HK40027603B - Abrasive tool and use of such an abrasive tool - Google Patents

Description

The invention relates to a grinding tool with a grinding carrier which has a shaft for connecting the grinding carrier to a drive device for turning the grinding carrier around a longitudinal axis and a core connected to an axial end of the shaft. The invention also covers a grinding tool which has a surface enclosed perpendicularly around the longitudinal axis, enclosing a cavity extending along the longitudinal axis. The core of the grinding carrier is incorporated at least in part in the cavity. The present invention also concerns the use of such a grinding tool.

The grinding tools of this type are known and are used, for example, for metalworking, foot care, manicure or the dental area. The grinding carrier used in the state of the art, also called mandrell, are usually expansion bodies made of slit rubber with a metal frame to connect the grinding carrier with a drive device. The longitudinal slots are intended to insert or remove the perimeter-closed grinding tool, for example a seamless grinding cap or a tread, on which the respective grinding tool is mounted by the accelerator.

The disadvantage is that the rubber material has a low temperature and shape stability, so that the rubber grinding carrier can contract due to the frictional heat generated during grinding. Thus, the desired effect of expansion by the fitting of the slit grinding carrier is partially compensated by the compression of the rubber under heat input. Especially when the grinding tool is pressed against the object to be worked with a high pressure, on the one hand, a high heat development occurs, which causes the rubber grinding carrier to slip again. On the other hand, the number of times the drive of the grinding machine is regularly increased, so that the grinding machine is partially removed from the grinding agent. This is due to the fact that only a relatively high pressure can be applied between the grinding tool and the grinding agent.

The use of metal grinding materials is also known today. These have the advantage of maximum temperature stability. However, they have a higher intrinsic weight and a hard and unyielding surface. In addition, the adhesion between the grinding material and the grinding material is much less than that between metal grinding materials and rubber grinding materials, so that clamping devices are necessary to keep the grinding material securely on the grinding material during rotation.

DE 20 2014 007 228 U1 is a grinding tool with interchangeable grinding rollers. The grinding rollers have a multi-part core with two core sections and a grinder held between the core sections. The hollow cylindrical grinder is made of a solid foam material and has grinding material on its outside. The foam-sub-fed grinding material allows the grinding agent to adapt to the contour of the body part to be treated, such as a fingernail.

US 7.493.670 B1 shows a polishing tool with an abrasive carrier made of an elastic core that is connected to a drive device via a shaft. The elastic core may be made of closed porous polyurethane, with the shaft poured into the core. Over the core may be draped a cotton bag filled with an abrasive or polisher, which can be attached to the abrasive carrier by pulling a cord in a tunnel train.

DE 2411 859 A1 is a potting disc with a hardened core based on resin, the core containing large quantities of metal particles, 40 to 90% by volume of aluminium and/or copper powder and 35 to 2% by volume of tin and/or tin alloy, to increase the thermal conductivity.

FR 2 020 424 A1 reveals a grinding tool such as a grinding wheel, a splitting wheel or a grinding stone with diamond particles as grinding agent. The known grinding tool is essentially to be composed of two parts, namely a grinding part and a carrier. The diamond particles are embedded in a metal phase, where the metal phase has a defined porosity between 10 and 50%. These pores are filled with a resin material. The same resin material is also used to manufacture the carrier. This is to be given to the carrier in a form before the resin material is placed in the pores of the metal phase in the grinding part.

The present invention is intended to provide an improved grinding tool which is easier to handle and which safely prevents heat damage to the grinding support or object to be worked, even with longer grinding cycles.

The invention is based on the assumption that a plastic is heat-insulating and thus allows only short abrasive cycles to prevent heat-induced damage to the abrasive carrier or object to be worked, in particular to a workpiece or a patient's body part to be treated.

The problem is solved by an abrasive carrier of the type mentioned above, where the core consists of a material mixture containing a plastic with a thermal conductive filler, the heat conductivity of which is greater than 35 watts per metre per kelvin. The plastic is foamed, in other words the material mixture of the core contains a plastic-based foaming material. The problem is solved by an abrasive tool of the type mentioned above, where the core of the abrasive carrier consists of a material mixture containing a foamed plastic with a thermal conductive filler, the heat conductivity of which is greater than 35 watts per metre per kelvin.

