Bending machine and method for operating bending machine

Abstract

To provide a method for operating a bending machine.SOLUTION: A first optical safety protection device 51 is arranged in a handling space 71, and a second optical safety protection device 61 is arranged in a workpiece housing space 72. Additionally, the bending machine has a safety protection control device. The safety protection control device is formed to evaluate a first sensor signal of the first optical safety protection device 51 and a second sensor signal of the second optical safety protection device 61 as well as to stop an operation of a spindle drive device 17 assigned to an upper tool 21, depending on the first sensor signal and / or the second sensor signal. The safety protection control device is formed to switch between a first operation mode in which only the first sensor signal is evaluated and a second operation mode in which only the second sensor signal is evaluated.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a bending machine and to a method for the operation of a bending machine. [Background technology]

[0002] Patent document 1 discloses a rotary bending machine, which: a machine bed having a workpiece table with a workpiece placement surface; a workpiece holder for fastening the workpiece on the workpiece table; and The workpiece table has bending cheeks which are swivelably attached to the workpiece table and which are fixed to the machine bed by means of swivel links, with the swivel axes of the swivel links being aligned concentrically with one another and parallel to the workpiece placement surface, and an optical monitoring device for monitoring the closing movement of the workpiece holder, an optical transmitter for emitting a control beam; It has a receiver for the control beam located opposite the transmitter, wherein the transmitter and receiver are assigned to the pivot link such that the control beam between the transmitter and receiver passes within a sheathing cylinder formed around a pivot axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] European Patent Application Publication No. 2 633 925 A1 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a bending machine by means of which workpieces can be processed, the workpieces having a plurality of bending regions with bending lines, where the bending lines do not necessarily have to be oriented parallel to one another. [Means for solving the problem]

[0005] This problem is solved according to a first aspect of the invention by a bending machine, the bending machine having a machine bed, a workpiece table is formed on the machine bed, the workpiece table having a workpiece placement surface formed for placement of the workpiece, and The bending machine has an upper tool supported on the machine bed so as to be linearly movable along a movement axis, the upper tool has a lower edge disposed adjacent the workpiece receiving surface; the lower edge portion, together with the axis of movement, defines a plane of movement; in said plane of movement, said lower edge portion is movable between an open position for said upper tool and a closed position for said upper tool, The transfer plane separates a handling space, which extends from the upper tool in the direction of a front edge of the workpiece placement surface, from a workpiece receiving space, The workpiece receiving space extends from the upper tool to a rear edge of the workpiece placement surface; and A first optical security device is disposed in the handling volume and a second optical security device is disposed in the processing material receiving volume; and The bending machine has a safety protection control device, the safety control device is configured for evaluating a first sensor signal of the first optical safety device and a second sensor signal of the second optical safety device and for deactivating a spindle drive assigned to the upper tool as a function of the first sensor signal and / or the second sensor signal, The safety control device is configured for switching between a first operating mode, in which exclusively the first sensor signal is evaluated, and a second operating mode, in which exclusively the second sensor signal is evaluated. Effect of the Invention

[0006] It is possible for the bending machine to be designed, for example, as a folding press or a rotary bending machine.

[0007] In the bending press, an upper tool is moved linearly toward a lower tool assigned to the workpiece table, the upper tool having a lower edge portion which embodies the area of ​​the lower edge portion which comes into contact first with the upper side of the workpiece when the deformation process is carried out.

[0008] The contour of the upper tool in a cross-section oriented transversely to the lower edge of the upper tool corresponds essentially to the workpiece contour with the upper side of the workpiece to be processed after the folding and bending process has been carried out.Furthermore, the contour of the lower tool in a cross-section oriented transversely to the lower edge of the upper tool corresponds at least essentially to the workpiece contour with the lower side of the workpiece to be processed after the folding and bending process has been carried out. It is also possible for the lower tool of the folding press to be configured in such a way that its upper side facing towards the upper tool forms the workpiece table and thus the workpiece rest surface.

[0009] In a pivoting bending machine, the workpiece is first pressed against the workpiece-receiving surface of the workpiece table by an upper tool configured as a clamping cheek, the lower edge of the upper tool being formed by the edge of the clamping cheek, which edge is directed towards the user of the bending machine during normal use of the bending machine and has a minimum distance of the clamping cheek from the workpiece-receiving surface. In the subsequent bending step, a clamping cheek, which is pivotally supported on the workpiece table, is pivoted and bends the end region of the workpiece protruding beyond the workpiece table around its lower edge portion.

[0010] In pivoting bending machines as well as in folding presses, the upper tool represents a potential source of danger for the user, since on approach of the upper tool to the workpiece table the working gap bounded by said upper tool and the workpiece table decreases and disappears (i.e. approaches zero) for the performance of the deformation process, and as a result a risk of crushing can arise, for example for the fingers, arms of the user.

[0011] To minimize risk to a user's body parts, the vending machine has a first optical safety device, a second optical safety device, and a safety control device electrically coupled to the first optical safety device and the second optical safety device.

[0012] The safety control device is designed for processing the sensor signals of the first optical safety device and the second optical safety device as well as for deactivating the drive assigned to the upper tool. By way of example, it is intended that the upper tool is assigned an electromechanical or electrohydraulic drive, so that the safety protection control device can, by interrupting the electrical supply of the respective drive, stop the approach movement between the upper tool and the workpiece table or, in some cases, induce a reverse opening movement of the upper tool relative to the workpiece table.

