Device for surface machining by robot assistance

Abstract

Relax the requirements for precision of the robot's movements. [Solution] An apparatus comprising: a support plate (51), a motor (31), a linear actuator (2), a machining head (33; 33a, 33b) coupled to the support plate (51) by the linear actuator (2), the machining head (33; 33a, 33b) having a drive shaft for directly or indirectly driving a rotatable tool (32), and a flexible shaft (544) connecting a motor shaft (310) of the motor (31) and the drive shaft of the machining head (33; 33a, 33b).

Description

Technical Field

[0001] The present invention relates to the field of robotics, and more particularly, to an apparatus for robot-assisted machining of a workpiece surface.

Background Art

[0002] In surface machining assisted by a robot, a machine tool such as a grinding machine or a polishing machine (for example, an electric grinding machine using a grinding disk rotating as a grinding tool) is guided by a manipulator such as an industrial robot. Here, the machine tool can be coupled to the TCP (Tool Center Point) of the manipulator in various ways. Usually, the manipulator can freely adjust the position and posture of the machine tool and move the machine tool on an orbit parallel to the surface of the workpiece. An industrial robot is usually position-controlled and can accurately move the TCP along a target orbit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to obtain good results in grinding with robot assistance, control of the machining force (grinding force) is required for many uses, but it may be difficult to control with sufficient accuracy with conventional industrial robots. The large and heavy arm part of the industrial robot has too much inertia, and the controller (closed-loop controller) cannot quickly respond to fluctuations in processing power. To solve this problem, an actuator that is smaller (lighter) for industrial robots and couples the TCP of the manipulator to the machine tool can be arranged between the TCP of the manipulator and the machine tool. During surface machining, the linear actuator only controls the machining force (the contact force between the tool and the workpiece), while the manipulator moves the machine tool and the linear actuator by position control along a desired trajectory. By force control, the linear actuator can correct inaccuracies in the position and shape of the workpiece to be machined and inaccuracies in the trajectory of the manipulator (within a certain range). However, if the robot does not apply the grinding tool tangentially to the surface of the workpiece, problems may occur in the machining results.

[0005] The inventor has developed an improved apparatus for surface machining with robot assistance and a corresponding process, and in particular, has made it an object to relax the requirements for the accuracy of the operations performed by the robot.

Means for Solving the Problems

[0006] The above problems are solved by the apparatus according to claim 1. Different embodiments and further developments are the subject of the dependent claims.

[0007] One embodiment of the present invention relates to an apparatus for surface treatment with robot assistance. The apparatus of this embodiment has a support plate for attachment to a manipulator, a motor, a linear actuator, and a processing head. The processing head is coupled to the support plate by the linear actuator and includes a drive shaft for directly or indirectly driving a rotatable tool. The apparatus further has a flexible shaft that couples the motor shaft of the motor and the drive shaft of the processing head. The support plate does not necessarily have to be attached to the manipulator and may be fixed as part of a support such as a housing or a tripod.

[0008] The apparatus further includes a universal joint that mechanically couples the processing head and the linear actuator so as to enable two-axis tilting of the processing head.

Advantages of the Invention

[0009] The requirements for the accuracy of the operations performed by the robot can be relaxed.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in more detail with reference to the examples shown in the figures. The figures are not necessarily to scale, and the present invention is not limited to the illustrated aspects. Rather, emphasis is placed on explaining the principles underlying the present invention.

[0012] Before explaining various embodiments of the present invention in detail, first, a general example of a grinding device with robot assistance will be described. Also, the concepts described here are applicable to other types of surface finishing (e.g., polishing) and are not limited to grinding. Hereinafter, embodiments will be described by taking a grinding machine equipped with a rotating grinding tool (grinding disk) as an example. However, the concepts described here are not limited to this, and can also be applied to other machine tools such as a tool that moves in a circular motion (belt grinding device), or a tool that vibrates or oscillates (vibratory grinding device).

