Grinding disc unit for lateral surface grinding machine

Abstract

The present invention relates to a grinding disc unit (400) for use in a lateral surface grinding machine, the grinding disc unit (400) comprising a main portion (410) that defines a disc rotation axis (402) and is attached to or can be attached to a tool spindle such that the disc rotation axis (402) extends coaxially with the spindle axis, the circumferential region (412) of the main portion (410) having a plurality of mounting regions (420), the plurality of mounting regions being offset from each other in the circumferential direction of the main portion and comprising fixing devices for fixing each interchangeable tool segment (500) to the main portion (410). The tool segment (500) comprises a cutting means support (510) having a cutting means support having a mounting structure for fixing the cutting means support to one of the mounting regions, and a cutting tool (520) on the side surface of the cutting tool, the cutting tool forming the grinding functional surface of the tool segment. The polishing functional surface of the cutting tool is positioned on a lateral plane of the grinding disc unit, and the lateral plane is oriented perpendicular to the disc rotation axis within an annular functional region (430) at a predetermined radial distance with respect to the disc rotation axis (402). At least one tool segment has a segmented cutting tool (520) on the cutting tool side surface of the cutting means support, and the segmented cutting tool comprises at least two cutting material bodies spaced apart from each other.

Description

Technical Field

[0001] The present invention relates to a grinding disk unit used in a side surface grinding machine, and also to a side surface grinding machine provided with at least one such grinding disk unit.

Background Art

[0002] A double-sided surface grinding machine can be used, for example, to grind substantially parallel planar circular workpiece surfaces on a disk-shaped workpiece portion of a workpiece. One applicable field is the grinding of the circular brake portion of a brake disk, particularly the coated brake disk surface.

[0003] With the strengthening of regulations regarding the emission of particulate matter from automobiles, it has been suggested that future automotive brake disks need to be designed such that less particulate matter is emitted during braking. One approach to this is to coat the brake disk or the surface portion thereof provided as a friction surface with a thin functional layer made of a material with higher wear resistance. In a coated brake disk, each surface of the circular brake portion supports a rotationally symmetric functional layer with respect to the axis of rotation, and its free surface is designed as the friction surface of the brake disk.

[0004] The manufacturing process for coated brake discs includes one or more coating steps for coating the surface of the brake portion of the brake disc with a functional layer, which needs to have a wear-reducing function due to its relatively high mechanical hardness. Alternatively or additionally, it may have a corrosion-resistant effect. Often, such a functional layer is substantially composed of metal and may consist of a single layer or multiple layers having different properties. Such coatings can be applied, for example, by thermal spraying or laser cladding. Typical layer thicknesses can be, for example, in the range of 50 μm to 350 μm. The coating is generally applied to both sides. Examples of coated brake discs are disclosed in European Publication No. 2746613 and International Publication No. 2019 / 021161.

[0005] The carbides in the functional layer are generally mechanically relatively hard, and the surface of the coated layer is relatively rough. Subsequent grinding processes are intended to give the coating a sufficiently flat surface optimized for braking function. For example, the specifications for the friction surface of a brake disc are such that the central roughness Ra, measured according to DIN EN ISO 4288, is in the range of 1 μm to 3 μm-3.2 μm, and the flatness deviation does not exceed 20 μm (see International Publication No. 2021 / 224308).

[0006] In most cases, a double-sided surface grinder is used to grind brake discs.

[0007] German Patent No. 102021132468 provides a detailed description of the problem of fine dust generated by braking and specific problems when grinding brake discs with coatings that are difficult to machine. The document describes an apparatus for grinding the flat surface of a coated brake disc for automobiles, the apparatus having at least two grinding discs, the first of which is provided for extensive pre-grinding of the flat surface, and the second grinding disc is provided for slight finish grinding of the flat surface. The two grinding discs are designed as cup discs, where one is positioned within the other, and are displaceable relative to each other in the axial direction.

[0008] German Utility Model Publication No. 202023100514 describes a double-sided surface grinder, particularly suitable for grinding both sides of brake discs, which includes a position data determination system that first determines the axial position of the workpiece surface and then determines the axial position of the polishing outer surface of the grinding disc facing the workpiece surface, relative to the same reference coordinate system. The grinding machine's control unit can control at least one grinding parameter in at least one stage of the grinding operation, according to the workpiece position data and / or tool position data. This provides the user with assistance in optimizing their own grinding process. The grinding disc is designed as a cup disc having circumferentially segmented, individually replaceable, and individually adjustable strip-shaped grinding segments.

[0009] European Publication No. 4147821 discloses, in particular, an apparatus for machining a hard-coated workpiece surface of a rotationally symmetric workpiece, which is configured in the form of a double-sided surface grinder and comprises: a workpiece drive for generating rotational motion around a workpiece rotation axis; at least one grinding disc drive for generating rotational motion around a grinding disc rotation axis; at least one feed device for bringing the grinding disc into contact with the workpiece surface; and at least one setting device for setting the grinding disc rotation axis and the workpiece rotation axis relative to each other so that the grinding disc rotation axis and the workpiece rotation axis are not parallel. The grinding disc in an exemplary embodiment is shown as a segmented cup disc.

[0010] The inventors have found that, particularly when grinding the surface of a workpiece that is difficult to machine, using conventional segmented cup discs results in relatively rapid wear. Therefore, to avoid deterioration due to wear resulting from grinding, it is necessary to replace the tool, i.e., replace the tool segment, or at least perform a dressing process to restore the original cutting properties by dressing the cutting layer. This negatively impacts the productivity of the grinding process. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] European Publication No. 2746613 [Patent Document 2] International Publication No. 2019 / 021161 [Patent Document 3] German patent no. 102021132468 [Patent Document 4] German Patent Application Publication No. 202023100514 [Patent Document 5] European Publication No. 4147821 [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] The problem that the present invention aims to solve is to provide a grinding disc unit designed in the form of a segmented cup disc for use in a side surface grinding machine, which, by using this grinding disc unit, can improve the machining quality of the grinding process, especially when grinding the surface of a workpiece that is difficult to machine, without adversely affecting productivity. Furthermore, a side surface grinding machine equipped with at least one such grinding disc unit is provided. [Means for solving the problem]

[0013] To solve this problem, the present invention provides a grinding disc unit having the features of claim 1. Furthermore, a lateral surface grinding machine comprising at least one such grinding disc unit is provided. Advantageous developments are specified in the dependent claims. All claim language is incorporated herein by reference.