[0013] The first optical safety device and the second optical safety device are arranged such that, upon user intervention within the defined safety space, they provide a sensor signal to the safety control device, which sensor signal triggers deactivation of the drive device. For this purpose, the safety space is divided into a handling space and a workpiece receiving space, the handling space representing a spatial area which runs from the upper tool in the direction towards the front edge of the workpiece placement surface and in which the user typically intervenes when handling the workpiece. The workpiece receiving space extends from the upper tool in the direction toward the front edge of the workpiece placement surface and is essentially used to receive the workpiece, although it cannot be excluded that the user can intervene in the workpiece receiving space.

[0014] The partition between the handling space and the workpiece receiving space is formed by a transfer plane, which is defined by the lower edge of the upper tool and the transfer plane of the upper tool. Typically, the transfer plane is oriented transversely (i.e. perpendicularly) to the workpiece placement surface, which is usually flat and horizontally oriented. The movement plane is the plane in which the lower edge of the upper tool is moved when transitioning between the open and closed positions, and is therefore typically oriented vertically.

[0015] Advantageously, it is provided that the first optical safety device arranged in the handling space has a distance, in particular in the horizontal direction, of 10 mm to 20 mm from the movement plane, and that the second optical safety device arranged in the workpiece receiving space has a distance, in particular in the horizontal direction, of 0 mm to 10 mm from the movement plane.

[0016] In order to be able to guarantee the processing of differently formed processing materials, the safety protection control device is configured in such a way that it can be switched between a first operating mode adapted to a first processing material configuration and a second operating mode adapted to a second processing material configuration.

[0017] In the first operating mode, a workpiece configuration is based on which the workpiece is placed with its lower side on the workpiece placement surface and, starting from an upper side of the workpiece that is oriented parallel to the lower side, a workpiece contour protrudes vertically upward from the upper side of the workpiece. This workpiece contour extends in the direction towards the upper tool in such a way that, after positioning of the workpiece with the bending line intended for deformation below the lower edge of the upper tool, a blocking of a second optical safety device arranged in the workpiece receiving space occurs, which second optical safety device triggers the deactivation of the drive for the upper tool by the safety control device. Accordingly, in order to carry out a processing operation on the workpiece shaped in this way, it is necessary to process exclusively the sensor signals of the first optical safety device.

[0018] In the second operating mode, a workpiece configuration is based on which the workpiece is placed with its lower side on the workpiece placement surface and, starting from an upper side of the workpiece that is oriented parallel to the lower side, a workpiece contour protrudes vertically upward from the upper side of the workpiece. This workpiece contour extends in the direction towards the upper tool in such a way that after positioning of the workpiece with the bending line intended for deformation below the lower edge of the upper tool, a blocking of the first optical safety device arranged in the handling space occurs, this second optical safety device triggering the deactivation of the drive for the upper tool by the safety control device. Accordingly, in order to carry out the processing steps on the workpiece shaped in this way, it is necessary to process exclusively the sensor signals of the second optical safety device.

[0019] Advantageous further configurations of the invention are the subject of the dependent claims.

[0020] The first optical security device comprises: a first lower light source configured to provide a first lower light beam that is parallel to the lower edge; and a first lower light receiving portion configured for receiving the first lower light beam; and The first optical security device comprises: a first upper light source configured to provide a first upper light beam that is parallel to the lower edge; and a first upper light receiving portion configured for receiving the first upper light beam; It is expedient if the first lower light source has a smaller distance from the workpiece placement surface than the first upper light source. The first lower light source and the first upper light source are preferably each laser sources which output a bundle of parallel directed light rays, referred to as a first lower light ray or a first upper light ray, respectively, to a first lower light receiving section or a first upper light receiving section arranged opposite each other. These light sources are preferably designed for providing light of only one wavelength or for providing light within a predefined wavelength spectrum, with particular advantage being provided for these light rays to be in the wavelength range of visible light (from 380 nm to 780 nm) and / or in the adjacent infrared or ultraviolet wavelength range.

[0021] The first lower light receiver and the first upper light receiver are, for example, respectively a light-sensitive diode, in particular a light-sensitive diode, which is sensitive to the provided light, or respectively a number of light-sensitive diodes, or a camera chip, in particular a CCD chip. In one variant of the first optical security device, it is possible that a large optical bundle of rays is provided from a single light source, which bundle of rays is intended to be expanded by means of an optical system into a defined light field or into a number of smaller bundles of rays. In a further variant of the first optical security device, it is possible that the parallel light beams are received by a common light receiver, in particular a camera chip, and a discrete evaluation for the individual light beams and for the sensor signals resulting from these is carried out by the security control device. Advantageously, it is provided that the first lower light beam and the first upper light beam are arranged in a light beam plane, which light beam plane is oriented parallel to the movement plane. Typically, it is intended that the first lower light beam is oriented parallel to the lower edge 23 and the workpiece placement surface and has a distance from said workpiece placement surface of about 6 to 10 mm. Optionally, further light sources and light receivers may be provided to provide additional protection.

[0022] Advantageously, said second optical security device comprises: a second lower light source configured to provide a second lower light beam that is parallel to the lower edge; and a second lower light receiving portion configured for receiving the second lower light beam; and The second optical security device comprises: a second upper light source configured to provide a second upper light beam that is parallel to the lower edge; and a second upper light receiving portion configured for receiving the second upper light beam; It is contemplated that the second, lower light source has a closer spacing to the workpiece placement surface than the second, upper light source. It is particularly advantageous for the configuration of the second optical security device to be similar or identical to the configuration of the first optical security device and to differ from the first optical security device only in that the second optical security device is arranged in the workpiece receiving space.

