Roller body produced by shrink fitting

Abstract

The present invention relates to a roller body (10) having an inner roller cylinder (20) and an outer roller cylinder (30) separate from the inner roller cylinder (20), characterized in that a friction-increasing layer (40) is arranged between the inner roller cylinder (20) and the outer roller cylinder (30).

Description

[0001] Roller bodies produced by shrink-fitting

[0002] The invention relates to a roller body which is made up of two cylindrical bodies joined together.

[0003] While the interior of the roller body houses the bearings for the shaft and thus the rotational drive, and is itself hardly subject to wear, the surface, for example in a crusher or mill, is often heavily worn over its service life. Therefore, during refurbishment, a roller can be ground down accordingly, and a new cylinder can be slid over the core to create a refurbished roller body with an intact surface. For this reason, many roller bodies are composed of two cylindrical components. Typically, the outer cylinder is heated before being slid over the inner cylinder. Upon cooling, the outer cylinder shrinks, creating a positive-locking connection between the outer and inner cylinders. Such systems are known and commonly used as tire-on-tire. The load must be transferred through this shrink fit, and any movement of the cylinders relative to each other must be prevented.For the connection to be stable and the roller body to behave as a single unit, the inner diameter of the outer cylinder must be slightly smaller than the outer diameter of the inner cylinder. This creates stresses, particularly in the outer cylinder, which can lead to problems and, in the worst case, breakage.

[0004] Instead of heating the outer cylinder, the inner cylinder can also be cooled, which leads to the same result. For simplicity, the term "shrinking" is used for both methods, although this is only technically correct for the first case.

[0005] From DE 19702 161 A1 a roller and a method for manufacturing a roller are known.

[0006] From EP 1 300 485 A1, a force-transmitting surface layer and a method for its production are known. From US 2025 / 067288 A1, a coupling for connecting the ends of two rotatable shafts is known.

[0007] A roller body for a high-pressure roller mill is known from DE 102010060236 A1.

[0008] From EP 2498911 81 a grinding roller of a roller mill is known.

[0009] The object of the invention is to reduce the stress in the roller body after shrinking.

[0010] This problem is solved by the roller body with the features specified in claim 1 and by the method with the features specified in claim 8. Advantageous embodiments are described in the dependent claims, the following description, and the drawings.

[0011] The roller body according to the invention comprises an inner roller cylinder and an outer roller cylinder separate from the inner roller cylinder. These do not form an actual material unit, but are held together solely by the forces acting upon them, thus forming a mechanically connected unit. This also means that, theoretically, the inner roller body could be movable relative to the outer roller body. Only the shrink-fit process creates a force-fit connection that prevents this. The inner roller cylinder can encompass the shaft, which is particularly relevant when reconditioning an existing roller body, or it can be a hollow cylinder into which a shaft is subsequently inserted, which is preferred for new manufacturing.

[0012] According to the invention, a friction-enhancing layer is arranged between the inner and outer roller cylinders. This friction-enhancing layer contains particles. These particles have a larger diameter than the distance between the inner and outer roller cylinders under normal conditions (at ambient temperature). This means that during assembly, the particles are pressed into the inner and / or outer roller cylinders at specific points. Thus, during assembly, the particles cause a deformation of the inner and outer roller cylinders, albeit only on a microscopic level. This creates positive-locking connections between the inner and outer roller cylinders, enabling very efficient power transmission. As a result, the diameter difference can be smaller compared to current designs without a friction-enhancing layer.The diameter difference here refers to the value by which the inner diameter of the outer roller cylinder is smaller than the outer diameter of the inner roller cylinder. This reduces the stress in the roller cylinder, lowers the risk of breakage, and prevents relative movement of the inner roller cylinder to the outer roller cylinder despite the lower tension force due to increased friction. Since significantly lower tension forces occur in the outer roller cylinder, other wear-resistant surfaces become possible that would be damaged by the tension forces in the classic tire-on-tire solution and are therefore not feasible using a tire-on-tire solution according to the current state of the art. This applies particularly to studs and especially to full-surface ceramic surfaces, which are not feasible with previous systems due to the tension. However, these are common, for example, in one-piece roller bodies.Thus, the new stress-reduced manufacturing process enables particularly wear-resistant surfaces, even in the tire-on-tire process, making them suitable for applications such as fine grinding, for example, in the cement industry. Fine grinding involves significantly higher pressing pressures due to the much finer grinding process. These high pressures, however, can lead to damage if stresses occur within the roller body. Therefore, surface wear protection is crucial, and the use of ceramic surfaces offers a significant increase in service life for fine grinding applications, particularly in cement production.The invention thus enables the use of roller bodies, either in initial production or in reconditioning using the tire-on-tire process, with a hard surface known, for example, from iron ore processing, also in the cement sector for high-pressure fine grinding. The roller body produced according to the invention therefore differs from previous ones, which leads to new applications. The ceramic layer on the outer roller cylinder can, for example, consist of tungsten carbide. Preferably, and for example, the outer roller cylinder is produced by casting, whereby the ceramic part is produced first and then the metallic part is cast into the ceramic cake, so that a strong and permanent bond is created by the interlocking effect.This outer roller cylinder produced by casting can then be used according to the invention to produce a low-stress roller body, so that the wear-resistant surface, in particular ceramic, remains undamaged and can also withstand operation for fine grinding.

