EP3439825B1 - Changing station and method for the automatic changing of abrasives - Google Patents

Description

TECHNICAL AREA

The present invention relates to a changing station which enables a robot-assisted grinding device to automatically change grinding media (e.g. grinding wheels).

BACKGROUND

Grinding machines such as orbital grinding machines are widely used in industry and craft. Orbital grinding machines are grinding machines in which an oscillating movement (vibration) is superimposed on a rotary movement about an axis of rotation. They are often used for finishing surfaces with high surface quality requirements. So that these requirements can be met, irregularities should be avoided as much as possible during the grinding process. In practice, this usually happens because these tasks are carried out by experienced skilled workers, especially in the production of small quantities.

In the case of robot-supported grinding devices, a grinding tool (for example an orbital grinding machine) is guided by a manipulator, for example an industrial robot. The grinding tool can be coupled to the so-called TCP ( Tool Center Point ) of the manipulator in different ways, so that the manipulator can set the position and orientation of the tool practically as desired. Industrial robots are usually position-controlled, which enables precise movement of the TCP along a desired trajectory. In order to achieve a good result with robot-assisted grinding, in many applications it is necessary to regulate the process force (grinding force), which is often difficult to achieve with sufficient accuracy with conventional industrial robots. Own the large and heavy arm segments of an industrial robot Too great a mass inertia for a closed-loop controller to be able to react quickly enough to fluctuations in the process force. To solve this problem, a linear actuator, which is smaller than that of an industrial robot and which couples the TCP of the manipulator to the grinding tool, can be arranged between the TCP of the manipulator and the grinding tool. The linear actuator only regulates the process force (i.e. the contact force between the tool and the workpiece) while the manipulator moves the grinding tool together with the linear actuator in a position-controlled manner along a predeterminable trajectory.

Grinding machines such as orbital grinding machines work with thin, flexible and removable grinding disks which are attached to a carrier disk. The grinding wheel consists, for example, of paper (or another fiber composite material) coated with abrasive grains and can be attached to the carrier disk, for example, by means of a hook and loop fastener (hook and loop fastener, Velcro fastener). Even with robot-assisted grinding devices, worn grinding wheels are often changed manually. Although there are some concepts for robot-supported changing stations for changing grinding wheels, known solutions are comparatively complex, complex to implement and therefore expensive. For example, the publication describes EP 2 463 056 A2 a robot-assisted grinding machine with a device for the automated stripping of used grinding machines and a method for the automatic assembly of new grinding wheels. The publication WO 2015/125068 A1 discloses a circular cylindrical container for attaching a grinding wheel to a grinding machine. The container contains a stack of grinding wheels and has an upper opening and an actuator which pushes the grinding wheels towards the upper opening. However, the inventor has recognized some shortcomings of these and other known devices and methods in some applications (for example in orbital grinders).

An object on which the present invention is based can therefore be seen in providing improved devices and corresponding methods for removing grinding wheels from a grinding machine and mounting grinding wheels on a grinding machine.

SUMMARY

The above-mentioned object is achieved by the device for automatically fastening a grinding wheel according to claim 1, by the method according to claim 11 and by the system for changing grinding wheels of a robot-assisted grinding device according to claim 16. Different embodiments and further developments are the subject of the dependent claims.

A device is described for automatically loading a grinding machine, a robot-assisted grinding device, with a grinding wheel. According to one embodiment, the device has a support for receiving a stack of grinding wheels and a frame. The frame is arranged essentially parallel to the support so that the stack of grinding wheels is located between the support and the frame, the frame ends only partially overlapping the outer edge of the uppermost grinding wheel of the stack. The device further comprises a mechanical pretensioning unit which is coupled to the frame in such a way that a defined force is exerted by the frame on the stack of grinding wheels

In addition, a method for automatically mounting a grinding wheel on a robot-assisted grinding device is described. According to one exemplary embodiment, the method comprises aligning a carrier disk of a grinding machine by means of a manipulator, so that an underside of the carrier disk is essentially parallel to an upper side of a stack of grinding wheels. The method further comprises pressing the carrier disk against the stack of grinding wheels by means of an actuator which is coupled between the manipulator and the grinding machine, so that the uppermost grinding wheel of the stack of grinding wheels adheres to the carrier disk. Finally, the grinding machine together with the grinding wheel is raised by means of the manipulator and / or the actuator.

Finally, a system for changing grinding wheels of a robot-assisted grinding device is described. According to one embodiment, the system has a magazine for receiving a stack of grinding wheels, a manipulator which is designed to position and move the grinding machine relative to the magazine, and an actuator (20) which is arranged between the grinding machine and manipulator and is designed for this purpose, the grinding machine against the top grinding wheel of the Press stack of grinding wheels. The relative movement between the grinding machine and the magazine is brought about exclusively by the manipulator or by the manipulator and the actuator (20).

BRIEF DESCRIPTION OF THE DRAWINGS

• Figur 1 zeigt schematisch ein Beispiel einer robotergestützten Schleifvorrichtung.
• Figur 2 zeigt schematisch das Schleifwerkzeug und die Schleifscheibe sowie die Befestigung der Schleifscheibe auf dem Schleifwerkzeug.
• Figur 3 zeigt eine isometrische Darstellung einer Schleifmaschine mit einem Linearaktor zur Regelung der Prozesskraft.
• Figuren 4A-C zeigen ein erstes Beispiel einer Vorrichtung zum automatischen Abziehen einer Schleifscheibe von dem Schleifwerkzeug aus Fig. 3 sowie die Verwendung der Vorrichtung, welche keinen eigenen Antrieb benötigt.
• Figuren 5A-C zeigen das gleiche Beispiel aus Fig. 4, wobei der Abziehvorgang der Schleifscheibe genauer dargestellt ist.
• Figuren 6A-D zeigen ein zweites Beispiel einer Vorrichtung zum automatischen Abziehen einer Schleifscheibe von dem Schleifwerkzeug aus Fig. 3 sowie die Verwendung der Vorrichtung, welche ebenfalls keinen eigenen Antrieb benötigt.
• Figuren 7A-D zeigen ein drittes Beispiel einer Vorrichtung zum automatischen Abziehen einer Schleifscheibe von dem Schleifwerkzeug aus Fig. 3 sowie die Verwendung der Vorrichtung, wobei diese einen separaten Antrieb aufweist.
• Figur 8A-B zeigen die Ausrichtung der Winkelstellung der Schleifscheibe im Falle einer Orbitalschleifmaschine.
• Figur 9 zeigt ein Beispiel einer kamerabasierten Ausrichtung der Winkelstellung der Schleifscheibe.
• Figur 10 zeigt ein Beispiel der Ausrichtung der Winkelstellung der Schleifscheibe mittels Abstandssensoren.
• Figur 11 zeigt ein Beispiel einer Vorrichtung zum automatischen Befestigen einer (unverschlissenen) Schleifscheibe an dem Schleifwerkzeug aus Fig. 3 sowie die Verwendung der Vorrichtung, welche ebenfalls keinen eigenen Antrieb benötigt.
• Figur 12 zeigt eine Draufsicht auf ein Schleifpapiermagazin, wie es in der Vorrichtung gemäß Fig. 8 verwendet wird.
• Figur 13 ist ein Flow-Chart zur Darstellung eines Beispiels des hier beschriebenen Verfahrens zum automatischen Wechseln von Schleifscheiben.

