Monitoring device, clamping system having a monitoring device, and method for monitoring a clamping device using a monitoring device

Abstract

The invention relates to a monitoring device (12) for monitoring the clamping quality of a workpiece carrier clamped in a clamping device (3, 40, 49) and a clamping system comprising a clamping device (3, 40, 49) and such a monitoring device (12). The monitoring device comprises at least two sensors (A1-A4) for independently detecting the clamping quality of the clamped workpiece carrier or the workpiece. The monitoring device further comprises a transmitting device (14) and a receiving device (21), wherein the transmitting device (14) is designed such that it redundantly transmits one or more determined or calculated parameters to the receiving device (21).

Description

Technical Field

[0001] The invention relates to a monitoring device according to the invention, a clamping system according to the invention having a monitoring device, and a method for monitoring a clamping device by means of the monitoring device according to the invention. Background Art

[0002] Using a monitoring device of the type discussed here, the clamping device is to be monitored, in particular with regard to whether a workpiece carrier-pallet clamped by the corresponding clamping device or a workpiece clamped in a workpiece carrier-pallet is clamped correctly and securely, wherein one or more measured parameters are to be transmitted wirelessly to a receiver.

[0003] A chuck is known from EP 3 391 991 A, which is designed for clamping a pallet provided with a clamping sleeve. The chuck is provided with a positioning hole for the clamping sleeve and a clamping device comprising a clamping element for clamping the clamping sleeve in the positioning hole. At least one sensor is arranged on the chuck, by means of which at least one parameter of the chuck and / or the interaction between the pallet and the chuck and / or the pallet can be detected. The chuck is provided with a transmitter for wireless transmission of the parameters determined by one or more sensors. The clamping force acting on the clamping sleeve can be determined by a first sensor. For this purpose, the first sensor is designed and arranged on the chuck so that the elastic deformation of the material of the chuck can be measured when the pallet is clamped. The chuck can also be provided with a second sensor, by means of which the installation of the pallet on the chuck can be detected.

[0004] EP 1 998 932 B1 discloses a chuck with a three-jaw chuck. The chuck comprises a rotationally symmetrical base body with a conical positioning hole for receiving the chuck. A draw tube, which is part of the machine spindle, is provided to pull the chuck into the positioning hole. This chuck is particularly suitable for lathes. A first sensor is arranged on the outer surface of the chuck body, a second sensor is arranged in a recess in the outer surface of the chuck body. Finally, a third sensor is arranged on the draw tube. These sensors are designed as strain gauges, each equipped with an integrated signal processing unit. Each signal processing unit is assigned a transmission device for wirelessly transmitting the measured values. This embodiment of the chuck is intended to enable the clamping force of the chuck to be determined. When the minimum clamping force is reached, the chuck must be serviced. The axial positioning of the workpiece is not monitored and cannot be determined. There is no signal indicating the presence of the workpiece. Any errors that may occur in the wireless transmission are also not detected.

[0005] A clamping device with a chuck for releasably securing a workpiece carrier is known from EP 2 052 808 A1. The chuck is provided with a locking mechanism comprising a plurality of clamping elements which, in the locked position, engage with a clamping sleeve connected to the workpiece carrier. Each clamping element is provided with a through-hole which is closed at one end when the respective clamping element is correctly locked. Additionally or alternatively, an actuating element is assigned to each clamping element and provided with a through-hole which is closed at one end when the respective clamping element is correctly locked and / or unlocked. The through-holes of the clamping elements or actuating elements are connected to a pneumatic source via a common connecting line. At least one sensor for detecting the air flow is provided in the connecting line. The sensor can be used to detect whether the clamping element has been correctly unlocked or locked. The sensor is connected to an electronic control and evaluation device.

[0006] Furthermore, EP 2 759 372 A1 discloses a clamping device for a machine tool. The machine tool includes a rotatable spindle with a tool-holding fixture for a tool. The clamping device is configured to clamp the tool. To detect whether the tool is correctly or incorrectly clamped in the tool-holding fixture, the clamping device includes force sensors at different measuring points to detect the clamping forces acting at the different measuring points. The force sensors are arranged on an annular seat surface of the tool-holding fixture. The sensors protrude above the seat surface so that they are compressed when the tool is clamped. Therefore, it should be possible to detect the clamping force and whether the tool is correctly clamped or whether there may be misalignment and / or incorrect positioning. An AOW sensor (surface acoustic wave sensor) is used as the force sensor. The force sensor is arranged on a seat surface that is rotationally symmetrical about the central axis of the machine tool. When the tool is correctly aligned, the force sensor detects equal clamping forces, but when the tool is clamped at an angle, the force sensor detects different clamping forces. The electrical signals from the sensors are wirelessly transmitted to a transmitting and receiving unit and evaluated in an evaluation unit.

[0007] EP 2 093 016 A1 describes an intelligent multi-part clamping device. The clamping device comprises multiple clamping jaws arranged on a base plate, wherein the fixed and displaceable clamping jaws each form a vise. Workpiece mounting sensors or ram-air workpiece mounting controls are located in the clamping jaws, the former being connected to a radio module via a cable. Correct insertion into the clamping jaws is monitored by the sensors.

[0008] EP 3 028 804 A1 describes a transmission device, particularly for energy and / or signal transmission and for use in machining centers. Signals and voltages are inductively transmitted from a fixed machine frame to a rotating chuck, both in the direction of the chuck and vice versa. Each chuck has a clamping jaw that is displaceably supported in the chuck body by an electric motor. When a predefined actual position is reached, the electric motor is switched off, and the clamping jaw is stopped by a spring assembly and a mechanical friction brake. During the clamping process, the electric motor compresses the spring assembly, which applies the clamping force to the jaw. After the electric motor is switched off, the mechanical friction brake prevents the jaw from slipping or releasing. Furthermore, the position of the jaw is permanently monitored during machining operations to detect machining errors or even the release of the clamped workpiece. To enable permanent monitoring of the corresponding operating state and position of the jaws and / or electric motor, the jaws and / or electric motor are assigned a number of measuring sensors that generate corresponding measurement data and transmit this data via an inductive transmission device. The inductive transmitter is designed in two parts, on the one hand in the rotating chuck and on the other hand in the fixed carrier frame. The two transmitters are aligned flush with one another, so that due to the spatial separation of the two transmitters, the chuck can be rotated and simultaneously measurement signals, measurement data, and / or voltage for operating the electric motor can be inductively transmitted.

[0009] EP 3 620 248 A1 discloses a coupling device that can inductively transmit data from a rotatable part to a rotationally fixed part. Specifically, a rotating chuck can be connected to a customer-side control system during operation and monitored via the coupling device. The chuck includes radially displaceable jaws to secure the workpiece. Each jaw is driven by an associated electric motor. To provide energy for the rotating chuck during machining operations on the clamping table, a first transmission device is provided in the chuck, which is connected via electrical wiring to the electric motor and a measuring sensor. The position of the jaws and the voltage or speed of the electric motor are measured by the measuring sensor. A second, rotationally fixed transmission device is mounted on a supporting frame. Measurement data is inductively transmitted from the first, rotatable transmission device to a second, rotationally fixed transmission device. The second transmission device is connected via electrical wiring to a programmable interface. A variant of the chuck provides two interfaces connected to the second transmission device. These two interfaces independently receive and evaluate measurement data sets from the measuring sensor. If the measurement results of the two interfaces are consistent, the control device receives a release signal, while in the event of inconsistent measurement results, the machining operation is interrupted or not released.

[0010] Finally, EP 2 457 688 A1 discloses a method for positioning and fixing a workpiece. The presence or absence of a workpiece or a workpiece carrier can be determined by a process step. Summary of the Invention

[0011] The problem underlying the present invention is to create a monitoring device belonging to the technical field mentioned at the outset for monitoring the clamping quality of a workpiece carrier or a workpiece clamped in a clamping device, which monitoring device enables one or more parameters, in particular parameters such as parameters from which information can be inferred to ensure the clamping of the clamped workpiece carrier or the workpiece, to be reliably detected on the one hand and to be transmitted safely and reliably to a receiver on the other hand without the need for a data line.

