GRINDING TOOL AND METHOD OF MANUFACTURING A GRINDING TOOL

Abstract

A grinding tool drivable in rotation about an axis of rotation, including: an abrasive band which is wound spirally with a plurality of superimposed layers about the axis of rotation and has a grinding layer on a band side facing away from the axis of rotation, characterized in that the wound abrasive band is, viewed in a longitudinal section along the axis of rotation, convexly curved with respect to the axis of rotation and the layers of the abrasive band reach radially into one another. Furthermore, the disclosure relates to a method for manufacturing a grinding tool.

Claims

1. A grinding tool drivable in rotation about an axis of rotation, comprising: an abrasive band which is wound spirally with a plurality of superimposed layers about the axis of rotation and has a grinding layer on a band side facing away from the axis of rotation, characterized in that the wound-up abrasive band is, viewed in a longitudinal section along the axis of rotation, convexly curved with respect to the axis of rotation and the layers of the abrasive band reach radially into one another.

2. The grinding tool according to claim 1, wherein, with respect to the axis of rotation, radially inner layer of the abrasive band is axially covered partially by an adjacent radially outer layer of the abrasive band.

3. The grinding tool according to claim 1, wherein the profile geometry of the wound-up abrasive band has a U-shape and/or a V-shape at least partially along the band length of the abrasive band.

4. The grinding tool according to claim 1, wherein the grinding tool has a first main tool side and a second main tool side facing away from the first main tool side, the abrasive band being arranged axially between the first main tool side and the second main tool side with respect to the axis of rotation.

5. The grinding tool according to claim 4, wherein the grinding tool is covered on its first main tool side and/or the second main tool side at least partially by a respective stabilizing layer, the abrasive band being fastened to the at least one stabilizing layer.

6. The grinding tool according to claim 5, wherein the at least one stabilizing layer comprises a binder, wherein in an edge region of the abrasive band facing the respective stabilizing layer the binder extends into intermediate spaces formed between the layers of the abrasive band.

7. The grinding tool according to claim 1, wherein the layers of the abrasive band lie one above the other in an unconnected manner at least in a central grinding region, the central grinding region extending over at least 60 percent of the axial extent of the abrasive band with respect to the axis of rotation.

8. The grinding tool according to claim 1, wherein the grinding tool is a grinding disk and comprises a central supporting body, the abrasive band being arranged around the supporting body.

9. The grinding tool according to claim 8, wherein the abrasive band is fixed to the supporting body by means of the at least one stabilizing layer.

10. The grinding tool according to claim 8, wherein the supporting body is plate-shaped and has a first main body side and a second main body side facing away from the first main body side, as well as an outer circumferential edge, the abrasive band being arranged around the outer circumferential edge.

11. The grinding tool according to claim 10, wherein a first end of the abrasive band terminates at the outer periphery of the grinding tool and a second end of the abrasive band terminates at the outer circumferential edge of the supporting body.

12. The grinding tool according to claim 1, wherein the grinding tool has a multilayer winding with the abrasive band and at least one further abrasive band, the abrasive band and the at least one further abrasive band being wound, at least partially, in multiple layers one on top of the other and spirally with multiple layers one on top of the other about the axis of rotation.

13. A method of manufacturing the grinding tool according to claim 1, comprising the steps of: Providing a primary material in the form of a band-shaped abrasive, Spiral winding of the primary material around the axis of rotation; Arranging the wound primary material in a mold having a cylindrical wall whose inner diameter at least approximately corresponds to the outer diameter of the grinding tool to be produced, and Pressing the wound primary material in a direction along the axis of rotation until the primary material buckles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Preferred embodiments are illustrated in the drawings and described below. Wherein

[0051] FIG. 1 shows a grinding tool according to a first embodiment in longitudinal sectional view along the line I-I shown in FIG. 3;

[0052] FIG. 2 shows a perspective view of the grinding tool from FIG. 1;

[0053] FIG. 3 shows a top view of the grinding tool from FIG. 1;

[0054] FIG. 4 shows a plan view of a label for the grinding tool;

[0055] FIG. 5 shows a plan view of a first reinforcing interlining for the manufacture of the grinding tool;

[0056] FIG. 6 shows a plan view of a wound primary material for the manufacture of the grinding tool;

[0057] FIG. 7 shows a top view of a circular blank for manufacturing of the grinding tool;

[0058] FIG. 8 shows a plan view of a second reinforcing interlining for the manufacture of the grinding tool;

