GRINDING BODY HAVING REDUCED WEIGHT

Abstract

A grinding body including a substantially cylindrical outer member for receiving an abrasive material, an inner member for attaching the grinding body to a drive unit, and a connecting structure for mechanical force transmission between the outer member and the inner member. The outer member, the inner member, and/or the connecting structure may be made at least in part of a fiber-plastic composite.

Description

The present invention relates under various aspects to a grinding body, a usage of a grinding body and a method for making a grinding body.

Various grinding bodies are known from the prior art. Grinding bodies can be used for the machining of various objects. For this, an abrasive material is applied to the grinding body. After the abrasive material becomes worn down, it may be replaced and the grinding body can be used once more. However, the grinding bodies of the prior art have a relatively heavy weight. On the one hand, this results in a high price for the grinding body. On the other hand, the heavy weight makes the handling of the grinding body more difficult.

To remedy this, it is already known from the prior art how to employ a fiber-plastic composite (FKV) for the grinding body. Thus, for example, the Japanese publication JP11028668 A describes a grinding wheel having a core of several platelike coated layers of a fiber-plastic composite. A grinding wheel section is glued onto the core. The core furthermore has flange sections on its side surfaces, by which the core can be secured on a shaft. As a result, this should achieve a low weight, so that a high speed can be accomplished during the grinding.

However, it continues being a problem that even such grinding wheels still have a relatively heavy weight, which furthermore results in a cost-intensive production and a complicated handling.

Based on this prior art, the problem which the invention proposes to solve is therefore to indicate a grinding body, a use of a grinding body and a method for making a grinding body, wherein an economical manufacturing can be achieved with low weight.

According to a first aspect, the problem is solved by a grinding body with a substantially cylindrical outer member for receiving an abrasive material, with an inner member for attaching the grinding body to a drive unit, and with a connecting structure for mechanical force transmission between the outer member and the inner member, wherein the outer member, the inner member and/or the connecting structure are made at least in part of a fiber-plastic composite.

It has been discovered that, thanks to the layout of the grinding body according to the invention consisting of outer member, inner member and connecting structure in combination with the use of fiber-plastic composite materials, a grinding body of reduced weight can be produced. This is due to the fact that the structure according to the invention in combination with the material choice according to the invention can accomplish a structure with extremely streamlined flow of force, optimized in stiffness and in strength, which can serve as a vehicle for the abrasive material. Thus, the rotational mass and with it also the centrifugal forces occurring during the machining process of grinding can be reduced. Furthermore, greater acceleration of the grinding body and improved weight balancing can be achieved.

Thanks to the substantially cylindrical outer member, the abrasive material can be received advantageously. The abrasive material may for example be secured (removably) to the outside of the outer member, especially by being glued to it. Thus, thanks to the substantially cylindrical outer member, a sufficient contact surface for the abrasive material and thus a sufficiently large grinding surface can be provided.

Thanks to the inner member, an attachment to a drive unit can be accomplished, especially via its inner side. The attachment may be direct or indirect. For example, the inner member serves for the attaching to a drive shaft. The inner member in this case is arranged preferably, at least for a portion, preferably entirely, inside the outer member.

In this case, it is possible to economize on material inside the outer member, since no massive grinding body is provided, but instead a connecting structure. The connecting structure serves for the mechanical force transmission, especially the torque transmission from the inner member to the outer member. The connecting structure may be configured in various ways, as long as it enables a mechanical force transmission. The connecting structure preferably extends from the inside of the outer member to the outside of the inner member. Preferably, the connecting structure runs substantially perpendicular to the inside of the outer member and substantially perpendicular to the outside of the inner member.

It has proven to be especially advantageous when both the outer member and the inner member and the connecting structure consist of a fiber-plastic composite. For example, the outer member, the inner member and the connecting structure consist of the same fiber-plastic composite. However, it is likewise possible to employ different fiber-plastic composite materials (such as a different fiber or a different plastic matrix) for the outer member, the inner member and the connecting structure.

