Changing station for automatic abrasive material change

Abstract

To automatically replace a grinding disk in a relatively simple and reliable manner. [Solution] The present invention discloses a replacement station configuration for automatically replacing abrasives (grinding discs) in a robot-assisted grinding device, and a method for loading abrasives into a grinding machine and removing worn abrasives from the grinding machine.

Description

[Technical Field]

[0001] The present invention relates to a change station that allows automated changing of abrasive material, such as abrasive fleece discs (non-woven abrasive material), for a robot-assisted grinding device. [Background technology]

[0002] Grinding machines, such as orbital grinding machines, are used in a variety of industrial and craft applications. In orbital grinding machines, a rotational movement around the axis of rotation is superimposed on an oscillation. Orbital grinding machines are often used for final surface processing, where high demands are placed on the surface quality. To meet these demands, irregularities in the grinding process must be avoided as much as possible. In practice, these tasks are usually carried out by experienced craftsmen, especially in small-scale production.

[0003] In robot-assisted surface processing, a grinding tool, such as an orbital grinding machine, is guided by a manipulator, e.g., an industrial robot. The grinding tool and the so-called end effector of the manipulator can be coupled in various ways. The end effector's orientation is fixedly coupled to the TCP (Tool Center Point), allowing the manipulator to position the machine tool virtually freely. Industrial robots are usually position-controlled and can precisely move the TCP along a desired trajectory. To achieve good results in robot-assisted grinding, many applications require control of the grinding force. This is often difficult to achieve with sufficient precision using conventional industrial robots. The large and heavy arm segments of industrial robots have too much inertia, preventing their controllers (closed-loop controllers) from reacting quickly enough to fluctuations in the process force. To solve this problem, a linear actuator, smaller than that used in industrial robots, can be placed between the manipulator's end effector and the work tool, which can couple the manipulator's end effector and the work tool. The manipulator is position controlled and together with the linear actuator moves the grinding tool along a predefinable trajectory, while the linear actuator controls only the machining force (contact force between the tool and the workpiece).

[0004] Robot-assisted grinding uses an exchange station where the robot can automatically exchange abrasive materials (such as grinding discs). The exchange station typically consists of an extraction unit that can be used to remove worn abrasive discs from the support plate (backing pad) of the grinding machine, and a magazine with new abrasive discs. The magazine is configured so that the robot can remove new abrasive discs from the magazine and attach them to the support plate. In many applications, the abrasive discs are fixed to the support plate using hook-and-loop fasteners (e.g., Velcro).

[0005] Changing stations for the automatic change of abrasives are usually specially designed for a particular type of abrasive. Grinding discs made of abrasive fleece, also known as nonwoven abrasives, are used in many grinding processes. In contrast to grinding discs made of abrasive paper, grinding discs made of abrasive fleece are significantly thicker and softer, which affects the conditions required for the change process (e.g., fleece tears more easily than paper). Although several robot-assisted changing station concepts exist for changing abrasive discs, known solutions are relatively complex, expensive to implement, and therefore expensive. Worn abrasive discs are often changed manually, even in robot-assisted grinding processes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US 8517799 B2 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, one of the basic objectives of the present invention is to provide a removal unit and a magazine that allows for the automatic replacement of abrasive discs (especially relatively thick and soft abrasive discs such as abrasive fleece discs) in a robot-assisted grinding device in a relatively simple and reliable manner. [Means for solving the problem]

[0008] The above problem is solved by a device and a method according to the independent claims. Different embodiments and further developments are the subject of the dependent claims.

[0009] A method for removing abrasive material from a robot-assisted grinding machine is described below. The method of an embodiment includes the steps of: positioning the grinding machine on a curved support element of an unloading device near a clamping mechanism of the unloading device using a manipulator; clamping the abrasive material by closing the clamping mechanism; performing a rolling motion of the grinding machine using the manipulator while the abrasive material is in contact with the curved support element to partially remove the abrasive material from the support plate of the grinding machine; retracting the grinding machine using the manipulator to completely remove the abrasive material from the support plate; and releasing the clamping mechanism.

