CN117769480A

CN117769480A - Abrasive tool and method of manufacturing an abrasive tool

Info

Publication number: CN117769480A
Application number: CN202280039117.3A
Authority: CN
Inventors: M·塞勒
Original assignee: Lucas Elzet Co ltd
Current assignee: Lucas Elzet Co ltd
Priority date: 2021-05-31
Filing date: 2022-05-27
Publication date: 2024-03-26
Also published as: DE102021114052A1; KR20240036516A; EP4347186A1; WO2022253711A1

Abstract

The invention relates to an abrasive tool (1; 40; 50) which can be driven in rotation about a rotation axis (R), comprising: abrasive belt (13) wound around a rotation axis (R) in a spiral form with a plurality of superimposed layers (L) and having an abrasive layer (16) on a belt side (15) facing away from the rotation axis, characterized in that the wound abrasive belt (13) has a convexly curved design with respect to the rotation axis (R) in a longitudinal section along the rotation axis (R) and that the layers (L) of the abrasive belt (13) are arranged to fit radially into each other. The invention also relates to a method for producing an abrasive tool (1; 40; 50).

Description

Abrasive tool and method of manufacturing an abrasive tool

Technical Field

The invention relates to an abrasive tool which can be driven to rotate about a rotational axis and which comprises an abrasive belt which is wound in spiral form about the rotational axis with a plurality of superimposed layers and which has an abrasive layer on the belt side facing away from the rotational axis. Furthermore, the invention relates to a method for producing such an abrasive tool.

Background

US 4,625,466A discloses an abrasive disk with an abrasive tape wound around an axis of rotation. The abrasive belt has a radially outwardly facing abrasive layer and a radially inner foam layer. The abrasive layer extends parallel to the axis of rotation. Furthermore, the grinding disk has a support plate to which the grinding belt is fastened with its circumferential edge axially aligned with the rotation axis.

US2 725,693A discloses a sand roller made of a strip of abrasive cloth rolled into a cylinder around a small central mandrel, the sand roller being held together by an adhesive layer extending along at least a portion of the length of the sand roller. The cloth strip is rectangular and wound into a cylinder with the cloth surface facing outwards. Circular grooves are provided in the sand roller, extend outwardly around the periphery of the sand roller, and are recessed inwardly toward the central spindle.

DE 37,204 A1 describes an axially compressed disc-shaped lamellar body which consists of intermeshed fibrous material and is made of metal fibers. These layers are layers of helically wound fiber strands.

Disclosure of Invention

Based on this prior art, it is an object of the present invention to provide an abrasive tool with which a uniform abrasive pattern can be obtained on a workpiece to be (mechanically) processed during the grinding process. It is a further object of the present invention to provide a method of manufacturing such an abrasive tool, with which a uniform abrasive pattern can be obtained on a workpiece to be machined during the grinding process.

As a solution, an abrasive tool of the above-mentioned type is proposed, in which the wound abrasive belt is convexly curved in longitudinal section along the rotation axis relative to the rotation axis (R), and the layers of the abrasive belt project radially into each other.

For the purposes of the present invention, the terms "radial" and "axial" are used as abbreviations for "radial with respect to the axis of rotation" and "axial with respect to the axis of rotation", respectively.

Advantageously, the abrasive tool continuously exposes fresh abrasive material to the working surface on the workpiece to be processed. The abrasive belt is consumed during the abrading process because during use the layers of the abrasive belt deteriorate from radially outward to radially inward so that the outer diameter of the abrasive tool becomes smaller and smaller. However, due to the radial engagement of the layers of the abrasive tape, at least a portion of the area of the abrasive surface of the wound abrasive tape extending over the layers is always exposed on the outer circumferential surface of the winding. This again creates a reproducible, uniform surface on the workpiece. Since the grinding surface faces away from the axis of rotation, the rotationally drivable grinding tool can be applied to the workpiece to be machined with the peripheral surface of the grinding tool, in particular with windings. Thus, the abrasive tool is particularly useful for machining welds, fillet welds, and joints.

Each layer is formed by longitudinal belt sections of the abrasive belt, each extending over one turn of the wound abrasive belt. Preferably, the abrasive belt is a self-contained continuous belt material that can extend over all layers of the winding. In particular, all layers of the abrasive belt are on top of each other; the abrasive tape is actually rolled up. The first layer starts at a first radially outer end of the abrasive belt and correspondingly ends with a first winding around the rotation axis. The last layer terminates at a second radially inner end of the abrasive belt. Since the outer peripheral radius of the windings becomes smaller with each radially inner layer, the longitudinal belt section of the abrasive belt becomes correspondingly shorter with each layer. Preferably, the abrasive tape is wound around the axis of rotation for at least two layers and in a further preferred manner for at least ten layers. In particular, the winding has at least two layers and at most 150 layers of abrasive tape. Preferably, the winding has at least 3 layers and at most 50 layers of abrasive tape, and further preferably at least 5 layers and at most 30 layers of abrasive tape. The windings may be designed without a carrier, whereby the second radially inner end of the abrasive belt may end at the rotation axis or in the centre of the windings. Alternatively, the windings may terminate in an inner circumference, such that the windings may have a central, axially extending recess into which a shaft for connecting the grinding tool to the rotary drive machine or a support for stabilizing and/or connecting the grinding tool to the rotary drive machine may be inserted or fitted. The windings, the respective wound abrasive tape, form the abrasive segments of the abrasive tool.

Due to its convex bulge design, the abrasive belt has a profile geometry which is open to the axis of rotation. Profile geometry preferably means geometry originating from a longitudinal section through the abrasive belt along the rotation axis. In particular, the profile geometry has a U-shape and/or V-shape at least partially along the belt length of the abrasive belt. The belt length of the abrasive belt corresponds to the extension of the abrasive belt over all layers or the distance between the ends of the abrasive belt in the unreeled state. The profile geometry may also be at least partially L-shaped and/or W-shaped and/or C-shaped. The contour of the abrasive belt can be produced, for example, by shaping a strip-shaped raw material. The raw material may be a flat abrasive, such as an abrasive material on a backing. In principle, it is also possible to provide an abrasive tape to be wound which has been correspondingly preformed. In particular, the radially further inward layer of the abrasive belt may have a V-shaped profile geometry, whereby for each radially further outward layer the profile geometry may be changed to a U-shape, in particular a continuous U-shape. Advantageously, the outermost layer is U-shaped and the outermost abrasive layer thus forms a rounded, outwardly curved abrasive effective circumferential surface of the abrasive tool.