According to one exemplary embodiment of the grinding body under the first aspect, the inner member is a substantially cylindrical inner member. With a substantially cylindrical inner member, an advantageous surface for the attaching to a drive unit can be provided via the inside of the inner member. The substantially cylindrical inner member and the substantially cylindrical outer member are preferably arranged concentrically to each other.

The inside of the inner member is preferably conically tapering, looking along its cylinder axis. In this way, a secure connection can be produced for example with a drive shaft.

According to one exemplary embodiment of the grinding body under the first aspect, the fibers of the fiber-plastic composite of the outer member, the inner member and/or the connecting structure are formed as a laid web, woven fabric, braiding, surface structure and/or winding structure. Preferably, the fibers of the fiber-plastic composite of both the outer member, the inner member and the connecting structure are formed as so described. Thanks to the described formations of the fiber-plastic composite and the resulting fiber orientation, the rotational forces which occur, the acting torques, and the stiffness requirements for the grinding body can be advantageously taken into account. As a result, a further reduction in weight of the grinding body can be achieved with good stiffness.

According to one exemplary embodiment of the grinding body under the first aspect, the fibers of the fiber-plastic composite of the outer member and/or the inner member are oriented at least for a portion in the circumferential direction of the respective member. This can advantageously increase the bending and torsional strength of the grinding body. In particular, it has been discovered that a fiber-plastic composite with braided or wound fibers is advantageous in this regard.

According to one exemplary embodiment of the grinding body under the first aspect, the fibers of the fiber-plastic composite of the outer member, the inner member and/or the connecting structure are oriented at least for a portion along the surface of the respective member. Thanks to such a fiber orientation, a further advantageous stability and strength of the grinding body can be achieved, so that the weight of the grinding body can be further reduced.

According to one exemplary embodiment of the grinding body under the first aspect, the fiber-plastic composite of the outer member, the inner member and/or the connecting structure is composed of one or more layers. In particular, a multilayered composition of the respective fiber-plastic composite can accomplish a strain-adapted layer composition of the grinding body, since the rotational forces, the acting torques, and the stiffness requirements can be taken into account in this way, and as a result a grinding body with low weight can be produced.

According to one exemplary embodiment of the grinding body under the first aspect, the connecting structure is formed as a flat, especially a disc-shaped connecting element. A flat, disc-shaped connecting element can be formed for example as a flat disc arranged between the outer member and the inner member, running preferably substantially perpendicular to the cylinder axis of the outer member and the inner member.

The grinding body in this embodiment may advantageously have a cover, in particular. The cover is preferably provided at one end of the grinding body, so that in any case the space between the outer member and the inner member is covered on one side. In this way, an excessive accumulation of grinding dust between outer member and inner member and connecting structure can be prevented.

According to one exemplary embodiment of the grinding body under the first aspect, the connecting structure has a quasi-isotropic layer structure. In this way, uniform properties of the connecting structure can be achieved, especially as regards its stability and elasticity. In particular, a disc-shaped connecting structure can behave like a metal material. As a result, a weight reduction can therefore be accomplished with adequate mechanical properties.

By a quasi-isotropic layer structure is meant, in particular, that the elastic properties are invariant with respect to the rotation about the normal. However, perpendicular to the plane of the layer, different properties may exist. The quasi-isotropic layer structure may be composed basically of a various number of layers (for example, unidirectional ones). Preferably, however, the quasi-isotropic layer structure comprises at least three layers.

According to one exemplary embodiment of the grinding body under the first aspect, the connecting structure comprises several elements in spokelike arrangement. Preferably, the connecting structure consists of the spokelike arranged elements. The spokelike arranged elements may be formed, for example, as struts. For example, the spokelike elements run in the radial direction between inner member and outer member. The particular advantage for such a design is that it prevents an accumulation of grinding dust from the outset, since the dust can escape between the spokelike arranged elements.

According to one exemplary embodiment of the grinding body under the first aspect, the spokelike arranged elements each comprise a core of foam material. In this way, an additional weight reduction can be achieved in the area of the connecting structure.

According to one exemplary embodiment of the grinding body under the first aspect, the outer member, the inner member and/or the connecting structure are composed of preforms. For example, carbon fiber preforms are used. By preforms is meant in particular preforms of fibers which are used to form the corresponding regions of the grinding body. For example, different separate preforms are used for the outer member, the inner member and the connecting structure.

