JP4098117B2

JP4098117B2 - Axle case

Info

Publication number: JP4098117B2
Application number: JP2003053579A
Authority: JP
Inventors: 陸夫大崎; 久直丸山
Original assignee: Press Kogyo Co Ltd
Current assignee: Press Kogyo Co Ltd
Priority date: 2003-02-28
Filing date: 2003-02-28
Publication date: 2008-06-11
Anticipated expiration: 2023-02-28
Also published as: JP2004262302A

Description

【０００１】
【発明の属する技術分野】
本発明は、車軸ケースに係り、特に、本体とスピンドルとの接合部の強度向上を図った車軸ケースに関するものである。
【０００２】
【従来の技術】
車軸ケースとは、トラック等、車両の駆動車軸及びディファレンシャルギヤ等を収容するためのものであり、図７に示すように、車両の車幅方向に延出し、上下に重ね合わせて接合された上部材３０と下部材３１とで構成され、長手方向両端部がほぼ円筒形状に形成された本体３８と、その本体３８の長手方向両端部に接合されるほぼ円筒形状のスピンドル３３とを備える。上下部材３０，３１は、その長手方向中央部が上方又は下方に湾曲しており、本体３８の長手方向中央部には略円形の穴（図示せず）が形成される。本体３８には、その穴を覆うように半球形状のカバー部材３２が取り付けられる。このような車軸ケース３４は、例えば特許文献１等にも記載されている。
【０００３】
このような車軸ケース３４において、本体３８の長手方向両端部とスピンドル３３とは溶接接合される。つまり、図８に示すように、本体３８の端部とスピンドル３３の端部とを互いに突き合わせて隅肉溶接して接合する。なお、図８は本体３８とスピンドル３３との上部接合部の断面を示している。
【０００４】
ところで、車軸ケース３４には車両の加減速や方向転換、及び走行路面の凹凸等によって様々な負荷やモーメントが作用する。特に、車軸ケース３４を上又は下方向へと曲げるようなモーメントが作用することが多い。例えば、スピンドル３３の外周部には車輪が設けられるため、路面から上方向への反力をうけた場合、車軸ケース３４の長手方向ほぼ中央部を支点として、長手方向両端部を上方へと持ち上げるようなモーメントＭ１（図７参照）が作用する。その結果、本体３８とスピンドル３３との接合部に応力が発生する。
【０００５】
このため、本体３８とスピンドル３３との接合部には比較的高い強度が要求される。そこで従来から、本体３８とスピンドル３３との接合部の溶接溶け込み率が、本体３８及びスピンドル３３の板厚に対して１００％となるようにしている。
【０００６】
板材の突き合わせ溶接において、溶接溶け込み率を１００％とする場合、板材の表裏両側から溶接するのが一般的であるが、スピンドル３３はその外側端部が縮径された形状であるため、溶接ロッド等を内部に挿入しずらく、裏から溶接することが困難である。そこで、表側からの溶接だけで１００％の溶け込み率を確保すべく大きな入熱を与えると、接合部の裏側に溶融金属が滴れ落ち、車軸ケース３４内に組み込まれる駆動車軸等と干渉してしまう虞がある。また、極端な場合では、接合部に穴が開いてしまい油漏れや接合部の強度低下に繋がる。
【０００７】
そこで、図８に示すように、本体３８とスピンドル３３との接合部の内側に円筒形状の当金３９を挿入するようにしている。こうすれば、溶接の溶け込み率を１００％としても、溶融金属が車軸ケース３４内部に滴り落ちることを防止できる。なお、当金３９は、本体３８又はスピンドル３３の内側に一体に成形されることもある。
【０００８】
【特許文献１】
特開平０８−０６７１０８号公報
【０００９】
【発明が解決しようとする課題】
しかしながら、このような従来の車軸ケースでは、溶接溶け込み率を１００％としても、本体３８とスピンドル３３との接合部に亀裂等が発生することがあり、更なる強度向上が望まれていた。
【００１０】
例えば、本体３８と当金３９、及びスピンドル３３と当金３９との接触面における未溶着部分４０が、予め形成された亀裂として作用してしまい、接合部の内面側の溶接ルート部４１に応力が集中し、そこから亀裂が発生してしまう場合がある。
【００１１】
また、本体３８とスピンドル３３との接合部には、溶接後の溶着金属の収縮により残留応力が発生するが、このとき、接合部の外面側には強度上有利となる長手方向（図中左右方向）の圧縮応力が残留するが、接合部の内面側には強度上不利となる長手方向の引張応力が残留してしまう。
【００１２】
つまり、本体３８とスピンドル３３との接合部の内面側は、もともと引張応力が残留しているうえに、車軸ケース３４に外力が加わったときに応力が集中するため、亀裂等が発生する可能性が高いのである。
【００１３】
そこで、本発明の目的は、上記課題を解決し、本体とスピンドルとの接合部の強度向上を図った車軸ケースを提供することにある。
【００１４】
【課題を解決するための手段】
上記目的を達成するために本発明は、上下に重ね合わせて接合された上部材と下部材とで構成され、長手方向両端部が略円筒状に形成された本体と、その本体の長手方向両端部に夫々突き合わせて外周側から溶接された略円筒状のスピンドルとを備えた車軸ケースであって、上記スピンドルは、上記本体が突き合わせて溶接される略円筒状の接合端部と、該接合端部に繋げて形成され車幅方向外側に向けて徐々に拡径された傾斜部と、該傾斜部に繋げて形成され上記接合端部よりも大径の略円筒状の隣接部とを有し、該隣接部の上下方向寸法と上記接合端部の上下方向寸法との差が、上記接合端部の板厚の２０〜５０％の範囲内であり、上記傾斜部と上記接合端部との境目から上記接合端部の端面までの長さが、上記接合端部の板厚の１〜２倍の範囲内であるものである。
