Ply-band building apparatus

Claim 1

A ply-band building apparatus, which comprises: a fixed frame structure; a rotary shaft journaled on said fixed frame structure and having a bore axially extending therethrough; a ply-band building drum including a plurality of arcuate segments collectively defining the drum surface thereof, each arcuate segment having a central projection at the radially inner wall thereof, a pair of guide flange members fastened on the periphery of said rotary shaft in face-to-face relation with each other, a conical hollow slide member interposed between said guide flange members to be slidably mounted through the hollow thereof on said rotary shaft with the peripheral surface of said conical hollow slide member slidably coupled with the radially inner wall of said central projection of each arcuate segment inclined from the periphery of said each arcuate segment through the same inclination as the peripheral surface of the conical hollow slide member in the axial direction of the building drum, and a pair of side projections radially inwardly extending and respectively radially slidably mounted on said guide flange members, so that said arcuate segments radially simultaneously move in accordance with axial movement of said conical hollow slide member; drum control means including a control rod slidably inserted into said bore of the rotary shaft and connected at one end thereof to said conical hollow slide member, a fluid pressure operated main cylinder assembly having a cylinder bottomed at the both ends thereof and provided at each bottom thereof with a port and a central aperture, a piston slidably accommodated in said cylinder and a piston rod slidably inserted into the central apertures and connected to said piston, one end of said piston rod being connected to said control rod, and a fluid pressure operated subsidiary cylinder assembly having a cylinder bottomed at the both ends thereof and provided at one bottom thereof with a central aperture and a port and at the other bottom thereof with a port, a piston slidably accommodated in said cylinder and a piston rod connected to said piston and slidably coupled with said aperture, said main and subsidiary cylinder assemblies being so mounted on said frame structure that the other end of said piston rod of said main cylinder assembly and said piston rod of said subsidiary cylinder assembly abut on each other when said piston of the main cylinder assembly be in an intermediate position and said piston of the subsidiary cylinder assembly be in an utmost position nearer to said main cylinder assembly.