According to one exemplary embodiment of the grinding body under the first aspect, the connecting structure is attached by integral bonding and/or by form fit to the outer member and/or inner member. Preferably, the connecting structure is attached by integral bonding and/or by form fit to both the outer member and the inner member. For example, the connecting structure, the outer member and the inner member are made of separate preforms and joined together by infiltration with plastic.

According to one exemplary embodiment of the grinding body under the first aspect, the fibers of the fiber-plastic composite of the outer member, the inner member and/or the connecting structure comprise inorganic and/or organic reinforcing fibers, especially at least one of carbon fibers, glass fibers, basalt fibers, and aramide fibers. With inorganic fibers such as glass fibers or basalt fibers, a high temperature strength and low costs can be advantageously achieved. With organic fibers, such as aramide fibers or carbon fibers, a high degree of orientation of the fibers can be accomplished in particular.

According to one exemplary embodiment of the grinding body under the first aspect, the matrix material of the fiber-plastic composite of the outer member, the inner member and/or the connecting structure comprises a thermoset or a thermoplastic. For thermosets, the relatively high thermomechanical strength and the low specific gravity are advantageous, while for thermoplastics the possibility of welding is present, for example.

According to one exemplary embodiment of the grinding body under the first aspect, the grinding body comprises a metal bushing arranged at least for a portion inside the inner member. Thanks to the metal bushing, a grinding body can advantageously be provided with a metal hub element. The metal bushing is, for example, substantially cylindrical. For example, the metal bushing is conically tapering, looking in the axial direction. The metal bushing can be connected to the inner member by means of a press fit, which can be accomplished for example by shrink fitting the inner member onto the metal bushing. As a result, thanks to the metal bushing arranged inside the inner member, a grinding body can be provided in hybrid design, enabling a stable attachment to the drive unit, despite having low weight.

According to one exemplary embodiment of the grinding body under the first aspect, the outer member has a larger axial extension than the inner member. By axial extension is meant in the case of a substantially cylindrical outer member or inner member in particular the extension in the direction of the respective cylinder axis. This accomplishes an asymmetrical configuration of the grinding body, enabling an inner member which is shorter than the outer member, without reducing the grinding surface. In this way, a further weight reduction can be achieved, which enables a reduction in the rotational mass and the centrifugal forces during the machining process and a greater acceleration. Furthermore, the drive shaft or tool spindle can be shortened, which decreases the leverage and the acting torques.

According to one exemplary embodiment of the grinding body under the first aspect, the grinding body furthermore comprises an abrasive material applied to the outer member. The abrasive material is designed, for example, as an abrasive coating or as abrasive elements. For example, the abrasive material is applied in an annular fashion to the outside of the outer member, especially by means of a glue layer.

According to a second aspect, the aforementioned problem is solved by a use of a grinding body according to the first aspect for the abrasive machining of metal parts, especially cam shafts. For the abrasive machining and especially the grinding of metal parts, such as cam shafts, large diameters and high speeds of the grinding body are needed. The grinding bodies according to the first aspect are especially suited to this application by virtue of their properties, especially their low weight.

According to a third aspect, the aforementioned problem is solved by a method for making a grinding body, especially according to the first aspect, where the method involves: forming of a substantially cylindrical outer member to receive an abrasive material, forming of an inner member for attaching the grinding body to a drive unit and forming of a connecting structure for the mechanical force transmission between the outer member and the inner member, wherein the outer member, the inner member and/or the connecting structure are formed at least in part of a fiber-plastic composite.

As already noted in regard to the first aspect, the production according to the invention can provide an advantageous construction and as a result a grinding body of reduced weight, since thanks to the structure according to the invention in combination with the choice of materials according to the invention one can achieve a grinding body with extremely streamlined flow of force, optimized in stiffness and in strength. As already noted, the inner member is preferably designed as a substantially cylindrical inner member. The outer member, the inner member and the connecting structure may be formed in succession or also at the same time.