Furthermore, it may be provided that the radially inner layer of the grinding belt is axially partially covered by an adjacent radially outer layer of the grinding belt with respect to the axis of rotation. Due to this staggered form of the individual layers of the abrasive belt, once the outermost layer has been at least partially worn away, several layers of the abrasive belt are always exposed on the peripheral surface of the abrasive tool, at least in certain areas. This ensures that a consistent grinding pattern is maintained during the grinding process.

Further, the abrasive tool may have a first main tool side and a second main tool side facing away from the first main tool side. The lapping tape may be axially arranged between the first main tool side and the second main tool side with respect to the rotation axis. The second main tool side may be the rear side of the grinding tool or the side facing the drive machine. In principle, however, it is also conceivable and possible for the grinding tool to be clamped on the spindle of the drive machine, with the first main tool side facing the drive machine.

The abrasive tool may have at least one stabilizing layer. This may increase the stability of the abrasive tool, in particular the stability of the abrasive segment. Furthermore, at least one stabilizing layer may provide lateral or wing protection against accidental scraping of the workpiece being processed. In particular, the abrasive tool may be at least partially covered by one of the at least one stabilizing layer on its first and/or second main tool side, respectively. The abrasive tape may be attached to at least one stabilizing layer. This secures the rolled up abrasive tape in place in a simple manner, preventing accidental rolling up or unrolling during storage of the abrasive tool or during the grinding process. The at least one stabilizing layer may have a maximum layer thickness of 2 millimeters and/or a minimum layer thickness of 0.4 millimeters. As a result, the at least one stabilizing layer may on the one hand provide a sufficiently stable support for the abrasive belt and on the other hand may continuously deteriorate with the abrasive belt during the grinding process. Preferably, the layer thickness is less than 1.5 mm, and in a further preferred manner may be between 1.0 mm and 0.6 mm.

According to one embodiment, the abrasive tool may have two stabilizing layers, a first stabilizing layer facing a first main tool side of the abrasive tool and a second stabilizing layer facing a second main tool side of the abrasive tool. The axial fixation of the abrasive belt on both sides provides a particularly stable abrasive tool. In a manner known per se, labels or the like can be applied to the main tool side of the abrasive tool, but these labels or the like have no effect on the abrasive properties or durability of the abrasive tool per se.

In particular, at least one of the stabilizing layers is an inherently stable self-contained layer. Advantageously, during use of the abrasive tool, at least one stabilizing layer may deteriorate with the wound abrasive tape. The at least one stabilizing layer may axially overlap the abrasive belt or extend over the abrasive segments of the abrasive tool. The peripheral edge of the abrasive belt facing the at least one stabilizing layer may be bonded to the at least one stabilizing layer. The respective circumferential edges are formed at one axial end of the wound abrasive belt and follow a helical path as a result of the winding of the abrasive belt. In this way, the abrasive belt can be secured at least one of the two open axial ends. Advantageously, the at least one stabilizing layer also allows the use of a particularly thin abrasive belt that tears during the grinding process without such lateral stabilization. For example, such a thin abrasive belt may have a paper backing with abrasive particles applied thereto.

Furthermore, at least one of the stabilizing layers may have an adhesive which extends into the intermediate space formed between the abrasive belt layers in the edge region of the abrasive belt facing the respective stabilizing layer. The side of the belt facing away from the axis of rotation has an abrasive layer, which may have a roughened surface, while the side of the belt facing the axis of rotation may have a flat, smoother surface, which means that when the abrasive tool is manufactured, an intermediate space is formed between adjacent layers, into which the adhesive may penetrate. Preferably, at least one edge region of the abrasive belt provided with the adhesive extends over as small a proportion as possible of the axial extension of the abrasive belt, in order to keep the abrasive layer free over as large a region as possible. This is because the adhesive may adhere to the edge region of the abrasive layer, which may locally impair the removal rate of the abrasive belt. This has the advantage that at least one edge region has no or little grinding effect and therefore prevents scraping of the workpiece in the event of grinding of the tool to unintentionally contact the workpiece to be machined on the respective main tool side. Thus, the at least one stabilizing layer may have a dual function, on the one hand increasing the stability of the abrasive belt and on the other hand providing lateral or flank protection. In particular, the axial extension of the respective edge region is less than the width, i.e. 20% of the axial extension of the abrasive belt, and further preferably less than 10% of the width, i.e. the axial extension of the abrasive belt, and even further preferably less than 5% of the width, i.e. the axial extension of the abrasive belt.

In a preferred manner, the layers are at least partially unconnected to each other. In other words, the layers are not at least partially glued together, but are loosely held against each other. This creates a consistently reproducible, uniform surface on the workpiece and increases the removal rate of the abrasive tool. If the abrasive tape is attached to at least one stabilizing layer, the unattached portion may be a central abrasive region of the abrasive tape, which may be axially adjacent to at least one edge region provided with adhesive. If the abrasive belt is fixed on both sides, a central abrasive region can be formed between the two edge regions accordingly. Preferably, the central grinding zone of the grinding belt extends over at least 60% of the axial extension of the grinding belt, and in a further preferred manner may be between 70% and 90%. In a convenient manner, the central abrasive region of the outermost layer is located in the peripheral surface of the abrasive tool. As the abrasive tool wears, the circumferential surface displaces radially inward. Accordingly, the grinding tool can grind a workpiece to be machined with the outer peripheral surface of the grinding tool. This makes the abrasive tool particularly suitable for machining welds, fillet welds and joints.

The binder may be a resin or an adhesive. The binder in the abrasive tool may have cured. Advantageously, the binder is thermally stable in the cured state to withstand the temperatures generated during grinding. In particular, the binder may be thermosetting. In particular, phenolic resins may be provided as binders, although other resins or bonding systems may also be used, such as in particular epoxy resins, polylactides, also known as polylactic acid, and lactate salts thereof, polyurethanes, and mixtures thereof. In addition, the binder may also be or include a polymer foam.