[0013] As shown in FIG. 1, this device is composed of a manipulator 1 such as an industrial robot and a grinding machine 3 (e.g., an orbital grinding machine) equipped with a rotating grinding tool. And the grinding machine 3is coupled to the so-called Tool-Center-Point (TCP) of the manipulator 1 via the linear actuator 20. Strictly speaking, the TCP is not a point but a vector and can be described, for example, by three spatial coordinates and three angles. In robotics, the generalized coordinates of the configuration space (usually the six joint angles of the robot) are used to represent the position of the TCP. The position and orientation of the TCP are also referred to as the "pose". The position (including orientation) of the TCP as a function of time defines the movement, which is the trajectory of the grinding tool.

[0014] Also, in the case of an industrial robot having six degrees of freedom, the manipulator has joints G 13 、G 12 、G 11 and can be composed of four segments 14、13、12、11 connected by. The first segment 11 is usually fixedly connected to the base 10 (this does not necessarily have to be the case). Joint G 11 connects segment 11 and segment 12. Joint G 11 can be biaxial, and segment 12 may be able to rotate about a horizontal axis of rotation (elevation angle) and a vertical axis of rotation (azimuth angle). Joint G 12 connects segment 13 and segment 12 and enables the swivel movement of segment 13 with respect to the position of segment 2c. Joint G 13 connects segment 14 and segment 14. Joint G 13 can be biaxial, and thus (joint G 11Similarly, it enables rotational movement in two directions. The TCP has a fixed relative position with respect to segment 14, and segment 14 usually enables the rotational movement of end effector 15 arranged on segment 14 around the longitudinal axis A of segment 14 (which also corresponds to the rotation axis of the grinding tool in this example, as shown by the dotted line in FIG. 1) and includes a rotational joint (not shown). An actuator (for example, an electric motor) is assigned to each axis of the joint, and these actuators can cause rotational movement around the axis of each joint. The actuators of the joint are controlled by robot control unit 4 according to a robot program. Various industrial robots / manipulators and related controls are known, and no further explanation will be given here.

[0015] Manipulator 1 is usually position-controlled, that is, the robot control unit can determine the posture (position and orientation) of the TCP and move the TCP along a predefined trajectory. In FIG. 1, the longitudinal axis of segment 14 where the TCP is arranged is denoted as A. When actuator 2 is at the end stop, the posture of the TCP also defines the posture of grinding machine 10 (and grinding disk 11). As described at the beginning, actuator 2 sets the contact force (processing force) between the tool and workpiece 5 to a desired value during grinding. Direct force control by manipulator 1 is usually too inaccurate for grinding applications. This is because due to the high mass inertia of segments 11 - 14 of manipulator 1, rapid correction of force peaks (for example, when placing the grinding tool on workpiece 5) is substantially impossible with conventional manipulators. For this reason, robot control unit 4 is configured to control the posture (position and orientation) of the TCP of manipulator 1, and force control is solely performed by actuator 2.

[0016] As already described, during the grinding process, the contact force F between the grinding tool (grinding machine 3 having grinding disk 32) and workpiece 5 K is the contact force F (in the direction of longitudinal axis A) between grinding disk 32 and workpiece 5K It can be set by the linear actuator 2 and force control (which can be realized, for example, in the control unit 4) so as to correspond to a predetermined value. The contact force F at that time K is the reaction to the actuator force F with which the linear actuator 2 presses the surface of the workpiece. A When there is no contact between the workpiece 5 and the tool, the actuator 2 moves to an end stopper (not shown because it is integrated with the actuator 2) due to the lack of the contact force on the workpiece 5 and presses the end stopper with a predetermined force. At this time, the force control is active throughout. Therefore, in this situation (non-contact), the displacement of the actuator 2 becomes maximum and the actuator is located at the end. The defined force with which the actuator 2 presses the end stopper can be adjusted to be very small or (theoretically) zero in order to make the contact with the workpiece surface as gentle as possible.

[0017] The position control of the manipulator 1 (which can also be realized by the control unit 4) can be executed completely independently of the force control of the actuator 2. The actuator 2 is not used for positioning the grinding machine 3, but only for setting and maintaining the desired contact force F K during the grinding process and for detecting the contact between the tool 32 and the workpiece 5. This contact is easily recognized, for example, by the actuator moving from the end position (the displacement a of the actuator is smaller than the maximum displacement a MAX at the end).