[0010] Furthermore, a method for automatically loading abrasive material prepared in a magazine onto a support plate of a robot-assisted grinding machine is described. The method of this embodiment includes the steps of: using a linear actuator to press the abrasive material (e.g., the top abrasive material in a stack of abrasives) against the back side of a retaining ring, where the linear actuator is force-controlled to press the abrasive material against the retaining ring with a predetermined contact pressure; using a manipulator to position the grinding machine above the magazine and press the support plate of the grinding machine against the front side of the retaining ring to adhere the abrasive material to the support plate; reducing the contact pressure from a first value to a second value less than the first value; and using the manipulator to retract the grinding machine from the magazine and pull the abrasive material adhered to the support plate through the retaining ring and out of the magazine. After the grinding machine is retracted, the contact pressure can be increased again to the initial value.

[0011] The removing device and the device with the magazine can be combined to form a changing station for automatic changing of the abrasive material. According to an embodiment, the removing device for removing the abrasive material from a robot-assisted grinding machine has a curved support element for the abrasive material mounted on a support plate of the grinding machine, and a clamping mechanism configured to clamp the abrasive material in a clamping direction by closing the clamping mechanism while the abrasive material is placed on the curved support element at an angle to the clamping direction.

[0012] According to an embodiment, an apparatus for automatically loading abrasive material prepared in a magazine onto a support plate of a robot-assisted grinding machine includes: a magazine containing a stack of abrasive material and having a retaining ring; a linear actuator configured to press the stack of abrasive material against the retaining ring; and a control device for the linear actuator configured to initially set the contact pressure when the abrasive material is pressed against the retaining ring to a predetermined first value, and the control device is configured to reduce the contact pressure from the first value to a second value less than the first value while the stack of abrasive material continues to be pressed against the retaining ring so that the abrasive material at the top of the stack can be easily removed. [Effects of the Invention]

[0013] In a robot-assisted grinding device, it becomes possible to automatically change abrasive discs (especially relatively thick and soft abrasive discs such as abrasive fleece discs) in a relatively simple and reliable manner. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating an example of a robot-assisted grinding device.

[0015] [Figure 2] 1 is a diagram showing a grinding tool and a grinding disc, and the attachment of the grinding disc to the grinding tool;

[0016] [Figure 3] 10A-10C illustrate further examples of robot-assisted grinding devices.

[0017] [Figure 4] FIG. 1 shows an example of a magazine that allows automatic loading of abrasive discs onto a grinding machine.

[0018] [Figure 5] 5A and 5B are diagrams showing an example of a retaining ring of the magazine of FIG. 4.

[0019] [Figure 6] 10A and 10B are diagrams illustrating an example of a process for automatically loading a grinding disc from a magazine onto a grinding machine.

[0020] [Figure 7] 10A and 10B are diagrams illustrating an example of a process for automatically loading a grinding disc from a magazine onto a grinding machine.

[0021] [Figure 8] 10 is a flowchart illustrating an example of automatic loading of a grinding disk from a magazine onto a grinding machine.

[0022] [Figure 9] 9 is a flowchart illustrating an example of a partial aspect of the process of FIG. 8.

[0023] [Figure 10] 1 shows a removal device for automatically removing a grinding disc from a support plate of a grinding machine;

[0024] [Figure 11] 1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0025] [Figure 12]1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0026] [Figure 13] 1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0027] [Figure 14] 1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0028] [Figure 15] 1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0029] [Figure 16] 1 shows intermediate steps of an unloading device for automatically unloading a grinding disc from a support plate of a grinding machine;

[0030] [Figure 17] 10 is a flow chart illustrating an example of automatic removal of a grinding disc.

[0031] [Figure 18] FIG. 11 illustrates a modification / extension of the example shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0032] Various embodiments will now be described in more detail using illustrative examples, which are not necessarily to scale and are not intended to limit the invention to the illustrated embodiments, but rather to illustrate the principles underlying the invention.

[0033] Before describing various embodiments of the present invention in detail, we will first describe an example of a robot-assisted grinding machine. It includes a manipulator 1, such as an industrial robot, and a grinding machine 10 (e.g., an orbital grinding machine) equipped with a rotating grinding tool, connected to the end effector and thus the TCP of the manipulator 1 via a linear actuator 20. In the case of an industrial robot with six degrees of freedom, the manipulator is composed of four segments 2a, 2b, 2c, and 2d, each connected via joints 3a, 3b, and 3c (see FIG. 1). The first segment 2d is typically (but not necessarily) rigidly connected to the base 41. Joint 3c connects segments 2c and 2d. Joint 3c can be biaxial, allowing segment 2c to rotate about a horizontal axis of rotation (elevation) and a vertical axis of rotation (azimuth). Joint 3b connects segments 2b and 2c, allowing segment 2b to pivot relative to the orientation of segment 2c. Joint 3a connects segments 2a and 2b. Joint 3a can be biaxial and therefore allows for bidirectional pivoting (as does joint 3c). Segment 2a forms the end effector and therefore has a fixed relative position to the TCP. Segment 2a also typically has a revolute joint (not shown), allowing for rotational movement around the longitudinal axis of segment 2a (shown as a dotted line in Figure 1 and corresponding to the axis of rotation of the grinding tool). Each axis of the joint is assigned an actuator that allows for rotational movement around the respective axis of rotation. The joint actuators are controlled by the robot controller 4 according to the robot program.

