Abrasive tool and use of such an abrasive tool

Abstract

An abrasive tool, including an abrasive carrier (1) having a shaft (2) for connecting the abrasive carrier (1) to a driving device for rotatably driving the abrasive carrier (1) about a longitudinal axis (X) and having a core (3) connected to an axial end (4) of the shaft (2), and an abrasive article (15) having a surface (16) being circumferentially closed about the longitudinal axis (X) and enclosing a cavity (17) extending along the longitudinal axis (X), wherein the core (3) is accommodated at least partially in the cavity (17), and wherein the core (3) includes a material mixture which includes a plastic with a heat-conductive filler, wherein the plastic is foamed, and wherein the filler has a thermal conductivity greater than 35 watts per meter and per Kelvin.

Claims

1. An abrasive tool comprising: an abrasive carrier having a shaft for connecting the abrasive carrier to a driving device for rotatably driving the abrasive carrier about a longitudinal axis and having a core connected to an axial end of the shaft, and an abrasive article having a surface being circumferentially closed about the longitudinal axis and defining a cavity extending along the longitudinal axis, wherein the core is accommodated at least partially in the cavity, and wherein the core includes a material mixture comprising a plastic with a heat-conductive filler, wherein the plastic is foamed, and wherein the filler has a thermal conductivity greater than 35 watts per meter and per Kelvin.

2. Abrasive tool according to claim 1, wherein the volume of the foamed plastic is 70% to 95% of the total volume of the core, wherein the volume of the filler and the volume of at least one optional functional additive in sum is at most 30% of the total volume of the core.

3. Abrasive tool according to claim 1, wherein the core includes 25 to 75 weight percent of the filler and 0 to 10 weight percent of at least one functional additive, wherein the remainder of the core includes the plastic and unavoidable impurities.

4. Abrasive tool according to claim 3, wherein the at least one functional additive is selected from the group comprising thermochromic color pigments, anti-bacterial agents, anti-fungicidal agents, friction modifying agents.

5. Abrasive tool according to claim 1, wherein the plastic has a density of 700 to 1250 kilograms per cubic meter and/or a Shore hardness A of 30 to 90.

6. Abrasive tool according to claim 1, wherein the plastic is a one-component plastic or a two-component plastic.

7. Abrasive tool according to claim 1, wherein the plastic is selected from the group comprising polyurethane, elastic polymers, silicone, synthetically produced rubber and natural rubber.

8. Abrasive tool according to claim 1, wherein the filler is inorganic.

9. Abrasive tool according to claim 1, wherein the filler is selected from the group comprising silver, copper, silicon carbide and carbon nanotubes.

10. Abrasive tool according to claim 1, wherein the filler is a mixture of different heat-conductive materials.

11. Abrasive tool according to claim 1, wherein the filler is homogeneously distributed in the core.

12. Abrasive tool according to claim 1, wherein a radially outer portion of the core comprises a higher concentration of the filler than the rest of the core.

13. Abrasive tool according to claim 1, wherein the shaft is made of a material having a thermal conductivity greater than 35 watts per meter and per Kelvin.

14. Abrasive tool according to claim 1, wherein the shaft comprises heat transfer means, which are formed on the shaft in a shaft area arranged outside the core.

15. Abrasive tool according to claim 1, wherein at least one radially projecting flange is arranged at the shaft, wherein the flange is made of a material which has a thermal conductivity of greater than 35 watts per meter and per Kelvin.

16. Abrasive tool according to claim 15, wherein an outer side of the flange is arranged in a plane together with an end face of the core facing the shaft.

17. Abrasive tool according to claim 1, wherein the abrasive carrier comprises a coating which is applied onto the outer surface of the core, wherein the coating comprises thermochromic color pigments and/or anti-bacterial agents and/or an anti-fungal agents.

18. Abrasive tool according to claim 1, wherein an outer surface of the core is shaped at least partially complementary to the surface of the abrasive article defining the cavity.

19. Abrasive tool according to claim 1, wherein the outer surface of the core is a lateral surface being closed in the circumferential direction about the longitudinal axis.

20. Abrasive tool according to claim 1, wherein the abrasive article comprises thermochromic colorant for determining an external surface temperature of an abrasive layer of the abrasive article.

21. An abrasive tool comprising: an abrasive cap having a surface being circumferentially closed about the longitudinal axis and defining a cavity therein which extends along the longitudinal axis; an abrasive carrier including a core provided at least partially in the cavity of the abrasive cap and a shaft extending from the core for connecting the abrasive carrier to a driving device for rotatably driving the abrasive carrier about the longitudinal axis, wherein the core includes a material mixture comprising a plastic with a heat-conductive filler, wherein the plastic is foamed, and wherein the filler has a thermal conductivity greater than 35 watts per meter and per Kelvin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments are described in the following using the figures.

(2) FIG. 1 shows a side view of an abrasive carrier according to the invention; and

(3) FIG. 2 shows a side view of an abrasive tool according to the invention with the abrasive carrier of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows an abrasive carrier 1 according to an embodiment of the invention. The abrasive carrier 1 comprises a metal shaft 2 and a core 3 made of a material mixture comprising a plastic with a heat-conductive filler and, here, other functional additives.