[0014] One aspect of the present invention provides a replaceable tool segment for use in a grinding disc unit for use in a lateral surface grinder. The lateral surface grinder has at least one tool spindle, which can be rotationally driven around a spindle axis by a spindle drive. The term “grinding disc unit” refers to a grinding disc composed of multiple components or individual parts. The grinding disc unit has a body that defines the axis of rotation of the disc. The body may be manufactured as a single piece or composed of multiple parts, and preferably has a mass distribution that is substantially rotationally symmetric with respect to the axis of rotation of the disc. The grinding disc unit is mounted or can be mounted on a tool spindle such that when the body is mounted on the tool spindle, the axis of rotation of the disc extends coaxially with the spindle axis.

[0015] The main body has a plurality of mounting areas in its periphery, offset from each other in the circumferential direction of the main body, and in each case, having devices for fastening interchangeable tool segments to the main body. The periphery is an area extending inward from the radially outer circumferential surface of the main body over a predetermined radial width. The radial width of the periphery is, for example, in the range of 5% to 20% of the radius of the main body. The tool segments extend only over a portion of the periphery of the grinding disc unit, and this grinding disc unit may have a large number of tool segments over its periphery. The number of tool segments can be, for example, in the range of 10 to 20, but may be more or fewer.

[0016] The tool segment comprises a cutting means support and a cutting layer, the cutting layer having a cutting means support or a mounting structure for fastening the tool segment to a mounting area, the cutting layer forming the effective grinding surface of the tool segment on the side surface of the cutting layer. In the fully set up state of the grinding disc unit, the effective grinding surface of the cutting layer of the tool segment is substantially located on a common side surface of the grinding disc unit oriented perpendicular to the disk rotation axis, within an annular effective area of ​​the grinding disc unit at a predetermined radial distance from the disk rotation axis. The annular effective area can be relatively narrow with respect to the radius or half diameter of the body. The annular effective area can have a width, for example, ranging from 2% to 20%, more specifically from 2% to 10%, of the radius or half diameter of the body when measured radially.

[0017] Such a grinding disc unit can also be described as a cup grinding disc that is segmented in the circumferential direction and has replaceable tool segments.

[0018] This configuration has the advantage of eliminating the need to remove the entire grinding disc unit from the tool spindle and replace it with a new one, for example, when the cutting layer wears down and the tool needs replacing. Instead, only the tool segment can be replaced while the main body remains attached to the tool spindle. This concept is particularly advantageous for double-sided surface grinders, as replacing the entire grinding disc unit is generally difficult and time-consuming due to limited installation space.

[0019] The cutting layer of conventional grinding disc units recognized by the inventors is formed by strip-shaped cutting material bodies of relatively narrow cutting strips. These extend substantially tangentially to the grinding disc unit, that is, approximately perpendicular to the local radial direction in the center of the mounting area. As a result, the effective area of ​​the cup disc, which is relatively narrow in the radial direction, can be achieved with a high proportion of the effective polishing surface of the individual cutting material bodies.

[0020] Our findings indicate that grinding results are improved and usable tool life is extended when at least one tool segment has a segmented cutting layer on the side surface of the cutting layer of a cutting means support, and this segmented cutting layer comprises at least two cutting material bodies spaced apart from each other. This approach can be applied to one or more tool segments, preferably all tool segments of a grinding disc unit. This embodiment is also referred to as “double segmentation” within the scope of this application, and the corresponding grinding disc unit is referred to as “double segmented cup disc.” It has been found that segmenting the cutting layer of a tool unit creates new degrees of freedom for optimizing the grinding process and grinding results.

[0021] In particular, segmented cutting layers have been shown to provide improvements in cooling and flushing by coolant lubricants, as well as in wear reduction, compared to conventional non-segmented cutting layers.

[0022] The segmented cutting layer can simply comprise exactly two cutting material bodies. The segmented cutting layer preferably comprises 3, 4, 5, 6 or more cutting material bodies. The number and configuration of the individual cutting material bodies can be adapted to the machining task within a wide range.

[0023] In a preferred embodiment, each of the cutting material bodies has a narrow effective surface defined by two longitudinal edges extending parallel or substantially parallel to each other in the longitudinal direction of the cutting material body and a transverse edge extending transversely to the longitudinal edges, and the length of the effective surface measured parallel to at least one of the longitudinal edges between the transverse edges is several times larger than the width of the effective surface measured perpendicular to the length. The length can be, for example, at least 3 times as large as the width, and the aspect ratio between the length and the width is often conveniently in the range from 3 to 6. Such a narrow, for example rectangular, effective surface can be implemented on, for example, a strip-shaped or plate-shaped cutting material body. As a result, a relatively high surface pressure and the corresponding high machining capacity can be achieved. At the same time, liquid machining aids, such as cooling lubricants, etc., can be introduced through the gaps between the cutting material bodies. This facilitates efficient cooling and also easily discharges grinding residues.

[0024] The cutting material bodies can be arranged on the cutting layer side surface of the cutting means support, and when the tool segments are attached, the cutting material bodies are oriented substantially perpendicular to the tangential direction of the grinding disk unit, that is, to the radial direction. For example, 2, 3 or more cutting material bodies arranged in a row at intervals in the longitudinal direction of each other can be provided on the cutting layer side surface. It is also possible to arrange two or more rows of cutting material bodies offset from each other in the radial direction, extending in the tangential direction and having a relatively narrow effective surface.