The at least one stabilizing layer may comprise a reinforcing liner, which may be provided with or embedded in an adhesive. The reinforcing liner may comprise a fabric and may be, for example, a glass or other mineral fiber fabric, a natural fiber fabric, a metal fabric such as a wire plant, or the like, or a combination thereof. It is also possible to arrange several reinforcing liners one above the other in at least one stabilizing layer to adjust the stability. Instead of a fabric, it is also possible to provide a scrim, knitted fabric, nonwoven, paper, vulcanized fibre, plastic disc or other reinforcing material which performs the function of stabilizing, fixing and/or reinforcing the abrasive tool, in particular the wound abrasive belt. This can also be achieved by (individual) fibres, which may be added to the binder, for example.

Furthermore, the binder of the at least one stabilizing layer may be mixed with the filler. The filler may include, for example, quartz powder, amorphous silica, rutile, and the like. In particular, the filler is sandable and may include a fluoride such as KBF4 or cryolite, or other substances that are otherwise beneficial to the abrading process, such as lubricants or anti-adherents, that reduce clogging of the abrading tool during the abrading process.

Furthermore, at least one stabilizing layer may include or act as a support for the abrasive. This allows the abrasive tool to be designed according to different requirements. For example, the at least one stabilizing layer may include a grinding disc, which may have a fabric backing. The abrasive disc may be a cutting wheel, an abrasive disc or the like, or a bonded abrasive. The at least one stabilizing layer may be a support for another abrasive disc, in particular for a lamellar abrasive disc or another of the above-mentioned abrasive discs.

The abrasive tool may have a central support section that may be connected radially inward to the abrasive section. The wound abrasive belt may be arranged in a circumferential direction around the rotation axis of the support section. Preferably, the grinding section corresponds at least substantially to an annular section formed concentrically about the axis of rotation and having an inner diameter and an outer diameter. Preferably, the outer diameter of the grinding section corresponds to the outer diameter of the grinding tool, which outer diameter is located in the circumferential surface of the grinding tool. In particular, the inner diameter of the grinding section corresponds to at least two-thirds of the outer diameter of the grinding tool, and further preferably corresponds to at least about five-sixths of the outer diameter of the grinding tool. This allows higher peripheral speeds to be achieved during grinding. Furthermore, the grinding segments are designed to be sufficiently far radially outward that the rotary drive machine does not interfere with or strike the workpiece during grinding, even when the radially innermost layer of the grinding belt is worn.

The grinding tool may have a central support body, in particular concentric with the rotation axis, around which the grinding belt is arranged. In particular, the support body may radially engage a contour of a radially innermost layer of the abrasive belt, which contour is open to the axis of rotation. This increases the stability of the abrasive tool. The greater the axial extension of the grinding belt, the deeper the support body can be inserted or arranged in the contour of the grinding section or radially innermost layer of the grinding belt which is open to the rotation axis. In principle, however, the support body can also be arranged radially outside the winding or terminate at the radially inner end of the grinding section. The support body may be arranged at a horizontal position of the center of the abrasive belt with respect to the rotation axis, or may be arranged toward the second main tool side. According to one embodiment, the abrasive tool may be an abrasive disk.

Furthermore, an abrasive belt may be attached to the support body. In particular, the abrasive belt is attached to the support body by means of at least one stabilizing layer. The at least one stabilizing layer may thus axially overlap the abrasive belt or extend over the abrasive section and may extend at least partially over the support body. This prevents the abrasive belt from separating or rolling up from the support during the grinding process. Similar to the geometry of the abrasive disk, the shape of the at least one stabilizing layer may be annular. The reinforcing liner may be designed as a circular blank, in particular with a central hole opening, which may be impregnated with adhesive.

Furthermore, the support section and/or the support body may be plate-shaped. The support section may have a first body side and a second body side opposite the first body side. The two body sides are axially spaced as the main tool side. Furthermore, the support body may have a peripheral edge, wherein the abrasive belt is arranged around the peripheral edge. Preferably, the support body terminates radially outwardly at the peripheral edge. The support body may have a circular peripheral edge, which may be arranged concentrically to the axis of rotation. The abrasive belt may be disposed in a spiral around the peripheral edge and may be wound in the form of an archimedes spiral. The first radially outer end of the abrasive belt may terminate at the outer periphery of the abrasive disc, and the second radially inner end of the abrasive belt may terminate at the outer peripheral edge of the support body. In particular, the second end of the abrasive belt, in particular the abrasive belt as a whole, is at least slightly spaced apart from the support body. Slightly may mean that the distance between the second radially inner end of the abrasive belt and the support body is at most 20 mm. Preferably, the abrasive belt is indirectly connected to the support only via the adhesive of the at least one stabilizing layer and optionally the adhesive in combination with the support.

Preferably, the axial extension of the abrasive belt is greater than the axial extension of the support body. This provides a stable abrasive disk. The transition between the grinding section and the central support section may be stepped or rounded. In the abrasive disk, the ratio of the maximum axial extension to the outer diameter of the abrasive disk is preferably less than 1 to 1. Furthermore, the axial extension of the abrasive disk along the wound abrasive tape may be at most 50 mm, and preferably at most 20 mm. The diameter of the outer periphery of the abrasive disc may preferably be greater than 95 millimeters. Preferably, the diameter of the outer periphery of the abrasive disk is in the range of 95 to 230 mm, and further preferably in the range of 95 to 160 mm, and even further preferably in the range of 125 to 150 mm. The diameter of the outer peripheral edge of the support body is smaller than the diameter of the outer periphery of the grinding disc. Preferably, the diameter of the outer peripheral edge of the support is about 15% to 50% of the diameter of the outer periphery of the abrasive disk, and in a further preferred manner, at least about 25% to 40% of the diameter of the outer periphery of the abrasive disk.

A centrally arranged and axially extending bore may be formed in the support body to accommodate a spindle of a drive machine for driving rotation of the abrasive tool about the axis of rotation. Furthermore, the support body can be cranked in order to be able to receive a clamping nut for securing the grinding tool to the spindle of the rotary drive machine in the central cranked region or in the recessed or axially recessed region. In the centre of the support body, or in the centre hole, a threaded bushing, for example a hole with an eyelet, or other means of fastening the grinding disc to the rotary drive machine, such as a bushing, an X-lock mount, etc., may be provided in order to be able to fasten the support body to the rotary drive machine directly or indirectly via a separate support plate. The support body may also have a shaft, in particular a permanently integrated shaft, for connecting the grinding disk to the drive machine.

