EP3256257B1 - Grinding roller and methods for pulling off a strap and shrinking a strap onto the shaft of the grinding roller - Google Patents

Description

The invention relates to a grinding roller of a high-pressure roller press, comprising a shaft, wherein the shaft is rotationally symmetrical with respect. A rotation axis, and at least one wear-resistant bandage, wherein the shaft and the at least one bandage are coaxial and wherein the bandage in a longitudinal section of the shaft non-positively the wave has shrunk. The invention further relates to a method for separating a bandage and a shaft in such a grinding roller and a method for frictionally connecting a bandage and a shaft to such a grinding roller, wherein the bandage and the shaft are designed with respect to their diameter in interference fit.

Grinding rollers are used as part of high-pressure roller presses (roller presses, high-bed roller mills) for the comminution of granular regrind, for example. Of cement clinker used. In this case, a roller gap is formed between two grinding rollers, in which grinding material is drawn in by the two counter-rotating rollers and in which the material to be ground is crushed under high pressure. This results in a high mechanical stress and the grinding rollers. Above all, scratches and micro-machining by the brittle regrind can lead to abrasive wear of the surface and outer layers of the roller. In order to avoid costly repairs and shortened downtime of the high-pressure roll press, measures are taken to protect against wear. In a common form of wear protection, the grinding roller is viewed from the inside to the outside from a shaft that is in the high pressure roller press is stored accordingly, and a coaxial bandage constructed (szB the DE 20 2011 110 190 U1 ). The bandage is made of wear-resistant material, especially made of suitable steel, protects the shaft against abrasion in the area of special grinding stress and often promotes the grinding process by means of a profiled surface. After a certain period of operation occurs in the bandage wear on, but does not need the shaft or the entire grinding roller to be replaced. Rather, it is sufficient an exchange or a workup of the bandage. For this - as well as other maintenance occasions in which bandage and shaft are to be separated from each other - it proves to be advantageous if the frictional connection between shaft and bandage was made by shrinking the bandage, ie by heating and corresponding expansion of the outer part (Bandage) , Mounting on the inner part (shaft) and pressing on the inner part by contraction on cooling. In a reverse manner, a removal of the bandage can then be made, ie by intensive heating of the bandage from the outside until their thermal expansion allows a withdrawal in the axial direction of the shaft.

Such thermally permissible withdrawal of the shaft and the process of shrinking also lead to a heating process for the shaft. In particular, the process of disassembly (but also the assembly) can be significantly promoted by the fact that the shaft is cooled thereby. In this way, the shaft does not expand to the same extent as the heated bandage, so that it comes to a more incoming solution of the compound than without cooling the shaft. In practice, the shafts are provided with a central, i. provided along the axis of rotation arranged cooling hole. By means of this channel-like cooling hole cooling of the shaft in the processes of shrinking or pulling the bandage from the inside is made possible in a simple manner by a flowing through cooling medium.

However, especially in the field of cement production used high-pressure roller presses are characterized by particularly large dimensions. For example, mill roll diameters of up to 3 m are typical, with a thickness of the bandage of about half a meter being not uncommon. As has been shown, for grinding rolls of this size, the system of central cooling for the removal (and mounting) of bandages only poorly or not at all suitable. Due to the distance to the mating surface between the shaft and the bandage, the cooling process does not effectively contribute to the production of a high temperature difference of the outer portions of the shaft and the heated bandage. As a result, in general, the external heat on the bandage must be increased in order to promote a solution of the connection; However, the temperature range raised in this way is not gentle on the material, since structural changes or phase transformations can occur in alloys such as steel even at a few hundred degrees Celsius over time, which reduces the resistance of the grinding roller to the forces acting on it during the grinding process. This is exacerbated by the fact that, with central cooling, the process of releasing (as well as producing) the frictional connection slows down as the size of the rolls increases. This not only means longer and more energy-intensive operations, but also a longer period in which the mentioned phase transformations can occur and take place. A temperature-related significantly stronger cooling in the central area would not only be economically intensive, but would also lead to large temperature gradients in the radial direction within the shaft itself, which also, for example, by tensions, contribute to material weakening.

Coolings that are based on cooling channels in the bandage or in the area between the bandage and shaft or roller body, such as in the DE 1 029 723 A proposed for use in briquetting presses, would not be helpful in the described process of stripping the bandage, since it depends on a high temperature difference between the cool shaft and hot band just in the mating surface. Also the system of radial cooling channels, which, as in DE 25 36 688 A1 proposed for a hot briquetting, by one or leading to several cooling channels in the center of the roller core to the shell or the surface of the core is not transferable to the present problem, since the local coat is not executable because of its segmentation and its paraxial cooling holes as a shrinkable bandage.

