MXPA06009927A - Milling rollers for vertical miller - Google Patents

Abstract

The invention relates to a composite milling roller, produced by casting, comprising peripheral inserts of a high wear-resistance and high hardness material, sealed in a ductile material on said casting. The roller comprises first zones subject to high wear and second zones subject to low wear, characterised in that said first zone of said roller comprises inserts on the peripheral face thereof with adjoining parts and, in said second zone, a non-adjoining part. The gap between the non.-adjoining parts is filled with said ductile material of the cast matrix permitting an adequate mechanical anchoring of the inserts.

Description

SHREDDING ROLLERS FOR VERTICAL SHREDDER FIELD OF THE INVENTION The purpose of the present invention is to provide improvements to crushing rollers for crushers in general, and for "vertical axis" crushers in particular.

BACKGROUND OF THE INVENTION The "vertical axis" shredders are used, for example, to grind mineral coal or glass brick. They are essentially made of a rotating rail that supports rollers that are driven by the rotational movement of the rail along the vertical axis. The material to be crushed is fed to a central supply channel and falls on the rail, where it is crushed and milled between the rail and the rollers. The ground material is then recovered from the periphery of the rail. Various types of roller shapes are possible, such as conical or toroidal rollers. DE 44 00 797 A1 discloses rollers of this form in which the wearing parts are mechanically sealed by a mechanical fastening means. JP 2001 129418 discloses a mechanical shredder with wear parts provided on the outer surfaces of the rolls, which allow their easy replacement when the slots show signs of wear. These wear parts are inserted into a core in the form of an inverted T so they adhere perfectly to the entire surface of the projections. The techniques used in the German and Japanese documents do not use the casting technology of the projections. The techniques used in the German and Japanese documents do not use the casting technology to empty a more ductile material around inserts that allow to fix the latter in the remaining mass of the roller. Specific forms of vertical axis shredders are shown in figures 1 and 2. This subject is described in more detail in patent EP 0476 496 B1. This patent describes, among other things, a particular configuration of the grinding rolls whose characteristic appearance is that the wear surface is essentially made of peripheral inserts in very hard materials with high wear resistance (such as cast iron with a high level of wear). chrome), mechanically sealed in a matrix of a ductile material. In this version, the inserts are produced in advance with a rib in projection on at least one side longitudinal side and then placed side by side in a mold, leaving between them a space defined by the thickness of their ribs. The roller is produced in the form of a bimetallic part by a casting technique by emptying a more ductile material that ensures the metallic connection of the inserts in the remaining mass of the roller formed by the ductile material. The peripheral inserts are therefore separated by ribs in relation to each other, the ductile material, during the manufacture of the roller by casting, can infiltrate between the inserts to the peripheral wear surface itself, thus ensuring that the inserts are well fixed in these parts. This arrangement leads to a succession of hard inserts that are essentially separated by a space in a more ductile material (the exception being the separation ribs). In order for the ductile material to be continuously infiltrated between the Inserts, the space created between the inserts when they are placed in the mold would progressively increase from the periphery towards the middle part in such a way that the molten metal does not coagulate on contact with the cold inserts , thus avoiding the complete filling of this space with ductile metal. However, due to the wear of the part in use, this arrangement changes, creating in the periphery a ductile space that is increasingly wider, resulting from the slope of the sides of this space. This, however, causes the unfortunate effect of reducing the hard peripheral surface of the inserts and, as a result, of accelerating part wear. Moreover, in the case of crushing rollers, localized preferential wear is observed, generally at the outer edges of the roller. This wear affects the useful life of the rollers but also the quality of the crushed product as well as the crushing performance since the surface of support of the roller on the rail is reduced and this is even greater since the rail itself is subjected to wear during the performance. In the case where, in accordance with a recent technical development, the inserts contain internal reinforcement of ceramic material to reduce wear, the presence of an unprotected space between the inserts means that during operation, a groove is created between the inserts , thus detaching the ceramic reinforcement and splintering its edges. This phenomenon greatly reduces the efficiency of the ceramic reinforcement as it produces very abrasive materials in addition to the fact that its potential wear resistance decreases with its size. In the aforementioned patent, there is also a description (in relation to Figures 5A to 9) of a collar embodiment that compensates the wear profile in accordance with the generatrix. To do this, the inserts do not extend in their longitudinal direction along the entire length of the generatrix, so they leave, on the outer edge of the rollers, a peripheral ear that belongs to the ductile cast iron support, which constitutes the rest of the roller. Very rapid wear is therefore deliberately caused in this area of the roller to compensate for the fact that this area normally wears less quickly. However, this method has the disadvantage that the. Wear on the ear of the ductile cast iron exposes the end of the insert to chipping similar to that described above with respect to the longitudinal edges of the insert, with the same damaging consequences.

