JP2983246B2 - Manufacturing method of magnetostrictive torque sensor shaft - Google Patents
Manufacturing method of magnetostrictive torque sensor shaftInfo
- Publication number
- JP2983246B2 JP2983246B2 JP2104338A JP10433890A JP2983246B2 JP 2983246 B2 JP2983246 B2 JP 2983246B2 JP 2104338 A JP2104338 A JP 2104338A JP 10433890 A JP10433890 A JP 10433890A JP 2983246 B2 JP2983246 B2 JP 2983246B2
- Authority
- JP
- Japan
- Prior art keywords
- shaft
- carburizing
- torque sensor
- manufacturing
- magnetostrictive torque
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Description
【発明の詳細な説明】 産業上の利用分野 本発明は磁歪式トルクセンサ軸の製造方法に関する。Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetostrictive torque sensor shaft.
従来の技術 磁気異方性部を有するトルク伝達軸を利用した磁歪式
トルクセンサが、従来から知られている。このような磁
歪式トルクセンサでは、トルク伝達軸にトルクが加わる
と、そのトルクに応じて磁気異方性部の透磁率が変化す
るため、検出コイルを用いてこの透磁率の変化を検出す
ることで、加えられたトルクの大きさを求めることが可
能である。2. Description of the Related Art A magnetostrictive torque sensor using a torque transmission shaft having a magnetically anisotropic portion has been conventionally known. In such a magnetostrictive torque sensor, when a torque is applied to the torque transmission shaft, the magnetic permeability of the magnetic anisotropic portion changes according to the torque. Therefore, it is necessary to detect the change in the magnetic permeability using a detection coil. Thus, the magnitude of the applied torque can be obtained.
発明が解決しようとする課題 しかし、従来のトルクセンサでは、軸引張り強度が60
〜100kgf/mm2程度の軸（JISのSCM材、SNCM材など）を使
用しているため、軸剪断応力約20kgf/mm2程度以上のト
ルクが印加されると、磁束の通過する軸材最外表面層
（スキンデプス）の結晶の中で最も強度的に弱い結晶か
ら塑性変形を受け、またはミクロ的クラツクが発生する
という問題点があつた。そして、このような事態が生じ
ると、軸最外表面層の残留応力が再分布してセンサ出力
の零点が変化したり、ヒステリシスの増大やセンサ感度
の低下が生じたりするなど、センサにとつて望ましくな
い悪影響がもたらされるという問題点があつた。Problems to be Solved by the Invention However, in the conventional torque sensor, the axial tensile strength is 60%.
~100kgf / mm 2 about the axis (JIS SCM material, such as SNCM material) due to the use of, the axial shear stress of about 20 kgf / mm 2 of about or more torque is applied, the shaft member passing through the magnetic flux top Among the crystals of the outer surface layer (skin depth), there is a problem in that the crystal is weakest in strength and undergoes plastic deformation or micro cracks occur. When such a situation occurs, the residual stress of the outermost surface layer of the shaft is redistributed, the zero point of the sensor output changes, the hysteresis increases, and the sensor sensitivity decreases. There is a problem that undesirable adverse effects are caused.
このような問題点に対し、従来たとえば特願昭68−81
993号においては、軸に浸炭処理を行つて表面硬度を上
げることにより最外表面層の強度を上げ、結果としてセ
ンサのダイナミツクレンジの向上を図つている。しかし
これだけでは、ヒステリシス特性が改善されない場合が
あるほか、ダイナミツクレンジの改善も十分でないとい
う問題点があつた。To solve such problems, for example, Japanese Patent Application No. 68-81
In No. 993, the strength of the outermost surface layer is increased by carburizing the shaft to increase the surface hardness, and as a result, the dynamic range of the sensor is improved. However, there is a problem that the hysteresis characteristic is not improved by this alone, and that the dynamic range is not sufficiently improved.
そこで本発明はこのような問題点を解決し、ヒステリ
シス特性およびダイナミツクレンジをともに改善するこ
とのできるトルクセンサ軸の製造方法を提供することを
目的とする。Accordingly, an object of the present invention is to provide a method for manufacturing a torque sensor shaft capable of solving such problems and improving both the hysteresis characteristics and the dynamic range.