【００１５】
この構成によれば、本体とスピンドルとの板厚中心を通る線が屈曲して形成されるため、本体とスピンドルとの接合部に引張応力が発生したときに、その作用点が接合部の板厚中心から径方向外方にずれる。その結果、接合部の内面側に圧縮応力が発生するようなモーメントが作用する。従って、接合部の内面側には引張応力と圧縮応力との、相反する二つの応力が発生する。この相反する応力が互いに打ち消し合うため、接合部の内面側に発生する応力は小さくなり、接合部の強度及び寿命向上につながる。
【００１６】
また、上下に重ね合わせて接合された上部材と下部材とで構成され、長手方向両端部が略円筒状に形成された本体と、その本体の長手方向両端部に夫々突き合わせて外周側から溶接された略円筒状のスピンドルとを備えた車軸ケースであって、上記本体は、上記スピンドルが突き合わせて溶接される略円筒状の接合端部と、該接合端部に繋げて形成され車幅方向中央側に向けて徐々に拡径された傾斜部と、該傾斜部に繋げて形成され上記接合端部よりも大径の略円筒状の隣接部とを有し、上記スピンドルは、上記本体が突き合わせて溶接される略円筒状の接合端部と、該接合端部に繋げて形成され車幅方向外側に向けて徐々に拡径された傾斜部と、該傾斜部に繋げて形成され上記接合端部よりも大径の略円筒状の隣接部とを有し、上記本体の隣接部の上下方向寸法と上記本体の接合端部の上下方向寸法との差が、上記本体の接合端部の板厚の２０〜５０％の範囲内であり、上記スピンドルの隣接部の上下方向寸法と上記スピンドルの接合端部の上下方向寸法との差が、上記スピンドルの接合端部の板厚の２０〜５０％の範囲内であり、上記本体の傾斜部と上記本体の接合端部との境目から上記本体の接合端部の端面までの長さが、上記本体の接合端部の板厚の１〜２倍の範囲内であり、上記スピンドルの傾斜部と上記スピンドルの接合端部との境目から上記スピンドルの接合端部の端面までの長さが、上記スピンドルの接合端部の板厚の１〜２倍の範囲内であってもよい。
【００１８】
【発明の実施の形態】
以下、本発明の好適な一実施形態を添付図面に基づいて詳述する。
【００１９】
図１は本発明の実施形態ではない参考形態に係る車軸ケースの本体とスピンドルとの上部接合部の拡大断面図である。本参考形態の車軸ケースの概略構成は図７に示したものと同様である。
【００２０】
即ち、本参考形態の車軸ケースは、上下に重ね合わせて接合された上部材３０と下部材３１とで構成され、長手方向両端部がほぼ円筒形状に形成された本体３８と、その本体３８の長手方向両端部に接合されるほぼ円筒形状のスピンドル３３とを備える。上下部材３０，３１は、その長手方向中央部が上方又は下方に湾曲しており、本体３８の長手方向中央部には略円形の穴（図示せず）が形成される。本体３８には、その穴を覆うように半球形状のカバー部材３２が取り付けられる。
【００２１】
図１に示すように、本体３８及びスピンドル３３の端部は互いに突き合わされ、その突き合わせ部の内側に円筒形状の当金３９が挿入・配置される。そして、本体３８及びスピンドル３３の外面側（図中上側）から隅肉溶接を行って互いに接合する。この際、溶接の溶け込み率は、本体３８及びスピンドル３３の接合端部１，２の板厚Ｔに対して１００％とされる。なお、本体３８の接合端部１の板厚と、スピンドル３３の接合端部２の板厚とはほぼ等しい。
【００２２】
本参考形態の車軸ケースの特徴は、本体３８におけるスピンドル３３との接合端部１が、その接合端部１に連続する隣接部４と比べて縮径されている点にある。具体的には、本体３８は、スピンドル３３の接合端部２と同じ径に形成された接合端部（縮径部）１と、その接合端部１に傾斜部３を介して連続し、接合端部１よりも大きな径を有する隣接部４とを備える。つまり、図２にも示すように、本体３８は、その端部が段差状に形成される。このような段差状の本体３８は、上部材３０及び下部材３１をプレス成形する際に、各々の端部を段差状に成形することで比較的容易に製造できる。
【００２３】
このように、本体３８の接合端部１を、それに連続する隣接部４よりも縮径することによって、車軸ケースに負荷やモーメントが作用したときに、本体３８とスピンドル３３との接合部５、特に接合部５の内面側に発生する応力を低減でき、接合部５の強度及び寿命を向上させることができる。その理由について、以下説明する。
【００２４】
まず、図２に示すように、本体３８とスピンドル３３との上部接合部において、接合部５から長手方向両側に延出し、かつ一定の幅Ｗを有する領域を微少要素Ｃとして取り出す。微少要素Ｃの側面図を図３に示す。なお、図３では便宜上、溶着金属及び当金３９は省略している。
【００２５】
いま、車軸ケースに対して、本体３８とスピンドル３３との上部接合部５に引張応力が発生するようなモーメントＭ２が作用したとする（図２参照）。つまり、車軸ケースに対して、長手方向のほぼ中央部を支点として両端部を下方に押すようなモーメントが作用した場合である。このとき、図３に示すように、微少要素Ｃには本体３８とスピンドル３３とを引き離す方向の引張応力ＴＳが発生する。
【００２６】