[0034] The manipulator 1 is typically position-controlled. That is, the robot controller determines the pose (position and orientation) of the TCP and moves it along a predefined trajectory. When the actuator 20 contacts the end stop, the pose of the grinding tool is also defined as the pose of the TCP. As already mentioned at the beginning, the actuator 20 is used to set the desired contact force (processing force) between the tool (grinding machine 10) and the workpiece 40 during the grinding process. Direct force control by the manipulator 1 is generally too inaccurate for grinding applications. This is because the large inertia of the manipulator's segments 2a-c makes rapid correction of force peaks (e.g., when the grinding tool is placed on the workpiece 40) virtually impossible with conventional manipulators. For this reason, the robot controller controls the pose of the manipulator's TCP, while force control is exclusively achieved by the actuator 20.

[0035] As already mentioned, during the grinding process, the contact force F between the tool (grinding machine 10) and the workpiece 40 KThe contact force between the grinding tool and the workpiece 40 can be set by the (linear) actuator 20 and force control (which can be implemented, for example, in the robot controller 4) so ​​that it corresponds to a predeterminable set value. The contact force is the reaction of the actuator force with which the linear actuator 20 presses against the workpiece surface (to which the weight of the grinding machine is added). If there is no contact between the workpiece 40 and the tool, the actuator 20 moves toward the 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 robot controller 4) can operate completely independently from the force control of the actuator 20. The actuator 20 is not involved in positioning the grinding machine 10; it is only involved in setting and maintaining the desired contact force during the grinding process and 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, such as bellows cylinders or air muscles, can also be used. An electric direct drive (gearless electric drive) is also conceivable as an alternative.

[0036] In the case of pneumatic actuators, the force control can be realized in a manner known per se by means of control valves, a control device (implemented in the robot control unit 4) and a compressed air accumulator. However, the specific implementation method is not important for further explanation and will not be described in further detail.

[0037] The grinding machine 10 includes an abrasive disc 11 attached to a support disc 12. The front surface of the support disc 12 and / or the back surface of the abrasive disc 11 are configured to allow the abrasive disc 11 to easily adhere to the support disc 12 upon contact. For example, a hook-and-loop fastener may be used to attach the abrasive disc 11 to the support disc. A detachable adhesive connection, a detachable snap-in connection, or the like may also be used.

[0038] FIG. 2(a) shows a grinding machine 10 equipped with an abrasive disc 11. During operation, the support disc 12 is driven by the grinding machine's 10 electric motor, causing the abrasive disc 11 to rotate together with the support disc 12 (rotation axis A). In the case of an orbital grinding machine, the support disc 12 performs a more complex movement, i.e., rotation around two parallel rotation axes with a defined axial offset. The abrasive disc 11 is made of, for example, abrasive fleece, is flexible (i.e., bendable), and can be removed from the support disc. FIG. 2(b) shows the grinding machine 10 with the abrasive disc 11 removed. FIG. 2(c) shows a side view of the abrasive disc 11 and a view of the abrasive disc 11 from below (in the direction of rotation axis A).

[0039] FIG. 3 shows a further example of a grinding machine 10 mounted on an actuator 20. The actuator 20 has a first flange 21 that can be rigidly connected to the manipulator 1 (e.g., the end effector 2a in FIG. 1). The end of the actuator 20 opposite the flange 21 is provided with a second flange (hidden in FIG. 3) to which the grinding machine 10 is attached. FIG. 3 also shows a hose connection 15 for, for example, a suction device that can remove grinding dust. However, grinding dust removal is optional. Note that fleece grinding discs are usually much thicker than those shown in FIG. 3.

