Method and device for braking relative movement, and coordinate measuring machine

Abstract

The invention relates to a method and a device for braking a relative movement between two parts of a coordinate measuring machine that can be moved relative to one another, having a device for braking the relative movement, comprising at least one piezoelectric element (6) for generating a braking force, in which a target braking force is determined, a voltage assigned to the target braking force is applied to the piezoelectric element (6), and the invention also relates to a coordinate measuring machine.

Description

Technical Field

[0001] The invention relates to a method and a device for braking a relative movement between two parts of a coordinate measuring machine that are movable relative to each other, in particular for braking a rotating axis element, and the invention also relates to a coordinate measuring machine. Background Art

[0002] In the case of a coordinate measuring machine, at least one sensor for measuring a measurement or test object can be moved relative to the measurement or test object. This movement can be generated at least in part by the rotation of a rotary axis element or by the linear movement of a linear axis element, which is driven by a corresponding drive device (e.g., a motor).

[0003] In the case of a coordinate measuring machine, high rigidity may be desirable for specific measurement tasks. In this regard, it is desirable, for example, that the kinematic structure of the coordinate measuring machine have a higher rigidity than that of a specific tactile sensor. High rigidity is also desirable in the case of heavy sensors, as it minimizes gravity-induced bending of the structure. This, in turn, leads to a desired high positioning accuracy. Furthermore, especially when the sensor is required to be stationary, energy consumption for maintaining the sensor's position can be minimized, as correction for positional deviations caused by bending is not required. Furthermore, it is desirable that external loads on the coordinate measuring machine only minimally alter its structure, so that, in particular, the calibration performed remains valid.

[0004] In particular, when stationary, the desired high positioning accuracy can also be achieved, in particular by virtue of the fact that the shaft element moved to move the sensor is reliably braked and no longer performs a rotational movement in the braked state. Ideally, this reliable braking should also be ensured independently of the load, especially in the case of heavy sensors.

[0005] The prior art discloses solutions using gear mechanisms with high transmission ratios, which can provide high speed reduction on the output side. However, these solutions introduce design complexity and can cause positional changes in the shaft elements due to mechanical stresses during braking. In the case of coordinate measuring machines, this can lead to measurement errors.

[0006] Friction brakes are also known, including, for example, coils with permanent magnets. A disadvantage of these friction brakes is the large installation space required. Friction brakes, which require electrical current to set the brake to the open position, also disadvantageously cause a thermal load on the surrounding environment, as these friction brakes can heat up significantly when in the open position. Furthermore, when these brakes are closed, impacts can be applied to the axis element being braked, leading to undesired movement. In the case of coordinate measuring machines, this can also cause measurement errors.

[0007] So-called locking brakes with an electrically actuated drive are also known, typically comprising an electric motor and a transmission element (e.g., in the form of a spindle). Disadvantageously, these locking brakes also require a high level of installation space. Furthermore, these brakes are heavy and generally do not allow for continuous adjustment of the final applied braking force.

[0008] Another disadvantage of locking brakes, especially those with electrically actuated drives, is their limited dynamic range. Therefore, in some cases, a certain dead time may elapse before the desired braking force is reached, which is disadvantageous in terms of control engineering.

[0009] Likewise, the aforementioned solutions have the disadvantages of a generally high installation space requirement and the heavy weight of the brake system. Furthermore, during operation, the described brake system emits an undesirably large amount of thermal energy into the surrounding environment. This can lead to thermally induced deformations of the coordinate measuring machine's structure, which in turn can adversely affect measurement accuracy.

[0010] Likewise, piezoelectric locking brakes are known. These use so-called piezoelectric actuators. In particular, such piezoelectric actuators can be used to brake linear axis elements, but also for braking rotary axis elements.

[0011] Known from the prior art is US Pat. No. 8,534,429 B2, which discloses a braking system for a stepper motor having a piezoelectric actuator. This document discloses a disk fixed to the output shaft of the stepper motor, wherein a brake element exerts a braking force on the disk. The document does not describe the characteristics of the disk.

[0012] Also known is US 2023 / 0005502 A1, which describes a data storage device. This document describes that piezoelectric elements can actuate arms that can exert a clamping force on vertical guide pins in order to brake linear movement.

[0013] DE 100 02 699 B4 discloses a braking device for mutually braking and / or locking two components of a fluid-actuated drive that are movable relative to one another. Specifically, it discloses a piezoelectric actuator that can exert a braking force on the movable component via a braking surface arrangement. An embodiment is also described in which the braking surface arrangement cooperates with the movable component over its entire outer circumference during the braking process. In this case, the braking surface arrangement can surround the movable component like a collar.

[0014] Also known is US Pat. No. 9,582,046 B2, which discloses a brake arrangement comprising a ring segment and legs, between which a piezoelectric disc is arranged. When the piezoelectric disc expands, the ring is positioned around the pin and exerts a friction force on it.

[0015] EP 3 696 495 A1 describes a sensor having a brake element. The brake element may include a piezoelectric actuator. The piezoelectric actuator can exert a braking force on a shaft element via a first brake element.

[0016] Also known is EP 0 472 058 B1, which includes a punching device having a piezoelectric element.

[0017] The use of piezoelectric braking devices in coordinate measuring machines is unknown. A disadvantage of all the described solutions based on piezoelectric elements is that, due to their design, the braking devices can exert forces on the rotating axis element to be braked in the axial and / or radial directions of the element both during the braking process (i.e., during the generation of the braking force) and in the unbraked state. However, as a result, the position of the rotating axis element can undesirably change in this direction, both during the braking process and during the at least partially unbraked state. This is particularly undesirable when the rotating axis element is used to move or position sensors in coordinate measuring machines, where high position accuracy is required. Summary of the Invention

[0018] The technical problem is therefore to provide a method and a device for braking relative movement between two parts of a coordinate measuring machine that are movable relative to one another, as well as a coordinate measuring machine, which method, device, and coordinate measuring machine allow for reliable braking of the relative movement while simultaneously reducing the installation space requirement and the thermal load on the surrounding environment (in particular, other components of the coordinate measuring machine). Specifically, the technical problem is to ensure high position accuracy of the rotary axis elements of the coordinate measuring machine, in particular with respect to position changes along and transversely to the axis of rotation. Furthermore, it is also desirable to provide such a device with low energy consumption. Furthermore, it is desirable to be able to achieve a particularly continuous setting of the braking force, in particular for position control mode.

[0019] The solution to the technical problem is evident from the subject matter having the features of the independent claims. Further advantageous configurations of the invention are evident from the dependent claims.

[0020] A method for braking a relative movement between two parts of a coordinate measuring machine that are movable relative to each other is proposed.

[0021] Coordinate measuring machines are used to measure a measurement object. In this case, the coordinate measuring machine may include at least one sensor (particularly a tactile or optical sensor) or an interface for attaching such a sensor. For measurement purposes, the sensor or interface and the measurement object may need to be moved relative to one another. Furthermore, the coordinate measuring machine may include at least one axis element (particularly a rotary or linear axis element), wherein movement of the axis element may generate at least a portion of the interpreted relative movement.

[0022] Furthermore, the coordinate measuring machine may include at least one drive device for generating a driving force / torque for moving the axis element. Preferably, the coordinate measuring machine includes multiple axis elements, in particular multiple rotary axis elements and / or multiple linear axis elements. Similarly, the coordinate measuring machine preferably includes multiple drive devices. In this case, these axis elements may be mechanically coupled to one another in such a manner that a desired relative movement within a predetermined measurement volume is achieved.

[0023] Parts of a coordinate measuring machine that are movable relative to one another can be coupled to one another via at least one such shaft element. In this respect, one of the movable parts can be fixed to the shaft element, wherein the shaft element is mounted in a movable manner (in particular, rotationally or linearly movable) on the other part.

[0024] Coordinate measuring machines with a gantry or gantry design are known. Such coordinate measuring machines include parts that are movable relative to one another and are configured to enable linear movement of a sensor along at least one spatial direction (preferably along each axis of a Cartesian coordinate system). The sensor can be fixed to one of the parts. Alternatively or cumulatively, such a coordinate measuring machine can also be configured to enable rotational movement of the sensor about at least one rotational axis (preferably about each axis of a Cartesian coordinate system). The sensor can be fixed to one of the parts. In this regard, the coordinate measuring machine can include, for example, a rotary pivot joint that enables rotational movement of the sensor about at least two mutually different rotational axes. The vertical axis (z-axis) of the Cartesian coordinate system can be oriented parallel to and opposite to the direction of gravity. The longitudinal and transverse axes (x-axis and y-axis) of the Cartesian coordinate system can each be oriented perpendicular to the vertical axis and also perpendicular to each other. This Cartesian coordinate system can form a reference coordinate system.

[0025] The coordinate measuring machine includes at least one device for braking relative movement (braking device), the at least one device comprising at least one piezoelectric element for generating a braking force. A piezoelectric element may also be referred to as a piezoelectric actuator. Preferably, the piezoelectric element is configured as a piezoelectric stack actuator, in particular as a non-amplified piezoelectric stack actuator or as an amplified piezoelectric actuator. Such a stack actuator may include a plurality of piezoelectric layers arranged adjacent to one another along a stacking direction.

[0026] The dimensions of the piezoelectric element (particularly its length, width, or thickness) vary depending on the voltage applied to the piezoelectric element. Specifically, the piezoelectric element can expand or contract depending on the applied voltage. As a result, the piezoelectric element can also generate a force, hereinafter referred to as piezoelectric force, depending on the applied voltage. The dimensional variation of the piezoelectric element can be relatively small and lie in the micrometer or millimeter range, for example, less than 300 mm, less than 200 mm, less than 100 mm, or less than 1 mm. In embodiments as stacked actuators, this dimensional variation can be increased in proportion to the number of piezoelectric layers.

[0027] The described device may also include a device for providing an operating voltage to the piezoelectric element, the device being electrically connected to the piezoelectric element. The device can generate a specifically adjustable voltage, which is then present at the at least one piezoelectric element. Variations in the amplitude of the operating voltage, which is a DC voltage, can then induce dimensional changes.

[0028] The device may include at least one force transmission element for transmitting a piezoelectric force generated by the piezoelectric element and / or converting the piezoelectric force generated by the piezoelectric element into a braking force to brake the relative movement.

