Patent Application
20220134511
The present invention concerns an abrasive segment for a grinding roller including at least one carrier body for positively lockingly fixing the abrasive segment to a peripheral surface of the grinding roller and at least one substantially flat abrasive layer. The present invention further concerns a grinding roller for machining a surface of a workpiece and/or a surface of a negative form for the production of the workpiece, wherein the grinding roller has a substantially cylindrical main body having a peripheral surface. The present invention further concerns a grinding machine having at least one grinding roller according to the invention including abrasive segments according to the invention and at least one rotary drive. The present invention moreover concerns a use of such an abrasive segment, such a grinding roller or such a grinding machine.
Such an abrasive segment is already known from the specification of DE 20 2005 016 671 U1 in which the abrasive is fixed on a support means with a hook and loop fastener strip in such a way that the abrasive layer is oriented in normal relationship with the peripheral surface of the grinding roller and upon contact of the abrasive segment with a workpiece the abrasive segment is elastically deformed in one direction.
A disadvantage with the state of the art in accordance with a first aspect is that the orientation of the abrasive layer in normal relationship with the peripheral surface of the grinding roller means that during rotation in the grinding process the removal rate is only limitedly effective as the force on the workpiece cannot be transmitted to the workpiece in the optimum fashion by elastic deformation of the abrasive segment.
Furthermore during the removal process the abrasive segment follows the contour and therefore does not substantially contribute to flattening of a surface of the workpiece.
The abrasive segment described in DE 20 2005 016 671 U1 is provided with an elastically deformable support means, in which respect this preferably involves an elastically bendable material like a brush, a foam or some other suitable material.
A disadvantage with the state of the art in accordance with a second aspect is that the elastically bendable materials are adapted to the deformation during the grinding process but are not designed for a grinding fluid feed and/or grinding fluid storage.
In addition, by virtue of the described support means it is only very limitedly possible to cater for relevant properties in the removal process like vibration damping, acoustic insulation, thermal protection, varying surface geometries and so forth.
Such a grinding roller is known from the specification of DE 20 2005 016 671 U1 that has mounted abrasive segments that are provided with an abrasive layer, being oriented in normal relationship to the peripheral surface.
A disadvantage with the state of the art is that material can be removed only in one direction of rotation without conversion of the fixed abrasive segments.
A grinding machine having abrasive segments is known from the specification of DE 20 2005 016 671 U1, in which the abrasive segments are arranged in the grinding roller in such a way that the abrasive layer is oriented in normal relationship to the peripheral surface of the grinding roller and thereby after fitment of the grinding roller the direction of rotation of the grinding roller is determined by the function of the abrasive layer.
A disadvantage there is that the orientation of the abrasive layer in normal relationship to the peripheral surface of the grinding roller means that during rotation in the grinding process, by virtue of the abrasive layer being oriented in normal relationship to the peripheral surface of the grinding roller, it is also not possible to generate in the direction of rotation that is solely possible for the grinding process an automatic advance which is preferably necessary for large workpieces with manual machining and in addition this does not permit a high removal rate.
The technical object according to the first aspect of the present invention is therefore to provide an abrasive segment which is improved over the state of the art and in which the disadvantages of the state of the art are at least partially overcome and which is distinguished in particular by an abrasive layer which permits an increased material removal and the material removal by the abrasive segment also contributes to significant flattening of the workpiece surface.
The technical object of the second aspect is to provide an abrasive segment which ensures an effective grinding fluid feed and grinding fluid storage and which is matched to parameters relevant for the removal process like vibration, sound, heat, surface shape and so forth, wherein it is not necessary to dispense with convenient handling and/or a long service life and the grinding result is improved.
A further object according to a third aspect of the present invention is to provide a grinding roller which is improved over the state of the art and in which the disadvantages of the state of the art are at least partially overcome and which is distinguished in particular in that the grinding roller can be used in both directions of rotation that are relevant for the removal process.
A further object according to a fourth aspect of the present invention is to provide a grinding machine which is improved over the state of the art and in which the disadvantages of the state of the art are at least partially overcome and which is distinguished both by user-friendly handling in relation to large grinding rollers (from a roller length and/or a roller diameter of around 300 mm) and also by a high level of possible removal on the workpiece.
