JP4171658B2 - Breaking and splitting method for connecting rod - Google Patents

Breaking and splitting method for connecting rod Download PDF

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Publication number
JP4171658B2
JP4171658B2 JP2003032610A JP2003032610A JP4171658B2 JP 4171658 B2 JP4171658 B2 JP 4171658B2 JP 2003032610 A JP2003032610 A JP 2003032610A JP 2003032610 A JP2003032610 A JP 2003032610A JP 4171658 B2 JP4171658 B2 JP 4171658B2
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Prior art keywords
groove
fracture
starting
connecting rod
large end
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JP2004245237A (en
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毅巳 菅原
善次 飯田
健太郎 高田
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Honda Motor Co Ltd
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Honda Motor Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C7/00—Connecting-rods or like links pivoted at both ends; Construction of connecting-rod heads
    • F16C7/02—Constructions of connecting-rods with constant length
    • F16C7/023—Constructions of connecting-rods with constant length for piston engines, pumps or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C9/00—Bearings for crankshafts or connecting-rods; Attachment of connecting-rods
    • F16C9/04—Connecting-rod bearings; Attachments thereof
    • F16C9/045—Connecting-rod bearings; Attachments thereof the bearing cap of the connecting rod being split by fracturing

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  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車用エンジン部品のコネクティングロッドの破断分割加工方法に係り、特に、破断分割面において段差発生を防止するための加工技術に関する。
【０００２】
【従来の技術】
自動車用エンジン部品であるコネクティングロッドは、クランクピンに連結される大端部側と、ピストンピンに連結される小端部側とからなり、破断分割を行う場合には、通常、鍛造成形、鋳造成形又は焼結成形した後に、所定部分に機械加工が施されるとともに、大端部側の連結孔部分がキャップ部とロッド部とに分割される。
【０００３】
このようなコネクティングロッドの破断分割加工方法については、鍛造段階で大端部の破断分割予定部位の端面及び／又は側面にＶ形またはＵ形の溝を形成し、バリ取り鍛造段階でこの溝を両側から肉寄せ鍛造して鍛造欠陥をノッチとして残こし、その後破断分割予定部位に対して破断分割を施す技術が提案されている（例えば、特許文献１参照。）。
【０００４】
【特許文献１】
特開平１１−４４３１６号公報（第３頁左欄、第３−６図）
【０００５】
【発明が解決しようとする課題】
しかしながら、上記特許文献１に記載された技術にしたがい、図１に示す大端部１１と小端部１２とを備えるコネクティングロッドにノッチ１３，１４を形成して破断分割を行った場合には、同図に示すように、大端部１１の上下両面に形成されたノッチ１３，１４からそれぞれ破断分割が開始される。この破断は、コネクティングロッド材料のミクロ的な強度差に基づき、相対的に強度が低い部位に進行し易い。このため、各ノッチ１３，１４から発生して徐々に内部に進行する破断面が最終的に合体する最終破断部においては、各ノッチ１３，１４から生じた二つの破断面が不連続部分を形成して、段差を生ずるおそれがある。このように破断分割時に段差が生じた場合には、使用時にキャップ部１５とロッド部１６とをボルトにより締結した際、キャップ部１５とロッド部１６との間に相当の応力が負荷されると、上記段差部分で欠けが生じ易く、ときには応力集中によって段差部分を起点とした割れが発生することもある。したがって、ボルト締結時に上記欠けや割れの発生を防止すべく、破断分割時の最終破断部において段差が生じないコネクティングロッドの加工技術の開発が要請されていた。
【０００６】
