Safety device for a beam processing device and process

Abstract

Safety device (20) for a beam processing device (10), in particular a laser beam welding device, in which a beam tool (12; 12A) can emit at least one high-energy beam (S) from a beam source (16), in particular a laser beam, onto a workpiece (W) and the beam tool is movable and positionable by a manipulator (14), comprising: a first detection device (30) which is assigned to the manipulator (14) in such a way that a position of the beam tool (12; 12A) can be determined, a second detection device (32) and at least one third detection device (34) which is independent of the second detection device, wherein the second and third detection devices (32, 34) are each assigned to the beam tool (12; 12A) or the workpiece (W) such that an emission direction of the beam (S) and / or a position (B) of the beam on the workpiece (W) can be determined, and an evaluation device (22) that evaluates signals (24, 26, 28) from the at least three detection devices (30, 32, 34) to monitor the process-compliant alignment of the beam (S) and generates a corresponding output signal (36), wherein the output signal (36) causes the beam source (16) to be enabled or disabled.

Description

[0001] The invention relates to a safety device for a beam processing device, in particular a laser beam welding system, and a method for beam processing, in particular for laser beam welding.

[0002] In high-volume production, beam processing methods are increasingly used, in which a beam tool emitting a beam from a beam source is moved and positioned by a manipulator in one or more axes. In semi- or fully automatic devices, the movement and beam emission are controlled by a central control unit (PLC).

[0003] To protect people near the equipment, such as operators or maintenance personnel, extensive safety measures must be implemented. In the case of laser processing equipment, people, and especially their eyes, must be protected from the high-energy laser radiation.

[0004] To avoid hazards from a misdirected or misaligned beam, it is known, for example in laser processing processes, to design the beam processing device as a laser cell with a complete protective enclosure or at least to partially demarcate or surround it with laser safety walls.

[0005] The protective enclosure or laser safety barriers are designed to withstand an incoming beam, at least for a short time, to prevent uncontrolled emission of laser radiation (passive barriers). Active barriers are also used, which not only prevent the laser beam from penetrating but also detect the impact of radiation and shut off the laser.

[0006] A disadvantage is that protective enclosures incur high investment costs and make the processing process complex and inflexible. The components to be processed must be introduced into the laser cell through a sophisticated gate system, which increases cycle time.

[0007] Furthermore, safety devices are known that aim to detect and prevent misalignment of the laser beam.

[0008] German patent application DE 20 2005 007 140 U1 proposes a safety device to supplement the safety barrier for a fully automatic laser welding system. This device has one or more sensors that can be assigned to the workpiece or beam tool and can enable or disable beam emission. The proposed safety device monitors the correct alignment of the beam tool with the workpiece and is therefore unsuitable for welding devices where the beam emission direction and the alignment of the beam tool do not necessarily coincide, such as with scanner optics.

[0009] German patent application DE 101 63 392 A1 discloses a safety shutdown for a motion-controlled laser tool, which is activated in the event of an impermissible tilt of the tool and shuts down the tool or the process. The tilt of the tool is detected by means of an inclination sensor mounted on the tool. This safety shutdown considers only the orientation of the tool in space. Misalignment of the tool relative to the workpiece is disregarded by the safety circuit as long as the tool exhibits a process-compliant tilt.

[0010] A safety system for a laser processing device is known from DE 10 2008 052 579 A1. The system aims to monitor the movement of a device (e.g., a laser focusing head) by means of at least one camera attached to the device.

[0011] German patent application DE 10 2009 014 559 A1 discloses a laser welding device with an integrated safety concept. The system aims to increase safety by combining a laser welding head with a robot.

[0012] An optoelectronic monitoring device for safeguarding a source of danger arranged on a movable machine part is known from DE 20 2007 010 884 U1.

[0013] The object of the invention is to provide a safety device for a beam processing device that functions reliably and in which the disadvantages described above do not occur.

[0014] Another task is to improve the integrability of a beam processing device or processing process equipped with the safety device into existing production lines or processes.

[0015] This problem is solved with regard to the safety device by the features of claim 1, with regard to the beam processing device by the features of claim 8 and with regard to the method by the measures of claim 12.

[0016] Further advantageous embodiments of the invention are set out in the dependent claims.

[0017] A safety device for a beam processing device is specified, in which a beam tool can emit at least one high-energy beam from a beam source in an emission direction onto a workpiece, and the beam tool can be moved and positioned by a manipulator within a working space.

