Tube making machine with diameter control and method

Abstract

A spiral pipe forming system and method which include automatic diameter or dimension sensing and correction.

1 . Apparatus for forming a spiral pipe, comprising lead, mandrel and buttress rolls for forming a spirally wound sheet, the apparatus further including inner and outer pressure rolls engaging and crimping together adjacent edges of the spirally wound sheet; a sensing system for monitoring changes in the diameter of the spirally wound sheet as it is formed and responsively generating signals containing information regarding changes in diameter; and a system responsive to the signals, for moving the buttress rolls toward or away from the mandrel rolls and the pressure rolls to thereby correct the changes in diameter. 
   
   
       2 . Apparatus for forming a spiral pipe, comprising lead, mandrel and buttress rolls for forming a spirally wound sheet, the apparatus further including inner and outer pressure rolls engaging and crimping together adjacent edges of the spirally wound sheet; a sensing system for monitoring changes in the diameter of the spirally wound sheet as it is formed and responsively generating signals containing information regarding changes in diameter; a system responsive to the signals indicating relatively small changes in pipe diameter, for moving the inner and outer pressure rolls in unison radially inward or outward relative to the axis of the pipe, to correct the relatively small changes in diameter; and a system responsive to the signals indicating relatively large changes in pipe diameter, for moving the buttress rolls toward or away from the mandrel rolls and the pressure rolls, to correct the relatively large changes in diameter. 
   
   
       3 . A method of forming a spiral pipe with diameter control, comprising: using lead, mandrel and buttress rolls, forming a spirally wound sheet having adjacent edges; using interior and exterior pressure rolls, crimping adjacent edges of the sheet together; monitoring the diameter of the spirally wound sheet for changes therein; responsive to changes in the diameter, generating signals containing information regarding the changes in diameter; and automatically applying diameter correction selected from (1) moving the inner and outer pressure rolls in unison radially inward or outward relative to the axis of the spirally wound sheet, to move the adjacent edges of the spirally wound sheet together, to thereby correct relatively small changes in diameter; and (2) moving the buttress rolls toward or away from the mandrel rolls and the pressure rolls, to thereby correct relatively large changes in diameter.