本発明は、このような要請に鑑みてなされたものであり、破断分割時の最終破断部において段差が生じないコネクティングロッドの破断分割加工方法を提供することを目的としている。
【０００７】
【課題を解決するための手段】
本発明は、大端部と小端部とを備えるコネクティングロッドを一体成形し、一体成形時または一体成形後にボルト孔を設けるとともに、大端部の破断分割部の内周面側にに破断分割の起点となる起点溝を設け、大端部の破断分割部の端面側に前記起点溝と連通して破断分割の進行を誘導する誘導溝を設け、その後大端部を破断分割するコネクティングロッドの破断分割加工方法であって、起点溝と誘導溝の断面はＶ字状をなし、起点溝の切込み角度は誘導溝の切込み角度よりも小さく、起点溝の深さは誘導溝の深さよりも深いことを特徴としている。ここで、本発明では、起点溝と誘導溝の断面がＵ字状をなす場合には、起点溝の底部の曲率半径は誘導溝の底部の曲率半径よりも小さく、起点溝の深さは誘導溝の深さよりも深い。
【０００８】
本発明のコネクティングロッドの破断分割加工方法では、破断分割時に、分割の起点となる起点溝から破断分割が開始されるとともに、起点溝と連通する誘導溝が破断分割を誘導するように、破断分割が進行する。このため、破断が完了する最終破断部においては、複数の破断面が不連続部分となって段差が形成されることはない。これは、起点溝と誘導溝とが離間せずに連通しているため、起点溝を起点として一方向にしかも連続的に破断分割が進行するためである。したがって、本発明によれば、ボルト締結時に段差による欠けや割れの発生を防止することができる。なお、起点溝および誘導溝の形状はＵ字溝またはＶ字溝のいずれかである。例えば、これらの溝を全てＵ字溝とする場合には、誘導溝に比して起点溝の曲率半径を小さく設定する。これにより、分割時に破断分割が起点溝から速やかに行われる。またその深さを大きく設定するとさらに効果的である。これに対し、上記溝を全てＶ字溝とする場合には、誘導溝に比して起点溝の切込み角度を鋭角に設定する。これにより、分割時に破断分割が起点溝から速やかに行われる。またその深さを大きく設定するとさらに効果的である。
【０００９】
このようなコネクティングロッドの破断分割加工方法においては、上記起点溝と上記誘導溝とにより破断分割面を取り囲むことが望ましい。このような構成を採用した場合には、上述したように、起点溝から破断分割が開始され、この起点溝と連通する誘導溝が破断分割を誘導するように破断分割が進行する。そして、全体で環状をなす起点溝と誘導溝とからなる溝全体を起点溝の両側から一周するように、誘導溝の起点溝から最も離間した部位まで破断分割が進行し、この部位を最終破断部として破断分割が完了する。この場合には、最終破断部にも起点溝から連通した誘導溝が設けられていることから、複数の破断面が不連続的に合体する箇所が出現し得ないだけでなく、最終破断面に誘導溝が設けられているために最終破断面近傍が平滑となり、このため破断分割面を全体としてより平滑にすることができる。このため、ボルト締結時に、たとえボルト孔付近の破断面付近に応力集中が生じた場合であっても、割れ等の欠陥の発生を十分に防止することができる。
【００１０】
また、このようなコネクティングロッドの破断分割加工方法においては、上記ボルト孔の内壁面に補助溝を設けることが望ましい。ボルト孔の内壁面には破断分割する前に機械加工が予め施されるのが一般的である。このため、ボルト孔の内壁面近傍では、鍛造後破断分割前に機械加工がなされない大端部外周面近傍に比して、材料のミクロ的な強度差による破断分割の低強度部位への進行が生じ易く、結果的に破断分割を所定の方向に進行させることが困難である。ボルト孔の内壁面近傍で所定の破断分割が実現されない場合には、ボルト孔の内壁面における破断部において段差が生ずる。そして、破断分割がさらに進行すると、この段差に応じて、大端部の外表面に現れる最終破断部にも段差が生ずる。この最終破断部に生じた段差は、上述したようにボルト締結時に生ずる欠けや割れの発生原因となるものである。本発明では、ボルト孔の内壁面に補助溝を設けていることから、破断分割が進行して破断面が補助溝の起点溝から最も近い部位に到達すると、補助溝に沿って破断分割が進行するため、ボルト孔の内壁面における破断部において複数の破断面が不連続部分となって段差が形成されることはない。よって、破断分割がさらに進行すると、誘導溝の作用の下、上記破断部の好適な破断面に応じて、大端部の外表面においても段差のない好適な破断面が現れる。したがって、本発明によれば、ボルト締結時に欠けや割れの発生を十分に防止することができる。
【００１１】
【発明の実施の形態】
以下に、本発明の実施形態を図面を参照して説明する。
図２は、本発明の好適な一の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図を、（ｂ）は破断分割後のキャップ部の破断部付近の斜視図をそれぞれ示す。大端部１と小端部（図示せず）とが一体成形されたコネクティングロッドには、図２（ａ）に示すように、破断分割前にボルト孔２が形成されるとともに、大端部１の破断分割部において、大端部１の内周面側には破断分割の起点となる起点溝３が形成され、スラスト部には起点溝３の両端からそれぞれ連通して破断分割の進行を誘導する誘導溝４ａ，４ｂが形成される。起点溝３および誘導溝４ａ，４ｂの形状はＵ字溝またはＶ字溝のいずれとすることもできる。例えば、これらの溝３，４ａ，４ｂをＵ字溝とする場合には、分割時に破断分割が起点溝３から速やかに行われるように、誘導溝４ａ，４ｂに比して起点溝３の曲率半径を小さく、またその深さを大きく設定することが必要である。これに対し、上記溝３，４ａ，４ｂをＶ字溝とする場合には、上記の理由により、誘導溝４ａ，４ｂに比して起点溝３の切込み角度を鋭角に、またその深さを大きく設定することが必要である。なお、破断分割の形態は、従来から公知のものであれば、いかなる形態のものを使用することもでき、例えば、落球式による形態でも、油圧シリンダ式による形態であってもよい。