Also the other hand in the document WO 2014/012770 improved, complex cooling system for a press roll with bandage is not suitable for use in the processes of thermal removal or shrinkage of a bandage because of its arranged in the drum cooling holes and its core arranged in the roll radial inlet and outlet channels from the center to the bandage. Another pamphlet DE19833456 discloses a method of manufacturing press rolls or ring bandages for press rolls having at least one cooling channel for dissipating heat. Furthermore, this document relates to a press roll produced by this method. The object of the invention is therefore to provide a grinding roller of a high-pressure roller press, in which a simple, fast and gentle material separation of a shrunk bandage of the shaft and a simple, fast and material-friendly frictional connection of a bandage with the shaft are possible even with large shaft diameter. The object of the invention is also to specify a method associated with this grinding roller for separating bandage and shaft and a method for non-positive connection of bandage and shaft.

The object of the invention is achieved by a grinding roller of a high-pressure press with the features of claim 1, by a method for separating a bandage and a shaft in such a grinding roller with the features of claim 6 and by a method for frictional connection of a bandage and a shaft solved such a grinding roller with the features of claim 7. Further advantageous embodiments are specified in the subclaims to claim 1.

According to the invention, it is thus provided that the shaft has cooling bores extending in the axial direction for the flow of coolant. In this case, the channel-like cooling bores, which are completely traversing the shaft and open at both ends for inlet and outlet of the gaseous or liquid coolant, are according to the invention not in or near the center of the shaft, but arranged in the outer region of the shaft, so close to the joint surface between the shaft and shrunk bandage. The shaft of the grinding roller is suitably mounted at high pressure roller presses at the ends, so that the shaft is only in a central region or longitudinal section of the bandage and is protected by this during the milling process against wear. The cooling bores are arranged in the outer region of the shaft in such a way that they pierce the interior of a geometric circular ring through the shaft at a cross section through the shaft perpendicular to the axis of rotation, in the region of the longitudinal section of the shaft with bandage casing. The center of this imaginary circle lies on the axis of rotation. The outer radius r _{max of} the annulus is equal to the outer radius of the shaft r _w , and the inner radius r _{min of} the annulus is one third of the outer radius (1/3 r _max ), preferably two thirds of the outer radius (2/3 r _max ). It has been found that for the inventive methods of thermal disassembly and assembly of the bandages cooling is best suited if it takes place by means of cooling channels within such a metered, outer region of the shaft. The cross-sections through the cooling holes lie entirely within this range, ie in particular not open on the surface (or outer joint surface) of the shaft. Such a construction enables effective cooling of the grinding roller, in particular the shaft, even in the outer region of the shaft, when the shaft diameter is a few meters (typically up to 2.5 m). When exposed to heat from the outside so that the basis of a simple and thereby much faster cooling is given as in the known cooling mode with cooling by a central bore in the shaft. Insofar as cooling is thus possible even at very high temperatures (when mounting or demounting the bandage) already in the area of the joining surface to the bandage, this cooling process runs faster, more effectively and frequently in the shaft with radially shallower temperature gradients (during simultaneous heat action). so that unwanted structural and Phase transformations in the materials used the grinding roller (shaft, bandage), ie in particular steel, are less likely.

For reasons of wear protection, the bandage can be profiled on its surface, so that an autogenous wear protection layer is formed on the grinding roller during the grinding process by adhesion of a layer of comminuted and compacted millbase. However, if further hard wear on the bandage is in turn applied (for example, pin-like or plate-shaped) hard bodies of highly wear-resistant material, these additional bodies are not considered terminologically in the present context as part of the bandage. In particular, their assembly or disassembly are generally separate and possibly separate from the processes described herein of stripping and mounting the bandage on the shaft.

According to the invention, the cooling holes are located in the outer region of the shaft. Due to the sometimes heavy loads of the grinding roller in the grinding operations a symmetrical to the axis of rotation of the roller distribution of the cooling holes is preferable because of the forces acting. An embodiment of the invention therefore provides that the cooling bores in a perpendicular to the axis of rotation executed cross section through the shaft symmetrically distributed on a circle (arrangement circle) with center on the axis of rotation and radius r ₁ , between the outer and inner radius of the pierced, geometric Circular ring is (r _min <r ₁ <r _max ), are arranged. The cooling holes are therefore arranged at equidistant intervals on a circle in the outer region of the shaft, wherein the array of the shaft surface is at least as far engaged in the shaft interior, that the cooling holes are not cut on the shaft surface, ie are open. The symmetrical arrangement also allows for uniform cooling of the shaft in the process of applying and removing the heated bandage.