[0025] In particular, a modification of the tool segment having segmented cutting layers has been found to be effective for machining coated grinding discs, in which there is at least one cutting material body, which is oriented obliquely to the radial direction and obliquely to the circumferential direction, and with the tool segment attached, the effective surface is not oriented tangentially or radially, but rather obliquely to these two directions within the annular effective area of ​​the grinding disc unit. Two or more obliquely oriented cutting material bodies, e.g., 3, 4, 5, 6 or more, arranged at a distance from each other, are preferably arranged on one tool segment.

[0026] The degree of inclination can be optimized for each machining task. For many machining tasks, it has been found advantageous for the longitudinal direction of the obliquely oriented cutting material body to include an acute angle of up to 45° with respect to the radial direction of the grinding disc unit. The acute angle can range, for example, from 15° to 40°, specifically around 30°. As a result, flushing with the cooling lubricant is further improved, achieving a particularly good compromise between removal performance and wear.

[0027] For example, there are machining tasks where accessing the surface to be ground is difficult, such as when the hub portion of a brake disc widens as the distance from the brake portion increases. A particularly suitable embodiment for such cases is characterized in that the body has a circumferential surface within a minimum envelope coaxial with the disc rotation axis, and the cutting means support portion of the tool segment has a projection on the side surface of the cutting layer, such that when the tool segment is mounted, the cutting layer protrudes radially beyond the minimum envelope by an overrun width. The annular effective surface of the grinding disc unit (defined by the effective surface of the cutting layer) can have an outer radius larger than the radius of the body. In other words, the cup disc can widen radially toward the grinding side surface.

[0028] Even when using tool segments with segmented cutting layers, tool changes are usually unavoidable. However, tool change time can be particularly shortened in embodiments where the mounting area has a receiving device with a stop surface for receiving the tool segment in place, and a quick-action clamping device that can be switched between an open configuration and a clamped configuration. In this case, in the open configuration, the tool segment can be inserted into or removed from the receiving device, and in the clamped configuration, the tool segment can be pressed against the stop surface and fixed in place on the body. Preferably, the quick-action clamping device can be switched between the open configuration and the clamped configuration by acting on a single actuation element. This means that unproductive downtime due to tool changes can be reduced. The quick-action clamping device can be designed, for example, in the form of a dovetail clamping device.

[0029] Furthermore, the present invention relates to a surface grinding machine comprising at least one grinding disc unit of the type first presented in this application.

[0030] Further advantages and aspects of the present invention will become apparent from the description of exemplary embodiments of the present invention, which will be described below with reference to the claims and drawings. [Brief explanation of the drawing]

[0031] [Figure 1] A schematic side view is shown of an exemplary embodiment of a double-sided surface grinder, designed for grinding coated brake discs and having two segmented cup discs according to one exemplary embodiment. [Figure 2] A perspective view of one embodiment of the grinding disc unit is shown. [Figure 3] This shows a detailed enlarged view of a grinding disc unit equipped with an empty receiving device and a quick-action clamping system. [Figure 4] This shows an assembly of a dovetail-type clamping device equipped with a wedge-shaped clamping element. [Figure 5] This shows a tool segment having an oblique cutting strip that forms a segmented cutting layer. [Figure 6] A modified example of a tool segment having a protrusion on the side surface of the cutting layer of a cutting means support is shown. [Figure 7] Another variation of a tool segment having a segmented cutting layer is shown. [Modes for carrying out the invention]

[0032] Figure 1 shows a schematic side view of an exemplary embodiment of a grinding machine 100 designed to grind substantially parallel-plane circular workpiece surfaces O1, O2 on the disc-shaped workpiece portions of brake discs WS1, WS2. In this embodiment, the grinding machine is configured to grind the surface of the circular brake portion BA of a brake disc that is coated on both sides.

[0033] Each brake disc has a body made of, for example, gray cast iron, and comprises a central hub portion NA that serves to fix the brake disc to the axle, and a circular brake portion BA that surrounds the hub portion. The mass distribution of the body as a whole is rotationally symmetric with respect to the axis of rotation of the brake disc. The brake portion has two parallel surfaces (upper workpiece surface O1 and lower workpiece surface O2) that are opposite each other in the axial direction.

[0034] In the upstream stages of the manufacturing process, these surfaces are fitted with a coating or functional layer that is rotationally symmetric with respect to the axis of rotation, and the free surface of this coating or functional layer is intended to ultimately function as the friction surface of the brake disc. The coating may be very hard and may include, for example, a stainless steel alloy containing tungsten, titanium, and / or silicon carbide. In embodiments, both surfaces are coated using a special variant of laser cladding, specifically a variant of ultrafast laser cladding also known as the "EHLA process." The coating may also be applied by other methods, such as high-velocity thermal spraying (HVOF) or cold gas spraying.

[0035] The grinding machine 100 is configured as a numerically controlled rotary indexing machine comprising two workstations, specifically a loading station 110 for loading and unloading, and a grinding station 120. All functions are performed by control commands of a control unit 190 of the operation control system, which can be located locally (on or next to the machine) or remotely, for example, in another room, and in the embodiment, can be operated via an operation unit 195 equipped with a connected display and a graphical user interface.

[0036] The brake discs are transported between workstations 110 and 120 using an internal machine transport system equipped with a rotary table or turntable 150, the rotary table or turntable 150 being mounted on or within a machine base 102 so as to be rotatable around a vertical turntable axis 152, and capable of rotating indefinitely around the turntable axis using a rotary drive unit 105.

[0037] The supply station 110 is located on the left side in Figure 1. There, the first brake disc (here WS1) is supported on a workpiece spindle 154 in a horizontal orientation, i.e., with its rotation axis oriented vertically (record player configuration). Loading can be done, for example, by a robot or other handling device, or manually. Fastening can be done, for example, by clamping the brake disc in a predetermined position, or clamping it in a rotationally fixed state, and clamping it in a predetermined position on the workpiece holding device or workpiece receiving portion 155 of the workpiece spindle so that the rotation axis of the brake disc is coaxial with the rotation axis 156. Rotationally fixed coupling to the workpiece spindle can also be performed by pressing or holding from above. In the embodiment, a vertically displaceable pressing means 158 is provided.