[0012] The solution to this problem is defined by the features described in the present disclosure. According to the invention, a monitoring device for monitoring the clamping quality of a workpiece carrier or a workpiece clamped in a clamping device comprises at least two sensors for independently detecting the clamping quality of the clamped workpiece carrier or the workpiece, wherein the sending device is designed so that it redundantly sends one or more determined or calculated parameters to the receiving device. Due to the fact that at least two sensors are provided for independently detecting the clamping quality of the clamped workpiece carrier or the workpiece, errors that may arise from individual sensors can be detected, for example by cross-comparison of the measurement data. By redundantly sending the measurement data from the sending device to the receiving device, errors on the transmission link can also be detected and eliminated as required.

[0013] Preferred embodiments and improvements of the monitoring device are described in other parts of this disclosure.

[0014] Therefore, in a preferred embodiment, the monitoring device includes at least one sensor module, via which the measured values ​​present at the sensor are digitized and transmitted to the transmitting device. This preparation of the measured data increases reliability and simplifies the transmission of the measured values ​​to the transmitting device. Furthermore, if applicable, the corresponding sensor module can also be used to supply power to the sensor or sensors.

[0015] In a particularly preferred embodiment of the monitoring device, the transmission device is equipped with two independent microprocessor units, which are configured to independently and redundantly prepare the measured values ​​transmitted by the respective sensor module. This embodiment facilitates immediate detection of errors in the messages and, if necessary, checks on the plausibility of the measurements. Furthermore, the different and independent microprocessors can also be programmed differently, which is advantageous for detecting and processing redundant measurement data.

[0016] The transmitting device preferably comprises at least one transmitting antenna for transmitting the measurement data prepared by the two independent microprocessor units. The measurement data can be wirelessly transmitted to the receiving device via the transmitting antenna, and the above components can be combined in a compact and power-saving component.

[0017] Very particularly preferably, the monitoring device comprises at least two sensors which are arranged such that their measured values ​​are positively correlated with one another. This enables a particularly direct check of the correctness of the measured values, since the detected measured values ​​can be compared with one another by cross-comparison.

[0018] The monitoring device particularly preferably comprises at least two sensors designed and arranged such that the elastic deformation of the material of the chuck or the vise of the clamping device can be measured during clamping of the workpiece carrier or the workpiece, wherein the sensors are in particular strain gauge sensors (DMS). DMS sensors are characterized by their high precision and good long-term stability, so that information about the actually existing clamping force can be very easily inferred from this arrangement of sensors.

[0019] A preferred development of the monitoring device serves to monitor a clamping device having at least one chuck, which comprises an actuating piston displaceable in the Z direction in its interior for actuating a clamping element for clamping a clamping sleeve. The monitoring device comprises at least two contactless sensors, by means of which at least two positions, preferably at least three positions, of the actuating piston can be detected independently of one another. This embodiment makes it possible to reliably monitor different states of the chuck using two sensors, with inductive sensors being particularly preferred.

[0020] In a further preferred embodiment, the monitoring device includes at least one further sensor, by means of which the installation of the workpiece carrier on the clamping device can be detected. Such a sensor can detect whether the workpiece carrier is actually located directly in the set position on the Z-shaped support of the clamping device, or whether it is located on dirt (such as swarf, for example) and is therefore not positioned correctly in the Z direction.

[0021] Another embodiment of the monitoring device serves to monitor the clamping quality of a workpiece clamped in the vise of the clamping device. The monitoring device in this preferred embodiment includes at least two further sensors, which can detect the attachment of the workpiece to the corresponding guide blocks of the vise. This makes it possible to detect whether the workpiece is clamped correctly or, for example, tilted.

[0022] A preferred refinement of the monitoring device further provides that the monitoring device is equipped with an additional sensor by means of which the position of an element for actuating the clamping element can be detected. This embodiment is particularly important for the automatic feeding or removal of workpiece carriers by robots, since the aforementioned element must be in its initial position or open position for actuating the clamping element in order to allow the workpiece carrier to be fed or removed.

[0023] In a particularly preferred embodiment, the monitoring device comprises a receiving antenna for receiving the data transmitted by the transmitting device and a gateway connected to the receiving antenna, wherein the gateway is provided with two independent microprocessor units, by means of which the received data are processed further independently and redundantly in each case, and wherein the gateway is connected to the machine control of the processing machine. This embodiment contributes to the fact that data can be reliably received and transmitted to the machine control of the processing machine via the gateway.

[0024] In a particularly preferred embodiment of the monitoring device, the gateway processes the measured values ​​transmitted by the transmitting device so that, upon determining that the detected measured values ​​are consistent and have reached predetermined measured values ​​of the machine control, a signal is redundantly output to the machine control for a correctly clamped workpiece carrier or a correctly clamped workpiece and / or for reliable operation of the machine tool. Reliable operation of the processing machine can thus be ensured, since the release signal is only present when the workpiece carrier or the workpiece is securely and correctly clamped.

[0025] A further object of the present invention is to develop a clamping system having a clamping device for clamping a workpiece carrier or a workpiece and a monitoring device according to the invention, such that it is possible to reliably detect whether the workpiece carrier or the workpiece is securely clamped.

[0026] This problem is solved by the clamping system according to the present invention. Since the monitoring device of the clamping system is equipped with at least two sensors, which are arranged in the clamping device for independently detecting the clamping force acting on the clamped workpiece carrier or the clamped workpiece, the measured value related to the secure clamping of the workpiece carrier or the workpiece is detected twice and independently of each other. This creates the basic prerequisite for reliably detecting whether the workpiece carrier or the workpiece is securely clamped.

[0027] Preferred developments of the clamping system are defined in the remainder of this disclosure.

[0028] The clamping system is preferably designed in such a way that the transmitting device of the monitoring device comprises a radio transmitter arranged on the clamping device, and the receiving device comprises a radio receiver arranged remotely from the clamping device, wherein the transmitting device comprises two independent microprocessor units configured to prepare the measured values ​​transmitted independently and redundantly by the individual sensor modules and to check their plausibility by cross-comparison of the measured data. Thus, redundant pre-processing of the measured data for plausibility can already be performed on the transmitter side, i.e., in or on the clamping device.

[0029] According to a particularly preferred example of embodiment of the clamping system, strain gauges are used as sensors, which are frictionally engaged and / or firmly bonded to the chuck or vise of the clamping device, such that their signal is substantially proportional to the clamping force. Due to their high precision and good long-term stability, DMSs are particularly advantageously suitable for providing precise information about the clamping force acting on the workpiece carrier or workpiece by measuring the material deformation on the chuck or vise, and thus providing precise information about the clamping quality.

[0030] In another preferred embodiment of the clamping system, its clamping device comprises at least one chuck for clamping a workpiece carrier, wherein the chuck comprises a sensor arranged in the upper region for detecting the installation of the workpiece carrier. This sensor can be used to determine the exact Z position of the workpiece carrier, which is important, for example, with regard to possible dirt in the Z support region.

[0031] A particularly preferred embodiment of the clamping system comprises a chuck for clamping a workpiece carrier, which is provided with a clamping sleeve, wherein the chuck is provided with an actuating piston that can be displaced between an initial position and a locking position for actuating a clamping element for clamping the clamping sleeve, and the chuck is provided with a further sensor for monitoring the position of the actuating piston. Detecting the position of the actuating piston is particularly important for automated assembly of the clamping system by means of a handling robot, in particular to prevent undesirable damage.

[0032] A particularly preferred embodiment of the clamping system comprises at least two chucks for clamping a workpiece carrier, the workpiece carrier being provided with a number of clamping sleeves corresponding to the number of chucks, wherein each chuck is provided with an actuating piston displaceable between an initial position and a locking position for actuating a clamping element for clamping the respective clamping sleeve, and wherein at least one chuck is provided with an additional sensor for monitoring the position of the actuating piston. Due to the fact that the position of the at least one actuating piston is monitored, information can also be derived as to whether the workpiece carrier can in principle be advanced or removed.

[0033] In an alternative embodiment of the clamping system, the clamping device is designed as a vise with two clamping jaws, wherein each clamping jaw is assigned a sensor for determining the clamping force of the clamped workpiece. Due to the fact that the clamping force is determined by both clamping jaws, it is possible to infer whether the workpiece is securely clamped.

[0034] Finally, a further problem of the present invention is to develop a method for monitoring the clamping device of a processing machine by means of a monitoring device according to the invention, so that it can be reliably determined and in a direct manner whether the clamping quality of the clamped workpiece carrier or workpiece meets certain requirements, wherein the control of the processing machine and / or the associated handling robot can be influenced based on the measured values.