[0018] The actuator 2 may be a pneumatic actuator, for example, a double-acting pneumatic cylinder. However, it is also possible to use other pneumatic actuators, such as bellows cylinders or air muscles. As an alternative, an electric direct drive (gearless) is also conceivable. Note that the acting direction of the actuator 2 and the rotational axis of the grinding machine 3 do not necessarily coincide with the longitudinal axis A of the segment 14 of the manipulator 1. In the case of a pneumatic actuator, force control can be realized in a manner known per se by means of a control valve, a control device (for example, implemented in the control unit 4), and a compressed air accumulator or compressor. Since the inclination with respect to the vertical direction is important in order to take into account gravity (i.e., the weight force of the grinding machine 3), the actuator 2 may include an inclination sensor or this information can be derived from the joint angles of the manipulator. The detected inclination is taken into account during force control. However, since the specific implementation of force control is known per se, a detailed description is omitted.

[0019] The grinding machine 3 usually comprises an electric motor for driving the grinding disk 32. In orbital grinding machines - and in other types of grinding machines as well - the grinding disk 32 is attached to a support plate (backing pad), to which the motor shaft of the electric motor is connected. As the electric motor, an asynchronous motor or a synchronous motor is conceivable. Synchronous motors have the advantage that the speed does not change with the load (only the slip angle), while in an asynchronous machine, the speed decreases as the load increases. The load on the motor basically depends on the contact force F K and is proportional to the friction between the grinding disk 32 and the surface of the workpiece 5 to be machined.

[0020] Instead of an electrically driven grinding machine, a grinding machine equipped with a pneumatic motor (compressed air motor) can also be used. Since a compressed air motor usually has a low output-to-weight ratio, a grinding machine operating with compressed air can be made relatively compact. Rotation control can be easily achieved by a pressure control valve (optionally or alternatively also by a throttle), which is (for example, electrically controlled by the control unit 4), but a frequency converter (for example, electrically controlled by the control unit 4) for rotation control is required for synchronous and asynchronous motors. The concepts described here can be realized in various types of grinding machines, polishing machines, and other machines for surface finishing.

[0021] In particular, in the case of a grinding machine equipped with an electric motor, the electric motor can occupy a significant part of the weight. In the following example, the actuator 2 is used not only to mechanically disconnect the manipulator 1 from the workpiece but also to mechanically disconnect the motor of the grinding machine from the working head to which the grinding disk is attached. In the case of a grinding machine, the processing head is called the grinding head. Furthermore, in some of the following embodiments, an inaccurate positioning of the grinding machine relative to the surface of the workpiece can be corrected (within a certain range), reducing the effort required to create a robot program.

[0022] According to the example shown in FIG. 2, the machine tool 3 has a first support plate 51 and a second support plate 52. The first support plate 51 is configured to be attached to the manipulator 1, for example, to the end effector flange 15 of the manipulator 1 in FIG. 1. A grinding head 33, which will be described in detail later, is attached to the second support plate 52. During operation, the grinding disk 32 can be attached to the rotatable support plate 35 (backing pad) of the grinding head 33. A linear actuator 2 is disposed between the two support plates 51 and 52. Since the linear actuator 2 acts between the two support plates 51 and 52, the distance a between the two support plates 51 and 52 will depend on the displacement of the linear actuator 2. In normal operation, the linear actuator 2 operates with force control as described above, and is configured such that the force of the actuator acts between the two support plates 51 and 52. When the tool 32 is not in contact with the surface, the linear actuator 2 presses an end stopper (not shown) of the actuator 2 with a target actuator force. The actuator 2 can be a pneumatic linear actuator, for example, including a double-acting pneumatic cylinder. However, it is also possible to use other actuators. Here, the support plates 51 and 52 do not necessarily have to be flat plates, and can be any support structure or a part of such a support structure. Also, the support plates 51 and 52 do not necessarily have to be a single integral body, and can be composed of a plurality of parts.

