| 摘要 |
PURPOSE:To obtain the sprocket which is light, durable, accurate in dimensions thereof, productive and inexpensive by a method wherein teeth of a gear, made of plastics, is formed integrally around the outer periphery of the main frame of the sprocket made of steel plate or made by die casting. CONSTITUTION:Two sheets of plates 1a for the main frame of the sprocket having boss sections 2a, arms 3a and outer peripheral plates 4a are made by press-forming a mild steel sheet while the main frame 1 of the sprocket is made by a method wherein a boss section reinforcing plate 2b is pinched between these two sheets of plates 1a for the main frame of the sprocket and these three sheets of plates 1a, 2b, 1a are combined and secured by stop-welding 7 at the boss section 2a and the arms 3a. Then, the main frame 1 of the sprocket is set into a plastic mold and the teeth of gear 5 made of plastics is formed around the outer periphery thereof. |
