Process for producing a casing for a roller press

Abstract

A process for producing a casing for a roller press for subjecting particulate matter to be ground to high pressure treatment, the casing having a profiling defined by profile comb, wherein the process includes the steps of casting a cylindrical hollow body and introducing axial longitudinal grooves onto the surface of the cylindrical hollow body. The material for casting is of a particular composition, where that composition includes, among other components, between 0.0012% and 0.0027%, by weight, of phosphorus (P).

Claims

1. A process for producing a casing for a roller press for subjecting particulate matter to be ground to high pressure treatment, the casing having a profiling defined by profile comb, wherein the process comprises the steps of: casting a cylindrical hollow body, introducing axial longitudinal grooves onto the surface of the cylindrical hollow body, wherein the material for casting has the following composition: TABLE-US-00004 Element Min. % by weight Max. % by Weight C 2.7% 2.85% Si 0.95% 1.02% Mn 0.55% 0.64% P 0.0012% 0.0027% S 0.022% 0.027% Cr 16.90% 17.50% Mo 0.40% 1.30% Ni 4.35% 4.55%

2. The process according to claim 1, wherein the casting step is performed by static casting.

3. The process as claimed in claim 2, wherein: said step of introducing axial longitudinal grooves into the surface of the cylindrical hollow body is performed by at least one of grinding, machining, and molding in during the casting in a casting mold.

4. The process according to claim 1, wherein the casting step is performed by centrifugal casting.

5. The process as claimed in claim 4, wherein: said step of introducing axial longitudinal grooves into the surface of the cylindrical hollow body is performed by at least one of grinding, machining, and molding in during the casting in a casting mold.

6. A process for producing a profiled casing as claimed in claim 1, further comprising the step of: producing the cylindrical hollow body in a composite casting process, wherein an inner part of the cylindrical hollow body has a different material composition than the outer part of the cylindrical hollow body, and wherein the composition of the inner cylindrical hollow body is selected as follows: TABLE-US-00005 Element Min. % by weight Max. % by Weight C 2.8% 3.6% Si 1.6% 2.60% Mn 0.15% 0.45% P 0.012% 0.060% S 0.011% 0.056% Cr Mo Ni

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail with reference to the figures which follow.

(2) In the figures:

(3) FIG. 1 shows a profiled casing,

(4) FIG. 2 shows a section of the surface of a casing built up by build-up welding,

(5) FIG. 3 shows a profiled casing with a different composition of individual parts of the casing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) FIG. 1 shows a casing 10 according to the invention for a roller press, which has a main casing body 11 and an outer profiling with profile combs 12. According to the invention, it is proposed to select the material of the casing 10 with the aforementioned alloy 15 constituents and to equip the casing 10 with the profile combs 12, where the profile combs 12 have already been molded into the casing 10 during the casting or are shaped subsequently by introducing profile grooves 13 extending in the axial direction (FIG. 2).

(7) The ductility of the main casing body 11 is such that the casing tolerates shrinkage onto a main roller body (not shown here) and also tolerates mechanical loading, which, for example, arises as a result of the passage of a body which cannot be comminuted in the roller nip, such as a relatively large piece of hard metal.

(8) To produce the casing, use is made of a simple process in which firstly a cylindrical hollow body is produced by static casting or centrifugal casting, and then axial longitudinal grooves are introduced onto the surface of the cylindrical hollow body. For the selection of the alloy of the surface of the cylindrical hollow body, it is important for said alloy to have the following composition:

(9) TABLE-US-00002 Element Min. % by weight Max. % by weight C 2.70% 2.85% Si 0.95% 1.02% Mn 0.55% 0.64% P 0.0012% 0.0027% S 0.022% 0.027% Cr 16.90% 17.50% Mo 0.40% 1.3% Ni 4.35% 4.55%

(10) In an embodiment of the invention, the cylindrical hollow body has an inner cylindrical component part and an outer cylindrical component part. The outer cylindrical component part is represented as described above. The inner cylindrical component part, by contrast, has a different composition than the outer cylindrical component part, a composition which is without chromium, molybdenum and nickel, as represented below:

(11) TABLE-US-00003 Element Min. % by weight Max. % by weight C 2.80% 3.60% Si 1.60% 2.60% Mn 0.156% 0.45% P 0.012% 0.060% S 0.011% 0.056% Cr Mo Ni

(12) In this case, the cylindrical hollow body is produced by composite casting.

(13) The axial longitudinal grooves are either already introduced by molding in during the casting or are introduced into the surface of the cylindrical hollow body by grinding or by machining after the cylindrical hollow body has cooled.

(14) FIG. 2 shows that profile combs 12 sit on the worn profile combs 12. These profile combs 12 are build-up welds which are subsequently applied to the profile combs 12 by build-up welding for repairing and for rebuilding a worn casing 10. The selection of the material makes it possible to repair the casing weighing many tons by build-up welding using simple means.

(15) FIG. 3 finally shows a casing having different material compositions for the inner component part 11 of the casing and the outer part 11 of the casing. The inner part 11 of the casing has the aforementioned composition without chromium, nickel and molybdenum, whereas the outer component part of the casing has the aforementioned composition containing chromium, nickel and molybdenum.

(16) In an embodiment of the invention, it is proposed that the inner component part of the casing amounts to 50% of the weight of the casing, preferably 80%, particularly preferably amounts to more than 90% of the weight of the casing. The casings with the small weight proportion of the chromium-containing alloy are distinguished by a high hardness, which is insensitive to build-up welds on the profile combs, the profile combs serving as a foundation for a build-up weld, and by the ductility of the substantially chromium-free material of the inner component part of the casing.

(17) As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

LIST OF REFERENCE SIGNS

(18) 10 Casing 11 Main casing body 5 11 Inner part 11, Outer part 12 Profile comb 12 Build-up weld 13 Profile groove