[0029] In the proposed method, a target braking force is determined, wherein a voltage assigned to the target braking force is applied to a piezoelectric element. In this case, the voltage can be provided by a voltage source. The voltage source can in turn be controlled by a control device, wherein the control device can control the voltage source to provide the target voltage, in particular by transmitting a corresponding control signal. Specifically, the braking force can thus be set continuously or with a predetermined resolution within a predetermined range from a minimum settable braking force to a maximum settable braking force, wherein different voltage levels can be assigned to different braking forces, which are predefined as target voltages for setting the target braking force. If the minimum settable braking force is set, the relative movement can be released (released state). If the maximum settable braking force is set, the relative movement can be braked to its maximum (maximum braking state). If a braking force between these limit values is set, a partial braking state can be set.

[0030] The control device can be configured as a computing device, which in turn can be configured as or include a microcontroller or integrated circuit. The control device can be part of the coordinate measuring machine. However, the control device can also be provided by an external device (e.g., an evaluation computer in the form of a PC) that is connected to the coordinate measuring machine for data and / or signaling. Similarly, the voltage source can be part of the coordinate measuring machine.

[0031] This method advantageously enables simple and reliable setting of the braking force. Overall, the use of a piezoelectric element advantageously ensures rapid and reliable generation of the braking force, wherein the braking force can advantageously be set continuously (i.e., with a desired resolution) to a value from a predetermined range of values. Furthermore, the use of a piezoelectric element reduces power losses during brake operation, particularly when the piezoelectric element is at rest. In this respect, the power loss of a piezoelectric element can be compared to that of a capacitor, where the power loss is proportional to the rate of change of the applied voltage and a low, constant current flowing through a non-infinite internal resistance. When slow changes occur and when there are long periods of invariance, as is typically the case during measurement operations on a coordinate measuring machine, the power loss is advantageously very low. Furthermore, the thermal load on the device's surroundings is reduced, which is particularly advantageous for use in coordinate measuring machines, as thermally induced deformation of components can lead to measurement inaccuracies.

[0032] The use of piezoelectric elements results in a relatively high force-to-mass ratio for the braking system. Furthermore, the braking system can be manufactured in a compact form, requiring minimal installation space and having a small number of components. The system can be configured so that the braking state is established in the event of a failure of the operating voltage of the piezoelectric element, which advantageously increases operational safety.

[0033] In another embodiment, the voltage is varied to continuously change the braking force. Specifically, the actual braking force can be continuously adjusted to the target braking force. Furthermore, the braking force in a partial braking state (e.g., after setting the target braking force) can advantageously be varied continuously, particularly in a manner dependent on the application and / or environmental conditions. Exemplary application-related settings of the braking force are explained in even greater detail below.

[0034] In another embodiment, during a position control mode for setting the relative position of the movable part, a voltage is applied to the piezoelectric element such that the braking force is less than the maximum settable braking force and greater than the minimum settable braking force. Thus, a partial braking state can be set in position control mode. In position control mode, the position (particularly the position of the shaft element) is set based on the control difference. This advantageously reduces overshoot in position control mode and / or compensates for tangential errors in the arc-second range during brake application. Tangential errors can represent angular errors in the rotor's direction of rotation. These errors can typically be detected by an angle measurement system.

[0035] Specifically, during the position control mode, both the braking force and the driving force / torque generated by the drive device can be varied (particularly, at least sometimes simultaneously), wherein the braking force can be set to a value that is less than a maximum settable braking force and greater than a minimum settable braking force. Furthermore, a method for setting a relative position between two parts of a coordinate measuring machine that are movable relative to one another is described, wherein both the braking force and the driving force / torque generated by the drive device can be varied (particularly, at least sometimes simultaneously), wherein the braking force can be set to a value that is less than a maximum settable braking force and greater than a minimum settable braking force. Specifically, the described method can be developed according to one of the following aspects.

[0036] Specifically, the change in braking force can be dependent on the change in driving force / torque. For example, if the driving force decreases, the braking force can be increased, particularly if a target relative position is set or if the deviation between the actual relative position and the target relative position is less than a predetermined amount. For example, the braking force and driving force / torque can be set in the context of multiple output position control.

[0037] Furthermore, the braking force can advantageously be set such that relative position changes caused in particular by purely weight forces are prevented, but relative position changes caused by driving forces are possible. Weight-induced relative position changes are explained in even greater detail below. A driving-force-induced relative position change refers to a relative position change caused by the driving force / driving torque. An inertia-dependent and / or position-differential-dependent setting of the braking force is also possible, as will also be explained in greater detail below.

[0038] If, for example, an actual relative position is set due to position control, and upon reaching this actual relative position, a braking state is set, and the drive force / drive torque is subsequently reduced (in particular, to zero), a change in the actual relative position may occur, for example due to the mechanical properties of the system comprising the drive device and the movable part, for example, by using elastic elements or due to play between the components. This change can then be reduced or completely compensated for by setting the braking force such that a change in the relative position due to the drive force is possible even in a partially braked state, but a change in the relative position due, in particular, to pure weight forces is prevented.

[0039] Similarly, the proposed setting of the braking force to a value less than the maximum settable braking force and greater than the minimum settable braking force makes it possible to reduce weight-induced variations in the driving force. For example, if the load is moved by relative motion, a high driving force / torque may be particularly required when decelerating a large load. This can result in undesirably high currents and require a high control dynamic range for the drive control. If the braking force is then set separately as explained, the driving force / torque required for deceleration can be reduced, particularly since the braking force forms part of the force required for deceleration. Thus, drive control with a smaller dynamic range can also be achieved.

[0040] Likewise, the proposed setting of the braking force to a value less than the maximum settable braking force and greater than the minimum settable braking force enables the control of the drive device during relative movement in which the load counter moves in opposition to the weight force acting on the load counter to be performed in a manner similar to the control of the drive device during relative movement in which the load moves together with the weight force acting on the load. As a result, the complexity of the control of the drive device can be reduced.

[0041] Of course, it is conceivable that, outside of the position control mode, a voltage is also applied to the piezoelectric element such that the braking force is less than the maximum adjustable braking force and greater than the minimum adjustable braking force. As a result, a desired and, in particular, application- and / or environmental-condition-dependent self-deceleration of the relative movement can be set.

[0042] In another embodiment, the target braking force is determined so as to fully or at least partially compensate for the driving force caused by the weight force on the load for relative movement, the position and / or orientation of the load being determined by the relative movement. Specifically, this target braking force may be between the limit values explained above. Specifically, this target braking force may be set if the goal is to maintain a constant relative position (stationary) between the movable parts. In this regard, compensation may be achieved such that the brake is closed to a degree specifically related to the load force or weight force, or the braking force may be set such that the load is not moved, at least due to the weight force acting on the load.

[0043] Specifically, the load can be a sensor of a coordinate measuring machine, optionally with a sensor carrier fixed thereto. The load can be mechanically connected to one of the parts that are movable relative to each other, directly or indirectly (e.g. via another movable part). The weight force acting on the load can then be the driving force for the weight-induced relative movement. This driving force can, for example, exert a weight-induced torque on a rotating axis element or a weight-induced driving force on a linear axis element. Specifically, the proposed determination of the target braking force makes it possible to simplify position control when stationary, since the weight-induced driving force does not have to be compensated by the drive device. This results in energy-saving operation of the coordinate measuring machine and high position fidelity (especially when stationary), which enables high measurement accuracy (especially during measurements with optical sensors).

[0044] In this case, particularly when position control is implemented, it is possible to determine the weight force or weight-induced driving force for the relative movement. For example, the position and / or orientation (pose) of the load in a reference coordinate system can be determined, wherein the current weight-induced driving force for the relative movement can then be determined based on the pose, particularly based on a kinematic model of a mechanical system (i.e., particularly a coordinate measuring machine) that includes at least the load and parts that are movable relative to one another. The pose can be detected by sensors using a detection device or determined based on the relative position of movable parts of the coordinate measuring machine, for example, the relative position being detected by sensors or determined computationally.

[0045] Alternatively or cumulatively, the target braking force is set based on at least the inertia of the load. The inertia can be previously known or can be determined using a corresponding determination method. Specifically, the inertia can be assigned one or more target braking forces, specifically one or more target braking forces depending on the operating state, wherein the target braking force to be set is then determined and set based on this assignment. The assignment can be provided in the form of a lookup table, a characteristic map, a functional relationship, or a model, in particular a machine learning model.

[0046] If a drive device achieves a particularly high acceleration of one of the parts that are movable relative to one another, which drives the drive torque / force on the movable part and thus also accelerates the load (first scenario), a corresponding force acts on at least one of the parts that are movable relative to one another due to the inertia of the load. This has the effect that the target relative position of the two movable parts may deviate from the actual relative position by more than a predetermined amount and / or for a predetermined duration. The higher the inertia, the greater this deviation may become. In the position control mode of the drive machine, this can then lead to control interventions with high drive torques. However, this also increases the energy consumption and possibly the thermal load of the drive system. This can be avoided or at least reduced by implementing an inertia-dependent setting of the target braking force, in particular by setting the target braking force to be higher or lower overall for a higher inertia.

[0047] If the entire drive system, including the drive unit, the parts movable relative to one another, and the braking device, is moved by a separate, particularly external, positioning device (e.g., a robot or gantry system) (second scenario), the associated acceleration of the load can also exert a force on at least one of the movable parts due to inertia. This can also have the effect of causing the target relative position of the two movable parts to deviate from the actual relative position by more than a predetermined amount and / or for a predetermined duration. If, after such positioning is performed by the separate positioning device, the drive machine is then operated in position-controlled mode with the intention of maintaining the position set before positioning began, the deviations, as explained above, can in some cases lead to control interventions with high drive torques. The disadvantages explained above can be avoided or at least reduced by setting the target braking force in relation to inertia, particularly by setting the target braking force higher with higher inertia. Furthermore, the braking force can be set in relation to the magnitude of the acceleration, for example by setting the braking force higher with greater acceleration.