According to one embodiment, the abrasive tool may be an abrasive sleeve, wherein the abrasive belt may be configured as a carrier-free winding. Such windings are also referred to as supportless windings or coreless windings. The grinding sleeve may furthermore have a central support body around which the grinding belt is arranged. In the example of a grinding sleeve, the ratio of the axial extension to the outer diameter of the grinding sleeve is preferably greater than 1 to 1. As an alternative to the plate-like design of the support body, it is also possible to design a pin-like support, on which the helically wound grinding belt of the grinding sleeve can be attached or plugged.

The support of the abrasive tool may have damping vibration attenuation characteristics. In addition, the support may be used to stabilize the abrasive tool. Suitable materials for the support include glass fabrics or linen, which may be provided with binders, or materials made from wood pulp, cellulose, hemicellulose or waste paper by gluing or pressing together, for example: cardboard, or plastic such as polyurethane, or rubber, etc.

Preferably, the abrasive belt is a coated abrasive or abrasive cloth. Alternatively, the abrasive belt may be a nonwoven without abrasive particles and/or a nonwoven with abrasive particles, which may also be referred to as a sanded nonwoven. In particular, the abrasive belt is flexible. This allows the abrasive belt to be wound as tightly as possible around the axis of rotation, so that the layers of windings can be stacked tightly on top of each other. Preferably, the abrasive belt has a constant width, i.e. an axial extension over the length of the belt. In particular, the abrasive belt has an abrasive layer, which may also be referred to as the front side, only on the side of the belt facing away from the axis of rotation. Specifically, the abrasive layer extends over the entire surface of the front side of the abrasive belt. In addition, the abrasive layer may have abrasive particles that may be embedded in a matrix or binder. For example, the matrix may be a plastic matrix or a resin matrix. The abrasive particles may preferably be oriented in a primary direction, particularly perpendicular to the backing of the abrasive belt. This can be achieved by, for example, electrostatic scattering, alignment in a magnetic field or even via mechanical application methods.

The backing may be a textile backing on which the abrasive layer may be applied, in particular on one side. The fabric backing or fabric support may comprise natural fibers, synthetic fibers, or mixtures thereof. Likewise, the backing may be made of a nonwoven material, such as nonwoven, paper, scrim, or other common backings in the abrasive art on a backing, including vulcanized fiber, or abrasive that is subsequently weakened or optionally recoated. Furthermore, the backing may be designed to be as thin and/or weakened as possible in order to be able to deteriorate rapidly during the grinding process. This allows the abrasive tool to release the abrasive layer onto the underlying layer faster, allowing for continued exposure of fresh abrasive to the work surface of the workpiece being processed. The thickness of the backing may be only sufficient to retain the abrasive layer on the backing. In particular, such a thin backing may be a paper or a thin woven or nonwoven material having a thickness of, for example, less than 250 microns. The backing may also be weakened by perforations, slits or the like.

Furthermore, the backing and/or matrix or binder of the abrasive layer may be provided with an abrasive aid or reinforced. Such grinding aids may include, for example, quartz powder, amorphous silica, rutile, etc., as fillers in at least one stabilizing layer. In particular, the grinding aid is an abrasive and may include a fluoride such as KBF4 or cryolite, or a substance that is otherwise useful in the grinding process such as a lubricant such as a sulfur compound, or a detackifier such as a stearate that reduces clogging of the grinding tool during the grinding process.

Specifically, the abrasive belt is formed in one piece. The grinding characteristics may be constant across the entire grinding belt. Alternatively, the abrasive belt may have sections with different abrasive properties. Furthermore, the abrasive belt may consist of several profiled belt-shaped sections. For example, the sections may be glued together. Since different sections are formed one after the other in the winding direction of the abrasive belt, different properties can be combined. For example, the radially outer layer of the belt may have coarser abrasive particles, while the radially inner layer of the belt may have finer abrasive particles. A combination of different abrasive particle types and sizes may enable a more versatile abrasive tool. Furthermore, combinations of different backings and/or different abrasive belts may open up a wider range of applications for abrasive tools. This may be an average higher grinding performance on different materials, or a better appearance of the work surface being machined on the workpiece, such as a finer surface, or better availability on a low power rotary drive machine.

The thicker the abrasive particles, the greater the thickness of the abrasive belt or portion of the belt. Thus, typically, the abrasive belt or portion of the belt having finer abrasive particles is thinner. Preferably, in contrast, an abrasive tool having generally more coarse grains may have fewer layers than an abrasive tool having more fine grains. This allows the abrasive tool to have a constant outer diameter regardless of the abrasive particles.

In addition, the abrasive tool may be designed to be driven in the direction of drive rotation. This may be indicated on a label of the abrasive tool, for example. The winding direction of the abrasive belt may correspond to the rotational driving direction. This provides a more durable abrasive tool. Alternatively, the winding direction of the abrasive belt may also be opposite to the rotational driving direction. This increases the removal rate of the abrasive tool, i.e., its aggressiveness.

According to one embodiment, the abrasive tool has a single layer winding comprising only one abrasive belt spirally wound in a plurality of stacked layers about an axis of rotation. Preferably, the superimposed layers of the abrasive belt are directly, at least partially, against each other. In the case of an abrasive tool having at least one stabilizing layer, at least partially directly adjacent to each other should comprise an adhesive for attaching the rolled up abrasive belt to the at least one stabilizing layer, which adhesive may be provided in the space between the layers of the abrasive belt in at least one edge region of the abrasive belt.

According to another embodiment, an abrasive tool includes a multi-layer winding having an abrasive tape and at least one other abrasive tape, wherein the abrasive tape and at least one other abrasive tape are at least partially stacked in multiple layers and are helically wound about an axis of rotation with the multiple stacked layers. In other words, the stacked abrasive belts are wound together about an axis of rotation, thereby forming a multi-layer structure. At least one other abrasive belt may be designed in the same manner as the profiled abrasive belt, so that reference is made herein in a simplified manner to the above description. In this way, different types of abrasive belts may be incorporated into the abrasive tool. In particular, the winding may have two, three, four, five, six, seven, eight or more than eight abrasive belts from at least one abrasive belt.