ここで、本体３８の接合端部１が、隣接部４に対して縮径されているため、本体３８及びスピンドル３３の板厚中心を通る線ＣＬは屈曲する。一方、引張応力ＴＳによって接合部５に作用する負荷は微少要素Ｃの長手方向両端部の板厚中心間を結ぶ作用線ＡＬに沿って作用する。従って、接合部５における引張応力ＴＳの作用点ＡＰは、接合部５の板厚中心ＳＣから径方向外側（上側）に距離Ｈだけずれる。その結果、接合部５には、図に示すように、接合部５の板厚中心ＳＣを中心としてその両側を径方向内側（下側）に押すような局部モーメントＭ３が作用する。これにより、接合部５の外面側には引張応力が発生し、内面側には圧縮応力ＣＳが発生する。
【００２７】
結果として、接合部５の内面側には、車軸ケースに作用するモーメントＭ２により発生する引張応力ＴＳと、その引張応力ＴＳが接合部５の板厚中心ＳＣからずれた位置に作用することにより発生する圧縮応力ＣＳとの、相反する二つの応力が発生する。この相反する応力が互いに打ち消し合うため、接合部５の内面側に発生する応力は小さくなり、接合部５の強度及び寿命向上につながる。
【００２８】
つまり、接合部５には、図４（ａ）に示すような、径方向全ての位置でほぼ均一な引張応力（＋）と、図４（ｂ）に示すような、板厚中心ＳＣよりも径方向外側では引張応力（＋）となり、板厚中心ＳＣよりも径方向内側では圧縮応力（−）となるような二つの応力が発生する。結果として、接合部５に発生する応力は、図４（ｃ）に示すようになり、接合部５の内面側に発生する応力は小さくなる。
【００２９】
例えば、図８に示したような従来の接合部構造では、本体３８及びスピンドル３３の板厚中心を通る線が直線状であるため、図３に示すような局部モーメントＭ３は発生せず、接合部の内面側には引張応力のみが発生する。従って、本実施形態と比較して、接合部の内面側には大きな引張応力が発生する。
【００３０】
このように、本参考形態の車軸ケースは、本体３８の接合端部１を、それに連続する隣接部４よりも縮径し、接合部５に発生する引張応力ＴＳの作用点ＡＰを接合部５の板厚中心ＳＣからずらすことで、接合部５の内面側に、引張応力ＴＳをうち消す圧縮応力ＣＳを発生させるようにしたものである。これによって、接合部５の強度が向上し、亀裂の発生寿命や疲労破壊寿命が延びる。従って、本実施形態の車軸ケースによれば、非常にシンプルな構造で、かつ低コストで接合部５の強度及び寿命の向上を図ることができる。
【００３１】
なお、本参考形態の車軸ケースでは、接合部５の外面側に発生する引張応力は大きくなるが、このことはあまり大きな問題とはならない。その理由を説明すると、接合部５の外面側には応力が極度に集中するポイントが無いからである。しいて挙げれば、溶着金属の長手方向両端部の止端部７（図１参照）に応力が集中するが、接合部５の外面側には応力緩和対策を容易に行うことができる。例えば、接合部５の外面側をグラインダで削ったり、ショットブラストを施すことなどにより、止端部７への応力集中を回避できる。また、接合部５の外面側には溶接後の溶着金属の収縮による圧縮残留応力が存在するため、ある程度の引張応力は吸収される。これも、接合部５の外面側が強度的に有利な理由である。従って、接合部５の外面側に発生する応力がある程度大きくなっても、内面側に発生する応力を低減すれば、接合部５全体としての強度を向上させることができる。
【００３２】
本発明者らは、本参考形態の効果を確認すべく、端部の径を縮径させた円筒部材（パイプ）に対して、その端部を下方に押すようなモーメントを加えたときに、パイプの上部断面の外面及び内面に発生する応力の解析（シミュレーション）を行った。その結果を図５に示す。
【００３３】
図中、横軸はパイプの板厚に対するパイプ端部の縮径率であり、パイプの板厚をＴ、パイプの基本直径Ｄ１と端部（縮径部）の直径Ｄ２との差をΔＤ（＝Ｄ１−Ｄ２）とすると、ΔＤ／Ｔ×１００％で表されるものである。また、図中縦軸は、端部が縮径されていない通常のパイプに同一のモーメントを加えたときにパイプの上部断面の外面及び内面に発生する応力を１００とし、それに対して縮径パイプに発生する応力の割合を示したものである。図中、丸ポイントで示す線はパイプ上部断面の内面に発生する応力を示しており、三角ポイントで示す線は外面に発生する応力を示している。
【００３４】
図から分かるように、縮径率が０から大きくなる、つまり、パイプ端部の径が小さくなるほど、内面に発生する応力は小さくなる。しかしながら、縮径率が約８０％を越えたあたりから内面に発生する応力は逆に大きくなる。つまり、端部の径をあまり小さくしすぎると応力低減効果が小さくなってしまうことが分かる。従って、内面側だけを考慮するのであれば、端部の縮径率は８０％程度にするのが好ましい。しかしながら、図からも分かるように、端部の縮径率が大きくなるほど、外面に発生する応力が比例的に上昇する。本発明者らは、内面及び外面に発生する応力のバランスをとって、接合部５の全体強度を最適に向上させるには、縮径率を２０〜５０％の範囲内にすれば良いことを確認した。つまり、縮径率がこの範囲内であれば、内面に発生する応力を充分に低減でき、かつ、外面に発生する応力が過度に大きくならず、最適なバランスとなる。従って、図１に示したような本実施形態の車軸ケースにおいて、本体３８の接合端部１の径と、隣接部４の径との差を、接合端部１の板厚Ｔに対して２０〜５０％の範囲内とすることが好ましい。
【００３５】
更に本発明者らは、図１に示す接合端部１の長さＬを、接合端部１の板厚Ｔの１〜２倍の範囲内にすることが好ましいことを確認した。つまり、接合端部１の長さＬが短すぎると、本体３８（上下部材３０，３１）の成形が困難になり、逆に長すぎると、接合部５に作用する局部モーメントＭ３（図３参照）が小さくなるため、応力低減効果は小さくなってしまう。
【００３６】