[0048] However, in both cases explained, operation can preferably occur without the brake being fully closed, i.e., only partially braking. This advantageously allows the position to be continuously changed, particularly by operating the drive, for example to correct for residual deviations. Because the torque dictated by inertia can be fully or at least partially compensated by the braking force, the drive current for the drive can advantageously be zero or assume a low value, particularly when implementing position control for the drive to maintain a set position. Furthermore, a controller that is easy to implement and operate, e.g., with a small proportional component and therefore high robustness, can be used for this purpose. This effect can be further enhanced if a predetermined deviation from this set position is tolerated during the position control of the drive.

[0049] Alternatively or cumulatively, the target braking force can be set based on the difference between the target relative position and the actual relative position of the movable parts. Specifically, the braking force can be reduced as the position difference increases, particularly in the event of a desired positive acceleration of the load. Symbolically, this can correspond to a hill start scenario for a motor vehicle. As a result, a smaller deviation from the target trajectory with the lowest possible power consumption and thermal load can be advantageously achieved.

[0050] Furthermore, the braking force can be increased as the position difference decreases, particularly in the event of a desired negative acceleration of the load. This can symbolically correspond to the scenario of braking a motor vehicle on a hill. This advantageously achieves high positioning accuracy and shortens the usual sequential sequence of positioning, braking, and shutting down the drive.

[0051] In summary, the described embodiments advantageously allow the operation of the drive system, particularly in position-controlled mode, to be influenced by simultaneously operating two actuators: the braking device and the drive unit. In this case, the actuators can be operated dynamically and, in particular, the manipulated variables they generate can be varied simultaneously. In other words, an MO (Multiple Output) control system is thus provided, in which the output variables are the braking torque and the drive torque generated by the drive unit. As a result, it is also possible to avoid undesirable changes in the load position that could occur after setting the maximum braking force due to the elastic properties of the elements in the drive train between the drive unit and the load, by not increasing the braking force abruptly but, preferably, continuously up to the maximum braking force.

[0052] In another embodiment, the weight of the load is determined, wherein the weight-induced driving force for the relative movement is determined based on the weight.The weight of the load can, for example, be determined at least partially by the explained control device.

[0053] As an example, the identity of the load can be determined. A weight can then be assigned to this identity. The corresponding assignment can be stored, for example, in a readable storage device.

[0054] As the weight of the load, the weight of the identity assigned to the load (i.e., the load-specific weight) can then be determined.

[0055] This identity can be determined, for example, by detecting identity information of the load that encodes or indicates the identity, particularly in a contactless or contactless manner. For example, the identity information can be detected optically, radio-based, or in some other contactless manner. For this purpose, the coordinate measuring machine can include a correspondingly configured detection device. The load can thus provide identity information in a detectable or readable form, for example, in the form of an optically detectable feature (e.g., a QR code) or a radio-readable element (e.g., an RFID tag). This advantageously simplifies the determination of the specific weight of the load.

[0056] In another embodiment, the weight of the sensor is determined as the weight of the load during or after removal of the sensor from a sensor cartridge of the coordinate measuring machine. The coordinate measuring machine may have, for example, a replacement interface for receiving or securing different sensors, each having a sensor-specific weight. The coordinate measuring machine may also include a sensor cartridge in which at least two different sensors are stored or can be stored. These sensors can be stored, for example, at different storage locations in the sensor cartridge.

[0057] During or after receiving a sensor at the replacement interface, in particular during or after sensor replacement, the weight of the sensor can be determined as a load-specific weight, for example, in one of the above-described methods. Furthermore, it is conceivable to assign a sensor-specific weight to a storage point that corresponds to the weight of the sensor stored there. Furthermore, a storage point can be assigned a predetermined receiving position, into which the replacement interface must be positioned in order to receive the sensor.

[0058] If the replacement interface of the coordinate measuring machine is positioned in a receiving position, in particular for receiving a sensor stored at a storage point assigned to this receiving position, the weight assigned to this receiving position can be determined as the weight of the load. This advantageously simplifies the determination of the load-specific weight.

[0059] However, as an alternative to determining the weight of the load, the weight-induced driving force for the relative movement can also be determined in some other form, for example detected by a sensor and / or calculated.

[0060] Furthermore, a coordinate measuring machine is proposed, which has at least two parts that are movable relative to one another, at least one device for braking the relative movement, comprising at least one piezoelectric element for generating a braking force, at least one control device, and at least one device for supplying a voltage to the piezoelectric element, wherein

[0061] The control device determines a target braking force and controls the voltage supply device so that the voltage assigned to the target braking force is applied to the piezoelectric element. Thus, the coordinate measuring machine is configured so that the method according to one of the embodiments described in this disclosure can be performed using the coordinate measuring machine. The corresponding advantages have been explained above.

[0062] Furthermore, a device for braking relative movement between two parts of a coordinate measuring machine that are movable relative to one another is described, wherein the device includes at least one piezoelectric element for generating a braking force, wherein the device is configured to generate a braking force for braking the relative movement. The device can be configured according to one of the embodiments of the braking device described in this disclosure.

[0063] Furthermore, a device for braking a rotating axis element, in particular for braking a relative movement between two parts of a coordinate measuring machine that are movable relative to one another, is proposed. The aspects explained in connection with this device can also be implemented in the context of the device explained above for braking a relative movement (i.e., independently of the rotating axis element).

[0064] The device can also be used to lock a rotating shaft element. Specifically, the rotating shaft element can be configured as a shaft. The shaft can be configured as a solid body or alternatively as a hollow body. The rotating shaft element can be mechanically coupled to a drive device, for example, via at least one gear mechanism and / or at least one coupler. Thus, the drive device and the rotating shaft element can be coupled so that operation of the drive device causes the rotating shaft element to rotate about an axis of rotation. Specifically, the axis of rotation can be the central longitudinal axis of the rotating shaft element. Furthermore, the rotating shaft element can be mounted in / on at least one mounting device.

[0065] The proposed device may further comprise at least one drive device, at least one coupling, at least one gear mechanism and / or at least one mounting device.

[0066] The device includes at least one piezoelectric element.

[0067] Furthermore, the device includes at least one first force transmission element for transmitting the piezoelectric force generated by the piezoelectric element to the rotating shaft element. In this regard, the piezoelectric force generated by the piezoelectric element can be introduced into the first force transmission element and transmitted by the first force transmission element to the rotating shaft element. Thus, in this sense, the transmitted piezoelectric force / transmitted piezoelectric torque can act on the rotating shaft element for braking purposes. Of course, it is also conceivable that the piezoelectric force for braking purposes can be transmitted to the rotating shaft element via multiple force transmission elements, which can be mechanically connected in series or in parallel.

[0068] The force transmission element, in particular the first force transmission element, can also convert the force into a braking torque for the rotating shaft element.

[0069] According to a first alternative embodiment of the present invention, the force transmission element is configured as or includes a brake disc that can be fixed (e.g., screwed) to the rotating shaft element, at least for joint rotation. Specifically, the brake disc can have a through-opening. The rotating shaft element can extend through the through-opening or into the through-opening. Preferably, the brake disc is fixed to a fixing section on the rotating shaft element, in particular, at the free end of the rotating shaft element. The maximum radius of the brake disc can be greater than the maximum radius of the rotating shaft element. Specifically, the fixing section can be arranged in a central section of the brake disc.

[0070] The brake disc may preferably be rigidly fixed to the rotating shaft element, ie for joint rotation and translation.The brake disc may have a radius in the range of 30 mm to 50 mm, in particular a radius of 38 mm.

[0071] Furthermore, the brake disc reduces the axial and / or radial portion of the piezoelectric force transmitted by the brake disc to the rotating shaft element. In other words, the brake disc is arranged and / or configured so as to reduce the axial and / or radial portion of the piezoelectric force transmitted by the brake disc to the rotating shaft element. The axial portion here refers to the portion oriented parallel to the explained rotation axis of the rotating shaft element. In this respect, in particular, the axial portion of the force exerted by the brake disc on the rotating shaft element can be smaller than the axial portion of the force introduced into the brake disc. The radial portion here refers to the portion oriented parallel to the radial direction relative to the rotation axis. In this respect, in particular, the radial portion of the force exerted by the brake disc on the rotating shaft element can be smaller than the radial portion of the force introduced into the brake disc.

[0072] Preferably, the brake disc is configured to be rigid in the tangential direction, but flexible in the axial and / or radial directions. Specifically, the stiffness in the axial direction (i.e., parallel to the rotational symmetry axis of the brake disc) can be lower than the stiffness in the tangential direction at a point on a circular line around the rotational symmetry axis. Alternatively or cumulatively, the stiffness in the radial direction can be lower than the stiffness in the tangential direction at a point on a circular line around the rotational symmetry axis.

[0073] Specifically, the brake disc can be formed from a material with an elastic modulus equal to that of spring steel, or with an elastic modulus that deviates from that of spring steel by no more than a predetermined percentage (e.g., no more than 5% or 10%). For example, this material can be metal, particularly spring steel. The brake disc can have a thickness of less than 1 mm, particularly less than or equal to 0.3 mm. The brake disc material can be a flexible and / or non-brittle material, such as high-grade steel X38Cr13Mo1. This material can be hardened and / or annealed to exhibit low stress. The brake disc can preferably be formed to have properties such that for a point / segment on the circumference of the brake disc that is displaced 1 µm in the axial direction, the force acting on this point / segment in the axial direction is less than or equal to 0.0267 N.

[0074] The surface of the brake disc may be polished and may have a roughness less than or equal to 2 μm RA, preferably less than or equal to 0.4 μm RA.

[0075] The described properties of the brake disks make it possible to reliably brake the rotational movement of the rotary shaft element individually, in combination or as a whole, while simultaneously preventing or minimizing bending of the rotary shaft element about a bending axis oriented perpendicular to the axis of rotation.

[0076] It is conceivable that the optionally transmitted piezoelectric force is applied to the brake disc in a first actuation section, in particular, in an actuation section in a radially outer section of the brake disc. This actuation section may extend along a circular centerline having a radius greater than the radius of the rotational axis element but less than the maximum radius of the brake disc. In this case, the aforementioned axis of rotational symmetry may be oriented perpendicular to the described actuation section of the brake disc.