OBJECT OF THE INVENTION The purpose of the present invention is to provide a new form of insert to avoid the drawbacks of the most advanced technique solutions.

Characteristic elements of the invention The present invention describes a grinding roll of a mixed material, produced by casting, having peripheral inserts in a material with high wear resistance and high hardness, sealed during casting in a ductile matrix, said ductile matrix infiltrating around the peripheral insert or therein during this casting in such a way that a close contact is formed in the interface between the peripheral inserts and the ductile matrix, said roller having the first areas subject to heavy wear and the second areas subject to light wear where the first zone comprises on its peripheral side inserts with a part supported and the second zone has a part that is not supported, the space in the part that is not supported being filled with the ductile material during casting, allowing sufficient mechanical fixation of the inserts. In a preferred embodiment of the invention, the supported faces that come into contact with their neighboring faces in successive inserts have a contact line corresponding to the radii of the circle formed by the roller. According to the present invention, the ratio of the lengths of the faces supported with respect to the lengths of the areas where the faces do not rest is greater than or equal to 0.2. In general, the invention specifies that the ratio between the lengths of the areas where the faces rest on the lengths of the areas where the faces do not rest is between 0.2 and 20. In a particularly preferred embodiment of the invention, the Wear resistance of the inserts, in particular in the support parts, is increased by a ceramic reinforcement selected from the group of oxides, carbides, nitrides or borides. Also according to the invention, the insert comprises at least one recess that allows its sealing in the matrix casting in the ductile material.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows schematically a "vertical axis" shredder. Figure 2 shows the crushing mechanism acting between the rail and the roller 1 with heavier wear zones 2 and 4 and lighter wear zones 3. The wear that can occur on the rail is also shown. Figure 3 shows schematically in perspective a roller as in the most advanced technique for which a certain number of separate inserts extending longitudinally over the entire length of the generatrix of the roller is shown. Figure 4 shows the insert as in the most advanced technique, showing the separation ribs 20 that were not shown in figure 3. Figures 5A and 5B show an example of wear profiles observed in two types of rollers as in most advanced technique. Figure 6 shows the formation of wear slots 16 in the inserts as in the most advanced technique. Figure 7 shows the flanking of the edges of ceramic reinforcements 17 and 18 of the inserts resulting from the formation of grooves shown in Figure 6. Figure 8 is a view of a set of inserts juxtaposed as in the invention . Figure 9 is a sectional view of an insert in the area 14, as in Figure 8. Figure 10 is a plan view of the partially supported arrangement of three inserts as in the invention. Figure 11 is a sectional view of an insert as in Figure 10. Figures 10 and 11 correspond to Figures 8 and 9 respectively in the case where the inserts comprise ceramic reinforcements (shown in points). Identical reference numbers are used in the various appended figures for identical or essentially similar constituent elements, both for the description of the most advanced technique and for the embodiment as in the invention. In figures 3 and 4 showing modalities as in the most advanced technique, the common reference number 1 indicates a roller having inserts 5 which, as a result of the presence of the ribs 20 during roll forming by casting, are longitudinally spaced apart, the ribs 20 serving as spacers. As indicated above, to allow the passage of the ductile metal 19 designed to globally form the remaining part of the roller 1 between the inserts through the wear surfaces themselves during roll casting, progressive separation between the inserts is provided. an angle a from the periphery to the roller axis (see figure 3). It can be seen in the operation that, as a result of differential wear, the space between the roller and the table in the longitudinal direction is no longer constant, which greatly reduces the grinding efficiency, especially because the table itself can be subject to wear. This is shown in Figure 2. Moreover, the wear on the rollers becomes heavier since the peripheral surface of the insert is reduced by the existence of grooves of increasing width that are created during the operation between the hard inserts. Depending on the shape of the roller, either conical or toroidal, and of the crusher type, a profile 4 can be seen as shown in Figures 5A-5B, varying for example between one or two heavy wear zones 2 and 4 and a zone with slight wear 3. In order to increase the resistance to wear of the inserts 5, in particular on their external parts 14, a reinforcement can be provided there by infiltrating a porous ceramic core: oxides, carbides, nitrides, borides or other substances as described for example in patent EP 0930 948 B1 or by creating a ceramic structure in situ. In the case of the use of a mixed material with a ceramic reinforcement, the formation of grooves of increasing size resulting from wear during the operation would present a major drawback because these grooves give off the ceramic contained in the insert (FIG. 6) that, under the effect of impacts and pressure, splinters on the edges (figure 7). This considerably increases the wear and tear and destroys to an important degree the point of this ceramic reinforcement. Figure 6 shows the formation of grooves 16 in accordance with the first design, with inserts 5 without ceramic reinforcement. Figure 7 shows what happens during the operation when a ceramic reinforcement 18 is incorporated in the inserts 5. It is observed that after the formation of the grooves 16 in the ductile metal, the flanges 17 of the infiltrated ceramic mass 18 breaks , releasing very abrasive materials accelerating the formation of irregular wear profile. Given these experimental data, the inserts are designed as in the invention in such a way as to create a differential wear resistance between the parts subject to heavy wear 2 and 4 and the parts subject to light wear 3. In accordance with the invention, this effect it is obtained by using inserts 5 (see FIG. 8 et seq.) which rest on the aforementioned part subjected to heavy wear 2 and which maintain the spaces 12 in the part subject to lighter wear 3 which are filled by a cast ductile metal 19. Therefore, an area with high wear resistance 14 and an area with a lower wear resistance 13 are obtained. The faces 6 and 7 come into contact with their neighboring faces in the successive inserts (see FIGS. 8 and 10) they are aligned in the center of the roller, that is to say, their line of contact in section corresponds to the radii of the circle formed by the roller. This ensures perfect contact between the inserts 5 when they are placed close to each other, while the depressed surfaces 10 and 11 define the spacing between the inserts, thus creating an area that is less resistant to wear 13 on the inside of the roller , while the most exposed surface 14 will be continuous, without the risk of slots occurring and, as a result, without the risk of a reduction in wear resistance. The relative position of the area (s) subject to heavy wear compared to the position of one of the areas subject to light wear will depend on the type of shredder and the type of roll and, most particularly, on its geometrical shape. The ratio of the width of the zone (s) strongly exposed to wear with respect to the width of the zone (s) slightly exposed to wear is usually greater than or equal to one. . The relationships between the respective widths of these same zones from 1 to 1.5 allow a sufficient crushing area and adequate fixation of the inserts in the matrix. The fact that the internal part 3 of the insert retains the ability to form grooves is beneficial in itself in the sense that it therefore ensures a better roll impulse by reducing the slip or slip effect on the material to be crushed The fixation of the inserts in the matrix is mechanically ensured and is essentially by means of the shape of the lower part 15 of the insert, as shown in Figure 9. This shape is selected so as to allow a strong recess of a type of Dovetail, a hole or other means of fixation. Figures 10 and 11 show the continuity in accordance with the invention of the ceramic reinforcements 18 on the external part 14 of the wear surface of the inserts formed by the two parts 13 and 14, which removes the brittle edges and, as a result , the loss of material designed to resist wear.

