CRANK SHAFT MANUFACTURING METHOD

• Main Authors: TAMURA KENJI, YABUNO KUNIHIRO, OKUBO JUNICHI, NAKANO RYUSUKE, OTA YUKIHIRO
• Format: Patent
• Language: English; Japanese
• Published: 19.04.2022
• Subjects: BEARINGS; BLASTING; ELEMENTS OR CRANKSHAFT MECHANISMS; ENGINEERING ELEMENTS AND UNITS; FLEXIBLE SHAFTS; FORGE FURNACES; FORGING; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HAMMERING; HEATING; LIGHTING; MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES,RIVETS, BOLTS OR WHEELS; MECHANICAL ENGINEERING; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; PERFORMING OPERATIONS; PRESSING METAL; PUNCHING METAL; RIVETING; ROTARY BODIES OTHER THAN GEARING ELEMENTS; SHAFTS; THERMAL INSULATION IN GENERAL; TRANSPORTING; WEAPONS

To provide a crank shaft manufacturing method comprising preliminarily molding steps in which volume distribution of a material can be performed more precisely.SOLUTION: A crank shaft manufacturing method comprises first-third preliminarily molding steps. In the first preliminarily molding step, a portion corresponding to a journal and a portion corresponding to a pin of a billet are reduced and molded into s flat shape using a pair of first molds, and a portion corresponding to a web of the billet is reduced using the first molds so that a length of a portion corresponding to an arm is shorter than a length of a portion corresponding to a counter weight in a reducing direction of the first molds. In the second preliminarily molding step, a rough portion corresponding to the journal is reduced using a second mold and the portion corresponding to the pin is decentered using a decentering mold, and a rough portion corresponding to a web is supported by the second mold so that the length of the portion corresponding to the arm is kept to be shorter than the length of the portion corresponding to the counter weight in the reducing direction of the first molds. In the third preliminarily molding step, the rough portion corresponding to the web is reduced to be decreased in thickness using a third mold.SELECTED DRAWING: Figure 4A 【課題】予備成形工程において材料の体積配分をより精密に行うことができるクランク軸の製造方法を提供する。【解決手段】クランク軸の製造方法は、第１～第３予備成形工程を備える。第１予備成形工程では、一対の第１金型を用い、ビレットのジャーナル相当部及びピン相当部を圧下することで扁平状に成形し、ビレットのウェブ相当部を、第１金型の圧下方向においてアームに相当する部位の長さがカウンターウエイトに相当する部位の長さよりも短くなるように、第１金型で圧下する。第２予備成形工程では、第２金型で荒地のジャーナル相当部を圧下し、偏心型でピン相当部を偏心させるとともに、荒地のウェブ相当部を、第１金型の圧下方向におけるアームに相当する部位の長さがカウンターウエイトに相当する部位の長さよりも短い状態に維持されるように第２金型で支持する。第３予備成形工程では、第３金型を用い、荒地のウェブ相当部を圧下して厚みを減少させる。【選択図】図４Ａ