[0018] Preferably, this is a laser beam welding device and the beam source is a laser source. Alternatively, other types of high-energy beams, such as electron beams, can be used and / or other processing operations can be performed, e.g., separating, cutting, etc.

[0019] A beam generated by the beam source is guided via suitable beam guidance devices into a beam tool, focused, and emitted by the beam tool. The beam tool can be, for example, a welding head with a fixed emission direction, or a scanner optic can be used, which allows the emission direction of the beam to be additionally changed and is therefore largely independent of the orientation of the beam tool.

[0020] The blasting tool is held by a manipulator. The manipulator can have one or more movable linear and / or rotational axes; in particular, the manipulator is a multi-axis articulated robot arm.

[0021] The invention is based on the consideration that by evaluating at least three detection signals, one of which relates to the position of the beam tool and two of which relate to the position or direction of the beam, the orientation and position of the beam in space can be reliably checked and deviations, whether due to incorrect positioning of the manipulator or the tool, can be reliably detected.

[0022] The proposed safety device includes a first detection device assigned to the manipulator such that the position of the beam tool can be determined. Furthermore, the safety device comprises a second detection device and at least one third detection device independent of the second, each assigned to the beam tool or the workpiece such that the emission direction of the beam and / or the position of the beam on the workpiece (processing point) can be determined. The safety device also includes an evaluation device that evaluates signals from the at least three detection devices to monitor the correct alignment of the beam during the process and generates a corresponding output signal, which enables or disables the beam source.

[0023] In addition to the manipulator's current position, the safety device detects at least two signals indicating the beam's position. By evaluating these signals together, the beam's alignment with the workpiece can be checked at any given time, thus ensuring the necessary safety. This safety device is particularly suitable for laser welding systems where the laser beam can be deflected relative to the welding tool using a scanner optic.

[0024] In one embodiment, the emission direction of the beam can be determined using the signal from the second detection device, and the position of the beam on the workpiece can be determined using the signal from the third detection device. This enables a plausibility check of the signals against each other. Thus, the position of the beam can be determined using any two of the three signals and verified using the third signal.

[0025] The evaluation device analyzes the signals from at least three detection devices to verify the laser beam's alignment within the process. The evaluation is performed according to a predefined logic. For example, it can check whether the detection signals deviate from stored target signals. Alternatively, the actual spatial position of the beam can be calculated from the signals and compared with stored target data. Other evaluation methods are possible. Preferably, the evaluation device is implemented as a processing unit, and the evaluation is performed by suitable software. Depending on the evaluation, an output signal is generated that either blocks or enables the beam source.

[0026] To increase safety, the safety device is preferably real-time capable, i.e., the evaluation and signal transmission takes place in real time, in particular with a reaction time of less than 10 microseconds.

[0027] The safety device ensures that only a correctly aligned beam is emitted. Preferably, the safety device is designed such that the beam source is blocked and only released by a releasing output signal.

[0028] Preferably, the output signal directly effects the enabling or disabling, e.g., as a switching signal within the circuit of the beam source. Alternatively, the output signal of the evaluation device can first be further processed, e.g., in the central control unit of the beam processing device.

[0029] For detection, the safety device preferably uses at least one detection element in the form of a sensor in each detection device. A wide variety of sensors and sensor systems can be used, e.g., tactile sensors, optical sensors, light barriers, gravimetric sensors, thermal sensors, etc. A detection device can contain two or more identical or different detection elements.

[0030] The first detection device associated with the manipulator serves to determine the position of the end effector or welding tool. For this purpose, the first detection device can, for example, have several sensors for determining the axis positions. The first detection device can, for instance, already be integrated into the manipulator. For example, so-called safe robots are known that have their own safety module, which is configured to monitor the axis position of the manipulator and detects and prevents unauthorized movement of the robot. The safety module responsible for monitoring the safety functions is implemented redundantly using safe technology. Preferably, the robot's safety module can be used as the first detection device.

[0031] The second and third detection devices serve to determine the beam's emission direction and its point of impact on the workpiece. For this purpose, they can be located on the blasting tool or on the workpiece, or directed towards it. If the emission direction is predetermined by the orientation of the blasting tool, it suffices to detect the orientation of the blasting tool, e.g., using tilt sensors. If, on the other hand, the beam is movable relative to the tool's orientation, e.g., by a scanner device, the mirror position is preferably detected, e.g., using rotary angle sensors.

