Rotatable Drum for Laundry Washing Machines and Assembly Method of the Rotatable Drum

Abstract

A rotatable drum ( 1 ) for laundry washing machines ( 2 ) comprises a substantially cylindrical lateral wall ( 13 a ) provided with a plurality of through holes ( 15 ). The cylindrical lateral wall ( 13 a ) is also provided with a one or more, outwards-projecting, first bulges ( 16 ) with at least one of the through holes ( 15 ) located therein.

1 . A rotatable drum for laundry washing machines comprising a substantially cylindrical lateral wall provided with a plurality of through holes, said cylindrical lateral wall being provided with one or more, outwards-projecting, first bulges with at least one of said through holes located therein. 
     
     
         2 . A rotatable drum as claimed in  claim 1 , wherein each first bulge has at least a first through hole located at least roughly at its center, and/or a number of second through holes which are located at the vertexes of a polygon locally at least roughly centered to the first bulge. 
     
     
         3 . A rotatable drum as claimed in  claim 1 , wherein each first bulge has six second through holes which are located at the vertexes of a hexagon locally at least roughly centered to the first bulge. 
     
     
         4 . A rotatable drum as claimed in  claim 1 , wherein said first bulges comprise a lateral wall and a bottom, (the one or more through holes located in each first bulge being placed in its bottom. 
     
     
         5 . A rotatable drum as claimed in  claim 1 , wherein said first bulges are realized on the cylindrical lateral wall so as to be aligned with one another along a number of adjacent longitudinal rows staggered with respect to one another. 
     
     
         6 . A rotatable drum as claimed in  claim 1 , wherein the perimeter of said first bulges is substantially circular in shape. 
     
     
         7 . A rotatable drum as claimed in  claim 1 , wherein said cylindrical lateral wall is also provided with a number of outwards-projecting second bulges each of which is at least roughly centered to a respective through hole. 
     
     
         8 . A rotatable drum as claimed in  claim 7 , wherein each second bulge is shaped so as to form a respective outwards-projecting funnel which is substantially truncated cone shaped. 
     
     
         9 . An assembly method of a rotatable drum of a laundry washing machine wherein the rotatable drum comprises a substantially cylindrical lateral wall provided with a plurality of through holes; the assembly method comprising the steps of:
 punching a metal- sheet so as to realize, on the latter, a number of through holes spaced from one another;   pressing the metal-sheet-around one or more of said through holes, so as to realize, on said metal-sheet, a number of first bulges, each of which comprises one or more of said through holes locally spaced apart from the natural reference laying plane (N) of the metal-sheet;   cylindrically bending said metal-sheet so as to form a cylindrical coil in which said first bulges radially protrude outwards; an   connecting the two opposite lateral edges of said metal-sheet, so as to form a cylindrical sleeve.   
     
     
         10 . An assembly method as claimed in  claim 9 , further comprising the step of pressing the metal-sheet so as to realize, around each through hole, a respective outwards-projecting second bulge which is substantially centered to the corresponding through hole. 
     
     
         11 . An assembly method as claimed in  claim 10 , wherein each second bulge is shaped so as to form, on the metal-sheet, an outwards-projecting funnel, which is substantially truncated cone shaped. 
     
     
         12 . An assembly method as claimed in  claim 9 , wherein the metal-sheet is pressed so that each first bulge has at least a first through hole located at least roughly on its centre. 
     
     
         13 . An assembly method as claimed in  claim 9 , wherein the metal-sheet is punched so as to form, on the latter, several groups of through holes each of which comprises a number of through holes located at the vertexes of a polygon; and afterwards the metal sheet is pressed so as to realize a number of first bulges each of which comprises a number of through holes located at the vertexes of a polygon locally roughly centered to said first bulge. 
     
     
         14 . An assembly method as claimed in  claim 9 , wherein the metal-sheet is pressed so to realize a number of the first bulges aligned along a number of adjacent longitudinal rows, which are staggered with respect to one another. 
     
     
         15 . An assembly method as claimed in  claim 9 , wherein the metal-sheet is pressed so that each first bulge comprises a lateral wall and a bottom, the one or more through holes located in each first bulge being placed in its bottom. 
     
     
         16 . A rotatable drum as claimed in  claim 2 , wherein said first bulges comprise a lateral wall and a bottom, the one or more through holes located in each first bulge being placed in its bottom. 
     
     
         17 . A rotatable drum as claimed in  claim 4 , wherein said first bulges are realized on the cylindrical lateral wall so as to be aligned with one another along a number of adjacent longitudinal rows staggered with respect to one another. 
     
     
         18 . A rotatable drum as claimed in  claim 3 , wherein the perimeter of said first bulges is substantially circular in shape. 
     
     
         19 . An assembly method as claimed in  claim 10 , wherein the metal-sheet is pressed so that each first bulge has at least a first through hole located at least roughly on its centre. 
     
     
         20 . An assembly method as claimed in  claim 10 , wherein the metal-sheet is pressed so that each first bulge comprises a lateral wall and a bottom, the one or more through holes located in each first bulge being placed in its bottom.