[0023] In a further aspect of the invention, the safety protection control device, in the first mode of operation, During the closing movement of the upper tool, It is intended that the sensor signal of the first upper light receiving part and the sensor signal of the first lower light receiving part are both evaluated. During the closing movement of the upper tool 21, during which the approach of this upper tool to the workpiece placement surface 4 takes place, in the first operating mode, continuous monitoring of the part of the handling space located immediately in front of the upper tool is provided, since in this part there is a risk of crushing for the user during the closing movement of the upper tool. This is also the case when the upper tool is a clamping cheek of a pivoting bending machine, by means of which the workpiece is fixed on the workpiece table prior to the bending process, or when the upper tool is a clamping cheek of a folding press. The risk of crushing is indeed reduced when the first handling gap between the lower edge and the workpiece-receiving surface is undercut, and additionally when the second handling gap between the lower edge and the workpiece-receiving surface is undercut, but by maintaining monitoring a consistently high reliability level for the closing process can be maintained. By way of example only, the first handling distance is approximately 12 mm, whereas the second handling distance is, for example, approximately 6 mm. In principle, it is based on the fact that starting from the maximum distance between the upper tool and the workpiece placement surface, the upper tool is first approached to the workpiece placement surface with a high approach speed (fast forward stroke) and that, when the first and second handling distances are reached, no switchover to a low approach speed (slow stroke) takes place.

[0024] In a further aspect of the invention, the safety protection control device, in the second mode of operation, fading out the sensor signal of the second upper light receiver when a first engagement interval between the lower edge and the workpiece receiving surface is exceeded; and It is intended that the second lower light receiving portion is formed to fade out the sensor signal when a second engagement interval between the lower edge portion and the workpiece placement surface is exceeded. In so doing, the same considerations as for the first operating mode are the basis, so that for the second operating mode reference may be made to the above explanation for the first operating mode, in particular that the first engagement interval is identical to the first handling interval and / or that the second handling interval is identical to the second engagement interval.

[0025] With regard to the second operating mode, it is based on the fact that the upper tool is first approached to the workpiece placement surface with a high approach speed (fast forward process) starting from the maximum distance between the upper tool and the workpiece placement surface. It is furthermore possible - for example with the aid of a displacement measuring system assigned to the upper tool or an assigned first switching device - that a switchover to a low approach speed (slow stroke) takes place immediately before the arrival of the first engagement interval. A fade-out of the sensor signal of the second upper light receiver can take place as long as the safety control device can detect from the time derivative of the sensor signal of the displacement measuring system or by means of a predefined time interval for the arrival of a switchover signal of a second switching device, which is assigned to the upper tool at a defined interval for the first switching device, that the low approach speed for the upper tool is maintained immediately before the arrival of the first engagement interval. In this case, the assumption is made that with the reduced, low approach speed (slow stroke) and in the remaining working gap between the upper tool and the workpiece placement surface, the user no longer runs the risk of intervening into the remaining working gap. Nevertheless, monitoring of the remaining working gap continues to be performed by the second lower light source and the assigned second lower light sensor, and this monitoring is deactivated by fading out of the sensor signal of the second lower light receiver only when the lower edge portion is positioned just before the reaching of the second engagement interval.

[0026] Additionally, the monitoring of the workpiece receiving space in the second operating mode is intended to include: This is especially true in the clamping cheeks of rotary bending machines or in upper tools formed as a prototype of the folding presses, which do not necessarily have to extend over the entire width of the respective bending machine and which therefore allow for lateral access into the workpiece receiving space, It also ensures protection against user intervention, which may take place by passing by the upper tool from the side, as may be the case in such circumstances.

[0027] Advantageously, the safety control device is configured for the selection of a third mode of operation, It is provided that in this third operating mode, an evaluation of the first said sensor signal and the second said sensor signal is provided. In this third operating mode, the handling space and the workpiece receiving space are simultaneously monitored, which makes it possible for the approach movement of the upper tool to the workpiece placement surface to take place entirely within the fast-forward stroke and without any need for switching to a slow-stroke. Furthermore, this makes it possible to monitor user interventions which may take place from the side, past the upper tool, into the workpiece receiving space.

[0028] For the third mode of operation, The safety protection control device includes: fade-out of the sensor signal of the second upper light receiver when a first safety clearance between the lower edge and the workpiece placement surface is exceeded; and A sensor signal of the second lower light source is faded out upon a second safety gap between the lower edge and the workpiece placement surface being violated. 1, since these sensor signals would otherwise be blocked by the upper tool during the closing movement of the upper tool.

[0029] In a further configuration of the invention it is provided that the first optical security device and the second optical security device are arranged in a fixed position on the machine bed. By way of example, it is contemplated that the first and second lower light sources and the first and second upper light sources are arranged at a first lateral edge portion of the workpiece placement surface extending transversely to the lower edge portion. It is further possible for the first and second lower light receiving portions and the first and second upper light receiving portions to be arranged at a second lateral edge portion of the workpiece placement surface extending transversely to the lower edge portion and, accordingly, to be arranged so as to be positioned exactly opposite the light source, respectively.