課題を解決するための手段 上記目的を達成するため本発明は、軸体の表面に磁気
異方性部を形成した後に、この軸体に浸炭処理を施し、
その後、拡散制御処理をともなった熱処理により、軸体
の最外表面層の浸炭濃度を低下させ、さらにその後、こ
の軸体の表面にシヨツトピーニングを施すものである。Means for Solving the Problems In order to achieve the above object, the present invention is to form a magnetically anisotropic portion on the surface of the shaft, and then carburize the shaft,
Thereafter, the carburizing concentration of the outermost surface layer of the shaft is reduced by a heat treatment with a diffusion control process, and thereafter, the surface of the shaft is subjected to shot peening.
浸炭処理は真空浸炭処理などの無酸化浸炭処理である
ようにすることができる。The carburizing treatment may be a non-oxidizing carburizing treatment such as a vacuum carburizing treatment.
作用 このようにすれば、浸炭処理により軸体の最外表面層
直下の部分が強化され、かつその後の拡散制御処理をと
もなった熱処理により、軸体の最外表面層の浸炭濃度を
低下させて、この領域の硬度を低下させることで、さら
にその後に続いて行われるシヨツトピーニング処理の効
果が高められる。そして、このシヨツトピーニング処理
により、最外表面層のヒステリシス特性が改善されると
同時に、最外表面層の強度が向上される。このため、過
負荷に対して強く、かつヒステリシスの少ないトルクセ
ンサが得られる。Action In this way, the portion immediately below the outermost surface layer of the shaft is strengthened by the carburizing treatment, and the carburizing concentration of the outermost surface layer of the shaft is reduced by the heat treatment with the subsequent diffusion control treatment. By reducing the hardness in this region, the effect of the subsequent shot peening process is further enhanced. By this shot peening, the hysteresis characteristics of the outermost surface layer are improved, and at the same time, the strength of the outermost surface layer is improved. Therefore, a torque sensor that is strong against overload and has little hysteresis can be obtained.
実施例 第１図および第２図は、本発明の方法によつて製造さ
れる磁歪式トルクセンサ軸の要部を示す。このようなト
ルクセンサ軸を製造する際には、まず軸体の表面に、磁
気異方性部としてのナーリング部１を、転造などの機械
加工によつて形成する。次にこの軸体の表面に浸炭処理
を施し、軸体の表面から2mm程度の深さまで炭素量が多
くなる領域を形成して、その部分の強度の向上を図る。Embodiment FIGS. 1 and 2 show a main part of a magnetostrictive torque sensor shaft manufactured by the method of the present invention. When manufacturing such a torque sensor shaft, first, a knurling portion 1 as a magnetic anisotropic portion is formed on the surface of the shaft body by machining such as rolling. Next, the surface of the shaft body is subjected to carburizing treatment to form a region where the amount of carbon is increased up to a depth of about 2 mm from the surface of the shaft body, thereby improving the strength of that portion.
その後、軸体の最外表面層すなわちスキンデプス領域
の浸炭濃度を薄くする処理を施す。これは、たとえば浸
炭後に拡散制御処理を行うことで実施できる。このよう
にすると、第１図に示すように、軸体のスキンデプス領
域に低炭素濃度浸炭層２が形成され、また、これに続い
て高炭素濃度浸炭層３が形成される。なお、軸体の中心
コア部分は母材層４で、浸炭処理による硬度すなわち強
度の向上は図られないが、トルク伝達軸として必要な靱
性を保有する。Thereafter, a treatment for reducing the carburizing concentration of the outermost surface layer of the shaft, that is, the skin depth region is performed. This can be performed, for example, by performing diffusion control processing after carburization. In this manner, as shown in FIG. 1, a low carbon concentration carburized layer 2 is formed in the skin depth region of the shaft body, and subsequently, a high carbon concentration carburized layer 3 is formed. The central core portion of the shaft body is the base material layer 4, which does not improve the hardness, that is, the strength, by carburizing, but retains the required toughness as a torque transmission shaft.
なお、浸炭処理の際に真空浸炭処理などの無酸化浸炭
処理を行うことで、軸体の最外表面層での粒界酸化など
の異常層の発生が抑えられ、センサ特性の経年変化の少
ないトルクセンサが得られる。By performing non-oxidizing carburizing such as vacuum carburizing during carburizing, the occurrence of an abnormal layer such as grain boundary oxidation in the outermost surface layer of the shaft is suppressed, and the sensor characteristics are less likely to change over time. A torque sensor is obtained.
