Protection device, bending machine and bending machine operation method

Abstract

To provide a protection device 51 which ensures a work clearance 14 in plastic processing equipment 1.SOLUTION: A protection device comprises: a light source 52 that supplies a light beam 56 into a work clearance 14; an optical receiver 54 that is disposed facing the light source 52 and receives the light beam 56; a photoelectric switch control part 71 having a safety-oriented configuration that redundantly processes a sensor signal of the optical receiver 54; an adjustment apparatus 28 that is attached to a machine frame or an upper tool 21 of plastic processing equipment 1, provides linear movement for the light source 52 and the optical receiver 54, and comprises drive parts 26 and 27, a stroke sensor, and a stroke measurement system 58, 59, and 60 having a management part for the stroke sensor and configured in a safety-oriented manner; and an adjustment control part 83 that is connected to the adjustment apparatus 28, is configured in a safety-oriented manner, evaluates the sensor signal of the stroke sensor and a signal of the management part, and controls and drives the drive parts 26 and 27.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a protection device, a bending machine and a method for operating a bending machine. [Background technology]

[0002] Patent document 1 discloses a protection device for machines such as squaring presses, shears, punches, etc., in which a first machine part performs a processing movement relative to a second machine part, between which a first optical isolator, in particular a laser photoelectric switch, whose light beam runs perpendicular to the direction of the processing movement, is arranged with respect to one of the machine parts, such that its light beam has a safe distance from the first machine part, and a stop device is arranged which stops the processing movement when its light beam is interrupted, and a switch-off device switches off the stop device just before its light beam is interrupted by the other machine part. A second photoelectric switch, which serves to adjust the safe distance, is attached to the safety device, which is arranged together with the first photoelectric switch on one of the machine parts in a manner that is adjustable in the direction of the processing movement, and the light beam of the second photoelectric switch runs between the light beam of the first photoelectric switch and the first machine part parallel to the light beam, and the distance between the two beams approximately corresponds to the safe distance.

[0003] The patent document 2 describes a protection device for machines such as squaring presses, shears, punches or the like, in which a first machine part performs a processing movement relative to a second machine part, in which at least one photoelectric switch can be positioned relative to one of the machine parts between which the light beam is adjustable by a safety device equipped with the photoelectric switch, and in which a stopping device stops the processing movement when the light beam is interrupted. Furthermore, means are provided for performing a first movement of the safety device until the light beam is interrupted by the machine part equipped with the safety device and for performing a second movement of the safety device in the opposite direction, the stroke of the second movement defining the safe distance can be predefined by an electrical measuring and / or control device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DE 19717299 [Patent Document 2] DE 10123562 A1 Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a protection device, a bending machine and a method for operating a bending machine, which make it possible to achieve an improved level of safety. [Means for solving the problem]

[0006] In a first aspect of the invention, the problem is solved by a protection device for securing a working gap of a plastic processing machine, which comprises a light source arranged to provide a light beam into the working gap, a light receiver arranged opposite the light source and arranged to receive the light of the light source, a photoelectric switch control arranged in a safety-oriented form for redundantly processing a sensor signal of the light receiver, and an adjustment device attached to the machine frame or to the upper tool of the plastic processing machine and arranged to provide a linear movement with respect to the light source and the light receiver, the adjustment device comprising a stroke measuring system arranged in a safety-oriented form having a drive, a stroke sensor and a control for the stroke sensor, and a safety-oriented adjustment control, which is connected to the adjustment device and is arranged to evaluate the sensor signal of the stroke sensor and the signal of the control to control and drive the drive.

[0007] The task of the protective device is to ensure a variable-size working gap of the plastic processing equipment, which can be, for example, a squaring press or a folding bending machine, with the aim of protecting the operator of the plastic processing equipment, who manually inserts the tools for carrying out the plastic processing process into the working gap or manually adjusts their orientation immediately before carrying out the plastic processing process, from the risk of crushing, in particular for the operator's fingers.

[0008] This risk of crushing can result, for example, in the case of a squaring press, when, in order to carry out the squaring process, the upper tool is brought closer to the lower tool forming the workpiece mounting surface for the workpiece, thereby reducing the working gap and thus creating a risk of the operator's fingers, hand or forearm becoming pinched in the working gap between the upper tool and the lower tool or between the upper tool and a workpiece inserted in the working gap.

[0009] In the case of folding and bending machines, the working gap is delimited by a hold-down holder for the workpiece and a workpiece placement surface or a workpiece placed on the workpiece placement surface, which is brought closer to the workpiece placement surface while reducing the working gap in order to fix the workpiece for the subsequent folding and bending process. Here too, due to the reduction in the working gap when the hold-down holder approaches the workpiece placement surface, there is a risk that the fingers, hands or forearms of the operator will be pinched in the working gap.

[0010] Correspondingly, the task of the protective device is to secure the working gap by stopping the process of approaching the upper tool to the lower tool or the workpiece placement surface, as long as the operator intervenes in the working gap and the working gap has already been reduced in a manner that creates a danger to the operator.

[0011] For this purpose, the light source arranged therefor advantageously provides a light beam in the wavelength range of 360 nm to 850 nm, in particular a monochromatic light beam. This light beam can be provided, for example, as a single light beam, in particular as a laser beam, as an arrangement of parallel or aligned light beams in the form of a light curtain, or as a strip-shaped light beam arrangement. Advantageously, it is provided that the optical axis of the light source is oriented parallel to the lower edge of the upper tool. Particularly advantageously, it is provided that the light beam extends along the entire lower edge of the upper tool, thereby covering the entire width of the working gap.

