DE102023118042A1 - Grinding wheel unit for a side face grinding machine - Google Patents

Abstract

A grinding wheel unit (400) for use in a side face grinding machine comprises a base body (410) which defines a wheel rotation axis (402) and is or can be mounted on a tool spindle such that the wheel rotation axis (402) runs coaxially to the spindle axis; wherein the base body (410) has, in a peripheral region (412), a plurality of mounting regions (420) arranged offset from one another in the peripheral direction of the base body, with fastening devices for fastening a respective replaceable tool segment (500) to the base body (410). A tool segment (500) has a cutting means carrier (510) with mounting structures for fastening the cutting means carrier in one of the mounting regions, and a cutting coating (520) on a cutting coating side, which forms an abrasive effective surface of the tool segment. The abrasive active surfaces of the cutting coatings are arranged in a side surface of the grinding wheel unit oriented perpendicular to the wheel rotation axis within an annular active area (430) at a radial distance from the wheel rotation axis (402). At least one tool segment has a segmented cutting coating (520) on the cutting coating side of the cutting means carrier, which comprises at least two cutting material bodies arranged at a mutual distance from one another.

Description

FIELD OF APPLICATION AND STATE OF THE ART

The invention relates to a grinding wheel unit for use in a side face grinding machine and to a side face grinding machine equipped with at least one such grinding wheel unit.

The side face grinding machine can in particular be a double side face grinding machine. Double side face grinding machines can be used, for example, for grinding essentially plane-parallel, circular workpiece surfaces on a disk-shaped workpiece section of a workpiece. One possible area of application is the grinding of surfaces of a circular brake section of a brake disk, in particular a coated brake disk.

Upcoming tightening of the regulations on fine particle emissions from motor vehicles means that future brake discs for motor vehicles will have to be designed in such a way that fewer fine particles are released during braking. One approach to this is to coat the brake discs or their surface sections intended as friction surfaces with a thin functional layer made of more wear-resistant material. In a coated brake disc, the surfaces of the annular braking section each have a functional layer that is rotationally symmetrical with respect to the axis of rotation, the free surface of which is designed as the friction surface of the brake disc.

The manufacturing process of a coated brake disc includes one or more coating operations to coat the surfaces of the brake section of the brake disc with a functional layer that is intended to have a wear-reducing function due to its relatively high mechanical hardness. Alternatively or additionally, a corrosion-inhibiting effect can also be present. Such functional layers often consist essentially of metal; they can have a single layer or several layers with different properties. Such coatings can be applied, for example, by flame spraying or laser cladding. Typical layer thicknesses can be in the range between 50 µm and 350 µm. The coatings are usually applied on both sides. The documents EP 2 746 613 A2 and WO 2019/021161 A1 reveal examples of coated brake discs.

The carbides of the functional layers are generally mechanically relatively hard and the layers are relatively rough on the surface after coating. A subsequent grinding process is used to create a sufficiently flat surface on the coating that is optimized for the braking function. The specifications for friction surfaces of a brake disc can be such that the mean roughness Ra determined in accordance with DIN EN ISO 4288 should be in the range of 1 µm to 3 µm - 3.2 µm and the flatness deviation should be no more than 20 µm (cf. WO 2021/224308 A ).

Double-sided face grinding machines are often used for grinding brake discs.

The document DE 10 2021 132 468 B3 contains a detailed description of fine dust problems caused by braking and specific problems in the grinding of brake disks that have a coating that is difficult to machine. A device is described for grinding the flat sides of a coated brake disk for a motor vehicle, the device having at least two grinding disks, of which a first grinding disk is provided for pre-grinding the flat side by a large allowance and a second grinding disk is provided for finish-grinding the flat side by a small allowance. The two grinding disks are designed as cup disks that are axially displaceable relative to one another and lie one inside the other.

The document DE 20 2023 100 514 U1 describes, among other things, a double-sided surface grinding machine suitable for grinding brake disks on both sides, which comprises position data determination systems which determine, on the one hand, the axial position of the workpiece surface and, on the other hand, the axial position of the abrasive side surface of a grinding disk facing the workpiece surface in relation to the same reference coordinate system. A control unit of the grinding machine can control at least one grinding parameter in at least one phase of the grinding operation depending on the workpiece position data and/or the tool position data. This gives a user a tool for optimizing "his" grinding process. The grinding disks are designed as cup wheels segmented in the circumferential direction with individually replaceable and individually adjustable strip-shaped grinding segments.

The document EP 4 147 821 A1 discloses a device constructed in the manner of a double-side surface grinding machine for machining a hard-coated workpiece surface of a rotationally symmetrical workpiece comprising a workpiece drive device for generating a rotational movement about a workpiece rotation axis, at least one grinding wheel drive device for generating a rotational movement about a grinding wheel rotation axis, at least one feed device for bringing the grinding wheel into contact with the workpiece surface and at least one adjustment device for adjusting the grinding wheel rotation axis and the workpiece rotation axis to one another so that the grinding wheel rotation axis and the workpiece rotation axis are not parallel. The grinding wheels of the exemplary embodiment are shown as segmented cup wheels.

The inventors have recognized that when using conventional segmented cup wheels, particularly when grinding workpiece surfaces that are difficult to machine, signs of wear can occur relatively quickly, which make a tool change, i.e. a replacement of the tool segments, or at least a dressing process to dress the cutting surfaces and restore the original cutting properties necessary if one wants to avoid a deterioration in the grinding results due to wear. This impairs the productivity of the grinding process.