According to one exemplary embodiment of the method under the third aspect, the outer member, the inner member and/or the connecting structure are formed in that first of all fibers are placed onto a mold and then the fibers are infiltrated with plastic. Thanks to the use of a mold, the construction and geometry of the grinding body can be precisely determined, since the fibers can be placed at first as preforms into the desired position and orientation. After this, the fibers can be fixed by the plastic infiltration and consolidation. The plastic infiltration may be done with pressure assistance or vacuum assistance. In particular, individual preforms can be integrally bonded together in this way.

Alternatively or additionally, it is conceivable for the fibers to be placed on the molds already pre-infiltrated, for example, as a prepreg. In this case, the fibers for example are pre-impregnated with a reaction resin. The fibers may then be cured, in particular, under the action of temperature and pressure.

According to one exemplary embodiment of the method under the third aspect, the grinding body after being infiltrated is stripped by being removed from the mold. Thanks to the infiltration, an integrally bonded connection is achieved in particular between the outer member, the connecting structure and the inner member. After the infiltration, the mold which gives the fiber-plastic composite and thus the grinding body its shape can therefore be removed.

According to one exemplary embodiment of the method under the third aspect, the mold comprises separate mold sections for the outer member, the inner member and/or the connecting structure. This enables a simple manufacturing process. The mold sections are in particular separate parts, which can be mounted on one another or joined to one another. For example, one mold section is provided for the inner member, one mold section for the connecting structure and one mold section for the outer member. In this way, the fibers for example as preforms may be placed at first on the corresponding mold sections, for example by being wound around them. After this, the mold sections can be mounted in place. Finally, the fibers may be infiltrated.

According to one exemplary embodiment of the method under the third aspect, a metal bushing is arranged and secured for at least a portion inside the inner member. In this way, a hybrid design can be achieved, enabling a good stability of the grinding body in the area of the attachment to the drive unit. For example, the inner member can be shrunk-fit on the metal bushing by utilizing the geometrical configuration or the different thermal strain behavior of the metal bushing and the inner member. In this way, a press fit of the metal bushing can be achieved.

Regarding further advantageous embodiments of the second and the third aspect, reference is made in particular to the description of the first aspect and the advantages described there. The previous or the following description of embodiments of the different aspects will also disclose in particular advantageous embodiments for the other respective aspects as well.

Further exemplary embodiments of the different aspects of the invention will be found in the following detailed description of exemplary embodiments of the present invention, especially in connection with the figures.

However, the figures included in the application should only serve the purpose of illustration, not for determining of the range of protection of the invention. The enclosed drawings are not drawn true to scale and should merely reflect the general concept of the present invention. In particular, features which are contained in the figures should in no way be considered to be a necessary part of the present invention.

The drawing shows in

FIGS. 1a, b a first exemplary embodiment of a grinding body according to the first aspect in a partial top view and in a partial longitudinal section;

FIGS. 2a, b a second exemplary embodiment of a grinding body according to the first aspect in a partial top view and in a partial longitudinal section;

FIG. 3 a schematic representation of an advantageous fiber orientation; and

FIG. 4a-d a schematic representation of an exemplary embodiment of a method of production according to the third aspect.

FIG. 1 shows first of all a first exemplary embodiment of a grinding body 1 according to the first aspect in partial top view (FIG. 1a) and in partial longitudinal section (FIG. 1b).

The grinding body 1 comprises a substantially cylindrical outer member 2 for receiving an abrasive material (not shown). The abrasive material may be applied, for example, flat against the outside of the outer member 2. Furthermore, the grinding body 1 has a substantially cylindrical inner member 4 for attaching the grinding body 1 to a drive unit (not shown) and a connecting structure 6 for the mechanical force transmission between the outer member 2 and the inner member 4. The outer member 2, the inner member 4 and the connecting structure 6 are all formed from a fiber-plastic composite, the fibers each being organic reinforcing fibers, in this case carbon fibers. Alternatively or additionally, however, other fibers may also be used, such as glass fibers, basalt fibers, or aramide fibers. The plastic or the matrix material of the fiber-plastic composite can be a thermoset or a thermoplastic.