第１図の構成のトルク伝達軸の強度分布を、第３図に
示す。このようにスキンデプス領域の浸炭濃度を薄くし
てこの領域の硬度を低下させるのは、次に述べるシヨツ
トピーニング処理の効果を高めるためである。FIG. 3 shows the strength distribution of the torque transmission shaft having the configuration shown in FIG. The reason why the carburizing concentration in the skin depth region is reduced to lower the hardness in this region is to enhance the effect of the shot peening process described below.
すなわち、第１図に示すように低炭素濃度浸炭層２と
高炭素濃度浸炭層３とが形成されたなら、次に、軸体の
表面にはシヨツトピーニングを施して微小圧孔をほぼ均
一に分散形成する。第２図は、このような微小圧孔５が
形成された状態を示す。こうすることで、特許出願特願
平１−42544号に記載された理由により、即ち軸体の表
層、特にスキンデプス領域が圧縮緻密化されるとともに
加工硬化により硬質化され、その疲労強度や結晶粒界の
すべり抵抗が高められること及びシヨツト圧孔周りの円
形安定残留応力の分布により磁化過程が主として磁化回
転となることからトルク検出特性のヒステリシスが低減
される。That is, as shown in FIG. 1, if the low carbon concentration carburized layer 2 and the high carbon concentration carburized layer 3 are formed, then the surface of the shaft is subjected to shot peening to make the minute pressure holes substantially uniform. To form a dispersion. FIG. 2 shows a state in which such minute pressure holes 5 are formed. In this way, for the reason described in Japanese Patent Application No. 1-442544, that is, the surface layer of the shaft, particularly the skin depth region is compressed and densified and hardened by work hardening, and its fatigue strength and crystallinity are increased. The hysteresis of the torque detection characteristic is reduced because the magnetization process mainly becomes the magnetization rotation due to the increase in the slip resistance of the grain boundary and the distribution of the circular stable residual stress around the shot pressure hole.
第４図は、シヨツトピーニングを施した後のトルク伝
達軸の強度分布を示す。図中、破線は第３図の特性を示
すが、これに比べて軸体の表層部、特にスキンデプス領
域での強度が大幅に向上している。FIG. 4 shows the strength distribution of the torque transmission shaft after shot peening. In the figure, the broken line shows the characteristic shown in FIG. 3, but the strength in the surface layer portion of the shaft body, particularly in the skin depth region is greatly improved.
また、このようにすると、軸体の最外表面層の炭素濃
度が低く抑えられるため、浸炭処理後の残留オーステナ
イトに帰因する異常層の発生が抑えられ、このため安定
性に優れた磁歪式トルクセンサが得られる。In addition, since the carbon concentration in the outermost surface layer of the shaft body is suppressed to be low, the occurrence of an abnormal layer due to residual austenite after carburizing is suppressed, and thus the magnetostrictive type having excellent stability. A torque sensor is obtained.
シヨツトピーニング処理が完了したなら、その後、残
留応力安定化熱処理を施す。After the shot peening process is completed, a residual stress stabilizing heat treatment is performed thereafter.
発明の効果 以上述べたように本発明によると、軸体の表面に浸炭
処理を施すことでその強度を向上させることができる。
またその後の拡散制御処理をともなった熱処理により、
軸体のスキンデプス領域の浸炭濃度を低下させて、この
領域の硬度を低下させることで、さらにその後に続いて
行われるシヨツトピーニング処理の効果を高めることが
できる。そしてスキンデプス領域では、シヨツトピーニ
ング処理が施されることで、ヒステリシス特性を優れか
つ強度を向上することができるため、過負荷に対して強
いトルクセンサ軸を得ることができる。またシヨツトピ
ーニング処理を施すことで、ヒステリシスの少ないトル
クセンサを得ることができる。Effects of the Invention As described above, according to the present invention, the strength of a shaft body can be improved by carburizing the surface of the shaft body.
In addition, by the subsequent heat treatment with diffusion control processing,
By lowering the carburizing concentration in the skin depth region of the shaft to reduce the hardness in this region, it is possible to further enhance the effect of the subsequent shot peening treatment. In the skin depth region, since the shot peening process is performed, the hysteresis characteristics can be excellent and the strength can be improved, so that a torque sensor shaft that is strong against overload can be obtained. Further, by performing the shot peening process, a torque sensor with less hysteresis can be obtained.