TASK AND SOLUTION

The invention is based on the object of providing a grinding wheel unit designed in the manner of a segmented cup wheel for use in a side face grinding machine, the use of which can increase the processing quality of the grinding process, particularly when grinding workpiece surfaces that are difficult to machine, without impairing productivity. Furthermore, a side face grinding machine equipped with at least one such grinding wheel unit is to be provided.

To solve this problem, the invention provides a grinding wheel unit with the features of claim 1. Furthermore, a side face grinding machine equipped with at least one such grinding wheel unit is provided. Advantageous further developments are specified in the dependent claims. The wording of all claims is made part of the content of the description by reference.

According to one aspect of the invention, a grinding wheel unit is provided for use in a side face grinding machine. The side face grinding machine has at least one tool spindle which can be driven in rotation about a spindle axis by means of a spindle drive. The term "grinding wheel unit" refers to a grinding wheel which is composed of several components or individual parts. The grinding wheel unit has a base body which defines a wheel rotation axis. The base body can be made from one piece or composed of several parts and preferably has a mass distribution which is essentially rotationally symmetrical to the wheel rotation axis. The grinding wheel unit is mounted on the tool spindle in such a way or can be mounted there in such a way that the wheel rotation axis runs coaxially to the spindle axis when the base body is mounted on the tool spindle.

The base body has several mounting areas in its peripheral area, arranged offset from one another in the peripheral direction of the base body, with devices for attaching a replaceable tool segment to the base body. A tool segment only extends over a fraction of the circumference of the grinding wheel unit, which can have many tool segments on its circumference. The number of these can be in the range of 10 to 20, for example, but can also be higher or lower.

A tool segment comprises a cutting medium carrier with mounting structures for fastening the cutting medium carrier or the tool segment in an assembly area and a cutting coating on a cutting coating side, which forms an abrasive effective surface of the tool segment. In a fully set-up state of the grinding wheel unit, the abrasive effective surfaces of the cutting coatings of the tool segments are essentially arranged in a common side surface of the grinding wheel unit oriented perpendicular to the wheel rotation axis within an annular effective area of the grinding wheel unit with a radial distance from the wheel rotation axis.

Such a grinding wheel unit can also be described as a circumferentially segmented cup grinding wheel with interchangeable tool segments.

This configuration offers the advantage that, for example, in the case of advanced wear of the cutting pads, the complete grinding wheel unit does not have to be removed from the tool spindle and replaced with a fresh one for a tool change. Instead, the base body can remain mounted on the tool spindle and only the tool segments are replaced. This concept is particularly advantageous for double-side surface grinding machines, as the replacement of complete grinding wheel units on is usually difficult and time-consuming due to the limited space available.

The cutting surfaces of the conventional grinding wheel units known to the inventors are formed by strip-shaped cutting material bodies of relatively narrow cutting strips. These extend essentially in the tangential direction of the grinding wheel unit, i.e. more or less perpendicular to the local radial direction in the middle of the assembly area. This makes it possible to achieve a relatively narrow effective area of the cup wheel in the radial direction with a high proportion of abrasive effective surfaces of the individual cutting material bodies.

According to the inventors' findings, the grinding results can be improved and the usable tool life increased if at least one tool segment on the cutting coating side of the cutting means carrier has a segmented cutting coating that comprises at least two cutting material bodies arranged at a distance from one another. This measure can be provided for one or more tool segments, preferably for all tool segments of the grinding wheel unit. This aspect is also referred to as "double segmentation" in the context of this application, and corresponding grinding wheel units as "double-segmented cup wheels". It has been shown that by segmenting the cutting coating of a tool unit, new degrees of freedom can be opened up for optimizing the grinding process and the grinding result.

Among other things, it was found that segmented grinding pads provide improvements in terms of cooling and flushing with coolant as well as in terms of wear reduction compared to conventional non-segmented grinding pads.

A segmented cutting coating can only comprise exactly two cutting material bodies. The segmented cutting coating preferably comprises three, four, five, six or more cutting material bodies. The number and design of the individual cutting material bodies can be adapted to the machining task within wide limits.

In preferred embodiments, the cutting material bodies each have a narrow effective surface which is delimited by two longitudinal edges running parallel or almost parallel to one another in the longitudinal direction of the cutting material body and transverse edges running transversely to the longitudinal edges, wherein a length of the effective surface measured parallel to at least one of the longitudinal edges between the transverse edges is several times greater than a width of the effective surface measured perpendicularly thereto. The length can, for example, be at least three times as large as the width; it is often advantageous if the aspect ratio between length and width is in the range of 3 to 6. Such narrow, e.g. rectangular, effective surfaces can be realized, for example, on strip-shaped or plate-shaped cutting material bodies.

This makes it possible to achieve relatively high surface pressures and correspondingly high cutting performance. At the same time, liquid machining aids, such as cooling lubricants or the like, can be introduced through the spaces between the cutting material bodies. This facilitates efficient cooling and also allows grinding residues to be easily removed.

Cutting material bodies can be arranged on the cutting surface side of the cutting means carrier in such a way that, when the tool segment is mounted, they are aligned in the tangential direction of the grinding wheel unit, i.e. essentially perpendicular to the radial direction. For example, two, three or more cutting material bodies arranged in a row at a distance from one another can be provided on a cutting surface side. It is also possible to arrange two or more rows of cutting material bodies with relatively narrow effective surfaces, offset from one another in the radial direction and running in the tangential direction.

Variants of tool segments with a segmented cutting coating have proven to be useful, among other things, when machining coated grinding wheels. These have at least one cutting material body which, when the tool segment is mounted, is oriented at an angle to the radial direction and at an angle to the circumferential direction in such a way that the effective surface within the annular effective area of the grinding wheel unit is neither tangential nor radial, but at an angle to these two directions. Preferably, two or more cutting material bodies arranged at a distance from one another and oriented at an angle are arranged on a tool segment, e.g. three, four, five, six or more.