A further object according to a fifth aspect of the present invention is to provide a use of the abrasive segment, the grinding roller or the grinding machine, that is improved over the state of the art.
Accordingly, the at least one abrasive layer in a state of the abrasive segment of being fixed to the grinding roller is oriented substantially parallel to the peripheral surface of the grinding roller and at least one elastic intermediate layer is arranged between the at least one carrier body and the at least one abrasive layer.
By virtue thereof, it is possible for the first time for the contact and thus also the transmission of force between the abrasive layer and the workpiece surface to be effected substantially normal to the peripheral surface of the grinding roller, wherein an increased removal rate on the workpiece (for example a negative form and the form parts thereof) is guaranteed as the abrasive segment can apply more pressure to the surface.
Furthermore, the parallel orientation of the abrasive layer with respect to the peripheral surface ensures efficient leveling of the surface to be machined, wherein in particular residues are effectively dealt with and the surface is locally corrected to the factors in the surrounding area and flattened.
In particular, after repair operations in negative forms by virtue of compensating materials unevenness and residues remain to an increased extent, and they can be effectively removed by that abrasive segment.
The term elastic (synonymous with compressible while retaining shape) means that the intermediate layer is compressible under the influence of a force and when a force is no longer applied the intermediate layer returns to its original shape again. That property achieves substantially two advantages, namely that the layer has a pressure-compensating effect and it deploys a damping action in the grinding process.
It is accordingly provided that arranged between the at least one carrier body and the at least one abrasive layer is at least one elastic intermediate layer which substantially comprises felt.
That makes it possible for the first time that, by virtue of the sponge-like nature, a structure in respect of the elastic intermediate layer can be afforded, which is suitable both for receiving and storing fluid and also delivering fluid in the optimum fashion for the removal process.
The elastic intermediate layer which substantially comprises felt means that the abrasive segment can be operated both in a dry grinding procedure and also using grinding fluid.
In addition, the elastic properties of felt have a high compression elasticity and resilience whereby creases and wrinkles scarcely occur, which would be detrimental for the grinding process.
In addition, felt is sound-insulating and provides efficient insulation in respect of heat, wherein those properties, in particular in use of the abrasive segment, provide both for more convenience in operation and also afford a better grinding result. In addition, the cushioning afforded ensures protection from an excessively high mechanical loading on all the components involved like the abrasive layer, carrier body and/or workpiece.
Adaptation of the properties of the felt to the individual requirement of the surface to be machined can also be controlled by way of the density of the basic felt layer.
Added to that there is the positive property that even regions which are curved to differing degrees and/or regions of differing thickness can be simultaneously machined by virtue of the material-specific properties of felt without having in advance to influence the form of the curved regions and/or regions of differing thickness in regard to the configuration of the abrasive segment and without having to suffer a loss in removal rate. As a result the removal procedure also acts in particular in producing leveling of the surface.
Furthermore, the abrasive segment with the elastic intermediate layer comprising felt affords the option of additionally dealing with special and challenging curved regions like for example convex or concave geometries without major cost or resources involvement insofar as the elastic intermediate layer of felt follows the curvature of the workpiece to be machined. The thickness of the elastic intermediate layer of felt can additionally vary in a thickness over at least a length of the abrasive segment.
The use of felt as the supporting elastic intermediate layer therefore affords the advantage that both the necessary pressure for effective removal of material is transmitted from the carrier element to the workpiece by way of the abrasive layer and also it is possible to pursue complex surfaces in contour.
The vibration-insulating property of felt which can be adapted to the factors involved in the removal process by means of the specific composition permits user-friendly and convenient operation of the abrasive segment which due to the low specific density does not involve any substantial additional weight in terms of handling.
Added to this, there is the positive property that the abrasive segment is exposed to less elastic deformation, and that results in an increase in service life or minimization of the wear phenomena. It is thus possible to dispense with frequently changing the felt layer and also the carrier body.
Accordingly, at least one such abrasive segment is positively lockingly fixed to the peripheral surface.