The connecting structure 6 here is formed of several radially outwardly running spokelike arranged struts, of which only two struts 6a, 6b are represented here. This has the advantage that, due to the cutout areas, a depositing of grinding dust on the connecting structure 6 can be reduced. The struts 6a, 6b etc. may have a core of foam material, in order to make possible an especially lightweight variant of the grinding body 1.

The connecting structure 6 here is attached in particular by integral bonding to both the outer member 2 and to the inner member 4. This can be accomplished, in particular, by means of a plastic infiltration.

The outer member 2 and the inner member 4 are concentrically arranged and have a common cylinder axis 8. The outer member 2 and the inner member 4 extend respectively in both directions, starting from the connecting structure 6, substantially parallel to the axis 8. As can be seen, the outer member 2 has a greater axial extension than the inner member 4 on one side, or the inner member 4 has a correspondingly shorter axial extension on one side. Thanks to this asymmetrical configuration, a further weight reduction is accomplished in particular, which makes possible a reduction of the rotational mass and the centrifugal forces during the machining process and thus a higher acceleration.

The fibers of the fiber-plastic composite of the outer member 2, the inner member 4 and the connecting structure 6 are preferably formed as a laid web, woven fabric, braiding, surface structure and/or winding structure. Preferably the fiber-plastic composite of the outer member 2, the inner member 4 and the connecting structure 6 has a multilayer construction. The fibers of the outer member 2, the inner member 4 and the connecting structure 6 are made of preforms.

Inside the inner member 4 there is furthermore arranged a metal bushing 10 as a hub element, by which a shaft and hub connection can be produced. The inner member 4 has been shrunk-fit onto the metal bushing 10, so that the metal bushing 10 is fixed by means of a press fit in the inner member 4. The inner member 4 and/or the metal bushing 10 are/is formed conically tapering, looking along the cylinder axis 8.

FIG. 2 now shows a second exemplary embodiment of a grinding body 1′ according to the first aspect in top view (2a) and in longitudinal section (2b). The second exemplary embodiment is similar to the exemplary embodiment represented in FIG. 1. Accordingly, reference is at first made to the remarks on FIG. 1 and the same reference numbers (with an added stroke) shall be used. The differences shall be discussed below.

In the exemplary embodiment represented in FIG. 2 the connecting structure 6′ of the grinding body 1′ in particular has a different configuration. The connecting structure 6′ in this case is formed as a flat, disc-shaped connecting element 6′. The disc-shaped connecting structure 6′ in this case has a quasi-isotropic layer structure, so that the connecting structure 6′ behaves in the plane in a similar manner to a metallic material.

The grinding body 1′ furthermore has a cover 12′. The cover 12′ is provided at one end of the grinding body 1′, so that the space between the outer member 2′ and the inner member 4′ is covered. In this way, an excessive accumulation of grinding dust between the outer member 2′, the inner member 1′ and the disc-shaped connecting structure 6′ can be prevented.

FIG. 3 shows a schematic representation of one advantageous fiber orientation of a grinding body. The grinding body may be, for example, the grinding body 1 of FIG. 1 or the grinding body 1′ of FIG. 2.

As indicated by the broken lines, the fibers of the fiber-plastic composite of the outer member 2, 2′ and the inner member 4, 4′ are oriented at least for a portion in the circumferential direction of the respective member. The fibers of the fiber-plastic composite of the outer member 2, 2′, the inner member 4, 4′ and the connecting structure 6, 6′ are oriented at least partly along the respective surface.

FIG. 4a-d now show a schematic representation of an exemplary embodiment of a method of production according to the third aspect. In this case, the grinding body 1′ shown in FIG. 2 is being produced. However, the production method shown may also be applied to the production of a different grinding body, such as the grinding body 1.

First of all, fibers 30 are applied as a disc-shaped preform on a mold section 20 in order to form the later connecting structure 6, 6′ (FIG. 4a).

After this, fibers 32 are applied as a preform on a cylindrical mold section 22 in order to form the later inner member 4, 4′ (FIG. 4b). The mold sections 20 and 22 may then be joined together.

Now, the mold sections 20, 22 are connected to a further cylindrical mold section 24. On the mold section, consisting of the mounted molds 20 and 24, the fibers 34 are applied by a braiding process to form the later outer member 2, 2′ (FIG. 4c).