[0035] This problem is solved by the method according to the invention. Due to the fact that the clamping quality of the workpiece carrier or workpiece clamped in the clamping device is determined by at least two independent sensors, the fact that the measurement data determined by the respective sensors are compared with one another and checked for plausibility, and the fact that the determined or calculated parameter or parameters are redundantly transmitted to the receiving device via the transmitting device and the control of the processing machine is influenced based on the existing measured values, reliability can be ensured during the processing of the workpiece clamped on the processing machine by the clamping device or workpiece carrier.

[0036] Preferred refinements of this method are defined elsewhere in this disclosure.

[0037] In a particularly preferred method, the plausibility check includes checking the consistency of the parameters determined and compared with each other after the parameters have been prepared by two independent microprocessor units of the transmission device. In addition to the double detection of the measured values ​​relevant for secure clamping, a redundant evaluation is thus provided.

[0038] In a particularly preferred embodiment of the method, the determined or calculated parameter or parameters are transmitted redundantly by the transmitting device to the receiving device in the form of data packets, wherein the transmitted data are checked on the receiving end for plausibility. This allows errors on the radio link to be detected.

[0039] Another preferred method provides that, when the determined and compared parameters agree and reach a predetermined measured value, a release signal for safe operation is generated by the gateway and redundantly transmitted to the control device of the processing machine. Thus, the release signal is only issued when the prerequisites for reliable operation of the processing machine are met, i.e., when the workpiece carrier or the workpiece is securely clamped.

[0040] Finally, in a highly preferred refinement of the method, the gateway emits the release signal in the form of a binary signal, wherein the release signal assumes the value 1 if the detected measured value is plausible and reaches a predetermined value, and wherein the release signal assumes the value 0 if the detected measured value is implausible or does not reach the predetermined value. This achieves positive reliability, since the release signal assumes the value 1 only when the workpiece carrier or workpiece is correctly and securely clamped. In the event of a fault, such as a power failure, for example, the release signal automatically assumes the value 0, which is immediately detected by the machine control and causes the machine to stop or at least generates an error message.

[0041] Further advantageous embodiments and combinations of features of the invention emerge from the overall outline of the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The figures of the drawings, used to explain examples of embodiments, show:

[0043] Figure 1 A schematic diagram shows a first clamping device together with a monitoring device;

[0044] Figure 2 A perspective view shows the second clamping device together with the workpiece carrier and individual components of the monitoring device;

[0045] Figure 3a It is based on Figure 2 A cross-sectional view of the clamping device together with a workpiece carrier shown as elevated;

[0046] Figure 3b The cross-sectional view shows the Figure 3a A clamping device together with a workpiece carrier clamped thereon;

[0047] Figure 3c Is the basis for penetrating without workpiece bracket Figure 2 Another cross-sectional view of the clamping device;

[0048] Figure 4 A perspective view shows a third clamping device, which is designed as a vise together with the individual components of the monitoring device. DETAILED DESCRIPTION

[0049] Figure 1 A schematic diagram shows a clamping device 3 together with a monitoring device 12. A first rectangle 1 schematically indicates a machine space in which a processing machine, on which the clamping device 3 is used, stands. The clamping system is represented by a dotted line 2 and comprises the clamping device 3 and part of the monitoring device 12. The clamping device 3 in this example is a so-called quadruple chuck, in which four chucks 6, 7, 8, and 9 are arranged on a base plate 5. Each chuck has a central locating hole (not shown) for receiving and clamping a clamping sleeve arranged on a workpiece carrier (not shown). In order to clamp the clamping sleeve in the locating hole, each chuck 6, 7, 8, and 9 is provided with a clamping mechanism. The upper sides of the four chucks form the XY plane of the chuck, with the so-called Z axis perpendicular to it. Since such chucks are generally known, for example from EP 3391991 A or DE 102013014036A1, each chuck is only schematically represented and only relates to some features relevant to the present invention.

[0050] In addition to a plurality of sensors for detecting the clamping quality of the clamped workpiece carrier, the monitoring device 12 includes a transmitting device 14 and a receiving device 21, indicated by dashed lines. In this example, three sensors A1, B1, C1; A2, B2, C2; A3, B3, C3; and A4, B4, C4 are assigned to each chuck 6, 7, 8, 9, whose functions will be described in more detail below. The three sensors A1-C1; A2-C2; A3-C3; and A4-C4 of the respective chuck 6, 7, 8, 9 are each connected to a sensor module 34, 35, 36, 37, which prepares the measured values ​​measured by the respective sensor. The respective sensor module is responsible for supplying the sensors (strain gauges or Wheatstone bridge circuits, inductive sensors, etc.) with power. On the other hand, an integrated A / D converter digitizes the analog measurement signals so that the measurement data can be transmitted digitally via relatively few lines L1-L4. Ideally, each sensor module 34, 35, 36, 37 is sent via one line to the transmission device 14. The transmission device 14 is equipped with two independent microprocessor units 15, 16, which preprocess the measurement data. The two microprocessor units 15, 16 are preferably equipped with different microprocessors to ensure independent and redundant preparation of the measurement data. The transmission device 14 is also equipped with a radio module (radio transmitter) and a transmitting antenna 17 for wireless transmission of the measurement data. In this example, the transmitting antenna 17 is configured to transmit the measurement data prepared by the two microprocessor units 15, 16. Furthermore, the clamping system 2 is equipped with an acceleration sensor 18, which, as shown here, can be arranged in the area of ​​the transmission device 14.

[0051] For powering the transmitter 14, a power source 19 is used, preferably in the form of batteries or accumulators, which can be housed, for example, in a separate battery compartment (neither of which is shown in detail) in the clamping device 3. Alternatively, a power pack, an inductive power supply, or a device for converting energy from the environment (energy harvesting) can be provided.

[0052] The receiving device 21, a radio receiver, arranged remote from the clamping device 3, includes, in addition to a receiving antenna 22, a gateway 24 for preparing the data. The well-known and used technical term gateway refers to a switching device, in particular a transmission point in a switching device in a computer network. In computing, a gateway is understood to mean a component (hardware and / or software) that creates a connection between two systems. The gateway 24 also includes two independent microprocessor units 25, 26 for evaluating the received data. Here, the two microprocessor units 25, 26 are preferably also provided with different microprocessors to ensure independent and redundant processing of the received measurement data. The different and independent microprocessors can also be programmed with different software, which in turn helps to increase reliability.

[0053] The receiving antenna 22 is connected to a gateway 24 via a first cable 23. The gateway 24 itself is connected to a machine control device 28 via a second cable 27. The machine control device 28 is connected to a handling robot 30 via a third cable 29. The gateway 24 is also connected to a maintenance tool 32 via a fourth cable 31. Although the gateway 24 is shown here outside the circuit 2 representing the clamping system, it typically also forms an integral part of the monitoring device 12 and is assigned to the clamping system. The clamping device 3 can be fed or removed by the handling robot 30. The machine control device 28 controls the processing machine on which the clamping device 3 is used. Finally, the maintenance tool serves as a calibration and diagnostic tool. Although the cables 23, 27, 29, and 31 described above are each schematically represented here by lines, the term cable in this connection refers to any type of electrical connection, including single-core and multi-core wires, as well as multiple independent lines. Thus, the gateway 24 is connected to the machine control device 28, for example, via at least two lines, as will be explained in more detail below.

[0054] The gateway 24 receives the data digitally transmitted by the transmitting device 14 via the antenna 22 and evaluates it. For wireless data transmission, standardized interfaces such as, for example, Bluetooth, ZigBee or proprietary radio transmitters in the 2.4 GHz frequency range are preferably used, with the use of Bluetooth Low Energy (BLE) radio technology being very particularly preferred, as explained in more detail below.

[0055] Based on the transmitted data, the gateway 24 can detect the status of the clamping device, such as, for example, chuck open, no pallet present, pallet in place, pallet clamped, pallet clamped at 10 kN, etc., and can relay this status to the machine control device 28 or the process control system connected thereto. The machine control device 28 or the process control system can send instructions to the handling robot 34, such as transferring a workpiece carrier to the clamping device 3 or removing a workpiece carrier from the clamping device 3. In the event of a malfunction or the detection of insufficient mechanical clamping, in particular during the processing of a workpiece carrier clamped in the clamping device 3, the corresponding processing machine can be stopped immediately. In all cases, the control of the processing machine and / or the associated handling robot can be influenced based on the measured values ​​present at the sensor.