By virtue of that, it is possible for the first time that the material-specific properties, that are conducive to the grinding process, of the elastic intermediate layer which is formed in particular from felt and can therefore ensure damping, sound insulation, pressure equalization, heat protection, fluid reception/storage/delivery and deformability can be utilized to the optimum extent in both directions of rotation.
Accordingly, the at least one grinding roller can be set in rotation with the at least one rotary drive in order to cause a relative movement of the at least one abrasive layer relative to the surface of the workpiece to be machined and/or the negative form.
As a result, it is possible for the first time that the abrasive layer is oriented substantially parallel to the peripheral surface of the grinding roller and both directions of rotation are provided with an automatic advance during the grinding process. That permits simple operation of grinding rollers with a length extent of up to 800 mm.
The abrasive segments moreover, due to the elastic intermediate layer, ensure large-area contact and effective removal by the abrasive layer over the entire longitudinal extent of the grinding roller.
According to an advantageous configuration of the invention, the at least one elastic intermediate layer is such that a grinding fluid, in particular water, can be stored and delivered therein, and/or is of an abrasive-free configuration.
That provides a particularly advantageous cooperation of the initially abrasive-free workpiece surface and the abrasive layer in a wet grinding process, more specifically such that a grinding fluid stored in the elastic intermediate layer can issue during the removal process and grinding dust which is formed when grinding on the abrasive layer can be efficiently flushed away.
In addition, the abrasive prevents increased heat generation and thus carefully treats both the abrasive layer and also the surface of the workpiece and/or the negative form.
In the case of workpieces and/or negative forms in which no grinding fluid is required in the removal process, it is possible to eliminate additional cleaning operations for the user of the abrasive segment by virtue of the abrasive-free elastic intermediate layer.
Advantageously, the at least one carrier body is substantially T-shaped in cross-section and/or is of such a configuration that the carrier body can be positively lockingly fixed to the peripheral surface of the grinding roller by way of a dovetail connection.
That permits a positively locking connection of the segment to a corresponding groove on a roller, in which the forces acting during the removal process are transmitted to a high degree to the more massive main body of the grinding roller by way of the carrier body.
The use of a dovetail connection affords the positively locking connection to a higher degree as fixing is effected not only in a direction transversely to the dovetail connection but also in a perpendicular direction relative to the groove.
Preferably, in the longitudinal direction of the groove, the abrasive segment is fixed on the grinding roller by a constructive termination.
It has proven to be advantageous if the at least one carrier body includes at least one contact surface at which the at least one elastic intermediate layer is at least region-wise supported, preferably wherein the at least one contact surface is oriented substantially parallel to the at least one flat abrasive layer.
As the parallel orientation both of the abrasive layer and also the carrier body on the peripheral surface of the grinding roller is guaranteed by that arrangement the forces which are required for the removal process and occur during the removal process act to a high degree in the radial direction of the grinding roller. That is advantageous for an effective and careful removal process.
According to an advantageous embodiment of the invention, the at least one elastic intermediate layer is fixed with an adhesive layer to the at least one carrier body and/or to the at least one abrasive layer.
The adhesive layer as a bonding agent is on the one hand cost-effective and is adequate in function for demanding removal processes.
After the end of the service life of the carrier body, the elastic intermediate layer or the abrasive layer the worn parts can be quickly changed by the adhesive layer without requiring a large amount of material.
It has proven to be advantageous if the at least one elastic intermediate layer is of a thickness, the thickness being at least three times as great as a layer thickness of the at least one abrasive layer.
Particularly preferably, the abrasive layer is of a layer thickness in the range of between 0.6 mm and 1.5 mm.
Preferably, the elastic intermediate layer has a thickness in the range of between 5 mm and 12 mm, particularly preferably in the range between 8 mm and 10 mm.
That prevents contact occurring between the carrier bodies and the surface of the workpiece or the negative form when there are more severe surface unevennesses of the workpiece or the negative form.
In addition, the elastic intermediate layer deploys the full extent of its positive material-specific aspects for the removal process, only as from a certain thickness.