[0038] The brake discs, thus brought in, are then transported to a working position 125 within the area of ​​the grinding station 120 by rotating the rotary table 180° clockwise. The grinding process's work steps (one or more) are then controlled entirely automatically. At the supply station 110, the already fully ground brake discs can be simultaneously removed, and new brake discs that have not yet been ground can be clamped. Once grinding is complete, the brake discs, both fully ground, are rotated 180° and transported to the supply station 110, from where they can be unloaded, for example, by a robot or other handling device, or manually. The new brake discs to be ground can then be clamped onto the now-empty workpiece spindle, so that, except for the changeover time, both workpiece spindles are occupied by brake discs, each in a different handling stage.

[0039] The grinding machine machines the surface of a workpiece by a double-sided surface grinding process. In the grinding station 120, the grinding machine 100 has a grinding unit 121 comprising two tool spindles (an upper tool spindle 132-1 and a lower tool spindle 132-2, respectively), which are ideally arranged coaxially with each other on a frame portion, and each supports a grinding disc (an upper grinding disc 130-2 and a lower grinding disc 130-2, respectively). The grinding discs each have opposing abrasive sides 135-1 and 135-2, which are arranged to define a grinding space 133 in the axial direction. Each grinding disc can be rotated independently of other grinding discs around an associated rotating shaft 136-1 or 136-2 by an associated spindle drive or rotary drive (upper rotary drive 134-1 or lower rotary drive 134-2), and can also be fed or advanced parallel to the associated rotating shaft at a specified feed rate profile by an independent feed drive (upper feed drive 131-1 or lower feed drive 131-2).

[0040] The grinding machine 100 includes a first position measuring system 200 equipped with pneumatic distance sensors S1-1 and S2-1 for determining workpiece position data representing the axial positions of workpiece surfaces O1 and O2 at at least one surface position, relative to a reference coordinate system RKS of the machine base, and a second position measuring system 300 equipped with pneumatic distance sensors S1-2 and S2-2 for determining tool position data representing the axial positions of grinding sides 135-1 and 135-2 facing the workpiece surfaces O1 and O2, relative to the same reference coordinate system RKS. The control unit 190 can control at least one grinding parameter in at least one stage of the grinding process according to the workpiece position data and / or tool position data. The sensors can be calibrated by integrated reference elements RE1, RE2-1 and RE2-2 as needed. Details of these components and their functions are described, for example, in German Patent Publication No. 2020 23 100 514, and in this regard, the disclosures in this document are referred to.

[0041] The grinding discs 130-1 and 130-2 are designed as cup discs that are circumferentially segmented and have individually replaceable tool segments, according to the embodiment of the grinding disc unit described in this application.

[0042] Figure 2 is a perspective view of an embodiment of a grinding disc unit 400 that can be used as the upper grinding disc 130-1 and / or lower grinding disc 130-2 in the grinding machine described above. In this example, both grinding discs have the same configuration.

[0043] The grinding disc unit 400 has a body 410 having a substantially flat circular disc shape, the body 410 having a greater thickness in its outer peripheral portion 412 than the internal region surrounded by this outer peripheral portion. This peripheral portion or peripheral region is a region extending inward from the radially outer peripheral surface 413 of the body with a predetermined radial width. The radial width of the peripheral region can be, for example, less than 10% of the semidiameter of the body.

[0044] The mass distribution of the main body is rotationally symmetric with respect to the disk rotation axis 402, which extends coaxially with the spindle axis of the corresponding tool spindle when the grinding disc unit is mounted. The central through hole and further holes 411 in the internal region of the main body belong to the apparatus, and these holes allow the main body to be fixed to the tool spindle on a coaxial axis.

[0045] In this embodiment, the main body has 18 mounting areas 420 around its perimeter 412, each mounting area occupying a 20° perimeter angle area and in each case having a fastening device for fastening a replaceable tool segment 500 to the main body. The tool segments 500 are identical in configuration to each other. Figure 5 shows an enlarged view of a tool segment 500 of the type shown in Figure 2.

[0046] The tool segment 500 has a plate-shaped cutting means support 510, which can be manufactured, for example, by machining from a solid material by removing material or by an additive manufacturing process. In this embodiment, the cutting means support is made of steel. In the segment coordinate system SKS, the length of the cutting means support, measured in the longitudinal direction L, is several times greater than the width, measured perpendicular to the length in the width direction B, with the ratio being, for example, between 2:1 and 6:1, and approximately 5:1 in this embodiment. The height, measured in the height direction H, is greater than the width and less than the length, and is approximately 3 to 5 times the width.

[0047] The cutting means support 510 has a flat bottom side surface 512, an outer side surface 513 perpendicular to the bottom side surface, an inner side surface 514 located opposite the outer side surface in the width direction, and a cutting layer side surface 515 located opposite the bottom side surface, on which the cutting means support supports the cutting layer (overall reference numeral 520). The upper side surface of the cutting layer located opposite the bottom side surface forms the effective polishing surface 525 of the tool segment 500.

[0048] The effective grinding surfaces of individual tool segments are precisely located, to varying degrees, within a common plane forming the side surface of the grinding disc unit, which is oriented perpendicular to the disc rotation axis 402. Within this side surface, all effective grinding surfaces of the cutting layer are within the annular effective region 430, and the width measured in its radial direction R is only a portion of the radial range of the grinding disc unit between the disc rotation axis 402 and the outer edge, for example, 5% to 20% of this radial range. During machining of the workpiece, the grinding disc unit makes material removal contact with the workpiece surface being ground only by the grinding layer of the effective region 430. In this respect, this corresponds to the function of a conventional cup grinding disc.