The extent of the inclination can be optimized for the respective machining task. For many machining tasks, it has proven to be advantageous if the longitudinal direction of an obliquely oriented cutting material body forms an acute angle of no more than 45° with the radial direction of the grinding wheel unit. The acute angle can be in the range of 15° to 40°, for example, in particular around 30°. This allows the flushing using cooling lubricant to be further improved and a particularly good compromise between removal rate and wear can be achieved.

There are machining tasks in which the surface to be ground is sometimes difficult to access, for example when a hub section of a brake disk widens with increasing distance from the brake section. Among other things, embodiments are suitable for such cases which are characterized in that the base body has a circumferential surface which lies within a minimum enveloping circle coaxial with the disk rotation axis and that the cutting means carriers of the tool segments have a projection on the cutting lining side which is designed in such a way that when the tool segment is mounted, the cutting lining protrudes in the radial direction by an overflow width beyond the minimum enveloping circle. Then an annular effective surface of the grinding wheel unit defined by the effective surfaces of the cutting linings can have an outer radius which is larger than the radius of the base body. In other words, the cup wheel can widen radially towards the abrasive side surface.

Even when using tool segments with segmented cutting surfaces, tool changes are usually unavoidable. However, tool change times can be kept particularly short in embodiments in which an assembly area has a receiving device with stop surfaces for position-defined receiving of a tool segment and a quick-clamping device that can be switched between an open configuration and a clamping configuration, whereby in the open configuration a tool segment can be inserted into the receiving device or removed from the receiving device and in the clamping configuration the tool segment is pressed against the stop surfaces and can be fixed in a predetermined position on the base body. Preferably, it can be provided that the quick-clamping device can be switched between the open configuration and the clamping configuration by actuating a single actuating element. This means that unproductive downtimes caused by tool changes can be kept short. A quick-clamping device can, for example, be designed in the manner of a dovetail clamping device.

The invention also relates to a surface grinding machine comprising at least one grinding wheel unit of the type presented for the first time in this application.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 zeigt eine schematische Seitenansicht eines Ausführungsbeispiels einer Doppelseitenplanschleifmaschine, die zum Schleifen beschichteter Bremsscheiben eingerichtet ist und zwei segmentierte Topfscheiben gemäß einem Ausführungsbeispiel aufweist;
• 2 zeigt eine schrägperspektivische Ansicht einer Ausführungsform einer Schleifscheibeneinheit;
• 3 zeigt ein vergrößertes Detail der Schleifscheibeneinheit mit einer leeren Aufnahmeeinrichtung und Schnellspannsystem;
• 4 zeigt eine Baugruppe der Schwalbenschwanz-Spannvorrichtung mit einem keilförmigen Spannelement;
• 5 zeigt ein Werkzeugsegment mit schrägen Schneidleisten, die einen segmentierten Schneidbelag bilden;
• 6 zeigt eine Variante eines Werkzeugsegments mit einer Auskragung an der Schneidbelag-Seite des Schneidmittelträgers;
• 7 zeigt eine andere Variante eines Werkzeugsegments mit segmentiertem Schneidbelag.

Further advantages and aspects of the invention emerge from the claims and from the description of embodiments of the invention, which are explained below with reference to the figures.

• 1 shows a schematic side view of an embodiment of a double-side surface grinding machine which is designed for grinding coated brake discs and has two segmented cup wheels according to an embodiment;
• 2 shows an oblique perspective view of an embodiment of a grinding wheel unit;
• 3 shows an enlarged detail of the grinding wheel unit with an empty holder and quick-clamping system;
• 4 shows an assembly of the dovetail clamping device with a wedge-shaped clamping element;
• 5 shows a tool segment with inclined cutting bars that form a segmented cutting surface;
• 6 shows a variant of a tool segment with a projection on the cutting surface side of the cutting medium carrier;
• 7 shows another variant of a tool segment with segmented cutting surface.

DETAILED DESCRIPTION OF THE EMBODIMENTS

1 shows a schematic side view of an embodiment of a grinding machine 100, which is designed for grinding essentially plane-parallel, annular workpiece surfaces O1, O2 on a disk-shaped workpiece section of workpieces WS1, WS2 in the form of brake disks WS1, WS2. In the example case, the grinding machine is configured for grinding surfaces on both sides of an annular brake section BA of coated brake disks.

Each of the brake discs has a base body made of gray cast iron, for example, with a central hub section NA, which is used to attach the brake disc to a vehicle axle, and a circular brake section BA, which encloses the hub section. The mass distribution of the base body is overall rotationally symmetrical to the axis of rotation of the brake disc. The brake section has two axially opposite, parallel surfaces (upper workpiece surface O1 and lower workpiece surface O2).

These were tested in an upstream phase of the manufacturing process with a The coating or functional layer is rotationally symmetrical about the axis of rotation, the free surface of which is ultimately intended to serve as the friction surface of the brake disc. The coating can contain, for example, a stainless steel alloy with tungsten, titanium and/or silicon carbide and can be very hard. In the example, both sides were coated using a special variant of laser cladding, namely a variant of extreme high-speed laser cladding, which is also known as the "EHLA process". The coating can also be applied in other ways, e.g. by high-velocity flame spraying (HVOF) or cold gas spraying.

The grinding machine 100 is configured as a numerically controlled rotary transfer machine with two work stations, namely a loading station 110 for loading and unloading and a grinding station 120. All functions are implemented via control commands from a control unit 190 of the operating control system, which can be arranged locally (on or next to the machine) or remotely, e.g. in another room, and in the example case can be operated via a connected display and operating unit 195 with a graphical user interface.