For material and dimensional reasons, a particularly strong cooling of the shaft when removing and possibly also pulling the bandage on the shaft required be. In order not to reduce the stability of the shaft when force is applied, a plurality of smaller-diameter cooling bores are more suitable here than a few bores of larger diameter. In case of heavy cooling need this can lead to a comparatively large number of cooling holes. For static reasons, it is not recommended here to arrange all cooling holes in a tight sequence on only one arrangement circle. In an alternative embodiment of the invention it is therefore provided that the cooling holes in a perpendicular to the axis of rotation executed cross section through the shaft symmetrically distributed on at least two concentric circles (arrangement circles) with center on the axis of rotation and radii (r ₁ , r ₂ , ... ), which lie between the outer and inner radius of the pierced, geometric circular ring (r _min <r ₁ <r ₂ <... <r _max ) are arranged, wherein the cooling holes of different arrangement circles in the radial direction with each other or offset from each other , In a suitable offset, the bores are located on an array circle centrally below or above the gap between two holes on the adjacent array circle. Sufficient for the temperature gradient in the radial direction and suitable for the stability of the shaft body are decreasing diameters of the cooling holes on the arrangement circles from outside to inside. Further embodiments are possible and practicable, for example a decreasing number of cooling holes on the arrangement circles from outside to inside.

Although according to the invention a strong and rapid cooling of the shaft is intended in its outer region for the removal and mounting of the bandage, in special cases a strong decrease in temperature radially from the inside to the outside can have negative effects on the shaft material, for example. This can be particularly in phases in which, for example, unforeseen, delays the process of mounting the heated bandage. An embodiment of the invention therefore provides that centrally through the shaft a central cooling bore is provided for the flow through with gaseous or liquid coolant. If necessary, this cooling in the center of Wave are counteracted to a possibly too high temperature gradient. This can also prove to be advantageous if the shaft in turn is assembled from a plurality of concentric hollow cylinders, the non-positive connection would solve at excessive temperature gradients over long periods.

In a further embodiment of the invention, cooling tubes for guiding the coolant are arranged in the cooling bores. As a result, a possibly occurring over long periods thermal-chemical change of the material of the shaft in the region of the walls of the cooling holes is prevented. However, the thermal conductivity of the cooling tubes does not affect the actual cooling effect.

The construction of the grinding roller according to the invention is aimed at being able to carry out simple, rapid and material-saving procedures for disassembling (pulling) or mounting (mounting) bandages on or on shafts in grinding rolls which have a large roll diameter, in particular a large shaft diameter exhibit. For such a roll according to the invention, an inventive method for separating bandage and shaft is provided, which is characterized by the following steps: heating the bandage by external heat supply for thermal expansion of the bandage, thereby cooling the shaft with a cooling medium flowing through the cooling holes and pulling off the bandage in the longitudinal axis defined by the axis of rotation of the shaft. If, for example, due to wear, the bandage is to be removed from the shaft of the grinding roller according to the invention, a dilation of the bandage due to thermal expansion is effected, as is previously known, by rapid, very intensive heat input from the outside to the bandage. At the same time, if necessary already begun earlier, a cooling of the shaft is made so that it does not expand in terms of their outer diameter also to a relevant extent. Cooling by supplying a coolant in the center of the shaft is not sufficient for large shaft diameters. An effective and sufficiently rapid, ie even before entry thermically effected, sustainable material changes (in particular phase transformations By steel) solution of the frictional connection of shaft and thermally shrunk bandage is rather achieved in that the shaft is cooled in its outer regions, ie near the joining surface to the bandage. For this purpose, coolant is passed through the inventively arranged in the outer region of the shaft cooling holes. Due to this cooling in the vicinity of the joining surface, there is at most a very low heat input into the shaft, so that no such thermal expansion as in the bandage takes place. Bandage and shaft separate from each other so that the bandage can be pulled in the axial direction of the shaft. Due to the cooling arranged in the outer shaft region and an approximate compensation of the cooling effect by the heating effect due to the heated bandage, under normal circumstances, hardly any temperature-induced material expansions will advantageously occur in the center of the shaft.