[0032] Determining the beam's point of impact on the workpiece is possible, for example, by aligning the detection area with the workpiece, e.g., by aligning an optical detection device or an optical sensor with the workpiece surface.

[0033] To further increase safety and avoid impairment due to failure of a detection means, in one embodiment each detection device is designed as a redundantly operating detection system, wherein preferably two or more detection means operate in parallel in one detection system.

[0034] For individuals in the vicinity of the manipulator, the manipulator's movement can also pose a hazard. Due to the manipulator's rapid movements and changes in direction, separate monitoring is advisable. Therefore, one configuration of the safety device includes a monitoring device that detects personnel entering the manipulator's work area. A monitoring signal provided by the monitoring device is also evaluated by the evaluation device and can, for example, be identified as an impermissible process deviation, causing the evaluation device to generate a blocking output signal.

[0035] The monitoring device can be implemented using known structural barriers that detect and, if necessary, prevent unauthorized access. For example, the monitoring device could be a safety light curtain known from the prior art, arranged around the work area, with a light barrier detecting any interruption of the light curtain. Alternatively, the monitoring device could be implemented using multidimensional laser scanning systems that scan the monitored area. This security solution could utilize conventional projectors and cameras, mounted, for example, on the ceiling.

[0036] If the processing is a laser processing process, the resulting process light and secondary radiation also pose a potential hazard to humans. However, since the intensity of the scattered radiation and process light decreases exponentially with increasing distance from the processing point, the resulting hazard potential also decreases rapidly with increasing distance. To prevent personnel from being endangered by secondary radiation, a safety zone is defined in a particularly preferred embodiment in addition to the manipulator's working area and monitored by the monitoring device with regard to access control. The safety zone is an area around the beam spot on the workpiece within which the secondary radiation from the processing beam exceeds a predefined limit. The size of the safety zone can be fixed or adjusted during the processing process, e.g.,calculated or otherwise determined from radiation parameters and / or measured secondary radiation.

[0037] The beam processing device typically has a central control unit (PLC) that manages the entire processing operation. The evaluation unit can be integrated into this central control unit, particularly if it is a real-time control unit. However, it is especially preferred that the evaluation unit for the safety device be implemented as a separate unit. This decouples the safety monitoring from other control and monitoring processes, further reducing response times and increasing safety.

[0038] The safety device completely and reliably prevents misalignment or misemission of the beam, thus fully replacing the function of an enclosure or laser safety wall. Advantageously, a complete enclosure or spatial separation of the processing device by safety walls can be dispensed with, and the beam processing device is designed as a safety-wall-free beam processing device, in particular as a laser safety-wall-free laser beam welding device.

[0039] If the secondary radiation generated during the processing process is to be shielded, the beam processing device can, in one embodiment, have a spatial boundary that provides protection against secondary radiation generated during the beam processing process, such as a protective curtain against secondary radiation and process light.

[0040] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of exemplary embodiments. Where the term "may" is used in this application, it refers to both the technical possibility and the actual technical implementation.

[0041] The following are examples of implementation explained with reference to the accompanying drawings. These show: Fig. 1 A schematic representation of a beam processing device with a safety device Fig. 2 a schematic representation of a welding head with exemplary detection means Fig. 3 A schematic top view of a blast processing device with working area and safety zone

[0042] Fig. Figure 1 shows a schematic representation of a beam processing device 10 with safety device 20 using the example of a laser beam welding device.

[0043] The laser beam welding device 10 comprises a beam or welding tool 12 with a scanner optic, which is held and positioned by a multi-axis manipulator 14 in the form of an articulated robot arm. Alternatively, the beam tool itself can, of course, also be a welding head with a fixed beam orientation, and other manipulators, e.g., single- or multi-axis linear drives, can be used. Light from a beam source 16 or laser source is coupled into the beam tool 12 via suitable beam guidance devices (not shown) and emitted by it as a beam S onto a workpiece W.

[0044] To control the processing process, the beam processing device 10 further comprises a central control unit 18 for controlling the beam source 16, the beam tool 12 and the robot 14. The central control unit 18 controls the processing parameters and the movement of the beam relative to the workpiece and is coupled to the beam source 16, the beam tool 12 and the robot 14 in a suitable manner (not shown).

[0045] The in Fig. The laser beam welding device 10 shown in Figure 1 further comprises a safety device 20 for monitoring the laser beam positioning. The safety device 20 includes an evaluation device 22, which evaluates signals 24, 26, and 28 from detection devices 30, 32, and 34 to verify whether the beam is aligned correctly for the process. For this purpose, the evaluation device 22 uses suitable logic. The evaluation is preferably software-based, and in particular, the evaluation is performed in real time using secure software.