[0012] The receiver is an electrical or electronic component, in particular from the group consisting of a photosensitive diode, a photosensitive diode array, a CCD camera chip, which is designed to receive the rays of the light beam and to provide an electric sensor signal. Advantageously, the receiver is arranged with respect to the light source in such a way that all rays of the light beam enter the receiver if there is no obstructing contour in the light path between the light source and the receiver. The receiver provides an electric sensor signal to a photoelectric switch control configured in a safety-oriented manner, which electric signal can be an analog signal or a coded digital signal. The electric sensor signal represents in particular the light intensity of the rays of the light beam received by the receiver. In the photoelectric switch control, the electric sensor signal is evaluated, in particular with the aid of threshold values ​​stored in the photoelectric switch control, so that it can be determined whether the light beam provided by the light source entered the receiver unobstructed or whether an obstructing contour, for example a finger or a hand of an operator, is present in the light path between the light source and the receiver.

[0013] The photoelectric switch control configured in this safety-oriented manner is in particular configured for redundant processing of the electric sensor signal of the receiver. This redundancy in the processing of the sensor signal can be realized, for example, by using two independently operating processors in the photoelectric switch control, both of which process the sensor signal of the receiver. The photoelectric switch control is in particular configured for providing a stop signal if, during the redundant processing of the sensor signal, a difference occurs between the two processing results of the sensor signal that is greater than a given maximum difference. Instead of providing this stop signal, the photoelectric switch control can also be configured for providing a release signal, which is only output if no interruption of the light beam or an exceedance of a given maximum difference between the two processing results of the sensor signal occurs.

[0014] In order to ensure the advantageous protective effect of the protection device, it is provided that the light source and the receiver are mounted on an adjustment device, which itself is mounted on the machine frame of the plastic processing machine or on the upper tool or on a guide for the upper tool. By means of this adjustment device, a linear relative movement of the light source and the receiver can be performed along an axis of movement, which is determined by the relative movement between the upper tool and the lower tool or between the upper tool and the workpiece mounting surface. Typically, this axis of movement is oriented vertically.

[0015] The adjustment device comprises a drive that can be driven by a photoelectric switch control to realize the desired relative movement of the light source and the receiver along the movement axis. Purely for example, the drive consists of an electric motor, for example a stepping motor with an integrated transmission that converts the rotary movement of the electric motor into the desired linear movement. Alternatively, the drive can also be configured, for example, as an electrodynamic linear direct drive or a fluid-operated linear cylinder. The linear movement provided by the drive can be introduced into a carrier part that is arranged on the machine frame or upper tooling for linear movement, on which the light source and the receiver are mounted together. Alternatively, the light source and the receiver can each be mounted separately on the machine frame or upper tooling for linear movement and coupled to the drive via traction means, for example a toothed belt or a traction rope, in order to ensure a synchronous movement of the light source and the receiver. In another alternative embodiment of the drive, both the light source and the receiver are assigned a respective drive unit, which are configured as an electric motor, an electrodynamic linear direct drive or a fluid-operated linear cylinder, each with a transmission.

[0016] Furthermore, the adjustment device comprises a stroke measurement system configured in a safety-oriented manner, which is configured to detect the position of the light source and the light receiver relative to the machine frame or the upper tooling. To ensure that the position of the adjustment device relative to the machine frame or the upper tooling is detected in a safety-oriented manner, the stroke measurement system comprises a stroke sensor and a management unit for the stroke sensor.

[0017] In this case, the stroke sensor has the position resolution required to measure the position of the adjustment device, while the function of its management part is defined as allowing the adjustment control part to manage the validity of the stroke sensor signal.

[0018] For example, it can be specified that the stroke sensor is capable of achieving a position resolution of 0.1 mm and that the control unit has a number of magnetic sensors or a time measuring device arranged along the adjustment path of the adjustment device. The task of this adjustment control unit is to check whether the sensor signal of the stroke sensor is valid based on the signal of the control unit.

[0019] If the management unit is, for example, composed of a magnetic sensor, the adjustment control unit can determine, based on the stroke sensor signal, where the light source and the light receiver are approximately located and compare this approximate position information with the sensor signal of the stroke sensor.

[0020] When this management unit is constituted by a time measuring device, the adjustment control unit can calculate the operating time length of the drive unit of the adjustment device, and from this operating time length and the known speed of the adjustment device, determine the approximate positions of the light source and the light receiver, and can compare the approximate positions with the sensor signal of the stroke sensor.

[0021] The stroke sensor can be configured as a relative measurement system, for example by detecting the rotation angle of the drive motor, for example on the basis of pulses of a scanning sensor configured to scan the blades of a propeller fan of the drive motor.

[0022] The combination of the stroke sensor and the control unit described above is also called a two-channel redundant measurement system, since it compares information from two different signal sources.

[0023] Particularly advantageously, it is provided that this control is also configured as a stroke sensor. Therefore, in particular, two stroke sensors of the same design can be used, which supply the sensor signal to the adjustment control. Alternatively, technically completely different stroke sensors can also be used, whereby a variety of redundancies are realized. At least one of these stroke sensors can be configured to directly detect stroke information, for example, as in the case of scanning a scale extending along the movement axis in an optical or magnetic sensor. Alternatively, one or both stroke sensors can be configured to indirectly measure the stroke, in which case, for example, repeated events during the movement are detected. It is provided that these stroke sensors are used purely for detecting the rotation of the drive shaft of the electric motor or of the threaded spindle, so that, for example, the adjustment path of the adjustment device can be deduced from the number of rotations, knowing the characteristics of the transmission downstream of the electric motor. Alternatively, scanning of the teeth of a toothed belt drive can also be performed to detect the position.