上述の参考形態では本体３８の接合端部１を縮径した例を説明したが、本発明の実施形態は、同様の考え方に基づき、図６（ａ）に示すように、スピンドル３３の接合端部２を、それに連続する隣接部１０に対して縮径したもの、又は、図６（ｂ）に示すように、本体３８及びスピンドル３３の両方の接合端部１，２を縮径したものである。これらの形態でも、図１に示した形態と同様の効果を得ることができる。
【００３７】
また、本発明は、本体３８及び／又はスピンドル３３の接合端部１，２を、必ずしも全周に渡って縮径する必要はない。つまり、「従来の技術」の欄で説明したように、車軸ケースに作用するモーメントは上下方向に作用することが多いので、本体３８及び／又はスピンドル３３の接合端部１，２の少なくとも上下方向の寸法長さを、接合端部１，２に連続する隣接部４，１０の上下方向寸法と比べて小さくなるようにすれば良い。その場合、本体３８及び／又はスピンドル３３を金型に嵌めて上下方向に圧縮（プレス）して、左右方向寸法は変えずに上下方向寸法のみを短くしても良い。あるいは、本体３８及び／又はスピンドル３３を単に上下方向から押しつぶしてほぼ楕円形状に成形しても良い。本体３８及び／又はスピンドル３３を単に押しつぶして成形する場合、金型等が必要とならないため、より低コストでの提供が可能となる。これらの加工は、本体３８とスピンドル３３とを接合する前に行っても、接合後に行っても良い。
【００３８】
これまで、本体３８及び／又はスピンドル３３の接合端部１，２を隣接部４，１０に対して縮径するとして説明したが、これとは逆に、本体３８及び／又はスピンドル３３の隣接部４，１０を拡径しても良いことは勿論である。
【００３９】
【発明の効果】
以上要するに本発明によれば、シンプルかつ低コストで本体とスピンドルとの接合部の強度向上を図ることができるという優れた効果を発揮するものである。
【図面の簡単な説明】
【図１】本発明の実施形態ではない参考形態に係る車軸ケースにおける本体とスピンドルとの上部接合部の拡大断面図である。
【図２】図１の車軸ケースにおける本体とスピンドルとの接合部を示す斜視図である。
【図３】本体とスピンドルとの接合部に発生する応力を説明するための説明図である。
【図４】（ａ）は、本体とスピンドルとの接合部に発生する引張応力を示している。
（ｂ）は、本体とスピンドルとの接合部に作用する局部モーメントによって接合部に発生する応力を示している。
（ｃ）は、本体とスピンドルとの接合部に発生する応力を示している。
【図５】パイプ端部の縮径率と、パイプの上部断面の外面及び内面に発生する応力との関係を示すグラフである。
【図６】（ａ）は、本発明の一実施形態の車軸ケースにおける本体とスピンドルとの上部接合部の拡大断面図である。
（ｂ）は、本発明の他の実施形態の車軸ケースにおける本体とスピンドルとの上部接合部の拡大断面図である。
【図７】車軸ケースの正面図である。
【図８】従来の車軸ケースにおける本体とスピンドルとの上部接合部の拡大断面図である。
【符号の説明】
１，２接合端部
４，１０隣接部
５接合部
３０上部材
３１下部材
３３スピンドル
３８本体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an axle case, and more particularly, to an axle case that improves the strength of a joint portion between a main body and a spindle.
[0002]
[Prior art]
The axle case is for housing a drive axle of a vehicle, a differential gear, etc., such as a truck. As shown in FIG. 7, the axle case extends in the vehicle width direction of the vehicle and is overlapped and joined in the vertical direction. The main body 38 is composed of a member 30 and a lower member 31, and both end portions in the longitudinal direction are formed in a substantially cylindrical shape, and a substantially cylindrical spindle 33 joined to both end portions in the longitudinal direction of the main body 38. The upper and lower members 30, 31 have a longitudinal center portion curved upward or downward, and a substantially circular hole (not shown) is formed in the longitudinal center portion of the main body 38. A hemispherical cover member 32 is attached to the main body 38 so as to cover the hole. Such an axle case 34 is also described in, for example, Patent Document 1 and the like.