To transport the brake discs between the work stations 110, 120, an internal machine transport system with a round table or rotary table 150 is used, which is mounted on or in the machine base 102 so that it can rotate about a vertical rotary table axis 152 and can be rotated indefinitely about the rotary table axis by means of a rotary drive 105.

At the 1 The loading station 110 is located on the left-hand side. There, a first brake disk (here WS1) is mounted on a workpiece spindle 154 in a horizontal orientation, i.e. with a vertically aligned axis of rotation (“turntable arrangement”). Loading can be carried out, for example, by means of a robot or another handling device, or manually. Fastening can be carried out, for example, by clamping it to a workpiece holding device or workpiece holder 155 of the workpiece spindle in such a way that the brake disk is clamped or mounted in a rotationally fixed manner and the axis of rotation of the brake disk is coaxial with the axis of rotation 156. A rotationally fixed connection to the workpiece spindle can also be achieved by holding it down or holding it from above. In the example, vertically movable hold-down devices 158 are provided.

A brake disc loaded in this way is then transported to a working position 125 in the area of the grinding station 120 by rotating the rotary table 180° clockwise. There, the work steps of the grinding operation (one or more) take place in a fully automated manner. In the loading station 110, a previously completely ground brake disc can be removed at the same time and a new, not yet ground one can be clamped in. After grinding has been completed, the brake disc, which has been completely ground on both sides, is transported to the loading station 110 by rotating it 180°, from where it can be unloaded, for example by means of a robot or another handling device, or manually. A new brake disc to be ground can be clamped onto the workpiece spindle that is then freed up, so that, with the exception of the changeover times, both workpiece spindles are occupied by brake discs and are each in different phases of handling.

The grinding machine processes the workpiece surfaces using the double-side face grinding method. At the grinding station 120, the grinding machine 100 has a grinding unit 121 with two tool spindles (upper tool spindle 132-1 and lower tool spindle 132-2) that are ideally arranged coaxially to one another on a frame part, each of which carries a grinding wheel (upper grinding wheel 130-2 and lower grinding wheel 130-2). The grinding wheels have abrasive side surfaces 135-1 and 135-2 facing one another and are arranged such that these grinding surfaces axially delimit a grinding space 133. Each of the grinding wheels can be rotated about the associated rotation axis 136-1 or 136-2 independently of the other grinding wheel by means of an associated spindle drive or rotation drive (upper rotation drive 134-1 or lower rotation drive 134-2) and can be fed or advanced parallel to the associated rotation axis with a predefinable feed speed profile by means of its own feed drive (upper feed drive 131-1 or lower feed drive 131-2).

The grinding machine 100 comprises a first position measuring system 200 equipped with pneumatic distance sensors S1-1 and S2-1 for determining workpiece position data that represent the axial position of a workpiece surface O1, O2 at at least one surface location in relation to a machine-fixed reference coordinate system RKS, and a second position measuring system 300 equipped with pneumatic distance sensors S1-2 and S2-2 for determining tool position data that represent the axial position of an abrasive side surface 135-1, 135-2 facing the workpiece surface O1, O2 in relation to the same reference coordinate system RKS. The control unit 190 can control at least one grinding parameter in at least one phase of the grinding operation depending on the workpiece position data and/or the tool position data. The sensors can be connected via integrated reference elements RE1, RE2-1 and RE2-2 can be calibrated if necessary. Details of these components and their function are e.g. in the DE 2020 23 100 514 U1 described, to whose disclosure reference is made in this respect.

The grinding wheels 130-1, 130-2 are designed as circumferentially segmented cup wheels with individually replaceable tool segments according to an embodiment of a grinding wheel unit described in this application.

The 2 shows an oblique perspective view of an embodiment of a grinding wheel unit 400, which can be used in the grinding machine described above as an upper grinding wheel 130-1 and/or as a lower grinding wheel 130-2. In the example case, both grinding wheels are constructed identically.

The grinding wheel unit 400 has a base body 410 which essentially has the shape of a flat, round disk which has a greater thickness in the outer peripheral section 412 than in the inner area enclosed by it. The mass distribution of the base body is rotationally symmetrical to the disk rotation axis 402 which, when the grinding wheel unit is mounted, runs coaxially to the spindle axis of the corresponding tool spindle. A central through-hole and further holes in the inner area of the base body are among the devices 411 with the aid of which the base body can be attached to the tool spindle with coaxial axes.

In the example, the base body has eighteen mounting areas 420 in its peripheral section 412, each of which covers a peripheral angle of 20° and has fastening devices for fastening a respective exchangeable tool segment 500 to the base body. The tool segments 500 are constructed identically to one another. 5 shows an enlarged view of a tool segment 500 of the 2 type depicted.

The tool segment 500 has a plate-shaped cutting medium carrier 510, which can be machined from solid material, for example, or manufactured using an additive manufacturing process. In the example, the cutting medium carrier is made of a steel material. In a segment coordinate system SKS, the length of the cutting medium carrier measured in the longitudinal direction L is several times greater than the width measured perpendicular to it in the width direction B; a ratio can be between 3:1 and 6:1, for example, and is approximately 5:1 in the example. The height measured in the height direction H is greater than the width and smaller than the length and corresponds to approximately three to five times the width.

The cutting means carrier 510 has a flat underside 512, an outer side 513 perpendicular thereto, an inner side 514 opposite thereto in the width direction and a cutting coating side 515 opposite the underside, on which the cutting means carrier carries a cutting coating (general reference numeral 520). The upper side of the cutting coating opposite the underside forms the abrasive active surface 525 of the tool segment 500.