[0013] In a further embodiment of the invention, the friction-enhancing layer comprises particles of diamond and / or carbide. These can be either pure or, preferably, embedded in a substance that adheres at least temporarily, for example, a varnish or adhesive, in order to avoid waste during production. Diamond and carbides, for example, and especially tungsten carbide, are very hard. This causes them to essentially "cut" into the roller cylinders, thus creating a kind of bridge between the two roller cylinders, which prevents or at least significantly hinders rotation relative to each other. Therefore, it is advantageous to use a material with very high hardness.

[0014] In a further embodiment of the invention, the roller body is composed of three parts: an inner shaft, the inner roller cylinder, and the outer roller cylinder. In this embodiment, the friction-enhancing layer can be arranged not only between the inner roller cylinder and the outer roller cylinder, but optionally also between the shaft and the inner roller cylinder.

[0015] In a further embodiment of the invention, the inner and outer roller cylinders have a cylindrical surface at their contact surface. This means that a minimal displacement of the inner roller cylinder relative to the outer roller cylinder does not result in any change in the tension. Furthermore, the cylindrical surfaces can be machined very efficiently by rotary machining. In another embodiment of the invention, the inner and outer roller cylinders have a conical surface at their contact surface. This allows manufacturing variations to be compensated for by a minimal lateral displacement of the roller cylinders relative to each other, in order to achieve the precisely desired diameter difference.

[0016] In a further embodiment of the invention, the surface of the outer roller cylinder has studs. Studs, as mostly ceramic wear-resistant elements, have proven very effective and, due to the reduced stress according to the invention, can also be used non-destructively in a tire-on-tire roller body.

[0017] In a further embodiment of the invention, the surface of the outer roller cylinder has a ceramic wear layer. A full-surface ceramic layer as a wear-resistant wear layer is only made possible by the reduced stress in a tire-on-tire roller body according to the invention.

[0018] In a further embodiment of the invention, the surface of the outer roller cylinder has a hardfacing weld.

[0019] In another aspect, the invention relates to a method for manufacturing a roller body, wherein the method comprises the following steps:

[0020] a) Providing an inner roller cylinder and an outer roller cylinder, b) Coating the inside of the outer roller cylinder and / or the outside of the inner roller cylinder with a friction-enhancing layer, wherein the friction-enhancing layer (40) comprises particles, wherein the particles have a larger diameter than the distance between the inner roller cylinder (20) and the outer roller cylinder (30) at ambient temperature, c) Heating the outer roller cylinder and / or cooling the inner roller cylinder,

[0021] d) Joining the inner roller cylinder and the outer roller cylinder at different temperatures,

[0022] e) Bringing the roller body to ambient temperature. The two alternatives shown—a heated outer roller cylinder, which increases in diameter, and a cooled inner roller body, which decreases in diameter—are equivalent. Both methods create a diameter difference, allowing the two roller cylinders to be pushed together. Both methods are currently used and are considered state of the art. The novel aspect is the coating in step b), which makes it possible to minimize the diameter difference and thus reduce the probability of failure. The coating in step b) can be applied, for example, by spraying, splashing, brushing, flame treatment, or blackening. The coating does not need to meet the requirements of a permanent coating.The coating merely serves to provide the friction-enhancing layer, which is then permanently fixed by the shrinking process in step e). Crucially, in step e), the particles, due to their size, are pressed into the surface of the inner and outer roller cylinders. This reshapes the surface of the inner and outer roller cylinders at a microscopic level, creating a positive-locking connection between them in step e). Furthermore, the coating does not need to be applied across the entire surface, especially not completely. It is sufficient, for example, to apply a distribution of friction-enhancing particles as evenly as possible to create the friction-enhancing layer.

[0023] In a further embodiment of the invention, in step b) particles of diamond or carbide, in particular tungsten carbide, are applied. For temporary stabilization, this can be achieved, for example, with a varnish, an adhesive, or even wax, which is then removed by heat during shrinkage.

[0024] In a further embodiment of the invention, the outer roller cylinder is first manufactured in step a). This determines the inner diameter of the outer roller cylinder. The inner roller cylinder is then manufactured by grinding to match the inner diameter of the outer roller cylinder. This has the advantage that, in the conventional reconditioning of roller bodies, the outer roller cylinders can be manufactured in advance with the new outer surface already formed. The rollers to be reconditioned are then only ground to the required outer diameter during the reconditioning process, thereby accelerating the reconditioning and reducing the service life.