(5) The shaft 2 has an elongated, pin-like basic shape with a front axial end 4 and a rear axial end 5, and defines a longitudinal axis X. The rear axial end 5 of the shaft 2 serves to connect the abrasive carrier 1 to a driving device (not shown) to rotate the abrasive carrier 1 about the longitudinal axis X. For this, the shaft 2 can be clamped, for example, in a chuck of the driving device. To securely hold the core 3 on the metal shaft 2, the shaft 2 has a roughened, in particular ribbed surface along the front axial end 4 that is covered by the core 5. In addition, on the shaft 2 a radially projecting flange 6, which has here a ring-like closed shape, is arranged. The flange 6 is also made of metal, and is, by way of example, as well as the shaft 2, made of steel, for instance. An outer side 7 of the flange 6 facing the rear axial end 5 of the shaft 2 is arranged in a plane E together with an end face 8 of the core 3 facing the shaft 2, i.e. the flange 6 is flush with the core 3. Furthermore, the shaft 2 has heat transfer means 10 within a shaft area 9 of the shaft 2 that is arranged outside the core 3. The heat transfer means 10 are, here, embossings which increase the surface area and thus the emission surface area of the shaft 2 in the shaft area 9. The rear axial end 5 of the shaft 2 has an even surface. Starting at the rear axial end 5, the beginning of the embossings 10 defines a clamping mark 11 indicating to the user the optimum clamping depth in the driving device.

(6) The core 3 is rotationally symmetrical to the longitudinal axis X and has a solid body which, by way of example, has a cylindrical section and a hemispherical section. Alternative geometries are also possible. The shaft 3 is accommodated in the cylindrical section of the core 3. The material mixture of the core 3 is, here, foamed polyurethane, which is cured closed-pore. The foam is formed by gaseous bubbles enclosed by solid walls. Depending on the application for which the abrasive carrier 1 is intended, e.g. for metal-, plastic- or wood-processing or for the treatment of patients, the plastic can be provided with different properties. For example, the plastic can have a density of 700 to 1250 kilograms per cubic meter. Furthermore, the plastic can have a Shore hardness A of 30 to 90.

(7) In the material mixture of the core 3 also the heat-conducting filler is provided, mixed with the plastic and distributed as homogeneously as possible in the core 3. In FIG. 1, the filler is, together with the other functional additives, indicated by the dots shown within in the core 3, wherein the dots are for the sake of clarity marked only once with the reference sign 12. The filler may be inorganic, in particular metal or mineral. For example, the filler can be silver, copper or silicon carbide. The filler may also include carbon nanotubes. Such fillers have a coefficient of thermal conductivity A of more than 35 W/mK. The fillers thus have a significantly higher thermal conductivity than the plastic, which, using foamed polyurethane as an example, has a coefficient of thermal conductivity of about 0.04 W/mK. In addition, the shaft 2 and the flange 6 are also made of a material, here of steel, which has a thermal conductivity of more than 35 W/mK and that is significantly higher than the thermal conductivity of the plastic.

(8) In addition, the material mixture of the core 3 contains the functional additives. For one thing, the additives used here include thermochromic color pigments, which indicate to the user by color change that a defined temperature or a critical temperature range has been reached. The use of thermochromic color pigments in the core 3 of the abrasive carrier 1 is in particular useful when abrasive articles are used which only partially cover the core 3. For example, this could be a cylindrical abrasive sleeve arranged on the cylindrical section of the core 3.

(9) Furthermore, the functional additives can influence the friction behavior of an outer surface 13 of the core 3. By this, the coefficient of static friction can be increased. Furthermore, anti-bacterial and anti-fungal additives, for instance silver or colloidal silver, are provided.

(10) Thus, the core consists of, by way of example, 25 to 75 weight percent of the filler and 0.5 to 10 weight percent of the functional additives, wherein the remainder of the core 3 consists of the plastic, whereby marginal impurities cannot be excluded.

(11) A coating 14 has been applied to the outer surface 13 of the core 3 which, in this case, contains anti-bacterial and anti-fungicidal agents to provide a starting product for the treatment of patients that is as hygienic as possible. In principle, the coating 14 could also contain thermochromic color pigments.

(12) FIG. 2 shows an abrasive tool according to the invention, which shows besides the abrasive carrier 1 of FIG. 1 an exchangeable abrasive article 15 that is pulled over the core 3.

(13) The abrasive article 15 has a surface 16 that is circumferentially closed about the longitudinal axis X and encloses a cavity 17 extending along the longitudinal axis X. The abrasive article 15 is shown, by way of example, as a seamless abrasive cap. The core 3 of the abrasive carrier 1 already described in connection with FIG. 1 is accommodated in the cavity 17.

(14) The outer surface 13 is complementary to the surface 16 and is designed as a lateral surface that is circumferentially closed around the longitudinal axis X. Thus, the surface 16 of the abrasive article 15 lies flat on the outer surface 13 of the core 3, so that the exchangeable abrasive article 15 is held only by the static friction force on the core 3.

(15) On a side of the abrasive article 15 facing away from the core 3, an abrasive layer 18 is arranged which has abrasive grains bound in a binder, in particular resin. In the grinding layer 18, here, thermochromic color pigments are provided to determine an external surface temperature of the abrasive article 15, in particular of the abrasive layer 18.

(16) When the abrasive tool is in operation, it is rotated about the longitudinal axis X by the driving device. During grinding operation, the friction between the abrasive article 15 and the object to be treated generates frictional heat, which is distributed into the core 3 by the heat-conducting fillers. The core 3 can dissipate the absorbed thermal energy via the end face 8 of the core 3 that is not covered by the abrasive article 15. The metal flange 6 as well as the metal shaft 2, especially due to the heat transfer means 10, support the dissipation of the thermal energy absorbed by the core 3 into the environment.

REFERENCE SIGNS LIST

(17) 1 abrasive carrier 2 shaft 3 core 4 axial end 5 axial end 6 flange 7 outer side 8 end face 9 shaft area 10 heat transfer means 11 clamping mark 12 fillers and functional additives 13 outer surface 14 coating 15 abrasive article 16 surface 17 cavity 18 abrasive layer E plane X longitudinal axis