[0056] Of the three sensors in each chuck 6, 7, 8, 9, the first sensor A1, A2, A3, A4 is used to determine the clamping force with which the clamping sleeve is clamped in the respective chuck. For this purpose, preferably a strain gauge-based sensor, hereinafter referred to as DMS, is used, which measures the elastic deformation of the material of the chuck, in particular the housing. This allows information to be drawn about the force with which the clamping sleeve is drawn into the respective chuck or clamped therein.

[0057] In each case, another sensor B1, B2, B3, B4 is used, on the one hand, to check the presence of a workpiece carrier. On the other hand, the exact Z position of the workpiece carrier can also be determined by the corresponding sensor B1, B2, B3, B4. For this purpose, an inductive sensor is preferably used, which is arranged in the upper area of ​​the chuck 6, 7, 8, 9 so that it detects the presence or installation of the workpiece carrier.

[0058] In each case, another sensor C1, C2, C3, or C4 is used to monitor the position of the actuating piston for actuating the clamping element. The actuating piston pushes the clamping element (clamping ball) used to clamp the clamping sleeve radially inward, causing it to frictionally lock against the clamping sleeve. When the clamping element is pushed radially inward by the actuating piston, the actuating piston is in the activated position. If the actuating piston is pushed into the initial position, the clamping elements are in the open position or at least can be pushed back into the open position. Therefore, in the open position of the actuating piston, the clamping sleeve can be introduced into or removed from the chuck, while in the locked position of the actuating piston, the clamping elements are in a clamped position in which the clamping sleeve is clamped in the chuck. If the actuating piston is in the locked position, the clamping sleeve cannot be inserted into or removed from the chuck. In the case of such chucks, the actuating piston is typically pneumatically operated, wherein it is pneumatically moved into the open position, and then pushed into the locked position by a spring action and held there by self-retention. This has the advantage that the chuck is locked in the pressure-free state, so that the workpiece carrier can be firmly clamped and remains firmly clamped even without compressed air.

[0059] It goes without saying that each chuck 6, 7, 8, 9 does not necessarily have to be provided with three sensors. Instead, depending on the requirements, one, two, or three sensors per chuck may be sufficient. If appropriate, it may even be sufficient to provide sensors at only two of the four chucks in each case. In this case, the sensors are preferably arranged at two chucks 6, 8 or 7, 9 that are diagonally opposite one another, and can measure the clamping force with which the respective clamping sleeve is clamped in the chuck.

[0060] Finally, the acceleration sensor 18 is used to determine the position of the clamping device 3. Furthermore, the movement of the clamping device 3 can be monitored by the acceleration sensor 18. Thus, for example, vibrations occurring during the machining of a workpiece can be continuously monitored and the machining operation can be stopped immediately if limit values ​​are detected to be exceeded.

[0061] Bluetooth Low Energy (BLE) technology is particularly preferred for radio transmission, requiring very little transmission energy and having a range of approximately 10 meters. Furthermore, BLE is an internationally standardized radio interface and can therefore be used worldwide at a frequency of 2.4 GHz. Since BLE is also used in smartphones, for example, the corresponding components can be manufactured in very large quantities and thus be obtained at a favorable cost. For example, a smartphone can thus also communicate with the chuck. Therefore, this technology offers numerous advantages, for example, compared to the inductive transmission used in EP 3 028 804 A1.

[0062] Several possible functional modes of the monitoring device are explained below.

[0063] Example 1

[0064] In this example, it is assumed that only one sensor is provided in each case per clamping disc 6 , 7 , 8 , 9 , namely a DMS sensor A1 , A2 , A3 , A4 for measuring the prevailing clamping force.

[0065] Once the workpiece carrier (not shown) is clamped in the clamping device 3, data is measured by the DMS sensors A1, A2, A3, and A4. The data digitized in the sensor modules 34, 35, 36, and 37 is processed in parallel in the two microprocessor units 15 and 16 of the transmitter 14. The measurement data of the various sensors are processed independently of one another by the two microprocessor units 15 and 16, and their plausibility is checked by cross-comparison of the measurement data. The measured values ​​of the four DMS sensors A1, A2, A3, and A4 may deviate from each other by no more than a predetermined value. If the determined measured values ​​are within a predefined tolerance window, the measured values ​​are transmitted by the transmitter 14 to the receiver 21. However, if the measured values ​​differ significantly from one another, an error may have been detected on the transmitter side, and an error message may be output, if desired. The measured values ​​may still be transmitted to the receiver 21.

[0066] In addition to the aforementioned cross-comparison of measured values, by which the plausibility of the measured values ​​is determined, the absolute measured values ​​are of course also used to determine whether the workpiece carrier or the workpiece is clamped correctly and with the required clamping force.

[0067] Preferably, the measured or determined data are checked for plausibility before being sent and again for plausibility after being sent.

[0068] Due to the fact that the measured data, such as the clamping force measured by DMS sensors A1, A2, A3, and A4, are positively correlated, the two microprocessor units 15 and 16 compare and check the plausibility of the measured data. Preprocessing of the measured data can already be performed in the transmitter 14, and if necessary, a reduced amount of data can be sent to the receiver 21. If the measured data are plausible, they are transmitted by the transmitter 14 to the receiver 21. If implausible measured data are detected, an error message is sent. In addition to the error message, the measured data can also be sent if necessary. If the measured value is plausible, the actual measured value (i.e., the clamping force used to clamp the corresponding clamping sleeve in the chuck) can be sent, or alternatively, a reduced amount of data indicating "normal clamping" can be sent. It may be sufficient to detect only the measured values ​​from two diagonally opposite sensors and check their plausibility. However, if the data from all four DMS sensors A1, A2, A3, and A4 are determined and checked for plausibility, it can also be ensured that all four clamping sleeves are present on the workpiece carrier and are not missing.

[0069] In order to prevent transmission errors on the radio link, which may occur, for example, due to message corruption, unintentional duplication of messages, incorrect message sequence, message loss, time delay of messages, insertion of corrupted information, for example due to malfunctions or due to an incorrect sender, appropriate measures must be taken.

[0070] The measurement data are preferably transmitted redundantly and in the form of digital data packets. The individual data packets can be provided with a secure, anti-aliasing encoding so that a corresponding allocation can be made on the receiver side.

[0071] At the receiver side, the data packets are received by the antenna and evaluated by two microprocessor units 25, 26 of the gateway 24. The sent measurement data are also preferably checked for plausibility by a cross comparison at the receiver side. In addition to the cross comparison, the absolute measured values ​​must also be used to determine whether the clamping is correct.

[0072] In order to ensure reliable reliability, a clamping signal - a release signal - is generated by the gateway 24 when correct clamping is detected, which is monitored by the machine control. Correct clamping means, on the one hand, the plausibility of the existing measured values ​​is detected by cross-comparison, and on the other hand, a predetermined minimum clamping force is reached. The gateway preferably sends the release signal in the form of a binary signal, wherein the release signal takes the value 1 when the detected measured value is plausible and reaches the predetermined value, and wherein the release signal takes the value 0 when the detected measured value is not plausible or does not reach the predetermined value. When the two microprocessor units 25, 26 detect correct clamping, two release signals with the value 1 are generated independently of each other by the two microprocessor units 25, 26 of the gateway 24. The machine control is connected to the gateway 24 via two lines to send the release signal, and only when the release signals of both lines take the value 1 is correct clamping detected by the machine control 28. The release signal is therefore sent redundantly (twice) to the machine control 28.

[0073] If the gateway 24 detects an inadmissible error in the transmission link, an error is also generated and the release signal assumes the value 0. This results in the machine control system stopping the processing machine. In the event of a fault in the receiving device (electronics) or other malfunction (such as a power failure or an implausible measured value), the release signal also assumes the value 0, so that the machine control system 28 again stops the processing machine.

[0074] Particularly preferably, the data are enhanced with redundant information during wireless transmission in order to detect corruption and / or errors. Due to the measures taken, errors and / or corruption can be detected early on, and not just at the end.