[0025] In another embodiment of the invention, the inner roller cylinder and / or the outer roller cylinder are forged.

[0026] In a further embodiment of the invention, the inner roller cylinder and / or the outer roller cylinder are cast.

[0027] The method according to the invention is explained in more detail below with reference to an embodiment shown in the drawings.

[0028] Fig. 1 prefabricated outer roller cylinder

[0029] Fig. 2 Old roller body

[0030] Fig. 3 inner roller body

[0031] Fig. 4 inner roller body with applied friction-enhancing layer

[0032] Fig. 5 heated outer roller body

[0033] Fig. 6 Assembling

[0034] Fig. 7 Roller body

[0035] The illustrations are shown in cross-section, purely schematic and not to scale, and serve only for clarification.

[0036] Fig. 1 shows a prefabricated outer roller cylinder 30. This has the wear surface for the grinding or crushing process on its outer surface. Fig. 2 shows a used roller body 11, which already has a reduced diameter due to wear on its outer surface. Corresponding to the inner diameter of the outer roller cylinder shown in Fig. 1, the used roller body 11 is reduced to a diameter shown in Fig.

[0037] The inner roller body 20 shown in Fig. 3 is ground down and coated with a friction-enhancing layer 40, which contains, for example, tungsten carbide particles or small industrial diamonds, as shown in Fig. 4. The outer roller cylinder 30 is heated, causing it to expand as shown in Fig. 5 (clearly exaggerated), thereby increasing the inner diameter so that the inner roller body 20 can be inserted, as shown in Fig. 6. After cooling, the finished roller body 10 shown in Fig. 7 is obtained.

[0038] Reference sign

[0039] 10 roller bodies

[0040] 11 old roller bodies

[0041] 20 inner roller cylinders

[0042] 30 outer roller cylinders

[0043] 40 friction-enhancing layer

Claims

Patent claims 1. Roller body (10) with an inner roller cylinder (20) and an outer roller cylinder (30) separated from the inner roller cylinder (20), characterized in that a friction-enhancing layer (40) is arranged between the inner roller cylinder (20) and the outer roller cylinder (30), wherein the friction-enhancing layer (40) has particles, wherein the particles have a larger diameter than the distance between the inner roller cylinder (20) and the outer roller cylinder (30).

2. Roller body (10) according to claim 1, characterized in that the friction-enhancing layer (40) comprises particles of diamond and / or carbide.

3. Roller body (10) according to one of claims 1 to 2, characterized in that the inner roller cylinder (20) and the outer roller cylinder (30) have a cylindrical surface at the contact surface.

4. Roller body (10) according to one of claims 1 to 2, characterized in that the inner roller cylinder (20) and the outer roller cylinder (30) have a conical surface at the contact surface.

5. Roller body (10) according to one of claims 1 to 4, characterized in that the surface of the outer roller cylinder (30) has studs.

6. Roller body (10) according to one of claims 1 to 4, characterized in that the surface of the outer roller cylinder (30) has a ceramic wear layer.

7. Roller body (10) according to one of claims 1 to 4, characterized in that the surface of the outer roller cylinder (30) has a hardfacing weld.

8. Method for manufacturing a roller body (10), the method comprising the following steps: a) providing an inner roller cylinder (20) and an outer roller cylinder (30), b) Coating the inside of the outer roller cylinder (30) and / or the outside of the inner roller cylinder (20) with a friction-enhancing layer (40), wherein the friction-enhancing layer (40) comprises particles, the particles having a larger diameter than the distance between the inner roller cylinder (20) and the outer roller cylinder (30) at ambient temperature, c) Heating the outer roller cylinder (30) and / or cooling the inner roller cylinder (20), d) Joining the inner roller cylinder (20) and the outer roller cylinder (30) at different temperatures, e) Bringing the roller body (10) to ambient temperature.

9. Method according to claim 8, characterized in that the coating in step b) is carried out by spraying, splashing, brushing, flame coating or bluing.

10. Method according to one of claims 8 to 9, characterized in that in step b) particles made of diamond or carbide are applied.

11. Method according to one of claims 8 to 10, characterized in that, to provide in step a), the outer roller cylinder (30) is manufactured, wherein the inner roller cylinder (20) is then manufactured by grinding according to the inner diameter of the outer roller cylinder (30).

12. Method according to one of claims 8 to 11, characterized in that the inner roller cylinder (20) and / or the outer roller cylinder (30) are forged.

13. Method according to one of claims 8 to 11, characterized in that the inner roller cylinder (20) and / or the outer roller cylinder (30) are cast.

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