[0077] Specifically, the piezoelectric force can be transmitted via at least one braking element (e.g., a brake shoe or brake pad) to the actuation sections on the front and / or rear surfaces of the brake disc. For example, a first braking element can be provided for actuating the front side, and a second braking element can be provided for actuating the rear side. In this case, the actuation sections can be arranged at the same or different radial distances on the front and / or rear sides. In other words, the radius of the circular centerline along which the actuation sections extend on the front and rear sides can be the same or different.

[0078] As a result, it is advantageously provided that during the transmission of the piezoelectric force for braking the rotary shaft element, no force or only a reduced force is transmitted to the rotary shaft element along the rotary axis, thereby ensuring in particular a high position accuracy with regard to the position along this axis.

[0079] According to a second alternative embodiment of the present invention, the force transmission element is configured as or includes a cylindrical element. The cylindrical element can be arranged in the rotation axis element, which is a hollow element in this embodiment. Furthermore, the cylindrical element is mounted in the rotation axis element so as to be movable in the axial direction.

[0080] In a third alternative according to the present invention, the first force transmission element is configured as or includes a hollow cylindrical element having an inner volume for receiving the rotation axis element and being movably mounted on the rotation axis element in the axial direction.

[0081] As a result, it is advantageously provided that the force transmission element does not exert an axial force on the axis, as already explained above, which ensures a high position accuracy of the rotary axis element.

[0082] The cylindrical element according to the second alternative and the third alternative is deformable, in particular elastically deformable, by applying a force. Specifically, when a force is applied to the cylindrical element, the maximum radius or the maximum diameter of the cylindrical element can increase or decrease.

[0083] Due to the force exerted on the cylindrical element and / or due to its properties (particularly its elastic properties), the cylindrical element may be deformed or capable of deformation and thus placed in a braking state, in which the cylindrical element applies a braking force / torque on the rotating shaft element. Specifically, the braking state can be defined as a released state. Similarly, the cylindrical element can be placed in a released state, in which it applies no braking force / torque on the rotating shaft element, or applies a comparatively reduced braking force / torque. In this case, the braking state refers to a state in which the cylindrical element brakes the rotating shaft element.

[0084] The cylindrical element according to the second and third alternatives can include or form an actuating section, wherein a piezoelectric force generated by the piezoelectric element or a piezoelectric force transmitted to the first force transmission element by at least one additional force transmission element can be applied to the actuating section. As an example, the cylindrical element can include at least one outwardly or inwardly protruding bridge, wherein the piezoelectric force can be applied to this bridge.

[0085] Specifically, the cylindrical element according to the second alternative can be arranged and / or configured so that when a piezoelectric force is applied, the cylindrical element expands, that is, the maximum diameter of the cylindrical element increases. As a result, the lateral outer surface of the cylindrical element can be pressed against the lateral inner surface of the rotating shaft element and exert a friction force on the rotating shaft element, which is used to brake the rotating shaft element. Therefore, a braking state can be set accordingly. Correspondingly, the release state can be set by applying a piezoelectric force for contraction to the cylindrical element. In the second alternative, specifically, the braking state can be the expanded state of the cylindrical element, and the release state can be the contracted state.

[0086] The hollow cylindrical element according to the third alternative can be arranged and / or configured so that when a piezoelectric force is applied, the hollow cylindrical element contracts, that is, the cylindrical element reduces its maximum inner diameter. As a result, the lateral inner surface of the hollow cylindrical element can be pressed against the lateral outer surface of the rotating shaft element and, as explained above, exert a friction force on the rotating shaft element. Therefore, a braking state can be set accordingly. Correspondingly, the release state can be set by applying a piezoelectric force for expansion to the cylindrical element. In the third alternative, the braking state can, for example, be a contracted state of the hollow cylindrical element, and the release state can be an expanded state.

[0087] The cylindrical element can be configured so that the lateral outer surface or the lateral inner surface is pressed along a predetermined proportion of the circumferential length of the lateral inner surface or the lateral outer surface of the rotating shaft element, wherein the proportion is greater than 50%, preferably greater than 75%, and more preferably greater than 90%. In other words, the cylindrical element does not necessarily need to be configured as a completely cylindrical shape, but can also be configured as a partially cylindrical shape.

[0088] The device may comprise at least one return spring element in order to switch the cylindrical element from the braking state to the released state or vice versa, or to support this switch.

[0089] Specifically, the fact that the cylindrical element according to the second and third alternatives is movably mounted on the rotation axis element in the axial direction can mean that the cylindrical element in the released state can be moved in the axial direction, wherein no friction force or only a low friction force (in particular, a friction force less than a predetermined threshold value) is exerted on the rotation axis element. Specifically, the cylindrical element can be mounted in / on the rotation axis element and / or in / on the mounting device by spring mounting and / or sliding mounting, wherein the rotation axis element is rotatable relative to the mounting device.

[0090] In another embodiment, the piezoelectric element is an amplifying piezoelectric actuator. This amplifying piezoelectric actuator typically comprises at least one piezoelectric element (preferably a stacked actuator as explained above) and a frame element, wherein the at least one piezoelectric element is arranged within the frame element. Specifically, the frame element can be formed from metal (e.g., steel). Preferably, the frame element has a (partially) elliptical or (partially) polygonal cross-section, particularly a (partially) hexagonal cross-section. In this case, the at least one piezoelectric element is arranged within the frame and connected to the frame so that the piezoelectric force generated by the piezoelectric element is amplified by the frame. Purely by way of example, the at least one piezoelectric element can be arranged within the frame so that its deformation direction (i.e., the direction of its dimensional change when the voltage changes) is oriented parallel to the longitudinal axis of the frame element. The frame element can then be connected to the piezoelectric element at its two free longitudinal ends. When the piezoelectric element changes in size, the frame element also changes in size along its longitudinal axis, which causes a dimensional change along the frame element's transverse axis. The interface section of the frame element for transmitting force to another element can then be arranged or formed on the lateral sides of the frame element, particularly between the longitudinal ends. This design allows for a predetermined force and / or stroke transmission. Specifically, the piezoelectric force can be introduced into the frame element via the section connected to the piezoelectric element and further supplied / transmitted via sections different from those sections (particularly sections on the lateral sides). For example, the first force transmission element described above can then be actuated via the interface section. However, a further (third) force transmission element can also be actuated, which would then transmit the piezoelectric force to the first force transmission element.

[0091] Thus, the frame element can form an additional force-transmitting element. The piezoelectric element and, optionally, the frame element 8 can be arranged in a common housing. Furthermore, a converter (particularly a so-called step-up converter) can also preferably be arranged in the housing, which converts an input voltage, for example, provided by a voltage source, into an output voltage with a higher amplitude. This advantageously eliminates the need to install long, high-voltage power leads; in particular, these can be arranged in a protected manner in the housing.

[0092] The output voltage can then be the operating voltage of the piezoelectric element. Furthermore, a control device for setting the operating voltage can be arranged in the housing, wherein the control device controls the converter and / or the voltage source, for example, to set the actual operating voltage according to a target voltage. The target voltage can be determined based on a target braking force, for example, by a host computer system.

[0093] The use of an amplified piezoelectric actuator advantageously results in a particularly high force-to-mass ratio for the device relative to the brake force that can be generated. Furthermore, the frame element mechanically protects the at least one piezoelectric element, particularly against contamination and tension. Similarly, the at least one piezoelectric element can be prestressed by the frame element, thereby particularly supporting the reversal of dimensional changes. This advantageously achieves a longer service life and improved braking behavior.

[0094] In another embodiment, the piezoelectric element is coupled to the first force transmission element via at least one further force transmission element. The piezoelectric element can be coupled to the first force transmission element via precisely one further force transmission element. However, preferably, the piezoelectric element is coupled to the first force transmission element via a plurality of further force transmission elements. Via these force transmission elements, a piezoelectric force can be transmitted from the piezoelectric element to the first force transmission element. An exemplary further force transmission element is the frame element explained above. Alternatively, such a further force transmission element can be configured as a lever mechanism or provide a lever mechanism.

[0095] Specifically, the additional force-transmitting element can be used to transform the force applied to the additional force-transmitting element. In this regard, the additional force-transmitting element can be configured to extend or shorten the stroke caused by the dimensional change of the piezoelectric element. Alternatively or cumulatively, the additional force-transmitting element can be configured to amplify or attenuate the generated piezoelectric force.

[0096] As a result, it is advantageously provided that the stroke and / or the actuating force for actuating the first force transmission element can be adapted, thereby in turn making it possible to reliably brake the rotary shaft element.

[0097] In another embodiment, at least one additional force-transmitting element is configured as a pliers element. Specifically, such a pliers element may include at least one, preferably two, lever arm sections, via which force is introduced into the pliers element. Furthermore, the pliers element may include at least one, preferably two, load arm sections, which may form a pliers head and, via which force transmitted by the pliers element may be directed out of another force-transmitting element or applied to another element. Such a pliers element may function according to the principle of leverage. Specifically, the pliers element may be configured such that force introduced via the lever arm section may be converted in a manner that shortens the stroke and output via the load arm section. In this process, force may be increased. The pliers element may include two lever elements, specifically, the two lever elements rotatably connected to each other via a joint section. In this case, the lever element may have a lever arm section and a load arm section, or may form a lever arm section and a load arm section. Specifically, such a pliers element may be referred to as a bilateral pliers element because it may have two movable lever arm sections. In particular, the first force transmission element can be clamped between the force arm sections in order to introduce force into the first force transmission element.

[0098] However, it is also conceivable that the pliers element is configured as a single-sided pliers element, which includes, for example, a lever element that has a load arm section and a lever arm section or forms a load arm section and a lever arm section and is rotatably mounted. Such a single-sided pliers element can have / form only one lever arm section. Specifically, the first force transmission element can be clamped between the lever arm section and the stop element in order to introduce force into the first force transmission element.

[0099] The use of a forceps element as an additional force transmission element advantageously results in a particularly good transformation of the piezoelectric force and / or the stroke caused by the dimensional change for actuating the first force transmission element. Thus, in combination with the additional force transmission element, a reliable actuation of the first force transmission element is advantageously possible for the purpose of reliably braking the rotating shaft element.

[0100] In another embodiment, the forceps element is configured as a single-sided forceps element. This and the corresponding advantages have been explained above. In addition, it is advantageously provided that the number of movable parts of the device is reduced, thereby making it possible to reduce manufacturing complexity, manufacturing costs, and maintenance complexity.