[0023] The grinding head 33 (grinding head, sanding head) can be regarded as a grinding machine substantially without a drive unit (motor). The grinding head 33 includes a drive shaft (rotating shaft C) that directly or indirectly drives the support plate 35 on which the grinding disk 32 is disposed. Also, the grinding head 33 may include a gear that eccentrically rotates the support plate 35, as is common in an orbital grinder. Examples of grinding heads are shown, for example, in the publication of EP 0237854 A2 (Patent Document 1) (corresponding to US 4759152), and thus no further description will be given here.

[0024] According to this embodiment, a motor 31 (for example, an electric motor) for driving the support disk 35 of the grinding head 33 is attached to the first support plate 51. According to the example of FIG. 2, the motor 31 is attached to the first support plate 51, and the motor shaft 310 penetrates the first support plate 51. The distance between the two support plates 51 and 52 is "bridged" by the flexible shaft 544 and the telescopic shaft 54, where the telescopic shaft 54 is optional. That is, the motor shaft 310 is connected to the drive shaft (rotation axis C) of the grinding head 33 via the flexible shaft 544 to drive the drive shaft. Further, so that the flexible shaft 544 does not bend too much, the motor shaft 310 is coupled to one end of the telescopic shaft 54 (shaft coupling 53a), and the other end of the telescopic shaft 54 can be coupled to the flexible shaft 544 (shaft coupling 53b). The flexible shaft 544 drives the drive shaft (rotation axis C) of the grinding head 33 directly or via the transmission device 34 as shown in FIG. 2. The input shaft of the transmission device 34 has the rotation axis indicated by B in FIG. 2. The flexible shaft 544 is flexible (that is, the longitudinal axis of the shaft is curved with a variable curvature), and is different from a conventional cardan shaft in which two or more fixed shaft portions are connected by (cardan) joints.

[0025] The telescopic shaft 54 is composed of two relatively displaceable shaft portions (hollow shaft / sleeve 541, displaceable shaft 543). The first portion of the two shaft portions is coupled to the motor shaft 33 of the motor 31 (for example, by a shaft coupling 53a), and the second portion of the two shaft portions is coupled to the flexible shaft 544 (for example, by a shaft coupling 53b).

[0026] The second shaft 543 of the telescopic shaft 54 is displaceable relative to the first shaft portion (hollow shaft 541) along the rotation axis of the telescopic shaft 54. For this reason, the hollow shaft 541 (the first shaft portion) may include a linear guide 542 that can displace the second shaft 543 along the rotation axis of the telescopic shaft 54. As described above, the telescopic shaft 54 has an arbitrary configuration. When the telescopic shaft is not used, depending on the application, the flexible shaft 544 may receive a greater bending stress than when the telescopic shaft 54 is also used.

[0027] In the example shown in FIG. 2, the grinding head 33 is attached to the support plate 52 by a universal joint 60, and two-axis inclined movement of the grinding head 33 (relative to the support plate 52) is possible. The first inclination axis K 1 and the second inclination axis K 2 By tilting about, two-axis tilting movement becomes possible. FIG. 3 shows the lower part of the apparatus of FIG. 2 (the support plate 52 provided with the universal joint 60 and the grinding head 33), and the grinding head 33 is tilted about the inclination axis K 1 . FIG. 4 shows a side view X of the lower part of the apparatus of FIG. 2. In FIG. 4(a), the grinding head 33 is in the normal position, and in FIG. 4(b), the grinding head 33 is tilted about the inclination axis K 2 . The universal joint can be supported by two lateral legs 521, 522 of the support plate 52. Since the universal joint as a gimbal suspension is known per se, a detailed description thereof is omitted here.