[0024] Alternatively, the stroke sensor can be realized as an absolute measuring system, for example by scanning a glass scale with a unique Gray code. In this case, the control can be configured to check whether each newly occurring sensor signal of the stroke sensor is indeed located within a given sequence of the sensor signals that have occurred previously in time, thereby eliminating the occurrence of measurement errors of the absolute measuring system. Such a stroke measuring system is called single-channel, since there is only one signal source, and the safety-oriented properties of the form are ensured by an additional signal evaluation unit.

[0025] In this safety-oriented control system, redundant processing of the sensor signals coming from the stroke measuring system is performed. For this purpose, it can be provided, for example, that the control system has two processors, in particular two processors that are technically differently designed and programmed, operating independently of one another, each processing one of the sensor signals of the stroke measuring system. It can also be provided that, after the processing of the sensor signals, a comparison of the resulting position information is carried out between the two processors, and that if both position information are within a given tolerance range, the detected position value is assumed to be correct. In this case, the control system can use the detected position signal to trigger further work steps of the plastic processing machine. For example, the control system can supply a release signal to the machine control, so that the machine control can initiate a movement of the upper tool by subsequent actuation of a corresponding operating switch, for example a foot switch.

[0026] Alternatively, redundant signal processing in the adjustment control can be realized by detecting two positional information and then feeding the stroke measuring system signals to two independent calculation algorithms in a single processor for comparison with each other, in which case it is assumed that the detected position value is correct when both positional information are within a given tolerance range.

[0027] Advantageous refinements of the invention are the subject of the dependent claims.

[0028] It is an object of the present invention for the adjustment and control to have a communication interface, which is configured to receive control information from the machine control and to output safety information to one or more of the machine control, the photoelectric switch control and the safety control. In this case, it is provided that the protection device is configured as a system that operates sufficiently autonomously, and that this system is integrated into a plastic processing machine having a machine control that is not configured in a safety-oriented manner and a safety control that is configured in a safety-oriented manner. In this case, the communication interface of the adjustment and control is responsible for communicating with the machine control, so that control information, such as for example the dimensions of the tool, in particular the tool height, can be obtained from the machine control.

[0029] On the other hand, the communication interface is responsible for outputting safety information which can be supplied to one or more of the machine control, the photoelectric switch control and the safety control. The safety information can be, for example, a release signal indicating that the protection device has reached a protection position required for a defined plastic processing process. Correspondingly, the communication interface has a first communication area for communication with the machine control, which can be configured, for example, as a bus interface and, if necessary, also for bidirectional communication with the machine control, in particular in bus mode.

[0030] Additionally, the communication interface may have a second communication area for communicating with the photoelectric switch control and / or the safety control, via which communication area, for example, a release signal may be supplied.

[0031] In a second aspect of the invention, the object of the invention is achieved by a bending machine, which comprises a machine platform on which a machine table having a workpiece placement surface configured for placement of a workpiece is formed, an upper tool positioned on the machine platform so as to move linearly along a motion axis and assigned to a drive device, which determines a working gap whose size can be changed relative to the machine table, a machine control unit for supplying drive energy to the drive device, a safety control unit for stopping the drive motion of the drive device, and a protection device for ensuring the working gap, the protection device comprising a light source for supplying a light beam, a light receiver arranged opposite the light source for receiving the light beam of the light beam, and a photoelectric switch control unit configured in a safety-oriented form for redundantly processing a sensor signal of the light receiver, The protection device comprises an adjustment device mounted on the machine bed or upper tool and configured to provide linear movement of the light source and the light receiver along the motion axis, the adjustment device comprising a drive unit and a stroke measurement system configured in a safety-oriented configuration having a stroke sensor and a control unit for the stroke sensor, the protection device comprising a regulation control unit configured in a safety-oriented configuration to process, in particular redundantly process, sensor signals of the stroke sensor and the control unit and to control and drive the drive unit, the regulation control unit being electrically connected to the machine control unit to receive control signals.

[0032] The bending machine can be configured, for example, as an angling press or a folding bending machine, and comprises a machine table with a workpiece placement surface configured as a component part of the machine bed. In the case of an angling press, it can be specified that this machine table with the workpiece placement surface is constituted by a lower tool, also called a matrix, which is usually fixed stationary on the machine bed. In an angling press, the variable working gap is determined by the distance between the lower edge of an upper tool, which is placed on the machine bed for linear movement, and the upper edge of a lower tool, which is fixed on the machine bed. In a folding bending machine, the working gap is determined by a hold-down holder, which is placed on the machine bed for linear movement, and the workpiece placement surface.

[0033] The linear movement of the upper tool or the hold-down holder is realized by a drive, which can be, for example, a combination of a hydraulic pump and one or more hydraulic cylinders or an electric motor followed by a transmission. In any case, it is provided that the machine control is configured to supply drive energy, in particular electric drive energy, to the drive in order to bring about a desired relative movement of the upper tool or the hold-down holder with respect to the lower tool or the workpiece placement surface, thereby bringing about an increase or decrease in the working gap. With respect to the machine control, it is taken as a starting point that the control is not configured in a safety-oriented manner, i.e. in particular does not have redundant signal processing. Rather, the machine control is configured to execute a given operating program for the bending machine and to bring about the movements required therefor, in particular movements of the upper tool or the hold-down holder.

