Roller for high pressure roller grinder, roller grinder, and method for assembling a roller for a roller grinder

1. A roller for a roller grinder, said roller comprising a shaft and a cylindrical grinding shell having an inner face to be retained around the shaft,

wherein the shaft comprises two shaft parts, wherein said shaft parts comprise coupling portions arranged to couple the shaft parts to each other, thereby forming the shaft, wherein

each shaft part has a respective inner end portion, wherein said inner end portions are arranged to be positioned facing each other and to be coupled to each other by said coupling portions

wherein each shaft part comprises a respective hub element against which an inner surface of the grinding shell is to be seated, and

wherein each hub element has a frusto-conical shape and wherein the inner surface of the grinding shell has two inner surface portions, each inner surface portion having a frusto-conical shape corresponding to a frusto-conical shape of the respective hub elements, the inner surface portions of the grinding shell being arranged with a smaller base of the respective frusto-conical shape facing each other and a larger base of the respective frusto-conical shape facing away from each other.

2. The roller as claimed in claim 1 , wherein said grinding shell is in the form of a tubular sleeve.

3. The roller of claim 1 , wherein the coupling portions are arranged to axially force the shaft parts towards each other.

4. The roller of claim 1 , wherein the larger base of the respective frusto-conical shape of the inner surface portions of the grinding shell is arranged at a respective axially outer end of the grinding shell.

5. The roller of claim 4 , wherein the smaller base of the respective frusto-conical shape of the inner surface portions of the grinding shell coincide.

6. The roller of claim 5 , wherein the coupling portions are arranged to axially force the hub elements towards each other, thereby pressing the hub elements against the inner surface of the grinding shell and retaining the grinding shell on the shaft.

7. The roller of claim 1 , wherein the coupling portions of at least one of the shaft parts comprises mechanical, pneumatic, hydraulic or magnetic coupling means.

8. The roller of claim 1 , wherein the coupling portions of at least one of the shaft parts comprises a gripping device longitudinally disposed through the respective shaft part, having an actuation end portion, external to the shaft, and an engaging end portion, projecting from the respective inner end portion and to be engaged in the other respective shaft part.

9. The roller of claim 1 , further comprising an extracting device arranged to force the shaft parts axially away from each other for disassembling the shaft.

10. The roller of claim 9 , wherein the extracting device comprises a chamber, defined between the inner end portions of said shaft parts and a duct disposed through at least one of the shaft parts and having an end open to the chamber and another end open to the exterior of the respective shaft part arranged to be connected to a pressure source, so as to allow the selective pressurization of the chamber to force the shaft parts away from each other in opposite axial directions.

11. The roller of claim 9 , wherein the extracting device comprises a jack arrangement arranged to force the shaft parts away from each other in opposite axial directions.

12. The roller of claim 1 , wherein one of the inner end portions of the shaft parts comprises a guide portion, the other hub element comprising a guide receiving portion in which the guide portion is arranged to be coupled, when the shaft parts are coupled to each other, thereby keeping the two shaft parts axially aligned with one another.

13. The roller of claim 12 , wherein the guide portion comprises at least one end axial projection of the respective inner end portion, the guide receiving portion comprising an end axial recess provided in the other inner end portion and which is dimensioned to slidably receive and axially guide the respective end axial projection, when said shaft parts are coupled to each other.

14. A roller grinder for grinding materials such as minerals, comprising at least one roller including a shaft and a cylindrical grinding shell having an interface surface to be retained around the shaft, wherein the shaft comprises two shaft parts each including a coupling portion arranged to couple the shaft parts to each other to form the shaft, wherein each shaft part has a respective inner end portion, wherein the inner end portions are arranged to be positioned facing each other and to be coupled to each other by the coupling portions,

wherein each shaft part comprises a respective hub element against which an inner surface of the grinding shell is to be seated, and wherein each hub element has frusto-conical shape and wherein the inner surface of the grinding shell has two inner surface portions, each inner surface portion having a frusto-conical shape corresponding to a frusto-conical shape of the respective hub elements, the inner surface portions of the grinding shell being arranged with a smaller base of the respective frusto-conical shape facing each other and a larger base of the respective frusto-conical shape facing away from each other.

15. A roller for a roller grinder, the roller comprising:

a shaft including two shaft parts, wherein the shaft parts comprise coupling portions arranged to couple the shaft parts to each other to form the shaft, wherein each shaft part has a respective inner end portion, wherein the inner end portions are arranged to be positioned facing each other and to be coupled to each other by the coupling portions;

a cylindrical grinding shell having an inner surface to be retained around the shaft; and

an extracting device arranged to force the shaft parts axially away from each other for disassembling the shaft, wherein the extracting device includes a chamber formed between the inner end portions of the shaft parts and a duct disposed through at least one of the shaft parts and having a first end open to the chamber and a second end open to the exterior of the respective shaft part, the second end arranged to be connected to a pressure source to allow the selective pressurization of the chamber to force the shaft parts away from each other in opposite axial directions.