[0049] The annular effective region 430 is relatively narrow with respect to the radius or half diameter of the body 410. In the embodiment, the annular effective region is measured radially and has a width in the range of 2% to 10% of the radius or half diameter of the body.

[0050] Furthermore, Figure 2 clearly shows that the annular effective region 430 protrudes radially outward beyond the circumferential surface 413 of the main body 410. Therefore, the annular effective region 430 extends outward beyond the circumferential surface of the main body. In other words, since the annular effective region 430 has an outer radius larger than the radius or half diameter of the main body, a radial projection 414 is generated. The projection 414 can be, for example, 1% or more, 2% or more, or 5% or more of the radius of the main body.

[0051] When the tool segments 500 are mounted in their respective associated mounting areas 420 around the main body 410, the longitudinal direction L of each tool segment is oriented tangentially with respect to the disk rotation axis 402, the width direction is approximately radial with respect to the disk rotation axis, and the height direction is parallel thereto. The direction extending parallel to the disk rotation axis is also referred to here as the axial direction.

[0052] The grinding disc unit 400 is particularly characterized by the fact that individual tool segments can be mounted to the main body in the correct mounting position in a very short time, and can be removed just as quickly to replace them with tool segments having a new cutting layer, if necessary. This allows for quick tool changes without removing the main body from the tool spindle. After the tool is replaced, the tool segment is positioned in a precisely defined position on the main body, so that subsequent joint dressing of the cutting layer can be omitted or some dressing can be performed in a short time. This is achieved by the specific structure or configuration of the main body in each mounting area.

[0053] The configuration of the mounting area 420 is shown particularly clearly in Figure 3, which specifically shows a side view of the mounting area, and does not show the tool segment to be mounted therein later. The mounting area contains a receiving device 440, which is basically designed as a recess in the material of the peripheral portion 412 of the main body 410, and the sides of this receiving device, which are angled relative to each other, have a specific structure and function as a stopper surface for receiving the tool segment 500 in a specified position. The recess in the main body opens outward in the radial direction R of the main body and forms a radial stopper surface 442 of the opposing side 514 of the cutting means support relative to the disk rotation axis 402. The recess opens axially to the side of the grinding disk unit but does not penetrate to the other side of the main body, but rather forms an axial stopper surface 444 at a certain distance from the top surface of the main body, which contacts the bottom side 512 of the cutting means support when the tool segment is mounted.

[0054] The radial and axial stopper surfaces are not designed as simple flat surfaces, but rather are offset several times, so that two webs are formed on each stopper surface, spaced apart from each other, and the free surfaces OB of each of these webs lie on the same plane and are machined with high mechanical precision, for example, to a flatness in the range of 0.02 mm.

[0055] As can be clearly seen from Figure 3 with the tool segment inserted, the cutting means support can be inserted such that the bottom side surface 512 of the cutting means support rests on the flat surfaces OB of the opposing webs, which are axial stopper surfaces, and there is still space between the webs and on the sides of the webs. The inwardly facing radial support surface also forms two mutually parallel webs having a corresponding appearance and coplanar upper sides, the upper sides of which function as stopper surfaces on the sides of the cutting means support.

[0056] These stopper surfaces allow for precise positioning of the inserted tool segment in both the axial and radial directions, eliminating the need for subsequent adjustments in these directions. Consequently, complex adjustment devices are unnecessary and do not need to be provided.

[0057] Precise positioning in the circumferential direction can also be achieved by contacting the stopper surface, which will be further explained below in conjunction with the description of the quick-action clamping device.

[0058] To fasten the tool segment to the main body in a defined position, each mounting area is equipped with a quick-action clamping device 470 designed as a dovetail clamping device. The quick-action clamping device acts substantially in the circumferential or tangential direction of the grinding disc unit so that the effective receiving width of the receiving device can be adjusted in the circumferential direction, allowing for a wider width to be set for the insertion and replacement of the tool segment 500, thereby enabling axial removal and insertion (open state). On the other hand, the dovetail clamping device can also be switched to a closed clamping state with a simple operation, in which case the inserted tool segment is clamped by a force component acting in the circumferential direction and as a result fixed to the main body.

[0059] For this purpose, the recess of the receiving device 440 has a stopper surface 446 that acts in the circumferential direction, is perpendicular to the axial stopper surface, and is at an angle different from 90° with respect to the radial stopper surface. The inclined surface (stopper surface 446) formed in the material of the main body functions as a fixing flank of the dovetail groove contour of the dovetail clamp device. This inclination is such that it can engage behind the inclined flank in the radial direction.

[0060] The movable part of the dovetail clamp device is located on the opposite side in the circumferential direction. This movable part comprises a wedge-shaped clamp element 460 (see Figure 4), which, in the mounted state, extends radially inward to outward and is supported by its circumferentially oriented side surface on the support surface of the main body located in the radial plane, and has a flat inclined surface 447 on the opposite side in the circumferential direction that functions as an adjustable flank of the dovetail clamp device. The fixed flank 446 and the adjustable flank located on the opposite side in the circumferential direction, together with the radial support surface, form a dovetail groove, which extends radially outward to radially inward, i.e., toward the radial contact surface 442.

[0061] Each cutting means support 510 of the inserted tool segment 500 has a corresponding bevel in the region of the end face oriented obliquely to the tangential direction, so the cutting means support of the tool segment is not exactly a cube, but rather has a trapezoidal shape in cross-section along the LB plane, being wider inward than outward in the radial direction. When the clamping device is open, if this type of tool segment is inserted into the receiving device axially from above (or below), an interlocking coupling is immediately established so that the tool segment can no longer move radially even if the clamping device is open.