The abrasive strips form separate layers in the windings, the abrasive strips being unconnected to each other. The abrasive belts may be connected to each other at a radially inner end and/or at a radially further outer end. In addition, at least one other abrasive belt may have a shorter belt length than the abrasive belt. As a result, the winding may have multiple layers and a single layer. In particular, the radially inner layer is multilayered and the radially outer layer is single-layered. This gives the abrasive tool different abrasive properties, which result in different abrasive performance when the abrasive tool deteriorates and the outer radius is thus smaller. At the beginning of the grinding process, only the grinding belt may be located in the peripheral surface of the grinding tool, and at least one other grinding belt can engage the peripheral surface only when the windings are further degraded. In principle, the grinding belts can also have the same length, so that from the beginning the grinding belt and at least one further grinding belt extend over the periphery of the grinding disk, and all layers are correspondingly multilayered.

As a further solution, a method for manufacturing an abrasive tool of the aforementioned type is proposed, wherein the method comprises the steps of:

-providing a raw material in the form of a ribbon-like abrasive;

-helically winding the raw material around the rotation axis;

-arranging the wound raw material in a mould having a cylindrical wall with an inner diameter at least approximately corresponding to the outer diameter of the grinding tool to be produced;

-pressing the wound raw material in a direction along the rotation axis until the raw material flexes.

The belt abrasive preferably has an abrasive layer on only one side. The ribbon abrasive may be a planar abrasive. In principle, it is also possible to provide the abrasive material to be wound already shaped such that its cross section in the direction of the abrasive layer is convex. In this case, pressing the rolled stock material will cause the abrasive to flex farther than the already preformed material.

The method according to the invention gives the same advantages as described in connection with the grinding tool according to the invention, and reference is therefore made here by way of abbreviation to the above description. It should be appreciated that all of the above embodiments of the abrasive tool can be transferred to the method and vice versa. In general, the method according to the invention enables simple and cost-effective production of grinding tools with which a uniform grinding pattern can be produced on a workpiece to be processed during grinding.

The deformation of the otherwise flat raw material in the form of a belt causes the raw material to buckle or bend and the abrasive belt to have the desired profile geometry. Thus, the axial extension of the shaped abrasive belt produced by the shaping can be smaller than the width of the strip-shaped raw material. For example, the shaped abrasive belt may have an axial extension of about 10 millimeters, while the strip stock material may have a width of about 13 millimeters. The wound raw material may be subjected to compressive forces acting along the axis of rotation during extrusion until the raw material, in particular the backing of the abrasive, yields and buckles. In the flexed state, the abrasive belt receives the desired profile geometry. The fact that the raw material is extruded in a wound or coiled state has shown that the radially inner layer in particular obtains a V-shape and that the profile geometry of the abrasive belt is transformed into a U-shape by the radially outer layer. This is advantageous because it gives the outer peripheral surface of the grinding tool a spherical grinding surface, in particular a spherical grinding surface which is curved outwards due to the radially outermost layer.

The mould may have a bottom on which the rolled raw material is placed. The cylindrical wall supports the raw material from the radially outer side and prevents the windings from deflecting outwardly so that the raw material can only flex radially inwardly during pressing. In particular, a compressive force acts on the raw material in the direction of the rotation axis or along a longitudinal axis about which the cylindrical wall is arranged concentrically, until the raw material flexes. This allows the creation of a profile geometry that is open towards the axis of rotation.

Drawings

Preferred embodiments of the present invention are illustrated in the accompanying drawings and described below. In the accompanying drawings:

FIG. 1 shows a longitudinal cross-sectional view of an abrasive tool according to a first embodiment, taken along line I-I shown in FIG. 3;

FIG. 2 illustrates a perspective view of the abrasive tool of FIG. 1;

FIG. 3 illustrates a top view of the abrasive tool of FIG. 1;

FIG. 4 shows a plan view of a label for an abrasive tool;

FIG. 5 illustrates a plan view of a first reinforcing liner for use in manufacturing an abrasive tool;

FIG. 6 shows a plan view of a rolled stock material used to make an abrasive tool;

FIG. 7 illustrates a top view of a circular blank for manufacturing an abrasive tool;

FIG. 8 illustrates a plan view of a second reinforcing liner for use in manufacturing an abrasive tool;

FIG. 9 shows a plan view of an grommet for use in manufacturing an abrasive tool;

FIG. 10 illustrates a partial view of an enlarged longitudinal cross-sectional view of the abrasive tool of FIG. 1 along line X-X shown in FIG. 3;

FIG. 11 shows a cross-sectional view of an abrasive tool according to a second embodiment;

fig. 12 shows a cross-sectional view of an abrasive tool according to a third embodiment.

Detailed Description

Fig. 1 to 10 show a first embodiment of an abrasive tool 1 according to the present invention and are described together hereinafter. The grinding tool 1 is designed as a grinding disc 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, and a circumferential side 4. Furthermore, the grinding tool 1 has a central bearing section 39 arranged concentrically about the rotation axis R and a grinding section 6 arranged radially outside the bearing section 39.

The support section 39 has a first body side 7 and a second body side 8 facing away from the first body side. The support section 39 comprises a support body 5, which support body 5 forms the shape of a plate, in particular by pressing. The support body 5 is here by way of example only made from two resin-impregnated round blanks 10, 11 which are pressed together one on top of the other. The two circular blanks 10, 11, as shown in fig. 7, may be circular blanks of fabric. Centrally, the bearing section 39 has a recess 41 which is formed concentrically with respect to the rotation axis R and has a central bore in which an annular ring 12, for example, 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 (not shown). The spindle nut is then supported on the first body side 7 of the support section 39 and can be received in the recess 41 to prevent undesired contact with the workpiece being machined.