[0034] For the safe operation of this bending machine, a safety control configured in a safety-oriented manner is provided, the task of which is to stop the supply of drive energy from the machine control to the drive device, for example by interrupting the electrical connection between the machine control and the drive device or a relay connected to the machine control and the drive device, and to ensure that the bending machine comes to a standstill as quickly as possible, in particular with respect to the upper tool or the hold-down holder.

[0035] The safety control is connected to the already mentioned protective device which is arranged for optically monitoring the working gap. Furthermore, the safety control can be connected to an emergency stop switch which can be operated directly by an operator in a critical situation in order to trigger an emergency stop of the bending machine. The safety control is in particular arranged to effect a switch-off of the drive for the bending machine when a safety-oriented switch-off signal arrives from the photoelectric switch control and / or when no safety-oriented release signal is applied from the photoelectric switch control.

[0036] In an improved configuration of the bending machine, it is provided that the regulating control is integrated into the photoelectric switch control, so that a processor architecture, typically provided for the photoelectric switch control, e.g. consisting of two or more processors, can also be utilized for the functions of the regulating control, without having to make compromises regarding independent signal processing.

[0037] In another embodiment of the bending machine, it is provided that the regulating control has a communication interface, which is configured, as already mentioned above, to receive control information of the machine control and to output safety information to one or more of the machine control, the photoelectric switch control and the separately configured safety control. Advantageously, it is provided that the regulating control can operate completely autonomously, i.e. does not require any further information from further components, such as the photoelectric switch control or the safety control, for its function, except for the electrical energy supply and the communication of the safety control with the machine control, which is particularly important when retrofitting the protection device to an existing bending machine.

[0038] Advantageously, the adjustment device of the bending machine has drives that are assigned individually to the light source and the receiver, respectively. This facilitates the integration of the protection device in the bending machine, since each drive can be mounted in a convenient position on the bending machine and no mechanical coupling between the light source and the receiver has to be considered. For example, it is provided that only the drive for the receiver is provided with a stroke measurement system with a redundantly configured sensor arrangement, while the drive for the light source is provided without a stroke measurement system. In this case, it is provided that when the position of the receiver is adjusted, a corresponding adjustment of the position of the light source is performed, and by evaluating the sensor signals of the receiver, the correct orientation of the light source relative to the receiver can be checked and, if necessary, corrections can be made with respect to the drive of the light source.

[0039] In a third aspect of the invention, the object of the invention is achieved by a method for operating a bending machine, which comprises the steps of: supplying information about the tool height of an upper tool of the bending machine from a machine control of the bending machine to an adjustment control assigned to the bending machine and configured in a safety-oriented form of an adjustment device; driving a drive unit of the adjustment device by the adjustment control in order to displace, by a linear adjustment movement, a light beam provided by a light source and a receiver arranged opposite the light source to a reference position located near a given position relative to the lower edge of the upper tool, calculated from the tool height; and performing a position detection during the linear adjustment movement of the light source and the receiver relative to the upper tool, which position detection is performed by the adjustment control performing processing, in particular redundant processing, of a stroke signal of a stroke sensor of the adjustment device and a signal of a management unit of the adjustment device.

[0040] In a first step of the method, information about the tool height is provided from the machine control to the adjustment control, which is configured in a safety-oriented manner. This tool height is the extension of the upper tool in the direction of the movement axis, which movement axis represents the spatial direction in which the approach and retract movements between the upper tool and the workpiece placement surface can be performed. Basically, the upper tool is mounted on a carriage, which is placed on the machine bed so that it can be moved linearly, and this carriage can be moved by a drive device.

[0041] When the carriage occupies a maximum distance from the workpiece placement surface, the maximum extension of the working gap is obtained as the difference between this maximum distance and the tool height of the upper tool. In order to be able to achieve the desired retention of the working gap, it is necessary that the light source and the receiver arranged opposite it are located in front of the lower edge of the upper tool in the direction of the closing movement in such a way that, when the light beam provided by the light source is interrupted, a stop state of the upper tool can be achieved without causing any risk of crushing injuries to the operator. The distance between the lower edge of the upper tool and the light beam is calculated, inter alia, from the requirement for a minimum clearance to be left in order to prevent crushing injuries and the braking distance of the upper tool. This braking distance of the upper tool depends, inter alia, on the feed rate of the upper tool during the closing movement, the processing time of the photoelectric switch control regarding the signal of the receiver and the processing time of the safety control regarding the arrival of the switch-off signal of the photoelectric switch control.

[0042] After the information on the tool height of the upper tool is supplied to the adjustment control, the determination of a given position and a reference position is performed in the adjustment control based on the supplied tool height, the given position being the position that the lower edge of the upper tool would theoretically occupy in a given machine coordinate system of the bending machine based on the supplied information on the tool height, the reference position being the position that the light source and the receiver must occupy relative to the upper tool in order to achieve an arrangement of the light beam close to the lower edge of the upper tool and therefore close to the given position.

[0043] Advantageously, this reference position is placed maximum 1 mm below the given position and therefore below the lower edge of the upper tool.

[0044] After the given position and the reference position have been identified, the adjustment control unit drives the drive unit of the adjustment device in such a way that a linear relative movement of the light source and the light receiver in the direction of the reference position is achieved in particular.

[0045] In this case, the position determination for the adjusting device is performed in a safety-oriented adjustment control, which is configured in a manner that is directed toward safety. The adjusting device is equipped with both the light source and the light receiver, and thus determines the spatial position of the light beam provided by the light source relative to the lower edge of the upper tool. This position is determined on the basis of the sensor signals of a stroke sensor assigned to the adjusting device and the signal of a control unit of the adjusting device. The sensor signals of the stroke sensor and the signal of the control unit (which can be, for example, a pure stroke sensor or a time measuring device) are processed separately from one another in the adjustment control in order to determine therefrom two positional information. These two positional information are then compared with one another, and if these two positional information lie within a given tolerance range, a position value is output, which is used, for example, for the position control of the adjusting device.