[0075] Although the transmitting device 14 and the receiving device 21 have been mentioned separately before, the unidirectional transmission of data from the transmitting device 14 to the receiving device 21 does not exclusively occur, but data can also be transmitted in the opposite direction, as explained before.

[0076] In any case, the measurement data or parameters relevant to secure clamping are detected twice, i.e. redundantly, and the plausibility of these measurement data is checked by a cross-comparison on the transmitter side by means of the monitoring device designed according to the invention via two independent microprocessor units 15, 16. These measurement data are then double-checked and redundantly evaluated again on the receiver side via two independent microprocessor units 25, 26 of the gateway 24, and finally redundantly transmitted again to the machine control device 28. Thus, double protection measures are included in each of these steps, ultimately resulting in safe and reliable operation of the entire measurement chain, including wireless transmission.

[0077] Example 2

[0078] In this example, the measurement data of all sensors of the clamping device 3 are detected. Preferably, the data from sensors of the same type are compared with one another and checked for plausibility. The DMS sensors can, on the one hand, determine the clamping quality of the clamped workpiece carrier in the manner described above. In principle, in this case, the safety-related measured values ​​are always compared with one another.

[0079] On the other hand, the presence and exact position of the workpiece carrier can be determined by further sensors B1, B2, B3, and B4. These inductive sensors B1, B2, B3, and B4, arranged in the upper area of ​​the respective chucks 6, 7, 8, and 9, can measure the precise distance between the workpiece carrier and the respective sensor. This makes it possible to detect, in particular, whether the workpiece carrier lies flat on the Z-shaped bracket of the clamping device 3 or the respective chuck 6, 7, 8, and 9, and whether there is an undesirable distance between the Z-shaped bracket and the corresponding bracket of the workpiece carrier that could adversely affect the machining accuracy of the workpiece clamped thereon, for example due to dirt. This makes it possible to detect, for example, whether chips are trapped beneath the pallet and are therefore not positioned at the relevant point by, for example, 0.1 mm. If incorrect installation of the workpiece carrier is detected, an error message is issued and the release signal assumes the value 0.

[0080] Another sensor, C1, C2, C3, or C4, monitors the position of the actuating pistons that actuate the clamping elements. Based on the position of the actuating pistons, it is possible to infer whether the actuating pistons are in the open or locked position. This information can be used to determine whether a clamping sleeve can be introduced into or removed from the respective chuck. It can also be used to determine whether a workpiece carrier can be fed or removed by the robot. However, the workpiece carrier must only be fed or removed when the actuating pistons are in the open position.

[0081] Finally, the position of the clamping device 3 can be determined by means of the acceleration sensor 18. The vibrations of the clamping device 3 can also be monitored by means of the acceleration sensor 18.

[0082] Figure 2 A further embodiment of a clamping device 40 together with a workpiece carrier 45 and individual components of a monitoring device is shown in a perspective view. The clamping device is designed here as a single chuck 41. This chuck 41 is provided with a central positioning hole 42 for receiving a clamping sleeve 46 arranged on the workpiece carrier 45. In this example, in addition to a transmitting device 14 arranged on the clamping device 40 and a receiving device 21 arranged remote from the clamping device, the monitoring device comprises two sensors for determining the clamping force, a third sensor 43 for determining the position of the workpiece carrier 45, a fourth sensor for monitoring an actuating piston for actuating the clamping element, and a fifth sensor for determining the position of the clamping device 40, according to Figure 2Any sensors other than the third sensor 43 are not shown in the illustration.

[0083] The first two sensors for determining the clamping force are designed as DMS sensors, which measure the elastic deformation of the material of the chuck 41. The third sensor 43 is an inductive sensor arranged on the upper side of the chuck 41, which can be used to determine the presence or correct installation of the workpiece carrier 45. The fourth sensor is an inductive sensor arranged inside the chuck, which detects the position of the actuating piston for actuating the clamping element, that is, whether the actuating piston is in the open position or the locked position. Finally, the fifth sensor is an acceleration sensor arranged on the clamping device 40, which can detect the position and / or movement of the chuck 41.

[0084] The transmitting device 14 and the receiving device 21 are basically the same as Figure 1 The transmitting and receiving devices are identically designed, wherein it can be seen in this illustration that the gateway 24 is provided with a multi-core cable 27, via which the release signal can be redundantly relayed to the machine control (not shown). In addition to the multi-core cable 27 for redundant transmission of the release signal, further lines are preferably provided between the gateway 24 and the machine control, for example for transmitting additional information to the machine control, such as, for example, chuck open, no pallet present, pallet in place, pallet clamped, pallet clamped with 10 kN.

[0085] according to Figure 2 Monitoring devices and Figure 1 The difference compared to the monitoring device lies in the fact that Figure 1 The monitoring device comprises only two DMS sensors for determining the clamping force, which are arranged on a single chuck 41. The two DMS sensors are arranged on the chuck 41 in such a way that they detect measured values ​​that are positively correlated with each other. For this purpose, the two DMS sensors are fitted in the upper region of the chuck 41 so that they can reliably and accurately detect the elastic deformation of the material, i.e., the material of the chuck 41, when the workpiece carrier 45 is clamped. The correct clamping of the workpiece 45 in the clamping device 40 can therefore be reliably and safely monitored by the two DMS sensors.

[0086] The two DMS sensors described above are generally sufficient to monitor the secure clamping of the workpiece carrier 45 on the chuck 41, as a predefined elastic deformation of the chuck 41 occurs only when a sufficiently large clamping force is applied to the clamping sleeve 46. However, if a predefined clamping force is applied to the clamping sleeve 46, it can be reliably assumed that the workpiece carrier 45 is securely clamped. If the workpiece carrier 45 is not clamped or incorrectly clamped, this can be detected by the two DMS sensors, as the elastic deformation of the chuck 41 is less when the workpiece carrier 45 is incorrectly clamped than when it is correctly clamped. The measured values ​​that signal correct clamping can be determined and stored through test measurements and calibration of the system. The measured values ​​of the DMS sensors are preferably checked for plausibility by cross-comparison in the transmitter 14. If the measured values ​​appear plausible, they are transmitted to the receiver 21 via the transmitter 14. If the measured values ​​appear implausible, an error message is transmitted. In addition to error messages, the measured values ​​can also be transmitted, if desired. The error message is received by the receiving device 21 and a signal having the value 0 is accordingly present at the two outputs of the gateway 24, which is detected by the machine control. When the release signal assumes the value 0, any ongoing machining operation is interrupted or even cannot be started.

[0087] If the measured values ​​appear plausible, they are transmitted via the transmitting device 14 to the receiving device 21, where they are evaluated by two microprocessor units 25, 26. The measured values ​​are compared with a specified value—the setpoint value. If both microprocessor units 25, 26 detect that the setpoint value has been reached, correct clamping is detected, and a release signal assumes the value 1. This release signal is sent redundantly to the machine control, preferably via a separate line. When the release signal assumes the value 1, the machining operation can be started or continued.

[0088] On the other hand, if at least one of the two microprocessor units of receiving device 21 detects that the setpoint value has not been reached, incorrect clamping is detected and the release signal assumes the value 0, which is again detected by the machine control. In this case, the release signal is also redundantly sent to the machine control. As soon as the release signal assumes the value 0, any ongoing machining operation is interrupted or even prevented from starting.

[0089] In summary, it can be said that correct clamping is only detected when the measured values ​​are both plausible and reach the setpoint value. In all cases, the release signal only takes the value 1 when correspondingly high or predetermined measured values ​​are present at both sensors, which deviate from each other by no more than the predetermined value. Regardless of the physical embodiment of the line / cable, the important thing is that the release signal is transmitted redundantly.