According to the invention, the entire core is based on a preferably elastic plastic material, which is added to it to increase the thermal conductivity of the heat-conductive filler. This allows the filler to distribute the thermal energy absorbed at the outer surface of the abrasive carrier throughout the core. This causes the outer surface of the abrasive carrier to cool more quickly, so that the frictional heat generated by the operation of the grinding tool on the grinding tool is transported to the core of the grinding tool. This makes longer grinding cycles possible without damaging the object to be worked, the grinding tool or the grinding tool itself. In addition, a significantly higher heat efficiency can be achieved by the overall heat transfer between the grinding tool and the core of the grinding tool. In addition, the average heat transfer between the grinding tool and the grinding tool can be significantly increased by comparison with the average heat transfer between the grinding tool and the grinding tool.

Thermal conductivity describes the ability of a material to transport thermal energy by means of thermal conduction. This is expressed by the thermal number λ in watts per meter and per kelvin (W/mK). It has been shown that a core, for example, made of flexible polyurethane (short: PUR), especially PUR soft foam, can provide a grinding agent carrier that is more pleasant to patients. In principle, the core can also be made of elastic PUR hard foam or another elastic plastic in the foamed or unfoamed state.

Since foam is generally formed from gaseous bubbles enclosed by solid or liquid walls, the foamed plastic has a low intrinsic weight, which significantly reduces the weight of the core compared to an unfoamed plastic. This is advantageous because in this way the weight of the filler, especially if it is a metal or mineral filler, can be partially compensated. The volume of the foamed plastic can be about 70% to 95% of the total core volume, with the volume of the filler and the volume of a solvent additive added, if any, together being no more than 30% of the total volume. Thus, the core of the filler remains more elastic despite the liquid material produced in the core.

In addition to or as an alternative to metal or mineral fillers, carbon nanotubes can also be used, which have a particularly light weight and high conductivity properties. The filler can also be a mixture of various heat-conducting materials. Depending on the requirement of the abrasive carrier, the filler can provide additional heat-transfer properties in addition to the preferred heat-transfer properties in the core. For example, silicon can be used as an additional antibacterial agent, especially when a radiation-resistant additive is added to the core of the patient, but can also have a better effect on the concentration of the remaining silicon.

The most commonly used plastic is polyurethane, but other types of plastic include polyester, silicone, synthetic rubber, and natural rubber. For foamed plastics, it is preferable to use a one- or two-component plastic. Particularly good results have been achieved with two-component plastics, which through chemical reaction of the two components harden more evenly and foam more strongly. Alternatively, the plastic can also be foamed by propellants.

In order to connect the cylindrical shaft to the core, the shaft can be injected or poured into the core. To do this, the shaft can be held in the material mixture during the manufacture of the core. To improve the adhesion strength between the core and the shaft, an adhesive intermediate can be placed on the axial end of the shaft.

In addition, the shaft can be made of a material, in particular metal, which has a higher thermal conductivity than the plastic, in particular a thermal conductivity greater than 35 watts per meter and per Kelvin. This allows the core to cool faster. Especially in a coreless area, that is, in an area of the shaft not covered by the core, the shaft usually has a smooth surface to easily connect the shaft to the drive device, in particular to this energy.The heat transfer media may be in particular embossings, grooves, grooves, raised edges, wings or the like, which increase the surface area of the shaft relative to a smooth surface in order to release thermal energy to the environment. Preferably, the geometry of the flying or turbo-shaped shaft is such that the air flowing in front of the propulsion system and the heat transfer elements are not sliding away during the transfer process.It is also advantageous that the heat transfer media can also be used as an insert aid when connecting the grinding medium carrier to the drive unit, so that the insert area can have a smooth surface, and the start of the heat transfer media, for example ripping, shows the user of the grinding medium carrier the optimum shaft insert depth in the drive unit.

The flange may be made of at least one radially prominent flange, which is made of a material with a higher thermal conductivity than the plastic, in particular a thermal conductivity of more than 35 watts per metre and per Kelvin, which allows the flange to absorb thermal energy and to be released into the environment. The flange may be made of the same material as the shaft or of a material with a higher thermal conductivity than the shaft. The flange may be rounded or perpendicular to the longitudinal axis. A rear end of the flange may be connected to the flange by a frontal axis, in the plane of the frontal axis. This may be done by means of a flange arrangement, in particular on the front end of the flange, with a central or a rear end of the flange, which may be placed on the front end of the flange, with a central or a rear end of the flange, in the front end of the flange, which may be connected to the front axis.