【００１２】
このような連通する起点溝３および誘導溝４ａ，４ｂを形成したことにより、破断分割は、図２（ｂ）に示すように、起点溝３から矢印の方向に連続的に進行し、誘導溝４ａ，４ｂによる誘導の下、最終的には大端部の外周面５にて完了する。このため、破断が完了する最終破断部（外周面５）においては、複数の破断面が不連続部分となって段差が形成されることはない。したがって、図２による実施形態によれば、ボルト締結時に段差による欠けや割れの発生を防止することができる。
【００１３】
図３は、本発明の好適な他の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図を、（ｂ）は破断分割後のキャップ部の破断部付近の斜視図をそれぞれ示す。図３に示す例においても、破断分割前には、図２に示す例と同様に、ボルト孔２と起点溝３および誘導溝４ａ，４ｂとが形成される。さらに、本例では、誘導溝４ａ，４ｂの各端部と連通する誘導溝４ｃが大端部の外周面に形成され、起点溝３，誘導溝４ａ，４ｂ，４ｃにより破断分割面が包囲される。なお、各溝３，４ａ，４ｂ，４ｃの溝形状、曲率半径、切り込み角度および深さ、ならびに破断分割の形態は、図２に示す例におけるものと同様とすることができる。
【００１４】
このような連通する起点溝３および誘導溝４を形成されたことにより、破断分割は、図３（ｂ）に示すように、起点溝３から矢印の方向に連続的に進行する。すなわち、破断分割は、誘導溝４ａ，４ｂ，４ｃによる誘導の下、全体で環状をなす起点溝３と誘導溝４とからなる溝全体を起点溝３の両側から取り囲むように、誘導溝４の起点溝から最も離間した部位まで破断分割が進行し、この部位を最終破断部として破断分割が完了する。このため、破断が完了する最終破断部（外周面５）においては、複数の破断面が不連続部分となって段差が形成されることはない。また、誘導溝４ｃが最終破断部を平滑とするため、破断分割面を全体としてより平滑にすることができる。したがって、図３による実施形態によれば、ボルト締結時に、たとえボルト孔付近の破断面付近に応力集中が生じた場合であっても、割れ等の欠陥の発生を十分に防止することができる。
【００１５】
図４は、本発明の好適な他の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図を、（ｂ）は破断分割後のキャップ部の破断部付近の斜視図をそれぞれ示す。破断分割前には、図２に示す例と同様に、ボルト孔２と起点溝３および誘導溝４ａ，４ｂとが形成される。さらに、本例では、破断分割前にボルト孔中の分割破断仮想部にシャンクにより補助溝６が形成される。なお、各溝３，４ａ，４ｂの溝形状、曲率半径、切り込み角度および深さ、ならびに破断分割の形態は図２に示す例におけるものと同様とすることができる。
【００１６】
このような連通する起点溝３および誘導溝４を形成されたことにより、破断分割は、図４（ｂ）に示すように、起点溝３から矢印の方向に連続的に進行する。すなわち、破断分割は、誘導溝４ａ，４ｂによる誘導の下、破断面が補助溝６の起点溝３から最も近い部位に到達すると、補助溝６に沿って破断分割が進行するため、ボルト孔２の内壁面における破断部において段差は生じない。よって、破断分割がさらに進行すると、誘導溝４ａ，４ｂの誘導作用の下、ボルト孔２の内壁面における破断部の好適な破断面に応じて、大端部の外周面５においても段差のない好適な破断面が現れる。したがって、本発明によれば、ボルト締結時に欠けや割れの発生を十分に防止することができる。
【００１７】
【発明の効果】
以上説明したように、本発明によれば、コネクティングロッドの大端部の破断分割部に破断分割の起点となる起点溝と、起点溝と連通して破断分割の進行を誘導する誘導溝とを設けて大端部を破断分割することで、ボルト締結時に段差による欠けや割れの発生を防止することができる。よって本発明は、自動車用エンジン部品のコネクティングロッドに対する好適な破断分割加工方法を提供することができる点で好ましい。
【図面の簡単な説明】
【図１】 従来のコネクティングロッドの破断分割加工方法を示す側面図である。
【図２】 本発明の好適な一の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図であり、（ｂ）は破断分割後のキャップ部の破断部付近の斜視図である。
【図３】 本発明の好適な他の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図であり、（ｂ）は破断分割後のキャップ部の破断部付近の斜視図である。
【図４】 本発明の好適な他の実施形態におけるコネクティングロッドを示し、同図中（ａ）は破断分割前の大端部の破断部付近の斜視図であり、（ｂ）は破断分割後のキャップ部の破断部の斜視図である。
【符号の説明】
１…大端部、２…ボルト孔、３…起点溝、４，４ａ，４ｂ…誘導溝、５…外周面。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fracture split processing method for a connecting rod of an automotive engine part, and more particularly to a processing technique for preventing the occurrence of a step on a fracture split surface.
[0002]
[Prior art]