[0046] The evaluation device 22 generates an output signal 36 that enables or disables the beam source 16. For this purpose, the evaluation device 22 is coupled to the laser source 16 in a suitable manner, preferably in a direct switching connection that takes precedence over the central control unit 18.

[0047] A first detection device 30 is assigned to the robot 14 and has, for example, several sensors with which the axis positions of the robot 14 can be detected. The first detection device 30 is preferably designed as a robot-integrated safety assembly, as used in so-called safe robots, and allows the continuous monitoring of the robot's axis movements. The safety assembly 30 operates independently of the central control unit 18, making the data available in real time with short response times. The safety assembly 30 is typically designed as a redundant system.

[0048] A second and a third detection device 32 and 34 are set up to detect the emission direction of the beam or the position of the beam spot or the processing point B on the workpiece W.

[0049] If a welding head with scanner optics is used as the beam tool 12, the emission direction of the beam S is largely independent of the orientation of the beam tool 12. In this case, a detection device 32 can be used which, for example, detects the tilt angle of the scanner mirrors via rotary angle sensors and thus makes the beam emission direction determinable.

[0050] Furthermore, a blasting or welding tool 12A can also be used in the blast processing device 10, in which the emission direction of the beam S relative to the tool 12A is fixed, schematically shown in Fig. 2 shown. In this case, it may be sufficient to use detection devices that can detect the orientation of the welding head in order to determine the beam direction and beam spot position. For example, as shown in Fig. As indicated in Figure 2, one or more tactile sensors 38 may be used, such as those used in tactile seam tracking systems. Likewise, one or more tilt sensors 40 may be used.

[0051] Optical detection devices, preferably those operating with one or more optical sensors 42 or camera systems, can be used to detect the position of the beam spot on the workpiece. The detection range is preferably matched to the wavelength of the radiation used. Such detection systems are already used in seam tracking systems to detect the orientation of the laser beam relative to the weld line.

[0052] The detection devices mentioned are examples. Of course, a person skilled in the art can select suitable detection devices from the sensors and monitoring systems known in the prior art, such as distance or position sensors. Likewise, more than two detection devices can be provided and used in the safety device to detect the direction of beam emission and the position of the beam spot.

[0053] The signals 24, 26, 28 generated by the detection systems 30, 32, 34 are acquired and evaluated by the evaluation device 22. Fig. Figure 1 shows the evaluation device 22 as a separate component. This enables a particularly short reaction time. Alternatively, when using suitable high-speed systems, the evaluation device 22 can also be integrated into a system-side control device, e.g., the central control device 18 of the beam processing system 10.

[0054] By combining the evaluation of at least three detection signals, the beam alignment can be reliably and safely monitored and ensured.

[0055] The in Fig. The safety device 20 shown also has a monitoring device 44 for monitoring person access to a danger zone 100 surrounding the manipulator 12. Fig. 3 shown hatched.

[0056] The danger zone 100 is determined as follows: Fig.Figure 3 shows a top view, firstly through the working area 110 of the manipulator 14. Secondary radiation is also emitted at the processing point B, meaning that even a person outside the working area 100 could still be at risk. Therefore, the monitoring device 44 additionally incorporates a safety zone 120 that extends around the processing point B. The diameter of this zone 120 is determined by the requirements for the permissible intensity of the secondary radiation and the decrease in radiation intensity with distance from the processing point B. The diameter of the safety zone 120 can be fixed or calculated or otherwise determined from the process data.

[0057] The monitoring device 44 detects a person entering the danger zone 100. This can be done, for example, by means of camera-based monitoring. If a person is detected inside the danger zone 100, the radiation source 12 is blocked. For this purpose, a monitoring signal 46 from the monitoring device 44 is also taken into account by the evaluation device 22 of the safety device 20 and, if necessary, triggers a blocking output signal 36.

[0058] Preferably, the safety device 20 is designed as a redundant system, i.e., both the devices for detecting the quantities to be monitored and the evaluation unit are each designed redundantly.

[0059] The safety device 20 completely prevents unintentional or accidental incorrect or faulty radiation exposure. Consequently, there is no need to enclose the laser welding device or shield it with laser safety walls. This reduces unproductive downtime, such as that caused by opening and closing the enclosure. The laser welding device 10 equipped with the safety device 20 is characterized by a reduced footprint, increased flexibility, and easy accessibility. Furthermore, the welding device can be easily integrated into existing production lines.