[0101] Specifically, in another embodiment of the second alternative and the third alternative, the (hollow) cylindrical element is slotted. In this case, the slots may extend along the lateral surfaces and / or along the longitudinal extent (i.e., parallel to the central axis) of the cylindrical element. The slots may extend along the entire length of the cylindrical element, or along only a portion of the total length, where the total length is the length along the central axis.

[0102] At least one piezoelectric element can be at least partially arranged in the groove, that is, between the free end sections of the cylindrical element (particularly the lateral sections of the cylindrical element) that define the groove. As explained above, the cylindrical element can have or form at least one, preferably two, bridges that protrude outward or inward from the lateral outer or inner surface. Such bridges can preferably be arranged or formed in the region of the end of the cylindrical element that defines the groove. In other words, the radial length of the groove can be extended by the bridges. The at least one piezoelectric element can then be at least partially, or even completely, arranged in the extended groove or in the groove formed between these bridges.

[0103] This advantageously enables a reliable transmission of force from the piezoelectric element to the cylindrical element in order (as explained above) to expand or contract the cylindrical element and thus set the braking or release state. Likewise, the installation space of such a device is advantageously minimized.

[0104] In another embodiment, in particular according to the second alternative or the third alternative, the cylindrical element has a tapered section. In this embodiment, in particular, the cylindrical element can be configured as a hollow cylindrical element. The tapered section can then be a partial section of a lateral section of the hollow cylindrical element. Likewise, this section can extend along the lateral surface and / or along the central axis. In the tapered section, the width of the lateral section in the radial direction can be reduced compared to the section of the lateral section that is arranged adjacent to the tapered section. This advantageously makes it possible to form a rotary joint, thereby simplifying the dimensional changes of the cylindrical element, i.e. in particular the expansion and contraction. As a result, it is advantageously provided that a portion of the piezoelectric forces that cause the deformation of the cylindrical element can be reduced, thereby in turn providing a higher braking force. Likewise, a simpler and more reliable setting of the braking and release states is advantageously provided.

[0105] In another embodiment, the cylindrical element comprises or forms a hollow cylindrical element, more specifically, according to the second and third alternatives, a spring joint segment. The movable mounting in the axial direction in / on the rotation axis element can be achieved via this spring joint segment. The spring joint segment can be arranged or formed on the lateral outer surface / lateral inner surface of the cylindrical element. Specifically, the lateral segment of the cylindrical element and the spring joint segment can be formed integrally. In this case, the spring joint segment is arranged and / or formed so as to generate a spring force acting in a radial direction or opposite to the radial direction between the cylindrical element and the rotation axis element or a support element that is rotatable relative to the support element. For example, the support element can be part of or formed by the mounting device.

[0106] If the cylindrical element is arranged in the rotating axis element, this spring force can force the cylindrical element to move away from the lateral inner surface of the rotating axis element, especially if the distance between the cylindrical element and the rotating axis element in the radial direction and in the area of the spring joint section is less than a predetermined distance. In the case of the cylindrical element being deployed, this spring force needs to be overcome. However, in the retracted state, the spring force ensures that the cylindrical element is arranged as centrally as possible in the rotating axis element, and the contact area between the cylindrical element and the lateral inner surface of the rotating axis element is extremely small. As a result, firstly, it can be achieved that friction is minimized in the released state. Secondly, it can be achieved that only very small friction acts in opposition to the movement of the cylindrical element in the axial direction, thereby making it possible to achieve the movable installation explained above in a simple and reliable manner.

[0107] If the spring joint section is arranged between the cylindrical element and the support element, the spring force can force the cylindrical element away from the support element, particularly if the radial distance between the cylindrical element and the support element in the region of the spring joint section is less than a predetermined distance. This spring force must be overcome when the cylindrical element is deployed. However, the support element can be arranged and / or formed such that the spring force in the retracted state ensures that the cylindrical element is positioned as centrally as possible within the rotation axis element, and that no contact area occurs between the cylindrical element and the lateral inner surface of the rotation axis element. The corresponding advantages have been explained above.

[0108] Preferably, the spring joint section is arranged and / or formed such that it is rigid in the tangential direction and thus enables a reliable transmission of frictional forces against rotational movements in the braking state.

[0109] Furthermore, a coordinate measuring machine is proposed, which has at least one device for braking according to one of the embodiments described in the present disclosure. As already explained above, the use of such a device in a coordinate measuring machine is particularly advantageous because, due to the low power losses, only low thermal loads on the components of the coordinate measuring machine occur, especially during continuous operation, which in turn reduces the risk of thermally induced deformations and the resulting measurement inaccuracies.

[0110] Furthermore, it is advantageously provided that, due to the comparatively high generable braking forces, a high stiffness can be achieved, in particular during tactile measurements or in the braking state, which is particularly advantageous during measurements with relatively heavy sensors, since a high position accuracy of these sensors can be ensured, in particular in the braking state or during braking.

[0111] Furthermore, a description is given of a method for braking a rotating shaft element with a device according to one of the embodiments described in this disclosure. In this case, a voltage is applied to at least one piezoelectric element.

[0112] In another embodiment, during the position control mode of the rotating shaft element, a voltage is applied to the piezoelectric element such that the braking force is less than the maximum generative braking force. Preferably, during the position control mode, a voltage is applied to the piezoelectric element such that the braking force is greater than the minimum generative braking force. In other words, the rotating shaft element can rotate without the brake being fully engaged (i.e., in a partially braked state).

[0113] Preferably, no sudden voltage change is applied to the piezoelectric element. In other words, a voltage is applied to the piezoelectric element such that a voltage change within a predetermined period of time is less than a predetermined threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] The present invention will be explained in more detail on the basis of exemplary embodiments. In the accompanying drawings:

[0115] Figure 1 shows a perspective view of a first alternative embodiment according to the present invention,

[0116] Figure 2 Shown Figure 1 A schematic cross section of the embodiment shown in

[0117] Figure 3 shows a schematic illustration of a first alternative of the device according to the invention according to a further embodiment,

[0118] Figure 4 shows a schematic illustration of a first alternative of the device according to the invention in a further embodiment,

[0119] Figure 5 shows a schematic illustration of a first alternative of the device according to the invention in a further embodiment,

[0120] Figure 6a shows a schematic cross-section of parts of a second alternative of the device according to the invention,

[0121] Figure 6b shows a schematic cross-section of a second alternative embodiment of the device according to the invention,

[0122] Figure 6c shows a schematic cross-section of parts of a second alternative of the device according to the invention in another embodiment,

[0123] Figure 7 shows a perspective view of a force transmission element of a second alternative embodiment of the device according to the invention,

[0124] Figure 8 shows a perspective illustration of a third alternative of the device according to the invention,

[0125] Figure 9 Shown Figure 8 A plan view of the embodiment shown in FIG.

[0126] Figure 10 Shown Figure 8 A longitudinal section of the embodiment shown in FIG.

[0127] Figure 11 shows a schematic block diagram of a coordinate measuring machine according to the present invention,

[0128] Figure 12 shows a schematic flow chart of the method according to the present invention,

[0129] Figure 13 shows a schematic longitudinal section of another embodiment according to the invention, and

[0130] Figure 14 A schematic illustration of the thermal energy generated by a piezoelectric element is shown. DETAILED DESCRIPTION

[0131] The same reference numerals in the following text indicate elements having the same or similar technical features.

[0132] Figure 1 A perspective view shows a first alternative embodiment of a device 1 for braking a rotating shaft element 2 according to the present invention. The rotating shaft element 2 is configured as a hollow cylinder or includes a hollow cylindrical section, wherein the hollow cylinder has an interior volume 3. The rotating shaft element 2 is rotatably mounted in a mounting device 4, which can also be referred to as a stator. The mounting device 4 includes a housing, wherein the free end of the rotating shaft element 2 (also referred to as a rotor) protrudes from the housing. The illustration shows the axis of rotation R, along which the rotating shaft element 2 protrudes from the housing. A brake disc 5 is secured to the free end of the rotating shaft element 2 protruding from the housing. Specifically, the brake disc can be screwed into a securing section on the free end. The through-opening in the brake disc 5 for creating the threaded connection can be arranged along a circular line having a radius smaller than the outer radius of the brake disc 5. The illustration shows that the brake disc 5 has a central through-opening and is secured to the rotating shaft element 2 such that the interior volume 3 is accessible through the central through-opening.

[0133] The brake disc 5 is part of the device 1 for braking according to the invention and forms a first force transmission element of the device 1. Furthermore, the device 1 comprises a piezoelectric element 6 (see Figure 2 ), specifically, the piezoelectric element can be configured as a stacked actuator. Furthermore, device 1 includes a second force transmission element 7, which is configured as a plier element and is explained in even greater detail below. Furthermore, device 1 includes a frame element 8 as a third force transmission element, in which piezoelectric element 6 is clamped. The piezoelectric force generated by piezoelectric element 6 is transmitted via frame element 8 to plier element 7, and from there to brake disc 5.

[0134] Figure 2 Shown Figure 1shows a schematic longitudinal section of the device 1. It is apparent that the caliper element 7 includes two brake shoes 9a, 9b for actuating different surface sections of the brake disc 5. These brake shoes 9a, 9b are the actuating elements of the caliper element 7. They are arranged on the lever arm sections 10a, 10b of the caliper element 7 and are used to apply a force to the brake disc 5. In this case, the first brake shoe 9a can actuate a first surface section 11a of the brake disc 5, particularly in a force introduction section extending along a circular line, wherein the radius of this circular line is less than the maximum radius of the brake disc 5 and preferably greater than half the maximum radius of the brake disc 5. The second brake shoe 10b is used to actuate another surface section 11b on another surface of the brake disc 5, which is opposite to the surface having the first surface section 11a in the axial direction of the rotation axis R (symbolized by the arrow). This further surface section 11b also extends along a circular line, with a radius greater than the radius of the circular line of the first actuating section 11a. However, this is not mandatory. In particular, it can also be provided that the radii of the circular lines of the actuation sections 11 a , 11 b are equal to one another.