[0030] In yet another embodiment of the present invention, it is contemplated that the first optical security device and the second optical security device are linearly movably disposed on the machine bed. Advantageously, the first optical safety device and the second optical safety device are both arranged on a carrier which is mounted on the upper tool so as to be linearly movable, whereby it is provided that the carrier is configured for linear relative movement along a movement plane with respect to the upper tool. It is particularly advantageous that the carrier having a safety protection device accommodated therein is positioned first of all in a first functional position and, likewise, when the upper tool moves towards the workpiece placement surface, first of all does not perform any relative movement with respect to the upper tool, starting from the maximum distance of the upper tool from the workpiece placement surface. Only when the upper tool is brought close to the workpiece placement surface in such a way that the light rays emitted from the first and second lower light sources in the direction towards the first and second lower light receiving elements correspond to the second handling distance, is a relative movement between the carrier and the upper tool intended, and the carrier is accordingly moved from the first functional position to the second functional position. This relative movement ensures that, throughout the entire duration of the upper tool's approach movement, light beams emitted from the first and second lower light beam sources in the direction towards the first and second lower light beam receivers do not approach the workpiece placement surface closer than intended by the second handling distance. Advantageously, the carrier is preloaded by a spring in the first functional position relative to the upper tool, and when the upper tool moves towards the workpiece placement surface, it hits a stop assigned to the workpiece table, which results in an increase in spring stress and allows the desired relative movement between the upper tool and the carrier to take place, during which it is intended that the carrier is moved into the second functional position. During the subsequent movement of the upper tool away from the workpiece placement surface, the carrier is then lifted again from the stop and returns again to its first functional position.

[0031] Advantageously, it is provided that the safety control device is configured for controlling an adjustment device for positioning the first optical safety device and the second optical safety device between a first functional position and a second functional position. Thereby, an adaptation of the movement behavior between the carrier with the first and second optical safety devices accommodated in the carrier and the upper tool can be effected.

[0032] the upper tool is configured as a workpiece holder for fastening the workpiece on the workpiece table, and It is advantageous if the workpiece table is provided with bending cheeks extending along the front edge of the workpiece placement surface, the bending cheeks being pivotally mounted, In this case, the pivot axis of the bending cheek is aligned parallel to the lower edge and the front edge. In this embodiment of the upper tool, the deformation of the workpiece is carried out by a swivelling bending cheek, whereas the upper tool is responsible for pressing the workpiece onto the workpiece rest surface. Bending machines formed in this way are also called swivelling bending machines.

[0033] The object of the present invention is achieved according to a second inventive aspect by a method for the operation of a bending machine, the method comprising the following steps: a first operating mode for the workpiece with a lateral upturned fold behind the bending line and a second operating mode for the workpiece with a lateral upturned fold ahead of the bending line, Implementation of a selection method for the operation mode of the safety control device of the bending machine depending on the workpiece, - pushing the workpiece into the workpiece placement surface of the bending machine during a push-in movement in a push-in direction; the bending line of the workpiece is arranged in a movement plane, which is defined by a lower edge of an upper tool of the bending machine and a movement axis of the upper tool, which is supported so as to be linearly movable relative to the workpiece placement surface, activating a first optical security device by the security control device if the first mode of operation is selected; The first optical safety device is arranged in a handling space of the bending machine, which handling space extends from the upper tool in a direction opposite to the pushing-in direction in front of the plane of movement, or activating a second optical security device by the security control device if a second mode of operation is selected; In this case, the second optical safety device is arranged in a workpiece receiving space of the bending machine, which space extends from the upper tool in the push-in direction behind the movement plane. The steps are as follows.

[0034] The selection method can be implemented by manual user input at the bending machine or by evaluation of data sets in the machine control of the bending machine, for example provided by a higher-level control device. The aim of the selection method is that settings for the safety control device can be made taking into account the use or fade-out of the sensor signals of the first and second optical safety devices. The selection of the first operating mode is based on the fact that the workpiece has at least one lateral upturned fold, This raised fold portion induces, when the workpiece is positioned on the workpiece loading surface, an interruption of at least a second lower light beam by the raised fold portion during processing of the workpiece due to the arrangement of the bending line to be created in the workpiece in the movement plane of the lower edge portion. When the first operating mode is selected, no displacement-dependent fade-out of the sensor signal is necessary, so that the use of the displacement signal of the displacement measuring device can be omitted. Correspondingly, when the first operating mode is selected, a fade-out of the second optical security device is provided.

[0035] In the second operating mode, it is provided that the workpiece has at least one lateral upturned fold, This raised fold portion induces, when the workpiece is positioned on the workpiece loading surface, an interruption of the first lower light beam by the raised fold portion during processing of the workpiece due to the arrangement of the bending line to be created in the workpiece in the movement plane of the lower edge portion. Accordingly, upon selection of the second operating mode, a fade-out of the first optical security device is provided.

[0036] The workpiece is then preferably pushed onto the workpiece rest surface in a horizontally aligned pushing-in movement and is arranged relative to a movement plane defined by the lower edge of the upper tool and the movement axis for the upper tool in such a way that a bending line lies in said movement plane, which represents a line about which the unfolding of the partial region of the workpiece takes place in the course of the deformation method to be carried out by the bending machine.

[0037] Selection of the first operating mode is followed by activation of a first optical safety device, which protects a handling space starting from the upper tool and directed towards the user, In response to this, the second optical safety device is deactivated or faded out in order to avoid undesired interruptions of the processing step, which may occur in the event of blocking of the light beam of the second optical safety device, in particular the second lower light beam. In the first mode of operation, it is advantageously intended that no fading out or deactivation of the first optical security device takes place.

[0038] Subsequently, in the case of a bending machine configured as a pivoting bending machine, the upper tool approaches the workpiece in order to ensure the fixation of the workpiece on the workpiece table, and in the case of a bending machine configured as a folding press, directly to carry out the desired deformation process. For this purpose, a complete fade-out of the sensor signals of the first and second optical safety devices can be carried out.