[0028] Here, when the grinding head 33 tilts, the rotation axes B and C also tilt (see FIG. 2). However, the tilts of the rotation axes B and C are compensated by corresponding bending of the flexible shaft 544. Further, the inclination axes K 1 , K 2 (the normal state where it is not tilted) are in a plane below the plane where the lower end of the flexible shaft is located. The inclination axes K 1 , K2 The vertical distance between and the lower end of the flexible shaft 544 is d in FIG. 2 V as shown. Further, the lower end of the flexible shaft 544 is coaxial with the rotation axis B and is horizontally spaced from the rotation axis C of the grinding tool (horizontal distance d H ). Generally, the universal joint 60 is arranged as close as possible to the grinding disk 32 so that the inclination axes K 1 , K 2 are as low as possible.

[0029] In the embodiment shown in FIGS. 5 and 6, a grinding apparatus is shown in which the grinding disk 32 rotates about a rotation axis C that is not coaxial with the motor shaft 310 (rotation axis A'). In the illustrated example, the rotation axis A' of the motor shaft 310 is perpendicular to the horizontal plane in which the rotation axis C of the grinding disk 32 lies. In this case, the flexible shaft 544 that connects the motor shaft 310 and the drive shaft (rotation axis C) of the grinding head 33 is bent by approximately 90°. Also, in order to reduce the maximum amount of bending of the flexible shaft 544, in this case, a telescopic shaft can also be arranged between the motor shaft 310 and the flexible shaft 544 (see FIG. 2).

[0030] The actuator 2 couples the grinding head 33 to the upper support plate 51. The distance a between the rotation axis C of the grinding disk 32 and the support plate 51 depends on the displacement of the actuator 2. In this case, the lower support plate 52 (see FIG. 2) is not necessary (due to the configuration of the grinding head 53). FIG 5 shows the apparatus in a state where the actuator 2 is displaced maximally (distance a = a MAX ), and the displacement of the actuator in this state is limited by an end stopper. FIG. 6 shows a small displacement of the actuator 2 (a < a MAX)The apparatus is shown. Note that the support plate 51 does not necessarily have to be mounted on the manipulator and can also be fixedly supported in place. In this case, for example, the relative positioning of the workpiece with respect to the machining tool 32 can be performed using a manipulator. Regarding this point, the example of FIG. 9 is referred to.

[0031] FIGS. 7 and 8 show a further example of an embodiment including a plurality of grinding heads 33a, 33b that can be tilted about two axes, similar to the example of FIG. 2. The upper part (support plate 51, motor 31, actuator 2) of the apparatus shown in FIG. 7 is the same as in the examples of FIGS. 2 and 6, and the above description is referred to. However, the apparatus of FIG. 7 has an assembly 70 including two or more grinding heads 33a, 33b instead of a single grinding head 33. The entire assembly 70 is coupled to the actuator 2 by a universal joint 60. In the example shown in FIG. 7, one end of the universal joint 60 is attached to the support plate 52, and this support plate 52 is firmly connected to the lower end of the actuator 2. The other end of the universal joint 60 is attached to the housing 71 of the assembly 70. Also, in this embodiment, the intersection of the tilt axes of the universal joint 60 is at a vertical distance d V from the lower end of the flexible shaft 544, and in this embodiment, it is preferable to arrange the universal joint 60 as low as possible. Different from the example of FIG. 2, when there are a plurality of grinding heads, since it is possible to arrange the universal joint 60 between the grinding heads, the joint can have a simpler design and a gimbal suspension as in FIG. 2 is not necessary.

[0032] A plurality of grinding heads 33a, 33b are arranged within the housing 71 such that a rotatable support plate 35a or 35b projects from the bottom of the housing 71 of the assembly 70. In the present embodiment, the rotational axes of the drive shafts of the grinding heads 33a, 33b are respectively designated as C and D. A pulley 73a is attached to the drive shaft of the grinding head 33a, and a pulley 73b is attached to the drive shaft of the grinding head 33b. In a special embodiment, a third grinding head 33c (not shown in FIGS. 7 and 8) is provided with a pulley 73c, and the rotational axes of the three grinding heads are each offset by 120° with respect to the longitudinal axis A of the actuator 2. It should be noted that it is also possible to use other transmission devices (such as toothed gears) instead of the belt drive. In the embodiments described herein, a transmission device such as a belt drive is used to transmit mechanical power. How this mechanical power transmission is specifically carried out is not particularly important.