[0040] Despite the automation of the grinding process using robot-assisted grinding machines, replacing abrasive discs is still often performed manually by an operator grasping the end of the abrasive disc 11 with their thumb and index finger and pulling it off the support disc. Existing automated solutions for automatically replacing abrasive discs are relatively complex, resulting, for example, from the fact that the abrasive disc 11 must be grasped by a mechanical device before removal. The embodiments described herein offer particular advantages for thick, flexible abrasive discs (e.g., made of abrasive fleece). Next, we first describe a grinding disc magazine that allows for the automatic loading of (new) abrasive discs into a robot-guided grinding machine. The corresponding procedure is then described. This is followed by a description of a removal device and a corresponding method that allows for the automatic removal of abrasive discs from the support disc of a grinding machine.

[0041] FIG. 4 shows an example of a magazine 5 that allows for automatic loading of abrasive discs 11 into a grinding machine 10. The magazine 5 has a frame or housing 50. In the illustrated example, a support plate 53 is slidably mounted within the housing. A stack of abrasive discs 11 is disposed on the support plate 53 within the housing 50. The support plate 53 is connected to a linear actuator 51, which is configured to push the support plate 53 upward together with the stack of abrasive discs. In the illustrated example, the actuator 51 is disposed below the support plate 53 within the housing 50. The actuator 51 can be a pneumatic actuator, such as a pneumatic cylinder. However, other types of linear actuators, such as a bellows cylinder or an electric direct drive, can also be used. The actuator 51 can also include a combination of an active drive and a (passive) spring.

[0042] In the illustrated example, a retaining ring 52 is disposed on the upper side of the housing 50, and an actuator 51 is configured to press the stack of grinding discs 11 against the underside of the retaining ring 52. The actuator force F with which the linear actuator 51 presses the top grinding disc against the retaining ring 52 is A For this purpose, the actuator 51 is connected to a control unit 59 that can adjust the force that the actuator exerts on the support plate 53. The method and purpose of the force control by the control unit 59 will be explained in detail later.

[0043] 5 is a diagram illustrating an example of a retaining ring 52 of the magazine 5 of FIG. 4. The maximum inner diameter of the retaining ring 52 is labeled R1, and the outer diameter of the abrasive disc 11 is labeled R2. The inner diameter R1 of the retaining ring 52 is greater than the outer diameter R2 of the stack of abrasive discs (R1>R2). To prevent the actuator 51 from pushing the abrasive discs out of the magazine, the retaining ring 52 has one or more protrusions 52a-d that protrude (overlap) onto the edge of the top abrasive disc in the stack. That is, the protrusions 52a-d are directed inward (toward the center of the retaining ring 52).

[0044] The actuator 51 is force-controlled by the control unit 59, i.e. the force with which the top grinding disc is pressed with its backside facing upwards against the projections 52a-d of the retaining ring 52 is adjustable (e.g. 50 Newtons). In the case of a pneumatic actuator, the force control can be realized in a known manner by means of a control valve (not shown), a controller (implemented in the control unit 59) and a compressed air reservoir (not shown). The specific implementation of the force control is known per se and is not important for further explanation, so will not be further described here.

[0045] FIG. 4 shows the magazine 5 filled with grinding discs in an initial state, in which the actuator 51 applies a defined (controlled) force F A =F A1, which presses the stack of abrasive discs upward against the retaining ring 52. During magazine operation (after loading with abrasive discs), the top (highest) abrasive disc in the stack abuts against the retaining ring 52, i.e. the stack of abrasive discs does not drop between two successive loading steps and the magazine 5 remains ready for use without the need to lift the abrasive disc stack before each loading step (loading step).

[0046] At the start of the loading process, the robot positions the grinding machine 10 above the magazine so that the support plate 12 of the grinding discs is substantially coaxial with the stack of grinding discs. In other words, the support plate 12 of the grinding machine 10 is positioned centrally above the stack of grinding discs and substantially parallel to the retaining ring 52, and then pressed with a small force against the upper side of the retaining ring. When the stack of grinding discs is actively pushed upward (by the actuator 51), the backside of the top grinding disc 11 contacts the underside of the support plate 12. As a result, the backside of the top grinding disc 11 adheres to the underside of the support plate 12. This is because the two corresponding surfaces are made of a material that, together, forms, for example, a hook-and-loop fastener. As mentioned above, other connection means can also be used.

[0047] Particularly when using hook-and-loop fasteners, it may be advantageous for the robot to move the support plate 12 slightly back and forth parallel to the retaining ring 52 while the support plate 12 is in contact with the top grinding disc. This slight movement causes the loops and hooks of the hook-and-loop fasteners to tightly engage (hook together). This situation is shown in Figure 6. The arrows indicate the actuator force F of the actuator 51. A , showing the pressing of the grinding machine against the top side of the retaining ring 52 and the lateral movement mentioned above.

