RACK SHAFT STOCK FORGING DEVICE, MANUFACTURING METHOD USING THE FORGING DEVICE, AND RACK SHAFT STOCK

• Main Authors: NARISAWA MASAMI, INAGAKI RYOTA, FUKUI MASATO
• Format: Patent
• Language: English; Japanese
• Published: 20.06.2016
• Subjects: BLASTING; ENGINEERING ELEMENTS AND UNITS; FORGE FURNACES; FORGING; GEARING; 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; THERMAL INSULATION IN GENERAL; TRANSPORTING; WEAPONS

PROBLEM TO BE SOLVED: To provide a rack shaft stock forging device capable of forming rack teeth of high shape accuracy even when the rack teeth are formed by forging, a manufacturing method using the forging device, and a rack shaft stock.SOLUTION: The forging device 20 is a forging device for a rack shaft stock 11 having first die 21a and a second die 21b constituting a half-sealed forging die. The rack shaft stock 11 includes a rack tooth forming part 13 and burrs 15. The first die has a first groove part 21a2 and a first edge surface 21a1. The second die is provided to face the first die, and includes a second groove part 21b2 and a second edge surface 21b1. The burrs 15 are bulged between the first edge surface 21a1 and the second edge surface 21b1 to be formed by the forging of a raw material before the formation of rack teeth 16 by using the first die and the second die. A space distance between the first edge surface 21a1 and the second edge surface 21b1 during the formation of the burrs 15 is smaller at the first end 13a of the rack tooth forming part 13 than at the center of the rack tooth forming part 13.SELECTED DRAWING: Figure 2 【課題】鍛造によってラック歯を形成しても、高い形状精度を備えるラック歯の形成が可能なラック軸素材の鍛造装置、その鍛造装置を用いた製造方法及びラック軸素材を提供する。【解決手段】鍛造装置２０は、半密閉鍛造型を構成する第一型２１ａ及び第二型２１ｂを備えるラック軸素材１１の鍛造装置である。ラック軸素材１１は、ラック歯形成部１３と、バリ１５と、を備える。第一型は、第一溝部２１ａ２、及び第一縁面２１ａ１を備える。第二型は、第一型に対向して設けられ、第二溝部２１ｂ２、及び第二縁面２１ｂ１を備える。バリ１５は、第一型、及び第二型を用いてラック歯１６の形成前の原材料の鍛造により、第一縁面２１ａ１と第二縁面２１ｂ１との間に張り出されて形成される。そして、バリ１５の形成時における第一縁面２１ａ１と第二縁面２１ｂ１との離間距離は、ラック歯形成部１３の中央部よりラック歯形成部１３の第一端部１３ａの方が小さい。【選択図】図２