The abrasive active surfaces of the individual tool segments lie more or less precisely in a common plane, which forms the side surface of the grinding wheel unit oriented perpendicular to the wheel rotation axis 402. Within this side surface, all abrasive active surfaces of the cutting coatings lie within an annular active area 430, the width of which measured in the radial direction R is only a fraction of the radial extent of the grinding wheel unit between the wheel rotation axis 402 and the outer edge, for example only 5% to 20% of this radial extent. When machining the workpiece, the grinding wheel unit only comes into material-removing contact with the workpiece surface to be ground with the grinding coatings of the active area 430. In this respect, this corresponds to the function of a conventional cup grinding wheel.

When the tool segments 500 are mounted in their respective associated mounting areas 420 on the circumference of the base body 410, the longitudinal direction L of the tool segments is oriented tangentially to the disk rotation axis 402, the width direction is approximately in the radial direction to the disk rotation axis and the height direction is parallel to it. The direction running parallel to the disk rotation axis is also referred to here as the axial direction.

One of the features of the grinding wheel unit 400 is that the individual tool segments can be mounted in the correct installation position on the base body in a very short time and can be removed just as quickly to be replaced by tool segments with fresh cutting pads if necessary. This enables a quick tool change without having to remove the base body from the tool spindle. After the tool change, the tool segments are then in a precisely predeterminable position on the base body, so that either subsequent joint dressing of the cutting pads can be dispensed with or any dressing can be completed in a short time. The special Construction or design of the base body in the respective assembly areas.

The design of an assembly area 420 is particularly good in 3 which shows, among other things, a side view of an assembly area without the tool segment to be mounted later. In the assembly area there is a receiving device 440 which is basically designed as a recess in the material of the peripheral section 412 of the base body 410, wherein its side surfaces, which are at an angle to one another, have a special structure and serve as stop surfaces for the position-defined reception of a tool segment 500. The recess in the base body is open to the outside in the radial direction R of the base body and forms a radial stop surface 442 for the facing side surface 514 of the cutting means carrier towards the disk rotation axis 402. The recess is open in the axial direction towards the side surface of the grinding wheel unit, but does not extend to the other side of the base body, but forms an axial stop surface 444 at a certain distance from the top of the base body, which is in contact with the underside 512 of the cutting medium carrier when the tool segment is installed.

The radial and axial stop surfaces are not designed as simple flat surfaces, but are offset several times, so that two webs are formed on each of the stop surfaces, which are spaced apart from one another, the free surfaces OB of which are each coplanar and have been machined with high mechanical precision, e.g. with a flatness in the range of 0.02 mm.

As in 3 As can be clearly seen from the tool segment used, the cutting medium carrier can be used in such a way that the underside 512 of the cutting medium carrier rests on the flat surfaces OB of the webs of the axial stop surface facing each other, with free space remaining in the area between the webs and to the sides of the webs. The situation is similar on the inward-facing radial support surface, where two webs with coplanar upper sides are also formed that are parallel to one another and serve as stop surfaces for the side surface of the cutting medium carrier.

With the help of these stop surfaces, it is possible to precisely specify the position of an inserted tool segment in both the axial and radial directions, so that subsequent adjustment work is not required in these directions. Accordingly, no complicated adjustment devices are required or provided.

The exact position definition in the circumferential direction is also obtained by contact with a stop surface, which is explained below in connection with the description of the quick-release device.

For the position-defined fastening of a tool segment to the base body, each of the assembly areas is equipped with a quick-clamping device 470, which is designed in the manner of a dovetail clamping device. The quick-clamping device acts essentially in the circumferential direction or tangential direction of the grinding wheel unit in such a way that the width of the holder device effective for the holder can be adjusted in the circumferential direction so that a larger width can be set for inserting and replacing a tool segment 500, which allows removal and insertion in the axial direction (open configuration), whereby the dovetail clamping device can also be converted into a closed clamping configuration by simple actuation, in which an inserted tool segment can be clamped with force components acting in the circumferential direction and thus fixed to the base body.

For this purpose, the recess of the receiving device 440 has a stop surface 446 acting in the circumferential direction, which is perpendicular to the axial stop surface and at an angle other than 90° to the radial stop surface. The inclined surface (stop surface 446) formed on the material of the base body serves as a fixed flank of the dovetail contour of the dovetail clamping device. The inclination is such that the inclined flank can be gripped behind in the radial direction.

The movable part of the dovetail clamping device is located on the opposite side in the circumferential direction. This comprises a wedge-shaped clamping element 460 (see 4 ), which widens from radially inside to outside in the assembled state, is supported with a side directed in the circumferential direction on a support surface of the base body lying in a radial plane and has a flat inclined surface 447 on the side opposite in the circumferential direction, which serves as an adjustable flank of the dovetail clamping device. The fixed flank 446 and the adjustable flank opposite in the circumferential direction together with the radial support surface form a dovetail groove which widens from radially outside to radially inside towards the radial contact surface 442.

The cutting medium carriers 510 of the tool segments 500 to be used have in the area of The end faces that are oriented obliquely to the tangential direction each have a corresponding bevel, so that the cutting medium carriers of the tool segments are not exactly cuboidal, but have a trapezoidal shape in section along the LB plane in such a way that they are wider on the inside than on the radial outside. If such a tool segment is inserted into the receiving device in the axial direction from above (or below) with the clamping device open, a positive locking effect is already in place even when the clamping device is open, such that the tool segment can no longer fall out in the radial direction.