[0048] In the mounting process shown in Figure 6, the actuator force F A1must be relatively large so that the top (highest) abrasive disc in the stack "sticks" upward from the retaining ring 52, ensuring good adhesion of the abrasive disc 11 to the support disc. Pressing the abrasive disc stack clamps the top abrasive disc of the stack to the underside of the retaining ring 52 (on the protrusions 52a-d, see FIG. 5). This clamping can cause the connection between the support plate 12 and the abrasive disc 11 to be broken again when the grinding machine 10 is lifted from the magazine, resulting in a failed loading process. Some systems lower the abrasive disc stack after the loading process to release the aforementioned clamping. However, this lowering has the disadvantage that the abrasive discs rub along their circumference against the inside of the frame / housing 50 or other components within the housing, leading to wear. However, according to the embodiment described herein, the actuator 51 operates in a force-controlled manner, so that the actuator force F is applied before the grinding machine is lifted from the magazine. A F A1 From F A0 (F A0 <F A1 ), which significantly reduces the clamping effect and allows the abrasive discs to simply be "pulled" out of the magazine 5 without lowering the abrasive disc stack (i.e., the abrasive disc stack is still in contact with the underside of the retaining ring). The actuator force F A is the set value F A1 and the magazine is immediately ready for the next loading process. This state is shown in Figure 7. The support plate 53 is only lowered (i.e. the force control is switched off or the actuator force is reduced to zero) in order to fill the magazine 5 with new grinding discs.

[0049] The above process is summarized below with reference to the flow chart of Figure 8. The stack of grinding discs in the magazine 4 is subjected to a defined force F A18, step S1), and the magazine is ready for a new loading process. The robot positions the grinding machine 10 above the magazine 5 (approximately coaxial with the retaining ring 52) (FIG. 8, step S2). Finally, the support plate of the grinding machine (e.g., by the actuator 20, see FIG. 3) is pressed against the retaining ring 52 (FIG. 8, step S3), and the top abrasive disc of the stack is attached to the support plate, for example, by a hook-and-loop fastener. Before the grinding machine 10 is lifted from the magazine, the control unit 59 (see FIG. 4) calculates the actuator force F generated by the actuator 51. A 1) indicating that the force F should be reduced, so that the actuator 51 reduces the force F exerted on the stack of grinding discs. A1 From F A0 (FIG. 8, step S4). Thereafter, the grinding machine 10 is lifted from the magazine 5, and the attached grinding disc is pulled out from the magazine (FIG. 8, step S5).

[0050] FIG. 9 illustrates a further embodiment of the concept described herein for improving the accuracy of force control by taking into account the weight of the abrasive disc stack. First, actuator 51 presses the abrasive disc stack against the backside of retaining ring 52 (FIG. 9, step S1.1). The actuator deflection (actuator position) varies depending on the number of abrasive discs in the magazine. The fewer abrasive discs in the stack, the more upward actuator 51 must deflect support plate 53. The actuator deflection can be measured, and based on the measured actuator deflection, controller 59 can calculate the weight of the abrasive disc stack (FIG. 9, step S1.2). For example, the number of abrasive discs in the magazine can be calculated from the actuator deflection and the known thickness of the abrasive discs. Because the weight of each individual abrasive disc is known, the total weight of the abrasive disc stack can be determined from the calculated number of abrasive discs. Alternatively, the density (weight per unit of stack height) of the abrasive disc material (e.g. abrasive fleece) can be stored in the control, allowing the control 59 to simply calculate the weight of the stack currently in the magazine from the density and the actuator deflection. The weight of the stack is then determined by the actuator force F A This is taken into consideration when setting (Figure 9, step S1.2).

[0051] For example, if the determined weight of the stack of grinding discs is 10 Newtons, the actuator force F A is set to 40 Newtons (target force + weight) to effectively press the top grinding disc against the retaining ring 52 with 30 Newtons. This allows the actuator force (particularly the value F A0 For example, if the gravitational force is only 2 Newtons, then the actuator force F must be 30 Newtons to keep the upper grinding disk pressed against the retaining ring 52. A must be reduced to 32 Newtons. If weight is not taken into account, the force may be too great.

