Method of manufacturing two-layer roll and method of manufacturing cylindrical member

1. A method of manufacturing a two-layer roll having a foamed elastic layer provided on a core, and an elastic layer provided on the foamed elastic layer, the method comprising the steps of:

forming the elastic layer, which has a length of 200 mm to 400 mm and outside diameter of 16 mm or less, by use of a cylindrical mold holding a first cylindrical member used to form an outer cylindrical surface of the elastic layer, the first cylindrical member being manufactured by means of machining a solid member, and the first cylindrical member having an inside-diameter error of ±0.02 mm or less and an axial straightness deviation of 0.02 mm or less;

forming a solid primary layer, which has a length of 200 mm to 400 mm and is to be foamed into the foamed elastic layer, on the core by means of side extrusion;

setting the formed elastic layer and the core having the solid primary layer formed thereon in a second cylindrical member of a foaming mold, the second cylindrical member having an inside-diameter error and an axial straightness deviation substantially equal to those of the first cylindrical member; and

foaming the solid primary layer into the foamed elastic layer within the foaming mold including the elastic layer and the core to form the two-layer roll having the foamed elastic layer and the elastic layer, the foamed elastic layer and the elastic layer having a length of 200 mm to 400 mm.

2. A method of manufacturing a two-layer roll according claim 1 , wherein the first and second cylindrical members have an inside-diameter error of ±0.01 mm or less.

3. A method of manufacturing a two-layer roll according to claim 1 , wherein a method of manufacturing each of the first and second cylindrical members comprises the steps of:

drilling a primary bore in the solid member, which serves as a cylindrical-member workpiece;

performing external cylindrical turning on the cylindrical-member workpiece while using the center of the primary bore as a reference;

finishing at least one end face of the cylindrical-member workpiece into a reference face; and

honing an internal cylindrical surface of the primary bore while using the reference face as a reference, thereby obtaining a finished bore.

4. A method of manufacturing a two-layer roll according to claim 3 , wherein the method of manufacturing each of the first and second cylindrical members further comprises the step of quenching the cylindrical-member workpiece, before the step of finishing an end face of the cylindrical-member workpiece into a reference face.

5. A method of manufacturing a two-layer roll according to claim 4 , wherein a parting agent is not used for formation of the elastic layer.

6. A method of manufacturing a two-layer roll according to claim 3 , wherein in the step of finishing an end face of the cylindrical-member workpiece into a reference face, opposite end faces of the cylindrical-member workpiece are finished into corresponding reference faces.

7. A method of manufacturing a two-layer roll according to claim 3 , wherein the method of manufacturing the second cylindrical member further comprises the step of, after the step of forming the finished bore, performing external cylindrical finishing on the cylindrical-member workpiece while using the center of the finished bore as a reference.

8. A method of manufacturing a two-layer roll according to claim 1 , wherein an external cylindrical surface of the elastic layer does not undergo polishing and is treated by use of a surface treatment liquid that contains isocyanate, thereby forming a surface treatment layer.

9. A method of manufacturing a two-layer roll according to claim 8 , wherein the surface treatment liquid further contains at least either a conductivity imparting agent or at least one polymer selected from acrylic fluorine-containing polymers and acryl-silicone polymers.

10. A method of manufacturing a two-layer roll according to claim 8 , wherein the surface treatment is performed before or after the step of foaming.

11. A method of manufacturing a two-layer roll according to claim 1 , wherein an adhesive agent is not provided between the foamed elastic layer and the elastic layer.

12. A method of manufacturing a two-layer roll according to claim 1 , wherein the elastic layer has a thickness of 0.3 mm to 1.2 mm.