The invention is explained in more detail below with reference to the examples shown in the figures. The illustrations are not necessarily true to scale and the invention is not limited to the aspects shown. Rather, it will It is important to illustrate the principles on which the invention is based. In the pictures shows:

• Figure 1 shows schematically an example of a robotic grinding device.
• Figure 2 shows schematically the grinding tool and the grinding wheel as well as the fastening of the grinding wheel on the grinding tool.
• Figure 3 shows an isometric view of a grinding machine with a linear actuator for controlling the process force.
• Figures 4A-C show a first example of a device for automatically removing a grinding wheel from the grinding tool Fig. 3 and the use of the device, which does not require its own drive.
• Figures 5A-C show the same example Fig. 4 , the process of honing the grinding wheel is shown in more detail.
• Figures 6A-D show a second example of a device for automatically removing a grinding wheel from the grinding tool Fig. 3 and the use of the device, which also does not require its own drive.
• Figures 7A-D show a third example of a device for automatically removing a grinding wheel from the grinding tool Fig. 3 and the use of the device, which has a separate drive.
• Figure 8A-B show the orientation of the angular position of the grinding wheel in the case of an orbital grinder.
• Figure 9 shows an example of a camera-based alignment of the angular position of the grinding wheel.
• Figure 10 shows an example of the alignment of the angular position of the grinding wheel by means of distance sensors.
• Figure 11 shows an example of a device for automatically attaching a (unworn) grinding wheel to the grinding tool from Fig. 3 and the use of the device, which also does not require its own drive.
• Figure 12 shows a plan view of a sandpaper magazine as it is in the device according to FIG Fig. 8 is used.
• Figure 13 Figure 3 is a flow chart showing an example of the method described herein for automatically changing grinding wheels.

DETAILED DESCRIPTION

Before various exemplary embodiments of the present invention are explained in detail, an example of a robot-assisted grinding device will first be described. This includes a manipulator 1, for example an industrial robot and a grinding machine 10 with a rotating grinding tool (eg an orbital grinding machine), this being coupled to the so-called tool center point (TCP) of the manipulator 1 via a linear actuator 20. In the case of an industrial robot with six degrees of freedom, the manipulator can be constructed from four segments 2a, 2b, 2c and 2d, which are each connected via joints 3a, 3b and 3c. The first segment is usually rigidly connected to a foundation 41 (but this does not necessarily have to be the case). The joint 3c connects the segments 2d and 2d. The joint 3c can be 2-axis and enable a rotation of the segment 2c about a horizontal axis of rotation (elevation angle) and a vertical axis of rotation (azimuth angle). The joint 3b connects the segments 2b and 2c and enables a pivoting movement of the segment 2b relative to the position of the segment 2c. The joint 3a connects the segments 2a and 2b. The joint 3a can be 2-axis and therefore (similar to the joint 3c) enable a pivoting movement in two directions. The TCP has a fixed position relative to the segment 2a, this usually also comprising a swivel joint (not shown) that enables a rotary movement about a longitudinal axis of the segment 2a (in Fig. 1 shown as a dash-dotted line, corresponds to the axis of rotation of the grinding tool). Each axis of a joint is assigned an actuator that can cause a rotary movement about the respective joint axis. The actuators in the joints are controlled by a robot controller 4 in accordance with a robot program.

The manipulator 1 is usually position-controlled, ie the robot controller can determine the pose (location and orientation) of the TCP and move it along a predefined trajectory. In Fig. 1 is the longitudinal axis of segment 2a, on which the TCP lies, denoted by A. When the actuator 20 rests against an end stop, the pose of the TCP also defines the pose of the grinding tool. As already mentioned at the beginning, the actuator 20 serves to set the contact force (process force) between the tool (grinding machine 10) and workpiece 40 to a desired value during the grinding process. A direct force control by the manipulator 1 is usually too imprecise for grinding applications, since due to the high inertia of the segments 2a-c of the manipulator 1, rapid compensation of force peaks (e.g. when the grinding tool is placed on the workpiece 40) with conventional manipulators is practically impossible is possible. For this reason, the robot controller is designed to regulate the pose of the TCP of the manipulator, while the force regulation is carried out exclusively by the actuator 20.

As already mentioned, during the grinding process, the contact force F _K between the tool (grinding machine 10) and the workpiece 40 can be set with the aid of the (linear) actuator 20 and a force control (which can be implemented in the controller 4, for example) so that the contact force (in the direction of the longitudinal axis A) between the grinding tool and workpiece 40 corresponds to a predeterminable setpoint value. The contact force is a reaction to the actuator force with which the linear actuator 20 presses on the workpiece surface. If there is no contact between the workpiece 40 and the tool, the actuator 20 moves against an end stop due to the lack of contact force on the workpiece 40. The position control of the manipulator 1 (which can also be implemented in the controller 4) can work completely independently of the force control of the actuator 20. The actuator 20 is not responsible for the positioning of the grinding machine 10, but only for setting and maintaining the desired contact force during the grinding process and for detecting contact between the tool and the workpiece. The actuator can be a pneumatic actuator, for example a double-acting pneumatic cylinder. However, other pneumatic actuators can also be used, such as bellows cylinders and air muscles. As an alternative, electrical direct drives (gearless) can also be considered. It should be noted that the effective direction of the actuator 20 does not necessarily have to coincide with the longitudinal axis A of the segment 2a of the manipulator.

In the case of a pneumatic actuator, the force control can be implemented in a manner known per se with the aid of a control valve, a regulator (implemented in the controller 4) and a compressed air reservoir. However, the specific implementation is not important for the further explanation and is therefore not described in more detail.

The grinding machine 10 has a grinding disk 11 which is mounted on a carrier disk 12 ( backing pad ). The surface of the carrier disk 12 or the rear surface of the grinding wheel 11 or both surfaces are designed in such a way that the grinding wheel 11 readily adheres to the carrier disk 12 upon contact. For example, a Velcro fastener ( hook and loop fastener ) is used so that the grinding disk 11 remains adhered to the carrier disk. A releasable locking connection or the like would also be conceivable. Fig. 2a shows the grinding machine 10 with the grinding wheel 11 mounted. In the present example, the grinding machine 10 is an orbital grinding machine in which the carrier disk 12 together with the grinding wheel 11 is driven via an eccentric bearing so that the axis of rotation A has an eccentricity e that corresponds to the distance between the axes A and A 'corresponds to. In operation, the carrier disk is driven by an electric motor of the grinding machine 10 and the grinding wheel 11 rotates with the carrier disk 12. In the case of an orbital grinding machine, the carrier disk 12 performs a more complex movement, namely a rotation around two parallel axes of rotation with a defined offset. The grinding wheel 11 consists, for example, of paper (or another fiber composite material) coated with abrasive grains, is flexible (bendable) and can be pulled off the carrier disk. Figure 2b shows the grinding machine 10 with the grinding wheel 11 removed. The grinding wheel 11 (and also the carrier disk 12) can have holes H through which grinding dust can be sucked off. An example of a perforated grinding wheel is in Figure 2c shown. Both the holes H and the eccentricity e of the grinding wheel can cause problems when installing new grinding wheels, since both the angular position of the carrier disk 12 (and thus also the position of the holes H) in relation to the axis of rotation A 'and the angular position of the Axis of rotation A 'with respect to the longitudinal axis A (axis of symmetry) are a priori undefined. Furthermore, it can also happen that the assembly of a new grinding wheel fails without the robot controller noticing the error, with the result that the robot tries to grind the workpiece without the grinding wheel 11 and thereby destroys the carrier disk 12.

In Fig. 3 a further example of a grinding machine 10 mounted on an actuator 20 is shown. The actuator 20 has a first flange 21 which is rigidly connected to the manipulator 1 (for example segment 2a in FIG Fig. 1 ) can be connected. The TCP of the manipulator can be in the middle of the flange 21, for example. at the end of the actuator 20 opposite the flange 21 is a second flange (in Fig. 3 covered) on which the grinding machine 10 is mounted. In Fig. 3 For example, the connection 15 for a hose through which the grinding dust is extracted is also shown. In the other pictures. Despite the automation of the grinding process with robot-assisted grinding devices, the grinding wheel is often still changed manually, in that an operator grips the grinding wheel 11 at the edge with his thumb and forefinger and then pulls it off the carrier disk. Existing automatic solutions for automatically changing grinding wheels are relatively complicated, the complexity arising, for example, from the fact that the grinding wheel 11 has to be gripped by a mechanical device before it is removed. In the Fig. 4 , 5 and 6th various exemplary embodiments of devices are shown with the aid of which grinding wheels can be automatically pulled off a grinding machine. In Fig. 7 a device is shown with the help of which grinding wheels can be automatically connected to the carrier disk of a grinding machine of a robot-assisted grinding device.