Preferably, the core must be composed of 25 to 75% by weight, in particular 50 to 55% by weight of the filler and 0 to 10% by weight of at least one functional additive, with the rest of the core composed of plastic and unavoidable impurities. The plastic is particularly suitable for polyurethane. The foamed plastic can be closed-porous. The plastic can have a space weight or density of 700 to 1250 kilograms per cubic metre. Furthermore, the plastic can have a shore hardness A of 30 to 90. The shore hardness A is standardized according to ISO 7619-1 and measures the impact/penetration depth of a cone-shaped steel pump in a test tube on a scale of 0 - 100 on a scale of 0.For metalworking, the core is suitable for a plastic with a shore hardness A of 30 to 90, in particular 80 to 80, preferably 70; the core is therefore somewhat more flexible overall, so that when the grinding tool is used, especially on hard edges of a metal workpiece, the risk of the grain of grinding grains from the grinding layer is reduced.The Commission has

According to one aspect of the present invention, the core material mixture may be expected to contain at least one functional additive. This may be at least one functional additive added to the plastic in powder form or liquid form. The at least one functional additive may contain thermochromic color pigments and/or antibacterial and/or antifungicidal agents and/or agents that modify the irritant content. Antibacterial and/or antifungicidal agents may be used primarily in abrasive carriers intended for use on the patient to provide a hygienically appropriate abrasive release device. This may be at least one functional additive, for example, the carbon dioxide or silicon dioxide release agent.

In particular, in metal, wood and plastic processing, the abrasive carrier can often become very hot, so that the object to be worked, the abrasive carrier or the abrasive may be damaged up to the user's fingers. To prevent this from happening, reversible and/or irreversible thermochrome colour pigments may be added to the abrasive carrier, which, by at least one colour change, visually indicate that at least a defined temperature or a critical temperature range has been reached. Thus, the user of the abrasive carrier can be visually shown that the abrasive carrier and/or the abrasive carrier have become too hot. This means, for example, that the effect of the thermochrome, i.e. the change in colour of certain substances, is due to heating.The thermochromic color pigments allow the user to react to overheating by, for example, reducing the pressure, regulating the speed of the drive or breaking the grinding process. The use of the heat-conductive filler can quickly cool the outer surface of the core, and the use of reversible pigments, or irreversible pigments, can also be used as an alternative to the use of coolant.The user can be permanently informed that the abrasive carrier has been operating above the maximum permissible surface temperature, for example, by providing for an irreversible change of colour when the maximum permissible surface temperature is reached. This will permanently indicate the single overheating of the abrasive carrier. Furthermore, irreversible colour pigments can change colour when the specified surface temperature is reached just above the specified room temperature, in order to permanently indicate that the abrasive carrier has been used once after a short abrasive operation. The least one colour change will be sufficiently apparent to the user if the thermochromic effect of the pigment is up to 10 per cent by weight of the pharmaceutical material.

In addition, it may be provided that the abrasive carrier be coated on the surface of the core with the thermochromic colouring pigments and/or antibacterial and/or antifungal agents.

The grinding tool according to the invention has the grinding agent in addition to the grinding agent carrier. The grinding agent is interchangeable at the core. Preferably the grinding agent carrier can be used for several grinding operations, whereas the grinding agent can be a wear product.

The surface of the abrasive is closed in perimeter direction around the longitudinal axis of the abrasive carrier and includes a cavity extending along the longitudinal axis of the abrasive carrier. Thus, the abrasive may have a cylindrical, conical, conical, spherical, cylindrical and semi-shaped, or cap-shaped surface, with other geometric shapes. The abrasive may be a particularly seamless abrasive cap that can be seamlessly attached to the core of the abrasive carrier on the surface.The abrasive material is then held in place by a core, which is then moved to the core by a separate adhesive, which is used only by inserting the core into the core, and the core can be adjusted to the core by adjusting the core adhesive.The abrasive material is preferably made of a flexible material, such as a grinding line, which may be preferably a flexible support material coated with an abrasive material on a grinding side away from the core.

In particular, the core can be made of a closed porous foam material, whereby good adhesion values can be achieved with an open porous foam material as well. Preferably, the maximum external permeability of the foam is equal to or less than the maximum internal permeability of the foam. This makes the foam material more easily deflected from the core, since the results are best against the corrosion of plastic and other heavy materials, and the foam material can be safely stored in the core and the results are better against the corrosion of red and red.

Alternatively to the closed shell surface, the outer surface of the core may be a shell surface, interrupted in perimeter direction around the longitudinal axis. The interruptions may be sliced and may extend in a longitudinal direction defined by the shaft. The interruptions may be cut into the core if necessary after the core is manufactured or may be provided directly during manufacture, for example by casting or spraying a particularly lamellar surface. By applying flying forces acting on the core during the rotation of the abrasive carrier, the core drive can thus continue to slide and push against the surface of the abrasive carrier from within.