The quick-clamping device 470, designed as a dovetail clamping device, can be easily switched between the open configuration (for inserting or removing a tool segment) and the clamping configuration (for securing an inserted tool segment) by actuating a single actuating element. It is just as easy to release the dovetail clamping device again in order to remove a tool segment. This functionality is used in connection with 4 This shows a clamping assembly 472 which is part of the dovetail clamping device and comprises the wedge-shaped clamping element 460, an actuating screw 462 and a counter-bearing element 464 which is cylindrical over a large part of its circumference. The counter-bearing element 464 is inserted into a cylindrical blind hole 465 at the edge of the mounting area in the base body and has a threaded hole perpendicular to the flattened side into which a threaded end section of the actuating screw 462 can be screwed.

The wedge-shaped clamping element 460 has a radially continuous bore with an internal thread section, into which an external thread section engages this actuating screw when the actuating screw 462 is inserted. One of the thread sections is a left-hand thread, the other thread section is a right-hand thread. This means that when the actuating screw 462 is turned in one direction (for example clockwise), the wedge-shaped clamping element is advanced in the direction of the counter-bearing element, while when the actuating screw is turned in the opposite direction, the radial distance between the counter-bearing element and the clamping wedge is necessarily increased, so that the clamping device can be released with the appropriate torque even if it has become stuck, for example if it has been in engagement with the tool segment for a long time.

A tool change, i.e. more precisely a change of the tool segments on the base body of the grinding wheel unit, is very easy to do using the following procedure. The starting point is a fully assembled grinding wheel unit whose grinding pads are worn after a long period of operation and therefore need to be replaced. To do this, the grinding wheel rotation is stopped and the tool segments are gradually removed. To release a tool segment from its corresponding holder, an operator or a robot only has to turn the actuating screw 462 of the wedge-shaped clamping element in the opening direction, which forces the clamping wedge to move outwards and thus opens the dovetail clamping device. The tool segment can then be removed and replaced with a fresh one. This can be firmly fixed in the holder by turning the actuating screw in the opposite direction and pressed against the stop surfaces acting axially, radially and in the circumferential direction. Such a tool change can be carried out quickly for all tool segments, so that tool change times can be reduced many times over compared to conventional solutions.

The grinding wheel unit or its tool segments are characterized by further special features which, independent of the special features which enable rapid tool segment changes, can also be provided in other generic grinding wheel units.

A special feature is that the tool segments 500 of the embodiment each have a segmented cutting coating on the cutting coating side 515 of the cutting means carrier 510. A segmented cutting coating in this sense has at least two cutting material bodies arranged at a mutual distance from one another. In the example, the tool segment 500 has five cutting material bodies 522 that are identical to one another, each with relatively narrow, rectangular active surfaces 525. Each of the cutting material bodies contains irregularly shaped cutting grains of different shapes and sizes that are bound within a bonding system. By selecting the type of cutting coating formed in this way, a grinding tool can be precisely adapted to the desired machining task. Cutting grains can be, for example, diamond grains or grains made of cubic boron nitride (CBN). Cutting grains can also consist of corundum and/or other types of ceramic materials, such as SiC. The bond can be made of a ceramic material or synthetic resin, for example. Metallic binding Bonding systems, such as galvanically produced bonds or sintered bonds, are possible, as are soldered bonds if necessary.

In the example case of 5 the abrasive cutting material bodies 522 are each attached to a metal sole 524 and together with the sole form a cutting bar 530. A cutting material body can be attached to the sole, for example, by sintering, soldering or gluing or by means of another adhesive layer. It is also possible for a cutting bar to consist entirely of a cutting material body, i.e. there is no stabilizing sole.

The cutting medium carrier 510 has a total of five receiving grooves 516 on its cutting surface side with a rectangular cross-section and a width that is dimensioned such that a cutting bar 530 can be inserted into a receiving groove with a precise fit and little lateral play and can be secured there, for example by gluing. The receiving grooves are arranged at equal distances from one another, with the distance measured in the width direction corresponding approximately to the width of the receiving grooves. In the example, a cutting bar 530 is inserted into each of the receiving grooves 516; in other embodiments, one or more receiving grooves remain free, so that, for example, only three cutting bars arranged at greater distances from one another can be accommodated. A cutting medium carrier can also have more or fewer receiving grooves; advantageously there should be at least three.

A special feature here is that the receiving grooves or the cutting strips accommodated therein are oriented at an angle to the longitudinal direction L of the cutting means carrier and also at an angle to the width direction B of the cutting means carrier. The acute angle SW between the width direction L of the cutting means carrier and the longitudinal direction LS of the cutting strips 530 is in the example case in the range of 20° to 40°, in particular around 30°. This means that the longitudinal directions LS of the cutting strips are oriented at an angle to the radial direction R of the grinding wheel unit when the tool segment is mounted on the base body, so that they are set at an angle of approximately 20° to 40° relative to the radial direction.

This oblique cutting arrangement has proven to be advantageous in numerous tests for several reasons compared to other orientations with cutting bars, which are also possible. For example, 7 an embodiment of a tool segment with a segmented cutting coating, which consists of three cutting strips 530 arranged in a row, which are oriented in the longitudinal direction of the cutting means carrier or, in the assembled state, in the tangential direction of the grinding wheel unit. In other variants, only two cutting strips arranged in a row are provided, e.g. with the dimensions 6x10x30 mm (WxHxL).

The tests have shown that segmented grinding pads, compared to conventional non-segmented grinding pads, offer improvements in terms of cooling and rinsing with coolant as well as in terms of wear reduction. The rectangular shape enables optimized production.