[0033] Another shaft (rotational axis B) is attached to the housing 71 of the assembly 70 (see FIG. 7, bearing 72), and this shaft is connected to the motor shaft 310 by a flexible shaft 544. Another pulley 74 is attached to the shaft having the rotational axis B, and a belt 75 connects the pulley 74 (driven by the motor 31 via the flexible shaft 544) and the pulleys 73a, 73b (and optionally 73c) such that the drive shafts of all the grinding heads 33a, 33b (and optionally 33c) are driven via the belt. (As shown in FIG. 7, when in the normal non-inclined position) the vertical distance a between the assembly 70 and the upper support plate 51 depends on the displacement of the actuator 2. Both the change in the distance a and the inclination of the assembly 70 can be compensated for by the flexible shaft 544. FIG. 8 shows the case where the assembly 70 is inclined in the apparatus of FIG. 7.

[0034] FIG. 9 shows another embodiment when the device is not mounted on the manipulator but is fixed in place and used. In this case, the workpiece can be positioned relative to the grinding disk using the manipulator. According to FIG. 9, the support plate 51 is attached so as to be fixed in place. In this example, the support plate 51 may be considered as part of any support structure (which applies to all embodiments) and may be attached to any support structure. Examples of the support structure include a housing or a tripod. The support plate 51 can also be regarded as part of the actuator 2 (which also applies to all embodiments). Similar to the example in FIG. 5, the actuator 2 directly or indirectly couples the support plate 51 to the machining head 33 (grinding head). In the simplest case, it includes a shaft to which a machining tool such as the grinding disk 32 is rotatably attached. In the machining process, the workpiece 5 is positioned (e.g., by a manipulator), and the actuator 2 either reliably controls the contact force as described above or presses against the end stopper with a defined force (a force set by force control) when there is no contact with the workpiece.

[0035] In the embodiment of FIG. 9, the motor 31 is also attached in a stationary position (e.g., to the same support structure as the actuator 2), and although its relative position to the grinding head 33 varies, this can be compensated via a flexible shaft 544 (similar to the other embodiments described here). It should be noted that in the above-described embodiments where the (at least one) grinding head is tiltably attached to the actuator using a gimbal suspension or a universal joint, it is also possible to operate in a stationary state when positioning the workpiece using the manipulator.

[0036] In the following, some aspects of the embodiments described herein are summarized, which are merely exemplary and not a complete summary of the relevant technical features. The present embodiment relates to an apparatus for a robot to assist in surface machining. According to a general embodiment, the apparatus includes a support plate (see, for example, FIGS. 2, 5, and 7, support plate 51) for attaching the apparatus to a manipulator, a motor, a linear actuator, and at least one machining head (see, for example, FIGS. 2, 5, grinding head 33, or FIGS. 7, grinding heads 33a, 33b). The machining head is coupled (directly or indirectly) to the support plate by a linear actuator and includes a drive shaft (see, for example, the rotation axis B in FIG. 2, the rotation axis C in FIGS. 5 and 7) for directly or indirectly driving a rotatable tool. The apparatus further includes a flexible shaft that directly or indirectly couples the motor shaft of the motor and the drive shaft of the machining head (for example, via an additional telescopic shaft).

[0037] As described above, the support plate does not necessarily have to be mounted on the manipulator. Alternatively, the workpiece to be machined can be placed by the manipulator, in which case the support plate is fixed in a place such as part of a housing, a tripod, or other support structure. The motor can be attached to the same support plate as the actuator. However, this is not necessary when a flexible shaft is employed. As already mentioned, the support plate does not necessarily have to be a flat plate and can be any support structure.

[0038] In some embodiments, a universal joint is used to mechanically couple the (at least one) machining head to the linear actuator. In this case, the two-axis inclination of the machining head becomes possible. In the embodiments of FIGS. 2 to 4, the universal joint is realized by a Cardan suspension, while in the embodiments of FIGS. 7 and 8, a simple universal joint (Cardan joint) is used. Depending on the application, it is also possible to replace the universal joint with a single-axis joint so that it can be inclined only about one inclination axis.