[0039] If the first lower light beam or the first upper light beam of the first optical safety device is interrupted during the approach of the upper tool to the workpiece, This is detected by the safety control device using a sensor signal of the first lower light receiver or the first upper light receiver and triggers a shutdown of the drive for the upper tool.

[0040] Selection of the second operating mode is followed by activation of a second optical safety device, which protects the workpiece receiving space, which is directed towards the user from the upper tool, In response to this, the first optical safety device is deactivated or faded out in order to avoid undesired interruptions of the processing step, which may occur in the event of blocking of the light beam of the first optical safety device, in particular the first lower light beam.

[0041] Subsequently, in the case of a bending machine configured as a pivoting bending machine, an upper tool is brought into contact with the workpiece in order to ensure fixation of the workpiece on the workpiece table, and in the case of a bending machine configured as a folding press, directly in order to carry out the desired deformation process.

[0042] If the second lower light beam or the second upper light beam of the second optical safety device is interrupted during the approach of the upper tool to the workpiece, This is detected by the safety control device using a sensor signal of the second lower or second upper light receiver and triggers a shutdown of the drive for the upper tool.

[0043] When the first handling gap between the lower edge and the workpiece placement surface is exceeded, the sensor signal of the second upper light beam receiver is faded out.When the first handling gap between the lower edge and the workpiece placement surface is exceeded, the sensor signal of the second lower light beam receiver is faded out.

[0044] In some cases, in the event of a reliable interruption in the machining process for the workpiece, it is possible for the safety protection control device to induce a reverse movement for the upper tool in the first operating mode and / or in the second operating mode in order to quickly re-enlarge the working gap between the lower edge portion of the upper tool and the workpiece placement surface and thus further reduce potential dangers from the upper tool.

[0045] In a further configuration of the method, In the first mode of operation, during the approach of the upper tool to the workpiece placement surface, When a first safety clearance, also called the first handling clearance, between the lower edge of the upper tool and the workpiece surface is reached, there is no fade-out of the sensor signal of the first upper light receiver of the first optical safety device; and It is intended that when the second safety protection gap, also referred to as the second handling gap, between the lower edge portion of the upper tool and the workpiece placement surface is exceeded, there is no fade-out of the sensor signal of the first lower light receiving element of the first optical safety protection device. In this case, the first safety clearance (first handling clearance) and the second safety clearance (second handling clearance) are dimensioned, by way of example only, at distances of 12 mm and 6 mm from the workpiece placement surface.

[0046] In yet another embodiment of this method, In the second mode of operation, during the approach of the upper tool to the workpiece placement surface, a fade-out of the sensor signal of the second upper light receiver of the second optical safety device occurs when a first safety gap, also called a first engagement gap, between the lower edge of the upper tool and the workpiece surface is exceeded; and It is intended that when the second safety protection gap, also referred to as the second engagement gap, between the lower edge portion of the upper tool and the workpiece placement surface is exceeded, a fade-out of the sensor signal of the second lower light receiving element of the second optical safety protection device is performed. This fade-out avoids an undesired shutdown of the drive for the upper tool, A first safety clearance (first engagement clearance) and a second safety clearance (second engagement clearance) are provided from the workpiece placement surface, which clearances are, by way of example only, 12 mm and 6 mm, respectively. The dimensions are set so that at the time of fade-out of the respective sensor signal, the necessary reduction of potential dangers resulting from the approaching movement of the upper tool to the workpiece placement surface and to the workpiece placed on this workpiece placement surface is guaranteed.

[0047] In an advantageous further configuration of the method, During the implementation of the selection method for the workpiece-dependent operating mode of the safety control device of the bending machine, a third operating mode is provided for workpieces without side upturns; and When the third operating mode is selected, activation of the first optical security device and the second optical security device is performed by the security control device; and During the approach of the upper tool to the workpiece placement surface, A fade-out of a second sensor signal of a second upper light receiver of the second optical safety device occurs when a first safety clearance between the lower edge of the upper tool and the workpiece placement surface is exceeded; and It is intended that when the second safety clearance (6 mm) between the lower edge of the upper tool and the workpiece placement surface is exceeded, a fade-out of the sensor signal of the second lower light receiving element of the second optical safety protection device occurs.

[0048] The third operating mode is intended for the case where the workpiece does not have any contours protruding from its upper side, oriented parallel to the workpiece loading surface, which would induce undesired interruption of the light beams of the first and second optical safety protection devices. In this third operating mode, it is possible, in particular, for the approach of the upper tool to the workpiece surface to be carried out in the fast-forward stroke without switching to the slow-forward stroke, and it is advantageous if, for the complete approach of the upper tool to the workpiece surface in the fast-forward stroke, no fade-out of the first optical safety device takes place as a function of the displacement of the sensor signal.

[0049] Advantageous embodiments of the invention are illustrated in the drawings. [Brief description of the drawings]

[0050] [Figure 1] This is a front view of a bending machine, which is formed as a swivel bending machine, by way of example only, and which has a first optical safety protection device 51 and a second optical safety protection device 61 as well as an assigned safety protection control device 81. [Diagram 2] FIG. 2 is a schematic, partially sectioned, side view of the bending machine according to FIG. 1; [Diagram 3] FIG. 2 is a schematic, partially sectioned side view of a variant of the bending machine according to FIG. 1, in which the first optical safety device 51 and the second optical safety device 61 are arranged in a fixed position on the machine frame. [Figure 4] 1 is a schematic diagram of a workpiece having a raised fold behind a bending line; [Diagram 5] 1 is a schematic diagram of a workpiece having a raised fold before a bending line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] The bending machine 1 shown in Figures 1 and 2, which is formed, by way of example, as a swivel bending machine, has a machine bed 2, on which a workpiece table 3 is formed, which by way of example has a workpiece support surface 4 which is formed flat. 1 and 2, the rectangular workpiece placement surface 4 is horizontally oriented and extends from a front edge 32 visible in Fig. 1 to a rear edge 33 visible in Fig. 2. Furthermore, the workpiece placement surface 4 extends from a left lateral edge 34 to a right lateral edge 35.