The grinding section 6 has a grinding belt 13, the grinding belt 13 being arranged as a winding around the peripheral edge 9 of the support body 5. The abrasive belt 13 is spirally wound around the rotation axis R with a plurality (here, illustratively eighteen) of stacked layers L1, L2, L18. This allows for a single layer winding. In principle, however, the winding can also be a multi-layer winding with several such abrasive belts 13. The abrasive belt 13 is flexible and may be a sand on a backing 14. As shown in fig. 10, the abrasive belt 13 has an abrasive layer 16 on a first belt side 15, which may also be referred to as front side, facing away from the axis of rotation R. The abrasive layer 16 covers the entire surface of the front side 15 of the abrasive belt 13. The sand layer 16 has abrasive particles 18 embedded in a binder matrix 17 and retained on the backing 14. On the other hand, no further abrasive layer is applied to the abrasive belt 13 on a second belt side 19, which may also be referred to as rear side, facing away from the first belt side 15.

The grinding belt 13 is shaped in longitudinal section along the rotation axis R and has a profile geometry that is open towards the rotation axis R. The layers L1 … L18 of the abrasive belt 13 are arranged to extend radially towards each other, wherein the respective radially inner layer L2 … L18 of the abrasive belt 13 axially overlaps at least partly the adjacent radially outer layer L1 … L17 of the abrasive belt 13. In fig. 1 and 10, it can be seen that the profile geometry can have at least partially a U-shape and a V-shape as seen in longitudinal section. Here, the first radially outermost layer L1 has a U-profile geometry, and the radially inner layers L2, L3, …, L18 have V-profile geometries.

Due to the U-profile geometry of the first layer L1 of the abrasive belt 13 here, the circumferential side 4 of the abrasive tool 1 is bent radially outwards. The camber angle is greatest in the central grinding region 20 of the grinding tool 1. The pre-curved central grinding zone 20 is located at least substantially on a circumference having a diameter defining the outer diameter D1 of the grinding tool 1 due to the helical windings. The outer diameter D1 is greater than the maximum axial extent B1 of the sand tool 1 that the grinding tool 1 occupies in the grinding section 6. The ratio between the axial extension B1 of the grinding tool 1 and the outer diameter D1 is preferably less than 1 to 1, and is here about 1 to 10 by way of example only. The support body 5 has an axial extension B5 which is smaller than the axial extension B1 in the grinding section 6. The support body 5 is thus axially offset relative to the grinding section 6, whereby the transition between the grinding section 6 and the support body 5 can be stepped. The grinding tool 1 is thus particularly suitable for machining welds and fillet welds and joints.

At the beginning of the grinding process, the strip section of the grinding layer 16 extending over the first layer L1 is exposed in the circumferential side 4 of the sand tool 1. Then, the further radially inner layer L2 … L18 is still completely covered by the first layer L1. In fig. 1, only a subset of the nineteen layers in this example are labeled with reference numerals for clarity. In use, the abrasive tool 1 is typically placed with the central abrasive region 20 against the working surface of the workpiece to be machined. Thus, the layer L1 surrounding the central grinding zone 20 wears first. Once it wears in the central grinding zone 20, the strip section of the grinding layer 16 extending over its subsequent layer L2 is already exposed in the central grinding zone 20. Then, the two outermost layers L1, L2 simultaneously participate in the grinding process with the grinding effect. During grinding, 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 rotation axis R and continuously displaced towards the rotation axis R. The individual layers L of the abrasive belt 13 wear continuously from the radially outer side to the radially inner side so that the outer diameter of the abrasive tool 1 becomes smaller and smaller. Fig. 10 shows that the interdigitation of the individual layers L1 … L18 of the profiled abrasive tape 13 means that, starting from the second layer L2, several layers L are always in contact with the workpiece (not shown) to be processed. In this way, new abrasive particles 18 are continuously released during the grinding process.

The abrasive belt 13 is a continuous belt having a first end 21 and a second end 22. The first end 21 is located in the circumferential side 4 and the second end 22 terminates in the support body 5. The abrasive belt 13 has a constant width B over its entire length or a constant axial extension with respect to the rotation axis R. The grinding belt 13 here comprises, by way of example only, three partial belts 23, 24, 25 which are arranged one after the other in the winding direction and are connected or bonded to one another. In principle, however, the partial bands 23, 24, 25 can also be loosely adjacent to one another. Furthermore, the abrasive belt 13 may also be a continuous abrasive belt having uniform abrasive properties along its length. The winding direction is shown by arrow W in fig. 3. In this example, the winding direction W is the same as the rotational direction of the actuator, as indicated by arrow a in fig. 3. In principle, however, the winding direction W can also be opposite to the rotational drive direction a, so that the removal rate, i.e. the aggressiveness of the grinding tool 1, can be increased.

The partial bands 23, 24, 25 differ from one another in their abrasive properties. The first partial strip 23 extends at least approximately over the strip section of the grinding strip 13 forming the first layer L1. The backing 14 of the first partial band 23 is made of paper, here by way of example only, in order to achieve rapid deterioration of the first layer L1. Subsequent layers L2, L3 are formed from the second partial strip 24, wherein the backing 14 is made of woven fabric, by way of example only. Thus, the second partial strip 24 is more resistant and allows a higher removal rate than the first partial strip 23. Radially further inner layers L4 … L18 are formed by the third partial bands 25, the backing 14 of which is also made of fabric. Unlike the previous two partial bands 23, 24, the third partial band 25 has abrasive particles 18 of finer granularity to allow for fine grinding. In this way, the abrasive tool 1 initially allows for high removal rates at the beginning of the abrading process 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 abrasive tool 1 decreases and the abrasive pattern becomes finer and finer. In principle, however, the abrasive belt 13 may also have uniform abrasive properties along its entire length.

Furthermore, the grinding tool 1 has two stabilizing layers 26, 27, in particular annular, between which the grinding belt 13 and the carrier 5 are held. The stabilizing layers 26, 27 connect the abrasive belt 13 to the support body 5. In fig. 1, it can be seen that the stabilizing layers 26, 27 overlap, in particular completely overlap, the abrasive belt 13 and the support body 5 on both sides. The support section 39 thus has a multilayer structure. Each of the stabilizing layers 26, 27 is a self-contained, inherently stable layer that may degrade with the abrasive tape 13 during the abrading process. Furthermore, the stabilizing layers 26, 27 have aligned central holes for receiving the grommet 12, which extends through the stabilizing layers 26, 27 and the support body 5 embedded therebetween. The first stabilizing layer 26 closes with the first main tool side 2 of the abrasive tool 1 and the second stabilizing layer 27 closes with the second main tool side 3 of the abrasive tool. The stabilizing layers 26, 27 extend over the grinding section 6 and at least partially over the support body 5. The stabilizing layers 26, 27 each have a cured adhesive 28 into which reinforcing liners 29, 30, such as circular blanks of fabric material as shown in fig. 5 and 8, respectively, may be inserted or embedded.