[0052] FIG. 10 illustrates a removal device 6 for automatically removing a grinding disc from a support plate of a grinding machine. In the illustrated example, the removal device includes a housing 60 with a clamping mechanism 62. The housing 60 does not necessarily have to be enclosed and can also be formed as a frame (open housing), etc. The clamping mechanism 62 is formed by clamping jaws 622, 623 that are displaceable (slidable) relative to each other in a clamping direction (schematically indicated in FIG. 10 by a dashed arrow labeled "CLAMP"). The clamping jaw 623 is part of a plate arranged on the upper side of the housing 60, and the clamping jaw 622 is mounted in or on the housing so as to be displaceable in the clamping direction (e.g., by a linear guide) and is movable by a linear actuator 61. That is, the linear actuator 61 is configured to close and release the clamping mechanism (along the clamping direction). The clamping edge of the clamping jaw 622 (to the left of the clamping jaw 622 in FIG. 10) is aligned with the corresponding edge of the clamping jaw 623 in the clamping direction. The actuator 61 can be any linear actuator, such as a pneumatic cylinder or an electric linear actuator.

[0053] A support element 64 is arranged on the side of the housing 60 where the clamping jaws 622, 623 are located. This support element 64 has a convexly curved outer contour on its outer side (the side facing away from the housing). The clamping device 62 is opened before the removal process. The robot positions the grinding machine with the (worn) grinding disc 11 obliquely in front of the support element 64 (e.g., relative to the vertical clamping direction) and then presses the grinding disc against a part of the curved surface of the support element 64. The orientation of the grinding machine 10 is also indicated in FIG. 10 by an arrow (labeled "positioning"). In the illustrated example, the rotation axis of the grinding machine is at an angle of approximately 45° relative to the clamping direction. It is understood that the clamping direction does not necessarily extend along the vertical direction, and that the grinding machine is inclined relative to the clamping direction. In the situation shown in FIG. 10, the actuator 61 closes the clamping device 62 to clamp the grinding disc 11 at one end.

[0054] The actuator may have a sensor (e.g., an end position switch) for detecting an end position. If the actuator 61 moves to an end position when the clamping mechanism is closed, this indicates that the abrasive disc 11 is not properly clamped between the clamping jaws 622 and 623. In the situation shown in Figure 11, the abrasive disc 11 is properly clamped between the clamping jaws 622 and 623, and therefore the actuator 61 has not reached its end position. Except for the closed clamping mechanism 62, Figure 11 is identical to Figure 10.

[0055] The tilted grinding machine solves some of the problems that can arise with known concepts. According to a known method (see US 8517799 B2), a separating plate is inserted between the support plate 12 and the grinding disc 11 parallel to the surface of the support plate 12 to release the abrasive disc. However, this method is only effective if the thickness of the abrasive disc is known, as is the case with sandpaper. However, the thickness of the abrasive disc is not always the same and can vary significantly (especially in the case of relatively thick discs made of abrasive fleece, which thin with wear, resulting in significantly different thicknesses of the worn disc). According to another method, the (worn) abrasive disc is pressed against a flat support surface (parallel to the support plate 12) and clamped against it with clamping jaws. In this case, the clamping direction is parallel to the rotation axis of the grinding machine (not oblique). This method is only effective if the abrasive disc is slightly larger than the support plate. This is the case when using petal-shaped abrasive discs (so-called daisy discs).

[0056] The concept described here works reliably even if the actual thickness of the grinding disc is unknown and the grinding disc does not extend beyond the support plate. The grinding disc can also have a diameter slightly smaller than the grinding machine's support plate 12. As can be easily seen from Figure 11, even if the grinding disc 11 is not larger (or even slightly smaller) than the support plate 12 to which it is attached, the tilted condition will cause the lower edge (on the circumference of the grinding disc) to be located between the clamping jaws 622 and 623.

[0057] Starting from the situation shown in Figure 11, the robot moves the grinding machine 10 so that the support plate 12 performs a rolling motion on the convexly curved surface of the support element 64, while the actuator 20 presses the support plate 12 (with a weak force) against the support surface 64. During the rolling motion, the grinding machine 10 is rotated (rolled) away from the clamping mechanism. The aforementioned rolling motion is shown in several intermediate steps in Figures 12, 13, 14, and 15. This rolling motion reduces the pulling force of the grinding disc in the clamping area and prevents the grinding disc 11 from being torn off from the clamping mechanism 62 before it has completely separated from the support plate 12.