The figures in Figures 4A to 4D show the device Fig. 3 (Grinding machine 10 including actuator 20) and an example of a detachment device 2 for detaching the grinding wheel 11 from the grinding machine 10 in different situations during the removal of the grinding wheel 11 Fig. 4 In the example shown, the device for removing a grinding wheel from a grinding machine with a rotating grinding wheel comprises a frame 31, a separating plate 32 connected to the frame 31 and a support surface connected to the frame 31. Partition plate 32 and the support surface are coupled to frame 31 in such a way that a relative movement between partition plate 32 and support surface 33 along a first direction (see FIG Figure 4A , Direction x) is made possible. In the present example the support surface is a roller conveyor 33. Pins 39 can be attached to the frame, the purpose of which will be given later with reference to FIG Fig. 8 is explained.

The roller conveyor 33 consists of several parallel axes 35, on each of which one or more rollers 34 are mounted in such a way that they revolve around the respective Can rotate axes (see Figures 4B and 4C ). The length of the axes 35 corresponds approximately to the width of the roller conveyor 33. The two ends of each axis are mechanically connected to the frame, in the present example the axes 35 are clamped to the frame 31 via a clamping component (clamping piece 36) (e.g. by means of screws). The individual rollers 34 can be mounted on the axles via a roller bearing or a plain bearing. The frame 31 and thus also the roller conveyor 33 are so wide that one with a manipulator 1 (see Fig. 1 ) connected grinding machine 10 can be pressed against the support surface (defined by the roller conveyor 33) that the grinding wheel 11 mounted on the grinding machine rests against the support surface. The flat grinding wheel 11 lies approximately parallel to the axes 35. The pressing of the grinding machine against the contact surface defined by the roller conveyor 33 is carried out, for example, by the actuator 20, which also enables the contact force between the roller conveyor 30 and the grinding wheel 11 to be regulated. Unlike during the grinding process, however, precise control of the contact force is not absolutely necessary.

The rollers 34 of the roller conveyor 33 enable the grinding machine 10 and thus the grinding wheel 11 to be displaced along the direction x (towards the separating plate 32). The displacement movement of the grinding wheel along the roller conveyor 33 is specified by the manipulator 1. the rollers 34 or the partition plate 32 do not require a separate drive. While the grinding wheel 11 is moved in the x-direction towards the separating plate 32, the rollers 34 rotate due to the rolling friction between rollers 34 and grinding wheel 11. The rolling movement of the rollers 34 largely prevents material abrasion from the roller conveyor 33.

Figure 4B shows the beginning of the grinding wheel removal process. As mentioned, the manipulator 1 moves the grinding machine along the roller conveyor 33 towards the separating plate 32. The separating plate 32 is arranged relative to the roller conveyor 33 in such a way that - when the grinding machine 10 with the grinding wheel 11 is pressed against the roller conveyor 33 - an edge of the separating plate 32 penetrates between the grinding wheel 11 and the carrier disk 12 and the adhesion between the two parts (grinding wheel 11 and carrier disk 12) releases. In the case of a Velcro fastener between the grinding wheel 11 and the carrier disk 12, this is successively released by the separating plate 32, while the separating plate 32 is pushed between the grinding wheel 11 and the carrier disk 12. In the detail view A of the Figure 4B a situation is shown in which the partition plate 32 is immediately before the Penetration into the space between the grinding wheel 11 and the carrier disk 12 is located while the grinding machine 10 is moved over the roller conveyor 33 towards the separating plate 32. In Figure 4C a situation is shown in which the separating plate 32 along the direction of movement of the grinding machine 10 (direction x) almost completely penetrates the space between the grinding wheel 11 and the carrier disk 12. An adhesive connection between the grinding wheel 11 and the carrier wheel 12 now only exists locally in the edge regions of the grinding wheel.

When the separating plate 32 has penetrated so far into the space between the grinding wheel 11 and the carrier disk 12 that a large part of the adhesive connection between the grinding wheel 11 and the carrier disk 12 has been loosened, the grinding machine 10 can be lifted off the separating plate 32 (along the direction y, see FIG Figure 4D ), whereby the grinding wheel 11 is completely withdrawn from the carrier disk 12 and falls off the carrier disk 12 (due to gravity). The process of removing the grinding wheel is thus ended and the grinding machine 10 is ready to accept a new grinding wheel 11. The lifting movement of the grinding machine 10 in the y direction can be brought about either by the actuator 20 or by the manipulator 1 (or both).

Figure 4E shows, in a simplified sectional view, a situation similar to that in FIG Figure 4B , in which the separating plate 32 has just penetrated a short distance into the area between the carrier disk 12 and the grinding disk 11. Furthermore, a color sensor 62 is shown, which is arranged such that it is directed towards the underside of the partition plate 32. That is, the sensor 62 "sees" either the underside of the separating plate 32 or the grinding wheel 11 pushed through between the sensor 62 and the separating plate 32. The color sensor 62 can be designed to detect a specific adjustable color (color detector). For example, the color sensor 62 can be calibrated to the color of the partition plate 32 (target color is the color of the partition plate 32). A binary sensor signal, for example, indicates whether there is an object with the target color in front of the sensor (ie in the detection area / field of view of the sensor).

If the separating plate 32 penetrates as desired between the carrier disk 12 and the grinding wheel 11 during the detachment process, the color sensor 62 first "sees" the (e.g. metallic) color of the separating plate 32 and then (if the separating plate 32 has penetrated far enough) the color of the grinding wheel (and no longer the color of the partition plate 32). The color sensor 62 signals the controller (for example robot controller or upstream Control unit) that the separating plate 32 is no longer visible, which indicates that the detachment process has been properly initiated. If the color of the separating plate 32 remains visible, this indicates that the separating plate 32 has not threaded properly between the carrier disk 12 and the grinding wheel 11, as is shown in detail X. The robot controller can recognize this (undesired) situation with the aid of the color sensor 62 and, for example, start a second attempt to detach the grinding wheel 11 from the carrier wheel 12. Alternatively (or if the second attempt also fails), the robot controller can automatically move the manipulator together with the grinding machine to a maintenance position. Instead of the color sensor 62, sensors based on color detection can also be used. For example, a proximity sensor / proximity switch can also be used instead of a color sensor. For example, optical proximity sensors, ultrasonic proximity sensors and inductive or capacitive proximity sensors or proximity switches come into consideration.

Figures 5A-C show the same example Fig. 4 , the process of detaching the grinding wheel 11 from the carrier disk 12 of the grinding machine 10 is shown in more detail. The left figures in Figures 5A-C are isometric representations and the images on the right show the appropriate top view. For clarity are in Fig. 5 only the device for removing the grinding wheel 10 and the grinding wheel 11 are shown. The grinding machine 10 and the actuator 20 have been omitted for the sake of clarity. The Figures 5A, 5B and 5C show the process of detachment of the grinding wheel 11 in three chronologically successive points in time. The edge sequence of the separating plate 32 facing the grinding wheel comprises the three edges K0, K1 and K2 (see Figure 5A ), the edge K0 being essentially parallel to the axes 35 of the roller conveyor 33 (that is, normal to the feed direction x of the grinding wheel). The length d _{0 of} the edge K ₀ (see Figure 5A , left drawing) is significantly smaller than the diameter d _{1 of} the grinding wheel 11 (for example 2 · d ₀ <d ₁ ). Along the x-direction, the width b (x) of the partition plate 32 increases continuously (where b (0) = d ₀ ) up to a maximum width which depends on the width of the frame 31. The width b (x) defines the distance between the lateral edges K1 and K2 of the partition plate 32, which are shown in FIG Figure 5A (right drawing) are marked with dashed lines. The edges K0, K1 and K2 can be straight (in this case the right part of the partition plate would be trapezoidal). In the example shown, only the front edge K0 is straight (slightly rounded at the corners) and the edges K1 and K2 are curved.