[0046] Advantageously, it is provided that during the relative movement of the adjustment device with respect to the upper tool, new position values ​​are continuously determined, thereby ensuring (closed-loop) controlled positioning of the adjustment device with respect to the entire linear displacement movement of the light source and the receiver.

[0047] As long as the adjustment device positions the light source and receiver relative to the upper tooling so that the light beam is in the nominal position, the first step of the bending machine operating method is completed.

[0048] In an improved version of the method, it is provided that the adjustment control drives the adjustment device in such a way that before the displacement of the light source and the receiver to the reference position, the displacement of the light source and the receiver to the maximum distance for the given position is performed, and then the displacement of the light source and the receiver to the reference position is performed. This intermediate step should ensure that erroneous information about the tool height of the upper tool does not adversely affect the protective effect of the protection device. In this intermediate step, the light beam passes through a large part of the working gap so that areas that are possibly below the given position of the upper tool can be detected. If an interruption of the light path between the light source and the receiver occurs when performing the adjustment movement, a stop of the bending machine is performed.

[0049] In another embodiment of the method, it is provided that the adjustment control drives the adjustment device starting from the reference position, such that the light source and the receiver are displaced in the direction of the gap between the reference position and a given position of the upper tool. In the steps of the method, the light source and the receiver, and therefore also the light beam, are moved in the direction opposite to the closing direction of the upper tool. This usually results in the approach of the light beam to the lower edge of the upper tool.

[0050] Advantageously, the method is provided in such a way that if, during the displacement of the light source and the receiver in the direction of the gap between the reference position and the given position, a given maximum distance relative to the reference position is reached without interrupting the light beam provided by the light source, the adjustment control outputs an error signal, and if, during the displacement of the light source and the receiver in the direction of the gap between the reference position and the given position, an interruption of the light beam provided by the light source occurs before reaching the given maximum distance relative to the reference position, the adjustment control stops the movement of the adjustment device and, starting from this stop position, moves the light source and the receiver to a given safe position after reversing the drive direction.

[0051] If the machine control provides correct information on the tool height of the upper tooling and the corresponding steps carried out by the adjustment control are likewise carried out correctly, then it is expected that the light beam will be blocked by the upper tooling due to its displacement in the direction of the given position from the reference position, so that an interruption of the light path will occur. As long as this blocking of the light beam occurs before reaching a given maximum distance from the reference position, then it can be concluded that all the previous steps of the method have been carried out correctly and that the upper tooling really has the tool height provided by the machine control.

[0052] On the other hand, if no interruption of the light path occurs when the light beam is displaced from the reference position in the direction of the given position, so that the light beam reaches a given maximum distance from the reference position without being interrupted, it must be concluded that the information about the tool height of the upper tool is incorrect or that at least one error has occurred during the implementation of the preceding steps of the method. In both cases, an error signal is output from the adjustment control to the safety control, which prevents the start of the bending machine. Correspondingly, the bending process is not carried out in this case.

[0053] Advantageously, for the method, it is provided that the control device in this safety-oriented form drives the adjustment device in such a way that the light source and the light receiver are arranged at a given safe distance from the position of the lower edge, which safe distance is determined in particular by the braking distance of the upper tool and by the respective safety regulations to be observed when operating the bending machine.

[0054] In another embodiment of the method, it is provided that the safety-oriented control device outputs a release signal when the light source and the receiver are positioned at a given safe distance from the position of the lower edge, and that an energy flow is supplied from the machine control to the drive system assigned to the upper tool in order to realize a movement to bring the upper tool and the workpiece mounting surface of the bending machine closer together, and that when the light beam is interrupted, the photoelectric switch control outputs a stop signal or switches off the release signal, and a safety control connected to the safety-oriented control device realizes the blocking of this energy flow when the stop signal arrives.

[0055] Advantageous embodiments of the invention are shown in the drawings. [Brief description of the drawings]

[0056] [Figure 1] FIG. 1 shows a front view of a bending machine with a machine control, an optical safety device and a safety control assigned thereto, which is configured purely as a folding bending machine, for example. [Diagram 2]FIG. 2 is a schematic partial cross-sectional side view of the bending machine of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0057] The bending machine 1 shown in Figures 1 and 2, which is configured purely, for example, as a folding bending machine, comprises a machine bed 2, on which a workpiece table 3 is formed, which has, for example, a flatly configured workpiece placement surface 4. According to the drawings in Figures 1 and 2, this purely, for example, rectangular workpiece placement surface 4 is oriented horizontally and extends from a front edge 32, which can be seen in Figure 1, to a rear edge 33, which can be seen in Figure 2. Furthermore, this workpiece placement surface 4 extends from a left side edge 34 to a right side edge 35.

[0058] Furthermore, a bending beam 5 is pivotally arranged on the machine bed 2, the longest edge 31 of which runs along the front edge 32 of the workpiece placement surface 4. The bending beam 5 is attached to the machine bed 1 in its opposing end regions by means of swivel joints 6, 7. The swivel joints 6, 7 have a common pivot axis 8 oriented parallel to the workpiece placement surface 4.