[0058] As seen in Figures 12, 13, 14, and 15, during the rolling process, the flexible abrasive disc 11 contacts the curved surface of the support surface 64, resulting in a relatively high frictional force (similar to wrapping a rope around a bollard) that prevents the load from being fully transferred to the clamping mechanism as the abrasive disc is removed. This ensures that the abrasive disc 11 is not torn off the clamping device 62 during the removal process. During the rolling operation of the grinding machine, the abrasive disc 11 gradually peels away from the support plate 12 (e.g., the hook-and-loop fastener is released). Figure 15 shows the end of the rolling operation, with only a small portion of the abrasive disc 11 remaining attached to the support plate.

[0059] Starting from the state shown in Figure 15, the robot can pull back the grinding machine 10 so that the support plate 12 is clear of the surface of the support element 64, thereby releasing the part of the grinding disc 11 that is still attached from the support plate 12. The actuator 61 can then be activated to open the clamping mechanism 62 again and allow the grinding disc 11 to fall (e.g. into a collection container). The signal to close and clamp the clamping device can be generated, for example, by the robot control (see Figure 1, robot control 4).

[0060] The removal process is summarized below using the flowchart shown in FIG. 17. According to FIG. 17, the robot positions the grinding machine 10 with the grinding disc 11 on the convexly curved support element 64 on the clamping mechanism 62 (FIG. 17, step R1). The grinding machine 10 is positioned obliquely relative to the clamping direction of the clamping mechanism 62, allowing the circumferential edge of the grinding disc 11 to be clamped by the clamping device 62. The edge of the grinding disc 62 is then clamped (FIG. 17, step R2, the clamping mechanism is activated). The robot then controls the rolling movement of the grinding machine 10 on the support element 64 while the support plate 12 is pressed against the surface of the curved support element 64 (FIG. 17, step R3). Finally, the robot retracts the grinding machine 10 from the support element 64 (FIG. 17, step R4), thereby finally separating the grinding machine 11 from the support plate 12. The clamping mechanism 62 is then released (FIG. 17, step R5) and the grinding disc 11 can be dropped (eg, from the removal device to a collection container).

[0061] It should be noted that a replacement station can be formed by combining the removal device according to FIG. 10 with the magazine according to FIG. 4. From the above description, a person skilled in the art can supplement or modify the described embodiment to create further embodiments without changing the underlying concept of the embodiment. For example, the removal device according to FIG. 10 can be mounted so that it can slide (displace) in one direction (e.g., horizontally) and secured by a spring, so that the removal device can slide (displace) against the spring force when the robot places the grinding machine with the grinding disc on the convexly curved support element. This situation is shown in FIG. 18, which is a modified / extended version of the example of FIG. 10. In general, the manipulator positions the grinding machine so that the edge of the support plate 12 is as close as possible to the clamping device (but only the abrasive fleece protrudes into the clamping device), so that when the clamping device closes, the clamping jaws 622 and 623 grip the abrasive fleece as close as possible to the edge of the support plate 12 (see FIG. 18, distance a is as small as possible, theoretically zero).

[0062] The magazine of FIG. 4 can also be mounted to allow vertical displacement (sliding) against the biasing force of a spring, so that the entire magazine yields when the robot loads the grinding machine with its support plate onto the magazine. This configuration is advantageous when the grinding machine is directly connected to the robot's end effector (no actuator 20). Depending on the application, actuator 20 (see FIG. 1) may be unnecessary or replaced with a passive spring. After removing the grinding disc from the support plate, optical inspection (e.g., using a camera) can be performed to confirm that the grinding disc has indeed been completely removed. Optical inspection can also be used to verify that the grinding disc is properly attached to the support plate after the loading process.

[0063] Finally, polishing is considered a special case of grinding, so that everything said in relation to a grinding machine or grinding process applies equally to abrasive machines and processes. [Explanation of symbols]

[0064] 1...Manipulator 5...Magazine 6...Removal device 10...Grinding machine 11... Grinding disc, abrasive material 12...Support plate 51...Linear actuator 52...Retaining ring 53...Support plate 62...Clamping mechanism 64...Support element

Claims

1. A method for removing abrasive material (11) from a robotically assisted grinding machine (10), comprising the steps of: positioning said grinding machine (10) on a curved support element (64) of said removal device (6) near a clamping mechanism (62) of said removal device (6) by means of a manipulator (1); clamping the abrasive material (11) by closing the clamping mechanism (62); performing a rolling movement of the grinding machine (10) by the manipulator (1) while the abrasive (10) is in contact with the curved support element (64) to partially remove the abrasive (11) from the support plate (12) of the grinding machine (10); Pulling back the grinding machine (10) by the manipulator (1) to completely remove the abrasive material (11) from the support plate (12); Releasing the clamping mechanism (62); A method having the following.