[0059] FIG. 9 shows a plan view of a bore ring for the manufacture of the grinding tool;

[0060] FIG. 10 shows a partial representation of the grinding tool of FIG. 1 in enlarged longitudinal sectional view along the line X-X shown in FIG. 3;

[0061] FIG. 11 shows a cross-sectional view of a grinding tool according to a second embodiment;

[0062] FIG. 12 shows a cross-sectional view of a grinding tool according to a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0063] FIGS. 1 to 10 show a first embodiment of a grinding tool 1 and are described together below. The grinding tool 1 is designed as a grinding disk and can be driven to rotate about an axis of rotation R. The grinding tool 1 has a first main tool side 2 and a second main tool side 3 facing away from the first main tool side, as well as a circumferential side 4. Furthermore, the grinding tool 1 has a central support section 39 arranged concentrically around the axis of rotation R and a grinding section 6 arranged radially outside the support section 39.

[0064] The support section 39 has a first main body side 7 and a second main body side 8 facing away from the first main body side 7. The support section 39 comprises a supporting body 5, which is formed in the shape of a plate, in particular by pressing. The supporting body 5 is made, here merely by way of example, from two resin-impregnated circular blanks 10, 11, one above the other, which are pressed together. The two circular blanks 10, 11 are shown in FIG. 7 and may be fabric circular blanks. In the center, the supporting section 39 may have a recess formed concentrically with respect to the axis of rotation R and having a central bore, in which for instance a bore ring 12 for receiving a tool spindle of a rotary drive machine (not shown), for example a hand-held angle grinder, is inserted. In the assembled state, the grinding tool 1 is placed on the tool spindle in a manner known per se and fastened to the rotary drive machine by means of a spindle nut. The spindle nut is then supported on the first main body side 7 of the support section 39, and may be received within said recess to prevent unwanted contact with the workpiece being machined.

[0065] The grinding section 6 has an abrasive band 13 arranged as a winding around an outer circumferential edge 9 of the supporting body 5. The abrasive band 13 is wound in a spiral around the axis of rotation R with several, here exemplary eighteen, superimposed layers L1, L2, . . . L18. This results in a single-layer winding. In principle, however, it is also possible for the winding to be multi-layered with several such abrasive bands 13. The abrasive band 13 is flexible and may be an abrasive on a backing 14. As shown in FIG. 10, the abrasive band 13 has a grinding layer 16 on a first band side 15, which can also be referred to as the front side, facing away from the axis of rotation R. The grinding layer 16 covers the entire surface of the front side 15 of the abrasive band 13. The grinding layer 16 has abrasive grains 18 embedded in a binder matrix 17 and held on the backing 14. On the other hand, no further grinding layer is applied to the abrasive band 13 on a second band side 19, which can also be referred to as the rear side, facing away from the first band side 15.

[0066] The abrasive band 13 is profiled in longitudinal section along the axis of rotation R and has a profile geometry that is open towards the axis of rotation R. The layers L1 . . . L18 of the abrasive band 13 are arranged reaching radially into one another, wherein a respective radially inner layer L2 . . . L18 of the abrasive band 13 is axially overlapped at least partially by an adjacent radially outer layer L1 . . . L17 of the abrasive band 13. In FIGS. 1 and 10, it can be seen that the profile geometry can have at least partially a U-shape and a V-shape viewed in a longitudinal section. Here, the first, radially outermost layer L1 has a U-shaped profile geometry and the radially inner layers L2, L3, . . . L18 have a V-shaped profile geometry.

[0067] Due to the, here, U-shaped profile geometry of the first layer L1 of the abrasive band 13, the circumferential side 4 of the grinding tool 1 is curved radially outward. The camber is maximum in a central grinding region 20 of the grinding tool 1. The precurved central grinding region 20 lies, due to the spiral winding at least substantially, on a circumferential circle with a diameter defining the outer diameter D1 of the grinding tool 1. The outer diameter D1 is larger than a maximum axial extension B1 of the grinding tool 1, which the grinding tool 1 occupies in the grinding section 6. The ratio between the axial extension B1 and the outer diameter D1 of the grinding tool 1 is preferably less than 1 to 1 and is, here merely by way of example, about 1 to 10. The supporting body 5 has an axial extension B5 that is smaller than the axial extension B1 in the grinding section 6. The supporting body 5 is thus axially offset relative to the grinding section 6, whereby the transition between the grinding section 6 and the supporting body 5 can be stepped. The grinding tool 1 is thus particularly suitable for machining weld seams and fillet welds as well as joints.