The situation in Figure 5A essentially corresponds to the situation in Figure 4B . That is, the separating plate 32 (specifically the foremost edge K0 of the separating plate) is located immediately in front of the penetration into the space between the grinding wheel 11 and the carrier disk 12, while the grinding machine 10 is moved towards the separating plate 32 via the roller conveyor 33. The grinding wheel 11 is initially detached only in a very narrow area (width b (0) = d ₀ ), which becomes wider (width b (x)) as the separating plate 32 penetrates into the space between the grinding wheel 11 and the carrier disk 12. The edges K1 and K2 can be shaped in such a way that with a constant feed speed of the grinding wheel 11 in the x-direction, the grinding wheel is loosened on a constant surface per unit of time, which can keep the load on the Velcro fastener constantly low. The partition plate 32 (and its edges K0, K1, K2) is shaped in this way. that - when the edge K0 has completely passed through the space between the grinding wheel 11 and the backing wheel 12 - the grinding wheel 11 still adheres to comparatively small areas A1 and A2 on the edge of the grinding wheel 11 on the backing wheel 12. This situation is in Figure 5B shown. In Figure 5C has the grinding wheel 11 compared to Figure 5B moved even further in the x-direction and the surfaces A1, A2 to which the grinding wheel 11 still adheres are already relatively small. In this situation, the grinding wheel has already completely left the roller conveyor 33. If the grinding wheel 11 - starting from the in Figure 5C situation shown - is moved further in the x-direction, the sum of the areas A1 + A2 approaches zero and the grinding wheel is completely detached and can fall out of the device at the bottom. The way down is no longer blocked by the roller conveyor 33, since the grinding wheel 11 is only finally detached from the carrier disk 12 after the grinding wheel 11 has left the roller conveyor 12. In this way, jamming or “sticking” of the grinding wheel 11 between the roller conveyor and the separating plate 32 is prevented. Alternatively, starting from the in Figure 5C the situation shown, the grinding machine can also be lifted. In this case, the grinding wheel 11 is also completely detached from the carrier wheel 12 (see also FIG Figure 4D ).

In the example Fig. 4 and 5 the support surface for the grinding wheel 11 to be removed is formed by the roller conveyor 33. Instead of a roller conveyor 33, a slide that can be displaced along a linear guide can alternatively be used. An example of this variant is in Fig. 6 shown. The figures in Figures 6A to 6E show the device Fig. 3 (Grinding machine 10 including actuator 20) and a device for Pulling off the grinding wheel 11 from the grinding machine 10 in different situations during the removal of the grinding wheel 11. According to the in Fig. 6 The example shown comprises the device for removing a grinding wheel from a grinding machine with a rotating grinding wheel - similar to the previous example Fig. 4 a frame 31, a partition plate 32 connected to the frame 31 and a support surface connected to the frame 31, which in the present case is formed by a slide 33b which is mounted displaceably along a linear guide. The linear guide is formed, for example, by a disk 33a mounted on the frame 31, on which the slide 33b runs along one direction (see FIG Figures 6A and 6B , x-direction) can slide.

The frame 31 and the carriage 33b are so wide that one with a manipulator 1 (see Fig. 1 ) connected grinding machine 10 can be pressed against the support surface (defined by the carriage 33b) that the grinding wheel 11 mounted on the grinding machine rests on the support surface. The flat grinding wheel 11 lies approximately parallel to the direction of movement (x-direction) of the slide 33b. The grinding machine is pressed against the slide 33b, for example, by the actuator 20, which also enables the contact force between the roller conveyor 30 and the grinding wheel 11 to be regulated. As already mentioned, an exact regulation of the contact force is not absolutely necessary (in contrast to grinding). The contact pressure between grinding wheel 11 and carriage 33b should, however, be so great that the resulting static friction prevents a relative movement between grinding wheel 11 and carriage 33b.

The slide 33b mounted on the rail 33a enables the grinding machine 10 and thus the grinding wheel 11 to be displaced along the direction x (towards the separating plate 32) without a relative movement being carried out between the slide 33b and the grinding wheel 11. This largely prevents material abrasion from the slide. The displacement movement of the grinding wheel 11 (and of the carriage 33b) along the rail 33a is predetermined by the manipulator 1. The carriage 33b or the partition plate 32 do not require a separate drive.

Figure 6B shows the beginning of the grinding wheel removal process. As mentioned, the manipulator 1 moves the grinding machine, pressed against the slide 33b, towards the separating plate 32. The separating plate 32 is arranged relative to the slide 33b in such a way that - when the grinding machine 10 with the grinding wheel 11 is pressed against the support surface (on the slide 33b) - an edge of the separating plate 32 between the grinding wheel 11 and support disk 12 penetrates, the adhesion between the two parts (grinding disk 11 and support disk 12) is released and the grinding disk 11 is trapped between separating plate 32 and slide 33b. This situation is in Figure 6C shown. In the case of a Velcro fastener between the grinding wheel 11 and the carrier disk 12, this is successively released by the separating plate 32, while the separating plate 32 is pushed between the grinding wheel 11 and the carrier disk 12 (see FIG Figure 6C ).

As soon as the grinding wheel 11 is clamped between the separating plate 32 and the slide 33b, the grinding machine 10 (including the carrier disk 12) can be lifted from the slide (in the y-direction, normal to the support surface), whereby the clamped grinding wheel is completely pulled off the carrier disk 12 . This situation is in Figure 6D shown. The process of removing the grinding wheel is thus ended and the grinding machine 10 is ready to accept a new grinding wheel 11. The movement of the lifting off of the grinding machine 10 in the y-direction can (as in the example from Fig. 4 ) be effected either by the actuator 20 or by the manipulator 1 (or both).

In order to release the clamping of the grinding wheel 11 between the separating plate 32 and the slide 33b again, the slide 33b must be pushed back into the starting position (away from the separating plate 32). This can either be done automatically if, for example, the carriage 33b is coupled to the frame 31 via a spring, which is tensioned when the carriage is moved in the x direction and pushes the carriage 33b back into the starting position after the grinding machine 10 has been lifted off the support surface. Alternatively, the manipulator 1 can also be programmed in such a way that it presses against the slide 33b with the grinding machine 10 or an arm segment in such a way that it generates a force F (see FIG Figure 6E ) exerts on the carriage 33b against the x-direction. A short push can be enough to bring the slide 33b to its starting position (in Figure 6A shown) and to release the grinding wheel 11 from the clamp. The grinding wheel then falls off the device due to gravity. This situation is in Figure 6E shown.

As already mentioned, the devices for removing grinding wheels according to the Fig. 4 , 5 and 6th no drive of its own. The necessary relative movement between the grinding machine 10 and the separating plate 32 is essentially predetermined by the manipulator 1, which carries the grinding machine 10. The contact force between The support surface and the grinding machine 10 are primarily effected by the actuator 20. In the Fig. 7 The variant shown functions essentially in the same way as the exemplary embodiment Fig. 6 In this case, the grinding machine 10 with the grinding wheel 11 is pressed onto a stationary support surface while the separating plate 32 moves towards the grinding wheel 11. For this purpose, the partition plate 32 is mounted displaceably relative to a support frame 31 by means of a linear guide, the displacement movement being effected by a separate linear drive 34 which is mechanically coupled between the (displaceably mounted) partition plate 32 and the support frame 31. The partition plate 32 is mounted on the support frame 31, for example, via rails 31a which are arranged on the left and right of the partition plate 32.