[0059] The working surface 10 of the bending beam 5 can be pivoted from the rest position of FIG. 1, in which the working surface 10 is arranged parallel to and in the same plane as the workpiece placement surface 5, by a pivoting movement of the bending beam 5 by means of the pivoting drive 31, into an operating position shown by the dashed lines in FIG. 2. In this operating position, the working surface 10 is, for example, perpendicular to the workpiece placement surface 4, although other angular positions are also possible. The initiation of the pivoting movement of the bending beam 5 is effected by a foot switch 9, which is connected to a machine control 12, which can control the movement of the pivoting drive 31 in an open-loop or closed-loop manner.

[0060] To fasten a purely plate-shaped workpiece 41, for example, shown in dotted lines in Fig. 2, to the workpiece table 3, there is provided an upper tool 21, also called a clamping beam, which is movably attached to the machine bed 2. This upper tool 21 is fixed to a carriage 20, which is guided for linear movement on guide posts 15, 16 fixed to the machine bed 2 by means of guide means, not shown, on both sides. The distance 22 between the lower edge 23 of the upper tool 21 and the workpiece table 3 can be set by means of a spindle drive 17 with an electric motor 18 and a drive spindle 19. The movement of the carriage 20 with the upper tool 21 attached between a first operating position, shown in Fig. 1 with a maximum distance 22 from the workpiece placement surface 4, and a second operating position, not shown, with a minimum distance from the workpiece placement surface 4, can thus be carried out along a movement axis 24 indicated by a double arrow. In this case, when the upper tool 21 moves between the first operating position and the second operating position, the lower edge 23 of the upper tool 21 moves within a motion plane 25, indicated by a dashed line in FIG. 2, which includes the lower edge 23 and is oriented perpendicular to the workpiece mounting surface 4.

[0061] In order to ensure the working gap 15, an optical safety device 51 is assigned to the upper tool 21, which can in particular be fixed to the carriage 20. This optical safety device 51 comprises a light source 52 and a receiver 54. A laser beam 56, which can also be called a light beam, represented by a dashed line, travels between this light source 52 and the receiver 54 assigned to it. Furthermore, this optical safety device 51 comprises a photoelectric switch control 71.

[0062] The light sources 52 can be configured, for example, as discrete laser diodes and are advantageously designed to emit the respective laser beams 56 in the form of parallel light beams with an approximately dot-like cross section. For example, the receiver 54 is oriented in such a way that the laser beams 56 impinge on the receiver 54 in an area of ​​maximum light sensitivity (not shown). The light sources 51 and the receiver 52 are electrically connected via signal lines 53, 55 to a photoelectric switch control 71. The photoelectric switch control 71 is designed in a safety-oriented manner and comprises two processors, not shown in detail, with which the sensor signal of the receiver 52 arriving via the signal line 55 can be redundantly processed. If the sensor signal of the receiver 52 indicates that the laser beam 56 has been interrupted or that a deviation has occurred between the processing results of the processors of the photoelectric switch control 71, the photoelectric switch control 71 is configured to selectively output a stop signal or switch off the release signal. This realizes activation of the safety control section 81, which is electrically connected to the photoelectric switch control section 71 and will be described in detail later.

[0063] The light source 52 is mounted on a first adjuster 26 capable of linearly moving and displacing the light source 52 with respect to the upper tooling 21, so that the light source 52 can perform a linear relative movement along the movement axis 24 relative to the upper tooling 21. The first adjuster 26 is assigned a first stroke sensor 58 configured to detect the position of the light source 52 with respect to the upper tooling 21.

[0064] The receiver 54 is mounted on a second adjuster 27 which allows linear movement and displacement of the receiver 54 with respect to the upper tooling 21, so that the receiver 54 can perform a linear relative movement along the axis of movement 24 relative to the upper tooling 21. A second stroke sensor 59 is assigned to the second adjuster 27 and is configured to detect the position of the receiver 54 with respect to the upper tooling 21.

[0065] For example, it is provided that the linear movement of the adjusters 26, 27 relative to the upper tool 21 is coordinated by an adjustment control 83 configured in a safety-oriented manner so that the light source 52 and the light receiver 50 are always opposed to each other. To this end, the adjustment control 83 is connected to the first adjuster 26, the second adjuster 27, the first stroke sensor 58 and the second stroke sensor 59 via electrical wiring (not shown).

[0066] Purely for example, it can be provided that this first regulator 26 always follows the second regulator 27 so that the receiver 54 receives maximum illumination by the light source 52 .

[0067] The adjustment control unit 83 is configured to evaluate the stroke signal of the first stroke sensor 58 and the stroke signal of the second stroke sensor 59 and control and drive the first regulator 26 and the second regulator 27.

[0068] These two stroke sensors 58, 59 are each assigned to one of the two regulators 26, 27 which can operate independently of one another, so that no redundant sensor signals are generated for the respective positions of these regulators 26, 27. However, in order to be able to meet the requirements for a safety-oriented position detection at least for the regulator 27 assigned to the receiver 54, this regulator 27 is assigned a further third stroke sensor 60 which is also connected to the regulator control 83 via electrical wiring, not shown. In this case, the second stroke sensor 59 and the third stroke sensor 60 form a redundantly operating stroke measurement system 70 for the regulator 27.

[0069] In this case, the first regulator 26, the second regulator 27 and the stroke sensors 58, 59, 60 constitute an adjusting device 28 that is electrically connected to an adjustment control section 83 and can be driven by this control section.

[0070] Furthermore, this control unit 83 comprises a first processor 84 and a second processor 85 for internal processing of the sensor signals of the stroke sensors 58, 59, 60, so that it is possible to redundantly calculate position values ​​on the basis of these sensor signals. This is a necessary prerequisite for the safety-oriented design of the control unit 83.