An advantageous variant for the machining of surfaces of a workpiece or a negative form comprising composite material provides that the at least one abrasive layer includes at least one abrasive, preferably diamond, cubic boron nitride, sintered corundum and/or an abrasive with zirconium corundum, aluminum oxide and/or silicon carbide, preferably wherein the at least one abrasive is of an abrasive grain size between 50 μm and 745 μm and/or is embedded in at least one bonding agent, preferably a resin bonding agent, preferably wherein the abrasive layer is arranged on a carrier layer.
It is particularly preferred if the peripheral surface is provided with at least one groove for receiving at least one abrasive segment, preferably wherein the at least one groove is of a substantially dovetail-shaped configuration and the at least one abrasive segment is positively lockingly fixed therein.
In an embodiment, the at least one groove is arranged inclinedly relative to a longitudinal direction of the grinding roller, preferably at an angle between 1° and 10°, particularly preferably at an angle between 2° and 3.5°.
That ensures a particularly harmonic grinding process as both upon a first contact of the grinding roller with the workpiece and also during the grinding process preferential transmission of force of the at least one abrasive segment to the workpiece is effected and lower impact forces are generated.
In addition, the angle of the at least one groove makes it possible that in a final phase of the grinding contact of a first abrasive segment a subsequent abrasive segment already comes into contact with the workpiece and that thereby affords a reduction in the times in which the workpiece is not in contact with the at least one grinding segment.
Therefore, the grinding result is improved by an inclined positioning of the at least one groove relative to the longitudinal direction of the grinding roller and the abrasive segments therein.
As the carrier bodies of the abrasive segments are of a substantially T-shaped configuration the at least one corresponding groove affords a force-locking connection for the abrasive segments at the peripheral surface of the grinding roller. A dovetail-shaped connection in that respect affords a secure and force-locking connection of the abrasive segment to the grinding roller in particular under high levels of stress in the removal process.
An embodiment of the invention provides that arranged at at least one end of the substantially cylindrical main body is at least one preferably substantially cylindrical opening for at least one tool receiving means, preferably wherein precisely two openings are arranged at the at least one end.
That achieves the effect that the grinding roller can be used as a tool for the most widely varying grinding machines or grinding robots.
This further permits a rapid change of grinding roller, grinding machine or grinding robot.
That is a relevant factor, in particular for reasons of time and cost, in the machining of large surfaces of the workpieces and/or negative forms.
Arranging the openings at the end makes it possible for the abrasive segments to be able to extend over the full lateral extent of the grinding roller.
If precisely two openings are arranged at the end, that takes account of commercially usual tool receiving means.
In addition, the force arm between the opening and the center point of the end makes it possible for tangentially acting forces in the removal process, caused by the rotation of the grinding roller and the relative movement between the abrasive segment and the surface, to be transmitted by way of the tool receiving means to the grinding machine or grinding robot and compensated, to a higher degree.
According to a preferred embodiment of the invention, at least one locking mechanism, at least one cover, and at least one opening are provided. The opening is arranged in the at least one cover, and the at least one locking mechanism can be introduced into the at least one opening, for arresting the at least one abrasive segment are arranged at at least one of the ends of the substantially cylindrical main body.
That ensures a more effective positively locking and force-locking relationship between the abrasive segment and the grinding roller.
In addition, the arrangement at the end of the main body means that the arresting effect can already be effected in a user-friendly fashion after fitment has been effected to a grinding roller or a grinding robot.
Alternatively, it is possible to provide at least one handle, preferably having at least one grinding fluid feed means, for manual guidance of the grinding machine.
The handle ensures convenient handling even for large heavy grinding rollers.
The abrasive layer is supplied with grinding fluid by means of the grinding fluid feed means, without a grinding fluid feed that has to be externally operated. That saves on unnecessary working steps in the removal process and also affords more convenient handling with the grinding machine or the grinding robot.
Further preferably, there is at least one robot arm, arranged at the end of which is at least one tool receiving means of at least one grinding roller, preferably wherein the tool receiving means is provided with at least one grinding fluid feed means.
That makes it possible for the grinding roller to be used even on surfaces which are difficult to access of the workpiece or the negative form while in addition the abrasive layer is supplied with grinding fluid.