[0039] According to the embodiment of the present case, the device has a support structure attached to one end of a linear actuator, while the other end of the linear actuator is attached to a support plate. As described above, the universal joint forms a Cardan suspension, whereby the machining head can be attached to the support structure. In the simplest case, the support structure can be another support plate (see, for example, FIGS. 2 to 4, the base plate 52 having laterally provided legs 521, 522). The support structure may have openings for passing the machining head and the flexible shaft (in FIG. 3, the grinding disk 32 is below the support plate 52 and the flexible shaft is above the support plate 52, respectively, and are coupled to the grinding head 33). The two inclined axes of the universal joint are spaced from above the machining head (FIG. 2, distance d V ) and pass through the machining head. Thereby, since the inclined axis becomes relatively close to the workpiece, it is possible to prevent the machining head from tilting and catching an edge during the grinding process. In the example of FIG. 2, the two inclined axes and one rotational axis of the machining head intersect at one point. The machining head has a transmission device (see FIG. 3, transmission device 34), and the axial directions of the rotational axis of the rotatable tool and the rotational axis of the drive shaft are offset (FIG. 2, distance d H reference).

[0040] In some embodiments, a plurality of machining heads are attached to a support structure, which is coupled to a linear actuator via a universal joint. This is the case, for example, in the embodiment of FIG. 7 where the support structure is formed by the housing 71 of the assembly 70. The universal joint allows tilting about two tilting axes, which may intersect at an intersection point that, according to a particular embodiment, also passes through the longitudinal axis of the actuator. The universal joint is disposed within the housing of the assembly, and the plurality of grinding heads are disposed around the universal joint. For example, three grinding heads can be arranged offset by 120° (with respect to the longitudinal axes of the actuator and the joint) around the universal joint. The tilting axes of the universal joint lie in a plane passing through the grinding head and are located as close as possible to the surface of the workpiece.

[0041] A shaft is attached to the support structure (e.g., housing 71, see FIG. 7) by bearings, and this shaft is connected to a flexible shaft so that it can be driven by a motor. This shaft is connected to the drive shaft of the grinding head via a transmission such as a belt drive.

[0042] Generally, the flexible shaft allows the motor to be coupled to the grinding head even if the relative position of the grinding head with respect to the motor varies. The change in relative position can be compensated for by the flexible shaft. The motor axis and the rotation axis of the grinding head do not have to be parallel and can have an angle of about 90° (see FIG. 5). To avoid excessive bending of the flexible shaft, the flexible shaft can be combined with a telescopic shaft (see FIG. 2).

Description of Reference Numerals

[0043] 2... Linear actuator 31... Motor 32... Tool 33, 33a, 33b... Machining heads 34…Transmission device 51…Support plate 52…Support structure 60…Universal joint 71…Support structure 72…Bearing 310…Motor shaft 544…Flexible shaft A…Longitudinal axis A´…Axis of rotation B, C…Axes of rotation K 1 、K 2 …Axis of inclination

Claims

1. A support plate (51) mounted on an arm of a manipulator of a grinding device with robot assistance, a motor (31) supported by the support plate (51), a processing head (33; 33a, 33b) having a drive shaft for directly or indirectly driving a rotatable tool (32), a linear actuator (2) that connects the processing head (33; 33a, 33b) to the support plate (51) and executes force control of the processing head (33; 33a, 33b), a flexible shaft (544) that connects the motor shaft (310) of the motor (31) and the drive shaft of the processing head (33; 33a, 33b), a joint (60) that mechanically connects the processing head (33; 33a, 33b) and the linear actuator (2) so as to enable tilting of the processing head (33; 33a, 33b) in one axial direction or two axial directions, and a device having the same.

2. The joint (60) is a universal joint that mechanically connects the processing head (33; 33a, 33b) and the linear actuator (2) so as to enable tilting of the processing head (33; 33a, 33b) in two axial directions, or the device according to claim 1 having the universal joint.