[0135] Furthermore, the illustration shows the load arm sections 12a, 12b of the pliers element 7, which are mechanically connected to the frame element 8 via screws 13. The mechanical connection via the screws 13 is purely an example. Of course, other types of connections for producing a mechanical connection to the pliers element 7 are also conceivable.

[0136] The first lever arm 14a of the pliers element 7 comprises a load arm section 12a and a lever arm section 10a, while the second lever arm 14b of the pliers element 7 comprises a second load arm section 12b and a second lever arm section 10b.

[0137] Specifically, the lever arms 14a, 14b are rotatably connected to each other via a rotary joint section 15, which can be configured as a flexure. Figure 3 Explain in more detail Figure 2 The functionality of device 1 is shown in FIG.

[0138] Figure 2 The brake shoes 9a, 9b are shown to be replaceably fastened to the caliper element 7. For this purpose, the brake shoes 9a, 9b have a rod-shaped fastening section that can be inserted into recesses 17a, 17b in the caliper element 7. The illustration shows that the recess 17b for inserting the second brake shoe 9b is configured as a through-opening in the second lever section 10b.

[0139] Furthermore, the illustration shows that the first brake shoe 9a is arranged in a blind hole opening 17a of a fixing screw 18, which is arranged in a threaded section of the pliers element 7, in particular in the region of the first lever section 10a. By screwing the fixing screw 18 into or out of the threaded section, the maximum braking torque and / or the residual deceleration in the released state can be set.

[0140] Preferably, at least one material of the brake shoes 9a, 9b, in particular of the actuation sections for actuating the brake disc 5, or the material thereof, differs from the material of the brake disc 5. Furthermore, the surface structure of the brake shoes 9a, 9b differs from the surface structure of the brake disc.

[0141] It is further preferred that at least one material of the brake shoes 9 a , 9 b or at least one material of the actuating section of the first force transmission element is softer than the material of the brake disk 5 .

[0142] If the piezoelectric element 6 is configured as a non-amplified stack actuator and the brake disk 5 has a radius of 38 mm, a braking force of approximately 40 N can be generated in the illustrated embodiment, thereby generating a total clamping force of approximately 400 Nm between the brake shoes 9 a, 9 b. A coefficient of friction of 0.1 can be assumed.

[0143] Figure 3 A schematic cross section of a first alternative embodiment of the device 1 according to the invention is shown. This comprises a piezoelectric element 6, a frame element 8 and a clamp element 7 as well as a brake disc 5. The illustration also shows the axis of rotation R, whose arrow symbolizes the axial direction of the rotating shaft element 2 (not shown) (see e.g. Figure 2 ). The cross-section of frame 8 is configured to be elliptical or substantially elliptical. The longitudinal axis of frame 8 in the cross-section is oriented parallel to the deformation axis D of piezoelectric element 6. If different voltages are applied to piezoelectric element 6, the dimensions of piezoelectric element 6 change along deformation axis D. Figure 3The piezoelectric element 6 is shown as an elongated actuator extending along a deformation axis D, which can be implemented as a stacked actuator. A frame element 8 is connected to the piezoelectric element 6 at its front and rear ends along the deformation axis. The piezoelectric element is thus clamped in the frame element 8. Along the deformation axis D between these fixed sections, the frame element forms interface sections 16a, 16b, which are mechanically connected to the load arm sections 12a, 12b of the pliers element. If the size (length) of the piezoelectric element 6 changes along the deformation axis D, in particular due to a change in the applied voltage, then due to the configuration and fixing of the frame element 8, this causes a change in the distance between the interface sections 16a, 16b along a transverse axis oriented perpendicular to the longitudinal axis of the frame element 8. In this case, the longitudinal axis and the transverse axis span the cross-sectional plane. The pliers element 7 can be actuated by this change in distance. If, for example, the size of the piezoelectric element 6 is reduced along the deformation axis D, the distance between the interface sections 16a, 16b increases, and the arm sections 10a, 10b of the pliers element 7 move toward each other. If, for example, the size of the piezoelectric element 6 is increased along the deformation axis D, the distance between the interface sections 16a, 16b decreases, and the arm sections 10a, 10b of the pliers element 7 move toward each other. This is because the lever elements 14a, 14b of the pliers element (already referred to in Figure 2 The brake disc 5 is mounted rotatably against each other via a rotary joint section 15, which has also been explained. If the lever sections 10a, 10b are moved toward each other, a force can be exerted on the brake disc 5.

[0144] In this case, the brake disc 5 is configured so as to reduce the axial portion and, alternatively but preferably, the cumulative radial portion of the piezoelectric force transmitted by the brake disc 5 to the rotating shaft element 2. Specifically, the brake disc 5 can be configured so that the change in position of the brake disc 5 in the axial and / or radial directions in the region of the actuating surface sections 11a, 11b is different from, and in particular, greater than, the change in position in the axial and / or radial directions along the fixed section. To this end, the brake disc 5 can be formed from a material that is flexible along the normal to the surface of the brake disc 5. Furthermore, the brake disc 5 can be formed from a material that is not flexible, or less flexible, in the circumferential direction.

[0145] Specifically, the illustrated embodiment enables continuous setting of the braking force, making it possible to set not only two states (generating the maximum possible braking force, generating the minimum possible braking force) but also braking forces between these values. This continuously variable setting of the braking force can occur, for example, during the start or stop of a rotational movement of the rotating shaft element 2. Specifically, a target braking force can be determined based on the load torque acting on the rotating shaft element 2 and / or the actual angular position of the rotating shaft element 2, wherein a target voltage is then determined based on the target braking force and applied to the piezoelectric element 6.

[0146] If the moment acting on the rotating shaft element 2 is caused by, for example, the weight of a load, whose position and / or orientation can be adjusted by a movement at least partially caused by the rotation of the rotating shaft element 2, then the braking force (particularly during the target position adjustment process) can preferably be set so that the braking force completely or at least partially compensates for the moment caused by the weight. In other words, in particular in position control mode, self-deceleration also occurs for the purpose of weight force compensation. However, self-deceleration can also occur when the vehicle is stationary.

[0147] Figure 4 A schematic cross section of an embodiment of a device 1 according to the invention according to a first alternative is shown. The device 1 comprises a piezoelectric element 6 and a frame element 8. In this respect, reference is made to the Figure 3 The explanation of the embodiment shown in FIG. Figure 3 Compared to the embodiment shown in FIG, the pliers element 7 is configured as a single-sided pliers element and includes only one lever arm 14a having a load arm section 12a and a force arm section 10a. The lever arm 14a is rotatably mounted on a stator section 19 via a rotary joint section 15. The stator section can be arranged, for example, to be stationary relative to the mounting device 4 of the rotating axis element 2. A first interface section 16a of the frame element 8 is mechanically connected to the load arm section 12a of the lever arm 14a. A second interface section 16b is fixed to the stator section 19.

[0148] In this case, a section of the brake disc 5 is arranged between the free end of the lever section 10 a and the stator section 19. When the piezoelectric element 6 is operated, a braking state can be generated in which the lever section 10 a presses the brake disc 5 against the stator section 19. Specifically, this can be achieved by varying the voltage present at the piezoelectric element so that the piezoelectric element 6 contracts along the deformation direction D. If the voltage is varied so that the piezoelectric element expands along the deformation direction D, a released state can be set.

[0149] Figure 5A schematic cross-section of a device 1 according to the invention, according to a first alternative embodiment, is shown. Device 1 also includes a piezoelectric element 6 clamped in a frame element 8. Device 1 also includes a stator segment 19. This stator segment 19 includes or forms a retaining arm segment 20. Similarly, stator segment 19 includes a braking segment 21, against the surface of which the brake disc 5, in the braking state, presses. The brake disc 5 and the piezoelectric element 6, together with the frame element 8, are arranged between the free end of the retaining arm segment 20 and the braking segment 21 of the stator segment 19. In this case, the first interface segment 16a of the frame element 8 is fixed to the free end of the retaining arm segment 20. The brake shoe 9 is fixed to the second interface segment 16b of the frame element 8 and can actuate the surface of the brake disc 5 to apply a braking force thereto. If the voltage applied to the piezoelectric element 6 is changed so that the piezoelectric element 6 contracts in the deformation direction D, the brake shoe 9 presses against the brake disc 5 and clamps the disc between the braking section 21 and the brake shoe 9. As a result, a braking state is established. If the voltage is changed so that the piezoelectric element 6 expands in the deformation direction D, the brake shoe 9 moves away from the brake disc and loses contact therewith, establishing a released state.

[0150] Figure 6a Portions of an apparatus 1 according to the present invention are shown according to a second alternative. The illustration shows a rotating shaft element 2 configured as a hollow cylinder or having hollow cylindrical sections. At least one section of a hollow cylindrical element 22 is arranged within the interior volume 3 of the hollow cylindrical rotating shaft element 2. In this case, the central axis of the hollow cylindrical element 22 can be oriented parallel or approximately parallel to the central axis of the rotating shaft element 2 (i.e., parallel to the axis of rotation R). A released state is shown. In this released state, the maximum radius of the hollow cylindrical element 22 is smaller than the inner radius of the rotating shaft element 2, in particular, by a predetermined amount. The illustration shows that the hollow cylindrical element 22 is configured in a slotted manner, with a slot 23 extending along the central axis of the hollow cylindrical element 22. Furthermore, the illustration shows that the hollow cylindrical element 22 has or forms a tapered section 24, preferably arranged radially on the opposite side of the hollow cylindrical element 22 from the slot 23. The hollow cylindrical element 22 forms a first force transmission element of the device 1 .

[0151] Furthermore, the first hollow cylindrical element 22 is movably mounted in the rotating shaft element 2 along the axial direction, ie along the central axis of the rotating shaft element 2 .

[0152] If the free ends of the hollow cylindrical element 22 defining the groove 23 are forced apart from each other, this Figure 6aIndicated by arrow 25, the lateral outer surface of hollow cylindrical element 22 presses against the lateral inner surface of rotating axis element 2. Specifically, the maximum radius of hollow cylindrical element 22 is increased. In this case, the partial elements of hollow cylindrical element 22 connected via tapered section 24 pivot relative to each other. In the braking state, specifically, the entire lateral outer surface of hollow cylindrical element 22 can bear against the lateral inner surface of rotating axis element 2 and exert friction on said surface, resulting in a braking state. In the released state, the lateral outer surface of hollow cylindrical element 22 that bears against the lateral inner surface of rotating axis element 2 can be smaller in comparison, in particular, smaller by more than a predetermined amount, in particular by more than 90%. Preferably, in the released state, no section of the lateral outer surface of hollow cylindrical element 22 bears against the lateral inner surface of rotating axis element 2.