[0052] Furthermore, a bending cheek 5 is arranged pivotably on the machine bed 2, which with its longest edge 31 runs along the front edge 32 of the workpiece placement surface 4. In their opposing end regions, the bending cheeks 5 are each attached to the bending machine 1 by means of a swivel link 6, 7. The swivel links 6, 7 have a common pivot axis 8 which is aligned parallel to the workpiece rest surface 4.

[0053] The working surface 10 of the bending cheek 5 can be pivoted by means of the pivoting drive 31 from the inoperative position shown in Figures 1 and 4, in which the working surface 10 is arranged parallel and flush with the workpiece-receiving surface 4, into the functional position shown in dashed lines in Figure 2, by a pivoting movement of the bending cheek 5. In this functional position, the working surface 10 occupies, by way of example, a right angle to the workpiece-receiving surface 4, other angular positions being possible as well. The introduction of the pivoting movement for the bending cheek 5 is carried out via a foot switch 9 which is connected to a machine control device 12 which is capable of open-loop or closed-loop control of the movement of the pivoting drive 31.

[0054] For the fastening of the workpieces 41 or 47 shown in Figures 4 and 5 on the workpiece table 3, a movable upper tool 21, also called clamping cheek, is provided which is mounted on the machine bed 2. The upper tool 21 is guided on both sides for linear movement in guide bars 15, 16 which are themselves fixed to the machine bed 2 by guide means not shown. The distance 22 between the lower edge 23 of the upper tool 21 and the workpiece table 3 can be adjusted by means of a spindle drive 17 , which comprises an electric motor 18 and a drive spindle 19 . 1 with a maximum distance 11 from the workpiece-receiving surface 4 and a second functional position, not shown, with a minimum distance 22 from the workpiece-receiving surface 4, can be carried out along a movement axis 24, which is drawn as a double-headed arrow, with a lower edge 23 of the upper tool 21 moving in a movement plane 25, which is shown in broken lines in FIGS. 1 and 2, during the movement of the upper tool 21 between the first and second functional positions, which movement plane 25 is oriented transversely to the workpiece-receiving surface 4 and includes the lower edge 23.

[0055] The upper tool 21 is assigned a first optical safety device 51 and a second optical safety device 61 .

[0056] The first optical security device 51 comprises a first lower light source 52, a first upper light source 53, a first lower light receiver 54, and a first upper light receiver 55. The second optical security device 61 comprises a second lower light source 62, a second upper light source 63, a second lower light receiver 64, and a second upper light receiver 65. Between the respective optical beam sources 52, 53 and 62, 63 and the assigned optical beam receivers 54, 55 and 64, 65, first lower and upper and second lower and upper laser beams 56, 57, 66, 67 extend, symbolically shown in the illustration drawn with various dashed lines. In order to be able to show all the laser beams 56, 57, 66, 67 in Fig. 1, they are shown at different distances relative to the workpiece placement surface 4. In practice, however, it is possible that the respective lower laser beams 56, 66 are arranged in a common horizontal plane and / or the respective upper laser beams 57, 67 are arranged in a common horizontal plane, as this can also be seen from Fig. 2.

[0057] The light sources 52, 53, 62, 63 can be formed, for example, as discrete laser diodes and are advantageously arranged such that the respective laser beams 56, 57, 66, 67 are emitted in the form of parallel beams having an approximately point-shaped cross section. By way of example, the light receivers 54, 55, 64, 65 are oriented such that the respective laser beams 56, 57, 66, 67 irradiate the respective light receivers 54, 55, 64, 65 in their respective areas, not shown, having maximum optical sensitivity.

[0058] Both optical safety devices 51, 61 are respectively mounted on holding devices 26 which are themselves arranged linearly displaceably on the upper tool 21 and allow a linear relative movement of the optical safety devices 51, 61 along the movement axis 24 relative to the upper tool 21. It is intended that the linear movement of the holding devices 26 relative to the upper tool 21 by the machine control device 12 is coordinated in such a way that the respective light source 52, 53, 62, 63 and the assigned light receiver 54, 55, 64, 65 are always located opposite each other.

[0059] The safety control device 81 is electrically connected via sensor lines (not shown) to the optical safety devices 51 and 61 and is designed for evaluating the sensor signals of the light receivers 54, 55, 64, 65 and for controlling the deactivation device 82. It is possible for the deactivation device 82 to be, for example, an electrical switch for the electric motor 18. In this way, it is possible for the safety control device 81 to cause a deactivation of the electric motor 18 by interruption of the energy supply, despite the provision of electrical energy to this electric motor 18 by the machine control device 12.

[0060] From the side view according to FIG. 2, only the light receiving elements 54, 55, 64, 65 are visible, whereas the respectively assigned light sources 52, 53, 62, 63 are not shown in FIG.

[0061] In FIG. 2, the plane of movement 25 is illustrated as a vertical plane and As well as a first functional position in which the lower edge portion 23 of the upper tool 21 has a maximum distance 22 to the workpiece placement surface 4, there is also a second functional position in which the upper tool 21 is only shown in dashed lines.