The abrasive tape 13 is bonded to the stabilizing layers 26, 27 via an adhesive 28. Specifically, the abrasive belt 13 has an edge region 31, 32 at each axial end, the edge region having a circumferential edge 33, 34 that defines the abrasive belt 13. As a result of the winding of the abrasive belt 13, the respective circumferential edges 33, 34 follow a helical trajectory. As can be seen in fig. 10, gaps or spaces 35 may be formed between the various layers L1 … L18, although the layers L1 … L18 are preferably tightly packed together, this may occur primarily due to the roughened surface of the abrasive layer 16. During the manufacture of the abrasive tool 1, it can be pressed, whereby the adhesive 28, which remains flowable during the manufacturing process, penetrates partly into the spaces 35 from the stabilizing layers 26, 27 before it hardens there. The edge areas 31, 32 provided with the cured adhesive 28', 28″ each have an axial extension B31, B32 of less than 10% of the width B13 of the axial extension of the abrasive belt 13, respectively, 10% being only exemplary here. Advantageously, the remaining central grinding zone 20 extending between the two edge zones 31, 32 has an axial extension B20 corresponding to at least 80% of the width B13 of the grinding belt 13. In the grinding zone 20, the individual layers L1 … L18 of the grinding belt 13 are not connected to each other or loosely abut against each other. The thickness of the abrasive tool 1 corresponds to an axial extension A6 which is greater than the width B13 of the abrasive belt 13 by the thickness of the two stabilizing layers 26, 27. Their layer thickness is at most 2 mm, so that the adhesive 28', 28″ penetrating in the edge regions 31, 32 has no influence on the determination of the layer thickness.

Furthermore, the adhesive 28 may be arranged in a transition region 36, or may have penetrated and hardened during the pressing process when the grinding tool 1 is manufactured, the transition region 36 being formed between the radially innermost layer L18 of the support body 5 and the peripheral edge 9. As can be seen from fig. 1, the support body 5 can be arranged to engage with the profile geometry of the radially innermost layer L18, which profile geometry is open towards the rotation axis R. The outer diameter D5 of the support body can therefore be greater than the inner diameter D6 of the grinding section 6. In particular, the outer diameter D5 of the support body 5 may be 30 mm larger than the inner diameter D6 of the grinding section 6. The abrasive belt 13, in particular the radially innermost layer 19, thus surrounds the support body 5, in this case surrounds the support body 5 in a V-shape or receives the support body 5 in a V-shape. This radial engagement further increases the stability of the abrasive tool 1. In principle, however, the support body 5 can also end radially outside the abrasive belt 13 or at the radially innermost layer 19.

Fig. 4 to 9 show components of the abrasive tool 1, which may be provided before manufacturing the abrasive tool 1. In fig. 4, a label 37 is shown, which can be glued to the first main tool side 2. The tag 37 may indicate information about the abrasive tool 1 in a manner known per se. Fig. 5 shows a reinforcing liner 29 for the first stabilizing layer 26. The reinforcing liner 29 may be a circular blank made of a fabric material impregnated with the adhesive 28. Fig. 6 shows a raw material 38 in the form of a belt-like abrasive on a backing from which the profiled abrasive belt 13 can be made. The raw material 38 is spirally wound with the abrasive layer 16 directed radially outward. Fig. 7 shows two circular blanks 10, 11 made of a fabric material impregnated with adhesive, from which the support body 5 is made. Fig. 8 shows a reinforcing liner 30 for the second stabilizing layer 27, which may correspond to the reinforcing liner 29 shown in fig. 5. Figure 9 shows the grommet 12.

To manufacture the abrasive tool 1, the second reinforcing liner 30 may first be placed in a mold (not shown) having a cylindrical wall and a bottom. The coiled stock material 38 may then be positioned in a mold over the lower reinforcement liner 30. During this process, the radially outermost layer of raw material 38 rests against the cylindrical wall of the mold. Furthermore, the two fabric circular blanks 10, 11 are inserted into the center of the spirally wound stock material 38, and then the upper reinforcing liner 29 is placed on the wound stock material 38. Alternatively, the tag 37 may be placed on the upper reinforcing liner 29. In a further manufacturing process, a platen having an outer diameter corresponding to the inner diameter of the cylindrical wall of the mold is placed on the label 37 or on the upper reinforcing liner 29, and the components inserted into the mold for the abrasive tool 1 are pressed together under pressure and temperature acting along the rotation axis R to form the abrasive tool 1. During pressing, the wound main material 38 yields to compressive forces, whereby the raw material 38 can only flex towards the center due to the radially outer support provided by the die and the radially inner support provided by the circular blank of fabric 10, 11. In this process, the raw material 38 is buckled in a V shape in the radially inner layer, and the radially outermost layer L1 is buckled in particular in a U shape. The buckled raw material 38 forms the profiled abrasive tape 13. The peripheral edge 9 of the support body 5 is able and deformable due to the buckling of the raw material 38. To further influence the buckling of the raw material 38, the mold may have chamfers at the top and bottom edges of the cylindrical wall. Furthermore, the bottom of the mould may have a central bulge on which the circular blank of fabric 10, 11 for the support body 5 may be placed. During pressing, the adhesive 28 penetrates partly into the spaces 35 and the transition areas 36 and, in the cured state, thereby bonds the abrasive belt 13 to the support body 5.

In fig. 11, an abrasive tool 40 according to a second embodiment of the present invention is shown in a cross-sectional view with respect to the rotation axis R. The grinding tool 40 differs from the aforementioned grinding tool 1 according to the first embodiment as shown in fig. 1 to 10 only in that the grinding tool 40 is designed without a carrier. In this regard, reference is made to the above description regarding similar examples. The same or modified details are denoted by the same reference numerals. The grinding tool 40 may be a grinding sleeve with a grinding belt 13, the grinding belt 13 being wound around the rotation axis R in several layers L1 … L7, here only seven layers for example.