[0153] Figure 6b A schematic cross section of a device 1 according to the invention according to a second alternative is shown. The rotating shaft element 2 and the hollow cylindrical element 22 are shown, in which case reference can be made to the arrangement and configuration of these elements. Figure 6a The embodiment shown in Figure 6a , the hollow cylindrical element 22 has bridges 26 which are arranged at the free ends of the hollow cylindrical element 22, which bound the groove 23 and which extend into the interior volume enclosed by the hollow cylindrical element 22. The piezoelectric element 6 and the frame element 8 as a whole are arranged between these bridges 26 and therefore also in the groove 23, wherein the first interface section 16 a of the frame element 8 is mechanically connected to the first bridges 26 and the second interface section 16 b of the frame element 8 is mechanically connected to the second bridges 26.

[0154] The hollow cylindrical element 22 may partially protrude from the inner volume 3 of the rotation axis element 2 , wherein the piezoelectric element 6 together with the frame element 8 is arranged in the section protruding from the rotation axis element 2 .

[0155] If the voltage present at the piezoelectric element is changed so that the piezoelectric element 6 contracts in the deformation direction D, the free ends of the hollow cylindrical element 22 are forced apart from each other by the bridge 26, and as explained above, the braking state is set. If the voltage present at the piezoelectric element is changed so that the piezoelectric element 6 expands in the deformation direction D, the free ends are pulled together by the bridge 26, as a result of which the release state can be set.

[0156] Figure 6cA schematic illustration of parts of a device 1 according to the invention according to a second alternative in another embodiment is shown. The rotary axis element 2 is shown, with arrows 27 symbolizing the rotational movement and direction. Furthermore, the illustration also shows Figure 1 FIG. 4 is a diagram showing a part of a mounting device 4 in which the rotary axis element 2 is rotatably mounted.

[0157] Likewise, the illustration shows a hollow cylindrical element 22 with a groove 23, in which case reference may be made to the description concerning Figure 6a An explanation of the embodiments shown in FIG.

[0158] Furthermore, a spring joint section 28 is shown, wherein the hollow cylindrical element 22 includes or forms the spring joint section 28. Via the spring joint section 28, the hollow cylindrical element 22 is supported on the mounting device 4, in particular, on the lateral inner surface of the bearing bushing section of the mounting device 4. This spring joint section 28 enables movable mounting in / on the rotating axis element 2 along the axial direction of the rotating axis element 2. Specifically, the spring joint section 28 is arranged and / or formed on the lateral outer surface of the hollow cylindrical element 22 and is arranged and / or formed so that when the distance between the lateral outer surface and the mounting device in the radial direction is less than a predetermined threshold, a spring force is generated between the hollow cylindrical element 22 and the mounting device in the radial direction or in the opposite direction. This spring force then forces the hollow cylindrical element 22 away from the mounting device 4. Specifically, the spring joint section 28 is arranged in the section of the hollow cylindrical element 22 that protrudes from the rotating axis element 2.

[0159] Figure 7 A perspective view of a cross section of a hollow cylindrical element 22 of a device 1 configured according to a second alternative is shown. The illustration shows a conical section 24 of the hollow cylindrical element 22, which has been described with reference to Figure 6a The spring plate 29a, 29b (see FIG. 24 ) is shown and extends along the lateral surface of the hollow cylindrical element 22 and forms a rotation joint. This rotation joint 24 enables the hollow cylindrical element 22 to be expanded and contracted in a simplified manner. In addition, the illustration shows spring plates 29a, 29b (see FIG. 24 ) forming the spring joint section 28. Figure 6c In this case, the first spring plate 29a is fixed or formed on a first longitudinal edge of the tapered section 24. The second spring plate 29b is fixed on a second longitudinal edge of the tapered section. The spring plates 29a, 29b protrude from the lateral outer surface of the hollow cylindrical element 22, particularly in the region of the tapered section 24, in a direction oriented between the tangential direction and the radially outward direction.

[0160] Figure 8A perspective view of a device 1 according to the invention according to a third alternative is shown. The device 1 comprises a Figure 3 6 and the frame element 8 of the embodiment described in . Furthermore, the device 1 comprises a hollow cylindrical element 30, which surrounds a section of the rotating axis element 2. This means that a section of the rotating axis element 2 is arranged in at least a part of the inner volume of the hollow cylindrical element 30. In other words, the hollow cylindrical element 30 can enclose a section of the rotating axis element 2, in particular like a collar.

[0161] same, Figure 8 A mounting device 4 for a rotating axis element 2 is shown, wherein the rotating axis element 2 is rotatably mounted in this mounting device 4. The rotating axis element 2 protrudes from this mounting device, wherein a hollow cylindrical element 30 surrounds a portion of the protruding section of the rotating axis element 2. Specifically, a portion of the protruding section of the rotating axis element 2 extends into a portion of the interior volume of the hollow cylindrical element 30. As is apparent, the hollow cylindrical element 30 protrudes beyond the free end of the protruding section of the rotating axis element 2. The hollow cylindrical element 30 is configured so that it is grooved along its lateral surface. The illustration also shows bridges 26, which are arranged in the section protruding beyond the free end of the rotating axis element 2 and extend from the lateral inner surface of the hollow cylindrical element 30 into the interior volume. The piezoelectric element 6 and the frame element 8 are arranged between these bridges 26. In this case, a portion of the piezoelectric element 6 and a portion of the frame element 8 can extend into the interior volume of the rotating axis element 2.

[0162] In this case, the hollow cylindrical element 30 is mounted on the rotating shaft element 2 so as to be movably mounted along the axial direction thereof.

[0163] Figure 9 Shown Figure 8 A schematic cross section of an embodiment is shown in FIG. Figure 9 The released state of the device 1 is shown in FIG. 1 . It can also be seen that the frame element 8 is connected via the interface sections 16a, 16b to the bridge 26 arranged in the region of the free end of the hollow cylindrical element 30. If the voltage present at the piezoelectric element is then changed so that the piezoelectric element 6 expands along the deformation direction, which is in the Figure 9 If the hollow cylindrical element 30 is oriented perpendicularly to the drawing plane and parallel to the axis of rotation R of the rotary shaft element 2, the bridge 26 is pulled together via the interface sections 16, 16b, which is indicated by the arrow 31. As a result, the hollow cylindrical element 30 contracts, as a result of which, in particular, the maximum radius is also reduced. Figure 9 It is apparent that the hollow cylindrical element 30 has a conical section 24, which functions similarly to Figure 6bThe function of the tapered section 24 is shown in FIG. During contraction, a substantial portion of the lateral inner surface of the hollow cylindrical element 30 contacts the lateral outer surface of the rotating shaft element 2, thereby establishing a braking state. By setting a corresponding voltage change at the piezoelectric element 6 to force the bridges 26 apart, a released state can be generated, wherein the contact area between the lateral inner surface of the hollow cylindrical element 30 and the lateral outer surface of the rotating shaft element 2 is smaller than in the braking state, in particular by more than 90%. Preferably, no section of the lateral inner surface of the hollow cylindrical element 30 bears against the lateral outer surface of the rotating shaft element 2.

[0164] Figure 10 Shown Figure 9 Schematic longitudinal section of the embodiment shown in FIG. The illustration shows the rotary axis element 2 rotatably mounted in the mounting device 4. Furthermore, the illustration shows the hollow cylindrical element 30 and the frame element 8 in the released state. It is obvious that a portion of the frame element 8 and therefore a portion of the piezoelectric element 6 protrudes into the rotary axis element 2 configured in a hollow cylindrical manner.

[0165] Figure 11 A schematic block diagram of a coordinate measuring machine 32 according to the present invention is shown, which is used to measure a measurement object 33. By way of example, the coordinate measuring machine 32 includes a sensor 34, which is fixed to the rotating axis element 2 via a fixing arm 35. To measure the measurement object 33, the sensor 34 is rotated about the axis of rotation of the rotating axis element 2. The coordinate measuring machine 32 includes a schematically illustrated drive device 36 for generating a drive torque for the rotational movement of the rotating axis element 2. Furthermore, the coordinate measuring machine 32 includes a device 1, which is only schematically illustrated, for braking the rotating axis element 2.

[0166] Furthermore, the illustration shows a control device 37 of the coordinate measuring machine 32 and a device 38 for providing an operating voltage to the piezoelectric element 6 (not shown) of the device 1 .

[0167] The control device 37 can determine a target braking torque / target braking force and then control the device 38 based on this target braking torque so that the voltage applied to the piezoelectric element 6 is set so that the actual braking torque then generated corresponds to the target braking torque or deviates from the target braking torque by only less than a predetermined amount.

[0168] therefore, Figure 11An exemplary embodiment of a coordinate measuring machine 32 is shown, which has two parts that are movable relative to each other and a device 1 for braking relative movement, which includes at least one piezoelectric element 6 for generating a braking force. The coordinate measuring machine 32 also includes a control device 37 and a device 38 for supplying a voltage to the piezoelectric element 6, wherein the control device 37 determines a target braking force and controls the device 38 for supplying a voltage so that the voltage assigned to the target braking force is applied to the piezoelectric element 6.

[0169] Figure 12 A schematic flow chart of a method according to the invention for braking a relative movement between two parts of a coordinate measuring machine that are movable relative to one another is shown, the coordinate measuring machine having a device 1 for braking the relative movement, the device comprising at least one piezoelectric element 6 for generating a braking force. The braking device 1 can be configured according to one of the embodiments described in this disclosure.

[0170] In a first step S1, a target braking force is determined, particularly depending on the current or desired operating state (braking state, partial braking state, released state). In a second step S2, a voltage is applied to at least one piezoelectric element 6 of device 1 in order to set a target braking torque. Specifically, the voltage can be set so that the piezoelectric element generates a target piezoelectric force, which is then converted into a target braking torque via at least one force transmission element.

[0171] In this case, the operating voltage can be provided by a voltage source. The voltage source can in turn be controlled by the control device 37 (see Figure 11 ).