Connecting rods, which are automotive engine parts, consist of a large end connected to the crankpin and a small end connected to the piston pin. After molding or sintering, the predetermined portion is machined, and the connecting hole portion on the large end side is divided into a cap portion and a rod portion.
[0003]
With respect to such a fracture splitting method for connecting rods, a V-shaped or U-shaped groove is formed on the end face and / or the side surface of the large fracture end portion at the forging stage, and this groove is formed at the deburring forging stage. A technique has been proposed in which forging defects are left as a notch from both sides and a forging defect is left as a notch, and then a fracture division is performed on a planned fracture division site (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-44316 (left column of page 3, FIG. 3-6)
[0005]
[Problems to be solved by the invention]
However, in accordance with the technique described in Patent Document 1, when the notch 13 and 14 are formed in the connecting rod having the large end portion 11 and the small end portion 12 shown in FIG. As shown in the figure, the fracture division is started from notches 13 and 14 formed on the upper and lower surfaces of the large end portion 11. This rupture tends to proceed to a relatively low strength portion based on the microscopic strength difference of the connecting rod material. For this reason, in the final fractured portion where the fractured surfaces generated from the notches 13 and 14 and gradually proceeding to the inside finally merge, the two fractured surfaces generated from the notches 13 and 14 form discontinuous portions. As a result, there is a risk of producing a step. In this way, when a step is generated at the time of fracture division, when the cap portion 15 and the rod portion 16 are fastened with bolts during use, a considerable stress is applied between the cap portion 15 and the rod portion 16. Cracks are likely to occur at the step portion, and sometimes cracks are generated from the step portion due to stress concentration. Therefore, in order to prevent the occurrence of the above-mentioned chipping and cracking at the time of bolt fastening, there has been a demand for the development of a processing technique for a connecting rod that does not cause a step at the final fracture portion at the time of fracture division.
[0006]
The present invention has been made in view of such a demand, and an object of the present invention is to provide a fracture splitting method for a connecting rod in which a step does not occur at the final fracture portion at the time of fracture split.