3. further comprising a first support structure (52) connected to one end of the linear actuator (2), the other end of the linear actuator (2) is connected to the support plate (51), The device according to claim 2, wherein the universal joint (60) forms a Cardan suspension, whereby the processing head (33) is supported by the first support structure (52).

4. The universal joint (60) extends through the machining head (33) at an interval (d V ) from above the machining head (33), and the device according to claim 3, which is tiltable about two inclined axes (K １ , K ２ ).

5. The first support structure (52) has a base plate and two opposing legs (521, 522), The device according to claim 3 or claim 4, wherein the processing head (33) is attached to the two legs (521, 522) via the Cardan suspension.

6. The device according to claim 5, wherein the first support structure has an opening through which the processing head (33) or the flexible shaft (544) passes.

7. The apparatus according to any one of claims 1 to 6, wherein the machining head (33) has a transmission device (34), and the rotation axis (C) of the rotatable tool (32) and the rotation axis (B) of the drive shaft are offset.

8. further comprising a second support structure (71) connected to one end of the linear actuator (2) via the universal joint (60), the other end of the linear actuator (2) being connected to the support plate (51), The apparatus according to claim 2, wherein one or more machining heads (33a, 33b) are attached to the second support structure (71).

9. The universal joint (60) is tiltable about two tilt axes (K １ , K ２ ), and the tilt axes (K １ , K ２ ) intersect at an intersection point that also passes through the longitudinal axis (A) of the linear actuator (2). The device according to claim 8.

10. The apparatus according to claim 8 or 9, wherein two or more machining heads (33a, 33b) are attached to the second support structure (71), and the machining heads (33a, 33b) are arranged around the universal joint (60).

11. The tilt axis (K １ , K ２ ) is in a plane extending through the machining head. The apparatus according to claim 9

12. A shaft is attached to the second support structure (71) via a bearing (72), and the shaft is connected to a flexible shaft (544) and drives the drive shaft of the machining head (33a, 33b) via a transmission device. The apparatus according to any one of claims 8 to 11.

13. The apparatus according to claim 12, wherein the transmission device is a belt drive or a gear drive.

14. The apparatus according to any one of claims 1 to 13, wherein the motor shaft (310) of the motor (31) and the drive shaft of the machining head (33; 33a, 33b) are coupled to each other via the flexible shaft (544) and a telescopic shaft.

15. The apparatus according to any one of claims 1 to 14, wherein the machining head (33; 33a, 33b) has a backing pad that supports a grinding disk.

16. The apparatus according to any one of claims 1 to 14, wherein the machining head (33; 33a, 33b) has a backing pad that supports a grinding disk, and a drive unit that connects the drive shaft of the machining head to the backing pad and eccentrically rotates the backing pad.

17. a support plate mounted on an arm of a manipulator of a grinding apparatus with robot assistance, a motor supported by the support plate, At least one processing head having a drive shaft for directly or indirectly driving a rotatable tool, a linear actuator that connects the at least one processing head to the support plate and performs force control of the at least one processing head, a flexible shaft that connects the motor shaft of the motor and the drive shaft of each of the at least one processing head, a universal joint that mechanically couples the at least one processing head and the linear actuator such that the at least one processing head is tiltable about two tilt axes that intersect at an intersection point through which the longitudinal axis of the linear actuator also passes, a support structure connected to one end of the linear actuator via the universal joint, the other end of the linear actuator being connected to the support plate, and the support structure to which the at least one processing head is attached, An apparatus having the above.

18. A support plate mounted on an arm of a manipulator of a grinding apparatus with robot assistance, a motor supported by the support plate, a processing head having a drive shaft for directly or indirectly driving a rotatable tool, a linear actuator that connects the processing head to the support plate and performs force control of the processing head, a flexible shaft that connects the motor shaft of the motor and the drive shaft of the processing head, a universal joint that mechanically couples the processing head and the linear actuator to enable tilting of the processing head in two axial directions, An apparatus having the above, wherein the universal joint enables tilting about two tilt axes that extend through the processing head at a distance from above the processing head.

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