[0071] The safety control section 81 is electrically connected to the photoelectric switch control section 71 and configured to drive a switch-off device 82. The switch-off device 82 can be, for example, an electrical protector for the electric motor 18. This allows the safety control section 81 to realize the stop of the drive motor 18 by stopping the energy supply, even though the machine control section 12 is supplying electric energy to the electric motor 18. For example, the safety control section 81 is specified to be configured to check at regular time intervals whether a release signal is generated from the photoelectric switch control section 71, and to drive the switch-off device if the release signal is not generated.

[0072] From the side view according to FIG. 2, only the receiver 54 is visible, whereas the light source 52 assigned to it is not shown in FIG.

[0073] The mode of operation of the bending machine 1 can be described as follows: first, the upper tool 21 is fixed on the carriage 20 and the tool height 92 of the upper tool 21 is supplied to the machine control 12 via an input device, not shown. The machine control 12 then transmits this tool height 92 to the adjustment control 12, which then calculates a given position, which corresponds to the position that the lower edge 23 of the upper tool 21 must occupy relative to the first and second adjusters 26 and 27, as long as the tool height 92 is correctly entered and the correct upper tool 21 is installed. Furthermore, the adjustment control 83 calculates a reference position, which is located in the immediate vicinity of the given position and which represents the place where the light beam provided by the light source 52 is just not yet interrupted by the obstructing contour of the upper tool 21.

[0074] An optional calibration process can then be defined for the adjustment control 83, which is to be defined in particular after an assembly operation on the optical safety device 51. For this calibration process, the adjustment control 83 drives the two adjusters 26 and 27 in such a way that the laser beam 56, also called the light beam, is displaced to a reference position located directly below the lower edge 23 of the upper tool 21. If this results in an uninterrupted laser beam, the two adjusters 26 and 27 are driven in such a way that the laser beam 56 occupies a given safety distance with respect to the reference position. The machine control 12 then triggers the spindle drive 17, during which a test bar with a defined diameter is placed on the workpiece placement surface 4. When the laser beam 56 is interrupted by the test rod and the spindle drive 17 is subsequently switched off by the coordinated action of the photoelectric switch control 71, the safety control 81 and the switch-off device 82, braking of the upper tool 21 occurs so that the test rod is no longer in contact with the upper tool, the positions of these two adjusters 26, 27 can be stored in the adjustment control 83 and used for a subsequent adjustment process, which ends the calibration process and allows the bending machine 1 to be brought into standard operation.

[0075] After a further exchange of the upper tooling 21, the machine control 12 transmits the tool height 92 of the new upper tooling 21 to the adjustment control 83, which then calculates the new given position and the new reference position.

[0076] Subsequently, the photoelectric switch control 83 drives the two adjusters 26 and 27 so that the laser beam 56 is displaced to a reference position located immediately below the lower edge 23 of the upper tooling 21. As long as the displacement of the light source 52 and the receiver 54 to the reference position does not cause the laser beam to be interrupted, the adjustment control 83 performs the next drive of the two adjusters 26 and 27 in a step defined only as an option, so that the laser beam 56 is displaced in the direction of the lower edge 23 of the upper tooling 21. In this case, if the optical path between the light source 52 and the receiver 54 is blocked by the upper tooling 21 before the laser beam 56 occupies the maximum distance relative to the reference position, resulting in the laser beam 56 being interrupted, the adjustment control 83 realizes a reversal of the movement of the two adjusters 26, 27 in order to move the light source 52 and the receiver 54 to a predetermined safe distance relative to the given position, starting from the position where the interruption of the laser beam 56 occurred. On the other hand, if, when the laser beam 56 is displaced in the direction of the lower edge 23 of the upper tool 21, the laser beam is not interrupted until the laser beam 56 occupies its maximum distance from the reference position, then it must be concluded that the tool height provided by the machine control 12 is incorrect and therefore the start-up of the bending machine 1 must be stopped, so that the adjustment control 83 provides a corresponding signal to the communication interface 86 to the safety control 81.

[0077] When the interruption of the laser beam 56 is confirmed and the laser beam 56 occupies a given safe distance from the lower edge 23 of the upper tool 21, the adjustment control unit 83 can supply a release signal to the safety control unit 81, so that the upper tool 21 can then be brought close to the workpiece mounting surface 4 in order to clamp the workpiece 41 by operating the foot switch 9.

[0078] If the laser beam 56 is interrupted during the approach movement of the upper tool 21 to the workpiece placement surface 4, the photoelectric switch control 83 supplies a corresponding signal to the communication interface 86 for the safety control 81, which in turn drives the spacing device 82 in order to achieve the fastest possible braking of the carriage 20 to which the upper tool 21 is fixed.

[0079] For example, it may be provided that a drop in the sensor signal of the receiver 56 occurs in the photoelectric switch control 83 when a given minimum clearance between the lower edge 23 of the upper tool 21 and the workpiece placement surface 4 falls below.

Claims

1. A protection device (51) for securing a working gap (14) of a plastic processing device (1), comprising: a light source (52) configured to provide a light beam (56) within the working gap (14); a receiver (54) disposed opposite the light source (52) and configured to receive light rays of the light beam (56); A photoelectric switch control unit (71) configured to redundantly process the sensor signal of the photoreceiver (54) and configured in a safety-oriented form; an adjustment device (28) mounted on a machine frame or an upper tool (21) of a plastic processing device (1) and configured to provide a linear movement for a light source (52) and a light receiver (54), the adjustment device (28) comprising a drive (26, 27) and a stroke measurement system (58, 59, 60) configured in a safety-oriented form having a stroke sensor and a control part for the stroke sensor; an adjustment control unit (83) connected to the adjustment device (28), configured to evaluate a sensor signal of the stroke sensor and a signal of the management unit, and configured to control and drive the drive units (26, 27), and configured in a safety-oriented form; A protective device comprising:

2. A protection device (51) according to claim 1, The protection device is characterized in that the adjustment control unit (83) has a communication interface (86), which is configured to receive control information from the machine control unit (12) and output safety information to one or more of the machine control unit (12), the photoelectric switch control unit (71) and the safety control unit (81).