In addition to these advantages of segmented cutting surfaces, the inclined cutting means arrangement, which is exemplified in 5 shown, further advantages. Among other things, the flushing by means of cooling lubricant is further improved. This is attributed, among other things, to the fact that the inclined cutting bars 530 of the grinding wheel unit act similarly to inclined turbine blades when they rotate, so that the rotation of the grinding wheel forces the cooling lubricant to flow through the inclined spaces between the cutting bars in order to cool the cutting bars better on the one hand and to quickly remove abrasion on the other. This allows a further reduction in wear to be achieved.

It has also been found that the inclination can ensure a better distribution of the machining forces on the workpiece. While the effective area achieved in the radial direction is relatively narrow for cutting bars that are arranged essentially in the tangential direction of the cutting disk unit, the effective area of an inclined cutting bar of the same width is significantly wider due to the inclination, which leads to a better distribution of the load. This results in a wider cutting area in the radial direction, over which the force is introduced over a larger zone.

In addition, the total effective engagement surface for cutting bars of a given width is substantially larger in the case of several inclined cutting bars than in the case of tangential cutting bars of the same width. The inclined position of cutting bars also offers the possibility, in principle, of accommodating a relatively large number of particularly effective cutting bar front edges in the tangential direction. “Front edge” refers here to the longitudinal edge of a cutting bar 530 that leads in the direction of rotation of the grinding wheel unit and is the first to come into engagement with the workpiece to be machined. For example, a tool segment of the 5 The type shown has five leading cutting edges, each of which extends over a relatively large width in the radial direction (width direction).

In the previous tests, machining scenarios with synchronous and counter-rotating rotation as well as with different diameters of grinding wheel units and different angles of attack of the cutting bars were investigated. Under the boundary conditions investigated, inclinations in the order of approx. 30° ± 5° (as in the example of 5 ) has been found to be particularly advantageous. Deviations from this may also be advantageous under other machining conditions, but it appears that acute angles SW in relation to the radial direction of a grinding wheel unit should generally not be greater than 45°.

In the example cases of 5 and 6 all cutting material bodies are positioned at an angle to the radial direction and the tangential direction of the grinding wheel unit via the inclination angle. However, this is not mandatory. In an embodiment not shown, inclined cutting bars alternate with cutting bars oriented in the tangential direction, which are arranged near the outer circumference of the grinding wheel unit. This means that such a grinding wheel unit has a larger total effective area in the immediate vicinity of the radial edge than in the more internal area of the effective area of the segmented cup wheel defined by the cutting coatings. Such a variant can be advantageous if the machining situation only allows a small overflow of the grinding wheel unit over the area to be ground.

There are also machining tasks where the surface to be ground is difficult for the grinding wheel unit to access. For example, there are brake discs whose hub section widens starting from the level of the brake sections to be ground, so that the diameter of the hub section at the level of the brake sections is smaller than at an axial distance from it. The area of the brake section below the projection thus formed cannot be reached with conventional grinding wheel units, since the circumference of the grinding wheel unit would collide with the upper projection of the hub section when approaching the hub section, so that an inner zone of the brake section is not reached by the cutting bodies.

According to the inventors’ proposals, such problems can be solved with tool segments of the 6 shown. The tool segment 600 has a cutting means carrier 610 which has a greater width in the section on the cutting surface side than in the opposite end section near the underside. In other words, the cutting means carrier has a projection 612 towards the cutting surface side, so that the width BWW of the effective surface of the inclined cutting strips 630 (effective in the radial direction of the grinding wheel unit) is significantly greater here than the width BS of the cutting means carrier on its underside.

If such tool segments are attached to the base body of the grinding wheel unit, this has an external effective area on the abrasive side surface that extends further outwards in the radial direction, so that the outer radius of the effective area is larger than the outer radius of the base body. In other words, the effective area formed by the inclined cutting strips can extend beyond the imaginary axial extension of the cylindrical outer contour of the base body. This also makes it possible to reach the radially inner zone of the braking section for grinding without the grinding wheel unit colliding with the hub section of the braking disc.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 2 746 613 A2 [0004]
• WO 2019/021161 A1 [0004]
• WO 2021/224308 A [0005]
• DE 10 2021 132 468 B3 [0007]
• DE 20 2023 100 514 U1 [0008, 0039]
• EP 4 147 821 A1 [0009]

Claims (13)