[0172] Furthermore, the voltage may be varied in order to continuously vary the braking force in the second step S2.

[0173] Likewise, in the second step S2 , during the position control mode for setting the relative position of the movable part, a voltage may be applied to the piezoelectric element 6 so that the braking force is smaller than the maximum settable braking force and larger than the minimum settable braking force.

[0174] Furthermore, in the first step S1 , the target braking force may be determined such that a driving force caused by a weight force on a load for the relative movement, whose position and / or orientation can be set by the relative movement, is fully or at least partially compensated.

[0175] For this purpose, before the first step S1 , in particular in a determination step (not shown), the weight of the load can be determined, wherein the weight-induced driving force for the relative movement is determined based on the weight.

[0176] Figure 13A method for braking a rotating shaft element 2 (see for example) according to the present invention is shown. Figure 1 ) shows a schematic longitudinal section of another embodiment of a device 1. The illustration shows a brake disc 5, which (as explained above) is fixed to a rotating shaft element 2. The illustration also shows a piezoelectric element 6, which can be configured as a stacked actuator, and a force transmission element 7, into which the piezoelectric element 6 is clamped. Specifically, the force transmission element comprises two L-shaped profile elements 40a, 40b. One of the legs of each of these profile elements 40a, 40b is connected to a brake shoe carrier element 39, with a first carrier section 39a connected to the leg of the first profile element 40a, and the other carrier section 39b connected to the leg of the other profile element 40b. The carrier sections 39a, 39b are movably connected to one another. A first brake shoe 9a is arranged in / on the first carrier section 39a, and a further brake shoe 9b is arranged in / on the further carrier section 39b. The brake disc 5 extends into the interspace between the brake shoes 9a, 9b. The piezoelectric element 6 is arranged between the other legs of the profile elements 40a, 40b. Figure 13 The piezoelectric element 6 is shown as an elongated actuator extending along the deformation axis D. If the size (length) of the piezoelectric element 6 along the deformation axis D is varied, in particular due to a change in the applied voltage, this results in a change in the distance between the brake shoes 9 a, 9 b in a direction parallel to the axis of rotation, due to the configuration of the force transmission element 7 and the brake shoe carrier element 39 and their arrangement relative to one another.

[0177] If, for example, the size of the piezoelectric element 6 decreases along the deformation axis D, the distance between the brake shoes 9a, 9b decreases. If, for example, the size of the piezoelectric element 6 increases along the deformation axis D, the distance between the brake shoes 9a, 9b increases.

[0178] In order to generate a total clamping force of approximately 400 Nm between the brake shoes 9a, 9b assuming a friction coefficient of 0.1, Figure 13 The piezoelectric element 6 used in the embodiment shown in needs to generate a braking force of approximately 200 N. This can be achieved, for example, using a stacked actuator with a basic area of 5 mm×5 mm and a length of 35 mm.

[0179] Figure 14A schematic diagram shows the heat energy ΔT (in °C) generated by an exemplary piezoelectric element 6 relative to the frequency f (in Hz) of the dimensional change. Circles represent the heat energy generated for a peak voltage of 40 V and a bias voltage of 20 V. Triangles represent the heat energy generated for a peak voltage of 100 V and a bias voltage of 50 V. Squares represent the heat energy generated for a peak voltage of 150 V and a bias voltage of 75 V. It is apparent that, in particular, very small temperature changes of less than 10°C occur at low frequencies in the range below 100 Hz.

[0180] List of Reference Numerals

[0181] 1 device

[0182] 2 Rotating axis elements

[0183] 3. Internal volume of the rotating axis element

[0184] 4Installation device

[0185] 5 brake discs

[0186] 6 Piezoelectric elements

[0187] 7 force transmission elements, clamp elements

[0188] 8 frame elements

[0189] 9, 9a, 9b brake shoes

[0190] 10a, 10b arm sections

[0191] 11a, 11b Surface sections of the brake disc

[0192] 12a, 12b load arm section

[0193] 13 screws

[0194] 14a, 14b lever element

[0195] 15 rotary joint segments

[0196] 16a, 16b interface segments

[0197] 17a, 17b recess

[0198] 18 fixing screws

[0199] 19 stator segments

[0200] 20 holding arm section

[0201] 21 Braking section

[0202] 22 hollow cylindrical elements

[0203] 23 slots

[0204] 24 tapered segments

[0205] 25 arrows

[0206] 26 bridge pieces

[0207] 27 arrows

[0208] 28 spring joint sections

[0209] 29, 29a, 29b spring plate

[0210] 30 hollow cylindrical elements

[0211] 31 arrows

[0212] 32 coordinate measuring machine

[0213] 33 Measuring objects

[0214] 34 sensors

[0215] 35 fixed arm

[0216] 36 drive device

[0217] 37 control device

[0218] 38 means for providing operating voltage

[0219] RRotation axis

[0220] S1 First step

[0221] S2 second step

Claims

1. A method for braking a relative movement between two parts of a coordinate measuring machine (32) that are movable relative to one another, the coordinate measuring machine having a device (1) for braking the relative movement, the device comprising at least one piezoelectric element (6) for generating a braking force, wherein: A target braking force is determined, wherein a voltage assigned to the target braking force is applied to the piezoelectric element (6), wherein, during a position control mode for setting the relative position of the movable part, a voltage is applied to the piezoelectric element (6) so that the braking force is less than a maximum settable braking force and greater than a minimum settable braking force, wherein the partial braking state is set in the position control mode.

2. The method according to claim 1, characterized in that During the position control mode, both the braking force and the driving force / driving torque vary, wherein the change in the braking force depends on the change in the driving force / the driving torque.

3. A method for braking a relative movement between two parts of a coordinate measuring machine (32) that are movable relative to each other, the coordinate measuring machine having a device (1) for braking the relative movement, the device comprising at least one piezoelectric element (6) for generating a braking force, wherein: A target braking force is determined, wherein a voltage assigned to the target braking force is applied to the piezoelectric element (6), wherein a. determining the target braking force so as to fully or at least partially compensate for the driving force caused by the weight force of the load for the relative movement, the position and / or orientation of the load being adjustable by the relative movement, wherein the braking force is set so as to prevent a relative position change caused by pure weight force, but a relative position change caused by the driving force is possible, b. setting the target braking force based on at least the inertia of the load, c. The target braking force is set according to the difference between the target relative position and the actual relative position of the movable parts.

4. The method according to any one of claims 1 to 3, characterized in that The voltage is varied to continuously vary the braking force.

5. The method according to claim 3 or any claim dependent thereon, characterized in that During a position control mode for setting the relative position of the movable part, a voltage is applied to the piezoelectric element (6) so that the braking force is smaller than a maximum settable braking force and larger than a minimum settable braking force.

6. The method according to claim 1 or any claim dependent thereon, characterized in that The target braking force is determined so as to completely or at least partially compensate for the weight-force-induced driving force for the relative movement caused by the weight force on the load, the position and / or orientation of the load being set by the relative movement.

7. The method according to claim 6, characterized in that The weight of the load is determined, wherein a driving force caused by the weight force for the relative movement is determined based on the weight.

8. The method according to claim 6 or 7, characterized in that During or after removal of the sensor (34) from the sensor box of the coordinate measuring machine, the weight of the sensor (34) is determined as the weight of the load.

9. A coordinate measuring machine having at least two parts movable relative to each other, at least one device (1) for braking the relative movement, and at least one control device (37), It is characterized in that The device (1) for braking comprises at least one piezoelectric element (6) for generating a braking force and at least one device (38) for supplying a voltage to the piezoelectric element (6), wherein the control device (37) determines a target braking force and controls the device (38) for supplying a voltage so that a voltage assigned to the target braking force is applied to the piezoelectric element (6).

10. A device for braking a rotating shaft element (2), comprising: a. at least one piezoelectric element (6), b. at least one first force transmission element for transmitting the piezoelectric force generated by the piezoelectric element (6) to the rotating shaft element (2), It is characterized in that the first force transmission element is configured as or includes: i. a brake disc (5) which can be fixed to the rotating shaft element (2) for joint rotation and reduces the axial and / or radial portion of the piezoelectric force transmitted by the brake disc (5) to the rotating shaft element (2), or ii. a cylindrical element (22) which can be arranged in the rotating shaft element (2) and is mounted in the rotating shaft element (2) so as to be movable in the axial direction, or iii. A hollow cylindrical element (30), which has an inner volume for receiving the rotating shaft element (2), and is mounted on the rotating shaft element (2) so as to be movable in the axial direction.

11. The device according to claim 10, characterized in that The piezoelectric element (6) is an amplified piezoelectric actuator.

12. The device according to any one of claims 10 and 11, characterized in that The piezoelectric element (6) is coupled to the first force transmission element via at least one further force transmission element.

13. The device according to claim 12, characterized in that The at least one further force transmission element is configured as a pliers element (7).

14. The device according to claim 13, characterized in that The pliers element (7) is configured as a single-sided pliers element.

15. The device according to any one of claims 10 and 11, characterized in that The cylindrical element (22, 30) of the device having the features of alternative ii or iii of claim 10 is slotted.

16. The apparatus according to claim 10, 11 or 15, characterized in that The cylindrical element (22, 30) of the device having the features of alternative ii or iii of claim 10 has a conical section (24).

17. The apparatus according to claim 10, 11, 15 or 16, characterized in that The cylindrical element (22) of the device having the features of alternative ii or iii of claim 10 has a spring joint section (28).

18. The apparatus according to any one of claims 10 to 17, characterized in that The rotary axis element is part of a coordinate measuring machine.

19. The apparatus according to any one of claims 10 to 14, characterized in that The stiffness of the brake disc of the device having the features of alternative i. of claim 10 in the axial direction is lower than the stiffness of the brake disc in the tangential direction at a point on a circle line around the axis of rotation.

20. The apparatus according to any one of claims 10 to 14 or 19, characterized in that The piezoelectric force is transmitted via at least one front side surface and a rear side surface of a brake disc of an apparatus having the features of alternative i of claim 10, wherein a first brake element is provided for actuating the front side and a second brake element is provided for actuating the rear side, wherein the actuating sections are arranged at different radial distances on the front side and the rear side.

Images