| 摘要 |
PURPOSE:To reduce the number of processes and the number of assembling processes by a method wherein a counter balance weight is formed with a semicircular member and an arcuate member integrally secured to the one end surface of the semicircular member, and the arcuate member is manufactured by a forging work by using a rodform member serving as a starting material. CONSTITUTION:C.B.W (counter balance weight) 70 has a semicircular member 71 and an arcuate member 40. The arcuate member 40 is a thick arcuate integral one- piece, and three columnar protrusion parts 41 are formed on the surface of the semicircular member 71 side. The protrusion parts 41 are inserted in three through-holes formed in the semicircular member 71, and the tip part of each the protrusion part is squeezed to secure the arcuate member 40 to the semicircular member 71. In manufacture of the arcuate member 40, a round rod or square rod, having soft iron property, is first cut to proper lengths to prepare a material. The material is bent by cold forging, and a swaging work is applied thereon to form a raw section 40a. Thereafter, three columnar protrusion parts 41 are formed through forward extrusion processing by cold forging to produce on arcuate member 40. |