Grinding wheel unit (400) for use in a side face grinding machine (100), which has at least one tool spindle (132-1, 132-2) which can be driven in rotation about a spindle axis (136-1, 136-2) by means of a spindle drive (134-1, 134-2), comprising: a base body (410) which defines a wheel rotation axis (402) and can be or is mounted on the tool spindle (136-1, 136-2) in such a way that the wheel rotation axis (402) runs coaxially to the spindle axis; wherein the base body (410) has, in a circumferential region (412), a plurality of mounting regions (420) arranged offset from one another in the circumferential direction of the base body, with fastening devices for fastening a respective exchangeable tool segment (500, 600) to the base body (410); wherein a tool segment (500, 600) has a cutting means carrier (510) with mounting structures for fastening the cutting means carrier in one of the mounting areas and a cutting coating (520) on a cutting coating side (515), which forms an abrasive active surface of the tool segment, wherein the abrasive active surfaces of the cutting coatings are arranged in a side surface (135-1, 135-2) of the grinding wheel unit oriented perpendicular to the wheel rotation axis within an annular active region (430) at a radial distance from the wheel rotation axis (402); characterized in that at least one tool segment has a segmented cutting coating (520) on the cutting coating side (515) of the cutting means carrier (510), which comprises at least two cutting material bodies (522) arranged at a mutual distance from one another. grinding wheel unit after claim 1 , characterized in that the cutting coating (520) has three, four, five, six or more cutting material bodies (522). grinding wheel unit after claim 1 or 2 , characterized in that the cutting material bodies (522) each have a narrow active surface (525) which is delimited by two longitudinal edges running parallel (or almost parallel) to one another in the longitudinal direction of the cutting material body and transverse edges running transversely to the longitudinal edges, wherein a length LW of the active surface measured parallel to the longitudinal edges between the transverse edges is several times greater than a width BW of the active surface measured perpendicular to the longitudinal edges, wherein preferably an aspect ratio between the length LW and the width BW is at least 3:1 and/or is in the range from 3:1 to 6:1. Grinding wheel unit according to one of the preceding claims, characterized in that a tool segment (500, 600) has at least one cutting material body (525) which, in the assembled state of the tool segment, is oriented obliquely to the radial direction (R) and obliquely to the tangential direction (T) of the grinding wheel unit (400) in such a way that the longitudinal direction of the effective surface within the annular effective area (430) of the grinding wheel unit is neither tangential nor radial, but obliquely to these two directions, grinding wheel unit after claim 4 , characterized in that a tool segment (500, 600) has two or more cutting material bodies (525) arranged at a mutual distance from one another, which, in the assembled state of the tool segment, are oriented obliquely to the radial direction and obliquely to the tangential direction of the grinding wheel unit. grinding wheel unit after claim 4 or 5 , characterized in that a longitudinal direction (LS) of an obliquely oriented cutting material body (522) encloses an acute angle (SW) of a maximum of 45° with a radial direction (R) of the grinding wheel unit, wherein the angle is preferably in the range from 15° to 40°, in particular approximately 30°. Grinding wheel unit according to one of the preceding claims, characterized in that the base body has a circumferential surface which lies within a minimum enveloping circle coaxial with the wheel rotation axis and that the cutting means carriers of the tool segments have a projection (612) on the cutting coating side such that when the tool segment is mounted, the cutting coating projects in the radial direction by an overflow width beyond the minimum enveloping circle, wherein preferably an annular effective surface of the grinding wheel unit defined by the effective surfaces of the cutting coatings has an outer radius which is larger than the radius of the base body. Grinding wheel unit according to one of the preceding claims, characterized in that a mounting area (420) has a receiving device (440) with stop surfaces (442, 444) for positionally defined receiving of a tool segment (500, 600) and a quick-clamping device (470) which can be switched between an open configuration and a clamping configuration, wherein in the open configuration a tool segment (500, 600) can be inserted into the receiving device device (440) or can be removed from the receiving device and, in the clamping configuration, the tool segment is pressed against the stop surfaces and can be fixed in a predetermined position on the base body (410). grinding wheel unit after claim 8 , characterized in that the quick-clamping device (470) can be switched between the open configuration and the clamping configuration by actuating a single actuating element (462). grinding wheel unit after claim 8 or 9 , characterized in that a receiving device (440) comprises a recess in the base body (410), wherein the recess is open to the outside in the radial direction (R) and has at least one radial stop surface (442) in the opposite direction and is open towards the side surface in the axial direction and has at least one axial stop surface (444) in the opposite direction, wherein preferably in the region of a radial stop surface (442) and/or in the region of an axial stop surface (444) on the surfaces delimiting the recess, two or more webs offset from one another in the circumferential direction with recessed sections in between are provided, wherein the upper sides (OB) of the webs serving as stop surfaces are manufactured with high precision. Grinding wheel unit according to one of the Claims 8 until 10 , characterized in that the quick-clamping device (470) is designed in the manner of a dovetail clamping device, wherein preferably a dovetail contour is oriented such that an insertion and removal of the tool segment (500, 600) from the dovetail clamping device can be carried out in a direction parallel to the disk rotation axis (402), wherein preferably the dovetail clamping device (470) has a fixed dovetail flank and an adjustable dovetail flank lying opposite in the circumferential direction and the dovetail flanks delimit a dovetail groove which has a radially inner groove bottom surface and narrows radially outwards. Grinding wheel unit according to one of the Claims 8 until 11 , characterized in that the quick-clamping device (470) has a wedge-shaped clamping element (460) which can be moved in the radial direction (R) via an actuating screw (462), preferably aligned in the radial direction, wherein preferably at least one of the following features is realized: i) a wedge surface of the wedge-shaped clamping element forms a movable flank of an associated dovetail clamping device (470), ii) the wedge-shaped clamping element can be moved both radially inwards and radially outwards by means of the actuating screw (462), iii) the actuating screw (462) has a section with a right-hand thread and a section with a left-hand thread. Side face grinding machine (100) for grinding a substantially flat workpiece surface on a workpiece section (WA) of a workpiece (WS1, WS2), in particular a double-side face grinding machine for grinding workpiece surfaces of a circular brake section of a brake disk, comprising a grinding unit (121) with at least one tool spindle (132-1, 132-2) which carries a grinding disk (130-1, 130-2) with an abrasive side surface (135-1, 135-2), wherein the grinding disk can be rotated about the associated rotation axis (136-1, 136-2) by means of an associated rotation drive (134-1, 134-2) and can be fed parallel to the associated rotation axis by means of an infeed drive (131-1, 131-2), at least one workpiece spindle (154) with a workpiece holder (155) for rotationally fixedly holding the workpiece (WS1, WS2), wherein the workpiece holder is rotatable by means of a rotary drive (157) about a rotation axis (156) running parallel or obliquely to the rotation axis of the grinding wheel and is arranged in a working position at least during a phase of a grinding operation such that the workpiece section (WA) of the received workpiece comes into contact with the abrasive side surface, characterized in that the grinding wheel is designed as a grinding wheel unit (400) according to one of the preceding claims.

Images