In accordance with another aspect, it is envisaged that the abrasive may have reversible and/or irreversible thermochromic dyes to determine an external surface temperature of the abrasive. The user can, similar to the thermochromic dyes added as an additive in the core, by color change indicate the reaching of a defined temperature or a critical temperature range. Especially when the abrasives are further developed as a core of abrasive that completely covers the core, the thermochromic dyes are arranged in a double order in the abrasive.

The grinding tool according to the invention may be used, for example, for metalworking and/or treatment of human body parts, in particular in the context of non-therapeutic or cosmetic treatment of a patient, for example foot care, manicure or dental care.

The following illustrations illustrate the preferred embodiments: Figure 1 shows a side view grinding machine; andFigure 2 shows a side view grinding machine of the invention with the side view grinding machine shown in Figure 1.

The abrasive carrier 1 consists of a metal shaft 2 and a core 3 of a material mixture containing a plastic with a thermal filler and, here, other functional additives.

The shaft 2 has an elongated, pin-like base with a front axial end 4 and a rear axial end 5 and defines a longitudinal axis X. The rear end 5 of the shaft 2 is used to connect the abrasive carrier 1 to an unshown drive device to rotate the abrasive carrier 1 around the longitudinal axis X. For this purpose, the shaft 2 may be tightened, for example, into a tensioner of the drive device.The outer side of the flange 6 facing the rear end of the shaft 2 is in a plane E with a front side facing the shaft 2 facing the front side of the core 3 in a plane E, i.e. the flange 6 closes in a close position with the core 3. Furthermore, the shaft 2 in a shaft section 9 of the shaft 2 located outside the core 3 has heat transfer media 10. The heat transfer media 10 are, here, mouldings which intersect the surface area, or the radiation area, of the shaft 2 in the shaft 9.The rear end of shaft 2 5 has a smooth surface, and starting from the rear end of shaft 5 the beginning of the stamps 10 as the stress mark 11 indicates to the user the optimum stress depth in the drive.

The core 3 is rotationally symmetrical to the X-axis and has a full body, which, as an example, has a cylindrical section and a semicircular section. Alternative geometries are also possible. The shaft 3 is included in the cylindrical section of the core 3. The material mix of the core 3 is, here, foamed polyurethane, which is closed-pore hardened. The foam is formed from gas bubbles enclosed by solid walls.

The material mixture of the core 3 also contains the thermal conductive filler, which is added to the plastic and distributed as homogeneously as possible in the core 3. The filler is indicated, together with the other functional additives in Figure 1, by the points shown in the core 3, which are indicated only once with the reference symbol 12 for clarity. The filler can be inorganic, especially metals or minerals. For example, the filler can be silver, copper or silicon carbide. Similarly, the filler can include 35 carbon nanotubes. The larger filler molecule has a thermal conductivity λ greater than 35 W/mK. This shows that the fillers have a significantly higher thermal conductivity than the plastic, for example, a thermal conductivity of λ greater than 0.04 K/m2 and a significantly higher thermal conductivity than the steel, which is also produced on a steel sheet.

The material mix of core 3 also contains the functional additives. The additives used here include thermochromic colour pigments which signal to the user by colour change that a defined temperature or a critical temperature range has been reached. The use of thermochromic colour pigments in core 3 of the abrasive carrier 1 is particularly useful when abrasives are used which cover core 3 only in sections. This may be, for example, a cylindrical abrasive casing arranged on the cylindrical section of core 3.

The functional additives can also influence the friction behaviour of an external surface 13 of the core 3 and thus increase the coefficient of adhesion.

Thus, core 3 here consists of 25 to 75% by weight of the filler and 0.5 to 10% by weight of the functional additives, with the remainder of core 3 being plastic, although marginal impurities cannot be excluded.

On the outer surface 13 of core 3 a coating 14 is applied, which contains antibacterial and antifungal agents to provide the most hygienic starting product for the treatment of patients.

A grinding tool of the invention is shown in Figure 2 showing, in addition to the grinding tool carrier 1 shown in Figure 1, an interchangeable grinding tool 15 suspended on the core 3.

The abrasive 15 has a surface 16 enclosed perimeterally around the longitudinal axis X, enclosing a cavity 17 extending along the longitudinal axis X. The abrasive 15 is shown here in the form of a seamless abrasive cap. In the cavity 17 the core 3 of the abrasive carrier 1 described in connection with Figure 1 is included.

The outer surface 13 is complementary to the surface 16 and is shaped as a coating surface enclosed in perimeter around the longitudinal axis X. Thus, the surface 16 of the abrasive 15 is flat on the outer surface 13 of the core 3, so that the interchangeable abrasive 15 is held only by the adhesive force on the core 3.