Also, for the reverse process, the mounting or thermal shrinkage of a bandage on a shaft, the structure of the grinding roller according to the invention with the characteristics of the shaft allows a simple and quickly carried out process. Bandage and shaft must of course be given here in a size ratio, which leads to a well-established, non-positive connection in the known thermal shrinking. The skilled person will make a suitable interference fit here, taking into account the specific thermal expansion behavior of the materials involved, so choose a bandage inside diameter, which is slightly smaller at ambient temperature than the outer diameter (joint diameter) of the shaft. The inventive method for non-positive connection of the bandage and the shaft is characterized by heating the separately present bandage, cooling the shaft with a coolant flowing through the cooling holes and by pulling the bandage on the shaft, wherein the wound-up bandage shrinks by cooling or cooling on the shaft , The cooling of the bandage is advantageous before the process of winding and is continued during this. As with the procedure the removal of cooling by means of the present invention in the outer region, near the joining surface arranged cooling holes for only a small heat input into the shaft, so that it does not expand and the heated, thus extended bandage can be striped in the axial direction over the shaft. By cooling, the bandage contracts and it results in a non-positive connection. This shrinkage can be accelerated by continuous cooling of the shaft and possibly cooling from the outside, which makes the expert so that the desired material properties are retained or adjust.

In both methods, it has been shown that even with large shaft diameters by the cooling according to the invention such rapid removal or mounting of the bandage can be carried out that occur in the typical steels used before completion of the process still no adverse phase transformations. With the cooling close to the joining surface, it is thus possible to influence the material and its effect on phase and structure formation in the materials involved.

The methods of peeling and winding can be performed in exactly the same way, when several smaller bandages are arranged side by side in the axial direction. Are in the bandage hard body (pins, plates, etc.) applied as a profile body to form a wear-protective layer, so these are deviating Temperaturausdehnungsverhalten usually in a known manner (turning, grinding, etc.) before removing the bandage to remove.

Fig. 1

die Welle einer erfindungsgemäßen Mahlwalze in schematischer Seitenansicht;

Fig. 2

einen Querschnitt durch die Mahlwalze mit Lage der Kühlbohrungen;

Fig. 3

einen Querschnitt durch die Mahlwalze im Ausführungsbeispiel mit zwei Anordnungskreisen.

The invention will be explained in more detail with reference to the following figures. It shows:

Fig. 1

the shaft of a grinding roller according to the invention in a schematic side view;

Fig. 2

a cross section through the grinding roller with location of the cooling holes;

Fig. 3

a cross section through the grinding roller in the embodiment with two arrangement circles.

In FIG. 1 is shown in side view, the shaft 1 of a grinding roller 2 according to the invention, as is typical for use in high-pressure roller presses (roller presses). The grinding roller 2 consists of the shaft 1 and a not shown here, by thermal shrinkage frictionally connected to the shaft 1, wear-resistant bandage 3. The shaft 1 is rotatable and rotationally symmetrical to a rotational axis 4 and tapers towards the ends in favor of Storage, the lower weight and the easier removal and mounting a bandage 3 from or to the middle, the largest diameter possessing portion of the shaft 1. Schematically drawn are two cooling holes 5, which are arranged according to the invention in the outer region of the shaft 1. They traverse in the longitudinal direction of the shaft 1 with open ends on both sides, so that coolant can be passed through the cooling holes 5, when applied to the shaft 1 by thermal shrinkage in the process according to the invention, a bandage 3 and frictionally connected to the shaft 1 or a shrunk bandage 3 is subtracted from the shaft 1 in the method according to the invention. In the cooling holes 5 while cooling tubes can be introduced (not shown). The location of the cooling holes 5 in the outer region of the shaft 1 allows a fast, simple and gentle material producing a sufficient temperature difference between shaft 1 and heated from the outside bandage 3, so that a comparatively rapid removal or mounting of the bandage 3 by the different thermal expansion of Shaft 1 and bandage 3 is transported.

FIG. 2 illustrates in a direction perpendicular to the axis of rotation 4 cross-section through a grinding roller 1 according to the invention in the section where the shaft 1 is enclosed by the bandage 3, schematically the geometric relationships of the position of the cooling holes 5. In the illustrated embodiment the cooling holes 5 arranged symmetrically on an imaginary arrangement circle 6. The cooling holes 5 do not intersect the joining surface 7 between the shaft 1 and the bandage 3, but are advantageously arranged in the outer region of the shaft 1. According to the invention, they are arranged in an imaginary, here symbolically with its inner circumference drawn circular ring 8, 8 ', the center of which lies on the axis of rotation 4 to the advantage of the method of removing and pulling the bandage 3. The circular ring 8, 8 'has the same radius as the outer radius r _max as the shaft (r _w ). Good cooling properties for the methods have been found in measurements for an inner radius r _{min of} the annulus 8, which is equal to one third of the outer radius r _max . Especially with large grinding rolls, however, an inner radius r ' _min is preferred for which r' _min = 2/3 r _max . The inner circumference of this narrower circular ring 8 'is shown symbolically.

