー。 A shaft portion empty shape in which teeth are formed to be engaged with the pinion gear,
The shaft portion is formed of the same material, provided on the inner peripheral surface of at least one end of the shaft portion, and provided with an end portion on which a screw portion used for connection with the ball joint is formed,
The hollow rack bar is characterized in that a hardness of the shaft portion is higher than a hardness of the end portion.
JP2007085678A 2007-03-20 2007-03-28 Hollow rack bar manufacturing method and hollow rack bar Active JP5138259B2 (en)

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JP2007085678A JP5138259B2 (en) 2007-03-28 2007-03-28 Hollow rack bar manufacturing method and hollow rack bar
EP08005032A EP1972395B1 (en) 2007-03-20 2008-03-18 Apparatus and method for reducing a hollow rack end diameter and hollow rack thus obtained
DE602008000555T DE602008000555D1 (en) 2007-03-20 2008-03-18 Device and method for reducing the diameter of the end portion of a hollow rack and thus produced hollow rack
AT08005032T ATE455610T1 (en) 2007-03-20 2008-03-18 DEVICE AND METHOD FOR REDUCING THE DIAMETER OF THE END AREA OF A HOLLOW RACK AND HOLLOW RACK PRODUCED THEREFORE
US12/051,996 US8104369B2 (en) 2007-03-20 2008-03-20 Hollow rack, hollow rack end diameter reducing method, hollow rack end diameter reducing apparatus, and hollow rack manufacturing method
CN200810085186XA CN101269394B (en) 2007-03-20 2008-03-20 Hollow rack and manufacturing method, hollow rack end diameter reducing method and apparatus
CN201110080424.XA CN102225508B (en) 2007-03-20 2008-03-20 Hollow rack and manufacturing method thereof
US13/347,482 US8595936B2 (en) 2007-03-20 2012-01-10 Hollow rack end diameter reducing method
US13/347,486 US8499660B2 (en) 2007-03-20 2012-01-10 Hollow rack and hollow rack manufacturing method

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