After this, an enclosing outer mold (not shown) is mounted in place, modeling the negative-shaped substantially cylindrical contour of the outer member 2, 2′ being formed. The outer mold and the now inside molds 20, 22, 24 form the mold cavity for the fibers 30, 32, 34. The cylindrical contour may also have changes in diameter in order thus to be able to apply offset or stepped abrasive coatings, without having to machine by cutting (milling/turning) the offset outer contour of the consolidated fiber composite body.

Finally, the fibers 30, 32, 34 are infiltrated with plastic, so that the outer member 2, 2′, the inner member 4, 4′ and the connecting structure 6, 6′ are formed from a fiber-plastic composite. After the infiltration and consolidation, the grinding body 1′ can be stripped by removing the individual mold sections 20, 22, 24 (FIG. 4d).

Claims

1.-23. (canceled)

24. A grinding body comprising: a cylindrical outer member for receiving an abrasive material;an inner member configured to be attached to a drive unit; anda connecting structure for mechanical force transmission between the cylindrical outer member and the inner member, wherein at least one of the outer cylindrical member, the inner member, or the connecting structure comprises a fiber-plastic composite.

25. The grinding body of claim 24 wherein the inner member is cylindrical.

26. The grinding body of claim 24 wherein fibers of the fiber-plastic composite are formed as at least one of a laid web, a woven fabric, braiding, a surface structure, or a winding structure.

27. The grinding body of claim 24 wherein fibers of the fiber-plastic composite of at least one of the cylindrical outer member or the inner member are oriented at least for a portion in a circumferential direction of the at least one of the cylindrical outer member or the inner member.

28. The grinding body of claim 24 wherein fibers of the fiber-plastic composite are oriented at least for a portion along a surface of the at least one of the outer cylindrical member, the inner member, or the connecting structure.

29. The grinding body of claim 24 wherein the fiber-plastic composite is comprised of one or more layers.

30. The grinding body of claim 24 wherein the connecting structure is configured as a flat connecting element.

31. The grinding body of claim 24 wherein the connecting structure has a quasi-isotropic layer structure.

32. The grinding body of claim 24 wherein the connecting structure comprises a plurality of elements disposed in a spokelike arrangement.

33. The grinding body of claim 32 wherein the plurality of elements of the spokelike arrangement each comprise a core of foam material.

34. The grinding body of claim 24 wherein at least one of the cylindrical outer member, the inner member, or the connecting structure is comprised of a preform.

35. The grinding body of claim 24 wherein the connecting structure is attached by at least one of integral bonding or a form fit to the cylindrical outer member or the inner member.

36. The grinding body of claim 24 wherein fibers of the fiber-plastic composite comprise at least one of carbon fibers, glass fibers, basalt fibers, or aramide fibers.

37. The grinding body of claim 24 wherein matrix material of the fiber-plastic composite comprises a thermoset or a thermoplastic.

38. The grinding body of claim 24 comprising a metal bushing disposed at least partially inside the inner member.

39. The grinding body of claim 24 wherein the cylindrical outer member has a larger axial extension than the inner member.

40. The grinding body of claim 24 wherein the abrasive material is applied to the cylindrical outer member.

41. A method for making a grinding body comprising: forming a cylindrical outer member to receive an abrasive material;forming an inner member for attaching the grinding body to a drive unit; andforming a connecting structure for the mechanical force transmission between the cylindrical outer member and the inner member,wherein at least one of the cylindrical outer member, the inner member, or the connecting structure is comprised at least in part of a fiber-plastic composite.

42. The method of claim 41 comprising forming at least one of the cylindrical outer member, the inner member, or the connecting structure by placing fibers on a mold and then infiltrating the fibers with plastic.

43. The method of claim 42 comprising stripping the grinding body by removing the at least one of the cylindrical outer member, the inner member, or the connecting structure from the mold after the infiltration with plastic.

44. The method of claim 42 wherein the mold comprises separate mold sections for the cylindrical outer member, the inner member, and the connecting structure.

45. The method of claim 41 comprising positioning and securing a metal bushing at least partially inside the inner member.