[0007]
[Means for Solving the Problems]
The present invention integrally forms a connecting rod having a large end portion and a small end portion, and provides a bolt hole at the time of integral molding or after integral molding , and breaks and splits on the inner peripheral surface side of the fracture end portion of the large end portion. Of a connecting rod that is provided with a starting groove that serves as a starting point, and that is provided with a guiding groove that communicates with the starting groove to guide the progress of the breaking division on the end face side of the breaking end portion of the large end portion, and then breaks and breaks the large end portion . In this fracture splitting method, the starting groove and the guiding groove have a V-shaped cross section, the cutting angle of the starting groove is smaller than the cutting angle of the guiding groove, and the depth of the starting groove is deeper than the depth of the guiding groove. It is characterized by that. Here, in the present invention, when the cross section of the starting groove and the guiding groove is U-shaped, the radius of curvature of the bottom of the starting groove is smaller than the radius of curvature of the bottom of the guiding groove, and the depth of the starting groove is guided. Deeper than the depth of the groove.
[0008]
In the fracture splitting method for a connecting rod according to the present invention, at the time of fracture splitting, fracture splitting is started so that fracture splitting is started from a starting groove serving as a starting point of splitting, and a guide groove communicating with the starting groove guides fracture splitting. Progresses. For this reason, in the final fracture | rupture part which a fracture | rupture completes, a several step surface becomes a discontinuous part, and a level | step difference is not formed. This is because the starting groove and the guiding groove communicate with each other without being separated from each other, so that the fracture split proceeds continuously in one direction starting from the starting groove. Therefore, according to the present invention, it is possible to prevent the occurrence of chipping or cracking due to a step during bolt fastening. The shape of the starting point groove and guide groove are either U-shaped groove or V-groove. For example, the case where all these grooves U-shaped groove, is set small the curvature radius of the starting point groove than the guide groove. Thereby , the fracture | rupture division | segmentation is performed rapidly from a starting groove | channel at the time of a division | segmentation . It is more effective to set the depth large . On the other hand, when all the grooves are V-shaped grooves, the cutting angle of the starting groove is set to an acute angle as compared to the guide groove. Thereby, the fracture | rupture division | segmentation is performed rapidly from a starting groove | channel at the time of a division | segmentation. It is more effective to set the depth large.
[0009]
In such a fracture splitting method for connecting rods, it is desirable to surround the fracture split surface by the starting groove and the guide groove. In the case of adopting such a configuration, as described above, the fracture division is started from the starting groove, and the fracture division proceeds so that the guide groove communicating with the starting groove induces the fracture division. Then, the fracture split proceeds to the part farthest from the starting groove of the guide groove so that the entire groove composed of the starting groove and the guiding groove that form a ring as a whole makes a round from both sides of the starting groove, and this part is finally broken. The breaking division is completed as a part. In this case, since the guide groove communicated from the starting groove is also provided in the final fracture portion, not only the location where a plurality of fracture surfaces discontinuously merge cannot appear, but also in the final fracture surface. Since the guide groove is provided, the vicinity of the final fracture surface becomes smooth, and therefore the fracture split surface can be made smoother as a whole. For this reason, even when the stress concentration occurs near the fracture surface near the bolt hole at the time of bolt fastening, it is possible to sufficiently prevent the occurrence of defects such as cracks.