[0062] The quick-action clamping device 470, configured as a dovetail clamping device, can be easily switched between an open configuration (for inserting or removing tool segments) and a clamped configuration (for securing inserted tool segments) by acting on a single actuation element. It is equally easy to release the dovetail clamping device again to remove a tool segment. This functionality is illustrated with particular reference to Figure 4, which shows a clamp assembly 472, part of the dovetail clamping device, comprising a wedge-shaped clamping element 460, an actuation screw 462, and a cylindrical fitting support element 464 extending over most of its periphery. The fitting support element 464 is inserted into a cylindrical blind hole 465 at the end of the mounting area of ​​the main body, and has a screw hole perpendicular to its flat side, allowing the threaded end of the actuation screw 462 to be screwed into the screw hole.

[0063] The wedge-shaped clamping element 460 has a radially penetrating hole and a female thread that engages with the male thread of the operating screw 462 when the operating screw is inserted. One thread is left-hand thread and the other is right-hand thread. As a result, when the operating screw 462 is rotated in one direction (e.g. clockwise), the wedge-shaped clamping element is moved toward the mating support element, and when the operating screw is rotated in the opposite direction, the radial distance between the mating support element and the clamp wedge is necessarily increased. Consequently, even if the clamping device is stuck, such as after being engaged with a tool segment for a long time, it can be released with appropriate torque.

[0064] Replacing the tool, or more precisely, replacing the tool segment on the body of the grinding disc unit, is very easy and can be done by following these steps. The starting point is a fully mounted grinding disc unit where the grinding layer has worn down due to relatively long-term use and needs to be replaced. Therefore, the rotation of the grinding disc is stopped and the tool segment is removed in stages. To release the tool segment from the corresponding receiving device, an operator or robot simply needs to rotate the operating screw 462 of the wedge-shaped clamping element in the release direction. As a result, the clamping wedge will inevitably move outward, and the dovetail-shaped clamping device will be released. The tool segment can then be removed and replaced with a new one. This tool segment can be securely fixed back into the receiving device by rotating the operating screw in the opposite direction and can be pressed against stopper surfaces acting in the axial, radial, and circumferential directions. Such tool replacement can be performed quickly for all tool segments, and therefore the tool replacement time can be significantly reduced compared to conventional solutions.

[0065] The grinding disc unit or its tool segment may be further characterized by specific features, which may be provided independently of any other grinding disc unit of the same type that allows for the rapid replacement of the tool segment.

[0066] One distinctive feature is that each of the tool segments 500 in the exemplary embodiment has a segmented cutting layer on the cutting layer side surface 515 of the cutting means support 510. The segmented cutting layer in this sense has at least two cutting material bodies arranged at a distance from each other. In this embodiment, each of the tool segments 500 has five identical cutting material bodies 522 having a relatively narrow rectangular effective surface 525. Each cutting material body contains irregularly shaped cutting particles of different shapes and sizes bonded within a bonding system. By selecting the type of cutting layer thus formed, the grinding tool can be precisely adapted to a desired machining task. The cutting particles can be, for example, diamond particles or particles made of cubic boron nitride (CBN). The cutting particles may also consist of corundum and / or other types of ceramic materials such as SiC. The binder can consist of, for example, ceramic material or synthetic resin. Metallic bonding systems, such as galvanized bonding or sintered bonding, are also possible, as is solder bonding.

[0067] In the embodiment shown in Figure 5, each of the abrasive cutting material bodies 522 is fixed onto a metallic sole 524, forming a cutting strip 530 together with the sole. The cutting material bodies can be fixed onto the sole, for example, by sintering, soldering, adhesive bonding, or by another adhesive layer. It is also possible for the cutting strip to consist only of the cutting material bodies, i.e., without a stabilizing sole.

[0068] The cutting means support 510 has a total of five rectangular receiving grooves 516 on its cutting layer side, the width of which is such that a cutting strip 530 can be inserted into the receiving groove with precision fitting and little lateral play, and can be fixed there, for example, by adhesive bonding. The receiving grooves are spaced uniformly apart from each other, and the distance measured in the width direction is approximately corresponding to the width of the receiving groove. In this embodiment, a cutting strip 530 is inserted into each of the receiving grooves 516, but in other embodiments, one or more receiving grooves are left empty to accept, for example, only three cutting strips spaced further apart from each other. The cutting means support may also have more or fewer receiving grooves, and advantageously, there should be at least three receiving grooves.

[0069] One distinctive feature here is that the receiving groove or the cutting strip to be received therein is oriented obliquely with respect to the longitudinal direction L of the cutting means support and obliquely with respect to the width direction B of the cutting means support. The acute angle SW between the width direction L of the cutting means support and the longitudinal direction LS of the cutting strip 530 is in the range of 20° to 40° in the embodiment, more specifically about 30°. This means that the longitudinal direction LS of the cutting strip having a tool segment attached to the body is oriented obliquely with respect to the radial direction R of the grinding disc unit so that it is set to approximately 20° to 40° with respect to the radial direction.

[0070] This oblique cutting arrangement has proven advantageous in many tests for several reasons, although these other orientations are also possible. For example, Figure 7 shows an embodiment of a tool segment having a segmented cutting layer, which consists of three cutting strips 530 arranged in a row relative to each other and oriented in the longitudinal direction of the cutting support, or, in the mounted state, in the tangential direction of the grinding disc unit. In other modifications, for example, only two cutting strips arranged in a row, with dimensions of 6x10x30mm (BxHxL), are provided.

[0071] Tests have shown that segmented grinding layers offer improvements over conventional non-segmented grinding layers, particularly in terms of cooling and flushing by cooling lubricants and reduced wear. The rectangular shape allows for manufacturing optimization.

[0072] In addition to the advantages of these segmented cutting layers, the oblique arrangement of the cutting means, as illustrated in Figure 5, offers further advantages. In particular, flushing by the cooling lubricant is further improved. This is due in particular to the fact that when the inclined cutting strips 530 of the grinding disc unit rotate, they act similarly to inclined turbine blades, and the rotation of the grinding disc causes the cooling lubricant to flow through the inclined intermediate space between the cutting strips, firstly cooling the cutting strips more effectively and secondly carrying away wear dust more quickly. Thus, a further reduction in wear is achieved.