2. 2. The method of claim 1, wherein the step of positioning the grinding machine (10) on the curved support element (64) is performed such that the rotation axis of the grinding machine (12) is inclined relative to the clamping direction of the clamping mechanism (62).

3. 3. The method of claim 2, wherein the inclination of the rotation axis of the grinding machine (12) relative to the clamping direction of the clamping mechanism (62) is in the range of 30 to 60 degrees.

4. 4. The method of claim 1, wherein the clamping mechanism (62) closes vertically and the grinding machine is positioned obliquely relative to the vertical.

5. 5. The method according to claim 1, wherein the grinding machine (10) is positioned such that an end of the support plate (12) is positioned as close as possible to the clamping mechanism (62) and the abrasive (11) protrudes into the clamping mechanism (62).

6. 6. The method according to claim 1, wherein the support element (64) is convexly curved and the abrasive material (11) is clamped between the support element (64) and the support plate (12) during the rolling movement, with the abrasive material (11) held on one side by the clamping mechanism.

7. 7. Method according to any one of claims 1 to 6, characterized in that the removal device (6) is arranged so as to be linearly displaceable, in particular horizontally displaceable, against the action of a spring force.

8. A method for automatically loading abrasive material (11) prepared in a magazine (5) onto a support plate (12) of a robot-assisted grinding machine (10), comprising: A process of pressing the abrasive (11) against the back side of the retaining ring (52) by a linear actuator (51), wherein the linear actuator (51) is force-controlled to press the abrasive (11) against the retaining ring (52) with a predetermined contact pressure (F Ａ =F Ａ１ ) pressing the a step of positioning the grinding machine (10) above the magazine (5) using a manipulator (1) and pressing a support plate (12) of the grinding machine (10) against the front side of the retaining ring (52) to attach the abrasive material (11) to the support plate (12); The contact pressure is changed from a first value to a second value (F Ａ =F Ａ０ ) and a step of pulling back the grinding machine (10) from the magazine by the manipulator (1) and pulling out the abrasive material (11) attached to the support plate (12) from the magazine by penetrating the retaining ring (52); A method having the following.

9. After the grinding machine (10) is withdrawn, the contact pressure is increased to the first value (F Ａ =F Ａ１ 9. The method of claim 8, wherein the concentration of hydroxyl group is increased to 100 ppm.

10. 10. A method according to claim 8 or claim 9, wherein the abrasive material (11) is attached to the support plate by an adhesive layer, magnetically or by hook and loop fasteners.

11. 11. The method according to claim 8, wherein the grinding machine (10) performs a swinging movement parallel to the retaining ring (52) by means of the manipulator (1) while the support plate (12) is pressed against the retaining ring (52).

12. 12. A method according to any one of claims 8 to 11, wherein the abrasive (11) is the uppermost abrasive of a stack of abrasives arranged in a magazine on a support plate (53).

13. 13. The method of claim 12, wherein the linear actuator (51) pushes the support plate (53) upward toward the retaining ring (52) and does not cycle the raising and lowering of the abrasive stack during operation.

14. A removal device (6) for removing abrasive material (11) from a robot-assisted grinding machine (10), comprising: a curved support element (64) for the abrasive material (11) mounted on a support plate (12) of the grinding machine (10); a clamping mechanism (62) configured to clamp the abrasive material (11) in the clamping direction by closing the clamping mechanism (62) while the abrasive material (11) is placed on the curved support element (64) at an angle to the clamping direction; A removal device (6) having

15. 1. An apparatus for automatically loading abrasive material (11) prepared in a magazine (5) onto a support plate (12) of a robot-assisted grinding machine (10), comprising: said magazine (5) containing a stack of abrasive material (11) and having a retaining ring (52); a linear actuator (51) configured to press the stack of abrasive material (11) against the retaining ring (52); The control unit (59) of the linear actuator controls the contact pressure when the abrasive (11) is pressed against the retaining ring (52) to a predetermined first value (F Ａ =F Ａ１ a control device (59) configured to set the and The control unit (59) controls the contact pressure to decrease from the first value to a second value (F) less than the first value while the stack of abrasive material (11) continues to be pressed against the retaining ring (52) to allow easy removal of the abrasive material at the top of the stack. Ａ =F Ａ０ ) to reduce the

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