[0010]
In such a connecting rod fracture splitting method, it is desirable to provide an auxiliary groove on the inner wall surface of the bolt hole. Generally, the inner wall surface of the bolt hole is preliminarily machined before being broken and divided. For this reason, in the vicinity of the inner wall surface of the bolt hole, the fracture split progresses to a low strength part due to the difference in microscopic strength of the material, compared with the vicinity of the outer peripheral surface of the large end which is not machined before fracture split after forging. As a result, it is difficult to cause breakage division to proceed in a predetermined direction. When the predetermined fracture division is not realized in the vicinity of the inner wall surface of the bolt hole, a step is generated at the fracture portion on the inner wall surface of the bolt hole. Then, when the fracture splitting further proceeds, a step is generated in the final fracture portion that appears on the outer surface of the large end portion according to the level difference. As described above, the level difference generated in the final fracture portion is a cause of chipping or cracking that occurs during bolt fastening. In the present invention, since the auxiliary groove is provided on the inner wall surface of the bolt hole, the fracture split proceeds along the auxiliary groove when the fracture split progresses and the fracture surface reaches the portion closest to the starting groove of the auxiliary groove. Therefore, a plurality of fractured surfaces become discontinuous portions at the fractured portion on the inner wall surface of the bolt hole, and no step is formed. Therefore, when the fracture splitting further proceeds, a suitable fracture surface having no step appears on the outer surface of the large end portion according to the preferred fracture surface of the fracture portion under the action of the guide groove. Therefore, according to the present invention, it is possible to sufficiently prevent the occurrence of chipping and cracking during bolt fastening.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
2A and 2B show a connecting rod according to a preferred embodiment of the present invention, in which FIG. 2A is a perspective view of the vicinity of the fractured portion of the large end portion before fracture splitting, and FIG. 2B is a diagram after fracture splitting. The perspective view near the fracture | rupture part of a cap part is shown, respectively. In the connecting rod in which the large end 1 and the small end (not shown) are integrally formed, as shown in FIG. 2 (a), a bolt hole 2 is formed before the fracture split, and the large end In one fracture split portion, a starting groove 3 serving as a starting point of the fracture split is formed on the inner peripheral surface side of the large end portion 1, and the fracture split is progressed through the thrust portion from both ends of the starting groove 3. Guiding grooves 4a and 4b for guiding are formed. The shape of the starting groove 3 and the guide grooves 4a and 4b can be either a U-shaped groove or a V-shaped groove. For example, when these grooves 3, 4 a, 4 b are U-shaped grooves, the curvature of the starting groove 3 compared to the guiding grooves 4 a, 4 b is such that the fracture split is performed quickly from the starting groove 3 during the division. It is necessary to set a small radius and a large depth. On the other hand, when the grooves 3, 4a, 4b are V-shaped grooves, the cutting angle of the starting groove 3 is set to an acute angle and the depth thereof as compared with the guide grooves 4a, 4b. It is necessary to set a large value. Note that any form of breaking division can be used as long as it is conventionally known. For example, a falling ball type or a hydraulic cylinder type may be used.
[0012]
By forming the starting groove 3 and the guiding grooves 4a and 4b that communicate with each other, the fracture split proceeds continuously from the starting groove 3 in the direction of the arrow as shown in FIG. Under the guidance by 4a and 4b, the process is finally completed on the outer peripheral surface 5 at the large end. For this reason, in the last fracture | rupture part (outer peripheral surface 5) where a fracture | rupture is completed, a several level | step fracture surface becomes a discontinuous part, and a level | step difference is not formed. Therefore, according to the embodiment shown in FIG. 2, it is possible to prevent the occurrence of chipping or cracking due to a step during bolt fastening.
[0013]
FIG. 3 shows a connecting rod according to another preferred embodiment of the present invention, in which (a) is a perspective view of the vicinity of the fractured portion of the large end portion before fracture division, and (b) is a diagram after fracture division. The perspective view near the fracture | rupture part of a cap part is shown, respectively. Also in the example shown in FIG. 3, the bolt hole 2, the starting groove 3, and the guide grooves 4 a and 4 b are formed in the same manner as in the example shown in FIG. 2 before the fracture division. Further, in this example, a guide groove 4c communicating with each end portion of the guide grooves 4a and 4b is formed on the outer peripheral surface of the large end portion, and the fracture split surface is surrounded by the starting groove 3 and the guide grooves 4a, 4b and 4c. The In addition, the groove shape, curvature radius, cutting angle and depth of each groove 3, 4a, 4b, and 4c, and the form of fracture division can be the same as those in the example shown in FIG.