[0062] 2 it can further be seen that the first lower light receiver 54 and the first upper light receiver 55 are arranged adjacent to the movement plane 25 in the handling space 71. The handling space 71 extends from the movement plane 25 in the direction towards the front edge 32 of the workpiece placement surface 4 and furthermore extends accordingly along a push-in direction 91 which is used when inserting one of the workpieces 41 or 47 into the bending machine 1. This handling space represents a spatial area in which a user (not shown) handles the workpiece, from which, for example, the workpiece 41, 47 is inserted in a pushing direction 91 into the bending machine 1 or removed from the bending machine 1 along this pushing direction 91 after the deformation process has been carried out.

[0063] The second lower light receiving portion 64 and the second upper light receiving portion 65, on the other hand, are accommodated in a workpiece receiving space 72, which extends from the movement plane 25 in the direction towards the rear edge portion 33 of the workpiece placement surface 4 and, accordingly, in the pushing-in direction 91.

[0064] It is intended that, when moving the upper tool 21 with the optical safety protection devices 51, 61 accommodated therein from the first functional position according to FIG. 2 to the second functional position according to FIG. 2, at least no relative movement of the holding device 26 with respect to the upper tool 21 takes place. However, as soon as the lower laser beams 56, 66 approach a safety clearance (not shown), which may be, for example, 6 mm relative to the workpiece placement surface 4, a control of the drive (not shown) of the holding device 26 is carried out via the safety control device 81, so that the safety clearance of the lower laser beams 56, 66 remains constant despite further movements of the upper tool 21.

[0065] Depending on the selected operating mode for the bending machine 1, during this approach movement: Only the sensor signal of the first optical security device 51 (first operating mode) or Only the sensor signal of the second optical security device 61 (second operating mode) or The sensor signals of both optical safety devices 51, 61 (third operating mode) It is evaluated by the safety protection control device.

[0066] For example, if a workpiece 41, only diagrammatically shown in FIG. 4, is to be processed, which has a lateral upturned fold 42 which, for the intended bending process, needs to be arranged along a bending line 43 in the workpiece receiving space 72 of the bending machine 1, A first operating mode is selected for the bending machine 1, in which exclusively the sensor signal of the first optical safety device 51 is evaluated. Advantageously, in this first mode of operation, it is intended that there is no fade-out of the sensor signal of the first optical safety device 51 during the entire closing process for the upper tool.

[0067] For example, if a workpiece 47, only diagrammatically shown in FIG. 5, is to be processed, which has a lateral upturned fold 48, which for the intended bending process has to be arranged along a bending line 49 in the handling space 71 of the bending machine 1, A second operating mode is selected for the bending machine 1, in which exclusively the sensor signal of the second optical safety device 61 is evaluated. Advantageously, in this second operating mode, a displacement-dependent fade-out of the sensor signal of the second optical safety device 61 is performed during the closing process for the upper tool. That is what is intended.

[0068] The variant of the bending machine 99 shown in FIG. 3 differs from the variant of the bending machine 1 according to FIGS. 1 and 2 only by the arrangement of both optical safety protection devices 51 and 61, which in this variant are arranged in a fixed position on the machine bed 2. Otherwise, the components of the bending machine 99 are formed in the same way as the bending machine 1, therefore the same reference numbers are used for these components and a further description of these components and their functions is omitted.

Claims

1. A bending machine (1;99), The bending machine has a machine bed (2), A workpiece table (3) is formed on the machine bed, which has a workpiece placement surface (4) designed for placement of the workpiece (41; 47), and The bending machine has an upper tool (21) supported on the machine bed (2) so as to be linearly movable along a movement axis (24), The upper tool has a lower edge (23) arranged adjacent to the workpiece placement surface (4), said lower edge portion (23) together with said axis of movement (24) defines a plane of movement (25); In this plane of movement (25), the lower edge portion (23) is movable between an open position for the upper tool (21) and a closed position for the upper tool (21), the transfer plane (25) separates a handling space (71) extending from the upper tool (21) in the direction of the front edge (32) of the workpiece placement surface (4) from a workpiece receiving space (72); This workpiece receiving space extends from the upper tool (21) to the rear edge (33) of the workpiece placement surface (4), and A first optical security device (51) is arranged in the handling space (71) and a second optical security device (61) is arranged in the processing material receiving space (72), and The bending machine has a safety protection control device (81), the safety control device is configured for evaluating a first sensor signal of the first optical safety device (51) and a second sensor signal of the second optical safety device (61) and for deactivating a spindle drive (17) assigned to the upper tool (21) as a function of the first and / or second sensor signals, the safety control device (81) is designed for switching between a first operating mode, in which exclusively the first sensor signal is evaluated, and a second operating mode, in which exclusively the second sensor signal is evaluated. A bending machine (1;99) characterized in that

2. The first optical security device (51) comprises: a first lower light source (52) configured to provide a first lower light beam (56) that is parallel to said lower edge (23); and a first lower light receiving portion (54) configured for receiving said first lower light beam (56); and The first optical security device (51) comprises: a first upper light source (53) configured to provide a first upper light beam (57) parallel to said lower edge (23); and a first upper light receiving portion (55) which is formed for receiving said first upper light beam (57), the first lower light source (52) is spaced closer to the workpiece placement surface (4) than the first upper light source (53); 2. The bending machine (1; 99) according to claim 1, characterized in that

3. The second optical security device (61) comprises: a second lower light source (62) configured to provide a second lower light beam (66) that is parallel to the lower edge (23); and a second lower light receiving portion (64) which is formed for receiving said second lower light beam (66); and The second optical security device (61) comprises: a second upper light source (63) configured to provide a second upper light beam (67) parallel to said lower edge (23); and a second upper light receiving portion (65) which is formed for receiving the second upper light beam (67), the second lower light source (62) is spaced closer to the workpiece placement surface (4) than the second upper light source (63); 3. A bending machine (1; 99) according to claim 1 or 2, characterized in that

4. The safety protection control device (81) in the first operating mode: During the closing movement of the upper tool (21), 4. The bending machine (1; 99) according to claim 1, characterized in that it is formed for evaluating the sensor signal of the first upper light receiving portion (55) and for evaluating the sensor signal of the first lower light receiving portion (54).