On one side of the abrasive 15 facing away from the core 3 is a abrasive layer 18 which contains abrasive grains embedded in a binder, in particular resin; in the abrasive layer 18 there are thermochromic colour pigments to determine the outer surface temperature of the abrasive 15 in particular the abrasive layer 18.

During a grinding operation, friction between the grinding medium 15 and the object to be worked generates frictional heat, which is distributed by the heat-conductive fillers into the core 3. The core 3 can divert the absorbed thermal energy to the surroundings via the front side 8 of the core 3 not covered by the grinding medium 15. The metal flange 6 and the metal shaft 2, especially with the heat transfer media 10, support the transport of the thermal energy absorbed in the core 3 to the surroundings.

List of reference marks

1 abrasive carrier2 shaft3 core4 front end5 rear end6 flange7 outer side8 rear end9 sheep section10 heat transfer 11 tension mark12 filler and functional additives13 outer surface14 coating15 abrasive16 surface17 cavity18 abrasive layerEEX plane

Claims (15)

1. Abrasive tool comprising

   an abrasive carrier (1) having a shaft (2) for connecting the abrasive carrier (1) to a drive means for rotatably driving the abrasive carrier (1) about a longitudinal axis (X) and a core (3) connected to an axial end (4) of the shaft (2),

   wherein the core (3) consists of a material mixture comprising a plastic with a thermally conductive filler, wherein the filler has a thermal conductivity greater than 35 watts per metre and per Kelvin, and

   an abrasive means (15),

   characterised in

   that the abrasive means (15) has a surface (16) which is closed in the circumferential direction about the longitudinal axis (X) and which encloses a cavity (17) extending along the longitudinal axis (X),

   wherein the core (3) is received at least in sections in the cavity (17), and

   that the plastic is foamed.
2. Abrasive tool according to claim 1, characterised in that the abrasive means (15) is replaceably arranged on the core (3), wherein the abrasive means (15) adheres to the abrasive carrier (1) by friction between an outer surface (13) of the core (3) and the surface (16) of the abrasive means (15).
3. Abrasive tool according to claim 1 or 2, characterized in that the abrasive means (15) comprises a flexible backing material coated with an abrasive material on an abrasive side facing away from the core (3).
4. Abrasive tool according to any one of claims 1 to 3, characterised in that the abrasive means (15) is an abrasive cap or an abrasive sleeve, wherein the abrasive sleeve encloses the core only in sections.
5. Abrasive tool according to any one of claims 1 to 4, characterized in that the volume of the foamed plastic is 70% to 95% of the total volume of the core (3), the volume of the filler and the volume of at least one optional functional additive together being at most 30% of the total volume of the core (3).
6. Abrasive tool according to any one of claims 1 to 5, characterized in that the core (3) consists of 25 to 75 percent by weight of the filler and 0 to 10 percent by weight of at least one or the functional additive, the remainder of the core (3) consisting of the plastic and unavoidable impurities.
7. Abrasive tool according to claim 6, characterized in that the at least one functional additive is selected from the group comprising thermochromic colour pigments, antibacterial agents, antifungal agents, friction modifying agents.
8. Abrasive tool according to any one of claims 1 to 7, characterized in that the plastic has a bulk density of 700 to 1250 kilograms per cubic metre and/or a Shore A hardness of 30 to 90.
9. Abrasive tool according to any one of claims 1 to 8, characterised in that the plastic is selected from the group comprising polyurethane, elastic polymers, silicone, synthetically produced rubber, natural rubber.
10. Abrasive tool according to any one of claims 1 to 9, characterised in that the shaft (2) is made of a material having a thermal conductivity greater than 35 watts per metre and per Kelvin.
11. Abrasive tool according to any one of claims 1 to 10, characterized in that the shaft (2) comprises heat transfer means (10) provided on the shaft (2) in a shaft portion (9) located outside the core (3).
12. Abrasive tool according to any one of claims 1 to 11, characterized in that at least one radially projecting flange (6) is arranged on the shaft (2), wherein the flange (6) is made of a material having a thermal conductivity greater than 35 watts per metre and per Kelvin.
13. Abrasive tool according to any one of claims 1 to 12, characterized in that the abrasive carrier (1) comprises a coating (14) applied to the outer surface (13) of the core (3), wherein the coating (14) comprises thermochromic colour pigments and/or antibacterial agents and/or an antifungal agent.
14. Abrasive tool according to any one of claims 1 to 13, characterized in that the abrasive means (15) comprises thermochromic colour means for determining an outer surface temperature of an abrasive layer (18) of the abrasive means (15).
15. Use of an abrasive tool according to any one of claims 1 to 14 for treating human body parts.