[0014]
By forming the starting groove 3 and the guiding groove 4 that communicate with each other, the fracture division proceeds continuously from the starting groove 3 in the direction of the arrow as shown in FIG. That is, the breaking division is performed by guiding the guide groove 4 so as to surround the entire groove including the starting groove 3 and the guiding groove 4 that form an annular shape as a whole under the guidance of the guiding grooves 4a, 4b, and 4c. The fracture division proceeds to the most distant portion from the starting groove, and the fracture division is completed with this portion as the final fracture portion. For this reason, in the last fracture | rupture part (outer peripheral surface 5) where a fracture | rupture is completed, a several level | step fracture surface becomes a discontinuous part, and a level | step difference is not formed. Further, since the guide groove 4c smoothes the final fracture portion, the fracture split surface can be made smoother as a whole. Therefore, according to the embodiment shown in FIG. 3, even when stress concentration occurs near the fracture surface near the bolt hole at the time of fastening the bolt, it is possible to sufficiently prevent the occurrence of defects such as cracks.
[0015]
4A and 4B show a connecting rod according to another preferred embodiment of the present invention, in which FIG. 4A is a perspective view of the vicinity of the fractured portion of the large end portion before fracture splitting, and FIG. 4B is a diagram after fracture splitting. The perspective view near the fracture | rupture part of a cap part is shown, respectively. Before the splitting, the bolt hole 2, the starting groove 3, and the guide grooves 4a and 4b are formed as in the example shown in FIG. Furthermore, in this example, the auxiliary groove 6 is formed by the shank in the divided fracture virtual part in the bolt hole before the fracture division. The groove shape, the radius of curvature, the cutting angle and depth, and the form of fracture division of each groove 3, 4a, 4b can be the same as those in the example shown in FIG.
[0016]
Due to the formation of the starting groove 3 and the guiding groove 4 that communicate with each other, the fracture split proceeds continuously from the starting groove 3 in the direction of the arrow as shown in FIG. That is, when the fracture splitting is guided by the guide grooves 4a and 4b and the fracture surface reaches the portion closest to the starting groove 3 of the auxiliary groove 6, the fracture split proceeds along the auxiliary groove 6, so that the bolt hole 2 No step occurs at the fractured portion of the inner wall surface. Therefore, when the break splitting further proceeds, there is no step on the outer peripheral surface 5 of the large end portion according to the suitable fracture surface of the fracture portion on the inner wall surface of the bolt hole 2 under the guiding action of the guide grooves 4a and 4b. A suitable fracture surface appears. Therefore, according to the present invention, it is possible to sufficiently prevent the occurrence of chipping and cracking during bolt fastening.
[0017]
【The invention's effect】
As described above, according to the present invention, the breaking groove at the large end portion of the connecting rod is provided with a starting groove serving as a starting point of the breaking split, and a guide groove that communicates with the starting groove and guides the progress of the breaking split. By providing and dividing the large end portion by breakage, it is possible to prevent chipping or cracking due to a step during bolt fastening. Therefore, this invention is preferable at the point which can provide the suitable fracture | rupture division processing method with respect to the connecting rod of the engine parts for motor vehicles.
[Brief description of the drawings]
FIG. 1 is a side view showing a conventional fracture splitting method for a connecting rod.
FIG. 2 shows a connecting rod according to a preferred embodiment of the present invention, in which (a) is a perspective view of the vicinity of the fractured portion of the large end before fracture splitting, and (b) is after fracture splitting. It is a perspective view near the fracture | rupture part of a cap part.
FIG. 3 shows a connecting rod according to another preferred embodiment of the present invention, in which (a) is a perspective view of the vicinity of the fractured portion of the large end before fracture splitting, and (b) is after fracture splitting. It is a perspective view near the fracture | rupture part of a cap part.
FIG. 4 shows a connecting rod according to another preferred embodiment of the present invention, in which (a) is a perspective view of the vicinity of the fractured portion of the large end portion before fracture splitting, and (b) is after fracture splitting. It is a perspective view of the fracture | rupture part of a cap part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Large end part, 2 ... Bolt hole, 3 ... Origin groove | channel, 4, 4a, 4b ... Guide groove, 5 ... Outer peripheral surface.