[0073] Furthermore, it has been found that inclination can ensure good distribution of machining forces on the workpiece. With a cutting strip positioned substantially tangentially to the cutting disc unit, the effective area achieved radially is relatively narrow, but with an inclined cutting strip of the same width, the effective area is considerably wider due to the inclination, thereby improving load distribution. As a result, the radial cutting area is widened, and force is introduced over a larger area.

[0074] In addition, the overall effective engagement surface for a cutting strip of a particular width is substantially larger for multiple inclined cutting strips than for a tangential cutting strip of the same width. In principle, the inclination of the cutting strip also provides the possibility of fitting a relatively large number of particularly abrasive leading edges of the cutting strip when viewed from the tangential direction. Here, “leading edge” refers to the leading edge in the rotational direction of the grinding disc unit and the longitudinal edge of the cutting strip 530 that first engages with the workpiece being machined. Thus, the type of tool segment shown in Figure 5 has five leading edges of cutting bodies, each extending over a relatively large width in the radial direction (width direction).

[0075] In previous tests, machining scenarios with co-rotation and counter-rotation, as well as grinding disc units of different diameters and different cutting strip entry angles, were investigated. Under the investigated boundary conditions, an inclination of approximately 30° ± 5° (example in Figure 5) was found to be particularly suitable. While deviations from this may be favorable under other machining conditions, the acute angle SW of the grinding disc unit with respect to the radial direction should generally not exceed 45°.

[0076] In the embodiments shown in Figures 5 and 6, all cutting material bodies are set obliquely to the radial and tangential directions of the grinding disc unit via an inclination angle. However, this is not mandatory. In embodiments not shown, the inclined cutting strips are alternated with cutting strips oriented tangentially and positioned close to the outer circumference of the grinding disc unit. Such grinding disc units near the radial edge thus have a total effective surface area larger than the further internal area of ​​the effective surface of the segmented cup disc defined by the cutting layer. Such modifications can be advantageous when machining conditions allow only a slight overrun on the area being ground by the grinding disc unit.

[0077] Some machining tasks involve surfaces that are difficult for grinding disc units to access. For example, there are brake discs where the hub portion extends from the level of the brake portion being ground, and the diameter of the hub portion at the brake portion level is smaller than the diameter at a position further axially away from it. In conventional grinding disc units, the area of ​​the brake portion below the resulting protrusion cannot be reached because the outer circumference of the grinding disc unit collides with the upper protrusion of the hub portion when approaching the hub portion, meaning that the inner area of ​​the brake portion is not reached by the cutting body.

[0078] According to our proposal, this type of problem can be solved by a tool segment of the type shown in Figure 6. The tool segment 600 has a cutting means support 610, which has a greater width in the portion on the cutting layer side than in the portion on the opposite end near the bottom side. In other words, the cutting means support has a projection 612 toward the cutting layer side, and the width BWW of the effective surface of the inclined cutting strip 630 (which is effective in the radial direction of the grinding disc unit) is considerably larger here than the width BS of the cutting means support at its bottom side.

[0079] When such tool segments are attached to the body of a grinding disc unit, the grinding disc unit consequently has an outer effective area on the grinding side, and this outer effective area extends further outward in the radial direction, so that the outer radius of the effective area is greater than the outer radius of the body. In other words, the effective area formed by the inclined cutting strip can extend beyond the intended axial extension of the cylindrical outer shape of the body. As a result, the grinding disc unit can reach the radially inward area of ​​the brake portion for grinding without colliding with the hub portion of the brake disc. [Explanation of Symbols]

[0080] 135-1, 135-2 Side view of the grinding disc unit 136-1, 136-2 Tool Spindle 402 Disk rotation axis 410 Main Unit 412 Surrounding area 420 mounting area 430 Annular effective region 500, 600 tool segments 510 Cutting means support 512 Bottom side 513 Exterior side 514 Internal side 515 Cutting layer side surface 520 cutting layer L Longitudinal direction B Width direction H (height direction)

Claims

1. A grinding disc unit (400) for use in a lateral surface grinding machine (100) having at least one tool spindle (132-1, 132-2) and which can be rotationally driven around a spindle axis (136-1, 136-2) by a spindle drive unit (134-1, 134-2), A disk rotation axis (402) is defined, and a body (410) is provided which is attachable to or attached to the tool spindle (136-1, 136-2) such that the disk rotation axis (402) extends coaxially with the spindle axis. The main body (410) has a plurality of mounting areas (420) in a peripheral region (412) located radially outward, and the plurality of mounting areas are offset from each other in the circumferential direction of the main body, and in each case has a fastening device for fastening replaceable tool segments (500, 600) to the main body (410). The tool segment (500, 600) is a cutting means support (510) having a mounting structure for fixing the cutting means support (510) to one of the mounting areas, and a cutting layer (520) on the cutting layer side surface (515), the cutting layer forming the effective polishing surface of the tool segment. On the side surfaces (135-1, 135-2) of the grinding disc unit oriented perpendicular to the disc rotation axis, the effective polishing surface of the cutting layer is positioned within a radially outer annular effective region (430) at a predetermined radial distance from the disc rotation axis (402), thereby the grinding disc unit is designed in the form of a cup disc segmented in the circumferential direction. A grinding disc unit in which at least one tool segment has a segmented cutting layer (520) on the side surface (515) of the cutting layer of the cutting means support (510), and the segmented cutting layer comprises at least two cutting material bodies (522) arranged at a distance from each other.

2. The grinding disc unit according to claim 1, wherein the cutting layer (520) has 3, 4, 5, 6 or more cutting material bodies (522).