In FIG. 3 we in a cross-sectional representation (corresponding FIG. 2 ) An embodiment shown in which the cooling holes 5 on two imaginary concentric arrangement circles 6, 6 'with the radii r ₁ and r ₂ within the imaginary circular ring 8, 8' (not shown) are arranged. Several such arrangement circles 6, 6 'can be advantageous for large grinding rolls 2 for a more even cooling without excessive' perforation 'of the shaft 1 along only one circular line. In the exemplary embodiment, the cooling bores 5 of the two arrangement circuits 6, 6 'are offset from one another for reasons of uniform cooling. <I> LIST OF REFERENCES </ i> 1 wave 2 grinding roll 3 bandage r _max outer radius (circular ring) 4 axis of rotation r _min , r ' _min inner radius (circular ring) 5 cooling hole 6, 6 ' arrangement circle r _w Radius of the shaft 7 joining surface r ₁ , r ₂ Radius (arrangement circle) 8, 8 ' Circular ring (geometric)

Claims (7)

1. Grinding roller (2) of a high-compression roller press, having

   - a shaft (1), wherein the shaft (1) is rotationally symmetrical in relation to a rotation axis (4); and

   - at least one wear-resistant strap (3), wherein the shaft (1) and the at least one strap (3) are mutually coaxial, and wherein the strap (3) in a longitudinal portion of the shaft (1) is shrunk onto the shaft (1) in a force-fitting manner,

   characterized in that
   the shaft (1) for the perfusion with a gaseous or liquid coolant has a plurality of cooling bores (5) that are continuous through the shaft (1) in the axial direction,
   wherein the cooling bores (5) are disposed in the external region of the shaft (1) such that said cooling bores (5) in the case of a cross section through the shaft (1) that is performed perpendicularly to the rotation axis (4) in that region of the longitudinal portion of the shaft (1) that has the strapping (3) penetrate the interior of an imaginary geometric annulus (8, 8'), the center of the latter lying on the rotation axis (4), the external radius r_max of said annulus (8, 8') being equal to the external radius r_w of the shaft (1), and the internal radius r_min of said annulus (8, 8') being one third of the external radius (1/3 r_max), preferably two thirds of the external radius (2/3 r_max).
2. Grinding roller (2) according to Claim 1,
   characterized in that
   the cooling bores (5) in a cross section through the shaft (1) that is performed perpendicularly to the rotation axis (4) are disposed so as to be symmetrically distributed on an arrangement circle (6, 6') having the center on the rotation axis (4) and the radius r₁ which lies between the external and the internal radius of the penetrated geometric annulus (8, 8') : (r_min < r₁ < r_max.
3. Grinding roller according to Claim 1,
   characterized in that
   the cooling bores (5) in a cross section through the shaft (1) that is performed perpendicularly to the rotation axis (4) are disposed so as to be symmetrically distributed across at least two concentric arrangement circles (6, 6') having the center on the rotation axis (4) and radii (r₁, r₂, ...) which lie between the external and the internal radius of the penetrated geometric annulus (8, 8'): r_min < r₁ < r₂ < ... < r_max,
   wherein the cooling bores (5) of different arrangement circles (6, 6') in the radial direction are mutually aligned or aligned so as to be mutually offset.
4. Grinding roller (2) according to one of Claims 1 to 3,
   characterized in that
   a central cooling bore (5) for the perfusion with gaseous or liquid coolant is provided so as to be axially centric through the shaft (1).
5. Grinding roller (2) according to one of Claims 1 to 4,
   characterized in that
   cooling pipes for routing the coolant are disposed in the cooling bores (5).
6. Method for separating a strap (3) and a shaft (1) in the case of a grinding roller (2) according to one of Claims 1 to 5
   characterized by

   - heating the strap (3) by supplying external heat for a thermal expansion of the strap (3);

   - cooling of the shaft (1) performed herein by way of a coolant that perfuses the cooling bores (5) and

   - stripping the strap (3) from the shaft (1) in the longitudinal direction as established by the rotation axis (4).
7. Method for connecting a strap (3) and a shaft (1) in a force-fitting manner so as to form a grinding roller (2) according to one of Claims 1 to 5, wherein the strap (3) and the shaft (1) in terms of the diameters thereof are embodied in an interference fit,
   characterized by

   - heating the strap (3) that is present separately;

   - cooling the shaft (1) by way of a coolant that perfuses the cooling bores (5); and

   - fitting the strap (3) onto the shaft (1), wherein the strap (3) that has been pull-fitted shrinks onto the shaft (1) by cooling down or cooling.

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