[0003]
In such an axle case 34, both longitudinal ends of the main body 38 and the spindle 33 are welded. That is, as shown in FIG. 8, the end portion of the main body 38 and the end portion of the spindle 33 are brought into contact with each other, and are joined by fillet welding. FIG. 8 shows a cross section of the upper joint between the main body 38 and the spindle 33.
[0004]
By the way, various loads and moments act on the axle case 34 due to acceleration / deceleration and direction change of the vehicle, unevenness of the traveling road surface, and the like. In particular, a moment that bends the axle case 34 upward or downward often acts. For example, since a wheel is provided on the outer peripheral portion of the spindle 33, when a reaction force is applied upward from the road surface, both longitudinal ends are lifted upward with the longitudinal center portion of the axle case 34 as a fulcrum. Such a moment M1 (see FIG. 7) acts. As a result, a stress is generated at the joint between the main body 38 and the spindle 33.
[0005]
For this reason, a relatively high strength is required for the joint between the main body 38 and the spindle 33. Therefore, conventionally, the welding penetration rate of the joint portion between the main body 38 and the spindle 33 is set to 100% with respect to the plate thickness of the main body 38 and the spindle 33.
[0006]
In butt welding of plate materials, when the welding penetration rate is 100%, it is common to weld from both the front and back sides of the plate material, but the spindle 33 has a shape whose outer end is reduced in diameter, so a welding rod Etc. are difficult to insert inside and difficult to weld from the back. Therefore, if a large heat input is applied to ensure a 100% penetration rate only by welding from the front side, the molten metal will drip on the back side of the joint, interfering with the drive axle incorporated in the axle case 34, etc. There is a risk of it. In an extreme case, a hole is formed in the joint, leading to oil leakage and a decrease in strength of the joint.
[0007]
Therefore, as shown in FIG. 8, a cylindrical abutment 39 is inserted inside the joint portion between the main body 38 and the spindle 33. By doing so, it is possible to prevent the molten metal from dripping into the axle case 34 even if the welding penetration rate is set to 100%. The gold 39 may be integrally formed inside the main body 38 or the spindle 33.
[0008]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 08-0667108
[Problems to be solved by the invention]
However, in such a conventional axle case, even if the welding penetration rate is set to 100%, a crack or the like may occur at the joint between the main body 38 and the spindle 33, and further improvement in strength has been desired.
[0010]
For example, the unwelded portion 40 in the contact surface between the main body 38 and the metal 39 and the spindle 33 and the metal 39 acts as a pre-formed crack, and stress is applied to the weld route portion 41 on the inner surface side of the joint portion. May concentrate and cracks may occur from there.
[0011]
Residual stress is generated at the joint between the main body 38 and the spindle 33 due to the shrinkage of the weld metal after welding. At this time, the longitudinal direction (left and right in the figure) is advantageous on the outer surface side of the joint. Direction), but the tensile stress in the longitudinal direction, which is disadvantageous in strength, remains on the inner surface side of the joint.
[0012]
That is, the inner surface side of the joint portion between the main body 38 and the spindle 33 originally has a residual tensile stress, and the stress is concentrated when an external force is applied to the axle case 34, so that a crack or the like may occur. Is expensive.
[0013]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an axle case that solves the above problems and improves the strength of the joint between the main body and the spindle.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises a main body formed of an upper member and a lower member that are joined one above the other in the vertical direction, both ends in the longitudinal direction formed in a substantially cylindrical shape, and both ends in the longitudinal direction of the main body. parts to a front axle case having a respective butt substantially cylindrical spindle which is welded from the outer side, the spindle has a substantially cylindrical joint end portion in which the body is welded butt, the joint end Yes an inclined portion which is gradually enlarged toward the formed vehicle width direction outer side by connecting the parts, and a substantially cylindrical abutment having a larger diameter than formed by connecting to the inclined portion the joint ends And the difference between the vertical dimension of the adjacent portion and the vertical dimension of the joint end is within a range of 20 to 50% of the plate thickness of the joint end, and the inclined portion and the joint end The length from the boundary to the end surface of the joint end is 1-2 of the plate thickness of the joint end It is intended to be within the scope of.
[0015]
According to this configuration, since the line passing through the center of the plate thickness between the main body and the spindle is formed by bending, when the tensile stress is generated at the joint portion between the main body and the spindle, the action point is the plate of the joint portion. It deviates radially outward from the thickness center. As a result, a moment that generates compressive stress acts on the inner surface side of the joint. Therefore, two opposing stresses, tensile stress and compressive stress, are generated on the inner surface side of the joint. Since these opposing stresses cancel each other, the stress generated on the inner surface side of the joint is reduced, leading to an improvement in the strength and life of the joint.