3. Each of the cutting material bodies (522) has a narrow, particularly rectangular, effective surface (525) defined by two longitudinal edges extending parallel or substantially parallel to each other in the longitudinal direction of the cutting material body and a transverse edge extending laterally with respect to the longitudinal edges, wherein the length LW of the effective surface measured parallel to the longitudinal edges between the transverse edges is several times greater than the width BW of the effective surface measured perpendicular to the longitudinal edges, and the aspect ratio between the length LW and the width BW is preferably at least 3:1 and / or in the range of 3:1 to 6:1, the grinding disc unit according to claim 1 or 2.

4. The grinding disc unit according to any one of claims 1 to 3, wherein the tool segment (500, 600) has at least one cutting material body (525), the cutting material body being oriented obliquely to the radial (R) and tangential directions of the grinding disc unit (400) when the tool segment is attached, and the longitudinal direction of the effective surface is not oriented to either the tangential or radial direction, but rather oblique to these two directions within the annular effective region (430) of the grinding disc unit.

5. The grinding disc unit according to claim 4, wherein the tool segments (500, 600) have two or more cutting material bodies (525), the cutting material bodies are arranged at a distance from each other, and are oriented obliquely to the radial and tangential directions of the grinding disc unit when the tool segments are mounted.

6. The grinding disc unit according to claim 4 or 5, wherein the longitudinal direction (LS) of the obliquely oriented cutting material body (522) includes an acute angle (SW) of up to 45° with respect to the radial direction (R) of the grinding disc unit, and the angle is preferably in the range of 15° to 40°, particularly about 30°.

7. The grinding disc unit according to any one of claims 1 to 6, wherein the main body has a circumferential surface located within the minimum circumscribed circle coaxial with the disk rotation axis, the cutting means support portion of the tool segment has a projection on the side surface of the cutting layer such that, when the tool segment is attached, the cutting layer protrudes radially beyond the minimum circumscribed circle by an overrun width, and the annular effective surface of the grinding disc unit, defined by the effective surface of the cutting layer, preferably has an outer radius larger than the radius of the main body.

8. The grinding disc unit according to any one of claims 1 to 7, wherein the mounting area (420) has a receiving device (440) having stopper surfaces (442, 444) for receiving the tool segments (500, 600) in predetermined positions, and has a quick-action clamping device (470) that can be switched between an open configuration and a clamped configuration, the tool segments (500, 600) can be inserted into or removed from the receiving device (440) in the open configuration, and the tool segments can be pressed against the stopper surfaces and fixed in predetermined positions on the main body (410) in the clamped configuration.

9. The grinding disc unit according to claim 8, wherein the quick-action clamping device (470) can be switched between the open configuration and the clamped configuration by operating a single actuation element (462).

10. The receiving device (440) is provided with a recess in the main body (410), the recess opening outward in the radial direction (R) and having at least one radial stopper surface (442) in the opposite direction, and the recess opening sideways in the axial direction and having at least one axial stopper surface (444) in the opposite direction. The grinding disc unit according to claim 8 or 9, wherein two or more webs, offset from one another in the circumferential direction and having intermediate recesses, are preferably provided in the region of the radial stopper surface (442) and / or the region of the axial stopper surface (444) on the surface that defines the recesses, and the upper surface (OB) of the webs that function as stopper surfaces is manufactured with high precision.

11. The quick-action clamping device is designed in the form of a dovetail clamping device, and preferably the dovetail groove contour is oriented so that the tool segments (500, 600) can be inserted into and removed from the dovetail clamping device in a direction parallel to the disk rotation axis (402). The dovetail clamp device (470) preferably has a fixed dovetail flank and an adjustable dovetail flank located on opposite sides in the circumferential direction, wherein the dovetail flank has a groove bottom surface radially inward and defines a dovetail groove that narrows radially outward, according to any one of claims 8 to 10.

12. The quick-action clamping device (470) preferably has a wedge-shaped clamping element (460) that is movable in the radial direction (R) via an operating screw (462) which is preferably oriented radially, i) The wedge surface of the wedge-shaped clamping element forms a movable flank of the associated dovetail clamping device (470). ii) The wedge-shaped clamping element can be moved radially inward and radially outward by the operating screw (462), iii) The operating screw (462) has a right-hand thread portion and a left-hand thread portion, A grinding disc unit according to any one of claims 8 to 11, wherein at least one of the following features is implemented.

13. The number of the tool segments (500, 600) is in the range of 10 to 20; The annular effective region (430) has a width measured in the radial direction (R) and is 2% to 20% of the radial range of the grinding disk unit between the disk rotation axis (402) and the outer edge of the grinding disk unit; The annular effective region (430) has a width measured in the radial direction (R) that is 2% to 20% of the radius of the body; The grinding disc unit has an outer effective region on its polishing surface, and the outer effective region extends radially outward such that the outer radius of the effective region is greater than the outer radius of the main body. A grinding disc unit according to any one of claims 1 to 12, characterized by at least one of the features of the above.

14. A lateral surface grinder (100) for grinding a substantially flat workpiece surface on a workpiece portion (WA) of a workpiece (WS1, WS2), and a double-sided surface grinder for grinding the workpiece surface of a circular brake portion of a brake disc, A grinding unit (121) having at least one tool spindle (132-1, 132-2), supporting a grinding disc (130-1, 130-2) having abrasive surfaces (135-1, 135-2), wherein the grinding disc can be rotated around an assigned rotation axis (136-1, 136-2) by associated rotational drive devices (134-1, 134-2), and can be fed parallel to the associated rotation axis by feed devices (131-1, 131-2), At least one workpiece spindle (154) having a workpiece receiving portion (155) for receiving the workpieces (WS1, WS2) in a rotatably fixed manner, wherein the workpiece receiving portion is rotatable by a rotary drive device (157) around a rotation axis (156) extending parallel or obliquely to the rotation axis of the grinding disc, and is positioned in a working position during at least one stage of the grinding operation such that the workpiece portion (WA) of the received workpiece is in contact with the grinding surface, Equipped with, A grinding machine in which the grinding disc is designed as a grinding disc unit (400) according to any one of claims 1 to 13.

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