Figure 7A shows the device after the grinding machine 10 with its grinding wheel has been placed on the support surface 33 '. The partition plate 32 is in an initial position remote from the grinding machine. The drive 34 of the separating plate 32 is activated and the separating plate 32 moves towards the grinding wheel 11. Figure 7B shows a situation in which the separating plate 32 is just about to penetrate into the space between the grinding wheel 11 and the carrier wheel 12 of the grinding machine and to clamp the grinding wheel 11 between the separating plate 12 and the support surface 33 ', while the connection between the grinding wheel 11 and the carrier wheel 12 is released. Figure 7C shows a situation in which the separating plate 32 clamps the grinding wheel 11 against the support surface 33 '. In this situation, the grinding machine 10 (including the carrier disk 12) can be lifted off the support surface 33 '(in the y-direction, normal to the support surface), whereby the clamped grinding wheel 11 is completely pulled off the carrier disk 12. This situation is in Figure 7D shown. The process of removing the grinding wheel is thus ended and the grinding machine 10 is ready to accept a new grinding wheel 11. The movement of the lifting off of the grinding machine 10 in the y-direction can (as in the example from Fig. 4 ) be effected either by the actuator 20 or by the manipulator 1 (or both). The separating plate 32 can be moved back into its starting position with the aid of the linear drive.

In the case of an orbital grinding machine, the grinding wheel 11 does not rotate about a central axis of rotation, but executes a more complex movement that can be described by two axes of rotation D1, D2 (see FIG Figure 8A ). In the examples described here, the axis of rotation D2 corresponds to the longitudinal axis A (see Figs. 1 and 2 ), on which the TCP also lies (which does not necessarily have to be the case), and the axis of rotation D1 of the in Fig. 2a illustrated eccentric axis of rotation A '. The grinding wheel 11 rotates about an axis of rotation D1, which moves along a path about a second axis of rotation D2. The distance between the axes of rotation D1 and D2 is called the eccentricity. When the rotational movement of the grinding wheel 11 stops, the angular position of the axis of rotation D1 on its path about the axis of rotation D2 is practically random. In particular if the grinding wheel 11 and the carrier wheel 12 - as in FIG Figure 2c shown - is perforated (to enable extraction of the grinding dust, but the holes are in Fig. 8 not shown) it can be important that the axes of rotation D1 and D2 of the carrier disk 12 are in a defined position relative to one another before a new grinding wheel is applied and that the angular position of the grinding wheel is clearly defined in relation to the axis of rotation D1. In the case of round carrier disks 12, as in FIG Fig. 8 shown, the support disk of a grinding machine are pressed by the manipulator 1 (in the z-direction) against a stop with two spaced apart, for example cylindrical, pins 39, which can be attached to the support frame 31, for example (see also Figure 4A ). As a result of this pressing, the axes of rotation D1 and D2 are aligned along an axis of symmetry S between the pins 39 and brought into a defined reference position. This situation is in Figure 8B shown. If the grinding machine 10 has a motor in which the angular position of the motor shaft is adjustable (for example a synchronous motor with rotary encoder ), the desired reference position can also be set by a corresponding control of the (electric) motor of the grinding machine. Instead of the pens, non-cylindrical objects can also be used. The stop essentially has two pins (or abstractly edges which run parallel to the axis of rotation D1), and the carrier disk 12 is pressed against the edges on the circumferential side.

Additionally or alternatively to the mechanical alignment of the axes of rotation according to FIG Fig. 8 a camera-based alignment can also be provided, which is shown in Fig. 9 is sketched. Even if the axes of rotation D1 and D2 are as shown in Figure 8B shown are aligned along a defined straight line, the angular position of the carrier disk 12 with respect to the axis of rotation D1 is not necessarily known. This can then be determined, for example, by means of a camera. A camera-based alignment of the grinding machine 10 (and thus of the carrier disk 12) can also be considered in the case of more complex grinding wheel geometries (for example triangular). For this purpose, the grinding machine 10 is aligned in such a way that the carrier disk 12 (that is, the plane in which the grinding disk is arranged) is perpendicular to the optical axis O of the camera 6. Since the position of the optical axis is known a priori is, then the manipulator 1 can easily position the grinding machine. If the carrier disk 12 has a hole pattern, this can be detected by means of simple image processing algorithms. The image processing algorithm can detect the angular position of the carrier disk, for example, based on a geometry of the hole pattern recognizable on a camera image, or based on the color (and / or the brightness) of the holes (one hole H will have a different color on the camera image than the rest Carrier disk 12). A correction angle ϕ can then easily be calculated from the detected hole pattern, by which the manipulator 1 must rotate the grinding machine 10 (axis of rotation is the optical axis O) in order to achieve a desired, defined angular position of the carrier disk. The image processing unit 9 can be in the robot controller 8 (see Fig. 1 ) integrated or designed as a separate hardware unit. For example, the calculated correction angle ϕ is transferred from the image processing unit 9 to the robot controller 8. After the support disk 12 of the grinding machine has a defined angular position, a new grinding disk can be attached to the support disk. A suitable device for this is in Figures 11 and 12 shown.

Fig. 10 shows the arrangement of the grinding machine 10 (including the carrier disk 12) on a proximity sensor 61 (proximity sensor). Is shown - as in Fig. 9 - For simplicity, only the carrier disk 12, which, however, is mounted on the grinding machine 10. With the help of the manipulator (cf. Fig. 1 ) the grinding machine 10 together with the carrier disk 12 can be positioned relative to a proximity sensor 61 in such a way that the proximity switch is aimed precisely at a point on the carrier disk 12 at which a hole H should be located. If there is actually a hole H at the desired position, this desired state (desired angular position of the carrier disk 12) is detected by the proximity sensor. If there is no hole at the desired location, the carrier disk 12 can be rotated until the proximity sensor 61 detects a hole H. The carrier disk 12 can be rotated, for example, in that the manipulator rotates the entire grinding machine 10 including the carrier disk 12 about the axis A (for example by an angle ϕ as in FIG Fig. 10 shown).

The proximity sensor 61 can be, for example, an optical sensor which is suitable for determining the distance from the carrier disk 12. If the “proximity sensor 61” “sees” a hole H, the measured distance is greater than in a situation in which there is no hole in the detection range of the sensor. The proximity sensor 61 can also have a digital output that outputs a logic signal. This logic signal indicates whether a hole is detected or not. Such a proximity sensor is also referred to as a proximity switch . In one example, the proximity switch 61 is not sensitive to the distance to the carrier disk 12, but to the color. That is, the sensor 61 is sensitive to a (specific and adjustable color). As soon as a hole H is in the detection area (field of view) of the sensor 61, the sensor “sees” a different color and can signal the detection of the hole H (for example via a logic signal). The proximity sensor 61 can also use other than optical detection principles. For example, ultrasonic proximity sensors can also be used. If the carrier plate contains iron or other metals, inductive or capacitive proximity sensors can also be used.

In Fig. 11 two devices 5 and 5 'are shown next to one another for automatically equipping a grinding machine 10 with a grinding wheel 11, the grinding machine 10 (including actuator 20, see FIG Fig. 1 and 3rd ) is moved with the aid of a manipulator 1. The devices 5 and 5 'are practically identical, the device 5 (left) having a full magazine with grinding wheels 11 and the device 5' (right) an almost empty magazine with grinding wheels 11. The device 5 or 5 'comprises a support 53, on which a stack of grinding wheels 11 can be arranged. The support 53 is attached, for example, to a carrier 60 and can be rigidly connected to it. To stabilize the stack laterally, several guide rods 51 are arranged around the stack (in the circumferential direction of the grinding wheels 11). The guide rods 51 run essentially normal to the surface of the support 53 (on which the grinding wheels lie) and are connected to the top of the stack via a ring 50 (for example by means of screws 53).