[0060] To protect against secondary radiation, a spatial barrier 48, e.g., in the form of a simple protective curtain, can be provided as an alternative or supplement to the described monitoring device 44, to shield against scattered radiation and process light. Alternatively or additionally, the plant operators can wear protective goggles.

[0061] The examples shown are not to scale and are not limiting. Variations within the scope of professional practice are possible. Reference symbol list 10 Beam processing device 12 blasting tools 14 Manipulator 16 Beam source 18 central control unit 20 Safety device 22 Evaluation device 24, 26, 28 signals 30, 32, 34 Detection device 36 Output signal 38 tactile sensors 40 tilt sensor 42 optical sensor 44 Monitoring device 46 Monitoring signal 48 Protective curtain against secondary radiation 100 Danger zone 110 workspace 120 safety zone B Processing point S beam W workpiece

Claims

[1] Safety device (20) for a beam processing device (10), in particular a laser beam welding device, in which a beam tool (12; 12A) can emit at least one high-energy beam (S) from a beam source (16), in particular a laser beam, onto a workpiece (W) and the beam tool is movable and positionable by a manipulator (14), comprising: a first detection device (30) which is assigned to the manipulator (14) in such a way that a position of the beam tool (12; 12A) can be determined, a second detection device (32) and at least one third detection device (34) which is independent of the second detection device, wherein the second and third detection devices (32, 34) are each assigned to the beam tool (12; 12A) or the workpiece (W) such that an emission direction of the beam (S) and / or a position (B) of the beam on the workpiece (W) can be determined, and an evaluation device (22) that evaluates signals (24, 26, 28) from the at least three detection devices (30, 32, 34) to monitor the process-compliant alignment of the beam (S) and generates a corresponding output signal (36), wherein the output signal (36) causes the beam source (16) to be enabled or disabled. [2] Safety device according to claim 1, wherein the emission direction of the beam (S) can be determined by the second detection device (32) and the position of the beam (S) on the workpiece (W) can be determined by the third detection device (34). [3] Safety device according to one of the preceding claims, wherein the safety device is capable of real-time operation. [4] Safety device according to one of the preceding claims, wherein the first detection device (30) is a safety assembly of the manipulator (14) which is configured to monitor the axis positions of the manipulator (14). [5] Safety device according to one of the preceding claims, wherein each detection device (30, 32, 34) is designed as a redundant detection system. [6] Security device according to one of the preceding claims, further comprising a monitoring device (44) that detects the access of persons to a work space (110) of the manipulator (14), wherein a monitoring signal (46) of the monitoring device is evaluated by the evaluation device (22). [7] Safety device according to claim 6, wherein the monitoring device (44) monitors a danger zone (100) which consists of the working space (110) of the manipulator (14) and a safety zone (120) surrounding the processing point (B). [8] Beam processing device (10), in particular laser beam welding device, comprising: a beam tool (12; 12A) which emits at least one high-energy beam (S) from a beam source (16), in particular a laser beam, can be emitted onto a workpiece (W), a manipulator (14) that can move and position the blast tool (12; 12A), and a safety device (20) according to one of the preceding patent claims. [9] Beam processing device (10) according to claim 8, wherein the evaluation device (22) of the safety device (20) is designed as a separate evaluation device. [10] Beam processing device according to claim 8 or 9, which is designed as a shield-free laser beam processing device. [11] Beam processing device according to one of claims 8 to 10, further comprising a spatial boundary (48) surrounding the beam processing device (10) which provides protection against secondary radiation generated during the beam processing process. [12] Method for workpiece processing using a high-energy beam (S), in particular laser beam welding process, with a beam processing device (10) according to one of claims 8 to 11, in which the evaluation unit (22) of the safety device (20) evaluates the signals from the at least three detection devices (24, 26, 28) to check the process-compliant alignment of the beam (S) and generates a corresponding output signal (36) and the output signal (36) causes the beam source (16) to be blocked or enabled. [13] Method according to claim 12, wherein the evaluation and signal transmission takes place in real time. [14] Method according to claim 12 or 13, which is carried out without laser safety barriers. [15] Method according to one of claims 12 to 14, wherein, for generating the output signal (36), a monitoring signal (46) of a monitoring device (44) is further evaluated which detects a person entering a work space (110) or danger space (100) surrounding the manipulator.

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