According to the invention there is provided the use of an above-described abrasive segment and/or an above-described grinding roller for machining a surface of a workpiece, that is preferably provided with a coating for protection from environmental influences, wherein it is preferably provided that at least one region of the workpiece, that adjoins the surface to be machined, comprises a carbon fiber and/or glass fiber composite material or a surface that is preferably coated with wax of a negative form for the production of a workpiece which preferably at least region-wise comprises a carbon fiber and/or glass fiber composite material.
The uses referred to are effected in a particularly advantageous form for application to the workpiece which is in the form of an airfoil or fuselage of an aircraft, parts of ship, parts of a train or in the form of a rotor blade of a wind turbine.
The uses referred to are effected in a further particularly advantageous form with the feed of a grinding fluid, preferably water, particularly preferably water mixed with soap.
Further details and advantages of the present invention are described more fully hereinafter by means of the specific description with reference to the embodiments by way of example illustrated in the drawings in which:
The carrier body 3 is T-shaped, wherein the T-shape includes a dovetail-shaped limb intended for a dovetail connection (see
The elastic intermediate layer 7 is of a cuboidal configuration. It can however also differ from that shape and/or can be adapted to specific surface geometries to be treated. By way of example the elastic intermediate layer 7 can be of a trapezoidal configuration.
The abrasive layer 6 is of a thickness 16, wherein the abrasive layer 6 includes an abrasive 17, preferably diamond 18, cubic boron nitride 19, sintered corundum 52 and/or an abrasive 17 with zirconium corundum 20, aluminum oxide 21 and/or silicon carbide 22.
The precise composition of the abrasive 17 and the abrasive grain size 18 however can be any desired composition. Particularly preferably the one abrasive 17 is of an abrasive grain size 18 of between 50 μm and 745 μm. The abrasive 17 is held together by a bonding agent 23. Particularly preferably the abrasive 17 is embedded in a resin bonding agent 24 but can also be embedded in another material as the bonding agent 23.
The abrasive layer 6 is arranged on a carrier layer 49. The carrier layer 49 can in itself be of any desired material and is also not absolutely necessary. The abrasive layer 6 can also be applied directly to the elastic intermediate layer 7. A carrier layer 49 of textile is however particularly preferred.
The elastic intermediate layer 7 is fixed with an adhesive layer 14 to the carrier body 3 and/or to the abrasive layer 6. The adhesive layer 14 in that case can be applied over the entire surface area or only region-wise.
The elastic intermediate layer 7 is of a thickness 15, the thickness 15 being a multiple larger than a layer thickness 16 of the abrasive layer 6. Particularly preferably the thickness 15 is at least three times the layer thickness of the abrasive layer 6.
The abrasive layer 6 is applied to the carrier layer 49. The abrasive layer 6 can be applied to the carrier layer 49 over the entire surface area or only region-wise.
The carrier body 3 includes a contact surface 13 at which the elastic intermediate layer 7 is at least region-wise supported. The contact surface 13 is oriented parallel to the flat abrasive layer 6.
The elastic intermediate layer 7 is of such a configuration that a grinding fluid, in particular water 10, can be stored therein and can be delivered, and/or it is of an abrasive-free nature.
The elastic intermediate layer 7, the contact surface 13 and the abrasive layer 6 are oriented substantially parallel and are at an angle of substantially 90° relative to a radial direction of a grinding roller 2 (not shown for the sake of clarity).
The grinding fluid 9 can be of any desired composition. Particularly preferably a water 10 mixed with soap 48 is present in the grinding fluid 9.
The grinding fluid 9 is stored in the fibers 50 of the felt 8 and penetrates between the fibers 50 of the felt 8 upon delivery of the grinding fluid 9 to the abrasive layer 6.
In general the elastic intermediate layer 7 can also be in the form of foams or plastics. In that case the thicknesses of the individual components of the abrasive segment 1 can be different.
The peripheral surface 5 is provided with grooves 29 for receiving abrasive segments 1. In this design the grooves 29 are of a dovetail-shaped configuration. The abrasive segments 1 are positively lockingly fixed in the grooves 29.