Key 1 Crushing roller with inserts 2 and 4 Area subjected to heavy wear 3 Area subject to light wear 5 Peripheral inserts 6 and 7 Support surfaces in the area with high resistance to wear 10 and 11 Depressed or non-bearing surfaces in the area of lower wear resistance 12 Spaces in the part with lower wear resistance 13 Area subject to the lowest wear level 14 External part of the inserts subject to the highest wear level 15 Recess in the lower part of the insert 16 Wear slot in operation 17 Treble rends of the ceramic reinforcement 18 Ceramic reinforcement of the insert 19 Ductile material 20 Spacing ribs

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. - A mixed crushing roller (1), produced by casting, comprising peripheral inserts (5) made of a material with high resistance to wear and high hardness, sealed during casting in a ductile matrix (19), said ductile matrix ( 19) infiltrating around the peripheral insert (5) or therein, during this casting in such a way that to establish close contact at the interface between said peripheral inserts (5) and said ductile matrix (19), said roller (1) comprises first areas subject to heavy wear (14) as well as second areas subject to light wear (13), wherein the first zone (14) has, on its peripheral surface, inserts (5) with a support part (6.7) ) and the second zone (13) has a non-supporting part, the space in the non-supporting part (12) being filled by the ductile material (19) during the casting, allowing sufficient mechanical fixation for the inserts .

2. The roller according to claim 1, further characterized in that the bearing surfaces (6) and (7) that contact their neighboring surfaces in successive inserts have a line of contact corresponding to the radii of the circle formed by the roller (1).

3. The roller according to claim 1 or 2, further characterized in that the ratio of the lengths of the support faces to the lengths of the areas where the faces do not rest is greater than or equal to 0.2.

4. The roller according to claim 3, further characterized in that the ratio between the lengths of the areas where the faces are supported with respect to the lengths of the areas where the faces do not rest is between 0.2 and 20.

5. The roller according to any of claims 1 to 4, further characterized in that the wear resistance of the inserts (5), in particular in the support parts, is increased by a ceramic reinforcement selected from the group of oxides , carbides, nitrides or borides.

6. The roller according to any of the preceding claims, further characterized in that the insert (5) comprises at least one recess (15) allowing its sealing in the die cast in the ductile material (19).