Claims (4)

大端部と小端部とを備えるコネクティングロッドを一体成形し、一体成形時または一体成形後にボルト孔を設けるとともに、大端部の破断分割部の内周面側にに破断分割の起点となる起点溝を設け、大端部の破断分割部の端面側に前記起点溝と連通して破断分割の進行を誘導する誘導溝を設け、その後大端部を破断分割するコネクティングロッドの破断分割加工方法であって、前記起点溝と前記誘導溝の断面はＶ字状をなし、前記起点溝の切込み角度は前記誘導溝の切込み角度よりも小さく、前記起点溝の深さは前記誘導溝の深さよりも深いことを特徴とするコネクティングロッドの破断分割加工方法。Integrally molded connecting rod and a big end and a small end, becomes provided with a molded during or bolt holes after integral molding, the starting point of fracture split into the inner peripheral surface side of the fracture splitting of the large end the starting point groove is provided, through the starting point groove and with the end surface side of the fracture splitting of the large end of the guide groove for guiding the progress of the fracture splitting provided, breakage of the then Turkey next-coating rod to fracture splitting the big end In the split machining method , a cross section of the starting groove and the guiding groove is V-shaped, a cutting angle of the starting groove is smaller than a cutting angle of the guiding groove, and a depth of the starting groove is the guiding groove. A method for breaking and dividing a connecting rod, characterized by being deeper than the depth of the connecting rod. 大端部と小端部とを備えるコネクティングロッドを一体成形し、一体成形時または一体成形後にボルト孔を設けるとともに、大端部の破断分割部の内周面側に破断分割の起点となる起点溝を設け、大端部の破断分割部の端面側に前記起点溝と連通して破断分割の進行を誘導する誘導溝を設け、その後大端部を破断分割するコネクティングロッドの破断分割加工方法であって、前記起点溝と前記誘導溝の断面はＵ字状をなし、前記起点溝の底部の曲率半径は前記誘導溝の底部の曲率半径よりも小さく、前記起点溝の深さは前記誘導溝の深さよりも深いことを特徴とするコネクティングロッドの破断分割加工方法。A connecting rod having a large end and a small end is integrally formed, and a bolt hole is provided at the time of integral molding or after integral molding, and a starting point that is a starting point for fracture splitting on the inner peripheral surface side of the fracture splitting part at the large end A connecting rod fracture splitting method in which a groove is provided, a guide groove is provided on the end face side of the fracture end portion of the large end portion so as to communicate with the starting groove and guide the progress of the fracture splitting, and then the large end portion is fractured and split. The starting groove and the guiding groove have a U-shaped cross section, the radius of curvature of the bottom of the starting groove is smaller than the radius of curvature of the bottom of the guiding groove, and the depth of the starting groove is the guiding groove. A method for breaking and dividing a connecting rod, characterized by being deeper than the depth of the connecting rod. 前記誘導溝を前記大端部の外周面側にも設けることにより、前記起点溝と前記誘導溝とにより破断分割面を取り囲むことを特徴とする請求項１または２に記載のコネクティングロッドの破断分割加工方法。The fracture splitting of the connecting rod according to claim 1 or 2 , wherein the guide groove is provided also on the outer peripheral surface side of the large end portion so that the fracture split surface is surrounded by the starting groove and the guide groove. Processing method. 前記ボルト孔の内壁面に、円周方向に延在する補助溝を破断分割面上に設けることを特徴とする請求項１〜３のいずれかに記載のコネクティングロッドの破断分割加工方法。Wherein the inner wall surface of the bolt holes, fracture splitting processing method of a connecting rod according to any one of claims 1-3, characterized in that an auxiliary groove extending circumferentially on the fracture splitting surface.
JP2003032610A 2003-02-10 2003-02-10 Breaking and splitting method for connecting rod Expired - Fee Related JP4171658B2 (en)

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WO2006051822A1 (en) * 2004-11-09 2006-05-18 Honda Motor Co., Ltd. Device and method for inspecting connecting rod
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JP2009127696A (en) * 2007-11-21 2009-06-11 Toyota Industries Corp Connecting rod and its manufacturing method
CN102725100B (en) * 2011-01-24 2015-08-12 丰田自动车株式会社 The method for breaking of connecting rod
DE102012112539A1 (en) * 2012-03-12 2013-09-12 Mauser-Werke Oberndorf Maschinenbau Gmbh Method and device for fracture separation of a workpiece
JP2014142004A (en) * 2013-01-23 2014-08-07 Univ Of Hyogo Method of processing aluminum alloy die cast split-type connecting rod
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