5. In the second operating mode, the safety protection control device (81) - fading out the sensor signal of the second upper light receiving element (65) when the first engagement interval between the lower edge (23) and the workpiece placement surface (4) is exceeded; and 5. The bending machine (1; 99) according to claim 1, characterized in that the second lower light receiving portion (64) is designed to fade out the sensor signal when the second engagement distance between the lower edge portion (23) and the workpiece placement surface (4) decreases.

6. the safety control device (81) being configured for selection of a third mode of operation, 6. The bending machine (1; 99) according to claim 1, characterized in that in this third operating mode, an evaluation of the first sensor signal and of the second sensor signal is provided.

7. In a third operating mode, the safety protection control device (81) - fading out the sensor signal of the second upper light receiver (65) when a first safety clearance between the lower edge (23) and the workpiece placement surface (4) is exceeded; and fade-out of the sensor signal of the second lower light source (62) when a second safety clearance between the lower edge (23) and the workpiece placement surface (4) is exceeded; 7. The bending machine (1; 99) according to claim 6, characterized in that it is formed for

8. 8. The bending machine (1; 99) according to claim 1, characterized in that the first optical security device (51) and the second optical security device (61) are arranged on the machine bed (2) in a fixed position.

9. 9. The bending machine (1; 99) according to claim 1, characterized in that the first optical safety device (51) and the second optical safety device (61) are arranged on the machine bed (2) so as to be linearly movable.

10. the upper tool (21) is configured as a workpiece holder for fastening the workpiece (41; 47) on the workpiece table (3), and A bending cheek (5) is mounted on the workpiece table (3) so as to be pivotable along the front edge (32) of the workpiece placement surface (4), the pivot axis (8) of the bending cheek (5) is aligned parallel to the lower edge (23) and the front edge (32); 10. A bending machine (1; 99) according to any one of claims 1 to 9, characterized in that

11. A method for the operation of a bending machine (1;99), said method comprising the following steps: a first operating mode for the workpiece (41) with a lateral upturned fold (42) behind the bending line (43) and a second operating mode for the workpiece (47) with a lateral upturned fold (48) ahead of the bending line (49), Implementation of a selection method for the operating mode, depending on the workpiece, for a safety control device (81) of a bending machine (1;99), - pushing the workpiece (41; 47) into the workpiece placement surface (4) of the bending machine (1; 99) during a pushing movement in a pushing direction (91), In this case, the bending line (43; 49) of the workpiece (41; 47) is arranged in a movement plane (25), which is defined by a lower edge (23) of an upper tool (21) of the bending machine (1; 99) and a movement axis (24) of the upper tool (21) which is supported so as to be linearly movable relative to the workpiece placement surface (4), activating a first optical security device (51) by a security control device (81) if a first mode of operation is selected; In this case, the first optical safety device (51) is arranged in a handling space (71) of the bending machine (1; 99), which handling space extends from the upper tool (21) in front of the movement plane (25) in opposition to the pushing-in direction (91), or activating a second optical security device (61) by the security control device (81) if a second mode of operation is selected; In this case, the second optical safety device (61) is arranged in a workpiece receiving space (72) of the bending machine (1; 99), which runs from the upper tool (21) in the pushing-in direction (91) behind the movement plane (25). A method comprising the steps of:

12. In the first mode of operation, during the approach of the upper tool (21) to the workpiece placement surface (4), - when a first safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 12 mm and 15 mm, is exceeded, there is no fade-out of the sensor signal of the first upper light receiver (55) of the first optical safety device (51); and that when a second safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 6 and 8 mm, is violated, there is no fade-out of the sensor signal of the first lower light receiver (54) of the first optical safety device (51); The method according to claim 11, characterized in that

13. In the second mode of operation, during the approach of the upper tool (21) to the workpiece placement surface (4), - when a first safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 12 mm and 15 mm, is exceeded, a fade-out of the sensor signal of the second upper light receiver (65) of the second optical safety device (61) is performed; and a fade-out of the sensor signal of the second lower light receiver (64) of the second optical safety device (61) occurs when a second safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 6 mm and 8 mm, is exceeded; The method according to claim 11, characterized in that

14. - during the implementation of the selection method for the workpiece-dependent operating mode of the safety control device (81) of the bending machine (1), a third operating mode is provided for workpieces without lateral upturned folds; and When the third operating mode is selected, activation of the first optical security device (51) and the second optical security device (61) is performed by the security control device (81); and During the approach of the upper tool (21) to the workpiece placement surface (4), - a fade-out of a second sensor signal of a second upper light receiver (65) of the second optical safety device (61) occurs when a first safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 12 mm and 15 mm, is exceeded; and a fade-out of the sensor signal of the second lower light receiver (64) of the second optical safety device (61) occurs when a second safety clearance between the lower edge (23) of the upper tool (21) and the workpiece placement surface (4), in particular between 6 mm and 8 mm, is exceeded; The method according to claim 11, characterized in that

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