Method and apparatus for cleaning interengaging stretch rollers

Abstract

To clean a pair of counterrotating stretch rollers having surface formations that interengage and that stretch a laminate web transversely to a travel direction in which the web passes between the interengaging rollers gas streams carrying dry-ice particles are directed at surfaces of the counterrotating rollers such that the particles free contaminants from surfaces of the rollers. The freed contaminants and dry-ice particles are aspirated from immediately adjacent each of the rollers while the rollers are rotating and, in fact while the production operation of the web is taking place.

We claim: 
     
         1 . A method of cleaning a pair of counterrotating stretch rollers having surface formations that interengage and that stretch an elastic laminate web transversely to a travel direction in which the web passes between the interengaging rollers, the method comprising the steps of:
 directing a gas stream carrying dry-ice particles at surfaces of the counterrotating rollers such that the particles free contaminants from surfaces of the rollers; and   aspirating freed contaminants and dry-ice particles from immediately adjacent each of the rollers.   
     
     
         2 . The method defined in  claim 1 , wherein each of the webs rotates in a respective rotation direction and each of the rollers has an inner side engaged with the inner side of the other roller and an outer side, gas streams carrying the dry-ice particles impinging the outer sides of the respective rollers, the contaminants and dry-ice particles being aspirated from the outer sides of the rollers downstream in the rotation direction of the respective roller from the respective nozzle. 
     
     
         3 . The method defined in  claim 1 , wherein the gas streams are projected from respective nozzles, the method further comprising the step of:
 reciprocating the nozzles parallel to rotation axes of the rollers back and forth along the counterrotating rollers.   
     
     
         4 . The method defined in  claim 3 , wherein the freed contaminants and dry-ice particles are aspirated through ports extending generally a full axial length of each of the rollers. 
     
     
         5 . The method defined in  claim 1 , wherein the carrier-gas stream is at a temperature below the freezing temperature of carbon-dioxide and gaseous carbon dioxide is added to the carrier-gas stream to form the particles. 
     
     
         6 . The method defined in  claim 1 , wherein the formations of each roller consist of radially outwardly projecting ridges alternating with radially outwardly open grooves, the ridges of each roller engaging in the grooves of the other roller. 
     
     
         7 . In combination with an apparatus having a pair of counterrotating rollers having surface formations that interengage and that stretch a laminate web transversely to a travel direction in which the web passes between the interengaging rollers,
 means for directing a gas stream carrying dry-ice particles at surfaces of the counterrotating rollers such that the particles free contaminants from surfaces of the rollers; and   means juxtaposed with the rollers for aspirating freed contaminants and dry-ice particles.   
     
     
         8 . The apparatus defined in  claim 7 , wherein each of the webs rotates in a respective rotation direction and each of the rollers has an inner side engaged with the inner side of the other roller and an outer side, the means for directing including respective nozzles aimed at the outer sides of the respective rollers, the means for aspirating including respective suction ports juxtaposed with the outer sides of the rollers downstream in the rotation direction of the respective roller from the respective nozzle. 
     
     
         9 . The apparatus defined in  claim 7 , wherein the means for directing includes respective nozzles directed at the rollers. 
     
     
         10 . The apparatus defined in  claim 9 , further comprising actuator means for reciprocating each of the nozzles along the respective roller parallel to a rotation axis of the respective roller. 
     
     
         11 . The apparatus defined in  claim 10 , wherein the means for aspirating means includes respective suction ports open radially inwardly immediately adjacent each of the rollers and extending generally a full axial length of each of the rollers. 
     
     
         12 . The apparatus defined in  claim 7  wherein the means for directing includes a source of the supercold carrier gas and means for mixing gaseous carbon dioxide with the supercold carrier gas to form the dry-ice particles. 
     
     
         13 . The method defined in  claim 7 , wherein the formations of each roller consist of radially outwardly projecting ridges alternating with radially outwardly open grooves, the ridges of each roller engaging in the grooves of the other roller.