第１図および第２図は本発明の一実施例の方法を説明す
るための磁歪式トルクセンサ軸の一部切欠斜視図、第３
図および第４図は強度分布の例を示す図である。 １……ナーリング部、２……低炭素濃度浸炭層、３……
高炭素濃度浸炭層、５……微小圧孔。FIGS. 1 and 2 are partially cutaway perspective views of a magnetostrictive torque sensor shaft for explaining a method according to an embodiment of the present invention.
FIG. 4 and FIG. 4 are diagrams showing examples of the intensity distribution. 1 ... knurling part 2 ... low carbon concentration carburized layer 3 ...
High carbon concentration carburized layer, 5 ... minute pores.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉村 茂夫 大阪府枚方市中宮大池１丁目１番１号 株式会社クボタ枚方製造所内 (72)発明者 砂畠 睦巳 大阪府枚方市中宮大池１丁目１番１号 株式会社クボタ枚方製造所内 (56)参考文献 特開 平２−98639（ＪＰ，Ａ) 特開 平２−90030（ＪＰ，Ａ) 特開 平１−169983（ＪＰ，Ａ) 特開 昭63−81993（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) G01L 3/10 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeo Yoshimura 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Plant Co., Ltd. (72) Inventor Mutsumi Sunahata 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture No. 1 Inside Kubota Hirakata Factory (56) References JP-A-2-98639 (JP, A) JP-A-2-90030 (JP, A) JP-A-1-169983 (JP, A) JP-A-63 -81993 (JP, A) (58) Field surveyed (Int. Cl. 6 , DB name) G01L 3/10
Claims (2)
に、この軸体に浸炭処理を施し、その後、拡散制御処理
をともなった熱処理により、軸体の最外表面層の浸炭濃
度を低下させ、さらにその後、軸体の表面にシヨツトピ
ーニングを施すことを特徴とする磁歪式トルクセンサ軸
の製造方法。After forming a magnetically anisotropic portion on the surface of a shaft, the shaft is subjected to a carburizing treatment, and thereafter, a carburizing concentration of an outermost surface layer of the shaft is subjected to a heat treatment with a diffusion control treatment. And then subjecting the surface of the shaft body to shot peening.
処理であることを特徴とする請求項１記載の磁歪式トル
クセンサ軸の製造方法。2. The method for manufacturing a magnetostrictive torque sensor shaft according to claim 1, wherein the carburizing process is a non-oxidizing carburizing process such as a vacuum carburizing process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2104338A JP2983246B2 (en) | 1990-04-18 | 1990-04-18 | Manufacturing method of magnetostrictive torque sensor shaft |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2104338A JP2983246B2 (en) | 1990-04-18 | 1990-04-18 | Manufacturing method of magnetostrictive torque sensor shaft |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH041542A JPH041542A (en) | 1992-01-07 |
| JP2983246B2 true JP2983246B2 (en) | 1999-11-29 |
Family
ID=14378142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2104338A Expired - Lifetime JP2983246B2 (en) | 1990-04-18 | 1990-04-18 | Manufacturing method of magnetostrictive torque sensor shaft |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2983246B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5491369A (en) * | 1992-08-24 | 1996-02-13 | Kubota Corporation | Magnetostrictive torque sensor shaft |
| JP5306795B2 (en) * | 2008-12-24 | 2013-10-02 | ヤマハ発動機株式会社 | Connecting rod, internal combustion engine, transportation device, and manufacturing method of connecting rod |
| US20190178683A1 (en) | 2016-05-17 | 2019-06-13 | Kongsberg Inc. | System, Method And Object For High Accuracy Magnetic Position Sensing |
| CN110088583B (en) | 2016-12-12 | 2021-07-30 | 康斯博格股份有限公司 | Dual-band magnetoelastic torque sensor |
| US10983019B2 (en) | 2019-01-10 | 2021-04-20 | Ka Group Ag | Magnetoelastic type torque sensor with temperature dependent error compensation |
-
1990
- 1990-04-18 JP JP2104338A patent/JP2983246B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH041542A (en) | 1992-01-07 |
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