[0090] In addition to the correct clamping of the workpiece carrier 45, the other state of the clamping device 40 or the chuck 41 can be determined by other sensors. By the third sensor 43, on the one hand, it is possible to detect whether the workpiece carrier 45 is installed on the chuck 41. The position of the workpiece carrier 45 relative to the chuck 41 can also be determined by the size of the measurement signal of the third sensor 43, as explained above. By the fourth sensor, it is possible to determine the position of the actuating piston for actuating the clamping element-clamping ball. In particular, it is possible to determine whether the actuating piston is in the initial position or the locked position. In the locked position, the clamping element is pushed radially inward so that the clamping element abuts or can abut against the clamping sleeve with friction locking. If the actuating piston is pushed into the initial position, the clamping element is in the open position or they can at least be pushed back to the open position. Therefore, in the open position, the clamping sleeve 46 of the workpiece carrier 45 can be introduced into the positioning hole 42 of the chuck 41 or removed therefrom. Detecting the corresponding position of the actuating piston is particularly important for automated assembly of the clamping device 40 using a handling robot, as this allows inferences to be drawn as to whether the workpiece carrier 45 can be fed or removed without damaging the clamping device 40. Finally, the position of the clamping device 40 can be determined using a fourth sensor designed as an acceleration sensor. If desired, the clamping device 40 can also be monitored for shake / vibration during workpiece processing using this fourth sensor.

[0091] The measurement data of the various sensors can be redundantly transmitted in the above-described manner via the transmission device 14 to the receiving device 21. It goes without saying that five sensors do not necessarily have to be present, or that when five sensors are present, not all measured values ​​have to be transmitted, or at least not all measured values ​​have to be transmitted all the time, to the receiving device 21. In order to detect the secure clamping of the workpiece carrier, it is generally sufficient to evaluate the data of two DMS sensors.

[0092] Figure 3a Shown throughout according to Figure 2 A cross-sectional view of the chuck 41 of the clamping device is shown with the workpiece carrier 45 shown as being raised. In this illustration, the actuating piston 65 arranged inside the chuck 41 can be seen, which serves to actuate a spherically shaped clamping element 66, by means of which the clamping sleeve 46 fastened to the workpiece carrier 45 can be clamped in the chuck 41. The actuating piston 65, which can be displaced in the Z direction between the illustrated initial position and a locking position, is loaded in the direction of the locking position, i.e., in the direction of the chuck base, by a compression spring.

[0093] In this example, in addition to two inductive sensors 43, 44 arranged on the upper side of the chuck 41 and two DMS sensors 69, 70 arranged on the upper housing portion of the chuck 41, the monitoring device also includes two sensors 71, 72 arranged inside the chuck 41 and operating in a contactless manner, which can detect at least two positions of the actuating piston 65. The two sensors 71, 72 are diametrically opposed to each other and measure the distance to the actuating piston 65. Preferably, inductively operating sensors 71, 72 are used, which can detect at least two, preferably three, different positions of the actuating piston 65. The presence or installation of the workpiece carrier 45 can be detected by the two inductive sensors 43, 44 arranged on the upper side of the chuck 41, while the two DMS sensors 69, 79 measure the elastic deformation of the chuck housing, thereby drawing conclusions about the actual clamping force. The sensors 71, 72 arranged inside the chuck 41 are fixedly fitted and measure the distance to the upper side of the displaceable actuating piston 65. Since there is a large distance Y1 between the lower side of the workpiece carrier 45 and the two inductive sensors 43 and 44 arranged on the upper side of the chuck 41 when the workpiece carrier 45 rises, the two inductive sensors 43 and 44 detect that the workpiece carrier 45 is not installed.

[0094] In order to shift the actuating piston 65 to Figure 3a In the initial position shown, it pneumatically moves upward against the force of the compression spring. To this end, a corresponding overpressure is applied to the annular space below the actuating piston 65. In this initial position, the actuating piston 65 abuts against an upper stop formed by the upper portion of the housing. Consequently, the chuck 41 is in an open position, in which the clamping sleeve 46 of the workpiece carrier 45 can be inserted into or removed from the chuck 41. In the initial / open position of the actuating piston 65, the distance X1 between the actuating piston 65 and the corresponding sensors 71, 72 is at least 100 mm and can be, for example, between approximately 0.5 and several millimeters. In this state, the measured values ​​at the corresponding sensors 71, 72 are detected during calibration and stored as "open position." A measured value is also stored at the two DMS sensors as "open position." Finally, a measured value is stored at the two inductive sensors 43, 44 arranged on the upper side of the chuck 41 as "not installed" or "not present."

[0095] Figure 3b The cross section shows the workpiece carrier 45 clamped thereon. Figure 3aThe chuck 41 is positioned in this position. The actuating piston 65 is displaced downwards in the direction of the chuck base under the force of the compression spring, with no overpressure in the annular space 68. As the actuating piston 65 moves downwards, it presses the clamping ball 66 inwards into the central opening 68 of the chuck 41 via its downwardly widening, slightly conical pressure surface arranged on the inside until it abuts against the shoulder of the clamping sleeve 46. The movement path of the actuating piston 65 in the direction of the chuck base is therefore limited by the clamping ball 66 abutting against the pressure surface of the clamping sleeve 46. The actuating piston 65 is held in the illustrated locking position by the force of the spring, while the clamping sleeve 46 is held by self-retention.

[0096] exist Figure 3b In the locked position of the actuating piston 65 shown in , the distance X2 between the actuating piston 65 and the corresponding sensors 71, 72 is much larger than in the initial position, for example, about 1 to 4 mm. In this state, the measured values ​​present at the corresponding sensors 71, 72 are detected again during calibration and stored as "correct clamping". When the workpiece carrier 45 is clamped, the clamping force exerted by the clamping ball 66 on the clamping sleeve 46 causes an elastic deformation of the chuck housing, which can be repeatedly and accurately measured by the two DMS sensors. Finally, the measured value appears at the two inductive sensors 43, 44 arranged on the upper side of the chuck 41. This measured value is stored as "present" or "installed" of the workpiece carrier because the distance Y2 between the lower side of the workpiece carrier 45 and the two inductive sensors 43, 44 arranged on the upper side of the chuck 41 is relatively small.

[0097] Figure 3c Then, the process of passing through the workpiece carrier without the workpiece carrier is shown. Figure 3a Cross-sectional view of the chuck 41. Since no clamping sleeve is accommodated in the central bore 68 of the chuck 41, the clamping ball 66 can be pushed inwards into the central bore 42 of the chuck 41 by the actuating piston 65, allowing the actuating piston 65 to move completely downwards to its end position under the action of the compression spring 67. This presupposes that the space 68 below the actuating piston 65 is not pneumatically acted upon with a predefined overpressure. In this state, a relatively large distance X3 exists between the actuating piston 65 and the respective sensor 71, 72—for example, approximately 1 to 4 millimeters greater than in the locked position. In this state, the measured values ​​present at the respective sensors 71, 72 are again detected during calibration and stored as "incorrectly clamped" or "workpiece carrier not present."

[0098] The values ​​measured by sensors 71, 72 can be assigned to the three described chuck states, allowing for reliably and repeatedly detecting the respective chuck states. To this end, the two sensors 71, 72 are preferably calibrated for the three states of the chuck 41, which are deliberately and precisely generated. In the respective states of the chuck 41, the two sensors 71, 72 must measure at least approximately the same values ​​or calibration values ​​in order to make an unambiguous assignment of the chuck states. The measurement data of the two sensors are preferably processed independently of one another by two microprocessor units in the manner described above, and their plausibility is checked by cross-comparison of the measurement data, thereby making it possible to make an unambiguous assignment of the chuck states.

[0099] If appropriate, the measured values ​​present at the two sensors 71, 72 do not have to be identical, for example when the two sensors 71, 72 measure at different points on the actuating piston 65, but the measured values ​​must correspond to those measured in the calibration state. In any case, the sensors 71, 72 can also be arranged at different distances from the actuating piston 65. It is only important that at least two, preferably three, operating states of the chuck 41 can be assigned unambiguous values ​​by the two sensors 71, 72 and that these operating states can be clearly distinguished. The three operating states to be distinguished are as follows:

[0100] -chuck open,

[0101] - the chuck is closed and the workpiece carrier is properly clamped,

[0102] - The chuck is closed, there is no workpiece carrier or the clamping sleeve is not present.

[0103] However, fixed individual values ​​are not assigned to the respective operating states, but rather to predefined tolerance windows.

[0104] It will be appreciated that a single chuck and a clamping device with different combinations of the aforementioned sensors can be provided. In the simplest case, only two sensors must be provided, the measured values ​​of which are positively correlated with each other. That is, it is sufficient to provide two DMS sensors to determine the elastic deformation of the chuck housing or to provide two sensors to monitor the position of the actuating piston 65 so that clear conclusions can be drawn about the clamping state / operating state of the chuck. Combinations of the aforementioned sensors are of course also possible, wherein an inductive sensor arranged on the upper side of the chuck can also be provided, which provides information about the position of the workpiece carrier.

