Plastic tube corrugator with mold blocks

A machine cooperable with an extruder to continuously mold plastic, comprising:

• means defining a first continuous path on the machine;
• a plurality of separate mold blocks guided along the first continuous path of said machine;
• means for bringing each of said mold blocks into cooperation with another mold block along a molding section of the first continuous path to form a mold tunnel, whereby said mold blocks enter the molding section at its beginning and exit the molding section at its end;
• a mold train drive driving a selected number of mold blocks at the beginning of the molding section to continuously drive the mold blocks along the molding section at a selected speed;
• a shuttle drive chain driven around a second continuous path which has a first portion substantially following said first continuous path and a second portion spaced from said first path along a substantial portion of said molding section, said shuttle drive chain including first and second connecting section spaced along the shuttle drive chain and removably connected to selected mold blocks when positioned along the second path first portion and disconnected from said selected mold blocks when positioned along the second path second portion;
• and
• means for selectively driving said shuttle drive chain around said second path at the selected speed of the mold train drive when one connecting section is connected to a mold block at the beginning of the molding section, and
• at a speed faster than the selected speed after a connecting section enters the second path second portion.

A machine cooperable with an extruder to continuously mold plastic, comprising:

• means defining a first continuous path on the machine;
• a plurality of separate carriages for carrying mold blocks about the first continuous path of said machine, each of said carriages carrying at least one mold block which cooperates with another mold block along a molding section of the first continuous path to form a mold tunnel in the molding section, said carriages carrying the mold blocks along said path whereby the mold blocks enter the molding section at its beginning adjacent the extruder and exit the molding section at its end;
• means for bringing cooperating mold blocks together along the molding section to form a portion of the mold tunnel;
• a mold train drive engaging a selected number of carriages at the beginning of the molding section to continuously drive carriages along the molding section at a selected speed;
• a shuttle drive chain driven around a second continuous path which has a first portion substantially following said first continuous path and a second portion spaced from said first path along a substantial portion of said molding section, said shuttle drive chain including first and second carriage engaging sections spaced along the shuttle drive chain and adapted to engage a carriage when positioned along said first portion of the second continuous path and adapted to disengage a carriage when positioned along said second portion of the second continuous path;
• and
• means for selectively driving said shuttle drive chain around said second path, said driving means selectively driving said drive chain at the selected speed of the mold train drive when an engaging section engages a carriage at the beginning of the molding section,
• accelerating said drive chain to a speed faster than the mold train drive selected speed when an engaging section enters the second path second portion, and
• decelerating the drive chain from said faster speed to the mold train drive selected speed as an engaging section and engaged carriage approach the beginning of the molding section.