The radially inward second end 22 of the abrasive belt 13 terminates in an inner ring formed concentrically about the axis of rotation R, as shown in fig. 11. At the center of the abrasive tool 40, for example, a pin or spindle may be used to connect the abrasive tool 40 to a rotary drive machine.

In fig. 12, an abrasive tool 50 according to a third embodiment of the present invention is shown in a cross-sectional view with respect to the rotation axis R. The abrasive tool 50 is different from the foregoing abrasive tool 40 according to the second embodiment as shown in fig. 11 in that the winding of the abrasive tool 40 has a multilayer structure. In this regard, reference is made to the above description regarding similar examples. The same or modified details are denoted by the same reference numerals. In particular, the winding has eight layers formed by the abrasive belt 13 and seven further abrasive belts 51, here only an exemplary eight layers, which are wound together with the abrasive belt 13 in several layers L1, L2, here only an exemplary two layers, around the rotation axis R. The abrasive belts 13, 51 may have the same or different sanding characteristics. However, the abrasive belts may also have the same length or different lengths. The multi-layer windings shown herein in connection with abrasive tool 50 may be similarly applied to abrasive tool 1.

List of reference numerals

1. Part of the belt of the grinding tool 23

2. Main tool side 24 partial band

3. Main tool side 25 part belt

4. Circumferential side 26 stabilizer layer

5. Support 27 stabilization layer

6. Abrasive segment 28 binder

7. Body side 29 reinforced liner

8. Body side 30 reinforced liner

9. Peripheral edge 31 edge region

10. Edge region of circular blank 32

11. Circumferential edge of circular blank 33

12. Circumferential edge of the grommet 34

13. Space for adhesive 35

14. The backing 36 transition region

15. Tape side 37 label

16. Abrasive layer 38 raw material

17. Adhesive matrix 39 support section

18. Abrasive grain 40 grinding tool

19. Concave part of belt side 41

20. Grinding zone 50 grinding tool

21. Termination 51 adhesive

22. Termination of

A rotation driving direction L layer

B width, axial extension R axis of rotation

D diameter W winding direction

Claims

1. An abrasive tool (1; 40; 50) which can be driven in rotation about an axis of rotation (R), comprising:

-an abrasive belt (13) spirally wound with a plurality of superimposed layers (L) about the rotation axis (R) and having an abrasive layer (16) on a belt side (15) facing away from the rotation axis, characterized in that:

the wound grinding belt (13) is convexly curved with respect to the rotation axis (R) as seen in a longitudinal section along the rotation axis (R), and the layers (L) of the grinding belt (13) radially project into each other.

2. An abrasive tool (1; 40; 50) according to claim 1, characterized in that the radially inner layer (L2 … L18; L2 … L7; L2) of the abrasive belt (13) is axially partly covered by the adjacent radially outer layer (L1 … L17; L1 … L6; L1) of the abrasive belt (13) with respect to the rotation axis (R).

3. Abrasive tool (1; 40; 50) according to claim 1 or 2, characterized in that the profile geometry of the rolled abrasive belt (13) has a U-shape and/or V-shape at least partly along the belt length of the abrasive belt (13).

4. A grinding tool (1) according to any one of claims 1-3, characterized in that 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 (2), the grinding belt (13) being arranged axially between the first main tool side (2) and the second main tool side (3) with respect to the rotation axis (R).

5. Abrasive tool (1) according to claim 4, characterized in that the abrasive tool (3) is at least partially covered on its first main tool side (2) and/or second main tool side (3) by a respective stabilizing layer (26, 27), the abrasive belt (13) being fastened to the at least one stabilizing layer (26, 27).

6. Abrasive tool (1) according to claim 5, characterized in that the at least one stabilizing layer (26, 27) comprises an adhesive (28), wherein in an edge region (31, 32) of the abrasive belt (13) facing the respective stabilizing layer (26, 27), the adhesive (28) extends into an intermediate space (35) formed between the layers (L) of the abrasive belt (13).

7. Abrasive tool (1; 40; 50) according to any one of claims 1 to 6, characterized in that the layers (L) of the abrasive belt (13) are located one above the other in an unconnected manner at least in a central grinding region (20), which central grinding region (20) extends over at least 60% of the axial extension (B13) of the abrasive belt (13) with respect to the rotation axis (R).

8. The grinding tool (1) according to any one of claims 1 to 7, characterized in that the grinding tool (19) is a grinding disc and comprises a central support body (5), the grinding belt (13) being arranged around the support body (5).

9. Abrasive tool (1) according to claim 9 and any one of claims 5 to 7, characterized in that the abrasive belt (13) is fixed to the support body (5) by means of the at least one stabilizing layer (26, 27).

10. Abrasive tool (1) according to claim 8 or 9, characterized in that the support body (5) is plate-shaped and has a first body side (7) and a second body side (8) facing away from the first body side, and a peripheral edge (9) around which the abrasive belt (13) is arranged.

11. Abrasive tool (1) according to claim 10, characterized in that the first end (21) of the abrasive belt (13) ends at the outer periphery of the abrasive tool (1) and the second end (22) of the abrasive belt (13) ends at the outer peripheral edge (9) of the support body (5).

12. The grinding tool (50) according to any one of claims 1 to 11, characterized in that the grinding tool (50) has a multi-layer winding with the grinding belt (13) and at least one other grinding belt (51), the grinding belt (13) and the at least one other grinding belt (51) being wound at least partially in layers one above the other and in that a plurality of layers (L) are helically one above the other around the rotation axis (R).

13. A method of manufacturing an abrasive tool (1) according to any one of claims 1 to 12, the method comprising the steps of:

-providing a raw material (38) in the form of a belt-like abrasive;

-helically winding said raw material (38) around said rotation axis (R);

-arranging the wound raw material (38) in a mould having a cylindrical wall with an inner diameter at least approximately corresponding to the outer diameter of the grinding tool (1) to be produced; and

-pressing the wound raw material (38) in a direction along the rotation axis (R) until the raw material (38 a) flexes.