[0068] At the beginning of a grinding process, the band section of the grinding layer 16 extending over the first layer L1 is exposed in the circumferential side 4 of the grinding tool 1. The further radially inner layers L2 . . . L18 are then still completely covered by the first layer L1. In FIG. 1, for the sake of clarity, only a subset of the, in this case, nineteen layers are marked with reference signs. In use, the grinding tool 1 is usually placed with the central grinding region 20 against the working surface of the workpiece to be machined. Thus, the layer L1 around the central grinding region 20 wears out first. As soon as this is worn in the central grinding region 20, the band section of the grinding layer 16 extending over the layer L2 behind it is already exposed in the central grinding region 20. Then the two outermost layers L1, L2 participate simulta-neously in the grinding process with grinding effect. In the course of the grinding process, the circumferential side 4 of the grinding tool 1 loses its initially radially outwardly curved profile and subsequently approaches a flat profile extending substantially parallel to the axis of rotation R and continuously shifting toward the axis of rotation R. The individual layers L of the abrasive band 13 wear out continuously from radially outside to radially inside, as a result of which the outside diameter of the grinding tool 1 becomes smaller and smaller. FIG. 10 shows that the interleaving engagement of the individual layers L1 . . . L18 of the profiled abrasive band 13 means that, from the second layer L2 onwards, several of the layers L are always in contact with the workpiece to be machined (not shown). In this way, fresh abrasive grain 18 is continuously released during the grinding process.

[0069] The abrasive band 13 is a continuous band having a first end 21 and a second end 22. The first end 21 lies in the circumferential side 4 and the second end 22 terminates at the supporting body 5. The abrasive band 13 has a constant width B over its entire length, or a constant axial extension with respect to the axis of rotation R. The abrasive band 13 comprises, here merely by way of example, three partial bands 23, 24, 25, which are arranged one behind the other in the winding direction and are connected or bonded to one another. In principle, however, it is also possible for the partial bands 23, 24, 25 to be loosely adjacent to one another. Furthermore, it is also possible that the abrasive band 13 is a continuous abrasive band that has consistent grinding properties along its length. The winding direction is indicated by the arrow W in FIG. 3. The winding direction W is, in this case, in the same direction as the direction of rotation of the drive, which is indicated by the arrow A in FIG. 3. In principle, however, it is also possible that the winding direction W is opposite to the drive direction of rotation A, whereby the removal rate, i.e. the aggressiveness of the grinding tool 1, can be decreased.

[0070] The partial bands 23, 24, 25 differ from each other in their grinding properties. The first partial band 23 extends at least approximately over the band section of the abrasive band 13 forming the first layer L1. The backing 14 of the first partial band 23 is, here merely exemplary, made of paper, in order to achieve a rapid degradation of the first layer L1. The subsequent layers L2, L3 are formed by the second partial band 24, in which, here merely by way of example, the backing 14 is made of a woven fabric. Thus, compared to the first partial band 23, the second partial band 24 is more resistant and allows higher removal rates. The radially more inner layers L4 . . . L18 are formed by the third partial band 25, whose backing 14 is also made of a fabric. Unlike the previous two partial bands 23, 24, the third partial band 25 has abrasive grains 18 of finer grain size to allow fine grinding. In this way, at the beginning of the grinding process, the grinding tool 1 initially allows a high removal rate while producing a uniform surface on the workpiece. When the fourth layer L4 and the other radially inner layers L5 . . . L18 are reached, the removal rate of the grinding tool 1 decreases and the grinding pattern becomes increasingly refined. In principle, however, it is also possible for the abrasive band 13 to have consistent abrasive properties along its entire length.