[0105] However, in operation of the chuck, the release signal "chuck open" or "chuck closed and workpiece carrier correctly clamped" is only generated when the measured values ​​of both sensors are within a predefined window.

[0106] Instead of the initially described DMS sensors, two sensors for monitoring the position of the actuating pistons can be provided to monitor safe operation of the chuck. However, if desired, a combination of two DMS sensors and two sensors for monitoring the position of the actuating pistons is also possible. If desired, two inductive sensors arranged on the upper side of the chuck can also be combined with these.

[0107] Figure 4 Another clamping device 49 is shown in a perspective view. The clamping device, together with a monitoring device (not shown), once again forms a clamping system. The clamping device 49 is a vise 50 known per se, which is provided with two displaceable clamping jaws 51, 52, one of which 51 is raised in this illustration. The two clamping jaws 51, 52 are actuated by a spindle 60. A workpiece 64, schematically indicated, can be clamped between the two clamping jaws 51, 52. The two clamping jaws 51, 52 can each be fixed to a guide block 53, 54 by screws. In order to secure the workpiece in the vise 50, the workpiece is clamped between the two clamping jaws 51, 52. The vise 50 has a stable base 55, on which two parallel guide rails 56, 57 are provided towards the top for guiding the two displaceable guide blocks 53, 54. For its part, the vise 50 is provided with a clamping sleeve 63 fastened to the underside of the base body 55, by means of which it can be fastened to a chuck, e.g. Figure 2 It goes without saying that the vise 50 can also be fastened to the processing machine in different ways.

[0108] The clamping device 49 is provided with a transmitter (not shown), as already explained. In order to monitor the clamping quality of the workpiece clamped between the clamping jaws 51, 52, a DMS is arranged on each of the two guide rails 56, 57, of which only one DMS 61 is shown in this illustration. To protect the DMS from external influences, a cover cap 62 is provided. The respective DMS is positioned at a point on the guide rails 56, 57 at which high forces and correspondingly high elastic material deformations occur during clamping of the workpiece, which can be measured by the DMS sensor. Due to the fact that the DMS sensors are arranged on the guide rails 56, 57, the clamping force can be measured using these sensors regardless of the clamping jaws used, so that the clamping jaws 51, 52 can be replaced without having to replace anything on the DMS sensor.

[0109] The corresponding guide blocks 53, 54 are also provided with corresponding sensors 58, 59 for detecting the position of the clamped workpiece. The corresponding sensors 58, 59 are arranged in the outer area of ​​the guide blocks 53, 54 so that they are measured at right angles to the upward displacement direction of the clamping jaws 51, 52 (i.e. in the Z direction), so that the distance between the lower side of the clamped workpiece and the corresponding guide blocks 53, 54 can be detected. The two sensors 58, 59 are diagonally opposite to each other. The sensors 58, 59 for position detection are preferably inductive operating sensors in the form of inductive proximity switches. In this way, it is intended to be able to detect, for example, workpieces that are clamped at an angle. Due to the fact that the position detection sensors 58, 59 are arranged on the guide blocks 53, 54, measurements can be performed with these sensors regardless of the clamping jaws used.

[0110] The four sensors mentioned above then form part of the monitoring device in addition to the transmitting device and the receiving device. The transmitting device is preferably accommodated in a recess arranged in the lower half region of the vise. The transmitting device and the receiving device are connected to Figure 1 The transmitting device and the receiving device in the vise 50 are constructed essentially identically and will therefore not be treated in more detail at this point. Since the two position detection sensors 58, 59 are arranged on the movable part of the vise 50 - the guide block, the position detection sensor is connected to the transmitting device accommodated in the base body 55 via a movable cable. The two DMS sensors are connected to the transmitting device via a conventional cable. The transmitting devices can again check the rationality of each other by cross-comparison of the measurement data present at the two DMS sensors. Therefore, by means of the two DMS sensors, the clamping quality of the clamped workpiece can be redundantly monitored in the manner described previously. In addition to the four sensors mentioned above, further sensors can also be provided, such as, for example, acceleration sensors arranged on the vise, by means of which the position of the vise and the movement of the vise can be detected as required. In addition, a sensor for measuring the distance between the two guide blocks 53, 54, for example, can also be provided.

[0111] It goes without saying that the above examples of embodiments should not be considered conclusive or comprehensive. Thus, for example, both the transmitting device and the receiving device can be provided with two independent transmitters and receivers, each for redundant transmission of measured values. To monitor other parameters, additional sensors can also be provided on the chuck or the corresponding clamping device. For example, a temperature sensor can also be used. Data from other sensors can also be transmitted wirelessly via the transmitting device. Instead of sensors 71, 72 operating based on induction, ultrasonic sensors, capacitive or optical sensors can also be provided to determine the position of the actuating piston.

[0112] On the other hand, simpler variants of the monitoring device according to the invention are also entirely conceivable, in which, for example, the clamping force is redundantly monitored using only two sensors. The clamping force does not necessarily need to be absolute and detected with high resolution, but, depending on the specific situation, it may be sufficient to detect and / or monitor the clamping force in steps, for example, from two to ten steps, and transmit the clamping force via the transmitting device. Bidirectional data exchange between the transmitting and receiving devices is also possible. Thus, for example, software updates can be sent from the receiving device to the transmitting device.

[0113] The term “clamping quality” is understood herein as the ratio between the required clamping force (depending on the dimensions of the component and the processing forces acting on the workpiece during its processing) and the actually measured clamping force or existing measurement value.

[0114] Several advantages of the monitoring device designed according to the present invention are briefly described as follows:

[0115] - The clamping quality between the workpiece carrier / workpiece and the clamping device can be reliably monitored and wirelessly transmitted to a remote point;

[0116] - The data sent can be detected, stored and evaluated externally;

[0117] -Reliable and safe monitoring of the clamping quality of the clamped workpiece carrier or the clamped workpiece using only two sensors;

[0118] - Parameters can be continuously monitored;

[0119] The measurement of specific parameters increases process reliability, wherein in particular the continuous monitoring of the clamping force or the pull-in force of the clamping sleeve provides meaningful and safety-related data;

[0120] - By providing two different microprocessors in the transmitting and receiving device, independent and redundant preparation of the measurement data can be ensured;

[0121] The entire measurement chain, including the transmission and evaluation of the measurement data, is designed to be reliable and redundant.

[0122] Reference Signs List

[0123] 1. Machine space 36. Third sensor module

[0124] 2. Clamping system 37. Fourth sensor module

[0125] 3. Clamping device

[0126] 5. Base plate 40. Clamping device

[0127] 6. First chuck 41. chuck

[0128] 7. Second chuck 42. Center hole

[0129] 8. Third chuck 43. Sensor presence tray

[0130] 9. Fourth chuck

[0131] 45. Workpiece bracket (pallet)

[0132] 46. ​​Clamping sleeve

[0133] 12. Monitoring device

[0134] 14. Launching device 49. Clamping device

[0135] 15. First microprocessor unit 50. Vise

[0136] 16. Second microprocessor unit 51. Gripper

[0137] 17. Transmitting antenna 52. Gripper

[0138] 18. Acceleration sensor 53. Guide block

[0139] 19. Feed 54. Guide block

[0140] 55. Matrix

[0141] 21. Receiving device 56. Guide rail

[0142] 22. Receiving antenna 57. Guide rail

[0143] 23. First cable 58. First position sensor

[0144] 24. Gateway 59. Second location sensor

[0145] 25. First microprocessor unit 60. Spindle 26. Second microprocessor unit 61. DMS

[0146] 27. Second cable 62. Cover

[0147] 28. Machine control device 63. Clamping sleeve

[0148] 29. Third cable 64. Workpiece

[0149] 30. Manipulating robots 65. Actuating pistons

[0150] 31. Fourth cable 66. Clamping ball

[0151] 32. Repair tools 67. Compression spring

[0152] 68. Ring Space

[0153] 34. First sensor module 69. First DMS sensor 35. Second sensor module 70. Second DMS sensor

[0154] 71. First inductive sensor (actuating piston)

[0155] 72. Second inductive sensor (actuating piston)

[0156] L1-L4 lines (sensor module)