The guide rods 51 are, for example, cylindrical and mounted on the support 53 so as to be displaceable along their longitudinal axis. Regardless of the height of the stack of grinding wheels, the ring 53 rests (at least partially) on the topmost grinding wheel of the stack and the guide rods 51 stand - depending on the height of the stack of grinding wheels - below the support 53 from the latter. At the lower end of the guide rods 51, these are connected via a disk 56 in order to stabilize the position of the guide rods 51 relative to one another. A weight 55 can also be attached to the disk 56 in order to move the guide rods 51 with a defined force F _B (ie the weight of the weight 55). to pretension. The force F _B could, however, alternatively also be brought about by a spring or a linear actuator which acts between the disk 56 and the support 53. The force is transmitted to the upper ring 50 via the guide rods 51, so that the latter _{presses on the grinding wheel stack with essentially the same force F B} and holds the grinding wheels 11 in place. Depending on the specific design of the device 5 or 5 ', the weight 56 can also be omitted if the weight of the guide rods 51 and the disk 56 is large enough.

Fig. 12 shows a grinding wheel magazine 5 from above, so that the ring 50 and the grinding wheel stack can be seen in plan view. The grinding wheels 11 have an outer diameter of 2 · R ₂ and the ring 50 has a slightly larger inner diameter of 2 · R ₁ (R ₁ <R ₂ ). Furthermore, the ring 50 has one or more (in the present example four) projections 50a whose distance from the center of the grinding wheels is slightly smaller than R ₂ , which is why the projections protrude slightly beyond the outer edge of the grinding wheels 11 and the grinding wheels (with the force F _B ) press against the support 53 and hold the grinding wheels 11. In Fig. 12 the screws with which the guide rods 51 can be fixed to the ring 50 are also shown. The grinding wheels 11 are arranged in the stack with the back side up. As already mentioned, the back has an adhesive layer (for example part of a Velcro fastener).

In the right part of the Fig. 11 the almost empty grinding wheel magazine 5 'is shown in a situation in which a new grinding wheel 11 is being "picked up" by the robot-assisted grinding device (manipulator 1, actuator 20 and grinding machine 10). For this purpose, the manipulator positions the grinding machine 10 above the device 5 or 5 ′ in such a way that the (unequipped) carrier disk 12 of the grinding machine 10 is approximately parallel to the ring 50. The manipulator 1 can approach the device 5, 5 ′ from above until the grinding machine 10 makes contact with the ring 50 and thus also with the uppermost grinding wheel 11. A contact can be recognized, for example, by the fact that the actuator 20 moves from its end stop (maximum deflection of the actuator) to smaller deflections. For this purpose, the actuator 20 can have, for example, a displacement sensor which is designed to measure the deflection of the actuator 20. The measured values can, for example, be sent to the robot controller 4 (see Fig. 1 ) are supplied. As soon as there is contact between the carrier disk and the ring 50, the manipulator 1 can stop and the actuator 20 press with a defined force against the ring 50 and the back of the uppermost grinding wheel of the magazine, so that the grinding wheel 11 adheres to the carrier disk remains. The manipulator can then lift off the grinding machine 10 again. If the adhesion between the grinding wheel 11 and the backing wheel 12 of the grinding machine 10 is greater than the holding force F _B with which the ring 50 holds the grinding wheel in place, the grinding wheel 11 can be lifted off the stack with the grinding machine 10 and the subsequent grinding process can be carried out with a new grinding wheel 11 start. As soon as the grinding wheel is worn out, a new change process can be started and the grinding wheel, for example, with the device according to FIG Fig. 4 can be withdrawn again.

In the case of non-circular grinding wheel geometries, instead of the ring 50, it is also possible to use a frame with a different geometry which is adapted to the geometry of the grinding wheels. According to a general embodiment, a frame (for example the ring 50) is _{pressed from above with a defined force F B} onto a stack of grinding wheels 11 in order to hold it in place. The inner contour of the frame (see Fig. 12 , Radius R ₁ ) is slightly larger than the outer contour of the grinding wheels 11 (see Fig. 12 , Radius R ₂ ), with protrusions from the inner contour of the frame (see Fig. 12 , Projections 50a) protrude inwardly beyond the outer contour of the grinding wheels 11. The projections 50a and the grinding wheels thus overlap on a comparatively small area (compared to the total area of the grinding wheel 11) and the grinding wheel 11 adhering to the carrier wheel 12 can easily be lifted off the stack.

After the grinding machine 10 has been equipped with a new grinding wheel, a further color sensor 63 (or alternatively also the camera 6, cf. Fig. 9 ) can be used to automatically check (e.g. after equipping the grinding machine with a grinding wheel or before starting a grinding process) whether the grinding machine has been correctly equipped with a grinding wheel. This test procedure is in the right part of the Fig. 12 shown. The carrier disk 12 usually has a different color than unused grinding disks. Consequently, the color sensor 63 (or a camera operated as a color sensor) can be used to distinguish a carrier plate 12 equipped with a grinding wheel 11 from an unequipped carrier plate 12 on the basis of the color. For this purpose, the manipulator moves the grinding machine 10 from a receiving position on the magazine (cf. Figure 11A or 11B ) to a test position in the vicinity of the color sensor 63, so that it can "see" the front side of the grinding wheel 11 or (if the grinding wheel 11 is missing) the carrier disk. The color sensor 63 (color detector) can be set, for example, in such a way that it detects the color of the carrier plate 12. As soon as the carrier plate 12 based its color is recognized, an error signal ("Error: machine not equipped) can be sent to the robot controller 8. The robot controller can then start a new assembly process in order to equip the grinding machine 10 with a grinding wheel 11. This can prevent if an assembly process (see below, Figures 11 and 12 ) for whatever reason fails, the robot starts a grinding process without a grinding wheel, which would lead to the destruction of the carrier plate 12 (or the workpiece). Alternatively, the color sensor 63 can also be calibrated to the color of the (new) grinding wheels.

Fig. 13 uses a flow chart to illustrate an example of the above with reference to FIG Fig. 4-12 explained procedure for the automatic changing of grinding wheels. Not all of the steps shown are absolutely necessary in all implementations of the method. If a grinding process is over or a grinding wheel is worn out, the manipulator 1 (step S1) moves the grinding machine to the detachment device 2 and presses (with the help of the actuator 20) the grinding wheel against the support surface (e.g., see e.g. Figures 4A-D , Roller conveyor 33, Figures 6A-D , Carriage 33b, and Figures 7A-D , Support surface 33 '). After the grinding wheel has been placed on the support surface, the separating plate 32 and grinding machine 10 are moved towards one another (step S2) until the separating plate 32 threads between the carrier disk 12 of the grinding machine 10 and the grinding wheel 11 (see e.g. Figure 5A , 6B , 7B ). This movement can be brought about by the manipulator 1 (cf. Fig. 4 ) or from a separate drive of the detachment device (cf. Fig. 7 ). A color sensor can be used to check (step S3) whether the separating plate 32 has threaded correctly between the carrier disk 12 and the grinding disk 11 (see e.g. Figure 4E ). Other sensors (e.g. proximity sensors) can also be used instead. If the test turns out negative, the process can start from the beginning (for example at step S1) or it can be canceled. If the test is positive, the grinding wheel 11 is detached from the carrier plate as described above.