[0016]
In addition, it is composed of an upper member and a lower member that are superposed and joined together, and a main body in which both longitudinal end portions are formed in a substantially cylindrical shape, and the longitudinal end portions of the main body are respectively butted from the outer peripheral side. An axle case having a substantially cylindrical spindle, wherein the main body has a substantially cylindrical joint end to which the spindle abuts and is welded, and is connected to the joint end and is formed in the vehicle width direction. An inclined portion that is gradually enlarged in diameter toward the center side, and a substantially cylindrical adjacent portion that is connected to the inclined portion and has a larger diameter than the joining end portion. A substantially cylindrical joining end portion to be welded in contact with each other, an inclined portion formed so as to be connected to the joining end portion and gradually expanded toward the outside in the vehicle width direction, and connected to the inclined portion. and a substantially cylindrical adjacent portion of the large diameter than the end portion, of the main body The difference between the vertical dimension of the joint end portion of the vertical dimension and the body of the contact portion is a in 20% to 50% range of thickness of the joint end portion of the main body, the vertical direction of the adjacent portion of the spindle the difference between the vertical dimension of the joint end portion of the dimensions and the spindle is in the plate 20% to 50% range for the thickness of the joint end portion of the spindle, a joint end portion of the inclined portion and the main body of the body The length from the boundary of the main body to the end face of the joint end of the main body is within a range of 1 to 2 times the plate thickness of the joint end of the main body, and the inclined part of the spindle and the joint end of the spindle from boundary length to the end surface of the joint end portion of the spindle may be in a plate thickness range 1-2 times the of the joint end portion of the spindle.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is an enlarged cross-sectional view of an upper joint portion between a main body and a spindle of an axle case according to a reference embodiment which is not an embodiment of the present invention . Schematic configuration of axle case of the present reference embodiment is the same as that shown in FIG.
[0020]
That is, the axle case of the present reference embodiment is composed of an upper member 30 is joined superimposed vertically with the lower member 31, a body 38 in the longitudinal direction both end portions is formed in a substantially cylindrical shape, the body 38 And a substantially cylindrical spindle 33 joined to both ends in the longitudinal direction. The upper and lower members 30, 31 have a longitudinal center portion curved upward or downward, and a substantially circular hole (not shown) is formed in the longitudinal center portion of the main body 38. A hemispherical cover member 32 is attached to the main body 38 so as to cover the hole.
[0021]
As shown in FIG. 1, the end portions of the main body 38 and the spindle 33 are abutted with each other, and a cylindrical abutment 39 is inserted and disposed inside the abutting portion. Then, fillet welding is performed from the outer surface side (upper side in the drawing) of the main body 38 and the spindle 33 to join each other. At this time, the penetration rate of welding is set to 100% with respect to the plate thickness T of the joining end portions 1 and 2 of the main body 38 and the spindle 33. The plate thickness of the joining end 1 of the main body 38 and the plate thickness of the joining end 2 of the spindle 33 are substantially equal.
[0022]
Features of the axle case of the present reference embodiment, the joint end portion 1 of the spindle 33 in the body 38 is in that it is reduced in diameter as compared with the adjacent portion 4 continuous to the joint end portion 1. Specifically, the main body 38 is connected to a joint end (reduced diameter portion) 1 having the same diameter as the joint end 2 of the spindle 33, and the joint end 1 via the inclined portion 3. And an adjacent portion 4 having a diameter larger than that of the end portion 1. That is, as shown in FIG. 2, the end portion of the main body 38 is formed in a stepped shape. Such a step-shaped main body 38 can be relatively easily manufactured by forming each end in a step shape when the upper member 30 and the lower member 31 are press-molded.
[0023]
Thus, when the load or moment acts on the axle case by reducing the diameter of the joint end portion 1 of the main body 38 than the adjacent portion 4 continuous thereto, the joint portion 5 between the main body 38 and the spindle 33, In particular, the stress generated on the inner surface side of the joint portion 5 can be reduced, and the strength and life of the joint portion 5 can be improved. The reason will be described below.
[0024]
First, as shown in FIG. 2, in the upper joint portion between the main body 38 and the spindle 33, a region extending from the joint portion 5 on both sides in the longitudinal direction and having a certain width W is taken out as a minute element C. A side view of the minute element C is shown in FIG. In FIG. 3, for the sake of convenience, the weld metal and the gold 39 are omitted.
[0025]
Now, it is assumed that a moment M2 that generates a tensile stress is applied to the upper case 5 of the main body 38 and the spindle 33 on the axle case (see FIG. 2). In other words, this is a case where a moment is applied to the axle case that pushes both ends downward with a substantially central portion in the longitudinal direction as a fulcrum. At this time, as shown in FIG. 3, a tensile stress TS is generated in the minute element C in a direction in which the main body 38 and the spindle 33 are separated from each other.
[0026]
Here, since the joining end portion 1 of the main body 38 is reduced in diameter with respect to the adjacent portion 4, the line CL passing through the center thickness of the main body 38 and the spindle 33 is bent. On the other hand, the load acting on the joint portion 5 due to the tensile stress TS acts along the action line AL connecting the center of the plate thickness at both longitudinal ends of the minute element C. Therefore, the application point AP of the tensile stress TS at the joint 5 is shifted by the distance H from the plate thickness center SC of the joint 5 to the radially outer side (upper side). As a result, as shown in the figure, a local moment M3 is exerted on the joint portion 5 so as to push the both sides radially inward (downward) about the plate thickness center SC of the joint portion 5. As a result, tensile stress is generated on the outer surface side of the joint 5 and compressive stress CS is generated on the inner surface side.
[0027]
As a result, the inner surface side of the joint 5 is generated by the tensile stress TS generated by the moment M2 acting on the axle case and the position where the tensile stress TS deviates from the plate thickness center SC of the joint 5. Two opposing stresses occur with the compressive stress CS. Since the opposing stresses cancel each other, the stress generated on the inner surface side of the joint portion 5 is reduced, leading to an improvement in strength and life of the joint portion 5.