[0071] Furthermore, the grinding tool 1 has two stabilizing layers 26, 27, in particular ring shaped, between which the abrasive band 13 and the supporting body 5 are held. The stabilizing layers 26, 27 connect the abrasive band 13 to the supporting body 5. In FIG. 1 it can be seen that the stabilizing layers 26, 27 overlap the abrasive band 13 and the supporting body 5 on both sides, in particular completely. Thus, the support section 39 has a multilayer structure. Each of the stabilizing layers 26, 27 is a self-contained, inherently stable layer that can degrade along with the abrasive band 13 during the grinding process. Furthermore, the stabilizing layers 26, 27 have aligned central bores for receiving the bore ring 12, which extends through both stabilizing layers 26, 27 and the supporting body 5 embedded therebetween. The first stabilizing layer 26 closes with the first main tool side 2 and the second stabilizing layer 27 closes with the second main tool side 3 of the grinding tool 1. The stabilizing layers 26, 27 extend over the grinding section 6 and, at least partially, over the supporting body 5. The stabilizing layers 26, 27 each have a cured binder 28 in which reinforcing interlining 29, 30, such as the circular blanks of fabric material shown in FIGS. 5 and 8, can be inserted or embedded, respectively.

[0072] The abrasive band 13 is bonded to the stabilizing layers 26, 27 via the binder 28. Specifically, the abrasive band 13 has an edge region 31, 32 at each axial end with a circumferential edge 33, 34 delimiting the abrasive band 13. Due to the winding of the abrasive band 13, the respective circumferential edge 33, 34 follows the trace of a spiral. It can be seen in FIG. 10 that gaps or spaces 35 can be formed between the individual layers L1 . . . L18, which can occur despite the layers L1 . . . L18 preferably being close together, mainly because of the rough surface of the grinding layer 16. During the manufacture of the grinding tool 1, it can be pressed, whereby the binder 28, which is still flowable during the manufacturing process, partially penetrates from the stabilizing layers 26, 27 into the spaces 35 before it hardens there. The edge regions 31, 32 provided with the cured binders 28, 28 each have an axial extent B31, B32 of less than, here only exemplary, 10 percent of a width B13, respectively axial extent of the abrasive band 13. Advantageously, the remaining central grinding region 20 extending between the two edge regions 31, 32 has an axial extension B20 corresponding to at least 80 percent of the width B13 of the abrasive band 13. In the grinding region 20, the individual layers L1 . . . L18 of the abrasive band 13 lie unconnected or loosely against each other. The thickness of the grinding tool 1 corresponds to the axial extension A6, which is greater than the width B13 of the abrasive band 13 by the thicknesses of the two stabilizing layers 26, 27. Their layer thicknesses are a maximum of 2 millimeters, whereby the binder 28, 28 penetrated in the edge regions 31, 32 has no influence on the determination of the layer thicknesses.

[0073] Furthermore, the binder 28 may be arranged in a transition region 36 formed between the radially innermost layer L18 and the outer circumferential edge 9 of the supporting body 5, or may have penetrated and hardened during the pressing process when the grinding tool 1 is manufactured. It can be seen in FIG. 1 that the supporting body 5 can be arranged to engage in the profile geometry of the radially innermost layer L18, which is open toward the axis of rotation R. Accordingly, an outer diameter D5 of the supporting body 5 may be larger than an inner diameter D6 of the grinding section 6. Specifically, the outer diameter D5 of the supporting body 5 can be up to 30 millimeters larger than the inner diameter D6 of the grinding section 6. The abrasive band 13, in particular the radially innermost layer 19, thus surrounds the supporting body 5, in this case, in a V-shape or receives it in a V-shape. This radial engagement further increases the stability of the grinding tool 1. In principle, however, it is also possible for the supporting body 5 to end radially outside the abrasive band 13 or to end at the radially innermost layer 19.

[0074] FIGS. 4 to 9 show components of the grinding tool 1 as they may be provided prior to manufacture of the grinding tool 1. In FIG. 4, a label 37 is shown that may be ad-hered to the first main tool side 2. The label 37 may indicate information about the grinding tool 1 in a manner known per se. FIG. 5 shows the reinforcing interlining 29 for the first stabilizing layer 26. The reinforcing interlining 29 may be a circular blank made of a fabric material impregnated with the binder 28. FIG. 6 shows a primary material 38 in the form of a band-shaped abrasive on backing from which the profiled abrasive band 13 can be made. The primary material 38 is spirally wound with the grinding layer 16 directed radially outward. FIG. 7 shows the two circular blanks 10, 11 made of fabric material impregnated with binder, from which the supporting body 5 is manufactured. FIG. 8 shows the reinforcing interlining 30 for the second stabilizing layer 27, which may correspond to the reinforcing interlining 29 shown in FIG. 5. FIG. 9 shows the bore ring 12.