Orbital grinding machines and similar grinding machines have an eccentric axis of rotation. Furthermore, the grinding wheels can have holes H (see Fig. 2 , 9 and 10 ), which are used to extract grinding dust. These holes continue in the carrier disk 12, which is why the angular position of the carrier disk 12 (relative to the grinding wheel) should be well defined when a new grinding wheel is attached. First, the eccentric axis of rotation (see e.g. Fig. 8 , eccentric axis of rotation D1) is moved into a reference position (step S4). This can either - as in Fig. 8 shown - by pressing the carrier plate 12 against a stop (pins 39), or by appropriately controlling the motor of the grinding machine, provided that it has an angle encoder. When the eccentric axis of rotation is in a defined reference position, the grinding machine 10 (as a whole) can still be rotated by the manipulator 1 around the longitudinal axis (see e.g. Fig. 2 , Longitudinal axis A, Fig. 8 , Axis of rotation D2) are rotated until the holes H come to lie in the desired angular position (target position) (step S5). Reaching the target position can be detected, for example, with a proximity sensor (e.g. proximity switch or color sensor) or by means of a camera (see e.g. Figures 9 and 10 ). This step is of course optional for grinding wheels without holes.

With the eccentric axis of rotation in the reference position and possibly the holes in a target position, the grinding machine 10 is moved towards the magazine with the new grinding wheels and (step S6) the carrier plate 12, e.g. with the help of manipulator 1 and actuator 20, against the top of the magazine pressed (see Fig. 11 ). Due to the contact pressure between the carrier disk 12 and the grinding wheel 11, the Velcro fastener gets caught between the carrier disk 12 and the grinding wheel 11 and the grinding wheel 11 adheres to the grinding machine 10. Since the projections 50a only overlap the grinding wheel on a comparatively small area, the Grinding wheel 11 can be pulled out of the magazine with only slight deformation. Optionally, the manipulator 1 can move the grinding machine 10 in a test position in which with the aid of a sensor (for example a color sensor, see FIG Fig. 12 ) it can be tested whether a new grinding wheel has actually been attached to the grinding machine (step S7). If not, the manipulator can move the grinding machine back to the magazine (back to step S6) or cancel the process. If the grinding wheel is properly mounted, the manipulator can start a new grinding process or continue a grinding process that was previously interrupted (step S8).

Different aspects of the exemplary embodiments described here are summarized below. It should be noted that this is not an exhaustive list. One embodiment of the invention relates to a device for automatically removing a grinding wheel from a robot-assisted grinding device with a grinding machine (cf. Fig. 3 , 4th , 5 , 6th and 7th ). Accordingly, the device (detachment device 2 for detaching a grinding wheel from the carrier disk) has a frame 31, a partition plate 32 connected to the frame 31 (also referred to as "partition plate" in the figures) and a support surface connected to the frame 31. The partition plate 32 and the support surface are coupled to the frame 31 in such a way that a relative movement between the partition plate 32 and the support surface along a first direction (in or against the x-direction) is made possible. The separating plate 32 and the support surface are arranged in such a way that - when the grinding wheel rests against the supporting surface and when the separating plate 32 and the grinding wheel 11 move towards each other - a first edge K0 of the separating plate 32 is pushed over the grinding wheel (see e.g. Figure 5A , 6B or 7B ).

The partition plate 32 can be rigidly connected to the frame 31 (cf. Fig. 4 , 5 , and 6th ). The support surface can be formed by a roller conveyor 33 (see Fig. 4 and 5 ). The roller conveyor 33 can have several rollers 34 which are mounted on the frame 31. In this case, the movement of the support surface (which is defined by the rollers, so to speak) takes place in that the rollers 34 of the roller conveyor 33 rotate about their respective axes 35, which are mounted on the frame 31.

In one embodiment, the separating plate 32 and the roller conveyor 33 are designed in such a way that - when the separating plate 32 and the grinding wheel 33 move towards each other - the separating plate 32 does not yet completely cover the grinding wheel 33 when the grinding wheel 11 has left the roller conveyor 33 ( please refer Figures 5B and 5C ). The mentioned first edge K0 of the separating plate 32 is shorter than the maximum outer dimension (in the case of round grinding wheels, their diameter d ₁ ) of the grinding wheel 11 (cf. Figure 5A ). The width b (x) of the partition plate 32 transverse to the x direction can vary (see Figure 5B , arcuate contour of the partition plate 32 along the edges K1 and K2, or Figure 6B , straight contour of the partition plate 32 along the approximately tapering edges).

In one embodiment, the support surface is formed by a slide 33b, which is mounted displaceably along the x-direction relative to the frame (31) (cf. Figure 6A , Rail 33a, slide 33b). In this case, the displaceable carriage 33b takes over the function of the above-mentioned roller conveyor 33. The partition plate 32 can be rigidly connected to the frame 31.

In the embodiments according to Fig. 4-6 the device does not need its own drive. The necessary movement is brought about by the manipulator 1 that guides the grinding machine (see also Fig. 1 ). Alternatively, the support surface can be rigidly connected to the frame 31 (cf. Fig. 7 , Support surface 33 '). In this case, the device requires a separate drive 34 between the partition plate 32 and frame 31. The drive 34 is designed to move the partition plate 32 relative to the support surface 33 '.

Another exemplary embodiment relates to a device for automatically fitting a grinding machine 10, a robot-assisted grinding device, with a grinding wheel 11 (cf. Fig. 11 ). Accordingly, the device has a support 53 for receiving a stack of grinding wheels 11 and a frame (for example ring 50). The frame 50 is arranged essentially parallel to the support 53, so that the stack of grinding wheels 11 is located between the support 53 and the frame 50, the frame 50 only partially overlapping the outer edge of the top grinding wheel of the stack (e.g. with the projections 50a , please refer Fig. 12 ). The device further comprises a mechanical pretensioning unit which is coupled to the frame 50 in such a way that a defined force F _{B is} exerted by the frame on the stack of grinding wheels 11.

The mechanical pretensioning unit can have one or more guide rods 51 which are coupled to the frame 50 and run laterally next to the stack of grinding wheels and / or run through the stack of grinding wheels. For example, if the grinding wheels have holes (see e.g. Figure 2c ) the guide rods 51 can be guided through these holes.

The pretensioning unit can have a weight 55 which is coupled to the frame 50 in such a way that the weight F _{B of} the weight 55 acts on the frame 50. The guide rods 51 can be passed through openings in the support 53. In this case, the weight 55 can be connected to the guide rods 51 (and thus indirectly to the frame 50) below the support surface 53.

In one embodiment, the stack of grinding wheels is approximately cylindrical, and the frame 50 has approximately the shape of a circular ring, the inner diameter of which is larger than the outer diameter of a grinding wheel (see Fig. 12 ). The Circular ring can have one or more projections 50a on its inner circumference, which at least partially overlap the stack of grinding wheels 11.

If the angular position of the grinding machine plays a role (e.g. if the grinding wheels in the magazine have holes in certain places), the grinding machine 10 must be pressed onto the magazine of grinding wheels in the correct angular position. In this case, the device can have a camera 6 and an image processing unit 9, which is designed to determine an angular deviation of the grinding machine 10 from a target angular position. Any angular deviation that may be present can be compensated for by the manipulator.

Finally, a system for changing grinding wheels of a robot-assisted grinding device is described. According to an exemplary embodiment, the system has the following: a device with a frame 31 and a separating plate 32 for removing a grinding wheel 11 from a grinding machine (see Fig. 4 , 5 and 6th ), a manipulator 1 which is designed to position and move the grinding machine 10 relative to the separating plate 32 (see FIG Fig. 1 ). The relative movement of the grinding machine 10 and separating plate 32 during the removal of the grinding wheel is brought about exclusively by the manipulator 1 (see e.g. Fig. 4 ). The device with frame 31 and separating plate 32 for removing a grinding wheel therefore does not need its own drive. According to a further exemplary embodiment, the system additionally or alternatively has a magazine for receiving a stack of grinding wheels, a manipulator 1, which is designed to position and move the grinding machine 10 relative to the magazine, and an actuator 20, which is positioned between the grinding machine 10 and manipulator 1 is arranged and is designed to press the grinding machine 10 against the top grinding wheel of the stack of grinding wheels 11 (see FIG Fig. 11 , right figure). The relative movement between the grinding machine and the magazine is brought about exclusively by the manipulator 1 (alone) or by the manipulator 1 and the actuator 20.