[0028]
That is, the joint 5 has a substantially uniform tensile stress (+) at all radial positions as shown in FIG. 4A and a thickness center SC as shown in FIG. 4B. Two stresses are generated which are tensile stress (+) on the radially outer side and compressive stress (−) on the radially inner side of the plate thickness center SC. As a result, the stress generated in the joint 5 is as shown in FIG. 4C, and the stress generated on the inner surface side of the joint 5 is reduced.
[0029]
For example, in the conventional joint structure as shown in FIG. 8, since the line passing through the center of the plate thickness of the main body 38 and the spindle 33 is linear, the local moment M3 as shown in FIG. Only the tensile stress is generated on the inner surface side of the portion. Therefore, compared with this embodiment, a large tensile stress is generated on the inner surface side of the joint.
[0030]
Thus, axle case of the present reference embodiment, the joint end portion 1 of the body 38, a reduced diameter than the adjacent portion 4 continuous to it, the joint action point AP tensile stress TS that occurs in the bonding portion 5 5 The compressive stress CS that eliminates the tensile stress TS is generated on the inner surface side of the joint 5 by shifting from the plate thickness center SC. Thereby, the strength of the joint portion 5 is improved, and the life of cracks and the life of fatigue failure are extended. Therefore, according to the axle case of the present embodiment, the strength and life of the joint 5 can be improved with a very simple structure and at low cost.
[0031]
In the axle case of this preferred embodiment, the tensile stress generated on the outer surface side of the joint portion 5 but is increased, this is not a very big problem. The reason will be explained because there is no point at which stress is extremely concentrated on the outer surface side of the joint portion 5. In other words, stress concentrates on the toe ends 7 (see FIG. 1) at both ends in the longitudinal direction of the weld metal, but stress relaxation measures can be easily taken on the outer surface side of the joint 5. For example, stress concentration on the toe portion 7 can be avoided by grinding the outer surface side of the joint portion 5 with a grinder or performing shot blasting. Further, since a compressive residual stress due to shrinkage of the weld metal after welding exists on the outer surface side of the joint portion 5, a certain amount of tensile stress is absorbed. This is also the reason why the outer surface side of the joint portion 5 is advantageous in terms of strength. Therefore, even if the stress generated on the outer surface side of the joint portion 5 increases to some extent, the strength of the joint portion 5 as a whole can be improved by reducing the stress generated on the inner surface side.
[0032]
The present inventors, in order to confirm the effect of this preferred embodiment, the cylindrical member reduced in diameter the diameter of the end portion (pipe), when added to a moment to press the end portion downwards, Analysis (simulation) of the stress generated on the outer and inner surfaces of the upper cross section of the pipe was performed. The result is shown in FIG.
[0033]
In the figure, the horizontal axis represents the diameter reduction ratio of the pipe end with respect to the pipe thickness. The pipe thickness is T, and the difference between the basic diameter D1 of the pipe and the diameter D2 of the end (reduced diameter portion) is ΔD ( = D1-D2), it is represented by ΔD / T × 100%. Also, the vertical axis in the figure represents 100 as the stress generated on the outer and inner surfaces of the upper cross section of the pipe when the same moment is applied to a normal pipe whose end is not reduced in diameter, and the reduced diameter pipe The ratio of the stress generated in is shown. In the figure, a line indicated by a round point indicates the stress generated on the inner surface of the upper cross section of the pipe, and a line indicated by a triangular point indicates the stress generated on the outer surface.
[0034]
As can be seen from the figure, the stress generated on the inner surface decreases as the diameter reduction rate increases from 0, that is, as the diameter of the pipe end decreases. However, the stress generated on the inner surface from the point when the diameter reduction ratio exceeds about 80% increases conversely. That is, it can be seen that if the diameter of the end portion is too small, the stress reduction effect is reduced. Therefore, if only the inner surface side is taken into consideration, it is preferable that the diameter reduction ratio of the end portion is about 80%. However, as can be seen from the figure, the stress generated on the outer surface increases proportionally as the diameter reduction ratio at the end increases. In order to balance the stress generated on the inner surface and the outer surface and optimally improve the overall strength of the joint portion 5, the present inventors need to set the diameter reduction ratio within a range of 20 to 50%. confirmed. That is, when the diameter reduction ratio is within this range, the stress generated on the inner surface can be sufficiently reduced, and the stress generated on the outer surface is not excessively increased, resulting in an optimal balance. Therefore, in the axle case of the present embodiment as shown in FIG. 1, the difference between the diameter of the joint end 1 of the main body 38 and the diameter of the adjacent portion 4 is 20 with respect to the plate thickness T of the joint end 1. It is preferable to be in the range of ˜50%.
[0035]
Furthermore, the present inventors have confirmed that the length L of the joining end 1 shown in FIG. 1 is preferably in the range of 1 to 2 times the plate thickness T of the joining end 1. That is, if the length L of the joint end 1 is too short, it becomes difficult to form the main body 38 (upper and lower members 30, 31). If too long, the local moment M3 acting on the joint 5 (see FIG. 3). ) Is reduced, the stress reduction effect is reduced.
[0036]
In the above-described reference embodiment, the example in which the joint end 1 of the main body 38 is reduced in diameter has been described. However, the embodiment of the present invention is based on the same concept, as shown in FIG. The diameter of the portion 2 is reduced with respect to the adjacent portion 10 , or the joint ends 1 and 2 of both the main body 38 and the spindle 33 are reduced in diameter as shown in FIG. Is . Also in these forms, the same effect as the form shown in FIG. 1 can be obtained.