[0157] A1-C4 sensor

Claims

1. A monitoring device for monitoring the clamping quality of a workpiece carrier or a workpiece clamped in a clamping device (3, 40, 49), comprising at least one sensor to be arranged in the clamping device (3, 40, 49) and a transmitting device (14) for wirelessly transmitting parameters determined by the sensor to a receiving device (21), characterized in that The monitoring device (12) comprises at least two sensors (A1-A4) for independently detecting the clamping quality of a clamped workpiece carrier or workpiece, and the transmitting device (14) is configured such that it redundantly transmits the determined or calculated parameter or parameters to the receiving device (21), wherein the monitoring device (12) comprises at least one sensor module (34, 35, 36, 37) by means of which the measured values ​​present at the sensor are digitized and transmitted to the transmitting device (14), wherein the transmitting device (14) is provided with two independent first and second microprocessor units (15, 16) which are configured to be ready in each case for the respective sensor module (34, 35, 36, 37). 5, 36, 37), wherein the transmission device (14) comprises at least one transmitting antenna (17) for transmitting the measurement data prepared by the two independent first and second microprocessor units (15, 16), wherein the monitoring device comprises a receiving antenna (22) for receiving the data transmitted by the transmission device (14) and a gateway (24) connected to the receiving antenna (22), wherein the gateway (24) is provided with two independent third and fourth microprocessor units (25, 26), by means of which the received data are in each case further processed independently and redundantly, and wherein the gateway (24) is connected to a machine control (28) of a processing machine.

2. The monitoring device according to claim 1, characterized in that At least two sensors (A1-A4) are arranged such that their measured values ​​are positively correlated with each other.

3. The monitoring device according to claim 1, characterized in that At least two sensors (A1-A4) are designed and arranged such that elastic deformation of the material of the chuck (6, 7, 8, 9, 41) or the vise (50) of the clamping device (3, 40, 49) can be measured during clamping of the workpiece carrier or the workpiece, wherein the sensors are strain gauge sensors (DMS).

4. The monitoring device according to claim 1, wherein: The clamping device comprises at least one chuck (41) having an actuating piston (65) arranged therein and displaceable in the Z direction for actuating a clamping element (66) for clamping a clamping sleeve (46), characterized in that the monitoring device comprises at least two sensors (71, 72) operating in a contactless manner, by means of which at least two positions of the actuating piston (65) can be detected independently of each other.

5. The monitoring device according to claim 4, characterized in that The sensors are inductive operating sensors (71, 72) by means of which at least one open position and one locked position of the actuating piston (65) can be detected.

6. The monitoring device according to any one of claims 1 to 5, for monitoring the clamping quality of a workpiece carrier clamped by the clamping device (3, 40), characterized in that The monitoring device comprises at least one further sensor (B1-B4, 43), by means of which the mounting of the workpiece carrier on the clamping device (3, 40) can be detected.

7. The monitoring device according to any one of claims 1 to 5, for monitoring the clamping quality of a workpiece clamped in a vise (50) of a clamping device (49), wherein: The vise (50) is provided with two guide blocks (53, 54), wherein a clamping jaw (51, 52) for clamping a workpiece is fastened to each guide block (53, 54), characterized in that the monitoring device comprises at least two further sensors (58, 59) by means of which the mounting of the workpiece on the corresponding guide block (53, 54) of the vise (50) can be detected.

8. The monitoring device according to any one of claims 1 to 5, characterized in that: The monitoring device is provided with further sensors (C1-C4), by means of which the position of the element for activating the clamping element can be detected.

9. The monitoring device according to claim 1, characterized in that The gateway (24) processes the measured values ​​sent by the sending device (14) so ​​that when it is determined that the detected measured values ​​are consistent and reach the predetermined measured values ​​of the machine control device, a redundant signal is output to the machine control device (28) for a correctly clamped workpiece carrier or a correctly clamped workpiece and / or for reliable operation of the machine tool.

10. A clamping system (2) comprising a clamping device (3, 40, 49) for clamping a workpiece carrier or a workpiece and a monitoring device according to any one of claims 1 to 9, characterized in that The monitoring device (12) is provided with at least two sensors (A1-A4), which are arranged in the clamping device for independently detecting the clamping force acting on the clamped workpiece carrier or the clamped workpiece.

11. The clamping system (2) according to claim 10, characterized in that The transmitting device (14) of the monitoring device (12) comprises a radio transmitter arranged on the clamping device (3, 40, 49), and the receiving device (21) comprises a radio receiver arranged remote from the clamping device, wherein the transmitting device (14) comprises two independent first and second microprocessor units (15, 16) configured to prepare the measured values ​​sent independently and redundantly by the corresponding sensor modules (34, 35, 36, 37) and to check their plausibility by cross-comparison of the measured data.

12. The clamping system (2) according to claim 11, characterized in that The sensors (A1-A4) are strain gauge sensors that are frictionally locked and / or securely bonded to the chuck or vise of the clamping device (3, 40, 49) so that their signals are substantially proportional to the clamping force.

13. The clamping system (2) according to any one of claims 10 to 12, characterized in that The clamping device (3, 40) comprises at least one chuck (6, 7, 8, 9, 41) for clamping a workpiece carrier, and is characterized in that the chuck (6, 7, 8, 9, 41) comprises a sensor (B1-B4, 43) arranged in an upper area for detecting the installation of the workpiece carrier.

14. The clamping system (2) according to claim 10 , comprising a chuck ( 41 ) for clamping a workpiece carrier ( 45 ), the workpiece carrier ( 45 ) being provided with a clamping sleeve ( 46 ), wherein the chuck ( 41 ) is provided with an actuating piston which can be displaced between an initial position and a locking position for actuating a clamping element for clamping the clamping sleeve ( 46 ), characterized in that The chuck (41) is provided with another sensor for monitoring the position of the actuating piston, in particular, the chuck (41) is provided with at least two sensors (71, 72) operating in a non-contact manner, by means of which at least two positions of the actuating piston (65) can be detected independently of each other.

15. The clamping system (2) according to claim 10 , comprising at least two chucks (6, 7, 8, 9) for clamping a workpiece carrier, the workpiece carrier being provided with a number of clamping sleeves corresponding to the number of chucks, wherein: Each chuck (6, 7, 8, 9) is provided with an actuating piston which can be shifted between an initial position and a locking position for actuating a clamping element for clamping a corresponding clamping sleeve, characterized in that at least one chuck is provided with an additional sensor (C1-C4) for monitoring the position of the actuating piston, in particular in that at least one chuck (41) is provided with at least two sensors (71, 72) operating in a contactless manner, by means of which at least two positions of the actuating piston (65) can be detected independently of each other.

16. Clamping system (2) according to any one of claims 10 to 12, characterized in that The clamping device is designed as a vise (50) with two clamping jaws (51, 52), wherein a sensor for determining the clamping force of a clamped workpiece is assigned to each clamping jaw (51, 52).

17. A method for monitoring the clamping device of a processing machine by means of a monitoring device according to any one of claims 1 to 9, characterized in that The clamping quality of a workpiece carrier or a workpiece clamped in the clamping device is determined by at least two independent sensors (A1-A4), in that the measurement data determined by the corresponding sensors (A1-A4) are compared with each other and checked for plausibility, and in that one or more parameters determined or calculated are redundantly sent by the sending device (14) to the receiving device (21) and sent by the gateway (24) to the control device (28) of the processing machine.

18. The method according to claim 17, characterized in that The plausibility check includes checking the consistency of parameters determined after parameter preparation by two independent first and second microprocessor units (15, 16) of the transmitting device (14) and compared with one another.

19. The method according to claim 18, characterized in that The determined or calculated parameter or parameters are redundantly transmitted in the form of data packets to the receiving device (21) via the transmitting device (14), and the sent data are checked on the receiver side for plausibility.

20. The method according to claim 19, wherein The receiving device (21) comprises a gateway (24), characterized in that, when the parameters determined and compared with one another agree and reach predetermined measured values, a release signal for safe operation is generated by the gateway (24) and redundantly transmitted to the control device (28) of the processing machine.

21. The method according to claim 20, characterized in that The gateway (24) sends the release signal in the form of a binary signal, wherein the release signal takes the value 1 when the detected measurement value is reasonable and reaches a predetermined value, and wherein the release signal takes the value 0 when the detected measurement value is unreasonable or does not reach the predetermined value.

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