3. a machine bed (2) on which a machine table (3) having a workpiece placement surface (4) configured for placing a workpiece (41) is formed; an upper tool (21) supported on the machine bed (2) so as to be linearly movable along a movement axis (24) and assigned a drive device (17), the upper tool (21) defining a variable-size working gap (14) relative to the machine table (3); A machine control unit (12) that supplies driving energy to the driving device (17); A safety control unit (81) that stops the driving motion of the driving device (17); A protection device (51) for securing the working gap (14) includes a light source (52) for supplying a light beam (56), a light receiver (54) for receiving the light beam (56) disposed opposite the light source (52), and a photoelectric switch control unit (71) configured in a safety-oriented form for redundantly processing a sensor signal of the light receiver (54); A bending machine (1) comprising: The protection device (51) comprises an adjustment device (28) mounted on the machine bed (2) or on the upper tooling (21) and configured to provide a linear movement of the light source (52) and the light receiver (54) along the motion axis (24), The adjusting device (28) comprises a drive (26, 27) and a stroke measuring system (59, 60) configured in a safety-oriented manner, the stroke measuring system having a stroke sensor and a control unit for the stroke sensor, the protection device (51) comprises an adjustment control section (83) configured in a safety-oriented manner, the adjustment control section being configured to process sensor signals of the stroke sensor and the management section, in particular to process them redundantly, and to control and drive the drive sections (26, 27); The adjustment control (83) is electrically connected to the machine control (12) for receiving a control signal. Bending machine.

4. 4. The bending machine according to claim 3, A bending machine, characterized in that the adjustment control (83) is integrated into a photoelectric switch control (71).

5. 4. The bending machine according to claim 3, The bending machine is characterized in that the adjustment control unit (83) has a communication interface (86), which is configured to receive control information from the machine control unit (12) and output safety information to the photoelectric switch control unit (71) and / or a separately configured safety control unit (81).

6. A bending machine according to claim 3, 4 or 5, A bending machine, characterized in that the adjustment device (28) for the light source (52) and for the light receiver (54) each has an individually assigned drive unit (26, 27).

7. A method of operating a bending machine (1), comprising the steps of: - supplying information about the tool height of the upper tool (21) of the bending machine (1) from a machine control (12) of the bending machine (1) to an adjustment control (83) assigned to the bending machine (1) and configured in a safety-oriented manner for the adjustment device (28); driving the drive parts (26, 27) of the adjustment device (28) by means of the adjustment control part (83) in order to displace the light beam (56) provided by the light source (52) and the light receiver (54) arranged opposite the light source (52) by a linear adjustment movement to a reference position placed adjacent to a given position calculated from the height of the tool relative to the lower edge (23) of the upper tool (21); - performing a position detection during the linear adjustment movement of the light source (52) and the light receiver (54) relative to said upper tool (21), said position detection being carried out by processing the stroke signals of the stroke sensors (59, 60) of the adjustment device (28) and the control signals of the management of the adjustment device (28), in particular by a control control (83) which performs redundant processing; The method according to claim 1,

8. 8. The method of claim 7, The method is characterized in that the adjustment control unit (83) drives the adjustment device (28) to perform displacement of the light source (52) and the light receiver (54) to the reference position after displacing the light source (52) and the light receiver (54) to a maximum distance for a given position before displacing the light source (52) and the light receiver (54) to the reference position.

9. 9. The method according to claim 7 or 8, The method is characterized in that the adjustment control unit (83) drives the adjustment device (28) starting from the reference position so as to displace the light source (52) and the light receiver (54) in the direction of the interval (22) between the reference position and a given position of the upper tool (21).

10. 10. The method of claim 9, said adjustment control unit outputs an error signal when, during a displacement of the light source (52) and the light receiver (54) in the direction of the interval (22) between the reference position and the given position, a given maximum interval with respect to the reference position is reached without interrupting the light beam (56) provided by the light source (52); the adjustment control unit (83) stops the movement of the adjustment device (28) when an interruption of the light beam (56) provided by the light source (52) occurs during the displacement of the light source (52) and the light receiver (54) in the direction of the interval (22) between the reference position and the given position before the given maximum interval with respect to the reference position is reached; The method comprising:

11. The method according to any one of claims 7 to 10, The method according to the present invention, characterized in that the adjustment control unit (83) drives the adjustment device (28) so that the light source (26) and the light receiver (27) are positioned at a given safe distance from the lower edge position.

12. 12. The method of claim 11, The adjustment control unit (83) outputs a release signal to the machine control unit (12) when the light source and the light receiver are positioned at a given safe distance from the lower edge position; In order to realize an approach movement between the upper tool (21) and the workpiece placement surface (4) of the bending machine (1), an energy flow is provided from the machine control (12) to a drive system (17) assigned to the upper tool (21), a photoelectric switch control (71) outputs a stop signal when the light beam is interrupted, and a safety control (81) connected to the photoelectric switch control (71) realizes the blocking of the energy flow to the drive system (17) when the stop signal arrives; The method comprising:

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