[0037]
Further, according to the present invention, it is not always necessary to reduce the diameter of the joint ends 1 and 2 of the main body 38 and / or the spindle 33 over the entire circumference. In other words, as explained in the section of “Prior Art”, the moment acting on the axle case often acts in the vertical direction, so that at least the vertical direction of the joint ends 1 and 2 of the main body 38 and / or the spindle 33. May be made smaller than the vertical dimension of the adjacent portions 4 and 10 continuous to the joint end portions 1 and 2. In that case, the main body 38 and / or the spindle 33 may be fitted into a mold and compressed (pressed) in the vertical direction to shorten only the vertical dimension without changing the horizontal dimension. Alternatively, the main body 38 and / or the spindle 33 may be simply crushed from the vertical direction and formed into a substantially elliptical shape. When the main body 38 and / or the spindle 33 are simply crushed and molded, a mold or the like is not required, and therefore it can be provided at a lower cost. These processes may be performed before or after the main body 38 and the spindle 33 are bonded.
[0038]
So far, it has been described that the joint ends 1 and 2 of the main body 38 and / or the spindle 33 are reduced in diameter relative to the adjacent portions 4 and 10, but conversely, the adjacent portion of the main body 38 and / or the spindle 33. Of course, the diameter may be increased by 4 or 10.
[0039]
【The invention's effect】
In short, according to the present invention, an excellent effect is achieved in that the strength of the joint portion between the main body and the spindle can be improved simply and at low cost.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of an upper joint portion between a main body and a spindle in an axle case according to a reference embodiment that is not an embodiment of the present invention.
2 is a perspective view showing a joint portion between a main body and a spindle in the axle case of FIG. 1. FIG.
FIG. 3 is an explanatory diagram for explaining a stress generated in a joint portion between a main body and a spindle.
FIG. 4A shows the tensile stress generated at the joint between the main body and the spindle.
(B) has shown the stress which generate | occur | produces in a junction part by the local moment which acts on the junction part of a main body and a spindle.
(C) shows the stress generated at the joint between the main body and the spindle.
FIG. 5 is a graph showing the relationship between the diameter reduction rate of the pipe end and the stress generated on the outer surface and the inner surface of the upper cross section of the pipe.
FIG. 6A is an enlarged cross-sectional view of an upper joint portion between a main body and a spindle in an axle case according to an embodiment of the present invention.
(B) is an expanded sectional view of the upper joined part of a main part and a spindle in an axle case of other embodiments of the present invention.
FIG. 7 is a front view of an axle case.
FIG. 8 is an enlarged cross-sectional view of an upper joint portion between a main body and a spindle in a conventional axle case.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 Joining ends 4,10 Adjacent part 5 Joining part 30 Upper member 31 Lower member 33 Spindle 38 Main body

Claims

Consists of an upper member and a lower member that are joined one above the other in the vertical direction, and a main body in which both ends in the longitudinal direction are formed in a substantially cylindrical shape, and the two ends in the longitudinal direction of the main body are each butted from the outer peripheral side. An axle case with a substantially cylindrical spindle,
The spindle has a substantially cylindrical joint end said body are welded against an inclined portion that is gradually enlarged toward the connecting formed vehicle width direction outer side to the bonding end portion, the inclined And having a substantially cylindrical adjacent portion having a diameter larger than that of the joining end portion,
The difference between the vertical dimension of the adjacent part and the vertical dimension of the joint end part is within a range of 20 to 50% of the plate thickness of the joint end part,
An axle case, wherein a length from a boundary between the inclined portion and the joining end portion to an end face of the joining end portion is within a range of 1 to 2 times a plate thickness of the joining end portion.

Consists of an upper member and a lower member that are joined one above the other in the vertical direction, and a main body in which both ends in the longitudinal direction are formed in a substantially cylindrical shape, and the two ends in the longitudinal direction of the main body are each butted from the outer peripheral side. An axle case with a substantially cylindrical spindle,
The main body includes a substantially cylindrical joint end portion to which the spindle is abutted and welded, an inclined portion formed so as to be connected to the joint end portion and gradually enlarged in the vehicle width direction, and the inclined portion. And having a substantially cylindrical adjacent portion having a diameter larger than that of the joining end portion,
The spindle includes a substantially cylindrical joint end portion to which the main body is abutted and welded, an inclined portion formed to be connected to the joint end portion and gradually expanded in the vehicle width direction, and the inclined portion. And having a substantially cylindrical adjacent portion having a diameter larger than that of the joining end portion,
The difference between the vertical dimension of the adjacent part of the main body and the vertical dimension of the joint end part of the main body is within a range of 20 to 50% of the plate thickness of the joint end part of the main body, and the adjacent part of the spindle The vertical dimension of the spindle and the vertical dimension of the joint end of the spindle are within a range of 20 to 50% of the thickness of the joint end of the spindle ,
The length from the boundary between the inclined portion of the main body and the joint end of the main body to the end face of the joint end of the main body is within a range of 1 to 2 times the plate thickness of the joint end of the main body, The length from the boundary between the inclined part of the spindle and the joining end of the spindle to the end surface of the joining end of the spindle is in the range of 1 to 2 times the plate thickness of the joining end of the spindle. Axle case characterized by.