[0075] To make the grinding tool 1, the second reinforcing interlining 30 may first be placed in a mold (not shown) having a cylindrical wall and a bottom. Subsequently, the coiled primary material 38 can be positioned in the mold on the lower reinforcing interlining 30. in the process, the radially outermost layer of the primary material 38 rests against the cylindrical wall of the mold. Further, the two fabric circular blanks 10, 11 are inserted into the center of the spirally wound primary material 38, and then the upper reinforcing interlining 29 is placed on the wound primary material 38. Optionally, the label 37 may be placed on the upper reinforcing interlining 29. In the further manufacturing process, a pressure plate, the outer diameter of which corresponds to the inner diameter of the cylindrical wall of the mold, is placed on the label 37 or the upper reinforcing interlining 29, and the components inserted in the mold for the grinding tool 1 are pressed together under a pressure force and temperature acting along the axis of rotation R to form the grinding tool 1. During pressing, the wound primary material 38 yields to the compressive force, whereby the primary material 38 can only buckle towards the center due to the radially outer support provided by the mold and the radially inner support provided by the fabric circular blank 10, 11. In the process, the primary material 38 buckles in a V-shape in the radially inner layers and, in particular, the radially outermost layer L1 buckles in a U-shape. The buckled primary material 38 forms the profiled abrasive band 13. As a result of the buckling of the primary material 38, the outer circumferential edge 9 of the supporting body 5 can and may deform. To further affect the buckling of the primary material 38, the mold may have chamfers on the cylindrical wall at the top and bottom edges. Furthermore, the bottom of the mold can have a central elevation on which the fabric circular blanks 10, 11 for the supporting body 5 can be placed. During pressing, the binder 28 partially penetrates into the spaces 35 and into the transition area 36 and, in the cured state, thus bonds the abrasive band 13 to the supporting body 5.

[0076] In FIG. 11, a grinding tool 40 according to a second embodiment is shown in crosssection with respect to the axis of rotation R. The grinding tool 40 differs from the aforementioned grinding tool 1 according to the first embodiment, as shown in FIGS. 1 to 10, only in that the grinding tool 40 is designed without a carrier. In this respect, reference is made to the above description with regard to the similarities. Identical or modified details are marked with the same reference signs. The grinding tool 40 can be a grinding sleeve with the abrasive band 13, which is wound in several, here only exemplary seven, layers L1 . . . L7 around the axis of rotation R. The radially inner, second end 22 of the abrasive band 13 terminates on an inner circle formed concentrically around the axis of rotation R, as shown in FIG. 11. In the center of the grinding tool 40, for example, a pin or mandrel can be used to connect the grinding tool 40 to the rotary drive machine.

[0077] In FIG. 12, a grinding tool 50 according to a third embodiment is shown in cross-section with respect to the axis of rotation R. The grinding tool 50 differs from the aforementioned grinding tool 40 according to the second embodiment, as shown in FIG. 11, in that the winding of the grinding tool 40 has a multilayer structure. In this respect, reference is made to the above description with regard to the similarities. Identical or modified details are marked with the same reference signs. Specifically, the winding has, here merely exemplary, eight layers formed by the abrasive band 13 and seven further abrasive bands 51, which are wound together with the abrasive band 13 around the axis of rotation R in several, here merely exemplary two, layers L1, L2. The abrasive bands 13, 51 may have the same or different abrasive properties. However, it is also possible for the abrasive bands to be the same length or different lengths. The multilayer winding shown here in connection with the grinding tool 50 can be applied analogously to the grinding tool 1.

LIST OF REFERENCE NUMBERS

[0078]

TABLE-US-00001 1 Grinding tool 2 Main tool side 3 Main tool side 4 Circumferential side 5 Supporting body 6 Grinding section 7 Main body side 8 Main body side 9 Outer circumferential edge 10 Circular blank 11 Circular blank 12 Bore ring 13 Abrasive band 14 Backing 15 Band side 16 Grinding layer 17 Binder matrix 18 Abrasive grains 19 Band side 20 Grinding region 21 End 22 End 23 Partial band 24 Partial band 25 Partial band 26 Stabilizing layer 27 Stabilizing layer 28 Binder 29 Reinforcing interlining 30 Reinforcing interlining 31 Edge region 32 Edge region 33 Peripheral edge 34 Peripheral edge 35 Space 36 Transition area 37 Label 38 Primary material 39 Support section 40 Grinding tool 50 Grinding tool 51 Abrasive band A Drive direction of rotation B Width, axial extension D Diameter L Layer R Axis of rotation W Winding direction