Embossing roller and method for the manufacturing thereof
A method for obtaining an incision in an embossing roller using a hob to provide protuberances that are rounded on top and which improve the quality of the embossed material and reduce the wear of the mechanical components of the embossing units. The shape of the protuberances is obtained by machining the cylindrical surface of the roller placed between the tailstocks of the lathe using a hob that has teeth, the profile thereof being complementary to the cross-section of the protuberances. A portion of the hob with the teeth generates the grooves that define the side faces of the protuberances. The grooves between the teeth of the hob have a profile that is curvilinear in a cross-sectional view. With a double pass at two different inclinations of the surface of the roller, the protuberances of FIGS. 5 and 6 are generated.
1. A method for manufacturing an embossing roller comprising providing a roller with an axis and a plurality of protuberances arranged according to a geometrical distribution, each of said protuberances being substantially in a shape of a truncated pyramid with a major base closer to the axis of the roller, a top surface further away from the axis of the roller, and planar side surfaces generated by chip removal using a hob, wherein chip-removal machining of top surfaces of the protuberances is completed by said hob in absence of subsequent grinding, and said hob includes teeth with grooves therebetween wherein at least some of the grooves have a profile that is curvilinear in cross-sectional view so that said hob shapes at least some of said top surfaces with rounded edges radiusing to at least some of the planar side surfaces of said protuberances, wherein said protuberances are provided in helically aligned arrangements around the axis of the roller, and wherein said top surfaces are generated via interaction of the roller with said grooves of said hob, each said top surface being generated by chip removal using said hob.
2. The method according to claim 1 , wherein said protuberances are generated by at least one first pass and one second pass of the hob on a surface of the roller while said roller is kept in rotation, to generate a first series of helical grooves during said first pass and one second series of helical grooves during said second pass, the helical grooves of the first series and said second series intersecting one another to generate said protuberances.
3. The method according to claim 1 , wherein the top surface of each of said protuberances has entirely a convex curved shape.
4. The method according to claim 1 , wherein said protuberances are generated in at least two distinct heights on one roller.
5. A method for manufacturing an embossing roller comprising providing a roller with an axis and a plurality of protuberances arranged according to a geometrical distribution, each of said protuberances being substantially in a shape of a truncated pyramid with a major base closer to the axis of the roller, a top surface further away from the axis of the roller, and planar side surfaces generated by chip removal using a hob, wherein chip-removal machining of top surfaces of the protuberances is completed by said hob in absence of subsequent grinding, and said hob includes teeth with grooves therebetween wherein said grooves have a profile that is curvilinear in cross-sectional view so that said hob shapes said top surfaces so that said top surfaces have rounded edges radiusing to all of the planar side surfaces of a corresponding protuberance of said protuberances, wherein said protuberances are provided in helically aligned arrangements around the axis of the roller.
6. A method for manufacturing an embossing roller comprising providing a roller with an axis and a plurality of protuberances arranged according to a geometrical distribution, each of said protuberances being substantially in a shape of a truncated pyramid with a major base closer to the axis of the roller, a top surface further away from the axis of the roller, and planar side surfaces generated by chip removal using a hob, wherein chip-removal machining of top surfaces of the protuberances is completed by said hob in absence of subsequent grinding, and said hob includes teeth with grooves therebetween wherein the grooves have a profile that is curvilinear in cross-sectional view so that said hob shapes said top surfaces so that said top surfaces have a convex shape radiusing to all of the planar side surfaces of a corresponding protuberance of said protuberances via convex curved portions of surfaces, wherein said protuberances are provided in helically aligned arrangements around the axis of the roller.
7. The method according to claim 6 , wherein said protuberances are shaped with a convex top surface radiused to all the planar side surfaces via convex curved portions of surfaces.