The devices and systems described here enable the automatic changing of grinding wheels of a robot-assisted grinding device. One embodiment of a method relates to the automatic removal (pulling off or detachment) of a grinding wheel 11 from a robot-assisted grinding device. Accordingly, the method comprises pressing the grinding wheel against a support surface (see e.g. Figure 4A , 6A and 7A ), which is arranged essentially parallel to a separating plate 32, and executing a relative movement between the separating plate 32 and the support surface (33, 33 ', 33b), so that the separating plate 32 and grinding wheel 11 move towards each other until the separating plate 32 is in the space between Grinding wheel 11 and a carrier wheel 12 on which the grinding wheel is mounted penetrates (see Figures 4B-C , 6B-C as 7B-C ). Finally, the carrier disk 21 is lifted off the support surface, as a result of which the grinding wheel 11 is pulled off the carrier disk 32. Another method relates to the automatic mounting of a grinding wheel 11 on a robot-assisted grinding device. Accordingly, the method comprises aligning a carrier disk 12 of a grinding machine 10 by means of a manipulator 1, so that an underside of the carrier disk 12 is essentially parallel to an upper side of a stack of grinding wheels 11 (cf. Fig. 1 and 11 ). The method further comprises pressing the carrier disk 12 against the stack of grinding wheels by means of an actuator 20, which is coupled between manipulator 1 and grinding machine 10, so that the top grinding wheel of the stack of grinding wheels adheres to the carrier disk 12. Finally, the grinding machine 10 together with the grinding wheel 11 is raised by means of the manipulator 1 and / or the actuator 20 (see FIG Fig. 11 , right figure).

Claims (16)

1. A device for automatically fastening a grinding wheel on a carrier wheel of a grinding machine (10); the device includes:

   a support (53) for receiving a stack of grinding wheels;

   a frame (50), which is arranged essentially parallel to the support (53), so that the stack of grinding wheels is located between the support (53) and the frame (50), wherein the frame (50) only partially overlaps the outer edge of the uppermost grinding wheel of the stack, characterized by

   a mechanical pre-tensioning unit (51, 56, 55), which is coupled to the frame (50) so that a defined force (F_P) is exerted by the frame (50) on the stack of grinding wheels.
2. The device as claimed in claim 1, wherein the mechanical pre-tensioning unit includes a linear guide (51), which is coupled to the frame (50) in such a way that the distance between support (53) and frame (50) is variable.
3. The device as claimed in claim 1 or 2, wherein the mechanical pre-tensioning unit includes one or more guide rods (51), which are coupled to the frame (50) and extend laterally adjacent to the stack of grinding wheels and/or extend through the stack of grinding wheels, wherein the guide rods (51) are guided through openings in the support (53).
4. The device as claimed in any one of claims 1 to 3, in which the pre-tensioning unit includes a weight (55), which is coupled to the frame (50) in such a way that the weight force F_B) of the weight (55) acts on the frame (50).
5. The device as claimed in any one of claims 1 to 4,
   wherein the stack of grinding wheels is approximately cylindrical, and the frame (50) approximately has the shape of a circular ring, the internal diameter of which is larger than the external diameter of a grinding wheel (11), and
   wherein the circular ring includes one or more projections (50a) on its inner circumference, which at least partially overlap the stack of grinding wheels.
6. The device as claimed in any one of claims 1 to 5,
   wherein the frame (50) includes at least one projection (50a) which rests on the uppermost grinding wheel of the stack.
7. The device as claimed in any one of claims 1 to 6, which furthermore includes:

   a stop (39), which is designed to move an eccentric rotational axis (D1, A') of the carrier wheel into a defined reference position relative to a longitudinal axis (D2, A) of the grinding machine (10) when the carrier wheel (12) is pressed against the stop (39),

   wherein the stop (39) includes two pins or edges spaced apart from one another, against which the circumference of the carrier wheel (12) is pressed.
8. The device as claimed in any one of claims 1 to 7, which furthermore includes:

   at least one sensor (61), which is designed to detect whether the angle position of the carrier wheel (12) of the grinding machine (10) corresponds to a setpoint angle position,

   wherein the sensor (61) is a proximity sensor, a color sensor, or a camera, and

   wherein the sensor (61) is designed to detect whether a hole (H) in the carrier wheel (12) is located at a reference position.
9. The device as claimed in any one of claims 1 to 8, which furthermore includes:
   a camera and an image processing unit (9), which is designed to ascertain an angle deviation of the grinding machine (10) from a setpoint angle position.
10. The device as claimed in any one of claims 1 to 9, which furthermore includes:
    a color sensor, which is designed to detect, on the basis of a detected color, whether a grinding wheel (13) adheres to the carrier wheel (12).
11. A method for automatically installing a grinding wheel on a robot-assisted grinding device using a device as claimed in any one of claims 1 to 10, which is used as a magazine for receiving a stack of grinding wheels; the method includes:

    aligning a carrier wheel (12) of a grinding machine (10) by means of a manipulator (1) on the magazine having a stack of grinding wheels (11), so that a lower side of the carrier wheel (12) is essentially parallel to an upper side of the stack of grinding wheels (11), wherein the stack of grinding wheels is arranged between a support surface (53) and a frame (50) in the magazine, and the frame (50) only partially overlaps the outer edge of the uppermost grinding wheel of the stack;

    pressing the carrier wheel (12) against the stack of grinding wheels by means of an actuator (20), which is coupled between manipulator (1) and grinding machine (10), so that the uppermost grinding wheel of the stack of grinding wheels adheres to the carrier wheel (12);

    lifting the grinding machine (10) including grinding wheel (11) off of the stack of grinding wheels by means of the manipulator (1) and/or the actuator (20), wherein the uppermost grinding wheel of the stack is pulled out of the magazine by the frame (50).
12. The method as claimed in claim 11, which furthermore includes:
    rotating an eccentric rotational axis (D1, A') of the grinding machine into a defined reference position relative to a longitudinal axis (D2, A) of the grinding machine (10), wherein the rotation of the eccentric rotational axis (D1, A') of the grinding machine into a defined reference position is achieved in that the carrier wheel (12) is pressed on the circumference against a stop (39) by means of the manipulator (1).
13. The method as claimed in either one of claims 11 or 12, which furthermore includes:
    detecting whether the angle position of the carrier wheel corresponds to a setpoint angle position, wherein the detection comprises the following:

    positioning the grinding machine (10) by means of the manipulator (1) in such a way that a sensor (61, 6) is oriented on the carrier wheel (12) of the grinding machine (10),

    rotating the grinding machine (10) by means of the manipulator (1) until the sensor (61, 6) detects the setpoint angle position, wherein the sensor (61) is a proximity sensor or a color sensor.
14. The method as claimed in any one of claims 11 to 13, which furthermore includes:

    ascertaining an angle deviation of the grinding machine (10) from a setpoint angle position by means of image processing;

    correcting the angle deviation with the aid of the manipulator (1) .
15. The method as claimed in any one of claims 11 to 14, which includes the following after the lifting of the grinding machine (10) :
    checking by means of a sensor (63) whether a grinding wheel (11) actually adheres to the carrier wheel (12), wherein the sensor (63) is a color sensor which detects the color of the carrier wheel (12) or the grinding wheel (11).
16. A system for changing grinding wheels of a robot-assisted grinding device, which includes:

    a device for automatically fastening a grinding wheel on a carrier wheel of a grinding machine (10) as claimed in any one of claims 1 to 10;

    a manipulator (1), which is designed to position and move the grinding machine (10) relative to the stack of grinding wheels;

    wherein the relative movement between the grinding machine (10) and the stack of grinding wheels is effectuated exclusively by the manipulator (1) or by the manipulator (1) and the actuator (20).

Images