A cover 53 is arranged at an end 30 of the cylindrical main body 28 and has two openings 54. Two locking mechanisms 33 engage into those two openings in order to fix the plurality of abrasive segments 1 in an axial direction.
Two cylindrical openings 31 for a tool receiving means 32 are arranged at an end 30 of the cylindrical main body 28. The cylindrical openings 31 can be arranged at one or at both ends 30 of the grinding roller 2.
The cylindrical openings 31 in themselves can be present in any desired number. A particularly preferred embodiment is that in which the end 30 includes two eccentric cylindrical openings 31.
A locking mechanism 33 is arranged at one of the ends 30 of the cylindrical main body 28 for arresting the abrasive segments 1.
The abrasive segments 1 are arranged radially outwardly on the peripheral surface 5. The abrasive segments can be spaced at any desired spacing as indicated at 51. An equidistant arrangement of the abrasive segments 1 is particularly preferred. The spacing 51 between the abrasive segments 1 should not be selected to be so large that the result of the removal process is adversely affected.
The grinding roller 2 can be of a roller diameter in the range of between 80 mm and 400 mm. The grinding roller 2 can be of a roller length in the range of between 50 mm and 800 mm.
There is a handle 35b for manual guidance of the grinding machine 34. The handle 35b is provided with a grinding fluid feed means 36b , wherein the grinding fluid feed means 36b is fixed on and/or in the handle 35b in such a way that the operator is not impeded in handling the grinding machine 34.
The handle 35b can be designed for one-arm or two-arm operation.
The tool receiving means 32 is provided with a grinding fluid feed means 36b . In a further embodiment however that can also be mounted to the robot arm 37 or another component of the grinding machine 34. If no grinding fluid feed means 36b is needed for the removal process it can also be entirely eliminated.
The grinding fluid 9 is passed further to the grinding roller 2 by way of the grinding fluid feed means 36b.
The workpiece 26 can in itself be of any nature. Use of the abrasive segments 1, grinding roller 2 or the grinding machine 3 for the abrasive procedure on airfoils or fuselages 44 of an aircraft, rotor blades 45 of a wind turbine, parts of a ship or parts of a train is however particularly preferred. The workpiece 26 however can also be formed from other extensive geometries 46 comprising composite materials 47.
A region 40 of the workpiece 26, that adjoins the surface 25 to be machined, at least partially comprises a carbon fiber composite material 41 and/or a glass fiber composite material 42.
The use is effected with the feed of a grinding fluid 9. It is optionally also possible however to dispense with the feed of the grinding fluid 9.
The grooves 29 in which the abrasive segments 1 are fixed in positively locking relationship are at an angle in the range of between 1° and 10°, particularly preferably between 2° and 3.5°, relative to a longitudinal direction of the grinding roller 2, but can also be arranged parallel to the longitudinal direction of the grinding roller 2.
The longitudinal direction of the grinding roller 2 is defined by the axial direction (axis of rotation) of the grinding roller 2 and is thus normal to the direction of rotation or a radial direction of the grinding roller 2.
Two locking mechanisms 33 can be seen at the end 30 at the left. The grooves 29 are continuous as far as that facing side and terminate before an opposite side in order to permit a positively locking connection of the abrasive segments 1 (not shown for the sake of clarity) in the grinding roller 2 by a termination of the grooves 29.
In order to fix the abrasive segments 1 to the grinding roller 2 the cover 53 over the openings 54 is released by the locking mechanism 33 (for example by rotation). That removal has already occurred in
Then the abrasive segments 1 are introduced into the grooves 29 as far as the end thereof in order subsequently to again fix the cover 53 on the grinding roller 2 and to secure the abrasive segments 1 in the longitudinal direction.
It is however also possible in accordance with the invention to use two covers 53 for fixing the abrasive segments 1 and to dispense with the termination configuration of the grooves 29.
| Number | Date | Country | Kind |
|---|---|---|---|
| A 50642/2019 | Jul 2019 | AT | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/AT2020/060266 | Jul 2020 | US |
| Child | 17574112 | US |
